RARE DISEASE
Cryptococcosis
Cryptococcosis
Cryptococcosis
Drug discovery
7
drugs
With orphan designations
Overview
Cryptococcosis is a systemic fungal infection caused by Cryptococcus neoformans or C. gattii, primarily acquired via inhalation of environmental spores. It manifests as pulmonary disease or disseminated infection, notably cryptococcal meningitis, particularly in immunocompromised individuals. Diagnosis relies on antigen testing (serum/CSF), culture, or histopathology. Treatment varies by severity: localized pulmonary cases may resolve without intervention, while CNS involvement requires induction with amphotericin B-based regimens and flucytosine, followed by fluconazole maintenance [1][4][8].
Population
Primarily affects immunocompromised individuals (HIV/AIDS with CD4 <100 cells/μL, solid organ transplant recipients, long-term corticosteroid users) [1][6][9].
C. gattii infections increasingly reported in immunocompetent hosts, particularly in regions like the Pacific Northwest and Australia [1][6][13].
Burden
Global: Accounts for 19% of AIDS-related deaths, with ~152,000 annual meningitis cases and 112,000 deaths, predominantly in sub-Saharan Africa [3][7][11][15].
Mortality: Up to 70% in low-resource settings; 10–15% in high-income regions with optimal care [2][11][12].
U.S. incidence: 0.4–1.3 cases/100,000 population, rising in non-HIV populations (e.g., organ transplant recipients) [6][18].
Prompt diagnosis, targeted antifungal therapy, and immune reconstitution (e.g., antiretroviral therapy in HIV) are critical to reducing mortality [8][17].
Therapies
Induction: Liposomal amphotericin B (3–4 mg/kg/day) + flucytosine (100 mg/kg/day) for 7–14 days [4][8][17].
Consolidation/Maintenance: Fluconazole (800–1200 mg/day) for 8 weeks, then 200 mg/day until immune recovery [5][10].
Screening: Cryptococcal antigen (CrAg) testing in HIV patients with CD4 <200 cells/μL to preempt disseminated disease [4][17].
Categories: rare infectious diseases
Research Papers
2,680 drug discovery papers about Cryptococcosis, with 14 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2,680 drug discovery papers about Cryptococcosis, with 14 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
small molecules
2026-09-30 | Molecular types, clinical profile, and exploratory virulence-associated phenotypes of clinical Cryptococcus isolates from Amazonas, Brazil.
Cryptococcosis remains a severe systemic mycosis, especially among people living with HIV/AIDS, and culture-based molecular data from Amazonas remain limited. The aim was to identify which Cryptococcus molecular types circulated among clinical isolates from Amazonas between 2020 and 2024; what were the main clinical characteristics and outcomes of patients infected with Cryptococcus neoformans molecular type VNI and Cryptococcus gattii molecular type VGII; and whether these molecular types differed in selected susceptibility-related and virulence-associated phenotypes. We analyzed 70 culture-confirmed clinical isolates from patients treated at the Dr. Heitor Vieira Dourado Tropical Medicine Foundation, Manaus, Brazil. Molecular types were assigned by URA5 PCR-RFLP using reference strains. Demographic and clinical variables were retrieved from medical records. A stratified 30-isolate subset comprising 24 VNI and 6 VGII isolates was evaluated for phospholipase activity and melanization. Fluconazole MICs were analyzed for the complete 70-isolate dataset and were determined by broth microdilution according to CLSI M27-A4. VNI predominated (64/70; 91.4%), whereas VGII accounted for 6/70 isolates (8.6%). The series was predominantly composed of men, young adults, and HIV-positive patients. HIV infection was more frequent among VNI cases, whereas VGII included proportionally more HIV-negative patients. In-hospital death occurred in 17/70 patients (24.3%). Fluconazole MICs, phospholipase activity, and melanization were broadly comparable between VNI and VGII, although the small VGII subgroup precluded robust genotype-associated inference. VNI was the dominant molecular type in this severe reference-center cryptococcosis series from Amazonas. Phenotypic findings should be interpreted as exploratory and hypothesis-generating.
2026-09-03 | Discovery of Novel Ligands for the Treatment of Cryptococcus neoformans Infection.
Fungal pathogens are an escalating global public health concern, particularly in the context of invasive and opportunistic infections. Cryptococcosis, primarily caused by Cryptococcus neoformans var. grubii, can affect multiple organs and often leads to life-threatening meningitis in immunocompromised individuals. Given limited antifungal therapies and emergence of resistance and toxicity-related constraints, the development of novel anti-cryptococcal agents remains an urgent priority. A library of innovative 3-hydroxypyridin-4(1H)-one-based hybrids (5a-f) was synthesized and evaluated for antimicrobial activity against clinically relevant Gram-positive and Gram-negative bacteria, as well as fungal species Candida albicans and C. neoformans var. grubbi. Safety was assessed through cytotoxicity studies in HEK293 and HepG2 cells and hemolytic evaluation, while iron-chelating capacity and lipophilicity were also investigated. All compounds formed stable iron(III) complexes and displayed no significant toxicity up to 25 μM. Series 1 compounds (5a-c) were less lipophilic than Series 2 (5d-f), mainly due to regioisomeric position of hydroxyl group on 2-methyl-4-pyridone scaffold, whereas fluorination increased lipophilicity in both series. Notably, compounds 5c-f emerged as potent, selective, and nontoxic antifungal agents against C. neoformans var. grubii (MIC < 16 µg/mL; CC50 > 32 µg/mL; HC10 > 32 µg/mL), highlighting the potential of 3-hydroxypyridin-4(1H)-one-based hybrids as a promising approach for cryptococcal meningitis therapy.
2026-09-01 | Pulmonary Cryptococcosis in an Immunocompetent Young Adult Male : A Case Report
Cryptococcosis mainly affects immunocompromised hosts but can also occur in immunocompetent individuals, often presenting with non-specific pulmonary radiological lesions and asymptomatic clinical course, which frequently causes misdiagnosis and delayed treatment. Diagnostic challenges arise when central nervous system (CNS) involvement is suspected despite negative initial cerebrospinal fluid (CSF) microscopy findings. We present a 24-year-old previously healthy immunocompetent male with incidental left lung infection detected on chest CT, who remained completely asymptomatic. Empirical oral antibiotic treatment resulted in only minimal improvement of lung lesions. Laboratory tests showed positive serum cryptococcal polysaccharide antigen. Bronchoalveolar lavage mNGS detected Pneumocystis jirovecii and Klebsiella aerogenes, with elevated BAL galactomannan level. Lumbar puncture revealed elevated CSF protein, neutrophil-predominant pleocytosis and weakly positive Pandy’s test, while India ink staining and culture were negative for cryptococci. The patient had normal CD4 count, confirming intact immune function. Induction therapy with liposomal amphotericin B plus flucytosine was initiated for presumed cryptococcal meningoencephalitis. Transient liver enzyme elevation and hypokalemia occurred during treatment, which were effectively corrected by symptomatic management, and the patient was discharged in stable condition. This case indicates that positive serum cryptococcal antigen in patients with pulmonary nodules requires mandatory CNS evaluation even without typical meningeal symptoms. Negative CSF India ink cannot exclude cryptococcal meningitis. Incidental detection of Pneumocystis jirovecii by mNGS in immunocompetent individuals raises concerns about colonization or subclinical infection. Clinicians should interpret mNGS results cautiously and determine the true pathogen based on comprehensive clinical information. Pulmonary cryptococcosis should be considered for persistent unexplained pulmonary lesions regardless of immune status; early serological screening, routine lumbar puncture to rule out occult CNS dissemination, and timely standardized antifungal therapy are essential to improve diagnostic accuracy and clinical prognosis.
2026-08-27 | Synergic Effect of Fluconazole and Quinoline Derivatives Combination Against Cryptococcus spp., Mechanisms of Action and Toxicity.
Cryptococcosis is a severe fungal infection affecting immunocompromised individuals, with treatment limited to FLZ, AMB, and FC. This study investigated the antifungal potential of fluconazole (FLZ)-, amphotericin B (AMB)-, 8-hydroxyquinoline (8HQ)-, and clioquinol (CQ)-based combinations against Cryptococcus neoformans and C. gattii. Drug interactions were assessed by checkerboard assay, followed by time-kill curves, irritability, toxicity, and virulence factors inhibition tests. The FLZ + AMB combination showed weak synergism, whereas FLZ combined with CQ or 8HQ exhibited strong synergistic effects (p < 0.001) at low concentrations (0.125-0.25 µg/mL), up to three times greater than those of FLZ + AMB. This effect persisted across other strains, including less FLZ-susceptible isolates. Moreover, FLZ + CQ inhibited melanin production in both species without causing significant irritability or toxicity in the tested models. These results indicate that combining drugs with distinct mechanisms of action can enhance antifungal efficacy while potentially reducing treatment doses. The FLZ + CQ/8HQ combinations represent promising candidates for future in vivo models for therapeutic evaluation.
2026-08-17 | Investigating the therapeutic potential of the antibacterial drug nitroxoline in combating cryptococcal infection.
Cryptococcosis is a major health threat among immunocompromised individuals, resulting in life-threatening consequences secondary to brain invasion. The limited treatment options and the increased incidence of treatment failure and relapses urge the need for more effective therapies. In this study, we investigated the therapeutic potential of nitroxoline (NTX) in treating cryptococcal infection. NTX exhibited potent fungicidal activity against Cryptococcus neoformans/gattii clinical isolates, with an MIC90 of 1 µg/mL. In addition, NTX substantially inhibits the main virulence traits of cryptococcal cells, including the polysaccharide capsule, melanin production, and the urease enzyme, which are crucial for the infection progression. In exploring the potential mechanism of action, our results revealed the relationship between the metal-chelating properties of the NTX scaffold and its antifungal activity. Interfering metal chelation, either through structural modification or exogenous supplementation with varied divalent cations, significantly reduced the antifungal and anti-virulence activities of NTX. Given its potential therapeutic role, we evaluated the interaction between NTX and the clinically used antifungals amphotericin B, flucytosine and fluconazole. Additionally, we investigated the tendency of cryptococcal cells to develop resistance following repeated exposure to NTX, as well as its efficacy in the Caenorhabditis elegans nematode model of cryptococcal infection. Notably, cryptococcal cells exhibited consistent susceptibility to NTX upon repeated exposure to a subinhibitory concentration. In the C. elegans model, NTX significantly reduced the fungal burden of the infected worms, achieving a 2-log10 reduction, and consistently enhanced their survival compared to untreated group. These findings highlight the potential role of the NTX scaffold in combating cryptococcal infection that warrants further investigation.
vaccines
2026-09-24 | A protective hybrid protein vaccine informed by mapping major histocompatibility class II epitopes in Cryptococcus neoformans chitin deacetylases that stimulate CD4 + T cell responses.
Infections due to Cryptococcus species are estimated to cause over 100,000 deaths a year. No cryptococcal vaccines are approved for human use. We have shown that vaccine formulations consisting of C. neoformans chitin deacetylase (Cda)2 and Cda1 adjuvanted with Cationic Adjuvant Formulation 01 (CAF01) protect mice against experimental cryptococcosis by a mechanism dependent upon CD4 + T cells. Here, using overlapping peptide libraries, we mapped epitopes in Cda2 and Cda1 that stimulated interferon-gamma (IFNγ) release from splenocytes of C57BL/6 and DR4 mice immunized with these proteins. DR4 mice lack mouse major histocompatibility class II (MHC-II) proteins and express chimeric MHC-II proteins with the specificity of the human HLA-DR allele, HLA-DRB1*04:01. Experimental results were then compared with MHC-II binding predictions using the Immune Epitope Database (IEDB) NetMHCIIpan 4.1 BA MHC-II epitope prediction tool. Unique epitopes in Cda2 and Cda1 were discovered for each mouse strain, some of which were not predicted to bind well to MHC-II. CD4 + T cells were responsible for cytokine release as IFNγ production was lost if CD4 + T cells were depleted from the splenocyte population. Finally, we tested a hybrid recombinant protein that consisted of portions of Cda2 and Cda1 containing the MHC-II/CD4 + T cell epitopes which induce CD4 + T cells in DR4 mice. When administered as a CAF01-adjuvanted vaccine, the hybrid protein protected DR4 mice from an otherwise lethal C. neoformans pulmonary challenge. These results provide a proof of principle regarding the utility of MHC-II/CD4 + T cell epitope mapping in cryptococcal vaccine development. The development of vaccines to prevent cryptococcosis, a fungal disease which causes over 100,000 deaths annually, is a public health priority. We have demonstrated that adjuvanted vaccines containing two Cryptococcus neoformans protein antigens, chitin deacetylase (Cda)2 and Cda1, protect mice against experimental cryptococcosis by a mechanism dependent upon CD4 + T cells. In this study, we determined which 15 amino acid peptides of Cda2 and Cda1 stimulate CD4 + T cells in C57BL/6 and DR4 mice; the latter mouse strain has human major histocompatibility class II (MHCII) specificity. We then synthesized a small hybrid protein containing those portions of Cda2 and Cda1 that strongly stimulated CD4 + T cell responses in DR4 mice. As an adjuvanted vaccine, the hybrid Cda2/1 protein protected DR4 mice from a C. neoformans pulmonary challenge. Thus, CD4 + T cell/MHCII epitope mapping experimentally validated the design of a protective multi-epitope protein for use in cryptococcal vaccines.
2026-06-17 | Systematic infectome-phenome profiling reveals cryptococcal infection-associated proteins driving immune system remodeling and immunization potential.
Invasive fungal infections are an escalating global health challenge driven by host immune status and antifungal resistance. Here, we present an integrated infectome-phenome platform that combines high-resolution proteomics with systematic phenotypic profiling to map host-pathogen interactions in Cryptococcus neoformans. This approach captures coordinated host immune suppression alongside complementary fungal virulence programs and enables the prioritization of infection-associated proteins. Phenome fingerprinting of targeted mutants resolves functional relevance and therapeutic potential, supported by in vitro assays and a murine model of cryptococcosis. We identify a conserved, previously uncharacterized protein, CipC, that alters extracellular vesicle composition and enhances antigenicity. Immunization with CipC-derived vesicles elicits a robust and diversified host immune response, highlighting a role for fungal vesicles in immune priming. Together, this work establishes a scalable framework to define functional drivers of fungal infection and accelerate discovery of therapeutic and immunological targets across pathogenic fungi.
2026-06-01 | Acetylation and accessibility of Cryptococcus neoformans cell wall chitosans influence the strength of host immune responses.
The fungal pathogen Cryptococcus neoformans causes fatal cryptococcal meningitis, a significant global health risk. Unlike most fungi, C. neoformans expresses chitin deacetylases that convert its cell wall chitin into chitosan, helping to evade chitin-triggered host immunity. However, it is unclear how the properties and accessibility of these chitosans vary between strains and growth conditions, and how they influence the host immune response. To show how chitin deacetylase activity and growth conditions shape the properties of cell wall chitosans, we present the first comprehensive analysis of the chitosan content, fraction of acetylation (FA), enzymatic degradation products by host chitinases, and accessibility in various Cryptococcus strains, including chitin deacetylase mutants, cultivated under different conditions. Certain chitin deacetylase knockouts, as well as challenging growth conditions, lead to higher FAs and enhanced exposure, associated with stronger host immune responses. The response to cryptococcal chitin/chitosan ranges from low (resulting in cryptococcosis) to adequate (providing effective host defense) and excessive (leading to hyper-inflammation). Correlation between the strength of the immune response and the abundance of chitin-binding proteins was used to rapidly screen a multitude of strains and growth conditions for their immunogenic potential. Our approach provides insight into Cryptococcus-related disease caused by insufficient and excessive immune responses, and may accelerate the development of effective cell-based vaccines.
2026-03-10 | mGem: Progress on the development of conjugate vaccines for Cryptococcus neoformans infections.
Cryptococcus neoformans is an important fungal pathogen that causes cryptococcosis, a life-threatening disease predominantly affecting immunocompromised individuals. Current estimates suggest that cryptococcosis is responsible for over 150,000 deaths annually, highlighting the need for the development of effective preventive measures. Early research utilizing polysaccharide filtrates (CneF) laid the groundwork for polysaccharide-containing vaccines, demonstrating partial protection in murine infection models. Further vaccine constructs made with purified extracellular polysaccharides (EPS) conjugated to protein carriers elicited strong antibody responses and enhanced survival. Recently, more attention was given to the purified capsule components glucuronoxylomannan (GXM) and glucuronoxylomannogalactan (GXMGal), with studies indicating that GXM conjugates can elicit protective effects. The development of semisynthetic polysaccharide-based vaccines offers a new approach to addressing lot-to-lot variability, enhancing consistency. In conclusion, strategies that advance from early crude formulations to more sophisticated conjugate and synthetic vaccines hold great promise for developing an effective vaccine to prevent and treat cryptococcal diseases.
2025-12-24 | Vaccine-Mediated Protection of Mice Against African and Asian Clinical Strains of Cryptococcus neoformans.
Infections with strains of the Cryptococcus neoformans species complex are responsible for over 100,000 deaths per year, predominantly due to meningitis in immunocompromised individuals. Despite much research, there are no licensed fungal vaccines available. Most experimental cryptococcal vaccine formulations have been tested in preclinical models using laboratory strains of C. neoformans, particularly H99 and KN99. However, to be effective, vaccines need to protect against the wide variety of cryptococcal isolates found worldwide, particularly in regions that have the highest burden of infections. Therefore, we explored vaccine-mediated protection of BALB/c mice against experimental cryptococcosis due to six C. neoformans strains originally isolated from patients with cryptococcal meningitis in Vietnam, Uganda, and Botswana. Two vaccines were tested: a live-attenuated C. neoformans vaccine lacking three chitin deacetylase genes, and a quadrivalent subunit protein vaccine adjuvanted with Cationic Adjuvant Formulation 01. When compared to unvaccinated mice, both vaccines provided significant protection against all six clinical strains. However, the degree of protection varied as a function of vaccine formulation and clinical strain. Lung leukocytes from vaccinated and infected mice had significantly increased antigen-stimulated interferon-gamma production compared with infected but unvaccinated mice. Thus, although the degree of protection varied, two cryptococcal vaccines significantly protected mice against experimental infection with cryptococcal strains representative of regions of the world that account for the majority of cryptococcal meningitis cases found globally. These data provide preclinical support for trialing vaccines in persons at high risk for developing cryptococcosis.
proteins
2026-09-11 | New approaches for cryptococcosis treatment and prevention-a systematic review.
Cryptococcosis remains a life-threatening fungal infection with high mortality despite current antifungal therapy. The toxicity, limited accessibility, poor tissue penetration, and increasing resistance associated with conventional antifungals highlight the need for innovative preventive and therapeutic strategies. This systematic review summarises recent advances in cryptococcosis management and identifies priorities for future research and clinical translation. PubMed, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov were systematically searched for studies published between January 2005 and December 2025. Data on study characteristics, therapeutic strategies, mechanisms, and outcomes were extracted. Because of substantial heterogeneity among clinical and preclinical studies, quantitative synthesis and certainty-of-evidence assessment were not performed. Eighty-six studies were included. Promising advances were identified in vaccines, immunotherapy, nanotechnology-based drug delivery, novel antifungal agents, drug repurposing, and non-pharmacological interventions. Vaccine candidates induced protective immunity in animal models but remain preclinical. Adjunctive interferon-γ is the only immunotherapy supported by clinical evidence, whereas programmed cell death protein 1 (PD-1) blockade, chimeric antigen receptor T-cell (CART) therapy, most of monoclonal antibodies, and other immunomodulators remain under preclinical investigation. MAT2203 demonstrated non-inferior efficacy with improved safety compared with intravenous amphotericin B. Several novel antifungal agents have entered clinical development, whereas repurposed drugs have shown limited clinical benefit. Most non-pharmacological approaches also remain experimental. Emerging strategies are reshaping cryptococcosis management beyond conventional antifungal therapy. Although most remain at the preclinical or early clinical stage, advances in host-directed immunotherapy, nanomedicine, and novel antifungal development provide promising opportunities to improve treatment efficacy, safety, and accessibility. Well-designed clinical studies are needed to facilitate clinical translation.
2026-08-17 | Temporal shifts in adaptive immunity drive HIV-associated cryptococcal IRIS: mechanisms, models, and therapeutic opportunities.
Cryptococcal meningoencephalitis (CME) remains a leading cause of AIDS-related mortality, and up to one-quarter of persons living with HIV who survive CME develop cryptococcal immune reconstitution inflammatory syndrome (CME-IRIS) after antiretroviral therapy (ART) initiation. CME-IRIS arises when recovering immunity encounters a high residual fungal antigen burden, yet the temporal adaptive immune dynamics that distinguish protective reconstitution from damaging neuroinflammation are not fully defined. This review synthesizes clinical and experimental data to propose a temporal framework centered on CD4+ T cell polarization, regulatory failure, memory T cell quality, and T-B cell coordination. Before ART, many patients exhibit a Th2-skewed, low-inflammatory state with impaired Th1 responses, reduced antifungal IgM production, and deficient Tfh-B cell coordination, collectively favoring persistent Cryptococcus neoformans antigen burden. With ART, IL-7-driven T cell recovery, Th17/Treg imbalance, Th1/Th17-biased memory responses, and chemokine-guided trafficking of CXCR3+CCR5+ effector cells into the central nervous system can convert this antigen-rich milieu into fulminant neuroinflammation. We further discuss emerging mouse models that recapitulate unmasking CME-IRIS, the contrasting immune profile of Cryptococcus gattii-associated IRIS as a comparative model, and developing therapeutic strategies that include targeted immunomodulators, cell-based therapies, and vaccines. Finally, we highlight future directions - particularly single-cell and spatial transcriptomic profiling of blood and CSF - to resolve which adaptive immune populations drive neuroinflammation and to validate predictive biomarkers for CME-IRIS. A temporally informed view of adaptive immunity in CME-IRIS may refine ART timing, guide risk stratification, and identify new adjunctive interventions for cryptococcosis and related IRIS syndromes.
2026-07-14 | Sphingomyelin synthase 2 regulates host protection conferred by the administration of Cryptococcus neoformans Δsgl1 strain.
Sphingolipids are fundamental components of the plasma membrane that regulate immune receptor organization and host responses to infection. Here, we identify sphingomyelin synthase 2 (SMS2) as a critical mediator of antifungal host defense against Cryptococcus neoformans. SMS2 deficiency reduces sphingomyelin and increases ceramide levels, altering membrane lipid composition and impairing receptor localization. This is associated with decreased plasma membrane toll-like receptor 2, attenuated signaling, and reduced IL-17A and IFNγ production by γδ T cells. Macrophages lacking SMS2 exhibit impaired phagocytosis, resulting in inefficient clearance of the attenuated C. neoformans Δsgl1 strain. Consequently, SMS2-deficient mice fail to develop effective vaccine-induced protection and show increased susceptibility to secondary infection with WT C. neoformans. Mechanistically, bSMase-driven alterations in SM/ceramide balance are associated with disruption of membrane organization and reduced toll-like receptor 2 and cholera toxin B staining, suggesting that SMS2-dependent sphingomyelin regulation represents a key mechanism linking membrane lipid composition to innate immune signaling, phagocytosis, and antifungal host defense against C. neoformans.
2026-01-16 | Conjugation of a Cryptococcus neoformans-derived metalloprotease to antifungal-loaded PLGA nanoparticles treats neural cryptococcosis in an in vitro model.
Overcoming the blood-brain barrier to deliver therapeutics is a major hurdle in treating diseases of the central nervous system. We engineered 4-arm carboxyl terminated poly(D,L-lactide-co-glycolide) nanoparticles with the fungal metalloprotease Mpr1, an enzyme utilized by the neurotropic pathogen Cryptococcus neoformans (Cn) to cross the blood-brain barrier. Nanoparticles were prepared using a modified single emulsion solvent evaporation technique, and characterized in terms of shape, size, zeta potential, encapsulation efficiency, and toxicity to brain microvascular endothelial cells. Mpr1-functionalized nanoparticles had increased penetration over non-functionalized nanoparticles in an in vitro model of the blood-brain barrier. When encapsulating amphotericin B, a potent antifungal drug, Mpr1-functionalized nanoparticles reduced fungal burden in an in vitro model of neural cryptococcosis. Loaded nanoparticles also had an 8-fold lower minimum inhibitory concentration against Cn and Candida albicans (Ca) compared to unencapsulated amphotericin B. Results indicate that Mpr1-coating of polymeric nanoparticles is a promising strategy to enhance drug delivery to the brain.
2025-09-10 | Acute Toxicity and Genotoxicity of cMoL, a Lectin From Moringa oleifera Seeds With Antifungal Activity Against Cryptococcus Strains.
Coagulant Moringa oleifera lectin (cMoL) is one of the compounds involved in the application of M. oleifera seeds for traditional water treatment methods. The present study highlights the new biotechnological potential of cMoL lectin as an antifungal agent against Cryptococcus neoformans B3501 and H99 and Cryptococcus gattii R265 strains. Acute toxicity and genotoxicity were assessed to provide information on security utilization. The antifungal activity was evaluated using the broth microdilution test, flow cytometry, antibiofilm activity, and synergistic effects with fluconazole. Acute toxicity was determined by administering a single dose of cMoL (200 mg/kg) to female Swiss albino mice and examining the following parameters: water and feed consumption, weight variation, blood hematological and biochemical parameters, serum cytokine levels, and histopathological analyses. Genotoxicity was assessed using comet assay and micronucleus test. cMoL inhibited the growth of all tested isolates, with a minimal inhibitory concentration of 7.5 μg/mL. Flow cytometry data showed that cMoL (7.5 μg/mL) significantly decreased cell viability by promoting necrosis. cMoL was not found to be an antibiofilm agent against Cryptococcus species; however, it acted synergistically with fluconazole against C. neoformans H99. cMoL (200 mg/kg) did not cause animal death or toxicity. No hematological, biochemical, histopathological, or genotoxic effects were observed. These results encourage the exploration of cMoL as a natural and safe antifungal agent against Cryptococcus.
antibodies
2026-08-14 | Monoclonal Antibody-Based Anti-Cryptococcosis Therapy.
Cryptococcosis remains one of the most severe invasive fungal diseases worldwide, causing high morbidity and mortality, particularly among immunocompromised individuals. Despite the availability of antifungal drugs, current therapeutic regimens are limited by drug toxicity, prolonged treatment, antifungal resistance, biofilm-associated tolerance, and frequent disease relapse, highlighting the need for novel therapeutic approaches. Monoclonal antibodies (mAbs) have emerged as promising immunotherapeutic agents because of their ability to specifically target fungal components while modulating host immune responses. This review provides a comprehensive overview of recent advances in monoclonal antibody-based strategies against Cryptococcus spp. Additionally, recent innovations in antibody engineering, including radioimmunotherapy, Fc engineering, nanobody technology, immune checkpoint modulation, and chimeric antigen receptor-(CAR)-based cellular therapies, are highlighted as emerging approaches with the potential to enhance antifungal efficacy and overcome current therapeutic limitations. Finally, we discuss the major challenges associated with the clinical translation of antifungal mAbs, including pharmacokinetic barriers, production costs, limited clinical evidence, and regulatory constraints. Collectively, the available evidence supports mAbs as promising adjunctive immunotherapeutic agents and underscores the importance of continued advances in antibody engineering and clinical research to facilitate their incorporation into future strategies for the treatment of cryptococcosis.
2026-07-06 | Paradoxical Th1 activation and CTLA-4 regulation is beneficial during latent cryptococcosis
ABSTRACT Cryptococcus neoformans is the predominant causative agent of cryptococcal meningitis in immunocompromised individuals. Conversely in immunocompetent individuals, C. neoformans establishes a latent pulmonary infection characterized by a paucity of clinical symptoms. Using a mouse inhalation model of latent C. neoformans infection, we previously showed that CD4 T-cells are necessary for preventing fungal proliferation in the lungs. In the current study, we performed single cell RNA sequencing (scRNAseq) and found that the CD4 T-cell response was both highly heterogenous and dichotomous during pulmonary C. neoformans infection, with concomitant expression of genes related to Th1 polarization ( Tbx21 , Ifng ) and immune regulation ( Ctla4 ). First, we demonstrated that cells with Th1-like phenotypes are necessary and sufficient to control latent infection via adoptive transfer of T-bet positive cells into infection-matched CD4-depleted recipient mice. Second, scRNAseq analysis revealed the subpopulation of effector CD4 T-cells that co-expressed Ctla4 and Gata3 was significantly higher than a subpopulation that co-expressed Ctla4 and Tbx21 . Furthermore, our data suggested that CTLA-4 upregulation is beneficial against C. neoformans infection, as CTLA-4 blockade promoted fungal proliferation. Thus, we propose a model wherein Th1 control of latent C. neoformans infection is supported by CTLA-4 suppression of detrimental Th2 activation. IMPORTANCE CD4 T-cells are a critical part of the adaptive immune response in many infections. Upon inhalation of the fungal pathogen Cryptococcus neoformans , CD4 T-cells are necessary to control the initial latent infection and prevent disease. In immunocompromised individuals that lack CD4 T-cells, the initial infection in the lungs can spread to the brain and cause lethal meningitis. In this study, we show that the CD4 T-cells present during latent C. neoformans infection are heterogeneous with expression of diverse polarization and immune regulation markers that function in concert to prevent disease. Our studies highlight the previously unappreciated diversity and complex regulation of the CD4 T-cell response that is required to prevent disease in this important fungal pathogen.
2026-06-29 | Data and code from: Paradoxical Th1 activation and CTLA-4 exhaustion is beneficial during latent cryptococcosis
Cryptococcus neoformans is the predominant causative agent of cryptococcal meningitis in immunocompromised individuals. Conversely, in immunocompromised individuals, C. neoformans establishes a latent pulmonary infection characterized by a paucity of clinical symptoms. Using a mouse inhalation model of latent C. neoformans infection, we previously showed that CD4 T-cells are necessary for preventing lung proliferation. In the current study, we performed unbiased single-cell RNA sequencing (scRNAseq) and found that the CD4 T-cell response was both highly heterogeneous and dichotomous during pulmonary C. neoformans infection, with concomitant expression of genes related to Th1 polarization (Tbx21, Ifng) and immune exhaustion (Ctla4). First, we demonstrated that cells with Th1-like phenotypes are necessary and sufficient to control latent infection via adoptive transfer of T-bet-positive cells into infection-matched CD4-depleted recipient mice. Second, scRNAseq analysis revealed that the subpopulation of effector CD4 T-cells that co-expressed Ctla4 and Gata3 was significantly higher than the subpopulation that co-expressed Ctla4 and Tbx21. Furthermore, our data suggested that CTLA-4 upregulation is beneficial and immunosuppressive against C. neoformans infection, as CTLA-4 blockade promoted fungal proliferation. Thus, we propose a model wherein Th1 control of latent C. neoformans infection is supported by CTLA-4 suppression of Th2 activation.
2026-06-22 | TREM2 drives monocyte-derived macrophage responses to Cryptococcus neoformans.
Cryptococcus neoformans is an opportunistic fungus that causes pulmonary and central nervous system infections after entry into the lungs. We previously established that signaling through the adapter protein DAP12 inhibits the antifungal response of monocyte-derived macrophages and worsens the survival of mice after C. neoformans infection. However, the molecular mechanisms by which DAP12 signaling is initiated during cryptococcosis remain inadequately characterized. In this study, we identify triggering receptor expressed on myeloid cells 2 (TREM2) as a DAP12-associated receptor that is induced on murine monocytes and interstitial macrophages in the lungs in response to C. neoformans infection. TREM2 subsequently represses fungal uptake and M1 polarization by monocyte-derived macrophages. Using an in vitro binding assay, we find that both murine and human TREM2 can directly bind to C. neoformans and that the absence of the cryptococcal cell wall antigen β-1,6-glucan disrupts these interactions. Overall, our findings suggest that the TREM2-DAP12 pathway plays an important inhibitory role in the host immune response to cryptococcal infection by impeding macrophage activation and phagocytosis of fungal cells. We also establish TREM2 as a receptor involved in direct fungal sensing of C. neoformans .
2026-03-01 | CASE REPORT OF PRIMARY CUTANEOUS CRYPTOCOCCOSIS ASSOCIATED WITH SECUKINUMAB USE (IL-17A INHIBITOR)
Primary cutaneous cryptococcosis (PCC) is a rare clinical entity characterized by direct skin infection by Cryptococcus spp., usually after local trauma, without evidence of systemic dissemination or prior pulmonary involvement. Typically, cutaneous manifestations of cryptococcosis result from hematogenous dissemination in immunosuppressed individuals, especially those with HIV/AIDS, transplant recipients, or patients using immunosuppressive drugs. PCC, however, is rarely reported in the literature, particularly in patients undergoing immunobiological therapy. This case involves a 33-year-old man with psoriasis and primary sclerosing cholangitis with liver cirrhosis, receiving monthly secukinumab (a monoclonal antibody IL-17A inhibitor), who developed a cutaneous ulcer on the left forearm after trauma from a wooden pallet. The condition evolved without systemic symptoms or abnormalities in routine laboratory tests. Biopsy and culture of the lesion revealed Cryptococcus gattii. No evidence of systemic or pulmonary fungal infection was found. Treatment consisted of amphotericin B deoxycholate and fluconazole for 14 days, followed by maintenance fluconazole, with clinical improvement and lesion healing. However, two months after discharge, the patient developed severe infection and septic shock due to Staphylococcus aureus bacteremia, resulting in death. The association between PCC and secukinumab use is noteworthy, as there are no previous reports of primary cutaneous cryptococcosis in patients receiving IL-17 inhibition. Secukinumab, approved for psoriasis and spondyloarthropathies, has mucocutaneous candidiasis and other superficial fungal infections described as adverse events, without strong evidence of Cryptococcus spp. infections. IL-17A plays a crucial role in barrier immunity against fungi, and its inhibition may predispose patients to uncommon infections, as illustrated in this case. This report expands the spectrum of opportunistic infections associated with IL-17 inhibitors and suggests the need for close monitoring for atypical fungal infections in patients receiving these therapies, particularly those with additional immunosuppressive comorbidities. The case highlights the importance of early diagnosis and appropriate management of opportunistic infections in immunosuppressed patients and underscores the relevance of reporting similar cases to support future clinical recommendations.
other
2026-09-13 | Pulmonary cryptococcosis with or without immunocompromise: a retrospective comparative study of clinical and CT features and influential factors for lesion absorption.
Pulmonary cryptococcosis (PC) is an invasive fungal infection with rising incidence in immunocompetent populations. The differential clinical and imaging characteristics between immunocompromised (ICP) and non-immunocompromised (NICP) patients remain incompletely characterized, limiting precision in diagnosis and management. A retrospective study was conducted on 117 patients with confirmed PC from a single tertiary center. Patients were stratified into ICP and NICP groups based on refined criteria. Clinical symptoms, laboratory findings, and chest CT imaging features were systematically compared. Quantitative volumetric analysis was performed on follow-up CT scans (n = 31) to calculate the degree of absorption (DOA). LASSO regression was used for exploratory prognostic factor analysis. A high proportion of patients (59.0%) were asymptomatic at presentation. After False Discovery Rate (FDR) correction, no significant differences in clinical symptoms were found between ICP and NICP groups. Laboratory profiles, however, provided objective differentiation, with ICP patients showing significantly lower red blood cell counts and albumin levels (all Q < 0.05). CT imaging revealed that solitary nodules (Type I) were more common in NICP patients (Q = 0.030), while complex patterns like patchy consolidation (Type III) and numerous lesions (≥10) were significantly associated with ICP status (Q = 0.035). The halo sign was not a robust differentiator after FDR correction (Q = 0.105). Serum CrAg testing showed high diagnostic accuracy (83.9% positivity). In follow-up, a significantly lower DOA was observed in ICP patients (75.1% vs. 86.7%, P = 0.038). The conservative LASSO model identified no robust predictors of DOA, but an exploratory analysis nominated imaging type, immune status, and treatment duration as candidate factors. The clinical presentation of PC is non-specific and cannot reliably differentiate immune status, underscoring the necessity of integrated laboratory and radiographic evaluation. ICP patients present with distinct laboratory abnormalities and more complex imaging patterns. Treatment response assessment should combine clinical, radiographic, and serological trends, as antigen persistence is common. From a clinical perspective, population-based screening is not recommended given the high proportion of incidentally discovered cases; instead, diagnostic vigilance during routine imaging should be emphasized. In immunocompetent patients with small solitary lesions, surgery alone represents an effective option that can reduce the need for prolonged antifungal therapy. Larger prospective studies are needed to validate the exploratory prognostic factors identified.
2026-02-28 | Strain-specific variation in virulence and host-immune modulation across the Cryptococcus gattii species complex.
Cryptococcus gattii is an environmental yeast capable of causing severe infections in immunocompetent hosts. Its virulence mechanisms remain less characterized than those of C. neoformans. This study aimed to evaluate the expression of major virulence factors and the immunomodulatory potential of eight C. gattii strains representing five genotypes and multiple sequence types (STs). Virulence traits-including capsule thickness, melanin and laccase production, phospholipase, hemolysin, urease, and DNase activities-were assessed using standardized in vitro assays. In vivo pathogenicity was evaluated in Galleria mellonella, and macrophage responses were analyzed via nitric oxide (NO) production and cytokine gene expression in J774.A1 cells. Capsule and melanin production varied significantly across strains, with VGI/ST106 and VGII/ST7 showing the highest levels, respectively. VGIV/ST336, VGI/ST106, and VGVI/ST556 induced greater larval mortality than the reference C. neoformans strain (VNI/ST5), while VGII strains exhibited ST-dependent virulence. Most strains inhibited NO production in macrophages, except VGI/ST106, which enhanced it. Cytokine expression remained low in the absence of inflammatory priming. These findings reveal substantial phenotypic variability in virulence and immune modulation among C. gattii strains. Further investigation into strain-specific host interactions may helpthe development of targeted antifungal strategies and improve clinical management of cryptococcosis.
2026-02-25 | An integrative ultrastructural and transcriptomic analysis of host-pathogen interactions with human brain microvascular endothelial cells during cryptococcal infection: a preliminary study.
In humans, Cryptococcus neoformans and Cryptococcus gattii species complexes are the leading cause of fungal meningitis globally. To establish CNS infection, Cryptococcus must breach the BBB, primarily comprised of specialized brain microvascular endothelial cells (BMECs), which is the prerequisite for cryptococci to invade the brain. Despite its clinical impact, the mechanisms underlying host-pathogen interaction at the BBB particularly involving environmental isolates remain under-characterized. This study aimed to investigate the cyto-morphological and transcriptomic responses of HBMECs to infection by clinical and environmental Cryptococcus isolates using a dual approach-ultrastructural electron microscopy and high-throughput dual RNA-Seq. HBMECs were infected in vitro with molecularly typed clinical and environmental isolates of C. neoformans and C. gattii at two infection time points (4 hpi and 18 hpi). Transmission electron microscopy was used to visualize host cell ultrastructural alterations, while dual RNA-Seq was performed to assess differential gene expression in both host and pathogen. TEM revealed extensive ultrastructural changes in infected HBMECs, including membrane ruffling, increased microvilli, mitochondrial alterations, ER dilation, Golgi fragmentation, nuclear deformation, and autophagosome formation. Transcriptomic profiling demonstrated functional enrichment of several critical cryptococcal virulence-associated genes linked to immune evasion and stress adaptation including various immune signaling pathways elicited by the HBMECs as a counter measure to the cryptococcal invasion. Clinical and environmental Cryptococcus isolates exhibit comparable invasive potential and elicit similar host endothelial responses with consistent effects observed across all isolates and time points. This integrative study combining ultrastructural and transcriptomic analyses highlights conserved host-pathogen interactions at the BBB, identifies potential molecular targets for antifungal therapy and underscores the pathogenic relevance of environmental reservoirs in cryptococcal meningitis. cryptococcal meningitis, blood-brain barrier, invasion, transmission electron microscopy, Dual RNASeq, differential gene expression, host-pathogen interaction, HBMECs, ultrastructural alterations.
2025-12-17 | The catalase gene CAT2 and its role in the virulence of one sub-cluster of Cryptococcus gattii VGI clinical isolates.
Cryptococcus gattii causes cryptococcosis and life-threatening cryptococcal meningitis. Currently, the pathogenic virulence mechanisms of C. gattii remain a significant area of ongoing research with considerable unexplored aspects. On the basis of our established research, a sub-cluster of strains with independent evolutionary relationships from WM276 in the phylogenetic analysis of VGI-type strains is identified. In vivo infection experiments on this sub-branch of strains reveal that there are hypervirulent strains and hypovirulent strains among these strains, and the virulence differences are significant ( P < 0.001). Bioinformatic interrogation of differentially expressed genes reveals that the catalase-encoding gene CGB_J0620W, CAT2, is a pivotal virulence-associated gene. The hypervirulent clinical isolate G4 (G4-WT) is selected as the parental strain, from which an isogenic CAT2-knockout mutant ( cat2Δ) is constructed via homologous recombination, which shows increased sensitivity to oxidative stress, as well as growth defects in response to hyperosmosis, 5-fluorocytosine, fluconazole and amphotericin B. The cat2Δ::CAT2 strain exhibits phenotypic restoration to wild type (WT). In the mouse experiments, significant differences in survival ( P < 0.001), pulmonary fungal burden ( P < 0.01), and alveolar structural damage are observed between the WT and cat2Δ strains, which are completely different from C. neoformans. Moreover, comparative transcriptome analysis is performed on the WT and cat2Δ strains, which reveals that enzymes encoded by CAT2 may be involved in oxidative stress, metabolism and sugar transport. In conclusion, this study may explain the differences in virulence among different genetic evolutionary processes of a sub-cluster of the VGI geneotype of C. gattii and provide a theoretical basis for targeted therapy in a specific genotype population in the future.
2025-07-21 | Identification of ATM1 gene involved in antifungal resistance based on CRISPR/Cas9 technology in Cryptococcus gattii.
Cryptococcus gattii is a fungal pathogen that poses significant threats to human health, affecting both immunocompromised and immunocompetent individuals. Treatment of C. gattii infections typically involves the use of antifungal agents, such as azoles. However, the increasing emergence of antifungal resistance in C. gattii is a growing concern, highlighting the critical need for novel therapeutic strategies. In our previous study, we identified a mitochondrial ATP-binding cassette (ABC) transporter, Atm1, as potentially involved in antifungal resistance in C. gattii through transcriptome sequencing, but its function remains unclear and requires additional confirmation and investigation. In this study, we developed a "suicide" clustered regularlyinterspaced short palindromic repeats-CRISPR-associated protein 9 system in C. gattii, based on the system used in C. neoformans, and successfully validated its functionality by targeting the ADE2 gene. We subsequently generated C. gattii mutants lacking ATM1 and assessed their growth under various stress conditions. Our data suggest that Atm1 is involved in the iron-sulfur cluster biosynthesis process. Besides, disruption of ATM1 resulted in various growth impairments, including reduced stress tolerance, impaired capsule formation, and diminished virulence. Importantly, we observed compromised antifungal drug resistance in the atm1∆ mutant and performed RNA sequencing-based transcriptome analysis and gene ontology analysis with and without antifungal treatment for further investigation. In conclusion, our findings indicate that ATM1 plays a role in iron homeostasis and is critical for antifungal resistance in C. gattii, offering new insights into potential drug development strategies for the clinical treatment of cryptococcosis.
small molecules
2026-09-30 | Molecular types, clinical profile, and exploratory virulence-associated phenotypes of clinical Cryptococcus isolates from Amazonas, Brazil.
Cryptococcosis remains a severe systemic mycosis, especially among people living with HIV/AIDS, and culture-based molecular data from Amazonas remain limited. The aim was to identify which Cryptococcus molecular types circulated among clinical isolates from Amazonas between 2020 and 2024; what were the main clinical characteristics and outcomes of patients infected with Cryptococcus neoformans molecular type VNI and Cryptococcus gattii molecular type VGII; and whether these molecular types differed in selected susceptibility-related and virulence-associated phenotypes. We analyzed 70 culture-confirmed clinical isolates from patients treated at the Dr. Heitor Vieira Dourado Tropical Medicine Foundation, Manaus, Brazil. Molecular types were assigned by URA5 PCR-RFLP using reference strains. Demographic and clinical variables were retrieved from medical records. A stratified 30-isolate subset comprising 24 VNI and 6 VGII isolates was evaluated for phospholipase activity and melanization. Fluconazole MICs were analyzed for the complete 70-isolate dataset and were determined by broth microdilution according to CLSI M27-A4. VNI predominated (64/70; 91.4%), whereas VGII accounted for 6/70 isolates (8.6%). The series was predominantly composed of men, young adults, and HIV-positive patients. HIV infection was more frequent among VNI cases, whereas VGII included proportionally more HIV-negative patients. In-hospital death occurred in 17/70 patients (24.3%). Fluconazole MICs, phospholipase activity, and melanization were broadly comparable between VNI and VGII, although the small VGII subgroup precluded robust genotype-associated inference. VNI was the dominant molecular type in this severe reference-center cryptococcosis series from Amazonas. Phenotypic findings should be interpreted as exploratory and hypothesis-generating.
2026-09-03 | Discovery of Novel Ligands for the Treatment of Cryptococcus neoformans Infection.
Fungal pathogens are an escalating global public health concern, particularly in the context of invasive and opportunistic infections. Cryptococcosis, primarily caused by Cryptococcus neoformans var. grubii, can affect multiple organs and often leads to life-threatening meningitis in immunocompromised individuals. Given limited antifungal therapies and emergence of resistance and toxicity-related constraints, the development of novel anti-cryptococcal agents remains an urgent priority. A library of innovative 3-hydroxypyridin-4(1H)-one-based hybrids (5a-f) was synthesized and evaluated for antimicrobial activity against clinically relevant Gram-positive and Gram-negative bacteria, as well as fungal species Candida albicans and C. neoformans var. grubbi. Safety was assessed through cytotoxicity studies in HEK293 and HepG2 cells and hemolytic evaluation, while iron-chelating capacity and lipophilicity were also investigated. All compounds formed stable iron(III) complexes and displayed no significant toxicity up to 25 μM. Series 1 compounds (5a-c) were less lipophilic than Series 2 (5d-f), mainly due to regioisomeric position of hydroxyl group on 2-methyl-4-pyridone scaffold, whereas fluorination increased lipophilicity in both series. Notably, compounds 5c-f emerged as potent, selective, and nontoxic antifungal agents against C. neoformans var. grubii (MIC < 16 µg/mL; CC50 > 32 µg/mL; HC10 > 32 µg/mL), highlighting the potential of 3-hydroxypyridin-4(1H)-one-based hybrids as a promising approach for cryptococcal meningitis therapy.
2026-09-01 | Pulmonary Cryptococcosis in an Immunocompetent Young Adult Male : A Case Report
Cryptococcosis mainly affects immunocompromised hosts but can also occur in immunocompetent individuals, often presenting with non-specific pulmonary radiological lesions and asymptomatic clinical course, which frequently causes misdiagnosis and delayed treatment. Diagnostic challenges arise when central nervous system (CNS) involvement is suspected despite negative initial cerebrospinal fluid (CSF) microscopy findings. We present a 24-year-old previously healthy immunocompetent male with incidental left lung infection detected on chest CT, who remained completely asymptomatic. Empirical oral antibiotic treatment resulted in only minimal improvement of lung lesions. Laboratory tests showed positive serum cryptococcal polysaccharide antigen. Bronchoalveolar lavage mNGS detected Pneumocystis jirovecii and Klebsiella aerogenes, with elevated BAL galactomannan level. Lumbar puncture revealed elevated CSF protein, neutrophil-predominant pleocytosis and weakly positive Pandy’s test, while India ink staining and culture were negative for cryptococci. The patient had normal CD4 count, confirming intact immune function. Induction therapy with liposomal amphotericin B plus flucytosine was initiated for presumed cryptococcal meningoencephalitis. Transient liver enzyme elevation and hypokalemia occurred during treatment, which were effectively corrected by symptomatic management, and the patient was discharged in stable condition. This case indicates that positive serum cryptococcal antigen in patients with pulmonary nodules requires mandatory CNS evaluation even without typical meningeal symptoms. Negative CSF India ink cannot exclude cryptococcal meningitis. Incidental detection of Pneumocystis jirovecii by mNGS in immunocompetent individuals raises concerns about colonization or subclinical infection. Clinicians should interpret mNGS results cautiously and determine the true pathogen based on comprehensive clinical information. Pulmonary cryptococcosis should be considered for persistent unexplained pulmonary lesions regardless of immune status; early serological screening, routine lumbar puncture to rule out occult CNS dissemination, and timely standardized antifungal therapy are essential to improve diagnostic accuracy and clinical prognosis.
2026-08-27 | Synergic Effect of Fluconazole and Quinoline Derivatives Combination Against Cryptococcus spp., Mechanisms of Action and Toxicity.
Cryptococcosis is a severe fungal infection affecting immunocompromised individuals, with treatment limited to FLZ, AMB, and FC. This study investigated the antifungal potential of fluconazole (FLZ)-, amphotericin B (AMB)-, 8-hydroxyquinoline (8HQ)-, and clioquinol (CQ)-based combinations against Cryptococcus neoformans and C. gattii. Drug interactions were assessed by checkerboard assay, followed by time-kill curves, irritability, toxicity, and virulence factors inhibition tests. The FLZ + AMB combination showed weak synergism, whereas FLZ combined with CQ or 8HQ exhibited strong synergistic effects (p < 0.001) at low concentrations (0.125-0.25 µg/mL), up to three times greater than those of FLZ + AMB. This effect persisted across other strains, including less FLZ-susceptible isolates. Moreover, FLZ + CQ inhibited melanin production in both species without causing significant irritability or toxicity in the tested models. These results indicate that combining drugs with distinct mechanisms of action can enhance antifungal efficacy while potentially reducing treatment doses. The FLZ + CQ/8HQ combinations represent promising candidates for future in vivo models for therapeutic evaluation.
2026-08-17 | Investigating the therapeutic potential of the antibacterial drug nitroxoline in combating cryptococcal infection.
Cryptococcosis is a major health threat among immunocompromised individuals, resulting in life-threatening consequences secondary to brain invasion. The limited treatment options and the increased incidence of treatment failure and relapses urge the need for more effective therapies. In this study, we investigated the therapeutic potential of nitroxoline (NTX) in treating cryptococcal infection. NTX exhibited potent fungicidal activity against Cryptococcus neoformans/gattii clinical isolates, with an MIC90 of 1 µg/mL. In addition, NTX substantially inhibits the main virulence traits of cryptococcal cells, including the polysaccharide capsule, melanin production, and the urease enzyme, which are crucial for the infection progression. In exploring the potential mechanism of action, our results revealed the relationship between the metal-chelating properties of the NTX scaffold and its antifungal activity. Interfering metal chelation, either through structural modification or exogenous supplementation with varied divalent cations, significantly reduced the antifungal and anti-virulence activities of NTX. Given its potential therapeutic role, we evaluated the interaction between NTX and the clinically used antifungals amphotericin B, flucytosine and fluconazole. Additionally, we investigated the tendency of cryptococcal cells to develop resistance following repeated exposure to NTX, as well as its efficacy in the Caenorhabditis elegans nematode model of cryptococcal infection. Notably, cryptococcal cells exhibited consistent susceptibility to NTX upon repeated exposure to a subinhibitory concentration. In the C. elegans model, NTX significantly reduced the fungal burden of the infected worms, achieving a 2-log10 reduction, and consistently enhanced their survival compared to untreated group. These findings highlight the potential role of the NTX scaffold in combating cryptococcal infection that warrants further investigation.
vaccines
2026-09-24 | A protective hybrid protein vaccine informed by mapping major histocompatibility class II epitopes in Cryptococcus neoformans chitin deacetylases that stimulate CD4 + T cell responses.
Infections due to Cryptococcus species are estimated to cause over 100,000 deaths a year. No cryptococcal vaccines are approved for human use. We have shown that vaccine formulations consisting of C. neoformans chitin deacetylase (Cda)2 and Cda1 adjuvanted with Cationic Adjuvant Formulation 01 (CAF01) protect mice against experimental cryptococcosis by a mechanism dependent upon CD4 + T cells. Here, using overlapping peptide libraries, we mapped epitopes in Cda2 and Cda1 that stimulated interferon-gamma (IFNγ) release from splenocytes of C57BL/6 and DR4 mice immunized with these proteins. DR4 mice lack mouse major histocompatibility class II (MHC-II) proteins and express chimeric MHC-II proteins with the specificity of the human HLA-DR allele, HLA-DRB1*04:01. Experimental results were then compared with MHC-II binding predictions using the Immune Epitope Database (IEDB) NetMHCIIpan 4.1 BA MHC-II epitope prediction tool. Unique epitopes in Cda2 and Cda1 were discovered for each mouse strain, some of which were not predicted to bind well to MHC-II. CD4 + T cells were responsible for cytokine release as IFNγ production was lost if CD4 + T cells were depleted from the splenocyte population. Finally, we tested a hybrid recombinant protein that consisted of portions of Cda2 and Cda1 containing the MHC-II/CD4 + T cell epitopes which induce CD4 + T cells in DR4 mice. When administered as a CAF01-adjuvanted vaccine, the hybrid protein protected DR4 mice from an otherwise lethal C. neoformans pulmonary challenge. These results provide a proof of principle regarding the utility of MHC-II/CD4 + T cell epitope mapping in cryptococcal vaccine development. The development of vaccines to prevent cryptococcosis, a fungal disease which causes over 100,000 deaths annually, is a public health priority. We have demonstrated that adjuvanted vaccines containing two Cryptococcus neoformans protein antigens, chitin deacetylase (Cda)2 and Cda1, protect mice against experimental cryptococcosis by a mechanism dependent upon CD4 + T cells. In this study, we determined which 15 amino acid peptides of Cda2 and Cda1 stimulate CD4 + T cells in C57BL/6 and DR4 mice; the latter mouse strain has human major histocompatibility class II (MHCII) specificity. We then synthesized a small hybrid protein containing those portions of Cda2 and Cda1 that strongly stimulated CD4 + T cell responses in DR4 mice. As an adjuvanted vaccine, the hybrid Cda2/1 protein protected DR4 mice from a C. neoformans pulmonary challenge. Thus, CD4 + T cell/MHCII epitope mapping experimentally validated the design of a protective multi-epitope protein for use in cryptococcal vaccines.
2026-06-17 | Systematic infectome-phenome profiling reveals cryptococcal infection-associated proteins driving immune system remodeling and immunization potential.
Invasive fungal infections are an escalating global health challenge driven by host immune status and antifungal resistance. Here, we present an integrated infectome-phenome platform that combines high-resolution proteomics with systematic phenotypic profiling to map host-pathogen interactions in Cryptococcus neoformans. This approach captures coordinated host immune suppression alongside complementary fungal virulence programs and enables the prioritization of infection-associated proteins. Phenome fingerprinting of targeted mutants resolves functional relevance and therapeutic potential, supported by in vitro assays and a murine model of cryptococcosis. We identify a conserved, previously uncharacterized protein, CipC, that alters extracellular vesicle composition and enhances antigenicity. Immunization with CipC-derived vesicles elicits a robust and diversified host immune response, highlighting a role for fungal vesicles in immune priming. Together, this work establishes a scalable framework to define functional drivers of fungal infection and accelerate discovery of therapeutic and immunological targets across pathogenic fungi.
2026-06-01 | Acetylation and accessibility of Cryptococcus neoformans cell wall chitosans influence the strength of host immune responses.
The fungal pathogen Cryptococcus neoformans causes fatal cryptococcal meningitis, a significant global health risk. Unlike most fungi, C. neoformans expresses chitin deacetylases that convert its cell wall chitin into chitosan, helping to evade chitin-triggered host immunity. However, it is unclear how the properties and accessibility of these chitosans vary between strains and growth conditions, and how they influence the host immune response. To show how chitin deacetylase activity and growth conditions shape the properties of cell wall chitosans, we present the first comprehensive analysis of the chitosan content, fraction of acetylation (FA), enzymatic degradation products by host chitinases, and accessibility in various Cryptococcus strains, including chitin deacetylase mutants, cultivated under different conditions. Certain chitin deacetylase knockouts, as well as challenging growth conditions, lead to higher FAs and enhanced exposure, associated with stronger host immune responses. The response to cryptococcal chitin/chitosan ranges from low (resulting in cryptococcosis) to adequate (providing effective host defense) and excessive (leading to hyper-inflammation). Correlation between the strength of the immune response and the abundance of chitin-binding proteins was used to rapidly screen a multitude of strains and growth conditions for their immunogenic potential. Our approach provides insight into Cryptococcus-related disease caused by insufficient and excessive immune responses, and may accelerate the development of effective cell-based vaccines.
2026-03-10 | mGem: Progress on the development of conjugate vaccines for Cryptococcus neoformans infections.
Cryptococcus neoformans is an important fungal pathogen that causes cryptococcosis, a life-threatening disease predominantly affecting immunocompromised individuals. Current estimates suggest that cryptococcosis is responsible for over 150,000 deaths annually, highlighting the need for the development of effective preventive measures. Early research utilizing polysaccharide filtrates (CneF) laid the groundwork for polysaccharide-containing vaccines, demonstrating partial protection in murine infection models. Further vaccine constructs made with purified extracellular polysaccharides (EPS) conjugated to protein carriers elicited strong antibody responses and enhanced survival. Recently, more attention was given to the purified capsule components glucuronoxylomannan (GXM) and glucuronoxylomannogalactan (GXMGal), with studies indicating that GXM conjugates can elicit protective effects. The development of semisynthetic polysaccharide-based vaccines offers a new approach to addressing lot-to-lot variability, enhancing consistency. In conclusion, strategies that advance from early crude formulations to more sophisticated conjugate and synthetic vaccines hold great promise for developing an effective vaccine to prevent and treat cryptococcal diseases.
2025-12-24 | Vaccine-Mediated Protection of Mice Against African and Asian Clinical Strains of Cryptococcus neoformans.
Infections with strains of the Cryptococcus neoformans species complex are responsible for over 100,000 deaths per year, predominantly due to meningitis in immunocompromised individuals. Despite much research, there are no licensed fungal vaccines available. Most experimental cryptococcal vaccine formulations have been tested in preclinical models using laboratory strains of C. neoformans, particularly H99 and KN99. However, to be effective, vaccines need to protect against the wide variety of cryptococcal isolates found worldwide, particularly in regions that have the highest burden of infections. Therefore, we explored vaccine-mediated protection of BALB/c mice against experimental cryptococcosis due to six C. neoformans strains originally isolated from patients with cryptococcal meningitis in Vietnam, Uganda, and Botswana. Two vaccines were tested: a live-attenuated C. neoformans vaccine lacking three chitin deacetylase genes, and a quadrivalent subunit protein vaccine adjuvanted with Cationic Adjuvant Formulation 01. When compared to unvaccinated mice, both vaccines provided significant protection against all six clinical strains. However, the degree of protection varied as a function of vaccine formulation and clinical strain. Lung leukocytes from vaccinated and infected mice had significantly increased antigen-stimulated interferon-gamma production compared with infected but unvaccinated mice. Thus, although the degree of protection varied, two cryptococcal vaccines significantly protected mice against experimental infection with cryptococcal strains representative of regions of the world that account for the majority of cryptococcal meningitis cases found globally. These data provide preclinical support for trialing vaccines in persons at high risk for developing cryptococcosis.
proteins
2026-09-11 | New approaches for cryptococcosis treatment and prevention-a systematic review.
Cryptococcosis remains a life-threatening fungal infection with high mortality despite current antifungal therapy. The toxicity, limited accessibility, poor tissue penetration, and increasing resistance associated with conventional antifungals highlight the need for innovative preventive and therapeutic strategies. This systematic review summarises recent advances in cryptococcosis management and identifies priorities for future research and clinical translation. PubMed, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov were systematically searched for studies published between January 2005 and December 2025. Data on study characteristics, therapeutic strategies, mechanisms, and outcomes were extracted. Because of substantial heterogeneity among clinical and preclinical studies, quantitative synthesis and certainty-of-evidence assessment were not performed. Eighty-six studies were included. Promising advances were identified in vaccines, immunotherapy, nanotechnology-based drug delivery, novel antifungal agents, drug repurposing, and non-pharmacological interventions. Vaccine candidates induced protective immunity in animal models but remain preclinical. Adjunctive interferon-γ is the only immunotherapy supported by clinical evidence, whereas programmed cell death protein 1 (PD-1) blockade, chimeric antigen receptor T-cell (CART) therapy, most of monoclonal antibodies, and other immunomodulators remain under preclinical investigation. MAT2203 demonstrated non-inferior efficacy with improved safety compared with intravenous amphotericin B. Several novel antifungal agents have entered clinical development, whereas repurposed drugs have shown limited clinical benefit. Most non-pharmacological approaches also remain experimental. Emerging strategies are reshaping cryptococcosis management beyond conventional antifungal therapy. Although most remain at the preclinical or early clinical stage, advances in host-directed immunotherapy, nanomedicine, and novel antifungal development provide promising opportunities to improve treatment efficacy, safety, and accessibility. Well-designed clinical studies are needed to facilitate clinical translation.
2026-08-17 | Temporal shifts in adaptive immunity drive HIV-associated cryptococcal IRIS: mechanisms, models, and therapeutic opportunities.
Cryptococcal meningoencephalitis (CME) remains a leading cause of AIDS-related mortality, and up to one-quarter of persons living with HIV who survive CME develop cryptococcal immune reconstitution inflammatory syndrome (CME-IRIS) after antiretroviral therapy (ART) initiation. CME-IRIS arises when recovering immunity encounters a high residual fungal antigen burden, yet the temporal adaptive immune dynamics that distinguish protective reconstitution from damaging neuroinflammation are not fully defined. This review synthesizes clinical and experimental data to propose a temporal framework centered on CD4+ T cell polarization, regulatory failure, memory T cell quality, and T-B cell coordination. Before ART, many patients exhibit a Th2-skewed, low-inflammatory state with impaired Th1 responses, reduced antifungal IgM production, and deficient Tfh-B cell coordination, collectively favoring persistent Cryptococcus neoformans antigen burden. With ART, IL-7-driven T cell recovery, Th17/Treg imbalance, Th1/Th17-biased memory responses, and chemokine-guided trafficking of CXCR3+CCR5+ effector cells into the central nervous system can convert this antigen-rich milieu into fulminant neuroinflammation. We further discuss emerging mouse models that recapitulate unmasking CME-IRIS, the contrasting immune profile of Cryptococcus gattii-associated IRIS as a comparative model, and developing therapeutic strategies that include targeted immunomodulators, cell-based therapies, and vaccines. Finally, we highlight future directions - particularly single-cell and spatial transcriptomic profiling of blood and CSF - to resolve which adaptive immune populations drive neuroinflammation and to validate predictive biomarkers for CME-IRIS. A temporally informed view of adaptive immunity in CME-IRIS may refine ART timing, guide risk stratification, and identify new adjunctive interventions for cryptococcosis and related IRIS syndromes.
2026-07-14 | Sphingomyelin synthase 2 regulates host protection conferred by the administration of Cryptococcus neoformans Δsgl1 strain.
Sphingolipids are fundamental components of the plasma membrane that regulate immune receptor organization and host responses to infection. Here, we identify sphingomyelin synthase 2 (SMS2) as a critical mediator of antifungal host defense against Cryptococcus neoformans. SMS2 deficiency reduces sphingomyelin and increases ceramide levels, altering membrane lipid composition and impairing receptor localization. This is associated with decreased plasma membrane toll-like receptor 2, attenuated signaling, and reduced IL-17A and IFNγ production by γδ T cells. Macrophages lacking SMS2 exhibit impaired phagocytosis, resulting in inefficient clearance of the attenuated C. neoformans Δsgl1 strain. Consequently, SMS2-deficient mice fail to develop effective vaccine-induced protection and show increased susceptibility to secondary infection with WT C. neoformans. Mechanistically, bSMase-driven alterations in SM/ceramide balance are associated with disruption of membrane organization and reduced toll-like receptor 2 and cholera toxin B staining, suggesting that SMS2-dependent sphingomyelin regulation represents a key mechanism linking membrane lipid composition to innate immune signaling, phagocytosis, and antifungal host defense against C. neoformans.
2026-01-16 | Conjugation of a Cryptococcus neoformans-derived metalloprotease to antifungal-loaded PLGA nanoparticles treats neural cryptococcosis in an in vitro model.
Overcoming the blood-brain barrier to deliver therapeutics is a major hurdle in treating diseases of the central nervous system. We engineered 4-arm carboxyl terminated poly(D,L-lactide-co-glycolide) nanoparticles with the fungal metalloprotease Mpr1, an enzyme utilized by the neurotropic pathogen Cryptococcus neoformans (Cn) to cross the blood-brain barrier. Nanoparticles were prepared using a modified single emulsion solvent evaporation technique, and characterized in terms of shape, size, zeta potential, encapsulation efficiency, and toxicity to brain microvascular endothelial cells. Mpr1-functionalized nanoparticles had increased penetration over non-functionalized nanoparticles in an in vitro model of the blood-brain barrier. When encapsulating amphotericin B, a potent antifungal drug, Mpr1-functionalized nanoparticles reduced fungal burden in an in vitro model of neural cryptococcosis. Loaded nanoparticles also had an 8-fold lower minimum inhibitory concentration against Cn and Candida albicans (Ca) compared to unencapsulated amphotericin B. Results indicate that Mpr1-coating of polymeric nanoparticles is a promising strategy to enhance drug delivery to the brain.
2025-09-10 | Acute Toxicity and Genotoxicity of cMoL, a Lectin From Moringa oleifera Seeds With Antifungal Activity Against Cryptococcus Strains.
Coagulant Moringa oleifera lectin (cMoL) is one of the compounds involved in the application of M. oleifera seeds for traditional water treatment methods. The present study highlights the new biotechnological potential of cMoL lectin as an antifungal agent against Cryptococcus neoformans B3501 and H99 and Cryptococcus gattii R265 strains. Acute toxicity and genotoxicity were assessed to provide information on security utilization. The antifungal activity was evaluated using the broth microdilution test, flow cytometry, antibiofilm activity, and synergistic effects with fluconazole. Acute toxicity was determined by administering a single dose of cMoL (200 mg/kg) to female Swiss albino mice and examining the following parameters: water and feed consumption, weight variation, blood hematological and biochemical parameters, serum cytokine levels, and histopathological analyses. Genotoxicity was assessed using comet assay and micronucleus test. cMoL inhibited the growth of all tested isolates, with a minimal inhibitory concentration of 7.5 μg/mL. Flow cytometry data showed that cMoL (7.5 μg/mL) significantly decreased cell viability by promoting necrosis. cMoL was not found to be an antibiofilm agent against Cryptococcus species; however, it acted synergistically with fluconazole against C. neoformans H99. cMoL (200 mg/kg) did not cause animal death or toxicity. No hematological, biochemical, histopathological, or genotoxic effects were observed. These results encourage the exploration of cMoL as a natural and safe antifungal agent against Cryptococcus.
antibodies
2026-08-14 | Monoclonal Antibody-Based Anti-Cryptococcosis Therapy.
Cryptococcosis remains one of the most severe invasive fungal diseases worldwide, causing high morbidity and mortality, particularly among immunocompromised individuals. Despite the availability of antifungal drugs, current therapeutic regimens are limited by drug toxicity, prolonged treatment, antifungal resistance, biofilm-associated tolerance, and frequent disease relapse, highlighting the need for novel therapeutic approaches. Monoclonal antibodies (mAbs) have emerged as promising immunotherapeutic agents because of their ability to specifically target fungal components while modulating host immune responses. This review provides a comprehensive overview of recent advances in monoclonal antibody-based strategies against Cryptococcus spp. Additionally, recent innovations in antibody engineering, including radioimmunotherapy, Fc engineering, nanobody technology, immune checkpoint modulation, and chimeric antigen receptor-(CAR)-based cellular therapies, are highlighted as emerging approaches with the potential to enhance antifungal efficacy and overcome current therapeutic limitations. Finally, we discuss the major challenges associated with the clinical translation of antifungal mAbs, including pharmacokinetic barriers, production costs, limited clinical evidence, and regulatory constraints. Collectively, the available evidence supports mAbs as promising adjunctive immunotherapeutic agents and underscores the importance of continued advances in antibody engineering and clinical research to facilitate their incorporation into future strategies for the treatment of cryptococcosis.
2026-07-06 | Paradoxical Th1 activation and CTLA-4 regulation is beneficial during latent cryptococcosis
ABSTRACT Cryptococcus neoformans is the predominant causative agent of cryptococcal meningitis in immunocompromised individuals. Conversely in immunocompetent individuals, C. neoformans establishes a latent pulmonary infection characterized by a paucity of clinical symptoms. Using a mouse inhalation model of latent C. neoformans infection, we previously showed that CD4 T-cells are necessary for preventing fungal proliferation in the lungs. In the current study, we performed single cell RNA sequencing (scRNAseq) and found that the CD4 T-cell response was both highly heterogenous and dichotomous during pulmonary C. neoformans infection, with concomitant expression of genes related to Th1 polarization ( Tbx21 , Ifng ) and immune regulation ( Ctla4 ). First, we demonstrated that cells with Th1-like phenotypes are necessary and sufficient to control latent infection via adoptive transfer of T-bet positive cells into infection-matched CD4-depleted recipient mice. Second, scRNAseq analysis revealed the subpopulation of effector CD4 T-cells that co-expressed Ctla4 and Gata3 was significantly higher than a subpopulation that co-expressed Ctla4 and Tbx21 . Furthermore, our data suggested that CTLA-4 upregulation is beneficial against C. neoformans infection, as CTLA-4 blockade promoted fungal proliferation. Thus, we propose a model wherein Th1 control of latent C. neoformans infection is supported by CTLA-4 suppression of detrimental Th2 activation. IMPORTANCE CD4 T-cells are a critical part of the adaptive immune response in many infections. Upon inhalation of the fungal pathogen Cryptococcus neoformans , CD4 T-cells are necessary to control the initial latent infection and prevent disease. In immunocompromised individuals that lack CD4 T-cells, the initial infection in the lungs can spread to the brain and cause lethal meningitis. In this study, we show that the CD4 T-cells present during latent C. neoformans infection are heterogeneous with expression of diverse polarization and immune regulation markers that function in concert to prevent disease. Our studies highlight the previously unappreciated diversity and complex regulation of the CD4 T-cell response that is required to prevent disease in this important fungal pathogen.
2026-06-29 | Data and code from: Paradoxical Th1 activation and CTLA-4 exhaustion is beneficial during latent cryptococcosis
Cryptococcus neoformans is the predominant causative agent of cryptococcal meningitis in immunocompromised individuals. Conversely, in immunocompromised individuals, C. neoformans establishes a latent pulmonary infection characterized by a paucity of clinical symptoms. Using a mouse inhalation model of latent C. neoformans infection, we previously showed that CD4 T-cells are necessary for preventing lung proliferation. In the current study, we performed unbiased single-cell RNA sequencing (scRNAseq) and found that the CD4 T-cell response was both highly heterogeneous and dichotomous during pulmonary C. neoformans infection, with concomitant expression of genes related to Th1 polarization (Tbx21, Ifng) and immune exhaustion (Ctla4). First, we demonstrated that cells with Th1-like phenotypes are necessary and sufficient to control latent infection via adoptive transfer of T-bet-positive cells into infection-matched CD4-depleted recipient mice. Second, scRNAseq analysis revealed that the subpopulation of effector CD4 T-cells that co-expressed Ctla4 and Gata3 was significantly higher than the subpopulation that co-expressed Ctla4 and Tbx21. Furthermore, our data suggested that CTLA-4 upregulation is beneficial and immunosuppressive against C. neoformans infection, as CTLA-4 blockade promoted fungal proliferation. Thus, we propose a model wherein Th1 control of latent C. neoformans infection is supported by CTLA-4 suppression of Th2 activation.
2026-06-22 | TREM2 drives monocyte-derived macrophage responses to Cryptococcus neoformans.
Cryptococcus neoformans is an opportunistic fungus that causes pulmonary and central nervous system infections after entry into the lungs. We previously established that signaling through the adapter protein DAP12 inhibits the antifungal response of monocyte-derived macrophages and worsens the survival of mice after C. neoformans infection. However, the molecular mechanisms by which DAP12 signaling is initiated during cryptococcosis remain inadequately characterized. In this study, we identify triggering receptor expressed on myeloid cells 2 (TREM2) as a DAP12-associated receptor that is induced on murine monocytes and interstitial macrophages in the lungs in response to C. neoformans infection. TREM2 subsequently represses fungal uptake and M1 polarization by monocyte-derived macrophages. Using an in vitro binding assay, we find that both murine and human TREM2 can directly bind to C. neoformans and that the absence of the cryptococcal cell wall antigen β-1,6-glucan disrupts these interactions. Overall, our findings suggest that the TREM2-DAP12 pathway plays an important inhibitory role in the host immune response to cryptococcal infection by impeding macrophage activation and phagocytosis of fungal cells. We also establish TREM2 as a receptor involved in direct fungal sensing of C. neoformans .
2026-03-01 | CASE REPORT OF PRIMARY CUTANEOUS CRYPTOCOCCOSIS ASSOCIATED WITH SECUKINUMAB USE (IL-17A INHIBITOR)
Primary cutaneous cryptococcosis (PCC) is a rare clinical entity characterized by direct skin infection by Cryptococcus spp., usually after local trauma, without evidence of systemic dissemination or prior pulmonary involvement. Typically, cutaneous manifestations of cryptococcosis result from hematogenous dissemination in immunosuppressed individuals, especially those with HIV/AIDS, transplant recipients, or patients using immunosuppressive drugs. PCC, however, is rarely reported in the literature, particularly in patients undergoing immunobiological therapy. This case involves a 33-year-old man with psoriasis and primary sclerosing cholangitis with liver cirrhosis, receiving monthly secukinumab (a monoclonal antibody IL-17A inhibitor), who developed a cutaneous ulcer on the left forearm after trauma from a wooden pallet. The condition evolved without systemic symptoms or abnormalities in routine laboratory tests. Biopsy and culture of the lesion revealed Cryptococcus gattii. No evidence of systemic or pulmonary fungal infection was found. Treatment consisted of amphotericin B deoxycholate and fluconazole for 14 days, followed by maintenance fluconazole, with clinical improvement and lesion healing. However, two months after discharge, the patient developed severe infection and septic shock due to Staphylococcus aureus bacteremia, resulting in death. The association between PCC and secukinumab use is noteworthy, as there are no previous reports of primary cutaneous cryptococcosis in patients receiving IL-17 inhibition. Secukinumab, approved for psoriasis and spondyloarthropathies, has mucocutaneous candidiasis and other superficial fungal infections described as adverse events, without strong evidence of Cryptococcus spp. infections. IL-17A plays a crucial role in barrier immunity against fungi, and its inhibition may predispose patients to uncommon infections, as illustrated in this case. This report expands the spectrum of opportunistic infections associated with IL-17 inhibitors and suggests the need for close monitoring for atypical fungal infections in patients receiving these therapies, particularly those with additional immunosuppressive comorbidities. The case highlights the importance of early diagnosis and appropriate management of opportunistic infections in immunosuppressed patients and underscores the relevance of reporting similar cases to support future clinical recommendations.
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2026-09-13 | Pulmonary cryptococcosis with or without immunocompromise: a retrospective comparative study of clinical and CT features and influential factors for lesion absorption.
Pulmonary cryptococcosis (PC) is an invasive fungal infection with rising incidence in immunocompetent populations. The differential clinical and imaging characteristics between immunocompromised (ICP) and non-immunocompromised (NICP) patients remain incompletely characterized, limiting precision in diagnosis and management. A retrospective study was conducted on 117 patients with confirmed PC from a single tertiary center. Patients were stratified into ICP and NICP groups based on refined criteria. Clinical symptoms, laboratory findings, and chest CT imaging features were systematically compared. Quantitative volumetric analysis was performed on follow-up CT scans (n = 31) to calculate the degree of absorption (DOA). LASSO regression was used for exploratory prognostic factor analysis. A high proportion of patients (59.0%) were asymptomatic at presentation. After False Discovery Rate (FDR) correction, no significant differences in clinical symptoms were found between ICP and NICP groups. Laboratory profiles, however, provided objective differentiation, with ICP patients showing significantly lower red blood cell counts and albumin levels (all Q < 0.05). CT imaging revealed that solitary nodules (Type I) were more common in NICP patients (Q = 0.030), while complex patterns like patchy consolidation (Type III) and numerous lesions (≥10) were significantly associated with ICP status (Q = 0.035). The halo sign was not a robust differentiator after FDR correction (Q = 0.105). Serum CrAg testing showed high diagnostic accuracy (83.9% positivity). In follow-up, a significantly lower DOA was observed in ICP patients (75.1% vs. 86.7%, P = 0.038). The conservative LASSO model identified no robust predictors of DOA, but an exploratory analysis nominated imaging type, immune status, and treatment duration as candidate factors. The clinical presentation of PC is non-specific and cannot reliably differentiate immune status, underscoring the necessity of integrated laboratory and radiographic evaluation. ICP patients present with distinct laboratory abnormalities and more complex imaging patterns. Treatment response assessment should combine clinical, radiographic, and serological trends, as antigen persistence is common. From a clinical perspective, population-based screening is not recommended given the high proportion of incidentally discovered cases; instead, diagnostic vigilance during routine imaging should be emphasized. In immunocompetent patients with small solitary lesions, surgery alone represents an effective option that can reduce the need for prolonged antifungal therapy. Larger prospective studies are needed to validate the exploratory prognostic factors identified.
2026-02-28 | Strain-specific variation in virulence and host-immune modulation across the Cryptococcus gattii species complex.
Cryptococcus gattii is an environmental yeast capable of causing severe infections in immunocompetent hosts. Its virulence mechanisms remain less characterized than those of C. neoformans. This study aimed to evaluate the expression of major virulence factors and the immunomodulatory potential of eight C. gattii strains representing five genotypes and multiple sequence types (STs). Virulence traits-including capsule thickness, melanin and laccase production, phospholipase, hemolysin, urease, and DNase activities-were assessed using standardized in vitro assays. In vivo pathogenicity was evaluated in Galleria mellonella, and macrophage responses were analyzed via nitric oxide (NO) production and cytokine gene expression in J774.A1 cells. Capsule and melanin production varied significantly across strains, with VGI/ST106 and VGII/ST7 showing the highest levels, respectively. VGIV/ST336, VGI/ST106, and VGVI/ST556 induced greater larval mortality than the reference C. neoformans strain (VNI/ST5), while VGII strains exhibited ST-dependent virulence. Most strains inhibited NO production in macrophages, except VGI/ST106, which enhanced it. Cytokine expression remained low in the absence of inflammatory priming. These findings reveal substantial phenotypic variability in virulence and immune modulation among C. gattii strains. Further investigation into strain-specific host interactions may helpthe development of targeted antifungal strategies and improve clinical management of cryptococcosis.
2026-02-25 | An integrative ultrastructural and transcriptomic analysis of host-pathogen interactions with human brain microvascular endothelial cells during cryptococcal infection: a preliminary study.
In humans, Cryptococcus neoformans and Cryptococcus gattii species complexes are the leading cause of fungal meningitis globally. To establish CNS infection, Cryptococcus must breach the BBB, primarily comprised of specialized brain microvascular endothelial cells (BMECs), which is the prerequisite for cryptococci to invade the brain. Despite its clinical impact, the mechanisms underlying host-pathogen interaction at the BBB particularly involving environmental isolates remain under-characterized. This study aimed to investigate the cyto-morphological and transcriptomic responses of HBMECs to infection by clinical and environmental Cryptococcus isolates using a dual approach-ultrastructural electron microscopy and high-throughput dual RNA-Seq. HBMECs were infected in vitro with molecularly typed clinical and environmental isolates of C. neoformans and C. gattii at two infection time points (4 hpi and 18 hpi). Transmission electron microscopy was used to visualize host cell ultrastructural alterations, while dual RNA-Seq was performed to assess differential gene expression in both host and pathogen. TEM revealed extensive ultrastructural changes in infected HBMECs, including membrane ruffling, increased microvilli, mitochondrial alterations, ER dilation, Golgi fragmentation, nuclear deformation, and autophagosome formation. Transcriptomic profiling demonstrated functional enrichment of several critical cryptococcal virulence-associated genes linked to immune evasion and stress adaptation including various immune signaling pathways elicited by the HBMECs as a counter measure to the cryptococcal invasion. Clinical and environmental Cryptococcus isolates exhibit comparable invasive potential and elicit similar host endothelial responses with consistent effects observed across all isolates and time points. This integrative study combining ultrastructural and transcriptomic analyses highlights conserved host-pathogen interactions at the BBB, identifies potential molecular targets for antifungal therapy and underscores the pathogenic relevance of environmental reservoirs in cryptococcal meningitis. cryptococcal meningitis, blood-brain barrier, invasion, transmission electron microscopy, Dual RNASeq, differential gene expression, host-pathogen interaction, HBMECs, ultrastructural alterations.
2025-12-17 | The catalase gene CAT2 and its role in the virulence of one sub-cluster of Cryptococcus gattii VGI clinical isolates.
Cryptococcus gattii causes cryptococcosis and life-threatening cryptococcal meningitis. Currently, the pathogenic virulence mechanisms of C. gattii remain a significant area of ongoing research with considerable unexplored aspects. On the basis of our established research, a sub-cluster of strains with independent evolutionary relationships from WM276 in the phylogenetic analysis of VGI-type strains is identified. In vivo infection experiments on this sub-branch of strains reveal that there are hypervirulent strains and hypovirulent strains among these strains, and the virulence differences are significant ( P < 0.001). Bioinformatic interrogation of differentially expressed genes reveals that the catalase-encoding gene CGB_J0620W, CAT2, is a pivotal virulence-associated gene. The hypervirulent clinical isolate G4 (G4-WT) is selected as the parental strain, from which an isogenic CAT2-knockout mutant ( cat2Δ) is constructed via homologous recombination, which shows increased sensitivity to oxidative stress, as well as growth defects in response to hyperosmosis, 5-fluorocytosine, fluconazole and amphotericin B. The cat2Δ::CAT2 strain exhibits phenotypic restoration to wild type (WT). In the mouse experiments, significant differences in survival ( P < 0.001), pulmonary fungal burden ( P < 0.01), and alveolar structural damage are observed between the WT and cat2Δ strains, which are completely different from C. neoformans. Moreover, comparative transcriptome analysis is performed on the WT and cat2Δ strains, which reveals that enzymes encoded by CAT2 may be involved in oxidative stress, metabolism and sugar transport. In conclusion, this study may explain the differences in virulence among different genetic evolutionary processes of a sub-cluster of the VGI geneotype of C. gattii and provide a theoretical basis for targeted therapy in a specific genotype population in the future.
2025-07-21 | Identification of ATM1 gene involved in antifungal resistance based on CRISPR/Cas9 technology in Cryptococcus gattii.
Cryptococcus gattii is a fungal pathogen that poses significant threats to human health, affecting both immunocompromised and immunocompetent individuals. Treatment of C. gattii infections typically involves the use of antifungal agents, such as azoles. However, the increasing emergence of antifungal resistance in C. gattii is a growing concern, highlighting the critical need for novel therapeutic strategies. In our previous study, we identified a mitochondrial ATP-binding cassette (ABC) transporter, Atm1, as potentially involved in antifungal resistance in C. gattii through transcriptome sequencing, but its function remains unclear and requires additional confirmation and investigation. In this study, we developed a "suicide" clustered regularlyinterspaced short palindromic repeats-CRISPR-associated protein 9 system in C. gattii, based on the system used in C. neoformans, and successfully validated its functionality by targeting the ADE2 gene. We subsequently generated C. gattii mutants lacking ATM1 and assessed their growth under various stress conditions. Our data suggest that Atm1 is involved in the iron-sulfur cluster biosynthesis process. Besides, disruption of ATM1 resulted in various growth impairments, including reduced stress tolerance, impaired capsule formation, and diminished virulence. Importantly, we observed compromised antifungal drug resistance in the atm1∆ mutant and performed RNA sequencing-based transcriptome analysis and gene ontology analysis with and without antifungal treatment for further investigation. In conclusion, our findings indicate that ATM1 plays a role in iron homeostasis and is critical for antifungal resistance in C. gattii, offering new insights into potential drug development strategies for the clinical treatment of cryptococcosis.
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Drug Discovery Landscape
7 orphan drug designations for Cryptococcosis, including 1 approved therapy.
7 orphan drug designations for Cryptococcosis, including 1 approved therapy.
Drug | Therapy type | Orphan designation | Clinical trial status | Sponsor |
|---|---|---|---|---|
Flucytosine Injection for intravenous Infusion | small molecules | FDA | Cipla Ltd. | |
Amphotericin B | small molecules | EMA | Insight Drug Regulatory | |
Encochleated oral Amphotericin B suspension | small molecules | FDA | Matinas BioPharma Nanobiotechnologies, Inc. | |
fosmanogepix | small molecules | FDA | — | Basilea Pharmaceutica Ltd, Allschwil |
1-(4-(N-glycylamido)phenyl)-3-trifluoromethyl-5-(phenanthren-2-yl)-pyrazole-hydrochloride | small molecules | EMA | — | Arno Therapeutics UK, Limited |
selective inhibitor of fungal lanosterol demethylase | small molecules | FDA | — | Viamet Pharmaceuticals, Inc. |
Liposomal amphotericin B [AmBisome] | small molecules | FDA | Approved | Fujisawa USA, Inc. |
“Terminated” – programs with discontinued clinical trials, or with no updates reported for 5 years after completion or 12 years after the last trial started.
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