RARE DISEASE
Paracoccidioidomycosis
Paracoccidioidomycosis
Paracoccidioidomycosis
Drug discovery
0
drugs
With orphan designations
Overview
Paracoccidioidomycosis (PCM) is a systemic fungal infection caused by Paracoccidioides species, endemic to rural regions of Central and South America. Transmission occurs via inhalation of soil-dwelling fungal spores, primarily affecting immunocompetent adults with occupational exposure to soil. Clinical manifestations range from asymptomatic infection to chronic pulmonary, mucocutaneous, or disseminated disease. Diagnosis relies on microscopy, histopathology, culture, or serology. First-line treatment includes long-term azoles (e.g., itraconazole) or sulfamethoxazole-trimethoprim, with amphotericin B reserved for severe cases [1][6][11].
Population
Predominantly affects men aged 20–50 years (male-to-female ratio up to 15:1), particularly agricultural workers in Brazil, Colombia, Venezuela, and Argentina [1][7][12].
Higher susceptibility reported in white populations compared to non-white individuals in endemic areas [12][13].
Immunocompromised patients (e.g., HIV/AIDS) present with aggressive, disseminated forms [4][6].
Therapies
Categories: rare infectious diseases
Research Papers
722 drug discovery papers about Paracoccidioidomycosis, with 1 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
722 drug discovery papers about Paracoccidioidomycosis, with 1 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
small molecules
2026-08-14 | Pre-Exposure to Cyclosporine A Primes Paracoccidioides brasiliensis to Evade Host Immunity.
Paracoccidioidomycosis (PCM) is a systemic mycosis endemic to South America caused by thermodimorphic fungi of the genus Paracoccidioides, particularly P. brasiliensis. Calcineurin inhibition by cyclosporine A (CsA) perturbs fungal thermodimorphism and growth. Here, we asked whether pre-exposure of P. brasiliensis yeasts to CsA modulates host-pathogen interactions during infection. Mice infected with CsA-pre-exposed fungi exhibited significantly reduced levels of pro- and anti-inflammatory cytokines, along with decreased recruitment and activation of innate and adaptive immune cells at both time points. Although tissue inflammation and lesion areas were diminished, fungal burdens in lungs and liver were similar between groups. Importantly, yeasts recovered from lungs 72 h after infection with CsA-pretreated fungi displayed reduced in vitro colony growth, suggesting that prior CsA exposure induces a persistent slow-growth physiological state. This altered phenotype may impair effective immune recognition and inflammatory activation. As host immunosuppression was excluded in the experimental design, fungus-intrinsic phenotypes consistent with transient calcineurin pathway inhibition: altered growth/morphogenesis and putatively modified PAMP exposure that together blunt early immune activation. We interpret late-phase differences as downstream of these early pathway-dependent shifts rather than as heritable reprogramming. Overall, pre-exposure to CsA modulates P. brasiliensis-host interaction, dissociating tissue injury from fungal burden, highlights the role of calcineurin in fungal adaptation, and demonstrates how environmental exposure to bioactive compounds can influence fungal virulence and disease outcomes.
2026-08-07 | Novel antifungal agents for treating endemic mycoses: hope on the horizon?
Current treatments for endemic mycoses are limited by toxicity, drug-drug interactions, the need for therapeutic drug monitoring, and suboptimal penetration to sequestered sites. At the same time, several new antifungal strategies and agents are nearing clinical availability and may change practice. Current literature highlights limitations of standard therapy for histoplasmosis, coccidioidomycosis, blastomycosis, paracoccidioidomycosis, talaromycosis, sporotrichosis, and emergomycosis, which often rely on amphotericin B-based induction regimens followed by triazole antifungals. Emerging studies are evaluating single high-dose liposomal amphotericin B, shorter treatment durations for histoplasmosis, and flucytosine combined with amphotericin B-based induction for talaromycosis. Novel antifungals such as olorofim, fosmanogepix, and turletricin are especially promising, and treatment strategies guided by patient phenotypes and immune endotypes are also beginning to emerge. Growing evidence suggests therapy for endemic mycoses may change substantially in the near future. New drugs and alternative treatment approaches have the potential to improve safety, tolerability, oral availability, drug-drug interaction profiles, and treatment duration, with important implications for both clinical care and future research.
2026-06-08 | Disseminated paracoccidioidomycosis with a pulmonary-spine fistula: suggestive of contiguous spread.
Paracoccidioidomycosis (PCM) rarely involves the spine. We report a 55-year-old man with disseminated PCM presenting with thoracic spinal cord compression and an unprecedented pulmonary-spine fistula identified intraoperatively. Diagnosis was confirmed by histopathology and mycology. The patient underwent surgical decompression and stabilization followed by itraconazole, achieving complete neurological recovery. This case highlights a unique complication of PCM and supports combined surgical and antifungal management in cases with neurological compromise.
2026-03-11 | LC3-associated phagocytosis in macrophage responses to Paracoccidioides spp.
Paracoccidioidomycosis (PCM) is a systemic infection that is endemic to Latin America, caused by thermodimorphic fungi from the Paracoccidioides genus. These fungi are facultative intracellular parasites of macrophages. LC3-associated phagocytosis (LAP), a non-canonical form of autophagy, plays a critical role in the response of these phagocytes to similar pathogens. In this study, we investigated the role of LAP in the macrophage responses to Paracoccidioides spp. We detected LAP in macrophages infected with Paracoccidioides spp by immunofluorescence microscopy with antibodies to LC3. Piceatannol and diphenyleneiodonium chloride (DPI), respectively Syk and nicotinamide adenine dinucleotide phosphate oxidase (NADPH) inhibitors, were used to understand the role their pathways played. To determine the function of LAP, we targeted ATG5, a key autophagy gene, by RNA interference. We observed LC3 recruitment to phagosomes containing Paracoccidioides spp. in RAW264.7 and J774.16 cell lines and in bone marrow-derived macrophages. ATG5 RNA interference reduced the antifungal activity of J774.16 cells, highlighting the importance of LC3 recruitment for effective fungal control. Interestingly, pharmacological inhibition of Syk kinase and NADPH oxidase pathways, essential for LAP against Aspergillus fumigatus and Candida albicans, did not impair LAP against P. brasiliensis. This suggests distinct triggering mechanisms, possibly due to differences in the fungal cell surface composition. These findings suggest that LAP plays a significant role in the host defense against Paracoccidioides spp. and may represent a promising target for host-directed PCM therapies.
2026-03-01 | EPIDEMIOLOGICAL PROFILE OF DEATHS AMONG BRAZILIANS DUE TO PARACOCCIDIOIDOMYCOSIS BETWEEN 2013 AND 2023
Paracoccidioidomycosis is an endemic systemic mycosis and is among the ten leading causes of death from chronic and infectious diseases in Brazil. Its incidence ranges from 0.71 to 3.10 cases per 100,000 inhabitants per year in Brazil. In this context, this study aimed to analyze the epidemiological profile of deaths among Brazilians due to this disease between 2013 and 2023. Ecological study analyzing secondary data obtained from the Brazilian public health informatics platform (DATASUS), using the Mortality Information System (SIM). Data were included for paracoccidioidomycosis across Brazilian regions, considering the variables: sex, age group, ethnicity, and year of death from 2013 to 2023. Between 2013 and 2023, 774 deaths due to paracoccidioidomycosis were recorded in Brazil, distributed as follows: 105 in the North (13.5%), 367 in the Southeast (47.4%), 171 in the South (22.0%), 95 in the Central-West (12.2%), and 36 in the Northeast (4.6%). This indicates endemicity in the Southeast, which concentrated 47.4% (n = 367) of records. Regarding age group, there was predominance among individuals aged 50–59 years, with 226 deaths (29.2% of the total). Males were the most affected, accounting for 85.6% (n = 663) of confirmed cases. Regarding ethnicity, whites predominated with 51.0% (n = 395), followed by mixed race (“pardo”) with 35.1% (n = 272), Black with 10.3% (n = 80), Indigenous with 0.77% (n = 6), Asian with 0.38% (n = 3), and unknown with 2.3% (n = 18). In addition, the largest percentage increases in deaths were observed in almost all regions between 2018 and 2019 (15%) and between 2020 and 2021 (28%). These data reinforce that paracoccidioidomycosis is an important cause of mortality in Brazil, with endemicity in the Southeast and predominance among males, whites, and individuals aged 50–59 years. These findings indicate that prevention measures focused mainly on men and active screening in risk groups—considering both acute outbreaks and environmental exposure history—are essential. Understanding risk factors, exposure patterns, and immune response may help reduce disease burden, especially alongside improved reporting observed between 2020 and 2021.
vaccines
2024-10-06 | Nanoformulated CHO-rPb27 vaccine enhances immunity and controls infection, mitigating lung inflammation and dysfunction during experimental Paracoccidioidomycosis in mice.
Paracoccidioidomycosis (PCM) is a systemic mycosis caused by the dimorphic fungus within the genus Paracoccidioides, particularly Paracoccidioides brasiliensis. The traditional approach to treating this pulmonary infection involves prolonged therapy periods, ranging from weeks to years, often resulting in a notable frequency of disease relapse. Nanotechnology has emerged as a promising avenue for developing novel antifungal therapies and effective vaccines. This is attributed to its capability to facilitate targeted drug and antigen delivery, thereby mitigating toxicity and treatment expenses. This study investigates the synergistic properties of the CHO-rPb27 vaccine nanoformulation against experimental PCM. The therapeutic efficacy of CHO-rPb27 treatment is juxtaposed with the prophylactic protocol. Our findings demonstrate that both protocols effectively control P. brasiliensis pulmonary infection by eliciting a robust cellular and humoral immune response. This response attenuates chronic tissue damage and mitigates pulmonary mechanical dysfunction in mice.
2023-11-27 | Dectin-2 is critical for phagocyte function and resistance to Paracoccidioides brasiliensis in mice.
Germline-encoded pattern recognition receptors, particularly C-type lectin receptors (CLRs), are essential for phagocytes to sense invading fungal cells. Among CLRs, Dectin-2 (encoded by Clec4n) plays a critical role in the antifungal immune response as it recognizes high-mannose polysaccharides on the fungal cell wall, triggering phagocyte functional activities and ultimately determining adaptive responses. Here, we assessed the role of Dectin-2 on the course of primary Paracoccidioides brasiliensis systemic infection in mice with Dectin-2-targeted deletion. Paracoccidioides brasiliensis constitutes the principal etiologic agent of paracoccidioidomycosis, the most prominent invasive mycosis in Latin American countries. The deficiency of Dectin-2 resulted in shortened survival rates, high lung fungal burden, and increased lung pathology in mice infected with P. brasiliensis. Consistently, dendritic cells (DCs) from mice lacking Dectin-2 infected ex vivo with P. brasiliensis showed impaired secretion of several proinflammatory and regulatory cytokines, including TNF-α, IL-1β, IL-6, and IL-10. Additionally, when cocultured with splenic lymphocytes, DCs were less efficient in promoting a type 1 cytokine pattern secretion (i.e., IFN-γ). In macrophages, Dectin-2-mediated signaling was required to ensure phagocytosis and fungicidal activity associated with nitric oxide production. Overall, Dectin-2-mediated signaling is critical to promote host protection against P. brasiliensis infection, and its exploitation might lead to the development of new vaccines and immunotherapeutic approaches. We report a critical role of the innate immune receptor Dectin-2 during Paracoccidioides brasiliensis infection. Fungal sensing by Dectin-2 improved the survival of mice and lowered fungal burden. Further, Dectin-2 was required for cytokine production, phagocytosis, and fungal killing by phagocytes.
2021-11-01 | Identification of Potentially Therapeutic Immunogenic Peptides From Paracoccidioides lutzii Species.
Paracoccidioidomycosis (PCM) is an endemic mycosis in Latin America caused by the thermodimorphic fungi of the genus Paracoccidioides spp. Paracoccidioides lutzii (PL) is one of the 5 species that constitute the Paracoccidioides genus. PL expresses low amounts of glycoprotein (Gp) 43 (PLGp43) and PLGp43 displays few epitopes in common with the P. brasiliensis (PB) immunodominant antigen PBGp43, which is commonly used for serological diagnosis of PCM. This difference in structure between the glycoproteins markedly reduces the efficiency of serological diagnosis in patients infected with PL. We previously demonstrated that peptide 10 (P10) from the PBGp43 induces protective immune responses in in vitro and in vivo models of PB PCM. Since, P10 has proven to be a promising therapeutic to combat PB, we sought to identify peptides in PL that could similarly be applied for the treatment of PCM. PL yeast cell proteins were isolated from PL: dendritic cell co-cultures and subjected to immunoproteomics. This approach identified 18 PL peptides that demonstrated in silico predictions for immunogenicity. Eight of the most promising peptides were synthesized and applied to lymphocytes obtained from peptide-immunized or PL-infected mice as well as to in vitro cultures with peptides or dendritic cells pulsed the peptides. The peptides LBR5, LBR6 and LBR8 efficiently promoted CD4+ and CD8+ T cell proliferation and dendritic cells pulsed with LBR1, LBR3, LBR7 or LBR8 stimulated CD4+ T cell proliferation. We observed increases of IFN-γ in the supernatants from primed T cells for the conditions with peptides without or with dendritic cells, although IL-2 levels only increased in response to LBR8. These novel immunogenic peptides derived from PL will be employed to develop new peptide vaccine approaches and the proteins from which they are derived can be used to develop new diagnostic assays for PL and possibly other Paracoccidioides spp. These findings identify and characterize new peptides with a promising therapeutic profile for future against this important neglected systemic mycosis.
2020-09-18 | Medication association and immunomodulation: An approach in fungal diseases and in particular in the treatment of paracoccidioidomycosis.
Fungal infections have been increasing in recent decades, mainly affecting immunocompromised individuals, although certain mycoses, such as paracoccidioidomycosis (PCM), infect immunologically competent individuals. The major problems observed regarding fungal diseases are inadequate diagnosis, prolonged treatment time, the reduced number of drugs available for treatment, in addition to the fact that there are no vaccines for clinical use. Drug combination in order to immunomodulate the immune response is a new strategy used for the treatment of mycoses, since it is difficult to develop new antifungal drugs. The aim of this study is to present and analyze strategies recently suggested for the treatment of fungi of medical interest, in particular for PCM, such as the utilization of combinations of protein fractions or dead microorganisms, as vaccinal antigens, and cellular immunotherapy. We will also propose new therapeutic alternatives, such as lipids, vitamins, synthetic or natural products as well as the use of low intensity LASER therapy (LLLT) to modulate the immune response of the host, enhancing the efficiency of the existing treatments of mycoses of medical interest and in particular of PCM.
2019-11-26 | 43 kDa Glycoprotein (gp43) from Paracoccidioides brasiliensis Induced IL-17A and PGE2 Production by Human Polymorphonuclear Neutrophils: Involvement of TLR2 and TLR4.
The glycoprotein gp43 is the major antigenic/diagnostic component of Paracoccidioides brasiliensis , one of the etiologic agents of paracoccidioidomycosis (PCM). Gp43 has protective roles in mice, but due to adhesive properties, this glycoprotein has also been associated with immune evasion mechanisms. The present study evaluated gp43 interaction in vitro with Toll-like receptors 2 and 4 (TLR2 and TLR4) present in polymorphonuclear neutrophils (PMNs) from healthy human individuals and the consequent modulation of the immune response through the expression and release of cytokines and eicosanoids. PMNs were incubated in the absence or presence of monoclonal antibodies anti-TLR2 and anti-TLR4 (individually or in combination) before gp43 stimulation. Then, PMNs were analyzed for the expression of both surface receptors and the detection of intracytoplasmic IL-17A and IL-4 using flow cytometry, while the production of PGE2, LTB4, IL-6, IL-10, IL-12, IFN- γ , and TNF- α was evaluated in the supernatants by enzyme-linked immunosorbent assay (ELISA). Our results showed that gp43 increased TLR2 and TLR4 expression by PMNs and induced PGE2 and IL-17A via TLR4 and TLR2, respectively. Thus, our data suggest that gp43 from P. brasiliensis might modulate host susceptibility to the fungal infection by affecting PGE2 and IL-17A production.
antibodies
2026-01-23 | Single-cell RNA sequencing of CTLA-4 and PD-1 blockade in pulmonary paracoccidioidomycosis highlights a protective transcriptional program mediated by activated Th17 cells, neutrophils and macrophages
ABSTRACT Pulmonary paracoccidioidomycosis (PCM) relies on a finely balanced lung-immune network in which Th17, Treg, neutrophils, and macrophages orchestrate fungal control and tissue integrity. Furthermore, within the context of single-cell sequencing, little is known about how immune checkpoint inhibition modulates this balance during systemic mycosis. In a previous study we verified that the blockade of checkpoint molecules (CTLA-4 and PD-1) restores protective immunity that reduces fungal loads, tissue pathology and mortality of infected mice. Here, we have further studied this model by single-cell RNA sequencing on lung leukocytes from mice infected with Paracoccidioides brasiliensis and treated with anti-CTLA-4 or anti-PD-1 antibodies to define the cellular and molecular consequences of checkpoint blockade in vivo. We generated a high-resolution atlas covering T cells, neutrophils, macrophages/monocytes, B cells, NK cells, and epithelial subsets. Checkpoint inhibition consistently remodeled the CD4⁺ T cell compartment toward a Th17-enriched program, with reduced interleukin-10 expressing Treg frequencies and a prominent interleukin-17A⁺ (IL-17), C-C chemokine receptor type 2⁺, CXC chemokine (CXC) receptor type 6⁺, CD44⁺ ( Il17a ⁺ Ccr2 ⁺ Cxcr6 ⁺ Cd44 ⁺) signature. This shift was accompanied by the expansion and activation of neutrophils and macrophages expressing tumor necrosis factor and chemokines (including CXC motif chemokine ligand ( Cxcl 1, Cxcl2 and Ccl4 ), microbicidal-associated genes (S100 calcium-binding protein A8 and A9), and regulatory mediators such as secretory leukocyte protease inhibitor and interleukin-15. Ligand–receptor and trajectory analyses revealed a reinforced Th17–myeloid communication axis, particularly under CTLA-4 blockade, converging on IL17–centered inflammatory circuits while attenuating canonical Treg checkpoints (cytotoxic T-lymphocyte-associated protein 4, programmed cell death protein 1, interleukin-10). Together, these data demonstrate that anti-CTLA-4 and anti-PD-1 immunotherapies profoundly rewire the lung-immune microenvironment during PCM, amplifying effector Th17–neutrophil–macrophage networks that benefits protective antifungal activity Our work provides a mechanistic framework for evaluating immune checkpoint inhibitors in chronic fungal infections.
2025-11-03 | The Role of Myeloid-Derived Suppressor Cell (MDSC) in Fungal Infections and Its Potential as a Therapeutic Target.
The interaction between the immune system and fungi has long intrigued researchers, as fungi are among the most common organisms encountered by humans. Myeloid-derived suppressor cells (MDSCs) are specialized immune cells that play a key role in modulating immune responses during fungal infections by inhibiting T-cell activity. This review aims to investigate the mechanisms by which MDSCs influence fungal infections and to explore their potential as therapeutic targets. A comprehensive review of existing studies examining MDSC activity in various fungal infections was conducted. Comparative analysis focused on the protective versus non-protective effects of MDSCs across different fungal species. MDSCs suppress pro-inflammatory T-cell responses, leading to two contrasting outcomes. On one hand, this suppression mitigates disease progression by reducing harmful inflammation. On the other, it can enhance fungal survival by preventing T-cell-mediated damage. Protective effects of MDSCs have been observed in Candida albicans infections, whereas non-protective or detrimental effects have been reported in infections caused by Candida tropicalis, Paracoccidioides, Aspergillus fumigatus, Cryptococcus neoformans, Malassezia, and Mucor species. MDSCs play a dual role in fungal infections, balancing protective immune regulation with facilitation of fungal persistence. Understanding their mechanisms offers promising avenues for the development of targeted immunotherapies against fungal pathogens.
2024-09-20 | Paracoccidioides spp.: Escape mechanisms and their implications for the development of this mycosis.
Paracoccidioidomycosis (PCM) is a systemic granulomatous mycosis prevalent in individuals who carry out rural activities. Its etiological agent is a thermodimorphic fungus belonging to the genus; Paracoccidioides spp. Seven species of this fungus are known: Paracoccidioides brasiliensis, Paracoccidioides lutzii, Paracoccidioides americana, Paracoccidioides restrepiensis, Paracoccidioides venezuelensis, Paracoccidioides loboi and Paracoccidioides ceti. For a long time, Paracoccidioides brasiliensis was attributed as the only causal agent of this mycosis. What is known about adhesins, virulence, escape mechanisms and fungal involvement with the host's immune system is correlated with the species Paracoccidioides brasiliensis. Interactions between Paracoccidioides spp. and the host are complex and dynamic. The fungus needs nutrients for its needs and must adapt to a hostile environment, evading the host's immune system, thus enabling the development of the infectious process. On the other hand, the host's immune system recognizes Paracoccidioides spp. and employs all protective mechanisms to prevent fungal growth and consequently tissue invasion. Knowing this, understanding how Paracoccidioides spp. escapes the host's immune system, can help to understand the pathogenic mechanisms related to the development of the disease and, therefore, in the design of new specific treatment strategies. In this review we discuss these mechanisms and what are the adhesion molecules of Paracoccidioides spp. uses to escape the hostile environment imposed by the host's defense mechanisms; finally, we suggest how to neutralize them with new antifungal therapies.
2024-07-22 | MDSCs use a complex molecular network to suppress T-cell immunity in a pulmonary model of fungal infection.
Paracoccidioidomycosis (PCM) is a systemic endemic fungal disease prevalent in Latin America. Previous studies revealed that host immunity against PCM is tightly regulated by several suppressive mechanisms mediated by tolerogenic plasmacytoid dendritic cells, the enzyme 2,3 indoleamine dioxygenase (IDO-1), regulatory T-cells (Tregs), and through the recruitment and activation of myeloid-derived suppressor cells (MDSCs). We have recently shown that Dectin-1, TLR2, and TLR4 signaling influence the IDO-1-mediated suppression caused by MDSCs. However, the contribution of these receptors in the production of important immunosuppressive molecules used by MDSCs has not yet been explored in pulmonary PCM. We evaluated the expression of PD-L1, IL-10, as well as nitrotyrosine by MDSCs after anti-Dectin-1, anti-TLR2, and anti-TLR4 antibody treatment followed by P. brasiliensis yeasts challenge in vitro. We also investigated the influence of PD-L1, IL-10, and nitrotyrosine in the suppressive activity of lung-infiltrating MDSCs of C57BL/6-WT, Dectin-1KO, TLR2KO, and TLR4KO mice after in vivo fungal infection. The suppressive activity of MDSCs was evaluated in cocultures of isolated MDSCs with activated T-cells. A reduced expression of IL-10 and nitrotyrosine was observed after in vitro anti-Dectin-1 treatment of MDSCs challenged with fungal cells. This finding was further confirmed in vitro and in vivo by using Dectin-1KO mice. Furthermore, MDSCs derived from Dectin-1KO mice showed a significantly reduced immunosuppressive activity on the proliferation of CD4+ and CD8+ T lymphocytes. Blocking of TLR2 and TLR4 by mAbs and using MDSCs from TLR2KO and TLR4KO mice also reduced the production of suppressive molecules induced by fungal challenge. In vitro, MDSCs from TLR4KO mice presented a reduced suppressive capacity over the proliferation of CD4+ T-cells. We showed that the pathogen recognition receptors (PRRs) Dectin-1, TLR2, and TLR4 contribute to the suppressive activity of MDSCs by inducing the expression of several immunosuppressive molecules such as PD-L1, IL-10, and nitrotyrosine. This is the first demonstration of a complex network of PRRs signaling in the induction of several suppressive molecules by MDSCs and its contribution to the immunosuppressive mechanisms that control immunity and severity of pulmonary PCM.
2024-03-04 | Blocking the CTLA-4 and PD-1 pathways during pulmonary paracoccidioidomycosis improves immunity, reduces disease severity, and increases the survival of infected mice
Immune checkpoint pathways, i.e., coinhibitory pathways expressed as feedback following immune activation, are crucial for controlling an excessive immune response. Cytotoxic T lymphocyte antigen-4 (CTLA-4) and programmed cell death protein-1 (PD-1) are the central classical checkpoint inhibitory (CPI) molecules used for the control of neoplasms and some infectious diseases, including some fungal infections. As the immunosuppression of severe paracoccidioidomycosis (PCM), a chronic granulomatous fungal disease, was shown to be associated with the expression of coinhibitory molecules, we hypothesized that the inhibition of CTLA-4 and PD-1 could have a beneficial effect on pulmonary PCM. To this end, C57BL/6 mice were infected with Paracoccidioides brasiliensis yeasts and treated with monoclonal antibodies (mAbs) α-CTLA-4, α-PD-1, control IgG, or PBS. We verified that blockade of CTLA-4 and PD-1 reduced the fungal load in the lungs and fungal dissemination to the liver and spleen and decreased the size of pulmonary lesions, resulting in increased survival of mice. Compared with PBS-treated infected mice, significantly increased levels of many pro- and anti-inflammatory cytokines were observed in the lungs of α-CTLA-4-treated mice, but a drastic reduction in the liver was observed following PD-1 blockade. In the lungs of α-CPI and IgG-treated mice, there were no changes in the frequency of inflammatory leukocytes, but a significant reduction in the total number of these cells was observed. Compared with PBS-treated controls, α-CPI- and IgG-treated mice exhibited reduced pulmonary infiltration of several myeloid cell subpopulations and decreased expression of costimulatory molecules. In addition, a decreased number of CD4+ and CD8+ T cells but sustained numbers of Th1, Th2, and Th17 T cells were detected. An expressive reduction in several Treg subpopulations and their maturation and suppressive molecules, in addition to reduced numbers of Treg, TCD4+, and TCD8+ cells expressing costimulatory and coinhibitory molecules of immunity, were also detected. The novel cellular and humoral profiles established in the lungs of α-CTLA-4 and α-PD-1-treated mice but not in control IgG-treated mice were more efficient at controlling fungal growth and dissemination without causing increased tissue pathology due to excessive inflammation. This is the first study demonstrating the efficacy of CPI blockade in the treatment of pulmonary PCM, and further studies combining the use of immunotherapy with antifungal drugs are encouraged.
proteins
2025-01-10 | HIGH MOLECULAR MASS ANTIGENIC COMPONENTS OF PARACOCCIDIOIDES BRASILIENSIS: PARTIAL CHARACTERIZATION AND IMPLICATIONS IN THE TH1 RESPONSE
Paracoccidioidomycosis (PCM) is a chronic infection caused by the fungi Paracoccidioides brasiliensis or P. lutzii, whose host defense is mediated by Th1 lymphocytes. This study aimed to purify and evaluate the effect of high molecular mass (hMM) components of P. brasiliensis on the cellular immune response. The soluble antigens of the fungus (Pb18) were subjected to chromatography on a Sephadex G-200 column followed by HPLC, obtaining the fraction F17 (~380 kDa) and its subfraction F17-IV (~70 kDa), both reactive to sera from patients with PCM. The fractions were tested in vitro with splenic cells from infected mice, resulting in a lymphoproliferative response and increased levels of INF-γ and IL-10, without alteration of IL-4. These findings indicate the activation of the Th1 immune response and suggest that the ~380 kDa fraction can degrade to generate active subcomponents of ~70 kDa. The ~70 kDa subcomponent appears to be distinct from the gp70 described in the literature, given its ability to induce INF-γ. The results indicate the immunogenic potential of these components, highlighting their relevance for the development of vaccines or therapies against PCM.
2024-03-21 | Recombinant 60-kDa heat shock protein from Paracoccidioides brasiliensis induces the death of mouse lymphocytes in a mechanism dependent on Toll-like receptor 4 and tumor necrosis factor
Paracoccidioides fungi are thermodimorphic microorganisms that cause paracoccidioidomycosis (PCM), an autochthonous disease from Latin America, with most cases in Brazil. Humans become infected by inhaling conidia or mycelial fragments that transform into yeast at body temperature. These fungi cause chronic-granulomatous inflammation, which may promote fibrosis and parenchyma destruction in the lungs. In response to stress imposed by the host, fungi Paracoccidioides spp. increase the expression of heat shock proteins (HSP), which protect them by sustaining cellular proteostasis. Our group has studied the role of HSP60 in PCM, and previous data show that the recombinant HSP60 (rHSP60) has a deleterious effect when used in a single dose as therapy for experimental PCM. Here, we investigated the mechanism by which rHSP60 could worsen the disease. We found that rHSP60 caused the viability loss of splenic or lymph node cells from both immunized and non-immunized mice, including in splenic T lymphocytes under polyclonal stimulation with concanavalin A, probably by undergoing apoptosis. Among analyzed splenic cells, lymphocytes were indeed the main cells to die. When we investigated the death mechanisms, remarkably, we found that there was no viability loss in rHSP60-stimulated splenic cells from mice deficient in Toll-like receptor 4, TRIF adapter protein, and TNF receptor 1(TNFR1), as well as rHSP60-stimulated WT cells incubated with anti-TNF antibody. Besides, caspase-8 inhibitor IETD-CHO blocked the rHSP60 effect on splenic cells, suggesting that rHSP60 induces the extrinsic apoptosis pathway dependent on signaling via TLR4/TRIF and TNFR1.
2023-11-16 | Proteomic analysis reveals changes in the proteome of human THP-1 macrophages infected with Paracoccidioides brasiliensis
Paracoccidioides spp. is the etiologic agent of Paracoccidioidomycosis (PCM), a systemic disease with wide distribution in Latin America. Macrophages are very important cells during the response to infection by P. brasiliensis . In this study, we performed a proteomic analysis to evaluate the consequences of P. brasiliensis yeast cells on the human THP-1 macrophage proteome. We have identified 443 and 2247 upregulated or downregulated proteins, respectively, in macrophages co-cultured with yeast cells of P. brasiliensis in comparison to control macrophages unexposed to the fungus. Proteomic analysis revealed that interaction with P. brasiliensis caused metabolic changes in macrophages that drastically affected energy production pathways. In addition, these macrophages presented regulated many factors related to epigenetic modifications and gene transcription as well as a decrease of many proteins associated to the immune system activity. This is the first human macrophage proteome derived from interactions with P. brasiliensis , which contributes to elucidating the changes that occur during the host response to this fungus. Furthermore, it highlights proteins that may be targets for the development of new therapeutic approaches to PCM.
2023-02-12 | Biodistribution and Adjuvant Effect of an Intranasal Vaccine Based on Chitosan Nanoparticles against Paracoccidioidomycosis
Paracoccidioidomycosis (PCM) is a fungal infection caused by the thermodimorphic Paracoccidioides sp. PCM mainly affects the lungs, but, if it is not contained by the immune response, the disease can spread systemically. An immune response derived predominantly from Th1 and Th17 T cell subsets facilitates the elimination of Paracoccidioides cells. In the present work, we evaluated the biodistribution of a prototype vaccine based on the immunodominant and protective P. brasiliensis P10 peptide within chitosan nanoparticles in BALB/c mice infected with P. brasiliensis strain 18 (Pb18). The generated fluorescent (FITC or Cy5.5) or non-fluorescent chitosan nanoparticles ranged in diameter from 230 to 350 nm, and both displayed a Z potential of +20 mV. Most chitosan nanoparticles were found in the upper airway, with smaller amounts localized in the trachea and lungs. The nanoparticles complexed or associated with the P10 peptide were able to reduce the fungal load, and the use of the chitosan nanoparticles reduced the necessary number of doses to achieve fungal reduction. Both vaccines were able to induce a Th1 and Th17 immune response. These data demonstrates that the chitosan P10 nanoparticles are an excellent candidate vaccine for the treatment of PCM.
2023-01-06 | Role of paracoccin on Paracoccidioides brasiliensis virulence and susceptibility to antifungal drugs in the Galleria mellonella larvae model.
Paracoccin (PCN), a Paracoccidioides brasiliensis glycoprotein, has been reported to play roles in fungal biology and paracoccidioidomycosis pathogenesis. Lectin and chitinase domains account for the PCN's dual roles as an immunomodulatory agent and virulence factor. Soluble PCN injected in P. brasiliensis infected mice, by interacting with TLRs' N-glycans, drives the host immune response toward a protective Th1 axis. Otherwise, mice infection with yeasts overexpressing PCN (ov-PCN) revealed that PCN acts as a fungal virulence factor, thanks to its chitinase activity on the cell wall, resulting in resistance to phagocytes' fungicidal activity and development of severe paracoccidioidomycosis. Because antifungal drug administration follows the disease diagnosis, we studied the PCN effect on yeast resistance or susceptibility to antifungal agents. Using a paracoccidioidomycosis model developed in Galleria mellonella larvae, we confirmed the observation, in the murine host, that ov-PCN yeasts display maximum virulence compared to wild-type (wt-PCN) or PCN-silenced (kd-PCN) yeasts. PCN overexpression accounted for the highest susceptibility of P. brasiliensis to antifungal and reduced relative mRNA expression of genes encoding proteins related to cell wall remodeling. The lowest virulence, detected in infection with kd-PCN yeasts, correlated with the lowest susceptibility to antifungals and impact on genes for cell wall remodeling. So, we defined that the grade of endogenous PCN production influences the P. brasiliensis virulence and susceptibility to antifungal drugs, as well as the expression of genes related to cell wall remodeling. We postulate that this variable gene expression is mechanistically associated with P. brasiliensis virulence changes.
other
2024-02-23 | Unveiling the functional significance of the 14.3.3 protein: A key player in Paracoccidioides brasiliensis biofilm formation.
Paracoccidioidomycosis (PCM) is a systemic mycosis caused by Paracoccidioides spp. The interaction mediated by the presence of adhesins on the fungal surface and receptors in the extracellular matrix of the host, as well as the biofilm formation, is essential in its pathogenesis. Adhesins such as gp43, enolase, GAPDH (glyceraldehyde-3-phosphate dehydrogenase), and 14-3-3 have been demonstrated in the Paracoccidioides brasiliensis (Pb18) strain and recognized as necessary in the fungus-host interaction. The Pb 18 strain silenced to 14-3-3 showed changes in morphology, virulence, and adhesion capacity. The study aimed to evaluate the role of adhesin 14-3-3 in P. brasiliensis biofilm formation and the differential expression of genes related to adhesins, comparing planktonic and biofilm forms. The presence of biofilm was also verified in sutures in vitro and in vivo. The silenced strain (Pb14-3-3 aRNA) was compared with the wild type Pb18, determining the differential metabolic activity between the strains by the XTT reduction assay; the biomass by violet crystal and the polysaccharides by safranin, even as morphological differences by microscopic techniques. Differential gene expression for adhesins was also analyzed, comparing the relative expression of these in planktonic and biofilm forms at different times. The results suggested that the silencing of 14-3-3 protein altered the ability to form biofilm and its metabolism. The quantity of biomass was similar in both strains; however, the formation of exopolymeric substances and polysaccharide material was lower in the silenced strain. Our results showed increased expression of enolase, GAPDH, and 14-3-3 genes in the first periods of biofilm formation in the Pb18 strain. In contrast, the silenced strain showed a lower expression of these genes, indicating that gene silencing can influence the expression of other genes and be involved in the biofilm formation of P. brasiliensis. In vitro and in vivo assays using sutures confirmed this yeast's ability to form biofilm and may be implicated in the pathogenesis of paracoccidioidomycosis.
2023-10-06 | Immunomodulatory Potential of Fungal Extracellular Vesicles: Insights for Therapeutic Applications
Extracellular vesicles (EVs) are membranous vesicular organelles that perform a variety of biological functions including cell communication across different biological kingdoms. EVs of mammals and, to a lesser extent, bacteria have been deeply studied over the years, whereas investigations of fungal EVs are still in their infancy. Fungi, encompassing both yeast and filamentous forms, are increasingly recognized for their production of extracellular vesicles (EVs) containing a wealth of proteins, lipids, and nucleic acids. These EVs play pivotal roles in orchestrating fungal communities, bolstering pathogenicity, and mediating interactions with the environment. Fungal EVs have emerged as promising candidates for innovative applications, not only in the management of mycoses but also as carriers for therapeutic molecules. Yet, numerous questions persist regarding fungal EVs, including their mechanisms of generation, release, cargo regulation, and discharge. This comprehensive review delves into the present state of knowledge regarding fungal EVs and provides fresh insights into the most recent hypotheses on the mechanisms driving their immunomodulatory properties. Furthermore, we explore the considerable potential of fungal EVs in the realms of medicine and biotechnology. In the foreseeable future, engineered fungal cells may serve as vehicles for tailoring cargo- and antigen-specific EVs, positioning them as invaluable biotechnological tools for diverse medical applications, such as vaccines and drug delivery.
2021-10-06 | Mesenchymal Stromal Cells: an Antimicrobial and Host-Directed Therapy for Complex Infectious Diseases
There is an urgent need for new antimicrobial strategies for treating complex infections and emerging pathogens. Human mesenchymal stromal cells (MSCs) are adult multipotent cells with antimicrobial properties, mediated through direct bactericidal activity and modulation of host innate and adaptive immune cells. More than 30 in vivo studies have reported on the use of human MSCs for the treatment of infectious diseases, with many more studies of animal MSCs in same-species models of infection. MSCs demonstrate potent antimicrobial effects against the major classes of human pathogens (bacteria, viruses, fungi, and parasites) across a wide range of infection models. Mechanistic studies have yielded important insight into their immunomodulatory and bactericidal activity, which can be enhanced through various forms of preconditioning. MSCs are being investigated in over 80 clinical trials for difficult-to-treat infectious diseases, including sepsis and pulmonary, intra-abdominal, cutaneous, and viral infections. Completed trials consistently report MSCs to be safe and well tolerated, with signals of efficacy against some infectious diseases. Although significant obstacles must be overcome to produce a standardized, affordable, clinical-grade cell therapy, these studies suggest that MSCs may have particular potential as an adjunct therapy in complex or resistant infections.
2019-07-31 | Experimental Therapy of Paracoccidioidomycosis Using P10-Primed Monocyte-Derived Dendritic Cells Isolated From Infected Mice
Paracoccidioidomycosis (PCM) is an endemic mycosis in Latin American caused by the thermodimorphic fungi of the genus Paracoccidioides spp. Notably, a Th1 immune response is required to control PCM. In this context, dendritic cells (DCs) seem to be essential players in capture, processing and presentation of Paracoccidioides antigens to naïve T cells and their further activation. We have previously demonstrated that differentiated DCs from bone marrow cells, pulsed with the immunoprotective peptide 10 (P10), effectively control experimental PCM immunocompetent and immunosuppressed mice. However, this procedure may not be infeasible or it is limited for the therapy of human patients. Therefore, we have sought a less invasive but equally effective approach that would better mimics the autologous transplant of DC in a human patient. Here, we isolated and generated monocyte differentiated dendritic cells (MoDCs) from infected mice, pulsed them with P-10, and used them in the therapy of PCM in syngeneic mice. Similar to the results using BMDCs, the P10-pulsed MoDCs stimulated the proliferation of CD4+ T lymphocytes, induced a mixed production of Th1/Th2 cytokines and decreased the fungal burden in murine lungs in the setting of PCM. The process of differentiating MoDCs derived from an infected host, and subsequently used for therapy of PCM is much simpler than that for obtaining BMDCs, and represents a more reasonable approach to treat patients infected with Paracoccidioides. The results presented suggest that P10-primed MoDC may be a promising strategy to combat complicated PCM as well as to significantly shorten the lengthy requirements for treatment of patients with this fungal disease.
2018-12-11 | Cell Wall Synthesis, Development of Hyphae and Metabolic Pathways Are Processes Potentially Regulated by MicroRNAs Produced Between the Morphological Stages of Paracoccidioides brasiliensis
MicroRNAs are molecules involved in post-transcriptional gene regulation. In pathogenic fungi, microRNAs have been described at different morphological stages by regulating targets involved in processes such as morphogenesis and energy production. Members of the Paracoccidioides complex are the main etiological agents of a systemic mycosis in Latin America. Fungi of the Paracoccidioides complex present a wide range of plasticity to colonize different niches. In response to environmental changes these fungi undergo a morphological switch, remodel their cellular metabolism and modulate structural cell wall components. However, the underlying mechanisms regulating the gene expression is not well understood. By using high performance sequencing and bioinformatics analyses, this work characterizes microRNAs produced by Paracoccidioides brasiliensis. Here, we demonstrated that the transcript encoding proteins involved in microRNA biogenesis were differentially expressed in each morphological stage. In addition, 49 microRNAs were identified in cDNA libraries with 44 differentially regulated among the libraries. Sixteen microRNAs were differentially regulated in comparison to the mycelium in the mycelium-to-yeast transition phase. The yeast parasitic phase revealed a complete remodeling of the expression of these small RNAs. Analyses of targets of the induced microRNAs, from the different libraries, revealed that these molecules may potentially regulate in the cell wall, by repressing genes involved in the synthesis and degradation of glucans and chitin. Furthermore, mRNAs involved in cellular metabolism and development were predicted to be regulated by microRNAs. Therefore, this work describes a putative post transcriptional regulation, mediated by microRNAs in P. brasiliensis and its influence on the adaptive processes of thermal dimorphic fungus.
small molecules
2026-08-14 | Pre-Exposure to Cyclosporine A Primes Paracoccidioides brasiliensis to Evade Host Immunity.
Paracoccidioidomycosis (PCM) is a systemic mycosis endemic to South America caused by thermodimorphic fungi of the genus Paracoccidioides, particularly P. brasiliensis. Calcineurin inhibition by cyclosporine A (CsA) perturbs fungal thermodimorphism and growth. Here, we asked whether pre-exposure of P. brasiliensis yeasts to CsA modulates host-pathogen interactions during infection. Mice infected with CsA-pre-exposed fungi exhibited significantly reduced levels of pro- and anti-inflammatory cytokines, along with decreased recruitment and activation of innate and adaptive immune cells at both time points. Although tissue inflammation and lesion areas were diminished, fungal burdens in lungs and liver were similar between groups. Importantly, yeasts recovered from lungs 72 h after infection with CsA-pretreated fungi displayed reduced in vitro colony growth, suggesting that prior CsA exposure induces a persistent slow-growth physiological state. This altered phenotype may impair effective immune recognition and inflammatory activation. As host immunosuppression was excluded in the experimental design, fungus-intrinsic phenotypes consistent with transient calcineurin pathway inhibition: altered growth/morphogenesis and putatively modified PAMP exposure that together blunt early immune activation. We interpret late-phase differences as downstream of these early pathway-dependent shifts rather than as heritable reprogramming. Overall, pre-exposure to CsA modulates P. brasiliensis-host interaction, dissociating tissue injury from fungal burden, highlights the role of calcineurin in fungal adaptation, and demonstrates how environmental exposure to bioactive compounds can influence fungal virulence and disease outcomes.
2026-08-07 | Novel antifungal agents for treating endemic mycoses: hope on the horizon?
Current treatments for endemic mycoses are limited by toxicity, drug-drug interactions, the need for therapeutic drug monitoring, and suboptimal penetration to sequestered sites. At the same time, several new antifungal strategies and agents are nearing clinical availability and may change practice. Current literature highlights limitations of standard therapy for histoplasmosis, coccidioidomycosis, blastomycosis, paracoccidioidomycosis, talaromycosis, sporotrichosis, and emergomycosis, which often rely on amphotericin B-based induction regimens followed by triazole antifungals. Emerging studies are evaluating single high-dose liposomal amphotericin B, shorter treatment durations for histoplasmosis, and flucytosine combined with amphotericin B-based induction for talaromycosis. Novel antifungals such as olorofim, fosmanogepix, and turletricin are especially promising, and treatment strategies guided by patient phenotypes and immune endotypes are also beginning to emerge. Growing evidence suggests therapy for endemic mycoses may change substantially in the near future. New drugs and alternative treatment approaches have the potential to improve safety, tolerability, oral availability, drug-drug interaction profiles, and treatment duration, with important implications for both clinical care and future research.
2026-06-08 | Disseminated paracoccidioidomycosis with a pulmonary-spine fistula: suggestive of contiguous spread.
Paracoccidioidomycosis (PCM) rarely involves the spine. We report a 55-year-old man with disseminated PCM presenting with thoracic spinal cord compression and an unprecedented pulmonary-spine fistula identified intraoperatively. Diagnosis was confirmed by histopathology and mycology. The patient underwent surgical decompression and stabilization followed by itraconazole, achieving complete neurological recovery. This case highlights a unique complication of PCM and supports combined surgical and antifungal management in cases with neurological compromise.
2026-03-11 | LC3-associated phagocytosis in macrophage responses to Paracoccidioides spp.
Paracoccidioidomycosis (PCM) is a systemic infection that is endemic to Latin America, caused by thermodimorphic fungi from the Paracoccidioides genus. These fungi are facultative intracellular parasites of macrophages. LC3-associated phagocytosis (LAP), a non-canonical form of autophagy, plays a critical role in the response of these phagocytes to similar pathogens. In this study, we investigated the role of LAP in the macrophage responses to Paracoccidioides spp. We detected LAP in macrophages infected with Paracoccidioides spp by immunofluorescence microscopy with antibodies to LC3. Piceatannol and diphenyleneiodonium chloride (DPI), respectively Syk and nicotinamide adenine dinucleotide phosphate oxidase (NADPH) inhibitors, were used to understand the role their pathways played. To determine the function of LAP, we targeted ATG5, a key autophagy gene, by RNA interference. We observed LC3 recruitment to phagosomes containing Paracoccidioides spp. in RAW264.7 and J774.16 cell lines and in bone marrow-derived macrophages. ATG5 RNA interference reduced the antifungal activity of J774.16 cells, highlighting the importance of LC3 recruitment for effective fungal control. Interestingly, pharmacological inhibition of Syk kinase and NADPH oxidase pathways, essential for LAP against Aspergillus fumigatus and Candida albicans, did not impair LAP against P. brasiliensis. This suggests distinct triggering mechanisms, possibly due to differences in the fungal cell surface composition. These findings suggest that LAP plays a significant role in the host defense against Paracoccidioides spp. and may represent a promising target for host-directed PCM therapies.
2026-03-01 | EPIDEMIOLOGICAL PROFILE OF DEATHS AMONG BRAZILIANS DUE TO PARACOCCIDIOIDOMYCOSIS BETWEEN 2013 AND 2023
Paracoccidioidomycosis is an endemic systemic mycosis and is among the ten leading causes of death from chronic and infectious diseases in Brazil. Its incidence ranges from 0.71 to 3.10 cases per 100,000 inhabitants per year in Brazil. In this context, this study aimed to analyze the epidemiological profile of deaths among Brazilians due to this disease between 2013 and 2023. Ecological study analyzing secondary data obtained from the Brazilian public health informatics platform (DATASUS), using the Mortality Information System (SIM). Data were included for paracoccidioidomycosis across Brazilian regions, considering the variables: sex, age group, ethnicity, and year of death from 2013 to 2023. Between 2013 and 2023, 774 deaths due to paracoccidioidomycosis were recorded in Brazil, distributed as follows: 105 in the North (13.5%), 367 in the Southeast (47.4%), 171 in the South (22.0%), 95 in the Central-West (12.2%), and 36 in the Northeast (4.6%). This indicates endemicity in the Southeast, which concentrated 47.4% (n = 367) of records. Regarding age group, there was predominance among individuals aged 50–59 years, with 226 deaths (29.2% of the total). Males were the most affected, accounting for 85.6% (n = 663) of confirmed cases. Regarding ethnicity, whites predominated with 51.0% (n = 395), followed by mixed race (“pardo”) with 35.1% (n = 272), Black with 10.3% (n = 80), Indigenous with 0.77% (n = 6), Asian with 0.38% (n = 3), and unknown with 2.3% (n = 18). In addition, the largest percentage increases in deaths were observed in almost all regions between 2018 and 2019 (15%) and between 2020 and 2021 (28%). These data reinforce that paracoccidioidomycosis is an important cause of mortality in Brazil, with endemicity in the Southeast and predominance among males, whites, and individuals aged 50–59 years. These findings indicate that prevention measures focused mainly on men and active screening in risk groups—considering both acute outbreaks and environmental exposure history—are essential. Understanding risk factors, exposure patterns, and immune response may help reduce disease burden, especially alongside improved reporting observed between 2020 and 2021.
vaccines
2024-10-06 | Nanoformulated CHO-rPb27 vaccine enhances immunity and controls infection, mitigating lung inflammation and dysfunction during experimental Paracoccidioidomycosis in mice.
Paracoccidioidomycosis (PCM) is a systemic mycosis caused by the dimorphic fungus within the genus Paracoccidioides, particularly Paracoccidioides brasiliensis. The traditional approach to treating this pulmonary infection involves prolonged therapy periods, ranging from weeks to years, often resulting in a notable frequency of disease relapse. Nanotechnology has emerged as a promising avenue for developing novel antifungal therapies and effective vaccines. This is attributed to its capability to facilitate targeted drug and antigen delivery, thereby mitigating toxicity and treatment expenses. This study investigates the synergistic properties of the CHO-rPb27 vaccine nanoformulation against experimental PCM. The therapeutic efficacy of CHO-rPb27 treatment is juxtaposed with the prophylactic protocol. Our findings demonstrate that both protocols effectively control P. brasiliensis pulmonary infection by eliciting a robust cellular and humoral immune response. This response attenuates chronic tissue damage and mitigates pulmonary mechanical dysfunction in mice.
2023-11-27 | Dectin-2 is critical for phagocyte function and resistance to Paracoccidioides brasiliensis in mice.
Germline-encoded pattern recognition receptors, particularly C-type lectin receptors (CLRs), are essential for phagocytes to sense invading fungal cells. Among CLRs, Dectin-2 (encoded by Clec4n) plays a critical role in the antifungal immune response as it recognizes high-mannose polysaccharides on the fungal cell wall, triggering phagocyte functional activities and ultimately determining adaptive responses. Here, we assessed the role of Dectin-2 on the course of primary Paracoccidioides brasiliensis systemic infection in mice with Dectin-2-targeted deletion. Paracoccidioides brasiliensis constitutes the principal etiologic agent of paracoccidioidomycosis, the most prominent invasive mycosis in Latin American countries. The deficiency of Dectin-2 resulted in shortened survival rates, high lung fungal burden, and increased lung pathology in mice infected with P. brasiliensis. Consistently, dendritic cells (DCs) from mice lacking Dectin-2 infected ex vivo with P. brasiliensis showed impaired secretion of several proinflammatory and regulatory cytokines, including TNF-α, IL-1β, IL-6, and IL-10. Additionally, when cocultured with splenic lymphocytes, DCs were less efficient in promoting a type 1 cytokine pattern secretion (i.e., IFN-γ). In macrophages, Dectin-2-mediated signaling was required to ensure phagocytosis and fungicidal activity associated with nitric oxide production. Overall, Dectin-2-mediated signaling is critical to promote host protection against P. brasiliensis infection, and its exploitation might lead to the development of new vaccines and immunotherapeutic approaches. We report a critical role of the innate immune receptor Dectin-2 during Paracoccidioides brasiliensis infection. Fungal sensing by Dectin-2 improved the survival of mice and lowered fungal burden. Further, Dectin-2 was required for cytokine production, phagocytosis, and fungal killing by phagocytes.
2021-11-01 | Identification of Potentially Therapeutic Immunogenic Peptides From Paracoccidioides lutzii Species.
Paracoccidioidomycosis (PCM) is an endemic mycosis in Latin America caused by the thermodimorphic fungi of the genus Paracoccidioides spp. Paracoccidioides lutzii (PL) is one of the 5 species that constitute the Paracoccidioides genus. PL expresses low amounts of glycoprotein (Gp) 43 (PLGp43) and PLGp43 displays few epitopes in common with the P. brasiliensis (PB) immunodominant antigen PBGp43, which is commonly used for serological diagnosis of PCM. This difference in structure between the glycoproteins markedly reduces the efficiency of serological diagnosis in patients infected with PL. We previously demonstrated that peptide 10 (P10) from the PBGp43 induces protective immune responses in in vitro and in vivo models of PB PCM. Since, P10 has proven to be a promising therapeutic to combat PB, we sought to identify peptides in PL that could similarly be applied for the treatment of PCM. PL yeast cell proteins were isolated from PL: dendritic cell co-cultures and subjected to immunoproteomics. This approach identified 18 PL peptides that demonstrated in silico predictions for immunogenicity. Eight of the most promising peptides were synthesized and applied to lymphocytes obtained from peptide-immunized or PL-infected mice as well as to in vitro cultures with peptides or dendritic cells pulsed the peptides. The peptides LBR5, LBR6 and LBR8 efficiently promoted CD4+ and CD8+ T cell proliferation and dendritic cells pulsed with LBR1, LBR3, LBR7 or LBR8 stimulated CD4+ T cell proliferation. We observed increases of IFN-γ in the supernatants from primed T cells for the conditions with peptides without or with dendritic cells, although IL-2 levels only increased in response to LBR8. These novel immunogenic peptides derived from PL will be employed to develop new peptide vaccine approaches and the proteins from which they are derived can be used to develop new diagnostic assays for PL and possibly other Paracoccidioides spp. These findings identify and characterize new peptides with a promising therapeutic profile for future against this important neglected systemic mycosis.
2020-09-18 | Medication association and immunomodulation: An approach in fungal diseases and in particular in the treatment of paracoccidioidomycosis.
Fungal infections have been increasing in recent decades, mainly affecting immunocompromised individuals, although certain mycoses, such as paracoccidioidomycosis (PCM), infect immunologically competent individuals. The major problems observed regarding fungal diseases are inadequate diagnosis, prolonged treatment time, the reduced number of drugs available for treatment, in addition to the fact that there are no vaccines for clinical use. Drug combination in order to immunomodulate the immune response is a new strategy used for the treatment of mycoses, since it is difficult to develop new antifungal drugs. The aim of this study is to present and analyze strategies recently suggested for the treatment of fungi of medical interest, in particular for PCM, such as the utilization of combinations of protein fractions or dead microorganisms, as vaccinal antigens, and cellular immunotherapy. We will also propose new therapeutic alternatives, such as lipids, vitamins, synthetic or natural products as well as the use of low intensity LASER therapy (LLLT) to modulate the immune response of the host, enhancing the efficiency of the existing treatments of mycoses of medical interest and in particular of PCM.
2019-11-26 | 43 kDa Glycoprotein (gp43) from Paracoccidioides brasiliensis Induced IL-17A and PGE2 Production by Human Polymorphonuclear Neutrophils: Involvement of TLR2 and TLR4.
The glycoprotein gp43 is the major antigenic/diagnostic component of Paracoccidioides brasiliensis , one of the etiologic agents of paracoccidioidomycosis (PCM). Gp43 has protective roles in mice, but due to adhesive properties, this glycoprotein has also been associated with immune evasion mechanisms. The present study evaluated gp43 interaction in vitro with Toll-like receptors 2 and 4 (TLR2 and TLR4) present in polymorphonuclear neutrophils (PMNs) from healthy human individuals and the consequent modulation of the immune response through the expression and release of cytokines and eicosanoids. PMNs were incubated in the absence or presence of monoclonal antibodies anti-TLR2 and anti-TLR4 (individually or in combination) before gp43 stimulation. Then, PMNs were analyzed for the expression of both surface receptors and the detection of intracytoplasmic IL-17A and IL-4 using flow cytometry, while the production of PGE2, LTB4, IL-6, IL-10, IL-12, IFN- γ , and TNF- α was evaluated in the supernatants by enzyme-linked immunosorbent assay (ELISA). Our results showed that gp43 increased TLR2 and TLR4 expression by PMNs and induced PGE2 and IL-17A via TLR4 and TLR2, respectively. Thus, our data suggest that gp43 from P. brasiliensis might modulate host susceptibility to the fungal infection by affecting PGE2 and IL-17A production.
antibodies
2026-01-23 | Single-cell RNA sequencing of CTLA-4 and PD-1 blockade in pulmonary paracoccidioidomycosis highlights a protective transcriptional program mediated by activated Th17 cells, neutrophils and macrophages
ABSTRACT Pulmonary paracoccidioidomycosis (PCM) relies on a finely balanced lung-immune network in which Th17, Treg, neutrophils, and macrophages orchestrate fungal control and tissue integrity. Furthermore, within the context of single-cell sequencing, little is known about how immune checkpoint inhibition modulates this balance during systemic mycosis. In a previous study we verified that the blockade of checkpoint molecules (CTLA-4 and PD-1) restores protective immunity that reduces fungal loads, tissue pathology and mortality of infected mice. Here, we have further studied this model by single-cell RNA sequencing on lung leukocytes from mice infected with Paracoccidioides brasiliensis and treated with anti-CTLA-4 or anti-PD-1 antibodies to define the cellular and molecular consequences of checkpoint blockade in vivo. We generated a high-resolution atlas covering T cells, neutrophils, macrophages/monocytes, B cells, NK cells, and epithelial subsets. Checkpoint inhibition consistently remodeled the CD4⁺ T cell compartment toward a Th17-enriched program, with reduced interleukin-10 expressing Treg frequencies and a prominent interleukin-17A⁺ (IL-17), C-C chemokine receptor type 2⁺, CXC chemokine (CXC) receptor type 6⁺, CD44⁺ ( Il17a ⁺ Ccr2 ⁺ Cxcr6 ⁺ Cd44 ⁺) signature. This shift was accompanied by the expansion and activation of neutrophils and macrophages expressing tumor necrosis factor and chemokines (including CXC motif chemokine ligand ( Cxcl 1, Cxcl2 and Ccl4 ), microbicidal-associated genes (S100 calcium-binding protein A8 and A9), and regulatory mediators such as secretory leukocyte protease inhibitor and interleukin-15. Ligand–receptor and trajectory analyses revealed a reinforced Th17–myeloid communication axis, particularly under CTLA-4 blockade, converging on IL17–centered inflammatory circuits while attenuating canonical Treg checkpoints (cytotoxic T-lymphocyte-associated protein 4, programmed cell death protein 1, interleukin-10). Together, these data demonstrate that anti-CTLA-4 and anti-PD-1 immunotherapies profoundly rewire the lung-immune microenvironment during PCM, amplifying effector Th17–neutrophil–macrophage networks that benefits protective antifungal activity Our work provides a mechanistic framework for evaluating immune checkpoint inhibitors in chronic fungal infections.
2025-11-03 | The Role of Myeloid-Derived Suppressor Cell (MDSC) in Fungal Infections and Its Potential as a Therapeutic Target.
The interaction between the immune system and fungi has long intrigued researchers, as fungi are among the most common organisms encountered by humans. Myeloid-derived suppressor cells (MDSCs) are specialized immune cells that play a key role in modulating immune responses during fungal infections by inhibiting T-cell activity. This review aims to investigate the mechanisms by which MDSCs influence fungal infections and to explore their potential as therapeutic targets. A comprehensive review of existing studies examining MDSC activity in various fungal infections was conducted. Comparative analysis focused on the protective versus non-protective effects of MDSCs across different fungal species. MDSCs suppress pro-inflammatory T-cell responses, leading to two contrasting outcomes. On one hand, this suppression mitigates disease progression by reducing harmful inflammation. On the other, it can enhance fungal survival by preventing T-cell-mediated damage. Protective effects of MDSCs have been observed in Candida albicans infections, whereas non-protective or detrimental effects have been reported in infections caused by Candida tropicalis, Paracoccidioides, Aspergillus fumigatus, Cryptococcus neoformans, Malassezia, and Mucor species. MDSCs play a dual role in fungal infections, balancing protective immune regulation with facilitation of fungal persistence. Understanding their mechanisms offers promising avenues for the development of targeted immunotherapies against fungal pathogens.
2024-09-20 | Paracoccidioides spp.: Escape mechanisms and their implications for the development of this mycosis.
Paracoccidioidomycosis (PCM) is a systemic granulomatous mycosis prevalent in individuals who carry out rural activities. Its etiological agent is a thermodimorphic fungus belonging to the genus; Paracoccidioides spp. Seven species of this fungus are known: Paracoccidioides brasiliensis, Paracoccidioides lutzii, Paracoccidioides americana, Paracoccidioides restrepiensis, Paracoccidioides venezuelensis, Paracoccidioides loboi and Paracoccidioides ceti. For a long time, Paracoccidioides brasiliensis was attributed as the only causal agent of this mycosis. What is known about adhesins, virulence, escape mechanisms and fungal involvement with the host's immune system is correlated with the species Paracoccidioides brasiliensis. Interactions between Paracoccidioides spp. and the host are complex and dynamic. The fungus needs nutrients for its needs and must adapt to a hostile environment, evading the host's immune system, thus enabling the development of the infectious process. On the other hand, the host's immune system recognizes Paracoccidioides spp. and employs all protective mechanisms to prevent fungal growth and consequently tissue invasion. Knowing this, understanding how Paracoccidioides spp. escapes the host's immune system, can help to understand the pathogenic mechanisms related to the development of the disease and, therefore, in the design of new specific treatment strategies. In this review we discuss these mechanisms and what are the adhesion molecules of Paracoccidioides spp. uses to escape the hostile environment imposed by the host's defense mechanisms; finally, we suggest how to neutralize them with new antifungal therapies.
2024-07-22 | MDSCs use a complex molecular network to suppress T-cell immunity in a pulmonary model of fungal infection.
Paracoccidioidomycosis (PCM) is a systemic endemic fungal disease prevalent in Latin America. Previous studies revealed that host immunity against PCM is tightly regulated by several suppressive mechanisms mediated by tolerogenic plasmacytoid dendritic cells, the enzyme 2,3 indoleamine dioxygenase (IDO-1), regulatory T-cells (Tregs), and through the recruitment and activation of myeloid-derived suppressor cells (MDSCs). We have recently shown that Dectin-1, TLR2, and TLR4 signaling influence the IDO-1-mediated suppression caused by MDSCs. However, the contribution of these receptors in the production of important immunosuppressive molecules used by MDSCs has not yet been explored in pulmonary PCM. We evaluated the expression of PD-L1, IL-10, as well as nitrotyrosine by MDSCs after anti-Dectin-1, anti-TLR2, and anti-TLR4 antibody treatment followed by P. brasiliensis yeasts challenge in vitro. We also investigated the influence of PD-L1, IL-10, and nitrotyrosine in the suppressive activity of lung-infiltrating MDSCs of C57BL/6-WT, Dectin-1KO, TLR2KO, and TLR4KO mice after in vivo fungal infection. The suppressive activity of MDSCs was evaluated in cocultures of isolated MDSCs with activated T-cells. A reduced expression of IL-10 and nitrotyrosine was observed after in vitro anti-Dectin-1 treatment of MDSCs challenged with fungal cells. This finding was further confirmed in vitro and in vivo by using Dectin-1KO mice. Furthermore, MDSCs derived from Dectin-1KO mice showed a significantly reduced immunosuppressive activity on the proliferation of CD4+ and CD8+ T lymphocytes. Blocking of TLR2 and TLR4 by mAbs and using MDSCs from TLR2KO and TLR4KO mice also reduced the production of suppressive molecules induced by fungal challenge. In vitro, MDSCs from TLR4KO mice presented a reduced suppressive capacity over the proliferation of CD4+ T-cells. We showed that the pathogen recognition receptors (PRRs) Dectin-1, TLR2, and TLR4 contribute to the suppressive activity of MDSCs by inducing the expression of several immunosuppressive molecules such as PD-L1, IL-10, and nitrotyrosine. This is the first demonstration of a complex network of PRRs signaling in the induction of several suppressive molecules by MDSCs and its contribution to the immunosuppressive mechanisms that control immunity and severity of pulmonary PCM.
2024-03-04 | Blocking the CTLA-4 and PD-1 pathways during pulmonary paracoccidioidomycosis improves immunity, reduces disease severity, and increases the survival of infected mice
Immune checkpoint pathways, i.e., coinhibitory pathways expressed as feedback following immune activation, are crucial for controlling an excessive immune response. Cytotoxic T lymphocyte antigen-4 (CTLA-4) and programmed cell death protein-1 (PD-1) are the central classical checkpoint inhibitory (CPI) molecules used for the control of neoplasms and some infectious diseases, including some fungal infections. As the immunosuppression of severe paracoccidioidomycosis (PCM), a chronic granulomatous fungal disease, was shown to be associated with the expression of coinhibitory molecules, we hypothesized that the inhibition of CTLA-4 and PD-1 could have a beneficial effect on pulmonary PCM. To this end, C57BL/6 mice were infected with Paracoccidioides brasiliensis yeasts and treated with monoclonal antibodies (mAbs) α-CTLA-4, α-PD-1, control IgG, or PBS. We verified that blockade of CTLA-4 and PD-1 reduced the fungal load in the lungs and fungal dissemination to the liver and spleen and decreased the size of pulmonary lesions, resulting in increased survival of mice. Compared with PBS-treated infected mice, significantly increased levels of many pro- and anti-inflammatory cytokines were observed in the lungs of α-CTLA-4-treated mice, but a drastic reduction in the liver was observed following PD-1 blockade. In the lungs of α-CPI and IgG-treated mice, there were no changes in the frequency of inflammatory leukocytes, but a significant reduction in the total number of these cells was observed. Compared with PBS-treated controls, α-CPI- and IgG-treated mice exhibited reduced pulmonary infiltration of several myeloid cell subpopulations and decreased expression of costimulatory molecules. In addition, a decreased number of CD4+ and CD8+ T cells but sustained numbers of Th1, Th2, and Th17 T cells were detected. An expressive reduction in several Treg subpopulations and their maturation and suppressive molecules, in addition to reduced numbers of Treg, TCD4+, and TCD8+ cells expressing costimulatory and coinhibitory molecules of immunity, were also detected. The novel cellular and humoral profiles established in the lungs of α-CTLA-4 and α-PD-1-treated mice but not in control IgG-treated mice were more efficient at controlling fungal growth and dissemination without causing increased tissue pathology due to excessive inflammation. This is the first study demonstrating the efficacy of CPI blockade in the treatment of pulmonary PCM, and further studies combining the use of immunotherapy with antifungal drugs are encouraged.
proteins
2025-01-10 | HIGH MOLECULAR MASS ANTIGENIC COMPONENTS OF PARACOCCIDIOIDES BRASILIENSIS: PARTIAL CHARACTERIZATION AND IMPLICATIONS IN THE TH1 RESPONSE
Paracoccidioidomycosis (PCM) is a chronic infection caused by the fungi Paracoccidioides brasiliensis or P. lutzii, whose host defense is mediated by Th1 lymphocytes. This study aimed to purify and evaluate the effect of high molecular mass (hMM) components of P. brasiliensis on the cellular immune response. The soluble antigens of the fungus (Pb18) were subjected to chromatography on a Sephadex G-200 column followed by HPLC, obtaining the fraction F17 (~380 kDa) and its subfraction F17-IV (~70 kDa), both reactive to sera from patients with PCM. The fractions were tested in vitro with splenic cells from infected mice, resulting in a lymphoproliferative response and increased levels of INF-γ and IL-10, without alteration of IL-4. These findings indicate the activation of the Th1 immune response and suggest that the ~380 kDa fraction can degrade to generate active subcomponents of ~70 kDa. The ~70 kDa subcomponent appears to be distinct from the gp70 described in the literature, given its ability to induce INF-γ. The results indicate the immunogenic potential of these components, highlighting their relevance for the development of vaccines or therapies against PCM.
2024-03-21 | Recombinant 60-kDa heat shock protein from Paracoccidioides brasiliensis induces the death of mouse lymphocytes in a mechanism dependent on Toll-like receptor 4 and tumor necrosis factor
Paracoccidioides fungi are thermodimorphic microorganisms that cause paracoccidioidomycosis (PCM), an autochthonous disease from Latin America, with most cases in Brazil. Humans become infected by inhaling conidia or mycelial fragments that transform into yeast at body temperature. These fungi cause chronic-granulomatous inflammation, which may promote fibrosis and parenchyma destruction in the lungs. In response to stress imposed by the host, fungi Paracoccidioides spp. increase the expression of heat shock proteins (HSP), which protect them by sustaining cellular proteostasis. Our group has studied the role of HSP60 in PCM, and previous data show that the recombinant HSP60 (rHSP60) has a deleterious effect when used in a single dose as therapy for experimental PCM. Here, we investigated the mechanism by which rHSP60 could worsen the disease. We found that rHSP60 caused the viability loss of splenic or lymph node cells from both immunized and non-immunized mice, including in splenic T lymphocytes under polyclonal stimulation with concanavalin A, probably by undergoing apoptosis. Among analyzed splenic cells, lymphocytes were indeed the main cells to die. When we investigated the death mechanisms, remarkably, we found that there was no viability loss in rHSP60-stimulated splenic cells from mice deficient in Toll-like receptor 4, TRIF adapter protein, and TNF receptor 1(TNFR1), as well as rHSP60-stimulated WT cells incubated with anti-TNF antibody. Besides, caspase-8 inhibitor IETD-CHO blocked the rHSP60 effect on splenic cells, suggesting that rHSP60 induces the extrinsic apoptosis pathway dependent on signaling via TLR4/TRIF and TNFR1.
2023-11-16 | Proteomic analysis reveals changes in the proteome of human THP-1 macrophages infected with Paracoccidioides brasiliensis
Paracoccidioides spp. is the etiologic agent of Paracoccidioidomycosis (PCM), a systemic disease with wide distribution in Latin America. Macrophages are very important cells during the response to infection by P. brasiliensis . In this study, we performed a proteomic analysis to evaluate the consequences of P. brasiliensis yeast cells on the human THP-1 macrophage proteome. We have identified 443 and 2247 upregulated or downregulated proteins, respectively, in macrophages co-cultured with yeast cells of P. brasiliensis in comparison to control macrophages unexposed to the fungus. Proteomic analysis revealed that interaction with P. brasiliensis caused metabolic changes in macrophages that drastically affected energy production pathways. In addition, these macrophages presented regulated many factors related to epigenetic modifications and gene transcription as well as a decrease of many proteins associated to the immune system activity. This is the first human macrophage proteome derived from interactions with P. brasiliensis , which contributes to elucidating the changes that occur during the host response to this fungus. Furthermore, it highlights proteins that may be targets for the development of new therapeutic approaches to PCM.
2023-02-12 | Biodistribution and Adjuvant Effect of an Intranasal Vaccine Based on Chitosan Nanoparticles against Paracoccidioidomycosis
Paracoccidioidomycosis (PCM) is a fungal infection caused by the thermodimorphic Paracoccidioides sp. PCM mainly affects the lungs, but, if it is not contained by the immune response, the disease can spread systemically. An immune response derived predominantly from Th1 and Th17 T cell subsets facilitates the elimination of Paracoccidioides cells. In the present work, we evaluated the biodistribution of a prototype vaccine based on the immunodominant and protective P. brasiliensis P10 peptide within chitosan nanoparticles in BALB/c mice infected with P. brasiliensis strain 18 (Pb18). The generated fluorescent (FITC or Cy5.5) or non-fluorescent chitosan nanoparticles ranged in diameter from 230 to 350 nm, and both displayed a Z potential of +20 mV. Most chitosan nanoparticles were found in the upper airway, with smaller amounts localized in the trachea and lungs. The nanoparticles complexed or associated with the P10 peptide were able to reduce the fungal load, and the use of the chitosan nanoparticles reduced the necessary number of doses to achieve fungal reduction. Both vaccines were able to induce a Th1 and Th17 immune response. These data demonstrates that the chitosan P10 nanoparticles are an excellent candidate vaccine for the treatment of PCM.
2023-01-06 | Role of paracoccin on Paracoccidioides brasiliensis virulence and susceptibility to antifungal drugs in the Galleria mellonella larvae model.
Paracoccin (PCN), a Paracoccidioides brasiliensis glycoprotein, has been reported to play roles in fungal biology and paracoccidioidomycosis pathogenesis. Lectin and chitinase domains account for the PCN's dual roles as an immunomodulatory agent and virulence factor. Soluble PCN injected in P. brasiliensis infected mice, by interacting with TLRs' N-glycans, drives the host immune response toward a protective Th1 axis. Otherwise, mice infection with yeasts overexpressing PCN (ov-PCN) revealed that PCN acts as a fungal virulence factor, thanks to its chitinase activity on the cell wall, resulting in resistance to phagocytes' fungicidal activity and development of severe paracoccidioidomycosis. Because antifungal drug administration follows the disease diagnosis, we studied the PCN effect on yeast resistance or susceptibility to antifungal agents. Using a paracoccidioidomycosis model developed in Galleria mellonella larvae, we confirmed the observation, in the murine host, that ov-PCN yeasts display maximum virulence compared to wild-type (wt-PCN) or PCN-silenced (kd-PCN) yeasts. PCN overexpression accounted for the highest susceptibility of P. brasiliensis to antifungal and reduced relative mRNA expression of genes encoding proteins related to cell wall remodeling. The lowest virulence, detected in infection with kd-PCN yeasts, correlated with the lowest susceptibility to antifungals and impact on genes for cell wall remodeling. So, we defined that the grade of endogenous PCN production influences the P. brasiliensis virulence and susceptibility to antifungal drugs, as well as the expression of genes related to cell wall remodeling. We postulate that this variable gene expression is mechanistically associated with P. brasiliensis virulence changes.
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2024-02-23 | Unveiling the functional significance of the 14.3.3 protein: A key player in Paracoccidioides brasiliensis biofilm formation.
Paracoccidioidomycosis (PCM) is a systemic mycosis caused by Paracoccidioides spp. The interaction mediated by the presence of adhesins on the fungal surface and receptors in the extracellular matrix of the host, as well as the biofilm formation, is essential in its pathogenesis. Adhesins such as gp43, enolase, GAPDH (glyceraldehyde-3-phosphate dehydrogenase), and 14-3-3 have been demonstrated in the Paracoccidioides brasiliensis (Pb18) strain and recognized as necessary in the fungus-host interaction. The Pb 18 strain silenced to 14-3-3 showed changes in morphology, virulence, and adhesion capacity. The study aimed to evaluate the role of adhesin 14-3-3 in P. brasiliensis biofilm formation and the differential expression of genes related to adhesins, comparing planktonic and biofilm forms. The presence of biofilm was also verified in sutures in vitro and in vivo. The silenced strain (Pb14-3-3 aRNA) was compared with the wild type Pb18, determining the differential metabolic activity between the strains by the XTT reduction assay; the biomass by violet crystal and the polysaccharides by safranin, even as morphological differences by microscopic techniques. Differential gene expression for adhesins was also analyzed, comparing the relative expression of these in planktonic and biofilm forms at different times. The results suggested that the silencing of 14-3-3 protein altered the ability to form biofilm and its metabolism. The quantity of biomass was similar in both strains; however, the formation of exopolymeric substances and polysaccharide material was lower in the silenced strain. Our results showed increased expression of enolase, GAPDH, and 14-3-3 genes in the first periods of biofilm formation in the Pb18 strain. In contrast, the silenced strain showed a lower expression of these genes, indicating that gene silencing can influence the expression of other genes and be involved in the biofilm formation of P. brasiliensis. In vitro and in vivo assays using sutures confirmed this yeast's ability to form biofilm and may be implicated in the pathogenesis of paracoccidioidomycosis.
2023-10-06 | Immunomodulatory Potential of Fungal Extracellular Vesicles: Insights for Therapeutic Applications
Extracellular vesicles (EVs) are membranous vesicular organelles that perform a variety of biological functions including cell communication across different biological kingdoms. EVs of mammals and, to a lesser extent, bacteria have been deeply studied over the years, whereas investigations of fungal EVs are still in their infancy. Fungi, encompassing both yeast and filamentous forms, are increasingly recognized for their production of extracellular vesicles (EVs) containing a wealth of proteins, lipids, and nucleic acids. These EVs play pivotal roles in orchestrating fungal communities, bolstering pathogenicity, and mediating interactions with the environment. Fungal EVs have emerged as promising candidates for innovative applications, not only in the management of mycoses but also as carriers for therapeutic molecules. Yet, numerous questions persist regarding fungal EVs, including their mechanisms of generation, release, cargo regulation, and discharge. This comprehensive review delves into the present state of knowledge regarding fungal EVs and provides fresh insights into the most recent hypotheses on the mechanisms driving their immunomodulatory properties. Furthermore, we explore the considerable potential of fungal EVs in the realms of medicine and biotechnology. In the foreseeable future, engineered fungal cells may serve as vehicles for tailoring cargo- and antigen-specific EVs, positioning them as invaluable biotechnological tools for diverse medical applications, such as vaccines and drug delivery.
2021-10-06 | Mesenchymal Stromal Cells: an Antimicrobial and Host-Directed Therapy for Complex Infectious Diseases
There is an urgent need for new antimicrobial strategies for treating complex infections and emerging pathogens. Human mesenchymal stromal cells (MSCs) are adult multipotent cells with antimicrobial properties, mediated through direct bactericidal activity and modulation of host innate and adaptive immune cells. More than 30 in vivo studies have reported on the use of human MSCs for the treatment of infectious diseases, with many more studies of animal MSCs in same-species models of infection. MSCs demonstrate potent antimicrobial effects against the major classes of human pathogens (bacteria, viruses, fungi, and parasites) across a wide range of infection models. Mechanistic studies have yielded important insight into their immunomodulatory and bactericidal activity, which can be enhanced through various forms of preconditioning. MSCs are being investigated in over 80 clinical trials for difficult-to-treat infectious diseases, including sepsis and pulmonary, intra-abdominal, cutaneous, and viral infections. Completed trials consistently report MSCs to be safe and well tolerated, with signals of efficacy against some infectious diseases. Although significant obstacles must be overcome to produce a standardized, affordable, clinical-grade cell therapy, these studies suggest that MSCs may have particular potential as an adjunct therapy in complex or resistant infections.
2019-07-31 | Experimental Therapy of Paracoccidioidomycosis Using P10-Primed Monocyte-Derived Dendritic Cells Isolated From Infected Mice
Paracoccidioidomycosis (PCM) is an endemic mycosis in Latin American caused by the thermodimorphic fungi of the genus Paracoccidioides spp. Notably, a Th1 immune response is required to control PCM. In this context, dendritic cells (DCs) seem to be essential players in capture, processing and presentation of Paracoccidioides antigens to naïve T cells and their further activation. We have previously demonstrated that differentiated DCs from bone marrow cells, pulsed with the immunoprotective peptide 10 (P10), effectively control experimental PCM immunocompetent and immunosuppressed mice. However, this procedure may not be infeasible or it is limited for the therapy of human patients. Therefore, we have sought a less invasive but equally effective approach that would better mimics the autologous transplant of DC in a human patient. Here, we isolated and generated monocyte differentiated dendritic cells (MoDCs) from infected mice, pulsed them with P-10, and used them in the therapy of PCM in syngeneic mice. Similar to the results using BMDCs, the P10-pulsed MoDCs stimulated the proliferation of CD4+ T lymphocytes, induced a mixed production of Th1/Th2 cytokines and decreased the fungal burden in murine lungs in the setting of PCM. The process of differentiating MoDCs derived from an infected host, and subsequently used for therapy of PCM is much simpler than that for obtaining BMDCs, and represents a more reasonable approach to treat patients infected with Paracoccidioides. The results presented suggest that P10-primed MoDC may be a promising strategy to combat complicated PCM as well as to significantly shorten the lengthy requirements for treatment of patients with this fungal disease.
2018-12-11 | Cell Wall Synthesis, Development of Hyphae and Metabolic Pathways Are Processes Potentially Regulated by MicroRNAs Produced Between the Morphological Stages of Paracoccidioides brasiliensis
MicroRNAs are molecules involved in post-transcriptional gene regulation. In pathogenic fungi, microRNAs have been described at different morphological stages by regulating targets involved in processes such as morphogenesis and energy production. Members of the Paracoccidioides complex are the main etiological agents of a systemic mycosis in Latin America. Fungi of the Paracoccidioides complex present a wide range of plasticity to colonize different niches. In response to environmental changes these fungi undergo a morphological switch, remodel their cellular metabolism and modulate structural cell wall components. However, the underlying mechanisms regulating the gene expression is not well understood. By using high performance sequencing and bioinformatics analyses, this work characterizes microRNAs produced by Paracoccidioides brasiliensis. Here, we demonstrated that the transcript encoding proteins involved in microRNA biogenesis were differentially expressed in each morphological stage. In addition, 49 microRNAs were identified in cDNA libraries with 44 differentially regulated among the libraries. Sixteen microRNAs were differentially regulated in comparison to the mycelium in the mycelium-to-yeast transition phase. The yeast parasitic phase revealed a complete remodeling of the expression of these small RNAs. Analyses of targets of the induced microRNAs, from the different libraries, revealed that these molecules may potentially regulate in the cell wall, by repressing genes involved in the synthesis and degradation of glucans and chitin. Furthermore, mRNAs involved in cellular metabolism and development were predicted to be regulated by microRNAs. Therefore, this work describes a putative post transcriptional regulation, mediated by microRNAs in P. brasiliensis and its influence on the adaptive processes of thermal dimorphic fungus.
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