2026-06-10 | De novo Crohn's Disease Treated with Ustekinumab in a Pediatric Liver Transplant Recipient with Tyrosinemia: A Case Report.
De novo inflammatory bowel disease (IBD) is more frequent in transplant recipients than in the general population and should be considered in the differential diagnosis of chronic diarrhea. In pediatric liver transplant recipients, an incidence of 206 vs. 20 cases per 100,000 patient-years has been reported, suggesting an underrecognized complication of immunosuppression. We report an 11-year-old girl with tyrosinemia type 1 who underwent liver transplantation and later developed de novo Crohn's disease. Despite maintenance therapy with tacrolimus, methylprednisolone, and everolimus, she presented with chronic diarrhea, weight loss, and elevated inflammatory markers after several episodes of Clostridioides difficile infection treated with oral vancomycin and only transient improvement. Initial inflammatory markers were only mildly elevated but showed a progressive rise over 18 months despite antibiotic therapy, alongside positive ASCA IgG and ASCA IgA with negative pANCA at the time of formal evaluation. Colonoscopy showed patchy aphthous and serpiginous ulcers with a cobblestone appearance, and histology revealed cryptitis and a mixed lymphoplasmacytic infiltrate without granulomas. Magnetic resonance enterography demonstrated ileocolic inflammation with wall thickening and mesenteric vessel engorgement. Infectious and drug-induced colitis and Epstein-Barr virus-related disease were excluded, and de novo ileocolic Crohn's disease (Paris A1b L3 B1 G1) was diagnosed. Ustekinumab (260 mg intravenously, then 90 mg subcutaneously every 4 weeks) was added to baseline immunosuppression, inducing clinical remission with normalization of C-reactive protein and a decrease in fecal calprotectin to 10 µg/g by week 20, sustained at 18 months with preserved graft function. This case illustrates the diagnostic challenges of de novo Crohn's disease in pediatric liver transplant recipients with metabolic liver disease and supports ustekinumab as a safe and effective option when other biologics are limited by prior infectious or lymphoproliferative.
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2026-06-02 | An optimized engineered bacterium for tyrosinemia type 1 therapy: A multi-species preclinical study.
Hereditary tyrosinemia type 1 (HT1) is a life-threatening metabolic disorder caused by the toxic accumulation of tyrosine and its metabolites. While treatment with 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC) combined with a strict dietary regimen has improved outcomes, it imposes a significant lifelong burden and is associated with debilitating side effects and incomplete protection. Here, we developed an engineered probiotic with an optimized design, e-EcN-HT, and demonstrated its comprehensive efficacy and safety in HT1 across multiple animal models, including fumarylacetoacetate hydrolase (FAH)-/- mice, FAH-/- rabbits, and Bama minipigs. Our findings indicate that e-EcN-HT not only mitigates multifaceted acute manifestations of FAH-/- mice, including neonatal death and acute liver injury, but also improves chronic liver lesions when combined with NTBC. The therapeutic effect translated successfully to the FAH-/- rabbit model. Moreover, e-EcN-HT administration led to rapid metabolism of orally administered 13C-tyrosine, confirming robust and active tyrosine consumption in pigs. Comprehensive safety assessments across murine and porcine models showed that e-EcN-HT was well tolerated, with no significant adverse effects, systemic dissemination, or detrimental disruption to the resident gut microbiota. Collectively, our multi-species preclinical data underscore the potential of engineered bacteria as a viable therapeutic strategy for HT1 and possibly other metabolic disorders.
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2026-05-12 | Rational Design of Small-Molecule Stabilizers of Human Fumarylacetoacetate Hydrolase for the Treatment of Tyrosinemia Type I.
Hereditary tyrosinemia type 1 (HT1) stems from the loss of fumarylacetoacetate hydrolase (FAH) activity, causing severe liver-kidney disease. Nitisinone does not restore FAH function and carries metabolic and dietary burdens. Here, we used an integrated workflow guided by X-ray structures of human FAH to obtain small-molecule pharmacological chaperones that bind with low-μM affinity and stabilize FAH. Hits were validated by NMR and isothermal titration calorimetry. Protein stabilization was assessed by DOSY-NMR and circular dichroism; functional effects were tested in FAH activity assays, a CRISPR-engineered cellular model, and testing in an animal model of HT1. Compounds shifted the G337S pathological variant toward the active dimer and slowed unfolding/aggregation, resulting in dose-dependent enhancement of FAH activity and partial rescue of FAH homeostasis in cells and the liver tissue of a mouse model of HT1. These molecules support a therapeutic approach that could complement nitisinone in HT1.
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