Metabolic shifts in tryptophan pathways during acute pancreatitis infections.

Infectious complications (ICs) in acute pancreatitis (AP) are primarily driven by intestinal bacterial translocation, significantly increasing mortality and hospital stays. Despite this, the role of the gut microenvironment, particularly its metabolic aspects, in AP remains poorly understood. In this study, we investigated a cohort of patients with AP, and conducted supplemental murine studies, to explore the relationship between the gut metabolome and the development of ICs. Metabolomic analysis revealed that disruptions in gut tryptophan metabolism - especially reductions in serotonin and indole pathways - are key features associated with IC occurrence. Additionally, elevated plasma levels of tryptophan metabolites within the kynurenine pathway were identified as valuable predictive biomarkers for ICs. Mechanistic studies in murine models demonstrated that an impaired intestinal Th17 response, modulated by these tryptophan metabolites, plays a critical role in IC development. Serotonin supplementation enhanced Th17 responses, reducing IC incidence, while administration of kynurenic acid, a kynurenine metabolite, exacerbated pancreatic infections, potentially through immunosuppressive effects. These findings highlight the pivotal role of tryptophan metabolites in AP pathogenesis, emphasizing their potential as both predictive markers and therapeutic targets in IC management.