Shengjiang San attenuates sepsis-induced acute intestinal injury via Lactobacillus murinus derived IAAld-mediated macrophage polarization through NF-κB and TGF-β signaling.

Abstract

ETHNOPHARMACOLOGY ASSOCIATED: Sepsis is a life-threatening condition triggered by a dysregulated host response to infection, characterized by uncontrolled systemic inflammation and often culminating in multiple organ damage. Shengjiang San (SJS), a classic traditional Chinese medicinal (TCM) formula, has been historically utilized for its efficacy in removing heat, resolving toxicity, and reducing inflammation. Nevertheless, the precise role and mechanisms through which SJS modulates inflammatory responses and protects against sepsis-induced multi-organ injury are not yet fully understood. OBJECTIVE: To investigate the protective mechanisms of SJS that improve sepsis-induced acute intestinal injury (SAII) by modulating the abundance and metabolism of the gut microbiota. METHODS: A sepsis animal model was established using cecal ligation and puncture. The protective effects of SJS in SAII were evaluated through behavioral assessments, enzyme-linked immunosorbent assay, histological examination, and immunofluorescence analysis. Fecal samples were subjected to 16S rRNA sequencing and non-targeted metabolomics to identify probiotic taxa and metabolites associated with SJS administration. Proteomic analysis integrated with network pharmacology was performed to explore the underlying mechanisms. Fecal microbiota transplantation (FMT) and microbial metabolite analysis were utilized to elucidate the potential mechanism. RESULTS: SJS was observed to significantly improve clinical scores, reduce pro-inflammatory cytokines, including IL-6, TNF-α and IL-1β. SJS also restored integrity of the intestinal barrier by upregulating the expression of ZO-1 and Claudin-1. 16S rRNA sequencing analysis demonstrated that SJS induced significant restructuring of the gut microbiota, including a marked increase in Lactobacillus murinus (L.M.) abundance. Proteomic and network pharmacological analyses revealed that SJS was protected against SAII by inhibiting NF-κB-mediated M1 polarization while promoting TGF-β-mediated M2 polarization. In particular, this protective effect was found to depend on the abundance of L.M., which regulated intestinal inflammation through its specific metabolites, indoleacetaldehyde (IAAld). CONCLUSION: SJS improves SAII by orchestrating L.M. derived IAAld-mediated macrophage polarization through modulation of NF-κB and TGF-β signaling pathways.