Exploring the mechanism of intestinal bacterial translocation after severe acute pancreatitis: the role of Toll-like receptor 5.

Severe acute pancreatitis (SAP)-induced intestinal bacterial translocation and enterogenic infection are among the leading causes of mortality in patients. However, the mechanisms by which SAP disrupted the intestinal barrier and led to bacterial translocation remained unclear. Therefore, we employed multi-omics analysis including microbiome, metabolome, epigenome, transcriptome, and mass cytometry (CyTOF) to identify potential targets, followed by functional validation using transgenic mice. The integrated multi-omics analysis primarily indicated overgrowth of intestinal flagellated bacteria, upregulation of intestinal Toll-like receptor 5 (TLR5) and acute inflammatory response, and increased infiltration of intestinal high-expressing TLR5 lamina propria dendritic cells (TLR5(hi) LPDC) after SAP. Subsequently, intestinal flagellin-TLR5 signaling was activated after SAP. Intestinal barrier disruption, bacterial translocation, and helper T cells (Th) differentiation imbalance caused by SAP were alleviated in TLR5 knocked out (Tlr5(-/-)) or conditionally knocked out on LPDC (Tlr5(ΔDC)) mice. However, TLR5 conditional knockout on intestinal epithelial cells (Tlr5(ΔIEC)) failed to improve SAP-induced bacterial translocation. Moreover, depletion of LPDC and regulatory T cells (Treg) ameliorated bacterial translocation after SAP. Our findings identify TLR5 on LPDC as a potential novel target for preventing or treating intestinal bacterial translocation caused by SAP.