Society: AASLD

Aims: The mechanism of gut microbiota involved in the etiopathogenesis of primary cholangitis (PBC) remains unclear. Here, we investigated the role of gut microbiota in liver immune response in PBC.
Methods: Female C57BL6/J mice (n=8 per group) were gavaged with placebo, feces from healthy controls or PBC patients after antibiotic cocktails. Alpha-naphthylisothiocyanate (ANIT) was given to induce cholestasis. The liver, mesenteric lymph node (MLN) and spleen of mice were cultured under anaerobic and aerobic conditions. Serum, intestinal and liver tissues were isolated for ELISA, histology, real-time PCR and flow cytometry analysis. Fecal and liver biopsies from PBC patients (n = 14) and healthy controls (n = 5) were collected to confirm the distribution of Klebsiella pneumonia and T helper 17 (Th17) infiltration. The liver biopsies from early and advanced PBC patients (n = 13) were isolated for RNA-seq. Immortalized Human Intrahepatic Biliary Epithelial Cells (HIBEpiCs) were used for investigation the effect of K. pneumonia on the chemotaxis of Th17.
Results: More severe liver injuries and Th17 cell infiltration were found in mice gavaged by feces from PBC patients than control. Denser Th17 cells was observed in liver of PBC group after ANIT treatment (P < 0.05). K. pneumonia was isolated from the liver, spleen and MLN of the PBC group mice. Interestingly, administration of feces from PBC patients increased serum endotoxin and impairment of the intestinal epithelial barrier (P < 0.05). Antibiotic treatment significantly decreased Th17 infiltration, intestinal epithelial barrier and liver injury induced by PBC-derived microbiota. Besides, K. pneumoniae monocolonization can induce K. pneumoniae translocation and inflammatory cell infiltration in liver. Furthermore, PBC patients showed increased of CCL20 expression and infiltration Th17 cells in liver, which was positively correlated with disease progression. Notably, the abundance of K. pneumoniae was increased in the liver and fecal of PBC patients. In vitro, the bacterial lysate of K. pneumoniae upregulated cholangiocyte senescence and CCL20 in HIBEpiCs in a concentration-dependent manner.
Conclusions: We demonstrate that K. pneumoniae translocation to liver increased CCL20 secretion promote Th17 immune response in PBC.

Ying Ran

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