Intestinal microecology regulates neutrophil recruitment through TLR4/MAPK/CXCR2 signaling pathway to promote liver ischemia/reperfusion injury.

Liver ischemia/reperfusion injury (IRI) is a major complication of hemorrhagic shock, hepatectomy and liver transplantation. Intestinal microecology has momentous functions in various human diseases. The present study aimed to elucidate the role and underlying mechanism of intestinal microecology in liver IRI. A liver IRI mouse model was constructed and validated using hematoxylin and eosin staining, enzyme-linked immunosorbent assay and Naphthol AS-D chloroacetate esterase staining. The function of intestinal microecology in liver IRI was evaluated using flow cytometry and western blot analysis. Moreover, the mechanisms of intestinal microecology in liver IRI were assessed using a series of molecular experiments. The results revealed that liver IRI associated with intestinal microecology dysbiosis exhibited increased hepatic neutrophil infiltration, MAPK pathway activation and inflammatory cytokine production. The 16 S rRNA gene sequencing of fecal samples from Sham, IRI, IRI+antibiotic pre-treatment and fecal transplantation (FT) groups revealed microbial community alterations, with shifts in Bacteroidota and Firmicutes abundance associated with liver injury and neutrophil recruitment. PCA, PCoA and taxonomic profiling further confirmed group-dependent remodeling of the gut microbial community. FT using fecal microbiota from IRI donor mice exacerbated liver neutrophil infiltration, MAPK/CXCR2 activation and inflammatory responses, whereas TAK-242-mediated TLR4 blockade attenuated these effects. Overall, the present study suggests that gut microbiota dysbiosis may enhance liver IRI by promoting neutrophil recruitment, at least in part through the TLR4/MAPK/CXCR2 axis, revealing a novel microbe-immune-liver interaction that may be targeted therapeutically.