Objective:To investigate the mechanism of improving liver injury by enhancing the abundance of Akkermansia mu-ciniphila(AKK bacteria)with hepatocyte-specific Yap1 knockout during PD-1 monoclonal antibody treatment.Methods:Hepatocyte-specific Yap1 knockout mice(genotype Yap1Flox/Flox;albumin-Cre,labeled as Yap1LKO)and control mice(genotype Yap1Flox/Flox,labeled Yap1Flox),aristolocholic acidⅠ(AAⅠ)and CCl4 were used to induce liver injury,Yap1LKO mice and Yap1Flox mice were randomly di-vided into control group and PD-1 monoclonal antibody group.After the intervention,real-time PCR detected changes in the abun-dance of AKK bacteria in the fecal microbial DNA of mice,16S rRNA gene sequencing further analyzes intestinal flora changes,the livers of mice were made into wax blocks for HE staining to observe the histopathological changes of the liver.Results:Yap1Flox mice exhibited balloon-like edema degeneration of hepatocytes and infiltration of inflammatory factors in the manifold area,compared with Yap1Flox mice,Yap1LKO mice had reduced the abundance of AKK bacteria in the intestine,fibrosis of the liver,and the degree of dam-age was more serious;PD-1 monoclonal antibody treatment alone did not increase the abundance of AKK bacteria in the intestines of mice,and fibrosis appeared in the liver;however,the abundance of intestinal AKK bacteria in Yap1LKO mice treated with PD-1 mono-clonal antibody increased,the ratio(F/B value)of Firmicutes to Bacteroides at the phylum level decreased,and the morphology of he-patocytes returned to normal and the degree of liver damage decreased.Conclusion:In AAⅠ and CCl4 induced liver injury mice,he-patocyte-specific Yap1 knockout reduced the abundance of AKK bacteria in the intestine,and the degree of liver injury was more se-vere than that in Yap1Flox mice.When treated with PD-1 monoclonal antibody,hepatocyte-specific Yap1 knockout could increase the abundance of AKK bacteria in the intestine,change the composition of intestinal flora,maintain intestinal homeostasis and ameliorate liver injury.

Objective:To investigate the mechanism of improving liver injury by enhancing the abundance of Akkermansia mu-ciniphila(AKK bacteria)with hepatocyte-specific Yap1 knockout during PD-1 monoclonal antibody treatment.Methods:Hepatocyte-specific Yap1 knockout mice(genotype Yap1Flox/Flox;albumin-Cre,labeled as Yap1LKO)and control mice(genotype Yap1Flox/Flox,labeled Yap1Flox),aristolocholic acidⅠ(AAⅠ)and CCl4 were used to induce liver injury,Yap1LKO mice and Yap1Flox mice were randomly di-vided into control group and PD-1 monoclonal antibody group.After the intervention,real-time PCR detected changes in the abun-dance of AKK bacteria in the fecal microbial DNA of mice,16S rRNA gene sequencing further analyzes intestinal flora changes,the livers of mice were made into wax blocks for HE staining to observe the histopathological changes of the liver.Results:Yap1Flox mice exhibited balloon-like edema degeneration of hepatocytes and infiltration of inflammatory factors in the manifold area,compared with Yap1Flox mice,Yap1LKO mice had reduced the abundance of AKK bacteria in the intestine,fibrosis of the liver,and the degree of dam-age was more serious;PD-1 monoclonal antibody treatment alone did not increase the abundance of AKK bacteria in the intestines of mice,and fibrosis appeared in the liver;however,the abundance of intestinal AKK bacteria in Yap1LKO mice treated with PD-1 mono-clonal antibody increased,the ratio(F/B value)of Firmicutes to Bacteroides at the phylum level decreased,and the morphology of he-patocytes returned to normal and the degree of liver damage decreased.Conclusion:In AAⅠ and CCl4 induced liver injury mice,he-patocyte-specific Yap1 knockout reduced the abundance of AKK bacteria in the intestine,and the degree of liver injury was more se-vere than that in Yap1Flox mice.When treated with PD-1 monoclonal antibody,hepatocyte-specific Yap1 knockout could increase the abundance of AKK bacteria in the intestine,change the composition of intestinal flora,maintain intestinal homeostasis and ameliorate liver injury.

Objective To construct the expression vector and express the recombinant human L-selectin in prokaryotic system, and purify the aimed protein for the preparation of rabbit anti-human L-selectin polyclonal antibody. Methods The partial cDNA of human L-selectin was amplified from the open reading frame (ORF) of N-terminus sequence of L-selectin containing 153 amino acids by PCR, then cloned into the prokaryotic expression vector pQE40 at restriction sites BamH Ⅰ and Hind Ⅲ. The recombinant expression plasmid pQE40-L-selectin was transformed into E. coli M15 for expression. The fusion protein including 6-His-tag was purified by Ni-NTA chromatographic column and analysed by SDS-PAGE. The purified protein was used to immune rabbit for preparing polyclonal antibody. Western blotting analysis and dot immunoblot assay (DIBA) were used to test the titer of the antiserum. Results The expression plasmid pQE40-L-selectin was constructed and confirmed with restriction enzyme digestion. The quantity of the purified protein from E. coli M15 was 600 mg ? L-1. By immuning the rabbit, the polyclonal antibody was successfully prepared. The results of dot immunoblot assay (DIBA) showed that the antiserum had the high titer (1 : 1 000). Conclusion The recombinant human L-seleclin prolein can express with high efficiency in E. coli M15. The prepared polyclonal antibody has a high titer.