Y. Liu1, T. Liu1, V. Robin1, A. Fatemeh1, C. Paul1, F. Matthew1, R. Hodin1, R. Hodin1 1Massachusetts General Hospital,Department Of Surgery,Boston, MA, USA
Introduction:
Biliary cirrhosis can result from many conditions including sclerosing cholangitis, malignancy, or benign biliary obstruction. Mice undergoing common bile duct ligation (CBDL) have been shown to have impaired intestinal barrier function, bacteria overgrowth, and liver fibrosis. Interestingly, the process of liver fibrosis is ameliorated with depletion of intestinal bacteria. Intestinal alkaline phosphatase (IAP) is an enzyme located on the brush border of intestinal epithelial cells and released into the gut lumen and has been shown to both detoxify LPS and maintain the intestinal barrier through upregulating tight junctions. We hypothesized that IAP may protect against liver fibrosis in a CBDL model.
Methods:
Adult (WT and IAP KO) mice were subjected to either sham or bile duct ligation (+/- IAP in their drinking water) and sacrificed for tissue harvest after 1 and 3 weeks.
Results:
Compared to sham controls, stool IAP activity, AKP3, and AKP6 mRNA expression were significantly decreased after CBDL both at 1 week (sham vs. CBDL: 114.56 vs. 27.50; 1 vs. 0.36; 1 vs. 0.64) and 3 weeks (sham vs. CBDL: 114.56 vs. 32.97, 1 vs. 0.58; 1 vs. 0.69). Additionally, ZO-1, ZO-2 and Occludin mRNA expression were decreased (sham to CBDL 1 week: 1 vs. 0.71, 1 vs. 0.58, 1 vs. 0.65; 3 weeks: 1 vs. 0.64, 1 vs. 0.54, 1 vs. 0.60), Gut barrier function became impaired after CBDL as determined by FITC-Dextran assay (sham to CBDL 1 week: 156.12 vs. 70.92 pg/ml). IAP treatment maintained tight junction protein gene expression in the CBDL mice (sham vs. CBDL 3 weeks: 1 vs. 1.22, 1 vs. 0.92, 1 vs. 1.07). In regard to the effect of IAP on CBDL induced liver fibrosis, we found that liver ACAT, Collagen I, TIMP, and TGF-b mRNA expression were increased in IAP KO compared to WT mice (4.87 vs. 9.67; 47.74 vs. 122.69; 49.55 vs. 70.12; 2.40 vs. 4.37). Furthermore, enteral IAP supplementation decreased expression of these genes in both WT and IAP KO mice 3 weeks after CBDL(WT mice: 2.97, 28.48, 28.67, 1.79; KO mice: 2.89, 28.40, 35.27, 2.89).
Conclusion:
Bile duct ligation may lead to intestinal barrier dysfunction by decreasing IAP levels, and further increasing the liver fibrosis process. Oral IAP may represent a novel therapy against liver fibrosis.