Activation of α7nAChR Preserves Intestinal Barrier Integrity and Ameliorates Cholestasis Liver Fibrosis in Mice by Enhancing the HO-1 / STAT3 Signaling to Inhibit NF-κB Activation

Abstract

Background: Activation of alpha-7 nicotinic acetylcholine receptor (α7nAChR) can inhibit the systemic inflammatory response and preserve intestinal barrier integrity. This study aimed at elucidating the molecular mechanisms by which α7nAChR activation could inhibit intestinal barrier injury and cholestatic liver fibrosis in mice induced by bile duct ligation (BDL).Methods: The intestine-specific HO-1 knockout VillinCreHmox1-/- and control Hmox1floxp/floxp C57BL/6 mice were subjected to BDL. The therapeutic effects of GST-21, a specific ligand for α7nAChR, on systemic and intestinal inflammation, intestinal barrier integrity, liver fibrosis and injury, HO-1 expression, STAT3, AKT and NF-kBp65 activation were examined in these mice and intestinal epithelial cells co-cultured with macrophages. Results: Compared with BDL mice, α7nAChR activation by GST-21 decreased intestinal and liver injury and fibrosis in BDL mice, accompanied by reducing serum cytokine responses. In addition, activation of α7nAChR preserved the tight junction protein expression and intestinal epithelial cell barrier integrity in BDL mice and epithelial cells co-cultured with macrophages. The therapeutic effects of α7nAChR activation were mediated by enhancing HO-1 expression, STAT3 phosphorylation, and reducing the NF-kBp65 activation in intestinal tissues and epithelial cells co-cultured with macrophages. Finally, activation of α7nAChR induced HO-1 expression and STAT3 phosphorylation in an interdependent manner, independent of the PI3K/AKT signaling. Conclusion: Activation of α7nAChR enhanced HO-1 expression and STAT3 signaling to inhibit NF-κB activation, preserving the intestinal barrier integrity, and reducing inflammation and liver fibrosis in cholestasis mice. Therefore, targeting α7nAChR may be a promising interventional strategy for primary biliary cholangitis.