• Takahiro Nishio, Kojiro Taura, Keiko Iwaisako, Yukinori Koyama, Kazutaka Tanabe, Gen Yamamoto, Yukihiro Okuda, Yoshinobu Ikeno, Kenji Yoshino, Yosuke Kasai, Masayuki Okuno, Satoru Seo, Takaki Sakurai, Masataka Asagiri, Etsuro Hatano, and Shinji Uemoto.
• Department of Surgery, Graduate School of Medicine, Kyoto University, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto, Japan.
• J. Gastroenterol. 2017 Aug 1; 52 (8): 965-976.

BackgroundNonalcoholic fatty liver disease ranges from simple steatosis to nonalcoholic steatohepatitis (NASH). Kupffer cells play a central role in promoting hepatic inflammation, which leads to the development of NASH. We investigated the anti-inflammatory effect of hepatic vagus-mediated stimulation of the α7 nicotinic acetylcholine receptor (α7nAChR) on Kupffer cells in NASH pathogenesis.MethodsWild-type (WT) mice undergoing hepatic vagotomy (HV) were fed a methionine- and choline-deficient (MCD) diet for 1 week. α7nAChR knockout (α7KO) chimeric mice were generated by transplanting α7KO bone marrow cells into irradiated and Kupffer cell-deleted WT recipients. Kupffer cells were isolated from WT mice and treated with α7nAChR agonist under stimulation by lipopolysaccharide and/or palmitic acid.ResultsHV aggravated MCD diet-induced NASH in both steatosis and inflammation. The hepatic inflammatory response, including the upregulation of tumor necrosis factor alpha (TNFα), interleukin (IL)-12, and monocyte chemoattractant protein 1 (MCP-1), was accelerated in HV mice, accompanied by the downregulation of PPARα pathway genes. Kupffer cells were highly activated via the phosphorylation and nuclear translocation of nuclear factor-kappa B (NF-κB) in MCD diet-fed HV mice. The α7nAchR agonist suppressed the inflammatory response of primary Kupffer cells induced by lipopolysaccharide and palmitic acid by attenuating the NF-κB cascade. α7KO chimeric mice fed an MCD diet for 1 week developed advanced NASH with highly activated Kupffer cells. The hepatic expression of TNFα, IL-12, and MCP-1 was upregulated in α7KO chimeric mice, accompanied by abnormal lipid metabolism.ConclusionsHepatic vagus activity regulates the inflammatory response of Kupffer cells via α7nAChR in NASH development.

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