リポポリサッカライドの外因性投与はコリン欠乏 L-アミノ酸置換食誘発脂肪性肝炎モデルマウスにおいて肝線維化を促進する

Various rodent models have been proposed for basic research; however, the pathogenesis of human nonalcoholic steatohepatitis (NASH) is difficult to closely mimic. Lipopolysaccharide (LPS) has been reported to play a pivotal role in fibrosis development during NASH progression via activation of toll-like receptor 4 (TLR4) signaling. This study aimed to clarify the impact of low-dose LPS challenge on NASH pathological progression and to establish a novel murine NASH model. C57BL/6J mice were fed a choline-deficient l-amino-acid-defined (CDAA) diet to induce NASH, and low-dose LPS (0.5 mg/kg) was intraperitoneally injected thrice a week. CDAA-fed mice showed hepatic CD14 overexpression, and low-dose LPS challenge enhanced TLR4/NF-κB signaling activation in the liver of CDAA-fed mice. LPS challenge potentiated CDAA-diet-mediated insulin resistance, hepatic steatosis with upregulated lipogenic genes, and F4/80-positive macrophage infiltration with increased proinflammatory cytokines. It is noteworthy that LPS administration extensively boosted pericellular fibrosis with the activation of hepatic stellate cells in CDAA-fed mice. Exogenous LPS administration exacerbated pericellular fibrosis in CDAA-mediated steatohepatitis in mice. These findings suggest a key role for LPS/TLR4 signaling in NASH progression, and the authors therefore propose this as a suitable model to mimic human NASH.博士（医学）・甲第738号・令和2年3月16日© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)

L-カルニチンとアンギオテンシン-II1型受容体遮断薬の組み合わせは、非アルコール性脂肪肝炎ラットモデルにおける肝線維症に有益な効果を有する

Inflammation and oxidative stress contribute to the progression of nonalcoholic steatohepatitis (NASH). Hepatic fibrosis and activated hepatic stellate cells (Ac-HSCs) are attenuated by Angiotensin-II type 1 Receptor Blocker (ARB), and L-carnitine is effective for NASH by ameliorating oxidative stress, but neither agent is effective in a clinical setting. We evaluated the effect of the combination of L-carnitine and ARB on liver fibrosis using a rat NASH model. A Choline-Deficient/L-Amino Acid-defined (CDAA) diet was fed to F344 rats for 8 weeks. The rats were then divided into a control group, group receiving L-carnitine or ARB alone, and group receiving L-carnitine plus ARB. Therapeutic efficacy was assessed by evaluating liver fibrosis, liver fatty acid metabolism, and oxidative stress. ARB inhibited liver-specific tumor necrotic factor-α and LPS-binding protein, which are involved in hepatic inflammation. L-Carnitine reduced hepatic oxidative stress by rescuing hepatic sterol-regulatory elementbinding protein 1 and thiobarbituric acid reactive substances induced by the CDAA diet. Combination of L-carnitine and ARB improved liver fibrosis, with concomitant HSC suppression. Therefore, we suggest that L-carnitine and ARB are effective in suppressing liver fibrosis. Currently both drugs are in clinical use, and a combination of the two could be an effective therapy for NASH fibrosis.博士（医学）・甲第736号・令和2年3月16日Copyright © 2019 Hideto Kawaratani, Biomed J Sci & Tech Res. This is an openaccess article distributed under the terms of the Commons Attribution 4.0 License (https://creativecommons.org/licenses/by/4.0/)

肝線維化に対するファルネソイドX受容体アゴニストとジペプチジルペプチダーゼ-4阻害薬の併用効果

Aim: Non-alcoholic steatohepatitis (NASH) has a broad clinicopathological spectrum (inflammation to severe fibrosis). The farnesoid X receptor agonist obeticholic acid (OCA) ameliorates the histological features of NASH; satisfactory antifibrotic effects have not yet been reported. Here, we investigated the combined effects of OCA + a dipeptidyl peptidase-4 inhibitor (sitagliptin) on hepatic fibrogenesis in a rat model of NASH. Methods: Fifty Fischer 344 rats were fed a choline-deficient L-amino-acid-defined (CDAA) diet for 12 weeks. The in vitro and in vivo effects of OCA + sitagliptin were assessed along with hepatic fibrogenesis, lipopolysaccharide-Toll-like receptor 4 (TLR4) regulatory cascade and intestinal barrier function. Direct inhibitory effects of OCA + sitagliptin on activated hepatic stellate cells (Ac-HSCs) were assessed in vitro. Results: Treatment with OCA + sitagliptin potentially inhibited hepatic fibrogenesis along with Ac-HSC proliferation and hepatic transforming growth factor (TGF)-β1, α1(I)-procollagen, and tissue inhibitor of metalloproteinase-1 (TIMP-1) mRNA expression and hydroxyproline levels. Obeticholic acid inhibited hepatic TLR4 expression and increased hepatic matrix metalloproteinase-2 expression. Obeticholic acid decreased intestinal permeability by ameliorating CDAA diet-induced zonula occludens-1 disruption, whereas sitagliptin directly inhibited Ac-HSC proliferation. The in vitro suppressive effects of OCA + sitagliptin on TGF-β1 and α1(I)-procollagen mRNA expression and p38 phosphorylation in Ac-HSCs were almost consistent. Sitagliptin directly inhibited the regulation of Ac-HSC. Conclusions: Treatment with OCA + sitagliptin synergistically affected hepatic fibrogenesis by counteracting endotoxemia induced by intestinal barrier dysfunction and suppressing Ac-HSC proliferation. Thus, OCA + sitagliptin could be a promising therapeutic strategy for NASH.博士（医学）・甲第737号・令和2年3月16日© 2019 The Japan Society of HepatologyThis is the peer reviewed version of the following article: [https://onlinelibrary.wiley.com/doi/full/10.1111/hepr.13385], which has been published in final form at [https://doi.org/10.1111/hepr.13385]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions

ラット非アルコール性脂肪肝炎モデルに対するプロバイオティクスとアンギオテンシンⅡ受容体拮抗薬併用療法の肝線維化に対する有効性

Aim: Intestinal endotoxin is important for the progression of non-alcoholic steatohepatitis (NASH). Circulating endotoxin levels are elevated in most animal models of diet-induced non-alcoholic fatty liver disease (NAFLD) and NASH. Furthermore, plasma endotoxin levels are significantly higher in NAFLD patients, which is associated with small intestinal bacterial overgrowth and increased intestinal permeability. By improving the gut microbiota environment and restoring gut-barrier functions, probiotics are effective for NASH treatment in animal models. It is also widely known that hepatic fibrosis and suppression of activated hepatic stellate cells (Ac-HSCs) can be attenuated using an angiotensin-II type 1 receptor blocker (ARB). We thus evaluated the effect of combination probiotics and ARB treatment on liver fibrosis using a rat model of NASH. Methods: Fisher 344 rats were fed a choline-deficient/L-amino acid-defined (CDAA) diet for 8 weeks to generate the NASH model. Animals were divided into ARB, probiotics, and ARB plus probiotics groups. Therapeutic efficacy was assessed by evaluating liver fibrosis, the lipopolysaccharide Toll-like receptor (TLR)4 regulatory cascade, and intestinal barrier function. Results: Both probiotics and ARB inhibited liver fibrosis, with concomitant HSC activation and suppression of liver-specific transforming growth factor-β and TLR4 expression. Probiotics reduced intestinal permeability by rescuing zonula occludens-1 disruption induced by the CDAA diet. Angiotensin-II type 1 receptor blocker was found to directly suppress Ac-HSCs. Conclusions: Probiotics and ARB are effective in suppressing liver fibrosis through different mechanisms. Currently both drugs are in clinical use; therefore, the combination of probiotics and ARB is a promising new therapy for NASH.博士（医学）・乙第1465号・令和2年9月30日© 2018 The Japan Society of HepatologyThis is the pre-peer reviewed version of the following article: [https://onlinelibrary.wiley.com/doi/full/10.1111/hepr.13281], which has been published in final form at [https://doi.org/10.1111/hepr.13281]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions