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Okamura, Atsushi ; Harada, Kenichi ; Nio, Masaki ; Nakanuma, Yasuni
概要:
Biliary atresia (BA) is thought to be associated with infections by viruses such as Reoviridae and is characterized hist
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ologically by fibrosclerosing cholangitis with proinflammatory cytokine-mediated inflammation. Interleukin (IL)-32 affects the continuous inflammation by increasing the production of proinflammatory cytokines. In this study, the role of IL-32 in the cholangitis of BA was examined. Immunohistochemistry for IL-32 and caspase 1 was performed using 21 samples of extrahepatic bile ducts resected from BA patients. Moreover, using cultured human biliary epithelial cells (BECs), the expression of IL-32 and its induction on stimulation with a Toll-like receptor [(TLR)-3 ligand (poly(I:C)] and proinflammatory cytokines was examined. BECs composing extrahepatic bile ducts showing cholangitis expressed IL-32 in BA, but not in controls. Caspase 1 was expressed constantly on BECs of both BA and control subjects. Furthermore, poly(I:C) and proinflammatory cytokines [(IL-1β, interferon (IFN)-γ and tumour necrosis factor (TNF)-α] induced IL-32 expression strongly in cultured BECs, accompanying the constant expression of TLR-3 and caspase 1. Our results imply that the expression of IL-32 in BECs was found in the damaged bile ducts of BA and induced by biliary innate immunity via TLR-3 and proinflammatory cytokines. These findings suggest that IL-32 is involved initially in the pathogenic mechanisms of cholangitis in BA and also plays an important role in the amplification and continuance of periductal inflammatory reactions. It is therefore tempting to speculate that inhibitors of IL-32 could be useful for attenuating cholangitis in BA. © 2013 British Society for Immunology.
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| 2.
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論文
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原田, 憲一 ; Harada, Kenichi
概要:
原発性胆汁性肝硬変(PBC)は胆管細胞アポトーシスによる胆管消失を特徴とする自己免疫疾患で、病因として細菌感染症の関与が想定されている。我々はヒト培養胆管細胞を樹立し、アポトーシスの分子基盤および自然免疫の関与について解析した。その結果、胆
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管細胞はToll様受容体(TLR)のうち、少なくともTLR1〜TLR6を有していた。また、主要な細菌性のpathogen-associated molecularpatterns(PAMPs)であるリポポリサッカライド(LPS)刺激では有意な細胞死は誘導されなかったが、蛋白合成抑制状熊の胆管細胞では細菌性PAMPsが直接アポトーシスを誘導しうることが示された。さらに細菌性PAMPsに対する抗アポトーシス効果の一つとしてNF一κB依存性のHIAP-1発現亢進が重要であることが示唆された。一方、ウイルス関連のPAMPs(合成2本鎖RNA(Poly I:C))刺激では、転写因子であるNF-κBやinterferon regulatory factor-3(IRF-3)の活性化と共に、アポトーシス誘導分子であるTRAILの発現亢進と胆管細胞アポトーシス誘導が見られた。さらに、TLR4などを介した細菌性PAMPsに対する自然免疫応答は、持続的な刺激にてトレランスが誘導されたが、Poly I:Cに対するトレランスは誘導されず、2本鎖RNAが存在する限り自然免疫応答が持続した。以上の結果より、胆管細胞は自然免疫応答にてアポトーシスによる自らの細胞死を誘導することができ、微生物(特に2本鎖RNAウイルス)の関与が想定されている胆管消失疾患の病態形成に直接関与していることが示唆された。<br />Biliary epithelial cells possess the essential components of the innate immune system consisting of Toll-like receptors (TLRs) which recognize pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS). LPS is known to cause cell injury including apoptosis. We established human intrahepatic biliary epithelial cells (HIBECs) and examined the PAMPs-induced apoptosis in HIBECs. The distinct induction of apoptosis was not found by the treatment with any bacterial PAMPs, but in the condition of an inhibition of NF-KB-dependent protein synthesis, HIBECs undergo apoptosis by PAMPs in the manner of caspase-dependence. In contrast, stimulation with polyinosinic-polycytidylic acid (poly(I:C), a synthetic analog of viral dsRNA) induced the activation of transcription factors (NF-KB and interferon regulatory factor 3) and the production of interferon-β1 (IFN-β1) as potent antiviral responses in HIBECs. Moreover, poly(I:C) up-regulated the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and both poly(I:C) and TRAIL reduced the viability of cultured human HIBECs by enhancing apoptosis. In conclusion, bacterial and viral PAMPs could induce the apoptosis in human biliary epithelial cells as a result of the biliary innate immune response, supporting the notion that biliary innate immunity is directly associated with the pathogenesis of cholangiopathies in biliary diseases such as primary biliary cirrhosis.<br />研究課題/領域番号:18590326, 研究期間(年度):2006–2007<br />出典：「原発性胆汁性肝硬変の胆管細胞アポトーシスにおける自然免疫の関与」研究成果報告書 課題番号18590326 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）) 本文データは著者版報告書より作成
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