Enhanced innate immune responsiveness and intolerance to intestinal endotoxins in human biliary epithelial cells contributes to chronic cholangitis
Enhanced innate immune responsiveness and intolerance to intestinal endotoxins in human biliary epithelial cells contributes to chronic cholangitis
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DOI：
10.1111/j.1478-3231.2011.02635.x
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发表时间：
2011-11-01
影响因子：
6.7
通讯作者：
Podolsky, Daniel K.
中科院分区：
文献类型：
--
作者：
Mueller, Tobias;Beutler, Claudia;Podolsky, Daniel K.
背景：模式识别受体（PRRs）参与人胆管上皮细胞（BEC）的先天性免疫防御。PRR信号传导的严格控制提供了对人胆汁中生理量的肠内毒素的耐受性，以避免BEC中恒定的先天免疫激活。目的：我们想确定对肠内毒素的不适当的先天免疫反应是否有助于慢性胆道炎症的发展和持续。研究方法：我们研究了原发性硬化性胆管炎（PSC），酒精性肝病和非慢性肝病患者分离的原发性BEC中PRR介导的先天免疫反应和保护性内毒素耐受性。表达研究包括北方印迹、RT-PCR、Western印迹和免疫细胞化学。功能研究包括免疫沉淀蛋白质印迹法、内毒素摄取的FACS、NF-κ B活化试验和分泌型IL-8和肿瘤坏死因子（TNF）-α的ELISA。结果如下：来自移植PSC肝脏的原代BEC显示TLR和NOD蛋白表达可逆性增加，并且MyD88/IRAK信号传导复合物活化。因此，PSC BEC对内毒素表现出不适当的先天免疫应答，并且在重复内毒素暴露后没有产生免疫耐受。这种内毒素高反应性可能是因为PSC肝脏中大量表达的IFN-γ和TNF-α的刺激作用，其刺激BEC中TLR 4介导的内毒素信号传导，导致TLR 4介导的内毒素掺入增加和TLR 4信号传导级联的失活受损。由于TNF-α抑制部分恢复了保护性先天免疫耐受，内源性TNF-α分泌可能导致BEC中不适当的内毒素反应。结论：由于BEC中PRR信号增强，对肠内毒素的不适当的先天免疫应答和随后的内毒素不耐受可能导致慢性胆管炎。
Background: Pattern recognition receptors (PRRs) orchestrate the innate immune defence in human biliary epithelial cells (BECs). Tight control of PRR signalling provides tolerance to physiological amounts of intestinal endotoxins in human bile to avoid constant innate immune activation in BECs. Aims: We wanted to determine whether inappropriate innate immune responses to intestinal endotoxins contribute to the development and perpetuation of chronic biliary inflammation. Methods: We examined PRR-mediated innate immune responses and protective endotoxin tolerance in primary BECs isolated from patients with primary sclerosing cholangitis (PSC), alcoholic liver disease and patients without chronic liver disease. Expression studies comprised northern blots, RT-PCR, Western blots and immunocytochemistry. Functional studies comprised immuno-precipitation Western blots, FACS for endotoxin uptake, and NF-kappa B activation assays and ELISA for secreted IL-8 and tumour necrosis factor (TNF)-alpha. Results: Primary BECs from explanted PSC livers showed reversibly increased TLR and NOD protein expression and activation of the MyD88/IRAK signalling complex. Consecutively, PSC BECs exhibited inappropriate innate immune responses to endotoxins and did not develop immune tolerance after repeated endotoxin exposures. This endotoxin hyper-responsiveness was probably because of the stimulatory effect of abundantly expressed IFN-gamma and TNF-alpha in PSC livers, which stimulated TLR4-mediated endotoxin signalling in BECs, leading to increased TLR4-mediated endotoxin incorporation and impaired inactivation of the TLR4 signalling cascade. As TNF-alpha inhibition partly restored protective innate immune tolerance, endogenous TNF-alpha secretion probably contributed to inappropriate endotoxin responses in BECs. Conclusion: Inappropriate innate immune responses to intestinal endotoxins and subsequent endotoxin intolerance because of enhanced PRR signalling in BECs probably contribute to chronic cholangitis.