Ikeda Hiroko, Sasaki Motoko, Ishikawa Akira, Sato Yasunori, Harada Kenichi, Zen Yoh, Kazumori Hideaki, Nakanuma Yasuni
Department of Human Pathology, Kanazawa University Graduate School of Medicine, Kanazawa, Japan.
Lab Invest. 2007 Jun;87(6):559-71. doi: 10.1038/labinvest.3700556. Epub 2007 Apr 9.
The mechanism of transformation of biliary epithelium leading to intestinal metaplasia, which is significantly involved in biliary diseases, remains unclear. CDX2, an intestine-specific transcription factor, is thought to regulate intestinal mucin MUC2 (mucus core protein) expression. We took advantage of polycystic kidney (PCK) rats as a model of chronic suppurative cholangitis with intestinal metaplasia and of cultured biliary epithelial cells (BECs) from PCK rats to clarify the causal relation between bacterial components such as pathogen-associated molecular patterns (PAMPs) and the development of intestinal metaplasia of bile ducts. Histological, immunohistochemical, and in situ hybridization studies were conducted in PCK rat livers. In cultured BECs, CDX2 and MUC2 were expressed following treatment with PAMPs and inhibitors (anti-Toll-like receptor (TLR)2/TLR4 antibody, nuclear factor-kappaB (NF-kappaB) inhibitor MG132). Chronic suppurative cholangitis with intestinal metaplasia developed as the PCK rats aged, and intestinal metaplasia and aberrant CDX2 and MUC2 expression developed in parallel. Intraluminal bacteria and the expression of TLR2 and TLR4 in BECs were demonstrated in the bile ducts, showing chronic suppurative cholangitis. In cultured BECs, treatment with PAMPs induced upregulation of CDX2 and MUC2 expression, and this effect was abolished by pretreatment with anti-TLR2 and anti-TLR4 antibody and MG132. A knockdown of CDX2 by CDX2 small interfering RNA inhibited MUC2 expression in cultured BECs induced by PAMPs, and transfection of CDX2 expression vector induced MUC2 expression. In conclusion, bacterial components may induce upregulation of the CDX2 expression followed by MUC2 expression via TLR and the NF-kappaB system in cultured BECs, and could be related to the development of intestinal metaplasia of the bile ducts.
胆管上皮转化为肠化生的机制仍不清楚，而肠化生在胆管疾病中起着重要作用。CDX2是一种肠道特异性转录因子，被认为可调节肠道黏蛋白MUC2（黏液核心蛋白）的表达。我们利用多囊肾（PCK）大鼠作为慢性化脓性胆管炎伴肠化生的模型，并使用来自PCK大鼠的培养胆管上皮细胞（BECs），以阐明病原体相关分子模式（PAMPs）等细菌成分与胆管肠化生发展之间的因果关系。对PCK大鼠肝脏进行了组织学、免疫组织化学和原位杂交研究。在培养的BECs中，用PAMPs和抑制剂（抗Toll样受体（TLR）2/TLR4抗体、核因子-κB（NF-κB）抑制剂MG132）处理后，CDX2和MUC2表达。随着PCK大鼠年龄的增长，出现了伴有肠化生的慢性化脓性胆管炎，肠化生以及异常的CDX2和MUC2表达同时出现。在胆管中证实了管腔内细菌以及BECs中TLR2和TLR4的表达，显示为慢性化脓性胆管炎。在培养的BECs中，用PAMPs处理可诱导CDX2和MUC2表达上调，而用抗TLR2和抗TLR4抗体以及MG132预处理可消除这种作用。用CDX2小干扰RNA敲低CDX2可抑制培养的BECs中由PAMPs诱导的MUC2表达，而转染CDX2表达载体可诱导MUC2表达。总之，细菌成分可能通过TLR和NF-κB系统在培养的BECs中诱导CDX2表达上调，随后诱导MUC2表达，并且可能与胆管肠化生的发展有关。
