Digestive Disease Research Center, Tehran University of Medical Sciences, Tehran, Iran.
Expert Rev Clin Immunol. 2013 May;9(5):409-22. doi: 10.1586/eci.13.27.
Inflammatory bowel disease (IBD) and colorectal cancer (CRC) are the major diseases of the lower gastrointestinal tract. The intestinal epithelium plays a critical role in the host's interactions with the large communities of resident luminal bacteria. Epithelial cells recognize the bacterial components via pattern-recognition receptors. Toll-like receptors (TLRs) are a major class of pattern-recognition receptors that are present on intestinal epithelial cells, including putative stem cells. Stem cells are responsible for tissue homeostasis and regeneration after injury including IBD. Stem cells are also implicated in the pathogenesis of CRC. In susceptible individuals, disruption of normal homeostatic balance between the host's mucosal cells and enteric microflora is believed to result in aberrant immune responses against the resident commensal bacteria, leading to IBD. Microbiological analyses have revealed that the composition and localization of microbiota is altered in CRC and IBD. It is plausible that stem cells directly sense and respond to microbiota. This review aims to summarize the current knowledge on the effect of microbiota and TLR signaling on intestinal stem cells. It also describes how TLR signaling could affect the stem cell regulatory pathways.
炎症性肠病（IBD）和结直肠癌（CRC）是下消化道的主要疾病。肠上皮在宿主与常驻腔细菌的大群落相互作用中起着关键作用。上皮细胞通过模式识别受体识别细菌成分。Toll 样受体（TLR）是存在于肠上皮细胞中的主要模式识别受体之一，包括假定的干细胞。干细胞负责组织稳态和损伤后的再生，包括 IBD。干细胞也与 CRC 的发病机制有关。在易感性个体中，宿主黏膜细胞和肠内微生物群之间正常的稳态平衡被破坏，被认为会导致针对常驻共生细菌的异常免疫反应，从而导致 IBD。微生物分析表明，CRC 和 IBD 中微生物群的组成和定位发生了改变。干细胞直接感知和响应微生物群是合理的。这篇综述旨在总结微生物群和 TLR 信号对肠道干细胞的影响的最新知识。它还描述了 TLR 信号如何影响干细胞调节途径。
