Goto Yoshiyuki, Kurashima Yosuke, Kiyono Hiroshi
Division of Molecular Immunology, Medical Mycology Research Center, Chiba University.
Rinsho Ketsueki. 2015 Oct;56(10):2205-12. doi: 10.11406/rinketsu.56.2205.
The intestine is a unique organ which is continuously exposed to various antigens such as food-derived antigens, as well as both commensal and pathogenic bacteria, under physiological conditions. Intestinal epithelial cells constitute both a physical and an immunological barrier system against this vast array of antigens. The α1,2-fucose-conjugated carbohydrate chains expressed on intestinal epithelial cells are physiologically and immunologically important and are regulated by type III innate lymphoid cells (ILC3). IL-22-producing ILC3 induce anti-microbial molecules such as RegIIIγ, contributing to the formation of a safeguard system for homeostasis of commensal flora in the intestinal lumen, containment of Alcaligenes in Peyer's patches, and establishment of a defensive platform against infection by pathogenic bacteria. The other intestinal innate immune cell type, the mast cell, is also a critical player. Mast cells are activated by ATP produced in host cells and commensal flora, predisposing to the development of inflammatory bowel diseases. Furthermore, mucosal mast cells regulate the differentiation of follicular helper T cells through ATP signals and contribute to subsequent IgA affinity maturation and regulating the homeostasis of commensal microflora.
肠道是一个独特的器官，在生理条件下，它持续暴露于各种抗原，如食物来源的抗原以及共生菌和病原菌。肠上皮细胞构成了针对这大量抗原的物理和免疫屏障系统。肠上皮细胞上表达的α1,2-岩藻糖共轭碳水化合物链在生理和免疫方面都很重要，并受III型固有淋巴细胞（ILC3）调节。产生IL-22的ILC3诱导抗菌分子如RegIIIγ的产生，有助于形成一个保障系统，以维持肠腔内共生菌群的稳态，控制派尔集合淋巴结中的产碱杆菌，并建立一个抵御病原菌感染的防御平台。另一种肠道固有免疫细胞类型，即肥大细胞，也是一个关键角色。肥大细胞被宿主细胞和共生菌群产生的ATP激活，易引发炎症性肠病。此外，黏膜肥大细胞通过ATP信号调节滤泡辅助性T细胞的分化，并有助于随后的IgA亲和力成熟以及调节共生微生物群的稳态。
