Boirivant Monica, Amendola Antonello, Butera Alessia, Sanchez Massimo, Xu Lili, Marinaro Mariarosaria, Kitani Atsushi, Di Giacinto Claudia, Strober Warren, Fuss Ivan J
Immune-Mediated Diseases Section, Department of Infectious, Parasitic, and Immune-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
Gastroenterology. 2008 Nov;135(5):1612-1623.e5. doi: 10.1053/j.gastro.2008.07.028. Epub 2008 Aug 5.
BACKGROUND & AIMS: Previous studies have indicated that a defective epithelial barrier leads to inflammation of the underlying lamina propria. Nevertheless, it is likely that physiologic breaks in the barrier must occur for homeostatic regulatory T cells to develop. We determined the effect of agents that disrupt epithelial tight junctions (ethanol and AT1002, a Vibrio cholerae zonula occludens toxin hexapeptide) on regulatory T-cell induction and resistance to induction of colitis by trinitrobenzene sulfonic acid (TNBS).
The effects of ethanol and AT1002 on colon immune function were evaluated by their capacity to induce direct phenotypic or functional changes in effector and regulatory cell populations and their indirect effect on the development of TNBS-induced colitis. The basis of regulatory cell development was evaluated with in vitro studies of isolated dendritic cell populations. The role of innate immunity was evaluated by in vivo gene silencing studies utilizing Toll-like receptor (TLR)-2-specific small interfering RNA (siRNA).
Both ethanol and AT1002 induced persistent latency-associated peptide-positive CD4(+) regulatory T cells that, as shown in adoptive transfer studies, render mice resistant to the induction of TNBS colitis. The development of these cells requires the presence of an intact microflora and the activity of CD11c(+) dendritic cells. Their induction is also influenced by innate immune factors operating through TLR-2, because attenuation of TLR-2 signaling by in vivo TLR-2 siRNA administration prevents their development.
A mild and/or transient breach in epithelial barrier function leads to dominant regulatory T-cell responses that protect the mucosa from inflammation.
既往研究表明，上皮屏障缺陷会导致其下方固有层发生炎症。然而，为使稳态调节性T细胞得以发育，屏障中的生理性破损可能是必需的。我们测定了破坏上皮紧密连接的试剂（乙醇和AT1002，一种霍乱弧菌小带闭合毒素六肽）对调节性T细胞诱导以及对三硝基苯磺酸（TNBS）诱导的结肠炎的诱导抗性的影响。
通过乙醇和AT1002诱导效应细胞和调节细胞群体直接表型或功能变化的能力及其对TNBS诱导的结肠炎发展的间接影响，来评估它们对结肠免疫功能的作用。通过对分离的树突状细胞群体进行体外研究，评估调节性细胞发育的基础。利用Toll样受体（TLR）-2特异性小干扰RNA（siRNA）进行体内基因沉默研究，评估天然免疫的作用。
乙醇和AT1002均诱导出持续的潜伏期相关肽阳性CD4(+)调节性T细胞，如过继转移研究所显示的，这些细胞使小鼠对TNBS结肠炎的诱导具有抗性。这些细胞的发育需要完整的微生物群的存在以及CD11c(+)树突状细胞的活性。它们的诱导也受通过TLR-2发挥作用的天然免疫因子的影响，因为体内给予TLR-2 siRNA减弱TLR-2信号会阻止它们的发育。
上皮屏障功能的轻度和/或短暂破损会导致占主导地位的调节性T细胞反应，从而保护黏膜免受炎症侵袭。
