肠上皮内淋巴细胞对肠上皮屏障功能的影响

目的：研究在痢疾志贺菌F2a-12脂多糖刺激下，大鼠小肠上皮内淋巴细胞（IEL）对人结肠癌上皮细胞系Caco-2屏障功能的影响。方法：新鲜分离的大鼠小肠IEL与Caco-2共培养，并用F2a-12LPS刺激共培养细胞。通过检测短路电流、紧密连接相关蛋白表达及透射电镜来反映上皮屏障功能的变化。结果：共培养后跨上皮电阻增加，但在LPS刺激后显著降低；紧密连接相关蛋白ZO-2mRNA表达在共培养后增加，LPS刺激后共培养细胞ZO-1mRNA表达显著下降；透射电镜下可见共培养后细胞间紧密连接显著增强，但在LPS刺激后共培养细胞间的连接几乎消失。首次在电镜下发现上皮细胞与IEL间有连接样结构的存在，为其相互作用提供了形态学的证据。结论：IEL对上皮屏障功能具双向调节作用，在生理状态下增强，但在感染信号存在时降低。

Modulation of enteric epithelial barrier function by intestinal intraepithelial lymphocytes

Objective: To examine modulation of epithelial b arrier function of human colonic epithelial cell line Caco-2 by intestinal intr aepithelial lymphocyte (IEL) in response to challenge of Shigella F2a-12 LP S. Methods: Freshly isolated rat IEL were co-cultured with Ca co-2, then exposed to Shigella F2a-12 LPS. Barrier function of the epithel ial monolayer was measured by the short-circuit current technique (I_(sc)) a nd examined by transmission electron microscopy (TEM) and mRNA expression of tig ht junction associated proteins ZO-1 and ZO-2. Results: The transepithelial resistance of the epithelial monolayers increased when co-cultu red with IEL,while decreased significantly after exposed to Shigella F2a-12 LPS. mRNA expression of tight junction associated protein ZO-2 increased after co-culture, while mRNA expression of ZO-1 decreased after co-cultured and ch allenged by LPS. Tight junction was enhanced significantly after co-culture und er TEM, while almost disappeared when challenged by LPS. Junction-like structur e was also found between IEL and Caco-2 under TEM for the first time, providing the first structure evidence for their interaction. Conclusion: The results suggest that IEL influence epithelial barrier function in two way s: enhancing the barrier function under physiological condition and reducing whi le under the challenge of infectious signals.