淋巴毒素α1/β2及其受体在溃疡性结肠炎肠道黏膜免疫中的作用及意义

Role and significance of lymphotoxin α1/β2 and its receptor LTβR in intestinal mucosal immunity of ulcerative colitis

目的 :探讨淋巴毒素α1/β2(lymphotoxinα1/β2,LTα1/β2)、淋巴毒素β受体(lymphotoxinβreceptor,LTβR)及相关信号通路在溃疡性结肠炎肠道黏膜免疫中的作用。方法 :研究纳入20名正常对照者及40例活动期溃疡性结肠炎患者,所有入组者均于内镜下取活检标本进行研究。采用实时PCR法、蛋白印迹法、免疫组织化学及免疫荧光法,检测研究对象肠道黏膜的生物功能学指标及LTα1/β2、LTβR和NF-κB途径相关蛋白激酶磷酸化的表达水平。结果:溃疡性结肠炎患者的结肠黏膜中LTα1/β2、LTβR的免疫组织化学检测结果表达水平较正常对照者明显增多(LTα1/β2为39.84±5.24比5.34±1.36;LTβR为40.95±11.37比4.31±3.25;P<0.01);m RNA表达水平明显高于正常对照者(LTα1/β2为1.58±0.98比0.39±0.32;LTβR为3.12±2.22比1.34±0.58;P<0.01);溃疡性结肠炎组结肠黏膜中LTα1/β2、LTβR的蛋白表达水平明显高于正常对照者(LTα1/β2:3.67±1.22比1.02±0.78;LTβR为3.45±1.74比1.89±0.69;P<0.01)。溃疡性结肠炎患者LTα1/β2、LTβR的m RNA表达水平与其疾病严重程度Geboes评分呈正相关;溃疡性结肠炎结肠黏膜组织中膜受体LTβR表达于树突细胞表面;溃疡性结肠炎患者结肠黏膜中Iκκβ、IκBα和NF-κBp65蛋白磷酸化较正常对照者明显增加(P<0.01)。结论:淋巴细胞表达的LTα1/β2,可能通过结合于树突细胞表面的LTβR并激活NF-κB炎症通路,从而在溃疡性结肠炎患者的肠道黏膜免疫中发挥重要作用。

Objective： To investigate the role of lymphotoxin α1/β2, LTβR and its signaling pathway in intestinal mucosal immunity of ulcerative colitis（UC）. Methods： Forty patients who had active ulcerative colitis confirmed by biopsy and 40 normal controls had their biopsy specimens collected during colonoscopy. The expressions of lymphotoxin α1/β2,LTβR and NF-κB pathway associated protein kinase phosphorylation in UC patients and controls were detected by immunohistochemistry, real-time PCR, Western blotting and immunofluorescence assay. Results： Immunohistochemistry showed that the expressions of LTα1/β2 and LTβR in ulcerative colitis patients were higher than that in normal controls（39.84±5.24 vs 5.34±1.36, P〈0.01; 40.95±11.37 vs 4.31±3.25, P〈0.01）. The m RNA expression level of LTα1/β2 was higher in ulcerative colitis when compared with the normal controls（1.58 ±0.98 vs 0.39±0.32, P〈0.01）; as well as the LTβR（3.12±2.22 vs 1.34±0.58, P〈0.01）. The protein expression level of LTβR was also higher in ulcerative colitis when compared with normal controls（3.67±1.22 vs 1.02±0.78, P〈0.01）; as well as the LTβR（3.45±1.74 vs 1.89±0.69, P〈0.01）. In UC patients, the m RNA expression levels of LTα1/β2 and LTβR were positively correlated with the severity of inflammatory bowel disease. The surface markers of dendritic cell were partially merged with the LTβR marker. Phosphorylation of Iκκβ, IκBα and the activation of NF-κBp65 were enhanced in ulcerative colitis. Conclusions： LTα1/β2 expressed on lymphocytes may activate NF-κB signaling pathway by binding with LTβR on dendritic cells,thus plays an important role in intestinal mucosal immunity of ulcerative colitis.