Monteleone Giovanni, Monteleone Ivan, Fina Daniele, Vavassori Piero, Del Vecchio Blanco Giovanna, Caruso Roberta, Tersigni Roberto, Alessandroni Luciano, Biancone Livia, Naccari Gian Carlo, MacDonald Thomas T, Pallone Francesco
Dipartimento di Medicina Interna e Centro di Eccellenza per lo studio delle malattie complesse e multifattoriali, Università Tor Vergata, Rome, Italy.
Gastroenterology. 2005 Mar;128(3):687-94. doi: 10.1053/j.gastro.2004.12.042.
BACKGROUND & AIMS: T-helper (Th)1 cells play a central role in the pathogenesis of tissue damage in Crohn's disease (CD). Interleukin (IL)-12/STAT4 signaling promotes Th1 cell commitment in CD, but other cytokines are needed to maintain activated Th1 cells in the mucosa. In this study, we examined the expression and role of IL-21, a T-cell-derived cytokine of the IL-2 family; in tissues and cells isolated from patients with inflammatory bowel disease.
IL-21 was examined by Western blotting in whole mucosa and lamina propria mononuclear cells (LPMCs) from patients with CD, ulcerative colitis (UC), and controls. We also examined the effects of exogenous IL-12 on IL-21 production, as well as the effects of blocking IL-21 with an IL-21-receptor Ig fusion protein. Interferon (IFN)-gamma was measured in the culture supernatants by enzyme-linked immunosorbent assay, and phosphorylated STAT4 and T-bet were examined by Western blotting.
IL-21 was detected in all samples, but its expression was higher at the site of disease in CD in comparison with UC and controls. Enhanced IL-21 was seen in both ileal and colonic CD and in fibrostenosing and nonfibrostenosing disease. IL-12 enhanced IL-21 in normal lamina propria lymphocytes through an IFN-gamma-independent mechanism, and blocking IL-12 in CD LPMCs decreased anti-CD3-stimulated IL-21 expression. Neutralization of IL-21 in CD LPMC cultures decreased phosphorylated STAT4 and T-bet expression, thereby inhibiting IFN-gamma production.
Our data suggest that IL-21 contributes to the ongoing Th1 mucosal response in CD.
辅助性T（Th）1细胞在克罗恩病（CD）组织损伤的发病机制中起核心作用。白细胞介素（IL）-12/信号转导子和转录激活子4（STAT4）信号通路促进CD中Th1细胞的分化，但还需要其他细胞因子来维持黏膜中活化的Th1细胞。在本研究中，我们检测了IL-21（IL-2家族中一种T细胞源性细胞因子）在炎症性肠病患者分离的组织和细胞中的表达及作用。
采用蛋白质免疫印迹法检测CD、溃疡性结肠炎（UC）患者及对照者全黏膜和固有层单个核细胞（LPMC）中IL-21的表达。我们还检测了外源性IL-12对IL-21产生的影响，以及用IL-21受体Ig融合蛋白阻断IL-21的作用。采用酶联免疫吸附测定法检测培养上清液中干扰素（IFN）-γ水平，并用蛋白质免疫印迹法检测磷酸化STAT4和T-bet的表达。
在所有样本中均检测到IL-21，但与UC和对照相比，其在CD病变部位的表达更高。在回肠和结肠CD以及纤维狭窄型和非纤维狭窄型疾病中均观察到IL-21表达增强。IL-12通过不依赖IFN-γ的机制增强正常固有层淋巴细胞中IL-21的表达，而阻断CD患者LPMC中的IL-12可降低抗CD3刺激的IL-21表达。中和CD患者LPMC培养物中的IL-21可降低磷酸化STAT4和T-bet的表达，从而抑制IFN-γ的产生。
我们的数据表明，IL-21促成了CD中持续存在的Th1黏膜反应。
