Smith Jennifer M, Johanesen Priscilla A, Wendt Michael K, Binion David G, Dwinell Michael B
Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Rd,, Milwaukee, WI 53226, USA.
Am J Physiol Gastrointest Liver Physiol. 2005 Feb;288(2):G316-26. doi: 10.1152/ajpgi.00208.2004. Epub 2004 Sep 9.
Intestinal epithelial cell migration plays a key role in gastrointestinal mucosal barrier formation, enterocyte development, differentiation, turnover, wound healing, and adenocarcinoma metastasis. Chemokines, through engagement of their corresponding receptors, are potent mediators of directed cell migration and are critical in the establishment and regulation of innate and adaptive immune responses. The aim of this study was to define the role for the chemokine CXCL12 and its sole cognate receptor CXCR4 in regulating intestinal epithelial cell migration and to determine its impact on barrier integrity. CXCL12 stimulated the dose-dependent chemotactic migration of human T84 colonic epithelial cells. Epithelial cell migration was inhibited by CXCR4 neutralizing antibody, pertussis toxin, LY-294002, and PD-98059, thereby implicating Galpha(i), phosphatidylinositol 3-kinase (PI3-kinase), and the ERK1/2 MAP kinase pathways in CXCR4-specific signaling. CXCL12 was also shown to increase barrier integrity, as defined by transepithelial resistance and paracellular flux across differentiating T84 monolayers. To determine whether CXCL12 regulated epithelial restitution, we used the normal nontransformed intestinal epithelial cell-6 (IEC-6) wound healing model. By using RT-PCR, immunoblot analysis, and immunofluorescence microscopy, we first showed expression of both CXCR4 and its ligand by IEC-6 cells. We then demonstrated that CXCL12 activated comparable signaling mechanisms to stimulate epithelial migration in the absence of proliferation in wounded IEC-6 monolayers. Taken together, these data indicate that CXCL12 signaling via CXCR4 directs intestinal epithelial cell migration, barrier maturation, and restitution, consistent with an important mechanistic role for these molecules in mucosal barrier integrity and innate host defense.
肠上皮细胞迁移在胃肠道黏膜屏障形成、肠上皮细胞发育、分化、更新、伤口愈合及腺癌转移中起关键作用。趋化因子通过与其相应受体结合，是定向细胞迁移的有效介质，在固有免疫和适应性免疫应答的建立与调节中起关键作用。本研究的目的是确定趋化因子CXCL12及其唯一同源受体CXCR4在调节肠上皮细胞迁移中的作用，并确定其对屏障完整性的影响。CXCL12刺激人T84结肠上皮细胞的剂量依赖性趋化迁移。上皮细胞迁移受到CXCR4中和抗体、百日咳毒素、LY-294002和PD-98059的抑制，从而表明Gα(i)、磷脂酰肌醇3激酶（PI3激酶）和ERK1/2丝裂原活化蛋白激酶途径参与CXCR4特异性信号传导。CXCL12还显示可增加屏障完整性，这由跨分化T84单层的跨上皮电阻和细胞旁通量来定义。为了确定CXCL12是否调节上皮修复，我们使用了正常未转化的肠上皮细胞-6（IEC-6）伤口愈合模型。通过逆转录聚合酶链反应（RT-PCR）、免疫印迹分析和免疫荧光显微镜检查，我们首先显示IEC-6细胞表达CXCR4及其配体。然后我们证明CXCL12激活了类似的信号传导机制，以在受伤的IEC-6单层中无增殖的情况下刺激上皮迁移。综上所述，这些数据表明通过CXCR4的CXCL12信号传导指导肠上皮细胞迁移、屏障成熟和修复，这与这些分子在黏膜屏障完整性和固有宿主防御中的重要机制作用一致。
