Blanchard Carine, Durual Stéphane, Estienne Monique, Emami Shahin, Vasseur Sophie, Cuber Jean-Claude
INSERM U45, Faculté de Médecine Laennec, 69372 Lyon Cedex 08, France.
Int J Biochem Cell Biol. 2005 Dec;37(12):2559-73. doi: 10.1016/j.biocel.2005.06.010. Epub 2005 Jul 21.
Several inflammatory processes of the bowel are characterized by an accumulation of eosinophils at sites of inflammation. The mechanisms that govern mucosal infiltration with eosinophils are not fully understood. Eotaxin-3/CCL-26 belongs to a family of CC chemokines, which are potent chemoattractants for eosinophils. In this study, we hypothesized that intestinal epithelial cells could release eotaxin-3. We demonstrate that the T helper 2 type cytokines interleukin-4 or interleukin-13 increase eotaxin-3 mRNA levels and eotaxin-3 protein expression in the human intestinal epithelial cell lines HT-29 CL.19A and T84 in a dose-dependent manner. Addition of actinomycin-D prior to interleukin-4/-13 stimulation led to decreases in eotaxin-3 mRNA levels similar to those observed in controls without interleukin-4/-13. Interleukin-4 and interleukin-13 activated signal transducer and activator of transcription 6 which was found to bind the two canonical signal transducer and activator of transcription 6 binding sites located in the eotaxin-3 promoter. Experiments with the eotaxin-3 promoter luciferase constructs revealed that the most proximal signal transducer and activator of transcription 6 binding site located between positions -62 and -71 relative to the transcriptional start was necessary for full eotaxin-3 promoter activity. Importantly, we present evidence that the signal transducer and activator of transcription 6 is necessary and sufficient for interleukin-4 or interleukin-13 mediated eotaxin-3 gene up-regulation using HT-29 CL.19A cells expressing a dominant-negative signal transducer and activator of transcription 6. Overall, these results demonstrate that epithelial eotaxin-3 is up-regulated in the context of a T helper 2 mediated inflammatory bowel disease via the signal transducer and activator of transcription 6, thus suggesting that the intestinal epithelium actively participates in the recruitment of eosinophils at the site of inflammation.
几种肠道炎症过程的特征是嗜酸性粒细胞在炎症部位积聚。嗜酸性粒细胞向黏膜浸润的机制尚未完全明确。嗜酸性粒细胞趋化因子-3/CCL-26属于CC趋化因子家族，是嗜酸性粒细胞的有效化学引诱剂。在本研究中，我们推测肠道上皮细胞能够释放嗜酸性粒细胞趋化因子-3。我们证明，辅助性T细胞2型细胞因子白细胞介素-4或白细胞介素-13可使人类肠道上皮细胞系HT-29 CL.19A和T84中的嗜酸性粒细胞趋化因子-3信使核糖核酸水平和嗜酸性粒细胞趋化因子-3蛋白表达呈剂量依赖性增加。在白细胞介素-4/-13刺激之前添加放线菌素-D导致嗜酸性粒细胞趋化因子-3信使核糖核酸水平下降，与未接受白细胞介素-4/-13刺激的对照组中观察到的情况相似。白细胞介素-4和白细胞介素-13激活了信号转导及转录激活因子6，发现其与位于嗜酸性粒细胞趋化因子-3启动子中的两个典型信号转导及转录激活因子6结合位点相结合。对嗜酸性粒细胞趋化因子-3启动子荧光素酶构建体进行的实验表明，相对于转录起始位点，位于-62至-71位之间的最靠近近端的信号转导及转录激活因子6结合位点对于嗜酸性粒细胞趋化因子-3启动子的完全活性是必需的。重要的是，我们提供证据表明，使用表达显性负性信号转导及转录激活因子6的HT-29 CL.19A细胞，信号转导及转录激活因子6对于白细胞介素-4或白细胞介素-13介导的嗜酸性粒细胞趋化因子-3基因上调是必需且充分的。总体而言，这些结果表明，在辅助性T细胞2介导的炎症性肠病背景下，上皮细胞嗜酸性粒细胞趋化因子-3通过信号转导及转录激活因子6上调，因此提示肠道上皮细胞在炎症部位积极参与嗜酸性粒细胞的募集。
