Down-regulation of single immunoglobulin interleukin-1R-related molecule (SIGIRR)/TIR8 expression in intestinal epithelial cells during inflammation
Down-regulation of single immunoglobulin interleukin-1R-related molecule (SIGIRR)/TIR8 expression in intestinal epithelial cells during inflammation
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DOI：
10.1111/j.1365-2249.2010.04254.x
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发表时间：
2010-11-01
影响因子：
4.6
通讯作者：
Kinoshita, Y.
中科院分区：
文献类型：
--
作者：
Kadota, C.;Ishihara, S.;Kinoshita, Y.
单个免疫球蛋白（IG）白细胞介素-1受体相关分子（SIGIRR）是一种免疫球蛋白样膜蛋白，对Toll样受体（TLR）-4介导的信号传导负调控至关重要。我们研究了炎症过程中肠上皮细胞（IEC）中SIGIRR的表达及其调节机制。采用实时荧光定量PCR和免疫组化方法检测溃疡性结肠炎（UC）患者活动期和非活动期结肠黏膜中SIGIRR的表达。采用三硝基苯磺酸（TNBS）和右旋糖酐硫酸钠（DSS）建立小鼠实验性结肠炎模型，采用实时荧光定量PCR、免疫组化和流式细胞术检测结肠上皮SIGIRR的表达。使用培养的IEC在体外评估脂多糖（LPS）和肿瘤坏死因子（TNF）-α对SIGIRR表达的影响。为了阐明在IEC中SIGIRR的表达调控，使用凝胶移位和染色质免疫沉淀（ChIP）测定来检查转录因子SP1在SIGIRR启动子的响应元件处的结合能力。在人类结肠样品中，SIGIRR主要在IEC中表达，与活性粘膜相比，其水平在非活性中显著更高。在小鼠中，结肠炎发展后SIGIRR结肠表达迅速下降，并逐渐恢复到基础水平。实验性结肠炎介导的IEC中SIGIRR的下调也通过IH和流式细胞术结果证实。此外，由TLR配体和TNF-α诱导的炎性病症导致IEC中SIGIRR表达的显著下调，这依赖于SIGIRR启动子的响应元件处的SP1结合的降低。我们发现SIGIRR在IEC中表达，并作为维持肠道先天免疫的负调节因子，其在炎症过程中通过抑制SP1介导的通路而下调。
P>Single immunoglobulin (Ig) interleukin-1R-related molecule (SIGIRR) is an Ig-like membrane protein critical for negative regulation of Toll-like receptor (TLR)-4-mediated signalling. We investigated SIGIRR expression and its regulation mechanism in intestinal epithelial cells (IECs) during inflammation. Endoscopic biopsy specimens were obtained from active and inactive colonic mucosa of ulcerative colitis (UC) patients, then SIGIRR expression was examined using real-time polymerase chain reaction (PCR) and immunohistochemistry (IH). Mice experimental colitis models were established by administrations of sulphonic acid (TNBS) and dextran sodium sulphate (DSS), and epithelial expression of SIGIRR was examined using real-time PCR, IH and flow cytometry. The effects of lipopolysaccharide (LPS) and tumour necrosis factor (TNF)-alpha on SIGIRR expression were evaluated in vitro using cultured IECs. To elucidate SIGIRR expression regulation in IECs, binding ability of the transcription factor SP1 at the responsive element of the SIGIRR promoter was examined using gel-shift and chromatin immunoprecipitation (ChIP) assays. In human colonic samples, SIGIRR was expressed mainly in IECs at levels significantly higher in inactive compared to active mucosa. In the mice, SIGIRR colonic expression decreased rapidly after colitis development and returned gradually to basal levels. Experimental colitis-mediated down-regulation of SIGIRR in IECs was also confirmed by IH and flow cytometry results. Further, inflammatory conditions induced by TLR ligands and TNF-alpha caused significant down-regulation of SIGIRR expression in IECs, which was dependent upon decreased SP1 binding at the responsive element of the SIGIRR promoter. We found that SIGIRR is expressed in IECs and serves as a negative regulator to maintain gut innate immunity, which is down-regulated during inflammation by inhibition of an SP1-mediated pathway.