Fréour Thomas, Jarry Anne, Bach-Ngohou Kalyane, Dejoie Thomas, Bou-Hanna Chantal, Denis Marc G, Mosnier Jean-François, Laboisse Christian L, Masson Damien
INSERM U539, Faculté de Médecine, F-44035 Nantes, France.
Int J Mol Med. 2009 Jan;23(1):41-8.
Inflammatory bowel diseases (IBD) are characterized by tumor necrosis factor alpha (TNF-alpha)-mediated epithelial barrier disruption. TNF-alpha production and the bioavailability of its receptors on the cell surface are regulated by TACE (TNF-alpha converting enzyme), a pleiotropic metalloprotease also known as ADAM17, and its specific inhibitor TIMP3. We therefore examined ADAM17 and TIMP3 expression in human intestinal epithelial cells (IEC) using immunohistochemistry on tissue microarrays and real-time PCR on preparations of IEC isolated from human normal and IBD colon. The effects of TACE inhibition by TIMP3 or a pharmacological inhibitor were assessed in inflammatory conditions on a TIMP3-deficient colonic cell line HT29-Cl.16E. Both TACE and TIMP3 were found to be constitutively expressed by intestinal epithelial cells in the normal and inflammatory human intestinal barrier. In the TIMP3-deficient cell line, the addition of recombinant human TIMP3 or of Tapi-2, a pharmacological ADAM17 inhibitor, i) sensitized the cells to TNF-alpha-mediated hyperpermeability, ii) down-regulated tight junction-associated protein expression and iii) inhibited TNFRI shedding. In conclusion, our data showed that TACE and TIMP3 were co-expressed in the human intestinal barrier and that TACE inhibition, either physiologically or pharmacologically, amplified TNF-alpha-mediated hyperpermeability. TIMP3 could thus play a major role in inflammatory conditions by creating an autocrine effect leading to amplified epithelial barrier hyperpermeability.
炎症性肠病（IBD）的特征是肿瘤坏死因子α（TNF-α）介导的上皮屏障破坏。TNF-α的产生及其在细胞表面受体的生物利用度受TACE（TNF-α转换酶，一种多效性金属蛋白酶，也称为ADAM17）及其特异性抑制剂TIMP3的调节。因此，我们使用组织微阵列上的免疫组织化学以及从人正常和IBD结肠分离的IEC制剂上的实时PCR，检测了人肠上皮细胞（IEC）中ADAM17和TIMP3的表达。在炎症条件下，在TIMP3缺陷的结肠细胞系HT29-Cl.16E中评估了TIMP3或药理抑制剂对TACE的抑制作用。在正常和炎症性人肠屏障中，发现TACE和TIMP3均由肠上皮细胞组成性表达。在TIMP3缺陷细胞系中，添加重组人TIMP3或药理ADAM17抑制剂Tapi-2，i）使细胞对TNF-α介导的高通透性敏感，ii）下调紧密连接相关蛋白的表达，iii）抑制TNFRI脱落。总之，我们的数据表明，TACE和TIMP3在人肠屏障中共表达，并且生理或药理上对TACE的抑制都会放大TNF-α介导的高通透性。因此，TIMP3可能通过产生自分泌效应导致上皮屏障高通透性放大，在炎症状态中起主要作用。
