Molecular cloning and functional analysis of genes associated with mucosal defense to investigate patbophysiology of inflammatory bowel disease

我们鉴定了抵抗素样分子β（RELM-β）和缺失型恶性脑肿瘤1（DMBT 1）作为细菌攻击无菌小鼠诱导的分子，并与肠道植物群的粘膜防御相关。我们研究了这些基因和蛋白在实验性和人类炎症性肠病粘膜组织中的表达及其分子的诱导机制。RELM-β的抗菌活性选择性地在结肠中表达，并由上皮细胞分泌到管腔中。粪便中存在免疫反应性RELM-β，表明该蛋白可能与肠道植物群相互作用。我们通过CFU试验研究了RELM-β是否能够抑制肠道植物群的细菌生长，结果该蛋白对金黄色葡萄球菌具有抗菌能力。即使在通过去除DSS从活动性炎症恢复后，该基因也在DSS-结肠炎中被诱导。北方杂交结果显示，人同源基因DMBT 1在对照中表达较弱，但在2/3的IBD分离株中表达明显。在三分之一的IBD分离株中观察到额外的6.5 kb条带。实时荧光定量RT-PCR结果显示DMBT 1 mRNA在DC和CD中的表达均显著高于正常对照组。然而，免疫组化未发现DMBT 1蛋白表达的质的差异。该基因由IL-1β等可溶性因子诱导表达。

We identified resistin-like molecule β (RELM-β) and deleted malignant brain tumors 1(DMBT1) as molecules induced by bacterial challenge to germ-free mice and associated with mucosal defense against enteric flora. We investigated expression of those genes and proteins in mucosal tissues of experimental and human inflammatory bowel disease and induction mechanisms of the molecules.Antibacterial activity of RELM-βRELM-β was selectively expressed in the colon and secreted from epithelial cells into the lumen. Immunoreactive RELM-β was present in stool, suggesting possible interaction of the protein with enteric flora. We investigated whether or not RELM-β is capable of inhibiting bacterial growth against panels of enteric flora by CFU assay, resulting that this protein exhibited anti-bacterial capacity against Staphylococcus aureus.Epithelial induction of a human homologue of murine CRP-ductin, Deleted in Malignant Brain Tumors 1 (DMBT1)Induction of CRP-ductin mRNA was initially detected by cDNA microarray. This gene was also induced in DSS-colitis even after recovery from active inflammation by the removal of DSS. Northern blotting revealed that the human homologue, DMBT1 with 7 kb in size, was weakly expressed in control but remarkably induced in two-thirds of IBD isolates. An additional 6.5 kb band was noticed in one-third of IBD isolates. Real-time RT-PCR demonstrated that DMBT1 mRNA level was significantly higher in both DC and CD. However, qualitative difference in DMBT1 protein expression was not identified by immunohistochemistry. This gene was induced by soluble factors including IL-1β.