Colonic bacteria express an ulcerative colitis pANCA-related protein epitope
Colonic bacteria express an ulcerative colitis pANCA-related protein epitope
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DOI：
10.1128/iai.68.3.1542-1548.2000
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发表时间：
2000-03-01
影响因子：
3.1
通讯作者：
Braun, J
中科院分区：
文献类型：
--
作者：
Cohavy, O;Bruckner, D;Braun, J
细菌被怀疑是炎症性肠病的致病因素，但相关微生物物种的身份仍未得到解决。pANCA自身抗体与大多数溃疡性结肠炎（UC）病例相关，因此反映了与疾病过程相关的免疫反应。本研究提出了一个假设，即pANCA识别了一种由居住在人类结肠粘膜中的细菌表达的抗原。在好氧和厌氧微生物培养条件下建立大肠细菌文库，使用pANCA单克隆抗体Fab 5-3进行免疫印迹分析，评估细菌池和克隆分离株的交叉反应性抗原。从厌氧文库中检测到两种主要的对pANCA单克隆抗体有免疫反应的蛋白。表达菌的菌落分离物鉴定为卡氏杆菌和大肠杆菌。对该抗原进行分离和部分测序，鉴定出一个100 kda的蛋白，无数据库同源序列。大肠杆菌蛋白经生化和遗传鉴定为外膜孔蛋白OmpC。人血清酶联免疫吸附试验显示，与健康对照组相比，UC患者的免疫球蛋白G抗ompc升高。这些发现表明，pANCA单克隆抗体检测结肠细菌表达的复发蛋白表位，并暗示结肠细菌蛋白是疾病相关免疫反应的靶标。
Bacteria are a suspected pathogenic factor in inflammatory bowel disease, but the identity of the relevant microbial species remains unresolved. The pANCA autoantibody is associated with most cases of ulcerative colitis (UC) and hence reflects an immune response associated with the disease process. This study addresses the hypothesis that pANCA identifies an antigen(s) expressed by bacteria resident in the human colonic mucosa. Libraries of colonic bacteria were generated using aerobic and anaerobic microbiologic culture conditions, and bacterial pools and clonal isolates were evaluated for cross-reactive antigens by immunoblot analysis using the pANCA monoclonal antibody Fab 5-3. Two major species of proteins immunoreactive to pANCA monoclonal antibodies were detected in bacteria from the anaerobic libraries. Colony isolates of the expressing bacteria were identified as Bacteroides caccae and Escherichia coli. Isolation and partial sequencing of the B. caccae antigen identified a 100-kDa protein without database homologous sequences. The E. coli protein was biochemically and genetically identified as the outer membrane porin OmpC. Enzyme-linked immunosorbent assay with human sera demonstrated elevated immunoglobulin G anti-OmpC in UC patients compared to healthy controls. These findings demonstrate that a pANCA monoclonal antibody detects a recurrent protein epitope expressed by colonic bacteria and implicates colonic bacterial proteins as a target of the disease-associated immune response.