Roles of carbonic anhydrase isozymes in the pathogenesis of pancreatitis and pancreas cancer.

我们成功地获得了两个CA同工酶（CA VB和XIV）和两个CA相关蛋白（CA RP X和Xi）的新cDNA克隆。生化分析表明，CA VB为线粒体同工酶，CA XIV为跨膜同工酶。由于CA-RP X和Xi缺少对CA催化活性至关重要的三个锌结合组氨酸残基中的至少一个，因此它们被认为是无催化蛋白。在人胰腺中鉴定了CA II、IV、VB、VI、Xi、XII、CA-RP X和Xi的mRNA表达。免疫组化分析与单克隆抗体三CA-RP显示阳性染色的胰腺外分泌细胞中只有CA-RP VIII。本文和以前的研究结果表明，CA II，IV，IS和XII在胰腺导管上皮细胞中的显着表达。基于上述结果，我们研究了CA II，IV，IX和XII作为靶抗原在自身免疫性胰腺炎（AIP）发病机制中的作用。采用免疫印迹法检测80例原发性慢性胰腺炎（ICP）患者和30例正常对照者血清中的抗体。结果表明，ICP患者血清抗CA Ⅱ和抗CA Ⅳ抗体阳性率分别为30%和5%，NC患者分别为10%和3%。在所有ICP患者和NC中均未观察到抗CA IX和XII的血清抗体。CA II广泛分布于几乎所有的组织类型，但CA IV表达相对有限的外分泌器官的导管上皮细胞。考虑到AIP及其并发症（Sjogren综合征和原发性硬化性胆管炎）的病理学表现为“胆管炎”，我们的研究结果表明CA IV是AIP发病机制中起重要作用的候选抗原。

We successfully obtained novel cDNA clones of two CA isozymes (CA VB and XIV) and two CA-related proteins (CA-RP X and XI). Biochemical analysis indicated that CA VB was a mitochondrial isozyme and CA XIV was a transmembrane isozyme. Since CA-RP X and XI lack at least one of three zinc-binding histidine residues which are critical for the CA catalytic activity, they were though to be acatalytic proteins. mRNA expressions of CA II, IV, VB, VI, XI, XII, CA-RP X, and XI were identified in the human pancreas. Immunohistochemical analyzes with monoclonal antibodies to three CA-RPs showed positive staining of only CA-RP VIII in pancreatic exocrine cells. The results obtained herein and in previous studies indicate the significant expression of CA II, IV, IS, and XII in ductal epithelial cells of the pancreas.Based on the results described above, we studied roles of CA II, IV, IX and XII as a target antigen in the pathogenesis of autoimmune pancreatitis (AIP). Western blot analyzes were employed to identify serum antibody in patients with idiopathic chronic pancreatitis (ICP, n=80) and normal controls (NC, n=30). In result, serum antibodies to CA II and IV were seen in 30 % and 5 % in ICP and 10 % and 3 % in NC, respectively. Serum antibodies to CA IX and XII were not observed in all ICP patients and NC. CA II is widely distributed in almost of all tissue types but CA IV expression is relatively limited in ductal epethelial cells of exocrine organs. In consideration with the fact that AIP and its complications (Sjogren's syndrome and primary sclerosing cholangitis) pathologically showed "ductulitis", our results suggest that CA IV is a candidate antigen playing an important role in the pathogenesis of AIP.