MEMBRANE-BINDING COMPLEMENT REGULATORY FACTER IN GASTROINTESTINAL TRACT

在这项研究中，补体及其调节系统在大鼠、人和豚鼠的胃肠道中进行了研究。应用眼镜蛇毒素因子(CVF)和/或CP抑制剂，研究补体和血浆C3a、C5a失活因子在肠缺血后全身休克中的作用。CVF可预防休克的发生，但CP抑制剂加重了这种休克。在人胃粘膜中，补体膜结合抑制因子(DAF)在胃炎过程中不受调节。对豚鼠胃粘膜的研究表明，在胃I/R后，DAF基因和蛋白的表达发生了变化。正常豚鼠胃粘膜中DAF基因的表达呈结构性变化，在I/R后6小时表达最强，但在24小时、3天和7天检测到正常水平。DAF蛋白在I/R后0~12h表达不明显，但在24小时和3d表达增加，7d恢复到不显著水平。用6种亚型(跨膜型；跨膜型；TM-a、TM-ab、TM-ABC和糖基磷脂酰肌醇锚定型；GPI-a、GPI-ab、GPI-ABC)的特异性引物RT-PCR检测DAF异构体mRNA的表达。正常豚鼠胃粘膜有GPI-a、GPI-ab、GPI-ABC、Tm-a和Tm-ab的信使RNA，而Tm-ABC的信使RNA未见表达。然而，在I/R后6小时，Tm-ABC的mRNAs开始被检测到，Tm-a和Tm-ab是优势种。我们还评估了补体在大鼠缺血诱导的胃粘膜损伤模型中的作用。CVF和补体作用的抑制剂K-76 COOH可显著减轻再灌流后的粘膜损伤，这些结果支持补体及其调节系统在胃肠道病理中可能起重要作用。

In this study, complement and its regulatory system were investigated in the rat, human, and guinea pig gastrointestinal tract. Roles of complement and plasma carboxypeptidase (CP ; inactivator of C3a and C5a) in systemic shock following intestinal ischemia were studied using cobra venom factor (CVF,which reduced serum complement to undetectable level) and/or CP inhibitor. Pretreatment with CVF prevented, but CP inhibitor aggravated such a shock. In human gastric mucosa, DAF (membrane binding inhibitor of complement) was found to be unregulated during gastritis. The study on guinea pig gastric mucosa clearly demonstrated alternation in the expression of DAF gene and protein after gastric I/R.Expression of DAF mRNA was constitutively demonstrated in normal guinea pig gastric mucosa and was most intense in 6hr after I/R.However, it was detected at normal levels at 24 hr, 3 and 7 days. Expression of DAF protein was not significant from 0 to 12 hr after I/R but it was increased in amount at 24 hr and 3 days, returning to less than significant levels at 7 days. Expression of DAF isoform mRNA was also assessed by RT-PCR with specific primers for 6 isoforms (transmembrane types ; TM-a, TM-ab, TM-abc, and glycosylphosphatidyl-inositol anchored types ; GPI-a, GPI-ab, GPI-abc) were evaluated. Messenger RNAs for GPI-a, GPI-ab, GPI-abc, TM-a and TM-ab were constitutively detected in normal guinea pig gastric mucosa, whereas mRNA for TM-abc was not. However, 6 hr after I/R,mRNAs for TM-abc became detectable, with TM-a and TM-ab the dominant species. We also evaluated role of complement in a rat model for ischemia-induced gastric mucosal injury. Pretreatments with CVF and K-76 COOH,a inhibiter of complement action, significantly attenuated mucosal injury observed after reperfusion.These findings support that complement and its regulatory system may play a significant role in pathology of gastrointestinal tract.