MODULATION OF OUTER MEMBRANE PROTEIN EXPRESSION IN HELICOBACTER PYLORI

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 幽门螺杆菌通常会感染胃，在所有人中都会引起炎症(胃炎)，一些人还会患上消化性溃疡或胃癌。幽门螺杆菌与胃上皮细胞的附着是由一个外膜蛋白大家族(OMP)介导的，其中研究最深入的是BABA，它是ABO血型结合粘附素的产物。BABA具有临床意义，因为感染了表达BABA的菌株的患者更有可能发展为消化性溃疡或胃癌。BABAB是一种与BABA密切相关的蛋白质，它与BABA有广泛的5‘和3’同源性，但其功能尚不清楚。我们最近发现，从实验感染的猕猴中恢复的幽门螺杆菌菌株已经失去了BABA的表达。在某些情况下，BABA基因被BABB(一种明显的基因转换事件)取代，而在另一些情况下，由于5‘编码区二核苷酸CT重复数的改变，BABA基因没有表达。缺乏BABA表达的菌株不附着于表达在恒河猴胃上皮细胞上的LEB血型抗原。对人类临床菌株的分析表明，许多患者感染了幽门螺杆菌的变种，其OMP图谱与猕猴的相似。对小鼠的研究表明，在实验感染期间，BABA的表达也会丢失，其动力学与在猕猴中看到的相似。我们推测，幽门螺杆菌OMP表达的这些修饰代表了细菌表面的重塑，以避免宿主免疫或促进与胃上皮细胞的附着。针对这一假设，本文提出了四个具体目标。目的1检测Hp感染猕猴对纯化的BABA和BABB的免疫应答，以探讨免疫逃避在Hp OMP表达选择中的作用。在目标2中，我们将用缺乏BABA或BABB的野生型或等基因突变株来挑战猕猴，并对输出的株系以及宿主基因表达谱进行表征。目的3将利用Rag-/-和Leb转基因小鼠更好地了解获得性免疫和Leb表达在改变OMP表达中的作用。在目标4中，我们将描述BABB的特征，以确定它是作为一种凝集素来介导幽门螺杆菌的附着，还是作为一种蛋白质来调节BABA介导的与血型抗原的结合。这些对Baba和Babb的研究将有助于正在进行的翻译研究，寻求调查Baba和Babb作为候选疫苗的使用，并可能对基因组多样性在促进幽门螺杆菌慢性感染中的作用产生广泛的影响。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Helicobacter pylori commonly infects the stomach, where it causes inflammation (gastritis) in all individuals and peptic ulcer disease or gastric cancer in some. H. pylori attachment to the gastric epithelium is mediated by a large family of outer membrane proteins (OMPs), the best studied of which is BabA, the ABO blood group binding adhesin. BabA is clinically relevant because patients infected with strains that express it are more likely to develop peptic ulcer or gastric cancer. A closely related protein, BabB, shows extensive 5' and 3' homology with BabA, but its function is unknown. We recently showed that H. pylori strains recovered from experimentally infected macaques had lost expression of BabA. In some cases the babA gene was replaced by babB (an apparent gene conversion event) and in other cases the babA gene was not expressed due to alteration in the number of dinucleotide CT repeats in the 5' coding region. Strains lacking BabA expression did not adhere to the Leb blood group antigen that is expressed on rhesus gastric epithelium. Analysis of human clinical strains showed that many patients are infected with variants of H. pylori whose OMP profile resembles that seen in macaques. Studies in mice showed that BabA expression is also lost during experimental infection and the kinetics are similar to what is seen in macaques. We hypothesize that these modifications in H. pylori OMP expression represent a remodeling of the bacterial surface so as to avoid host immunity or promote attachment to the gastric epithelium. Four Specific Aims are proposed to address this hypothesis. Aim 1 will examine the immune response to purified BabA and BabB in H. pylori-infected macaques, in order to address the role of immune evasion in selection of H. pylori OMP expression. In Aim 2 we will challenge macaques with wild type or isogenic mutant strains lacking babA or babB, and characterize the output strains as well as the host gene expression profile. Aim 3 will exploit Rag-/- and Leb transgenic mice to better understand the role of adaptive immunity and Leb expression in modification of OMP expression. In Aim 4 we will characterize BabB to determine whether it may function as a lectin to mediate H. pylori attachment, or, alternatively, as a protein that modulates BabA-mediated binding to blood group antigens. These studies of BabA and BabB will contribute to ongoing translational research that seek to investigate the use of BabA and BabB as vaccine candidates, and also may have broad implications for the role of genome diversity in promoting chronic infection with H. pylori.