MODULATION OF OUTER MEMBRANE PROTEIN EXPRESSION IN HELICOBACTER PYLORI

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 幽门螺杆菌通常感染胃，在所有个体中引起炎症（胃炎），在一些个体中引起消化性溃疡疾病或胃癌。H.幽门螺杆菌与胃上皮的附着是由一个大家族的外膜蛋白（OMP）介导的，其中研究得最好的是BabA，ABO血型结合粘附素。BabA与临床相关，因为感染表达它的菌株的患者更有可能发展为消化性溃疡或胃癌。一个密切相关的蛋白质，BabB，显示广泛的5'和3'同源性与BabA，但其功能是未知的。我们最近发现H.从实验感染的猕猴中回收的pylori菌株失去了BabA的表达。在某些情况下，babA基因被babB取代（一种明显的基因转换事件），而在其他情况下，由于5'编码区中二核苷酸CT重复序列数量的改变，babA基因不表达。缺乏BabA表达的菌株不粘附于在恒河猴胃上皮上表达的Leb血型抗原。对人类临床菌株的分析表明，许多患者感染了H. pylori，其OMP谱类似于在猕猴中看到的。在小鼠中的研究表明，BabA表达在实验感染期间也会丢失，并且动力学与在猕猴中观察到的相似。我们推测，这些修改在H。幽门螺杆菌OMP表达代表细菌表面的重塑，以避免宿主免疫或促进附着到胃上皮。提出了四个具体目标来解决这一假设。目的一是检测纯化的BabA和BabB在H. pylori感染的猕猴，以解决免疫逃避在H. pylori OMP表达。在目标2中，我们将用缺乏babA或babB的野生型或同基因突变株攻击猕猴，并表征输出菌株以及宿主基因表达谱。目的3利用Rag-/-和Leb转基因小鼠，进一步了解获得性免疫和Leb表达在OMP表达调节中的作用。在目标4中，我们将描述BabB的特征，以确定它是否可以作为凝集素介导H。pylori附着，或者，可替代地，作为调节BabA介导的与血型抗原结合的蛋白质。这些对BabA和BabB的研究将有助于正在进行的转化研究，这些研究旨在研究BabA和BabB作为候选疫苗的用途，并且还可能对基因组多样性在促进H.幽门。

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.