Gut Homing Cells in SIV infection

描述（由申请方提供）：急性HIV/SIV期间肠道相关淋巴组织（GALT）内的CD 4 + T细胞大量耗竭，随后在慢性感染期间持续CD 4 + T细胞丢失，导致GALT和上覆粘膜上皮的进行性损伤。这些事件会导致免疫功能障碍、病毒载量和疾病进展速度。CD 4 + T细胞通过GALT内产生的信号向GALT运输，所述信号包括释放视黄酸，所述视黄酸反过来导致GALT的上调。四个？7整合素和CCR 9在细胞表面的表达。细胞表达？四个？7和CCR 9通过与肠壁上皮细胞表达的同源受体MAdCAM和CCL 25相互作用而选择性地归巢于GALT。最近的数据显示，？四个？7，除了作为归巢受体，也作为一个替代受体的许多株艾滋病毒和SIV的V1/V2的env节段有识别“基序”？四个？7类似于MAdCAM其天然配体。此外，定位于V1/V2和V3/C4 env区的序列含有残基，如果去糖基化，则显著增强病毒结合的亲和力。四个？7.这样的？四个？7高亲和力结合HIV-1被认为优先通过粘膜途径传播。我们的实验室最近表明，灵长类抗？？四个？在急性IV和直肠内SIV感染之前和期间，7 mAb导致GALT中的病毒载量显著降低，并首次提供了详细检查急性感染期间发生的事件的工具。本文提出的研究的目的是：1）确定这些以前的研究结果的临床效用，确定是否？四个？7施用有效降低动物中的GALT病毒载量，a）阴道内感染，B）SIV感染后，c）阴道内用低重复剂量感染以模拟自然传播，和d）如果CCR 9的小分子抑制剂单独或与？四个？7 mAb给药导致GALT病毒血症的更有效和更长时间的控制; 2）定义肠道组织的组织病理学分析，重点是描述参与维持肠道组织完整性的蛋白质的作用，定义细菌移位的动力学和肠道组织渗透性的生理学测量;和3）确定所涉及的机制，四个？7通过确定是否产生了其效果a）。四个？7单抗通过阻断受体功能介导其作用。四个？第七条禁止贩卖？四个？7表达细胞使用重组复制能力的SIV env构建体，做或不结合？四个？7、B）通过测定抗？四个？7处理受env糖基化水平的影响。和重组env去糖基化的SHIV结合？四个？7具有低v/s高亲和力，c）确定对照和？四个？使用我们实验室开发的最新优化的真实的实时“LIVE”PET-CT扫描技术对7只给药动物进行扫描。认识到有效的HIV疫苗不仅需要引起广泛的中和抗体和有效的病毒特异性CTL，而且还需要防止与疾病进展密切相关的GALT损伤，突出了这些研究的重要性。

DESCRIPTION (provided by applicant): The massive depletion of CD4+ T cells within the gut associated lymphoid tissues (GALT) during acute HIV/SIV followed by sustained CD4+ T cell loss during chronic infection leads to progressive damage to the GALT and the overlying mucosal epithelium. These events contribute to immune dysfunction, viral loads and the rate of disease progression over time. The CD4+ T cells traffic to the GALT by signals generated within the GALT which include the release of retinoic acid which in turn leads to upregulation of the ?4?7 integrin and CCR9 on the cell surface. Cells expressing ?4?7 and CCR9 selectively home to the GALT by interacting with their cognate receptors MAdCAM and CCL25 expressed by epithelial cells lining the intestinal wall. Recent data show that ?4?7, besides serving as the homing receptor, also serves as an alternate receptor for many strains of HIV and SIV whose V1/V2 env segments have recognition 'motifs' for ?4?7 similar to MAdCAM its natural ligand. In addition, sequences localized to the V1/V2 and V3/C4 env region contain residues which, if deglycosylated, markedly enhance the affinity of the virus to bind ?4?7. Such ?4?7 high affinity binding HIV-1 is thought to be preferentially transmitted via the mucosal route. Our lab has recently shown that the administration of a primatized anti??4?7 mAb, just prior to and during acute IV and intra-rectal SIV infection, leads to markedly reduced viral loads in the GALT and provides, for the first time, tools to examine in detail the events that occur during acute infection. The studies proposed herein are aimed at: 1) determining the clinical utility of these previous findings by determining if ?4?7 administration is effective in lowering GALT viral loads in animals a) infected intravaginally, b) post SIV infection, c) infected with low repeated doses intravaginally to mimic natural transmission, and d) if a small molecule inhibitor of CCR9 alone or with ?4?7 mAb administration leads to more effective and prolonged control of GALT viremia; 2) defining the histopathological analysis of the gut tissues with a focus on delineating the role of proteins involved in maintaining gut tissue integrity, defining the kinetics of bacteril translocation and the physiologic measurement of gut tissue permeability; and 3) determining the mechanisms involved by which ?4?7 induces its effect a) by determining whether ?4?7 mAb mediates its effect via blocking the receptor function of the ?4?7 or by blocking the trafficking of ?4?7 expressing cells by using recombinant replication competent SIV env constructs that do or do not bind ?4?7, b) by determining whether the in vivo effect of anti-??4?7 treatment is influenced by the level of env glycosylation using W.T. & recombinant env deglycosylated SHIV's that bind ?4?7 with low v/s high affinity, c) determine the tissue/organ localization of virus and CD4+ cells in the control and ?4?7 administered animals using a newly optimized real time "LIVE" PET-CT scanning technique developed by our lab. The realization that effective HIV vaccines require to elicit not only broad neutralizing Abs and effective virus specific CTL's but also means to prevent GALT injury which is intimately associated with disease progression, highlight the importance of these studies.