CD1a Vaginal Dendritic Cells and HIV-1 Acquisition in the Female Genital Tract

 描述(申请人提供)：世界上大多数新的HIV-1感染是由异性接触后的妇女感染的。在性传播过程中，HIV-1必须穿过生殖器粘膜，在早期的目标细胞中感染和复制，然后从最初的入侵部位传播，从而产生全身感染。HIV-1主要在CD4+淋巴细胞中复制，但这些细胞大多在完整的粘膜表面缺失。基于组织的树突状细胞(DC)被称为朗格汉斯细胞(LCS)，通常被认为有助于HIV-1获得CD4+T细胞。由于组织来源的树突状细胞很难分离，大多数研究使用单核细胞来源的树突状细胞(MDDC)或皮肤来源的LC作为替代物。我们开发了从废弃的阴道组织中分离基于组织的树突状细胞的新方法，称为CD1a+阴道树突状细胞(VDC)。CD1a+VDC具有独特的细胞表面受体、细胞内特性和易感性。最重要的是，我们发现能够利用CCR5受体的HIV-1(称为R5)能够在CD1a+VDC中复制，而使用CXCR4受体的变体(称为X4)则无法感染这些细胞。由于新感染者获得的病毒主要使用CCR5受体，尽管传播伙伴通常利用病毒粒子同时携带R5和CXCR4，我们的数据解释了关于HIV-1感染过程中辅助受体限制的最基本观察结果。我们假设CD1a+VDC将树突投射到阴道腔。这些树突允许CCR5而不是CXCR4使用病毒从阴道腔获得。CD1a+VDC的局部复制促进了病毒跨粘膜上皮向更深层的CD4+T细胞的转移。除了增加HIV-1‘S感染和复制更深层的CD_4+淋巴细胞的能力外，我们假设CD1a+VDC还决定了哪些HIV-1变异体在幼稚宿主中建立了生产性感染。在性传播期间，新感染的对象仅获得在慢性感染的传播伙伴中传播的各种X4和R5病毒的有限数量的R5变体。此外，与传播伙伴中存在的准种相比，感染R5病毒通常具有独特的基因类型和表型。我们假设CD1a+VDC起着守门人的作用，既能阻止X4病毒，又能促进R5变种的复制，这些变种的特性通常在感染后早期分离的HIV-1中发现。在该提案中，我们将研究允许CD1a+VDC对R5敏感但对X4 HIV-1耐药的机制。我们将检查这些细胞是否允许比非传播病毒更优先地复制感染病毒株。我们还将探索可以阻止CD1a+VDC复制和将病毒转移到CD4+T细胞的抑制剂。描述可以防止CD1a+VDC感染或病毒转移到CD4+T细胞的机制细节和因素将提出旨在防止HIV-1粘膜传播的新型疫苗和杀微生物剂策略。

 DESCRIPTION (provided by applicant): The majority of new HIV-1 infections in the world are acquired by women after heterosexual contact. During sexual transmission, HIV-1 must get across the genital mucosa, infect and replicate in the early target cells, and then disseminate from the initial site of invasion to generate a systemic infection. HIV-1 primarily replicates in CD4+ lymphocytes, but these cells are mostly absent from intact mucosal surfaces. Tissue based dendritic cells (DCs), known as Langerhans cells (LCs), are generally believed to facilitate HIV-1 access to CD4+ T cells. Because it has been difficult to isolate tissue based dendritic cells, most studies employ monocyte derived dendritic cells (MDDCs) or skin derived LC as surrogates. We have developed novel methods to isolate tissue based dendritic cells termed CD1a+ vaginal dendritic cells (VDCs) from discarded vaginal tissue. The previously uncharacterized CD1a+ VDCs possess unique cell surface receptors, intracellular features and susceptibility. Most importantly, we show that HIV-1, able to utilize the CCR5 receptor, (termed R5) is able to replicate in CD1a+ VDCs while variants that use the CXCR4 receptor (termed X4) fail to infect these cells. Because viruses acquired by newly infected subjects predominantly use the CCR5 receptor although transmitting partners often harbor both R5 and CXCR4 utilizing virions, our data explains this most fundamental observation about coreceptor restriction during HIV-1 acquisition. We hypothesize that CD1a+ VDC project dendrites into the vaginal lumen. These dendrites allow CCR5 but not CXCR4 using viruses to be acquired from the vaginal lumen. Local replication in CD1a+ VDCs facilitates virus transfer across the mucosal epithelium to deeper lying CD4+ T cells. Besides increasing HIV-1's ability to infect and replicate in deeper lying CD4+ lymphocytes, we hypothesize that CD1a+ VDCs also determine which HIV-1 variants establish a productive infection within a naive host. During sexual transmission, a newly infected subject acquires only a limited number of R5 variants from the diverse X4 and R5 viruses circulating in the chronically infected transmitting partner. In addition, infecting R5 viruses often have unique genotypes and phenotypes compared to the quasispecies present in the transmitting partner. We hypothesize that CD1a+ VDCs function as gate keepers, both blocking X4 viruses and favoring the replication of R5 variants with properties often found among HIV-1 isolated early after infection. In the proposal, we will examine mechanisms that allow CD1a+ VDC to be susceptible to R5 but resistant to X4 HIV-1. We will examine if these cells allow preferential replication of the infecting strains compared to non-transmitted viruses. We will also explore inhibitors that can prevent replication in CD1a+ VDCs and transfer of virus to CD4+ T cells. Delineating the mechanistic details and factors that can prevent infection in CD1a+ VDCs or virus transfer to CD4+ T cells will suggest novel vaccine and microbicide strategies aimed at preventing HIV-1 mucosal transmission.