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

 描述（由申请人提供）：世界上大多数新的HIV-1感染是由女性在异性接触后获得的。在性传播过程中，HIV-1必须穿过生殖器粘膜，在早期靶细胞中感染和复制，然后从最初的侵入部位传播，产生全身感染。HIV-1主要在CD 4+淋巴细胞中复制，但这些细胞大多不存在于完整的粘膜表面。基于组织的树突状细胞（DC），称为朗格汉斯细胞（LC），通常被认为促进HIV-1接近CD 4 + T细胞。由于难以分离基于组织的树突状细胞，大多数研究采用单核细胞衍生的树突状细胞（MDDC）或皮肤衍生的LC作为替代物。我们已经开发了新的方法来分离组织为基础的树突状细胞称为CD 1a+阴道树突状细胞（VDC）从废弃的阴道组织。以前未表征的CD 1a + VDCs具有独特的细胞表面受体、细胞内特征和易感性。最重要的是，我们表明，能够利用CCR 5受体（称为R5）的HIV-1能够在CD 1a + VDC中复制，而使用CXCR 4受体（称为X4）的变体无法感染这些细胞。由于新感染受试者获得的病毒主要使用CCR 5受体，尽管传播伙伴通常同时携带R5和CXCR 4利用病毒体，我们的数据解释了HIV-1获得过程中关于辅助受体限制的最基本观察结果。我们假设CD 1a + VDC向阴道腔投射树突。这些树突允许使用病毒从阴道腔获得CCR 5而不是CXCR 4。CD 1a + VDC中的局部复制促进病毒穿过粘膜上皮转移到更深处的CD 4 + T细胞。除了增加HIV-1在更深处的CD 4+淋巴细胞中感染和复制的能力外，我们假设CD 1a + VDCs还决定了哪些HIV-1变体在初始宿主中建立了生产性感染。在性传播期间，新感染的受试者仅从慢性感染的传播伴侣中传播的不同X4和R5病毒获得有限数量的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型和表型。我们假设CD 1a + VDCs作为守门人发挥作用，既阻断X4病毒，又有利于R5变异体的复制，这些变异体具有感染后早期分离的HIV-1中常见的特性。在该提案中，我们将研究允许CD 1a + 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优先复制的感染株相比，非传播病毒。我们还将探索可以阻止CD 1a + VDC复制和病毒转移到CD 4 + T细胞的抑制剂。描述可以防止CD 1a + VDCs感染或病毒转移到CD 4 + T细胞的机制细节和因素，将提出旨在预防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.