The Role of Exosomes in Semen for HIV Infection in the Genital Mucosa of Women

描述(由申请人提供)：将女性生殖道暴露在感染艾滋病毒-1的精液中是异性传播艾滋病毒的主要途径。对这一过程的详细了解对于开发疫苗和预防性局部杀微生物剂至关重要。在这项建议中，我们研究了精液中的小膜泡在HIV传播和诱导宫颈阴道免疫反应中的作用。在所有研究的体液中，精液中外切体的浓度是最高的，但人们对这些颗粒的生物学知之甚少。我们的初步研究表明，精液外切体与精浆中的无细胞HIV-1病毒粒子结合，并增强HIV-1的感染性。此外，精液外切体在接触后迅速进入阴道朗格汉斯细胞(LCS)。在这些发现的基础上，我们将使用极化和非极化的体外宫颈阴道移植模型，直接研究精液外切体在女性生殖器粘膜中潜在的三种感染促进模式：上皮内靶细胞的生产性HIV感染，HIV渗透到宫颈阴道上皮，以及HIV进入阴道LCS。鉴于已报道的精液外切体的免疫抑制特性，我们还将研究当精液外切体入侵LCS时，LC介导的适应性T细胞对同种抗原或召回抗原的反应是否被钝化。如果精液外切体促进艾滋病毒的性传播，杀菌预防策略可能包括阻止病毒粒子-外切体相互作用或阻止外切体穿透粘膜。如果阴道LCS对精液外切体的处理使生殖器免疫系统对外来抗原耐受，粘膜免疫策略可能会从控制这种影响中受益。 公共卫生相关性：在世界范围内，大多数艾滋病毒感染是通过与含有HIV-1的精子性接触后的生殖器或肠道内壁发生的。因此，需要关于人类精液中影响HIV-1感染粘膜靶细胞能力的因素的信息，以帮助制定预防的医学策略，如疫苗或当地提供的抗病毒药物。在这项提议中，我们计划研究精液中微小但丰富的膜小泡(称为外体)是否对艾滋病毒感染和阴道免疫反应的诱导有影响。如果精液中的外切体促进了艾滋病毒的性传播或削弱了对艾滋病毒感染和疫苗接种的免疫反应，这些致病途径的准确定义将为防止性传播艾滋病毒的预防策略提供依据。

DESCRIPTION (provided by applicant): Exposure of the female genital tract to HIV-1-infected semen is the primary route of heterosexual HIV transmission. Gaining a detailed understanding of this process is critical for developing vaccines and prophylactic topical microbicides. In this proposal, we investigate the effect of small membrane vesicles in semen, seminal exosomes, on HIV transmission and the induction of cervicovaginal immune responses. Semen has the highest concentration of exosomes among all body fluids studied, but relatively little is known about the biology of these particles. Our preliminary studies show that seminal exosomes associate with cell-free HIV-1 virions in seminal plasma and enhance HIV-1 infectivity. Moreover, seminal exosomes rapidly enter vaginal Langerhans cells (LCs) upon contact. Building on these findings, we will directly study three modes of potential infection enhancement by seminal exosomes in the female genital mucosa, using both a polarized and a non-polarized ex vivo cervicovaginal explant model: productive HIV infection of intraepithelial target cells, HIV penetration into the cervicovaginal epithelium, and HIV entry into vaginal LCs. Given the reported immunosuppressive properties of seminal exosomes, we will also investigate whether LC-mediated adaptive T-cell responses to alloantigens or recall antigens are blunted when seminal exosomes invade the LCs. If seminal exosomes facilitate sexual HIV transmission, microbicidal prevention strategies could include a blockade of virion-exosome interactions or an inhibition of exosome penetration into the mucosa. If processing of seminal exosomes by vaginal LCs tolerizes the genital immune system to foreign antigens, mucosal vaccination strategies could benefit from controlling this effect. PUBLIC HEALTH RELEVANCE: Worldwide, most HIV infections occur through the linings of the genital or intestinal tract following sexual contact with HIV-1-containing semen. Information about the factors in human semen that influence the ability of HIV-1 to infect target cells in the mucosa is therefore needed to help in devising medical strategies for prevention, such as vaccines or locally delivered antiviral drugs. In this proposal, we plan to study whether small but abundant membrane vesicles in semen, termed exosomes, have an effect on HIV infection and the induction of immune responses in the vagina. If exosomes in semen facilitate sexual HIV transmission or blunt the immune response to HIV infection and vaccination, an exact definition of these pathogenic pathways will inform prevention strategies against sexual HIV transmission.