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

描述（由申请人提供）：女性生殖道暴露于HIV-1感染的精液是异性间HIV传播的主要途径。详细了解这一过程对于开发疫苗和预防性局部杀微生物剂至关重要。在这个提议中，我们研究了精液中的小膜囊泡（精液外泌体）对HIV传播和诱导宫颈阴道免疫反应的影响。在所有研究的体液中，精液的外泌体浓度最高，但对这些颗粒的生物学知之甚少。我们的初步研究表明，精液外泌体与精浆中的无细胞HIV-1病毒粒子相关，并增强HIV-1的感染性。此外，精液外泌体在接触后迅速进入阴道朗格汉斯细胞（LC）。基于这些发现，我们将使用极化和非极化离体宫颈阴道外植体模型直接研究女性生殖器粘膜中精液外泌体的三种潜在感染增强模式：上皮内靶细胞的生产性HIV感染，HIV渗透到宫颈阴道上皮中，以及HIV进入阴道LC。鉴于所报道的精液外泌体的免疫抑制特性，我们还将研究当精液外泌体侵入LC时，LC介导的对同种抗原或回忆抗原的适应性T细胞应答是否减弱。如果精液外泌体促进了HIV的性传播，那么杀微生物的预防策略可能包括阻断病毒体-外泌体相互作用或抑制外泌体渗透到粘膜中。如果阴道LC对精液外泌体的处理使生殖器免疫系统耐受外来抗原，那么粘膜疫苗接种策略可以从控制这种效应中受益。 公共卫生相关性：在世界范围内，大多数艾滋病毒感染发生在与含有HIV-1的精液发生性接触后的生殖器或肠道内壁。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，以帮助制定预防医学策略，如疫苗或局部递送的抗病毒药物。在这项提案中，我们计划研究精液中小但丰富的膜囊泡（称为外泌体）是否对HIV感染和阴道免疫反应的诱导产生影响。如果精液中的外泌体促进了性传播或减弱了对HIV感染和疫苗接种的免疫反应，那么这些致病途径的确切定义将为预防性传播HIV的策略提供信息。

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.