Mechanisms regulating episodic breaches of protective vaginal microbiome by BV

描述(申请人提供)：在拥有健康阴道微生物群的女性中，乳杆菌群落用乳酸酸化阴道，乳酸是一种有效的广谱杀菌剂，可以加强对性传播感染(STI)的粘膜屏障。然而，对于全世界至少三分之一的女性(以及50%的黑人女性)来说，保护性乳杆菌被革兰氏可变细菌和革兰氏阴性细菌的密集混合物所取代，通常会导致一种称为细菌性阴道病(BV)的疾病。BV显著增加了几乎所有性传播感染的易感性，包括艾滋病毒。虽然BV可以用抗生素治疗，但复发频繁，每月约有2次BV发作。阴道细菌群落如何在保护性乳酸菌和非保护性BV之间迅速转移尚不清楚，目前也没有预防BV的方法。这个项目试图找出导致阴道细菌群落快速变化的因素。这些结果可以指导开发急需的方法来预防BV，从而显著降低STI传输率。总体假设是，这些变化是乳杆菌和BV相关细菌之间由分泌的抑制因子介导的拮抗作用的结果；初步证据表明，乳杆菌分泌的乳酸和BV微生物分泌的胺可能是两个这样的因素。为了验证这一假设，将使用qPCR分析来量化体外健康的、以乳酸菌为主的阴道分泌物中存在的抑制BV相关细菌的抑制因子的特异性和效力，以及相反地，存在于体外BV分泌物中的抑制乳酸菌的因子(目标1)。此外，BV的发病动力学(目标2)将是 通过监测乳酸菌的消耗和月经期间或阴道冲洗后阴道分泌物中BV相关细菌抑制的减少(与BV发病有关的两个事件)进行调查。同样，BV缓解(目标3)将通过监测阴道分泌物中的拮抗抑制因子来研究，因为乳酸菌在BV发病后恢复。使用新鲜的、受到最小扰动的体外阴道分泌物来研究抑制因子的作用是一项重大的创新；以前的大多数研究都是在体外生长介质中进行的，未能捕捉到体内存在的细胞(包括共生微生物群落)、抑制因子和粘液的独特混合物。 公共卫生相关性：与患有细菌性阴道病(BV)的女性相比，拥有健康的、以乳酸菌为主的阴道微生物群的女性患重大性传播感染(STI)的风险显著较低，包括HIV、HSV、淋病和滴虫。不幸的是，只有少数女性(约30%)拥有健康的阴道乳杆菌，而在任何给定的时间，大约三分之一的女性都有BV。该项目将有助于揭示健康的乳酸菌是如何被BV相关细菌取代的，并可能支持开发预防BV的方法，从而减少性传播感染。

DESCRIPTION (provided by applicant): In women with a healthy vaginal microbiome, lactobacillus communities acidify the vagina with lactic acid, a potent and broad-spectrum microbicide that reinforces the mucosal barrier to sexually transmitted infections (STIs). However, for at least one-third of women worldwide (and >50 percent of black women), protective lactobacilli are displaced by a dense mixture of Gram-variable and Gram-negative bacteria, often leading to a condition known as bacterial vaginosis (BV). BV markedly increases susceptibility to virtually all STIs, including HIV. Although BV can be treated with antibiotics, relapse occurs frequently, with ~2 BV episodes per month. How vaginal bacterial communities shift rapidly between protective lactobacilli and unprotective BV is not understood, and no method currently exists for preventing BV. This project seeks to identify factors that cause the rapid shifts between vaginal bacterial communities. The results may guide the development of much needed methods to prevent BV and thereby substantially reduce STI transmission rates. The overall hypothesis is that these shifts result from antagonistic actions between lactobacilli and BV-associated bacteria that are mediated by secreted inhibitory factors; preliminary evidence suggests lactic acid secreted by lactobacilli, and amines secreted by BV microbes, may be two such factors. To test this hypothesis, qPCR analysis will be used to quantify the specificity and potency of inhibitory factors present in ex vivo healthy, lactobacillus-dominated vaginal secretions against BV-associated bacteria, and conversely factors in ex vivo BV secretions that inhibit lactobacilli (Aim 1). In addition, the dynamics of BV onset (Aim 2) will be investigated by monitoring the depletion of lactobacilli, and the decrease in inhibition of BV-associated bacteria in vaginal secretions during menses or following vaginal douching (two events associated with BV onset). Similarly, BV remission (Aim 3) will be studied by monitoring antagonistic inhibitory factors in vaginal secretions as lactobacilli recover following a BV episode. The use of fresh, minimally-perturbed ex vivo vaginal secretions to investigate the actions of inhibitory factors represents a significant innovation; most prior research has been performed in vitro in growth media, which fails to capture the unique mixture of cells (including symbiotic microbial communities), inhibitory factors and mucus fluid present in vivo. PUBLIC HEALTH RELEVANCE: Women with a healthy, lactobacillus-dominated vaginal microbiome are at markedly lower risk of major sexually transmitted infections (STIs), including HIV, HSV, Gonorrhea and Trichomonas, than women with bacterial vaginosis (BV). Unfortunately, only a minority of women (~30 percent) have healthy vaginal lactobacilli, while about 1 in 3 women have BV at any given time. This project will help reveal how healthy lactobacilli are displaced by BV-associated bacteria, and will likely support development of methods to prevent BV and thereby reduce STIs.