Lactobacilli as a source of natural microbicides against HIV-1

描述：用于阴道使用的局部杀微生物剂可以通过减少妇女新感染的数量来帮助阻止HIV-1的进一步传播。一种正在考虑的杀微生物剂策略是加强发生HIV-1传播的阴道粘膜的自然防御。乳杆菌是健康女性生殖道分泌物中的主要共生菌。在厌氧条件下，这些细菌产生乳酸，某些菌株还产生过氧化氢，过氧化氢是一种有效的抗菌剂，已被证明在体外可以使HIV-1失活。乳酸菌还产生一系列被称为细菌素的抗微生物分子，这些分子能有效地对抗当地环境中的竞争生物。目前尚不清楚这些天然抗菌因子能否抑制HIV-1在阴道组织中的传播和复制。在初步研究中，我们发现来自鼠李糖乳杆菌(Lactobacillusrhamnosus GG，LGG)的条件培养液(CM，Lactobacillusrhamnosus GG，LGG)可抑制HIV-1在原代CD4+T淋巴细胞中复制2-4logs10，这种抗病毒活性有别于乳酸和过氧化氢。我们推测，共生乳酸菌产生的天然类细菌素分子(S)可以增强阴道粘膜的天然免疫，并能抑制HIV-1在这些靶组织中的感染和/或复制。在探索阶段(R21)提出的研究目标是纯化和鉴定LGG细菌产生的低分子活性因子(S)，并确定LGG纯化因子(LGG-PF)的程度：1)抑制HIV-1的体外复制，2)调节细胞激活、增殖和转录调节，3)影响人类女性生殖道原代上皮细胞分泌天然免疫因子。在发育阶段(R33)，我们将评估LGG-PF对人类宫颈和阴道组织原代外植体培养中HIV-1感染和天然免疫因子分泌的影响，并将在为临床前评估局部阴道杀菌剂而开发的小鼠模型中进一步评估宫颈阴道毒性和炎症。如果免疫球蛋白细菌分泌的纯化因子(S)在体外抑制HIV-1在相关靶细胞中的复制，并调节女性生殖道组织外植体中天然免疫因子的表达，这将为进一步研究这些细菌已有的抗菌功能提供新的有益效果的证据。此外，这些结果将为乳酸菌衍生产品作为艾滋病毒杀微生物剂的应用奠定基础，无论是单独使用还是与阻断艾滋病毒-1感染和复制的目标化合物结合使用。

DESCRIPTION: Topical microbicides formulated for vaginal use may help stem further spread of HIV-1 by reducing the number of new infections in women. One microbicide strategy under consideration is to strengthen the natural defenses in the vaginal mucosa where HIV-1 transmission takes place. Lactobacillus species are the predominant commensal bacteria found in genital tract secretions of healthy women. Under anaerobic conditions, these bacteria produce lactic acid and certain strains also produce hydrogen peroxide, a potent antimicrobial that has been shown to inactivate HIV-1 in vitro. Lactic acid bacteria also produce an array of antimicrobial molecules, termed bacteriocins, that are effective against competing organisms in the local milieu. Whether these natural antimicrobial factors can inhibit transmission and replication of HIV-1 in vaginal tissues is unknown. In preliminary studies, we have shown that conditioned media (CM) from cultures of Lactobacillus rhamnosus GG (LGG) inhibits replication of HIV-1 by 2 to 4 logs10 in primary CD4+ T lymphocytes, and this antiviral activity is distinct from both lactic acid and hydrogen peroxide. We hypothesize that natural bacteriocin-like molecule(s) produced by commensal lactic acid bacteria can enhance innate immuity in the vaginal mucosa and can inhibit infection and/or replication of HIV-1 in these target tissues. The goal of studies proposed in the exploratory (R21) phase is to purify and identify the low molecular weight active factor(s) produced by LGG bacteria, and determine the extent to which the LGG-purified factors (LGG-PF): 1) inhibit replication of HIV-1 in vitro, 2) modulate cell activation, proliferation and transcriptional regulation, and 3) affect the secretion of innate immune factors from primary epithelial cells from the human female reproductive tract. In the developmental (R33) phase, we will evaluate the effect of LGG-PF on HIV-1 infection and secretion of innate immune factors in primary explant cultures of human cervical and vaginal tissues, and will further evaluate cervicovaginal toxicity and inflammation in a mouse model developed for preclinical evaluation of topical vaginal microbicides. If the purified factor(s) secreted by LGG bacteria are shown to inhibit HIV-1 replication in relevant target cells in vitro, and modulate expression of innate immune factors in female genital tract tissue explants, this would provide evidence of a novel and beneficial effect that extends well beyond the established antimicrobial function of these bacteria. Moreover these results would lay the foundation for application of lactobacilli-derived products as HIV microbicides either alone or in combination with targeted compounds that block HIV-1 infection and replication.