Lactobacilli as a source of natural microbicides against HIV-1

描述：外用杀微生物剂配制的阴道使用可能有助于阻止进一步传播HIV-1通过减少妇女新感染的数量。正在考虑的一种杀微生物剂策略是加强阴道粘膜中HIV-1传播发生的自然防御。乳酸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，已被证明能在体外灭活HIV-1。乳酸菌也产生一系列抗菌分子，称为细菌素，对当地环境中的竞争生物有效。这些天然抗菌因子是否能抑制HIV-1在阴道组织中的传播和复制尚不清楚。在初步研究中，我们已经发现鼠李糖乳杆菌GG （LGG）培养的条件培养基（CM）在原发CD4+ T淋巴细胞中抑制HIV-1复制2至4 logs10，并且这种抗病毒活性与乳酸和过氧化氢不同。我们假设共生乳酸菌产生的天然细菌素样分子可以增强阴道黏膜的先天免疫，并可以抑制这些靶组织中HIV-1的感染和/或复制。探索性（R21）阶段提出的研究目标是纯化和鉴定LGG细菌产生的低分子量活性因子，并确定LGG纯化因子（LGG- pf）的程度：1)在体外抑制HIV-1的复制，2)调节细胞的活化、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先天免疫因子。在发育（R33）阶段，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感染和先天免疫因子分泌的影响，并将在用于临床前评估阴道局部杀微生物剂的小鼠模型中进一步评估宫颈阴道毒性和炎症。如果经纯化的LGG细菌分泌的因子被证明能在体外抑制相关靶细胞中的HIV-1复制，并调节女性生殖道组织外植体中先天免疫因子的表达，这将为一种新的有益作用提供证据，这种作用远远超出了这些细菌已建立的抗菌功能。此外，这些结果将为乳酸菌衍生产品单独或与阻断HIV-1感染和复制的靶向化合物联合作为HIV杀微生物剂的应用奠定基础。

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.