Hiv, bacterial vaginosis, innate immunology, mucosal immunology, female reproductive tract
Human immunodeficiency virus (HIV) infects 30 million people worldwide. In sub-Saharan Africa, the region most affected by HIV, women comprise 60% of the infected population. Heterosexual transmission is a major mode of viral acquisition, mandating further research of the process and prevention of HIV acquisition via the female reproductive tract (FRT). The FRT is a dynamic environment, protected by host immune mechanisms and commensal microbes. The disruption of either of these elements can increase susceptibility to HIV. Accordingly, one common risk factor for HIV acquisition is the microbial shift condition known as bacterial vaginosis (BV), which is characterized by the displacement of healthy lactobacilli by an overgrowth of pathogenic bacteria. As the bacteria responsible for BV pathogenicity and their interactions with host immunity are not understood, we sought to evaluate the effects of BV-associated bacteria on reproductive epithelia. Here we have characterized the interaction between BV-associated bacteria and the female reproductive tract by measuring cytokine and defensin induction in FRT epithelial cells following bacterial inoculation. Four BV-associated bacteria were evaluated alongside six lactobacilli for a comparative assessment. Our model showed good agreement with clinical BV trends; we observed a distinct cytokine and human β- defensin-2 response to BV-associated bacteria, especially Atopobium vaginae, compared to most lactobacilli. One lactobacillus species, Lactobacillus vaginalis, induced an immune response similar to that elicited by BV-associated bacteria. These iii data provide an important prioritization of BV-associated bacteria and support further characterization of reproductive bacteria and their interactions with host epithelia. We next evaluated the effect of this interaction on HIV infection by investigating the soluble effectors secreted when FRT epithelial cells were cocultured with A. vaginae. We observed increased proviral activity mediated by secreted low molecular weight effectors, and determined that this activity was not likely mediated by cytokine responses. Instead, we identified a complex mixture containing several upregulated host proteins. Selected individual proteins from the mixture exhibited HIV-enhancing activity only when applied with the complex mixture of proviral factors, suggesting that HIV enhancement might be mediated by synergistic effects. In addition to characterizing the immune interactions that mediate the enhanced HIV acquisition associated with BV, we also evaluated the safety and efficacy of RC- 101, a candidate vaginal microbicide being developed for the prevention of HIV transmission. RC-101 has been effective and well tolerated in preliminary cell culture and macaque models. However, the effect of RC-101 on primary vaginal tissues and resident vaginal microflora requires further evaluation. Here, we treated primary vaginal tissues and vaginal bacteria, both pathogenic and commensal, with RC-101 to investigate compatibility of this microbicide with FRT tissue and microflora. RC-101 was well tolerated by host tissues and commensal vaginal bacteria, while BV-associated bacteria were inhibited by RC-101. By establishing vaginal microflora, the specific antibacterial activity of RC-101 may provide a dual mechanism of HIV protection.
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Doctor of Philosophy (Ph.D.)
College of Medicine
Molecular Biology and Microbiology
Length of Campus-only Access
Doctoral Dissertation (Campus-only Access)
Dissertations, Academic -- Graduate Studies, Graduate Studies -- Dissertations, Academic
Eade, Colleen, "Characterization Of Innate Immunity In The Female Reproductive Tract For The Prevention Of Hiv Acquisition" (2013). Electronic Theses and Dissertations. 2960.