| Summary: | Thesis (Ph.D.)--Boston University === HIV-infected macrophages are frequently present in semen of untreated HIV-infected men. After intercourse, there is evidence that these cells infiltrate from the vaginal epithelial surface into the mucosa (apical to basal infiltration) and transmit HIV to a new host. Since women with cervicovaginal inflammation are at an increased risk of acquiring HIV, we hypothesized that epithelial inflammation enhances cell-associated HIV transmission via increased seminal leukocyte infiltration into the vaginal mucosa. In order to investigate this mechanism, we utilized an in vitro reconstructed human vaginal epithelium that is structurally similar to normal human mucosa. We have used confocal microscopy to characterize the kinetics of apical to basal infiltration of Phorbol-12- myristate-13-acetate activated U937 macrophages as well as non-infected and HIV-infected primary monocyte-derived macrophages (MDMs) through this vaginal mucosal model. Within two hours of placement on the apical side of the epithelium, both non-infected and HIV-infected macrophages were abundant within the uppermost cell layers (stratum corneum) and a subpopulation of these cells were observed to have infiltrated through intact epithelial junctions to reach depths ranging from 50-200 µm. Infiltration of both non-infected and infected cells was significantly enhanced when the Epivaginal tissues were pre-treated with TNF-alpha, an important pro-inflammatory cytokine. Through microarray analysis and Enzyme-linked immunosorbent assay (ELISA), we demonstrated that exposure to TNF-alpha upregulated transcription and/or expression of several chemotactic factors and matrix metalloproteases, the presence of which may have contributed to increased leukocyte infiltration into inflamed epithelium. Additionally, TNF-alpha treatment resulted in a dramatic increase in epithelial expression of intercellular adhesion molecule 1 (ICAM-1).
These data provide evidence that HIV-infected macrophages can infiltrate into the normal human vaginal epithelium from the vaginal lumen after intercourse, and that cervicovaginal inflammation enhances infiltration. These studies provide further insight into potential mechanisms of cell-associated HIV transmission and suggest that strategies to inhibit vaginal inflammation, and/or block leukocyte attachment and infiltration may be a relevant approach to prevent HIV transmission.
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