Studies on the cellular factors and hormones controlling HIV-1 transmission in an organ culture model

There is very little information available on how HIV-1 transmits through mucosal epithelial layer since it does not express HIV-1 receptor. Overall goal of the project is to elucidate the role of cellular factors and reproductive hormones on HIV-1 transmission across ectocervical and colonic mucosa in an organ culture model. We hypothesize that upon exposure to HIV-1, a complex signal transduction network is activated in epithelial cells, which leads to compromised barrier function by disrupted tight junctions and expression of immune mediators, which would recruit immune cells towards the epithelial layer for replication of virus. Furthermore, reproductive hormone might have an effect on HIV-1 acquisition risk. To test the hypothesis, we evaluated in context of tissue structure whether HIV-1 induces tight junction disruption in ectocervical and colon epithelial cells, examined the cellular factors, including inflammatory cytokines that are involved in HIV-1 transmission across ectocervical epithelia and evaluated the effect of reproductive hormone on HIV-1 transmission. Our results in aim 1 showed that after exposure to HIV-1, no significant changes in the tight junction/adherens junction protein expression were observed in ectocervical and colon epithelia. However, these tissues were infected after exposure to HIV-1. Our data thus indicate that HIV-1 transverses the ectocervical/colon mucosal epithelia without profoundly disrupting the tight junction/adherens junction between epithelial cell. In aim 2, we found that after HIV-1 exposure, the level of CXCL10 and CXCL11 messages in ectocervical epithelia were upregulated and such induction of cytokines in ectocervical epithelia was dependent on HIV-1 infectivity. Furthermore, we measured the expression level of cellular factors in HIV-1 exposed ectocervical epithelia by next generation sequencing. Our results indicate that, cellular genes like IL36A, FMO2, CXCL10, MUC1, SAA1 and IL8 were differentially expressed in ectocervical epithelia exposed to HIV-1 compared to controls. These results suggest that exposure to HIV-1 induces cytokine production and other cellular factors in epithelial cells. In aim 3, we investigated the impact of reproductive hormones on the risk of HIV-1 acquisition by analyzing the susceptibility of ectocervical/vaginal tissues to HIV-1 infection and by comparing the epithelial thickness/tight junction protein expression in ectocervical/vaginal tissues at different phases of menstrual cycle. Our results showed no difference in HIV-1 susceptibility, epithelial layer thickness and tight junction/adherence junction protein expression levels in ectocervical/vaginal tissues at different stages of the menstrual cycle. Taken together, our results suggest that risk of HIV-1 infection in the ectocervical/vaginal region does not vary over the course of menstrual cycle. These findings are of public health importance because they expand our understanding on mechanism of atraumatic HIV-1 transmission in mucosal area that may be important for developing effective strategies for preventing HIV-1 transmission

Effect of early anti-retroviral therapy on the pathogenic changes in mucosal tissues of SIV infected rhesus macaques

<p>Abstract</p> <p>Background</p> <p>The gastrointestinal tissue plays an important role in the pathogenesis of HIV/SIV infection and serves as a viral reservoir in infected individuals under antiretroviral therapy (ART). However, the effect of ART administration in the very early stage of infection on HIV/SIV replication and pathogenesis in gastrointestinal tissue has not been fully studied. In this current study, rhesus monkeys infected with SIV were treated with ART starting at day 7 post-infection. The effect of early ART on SIV replication and infection-related pathogenic changes in mucosal tissues of the infected monkeys was examined.</p> <p>Methods</p> <p>Nuclear acids were extracted from snap frozen ileum and colon tissues and mesentery lymph nodes from SIV infected monkeys with or without ART. SIV RNA and DNA loads as well as levels of CD3, CD4 and cytokine mRNA were measured by PCR and RT PCR from the isolated nuclear acids. Tissue sections were stained by immuno-fluorescence labeled antibodies for CD3 and CD4.</p> <p>Results</p> <p>Without ART treatment, these monkeys underwent a mild SIV infection with low viral loads and slightly decreased CD4⁺ T cell counts in peripheral blood. In ART treated monkeys, SIV RNA loads were undetectable in blood with normal CD4⁺ T cell counts, however, SIV RNA and DNA were detected in the intestinal tissues and mesentery lymph nodes although the levels were lower than those in untreated monkeys. The levels of CD3 and CD4 positive cells in the tissues were similar between the infected untreated monkeys and infected ART treated monkeys based on RT-PCR and immune-fluorescence staining of the tissue sections. Furthermore, compatible levels of IL-6, TNF-a, IL-1b and MyD88 mRNAs were detected in most of intestinal tissues and mesentery lymph nodes of infected ART treated and infected untreated monkeys.</p> <p>Conclusions</p> <p>These results suggest that early ART administration could not effectively inhibit SIV replication in intestinal tissues and mesentery lymph nodes and could not reduce the immune activation induced by SIV infection in the intestinal tissues.</p