ABSTRACT: HIV-1 infections of women are mainly acquired through female reproductive tract where cervical and vaginal epithelial cells are the first line of defense. Although HIV-1 does not directly infect epithelial cells, HIV-1 obligatorily interacts with and crosses over epithelial layer to infect susceptible target cells, mainly CD4+ T cells, in the lamina propria to initiate an infection. However, the mechanism and ramification of the interaction of HIV-1 and epithelial cells in vaginal transmission of HIV-1 remain to be elucidated. We hypothesized that cervical epithelial cells are not a passive barrier, but actively respond to HIV-1 to change mucosal milieu and facilitate HIV-1 transmission. We tested this hypothesis by studying the responses of cervical epithelial cells to HIV-1 through profiling genome-wide transcription. We found 1) cervical epithelial cells actively respond to HIV-1. Five hundred forty-three transcripts/genes in cervical epithelial cells were significantly altered in expression at four hours post exposure to HIV-1, of which many relate to important signaling pathways, such as innate immune responses, pattern recognition receptors, apoptosis, biosynthesis, and energy production, 2) HIV-1 increases the expression of CXC Chemokines (IL-8, CXCL1 and CXCL3) in cervical epithelial cells. IL-8 and CXCL1 are potent chemotactic for multinuclear neutrophils (MNP), monocytes and a minority of lymphocytes, and CXCL3 is predominant chemotactic for monocytes, 3) HIV-1 increases the expression of key inflammatory enzymes-COX-1 and COX-2. COX-1 is responsible for the production of prostaglandins that are important for homeostatic functions, and COX-2 is a key enzyme to convert arachidonic acid to prostaglandins, key inflammatory mediators, and 4) the increased expression of IL-8 and COX-2 revealed using microarray analysis was mapped into the endocervical epithelial cells of macaques inoculated with inactivated SIV in vivo. Our date lead to a role model of epithelial cells in HIV-1 vaginal transmission, that is the axis of HIV-1, epithelial cells, proinflammatory molecules (IL-8, CXCL1, CXCL3, COX-1 and COX-2), cell recruitment (MNP, monocytes and T cells), and inflammation. This model implies that moderating epithelial proinflammatory response to HIV-1 may be utilized in prevention of HIV vaginal transmission.
