P40.31
Background: Majority of human HIV-1 infections are acquired through heterosexual transmission across female genital mucosa. Epithelial cells that line the genital mucosa express toll-like receptors (TLR) and act as first line of defense against mucosal infections. Immune locale orchestrated by TLR mediated activation of female genital epithelial cells can be a critical determinant of HIV-1 resistance or susceptibility. In this study we investigated the role of TLR signaling in female genital epithelial cells in determining the local mucosal cytokine/chemokines milieu.
Methods: Endoervical cytobrsuh samples were obtained from Pumwani CSWs cohort in Nairobi, Kenya. HESN (n=22), HIV− (n=24) and HIV+ (n=23). Cervical epithelial cells (CECs) were purified through a series of nylon membrane filtrations. Purity and viability of CECs was assessed by Ber-EP4 expression and MTS assay, respectively. CECs were cultured with or without TLR3 ligand (poly:IC) or TLR1-9 ligand combined for 24 h. Cytokine/chemokines levels in the supernatants were determined using the Milliplex MAP multiplex kit (Human Cytokine/Chemokine I and III) and analyzed on the BioPlex-200 according to manufacturer's protocol.
Results: We tested 28 cytokines and chemokines (GM-CSF, IFNa2, IFNgamma, IL-1a, IL-1b, IL-2, IL-6, IL-7, IL-8, IL-10, IL-12 (p40), IL-12(p70), IL-15, IL-17, IP-10, MCP-1, MCP-3, MDC, MIP-1a, MIP-1b, RANTES, Fractalkine, GRO, TNFa, I-TAC, MIG, MIP-3 a, and MIP-3 b). CECs from HESN individuals expressed significantly lower levels of interferon-γ- induced protein 10 (IP-10), IL-8, IL-1 a, MIG, and MIP-3 a upon TLR3 or combined TLR1-9 stimulation compared with CECs from HIV- and HIV+ women. These cytokines and chemokines have important functions in inflammatory and immune cell recruitment.
Conclusions: These results highlight the role of TLR signaling in CECs and support the immune quiescence model of HIV-1 protection, whereby lower target and inflammatory cell recruitment at the genital mucosa reduces HIV-1 target cell numbers in HESN.
