475a HIV-1 Induces Human Beta Defensin Expression in Oral Epithelial Cells and Inhibition of HIV-1 Replication In Vitro M.E. Quinones-Mateu*1, M.M. Lederman2, B. Chakraborty1, Z. Feng2, M.L. Marotta1, B. Jiang2, H.R. Rangel1, J. Weber1, M. Mirza1, K. Medvick2, A. Weinberg2 1Cleveland Clinic Foundation, Cleveland, OH and 2Case Western Reserve University, Cleveland, OH
Background: Mechanisms of resistance to R5 and X4 HIV-1 infection are incompletely understood. In particular, mechanisms underlying the infrequent transmission of HIV-1 through the oral mucosa are simply unknown. Here we evaluated the anti-HIV-1 activity of human beta defensins (hBDs), small cationic innate defense molecules that provide a first protection for mucosal surfaces.
Methods: Normal human oral epithelial cell (NHOEC) monolayers were challenged with four different HIV-1 strains (i.e., SI/X4, HXB2 and NL4-3; NSI/R5, 93US142 and 92US660). Afterward, human beta defensin (hBD)-1, -2, and -3 mRNA expression was measured by conventional (semi-quantitative) and TaqMan real time (quantitative) RT-PCR. Two HIV-1 isolates (i.e., SI/X4 HXB2 and NSI/R5 93US142) were incubated with increasing concentrations (5-40 mg/ml) of hBD-1, -2, and -3, and were tested for their ability to infect GHOST CCR5/CXCR4 cells. Fluorescence microscopy and viral reverse transcriptase activity were used to measure HIV-1 replication. CEM cells were incubated with hBDs and surface expression of CXCR4 was measured by confocal fluorescence microscopy.
Results: Although HIV-1 infection was not detected in NHOECs, HIV-1 strains from both viral phenotypes induced 10-to-100-fold expression of hBD2 mRNA, but not hBD-1 nor -3 in these cells. While hBD-1 had not antiviral activity, both hBD-2 and hBD-3 showed a concentration-dependent inhibition of HIV-1 infectivity (up to 75% inhibition) without cellular citotoxicity. This antiretroviral effect was significantly greater against the SI/X4 HXB2 strain than against the NSI/R5 93US142 isolate. In addition to a direct and irreversible effect on virion infectivity, hBD-2 binding also induced decreased surface expression of the HIV-1 coreceptor CXCR4 on CEM cells.
Conclusions: HIV-1 induces beta defensin expression in oral epithelial cells and beta defensins block HIV-1 replication via both a direct interaction with virions and also via modulation of the CXCR4 coreceptor. Beta defensins may provide mucosal protection against HIV-1 transmission as well as against other pathogens.
