Session 82Poster Presentations Microbicides Session Day and Time: Tuesday 1:30 - 3:30 pm Room: Hall A
673 R5 HIV Infection of Langerhans Cells within Epithelial Tissue Explants Is Regulated by Compound CCR5 Polymorphisms and Is Blocked by Chemically Modified RANTES Analogues B T. Kawamura1, O. Hartley2, F. O. Gulden3, D. T. McNamara3, D. L. Borris1, M. M. Lederman3, R. E. Offord2, P. A. Zimmerman3, A. Blauvelt*1 1Natl Cancer Inst, Bethesda, MD; 2Univ of Geneva, Switzerland; and 3Case Western Reserve Univ, Cleveland, OH
Background: Langerhans cells (LC) are suspected to be initial targets for HIV following sexual exposure (by becoming infected or by capturing virus). To model these biologic events, we recently reported that LC within epithelial tissue explants could be preferentially infected with R5 HIV isolates.
Method: Here, we show that R5 HIV infection of LC ex vivo and LC-mediated transmission of virus to CD4+ T-cells were both dependent upon CD4/CCR5 and independent of C-type lectin-mediated capture of virus. By contrast, infection of monocyte-derived dendritic cells (mDC) and transfer of infection from mDC to CD4+ T-cells were mediated by both CCR5-dependent and DC-SIGN-dependent pathways. Furthermore, in 62 healthy individuals, R5 HIV infection levels in LC ex vivo correlated with CCR5 genotype. Specifically, genotyping for ORFD32 revealed that LC isolated from ORFD32/wt individuals were significantly less susceptible to HIV when compared to LC isolated from ORFwt/wt individuals. Strikingly, further genetic analyses of the A-2459G CCR5 promoter polymorphism in ORFD32/wt heterozygous individuals revealed that LC isolated from .2459A/G + ORFD32/wt individuals were markedly less susceptible to HIV than were LC from .2459A/A + ORFD32/wt individuals. Interestingly, these genetic susceptibility data in LC parallel those of genetic studies performed in cohorts of HIV-infected individuals. Lastly, to determine the most potent inhibitor of HIV infection in LC, we directly compared blocking ability of 4 chemically modified chemokines that bind CCR5 (AOP-RANTES, NNY-RANTES, PSC-RANTES, UCB-RANTES) using our explant model.
Results: All analogues blocked R5 HIV in a dose-dependent manner (1-100 nM) when pre-incubated with explant tissue for 20 mins prior to HIV exposure. In addition, all analogues could inhibit LC-mediated HIV infection of CD4+ T-cells that were co-cultured with LC. The newer analogues (PSC-RANTES and UCB-RANTES) performed at least 10-fold better than AOP-RANTES.
Conclusions: In conclusion, CCR5-mediated infection of LC, and not capture of virus by LC, provides a biologic basis for understanding certain aspects of host genetic susceptibility to initial HIV infection, as well as providing an attractive target for microbicides designed to block sexual transmission of HIV.
