Expression of the HIV-1 co-receptors CCR5 and CXCR4 on placental macrophages and the effect of IL-10 on their expression

The chemokine receptors CCR5 and CXCR4 play a key role in HIV-1 infection a s co-receptors for viral entry. In the placenta, an important natural barri er to HIV, the expression and regulation of these receptors has yet to be e lucidated. In this study, ae determined the expression of CCR5 and CXCR4 co -receptors on placental macrophages (Phl) and the effect of interleukin-10 (IL-10) on co-receptor expression. Ph were isolated from term placentae of HIV-uninfected mothers and cultured for up to 11 days. The cells were stimu lated with IL-10 for 24 h and stained with specific antibodies to CCR5, CXC R4, CD4, CD3, CD11c and CD14 for flow cytometry. Unstimulated Phl expressed significantly more CCR5 than CXCR4. Expression of both coreceptors was upr egulated by stimulation with IL-10 at 24 h post-stimulation. In vivo expres sion of these co-receptors from frozen sections revealed a higher percentag e of CCR5 positive cells. This is the first study in which expression of bo th co-receptors is detected on the PR L membrane. These results are consist ent with previous studies performed in our laboratory where PM were readily infected by CCR5-using HIV strains bur could not be productively infected bq; HIV strains that exclusively use CXCR4 as a co-receptor. (C) 2001 IFPA and Harcourt Publishers Ltd.