Differential expression of CXCR4 receptor in early and term human placenta.

Chemokines and their receptors play a crucial role in regulation of T-cell migration and differentiation. Recent findings suggest that these proteins can also regulate cell functions such as angiogenesis and proliferation. Besides, CXCR4, a chemokine receptor, is one of the two major co-receptors for entry of the HIV virus during the late stages of HIV infection. We have studied the expression of CXCR4 in early (8-10 weeks) and term human placenta. Immunofluorescence staining and RT-PCR analysis revealed a differential expression of the CXCR4 receptor. Densitometric analysis revealed a two fold higher expression of the CXCR4 mRNA in early as compared to term placenta. This finding suggests that the expression of CXCR4 receptor may be developmentally regulated and its role in the early stages of pregnancy is implicated, when embryogenesis and organogenesis takes place. The fact that only 1-2 per cent of the placental transmission of the HIV virus takes place in the early placenta may also be correlated with our findings, suggesting that CXCR4 may not have a direct role in the transmission of HIV infection in the placenta.