Chemokine receptor expression by human syncytiotrophoblast--a review

Knowledge of chemokine receptor expression by human syncytiotrophoblast has important implications for our understanding of maternal-fetal HIV transmission as well as for understanding the regulation of placental growth and development. This review discusses what is known about chemokine receptor expression by trophoblast and other placental cells. In addition, new data are presented showing that CXCR4 is expressed on the syncytiotrophoblast surface. In other new studies, leukocyte-mediated HIV-1Lai(an X4 strain) infection of syncytiotrophoblast cultures was reduced when stromal derived factor-1alpha was added to the cocultures, consistent with a role for CXCR4. The available information on chemokine receptor expression by trophoblast is discussed in terms of the apparent selective transmission of R5 strains. Studies in other systems indicate that caution must be used in predicting chemokine receptor usage by different HIV isolates, particularly when the route of infection is cellmediated.