Murine ectoplacental cone-derived trophoblast cells express chemokine receptors

Chemokine receptors (CCRs) have been shown to regulate T cell migration and differentiation as well as the establishment of Th1/Th2 bias. Furthermore, T cells and T cell products are essential to trophoblast development. Thus, postulating that chemokines as well as their receptors may be expressed by trophoblast to move T cells into an interaction with the feto-placental unit, we examined whether CCRs are expressed during the early stages of ectoplacental cone (EPC) formation. For this, murine EPC-derived trophoblast were examined for their ability to express CCRs constitutively or inducible by interferon-gamma (IFN-gamma). Immunofluorescence experiments on EPC-derived trophoblast cells showed that CCR3, CXCR4 and CCR5 are significantly expressed. IFN-gamma accelerated the mobilization of intracellular pools of CCR molecules during early cell culture periods (2-6 h) and, in most cases, increased their expression on EPC-derived trophoblast cells. CCR activity could be detected in the culture supernatants of these cells, inversely proportional to cell surface expression, suggesting the existence of rapid endocytosis and recycling mechanisms. This finding indicates that the level of intracellular CCRs may partly be determined in the extracellular matrix, an event that could play an important role towards neutralization of specific T cell/trophoblast interactions during early stages of pregnancy and protect the fetus against harmful maternal immune responses.