Problem: Chemokine receptors of placental trophoblasts possibly act as co-receptors or alternative receptors of maternal fetal infection by HIV. To clarify their possible expression and the physiological roles of chemokines on human placentae, we studied chemokine chemokine receptor expression and the effects of exogenous chemokines on choriocarcinoma cell lines.
Materials and methods: Placental samples were obtained from 13 placentae of various gestational ages. Villous tissue was mechanically dissected from samples. Trophoblasts were enriched by anti-human chorionic gonadotropin (hCG)-coated magnetic beads. Human choriocarcinoma cell lines (JAR, BeWo, JEG-3) were maintained in RPMI 1640 media supplemented with 10% FCS. Expression of chemokine receptors was studied by RT-PCR. The effects of MIP-1alpha, RANTES, MCP-1 on hCG production were estimated by EIA. Effects of chemokines on proliferation of choriocarcinoma cell lines were examined by MTT assay.
Results: We observed mRNA expression of CCR-1, 2, 3, 4, 5 and CXCR-1, 2, 4 in 1st trimester placental villi, CCR-I, 2, 4 and CXCR-1, 2. 4 in 2nd trimester placental villi, CCR-1, 2, 4 and CXCR-4 in 3rd trimester placental villi. Using MACS enriched trophoblasts, we observed identical results. A choriocarcinoma cell line BeWo expressed CCR-1, 3, 4 and CXCR-1, 2, 4 while JEG-3 and JAR expressed CCR-1, 3, 4, 5 and CXCR-1, 2, 4. Expression of the CCR-5 and CXCR-4 protein in choriocarcinoma cell lines and MACS-enriched trophoblats were confirmed by flow cytometry. Chemokine MCP-3, MIP-1alpha, RANTES mRNA were expressed by the 1st, 2nd and 3rd trimester placental samples and the three choriocarcinoma cell lines examined. MCP-1 was expressed by 1st and 2nd trimester placental villi. Administration of chemokines up-regulated proliferation (10(-1) - 10 ng/mL) and hCG production (10(-1) - 10(-2)ng/ mL) of the three choriocarcinoma cell lines examined.
Conclusions: Our results suggest possible roles of chemokines/chemokine receptors on placental physiology and their involvement in HIV transmission as alternative receptors.