Cytokines, proteases, and ligands of receptor for advanced glycation endproducts (RAGE) released by primary trophoblasts from human term placenta under hypoxic stimulation

Aim: In the placenta, hypoxia followed by reoxygenation (ischemia and reperfusion) is regarded as a trigger for the pathological onset of preeclampsia. In this study, we isolated primary trophoblasts from human term placenta, exposed them to hypoxic stress, and measured subsequent levels of cytokines, proteases, protease inhibitors, and ligands of receptor for advanced glycation endproducts (RAGE) to identify the trigger molecule released from hypoxic placenta into maternal circulation. Methods: Ten placental samples were taken from healthy elective caesarean section patients. Trophoblasts were isolated using a Percoll-based method and cultured under 20% oxygen with or without 3 rounds of 0.1% hypoxic stimulation for 1 h. Results: Cell viability did not differ between normal and hypoxic cultures (MTT assay), but cell injury was attenuated in hypoxic culture (LDH assay). In cell culture supernatants, concentrations of MMP-2, TIMP-2, IL-6, and IL-10 decreased in hypoxia compared to normal culture, while the RAGE ligand HMGB1 increased significantly in hypoxic culture. There were no significant differences in concentrations of MMP-9, TIMP-1, IL-8, or S100A12. Conclusions: These results suggest that human term placenta under hypoxia and reperfusion releases the RAGE ligand HMGB1, a “danger signal”, that can trigger systemic inflammation and lead to preeclampsia or placenta-based complications in pregnancy.