Decidual lymphatic endothelial cell-derived granulocyte-macrophage colony-stimulating factor induces M1 macrophage polarization via the NF-& kappa;B pathway in severe pre-eclampsia

ProblemDirect interactions between macrophages and lymphatic vessels have been shown previously. In pre-eclampsia (PE), macrophages are dominantly polarized into a proinflammatory M1 phenotype and lymphangiogenesis is defective in the decidua. Here, we investigated whether decidual lymphatic endothelial cells (dLECs) affect macrophage polarization in PE. Method of StudyTHP-1 macrophages were cocultured with dLECs or cultured in the conditioned medium (CM) of dLECs. Macrophage polarization was measured using flow cytometry. Granulocyte-macrophage colony-stimulating factor (GM-CSF) expression in dLECs was measured using qRT-PCR and ELISA. The activation of nuclear translocation of nuclear factor-& kappa; (NF-& kappa;B), an upstream signaling molecule of GM-CSF, was assessed by immunocytochemical localization of p65. Through GM-CSF knockdown and NF-& kappa;B inhibition in dLEC, we evaluated whether the GM-CSF/NF-& kappa;B pathway of PE dLEC affects decidual macrophage polarization. ResultsThe ratio of inflammatory M1 macrophages with HLA-DR+/CD80(+) markers significantly increased following coculturing with PE dLECs or culturing in PE dLEC CM, indicating that the PE dLEC-derived soluble factor acts in a paracrine manner. GM-CSF expression was significantly upregulated in PE dLECs. Recombinant human GM-CSF induced macrophage polarization toward an M1-like phenotype, whereas its knockdown in PE dLECs suppressed it, suggesting PE dLECs induce M1 macrophage polarization by secreting GM-CSF. The NF-& kappa;B p65 significantly increased in PE dLECs compared to the control, and pretreatment with an NF-& kappa;B inhibitor significantly suppressed GM-CSF production from PE dLECs. ConclusionsIn PE, dLECs expressing high levels of GM-CSF via the NF-& kappa;B-dependent pathway play a role in inducing decidual M1 macrophage polarization.