17-β-estradiol enhances neutrophil extracellular trap formation by interaction with estrogen membrane receptor

Cell death-associated neutrophil extracellular trap formation (NETosis) occurs during various autoimmune diseases including systemic lupus erythematosus and rheumatoid arthritis, as well as during gestation. Although increasing estrogen concentrations associated with pregnancy might induce NETosis via nuclear estrogen receptor (ER alpha/ER beta), little is known about the mechanisms associated with estrogen-induced NETosis. Here, we investigated the effects of estrogen (17-beta-estradiol; E2) on NETosis, focusing on mechanisms associated with estrogen membrane receptor (GPR30) in neutrophil-like HL-60 cells. Our results show that E2 and the GPR30 agonist G-1 increases level of NETosis and NET formation. Moreover, NETosis-associated intracellular and extracellular histone citrullination and peptidyl arginine deiminase 4 (PAD4) expression were also increased by E2 or G-1 treatment. Furthermore, GPR30 antagonist pre-treatment inhibited increases in NETosis and PAD4 expression mediated by G-1 and partially inhibited these effects mediated by E2. These results demonstrate that E2 treatment induces NETosis via not only ER alpha/ER beta but also GPR30 in neutrophil-like HL-60 cells.