Fig. 3

Excretory/secretory products suppress the production of NETs due to the decrease in the generation of ROS. a Neutrophils were untreated or pre-treated with various concentrations of ESP (added ATA) (2, 5, 10 ng/μl) for 1 h at 37 °C, followed by stimulation with PMA (100 nM) for 3 h at 37 °C. LDH released from damaged cells is normalized to the total LDH content of an equivalent number of neutrophils lysed with detergent (complete lysis). LDH levels were significantly lower in the ESP-pretreated group compared to the PMA-stimulated group. The white column represents complete lysis (100%) of neutrophils with cell lysis buffer, while the black column indicates untreated neutrophils. ***P < 0.001. b Neutrophils pre-treated with different concentrations of ESP (added ATA) (1, 2, 5, 10 ng/μl, 1 h, 37 °C) prior to PMA activation (100 nM, 3 h, 37 °C). ROS production in neutrophils was measured by the luminol-amplified chemiluminescence method. ROS levels were significantly reduced in ESP-treated neutrophils compared with the PMA-stimulated group. All data are expressed as mean (± standard error mean, SEM) (N for both experimental and control groups = 5); *P < 0.05; ***P < 0.001. ESP, excretory/secretory products; ATA, aurintricarboxylic acid; PMA, phorbol-12-myristate-13-acetate. LDH, lactate dehydrogenase; NETs, neutrophil extracellular traps; ROS, reactive oxygen species