Role of p38 MAPK in PMA‐induced NETs release from human neutrophils

Abstract

Neutrophil extracellular traps (NETs) are produced by the neutrophils to bind and kill the extracellular microorganisms. It is composed of chromatin decorated with granular proteins such as elastase, myeloperoxidase, cathepsin G, pentraxin, lactoferrin etc. In the present study we have investigated the role of p38 MAPK in PMA induced reactive oxygen species (ROS) generation and NETs formation. Human neutrophils treated with PMA induced free radical generation and NETs release in a time (1–3 hrs.) and concentration (10 – 50 nM) dependent manner as demonstrated by DCF response and elastase/DNA release respectively. Since NETs release is dependent on free radicals effect of SB 202190 (50 μM, p38MAPK inhibitor) was investigated on PMA induced free radical formation as assessed by DCF and NBT, which was not significantly reduced. NETs formation was however inhibited by SB 202190 or DPI (10 μM, NADPH oxidase inhibitor), suggesting that p38 MAPK play a role downstream to the NADPH oxidase in PMA induced NETs release. NETs are made up of DNA and elastase, their release was also inhibited by DPI and SB 202190. PMA treatment induced the phosphorylation of p38 MAPK, which was inhibited by DPI. The results of the present study suggest that PMA induced NETs formation was mediated through the activation of NADPH oxidase and p38 MAPK.