INVOLVEMENT OF MITOGEN-ACTIVATED PROTEIN KINASES P38 AND ERK1/2 AS WELL AS PROTEIN KINASE B AKT1/2 IN THE FORMATION OF NEUTROPHIL EXTRACELLULAR TRAPS

Abstract

Neutrophils release decondensed nuclear chromatin or Neutrophil Extracellular Traps (NETs) in response to a great number of physiological stimuli to protect the host from pathogens. However, NETs have recently been shown to play an important role in the pathogenesis of autoimmune, infl ammatory, and malignant diseases. Therefore, understanding the molecular mechanisms underlying NETs formation, usually leading to the neutrophil death (NETosis), is extremely important to control the aberrant release of chromatin. Mitogen-activated protein kinases (MAP-kinases) are involved in various cellular functions such as oxidative burst, chemotaxis, degranulation, adhesion, and apoptosis, but their role in NETosis is not well understood. Three families of MAP-kinases, p38, ERK1/2, and JNK, have been described in human neutrophils, and we investigated the contribution of p38, ERK1/2, and protein kinase B Akt1/2 in oxidative burst and NETosis using inhibitory analysis. We have shown that MAPkinase p38 as well as protein kinase B Akt1/2 are activated upon stimulation of oxidative burst and NETosis with calcium ionophore ionomycin. However, these kinases are not involved in the oxidative burst induced by diacylglycerol mimetic phorbol 12-myristate 13-acetate (PMA) but are involved in PMA-induced NETosis.