Hydrogen peroxide signals E. coli phagocytosis by human polymorphonuclear cells; up-stream and down-stream pathway

Abstract

Hydrogen peroxide (Η2Ο2) is produced during a variety of cellular procedures. In this paper, the regulatory role of Η2Ο2, in Escherichia coli phagocytosis by the human polymorphonuclears, was investigated. White blood cells were incubated with dihydrorhodamine (DHR) in order to study H2O2 synthesis and E. coli-FITC to study phagocytosis. Flow cytometry revealed increased synthesis of H2O2 in polymorphonuclears which incorporated E. coli-FITC. The blocking of H2O2 synthesis by specific inhibitors, N-ethylmaleimide (ΝΕΜ) for NADPH oxidase and diethyldithiocarbamate (DDC) for superoxide dismutase (SOD), decreased E. coli phagocytosis, as well. Immunoblot analysis of white blood cell protein extracts revealed that the blocking of NADPH oxidase and SOD decreased ERK-1/2 phosphorylation, while it had no effect on JNK and p38. Confocal microscopy showed that phosphorylation of MAPKs and phagocytosis solely occur in the polymorphonuclear and not in mononuclear cells. The use of specific MAPKs inhibitors showed that all of them are necessary for phagocytosis, but only phospho-p38 affects H2O2 synthesis. The blocking of JNK phosphorylation, in the presence of E. coli, evoked a further decrease of cytoplasmic p47 thus increasing its translocation onto the plasma membrane for the assembly of NADPH oxidase. It appears that newly synthesised H2O2 invigorates the phosphorylation and action of ERK-1/2 in E. coli phagocytosis, while phospho-JNK and phospho-p38 appear to regulate H2O2 production.

LETMD1 Regulates Phagocytosis and Inflammatory Responses to Lipopolysaccharide via Reactive Oxygen Species Generation and NF-κB Activation in Macrophages

“…ROS is involved in MyD88-dependent NF-kB activation to induce IL-6 expression (31). Furthermore, ROS stimulates ERK activation to promote phagocytosis (32) and migration (33,34). Thus, we postulated that ROS is a key factor to explain phenotypes associated with LETMD1 attenuation.…”

Behçet's Syndrome as a Model of Thrombo-Inflammation: The Role of Neutrophils

“…At intracellular level, specific enzymes, the mitogen-activated protein kinases (MAPK), are responsive to ROS in a cell type- and stimulus-specific manner (39). Endogenous H 2 O 2 production by neutrophils is tightly regulated by p38-MAPK and c-Jun n-terminal kinase (JNK) and is responsible for ERK1/2 phosphorylation (40).…”

MK2 Is Required for Neutrophil-Derived ROS Production and Inflammatory Bowel Disease

“…The MAPK family of signaling pathways, consisting of the extracellular signal-regulated kinases (ERKs), Jun N-terminal kinases (JNKs), p38 kinase, ERK3/4, and BMK1 pathways, has interaction with ROS (46). The production of ROS was regulated by JNK and p38 MAPK and ROS, in turn, could induce phosphorylation of ERK1/2 in neutrophils (47). The oxidative stress also could activate p38 MAPK, JNK, and BMK1 signals (46).…”