Pseudomonas pyocyanin stimulates IL-8 expression through MAPK and NF-κB pathways in differentiated U937 cells

Abstract

BackgroundPyocyanin (PCN), an extracellular product of Pseudomonas aeruginosa and a blue redox active secondary metabolite, plays an important role in invasive pulmonary infection. However, the detailed inflammatory response triggered by PCN infection in inflammatory cells (particularly macrophages), if present, remains to be clarified. To investigate the effects of PCN on macrophages, the ability of PCN to induce inflammation reaction and the signaling pathway for IL-8 release in PCN-induced differentiated U937 cells were examined.ResultsIt was found that PCN increased IL-8 release and mRNA expression in Phorbol 12-myristate 13-acetate (PMA) differentiated U937 cells in both a concentration- and time-dependent manner by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). P38 and ERK MAPKs were activated after 10 min of induction with PCN and their levels returned to baselines after 30 min by Western blotting. It was also found that within 10 min of PCN incubation, the level of p-I-κBα in the cytosol was increased, which returned to baseline level after 60 min. Meanwhile, the level of p-p65 was increased in the nuclear extract and cytosol, and maintained high in total cell lysates. The results were further confirmed by the observation that p38, ERK1/2 and NF-κB inhibitors inhibited PCN-induced NF-κB activation and attenuated PCN-induced IL-8 expression in U937 cells as a function of their concentrations. Moreover, it was shown that PCN induced oxidative stress in U937 cells and N-acetyl cysteine, an antioxidant, was able to inhibit PCN-induced IL-8 protein expression.ConclusionsIt is concluded that PCN induces IL-8 secretion and mRNA expression in PMA-differentiated U937 cells in a concentration- and time- dependent manner. Furthermore, p38 and ERK MAPKs and NF-κΒ signaling pathways may be involved in the expression of IL-8 in PCN-incubated PMA-differentiated U937 cells.

Pseudomonas aeruginosa infection stimulates mitogen‐activated protein kinases signaling pathway in human megakaryocytes

“…In megakaryocytes, the p38 MAPK pathway has been shown to be essential for megakaryocyte rupture‐dependent thrombopoiesis, which increases platelet production . In addition, activation of the p38 MAPK pathway results in further activation of NF‐κB and release of anti‐inflammatory cytokines to recruit neutrophils at the site of infection . Our finding of PAO1‐induced p38 activation in Mo7e cells suggests that megakaryocytes undergoes cytotoxicity by modulating signaling pathways in a similar manner to that of other immune effector cells reported so far.…”

“…Innate cells respond to bacterial infection and modulate signaling mechanisms through recognition of bacterial components by their receptors. In most of the earlier studies, surface antigens (i.e., LPS and flagellin) and secretary virulence factors (i.e., pyocyanin and alkaline protease) of P. aeruginosa were found to activate the p38 pathway, resulting in secretion of pro‐inflammatory cytokine such as TNF‐α, IL‐6 and IL‐8 . Our observation that PAO1 lysate induces p38 activation may indicate recognition of any of these secretary virulence factors by Mo7e cells; this possibility requires further study.…”

Modulation of inflammatory response of wounds by antimicrobial photodynamic therapy

“…However, with increase in wound healing time point, loss of viability of P.aeruginosa, and inactivation of its virulent factors possibly led to significant down regulation of NF-kB and inflammatory cytokines. It has been shown that virulent factors secreted by P.aeruginosa such as LPS, phospholipase, proteolytic enzymes and pyocyanin induce damage to fibroblast, endothelial cells in the wound milieu and delay the wound healing [4][5][6]31) . Also, a prolonged inflammatory phase induced by infection, causes increased levels of proteases which destroy components of the extracellular matrix and damage the growth factors 31) .…”

“…Management of infections caused by P. aeruginosa is difficult due to the rapid emergence of multi-antibiotic resistant strains. Further, the toxins and cell components of these bacteria such as lipopolysaccharide (LPS) can induce overproduction of local proinflammatory mediators, casue cell death [3][4][5][6][7][8][9] . Proteases produced by these bacteria also degrade host matrix proteins, thereby impairing host tissue integrity [10][11][12] .…”

Quorum Quenching Potentials of Probiotic Enterococcus Durans Lab38 Against Methicillin Resistant Staphylococcus Aureus

“…Pyocyanin is a blue phenazine redox active secondary metabolite of PA causes adverse invasive pulmonary infection by inhibiting the ciliary function, epidermal cell growth and prostacyclin release [33]. In the presence of 50 µg/ml of EA extract, 19.3±1.2% of pyocyanin production has inhibited.…”