NFkappaB is persistently activated in continuously stimulated human neutrophils.
Increased activation of the transcription factor NFkappaB in the neutrophils has been associated with the pathogenesis of sepsis, acute lung injury (ALI), bronchopulmonary dysplasia (BPD), and other neutrophil-mediated inflammatory disorders. Despite recent progress in analyzing early NFkappaB activation in human neutrophils, activation of NFkappaB in persistently stimulated neutrophils has not been previously studied. Because it is the persistent NFkappaB activation that is thought to be involved in the host response to sepsis and the pathogenesis of ALI and BPD, we hypothesized that continuously stimulated human neutrophils may exhibit a late phase of NFkappaB activity. The goal of this study was to analyze the NFkappaB activation and expression of IkappaB and NFkappaB proteins during neutrophil stimulation with inflammatory signals for prolonged times. We demonstrate that neutrophil stimulation with lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNFalpha) induces, in addition to the early activation at 30-60 min, a previously unrecognized late phase of NFkappaB activation. In LPS-stimulated neutrophils, this NFkappaB activity typically had a biphasic character, whereas TNFalpha-stimulated neutrophils exhibited a continuous NFkappaB activity peaking around 9 h after stimulation. In contrast to the early NFkappaB activation that inversely correlates to the nuclear levels of IkappaBalpha, however, in continuously stimulated neutrophils, NFkappaB is persistently activated despite considerable levels of IkappaBalpha present in the nucleus. Our data suggest that NFkappaB is persistently activated in human neutrophils during neutrophil-mediated inflammatory disorders, and this persistent NFkappaB activity may represent one of the underlying mechanisms for the continuous production of proinflammatory mediators.
Miskolci
Veronika
V
Department of Biological Sciences, St. John's University, New York, NY 11439, and Center for Immunology and Inflammation, The Feinstein Institute for Medical Research, North Shore--Long Island Jewish Health System, New Hyde Park, NY, USA.
Rollins
Janet
J
Vu
Hai Yen
HY
Ghosh
Chandra C
CC
Davidson
Dennis
D
Vancurova
Ivana
I
D000328:Adult; D002478:Cells, Cultured; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism*; D018375:Neutrophil Activation / Q000187:drug effects / Q000502:physiology; D009504:Neutrophils / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D008070:Lipopolysaccharides; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha