Overexpressed nuclear factor kappaB correlates with enhanced expression of interleukin-1beta and inducible nitric oxide synthase in aged murine lungs to endotoxic stress.
BACKGROUND
Transcriptional regulation is a major determinant of interleukin-1beta (IL-1beta) protein synthesis. Nuclear factor kappaB (NF-kappaB) plays a central role in the regulation of IL-1beta and subsequent IL-1beta-dependent inflammatory processes. Previously, we observed in a murine endotoxic stress model a progressive increase with age in the amount of IL-1beta mRNA. We test the aging pulmonary response of NF-kappaB and NF-kappaB-dependent genes, IL-1beta, and inducible nitric oxide synthase (iNOS) in the same model.


METHODS
Young (2-month-old) and senescent (25-month-old) mice were given 0.5 mg/kg lipopolysaccharide (LPS) intraperitoneally. Lung and blood samples were harvested after 4 hours. IL-1beta production in blood samples and the expression levels of protein and mRNA of IL-1beta and iNOS in lung tissues were measured. NF-kappaB binding activity in lung tissues was also determined.


RESULTS
LPS induced higher levels of IL-1beta in the sera and lungs of senescent mice over young mice. Northern and Western blot analyses showed that mRNA and protein signals of IL-1beta and iNOS were significantly higher in old lungs than in young lungs. Electrophoretic mobility shift assay also showed that NF-kappaB activation was significantly higher in the older animals.


CONCLUSIONS
Our results suggest that elevated activation of NF-kappaB, at least in part, contributes to the dysregulated expression of IL-1beta and iNOS in the lungs of senescent animals. Thus increased expression of proinflammatory cytokines and inflammatory responsive genes in the lung may play a role in the increased susceptibility in aging animals to endotoxic stress.
Chang
Cheow K
CK
Department of Surgery, Finch University of Health Sciences/The Chicago Medical School at Mount Sinai Hospital Medical Center, Chicago, Illinois, USA.
LoCicero
Joseph
J
D000375:Aging / Q000276:immunology*; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D004731:Endotoxins / Q000494:pharmacology; D004926:Escherichia coli; D007375:Interleukin-1 / Q000096:biosynthesis* / Q000235:genetics; D008070:Lipopolysaccharides; D008168:Lung / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D016328:NF-kappa B / Q000096:biosynthesis / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000032:analysis; D012772:Shock, Septic / Q000276:immunology*; D015533:Transcriptional Activation
D004731:Endotoxins; D007375:Interleukin-1; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse