Modulation of human beta-defensin-2 transcription in pulmonary epithelial cells by lipopolysaccharide-stimulated mononuclear phagocytes via proinflammatory cytokine production.
Human beta-defensin (hBD)-2, a cationic antimicrobial peptide primarily induced in epithelial cells in response to inflammatory stimuli, plays an important role in host defense. To elucidate the expression mechanism of hBD-2 in the lung, we investigated the modulation of hBD-2 transcription in pulmonary epithelial cells by mononuclear phagocytes stimulated with LPS. Coculture of A549 pulmonary epithelial cells with Mono-Mac-6 monocytic cells in the presence of Escherichia coli LPS markedly up-regulated hBD-2 promoter activity, whereas A549 alone did not respond to LPS to activate the hBD-2 promoter. Furthermore, IL-1beta and TNF-alpha in the culture supernatants from LPS-stimulated monocytic cells activated the hBD-2 promoter in A549 cells. Of note, IL-1beta was more potent than TNF-alpha in this effect. In addition, a mutation of the NF-kappaB site at -200 (pkappaB1 site) completely abolished this IL-1beta- and TNF-alpha-induced hBD-2 promoter activation, whereas NF-kappaB inhibitors (MG-132 and helenalin) strongly suppressed it. Moreover, electrophoretic mobility shift assay suggested that NF-kappaB, consisting of p65-p50 heterodimer, could bind to the pkappaB1 site in cytokine-stimulated A549 cells. Interestingly, flow cytometric analysis revealed that A549 cells expressed CD14 but lacked Toll-like receptor 4, which may account for the hyporesponsiveness of A549 cells to LPS. Taken together, these results suggest that hBD-2 expression in pulmonary epithelial cells is modulated by NF-kappaB via the actions of IL-1beta and TNF-alpha produced by LPS-stimulated mononuclear phagocytes.
Tsutsumi-Ishii
Yuko
Y
Department of Biochemistry, Juntendo University, School of Medicine, Tokyo, Japan.
Nagaoka
Isao
I
D002460:Cell Line; D016207:Cytokines / Q000096:biosynthesis* / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000276:immunology* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D018836:Inflammation Mediators / Q000494:pharmacology*; D007375:Interleukin-1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000378:metabolism / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000096:biosynthesis; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism; D005810:Multigene Family / Q000276:immunology; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000276:immunology; D011650:Pulmonary Alveoli / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000096:biosynthesis; D020218:Response Elements / Q000276:immunology; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014158:Transcription, Genetic / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000502:physiology; D020298:U937 Cells; D023083:beta-Defensins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism
D016207:Cytokines; C106641:DEFB4A protein, human; D004791:Enzyme Inhibitors; D018836:Inflammation Mediators; D007375:Interleukin-1; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D011956:Receptors, Cell Surface; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha; D023083:beta-Defensins