Interleukin-18 stimulates fibronectin expression in primary human cardiac fibroblasts via PI3K-Akt-dependent NF-kappaB activation.
Fibronectin (FN), a key component of the extracellular matrix, is upregulated in cardiac tissue during myocardial hypertrophy and failure. Here we show that interleukin (IL)-18, a proinflammatory and pro-hypertrophic cytokine, stimulates FN expression in adult human cardiac fibroblasts (HCF), an effect blocked by either the IL-18BP:Fc chimera or IL-18 neutralizing antibodies. IL-18 stimulated FN promoter-reporter activity in HCF, a response attenuated by mutation of an NF-kappaB binding site in the FN promoter. Overexpression of p65 stimulated FN transcription. IL-18 stimulated in vitro (p65, p50) and in vivo NF-kappaB DNA binding activities, and induced kappaB-dependent reporter gene activity. These effects were inhibited by adenoviral transduction of dominant negative (dn) p65 (Ad.dnp65) and dnIKK2 (Ad.dnIKK2). Investigation of signaling intermediates revealed that IL-18 stimulated PI3 kinase activity (blocked by wortmannin, LY294002, or Ad.dnPI3Kp85), and Akt phosphorylation and kinase activity (blocked by SH-5 or Ad.dnAkt). Furthermore, targeting MyD88, IRAK1, TRAF6, PI3K, Akt, and NF-kappaB by RNA interference or dn expression vectors blunted IL-18 mediated FN transcription and mRNA expression. Conversely, FN stimulated IL-18 expression. These data provide the first evidence that IL-18 and FN stimulate each other's expression in HCF, and suggest a role for IL-18, FN and their crosstalk in myocardial hypertrophy and remodeling, disease states characterized by enhanced FN expression and fibrosis.
Department of Surgery, University of Texas Health Science Center, San Antonio, Texas, USA.
Venkatapuram Seenu
VS
Reddy
Ralf Egan
RE
Harskamp
Margreet Willie
MW
van Ginkel
John
J
Calhoon
Clinton Eugene
CE
Baisden
In-San
IS
Kim
Anthony J
AJ
Valente
Bysani
B
Chandrasekar
D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D053592:Interleukin-1 Receptor-Associated Kinases / Q000378:metabolism; D020382:Interleukin-18 / Q000378:metabolism / Q000494:pharmacology*; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D009206:Myocardium / Q000166:cytology* / Q000201:enzymology; D016328:NF-kappa B / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012995:Solubility / Q000187:drug effects; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D016207:Cytokines; D005353:Fibronectins; D018836:Inflammation Mediators; D036341:Intercellular Signaling Peptides and Proteins; D020382:Interleukin-18; D053594:Myeloid Differentiation Factor 88; D016328:NF-kappa B; D012333:RNA, Messenger; D048029:TNF Receptor-Associated Factor 6; D019869:Phosphatidylinositol 3-Kinases; C507768:IRAK1 protein, human; D053592:Interleukin-1 Receptor-Associated Kinases; D051057:Proto-Oncogene Proteins c-akt; D051550:I-kappa B Kinase