Resveratrol blocks interleukin-18-EMMPRIN cross-regulation and smooth muscle cell migration

Vascular smooth muscle cell (SMC) migration is an important mechanism in atherogenesis and postangioplasty arterial remodeling. Previously, we demonstrated that the proinflammatory cytokine interleukin (IL)-18 is a potent inducer of SMC migration. Since extracellular matrix metalloproteinase inducer (EMMPRIN) stimulates ECM degradation and facilitates cell migration, we investigated whether IL-18 and EMMPRIN regulate each other's expression, whether their cross talk induces SMC migration, and whether the phytoalexin resveratrol inhibits IL-18-EMMPRIN signaling and SMC migration. Our studies demonstrate that 1) IL-18 induces EMMPRIN mRNA and protein expressions and stimulates EMMPRIN secretion from human aortic SMCs; 2) IL-18 stimulates EMMPRIN expression via oxidative stress and phosphatidylinositol 3-kinase (PI3K)-Akt-ERK signaling; 3) IL-18-stimulated SMC migration is significantly blunted by EMMPRIN knockdown, EMMPRIN function-blocking antibodies, or adenoviral transduction of mutant EMMPRIN; 4) conversely, EMMPRIN stimulates IL-18 expression and secretion via PI3K, Akt, and ERK; and 5) resveratrol attenuates IL-18- and EMMPRIN-mediated PI3K, Akt, and ERK activations; blunts IL-18-mediated oxidative stress; blocks IL-18-EMMPRIN cross-regulation; and inhibits SMC migration. Collectively, our results demonstrate that the coexpression and regulation of IL-18 and EMMPRIN in the vessel wall may amplify the inflammatory cascade and promote atherosclerosis and remodeling. Resveratrol, via its antioxidant and anti-inflammatory properties, has the potential to inhibit the progression of atherosclerosis by blocking IL-18 and EMMPRIN cross-regulation and SMC migration

Interleukin-18 stimulates fibronectin expression in primary human cardiac fibroblasts via PI3K-Akt-dependent NF-κB 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-κB binding site in the FN promoter. Overexpression of p65 stimulated FN transcription. IL-18 stimulated in vitro (p65, p50) and in vivo NF-κB DNA binding activities, and induced κB-dependent reporter gene activity. These effects were inhibited by adenoviral transduction of dominant negative (dn) p65 (Ad.dnp65) and dnlKK2 (Ad.dnlKK2). 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-κB 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

Neutralization of Interleukin-18 Ameliorates Ischemia/Reperfusion-induced Myocardial Injury*

Ischemia/reperfusion (I/R) injury is characterized by the induction of oxidative stress and proinflammatory cytokine expression. Recently demonstrating that oxidative stress and TNF-α each stimulate interleukin (IL)-18 expression in cardiomyocytes, we hypothesized that I/R also induces IL-18 expression and thus exacerbates inflammation and tissue damage. Neutralization of IL-18 signaling should therefore diminish tissue injury following I/R. I/R studies were performed using a chronically instrumented closed chest mouse model. Male C57BL/6 mice underwent 30 min of ischemia by LAD coronary artery ligation followed by various periods of reperfusion. Sham-operated or ischemia-only mice served as controls. A subset of animals was treated with IL-18-neutralizing antibodies 1 h prior to LAD ligation. Ischemic LV tissue was used for analysis. Our results demonstrate that, compared with sham operation and ischemia alone, I/R significantly increased (i) oxidative stress (increased MDA/4-HNE levels), (ii) neutrophil infiltration (increased MPO activity), (iii) NF-κB DNA binding activity (p50, p65), and (iv) increased expression of IL-18Rβ, but not IL-18Rα or IL-18BP transcripts. Administration of IL-18-neutralizing antibodies significantly reduced I/R injury measured by reduced infarct size (versus control IgG). In isolated adult mouse cardiomyocytes, simulated ischemia/reperfusion enhanced oxidative stress and biologically active IL-18 expression via IKK-dependent NF-κB activation. These results indicate that IL-18 plays a critical role in I/R injury and thus represents a promising therapeutic target