Interleukin-18/Interleukin-18 Binding Protein Signaling Modulates Atherosclerotic Lesion Development and Stability

Abstract

Abstract-Interleukin (IL)-18 is the interferon-␥-inducing factor and has other proinflammatory properties. The precise role of IL-18 in immunoinflammatory diseases remains poorly understood. In this study, we show that in vivo electrotransfer of an expression-plasmid DNA encoding for murine IL-18 binding protein (BP) (the endogenous inhibitor of IL-18) prevents fatty streak development in the thoracic aorta of apoE knockout mice and slows progression of advanced atherosclerotic plaques in the aortic sinus. More importantly, transfection with the IL-18BP plasmid induces profound changes in plaque composition (decrease in macrophage, T cell, cell death, and lipid content and increase in smooth muscle cell and collagen content) leading to a stable plaque phenotype. These results identify for the first time a critical role for IL-18/IL-18BP regulation in atherosclerosis and suggest a potential role for IL-18 inhibitors in reduction of plaque development/progression and promotion of plaque stability. Key Words: atherosclerosis Ⅲ inflammation Ⅲ interleukin Ⅲ cytokines A therosclerosis is the leading cause of mortality in industrialized countries and carries an important socioeconomic burden. Unabated inflammatory mechanisms are responsible for changes in atherosclerotic plaque composition leading to plaque disruption and to the occurrence of acute ischemic syndromes, namely myocardial infarction and stroke. 1 Interleukin (IL)-18 is an inducer of interferon (IFN)-␥ with potent activities on inflammatory and vascular cells 2 and is thought to contribute to the pathogenesis of chronic immunoinflammatory processes. 3,4 Interestingly, we have recently detected increased production of IL-18 by macrophages and smooth muscle cells in unstable human atherosclerotic plaques that were responsible for strokes compared with stable plaques from asymptomatic patients. 5 An endogenous IL-18 binding protein (IL-18BP) that neutralizes IL-18 has been identified. 6 However, the role of IL-18BP in the modulation of atherogenesis and other chronic immunoinflammatory diseases in vivo is currently unknown. In this study, we examined the role of IL-18/IL-18BP in a wellvalidated model of atherosclerosis. Materials and Methods In Vivo Intramuscular Electrotransfer of Murine IL-18BP Expression PlasmidFourteen male C57BL/6 apoE knockout mice, 14 weeks old, received at 3-week intervals, 3 injections with the murine IL-18BP expression plasmid, pcDNA3-mIL18BP. The control mice (nϭ19) were injected with the control empty plasmid. Murine IL-18BP isoform d cDNA (accessory number #AF110803), isolated as described, 6 was subcloned into the EcoR1/Not1 sites of mammalian cell expression vector pcDNA3 under the control of the cytomegalovirus promotor (Invitrogen). Control vector was a similar construct devoid of therapeutic cDNA. The construct with mIL-18BP isoform d in pCDNA3 plasmid was tested for expression and activity. This was performed using culture supernatants obtained from HEK 293/Ebna cells transfected with mIL-18BPd in pCDNA3 vector. We verified...

Reduction of Pro-Inflammatory Cytokines through Hemodiafiltration

“…[37][38][39] Mallat et al had found that IL-18 binding protein can reduce atherosclerosis. [40] In our study, the plasma IL-18 level was reduced after six months of HDF, which may result in less IL-18 related atherosclerosis.…”

Transplantation of Bone Marrow–Derived Mononuclear Cells in Ischemic Apolipoprotein E–Knockout Mice Accelerates Atherosclerosis Without Altering Plaque Composition

“…Serial sections of the aortic sinus were assayed for lipid deposition and collagen detection (with oil red O and sirius red, respectively; see Figure). 11 Immunohistochemistry was performed with the use of a rat anti-mouse macrophage antibody, clone MOMA-2 (Biosource International), a polyclonal goat anti-CD3⑀ antibody (Santa Cruz), a monoclonal anti-␣-smooth muscle actin, clone 1A4 (Sigma), or a goat polyclonal anti-CD31 antibody (Santa Cruz). Computerized quantifications were performed with the use of Histolab software.…”

Differences in signaling pathways by IL-1β and IL-18

“…The IL-18 receptor (IL-18R) complex consists of two receptor chains: a ligand-binding chain termed the IL-18R␣ chain and a coreceptor termed IL-18R␤ chain; both chains are required for signaling. Using specific neutralization of IL-18 activity, there is a role for IL-18 in rheumatoid arthritis (8,9), ischemic renal (10), and heart disease (11), as well as atherosclerosis (12).…”