Ken Kusaba

Inhibition of Progression and Stabilization of Plaques by Postnatal Interferon-γ Function Blocking in ApoE-Knockout Mice

A role of interferon-γ is suggested in early development of atherosclerosis. However, the role of interferon-γ in progression and destabilization of advanced atherosclerotic plaques remains unknown. Thus, the aim of this study was to determine whether postnatal inhibition of interferon-γ signaling could inhibit progression of atherosclerotic plaques and stabilize the lipid- and macrophage-rich advanced plaques. Atherosclerotic plaques were induced in ApoE-knockout (KO) mice by feeding high-fat diet from 8 weeks old (w). Interferon-γ function was postnatally inhibited by repeated gene transfers of a soluble mutant of interferon-γ receptors (sIFNγR), an interferon-γ inhibitory protein, into the thigh muscle every 2 weeks. When sIFNγR treatment was started at 12 w (atherosclerotic stage), sIFNγR not only prevented plaque progression but also stabilized advanced plaques at 16 w: sIFNγR decreased accumulations of the lipid and macrophages and increased fibrotic area with more smooth muscle cells. Moreover, sIFNγR downregulated expressions of proinflammatory cytokines, chemokines, adhesion molecules, and matrix metalloproteinases but upregulated procollagen type I. sIFNγR did not affect serum cholesterol levels. In conclusion, postnatal blocking of interferon-γ function by sIFNγR treatment would be a new strategy to inhibit plaque progression and to stabilize advanced plaques through the antiinflammatory effects.

Roles of Intercellular Adhesion Molecule-1 in Hypertensive Cardiac Remodeling

Abstract—Recently, we have shown that in rats with a suprarenal abdominal aortic constriction (AC), pressure overload induces early perivascular fibro-inflammatory changes (transforming growth factor [TGF]-&bgr; induction and fibroblast proliferation) within the first week after AC and then causes the development of cardiac remodeling (myocyte hypertrophy and reactive myocardial fibrosis) associated with diastolic dysfunction. Intercellular adhesion molecule (ICAM)-1 is implicated in the recruitment of leukocytes, especially macrophages, in various inflammatory situations. Thus, we sought to investigate the causal relation of ICAM-1 to macrophage recruitment and cardiac remodeling in AC rats. In AC rats, immunoreactive ICAM-1 was observed transiently on endothelial cells of the intramyocardial coronary arterioles after day 1, with a peak at day 3, returning to baseline by day 7. Also, ED1+ macrophage accumulation was found in the area adjacent to the arteries expressing ICAM-1. Chronic treatment with an anti–ICAM-1 neutralizing antibody, but not with control IgG, remarkably reduced the accumulations of macrophages and proliferative fibroblasts and inhibited the upregulation of TGF-&bgr; expression. Furthermore, the neutralizing antibody significantly prevented myocardial fibrosis without affecting arterial pressure and left ventricular and myocyte hypertrophy. In conclusion, ICAM-1 expression was induced by pressure overload in the intramyocardial arterioles, and triggered perivascular macrophage accumulation. In pressure-overloaded hearts, a crucial role in ICAM-1–mediated macrophage accumulation was suggested in the development of myocardial fibrosis, through TGF-&bgr; induction and fibroblast activation.

Rho-kinase inhibition reduces neointima formation after vascular injury by enhancing Bax expression and apoptosis.

Summary: Recently, we have shown that a specific Rho‐kinase inhibitor, Y27632 (R‐(+)‐trans‐N‐(4‐pyridyl)‐4‐(1‐aminoethyl)‐ cyclohexanecarboxamide), prevents neointima formation after vascular injury associated with increased terminal deoxynucleotidyl transferase‐mediated dUTP nickend labeling (TUNEL)+ smooth muscle cells. Because the mechanism of the action of Y27632 remains unclear, we investigated the expression changes in Bcl family proteins, apoptosis regulators of smooth muscle cells, in the rat carotid artery after balloon injury (BI). Y27632 (BI + Y group) or saline (BI group) was administered peritoneally from Day 1 to Day 14 after BI. Y27632 markedly prevented neointima formation at Day 14. In the BI group, TUNEL+ smooth muscle cells were transiently increased in the neointima, but not in the media, with a peak at Day 7, returning to a lower level by Day 14. Y27632 significantly increased TUNEL+ smooth muscle cells at Days 7 and 14. Smooth muscle cell apoptosis was confirmed by electron microscopic examination. At Day 14, although proapoptotic Bax was slightly, but not significantly, increased in the BI group, it was significantly upregulated in the BI + Y group. Antiapoptotic Bcl‐xL was upregulated in the BI group, and the upregulated Bcl‐xL was not affected by Y27632. These findings indicate that Rho‐kinase inhibition induces neointimal smooth muscle cell apoptosis through Bax upregulation, resulting in reduced neointima formation.

Inhibition of Intrinsic Interferon-γ Function Prevents Neointima Formation After Balloon Injury

It is still controversial whether intrinsic interferon (IFN)-&ggr; promotes or attenuates vascular remodeling in hyperproliferative vascular disorders, such as neointima formation after balloon injury. Thus, we investigated whether inhibition of intrinsic IFN-&ggr; function prevents neointima formation. For this purpose, naked DNA plasmid encoding a soluble mutant of IFN-&ggr; receptor &agr;-subunit (sIFN&ggr;R; an IFN-&ggr; inhibitory protein) or mock plasmid was injected into the thigh muscle of male Wistar rats 2 days before balloon injury (day −2). sIFN&ggr;R gene transfer significantly elevated serum levels of sIFN&ggr;R protein for 2 weeks. In mock-treated rats, balloon injury induced smooth muscle cell proliferation in the neointima with a peak at day 7 and produced thick neointima at day 14. sIFN&ggr;R treatment reduced the number of proliferating intimal smooth muscle cells by 50% at day 7 and attenuated neointima formation with a 45% reduction of the intima/media area ratio at day 14. In mock-treated rats, at day 7, balloon injury induced phosphorylation of signal transducer and activator of transcription-1 and upregulations of IFN regulatory factor-1 (a transcription factor mediating IFN-&ggr; signal). Balloon injury also upregulated the key molecules of neointima formation, such as intercellular adhesion molecule-1 and platelet-derived growth factor &bgr;-receptor. These changes were suppressed by sIFN&ggr;R treatment. In conclusion, it is suggested that intrinsic IFN-&ggr; promotes neointima formation probably through IFN regulatory factor-1/intercellular adhesion molecule-1–mediated and platelet-derived growth factor–mediated mechanisms. Thus, inhibition of IFN-&ggr; signaling may be a new therapeutic target for prevention of neointima formation of hyperproliferative vascular disorders.

Demonstration of the disease activity by serial carotid artery ultrasonography, magnetic resonance imaging and 18-fluoro-deoxyglucose positron emission tomography in a Behçet's disease patient with carotid artery stenosis

A 24-year-old female with repeated histories for 6 months of genital ulcer, folliculitis, and oral aphthous ulcers discovered a bruit from right side of her neck by herself. Although carotid ultrasonography and three-dimensional computed tomography demonstrated a diffuse thickening of the intima-media complex in the right common carotid artery (CCA) ( Panel A1 …