Some ANG II receptor type 1 (AT(1)) antagonists are reported to inhibit proinflammatory cytokine production in vitro and in vivo. However, the effects of the drugs on autoimmune diseases are unknown. We tested the hypothesis that olmesartan, a novel AT(1) antagonist, ameliorated experimental autoimmune myocarditis (EAM) in rats attributed to the suppression of inflammatory cytokines as well as to the immunomodulatory action of the heart. We administered olmesartan orally at does of 1, 3, and 10 mg.kg(-1).day(-1) to rats with EAM for 3 wk. The results showed that olmesartan decreased blood pressure significantly compared with the untreated group and markedly reduced the severity of myocarditis associated with the decrease of myocardial macrophage, CD4(+), and CD8(+) T-cell expression by comparison of heart wt-to-body wt ratios, pericardial effusion scores, and macroscopic and microscopic scores. Numbers of myocardial interleukin-1beta (IL-1beta)-positive-staining cells (obtained by immunohistochemistry) and quantities of IL-1beta expression (obtained by Western blotting) were significantly lower in rats with EAM given olmesartan treatment compared with rats given vehicle. Cardiac myosin-specific, delayed-type hypersensitivity was significantly lower in olmesartan-treated rats than in control rats. The cytotoxic activities of lymphocytes in rats with EAM treated with olmesartan were reduced compared with untreated control rats. In vitro study showed that both olmesartan and its active metabolite RNH-6270 suppressed IL-1beta production in U-937 cells and cultured myocytes. Olmesartan ameliorates acute EAM in rats. The cardioprotection of olmesartan may be due to suppression of inflammatory cytokines as well as to suppressive effects of cytotoxic myocardial injury in addition to hemodynamic modifications.
In this study, we tested the hypothesis that MCI-186 (3-methyl-1-phenyl-2-pyrazolin-5-one; edaravone), a novel free radical scavenger, protects against acute experimental autoimmune myocarditis (EAM) in rats by the radical scavenging action associated with the suppression of cytotoxic myocardial injury. Recent evidence suggests that oxidative stress may play a role in myocarditis. We administered MCI-186 intraperitoneally at 1, 3, and 10 mg ⅐ kg Ϫ1 ⅐ day Ϫ1 to rats with EAM for 3 wk. The results were compared with untreated rats with EAM. MCI-186 treatment did not affect hemodynamics. MCI-186 treatment (3 and 10 mg ⅐ kg Ϫ1 ⅐ day Ϫ1 ) reduced the severity of myocarditis as assessed by comparing the heart-to-body weight ratio and pathological scores. Myocardial interleukin-1 (IL-1)-positive cells and myocardial oxidative stress overload with DNA damage in rats with EAM given MCI-186 treatment were significantly less compared with those of the untreated rats with EAM. In addition, MCI-186 treatment decreased not only the myocardial protein carbonyl contents but also the myocardial thiobarbituric acid reactive substance products in rats with EAM. The formation of hydroxyl radicals in MCI-186-treated heart homogenates was decreased compared with untreated heart homogenates. Furthermore, cytotoxic activities of lymphocytes of rats with EAM treated with MCI-186 were significantly lower compared with those of the untreated rats with EAM. Hydroxyl radicals may be involved in the development of myocarditis. MCI-186 protects against acute EAM in rats associated with scavenging hydroxyl free radicals, resulting in the suppression of autoimmune-mediated myocardial damage associated with reduced oxidative stress state. lymphocytes; immune system; inflammation IN PATIENTS WITH HEART FAILURE, reactive oxygen species (ROS) have been found to be elevated in plasma (2). Acute myocarditis is a potentially lethal disease and frequently precedes the development of acute and chronic heart failure. Two mechanisms to explain how myocarditis develops into heart failure have been proposed: one is a persistent viral or etiologic agent infection, and the other is a progressive autoimmune myocardial injury. The autoimmune giant cell myocarditis in rats mimics human fulminant myocarditis with heart failure (12).Excess amount of cytokine induced by inflammatory stimuli contributes to the progression of myocardial damage in myocarditis (1,5,7,15,16,22,23). Also, recent reports indicated that myocardial injury was produced by ROS (18,19,29). Lipid peroxidation is also caused by ROS (20), resulting in cell membrane damage. As proposed, MCI-186 (3-methyl-1-phenyl-2-pyrazolin-5-one; edaravone) is a novel free radical scavenger (8, 27, 28) and may be an effective agent for myocardial inflammation by inhibiting overproduced cytokines (24). The purpose of the present study was to examine the effects of MCI-186 on experimental autoimmune myocarditis (EAM), focusing on its inhibitory effects on the inflammatory cytokines and on free radical generation...
Excess amount of cytokine produced by inflammatory stimuli contributes to the progression of myocardial damage in myocarditis. Some angiotensin II receptor type 1 antagonists are reported to inhibit proinflammatory cytokine production in vitro and in vivo. We tested the hypothesis that olmesartan, a novel angiotensin II receptor type 1 antagonist, ameliorated experimental autoimmune myocarditis (EAM) in rats attributing to the suppression of inflammatory cytokines in the heart. We orally administered olmesartan 1, 3, and 10 mg/kg/day to rats with EAM for 3 weeks. The results showed that olmesartan decreased blood pressure significantly compared with the untreated group, but markedly reduced the severity of myocarditis by comparing the heart weight/body weight ratio, pericardial effusion scores, macroscopic scores and microscopic scores. Myocardial interleukin (IL)- 1beta expression by western blotting and IL-1beta-positive staining cells by immunohistochemistry were significantly lower in rats with EAM given olmesartan treatment compared with those of rats given vehicle. We conclude that Olmesartan ameliorates acute EAM in rats. The cardioprotection of olmesartan may be due to suppression of inflammatory cytokines dependent of the hemodynamic modifications.
We investigated whether carvedilol protects against experimental autoimmune myocarditis (EAM) attributing to antioxidant properties. Acute EAM was induced by porcine cardiac myosin in Lewis rats. We orally administered a vehicle, various dosages of carvedilol, metoprolol, or propranolol to rats with EAM for 3 weeks. Three beta-blockers decreased heart rates to the same extent. Carvedilol, but not metoprolol or propranolol, markedly reduced the severity of myocarditis at the two different dosages. Only carvedilol decreased the myocardial protein carbonyl contents, and also decreased the myocardial thiobarbituric acid reactive substance products in rats with EAM. Accordingly, carvedilol protects against acute EAM in rats, and this superior cardioprotective effect of carvedilol to metoprolol and propranolol may be due to the antioxidant properties in addition to the hemodynamic modifications.
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