Autoimmune Myocarditis In Rats Research Articles

Hydrodynamics-based delivery of an interleukin-1 receptor II fusion gene ameliorates rat autoimmune myocarditis by inhibiting IL-1 and Th17 cell polarization

Type II interleukin-1 receptor (IL-1RII) is a non-signaling decoy receptor that blocks the activity of interleukin-1 (IL-1), a pro-inflammatory cytokine involved in experimental autoimmune myocarditis (EAM). The aim of this study was to examine the effects of hydrodynamics-based delivery of a recombinant plasmid encoding IL-1RII-Ig and to elucidate the role of IL-1RII in EAM rats. Rats were immunized on day 0 and injected with a recombinant plasmid encoding IL-1RII-Ig or pCAGGS-SP-Ig (control plasmid) on day 6. IL-1RII-Ig gene therapy effectively controlled EAM as indicated by a decreased heart weight-to-body weight ratio, reduced areas of myocarditis, reduced expression of genes encoding atrial natriuretic peptide and brain natriuretic peptide in the heart, and improved cardiac function. IL-1RII-Ig significantly inhibited the expression of IL-1-related cytokines such as IL-1β, prostaglandin E2 synthase, cyclooxygenase, and monocyte chemotactic protein-1 in EAM hearts. Furthermore, the effect of serum containing IL-1RII-Ig on the expression of immune-related genes in IL-1-stimulated splenocytes cultured from EAM rats was examined. The results showed that the expression of IL-6, transforming growth factor-β, retinoic acid-related orphan nuclear receptor (RORγt) and IL-17, was significantly decreased upon exposure to serum containing IL-1RII-Ig. In conclusion, hydrodynamics-based delivery of a recombinant plasmid encoding IL-1RII-Ig effectively prevented progression of left ventricular remodeling and myocardial damage in EAM rats. Moreover, IL-1RII may ameliorate experimental autoimmune myocarditis by blocking IL-1 and inhibiting production of the cytokines important for the polarization of T cells toward a Th17 phenotype.

Beneficial effect of a synthetic prostacyclin agonist, ONO-1301, in rat autoimmune myocarditis model

Injury to the heart can result in cardiomyocyte hypertrophy, fibrosis, and cell death. Myocarditis sometimes progresses to dilated cardiomyopathy. We previously reported that ONO-1301, a synthetic prostacyclin agonist with thromboxane-synthase inhibitory activity, promotes production of hepatocyte growth factor (HGF) from various cell types and ameliorates ischemia-induced left ventricle dysfunction in the mouse, rat and pig. Here, we investigated the therapeutic efficacy of ONO-1301 in a rat model of myosin-induced experimental autoimmune myocarditis, in which the heart transits from an acute inflammatory phase to a chronic dilated cardiomyopathy phase. Four weeks after myosin injection to Lewis rats, ONO-1301 (6mg/kg/day) was orally administered for 4 weeks (ONO-1301 group). Hemodynamic parameters and plasma brain natriuretic peptide (BNP) level were significantly improved by ONO-1301. Histological analysis revealed that capillary density in the myocardium was significantly increased by ONO-1301. ONO-1301 increased circulating endothelial progenitor cells (EPC) as determined by FACS analysis. These beneficial effects of ONO-1301 were partially abrogated by a neutralizing anti-HGF antibody (8mg/kg/dose). These findings indicate beneficial effects of ONO-1301 in a rat experimental autoimmune myocarditis model.

Treatment withN-acetyl-seryl-aspartyl-lysyl-proline prevents experimental autoimmune myocarditis in rats

Myocarditis is commonly associated with cardiotropic infections and has been linked to development of autoimmunity. N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a naturally occurring tetrapeptide that prevents inflammation and fibrosis in hypertension and other cardiovascular diseases; however, its effect on autoimmune-mediated cardiac diseases remains unknown. We studied the effects of Ac-SDKP in experimental autoimmune myocarditis (EAM), a model of T cell-mediated autoimmune disease. This study was conducted to test the hypothesis that Ac-SDKP prevents autoimmune myocardial injury by modulating the immune responses. Lewis rats were immunized with porcine cardiac myosin and treated with Ac-SDKP or vehicle. In EAM, Ac-SDKP prevented both systolic and diastolic cardiac dysfunction, remodeling as shown by hypertrophy and fibrosis, and cell-mediated immune responses without affecting myosin-specific autoantibodies or antigen-specific T cell responses. In addition, Ac-SDKP reduced cardiac infiltration by macrophages, dendritic cells, and T cells, pro-inflammatory cytokines [interleukin (IL)-1α, tumor necrosis factor-α, IL-2, IL-17] and chemokines (cytokine-induced neutrophil chemoattractant-1, interferon-γ-induced protein 10), cell adhesion molecules (intercellular adhesion molecule-1, L-selectin), and matrix metalloproteinases (MMP). Ac-SDKP prevents autoimmune cardiac dysfunction and remodeling without reducing the production of autoantibodies or T cell responses to cardiac myosin. The protective effects of Ac-SDKP in autoimmune myocardial injury are most likely mediated by inhibition of 1) innate and adaptive immune cell infiltration and 2) expression of proinflammatory mediators such as cytokines, chemokines, adhesion molecules, and MMPs.

Erythromycin treatment suppresses myocardial injury in autoimmune myocarditis in rats via suppression of superoxide production

BackgroundRecent evidence suggests that erythromycin (EM), a major macrolide antibiotic, has many biological functions in addition to the anti-bacterial actions, including anti-inflammatory and free radical scavenging actions. However, the effects of the drug upon inflammatory myocardial diseases are unknown. We tested the hypothesis that EM ameliorates experimental autoimmune myocarditis in rats attributing to the suppression of superoxide production. MethodsWe administered EM, 3.3mg/kg/day and 33mg/kg/day, intraperitoneally for 3weeks, to rats with experimental autoimmune myocarditis (EAM) produced by immunization by porcine myosin. ResultsEM treatment reduced the severity of myocarditis compared with the untreated group in a dose-dependent manner by comparing the heart weight/body weight ratio, pathologic scores, and myocardial macrophage, CD4+, and CD8+ infiltrations. Echocardiographic study showed that increased left ventricular posterior wall thickness produced by myocardial inflammation was reduced by EM treatment. Myocardial superoxide production, determined by dihydroethidium staining, was significantly reduced by the treatment. Western blotting showed that the expression of myocardial interleukin-1β was reduced by EM treatment compared with untreated groups. The in vivo dorsal air pouch model showed that EM significantly suppressed leukocyte chemotaxis in a dose-dependent manner. ConclusionIrrespective of a well-known classic antibiotic, EM attenuated EAM not only by the anti-inflammatory action but by the suppression of superoxide production.

Involvement of AMPK and MAPK signaling during the progression of experimental autoimmune myocarditis in rats and its blockade using a novel antioxidant

There are various reports suggesting the role of angiotensin (Ang) receptor blockers, Ang converting enzyme inhibitors, calcium channel blockers, diuretics and antioxidants against the progression of experimental autoimmune myocarditis (EAM) to dilated cardiomyopathy (DCM). Most of them were reported to be effective during this adverse cardiac remodeling. Recently much attention has been paid to studying the involvement of AMP-activated protein kinase (AMPK) and mitogen activated protein kinase (MAPK) in various cardiovascular ailments. AMPK acts as a master sensor of cellular energy balance via maintenance of lipid and glucose metabolism. Evidences also suggest the relation between AMPK and oxidative stress during physiological and pathological myocardial cellular function. Since, it is of interest to identify the roles of AMPK and MAPK during the progression of EAM to DCM and also the effect of edaravone, a novel free radical scavenger, against its progression. For this, we have carried out western blotting, histopathological staining and immunohistochemical analyses to measure the myocardial expressions of AMPK signaling and oxidative stress related parameters in normal and vehicle or edaravone-treated EAM rats, respectively. We identified the myocardial levels of phospho Akt and phosphoinositide 3-kinase, which are the upstream proteins of AMPK and MAPK activation and both were up-regulated in the vehicle-treated rats, whereas candesartan treatment significantly reversed these changes. We have also measured the myocardial levels of p-AMPKα, different isoforms of protein kinase C and MAPK signaling proteins. All of these protein levels were significantly elevated in the hearts of DCM rats whereas edaravone treatment significantly reversed these changes. In viewing these results, we can suggest that along with MAPK, AMPK signaling also plays a crucial role in the progression of EAM and it can be effectively blocked by the treatment with a novel antioxidant, edaravone.

Olmesartan attenuates the development of heart failure after experimental autoimmune myocarditis in rats through the modulation of ANG 1–7 mas receptor

Angiotensin-converting enzyme 2 (ACE-2) is a membrane-associated carboxy-peptidase catalyzes the conversion of the vasoconstrictor angiotensin (ANG)-II to the vasodilatory peptide ANG 1–7. In view of the expanding axis of the renin angiotensin system, we have investigated the cardioprotective effects of olmesartan (10mg/kg/day) in experimental autoimmune myocarditis. Olmesartan treatment effectively suppressed the myocardial protein expressions of inflammatory markers in comparison to the vehicle-treated rats. However, the protein and mRNA levels of ACE-2 and ANG 1–7, and its receptor Mas were upregulated in olmesartan treated group compared to vehicle-treated rats. Olmesartan medoxomil treatment significantly decreased the expression levels of phospho-p38 mitogen-activated protein kinase (MAPK), phospho-JNK, phospho-ERK and phospho-(MAPK) activated protein kinase-2 than with those of vehicle-treated rats. Moreover, vehicle-treated rats were shown to be up-regulated protein expressions of NADPH oxidase subunits (p47phox, p67phox and Nox-4), myocardial apoptotic markers and endoplasmic reticulum stress markers in comparison to those of normal and all these effects are expectedly down-regulated by an olmesartan. In addition, attenuated protein levels of phosphatidylinositol-3-kinase (PI3K) and phospho-Akt in the vehicle-treated EAM rats were prevented by olmesartan treatment. Our results suggest that beneficial effects of olmesartan treatment was more effective therapy in combating the inflammation, oxidative stress, apoptosis and signaling pathways associated with heart failure at least in part via the modulation of ANG 1–7 mas receptor.

Modulation of endoplasmic reticulum stress and cardiomyocyte apoptosis by mulberry leaf diet in experimental autoimmune myocarditis rats

Mulberry is commonly used as silkworm diet and an alternative medicine in Japan and China, has recently reported to contain many antioxidative flavanoid compounds and having the free radical scavenging effects. Antioxidants reduce cardiac oxidative stress and attenuate cardiac dysfunction in animals with pacing-induced congestive heart failure. Hence we investigated the cardioprotective effect of mulberry leaf powder in rats with experimental autoimmune myocarditis. Eight-week-old Lewis rats immunized with cardiac myosin were fed with either normal chow or a diet containing 5% mulberry leaf powder and were examined on day 21. ML significantly decreased oxidative stress, myocyte apoptosis, cellular infiltration, cardiac fibrosis, mast cell density, myocardial levels of sarco/endo-plasmic reticulum Ca2+ ATPase2, p22phox, receptor for advanced glycation end products, phospho-p38 mitogen activated protein kinase, phospho-c-Jun NH2-terminal protein kinase, glucose regulated protein78, caspase12 and osteopontin levels in EAM rats. These results may suggest that mulberry diet can preserve the cardiac function in experimental autoimmune myocarditis by modulating oxidative stress induced MAPK activation and further afford protection against endoplasmic reticulum stress mediated apoptosis.

Proteomic and biochemical analyses reveal the activation of unfolded protein response, ERK-1/2 and ribosomal protein S6 signaling in experimental autoimmune myocarditis rat model.

BackgroundTo investigate the molecular and cellular pathogenesis underlying myocarditis, we used an experimental autoimmune myocarditis (EAM)-induced heart failure rat model that represents T cell mediated postinflammatory heart disorders.ResultsBy performing unbiased 2-dimensional electrophoresis of protein extracts from control rat heart tissues and EAM rat heart tissues, followed by nano-HPLC-ESI-QIT-MS, 67 proteins were identified from 71 spots that exhibited significantly altered expression levels. The majority of up-regulated proteins were confidently associated with unfolded protein responses (UPR), while the majority of down-regulated proteins were involved with the generation of precursor metabolites and energy metabolism in mitochondria. Although there was no difference in AKT signaling between EAM rat heart tissues and control rat heart tissues, the amounts and activities of extracellular signal-regulated kinase (ERK)-1/2 and ribosomal protein S6 (rpS6) were significantly increased. By comparing our data with the previously reported myocardial proteome of the Coxsackie viruses of group B (CVB)-mediated myocarditis model, we found that UPR-related proteins were commonly up-regulated in two murine myocarditis models. Even though only two out of 29 down-regulated proteins in EAM rat heart tissues were also dysregulated in CVB-infected rat heart tissues, other proteins known to be involved with the generation of precursor metabolites and energy metabolism in mitochondria were also dysregulated in CVB-mediated myocarditis rat heart tissues, suggesting that impairment of mitochondrial functions may be a common underlying mechanism of the two murine myocarditis models.ConclusionsUPR, ERK-1/2 and S6RP signaling were activated in both EAM- and CVB-induced myocarditis murine models. Thus, the conserved components of signaling pathways in two murine models of acute myocarditis could be targets for developing new therapeutic drugs or methods aimed at treating enigmatic myocarditis.

Inhibition of cardiac oxidative and endoplasmic reticulum stress-mediated apoptosis by curcumin treatment contributes to protection against acute myocarditis

Curcumin is used anecdotally as an herb in traditional Indian and Chinese medicine. In the present study, the effects and possible mechanism of curcumin in experimental autoimmune myocarditis (EAM) rats were further investigated. They were divided randomly into a treatment and vehicle group, and orally administrated curcumin (50 mg/kg/day) and 1% gum arabic, respectively, for 3 weeks after myosin injection. The results showed that curcumin significantly suppressed the myocardial protein expression of inducible nitric oxide synthase (iNOS) and the catalytic subunit of nicotinamide adenine dinucleotide phosphate reduced (NADPH) oxidase. In addition, curcumin significantly decreased myocardial endoplasmic reticulum (ER) stress signaling proteins and improved cardiac function. Furthermore, curcumin significantly decreased the key regulators or inducers of apoptosis. In summary, our results indicate that curcumin has the potential to protect EAM by modulating cardiac oxidative and ER stress-mediated apoptosis, and provides a novel therapeutic strategy for autoimmune myocarditis.

Telmisartan ameliorates experimental autoimmune myocarditis associated with inhibition of inflammation and oxidative stress

Excess cytokine produced by inflammatory stimuli contributes to the progression of myocardial damage in myocarditis. Angiotensin-II has been shown to play a pivotal role in the pathophysiology of various organs, especially the cardiovascular system. Some angiotensin II type 1 receptor antagonists are reported to inhibit proinflammatory cytokine production in vitro and in vivo. We investigated whether telmisartan, an angiotensin II type 1 receptor antagonist protects against experimental autoimmune myocarditis by suppression of inflammatory cytokines and oxidative stress. Experimental autoimmune myocarditis was induced in Lewis rats by immunization with porcine cardiac myosin. The rats were divided into two groups and treated with either telmisartan (10 mg/kg/day) or vehicle for 21 days. Age-matched normal rats without immunization were also included in this study. Myocardial functional parameters were significantly improved by treatment with telmisartan compared with vehicle-treated rats. Increased myocardial mRNA expressions of inflammatory cytokines [interleukin (IL-6), IL-1β, tumor necrosis factor-α and interferon-γ] were also suppressed by telmisartan treatment compared with vehicle-treated rats. Myocardial protein expressions of NADPH oxidase subunits p47phox, Nox-4, and gp91phox, myocardial levels of 8-hydroxydeoxyguanosine and 4-hydroxy-2-nonenal, and myocardial apoptosis were also significantly decreased by telmisartan treatment compared with vehicle-treated rats. Further, telmisartan significantly decreased endoplasmic reticulum stress markers in experimental autoimmune myocarditis rats. These findings suggest that telmisartan protects against experimental autoimmune myocarditis in rats, at least in part by suppressing inflammatory cytokines and oxidative stress; however, further investigations are needed before clinical use.

Dynamics of development of autoimmune myocarditis in rats

The development of autoimmune myocarditis in rats after a single subcutaneous injection of rat myosin mixed with a complete Freund's adjuvant (CFA) (400 µg/kg in 200 µl) was studied. The rats from the control group were injected with only CFA. The titer of antibodies to myosin, infiltration of lymphocytes into the myocardium, ultrastructural damage of myofibrils, mitochondria, and nuclei of cardiomyocytes were maximally pronounced on days 14-21 after the immunization with myosin, which indicates a peak of the inflammatory reaction. The content of nitrites and nitrates in the blood serum and myocardium of immu� nized rats were also studied. A certain contribution to the development of the inflammation is made by CFA: in rats injected with only CFA, morphological signs of myocarditis were found, but to a much lesser degree than in the group immunized with myosin.

The Inhibitor of NF-κB Kinase Plays a Pivotal Role in the Development of Autoimmune Myocarditis in Rats

Background: Nuclear factor-kappa B (NF-κB), which is regulated by inhibitor of NF-κB kinase (IKK), plays a critical role in the development of myocarditis. However, little is known about the role of IKK in its pathophysiology. We assessed the hypothesis that IKK inhibition could attenuate cardiac inflammation in the progression of myocarditis. Materials and Methods: We administered the IKK inhibitor (IMD-0354, 15mg/kg/day) to experimental autoimmune myocarditis (EAM) rats daily (n=6). The drug-free vehicle was used as control (n=6).

Early treatment with clarithromycin attenuates rat autoimmune myocarditis via inhibition of matrix metalloproteinase activity

BackgroundMatrix metalloproteinase (MMP) activity is upregulated in the hearts with myocarditis, and its activation contributes to the changes in left ventricular function. A major macrolide antibiotic, clarithromycin (CAM), has many...

Therapy with granulocyte colony-stimulating factor in the chronic stage, but not in the acute stage, improves experimental autoimmune myocarditis in rats via nitric oxide

We systematically investigated serial efficacy of granulocyte colony-stimulating factor (G-CSF) therapy upon experimental autoimmune myocarditis (EAM) in rats treated with and without the inhibition of nitric oxide (NO) with the analyses of tissue regeneration. G-CSF could mobilize multipotent progenitor cells of bone marrow into the peripheral blood and may improve ventricular function. A rat model of porcine myosin-induced EAM was used. After the immunization of myosin, G-CSF (10 μg/kg/day) or saline was injected intraperitoneally on days 0–21 in experiment 1 and on days 21–42 in experiment 2. Additional myosin-immunized rats were orally given 25 mg/kg/day of N G -nitro- l-arginine methylester ( l-NAME), an inhibitor of nitric oxide synthase (NOS), in each experiment (each group; n = 8–21). Serum cytokines and peripheral blood cell counts were measured in each group. In experiment 1, G-CSF treatment aggravated cardiac pathology associated with increased macrophage inflammatory protein-2 (MIP-2) and interleukin-6 (IL-6) levels and enhanced superoxide production. In experiment 2, G-CSF treatment reduced the severity of myocarditis with increased capillary density and improved left ventricular ejection fraction. In the rats with EAM treated with G-CSF associated with oral l-NAME treatment in experiment 2, the severity of myocarditis was not reduced. Myocardial c-kit + cells were demonstrated only in G-CSF-treated group in experiment 2 but not in other groups. G-CSF has differential effects on EAM in rats associated with the modulation of cytokine network. The overwhelming superoxide production by G-CSF administration in the acute stage may worsen the disease. G-CSF therapy improved cardiac function via NO system in a rat model of myocarditis in the chronic stage, but not in the acute stage, possibly through the myocardial regeneration and acceleration of healing process.

126: Adipocyte Sheets Derived from Stromal Vascular Cells Ameliorate Left Ventricular Dysfunction through Suppression of Inflammatory Response in Autoimmune Myocarditis Rats

We hypothesized whether a novel cell sheet-based adiponectin delivery system by using adipocyte sheets might ameliorate left ventricular dysfunction through suppression of inflammatory response in autoimmune myocarditis rats.

Suppression of inflammation in rat autoimmune myocarditis by S100A8/A9 through modulation of the proinflammatory cytokine network

S100A8/A9 is expressed in activated monocytes/macrophages and assumed to be heavily involved in the pathogenesis of acute inflammation. Although several studies have asserted that S100A8/A9 has a proinflammatory function, the exact biological function of S100A8/A9 is yet to be described. We examined the anti-inflammatory effects of S100A8/A9 on experimental autoimmune myocarditis (EAM) in rats. Experimental autoimmune myocarditis was induced in Lewis rats by immunization with porcine cardiac myosin. The recombinant (R-) S100A8/A9 was injected intraperitoneally into EAM rats. R-S100A8/A9 attenuated the severity of myocarditis, as evidenced by echocardiographic and histological findings. In addition, we found that not only the mRNA expression of proinflammatory cytokines [interleukin (IL)-1beta, IL-6, and tumour necrosis factor (TNF)-alpha] in the myocardium, but also their serum concentrations were suppressed in EAM rats treated with R-S100A8/A9. Nuclear factor-kappa B expression in inflammatory cells was also suppressed in the treated rats. To elucidate the mechanistic function of S100A8/A9 on proinflammatory cytokines in vivo, we used an ELISA on the supernatant of homogenized heart tissue treated with R-S100A8/A9. The findings revealed high-affinity binding of R-S100A8/A9 with IL-1beta, IL-6, and TNF-alpha in the myocardium, suggesting the trapping of proinflammatory cytokines by R-S100A8/A9. S100A8/A9 attenuates EAM through modulation of the proinflammatory cytokine network.

Crosstalk between component cells in rat autoimmune myocarditis with cytokine/chemokine

It is known that several factors such as virus infection and autoimmune cause myocarditis. Therefore, mechanisms of its onset and recovery are predicted to greatly differ with the causes of myocarditis. However, the vast majority of myocarditis display severe pathological changes with inflammatory cells and the crosstalk of component cells with cytokines/chemokines is thought to be a common mechanism in any kind of myocarditis. In rat experimental autoimmune myocarditis (EAM), there are dendritic cells, macrophages, granulocytes, T cells, cardiomyocytes and non-cardiomyocytic non-inflammatory (NCNI) cells such as fibroblasts, smooth muscle cells and endothelial cells at sites of myocarditis lesions.

Suppression of inflammation in rat autoimmune myocarditis by S100A8/A9 through modulation of the proinflammatory cytokine network

Suppression of inflammation in rat autoimmune myocarditis by S100A8/A9 through modulation of the proinflammatory cytokine network

Gene expression profiles of cardiomyocytes in rat autoimmune myocarditis by DNA microarray and increase of regenerating gene family

Cardiomyocytes with myocarditis compared with the normal state are thought to change the expressions of various genes greatly, some of which may be new biomarkers or new biologic medicinal products. However, until now, little comprehensive analysis has been made of gene-expression changes in cardiomyocytes with myocarditis. In this study, we performed a DNA microarray analysis by using cardiomyocytes from rat experimental autoimmune myocarditis (EAM). On day 0, rats were immunized with porcine cardiac myosin and cardiomyocytes were isolated and purified from EAM hearts and normal hearts by a method that is hardly thought to change gene expressions in cardiomyocytes. RNA from normal cardiomyocytes and cardiomyocytes of EAM on day 18 was analyzed for 7711 gene expressions by DNA microarray. Some gene expressions showed over 10-fold changes. In particular, the regenerated gene (Reg)2/pancreatitis-associated protein (PAP)1 messenger RNA (mRNA) level most markedly increased in the genes, which were clearly expressed in cardiomyocytes rather than in noncardiomyocytes, and it was approximately 2000-fold greater in cardiomyocytes under active myocarditis than normal by real-time reverse transcription polymerase chain reaction analysis. Moreover, we demonstrated that Reg2/PAP1 proteins determined by Western blot analysis and immunohistochemistry and other Reg/PAP family gene expressions were remarkably increased in EAM hearts; in addition, interleukin (IL)-6 expression was significantly related to Reg2/PAP1. It seemed that these data were useful as a reference database of gene-expression changes in cardiomyocytes with myocarditis. The Reg/PAP family, which was found to show dramatically increasing gene expressions by DNA microarray analysis, was suspected to play an important role in myocarditis.

Torasemide, a long-acting loop diuretic, reduces the progression of myocarditis to dilated cardiomyopathy

Torasemide is a long-acting loop diuretic that combines the effects of both furosemide and spironolactone. It has been reported that torasemide may block the renin–angiotensin–aldosterone system and therefore it might attenuate myocardial remodeling accompanied by left ventricular dysfunction. However, nothing is known about the effect of torasemide on myocardial remodeling in a rat model in which myosin-induced experimental autoimmune myocarditis might develop into dilated cardiomyopathy. Experimental autoimmune myocarditis was elicited in Lewis rats by immunization with porcine cardiac myosin. Twenty-eight days after immunization, we investigated the effects of torasemide on metabolic and neurohumoral parameters, cardiac fibrosis and remodeling in experimental autoimmune myocarditis rats. Diuresis was increased dose-dependently by torasemide; the urinary potassium and sodium excretion was significantly decreased and increased, respectively. Myocardial functional parameters measured by hemodynamic and echocardiographic studies were significantly improved by torasemide treatment in a dose-dependent manner. The area of fibrosis, myocyte size and the myocardial protein levels of transforming growth factor-beta1, collagen III, and aldosterone synthase were significantly decreased, and the sarcoplasmic reticulum Ca 2+ ATPase2 protein level was significantly increased by torasemide treatment. Moreover, the plasma levels of angiotensin II and aldosterone were increased and atrial natriuretic peptide was decreased in a dose-dependent manner. Our results indicate that torasemide treatment significantly improved left ventricular function and ameliorated the progression of cardiac remodeling beyond its renal effects in rats with chronic heart failure after experimental autoimmune myocarditis.