Effects of prednisolone on acute viral myocarditis in mice

Assessing the Anti-Inflammatory and Antioxidant Activity of Mangiferin in Murine Model for Myocarditis: Perspectives and Challenges

Myocarditis is a major cause of heart failure and death, particularly in young individuals. Current treatments are mainly symptomatic, but emerging therapies focus on targeting inflammation and fibrosis pathways. Natural bioactive compounds like flavonoids and phenolic acids show promising anti-inflammatory and antioxidant properties. Corticosteroids are frequently employed in the treatment of autoimmune myocarditis and appear to lower mortality rates compared to conventional therapies for heart failure. This study aims to explore the effects of Mangiferin on pro-inflammatory cytokine levels, nitro-oxidative stress markers, histopathological alterations, and cardiac function in experimental myosin-induced autoimmune myocarditis. The effects were compared to Prednisone, used as a reference anti-inflammatory compound, and Trolox, used as a reference antioxidant. The study involved 30 male Wistar-Bratislava rats, which were randomly divided into five groups: a negative control group (C-), a positive control group with induced myocarditis using a porcine myosin solution (C+), three groups with induced myocarditis receiving Mangiferin (M), Prednisone (P), or Trolox (T) as treatment. Cardiac function was evaluated using echocardiography. Biochemical measurements of nitro-oxidative stress and inflammatory markers were conducted. Finally, histopathological changes were assessed. At echocardiography, the evaluation of the untreated myocarditis group showed a trend toward decreased left ventricular ejection fraction (LVEF) but was not statistically significant, while all treated groups showed some improvement in LVEF and left ventricular fraction shortening (LVFS). Significant changes were seen in the Mangiferin group, with lower end-diastolic left ventricular posterior wall (LVPWd) by day 21 compared to the Trolox group (p < 0.001). In the first week of the experiment, levels of interleukins (IL)-1β, IL-6, and tumour necrosis factor (TNF)-α were significantly higher in the myosin group compared to the negative control group (p < 0.001, p < 0.001, p < 0.01), indicating the progression of inflammation in this group. Treatment with Mangiferin, Prednisone, and Trolox caused a significant reduction in IL-1β compared to the positive control group (p < 0.001). Notably, Mangiferin resulted in a superior reduction in IL-1β compared to Prednisone (p < 0.05) and Trolox (p < 0.05). Furthermore, Mangiferin treatment led to a statistically significant increase in total oxidative capacity (TAC) (p < 0.001) and a significant reduction in nitric oxide (NOx) levels (p < 0.001) compared to the negative control group. Furthermore, when compared to the Prednisone-treated group, Mangiferin significantly reduced NOx levels (p < 0.001) and increased TAC levels (p < 0.001). Mangiferin treatment significantly lowered creatine kinase (CK) and aspartate aminotransferase (AST) levels on day 7 (p < 0.001 and p < 0.01, respectively) and reduced CK levels on day 21 (p < 0.01) compared to the untreated group. In the nontreated group, the histological findings at the end of the experiment were consistent with myocarditis. In the group treated with Mangiferin, only one case exhibited mild inflammatory infiltrates, represented by mononucleated leukocytes admixed with few neutrophils, with the severity graded as mild. Statistically significant correlations between the grades (0 vs. 1-2) and the study groups have been highlighted (p < 0.005). This study demonstrated Mangiferin's cardioprotective effects in autoimmune myocarditis, showing reduced oxidative stress and inflammation. Mangiferin appears promising as a treatment for acute myocarditis, but further research is needed to compare its efficacy with other treatments like Trolox and Prednisone.

Analyzing the Systems Biology Effects of COVID-19 mRNA Vaccines to Assess Their Safety and Putative Side Effects

COVID-19 vaccines have been instrumental tools in reducing the impact of SARS-CoV-2 infections around the world by preventing 80% to 90% of hospitalizations and deaths from reinfection, in addition to preventing 40% to 65% of symptomatic illnesses. However, the simultaneous large-scale vaccination of the global population will indubitably unveil heterogeneity in immune responses as well as in the propensity to developing post-vaccine adverse events, especially in vulnerable individuals. Herein, we applied a systems biology workflow, integrating vaccine transcriptional signatures with chemogenomics, to study the pharmacological effects of mRNA vaccines. First, we derived transcriptional signatures and predicted their biological effects using pathway enrichment and network approaches. Second, we queried the Connectivity Map (CMap) to prioritize adverse events hypotheses. Finally, we accepted higher-confidence hypotheses that have been predicted by independent approaches. Our results reveal that the mRNA-based BNT162b2 vaccine affects immune response pathways related to interferon and cytokine signaling, which should lead to vaccine success, but may also result in some adverse events. Our results emphasize the effects of BNT162b2 on calcium homeostasis, which could be contributing to some frequently encountered adverse events related to mRNA vaccines. Notably, cardiac side effects were signaled in the CMap query results. In summary, our approach has identified mechanisms underlying both the expected protective effects of vaccination as well as possible post-vaccine adverse effects. Our study illustrates the power of systems biology approaches in improving our understanding of the comprehensive biological response to vaccination against COVID-19.

Shedding the Light on Post-Vaccine Myocarditis and Pericarditis in COVID-19 and Non-COVID-19 Vaccine Recipients

Myocarditis and pericarditis have been linked recently to COVID-19 vaccines without exploring the underlying mechanisms, or compared to cardiac adverse events post-non-COVID-19 vaccines. We introduce an informatics approach to study post-vaccine adverse events on the systems biology level to aid the prioritization of effective preventive measures and mechanism-based pharmacotherapy by integrating the analysis of adverse event reports from the Vaccine Adverse Event Reporting System (VAERS) with systems biology methods. Our results indicated that post-vaccine myocarditis and pericarditis were associated most frequently with mRNA COVID-19 vaccines followed by live or live-attenuated non-COVID-19 vaccines such as smallpox and anthrax vaccines. The frequencies of cardiac adverse events were affected by vaccine, vaccine type, vaccine dose, sex, and age of the vaccinated individuals. Systems biology results suggested a central role of interferon-gamma (INF-gamma) in the biological processes leading to cardiac adverse events, by impacting MAPK and JAK-STAT signaling pathways. We suggest that increasing the time interval between vaccine doses minimizes the risks of developing inflammatory adverse reactions. We also propose glucocorticoids as preferred treatments based on system biology evidence. Our informatics workflow provides an invaluable tool to study post-vaccine adverse events on the systems biology level to suggest effective mechanism-based pharmacotherapy and/or suitable preventive measures.

Viruses in the Heart: Direct and Indirect Routes to Myocarditis and Heart Failure

Viruses are an underappreciated cause of heart failure. Indeed, several types of viral infections carry cardiovascular risks. Understanding shared and unique mechanisms by which each virus compromises heart function is critical to inform on therapeutic interventions. This review describes how the key viruses known to lead to cardiac dysfunction operate. Both direct host-damaging mechanisms and indirect actions on the immune systems are discussed. As viral myocarditis is a key pathologic driver of heart failure in infected individuals, this review also highlights the role of cytokine storms and inflammation in virus-induced cardiomyopathy.

SARS-CoV-2 Myocarditis: Insights Into Incidence, Prognosis, and Therapeutic Implications

PURPOSE OF REVIEW

In coronavirus disease 2019 (COVID-19), myocardial injury occurs frequently in severe or critically ill hospitalized patients, yet myocarditis is much less common. In this context, revisiting the definition of myocarditis is appropriate with a specific focus on diagnostic and management considerations in patients infected with SARS-CoV-2.

RECENT FINDINGS

Pathologic cardiac specimens from patients with COVID-19 suggest a mixed inflammatory response involving lymphocytes and macrophages, and importantly, cellular injury occurs predominantly at the level of pericytes and endothelial cells, less often involving direct myocyte necrosis. In COVID-19, the diagnosis of myocarditis has understandably been based predominantly on clinical criteria, and the number of patients with clinically suspected myocarditis who would meet diagnostic histological criteria is unclear. Echocardiography and cardiac magnetic resonance are important diagnostic tools, although the prognostic implications of abnormalities are still being defined. Importantly, SARS-CoV2 myocarditis should be diagnosed within an appropriate clinical context and should not be based on isolated imaging findings. Therapies in COVID-19 have focused on the major clinical manifestation of pneumonia, but the promotion of viral clearance early in the disease could prevent the development of myocarditis, and further study of immunosuppressive therapies once myocarditis has developed are indicated. A strict and uniform approach is needed to diagnose myocarditis due to SARS-CoV-2 to better understand the natural history of this disease and to facilitate evaluation of potential therapeutic interventions. A methodological approach will also better inform the incidence of COVID-19 associated myocarditis and potential long-term health effects.

[Myocarditis]

Acute myocarditis must be considered in patients with recent onset of cardiac failure or arrhythmia. Fulminant myocarditis is a distinct entity characterized by sudden onset of severe congestive heart failure or cardiogenic shock, usually following a flu-like illness, parvovirus B19, human herpesvirus 6, coxsackie virus and adenovirus being the most frequently viruses responsible for the disease. In this setting, early recognition of patients rapidly progressing to refractory cardiac failure and their immediate transfer to a medical-surgical center experienced in mechanical circulatory support is warranted. Treatment of acute myocarditis relies on conventional heart failure therapy. Immunosuppression of autoreactive myocarditis or immuno-stimulants such as interferons for chronic viral myocarditis could be of interest but their potential therapeutic role requires further investigation.

Viral kinetics are associated with changes in cytokines and chemokines in serum and target organs of SSM-CVB3-infected macaques

OBJECTIVE

To determine the relationship between viral kinetics and the expression patterns for different cytokines and chemokines in the serum and organs of coxsackievirus B3 (SSM-CVB3)-infected macaques over the course of infection.

METHODS

SSM-CVB3 levels in serum and organs were measured using the Spearman-Karber 50% tissue culture infectious dose (TCID(50)) method. Cytokine and chemokine levels in the serum and organs were measured by indirect-ELISA.

RESULTS

Low viral titers were detected in the serum samples on the first day post-inoculation (p.i.) and peaked at 6 to 10 days p.i. in the serum samples from five macaques. Serum levels of IL-1β, IL-2, IL-6, IL-12p40, IL-17α, IFN-γ, TNF-α, MCP-1 and MIP-1β were detected each day and, similar to the viral titers, peaked at 6 to 10 days. IL-10 was only detected on days 10 to 14 p.i. Additionally, higher viral titers and relative viral mRNA levels were associated with higher cytokine and chemokine levels in selected tissues from infected macaques including heart, liver, spleen, lung, kidney and brain.

CONCLUSION

The results indicate that patterns of cytokine and chemokine response are associated with viral kinetics in the serum and target organs of SSM-CVB3-infected macaques, suggesting that the changes in cytokines and chemokines could help further our understanding of the progress of CVB3 infections in clinical settings.

[Acute myocarditis]

Myocarditis is defined as inflammation of the myocardium accompanied by myocellular necrosis. Acute myocarditis must be considered in patients who present with recent-onset of cardiac failure or arrhythmia. Fulminant myocarditis is a distinct entity characterized by sudden onset of severe congestive heart failure or cardiogenic shock, usually following a flu-like illness, parvovirus B19, human herpesvirus 6, coxsackievirus and adenovirus being the most frequently viruses responsible for the disease. Treatment of myocarditis remains largely supportive, since immunosuppression has not been proven to be beneficial for acute lymphocytic myocarditis. Trials of antiviral therapies, or immunostimulants such as interferons, suggest a potential therapeutic role but require further investigation. Lastly, early recognition of patients rapidly progressing to refractory cardiac failure and their immediate transfer to a medical-surgical center experienced in mechanical circulatory support is warranted. In this setting, ECMO should be the first-line mechanical assistance. For highly unstable patients, a Mobile Cardiac Assistance Unit, that rapidly travels to primary care hospitals with a portable ECMO system and hooks it up before refractory multiorgan failure takes hold, is the preferred option.

Viral causes of human myocarditis

The diagnosis of acute myocarditis is complex and challenging. The use of the Dallas criteria in the diagnosis of myocarditis is associated with poor sensitivity and specificity because of the sampling error related to the often focal distribution of the specific histological lesions in cardiac tissue and the variability in pathological interpretation. To improve histological diagnosis, additional virological evaluation of cardiac tissues is required, with immunohistochemical and polymerase chain reaction (PCR) techniques allowing identification and quantification of viral infection markers. The diagnostic gold standard is endomyocardial biopsy (EMB) with the histological Dallas criteria, in association with new immunohistochemical and PCR analyses of cardiac tissues. Using real-time PCR and reverse transcription PCR assays, parvovirus B19, Coxsackie B virus, human herpesvirus 6 (HHV-6) type B and adenovirus have been detected in 37, 33, 11 and 8% of EMB, respectively, from young adults (aged<35 years) with histologically proven acute myocarditis. Viral co-infections have also been found in 12% of acute myocarditis cases, generally parvovirus B19 plus HHV-6. Moreover, herpesviruses such as the Epstein-Barr virus or cytomegalovirus can also be associated with myocarditis after heart transplantation. During the clinical course of myocarditis, the immunohistochemical detection of enterovirus, adenovirus or parvovirus B19 capsid proteins or herpesvirus late proteins is necessary to differentiate a viral cardiac infection with replication activities from a persistent or latent cardiac infection. These new viral diagnostic approaches can lead to better identification of the aetiology of myocarditis and may therefore enable the development and evaluation of specific aetiology-directed treatment strategies.

Role of the innate immune system in acute viral myocarditis

Although the adaptive immune system is thought to play an important role in the pathogenesis of viral myocarditis, the role of the innate immune system has not been well defined. To address this deficiency, we employed a unique line of mice that harbor a genomic "knock in" of a mutated TNF gene lacking the AU rich element (TNF(ARE/ARE)) that is critical for TNF mRNA stability and translation, in order to examine the contribution of the innate immune system in encephalomyocarditis-induced myocarditis (EMCV). Heterozygous mice (TNF(ARE/+)) were infected with 500 plaque-forming units of EMCV. TNF(ARE/+)mice had a significantly higher 14-day mortality and myocardial inflammation when compared to littermate control mice. Virologic studies showed that the viral load at 14 days was significantly lower in the hearts of TNF(ARE/+) mice. TNF(ARE/+) mice had an exaggerated proinflammatory cytokine and chemokine response in the heart following EMCV infection. Modulation of the innate immune response in TNF(ARE/+) mice by the late administration of prednisolone resulted in a significant improvement in survival and decreased cardiac inflammation, whereas early administration of prednisolone resulted in a blunted innate response and increased mortality in littermate control mice. Viewed together, these data suggest that the duration and degree of activation of the innate immune system plays a critical role in determining host outcomes in experimental viral myocarditis.

Molecular diagnosis of the viral component in cardiomyopathies: pathophysiological, clinical and therapeutic implications

BACKGROUND

Myocarditis is defined as the inflammation of myocardium associated with cardiac dysfunction. Despite this clear-cut definition, diagnosis and etiologic treatment continue to create considerable debate. Viral infections are frequent causes of myocarditis and there is evidence that persistent viral infection is associated with poor prognosis in different subtypes of cardiomyopathy.

OBJECTIVE

To review methods for diagnosis of viral myocarditis and present the use of polymerase chain reaction (PCR)-based protocols for evaluating viral infection in myocarditis/cardiomyopathies.

METHODS

A review of published literature.

RESULTS/CONCLUSION

There is increasing evidence that PCR-based protocols can provide reliable molecular evidence for the presence of viral infection in myocardium. Thus application of molecular techniques will allow collection and analysis of more information on the epidemiology of viral cardiomyopathies, patient risk stratification and appropriate medical treatment.

Molecular biology and pathogenesis of viral myocarditis

Myocarditis is a cardiac disease associated with inflammation and injury of the myocardium. Several viruses have been associated with myocarditis in humans. However, coxsackievirus B3 is still considered the dominant etiological agent. The observed pathology in viral myocarditis is a result of cooperation or teamwork between viral processes and host immune responses at various stages of disease. Both innate and adaptive immune responses are crucial determinants of the severity of myocardial damage, and contribute to the development of chronic myocarditis and dilated cardiomyopathy following acute viral myocarditis. Advances in genomics and proteomics, and in the use of informatics and biostatistics, are allowing unbiased initial evaluations that can be the basis for testable hypotheses about virus pathogenesis and new therapies.

Pulmonary and cardiac infections in athletes

Pulmonary and cardiac infections in the athlete can have a wide range of presentations and complications. These infections may present few problems for the training athlete or become life threatening. The team physician must be able to make an accurate diagnosis, give the appropriate treatment, understand the potential complications, and ensure proper follow-up and return-to-play protocols.

Myocarditis

Viruses are the most common cause of myocarditis in economically advanced countries.

Enteroviruses and adenoviruses are the most common etiologic agents.

Viral myocarditis is a triphasic process. Phase 1 is the period of active viral replication in the myocardium during which the symptoms of myocardial damage range from none to cardiogenic shock. If the disease process continues, it enters phase 2, which is characterized by autoimmunity triggered by viral and myocardial proteins. Heart failure often appears for the first time in phase 2. Phase 3, dilated cardiomyopathy, is the end result in some patients. Diagnostic procedures and treatment should be tailored to the phase of disease.

Viral myocarditis is a significant cause of dilated cardiomyopathy, as proved by the frequent presence of viral genomic material in the myocardium, and by improvement in ventricular function by immunomodulatory therapy.

Myocarditis of any etiology usually presents with heart failure, but the second most common presentation is ventricular arrhythmia. As a result, myocarditis is one of the most common causes of sudden death in young people and others without preexisting structural heart disease.

Myocarditis can be definitively diagnosed by endomyocardial biopsy. However, it is clear that existing criteria for the histologic diagnosis need to be refined, and that a variety of molecular markers in the myocardium and the circulation can be used to establish the diagnosis.

Treatment of myocarditis has been generally disappointing. Accurate staging of the disease will undoubtedly improve treatment in the future. It is clear that immunosuppression and immunomodulation are effective in some patients, especially during phase 2, but may not be as useful in phases 1 and 3. Since myocarditis is often selflimited, bridging and recovery therapy with circulatory assistance may be effective. Prevention by immunization or receptor blocking strategies is under development.

Giant cell myocarditis is an unusually fulminant form of the disease that progresses rapidly to heart failure or sudden death. Rapid onset of disease in young people, especially those with other autoimmune manifestations, accompanied by heart failure or ventricular arrhythmias, suggests giant cell myocarditis.

Peripartum cardiomyopathy in economically developed countries is usually the result of myocarditis.

Inflammation and cardiac remodeling during viral myocarditis

Acute viral myocarditis is the main cause of cardiac failure in young patients and accounts for up to 60% of "idiopathic" dilated cardiomyopathy. The clinical course of viral myocarditis is mostly insidious with limited cardiac inflammation and dysfunction. However, overwhelming inflammation may occur in a subset of patients, leading to fulminant cardiac injury, whereas others develop chronic heart failure due to autoimmune myocarditis. Today, little effective treatment exists for patients, apart from general supportive therapy and antifailure regimens. Urokinase-type plasminogen activator (u-PA) and matrix metalloproteinases (MMP) have been implicated in cardiac inflammation, matrix remodeling, and wound healing after cardiac injury. The present review will assess the mechanism by which these proteinases mediate cardiac dilatation, fibrosis, and dysfunction after cardiac stress or injury, in order to understand how inhibition of proteinases may provide a novel therapeutic tool to prevent cardiac dilatation and failure during viral myocarditis.

Emerging treatments for viral myocarditis

Although viral myocarditis has been mostly attributed to enterovirus and adenovirus infection, the importance of hepatitis C virus has recently been noted. Clinical trials of antiviral agents, such as interferons, are in progress, while new therapies such as viral vaccines, recombinant virus and virus receptors, are in preclinical development. Whereas immunosuppression with corticosteroids or cyclosporin is ineffective, immunosuppressors that do not promote viral replication, such as FTY720, and immunomodulation by interleukin-10, are promising new approaches. Inhibition of nuclear factor-κB, angiotensin II and endothelin effectively suppresses inflammation in experimental viral myocarditis. Embryonic stem cell therapy has been demonstrated to be beneficial; however, this requires further investigation.

Mycophenolate mofetil prevents the development of experimental autoimmune myocarditis

Experimental autoimmune myocarditis (EAM) is characterized by the appearance of multinucleated giant cells. EAM leads to severe myocardial damage and is a useful model of human giant cell myocarditis. We investigated whether mycophenolate mofetil (MMF), which is a potent immunosuppressant, prevents the development of myocarditis in a rat EAM model, and focused on the role of osteopontin (OPN) in the pathogenesis of this disorder. Adult Lewis rats were immunized with porcine cardiac myosin to establish EAM. The early MMF treatment completely prevented the development of EAM, and the late MMF treatment was also effective even against established EAM. Echocardiogram demonstrated that left ventricular function was also improved by the treatment with MMF. Real-time RT-PCR analysis showed that both early and late MMF treatments significantly inhibited myocarditis-induced OPN mRNA expression in the heart. Immunohistochemistry revealed that OPN expression was prominent in the myocardium on day 14, whereas expression was observed in the infiltrated macrophages on day 21. Mycophenolic acid (MPA) did inhibit agonist-induced OPN expression in cultured cardiomyocytes. These results show the therapeutic potential of MMF for autoimmune myocarditis and provide new insights into the pathogenesis of this disease.

Outcomes for children with acute myocarditis

The optimum treatment for myocarditis in children is unknown. We present outcomes for this disease as seen in a large series of children. Thus, we identified all children seen with myocarditis at Children's Hospital of Pittsburgh since 1985, including only those with biopsy-proven myocarditis, or cardiac dysfunction and proof of concomitant cardiotropic viral infection. Outcomes were defined as complete recovery, incomplete recovery, and death or transplantation. We identified 41 patients, 37 proven by histology, and 4 patients who were too unstable for biopsy but had proof of viral infection. Of the group, 27 (66%) made a complete recovery, 4 (10%) had incomplete recovery, and 10 (24%) either died (5) or underwent transplantation (5). The median time to death or transplantation was 8.4 months, with a range from 1 day to 49 months. Steroids had been administered to 16 patients, of whom 10 made a complete recovery, 2 an incomplete recovery, 2 died, and 2 were transplanted. Intravenous immune globulin was given in isolation to one patient, who made a complete recovery, and to 18 in combination with steroids, of whom 12 made a complete recovery, 2 an incomplete recovery, 2 died, and 2 were transplanted. The remaining 6 patients received neither steroids nor intravenous immune globulin, and of these, 4 made a complete recovery, 1 was transplanted, and 1 died. Freedom from death or transplantation was 81% at 1 year, and 74% at 5 years, with no difference between the modes of treatments. The median time to recovery of function was also comparable between the groups. Thus, in our patients, treatment with intravenous immune globulin appeared to confer no advantage to steroid therapy alone. These data emphasise the need for randomised trials to assess the efficacy of current treatments, as well as that of new therapies.

Incidence and follow-up of inflammatory cardiac complications after smallpox vaccination11The views expressed in this study are those of the authors and do not reflect the official policy or position of the U.S. government

OBJECTIVES

The purpose of this study was to assess the follow-up of patients with vaccinia-associated myocarditis.

BACKGROUND

With the threat of biological warfare, the U.S. Department of Defense resumed a program for widespread smallpox vaccinations on December 13, 2002. One-year afterwards, there has been a significant increase in the occurrence of myocarditis and pericarditis among those vaccinated.

METHODS

Cases were identified through sentinel reporting to military headquarters, systematic surveillance, and spontaneous reports.

RESULTS

A total of 540,824 military personnel were vaccinated with a New York City Board of Health strain of vaccinia from December 2002 through December 2003. Of these, 67 developed myopericarditis at 10.4 +/- 3.6 days after vaccination. The ST-segment elevation was noted in 57%, mean troponin on admission was 11.3+/- 22.7 ng/dl, and peak cardiac enzymes were noted within 8 h of presentation. On follow-up of 64 patients (96%) at a mean of 32 +/- 16 weeks, all patients had objective normalization of echocardiography, electrocardiography, laboratory testing, graded exercise testing, and functional status; 8 (13%) reported atypical, non-limiting persistent chest discomfort.

CONCLUSIONS

Post-vaccinial myopericarditis should be considered in patients with chest pain within 30 days after smallpox vaccination. Normalization of echocardiography, electrocardiography, and treadmill testing is expected, and nearly all patients have resolution of chest pain on follow-up.

Suppression of cytokines and nitric oxide production, and protection against lethal endotoxemia and viral myocarditis by a new NF-κB inhibitor

BACKGROUND

Nuclear factor kappa B (NF-kappaB) is activated by several factors, which increase the inflammatory response, and this activation, in turn, leads to the expression of several genes such as cytokines, and may play an important role in cardiovascular diseases.

AIMS

The aim of the study is to examine the effect of SUN C8079, a newly synthesized NF-kappaB inhibitor in vitro and in vivo.

METHODS

We examined the effects of SUN C8079 on the transcriptional responses of NF-kappaB, on activation of NF-kappaB in electrophoretic mobility shift assay, and on the gene expressions of tumor necrosis factor (TNF)-alpha and iNOS. We also studied effects of SUN C8079 on lethal endotoxemia and viral myocarditis in mice.

RESULTS

SUN C8079 inhibited the lipopolysaccharide (LPS)-induced expression of the genes of TNF-alpha and iNOS by inhibiting the activation of NF-kappaB in vitro. SUN C8079 inhibited the systemic release of TNF-alpha and improved mortality in LPS-treated mice. In addition to protecting mice against lethal endotoxemia, SUN C8079 prevented the development of myocarditis due to the encephalomyocarditis virus (EMCV), and inhibited the expressions of proinflammatory cytokines and the iNOS gene in cardiac tissues.

CONCLUSION

These findings suggest that the activation of NF-kappaB plays an important role in the pathogenesis of endotoxemia and viral myocarditis, and that the NF-kappaB inhibitor, SUN C8079, may be therapeutic in these disorders.

Mycophenolate mofetil inhibits the development of Coxsackie B3-virus-induced myocarditis in mice

Background

Viral replication as well as an immunopathological component are assumed to be involved in the development of coxsackie B virus (CBV)-induced myocarditis. We observed that mycophenolic acid (MPA), the active metabolite of the immunosuppressive agent mycophenolate mofetil (MMF), inhibits coxsackie B3 virus (CBV3) replication in primary Human myocardial fibroblasts. We therefore studied whether MMF, which is thus endowed with a direct antiviral as well as immunosuppressive effect, may prevent CBV-induced myocarditis in a murine model.

Results

Four week old C3H-mice were infected with CBV3 and received twice daily, for 7 consecutive days (from one day before to 5 days post-virus inoculation) treatment with MMF via oral gavage. Treatment with MMF resulted in a significant reduction in the development of CBV-induced myocarditis as assessed by morphometric analysis, i.e. 78% reduction when MMF was administered at 300 mg/kg/day (p < 0.001), 65% reduction at 200 mg/kg/day (p < 0.001), and 52% reduction at 100 mg/kg/day (p = 0.001). The beneficial effect could not be ascribed to inhibition of viral replication since titers of infectious virus and viral RNA in heart tissue were increased in MMF-treated animals as compared to untreated animals.

Conclusion

The immunosuppressive agent MMF results in an important reduction of CBV3-induced myocarditis in a murine model.

Antiinflammatory therapy in myocarditis

Acute viral myocarditis progresses through several stages, including acute viral infection, autoimmunity, and dilated cardiomyopathy. Recent studies have identified an important role for the myocardial inflammatory response during the initial phases of acute viral myocarditis. In this review, we discuss new insights into the innate host response to viral myocarditis and the various therapeutic strategies that have been attempted in managing the deleterious consequences of the myocardial inflammatory response in acute viral myocarditis.

Immunosuppressive therapy for active lymphocytic myocarditis: virological and immunologic profile of responders versus nonresponders

BACKGROUND

The beneficial effect of immunosuppressive treatment on myocarditis is still controversial, possibly because the immunologic and virological profile of potential candidates is largely unknown.

METHODS AND RESULTS

Out of 652 biopsied patients, 112 had a histological diagnosis of active lymphocytic myocarditis; 41 of these 112 patients were characterized by progressive heart failure despite conventional therapy and were treated with prednisone and azathioprine for 6 months. All were resubmitted to cardiac catheterization, angiography, and endomyocardial biopsy at 1 and 6 months and followed-up for 1 year. A total of 21 patients responded with prompt improvement in left ventricular ejection fraction from 25.7+/-4.1% to 47.1+/-4.4% and showed evidence of healed myocarditis at control biopsy. Conversely, 20 patients failed to respond and showed a histological evolution toward dilated cardiomyopathy: 12 remained stationary, 3 underwent cardiac transplantation, and 5 died. We retrospectively performed a polymerase chain reaction on frozen endomyocardial tissue for the most common cardiotropic viruses and assessed circulating serum cardiac autoantibodies. Viral genomes were present in biopsy specimens of 17 nonresponders (85%), including enterovirus (n=5), Epstein-Barr virus (n=5) adenovirus (n=4), both adenovirus and enterovirus (n=1), influenza A virus (n=1), parvovirus-B19 (n=1), and in 3 responders, who were all positive for hepatitis C virus. Cardiac autoantibodies were present in 19 responders (90%) and in none of the nonresponders.

CONCLUSIONS

In patients with active lymphocytic myocarditis, those with circulating cardiac autoantibodies and no viral genome in the myocardium are the most likely to benefit from immunosuppression. The beneficial effect of immunosuppression in hepatitis C virus myocarditis suggests a relevant immunomediated component of damage.

Diagnosis and management of pediatric myocarditis

Myocarditis is an insidious inflammatory disorder of the myocardium. As a clinical entity, it has been recognized for two centuries, but it defies traditional diagnostic tests. A greater understanding of the immune response underlying the pathobiology of the disorder can lead to a more rational therapeutic approach. The presentation, course and therapeutic options appear to be different in the pediatric compared with the adult population. An understanding of the difference between fulminant and acute progressive myocarditis has led to successful treatment strategies. A variety of new therapies are available, including antiviral agents, immunosuppression, and modulation of the biological response to inflammation. The specific question for patients with myocarditis is whether regimens designed to reduce or eliminate inflammation can provide clinical benefits compared with conventional heart failure therapy. This review highlights pathological mechanisms, modalities of diagnosis, and novel therapies which may improve outcomes.

Innovative drug treatments for viral and autoimmune myocarditis

Myocarditis is a common cause of cardiomyopathy and is thought to account for 25% of all cases in humans. Unfortunately, the disease is difficult to detect clinically before a myopathic process ensues. Management of myocarditis-induced heart failure includes the standard regimen of diuretics, digoxin, angiotensin-converting enzyme inhibitors, angiotensin-II receptor blockers, and beta-adrenergic blockers. The management of myocarditis itself is dependent on the etiology of the illness. Treatments that are currently under investigation include immunosuppressants, nonsteroidal antiinflammatory agents, immunoglobulins, immunomodulation, antiadrenergics, calcium-channel blockers, angiotensin-converting enzyme inhibitors, nitric oxide inhibitors (e.g., aminoguanidine), and antivirals. Despite advances in treatment, more work needs to be done in the early detection of myocarditis. Additionally, better means need to be established for distinguishing between viral and noninfectious autoimmune forms of the disease, so that appropriate treatment can be instituted.

Therapeutic effects of FTY720, a new immunosuppressive agent, in a murine model of acute viral myocarditis

OBJECTIVES

This study examines the efficacy of FTY720 (FTY), a new immunosuppressor, in the treatment of acute viral myocarditis in a murine model.

BACKGROUND

Immunosuppressive agents have no proven therapeutic efficacy in experimental or clinical myocarditis.

METHODS

Encephalomyocarditis virus was inoculated i.p. in DBA/2 mice on day 0. Postinoculation treatment consisted of FTY 10 mg/kg/day p.o. (FTY group), or cyclosporine A (CsA) 40 mg/kg/day p.o. (CsA group) or distilled water p.o. only (control group). Survival until day 14, as well as cardiac histopathology, virus concentrations, cytokines (interleukin [IL]-2, IL-12, interferon [IFN]-gamma and tumor necrosis factor [TNF]-alpha) and nitric oxide (NO) on day 5 were examined.

RESULTS

In the control and CsA groups, all mice died within 10 and 7 days, respectively. However, in the FTY group, 27% of the animals survived up to day 14. Compared with the control group, 1) histological scores were significantly lower in the FTY group but unchanged in the CsA group; 2) virus concentration was significantly higher in the CsA group but not in the FTY group; 3) expressions of IL-2, IL-12 and IFN-gamma in the heart were suppressed in both the FTY and CsA groups, though suppression was weaker in the FTY group; 4) TNF-alpha and NO were significantly increased in the CsA group but not in the FTY group.

CONCLUSIONS

FTY720 had a significant therapeutic effect in acute experimental myocarditis without inducing excessive virus replication. This report is the first to describe a beneficial effect by an immunosuppressive agent in the treatment of acute viral myocarditis.

Resuscitation from fulminant myocarditis associated with refractory ventricular fibrillation

Resuscitation was possible in a case of fulminant myocarditis with refractory ventricular fibrillation (Vf) using a percutaneous cardiopulmonary support system (PCPS). A 46-year old Japanese man suddenly experienced cardiopulmonary dysfunction shortly after the onset of flu symptoms, was promptly diagnosed as having fulminant myocarditis and PCPS was immediately initiated. On the second day in the hospital, refractory Vf occurred, which lasted for approximately 2h despite repeated efforts to terminate it. Finally, a large dose of steroids was administered. From the third day of hospitalization and onwards, the Vf disappeared totally. The patient completely recovered from such a serious state in 6 months. During the following 3 years, he has had no clinical symptoms of worsening. As in this case demonstrates, most myocarditis is curable and invasive measures are very helpful in rescuing patients from the fulminant type with refractory Vf.

Clinical outcomes of acute myocarditis in childhood

OBJECTIVE

To describe clinical outcomes of a paediatric population with histologically confirmed lymphocytic myocarditis.

DESIGN

A retrospective review between November 1984 and February 1998.

SETTING

A major paediatric tertiary care hospital.

PATIENTS

36 patients with histologically confirmed lymphocytic myocarditis.

MAIN OUTCOME MEASURES

Survival, cardiac transplantation, recovery of ventricular function, and persistence of dysrhythmias.

RESULTS

Freedom from death or cardiac transplantation was 86% at one month and 79% after two years. Five deaths occurred within 72 hours of admission, and one late death at 1.9 years. Extracorporeal membrane oxygenation support was used in four patients, and three patients underwent heart replacement. 34 patients were treated with intravenous corticosteroids. In the survivor/non-cardiac transplantation group (n = 29), the median follow up was 19 months (range 1.2-131.6 months), and the median period for recovery of a left ventricular ejection fraction to > 55% was 2.8 months (range 0-28 months). The mean (SD) final left ventricular ejection and shortening fractions were 66 (9)% and 34 (8)%, respectively. Two patients had residual ventricular dysfunction. No patient required antiarrhythmic treatment. All survivors reported no cardiac symptoms or restrictions in physical activity.

CONCLUSIONS

Our experience documents good outcomes in paediatric patients presenting with acute heart failure secondary to acute lymphocytic myocarditis treated with immunosuppression. Excellent survival and recovery of ventricular function, with the absence of significant arrhythmias, continued cardiac medications, or restrictions in physical activity were the normal outcomes.

From myocarditis to cardiomyopathy: mechanisms of inflammation and cell death: learning from the past for the future

A progression from viral myocarditis to dilated cardiomyopathy has long been hypothesized, but the actual extent of this progression has been uncertain. However, a causal link between viral myocarditis and dilated cardiomyopathy has become more evident than before with the tremendous developments in the molecular analyses of autopsy and endomyocardial biopsy specimens, new techniques of viral gene amplification, and modern immunology. The persistence of viral RNA in the myocardium beyond 90 days after inoculation, confirmed by the method of polymerase chain reaction, has given us new insights into the pathogenesis of dilated cardiomyopathy. Moreover, new knowledge of T-cell-mediated immune responses in murine viral myocarditis has contributed a great deal to the understanding of the mechanisms of ongoing disease processes. Apoptotic cell death may provide the third concept to explain the pathogenesis of dilated cardiomyopathy, in addition to persistent viral RNA in the heart tissue and an immune system-mediated mechanism. Beneficial effects of alpha1-adrenergic blocking agents, carteolol, verapamil, and ACE inhibitors have been shown clinically and experimentally in the treatment of viral myocarditis and dilated cardiomyopathy. Antiviral agents should be more extensively investigated for clinical use. The rather discouraging results obtained to date with immunosuppressive agents in the treatment of viral myocarditis indicated the importance of sparing neutralizing antibody production, which may be controlled by B cells, and raised the possibility of promising developments in immunomodulating therapy.

A new scoring system to predict the efficacy of steroid therapy for patients with active myocarditis--a retrospective study

The efficacy of steroid therapy for active myocarditis is controversial, so a new scoring system was constructed based on 6 clinical parameters: (1) the mode of onset of the disease; (2) complications of immune-related systemic disorders; (3) evidence of viral infection; (4) the population of infiltrating inflammatory cells; (5) the appearance of multinucleated giant cells in endomyocardial biopsy specimens; and (6) the duration of active myocarditis. Points from -2 to +2 were assigned to each parameter and the total score was calculated from the 6 parameters. Twenty-one patients with clinically suspected myocarditis, who had been admitted to hospital from 1987, were retrospectively analyzed by this scoring system. Sixteen patients were treated without corticosteroids at presentation, and 5 patients were treated by conventional methods with adjunctive use of corticosteroids. In 10 patients of the non-steroid group myocarditis improved and their mean score was -4.8 at presentation. In 6 patients of the non-steroid group, myocarditis and cardiac symptoms persisted after initial therapy, and their score at presentation was -0.8. In 2 patients of the steroid group myocarditis improved after initial therapy and their score was +2. In 2 other patients of the steroid group, myocarditis and cardiac symptoms persisted and their score was +3. Another patient of the steroid group died from congestive heart failure and his score was -5 at presentation. In 8 of 9 patients with persistent myocarditis, the secondary phase therapy was challenged. Seven patients were treated with corticosteroids and 6 patients improved. Their score at the secondary phase was +2.5. Overall, non-steroid conventional treatment was successful in patients with the scores from -5 to -4, and steroid therapy succeeded in patients with scores from 0 to +6. Although this is a retrospective study, this scoring system is able to predict the efficacy of steroid therapy in patients with clinically suspected active myocarditis.

Innovative drug treatments for viral and autoimmune myocarditis

Myocarditis has been shown to be a common cause of cardiomyopathy and is believed to account for 25% of all cases in human beings. Unfortunately, the disease is difficult to detect before a myopathic process ensues. Treatment of myocarditis-induced heart failure includes the standard regimen of diuretics, digoxin, angiotensin-converting enzyme inhibitors, and currently, beta-adrenergic blockers. Treatment of myocarditis itself is dependent on the etiology of the illness. Treatments under investigation include immunosuppressants, nonsteroidal antiinflammatory agents, immunoglobulins, immunomodulation, antiadrenergics, calcium-channel blockers, angiotensin-converting enzyme inhibitors, nitric oxide inhibition (e.g., aminoguanidine), and antiviral agents. Despite advances in treatment, more work needs to be done in the early detection of myocarditis. Additionally, better means need to be established for distinguishing between viral and autoimmune forms of the disease, so that appropriate treatment can be instituted.

Intravenous immune globulin in the therapy of myocarditis and acute cardiomyopathy

BACKGROUND

Although an autoimmune pathogenesis has been postulated for dilated cardiomyopathy, immunosuppressive therapy has not been shown to be effective in clinical trials. Immune modulatory therapy with immune globulin is an effective therapy for Kawasaki disease in children, and recent data suggest that it improves ventricular function in children with new-onset dilated cardiomyopathies. The role of immune globulin therapy in adults with this disorder has not previously been evaluated.

METHODS AND RESULTS

Ten patients were treated with high-dose intravenous immune globulin infusions (2 g/kg). All were hospitalized with NYHA class III to IV heart failure, left ventricular ejection fraction (LVEF) < 0.40, and symptoms for < 6 months at the time of presentation. One patient died before the completion of therapy. The remaining 9 were discharged, and LVEF was reassessed 12 months after therapy. LVEF improved from 0.24 +/- 0.02 (mean +/- SEM) at baseline to 0.41 +/- 0.04 at follow-up (P = .003). All 9 patients improved functionally to NYHA class I to II, and there have been no subsequent hospitalizations for heart failure during the course of follow-up.

CONCLUSIONS

In this series of patients with new-onset dilated cardiomyopathy treated with high-dose immune globulin, LVEF improved 17 EF units. The effectiveness of intravenous immune globulin therapy in this disorder should be evaluated in a randomized, multicenter trial.

Beneficial effects of amlodipine in a murine model of congestive heart failure induced by viral myocarditis. A possible mechanism through inhibition of nitric oxide production

BACKGROUND

Although calcium channel blockers have not been shown to be beneficial for the treatment of patients with heart failure, a recent clinical trial demonstrated a favorable effect of amlodipine on the survival of patients with heart failure resulting from nonischemic dilated cardiomyopathy. We investigated the effects of amlodipine on a murine model of congestive heart failure induced by the M variant of encephalomyocarditis virus (EMCV).

METHODS AND RESULTS

Four-week-old male DBA/2 mice were inoculated with EMCV and administered amlodipine, diltiazem, or vehicle PO for 2 weeks. The heart weight-to-body weight ratio and the histopathological grades of myocardial lesions were significantly lower and survival was significantly increased in the amlodipine-treated group (P < .01, P < .05, and P < .05, respectively) than in the control group. In vitro, amlodipine added to murine J774A.1 macrophages concomitant with EMCV inhibited nitrite formation in a concentration-dependent manner, but diltiazem did not. Furthermore, NG-monomethyl-L-arginine, an inhibitor of NO synthesis, decreased myocardial lesions significantly in this murine model. Immunohistochemistry revealed that the number of cells stained with antibody against an inducible NO synthase decreased significantly in the amlodipine-treated group compared with that in the control group (P < .01).

CONCLUSIONS

Amlodipine appears to have a protective effect against myocardial injury in this animal model of congestive heart failure. The therapeutic effect of amlodipine may be in part resulting from inhibition of overproduction of NO.

Effects of levamisole, an immunomodulator, upon murine encephalomyocarditis virus myocarditis

To test the therapeutic efficacy of levamisole, 5-week-old DBA/2 mice were inoculated intraperitoneally with 10 plaque-forming units of encephalo-myocarditis virus. Levamisole (2.5 mg/kg/per day) was administered intraperitoneally daily, starting simultaneously with the virus inoculation, in experiment I for 14 days, and daily on days 14 to 28 in experiment II in mice that survived to 14 days after virus inoculation. In experiment I, survival was higher, the severity of myocarditis was less, and myocardial virus titers were lower in treated than in untreated animals. In experiment II, levamisole was not effective. No significant changes in serum neutralizing antibody titers occurred in either experiment. Furthermore, levamisole prevented associated lymphoid organ atrophy induced by the virus infection. An additional in vitro study revealed the absence of anti-viral activity of the drug. Thus, levamisole may have favorable effects upon encephalomyocarditis virus myocarditis by preventing the virus-induced lymphoid organ atrophy and reducing myocardial virus replication in the acute stage.

Therapy with immunoglobulin suppresses myocarditis in a murine coxsackievirus B3 model. Antiviral and anti-inflammatory effects

BACKGROUND

The treatment of some inflammatory diseases (eg, Kawasaki disease) with immunoglobulin has been demonstrated to be effective. Accordingly, to elucidate the mechanism underlying such actions of immunoglobulin, we examined its effects on murine coxsackievirus B3 (CB3) myocarditis.

METHODS AND RESULTS

An in vitro study showed dose-dependent suppression of CB3 by immunoglobulin. Immunoglobulin 1 g.kg-1.d-1 IP was administered to CB3-infected C3H/He mice daily for 2 weeks, beginning simultaneously with virus inoculation in experiment 1 and on day 14 after virus inoculation in experiment 2. In both experiments, survival was higher in treated than in control mice; at the time of death, inflammatory also were reduced. Notably, in experiment 1, immunoglobulin administration completely suppressed the development of myocarditis. Serum-neutralizing antibody titers in the treated mice were significantly higher than those in untreated mice in experiment 1 but not in experiment 2. The circulating antibodies of the treated mice were primarily of exogenous origin in experiment 1 and of exogenous and endogenous origins in experiment 2. The analysis of splenic lymphocyte subsets revealed a marked decrease of the B cell population in the treated mice.

CONCLUSIONS

Immunoglobulin therapy completely suppressed acute CB3 myocarditis by transferring the neutralizing antibody into the host in the acute viremic stage and induced an anti-inflammatory effect in the subsequent aviremic stage; the reduction of the splenic B-cell population may be closely associated with an anti-inflammatory effect.

Effects of 15-deoxyspergualin on experimental autoimmune giant cell myocarditis of the rat

BACKGROUND

The benefits of immunosuppressive therapy for human myocarditis are controversial. The effects of a new immunosuppressant agent, 15-deoxyspergualin (DSG), on rats with experimental autoimmune myocarditis (EAM), an animal model of human giant cell myocarditis, were examined.

METHODS AND RESULTS

Lewis rats were immunized with cardiac myosin in Freund's complete adjuvant on day 0. In the first experiment, the effective doses of DSG required to prevent EAM were investigated. Rats were placed into one of five groups: the control group (A) was administered saline from days 1 to 10; group B, 0.3 mg/kg per day of DSG; group C, 1.0 mg/kg per day of DSG; group D, 3.0 mg/kg per day of DSG, and group E, 10.0 mg/kg per day of DSG. Rats were killed on day 28. The heart weight/body weight ratios of the rats of groups D and E were significantly lower than that of the control group. Macroscopic and microscopic scores for myocarditis decreased in groups D and E. In the next experiment, the effects of delayed administration of DSG in preventing autoimmune myocarditis were studied. Two groups of rats received 3.0 and 10.0 mg/kg per day of DSG from days 6 to 15, respectively. Two other groups of rats received the same doses of DSG from days 11 to 20. No preventive effect of delayed DSG treatment was observed. The effects of long-term, delayed initiation therapy then were evaluated. Rats were administered 10.0 mg/kg per day of DSG from days 6 to 25. The heart weight/body weight ratio and macroscopic and microscopic scores of the rats so treated significantly decreased compared with the controls.

CONCLUSIONS

It was demonstrated that DSG can prevent the development of cardiac myosin-induced autoimmune myocarditis.

Treatment of virus-induced myocardial injury with a novel immunomodulating agent, vesnarinone. Suppression of natural killer cell activity and tumor necrosis factor-alpha production

Controversy still exists concerning the therapy for viral myocarditis which manifests a wide variety of clinical symptoms. Vesnarinone, a quinolinone derivative that was developed as a positive inotropic agent with complex actions, including phosphodiesterase inhibition and cation channel modification, has recently been confirmed to improve the prognosis of patients with chronic heart failure. However, the precise mechanism of this beneficial effect is not yet clearly understood. In this study, using a murine model of acute viral myocarditis resulting from encephalomyocarditis virus infection, survival and myocardial damage were markedly improved by treatment with vesnarinone. In contrast, survival was not improved by treatment with amrinone, a phosphodiesterase inhibitor. Although vesnarinone did not inhibit viral replication or protect myocytes from viral direct cell injury, it did inhibit the increase in natural killer cell activity after viral infection. On the other hand, amrinone failed to inhibit natural killer cell activity. Both vesnarinone and amrinone suppressed the production of tumor necrosis factor-alpha. Therefore, we postulate that vesnarinone exerted its beneficial effects through an inhibition of natural killer cell activity, and that it serves as an immunomodulator providing new therapeutic possibilities for the treatment of viral myocarditis and/or immunological disorders.