Autoimmune Myocarditis, Old Dogs and New Tricks.

Autoimmunity significantly contributes to the pathogenesis of myocarditis, underscored by its increased frequency in autoimmune diseases such as systemic lupus erythematosus and polymyositis. Even in cases of myocarditis caused by viral infections, dysregulated immune responses contribute to pathogenesis. However, whether triggered by existing autoimmune conditions or viral infections, the precise antigens and immunologic pathways driving myocarditis remain incompletely understood. The emergence of myocarditis associated with immune checkpoint inhibitor therapy, commonly used for treating cancer, has afforded an opportunity to understand autoimmune mechanisms in myocarditis, with autoreactive T cells specific for cardiac myosin playing a pivotal role. Despite their self-antigen recognition, cardiac myosin-specific T cells can be present in healthy individuals due to bypassing the thymic selection stage. In recent studies, novel modalities in suppressing the activity of pathogenic T cells including cardiac myosin-specific T cells have proven effective in treating autoimmune myocarditis. This review offers an overview of the current understanding of heart antigens, autoantibodies, and immune cells as the autoimmune mechanisms underlying various forms of myocarditis, along with the latest updates on clinical management and prospects for future research.

Genome-wide association study of BNT162b2 vaccine-related myocarditis identifies potential predisposing functional areas in Hong Kong adolescents.

Vaccine-related myocarditis associated with the BNT162b2 vaccine is a rare complication, with a higher risk observed in male adolescents. However, the contribution of genetic factors to this condition remains uncertain. In this study, we conducted a comprehensive genetic association analysis in a cohort of 43 Hong Kong Chinese adolescents who were diagnosed with myocarditis shortly after receiving the BNT162b2 mRNA COVID-19 vaccine. A comparison of whole-genome sequencing data was performed between the confirmed myocarditis cases and a control group of 481 healthy individuals. To narrow down potential genomic regions of interest, we employed a novel clustering approach called ClusterAnalyzer, which prioritised 2,182 genomic regions overlapping with 1,499 genes for further investigation. Our pathway analysis revealed significant enrichment of these genes in functions related to cardiac conduction, ion channel activity, plasma membrane adhesion, and axonogenesis. These findings suggest a potential genetic predisposition in these specific functional areas that may contribute to the observed side effect of the vaccine. Nevertheless, further validation through larger-scale studies is imperative to confirm these findings. Given the increasing prominence of mRNA vaccines as a promising strategy for disease prevention and treatment, understanding the genetic factors associated with vaccine-related myocarditis assumes paramount importance. Our study provides valuable insights that significantly advance our understanding in this regard and serve as a valuable foundation for future research endeavours in this field.

STAT1 regulates neutrophil gelatinase B-associated lipocalin induction in influenza-induced myocarditis.

Influenza is a significant public health and economic threat around the world. Epidemiological studies have demonstrated a close association between influenza pandemics and cardiovascular mortality. Moreover, it has been shown that there is a decrease in cardiovascular mortality in high-risk patients following vaccination with the influenza vaccine. Here, we have investigated the role of anti-viral STAT1 signaling in influenza-induced myocarditis. Wild-type mice (C57BL/6) were infected with either influenza A/PR/8/34 or control, and cellular response and gene expression analysis from the heart samples were assessed 7 days later. The expression of interferon response genes STAT1, STAT2, Mx1, OASL2, ISG15, chemokines CCL2, CCL3, CXCL9 and CXCL10, and the frequency of neutrophils (CD45+CD11b+Ly6G+) and CD4+ T cells (CD45+CD4+) were all significantly increased in influenza-infected mice when compared to vehicle controls. These data suggest that influenza infection induces interferons, inflammatory chemokines, and cellular recruitment during influenza infection. We further investigated the role of STAT1 in influenza-induced myocarditis. The frequency of neutrophils and the levels of lipocalin 2 were significantly increased in STAT1-/- mice when compared to WT controls. Finally, we investigated the role of Lcn2 in viral-induced myocarditis. We found that in the absence of Lcn2, there was preserved cardiac function in Lcn2-/- mice when compared to WT controls. These data suggest that the absence of Lcn2 is cardioprotective during viral-induced myocarditis.

[A rare case of recurrent myocarditis revealing pheochromocytoma]. / Un rare cas de myocardite récurrente révélant un phéochromocytome.

Pheochromocytoma is a rare neuroendocrine tumor characterized by overproduction of catecholamines. The overproduction of catecholamines leads to cardiac remodeling which manifests in several forms ranging from Takotsubo to dilated cardiomyopathy. Studies suggest that pheochromocytoma-induced cardiomyopathy can take various forms depending on the duration of catecholamine exposure. Myocarditis is a fairly rare presentation of cardiac manifestations of pheochromocytoma which are mainly dominated by Takotsubo and dilated cardiomyopathies. We report a rare case of recurrent myocarditis in a young 37-year-old patient revealing the diagnosis of adrenal pheochromocytoma. Through this case and through a review of the literature we will take stock of the epidemiology of cardiac involvement in pheochromocytoma, mainly cardiomyopathies, and we will take stock of the value of diagnosis and early management in improving the prognosis of patients.

Granulomatous Myocarditis Caused by Candida Spp Infection in a Spontaneously Diabetic Torii Rat.

Background: Myocarditis refers to myocardial inflammation with necrosis caused by non-infectious of infectious agents such as bacteria, fungi, or drugs. Candida is known to cause myocarditis in healthy and immunocompromised individuals. Diabetes mellitus causes chronic hyperglycemia due to impaired secretion or hypofunction of insulin, induces a compromised state, and increases the risk of contracting various infections. Objective: We report a case of granulomatous myocarditis caused by Candida in a Spontaneously Diabetic Torii rat, a non-obese diabetic model. Case report: A male SDT rat, 61 weeks of age, was housed in conventional environment. The rat was provided a commercial diet and tap water ad libitum. The heart was sampled and prepared the specimen of hematoxylin-and-eosin-, Sirius-red-, Giemsa-, Grocott-stain. Histologically, formation of large granulation tissue was observed in the left ventricular wall. A center of the foci showed necrosis. Moreover, inflammatory cells infiltration and fibrous component were increased surrounding the foci and between myocardial cells. A Grocott and Giemsa staining-positive cell masses occasionally appearing in the foci were considered to be Candida because of their characteristic form. Conclusion: The development and progression of myocarditis were potentially related to a diabetes-induced compromised state.

Characterization of Brighton Collaboration criteria for myocarditis and pericarditis following COVID-19 vaccine in Korean adolescents.

BACKGROUND: Vaccines are vital for public health, but concerns about adverse effects, particularly myocarditis and pericarditis linked to COVID-19 vaccines-, persist. This study investigates the application of Brighton Collaboration case definition to national vaccine safety data related to post-COVID-19 vaccine myo/pericarditis, utilizing claims under the Korea National Vaccine Injury Compensation Program (NIVCP). METHODS: This study analyzed 190 medical records of individuals who claimed to have developed myo/pericarditis after receiving the COVID-19 vaccine, as reported to the NVICP between specified dates, categorizing cases based on the Brighton criteria for myocarditis or pericarditis. RESULTS: Between 2021-2022, NVICP received 190 cases meeting the Brighton criteria for myocarditis or pericarditis at levels 1, 2, or 3. Most cases fell into Level 2 (70%), followed by Level 1 (29%), and one at Level 3 (1%), with Level 1 cases showing a higher hospitalization rate (87.3%) and a notable proportion requiring admission to the Intensive Care Unit (25.5%). Chest pain and Troponin-I/T elevation were common findings in Level 1 cases, while Level 2 cases exhibited similar patterns but at a slightly lower frequency. Electrocardiogram and echocardiography findings differed between the two levels. CONCLUSION: The Brighton Collaboration case definition proved valuable for classifying and assessing AEFI data, enhancing our understanding of the potential relationship between myocarditis and the COVID-19 vaccine.

The central role of natural killer cells in mediating acute myocarditis after mRNA COVID-19 vaccination.

BACKGROUND: Vaccine-related acute myocarditis is recognized as a rare and specific vaccine complication following mRNA-based COVID-19 vaccinations. The precise mechanisms remain unclear. We hypothesized that natural killer (NK) cells play a central role in its pathogenesis. METHODS: Samples from 60 adolescents with vaccine-related myocarditis were analyzed, including pro-inflammatory cytokines, cardiac troponin T, genotyping, and immunophenotyping of the corresponding activation subsets of NK cells, monocytes, and T cells. Results were compared with samples from 10 vaccinated individuals without myocarditis and 10 healthy controls. FINDINGS: Phenotypically, high levels of serum cytokines pivotal for NK cells, including interleukin-1ß (IL-1ß), interferon α2 (IFN-α2), IL-12, and IFN-γ, were observed in post-vaccination patients with myocarditis, who also had high percentage of CD57+ NK cells in blood, which in turn correlated positively with elevated levels of cardiac troponin T. Abundance of the CD57+ NK subset was particularly prominent in males and in those after the second dose of vaccination. Genotypically, killer cell immunoglobulin-like receptor (KIR) KIR2DL5B(-)/KIR2DS3(+)/KIR2DS5(-)/KIR2DS4del(+) was a risk haplotype, in addition to single-nucleotide polymorphisms related to the NK cell-specific expression quantitative trait loci DNAM-1 and FuT11, which also correlated with cardiac troponin T levels in post-vaccination patients with myocarditis. CONCLUSION: Collectively, these data suggest that NK cell activation by mRNA COVID-19 vaccine contributed to the pathogenesis of acute myocarditis in genetically and epidemiologically vulnerable subjects. FUNDING: This work was funded by the Hong Kong Collaborative Research Fund (CRF) 2020/21 and the CRF Coronavirus and Novel Infectious Diseases Research Exercises (reference no. C7149-20G).

Exploring the Role of Platelets in Virus-Induced Inflammatory Demyelinating Disease and Myocarditis.

Theiler's murine encephalomyelitis virus (TMEV) infection has been used as a mouse model for two virus-induced organ-specific immune-mediated diseases. TMEV-induced demyelinating disease (TMEV-IDD) in the central nervous system (CNS) is a chronic inflammatory disease with viral persistence and an animal model of multiple sclerosis (MS) in humans. TMEV infection can also cause acute myocarditis with viral replication and immune cell infiltration in the heart, leading to cardiac fibrosis. Since platelets have been reported to modulate immune responses, we aimed to determine the role of platelets in TMEV infection. In transcriptome analyses of platelets, distinct sets of immune-related genes, including major histocompatibility complex (MHC) class I, were up- or downregulated in TMEV-infected mice at different time points. We depleted platelets from TMEV-infected mice by injecting them with platelet-specific antibodies. The platelet-depleted mice had significantly fewer viral antigen-positive cells in the CNS. Platelet depletion reduced the severities of TMEV-IDD and myocarditis, although the pathology scores did not reach statistical significance. Immunologically, the platelet-depleted mice had an increase in interferon (IFN)-γ production with a higher anti-TMEV IgG2a/IgG1 ratio. Thus, platelets may play roles in TMEV infection, such as gene expression, viral clearance, and anti-viral antibody isotype responses.

Risk of myocarditis after three doses of COVID-19 mRNA vaccines in the United States, 2020-2022: A self-controlled case series study.

AIM: Myocarditis is a recognized safety concern following COVID-19 mRNA vaccination. However, there is limited research quantifying the risk associated with the third dose or comparing the risk between the three doses. The US Vaccine Adverse Event Reporting System (VAERS) is a passive surveillance system that monitors rare adverse events after US-licensed vaccination. However, studies analyzing VAERS data have often faced criticism for underreporting cases and lacking a control group to assess the increase in baseline risk. METHODS: The temporal association between myocarditis onset and COVID-19 vaccination was studied. To overcome limitations, a novel modified self-controlled case series method was employed, explicitly modeling the case reporting process in VAERS data. RESULTS: We found an increased risk of myocarditis during the 1- to 3-day period following the second and third doses of both the BNT162b2 vaccine and the mRNA-1273 vaccine. Following the second dose, the relative incidence (RI) was 4.89 (95% confidence interval (CI), 2.39-10.08) for the BNT162b2 vaccine and 2.86 (95% CI: 1.18-7.03) for the mRNA-1273 vaccine. Similarly, following the third dose, the RI was 9.04 (95% CI: 2.79-40.99) for the BNT162b2 vaccine and 4.71 (95% CI: 1.42-19.09) for the mRNA-1273 vaccine. No significant increase in risk was observed during other periods. Notably, our analysis also identified a similar increased risk of myocarditis among individuals aged below 30. CONCLUSIONS: These findings raise safety concerns regarding COVID-19 mRNA vaccines, provide insights into the quantification of myocarditis risk at different postvaccination periods, and offer a novel approach to interpreting passive surveillance system data.

Germline HAVCR2/TIM-3 Checkpoint Inhibitor Receptor Deficiency in Recurrent Autoinflammatory Myocarditis.

Myocarditis can be caused by viral infection, drug reaction or general inflammatory condition. To provide understanding on inflammatory myocarditis, we describe clinical, genetic, and immunological properties of a young male patient who suffered from recurrent myocarditis episodes since the age of four years. Electrocardiography, troponin I/T, echocardiography, myocardial magnetic resonance imaging and histological findings were consistent with recurrent myocarditis episodes. Homozygous c.245 A > G p.Tyr82Cys pathogenic variant in Hepatitis A Virus Cellular Receptor 2 (HAVCR2) gene encoding T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) receptor was found. Peripheral blood mononuclear cells were collected when the patient was asymptomatic; CD4+ and CD8+ T lymphoblasts, CD56+ natural killer cells and CD14+ monocytes were negative for surface TIM-3 expression. In vitro, TLR4 mediated interleukin-1ß (IL-1ß) response was high after LPS/ATP stimulation. Clinical symptoms responded to IL-1 receptor antagonist anakinra. TIM-3 p.Tyr82Cys CD4+ and CD8+ T cell proliferation in vitro was unrestrained. Findings on IL-2, interferon gamma, regulatory T cells, signal transducer and activator of transcription (STAT) 1, 3 and 4 phosphorylation, and PD-1 and LAG-3 checkpoint inhibitor receptor analyses were comparable to controls. We conclude that TIM-3 deficiency due to homozygous HAVCR2 c.245 A > G p.Tyr82Cys pathogenic variant in the patient described here is associated with autoinflammatory symptoms limited to early onset recurrent febrile myocarditis. Excessive IL-1ß production and defective regulation of T cell proliferation may contribute to this clinical condition responsive to anakinra treatment.

Cardiomyopathies in children and adolescents: aetiology, management, and outcomes in the European Society of Cardiology EURObservational Research Programme Cardiomyopathy and Myocarditis Registry.

BACKGROUND AND AIMS: Childhood-onset cardiomyopathies are rare and poorly characterized. This study examined the baseline characteristics and 1-year follow-up of children with cardiomyopathy in the first European Cardiomyopathy Registry. METHODS: Prospective data were collected on individuals aged 1-<18 years enrolled in the European Society of Cardiology EURObservational Research Programme Cardiomyopathy and Myocarditis long-term registry (June 2014-December 2016). RESULTS: A total of 633 individuals aged ≤18 years with hypertrophic [HCM; n = 388 (61.3%)], dilated [DCM; n = 206 (32.5%)], restrictive [RCM; n = 28 (4.4%)], and arrhythmogenic right ventricular cardiomyopathy [ARVC; n = 11 (1.7%)] were enrolled by 23 referral centres in 14 countries. Median age at diagnosis was 4.0 [interquartile range (IQR) 0-10] years, and there was a male predominance [n = 372 (58.8%)] across all subtypes, with the exception of DCM diagnosed <10 years of age; 621 (98.1%) patients were receiving cardiac medication and 80 (12.6%) had an implantable cardioverter-defibrillator. A total of 253 patients (253/535, 47.3%) had familial disease. Genetic testing was performed in 414 (67.8%) patients with a pathogenic or likely pathogenic variant reported in 250 (60.4%). Rare disease phenocopies were reported in 177 patients (28.0%) and were most frequent in patients under 10 years [142 (30.9%) vs. 35 (19.6%); P = .003]. Over a median follow-up of 12.5 months (IQR 11.3-15.3 months), 18 patients (3.3%) died [HCM n = 9 (2.6%), DCM n = 5 (3.0%), RCM n = 4 (16.0%)]. Heart failure events were most frequent in RCM patients (36.0%). CONCLUSIONS: The findings confirm the heterogeneous aetiology of childhood cardiomyopathies and show a high frequency of familial disease. Outcomes differed by cardiomyopathy subtype, highlighting a need for disease-specific evaluation and treatment.

Coxsackie B virus-induced myocarditis in a patient with a history of lymphoma: A case report and review of literature.

INTRODUCTION: In rare occasions, coxsackievirus infections can cause serious illness, such as encephalitis and myocarditis. The immunotherapies of cancer could increase the risk of myocarditis, especially when applying immune checkpoint inhibitors. Herein, we report a rare case of Coxsackie B virus-induced myocarditis in a patient with a history of lymphoma. CASE PRESENTATION: A 32-year-old woman was admitted to the hospital with recurrent fever for more than 20 days, and she had a history of lymphoma. Before admission, the positron emission tomography/computed tomography result indicated that the patient had no tumor progression, and she was not considered the cancer-related fever upon arriving at our hospital. Patient's red blood cell, platelet count, and blood pressure were decreased. In addition, she had sinus bradycardia and 3 branch blocks, which was consistent with acute high lateral and anterior wall myocardial infarction. During hospitalization, the patient had recurrent arrhythmia, repeated sweating, poor mentation, dyspnea, and Coxsackie B virus were detected in patient's blood samples by pathogen-targeted next-generation sequencing. The creatine kinase, creatine kinase MB, and N-terminal pro-brain natriuretic peptide were persistently elevated. Consequently, the patient was diagnosed with viral myocarditis induced by Coxsackie B virus, and treated with acyclovir, gamma globulin combined with methylprednisolone shock therapy, trimetazidine, levosimendan, sildenan, continuous pump pressors with m-hydroxylamine, entecavir, adefovir, glutathione, pantoprazole, and low-molecular-weight heparin. Her symptoms worsened and died. CONCLUSION: We reported a case with a history of lymphoma presented with fever, myocardial injury, who was ultimately diagnosed with Coxsackie B virus-induced myocarditis. Moreover, pathogen-targeted next-generation sequencing indeed exhibited higher sensitivity compared to mNGS in detecting Coxsackie B virus.

A multidisciplinary approach of a patient with pheochromocytoma presenting as recurrent acute fulminant myocarditis: A rare case report and comprehensive review of literature.

Fulminant myocarditis (FM) is a rare illness characterized by abrupt and severe widespread cardiac inflammation, which frequently results in mortality due to cardiogenic shock, ventricular arrhythmias, or multiorgan system failure. Pheochromocytoma is an uncommon and difficult-to-diagnose cause of FM, and it is associated with a significant risk of recurrent acute myocarditis. There is, however, little information on reoccurring acute FM. Herein, we report a rare case of recurrent acute FM due to pheochromocytoma. We present the case of a 22-year-old woman who was admitted to our hospital three days previously with acute dyspnea. Five months prior, the patient was diagnosed with post-acute myocarditis, and a massive tumor on the right adrenal gland was discovered, which lead to pheochromocytoma diagnosis. In this present admission, following the exclusion of infection, autoimmune, and metabolic derangements, pheochromocytoma was presumed to be the reason for the recurrence and more severe acute FM during the current hospitalization. The patient responded favorably to high-dose steroids combined with heart failure therapy regimens. To detect recurrent acute myocarditis related to pheochromocytoma, a multidisciplinary approach was used, including several laboratory biomarkers and imaging findings. Following pheochromocytoma removal and biopsy, the patient recovered satisfactorily. Our findings may provide beneficial contributions to the literature as pheochromocytoma is an uncommon but important cause of recurrent acute myocarditis. A multidisciplinary approach is essential in identifying acute FM and determining the underlying causes of this malady.

Understanding long COVID myocarditis: A comprehensive review.

Infectious diseases are a cause of major concern in this twenty-first century. There have been reports of various outbreaks like severe acute respiratory syndrome (SARS) in 2003, swine flu in 2009, Zika virus disease in 2015, and Middle East Respiratory Syndrome (MERS) in 2012, since the start of this millennium. In addition to these outbreaks, the latest infectious disease to result in an outbreak is the SARS-CoV-2 infection. A viral infection recognized as a respiratory illness at the time of emergence, SARS-CoV-2 has wreaked havoc worldwide because of its long-lasting implications like heart failure, sepsis, organ failure, etc., and its significant impact on the global economy. Besides the acute illness, it also leads to symptoms months later which is called long COVID or post-COVID-19 condition. Due to its ever-increasing prevalence, it has been a significant challenge to treat the affected individuals and manage the complications as well. Myocarditis, a long-term complication of coronavirus disease 2019 (COVID-19) is an inflammatory condition involving the myocardium of the heart, which could even be fatal in the long term in cases of progression to ventricular dysfunction and heart failure. Thus, it is imperative to diagnose early and treat this condition in the affected individuals. At present, there are numerous studies which are in progress, investigating patients with COVID-19-related myocarditis and the treatment strategies. This review focuses primarily on myocarditis, a life-threatening complication of COVID-19 illness, and endeavors to elucidate the pathogenesis, biomarkers, and management of long COVID myocarditis along with pipeline drugs in detail.