Viral myocarditis: from experimental models to molecular diagnosis in patients

Endomyocardial biopsy: safety and prognostic utility in paediatric and adult myocarditis in the European Society of Cardiology EURObservational Research Programme Cardiomyopathy and Myocarditis Long-Term Registry

BACKGROUND AND AIMS

Contemporary multicentre data on clinical and diagnostic spectrum and outcome in myocarditis are limited. Study aims were to describe baseline features, 1-year follow-up, and baseline predictors of outcome in clinically suspected or biopsy-proven myocarditis (2013 European Society of Cardiology criteria) in adult and paediatric patients from the EURObservational Research Programme Cardiomyopathy and Myocarditis Long-Term Registry.

METHODS

Five hundred eighty-one (68.0% male) patients, 493 adults, median age 38 (27-52) years, and 88 children, aged 8 (3-13) years, were divided into 3 groups: Group 1 (n = 233), clinically suspected myocarditis with abnormal cardiac magnetic resonance; Group 2 (n = 222), biopsy-proven myocarditis; and Group 3 (n = 126) clinically suspected myocarditis with normal or inconclusive or no cardiac magnetic resonance. Baseline features were analysed overall, in adults vs. children, and among groups. One-year outcome events included death/heart transplantation, ventricular assist device (VAD) or implantable cardioverter defibrillator (ICD) implantation, and hospitalization for cardiac causes.

RESULTS

Endomyocardial biopsy, mainly right ventricular, had a similarly low complication rate in children and adults (4.7% vs. 4.9%, P = NS), with no procedure-related death. A classical myocarditis pattern on cardiac magnetic resonance was found in 31.3% of children and in 57.9% of adults with biopsy-proven myocarditis (P < .001). At 1-year follow-up, 11/410 patients (2.7%) died, 7 (1.7%) received a heart transplant, 3 underwent VAD (0.7%), and 16 (3.9%) underwent ICD implantation. Independent predictors at diagnosis of death or heart transplantation or hospitalization or VAD implantation or ICD implantation at 1-year follow-up were lower left ventricular ejection fraction and the need for immunosuppressants for new myocarditis diagnosis refractory to non-aetiology-driven therapy.

CONCLUSIONS

Endomyocardial biopsy was safe, and cardiac magnetic resonance using Lake Louise criteria was less sensitive, particularly in children. Virus-negative lymphocytic myocarditis was predominant both in children and adults, and use of immunosuppressive treatments was low. Lower left ventricular ejection fraction and the need for immunosuppressants at diagnosis were independent predictors of unfavourable outcome events at 1 year.

Three Modes of Viral Adaption by the Heart

Viruses elicit long-term adaptive responses in the tissues they infect. Understanding viral adaptions in humans is difficult in organs such as the heart, where primary infected material is not routinely collected. In search of asymptomatic infections with accompanying host adaptions, we mined for cardio-pathogenic viruses in the unaligned reads of nearly one thousand human hearts profiled by RNA sequencing. Among virus-positive cases (~20%), we identified three robust adaptions in the host transcriptome related to inflammatory NFκB signaling and post-transcriptional regulation by the p38-MK2 pathway. The adaptions are not determined by the infecting virus, and they recur in infections of human or animal hearts and cultured cardiomyocytes. Adaptions switch states when NFκB or p38-MK2 are perturbed in cells engineered for chronic infection by the cardio-pathogenic virus, coxsackievirus B3. Stratifying viral responses into reversible adaptions adds a targetable systems-level simplification for infections of the heart and perhaps other organs.

Acetylation of FOXO1 activates Bim expression involved in CVB3 induced cardiomyocyte apoptosis

Viral myocarditis (VMC) is the major reason for sudden cardiac death among both children and young adults. Of these, coxsackievirus B3 (CVB3) is the most common causative agent of myocarditis. Recently, the role of signaling pathways in the pathogenesis of VMC has been evaluated in several studies, which has provided a new perspective on identifying potential therapeutic targets for this hitherto incurable disease. In the present study, in vivo and in vitro experiments showed that CVB3 infection leads to increased Bim expression and triggers apoptosis. In addition, by knocking down Bim using RNAi, we further confirmed the biological function of Bim in apoptosis induced by CVB3 infection. We additionally found that Bim and forkhead box O1 class (FOXO1) inhibition significantly increased the viability of CVB3-infected cells while blocking viral replication and viral release. Moreover, CVB3-induced Bim expression was directly dependent on FOXO1 acetylation, which is catalyzed by the co-regulation of CBP and SirTs. Furthermore, the acetylation of FOXO1 was an important step in Bim activation and apoptosis induced by CVB3 infection. The findings of this study suggest that CVB3 infection induces apoptosis through the FOXO1 acetylation-Bim pathway, thus providing new insights for developing potential therapeutic targets for enteroviral myocarditis.

Cardiac Involvement Due to COVID-19: Insights from Imaging and Histopathology

Lingering cardiac symptoms are increasingly recognised complications of severe acute respiratory syndrome coronavirus 2 infection, now referred to as post-acute cardiovascular sequelae of COVID-19 (PASC). In the acute phase, cardiac injury is driven by cytokine release and stems from ischaemic and thrombotic complications, resulting in myocardial necrosis. Patients with pre-existing cardiac conditions are particularly vulnerable. Myocarditis due to a direct viral infection is rare. Chronic symptoms relate to either worsening of pre-existing heart disease (PASC - cardiovascular disease) or delayed chronic inflammatory condition due to heterogenous immune dysregulation (PASC - cardiovascular syndrome), the latter affecting a broad segment of previously well people. Both PASC presentations are associated with increased cardiovascular risk, long-term disability and reduced quality of life. The recognition and management of PASC in clinical settings remains a considerable challenge. Sensitive diagnostic methods are needed to detect subtler inflammatory changes that underlie the persistent symptoms in PASC - cardiovascular syndrome, alongside considerable clinical experience in inflammatory cardiac conditions.

Dilated cardiomyopathy: causes, mechanisms, and current and future treatment approaches

Dilated cardiomyopathy is conventionally defined as the presence of left ventricular or biventricular dilatation or systolic dysfunction in the absence of abnormal loading conditions (eg, primary valve disease) or significant coronary artery disease sufficient to cause ventricular remodelling. This definition has been recognised as overly restrictive, as left ventricular hypokinesis without dilation could be the initial presentation of dilated cardiomyopathy. The causes of dilated cardiomyopathy comprise genetic (primary dilated cardiomyopathy) or acquired factors (secondary dilated cardiomyopathy). Acquired factors include infections, toxins, cancer treatment, endocrinopathies, pregnancy, tachyarrhythmias, and immune-mediated diseases. 5-15% of patients with acquired dilated cardiomyopathy harbour a likely pathogenic or pathogenic gene variant (ie, gene mutation). Therefore, the diagnostic tests and therapeutic approach should always consider both genetic and acquired factors. This Seminar will focus on the current multidimensional diagnostic and therapeutic approach and discuss the underlying pathophysiology that could drive future treatments aiming to repair or replace the existing gene mutation, or target the specific inflammatory, metabolic, or pro-fibrotic drivers of genetic or acquired dilated cardiomyopathy.

COVID-19 Associated Myocarditis: Prevalence, Pathophysiology, Diagnosis, and Management

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a pandemic and affected public health greatly. While COVID-19 primarily damages the lungs, leading to cough, sore throat, pneumonia, or acute respiratory distress syndrome, it also infects other organs and tissues, including the cardiovascular system. In particular, myocarditis is a well-recognized severe complication of COVID-19 infection and could result in adverse outcomes. Angiotensin-Converting Enzyme2 is thought to play a pivotal role in SARS-CoV-2 infection, and immune overresponse causes overwhelming damage to the host's myocardium. Direct viral infection and injury do take a part as well, but more evidence is needed to strengthen this proposal. The clinical abnormalities include elevated cardiac biomarkers and electrocardiogram changes and impaired cardiac function that might be presented in echocardiography and cardiovascular magnetic resonance imaging. If necessary, the endomyocardial biopsy would give more forceful information to diagnosis and aid in treatment. Comparisons between COVID-19 myocarditis and other viral myocarditis are also discussed briefly.

Acute Respiratory Distress Syndrome in Patients with Cardiovascular Disease

Heart and lung interaction within the thoracic cavity is well known during inhalation and exhalation, both spontaneously and during mechanical ventilation. Disease and dysfunction of one organ affect the function of the other. A review of the cause-and-effect relationship between cardiovascular disease and acute respiratory distress syndrome (ARDS) is of significance, as the disease burden of both conditions has both a national and global impact on health care. This literature review examines the relationship between cardiovascular disease and ARDS over the past 25 years.

Myocarditis: Etiology, Pathogenesis, and Their Implications in Clinical Practice

Myocarditis is an inflammatory disease of the myocardium caused by infectious or non-infectious agents. It can lead to serious short-term and long-term sequalae, such as sudden cardiac death or dilated cardiomyopathy. Due to its heterogenous clinical presentation and disease course, challenging diagnosis and limited evidence for prognostic stratification, myocarditis poses a great challenge to clinicians. As it stands, the pathogenesis and etiology of myocarditis is only partially understood. Moreover, the impact of certain clinical features on risk assessment, patient outcomes and treatment options is not entirely clear. Such data, however, are essential in order to personalize patient care and implement novel therapeutic strategies. In this review, we discuss the possible etiologies of myocarditis, outline the key processes governing its pathogenesis and summarize best available evidence regarding patient outcomes and state-of-the-art therapeutic approaches.

Leitlinie Myokarditis der Deutschen Gesellschaft für Pädiatrische Kardiologie

This consensus statement presents updated recommendations on diagnosis and treatment of myocarditis in childhood.

Myocarditis: causes, mechanisms, and evolving therapies

INTRODUCTION

Myocarditis is a severe lymphocyte-mediated inflammatory disorder of the heart, mostly caused by viruses and immune checkpoint inhibitors (ICIs). Recently, myocarditis as a rare adverse event of mRNA vaccines for SARS-CoV-2 has caused global attention. The clinical consequences of myocarditis can be very severe, but specific treatment options are lacking or not yet clinically proven.

AREAS COVERED

This paper offers a brief overview of the biology of viruses that frequently cause myocarditis, focusing on mechanisms important for viral entry and replication following host infection. Current and new potential therapeutic targets/strategies especially for viral myocarditis are reviewed systematically. In particular, the immune system in myocarditis is dissected with respect to infective viral and non-infective, ICI-induced myocarditis.

EXPERT OPINION

Vaccination is an excellent emerging preventative strategy for viral myocarditis, but most vaccines still require further development. Anti-viral treatments that inhibit viral replication need to be considered following viral infection in host myocardium, as lower viral load reduces inflammation severity. Understanding how the immune system continues to damage the heart even after viral clearance will define novel therapeutic targets/strategies. We propose that viral myocarditis can be best treated using a combination of antiviral agents and immunotherapies that control cytotoxic T cell activity.

Comparison of COVID-19 Vaccine-Associated Myocarditis and Viral Myocarditis Pathology

The COVID-19 pandemic has led to significant loss of life and severe disability, justifying the expedited testing and approval of messenger RNA (mRNA) vaccines. While found to be safe and effective, there have been increasing reports of myocarditis after COVID-19 mRNA vaccine administration. The acute events have been severe enough to require admission to the intensive care unit in some, but most patients fully recover with only rare deaths reported. The pathways involved in the development of vaccine-associated myocarditis are highly dependent on the specific vaccine. COVID-19 vaccine-associated myocarditis is believed to be primarily caused by uncontrolled cytokine-mediated inflammation with possible genetic components in the interleukin-6 signaling pathway. There is also a potential autoimmune component via molecular mimicry. Many of these pathways are similar to those seen in viral myocarditis, indicating a common pathophysiology. There is concern for residual cardiac fibrosis and increased risk for the development of cardiomyopathies later in life. This is of particular interest for patients with congenital heart defects who are already at increased risk for fibrotic cardiomyopathies. Though the risk for vaccine-associated myocarditis is important to consider, the risk of viral myocarditis and other injury is far greater with COVID-19 infection. Considering these relative risks, it is still recommended that the general public receive vaccination against COVID-19, and it is particularly important for congenital heart defect patients to receive vaccination for COVID-19.

Analysis of long noncoding RNAs and messenger RNAs expression profiles in the hearts of mice with acute viral myocarditis

Acute viral myocarditis (AVMC) is a common acute myocardial inflammation caused by viral infections, which can lead to severe cardiac dysfunction. Several long noncoding RNAs (lncRNAs) with aberrant expression have been identified in the pathogenesis of AVMC. However, the expression profiles and functions of lncRNAs in AVMC have not been fully elucidated. In the present study, we constructed AVMC mouse models by intraperitoneal injection of coxsackievirus B3 (CVB3) and performed RNA sequencing (RNA-seq) on heart tissues to investigate the differences in lncRNAs and messenger RNAs (mRNAs) expression profiles. Based on the cutoff criteria of adjusted p-values (padj) <0.05 and |log2FoldChange| >1, a total of 1122 differentially expressed lncRNAs (DElncRNAs) and 3186 differentially expressed mRNAs (DEmRNAs) were screened, including 734 upregulated and 388 downregulated lncRNAs, 1821 upregulated and 1365 downregulated mRNAs. RT-qPCR analysis validated that the expression patterns of 12 randomly selected genes (6 DElncRNAs and 6 DEmRNAs) were highly consistent with those in RNA-seq, proving the reliability of the RNA-seq data. Then, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses revealed that differentially expressed genes were mainly involved in metabolic and immune-related processes. Furthermore, co-expression networks between DElncRNAs and DEmRNAs in cytokine-cytokine receptor interaction, MAPK signaling pathway, and PI3K-Akt signaling pathway were constructed to study the molecular interactions of these molecules. Our study, for the first time, reveals the expression profiles of lncRNAs and mRNAs associated with AVMC, which may shed light on the roles of lncRNAs in disease pathogenesis and aid in discovering new therapeutic targets.

Persistent viral infections and their role in heart disease

Viral infections are the culprit of many diseases, including inflammation of the heart muscle, known as myocarditis. Acute myocarditis cases have been described in scientific literature, and viruses, such as parvovirus B19, coxsackievirus B3, or more recently, SARS-CoV-2, were the direct cause of cardiac inflammation. If not treated, myocarditis could progress to dilated cardiomyopathy, which permanently impairs the heart and limits a person's lifespan. Accumulated evidence suggests that certain viruses may persist in cardiac tissue after the initial infection, which could open up the door to reactivation under favorable conditions. Whether this chronic infection contributes to, or initiates, cardiac damage over time, remains a pressing issue in the field of virus-induced heart pathology, and it is directly tied to patients' treatment. Previously, large case studies found that a few viruses: parvovirus B19, coxsackievirus, adenovirus, human herpesvirus 6, cytomegalovirus and Epstein-Barr virus, are most commonly found in human endomyocardial biopsy samples derived from patients experiencing cardiac inflammation, or dilated cardiomyopathy. SARS-CoV-2 infection has also been shown to have cardiovascular consequences. This review examines the role of viral persistence in cardiac inflammation and heart disease, and discusses its implications for patients' outcomes.

Myocarditis following COVID-19 vaccine: incidence, presentation, diagnosis, pathophysiology, therapy, and outcomes put into perspective. A clinical consensus document supported by the Heart Failure Association of the European Society of Cardiology (ESC) and the ESC Working Group on Myocardial and Pericardial Diseases

Over 10 million doses of COVID-19 vaccines based on RNA technology, viral vectors, recombinant protein, and inactivated virus have been administered worldwide. Although generally very safe, post-vaccine myocarditis can result from adaptive humoral and cellular, cardiac-specific inflammation within days and weeks of vaccination. Rates of vaccine-associated myocarditis vary by age and sex with the highest rates in males between 12 and 39 years. The clinical course is generally mild with rare cases of left ventricular dysfunction, heart failure and arrhythmias. Mild cases are likely underdiagnosed as cardiac magnetic resonance imaging (CMR) is not commonly performed even in suspected cases and not at all in asymptomatic and mildly symptomatic patients. Hospitalization of symptomatic patients with electrocardiographic changes and increased plasma troponin levels is considered necessary in the acute phase to monitor for arrhythmias and potential decline in left ventricular function. In addition to evaluation for symptoms, electrocardiographic changes and elevated troponin levels, CMR is the best non-invasive diagnostic tool with endomyocardial biopsy being restricted to severe cases with heart failure and/or arrhythmias. The management beyond guideline-directed treatment of heart failure and arrhythmias includes non-specific measures to control pain. Anti-inflammatory drugs such as non-steroidal anti-inflammatory drugs, and corticosteroids have been used in more severe cases, with only anecdotal evidence for their effectiveness. In all age groups studied, the overall risks of SARS-CoV-2 infection-related hospitalization and death are hugely greater than the risks from post-vaccine myocarditis. This consensus statement serves as a practical resource for physicians in their clinical practice, to understand, diagnose, and manage affected patients. Furthermore, it is intended to stimulate research in this area.

Quantitative analysis of respiratory viral distribution in forensic autopsy cases

Respiratory viruses can cause fatal systemic infections; therefore, post-mortem diagnosis is essential in forensic autopsy cases. However, little is known regarding the distribution of respiratory viruses in the body. In this study, we investigated the anatomical distribution of respiratory viruses in 48 forensic autopsy cases suspected of viral infections at our institute. Fast Track Diagnostics (FTD) Respiratory Pathogens 21 was used as a screening test for 20 respiratory viruses in nasopharyngeal swabs. In cases with positive results for virus detection by the screening test, the detected viruses were quantified in body fluid and organ specimens by virus-specific real-time reverse transcription polymerase chain reaction (RT-PCR) and digital PCR. Viruses were detected in 33 cases, with the viral distribution and load differing among the cases. Since various respiratory viruses were detected from the nasopharyngeal swab and its viral load was higher than those of other body fluid specimens, the nasopharyngeal swab was suggested as a useful specimen for the post-mortem detection of respiratory viruses. Viruses were detected in almost all specimens including the serum in six cases. Considering the viral distribution in the body, pathological findings, and ante-mortem symptoms, these cases were presumed to be systemically infected, having died in the acute infection phase. In conclusion, the anatomical distribution of respiratory viruses can help indicate ante-mortem systemic conditions and the cause of death.

Nonrespiratory sites of influenza-associated disease: mechanisms and experimental systems for continued study

The productive replication of human influenza viruses is almost exclusively restricted to cells in the respiratory tract. However, a key aspect of the host response to viral infection is the production of inflammatory cytokines and chemokines that are not similarly tissue restricted. As such, circulating inflammatory mediators, as well as the resulting activated immune cells, can induce damage throughout the body, particularly in individuals with underlying conditions. As a result, more holistic experimental approaches are required to fully understand the pathogenesis and scope of influenza virus-induced disease. This review summarizes what is known about some of the most well-appreciated nonrespiratory tract sites of influenza virus-induced disease, including neurological, cardiovascular, gastrointestinal, muscular and fetal developmental phenotypes. In the context of this discussion, we describe the in vivo experimental systems currently being used to study nonrespiratory symptoms. Finally, we highlight important future questions and potential models that can be used for a more complete understanding of influenza virus-induced disease.

The Spontaneous Course of Human Herpesvirus 6 DNA-Associated Myocarditis and the Effect of Immunosuppressive Intervention

Introduction: This study investigated the spontaneous clinical course of patients with endomyocardial biopsy (EMB)-proven lymphocytic myocarditis and cardiac human herpesvirus 6 (HHV6) DNA presence, and the effectiveness of steroid-based intervention in HHV6-positive patients. Results: 756 heart failure (HF) patients underwent an EMB procedure to determine the underlying cause of unexplained HF. Low levels of HHV6 DNA, detectable by nested PCR only, were found in 10.4% of the cases (n = 79) of which 62% (n = 49) showed myocardial inflammation. The spontaneous course of patients with EMB-proven HHV6 DNA-associated lymphocytic myocarditis (n = 26) showed significant improvements in the left ventricular ejection fraction (LVEF) and clinical symptoms, respectively, in 15/26 (60%) patients, 3–12 months after disease onset. EMB mRNA expression of components of the NLRP3 inflammasome pathway and protein analysis of cardiac remodeling markers, analyzed by real-time PCR and MALDI mass spectrometry, respectively, did not differ between HHV6-positive and -negative patients. In another cohort of patients with ongoing symptoms related to lymphocytic myocarditis associated with cardiac levels of HHV6-DNA copy numbers <500 copies/µg cardiac DNA, quantified by real-time PCR, the efficacy and safety of steroid-based immunosuppression for six months was investigated. Steroid-based immunosuppression improved the LVEF (≥5%) in 8/10 patients and reduced cardiac inflammation in 7/10 patients, without an increase in cardiac HHV6 DNA levels in follow-up EMBs. Conclusion: Low HHV6 DNA levels are frequently detected in the myocardium, independent of inflammation. In patients with lymphocytic myocarditis with low levels of HHV6 DNA, the spontaneous clinical improvement is nearby 60%. In selected symptomatic patients with cardiac HHV6 DNA copy numbers less than 500 copies/µg cardiac DNA and without signs of an active systemic HHV6 infection, steroid-based therapy was found to be effective and safe. This finding needs to be further confirmed in large, randomized trials.

Knockdown of LncRNA MALAT1 Alleviates Coxsackievirus B3-Induced Acute Viral Myocarditis in Mice via Inhibiting Th17 Cells Differentiation

Acute viral myocarditis (AVMC), most often caused by coxsackievirus B3 (CVB3) infection, is characterized by myocardial inflammation associated with high morbidity and mortality. A pathogenic role for T helper (Th) 17 cells in AVMC is well established. Long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been shown to play a key role in various inflammatory diseases. However, the expression of MALAT1 and its impact on Th17 cells differentiation in AVMC remain unclear. In the present study, we found that MALAT1 was highly expressed in mice with AVMC, and the expression was correlated positively with cardiac pathological scores, cardiac IL-17 mRNA expression, and the percentages of splenic Th17 cells. We further demonstrated that MALAT1 knockdown could significantly alleviate the severity of disease and inhibit the differentiation of Th17 cells, accompanying the reduced mRNA expression of RORγt and productions of Th17-related pro-inflammatory cytokines in vivo. Additionally, in vitro analysis showed that MALAT1 knockdown suppressed naïve CD4⁺ T cells differentiation towards Th17 cells. In conclusion, our results suggest that MALAT1 knockdown alleviates CVB3-induced AVMC in mice, which may be partially attributable to the decline in Th17 cells responses. MALAT1 may serve as a novel therapeutic option in AVMC.

Fatal human herpes virus 6B myocarditis: Postmortem diagnosis of HHV-6B based on CD134+ T-cell tropism

Human herpes virus 6 (HHV-6) is one of the most important pathogens of viral myocarditis, and is often responsible for sudden death in young adults. A 59-year-old immunocompetent man died of serious lymphocytic myocarditis, and his peripheral blood sample showed HHV-6 DNAemia. Recently, HHV-6 cell entry and reactivation have been suggested to be regulated by the expression of specific CD receptors on T lymphocytes. Here, we report a case of HHV-6 myocarditis diagnosed using an experimental method focused on this unique cell tropism. The interaction between HHV-6 and CD expression was assessed using an immunofluorescence assay. Colocalization between HHV-6B and CD134 was detected in lymphocytes infiltrating the myocardium, which was highly suggestive of an active HHV-6B infection and could be a useful criterion for postmortem diagnosis of HHV-6B myocarditis in the acute phase.

Advanced detection strategies for cardiotropic virus infection in a cohort study of heart failure patients

The prevalence and contribution of cardiotropic viruses to various expressions of heart failure are increasing, yet primarily underappreciated and underreported due to variable clinical syndromes, a lack of consensus diagnostic standards and insufficient clinical laboratory tools. In this study, we developed an advanced methodology for identifying viruses across a spectrum of heart failure patients. We designed a custom tissue microarray from 78 patients with conditions commonly associated with virus-related heart failure, conditions where viral contribution is typically uncertain, or conditions for which the etiological agent remains suspect but elusive. Subsequently, we employed advanced, highly sensitive in situ hybridization to probe for common cardiotropic viruses: adenovirus 2, coxsackievirus B3, cytomegalovirus, Epstein-Barr virus, hepatitis C and E, influenza B and parvovirus B19. Viral RNA was detected in 46.4% (32/69) of heart failure patients, with 50% of virus-positive samples containing more than one virus. Adenovirus 2 was the most prevalent, detected in 27.5% (19/69) of heart failure patients, while in contrast to previous reports, parvovirus B19 was detected in only 4.3% (3/69). As anticipated, viruses were detected in 77.8% (7/9) of patients with viral myocarditis and 37.5% (6/16) with dilated cardiomyopathy. Additionally, viruses were detected in 50% of patients with coronary artery disease (3/6) and hypertrophic cardiomyopathy (2/4) and in 28.6% (2/7) of transplant rejection cases. We also report for the first time viral detection within a granulomatous lesion of cardiac sarcoidosis and in giant cell myocarditis, conditions for which etiological agents remain unknown. Our study has revealed a higher than anticipated prevalence of cardiotropic viruses within cardiac muscle tissue in a spectrum of heart failure conditions, including those not previously associated with a viral trigger or exacerbating role. Our work forges a path towards a deeper understanding of viruses in heart failure pathogenesis and opens possibilities for personalized patient therapeutic approaches.

Transcriptional Active Parvovirus B19 Infection Predicts Adverse Long-Term Outcome in Patients with Non-Ischemic Cardiomyopathy

Parvovirus B19 (B19V) is the predominant cardiotropic virus currently found in endomyocardial biopsies (EMBs). However, direct evidence showing a causal relationship between B19V and progression of inflammatory cardiomyopathy are still missing. The aim of this study was to analyze the impact of transcriptionally active cardiotropic B19V infection determined by viral RNA expression upon long-term outcomes in a large cohort of adult patients with non-ischemic cardiomyopathy in a retrospective analysis from a prospective observational cohort. In total, the analyzed study group comprised 871 consecutive B19V-positive patients (mean age 50.0 ± 15.0 years) with non-ischemic cardiomyopathy who underwent EMB. B19V-positivity was ascertained by routine diagnosis of viral genomes in EMBs. Molecular analysis of EMB revealed positive B19V transcriptional activity in n = 165 patients (18.9%). Primary endpoint was all-cause mortality in the overall cohort. The patients were followed up to 60 months. On the Cox regression analysis, B19V transcriptional activity was predictive of a worse prognosis compared to those without actively replicating B19V (p = 0.01). Moreover, multivariable analysis revealed transcriptional active B19V combined with inflammation [hazard ratio 4.013, 95% confidence interval 1.515–10.629 (p = 0.005)] as the strongest predictor of impaired survival even after adjustment for age and baseline LVEF (p = 0.005) and independently of viral load. The study demonstrates for the first time the pathogenic clinical importance of B19V with transcriptional activity in a large cohort of patients. Transcriptionally active B19V infection is an unfavourable prognostic trigger of adverse outcome. Our findings are of high clinical relevance, indicating that advanced diagnostic differentiation of B19V positive patients is of high prognostic importance.

Toll-Like Receptors: Are They Taking a Toll on the Heart in Viral Myocarditis?

Myocarditis is an inflammatory disease of the heart with viral infections being the most common aetiology. Its complex biology remains poorly understood and its clinical management is one of the most challenging in the field of cardiology. Toll-like receptors (TLRs), a family of evolutionarily conserved pattern recognition receptors, are increasingly known to be implicated in the pathophysiology of viral myocarditis. Their central role in innate and adaptive immune responses, and in the inflammatory reaction that ensues, indeed makes them prime candidates to profoundly affect every stage of the disease process. This review describes the pathogenesis and pathophysiology of viral myocarditis, and scrutinises the role of TLRs in every phase. We conclude with directions for future research in this field.

Association of persistent tachycardia with early myocardial dysfunction in children undergoing allogeneic hematopoietic cell transplantation

Cancer survivors who have undergone hematopoietic cell transplantation (HCT) are at risk for myocardial dysfunction. Children who receive allogenic HCT encounter systemic inflammation resulting in tachycardia and hypertension. The effect of these abnormalities on myocardial function is not known. The aim of this study was to determine whether cardiac dysfunction early after HCT can be predicted by tachycardia or hypertension, within a retrospective single-center sample of pediatric HCT recipients. Early tachycardia or hypertension was defined as a majority of values taken from infusion date to 90 days post-infusion being abnormal. Ejection fraction <53% determined systolic dysfunction. A composite score of accepted pediatric diastolic abnormalities determined diastolic dysfunction. Among 80 subjects (median age 8 years), early tachycardia, systolic dysfunction, and diastolic dysfunction were present in 64%, 25%, and 48% of the sample, respectively. In multivariable models, early tachycardia was an independent predictor of early systolic dysfunction (OR = 12.6 [1.4-112.8], p = 0.024) and diastolic dysfunction (OR = 3.9 [1.3-11.5], p = 0.013). Tachycardia and cardiac dysfunction are common and associated with one another in the early period after pediatric HCT. Future studies may elucidate the role of tachycardia and myocardial dysfunction early after HCT as important predictors of future cardiovascular dysfunction.

Myocarditis: Which Role for Genetics?

PURPOSE OF REVIEW

Myocarditis is a polymorphic disease, both in its presentation and clinical course. Recent data suggests that the genetic background, interacting with environmental factors, could be diriment both in the susceptibility and evolution of myocarditis in different clinical presentations. The aim of this paper is to expose the current available evidences and the evolving concepts on this topic, in order to provide insight for improving the clinical management of those patients. In this regard, the main goal is an optimal characterization of each patient's risk, with the purpose of individualizing the treatment and the follow-up.

RECENT FINDINGS

The latest research highlights the possible prognostic role of some pathogenic mutations that could create a vulnerable myocardium prone to myocardial inflammation and also to the development of a long-lasting cardiomyopathy. The identification of these genetic defects and of myocarditis patients requiring genetic testing is emerging as a challenge for the future. In fact, identifying a possible genetic background responsible for a particularly high-risk profile could be of extreme importance in improving management of myocarditis. This and many other aspects in the genetics of myocarditis remain uncovered, and further studies are expected based to refine our daily clinical practice.

Evidence that Ginkgo Biloba could use in the influenza and coronavirus COVID-19 infections

Coronavirus COVID-19 pandemic invades the world. Public health evaluates the incidence of infections and death, which should be reduced and need desperately quarantines for infected individuals. This article review refers to the roles of Ginkgo Biloba to reduce the risk of infection in the respiratory tract, the details on the epidemiology of corona COVID-19 and influenza, and it highlights how the Ginko Biloba could have been used as a novel treatment.Ginkgo Biloba can reduce the risk of infection by several mechanisms; these mechanisms involve Ginkgo Biloba contains quercetin and other constituents, which have anti-inflammatory and immune modulator effects by reducing pro-inflammatory cytokines concentrations. Cytokines cause inflammation which have been induced the injuries in lung lining.Some observational studies confirmed that Ginkgo Biloba reduced the risk of asthma, sepsis and another respiratory disease as well as it reduced the risk of cigarette smoking on respiratory symptoms. While other evidences suggested the characters of Ginkgo Biloba as an antivirus agent through several mechanisms. Ginkgolic acid (GA) can inhibit the fusion and synthesis of viral proteins, thus, it inhibit the Herpes Simplex Virus type1 (HSV-1), genome replication in Human Cytomegalovirus (HCMV) and the infections of the Zika Virus (ZIKV). Also, it inhibits the wide spectrum of fusion by inhibiting the three types of proteins that have been induced fusion as (Influenza A Virus [IAV], Epstein Barr Virus [EBV], HIV and Ebola Virus [EBOV]).The secondary mechanism of GA targeting inhibition of the DNA and protein synthesis in virus, greatly have been related to its strong effects, even afterward the beginning of the infection, therefore, it potentially treats the acute viral contaminations like (Measles and Coronavirus COVID-19). Additionally, it has been used topically as an effective agent on vigorous lesions including (varicella-zoster virus [VZV], HSV-1 and HSV-2). Ginkgo Biloba may be useful for treating the infected people with coronavirus COVID-19 through its beneficial effect. To assess those recommendations should be conducted with random control trials and extensive population studies.

Viral presence-guided immunomodulation in lymphocytic myocarditis: an update

Latest statements from European and American societies recommend to rule out viral presence in endomyocardial biopsy (EMB) via polymerase chain reaction (PCR) analysis before starting immunosuppression or immunomodulation in acute lymphocytic myocarditis presenting with life‐threatening scenarios. However, recommendations in myocarditis are mostly based on heterogeneous studies enrolling patients with inflammatory cardiomyopathies and established heart failure rather than acute myocarditis. Thus, definitive evidence of a survival benefit from immunomodulation guided by viral presence is currently lacking. Finally, distinguishing innocent bystanders from causative agents among EMB‐detected viruses remain challenging and a major goal to achieve in the near future. Therefore, considerable divergence remains between official recommendations and clinical practice, including the possibility of starting immunosuppressive therapy empirically, without knowing viral PCR results. This review systematically discusses the unsolved issues of immunomodulation guided by viral presence in acute lymphocytic myocarditis, namely (i) virus epidemiology and prognosis, (ii) variability of viral presence rates, (iii) the role of potential viral bystander findings, and (iv) the main results of immunosuppression controlled trials in lymphocytic myocarditis. Furthermore, a practical approach for the critical use of viral presence analysis in guiding immunomodulation is provided, highlighting its importance before starting immunosuppression or immunomodulation. Future, multicentre studies are needed to address specific scenarios such as fulminant lymphocytic myocarditis and a virus‐tailored management as for parvovirus B19.

Inflammatory dilated cardiomyopathy : Etiology and clinical management

Inflammatory dilated cardiomyopathy (DCMi) is a syndrome, not an etiological disease entity. The infective etiology and the immunopathology can be best determined through endomyocardial biopsy with a complete work-up by light microscopy, immunohistology, and polymerase chain reaction for microbial agents. This review focuses on the methodological advances in diagnosis in the past few years and exemplifies the importance of an etiology-orientated treatment in different case scenarios. In fulminant nonviral myocarditis, immunosuppressive treatment together with hemodynamic stabilization of the patient via mechanical circulatory support (e.g., microaxial pumps, extracorporeal membrane oxygenation, left ventricular assist device) can be life-saving. For viral inflammatory cardiomyopathy, intravenous immunoglobulin treatment can resolve inflammation and often eradicate the virus.

Adenovirus targets transcriptional and posttranslational mechanisms to limit gap junction function

Adenoviruses are responsible for a spectrum of pathogenesis including viral myocarditis. The gap junction protein connexin43 (Cx43, gene name GJA1) facilitates rapid propagation of action potentials necessary for each heartbeat. Gap junctions also propagate innate and adaptive antiviral immune responses, but how viruses may target these structures is not understood. Given this immunological role of Cx43, we hypothesized that gap junctions would be targeted during adenovirus type 5 (Ad5) infection. We find reduced Cx43 protein levels due to decreased GJA1 mRNA transcripts dependent upon β-catenin transcriptional activity during Ad5 infection, with early viral protein E4orf1 sufficient to induce β-catenin phosphorylation. Loss of gap junction function occurs prior to reduced Cx43 protein levels with Ad5 infection rapidly inducing Cx43 phosphorylation events consistent with altered gap junction conductance. Direct Cx43 interaction with ZO-1 plays a critical role in gap junction regulation. We find loss of Cx43/ZO-1 complexing during Ad5 infection by co-immunoprecipitation and complementary studies in human induced pluripotent stem cell derived-cardiomyocytes reveal Cx43 gap junction remodeling by reduced ZO-1 complexing. These findings reveal specific targeting of gap junction function by Ad5 leading to loss of intercellular communication which would contribute to dangerous pathological states including arrhythmias in infected hearts.

Dendritic cells and regulatory T cells expressing CCR4 provide resistance to coxsackievirus B5-induced pancreatitis

Type B coxsackieviruses (CVB) are enteroviruses responsible for a common infectious myocarditis and pancreatitis. DCs and regulatory T cells (Tregs) are key players in controlling virus replication and regulating the immune response and tissue damage, respectively. However, the mechanisms underlying cellular migration to target tissues remain unclear. In the present study, we found that CVB5 infection induced CCL17 production and controlled the migration of CCR4⁺ DCs and CCR4⁺ Tregs to the pancreatic lymph nodes (pLN). CVB5 infection of CCR4^-/- mice reduced the migration of the CD8α⁺ DC subset and reduced DC activation and production of IFN-β and IL-12. Consequently, CCR4^-/- mice presented decreased IFN-γ-producing CD4⁺ and CD8⁺ T cells, an increased viral load and more severe pancreatitis. In addition, CCR4^-/- mice had impaired Treg accumulation in pLN as well as increased T lymphocyte activation. Adoptive transfer of CCR4⁺ Tregs but not CCR4^- Tregs was able to regulate T lymphocyte activation upon CVB5 infection. The present data reveal a previously unknown role for CCR4 in coordinating immune cell migration to CVB-infected tissues and in controlling subsequent pancreatitis. These new insights may contribute to the design of future therapies for acute and chronic infection of non-polio enteroviruses.

Role of intravenous immunoglobulin therapy in the survival rate of pediatric patients with acute myocarditis: A systematic review and meta-analysis

The treatment of pediatric myocarditis is controversial, and the benefits of intravenous immunoglobulin (IVIG) are inconclusive due to limited data. We searched studies from PubMed, MEDLINE, Embase, and Cochrane Library databases since establishment until October 1st, 2018. Thirteen studies met the inclusion criteria. We included a total of 812 patients with IVIG treatment and 592 patients without IVIG treatment. The meta-analysis showed that the survival rate in the IVIG group was higher than that in the non-IVIG group (odds ratio = 2.133, 95% confidence interval (CI): 1.32-3.43, p = 0.002). There was moderate statistical heterogeneity among the included studies (I² = 35%, p = 0.102). However, after adjustment using Duval and Tweedie's trim and fill method, the point estimate of the overall effect size was 1.40 (95% CI 0.83, 2.35), which became insignificant. Moreover, the meta-regression revealed that age (coefficient = -0.191, 95% CI (-0.398, 0.015), p = 0.069) and gender (coefficient = 0.347, 95% CI (-7.586, 8.279), p = 0.93) were not significantly related to the survival rate. This meta-analysis showed that IVIG treatment was not associated with better survival. The use of IVIG therapy in acute myocarditis in children cannot be routinely recommended based on current evidence. Further prospective and randomized controlled studies are needed to elucidate the effects of IVIG treatment.

Epstein-Barr virus infection as a predisposing factor for multiple sclerosis. An update from molecular biology, immunology and epidemiology

Introduction: Epstein-Barr virus is an infectious agent used to immortalize and induce polyclonal activation of B cells. It has been widely described that this virus produces changes in the cells it infects and in the immune response, and stimulates the development of autoimmune diseases.Objective: To characterize the association between Epstein-Barr virus and multiple sclerosis described in current scientific literature.Materials and methods: A 59-years range literature search was conducted in the PubMed, ScienceDirect, Redalyc and SciELO databases using the following MeSH terms: “Epstein-Barr virus, multiple sclerosis autoimmune diseases, autoimmune diseases of the nervous system”.Results: Many studies describe the association between Epstein-Barr virus and multiple sclerosis. It is believed that acute infection and viral reactivation promote the development of multiple sclerosis.Conclusions: It is necessary to conduct further research on the pathogenesis and morphophysiological and neuroimmunological changes –at the ecological, molecular, cellular, tissue, organic and systemic level– induced by the immune response and that favor the development of multiple sclerosis.

Myocarditis in Humans and in Experimental Animal Models

Myocarditis is defined as an inflammation of the cardiac muscle. In humans, various infectious and non-infectious triggers induce myocarditis with a broad spectrum of histological presentations and clinical symptoms of the disease. Myocarditis often resolves spontaneously, but some patients develop heart failure and require organ transplantation. The need to understand cellular and molecular mechanisms of inflammatory heart diseases led to the development of mouse models for experimental myocarditis. It has been shown that pathogenic agents inducing myocarditis in humans can often trigger the disease in mice. Due to multiple etiologies of inflammatory heart diseases in humans, a number of different experimental approaches have been developed to induce myocarditis in mice. Accordingly, experimental myocarditis in mice can be induced by infection with cardiotropic agents, such as coxsackievirus B3 and protozoan parasite Trypanosoma cruzi or by activating autoimmune responses against heart-specific antigens. In certain models, myocarditis is followed by the phenotype of dilated cardiomyopathy and the end stage of heart failure. This review describes the most commonly used mouse models of experimental myocarditis with a focus on the role of the innate and adaptive immune systems in induction and progression of the disease. The review discusses also advantages and limitations of individual mouse models in the context of the clinical manifestation and the course of the disease in humans. Finally, animal-free alternatives in myocarditis research are outlined.

T-cell recruitment to the heart: friendly guests or unwelcome visitors?

Myocardial inflammation can lead to lethal acute or chronic heart failure (HF). T lymphocytes (T cells), have been reported in the inflamed heart in different etiologies of HF, and more recent studies support that different T-cell subsets play distinct roles in the heart depending on the inflammation-triggering event. T cells follow sequential steps to extravasate into tissues, but their specific recruitment to the heart is determined by several factors. These include differences in T-cell responsiveness to specific chemokines in the heart environment, as well as differences in the expression of adhesion molecules in response to distinct stimuli, which regulate T-cell recruitment to the heart and have consequences in cardiac remodeling and function. This review focuses on recent advances in our understanding of the role T cells play in the heart, including its critical role for host defense to virus and myocardial healing postischemia, and its pathogenic role in chronic ischemic and nonischemic HF. We discuss a variety of mechanisms that contribute to the inflammatory damage to the heart, as well as regulatory mechanisms that limit the magnitude of T-cell-mediated inflammation. We also highlight areas in which further research is needed to understand the role T cells play in the heart and distinguish the findings reported in experimental animal models and how they may translate to clinical observations in the human heart.

ADAR1p150 Forms a Complex with Dicer to Promote miRNA-222 Activity and Regulate PTEN Expression in CVB3-Induced Viral Myocarditis

Adenosine deaminases acting on RNA (ADAR) are enzymes that regulate RNA metabolism through post-transcriptional mechanisms. ADAR1 is involved in a variety of pathological conditions including inflammation, cancer, and the host defense against viral infections. However, the role of ADAR1p150 in vascular disease remains unclear. In this study, we examined the expression of ADAR1p150 and its role in viral myocarditis (VMC) in a mouse model. VMC mouse cardiomyocytes showed significantly higher expression of ADAR1p150 compared to the control samples. Coimmunoprecipitation verified that ADAR1p150 forms a complex with Dicer in VMC. miRNA-222, which is involved in many cardiac diseases, is highly expressed in cardiomyocytes in VMC. In addition, the expression of miRNA-222 was promoted by ADAR1p150/Dicer. Among the target genes of miRNA-222, the expression of phosphatase-and-tensin (PTEN) protein was significantly reduced in VMC. By using a bioinformatics tool, we found a potential binding site of miRNA-222 on the PTEN gene’s 3′-UTR, suggesting that miRNA-222 might play a regulatory role. In cultured cells, miR-222 suppressed PTEN expression. Our findings suggest that ADAR1p150 plays a key role in complexing with Dicer and promoting the expression of miRNA-222, the latter of which suppresses the expression of the target gene PTEN during VMC. Our work reveals a previously unknown role of ADAR1p150 in gene expression in VMC.

Viral Infection of the Heart: Pathogenesis and Diagnosis

Viral infections of the heart cause serious clinical problems, either as infectious myocarditis, which usually is a consequence of acute infection or as idiopathic dilated cardiomyopathy, resulting rather from a chronic infection. This minireview presents an up-to-date view on pathomechanisms of viral infection of the heart tissues, the role of immune system in controlling infectious process at its various stages and current possibilities of recognizing viral infection of the heart with use of both cardiological and virological methods. Our goal was to present the variety of known viral agents causing heart infection, level of complexity in mutual virus-cell interactions, and consequent clinical scenarios.

TLR3 is required for survival following Coxsackievirus B3 infection by driving T lymphocyte activation and polarization: The role of dendritic cells

Type B coxsackievirus (CVB) is a common cause of acute and chronic myocarditis, meningitis and pancreatitis, often leading to heart failure and pancreatic deficiency. The polarization of CD4⁺ T lymphocytes and their cytokine milieu are key factors in the outcome of CVB-induced diseases. Thus, sensing the virus and driving the adaptive immune response are essential for the establishment of a protective immune response. TLR3 is a crucial virus recognition receptor that confers the host with resistance to CVB infection. In the current study, we found that TLR3 expression in dendritic cells plays a role in their activation upon CVB3 infection in vitro, as TLR3-deficient dendritic cells up-regulate CD80 and CD86 to a less degree than WT cells. Instead, they up-regulated the inhibitory molecule PD-L1 and secreted considerably lower levels of TNF-α and IL-10 and a higher level of IL-23. T lymphocyte proliferation in co-culture with CVB3-infected dendritic cells was increased by TLR3-expressing DCs and other cells. Furthermore, in the absence of TLR3, the T lymphocyte response was shifted toward a Th17 profile, which was previously reported to be deleterious for the host. TLR3-deficient mice were very susceptible to CVB3 infection, with increased pancreatic injury and extensive inflammatory infiltrate in the heart that was associated with uncontrolled viral replication. Adoptive transfer of TLR3⁺ dendritic cells slightly improved the survival of TLR-deficient mice following CVB3 infection. Therefore, our findings highlight the importance of TLR3 signaling in DCs and in other cells to induce activation and polarization of the CD4⁺ T lymphocyte response toward a Th1 profile and consequently for a better outcome of CVB3 infection. These data provide new insight into the immune-mediated mechanisms by which CVBs are recognized and cleared in order to prevent the development of myocarditis and pancreatitis and may contribute to the design of therapies for enteroviral infections.

CD4+ CD25+ GARP+ regulatory T cells display a compromised suppressive function in patients with dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a lethal inflammatory heart disease and closely connected with dysfunction of the immune system. Glycoprotein A repetitions predominant (GARP) expressed on activated CD4⁺ T cells with suppressive activity has been established. This study aimed to investigate the frequency and function of circulating CD4⁺  CD25⁺  GARP⁺ regulatory T (Treg) cells in DCM. Forty-five DCM patients and 46 controls were enrolled in this study. There was a significant increase in peripheral T helper type 1 (Th1) and Th17 number and their related cytokines [interferon-γ (IFN-γ), interleukin (IL-17)], and an obvious decrease in Treg number, transforming growth factor-β₁ (TGF-β₁ ) levels and the expression of forkhead box P3 (FOXP3) and GARP in patients with DCM compared with controls. In addition, the suppressive function of CD4⁺  CD25⁺  GARP⁺ Treg cells was impaired in DCM patients upon T-cell receptor stimulation detected using CFSE dye. Lower level of TGF-β₁ and higher levels of IFN-γ and IL-17 detected using ELISA were found in supernatants of the cultured CD4⁺  CD25⁺  GARP⁺ Treg cells in DCM patients compared with controls. Together, our results indicate that CD4⁺  CD25⁺  GARP⁺ Treg cells are defective in DCM patients and GARP seems to be a better molecular definition of the regulatory phenotype. Therefore, it might be an attractive stategy to pay more attention to GARP in DCM patients.

In vivo T2* weighted MRI visualizes cardiac lesions in murine models of acute and chronic viral myocarditis

Objective

Acute and chronic forms of myocarditis are mainly induced by virus infections. As a consequence of myocardial damage and inflammation dilated cardiomyopathy and chronic heart failure may develop. The gold standard for the diagnosis of myocarditis is endomyocardial biopsies which are required to determine the etiopathogenesis of cardiac inflammatory processes. However, new non-invasive MRI techniques hold great potential in visualizing cardiac non-ischemic inflammatory lesions at high spatial resolution, which could improve the investigation of the pathophysiology of viral myocarditis.

Results

Here we present the discovery of a novel endogenous T2* MRI contrast of myocardial lesions in murine models of acute and chronic CVB3 myocarditis. The evaluation of infected hearts ex vivo and in vivo by 3D T2w and T2*w MRI allowed direct localization of virus-induced myocardial lesions without any MRI tracer or contrast agent. T2*w weighted MRI is able to detect both small cardiac lesions of acute myocarditis and larger necrotic areas at later stages of chronic myocarditis, which was confirmed by spatial correlation of MRI hypointensity in myocardium with myocardial lesions histologically. Additional in vivo and ex vivo MRI analysis proved that the contrast mechanism was due to a strong paramagnetic tissue alteration in the vicinity of myocardial lesions, effectively pointing towards iron deposits as the primary contributor of contrast. The evaluation of the biological origin of the MR contrast by specific histological staining and transmission electron microscopy revealed that impaired iron metabolism primarily in mitochondria caused iron deposits within necrotic myocytes, which induces strong magnetic susceptibility in myocardial lesions and results in strong T2* contrast.

Conclusion

This T2*w MRI technique provides a fast and sensitive diagnostic tool to determine the patterns and the severity of acute and chronic enteroviral myocarditis and the precise localization of tissue damage free of MR contrast agents.

A Novel Murine Model of Parvovirus Associated Dilated Cardiomyopathy Induced by Immunization with VP1-Unique Region of Parvovirus B19

Background. Parvovirus B19 (B19V) is a common finding in endomyocardial biopsy specimens from myocarditis and dilated cardiomyopathy patients. However, current understanding of how B19V is contributing to cardiac damage is rather limited due to the lack of appropriate mice models. In this work we demonstrate that immunization of BALB/c mice with the major immunogenic determinant of B19V located in the unique sequence of capsid protein VP1 (VP1u) is an adequate model to study B19V associated heart damage. Methods and Results. We immunized mice in the experimental group with recombinant VP1u; immunization with cardiac myosin derived peptide served as a positive reference and phosphate buffered saline served as negative control. Cardiac function and dimensions were followed echocardiographically 69 days after immunization. Progressive dilatation of left ventricle and decline of ejection fraction were observed in VP1u- and myosin-immunized mice. Histologically, severe cardiac fibrosis and accumulation of heart failure cells in lungs were observed 69 days after immunization. Transcriptomic profiling revealed ongoing cardiac remodeling and immune process in VP1u- and myosin-immunized mice. Conclusions. Immunization of BALB/c mice with VP1u induces dilated cardiomyopathy in BALB/c mice and it could be used as a model to study clinically relevant B19V associated cardiac damage.

Takotsubo Cardiomyopathy and Sepsis

Takotsubo cardiomyopathy (TTC) is characterized by a systolic dysfunction localized in the apical and medial aspect of the left ventricle. It is usually related to physical or emotional stress. Recent evidence highlighting the role of infection led us to analyze the links between TTC and sepsis. A systematic review of the literature was undertaken to assess any trends in clinical findings, diagnosis, and outcomes in such patients. We identified 23 selected papers reporting a total of 26 patients, having sepsis, in whom TTC occurred. For each case, we collected data identifying population characteristics, source of sepsis, clinical disease description, and the results of cardiovascular investigations. The majority of patients were females (n = 16), mean age was 62.8 (14.0 standard deviation) years, and clinical outcome was favorable in 92.3% of the cases once the management of sepsis was initiated. A better understanding of the mechanisms of sepsis-associated TTC may generate novel strategies to treat the complications of this cardiomyopathy and may even help predict and prevent its occurrence.

A new monoclonal antibody (Cox mAB 31A2) detects VP1 protein of coxsackievirus B3 with high sensitivity and specificity

Human enteroviruses, e.g. coxsackieviruses, induce a variety of severe acute and chronic forms of disease, including myocarditis, meningitis and diabetes mellitus type 1. To visualize enterovirus infection with a diagnostic intent, many studies have applied a commercially available antibody (anti-CVB5 VP1, clone 5-D8/1, Dako, Hamburg, Germany) that identifies VP1 of different enteroviral serotypes. Many antibodies, however, have been found to bind non-specifically to proteins of cardiomyocytes and in the interstitial space, resulting in non-specific staining in immunohistochemistry. In this paper we show that the anti-CVB5 VP1 antibody, recognizing VP1 of coxsackieviruses and widely used in diagnostics and research, shows strong cross-reactivity with cellular proteins in the heart (and pancreas) of humans and mice, which calls for a more specific antibody to be used for diagnostic purposes. We observed by Western blot analyses of lysates from human heart tissue samples and HeLa cells two cross-reactive bands when using clone 5-D8/1. Peptide mass fingerprinting (MALDI-TOF) identified these proteins as creatine kinase (B-type) and tubulin, confirming that this mAb detects cellular proteins in addition to viral VP1. In order to overcome the problems of false positive VP1 staining we generated a new highly specific and sensitive monoclonal antibody (Cox mAB 31A2) that recognizes VP1 from CVB3. The new antibody was characterized and was found to function well in immunohistochemistry, immunofluorescence staining, Western blotting, ELISA and FACS analyses.

Dual roles of calpain in facilitating Coxsackievirus B3 replication and prompting inflammation in acute myocarditis

Background

Viral myocarditis (VMC) treatment has long been lacking of effective methods. Our former studies indicated roles of calpain in VMC pathogenesis. This study aimed at verifying the potential of calpain in Coxsackievirus B3 (CVB3)-induced myocarditis treatment.

Methods

A transgenic mouse overexpressing the endogenous calpain inhibitor, calpastatin, was introduced in the study. VMC mouse model was established via intraperitoneal injection of CVB3 in transgenic and wild mouse respectively. Myocardial injury was assayed histologically (HE staining and pathology grading) and serologically (myocardial damage markers of CK-MB and cTnI). CVB3 replication was observed in vivo and in vitro via the capsid protein VP1 detection or virus titration. Inflammation/fibrotic factors of MPO, perforin, IFNγ, IL17, Smad3 and MMP2 were evaluated using western blot or immunohistology stain. Role of calpain in regulating fibroblast migration was studied in scratch assays.

Results

Calpastatin overexpression ameliorated myocardial injury induced by CVB3 infection significantly in transgenic mouse indicated by reduced peripheral CK-MB and cTnI levels and improved histology injury. Comparing with CVB3-infected wild type mouse, the transgenic mouse heart tissue carried lower virus load. The inflammation factors of MPO, perforin, IFNγ and IL17 were down-regulated accompanied with fibrotic agents of Smad3 and MMP2 inhibition. And calpain participated in the migration of fibroblasts in vitro, which further proves its role in regulating fibrosis.

Conclusion

Calpain plays dual roles of facilitating CVB3 replication and inflammation promotion. Calpain inhibition in CVB3-induced myocarditis showed significant treatment effect. Calpain might be a novel target for VMC treatment in clinical practices.

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Calpain is involved in virus replication in myocarditis.

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Calpain mediates inflammation infiltration in myocarditis.

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Calpain might be a candidate for viral myocarditis treatment.

Inflammatory Cardiomyopathy: A Current View on the Pathophysiology, Diagnosis, and Treatment

Inflammatory cardiomyopathy is defined as inflammation of the heart muscle associated with impaired function of the myocardium. In our region, its etiology is most often viral. Viral infection is a possible trigger of immune and autoimmune mechanisms which contributed to the damage of myocardial function. Myocarditis is considered the most common cause of dilated cardiomyopathy. Typical manifestation of this disease is heart failure, chest pain, or arrhythmias. The most important noninvasive diagnostic method is magnetic resonance imaging, but the gold standard of diagnostics is invasive examination, endomyocardial biopsy. In a significant proportion of cases with impaired left ventricular systolic function, recovery occurs spontaneously in several weeks and therefore it is appropriate to postpone critical therapeutic decisions about 3–6 months after start of the treatment. Therapy is based on standard heart failure treatment; immunosuppressive or antimicrobial treatment may be considered in some cases depending on the results of endomyocardial biopsy. If severe dysfunction of the left ventricle persists, device therapy may be needed.