Viral myocarditis--diagnosis, treatment options, and current controversies

microRNA-34a aggravates coxsackievirus B3-induced apoptosis of cardiomyocytes through the SIRT1-p53 pathway

Viral myocarditis is inflammation of the myocardium mainly caused by a viral infection, and coxsackievirus B3 (CVB3) infection is one of the most common. It is well known that cardiomyocyte apoptosis is involved in the pathogenesis of viral myocarditis. microRNAs (miRNAs, miRs) are endogenous noncoding oligoribonucleotides involved in various pathological conditions, and miR-34a is one of the miRNAs causing apoptosis. Whether miR-34a participates in cardiomyocyte apoptosis during CVB3 infection and the underlying mechanisms is still unclear. In this in vitro study, we found that miR-34a expression increased in cardiomyocytes after CVB3 infection. Furthermore, we found that CVB3 infection augmented histone deacetylase 1 (HDAC1) and Bax expression while inhibiting sirtuin 1 (SIRT1) and Bcl-2 expression, along with the acetylated p53 (Ac-p53) upregulation in cardiomyocytes. The above-mentioned phenomenon was reversed by a miR-34a inhibitor after CVB3 infection. In addition, the Ac-p53 amount increased in CVB3-infected cardiomyocytes, and SRT1720 and trichostatin A (TSA) pretreatment decreased Ac-p53 levels. After pifithrin-α pretreatment of CVB3-infected cardiomyocytes, the protein expression level of HDAC1 decreased while that of SIRT1 increased. Moreover, miR-34a expression and CVB3-induced apoptosis of cardiomyocytes were attenuated by pretreatment with SRT1720, TSA, or pifithrin-α, accompanied with Bax downregulation and Bcl-2 upregulation. In summary, these data indicate that miR-34a induces cardiomyocyte apoptosis by downregulating SIRT1, and the activation of the SIRT1-p53 pathway contributes to CVB3-induced apoptosis of cardiomyocytes. Thus, miR-34a might serve as a potential therapeutic target because it promotes cardiomyocyte apoptosis through the SIRT1-p53 signaling pathway.

Protective functions of myricetin in LPS-induced cardiomyocytes H9c2 cells injury by regulation of MALAT1

BACKGROUND

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a crucial mediator in response to inflammation. Myricetin protects cardiomyocytes against inflammatory injury. However, it's still unexplored whether myricetin exerted anti-inflammatory properties via MALAT1. The purpose of our study was to validate the cardio-protective function of myricetin against myocarditis and its underlying mechanism in vitro.

METHODS

H9c2 cells were pre-incubated with myricetin before stimulation with lipopolysaccharide (LPS). Enforced silence of MALAT1 was achieved by transducing short hairpin (sh)-MALAT1 into H9c2 cells. Next, cell viability and apoptotic cells were detected with cell counting kit-8 (CCK-8) and Annexin V-fluorescein isothiocyanate/propidium iodide (Annexin V-FITC/PI) apoptosis detection kit, respectively. Western blot assay was conducted to examine apoptosis-relative proteins, pro-inflammatory factors, and signaling regulators. Quantitative real-time PCR (qRT-PCR) was performed to quantify pro-inflammatory factors and MALAT1 at mRNA levels. Enzyme-linked immune sorbent assay (ELISA) was employed to determine protein concentration of pro-inflammatory factors.

RESULTS

Myricetin ameliorated LPS-elicited reduction of cell viability, augment of apoptosis, and overexpression of monocyte chemo-attractant protein-1 (MCP-1) and interleukin-6 (IL-6) in H9c2 cells. Meanwhile, phosphorylation of p65 and inhibitor of nuclear factor kappa B alpha (IκBα) were suppressed. Besides, myricetin enhanced the expression of MALAT1 which was originally down-regulated by LPS. However, the protective effects of myricetin against LPS-caused inflammatory lesions were abrogated in MALAT1-deficiency cells, with the restored phosphorylation of p65 and IκBα.

CONCLUSION

Myricetin possessed an anti-inflammatory function against LPS-induced lesions in cardiomyocytes. Mechanically, myricetin up-regulated MALAT1, blocked LPS-evoked activation of nuclear factor-κB (NF-κB) inflammatory pathway, and, finally, exerted cardio-protective effects.

Extracellular SPARC increases cardiomyocyte contraction during health and disease

Secreted protein acidic and rich in cysteine (SPARC) is a non-structural extracellular matrix protein that regulates interactions between the matrix and neighboring cells. In the cardiovascular system, it is expressed by cardiac fibroblasts, endothelial cells, and at lower levels by ventricular cardiomyocytes. SPARC expression levels are increased upon myocardial injury and also during hypertrophy and fibrosis. We have previously shown that SPARC improves cardiac function after myocardial infarction by regulating post-synthetic procollagen processing, however whether SPARC directly affects cardiomyocyte contraction is still unknown. In this study we demonstrate a novel inotropic function for extracellular SPARC in the healthy heart as well as in the diseased state after myocarditis-induced cardiac dysfunction. We demonstrate SPARC presence on the cardiomyocyte membrane where it is co-localized with the integrin-beta1 and the integrin-linked kinase. Moreover, extracellular SPARC directly increases cardiomyocyte cell shortening ex vivo and cardiac function in vivo, both in healthy myocardium and during coxsackie virus-induced cardiac dysfunction. In conclusion, we demonstrate a novel inotropic function for SPARC in the heart, with a potential therapeutic application when myocyte contractile function is diminished such as that caused by a myocarditis-related cardiac injury.

Diagnostic performance of serum CK-MB, TNF-α and hs-CRP in children with viral myocarditis

Objective

The purpose of this study was to investigate the diagnostic performance of serum CK-MB, TNF-α and hs-CRP in children with viral myocarditis (VMC).

Methods

Fifty-six children with confirmed diagnosis of VMC were included in this study. Of the included 56 cases, 25 subjects were in acute and other 31 were in the recovery stage. A contemporaneous control group of 22 children were included for comparison. The serum concentration of CK-MB, TNF-α and hs-CRP were examined in both VMC and control groups.

Results

The serum concentration of CK-MB, TNF-α and hs-CRP were 31.77±9.48 (UL), 143.11±23.27 (ng/L) and 8.10±1.94(mg/L) for acute stage VMC; 12.72±4.99 (UL), 83.15±13.35 (ng/L) and 4.07±1.12 (mg/L) for recovery stage VMC; 8.11±3.20 (UL), 68.27±12.55 (ng/L) and 2.56±1.27 (mg/L) for control group respectively; The serum concentration of CK-MB, TNF-α and hs-CRP were significantly different between acute stage VMC, recovery stage VMC and control groups (p<0.05); Significant positive correlation between CK-MB and hs-CRP were found in acute stage VMC (r=0.54, p=0.01) and recovery stage VMC (r=0.37, p=0.04). Using serum CK-MB, TNF-α and hs-CRP as the reference, the differential diagnosis sensitivity for acute and recovery stage VMC were 87.10 (70.17-96.37)%, 87.10 (70.17-96.37)% and 77.42 (58.90-90.415)%; The specificity were 92.00 (73.97-99.02)%, 96.00 (79.65-99.90)% and 100.00 (86.28-100.00)% respectively.

Conclusion

Serum concentration of CK-MB, TNF-α and hs-CRP in children with VMC were significant increased especially in acute stage, which can be used as biomarkers for VMC diagnosis.

A life support-based comprehensive treatment regimen dramatically lowers the in-hospital mortality of patients with fulminant myocarditis: a multiple center study

Fulminant myocarditis (FM) has unacceptable high mortality. This study aimed to evaluate the therapeutic efficacy of a life support-based comprehensive treatment regimen (LSBCTR), a completely novel treatment regimen, for FM. A total of 169 FM patients recruited from January 2008 to December 2018 were divided into two groups: patients receiving LSBCTR (81 cases), which includes (i) mechanical life support (positive pressure respiration, intra-aortic balloon pump with or without extracorporeal membrane oxygenation), (ii) immunomodulation therapy using sufficient doses of glucocorticoids and immunoglobulins, and (iii) application of neuraminidase inhibitors, and those receiving conventional treatment (88 cases). The endpoints were in-hospital death and heart-transplantation. Of all the population, 44 patients (26.0%) died in hospitals. In-hospital mortality was 3.7% (3/81) for LSBCTR group and 46.6% (41/88) for traditional treatment (P<0.001). Early application of LSBCTR, mechanical life support, neuraminidase inhibitors, and immunomodulation therapy significantly contributed to reduction in in-hospital mortality. This study describes a novel treatment regimen for FM patients that dramatically reduces in-hospital mortality. Its generalization and clinical application will efficiently save lives although further optimization is needed. This study offers an insight that virus infection induced inflammatory waterfall results in cardiac injury and cardiogenic shock and is the therapeutic target.

Immunomodulatory treatment for lymphocytic myocarditis-a systematic review and meta-analysis

Deleterious inflammatory responses are seen to be the trigger of heart failure in myocarditis and therapies directed towards immunomodulation have been assumed to be beneficial. The objective of the present review was to systematically assess the effect of immunomodulation in lymphocytic myocarditis. Studies were included if diagnosis of lymphocytic myocarditis was based on EMB as well as on the exclusion of other etiologies of heart failure and if the patients had at least moderately decreased left ventricular ejection fraction (< 45%). All immunomodulatory treatments at any dose that target the cause of myocarditis leading to cardiomyopathy were included. Retrieval of PUBMED, SCOPUS, Cochrane Central Register of Controlled Trials, and LILACs from January 1950 to January 2016 revealed 444 abstracts of which nine studies with a total of 612 patients were included. As primary effectivity endpoint, a change in left ventricular ejection was chosen. No benefits of corticosteroids or intravenous immunoglobulin alone were reported. Immunoadsorption and subsequent IVIG substitution was associated with a greater improvement in left ventricular ejection fraction (LVEF) in one study. Single studies found a beneficial effect of interferon and statins on LVEF. We performed a meta-analysis for the combination of corticosteroids with immunosuppressants and found a non-significant increase of LVEF of + 13.06% favoring combined treatment (95%CI 1.71 to + 27.84%, p = 0.08). The current evidence does not support the routine use of immunosuppression in traditional lymphocytic myocarditis. Nevertheless, in histologically proven virus-negative myocarditis of high-risk patients, combined immunosuppression might be beneficial. Future research should focus on translation of these effects to clinical outcome.

Chinese society of cardiology expert consensus statement on the diagnosis and treatment of adult fulminant myocarditis

Fulminant myocarditis is primarily caused by infection with any number of a variety of viruses. It arises quickly, progresses rapidly, and may lead to severe heart failure or circulatory failure presenting as rapid-onset hypotension and cardiogenic shock, with mortality rates as high as 50%-70%. Most importantly, there are no treatment options, guidelines or an expert consensus statement. Here, we provide the first expert consensus, the Chinese Society of Cardiology Expert Consensus Statement on the Diagnosis and Treatment of Fulminant Myocarditis, based on data from our recent clinical trial (NCT03268642). In this statement, we describe the clinical features and diagnostic criteria of fulminant myocarditis, and importantly, for the first time, we describe a new treatment regimen termed life support-based comprehensive treatment regimen. The core content of this treatment regimen includes (i) mechanical life support (applications of mechanical respirators and circulatory support systems, including intraaortic balloon pump and extracorporeal membrane oxygenation, (ii) immunological modulation by using sufficient doses of glucocorticoid, immunoglobulin and (iii) antiviral reagents using neuraminidase inhibitor. The proper application of this treatment regimen may and has helped to save the lives of many patients with fulminant myocarditis.

Opportunities for microRNAs in the Crowded Field of Cardiovascular Biomarkers

Cardiovascular diseases exist across all developed countries. Biomarkers that can predict or diagnose diseases early in their pathogeneses can reduce their morbidity and mortality in afflicted individuals. microRNAs are small regulatory RNAs that modulate translation and have been identified as potential fluid-based biomarkers across numerous maladies. We describe the current state of cardiovascular disease biomarkers across a range of diseases, including myocardial infarction, acute coronary syndrome, myocarditis, hypertension, heart failure, heart transplantation, aortic stenosis, diabetic cardiomyopathy, atrial fibrillation, and sepsis. We present the current understanding of microRNAs as possible biomarkers in these categories and where their best opportunities exist to enter clinical practice.

Dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a clinical diagnosis characterized by left ventricular or biventricular dilation and impaired contraction that is not explained by abnormal loading conditions (for example, hypertension and valvular heart disease) or coronary artery disease. Mutations in several genes can cause DCM, including genes encoding structural components of the sarcomere and desmosome. Nongenetic forms of DCM can result from different aetiologies, including inflammation of the myocardium due to an infection (mostly viral); exposure to drugs, toxins or allergens; and systemic endocrine or autoimmune diseases. The heterogeneous aetiology and clinical presentation of DCM make a correct and timely diagnosis challenging. Echocardiography and other imaging techniques are required to assess ventricular dysfunction and adverse myocardial remodelling, and immunological and histological analyses of an endomyocardial biopsy sample are indicated when inflammation or infection is suspected. As DCM eventually leads to impaired contractility, standard approaches to prevent or treat heart failure are the first-line treatment for patients with DCM. Cardiac resynchronization therapy and implantable cardioverter-defibrillators may be required to prevent life-threatening arrhythmias. In addition, identifying the probable cause of DCM helps tailor specific therapies to improve prognosis. An improved aetiology-driven personalized approach to clinical care will benefit patients with DCM, as will new diagnostic tools, such as serum biomarkers, that enable early diagnosis and treatment.

Corticosteroids and Intravenous Immunoglobulin in Pediatric Myocarditis: A Meta-Analysis

Background: The efficacy of corticosteroids and intravenous immunoglobulin (IVIG) in pediatric myocarditis remains controversial. Objectives: The authors performed a meta-analysis to assess the therapeutic efficacy of corticosteroids and IVIG in children with myocarditis. Methods: We retrieved the trials on corticosteroids and IVIG therapy, respectively, in pediatric myocarditis from nine databases up to December 2018. Statistical analysis was performed using Review Manager 5.3. Results: Our analysis included 8 studies and 334 pediatric patients. The data demonstrated that children receiving corticosteroids showed no significant improvement on left ventricular ejection fraction (LVEF) from 1 to 8 month-follow-up (MD = 5.17%, 95% CI = -0.26% to 10.60%, P = 0.06), and no significant improvement in death or heart transplantation incidence at the end of follow-up (OR = 1.33, 95% CI = 0.27-6.70, P = 0.73). However, children receiving IVIG revealed a statistically remarkable increase in LVEF at a follow-up over the course of 6 months to 1 year (MD = 18.91%, 95% CI = 11.74-26.08%, P < 0.00001), and a decrease in death or heart transplantation at the end of follow-up (OR = 0.31, 95% CI = 0.12-0.75, P = 0.01). Further comparisons showed that the mortality and heart transplantation rate of children with myocarditis treated with IVIG were significantly lower than those with corticosteroid therapy (t' = 11.336, P < 0.001). Conclusions: IVIG might be beneficial to improve LVEF and survival for myocarditis in children. However, the present evidence does not support corticosteroids as superior to conventional therapy in children with myocarditis. Further randomized controlled trials with a larger sample size are required.

Artificial cardiac pacemaker placement in dogs with a cohort of myocarditis suspects and association of ultrasensitive cardiac troponin I with survival

INTRODUCTION

Artificial cardiac pacemakers (APs) are a common treatment for symptomatic bradyarrhythmias in dogs, some of which may be triggered by underlying myocarditis. Severely elevated cardiac troponin I (cTnI) concentrations support a diagnosis of myocarditis. The association of ultrasensitive-cTnI (US-cTnI) concentration with survival in a large cohort of dogs receiving APs is not described.

ANIMALS, MATERIALS, AND METHODS

The study included 110 dogs receiving APs over a 5-year period. Medical records were retrospectively reviewed to characterize the entire population receiving APs, with further analysis in dogs with preprocedural US-cTnI concentrations (n = 64) classified as normal/group 1 (n = 11), mildly to moderately elevated/group 2 (n = 27), and severely elevated/myocarditis suspects/group 3 (n = 26).

RESULTS

Median survival time was 1079 days for the entire population, 1167 days for group 2, 949 days for group 3, and not met in group 1. There was not a statistically significant difference in survival between group 2 and group 3. Overall, US-cTnI had a mild, negative association with survival. Age had a stronger negative association. Infectious etiologies were identified in a minority of group 3 cases. A possible association between severely elevated US-cTnI and a sudden death outcome was noted.

CONCLUSIONS

The negative association of US-cTnI with survival outcomes was mild, with age having a larger effect. Although a sudden death outcome may be seen more commonly in myocarditis suspects, group 3 survival time was similar to that of the entire canine population. Plausible infectious causes of myocarditis were infrequently identified.

Influenza Myocarditis Treated With Antithymocyte Globulin

Influenza is a cause of significant morbidity and mortality worldwide. Myocarditis is a rare complication of the virus and can vary widely in severity. The published cases of influenza B myocarditis in children tend to be severe with a high mortality rate. Current standard treatment of viral myocarditis is supportive care, although immunomodulatory therapies, such as steroids and intravenous immunoglobulin, are often used. T cells have been implicated in causing significant myocyte damage in myocarditis by leading to the downstream production of antibodies against viral and myocyte antigens; this has created a theoretical basis for the use of antithymocyte globulin to target T cells in these patients. We present a case of acute fulminant influenza B myocarditis in a pediatric patient that required mechanical circulatory support and improved only after treatment with antithymocyte globulin.

Identification of potential pathogenic viruses in patients with acute myocarditis using next-generation sequencing

Myocarditis is an inflammatory disease of the myocardium and leads to cardiac dysfunction and heart failure. Although viral infections are considered to be the most common etiology of myocarditis, the identification of the causative virus is still challenging. Recently, next-generation sequencing (NGS) has been applied in the diagnosis of infectious diseases. The aim of the current study was to comprehensively analyze potential pathogenic microorganisms using NGS in the sera of patients with myocarditis. Twelve pediatric and five adult patients hospitalized for acute myocarditis were included. Serum samples in the acute phase were obtained and analyzed using NGS to detect pathogen-derived DNA and RNA. Viral sequence reads were detected in 7 (41%) of the 17 myocarditis patients by NGS. Among these patients, detection of Epstein-Barr virus, human parvovirus B19, torque teno virus, and respiratory syncytial virus reads by NGS was consistent with polymerase chain reaction or antigen test results in one patient each. A large number of human pegivirus reads were detected from one patient by RNA sequencing; however, its pathogenicity to human is unknown. Conversely, the number of detected virus-derived reads was small in most cases, and the pathophysiological role of these viruses remains to be clarified. No significant bacterial or fungal reads other than normal bacterial flora was detected. These data indicate that comprehensive detection of virus-derived DNA and RNA using NGS can be useful for the identification of potential pathogenic viruses in myocarditis.

Geniposide Attenuates LPS-Induced Injury via Up-Regulation of miR-145 in H9c2 Cells

Myocarditis is a cardiomyopathy associated with inflammatory response. It has been reported that geniposide (GEN), a traditional Chinese herb extract from Gardenia jasminoides Ellis, possesses an anti-inflammatory effect and a protective effect on cardiomyocytes. The present study aimed to explore the protective role of GEN and the underlying mechanism in LPS-injured H9c2 cells. H9c2 cells were treated with LPS to induce cell injury and then we investigated the effect of GEN. miR-145 expression was inhibited by transfection with miR-145 inhibitor and its expression was measured by RT-PCR. Cell viability and apoptotic cells were measured by CCK-8 assay and flow cytometry analysis. The levels of pro-inflammatory factors (IL-6, TNF-α, and MCP-1) were assessed by western blot and RT-PCR. Western blot was performed to detect the expression of the MEK/ERK pathway-related factors. LPS exposure reduced cell viability, increased apoptotic cells, and promoted the expression of pro-inflammatory factors in H9c2 cells. However, GEN pretreatment significantly reduced LPS-induced cell injury, as increased cell viability, reduced apoptotic cells, and inhibited the expression of pro-inflammatory factors. Moreover, we found that miR-145 expression was down-regulated by LPS exposure but was up-regulated by GEN pretreatment. The protective effect of GEN on LPS-injured H9c2 cells was blocked by miR-145 inhibitor. In addition, GEN inhibited the MEK/ERK pathway through up-regulating miR-145. Our results suggested that GEN exerted a protective role in LPS-injured H9c2 cells. The GEN-associated regulation might be related to its regulation on miR-145 and the MEK/ERK signaling pathway.

Nox4-dependent ROS production is involved in CVB3-induced myocardial apoptosis

Viral myocarditis is a cardiovascular disease that seriously affects human health. Its mechanism is not clear. Coxsackievirus B3 (CVB3) is a member of the picornavirus family and is the leading cause of viral myocarditis. Our group tested the genes in a mouse model of CVB3 virus infection and confirmed that the NADPH oxidase gene had a high expression trend in the acute phase of infection. Whether Nox4, the homologue of NADPH oxidase, participates in the process of viral myocarditis has not been reported. In this study, we found increased expression of Nox4 in viral myocarditis in vivo and in vitro. DPI is a non-specific inhibitor of Nox4 that improved CVB3-induced myocarditis after injection in vivo. DPI also inhibited intracellular ROS release and apoptosis in vitro. Our data indicated that Nox4-dependent ROS production was involved in CVB3-induced myocardial apoptosis.

Cross-platform metabolic profiling deciphering the potential targets of Shenfu injection against acute viral myocarditis in mice

Acute viral myocarditis (AVMC) is typically caused by cardiotropic viral infection. There is a paucity of specific treatment options available with proven efficacy. Chinese patented pharmaceutical product Shenfu injection (SFI) has potent efficacy on treating AVMC in clinical practice. However, the molecular mechanism is still unknown. We employed cross-platform metabolomics combined with computational systems analysis, based on reversed-phase liquid chromatography-mass spectrometry (RPLC-MS), hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS) and gas chromatography-mass spectrometry (GC-MS), to deciphering the targeted metabolic pathways of SFI against AVMC induced by coxsackievirus B3 (CVB3). Quantitative real-time PCR (qRT-PCR) technique was further applied to determining the expressions of the key genes associated with the SFI-targeted metabolic pathways. We have identified 48 significantly changed metabolites related to CVB3-induced AVMC, and SFI can significantly regulate the abnormalities of 33 metabolites and 9 relevant enzymes. Combined metabolic pathway enrichment and topology analyses revealed that the mechanisms of SFI against CVB3-induced AVMC may be attributed to modulating the disordered homeostasis of sphingolipid metabolism, glycerophospholipid metabolism, arachidonic acid metabolism, tryptophan metabolism, and TCA cycle. It provides new experimental information on the pathogenesis of AVMC, unravels the potential targeted metabolic pathways of SFI against AVMC on the whole metabolic network and highlights the importance of metabolomics combined with computational systems analysis as a potential tool for deciphering drug-targeted metabolic pathways.

Astragalus Root dry extract restores connexin43 expression by targeting miR-1 in viral myocarditis

BACKGROUND

Viral myocarditis is defined as viral infection of myocardial tissue leading to impaired heart function and heart failure. Accumulating evidences have shown that arrhythmia is one of important complicating diseases of viral myocarditis causing increased mortality and morbidity. There are no effective treatment for the viral infection and complicating arrhythmia.

PURPOSE

This study investigated the effect and mechanism of Astragalus Root dry extract (ARDE) on arrhythmia induced by CVB3 in mice.

METHODS

The mice and HL-1 cells were treated with CVB3 and ARDE. Reciprocal regulation of Cx43 and miR-1 were observed in the CVB3 infected mouse myocardium and culture HL-1 cells.

RESULTS

CVB3 IP injection increased immune cell infiltration in mouse left ventricle and caused irregular arrhythmia. ARDE treatment prevented the increase of immune cell infiltration and arrhythmia. Overexpression of miR-1 significantly inhibited both endogenous Cx43 expression and Cx43 3'UTR luciferase activity in HL-1 cells. Mutation of census binding site of +1586-1593 bp not +465-472 bp in Cx43 3'UTR luciferase resulted in abolishment of miR-1 inhibitory effects in HL-1 cells. Loss-of- function of miR-1 restored CVB3-induced Cx43 expression reduction in cultured HL-1 cells. The presence of ARDE attenuated the augmented miR-1 induced by CVB3 infection in vivo and in vitro.

CONCLUSION

This study identified that CVB3 infection reduced Cx43 expression by elevating miR-1 level in mouse viral myocarditis. For the first time, ARDE was shown to prevent arrhythmia, and rescue CVB3-induced endogenous Cx43 expression by regulating miR-1 level.

The Role of Necroptosis in Cardiovascular Disease

A newly discovered mechanism of cell death, programmed necrosis (necroptosis), combines features of both necrosis and apoptosis. Necroptosis is tightly modulated by a series of characteristic signaling pathways. Activating necroptosis by ligands of death receptors requires the kinase activity of receptor-interacting protein 1 (RIP1), which mediates the activation of receptor-interacting protein 3 (RIP3) and mixed lineage kinase domain-like (MLKL) two critical downstream mediators of necroptosis. Recently, different cytokines have been found participating in this mechanism of cell death. Necroptosis has been proposed as an important component to the pathophysiology of heart disease such as vascular atherosclerosis, ischemia-reperfusion injury, myocardial infarction and cardiac remodeling. Targeting necroptosis signaling pathways may provide therapeutic benefit in the treatment of cardiovascular diseases.

The Prevalence and Findings of Subclinical Influenza-associated Cardiac Abnormalities among Japanese Patients

Objective Although life-threatening cardiac complications in influenza infection are rare, subclinical influenza-associated cardiac abnormalities may occur more frequently. We investigated the prevalence of subclinical cardiac findings. Methods After obtaining their written informed consent, 102 subjects were enrolled in the present study. The study subjects underwent a first set of examinations, which included electrocardiography (ECG), echocardiography, and the measurement of their cardiac enzyme levels. Those with one or more abnormal findings among these examinations were encouraged to undergo a repeat examination 2 weeks later. Results Among the 102 subjects enrolled, 22 (21.6%) were judged to have cardiac findings, including ST-T abnormalities, pericardial effusion, diastolic dysfunction, and cardiac enzyme elevation. Eighteen of these 20 subjects underwent a second screening at a median of 14 days later, and it was found that 11 of the 18 subjects were free from cardiac findings on this second examination. This suggested that the abnormalities were only transient and they therefore might have been associated with influenza. Approximately 20% of the influenza patients enrolled had cardiac findings, including ST-T segment abnormalities, pericardial effusion, and cardiac enzyme elevation. Conclusion Among the 102 patients who were studied, the cardiac findings were only mild and transient; however, physicians should be aware of influenza infection-associated cardiac abnormalities because such abnormalities may not be rare.

Gr-1+ Cells Other Than Ly6G+ Neutrophils Limit Virus Replication and Promote Myocardial Inflammation and Fibrosis Following Coxsackievirus B3 Infection of Mice

Coxsackievirus B3 (CVB3) is the primary cause of viral myocarditis. An early and abundant neutrophil accumulation in the myocardium is a hallmark of early CVB3 infection. Yet the relative contribution of neutrophils to host susceptibility to CVB3 myocarditis remains largely unknown. Herein, peripheral neutrophil depletion was implemented in a BALB/c mouse model of acute CVB3 myocarditis using the specific 1A-8 (anti-Ly6G) or a RB6-8C5 (anti-Gr-1) mAb covering a wide range. Anti-Ly6G treatment led to systemic neutropenia throughout the disease, but did not alter virus replication, disease susceptibility and histopathological changes in the heart and pancreas of mice. In contrast, depletion of both neutrophils and monocytes/macrophages by anti-Gr-1 mAb prior to and after infection significantly promoted susceptibility of mice to CVB3 infection which was associated with exacerbated cardiac and pancreatic viral load. However, depletion of Gr1+ cells significantly suppressed acute myocarditis and pancreatic acini destruction at day 7 post infection via reducing Ly6C^high monocyte population in the circulation. Additionally, cardiac interstitial fibrosis was not affected by neutrophil depletion, whereas Gr-1+ cells other than neutrophils increased cardiac fibrosis at day 21 p.i. by increasing cardiac expression of profibrotic cytokine TNF-α and TGF-β. Thus, Neutrophil function is most likely not essential for CVB3 control and peripheral neutrophils play dispensable role in the pathogenesis of acute myocarditis and pancreatitis during CVB3 infection. Whereas Gr-1+ cells other than neutrophils play a major role in limiting viral replication while promoting myocardial and pancreatic inflammatory injury and fibrosis.

Progranulin ameliorates coxsackievirus-B3-induced viral myocarditis by downregulating Th1 and Th17 cells

Viral myocarditis, which is caused by Coxsackievirus B3 (CVB3) infection, is a leading reason of sudden cardiac death in young adults. Progranulin (PGRN), a pleiotropic growth factor, has been shown to exert anti-inflammatory function in a variety of inflammatory diseases. However, the expression and function of PGRN in the pathogenesis of viral myocarditis remain largely unknown. In this study, we found that PGRN levels in plasma and cardiac tissues were significantly upregulated post CVB3 infection, and negative correlated with disease severity. PGRN deficiency significantly exacerbated, whereas recombinant PGRN treatment attenuated CVB3-induced myocarditis in mice. PGRN downregulated Th1 and Th17 cell responses and cytokine production in vitro and in vivo, whereas its effect on viral myocarditis was Treg cell independent. Furthermore, PGRN regulated Th1 and Th17 cells differentiation through inhibition of the JAK/STAT pathway. Therefore, our findings reveal a critical role for PGRN in reducing CVB3-induced myocarditis and suggest that PGRN maybe a novel therapeutic treatment for viral myocarditis.

Intramyocardial inflammation predicts adverse outcome in patients with cardiac AL amyloidosis

AIMS

To evaluate the influence of endomyocardial biopsy (EMB)-proven intramyocardial inflammation on mortality in patients with cardiac transthyretin amyloid (ATTR) or amyloid light-chain (AL) amyloidosis.

METHODS AND RESULTS

We included 54 consecutive patients (mean age 68.83 ± 9.59 years; 45 men) with EMB-proven cardiac amyloidosis. We followed up patients from first diagnostic biopsy to as long as 36 months (mean 11.5 ± 12 months) and compared their outcome with information on all-cause mortality with or without proof of inflammation on EMB. Intramyocardial inflammation was assessed by quantitative immunohistology. Patients suffering from amyloidosis revealed a significant poor prognosis with proof of intramyocardial inflammation in contrast to those without inflammation (log-rank P = 0.019). Re-grouping of patients indicated AL amyloidosis to have a significant impact on all-cause mortality (log-rank P = 0.012). The detailed subgroup analysis showed that patients suffering from AL amyloidosis with intramyocardial inflammation have a significantly worse prognosis compared with AL amyloidosis without inflammation and ATTR with or without inflammation, respectively (log-rank P = 0.014, contingency Fisher's exact test, P = 0.008).

CONCLUSION

Our study reports for the first time a high incidence (48.1%) of intramyocardial inflammation in a series of patients with EMB-proven cardiac amyloidosis and could show that in patients with AL amyloidosis, intramyocardial inflammation correlated significantly with increased mortality. Our data have a direct clinical impact because one can hypothesize that additional immunomodulating/anti-inflammatory treatment regimens in patients with biopsy-proven inflammation of heart muscle tissue could be beneficial for patients suffering from cardiac AL amyloidosis.

Cytomegalovirus myocarditis in a patient with systemic lupus erythematosus (SLE) successfully treated with ganciclovir

Myocarditis is an inflammatory disease of the myocardium. Viruses, such as enterovirus, adenovirus, parvovirus B19, HHV6 or cytomegalovirus (CMV) and autoimmune diseases are recognized causes of myocarditis. We describe the clinical case of a young Indian woman with SLE and a concomitant acute CMV related myocarditis with favourable outcome after ganciclovir therapy. CMV myocarditis may range from being a subclinical infection with incidental findings on ECG to a life threating presentation. There are no trials demonstrating the efficacy of antiviral therapy in myocarditis. Case series of patients with CMV myocarditis have reported an excellent clinical outcome after antiviral agents. Lupus Myocarditis (LM) is more prevalent in young females. There are no specific ECG or echocardiographic signs. Treatment strategies of LM are based on corticosteroids, immunosuppressive agents and cardiovascular support, usually with a favorable prognosis, but LM often lead to a severe clinical picture, with mortality of 10.3%. Endomyocardial biopsy (EBM) is recommended as the gold standard but it is very underused in clinical practice, It should be performed in a specialized center but there are concerns on lack of specificity, low negative predictive value, risk of complication, and sampling errors due to the focal nature of myocarditis. Both SLE and CMV are potentially responsible of acute myocarditis. In our knowledge, CMV myocarditis with SLE was described in only one other patient. The initiation of antiviral therapy improved the clinical picture and, in our opinion, it is mandatory when CMV related life threating conditions develop.

Non-invasive differentiation of idiopathic inflammatory myopathy with cardiac involvement from acute viral myocarditis using cardiovascular magnetic resonance imaging T1 and T2 mapping

BACKGROUND

Idiopathic inflammatory myopathy (IIM) is a group of autoimmune diseases with systemic myositis which may involve the myocardium. Cardiac involvement in IIM, although often subclinical, may mimic clinical manifestations of acute viral myocarditis (AVM). Our aim was to investigate the usefulness of the combined analysis of cardiovascular magnetic resonance (CMR) T1 and T2 mapping parameters measured both in the myocardium and in the thoracic skeletal muscles to differentiate AVM from IIM cardiac involvement.

METHODS

Sixty subjects were included in this retrospective study (36 male, age 45 ± 16 years): twenty patients with AVM, twenty patients with IIM and cardiac involvement and twenty healthy controls. Study participants underwent CMR imaging with modified Look-Locker inversion-recovery (MOLLI) T1 mapping and 3-point balanced steady-state-free precession T2 mapping. Relaxation times were quantified after endocardial and epicardial delineation on basal and medial short-axis slices, as well as in different thoracic skeletal muscle groups present in the CMR field-of-view. ROC-Analysis was performed to assess the ability of mapping indices to discriminate the study groups.

RESULTS

Mapping parameters in the thoracic skeletal muscles were able to discriminate between AVM and IIM patients. Best skeletal muscle parameters to identify IIM from AVM patients were reduced post-contrast T1 and increased extracellular volume (ECV), resulting in an area under the ROC curve (AUC) of 0.95 for post-contrast T1 and 0.96 for ECV. Conversely, myocardial mapping parameters did not discriminate IIM from AVM patients but increased native T1 (AUC 0.89 for AVM; 0.84 for IIM) and increased T2 (AUC 0.82 for AVM; 0.88 for IIM) could differentiate both patient groups from healthy controls.

CONCLUSION

CMR myocardial mapping detects cardiac inflammation in AVM and IIM compared to normal myocardium in healthy controls but does not differentiate IIM from AVM. However, thoracic skeletal muscle mapping was able to accurately discern IIM from AVM.

Cathepsin B aggravates coxsackievirus B3-induced myocarditis through activating the inflammasome and promoting pyroptosis

Cathepsin B (CatB) is a cysteine proteolytic enzyme widely expressed in various cells and mainly located in the lysosomes. It contributes to the pathogenesis and development of many diseases. However, the role of CatB in viral myocarditis (VMC) has never been elucidated. Here we generated the VMC model by intraperitoneal injection of coxsackievirus B3 (CVB3) into mice. At day 7 and day 28, we found CatB was significantly activated in hearts from VMC mice. Compared with the wild-type mice receiving equal amount of CVB3, genetic ablation of CatB (Ctsb^-/-) significantly improved survival, reduced inflammatory cell infiltration, decreased serum level of cardiac troponin I, and ameliorated cardiac dysfunction, without altering virus titers in hearts. Conversely, genetic deletion of cystatin C (Cstc^-/-), which markedly enhanced CatB levels in hearts, distinctly increased the severity of VMC. Furthermore, compared with the control, we found the inflammasome was activated in the hearts of wild-type mice with VMC, which was attenuated in the hearts of Ctsb^-/- mice but was further enhanced in Cstc^-/- mice. Consistently, the inflammasome-initiated pyroptosis was reduced in Ctsb^-/- mice hearts and further increased in Cstc^-/- mice. These results suggest that CatB aggravates CVB3-induced VMC probably through activating the inflammasome and promoting pyroptosis. This finding might provide a novel strategy for VMC treatment.

Severe VMC could lead to sudden cardiac death especially in youths, and is also the most common cause of secondary dilated cardiomyopathy. However, we still lack effective and specific clinical treatments currently. Therefore, further exploration of the pathogenesis and new therapeutic targets are urgently needed. Our results implied that CatB, a cysteine protease mainly located in the lysosome, is activated in the hearts of mice with VMC induced by intraperitoneal injection of CVB3. Genetic deletion of CatB significantly improves survival, attenuates cardiac inflammation, decreases serum cardiac troponin I levels and alleviates cardiac dysfunction, without altering virus titers in hearts. However, ablation of its main endogenous inhibitor, cystatin C, distinctly exaggerates the disease severity. Mechanistically, we found that CatB influences VMC probably by activating the NLRP3 inflammasome and promoting caspase-1-induced pyroptosis. This may provide a potential new therapeutic strategy for VMC.

The Optimal Intervention Time of Bone Marrow Mesenchymal Stem Cells in Ameliorating Cardiac Fibrosis Induced by Viral Myocarditis: A Randomized Controlled Trial in Mice

Bone marrow-derived mesenchymal stem cells (BMSCs) have recently been introduced to treat cardiovascular diseases, such as myocardial infarction and dilated cardiomyopathy. Nevertheless, there are few researches focused on the application of BMSCs in treating viral myocarditis, not to mention its optimal intervention timer potential mechanisms. In our study, we concentrated on finding an optimal time window to perform BMSCs treatment in a murine model of myocarditis induced by coxsackievirus B3 (CVB3). On the 1st day, 3rd day, 7th day, and 14th day after BALB/c mice were infected by CVB3, we intravenously injected equivalent BMSCs into the treatment groups. With a 28-day follow-up after inoculation, we found that the ventricular function was significantly improved in the BMSCs treatment group and cardiac fibrosis markedly ameliorated, especially when BMSCs were injected between 1 and 2 weeks after CVB3 inoculation. Furthermore, we demonstrated that after BMSCs treatment, the expressions of TGF-β, col1α1, and col3α1 were significantly decreased. Therefore, we conclude that BMSCs may have a potential to improve CVB3-induced myocarditis by ameliorating cardiac fibrosis through the inhibition of TGF-β expression.

Eosinophilic Myocarditis: Characteristics, Treatment, and Outcomes

BACKGROUND

Eosinophilic myocarditis (EM) is an acute life-threatening inflammatory disease of the heart. Neither large case series nor clinical trials on this specific myocarditis have been reported.

OBJECTIVES

Based on a systematic revision of all published histologically proven cases, this study aimed to describe the clinical presentation, treatment, and outcome of EM.

METHODS

The study screened 443 manuscripts in MEDLINE and EMBASE on cases of EM published until June 2017. The authors identified 264 patients and included in the main analysis 179 patients admitted to hospital with histologically proven EM.

RESULTS

Median age was 41 years (interquartile range: 27 to 53 years) with similar prevalence in both sexes; pediatric cases (≤16 years of age) accounted for 10.1%. The main symptom at presentation was dyspnea (59.4%), with peripheral eosinophilia observed in 75.9%. Median left ventricular ejection fraction at presentation was 35% (interquartile range: 25% to 50%). The disorders most frequently associated with EM were hypersensitivity and eosinophilic granulomatosis with polyangiitis, which accounted for 34.1% and 12.8% of cases, respectively, whereas idiopathic or undefined forms accounted for 35.7% of cases. Steroids were administered in 77.7% of patients. A temporary mechanical circulatory support (n = 30) was instituted in 16.8% of patients. In-hospital death was 22.3% (n = 40), with the highest occurrence in the hypersensitivity form (36.1%; p = 0.026).

CONCLUSIONS

EM has a poor prognosis during the acute phase, despite a publication bias that could have led to an overestimation of mortality. Associated conditions are identified in approximately 65% of cases. Specific trials and multicenter registries are needed to provide evidence-based treatments to improve in-hospital outcome.

Necroptosis may be a novel mechanism for cardiomyocyte death in acute myocarditis

In this study, we investigated the roles of RIP1/RIP3 mediated cardiomyocyte necroptosis in CVB3-induced acute myocarditis. Serum concentrations of creatinine kinase (CK), CK-MB, and cardiac troponin I were detected using a Hitachi Automatic Biochemical Analyzer in a mouse model of acute VMC. Histological changes in cardiac tissue were observed by light microscope and expression levels of RIP1/RIP3 in the cardiac tissue were detected via Western blot and immunohistochemistry. The data showed that RIP1/RIP3 was highly expressed in cardiomyocytes in the acute VMC mouse model and that the necroptosis pathway specific blocker, Nec-1, dramatically reduced the myocardial damage by downregulating the expression of RIP1/RIP3. These findings provide evidence that necroptosis plays a significant role in cardiomyocyte death and it is a major pathway for cell death in acute VMC. Blocking the necroptosis pathway may serve as a new therapeutic option for the treatment of acute viral myocarditis.

High Perforin-Positive Cardiac Cell Infiltration and Male Sex Predict Adverse Long-Term Mortality in Patients With Inflammatory Cardiomyopathy

BACKGROUND

The authors analyzed the effects of perforin-dependent infiltration on long-term mortality in patients with inflammatory cardiomyopathy (CMi). We previously demonstrated that left ventricular function deteriorates and progresses to substantial cardiac dysfunction in patients with perforin-positive cardiac cell infiltration.

METHODS AND RESULTS

Between 2003 and 2013, 2389 consecutive patients with clinically suspected CMi who underwent endomyocardial biopsies were enrolled. Endomyocardial biopsies were performed at first admission after exclusion of ischemic or valvular heart disease, and CMi was confirmed in 1717 patients. Follow-up was up to 10.1 years (median 0.47 years; interquartile range, 0.03-2.56 years) and information on vital status was obtained from official resident data files. Multivariable statistical analysis was conducted for all patients with CMi regarding significant predictors of all-cause mortality or need for heart transplantation. Multiple Cox regression analysis revealed perforin above the calculated cutoff point of 2.9 cells/mm² as a strong predictor of impaired survival with a hazard ratio of 1.881 (95% confidence interval, 1.177-3.008; P=0.008), independent of left ventricular function and other myocardial inflammation markers (CD3, macrophage-1 antigen, leukocyte function-associated antigen-1, human leukocyte antigen-1, and intercellular cell adhesion molecule-1). Unexpectedly, male sex emerged as another strong adverse predictor of survival in CMi (hazard ratio, 1.863; confidence interval, 1.096-3.168 [P=0.022]). Whereas left ventricular ejection fraction course is adversely affected by myocardial perforin, multivariate analysis indicates that left ventricular ejection fraction explains only part of the observed overall mortality.

CONCLUSIONS

High perforin-positive cardiac cell infiltration and male sex are independent adverse predictors of long-term mortality in CMi. Furthermore, exact quantification of immunohistochemically detected infiltrates is necessary to assess the prognosis.

Interleukin-13 reduces cardiac injury and prevents heart dysfunction in viral myocarditis via enhanced M2 macrophage polarization

Viral myocarditis is one of the major causes of congestive heart failure and dilated cardiomyopathy. Recent reports have demonstrated an essential role of cytokines, like interleukin-13 (IL-13), in the pathogenesis of viral myocarditis, while the underlying mechanisms remain poorly defined. Here, using a coxsackie virus B3 (CVB3)-infection model in BALB/C mice, we showed that IL-13 protected mouse heart function in viral myocarditis, seemingly through reduction in T lymphocyte immunity and induction of M2 macrophage polarization. Adoptive transfer to M2 macrophages mimicked the effects of IL-13 on protection from myocarditis, suggesting that the effects of IL-13 may be primarily through regulation of macrophage polarization. Together, our data suggest that application of IL-13 treatment may reduce cardiac Injury and protect heart function in viral myocarditis via enhanced M2 macrophage polarization.

Performance of Cardiac Magnetic Resonance Imaging for Diagnosis of Myocarditis Compared with Endomyocardial Biopsy: A Meta-Analysis

Background

Cardiac magnetic resonance imaging (CMRI) is considered to be useful for the diagnosis of myocarditis, and the Lake Louise Criteria (LLC) has been proved to be of significance as the standard of diagnosis. However, the diagnostic performance of LLC-based CMRI for myocarditis compared with endomyocardial biopsy (EMB) has not been quantitatively evaluated in a meta-analysis.

Material/Methods

The databases PubMed, Cochrane’s Library, and EMBASE were searched to identify studies on LLC and its individual components for the diagnosis of myocarditis. EMB was the control reference. The sensitivity, specificity, and positive and negative diagnostic likelihood ratios were calculated with a random-effects model. The area under the receiver operating characteristic curve (AUC) was estimated to show overall effectiveness.

Results

We included 9 cohorts (614 patients) of patients with suspected MC. The combined sensitivities, specificities, and AUCs for T1-weighed global relative enhancement were 0.66, 0.73, and 0.71; for T2-weighed edema ratio they were 0.52, 0.73, and 0.72; for the late gadolinium enhancement, they were 0.70, 0.57, and 0.67; and for LLC-based CMRI they were 0.70, 0.56, and 0.70, respectively. Subgroup analysis indicated that the sensitivities, specificities, and diagnostic accuracies of LLC and its individual component-based CMRI seemed to be similar in patients with acute or chronic myocarditis. Results of the Deeks’ funnel plot asymmetry test showed no significant publication bias among the studies.

Conclusions

CMRI based on LLC or its individual components seems to have moderate accuracy in diagnosis of acute or chronic myocarditis.

Autosomal Recessive Cardiomyopathy Presenting as Acute Myocarditis

BACKGROUND

Myocarditis is inflammation of the heart muscle that can follow various viral infections. Why children only rarely develop life-threatening acute viral myocarditis (AVM), given that the causal viral infections are common, is unknown. Genetic lesions might underlie such susceptibilities. Mouse genetic studies demonstrated that interferon (IFN)-α/β immunity defects increased susceptibility to virus-induced myocarditis. Moreover, variations in human TLR3, a potent inducer of IFNs, were proposed to underlie AVM.

OBJECTIVES

This study sought to evaluate the hypothesis that human genetic factors may underlie AVM in previously healthy children.

METHODS

We tested the role of TLR3-IFN immunity using human induced pluripotent stem cell-derived cardiomyocytes. We then performed whole-exome sequencing of 42 unrelated children with acute myocarditis (AM), some with proven viral causes.

RESULTS

We found that TLR3- and STAT1-deficient cardiomyocytes were not more susceptible to Coxsackie virus B3 (CVB3) infection than control cells. Moreover, CVB3 did not induce IFN-α/β and IFN-α/β-stimulated genes in control cardiomyocytes. Finally, exogenous IFN-α did not substantially protect cardiomyocytes against CVB3. We did not observe a significant enrichment of rare variations in TLR3- or IFN-α/β-related genes. Surprisingly, we found that homozygous but not heterozygous rare variants in genes associated with inherited cardiomyopathies were significantly enriched in AM-AVM patients compared with healthy individuals (p = 2.22E-03) or patients with other diseases (p = 1.08E-04). Seven of 42 patients (16.7%) carried rare biallelic (homozygous or compound heterozygous) nonsynonymous or splice-site variations in 6 cardiomyopathy-associated genes (BAG3, DSP, PKP2, RYR2, SCN5A, or TNNI3).

CONCLUSIONS

Previously silent recessive defects of the myocardium may predispose to acute heart failure presenting as AM, notably after common viral infections in children.

Survival and Left Ventricular Function Changes in Fulminant Versus Nonfulminant Acute Myocarditis

BACKGROUND

Previous reports have suggested that despite their dramatic presentation, patients with fulminant myocarditis (FM) might have better outcome than those with acute nonfulminant myocarditis (NFM). In this retrospective study, we report outcome and changes in left ventricular ejection fraction (LVEF) in a large cohort of patients with FM compared with patients with NFM.

METHODS

The study population consists of 187 consecutive patients admitted between May 2001 and November 2016 with a diagnosis of acute myocarditis (onset of symptoms <1 month) of whom 55 required inotropes and/or mechanical circulatory support (FM) and the remaining 132 were hemodynamically stable (NFM). We also performed a subanalysis in 130 adult patients with acute viral myocarditis and viral prodrome within 2 weeks from the onset, which includes 34 with FM and 96 with NFM. Patients with giant-cell myocarditis, eosinophilic myocarditis, or cardiac sarcoidosis and those <15 years of age were excluded from the subanalysis.

RESULTS

In the whole population (n=187), the rate of in-hospital death or heart transplantation was 25.5% versus 0% in FM versus NFM, respectively (P<0.0001). Long-term heart transplantation-free survival at 9 years was lower in FM than NFM (64.5% versus 100%, log-rank P<0.0001). Despite greater improvement in LVEF during hospitalization in FM versus NFM forms (median, 32% [interquartile range, 20%-40%] versus 3% [0%-10%], respectively; P<0.0001), the proportion of patients with LVEF <55% at last follow-up was higher in FM versus NFM (29% versus 9%; relative risk, 3.32; 95% confidence interval, 1.45-7.64, P=0.003). Similar results for survival and changes in LVEF in FM versus NFM were observed in the subgroup (n=130) with viral myocarditis. None of the patients with NFM and LVEF ≥55% at discharge had a significant decrease in LVEF at follow-up.

CONCLUSIONS

Patients with FM have an increased mortality and need for heart transplantation compared with those with NFM. From a functional viewpoint, patients with FM have a more severely impaired LVEF at admission that, despite steep improvement during hospitalization, remains lower than that in patients with NFM at long-term follow-up. These findings also hold true when only the viral forms are considered and are different from previous studies showing better prognosis in FM.

Cardiovascular PET/MR imaging: Quo Vadis?

With the recent advent of PET/MRI scanners, the combination of molecular imaging with a variety of known and novel PET radiotracers, the high spatial resolution of MRI, and its potential for multi-parametric imaging are anticipated to increase the diagnostic accuracy in cardiovascular disease detection, while providing novel mechanistic insights into the initiation and progression of the disease state. For the time being, cardiac PET/MRI emerges as potential clinical tool in the identification and characterization of infiltrative cardiac diseases, such as sarcoidosis, acute or chronic myocarditis, and cardiac tumors, respectively. The application of PET/MRI in conjunction with various radiotracer probes in the identification of the vulnerable atherosclerotic plaque also holds much promise but needs further translation and validation in clinical investigations. The combination of molecular imaging and creation of multi-parametric imaging maps with PET/MRI, however, are likely to set new horizons to develop predictive parameters for myocardial recovery and treatment response in ischemic and non-ischemic cardiomyopathy patients. Molecular imaging and multi-parametric imaging in cardiovascular disease with PET/MRI at current stage are at its infancy but bear a bright future.

Detection and Monitoring of Acute Myocarditis Applying Quantitative Cardiovascular Magnetic Resonance

BACKGROUND

Cardiovascular magnetic resonance based on the Lake Louise Criteria is used to make the diagnosis of acute myocarditis. Novel quantitative parametric mapping techniques promise to overcome some of its limitations. We aimed to evaluate quantitative cardiovascular magnetic resonance to detect and monitor acute myocarditis.

METHODS AND RESULTS

Eighteen patients with clinical diagnosis of acute myocarditis (25 years [23-38 years]; 78% males) were prospectively enrolled and repeatedly underwent cardiovascular magnetic resonance at 1.5 T seven days (5-10 days) after symptom onset (FU0), after 5 weeks (FU1), and after 6 months (FU2). Eighteen age- and sex-matched healthy subjects served as controls. Cardiovascular magnetic resonance included imaging of edema, hyperemia, necrosis, and fibrosis using semiquantitative T2-weighted spin echo, T2 mapping, and T1 mapping before and 3 and 10 minutes after gadobutrol administration. Extracellular volume for diffuse and late gadolinium enhancement for focal fibrosis were assessed. Compared with controls, patients had significantly higher global T2 times at FU0 (55.1 ms [53.3-57.2 ms] versus 50.2 ms [49.2-52.0 ms]; P<0.001) and at FU1 (52.0 ms [52.0-53.2 ms]; P=0.007), which normalized at FU2 (50.9 ms [49.6-53.3 ms]; P=0.323). Global native T1 times in patients were elevated acutely (1004 ms [988-1048 ms] versus 975 ms [957-1004 ms]; P=0.002) and remained elevated throughout the follow-up (FU1: 998 ms [990-1027 ms]; P=0.014; FU2: 1000 ms [972-1027 ms]; P=0.044). Global extracellular volume fraction was statistically not different between patients and controls (P=0.057). 77.8% (14/18) of patients had focal late gadolinium enhancement. T2 ratio was significantly elevated in patients with myocarditis at FU0 (2.2 [2.0-2.3] versus 1.6 [1.5-1.7]; P<0.001). The difference decreased during follow-up (FU1: 1.9 [1.7-1.9]; P=0.001 and FU2: 1.7 [1.7-1.8]; P=0.053). The diagnostic accuracy to discriminate between patients with acute myocarditis and healthy controls was 86% for T2>52 ms, 78% for native T1>981 ms, 74% for extracellular volume fraction >0.24, and 100% for T2 ratio >1.9.

CONCLUSIONS

Although both T2 and T1 mapping reliably detected acute myocarditis, only T2 mapping discriminated between acute and healed stages, underlining the incremental value of T2 mapping.

Cardiac Autoimmunity: Myocarditis

Myocarditis is the inflammation of the muscle tissues of the heart (myocardium). After a pathologic cardiac-specific inflammatory process, it may progress to chronic damage and dilated cardiomyopathy. The latter is characterized by systolic dysfunction, whose clinical correlate is heart failure. Nevertheless, other acute complications may arise as consequence of tissue damage and electrophysiologic disturbances. Different etiologies are involved in triggering myocarditis. In some cases, such as giant cell myocarditis or eosinophilic necrotizing myocarditis, it is an autoimmune process. Several factors predispose the development of autoimmune myocarditis such as systemic/local primary autoimmunity, viral infection, HLA and gender bias, exposure of cryptic antigens, mimicry, and deficient thymic training/Treg induction. Once the anti-myocardium autoimmune process is triggered, several components of the immune response orchestrate a sustained attack toward myocardial tissues with particular timing and immunopathogenic features. Innate response mediated by monocytes/macrophages, neutrophils, and eosinophils parallels the adaptive response, playing a final effector role and not only a priming function. Stromal cells like fibroblast are also involved in the process through specific cytokines. Furthermore, adaptive T cell responses have anti-paradigmatic features, as Th17 response is dispensable for acute myocarditis but is the main driver of the process leading to dilated cardiomyopathy. Humoral response, thought to be a bystander, is important in the appearance of late-stage hemodynamic complications. The complexity of that process, as well as the unspecific and variable clinical presentation, had generated difficulties for diagnosis and treatment, which remain suboptimal. In this chapter, we will discuss the most relevant immunopathogenic findings from a basic science and clinical perspective.

Natural killer cells in inflammatory heart disease

Despite of a multitude of excellent studies, the regulatory role of natural killer (NK) cells in the pathogenesis of inflammatory cardiac disease is greatly underappreciated. Clinical abnormalities in the numbers and functions of NK cells are observed in myocarditis and inflammatory dilated cardiomyopathy (DCMi) as well as in cardiac transplant rejection [1-6]. Because treatment of these disorders remains largely symptomatic in nature, patients have little options for targeted therapies [7,8]. However, blockade of NK cells and their receptors can protect against inflammation and damage in animal models of cardiac injury and inflammation. In these models, NK cells suppress the maturation and trafficking of inflammatory cells, alter the local cytokine and chemokine environments, and induce apoptosis in nearby resident and hematopoietic cells [1,9,10]. This review will dissect each protective mechanism employed by NK cells and explore how their properties might be exploited for their therapeutic potential.

Established and novel treatment options in acute myocarditis, with or without heart failure

INTRODUCTION

Acute myocarditis is a disorder characterized by an unpredictable clinical course which ranges from asymptomatic, incidentally discovered forms, to cases with fulminant course and adverse outcome. The most challenging issues in the context of acute myocarditis are the appearance of difficult to treat heart failure in the acute phase and the potential progression in the long-term to dilated cardiomyopathy. Areas covered: With respect to available treatment options in acute myocarditis, in the absence of specific guidelines, management is supportive and overall empirical, especially for the oligo- or asymptomatic patients with preserved ejection fraction. Haemodynamically instable patients should be treated in referral centers with capability of advanced cardiopulmonary support. Patients with heart failure but without haemodynamic impairment should be treated according to the heart failure guidelines. Endomyocardial biopsy may be performed in an individualized basis both for diagnostic purposes and to guide treatment, based on the detection or not of viral genome. Expert commentary: Apart from the already established treatments, novel therapies against several targets are currently investigated and are expected to contribute to a more efficacious management options in the future. Increased awareness among medical professionals is essential for the early diagnosis and best care of acute myocarditis patients.

MicroRNA-98 plays a critical role in experimental myocarditis

BACKGROUND AND AIMS

Myocarditis is inflammation in the heart; its pathogenesis is to be further investigated. Activities of micro RNAs (miR) are associated with immune inflammation. This study tests a hypothesis that miR-98 is involved in the development of myocarditis.

METHODS

BALB/c mice were immunized with cardiac α-myosin heavy chain peptides (MyHC-α) to induce myocarditis. The effects of miR-98 on regulation of interleukin (IL)-10 were assessed by real time RT-PCR.

RESULTS

Mice immunized with MyHC-α showed myocarditis and lower frequency of IL-10⁺ B cells (B10 cell) in the hearts. Expression of miR-98 was higher, IL-10 was lower, in B cells isolated from the mouse hearts with myocarditis, which was negatively correlated with each other. Exposure to tumor necrosis factor-α up regulated miR-98 expression in B cells. Over-expression of miR-98 suppressed IL-10 expression in B cells. Blocking miR-98 or adoptively transplanting B10 cells attenuated experimental myocarditis.

CONCLUSIONS

miR-98 suppresses IL-10 expression in B cells in the heart, which plays an important role in myocarditis. MiR-98 may be a therapeutic target in the treatment of myocarditis.

Myocarditis in Paediatric Patients: Unveiling the Progression to Dilated Cardiomyopathy and Heart Failure

Myocarditis is a challenging and potentially life-threatening disease associated with high morbidity in some paediatric patients, due to its ability to present as an acute and fulminant disease and to ultimately progress to dilated cardiomyopathy. It has been described as an inflammatory disease of the myocardium caused by diverse aetiologies. Viral infection is the most frequent cause of myocarditis in developed countries, but bacterial and protozoal infections or drug hypersensitivity may also be causative agents. The prompt diagnosis in paediatric patients is difficult, as the spectrum of clinical manifestation can range from no myocardial dysfunction to sudden cardiac death. Recent studies on myocarditis pathogenesis have revealed a triphasic nature of this disease, which influences the diagnostic and therapeutic strategies to adopt in each patient. Endomyocardial biopsy remains the gold standard for diagnosing myocarditis, and several non-invasive diagnostic tools can be used to support the diagnosis. Intravenous immunoglobulin has become part of routine practice in the treatment of myocarditis in paediatric patients at many centres, but its true effect on the cardiac function has been the target of many studies. The aim of this review is to approach the recently discovered facets of paediatric myocarditis regarding its progression to dilated cardiomyopathy.