Myocarditis

Soluble Vascular Cell Adhesion Molecule-1 (VCAM-1) as a Biomarker in the Mouse Model of Experimental Autoimmune Myocarditis (EAM)

Vascular cell adhesion molecule-1 (VCAM-1) is strongly upregulated in hearts of mice with coxsackie virus-induced as well as in patients with viral infection-triggered dilated cardiomyopathy. Nevertheless, the role of its soluble form as a biomarker in inflammatory heart diseases remains unclear. Therefore, we investigated whether plasma levels of soluble VCAM-1 (sVCAM-1) directly correlated with disease activity and progression of cardiac dysfunction in the mouse model of experimental autoimmune myocarditis (EAM). EAM was induced by immunization of BALB/c mice with heart-specific myosin-alpha heavy chain peptide together with complete Freund`s adjuvant. ELISA revealed strong expression of cardiac VCAM-1 (cVCAM-1) throughout the course of EAM in immunized mice compared to control animals. Furthermore, sVCAM-1 was elevated in the plasma of immunized compared to control mice at acute and chronic stages of the disease. sVCAM-1 did not correlate with the degree of acute cardiac inflammation analyzed by histology or cardiac cytokine expression investigated by ELISA. Nevertheless, heart to body weight ratio correlated significantly with sVCAM-1 at chronic stages of EAM. Cardiac systolic dysfunction studied with positron emission tomography indicated a weak relationship with sVCAM-1 at the chronic stage of the disease. Our data provide evidence that plasma levels of sVCAM-1 are elevated throughout all stages of the disease but showed no strong correlation with the severity of EAM.

Sudden, unexpected death of a 15-year-old boy due to pancarditis: A case report and possible etiopathogenesis

BACKGROUND

Generally, rheumatic heart disease is, today, sporadic in developed countries, even though it continues to be a major health hazard in the developing ones. It is also a very rare cause of sudden unexpected death. We report a case of a 15-year-old boy who suddenly died at home. Since 3 days he had presented fever and chest pain. The family physician had diagnosed bronchitis and treated the boy with amoxicillin.

METHODS

Seven hours after death, a forensic autopsy were performed . Before the autopsy, anamnesis and some circumstantial data were collected from the boy's parents. During the autopsy, samples for histological, toxicological and molecular examinations were collected. The samples for the histology (brain, hypophysis, heart and pericardium, lungs, spleen, liver, kidney, adrenal glands) were formalin fixed and paraffin embedded. Each section was stained with Hematoxylin-Eosin. Immunostaining was also performed, with anti-CD 68, anti-CD3, anti-CD 20, anti-myeloperoxidase. Microbiological cultures were performed on cardiac blood, myocardium, pericardial effusion and cerebrospinal fluid samples collected during autopsy. Blood specimens were also processed through PCR, in order to reveal the presence of Enteroviruses, Chickenpox virus, Epstein Barr virus. Also chemical-toxicological examinations for the detection of the main medications and drugs were performed on blood samples.

RESULTS

The anamnesis, collected before the autopsy, revealed an acute pharyngitis few weeks before. The autopsy, and the following histological and immunochemical examinations suggested an immunological etiology. The immunohistochemistry, showing a strong positivity of antiCD68 antibodies, integrated with clinical-anamnestic information, leads to hypothesize a rheumatic carditis.

CONCLUSION

In light of this case, at least 3 main messages of great importance for the clinician can be deduced. First, an accurate anamnesis collected by the family physician could have led to the correct interpretation of the objective signs and the administration of an appropriate therapy. Second, a pharyngeal swab should be performed for cases involving sore throat in young children and adolescents, especially in cases involving repeated pharyngitis. Finally, apparently unremarkable findings revealed from objective examinations can be signs of a serious disease. Moreover, in some cases, these diseases can be lethal if they are not properly treated.

Use of the Impella 5.0 Device as a Bridge to Recovery in Adult Fulminant Viral Myocarditis

We present a case of a 48-year-old female patient successfully bridged to recovery with the Impella 5.0 microaxial pump (Abiomed, Danvers, MA USA) after presenting with cardiogenic shock secondary to acute fulminant viral myocarditis. After 1 week of flu-like symptoms, the patient presented to her community emergency department with chest pain and hypotension. A diagnosis of inferior ST elevation myocardial infarction was made; subsequent angiography demonstrated normal coronary arteries and a left ventricular ejection fraction of 10%. A provisional diagnosis of viral myocarditis was made. As her condition deteriorated further, she underwent insertion of an Impella 5.0 after failure of supportive medical therapy. Myocardial recovery occurred, and the Impella was removed after 1 week. After a prolonged cardiac intensive care unit stay requiring temporary hemodialysis, the patient recovered sufficiently to tolerate device explant, transfer to the recovery ward, and ultimate discharge home. This case report highlights the benefit of mechanical circulatory support in a patient with cardiogenic shock from viral myocarditis as well as some of the complications that can occur in this critically ill subset of patients.

Inhalant-Abuse Myocarditis Diagnosed by Cardiac Magnetic Resonance

Multiple reports of toxic myocarditis from inhalant abuse have been reported. We now report the case of a 23-year-old man found to have toxic myocarditis from inhalation of a hydrocarbon. The diagnosis was made by means of cardiac magnetic resonance imaging with delayed enhancement. The use of cardiac magnetic resonance to diagnose myocarditis has become increasingly common in clinical medicine, although there is not a universally accepted criterion for diagnosis. We appear to be the first to document a case of toxic myocarditis diagnosed by cardiac magnetic resonance. In patients with a history of drug abuse who present with clinical findings that suggest myocarditis or pericarditis, cardiac magnetic resonance can be considered to support the diagnosis.

MicroRNA-19b Downregulates Gap Junction Protein Alpha1 and Synergizes with MicroRNA-1 in Viral Myocarditis

Viral myocarditis (VMC) is a life-threatening disease that leads to heart failure or cardiac arrhythmia. A large number of researches have revealed that mircroRNAs (miRNAs) participate in the pathological processes of VMC. We previously reported that miR-1 repressed the expression of gap junction protein α1 (GJA1) in VMC. In this study, miR-19b was found to be significantly upregulated using the microarray analysis in a mouse model of VMC, and overexpression of miR-19b led to irregular beating pattern in human cardiomyocytes derived from the induced pluripotent stem cells (hiPSCs-CMs). The upregulation of miR-19b was associated with decreased GJA1 in vivo. Furthermore, a miR-19b inhibitor increased, while its mimics suppressed the expression of GJA1 in HL-1 cells. When GJA1 was overexpressed, the miR-19b mimics-mediated irregular beating was reversed in hiPSCs-CMs. In addition, the effect of miR-19b on GJA1 was enhanced by miR-1 in a dose-dependent manner. These data suggest miR-19b contributes to irregular beating through regulation of GJA1 by cooperating with miR-1. Based on the present and our previous studies, it could be indicated that miR-19b and miR-1 might be critically involved in cardiac arrhythmia associated with VMC.

Exercise-Triggered Chest Pain as an Isolated Symptom of Myocarditis in Children

In childhood, chest pain occurring at exercise is a common complaint. A cardiac etiology for it is exceptionally found, explaining that most children do not undergo systematic cardiological investigation. However, chest pain at exercise may manifest as the unique symptom of a viral myocarditis. Recognizing this form of myocardial injury, however, might help to avoid clinical deterioration by providing adequate care. In this paper, we report on two children presenting with the unique clinical symptom of chest pain related to physical activity and in whom laboratory and cardiac investigations suggested transient myocardial damage related to myocarditis.

Relationship between T-wave inversion and transmural myocardial edema as evidenced by cardiac magnetic resonance in patients with clinically suspected acute myocarditis: clinical and prognostic implications

BACKGROUND

The pathophysiologic mechanisms and the prognostic meaning of electrocardiographic (ECG) T-wave inversion (TWI) occurring in a subgroup of patients with clinically suspected acute myocarditis remain to be elucidated. Contrast-enhanced cardiac magnetic resonance (CMR) offers the potential to identify myocardial tissue changes such as edema and/or fibrosis which may underlie TWI.

METHODS AND RESULTS

We studied 76 consecutive patients (median age 34years) with clinically suspected acute myocarditis, using a comprehensive CMR protocol which included T2 weighted sequences for myocardial edema. At the time of CMR, TWI was observed in 21 (27%) patients. There was a statistically significant association of TWI with the median number of left ventricular (LV) segments showing both any pattern of myocardial edema (transmural and non-transmural) [5 (3-7) vs. 3 (2-4); p=0.015] and myocardial late-gadolinium-enhancement [4 (3-7) vs. 3 (2-4); p=0.002]. Transmural myocardial edema involving ≥2 LV segments was found in 17/21 (81%) patients with TWI versus 13/55 (24%) patients without TWI (p<0.001) and remained the only independent predictor of TWI at multivariable analysis (OR=9.96; 95%CI=2.71-36.6; p=0.001). Overall, topographic concordance between the location of TWI across the ECG leads and the regional distribution of transmural myocardial edema was 88%. There was no association between acute TWI and reduced LV ejection fraction (<55%) at 6-months of follow-up.

CONCLUSIONS

This is the first study to demonstrate an association between LV transmural myocardial edema as evidenced by CMR sequences and TWI in clinically suspected acute myocarditis. As an expression of reversible myocardial edema, development of TWI during the acute disease phase was not a predictor of LV systolic dysfunction at follow-up.

Virus-inhibiting activity of dihydroquercetin, a flavonoid from Larix sibirica, against coxsackievirus B4 in a model of viral pancreatitis

Members of the family Picornaviridae, in particular, enteroviruses, represent a serious threat to human health. They are responsible for numerous pathologies ranging from mild disease to fatal outcome. Due to the limited number of safe and effective antivirals against enteroviruses, there is a need for search and development of novel drugs with various mechanisms of activity against enteroviruses-induced pathologies. We studied the effect of dihydroquercetin (DHQ), a flavonoid from larch wood, on the course of pancreatitis of white mice caused by coxsackievirus B4 (CVB4). DHQ was applied intraperitoneally at doses of 75 or 150 mg/kg/day once a day for 5 days postinfection (p.i.) starting on day 1 p.i., and its effect was compared to that of the reference compound ribavirin. The application of DHQ resulted in a dose-dependent decrease in the virus titer in pancreatic tissue, reaching, at the highest dose, 2.4 logs on day 5 p.i. Also, the application of DHQ led to restoration of antioxidant activity of pancreatic tissue that was impaired in the course of pancreatitis. Morphologically, pancreatic tissue of DHQ-treated animals demonstrated less infiltration with inflammatory cells and no signs of tissue destruction compared to placebo-treated mice. Both ribavirin- and DHQ-treated animals developed fewer foci of pancreatic inflammation per mouse, and these foci contained fewer infiltrating cells than those in placebo-treated mice. The effect of DHQ was comparable to or exceeded that of ribavirin. Taken together, our results suggest high antiviral activity of DHQ and its promising potential in complex treatment of viral pancreatitis.

Role of coxsackievirus and adenovirus receptor (CAR) expression and viral load of adenovirus and enterovirus in patients with dilated cardiomyopathy

Enteroviruses (EVs) and adenoviruses (AdVs) are two important etiological agents of viral myocarditis and dilated cardiomyopathy (DCM). Both these viruses share a common receptor, the coxsackievirus and adenovirus receptor (CAR), for their infection. However, the role of viral load and CAR expression in disease severity has not yet been completely elucidated. The present study aimed to determine viral load of EV and AdV in DCM patients and correlate them with the level of CAR expression in these patients. Sixty-three DCM cases and 30 controls, each of whom died of heart disease other than DCM and non-cardiac disease respectively, were included. Viral load was determined by TaqMan real-time PCR using primers and probes specific for the AdV hexon gene and the 5'UTR region of EV. The CAR mRNA level was semi-quantitated by RT-PCR, and antigen expression was studied by immunohistochemistry. A significantly high AdV load (p < 0.05) and CAR expression (p < 0.05) were observed in DCM cases versus controls, whereas the EV load showed no significant difference. The data suggests a clinical threshold of 128 AdV copies/500 ng of DNA for DCM, with 66.7 % sensitivity and 65 % specificity. A positive correlation between AdV load and CAR expression (p < 0.001) was also observed in DCM cases. The high adenoviral load and increased CAR expression in DCM and their association with adverse disease outcome indicates role of both virus and receptor in disease pathogenesis. Thus, the need for targeting both the virus and the receptor for treatment of viral myocarditis and early DCM requires further confirmation with larger studies.

New-Onset Myocarditis in an Immunocompetent Adult with Acute Metapneumovirus Infection

Introduction. A number of viruses have been implicated in viral myocarditis; however, there has been no previous report of human metapneumovirus (hMPV) causing this condition. Discovered in 2001, hMPV is typically associated with upper respiratory illness, mainly affecting children. Case Presentation. We report the case of a 25-year-old man with acute systolic heart failure from viral myocarditis secondary to the hMPV. The patient was initially admitted to the general medical ward but developed increasing oxygen requirements resulting in transfer to the cardiac intensive care unit. Cardiac magnetic resonance imaging was used to help confirm the diagnosis. He was treated with intravenous diuretics, and afterload and preload agents, and he was subsequently discharged home after seven days of hospitalization. Discussion. hMPV is typically a respiratory pathogen; however, it was associated with in myocarditis in our patient. Due to the recent ability to detect this virus, we may see more cases of this, particularly during peak months of infection. Conclusion. This is the first case description of myocarditis associated with hMPV infection.

Cardiovascular magnetic resonance predictors of clinical outcome in patients with suspected acute myocarditis

BACKGROUND

The natural history of acute myocarditis (AM) remains highly variable and predictors of outcome are largely unknown. The objectives were to determine the potential value of various cardiovascular magnetic resonance (CMR) parameters for the prediction of adverse long-term outcome in patients presenting with suspected AM.

METHODS

In a single-centre longitudinal prospective study, 203 routine consecutive patients with an initial CMR-based diagnosis of AM (typical Late Gadolinium Enhancement, LGE) were followed over a mean period of 18.9 ± 8.2 months. Various CMR parameters were evaluated as potential predictors of outcome. The primary endpoint was defined as the occurrence of at least one of the combined Major Adverse Clinical Events (MACE) (cardiac death or aborted sudden cardiac death, cardiac transplantation, sustained documented ventricular tachycardia, heart failure, recurrence of acute myocarditis, and the need for hospitalization for cardiac causes).

RESULTS

The vast majority of patients (N = 143,70 %) presented with chest pain, mild to moderate troponin elevation and ST-segment or T wave abnormalities. Various CMR parameters were evaluated on initial CMR performed 3 ± 2 days after acute clinical presentation (LV functional parameters, presence/extent of edema on T2 CMR, and extent of late gadolinium enhancement lesions). Out of the 203 patients, 22 experienced at least one major cardiovascular event (10.8 %) during follow-up for a total of 31 major cardiovascular events. Among all CMR parameters, the only independent CMR predictor of adverse clinical outcome by multivariate analysis was an initial alteration of LVEF (p = 0.04).

CONCLUSIONS

In routine consecutive patients without severe hemodynamic compromise and a CMR-based diagnosis of AM, various CMR parameters such as the presence and extent of myocardial edema and the extent of late gadolinium-enhanced LV myocardial lesions were not predictive of outcome. The only independent CMR predictor of adverse clinical outcome was an initial alteration of LVEF.

Idiopathic giant cell myocarditis in childhood: A case report

Idiopathic giant cell myocarditis is a rare entity of unknown origin, which causes sudden death in more than half of the affected patients. It is rarely seen in childhood, and might result in death due to heart failure and ventricular arrhythmias. Idiopathic giant cell myocarditis is mostly diagnosed at autopsy incidentally. Here we present a rare case of childhood idiopathic giant cell myocarditis. A 10-year old boy found dead in his bed in the morning. Interview with family members revealed death the boy was in good health conditions apart from being overweight. At autopsy, external examination was completely normal. Internal examination revealed normal findings; the heart was 297g and macroscopically normal. No traces of any toxic agents detected in complete toxicological analyses. Areas characterized with granulomatous lesions, lymphocytes, histiocytes, and multinucleated giant cells were observed in myocardium at histopathological examination. No necrosis was observed in granulomatous areas. Tuberculosis was negative in the PCR assays. There were no signs indicative of fungal infection, and clinical status of the case was not compatible with the sarcoidosis. In this respect death was attributed to idiopathic giant cell myocarditis.

The microRNA-221/-222 cluster balances the antiviral and inflammatory response in viral myocarditis

Aims

Viral myocarditis (VM) is an important cause of heart failure and sudden cardiac death in young healthy adults; it is also an aetiological precursor of dilated cardiomyopathy. We explored the role of the miR-221/-222 family that is up-regulated in VM.

Methods and results

Here, we show that microRNA-221 (miR-221) and miR-222 levels are significantly elevated during acute VM caused by Coxsackievirus B3 (CVB3). Both miRs are expressed by different cardiac cells and by infiltrating inflammatory cells, but their up-regulation upon myocarditis is mostly exclusive for the cardiomyocyte. Systemic inhibition of miR-221/-222 in mice increased cardiac viral load, prolonged the viraemic state, and strongly aggravated cardiac injury and inflammation. Similarly, in vitro, overexpression of miR-221 and miR-222 inhibited enteroviral replication, whereas knockdown of this miR-cluster augmented viral replication. We identified and confirmed a number of miR-221/-222 targets that co-orchestrate the increased viral replication and inflammation, including ETS1/2, IRF2, BCL2L11, TOX, BMF, and CXCL12. In vitro inhibition of IRF2, TOX, or CXCL12 in cardiomyocytes significantly dampened their inflammatory response to CVB3 infection, confirming the functionality of these targets in VM and highlighting the importance of miR-221/-222 as regulators of the cardiac response to VM.

Conclusions

The miR-221/-222 cluster orchestrates the antiviral and inflammatory immune response to viral infection of the heart. Its inhibition increases viral load, inflammation, and overall cardiac injury upon VM.

Heart Failure in Chronic Myocarditis: A Role for microRNAs?

Myocarditis is an inflammatory disease of the heart, which can persist over a long time. During this time, known as the chronic phase of myocarditis, ongoing inflammation damages the cardiomyocytes. The loss of cardiac cells culminates in the development of dilated cardiomyopathy, often followed by non-ischemic heart failure due to diminished cardiac function. During the course of the disease, expression levels of non-coding small RNAs, called microRNAs (miRNAs), change. Although mainly studied in the acute setting, some of these changes in expression level appear to persist in the chronic phase. In addition to being a much-needed diagnostic tool, these miRNA could provide new treatment options. miRNA-based intervention strategies already showed promising results in the treatment of ischemic cardiovascular diseases in preclinical animal models. By implementing more knowledge on the role of miRNAs in the progression towards heart failure, this can potentially be used in the development of miRNA-based therapeutic interventions in the treatment of myocarditis and thereby preventing the progression towards heart failure. The first part of this review will focus on the natural course of myocarditis and the progression towards heart failure. Secondly, we will discuss the current knowledge on alterations of miRNA expression patterns, and suggest some possible future interventions.

Wnt11 gene therapy with adeno-associated virus 9 improves the survival of mice with myocarditis induced by coxsackievirus B3 through the suppression of the inflammatory reaction

The wnt signaling pathway plays important roles in development and in many diseases. Recently several reports suggest that non-canonical Wnt proteins contribute to the inflammatory response in adult animals. However, the effects of Wnt proteins on virus-induced myocarditis have not been explored. Here, we investigated the effect of Wnt11 protein in a model of myocarditis induced by coxsackievirus B3 (CVB3) using recombinant adeno-associated virus 9 (rAAV9). The effect of Wnt11 gene therapy on a CVB3-induced myocarditis model was examined using male BALB/c mice. Mice received a single intravenous injection of either rAAV9-Wnt11 or rAAV9-LacZ 2 weeks before intraperitoneal administration of CVB3. Intravenous injection of the rAAV9 vector resulted in efficient, durable, and relatively cardiac-specific transgene expression. Survival was significantly greater among rAAV9-Wnt11 treated mice than among mice treated with rAAV9-LacZ (87.5% vs. 54.1%, P < 0.05). Wnt11 expression also reduced the infiltration of inflammatory cells, necrosis of the myocardium, and suppressed the mRNA expression of inflammatory cytokines. This is the first report to show that Wnt11 expression improves the survival of mice with CVB3-induced myocarditis. AAV9-mediated Wnt11 gene therapy produces beneficial effects on cardiac function and increases the survival of mice with CVB3-induced myocarditis through the suppression of both infiltration of inflammatory cells and gene expression of inflammatory cytokines.

Remission of CVB3-induced myocarditis with Astragaloside IV treatment requires A20 (TNFAIP3) up-regulation

Viral myocarditis (VMC) most prevalently caused by coxsackievirus B3 (CVB3) infection is characterized by severe cardiac inflammation. Therapeutic options for the disease are still limited. Astragaloside IV (AST-IV), a purified small molecular saponin (C₄₁H₆₈O₁₄, MW 784), is the main active component of Chinese medical herb Astragalus which has been empirically prescribed for the treatment of heart dysfunction for centuries. In this study, we investigated the effect of AST-IV on CVB3-induced myocarditis and explored its possible mechanism involved. The results showed that AST-IV administration alleviated the severity of myocarditis and attenuated cardiac inflammation, which was mediated by inhibition of nuclear factor-kappaB (NF-κB) signalling. Importantly, we further identified that the inhibitory effect of AST-IV on NF-κB signalling was through increasing A20 (TNFAIP3) expression. Moreover, we validated that A20 was critical for the therapeutic efficacy of AST-IV on CVB3-induced myocarditis. Finally, we revealed that AST-IV enhanced A20 expression at post-transcriptional level by stabilization of mRNA. Our findings uncover a previously unknown mechanism for AST-IV in the treatment of VMC because of modulating inflammatory response via increasing A20 expression, which provide a potential target for screening new drugs and are helpful for optimization of the therapeutic strategies for VMC.

Arrhythmias in children with ventricular assist devices

BACKGROUND

Children with decompensated heart failure are at high risk for arrhythmias, and ventricular assist device placement is becoming a more common treatment strategy. The impact of ventricular assist devices on arrhythmias and how arrhythmias affect the clinical course of this population are not well described.

METHODS AND RESULTS

A single-centre retrospective analysis of children receiving a ventricular assist device between 1998 and 2011 was performed. In all, 45 patients received 56 ventricular assist devices. The median age at initial placement was 13 years (interquartile range 6-15). The median duration of support was 10 days (range 2-260). The aetiology of heart failure included cardiomyopathy, transplant rejection, myocarditis, and congenital heart disease. In all, 32 patients (71%) had an arrhythmia; 19 patients (42%) had an arrhythmia before ventricular assist device and eight patients (18%) developed new arrhythmias on ventricular assist device. Ventricular tachycardia was most common (25/32, 78%). There was no correlation between arrhythmia and risk of death or transplantation (p=0.14). Of the 15 patients who weaned from ventricular assist device, post-ventricular assist device arrhythmias occurred in nine (60%), with five (33%) having their first arrhythmia after weaning. Patients with ventricular dysfunction after ventricular assist device were more likely to have arrhythmias (p<0.02).

CONCLUSIONS

Arrhythmias, especially ventricular, are common in children requiring ventricular assist device. They frequently persist for those able to wean from ventricular assist device.

Organ-specific protective role of NKT cells in virus-induced inflammatory demyelination and myocarditis depends on mouse strain

Theiler's murine encephalomyelitis virus (TMEV) can induce demyelination or myocarditis in susceptible mouse strains. A deficiency of NKT cells exacerbated TMEV-induced demyelinating disease (TMEV-IDD) in SJL/J and BALB/c mice. In C57BL/6 background, however, NKT-cell-deficient Jα18 KO mice remained as resistant to TMEV-IDD as wild-type mice. Echocardiography and histology showed that Jα18 KO mice developed more severe myocarditis (greater T cell infiltration and fibrosis) than wild-type mice, suggesting a protective role of NKT cells in myocarditis in C57BL/6 mice. Jα18 KO mice had higher cardiac viral RNA and anti-viral antibody titers, but had lower lymphoproliferation and IL-4 and IL-10 production.

Management of fulminant myocarditis: a diagnosis in search of its etiology but with therapeutic options

Fulminant myocarditis is a clinical syndrome with signs of acute heart failure, cardiogenic shock, or life-threating rhythm disturbances in the context of suspected myocarditis. It is not an etiological diagnosis, but may have different underlying causes and pathogenetic processes - viral, bacterial, toxic, and autoreactive. Clinical management of the disease entity at the acute stage involves hemodynamic monitoring in an intensive care unit or similar setting. Rapid routine work-up is mandatory with serial EKGs, echocardiography, cardiac MRI, heart catheterization with endomyocardial biopsy for histology, immunohistology, and molecular analysis for the underlying infection and pathogenesis. Heart failure therapy is warranted in all cases according to current guidelines. For fulminant autoreactive myocarditis, immunosuppressive treatment is beneficial; for viral myocarditis, IVIg can resolve the inflammation, reduce the viral load, and even eradicate the microbial agent. ECMO, IABP, ventricular assist devices, LifeVest, or ICD implantation can bridge to recovery or to heart transplantation.

Impairment of myocardial mitochondria in viral myocardial disease and its reflective window in peripheral cells

BACKGROUND

Viral myocardial disease (VMD) is a common disease inducing heart failure. It has not been clear the roles of mitochondrial damage in the pathological changes of cardiomyocytes in VMD.

METHODS

Myocardial tissues and lymphocytes were collected from 83 VMD patients. Control groups included 12 cases of healthy accidental death with myocardial autopsy and 23 healthy blood donors. The mouse model of viral myocarditis (VMC) was established by Coxsackie virus B3 infection and myocardial tissues and skeletal muscle were collected. Mitochondrial DNA (mtDNA) deletion rate was quantitatively determined using polymerase chain reaction.

RESULTS

There was significantly difference of myocardial mitochondrial DNA deletion rate between VMD or VMC group and control group (P<0.05). Moreover, the loss of mitochondrial membrane phospholipids was significantly different between VMD or VMC group and control group. In VMC mice, there were negative correlations between myocardial mtDNA3867 deletion rate and left ventricular peak systolic pressure (LVPSP) (r = -0.66, P<0.05), and between myocardial mtDNA3867 deletion rate and +dp/dtmax (r = -0.79, P<0.05), while there was positive correlation between myocardial mtDNA3867 deletion rate and -dp/dtmax (r = 0.80, P<0.05).

CONCLUSION

Mitochondrial damage is an important pathophysiological mechanism leading to myocardial injury and cardiac dysfunction. The mitochondrial damage in the skeletal muscle and lymphocytes reflect a "window" of myocardial mitochondrial damage.

Correlations of the changes in bioptic findings with echocardiographic, clinical and laboratory parameters in patients with inflammatory cardiomyopathy

Patients with myocarditis and left ventricular (LV) dysfunction may improve after standard heart failure therapy. This improvement seems to be related to retreat of myocardial inflammation. The aim of the present study was to assess changes in clinical, echocardiographic and some laboratory parameters and to correlate them with changes in the number of inflammatory infiltrating cells in endomyocardial biopsy (EMB) samples during the 6-month follow-up, and to define predictors of LV function improvement among baseline parameters. Forty patients with biopsy-proven myocarditis and impaired LV function (LV ejection fraction-LVEF <40 %) with heart failure symptoms ≤ 6 months were evaluated. Myocarditis was defined as the presence of >14 mononuclear leukocytes/mm(2) and/or >7 T-lymphocytes/mm(2) in the baseline EMB. The EMB, echocardiography and clinical evaluation were repeated after 6 months of standard heart failure therapy. LVEF improved on average from 25 ± 9 to 42 ± 12 % (p < 0.001); LV end-systolic volume and LV end-diastolic volume (LVEDV) decreased from 158 ± 61 to 111 ± 58 ml and from 211 ± 69 to 178 ± 63 ml (both p < 0.001). NYHA class decreased from 2.6 ± 0.5 to 1.6 ± 0.6 (p < 0.001) and NTproBNP from 2892 ± 3227 to 851 ± 1835 µg/ml (p < 0.001). A decrease in the number of infiltrating leukocytes (CD45+/LCA+) from 23 ± 15 to 13 ± 8 cells/mm(2) and in the number of infiltrating T lymphocytes (CD3+) from 7 ± 5 to 4 ± 3 cells/mm(2) (both p < 0.001) was observed. The decline in the number of infiltrating CD45+ cells significantly correlated with the change in LVEF (R = -0.43; p = 0.006), LVEDV (R = 0.39; p = 0.012), NYHA classification (R = 0.35; p = 0.025), and NTproBNP (R = 0.33; p = 0.045). The decrease in the number of CD3+ cells correlated with the change of systolic and diastolic diameters of the left ventricle (R = -0.33; p = 0.038 and R = -0.45; p = 0.003) and with the change in LVEDV (R = -0.43; p = 0.006). Tricuspid annular plane systolic excursion (TAPSE) (OR 0.61; p = 0.005) and early transmitral diastolic flow velocity (E wave) (OR 0.89; p = 0.002) were identified as predictors of LVEF improvement. Improvements in clinical status, LV function and NTproBNP levels correlated with decrease in the number of infiltrating inflammatory cells. TAPSE and E wave velocity were significant predictors of improvement in multivariate regression. Our observations suggest that contemporary guidelines-based therapy of heart failure is an effective treatment option in patients with recent onset biopsy-proven inflammatory cardiomyopathy.

Roles of PAR1 and PAR2 in viral myocarditis

Viral myocarditis is estimated to cause ~20% of sudden death in people under the age of 40. A variety of viruses have been found to cause myocarditis including coxsackievirus B3 (CVB3). Many studies have been performed with CVB3 because there is a mouse model of CVB3-induced myocarditis. Studies have shown that the TLR3-IFNβ pathway plays a central role in the innate immune response to CVB3 infection. Our laboratory studies the role of protease activated receptors (PAR) in different biological responses including viral infection. We examined the effect of a deficiency in either PAR1 or PAR2 on CVB3-induced myocarditis. Interestingly, we found that PAR1 knockout mice had increased cardiac injury whereas PAR2 knockout mice had decreased cardiac injury. Our studies support the notion that PARs modulate the innate immune response and can have both positive and negative effects on TLR-dependent responses.

Expressions of CD11a, CD11b, and CD11c integrin proteins in rats with myocardial hypertrophy

OBJECTIVES

To examine the expressions of CD11a, CD11b, and CD11c integrins in the myocardial tissues of rats with isoproterenol-induced myocardial hypertrophy. This study also provided morphological data to investigate the signal transduction mechanisms of myocardial hypertrophy and reverse it.

MATERIALS AND METHODS

A myocardial hypertrophy model was established by subcutaneously injecting isoprenaline in healthy adult Sprague-Dawley rats. Myocardial tissues were obtained, embedded in conventional paraffin, sectioned, and stained with hematoxylin. Pathological changes in myocardial tissues were then observed. The expressions and distributions of CD11a, CD11b, and CD11c integrins were detected by immunohistochemistry. Changes in the mRNA expressions of CD11a, CD11b, and CD11c in the myocardial tissues of rats were detected by RT-PCR. Image analysis software was used to determine the expressions of CD11a, CD11b, and CD11c integrins quantitatively.

RESULTS

Immunohistochemical results showed that the positive expressions of CD11a, CD11b, and CD11c integrins increased significantly in the experimental group compared with those in the control group. The mRNA expressions of CD11a, CD11b, and CD11c in the myocardial tissues of rats were consistent with the immunohistochemical results.

CONCLUSION

The increase in the protein expressions of CD11a, CD11b, and CD11c integrins may have an important role in the occurrence and development of myocardial hypertrophy.

Cardiac sarcoidosis: case report, workup, and review of the literature

INTRODUCTION

Cardiovascular disease is the leading cause of death worldwide, with coronary heart disease being the most common manifestation disease. While deaths attributed to coronary heart disease are falling in the developed world, the number of patients with cardiomyopathy continues to increase. In this paper, the current literature on imaging modalities for infiltrative and inflammatory cardiomyopathies is reviewed, focusing on the three most common diagnoses, namely sarcoidosis, amyloidosis, and myocarditis.

CASE REPORT

A 43-year-old male presented with palpitations and left ventricular systolic dysfunction for a second opinion following an initial nondiagnostic workup. The employed clinical and radiologic approach that led to a definitive diagnosis and disease-specific treatment is presented here.

CONCLUSION

The current algorithms and the strengths and weaknesses of the various radiologic techniques in establishing a diagnosis in patients who present with new onset cardiomyopathy are reviewed. Recommendations are provided regarding the selection between echocardiography, computed tomography radionuclide imaging, and magnetic resonance imaging in diagnosing the various causes of cardiomyopathy.

NK-derived IFN-γ/IL-4 triggers the sexually disparate polarization of macrophages in CVB3-induced myocarditis

Coxsackievirus B3 (CVB3) is a common etiology of myocarditis with an increased morbidity and mortality in males. We previously reported that differential polarization of macrophages contributed to sexually dimorphic susceptibility of mice to CVB3-induced myocarditis. However, the underlying kinetics, impetus as well as the molecular mechanism remain unclear. Here, we demonstrated that myocardial macrophages started to polarize at as early as day 5 post CVB3 infection in both genders of BALB/c mice, with M1 phenotype detected in males and M2a phenotype in females, and this trend was further amplified at day 7 when myocarditis reached peak. In addition, we identified that prevailed IFN-γ in males and dominant IL-4 in females were critical myocardial cytokines for the disparate macrophage polarization, which respectively activated JAK1-STAT1 and JAK3-STAT6 pathways. Strikingly, we found that the main source of IFN-γ and IL-4 cytokines in both genders were myocardial infiltrating NK cells, which differentially secreted cytokines in various microenvironments manifested synergistically by sex hormones and CVB3 infection. Consistently, depletion of NK cells significantly impeded the myocardial macrophage polarization in both genders of CVB3-infected mice. Collectively, these data indicated that myocardial NK-derived IFN-γ/IL-4 was critical for the differential polarization of macrophages in CVB3-induced myocarditis via activating JAK1-STAT1 and JAK3-STAT6 pathways respectively. Our study may help understand the mechanism of sexually differential polarization of macrophages and provide clues for the gender bias in CVB3-induced myocarditis.

The role of 1.5 tesla MRI and anesthetic regimen concerning cardiac analysis in mice with cardiomyopathy

Accurate assessment of left ventricular function in rodent models is essential for the evaluation of new therapeutic approaches for cardiac diseases. In our study, we provide new insights regarding the role of a 1.5 Tesla (T) magnetic resonance imaging (MRI) device and different anesthetic regimens on data validity. As dedicated small animal MRI and echocardiographic devices are not broadly available, we evaluated whether monitoring cardiac function in small rodents with a clinical 1.5 T MRI device is feasible. On a clinical electrocardiogram (ECG) synchronized 1.5 T MRI scanner we therefore studied cardiac function parameters of mice with chronic virus-induced cardiomyopathy. Thus, reduced left ventricular ejection fraction (LVEF) could be verified compared to healthy controls. However, our results showed a high variability. First, anesthesia with medetomidine, midazolam and fentanyl (MMF) led to depressed cardiac function parameters and more variability than isoflurane gas inhalation anesthesia, especially at high concentrations. Furthermore, calculation of an average ejection fraction value from sequenced scans significantly reduced the variance of the results. To sum up, we introduce the clinical 1.5 T MRI device as a new tool for effective analysis of left ventricular function in mice with cardiomyopathy. Besides, we suggest isoflurane gas inhalation anesthesia at high concentrations for variance reduction and recommend calculation of an average ejection fraction value from multiple sequenced MRI scans to provide valid data and a solid basis for further clinical testing.

Myocarditis in children

Myocarditis, a masquerader of common illnesses, presents with non-specific symptoms which are often missed by clinicians. The diagnosis is made based on clinical presentation and echocardiography findings and requires a high degree of clinical suspicion. The authors report seven children with myocarditis with review of spectrum of clinical presentation and management.

Multiple roles of the coagulation protease cascade during virus infection

The coagulation cascade is activated during viral infections. This response may be part of the host defense system to limit spread of the pathogen. However, excessive activation of the coagulation cascade can be deleterious. In fact, inhibition of the tissue factor/factor VIIa complex reduced mortality in a monkey model of Ebola hemorrhagic fever. Other studies showed that incorporation of tissue factor into the envelope of herpes simplex virus increases infection of endothelial cells and mice. Furthermore, binding of factor X to adenovirus serotype 5 enhances infection of hepatocytes but also increases the activation of the innate immune response to the virus. Coagulation proteases activate protease-activated receptors (PARs). Interestingly, we and others found that PAR1 and PAR2 modulate the immune response to viral infection. For instance, PAR1 positively regulates TLR3-dependent expression of the antiviral protein interferon β, whereas PAR2 negatively regulates expression during coxsackievirus group B infection. These studies indicate that the coagulation cascade plays multiple roles during viral infections.

In vivo ablation of type I interferon receptor from cardiomyocytes delays coxsackieviral clearance and accelerates myocardial disease

Acute coxsackievirus B3 (CVB3) infection is one of the most prevalent causes of acute myocarditis, a disease that frequently is identified only after the sudden death of apparently healthy individuals. CVB3 infects cardiomyocytes, but the infection is highly focal, even in the absence of a strong adaptive immune response, suggesting that virus spread within the heart may be tightly constrained by the innate immune system. Type I interferons (T1IFNs) are an obvious candidate, and T1IFN receptor (T1IFNR) knockout mice are highly susceptible to CVB3 infection, succumbing within a few days of challenge. Here, we investigated the role of T1IFNs in the heart using a mouse model in which the T1IFNR gene can be ablated in vivo, specifically in cardiomyocytes. We found that T1IFN signaling into cardiomyocytes contributed substantially to the suppression of viral replication and infectious virus yield in the heart; in the absence of such signaling, virus titers were markedly elevated by day 3 postinfection (p.i.) and remained high at day 12 p.i., a time point at which virus was absent from genetically intact littermates, suggesting that the T1IFN-unresponsive cardiomyocytes may act as a safe haven for the virus. Nevertheless, in these mice the myocardial infection remained highly focal, despite the cardiomyocytes' inability to respond to T1IFN, indicating that other factors, as yet unidentified, are sufficient to prevent the more widespread dissemination of the infection throughout the heart. The absence of T1IFN signaling into cardiomyocytes also was accompanied by a profound acceleration and exacerbation of myocarditis and by a significant increase in mortality.

IMPORTANCE

Acute coxsackievirus B3 (CVB3) infection is one of the most common causes of acute myocarditis, a serious and sometimes fatal disease. To optimize treatment, it is vital that we identify the immune factors that limit virus spread in the heart and other organs. Type I interferons play a key role in controlling many virus infections, but it has been suggested that they may not directly impact CVB3 infection within the heart. Here, using a novel line of transgenic mice, we show that these cytokines signal directly into cardiomyocytes, limiting viral replication, myocarditis, and death.

The whole genome sequence of coxsackievirus B3 MKP strain leading to myocarditis and its molecular phylogenetic analysis

BACKGROUND

In recent years, the reported infection cases by coxsackievirus (CV) have been on the rise. In order to reveal the relationship between the nucleotide and amino acid sequences and the viral virulence of the CVB3/MKP strain causing myocarditis, we initially confirmed the virulence of the strain in myocardial tissue and then carried out the whole genome sequencing of CVB3/MKP strain and performed a phylogenetic analysis among different CVB3 strains.

METHODS

CVB3/MKP infected mouse model was established to check lesions of myocardial tissue in mice using immunohistochemical detection at different periods. RT-PCR analysis was used to amplify seven fragments covering the whole viral sequence and comparable analysis was performed.

RESULTS

The immunohistochemical results showed that particles of CVB3/MKP virus persisted in the cardiac tissue and caused severe pathology. The length of whole genome sequence of CVB3/MKP strain was 7400 bp. CVB3/MKP had 99.7% and 99.6% homology in nucleotide sequence with CVB3/28 and non-virulent CVB3/0, respectively. The former can induce pancreatitis and myocarditis. The nucleotide sequence in the 5'untranslated region of CVB3/MKP strain shared 99.6% and 99.5% homology with CVB3/20 and CVB3/Nancy, respectively.

CONCLUSION

We confirmed in our animal experiments that CVB3/MKP had cardiotoxicity. CVB3/MKP, CVB3/28, and CVB3/0 may share evolutionary convergence and the 5'untranslated region (5'UTR) may be associated with virulence phenotype. Our findings will provide a basis for identifying the genomic determinant of viral virulence of CVB3/MKP strain and phylogenetic relationship among different CVB3 strains.

Autoimmunity in viral myocarditis

PURPOSE OF REVIEW

To review how autoimmunity is induced in viral myocarditis.

RECENT FINDINGS

Clinical and experimental myocarditis follows microbial infections, but autoimmunity to cardiac antigens leads to heart failure since infected myocytes are sparse and virus clearance is rapid. In mice, CD4+ T cells specific for cardiac alpha myosin heavy chain (αMYHC) cause myocarditis and mice tolerized to αMYHC are protected from virus challenge proving pathogenesis depends upon autoimmunity. Most importantly, multiple microbes share the same mimicking epitope with αMYHC. Serial infections with very different microbes could result in memory responses to the shared epitope leading to aggressive and severe heart failure. A similar phenomenon may explain autoimmune diseases with suspected infectious causes, where specific pathogens have not been identified. Production of the relevant cardiac epitope for antigen presentation requires more than myosin release from dead myocytes. Otherwise, myocarditis would commonly follow myocardial infarcts. The inherent nature of the innate immune response associated with viral infections in the heart is crucial to cardiac epitope expression.

SUMMARY

Antigenic mimicry between microbes and cardiac proteins causes autoimmunity in myocarditis. Characteristics of innate immunity associated with cardiac infection determine relevant epitope expression (cryptic epitopes).

Role of endomyocardial biopsy for children presenting with acute systolic heart failure

Myocarditis, an inflammatory disease of the heart, frequently results from viral infections, postviral immune-mediated responses, or both. It is a common cause of acute-onset systolic heart failure in children. Endomyocardial biopsy (EMB) remains the gold standard for the diagnosis of myocarditis. However, EMB is not performed for most myocarditis cases involving children in the United States. Clinical scenarios in which EMB results added unique prognostic data and guidance to therapy have been defined recently. This review outlines the role of EMB in the diagnosis and management of myocarditis for children presenting with acute-onset systolic heart failure.

Acute mechanical circulatory support for fulminant myocarditis complicated by cardiogenic shock

In fulminant myocarditis complicated by cardiogenic shock, early mechanical circulatory support (MCS) may prevent cardiomyopathy and death. We sought to examine the outcomes of patients with fulminant myocarditis supported with MCS. A retrospective review of patients with acute cardiogenic shock treated with MCS from 2007 to 2013 was conducted, and patients with a diagnosis of fulminant myocarditis were included in this series. At our center, 260 patients received MCS for acute cardiogenic shock, and 11 were implanted for fulminant myocarditis. Eight received the Centrimag biventricular assist device (BIVAD), and three received veno-arterial extracorporeal membrane oxygenator (VA ECMO), though 1 VA ECMO-supported patient was transitioned to BIVAD due to refractory shock. The mean acute support time was 14.7 ± 4.4 days. Two patients required long-term left ventricular assist devices and were further supported for 55 and 112 days. Eight patients recovered with a mean ejection fraction of 54 ± 7 %, and one was successfully transplanted. Eight patients survived to discharge (73 %) with mean follow-up: 292.6 ± 306.8 days. All three deaths were due to neurologic complications. MCS should be considered in patients with fulminant myocarditis complicated by shock. With aggressive medical therapy, early utilization of MCS carries promising outcomes.