Ongoing Myocarditis Research Articles

Low rates of myocardial fibrosis and ventricular arrhythmias in recreational athletes after SARS-CoV-2 infection.

High rates of cardiac involvement were reported in the beginning of the coronavirus disease 2019 (COVID-19) pandemic. This led to anxiety in the athletic population. The current study was set up to assess the prevalence of myocardial fibrosis and ventricular arrhythmias in recreational athletes with the recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Consecutive adult recreational athletes (≥18 years old, ≥4 h of mixed type or endurance sports/week) underwent systematic cardiac evaluation after a prior confirmed COVID-19 infection. Evaluation included clinical history, electrocardiogram (ECG), 5-day Holter monitoring, and cardiac magnetic resonance (CMR) imaging with simultaneous measurement of high-sensitive cardiac Troponin I. Data from asymptomatic or mildly symptomatic athletes (Group 1) were compared with those with moderate to severe symptoms (Groups 2-3). Furthermore, a comparison with a historical control group of athletes without COVID-19 (Master@Heart) was made. In total, 35 athletes (18 Group 1, 10 female, 36.9 ± 2.2 years, mean 143 ± 20 days following diagnosis) were evaluated. The baseline characteristics for the Group 1 and Groups 2-3 athletes were similar. None of the athletes showed overt myocarditis on CMR based on the updated Lake Louise criteria for diagnosis of myocarditis. The prevalence of non-ischemic late gadolinium enhancement [1 (6%) Group 1 vs. 2 (12%) Groups 2-3; p = 0.603] or ventricular arrhythmias [1 Group 1 athlete showed non-sustained ventricular tachycardia (vs. 0 in Groups 2-3: p = 1.000)] were not statistically different between the groups. When the male athletes were compared with the Master@Heart athletes, again no differences regarding these criteria were found. In our series of recreational athletes with prior confirmed COVID-19, we found no evidence of ongoing myocarditis, and no more detection of fibrosis or ventricular arrhythmias than in a comparable athletic pre-COVID cohort. This points to a much lower cardiac involvement of COVID-19 in athletes than originally suggested.

Cardiac magnetic field map topology quantified by Kullback-Leibler entropy identifies patients with clinically suspected myocarditis.

Myocarditis is a condition that can have severe adverse outcomes and lead to sudden cardiac death if remaining undetected. This study tested the capability of cardiac magnetic field mapping to detect patients with clinically suspected myocarditis. This could open up the way for rapid, non-invasive, and cost-effective screening of suspected cases before a gold standard assessment via endomyocardial biopsy. Historical cardiac magnetic field maps (n = 97) and data from a state-of-the-art magnetocardiography device (n = 30) were analyzed using the Kullback-Leibler entropy (KLE) for dimensionality reduction and topological quantification. Linear discriminant analysis was used to discern between patients with ongoing myocarditis and healthy controls. The STT segment of a magnetocardiogram, i.e., the section between the end of the S wave and the end of the T wave, was best suited to discern both groups. Using a 250-ms excerpt from the onset of the STT segment gave a reliable classification between the myocarditis and control group for both historic data (sensitivity: 0.83, specificity: 0.85, accuracy: 0.84) and recent data (sensitivity: 0.69, specificity: 0.88, accuracy: 0.80) using the KLE to quantify the topology of the cardiac magnetic field map. The implementation based on KLE can reliably distinguish between clinically suspected myocarditis patients and healthy controls. We implemented an automatized feature selection based on LDA to replace the observer-dependent manual thresholding in previous studies.

Assessment of cardiac involvement in patients recovered from corona virus disease-19 (COVID-19) infection using magnetic resonance imaging

Abstract Background Cardiac sequelae after recovery from COVID-19 infection has not been well-established. Recent studies have used cardiac magnetic resonance (CMR) imaging to assess myocardial involvement or ongoing myocarditis in patients with prior COVID-19 infection. Objectives The primary objective of this study was to identify the CMR imaging findings in adult COVID-19 recovered patients. Methods This was a single-center retrospective observational cohort study of adult COVID-19 recovered patients who underwent cardiac magnetic resonance imaging. Patient demographics, CMR findings, blood marker results, and treatment received were obtained. Results Of the 77 included patients, 42 (54.55%) were male, and the median age was 45 years. Only 6 patients had completely normal scans, making the prevalence of an abnormal CMR 92.21% (95% CI 83.5%–96.5%). All those with an abnormality demonstrated late gadolinium enhancement (LGE), and of these, 64 (90%) had preserved left ventricular ejection fraction (LVEF). Thirty-four patients (44%) had evidence of myocardial edema. Among patients with myocardial edema and LGE, the median numbers of involved segments were 4 (range 1–16) and 7 (range 1–15), respectively. Myocardial edema was most frequently found in the mid inferolateral segment (53%), followed by the basal inferior septum, basal anterior septum, and basal inferolateral segments (each with 41%). Meanwhile, late gadolinium enhancements were most commonly located in the basal inferior septum (75%), mid inferior septum (80%), and basal anterior septum (73%). Conclusion Cardiac involvement, particularly edema and late gadolinium enhancement, affecting multiple myocardial segments were observed in a considerable number of patients recovered from COVID-19. Funding Acknowledgement Type of funding sources: None.

COVID-19-Vaccination-Induced Myocarditis in Teenagers: Case Series with Further Follow-Up.

Presently, the whole globe is struggling the tough challenge of the COVID-19 pandemic. Vaccination remains the most effective and safe COVID-19 weapon for adults and in the paediatric population. Aside from possible mild and moderate post-vaccination side effects, more severe side effects may occur. We retrospectively analysed a group of 5 teenagers aged from 15 to 17 years with obesity/overweight (BMI ranging from 24.8 to 30) who presented typical myocarditis symptoms following the first or second dose (3 and 2 patients, respectively) of the COVID-19 vaccine. In the whole study group, a significant increase in troponin serum concentration was observed (1674–37,279.6 ng/L) with a further quick reduction within 3–4 days. In all patients, ST segments elevation or depression with repolarisation time abnormalities in electrocardiography were noticed. Chest X-ray results were within normal limits. Echocardiography showed normal left ventricular diameter (47–56.2 mm) with ejection fraction between 61–72%. All patients were diagnosed with myocarditis based on cardiac magnetic resonance (CMR) imaging. During further hospitalisation, swift clinical improvement was notable. Follow-up in the whole study group was obtained after 106–134 days from initial CMR, revealing no myocarditis symptoms, proper troponin level, and no ECG or echocardiographic abnormalities. At the same time, persistent myocardium injury features were detected in the whole study group, including ongoing myocarditis. COVID-19-vaccine-induced myocarditis seems to be a mild disease with fast clinical recovery, but the complete resolution of the inflammatory process may last over 3 months. Further follow-up and investigation for assessing subsequent implications and long-term COVID-19-vaccine-induced myocarditis is required.

Non-pulmonary manifestations of coronavirus disease 2019 (COVID-19): case report

: Doctors from various specialties across the world are faced with the management of coronavirus disease 2019 (COVID-19). The typical presentation is one of viral pneumonia, with a large spectrum of disease severity. Increasingly, extra-pulmonary manifestations are being reported, often in those with significant pulmonary pathology. Here we discuss a novel presentation of COVID-19, with no pulmonary involvement and the challenges faced by clinicians in achieving the correct diagnosis. A previously fit and well 30-year-old female presented with gastroenteritis, pyrexias, myalgia, rashes, conjunctivitis, and myocarditis. There were no respiratory features, either from her history or clinical examination. Initial and subsequent reverse transcription polymerase chain reaction (RT-PCR) swabs were negative for severe acute respiratory failure coronavirus 2 (SARS-CoV-2), alongside normal appearances of her lungs on computed tomography scans. Her third and final COVID-19 RT-PCR swab was positive, just prior to transfer for her ongoing myocarditis management, at a specialist cardiac critical care. She went on to make a full recovery. Novel presentations of COVID-19 signify a new challenge to clinicians. Correct diagnosis is important for the patient, as well as staff safety. Atypical presentations often have non-specific clinical features, and so a strong index of suspicion, appropriate exclusion of differentials and a multi-disciplinary approach are needed.

High Prevalence of Pericardial Involvement in College Student Athletes Recovering From COVID-19

ObjectivesThis study sought to explore the spectrum of cardiac abnormalities in student athletes who returned to university campus in July 2020 with uncomplicated coronavirus disease 2019 (COVID-19). BackgroundThere is limited information on cardiovascular involvement in young individuals with mild or asymptomatic COVID-19. MethodsScreening echocardiograms were performed in 54 consecutive student athletes (mean age 19 years; 85% male) who had positive results of reverse transcription polymerase chain reaction nasal swab testing of the upper respiratory tract or immunoglobulin G antibodies against severe acute respiratory syndrome coronavirus type 2. Sequential cardiac magnetic resonance imaging was performed in 48 (89%) subjects. ResultsA total of 16 (30%) athletes were asymptomatic, whereas 36 (66%) and 2 (4%) athletes reported mild and moderate COVID-19 related symptoms, respectively. For the 48 athletes completing both imaging studies, abnormal findings were identified in 27 (56.3%) individuals. This included 19 (39.5%) athletes with pericardial late enhancements with associated pericardial effusion. Of the individuals with pericardial enhancements, 6 (12.5%) had reduced global longitudinal strain and/or an increased native T1. One patient showed myocardial enhancement, and reduced left ventricular ejection fraction or reduced global longitudinal strain with or without increased native T1 values was also identified in an additional 7 (14.6%) individuals. Native T2 findings were normal in all subjects, and no specific imaging features of myocardial inflammation were identified. Hierarchical clustering of left ventricular regional strain identified 3 unique myopericardial phenotypes that showed significant association with the cardiac magnetic resonance findings (p = 0.03). ConclusionsMore than 1 in 3 previously healthy college athletes recovering from COVID-19 infection showed imaging features of a resolving pericardial inflammation. Although subtle changes in myocardial structure and function were identified, no athlete showed specific imaging features to suggest an ongoing myocarditis. Further studies are needed to understand the clinical implications and long-term evolution of these abnormalities in uncomplicated COVID-19.

Focal Myocarditis in Professonal Female Athlete: A Case Report

Abstract A 35-year-old female athlete appealed to her sports physician on new onset of frequent palpitations, just before an important competition. Initial electrocardiography revealed unifocal premature ventricular complexes in the form of bigeminy. Echocardiography revealed fine-granulated hyperdensic changes in septum. Global strain rate was within a range normal, as well as pulsed tissue Doppler ultrasound. Patient was referred for cardiac MRI, which revealed interventricular septum with rougher compounds, but with preserved continuity, with thickness of 10 mm, which is in the middle of the LV, in length of 5 mm, thinned to a thickness of 4 mm. ELISA laboratory test demonstrated an increased titer of IgM antibodies for adenovirus. Six months later, the patient was referred for control MRI of the heart, which showed pronounced trabeculation of infero-lateral wall of the left ventricle, but without certain criteria for non-compaction cardiomyopathy. There was T1 oedema component in apical septal segment and apical segment of the left ventricle. There was increase of the signal in late gadolinium enhancement in the medial parts of the same segments but also in the segment of the basomedial septum, with previous focal myocarditis. These findings suggest myocardial fibrosis in the segments that were stricken by myocarditis, now without active ongoing myocarditis, but without consequent myocardial fibrosis.

End-Stage Biventricular Failure from Necrotizing Autoimmune Myopathy

Necrotizing autoimmune myopathy is a rare neuromuscular disorder characterized clinically by severe proximal limb muscle weakness and pathologically by necrotic muscle fibers with minimal inflammation. It is often associated with statin therapy, connective tissue diseases, and malignancy. Most have characteristic autoantibodies although a small subset present without myositis-specific autoantibodies. While cardiac involvement is rare, conduction abnormalities, diastolic dysfunction, and wall motion abnormalities have been reported. Severe cardiomyopathy from necrotizing autoimmune myopathy resulting in end-stage biventricular failure is extremely rare without a clear role for guideline-directed medical therapy. A 45-year-old man with hypothyroidism was admitted with several months of worsening proximal muscular weakness. He was found to have new severe biventricular dysfunction with conduction abnormalities during diagnostic work-up. Physical exam was notable for symmetric proximal muscle weakness in upper and lower extremities, sclerodactyly, elevated jugular venous distension, and lower extremity edema. Laboratory testing showed a creatine kinase of 3101 U/L, ANA 1:640, positive RNP antibodies, positive PM/Scl 100 antibodies. Anti-HMGCR antibodies and anti-SRP antibodies were negative. Lower extremity MRI showed diffuse bilateral symmetric myositis around the pelvis consistent with an inflammatory myopathy. EMG suggested irritable myopathy. Left thigh skeletal muscle biopsy showed necrotizing autoimmune myopathy with a paucity of inflammatory cells. Electrocardiogram revealed a right bundle branch block and 1st degree AV block. Frequent atrial and ventricular ectopic beats were seen on telemetry. Transthoracic echocardiogram showed biventricular failure with LVEF 23% and severe global hypokinesis. Cardiac MRI showed patchy foci of delayed subendocardial delayed enhancement. Endomyocardial biopsy did not reveal evidence of lymphocytic infiltration or ongoing myocarditis. Right heart catheterization was notable for elevated biventricular pressures with a cardiac index of 2.18. No obstructive coronary artery disease was seen on coronary angiogram. He was treated with intravenous immunoglobulins, methotrexate, and high-dose prednisone with improvement in proximal weakness. Low-dose spironolactone and lisinopril were started but could not be increased due to degree of hypotension. This case highlights a rare manifestation of an exceedingly rare autoimmune condition associated with high mortality. Given the variability of cardiac involvement in the disorder, a high clinical suspicion is needed to establish an early diagnosis and pursue aggressive treatment with up-front combination immunomodulating therapy, which has been associated with improved outcomes.

Cardiac Magnetic Resonance of Acute Myocarditis in an Human Immunodeficiency Virus Patient Presenting With Acute Chest Pain Syndrome

A 34-year-old woman of Afro Caribbean origin presented to the HIV clinic with a few days’ history of chest pain, chills, and malaise. The chest pain was intermittent, severe, central, radiating to the left arm, worse on lying down, and better on sitting forward. This was preceded by an episode of collapse after palpitations a week earlier. On examination, she had a regular pulse of 84 bpm, blood pressure of 131/71 mm Hg, respiratory rate of 20, temperature of 38°C, and oxygen saturation of 99% on air. Cardiovascular, respiratory, abdominal, and neurological examinations were normal. ECG demonstrated anterolateral ischemic changes (Figure 1). Chest radiograph was normal. Figure 1. ECG showing anterolateral ischemic changes. Biochemical profile was as follows: C-reactive protein, 296 mg/dL; troponin, 3.8 ng/mL; CD4 count, 459; viral load, <50; and hemoglobin, 9.1 g/dL. Her antistreptolysin O titer was 1 in 40, and no antistreptolysin antibodies were detected. Viral titers were negative for cytomegalovirus, adenovirus, Coxiella burnetii , chlamydia (group) and Mycoplasma pneumoniae , enterovirus (including echoviruses, coxsackie …

Persistence of virus and viral genome in myocardium after coxsackievirus B3-induced murine myocarditis.

Following infection with Coxsackievirus B3 (CVB3), A-strain mice develop ongoing myocarditis that persists after the virus ceases to be cultivatable from heart tissue. We studied the natural history of this virus-induced but apparently autoimmune inflammation by means of in situ hybridization (ISH) and by polymerase chain reaction (PCR). Both ISH and culture allowed detection of virus up to 2 weeks post-infection in virtually all heart tissues. In contrast, PCR revealed the presence of viral genome for a substantially longer period of time, i.e. at least 34 days after CVB3 infection. Similarly, the majority of mice showed myocardial inflammation at this time point. However, the persistence of virus did not correlate with ongoing myocarditis, and vice versa. Most mice with ongoing myocarditis produced heart myosin autoantibodies, most probably as a result of tissue damage. The lack of correlation between presence of ongoing inflammation and persistence of virus supports our previous view that the late phase of CVB3-induced myocarditis is mediated by autoimmunological mechanisms.

The viral genetic background determines the outcome of coxsackievirus B3 infection in outbred NMRI mice

The reasons for the different outcome of coxsackievirus B3 (CVB3)-induced heart disease in humans are not well understood. Since there are no experimental data on the course of disease after infection with genetically different CVB3 in a natural variable population until now, we studied the outcome of virus infection in outbred NMRI mice after inoculation of genetically different CVB3 variants. Adult male mice were inoculated with seven closely related CVB3 variants. The histopathological changes of heart and pancreas tissue, antibody induction, virus titers, and persistence of viral positive- as well as negative-strand RNA in spleen and heart tissue were compared at day 7 or day 28 after infection to detect prerequisites and predictive factors for chronic myocarditis. Six CVB3 variants infected NMRI mice. CVB3 infection (i) did not induce detectable myocardial injury, (ii) caused signs of healing up acute myocarditis or (iii) ongoing chronic myocarditis. Neither IgG antibody responses nor the extent of destruction of exocrine pancreatic tissue or viral RNA load in spleen did correlate with myocardial histopathology. In contrast, a high persistent viral RNA load in heart tissue specimens was characteristic for mice developing chronic myocarditis. The results of the present study corroborate high viral load in the acute stage of myocarditis and high amounts of persisting CVB3 RNA in heart tissue as predictive marker of chronic myocarditis. The outcome of CVB3-induced heart disease in outbred NMRI mice depends strongly on the viral genetic background. In particular an important role of viral capsid proteins is suggested.

Sustained Nitric Oxide Synthesis Contributes to Immunopathology in Ongoing Myocarditis Attributable to Interleukin-10 Disorders

Ongoing coxsackievirus B3 (CVB3) myocarditis is characterized by persistence of viral RNA and chronic inflammation primarily mediated by macrophages and T cells. Activated macrophages produce anti-viral effector molecules comprising reactive nitrogen intermediates; however, reactive nitrogen intermediates also contribute to host tissue damage. Controlled activation of macrophages depends on interferon (IFN)-gamma and interleukin (IL)-10. To evaluate mechanisms involved in CVB3-induced pathogenesis of myocarditis, we determined the relationship of inducible nitric-oxide synthase (iNOS) mRNA expression with IFN-gamma and IL-10 secretion during CVB3 infection in different mouse strains. We found in susceptible A.BY/SnJ mice that develop ongoing myocarditis, a low and delayed IFN-gamma secretion and highly diminished IL-10 production compared with resistant C57BL/6 mice. Consequently, iNOS mRNA synthesis was delayed but clearly prolonged in susceptible mice. IL-10 gene-deficient mice confirmed the regulatory role of IL-10 in the outcome of CVB3 myocarditis. These mice did not establish a persistent cardiac infection and revealed IFN-gamma secretion kinetics similar to resistant mice but showed a slightly elongated cardiac iNOS mRNA expression resulting in extended myocarditis. We conclude that coordinated secretion of IFN-gamma and IL-10 is crucial for the effective resolution of CVB3 myocarditis. Moreover, lack of regulatory IL-10 leads to uncontrolled iNOS mRNA production, thus contributing to ongoing myocardial injury.

Ongoing Coxsackievirus Myocarditis Is Associated with Increased Formation and Activity of Myocardial Immunoproteasomes

A growing body of evidence indicates that viral infections of the heart contribute to ongoing myocarditis and dilated cardiomyopathy. Murine models of coxsackievirus B3 (CVB3)-induced myocarditis mimic the human disease and allow identification of susceptibility factors that modulate the course of viral myocarditis. Susceptible mouse strains develop chronic myocarditis on the basis of restricted viral replication, whereas resistant strains recover after successful virus elimination. In comparative whole-genome microarray analyses of infected hearts, several genes involved in the processing and presentation of viral epitopes were found to be uniformly up-regulated in acutely CVB3-infected susceptible mice compared with resistant animals. In particular, expression of the catalytic subunits LMP2, LMP7, and MECL-1, immunoproteasome proteins important in the generation of major histocom-patibility complex (MHC) class I-restricted peptides, was clearly enhanced in the susceptible host. Increased expression resulted in enhanced formation of immunoproteasomes and altered proteolytic activities of proteasomes in the heart. This was accompanied by a concerted up-regulation of the antigen-presenting machinery in susceptible mice. Thus, we propose that increased formation of immunoproteasomes in susceptible mice affects the generation of antigenic peptides and the subsequent T-cell-mediated immune responses.

Canine parvoviral myocarditis

A 5-week-old crossbred pigdog pup was presented in respiratory distress. It appeared to dry retch, and then died suddenly before a clinical examination was performed; a littermate had died suddenly the week before. Histopathological examination revealed an ongoing lymphocytic myocarditis, characterised by myofibril degeneration and lymphocytic inflammatory infiltrates. In scattered degenerate myofibres, there were large amphophilic intranuclear inclusion bodies distending their nuclei. There was also marked pulmonary oedema. Canine parvoviral myocarditis, due to canine parvovirus type 2, was diagnosed. Further questioning regarding the history of this pup revealed that it had been born to an unvac-cinated dam that had been moved late in her pregnancy from an isolated farm on to another property. It seems likely that the dam was naïve and only became exposed to the virus immediately prior to whelping. The lack of wildlife vectors and a well-controlled population of dogs in rural New Zealand means that there may be isolated areas of the country where dogs can reach maturity without becoming exposed to parvovirus, creating the potential for development of this now uncommon syndrome. When parvovirus first arose in New Zealand, between 1979–;1981, parvoviral myocarditis was relatively common, occurring in neonates when the virus was introduced to breeding kennels that previously had been unexposed.

Intranasal delivery of chitosan–DNA vaccine generates mucosal SIgA and anti-CVB3 protection

Coxsackievirus B3 infections are common causes of acute and chronic myocarditis with no effective prophylactic treatment available. We describe here a prophylactic strategy using chitosan–DNA intranasal immunization to induce CVB3 specific immune responses. Intranasal administration with chitosan–DNA complex prepared by votexing DNA with chitosan, a natural mucus absorption enhancer, resulted in transgenic DNA expression in mouse nasopharynx. Mice immunized with chitosan–DNA (pcDNA3-VP1) encoding VP1, major structural protein of CVB3, produced much higher levels of serum IgG and mucosal secretory IgA compared to mice treated with pcDNA3-VP1 or pcDNA3. Increased virus-specific cytotoxic activity of spleen cells derived from chitosan–DNA vaccinated mice was also determined. Chitosan-pcDNA3-VP1 intranasal immunization resulted in 42.9% protection of mice against lethal CVB3 challenge and a significant reduction of viral load after acute CVB3 infection. Meanwhile no myonecrosis or infiltrating immune cells indicating ongoing myocarditis was detected in hearts of surviving mice treated with chitosan–DNA. Together, Our data show that intranasal delivery of chitosan–DNA vaccine successfully induced mucosal SIgA secretion and might be a promising vaccine candidate to protect against CVB3 infection.

Adenovirus-mediated gene transfer of ICOSIg fusion protein ameliorates ongoing experimental autoimmune myocarditis.

Experimental autoimmune myocarditis (EAM) has been used as a model for human myocarditis. We previously demonstrated that blockade of B7/CD28 or CD40/CD40 ligand (CD40L) had a potential preventive effect on EAM, but less therapeutic effect on ongoing EAM. Thus, we searched for the involvement of other costimulatory molecules in EAM. We demonstrated the expression of inducible costimulator (ICOS)/ICOSL molecules in the lymph nodes, spleen, and heart in the EAM rat. We constructed adenovirus vectors containing ICOSIg (Adex1CAICOSIg) to achieve effective inhibition of ICOS/ICOSL interaction, and examined the effects of Adex1CAICOSIg on EAM. Adex1CAICOSIg treatment shortly after the immunization did not inhibit the onset and severity of EAM compared to control rats. On the other hand, delayed treatment with Adex1CAICOSIg significantly inhibited ongoing EAM. The survival rate in rats treated with Adex1CAICOSIg was significantly higher than that of the control group. Furthermore, the affected area ratio of the Adex1CAICOSIg treatment group was significantly lower than that of the control group. This study indicates that ICOS/ICOSL costimulation makes an important contribution to the progression of EAM and that the blockade of this pathway by gene transfer has therapeutic potential for ongoing autoimmune myocarditis.

Characterization of T cell receptor beta chains of accumulating T cells in chronic ongoing myocarditis demonstrated by heterotopic cardiac transplantation in mice.

Autoimmne mechanisms have been implicated in the pathogenesis of chronic ongoing mycarditis. An earlier study of murine chronic ongoing myocarditis reported that infiltrating T cells and macrophages were prominent in the normal donor heart, in a heterotopic cardiac transplantation model. It was demonstrated that myocarditis was transferred to a normal heart transplanted into a mouse with chronic myocarditis. The present study investigated an autoimmune link to the pathogenesis of chronic ongoing myocarditis by analyzing the T cell clonalities in the model. To characterize the accumulating T cells in the donor heart, the T cell receptor beta genes (TCRBG) were amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) from mRNA in the donor hearts and accumulating TCRBG clonotypes were contrasted with those from recipient hearts. Inbred 3-week-old A/J mice were inoculated intraperitoneally with Coxsackievirus B3 (Nancy strain), 2 x 10(4) PFU, and housed for more than 60 days. Normal A/J mouse hearts were transplanted into the same strain of mice without myocarditis, as well as into the mice with chronic ongoing myocarditis. Both recipient and donor hearts were evaluated histologically 2 weeks after the transplantation. TCRBG were amplified by RT-PCR from mRNA of recipient and donor hearts and spleens. The specific accumulating TCRBG clonotypes were identified by their single strand conformation polymorphism. Multiple clonotypic accumulations occurred in the donor heart after cardiac transplantation. Distinct oligoclonal accumulation of TCR Vbeta1, 10, and 13 T cells was found in both recipient and donor hearts in 3 of 4 mice. Moreover, these clonotypes were not observed in spleen cells of the recipient mice. T specific cells expanding clonotypes of TCRBG are responsible for transferring myocarditis to the donor heart. An autoimmune response may, therefore, play a key role in the progression of chronic ongoing myocarditis.

Characterization of T cell receptor β chains of accumulating T cells in chronic ongoing myocarditis demonstrated by heterotopic cardiac transplantation in mice

Characterization of T cell receptor β chains of accumulating T cells in chronic ongoing myocarditis demonstrated by heterotopic cardiac transplantation in mice

Expression of tumour necrosis factor (TNF) receptor/ligand superfamily co-stimulatory molecules CD40, CD30L, CD27L, and OX40L in murine hearts with chronic ongoing myocarditis caused by coxsackie virus B3.

T-cell-mediated myocardial damage has been shown to be involved in acute myocarditis and dilated cardiomyopathy. It is necessary for T-cells to receive a co-stimulatory signal as well as the main signal through the T-cell receptor for antigen-specific T-cell activation to occur. To investigate the roles of the co-stimulatory molecules CD40/CD40L, CD30/CD30L, CD27/CD27L, and OX40/OX40L, which belong to the tumour necrosis factor (TNF) receptor/ligand superfamily, in the development of chronic ongoing myocarditis, the expression of CD40, CD30L, CD27L, and OX40L was analysed in the hearts of A/J mice with myocarditis induced by Coxsackie virus B3 (CVB3). The expression of CD40L, CD30, CD27, and OX40 was also examined on the infiltrating cells. Furthermore, the induction of CD40, CD30L, CD27L, and OX40L was evaluated on cultured cardiac myocytes treated with interferon (IFN)-gamma. CVB3-induced myocarditis resulted in the induction of CD40 and CD30L on the surface of cardiac myocytes. Induction of CD40 and CD30L on cardiac myocytes was confirmed by treatment with IFN-gamma in vitro. CD27L and OX40L were expressed on cardiac myocytes in vivo and in vitro. The expression of CD27L and OX40L on cardiac myocytes was increased, at least partly, by CVB3-induced myocarditis in vivo. Many infiltrating cells expressed CD27 and OX40, whereas much smaller numbers expressed CD40L and CD30. The induction of these molecules, especially CD40 and CD30L, on cardiac myocytes strongly suggests that cardiac myocytes may co-stimulate T-cells and induce cytokine production by T-cells and humoral immune responses. This may play an important role in the pathogenesis of the resulting myocardial damage.

Effects of in vivo administration of anti-B7-1/B7-2 monoclonal antibodies on the survival of mice with chronic ongoing myocarditis caused by Coxsackievirus B3.

In acute myocarditis and dilated cardiomyopathy, it has previously been reported that antigen-specific T-cells infiltrate the heart and play an important role in the myocardial damage involved. For antigen-specific T-cell activation to occur, it is necessary for the T-cell to receive co-stimulatory signals provided by co-stimulatory molecules expressed on the antigen-presenting cell (APC), as well as the main signal provided by binding of the T-cell receptor (TCR) to the antigen. To investigate the roles for the co-stimulatory molecules B7-1 and B7-2 in the development of chronic ongoing viral myocarditis, firstly the expression of B7-1/B7-2 was analysed in the hearts of A/J mice with myocarditis induced by Coxsackievirus B3 (CVB3). Secondly the induction of B7-1/B7-2 on cultured cardiac myocytes treated with interferon (IFN)-gamma was evaluated. Thirdly the effects of the in vivo administration of anti-B7-1/B7-2 monoclonal antibodies (MAbs) on the survival of mice with viral myocarditis were examined. CVB3-induced myocarditis resulted in enhanced expression of B7-1/B7-2 on cardiac myocytes. The expression of B7-1/B7-2 on cardiac myocytes could be induced by IFN-gamma in vitro. In vivo anti-B7-1 MAb treatment significantly prolonged the survival of mice with myocarditis, whereas anti-B7-2 MAb treatment abrogated the protective effect of anti-B7-1. These findings indicate that distinct roles for B7-1 and B7-2 antigens are involved in the development of viral myocarditis and raise the possibility of immunotherapy with anti-B7-1 MAb to prevent T-cell-mediated cardiac myocyte injury and to improve the prognosis of viral myocarditis.