MicroRNA-30a-5p silencing polarizes macrophages toward M2 phenotype to alleviate cardiac injury following viral myocarditis by targeting SOCS1

Viral myocarditis (VMC) is a life-threatening disease characterized by severe cardiac inflammation generally caused by coxsackievirus B3 (CVB3) infection. Several microRNAs (miRNAs or miRs) are known to play crucial roles in the pathogenesis of VMC. The study aimed to decipher the role of miR-30a-5p in the underlying mechanisms of VMC pathogenesis. We first quantified miR-30a-5p expression in a CVB3-induced mouse VMC model. The physiological characteristics of mouse cardiac tissues were then detected by hematoxylin and eosin (HE) and Picrosirius red staining. We established the correlation between miR-30a-5p and SOCS1, using dual-luciferase gene assay and Pearson's correlation coefficient. The expression of inflammatory factors (IFN-γ, IL-6, IL-10, and IL-13), M1 polarization markers [TNF-α, inducible nitric oxide synthase (iNOS)], M2 polarization markers (Arg-1, IL-10), and myocardial hypertrophy markers [atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP)] was detected by RT-qPCR and Western blot analysis. miR-30a-5p was found to be highly expressed in VMC mice. Silencing of miR-30a-5p improved the cardiac function index and reduced heart weight-to-body weight ratio, myocardial tissue pathological changes and fibrosis degree, serological indexes, as well as proinflammatory factor levels, while enhancing anti-inflammatory factor levels in VMC mice. Furthermore, silencing of miR-30a-5p inhibited M1 polarization of macrophages while promoting M2 polarization in vivo and in vitro. SOCS1 was a target gene of miR-30a-5p, and the aforementioned cardioprotective effects of miR-30a-5p silencing were reversed upon silencing of SOCS1. Overall, this study shows that silencing of miR-30a-5p may promote M2 polarization of macrophages and improve cardiac injury following VMC via SOCS1 upregulation, constituting a potential therapeutic target for VMC treatment.NEW & NOTEWORTHY We found in this study that microRNA (miR)-30a-5p inhibition might improve cardiac injury following viral myocarditis (VMC) by accelerating M2 polarization of macrophages via SOCS1 upregulation. Furthermore, the anti-inflammatory mechanisms of miR-30a-5p inhibition may contribute to the development of new therapeutic strategies for VMC.

Acute viral myopericarditis presenting as a transient effusive-constrictive pericarditis caused by coinfection with coxsackieviruses A4 and B3

Acute myopericarditis is usually caused by viral infections, and the most common cause of viral myopericarditis is coxsackieviruses. Diagnosis of myopericarditis is made based on clinical manifestations of myocardial (such as myocardial dysfunction and elevated serum cardiac enzyme levels) and pericardial (such as inflammatory pericardial effusion) involvement. Although endomyocardial biopsy is the gold standard for the confirmation of viral infection, serologic tests can be helpful. Conservative management is the mainstay of treatment in acute myopericarditis. We report here a case of a 24-year-old man with acute myopericarditis who presented with transient effusive-constrictive pericarditis. Echocardiography showed transient pericardial effusion with constrictive physiology and global regional wall motion abnormalities of the left ventricle. The patient also had an elevated serum troponin I level. A computed tomogram of the chest showed pericardial and pleural effusion, which resolved after 2 weeks of supportive treatment. Serologic testing revealed coxsackievirus A4 and B3 coinfection. The patient received conservative medical treatment, including nonsteroidal anti-inflammatory drugs, and he recovered completely with no complications.

Pharmacological and biological antiviral therapeutics for cardiac coxsackievirus infections

Subtype B coxsackieviruses (CVB) represent the most commonly identified infectious agents associated with acute and chronic myocarditis, with CVB3 being the most common variant. Damage to the heart is induced both directly by virally mediated cell destruction and indirectly due to the immune and autoimmune processes reacting to virus infection. This review addresses antiviral therapeutics for cardiac coxsackievirus infections discovered over the last 25 years. One group represents pharmacologically active low molecular weight substances that inhibit virus uptake by binding to the virus capsid (e.g., pleconaril) or inactivate viral proteins (e.g., NO-metoprolol and ribavirin) or inhibit cellular proteins which are essential for viral replication (e.g., ubiquitination inhibitors). A second important group of substances are interferons. They have antiviral but also immunomodulating activities. The third and most recently discovered group includes biological and cellular therapeutics. Soluble receptor analogues (e.g., sCAR-Fc) bind to the virus capsid and block virus uptake. Small interfering RNAs, short hairpin RNAs and antisense oligonucleotides bind to and led to degradation of the viral RNA genome or cellular RNAs, thereby preventing their translation and viral replication. Most recently mesenchymal stem cell transplantation has been shown to possess antiviral activity in CVB3 infections. Taken together, a number of antiviral therapeutics has been developed for the treatment of myocardial CVB infection in recent years. In addition to low molecular weight inhibitors, biological therapeutics have become promising anti-viral agents.

Notes from the field: acute hemorrhagic conjunctivitis outbreaks caused by coxsackievirus A24v --- Uganda and southern Sudan, 2010

CDC was contacted on June 22, 2010, by the Ugandan Ministry of Health (MoH)/Uganda Virus Research Institute and on July 11 by the Government of Southern Sudan (GOSS) via the CDC Global Disease Detection Regional Center in Kenya to perform diagnostic laboratory testing on conjunctival swabs from persons with "red eye syndrome." Widespread, ongoing outbreaks of acute hemorrhagic conjunctivitis (AHC) have been observed in Uganda and Southern Sudan since spring 2010. AHC becomes a reportable condition in outbreak settings. Case numbers were estimated in Uganda after MoH confirmation of reported cases from district health facilities and, in Southern Sudan, after a medical record review in six health facilities. To date, 6,818 cases from 26 districts in Uganda, and 428 cases in Juba, Southern Sudan, have been counted; however, because most cases are not reported, these totals are considered underestimates.

[Intracellular clearance of Coxsakievirus B3 infection by short interfering RNA and its mechanism study]

OBJECTIVE

To evaluate the possibility of short interfering RNA (siRNA) inhibiting Coxsackievirus B3 (CVB3) infection in vitro, and discover the mechanism initially.

METHODS

We obtained proper effective dosage of siRNA by observing cytopathic effect (CPE). Estimate its antiviral activities and its pathway of siRNA by Western Blot assay and RT-PCR.

RESULTS

Results showed that siRNA-3753 can be effectively transfected into HeLa cells, we can achieve a high transfection efficiency up to 98.77% and its effect can last for 48 h stably in cells. 0.6 micromol/L siRNA-3753 got a high inhibiting effect of virus and didn't show any toxicity to cells. So we consider this concentration as the experimental concentration. siRNA-3753 can debase virus reproduction. The antiviral effect is sequence-specific and is not attributable to either interferon or the interferon response effectors protein kinase R (PKR).

CONCLUSION

The data confirmed that siRNA can effectively inhibit CVB3 infection in vitro, its antivirus effect was gained from specific debase of virus genome.

The impact of CVB3 infection on host cell biology

CVB3 myocarditis can lead to dilated cardiomyopath (DCM). DCM is one of the leading causes of the need for heart transplantation, so it is important to understand the life cycle of CVB3 and its interactions with the host cell. Infection causes rapid death of host cardiomyocytes by altering normal cellular homeostasis for the efficient release of progeny virion. In this chapter, we will examine the impact that CVB3 replication has on host cell biology, from events that take place at receptor ligation to progeny virus release. The primary focus will be on the myriad of signalling pathways that are activated at all stages of virus replication and their downstream effects. We will also discuss some of the extracellular effects of infection as well as immune and matrixmetalloprotease activation. Interactions of host cell proteins with the 5' untranslated region (UTR) are required for translation and replication of CVB3. These interactions do not always benefit the virus since the interactions of a 28-kDa host protein with the 5' UTR are thought to be responsible for inhibitory activity against CVB3. Finally, we will discuss how the elucidation of the different stages of replication has provided the opportunity to develop novel strategies for combating CVB3 infection.

Coxsackieviruses and quasispecies theory: evolution of enteroviruses

Enterovirus populations display quasispecies dynamics, characterized by high rates of mutation and recombination, followed by competition, selection, and random drift acting on heterogeneous mutant spectra. Direct experimental evidence indicates that high mutation rates and complex mutant spectra can serve for the adaptation of enteroviruses to complex environments. Studies with the RNA-dependent RNA polymerase of picornaviruses suggest that multiple enzyme sites may influence the template-copying fidelity (incorporation of incorrect vs correct nucleotide) during RNA replication. Mutation and recombination are an unavoidable consequence of the molecular mechanisms inherent to the process of viral genome replication and underlie the diversification of enterovirus genomes as they multiply in human and animal hosts. The diversity of disease manifestations associated with closely related enteroviruses is probably attributable to profound biological effects of some mutations that, because of their limited number, do not necessarily affect the phylogenetic position of the virus. The combination of highly dynamic mutant spectra with unpredictable alterations of biological behavior by minimal genetic change defies classical classification schemes. The result is the need to update the grouping of enteroviruses quite frequently into genetic and serological types and subtypes. The tolerance of enterovirus genomes to remain replication-competent despite multiple mutation and recombination events encourages the engineering of live-attenuated vaccines. Also, the application of quasispecies theory to an understanding of the limits of viral genomes to accept mutations, together with an increasingly deeper understanding of the mechanisms of mutagenesis by nucleoside analogs, has paved the way for the application of lethal mutagenesis as a new antiviral strategy.

Recombinant coxsackievirus vectors for prevention and therapy of virus-induced heart disease

Cardiovascular diseases are the major cause of human death and have been linked to many different risk factors. Among them, coxsackievirus B3 (CVB3), as a member of the enterovirus group, is one of the most important infectious agents of virus-induced myocarditis. Despite the fact that the molecular structure of this pathogen has been characterized very precisely, there is no virus-specific preventive or therapeutic procedure against CVB3-induced heart disease in clinical use today. A promising approach to prevent CVB3-caused myocarditis represents the mutation of the viral genome in a way that coding sequences of cytokines are integrated into the viral RNA. Recombinant cytokine-expressing CVB3 variants were established to increase the local cytokine concentration and to modulate TH1-/TH2-specific immune responses. Especially protective against CVB3-induced murine myocarditis is the application of an interferon-gamma (IFN-gamma)-expressing recombinant coxsackievirus variant. The local and simultaneous expression of an immuno-relevant cytokine by the virus itself induces a strong and long-lasting immune response which protects laboratory animals against lethal infections.

[Short interfering RNA-mediated inhibition of coxsakievirus B3 infection in vitro]

OBJECTIVE

To evaluate feasibility of inhibiting coxsackievirus B3 (CVB3) infection at cellular, protein and gene levels by using small interfering RNA (siRNA).

METHODS

Antiviral activities of siRNAs were evaluated by observing cytopathic effect (CPE), using plaque reduction Western blotting assays and RT-PCR.

RESULTS

Eight siRNAs were synthesized, among them, SiRNA-2, SiRNA-3, SiRNA-6 and SiRNA-7 which were targeted against sequences located in 2B, VP4, 2A and 3C section of CVB3 genome, were designed to have different effect of inhibiting CVB3 infection in vitro. SiRNA-2 showed the best protective effect, 95 percent inhibition of CVB3 cytopathic effect and plaque forming effect was observed at 0.0001 MOI, viral protein synthesis and replication were inhibited. SiRNA-2 showed 30 percent inhibition of virus at 0.1 MOI, 70 percent inhibition at 0.01 MOI, 88 percent inhibition at 0.001 MOI, and 99 percent inhibition at 0.0001 MOI 48 hours after CVB3 infection.

CONCLUSION

SiRNA could effectively inhibit CVB3 infection in vitro, siRNA-2, which is targeted against sequence in 2B section of CVB3 genome, seemed to be the best one among those synthesized in this study.

Coxsackievirus B3 and adenovirus infections of cardiac cells are efficiently inhibited by vector-mediated RNA interference targeting their common receptor

As coxsackievirus B3 (CoxB3) and adenoviruses may cause acute myocarditis and inflammatory cardiomyopathy, isolation of the common coxsackievirus–adenovirus-receptor (CAR) has provided an interesting new target for molecular antiviral therapy. Whereas many viruses show high mutation rates enabling them to develop escape mutants, mutations of their cellular virus receptors are far less likely. We report on antiviral efficacies of CAR gene silencing by short hairpin (sh)RNAs in the cardiac-derived HL-1 cell line and in primary neonatal rat cardiomyocytes (PNCMs). Treatment with shRNA vectors mediating RNA interference against the CAR resulted in almost complete silencing of receptor expression both in HL-1 cells and PNCMs. Whereas CAR was silenced in HL-1 cells as early as 24 h after vector treatment, its downregulation in PNCMs did not become significant before day 6. CAR knockout resulted in inhibition of CoxB3 infections by up to 97% in HL-1 cells and up to 90% in PNCMs. Adenovirus was inhibited by only 75% in HL-1 cells, but up to 92% in PNCMs. We conclude that CAR knockout by shRNA vectors is efficient against CoxB3 and adenovirus in primary cardiac cells, but the efficacy of this approach in vivo may be influenced by cell type-specific silencing kinetics in different tissues.

Coxsackievirus-induced myocarditis in mice: a model of autoimmune disease for studying immunotoxicity

Excellent animal models are available for virus-induced and autoimmune heart disease that are remarkably similar to human disease. Developing good animal models for heart disease is crucial because cardiovascular disease is now the leading cause of death in the United States and is estimated to be the leading cause of death in the world by the year 2020. A significant proportion of heart disease in Western populations is associated with inflammation. Myocarditis, or inflammation of the heart muscle, is the major cause of sudden death in young adults. Although most individuals recover from acute myocarditis, genetically susceptible individuals may go on to develop chronic myocarditis and dilated cardiomyopathy (DCM) resulting in congestive heart failure. In this article, we describe a model of autoimmune myocarditis and DCM induced by inoculation with heart-passaged coxsackievirus B3 (CVB3). Intraperitoneal inoculation of susceptible mice with CVB3 induces acute cardiac inflammation from days 7 to 14 postinfection (pi) that progresses to chronic myocarditis and DCM from day 28 to at least 56 pi. The model of CVB3-induced myocarditis presented here allows dissection of the contribution of viral infection and xenobiotics on immune dysregulation and inflammation in the heart. An improved understanding of the interaction between environmental exposures and the development of heart disease represents a clear challenge for immunotoxicologists.

Strand-specific silencing of a picornavirus by RNA interference: evidence for the superiority of plus-strand specific siRNAs

RNA interference triggered by small interfering RNAs (siRNAs) can be used to effectively contain viral spread. Here, we report on the mechanism of action of siRNAs targeting the medically important coxsackievirus B3 (CVB-3) as a typical representative of viruses with a non-segmented RNA genome in positive-strand orientation. Antiviral siRNAs can be designed to target the genomic (+)-strand, the (-)-strand that occurs as a replication intermediate, or both. In the present study, two complementary and systematic approaches are presented providing direct evidence that silencing of the viral (+)-strand is the key to inhibit CVB-3: first, we used rational siRNA design to direct silencing activity specifically against either of the two viral strands. As a second approach, we employed siRNA containing modified nucleotides to render them specific for one of the virus RNAs. Experiments with infectious coxsackievirus revealed that the inhibitory efficiency correlates exclusively with the activity of the siRNAs directed against the viral (+)-strand. Our finding that only (+)-strand specific siRNAs exert significant antiviral potency may hold true for other RNA viruses with (+)-stranded genomes as well and may therefore be helpful in the development of efficient strategies to inhibit virus propagation.

Virus receptor trap neutralizes coxsackievirus in experimental murine viral myocarditis

OBJECTIVE

The coxsackie and adenovirus receptor (CAR) and the decay-accelerating factor (DAF) are receptors for coxsackievirus B3 (CVB3), which is known as the major cause of human viral myocarditis. We investigated the potential for therapeutic use of soluble virus receptor fusion proteins.

METHODS

We designed and generated a novel virus receptor trap (hCAR-hDAF:Fc) consisting of both CVB3 receptors and the Fc portion of human IgG1 and evaluated its antiviral effects in experimental CVB3 myocarditis.

RESULTS

Among four soluble virus receptor fusion proteins (hCAR:Fc, hDAF:Fc, hCAR-hDAF:Fc and hDAF-hCAR:Fc), hCAR:Fc and hCAR-hDAF:Fc in the supernatant of transfected cells neutralized echovirus, adenovirus, and various serotypes of CVB in a dose-dependent manner. Both soluble viral receptor proteins bound to the VP0 and VP1 capsid proteins of CVB3. The in vivo efficacy of viral receptor proteins was evaluated by intramuscular injection of plasmid (hCAR:Fc or hCAR-hDAF:Fc) followed by electroporation in a murine model of CVB3 myocarditis. Serum levels of the virus receptor proteins increased relative to baseline values from day 3 and peaked on day 14 at 12.9-fold for hCAR:Fc and 7.1-fold for hCAR-hDAF:Fc. The 3-week survival rate was significantly higher in hCAR-hDAF:Fc-treated mice (61%) than in hCAR:Fc-treated mice (29%) and in controls (15%; p<0.05). Myocardial inflammation, fibrosis, and myocardial virus titers were all significantly reduced in the hCAR:Fc and hCAR-hDAF:Fc groups compared to the controls.

CONCLUSION

Our soluble virus receptor trap, hCAR-hDAF:Fc, attenuated viral infection, myocardial inflammation, and fibrosis, resulting in higher survival rates in mice with coxsackieviral myocarditis. Furthermore, it consists exclusively of human components, and we demonstrated that this soluble virus receptor trap may be used as a potential candidate for a novel therapeutic agent for the treatment of acute viral myocarditis during the viremic phase.

TNFR-Fc fusion protein expressed by in vivo electroporation improves survival rates and myocardial injury in coxsackievirus induced murine myocarditis

Tumor necrosis factor-alpha (TNF-alpha) is one of the major cytokines that modulate the immune response in viral myocarditis, but its role has not yet been thoroughly evaluated. We antagonized TNF-alpha using the expressed soluble p75 TNF receptor linked to the Fc portion of the human IgG1 gene (sTNFR:Fc) by in vivo electroporation, and evaluated its effects on experimental coxsackieviral B3 (CVB3) myocarditis. A plasmid DNA encoding sTNFR:Fc (15microg/mouse) was injected into the gastrocnemius muscles of Balb/C male mice followed by electroporation (day -1). Control mice were injected with an empty vector. One day after electroporation, mice were infected with CVB3 (day 0). Serum levels of sTNFR:Fc increased from day 2 and peaked at day 5 following electroporation. The heart virus titers of sTNFR:Fc mice were higher than those of controls at day 3. However, subsequent to day 12, the survival rates of the sTNFR:Fc mice were significantly higher than those of the controls (36% versus 0% at day 27, P<0.01). Histopathological examination indicated that inflammation and myocardial fibrosis were significantly decreased in sTNFR:Fc mice at day 12. The expressed sTNFR:Fc could modulate the inflammatory process during the post-viremic phase of viral myocarditis.

Plasma concentrations of cytokines and neurohumoral factors in a case of fulminant myocarditis successfully treated with intravenous immunoglobulin and percutaneous cardiopulmonary support

A 53-year-old Japanese man with fulminant myocarditis was referred. Percutaneous cardiopulmonary support (PCPS) was introduced immediately and intravenous immunoglobulin (IVIG) therapy followed for 2 days. Cardiac function showed signs of recovery on the 4th hospital day and the patient was weaned from PCPS on the 7th hospital day. Creatine kinase-MB peaked at 12 h after admission and was 176 ng/ml. Endomyocardial biopsy showed active myocarditis. A marked increase of the neutralizing antibody titer suggested coxsackievirus B3 infection. Plasma concentrations of cytokines and neurohumoral factors were analyzed. Proinflammatory cytokines, such as interleukin (IL)-1beta, IL-6 and tumor necrosis factor (TNF-alpha), and anti-inflammatory cytokines, such as IL-1 receptor antagonist, soluble TNF receptor-1 and IL-10, were elevated on admission and all had decreased on the 7th hospital day. Brain natriuretic peptide and noradrenaline were already elevated upon admission (1,940 pg/ml and 4.6 ng/ml, respectively) and decreased thereafter. Although IVIG therapy under PCPS is a common treatment for fulminant myocarditis, the immunological response in vivo remains unclear. This case demonstrated suppression of serum cytokines after IVIG and PCPS treatment. Immunological parameters in those who have been treated with IVIG and PCPS and survived without complications are of great value for evaluation of the therapy. Further analysis with more cases in a multicenter study is necessary.

Maintaining Inhibition: siRNA Double Expression Vectors Against Coxsackieviral RNAs

The potential of RNA interference (RNAi) to inhibit virus propagation has been well established in recent years. In several studies, however, emergence of viral escape mutants after prolonged exposure to RNAi has been observed, raising a major hurdle for a possible therapeutic application of this strategy. Here, we report the design and characterisation of a vector that allows the simultaneous expression of two short hairpin RNAs (shRNAs), thereby maintaining high silencing activity even against a viral RNA bearing mutations in one of the target sites. Two short interfering RNAs (siRNAs) against the 3D-RNA dependent RNA polymerase of coxsackievirus B3 were identified that displayed efficient inhibition of virus propagation in HeLa cells and reduced the virus titre by up to 90%. We generated two expression vectors encoding these newly identified siRNAs and evaluated their silencing efficiency against the target gene in a reporter assay. Viral escape was then simulated by introducing a point mutation into either of the target sites. This substitution led to complete abrogation of silencing by the respective vector. To bypass this blockade of silencing, an siRNA double expression vector (SiDEx) was constructed to achieve simultaneous expression of both siRNAs from one plasmid. The silencing efficiency of both siRNAs generated by SiDEx was comparable to that of the individual mono-expression vectors. In contrast to the conventional expression vectors, SiDEx displayed substantial gene regulation also of the mutated target RNA. As our approach of expressing various shRNAs from one vector is based on a simple and universally applicable cloning strategy, SiDEx may be a helpful tool to achieve sustained silencing of viruses, ultimately reducing the risk of emergence of viable mutants. An additional application of SiDEx vectors will be the simultaneous knockdown of two targeted genes for functional studies.

Immunomodulatory treatment strategies in inflammatory cardiomyopathy: current status and future perspectives

Chronic autoimmunity and viral persistence constitute prognostic factors for adverse outcome in dilated cardiomyopathy patients. Inflammatory cardiomyopathy is a specific cardiomyopathy entity diagnosed in approximately 50% of dilated cardiopmyopathy patients by immunohistological quantification of immunocompetent infiltrates and cell adhesion molecule abundance. Patients with autoimmune inflammatory cardiomyopathy benefit from immunosuppressive treatment and immunoadsorption by improvement of left ventricular ejection fraction and heart failure symptoms, paralleled by a significant suppression of intramyocardial inflammation. However, dilated cardiomyopathy patients with viral persistence do not respond favorably to immunosuppression.

Neonatal coxsackie B virus infection-a treatable disease?

Ten neonates with coxsackie B viral infection presented over a 3-month period. Clinical features included meningoencephalitis, thrombocytopenia, disseminated intravascular coagulopathy, cardiomyopathy, and hepatitis. Eight infants had multiorgan disease, four with severe myocardial dysfunction, of whom two died. All of the infants with severe disease developed symptoms within 7 days of age. In infants presenting within 10 days of birth, in all cases there were symptoms compatible with maternal infection prior to delivery. Severity was associated with perinatal transmission. Enteroviral polymerase chain reaction of CSF, urine, stool or throat swab was positive in nine of the ten babies. Seven of the infants were treated with a 7-day course of the new anti-picornaviral drug pleconaril (5 mg/kg 3 times daily).

CONCLUSION

These cases highlight the importance of not missing coxsackie B viral infection in the differential diagnosis of the septic neonate, especially as there is now a potential treatment.

Severe rhabdomyolysis and acute renal failure following recent Coxsackie B virus infection

Viral infections have been associated with a wide spectrum of muscle disorders, ranging from acute nonspecific myalgia to myositis. However, severe rhabdomyolysis, with or without accompanying acute renal failure (ARF), has been described only rarely. We report the fourth case in the literature of recent Coxsackie B virus infection complicated by severe rhabdomyolysis and ARF, necessitating temporary haemodialysis in a previously healthy young man. Although most Coxsackie B virus infections are asymptomatic, one should be aware of this potentially life-threatening complication of this virus. As illustrated with the present case, serological testing may reveal the diagnosis in a case of rhabdomyolysis after a viral illness.

T-cell receptor V beta 8.1 peptide reduces coxsackievirus-induced cardiopathology during murine acquired immunodeficiency syndrome

Infection of people with human immunodeficiency virus (HIV) as well as LP-BM5 infection in mice results in progressive deterioration of the immune system in the majority of untreated hosts. Peptide immunotherapy has been shown to be effective in the stimulation or immunoregulation of T-helper 1 (T(H)1) and T-helper 2 (T(H) 2) response subsets. In murine acquired immunodeficiency syndrome (AIDS), T(H)1 deficiency enables the host to be susceptible to coxsackievirus infection, inducing cardiopathology in a short period. T-cell receptor (TCR) Vbeta8.1 peptide, a 16-mer peptide containing the entire CDR1 segment and part of the FR2 region of human Vbeta8, showed both an immunoregulating and immunostimulating effect in murine AIDS. TCR Vbeta8.1 peptide acts on T cells promoting interleukin-2 production and therefore enhancing a cell-mediated immune response. It retarded development of cardiopathology due to coxsackievirus infection. Retrovirus-infected mice treated with the peptide showed a longer life span than the nontreated, retrovirus-infected animals.

Viral myocarditis and dilated cardiomyopathy: mechanisms, manifestations, and management

Viral infection of the heart is relatively common and usually of little consequence. It can, however, lead to substantial cardiac damage and severe acute heart failure. It can also evolve into the progressive syndrome of chronic heart failure. Recent studies have gone some way towards unravelling the complex mechanisms underlying the heart muscle damage that occurs after viral infection. These studies have lent support to both immune and viral mediated (independent of an immune response) cardiac damage. Acute myocarditis can present in various ways, and it may be a cause of sudden death in an otherwise healthy young adult. New treatments for viral heart disease are awaited. In the meanwhile, the haemodynamic support of patients with acute left ventricular failure caused by myocarditis should be aggressive, to allow for the possibility of spontaneous recovery. Contemporary trials of treatment in chronic heart failure secondary to dilated cardiomyopathy support the use of angiotensin converting enzyme inhibitors, beta adrenoceptor blockers, and spironolactone in such patients.

Viral myocarditis presenting with seizure and electrocardiographic findings of acute myocardial infarction in a 14-month-old child

Acute viral myocarditis is an uncommon but potentially fatal illness in children. Patients with myocarditis may present with nonspecific symptoms or atypical findings that make diagnosis in the emergency department difficult. We describe a previously healthy 14-month-old child with difficulty breathing and a tonic-clonic seizure who was subsequently found to have ECG changes and cardiac marker elevation consistent with acute myocardial infarction. The patient was immediately transferred from our community hospital ED to our tertiary care children's hospital. Shortly after admission, the patient developed intractable nonperfusing ventricular arrhythmias necessitating extracorporeal membrane oxygenation. Cardiac function did not recover, and the patient required heart transplantation before cessation of bypass. Serology and anatomic pathology confirmed coxsackievirus B myocarditis. This case illustrates (1) the nonspecific presentation of myocarditis as dyspnea and seizure, (2) the manner in which myocarditis can mimic myocardial infarction, and (3) the importance of early diagnosis in the ED and transfer to a tertiary care facility.

Enteroviral infection causing fatal myocarditis and subclinical myopathy

Enteroviral RNA detection in myocarditis and dilated cardiomyopathy is rare. Enteroviral particles and RNA have recently been identified in patient's skeletal muscle, suggesting that skeletal more than heart muscle hosts the virus in chronic infection. Enteroviral RNA and virus-like particles were found in the myocardium and in the skeletal muscle of two patients with fatal myocarditis: a 39 year old man who died five days after the onset of febrile flu; and a 49 year old woman, assisted for 50 days with a left ventricular assist device, who then died from cerebral haemorrhage. Automated sequencing, alignment, and sequence comparison confirmed the enteroviral origin of polymerase chain reaction products and excluded contamination. These findings agree with prior observations of enteroviral localisation in the skeletal muscle of patients with dilated cardiomyopathy, and further support the hypothesis that skeletal rather than heart muscle may host the virus and serve as a reservoir in cardiomyopathies related to chronic infection.

KEYWORDS

enterovirus; myocarditis; viral particles; skeletal muscle

The role of B lymphocytes in coxsackievirus B3 infection

Coxsackieviruses are important human pathogens, frequently causing myocarditis, pancreatitis, and a variety of less severe diseases. B lymphocytes appear central to the interaction between these viruses and their mammalian hosts, because agammaglobulinemic humans, genetically incapable of antibody production, are susceptible to chronic infections by coxsackieviruses and related enteroviruses, such as poliovirus and echovirus. However, recent studies show that Type B coxsackievirus (CVB) infects B lymphocytes soon after infection, suggesting the possibility that these cells may play some role in virus dissemination and/or that the virus may be able to modulate the host immune response. We analyzed the role of B lymphocytes in CVB infection and confirmed that CVB infects B lymphocytes, and extended these findings to show that this is a productive infection involving approximately 1 to 10% of the cells; however, infectious center assays show that other splenocytes are infected at approximately the same frequency. Virus is readily detectable by in situ hybridization in the spleen of immunocompetent mice but is difficult to detect in mice deficient in B cells (BcKO mice), consistent with much of the splenic signal being the result of B cell infection. Surprisingly, given the extent of their infection, B cells express barely detectable levels of the murine coxsackievirus-adenovirus receptor (mCAR), suggesting that another means of cell entry may be used. We found no evidence of B cell depletion following CVB infection, indicating that this is not the explanation for the transient immunosuppression previously reported. Virus replication and dissemination are slightly delayed in BcKO mice, consistent with B cells' playing a role as an important early target of infection and/or a means to distribute the virus to many tissues. In addition, we show that BcKO mice recapitulate a central feature of human agammaglobulinemia: CVB establishes chronic infection in a variety of organs (heart, liver, brain, kidney, lung, pancreas, spleen). In most of these tissues the viral titers remain high (10(5)-10(8) plaque forming units (pfu) per gram of tissue) for the life of the mouse, and in several there is severe pathology, particularly severe myocardial fibrosis with ventricular dilation, reminiscent of the dilated cardiomyopathy seen in humans with chronic enteroviral myocarditis. Transfer of B and/or T cells from non-immune mice had no discernible effect, whereas equivalent transfers from immune mice often resulted in transient or permanent disappearance of detectable CVB.

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.

[Syncope in 3rd degree atrioventricular block. Detection of virus genome in the myocardium]

HISTORY AND CLINICAL FINDINGS

A 28-year-old woman was admitted after syncope which had been preceded by several flulike episodes. There was no history of any other serious disease. Physical examination was unremarkable. Heart sounds were regular and normal, there were no murmurs.

INVESTIGATIONS

White cell count was 9400/microliter, with a normal differential count. Erythrocyte sedimentation rate and C-reactive protein were also normal. Virus serology revealed no abnormality. The electrocardiogram (ECG) showed complete (third degree) atrioventricular (AV) block with an idioventricular rhythm of 38 beats/min and right bundle branch block pattern.

TREATMENT AND COURSE

A temporary transvenous pacemaker was inserted on the first hospital day. As myocarditis was suspected a right ventricular endomyocardial biopsy was obtained. Histological and immunohistological examinations demonstrated no unequivocal findings. But molecular-biological tests revealed. Coxsackie-B3 virus genome. The pacemaker was removed on the 6th day, when the ECG had shown intermittent second degree AV block. Regular sinus rhythm with a PR interval of 0.18 s was recorded on day 12, and 24-hour ECG monitoring for several days until her discharge on the 18th day confirmed this rhythm throughout.

CONCLUSION

In aetiologically undetermined disease molecular-biological techniques can be indispensable for the exact diagnosis and may be decisive for administering specific treatment.

Failure of treatment with interleukin-2 receptor-specific monoclonal antibody in acute coxsackievirus B3 myocarditis in mice

T cell activation is assumed to play a crucial role in many viral infections. An important marker for the activation of T cells is the interleukin-2 receptor (IL-2R); resting T lymphocytes do not bear detectable amounts of IL-2R. AMT13, a rat monoclonal antibody against mouse IL-2R, inhibits interleukin-2-dependent cell growth both in vitro and in vivo. Therefore, to clarify the effects of anti-IL-2R antibody treatment upon coxsackievirus B3 (CB3)-infected C3H/He mice, AMT13, 1 microg/mouse per day, was administered, subcutaneously, starting on day 0 (group 2) in experiment I or on day 7 (group 4) in Experiment II for 7 days, respectively. Groups 1 and 3 were examined as infected controls. In both experiments, there was no significant difference in mortality or in the severity of myocarditis between the treated and the untreated groups. Also, myocardial CB3 titers on day 7 did not differ significantly between groups 1 and 2. In addition, the distribution of activated T cell subsets in the inflamed myocardium was not changed by the treatment, and the paucity of myocardial IL-2R-positive cells was confirmed in all groups. Effects of the antibody treatment were confirmed by a decrease in delayed type hypersensitivity. Although some reports have shown that anti-IL-2R antibody has been successfully applied to ameliorate acute renal graft-versus-host disease, to enhance survival of skin allografts, and to suppress diabetic insulitis, it did not exert a beneficial effect on acute CB3 myocarditis in mice.

Subclassification of dilated cardiomyopathy and interferon treatment

Seventy-seven consecutive patients with dilated cardiomyopathy underwent left ventricular endomyocardial biopsy. In 20 biopsies (26%) enteroviral RNA was detected by in-situ hybridization. After an average observation period of more than 2 years only one patient had died in the enterovirus positive (ev+) group compared with 11 deaths and four heart transplantations in the enterovirus negative (ev-) group. After a mean follow-up of 16 +/- 9 months haemodynamic evaluation of the surviving ev+ patients showed significantly better results with respect to left ventricular ejection fraction and left ventricular end-diastolic diameter. The four ev+ patients with haemodynamic deterioration were given interferon-alpha, 3 million units subcutaneously every other day for six months. No severe side effects were seen and all four patients improved according to their haemodynamic and clinical parameters. In two of the four patients enteroviral RNA was not detectable in a subsequent biopsy.

A case of protracted coxsackie virus meningoencephalitis in a marginally immunodeficient child treated successfully with intravenous immunoglobulin

A child with acute lymphocytic leukemia who was in clinical remission and developed coxsackie B4 meningoencephalitis is presented. Despite minimal evidence of immunodeficiency, the patient had progression of neurologic disease clinically, electroencephalographically and on laboratory evaluation of spinal fluid. A dramatic response to the use of intravenous immunoglobulins is reported and its rationale explained.

Enterovirus-induced myocarditis: hemodynamic deterioration with immunosuppressive therapy and successful application of interferon-alpha

In 1985, myocarditis was diagnosed by endomyocardial biopsy in a 53-year-old woman who was free of symptoms of heart insufficiency. Immunosuppressive therapy with azathioprine and prednisolone was prescribed as the patient had deteriorated to NYHA II heart insufficiency in March 1986. When application of immunosuppressive agents was terminated in 1987, serial endomyocardial biopsies revealed no signs of myocarditis, thus indicating effectiveness of immunosuppression. Nevertheless, the patient had worsened clinically and hemodynamically. At follow-up in 1991, the patient had progressed to dilated cardiomyopathy resulting in NYHA III heart insufficiency. Enterovirus infection of the heart was detected by in situ nucleic acid hybridization. In addition, retrospective serology indicated a significant increase of coxsackievirus B2 antibodies between 1985 and 1991. Investigational antiviral therapy with recombinant interferon alpha-2a was tolerated well and a favorable clinical, hemodynamic, and virologic response was observed. Thus, progression of biopsy-proven myocarditis to dilated cardiomyopathy may have been facilitated by immunosuppressive therapy in enterovirus infection. Antiviral therapy might be advantageous in patients with enterovirus myocarditis and dilated cardiomyopathy.

Cytokine and murine coxsackievirus B3 myocarditis. Interleukin-2 suppressed myocarditis in the acute stage but enhanced the condition in the subsequent stage

BACKGROUND

It has been shown that the development of coxsackievirus B3 (CB3) myocarditis is regulated by T cells and not by B cells. Interleukin-2 (IL-2) is a T-cell-derived cytokine that stimulates the growth of T cells. This study was carried out to determine the effects of IL-2 on CB3-infected BALB/c mice.

METHODS AND RESULTS

In two separate experiments, recombinant human IL-2 (5 x 10(4) U) was administered subcutaneously to 30 mice early (days 0 to 7) and 30 mice late (days 7 to 14) after infection with CB3. Each experiment had a control group of infected animals that did not receive IL-2. On days 7 and 10, splenic natural killer (NK) cell activity determined by 51Cr release assay and the distribution of myocardial lymphocyte subsets were compared in the treated and untreated groups. In the early treatment experiment, survival at 7 days was higher in treated compared with control animals, myocardial virus titers were lower, inflammatory cell infiltration was less (as was the severity of necrosis at the time the mice were killed), and NK cell activity was higher. However, in the late treatment experiment, survival at 14 days was lower in treated compared with control animals, and there was more infiltration, more severe necrosis, and more T-cell infiltration, but the NK cell activity did not differ significantly. In a third experiment similar to the late experiment described above but involving infected athymic nude mice, we confirmed the lack of effect of late in vivo administration of IL-2 on outcome.

CONCLUSIONS

IL-2 has the capacity to limit CB3 myocarditis by enhancing NK cell activity in the acute viremic stage, resulting in a reduction of cardiac pathology. However, in the subacute aviremic stage, in contrast, IL-2 exacerbates the course and severity of the disease by increasing the number of T cells infiltrating the myocardium. That is, IL-2 has differential effects on acute CB3 myocarditis. IL-2 is beneficial if treatment is given early but later in murine CB3 myocarditis.

Neonatal coxsackievirus group B infections: experience of a single department of neonatology

Coxsackie infections in 14 infants born in a single neonatal unit were studied. The clinical presentation was mild nonspecific disease in eight infants and an overwhelming multiorgan disease in six. Three infants with systemic disease died. Vertical transmission of the virus from a colonized mother was documented in five mothers who infected seven infants. The remaining seven infants were infected horizontally, presumably from infected personnel. Coxsackie B1 was isolated in four of the cases and type B3 in two cases of systemic disease. Intravenous gammaglobulin combined with human leukocyte interferon was utilized in three cases of overwhelming disease and two infants of these infants survived.

[The clinical diagnosis and treatment of meningitis caused by Coxsackie B viruses]

Clinical features of meningitis caused by Coxsackie virus B were analyzed in 369 adult patients. The authors draw attention to polymorphism of manifestation and diagnostic signs of the diseases. Reaferon used in complex treatment was established to be the most effective. The drug considerably shortened period of fever and drove away main clinical symptoms.

[Acute hemorrhagic viral conjunctivitis]

Two cases of acute hemorrhagic conjunctivitis are described, in which the enterovirus Coxsackie 24 was found by serological examination to be the etiological agent. The virus was important from Nigeria. The patients suffered by the acute hemorrhagic keratoconjuntivitis with transient iritic irritation without the systemic symptoms. Since now this disease with serological verification was not diagnosed in our country. The question of the viral hemorrhagic conjunctivitis and their treatment is discussed. The necessity of virological investigation in inflammations of the anterior segment is stressed.

Acute hemorrhagic conjunctivitis

Acute hemorrhagic conjunctivitis, an infection caused by enterovirus 70 and a variant of coxsackievirus A24, is characterized by the rapid onset of severely painful conjunctivitis and subconjunctival hemorrhage. The condition is usually benign and resolves in five to seven days; however, a polio-like paralysis (radiculomyelitis) develops in approximately one in 10,000 patients infected with enterovirus 70. No treatment is available. Information about acute hemorrhagic conjunctivitis should be provided to patients and the community in order to prevent undue alarm, discourage home remedies and control the spread of this highly contagious disease.

Treatment of experimental murine Coxsackie B3 myocarditis

Using the murine model of coxsackievirus B3-induced myocarditis we studied the effects of various immunosuppressive agents on the course and outcome of the disease in genetically different strains of mice. The response to drug treatment varied greatly among the strains of inbred mice, which suggests different immune pathomechanisms operative in mediating myocarditis.

Immunosuppression with high doses of cyclophosphamide reduces the severity of myocarditis but increases the mortality in murine Coxsackievirus B3 myocarditis

To test the therapeutic efficacy of immunosuppression with cyclophosphamide (CYP) on coxsackievirus B3 (CB3) myocarditis, 2-week-old DBA/2 mice were inoculated with 3 X 10(2) plaque-forming units of CB3 virus. CYP (100 mg/kg/day s.c.) was administered daily on days 0-8 (experiment 1; group 2), days 8-21 (experiment 2; group 4), and days 21-34 (experiment 3; group 6). Groups 1, 3, and 5 were infected control groups for each experiment. Spleen, thymus, and body weights were measured. In experiment 1, survival rate in group 2 on day 8 was low compared with group 1 (nine of 51 versus eight of 28; p = NS), and myocardial virus titers in group 2 on day 8 were higher (p less than 0.05) compared with group 1; however, cellular infiltration and myocardial necrosis in group 2 were less severe (p less than 0.05), and serum neutralizing antibody titers were decreased (p less than 0.01). In experiment 2, survival rate in group 4 on day 21 was significantly lower (six of 24 versus 12 of 16; p less than 0.01), but cellular infiltration, myocardial necrosis, and calcification in group 4 were significantly less severe, and serum neutralizing antibody titers were decreased (p less than 0.01). In experiment 3, survival rate, cardiac histopathology, and serum neutralizing antibody titers did not differ between groups 5 and 6. In experiments 1, 2, and 3, the treated groups were characterized by lower spleen-to-body-weight and thymus-to-body-weight ratios and by marked cellular depletion in spleen and thymus.(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of heterotypic virus resistance in adult inbred mice immunized with a variant of Coxsackievirus B3

Infection of adult male C3H/HeJ mice with a host range variant of Coxsackievirus B3 (CB3W-RD) induced resistance in these mice to an otherwise lethal dose of Coxsackievirus B1 (CB1). The protective effect induced by CB3W-RD was detectable as early as 1 day post-vaccination and was still present 10 weeks later. While untreated mice infected with CB1 died within 5 days because of massive hepatic necrosis, the liver was spared in mice immunized with CB3W-RD and then challenged with CB1. In general, CB1 titers in heart, liver, and pancreas of CB3W-RD-vaccinated animals were lower than that found in unvaccinated animals. Virus neutralizing antibody was not a mediator of this heterotypic, virus-induced protective effect. In addition, the outcome of CB1 infection could be modified if superinfection with CB3W-RD took place within 1-4 days following CB1 infection. In this regard, maximum therapeutic efficacy was observed when CB1 infected mice were superinfected 2 days after CB1 infection. CB1-infected mice that survived as a result of treatment with CB3W-RD exhibited liver regeneration but did develop myocardial necrosis.

Clinical outcome and left ventricular function 23 years after acute coxsackie virus myopericarditis

The clinical outcome of 18 patients, who presented with a Coxsackie virus myopericarditis in 1965, was evaluated 23 years later. Five patients had died, two of them had had heart failure. Thirteen patients and 23 healthy control subjects underwent exercise testing with gas exchange analysis. Left ventricular (LV) peak filling rate (PFR) was estimated by digitized M-mode echocardiography. Left ventricular ejection fraction was measured at rest and during exercise by radionuclide angiography. All patients were free of cardiac symptoms. Their clinical examination and the chest X-ray were normal. Peak oxygen consumption was not decreased in the patient group compared with the control group. PFR was significantly lower in the patient group than in the control group, 10.2 +/- 0.4 vs 13.2 +/- 0.4 cm s-1, P less than 0.001 (mean +/- SEM). LV ejection fraction was normal at rest in all patients (58 +/- 1%). An abnormal LV ejection fraction response to exercise was observed in two patients. Our data indicate that long-term prognosis after acute Coxsackie virus myopericarditis is good in a majority of patients.

Monoclonal antibody therapy for prevention of acute coxsackievirus B3 myocarditis in mice

The efficacy of monoclonal antibodies against T cell subsets in the therapy of experimental myocarditis caused by coxsackievirus B3 (CB3) was investigated. Two-week-old male C3H/He mice were inoculated with CB3 virus. Treatment was begun in the viremic stage (starting on the day of inoculation) in experiment 1 and in the later aviremic stage (starting on day 10) in experiment 2. Rat anti-mouse monoclonal antibodies, Lyt 1 (helper/inducer T) at 1 microgram/mouse (group 2 in experiment 1; group 6 in experiment 2), Lyt 2 (suppressor/cytotoxic T) at 1 microgram/mouse (group 3 in experiment 1; group 7 in experiment 2), and Lyt 1 at 1 microgram plus Lyt 2 at 1 microgram/mouse (group 4 in experiment 1; group 8 in experiment 2), were administered subcutaneously daily for 2 weeks. The treatment groups were compared with infected controls (group 1 in experiment 1; group 5 in experiment 2). In experiment 1, the survival rate in group 4 was higher (p less than 0.01) than in group 1. In experiment 2, mice treated with Lyt 1 plus Lyt 2 (group 8) survived significantly longer (p less than 0.05) than did controls (group 5). In experiment 1, myocardial virus titers on days 5 and 6 did not show any significant differences among the four groups. Serum-neutralizing antibody titers between group 1 and group 4 in experiment 1 or between group 5 and group 8 in experiment 2 did not differ significantly. Histologic examination showed extensive myocardial necrosis and cellular infiltration in untreated groups: there was less infiltration in group 4 and in group 8 and less severe necrosis in group 8.(ABSTRACT TRUNCATED AT 250 WORDS)

Protective effect of recombinant alpha interferon on coxsackievirus B3 myocarditis in mice

The effects of recombinant human leukocyte interferon alpha-A/D on experimental myocarditis caused by coxsackievirus B3 were investigated. Four-week-old male C3H/He mice were inoculated intraperitoneally with 10(5.5) 50% tissue culture infective dose (TCD50) in 0.1 ml of coxsackievirus B3 (Nancy strain). Interferon alpha-A/D, 10(4) U/gm/day, was administered subcutaneously daily, starting 1 day before (group 1) or on the day of (group 2) infection. Animals were killed on day 7. The infectivity of myocardial virus was significantly lower in group 1 (0.7 +/- 0.1 log10TCD50/mg, p less than 0.005) and in group 2 (2.5 +/- 1.2 log10TCD50/mg, p less than 0.005) than in control mice (4.4 +/- 0.9 log10TCD50/mg). Results of histologic examination showed extensive myocardial necrosis and cellular infiltration in all mice in the untreated group, but significantly less severe necrosis and infiltration in the treated groups. Thus, interferon alpha-A/D, when given before and simultaneously with virus, effectively inhibited replication of myocardial virus and reduced the inflammatory response and myocardial damage in an experimental model of viral myocarditis.