Evidence of viral infection in the myocardium of American and Japanese patients with idiopathic dilated cardiomyopathy

In Vivo Persistence of Human Rhinoviruses in Immunosuppressed Patients

Several species of the genus Enterovirus cause persistent infections in humans. Human rhinovirus (HRV) infections are generally self-limiting but occasionally persistent infections have been described. This study aimed to identify persistent HRV infections and investigate the clinical and virologic characteristics of patients with persistent infections. From January 2012 to March 2015, 3714 respiratory specimens from 2608 patients were tested for respiratory viruses by using a multiplex reverse transcription–polymerase chain reaction. A retrospective study was performed. Patients with at least two specimens positive for HRV/enterovirus taken 45 days or longer apart were identified and the HRV/enteroviruses were typed. Patients with persistent infection were compared to patients with reinfection and patients with cleared infection. Phylogenetic analysis of the viral protein(VP)4/VP2 region was performed. 18 patients with persistent HRV/enterovirus infection were identified. Minimum median duration of persistence was 92 days (range 50–455 days). All but one patients with persistence were immunosuppressed. Immunosuppression and hematologic disorders were more frequent in patients with persistence (n = 18) than in patients with reinfection (n = 33) and with cleared infection (n = 25) (p = 0.003 and p = 0.001, respectively). In conclusion, this retrospective study identified HRV persistence in vivo which occurred mainly in immunosuppressed patients.

The impact of juvenile coxsackievirus infection on cardiac progenitor cells and postnatal heart development

Coxsackievirus B (CVB) is an enterovirus that most commonly causes a self-limited febrile illness in infants, but cases of severe infection can manifest in acute myocarditis. Chronic consequences of mild CVB infection are unknown, though there is an epidemiologic association between early subclinical infections and late heart failure, raising the possibility of subtle damage leading to late-onset dysfunction, or chronic ongoing injury due to inflammatory reactions during latent infection. Here we describe a mouse model of juvenile infection with a subclinical dose of coxsackievirus B3 (CVB3) which showed no evident symptoms, either immediately following infection or in adult mice. However following physiological or pharmacologically-induced cardiac stress, juvenile-infected adult mice underwent cardiac hypertrophy and dilation indicative of progression to heart failure. Evaluation of the vasculature in the hearts of adult mice subjected to cardiac stress showed a compensatory increase in CD31⁺ blood vessel formation, although this effect was suppressed in juvenile-infected mice. Moreover, CVB3 efficiently infected juvenile c-kit⁺ cells, and cardiac progenitor cell numbers were reduced in the hearts of juvenile-infected adult mice. These results suggest that the exhausted cardiac progenitor cell pool following juvenile CVB3 infection may impair the heart's ability to increase capillary density to adapt to increased load.

Coxsackievirus B (CVB) is a significant human pathogen, causing myocarditis, aseptic meningitis and encephalitis. The lasting consequences of juvenile CVB infection on the developing host have yet to be adequately inspected. Here, we show that CVB efficiently infected juvenile cardiac progenitor cells both in culture and the young heart. Furthermore, we describe a mouse model of juvenile infection with a subclinical dose of CVB which showed no symptoms of disease into adulthood. However following physiological or pharmacologically-induced cardiac stress, juvenile-infected mice underwent cardiac hypertrophy and dilation indicative of progression to heart failure. These results suggest that mild CVB infection in the young host may impair the ability of the heart to adapt to increased load leading to pathological remodeling later in adult life.

Coxsackievirus B4 can infect human pancreas ductal cells and persist in ductal-like cell cultures which results in inhibition of Pdx1 expression and disturbed formation of islet-like cell aggregates

The role of enteroviruses, especially Coxsackievirus B (CVB), in type 1 diabetes is suspected, but the mechanisms of the virus-induced or aggravated pathogenesis of the disease are unknown. The hypothesis of an enterovirus-induced disturbance of pancreatic β-cells regeneration has been investigated in the human system. The infection of human pancreas ductal cells and pancreatic duct cell line, PANC-1, with CVB4E2 has been studied. Primary ductal cells and PANC-1 cells were infectable with CVB4E2 and a RT-PCR assay without extraction displayed that a larger proportion of cells harbored viral RNA than predicted by the detection of the viral capsid protein VP1 by indirect immunofluorescence. The detection of intracellular positive- and negative-strands of enterovirus genomes in cellular extracts by RT-PCR and the presence of infectious particles in supernatant fluids during the 37 weeks of monitoring demonstrated that CVB4E2 could persist in the pancreatic duct cell line. A persistent infection of these cells resulted in an impaired expression of Pdx1, a transcription factor required for the formation of endocrine pancreas, and a disturbed formation of islet-like cell aggregates of which the viability was decreased. These data support the hypothesis of an impact of enteroviruses onto pancreatic ductal cells which are involved in the renewal of pancreatic β-cells.

The therapeutic potential of immune therapy in idiopathic dilated cardiomyopathy

Idiopathic dilated cardiomyopathy (DCM) is a heart muscle disease of unknown origin and the second most common reason for heart transplantation. Genetic factors, viral persistence and the presence of an autoimmune response against myocardial epitopes are believed to play a major pathogenic role in idiopathic DCM. Pathogenic circulating autoantibodies against several cardiac proteins have been detected in sera from idiopathic DCM patients. Accordingly, suppression of autoreactive components of the immune system has been discussed as a prospective therapeutic implement in idiopathic DCM management. Removal of pathophysiologic active autoantibodies by immunoadsorption and subsequent immunoglobulin infusion induces acute and long-term beneficial effects such as improved cardiovascular function and reduced morbidity. Understanding of the amendment in various components of the immune system induced by immunoadsorption therapy may help in elucidating the underlying pathophysiologic mechanisms of the disease. This approach may reveal markers of prognostic value, and new therapeutic approaches could be established.

Toll-like receptor 8 polymorphism and coronary artery disease

Toll-like receptors (TLRs) play roles in innate and adaptive immune responses. Some TLRs are involved in the pathogenesis of cardiovascular diseases. Coronary artery disease (CAD) has an inflammatory and immunological basis. We investigated whether TLR8 Met1Val and TLR8-129G>C single nucleotide polymorphisms (SNPs rs3764879 and rs3764880) are associated with CAD in the Chinese population. We enrolled 412 consecutive patients (185 with coronary stenosis >/=50% or previous myocardial infarction and 227 controls). Ligase detection reaction was performed to detect SNPs rs3764879 and rs3764880 of TLR8. The SNP at rs3764879 is in complete linkage disequilibrium with rs3764880. No significant difference was found in genotypic or allelic frequencies of these two common SNPs between CAD cases and controls (P > 0.05, respectively). No associations existed between these two SNPs and the severity of coronary artery stenosis (All P > 0.05). These results do not support an involvement of SNPs rs3764879 and rs3764880 of TLR8 in predisposition to CAD.

Molecular diagnosis of the viral component in cardiomyopathies: pathophysiological, clinical and therapeutic implications

BACKGROUND

Myocarditis is defined as the inflammation of myocardium associated with cardiac dysfunction. Despite this clear-cut definition, diagnosis and etiologic treatment continue to create considerable debate. Viral infections are frequent causes of myocarditis and there is evidence that persistent viral infection is associated with poor prognosis in different subtypes of cardiomyopathy.

OBJECTIVE

To review methods for diagnosis of viral myocarditis and present the use of polymerase chain reaction (PCR)-based protocols for evaluating viral infection in myocarditis/cardiomyopathies.

METHODS

A review of published literature.

RESULTS/CONCLUSION

There is increasing evidence that PCR-based protocols can provide reliable molecular evidence for the presence of viral infection in myocardium. Thus application of molecular techniques will allow collection and analysis of more information on the epidemiology of viral cardiomyopathies, patient risk stratification and appropriate medical treatment.

Blood dendritic cell levels and phenotypic characteristics in relation to etiology of end-stage heart failure: implications for dilated cardiomyopathy

BACKGROUND

Dysregulation of dendritic cell (DC) mediated immune responses towards auto-antigens, is considered an important feature in the maintenance of experimentally induced heart failure (HF). In order to evaluate the role of blood DCs in cardiomyopathies of different origins, we examined myeloid (mDC) and plasmacytoid (pDC) subset levels and maturation characteristics, according to HF severity and etiology in humans.

METHODS

Absolute numbers of mDCs and pDCs in 12 New York Heart Association (NYHA) class-II, 28 NYHA class III-IV HF patients and 18 healthy controls, were studied by 4-colour whole blood flow cytometry.

RESULTS

End-stage (NYHA III-IV) HF patients had comparable circulating DC subset levels to NYHA-II patients and controls. However, within the NYHA III-IV group total DC levels in patients with non-ischemic dilated cardiomyopathy (DCM) were higher (P<0.001) than in patients with coronary artery disease (CAD), hypertrophic cardiomyopathy (HCM) or other HF etiology. This was due to a significant increase of primarily mDCs (P<0.0001) and to a lesser extent of pDCs (P<0.05) in idiopathic DCM patients, independent of systolic or diastolic cardiac dysfunction. Maturation marker CD83 and lymphoid homing chemokine receptor CCR7 surface expression was enhanced only on mDCs, but not pDCs from DCM patients (P<0.05), compared to patients with CAD, HCM or other underlying cardiac pathophysiology.

CONCLUSIONS

Total blood DC levels in end-stage HF are elevated in patients with DCM. Whole blood DC characterisation may lead to new insights into the pathophysiology of idiopathic DCM in humans.

Association between toll-like receptor 8 expression and adverse clinical outcomes in patients with enterovirus-associated dilated cardiomyopathy

BACKGROUND

In recent reports, human toll-like receptor (TLR) 8 mediates the antiviral response by recognizing single-stranded RNA. The inflammatory response against enteroviral (EV) RNA replication may play an important role in dilated cardiomyopathy (DCM). The purpose of this study was to determine whether TLR8 was expressed with EV replication in patients with enterovirus-associated DCM.

METHODS

Reverse transcriptase-polymerase chain reaction analysis was performed to screen the detection of myocardial EV RNA in 198 consecutive patients with DCM. Seventy-two EV RNA-positive patients with DCM and 20 control samples constituted the study population of the present study. Levels of TLR8 and myeloid differentiation factor (MyD) 88 adaptor protein mRNA and EV RNA (plus- and minus-strand RNAs) were measured by real-time RT-PCR. Immunohistochemistry was performed to identify the cellular source of these molecules.

RESULTS

Toll-like receptor 8 and MyD88 mRNA levels were higher in patients with DCM than in controls (P < .001). Immunostainings of TLR8, MyD88, and EV protein showed localization of these proteins in cardiac myocytes in patients with DCM. After a mean follow-up of 426 days, clinical outcomes (development of heart failure n = 11, cardiac death n = 3) were associated with increased levels of TLR8 and MyD88 (P < .05). Multivariate analysis showed that TLR8 (relative risk 3.2, 95% CI 1.6-6.2) was a strong predictor of heart failure and cardiac death after adjustment for baseline characteristics.

CONCLUSION

Toll-like receptor 8 and MyD88 expressions may be involved in the immune response to EV replication in enterovirus-associated DCM. In addition, TLR8 may provide important prognostic information in patients with enterovirus-associated DCM.

Echovirus infection causes rapid loss-of-function and cell death in human dendritic cells

Coxsackie B viruses (CVB) and Echoviruses (EV) form a single species; Human enterovirus B (HeV-B), within the genus Enterovirus. Although HeV-B infections are usually mild or asymptomatic, they can cause serious acute illnesses. In addition, HeV-B infections have been associated with chronic immune disorders, such as type 1 diabetes mellitus and chronic myocarditis/dilated cardiomyopathy. It has therefore been suggested that these viruses may trigger an autoimmune process. Here, we demonstrate that human dendritic cells (DCs), which play an essential role in orchestration of the immune response, are productively infected by EV, but not CVB strains, in vitro. Infection does not result in DC activation or the induction of antiviral immune responses. Instead, EV infection rapidly impedes Toll-like receptor-mediated production of cytokines and upregulation of maturation markers, and ultimately causes loss of DC viability. These results describe for the first time the effect of EV on the function and viability of human DCs and suggest that infection of DCs in vivo can impede regulation of immune responses.

Myocarditis

Viruses are the most common cause of myocarditis in economically advanced countries.

Enteroviruses and adenoviruses are the most common etiologic agents.

Viral myocarditis is a triphasic process. Phase 1 is the period of active viral replication in the myocardium during which the symptoms of myocardial damage range from none to cardiogenic shock. If the disease process continues, it enters phase 2, which is characterized by autoimmunity triggered by viral and myocardial proteins. Heart failure often appears for the first time in phase 2. Phase 3, dilated cardiomyopathy, is the end result in some patients. Diagnostic procedures and treatment should be tailored to the phase of disease.

Viral myocarditis is a significant cause of dilated cardiomyopathy, as proved by the frequent presence of viral genomic material in the myocardium, and by improvement in ventricular function by immunomodulatory therapy.

Myocarditis of any etiology usually presents with heart failure, but the second most common presentation is ventricular arrhythmia. As a result, myocarditis is one of the most common causes of sudden death in young people and others without preexisting structural heart disease.

Myocarditis can be definitively diagnosed by endomyocardial biopsy. However, it is clear that existing criteria for the histologic diagnosis need to be refined, and that a variety of molecular markers in the myocardium and the circulation can be used to establish the diagnosis.

Treatment of myocarditis has been generally disappointing. Accurate staging of the disease will undoubtedly improve treatment in the future. It is clear that immunosuppression and immunomodulation are effective in some patients, especially during phase 2, but may not be as useful in phases 1 and 3. Since myocarditis is often selflimited, bridging and recovery therapy with circulatory assistance may be effective. Prevention by immunization or receptor blocking strategies is under development.

Giant cell myocarditis is an unusually fulminant form of the disease that progresses rapidly to heart failure or sudden death. Rapid onset of disease in young people, especially those with other autoimmune manifestations, accompanied by heart failure or ventricular arrhythmias, suggests giant cell myocarditis.

Peripartum cardiomyopathy in economically developed countries is usually the result of myocarditis.

Idiopathic Dilated Cardiomyopathy as a Late Complication of Healed Viral (Coxsackie B virus) Myocarditis: Historical Analysis, Review of the Lliterature, and a Postulated Unifying Hypothesis

A historically based literature review of the relationship between acute viral myocarditis and the subsequent development of a dilated cardiomyopathic state is presented. A strong emphasis on a state of definitional ambiguity in the literature as regards the timing of the myopathic state following a viral infection is noted, i.e. does the myopathic state develop acutely and concomitantly with viral myocarditis due to overwhelming viral mediated myocardial cell necrosis, subacutely due to negative remodeling following severe but not overwhelming viral mediated myocardial cell necrosis, subacutely due to a sustained immune mediated myocarditis or in a delayed time frame following complete recovery from the initial infection (i.e. a return of normal histology and the absence of any cellular infiltrate and the presence of normal cardiac function). Evidence for the first two mechanisms is supported by the literature; evidence for the immune mediated chronic myocarditis remains controversial while hard evidence for the development of an idiopathic dilated cardiomyopathy (IDCM) as a late downstream complication following complete recovery from a bout of myocarditis is nonexistent. Recent basic virologic studies of myocarditis and the potential effects of retained noninfectious viral genomic material within the myocardium are reviewed. These studies allow for the proposal of a hypothetical mechanism whereby IDCM develops as a downstream complication of acute viral myocarditis.

Emerging treatments for viral myocarditis

Although viral myocarditis has been mostly attributed to enterovirus and adenovirus infection, the importance of hepatitis C virus has recently been noted. Clinical trials of antiviral agents, such as interferons, are in progress, while new therapies such as viral vaccines, recombinant virus and virus receptors, are in preclinical development. Whereas immunosuppression with corticosteroids or cyclosporin is ineffective, immunosuppressors that do not promote viral replication, such as FTY720, and immunomodulation by interleukin-10, are promising new approaches. Inhibition of nuclear factor-κB, angiotensin II and endothelin effectively suppresses inflammation in experimental viral myocarditis. Embryonic stem cell therapy has been demonstrated to be beneficial; however, this requires further investigation.