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

Serum alarmin S100A8/S100A9 levels and its potential role as biomarker in myocarditis

Aims

The alarmin S100A8/S100A9 (S100A8/A9) is released by activated monocytes/macrophages and neutrophils in the setting lymphocytic myocarditis (MC). We recently demonstrated its therapeutic potential in experimental acute MC. Now, we investigated the diagnostic relevance of S100A8/A9 serum levels in patients with suspected acute and chronic MC and in patients with heart failure without cardiac inflammation.

Methods and Results

Serum S100A8/A9 levels were analysed in patients with a recent onset of MC [≤ 30 days, n = 32; ejection fraction (EF): 45.4 ± 12.9%], dilated cardiomyopathy patients with inflammation (n = 112; EF: 29.0 ± 11.4%), or without inflammation (n = 58; EF: 26.6 ± 9.3%), and controls (n = 25; EF: 68.5 ± 4.6%), by using specific ELISAs. Blood samples were collected at Time Point 1 (T1), where also endomyocardial biopsies (EMBs) were withdrawn. Patients with a recent onset of MC showed a 4.6‐fold increase in serum S100A8/A9 levels vs. controls (MC: 1948 ± 1670 ng/mL vs. controls: 426 ± 307 ng/mL; P < 0.0001). Serum S100A8/A9 correlated with the disease activity, represented by EMB‐derived counts of inflammatory cells (CD3: r = 0.486, P = 0.0047, lymphocyte function‐associated antigen‐1: r = 0.558, P = 0.0009, macrophage‐1 antigen: r = 0.434, P = 0.013), the EMB mRNA levels of S100A8, S100A9 (r = 0.541, P = 0.002), and left ventricular ejection fraction (LVEF: r = 0.498, P = 0.0043). EMB immunofluorescence co‐stainings display macrophages/monocytes and neutrophils as the main source of S100A8 and S100A9 in recent onset MC. The diagnostic value of serum alarmin levels (cut‐off 583 ng/mL) was characterized by a specificity of 92%, a sensitivity of 90.6%, positive predictive value of 93.5%, negative predictive value of 88.5%, and an accuracy of 0.949 (95% confidence interval [0.89–1]). In a subgroup of MC patients, S100A8/A9 serum levels and EMBs at T1 (n = 12) and a follow‐up visit (T2, n = 12, mean follow‐up 8.5 months) were available. A fall of serum S100A8/A9 (T1: 2208 ± 1843 ng/mL vs. T2: 888.8 ± 513.7 ng/mL; P = 0.00052) was associated with a reduced cardiac inflammation (CD3 T1: 70.02 ± 107.4 cells per square millimetre vs. T2: 59.18 ± 182.5 cells per square millimetre; P = 0.0342, lymphocyte function‐associated antigen‐1 T1: 133.5 ± 187.1 cells per square millimetre vs. T2: 74.12 ± 190.5 cells per square millimetre; P = 0.0186, and macrophage‐1 antigen T1: 132.6 ± 129.5 cells per square millimetre vs. T2: 54.41 ± 65.16 cells per square millimetre; P = 0.0015). Serum S100A8/A9 levels were only slightly increased in patients within the chronic phase of MC and in heart failure patients without inflammation vs. controls.

Conclusions

Serum S100A8/A9 might serve as an additional tool in the diagnostic workup of suspected acute MC patients.

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

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

Viral endomyocardial infection is an independent predictor and potentially treatable risk factor for graft loss and coronary vasculopathy in pediatric cardiac transplant recipients

OBJECTIVES

This study sought to evaluate the outcome and prevalence of viral endomyocardial infection after cardiac transplantation.

BACKGROUND

Viral myocardial infection causes heart failure, but its role after cardiac transplantation is unclear. We hypothesized that viral infection of the cardiac allograft reduces graft survival.

METHODS

Between June 1999 and November 2004, 94 pediatric cardiac transplant patients were screened for the presence of viral genome in serial endomyocardial biopsies (EMBs) using polymerase chain reaction (PCR) assays. Graft loss, advanced transplant coronary artery disease (TCAD), and acute rejection (AR) were compared in the PCR-positive (n = 37) and PCR-negative (n = 57) groups, using time-dependent Kaplan-Meier and Cox regression analyses. From November 2002 to November 2004, intravenous immunoglobulin therapy (IVIG) was administered to patients with PCR-positive EMBs. The outcomes of the IVIG-treated, PCR-positive patients (n = 20) were compared with IVIG-untreated, PCR-positive patients (n = 17).

RESULTS

Viral genomes were detected in EMBs from 37 (39%) patients; parvovirus B19, adenovirus, and Epstein-Barr virus (EBV) were the most common. The PCR-positive group (n = 37, 25% graft loss at 2.4 years) had decreased graft survival (p < 0.001) compared with the PCR-negative group (n = 57, 25% graft loss at 8.7 years) and developed advanced TCAD prematurely (p = 0.001). The number of AR episodes was similar in both groups. On multivariate analysis, presence of viral genome was an independent risk factor for graft loss (relative risk: 4.2, p = 0.015). The time to advanced TCAD after becoming PCR-positive was longer in the IVIG-treated patients (p = 0.03) with a trend toward improved graft survival (p = 0.06).

CONCLUSIONS

Viral endomyocardial infection is an independent predictor of graft loss in pediatric cardiac transplant recipients. This effect appears to be mediated through premature development of advanced TCAD. IVIG therapy in this subgroup may improve survival and merits further investigation.

Viral myocarditis: diagnosis, aetiology and management

Myocarditis is an inflammatory disease of the cardiac muscle caused by myocardial infiltration of immunocompetent cells following any kind of cardiac injury. Classic myocarditis mainly occurs as a result of the host's immune response against organisms that cause common infectious illnesses, as a manifestation of hypersensitivity or as a toxic reaction to drug therapy. Chronic inflammatory events may survive successful clearance of initial cardiotoxic agents, be triggered or amplified by autoimmunological processes, or develop in the context of systemic diseases. If the underlying infectious or immune-mediated causes of the disease are carefully defined by clinical and biopsy-based tools, specific immunosuppressive and antiviral treatment options may improve the prognosis of patients with acute and chronic disease.

Adaptive immune responses against parvovirus B19 in patients with myocardial disease

BACKGROUND

Parvovirus B19 (B19V)-DNA is frequently detected in endomyocardial biopsies (EMBs) from patients with acute myocarditis (AMC) and dilated cardiomyopathy (DCM), but also in various healthy tissues. The clinical relevance of this DNA-persistence is unclear.

OBJECTIVES

To investigate potential pathogenic influences of B19V-DNA in EMBs, we analyzed B19V-specific adaptive immune responses in AMC/DCM patients and healthy controls.

STUDY DESIGN

15 AMC/DCM patients with detectable B19V-DNA in EMBs and 51 controls were analyzed for signs of acute B19V-infections and virus-specific immune responses by PCR, ELISA, Western line, and ELISpot-assays.

RESULTS

Productive B19V-infection was determined in three patients. Slightly lower levels of B19V-specific T-cells were observed in patients as compared to the controls, no differences were observed in virus-specific serology. Viral DNA-load in EMBs could not be correlated to the number of B19V-specific T-cells. No differences in T-cell response, viremia and/or serological markers indicative for viral pathogenesis were observed in patients with inflammatory cardiomyopathy.

CONCLUSIONS

Discrepancies in B19V-specific adaptive immunity were not observed in AMC/DCM patients as compared to controls. The data indicate that the exclusive detection of B19V-DNA in EMBs is not sufficient to associate B19V with AMC/DCM but should be complemented with additional virological and immunological parameters in further studies.

Preamplification techniques for real-time RT-PCR analyses of endomyocardial biopsies

Background

Due to the limited RNA amounts from endomyocardial biopsies (EMBs) and low expression levels of certain genes, gene expression analyses by conventional real-time RT-PCR are restrained in EMBs. We applied two preamplification techniques, the TaqMan^® PreAmp Master Mix (T-PreAmp) and a multiplex preamplification following a sequence specific reverse transcription (SSRT-PreAmp).

Results

T-PreAmp encompassing 92 gene assays with 14 cycles resulted in a mean improvement of 7.24 ± 0.33 Ct values. The coefficients for inter- (1.89 ± 0.48%) and intra-assay variation (0.85 ± 0.45%) were low for all gene assays tested (<4%). The PreAmp uniformity values related to the reference gene CDKN1B for 91 of the investigated gene assays (except for CD56) were -0.38 ± 0.33, without significant differences between self-designed and ABI inventoried Taqman^® gene assays. Only two of the tested Taqman^® ABI inventoried gene assays (HPRT-ABI and CD56) did not maintain PreAmp uniformity levels between -1.5 and +1.5. In comparison, the SSRT-PreAmp tested on 8 self-designed gene assays yielded higher Ct improvement (9.76 ± 2.45), however was not as robust regarding the maintenance of PreAmp uniformity related to HPRT-CCM (-3.29 ± 2.40; p < 0.0001), and demonstrated comparable intra-assay CVs (1.47 ± 0.74), albeit higher inter-assay CVs (5.38 ± 2.06; p = 0.01). Comparing EMBs from each 10 patients with dilated cardiomyopathy (DCM) and inflammatory cardiomyopathy (DCMi), T-PreAmp real-time RT-PCR analyses revealed differential regulation regarding 27 (30%) of the investigated 90 genes related to both HPRT-CCM and CDKN1B. Ct values of HPRT and CDKN1B did not differ in equal RNA amounts from explanted DCM and donor hearts.

Conclusion

In comparison to the SSRT-PreAmp, T-PreAmp enables a relatively simple workflow, and results in a robust PreAmp of multiple target genes (at least 92 gene assays as tested here) by a mean Ct improvement around 7 cycles, and in a lower inter-assay variance in RNA derived from EMBs. Preliminary analyses comparing EMBs from DCM and DCMi patients, revealing differential regulation regarding 30% of the investigated genes, confirm that T-PreAmp is a suitable tool to perform gene expression analyses in EMBs, expanding gene expression investigations with the limited RNA/cDNA amounts derived from EMBs. CDKN1B, in addition to its function as a reference gene for the calculation of PreAmp uniformity, might serve as a suitable housekeeping gene for real-time RT-PCR analyses of myocardial tissues.

Interferon-gamma induces chronic active myocarditis and cardiomyopathy in transgenic mice

Chronic heart failure is associated with an activation of the immune system characterized among other factors by the cardiac synthesis and serum expression of proinflammatory cytokines. There is unequivocal clinical and experimental evidence that the cytokine tumor necrosis factor-alpha is involved in the development of chronic heart failure, but a putative cardiotoxic potential of the proinflammatory cytokine interferon (IFN)-gamma remains primarily unknown. To investigate this issue we analyzed the cardiac phenotype of SAP-IFN-gamma transgenic mice, which constitutively express IFN-gamma in their livers and hence exhibit high circulating serum levels of this cytokine. SAP-IFN-gamma mice spontaneously developed chronic active myocarditis, characterized by the infiltration of not only CD4(+) and CD8(+) T cells but also Mac2(+) (galectin 3(+)) macrophages and CD11c(+) dendritic cells, eventually culminating in cardiomyopathy. Echocardiographic analyses exhibited a left ventricular dilation and impaired systolic function induced by IFN-gamma overexpression. IFN-gamma-mediated cardiotoxicity was associated with high-level cardiac transcription of the proinflammatory cytokines tumor necrosis factor-alpha and interleukin-12 and the macrophage-attracting chemokines MCP1 and MIP1-alpha. Myotoxic IFN-gamma effects could not be detected in smooth or striated muscle tissue, suggesting cardiomyocellular specificity of the toxic IFN-gamma effect. The precise mechanism of IFN-gamma cardiotoxicity remains to be elucidated.

Overview on chronic viral cardiomyopathy/chronic myocarditis

Myocarditis is most often induced by cardiotropic viruses and often resolves with minimal cardiac remodelling and without discernable prognostic impact. Acute myocarditis has a highly diverse clinical presentation (asymptomatic, infarct-like presentation, atrioventricular (AV)-block, atrial fibrillation, sudden death due to ventricular tachycardia, fulminant myocarditis with severely depressed contractility). Progression of myocarditis to its sequela, dilated cardiomyopathy (DCM), has been documented in 20% of cases and is pathogenically linked to chronic inflammation and viral persistence. Persistence of cardiotropic viruses (enterovirus, adenovirus) constitutes one of the predominant aetiological factors in DCM. Additionally, circulating autoantibodies to distinct cardiac autoantigens have been described in patients with DCM, providing evidence for autoimmune involvement. Since clinical complaints of myocarditis and DCM are unspecific, a positive effect of any specific therapy depends on an accurate biopsy-based diagnosis and characterization of the patients with histological, immunohistological and molecular biological methods (PCR), which have developed into sensitive tools for the detection of different viruses, active viral replication, and myocardial inflammation. The immunohistochemical characterization of infiltrates has supported a new era in the diagnosis of myocardial inflammation compared with the Dallas criteria, which has led to a new entity of secondary cardiomyopathies acknowledged by the WHO, the inflammatory cardiomyopathies (DCMi). Immunohistochemically quantified lymphocytes significantly better reflect troponin levels and correlate with findings by anti-myosin scintigraphy compared with the histological analysis. Furthermore, the orchestrated induction of endothelial cell adhesion molecules (CAMs) in 65% of DCM patients has confirmed that CAM induction is a prerequisite for lymphocytic infiltration in DCMi. The combination of these immunohistological with molecular biological diagnostic techniques of virus analysis allows a further classification of dilated cardiomyopathy by differentiating the disease entity in subgroups of virus-positive and virus-negative patients with or without cardiac inflammation. Further analysis of the predominant Th1-/Th2-immune response may provide additional prognostic information on the natural course of the disease. This differential analysis improves the clinical management of patients and is an indispensable prerequisite for the development of specific antiviral or immunomodulatory treatment strategies.

Frontiers in viral diagnostics

Dilated cardiomyopathy (DCM) is a fatal myocardial disease with an incidence of 40:100,000. In recent years, viral infection as a causative agent for myocarditis followed by DCM has become a main topic of research. On the one hand, the virus violates the myocardial integrity itself; on the other hand, the virus induces inadequate local humoral and cellular defense reaction resulting in cardiomyocyte death, fibrosis, and overall cardiac dysfunction. Classical virological approaches are no longer sufficient to detect and identify the virus in the heart. The possibility of endomyocardial biopsies, as well as the further development of new high-specific and sensitive molecular approaches including real-time PCR or sequencing, allows us to detect and to identify the patient- specific causal virus and to predict the progression of disease and hopefully, in the future, to develop virus-specific treatment strategies.

[Cardiomyopathies. I: classification of cardiomyopathies--dilated cardiomyopathy]

Cardiomyopathies are common causes of heart failure and sudden cardiac death. According to the WHO classification, "specific" cardiomyopathies are differentiated from "idiopathic" cardiomyopathies. Thus, this classification is primarily based on pathophysiological characteristics. The diagnostic spectrum in cardiomyopathies comprises the entire spectrum of non-invasive and invasive cardiological examination techniques. The exact verification of certain cardiomyopathies necessitates additionally investigations. For example, immunohistological and molecular biological investigations of endomyocardial biopsies may confirm inflammatory cardiomyopathy, which is often induced by viruses. Several studies have shown that specific immunomodulatory treatment options can halt the progressive course of the disease. Several gene mutations have been identified in genetic/familial dilated cardiomyopathy. First-degree relatives should be screened for early stages. Primary prevention of sudden cardiac death shows increasing superiority of the implantable defibrillator compared with pharmacological approaches (i.e. amiodarone).

Mycophenolate mofetil prevents the development of experimental autoimmune myocarditis

Experimental autoimmune myocarditis (EAM) is characterized by the appearance of multinucleated giant cells. EAM leads to severe myocardial damage and is a useful model of human giant cell myocarditis. We investigated whether mycophenolate mofetil (MMF), which is a potent immunosuppressant, prevents the development of myocarditis in a rat EAM model, and focused on the role of osteopontin (OPN) in the pathogenesis of this disorder. Adult Lewis rats were immunized with porcine cardiac myosin to establish EAM. The early MMF treatment completely prevented the development of EAM, and the late MMF treatment was also effective even against established EAM. Echocardiogram demonstrated that left ventricular function was also improved by the treatment with MMF. Real-time RT-PCR analysis showed that both early and late MMF treatments significantly inhibited myocarditis-induced OPN mRNA expression in the heart. Immunohistochemistry revealed that OPN expression was prominent in the myocardium on day 14, whereas expression was observed in the infiltrated macrophages on day 21. Mycophenolic acid (MPA) did inhibit agonist-induced OPN expression in cultured cardiomyocytes. These results show the therapeutic potential of MMF for autoimmune myocarditis and provide new insights into the pathogenesis of this disease.

Intramyocyte Detection of Epstein-Barr Virus Genome by Laser Capture Microdissection in Patients With Inflammatory Cardiomyopathy

Background— The causal role of Epstein-Barr virus (EBV) in inflammatory cardiomyopathy (IC) is still unclear, because this virus is present in latently infected circulating B lymphocytes in 90% of adults. Laser capture microdissection (LCM) has been applied on endomyocardial biopsy samples from patients with IC to assess the presence of EBV genome in separately dissected lymphocytes and myocytes.

Methods and Results— Among 142 patients with cardiac dilation and dysfunction and a histological and immunohistochemical diagnosis of myocarditis, 44 had a myocardial viral infection detected by polymerase chain reaction on frozen endomyocardial biopsy samples. In 9 of them, the virus detected was EBV. LCM was performed on 5-μm-thick paraffin sections of EBV-infected hearts. Lymphocytes and myocytes were microdissected and analyzed separately by polymerase chain reaction analysis on DNA extracted from the collected cells. Blood and myocardial samples from patients with positive and negative serology for EBV were used as controls. EBV genome was detected in myocytes but not in infiltrating lymphocytes of patients, nor in myocardial samples from controls. Despite full conventional antifailure therapy, a progressive cardiac dilation and dysfunction was documented in patients with EBV-related IC at a mean of 31±14 months of follow-up.

Conclusions— Intramyocyte detection of EBV can be obtained by LCM in up to 6.3% of patients with IC. This supports a cytopathic EBV role and suggests the opportunity for an antiviral/immunomodulatory therapy.