Recent studies have detected erythrovirus genomes in the hearts of cardiomyopathy and cardiac transplant patients. Assessment of the functional status of viruses may provide clinically important information beyond detection of the viral genomes. Here, we report transcriptional activation of cardiotropic erythrovirus to be associated with strongly altered myocardial gene expression in a distinct subgroup of cardiomyopathy patients. Endomyocardial biopsies (EMBs) from 415 consecutive cardiac erythrovirus (B19V)-positive patients with clinically suspected cardiomyopathy were screened for virus-encoded VP1/VP2 mRNA indicating transcriptional activation of the virus, and correlated with cardiac host gene expression patterns in transcriptionally active versus latent infections, and in virus-free control hearts. Transcriptional activity was detected in baseline biopsies of only 66/415 patients (15.9 %) harbouring erythrovirus. At the molecular level, significant differences between cardiac B19V-positive patients with transcriptionally active versus latent virus were revealed by expression profiling of EMBs. Importantly, latent B19V infection was indistinguishable from controls. Genes involved encode proteins of antiviral immune response, B19V receptor complex, and mitochondrial energy metabolism. Thus, functional mapping of erythrovirus allows definition of a subgroup of B19V-infected cardiomyopathy patients characterized by virus-encoded VP1/VP2 transcripts and anomalous host myocardial transcriptomes. Cardiac B19V reactivation from latency, as reported here for the first time, is a key factor required for erythrovirus to induce altered cardiac gene expression in a subgroup of cardiomyopathy patients. Virus genome detection is insufficient to assess pathogenic potential, but additional transcriptional mapping should be incorporated into future pathogenetic and therapeutic studies both in cardiology and transplantation medicine.

Aims To quantify and functionally characterize the intramyocardial T‐cells in endomyocardial biopsies (EMBs) from patients presenting with acute myocarditis (AMC) and dilated cardiomyopathy (DCM). Methods and results Expression of genes characterizing Th1 [interferon (IFN)γ, Tbet‐1, Eomesodermin, interleukin (IL)‐27], Th2 (IL‐4, IL‐5, GATA3), Th17 (IL‐17), regulatory [regulatory T‐cells (Treg); FoxP3, TGFβ, IL‐10], anergic (GRAIL), and cytotoxic T‐cells (CTLs: Perforin, Granulysin, Granzyme A), as well as of functional T‐cell receptor Vbeta (TRBV) families were investigated in EMBs from AMC patients (n= 58) and DCM patients (n= 34) by pre‐amplified real‐time reverse transcription‐polymerase chain reaction. These data were compared with EMBs from n= 19 controls. Expression of CD3d, CD3z, and TRBC (T‐cell receptor beta constant region) were associated with the immunohistological diagnosis of inflammatory cardiomyopathy (DCMi). In EMBs from DCM patients with increased CD3d expression, significantly increased markers of Th1 (IFNγ, T‐bet, Eomesodermin), regulatory T‐cells (Treg; FoxP3, TGFβ), and cytotoxic T‐cells (CTLs: Perforin, Granulysin, Granzyme A) were present, while no differential polarization of T‐cells was found in EMBs form AMC patients. A differential dominance of distinct functional TRBV families was associated with different cardiotropic viruses: TRBV 11 and 24 with Parvovirus B19; TRBV4, 10 and 28 with human herpes virus type 6; and TRBV14 for Coxsackie virus, respectively. Conclusions The T‐cell infiltrates in human DCMi are characterized by differential expression of functional T‐cell markers indicating Th1, Treg, and CTLs, while no major role could be confirmed for Th17. The virus‐associated differential TRBV dominance suggests an antiviral specificity of virus‐induced T‐cell responses in human DCMi.

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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).

Organic cation transporters (OCT1-3 and OCTN1/2) facilitate cardiac uptake of endogenous compounds and numerous drugs. Genetic variants of OCTN2, for example, reduce uptake of carnitine, leading to heart failure. Whether expression and function of OCTs and OCTNs are altered by disease has not been explored in detail. We therefore studied cardiac expression, heart failure-dependent regulation, and affinity to cardiovascular drugs of these transporters. Cardiac transporter mRNA levels were OCTN2>OCT3>OCTN1>OCT1 (OCT2 was not detected). Proteins were localized in vascular structures (OCT3/OCTN2/OCTN1) and cardiomyocytes (OCT1/OCTN1). Functional studies revealed a specific drug-interaction profile with pronounced inhibition of OCT1 function, for example, carvedilol [half maximal inhibitory concentration (IC₅₀), 1.4 μmol/L], diltiazem (IC₅₀, 1.7 μmol/L), or propafenone (IC₅₀, 1.0 μmol/L). With use of the cardiomyopathy model of coxsackievirus-infected mice, Octn2mRNA expression was significantly reduced (56% of controls, 8 days after infection). Accordingly, in endomyocardial biopsy specimens OCTN2 expression was significantly reduced in patients with dilated cardiomyopathy, whereas the expression of OCT1-3 and OCTN1 was not affected. For OCTN2 we observed a significant correlation between expression and left ventricular ejection fraction (r = 0.53, P < 0.0001) and the presence of cardiac CD3⁺ T cells (r = -0.45, P < 0.05), respectively. OCT1, OCT3, OCTN1, and OCTN2 are expressed in the human heart and interact with cardiovascular drugs. OCTN2 expression is selectively reduced in dilated cardiomyopathy patients and predicts the impairment of cardiac function.