Heart Transplantation in Systemic Sclerosis: New Impulses for Conventional Scleroderma Transplantation Regimen and Scleroderma Diagnostic Monitoring: 2 Case Reports

BACKGROUND

Although low (but increasing) rates of lung/lung-heart transplantations of scleroderma (systemic sclerosis [SSc]) patients have been reported, exclusive heart transplantation is a rare approach for treatment of heart failure due to SSc.

CASES

We report on 2 cases of SSc patients receiving a heart transplantation (HTx) due to severe and progressive right heart failure without pulmonary artery hypertension. One patient received a hepatitis C virus (HCV)-positive donor heart and recovered excellently from viral transmission after administration of a direct-acting antiviral (DAA) regimen. This is the first published case of an SSc patient who underwent HTx using an HCV-positive donor heart. The clinical course of both patients was monitored by different serum SSc biomarkers. Only xylosyltransferase activity proved to be a promising biomarker for disease stage determination and therapeutic monitoring, precisely reflecting fibrotic remodeling and successful organ recovery.

CONCLUSIONS

Successful implementation of the 2 cases described here demonstrates that HTx is a safe and effective therapeutic option for defined SSc sub-patient groups despite the progressive character of the underlying disease. In the future, xylosyltransferase activity might be conducive to simplify the identification of patients with low systemic involvement but a strong indication for single heart transplantation. Finally, we demonstrate that treatment of HCV viral transmission from HCV-positive donor to organ recipient using DAA gives us new opportunities to consider HCV-positive donor organs for HTx and might reveal new possibilities to ease the lack of donor organs.

Myocardial expression of the anaphylatoxin receptor C3aR is associated with cardiac inflammation and prognosis in patients with non-ischaemic heart failure

Aim

The aim of this study is to analyse the prognostic value of complement anaphylatoxin receptors in patients with non‐ischaemic cardiomyopathy undergoing endomyocardial biopsy.

Methods and results

In 102 patients (72.5% male patients, median age 54 years) with non‐ischaemic cardiomyopathy, myocardial expression of C3aR was assessed among other parameters. The primary study endpoint was a composite of death, heart transplantation, heart failure‐related re‐hospitalization, and deterioration of left ventricular ejection fraction within a mean follow‐up of 11.9 months. The number of cells, which stained positive for C3aR, was significantly increased in patients with inflammatory compared with non‐inflammatory cardiomyopathy (1.75 ± 0.31 cells in inflammatory cardiomyopathy vs. 0.94 ± 0.26 in non‐inflammatory cardiomyopathy, P = 0.049). Subsequently, positive expression for C3aR was judged based on a semi‐quantitative scoring system. Significantly, more patients with positive MHCII and CD68 expression showed an increased number of C3aR‐positive cells. C3aR expression based on this score was more pronounced in patients with human herpesvirus 6 viral genome detection. Kaplan–Meier curves illustrate that the C3aR‐negative group reached the primary endpoint significantly more often (mean follow‐up 11.9 months, log rank 5.963, P = 0.015). Lack of C3aR expression was a strong independent predictor for the primary endpoint in Cox regression analysis [hazard ratio 0.46 (0.26–0.82, P = 0.009)].

Conclusions

C3aR‐positive cells are found more often in patients with inflammatory cardiomyopathy. The relevance of C3aR‐positive cells in patients with non‐ischaemic cardiomyopathy should be further evaluated as potential predictors or modulators of adverse cardiac remodelling, the substrate of progressive heart failure.

α-Galactosidase A Genotype N215S Induces a Specific Cardiac Variant of Fabry Disease

BACKGROUND

Hypertrophic cardiomyopathy is the most common type of cardiomyopathy, but many patients lack sarcomeric/myofilament mutations. We studied whether cardio-specific α-galactosidase A gene variants are misinterpreted as hypertrophic cardiomyopathy because of the lack of extracardiac organ involvement.

METHODS AND RESULTS

All subjects who tested positive for the N215S genotype (n=26, 13 females, mean age 49±17 [range, 14-74] years) were characterized in this prospective monocentric longitudinal cohort study to determine genotype-specific clinical characteristics of the N215S (c.644A>G [p.Asn215Ser]) α-galactosidase A gene variant. All subjects were initially referred with suspicion of genetically determined hypertrophic cardiomyopathy. Cardiac hypertrophy (interventricular septum, 12±4 [7-23] mm; left ventricular posterior wall, 11±4 [7-21] mm; left ventricular mass, 86±41 [46-195] g/m²) was progressive, systolic function mainly preserved (cardiac index 2.8±0.6 [1.9-3.9] L/min per m²), and diastolic function mildly abnormal. Cardiac magnetic resonance imaging revealed replacement fibrosis in loco typico (18/26, 69%), particularly in subjects >50 years. Elderly subjects had advanced heart failure, and 6 (23%) were suggested for implantable cardioverter-defibrillator therapy. Leukocyte α-galactosidase A enzyme activity was mildly reduced in 19 subjects and lyso-globotriaosylceramide slightly elevated (median, 4.9; interquartile range, 1.3-9.1 ng/mL). Neurological and renal impairments (serum creatinine, 0.87±0.20; median, 0.80; interquartile range, 0.70-1.01 mg/dL; glomerular filtration rate, 102±23; median, 106; interquartile range, 84-113 mL/min) were discreet. Only 2 subjects developed clinically relevant proteinuria.

CONCLUSIONS

α-Galactosidase A genotype N215S does not lead to the development of a classical Fabry phenotype but induces a specific cardiac variant of Fabry disease mimicking nonobstructive hypertrophic cardiomyopathy. The lack of prominent noncardiac impairment leads to a significant delay in diagnosis and Fabry-specific therapy.

Parvovirus B19-induced vascular damage in the heart is associated with elevated circulating endothelial microparticles

Background

Diagnosis of viral myocarditis is difficult by clinical criteria but facilitated by detection of inflammation and viral genomes in endomyocardial biopsies. Parvovirus B19 (B19V) targets endothelial cells where viral nucleic acid is exclusively detected in the heart. Microparticles (MPs) are released after cell damage or activation of specific cells. We aimed to investigate whether circulating endothelial MPs (EMPs) in human and experimental models of myocarditis are associated with B19V myocarditis.

Methods

MPs were investigated in patients with myocarditis (n = 54), divided into two groups: B19V+ (n = 23) and B19V- (n = 31) and compared with healthy controls (HCTR, n = 25). MPs were also investigated in B19V transgenic mice (B19V-NS1+) and mice infected with coxsackievirus B3 (CVB3). MPs were analyzed with fluorescent activated cell sorting (FACS).

Results

In human samples, EMP subpopulation patterns were significantly different in B19V+ compared to B19V- and HCTR (p<0.001), with an increase of apoptotic but not activated EMPs. Other MPs such as platelet- (PMPs) leukocyte-(LMPs) and monocyte-derived MPs (MMPs) showed less specific patterns. Significantly different levels of EMPs were observed in transgenic B19V-NS1+ mice compared with CVB3-infected mice (p<0.001).

Conclusion

EMP subpopulations are different in B19V+ myocarditis in humans and transgenic B19V mice reflecting vascular damage. EMP profiles might permit differentiation between endothelial-cell-mediated diseases like myocardial B19V infection and other causes of myocarditis.

CMR-Derived Extracellular Volume Fraction as a Marker for Myocardial Fibrosis: The Importance of Coexisting Myocardial Inflammation

OBJECTIVES

The aim of the present study was to evaluate whether extracellular volume fraction (ECV) can reliably inform on the extent of diffuse fibrosis in the simultaneous presence of myocardial inflammation, which has not been verified to date.

BACKGROUND

Diffuse myocardial fibrosis is associated with unfavorable outcome in patients with cardiomyopathy, and is of prognostic relevance. Assessment of ECV bears promise for being a noninvasive surrogate parameter, but it may be altered by other pathologies.

METHODS

In this prospective study, 107 consecutive patients with clinical suspicion of inflammatory cardiomyopathy were included. All patients underwent left ventricular (LV) endomyocardial biopsy (EMB) and cardiac magnetic resonance imaging on a 1.5-T scanner. T1 mapping was obtained with the modified Look-Locker inversion recovery sequence, and ECV was calculated.

RESULTS

Myocardial inflammation was present in 66 patients. Patients with and without inflammation were of similar age and had comparable LV ejection fraction (37 ± 17% vs. 36 ± 18%; p = 0.9) and symptom duration (median 14 days [interquartile range: 5 to 36 days] vs. median 14 days [interquartile range: 7 to 30 days]; p = 0.73). Although LV collagen volume percentage was comparable between groups (inflammation 12.3 ± 17.8% vs. noninflammation 11.4 ± 7.9%; p = 0.577), ECV was significantly higher in patients with inflammation (0.37 ± 0.06%) than in those without inflammation (0.33 ± 0.08%; p = 0.02). Importantly, ECV adequately estimated the degree of LV fibrosis percentage only in patients without inflammation (r = 0.72; p < 0.0001) and not in those with inflammation (r = 0.24; p = 0.06).

CONCLUSIONS

These findings prove the theoretical concept of ECV as an estimate for diffuse myocardial fibrosis, but only in the absence of significant myocardial inflammation. Assuming that various degrees of myocardial inflammation and fibrosis coexist in such a scenario, the measured ECV will reflect a sum of these different pathologies but will not inform solely on the extent of diffuse fibrosis.

In vivo T2* weighted MRI visualizes cardiac lesions in murine models of acute and chronic viral myocarditis

Objective

Acute and chronic forms of myocarditis are mainly induced by virus infections. As a consequence of myocardial damage and inflammation dilated cardiomyopathy and chronic heart failure may develop. The gold standard for the diagnosis of myocarditis is endomyocardial biopsies which are required to determine the etiopathogenesis of cardiac inflammatory processes. However, new non-invasive MRI techniques hold great potential in visualizing cardiac non-ischemic inflammatory lesions at high spatial resolution, which could improve the investigation of the pathophysiology of viral myocarditis.

Results

Here we present the discovery of a novel endogenous T2* MRI contrast of myocardial lesions in murine models of acute and chronic CVB3 myocarditis. The evaluation of infected hearts ex vivo and in vivo by 3D T2w and T2*w MRI allowed direct localization of virus-induced myocardial lesions without any MRI tracer or contrast agent. T2*w weighted MRI is able to detect both small cardiac lesions of acute myocarditis and larger necrotic areas at later stages of chronic myocarditis, which was confirmed by spatial correlation of MRI hypointensity in myocardium with myocardial lesions histologically. Additional in vivo and ex vivo MRI analysis proved that the contrast mechanism was due to a strong paramagnetic tissue alteration in the vicinity of myocardial lesions, effectively pointing towards iron deposits as the primary contributor of contrast. The evaluation of the biological origin of the MR contrast by specific histological staining and transmission electron microscopy revealed that impaired iron metabolism primarily in mitochondria caused iron deposits within necrotic myocytes, which induces strong magnetic susceptibility in myocardial lesions and results in strong T2* contrast.

Conclusion

This T2*w MRI technique provides a fast and sensitive diagnostic tool to determine the patterns and the severity of acute and chronic enteroviral myocarditis and the precise localization of tissue damage free of MR contrast agents.

Plasma and Cardiac Galectin-3 in Patients With Heart Failure Reflects Both Inflammation and Fibrosis

Background—

Galectin (Gal)-3 is a β-galactoside-binding lectin and currently intensely studied as a biomarker in heart failure. Gal-3 also exerts proinflammatory effects, at least in extracardiac tissues. Objective of this study was to characterize the relationship of plasma and myocardial Gal-3 levels with cardiac fibrosis and inflammation in patients with nonischemic dilated cardiomyopathy and inflammatory cardiomyopathy (iCMP).

Methods and Results—

Endomyocardial biopsies and blood samples were obtained from patients with newly diagnosed cardiomyopathy and clinical suspicion of myocarditis. According to histopathologic findings, patients were classified as having dilated cardiomyopathy (n=40) or iCMP (n=75). Cardiac fibrosis was assessed histologically on endomyocardial biopsy sections. In patients with iCMP, myocardial Gal-3 expression significantly correlated with inflammatory cell count on endomyocardial biopsy ( r =0.56; P <0.05). In contrast, an inverse association was observed between myocardial Gal-3 expression and cardiac fibrosis in patients with iCMP ( r =−0.59; P <0.05). In patients with dilated cardiomyopathy, myocardial Gal-3 expression correlated with cardiac fibrosis on left ventricular biopsy ( P =0.63; P <0.01). Of note, in both groups, plasma Gal-3 levels did not correlate with myocardial Gal-3 levels or left ventricular fibrosis, whereas a positive correlation between plasma Gal-3 levels and inflammatory cell count on endomyocardial biopsy was observed in patients with iCMP.

Conclusions—

The present study suggests that myocardial Gal-3 can be considered as a possible marker for both cardiac inflammation and fibrosis, depending on the pathogenesis of heart failure. However, circulating concentrations of Gal-3 do not seem to reflect endomyocardial Gal-3 levels or cardiac fibrosis.

Cardiovascular magnetic resonance patterns of biopsy proven cardiac involvement in systemic sclerosis

BACKGROUND

To determine morphological and functional cardiovascular magnetic resonance (CMR) patterns in histopathologically confirmed myocardial involvement in patients with systemic sclerosis (SSc).

METHODS

Twenty patients (6 females; mean age 41 ± 11 years) with histopathologically proven cardiac involvement in SSc in the years 2008-2016 were retrospectively evaluated. Morphological, functional and late gadolinium enhancement (LGE) images were acquired in standard angulations at 1.5 T CMR. Pathologies were categorized: 1) Pericardial effusion; 2) pathologic left (LV) or right ventricular (RV) contractility (hypokinesia, dyssynchrony, and diastolic restriction); 3) reduced left (LV-EF) and right ventricular ejection fraction (RV-EF); 4) fibrosis and/or inflammation (positive LGE); 5) RV dilatation. 95 % confidence intervals (CI) were calculated for appearance of pathologic EF and RV dilatation.

RESULTS

Seven patients (35 %) had positive CMR findings in three categories, 9 patients (45 %) in four categories and 4 patients (20 %) in five categories. The distribution of pathologic findings was: minimal pericardial effusion in 7 patients (35 %), moderate pericardial effusion >5 mm in nine patients (45 %); abnormal LV or RV contractility in 19 patients (95 %), reduced LV or RV function in 14 patients (70 %; 95 % CI: 51-88 %), pathologic LGE in all patients, RV dilatation in 6 patients (30 %; 95 % CI: 15-54 %).

CONCLUSIONS

CMR diagnosis of myocardial involvement in SSc requires increased attention to subtle findings. Pathologic findings in at least three of five categories indicate myocardial involvement in SSc.

Endomyocardial biopsy in patients with cardiomyopathy of unknown origin: does specialized center experience apply to a tertiary care hospital?

BACKGROUND

In patients with cardiomyopathy of unknown origin, endomyocardial biopsy provides the possibility of improved diagnosis and tailored treatment. Specific guidance has been developed based on cardiovascular centre of excellence experience but it is unknown if the benefits also extend into the tertiary care hospital setting.

METHODS

Endomyocardial biopsies was performed in patients with cardiomyopathy of unknown origin. The outcomes were mirrored against the current ESC recommendations.

RESULTS

A total of 57 patients with cardiomyopathy of unknown origin underwent endomyocardial biopsy with a mean age of 54 years and 28 % being women. In 17 patients (30 %), viruses were detected in the biopsy material, in 6 patients (11 %) cardiac amyloidosis was found of which 3 had also a positive test for viruses. The overall mortality rate was 18 % in the mean follow up period of 30 months, with a rate of 24 % in those with virus detection (mean FU 24 months) and 15 % in those without virus detection (mean FU 31 months. Death rates were 83 % in patients with cardiac amyloidosis (mean FU 10 months).

CONCLUSION

We conclude that, limited by uncertainty stemming from the small number of included patients, endomyocardial biopsy may not prove to have a clinical impact on treatment decisions and outcomes in a tertiary care hospital setting. We consider cardiac amyloidosis to be an exception, since the mortality rate with or without concomitant virus load was extremely high.

A new monoclonal antibody (Cox mAB 31A2) detects VP1 protein of coxsackievirus B3 with high sensitivity and specificity

Human enteroviruses, e.g. coxsackieviruses, induce a variety of severe acute and chronic forms of disease, including myocarditis, meningitis and diabetes mellitus type 1. To visualize enterovirus infection with a diagnostic intent, many studies have applied a commercially available antibody (anti-CVB5 VP1, clone 5-D8/1, Dako, Hamburg, Germany) that identifies VP1 of different enteroviral serotypes. Many antibodies, however, have been found to bind non-specifically to proteins of cardiomyocytes and in the interstitial space, resulting in non-specific staining in immunohistochemistry. In this paper we show that the anti-CVB5 VP1 antibody, recognizing VP1 of coxsackieviruses and widely used in diagnostics and research, shows strong cross-reactivity with cellular proteins in the heart (and pancreas) of humans and mice, which calls for a more specific antibody to be used for diagnostic purposes. We observed by Western blot analyses of lysates from human heart tissue samples and HeLa cells two cross-reactive bands when using clone 5-D8/1. Peptide mass fingerprinting (MALDI-TOF) identified these proteins as creatine kinase (B-type) and tubulin, confirming that this mAb detects cellular proteins in addition to viral VP1. In order to overcome the problems of false positive VP1 staining we generated a new highly specific and sensitive monoclonal antibody (Cox mAB 31A2) that recognizes VP1 from CVB3. The new antibody was characterized and was found to function well in immunohistochemistry, immunofluorescence staining, Western blotting, ELISA and FACS analyses.

Comprehensive Cardiac Magnetic Resonance Imaging in Patients With Suspected Myocarditis: The MyoRacer-Trial

BACKGROUND

Data suggest that T1 and T2 mapping have excellent diagnostic accuracy in patients with suspected myocarditis. However, the true diagnostic performance of comprehensive cardiac magnetic resonance (CMR) mapping versus endomyocardial biopsy (EMB) has not been determined.

OBJECTIVES

This study assessed the performance of CMR imaging, including T1 and T2 mapping, compared with EMB in an unselected, consecutive patient cohort with suspected myocarditis. It also examined the potential role of CMR field strength by comparing 1.5-T versus 3.0-T imaging.

METHODS

Patients underwent biventricular EMB, cardiac catheterization (for exclusion of coronary artery disease), and CMR imaging on 1.5- and 3-T scanners. The CMR protocol included current standard Lake Louise criteria (LLC) for myocarditis as well as native T1, calculation of extracellular volume fraction (ECV), and T2 mapping (only on 1.5-T). Patients were divided into 2 groups according to symptom duration (acute: ≤14 days vs. chronic: >14 days).

RESULTS

A total of 129 patients underwent 1.5-T imaging. In patients with acute symptoms, native T1 yielded the best diagnostic performance as defined by the area under the curve (AUC) of receiver-operating curves (0.82) followed by T2 (0.81), ECV (0.75), and LLC (0.56). In patients with chronic symptoms, only T2 mapping yielded an acceptable AUC (0.77). On 3.0-T, AUCs of native T1, ECV, and LLC were comparable to 1.5-T with no significant differences.

CONCLUSIONS

In patients with acute symptoms, mapping techniques provide a useful tool for confirming or rejecting the diagnosis of myocarditis and are superior to the LLC. However, only T2 mapping has acceptable diagnostic performance in patients with chronic symptoms. (Magnetic Resonance Imaging in Myocarditis [MyoRacer]; NCT02177630).

Changes of myocardial gene expression and protein composition in patients with dilated cardiomyopathy after immunoadsorption with subsequent immunoglobulin substitution

Immunoadsorption with subsequent immunoglobulin substitution (IA/IgG) represents a therapeutic approach for patients with dilated cardiomyopathy (DCM). Here, we studied which molecular cardiac alterations are initiated after this treatment. Transcription profiling of endomyocardial biopsies with Affymetrix whole genome arrays was performed on 33 paired samples of DCM patients collected before and 6 months after IA/IgG. Therapy-related effects on myocardial protein levels were analysed by label-free proteome profiling for a subset of 23 DCM patients. Data were analysed regarding therapy-associated differences in gene expression and protein levels by comparing responders (defined by improvement of left ventricular ejection fraction ≥20 % relative and ≥5 % absolute) and non-responders. Responders to IA/IgG showed a decrease in serum N-terminal proBNP levels in comparison with baseline which was accompanied by a decreased expression of heart failure markers, such as angiotensin converting enzyme 2 or periostin. However, despite clinical improvement even in responders, IA/IgG did not trigger general inversion of DCM-associated molecular alterations in myocardial tissue. Transcriptome profiling revealed reduced gene expression for connective tissue growth factor, fibronectin, and collagen type I in responders. In contrast, in non-responders after IA/IgG, fibrosis-associated genes and proteins showed elevated levels, whereas values were reduced or maintained in responders. Thus, improvement of LV function after IA/IgG seems to be related to a reduced gene expression of heart failure markers and pro-fibrotic molecules as well as reduced fibrosis progression.

Endomyocardial miR-133a levels correlate with myocardial inflammation, improved left ventricular function, and clinical outcome in patients with inflammatory cardiomyopathy

AIMS

Inflammatory heart disease represents an important cause of chronic dilated cardiomyopathy (DCM). Predicting the clinical course of patients with inflammatory cardiomyopathy (iCMP) is difficult, and the prognostic value of current biological markers remains controversial. We tested whether expression of selected microRNAs in endomyocardial biopsies (EMBs) is related to LV functional recovery and clinical events in iCMP patients.

METHODS AND RESULTS

EMBs were obtained from patients with iCMP (n = 76) and non-inflammatory DCM (n = 22). A set of six microRNAs implicated in inflammation (miR-155 and miR-146b), heart failure (miR-21 and miR-133a), and endothelial cell (miR-126) and skeletal muscle function (miR-206) was pre-defined. Endomyocardial expression of miR-155 and miR-133a, as quantified by reverse transcription-PCR (RT-PCR), was up-regulated in patients with iCMP as compared with patients with DCM. Levels of miR-133a (R = 0.73, P < 0.01) and miR-155 (R = 0.63, P < 0.01) correlated with inflammatory cell count on EMBs from patients with iCMP. Patients with iCMP and preserved LV function at study entry demonstrated higher expression of miR-133a than patients with reduced LV function. Also, increased expression of miR-133a was associated with less fibrosis and myocyte necrosis on EMB, and LV functional recovery during a mean follow-up of 3.1 years. Importantly, patients with iCMP and miR-133a levels in the upper tertile showed longer survival free of death, malignant arrhythmias, and hospitalizations for heart failure.

CONCLUSION

The present study demonstrates that miR-133a levels correlate with macrophage infiltration, cardiac injury, improved LV function, and clinical outcome in patients with iCMP. miR-133a may serve as a potential novel biomarker and therapeutic target in human iCMP.

Lyme carditis--diagnosis, treatment and prognosis

BACKGROUND

There are 60,000 to 100,000 new cases of borreliosis in Germany each year. This infectious disease most commonly affects the skin, joints, and nervous system. Lyme carditis is a rare manifestation with potentially lethal complications.

METHODS

This review is based on selected publications on the clinical manifestations, diagnosis, and treatment of Lyme carditis, and on the authors' scientific and clinical experience.

RESULTS

Lyme carditis is seen in 4% to 10% of all patients with Lyme borreliosis. Whenever the clinical suspicion of Lyme carditis arises, an ECG is mandatory for the detection or exclusion of an atrioventricular conduction block. Patients with a PQ interval longer than 300 ms need continuous ECG monitoring. 90% of patients with Lyme carditis develop cardiac conduction abnormalities, and 60% develop signs of perimyocarditis. Borrelia serology (ELISA) may still be negative in the early phase of the condition, but is always positive in later phases. Cardiac MRI can be used to confirm the diagnosis and to monitor the patient's subsequent course. The treatment of choice is with antibiotics, preferably ceftriaxone. The cardiac conduction disturbances are usually reversible, and the implantation of a permanent pacemaker is only exceptionally necessary. There is no clear evidence at present for an association between borreliosis and the later development of a dilated cardiomyopathy. When Lyme carditis is treated according to the current guidelines, its prognosis is highly favorable.

CONCLUSION

Lyme carditis is among the rarer manifestations of Lyme borreliosis but must nevertheless be considered prominently in differential diagnosis because of the potentially severe cardiac arrhythmias that it can cause.

Myocardial expression profiles of candidate molecules in patients with arrhythmogenic right ventricular cardiomyopathy/dysplasia compared to those with dilated cardiomyopathy and healthy controls

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) is mainly an autosomal dominant disease characterized by fibrofatty infiltration of the right ventricle, leading to ventricular arrhythmias. Mutations in desmosomal proteins can be identified in about half of the patients. The pathogenic mechanisms leading to disease expression remain unclear.

OBJECTIVE

The purpose of this study was to investigate myocardial expression profiles of candidate molecules involved in the pathogenesis of ARVC/D.

METHODS

Myocardial messenger RNA (mRNA) expression of 62 junctional molecules, 5 cardiac ion channel molecules, 8 structural molecules, 4 apoptotic molecules, and 6 adipogenic molecules was studied. The averaged expression of candidate mRNAs was compared between ARVC/D samples (n = 10), nonfamilial dilated cardiomyopathy (DCM) samples (n = 10), and healthy control samples (n = 8). Immunohistochemistry and quantitative protein expression analysis were performed. Genetic analysis using next generation sequencing was performed in all patients with ARVC/D.

RESULTS

Following mRNA levels were significantly increased in patients with ARVC/D compared to those with DCM and healthy controls: phospholamban (P ≤ .001 vs DCM; P ≤ .001 vs controls), healthy tumor protein 53 apoptosis effector (P = .001 vs DCM; P ≤ .001 vs controls), and carnitine palmitoyltransferase 1β (P ≤ .001 vs DCM; P = 0.008 vs controls). Plakophillin-2 (PKP-2) mRNA was downregulated in patients with ARVC/D with PKP-2 mutations compared with patients with ARVC/D without PKP-2 mutations (P = .04). Immunohistochemistry revealed significantly increased protein expression of phospholamban, tumor protein 53 apoptosis effector, and carnitine palmitoyltransferase 1β in patients with ARVC/D and decreased PKP-2 expression in patients with ARVC/D carrying a PKP-2 mutation.

CONCLUSION

Changes in the expression profiles of sarcolemmal calcium channel regulation, apoptosis, and adipogenesis suggest that these molecular pathways may play a critical role in the pathogenesis of ARVC/D, independent of the underlying genetic mutations.

Ultrastructural morphometric findings of cardiomyocytes in patients with impaired ventricular function--a comparative clinicopathological study

AIM

The present study aims to analyze the differences in ultrastructural changes between right ventricular myocardium in clinically determined grades of heart failure (HF) [New York Heart Association (NYHA) classes I-IV] and their value in the routine diagnostic setting.

METHODS

We investigated consecutive right ventricular endomyocardial biopsies of 12 patients presenting with HF (49±11.2years; male=10) by light microscopy and ultrastructural morphometric analysis. The patients were divided into four groups according to their NYHA classes (NYHA I: n=1, II: n=2, III: n=8, IV: n=1). We used a stereological point counting method on electron micrographs to determine the volume, surface, and numerical density of cardiomyocyte myofibrils; z-lines; mitochondria; and cristae as required. Further, secondary parameters were calculated.

RESULTS

Myofibrillar parameters increased between NYHA class I and II (P<.01), which matched with more pronounced cardiomyocyte hypertrophy on the light microscopic level. In NYHA classes III and IV, the myofibrillar parameters dropped, while parameters concerning the mitochondria and their cristae rose (P<.01). This resulted in an elevated mitochondria to myofibril ratio (P<.05) and correlated with histologically evident atrophic cardiomyocytes, perinuclear loss of myofibrils and dot-like perinuclear staining positive on peroxide acid shift.

CONCLUSION

In this present study, right ventricular myocardial ultrastructure differed between patients diagnosed with HF of different degrees in distinct subcellular changes. These findings suggest that ultrastructural analysis, while correlated with histopathological features, adds to the diagnosis in the routine diagnostic setting, specifically in lower NYHA grades, in which only minor changes are observed histologically.

Performance of t1 and t2 mapping cardiovascular magnetic resonance to detect active myocarditis in patients with recent-onset heart failure

BACKGROUND

This study evaluated the performance of novel quantitative T1 and T2 mapping cardiovascular magnetic resonance (CMR) techniques to identify active myocarditis in patients with recent-onset heart failure.

METHODS AND RESULTS

Thirty-one consecutive patients with recent-onset heart failure, reduced left ventricular function and clinically suspected myocarditis underwent endomyocardial biopsy and CMR at 1.5 Tesla. The CMR protocol included standard Lake-Louise parameters as well as T1 mapping using a modified Look-Locker inversion recovery sequence and T2 mapping using a hybrid gradient and spin-echo sequence. Short-axis maps were generated using an OsiriX plug-in to calculate global myocardial T1, T2, and extracellular volume fraction. Active myocarditis was defined by ongoing inflammation on endomyocardial biopsy. Endomyocardial biopsy revealed active myocarditis in 16 (52%) of 31 patients. Neither clinical characteristics, standard Lake-Louise CMR parameters, global myocardial T1 nor extracellular volume fraction differed significantly between patients with and without active myocarditis. However, median global myocardial T2 was significantly higher in patients with active myocarditis (65 ms [Q1-Q3, 61-70 ms]) than in patients without active myocarditis (59 ms [Q1-Q3, 55-64 ms]; P<0.01). A cutoff value for global myocardial T2 of ≥60 ms provided a sensitivity, specificity, accuracy, negative and positive predictive value of 94% (70%-100%), 60% (32%-84%), 77% (60%-89%), 90% (56%-100%), and 71% (48%-89%) for active myocarditis, respectively.

CONCLUSIONS

T2 mapping seems to be superior when compared with standard CMR parameters, global myocardial T1, and extracellular volume fraction values for assessing the activity of myocarditis in patients with recent-onset heart failure and reduced left ventricular function.

Focal myocardial fibrosis assessed by late gadolinium enhancement cardiovascular magnetic resonance in children and adolescents with dilated cardiomyopathy

BACKGROUND

Different patterns of late gadolinium enhancement (LGE) including mid-wall fibrosis using cardiovascular magnetic resonance (CMR) have been reported in adult patients presenting with non-ischemic dilated cardiomyopathy (DCM). In these studies, LGE was associated with pronounced LV remodelling and predicted adverse cardiac outcomes. Accordingly, the purpose of our study was to determine the presence and patterns of LGE in children and adolescents with DCM.

METHODS

Patients <18 years of age presenting with severe congestive heart failure who were admitted for evaluation of heart transplantation at our centre underwent CMR examination which consisted of ventricular functional analysis and assessment of LGE for detection of myocardial fibrosis. Ischemic DCM was excluded by coronary angiography, and right ventricular endomyocardial biopsies ruled out acute myocarditis.

RESULTS

Thirty-one patients (mean age 2.1 ± 4.2 years) with severe LV dilatation (mean indexed LVEDV 136 ± 48 ml/m(2)) and LV dysfunction (mean LV-EF 23 ± 8%) were examined. LGE was detected in 5 of the 31 patients (16%) appearing in various patterns characterized as mid-wall (n = 1), focal patchy (n = 1), RV insertion site (n = 1) and transmural (n = 2). Based on histopathological analysis, 4 of the 5 LGE positive patients had lymphocytic myocarditis, whereas one patient was diagnosed with idiopathic DCM.

CONCLUSIONS

In children and adolescents with DCM, focal histologically proven myocardial fibrosis is rarely detected by LGE CMR despite marked LV dilatation and severely depressed LV function. LGE occurred in various patterns and mostly in patients with inflammatory cardiomyopathy. It remains unclear whether myocardial fibrosis in childhood DCM reflects different endogenous repair mechanisms that enable favourable reverse remodelling. Larger trials are needed to assess the prognostic implications of LGE in childhood DCM.

Clinical and histopathological features of patients with systemic sclerosis undergoing endomyocardial biopsy

Background

Cardiac involvement in systemic sclerosis (SSc) is associated with a variable phenotype including heart failure, arrhythmias and pulmonary hypertension. The aim of the present study was to evaluate clinical characteristics, histopathological findings and outcome of patients with SSc and a clinical phenotype suggesting cardiac involvement.

Methods and Results

25 patients with SSc and clinical signs of cardiac involvement were included between June 2007 and December 2010. They underwent routine clinical work-up including laboratory testing, echocardiography, left and right heart catheterization, holter recordings and endomyocardial biopsy. Primary endpoint (EP) was defined as the combination of cardiovascular death, arrhythmic endpoints (defined as appropriate discharge of implantable cardioverter defibrillator (ICD)) or rehospitalization due to heart failure. The majority of patients presented with slightly impaired left ventricular function (mean LVEF 54.1±9.0%, determined by echocardiography). Endomyocardial biopsies detected cardiac fibrosis in all patients with a variable area percentage of 8% to 32%. Cardiac inflammation was diagnosed as follows: No inflammation in 3.8%, isolated inflammatory cells in 38.5%, a few foci of inflammation in 30.8%, several foci of inflammation in 15.4%, and pronounced inflammation in 7.7% of patients. During follow up (FU) (22.5 months), seven (28%) patients reached the primary EP. Patients with subsequent events showed a higher degree of fibrosis and inflammation in the myocardium by trend. While patients with an inflammation grade 0 or 1 showed an event rate of 18.2%, the subgroup of patients with an inflammation grade 2 presented with an event rate of 25% versus an event rate of 50% in the subgroup of patients with an inflammation grade 3 and 4, respectively (p=0.193). Furthermore, the subgroup of patients with fibrosis grade 1 showed an event rate of 11%, patients with fibrosis grade 2 and 3 presented with an event rate of 33% and 42% respectively (p = 0.160).

Conclusions

Patients with SSc and clinical signs of cardiac involvement presented with mildly impaired LVEF. Prognosis was poor with an event rate of 28% within 22.5 months FU and was associated with the degree of cardiac inflammation and fibrosis.

The Novel Extracellular Cyclophilin A (CyPA) - Inhibitor MM284 Reduces Myocardial Inflammation and Remodeling in a Mouse Model of Troponin I -Induced Myocarditis

Cyclophilins are a group of highly conserved cytosolic enzymes that have a peptidylprolyl cis/trans isomerase activity. Cyclophilin A (CyPA) can be secreted in the extracellular space by inflammatory cells and upon cell death. The presence of CyPA in patients with non-ischemic cardiomyopathy is associated with poor clinical prognosis. Here, we investigated the inhibition of extracellular CyPA in a mouse model of troponin I-induced autoimmune myocarditis using the strictly extracellular CyPA-inhibitor MM284. Since A/J mice develop severe inflammation and fibrosis after immunization with murine cardiac troponin I (mcTn I), we used this model to analyze the effects of an extracellular CyPA inhibition. As extracellular CyPA-inhibitor we used the recently described CsA-derivate MM284. In vitro studies confirmed that MM284 inhibits CyPA-induced monocytic migration and adhesion. A/J mice immunized with mcTnI were treated with MM284 or vehicle every second day. After 28 days, we found a considerable reduction of myocardial injury and fibrosis. Further analysis revealed a reduced myocardial presence of T-cells and macrophages compared to control treated animals. Whereas MMP-9 expression was reduced significantly by MM284, we observed no significant reduction of inflammatory cytokines such as IL-6 or TNFα. Extracellular CyPA plays an important role in autoimmune myocarditis for myocardial damage and fibrosis. Our data suggest a new pharmacological approach for the treatment of myocardial inflammation and reduction of cardiac fibrosis by inhibition of extracellular CyPA.

Rapidly progressive hypertrophic cardiomyopathy in an infant with Noonan syndrome with multiple lentigines: palliative treatment with a rapamycin analog

Noonan syndrome with multiple lentigines (NSML) frequently manifests with hypertrophic cardiomyopathy (HCM). Recently, it was demonstrated that mTOR inhibition reverses HCM in NSML mice. We report for the first time on the effects of treatment with a rapamycin analog in an infant with LS and malignant HCM. In the boy, progressive HCM was diagnosed during the first week of life and a diagnosis of NSML was established at age 20 weeks by showing a heterozygous Q510E mutation in PTPN11. Immunoblotting with antibodies against pERK, pAkt, and pS6RP in fibroblasts demonstrated enhanced Akt/mTOR pathway activity. Because of the patient's critical condition, everolimus therapy was started at age 24 weeks and continued until heart transplantation at age 36 weeks. Prior to surgery, heart failure improved from NYHA stage IV to II and brain natriuretic peptide values decreased from 9,600 to <1,000 pg/ml, but no reversal of cardiac hypertrophy was observed. Examination of the explanted heart revealed severe hypertrophy and myofiber disarray with extensive perivascular fibrosis. These findings provide evidence that Akt/mTOR activity is enhanced in NSML with HCM and suggest that rapamycin treatment could principally be feasible for infantile NSML. The preliminary experiences made in this single patient indicate that therapy should start early to prevent irreversible cardiac remodelling.

Janus kinase 3 regulates renal 25-hydroxyvitamin D 1α-hydroxylase expression, calcitriol formation, and phosphate metabolism

Calcitriol, a powerful regulator of phosphate metabolism and immune response, is generated by 25-hydroxyvitamin D 1α-hydroxylase in the kidney and macrophages. Renal 1α-hydroxylase expression is suppressed by Klotho and FGF23, the expression of which is stimulated by calcitriol. Interferon γ (INFγ) regulates 1α-hydroxylase expression in macrophages through transcription factor interferon regulatory factor-1. INFγ-signaling includes Janus kinase 3 (JAK3) but a role of JAK3 in the regulation of 1α-hydroxylase expression and mineral metabolism has not been shown. Thus, the impact of JAK3 deficiency on calcitriol formation and phosphate metabolism was measured. Renal interferon regulatory factor-1 and 1α-hydroxylase transcript levels, serum calcitriol and FGF23 levels, intestinal phosphate absorption as well as absolute and fractional renal phosphate excretion were significantly higher in jak3 knockout than in wild-type mice. Coexpression of JAK3 increased the phosphate-induced current in renal sodium-phosphate cotransporter-expressing Xenopus oocytes. Thus, JAK3 is a powerful regulator of 1α-hydroxylase expression and phosphate transport. Its deficiency leads to marked derangement of phosphate metabolism.

Down-regulation of inwardly rectifying Kir2.1 K+ channels by human parvovirus B19 capsid protein VP1

Parvovirus B19 (B19V) has previously been shown to cause endothelial dysfunction. B19V capsid protein VP1 harbors a lysophosphatidylcholine producing phospholipase A2 (PLA2). Lysophosphatidylcholine inhibits Na(+)/K(+) ATPase, which in turn may impact on the activity of inwardly rectifying K(+) channels. The present study explored whether VP1 modifies the activity of Kir2.1 K(+) channels. cRNA encoding Kir2.1 was injected into Xenopus oocytes without or with cRNA encoding VP1 isolated from a patient suffering from fatal B19V-induced inflammatory cardiomyopathy or the VP1 mutant (H153A)VP1 lacking a functional PLA2 activity. K(+) channel activity was determined by dual electrode voltage clamp. In addition, Na(+)/K(+)-ATPase activity was estimated from K(+)-induced pump current (I(pump)) and ouabain-inhibited current (I(ouabain)). Injection of cRNA encoding Kir2.1 into Xenopus oocytes was followed by appearance of inwardly rectifying K(+) channel activity (I(K)), which was significantly decreased by additional injection of cRNA encoding VP1, but not by additional injection of cRNA encoding (H153A)VP1. The effect of VP1 on I K was mimicked by lysophosphatidylcholine (1 μg/ml) and by inhibition of Na(+)/K(+)-ATPase with 0.1 mM ouabain. In the presence of lysophosphatidylcholine, I K was not further decreased by additional treatment with ouabain. The B19V capsid protein VP1 thus inhibits Kir2.1 channels, an effect at least partially due to PLA2-dependent formation of lysophosphatidylcholine with subsequent inhibition of Na(+)/K(+)-ATPase activity.

The activating receptor NKG2D of natural killer cells promotes resistance against enterovirus-mediated inflammatory cardiomyopathy

In enterovirus-induced cardiomyopathy, information regarding the detailed impact of natural killer (NK) cells on the outcome of the disease is limited. We therefore hypothesized that NK cells and certain NK cell receptors determine the different outcome of coxsackievirus B3 (CVB3) myocarditis. Here, we demonstrate in murine models that resistance to chronic CVB3 myocarditis in immunocompetent C57BL/6 mice is characterized by significantly more mature CD11b(high) NK cells, the presence of NKG2D on NK cells, and enhanced NKG2D-dependent cytotoxicity compared to CVB3-susceptible A.BY/SnJ mice. The highly protective role of NKG2D in myocarditis was further proven by in vivo neutralization of NKG2D as well as in NKG2D-deficient mice but was shown to be independent of CD8(+) T-cell-dependent immunity. Moreover, the adoptive transfer of immunocompetent C57BL/6 NK cells pre- (day -1) as well as post-infectionem (day +2) displayed the potential to prevent permissive A.BY/SnJ mice from a progressive outcome of CVB3 myocarditis reflected by significantly improved cardiopathology and heart function. Altogether, our results provide firm evidence for a protective role of NKG2D-activated NK cells in CVB3 myocarditis leading to an effective virus clearance, thus offering novel therapeutic options in the treatment of virus-induced myocarditis.

Down-regulation of K⁺ channels by human parvovirus B19 capsid protein VP1

Parvovirus B19 (B19V) can cause inflammatory cardiomyopathy and endothelial dysfunction. Pathophysiological mechanisms involved include lysophosphatidylcholine producing phospholipase A2 (PLA2) activity of the B19V capsid protein VP1. Most recently, VP1 and lysophosphatidylcholine have been shown to inhibit Na(+)/K(+) ATPase. The present study explored whether VP1 modifies the activity of Kv1.3 and Kv1.5 K(+) channels. cRNA encoding Kv1.3 or Kv1.5 was injected into Xenopus oocytes without or with cRNA encoding VP1 isolated from a patient suffering from fatal B19V-induced myocarditis. K(+) channel activity was determined by dual electrode voltage clamp. Injection of cRNA encoding Kv1.3 or Kv1.5 into Xenopus oocytes was followed by appearance of Kv K(+) channel activity, which was significantly decreased by additional injection of cRNA encoding VP1, but not by additional injection of cRNA encoding PLA2-negative VP1 mutant (H153A). The effect of VP1 on Kv current was not significantly modified by transcription inhibitor actinomycin (10 μM for 36 h) but was mimicked by lysophosphatidylcholine (1 μg/ml). The B19V capsid protein VP1 inhibits host cell Kv channels, an effect at least partially due to phospholipase A2 (PLA) dependent formation of lysophosphatidylcholine.

Role of cardiovascular magnetic resonance imaging (CMR) in the diagnosis of acute and chronic myocarditis

The aetiopathogenesis of acute and chronic myocarditis is rather complex as a great variety of infectious agents can induce cardiac inflammation. Moreover, many systemic and autoimmune diseases such as sarcoidosis, giant cell myocarditis and systemic lupus erythematodes, drugs and toxins have been described as non-infectious causes of inflammatory heart disorders. Myocarditis may cause sudden death and lead to dilated cardiomyopathy. The correct and timely diagnosis of myocarditis is still a difficult clinical challenge, since the clinical spectrum of myocarditis is broad and comprises (amongst others) even those patients with no symptoms or those presenting with acute cardiogenic shock. Although endomyocardial biopsy still represents the gold standard for the diagnosis of myocarditis, new non-invasive imaging techniques such as cardiovascular magnetic resonance (CMR) imaging promise the non-invasive diagnosis of myocarditis. Considering the hallmarks of acute and chronic myocarditis (accumulation of inflammatory cells; swelling, necrosis and/or apoptosis of cardiomyocytes; increase in extracellular space and water content; myocardial remodelling with fibrotic tissue replacement), an imaging modality such as CMR that enables non-invasive detection of changes in myocardial tissue composition is highly valuable and welcome. This review will focus on the 'clinical role' of CMR in the diagnosis of acute and chronic myocarditis.

Stiffness of left ventricular cardiac fibroblasts is associated with ventricular dilation in patients with recent-onset nonischemic and nonvalvular cardiomyopathy

BACKGROUND

Ventricular dilation is known as a pivotal predictor in recent-onset cardiomyopathy (ROCM), but its pathophysiology is not fully understood. In the present study we investigated whether single-cell stiffness of right and left ventricular-derived fibroblasts has an effect on cardiac phenotype in patients with ROCM.

METHODS AND RESULTS

Patients with endomyocardial biopsy-proven ROCM were included (n=10). Primary cardiac fibroblasts (CFBs) were cultured from left and right ventricular endomyocardial biopsies and their single-cell stiffness was analyzed by quantification of Young's modulus using colloidal probe atomic force microscopy. Cardiac fibrosis was analyzed by Masson's trichrome staining. CFBs from the left ventricle showed significantly decreased stiffness when compared with CFBs from the right ventricle, indexed by decreased stiffness (Young's modulus 3,374±389 vs. 4,837±690 Pa; P<0.05). Young's modulus of CFBs derived from the left ventricle correlated negatively with the left ventricular end-diastolic dimension derived from 2-dimensional echocardiography (R(2)=0.77; P<0.01). Neither left nor right ventricular fibrosis correlated with the respective ventricular dimensions.

CONCLUSIONS

Our data suggest that a decrease in single-cell stiffness of left ventricular fibroblasts could trigger left ventricular dilation in patients with ROCM. This implies a new potential mechanism for the ventricular dilation with this disease.

Gremlin-1 identifies fibrosis and predicts adverse outcome in patients with heart failure undergoing endomyocardial biopsy

BACKGROUND

Gremlin-1 (Grem1), an antagonist of bone morphogenetic proteins, is involved in fibrotic tissue formation in kidney and lung. The impact of myocardial Grem1 expression is unknown. We investigated the prognostic value of Grem1 expression in 214 consecutive patients with nonischemic heart failure (HF) undergoing endomyocardial biopsy.

METHODS

In all patients, the following risk factors were assessed: Grem1 expression (semiquantitative score scheme ranging from 1 to 4), presence of inflammatory markers, detection of viral genome, left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD), New York Heart Association functional class (NYHA), troponin I, and B-type natriuretic peptide. Degree of myocardial fibrosis was defined as an index. Study end point was a combination of all-cause death and HF-related rehospitalization within 3 years of follow-up.

RESULTS

Grem1 expression significantly correlated with the degree of myocardial fibrosis (correlation coefficient r = 0.619; P < .0001). Patients with the highest Grem1 expression (score 4) showed the most severely impaired LVEF and highest LVEDD (P < .0001 and P = .030, respectively, for comparison of semiquantitative scores). During follow-up, 33 patients (15.4%) reached the study end point. Grem1 expression and NYHA ≥II were independent predictors of the end point (Grem1: hazard ratio [HR] 7.5, 95% confidence interval [CI] 1.8-32.2; P = .006; NYHA ≥II: HR 2.0, 95% CI 1.0-4.1; P = .048).

CONCLUSIONS

Grem1 correlates with the degree of myocardial fibrosis and left ventricular dysfunction and is an independent predictor of adverse outcome in patients with nonischemic HF.

Molecular phenotypes of human parvovirus B19 in patients with myocarditis

AIM: To investigate molecular phenotypes of myocardial B19V-infection to determine the role of B19V in myocarditis and dilated cardiomyopathy (DCM).

METHODS: Endomyocardial biopsies (EMBs) from 498 B19V-positive patients with myocarditis and DCM were analyzed using molecular methods and functional experiments. EMBs were obtained from the University Hospitals of Greifswald and Tuebingen and additionally from 36 German cardiology centers. Control tissues were obtained at autopsy from 34 victims of accidents, crime or suicide. Identification of mononuclear cell infiltrates in EMBs was performed using immunohistological staining. Anti-B19V-IgM and anti-B19V-IgG were analyzed by enzyme-linked immunosorbent assay (ELISA). B19V viral loads were determined using in-house quantitative real-time polymerase chain reaction (PCR). For B19V-genotyping a new B19V-genotype-specific restriction fragment length polymorphism (RFLP)-PCR was established. B19V-genotyping was verified by direct DNA-sequencing and sequences were aligned using BLAST and BioEdit software. B19V P6-promoter and HHV6-U94-transactivator constructs were generated for cell culture experiments. Transfection experiments were conducted using human endothelial cells 1. Luciferase reporter assays were performed to determine B19V-replication activity. Statistical analysis and graphical representation were calculated using SPSS and Prism5 software.

RESULTS: The prevalence of B19V was significantly more likely to be associated with inflammatory cardiomyopathy (iCMP) compared to uninflamed DCM (59.6% vs 35.3%) (P < 0.0001). The detection of B19V-mRNA replication intermediates proved that replication of B19V was present. RFLP-PCR assays showed that B19V-genotype 1 (57.4%) and B19V-genotype 2 (36.7%) were the most prevalent viral genotypes. B19V-genotype 2 was observed more frequently in EMBs with iCMP (65.0%) compared to DCM (35%) (P = 0.049). Although there was no significant difference in gender-specific B19V-loads, women were more frequently infected with B19V-genotype 2 (44.6%) than men (36.0%) (P = 0.0448). Coinfection with B19V and other cardiotropic viruses was found in 19.2% of tissue samples and was associated with higher B19V viral load compared to B19V-monoinfected tissue (P = 0.0012). The most frequent coinfecting virus was human herpes virus 6 (HHV6, 16.5%). B19V-coinfection with HHV6 showed higher B19V-loads compared to B19V-monoinfected EMBs (P = 0.0033), suggesting that HHV6 had transactivated B19V. In vitro experiments confirmed a 2.4-fold increased B19V P6-promoter activity by the HHV6 U94-transactivator.

CONCLUSION: The finding of significantly increased B19V loads in patients with histologically proven cardiac inflammation suggests a crucial role of B19V-genotypes and reactivation of B19V-infection by HHV6-coinfection in B19V-associated iCMP. Our findings suggest that B19V-infection of the human heart can be a causative event for the development of an endothelial cell-mediated inflammatory disease and that this is related to both viral load and genotype.

Cardiovascular magnetic resonance risk stratification in patients with clinically suspected myocarditis

BACKGROUND

The diagnosis of myocarditis is challenging due to its varying clinical presentation. Since myocarditis can be associated with significant 5-year mortality, and postmortem data show myocarditis in almost 10% of all adults suffering sudden cardiac death, individual risk stratification for patients with suspected myocarditis is of great clinical interest. We sought to demonstrate that patients with clinically suspected myocarditis and a normal cardiovascular magnetic resonance (CMR) according to our definition have a good prognosis, independent of their clinical symptoms and other findings.

METHODS

Prospective clinical long-term follow-up of consecutive patients undergoing CMR for work-up of clinically suspected myocarditis at our institution in 2007-2008.

RESULTS

Follow-up was available for n=405 patients (all-comers, 54.8% inpatients, 38% outpatient referrals from cardiologists). Median follow-up time was 1591 days. CMR diagnosis was "myocarditis" in 28.8%, "normal" in 55.6% and "other pathology" in 15.6%. Normal CMR was defined as normal left ventricular (LV) volumes and normal left ventricular ejection fraction (LV-EF) in the absence of late Gadolinium Enhancement (LGE). The overall mortality was 3.2%. There were seven cardiac deaths during follow-up, in addition one aborted SCD and two patients had appropriate internal cardioverter defibrillator (ICD) shocks - all of these occurred in patients with abnormal CMR. Kaplan-Meier analysis with log-rank test showed significant difference for major adverse cardiac events (cardiac death, sudden cardiac death (SCD), ICD discharge, aborted SCD) between patients with normal and abnormal CMR (p=0.0003).

CONCLUSION

In our unselected population of consecutive patients referred for CMR work-up of clinically suspected myocarditis, patients with normal CMR have a good prognosis independent of their clinical symptoms and other findings.

Heme oxygenase-1 mediates oxidative stress and apoptosis in coxsackievirus B3-induced myocarditis

BACKGROUND

Heme oxygenase-1 (HO-1), which is suggested to play a role in defending the organism against oxidative stress-mediated injuries, can be induced by diverse factors including viruses and iron. As coxsackievirus B3 (CVB3)-infected SWR/J mice susceptible for chronic myocarditis were found to have a significant iron incorporation and HO-1 upregulation in the myocardium, we aimed to investigate the molecular interplay between HO-1 expression and iron homeostasis in the outcome of viral myocarditis.

METHODS AND RESULTS

In susceptible SWR/J mice, but not in resistant C57BL/6 mice, we observed at later stages of CVB3 myocarditis significant iron deposits in macrophages and also in cardiomyocytes, which were spatially associated with oxidative stress, upregulation of HO-1 and caspase-3 activation. HO-1, which is also expressed in cultivated RAW 264.7 macrophages upon incubation with iron and/or CVB3, could be downregulated by inhibition of NO/iNOS using L-NAME. Moreover, specific inhibition of HO-1 by tin mesoporphyrin revealed a suppression of superoxide production in iron and/or CVB3-treated macrophages. The molecular relationship of HO-1 and caspase-3 activation was proven by downregulation with HO-1 siRNA in iron- and/or CVB3-treated cultivated cells. Importantly, iron was found to increase viral replication in vitro.

CONCLUSION

These results indicate that HO-1 induces a paracrine signalling in macrophages via reactive oxygen species production, mediating apoptosis of heart muscle cells at later stages of myocarditis. Notably, in genetically susceptible mice iron potentiates the detrimental effects of CVB3 by the NO/HO-1 pathway, thus increasing cardiac pathogenicity.

Enhanced stem cell migration mediated by VCAM-1/VLA-4 interaction improves cardiac function in virus-induced dilated cardiomyopathy

Endogenous circulation of bone marrow-derived cells (BMCs) was observed in patients with dilated cardiomyopathy (DCM) who showed cardiac upregulation of Vascular Cell Adhesion Protein-1 (VCAM-1). However, the underlying pathophysiology is currently unknown. Thus, we aimed to analyze circulation, migration and G-CSF-based mobilization of BMCs in a murine model of virus-induced DCM. Mice with coxsackievirus B3 (CVB3) induced DCM and healthy controls were analyzed regarding their myocardial homing factors by PCR. To determine cardiac VCAM-1 expression ELISA and immunohistochemistry were applied. Flow cytometry was performed to analyze BMCs. Cardiac diameters and function were evaluated by echocardiography before and 4 weeks after G-CSF treatment. In murine CVB3-induced DCM an increase of BMCs in peripheral blood and a decrease of BMCs in bone marrow was observed. We found an enhanced migration of Very Late Antigen-4 (VLA-4⁺) BMCs to the diseased heart overexpressing VCAM-1 and higher numbers of CD45⁻CD34⁻Sca-1⁺ and CD45⁻CD34⁻c-kit⁺ cells. Mobilization of BMCs by G-CSF boosted migration along the VCAM-1/VLA-4 axis and reduced apoptosis of cardiomyocytes. Significant improvement of cardiac function was detected by echocardiography in G-CSF-treated mice. Blocking VCAM-1 by a neutralizing antibody reduced the G-CSF-dependent effects on stem cell migration and cardiac function. This is the first study showing that in virus-induced DCM VCAM-1/VLA-4 interaction is crucial for recruitment of circulating BMCs leading to beneficial anti-apoptotic effects resulting in improved cardiac function after G-CSF-induced mobilization.

Regulation of mineral metabolism by lithium

Lithium, an inhibitor of glycogen synthase kinase 3 (GSK3), is widely used for the treatment of mood disorders. Side effects of lithium include nephrogenic diabetes insipidus, leading to renal water loss. Dehydration has in turn been shown to downregulate Klotho, which is required as co-receptor for the downregulation of 1,25(OH)2D3 formation by fibroblast growth factor 23 (FGF23). FGF23 decreases and 1,25(OH)2D3 stimulates renal tubular phosphate reabsorption. The present study explored whether lithium influences renal Klotho expression, FGF23 serum levels, 1,25(OH)2D3 formation, and renal phosphate excretion. To this end, mice were analyzed after a 14-day period of sham treatment or of treatment with lithium (200 mg/kg/day subcutaneously). Serum antidiuretic hormone (ADH), FGF23, and 1,25(OH)2D3 concentrations were determined by ELISA or EIA, renal Klotho protein abundance and GSK3 phosphorylation were analyzed by Western blotting, and serum phosphate and calcium concentration by photometry. Lithium treatment significantly increased renal GSK3 phosphorylation, enhanced serum ADH and FGF23 concentrations, downregulated renal Klotho expression, stimulated renal calcium and phosphate excretion, and decreased serum 1,25(OH)2D3 and phosphate concentrations. In conclusion, lithium treatment upregulates FGF23 formation, an effect paralleled by substantial decrease of serum 1,25(OH)2D3, and phosphate concentrations and thus possibly affecting tissue calcification.