B. Bohms

Plasma biomarkers of myocardial fibrosis and remodeling in terminal heart failure patients supported by mechanical circulatory support devices.

BACKGROUND In this study we analyzed putative biomarkers for myocardial remodeling in plasma from 55 endstage heart failure patients with the need for mechanical circulatory support (MCS). We compared our data to 40 healthy controls and examined if MCS by either ventricular assist devices or total artificial hearts has an impact on plasma concentrations of remodeling biomarkers. METHODS & RESULTS Plasma biomarkers were analysed pre and 30 days post implantation of a MCS device using commercially available enzyme linked immunosorbent assays (ELISA). We observed that the plasma concentrations of remodeling biomarkers: tissue inhibitor of metalloproteinase 1 (TIMP1), tenascin C (TNC), galectin 3 (LGALS3), osteopontin (OPN) and of neurohumoral biomarker brain natriuretic peptide (BNP), are significantly elevated in patients with terminal heart failure compared to healthy controls. We did not find elevated plasma concentrations for matrix metalloproteinase 2 (MMP2) and procollagen I C-terminal peptide (PCIP). However, only BNP plasma levels were reduced by MCS, whereas the concentrations of remodeling biomarkers remained elevated or even increased further 30 days after MCS. LGALS3 plasma concentrations at device implantation were significantly higher in patients who did not survive MCS due to multi organ failure (MOF). CONCLUSIONS Our findings indicate that mechanical unloading in endstage heart failure is not reflected by a rapid reduction of remodeling plasma biomarkers.

De novo desmin mutation N116S is associated with arrhythmogenic right ventricular cardiomyopathy

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease, frequently accompanied by sudden cardiac death and terminal heart failure. Genotyping of ARVC patients might be used for palliative treatment of the affected family. We genotyped a cohort of 22 ARVC patients referred to molecular genetic screening in our heart center for mutations in the desmosomal candidate genes JUP, DSG2, DSC2, DSP and PKP2 known to be associated with ARVC. In 43% of the cohort, we found disease-associated sequence variants. In addition, we screened for desmin mutations and found a novel desmin-mutation p.N116S in a patient with ARVC and terminal heart failure, which is located in segment 1A of the desmin rod domain. The mutation leads to the aggresome formation in cardiac and skeletal muscle without signs of an overt clinical myopathy. Cardiac aggresomes appear to be prominent, especially in the right ventricle of the heart. Viscosimetry and atomic force microscopy of the desmin wild-type and N116S mutant isolated from recombinant Escherichia coli revealed severe impairment of the filament formation, which was supported by transfections in SW13 cells. Thus, the gene coding for desmin appears to be a novel ARVC gene, which should be included in molecular genetic screening of ARVC patients.

No Association Between Single Nucleotide Polymorphisms and the Development of Nephrotoxicity After Orthotopic Heart Transplantation

BACKGROUND Survival for heart transplantation (HTx) patients is limited by nephrotoxicity of the calcineurin inhibitors cyclosporine and tacrolimus. To determine whether genetic factors are involved in the development of renal dysfunction under immunosuppressive therapy, we screened various genes for sequence variations. METHODS In a case-control study we analyzed in parallel polymorphisms within the transforming growth factor-beta1 gene (TGF-beta1; L10P, R25P), the multidrug resistance gene MDR 1 (A893T/S) and the CYP3A5 gene (CYP3A5*1/*3 allele). In total, we included 53 cardiac allograft recipients with renal insufficiency (serum creatinine >or=1.8 mg/dl and glomerular filtration rate <50 ml/min/1.73 m(2)) and 53 patients with normal renal function as controls. The controls were matched with patients for age, gender and post-HTx time. The polymorphisms were assessed by denaturing high-performance liquid chromatography (dHPLC) and direct sequencing. We performed univariate and multivariate logistic regression analysis to assess the association between different gene variants and renal dysfunction. RESULTS No significant (p > 0.05) relationship was found between the polymorphisms investigated and the susceptibility of renal insufficiency under immunosuppressive therapy. CONCLUSIONS Our data do not justify genotyping of the investigated single nucleotide polymorphisms (SNPs) to assess the development of renal dysfunction post-HTx.

The biomarker plasma galectin-3 in advanced heart failure and survival with mechanical circulatory support devices.

BACKGROUND During screening of heart transplantation (HTx) candidates supported by ventricular assist devices (VADs) for plasma biomarkers we found that galectin-3 (Gal-3) was increased pre-operatively in patients who later died during VAD support. Therefore, we analyzed the predictive value of plasma Gal-3 in the context of other potential clinical risk factors for death on device (DOD) in a cohort of 175 VAD patients. METHODS We analyzed numerous clinical factors and plasma Gal-3 levels of 175 VAD patients before device implantation. Eighty VAD patients were successfully bridged to HTx (BTT, 45.7%), 80 (45.7%) died on VAD, 2 recovered on device (BTR, 1.1%) and 13 (7.4%) were still on device. Uni- and multivariate analyses were performed to assess the importance of Gal-3 with respect to other clinical factors. Myocardial gene expression of Gal-3 was investigated in apex samples by RT-PCR (n = 30) and Western blotting (n = 45). RESULTS Plasma Gal-3 levels were higher in VAD patients than in controls (16.6 ± 9.3 vs 9.5 ± 3.9 ng/ml, p < 0.0001). Cox regression showed several clinical factors and type of VAD as independent outcome predictors, but Gal-3 was not among them. Using the regression equation we grouped patients according to their factor constellation for prediction of survival on VAD. We propose a calculation method for VAD survival prediction. Gal-3 mRNA and protein were detectable in failing myocardium, but did not correlate with its plasma concentration. CONCLUSIONS Galectin-3 levels are associated with severe heart failure but do not provide sufficient discrimination for prediction of outcomes after VAD implantation. Importantly, we were unable to confirm myocardial tissue as a primary source for the observed plasma elevations of Gal-3.

Regulation of cyclic adenosine monophosphate release by selective β2-adrenergic receptor stimulation in human terminal failing myocardium before and after ventricular assist device support

BACKGROUND Response to catecholamines is blunted in terminal heart failure due to β-receptor downregulation and uncoupling from adenylyl cyclase (AC). Improved myocardial responsiveness to catecholamines after ventricular assist device (VAD) support is associated with upregulation of β1-adrenergic receptors (β1-ARs). Little is known about the regulation of AC and β2-AR coupling after VAD; moreover β2-AR stimulation during VAD was claimed to induce myocardial recovery. METHODS We analyzed in VAD-supported human myocardium the regulation of AC activity upon β1-AR and selective β2-AR stimulation in 8 non-failing hearts (NF) and 17 paired samples of VAD patients. AC messenger RNA was measured by TaqMan. AC was stimulated via β2-AR using clenbuterol (β2-AR agonist) and bisoprolol (β1-AR blocker). Organ bath experiments were done with trabeculae from both ventricles. Samples were stratified according to chronic or acute heart failure history. RESULTS Isoprenaline-induced AC activity was downregulated (p < 0.001) pre-VAD and increased significantly (p < 0.05) after unloading (mean ± standard deviation pmole/mg/min) in NF (47.9 ± 14.9), pre-VAD (24.35 ± 13.3), and post-VAD (50.04 ± 50.25). Forskolin stimulation revealed significant (p < 0.05) upregulation of AC activity during VAD, especially in acutely failing hearts (NF, 192.1 ± 68.7; pre-VAD, 191.1 ± 60.4; post-VAD, 281.5 ± 133). However, forskolin stimulation relative to isoprenaline-induced inotropy remained reduced before and after VAD compared with NF. The selective stimulation of β2-AR did not reveal influence of VAD support on β2-AR-AC coupling. Stimulation of ventricular trabeculae by > 100 μmole/liter clenbuterol revealed negative inotropic responses. CONCLUSIONS VAD does not influence β2-AR coupling to AC stimulation. Elevated response to catecholamines after VAD support is influenced by β1-AR upregulation and modulation of AC activity. Restoration of β-adrenergic responsiveness was restricted to acutely failing hearts.