Rudolf Meyer

Identification and Expression of δ-Isoforms of the Multifunctional Ca2+/Calmodulin-Dependent Protein Kinase in Failing and Nonfailing Human Myocardium

Despite its importance for the regulation of heart function, little is known about the isoform expression of the multifunctional Ca2+/calmodulin-dependent protein kinase (CaMKII) in human myocardium. In this study, we investigated the spectrum of CaMKII isoforms delta2, delta3, delta4, delta8, and delta9 in human striated muscle tissue. Isoform delta3 is characteristically expressed in cardiac muscle. In skeletal muscle, specific expression of a new isoform termed delta11 is demonstrated. Complete sequencing of human delta2 cDNA, representing all common features of the investigated CaMKII subclass, revealed its high homology to the corresponding rat cDNA. Comparative semiquantitative reverse transcription-polymerase chain reaction analyses from left ventricular tissues of normal hearts and from patients suffering from dilated cardiomyopathy showed a significant increase in transcript levels of isoform delta3 relative to the expression of glyceraldehyde-3-phosphate dehydrogenase in diseased hearts (101. 6+/-11.0% versus 64.9+/-9.9% in the nonfailing group; P<0.05, n=6). Transcript levels of the other investigated cardiac CaMKII isoforms remained unchanged. At the protein level, by using a subclass-specific antibody, we observed a similar increase of a delta-CaMKII-specific signal (7.2+/-1.0 versus 3.8+/-0.7 optical density units in the nonfailing group; P<0.05, n=4 through 6). The diseased state of the failing hearts was confirmed by a significant increase in transcript levels for atrial natriuretic peptide (292. 9+/-76.4% versus 40.1+/-3.2% in the nonfailing group; P<0.05, n=3 through 6). Our data characterize for the first time the delta-CaMKII isoform expression pattern in human hearts and demonstrate changes in this expression pattern in heart failure.

Non-HLA antibodies targeting vascular receptors enhance alloimmune response and microvasculopathy after heart transplantation.

Background Non–human leukocyte antigen antibodies (Abs) targeting vascular receptors are implicated in the pathogenesis of renal allograft vascular rejection and in progressive vasculopathy in patients with systemic sclerosis. Methods We prospectively tested in 30 heart transplant recipients the impact of Abs directed against endothelin-1 type A (ETAR) and angiotensin II type 1 receptors (AT1R, cell-enzyme–linked immunosorbent assay) at time of transplantation and during the first posttransplantation year on cellular and Ab-mediated rejection (immunohistochemistry, C3d, and immunoglobulins) and microvasculopathy in endomyocardial biopsy. Results Cellular rejection, Ab-mediated rejection, and microvasculopathy was found in 40% and 13%, 57% and 18%, and 37% and 40% of biopsies at 1 month and 1 year posttransplantation, respectively. Maximum levels of AT1R and ETAR Abs were higher in patients with cellular (16.5±2.6 vs. 9.4±1.3; P=0.021 and 16.5±2.5 vs. 9.9±1.9; P=0.041) and Ab-mediated rejection (19.0±2.6 vs. 10.0±1.3; P=0.004 and 19.4±2.7 vs. 9.0±1.7; P=0.002), as compared with patients who had no rejection. Patients with elevated AT1R Abs (53% [16/30]) or ETAR Abs (50% [15/30]; pretransplantation prognostic rejection cutoff >16.5 U/L) presented more often with microvasculopathy (both, 67% vs. 23%; P=0.048) than patients without. Conclusions Elevated levels of AT1R and ETAR Abs are associated with cellular and Ab-mediated rejection and early onset of microvasculopathy and should be routinely monitored after heart transplantation.

Comparison of porcine xenografts and homografts for pulmonary valve replacement in children

BACKGROUND Due to the limited availability of homografts, different alternatives are used for replacement of the pulmonary valve. This study investigates the value of porcine stentless pulmonary xenografts in pediatric cardiac patients. METHODS Twenty-three pediatric xenograft (size 10 to 21 mm) recipients were compared with 23 homograft (size 9 to 21 mm) recipients. RESULTS Hospital mortality was 2 of 23 patients in the xenograft group and 3 of 23 in the homograft group (NS). Six out of 20 xenografts and 1 of 19 homografts were stenotic after 1 year (p = 0.011). Xenograft stenoses were mainly located at the distal anastomosis, while the leaflets were preserved. Homografts showed valvular stenoses and wall calcification. The 1 year freedom from reoperation was 77% in the xenograft and 93% in homograft recipients (NS), and from transcatheter intervention 84% and 100% (p = 0.004), respectively. Transcatheter intervention in 7 xenograft patients and 1 homograft recipient improved stenosis gradients from 65 to 40 mm Hg (mean) in 6 out of 8 patients. Explanted xenografts showed a loss of elastic membranes and proliferating connective tissue scars coated with activated endothelium. CONCLUSIONS Xenografts demonstrated a higher incidence of supravalvular obstructions, which were possibly due to unfavorable hemodynamics at the distal anastomosis. Histological findings additionally indicated a pronounced immunological response. Interventional angioplasty lowered the rate of reoperation. Thus, the use of xenografts in children can be accepted as a second choice when a homograft is unavailable.

TWIST1 regulates the activity of ubiquitin proteasome system via the miR-199/214 cluster in human end-stage dilated cardiomyopathy.

BACKGROUND The transcription factor TWIST1 has been described to regulate the microRNA (miR)-199/214 cluster. Genetic disruption of TWIST1 resulted in a cachectic phenotype and early death of the knock-out mice. This might be connected to the activity of the ubiquitin-proteasome-system (UPS), as miR-199a has been suggested to regulate the ubiquitin E2 ligases Ube2i and Ube2g1. METHODS Cardiac tissue from explanted hearts of 42 patients with dilated cardiomyopathy and 20 healthy donor hearts were analysed for protein expression of TWIST1 and its inhibitors Id-1, MuRF-1 and MAFbx, the expression of miR-199a, -199b and -214, as well as the activity of the UPS by using specific fluorogenic substrates. RESULTS TWIST1 was repressed in patients with dilated cardiomyopathy by 43% (p=0.003), while Id1 expression was unchanged. This was paralleled by a reduced expression of miR-199a by 38 ± 9% (p=0.053), miR-199b by 36 ± 13% (p=0.019) and miR-214 by 41 ± 11% (p=0.0158) compared to donor hearts. An increased peptidylglutamyl-peptide-hydrolysing activity (p<0.0001) was observed in the UPS, while the chymotrypsin-like and trypsin-like activities were unchanged. The protein levels of the rate limiting ubiquitin E3-ligases MuRF-1 and MAFbx were up-regulated (p=0.005 and p=0.0156, respectively). Mechanistically silencing of TWIST1 using siRNA in primary rat cardiomyocytes led to a down-regulation of the miR-199/214 cluster and to a subsequent up-regulation of Ube2i. CONCLUSION The TWIST1/miR-199/214 axis is down-regulated in dilated cardiomyopathy, which is likely to play a role in the increased activity of the UPS. This may contribute to the loss of cardiac mass during dilatation of the heart.

Papillary Fibroelastoma of the Tricuspid Valve Seen on Magnetic Resonance Imaging

A 72-year–old female patient with atypical chest pain and atherosclerotic risk profile was referred for cardiac magnetic resonance imaging at 3.0 Tesla (Phillips Achieva, Phillips Medical Systems, Best, The Netherlands), sus pected of having coronary artery disease. A resting ECG showed no signs of ischemia or chronic myocardial infarction (Figure 1A). Routinely performed echocardiography revealed a small suspicious mass at the tricuspid valve (Figure 1B). Cardiac magnetic resonance cine imaging revealed normal left ventricular function but, at rest, hypokinesia of the lateral wall of the basal slice. As an additional finding, an 8×8-mm, highly mobile, spherical pedunculate mass attached to the posterior tricuspid valve leaflet was found (Figure 2). T1-weighted images revealed the mass to be homogeneous but with higher signal intensity compared …

Cellular allograft rejection affecting the donor aorta after combined heart-lung transplantation.

BACKGROUND Infectious pseudoaneurysms of the ascending aorta are a recognized major complication after heart-lung transplantation. METHOD This report describes an unusual and previously unreported complication, that of cellular allograft rejection, which caused a pseudoaneurysm of the donors ascending aorta in a patient who underwent combined heart-lung transplantation. Repair was performed by primary suture after mobilization of the aortic segments. RESULT On histological examination the resected aneurysm showed evidence of proliferative vasculitis with perivascular infiltration of the vasa vasorum by mononuclear cells. The mononuclear cells were identified as CD4+ and CD8+ by immunohistological staining. CONCLUSIONS This report shows that cellular allograft rejection may affect the donor aorta after heart-lung transplantation and may result in pseudoaneurysm formation, even under triple-drug immunosuppression after ABO-compatible allograft transplantation.

EPICARDIAL AND MICROVASCULAR GRAFT VESSEL DISEASE IN CHILDREN: INCIDENCE, COURSE AND PROGNOSIS

AIM Graft vessel disease (GVD) is one of the main limiting factors to long-term survival after adult heart transplantation (HTx). The incidence of epicardial and microvascular GVD in paediatric patients was studied. METHODS A total of 137 coronary angiographies from 130 paediatric HTx and heart and lung transplant (HLTx) patients (70 male, 60 female, aged 0-18 y) were evaluated according to the Stanford classification and its supplements (minor vessel alterations). In H&E stainings from right ventricular endomyocardial biopsies (EMB = 397), light microscopic diagnosis of acute cellular rejection (ISHLT classification) and vascular reaction (morphology of endothelial cells and vessel walls) was performed. RESULTS Moderate rejection was present in 32.8% and severe rejection in 13.3% of EMB. Microvascular EC swelling was found in 33.5% and vessel wall thickening in 53.8% of EMB. The results of the coronary angiographic investigations were: Stanford lesions = 61.2%, peripheral obliterations = 52.5%, diameter fluctuations = 86.3%, pathologic tapering = 64.0%, calcifications = 10.8%. Long-term survivors (> or =5 y) showed macrovascular alterations in 78% of cases and microvascular alterations in 67% of cases. CONCLUSION The development of micro- and macrovascular GVD is one of the predominant complications in long-term survivors after paediatric HTx and HLTx.