E.J. Birks

Clinical Recovery From End-Stage Heart Failure Using Left-Ventricular Assist Device and Pharmacological Therapy Correlates With Increased Sarcoplasmic Reticulum Calcium Content but Not With Regression of Cellular Hypertrophy

Background—Left ventricular assist device (LVAD) treatment is known to lead to structural and functional cellular modifications in the heart. The relevance of these changes for clinical recovery is unknown. Methods and Results—We compared properties of cardiomyocytes obtained from tissue taken at explantation of the LVAD in patients with clinical recovery with those obtained from hearts of patients who did not show clinical recovery, thus requiring transplantation. Compared with myocytes taken at implantation, both the recovery and nonrecovery groups showed ≈50% reduction in cell capacitance, an index of cell size. However, action potential duration shortened, L-type Ca2+ current fast inactivation was more rapid, and sarcoplasmic reticulum Ca2+ content was increased in the recovery compared with the nonrecovery group. Conclusions—These results show that specific changes in excitation-contraction coupling, and not regression of cellular hypertrophy, are specifically associated with clinical recovery after LVAD and further identify sarcoplasmic reticulum Ca2+ handling as a key functional determinant in patients with heart failure.

Upregulation of the Bcl-2 family of proteins in end stage heart failure

OBJECTIVES To elucidate the pattern of expression of four members of the Bcl-2 family of proteins and to correlate this with terminal deoxynucleotidyl transferase [TdT]-mediated dUTP nick end labelling (TUNEL) and DNA fragmentation. BACKGROUND Apoptosis has been implicated as a possible mechanism in the development of heart failure. However, the mechanisms involved remain unclear. METHODS We have studied the expression of four members of the Bcl-2 family that are involved in the regulation of apoptosis and analyzed DNA fragmentation as a marker of apoptosis and as a biochemical criterion to distinguish between apoptosis and necrosis in dilated cardiomyopathy (DCM), ischemic heart disease (IHD) and normal donors. RESULTS Western blot analysis and immunocytochemistry of the proapoptotic and antiapoptotic Bcl-2 proteins demonstrated significantly higher levels of all these proteins in the diseased groups compared with normal donors. Additionally, Bax was significantly higher in the IHD group compared with DCM. Terminal deoxynucleotidyl transferase [TdT]-mediated dUTP nick end labelling analysis demonstrated a significantly higher percentage of TUNEL-positive cells in the diseased groups compared with the control. Genomic DNA extraction of ventricular myocardial tissue showed no demonstrable DNA laddering for any of the groups. CONCLUSIONS The significant increases in the levels of the proapoptotic proteins Bak and Bax and the higher percentage of TUNEL-positive cells in both diseased groups suggests the presence of ongoing apoptosis. However, increases in the antiapoptotic proteins, Bcl-2 and Bcl-xL, suggest a possible concomitant, compensatory antiapoptotic mechanism in patients with heart failure.

Elevated p53 expression is associated with dysregulation of the ubiquitin-proteasome system in dilated cardiomyopathy

AIMS The molecular mechanisms that regulate cardiomyocyte apoptosis and their role in human heart failure (HF) are uncertain. Expression of the apoptosis regulator p53 is governed by minute double minute 2 (MDM2), an E3 enzyme that targets p53 for ubiquitination and proteasomal processing, and by the deubiquitinating enzyme, herpesvirus-associated ubiquitin-specific protease (HAUSP), which rescues p53 by removing ubiquitin chains from it. Here, we examined whether elevated expression of p53 was associated with dysregulation of ubiquitin-proteasome system (UPS) components and activation of downstream effectors of apoptosis in human dilated cardiomyopathy (DCM). METHODS AND RESULTS Left ventricular myocardial samples were obtained from patients with DCM (n = 12) or from non-failing (donor) hearts (n = 17). Western blotting and immunohistochemistry revealed that DCM tissues contained elevated levels of p53 and its regulators MDM2 and HAUSP (all P < 0.01) compared with non-failing hearts. DCM tissues also contained elevated levels of polyubiquitinated proteins and possessed enhanced 20S-proteasome chymotrypsin-like activities (P < 0.04) as measured in vitro using a fluorogenic substrate. DCM tissues contained activated caspases-9 and -3 (P < 0.001) and reduced expression of the caspase substrate PARP-1 (P < 0.05). Western blotting and immunohistochemistry revealed that DCM tissues contained elevated expression levels of caspase-3-activated DNAse (CAD; P < 0.001), which is a key effector of DNA fragmentation in apoptosis and also contained elevated expression of a potent inhibitor of CAD (ICAD-S; P < 0.01). CONCLUSION Expression of p53 in human DCM is associated with dysregulation of UPS components, which are known to regulate p53 stability. Elevated p53 expression and caspase activation in DCM was not associated with activation of both CAD and its inhibitor, ICAD-S. Our findings are consistent with the concept that apoptosis may be interrupted and therefore potentially reversible in human HF.

Increased toll-like receptor 4 in the myocardium of patients requiring left ventricular assist devices

BACKGROUND Cytokine activation in the myocardium of deteriorating patients with heart failure who undergo left ventricular assist-device (LVAD) implantation has been documented, but the underlying mechanisms remain poorly understood. We hypothesized the innate immune system is activated with expression of Toll-like receptor 4 (TLR4), leading to cytokine activation in these patients. METHODS We used quantitative real-time reverse-transcriptase polymerase chain reaction to measure TLR4, interleukin-1 (IL-1) receptor, IL-1 beta, IL-6, and tumor necrosis factor alpha (TNF-alpha) mRNA expression in myocardial samples from 36 patients. We compared 18 patients who underwent LVAD implantation with 18 patients with less severe heart failure who underwent elective heart transplantation. RESULTS Toll-like receptor 4 expression was 1.69-fold greater (p < 0.05) and IL-1 receptor expression was 3.64-fold greater (p < 0.0001) in the deteriorating patients who required LVADs. Myocardial TNF-alpha (1.71-fold, p < 0.05), IL-6 (2.57-fold, p < 0.005), and IL-1 beta (9.78-fold, p < 0.001) also were increased in the LVAD candidates. Toll-like receptor 4 expression correlated strongly with IL-1 receptor expression (r= 0.75, p < 0.0001) and with IL-1 beta expression in individual patients (r = 0.7, p < 0.0001). Interleukin-1 receptor expression also correlated with IL-1 beta expression (r = 0.78, p < 0.0001) within patients. We found no correlation between TLR4 and either TNF-alpha or IL-6 expression. CONCLUSIONS Patients who required LVAD support showed evidence of innate immune system activation, indicated by an increase in the key effector molecule TLR4 associated with a specific pattern of cytokine expression in the myocardium.

Expression of Follistatin-Related Genes Is Altered in Heart Failure

Follistatins play roles in diverse biological processes including cell proliferation, wound healing, inflammation, and skeletal muscle growth, yet their role in the heart is currently unknown. We have investigated the myocardial expression profile and cellular distribution of follistatin (FST) and the FST-like genes FSTL1 and FSTL3 in the normal and failing heart. Expression was further analyzed in the novel setting of recovery from heart failure in myocardium obtained from patients who received combined mechanical (left ventricular assist device) and pharmacological therapy. Real-time PCR revealed that FSTL1 and FSTL3 expression was elevated in heart failure but returned to normal after recovery. FSTL3 expression levels correlated with molecular markers of disease severity and FSTL1 with the endothelial cell marker CD31, suggesting a potential link with vascularization. FSTL1 levels before treatment correlated with cardiac function after recovery, suggesting initial levels may influence long-term outcome. Immunohistochemistry revealed that FST was primarily localized to fibroblasts and vascular endothelium within the heart, whereas FSTL1 was localized to myocytes, endothelium, and smooth muscle cells and FSLT3 to myocytes and endothelium. Microarray analysis revealed that FST and FSTL1 were associated with extracellular matrix-related and calcium-binding proteins, whereas FSTL3 was associated mainly with cell signaling and transcription. These data show for the first time that elevated myocardial expression of FST-like genes is a feature of heart failure and may be linked to both disease severity and mechanisms underlying recovery, revealing new insight into the pathogenesis of heart failure and offering novel therapeutic targets.

Increased expression of extracellular matrix regulators TIMP1 and MMP1 in deteriorating heart failure

BACKGROUND The authors previously identified and compared alterations in gene expression in the myocardia of patients with deteriorating heart failure who underwent left ventricular assist device (LVAD) implantation with those of patients with stable end-stage failure (ESF). We hypothesized that matrix metalloproteinases (MMPs) and their endogenous inhibitors, the tissue inhibitors of MMPs (TIMPs), would be implicated in the mechanisms that underlie deteriorating heart failure. METHODS Gridded macro-array filters were used to provide a broad overview of MMP and TIMP mRNA expression in heart failure. Precise mRNA levels of TIMP1, MMP1, and beta-spectrin were determined using quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) of myocardial samples from 27 patients with deteriorating heart failure who underwent LVAD implantation, from 17 patients with stable ESF who underwent elective heart transplantation, and from 28 donor organs with good hemodynamic function. RESULTS Gridded macro-arrays analysis of pooled failing heart samples determined that TIMP1 mRNA was the most readily detectable TIMP in failing myocardium. Quantitative RT-PCR showed that expression levels in individual patients were similar in patients with stable ESF (1.00 +/- 0.24, n = 17) and in donor organ samples (1.49 +/- 0.22, n = 28) but were significantly increased in the deteriorating heart failure group (5.38 +/- 0.32, n = 26, p < 0.0001 compared with patients with ESF). Similarly, MMP1 levels did not differ between donor and ESF groups but increased in the deteriorating failure group (6.04 +/- 0.50, n = 27, p < 0.001 compared with the ESF group). Levels of beta-II spectrin were the same in all 3 groups. Both TIMP1 and MMP1 showed positive correlation with each other and with previously determined levels of mRNA for both interleukin-1beta (IL-1beta) and IL-6 in this patient series when considering all patients individually, but neither correlated with tumor necrosis factor alpha. CONCLUSIONS Patients with deteriorating heart failure have increased expression of TIMP1 and MMP1 mRNA. Correlation with pro-inflammatory cytokines suggests common pathways of regulation and potential activation by IL-6 and IL1-beta.

Quality of Life After Removal of Left Ventricular Assist Device for Myocardial Recovery

BACKGROUND Longer term quality of life (QOL) outcome in patients who have had a left ventricular assist device (LVAD) explanted due to myocardial recovery (bridge to recovery, BTR) remains uncertain. This study evaluates the QOL of those patients and compares them to bridge-to-transplant (BTT) and transplanted (Tx) patients. METHODS Anonymized QOL Short Form (SF)-36 questionnaires were sent to a total of 72 patients, including: 14 BTR patients (3.6 +/- 1.9 years since LVAD removal); 29 BTT patients (3.3 +/- 2.3 years since transplantation); and 29 Tx patients (3.8 +/- 0.6 years since transplantation). RESULTS Questionnaires were returned by 78.6%, 79.3% and 56.7% of patients from the BTR, BTT and Tx groups, respectively. In all but two of the domains of the SF-36 questionnaire, scores were significantly better in the BTR group compared with the BTT and Tx groups. Analysis of the two main dimensions and the total SF-36 score between the three groups showed that: (i) physical health dimension tended to be better in BTR (71.9 +/- 21) vs BTT (64.5 +/- 23.2) and Tx (41.4 +/- 48) groups (p = not statistically significant [NS]); (ii) mental health dimension was better in both BTR (78 +/- 16.1) and BTT (71.4 +/- 21.1) groups compared with the Tx group (39.4 +/- 44, p < 0.05); and (iii) total SF-36 score was significantly higher in the BTR and BTT groups compared with the Tx group (76.8 +/- 17.6 and 69 +/- 21.1 vs 41.4 +/- 48, p = NS). CONCLUSIONS BTR patients appear to have better QOL than both BTT and Tx patients. In addition, BTT patients seem to have a better QOL compared with Tx patients, suggesting that placement of ventricular assist devices could improve the physiologic outcome for transplanted patients.

Expression of Extracellular Matrix Genes During Myocardial Recovery From Heart Failure After Left Ventricular Assist Device Support

BACKGROUND Abnormalities in the extracellular matrix (ECM) can occur in heart failure. In this study we analyzed ECM gene expression in patients with advanced dilated cardiomyopathy who did and did not develop sustained myocardial recovery after left ventricular assist device (LVAD) unloading combined with pharmacologic therapy. METHODS Myocardial gene expression of collagens (COL1A1 and COL3A1), fibronectin (FN), matrix metalloproteinases (MMPs 1 to 14), tissue inhibitors of metalloproteinases (TIMPs 1 to 4), connective tissue growth factor (CTGF), transforming growth factor-beta1 (TGF-beta1) and THY1 was measured by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) at LVAD implantation and again at explantation (recovery, n = 11) or transplantation (non-recovery, n = 5). RESULTS The non-recovery group had higher levels of pro-fibrotic markers (COL1A1, TGF-beta1 and THY1) at implantation compared with the recovery group (1.82 +/- 0.74-, 1.81 +/- 0.69- and 3.01 +/- 1.70-fold, respectively; p <or= 0.05). Both recovery and non-recovery groups showed no significant difference in gene expression after treatment, but levels of pro-fibrotic genes (COL1A1, COL3A1, FN and THY1) correlated negatively with post-explant ejection fraction in the recovery group. Of all genes analyzed only TIMP4 showed a significant change, with expression reduced during recovery (0.55 +/- 0.25-fold at explant vs implant, p = 0.001). All other genes showed complex patterns between individuals with both increased and decreased expression of pro-fibrotic markers, MMPs and TIMPs in recovery patients. CONCLUSIONS Patients who did not recover had higher myocardial expression of pro-fibrotic genes at LVAD implantation, and in recovered patients higher levels at explant were negatively associated with subsequent ejection fraction. However, individual patients showed complex expression patterns and a decrease in pro-fibrotic markers was not required for recovery.

Decreased cardiac activity of AMP deaminase in subjects with the AMPD1 mutation--a potential mechanism of protection in heart failure.

OBJECTIVES Possession of the C34T (Glu12Stop) nonsense mutation in the AMP-deaminase 1 (AMPD1) gene has been shown to be associated with improved prognosis in heart failure and ischemic heart disease. The most likely event leading to these clinical effects is a reduced capacity of the AMP deamination pathway and increased production of cardio-protective adenosine. However, since AMPD1 is predominantly expressed in skeletal muscle, the protective effects could be related not only to local cardiac changes, but also to a systemic mechanism. In the present study we evaluated the effect of the C34T mutation on cardiac AMP-deaminase activity and on the systemic changes in adenosine production. METHODS The presence of the C34T mutation was assayed by single-stranded conformational polymorphism (SSCP). Analysis of the AMPD1 genotype and measurement of enzyme activities was performed on 27 patients with heart failure (HF). In addition, blood adenosine concentration was measured by liquid chromatography/mass spectrometry (LC/MS) in 21 healthy subjects with established AMPD1 genotype at rest and following exhaustive exercise. RESULTS Cardiac AMP-deaminase activity in heterozygotes (C/T) was 0.59+/-0.02 nmol/min/g wet wt-about half of the activity found in normal wild-type (C/C) individuals (1.06+/-0.09 nmol/min/g wet wt, P=0.003). There were no significant differences in the activities of any other enzymes between subjects with the C/T or C/C genotype. Resting venous blood adenosine concentration was similar in subjects with C/C, C/T and homozygous for the mutated allele (T/T) genotype. Following exercise, a significant increase in adenosine was observed in T/T subjects (by 0.013+/-0.009 micromol/l, P=0.035) but not in C/C (0.003+/-0.009 micromol/l) or C/T (-0.002+/-0.011 micromol/l). CONCLUSIONS Our findings indicate that the C34T mutation of AMPD1 leads to a decrease in cardiac enzyme activity of AMP-deaminase without changes in any other adenosine-regulating enzymes, highlighting the importance of local cardiac metabolic changes. Systemic (blood) changes in adenosine concentration were apparent only in homozygous subjects and therefore may play a relatively small part in cardio-protection.

Overexpression of the transcription factor Hand1 causes predisposition towards arrhythmia in mice

Elevated levels of the cardiac transcription factor Hand1 have been reported in several adult cardiac diseases but it is unclear whether this change is itself maladaptive with respect to heart function. To test this possibility, we have developed a novel, inducible transgenic system, and used it to overexpress Hand1 in adult mouse hearts. Overexpression of Hand1 in the adult mouse heart leads to mild cardiac hypertrophy and a reduction in life expectancy. Treated mice show no significant fibrosis, myocyte disarray or congestive heart failure, but have a greatly reduced threshold for induced ventricular tachycardia, indicating a predisposition to cardiac arrhythmia. Within 48 h, they show a significant loss of connexin43 protein from cardiac intercalated discs, with increased intercalated disc beta-catenin expression at protein and RNA levels. These changes are sustained during prolonged Hand1 overexpression. We propose that cardiac overexpression of Hand1 offers a useful mouse model of arrhythmogenesis and elevated HAND1 may provide one of the molecular links between the failing heart and arrhythmia.