Value of SERCA2a as a Biomarker for the Identification of Patients with Heart Failure Requiring Circulatory Support.

BACKGROUND: Heart failure (HF) alters the nucleo-cytoplasmic transport of cardiomyocytes and reduces SERCA2a levels, essential for intracellular calcium homeostasis. We consider in this study whether the molecules involved in these processes can differentiate those patients with advanced HF and the need for mechanical circulatory support (MCS) as a bridge to recovery or urgent heart transplantation from those who are clinically stable and who are transplanted in an elective code. MATERIAL AND METHOD: Blood samples from 29 patients with advanced HF were analysed by ELISA, and the plasma levels of Importin5, Nucleoporin153 kDa, RanGTPase-Activating Protein 1 and sarcoplasmic reticulum Ca2+ ATPase were compared between patients requiring MCS and those patients without a MCS need prior to heart transplantation. RESULTS: SERCA2a showed significantly lower levels in patients who had MCS compared to those who did not require it (0.501 ± 0.530 ng/mL vs. 1.123 ± 0.661 ng/mL; p = 0.01). A SERCA2a cut-off point of 0.84 ng/mL (AUC 0.812 ± 0.085, 95% CI: 0.646-0.979; p = 0.004) provided a 92% sensitivity, 62% specificity, 91% negative predictive value and 67% positive predictive value. CONCLUSIONS: In this cohort, patients with advanced HF and a need for MCS have shown significantly lower levels of SERCA2a as compared to stable patients without a need for MCS prior to heart transplantation. This is a small study with preliminary findings, and larger-powered dedicated studies are required to confirm and validate these results.

Prognostic value and clinical predictors of intramyocardial hemorrhage measured by CMR T2* sequences in STEMI.

Recent studies show that microvascular injury consists of microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH). In patients with reperfused ST-segment elevation myocardial infarction (STEMI) quantitative assessment of IMH with T2* cardiovascular magnetic resonance imaging (CMR) appears to be useful in evaluation of microvascular damage. The current study aimed to investigate feasibility of this approach and to correlate IMH with clinical and CMR parameters. A single center observational cohort study was performed in reperfused STEMI patients with CMR examination 7 days (IQR: 5 to 8 days) after percutaneous coronary intervention. Infarct size (IS) and MVO were evaluated in short-axis late gadolinium enhancement sequences and IMH with whole LV volume T2* mapping sequences. Of the 94 patients, MVO was identified in 52% of patients and the median size of MVO was 3% of LV mass (IQR: 1.5 to 5.4%). IMH was present in 28% of patients and the median size of IMH was 1.1% of LV mass (IQR: 0.5 to 2.9%). IMH extent was independently associated with anterior myocardial infarction (p = 0.022) and thrombectomy (p = 0.049). IMH was correlated with MVO (R = 0.62, p < 0.001), necrosis (R = 0.58, p < 0.001) and LVEF (R = -0.21, p = 0.04). Patients with IMH presented higher incidence of MACE events, independently of LVEF (p = 0.022). T2* mapping is a novel imaging approach that proves useful to asses IMH in the setting of reperfused STEMI. T2* IMH extent was associated with anterior infarction and thrombectomy. T2* IMH was associated with higher incidence of MACE events regardless preserved or reduced LVEF.

Homocysteine and long-term recurrent infarction following an acute coronary syndrome.

BACKGROUND: There are no well-established predictors of recurrent ischemic coronary events after an acute coronary syndrome (ACS). Higher levels of homocysteine have been reported to be associated with an increased atherosclerotic burden. The primary endpoint was to assess the relationship between homocysteine at discharge and very long-term recurrent myocardial infarction (MI). METHODS: 1306 consecutive patients with ACS were evaluated (862 with non-ST-segment elevation ACS [NSTEACS] and 444 with ST-segment elevation myocardial infarction [STEMI]) discharged from October 2000 to June 2003 in a single teaching-center. The relationship between homocysteine at discharge and recurrent MI was evaluated through bivariate negative binomial regression accounting for mortality as a competitive event. RESULTS: The mean age was 66.8 ± 12.4 years, 69.1% were men, and 32.2% showed prior diabetes mellitus. Most of the patients were admitted for an NSTEACS (66.0%). The median (interquartile range) GRACE risk score, Charlson comorbidity index, and homocysteine were 144 (122-175) points, 1 (1-2) points, and 11.9 (9.3-15.6) µmol/L, respectively. In-hospital revascularization was performed in 26.3% of patients. At a median follow-up of 9.7 (4.5-15.1) years, 709 (54.3%) deaths were registered and 779 recurrent MI in 478 (36.6%) patients. The rates of recurrent MI were higher in patients in the upper homocysteine quartiles (p < 0.001). After a multivariate adjustment, homocysteine along its continuum remained almost linearly associated with a higher risk of recurrent MI (p = 0.001) and all-cause mortality (p < 0.001). CONCLUSIONS: In patients with ACS, higher homocysteine levels identified those at a higher risk of recurrent MI at very long-term follow-up.

Lipoprotein(a) and long-term recurrent infarction after an episode of ST-segment elevation acute myocardial infarction.

BACKGROUND: In established ischemic heart disease, the relationship between lipoprotein(a) and new cardiovascular events showed contradictory results. Our aim was to assess the relationship between lipoprotein(a) and very long-term recurrent myocardial infarction (MI) after an index episode of ST-segment elevation acute myocardial infarction (STEMI). METHODS: We included 435 consecutive STEMI patients discharged from October 2000 to June 2003 in a single teaching center. The relationship between lipoprotein(a) at discharge and recurrent MI was evaluated through negative binomial regression and Cox regression analysis. RESULTS: The mean age was 65 years (55-74 years), 25.5% were women, 34.7% were diabetic, and 66% had a MI of anterior location. Fibrinolysis, rescue, or primary angioplasty was performed in 215 (49.4%), 19 (4.4%), and 18 (4.1%) patients, respectively. The median lipoprotein(a) was 30.4 mg/dL (12-59.4 mg/dL). After a median follow-up of 9.6 years (4.1-15 years), 180 (41.4%) deaths and 187 MI in 133 (30.6%) patients were recorded. After a multivariate adjustment, the risk gradient of lipoprotein(a) showed a neutral effect along most of the continuum and only extreme higher values identified those at higher risk of recurrent MI (P = 0.020). Those with lipoprotein(a) values >95th percentile (≥135 mg/dL) showed a higher risk of recurrent MI (incidence rate ratio, 2.34; 95% confidence interval, 1.37-4.02; P = 0.002). Lipoprotein(a) was not related to the risk of mortality (P = 0.245). CONCLUSIONS: After an episode of STEMI, only extreme high values of lipoprotein(a) were associated with an increased risk of long-term recurrent MI.

Plasma CD5L and non-invasive diagnosis of acute heart rejection.

BACKGROUND: Acute rejection is one of the most important direct contributors to mortality after heart transplantation. Advances in the development of novel non-invasive approaches for the early identification of allograft rejection are necessary. We conducted a non-targeted proteome characterization focused on identifying multiple plasmatic protein differences to evaluate their diagnostic accuracy for rejection episodes. METHODS: We included consecutive plasma samples from transplant recipients undergoing routine endomyocardial biopsies. A liquid chromatography-tandem mass spectrometry analysis using isobaric tags (tandem mass tag 10-plex) was performed and concentrations of CD5L were validated using a specific sandwich enzyme-linked immunosorbent assay. RESULTS: A total of 17 altered proteins were identified as potential markers for detecting heart transplant rejection, most involved in inflammation and immunity. CD5L, an apoptosis inhibitor expressed by macrophages, showed the best results in the proteomic analysis (n = 30). We confirm this finding in a larger patient cohort (n = 218), obtaining a great diagnostic capacity for clinically relevant rejection (≥Grade 2R: area under the curve = 0.892, p < 0.0001) and preserving the accuracy at mild rejection (Grade 1R: area under the curve = 0.774, p < 0.0001). CD5L was a strong independent predictor, with an odds ratio of 14.74 (p < 0.0001), for the presence of rejection. CONCLUSIONS: Episodes of acute cardiac allograft rejection are related to significant changes in a key inhibitor of apoptosis in macrophages, CD5L. Because of its precision to detect acute cellular rejection, even at mild grade, we propose CD5L as a potential candidate to be included in the studies of molecule combination panel assays. This finding could contribute to improving the diagnostic and preventive methods for the surveillance of cardiac transplanted patients.

XPO1 Gene Therapy Attenuates Cardiac Dysfunction in Rats with Chronic Induced Myocardial Infarction.

Transcriptomic signature of XPO1 was highly expressed and inversely related to left ventricular function in ischemic cardiomyopathy patients. We hypothesized that treatment with AAV9-shXPO1 attenuates left ventricular dysfunction and remodeling in a myocardial infarction rat model. We induced myocardial infarction by coronary ligation in Sprague-Dawley rats (n = 10), which received AAV9-shXPO1 (n = 5) or placebo AAV9-scramble (n = 5) treatment. Serial echocardiographic assessment was performed throughout the study. After myocardial infarction, AAV9-shXPO1-treated rats showed partial recovery of left ventricular fractional shortening (16.8 ± 2.8 vs 24.6 ± 4.1%, P < 0.05) and a maintained left ventricular dimension (6.17 ± 0.95 vs 4.70 ± 0.93 mm, P < 0.05), which was not observed in non-treated rats. Furthermore, lower levels of EXP-1 (P < 0.05) and lower collagen fibers and fibrosis in cardiac tissue were observed. However, no differences were found in the IL-6 or TNFR1 plasma levels of the myocardium of AAV9-shXPO1 rats. AAV9-shXPO1 administration attenuates cardiac dysfunction and remodeling in rats after myocardial infarction, producing the gene silencing of XPO1.

Circulating Sphingosine-1-Phosphate as A Non-Invasive Biomarker of Heart Transplant Rejection.

Accumulating evidence has confirmed that the expression of sarcoplasmic reticulum calcium ATPase 2a (SERCA2a) is downregulated in heart failure and cardiac allograft rejection. Although many SERCA2a-related genes and proteins involved in the regulation of myocardial Ca2+ fluxes have been explored, its related metabolites remain poorly studied. Our main objective was to identify circulating SERCA2a-related metabolites altered in cardiac allograft rejection and to determine whether these could serve as non-invasive biomarkers. Sixty plasma samples from adult heart transplant were included in a metabolomic analysis. Sphingosine-1 phosphate (S1P), metabolite closely related with SERCA, were increased in patients with cardiac rejection (p < 0.0001). S1P discriminated between patients with and without rejection: normal grafts vs. all rejecting grafts (AUC = 0.911, p < 0.0001), normal grafts vs. Grade 1 R (AUC = 0.819, p < 0.01), Grade 2 R (AUC = 0.911, p < 0.0001), Grade 3 R (AUC = 0.996, p < 0.0001). In addition, we found changes in key enzymes and receptors of S1P pathway analysed on explanted hearts from heart failure patients. This preliminary study reveals that circulating S1P determination could be a novel approach to detect cardiac rejection, showing a robust capability for detection that improves gradually with the severity of rejection. These alterations could be relevant to better understand the involvement of calcium regulation on the pathophysiology of rejection.

The altered expression of autophagy-related genes participates in heart failure: NRBP2 and CALCOCO2 are associated with left ventricular dysfunction parameters in human dilated cardiomyopathy.

This study aimed to analyze changes in the expression of autophagy- and phagocytosis-related genes in patients with dilated cardiomyopathy (DCM), especially in relation to left ventricular (LV) dysfunction. Furthermore, transmission electron microscopy of the diseased tissue was carried out to investigate if the gene expression changes are translated into ultrastructural alterations. LV tissue samples from patients with DCM (n = 13) and from controls (CNT; n = 10) were analyzed by RNA-sequencing, whereupon the altered expression (P < 0.05) of 13 autophagy- and 3 phagocytosis-related genes was observed. The expression changes of the autophagy-related genes NRBP2 and CALCOCO2 were associated with cardiac dysfunction and remodeling (P < 0.05). The affected patients had a higher activity of these degradation processes, as evidenced by the greater number of autophagic structures in the DCM tissue (P < 0.001). Differences in the ultrastructural distribution were also found between the DCM and CNT tissues. These results show that in patients with DCM, the altered expression of NRBP2 and CALCOCO2 is related to LV dysfunction and remodeling. Clarification of the molecular mechanisms of cardiac autophagy would help in the future development of therapies to improve LV performance.

ASB1 differential methylation in ischaemic cardiomyopathy: relationship with left ventricular performance in end-stage heart failure patients.

AIMS: Ischaemic cardiomyopathy (ICM) leads to impaired contraction and ventricular dysfunction, causing high rates of morbidity and mortality. Epigenomics allows the identification of epigenetic signatures in human diseases. We analyse the differential epigenetic patterns of the ASB gene family in ICM patients and relate these alterations to their haemodynamic and functional status. METHODS AND RESULTS: Epigenomic analysis was carried out using 16 left ventricular (LV) tissue samples, eight from ICM patients undergoing heart transplantation and eight from control (CNT) subjects without cardiac disease. We increased the sample size up to 13 ICM and 10 CNT for RNA sequencing and to 14 ICM for pyrosequencing analyses. We found a hypermethylated profile (cg11189868) in the ASB1 gene that showed a differential methylation of 0.26Δß (P = 0.016). This result was validated by a pyrosequencing technique (0.23Δß, P = 0.048). Notably, the methylation pattern was strongly related to LV ejection fraction (r = -0.849, P = 0.008), stroke volume (r = -0.929, P = 0.001), and end-systolic and diastolic LV diameters (r = -0.743, P = 0.035 for both). ASB1 showed a down-regulation in messenger RNA levels (-1.2-fold, P = 0.039). CONCLUSIONS: Our findings link a specific ASB1 methylation pattern to LV structure and performance in end-stage ICM, opening new therapeutic opportunities and providing new insights regarding which is the functionally relevant genome in the ischaemic failing myocardium.

Myocardium of patients with dilated cardiomyopathy presents altered expression of genes involved in thyroid hormone biosynthesis.

BACKGROUND: The association between dilated cardiomyopathy (DCM) and low thyroid hormone (TH) levels has been previously described. In these patients abnormal thyroid function is significantly related to impaired left ventricular (LV) function and increased risk of death. Although TH was originally thought to be produced exclusively by the thyroid gland, we recently reported TH biosynthesis in the human ischemic heart. OBJECTIVES: Based on these findings, we evaluated whether the genes required for TH production are also altered in patients with DCM. METHODS: Twenty-three LV tissue samples were obtained from patients with DCM (n = 13) undergoing heart transplantation and control donors (n = 10), and used for RNA sequencing analysis. The number of LV DCM samples was increased to 23 to determine total T4 and T3 tissue levels by ELISA. RESULTS: We found that all components of TH biosynthesis are expressed in human dilated heart tissue. Expression of genes encoding thyroperoxidase (-2.57-fold, P < 0.05) and dual oxidase 2 (2.64-fold, P < 0.01), the main enzymatic system of TH production, was significantly altered in patients with DCM and significantly associated with LV remodeling parameters. Thyroxine (T4) cardiac tissue levels were significantly increased (P < 0.01), whilst triiodothyronine (T3) levels were significantly diminished (P < 0.05) in the patients. CONCLUSIONS: Expression of TH biosynthesis machinery in the heart and total tissue levels of T4 and T3, are altered in patients with DCM. Given the relevance of TH in cardiac pathology, our results provide a basis for new gene-based therapeutic strategies for treating DCM.

Intercalated disc in failing hearts from patients with dilated cardiomyopathy: Its role in the depressed left ventricular function.

Alterations in myocardial structure and reduced cardiomyocyte adhesions have been previously described in dilated cardiomyopathy (DCM). We studied the transcriptome of cell adhesion molecules in these patients and their relationships with left ventricular (LV) function decay. We also visualized the intercalated disc (ID) structure and organization. The transcriptomic profile of 23 explanted LV samples was analyzed using RNA-sequencing (13 DCM, 10 control [CNT]), focusing on cell adhesion genes. Electron microscopy analysis to visualize ID structural differences and immunohistochemistry experiments of ID proteins was also performed. RT-qPCR and western blot experiments were carried out on ID components. We found 29 differentially expressed genes, most of all, constituents of the ID structure. We found that the expression of GJA3, DSP and CTNNA3 was directly associated with LV ejection fraction (r = 0.741, P = 0.004; r = 0.674, P = 0.011 and r = 0.565, P = 0.044, respectively), LV systolic (P = 0.003, P = 0.003, P = 0.028, respectively) and diastolic dimensions (P = 0.006, P = 0.001, P = 0.025, respectively). Electron microscopy micrographs showed a reduced ID convolution index and immunogold labeling of connexin 46 (GJA gene), desmoplakin (DSP gene) and catenin α-3 (CTNNA3 gene) proteins in DCM patients. Moreover, we observed that protein and mRNA levels analyzed by RT-qPCR of these ID components were diminished in DCM group. In conclusion, we report significant gene and protein expression changes and found that the ID components GJA3, DSP and CTNNA3 were highly related to LV function. Microscopic observations indicated that ID is structurally compromised in these patients. These findings give new data for understanding the ventricular depression that characterizes DCM, opening new therapeutic perspectives for these critically diseased patients.

SERCA2a: A potential non-invasive biomarker of cardiac allograft rejection.

BACKGROUND: The detection of heart transplant rejection by non-invasive methods remains a major challenge. Despite the well-known importance of the study of sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) in the heart, its role as a rejection marker has never been analyzed. Our objective in this study was to determine whether circulating SERCA2a could be a good marker of cardiac rejection. METHODS: We collected 127 consecutive endomyocardial biopsies (EMBs) and serum samples from adult heart transplant recipients (49 without allograft rejection and 78 with the diagnosis of biopsy allograft rejection, including 48 Grade 1R, 21 Grade 2R and 9 Grade 3R). Serum concentrations of SERCA2a were determined using a specific sandwich enzyme-linked immunosorbent assay. We also analyzed SERCA2a expression changes on EMBs using immunofluorescence. RESULTS: SERCA2a cardiac tissue and serum levels were decreased in patients with cardiac rejection (p < 0.0001). A receiver-operating characteristic analysis showed that SERCA2a strongly discriminated between patients with and without allograft rejection: normal grafts vs all rejecting grafts (AUC = 0.804); normal grafts vs Grade 1R (AUC = 0.751); normal grafts vs Grade 2R (AUC = 0.875); normal grafts vs Grade 3R (AUC = 0.922); normal grafts vs Grade 2R and 3R (AUC = 0.889), with p < 0.0001 for all comparisons. CONCLUSIONS: We demonstrated that changes in SERCA2a cardiac tissue and serum levels occur in cardiac allograft rejection. Our findings suggest that SERCA2a concentration assessment may be a relatively simple, non-invasive test for heart transplant rejection, showing a strong capability for detection that improves progressively as rejection grades increase.

Thyroid hormone biosynthesis machinery is altered in the ischemic myocardium: An epigenomic study.

BACKGROUND: Abnormal thyroid hormone (TH) metabolism is significantly associated with impaired left ventricular (LV) function and death. Although TH was traditionally thought to be produced exclusively by the thyroid gland, an increasing number of studies report TH production in other tissues. Based on these findings, we evaluated whether the genes required for TH biosynthesis are expressed in the human heart, and whether their expression is altered in patients with ischemic cardiomyopathy (ICM) and is related to epigenetic variations. METHODS: Twenty-three LV tissue samples were obtained from ICM patients (n=13) undergoing heart transplantation and control donors (n=10) for RNA sequencing analysis. We increased the LV samples to 27 for the ELISA determination of total T4 and T3 tissue levels. For epigenomic studies, 850K Infinium MethylationEPIC BeadChip platform was performed. RESULTS: Using RNA-sequencing, we displayed the expression levels of all components required for TH biosynthesis in human heart tissue. We observed significantly altered expression of genes encoding thyroperoxidase (TPO; -2.48-fold, P<0.05) and dual oxidase 2 (2.83-fold, P<0.05), the main enzymatic system of TH production, and significant relationships between their altered expression and LV remodeling parameters. In addition, epigenetic analysis revealed a differential methylation pattern in TPO, and triiodothyronine tissue levels were significantly decreased (P<0.01). CONCLUSIONS: These results showed that the human heart expresses the TH biosynthesis machinery, being altered its main enzymatic system in patients with ICM. Given the relevance of TH in cardiac pathology, our results provide a foundation for new therapeutic approaches based on TPO for treating ICM.

New Altered Non-Fibrillar Collagens in Human Dilated Cardiomyopathy: Role in the Remodeling Process.

BACKGROUND: In dilated cardiomyopathy (DCM), cardiac failure is accompanied by profound alterations of extracellular matrix associated with the progression of cardiac dilation and left ventricular (LV) dysfunction. Recently, we reported alterations of non-fibrillar collagen expression in ischemic cardiomyopathy linked to fibrosis and cardiac remodeling. We suspect that expression changes in genes coding for non-fibrillar collagens may have a potential role in DCM development. OBJECTIVES: This study sought to analyze changes in the expression profile of non-fibrillar collagen genes in patients with DCM and to examine relationships between cardiac remodeling parameters and the expression levels of these genes. METHODS AND RESULTS: Twenty-three human left ventricle tissue samples were obtained from DCM patients (n = 13) undergoing heart transplantation and control donors (n = 10) for RNA sequencing analysis. We found increased mRNA levels of six non-fibrillar collagen genes, such as COL4A5, COL9A1, COL21A1, and COL23A1 (P < 0.05 for all), not previously described in DCM. Protein levels of COL8A1 and COL16A1 (P < 0.05 for both), were correspondingly increased. We also identified TGF-ß1 significantly upregulated and related to both COL8A1 and COL16A1. Interestingly, we found a significant relationship between LV mass index and the gene expression level of COL8A1 (r = 0.653, P < 0.05). CONCLUSIONS: In our research, we identified new non-fibrillar collagens with altered expression in DCM, being COL8A1 overexpression directly related to LV mass index, suggesting that they may be involved in the progression of cardiac dilation and remodeling.

TRPM7 is down-regulated in both left atria and left ventricle of ischaemic cardiomyopathy patients and highly related to changes in ventricular function.

AIMS: The kinase ion channel transient receptor potential melastatin 7 (TRPM7) is considered a modulator of cardiac fibrosis progression; nevertheless, we lack of studies analysing its role in human ischaemic cardiomyopathy (ICM). Our objective was to analyse the expression of genes encoding cardiac ion channels in human ICM, focusing on the alterations in mRNA levels of TRPM7 and its relationship with changes in the ventricular function. METHODS AND RESULTS: RNA-sequencing was carried out in 13 left ventricular (LV) samples of patients with ICM compared with a control group (n = 10). The analysis revealed a total of 25 ion channel genes differentially expressed. We performed an RTqPCR analysis of the TRPM7 mRNA in LV and left atrial samples and found that it was down-regulated in both cavities (-1.43-fold and -1.52-fold, respectively). Atrial TRPM7 mRNA levels showed an excellent and inverse relationships with the depressed ejection fraction (r = -0.724, P = 0.042) and with the mitral A wave (r = -0.938, P = 0.006). CONCLUSIONS: We report the down-regulation of TRPM7 in tissue samples from both left atria and left ventricle in patients with ICM. We found an inverse relationship between both cardiac chambers mRNA levels with LV dysfunction, suggesting an important role of TRPM7 in the left atrial and LV functional depression found in this cardiomyopathy.

Protein Inhibitor of NOS1 Plays a Central Role in the Regulation of NOS1 Activity in Human Dilated Hearts.

An essential factor for the production of nitric oxide by nitric oxide synthase 1 (NOS1), major modulator of cardiac function, is the cofactor tetrahydrobiopterin (BH4). BH4 is regulated by GTP cyclohydrolase 1, the rate-limiting enzyme in BH4 biosynthesis which catalyses the formation of dihydroneopterin 3'triphosfate from GTP, producing BH4 after two further steps catalyzed by 6-pyruvoyltetrahydropterin synthase and sepiapterin reductase. However, there are other essential factors involved in the regulation of NOS1 activity, such as protein inhibitor of NOS1 (PIN), calmodulin, heat shock protein 90, and NOS interacting protein. All these molecules have never been analysed in human non-ischemic dilated hearts (DCM). In this study we demonstrated that the upregulation of cardiac NOS1 is not accompanied by increased NOS1 activity in DCM, partly due to the elevated PIN levels and not because of alterations in biopterin biosynthesis. Notably, the PIN concentration was significantly associated with impaired ventricular function, highlighting the importance of this NOS1 activity inhibitor in Ca(2+) homeostasis. These results take a central role in the current list of targets for future studies focused on the complex cardiac dysfunction processes through more efficient harnessing of NOS1 signalling.

New Cell Adhesion Molecules in Human Ischemic Cardiomyopathy. PCDHGA3 Implications in Decreased Stroke Volume and Ventricular Dysfunction.

BACKGROUND: Intercalated disks are unique structures in cardiac tissue, in which adherens junctions, desmosomes, and GAP junctions co-localize, thereby facilitating cardiac muscle contraction and function. Protocadherins are involved in these junctions; however, their role in heart physiology is poorly understood. We aimed to analyze the transcriptomic profile of adhesion molecules in patients with ischemic cardiomyopathy (ICM) and relate the changes uncovered with the hemodynamic alterations and functional depression observed in these patients. METHODS AND RESULTS: Twenty-three left ventricular tissue samples from patients diagnosed with ICM (n = 13) undergoing heart transplantation and control donors (CNT, n = 10) were analyzed using RNA sequencing. Forty-two cell adhesion genes involved in cellular junctions were differentially expressed in ICM myocardium. Notably, the levels of protocadherin PCDHGA3 were related with the stroke volume (r = -0.826, P = 0.003), ejection fraction (r = -0.793, P = 0.004) and left ventricular end systolic and diastolic diameters (r = 0.867, P = 0.001; r = 0.781, P = 0.005, respectively). CONCLUSIONS: Our results support the importance of intercalated disks molecular alterations, closely involved in the contractile function, highlighting its crucial significance and showing gene expression changes not previously described. Specifically, altered PCDHGA3 gene expression was strongly associated with reduced stroke volume and ventricular dysfunction in ICM, suggesting a relevant role in hemodynamic perturbations and cardiac performance for this unexplored protocadherin.

Human Ischemic Cardiomyopathy Shows Cardiac Nos1 Translocation and its Increased Levels are Related to Left Ventricular Performance.

The role of nitric oxide synthase 1 (NOS1) as a major modulator of cardiac function has been extensively studied in experimental models; however, its role in human ischemic cardiomyopathy (ICM) has never been analysed. Thus, the objectives of this work are to study NOS1 and NOS-related counterparts involved in regulating physiological function of myocyte, to analyze NOS1 localisation, activity, dimerisation, and its relationship with systolic function in ICM. The study has been carried out on left ventricular tissue obtained from explanted human hearts. Here we demonstrate that the upregulation of cardiac NOS1 is not accompanied by an increase in NOS activity, due in part to the alterations found in molecules involved in the regulation of its activity. We observed partial translocation of NOS1 to the sarcolemma in ischemic hearts, and a direct relationship between its protein levels and systolic ventricular function. Our findings indicate that NOS1 may be significant in the pathophysiology of human ischemic heart disease with a preservative role in maintaining myocardial homeostasis.

Patients with Dilated Cardiomyopathy and Sustained Monomorphic Ventricular Tachycardia Show Up-Regulation of KCNN3 and KCNJ2 Genes and CACNG8-Linked Left Ventricular Dysfunction.

AIMS: Disruptions in cardiac ion channels have shown to influence the impaired cardiac contraction in heart failure. We sought to determine the altered gene expression profile of this category in dilated cardiomyopathy (DCM) patients and relate the altered gene expression with the clinical signs present in our patients, such as ventricular dysfunction and sustained monomorphic ventricular tachycardia (SMVT). METHODS AND RESULTS: Left ventricular (LV) tissue samples were used in RNA-sequencing technique to elucidate the transcriptomic changes of 13 DCM patients compared to controls (n = 10). We analyzed the differential gene expression of cardiac ion channels, and we found a total of 34 altered genes. We found that the calcium channel CACNG8 mRNA and protein levels were down-regulated and highly and inversely related with LV ejection fraction (LVEF) (r = -0.78, P<0.01). Furthermore, the potassium channels KCNN3 and KCNJ2 mRNA and protein levels were up-regulated and showed also a significant and inverse correlation with LVEF (r = -0.61, P<0.05; r = -0.60, P<0.05) in patients with SMVT. CONCLUSION: A broad set of deregulated genes have been identified by RNA-sequencing technique. The relationship of CACNG8, KCNN3 and KCNJ2 with LVEF, and the up-regulation of KCNN3 and KCNJ2 in all patients with SMVT, irrespective of CACNG8 expression, suggest a significant role for these three ion flux related genes in the LV dysfunction present in this cardiomyopathy and an important relationship between KCNN3 and KCNJ2 up-regulation and the presence of SMVT.