Pressure overload and volume overload-induced chronic heart failure are associated with characteristic left ventricular myocardial proteomic alterations

Introduction

Hemodynamic overload induces pathological remodeling of the left ventricle (LV) and eventually heart failure (HF). The two types of chronic hemodynamic stress, namely pressure overload (PO) and volume overload (VO) evoke characteristically different functional and structural alterations in the myocardium. Nevertheless, whether PO- and VO-induced HF are also associated with distinct LV proteomic alterations has not been investigated yet.

Aim

Hence, we thought to perform a proteomic analysis on LV myocardial samples from rat models of PO- and VO-induced HF.

Methods

PO–induced HF was evoked by transverse aortic constriction (TAC). VO–induced HF was established by creating an aortocaval fistula (ACF). Age-matched sham-operated animals served as controls for TAC (ShamT) and ACF (ShamA), respectively. Pressure-volume (P-V) analysis, echocardiography, histology and quantitative real-time PCR were carried out to provide a detailed characterization of the two HF models. Peptides obtained via the digestion of myocardial proteins with trypsin and LysC were labeled with isobaric tags (TMT16) and measured with LC-MS/MS in a bottom-up explorative proteomic approach. Differential expression and gene ontology enrichment analysis (GO:BP) was carried out on summarized protein reporter ion intensities.

Results

In both the TAC and ACF groups, presence of typical signs and symptoms of HF (dyspnea at rest, fatigue, ascites) increased lung-to-tibial length ratio and elevated LV natriuretic peptide mRNA expression levels confirmed the development of advanced HF. Furthermore, the TAC model was associated with massive wall thickening, concentric LV hypertrophy (LVH), marked interstitial fibrosis and substantially impaired active relaxation and passive filling (slope of end-diastolic P-V relationship: 0.103±0.015 vs. 0.023±0.003mmHg/μl, TAC vs. ShamT, P<0.001). In contrast, the ACF model was predominantly characterized by LV dilatation, eccentric LVH, moderate fibrosis and severely reduced LV contractility (slope of end-systolic P-V relationship: 0.5±0.1 vs. 2.3±0.3mmHg/μl, ACF vs. ShamA, P<0.001). Proteomic analysis revealed that out of the 4691 identified and quantified proteins, 1404 and 913 have shown upregulation, while 1359 and 886 downregulation in the TAC and ACF groups respectively compared to their corresponding sham groups. GO:BP analysis has indicated that the downregulation of mitochondrion organization, ATP metabolic processes and oxidative phosphorylation and the upregulation of actin cytoskeleton organization were the most profound alterations in the TAC model. In contrast, the ACF model was associated with robust downregulation of fatty acid oxidation and upregulation of endocytosis, defense and immune response on the proteomic level.

Conclusions

PO and VO-induced advanced HF are not only associated with characteristically different functional and structural remodeling but also with distinct LV proteomic alterations.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Research, Development and Innovation Office (NKFIH) of Hungary

Pharmacological selectivity of SGLT2 inhibitors and cardiovascular outcomes in patients with type 2 diabetes: a meta-analysis

Background

Sodium-glucose cotransporter 2 (SGLT2) inhibitors reduce major adverse cardiovascular events (MACE) in patients with type 2 diabetes mellitus. However, SGLT2 inhibitors show great variance in pharmacological selectivity to SGLT2 over SGLT1. Reduced functional capacity of SGLT1 is associated with lower risk of heart failure development and mortality in humans. Yet, the clinical relevance of additional pharmacological SGLT1 inhibition is unclear.

Purpose

To assess whether additional pharmacological SGLT1 blockade adds further benefits to SGLT2 inhibition.

Methods

In this preregistered meta-analysis, we included randomized placebo-controlled cardiovascular outcome trials (CVOTs) of SGLT2 inhibitors assessing MACE (composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke) in patients with type 2 diabetes. Hazard ratios (HRs) and 95% confidence intervals (CIs) of prespecified clinical endpoints were pooled using a random-effects model. Interactions were assessed according to low versus high pharmacological SGLT2 selectivity of the given medication. Mixed-effects meta-regression analysis was performed to quantify correlation between pharmacological SGLT2:SGLT1 selectivity ratio and clinical outcomes.

Results

A total of 6 independent CVOTs comprising 57553 type 2 diabetic patients (mean age 64.6±7.9 years; 36769 [63.9%] men) were included. Overall, SGLT2 inhibitors significantly reduced risk of adverse cardiovascular and renal outcomes, but had no significant impact on the risk of fatal and nonfatal stroke compared with placebo (HR, 0.92; 95% CI, 0.77–1.10; p=0.36; I2=63%). Agents with clinically relevant SGLT1 inhibitory effect (sotagliflozin, canagliflozin) significantly reduced the risk of stroke (HR, 0.78; 95% CI, 0.64–0.94) compared with placebo, whereas those with high SGLT2 selectivity did not (HR, 1.06; 95% CI, 0.92–1.22), yielding a significant interaction (p=0.018). The difference was also significant in patients with estimated glomerular filtration rate (eGFR) lower than 60 mL/min/1.73 m2 (p=0.047). Meta-regression indicated that lower SGLT2:SGLT1 pharmacological selectivity ratio was associated with lower risk of stroke (pseudo-R2=78%; p=0.011), which was evident even after adjusting for baseline eGFR values (p=0.047). Pharmacological selectivity of SGLT2 inhibitors had no significant impact on any other assessed clinical outcomes, including hospitalization for heart failure and all-cause death.

Conclusion

These hypothesis-generating results indicate that targeting SGLT1 in addition to SGLT2 inhibition might constitute a new avenue for stroke risk reduction in patients with type 2 diabetes. Further confirmatory studies are needed.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This project was supported by grants from the National Research, Development and Innovation Office (NKFIH) of Hungary (K134939 to T.R.), and by the New National Excellence Program of the Ministry of Human Capacities of Hungary (ÚNKP-21-3-II-SE-45 to A.A.S.).

Left ventricular SGLT1 expression is upregulated in heart failure in humans and rat model

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Research, Development and Innovation Fund of Hungary;

Ministry of Human Capacities of Hungary

Introduction

Myocardial sodium-glucose cotransporter 1 (SGLT1) has been shown to contribute to cardiac pathological processes, whereas humans with functionally limited SGLT1 are at lower risk of developing heart failure (HF). The novel HF medications, SGLT2 inhibitors, non-selectively inhibit SGLT1 to different extent, therefore, characterization of its expression in disease conditions is relevant.

Purpose

To investigate left ventricular (LV) SGLT1 expression in humans with end-stage HF, and in a rat model of HF.

Methods

Myocardial LV samples were harvested from control subjects (Controls, n=9) undergoing valve surgery, and from patients with end-stage dilated cardiomyopathy (DCM, n=12) undergoing heart transplantation. The rat model of aorto-caval fistula (ACF, n=12) was used to induce HF with predominant LV dilation in rats during a course of 24 weeks; sham-operated animals served as controls (Sham-A, n=12). Echocardiography was used to assess LV structure and function prior to surgery in humans, as well as in rats at the end of the follow-up period. Western blotting was performed to characterize LV SGLT1 protein expression and to investigate the activity of the master regulators AMPK and ERK1/2. The extent of LV nitro-oxidative stress was quantified by immunohistochemistry (3-nitrotyrosine) in rats with HF.

Results

Both humans with DCM and rats with ACF-induced HF presented with severely dilated LVs compared to respective controls, whereas LV SGLT1 protein expression was significantly upregulated similarly by ~1.7-fold in both cases (both P<0.01). These increases in SGLT1 expressions were accompanied by significant reductions in ERK1/2 activating phosphorylation (both P<0.05), whereas AMPK activity was unaffected. In rats with HF, LV SGLT1 expression correlated significantly with the extent of myocardial nitro-oxidative stress (r=0.762, P=0.037).

Conclusions

LV SGLT1 expression is upregulated in HF in both humans and small animals, and ERK1/2 shows a concomitantly reduced activity. LV SGLT1 expression correlates with the extent of nitro-oxidative stress, suggesting a possible pathological role in HF. Whether SGLT2 inhibitors exert direct cardiac actions via inhibition of myocardial SGLT1 needs to be elucidated.

The development of systolic heart failure in case of pressure overload-induced left ventricular myocardial hypertrophy is associated with a unique microRNA expression profile in a rat model

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): New National Excellence Program of the Ministry of Human Capacities

Introduction

Growing body of evidence suggests that distinct alterations in myocardial microRNA (miRNA) expression contribute to pressure overload (PO)-induced pathological cardiac remodeling. Nevertheless, it is still under intense investigation whether the changes in miRNA expression patterns are also associated with the decompensation of LV systolic function in case of PO-evoked LV hypertrophy (LVH). Hence, we aimed to characterize miRNA expression in PO-induced LVH with and without systolic heart failure (HF).

Methods

PO was evoked by abdominal aortic banding (AB) in male Sprague-Dawley rats. Age-matched, sham-operated animals served as controls. Functional and morphological alterations were assessed by echocardiography and histology. At the end of the experimental period, rats in the AB group were subcategorized based on ejection fraction [EF] into ABLVH (EF>40%) and ABHF groups (EF<40%). Global miRNA expression profiling was performed using next generation sequencing. Bioinformatics analysis was carried out to predict miRNA-target interactions. Expression of selected target genes was measured by qRT-PCR.

Results

Increased heart weight-to-tibial length, LV mass and fibrosis confirmed the development of pathological LVH in both the ABLVH and ABHF groups. Nevertheless, increased lung weight-to-tibial length, chamber dilatation and severely reduced EF was noted only in the ABHF and not in the ABLVH, when compared to the sham group. 50 miRNA showed different expression in the ABHF compared to the ABLVH group. Based on the altered gene expression profile, in silico bioinformatics analysis predicted several target genes. Among them, reduced mRNA expression level of Fmr1 (FMRP translational regulator 1), Zfpm2 (zinc finger protein, multitype 2), Wasl (WASP like actin nucleation promoting factor), Ets1 (ETS proto-oncogene 1) and Atg16l1 (Autophagy Related 16 Like 1) was confirmed in ABHF compared to ABLVH.

Conclusions

Decompensation of systolic function in PO-induced LVH is associated with unique miRNA profile leading to specific regulation of gene expression.

Airway obstruction can be better predicted using Global Lung Function Initiative spirometry reference equations in Marfan syndrome

Marfan syndrome is a genetic disorder of the connective tissue, including involvement of the lungs.Pulmonary function test was performed in 32 asymptomatic adult Marfan patients using European Community for Coal and Steel (ECCS) and Global Lung Function Initiative (GLI) reference values.Using GLI equations for reference, significantly lower lung function values were noted for forced vital capacity (FVC) (87.0 ± 16.6% vs. 97.1 ± 16.9%; P < 0.01) and forced expiratory volume in the first second (FEV1) (79.6 ± 18.9% vs. 88.0 ± 19.1%; P < 0.01) predicted compared to ECCS. Obstructive ventilatory pattern was present in 25% of the cases when calculating with GLI lower limit of normal (LLN), and it was significantly more common in men as compared to women (n = 6, 50% vs. n = 2, 10%; P = 0.03).GLI is more suitable to detect early ventilatory changes including airway obstruction in young patients with special anatomic features, and should be used as a standard way of evaluation in asymptomatic Marfan population.

Atrial fibrillation is not associated with altered left atrial microRNA expression profile in ischemic end-stage human heart failure

Introduction

In patients with chronic heart failure (CHF) left ventricular dysfunction results in elevated left atrial (LA) pressure, triggering pathological atrial remodelling and atrial fibrillation (AF). Nevertheless, it has been reported that some patients with CHF remain in sinus rhythm (SR) despite of the pathological structural alterations (e.g. dilation and fibrosis) of the LA. Of particular interest, data is scarce regarding the molecular explanation for the observed variability in AF development among CHF patients. Recent studies have indicated that alterations in microRNA (miRNA) expression might contribute to the pathogenesis of AF. However, the majority of previous studies focusing on miRNA expression compared healthy LA with SR to pathologically remodelled, dilated LA with AF. Consequently, whether dysregulation of miRNA expression directly contribute to AF and not only to pathological LA remodelling has not been tested before.

Purpose

The present study aimed to investigate miRNA expression in comparably remodelled LA from end-stage CHF patients with permanent AF (CHF-AF) or SR (CHF-SR).

Methods

LA samples were collected from male, non-diabetic, ischemic end-stage CHF patients undergoing heart transplantation (n=24). Patients were carefully selected to avoid any differences in age (55±2 vs. 54±2 years, CHF-AF vs. CHF-SR, n.s.), ejection fraction ([EF]: 22.5±1.8 vs. 23.3±2.5%, CHF-AF vs. CHF-SR, n.s.) LA diameters (longitudinal LA diameter: 56±4 vs. 48±5mm.; CHF-AF vs. CHF-SR, n.s.; horizontal LA diameter: 61±2 vs. 54±3, CHF-AF vs. CHF-SR, n.s.) and NYHA stage. As a molecular marker of atrial load, the mRNA expression of atrial natriuretic peptide (ANP) was measured with qRT-PCR. The extent of left atrial fibrosis was assessed on picrosirius red stained histological sections. Global LA miRNA expression profiling (including the measurement of 800 human miRNA) was carried out using a commercially available kit.

Results

LA mRNA expression of ANP was comparable between the AF-CHF and the SR-CHF groups, suggesting that atrial load occurred to the same level in the two experimental groups. Furthermore, no differences could be observed in the extent of atrial collagen content between the AF-CHF and the SR-CHF groups (collagen area: 20.3±1.3% vs. 23.9±3.1%, n.s.), providing evidence that fibrotic remodelling had occurred to a similar magnitude. The high-throughput miRNA measurement revealed no differences in atrial miRNA expression between the two study groups.

Conclusion

The present study provides evidence for the first time that AF is not associated with different LA miRNA expression in end-stage CHF patients with comparable level of LA dilatation, ANP expression (atrial load) and interstitial fibrosis. Based on these findings, the potential of miRNA-based therapeutic interventions might be limited in AF patients with ischemic end-stage CHF.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): NVKP_16-1-2016-0017

Characterization of myocardial sodium-glucose cotransporter 1 expression in humans with heart failure and reduced ejection fraction

Introduction

In diabetic patients, multiple cardiovascular outcome trials consistently showed the robust cardioprotective effects of the novel antidiabetic agents, sodium glucose cotransporter 2 (SGLT2) inhibitors. However, the DAPA-HF study using the SGLT2 inhibitor dapagliflozin have extended these observations onto non-diabetic patients with heart failure (HF), urging previous hypotheses regarding the cardioprotective effects of SGLT2 inhibitors to be revised. This is further complicated by the fact that SGLT2 is not expressed in the human myocardium neither under normal nor diseased states. Hence, it has been postulated that SGLT2 inhibitors might exert direct cardioprotection via non-specific inhibition of SGLT1, which is in turn highly expressed in the myocardium.

Purpose

Because literature data is scarce regarding the expression profile of myocardial SGLT1, we aimed to characterize left ventricular SGLT1 expression in humans with end-stage HF accordingly to HF aetiology and to investigate whether cardiac resynchronization therapy (CRT) affects SGLT1 expression.

Methods

From patients undergoing mitral valve replacement with otherwise no myocardial disease and preserved LV function, we collected control papillary muscles (Control, n=9). From patients with end-stage HF undergoing heart transplantation (n=72), we obtained LV anterior wall samples according to the following HF aetiology groups: hypertrophic cardiomyopathy (HCM, n=7); idiopathic dilated cardiomyopathy (DCM, n=12); ischaemic heart disease (IHD, n=14), IHD with type 2 diabetes mellitus (IHD+T2DM, n=11); and patients with CRT (CRT-DCM, n=9; CRT-IHD, n=9; CRT-IHD+T2DM, n=10). We measured LV SGLT1 expression on the gene and protein expression levels using qRT-PCR and western blotting, respectively. Echocardiography-derived LV end-diastolic diameter (LVEDD) and LV ejection fraction (LVEF) were registered prior to surgery.

Results

Compared to controls, LV SGLT1 mRNA and protein expressions were significantly upregulated in patients with DCM, IHD and IHD+T2DM (all P&lt;0.05), but not in HCM. In these patient groups, LV SGLT1 mRNA expression showed a significant positive correlation with LVEDD (r=0.493; P&lt;0.001) and significant negative correlation with LVEF (r=−0.477; P&lt;0.001). On the protein expression level, CRT was associated with significant reduction in LV SGLT1 only in patients with DCM and IHD, but not in IHD+T2DM.

Conclusions

Myocardial SGLT1 is upregulated in patients with HF (except HCM), and correlated strongly with parameters (LVEDD, LVEF) related to adverse LV remodelling. CRT was associated with reduced SGLT1 expression in DCM and IHD patients, but not in those with IHD+T2DM. Our results suggest that SGLT1 is upregulated in HF and might be implicated in adverse myocardial remodelling. Accordingly, whether SGLT2 inhibitors exert direct cardioprotection in HFrEF via non-specific inhibition of SGLT1 needs to be further elucidated.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Research, Development and Innovation Fund of Hungary, Higher Education Institutional Excellence Programme of the Ministry of Human Capacities of Hungary

Effect of cardiac resynchronization therapy on left ventricular fibrosis-related mRNA expression profile in patients with end-stage heart failure

Background

When indicated, cardiac resynchronization therapy (biventricular pacing, CRT) decreases mortality in patients with heart failure (HF) and reduced ejection fraction, especially in those with non-ischemic cardiomyopathy. This is reflected by relatively rapid improvement of left ventricular (LV) end-diastolic diameter (LVEDD) and LV ejection fraction (LVEF) indicating reverse remodelling. These LV structural and functional improvements are accompanied by characteristic changes in LV gene expression profile. However, whether beneficial gene expression alterations related to biventricular pacing are sustained independently of structural and functional reverse remodelling is unclear.

Purpose

We aimed to compare LV fibrosis-related mRNA expression profile in end-stage HF patients with idiopathic dilated cardiomyopathy (DCM) who were not on CRT versus to those on CRT.

Methods

Left ventricular myocardial samples were harvested from end-stage HF patients undergoing heart transplantation (HTX). Inclusion criteria were negative family history of DCM, negative coronarography (i.e. non-ischemic), no relevant comorbidity (e.g. diabetes, hypertension) and no history of myocarditis. Accordingly, the following patient groups were included: 1.) DCM (n=12, 17% female, mean age [±standard deviation] 46.8±11.8 years) without CRT and 2.) CRT-DCM (n=12, 42% female, mean age 47.8±12.3 years) which comprised DCM patients on active CRT for mean 3.2±2.4 years until HTX. LV RNA was extracted and subjected to a commercially available mRNA expression panel interrogating 760 genes related to the development and regulation of fibrosis. Normalization to 10 housekeeping genes and batch corrections were conducted as per protocol. LV mRNA expression of atrial-natriuretic peptide (ANP) was quantified using qRT-PCR.

Results

Markers of reverse remodelling including LVEDD (73.4±8.3 mm vs 75.4±9.9 mm), LVEF (21.9±3.7% vs 18.5±6.8%) and LV ANP mRNA expression (arbitrary units: 1.05±1.80 vs 1.04±0.88) were comparable between DCM and CRT-DCM patients (all P&gt;0.05), respectively. High-throughput mRNA expression screening revealed significant (all P&lt;0.001) downregulation of 3 genes proven to be implicated in adverse LV remodelling: alpha catalytic subunit of protein phosphatase 2 (PPP2CA), interleukin 20 receptor subunit beta (IL20RB) and lipoprotein lipase (LPL). According to pathway analysis using directed significance scores, CRT was associated with collective upregulation of genes modifying complement activation (SERPING1, C1S, CFH) and collective downregulation of genes promoting cell proliferation (PPP2CA, ANAPC7, HSP90AA1, CSNK2B).

Conclusions

Independently of structural and functional reverse remodelling, CRT might be associated with slightly favourable LV expression profile of genes related to the regulation and development of fibrosis. This suggests that biventricular pacing might be beneficial on the molecular level beyond improvement of LV structure and function.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Research, Development and Innovation Fund of Hungary, Higher Education Institutional Excellence Programme of the Ministry of Human Capacities of Hungary

Isolation and chromosomal assignment of canine genomic BAC clones representing 25 cancer-related genes

An extensive number of genes have been implicated in the initiation and progression of human cancers, aiding our understanding of the genetic aetiology of this highly heterogeneous disease. In order to facilitate extrapolation of such information between species, we have isolated and physically mapped the canine orthologues of 25 well-characterised human cancer-related genes. The identity of PCR products representing each canine gene marker was first confirmed by DNA sequencing analysis. Each product was then radiolabelled and used to screen a genomic BAC library for the domestic dog. The chromosomal location of each positive clone in the canine karyotype was determined by fluorescence in situ hybridisation (FISH) onto canine metaphase preparations. Of the 25 genes, the FISH localisation of 21 correlated fully with that expected on the basis of known regions of conserved synteny between the human and canine genomes. Three correlated less closely, and the chromosomal location of the remaining marker showed no apparent correlation with current comparative mapping data. In addition to generating useful comparative mapping information, this panel of markers will act as a valuable resource for detailed study of candidate genes likely to be involved in tumourigenesis, and also forms the basis of a canine cancer-gene genomic microarray currently being developed for the study of unbalanced genomic aberrations in canine tumours.