Natural Compound Library Screening Identifies New Molecules for the Treatment of Cardiac Fibrosis and Diastolic Dysfunction.

BACKGROUND: Myocardial fibrosis is a hallmark of cardiac remodeling and functionally involved in heart failure development, a leading cause of deaths worldwide. Clinically, no therapeutic strategy is available that specifically attenuates maladaptive responses of cardiac fibroblasts, the effector cells of fibrosis in the heart. Therefore, our aim was to develop novel antifibrotic therapeutics based on naturally derived substance library screens for the treatment of cardiac fibrosis. METHODS: Antifibrotic drug candidates were identified by functional screening of 480 chemically diverse natural compounds in primary human cardiac fibroblasts, subsequent validation, and mechanistic in vitro and in vivo studies. Hits were analyzed for dose-dependent inhibition of proliferation of human cardiac fibroblasts, modulation of apoptosis, and extracellular matrix expression. In vitro findings were confirmed in vivo with an angiotensin II-mediated murine model of cardiac fibrosis in both preventive and therapeutic settings, as well as in the Dahl salt-sensitive rat model. To investigate the mechanism underlying the antifibrotic potential of the lead compounds, treatment-dependent changes in the noncoding RNAome in primary human cardiac fibroblasts were analyzed by RNA deep sequencing. RESULTS: High-throughput natural compound library screening identified 15 substances with antiproliferative effects in human cardiac fibroblasts. Using multiple in vitro fibrosis assays and stringent selection algorithms, we identified the steroid bufalin (from Chinese toad venom) and the alkaloid lycorine (from Amaryllidaceae species) to be effective antifibrotic molecules both in vitro and in vivo, leading to improvement in diastolic function in 2 hypertension-dependent rodent models of cardiac fibrosis. Administration at effective doses did not change plasma damage markers or the morphology of kidney and liver, providing the first toxicological safety data. Using next-generation sequencing, we identified the conserved microRNA 671-5p and downstream the antifibrotic selenoprotein P1 as common effectors of the antifibrotic compounds. CONCLUSIONS: We identified the molecules bufalin and lycorine as drug candidates for therapeutic applications in cardiac fibrosis and diastolic dysfunction.

p-SMAD2/3 and DICER promote pre-miR-21 processing during pressure overload-associated myocardial remodeling.

Transforming growth factor-ß (TGF-ß) induces miR-21 expression which contributes to fibrotic events in the left ventricle (LV) under pressure overload. SMAD effectors of TGF-ß signaling interact with DROSHA to promote primary miR-21 processing into precursor miR-21 (pre-miR-21). We hypothesize that p-SMAD-2 and -3 also interact with DICER1 to regulate the processing of pre-miR-21 to mature miR-21 in cardiac fibroblasts under experimental and clinical pressure overload. The subjects of the study were mice undergoing transverse aortic constriction (TAC) and patients with aortic stenosis (AS). In vitro, NIH-3T3 fibroblasts transfected with pre-miR-21 responded to TGF-ß1 stimulation by overexpressing miR-21. Overexpression and silencing of SMAD2/3 resulted in higher and lower production of mature miR-21, respectively. DICER1 co-precipitated along with SMAD2/3 and both proteins were up-regulated in the LV from TAC-mice. Pre-miR-21 was isolated bound to the DICER1 maturation complex. Immunofluorescence analysis revealed co-localization of p-SMAD2/3 and DICER1 in NIH-3T3 and mouse cardiac fibroblasts. DICER1-p-SMAD2/3 protein-protein interaction was confirmed by in situ proximity ligation assay. Myocardial up-regulation of DICER1 constituted a response to pressure overload in TAC-mice. DICER mRNA levels correlated directly with those of TGF-ß1, SMAD2 and SMAD3. In the LV from AS patients, DICER mRNA was up-regulated and its transcript levels correlated directly with TGF-ß1, SMAD2, and SMAD3. Our results support that p-SMAD2/3 interacts with DICER1 to promote pre-miR-21 processing to mature miR-21. This new TGFß-dependent regulatory mechanism is involved in miR-21 overexpression in cultured fibroblasts, and in the pressure overloaded LV of mice and human patients.

Potential role of microRNA-10b down-regulation in cardiomyocyte apoptosis in aortic stenosis patients.

MicroRNAs have been associated with cardiomyocyte apoptosis, a process involved in myocardial remodelling in aortic valve (Av) stenosis (AS). Our aim was to analyse whether the dysregulation of myocardial microRNAs was related to cardiomyocyte apoptosis in AS patients. Endomyocardial biopsies were obtained from 28 patients with severe AS (based on pressure gradients and Av area) referred for Av replacement and from necropsies of 10 cardiovascular disease-free control subjects. AS patients showed an increased (P<0.001) cardiomyocyte apoptotic index (CMAI) compared with controls. Two clusters of patients were identified according to the CMAI: group 1 (CMAI ≤ 0.08%; n=16) and group 2 (CMAI > 0.08%; n=12). Group 2 patients presented lower cardiomyocyte density (P<0.001) and ejection fraction (P<0.05), and higher troponin T levels (P<0.05), prevalence of heart failure (HF; P<0.05) and NT-proBNP levels (P<0.05) than those from group 1. miRNA expression profile analysed in 5 patients randomly selected from each group showed 64 microRNAs down-regulated and 6 up-regulated (P<0.05) in group 2 compared with group 1. Those microRNAs with the highest fold-change were validated in the full two groups corroborating that miR-10b, miR-125b-2* and miR-338-3p were down-regulated (P<0.05) in group 2 compared with group 1 and control subjects. These three microRNAs were inversely correlated (P<0.05) with the CMAI. Inhibition of miR-10b induced an increase (P<0.05) of apoptosis and increased expression (P<0.05) of apoptosis protease-activating factor-1 (Apaf-1) in HL-1 cardiomyocytes. In conclusion, myocardial down-regulation of miR-10b may be involved in increased cardiomyocyte apoptosis in AS patients, probably through Apaf-1 up-regulation, contributing to cardiomyocyte damage and to the development of HF.

microRNA-122 down-regulation may play a role in severe myocardial fibrosis in human aortic stenosis through TGF-ß1 up-regulation.

miRNAs (microRNAs) have been shown to play a role in myocardial fibrosis. The present study was designed to analyse whether alterations in miRNA expression contribute to the progression of myocardial fibrosis in AS (aortic valve stenosis) patients through up-regulation of the pro-fibrotic factor TGF-ß1 (transforming growth factor-ß type 1). Endomyocardial biopsies were obtained from 28 patients with severe AS, and from the necropsies of 10 control subjects. AS patients presented increased myocardial CVF (collagen volume fraction) and TGF-ß1 compared with the controls, these parameters being correlated in all patients. Patients were divided into two groups by cluster analysis according to their CVF: SF (severe fibrosis; CVF >15%; n=15) and non-SF (CVF ≤15%; n=13). TGF-ß1 was increased in patients with SF compared with those with non-SF. To analyse the involvement of miRNAs in SF, the miRNA expression profile of 10 patients (four with non-SF and six with SF) was analysed showing that 99 miRNAs were down-regulated and 19 up-regulated in the SF patients compared with the non-SF patients. Those miRNAs potentially targeting TGF-ß1 were validated by real-time RT (reverse transcription)-PCR in the whole test population, corroborating that miR-122 and miR-18b were down-regulated in patients with SF compared with those with non-SF and the control subjects. Additionally, miR-122 was inversely correlated with the CVF, TGF-ß1 and the TGF-ß1-regulated PCPE-1 (procollagen C-terminal proteinase enhancer-1) in all patients. Experiments in human fibroblasts demonstrated that miR-122 targets and inhibits TGF-ß1. In conclusion, for the first time we show that myocardial down-regulation of miR-122 might be involved in myocardial fibrosis in AS patients, probably through TGF-ß1 up-regulation.

Diffuse myocardial fibrosis: mechanisms, diagnosis and therapeutic approaches.

Diffuse myocardial fibrosis resulting from the excessive deposition of collagen fibres through the entire myocardium is encountered in a number of chronic cardiac diseases. This lesion results from alterations in the regulation of fibrillary collagen turnover by fibroblasts, facilitating the excessive deposition of type I and type III collagen fibres within the myocardial interstitium and around intramyocardial vessels. The available evidence suggests that, beyond the extent of fibrous deposits, collagen composition and the physicochemical properties of the fibres are also relevant in the detrimental effects of diffuse myocardial fibrosis on cardiac function and clinical outcomes in patients with heart failure. In this regard, findings from the past 20 years suggest that various clinicopathological phenotypes of diffuse myocardial fibrosis exist in patients with heart failure. In this Review, we summarize the current knowledge on the mechanisms and detrimental consequences of diffuse myocardial fibrosis in heart failure. Furthermore, we discuss the validity and usefulness of available imaging techniques and circulating biomarkers to assess the clinicopathological variation in this lesion and to track its clinical evolution. Finally, we highlight the currently available and potential future therapeutic strategies aimed at personalizing the prevention and reversal of diffuse myocardial fibrosis in patients with heart failure.

Cardiorenal interaction and heart failure outcomes. A role for insulin-like growth factor binding protein 2?

INTRODUCTION AND OBJECTIVES: Preliminary results suggest that high circulating insulin-like growth factor binding protein 2 (IGFBP2) levels are associated with mortality risk in heart failure (HF) patients. As IGFBP2 levels are increased in patients with chronic kidney disease (CKD), which is associated with a higher mortality risk in HF patients, we examined whether IGFBP2 is associated with CKD in HF patients, and whether CKD modifies the prognostic value of this protein in HF patients. METHODS: HF patients (n=686, mean age 66.6 years, 32.7% women) were enrolled and followed up for a median of 3.5 (min-max range: 0.1-6) years. Patients were classified as having CKD with decreased estimated glomerular filtration rate (eGFR <60mL/min/1.73 m2) or as having CKD with nondecreased eGFR (≥ 60mL/min/1.73 m2). Serum IGFBP2 was detected by ELISA. RESULTS: IGFBP2 was increased (P <.001) in CKD patients with decreased eGFR (n=290, 42.3%) compared with patients with nondecreased eGFR. IGFBP2 was directly associated with NT-proBNP (P <.001) and inversely associated with eGFR (P <.001), with both associations being independent of confounding factors. IGFBP2 was directly and independently associated with cardiovascular and all-cause death (P <.001) in the whole group of patients, but showed a stronger association with cardiovascular death in CKD patients with decreased eGFR (P for interaction <.05), improving risk prediction in these patients over clinically relevant risk factors. CONCLUSIONS: Serum IGFBP2 is associated with impaired renal function and prognosticates cardiovascular death in patients with HF and CKD with decreased eGFR. Thus, there is an effect modification of CKD on circulating IGFBP2 and on its association with cardiovascular mortality in HF patients.

Author Correction: MicroRNA-19b is a potential biomarker of increased myocardial collagen cross-linking in patients with aortic stenosis and heart failure.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Overexpression of human truncated peroxisome proliferator-activated receptor alpha induces apoptosis in HL-1 cardiomyocytes.

AIMS: Our goal was to analyse whether truncated peroxisome proliferator-activated receptor alpha (PPARalpha) overexpression induces apoptosis of cardiomyocytes. METHODS AND RESULTS: We constructed a recombinant vector of human truncated PPARalpha and a mammalian expression vector to transfect PPARalpha into a line of murine cardiomyocytes designated HL-1. Four hallmarks of apoptosis were measured in these transfected cells: depolarization of mitochondrial membrane, activation of caspase-3, phosphatidylserine (PS) externalization, and DNA fragmentation. Co-transfection with human cyclic adenosine monophosphate response element-binding protein (CREB) and human CREB binding protein (CBP) and analysis of apoptosis regulatory proteins, Bcl-2 and Bax, were also performed in truncated PPARalpha-transfected cells to determine the potential mechanisms by which truncated PPARalpha may influence apoptosis. Progressive depolarization of mitochondrial membrane, activation of caspase-3, PS externalization, DNA fragmentation, and cell death were observed in HL-1 cells upon increasing levels of transfected truncated PPARalpha. The expression of the antiapoptotic protein Bcl-2 decreased in transfected HL-1 cardiomyocytes, whereas no changes in the proapoptotic protein Bax were observed in these cells. Overexpression of CREB plus CBP abolished the inhibitory effect of truncated PPARalpha on Bcl-2 protein. CONCLUSION: These results demonstrate that human truncated PPARalpha overexpression induces apoptosis in HL-1 cardiomyocytes. In addition, our findings suggest that truncated PPARalpha may induce cardiomyocyte apoptosis through the inhibition of the antiapoptotic protein, Bcl-2. It is proposed that competition with CREB for coactivators like CBP could be involved in this inhibitory effect.

Association of depressed cardiac gp130-mediated antiapoptotic pathways with stimulated cardiomyocyte apoptosis in hypertensive patients with heart failure.

OBJECTIVE: To investigate whether the glycoprotein (gp130)-mediated survival pathway, which protects cardiomyocytes from apoptosis, is depressed in left ventricular hypertrophy hypertensive patients with chronic heart failure. METHODS: Transvenous endomyocardial biopsies were obtained in 52 hypertensive patients with left ventricular hypertrophy: 28 without heart failure and 24 with heart failure. gp130 and gp130-dependent antiapoptotic pathways p42/44 mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3 kinase (PI3K)/protein kinase B (Akt) as well as gp130 agonist cardiotrophin-1 were analyzed by reverse transcriptase-polymerase chain reaction and western blot. Apoptosis was assessed by DNA end-labeling (TUNEL), caspase-3 immunostaining and caspase substrate poly(ADP-ribose) polymerase cleavage. RESULTS: gp130 protein expression (P < 0.05) and p42/44 MAPK and PI3K/Akt activation (P < 0.01) were decreased in heart-failure hypertensive patients compared with nonheart-failure hypertensive individuals. No changes in gp130 mRNA expression were found between the two groups. Cardiotrophin-1 was increased (P < 0.05) at both the mRNA and protein levels in heart-failure hypertensive individuals compared with nonheart-failure hypertensive individuals. Cardiomyocyte apoptosis was increased (P < 0.01) in heart-failure hypertensive individuals compared with nonheart-failure hypertensive individuals. Inverse correlations (P < 0.01) occurred between cardiomyocyte apoptosis and p42/44 MAPK and PI3K/Akt activation in all hypertensive patients. Cardiotrophin-1 correlated inversely (r = -0.554, P < 0.05) with gp130 in all hypertensive individuals. In cultured HL-1 cardiomyocytes, cardiotrophin-1 decreased (P < 0.05) the gp130:phosphorylated gp130 (at Ser782) ratio and increased (P < 0.05) gp130ubiquitination. CONCLUSIONS: An association exists between depression of the gp130 cytoprotective pathway and stimulation of cardiomyocyte apoptosis in hypertensive patients that develop heart failure. Whether the excess of cardiotrophin-1 induces ligand-induced receptor down-regulation in these patients requires further study.

Altered cardiac expression of peroxisome proliferator-activated receptor-isoforms in patients with hypertensive heart disease.

OBJECTIVE: To investigate whether cardiac expression of the nuclear peroxisome proliferator-activated receptor alpha (PPARalpha) is altered in patients with hypertensive heart disease (HHD). METHODS: We studied endomyocardial septal biopsies from 24 patients with essential hypertension divided into three groups: 6 without left ventricular hypertrophy (LVH) (HT group), 10 with LVH (LVH group), and 8 with LVH and heart failure (HF) (HF group). The expression of two PPARalpha isoforms (the native active and the truncated inhibitory) was analyzed by Western blot and reverse transcription polymerase chain reaction (RT-PCR), and two PPARalpha target genes were evaluated by RT-PCR. Histomorphological features were evaluated in a second myocardial sample from LVH and HF groups. RESULTS: Whereas the expression of native PPARalpha protein was lower (p<0.05) in LVH and HF groups than in the HT group, truncated PPARalpha protein was overexpressed (p<0.001) in the HF group as compared with LVH and HT groups. The mRNA expression of native and truncated PPARalpha was similar in the three groups of hypertensives. In addition, a progressive decrease (p for trend<0.05) in the two PPARalpha target genes mRNA expression was observed among HT, LVH and HF groups. The amount of truncated PPARalpha protein correlates directly with cardiomyocytes apoptosis and inversely with cardiomyocytes density in patients with HHD. In addition, the expression of truncated PPARalpha protein was directly correlated with left ventricular volumes, and inversely with ejection fraction in all hypertensives. CONCLUSIONS: These findings suggest that post-transcriptional regulation of PPARalpha isoforms is altered in patients with HHD, namely in those developing HF. An excess of the truncated inhibitory isoform may be involved in hypertensive left ventricular failure and remodeling.

Mechanisms underlying the cardiac antifibrotic effects of losartan metabolites.

Excessive myocardial collagen deposition and cross-linking (CCL), a process regulated by lysyl oxidase (LOX), determines left ventricular (LV) stiffness and dysfunction. The angiotensin II antagonist losartan, metabolized to the EXP3179 and EXP3174 metabolites, reduces myocardial fibrosis and LV stiffness in hypertensive patients. Our aim was to investigate the differential influence of losartan metabolites on myocardial LOX and CCL in an experimental model of hypertension with myocardial fibrosis, and whether EXP3179 and EXP3174 modify LOX expression and activity in fibroblasts. In rats treated with NG-nitro-L-arginine methyl ester (L-NAME), administration of EXP3179 fully prevented LOX, CCL and connective tissue growth factor (CTGF) increase, as well as fibrosis, without normalization of blood pressure (BP). In contrast, administration of EXP3174 normalized BP and attenuated fibrosis but did not modify LOX, CCL and CTGF. In TGF-ß1-stimulated fibroblasts, EXP3179 inhibited CTGF and LOX expression and activity with lower IC50 values than EXP3174. Our results indicate that, despite a lower antihypertensive effect, EXP3179 shows higher anti-fibrotic efficacy than EXP3174, likely through its ability to prevent the excess of LOX and CCL. It is suggested that the anti-fibrotic effect of EXP3179 may be partially mediated by the blockade of CTGF-induced LOX in fibroblasts.

MicroRNA-19b is a potential biomarker of increased myocardial collagen cross-linking in patients with aortic stenosis and heart failure.

This study analyzed the potential associations of 7 myocardial fibrosis-related microRNAs with the quality of the collagen network (e.g., the degree of collagen fibril cross-linking or CCL) and the enzyme lysyl oxidase (LOX) responsible for CCL in 28 patients with severe aortic stenosis (AS) of whom 46% had a diagnosis of chronic heart failure (HF). MicroRNA expression was analyzed in myocardial and blood samples. From the studied microRNAs only miR-19b presented a direct correlation (p < 0.05) between serum and myocardium. Compared to controls both myocardial and serum miR-19b were reduced (p < 0.01) in AS patients. In addition, miR-19b was reduced in the myocardium (p < 0.01) and serum (p < 0.05) of patients with HF compared to patients without HF. Myocardial and serum miR-19b were inversely correlated (p < 0.05) with LOX, CCL and LV stiffness in AS patients. In in vitro studies miR-19b inhibition increased (p < 0.05) connective tissue growth factor protein and LOX protein expression in human fibroblasts. In conclusion, decreased miR-19b may be involved in myocardial LOX up-regulation and excessive CCL, and consequently increased LV stiffness in AS patients, namely in those with HF. Serum miR-19b can be a biomarker of these alterations of the myocardial collagen network in AS patients, particularly in patients with HF.

The Hypertensive Myocardium: From Microscopic Lesions to Clinical Complications and Outcomes.

The chronic hemodynamic load imposed by hypertension on the left ventricle leads to lesions in the myocardium that result in structural remodeling, which provides support for alterations in cardiac function, perfusion, and electrical activity that adversely influence the clinical evolution of hypertensive heart disease. Management must include detecting, reducing, and reversing left ventricular hypertrophy, as well as the detection and repair of microscopic lesions responsible for myocardial remodeling. Reducing the burden associated with hypertensive heart disease can be targeted using personalized treatment. The noninvasive, biomarker-mediated identification of subsets of patients with hypertensive heart disease is essential to provide personalized treatment.

Myocardial Collagen Cross-Linking Is Associated With Heart Failure Hospitalization in Patients With Hypertensive Heart Failure.

BACKGROUND: Excessive myocardial collagen cross-linking (CCL) determines myocardial collagen's resistance to degradation by matrix metalloproteinase (MMP)-1 and interstitial accumulation of collagen fibers with impairment of cardiac function. OBJECTIVES: This study sought to investigate whether CCL and a newly identified biomarker of this alteration are associated with hospitalization for heart failure (HHF) or cardiovascular death in patients with HF and arterial hypertension in whom other comorbidities were excluded. METHODS: Endomyocardial biopsies and blood samples from 38 patients (invasive study), and blood samples from 203 patients (noninvasive study) were analyzed. Mean follow-ups were 7.74 ± 0.58 years and 4.72 ± 0.11 years, respectively. Myocardial CCL was calculated as the ratio between insoluble and soluble collagen. The ratio between the C-terminal telopeptide of collagen type I (CITP) and matrix metalloproteinase-1 (CITP:MMP-1) was determined in blood samples. RESULTS: Invasive study: CCL was increased (p < 0.001) in patients compared with controls. Patients were categorized according to normal or high CCL values. Patients with high CCL exhibited higher risk for subsequent HHF (log-rank test p = 0.022), but not for cardiovascular death. CITP:MMP-1 was inversely associated with CCL (r = -0.460; p = 0.005) in all patients. Receiver operating characteristic curves rendered a CITP:MMP-1 cutoff ≤1.968 (80% sensitivity and 76% specificity) for predicting high CCL. Noninvasive study: Patients were categorized according to CITP:MMP-1 ratio values as normal ratio (>1.968) or low ratio (≤1.968). Patients with a low ratio exhibited higher risk for HHF (log-rank test p = 0.014), which remained significant after adjustment for relevant covariables (adjusted hazard ratio: 2.22; 95% CI: 1.37 to 3.59, p = 0.001). In addition, CITP:MMP-1-based categorization yielded significant integrated discrimination and net reclassification improvements (p = 0.003 and p = 0.009, respectively) for HHF over relevant risk factors. CITP:MMP-1 was not associated with the risk of cardiovascular death. CONCLUSIONS: Excessive myocardial CCL is associated with HHF in hypertensive patients with HF. In this population, the serum CITP:MMP-1 ratio identifies patients with increased CCL and high risk of HHF.

Association of low GLP-1 with oxidative stress is related to cardiac disease and outcome in patients with type 2 diabetes mellitus: a pilot study.

Oxidative stress (OS) contributes to cardiovascular damage in type 2 diabetes mellitus (T2DM). The peptide glucagon-like peptide-1 (GLP-1) inhibits OS and exerts cardiovascular protective actions. Our aim was to investigate whether cardiac remodeling (CR) and cardiovascular events (CVE) are associated with circulating GLP-1 and biomarkers of OS in T2DM patients. We also studied GLP-1 antioxidant effects in a model of cardiomyocyte lipotoxicity. We examined 72 T2DM patients with no coronary or valve heart disease and 14 nondiabetic subjects. A median of 6 years follow-up information was obtained in 60 patients. Circulating GLP-1, dipeptidyl peptidase-4 activity, and biomarkers of OS were quantified. In T2DM patients, circulating GLP-1 decreased and OS biomarkers increased, compared with nondiabetics. Plasma GLP-1 was inversely correlated with serum 3-nitrotyrosine in T2DM patients. Patients showing high circulating 3-nitrotyrosine and low GLP-1 levels exhibited CR and higher risk for CVE, compared to the remaining patients. In palmitate-stimulated HL-1 cardiomyocytes, GLP-1 reduced cytosolic and mitochondrial oxidative stress, increased mitochondrial ATP synthase expression, partially restored mitochondrial membrane permeability and cytochrome c oxidase activity, blunted leakage of creatine to the extracellular medium, and inhibited oxidative damage in total and mitochondrial DNA. These results suggest that T2DM patients with reduced circulating GLP-1 and exacerbated OS may exhibit CR and be at higher risk for CVE. In addition, GLP-1 exerts antioxidant effects in HL-1 palmitate-overloaded cardiomyocytes. It is proposed that therapies aimed to increase GLP-1 may counteract OS, protect from CR, and prevent CVE in patients with T2DM.

Circulating Biomarkers of Myocardial Fibrosis: The Need for a Reappraisal.

Myocardial fibrosis impairs cardiac function, in addition to facilitating arrhythmias and ischemia, and thus influences the evolution and outcome of cardiac diseases. Its assessment is therefore clinically relevant. Although tissue biopsy is the gold standard for the diagnosis of myocardial fibrosis, a number of circulating biomarkers have been proposed for the noninvasive assessment of this lesion. A review of the published clinical data available on these biomarkers shows that most of them lack proof that they actually reflect the myocardial accumulation of fibrous tissue. In this "call to action" article, we propose that this absence of proof may lead to misinterpretations when considering the incremental value provided by the biomarkers with respect to traditional diagnostic tools in the clinical handling of patients. We thus argue that strategies are needed to more strictly validate whether a given circulating biomarker actually reflects histologically proven myocardial fibrosis before it is applied clinically.

Peroxisome proliferator-activated receptor alpha and hypertensive heart disease.

Peroxisome proliferator-activated receptor alpha (PPARalpha) is a ligand-activated transcription factor belonging to the nuclear hormone receptor superfamily. It is expressed by cardiomyocytes and regulates gene expression of key proteins involved in myocardial lipid and energy metabolism. Accordingly, the activitity of PPARalpha is an important determinant of cardiomyocyte lipid homeostasis and ATP production. Currently, animal and human data suggest that deactivation of PPARalpha may contribute substantially to phenotypic changes that accompany cardiac growth in conditions of pressure overload, and the hypothesis emerges that a compromised PPARalpha activity may participate in the transition from compensated left ventricular hypertrophy to heart failure in hypertensive heart disease. The availability of PPARalpha activators (e.g. fibric acid derivates and statins) must stimulate investigation into the potential cardioprotective actions of these compounds beyond their hypolipidaemic effects and via restoration of PPARalpha activity in the hypertrophied and failing heart.

Association of cardiotrophin-1 with left ventricular systolic properties in asymptomatic hypertensive patients.

OBJECTIVES: Cardiotrophin-1 (CT-1) induces hypertrophic growth and contractile dysfunction in cardiomyocytes. This cross-sectional study was aimed to analyze CT-1 associations with echocardiographically assessed left ventricular systolic properties taking into account the influence of left ventricular growth [i.e. left ventricular hypertrophy (LVH) and inappropriate left ventricular mass (iLVM)] in asymptomatic hypertensive patients. METHODS: Serum CT-1 was measured by ELISA in 278 asymptomatic hypertensive patients with a left ventricular ejection fraction more than 50% and in 25 age and sex-matched normotensive patients. RESULTS: Serum CT-1 was increased in hypertensive patients as compared to normotensive patients. CT-1 was directly correlated with parameters of left ventricular mass (LVM) and inversely correlated with parameters assessing myocardial systolic function and left ventricular chamber contractility in hypertensive patients, these associations being independent of a number of potential confounding factors. Interestingly, the associations of CT-1 with myocardial systolic function were independent of LVM even in patients with LVH or iLVM. In addition, there was a significant increment of serum CT-1 in hypertensive patients with LVH or iLVM, especially in those in whom LVH or iLVM were accompanied by impaired myocardial systolic function, as compared to the remaining hypertensive patients and normotensive patients. Plasma amino-terminal pro-brain natriuretic peptide was not correlated with any of the assessed left ventricular systolic parameters in either group of patients. CONCLUSION: These findings suggest that serum CT-1 is associated with myocardial systolic dysfunction in asymptomatic hypertensive patients, independently of LVM, even in those patients with pathologic left ventricular growth.