TIMP-1: a marker of left ventricular diastolic dysfunction and fibrosis in hypertension

Transcriptional Activity of Metalloproteinase 9 (MMP-9) and Tissue Metalloproteinase 1 (TIMP-1) Genes as a Diagnostic and Prognostic Marker of Heart Failure Due to Ischemic Heart Disease

The most common cause of heart failure (HF) is coronary artery disease (CAD). The aim of this study was to evaluate the transcriptional activity of the metalloproteinase 9 (MMP-9) and tissue metalloproteinase inhibitor 1 (TIMP-1) genes in a study group of patients with HF due to CAD and in the control group, as well as assess the transcriptional activity of the examined genes, taking into account the number of affected coronary arteries and the severity of heart failure. The study group consisted of a total of 150 (100%) patients. The material for the study was peripheral blood, and molecular tests were performed using the quantitative QRT-PCR technique. The transcriptional activity of the MMP-9 gene was significantly higher in the group of patients with CAD and HF. It was also significantly higher with the progression of heart failure. TIMP-1 gene transcriptional activity was significantly lower with the advancement of heart failure. The transcriptional activity of the MMP-9 and TIMP-1 genes differentiated the examined patients. The severity of HF, and a significant increase in the QRT-PCR transcriptional activity of the MMP-9 gene with a simultaneous decrease in the activity of the TIMP-1 gene, makes them useful diagnostic and prognostic markers in clinical practice.

Challenges of aortic valve tissue culture - maintenance of viability and extracellular matrix in the pulsatile dynamic microphysiological system

BACKGROUND

Calcific aortic valve disease (CAVD) causes an increasing health burden in the 21st century due to aging population. The complex pathophysiology remains to be understood to develop novel prevention and treatment strategies. Microphysiological systems (MPSs), also known as organ-on-chip or lab-on-a-chip systems, proved promising in bridging in vitro and in vivo approaches by applying integer AV tissue and modelling biomechanical microenvironment. This study introduces a novel MPS comprising different micropumps in conjunction with a tissue-incubation-chamber (TIC) for long-term porcine and human AV incubation (pAV, hAV).

RESULTS

Tissue cultures in two different MPS setups were compared and validated by a bimodal viability analysis and extracellular matrix transformation assessment. The MPS-TIC conjunction proved applicable for incubation periods of 14-26 days. An increased metabolic rate was detected for pulsatile dynamic MPS culture compared to static condition indicated by increased LDH intensity. ECM changes such as an increase of collagen fibre content in line with tissue contraction and mass reduction, also observed in early CAVD, were detected in MPS-TIC culture, as well as an increase of collagen fibre content. Glycosaminoglycans remained stable, no significant alterations of α-SMA or CD31 epitopes and no accumulation of calciumhydroxyapatite were observed after 14 days of incubation.

CONCLUSIONS

The presented ex vivo MPS allows long-term AV tissue incubation and will be adopted for future investigation of CAVD pathophysiology, also implementing human tissues. The bimodal viability assessment and ECM analyses approve reliability of ex vivo CAVD investigation and comparability of parallel tissue segments with different treatment strategies regarding the AV (patho)physiology.

Progerinin, an Inhibitor of Progerin, Alleviates Cardiac Abnormalities in a Model Mouse of Hutchinson-Gilford Progeria Syndrome

Hutchinson-Gilford Progeria Syndrome (HGPS) is an ultra-rare human premature aging disorder that precipitates death because of cardiac disease. Almost all cases of HGPS are caused by aberrant splicing of the LMNA gene that results in the production of a mutant Lamin A protein termed progerin. In our previous study, treatment with Progerinin has been shown to reduce progerin expression and improve aging phenotypes in vitro and in vivo HGPS models. In this record, cardiac parameters (stroke volume (SV), ejection fraction (EF), fractional shortening (FS), etc.) were acquired in Lmna^WT/WT and Lmna^G609G/WT mice fed with either a vehicle diet or a Progerinin diet by echocardiography (from 38 weeks to 50 weeks at various ages), and then the cardiac function was analyzed. We also acquired the tissue samples and blood serum of Lmna^WT/WT and Lmna^G609G/WT mice for pathological analysis at the end of echocardiography. From these data, we suggest that the administration of Progerinin in the HGPS model mouse can restore cardiac function and correct arterial abnormalities. These observations provide encouraging evidence for the efficacy of Progerinin for cardiac dysfunction in HGPS.

Changes in Serum Levels of Matrix Metalloproteinase-1 and Tissue Inhibitor of Metalloproteinases-1 in Patients with Essential Hypertension

Hypertension (HTN) is a leading risk factor for cardiovascular (CV) disease. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) are thought to be actively involved in the remodeling of the CV extracellular matrix (ECM) during hypertensive damage. Therefore, in this study, we aimed to investigate serum levels of MMP-1 and TIMP-1 in patients with essential HTN and compare them with those of normotensive individuals. We measured serum concentrations of MMP-1 and TIMP-1 in 60 patients with HTN and 20 healthy controls using an ELISA. The obtained results showed that in patients with HTN, the mean levels of MMP-1 (1.82 ± 0.9 ng/mL) were significantly higher (p = 0.03) than the mean levels in the control group (1.19 ± 0.7 ng/mL). The levels of TIMP-1 in patients with essential HTN (0.44 ± 0.1 ng/mL) were also significantly higher (p = 0.005) than those in the control group (0.33 ± 0.1 ng/mL). In HTN, elevated serum MMP-1 levels may be associated with increased collagen degradation in the CV ECM, whereas elevated TIMP-1 levels may favor its accumulation and the development of pathological remodeling and fibrosis of the heart and arterial vessels.

A Porcine Model of Heart Failure With Preserved Ejection Fraction Induced by Chronic Pressure Overload Characterized by Cardiac Fibrosis and Remodeling

Heart failure is induced by multiple pathological mechanisms, and current therapies are ineffective against heart failure with preserved ejection fraction (HFpEF). As there are limited animal models of HFpEF, its underlying mechanisms have not yet been elucidated. Here, we employed the descending aortic constriction (DAC) technique to induce chronic pressure overload in the left ventricles of Tibetan minipigs for 12 weeks. Cardiac function, pathological and cellular changes, fibrotic signaling activation, and gene expression profiles were explored. The left ventricles developed concentric hypertrophy from weeks 4 to 6 and transition to dilation starting in week 10. Notably, the left ventricular ejection fraction was maintained at >50% in the DAC group during the 12-week period. Pathological examination, biochemical analyses, and gene profile analysis revealed evidence of inflammation, fibrosis, cell death, and myofilament dephosphorylation in the myocardium of HFpEF model animals, together with gene expression shifts promoting cardiac remodeling and downregulating metabolic pathways. Furthermore, we noted the activation of several signaling proteins that impact cardiac fibrosis and remodeling, including transforming growth factor-β/SMAD family members 2/3, type I/III/V collagens, phosphatidylinositol 3-kinase, extracellular signal-regulated kinase, matrix metalloproteinases 2 and 9, tissue inhibitor of metalloproteinases 1 and 2, interleukins 6 and 1β, and inhibitor of κBα/nuclear factor-κB. Our findings demonstrate that this chronic pressure overload-induced porcine HFpEF model is a powerful tool to elucidate the mechanisms of this disease and translate preclinical findings.

Inflammageing in the cardiovascular system: mechanisms, emerging targets, and novel therapeutic strategies

In the elderly population, pathological inflammation has been associated with ageing-associated diseases. The term 'inflammageing', which was used for the first time by Franceschi and co-workers in 2000, is associated with the chronic, low-grade, subclinical inflammatory processes coupled to biological ageing. The source of these inflammatory processes is debated. The senescence-associated secretory phenotype (SASP) has been proposed as the main origin of inflammageing. The SASP is characterised by the release of inflammatory cytokines, elevated activation of the NLRP3 inflammasome, altered regulation of acetylcholine (ACh) nicotinic receptors, and abnormal NAD+ metabolism. Therefore, SASP may be 'druggable' by small molecule therapeutics targeting those emerging molecular targets. It has been shown that inflammageing is a hallmark of various cardiovascular diseases, including atherosclerosis, hypertension, and adverse cardiac remodelling. Therefore, the pathomechanism involving SASP activation via the NLRP3 inflammasome; modulation of NLRP3 via α7 nicotinic ACh receptors; and modulation by senolytics targeting other proteins have gained a lot of interest within cardiovascular research and drug development communities. In this review, which offers a unique view from both clinical and preclinical target-based drug discovery perspectives, we have focused on cardiovascular inflammageing and its molecular mechanisms. We have outlined the mechanistic links between inflammageing, SASP, interleukin (IL)-1β, NLRP3 inflammasome, nicotinic ACh receptors, and molecular targets of senolytic drugs in the context of cardiovascular diseases. We have addressed the 'druggability' of NLRP3 and nicotinic α7 receptors by small molecules, as these proteins represent novel and exciting targets for therapeutic interventions targeting inflammageing in the cardiovascular system and beyond.

Galectin-3 Inhibition With Modified Citrus Pectin in Hypertension

We investigated the effect of galectin-3 (Gal-3) inhibition with modified citrus pectin on markers of collagen metabolism in a proof-of-concept randomized placebo-controlled trial of participants with elevated Gal-3 levels and hypertension. Although higher Gal-3 levels were associated with female sex, diabetes, and reduced glomerular filtration rate in cross-sectional analyses, treatment with modified citrus pectin did not change collagen markers. The effect of Gal-3 inhibition among individuals with heart failure warrants further investigation.

Roles of Biomarkers in Myocardial Fibrosis

Myocardial fibrosis is observed in various cardiovascular diseases and plays a key role in the impairment of cardiac function. Endomyocardial biopsy, as the gold standard for the diagnosis of myocardial fibrosis, has limitations in terms of clinical application. Therefore, biomarkers have been recommended for noninvasive assessment of myocardial fibrosis. This review discusses the role of biomarkers in myocardial fibrosis from the perspective of collagen.

Matrix Metalloproteinases and Tissue Inhibitors of Metalloproteinases in Extracellular Matrix Remodeling during Left Ventricular Diastolic Dysfunction and Heart Failure with Preserved Ejection Fraction: A Systematic Review and Meta-Analysis

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are pivotal regulators of extracellular matrix (ECM) composition and could, due to their dynamic activity, function as prognostic tools for fibrosis and cardiac function in left ventricular diastolic dysfunction (LVDD) and heart failure with preserved ejection fraction (HFpEF). We conducted a systematic review on experimental animal models of LVDD and HFpEF published in MEDLINE or Embase. Twenty-three studies were included with a total of 36 comparisons that reported established LVDD, quantification of cardiac fibrosis and cardiac MMP or TIMP expression or activity. LVDD/HFpEF models were divided based on underlying pathology: hemodynamic overload (17 comparisons), metabolic alteration (16 comparisons) or ageing (3 comparisons). Meta-analysis showed that echocardiographic parameters were not consistently altered in LVDD/HFpEF with invasive hemodynamic measurements better representing LVDD. Increased myocardial fibrotic area indicated comparable characteristics between hemodynamic and metabolic models. Regarding MMPs and TIMPs; MMP2 and MMP9 activity and protein and TIMP1 protein levels were mainly enhanced in hemodynamic models. In most cases only mRNA was assessed and there were no correlations between cardiac tissue and plasma levels. Female gender, a known risk factor for LVDD and HFpEF, was underrepresented. Novel studies should detail relevant model characteristics and focus on MMP and TIMP protein expression and activity to identify predictive circulating markers in cardiac ECM remodeling.

Matrix Metalloproteinases Increase Because of Hypoperfusion in Obstructive Hypertrophic Cardiomyopathy

BACKGROUND

Myocardial fibrosis (MF) is considered a result of microvascular dysfunction in patients with hypertrophic cardiomyopathy. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), capable of degrading collagen, directly participate in the development of MF. First we investigated the relationships among MF, microvascular rarefaction, and MMPs. Then we assessed the prognostic value of MF-related circulating biomarkers.

METHODS

Fifty-five obstructive hypertrophic cardiomyopathy (HOCM) patients were enrolled after surgical myectomy. Myocardial samples were performed with Masson's trichrome staining and immunohistochemical procedures for collagen volume fraction and microvascular density, respectively. Enzyme-linked immunosorbent assays were used to assess myocardial and plasma of MMP-2, MMP-9, and TIMP-1 and plasma C-terminal propeptide of procollagen type Ⅰ (PICP) and C-terminal telopeptide of type Ⅰ collagen (ICTP) levels. The composite cardiovascular endpoint consisted of new-onset atrial fibrillation, heart failure requiring hospitalization, and all-cause death.

RESULTS

In HOCM patients microvascular density was associated with the myocardial MMP-2/TIMP-1 ratio (r = -0.348, P = .009), whereas no correlation was found between collagen volume fraction and myocardial MMPs. During the 44-month follow-up 6 patients experienced a cardiovascular endpoint. The plasma PICP/ICTP ratio and MMP-2/TIMP-1 ratio were the 2 strongest prognostic makers. In multivariable analyses high PICP/ICTP and MMP-2/TIMP-1 ratios remained independent predictors of cardiovascular outcomes after adjusting for clinical confounders (hazard ratios, 12.683 [P = .021] and 17.037 [P = .027], respectively).

CONCLUSIONS

In HOCM patients the myocardial MMP-2/TIMP-1 ratio was elevated because of microvascular rarefaction but may not be responsible for MF. High plasma PICP/ICTP and MMP-2/TIMP-1 ratios are independent predictors of adverse outcomes in HOCM patients.

Atrial fibrillation and cardiac fibrosis: A review on the potential of extracellular matrix proteins as biomarkers

The involvement of fibrosis as an underlying pathology in heart diseases is becoming increasingly clear. In recent years, fibrosis has been granted a causative role in heart diseases and is now emerging as a major contributor to Atrial Fibrillation (AF) pathogenesis. AF is the most common arrhythmia encountered in the clinic, but the substrate for AF is still being debated. Consensus in the field is a combination of cardiac tissue remodeling, inflammation and genetic predisposition. The extracellular matrix (ECM) is subject of growing investigation, since measuring circulatory biomarkers of ECM formation and degradation provides both diagnostic and prognostic information. However, fibrosis is not just fibrosis. Each specific collagen biomarker holds information on regulatory mechanisms, as well as information about which section of the ECM is being remodeled, providing a detailed description of cardiac tissue homeostasis. This review entails an overview of the implication of fibrosis in AF, the different collagens and their significance, and the potential of using biomarkers of ECM remodeling as tools for understanding AF pathogenesis and identifying patients at risk for further disease progression.

Tissue Inhibitor of Matrix Metalloproteinase 1 Increases With Ageing and Can Be Associated With Stroke ― Nested Case-Control Study ―

Background: Increase of collagen in the extracellular matrix occurs with ageing. We investigated whether a collagen marker, tissue inhibitor of matrix metalloproteinase 1 (TIMP-1), was associated with risk of stroke.

Methods and Results: In a nested case-control study of 953 subjects from the general population, we evaluated determinants of TIMP-1 level and stroke risk. Mean subject age was 65.7±8.6 years (53.0% men); TIMP-1 was 72.4±28.2 pg/mL in the control group and 75.3±30.9 pg/mL in the stroke group. The relationship between TIMP-1 quartile and stroke was J-curved. Subjects in the highest TIMP-1 quartile (≥89 ng/mL) had a significantly higher OR of stroke (59–72 ng/mL; OR, 1.90; 95% CI: 1.09–3.31, P=0.023) than those in the second TIMP-1 quartile, and this tended toward significance even after adjusting for confounding factors (P=0.059). Elevation of serum TIMP-1 became more marked after age 65 years. On multiple linear regression analysis, significant determinants of TIMP-1 were older age (B=0.21 per 1 year; 95% CI: 0.52–1.07, P<0.001) and higher systolic blood pressure (SBP; B=0.19 per 1 mmHg, 95% CI: 0.08–0.42, P=0.004).

Conclusions: TIMP-1 increased with ageing and with SBP, and can be associated with stroke.

Plasma matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs and aging and lifelong exercise adaptations in ventricular and arterial stiffness

The age-associated increase in cardiac and central arterial stiffness is attenuated with lifelong (>25 years) endurance exercise in a dose-dependent manner. Remodelling of the extracellular matrix of cardiovascular structures may underpin these lifelong exercise adaptations in structural stiffness. The primary aim was to examine whether matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) levels are associated with aging and lifelong exercise-related changes in cardiac and central arterial stiffness. Plasma MMPs and TIMPs, left ventricular (LV) (LV stiffness constant) and central arterial stiffness (pulse wave velocity) were examined in healthy adults stratified into five groups based on age and lifelong weekly exercise frequency: (1) young sedentary adults (28-50 years), and older adults (>60 years) who had performed either: (a) sedentary (0-1 sessions/week), (b) casual (2-3 sessions/week), (c) committed (4-5 sessions/week) or (d) athletic (≥6 sessions/week) frequency of exercise. MMP-1 was significantly lower in young compared to older sedentary (p = 0.049). Except for TIMP-2 (p = 0.018 versus committed) and the ratio of MMP-2/TIMP-4 (p = 0.047 versus committed), MMP and TIMP expression was not significantly different in lifelong exercise groups (≥casual) compared to the older sedentary group. MMP-1, -3 had a weak positive relationship with central PWV (r = 0.17-0.25, p ≤ 0.050) but there were no significant relationships between MMPs or TIMPs and LV stiffness constant (p ≥ 0.148). In conclusion, there was not a clear or consistent difference in plasma MMPs and TIMPs with lifelong exercise dose despite exhibiting lower cardiovascular stiffness at the highest exercise levels.

Bioinformatic analysis reveals novel hub genes and pathways associated with hypertensive nephropathy

AIM

Hypertensive nephropathy (HTN) is one of the leading causes of end-stage renal disease and is closely associated with inflammation and tubule-interstitial fibrosis. The molecular mechanism underlying HTN remains unclear. This study used bioinformatic analysis to identify the novel gene targets for HTN.

METHODS

We downloaded the microarray data of GSE99325 and GSE32591 from Gene Expression Omnibus. The dataset comprised 20 HTN and 15 normal samples. The differentially expressed genes (DEG) were identified, and then gene ontology (GO) enrichment was performed, and a GO tree was constructed by using clusterProfiler and ClueGO. In addition, a protein-protein interaction network was established using the Search Tool for the Retrieval of Interacting Genes database and visualized by Cytoscape. The novel hub genes were validated in in vitro experiments.

RESULTS

A total of 267 genes (117 up-regulated and 150 down-regulated genes) were identified as DEG. GO analysis and the GO tree indicated that the DEG were mainly associated with steroid hormone response and the extracellular matrix. Based on the protein-protein interaction network, we screened out several novel hub genes. Considering the findings and the literature review, we focused on and validated the dual specificity phosphatase 1, tissue inhibitor of matrix metalloproteinases 1, fos proto-oncogene and jun proto-oncogenes, which may play significant roles in the pathogenesis of HTN. These findings were consistent with the bioinformatic results for the in vitro validation.

CONCLUSION

This study identified for the first time novel hub genes with microarray data in HTN by using bioinformatic analysis and provided novel evidence and clues for future works.

Recent Advances in Imaging of Hypertensive Heart Disease

PURPOSE OF REVIEW

To review recent advances in the imaging of hypertensive heart disease (HHD) with an emphasis on developments in the imaging of diffuse myocardial fibrosis using cardiac magnetic resonance (CMR).

RECENT FINDINGS

HHD results from long-standing hypertension and is characterized by the development of left ventricular hypertrophy and diffuse interstitial fibrosis. Diffuse fibrosis traditionally required endomyocardial biopsy to diagnose, but recent developments using T1 mapping in CMR allow for noninvasive assessment. Studies using T1 mapping have shown an increase in extracellular volume fraction (ECV) in patients with HHD compared to normal controls, suggesting ECV can be used as a noninvasive marker for fibrosis in HHD. In addition to T1 mapping, other recent advances in HHD imaging include improvements in three-dimensional echocardiography, allowing for accurate real-time volumetric measurements, and the use of speckle tracking echocardiography to detect subclinical systolic dysfunction. Measurement of ECV using T1 mapping in CMR can be used as a noninvasive marker of diffuse myocardial fibrosis in HHD. While further studies are needed to validate this approach with larger patient cohorts, ECV can potentially be used to both monitor disease progression and assess therapeutic interventions in HHD.

Shensong Yangxin capsule reduces atrial fibrillation susceptibility by inhibiting atrial fibrosis in rats with post-myocardial infarction heart failure

Purpose

Shensong Yangxin (SSYX) capsule is a traditional Chinese medicine that has been used widely to treat cardiac arrhythmia. This study aimed to assess whether SSYX prevents atrial fibrillation (AF) after chronic myocardial infarction (MI)-induced heart failure and to determine the underlying mechanisms.

Materials and methods

The study included 45 male Sprague Dawley rats. The rats underwent MI induction or sham surgery. One week after MI induction surgery, we performed serial echocardiography and administered SSYX capsule to some rats that experienced MI. After 4 weeks of treatment, AF inducibility was assessed with transesophageal programmed electrical stimulation technology. Additionally, multielectrode array assessment, histological analysis, and Western blot analysis were performed.

Results

AF inducibility was significantly lower in SSYX rats than in MI rats (33.3% vs 73.3%, P<0.05). Additionally, conduction velocities in the left atrium were greater in SSYX rats than in MI rats. Moreover, SSYX decreased left atrial fibrosis, downregulated TGF-β1, MMP-9, TIMP-I, and type I and III collagen expressions, and inhibited the differentiation of cardiac fibroblasts to myofibroblasts.

Conclusion

SSYX reduces AF inducibility after MI by improving left atrial conduction function via the inhibition of left atrial fibrosis. It prevents the development of an MI-induced vulnerable substrate for AF.

Association of isolated minor nonspecific ST-T abnormalities with left ventricular hypertrophy and diastolic dysfunction

The aim of this study was to examine the associations of isolated minor nonspecific ST-T abnormalities (NSSTTA) on 12-lead electrocardiogram (ECG) with left ventricular (LV) diastolic function and LV geometry on echocardiography. A cross-sectional study comprised of 74,976 Koreans who underwent ECG and echocardiography as part of a comprehensive health examination between March 2011 and December 2014. ECG was coded using Minnesota Code criteria. The frequencies of NSSTTA, impaired LV relaxation, and echocardiographic LVH were 1,139 (1.5%), 21,118 (28.2%), and 1,687 (2.3%) patients, respectively. The presence of NSSTTA was positively associated with the prevalence of impaired LV relaxation and LVH on echocardiography. In a multivariable-adjusted model, the odds ratio (95% CIs) comparing patients with NSSTTA to control patients was 1.55 (1.33-1.80) for impaired LV relaxation and 3.15 (2.51-3.96) for echocardiographic LVH. The association between NSSTTA and impaired LV relaxation was stronger in the intermediate to high cardiovascular disease-risk group than in the low-risk group according to Framingham Risk Score stratification (P for interaction = 0.02). NSSTTA were associated with increased prevalence of impaired LV relaxation and LVH, suggesting NSSTTA as an early indicator of subclinical cardiac dysfunction and geometric abnormalities.

Inhibitor of lysyl oxidase improves cardiac function and the collagen/MMP profile in response to volume overload

The cardiac extracellular matrix is a complex architectural network that serves many functions, including providing structural and biochemical support to surrounding cells and regulating intercellular signaling pathways. Cardiac function is directly affected by extracellular matrix (ECM) composition, and alterations of the ECM contribute to the progression of heart failure. Initially, collagen deposition is an adaptive response that aims to preserve tissue integrity and maintain normal ventricular function. However, the synergistic effects of proinflammatory and profibrotic responses induce a vicious cycle, which causes excess activation of myofibroblasts, significantly increasing collagen deposition and accumulation in the matrix. Furthermore, excess synthesis and activation of the enzyme lysyl oxidase (LOX) during disease increases collagen cross-linking, which significantly increases collagen resistance to degradation by matrix metalloproteinases (MMPs). In the present study, the aortocaval fistula model of volume overload (VO) was used to determine whether LOX inhibition could prevent adverse changes in the ECM and subsequent cardiac dysfunction. The major findings from this study were that LOX inhibition 1) prevented VO-induced increases in left ventricular wall stress; 2) partially attenuated VO-induced ventricular hypertrophy; 3) completely blocked the increases in fibrotic proteins, including collagens, MMPs, and their tissue inhibitors; and 4) prevented the VO-induced decline in cardiac function. It remains unclear whether a direct interaction between LOX and MMPs exists; however, our experiments suggest a potential link between the two because LOX inhibition completely attenuated VO-induced increases in MMPs. Overall, our study demonstrated key cardioprotective effects of LOX inhibition against adverse cardiac remodeling due to chronic VO. NEW & NOTEWORTHY Although the primary role of lysyl oxidase (LOX) is to cross-link collagens, we found that elevated LOX during cardiac disease plays a key role in the progression of heart failure. Here, we show that inhibition of LOX in volume-overloaded rats prevented the development of cardiac dysfunction and improved ventricular collagen and matrix metalloproteinase/tissue inhibitor of metalloproteinase profiles.

Cardiac fibrosis in mouse expressing DsRed tetramers involves chronic autophagy and proteasome degradation insufficiency

Proteinopathy in the heart which often manifests excessive misfolded/aggregated proteins in cardiac myocytes can result in severe fibrosis and heart failure. Here we developed a mouse model, which transgenically express tetrameric DsRed, a red fluorescent protein (RFP), in an attempt to mimic the pathological mechanisms ofcardiac fibrosis. Whilst DsRed is expressed and forms aggregation in most mouse organs, certain pathological defects are specifically recapitulated in cardiac muscle cells including mitochondria damages, aggresome-like residual bodies, excessive ubiquitinated proteins, and the induction of autophagy. The proteinopathy and cellular injuries caused by DsRed aggregates may be due to impaired or overburdened ubiquitin-proteasome system and autophagy-lysosome systems. We further identified that DsRed can be ubiquitinated and associated with MuRF1, a muscle-specific E3 ligase. Concomitantly, an activation of NF-κB signaling and a strong TIMP1 induction were noted, suggesting that RFP-induced fibrosis was augmented by a skewed balance between TIMP1 and MMPs. Taken together, our study highlights the molecular consequences of uncontrolled protein aggregation leading to congestive heart failure, and provides novel insights into fibrosis formation that can be exploited for improved therapy.

The effect of antihypertensive treatment on arterial stiffness and serum concentration of selected matrix metalloproteinases

INTRODUCTION

The aim of the study was to assess the arterial stiffness and serum levels of selected metalloproteinases (MMPs) in hypertensive patients and their changes following antihypertensive therapy.

MATERIAL AND METHODS

The study group consisted of 95 patients with essential arterial hypertension (HT) stage 1 or 2 (mean age: 53.1 ±13.0 years). The control group consisted of 31 normotensives of the same age range. Hypertension patients were randomized to one of the following monotherapies for 6 months: quinapril, losartan, amlodipine, hydrochlorothiazide or bisoprolol. Carotid-femoral pulse wave velocity (PWV) was measured using a Complior device. Serum concentrations of MMPs (proMMP-1, MMP-2, MMP-3, MMP-9) and plasma concentration of tissue inhibitor of MMPs (TIMP-1) were measured using ELISA.

RESULTS

Pulse wave velocity and serum concentrations of MMP-2 and MMP-9 were higher in HT patients than in the control group. In HT patients PWV was significantly associated (R² = 0.41) with age (B = 0.408, p = 0.00027), systolic blood pressure (SBP) (B = 0.441, p = 0.0011), and MMP-3 (B = 0.204, p = 0.0459). After 6 months of treatment, regardless of the agent used, we observed a significant decrease of PWV, SBP, MMP-2 and MMP-3 and an increase of TIMP-1 plasma concentration. The decrease of PWV was significantly associated with a decrease of SBP (R² = 0.07, B = 0.260, p = 0.015) only.

CONCLUSIONS

In patients with arterial hypertension, beside age and systolic blood pressure, the determinants of arterial stiffness include serum MMP-3 concentration. For drugs compared in the study with the same hypotensive effect obtained, the arterial stiffness reduction effect is not dependent on the drug used. Systolic blood pressure is one of the independent factors responsible for the reduction of arterial stiffness in the course of antihypertensive treatment.

Tissue Inhibitor of Matrix Metalloproteinase-1 Promotes Myocardial Fibrosis by Mediating CD63-Integrin β1 Interaction

Myocardial fibrosis is excess accumulation of the extracellular matrix fibrillar collagens. Fibrosis is a key feature of various cardiomyopathies and compromises cardiac systolic and diastolic performance. TIMP1 (tissue inhibitor of metalloproteinase-1) is consistently upregulated in myocardial fibrosis and is used as a marker of fibrosis. However, it remains to be determined whether TIMP1 promotes tissue fibrosis by inhibiting extracellular matrix degradation by matrix metalloproteinases or via an matrix metalloproteinase-independent pathway. We examined the function of TIMP1 in myocardial fibrosis using Timp1-deficient mice and 2 in vivo models of myocardial fibrosis (angiotensin II infusion and cardiac pressure overload), in vitro analysis of adult cardiac fibroblasts, and fibrotic myocardium from patients with dilated cardiomyopathy (DCM). Timp1 deficiency significantly reduced myocardial fibrosis in both in vivo models of cardiomyopathy. We identified a novel mechanism for TIMP1 action whereby, independent from its matrix metalloproteinase-inhibitory function, it mediates an association between CD63 (cell surface receptor for TIMP1) and integrin β1 on cardiac fibroblasts, initiates activation and nuclear translocation of Smad2/3 and β-catenin, leading to de novo collagen synthesis. This mechanism was consistently observed in vivo, in cultured cardiac fibroblasts, and in human fibrotic myocardium. In addition, after long-term pressure overload, Timp1 deficiency persistently reduced myocardial fibrosis and ameliorated diastolic dysfunction. This study defines a novel matrix metalloproteinase-independent function of TIMP1 in promoting myocardial fibrosis. As such targeting TIMP1 could prove to be a valuable approach in developing antifibrosis therapies.

Wnt5a is elevated in heart failure and affects cardiac fibroblast function

Wnt signaling is dysregulated in heart failure (HF) and may promote cardiac hypertrophy, fibrosis, and inflammation. Blocking the Wnt ligand Wnt5a prevents HF in animal models. However, the role of Wnt5a in human HF and its functions in cardiac cells remain unclear. Here, we investigated Wnt5a regulation in HF patients and its effects on primary mouse and human cardiac fibroblasts. Serum Wnt5a was elevated in HF patients and associated with hemodynamic, neurohormonal, and clinical measures of disease severity. In failing human hearts, Wnt5a protein correlated with interleukin (IL)-6 and tissue inhibitor of metalloproteinase (TIMP)-1. Wnt5a messenger RNA (mRNA) levels were markedly upregulated in failing myocardium and both mRNA and protein levels declined following left ventricular assist device therapy. In primary mouse and human cardiac fibroblasts, recombinant Wnt5a dose-dependently upregulated mRNA and protein release of IL-6 and TIMP-1. Wnt5a did not affect β-catenin levels, but activated extracellular signal-regulated kinase 1/2 (ERK1/2) signaling. Importantly, inhibition of ERK1/2 activation attenuated Wnt5a-induced release of IL-6 and TIMP-1. In conclusion, our results show that Wnt5a is elevated in the serum and myocardium of HF patients and is associated with measures of progressive HF. Wnt5a induces IL-6 and TIMP-1 in cardiac fibroblasts, which might promote myocardial inflammation and fibrosis, and thereby contribute to HF progression.

KEY MESSAGES

• Wnt5a is elevated in serum and myocardium of HF patients and is associated with measures of progressive HF. • In cardiac fibroblasts, Wnt5a upregulates interleukin (IL)-6 and tissue inhibitor of metalloproteinase (TIMP)-1 through the ERK pathway. • Wnt5a-mediated effects might promote myocardial inflammation and fibrosis, and thereby contribute to HF progression.

Physical versus psychological social stress in male rats reveals distinct cardiovascular, inflammatory and behavioral consequences

Repeated exposure to social stress can precipitate the development of psychosocial disorders including depression and comorbid cardiovascular disease. While a major component of social stress often encompasses physical interactions, purely psychological stressors (i.e. witnessing a traumatic event) also fall under the scope of social stress. The current study determined whether the acute stress response and susceptibility to stress-related consequences differed based on whether the stressor consisted of physical versus purely psychological social stress. Using a modified resident-intruder paradigm, male rats were either directly exposed to repeated social defeat stress (intruder) or witnessed a male rat being defeated. Cardiovascular parameters, behavioral anhedonia, and inflammatory cytokines in plasma and the stress-sensitive locus coeruleus were compared between intruder, witness, and control rats. Surprisingly intruders and witnesses exhibited nearly identical increases in mean arterial pressure and heart rate during acute and repeated stress exposures, yet only intruders exhibited stress-induced arrhythmias. Furthermore, re-exposure to the stress environment in the absence of the resident produced robust pressor and tachycardic responses in both stress conditions indicating the robust and enduring nature of social stress. In contrast, the long-term consequences of these stressors were distinct. Intruders were characterized by enhanced inflammatory sensitivity in plasma, while witnesses were characterized by the emergence of depressive-like anhedonia, transient increases in systolic blood pressure and plasma levels of tissue inhibitor of metalloproteinase. The current study highlights that while the acute cardiovascular responses to stress were identical between intruders and witnesses, these stressors produced distinct differences in the enduring consequences to stress, suggesting that witness stress may be more likely to produce long-term cardiovascular dysfunction and comorbid behavioral anhedonia while exposure to physical stressors may bias the system towards sensitivity to inflammatory disorders.

Effects of 12 weeks of atorvastatin therapy on myocardial fibrosis and circulating fibrosis biomarkers in statin-naïve patients with hypertension with atherosclerosis

The purpose of this study was to assess the effects of 12 weeks of atorvastatin treatment on myocardial fibrosis in patients with hypertension with atherosclerosis. 15 statin-naïve participants (11 males; mean age 67±10 years) with atherosclerosis were given atorvastatin (40 mg/day) for 12 weeks and underwent echocardiography including ultrasonic tissue characterization by cyclic variation of integrated backscatter (CVIBS). Serum galectin-3 and fibrosis markers including aminoterminal propeptide of type III procollagen (PIIINP), matrix metalloproteinase-2, metalloproteinase-9, and tissue inhibitor of metalloproteinase-1 (TIMP-1) were also analyzed. After 12 weeks of atorvastatin (40 mg/day) treatment, serum total cholesterol and low-density lipoprotein cholesterol decreased significantly (204±31 to 140±24 mg/dL and 133±26 to 69±17 ng/mL, respectively, both p<0.001). In myocardial fibrosis analysis, CVIBS increased significantly (6.6±1.9 to 8.5±2.7 dB, p=0.024). In addition, the circulating fibrosis markers serum PIIINP and TIMP-1 decreased significantly (9.5±2.7 to 6.4±1.4 ng/mL, p=0.012 and 299±65 to 250±45 ng/mL, p=0.024, respectively). 12 weeks of medium dose atorvastatin treatment resulted in a significant reduction in myocardial fibrosis as evaluated by morphofunctional parameters and plasma markers of tissue fibrosis.

Trial registration number

NTC00172419; results.

Role of MMP-2 and MMP-9 in resistance to drug therapy in patients with resistant hypertension

Background

Despite the increased evidence of the important role of matrix metalloproteinases (MMP-9 and MMP‑2) in the pathophysiology of hypertension, the profile of these molecules in resistant hypertension (RHTN) remains unknown.

Objectives

To compare the plasma levels of MMP-9 and MMP-2 and of their tissue inhibitors (TIMP-1 and TIMP-2, respectively), as well as their MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios, between patients with controlled RHTN (CRHTN, n=41) and uncontrolled RHTN (UCRHTN, n=35). In addition, the association of those parameters with clinical characteristics, office blood pressure (BP) and arterial stiffness (determined by pulse wave velocity) was evaluate in those subgroups.

Methods

This study included 76 individuals diagnosed with RHTN and submitted to physical examination, electrocardiogram, and laboratory tests to assess biochemical parameters.

Results

Similar values of MMP-9, MMP-2, TIMP-1, TIMP-2, and MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios were found in the UCRHTN and CRHTN subgroups (P>0.05). A significant correlation was found between diastolic BP (DBP) and MMP-9/TIMP-1 ratio (r=0.37; P=0.02) and DPB and MMP-2 (r=-0.40; P=0.02) in the UCRHTN subgroup. On the other hand, no correlation was observed in the CRHTN subgroup. Logistic regression models demonstrated that MMP-9, MMP-2, TIMP-1, TIMP-2 and their ratios were not associated with the lack of BP control.

Conclusion

These findings suggest that neither MMP-2 nor MMP-9 affect BP control in RHTN subjects.

Effect of QiShenYiQi Pill on Myocardial Collagen Metabolism in Rats with Partial Abdominal Aortic Coarctation

This study investigated the effect of QiShenYiQi pill (QSYQ) on myocardial collagen metabolism in rats with partial abdominal aortic coarctation and explored its mechanism of action. A series of assays were used to detect the effect and mechanism of QSYQ on systolic blood pressure, heart mass index, left ventricle mass index, HYP, expression of PICP, PIIINT, and CTX-I in serum, MMP-1, and TIMP-1 expression in myocardium. We observed that QSYQ can reduce the rate of myocardial collagen synthesis and increase the rate of myocardial collagen degradation. It also effectively improved the degree of myocardial fibrosis in partial abdominal aortic rats and it had a tendency to have a greater effect with longer treatment duration, which is related to the mechanism of regulation of MMP-1 and TIMP-1 expression in the myocardial rat.

Biomarkers of cardiomyocyte injury and stress identify left atrial and left ventricular remodelling and dysfunction: A population-based study

BACKGROUND/OBJECTIVES

The validation of effective screening tools for the identification of patients with subclinical myocardial remodelling is a major clinical need. Thus, we explored the associations of circulating biomarkers of cardiomyocyte injury and stress with subclinical cardiac remodelling and dysfunction, and with biomarkers reflecting collagen turnover.

METHODS

We randomly recruited 727 subjects from a general population (51.2% women; mean age 51.3 years). Measurements included echocardiographic left atrial (LA) and left ventricular (LV) structure and function, quantification of high sensitivity cardiac Troponin T (hs-cTnT), NT-proBNP, and biomarkers of collagen types I and III turnover.

RESULTS

In unadjusted and adjusted analyses, the prevalence of LA enlargement (LAE), LV hypertrophy (LVH) and LV diastolic dysfunction (LVDD) increased with higher hs-cTnT (P ≤ 0.031). NT-proBNP was independently associated with LVDD (P=0.009). Both biomarkers combined yielded significant integrated discrimination and net reclassification improvements (P ≤ 0.014 and P ≤ 0.009, respectively) for LAE, LVH and LVDD, over the conventional risk factors, and were independently and positively associated with biomarkers of collagen type I turnover. In a sensitivity analysis, after excluding participants with previous cardiac diseases, our findings remained consistent.

CONCLUSIONS

Our population-based study suggested that subclinical LV and LA remodelling were associated with hs-cTnT, and that, in combination with NT-proBNP, hs-cTnT showed incremental diagnostic utility over the conventional risk factors. Both biomarkers were associated with biomarkers of collagen type I turnover. Thus, biomarkers of cardiomyocyte microinjury and hemodynamic stress may stimulate fibrosis-related mechanisms and facilitate the diagnosis of subclinical LA and LV remodelling and dysfunction in the general population.

Cardiomyocyte-specific expression of CYP2J2 prevents development of cardiac remodelling induced by angiotensin II

AIMS

Cardiac remodelling is one of the key pathological changes that occur with cardiovascular disease. Previous studies have demonstrated the beneficial effects of CYP2J2 expression on cardiac injury. In the present study, we investigated the effects of cardiomyocyte-specific CYP2J2 expression and EET treatment on angiotensin II-induced cardiac remodelling and sought to determine the underlying molecular mechanisms involved in this process.

METHODS AND RESULTS

Eight-week-old mice with cardiomyocyte-specific CYP2J2 expression (αMHC-CYP2J2-Tr) and wild-type (WT) control mice were treated with Ang-II. Ang-II treatment of WT mice induced changes in heart morphology, cardiac hypertrophy and dysfunction, as well as collagen accumulation; however, cardiomyocyte-specific expression of CYP2J2 attenuated these effects. The cardioprotective effects observed in α-MHC-CYP2J2-Tr mice were associated with peroxisome proliferator-activated receptor (PPAR)-γ activation, reduced oxidative stress, reduced NF-κB p65 nuclear translocation, and inhibition of TGF-β1/smad pathway. The effects seen with cardiomyocyte-specific expression of CYP2J2 were partially blocked by treatment with PPAR-γ antagonist GW9662. In in vitro studies, 11,12-EET(1 μmol/L) treatment attenuated cardiomyocyte hypertrophy and remodelling-related protein (collagen I, TGF-β1, TIMP1) expression by inhibiting the oxidative stress-mediated NF-κB pathway via PPAR-γ activation. Furthermore, conditioned media from neonatal cardiomyocytes treated with 11,12-EET inhibited activation of cardiac fibroblasts and TGF-β1/smad pathway.

CONCLUSION

Cardiomyocyte-specific expression of CYP2J2 or treatment with EETs protects against cardiac remodelling by attenuating oxidative stress-mediated NF-κBp65 nuclear translocation via PPAR-γ activation.

Beneficial effects of renal sympathetic denervation on cardiovascular inflammation and remodeling in essential hypertension

BACKGROUND

Renal sympathetic denervation (RSD) represents a potential treatment option for certain patients with resistant arterial hypertension (HT). HT is associated with chronic vascular inflammation and remodeling, contributing to progressive vascular damage, and atherosclerosis. The present study aimed to evaluate the influence of RSD on cardiovascular inflammation and remodeling by determining serum levels of interleukin-6 (IL-6), high-sensitive C-reactive protein (hsCRP), matrix metalloproteinases (MMP), and tissue inhibitor of metalloproteinases (TIMP).

METHODS

A total of 60 consecutive patients (age 67.9 ± 9.6 years) undergoing RSD were included. A therapeutic response was defined as an office systolic blood pressure (SBP) reduction of >10 mmHg 6 months after RSD. Venous serum samples for measurement of hsCRP, IL-6, MMP-2, MMP-9, and TIMP-1 were collected prior to and 6 months after RSD.

RESULTS

A significant reduction in office SBP of 26.4 mmHg [SBPbaseline 169.3 mmHg (SD 11.3), p < 0.001] was documented 6 months after RSD. The serum levels of hsCRP (p < 0.001) and the pro-inflammatory cytokine IL-6 (p < 0.001) were significantly decreased compared to baseline values. The levels of MMP-9 (p = 0.024) and MMP-2 (p < 0.01) were significantly increased compared to baseline values.

CONCLUSION

In addition to the effective blood pressure reduction in response to RSD, this study demonstrates a positive effect of RSD on biomarkers reflecting vascular inflammation and remodeling. These results suggest a possible prognostic benefit of RSD in high-risk patients for endothelial dysfunction and cardiovascular remodeling as well as end-organ damage.

Tissue inhibitor of metalloproteinases (TIMPs) in heart failure

Remodeling of the myocardium and the extracellular matrix (ECM) occurs in heart failure irrespective of its initial cause. The ECM serves as a scaffold to provide structural support as well as housing a number of cytokines and growth factors. Hence, disruption of the ECM will result in structural instability as well as activation of a number of signaling pathways that could lead to fibrosis, hypertrophy, and apoptosis. The ECM is a dynamic entity that undergoes constant turnover, and the integrity of its network structure is maintained by a balance in the function of matrix metalloproteinases (MMPs) and their inhibitors, the tissue inhibitor of metalloproteinases (TIMPs). In heart disease, levels of MMPs and TIMPs are altered resulting in an imbalance between these two families of proteins. In this review, we will discuss the structure, function, and regulation of TIMPs, their MMP-independent functions, and their role in heart failure. We will review the knowledge that we have gained from clinical studies and animal models on the contribution of TIMPs in the development and progression of heart disease. We will further discuss how ECM molecules and regulatory genes can be used as biomarkers of disease in heart failure patients.

Molecular and cellular basis for diastolic dysfunction

Heart failure with preserved ejection fraction (HFpEF) is highly prevalent and is frequently associated with metabolic risk factors. Patients with HFpEF have only a slightly lower mortality than patients with HF and reduced EF. The pathophysiology of HFpEF is currently incompletely understood, which precludes specific therapy. Both HF phenotypes demonstrate distinct cardiac remodeling processes at the macroscopic, microscopic, and ultrastructural levels. Increased diastolic left-ventricular (LV) stiffness and impaired LV relaxation are important features of HFpEF, which can be explained by changes in the extracellular matrix and the cardiomyocytes. In HFpEF, elevated intrinsic cardiomyocyte stiffness contributes to high diastolic LV stiffness. Posttranslational changes in the sarcomeric protein titin, affecting titin isoform expression and phosphorylation, contribute to elevated cardiomyocyte stiffness. Increased nitrosative/oxidative stress, impaired nitric oxide bioavailability, and down-regulation of myocardial cyclic guanosine monophosphate and protein kinase G signaling could trigger posttranslational modifications of titin, thereby augmenting cardiomyocyte and LV diastolic stiffness.

Role of various proteases in cardiac remodeling and progression of heart failure

It is believed that cardiac remodeling due to geometric and structural changes is a major mechanism for the progression of heart failure in different pathologies including hypertension, hypertrophic cardiomyopathy, dilated cardiomyopathy, diabetic cardiomyopathy, and myocardial infarction. Increases in the activities of proteolytic enzymes such as matrix metalloproteinases, calpains, cathepsins, and caspases contribute to the process of cardiac remodeling. In addition to modifying the extracellular matrix, both matrix metalloproteinases and cathepsins have been shown to affect the activities of subcellular organelles in cardiomyocytes. The activation of calpains and caspases has been identified to induce subcellular remodeling in failing hearts. Proteolytic activities associated with different proteins including caspases, calpain, and the ubiquitin-proteasome system have been shown to be involved in cardiomyocyte apoptosis, which is an integral part of cardiac remodeling. This article discusses and compares how the activities of various proteases are involved in different cardiac abnormalities with respect to alterations in apoptotic pathways, cardiac remodeling, and cardiac dysfunction. An imbalance appears to occur between the activities of some proteases and their endogenous inhibitors in various types of hypertrophied and failing hearts, and this is likely to further accentuate subcellular remodeling and cardiac dysfunction. The importance of inhibiting the activities of both extracellular and intracellular proteases specific to distinct etiologies, in attenuating cardiac remodeling and apoptosis as well as biochemical changes of subcellular organelles, in heart failure has been emphasized. It is suggested that combination therapy to inhibit different proteases may prove useful for the treatment of heart failure.

Membrane-associated matrix proteolysis and heart failure

The extracellular matrix (ECM) is a complex entity containing a large portfolio of structural proteins, signaling molecules, and proteases. Changes in the overall integrity and activational state of these ECM constituents can contribute to tissue structure and function, which is certainly true of the myocardium. Changes in the expression patterns and activational states of a family of ECM proteolytic enzymes, the matrix metalloproteinases (MMPs), have been identified in all forms of left ventricle remodeling and can be a contributory factor in the progression to heart failure. However, new clinical and basic research has identified some surprising and unpredicted changes in MMP profiles in left ventricle remodeling processes, such as with pressure or volume overload, as well as with myocardial infarction. From these studies, it has become recognized that proteolytic processing of signaling molecules by certain MMP types, particularly the transmembrane MMPs, actually may facilitate ECM accumulation and modulate fibroblast transdifferentiation; both are critical events in adverse left ventricle remodeling. Based on the ever-increasing substrates and diversity of biological actions of MMPs, it is likely that continued research about the relationship of left ventricle remodeling in this family of proteases will yield new insights into the ECM remodeling process and new therapeutic targets.

Improvement in collagen metabolism after 12 weeks' cardiac resynchronization therapy in patients with ischaemic cardiomyopathy

OBJECTIVES

To investigate the effects of cardiac resynchronization therapy (CRT) on collagen metabolism biomarkers and their relationship to cardiac function, in patients with ischaemic cardiomyopathy (ICM).

METHODS

Serum levels of matrix metalloproteinase (MMP)-9, tissue inhibitor of MMP-9 (TIMP-1), carboxyterminal propeptide of type I procollagen (PICP) and carboxyterminal telopeptide of type I collagen (ICTP) were quantified before and after 12 weeks' treatment, in patients with ICM receiving CRT and standard medical therapy (CRT group) or standard medical therapy alone (non-CRT group), and in controls. Cardiac function was measured echocardiographically.

RESULTS

MMP-9, TIMP-1, ICTP and the MMP-9/TIMP-1 ratio were significantly higher, and the PICP/ICTP ratio significantly lower, in patients with ICM (n = 27) compared with controls (n = 20). After 12 weeks' treatment, MMP-9, TIMP-1, ICTP and the MMP-9/TIMP-1 ratio were significantly higher, and the PICP/ICTP ratio significantly lower, in the non-CRT group (n = 15) compared with the CRT group (n = 12). The PICP/ICTP ratio correlated positively with TIMP-1 and negatively with MMP-9. The early/atrial ratio and left ventricular ejection fraction correlated positively and negatively, respectively, with the MMP-9/TIMP-1 ratio. Echocardiographic measurements of cardiac function were significantly worse in patients with ICM compared with controls and improved significantly after treatment in the CRT group.

CONCLUSIONS

In ICM, collagen degradation biomarkers were elevated and correlated positively with cardiac function. CRT partially reversed the deterioration in collagen metabolism and enhanced cardiac function.

Levels of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 mRNAs in patients with primary hypertension or hypertension-induced atherosclerosis

OBJECTIVE

Matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) affect degradation of vascular elastin, collagen remodelling and formation of atherosclerotic plaque. This cross-sectional study investigated the levels of MMP-9 and TIMP-1 mRNAs in the blood of patients with primary hypertension with and without hypertension-induced carotid atherosclerosis.

METHODS

Hypertensive patients with and without atherosclerosis and age- and gender-matched normotensive subjects were enrolled. MMP-9 and TIMP-1 mRNA were quantified using real-time reverse transcription-polymerase chain reaction.

RESULTS

Hypertensive patients (n = 86) had significantly lower levels of TIMP-1 mRNA than normotensive subjects (n = 43). Hypertensive patients with atherosclerosis (n = 42) showed significantly elevated levels of MMP-9 mRNA compared with both normotensive subjects and hypertensive patients without atherosclerosis (n = 44).

CONCLUSIONS

Primary hypertension resulted in decreased TIMP-1 mRNA levels, suggesting a potential mechanism contributing to the degradation of elastin. Hypertension-induced atherosclerosis was associated with significantly increased levels of MMP-9 mRNA, which may enhance both the deposition of types I and III collagen and atherosclerotic plaque formation.

Calcific aortic stenosis: a disease of the valve and the myocardium

Although aortic stenosis is a common condition associated with major morbidity, mortality, and health economic costs, there are currently no medical interventions capable of delaying or halting its progression. Re-evaluation of the underlying pathophysiology is therefore required so that novel therapeutic strategies can be developed. Aortic stenosis is characterized by progressive aortic valve narrowing and secondary left ventricular hypertrophy. Both processes are important because in combination they drive the development of symptoms and adverse events that characterize the latter stages of the disease. In this review, the authors examine the pathophysiology of aortic stenosis with respect to both the valve and the myocardium. In particular, the authors focus on the role of inflammation, fibrosis, and calcification in progressive valve narrowing and then examine the development of left ventricular hypertrophy, its subsequent decompensation, and the transition to heart failure. Finally the authors discuss potential therapeutic strategies on the basis of similarities aortic stenosis shares with other pathological conditions.

Cardiac fibroblasts, fibrosis and extracellular matrix remodeling in heart disease

Fibroblasts comprise the largest cell population in the myocardium. In heart disease, the number of fibroblasts is increased either by replication of the resident myocardial fibroblasts, migration and transformation of circulating bone marrow cells, or by transformation of endothelial/epithelial cells into fibroblasts and myofibroblasts. The primary function of fibroblasts is to produce structural proteins that comprise the extracellular matrix (ECM). This can be a constructive process; however, hyperactivity of cardiac fibroblasts can result in excess production and deposition of ECM proteins in the myocardium, known as fibrosis, with adverse effects on cardiac structure and function. In addition to being the primary source of ECM proteins, fibroblasts produce a number of cytokines, peptides, and enzymes among which matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitor of metalloproteinases (TIMPs), directly impact the ECM turnover and homeostasis. Function of fibroblasts can also in turn be regulated by MMPs and TIMPs. In this review article, we will focus on the function of cardiac fibroblasts in the context of ECM formation, homeostasis and remodeling in the heart. We will discuss the origins and multiple roles of cardiac fibroblasts in myocardial remodeling in different types of heart disease in patients and in animal models. We will further provide an overview of what we have learned from experimental animal models and genetically modified mice with altered expression of ECM regulatory proteins, MMPs and TIMPs.

Plasma levels of matrix metalloproteinases and their inhibitors in hypertension: a systematic review and meta-analysis

BACKGROUND

Hypertension is a major cause of cardiovascular remodeling. In the cardiovascular system, the remodeling of the extracellular matrix is controlled by the matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs). The aim of this meta-analysis is to elucidate the behavior of plasma MMP and TIMP levels in hypertension and their relationship to cardiovascular remodeling.

METHODS

MEDLINE and EMBASE databases were searched up to July 2011. Studies were considered eligible if they provided values of plasma MMPs and TIMPs in hypertensive patients. Given the high variability of the plasma biomarker values among studies, the standardized mean difference (SMD) was calculated.

RESULTS

Ten studies provided plasma MMP-9; the SMD between 778 hypertensive patients and 669 controls was 1.95 units (P < 0.05). Thirteen studies provided plasma TIMP-1; the SMD between 851 hypertensive patients and 646 normotensive individuals was 1.92 units (P < 0.01). Three studies investigated whether plasma TIMP-1 predicted left ventricular (LV) remodeling; the SMD between 92 hypertensive patients with and 88 hypertensive patients without LV hypertrophy was 5.81 units (P < 0.05). As for diastolic heart failure (HF), five studies provided data for plasma MMP-2; the SMD between 321 hypertensive patients with and 334 hypertensive patients without HF was 2.36 units (P < 0.01). The heterogeneity among studies was high.

CONCLUSIONS

These results suggest that MMP-2, MMP-9 and TIMP-1 may have a role as biomarkers of cardiovascular remodeling in hypertension. If these results are confirmed in prospective clinical studies, they could provide new tools to stratify cardiovascular risk in hypertensive patients.

Overexpression of TIMP-1 in embryonic stem cells attenuates adverse cardiac remodeling following myocardial infarction

Transplanted embryonic stem (ES) cells, following myocardial infarction (MI), contribute to limited cardiac repair and regeneration with improved function. Therefore, novel strategies are still needed to understand the effects of genetically modified transplanted stem cells on cardiac remodeling. The present study evaluates whether transplanted mouse ES cells overexpressing TIMP-1, an antiapoptotic and antifibrotic protein, can enhance cardiac myocyte differentiation, inhibit native cardiac myocyte apoptosis, reduce fibrosis, and improve cardiac function in the infarcted myocardium. MI was produced in C57BL/6 mice by coronary artery ligation. TIMP-1-ES cells, ES cells, or culture medium (control) were transplanted into the peri-infarct region of the heart. Immunofluorescence, TUNEL staining, caspase-3 activity, ELISAs, histology, and echocardiography were used to identify newly differentiated cardiac myocytes and assess apoptosis, fibrosis, and heart function. Two weeks post-MI, significantly (p < 0.05) enhanced engraftment and cardiac myocyte differentiation was observed in TIMP-1-ES cell-transplanted hearts compared with hearts transplanted with ES cells and control. Hearts transplanted with TIMP-1-ES cells demonstrated a reduction in apoptosis as well as an increase (p< 0.05) in p-Akt activity compared with ES cells or culture media controls. Infarct size and interstitial and vascular fibrosis were significantly (p< 0.05) decreased in the TIMP-1-ES cell group compared to controls. Furthermore, MMP-9, a key profibrotic protein, was significantly (p < 0.01) reduced following TIMP-1-ES cell transplantation. Echocardiography data showed fractional shortening and ejection fraction were significantly (p< 0.05) improved in the TIMP-1-ES cell group compared with respective controls. Our data suggest that transplanted ES cells overexpressing TIMP-1 attenuate adverse myocardial remodeling and improve cardiac function compared with ES cells that may have therapeutic potential in regenerative medicine.

Matrix metalloproteinases

Remodeling of extracellular matrix is crucial for many physiological (cell migration, proliferation, growth, and development) and pathological (remodeling of heart, carcinogenesis, metastasis, etc.) events. Thus, the interaction between cells and extracellular matrix plays a key role in normal development and differentiation of organism and many pathological states as well. Changes in extracellular matrix are regulated by a system of proteolytic enzymes that are responsible for proteolysis of huge quantity of extracellular matrix components. Matrix metalloproteinases (MMPs) represent the main group of regulating proteases in ECM. Ability of matrix metalloproteinases to modify the structural integrity of tissues is essential for certain aspects of normal physiology and pathology. The ability to process molecules such as growth factors, receptors, adhesion molecules, other proteinases, and proteinase inhibitors makes MMPs potent controllers of physiological and pathological events in the cell microenvironment. Overactivation of MMPs has been implicated in numerous disease states.

Effects of DPP-4 inhibitors on the heart in a rat model of uremic cardiomyopathy

Background

Uremic cardiomyopathy contributes substantially to mortality in chronic kidney disease (CKD) patients. Glucagon-like peptide-1 (GLP-1) may improve cardiac function, but is mainly degraded by dipeptidyl peptidase-4 (DPP-4).

Methodology/Principal Findings

In a rat model of chronic renal failure, 5/6-nephrectomized [5/6N] rats were treated orally with DPP-4 inhibitors (linagliptin, sitagliptin, alogliptin) or placebo once daily for 4 days from 8 weeks after surgery, to identify the most appropriate treatment for cardiac dysfunction associated with CKD. Linagliptin showed no significant change in blood level AUC(0-∞) in 5/6N rats, but sitagliptin and alogliptin had significantly higher AUC(0-∞) values; 41% and 28% (p = 0.0001 and p = 0.0324), respectively. No correlation of markers of renal tubular and glomerular function with AUC was observed for linagliptin, which required no dose adjustment in uremic rats. Linagliptin 7 µmol/kg caused a 2-fold increase in GLP-1 (AUC 201.0 ng/l*h) in 5/6N rats compared with sham-treated rats (AUC 108.6 ng/l*h) (p = 0.01). The mRNA levels of heart tissue fibrosis markers were all significantly increased in 5/6N vs control rats and reduced/normalized by linagliptin.

Conclusions/Significance

DPP-4 inhibition increases plasma GLP-1 levels, particularly in uremia, and reduces expression of cardiac mRNA levels of matrix proteins and B-type natriuretic peptides (BNP). Linagliptin may offer a unique approach for treating uremic cardiomyopathy in CKD patients, with no need for dose-adjustment.