Hypertensive Heart Disease: A Narrative Review Series-Part 3: Vasculature, Biomarkers and the Matrix of Hypertensive Heart Disease

Over the last few decades, research efforts have resulted in major advances in our understanding of the pathophysiology of hypertensive heart disease (HHD). This is the third part of a three-part review series. Here, we focus on the influence of high blood pressure on the micro- and macroalterations that occur in the vasculature in HHD. We also provide an overview of circulating cardiac biomarkers that may prove useful for a better understanding of the pathophysiology, development and progression of HHD, and may play a unique role in the diagnostic and prognostic evaluation of patients with HHD, taking into account their properties showing as abnormal long before the onset of the disease. In the conclusion, we propose an updated definition of HHD and a matrix for clinical classification, which we suspect will be useful in practice, allowing an individual approach to HHD patients.

Cardiac Remodeling in Hypertension: Clinical Impact on Brain, Heart, and Kidney Function

Hypertension is the most common causative factor of cardiac remodeling, which, in turn, has been associated with changes in brain and kidney function. Currently, the role of blood biomarkers as indices of cardiac remodeling remains unclear. In contrast, cardiac imaging, including echocardiography and cardiovascular magnetic resonance (CMR), has been a valuable noninvasive tool to assess cardiac remodeling. Cardiac remodeling during the course of systemic hypertension is not the sole effect of the latter. "Remodeling" of other vital organs, such as brain and kidney, also takes place. Therefore, it will be more accurate if we discuss about "hypertensive remodeling" involving the heart, the brain, and the kidneys, rather than isolated cardiac remodeling. This supports the idea of their simultaneous assessment to identify the early, silent lesions of total "hypertensive remodeling". In this context, magnetic resonance imaging is the ideal modality to provide useful information about these organs in a noninvasive fashion and without radiation. For this purpose, we propose a combined protocol to employ MRI in the simultaneous assessment of the heart, brain and kidneys. This protocol should include all necessary indices for the evaluation of "hypertensive remodeling" in these 3 organs, and could be performed within a reasonable time, not exceeding one hour, so that it remains patient-friendly. Furthermore, a combined protocol may offer "all in one examination" and save time. Finally, the amount of contrast agent used will be limited granted that post-contrast evaluations of the three organs will be performed after 1 injection.

Ensemble machine learning model identifies patients with HFpEF from matrix-related plasma biomarkers

Arterial hypertension can lead to structural changes within the heart including left ventricular hypertrophy (LVH) and eventually heart failure with preserved ejection fraction (HFpEF). The initial diagnosis of HFpEF is costly and generally based on later stage remodeling; thus, improved predictive diagnostic tools offer potential clinical benefit. Recent work has shown predictive value of multibiomarker plasma panels for the classification of patients with LVH and HFpEF. We hypothesized that machine learning algorithms could substantially improve the predictive value of circulating plasma biomarkers by leveraging more sophisticated statistical approaches. In this work, we developed an ensemble classification algorithm for the diagnosis of HFpEF within a population of 480 individuals including patients with HFpEF, patients with LVH, and referent control patients. Algorithms showed strong diagnostic performance with receiver-operating-characteristic curve (ROC) areas of 0.92 for identifying patients with LVH and 0.90 for identifying patients with HFpEF using demographic information, plasma biomarkers related to extracellular matrix remodeling, and echocardiogram data. More impressively, the ensemble algorithm produced an ROC area of 0.88 for HFpEF diagnosis using only demographic and plasma panel data. Our findings demonstrate that machine learning-based classification algorithms show promise as a noninvasive diagnostic tool for HFpEF, while also suggesting priority biomarkers for future mechanistic studies to elucidate more specific regulatory roles.NEW & NOTEWORTHY Machine learning algorithms correctly classified patients with heart failure with preserved ejection fraction with over 90% area under receiver-operating-characteristic curves. Classifications using multidomain features (demographics and circulating biomarkers and echo-based ventricle metrics) proved more accurate than previous studies using single-domain features alone. Excitingly, HFpEF diagnoses were generally accurate even without echo-based measurements, demonstrating that such algorithms could provide an early screening tool using blood-based measurements before sophisticated imaging.

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.

Procollagen C-proteinase enhancer-1 (PCPE-1), a potential biomarker and therapeutic target for fibrosis

The correct balance between collagen synthesis and degradation is essential for almost every aspect of life, from development to healthy aging, reproduction and wound healing. When this balance is compromised by external or internal stress signals, it very often leads to disease as is the case in fibrotic conditions. Fibrosis occurs in the context of defective tissue repair and is characterized by the excessive, aberrant and debilitating deposition of fibril-forming collagens. Therefore, the numerous proteins involved in the biosynthesis of fibrillar collagens represent a potential and still underexploited source of therapeutic targets to prevent fibrosis. One such target is procollagen C-proteinase enhancer-1 (PCPE-1) which has the unique ability to accelerate procollagen maturation by BMP-1/tolloid-like proteinases (BTPs) and contributes to trigger collagen fibrillogenesis, without interfering with other BTP functions or the activities of other extracellular metalloproteinases. This role is achieved through a fine-tuned mechanism of action that is close to being elucidated and offers promising perspectives for drug design. Finally, the in vivo data accumulated in recent years also confirm that PCPE-1 overexpression is a general feature and early marker of fibrosis. In this review, we describe the results which presently support the driving role of PCPE-1 in fibrosis and discuss the questions that remain to be solved to validate its use as a biomarker or therapeutic target.

Predictive Value of Sirtuins in Acute Myocardial Infarction - Bridging the Bench to the Clinical Practice

Acute myocardial infarction (AMI) is a non-transmissible condition with high prevalence, morbidity, and mortality. Different strategies for the management of AMI are employed worldwide, but its early diagnosis remains a major challenge. Many molecules have been proposed in recent years as predictive agents in the early detection of AMI, including troponin (C, T, and I), creatine kinase MB isoenzyme, myoglobin, heart-type fatty acid-binding protein, and a family of histone deacetylases with enzymatic activities named sirtuins. Sirtuins may be used as predictive or complementary treatment strategies and the results of recent preclinical studies are promising. However, human clinical trials and data are scarce, and many issues have been raised regarding the predictive values of sirtuins. The present review summarizes research on the predictive value of sirtuins in AMI. We also briefly summarize relevant clinical trials and discuss future perspectives and possible clinical applications.

Circulating biomarkers in the early detection of hypertensive heart disease: usefulness in the developing world

Although the varying phenotypic spectra of hypertensive heart disease (HHD) can be assessed by electrocardiography (ECG), echocardiography and cardiovascular magnetic resonance (CMR), ECG criteria for left ventricular hypertrophy (LVH) are insensitive, while echocardiography and CMR are expensive, less readily available and often lack requisite expertise. Consequently, the use of circulating biomarkers in the diagnosis and prognostication of HHD beyond the traditional N-terminal pro- b-type natriuretic peptide (NT-proBNP) and B-type natriuretic peptide (BNP) have become an attractive alternative. We carried out a PubMed and Google Scholar databases' search of original articles on circulating biomarkers used in the diagnosis of the different spectrum of HHD over the last 10 years [2005-2015] in humans. Fourteen studies met the inclusion criteria with NT-pro BNP being the most studied circulating biomarker in HHD followed by soluble ST2 (sST2). There is a lack of data on the use of circulating biomarkers in HHD. There is a need to explore further this area of investigative cardiology.

Analysis of mast cells and myocardial fibrosis in autopsied patients with hypertensive heart disease

OBJECTIVE

To analyze the percentage of collagen fibers and mast cell density in the left ventricular myocardium of autopsied patients with and without hypertensive heart disease.

METHODS

Thirty fragments of left ventricular myocardium were obtained from individuals autopsied at the Clinical Hospital of the Federal University of Triângulo Mineiro (UFTM) in the period from 1987 to 2017. Individuals were divided into two groups: those with hypertensive heart disease (HD) and those with no heart disease (ND). Subjects were also assessed according to age, gender and race (white and non-white). Collagen fibers were quantified by computed morphometry and mast cell density was assessed by immunohistochemical methods.

RESULTS

There were significantly more collagen fibers in the left ventricle in the HD group than in the ND group (p<0.001). Mast cell density was significantly higher in the left ventricle of individuals with HD immunolabeled with anti-chymase and anti-tryptase antibodies (p=0.02) and also of those immunolabeled only with anti-tryptase antibodies (p=0.03). Analyzing the HD group, there was a significant positive correlation between the percentage of collagen fibers in the left ventricle and mast cell density immunolabeled by anti-chymase and anti-tryptase antibodies (p=0.04) and also mast cell density immunolabeled only with anti-tryptase antibodies (p=0.02).

CONCLUSIONS

Mast cells are involved in the development of hypertensive heart disease, contributing to the remodeling of collagen fibers in this disease.

Oleic Acid Attenuates Ang II (Angiotensin II)-Induced Cardiac Remodeling by Inhibiting FGF23 (Fibroblast Growth Factor 23) Expression in Mice

Plasma metabolic profiles were compared between patients with hypertension with and without left ventricular hypertrophy and significantly decreased oleic acid (OA) levels were observed in the peripheral blood of patients with hypertension with left ventricular hypertrophy. We sought to determine the effect and underlying mechanisms of OA on cardiac remodeling. In vitro studies with isolated neonatal mouse cardiomyocytes and cardiac fibroblasts revealed that OA significantly attenuated Ang II (angiotensin II)-induced cardiomyocyte growth and cardiac fibroblast collagen expression. In vivo, cardiac function, hypertrophic growth of cardiomyocytes, and fibrosis were analyzed after an Ang II (1000 ng/kg/minute) pump was implanted for 14 days. We found that OA could significantly prevent Ang II-induced cardiac remodeling in mice. RNA sequencing served as a gene expression roadmap highlighting gene expression changes in the hearts of Ang II-induced mice and OA-treated mice. The results revealed that FGF23 (fibroblast growth factor 23) expression was significantly upregulated in mouse hearts in response to Ang II infusion, which was significantly suppressed in the hearts of OA-treated mice. Furthermore, overexpression of FGF23 in the heart by injection of an AAV-9 vector aggravated Ang II-induced cardiac remodeling and impaired the protective effect of OA on cardiac remodeling. Further study found that OA could suppress Ang II-induced FGF23 expression by inhibiting the translocation of Nurr1 (nuclear receptor–related 1 protein) from the cytoplasm to the nucleus. Our findings suggest a novel role of OA in preventing Ang II-induced cardiac remodeling via suppression of FGF23 expression.

Cell-specific ablation of Hsp47 defines the collagen-producing cells in the injured heart

Collagen production in the adult heart is thought to be regulated by the fibroblast, although cardiomyocytes and endothelial cells also express multiple collagen mRNAs. Molecular chaperones are required for procollagen biosynthesis, including heat shock protein 47 (Hsp47). To determine the cell types critically involved in cardiac injury–induced fibrosis theHsp47 gene was deleted in cardiomyocytes, endothelial cells, or myofibroblasts. Deletion ofHsp47 from cardiomyocytes during embryonic development or adult stages, or deletion from adult endothelial cells, did not affect cardiac fibrosis after pressure overload injury. However, myofibroblast-specific ablation of Hsp47; blocked fibrosis and deposition of collagens type I, III, and V following pressure overload as well as significantly reduced cardiac hypertrophy. Fibroblast-specific Hsp47-deleted mice showed lethality after myocardial infarction injury, with ineffective scar formation and ventricular wall rupture. Similarly, only myofibroblast-specific deletion of Hsp47reduced fibrosis and disease in skeletal muscle in a mouse model of muscular dystrophy. Mechanistically, deletion of Hsp47 from myofibroblasts reduced mRNA expression of fibrillar collagens and attenuated their proliferation in the heart without affecting paracrine secretory activity of these cells. The results show that myofibroblasts are the primary mediators of tissue fibrosis and scar formation in the injured adult heart, which unexpectedly affects cardiomyocyte hypertrophy.

Cardiac-specific ablation of the E3 ubiquitin ligase Mdm2 leads to oxidative stress, broad mitochondrial deficiency and early death

The maintenance of normal heart function requires proper control of protein turnover. The ubiquitin-proteasome system is a principal regulator of protein degradation. Mdm2 is the main E3 ubiquitin ligase for p53 in mitotic cells thereby regulating cellular growth, DNA repair, oxidative stress and apoptosis. However, which of these Mdm2-related activities are preserved in differentiated cardiomyocytes has yet to be determined. We sought to elucidate the role of Mdm2 in the control of normal heart function. We observed markedly reduced Mdm2 mRNA levels accompanied by highly elevated p53 protein expression in the hearts of wild type mice subjected to myocardial infarction or trans-aortic banding. Accordingly, we generated conditional cardiac-specific Mdm2 gene knockout (Mdm2^f/f;mcm) mice. In adulthood, Mdm2^f/f;mcm mice developed spontaneous cardiac hypertrophy, left ventricular dysfunction with early mortality post-tamoxifen. A decreased polyubiquitination of myocardial p53 was observed, leading to its stabilization and activation, in the absence of acute stress. In addition, transcriptomic analysis of Mdm2-deficient hearts revealed that there is an induction of E2f1 and c-Myc mRNA levels with reduced expression of the Pgc-1a/Ppara/Esrrb/g axis and Pink1. This was associated with a significant degree of cardiomyocyte apoptosis, and an inhibition of redox homeostasis and mitochondrial bioenergetics. All these processes are early, Mdm2-associated events and contribute to the development of pathological hypertrophy. Our genetic and biochemical data support a role for Mdm2 in cardiac growth control through the regulation of p53, the Pgc-1 family of transcriptional coactivators and the pivotal antioxidant Pink1.

Differential Proteomics Identifies Reticulocalbin-3 as a Novel Negative Mediator of Collagen Production in Human Cardiac Fibroblasts

Cardiac fibrosis is characterized by an excessive accumulation of extracellular matrix components, including collagens. Galectin-3 (Gal-3) and Cardiotrophin-1 (CT-1) are two profibrotic molecules that mediate Aldosterone (Aldo)-induced cardiac fibrosis. However the underlying mechanisms are not well defined. Our aim is to characterize changes in the proteome of human cardiac fibroblasts treated with Aldo, Gal-3 or CT-1 to identify new common proteins that might be new therapeutic targets in cardiac fibrosis. Using a quantitative proteomic approach in human cardiac fibroblasts, our results show that Aldo, Gal-3 and CT-1 modified the expression of 30, 17 and 89 proteins respectively, being common the reticulocalbin (RCN) family members. RCN-3 down-regulation triggered by Aldo, Gal-3 and CT-1 was verified. Treatment with recombinant RCN-3 decreased collagens expression in human cardiac fibroblasts through Akt phosphorylation. Interestingly, CRISPR/Cas9-mediated activation of RCN-3 decreased collagen production in human cardiac fibroblasts. In addition, recombinant RCN-3 blocked the profibrotic effects of Aldo, Gal-3 and CT-1. Interestingly, RCN-3 blunted the increase in collagens expression induced by other profibrotic stimuli, angiotensin II, in human cardiac fibroblasts. Our results suggest that RCN-3 emerges as a new potential negative regulator of collagen production and could represent a therapeutic target in the context of cardiac fibrosis.

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.

Efficacy and Safety of Renal Sympathetic Denervation on Dogs with Pressure Overload-Induced Heart Failure

BACKGROUND

In dogs with heart failure (HF) induced by overload pressure, the role of renal sympathetic denervation (RSD) on heart failure and in the renal artery is unclear. Therefore, we investigated the efficacy and safety of RSD in dogs with pressure overload-induced heart failure.

METHODS

Twenty mongrel dogs were divided into a sham-operated group, an HF group and an HF + RSD group. In the sham-operated group, the abdominal aorta was located but was not constricted, in the HF group, the abdominal aorta was constricted without RSD, and the HF+RSD group underwent RSD with constriction of the abdominal aorta after 10 weeks. Blood sampling assays, echocardiography, intravascular ultrasound (IVUS) measurement and histopathological examination were performed.

RESULTS

Renal sympathetic denervation caused a significant reduction in the levels of noradrenaline (166.62±6.84 vs. 183.48±13.66 pg/ml, P<0.05), plasma renin activity (1.93±0.12 vs. 2.10±0.13 ng/mlh, P<0.05) and B-type natriuretic peptide (71.14±3.86 vs. 83.15±5.73 pg/ml, P<0.05) at eight weeks after RSD in the HF+RSD group. Compared with the HF group at eight weeks, the left ventricular internal dimension at end-diastole and end-systole were lower and the left ventricular ejection fraction was higher (all P<0.05) at eight weeks after RSD in the HF+RSD group. Intravenous ultrasound images showed no changes in the renal artery lumen, and intimal hyperplasia and vascular lumen stenosis were not observed after RSD.

CONCLUSIONS

Renal sympathetic denervation could improve cardiac function in dogs with HF induced by pressure overload; RSD had no adverse influence on the renal artery.

Influence of Renal Sympathetic Denervation on Cardiac Extracellular Matrix Turnover and Cardiac Fibrosis

BACKGROUND

Renal sympathetic denervation (RSD) represents an effective treatment option for patients with resistant arterial hypertension (HT). Extracellular matrix (ECM) turnover and deposition are essential processes in HT-related cardiovascular remodeling, fibrosis, and cardiac hypertrophy and contribute to hypertensive heart disease.

OBJECTIVES

The primary aim of the present study was to examine the effect of RSD on increased collagen turnover as reflected by serum levels of amino-terminal pro-peptides (PINP, PIIINP) and a carboxyl-terminal pro-peptide (PICP), specific biomarkers for cardiac ECM turnover and cardiovascular fibrosis.

METHODS

A total of 100 consecutive patients (mean age: 65.9±10.1 years) undergoing RSD were included in this study. A therapeutic response was defined as an office systolic blood pressure (SBP) reduction of >10mm Hg 6 months after RSD. Venous serum samples for measurement of PICP, PINP, and PIIINP were collected prior to and 6 months after RSD.

RESULTS

A significant reduction in the office SBP of 24.3 mm Hg (SBP baseline: 166.9±14.3 mm Hg (P < 0.001) was documented 6 months after RSD. At this time point, the serum levels of PICP, PINP, and PIIINP (P < 0.01) were significantly decreased compared to baseline values in patients with an increased collagen turnover, showing significant differences comparing BP responders and nonresponders.

CONCLUSION

In addition to the effective blood pressure reduction in response to RSD, this study demonstrates a positive effect of RSD on biomarkers reflecting cardiovascular ECM turnover and deposition. These results suggest a beneficial effect of RSD on cardiovascular fibrosis, hypertensive heart disease, and end-organ damage in high-risk patients.

Expression patterns of sarcomeric α-actin, α-actinin and UCP2 in the myocardium of Kunming mice after exposure to c-terminal polypeptide of cardiotrophin-1

Cardiotrophin-1 (CT-1) activates a distinct form of cardiac muscle cell hypertrophy in which the sarcomeric units are assembled in series. The aim of the study was to determine the expression pattern of sarcomeric contractile protein α-actin, specialized cytoskeletal protein α-actinin and mitochondrial uncoupling protein-2 (UCP2) in myocardial remodeling induced by chronic exposure to CT-1. Kunming mice were intraperitoneally injected with carboxy-terminal polypeptide (CP) of CT-1 (CT-1-CP, 500 μg·kg(-1)· day(-1)) for 1, 2, 3 and 4 week (s), respectively (4 groups obtained according to the injection time, n=10 each, with 5 males and 5 females in each group). Those injected with physiological saline for 4 weeks served as controls (n=10, with 5 males and 5 females). The heart tissues of mice were harvested at 1, 2, 3 or 4 week (s). Immunohistochemistry (IHC) and Western blotting (WB) were used to detect the distribution and expression of sarcomeric α-actin, α-actinin and mitochondrial UCP2 in myocardial tissues. IHC showed that α-actin was mainly distributed around the nuclei of cardiomyocytes, α-actinin concentrated around the striae and UCP2 scattered rather evenly in the plasma. The expression of α-actin was slightly greater than that of α-actinin and UCP2 in the control group (IHC: χ(2)=6.125; WB: F=0.249, P>0.05) and it gradually decreased after exposure to CT-1-CP. There was no significant difference in the expression of α-actin between the control group and the CT-1-CP-treated groups (χ (2)=7.386, P>0.05). But Western blotting revealed significant difference in the expression of α-actin between the control group and the 4-week CT-1-CP-treated group (F=2.912; q=4.203, P<0.05). Moreover, it was found that the expression of α-actinin increased stepwise with the exposure time in CT-1-CP-treated groups and differed significantly between CT-1-CP-treated groups and the control group (ICH: χ (2)=21.977; WB: F=50.388; P<0.01). The expression of UCP2 was initially increased (WB: control group vs. 1- or 2-week group, q values: 5.603 and 9.995, respectively, P<0.01) and then decreased (WB: control group vs. 3-week group, q=4.742, P<0.01; control group vs. 4-week group, q=0.558, P>0.05). It was suggested that long-term exposure to CT-1-CP could lead to the alteration in the expression of sarcomeric α-actin, α-actinin and mitochondrial UCP2. The different expressions of sarcomeric structure proteins and mitochondrial UCP2 may be involved in myocardial remodeling.

Adrenalectomy reverses myocardial fibrosis in patients with primary aldosteronism

OBJECTIVE

Primary aldosteronism is the most frequent cause of secondary hypertension and is associated with more prominent left ventricular hypertrophy and increased myocardial fibrosis. However, the reversibility of cardiac fibrosis is still unclear. Our objective was to investigate myocardial fibrosis in primary aldosteronism patients and its change after surgery.

METHOD

We prospectively analyzed 20 patients with aldosterone-producing adenoma (APA) who received adrenalectomy from December 2006 to October 2008 and 20 patients with essential hypertension were enrolled as the control group. Plasma carboxy-terminal propeptide of procollagen type I (PICP) determination and echocardiography including ultrasonic tissue characterization by cyclic variation of integrated backscatter (CVIBS) were performed in both groups and 1 year after operation in the APA group.

RESULTS

APA patients had significantly higher SBP and DBP, higher plasma aldosterone concentration (PAC), higher aldosterone-renin ratio (ARR), lower serum potassium levels, and lower plasma renin activity (PRA) than patients with essential hypertension. In echocardiography, APA patients had a higher left ventricular mass index than essential hypertension patients. APA patients had significantly lower CVIBS (6.2 ± 1.5 vs. 8.7 ± 2.0 dB, P < 0.001) and higher plasma PICP levels (107 ± 27 vs. 85 ± 24 μg/l, P = 0.009) than essential hypertension patients. In the correlation study, CVIBS is correlated with log-transformed PRA and log-transformed ARR and PICP is correlated with log-transformed PRA, log-transformed PAC, and log-transformed ARR. One year after adrenalectomy, CVIBS increased significantly (6.2 ± 1.5 to 7.3 ± 1.7 dB, P = 0.033) and plasma PICP levels decreased (107 ± 27 vs. 84 ± 28 μg/l, P = 0.026).

CONCLUSION

Increases in collagen content in the myocardium of APA patients may be reversed by adrenalectomy.

Regulation and role of connective tissue growth factor in AngII-induced myocardial fibrosis

Exposure of rodents to angiotensin II (AngII) is a common model of fibrosis. We have previously shown that cellular infiltration of bone marrow-derived progenitor cells (fibrocytes) occurs before deposition of extracellular matrix and is associated with the production of connective tissue growth factor (CTGF). In the present study, we characterized the role of CTGF in promoting fibrocyte accumulation and regulation after AngII exposure. In animals exposed to AngII using osmotic minipumps (2.0 μg/kg per min), myocardial CTGF mRNA peaked at 6 hours (21-fold; P < 0.01), whereas transforming growth factor-β (TGF-β) peaked at 3 days (fivefold; P < 0.05) compared with saline control. Early CTGF expression occurred before fibrocyte migration (1 day) into the myocardium or ECM deposition (3 days). CTGF protein expression was evident by day 3 of AngII exposure and seemed to be localized to resident cells. Isolated cardiomyocytes and microvascular endothelial cells responded to AngII with increased CTGF production (2.1-fold and 2.8-fold, respectively; P < 0.05), which was abolished with the addition of anti-TGF-β neutralizing antibody. The effect of CTGF on isolated fibrocytes suggested a role in fibrocyte proliferation (twofold; P < 0.05) and collagen production (2.3-fold; P < 0.05). In summary, we provide strong evidence that AngII exposure first resulted in Smad2-dependent production of CTGF by resident cells (6 hours), well before the accumulation of fibrocytes or TGF-β mRNA up-regulation. In addition, CTGF contributes to fibrocyte proliferation in the myocardium and enhances fibrocyte differentiation into a myofibroblast phenotype responsible for ECM deposition.

MMP-2 and sTNF-R1 Variability in Patients with Essential Hypertension: 1-Year Follow-Up Study

The aim of this study is to analyze MMP-2 and sTNF-R1 variability, potent predictors of cardiovascular events, in stable hypertensive patients during a 12-month followup. 234 asymptomatic patients (age 60 ± 13, 136 male) out of 252 patients with essential hypertension were followed up. MMP-2 and sTNF-R1 were measured at baseline and after 12 months (stage I). To compare MMP-2 and sTNF-R1 levels over time interval, we used the statistical method of Bland-Altman. MMP-2 and sTNF-R1 reproducibility was good in our patients for the two intervals with a coefficient of reproducibility of 8.2% and 11.3%, respectively. The percentages of patients within 1.96 × standard deviation of the mean were 93.6% and 92.7%. An elevated coefficient of correlation was obtained for MMP-2, basal versus stage I (r = 0.55, P < 0.0001) and for sTNF-R1 (r = 0.75, P < 0.0001). There is good stability in MMP-2 and sTNF-R1 levels in a followup study of patients with stable hypertension. As a consequence, assessment of its concentrations may be a useful tool for monitoring the follow-up of these patients. Measured variations in MMP-2 and sTNF-R1 levels, exceeding 8.2% and 11.3%, respectively, may indicate an increase in cardiovascular risk, thus, could be used to optimizing treatment than blood pressure control alone.

Cardiac microinjury measured by troponin T predicts collagen metabolism in adults aged >=65 years with heart failure

BACKGROUND

Repeated myocardial microinjuries lead to collagen deposition and fibrosis, thereby increasing the risk of clinical heart failure. Little is known about the longitudinal association between increases in myocardial injury and the biology of collagen synthesis and deposition.

METHODS AND RESULTS

Repeated measures of highly sensitive cardiac troponin T (cTnT) were obtained in participants of the Cardiovascular Health Study (N=353; mean age, 74±6 years; 52% women) at baseline and at 3 years follow-up. Biomarkers of collagen metabolism were obtained at follow-up and included carboxyterminal propeptide of procollagen type I, carboxyterminal telopeptide of type I collagen, and aminoterminal propeptide of procollagen III. Multivariable linear regression analyses were used to examine the association between baseline cTnT and changes in cTnT with collagen metabolism markers at follow-up adjusting for demographics, heart failure status, and cardiovascular risk factors. Results indicated that cTnT increases over 3-years were significantly associated with higher levels of carboxyterminal telopeptide of type I collagen (β=0.22, P<0.001) and aminoterminal propeptide of procollagen III (β=0.12, P=0.035) at follow-up when adjusting for demographic, clinical, and biochemical covariates including baseline cTnT. These associations were stronger in patients with heart failure than in control subjects. Conclusions- Increases in myocardial microinjury measured by changes in cTnT adversely affect markers of collagen metabolism. These findings are important to the biology of myocardial fibrosis and tissue repair. Serial evaluation of cTnT combined with collagen metabolism markers may further elucidate the pathophysiology of heart failure.

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.

Age-related divergent remodeling of the cardiac extracellular matrix in heart failure: collagen accumulation in the young and loss in the aged

The incidence of heart failure (HF) increases with age. This study sought to determine whether aging exacerbates structural and functional remodeling of the myocardium in HF. HF was induced in young (~18 months) and aged sheep (>8 years) by right ventricular tachypacing. In non-paced animals, aging was associated with increased left ventricular (LV) end diastolic internal dimensions (EDID, P<0.001), reduced fractional shortening (P<0.01) and an increase in myocardial collagen content (P<0.01). HF increased EDID and reduced fractional shortening in both young and aged animals, although these changes were more pronounced in the aged (P<0.05). Age-associated differences in cardiac extracellular matrix (ECM) remodeling occurred in HF with collagen accumulation in young HF (P<0.001) and depletion in aged HF (P<0.05). MMP-2 activity increased in the aged control and young HF groups (P<0.05). Reduced tissue inhibitor of metalloproteinase (TIMP) expression (TIMPs 3 and 4, P<0.05) was present only in the aged HF group. Secreted protein acidic and rich in cysteine (SPARC) was increased in aged hearts compared to young controls (P<0.05) while serum procollagen type I C-pro peptide (PICP) was increased in both young failing (P<0.05) and aged failing (P<0.01) animals. In conclusion, collagen content of the cardiac ECM changes in both aging and HF although; whether collagen accumulation or depletion occurs depends on age. Changes in TIMP expression in aged failing hearts alongside augmented collagen synthesis in HF provide a potential mechanism for the age-dependent ECM remodeling. Aging should therefore be considered an important factor when elucidating cardiac disease mechanisms.

Vascular effects of glycoprotein130 ligands--part II: biomarkers and therapeutic targets

Glycoprotein130 (gp130) ligands are defined by the use of the common receptor subunit gp130 and comprise interleukin (IL)-6, oncostatin M (OSM), IL-11, leukemia inhibitory factor (LIF), cardiotrophin-1 (CT-1), cardiotrophin-like cytokine (CLC), ciliary neurotrophic factor (CNTF), IL-27 and neuropoietin (NP). In part I of this review we addressed the pathophysiological functions of gp130 ligands with respect to the vascular wall. In part II of this review on the vascular effects of gp130 ligands we will discuss data about possible use of these molecules as biomarkers to predict development or progression of cardiovascular diseases. Furthermore, the possibility to modulate circulating levels of gp130 ligands or their tissue expression by specific antibodies, soluble gp130 protein, renin-angiotensin-aldosterone system (RASS) inhibitors, statins, agonists of peroxisome proliferator-activated receptors (PPAR), hormone replacement therapy, nonsteroidal anti-inflammatory drugs (NSAID) or lifestyle modulating strategies are presented. Recent knowledge about the application of recombinant cytokines from the gp130 cytokine family as therapeutic agents in obesity or atherosclerosis is also summarized. Thus the purpose of this review is to cover a possible usefulness of gp130 ligands as biomarkers and targets for therapy in cardiovascular pathologies.

Association of imaging markers of myocardial fibrosis with metabolic and functional disturbances in early diabetic cardiomyopathy

BACKGROUND

Metabolic and vascular disturbances contribute to diabetic cardiomyopathy, but the role of interstitial fibrosis in early disease is unproven. We sought to assess the relationship between imaging markers of diffuse fibrosis and myocardial dysfunction and to link this to possible causes of early diabetic cardiomyopathy.

METHODS AND RESULTS

Hemodynamic and metabolic data were measured in 67 subjects with type 2 diabetes mellitus (age 60±10 years) with no cardiac symptoms. Myocardial function was evaluated with standard echocardiography and myocardial deformation; ischemia was excluded by exercise echocardiography. Calibrated integrated backscatter was calculated from parasternal long-axis views. T1 mapping was performed after contrast with a modified Look-Locker technique using saturation recovery images. Amino-terminal propeptides of procollagens type I and III, as well as the carboxy-terminal propeptide of procollagen type I, were assayed to determine collagen turnover. Subjects with abnormal early diastolic tissue velocity (E(m)) had shorter postcontrast T1 values (P=0.042) and higher calibrated integrated backscatter (P=0.007). They were heavier (P=0.003) and had worse exercise capacity (P<0.001), lower insulin sensitivity (P=0.003), and blunted systolic tissue velocity (P=0.05). Postcontrast T1 was associated with diastolic dysfunction (E(m) r=0.28, P=0.020; E/E(m) r=-0.24, P=0.049), impaired exercise capacity (r=0.30, P=0.016), central adiposity (r=-0.26, P=0.046), blood pressure (systolic r=-0.30, P=0.012; diastolic r=-0.49, P<0.001), and insulin sensitivity (r=0.30, P=0.037). The association of T1 with E/E(m) (β=-0.31, P=0.017) was independent of blood pressure and metabolic disturbance. Amino-terminal propeptide of procollagens type III was linked to diastolic dysfunction (E(m) r=-0.32, P=0.008) and calibrated integrated backscatter (r=0.30, P=0.015) but not T1 values.

CONCLUSIONS

The association between myocardial diastolic dysfunction, postcontrast T1 values, and metabolic disturbance supports that diffuse myocardial fibrosis is an underlying contributor to early diabetic cardiomyopathy.

Plasma biomarkers that reflect determinants of matrix composition identify the presence of left ventricular hypertrophy and diastolic heart failure

BACKGROUND

Chronic pressure overload (such as arterial hypertension) may cause left ventricular (LV) remodeling, alterations in cardiac function, and the development of diastolic heart failure. Changes in the composition of the myocardial extracellular matrix may contribute to the development of pressure-overload-induced LV remodeling. We hypothesized that a specific pattern of plasma biomarker expression that reflected changes in these pathophysiological mechanisms would have diagnostic application to identify (1) patients who have development of LV hypertrophy (LVH) and (2) patients with LVH who have development of diastolic heart failure.

METHODS AND RESULTS

Plasma concentration of 17 biomarkers (matrix metalloproteinase [MMP]-1, -2, -3, -7, -8, and -9; tissue inhibitors -1, -2, -3, and -4; N-terminal propeptide of brain natriuretic peptide (NT-proBNP); cardiotrophin; osteopontin; soluble receptor for advanced glycation end products; collagen I teleopeptide; collagen I NT-proBNP; and collagen III N-terminal propetide [PIIINP]), an echocardiogram, and 6-minute hall walk were performed on 241 referent control subjects, 144 patients with LVH but no evidence of heart failure, and 61 patients with LVH and diastolic heart failure (DHF). A plasma multibiomarker panel consisting of increased MMP-7, MMP-9, TIMP-1, PIIINP, and NT-proBNP predicted the presence of LVH with an area under the curve of 0.80. A plasma multibiomarker panel consisting of increased MMP-2, TIMP-4, PIIINP, and decreased MMP-8 predicted the presence of DHF with an area under the curve of 0.79. These multibiomarker panels performed better than any single biomarker including NT-proBNP and better than using clinical covariates alone (area under the curve, 0.73 for LVH and 0.68 for DHF).

CONCLUSIONS

Plasma biomarkers reflecting changes in extracellular matrix fibrillar collagen homeostasis, combined into a multibiomarker panel, have discriminative value in identifying the presence of structural remodeling (LVH) and clinical disease (DHF).

Hypertensive left ventricular hypertrophy risk: beyond adaptive cardiomyocytic hypertrophy

The heart is a remarkably adaptive organ, capable of increasing its minute output and overcoming short-term or prolonged pressure overload. The structural response, in addition to the foregoing functional demands, is that of myocardial hypertrophy. Then, why should an adaptive response increase cardiovascular risk in hypertensive patients with left ventricular hypertrophy (LVH)? Evidence shows that the functional performance of hypertrophied cardiomyocytes is impaired, and that additional alterations develop in cardiomyocytes themselves, the extracellular matrix and the intramyocardial vasculature, leading to myocardial remodelling and providing the basis for the adverse prognosis associated with pathological LVH in hypertensive patients (i.e., hypertensive heart disease, HHD). As molecular information accumulates, the pathophysiological understanding and the clinical approach to HHD are changing. The time has come to develop novel diagnostic and therapeutic strategies aimed at improving the prognosis of HHD on the basis of reversing or even preventing the aforementioned changes in the ventricular myocardium.

Increased levels of oxidative stress, subclinical inflammation, and myocardial fibrosis markers in primary aldosteronism patients

BACKGROUND

Patients with primary aldosteronism experience greater left ventricular hypertrophy and a higher frequency of cardiovascular events than do essential hypertensive patients with comparable blood pressure levels. Aldosterone has been correlated with increased oxidative stress, endothelial inflammation, and fibrosis, particularly in patients with heart disease.

AIM

To evaluate oxidative stress, subclinical endothelial inflammation, and myocardial fibrosis markers in patients with primary aldosteronism and essential hypertension. DESIGN AND INDIVIDUALS: We studied 30 primary aldosteronism patients and 70 control essential hypertensive patients, matched by age, sex and median blood pressure. For all patients, we measured the serum levels of aldosterone, plasma renin activity, malondialdehyde (MDA), xanthine oxidase, metalloproteinase-9, ultrasensitive C-reactive protein and amino terminal propeptides of type I (PINP), and type III procollagen. We also evaluated the effect of PA treatment in 19 PA individuals.

RESULTS

PA patients showed elevated levels of MDA (1.70 ± 0.53 versus 0.94 ± 0.65 μmol/l, P <0.001) and PINP (81.7 ± 50.6 versus 49.7 ± 27 mg/l, P = 0.002) compared with essential hypertensive controls. We found a positive correlation between MDA, PINP, and the serum aldosterone/plasma renin activity ratio in primary aldosteronism patients. Clinically, treating primary aldosteronism patients decreased MDA and PINP levels.

CONCLUSION

We detected higher levels of MDA and PINP in primary aldosteronism patients, suggesting increased oxidative stress and myocardial fibrosis in these individuals. Treating primary aldosteronism patients reduced MDA and PINP levels, which may reflect the direct effect of aldosterone greater than endothelial oxidative stress and myocardial fibrosis, possibly mediated by a mineralocorticoid receptor.

Decompensated heart failure is associated with reduced corin levels and decreased cleavage of pro-atrial natriuretic peptide

BACKGROUND

By promoting salt and water excretion, the corin and the atrial natriuretic peptide (ANP) system should help to maintain fluid balance in heart failure. Yet, the development of fluid retention despite high levels of ANP-related peptides suggests that this compensatory system is limited.

METHODS AND RESULTS

Levels of circulating corin (the pro-ANP-converting enzyme) and pro-ANP were measured in hospitalized patients with heart failure, using novel immunoassays. Patients (n=14) had severe heart failure (New York Heart Association class III-IV) with a median ejection fraction of 18% and median brain natriuretic peptide levels of 1940 pg/mL. In heart failure, median plasma corin levels were 7.6-fold lower than measured in plasma from 16 normal control subjects (180 versus 1368 pg/mL, P<0.01). In contrast, in patients with heart failure, levels of plasma N-terminal ANP peptides (N-ANP and pro-ANP) levels were markedly elevated (42.0 versus 7.5 ng/mL, P<0.01). Levels of uncleaved pro-ANP, measured by novel immunoassays, were significantly higher in patients with heart failure (P<0.01), suggesting that corin cleavage of pro-ANP was impaired. Median plasma levels of cyclic guanosine monophosphate were elevated in patients with heart failure (150.0 versus 7.6 pmol/mL, P<0.01), and plasma cyclic guanosine monophosphate levels positively correlated with the fractional amount of cleaved pro-ANP (r(s)=0.59, P<0.03) but not with levels of uncleaved pro-ANP, implying that the cellular response to ANP remained intact.

CONCLUSIONS

Taken together, these data suggest that there may be patients for whom low corin levels and impaired pro-ANP cleavage contribute to acute decompensation.

Myocardial fibrosis as an early manifestation of hypertrophic cardiomyopathy

BACKGROUND

Myocardial fibrosis is a hallmark of hypertrophic cardiomyopathy and a proposed substrate for arrhythmias and heart failure. In animal models, profibrotic genetic pathways are activated early, before hypertrophic remodeling. Data showing early profibrotic responses to sarcomere-gene mutations in patients with hypertrophic cardiomyopathy are lacking.

METHODS

We used echocardiography, cardiac magnetic resonance imaging (MRI), and serum biomarkers of collagen metabolism, hemodynamic stress, and myocardial injury to evaluate subjects with hypertrophic cardiomyopathy and a confirmed genotype.

RESULTS

The study involved 38 subjects with pathogenic sarcomere mutations and overt hypertrophic cardiomyopathy, 39 subjects with mutations but no left ventricular hypertrophy, and 30 controls who did not have mutations. Levels of serum C-terminal propeptide of type I procollagen (PICP) were significantly higher in mutation carriers without left ventricular hypertrophy and in subjects with overt hypertrophic cardiomyopathy than in controls (31% and 69% higher, respectively; P<0.001). The ratio of PICP to C-terminal telopeptide of type I collagen was increased only in subjects with overt hypertrophic cardiomyopathy, suggesting that collagen synthesis exceeds degradation. Cardiac MRI studies showed late gadolinium enhancement, indicating myocardial fibrosis, in 71% of subjects with overt hypertrophic cardiomyopathy but in none of the mutation carriers without left ventricular hypertrophy.

CONCLUSIONS

Elevated levels of serum PICP indicated increased myocardial collagen synthesis in sarcomere-mutation carriers without overt disease. This profibrotic state preceded the development of left ventricular hypertrophy or fibrosis visible on MRI. (Funded by the National Institutes of Health and others.)

Angiotensin-converting enzyme 2 suppresses pathological hypertrophy, myocardial fibrosis, and cardiac dysfunction

BACKGROUND

Angiotensin-converting enzyme 2 (ACE2) is a pleiotropic monocarboxypeptidase capable of metabolizing several peptide substrates. We hypothesized that ACE2 is a negative regulator of angiotensin II (Ang II)-mediated signaling and its adverse effects on the cardiovascular system.

METHODS AND RESULTS

Ang II infusion (1.5 mg x kg(-1) x d(-1)) for 14 days resulted in worsening cardiac fibrosis and pathological hypertrophy in ACE2 knockout (Ace2(-/y)) mice compared with wild-type (WT) mice. Daily treatment of Ang II-infused wild-type mice with recombinant human ACE2 (rhACE2; 2 mg x kg(-1) x d(-1) IP) blunted the hypertrophic response and expression of hypertrophy markers and reduced Ang II-induced superoxide production. Ang II-mediated myocardial fibrosis and expression of procollagen type I alpha 1, procollagen type III alpha 1, transforming growth factor-beta1, and fibronectin were also suppressed by rhACE2. Ang II-induced diastolic dysfunction was inhibited by rhACE2 in association with reduced plasma and myocardial Ang II and increased plasma Ang 1-7 levels. rhACE2 treatment inhibited Ang II-mediated activation of protein kinase C-alpha and protein kinase C-beta1 protein levels and phosphorylation of the extracellular signal-regulated 1/2, Janus kinase 2, and signal transducer and activator of transcription 3 signaling pathways in wild-type mice. A subpressor dose of Ang II (0.15 mg . kg(-1) . d(-1)) resulted in a milder phenotype that was strikingly attenuated by rhACE2 (2 mg x kg(-1) x d(-1) IP). In adult ventricular cardiomyocytes and cardiofibroblasts, Ang II-mediated superoxide generation, collagen production, and extracellular signal-regulated 1/2 signaling were inhibited by rhACE2 in an Ang 1-7-dependent manner. Importantly, rhACE2 partially prevented the development of dilated cardiomyopathy in pressure-overloaded wild-type mice.

CONCLUSIONS

Elevated Ang II induced hypertension, myocardial hypertrophy, fibrosis, and diastolic dysfunction, which were exacerbated by ACE2 deficiency, whereas rhACE2 attenuated Ang II- and pressure-overload-induced adverse myocardial remodeling. Hence, ACE2 is an important negative regulator of Ang II-induced heart disease and suppresses adverse myocardial remodeling.

Association of serum osteoprotegerin with left ventricular mass in African American adults with hypertension

BACKGROUND

African-Americans with hypertension are susceptible to left ventricular hypertrophy (LVH). Serum osteoprotegerin level has been reported to be associated with LVH. We investigated the association of osteoprotegerin with LV mass (LVM) in 898 African-Americans with hypertension (mean age 65 years, 71% women).

METHODS

Osteoprotegerin levels were measured in serum by an immunoassay and log-transformed for analyses. LVM index (LVMi; LVM/height(2.7)) was estimated using M-mode echocardiography. Linear regression analyses using generalized estimating equations were used to assess the association of osteoprotegerin with LVMi.

RESULTS

Serum osteoprotegerin was correlated with LVMi (r = 0.21; P < 0.0001), an estimated increase in LVMi of 5.05 (95% confidence interval 2.93, 7.17) g/m(2.7) in the highest compared to the lowest osteoprotegerin quartile. This association remained statistically significant after adjustment for conventional cardiovascular risk factors (age, sex, body mass index (BMI), history of smoking, diabetes, systolic blood pressure (BP), total and high-density lipoprotein cholesterol), estimated renal function, history of myocardial infarction and stroke, lifestyle factors (physical activity score, years of education, amount of alcohol consumption), medications (aspirin, antihypertensives, statins, estrogens), and C-reactive protein (CRP) (P = 0.02). Additionally, osteoprotegerin was correlated with early/atrial (E/A) ratio (r = -0.16; P < 0.0001), LV mean wall thickness (r = 0.17; P < 0.0001) and relative wall thickness (r = 0.14; P < 0.0001) but not ejection fraction (r = 0.04; P = 0.24) or internal end-diastolic dimension (r = 0.02; P = 0.60).

CONCLUSION

In African-Americans with hypertension, a higher serum osteoprotegerin level is weakly but independently associated with a higher LVM.