Differential patterns of replacement and reactive fibrosis in pressure and volume overload are related to the propensity for ischaemia and involve resistin

Central role of cardiac fibroblasts in myocardial fibrosis of diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM), a main cardiovascular complication of diabetes, can eventually develop into heart failure and affect the prognosis of patients. Myocardial fibrosis is the main factor causing ventricular wall stiffness and heart failure in DCM. Early control of myocardial fibrosis in DCM is of great significance to prevent or postpone the progression of DCM to heart failure. A growing body of evidence suggests that cardiomyocytes, immunocytes, and endothelial cells involve fibrogenic actions, however, cardiac fibroblasts, the main participants in collagen production, are situated in the most central position in cardiac fibrosis. In this review, we systematically elaborate the source and physiological role of myocardial fibroblasts in the context of DCM, and we also discuss the potential action and mechanism of cardiac fibroblasts in promoting fibrosis, so as to provide guidance for formulating strategies for prevention and treatment of cardiac fibrosis in DCM.

The right ventricle in tetralogy of Fallot: adaptation to sequential loading

Right ventricular dysfunction is a major determinant of outcome in patients with complex congenital heart disease, as in tetralogy of Fallot. In these patients, right ventricular dysfunction emerges after initial pressure overload and hypoxemia, which is followed by chronic volume overload due to pulmonary regurgitation after corrective surgery. Myocardial adaptation and the transition to right ventricular failure remain poorly understood. Combining insights from clinical and experimental physiology and myocardial (tissue) data has identified a disease phenotype with important distinctions from other types of heart failure. This phenotype of the right ventricle in tetralogy of Fallot can be described as a syndrome of dysfunctional characteristics affecting both contraction and filling. These characteristics are the end result of several adaptation pathways of the cardiomyocytes, myocardial vasculature and extracellular matrix. As long as the long-term outcome of surgical correction of tetralogy of Fallot remains suboptimal, other treatment strategies need to be explored. Novel insights in failure of adaptation and the role of cardiomyocyte proliferation might provide targets for treatment of the (dysfunctional) right ventricle under stress.

Resistin and risks of incident heart failure subtypes and cardiac fibrosis: the Multi-Ethnic Study of Atherosclerosis

AIMS

Resistin is a circulating inflammatory biomarker that is associated with cardiovascular disease. We investigated the associations of resistin and incident heart failure (HF) and its subtypes, as well as specific measures of subclinical HF (myocardial fibrosis and relevant biomarkers).

METHODS

We analysed data from 1968 participants in the Multi-Ethnic Study of Atherosclerosis with measurements of plasma resistin levels at clinic visits from 2002 to 2005. Participants were subsequently followed for a median of 10.5 years for HF events. The associations between resistin levels and incident HF, HF with reduced ejection fraction (HFrEF), and HF with preserved ejection fraction (HFpEF) were examined using multivariable Cox proportional hazards models. Linear regression models assessed the associations between resistin levels and myocardial fibrosis from cardiac magnetic resonance imaging, as well as hs-cTnT and NT-proBNP.

RESULTS

The mean age of the cohort was 64.7 years, and 50.0% were female. Seventy-four participants (4%) developed incident HF during follow-up. In a Cox proportional hazards model adjusted for age, gender, education level, race/ethnicity, and traditional risk factors, higher resistin levels were significantly associated with incident HF (HR 1.44, CI 1.18-1.75, P = 0.001) and HFrEF (HR 1.47, CI 1.07-2.02, P = 0.016), but not with HFpEF (HR 1.25, CI 0.89-1.75, P = 0.195). Resistin levels showed no significant associations with myocardial fibrosis, NT-proBNP, or hs-cTnT levels.

CONCLUSIONS

In a multi-ethnic cohort free of cardiovascular disease at baseline, elevated resistin levels were associated with incident HF, more prominently with incident HFrEF than HFpEF, but not with subclinical myocardial fibrosis or biomarkers of HF.

Heme is involved in the exogenous ALA-promoted growth and antioxidant defense system of cucumber seedlings under salt stress

A biosynthetic precursor of tetrapyrrol, 5-aminolevulinic acid (ALA), is widely used in agricultural production, as an exogenous regulatory substance that effectively regulates plant growth. Previous studies have shown that heme and chlorophyll accumulate in plants under salt stress, when treated with exogenous ALA. In this study, we explored the regulatory role of heme in plants, by spraying 25 mg L^-1 ALA onto the leaves of cucumber seedlings treated with heme synthesis inhibitor (2,2'-dipyridyl, DPD) and heme scavenger (hemopexin, Hx), under 50 mmol L^-1 NaCl stress. The results showed that NaCl alone and DPD + Hx treatments to cucumber seedlings subjected to salt stress adversely affected their growth, by decreasing biomass accumulation, root activity, and root morphology. In addition, these treatments induced an increase in membrane lipid oxidation, as well as enhancement of anti-oxidase activities, proline content, and glutamate betaine. However, exogenous ALA application increased the plant growth and root architecture indices under NaCl stress, owing to a lack of heme in the seedlings. In addition, cucumber seedlings treated with DPD and Hx showed inhibition of growth under salt stress, but exogenous ALA effectively improved cucumber seedling growth as well as the physiological characteristics; moreover, the regulation of ALA in plants was weakened when heme synthesis was inhibited. Heme biosynthesis and metabolism genes, HEMH and HO1, which are involved in the ALA metabolic pathway, were upregulated under salinity conditions, when ferrochelatase activity was inhibited. Application of exogenous ALA increased the heme content in the leaves. Thus, exogenous ALA may supplement the substrates for heme synthesis. These results indicated that heme plays a vital role in the response of plants to salinity stress. In conclusion, heme is involved in ALA-mediated alleviation of damage caused to cucumber seedlings and acts as a positive regulator of plant adaption.

Resistin deletion protects against heart failure injury by targeting DNA damage response

AIMS

Increased resistin (Retn) levels are associated with development of cardiovascular diseases. However, the role of Retn in heart failure (HF) is still unclear. Here we probed the functional and molecular mechanism underlying the beneficial effect of Retn deletion in HF.

METHODS AND RESULTS

Wild-type (WT) and adipose tissue-specific Retn-knockout (RKO) mice were subjected to transverse aortic constriction (TAC)-induced HF. Cardiac function and haemodynamic changes were measured by echocardiography and left ventricular catheterization. Adipose tissue Retn deletion attenuated while Retn cardiac-selective overexpression, via a recombinant adeno-associated virus-9 vector, exacerbated TAC-induced hypertrophy, cardiac dysfunction, and myocardial fibrosis in WT and RKO mice. Mechanistically, we showed that Gadd45α was significantly increased in RKO HF mice while cardiac overexpression of Retn led to its downregulation. miR148b-3p directly targets Gadd45α and inhibits its expression. Retn overexpression upregulated miR148b-3p expression and triggered DNA damage response (DDR) in RKO-HF mice. Inhibition of miR148b-3p in vivo normalized Gadd45α expression, decreased DDR, and reversed cardiac dysfunction and fibrosis. In vitro Retn overexpression in adult mouse cardiomyocytes activated miR148b-3p and reduced Gadd45α expression. Gadd45α overexpression in H9C2-cardiomyoblasts protected against hydrogen peroxide- and Retn-induced DDR.

CONCLUSION

These findings reveal that diminution in circulating Retn reduced myocardial fibrosis and apoptosis, and improved heart function in a mouse model of HF, at least in part, through attenuation of miR148b-3p and DDR. The results of this study indicate that controlling Retn levels may provide a potential therapeutic approach for treating pressure overload-induced HF.

FIBER-ML, an Open-Source Supervised Machine Learning Tool for Quantification of Fibrosis in Tissue Sections

Pathologic fibrosis is a major hallmark of tissue insult in many chronic diseases. Although the amount of fibrosis is recognized as a direct indicator of the extent of disease, there is no consentaneous method for its quantification in tissue sections. This study tested FIBER-ML, a semi-automated, open-source freeware that uses a machine-learning approach to quantify fibrosis automatically after a short user-controlled learning phase. Fibrosis was quantified in sirius red-stained tissue sections from two fibrogenic animal models: acute stress-induced cardiomyopathy in rats (Takotsubo syndrome-like) and HIV-induced nephropathy in mice (chronic kidney disease). The quantitative results of FIBER-ML software version 1.0 were compared with those of ImageJ in Takotsubo syndrome, and with those of inForm in chronic kidney disease. Intra- and inter-operator and inter-software correlation and agreement were assessed. All correlations were excellent (>0.95) in both data sets. The values of discriminatory power between the pathologic and healthy groups were <10^-3 for data on Takotsubo syndrome and <10^-4 for data on chronic kidney disease. Intra-operator agreement, assessed by intra-class coefficient correlation, was good (>0.8), while inter-operator and inter-software agreement ranged from moderate to good (>0.7). FIBER-ML performed in a fast and user-friendly manner, with reproducible and consistent quantification of fibrosis in tissue sections. It offers an open-source alternative to currently used software, including quality control and file management.

Molecules linked to Ras signaling as therapeutic targets in cardiac pathologies

Abstract

The Ras family of small Guanosine Triphosphate (GTP)-binding proteins (G proteins) represents one of the main components of intracellular signal transduction required for normal cardiac growth, but is also critically involved in the development of cardiac hypertrophy and heart failure. The present review provides an update on the role of the H-, K- and N-Ras genes and their related pathways in cardiac diseases. We focus on cardiac hypertrophy and heart failure, where Ras has been studied the most. We also review other cardiac diseases, like genetic disorders related to Ras. The scope of the review extends from fundamental concepts to therapeutic applications. Although the three Ras genes have a nearly identical primary structure, there are important functional differences between them: H-Ras mainly regulates cardiomyocyte size, whereas K-Ras regulates cardiomyocyte proliferation. N-Ras is the least studied in cardiac cells and is less associated to cardiac defects. Clinically, oncogenic H-Ras causes Costello syndrome and facio-cutaneous-skeletal syndromes with hypertrophic cardiomyopathy and arrhythmias. On the other hand, oncogenic K-Ras and alterations of other genes of the Ras-Mitogen-Activated Protein Kinase (MAPK) pathway, like Raf, cause Noonan syndrome and cardio-facio-cutaneous syndromes characterized by cardiac hypertrophy and septal defects. We further review the modulation by Ras of key signaling pathways in the cardiomyocyte, including: (i) the classical Ras-Raf-MAPK pathway, which leads to a more physiological form of cardiac hypertrophy; as well as other pathways associated with pathological cardiac hypertrophy, like (ii) The SAPK (stress activated protein kinase) pathways p38 and JNK; and (iii) The alternative pathway Raf-Calcineurin-Nuclear Factor of Activated T cells (NFAT). Genetic alterations of Ras isoforms or of genes in the Ras-MAPK pathway result in Ras-opathies, conditions frequently associated with cardiac hypertrophy or septal defects among other cardiac diseases. Several studies underline the potential role of H- and K-Ras as a hinge between physiological and pathological cardiac hypertrophy, and as potential therapeutic targets in cardiac hypertrophy and failure.

Graphic abstract

The Ras (Rat Sarcoma) gene family is a group of small G proteins

Ras is regulated by growth factors and neurohormones affecting cardiomyocyte growth and hypertrophy

Ras directly affects cardiomyocyte physiological and pathological hypertrophy

Genetic alterations of Ras and its pathways result in various cardiac phenotypes

Ras and its pathway are differentially regulated in acquired heart disease

Ras modulation is a promising therapeutic target in various cardiac conditions.

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.

Regional Replacement and Diffuse Interstitial Fibrosis in Aortic Regurgitation: Prognostic Implications From Cardiac Magnetic Resonance

OBJECTIVES

This study used cardiac magnetic resonance (CMR) to assess left ventricular (LV) remodeling in chronic aortic regurgitation (AR) to identify both forms of myocardial fibrosis and examine its association with clinical outcomes.

BACKGROUND

Chronic AR leads to LV remodeling, which is associated with 2 forms of myocardial fibrosis: regional replacement fibrosis that is directly imaged by late gadolinium enhancement (LGE) CMR; and diffuse interstitial fibrosis, which can be inferred by T1 mapping techniques.

METHODS

Patients with chronic AR who were undergoing contrast CMR with T1 mapping for valve assessment from 2011 to 2018 were enrolled. Patients with a confounding etiology of myocardial fibrosis were excluded. In addition to quantification of AR severity and LV volumetrics, LGE and T1 mapping pre- and post-contrast were performed to measure extracellular volume (ECV) and indexed ECV (iECV). Patients were followed up longitudinally to assess for the composite event of death and the need for aortic valve replacement.

RESULTS

A total of 177 patients with isolated chronic AR were included (66% males, median age 58 years [47.0 years-68.0 years]) with a median follow up of 2.5 years (1.07 years-3.56 years). The iECV significantly increased with AR severity (P < 0.001), whereas ECV and replacement fibrosis did not (P = NS). On multivariate analysis, iECV remained associated with the composite event (P = 0.01). On Kaplan-Meier analysis stratified by AR regurgitant fraction (RF) and iECV, patients with AR RF severity ≥30% and iECV ≥24 mL/m² demonstrated the highest event rate.

CONCLUSIONS

Among CMR biomarkers of fibrosis, iECV was more closely associated than replacement fibrosis or ECV with survival free of aortic valve replacement.

Resistin induces cardiac fibroblast-myofibroblast differentiation through JAK/STAT3 and JNK/c-Jun signaling

Cardiac fibrosis is characterized by excessive deposition of extracellular matrix proteins and myofibroblast differentiation. Our previous findings have implicated resistin in cardiac fibrosis; however, the molecular mechanisms underlying this process are still unclear. Here we investigated the role of resistin in fibroblast-to-myofibroblast differentiation and elucidated the pathways involved in this process. Fibroblast-to-myofibroblast transdifferentiation was induced with resistin or TGFβ1 in NIH-3T3 and adult cardiac fibroblasts. mRNA and protein expression of fibrotic markers were analyzed by qPCR and immunoblotting. Resistin-knockout mice, challenged with a high-fat diet (HFD) for 20 weeks to stimulate cardiac impairment, were analyzed for cardiac function and fibrosis using histologic and molecular methods. Cardiac fibroblasts stimulated with resistin displayed increased fibroblast-to-myofibroblast conversion, with increased levels of αSma, col1a1, Fn, Ccn2 and Mmp9, with remarkable differences in the actin network appearance. Mechanistically, resistin promotes fibroblast-to-myofibroblast transdifferentiation and fibrogenesis via JAK2/STAT3 and JNK/c-Jun signaling pathways, independent of TGFβ1. Resistin-null mice challenged with HFD showed an improvement in cardiac function and a decrease in tissue fibrosis and reduced mRNA levels of fibrogenic markers. These findings are the first to delineate the role of resistin in the process of cardiac fibroblast-to-myofibroblast differentiation via JAK/STAT3 and JNK/c-Jun pathways, potentially leading to stimulation of cardiac fibrosis.

Boron improves cardiac contractility and fibrotic remodeling following myocardial infarction injury

Myocardial fibrosis is a major determinant of clinical outcomes in heart failure (HF) patients. It is characterized by the emergence of myofibroblasts and early activation of pro-fibrotic signaling pathways before adverse ventricular remodeling and progression of HF. Boron has been reported in recent years to augment the innate immune system and cell proliferation, which play an important role in the repair and regeneration of the injured tissue. Currently, the effect of boron on cardiac contractility and remodeling is unknown. In this study, we investigated, for the first time, the effect of boron supplementation on cardiac function, myocardial fibrosis, apoptosis and regeneration in a rat model myocardial infarction (MI)-induced HF. MI was induced in animals and borax, a sodium salt of boron, was administered for 7 days, p.o., 21 days post-injury at a dose level of 4 mg/kg body weight. Transthoracic echocardiographic analysis showed a significant improvement in systolic and diastolic functions with boron treatment compared to saline control. In addition, boron administration showed a marked reduction in myocardial fibrosis and apoptosis in the injured hearts, highlighting a protective effect of boron in the ischemic heart. Interestingly, we observed a tenfold increase of nuclei in thin myocardial sections stained positive for the cell cycle marker Ki67 in the MI boron-treated rats compared to saline, indicative of increased cardiomyocyte cell cycle activity in MI hearts, highlighting its potential role in regeneration post-injury. We similarly observed increased Ki67 and BrdU staining in cultured fresh neonatal rat ventricular cardiomyocytes. Collectively, the results show that boron positively impacted MI-induced HF and attenuated cardiac fibrosis and apoptosis, two prominent features of HF. Importantly, boron has the potential to induce cardiomyocyte cell cycle entry and potentially cardiac tissue regeneration after injury. Boron might be beneficial as a supplement in MI and may be a good candidate substance for anti-fibrosis approach.

Pro-inflammatory Cytokines in Acute Coronary Syndromes

BACKGROUND

Over the last decades, the role of inflammation and immune system activation in the initiation and progression of coronary artery disease (CAD) has been established.

OBJECTIVES

The study aimed to present the interplay between cytokines and their actions preceding and shortly after ACS.

METHODS

We searched in a systemic manner the most relevant articles to the topic of inflammation, cytokines, vulnerable plaque and myocardial infarction in MEDLINE, COCHRANE and EMBASE databases.

RESULTS

Different classes of cytokines (intereleukin [IL]-1 family, Tumor necrosis factor-alpha (TNF-α) family, chemokines, adipokines, interferons) are implicated in the entire process leading to destabilization of the atherosclerotic plaque, and consequently, to the incidence of myocardial infarction. Especially IL-1 and TNF-α family are involved in inflammatory cell accumulation, vulnerable plaque formation, platelet aggregation, cardiomyocyte apoptosis and adverse remodeling following the myocardial infarction. Several cytokines such as IL-6, adiponectin, interferon-γ, appear with significant prognostic value in ACS patients. Thus, research interest focuses on the modulation of inflammation in ACS to improve clinical outcomes.

CONCLUSION

Understanding the unique characteristics that accompany each cytokine-cytokine receptor interaction could illuminate the signaling pathways involved in plaque destabilization and indicate future treatment strategies to improve cardiovascular prognosis in ACS patients.

Experimental models of cardiac physiology and pathology

Experimental models of cardiac disease play a key role in understanding the pathophysiology of the disease and developing new therapies. The features of the experimental models should reflect the clinical phenotype, which can have a wide spectrum of underlying mechanisms. We review characteristics of commonly used experimental models of cardiac physiology and pathophysiology in all translational steps including in vitro, small animal, and large animal models. Understanding their characteristics and relevance to clinical disease is the key for successful translation to effective therapies.

Phosphorylation of GATA4 at serine 105 is required for left ventricular remodelling process in angiotensin II-induced hypertension in rats

In this study, we investigated whether local intramyocardial GATA4 overexpression affects the left ventricular (LV) remodelling process and the importance of phosphorylation at serine 105 (S105) for the actions of GATA4 in an angiotensin II (AngII)‐induced hypertension rat model. Adenoviral constructs overexpressing wild‐type GATA4 or GATA4 mutated at S105 were delivered into the anterior LV free wall. AngII (33.3 µg/kg/h) was administered via subcutaneously implanted minipumps. Cardiac function and structure were examined by echocardiography, followed by histological immunostainings of LV sections and gene expression measurements by RT‐qPCR. The effects of GATA4 on cultured neonatal rat ventricular fibroblasts were evaluated. In AngII‐induced hypertension, GATA4 overexpression repressed fibrotic gene expression, reversed the hypertrophic adult‐to‐foetal isoform switch of myofibrillar genes and prevented apoptosis, whereas histological fibrosis was not affected. Overexpression of GATA4 mutated at S105 resulted in LV chamber dilatation, cardiac dysfunction and had minor effects on expression of myocardial remodelling genes. Fibrotic gene expression in cardiac fibroblasts was differently affected by overexpression of wild‐type or mutated GATA4. Our results indicate that GATA4 reduces AngII‐induced responses by interfering with pro‐fibrotic and hypertrophic gene expressions. GATA4 actions on LV remodelling and fibroblasts are dependent on phosphorylation site S105.

A role for calcium in resistin transcriptional activation in diabetic hearts

The adipokine resistin has been proposed to link obesity, insulin resistance and diabetes. We have previously reported that diabetic hearts express high levels of resistin while overexpression of resistin in adult rat hearts gives rise to a phenotype resembling diabetic cardiomyopathy. The transcriptional regulation of resistin in diabetic cardiac tissue is currently unknown. This study investigated the mechanism of resistin upregulation and the role of Serca2a in its transcriptional suppression. We demonstrate that restoration of Ca²⁺ homeostasis in diabetic hearts, through normalization of Serca2a function genetically and pharmacologically, suppressed resistin expression via inhibition of NFATc. H9c2 myocytes stimulated with high-glucose concentration or Ca²⁺ time-dependently increased NFATc and resistin expression while addition of the Ca²⁺ chelator BAPTA-AM attenuated this effect. NFATc expression was enhanced in hearts from ob/ob diabetic and from cardiac-specific Serca2a^−/− mice. Similarly, NFATc increased resistin expression in myocytes cultured in low glucose while the NFATc inhibitor VIVIT blocked glucose-induced resistin expression, suggesting that hyperglycemia/diabetes induces resistin expression possibly through NFATc activation. Interestingly, overexpression of Serca2a or VIVIT mitigated glucose-stimulated resistin and NFATc expression and enhanced AMPK activity, a downstream target of resistin signaling. NFATc direct activation of resistin was verified by resistin promoter luciferase activity and chromatin-immunoprecipitation analysis. Interestingly, activation of Serca2a by a novel agonist, CDN1163, mirrored the effects of AAV9-Serca2a gene transfer on resistin expression and its promoter activity and AMPK signaling in diabetic mice. These findings parse a role for Ca²⁺ in resistin transactivation and provide support that manipulation of Serca2a-NFATc-Resistin axis might be useful in hyper-resistinemic conditions.

Assessment of myocardial fibrosis by late gadolinium enhancement imaging and biomarkers of collagen metabolism in chronic rheumatic mitral regurgitation

Background

In chronic rheumatic mitral regurgitation (CRMR), involvement of the myocardium in the rheumatic process has been controversial. Therefore, we sought to study the presence of fibrosis using late gadolinium enhancement cardiac magnetic resonance imaging (LGE–CMR) and biomarkers of collagen turnover in CRMR.

Methods

Twenty–two patients with CRMR underwent CMR and echocardiography. Serum concentrations of matrix metalloproteinase– 1 (MMP–1), tissue inhibitor of MMP–1 (TIMP– 1), MMP–1–to–TIMP–1 ratio, procollagen III N–terminal pro–peptide (PIIINP) and procollagen type IC peptide (PIP) were measured.

Results

Four patients had fibrosis on LGE–CMR. PIP and PIIINP concentrations were similar to those of the controls, however MMP–1 concentration was increased compared to that of the controls (log MMP–1 3.5 ± 0.7 vs 2.7 ± 0.9, p = 0.02). There was increased MMP–1 activity as the MMP–1–to– TIMP–1 ratio was higher in CRMR patients compared to the controls (–1.2 ± 0.6 vs –2.1 ± 0.89, p = 0.002).

Conclusion

Myocardial fibrosis was rare in CRMR patients. CRMR is likely a disease characterised by the predominance of collagen degradation rather than increased synthesis and myocardial fibrosis.

Nestin expression is upregulated in the fibrotic rat heart and is localized in collagen-expressing mesenchymal cells and interstitial CD31(+)- cells

Renal and lung fibrosis was characterized by the accumulation of collagen-immunoreactive mesenchymal cells expressing the intermediate filament protein nestin. The present study tested the hypothesis that nestin expression was increased in the hypertrophied/fibrotic left ventricle of suprarenal abdominal aorta constricted adult male Sprague-Dawley rats and induced in ventricular fibroblasts by pro-fibrotic peptide growth factors. Nestin protein levels were upregulated in the pressure-overloaded left ventricle and expression positively correlated with the rise of mean arterial pressure. In sham and pressure-overloaded hearts, nestin immunoreactivity was detected in collagen type I(+)-and CD31(+)-cells identified in the interstitium and perivascular region whereas staining was absent in smooth muscle α-actin(+)-cells. A significantly greater number of collagen type I(+)-cells co-expressing nestin was identified in the left ventricle of pressure-overloaded rats. Moreover, an accumulation of nestin(+)-cells lacking collagen, CD31 and smooth muscle α-actin staining was selectively observed at the adventitial region of predominantly large calibre blood vessels in the hypertrophied/fibrotic left ventricle. Angiotensin II and TGF-β1 stimulation of ventricular fibroblasts increased nestin protein levels via phosphatidylinositol 3-kinase- and protein kinase C/SMAD3-dependent pathways, respectively. CD31/eNOS(+)-rat cardiac microvascular endothelial cells synthesized/secreted collagen type I, expressed prolyl 4-hydroxylase and TGF-β1 induced nestin expression. The selective accumulation of adventitial nestin(+)-cells highlighted a novel feature of large vessel remodelling in the pressure-overloaded heart and increased appearance of collagen type I/nestin(+)-cells may reflect an activated phenotype of ventricular fibroblasts. CD31/collagen/nestin(+)-interstitial cells could represent displaced endothelial cells displaying an unmasked mesenchymal phenotype, albeit contribution to the reactive fibrotic response of the pressure-overloaded heart remains unknown.

Resistin Gene Expression is Downregulated in CD4(+) T Helper Lymphocytes and CD14(+) Monocytes in Rheumatoid Arthritis Responding to TNF-α Inhibition

Rheumatoid arthritis (RA) is caused by complex interactions between immune cells and sustained by Th1 response cytokines. Resistin [resistance to insulin; (RETN)] is an inflammatory cytokine, first discovered in murine adipocytes. In man, RETN is mainly secreted by monocytes. The distinct role of RETN in the immune reaction is uncertain; however, RETN has pro-inflammatory, pro-fibrotic and possibly tolerogenic properties. The aim was to assess the reaction of RETN gene expression to TNF-α inhibition (I) in pathogenetic immune cell subsets in RA, in the context of Th1, inflammatory and regulatory cytokine gene expressions. Accordingly, we measured RETN, IFN-γ, TNF-β, IL-1β, TNF-α, TGF-β and IL-10 gene expressions in CD14(+) monocytes, CD4(+) T helper (Th) lymphocytes (ly), CD8(+) T cytotoxic (Tc) ly and CD19(+) B ly in active RA before and 3 months after start of TNF-αI. Leucocyte subsets were separated by specific monoclonal antibody-covered beads, RNA extracted and levels of RETN, Th1 response, inflammatory and regulatory cytokine mRNAs measured by quantitative reverse transcription-polymerase chain reaction technique. We found that TNF-αI caused a significant downregulation of RETN gene expression in CD14(+) monocytes and CD4(+) Th ly and was unchanged in CD8(+) Tc ly and CD19(+) B ly. Both in active RA and during TNF-αI, RETN mRNA levels were significantly higher in CD14(+) monocytes than in all other examined cell types. In monocytes, fold change in RETN and TGF-β gene expressions upon TNF-αI correlated significantly. Our findings indicate that RETN has pro-inflammatory as well as proresolving roles in active RA.

Can the onset of heart failure be delayed by treating diabetic cardiomyopathy?

The pathophysiology of diabetic cardiomyopathy (DC) is not fully understood. This frequently undiagnosed complication of chronic hyperglycemia leads to heart failure (HF). However, it is suggested that an appropriate metabolic control of diabetes at an early stage of this deleterious disease, is able to inhibit the development and progression of DC to HF. Recently, it has been postulated that myocardial ischaemia plays an important role in the development of this pathology. Results of the antianginal pharmacological treatment and revascularization are unsatisfactory and reveal a gap in our knowledge and current approaches to treating DC. Most recent studies emphasize the ischaemic component of DC as a key target for therapeutic strategies, which could change its unfavorable history. More stress is put on an early diagnosis of coronary artery disease (CAD), promoting prompt revascularization. Choosing the accurate time of surgical revascularization, with the inclusion of the metabolic background, can ensure complete revascularization with better prognosis. This review will focus on the complexity of DC and summarize contemporary knowledge of treatment strategies for patients with diabetes and CAD.

Diabetic cardiomyopathy: is resistin a culprit?

Cardiovascular disease, including heart failure (HF), is the major cause of death in patients with diabetes. A contributing factor to the occurrence of HF in such patients is the development of diabetic cardiomyopathy. Recent evidence demonstrates that perturbations associated with adipokines secretion and signaling result in lusitropic and inotropic defects in diabetic cardiomyopathy. This perspective editorial will discuss the central role of resistin, a recently discovered adipokine, in the maladaptive cardiac phenotype seen in diabetic hearts. Given the pleiotropic effects of resistin, strategies targeting the control of resistin levels may constitute a potentially viable therapeutic utility in patients with diabetes and diabetes-induced cardiovascular diseases.

Connective tissue growth factor regulates cardiac function and tissue remodeling in a mouse model of dilated cardiomyopathy

Cardiac structural changes associated with dilated cardiomyopathy (DCM) include cardiomyocyte hypertrophy and myocardial fibrosis. Connective tissue growth factor (CTGF) has been associated with tissue remodeling and is highly expressed in failing hearts. Our aim was to test if inhibition of CTGF would alter the course of cardiac remodeling and preserve cardiac function in the protein kinase Cε (PKCε) mouse model of DCM. Transgenic mice expressing constitutively active PKCε in cardiomyocytes develop cardiac dysfunction that was evident by 3 months of age, and that progressed to cardiac fibrosis, heart failure, and increased mortality. Beginning at 3 months of age, PKCε mice were treated with a neutralizing monoclonal antibody to CTGF (FG-3149) for an additional 3 months. CTGF inhibition significantly improved left ventricular (LV) systolic and diastolic functions in PKCε mice, and slowed the progression of LV dilatation. Using gene arrays and quantitative PCR, the expression of many genes associated with tissue remodeling was elevated in PKCε mice, but significantly decreased by CTGF inhibition. However total collagen deposition was not attenuated. The observation of significantly improved LV function by CTGF inhibition in PKCε mice suggests that CTGF inhibition may benefit patients with DCM. Additional studies to explore this potential are warranted.

Activation of common signaling pathways during remodeling of the heart and the bladder

The heart and the urinary bladder are hollow muscular organs, which can be afflicted by pressure overload injury due to pathological conditions such as hypertension and bladder outlet obstruction. This increased outflow resistance induces hypertrophy, marked by dramatic changes in the organs' phenotype and function. The end result in both the heart and the bladder can be acute organ failure due to advanced fibrosis and the subsequent loss of contractility. There is emerging evidence that microRNAs (miRNAs) play an important role in the pathogenesis of heart failure and bladder dysfunction. MiRNAs are endogenous non-coding single-stranded RNAs, which regulate gene expression and control adaptive and maladaptive organ remodeling processes. This Review summarizes the current knowledge of molecular alterations in the heart and the bladder and highlights common signaling pathways and regulatory events. The miRNA expression analysis and experimental target validation done in the heart provide a valuable source of information for investigators working on the bladder and other organs undergoing the process of fibrotic remodeling. Aberrantly expressed miRNA are amendable to pharmacological manipulation, offering an opportunity for development of new therapies for cardiac and bladder hypertrophy and failure.

Resistin: insulin resistance to malignancy

Adipose tissue is recognized as an endocrine organ that secretes bioactive substances known as adipokines. Excess adipose tissue and adipose tissue dysfunction lead to dysregulated adipokine production that can contribute to the development of obesity-related co-morbidities. Among the various adipokines, resistin, which was initially considered as a determinant of the emergence of insulin resistance in obesity, has appeared as an important link between obesity and inflammatory processes. Several experimental and clinical studies have suggested an association between increased resistin levels and severe conditions associated with obesity such as cardiovascular disease and malignancies. In this review, we present the growing body of evidence that human resistin is an inflammatory biomarker and potential mediator of obesity-associated diseases. A common pathway seems to involve the combined alteration of immune and inflammatory processes that favor metabolic disturbances, atherosclerosis and carcinogenesis. The mode of action and the signaling pathways utilized by resistin in its interactions with target cells could involve oxidative and nitrosative stress. Therefore, resistin could function as a key molecule in the complications of obesity development and could potentially be used as a diagnostic and prognostic marker.

A static pressure sensitive receptor APJ promote H9c2 cardiomyocyte hypertrophy via PI3K-autophagy pathway

This study is designed to investigate whether APJ receptor acts as a sensor in static pressure-induced cardiomyocyte hypertrophy and to investigate the mechanism of PI3K-autophagy pathway. The left ventricular hypertrophy rat model was established by coarctation of abdominal aorta. H9c2 rat cardiomyocytes were cultured in the presence of static pressure which was given by a custom-made pressure incubator. The results revealed that the expression of apelin/APJ system, PI3K, Akt and their phosphorylation were significantly increased in the operation group. Static pressure up-regulated the APJ expression, PI3K phosphorylation, Akt phosphorylation, LC3-II/I and beclin-1 expression in cardiomyocytes. APJ shRNA pGPU6/Neo-rat-399, PI3K inhibitor LY294002, Akt inhibitor 1701-1 blocked the up-regulation of APJ, PI3K phosphorylation, Akt phosphorylation, LC3-II/I and beclin-1 expression, respectively. Moreover, static pressure increased the diameter, volume, protein content of cells, and these could be reversed when the cells were treated with pGPU6/Neo-rat-399, LY294002, and autophagy inhibitor 3-methyladenine, respectively. These results suggested that static pressure up-regulates APJ expression to promote cardiomyocyte hypertrophy by a PI3K-autophagy pathway.