Cardiac fibrosis in the ageing heart: Contributors and mechanisms

In vitro characterization of radiofrequency ablation lesions in equine and swine myocardial tissue

Radiofrequency ablation is a promising technique for arrhythmia treatment in horses. Due to the thicker myocardial wall and higher blood flow in horses, it is unknown if conventional radiofrequency settings used in human medicine can be extrapolated to horses. The study aim is to describe the effect of ablation settings on lesion dimensions in equine myocardium. To study species dependent effects, results were compared to swine myocardium. Right ventricular and right and left atrial equine myocardium and right ventricular swine myocardium were suspended in a bath with circulating isotonic saline at 37 °C. The ablation catheter delivered radiofrequency energy at different-power-duration combinations with a contact force of 20 g. Lesion depth and width were measured and lesion volume was calculated. Higher power or longer duration of radiofrequency energy delivery increased lesion size significantly in the equine atrial myocardium and in equine and swine ventricular myocardium (P < 0.001). Mean lesion depth in equine atrial myocardium ranged from 2.9 to 5.5 mm with a diameter ranging from 6.9 to 10.1 mm. Lesion diameter was significantly larger in equine tissue compared to swine tissue (P = 0.020). Obtained data in combination with estimated wall thickness can improve lesion transmurality which might reduce arrhythmia recurrence. Optimal ablation settings may differ between species.

Unveiling the role of TRPA1 in cardiovascular health and disease: a mini review

The transient receptor potential ankyrin 1 (TRPA1) ion channel has emerged as significant regulators of cardiovascular physiology and pathology. TRPA1 is a non-selective cation channel permeable to calcium ions. A unique feature of the channel is its function as a sensor of various temperature, chemical and mechanical stimuli, while it can also be activated by endogenous inflammatory mediators and reactive oxygen species. Over the last two decades, much progress has been made in illuminating the role of TRPA1 in the regulation of cardiovascular physiology and pathophysiology in addition to its important function in pain sensation. This review provides a comprehensive analysis of recent studies investigating the involvement of TRPA1 channels in various cardiovascular diseases, including myocardial infarction, ischemia-reperfusion injury, myocardial fibrosis, and response to environmental toxins. We discuss the diverse roles of TRPA1 channels in cardiac pathology and highlight their potential as therapeutic targets for cardiovascular disorders. Moreover, we explore the challenges and opportunities linked with targeting TRPA1 channels for treating cardiovascular diseases, alongside future research directions.

BRD4: an effective target for organ fibrosis

Fibrosis is an excessive wound-healing response induced by repeated or chronic external stimuli to tissues, significantly impacting quality of life and primarily contributing to organ failure. Organ fibrosis is reported to cause 45% of all-cause mortality worldwide. Despite extensive efforts to develop new antifibrotic drugs, drug discovery has not kept pace with the clinical demand. Currently, only pirfenidone and nintedanib are approved by the FDA to treat pulmonary fibrotic illness, whereas there are currently no available antifibrotic drugs for hepatic, cardiac or renal fibrosis. The development of fibrosis is closely related to epigenetic alterations. The field of epigenetics primarily studies biological processes, including chromatin modifications, epigenetic readers, DNA transcription and RNA translation. The bromodomain and extra-terminal structural domain (BET) family, a class of epigenetic readers, specifically recognizes acetylated histone lysine residues and promotes the formation of transcriptional complexes. Bromodomain-containing protein 4 (BRD4) is one of the most well-researched proteins in the BET family. BRD4 is implicated in the expression of genes related to inflammation and pro-fibrosis during fibrosis. Inhibition of BRD4 has shown promising anti-fibrotic effects in preclinical studies; however, no BRD4 inhibitor has been approved for clinical use. This review introduces the structure and function of BET proteins, the research progress on BRD4 in organ fibrosis, and the inhibitors of BRD4 utilized in fibrosis. We emphasize the feasibility of targeting BRD4 as an anti-fibrotic strategy and discuss the therapeutic potential and challenges associated with BRD4 inhibitors in treating fibrotic diseases.

Targeting SIRT2 in Aging-Associated Fibrosis Pathophysiology

Aging is a complex biological process that involves multi-level structural and physiological changes. Aging is a major risk factor for many chronic diseases. The accumulation of senescent cells changes the tissue microenvironment and is closely associated with the occurrence and development of tissue and organ fibrosis. Fibrosis is the result of dysregulated tissue repair response in the development of chronic inflammatory diseases. Recent studies have clearly indicated that SIRT2 is involved in regulating the progression of fibrosis, making it a potential target for anti-fibrotic drugs. SIRT2 is a NAD+ dependent histone deacetylase, shuttling between nucleus and cytoplasm, and is highly expressed in liver, kidney and heart, playing an important role in the occurrence and development of aging and fibrosis. Therefore, we summarized the role of SIRT2 in liver, kidney and cardiac fibrosis during aging.

The autonomic nerves around the vein of Marshall: a postmortem study with clinical implications

This study aims to analyze the vein of Marshall (VOM) in human autopsy hearts and its correlation with clinical data to elucidate the morphological substrates of atrial fibrillation (AF) and other cardiac diseases. Twenty-three adult autopsy hearts were studied, assessing autonomic nerves by immunohistochemistry with tyrosine hydroxylase (sympathetic nerves), choline acetyltransferase (parasympathetic nerves), growth-associated protein 43 (neural growth), and S100 (general neural marker) antibodies. Interstitial fibrosis was assessed by Masson trichrome staining. Measurements were conducted via morphometric software. The results were correlated with clinical data. Sympathetic innervation was abundant in all VOM-adjacent regions. Subjects with a history of AF, cardiovascular cause of death, and histologically verified myocardial infarction had increased sympathetic innervation and neural growth around the VOM at the mitral isthmus. Interstitial fibrosis increased with age and heart weight was associated with AF and cardiovascular cause of death. This study increases our understanding of the cardiac autonomic innervation in the VOM area in various diseases, offering implications for the development of new therapeutic approaches targeting the autonomic nervous system.

The Senescent Heart-"Age Doth Wither Its Infinite Variety"

Cardiovascular diseases are a leading cause of morbidity and mortality world-wide. While many factors like smoking, hypertension, diabetes, dyslipidaemia, a sedentary lifestyle, and genetic factors can predispose to cardiovascular diseases, the natural process of aging is by itself a major determinant of the risk. Cardiac aging is marked by a conglomerate of cellular and molecular changes, exacerbated by age-driven decline in cardiac regeneration capacity. Although the phenotypes of cardiac aging are well characterised, the underlying molecular mechanisms are far less explored. Recent advances unequivocally link cardiovascular aging to the dysregulation of critical signalling pathways in cardiac fibroblasts, which compromises the critical role of these cells in maintaining the structural and functional integrity of the myocardium. Clearly, the identification of cardiac fibroblast-specific factors and mechanisms that regulate cardiac fibroblast function in the senescent myocardium is of immense importance. In this regard, recent studies show that Discoidin domain receptor 2 (DDR2), a collagen-activated receptor tyrosine kinase predominantly located in cardiac fibroblasts, has an obligate role in cardiac fibroblast function and cardiovascular fibrosis. Incisive studies on the molecular basis of cardiovascular aging and dysregulated fibroblast function in the senescent heart would pave the way for effective strategies to mitigate cardiovascular diseases in a rapidly growing elderly population.

The pro-resolving mediator, annexin A1 regulates blood pressure, and age-associated changes in cardiovascular function and remodeling

Aging is associated with chronic, low-level inflammation which may contribute to cardiovascular pathologies such as hypertension and atherosclerosis. This chronic inflammation may be opposed by endogenous mechanisms to limit inflammation, for example, by the actions of annexin A1 (ANXA1), an endogenous glucocorticoid-regulated protein that has anti-inflammatory and pro-resolving activity. We hypothesized the pro-resolving mediator ANXA1 protects against age-induced changes in blood pressure (BP), cardiovascular structure and function, and cardiac senescence. BP was measured monthly in conscious mature (4-month) and middle-aged (12-month) ANXA1-deficient (ANXA1-/- ) and wild-type C57BL/6 mice. Body composition was measured using EchoMRI, and both cardiac and vascular function using ultrasound imaging. Cardiac hypertrophy, fibrosis and senescence, vascular fibrosis, elastin, and calcification were assessed histologically. Gene expression relevant to structural remodeling, inflammation, and cardiomyocyte senescence were also quantified. In C57BL/6 mice, progression from 4 to 12 months of age did not affect the majority of cardiovascular parameters measured, with the exception of mild cardiac hypertrophy, vascular calcium, and collagen deposition. Interestingly, ANXA1-/- mice exhibited higher BP, regardless of age. Additionally, age progression had a marked impact in ANXA1-/- mice, with markedly augmented vascular remodeling, impaired vascular distensibility, and body composition. Consistent with vascular dysfunction, cardiac dysfunction, and hypertrophy were also evident, together with markers of senescence and inflammation. These findings suggest that endogenous ANXA1 plays a critical role in regulating BP, cardiovascular function, and remodeling and delays cardiac senescence. Our findings support the development of novel ANXA1-based therapies to prevent age-related cardiovascular pathologies.

Nur77 alleviates cardiac fibrosis by upregulating GSK-3β transcription during aging

Cardiac fibrosis is associated with aging, for which no targeted therapies are available. With aging, the levels of nerve growth factor-induced gene B (Nur77) are reduced during cardiac remodelling; however, its role in cardiac fibrosis in aging remains unclear. Here, we found that Nur77 knockout increased cardiac structure abnormalities, systolic and diastolic dysfunction, cardiac hypertrophy, and fibrotic marker expression in 15-month-old mice. Furthermore, Nur77 deficiency induced collagen type I (Col-1) and α-smooth muscle actin overproduction in transforming growth factor beta (TGF-β) treated H9c2 cells, whereas Nur77 overexpression attenuated this effect. Nur77 deficiency in vivo and in vitro downregulated glycogen synthase kinase (GSK)-3β expression and increased β-catenin activity, while its overexpression increased GSK-3β expression. GSK-3β knockdown counteracted the anti-fibrotic effect of Nur77 on TGF-β-treated H9c2 cells. Chromatin immunoprecipitation and luciferase reporter assay results suggested GSK-3β as the direct target of Nur77. Our findings suggest that Nur77 directly initiates GSK-3β transcription and age-related cardiac fibrosis partly through the GSK-3β/β-catenin pathway. This study proposes a novel mechanism for Nur77 regulating cardiac fibrosis and suggests Nur77 as a target for the prevention and treatment of aging-associated cardiac fibrosis and heart failure.

Nucleosome assembly protein 1 like 1 (NAP1L1) promotes cardiac fibrosis by inhibiting YAP1 ubiquitination and degradation

Myocardial fibrosis post myocardial infarction (MI) is characterized by abnormal extracellular matrix (ECM) deposition and cardiac dysfunction could finally develop into serious heart disease, like heart failure. Lots of regulating factors involved in this pathological process have been reported while the specific mediators and underlying mechanisms remain to need to be further investigated. As part of the NAP1 family, Nucleosome assembly protein 1 like 1 (NAP1L1) is expressed in a wide variety of tissues. Here, we report that NAP1L1 is a significant regulator of cardiac fibrosis and is upregulated in ischemic cardiomyopathy patient hearts. Enhanced expression of NAP1L1 can promote cardiac fibroblasts (CFs) proliferation, migration, and differentiation into myofibroblasts. In contrast, loss of NAP1L1 decreased fibrosis-related mRNA and protein levels, inhibited the trans-differentiation, and blunted migration and proliferation of CFs after Transforming Growth Factorβ1（TGF-β1）stimulation. In vivo, NAP1L1 knockout mice enhanced cardiac function and reduced fibrosis area in response to MI stimuli. Mechanically, NAP1L1 binding to Yes-associated protein 1 (YAP1) protein influences its stability, and silencing NAP1L1 can inhibit YAP1 expression by promoting its ubiquitination and degradation in CFs. Collectively, NAP1L1 could potentially be a new therapeutic target for various cardiac disorders, including myocardial fibrosis.

Epigenetic Regulation of Fibroblasts and Crosstalk between Cardiomyocytes and Non-Myocyte Cells in Cardiac Fibrosis

Epigenetic mechanisms and cell crosstalk have been shown to play important roles in the initiation and progression of cardiac fibrosis. This review article aims to provide a thorough overview of the epigenetic mechanisms involved in fibroblast regulation. During fibrosis, fibroblast epigenetic regulation encompasses a multitude of mechanisms, including DNA methylation, histone acetylation and methylation, and chromatin remodeling. These mechanisms regulate the phenotype of fibroblasts and the extracellular matrix composition by modulating gene expression, thereby orchestrating the progression of cardiac fibrosis. Moreover, cardiac fibrosis disrupts normal cardiac function by imposing myocardial mechanical stress and compromising cardiac electrical conduction. This review article also delves into the intricate crosstalk between cardiomyocytes and non-cardiomyocytes in the heart. A comprehensive understanding of the mechanisms governing epigenetic regulation and cell crosstalk in cardiac fibrosis is critical for the development of effective therapeutic strategies. Further research is warranted to unravel the precise molecular mechanisms underpinning these processes and to identify potential therapeutic targets.

Antisenescence Therapy Improves Function in a Human Model of Cardiac Fibrosis-on-a-Chip

Cardiac fibrosis is a significant contributor to heart failure and is characterized by abnormal ECM deposition and impaired contractile function. We have previously developed a model of cardiac fibrosis via TGF-β treatment of engineered microtissues using heart-on-a-chip technology which incorporates human induced pluripotent stem cell-derived cardiomyocytes and cardiac fibroblasts. Here, we describe that these cardiac fibrotic tissues expressed markers associated with cellular senescence via transcriptomic analysis. Treatment of fibrotic tissues with the senolytic drugs dasatinib and quercetin (D+Q) led to an improvement of contractile function, reduced passive tension, and downregulated senescence-related gene expression, an outcome we were previously unable to achieve using standard-of-care drugs. The improvement in functional parameters was also associated with a reduction in fibroblast density, though no changes in absolute collagen deposition were observed. This study demonstrates the benefit of senolytic treatment for cardiac fibrosis in a human-relevant model, supporting data in animal models, and will enable the further elucidation of cell-specific effects of senolytics and how they impact cardiac fibrosis and senescence.

Late Effects of Chronic Low Dose Rate Total Body Irradiation on the Heart Proteome of ApoE-/- Mice Resemble Premature Cardiac Ageing

Recent epidemiologic studies support an association between chronic low-dose radiation exposure and the development of cardiovascular disease (CVD). The molecular mechanisms underlying the adverse effect of chronic low dose exposure are not fully understood. To address this issue, we have investigated changes in the heart proteome of ApoE deficient (ApoE^-/-) C57Bl/6 female mice chronically irradiated for 300 days at a very low dose rate (1 mGy/day) or at a low dose rate (20 mGy/day), resulting in cumulative whole-body doses of 0.3 Gy or 6.0 Gy, respectively. The heart proteomes were compared to those of age-matched sham-irradiated ApoE^-/- mice using label-free quantitative proteomics. Radiation-induced proteome changes were further validated using immunoblotting, enzyme activity assays, immunohistochemistry or targeted transcriptomics. The analyses showed persistent alterations in the cardiac proteome at both dose rates; however, the effect was more pronounced following higher dose rates. The altered proteins were involved in cardiac energy metabolism, ECM remodelling, oxidative stress, and ageing signalling pathways. The changes in PPARα, SIRT, AMPK, and mTOR signalling pathways were found at both dose rates and in a dose-dependent manner, whereas more changes in glycolysis and ECM remodelling were detected at the lower dose rate. These data provide strong evidence for the possible risk of cardiac injury following chronic low dose irradiation and show that several affected pathways following chronic irradiation overlap with those of ageing-associated heart pathology.

Accelerated ageing and coronary microvascular dysfunction in chronic heart failure in Tgαq*44 mice

Age represents a major risk factor in heart failure (HF). However, the mechanisms linking ageing and HF are not clear. We aimed to identify the functional, morphological and transcriptomic changes that could be attributed to cardiac ageing in a model of slowly progressing HF in Tgαq*44 mice in reference to the cardiac ageing process in FVB mice. In FVB mice, ageing resulted in the impairment of diastolic cardiac function and in basal coronary flow (CF), perivascular and interstitial fibrosis without changes in the cardiac activity of angiotensin-converting enzyme (ACE) or aldosterone plasma concentration. In Tgαq*44 mice, HF progression was featured by the impairment of systolic and diastolic cardiac function and in basal CF that was associated with a distinct rearrangement of the capillary architecture, pronounced perivascular and interstitial fibrosis, progressive activation of cardiac ACE and systemic angiotensin-aldosterone-dependent pathways. Interestingly, cardiac ageing genes and processes were represented in Tgαq*44 mice not only in late but also in early phases of HF, as evidenced by cardiac transcriptome analysis. Thirty-four genes and 8 biological processes, identified as being ageing related, occurred early and persisted along HF progression in Tgαq*44 mice and were mostly associated with extracellular matrix remodelling and fibrosis compatible with perivascular fibrosis resulting in coronary microvascular dysfunction (CMD) in Tgαq*44 mice. In conclusion, accelerated and persistent cardiac ageing contributes to the pathophysiology of chronic HF in Tgαq*44 mice. In particular, prominent perivascular fibrosis of microcirculation resulting in CMD represents an accelerated cardiac ageing phenotype that requires targeted treatment in chronic HF.

Activation of Kir2.1 improves myocardial fibrosis by inhibiting Ca 2+ overload and the TGF-β1/Smad signaling pathway

The inwardly rectifying potassium channel Kir2.1 is closely associated with many cardiovascular diseases. However, the effect and mechanism of Kir2.1 in diabetic cardiomyopathy remain unclear. In vivo, we use STZ to establish the model, and ventricular structural changes, myocardial inflammatory infiltration, and myocardial fibrosis severity are detected by echocardiography, histological staining, immunohistochemistry, and western blot analysis, respectively. In vitro, a myocardial fibrosis model is established with high glucose. The Kir2.1 current amplitude, intracellular calcium concentration, fibrosis-related proteins, and TGF-β1/Smad pathway proteins are detected by whole-cell patch clamp, calcium probes, western blot analysis, and immunofluorescence, respectively. The in vivo results show that compared to diabetic cardiomyopathy, zacopride (a Kir2.1 selective agonist) significantly reduces the left ventricular systolic diameter and diastolic diameter, increases the left ventricular ejection fraction and left ventricular short-axis shortening, improves the degree of cell necrosis, and reduces the expression of myocardial interstitial fibrosis protein and collagen fibre deposition area. The in vitro results show that the current amplitude and protein expression of Kir2.1 are both decreased in the high glucose-induced myocardial fibrosis model. Additionally, zacopride significantly upregulates the expression of Kir2.1 and inhibits the expressions of the fibrosis-related proteins α-SMA, collagen I, and collagen III. Activation of Kir2.1 reduces the intracellular calcium concentration and inhibits the protein expressions of TGF-β1 and p-Smad 2/3. Activation of Kir2.1 can improve myocardial fibrosis induced by diabetic cardiomyopathy, and the possible mechanism may be related to inhibiting Ca ²⁺ overload and the TGF-β1/Smad signaling pathway.

Mitochondrial miRNA as epigenomic signatures: Visualizing aging-associated heart diseases through a new lens

Aging bears many hard knocks, but heart disorders earn a particular allusion, being the most widespread. Cardiovascular diseases (CVDs) are becoming the biggest concern to mankind due to sundry health conditions directly or indirectly related to heart-linked abnormalities. Scientists know that mitochondria play a critical role in the pathophysiology of cardiac diseases. Both environment and genetics play an essential role in modulating and controlling mitochondrial functions. Even a minor abnormality may prove detrimental to heart function. Advanced age combined with an unhealthy lifestyle can cause most cardiomyocytes to be replaced by fibrotic tissue which upsets the conducting system and leads to arrhythmias. An aging heart encounters far more heart-associated comorbidities than a young heart. Many state-of-the-art technologies and procedures are already being used to prevent and treat heart attacks worldwide. However, it remains a mystery when this heart bomb would explode because it lacks an alarm. This calls for a novel and effective strategy for timely diagnosis and a sure-fire treatment. This review article provides a comprehensive overture of prospective potentials of mitochondrial miRNAs that predict complicated and interconnected pathways concerning heart ailments and signature compilations of relevant miRNAs as biomarkers to plot the role of miRNAs in epigenomics. This article suggests that analysis of DNA methylation patterns in age-associated heart diseases may determine age-impelled biomarkers of heart disease.

Sex-Mediated Differences in TNF Signaling- and ECM-Related Gene Expression in Aged Rat Kidney

Aging leads to the functional decline of an organism, which is associated with age and sex. To understand the functional change of kidneys depending on age and sex, we carried out a transcriptome analysis using RNA sequencing (RNA-Seq) data from rat kidneys. Four differentially expressed gene (DEG) sets were generated according to age and sex, and Gene Ontology analysis and overlapping analysis of Kyoto Encyclopedia of Genes and Genomes pathways were performed for the DEG sets. Through the analysis, we revealed that inflammation- and extracellular matrix (ECM)-related genes and pathways were upregulated in both males and females during aging, which was more prominent in old males than in old females. Furthermore, quantitative real-time PCR analysis confirmed that the expression of tumor necrosis factor (TNF) signaling-related genes, Birc3, Socs3, and Tnfrsf1b, and ECM-related genes, Cd44, Col3a1, and Col5a2, which showed that the genes were markedly upregulated in males and not females during aging. Also, hematoxylin-eosin (H&E) staining for histological analysis showed that renal damage was highly shown in old males rather than old females. In conclusion, in the rat kidney, the genes involved in TNF signaling and ECM accumulation are upregulated in males more than in females during aging. These results suggest that the upregulation of the genes may have a higher contribution to age-related kidney inflammation and fibrosis in males than in females.

Clostridium butyricum and Bifidobacterium pseudolongum Attenuate the Development of Cardiac Fibrosis in Mice

Cardiac fibrosis is an integral aspect of every form of cardiovascular diseases, which is one of the leading causes of death worldwide. It is urgent to explore new effective drugs and treatments. In this paper, transverse aortic constriction (TAC)-induced cardiac fibrosis was significantly alleviated by a cocktail of antibiotics to clear the intestinal flora, indicating that the gut microbiota was associated with the disease process of cardiac fibrosis. We transplanted feces from sham-operated and TAC-treated mice to mice treated with a cocktail of antibiotics. We found that TAC-treated gut microbiota dysbiosis cannot cause cardiac fibrosis on its own. Interestingly, healthy fecal microbiota transplantation could alleviate cardiac fibrosis, indicating that targeted probiotics and related metabolite intervention may restore a normal microenvironment for the treatment or prevention of cardiac fibrosis. We used 16S rRNA sequencing of fecal samples and discovered that butyric acid-producing bacteria and Bifidobacterium pseudolongum were the dominant bacteria in the group with the lowest degree of cardiac fibrosis. Moreover, we demonstrated that sodium butyrate prevented the development of cardiac fibrosis. The effect of Clostridium butyricum (butyric acid-producing bacteria) was better than that of B. pseudolongum on cardiac fibrosis. Surprisingly, the cocktail of two probiotics had a stronger ability than a single probiotic. In conclusion, therapies targeting the gut microbiota and metabolites such as probiotics present new strategies for treating cardiovascular disease. IMPORTANCE Cardiac fibrosis is a basic process in cardiac remodeling. It is related to almost all types of cardiovascular diseases (CVD) and has become an important global health problem. Basic research and a number of clinical studies have shown that myocardial fibrosis can be prevented and reversed to a certain extent. It is urgent to explore new effective drugs and treatments. We indicated a causal relationship between cardiac fibrosis and gut microbiota. Gut microbiota dysbiosis cannot cause cardiac fibrosis on its own. Interestingly, healthy fecal microbiota transplantation could alleviate cardiac fibrosis. According to our findings, the combined use of butyric acid-producing bacteria and B. pseudolongum can help prevent cardiac fibrosis. Therapies targeting the gut microbiota and metabolites, such as probiotics, represent new strategies for treating cardiovascular disease.

Genetic Disruption of Guanylyl Cyclase/Natriuretic Peptide Receptor-A Triggers Differential Cardiac Fibrosis and Disorders in Male and Female Mutant Mice: Role of TGF-β1/SMAD Signaling Pathway

The global targeted disruption of the natriuretic peptide receptor-A (NPRA) gene (Npr1) in mice provokes hypertension and cardiovascular dysfunction. The objective of this study was to determine the mechanisms regulating the development of cardiac fibrosis and dysfunction in Npr1 mutant mice. Npr1 knockout (Npr1^-/-, 0-copy), heterozygous (Npr1^+/-, 1-copy), and wild-type (Npr1^+/+, 2-copy) mice were treated with the transforming growth factor (TGF)-β1 receptor (TGF-β1R) antagonist GW788388 (2 µg/g body weight/day; ip) for 28 days. Hearts were isolated and used for real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), Western blot, and immunohistochemical analyses. The Npr1^-/- (0-copy) mice showed a 6-fold induction of cardiac fibrosis and dysfunction with markedly induced expressions of collagen-1α (3.8-fold), monocyte chemoattractant protein (3.7-fold), connective tissue growth factor (CTGF, 5.3-fold), α-smooth muscle actin (α-SMA, 6.1-fold), TGF-βRI (4.3-fold), TGF-βRII (4.7-fold), and phosphorylated small mothers against decapentaplegic (pSMAD) proteins, including pSMAD-2 (3.2-fold) and pSMAD-3 (3.7-fold), compared with wild-type mice. The expressions of phosphorylated extracellular-regulated kinase ERK1/2 (pERK1/2), matrix metalloproteinases-2, -9, (MMP-2, -9), and proliferating cell nuclear antigen (PCNA) were also significantly upregulated in Npr1 0-copy mice. The treatment of mutant mice with GW788388 significantly blocked the expression of fibrotic markers, SMAD proteins, MMPs, and PCNA compared with the vehicle-treated control mice. The treatment with GW788388 significantly prevented cardiac dysfunctions in a sex-dependent manner in Npr1 0-copy and 1-copy mutant mice. The results suggest that the development of cardiac fibrosis and dysfunction in mutant mice is predominantly regulated through the TGF-β1-mediated SMAD-dependent pathway.

Sacubitril/valsartan reduces indications for arrhythmic primary prevention in heart failure with reduced ejection fraction: insights from DISCOVER-ARNI, a multicenter Italian register

Aims

This sub-study deriving from a multicentre Italian register [Deformation Imaging by Strain in Chronic Heart Failure Over Sacubitril-Valsartan: A Multicenter Echocardiographic Registry (DISCOVER)-ARNI] investigated whether sacubitril/valsartan in addition to optimal medical therapy (OMT) could reduce the rate of implantable cardioverter-defibrillator (ICD) indications for primary prevention in heart failure with reduced ejection fraction (HFrEF) according to European guidelines indications, and its potential predictors.

Methods and results

In this observational study, consecutive patients with HFrEF eligible for sacubitril/valsartan from 13 Italian centres were included. Lack of follow-up or speckle tracking data represented exclusion criteria. Demographic, clinical, biochemical, and echocardiographic data were collected at baseline and after 6 months from sacubitril/valsartan initiation. Of 351 patients, 225 (64%) were ICD carriers and 126 (36%) were not ICD carriers (of whom 13 had no indication) at baseline. After 6 months of sacubitril/valsartan, among 113 non-ICD carriers despite having baseline left ventricular (LV) ejection fraction (EF) ≤ 35% and New York Heart Association (NYHA) class = II-III, 69 (60%) did not show ICD indications; 44 (40%) still fulfilled ICD criteria. Age, atrial fibrillation, mitral regurgitation > moderate, left atrial volume index (LAVi), and LV global longitudinal strain (GLS) significantly varied between the groups. With receiver operating characteristic curves, age ≥ 75 years, LAVi ≥ 42 mL/m2 and LV GLS ≥-8.3% were associated with ICD indications persistence (area under the curve = 0.65, 0.68, 0.68, respectively). With univariate and multivariate analysis, only LV GLS emerged as significant predictor of ICD indications at follow-up in different predictive models.

Conclusions

Sacubitril/valsartan may provide early improvement of NYHA class and LVEF, reducing the possible number of implanted ICD for primary prevention in HFrEF. Baseline reduced LV GLS was a strong marker of ICD indication despite OMT. Early therapy with sacubitril/valsartan may save infective/haemorrhagic risks and unnecessary costs deriving from ICDs.

The Contribution of the Interleukin-4-Induced Epithelial Cell Senescence to Glandular Fibrosis in IgG4-Related Sialadenitis

OBJECTIVE

Immunoglobulin G4-related sialadenitis (IgG4-RS) is a chronic fibro-inflammatory disease characterized by glandular fibrosis and hyposalivation. Here we aimed to explore the role of cellular senescence in the pathogenesis of IgG4-RS-related fibrosis.

METHODS

The expression of senescence markers and proinflammatory cytokines in the submandibular glands (SMGs) of IgG4-RS patients (n = 18) and controls (n = 14) was determined by proteomics, real-time polymerase chain reaction (PCR), western blot, and immunohistochemistry. After interleukin-4 (IL-4) treatment, high-throughput RNA-sequencing was performed to identify the differentially expressed genes in SMG-C6 cells. A glandular fibrosis model was established by the intraglandular injection of IL-4 into mouse SMGs (n = 8 per group).

RESULTS

Salivary acinar and ductal epithelial cells underwent senescence in IgG4-RS patients, as indicated by the elevated activity of senescence-associated β-galactosidase, lipofuscin accumulation, enhanced expression of senescence markers (p53 and p16^INK4A ), and upregulation of senescence-associated secretory phenotype factors. Moreover, there was a significant increase in IL-4 levels in SMGs of IgG4-RS patients, which positively correlated with p16^INK4A expression and the fibrosis score. Incubation with IL-4 exacerbated salivary epithelial cell senescence by increasing the expression of p16^INK4A through ROS-p38 mitogen-activated protein kinase (MAPK) pathway. The supernatant collected from IL-4-induced senescent SMG-C6 cells enhanced fibroblast activation and matrix protein production. Furthermore, injecting IL-4 promoted fibrosis and senescence phenotypes in the SMGs in vivo.

CONCLUSION

The cellular senescence induced by IL-4 through the ROS-p38 MAPK-p16^INK4A pathway promoted fibrogenesis during IgG4-RS. Our data suggest that cellular senescence could serve as a novel therapeutic target for treating IgG4-RS.

LOX-1 Deletion Attenuates Myocardial Fibrosis in the Aged Mice, Particularly Those With Hypertension

Background: Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a transmembrane glycoprotein that mediates uptake of oxidized low-density lipoprotein (ox-LDL) into cells. Previous studies had shown that LOX-1 deletion had a potential to inhibit cardiac fibrosis in mouse models of hypertension and myocardial infarction. Whether LOX-1 deletion also affects cardiac fibrosis associated with aging still remains unknown. The aim of this study was to investigate the effect of LOX-1 deletion on myocardial fibrosis in the aged mice.

Methods: C57BL/6 mice and LOX-1 knockout (KO) mice with C57BL/6 background were studied to the age of 60 weeks. Both genotypes of aged mice were exposed to angiotensin II (Ang II) or saline for additional 4 weeks. The mice were then sacrificed, and myocardial fibrosis, reactive oxygen species (ROS) and expression of LOX-1, fibronectin, collagens, p22^phox, and gp91^phox were measured.

Results: LOX-1 deletion markedly reduced Ang II-mediated rise of blood pressure in the aged mice (vs. saline-treated mice). LOX-1 deletion also limited fibrosis and decreased fibronectin and collagen-3 expression in the hearts of aged mice, but not the expression of collagen-1 and collagen-4. LOX-1 deletion also inhibited ROS production and p22^phox expression. As the aged mice were exposed to Ang II for 4 weeks (resulting in hypertension), LOX-1 deletion more pronounced inhibiting myocardial fibrosis and ROS production, and decreasing expression of fibronectin, collagen-1, collagen-2, collagen-3, p22^phox, and gp91^phox.

Conclusion: LOX-1 deletion limited fibrosis and ROS production in the hearts of aged mice. This effect was more pronounced in the aged mice with hypertension induced by Ang II infusion.

Fibroageing: An ageing pathological feature driven by dysregulated extracellular matrix-cell mechanobiology

Ageing is a multifactorial biological process leading to a progressive decline of physiological functions. The process of ageing includes numerous changes in the cells and the interactions between cell-cell and cell-microenvironment remaining as a critical risk factor for the development of chronic degenerative diseases. Systemic inflammation, known as inflammageing, increases as a consequence of ageing contributing to age-related morbidities. But also, persistent and uncontrolled activation of fibrotic pathways, with excessive accumulation of extracellular matrix (ECM) and organ dysfunction is markedly more frequent in the elderly. In this context, we introduce here the concept of Fibroageing, that is, the propensity to develop tissue fibrosis associated with ageing, and propose that ECM is a key player underlying this process. During ageing, molecules of the ECM become damaged through many modifications including glycation, crosslinking, and accumulation, leading to matrix stiffness which intensifies ageing-associated alterations. We provide a framework with some mechanistic hypotheses proposing that stiff ECM, in addition to the well-known activation of fibrotic positive feedback loops, affect several of the hallmarks of ageing, such as cell senescence and mitochondrial dysfunction, and in this context, is a key mechanism and a driver thread of Fibroageing.

Traditional Chinese medicine as a therapeutic option for cardiac fibrosis: Pharmacology and mechanisms

Cardiovascular diseases are one of the leading causes of death worldwide and cardiac fibrosis is a common pathological process for cardiac remodeling in cardiovascular diseases. Cardiac fibrosis not only accelerates the deterioration progress of diseases but also becomes a pivotal contributor for futile treatment in clinical cardiovascular trials. Although cardiac fibrosis is common and prevalent, effective medicines to provide sufficient clinical intervention for cardiac fibrosis are still unavailable. Traditional Chinese medicine (TCM) is the natural essence experienced boiling, fry, and other processing methods, including active ingredients, extracts, and herbal formulas, which have been applied to treat human diseases for a long history. Recently, research has increasingly focused on the great potential of TCM for the prevention and treatment of cardiac fibrosis. Here, we aim to clarify the identified pro-fibrotic mechanisms and intensively summarize the application of TCM in improving cardiac fibrosis by working on these mechanisms. Through comprehensively analyzing, TCM mainly regulates the following pathways during ameliorating cardiac fibrosis: attenuation of inflammation and oxidative stress, inhibition of cardiac fibroblasts activation, reduction of extracellular matrix accumulation, modulation of the renin-angiotensin-aldosterone system, modulation of autophagy, regulation of metabolic-dependent mechanisms, and targeting microRNAs. We also discussed the deficiencies and the development direction of anti-fibrotic therapies on cardiac fibrosis. The data reviewed here demonstrates that TCM shows a robust effect on alleviating cardiac fibrosis, which provides us a rich source of new drugs or drug candidates. Besides, we also hope this review may give some enlightenment for treating cardiac fibrosis in clinical practice.

Cardiac Dysfunction in a Mouse Vascular Dementia Model of Bilateral Common Carotid Artery Stenosis

Background: Cardiac function is associated with cognitive function. Previously, we found that stroke and traumatic brain injury evoke cardiac dysfunction in mice. In this study, we investigate whether bilateral common carotid artery stenosis (BCAS), a model that induces vascular dementia (VaD) in mice, induces cardiac dysfunction. Methods: Late-adult (6-8 months) C57BL/6J mice were subjected to sham surgery (n = 6) or BCAS (n = 8). BCAS was performed by applying microcoils (0.16 mm internal diameter) around both common carotid arteries. Cerebral blood flow and cognitive function tests were performed 21-28 days post-BCAS. Echocardiography was conducted in conscious mice 29 days after BCAS. Mice were sacrificed 30 days after BCAS. Heart tissues were isolated for immunohistochemical evaluation and real-time PCR assay. Results: Compared to sham mice, BCAS in mice significantly induced cerebral hypoperfusion and cognitive dysfunction, increased cardiac hypertrophy, as indicated by the increased heart weight and the ratio of heart weight/body weight, and induced cardiac dysfunction and left ventricular (LV) enlargement, indicated by a decreased LV ejection fraction (LVEF) and LV fractional shortening (LVFS), increased LV dimension (LVD), and increased LV mass. Cognitive deficits significantly correlated with cardiac deficits. BCAS mice also exhibited significantly increased cardiac fibrosis, increased oxidative stress, as indicated by 4-hydroxynonenal and NADPH oxidase-2, increased leukocyte and macrophage infiltration into the heart, and increased cardiac interleukin-6 and thrombin gene expression. Conclusions: BCAS in mice without primary cardiac disease provokes cardiac dysfunction, which, in part, may be mediated by increased inflammation and oxidative stress.

G-MDSCs promote aging-related cardiac fibrosis by activating myofibroblasts and preventing senescence

Aging is one of the most prominent risk factors for heart failure. Myeloid-derived suppressor cells (MDSCs) accumulate in aged tissue and have been confirmed to be associated with various aging-related diseases. However, the role of MDSCs in the aging heart remains unknown. Through RNA-seq and biochemical approaches, we found that granulocytic MDSCs (G-MDSCs) accumulated significantly in the aging heart compared with monocytic MDSCs (M-MDSCs). Therefore, we explored the effects of G-MDSCs on the aging heart. We found that the adoptive transfer of G-MDSCs of aging mice to young hearts resulted in cardiac diastolic dysfunction by inducing cardiac fibrosis, similar to that in aging hearts. S100A8/A9 derived from G-MDSCs induced inflammatory phenotypes and increased the osteopontin (OPN) level in fibroblasts. The upregulation of fibroblast growth factor 2 (FGF2) expression in fibroblasts mediated by G-MDSCs promoted antisenescence and antiapoptotic phenotypes of fibroblasts. SOX9 is the downstream gene of FGF2 and is required for FGF2-mediated and G-MDSC-mediated profibrotic effects. Interestingly, both FGF2 levels and SOX9 levels were upregulated in fibroblasts but not in G-MDSCs and were independent of S100A8/9. Therefore, a novel FGF2-SOX9 signaling axis that regulates fibroblast self-renewal and antiapoptotic phenotypes was identified. Our study revealed the mechanism by which G-MDSCs promote cardiac fibrosis via the secretion of S100A8/A9 and the regulation of FGF2-SOX9 signaling in fibroblasts during aging.

The Role of HECT-Type E3 Ligase in the Development of Cardiac Disease

Despite advances in medicine, cardiac disease remains an increasing health problem associated with a high mortality rate. Maladaptive cardiac remodeling, such as cardiac hypertrophy and fibrosis, is a risk factor for heart failure; therefore, it is critical to identify new therapeutic targets. Failing heart is reported to be associated with hyper-ubiquitylation and impairment of the ubiquitin–proteasome system, indicating an importance of ubiquitylation in the development of cardiac disease. Ubiquitylation is a post-translational modification that plays a pivotal role in protein function and degradation. In 1995, homologous to E6AP C-terminus (HECT) type E3 ligases were discovered. E3 ligases are key enzymes in ubiquitylation and are classified into three families: really interesting new genes (RING), HECT, and RING-between-RINGs (RBRs). Moreover, 28 HECT-type E3 ligases have been identified in human beings. It is well conserved in evolution and is characterized by the direct attachment of ubiquitin to substrates. HECT-type E3 ligase is reported to be involved in a wide range of human diseases and health. The role of HECT-type E3 ligases in the development of cardiac diseases has been uncovered in the last decade. There are only a few review articles summarizing recent advancements regarding HECT-type E3 ligase in the field of cardiac disease. This study focused on cardiac remodeling and described the role of HECT-type E3 ligases in the development of cardiac disease. Moreover, this study revealed that the current knowledge could be exploited for the development of new clinical therapies.

The association between RGS4 and choline in cardiac fibrosis

Background

Myocardial fibrosis is caused by the adverse and powerful remodeling of the heart secondary to the death of cardiomyocytes after myocardial infarction. Regulators of G protein Signaling (RGS) 4 is involved in cardiac diseases through regulating G protein-coupled receptors (GPCRs).

Methods

Cardiac fibrosis models were established through cardiac fibroblasts (CFs) treatment with transforming growth factor (TGF)-β1 in vitro and mice subjected to myocardial infarction in vivo. The mRNA expression of RGS4, collagen I/III and α-SMA detected by qRT-PCR. Protein level of RGS4, collagen I, CTGF and α-SMA detected by Western blot. The ejection fraction (EF%) and fractional shortening (FS%) of mice were measured by echocardiography. Collagen deposition of mice was tested by Masson staining.

Results

The expression of RGS4 increased in CFs treatment with TGF-β1 and in MI mice. The model of cardiac fibrosis detected by qRT-PCR and Western blot. It was demonstrated that inhibition of RGS4 expression improved cardiac fibrosis by transfection with small interfering RNA in CFs and injection with lentivirus shRNA in mice. The protective effect of choline against cardiac fibrosis was counteracted by overexpression of RGS4 in vitro and in vivo. Moreover, choline inhibited the protein level of TGF-β1, p-Smad2/3, p-p38 and p-ERK1/2 in CFs treated with TGF-β1, which were restored by RGS4 overexpression.

Conclusion

This study demonstrated that RGS4 promoted cardiac fibrosis and attenuated the anti-cardiac fibrosis of choline. RGS4 may weaken anti-cardiac fibrosis of choline through TGF-β1/Smad and MAPK signaling pathways.

Therapeutic Targeting of Interleukin-11 Signalling Reduces Pressure Overload-Induced Cardiac Fibrosis in Mice

There are currently no specific treatments for cardiac fibrosis. We tested the efficacy of a neutralising anti-IL11 antibody (X203) to reduce cardiac fibrosis in two preclinical models: transverse aortic constriction (TAC) and chronic angiotensin II infusion (AngII). In the first model, male C57BL/6J mice were subjected to TAC for 2 weeks. In the second model, mice received continuous angiotensin II for 4 weeks via subcutaneous pump. In both models, mice received either 20 mg/kg of X203 or isotype-control antibody twice-weekly, starting 24 h after surgery. Cardiac fibrosis and extracellular matrix gene expression were assessed by RT-qPCR, Western blot, histology and collagen (hydroxyproline) assays. In both models, X203 significantly reduced pro-fibrotic gene expression and myocardial fibrosis (TAC: 51% reduction in total collagen, P < 0.001, 39% in perivascular fibrosis, P < 0.001; AngII: 17% reduction in total collagen, P = 0.04, 83% in perivascular fibrosis, P < 0.001). Pharmacological targeting of IL11 reduces cardiac fibrosis in preclinical models. Figa Graphical Abstract.

Melatonin to Rescue the Aged Heart: Antiarrhythmic and Antioxidant Benefits

Aging comes with gradual loss of functions that increase the vulnerability to disease, senescence, and death. The mechanisms underlying these processes are linked to a prolonged imbalance between damage and repair. Damaging mechanisms include oxidative stress, mitochondrial dysfunction, chronodisruption, inflammation, and telomere attrition, as well as genetic and epigenetic alterations. Several endogenous tissue repairing mechanisms also decrease. These alterations associated with aging affect the entire organism. The most devastating manifestations involve the cardiovascular system and may lead to lethal cardiac arrhythmias. Together with structural remodeling, electrophysiological and intercellular communication alterations during aging predispose to arrhythmic events. Despite the knowledge on repairing mechanisms in the cardiovascular system, effective antiaging strategies able to reduce the risk of arrhythmias are still missing. Melatonin is a promising therapeutic candidate due to its pleiotropic actions. This indoleamine regulates chronobiology and endocrine physiology. Of relevance, melatonin is an antiaging, antioxidant, antiapoptotic, antiarrhythmic, immunomodulatory, and antiproliferative molecule. This review focuses on the protective effects of melatonin on age-induced cardiac functional and structural alterations, potentially becoming a new fountain of youth for the heart.

Role of FoxO transcription factors in aging-associated cardiovascular diseases

Aging constitutes a major risk factor toward the development of cardiovascular diseases (CVDs). The aging heart undergoes several changes at the molecular, cellular and physiological levels, which diminishes its contractile function and weakens stress tolerance. Further, old age increases the exposure to risk factors such as hypertension, diabetes and hypercholesterolemia. Notably, research in the past decades have identified FoxO subfamily of the forkhead transcription factors as key players in regulating diverse cellular processes linked to cardiac aging and diseases. In the present chapter, we discuss the important role of FoxO in the development of various aging-associated cardiovascular complications such as cardiac hypertrophy, cardiac fibrosis, heart failure, vascular dysfunction, atherosclerosis, hypertension and myocardial ischemia. Besides, we will also discuss the role of FoxO in cardiometabolic alterations, autophagy and proteasomal degradation, which are implicated in aging-associated cardiac dysfunction.

Healthy Aging Biomarkers: The INSPIRE's Contribution

The find solutions for optimizing healthy aging and increase health span is one of the main challenges for our society. A novel healthcare model based on integration and a shift on research and care towards the maintenance of optimal functional levels are now seen as priorities by the WHO. To address this issue, an integrative global strategy mixing longitudinal and experimental cohorts with an innovative transverse understanding of physiological functioning is missing. While the current approach to the biology of aging is mainly focused on parenchymal cells, we propose that age-related loss of function is largely determined by three elements which constitute the general ground supporting the different specific parenchyma: i.e. the stroma, the immune system and metabolism. Such strategy that is implemented in INSPIRE projects can strongly help to find a composite biomarker capable of predicting changes in capacity across the life course with thresholds signalling frailty and care dependence.

D-galactose-induced toxicity associated senescence mitigated by alpinate oxyphyllae fructus fortified adipose-derived mesenchymal stem cells

This study addresses the effect of D-galactose-induced toxicity associated senescence mitigated by alpinate oxyphyllae fructus (AOF; Alpinia oxyphylla Miq) extracts fortified with adipose-derived mesenchymal stem cells (ADMSCs) in rats. Male 18 week-old Wistar Kyoto (WKY) rats were used in this study. We analyzed cardiac fibrosis by Masson's trichrome staining. The tissue sections were dyed using hematoxylin and eosin (H&E). Tissue sections were stained for the restoration of Nrf2 expression in treatment groups by immunohistochemistry. Immunohistochemistry and western blotting analysis showed that AOF with ADMSCs could significantly reduce aging-induced oxidative stress in D-galactose-induced aging rat hearts by inducing Nrf2 pathway. Reduction in ROS resulted in the suppression of inflammatory signals (p-NF-κB and IL-6). Histopathological studies were showed an increased interstitium and collagen accumulation in aging-induced heart sections. However, AOF and ADMSCs treated hearts were recovered from cardiac remodeling. Furthermore, hypertrophy and fibrosis associated markers were also significantly reduced (P < .05) in treatment groups. We speculate that ADMSCs might activate certain paracrine factors, which could target the upstream activator of aging associated cardiac complications and AOF might provide homing for these stem cells.

Calcium mediated functional interplay between myocardial cells upon laser-induced single-cell injury: an in vitro study of cardiac cell death signaling mechanisms

Background

The electromechanical function of myocardial tissue depends on the intercellular communication between cardiomyocytes (CMs) as well as their crosstalk with other cell types. Cell injury, and subsequent death trigger inflammation as in myocardial infarction (MI) resulting in myocardial remodeling. Although mechanisms underlying myocardial cell death have been studied so far, the signaling events following single cell death and spontaneous response of connected cells in the myocardial tissue is still barely understood.

Methods

Here, we investigated the effect of laser-induced single cell death on Calcium (Ca²⁺) concentrations and transport in myocardial cell clusters in vitro. Spatial and temporal changes in intracellular Ca²⁺ concentrations [Ca²⁺]_i were studied using a fluorescent calcium indicator, Fluo-4AM. Spontaneous signaling events following cell death were studied in rat embryonic cardiomyocytes and non-myocytes using separate cell culture systems.

Results

Cell death triggered spontaneous increase in intracellular Ca²⁺ levels ([Ca²⁺]_i) of surrounding cells. The spread of the observed propagating Ca²⁺ signal was slow and sustained in myocytes while it was rapid and transient in fibroblasts (Fbs). Further, sustained high Ca²⁺ levels temporarily impaired the contractility in CMs. The cell-type specific effect of ablation was confirmed using separate cultures of CMs and Fbs. Comparing Ca²⁺ propagation speed in myocytes and fibroblasts, we argue for a diffusion-driven Ca²⁺ propagation in myocytes, but not in fibroblasts. Radial and sequential Ca²⁺ diffusion across the CMs through cell–cell contacts and presence of Cx43-based intercellular junctions indicated a gap junction flow of Ca²⁺.

Conclusions

These findings illustrate the spontaneous Ca²⁺-mediated functional interplay in myocardial cell clusters upon mechanical injury and, further, the difference in Ca²⁺ signaling in cardiomyocytes and fibroblasts.

Video Abstract

Clinical factors associated with the intraventricular conduction disturbances in Swiss middle-aged adults: The CoLaus|PsyCoLaus study

BACKGROUND

Intraventricular conduction disturbances are associated with an increased risk of adverse cardiovascular outcomes. However, data about factors associated with intraventricular conduction disturbances are sparse. We aimed to identify the clinical factors associated with intraventricular conduction disturbances in the general population.

METHODS

Cross-sectional study in a sample of 3704 participants (age range 45-86 years, 55.2% women). Intraventricular conduction disturbances were defined as QRS > 110 ms on electrocardiograms, and classified into right bundle branch block (RBBB), left bundle branch block (LBBB), left anterior fascicular block (LAFB) and non-specific intraventricular conduction disturbances (NIVCD).

RESULTS

The number of participants, the resulting prevalence (square brackets) and 95% CI (round brackets) of intraventricular conduction disturbances and subtypes (RBBB, LBBB, LAFB and NIVCD) were 187 [5.1% (4.4-5.8%)], 103 [2.9%, (2.3-3.4%)], 29 [0.8% (0.6-1.1%)], 31 (0.9% [0.6-1.2%]), and 47 [1.3% (0.9-1.7)], respectively. Multivariable logistic regression identified male sex [odds ratio and (95% CI): 2.55 (1.34-4.86)] and increasing age (p-value for trend <0.001) as being associated with RBBB; hypertension [3.08 (1.20-7.91)] and elevated NT-proBNP [3.26 (1.43-7.41)] as being associated with LBBB; elevated NT-proBNP [3.14 (1.32-7.46)] as being associated with LFAB; and male sex [5.97 (1.91-18.7)] and increased height [1.31 (1.06-1.63)] as being associated with NIVCD.

CONCLUSION

In a sample of the Swiss middle-aged population, the clinical factors associated with intraventricular conduction disturbances differed according to the intraventricular conduction disturbances subtype: male sex and ageing for RBBB; hypertension and elevated NT-proBNP for LBBB; elevated NT-proBNP for LAFB; and male sex and increased height for NIVCD.

Cadherin-11 and cardiac fibrosis: A common target for a common pathology

Cardiac fibrosis represents an enormous health concern as it is prevalent in nearly every form of cardiovascular disease, the leading cause of death worldwide. Fibrosis is characterized by the activation of fibroblasts into myofibroblasts, a contractile cell type that secretes significant amounts of extracellular matrix components; however, the onset of this condition is also due to persistent inflammation and the cellular responses to a changing mechanical environment. In this review, we provide an overview of the pro-fibrotic, pro-inflammatory, and biomechanical mechanisms that lead to cardiac fibrosis in cardiovascular diseases. We then discuss cadherin-11, an intercellular adhesion protein present on both myofibroblasts and inflammatory cells, as a potential link for all three of the fibrotic mechanisms. Since experimentally blocking cadherin-11 dimerization prevents fibrotic diseases including cardiac fibrosis, understanding how this protein can be targeted for therapeutic use could lead to better treatments for patients with heart disease.

Regulation of cellular senescence by extracellular matrix during chronic fibrotic diseases

The extracellular matrix (ECM) is a complex network of macromolecules surrounding cells providing structural support and stability to tissues. The understanding of the ECM and the diverse roles it plays in development, homoeostasis and injury have greatly advanced in the last three decades. The ECM is crucial for maintaining tissue homoeostasis but also many pathological conditions arise from aberrant matrix remodelling during ageing. Ageing is characterised as functional decline of tissue over time ultimately leading to tissue dysfunction, and is a risk factor in many diseases including cardiovascular disease, diabetes, cancer, dementia, glaucoma, chronic obstructive pulmonary disease (COPD) and fibrosis. ECM changes are recognised as a major driver of aberrant cell responses. Mesenchymal cells in aged tissue show signs of growth arrest and resistance to apoptosis, which are indicative of cellular senescence. It was recently postulated that cellular senescence contributes to the pathogenesis of chronic fibrotic diseases in the heart, kidney, liver and lung. Senescent cells negatively impact tissue regeneration while creating a pro-inflammatory environment as part of the senescence-associated secretory phenotype (SASP) favouring disease progression. In this review, we explore and summarise the current knowledge around how aberrant ECM potentially influences the senescent phenotype in chronic fibrotic diseases. Lastly, we will explore the possibility for interventions in the ECM-senescence regulatory pathways for therapeutic potential in chronic fibrotic diseases.

Role of Exercise on Alleviating Pressure Overload-Induced Left Ventricular Dysfunction and Remodeling via AMPK-Dependent Autophagy Activation

Cardiac hypertrophy is one of the significant risk factors that result in maladaptive cardiac remodeling and heart failure, and exercise is known to exert cardioprotection. In this research, the cardioprotective function and exercise mechanisms were explored.The rats underwent transverse aortic constriction (TAC) or a sham operation. The rats that received TAC were randomly assigned to five groups: (1) rats subjected to a sham operation as control group (SC), (2) rats that underwent TAC group (TC), (3) TAC and moderate-intensity exercise group (TE), (4) TE plus 3-MA group (TEM), and (5) TE plus Compound C group (TEC). The heart function was measured via echocardiography. Histological analysis and relative protein testing were conducted to analyze collagen deposition and apoptosis. Furthermore, western blot was employed to measure the protein expression of relevant signaling pathways. Impaired cardiac function, interstitial fibrosis, enhanced apoptosis, and ER stress were observed in the TAC-induced left ventricular hypertrophy. Exercise attenuated TAC-induced cardiac dysfunction, interstitial fibrosis, and ER stress-related apoptosis. In addition, exercise significantly improved autophagy and upregulated AMPK phosphorylation. Furthermore, AMPK inhibitor Compound C repressed the activation of AMPK, and autophagy inhibitor 3-methyladenine reversed exercise-induced autophagy. All of these abolished the protection of exercise against cardiac dysfunction and fibrosis induced by TAC.Our results indicated that 4 weeks of treadmill exercise could alleviate pressure overload-induced LV dysfunction and remodeling via an autophagy-dependent mechanism, which was induced by enhancing autophagy through the activation of AMPK.

Bioorthogonal click chemistries enable simultaneous spatial patterning of multiple proteins to probe synergistic protein effects on fibroblast function

Three biorthogonal click reactions, a photoinitiated thiol-yne reaction, an azide-alkyne cycloaddition, and a methyltetrazine-transcyclooctene Diels Alder, were used to independently control the presentation of several bioactive proteins to valvular interstitial cells (VICs) in hydrogel scaffolds. Tethered fibroblast growth factor (FGF-2) was found to suppress myofibroblast activation (from 48 ± 7% to 17 ± 6%) and promote proliferation (from 10 ± 2% to 54 ± 3%) at a concentration of 10 ng/mL. In the presence of the pro-fibrotic cytokine transforming growth factor-beta (TGF-β1), FGF-2 could protect the VIC fibroblast phenotype, even at much higher concentrations of TGF-β1 than that of FGF-2. With respect to the fibrocalcific VIC phenotype, TGF-β1 and bone-morphogenic protein-2 (BMP-2) were found to synergistically promote calcific nodule formation (a five-fold increase in nodules compared to TGF-β1 or BMP-2 alone). Exploiting the orthogonal click reactions, FGF-2, TGF-β1 and BMP-2 combinations were patterned into distinct regions on a hydrogel to control VIC activation and nodule formation. Cellular crosstalk between separate regions of the same scaffold was affected by the size of each region as well as the interfacial area between different regions. Collectively, these results demonstrate the versatility and robustness of a photoinitiated thiol-yne reaction to template pendant functionalities that allow for the bioconjugation of multiple proteins. This approach maintains protein bioactivity, providing an in vitro platform capable of achieving a better understanding of the complex mechanisms involved in tissue fibrosis.

Osteopontin: The Molecular Bridge between Fat and Cardiac-Renal Disorders

Osteopontin (OPN) is a multifaceted matricellular protein, with well-recognized roles in both the physiological and pathological processes in the body. OPN is expressed in the main organs and cell types, in which it induces different biological actions. During physiological conditioning, OPN acts as both an intracellular protein and soluble excreted cytokine, regulating tissue remodeling and immune-infiltrate in adipose tissue the heart and the kidney. In contrast, the increased expression of OPN has been correlated with the severity of the cardiovascular and renal outcomes associated with obesity. Indeed, OPN expression is at the “cross roads” of visceral fat extension, cardiovascular diseases (CVDs) and renal disorders, in which OPN orchestrates the molecular interactions, leading to chronic low-grade inflammation. The common factor associated with OPN overexpression in adipose, cardiac and renal tissues seems attributable to the concomitant increase in visceral fat size and the increase in infiltrated OPN⁺ macrophages. This review underlines the current knowledge on the molecular interactions between obesity and the cardiac–renal disorders ruled by OPN.

Danon Disease-Associated LAMP-2 Deficiency Drives Metabolic Signature Indicative of Mitochondrial Aging and Fibrosis in Cardiac Tissue and hiPSC-Derived Cardiomyocytes

Danon disease is a severe X-linked disorder caused by deficiency of the lysosome-associated membrane protein-2 (LAMP-2). Clinical manifestations are phenotypically diverse and consist of hypertrophic and dilated cardiomyopathies, skeletal myopathy, retinopathy, and intellectual dysfunction. Here, we investigated the metabolic landscape of Danon disease by applying a multi-omics approach and combined structural and functional readouts provided by Raman and atomic force microscopy. Using these tools, Danon patient-derived cardiac tissue, primary fibroblasts, and human induced pluripotent stem cells differentiated into cardiomyocytes (hiPSC-CMs) were analyzed. Metabolic profiling indicated LAMP-2 deficiency promoted a switch toward glycolysis accompanied by rerouting of tryptophan metabolism. Cardiomyocytes' energetic balance and NAD+/NADH ratio appeared to be maintained despite mitochondrial aging. In turn, metabolic adaption was accompanied by a senescence-associated signature. Similarly, Danon fibroblasts appeared more stress prone and less biomechanically compliant. Overall, shaping of both morphology and metabolism contributed to the loss of cardiac biomechanical competence that characterizes the clinical progression of Danon disease.

Sex Differences in Progression of Diabetic Cardiomyopathy in OVE26 Type 1 Diabetic Mice

OVE26 mice are a widely used transgenic model of early-onset type 1 diabetes. These mice overexpress calmodulin in their pancreatic β cells, develop severe diabetes within the first weeks of life, and progress to severe diabetic complications including diabetic nephropathy and diabetic cardiomyopathy (DCM). To date, diabetic nephropathy in OVE26 mice has been well explored, leaving the progression of DCM and the gender impact in this type 1 diabetes model still unrevealed. In our study, male and female OVE26 mice and age-matched nondiabetic FVB mice were examined at 4, 12, 24, and 36 weeks for their cardiac function, body weight, blood glucose, and heart weight/tibia length ratio. Further, histopathological examination and Western blot analysis for the key markers demonstrate that DCM appears at 24 weeks OVE26 mice, initiating with cardiac senescence, followed by fibrosis and then cardiac dysfunction. Mitochondrial respiration function analysis showed no indication of dysfunction in OVE26 mice at 24 weeks of age in both genders. In addition, no significant difference for the pathogenic progression was observed between OVE26 and FVB mice in both males and females. In conclusion, this study suggests cardiac senescence and fibrosis, which may be amended by sex differences, play key roles in the progression of DCM in OVE26 mice. The comprehensive characterization of diabetic cardiomyopathy progression and the sex difference impact in OVE26 mice provides a basis for future study on DCM using OVE26 mice.

Clinical determinants of the PR interval duration in Swiss middle-aged adults: The CoLaus/PsyCoLaus study

Background

Prolonged PR interval (PRi) is associated with adverse outcomes. However, PRi determinants are poorly known. We aimed to identify the clinical determinants of the PRi duration in the general population.

Hypothesis

Some clinical data are associated with prolonged PRi.

Methods

Cross‐sectional study conducted between 2014 and 2017. Electrocardiogram‐derived PRi duration was categorized into normal or prolonged (>200 ms). Determinants were identified using stepwise logistic regression, and results were expressed as multivariable‐adjusted odds ratio (OR) (95% confidence interval). A further analysis was performed adjusting for antiarrhythmic drugs, P‐wave contribution to PRi duration, electrolytes (kalemia, calcemia, and magnesemia), and history of cardiovascular disease.

Results

Overall, 3655 participants with measurable PRi duration were included (55.6% females; mean age 62 ± 10 years), and 330 (9.0%) had prolonged PRi. Stepwise logistic regression identified male sex (OR 1.41 [1.02‐1.97]); aging (65‐74 years: OR 2.29 [1.61‐3.24], and ≥ 75 years: OR 4.21 [2.81‐6.31]); increased height (per 5 cm, OR 1.15 [1.06‐1.25]); hypertension (OR 1.37 [1.06‐1.77]); and hs troponin T (OR 1.67 [1.15‐2.43]) as significantly and positively associated, and high resting heart rate (≥70 beats/min, OR 0.43 [0.29‐0.62]) as negatively associated with prolonged PRi. After further adjustment, male sex, aging and increased height remained positively, and high resting heart rate negatively associated with prolonged PRi. Hypertension and hs troponin T were no longer associated.

Conclusion

In a sample of the Swiss middle‐aged population, male sex, aging and increased height significantly increased the likelihood of a prolonged PRi duration, whereas a high resting heart rate decreased it.

Leukocyte-Dependent Regulation of Cardiac Fibrosis

Cardiac fibrosis begins as an intrinsic response to injury or ageing that functions to preserve the tissue from further damage. Fibrosis results from activated cardiac myofibroblasts, which secrete extracellular matrix (ECM) proteins in an effort to replace damaged tissue; however, excessive ECM deposition leads to pathological fibrotic remodeling. At this extent, fibrosis gravely disturbs myocardial compliance, and ultimately leads to adverse outcomes like heart failure with heightened mortality. As such, understanding the complexity behind fibrotic remodeling has been a focal point of cardiac research in recent years. Resident cardiac fibroblasts and activated myofibroblasts have been proven integral to the fibrotic response; however, several findings point to additional cell types that may contribute to the development of pathological fibrosis. For one, leukocytes expand in number after injury and exhibit high plasticity, thus their distinct role(s) in cardiac fibrosis is an ongoing and controversial field of study. This review summarizes current findings, focusing on both direct and indirect leukocyte-mediated mechanisms of fibrosis, which may provide novel targeted strategies against fibrotic remodeling.

IL-11 in cardiac and renal fibrosis: Late to the party but a central player

Fibrosis is a pathophysiological hallmark of cardiorenal disease. In the heart, fibrosis leads to contractile dysfunction and arrhythmias; in the kidney, it is the final common pathway for many diseases and predicts end-stage renal failure. Despite this, there are currently no specific anti-fibrotic treatments available for cardiac or renal disease. Recently and unexpectedly, IL-11 was found to be of major importance for cardiorenal fibroblast activation and fibrosis. In mouse models, IL-11 overexpression caused fibrosis of the heart and kidney while genetic deletion of Il11ra1 protected against fibrosis and preserved organ function. Neutralizing antibodies against IL-11 or IL-11RA have been developed that have anti-fibrotic activity in human fibroblasts and protect against fibrosis in murine models of disease. While IL-11 biology has been little studied and, we suggest, largely misunderstood, its autocrine activity in myofibroblasts appears non-redundant for fibrosis, which offers new opportunities to better understand and potentially target cardiorenal fibrosis.

Effects of aging and exercise training on mitochondrial function and apoptosis in the rat heart

Aging is associated with vulnerability to cardiovascular diseases, and mitochondrial dysfunction plays a critical role in cardiovascular disease pathogenesis. Exercise training is associated with benefits against chronic cardiac diseases. The purpose of this study was to determine the effects of aging and treadmill exercise training on mitochondrial function and apoptosis in the rat heart. Fischer 344 rats were divided into young sedentary (YS; n = 10, 4 months), young exercise (YE; n = 10, 4 months), old sedentary (OS; n = 10, 20 months), and old exercise (OE; n = 10, 20 months) groups. Exercise training groups ran on a treadmill at 15 m/min (young) or 10 m/min (old), 45 min/day, 5 days/week for 8 weeks. Morphological parameters, mitochondrial function, mitochondrial dynamics, mitophagy, and mitochondria-mediated apoptosis were analyzed in cardiac muscle. Mitochondrial O₂ respiratory capacity and Ca²⁺ retention capacity gradually decreased, and mitochondrial H₂O₂ emitting potential significantly increased with aging. Exercise training attenuated aging-induced mitochondrial H₂O₂ emitting potential and mitochondrial O₂ respiratory capacity, while protecting Ca²⁺ retention in the old groups. Aging triggered imbalanced mitochondrial dynamics and excess mitophagy, while exercise training ameliorated the aging-induced imbalance in mitochondrial dynamics and excess mitophagy. Aging induced increase in Bax and cleaved caspase-3 protein levels, while decreasing Bcl-2 levels. Exercise training protected against the elevation of apoptotic signaling markers by decreasing Bax and cleaved caspase-3 and increasing Bcl-2 protein levels, while decreasing the Bax/Bcl-2 ratio and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive myonuclei. These data demonstrate that regular exercise training prevents aging-induced impairment of mitochondrial function and mitochondria-mediated apoptosis in cardiac muscles.

Idiopathic Myocardial Fibrosis in Captive Chimpanzees (Pan troglodytes)

Cardiovascular disorders and predominantly idiopathic myocardial fibrosis are frequently associated with mortality among zoo-housed chimpanzees (Pan troglodytes). Formalin-fixed whole hearts of deceased chimpanzees housed in zoos (n = 33) and an African sanctuary (n = 2) underwent detailed macroscopic and histopathologic examination using a standardized protocol. Archived histological slides from the hearts of 23 additional African sanctuary-housed chimpanzees were also examined. Myocardial fibrosis (MF) was identified in 30 of 33 (91%) of the zoo-housed chimpanzees but none of the 25 sanctuary-housed chimpanzees. MF was shown to be characterized by both interstitial and replacement fibrosis. Immunophenotyping demonstrated that the fibrotic lesions were accompanied by the increased presence of macrophages, alpha smooth muscle actin-positive myofibroblasts, and a minimal to mild T-cell-dominant leukocyte infiltration. There was no convincing evidence of cardiotropic viral infection or suggestion that diabetes mellitus or vitamin E or selenium deficiency were associated with the presence of the lesion. However, serum vitamin D concentrations among zoo-housed chimpanzees were found to be lower in seasons of low ultraviolet light levels.

As time flies by: Investigating cardiac aging in the short-lived Drosophila model

Aging is associated with a decline in heart function across the tissue, cellular, and molecular levels. The risk of cardiovascular disease grows significantly over time, and as developed countries continue to see an increase in lifespan, the cost of cardiovascular healthcare for the elderly will undoubtedly rise. The molecular basis for cardiac function deterioration with age is multifaceted and not entirely clear, and there is a limit to what investigations can be performed on human subjects or mammalian models. Drosophila melanogaster has emerged as a useful model organism for studying aging in a short timeframe, benefitting from a suite of molecular and genetic tools and displaying highly conserved traits of cardiac senescence. Here, we discuss recent advances in our understanding of cardiac aging and how the fruit fly has aided in these developments.

Aging mechanisms and intervention targets

Premature aging occurs frequently to various tissues and organs resulting in the tissue-specific chronic diseases. The mechanisms of tissue-specific premature aging are largely unknown. In response to environmental cues, aging may originate from cytoplasm or the nucleus of a cell with cytoplasm aging in association with organelle degeneration in terminally differentiated cells and nuclear aging with dysfunctional telomeres and irreversible cell cycle arrest in stem and cancer cells. Either cytoplasm aging or nuclear aging may cause extracellular senescence-associated low-grade inflammation to spread aging. Referring to the recent findings in this special issue of Healthy Aging in CEPP and beyond, we describe the molecular and cellular mechanisms of physiological aging and tissue-specific pathological aging in chronic diseases.