Activin type II receptor signaling in cardiac aging and heart failure

Controversies and Conundrums in Cardiac Cachexia: Key Questions About Wasting in Patients With HFrEF

Cardiac cachexia is characterized by unintentional catabolic weight loss, decreased appetite, and inflammation and is common in patients with stage D (advanced) heart failure with reduced ejection fraction (HFrEF). Cardiac cachexia and related muscle-wasting syndromes are markers of, and a consequence of, the heart failure (HF) syndrome. Although many potential modalities for identifying cardiac cachexia exist, the optimal definition, diagnostic tools, and treatment options for cardiac cachexia remain unclear. Furthermore, it remains unclear whether attempts to reverse muscle wasting prior to advanced HF surgeries, such as left ventricular assist devices and heart transplantation, can improve outcomes. It is important that HF clinicians and dietitians are aware of the pathophysiology and mechanisms of muscle-wasting syndromes in patients with HF, to aid in the recognition and risk stratification of advanced HFrEF. Although the opportunities and rationale for attempting to address cardiac cachexia prior to advanced HF surgeries are uncertain, recent publications suggest that control of the neurohumoral syndrome of advanced HF may be important to permit the recovery of skeletal muscle mass.

Proteomic signatures of healthy dietary patterns are associated with lower risks of major chronic diseases and mortality

Healthy dietary patterns have been linked to a decreased risk of chronic diseases. However, it remains uncertain whether proteomic signatures can reflect proteome response to healthy diet patterns, and whether these proteomic signatures are associated with health outcomes. Using data from the UK Biobank including Olink plasma proteins, we identified substantial proteomic variation in relation to adherence to eight healthy dietary patterns. The proteomic signatures, reflecting adherence and proteome response to healthy dietary patterns, were prospectively associated with lower risks of diabetes, cardiovascular diseases, chronic respiratory diseases, chronic kidney diseases and cancers, along with longer life expectancy, even after adjusting for corresponding dietary patterns. These findings suggest proteomic signatures have the potential to complement traditional dietary assessments and deepen our understanding of the relationships between dietary patterns and chronic diseases.

The onset and the development of cardiometabolic aging: an insight into the underlying mechanisms

Metabolic compromise is crucial in aggravating age-associated chronic inflammation, oxidative stress, mitochondrial damage, increased LDL and triglycerides, and elevated blood pressure. Excessive adiposity, hyperglycemia, and insulin resistance due to aging are associated with elevated levels of damaging free radicals, inducing a proinflammatory state and hampering immune cell activity, leading to a malfunctioning cardiometabolic condition. The age-associated oxidative load and redox imbalance are contributing factors for cardiometabolic morbidities via vascular remodelling and endothelial damage. Recent evidence has claimed the importance of gut microbiota in maintaining regular metabolic activity, which declines with chronological aging and cardiometabolic comorbidities. Genetic mutations, polymorphic changes, and environmental factors strongly correlate with increased vulnerability to aberrant cardiometabolic changes by affecting key physiological pathways. Numerous studies have reported a robust link between biological aging and cardiometabolic dysfunction. This review outlines the scientific evidence exploring potential mechanisms behind the onset and development of cardiovascular and metabolic issues, particularly exacerbated with aging.

Novel insights into the pleiotropic health effects of growth differentiation factor 11 gained from genome-wide association studies in population biobanks

BACKGROUND

Growth differentiation factor 11 (GDF11) is a member of the transforming growth factor-β (TGF-β) superfamily that has gained considerable attention over the last decade for its observed ability to reverse age-related deterioration of multiple tissues, including the heart. Yet as many researchers have struggled to confirm the cardioprotective and anti-aging effects of GDF11, the topic has grown increasingly controversial, and the field has reached an impasse. We postulated that a clearer understanding of GDF11 could be gained by investigating its health effects at the population level.

METHODS AND RESULTS

We employed a comprehensive strategy to interrogate results from genome-wide association studies in population Biobanks. Interestingly, phenome-wide association studies (PheWAS) of GDF11 tissue-specific cis-eQTLs revealed associations with asthma, immune function, lung function, and thyroid phenotypes. Furthermore, PheWAS of GDF11 genetic variants confirmed these results, revealing similar associations with asthma, immune function, lung function, and thyroid health. To complement these findings, we mined results from transcriptome-wide association studies, which uncovered associations between predicted tissue-specific GDF11 expression and the same health effects identified from PheWAS analyses.

CONCLUSIONS

In this study, we report novel relationships between GDF11 and disease, namely asthma and hypothyroidism, in contrast to its formerly assumed role as a rejuvenating factor in basic aging and cardiovascular health. We propose that these associations are mediated through the involvement of GDF11 in inflammatory signaling pathways. Taken together, these findings provide new insights into the health effects of GDF11 at the population level and warrant future studies investigating the role of GDF11 in these specific health conditions.

Systemic aging fuels heart failure: Molecular mechanisms and therapeutic avenues

Systemic aging influences various physiological processes and contributes to structural and functional decline in cardiac tissue. These alterations include an increased incidence of left ventricular hypertrophy, a decline in left ventricular diastolic function, left atrial dilation, atrial fibrillation, myocardial fibrosis and cardiac amyloidosis, elevating susceptibility to chronic heart failure (HF) in the elderly. Age-related cardiac dysfunction stems from prolonged exposure to genomic, epigenetic, oxidative, autophagic, inflammatory and regenerative stresses, along with the accumulation of senescent cells. Concurrently, age-related structural and functional changes in the vascular system, attributed to endothelial dysfunction, arterial stiffness, impaired angiogenesis, oxidative stress and inflammation, impose additional strain on the heart. Dysregulated mechanosignalling and impaired nitric oxide signalling play critical roles in the age-related vascular dysfunction associated with HF. Metabolic aging drives intricate shifts in glucose and lipid metabolism, leading to insulin resistance, mitochondrial dysfunction and lipid accumulation within cardiomyocytes. These alterations contribute to cardiac hypertrophy, fibrosis and impaired contractility, ultimately propelling HF. Systemic low-grade chronic inflammation, in conjunction with the senescence-associated secretory phenotype, aggravates cardiac dysfunction with age by promoting immune cell infiltration into the myocardium, fostering HF. This is further exacerbated by age-related comorbidities like coronary artery disease (CAD), atherosclerosis, hypertension, obesity, diabetes and chronic kidney disease (CKD). CAD and atherosclerosis induce myocardial ischaemia and adverse remodelling, while hypertension contributes to cardiac hypertrophy and fibrosis. Obesity-associated insulin resistance, inflammation and dyslipidaemia create a profibrotic cardiac environment, whereas diabetes-related metabolic disturbances further impair cardiac function. CKD-related fluid overload, electrolyte imbalances and uraemic toxins exacerbate HF through systemic inflammation and neurohormonal renin-angiotensin-aldosterone system (RAAS) activation. Recognizing aging as a modifiable process has opened avenues to target systemic aging in HF through both lifestyle interventions and therapeutics. Exercise, known for its antioxidant effects, can partly reverse pathological cardiac remodelling in the elderly by countering processes linked to age-related chronic HF, such as mitochondrial dysfunction, inflammation, senescence and declining cardiomyocyte regeneration. Dietary interventions such as plant-based and ketogenic diets, caloric restriction and macronutrient supplementation are instrumental in maintaining energy balance, reducing adiposity and addressing micronutrient and macronutrient imbalances associated with age-related HF. Therapeutic advancements targeting systemic aging in HF are underway. Key approaches include senomorphics and senolytics to limit senescence, antioxidants targeting mitochondrial stress, anti-inflammatory drugs like interleukin (IL)-1β inhibitors, metabolic rejuvenators such as nicotinamide riboside, resveratrol and sirtuin (SIRT) activators and autophagy enhancers like metformin and sodium-glucose cotransporter 2 (SGLT2) inhibitors, all of which offer potential for preserving cardiac function and alleviating the age-related HF burden.

Pathological insights into activin A: Molecular underpinnings and therapeutic prospects in various diseases

Activin A (Act A) is a member of the TGFβ (transforming growth factor β) superfamily. It communicates via the Suppressor of Mothers against Decapentaplegic Homolog (SMAD2/3) proteins which govern processes such as cell proliferation, wound healing, apoptosis, and metabolism. Act A produces its action by attaching to activin receptor type IIA (ActRIIA) or activin receptor type IIB (ActRIIB). Increasing circulating Act A increases ActRII signalling, which on phosphorylation initiates the ALK4 (activin receptor-like kinase 4) type 1 receptor which further turns on the SMAD pathway and hinders cell functioning. Once triggered, this route leads to gene transcription, differentiation, apoptosis, and extracellular matrix (ECM) formation. Act A also governs the immunological and inflammatory responses of the body, as well as cell death. Moreover, Act A levels have been observed to elevate in several disorders like renal fibrosis, CKD, asthma, NAFLD, cardiovascular diseases, cancer, inflammatory conditions etc. Here, we provide an update on the recent studies relevant to the role of Act A in the modulation of various pathological disorders, giving an overview of the biology of Act A and its signalling pathways, and discuss the possibility of incorporating activin-A targeting as a novel therapeutic approach for the control of various disorders. Pathways such as SMAD signaling, in which SMAD moves to the nucleus by making a complex and leads to tissue fibrosis in CKD, STAT3, which drives renal fibroblast activity and the production of ECM, Kidney injury molecule (KIM-1) in the synthesis, deposition of ECM proteins, SERCA2a (sarcoplasmic reticulum Ca2+ ATPase) in cardiac dysfunction, and NF-κB (Nuclear factor kappa-light-chain-enhancer of activated B cells) in inflammation are involved in Act A signaling, have also been discussed.

Transcriptome Analysis of Myocardial Ischemic-Hypoxic Injury in Rats and Hypoxic H9C2 Cells

AIMS

This study aimed to address inconsistencies in results between the H9C2 myocardial hypoxia (MH) cell line and myocardial infarction (MI) rat models used in MI research. We identified differentially expressed genes (DEGs) and underlying molecular mechanisms using RNA sequencing technology.

METHODS

RNA sequencing was used to analyse DEGs in MI rat tissues and H9C2 cells exposed to hypoxia for 24 h. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to identify key biological processes and pathways. Weighted correlation network analysis [weighted gene co-expression network analysis (WGCNA)] was used to construct gene co-expression networks, and hub genes were compared with published MI datasets [Gene Expression Omnibus (GEO)] for target identification.

RESULTS

GO analysis revealed enrichment of immune inflammation and mitochondrial respiration processes among 5139 DEGs in MI tissues and 2531 in H9C2 cells. KEGG analysis identified 537 overlapping genes associated with metabolism and oxidative stress pathways. Cross-analyses using the published GSE35088 and GSE47495 datasets identified 40 and 16 overlapping genes, respectively, with nine genes overlapping across all datasets and our models. WGCNA identified a key module in the MI model enriched for mRNA processing and protein binding. GO analysis revealed enrichment of mRNA processing, protein binding and mitochondrial respiratory chain complex I assembly in MI and H9C2 MH models. Five relevant hub genes were identified via a cross-analysis between the 92 hub genes that showed a common expression trend in both models.

CONCLUSIONS

This study reveals both shared and distinct transcriptomic responses in the MI and H9C2 models, highlighting the importance of model selection for studying myocardial ischaemia and hypoxia.

Prognostic Significance of Proteomics-Discovered Circulating Inflammatory Biomarkers in Patients With Pulmonary Arterial Hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) ultimately leads to right ventricular failure and premature death. The identification of circulating biomarkers with prognostic utility is considered a priority. As chronic inflammation is recognized as key pathogenic driver, we sought to identify inflammation-related circulating proteins that add incremental value to current risk stratification models for long-term survival in patients with PAH.

METHODS AND RESULTS

Plasma levels of 384 inflammatory proteins were measured with the proximity extension assay technology in patients with PAH (n=60) and controls with normal hemodynamics (n=28). Among these, 51 analytes were significantly overexpressed in the plasma of patients with PAH compared with controls. Cox proportional hazard analyses and C-statistics were performed to assess the prognostic value and the incremental prognostic value of differentially expressed proteins. A panel of 6 proteins (CRIM1 [cysteine rich transmembrane bone morphogenetic protein regulator 1], HGF [hepatocyte growth factor], FSTL3 [follistatin-like 3], PLAUR [plasminogen activator, urokinase receptor], CLSTN2 [calsyntenin 2], SPON1 [spondin 1]) were independently associated with death/lung transplantation at the time of PAH diagnosis after adjustment for the 2015 European Society of Cardiology/European Respiratory Society guidelines, the REVEAL (Registry to Evaluate Early and Long-Term PAH Disease Management) 2.0 risk scores, and the refined 4-strata risk assessment. CRIM1, PLAUR, FSTL3, and SPON1 showed incremental prognostic value on top of the predictive models. As determined by Western blot, FSTL3 and SPON1 were significantly upregulated in the right ventricle of patients with PAH and animal models (monocrotaline-injected and pulmonary artery banding-subjected rats).

CONCLUSIONS

In addition to revealing new actors likely involved in cardiopulmonary remodeling in PAH, our screening identified promising circulating biomarkers to improve risk prediction in PAH, which should be externally confirmed.

Inhibition of activin receptor 2 signalling ameliorates metabolic dysfunction-associated steatotic liver disease in western diet/L-NAME induced cardiometabolic disease

OBJECTIVE

Blockade of activin 2 receptor (ACVR2) signaling has been shown to improve insulin sensitivity and aid in weight loss. Inhibition of ACVR2 signaling restores cardiac function in multiple heart failure models. However, its potential in the treatment of obesity-related cardiometabolic disease remains unknown. Here, we investigated targeting ACVR2 signaling in cardiometabolic disease manifested with metabolic dysfunction-associated steatotic liver disease (MASLD).

METHODS

Mice were fed a high-fat, high-sugar diet combined with the administration of nitric oxide synthase inhibitor L-NAME in drinking water, which causes hypertensive stress. For the last eight weeks, the mice were treated with the soluble ACVR2B decoy receptor (sACVR2B-Fc).

RESULTS

sACVR2B-Fc protected against the development of comorbidities associated with cardiometabolic disease. This was most pronounced in the liver where ACVR2 blockade attenuated the development of MASLD including cessation of pro-fibrotic activation. It also significantly reduced total plasma cholesterol levels, impeded brown adipose tissue whitening, and improved cardiac diastolic function. In vitro, ACVR2 ligands activin A, activin B and GDF11 induced profibrotic signaling and the proliferation of human cardiac fibroblasts.

CONCLUSIONS

Blockade of ACVR2B exerts broad beneficial effects for therapy of cardiometabolic disease. By reducing obesity, ameliorating cardiovascular deterioration and restraining MASLD, blockade of ACVR2B signaling proves a potential target in MASLD and its comorbidities.

Pregnancy, Reproductive Factors, and Female Heart Failure Risk and Outcomes

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of recent evidence on female-specific risk factors related to reproductive status or pregnancy.

RECENT FINDINGS

Pregnancy-related factors, including hypertensive disorders and gestational diabetes, increase the risk of heart failure in women, while breastfeeding and hormone therapy may offer protection. Hypertensive disorders of pregnancy, gestational diabetes, polycystic ovarian syndrome, placental abruption, younger maternal age at first live birth, younger maternal age at last live birth, number of stillbirths, number of pregnancies, onset of menstruation before 12 years of age, shorter reproductive age, ovariectomy, and prolonged absence of ovarian hormones may increase the risk of heart failure in women. Conversely, breastfeeding status and hormone therapy (for menopause or contraception) may serve as protective factors, while fertility treatments have no discernible effect on the risk of heart failure.

Diagnostic and predictive abilities of myokines in patients with heart failure

Myokines are defined as a heterogenic group of numerous cytokines, peptides and metabolic derivates, which are expressed, synthesized, produced, and released by skeletal myocytes and myocardial cells and exert either auto- and paracrine, or endocrine effects. Previous studies revealed that myokines play a pivotal role in mutual communications between skeletal muscles, myocardium and remote organs, such as brain, vasculature, bone, liver, pancreas, white adipose tissue, gut, and skin. Despite several myokines exert complete divorced biological effects mainly in regulation of skeletal muscle hypertrophy, residential cells differentiation, neovascularization/angiogenesis, vascular integrity, endothelial function, inflammation and apoptosis/necrosis, attenuating ischemia/hypoxia and tissue protection, tumor growth and malignance, for other occasions, their predominant effects affect energy homeostasis, glucose and lipid metabolism, adiposity, muscle training adaptation and food behavior. Last decade had been identified 250 more myokines, which have been investigating for many years further as either biomarkers or targets for heart failure management. However, only few myokines have been allocated to a promising tool for monitoring adverse cardiac remodeling, ischemia/hypoxia-related target-organ dysfunction, microvascular inflammation, sarcopenia/myopathy and prediction for poor clinical outcomes among patients with HF. This we concentrate on some most plausible myokines, such as myostatin, myonectin, brain-derived neurotrophic factor, muslin, fibroblast growth factor 21, irisin, leukemia inhibitory factor, developmental endothelial locus-1, interleukin-6, nerve growth factor and insulin-like growth factor-1, which are suggested to be useful biomarkers for HF development and progression.

Dissecting the shared genetic architecture between Alzheimer's disease and frailty: a cross-trait meta-analyses of genome-wide association studies

Introduction: Frailty is the most common medical condition affecting the aging population, and its prevalence increases in the population aged 65 or more. Frailty is commonly diagnosed using the frailty index (FI) or frailty phenotype (FP) assessments. Observational studies have indicated the association of frailty with Alzheimer's disease (AD). However, the shared genetic and biological mechanism of these comorbidity has not been studied. Methods: To assess the genetic relationship between AD and frailty, we examined it at single nucleotide polymorphism (SNP), gene, and pathway levels. Results: Overall, 16 genome-wide significant loci (15 unique loci) (p meta-analysis < 5 × 10-8) and 22 genes (21 unique genes) were identified between AD and frailty using cross-trait meta-analysis. The 8 shared loci implicated 11 genes: CLRN1-AS1, CRHR1, FERMT2, GRK4, LINC01929, LRFN2, MADD, RP11-368P15.1, RP11-166N6.2, RNA5SP459, and ZNF652 between AD and FI, and 8 shared loci between AD and FFS implicated 11 genes: AFF3, C1QTNF4, CLEC16A, FAM180B, FBXL19, GRK4, LINC01104, MAD1L1, RGS12, ZDHHC5, and ZNF521. The loci 4p16.3 (GRK4) was identified in both meta-analyses. The colocalization analysis supported the results of our meta-analysis in these loci. The gene-based analysis revealed 80 genes between AD and frailty, and 4 genes were initially identified in our meta-analyses: C1QTNF4, CRHR1, MAD1L1, and RGS12. The pathway analysis showed enrichment for lipoprotein particle plasma, amyloid fibril formation, protein kinase regulator, and tau protein binding. Conclusion: Overall, our results provide new insights into the genetics of AD and frailty, suggesting the existence of non-causal shared genetic mechanisms between these conditions.

Placental senescence pathophysiology is shared between peripartum cardiomyopathy and preeclampsia in mouse and human

Peripartum cardiomyopathy (PPCM) is an idiopathic form of pregnancy-induced heart failure associated with preeclampsia. Circulating factors in late pregnancy are thought to contribute to both diseases, suggesting a common underlying pathophysiological process. However, what drives this process remains unclear. Using serum proteomics, we identified the senescence-associated secretory phenotype (SASP), a marker of cellular senescence associated with biological aging, as the most highly up-regulated pathway in young women with PPCM or preeclampsia. Placentas from women with preeclampsia displayed multiple markers of amplified senescence and tissue aging, as well as overall increased gene expression of 28 circulating proteins that contributed to SASP pathway enrichment in serum samples from patients with preeclampsia or PPCM. The most highly expressed placental SASP factor, activin A, was associated with cardiac dysfunction or heart failure severity in women with preeclampsia or PPCM. In a murine model of PPCM induced by cardiomyocyte-specific deletion of the gene encoding peroxisome proliferator-activated receptor γ coactivator-1α, inhibiting activin A signaling in the early postpartum period with a monoclonal antibody to the activin type II receptor improved heart function. In addition, attenuating placental senescence with the senolytic compound fisetin in late pregnancy improved cardiac function in these animals. These findings link senescence biology to cardiac dysfunction in pregnancy and help to elucidate the pathogenesis underlying cardiovascular diseases of pregnancy.

Potential regulatory role of epigenetic modifications in aging-related heart failure

Heart failure (HF) is a serious clinical syndrome and a serious development or advanced stage of various heart diseases. Aging is an independent factor that causes pathological damage in cardiomyopathy and participates in the occurrence of HF at the molecular level by affecting mechanisms such as telomere shortening and mitochondrial dysfunction. Epigenetic changes have a significant impact on the aging process, and there is increasing evidence that genetic and epigenetic changes are key features of aging and aging-related diseases. Epigenetic modifications can affect genetic information by changing the chromatin state without changing the DNA sequence. Most of the genetic loci that are highly associated with cardiovascular diseases (CVD) are located in non-coding regions of the genome; therefore, the epigenetic mechanism of CVD has attracted much attention. In this review, we focus on the molecular mechanisms of HF during aging and epigenetic modifications mediating aging-related HF, emphasizing that epigenetic mechanisms play an important role in the pathogenesis of aging-related CVD and can be used as potential diagnostic and prognostic biomarkers, as well as therapeutic targets.

Intrinsic and Extrinsic Contributors to the Cardiac Benefits of Exercise

Among its many cardiovascular benefits, exercise training improves heart function and protects the heart against age-related decline, pathological stress, and injury. Here, we focus on cardiac benefits with an emphasis on more recent updates to our understanding. While the cardiomyocyte continues to play a central role as both a target and effector of exercise's benefits, there is a growing recognition of the important roles of other, noncardiomyocyte lineages and pathways, including some that lie outside the heart itself. We review what is known about mediators of exercise's benefits-both those intrinsic to the heart (at the level of cardiomyocytes, fibroblasts, or vascular cells) and those that are systemic (including metabolism, inflammation, the microbiome, and aging)-highlighting what is known about the molecular mechanisms responsible.

GDF11: An emerging therapeutic target for liver diseases and fibrosis

Growth differentiation factor 11 (GDF11), also known as bone morphogenetic protein 11 (BMP11), has been identified as a key player in various biological processes, including embryonic development, aging, metabolic disorders and cancers. GDF11 has also emerged as a critical component in liver development, injury and fibrosis. However, the effects of GDF11 on liver physiology and pathology have been a subject of debate among researchers due to conflicting reported outcomes. While some studies suggest that GDF11 has anti-aging properties, others have documented its senescence-inducing effects. Similarly, while GDF11 has been implicated in exacerbating liver injury, it has also been shown to have the potential to reduce liver fibrosis. In this narrative review, we present a comprehensive report of recent evidence elucidating the diverse roles of GDF11 in liver development, hepatic injury, regeneration and associated diseases such as non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), liver fibrosis and hepatocellular carcinoma. We also explore the therapeutic potential of GDF11 in managing various liver pathologies.

Analysis of immunoinfiltration and EndoMT based on TGF-β signaling pathway-related genes in acute myocardial infarction

Acute myocardial infarction (AMI), a critical manifestation of coronary heart disease, presents a complex and not entirely understood etiology. This study investigates the potential role of immune infiltration and endothelial-mesenchymal transition (EndoMT) in AMI pathogenesis. We conducted an analysis of the GSE24519 and MSigDB datasets to identify differentially expressed genes associated with the TGF-β signaling pathway (DE-TSRGs) and carried out a functional enrichment analysis. Additionally, we evaluated immune infiltration in AMI and its possible link to myocardial fibrosis. Key genes were identified using machine learning and LASSO logistic regression. The expression of MEOX1 in the ventricular muscles and endothelial cells of Sprague-Dawley rats was assessed through RT-qPCR, immunohistochemical and immunofluorescence assays, and the effect of MEOX1 overexpression on EndoMT was investigated. Our study identified five DE-TSRGs, among which MEOX1, SMURF1, and SPTBN1 exhibited the most significant associations with AMI. Notably, we detected substantial immune infiltration in AMI specimens, with a marked increase in neutrophils and macrophages. MEOX1 demonstrated consistent expression patterns in rat ventricular muscle tissue and endothelial cells, and its overexpression induced EndoMT. Our findings suggest that the TGF-β signaling pathway may contribute to AMI progression by activating the immune response. MEOX1, linked to the TGF-β signaling pathway, appears to facilitate myocardial fibrosis via EndoMT following AMI. These novel insights into the mechanisms of AMI pathogenesis could offer promising therapeutic targets for intervention.

Unlocking the dark matter: noncoding RNAs and RNA modifications in cardiac aging

Cardiac aging is a multifaceted process that encompasses structural and functional alterations culminating in heart failure. As the elderly population continues to expand, there is a growing urgent need for interventions to combat age-related cardiac functional decline. Noncoding RNAs have emerged as critical regulators of cellular and biochemical processes underlying cardiac disease. This review summarizes our current understanding of how noncoding RNAs function in the heart during aging, with particular emphasis on mechanisms of RNA modification that control their activity. Targeting noncoding RNAs as potential novel therapeutics in cardiac aging is also discussed.

Roles of Activin A and Gpnmb in Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

Metabolic dysfunction-associated steatotic liver disease (MASLD, formerly known as nonalcoholic fatty liver disease [NAFLD]) and metabolic dysfunction-associated steatohepatitis (MASH, formerly known as nonalcoholic steatohepatitis [NASH]) are leading chronic liver diseases, driving cirrhosis, hepatocellular carcinoma, and mortality. MASLD/MASH is associated with increased senescence proteins, including Activin A, and senolytics have been proposed as a therapeutic approach. To test the role of Activin A, we induced hepatic expression of Activin A in a murine MASLD/MASH model. Surprisingly, overexpression of hepatic Activin A dramatically mitigated MASLD, reducing liver steatosis and inflammation as well as systemic fat accumulation, while improving insulin sensitivity. Further studies identified a dramatic decrease in the lipid-associated macrophages marker glycoprotein NMB (Gpnmb) by Activin A, and Gpnmb knockdown in the same model produced similar benefits and transcriptional changes to Activin A expression. These studies reveal a surprising protective role for Activin A in MASLD and the potential for SASP proteins to have context-specific beneficial effects. Moreover, they implicate both Activin A and Gpnmb as potential therapeutic targets for this condition.

ARTICLE HIGHLIGHTS

Large scale plasma proteomics identifies novel proteins and protein networks associated with heart failure development

Heart failure (HF) causes substantial morbidity and mortality but its pathobiology is incompletely understood. The proteome is a promising intermediate phenotype for discovery of novel mechanisms. We measured 4877 plasma proteins in 13,900 HF-free individuals across three analysis sets with diverse age, geography, and HF ascertainment to identify circulating proteins and protein networks associated with HF development. Parallel analyses in Atherosclerosis Risk in Communities study participants in mid-life and late-life and in Trøndelag Health Study participants identified 37 proteins consistently associated with incident HF independent of traditional risk factors. Mendelian randomization supported causal effects of 10 on HF, HF risk factors, or left ventricular size and function, including matricellular (e.g. SPON1, MFAP4), senescence-associated (FSTL3, IGFBP7), and inflammatory (SVEP1, CCL15, ITIH3) proteins. Protein co-regulation network analyses identified 5 modules associated with HF risk, two of which were influenced by genetic variants that implicated trans hotspots within the VTN and CFH genes.

Circulating Growth Differentiation Factors 11 and 8, Their Antagonists Follistatin and Follistatin-Like-3, and Risk of Heart Failure in Elders

BACKGROUND

Heterochronic parabiosis has identified growth differentiation factor (GDF)-11 as a potential means of cardiac rejuvenation, but findings have been inconsistent. A major barrier has been lack of assay specificity for GDF-11 and its homolog GDF-8.

METHODS

We tested the hypothesis that GDF-11 and GDF-8, and their major antagonists follistatin and follistatin-like (FSTL)-3, are associated with incident heart failure (HF) and its subtypes in elders. Based on validation experiments, we used liquid chromatography-tandem mass spectrometry to measure total serum GDF-11 and GDF-8, along with follistatin and FSTL-3 by immunoassay, in 2 longitudinal cohorts of older adults.

RESULTS

In 2 599 participants (age 75.2 ± 4.3) followed for 10.8 ± 5.6 years, 721 HF events occurred. After adjustment, neither GDF-11 (HR per doubling: 0.93 [0.67, 1.30]) nor GDF-8 (HR: 1.02 per doubling [0.83, 1.27]) was associated with incident HF or its subtypes. Positive associations with HF were detected for follistatin (HR: 1.15 [1.00, 1.32]) and FLST-3 (HR: 1.38 [1.03, 1.85]), and with HF with preserved ejection fraction for FSTL-3 (HR: 1.77 [1.03, 3.02]). (All HRs per doubling of biomarker.) FSTL-3 associations with HF appeared stronger at higher follistatin levels and vice versa, and also for men, Blacks, and lower kidney function.

CONCLUSIONS

Among older adults, serum follistatin and FSTL-3, but not GDF-11 or GDF-8, were associated with incident HF. These findings do not support the concept that low serum levels of total GDF-11 or GDF-8 contribute to HF late in life, but do implicate transforming growth factor-β superfamily pathways as potential therapeutic targets.

Identification and exploration of aging-related subtypes and distinctive role of SERPINE1 in heart failure based on single-cell and bulk RNA sequencing data

Aging is a major risk factor for heart failure (HF) and is the leading cause of death worldwide. Currently, the nature of the relationship between aging and HF is not entirely clear. Herein, this study aimed to explore new diagnostic biomarkers, molecular typing and therapeutic strategies for HF by investigating the biological significance of aging-related genes in HF. A total of 157 differentially expressed genes (DEGs) were screened totally between HF and normal samples, and functional enrichment analysis of DEGs revealed the strong association of HF progression with aging, immune processes and metabolism. Six HF-specific aging-related genes were further identified, and a diagnostic model was developed and validated for good diagnostic efficacy. In addition, we collected blood samples from 10 normal controls and 10 HF patients for RT-qPCR analysis to verify the bioinformation. We also identified two aging-associated subtypes with distinctly different immune infiltration and metabolic microenvironment. Further single-cell sequencing analysis conducted in the study identified SERPINE1 as a key gene in HF. The distinctive role of SERPINE1 fibroblasts was revealed, including three main findings: (I) fibroblasts had a higher proportion and expression of SERPINE1 levels in HF; (II) the ligand-receptor pair MDK-LRP1 made the most contributions in high interactions with other cell types in SERPINE1 fibroblasts; and (III) SERPINE1 fibroblasts were associated with the interaction of extracellular matrix and receptor and may be regulated by the transcription factor EGR1. In conclusion, this study highlights the importance of aging-related genes in diagnosing HF and regulating immune infiltration. We also identified different HF subtypes and a potentially crucial gene, which may provide a better understanding of the molecular-level mechanisms of aging-related HF and aid in developing effective therapeutic strategies.

Circulating GDF11 exacerbates myocardial injury in mice and associates with increased infarct size in humans

AIMS

The heart rejuvenating effects of circulating growth differentiation factor 11 (GDF11), a transforming growth factor-β superfamily member that shares 90% homology with myostatin (MSTN), remains controversial. Here, we aimed to probe the role of GDF11 in acute myocardial infarction (MI), a frequent cause of heart failure and premature death during ageing.

METHODS AND RESULTS

In contrast to endogenous Mstn, myocardial Gdf11 declined during the course of ageing and was particularly reduced following ischaemia/reperfusion (I/R) injury, suggesting a therapeutic potential of GDF11 signalling in MI. Unexpectedly, boosting systemic Gdf11 by recombinant GDF11 delivery (0.1 mg/kg body weight over 30 days) prior to myocardial I/R augmented myocardial infarct size in C57BL/6 mice irrespective of their age, predominantly by accelerating pro-apoptotic signalling. While intrinsic cardioprotective signalling pathways remained unaffected by high circulating GDF11, targeted transcriptomics and immunomapping studies focusing on GDF11-associated downstream targets revealed attenuated Nkx2-5 expression confined to CD105-expressing cells, with pro-apoptotic activity, as assessed by caspase-3 levels, being particularly pronounced in adjacent cells, suggesting an indirect effect. By harnessing a highly specific and validated liquid chromatography-tandem mass spectrometry-based assay, we show that in prospectively recruited patients with MI circulating GDF11 but not MSTN levels incline with age. Moreover, GDF11 levels were particularly elevated in those at high risk for adverse outcomes following the acute event, with circulating GDF11 emerging as an independent predictor of myocardial infarct size, as estimated by standardized peak creatine kinase-MB levels.

CONCLUSION

Our data challenge the initially reported heart rejuvenating effects of circulating GDF11 and suggest that high levels of systemic GDF11 exacerbate myocardial injury in mice and humans alike. Persistently high GDF11 levels during ageing may contribute to the age-dependent loss of cardioprotective mechanisms and thus poor outcomes of elderly patients following acute MI.

Association of activin A and postpartum blood pressure in peripartum cardiomyopathy

BACKGROUND

Activin A has been implicated in the pathogenesis of patients with chronic hypertension and heart failure as well as patients with hypertensive disorders of pregnancy (HDP). Whether activin A correlates with blood pressure in patients with peripartum cardiomyopathy (PPCM) and HDP history has not previously been explored.

METHODS AND RESULTS

82 women with PPCM w/ and w/out HDP or hypertension history were selected for analysis from the Investigations in Pregnancy Associated Cardiomyopathy (IPAC) study. Serum biomarkers and blood pressure were assessed at the time of enrollment (median postpartum day 24). Levels of both sFlt-1 (SBP: r 0.47, p = 0.008; DBP: r 0.57, p < 0.001) and activin A (SBP: r 0.59, p < 0.001;DBP: r 0.68, p < 0.001) were noted to significantly correlate with blood pressure in patients with a history of HDP who went on to develop PPCM, but not in patients with chronic hypertension or no hypertensive history. The strongest correlation was between activin A levels and postpartum diastolic blood pressure for the subset with preeclampsia (DBP: r0.82, p < 0.001). This remained significant in multivariable linear regression analysis (DBP: β = 0.011, p = 0.015).

CONCLUSION

In patients with PPCM, activin A and sFlt-1 levels had direct correlations with both systolic (SBP) and diastolic blood pressures (DBP), but only in participants with history of HDP. This correlation was more evident for activin A and strongest with a history of preeclampsia. Our findings suggest that activin A may play an important role in blood pressure modulation in women with HDP who subsequently develop PPCM.

Evaluation of Associations of Growth Differentiation Factor-11, Growth Differentiation Factor-8, and Their Binding Proteins, Follistatin and Follistatin-Like Protein-3, With Measures of Skeletal Muscle Mass, Muscle Strength, and Physical Function in Older Adults

BACKGROUND

Based on studies from animal models, growth differentiation factor-11 (GDF-11) may have rejuvenating effects in humans. GDF-11 has high sequence homology with GDF-8 (also known as myostatin); follistatin and follistatin-like protein-3 (FSTL-3) are inhibitory proteins of both GDF-8 and GDF-11.

METHODS

Using highly specific liquid chromatography with tandem mass spectrometry assays for GDF-11 and GDF-8 and immunoassays for follistatin and FSTL-3, we quantified the association of these factors with muscle size, strength, and physical performance in 2 prospective cohort studies of community-dwelling older adults (Health, Aging, and Body Composition study [Health ABC] and Cardiovascular Health Study [CHS]).

RESULTS

GDF-8 levels were positively associated with thigh muscle cross-sectional area and density in Health ABC (data not available in CHS). GDF-8 levels were positively associated with lean mass (a surrogate of muscle mass) in Health ABC but not CHS, and grip strength in CHS but not Health ABC. FSTL-3 (and perhaps follistatin) was negatively associated with lean mass and had variable associations with other variables. In contrast, GDF-11 was not significantly associated with strength or performance.

CONCLUSIONS

GDF-8 and its binding proteins, follistatin and FSTL-3, may constitute a counterregulatory system (chalones) to restrain age-related loss of muscle mass and strength.

Frailty Resilience Score: A Novel Measure of Frailty Resilience Associated With Protection From Frailty and Survival

Frailty is characterized by increased vulnerability to disability and high risk for mortality in older adults. Identification of factors that contribute to frailty resilience is an important step in the development of effective therapies that protect against frailty. First, a reliable quantification of frailty resilience is needed. We developed a novel measure of frailty resilience, the Frailty Resilience Score (FRS), that integrates frailty genetic risk, age, and sex. Application of FRS to the LonGenity cohort (n = 467, mean age 74.4) demonstrated its validity compared to phenotypic frailty and its utility as a reliable predictor of overall survival. In a multivariable-adjusted analysis, 1-standard deviation increase in FRS predicted a 38% reduction in the hazard of mortality, independent of baseline frailty (p < .001). Additionally, FRS was used to identify a proteomic profile of frailty resilience. FRS was shown to be a reliable measure of frailty resilience that can be applied to biological studies of resilience.

Immune Markers, Blood Pressure Severity, and Cardiac Remodeling 1 to 2 Years After Hypertensive Disorders of Pregnancy

Background Cardiovascular dysfunction and hypertension can persist postpartum following hypertensive disorders of pregnancy (HDPs). This study hypothesized that activin A, proinflammatory markers and concentric remodeling by echo would be higher 1-2 years postpartum following HDP with persistent hypertension compared to HDP with normalized blood pressure (BP). We further hypothesized correlations between biomarkers with BP and echocardiographic indices. Methods and Results This study enrolled participants with HDPs but no prepregnancy hypertension followed 1 to 2 years after delivery. Activin A and inflammatory cytokines, BP, and echocardiograms were obtained. Biomarker concentrations and echocardiographic parameters were compared between HDP with and without persistent hypertension. Individuals with persistent hypertension at a mean of 1.6 years postpartum had significantly higher activin A concentrations (median[interquartile range 25-75] 230.6 [196.0-260.9] versus 175.3 pg/mL [164.3-188.4]; P<0.01), more concentric left ventricular concentric remodeling (relative wall thickness >0.42, 48% versus 7%; P<0.01), and worse peak left atrial strain (33.4% versus 39.3%; P<0.05) as compared with those whose BP normalized. Higher activin A and interleukin-6 concentrations correlated with higher systolic (activin A: r=0.43, P=0.01) and diastolic BP (activin A: r=0.58, P<0.01; interleukin-6: r=0.36; P<0.05), as well as greater left ventricular thickness (activin A and interventricular septal thickness: r=0.41, interleukin-6 and interventricular septal thickness: r=0.36; both P<0.05). Conclusions Individuals with HDPs and persistent hypertension had significantly higher activin A and greater concentric remodeling compared with those with HDPs and normalized BP at 1 to 2 years postpartum. Activin A was positively correlated with both BP and echocardiographic indices (left ventricular thickness), suggesting overlapping processes between persistent hypertension and cardiac remodeling.

GDF11 and aging biology - controversies resolved and pending

Since the exogenous administration of GDF11, a TGF-ß superfamily member, was reported to have beneficial effects in some models of human disease, there have been many research studies in GDF11 biology. However, many studies have now confirmed that exogenous administration of GDF11 can improve physiology in disease models, including cardiac fibrosis, experimental stroke, and disordered metabolism. GDF11 is similar to GDF8 (also called Myostatin), differing only by 11 amino acids in their mature signaling domains. These two proteins are now known to be biochemically different both in vitro and in vivo. GDF11 is much more potent than GDF8 and induces more strongly SMAD2 phosphorylation in the myocardium compared to GDF8. GDF8 and GDF11 prodomain are only 52% identical and are cleaved by different Tolloid proteases to liberate the mature signaling domain from inhibition of the prodomain. Here, we review the state of GDF11 biology, highlighting both resolved and remaining controversies.

Inflammatory Mechanisms in Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is now the most common form of heart failure and a significant public health concern for which limited effective therapies exist. Inflammation triggered by comorbidity burden is a critical element of HFpEF pathophysiology. Here, we discuss evidence for comorbidity-driven systemic and myocardial inflammation and the mechanistic role of inflammation in pathological myocardial remodeling in HFpEF.

Characterization of a robust mouse model of heart failure with preserved ejection fraction

Heart failure (HF) is a leading cause of morbidity and mortality particularly in older adults and patients with multiple metabolic comorbidities. Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome with multisystem organ dysfunction in which patients develop symptoms of HF as a result of high left ventricular (LV) diastolic pressure in the context of normal or near normal LV ejection fraction (LVEF; ≥50%). Challenges to create and reproduce a robust rodent phenotype that recapitulates the multiple comorbidities that exist in this syndrome explain the presence of various animal models that fail to satisfy all the criteria of HFpEF. Using a continuous infusion of angiotensin II and phenylephrine (ANG II/PE), we demonstrate a strong HFpEF phenotype satisfying major clinically relevant manifestations and criteria of this pathology, including exercise intolerance, pulmonary edema, concentric myocardial hypertrophy, diastolic dysfunction, histological signs of microvascular impairment, and fibrosis. Conventional echocardiographic analysis of diastolic dysfunction identified early stages of HFpEF development and speckle tracking echocardiography analysis including the left atrium (LA) identified strain abnormalities indicative of contraction-relaxation cycle impairment. Diastolic dysfunction was validated by retrograde cardiac catheterization and analysis of LV end-diastolic pressure (LVEDP). Among mice that developed HFpEF, two major subgroups were identified with predominantly perivascular fibrosis and interstitial myocardial fibrosis. In addition to major phenotypic criteria of HFpEF that were evident at early stages of this model (3 and 10 days), accompanying RNAseq data demonstrate activation of pathways associated with myocardial metabolic changes, inflammation, activation of extracellular matrix (ECM) deposition, microvascular rarefaction, and pressure- and volume-related myocardial stress.NEW & NOTEWORTHY Heart failure with preserved ejection fraction (HFpEF) is an emerging epidemic affecting up to half of patients with heart failure. Here we used a chronic angiotensin II/phenylephrine (ANG II/PE) infusion model and instituted an updated algorithm for HFpEF assessment. Given the simplicity in generating this model, it may become a useful tool for investigating pathogenic mechanisms, identification of diagnostic markers, and for drug discovery aimed at both prevention and treatment of HFpEF.

Challenges and Future Prospects of Targeting Myostatin/Activin A Signaling to Treat Diseases of Muscle Loss and Metabolic Dysfunction

Over the past 25 years, considerable progress has been made in terms of elucidating the regulatory and signaling mechanisms underlying the control of skeletal muscle mass by myostatin and other secreted proteins belonging to the transforming growth factor-β superfamily. Preclinical studies demonstrating the potential benefits of targeting the activities of these ligands have fueled the development of numerous biologics capable of perturbing this signaling pathway and increasing muscle mass and function. These biologics have been tested in numerous clinical trials for a wide range of indications characterized by muscle loss and excess adiposity. Here, we review the results of these trials and discuss some of the challenges and future prospects for targeting this signaling pathway to treat muscle and metabolic diseases. Myostatin inhibitors may improve metabolic outcomes by increasing muscle mass, and metabolic disorders may be attractive potential indications for these molecules.

Uncovering new insights into the role of the ubiquitin ligase Smurf1 on the regulation of innate immune signaling and resistance to infection

Innate immunity is the body's first line of defense against infections. Innate immune cells express pattern recognition receptors in distinct cellular compartments that are responsible to detect either pathogens-associated molecules or cellular components derived from damaged cells, to trigger intracellular signaling pathways that lead to the activation of inflammatory responses. Inflammation is essential to coordinate immune cell recruitment, pathogen elimination and to keep normal tissue homeostasis. However, uncontrolled, misplaced or aberrant inflammatory responses could lead to tissue damage and drive chronic inflammatory diseases and autoimmunity. In this context, molecular mechanisms that tightly regulate the expression of molecules required for the signaling of innate immune receptors are crucial to prevent pathological immune responses. In this review, we discuss the ubiquitination process and its importance in the regulation of innate immune signaling and inflammation. Then, we summarize the roles of Smurf1, a protein that works on ubiquitination, on the regulation of innate immune signaling and antimicrobial mechanisms, emphasizing its substrates and highlighting its potential as a therapeutic target for infectious and inflammatory conditions.

Long-term dietary n3 fatty acid prevents aging-related cardiac diastolic and vascular dysfunction

AIMS

The prevalence of left ventricular (LV) diastolic and vascular dysfunction increases with age, eventually leading to heart failure with preserved ejection fraction (HFpEF). A preventive strategy is an unmet medical need. We and others reported previously on the beneficial effects of omega-3 fatty acid alpha linolenic acid (ALA) on cardiovascular disorders in animal models and translational studies. We now investigate whether long-term dietary ALA could prevent LV diastolic dysfunction and vascular aging in a murine model.

METHODS AND RESULTS

Wild-type C57BL/6 J mice were fed a chow or ALA diet for 12 months, starting at 6 months of age. Here, we show that aged (~18 months) mice recapitulate major hallmarks of HFpEF, including LV diastolic dysfunction with preserved ejection fraction, impaired vascular function, cardiac fibrosis, arterial stiffening and inflammation, as well as elevated B-type natriuretic peptide (BNP). Long-term ALA supplementation upregulated the mitochondrial tricarboxylic acid enzyme Idh2 and the antioxidant enzymes SOD1 and Gpx1. It also has been associated with reduced inflammation and ECM remodeling, accompanied by a significant downregulation of fibrosis biomarkers MMP-2 and TGF-β in both cardiac and vascular tissues obtained from aged mice. Our data exhibited the preventive effects of dietary ALA against LV diastolic dysfunction, impaired vasorelaxation, cardiac fibrosis, inflammation and arterial stiffening in aged mice.

CONCLUSIONS

We provide evidence and a simplified mechanistic insight on how long-term ALA supplementation is a successful strategy to prevent the development of age-related diastolic and vascular dysfunction.

Inactivating the Uninhibited: The Tale of Activins and Inhibins in Pulmonary Arterial Hypertension

Advances in technology and biomedical knowledge have led to the effective diagnosis and treatment of an increasing number of rare diseases. Pulmonary arterial hypertension (PAH) is a rare disorder of the pulmonary vasculature that is associated with high mortality and morbidity rates. Although significant progress has been made in understanding PAH and its diagnosis and treatment, numerous unanswered questions remain regarding pulmonary vascular remodeling, a major factor contributing to the increase in pulmonary arterial pressure. Here, we discuss the role of activins and inhibins, both of which belong to the TGF-β superfamily, in PAH development. We examine how these relate to signaling pathways implicated in PAH pathogenesis. Furthermore, we discuss how activin/inhibin-targeting drugs, particularly sotatercep, affect pathophysiology, as these target the afore-mentioned specific pathway. We highlight activin/inhibin signaling as a critical mediator of PAH development that is to be targeted for therapeutic gain, potentially improving patient outcomes in the future.

Lysophospholipids and branched chain amino acids are associated with aging: a metabolomics-based study of Chinese adults

BACKGROUND

Aging is an inevitable process associated with impairments in multiple organ systems, which increases the risk of comorbidity and disability, and reduces the health-span. Metabolomics is a powerful tool in aging research, which can reflect the characteristics of aging at the level of terminal metabolism, and may contribute to the exploration of aging mechanisms and the formulation of anti-aging strategies.

METHODS

To identify possible biomarkers and pathways associated with aging using untargeted metabolomics methods, we performed liquid chromatography-mass spectrometry (LC-MS)-based untargeted metabolomics profiling on serum samples from 32 older adults and 32 sex-matched young controls.

RESULTS

Metabolite profiling could distinguish the two groups. Among the 349 metabolites identified, 80-including lysophospholipids whose levels gradually decline-are possible candidate aging biomarkers. Valine, leucine and isoleucine degradation and biosynthesis were important pathways in aging, with reduced levels of L-isoleucine (r = - 0.30, p = 0.017) and L-leucine (r = - 0.32, p = 0.010) observed in older adults.

CONCLUSIONS

We preliminarily revealed the metabolite changes associated with aging in Chinese adults. Decreases in mitochondrial membrane-related lysophospholipids and dysfunction of branched-chain amino acid metabolism were determined to be the characteristics and promising research targets for aging.

Beneficial Effects of Moderate Hepatic Activin A Expression on Metabolic Pathways, Inflammation, and Atherosclerosis

BACKGROUND

Atherosclerosis is an inflammatory vascular disease marked by hyperlipidemia and hematopoietic stem cell expansion. Activin A, a member of the Activin/GDF/TGFβ/BMP (growth/differentiation factor/transforming growth factor beta/bone morphogenetic protein) family is broadly expressed and increases in human atherosclerosis, but its functional effects in vivo in this context remain unclear.

METHODS

We studied LDLR^-/- mice on a Western diet for 12 weeks and used adeno-associated viral vectors with a liver-specific TBG (thyroxine-binding globulin) promoter to express Activin A or GFP (control). Atherosclerotic lesions were analyzed by oil red staining. Blood lipid profiling was performed by high-performance liquid chromatography, and immune cells were evaluated by flow cytometry. Liver RNA-sequencing was performed to explore the underlying mechanisms.

RESULTS

Activin A expression decreased in both livers and aortae from LDLR^-/- mice fed a Western diet compared with standard laboratory diet. Adenoassociated virus-TBG-Activin A increased Activin A hepatic expression ≈10-fold at 12 weeks; P<0.001) and circulating Activin A levels ≈2000 pg/ml versus ≈50 pg/ml; P<0.001, compared with controls). Hepatic Activin A expression decreased plasma total and LDL (low-density lipoprotein) cholesterol ≈60% and ≈40%, respectively), reduced inflammatory cells in aortae and proliferating hematopoietic stem cells in bone marrow, and reduced atherosclerotic lesion and necrotic core area in aortae. Activin A also attenuated liver steatosis and expression of the lipogenesis genes, Srebp1 and Srebp2. RNA sequencing revealed Activin A not only blocked expression of genes involved in hepatic de novo lipogenesis but also fatty acid uptake and liver inflammation. In addition, Activin A expressed in the liver also reduced white fat tissue accumulation, decreased adipocyte size, and improved glucose tolerance.

CONCLUSIONS

Our studies reveal hepatic Activin A expression reduces inflammation, hematopoietic stem cell expansion, liver steatosis, circulating cholesterol, and fat accumulation, which likely all contribute to the observed protection against atherosclerosis. The reduced Activin A observed in LDLR^-/- mice on a Western diet seems maladaptive and deleterious for atherogenesis.

Sotatercept analog improves cardiopulmonary remodeling and pulmonary hypertension in experimental left heart failure

Pulmonary hypertension due to left heart disease (PH-LHD) is the most frequent manifestation of PH but lacks any approved treatment. Activin receptor type IIA-Fc fusion protein (ActRIIA-Fc) was found previously to be efficacious in experimental and human pulmonary arterial hypertension (PAH). Here we tested the hypothesis that ActRIIA-Fc improves pulmonary vascular remodeling and alleviates PH in models of PH-LHD, specifically in subtypes of heart failure with reduced ejection fraction (PH-HFrEF) and preserved ejection fraction (PH-HFpEF). Treatment with murine ActRIIA-Fc reduced cardiac remodeling and improved cardiac function in two mouse models of left heart disease without PH, confirming that this inhibitor of activin-class ligand signaling can exert cardioprotective effects in heart failure. In a mouse model of PH-HFrEF with prolonged pressure overload caused by transverse aortic constriction, ActRIIA-Fc treatment significantly reduced pulmonary vascular remodeling, pulmonary fibrosis, and pulmonary hypertension while exerting beneficial structural, functional, and histological effects on both the left and right heart. Additionally, in an obese ZSF1-SU5416 rat model of PH-HFpEF with metabolic dysregulation, therapeutic treatment with ActRIIA-Fc normalized SMAD3 overactivation in pulmonary vascular and perivascular cells, reversed pathologic pulmonary vascular and cardiac remodeling, improved pulmonary and cardiac fibrosis, alleviated PH, and produced marked functional improvements in both cardiac ventricles. Studies in vitro revealed that treatment with ActRIIA-Fc prevents an abnormal, glucose-induced, activin-mediated, migratory phenotype in human pulmonary artery smooth muscle cells, providing a mechanism by which ActRIIA-Fc could exert therapeutic effects in experimental PH-HFpEF with metabolic dysregulation. Our results demonstrate that ActRIIA-Fc broadly corrects cardiopulmonary structure and function in experimental PH-LHD, including models of PH-HFrEF and PH-HFpEF, leading to alleviation of PH under diverse pathophysiological conditions. These findings highlight the important pathogenic contributions of activin-class ligands in multiple forms of experimental PH and support ongoing clinical evaluation of human ActRIIA-Fc (sotatercept) in patients with PH-HFpEF.

Adiponectin, the adiponectin paradox, and Alzheimer's Disease: Is this association biologically plausible?

Dementia, especially Alzheimer's Disease (AD) and vascular dementia, is a major public health problem that continues to expand in both economically emerging and hegemonic countries. In 2017, the World Alzheimer Report estimated that over 50 million people were living with dementia globally. Metabolic dysfunctions of brain structures such as the hippocampus and cerebral cortex have been implicated as risk factors for dementia. Several well-defined metabolic risk factors for AD include visceral obesity, chronic inflammation, peripheral and brain insulin resistance, type 2 diabetes mellitus (T2DM), hypercholesterolemia, and others. In this review, we describe the relationship between the dysmetabolic mechanisms, although still unknown, and dementia, particularly AD. Adiponectin (ADPN), the most abundant circulating adipocytokine, acts as a protagonist in the metabolic dysfunction associated with AD, with unexpected and intriguing dual biological functions. This contradictory role of ADPN has been termed the adiponectin paradox. Some evidence suggests that the adiponectin paradox is important in amyloidogenic evolvability in AD. We present cumulative evidence showing that AD and T2DM share many common features. We also review the mechanistic pathways involving brain insulin resistance. We discuss the importance of the evolvability of amyloidogenic proteins (APs), defined as the capacity of a system for adaptive evolution. Finally, we describe potential therapeutic strategies in AD, based on the adiponectin paradox.

The Aging Heart: A Molecular and Clinical Challenge

Aging is associated with an increasing burden of morbidity, especially for cardiovascular diseases (CVDs). General cardiovascular risk factors, ischemic heart diseases, heart failure, arrhythmias, and cardiomyopathies present a significant prevalence in older people, and are characterized by peculiar clinical manifestations that have distinct features compared with the same conditions in a younger population. Remarkably, the aging heart phenotype in both healthy individuals and patients with CVD reflects modifications at the cellular level. An improvement in the knowledge of the physiological and pathological molecular mechanisms underlying cardiac aging could improve clinical management of older patients and offer new therapeutic targets.

GDF11 Is a Novel Protective Factor Against Vascular Calcification

ABSTRACT

Vascular calcification (VC) occurs via an active cell-mediated process, which involves osteogenic differentiation, apoptosis, and phenotypic transformation of vascular smooth muscle cells (VSMCs). As a member of the transforming growth factor-β family, growth differentiation factor 11 (GDF11) can inhibit apoptosis and osteogenic differentiation and maintain the stability of atherosclerotic plaques. In this study, coronary artery calcium score (CACS) of participants with GDF11 measurements was measured using computed tomography angiography and was scored according to the Agatston score. β-glycerophosphate (10 mM), dexamethasone (100 nM), and l -ascorbic acid (50 µg/mL) [osteogenic medium (OM)] were used to induce calcification of human aortic smooth muscle cells. We found that CACS was negatively correlated with serum GDF11 levels in patients and GDF11 was a strong predictor of elevated CACS (OR = 0.967, 95% CI: 0.945-0.991; P = 0.006), followed by age (OR = 1.151, 95% CI: 1.029-1.286; P = 0.014), triglycerides (OR = 4.743, 95% CI: 1.170-19.236; P = 0.029), C-reactive protein (OR = 1.230, 95% CI: 1.010-1.498; P = 0.04), and hypertension (OR = 7.264, 95% CI: 1.099-48.002; P = 0.04). Furthermore, exogenous GDF11 inhibited OM-induced calcification by inhibiting osteogenic differentiation, the phenotypic transformation and apoptosis of human aortic smooth muscle cells. Our study demonstrates that GDF11 plays a crucial role in reducing vascular calcification and serves as a potential intervention target to vascular calcification.

Plasma proteomic signature of decline in gait speed and grip strength

The biological mechanisms underlying decline in physical function with age remain unclear. We examined the plasma proteomic profile associated with longitudinal changes in physical function measured by gait speed and grip strength in community-dwelling adults. We applied an aptamer-based platform to assay 1154 plasma proteins on 2854 participants (60% women, aged 76 years) in the Cardiovascular Health Study (CHS) in 1992-1993 and 1130 participants (55% women, aged 54 years) in the Framingham Offspring Study (FOS) in 1991-1995. Gait speed and grip strength were measured annually for 7 years in CHS and at cycles 7 (1998-2001) and 8 (2005-2008) in FOS. The associations of individual protein levels (log-transformed and standardized) with longitudinal changes in gait speed and grip strength in two populations were examined separately by linear mixed-effects models. Meta-analyses were implemented using random-effects models and corrected for multiple testing. We found that plasma levels of 14 and 18 proteins were associated with changes in gait speed and grip strength, respectively (corrected p < 0.05). The proteins most strongly associated with gait speed decline were GDF-15 (Meta-analytic p = 1.58 × 10-15 ), pleiotrophin (1.23 × 10-9 ), and TIMP-1 (5.97 × 10-8 ). For grip strength decline, the strongest associations were for carbonic anhydrase III (1.09 × 10-7 ), CDON (2.38 × 10-7 ), and SMOC1 (7.47 × 10-7 ). Several statistically significant proteins are involved in the inflammatory responses or antagonism of activin by follistatin pathway. These novel proteomic biomarkers and pathways should be further explored as future mechanisms and targets for age-related functional decline.

The activin receptor ligand trap ActRIIB:ALK4-Fc ameliorates cardiomyopathy induced by neuromuscular disease and diabetes

Cardiomyopathies are ascribed to a variety of etiologies, present with diverse clinical phenotypes, and lack disease-modifying treatments. Mounting evidence implicates dysregulated activin receptor signaling in heart disease and highlights inhibition of this pathway as a potential therapeutic target. Here, we explored the effects of activin ligand inhibition using ActRIIB:ALK4-Fc, a heterodimeric receptor fusion protein, in two mechanistically distinct murine models of cardiomyopathy. Treatment with ActRIIB:ALK4-Fc significantly improved systolic or diastolic function in cardiomyopathy induced by neuromuscular disease or diabetes mellitus. Moreover, ActRIIB:ALK4-Fc corrected Ca²⁺ handling protein expression in diseased heart tissues, suggesting that activin signaling inhibition could alleviate cardiomyopathies in part by rebalancing aberrant intracellular Ca²⁺ homeostasis-a common underlying pathomechanism in diverse heart diseases.

Activin A directly impairs human cardiomyocyte contractile function indicating a potential role in heart failure development

Activin A has been linked to cardiac dysfunction in aging and disease, with elevated circulating levels found in patients with hypertension, atherosclerosis, and heart failure. Here, we investigated whether Activin A directly impairs cardiomyocyte (CM) contractile function and kinetics utilizing cell, tissue, and animal models. Hydrodynamic gene delivery-mediated overexpression of Activin A in wild-type mice was sufficient to impair cardiac function, and resulted in increased cardiac stress markers (N-terminal pro-atrial natriuretic peptide) and cardiac atrophy. In human-induced pluripotent stem cell-derived (hiPSC) CMs, Activin A caused increased phosphorylation of SMAD2/3 and significantly upregulated SERPINE1 and FSTL3 (markers of SMAD2/3 activation and activin signaling, respectively). Activin A signaling in hiPSC-CMs resulted in impaired contractility, prolonged relaxation kinetics, and spontaneous beating in a dose-dependent manner. To identify the cardiac cellular source of Activin A, inflammatory cytokines were applied to human cardiac fibroblasts. Interleukin -1β induced a strong upregulation of Activin A. Mechanistically, we observed that Activin A-treated hiPSC-CMs exhibited impaired diastolic calcium handling with reduced expression of calcium regulatory genes (SERCA2, RYR2, CACNB2). Importantly, when Activin A was inhibited with an anti-Activin A antibody, maladaptive calcium handling and CM contractile dysfunction were abrogated. Therefore, inflammatory cytokines may play a key role by acting on cardiac fibroblasts, causing local upregulation of Activin A that directly acts on CMs to impair contractility. These findings demonstrate that Activin A acts directly on CMs, which may contribute to the cardiac dysfunction seen in aging populations and in patients with heart failure.

Roles of follistatin-like protein 3 in human non-tumor pathophysiologies and cancers

Follistatin-like protein 3 (FSTL3) is a type of FSTLs. By interacting with a disintegrin and metalloproteinase 12 (ADAM12), transforming growth factor-β ligands (activin, myostatin and growth differentiation factor (GDF) 11), FSTL3 can either activate or inhibit these molecules in human non-tumor pathophysiologies and cancers. The FSTL3 gene was initially discovered in patients with in B-cell chronic lymphocytic leukemia, and subsequent studies have shown that the FSTL3 protein is associated with reproductive development, insulin resistance, and hematopoiesis. FSTL3 reportedly contributes to the development and progression of many cancers by promoting tumor metastasis, facilitating angiogenesis, and inducing stem cell differentiation. This review summarizes the current pathophysiological roles of FSTL3, which may be a putative prognostic biomarker for various diseases and serve as a potential therapeutic target.

Mendelian randomization of circulating proteome identifies actionable targets in heart failure

Background

Heart failure (HF) is a prevalent cause of mortality and morbidity. The molecular drivers of HF are still largely unknown.

Results

We aimed to identify circulating proteins causally associated with HF by leveraging genome-wide genetic association data for HF including 47,309 cases and 930,014 controls. We performed two-sample Mendelian randomization (MR) with multiple cis instruments as well as network and enrichment analysis using data from blood protein quantitative trait loci (pQTL) (2,965 blood proteins) measured in 3,301 individuals. Nineteen blood proteins were causally associated with HF, were not subject to reverse causality and were enriched in ligand-receptor and glycosylation molecules. Network pathway analysis of the blood proteins showed enrichment in NF-kappa B, TGF beta, lipid in atherosclerosis and fluid shear stress. Cross-phenotype analysis of HF identified genetic overlap with cardiovascular drugs, myocardial infarction, parental longevity and low-density cholesterol. Multi-trait MR identified causal associations between HF-associated blood proteins and cardiovascular outcomes. Multivariable MR showed that association of BAG3, MIF and APOA5 with HF were mediated by the blood pressure and coronary artery disease. According to the directional effect and biological action, 7 blood proteins are targets of existing drugs or are tractable for the development of novel therapeutics. Among the pathways, sialyl Lewis x and the activin type II receptor are potential druggable candidates.

Conclusions

Integrative MR analyses of the blood proteins identified causally-associated proteins with HF and revealed pleiotropy of the blood proteome with cardiovascular risk factors. Some of the proteins or pathway related mechanisms could be targeted as novel treatment approach in HF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08811-2.

Endothelial Dysfunction in Heart Failure With Preserved Ejection Fraction: What are the Experimental Proofs?

Heart failure with preserved ejection fraction (HFpEF) has been recognized as the greatest single unmet need in cardiovascular medicine. Indeed, the morbi-mortality of HFpEF is high and as the population ages and the comorbidities increase, so considerably does the prevalence of HFpEF. However, HFpEF pathophysiology is still poorly understood and therapeutic targets are missing. An unifying, but untested, theory of the pathophysiology of HFpEF, proposed in 2013, suggests that cardiovascular risk factors lead to a systemic inflammation, which triggers endothelial cells (EC) and coronary microvascular dysfunction. This cardiac small vessel disease is proposed to be responsible for cardiac wall stiffening and diastolic dysfunction. This paradigm is based on the fact that microvascular dysfunction is highly prevalent in HFpEF patients. More specifically, HFpEF patients have been shown to have decreased cardiac microvascular density, systemic endothelial dysfunction and a lower mean coronary flow reserve. Importantly, impaired coronary microvascular function has been associated with the severity of HF. This review discusses evidence supporting the causal role of endothelial dysfunction in the pathophysiology of HFpEF in human and experimental models.

Inhibition of myostatin and related signaling pathways for the treatment of muscle atrophy in motor neuron diseases

Myostatin is a negative regulator of skeletal muscle growth secreted by skeletal myocytes. In the past years, myostatin inhibition sparked interest among the scientific community for its potential to enhance muscle growth and to reduce, or even prevent, muscle atrophy. These characteristics make it a promising target for the treatment of muscle atrophy in motor neuron diseases, namely, amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA), which are rare neurological diseases, whereby the degeneration of motor neurons leads to progressive muscle loss and paralysis. These diseases carry a huge burden of morbidity and mortality but, despite this unfavorable scenario, several therapeutic advancements have been made in the past years. Indeed, a number of different curative therapies for SMA have been approved, leading to a revolution in the life expectancy and outcomes of SMA patients. Similarly, tofersen, an antisense oligonucleotide, is now undergoing clinical trial phase for use in ALS patients carrying the SOD1 mutation. However, these therapies are not able to completely halt or reverse progression of muscle damage. Recently, a trial evaluating apitegromab, a myostatin inhibitor, in SMA patients was started, following positive results from preclinical studies. In this context, myostatin inhibition could represent a useful strategy to tackle motor symptoms in these patients. The aim of this review is to describe the myostatin pathway and its role in motor neuron diseases, and to summarize and critically discuss preclinical and clinical studies of myostatin inhibitors in SMA and ALS. Then, we will highlight promises and pitfalls related to the use of myostatin inhibitors in the human setting, to aid the scientific community in the development of future clinical trials.

Animal Models of Exercise From Rodents to Pythons

Acute and chronic animal models of exercise are commonly used in research. Acute exercise testing is used, often in combination with genetic, pharmacological, or other manipulations, to study the impact of these manipulations on the cardiovascular response to exercise and to detect impairments or improvements in cardiovascular function that may not be evident at rest. Chronic exercise conditioning models are used to study the cardiac phenotypic response to regular exercise training and as a platform for discovery of novel pathways mediating cardiovascular benefits conferred by exercise conditioning that could be exploited therapeutically. The cardiovascular benefits of exercise are well established, and, frequently, molecular manipulations that mimic the pathway changes induced by exercise recapitulate at least some of its benefits. This review discusses approaches for assessing cardiovascular function during an acute exercise challenge in rodents, as well as practical and conceptual considerations in the use of common rodent exercise conditioning models. The case for studying feeding in the Burmese python as a model for exercise-like physiological adaptation is also explored.