Sex-Related Differences in Protein Expression in Sarcomere Mutation-Positive Hypertrophic Cardiomyopathy

Characteristics and outcomes associated with sarcomere mutations in patients with hypertrophic cardiomyopathy: A systematic review and meta-analysis

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is an inherited heart disease that can lead to sudden cardiac death. Impact of genetic testing for the prognosis and treatment of patients with HCM needs to be improved. We conducted a systematic review and meta-analysis to investigate the characteristics and outcomes associated with sarcomere genotypes in index patients with HCM.

METHODS

A systematic search was conducted in Medline, Embase, and Cochrane Library up to Dec 31, 2023. Data on clinical characteristics, morphological and imaging features, outcomes and interventions were collected from published studies and pooled using a random-effects meta-analysis.

RESULTS

A total of 30 studies with 10,825 HCM index patients were included in the pooled analyses. The frequency of sarcomere genes in HCM patients was 41%. Sarcomere mutations were more frequent in women (p < 0.00001), and were associated with lower body mass index (26.1 ± 4.7 versus 27.5 ± 4.3; p = 0.003) and left ventricular ejection fraction (65.7% ± 10.1% vs. 67.1% ± 8.6%; p = 0.03), less apical hypertrophy (6.5% vs. 20.1%; p < 0.0001) and left ventricular outflow tract obstruction (29.1% vs. 33.2%; p = 0.03), greater left atrial volume index (43.6 ± 21.1 ml/m2 vs. 37.3 ± 13.0 ml/m2; p = 0.02). Higher risks of ventricular tachycardia (23.4% vs. 14.1%; p < 0.0001), syncope (18.3% vs. 10.9%; p = 0.01) and heart failure (17.3% vs. 14.6%; p = 0.002) were also associated with sarcomere mutations.

CONCLUSIONS

Sarcomere mutations are more frequent in women, and are associated with worse clinical characteristics and poor outcomes.

A Multi-Omics Atlas of Sex-Specific Differences in Obstructive Hypertrophic Cardiomyopathy

Background

Hypertrophic cardiomyopathy (HCM) is a common genetic heart disease. Women with HCM tend to have a later onset but more severe disease course. However, the underlying pathobiological mechanisms for these differences remain unknown.

Methods

Myectomy samples from 97 patients (53 males/44 females) with symptomatic obstructive HCM and 23 control cardiac tissues were included in this study. RNA-sequencing was performed on all samples. Mass spectrometry-based proteomics and phosphoproteomics was performed on a representative subset of samples.

Results

The transcriptome, proteome, and phosphoproteome was similar between sexes and did not separate on PCA plotting. Overall, there were 482 differentially expressed genes (DEGs) between control females and control males while there were only 53 DEGs between HCM females and HCM males. There were 1963 DEGs between HCM females and control females compared to 1064 DEGs between HCM males and control males. Additionally, there was increased transcriptional downregulation of hypertrophy pathways in HCM females and in HCM males. HCM females had 119 differentially expressed proteins compared to control females while HCM males only had 27 compared to control males. Finally, the phosphoproteome showed females had 341 differentially phosphorylated proteins (DPPs) compared to controls while males only had 184. Interestingly, there was hypophosphorylation and inactivation of hypertrophy pathways in females but hyperphosphorylation and activation in males.

Conclusion

There are subtle, but biologically relevant differences in the multi-omics profile of HCM. This study provides the most comprehensive atlas of sex-specific differences in the transcriptome, proteome, and phosphoproteome present at the time of surgical myectomy for obstructive HCM.

In need of age-appropriate cardiac models: Impact of cell age on extracellular matrix therapy outcomes

Aging is the main risk factor for cardiovascular disease (CVD). As the world's population ages rapidly and CVD rates rise, there is a growing need for physiologically relevant models of aging hearts to better understand cardiac aging. Translational research relies heavily on young animal models; however, these models correspond to early ages in human life, therefore cannot fully capture the pathophysiology of age-related CVD. Here, we first investigated the transcriptomic and proteomic changes that occur with human cardiac aging. We then chronologically aged human induced pluripotent stem cell-derived cardiomyocytes (iCMs) and showed that 14-month-old iCMs exhibited a similar aging profile to the human CMs and recapitulated age-related disease hallmarks. Using aged iCMs, we studied the effect of cell age on the young extracellular matrix (ECM) therapy, an emerging approach for myocardial infarction (MI) treatment and prevention. Young ECM decreased oxidative stress, improved survival, and post-MI beating in aged iCMs. In the absence of stress, young ECM improved beating and reversed aging-associated expressions in 3-month-old iCMs while causing the opposite effect on 14-month-old iCMs. The same young ECM treatment surprisingly increased SASP and impaired beating in advanced aged iCMs. Overall, we showed that young ECM therapy had a positive effect on post-MI recovery; however, cell age was determinant in the treatment outcomes without any stress conditions. Therefore, "one-size-fits-all" approaches to ECM treatments fail, and cardiac tissue engineered models with age-matched human iCMs are valuable in translational basic research for determining the appropriate treatment, particularly for the elderly.

Gender disparities in alcohol septal ablation for hypertrophic obstructive cardiomyopathy

OBJECTIVE

Alcohol septal ablation (ASA) improves symptoms in hypertrophic obstructive cardiomyopathy (HOCM). We conducted a large retrospective analysis investigating gender effects on outcome after ASA.

METHODS AND RESULTS

1367 ASAs between 2002 and 2020 were analysed. Women (47.2%) were older (66.0 years (IQR 55.0-74.0) vs 54.0 years (IQR 45.0-62.0); p<0.0001) with more severe symptoms. The interventricular septal diameter (IVSD) was higher in men (21.0 mm (IQR 19.0-24.0) vs 20.0 mm (IQR 18.0-23.0); p<0.0001) but the IVSD indexed to body surface area was higher in women (10.9 mm/m² (IQR 9.7-12.7) vs 10.2 mm/m² (IQR 9.0-11.7); p<0.0001). Women had lower exercise-induced left ventricular outflow tract gradients (LVOTG) 1-4 days after ASA (55.0 mm Hg (IQR 30.0-109.0) vs 71.0 mm Hg (IQR 37.0-115.0); p=0.0006). There was a trend for lower resting LVOTG 1-4 days after ASA (20.0 mm Hg (IQR 12.0-37.5) vs 22.0 mm Hg (IQR 13.0-40.0); p=0.0062) and lower exercise-induced LVOTG after 6 months in women (34.0 mm Hg (IQR 21.0-70.0) vs 43.5 mm Hg (IQR 25.0-74.8); p=0.0072), but this was not statistically significant after Bonferroni correction. More women developed atrioventricular (AV) block (20.3% vs 13.3%; p=0.0005) and required a pacemaker (17.4% vs 10.4%; p=0.0002) but not a cardioverter defibrillator (9.0% vs 11.6% in men; p=n .s.). However, in multivariable regression models, there was no evidence that sex independently influenced LVOTG and the occurrence of AV block.

CONCLUSION

Female patients with HOCM were older and had more advanced disease at the time of ASA. Women had superior short-term haemodynamic response to ASA but more often developed AV block after ASA. These results are important to consider for sex-specific counselling before ASA.

Defects in the Proteome and Metabolome in Human Hypertrophic Cardiomyopathy

BACKGROUND

Defects in energetics are thought to be central to the pathophysiology of hypertrophic cardiomyopathy (HCM); yet, the determinants of ATP availability are not known. The purpose of this study is to ascertain the nature and extent of metabolic reprogramming in human HCM, and its potential impact on contractile function.

METHODS

We conducted proteomic and targeted, quantitative metabolomic analyses on heart tissue from patients with HCM and from nonfailing control human hearts.

RESULTS

In the proteomic analysis, the greatest differences observed in HCM samples compared with controls were increased abundances of extracellular matrix and intermediate filament proteins and decreased abundances of muscle creatine kinase and mitochondrial proteins involved in fatty acid oxidation. These differences in protein abundance were coupled with marked reductions in acyl carnitines, byproducts of fatty acid oxidation, in HCM samples. Conversely, the ketone body 3-hydroxybutyrate, branched chain amino acids, and their breakdown products, were all significantly increased in HCM hearts. ATP content, phosphocreatine, nicotinamide adenine dinucleotide and its phosphate derivatives, NADP and NADPH, and acetyl CoA were also severely reduced in HCM compared with control hearts. Functional assays performed on human skinned myocardial fibers demonstrated that the magnitude of observed reduction in ATP content in the HCM samples would be expected to decrease the rate of cross-bridge detachment. Moreover, left atrial size, an indicator of diastolic compliance, was inversely correlated with ATP content in hearts from patients with HCM.

CONCLUSIONS

HCM hearts display profound deficits in nucleotide availability with markedly reduced capacity for fatty acid oxidation and increases in ketone bodies and branched chain amino acids. These results have important therapeutic implications for the future design of metabolic modulators to treat HCM.

Sex-Related Differences in Genetic Cardiomyopathies

Cardiomyopathies are a heterogeneous collection of diseases that have in common primary functional and structural abnormalities of the heart muscle, often genetically determined. The most effective categorization of cardiomyopathies is based on the presenting phenotype, with hypertrophic, dilated, arrhythmogenic, and restrictive cardiomyopathy as the prototypes. Sex modulates the prevalence, morpho-functional manifestations and clinical course of cardiomyopathies. Aspects as diverse as ion channel expression and left ventricular remodeling differ in male and female patients with myocardial disease, although the reasons for this are poorly understood. Moreover, clinical differences may also result from complex societal/environmental discrepancies between sexes that may disadvantage women. This review provides a state-of-the-art appraisal of the influence of sex on cardiomyopathies, highlighting the many gaps in knowledge and open research questions.

Genetic, Molecular, and Cellular Determinants of Sex-Specific Cardiovascular Traits

Despite the well-known sex dimorphism in cardiovascular disease traits, the exact genetic, molecular, and cellular underpinnings of these differences are not well understood. A growing body of evidence currently points at the links between cardiovascular disease traits and the genome, epigenome, transcriptome, and metabolome. However, the sex-specific differences in these links remain largely unstudied due to challenges in bioinformatic methods, inadequate statistical power, analytic costs, and paucity of valid experimental models. This review article provides an overview of the literature on sex differences in genetic architecture, heritability, epigenetic changes, transcriptomic signatures, and metabolomic profiles in relation to cardiovascular disease traits. We also review the literature on the associations between sex hormones and cardiovascular disease traits and discuss the potential mechanisms underlying these associations, focusing on human studies.