Sex differences in the response to angiotensin II receptor blockade in a rat model of eccentric cardiac hypertrophy

Sex-based differences in left ventricular mass reduction across angiotensin II receptor blockers in patients with heart failure with preserved or mildly reduced ejection fraction

Although angiotensin II receptor blockers (ARBs) are more effective in women for either reduction of blood pressure or heart failure (HF), the gender disparities and the impact of class/drug effects on ARBs in relation to cardiac hypertrophy and HF remain unclear. We aimed to investigate the sex-based and drug-specific differences in left ventricular (LV) mass reduction with ARBs. We employed the cohort of 193 hypertensive patients with HF and an LV ejection fraction of ≥ 45% treated with azilsartan or candesartan once daily for 48 weeks as a sub-analysis of the J-TASTE trial. After exclusion of patients without LV mass data nor the drugs, 170 patients were finally enrolled (azilsartan: male, n = 43, female, n = 39 and candesartan: male, n = 52; female, n = 36). We investigated the sex-based differences of the primary endpoint of the change in LV mass as assessed by echocardiography from baseline to the end of the study (48 weeks), and the secondary endpoint of the incidence of the composite cardiovascular endpoint (death from cardiovascular disease or hospitalization for heart failure). In the male stratum, the ratio of patients with > 10% LV mass reduction at 48 weeks was higher in the azilsartan group than candesartan group (40 vs. 19%, p = 0.029). There was no significant difference in LV mass reduction between two groups in the female stratum. There were no differences of the onset of the secondary endpoints between male and female groups, and azilsartan and candesartan groups. The event-free survival rate of the composite cardiovascular endpoints tended to be lower in patients with ≤ 10% than > 10% LV mass reduction (95.3 vs. 100% at 48 weeks, log-rank p = 0.11). In patients with HF, the effectiveness of either azilsartan or candesartan in achieving > 10% LV mass reduction depends on sex. Male is more sensitive to azilsartan than candesartan to achieve cardiac hypertrophy in HF patients.

Therapeutic targets of fibrosis: Translational advances and current challenges

In a physiological context, the extracellular matrix (ECM) provides an important scaffold for organs. Dysregulation of ECM in disease conditions, characterised by excess deposition of connective tissue and extracellular matrix in response to a pathological insult, is a key driver of disease progression in multiple organs. The resultant fibrosis is predominantly an irreversible process and directly contributes to, and exacerbates, dysfunction of an affected organ. This is particularly paramount in the kidney, liver, heart and lung. A hybrid Joint Meeting of NC-IUPHAR and British Pharmacological Society was held in Paris and via a webinar in November 2020, when two successive sessions were devoted to translational advances in fibrosis as a therapeutic target. On the upsurge of response to these sessions, the concept of a special themed issue on this topic emerged, and is entitled Translational Advances in Fibrosis as a Therapeutic Target. In this special issue, we seek to provide an up-to-date account of the diverse molecular mechanisms and causal role that fibrosis plays in disease progression (contributing to, and exacerbating, dysfunction of affected organs). Recent developments in the understanding of molecular targets involved in fibrosis, and how their actions can be manipulated therapeutically, are included. LINKED ARTICLES: This article is part of a themed issue on Translational Advances in Fibrosis as a Therapeutic Target. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.22/issuetoc.

Current challenges in the treatment of cardiac fibrosis: Recent insights into the sex-specific differences of glucose-lowering therapies on the diabetic heart: IUPHAR Review 33

A significant cardiac complication of diabetes is cardiomyopathy, a form of ventricular dysfunction that develops independently of coronary artery disease, hypertension and valvular diseases, which may subsequently lead to heart failure. Several structural features underlie the development of diabetic cardiomyopathy and eventual diabetes-induced heart failure. Pathological cardiac fibrosis (interstitial and perivascular), in addition to capillary rarefaction and myocardial apoptosis, are particularly noteworthy. Sex differences in the incidence, development and presentation of diabetes, heart failure and interstitial myocardial fibrosis have been identified. Nevertheless, therapeutics specifically targeting diabetes-associated cardiac fibrosis remain lacking and treatment approaches remain the same regardless of patient sex or the co-morbidities that patients may present. This review addresses the observed anti-fibrotic effects of newer glucose-lowering therapies and traditional cardiovascular disease treatments, in the diabetic myocardium (from both preclinical and clinical contexts). Furthermore, any known sex differences in these treatment effects are also explored. LINKED ARTICLES: This article is part of a themed issue on Translational Advances in Fibrosis as a Therapeutic Target. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.22/issuetoc.

Sex differences in myocardial remodeling and extracellular volume in aortic regurgitation

Whether sex differences exist in the cardiac remodeling related to aortic regurgitation (AR) is unclear. Cardiac magnetic resonance (CMR) is the current non-invasive reference standard for cardiac remodeling assessment and can evaluate tissue characteristics. This prospective cohort included patients with AR undergoing CMR between 2011 and 2020. We excluded patients with confounding causes of remodeling. We quantified left ventricular (LV) volume, mass, AR severity, replacement fibrosis by late Gadolinium enhancement (LGE), and extracellular expansion by extracellular volume fraction (ECV). We studied 280 patients (109 women), median age 59.5 (47.2, 68.6) years (P for age = 0.25 between sexes). Women had smaller absolute LV volume and mass than men across the spectrum of regurgitation volume (RVol) (P ≤ 0.01). In patients with ≥ moderate AR and with adjustment for body surface area, indexed LV end-diastolic volume and mass were not significantly different between sexes (all P > 0.5) but men had larger indexed LV end systolic volume and lower LV ejection fraction (P ≥ 0.01). Women were more likely to have NYHA class II or greater symptoms than men but underwent surgery at a similar rate. Prevalence and extent of LGE was not significantly different between sexes or across RVol. Increasing RVol was independently associated with increasing ECV in women, but not in men (adjusted P for interaction = 0.03). In conclusion, women had lower LV volumes and mass than men across AR severity  but their ECV increased with higher regurgitant volume, while ECV did not change in men. Indexing to body surface area did not fully correct for the cardiac remodeling differences between men and women. Women were more likely to have symptoms but underwent surgery at a similar rate to men. Further research is needed to determine if differences in ECV would translate to differences in the course of AR and outcomes.

Puerarin attenuates isoproterenol‑induced myocardial hypertrophy via inhibition of the Wnt/β‑catenin signaling pathway

Myocardial hypertrophy (MH) is an independent risk factor for cardiovascular disease, which in turn lead to arrhythmia or heart failure. Therefore, attention must be paid to formulation of therapeutic strategies for MH. Puerarin is a key bioactive ingredient isolated from Pueraria genera of plants that is beneficial for the treatment of MH. However, its molecular mechanism of action has not been fully determined. In the present study, 40 µM puerarin was demonstrated to be a safe dose for human AC16 cells using Cell Counting Kit‑8 assay. The protective effects of puerarin against MH were demonstrated in AC16 cells stimulated with isoproterenol (ISO). These effects were characterized by a significant decrease in surface area of cells (assessed using fluorescence staining) and mRNA and protein expression levels of MH‑associated biomarkers, including atrial and brain natriuretic peptide, assessed using reverse transcription‑quantitative PCR and western blotting, as well as β‑myosin heavy chain mRNA expression levels. Mechanistically, western blotting demonstrated that puerarin inhibited activation of the Wnt signaling pathway. Puerarin also significantly decreased phosphorylation of p65; this was mediated via crosstalk between the Wnt and NF‑κB signaling pathways. An inhibitor (Dickkopf‑1) and activator (IM‑12) of the Wnt signaling pathway were used to demonstrate that puerarin‑mediated effects alleviated ISO‑induced MH via the Wnt signaling pathway. The results of the present study demonstrated that puerarin pre‑treatment may be a potential therapeutic strategy for preventing ISO‑induced MH and managing MH in the future.

Sex differences in the evolution of left ventricle remodeling in rats with severe volume overload

Background

Aortic valve regurgitation (AR) results in left ventricle (LV) volume overload (VO) leading to its dilation and hypertrophy (H). We study a rat model of severe AR induced by puncturing one or two leaflets using a catheter. Most of our studies were conducted in male animals. Recently, we started investigating if sex dimorphism existed in the AR rat model. We observed that AR females developed as much LVH as males but morphological remodeling differences were present. A head-to-head comparison of LV morphological and functional changes had never been performed in AR males (M) and females (F) using the latest modalities in cardiac imaging by echocardiography.

Methods

We performed a longitudinal study to evaluate the development of LV hypertrophy caused by chronic AR in male and female rats over 6 months. Sham-operated (sham) animals were used as controls.

Results

LV diastolic volumes (EDV) increased more over 6 months in sham males than in females (38% vs. 23% for EDV, both p < 0.01). AR resulted in significant LV dilation for both sexes (54% vs. 51% increase in EDV) vs. baseline values. Since normal cardiac growth was less in females, dilation from AR was relatively more important for them (88% (M) vs. 157% (F) increase in EDV over sham). AR caused LV wall thickening in both males and females. It happened sooner for AR females and was more important than in males (25% (M) vs. 56% (F) increase in septum thickness at 2 months and 10% (M) vs. 30% (F) at 6 months). We then evaluated if AR was associated with changes in LV strain using speckle-tracking 2D echocardiography. Global longitudinal strain remained similar between AR and sham animals. Circumferential strain was negatively modulated by AR but only in females and early after VO induction (13% (M) vs. 26% (F)).

Conclusion

AR resulted in more LV dilation and quicker wall thickening in female AR rats compared to males. Global circumferential strain was negatively modulated in AR females but not in males. AR also seemed to lead to a more spherical LV shape in females whereas; it kept mostly an ellipsoid shape in males. This can influence validity of mass estimation of the dilated LV in females by echocardiography.