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

Therapeutic potential of relaxin or relaxin mimetics in managing cardiovascular complications of diabetes

Diabetes mellitus is a metabolic disease with an escalating global prevalence. Despite the abundance and relative efficacies of current therapeutic approaches, they primarily focus on attaining the intended glycaemic targets, but patients ultimately still suffer from various diabetes-associated complications such as retinopathy, nephropathy, cardiomyopathy, and atherosclerosis. There is a need to explore innovative and effective diabetic treatment strategies that not only address the condition itself but also combat its complications. One promising option is the reproductive hormone relaxin, an endogenous ligand of the RXFP1 receptor. Relaxin is known to exert beneficial actions on the cardiovascular system through its vasoprotective, anti-inflammatory and anti-fibrotic effects. Nevertheless, the native relaxin peptide exhibits a short biological half-life, limiting its therapeutic potential. Recently, several relaxin mimetics and innovative delivery technologies have been developed to extend its biological half-life and efficacy. The current review provides a comprehensive landscape of the cardiovascular effects of relaxin, focusing on its potential therapeutic applications in managing complications associated with diabetes. The latest advancements in the development of relaxin mimetics and delivery methods for the treatment of cardiometabolic disorders are also discussed.

Exogenous ECM in an environmentally-mediated in vitro model for cardiac fibrosis

Few clinical solutions exist for cardiac fibrosis, creating the need for a tunable in vitro model to better understand fibrotic disease mechanisms and screen potential therapeutic compounds. Here, we combined cardiomyocytes, cardiac fibroblasts, and exogenous extracellular matrix (ECM) proteins to create an environmentally-mediated in vitro cardiac fibrosis model. Cells and ECM were combined into 2 types of cardiac tissues- aggregates and tissue rings. The addition of collagen I had a drastic negative impact on aggregate formation, but ring formation was not as drastically affected. In both tissue types, collagen and other ECM did not severely affect contractile function. Histological analysis showed direct incorporation of collagen into tissues, indicating that we can directly modulate the cells' ECM environment. This modulation affects tissue formation and distribution of cells, indicating that this model provides a useful platform for understanding how cells respond to changes in their extracellular environment and for potential therapeutic screening.

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.

Cardiac Fibrosis in heart failure: Focus on non-invasive diagnosis and emerging therapeutic strategies

Heart failure is a leading cause of mortality and hospitalization worldwide. Cardiac fibrosis, resulting from the excessive deposition of collagen fibers, is a common feature across the spectrum of conditions converging in heart failure. Eventually, either reparative or reactive in nature, in the long-term cardiac fibrosis contributes to heart failure development and progression and is associated with poor clinical outcomes. Despite this, specific cardiac antifibrotic therapies are lacking, making cardiac fibrosis an urgent unmet medical need. In this context, a better patient phenotyping is needed to characterize the heterogenous features of cardiac fibrosis to advance toward its personalized management. In this review, we will describe the different phenotypes associated with cardiac fibrosis in heart failure and we will focus on the potential usefulness of imaging techniques and circulating biomarkers for the non-invasive characterization and phenotyping of this condition and for tracking its clinical impact. We will also recapitulate the cardiac antifibrotic effects of existing heart failure and non-heart failure drugs and we will discuss potential strategies under preclinical development targeting the activation of cardiac fibroblasts at different levels, as well as targeting additional extracardiac processes.

YuNü-Jian attenuates diabetes-induced cardiomyopathy: integrating network pharmacology and experimental validation

Introduction

Diabetic cardiomyopathy (DCM) is one of the most prevalent complications of diabetes with complex pathogenesis. YuNü-Jian (YNJ) is a traditional Chinese medicinal formula widely used for diabetes with hypoglycemic and cardioprotective effects. This study aims to investigate the actions and mechanisms of YNJ against DCM which has never been reported.

Methods

Network pharmacology approach was used to predict the potential pathways and targets of YNJ on DCM. Molecular docking between hub targets and active components of YNJ was performed and visualized by AutoDock Vina and PyMOL. Then type 2 diabetic model was employed and intervened with YNJ for 10 weeks to further validate these critical targets.

Results

First, a total of 32 main ingredients of YNJ were identified and 700 potential targets were screened to construct herb-compound-target network. Then 94 differentially expressed genes of DCM were identified from GEO database. After that, PPI network of DCM and YNJ were generated from which hub genes (SIRT1, Nrf2, NQO1, MYC and APP) were assessed by topology analysis. Next, functional and pathway analysis indicated that the candidate targets were enriched in response to oxidative stress and Nrf2 signaling pathway. Furthermore, molecular docking revealed strong affinity between core targets and active components of YNJ. Finally, in rats with type 2 diabetes, YNJ obviously attenuated cardiac collagen accumulation and degree of fibrosis. Meanwhile, YNJ significantly upregulated protein expression of SIRT1, Nrf2 and NQO1 in diabetic myocardium.

Discussion

Collectively, our findings suggested that YNJ could effectively ameliorate cardiomyopathy induced by diabetes possibly through SIRT1/Nrf2/NQO1 signaling.

Sex differences in risk of cardiovascular events and mortality with sodium glucose co-transporter-2 inhibitors versus glucagon-like peptide 1 receptor agonists in Australians with type 2 diabetes: a population-based cohort study

Background

Sodium glucose co-transporter-2 inhibitors (SGLT2i) and glucagon-like peptide 1 receptor agonists (GLP-1RAs) reduce major adverse cardiovascular events (MACE) in people with type 2 diabetes (T2D). Despite known sex differences in diabetes-induced cardiovascular disease (CVD), pharmacological treatment recommendations are independent of sex. Our objective was to investigate possible sex differences in rates of MACE with SGLT2i vs. GLP-1RA use.

Methods

This population-based cohort study included men and women with T2D (≥30 years), discharged from a Victorian hospital between 1st July 2013 and 1st July 2017, and dispensed an SGLT2i or GLP-1RA within 60 days of discharge. Using Cox proportional hazards regression with competing risks, subdistribution hazard ratios (sHR) with 95% confidence intervals (CI) were estimated for MACE in a follow-up to 30th June 2018. Analyses were conducted for men and women, and subgroups based on age, baseline heart failure (HF), and atherosclerotic CVD (ASCVD) status.

Findings

From a total of 8026 people (44.3% women, median follow-up time = 756 days), SGLT2i (n = 4231), compared to GLP-1RAs (n = 3795), reduced MACE rates in men (sHR 0.78; 95%CI 0.66-0.93), but not women. SGLT2i reduced MACE rates in men (sHR 0.72; 95%CI 0.54-0.98) and women (sHR 0.52; 95%CI 0.31-0.86) ≥65 years; in men with baseline HF (sHR 0.45; 95%CI 0.28-0.73); and in women with ASCVD (sHR 0.36; 95%CI 0.18-0.71).

Interpretations

SGLT2i, relative to GLP-1RAs, demonstrate favourable effects for MACE reductions among older Australian men and women with T2D. Analogous benefits were also observed in men with HF and women with ASCVD.

Funding

Dementia Australia Yulgilbar Innovation Award.

A high-sucrose diet exacerbates the left ventricular phenotype in a high fat-fed streptozotocin rat model of diabetic cardiomyopathy

Left ventricular (LV) dysfunction is an early, clinically detectable sign of cardiomyopathy in type 2 diabetes mellitus (T2DM) that precedes the development of symptomatic heart failure. Preclinical models of diabetic cardiomyopathy are essential to develop therapies that may prevent or delay the progression of heart failure. This study examined the molecular, structural, and functional cardiac phenotype of two rat models of T2DM induced by a high-fat diet (HFD) with a moderate- or high-sucrose content (containing 88.9 or 346 g/kg sucrose, respectively), plus administration of low-dose streptozotocin (STZ). At 8 wk of age, male Sprague-Dawley rats commenced a moderate- or high-sucrose HFD. Two weeks later, rats received low-dose STZ (35 mg/kg ip for 2 days) and remained on their respective diets. LV function was assessed by echocardiography 1 wk before end point. At 22 wk of age, blood and tissues were collected postmortem. Relative to chow-fed sham rats, diabetic rats on a moderate- or high-sucrose HFD displayed cardiac reactive oxygen species dysregulation, perivascular fibrosis, and impaired LV diastolic function. The diabetes-induced impact on LV adverse remodeling and diastolic dysfunction was more apparent when a high-sucrose HFD was superimposed on STZ. In conclusion, a high-sucrose HFD in combination with low-dose STZ produced a cardiac phenotype that more closely resembled T2DM-induced cardiomyopathy than STZ diabetic rats subjected to a moderate-sucrose HFD.NEW & NOTEWORTHY Left ventricular dysfunction and adverse remodeling were more pronounced in diabetic rats that received low-dose streptozotocin (STZ) and a high-sucrose high-fat diet (HFD) compared with those on a moderate-sucrose HFD in combination with STZ. Our findings highlight the importance of sucrose content in diet composition, particularly in preclinical studies of diabetic cardiomyopathy, and demonstrate that low-dose STZ combined with a high-sucrose HFD is an appropriate rodent model of cardiomyopathy in type 2 diabetes.

Aryl hydrocarbon receptor: From pathogenesis to therapeutic targets in aging-related tissue fibrosis

Aging promotes chronic inflammation, which contributes to fibrosis and decreases organ function. Fibrosis, the excessive synthesis and deposition of extracellular matrix components, is the main cause of most chronic diseases including aging-related organ failure. Organ fibrosis in the heart, liver, and kidneys is the final manifestation of many chronic diseases. The aryl hydrocarbon receptor (AHR) is a cytoplasmic receptor and highly conserved transcription factor that is activated by a variety of small-molecule ligands to affect a wide array of tissue homeostasis functions. In recent years, mounting evidence has revealed that AHR plays an important role in multi-organ fibrosis initiation, progression, and therapy. In this review, we summarise the relationship between AHR and the pathogenesis of aging-related tissue fibrosis, and further discuss how AHR modulates tissue fibrosis by regulating transforming growth factor-β signalling, immune response, and mitochondrial function, which may offer novel targets for the prevention and treatment of this condition.