Ketone bodies in right ventricular failure: A unique therapeutic opportunity

Emerging roles of ketone bodies in cardiac fibrosis

Cardiac fibrosis, characterized by excessive extracellular matrix (ECM) deposition within the myocardium, poses a significant challenge in cardiovascular health, contributing to various cardiac pathologies. Ketone bodies (KBs), particularly β-hydroxybutyrate (β-OHB), have emerged as subjects of interest due to their potential cardioprotective effects. However, their specific influence on cardiac fibrosis remains underexplored. This literature review comprehensively examines the relationship between KBs and cardiac fibrosis, elucidating potential mechanisms through which KBs modulate fibrotic pathways. A multifaceted interplay exists between KBs and key mediators of cardiac fibrosis. While some studies indicate a profibrotic role for KBs, others highlight their potential to attenuate fibrosis and cardiac remodeling. Mechanistically, KBs may regulate fibrotic pathways through modulation of cellular components such as cardiac fibroblasts, macrophages, and lymphocytes, as well as extracellular matrix proteins. Furthermore, the impact of KBs on cellular processes implicated in fibrosis, including oxidative stress, chemokine and cytokine expression, caspase activation, and inflammasome signaling is explored. While conflicting findings exist regarding the effects of KBs on these processes, emerging evidence suggests a predominantly beneficial role in mitigating inflammation and oxidative stress associated with fibrotic remodeling. Overall, this review underscores the importance of elucidating the complex interplay between KB metabolism and cardiac fibrosis. The insights gained have the potential to inform novel therapeutic strategies for managing cardiac fibrosis and associated cardiovascular disorders, highlighting the need for further research in this area.

Extrapulmonary manifestations of pulmonary arterial hypertension

INTRODUCTION

Extrapulmonary manifestations of pulmonary arterial hypertension (PAH) may play a critical pathobiological role and a deeper understanding will advance insight into mechanisms and novel therapeutic targets. This manuscript reviews our understanding of extrapulmonary manifestations of PAH.

AREAS COVERED

A group of experts was assembled and a complimentary PubMed search performed (October 2023 - March 2024). Inflammation is observed throughout the central nervous system and attempts at manipulation are an encouraging step toward novel therapeutics. Retinal vascular imaging holds promise as a noninvasive method of detecting early disease and monitoring treatment responses. PAH patients have gut flora alterations and dysbiosis likely plays a role in systemic inflammation. Despite inconsistent observations, the roles of obesity, insulin resistance and dysregulated metabolism may be illuminated by deep phenotyping of body composition. Skeletal muscle dysfunction is perpetuated by metabolic dysfunction, inflammation, and hypoperfusion, but exercise training shows benefit. Renal, hepatic, and bone marrow abnormalities are observed in PAH and may represent both end-organ damage and disease modifiers.

EXPERT OPINION

Insights into systemic manifestations of PAH will illuminate disease mechanisms and novel therapeutic targets. Additional study is needed to understand whether extrapulmonary manifestations are a cause or effect of PAH and how manipulation may affect outcomes.

The therapeutic potential of ketones in cardiometabolic disease: impact on heart and skeletal muscle

β-Hydroxybutyrate (βOHB) is the major ketone in the body, and it is recognized as a metabolic energy source and an important signaling molecule. While ketone oxidation is essential in the brain during prolonged fasting/starvation, other organs such as skeletal muscle and the heart also use ketones as metabolic substrates. Additionally, βOHB-mediated molecular signaling events occur in heart and skeletal muscle cells, and via metabolism and/or signaling, ketones may contribute to optimal skeletal muscle health and cardiac function. Of importance, when the use of ketones for ATP production and/or as signaling molecules becomes disturbed in the presence of underlying obesity, type 2 diabetes, and/or cardiovascular diseases, these changes may contribute to cardiometabolic disease. As a result of these disturbances in cardiometabolic disease, multiple approaches have been used to elevate circulating ketones with the goal of optimizing either ketone metabolism or ketone-mediated signaling. These approaches have produced significant improvements in heart and skeletal muscle during cardiometabolic disease with a wide range of benefits that include improved metabolism, weight loss, better glycemic control, improved cardiac and vascular function, as well as reduced inflammation and oxidative stress. Herein, we present the evidence that indicates that ketone therapy could be used as an approach to help treat cardiometabolic diseases by targeting cardiac and skeletal muscles.