Inhibition of HMOX1 alleviates diabetic cardiomyopathy by targeting ferroptosis

Abstract

Diabetic cardiomyopathy (DCM) is an important complication of chronic diabetes mellitus. However, its pathologic process and pathogenesis have not been fully elucidated. This study aims to investigate the role of ferroptosis in DCM and clarify the effect of heme oxygenase-1 (HMOX1) on DCM by targeting ferroptosis. In vivo, an animal model of DCM is established by subjecting mice to a high-fat diet (HFD) combined with low-dose streptozotocin (STZ) injection. We induce an in vitro DCM model by exposing H9C2 cells to high glucose and palmitic acid. Transcriptome sequencing reveals that the differentially expressed genes (DEGs) are enriched primarily in fatty acid metabolism and mitochondrial fatty acid β-oxidation, which are closely related to ferroptosis. The experimental results show that the diabetic microenvironment induces ferroptosis both in vivo and in vitro. Western blot analysis reveals the decreased expressions of the antioxidant proteins GPX4, SLC7A11 and ferritin in the DCM group. However, qPCR demonstrates the elevated expressions of the ferroptosis markers PTGS2 and ACSL4. Biochemical indicators further support the occurrence of ferroptosis, with increased levels of malondialdehyde (MDA) and lactate dehydrogenase (LDH), along with decreased level of glutathione (GSH). In vitro, intervention with high glucose and palmitic acid in H9C2 cells results in ferroptosis, which is reversed by ferrostatin-1 (Fer-1). Results show the elevated expression of HMOX1 in DCM. Moreover, knockdown of HMOX1 ameliorates ferroptosis, thereby alleviating diabetic cardiomyopathy by reducing cardiac fibrosis and improving cardiac function. Our study elucidates the role of HMXO1 in DCM pathogenesis and provides a potential therapeutic strategy for clinical treatment.

1. Introduction

Over the past few decades, diabetes mellitus (DM) has emerged as a global epidemic due to lifestyle changes, technological advancements and social development [1]. DM is recognized as an independent risk factor for cardiovascular diseases across different ethnic groups and sexes [2]. Type 2 diabetes is characterized by metabolic disorders, such as obesity and insulin resistance, leading to abnormal glucose and dyslipidemia in various organs, including the heart [3]. Diabetic cardiomyopathy (DCM) is a primary myocardial injury induced by DM in the absence of coronary artery disease, hypertension, dyslipidemia and valvular heart disease [4]. DCM has a complex pathogenesis, initially manifesting as diastolic relaxation abnormalities and progressing to clinical heart failure [5]. However, the underlying pathophysiological mechanisms of DCM are not yet fully understood. Currently, DCM treatment focuses on controlling blood glucose, blood pressure, and lipid levels and improving lifestyle. Specific targeted treatment methods are not yet available, and the incidence and mortality rates of heart failure remain high.

Ferroptosis, which was first defined by Dr. Brent R Stockwell in 2012 [6], represents a unique form of cell death driven by iron-dependent phospholipid peroxidation [7]. It is characterized by the inactivation of cellular glutathione (GSH), depletion of glutathione peroxidase 4 (GPX4), and accumulation of toxic lipid-reactive oxygen species (ROS) [8]. Ferroptosis has been implicated in various types of pathological cell death associated with carcinogenesis, stroke, degenerative diseases, ischaemia‒reperfusion injury, and kidney degeneration [9]. In recent years, the role of ferroptosis in cardiovascular diseases (CVDs) has been highlighted, suggesting its potential as a therapeutic target for CVD [10]. Emerging evidence indicates the involvement of ferroptosis in diabetic complications due to cellular metabolic disorders [11]. However, the association between ferroptosis and DCM has not been extensively explored [12].