Abstract 4341368: Hepatic Retinol-Binding Protein 4 Mediates the Exacerbation of Myocardial I/R Injury in MAFLD mice through Augmented Oxidative Stress and Ferroptosis

Background: Metabolic dysfunction-associated fatty liver disease (MAFLD), with a global prevalence of 25%, is increasingly linked to heightened coronary artery disease (CAD) risk, accelerated CAD progression, and adverse cardiovascular outcomes. Notably, MAFLD-comorbid CAD patients exhibit worse reperfusion outcomes compared to those with healthy livers, highlighting the need to elucidate the mechanisms by which MAFLD exacerbates cardiac ischemia/reperfusion (I/R) injury. Methods: Using a 12-week high-fat, high-fructose, high-cholesterol diet (GAN diet)-induced MAFLD model and 45-minute left anterior descending artery ligation (LAD)-induced I/R model, we performed proteomic analysis of liver and serum 3 day post-I/R. Normal chow (healthy liver) or sham (non-I/R) was used as control. Ferroptosis was assessed by measuring the levels of Malondialdehyde (MDA) and ferroptosis-related proteins. Results: The mice with both MAFLD and I/R had a significantly worse cardiac performance according to the echocardiography and fibrosis (Fig 1A-D). Further investigations revealed the most pronounced cardiac oxidative stress and ferroptosis in the MAFLD+I/R mice (Fig 1E-G). Among the differentially expressed proteins, Retinol-binding protein 4 (RBP4), a lipocalin family member, was significantly upregulated in the liver (fold change, 2.149, p <0.0001) and serum (fold change, 1.460, p =0.0246) of MAFLD+I/R versus Chow+I/R mice (Fig 2A). As shown in western blot and enzyme-linked immunosorbent assay, although local RBP4 increased post-I/R, its levels were highest in MAFLD+I/R mice in serum and heart (Fig 2B-D). Pharmacological inhibition of RBP4 blood transport with A1120 attenuated cardiac RBP4 accumulation without affecting local RBP4 production (Fig 3A,B). Consistently, the myocardial oxidative stress and ferroptosis (Fig 3C,D) and I/R injury (Fig 3E-H) in MAFLD+I/R mice were alleviated by A1120 to levels similar to the Chow+I/R group. Conclusions: Our findings identify hepatic RBP4 as a key mediator of liver-heart crosstalk, synergizing with locally produced RBP4 to drive oxidative stress and ferroptosis in I/R injury. These results provide mechanistic insights into the adverse impact of MAFLD on cardiac I/R outcomes and highlight RBP4 as a potential therapeutic target.