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Background Acute myocardial infarction (MI) causes significant changes in cardiac morphology and function. Galectin-3 is a novel and potentially therapeutically important mediator of cardiac remodelling. Myocardial and serum galectin-3 expression dynamics in response to the early cardiovascular outcomes after acute MI are not fully elucidated. Methods We first performed a comprehensive longitudinal microarray analyses in mice after acute MI. We then measured the serum levels of galectin-3 in a translational porcine model of coronary microembolism-induced post-ischaemic cardiac remodelling. We validated our pre-clinical studies in humans by measuring serum galectin-3 levels of 52 patients with acute ST-elevation MI (STEMI) and 11 healthy controls. We analysed galectin-3 data in relation to the development of major adverse cardiovascular outcomes (MACO). Results Of the 9,753 genes profiled at infarcted and remote myocardium at eight different time points, dynamic myocardial overexpression of galectin-3 mRNA was detected. In a pig model of diffuse myocardial damage and cardiac remodelling, galectin-3 localised to the areas of tissue damage and myocardial fibrosis, with proportionate increase of their serum galectin-3 expression levels. In humans, increased serum galectin-3 level was associated with in-hospital MACO. Conclusions In this translational study, we demonstrated that galectin-3 is dynamically overexpressed in response to acute MI-induced cardiac remodelling. Elevated galectin-3 levels are associated with the development of in-hospital MACO.

Introduction:Increased galectin-3 is associated with ischemic cardiomyopathy, although its role in early remodeling post-myocardial infarction (MI) has not been fully elucidated. There are no data demonstrating that blocking galectin-3 expression would have an impact on the heart and that its relationship to remodeling is not simply an epiphenomenon. The direct association between galectin-3 and myocardial inflammation, dysfunction, and adverse cardiovascular outcomes post-MI was examined using clinical and translational studies.Methods:We performed expression analysis of 9753 genes in murine model of acute MI. For galectin-3 loss of function studies, homozygous galectin-3 knock-out (KO) mice were subjected to coronary artery ligation procedure to induce acute MI (MI, N = 6; Sham, N = 6). For clinical validation, serum galectin-3 levels were measured in 96 patients with ST-elevation MI. Echocardiographic and angiographic parameters of myocardial dysfunction and 3-month composite outcome including mortality, recurrent MI, stroke, and heart failure hospitalization were measured.Results:In the infarct regions of murine models, galectin-3 was a robustly expressed gene. Elevated galectin-3 expression strongly correlated with macrophage-mediated genes. Galectin-3 KO mice showed reduced myocardial macrophage infiltration after acute MI. Galectin-3 levels were higher in patients with early systolic dysfunction, and predicted 3-month major adverse cardiovascular events (area under the curve [AUC]: 0.917 ± 0.063; P = .001).Conclusions:Galectin-3 is directly associated with early myocardial inflammation post-MI and may represent a potential target for therapeutic inhibition.

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Duchenne muscular dystrophy (DMD) is a fatal disease where over 90% of patients succumb to respiratory or cardiac failure. Sleep apnea and sleep disordered breathing (SDB) are noted in a plurality of DMD patients, and the resulting nocturnal episodic hypoxia (EH) cannot be ruled out as a contributing factor to cardiac and respiratory dysfunction. In this study, we investigated the impact of long-term episodic hypoxia, which mimics the cyclic hypoxia seen in sleep apnea, on cardiac and respiratory function in a murine model of DMD (mdx mice). Since the severity and prevalence of sleep apnea in DMD increases with age, we studied the impact of EH on young (6-month) and on older (18-month) mdx mice. Mice were either exposed for 12 weeks to EH (8 hours/day, 5 days/week) or to room air. We noted a significant increase in left ventricular (LV) dilatation (transthoracic echocardiography) on EH exposure in both age groups, but reduced LV contractility was seen only in 6-month old mice. With EH exposure, an increased fibrosis (hydroxyproline) was noted in both cardiac and diaphragm muscle in 18-month but not 6-month old mice. No significant change in relative diaphragm strength (in-vitro) was noted on EH exposure in 18-month old mice. In contrast, EH exposed 6-month old mice showed a significant increase in relative diaphragm strength. EH exposure did not result in any significant change in ventilatory parameters (barometric plethysmography) in awake 6-month old mdx mice. In contrast, 18-month old mdx mice showed considerable ventilatory dysfunction, consistent with reduced ventilatory reserve. Our findings highlight that sleep apnea impacts respiratory and cardiac function in muscular dystrophy, and that EH can have divergent effects on both systems. To our knowledge, this is the first comprehensive study to investigate the impact of EH on cardiac and respiratory function in mdx mice.