Distinct immunometabolic signatures of type 1 versus type 2 diabetes in a murine model of myocardial infarction

Background: Diabetes mellitus (DM), which consists of type I and type 2 diabetes (T1D and T2D), is a known risk factor for myocardial infarction (MI) and negatively impacts post-MI outcomes. However, the mechanisms by which DM exacerbates cardiac remodeling in T1D versus T2D have not been well defined. Here, we assessed acute and chronic post-MI outcomes in T1D and T2D mice, focusing on immune and metabolic pathways. Methods: T1D was induced in adult male mice by a single high dose of streptozotocin (STZ), and T2D induced by high fat/fructose feeding and multiple low STZ doses. Two weeks following STZ administration, MI was induced by permanent coronary artery ligation, and mice were studied at days (D) 3, 7, and 28 post-MI. Cardiac function was assessed by echocardiography. Results: Compared to non-diabetic mice, T1D and T2D mice had worse cardiac dysfunction after MI, including increased wall thinning and decreased ejection fraction, despite similar infarct sizes. T1D mice also displayed acute pulmonary congestion. By RNA-sequencing analysis, T1D and T2D mice displayed upregulation of genes associated with canonical chemokine/monocyte-mediated inflammatory pathways, and downregulation of genes associated with extracellular matrix remodeling. T1D and T2D delayed activation of M2-like (CD206+) macrophages in the heart, and impaired normal collagen and elastin deposition after MI. T2D also increased expression of genes associated with T cell activation, and increased CD8+ T cells in the infarct. T1D and T2D hearts showed signs of impaired glucose and ketone oxidation, and T1D hearts had increased markers of fatty acid oxidation. Extracted D3 cardiac macrophages from T1D and T2D mice exhibited higher basal oxygen consumption, and increased M1 markers and chemokine expression. Plasma from T1D and T2D mice increased chemokine expression (Ccl2, Ccl7, Cxcl1) in cultured bone marrow macrophages, and T2D plasma impaired mitochondrial function. Conclusions: DM promotes adverse cardiac remodeling, which is associated with activation of overlapping and unique inflammatory pathways, impaired ECM remodeling, remote metabolic remodeling, and alterations in macrophage metabolism. Our results provide novel insights into potential therapeutic pathways for DM patients suffering from MI.