Background In recent years, several studies have shown that sodium-glucose cotransporter 2 (SGLT2) inhibitors may reduce the incidence of cardiovascular events in patients with type 2 diabetes, while the related mechanisms remain to be further studied.
Objective To investigate the effect and mechanism of dapagliflozin, one of SGLT2 inhibitors, on diabetic atherosclerotic (AS) plaque.
Methods ApoE-/- mice were used to construct the models of AS. Then the mice were divided into AS control group (Con), diabetic AS insulin intervention group (Insulin) and diabetic AS dapagliflozin intervention group (Dapa) with 10 mice in each group, and the levels of blood glucose, body weight and blood lipid were monitored regularly. At 8 weeks after intra-abdominal injection of insulin and dapagliflozin, the mice were sacrificed. Aortae were taken for gross oil red O staining, and aortic root sections were taken for oil red O staining, HE staining and immunohistochemical staining, to evaluate atherosclerotic lesion and infiltration of macrophages in plaque. Mouse macrophages line RAW264.7 were cultured, and appropriate intervention concentration of dapagliflozin was determined by CCK-8 toxicity test. After cultured for 72 hours, the effect of dapagliflozin on macrophage proliferation was detected by CCK-8 proliferation assay, and apoptosis-related protein Cleaved Caspase 3 (CL Caspase 3) was detected by western blot. RAW264.7 was induced by lipopolysaccharide (LPS) to construct an inflammatory model, and blank control group, inflammation control group and dapagliflozin intervention group were set up, respectively. The secretion levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1) and granulocyte macrophage colony-stimulating factor (GM-CSF) in macrophages supernatant were determined by enzyme-linked immunosorbent assay (ELISA).
Results There was no significant difference between Insulin group and Dapa group in blood glucose, body weight or blood lipid. Gross oil red O staining showed that the AS area in Dapa group was 38% lower than that in Insulin group (P ＜ 0.05). HE staining showed that the plaque load in Dapa group was 25% less than that in Insulin group (P ＜0.05). Immunohistochemical staining showed that the number of F4/80 positive macrophages in Dapa group was significantly lower than that in Insulin group (P ＜ 0.01). CCK-8 toxicity test indicated that the appropriate concentration of dapagliflozin on macrophage in vitro was 50 μmol/L. CCK-8 proliferation assay showed that dapagliflozin significantly inhibited the proliferation of macrophages (P ＜ 0.05), and Western blot showed that there was no significant change in CL Caspase 3 expression after dapagliflozin intervention. ELISA showed that dapagliflozin could significantly reduce macrophages secretion of IL-6 (P ＜ 0.05), MCP-1 (P ＜ 0.05) and GM-CSF (P ＜ 0.01).
Conclusion Dapagliflozin can reduce the infiltration of macrophages in plaque and alleviate atherosclerosis in diabetes mellitus, which may be related to the inhibition of macrophages proliferation and the secretion of GM-CSF.
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