Suppressive effect of chrysin on macrophage LC3B autophagy through miR-204-5p in diabetic atherosclerosis

Flavonoid chrysin possesses many biological properties. Autophagy and inflammation interact to cause diabetic cardiovascular diseases. However, whether chrysin affects macrophage autophagy and microRNA 204-5p regulation under hyperglycemic conditions remain unclear. In this study, we examined that the effects of chrysin on the molecular regulatory mechanisms of miR-204-5p in LC3B macrophage autophagy under hyperglycemic stimulation. Macrophages were cultured with 25 mM glucose for hyperglycemia stimulation. A diabetic rat model of carotid artery balloon injury was established. Reverse transcription and real-time quantitative polymerase chain reaction, Western blotting, immunohistochemical staining, and luciferase activity assay were performed. The results indicated that chrysin augmented the macrophage autophagy marker LC3B presentation under high-glucose (HG)-stimulation significantly, however, chrysin attenuated the miR-204-5p level in macrophage cultures. Treatment with chrysin, rapamycin or mutant miR-204-5p increased LC3B presentation through the suppression of miR-204-5p level in macrophage cultures under HG-stimulated condition. By luciferase activity assay, the combination of chrysin with mutant miR-204-5p reduced LC3B binding activity under hyperglycemic stress. Treatment with chrysin (100 mg/kg/day) and wild-type miR-204-5p considerably reduced the neointimal sizes by 46.3% and 36.3%, respectively, at 14 days after carotid artery balloon injury in STZ-induced diabetic rats; ameliorated M1 polarization simultaneously. However, by treating with chrysin suppressed LC3B presentation in diabetic rats. Our findings indicate, under hyperglycemic stress, chrysin regulates the presentation of LC3B autophagy in hyperglycemia-stimulated macrophage cultures and neointimal hyperplasia by mediating the miR-204-5p expression. The results imply that chrysin is potentially effective for preventing hyperglycemia related cardiovascular diseases.