Macrophage-specific deletion of Notch-1 induced M2 anti-inflammatory effect in atherosclerosis via activation of the PI3K-oxidative stress axis.

Objective: Notch-1 signaling is significantly associated with the occurrence and development of atherosclerosis (AS). However, the molecular mechanisms underlying the specific deletion of Notch-1 in AS-associated macrophages are not fully understood. This study aimed to investigate the effects of Notch-1 in AS.

Methods And Results: Tissue samples were obtained from atherosclerotic segments of human carotid arteries. Immunofluorescence staining showed that Notch-1 was significantly colocalized with macrophages (CD68+), and Notch-1 staining was increased in human vulnerable plaques. Notch-1/ApoE mice were generated in which Notch-1 was selectively inactivated in macrophages, and WT for littermate control mice (ApoE/Notch-1). A control group was then established. All mice fed with a high-fat and Oil Red O, Movat, a-SMA, CD68, and Sirius red staining were used to evaluate the morphology. Specific deletion of Notch-1 in macrophages repressed the pathophysiology of AS. Immunofluorescent staining and Western blotting revealed that Notch-1 repressed M1 and M2 responses in AS. Here, GSEA revealed that Notch-1 activation and PI3K signaling were statistically significantly correlated with each other, and Notch-1 was involved in the regulation of the PI3K signaling pathway. In the experiments, the secretion of Arg-1 and exosomes was classified by peritoneal macrophages of Notch-1/ApoE and Notch-1/ApoE mice. Immunohistochemistry staining and Western blotting were used to measure the expression levels of Notch1, PI3K, p-PI3K, AKT, p-AKT, Arg-1, IL-6, CD36, SREBP-1, CD206, iNOS, cleaved-caspase-3/-9, Bax, CD9, Alix and TSG101 in the peritoneal macrophages and exosomes, respectively.

Conclusions: The specific deletion of Notch-1 in macrophage represses the formation and development of AS via the PI3K/AKT signaling pathway.