N⁶-Methyladenosine Demethylase FTO Controls Macrophage Homeostasis in Diabetic Vasculopathy

Diabetic vasculopathy, encompassing complications such as diabetic retinopathy, represents a significant source of morbidity, with inflammation playing a pivotal role in the progression of these complications. This study investigates the influence of N⁶-methyladenosine demethylase (m⁶A) modification and the m⁶A demethylase fat mass and obesity-associated (FTO) protein on macrophage polarization and its subsequent effects on diabetic microvasculopathy. We found that diabetes induces a shift in macrophage polarization toward a proinflammatory M1 phenotype, which is associated with a reduction in m⁶A modification levels. Notably, FTO emerges as a critical regulator of m⁶A under diabetic conditions. In vitro experiments reveal that FTO not only modulates macrophage polarization but also mediates their interactions with vascular endothelial cells. In vivo experiments demonstrate that FTO deficiency exacerbates retinal inflammation and microvascular dysfunction in diabetic retinas. Mechanistically, FTO stabilizes mRNA through an m⁶A-YTHDF2–dependent pathway, thereby activating the PI3K/AKT signaling cascade. Collectively, these findings position FTO as a promising therapeutic target for the management of diabetic vascular complications.

• The fat mass and obesity-associated (FTO) protein is a key regulator for decreased N⁶-methyladenosine modification in diabetes-induced macrophage polarization.

• FTO not only modulates macrophage polarization but also mediates their interactions with vascular endothelial cells.

• FTO deficiency exacerbates retinal inflammation and microvascular dysfunction in diabetic retinas.

• FTO stabilizes mRNA through an N⁶-methyladenosine-YTHDF2–dependent pathway, thereby activating the PI3K/AKT signaling cascade.