ALKBH5 Regulates Macrophage Senescence and Accelerates Atherosclerosis by Promoting CCL5 m⁶A Modification

Senescent foamy macrophages are key drivers of atherosclerosis and plaque instability. N⁶-methyladenosine (m⁶A) modification of RNA plays an important role in the development of various diseases including aging. Here, we aim to investigate the role of m⁶A modification of RNA in the formation of senescent foamy macrophages in atherosclerosis.

To assess m⁶A methylation, macrophages were isolated from the atherosclerotic plaques of patients with atherosclerosis, and Apoe^-/- mice were fed a high-fat diet using flow cytometry. An ALKBH5 (alkB homolog 5)^f/f, Lyz2 (lysozyme 2)^Cre, Apoe^-/- mouse model was generated to determine the infiltration of senescent foamy macrophages into plaques and atherosclerosis progression. Methylated RNA immunoprecipitation, RNA immunoprecipitation sequencing, and dual-luciferase assays were performed to explore the mechanisms underlying the ALKBH5-mediated formation of senescent foamy macrophages.

Decreased m⁶A methylation and increased ALKBH5 expression were observed in arterial plaques and infiltrating macrophages from patients and mice with atherosclerosis. Compared with control mice, ALKBH5^f/f, Lyz2^Cre, Apoe^-/- mice exhibited fewer atherosclerosis plaques with greater stability, which was attributed to the suppression of senescent foamy macrophage formation and senescence-associated secretory phenotype. In addition, ALKBH5 deletion reduced the mRNA expression level of CCL5 (CC chemokine ligand 5) by increasing m⁶A methylation in macrophages, which disrupts the stability of CCL5 mRNA. Mechanistically, ALKBH5 promoted senescent foamy macrophage formation through the CCL5/CCR5 (CC chemokine receptor 5)/autophagy signaling pathway. CCL5 also recruited CD8⁺ IFN (interferon)γ⁺ T cells via the CCL5-CCR5 axis. The ALKBH5 inhibitor IOX1 (inhibitor of 2OG oxygenases) and the CCR5 antagonist maraviroc were identified as potential clinical interventions for inhibiting senescent foamy macrophage formation and atherosclerosis progression.

Myeloid ALKBH5 deletion attenuates atherosclerosis progression by suppressing the formation of senescent foamy macrophages and the recruitment of CD8⁺IFNγ⁺ T cells. These findings identify ALKBH5, CCL5, and CCR5 as novel therapeutic targets for atherosclerosis.