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

Abstract

Background: 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.

Methods: 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 CD68⁺ magnetic beads. 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.

Results: 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 and the CCR5 antagonist maraviroc were identified as potential clinical interventions for inhibiting senescent foamy macrophage formation and atherosclerosis progression.

Conclusions: 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.