MicroRNA-216a promotes M1 macrophages polarization and atherosclerosis progression by activating telomerase via the Smad3/NF-κB pathway.

Macrophages exhibit heterogeneity and plasticity and imbalance between pro-inflammatory and anti-inflammatory macrophages plays a critical role in atherosclerosis progression. Telomerase reverse transcriptase (TERT) in macrophages can be activated by nuclear factor-kappa B (NF-κB), but the regulation of telomerase activation on macrophages polarization remains unknown. We previously identified microRNA-216a (miR-216a) to promote inflammation through directly targeting the Smad3/NF-κB pathway. The present study aimed to assess whether miR-216a can regulate telomerase activity and promote macrophages polarization during atherosclerosis progression. The results verified that TERT was highly expressed in macrophages of human carotid atherosclerotic plaques. miR-216a was found to promote telomerase activation in macrophages by 4.5-fold (P = 0.002) through the Smad3/NF-κB pathway. miR-216a also induced macrophages senescence characterized by senescence-associated-β-galactosidase activity and p53 and p16 expression. TERT overexpression promoted the transformation of M2 to M1 while this conversion was suppressed once TERT was inhibited, and the related inflammatory factors and lipid uptake ability of M1 cells were also increased by TERT. In the carotid atherosclerotic plaques from miR-216a-treated apolipoprotein E^-/- mice, the numbers of M1 macrophages were increased whereas M2 cells reduced, accompanying with inhibited Smad3 expression and upregulated inflammatory markers and TERT activity. Furthermore, plasma miR-216a level was specifically higher in patients with vulnerable mixed plaques (n = 181) than those with calcified plaques (n = 73) and controls (n = 264). In summary, our findings first revealed a new molecular mechanism of macrophage polarization involving telomerase activation induced by miR-216a through the Smad3/NF-κB signaling, which might serve as a potential therapeutic target for atherosclerosis progression.

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