Background - Atherosclerosis (ATH) is a chronic systemic inflammatory disease affecting the vessel wall, wherein regulating non-coding RNAs play a crucial role. We previously demonstrated that miR-125b is upregulated in ATH and is a main regulator of cholesterol metabolism in macrophages. Herein we hypothesized that inhibiting miR-125b may attenuate ATH. Methods and results - In the ApoE-/- mice model fed with a high fat diet for 14 weeks, we inhibited miR-125b using an antagomiR over a 4-week period. We observed a significant reduction in plaque size, accompanied by diminished infiltration of F4/80 macrophages and attenuation of NF-κB+ activation within plaques. We explored the mechanism using a Vas-on-Chip adhesion assay using Human Aortic Endothelial Cells (HAoEC) stimulated with TNFα. We observed an impairment in the trafficking of miR-125b transfected THP-1 monocytes, accompanied by the downregulation of the CD11b/CD18 integrin and the CCR7 receptor. Furthermore, we demonstrated a direct regulation of the CCR7 receptor by miR-125b using a reporter plasmid construct (p_CCR7.WT) containing the 3-UTR region of CCR7 gene fused with a luciferase coding sequence. In addition, miR-125b transfected monocytes inhibited CCR7 cell migration induced by the CCL21 ligand but did not affect migration induced by others ligands such as MCP1. Finally, we confirmed the downregulation of CCR7 in coronary plaques in both ApoE-/- mice and patients with coronary artery disease. Conclusions - Inhibiting miR-125b offers a novel therapeutic approach for ameliorating ATH that results in a reduction of macrophage content and plaque lesion size. This improvement occurs through the enhancement of monocyte trafficking via CCR7 that facilitates the exit of foam cells from the plaque.

The authors have declared no competing interest.

This study has been funded by the Instituto de Salud Carlos III (Co-funded by the European Regional Development Fund (ERDF), a way to build Europe) through the project PI 18/01108 and PI23/00927 (to M.H) and by Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS) (RD21/0005/0001). This work was also funded by Ministerio de Ciencia, Innovación y Universidades (PID2019-104367RB-100), as well as from the Agencia Estatal de Investigación (AEI/10.13039/501100011033) within the Subprograma Ramón y Cajal (RYC-201722879) to NR.

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All the experimental procedures in animals were approved by the Ethics Committee for Animal Research of UB-Bellvitge (85/20, approved on February 24th, 2021), and performed in accordance with the European legislation on Laboratory Animal Experiments. Samples and data from patients included in this study were provided by the Biobank HUB-ICO-IDIBELL (PT17/0015/0024), which is integrated in the Spanish National Biobanks Network. The study was approved by the ethics committee of Bellvitge University Hospital (PR149/14, approved on May 19th, 2016) and all participants provided their written informed consent.

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All experimental data referenced in this manuscript are available upon request. Researchers interested in accessing the data should contact to the corresponding author (MH).