MicroRNA-33–dependent regulation of macrophage metabolism directs immune cell polarization in atherosclerosis
Mireille Ouimet, … , P’ng Loke, Kathryn J. Moore
Mireille Ouimet, … , P’ng Loke, Kathryn J. Moore
Published October 26, 2015
Citation Information: J Clin Invest. 2015;125(12):4334-4348. https://doi.org/10.1172/JCI81676.
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Research Article Vascular biology

MicroRNA-33–dependent regulation of macrophage metabolism directs immune cell polarization in atherosclerosis

Abstract

Cellular metabolism is increasingly recognized as a controller of immune cell fate and function. MicroRNA-33 (miR-33) regulates cellular lipid metabolism and represses genes involved in cholesterol efflux, HDL biogenesis, and fatty acid oxidation. Here, we determined that miR-33–mediated disruption of the balance of aerobic glycolysis and mitochondrial oxidative phosphorylation instructs macrophage inflammatory polarization and shapes innate and adaptive immune responses. Macrophage-specific Mir33 deletion increased oxidative respiration, enhanced spare respiratory capacity, and induced an M2 macrophage polarization–associated gene profile. Furthermore, miR-33–mediated M2 polarization required miR-33 targeting of the energy sensor AMP-activated protein kinase (AMPK), but not cholesterol efflux. Notably, miR-33 inhibition increased macrophage expression of the retinoic acid–producing enzyme aldehyde dehydrogenase family 1, subfamily A2 (ALDH1A2) and retinal dehydrogenase activity both in vitro and in a mouse model. Consistent with the ability of retinoic acid to foster inducible Tregs, miR-33–depleted macrophages had an enhanced capacity to induce forkhead box P3 (FOXP3) expression in naive CD4+ T cells. Finally, treatment of hypercholesterolemic mice with miR-33 inhibitors for 8 weeks resulted in accumulation of inflammation-suppressing M2 macrophages and FOXP3+ Tregs in plaques and reduced atherosclerosis progression. Collectively, these results reveal that miR-33 regulates macrophage inflammation and demonstrate that miR-33 antagonism is atheroprotective, in part, by reducing plaque inflammation by promoting M2 macrophage polarization and Treg induction.

Authors

Mireille Ouimet, Hasini N. Ediriweera, U. Mahesh Gundra, Frederick J. Sheedy, Bhama Ramkhelawon, Susan B. Hutchison, Kaitlyn Rinehold, Coen van Solingen, Morgan D. Fullerton, Katharine Cecchini, Katey J. Rayner, Gregory R. Steinberg, Phillip D. Zamore, Edward A. Fisher, P’ng Loke, Kathryn J. Moore

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Figure 4

miR-33 inhibitors target plaque macrophages to alter macrophage polarization and reduce systemic inflammation.

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miR-33 inhibitors target plaque macrophages to alter macrophage polariza...
(A) Gene expression profile of macrophages isolated from aortic root plaques of control anti-miR or anti–miR-33–treated Ldlr–/– mice using LCM. Data represent the mean of n = 4 mice/group. (B and C) Immunofluorescent staining of aortic root plaques for the 2′F/MOE moiety of the control anti-miR or anti–miR-33 oligonucleotides (green) and (B) arginase 1 (red) or (C) the macrophage marker CD68. Colocalization of staining is seen as yellow in the merged image, with DAPI-stained nuclei in blue. Quantification of arginase 1 staining is shown at right. Data represent the mean ± SEM of n = 4 mice/group. Scale bars: 100 μM. (D) Real-time PCR analysis of peritoneal macrophages isolated from control anti-miR and anti–miR-33–treated Ldlr–/– mice. Data represent the mean ± SEM of n = 4–5 mice per group. (E) Plasma chemokine levels in control anti-miR– or anti–miR-33–treated Ldlr–/– mice. Data represent the mean ± SEM of 5 mice per group. Statistical comparisons were made using 2-tailed Student’s t test (B, D, and E). *P ≤ 0.05; **P ≤ 0.005, compared with control.