Forced expression of microRNA-146b reduces TRAF6-dependent inflammation and improves ischemia-induced neovascularization in hypercholesterolemic conditions


      • Neovascularization is impaired in animal models and patients presenting hypercholesterolemia.
      • MicroRNA-146b is reduced by hypercholesterolemia, which leads to TRAF6-dependent inflammation and impaired angiogenesis.
      • Forced expression of miR-146b could reduce inflammation and improve neovascularization in atherosclerotic conditions.


      Background and aims

      MicroRNA (miR)-146 is a key regulator of inflammation, endothelial activation and atherosclerosis. This study sought to define its potential role for the modulation of ischemia-induced neovascularization in atherosclerotic conditions.


      Next generation sequencing and qRT-PCR analyses were used to compare microRNA expression in the ischemic muscles of hypercholesterolemic ApoE-deficient (ApoE−/−) mice vs. wild type mice, and in HUVECs exposed or not to oxLDL. Neovascularization was investigated in a mouse model of hindlimb ischemia and the functional activities of HUVECs and pro-angiogenic cells (PACs) were assessed in vitro.


      We found that miR-146b (but not miR-146a) is significantly reduced in the ischemic muscles of ApoE−/− mice, and in HUVECs exposed to oxLDL. Inhibition of miR-146b reduces angiogenesis in vitro, whereas forced expression of miR-146b rescues oxLDL-mediated impairment of endothelial cell proliferation and tube formation. Mechanistically, miR146b directly targets tumor necrosis factor-alpha (TNFa) Receptor Associated Factor 6 (TRAF6) to inhibit inflammation. We found that hypercholesterolemia and oxLDL exposure are associated with higher levels of TRAF6, and increased expression of TNFa. However, forced expression of miR-146b in high cholesterol conditions reduces the expression of these inflammatory factors. In vivo, intramuscular injection of miR-146b mimic reduces ischemic damages and restores blood flow recuperation and capillary density in the ischemic muscles of ApoE−/− mice. Treatment with miR-146b also increases the number and functional activities of pro-angiogenic cells (PACs).


      Hypercholesterolemia is associated with reduced expression of miR-146b, which increases TRAF6-dependent inflammation and is associated with poor neovascularization in response to ischemia. Forced expression of miR-146b using a miR mimic could constitute a novel therapeutic strategy to improve ischemia-induced neovascularization in atherosclerotic conditions.

      Graphical abstract


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