miR-99a-5p: A Potential New Therapy for Atherosclerosis by Targeting mTOR and Then Inhibiting NLRP3 Inflammasome Activation and Promoting Macrophage Autophagy

Abstract

Objective. MicroRNAs have been revealed to be involved in the development of atherosclerosis. The present study is aimed at exploring the potential of miR-99a-5p as a therapy for atherosclerosis. We suspected that miR-99a-5p might inhibit NLRP3 inflammasome activation and promote macrophage autophagy via constraining mTOR, therefore, alleviating atherosclerosis. Methods. The cell viability in ox-LDL-induced THP-1 macrophages was assessed by CCK-8 assay. Bioinformatic analysis was used to predict the target genes of miR-99a-5p. The binding between miR-99a-5p and mTOR was confirmed by luciferase reporter assay. In vivo, a high-fat-diet-induced atherosclerosis model was established in apolipoprotein E knockout mice. Hematoxylin-eosin, oil red O, and Sirius red staining were performed for the determination of atherosclerotic lesions. MTOR and associated protein levels were detected by Western blot analysis. Results. miR-99a-5p inhibited NLRP3 inflammasome activation and promoted macrophage autophagy by targeting mTOR. Enforced miR-99a-5p significantly reduced the levels of inflammasome complex and inflammatory cytokines. Furthermore, miR-99a-5p overexpression inhibited the expression of mTOR, whereas mTOR overexpression reversed the trend of the above behaviors. In vivo, the specific overexpression of miR-99a-5p significantly reduced atherosclerotic lesions, accompanied by a significant downregulation of autophagy marker CD68 protein expression. Conclusion. We demonstrated for the first time that miR-99a-5p may be considered a therapy for atherosclerosis. The present study has revealed that miR-99a-5p might inhibit NLRP3 inflammasome activation and promote macrophage autophagy by targeting mTOR, therefore, alleviating atherosclerosis.

Modification of Mesenchymal Stem/Stromal Cell-Derived Small Extracellular Vesicles by Calcitonin Gene Related Peptide (CGRP) Antagonist: Potential Implications for Inflammation and Pain Reversal

“…Deficiency in hsa-miR-21-5p leads to increased recruitment of CD11b+ monocytes/macrophages and an increased inflammatory response [ 50 , 51 ]. Both hsa-miR-99a-5p and miR-574-5p inhibit NLRP3 inflammasome by promoting macrophage autophagy through downregulation of mTOR signaling and by suppressing leukocytes infiltration and downregulating NF-κB [ 52 , 53 ]. Also, miR-107 protects against inflammation and apoptosis of endothelial cells via KRT1-dependent Notch signaling pathway [ 54 ] whereas hsa-let-7b-5p regulates neutrophil function and reduces neutrophilic inflammation by suppressing the canonical TLR4/NF-κB pathway [ 55 ].…”

Evaluation of left ventricular dysfunction by three-dimensional speckle-tracking echocardiography and bioinformatics analysis of circulating exosomal miRNA in obese patients

“…By targeting the homeobox A1 gene, miR-99a-5p acted as an atherosclerosis inhibitor, reducing lesion formation. Recent research showed selective miR-99a-5p overexpression significantly decreased atherosclerotic lesions and lowered NLRP3 inflammatory protein expression [ 26 ], leading to reduced inflammasome complex and inflammatory cytokine levels. Overall, these significant miRNAs, including miR-101-3p, miR-140-3p, and miR-99a-5p, hold clinical utility for the early prediction of obesity-related myocardial injury.…”

The Role of Macrophages in Atherosclerosis: Pathophysiologic Mechanisms and Treatment Considerations

“…Finally, the modulation of microRNAs could be crucial in the regulation of macrophage autophagy. Wang et al, in a study on ox-LDL-induced THP-1 macrophages, found that miR-99a-5p overexpression inhibited NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome activation and stimulated macrophage autophagy through mTOR, producing a lower atherosclerotic lesion burden [49]. Shao et al treated apoE −/− mice and RAW264.7 cells with miR-29a mimic, and found polarization of macrophages toward an M2 phenotype, along with overexpression of autophagy-related proteins [50].…”