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Macrophage deficiency of miR-21 promotes apoptosis, plaque necrosis, and vascular inflammation during atherogenesis.

ABSTRACT: Atherosclerosis, the major cause of cardiovascular disease, is a chronic inflammatory disease characterized by the accumulation of lipids and inflammatory cells in the artery wall. Aberrant expression of microRNAs has been implicated in the pathophysiological processes underlying the progression of atherosclerosis. Here, we define the contribution of miR-21 in hematopoietic cells during atherogenesis. Interestingly, we found that miR-21 is the most abundant miRNA in macrophages and its absence results in accelerated atherosclerosis, plaque necrosis, and vascular inflammation. miR-21 expression influences foam cell formation, sensitivity to ER-stress-induced apoptosis, and phagocytic clearance capacity. Mechanistically, we discovered that the absence of miR-21 in macrophages increases the expression of the miR-21 target gene, MKK3, promoting the induction of p38-CHOP and JNK signaling. Both pathways enhance macrophage apoptosis and promote the post-translational degradation of ABCG1, a transporter that regulates cholesterol efflux in macrophages. Altogether, these findings reveal a major role for hematopoietic miR-21 in atherogenesis.

SUBMITTER: Canfran-Duque A

PROVIDER: S-EPMC5582411 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Macrophage deficiency of miR-21 promotes apoptosis, plaque necrosis, and vascular inflammation during atherogenesis.

Canfrán-Duque Alberto A Rotllan Noemi N Zhang Xinbo X Fernández-Fuertes Marta M Ramírez-Hidalgo Cristina C Araldi Elisa E Daimiel Lidia L Busto Rebeca R Fernández-Hernando Carlos C Suárez Yajaira Y

EMBO molecular medicine 20170901 9

Atherosclerosis, the major cause of cardiovascular disease, is a chronic inflammatory disease characterized by the accumulation of lipids and inflammatory cells in the artery wall. Aberrant expression of microRNAs has been implicated in the pathophysiological processes underlying the progression of atherosclerosis. Here, we define the contribution of miR-21 in hematopoietic cells during atherogenesis. Interestingly, we found that miR-21 is the most abundant miRNA in macrophages and its absence r ...[more]

PMID: 28674080

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Project description:BackgroundCross-talk between sterol metabolism and inflammatory pathways has been demonstrated to significantly affect the development of atherosclerosis. Cholesterol biosynthetic intermediates and derivatives are increasingly recognized as key immune regulators of macrophages in response to innate immune activation and lipid overloading. 25-Hydroxycholesterol (25-HC) is produced as an oxidation product of cholesterol by the enzyme cholesterol 25-hydroxylase (CH25H) and belongs to a family of bioactive cholesterol derivatives produced by cells in response to fluctuating cholesterol levels and immune activation. Despite the major role of 25-HC as a mediator of innate and adaptive immune responses, its contribution during the progression of atherosclerosis remains unclear.MethodsThe levels of 25-HC were analyzed by liquid chromatography-mass spectrometry, and the expression of CH25H in different macrophage populations of human or mouse atherosclerotic plaques, respectively. The effect of CH25H on atherosclerosis progression was analyzed by bone marrow adoptive transfer of cells from wild-type or Ch25h-/- mice to lethally irradiated Ldlr-/- mice, followed by a Western diet feeding for 12 weeks. Lipidomic, transcriptomic analysis and effects on macrophage function and signaling were analyzed in vitro from lipid-loaded macrophage isolated from Ldlr-/- or Ch25h-/-;Ldlr-/- mice. The contribution of secreted 25-HC to fibrous cap formation was analyzed using a smooth muscle cell lineage-tracing mouse model, Myh11ERT2CREmT/mG;Ldlr-/-, adoptively transferred with wild-type or Ch25h-/- mice bone marrow followed by 12 weeks of Western diet feeding.ResultsWe found that 25-HC accumulated in human coronary atherosclerotic lesions and that macrophage-derived 25-HC accelerated atherosclerosis progression, promoting plaque instability through autocrine and paracrine actions. 25-HC amplified the inflammatory response of lipid-loaded macrophages and inhibited the migration of smooth muscle cells within the plaque. 25-HC intensified inflammatory responses of lipid-laden macrophages by modifying the pool of accessible cholesterol in the plasma membrane, which altered Toll-like receptor 4 signaling, promoted nuclear factor-κB-mediated proinflammatory gene expression, and increased apoptosis susceptibility. These effects were independent of 25-HC-mediated modulation of liver X receptor or SREBP (sterol regulatory element-binding protein) transcriptional activity.ConclusionsProduction of 25-HC by activated macrophages amplifies their inflammatory phenotype, thus promoting atherogenesis.

Project description:AimsAtherosclerotic plaque hypoxia is detrimental for macrophage function. Prolyl hydroxylases (PHDs) initiate cellular hypoxic responses, possibly influencing macrophage function in plaque hypoxia. Thus, we aimed to elucidate the role of myeloid PHDs in atherosclerosis.Methods and resultsMyeloid-specific PHD knockout (PHDko) mice were obtained via bone marrow transplantation (PHD1ko, PHD3ko) or conditional knockdown through lysozyme M-driven Cre recombinase (PHD2cko). Mice were fed high cholesterol diet for 6-12 weeks to induce atherosclerosis. Aortic root plaque size was significantly augmented 2.6-fold in PHD2cko, and 1.4-fold in PHD3ko compared to controls but was unchanged in PHD1ko mice. Macrophage apoptosis was promoted in PHD2cko and PHD3ko mice in vitro and in vivo, via the hypoxia-inducible factor (HIF) 1α/BNIP3 axis. Bulk and single-cell RNA data of PHD2cko bone marrow-derived macrophages (BMDMs) and plaque macrophages, respectively, showed enhanced HIF1α/BNIP3 signalling, which was validated in vitro by siRNA silencing. Human plaque BNIP3 mRNA was positively associated with plaque necrotic core size, suggesting similar pro-apoptotic effects in human. Furthermore, PHD2cko plaques displayed enhanced fibrosis, while macrophage collagen breakdown by matrix metalloproteinases, collagen production, and proliferation were unaltered. Instead, PHD2cko BMDMs enhanced fibroblast collagen secretion in a paracrine manner. In silico analysis of macrophage-fibroblast communication predicted SPP1 (osteopontin) signalling as regulator, which was corroborated by enhanced plaque SPP1 protein in vivo. Increased SPP1 mRNA expression upon PHD2cko was preferentially observed in foamy plaque macrophages expressing 'triggering receptor expressed on myeloid cells-2' (TREM2hi) evidenced by single-cell RNA, but not in neutrophils. This confirmed enhanced fibrotic signalling by PHD2cko macrophages to fibroblasts, in vitro as well as in vivo.ConclusionMyeloid PHD2cko and PHD3ko enhanced atherosclerotic plaque growth and macrophage apoptosis, while PHD2cko macrophages further activated collagen secretion by fibroblasts in vitro, likely via paracrine SPP1 signalling through TREM2hi macrophages.

Project description:microRNA-155 (miR155) plays a critical role in immunity and macrophage inflammation. We aim to investigate the role of miR155 in atherogenesis.Quantitative real-time polymerase chain reaction showed that miR155 was expressed in mouse and human atherosclerotic lesions. miR155 expression in macrophages was correlated positively with proinflammatory cytokine expression. Lentivirus-mediated overexpression of miR155 in macrophages enhanced their inflammatory response to lipopolysaccharide through targeting suppressor of cytokine signaling-1 and impaired cholesterol efflux from acetylated low-density lipoprotein-loaded macrophages, whereas deficiency of miR155 blunted macrophage inflammatory responses and enhanced cholesterol efflux possibly via enhancing lipid loading-induced macrophage autophagy. We next examined the atherogenesis in apolipoprotein E-deficient (apoE(-/-)) and miR155(-/-)/apoE(-/-) (double knockout) mice fed a Western diet. Compared with apoE(-/-) mice, the double knockout mice developed less atherosclerosis lesion in aortic root, with reduced neutral lipid content and macrophages. Flow cytometric analysis showed that there were increased number of regulatory T cells and reduced numbers of Th17 cells and CD11b+/Ly6C(high) cells in the spleen of double knockout mice. Peritoneal macrophages from the double knockout mice had significantly reduced proinflammatory cytokine expression and secretion both in the absence and presence of lipopolysaccharide stimulation. To determine whether miR155 in leukocytes contributes to atherosclerosis, we performed a bone marrow transplantation study. Deficiency of miR155 in bone marrow-derived cells suppressed atherogenesis in apoE(-/-) mice, demonstrating that hematopoietic cell-derived miR155 plays a critical role.miR155 deficiency attenuates atherogenesis in apoE(-/-) mice by reducing inflammatory responses of macrophages, enhancing macrophage cholesterol efflux and resulting in an antiatherogenic leukocyte profile. Targeting miR155 may be a promising strategy to halt atherogenesis.

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Macrophage deficiency of miR-21 promotes apoptosis, plaque necrosis, and vascular inflammation during atherogenesis.

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Macrophage deficiency of miR-21 promotes apoptosis, plaque necrosis, and vascular inflammation during atherogenesis.

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