Xiao Qun Wang

MiR-146a inhibits oxidized low-density lipoprotein-induced lipid accumulation and inflammatory response via targeting toll-like receptor 4.

Atherosclerosis is an inflammatory process due to oxidized low‐density lipoprotein (oxLDL) accumulation in macrophages. We investigated the involvement of microRNAs in oxLDL accumulation and inflammatory response in macrophages. The expression of miR‐146a decreases under oxLDL stimulation. MiR‐146a significantly reduces intracellular LDL cholesterol content and secretion of interleukin 6, interleukin 8, chemokine (C–C motif) ligand 2 and matrix metallopeptidase 9. Toll‐like receptor 4 (TLR4) is a relevant target of miR‐146a, and miR‐146a inhibits the activation of TLR4‐dependent intracellular signaling pathways involved in cytoskeleton rearrangement, lipid uptake, and inflammatory cytokine secretion. These results indicate that miR‐146a contributes to the regulation of both oxLDL accumulation and inflammatory response by negatively regulating TLR4 and thereby inhibiting the activation of TLR4‐dependent signaling pathways. Over‐expression of miR‐146a may be useful in the prevention and treatment of atherosclerosis.

Advanced glycation end products induce chemokine/cytokine production via activation of p38 pathway and inhibit proliferation and migration of bone marrow mesenchymal stem cells.

BackgroundAdvanced glycation products (AGEs), as endogenous inflammatory mediator, compromise the physiological function of mesenchymal stem cells (MSCs). MSCs have a potential role in cell replacement therapy in acute myocardial infarction and ischemic cardiomyopathy. However, mechanisms of AGEs on MSCs are still not unveiled.MethodsReactive oxygen species (ROS), genes regulation, cell proliferation and migration have been detected by AGE-BSA stimulated MSCs.ResultsWe found that in vitro stimulation with AGE-BSA induced generation of reactive oxygen species (ROS), and inhibited dose-dependently proliferation and migration of MSCs. Microarray and molecular biological assessment displayed an increased expression and secretion of Ccl2, Ccl3, Ccl4 and Il1b in a dose- and time-dependent manner. These chemokines/cytokines of equivalent concentration to those in conditioned medium exerted an inhibitory effect on MSC proliferation and migration after stimulation for 24 h. Transient elevation of phospho-p38 in MSCs upon AGE-BSA stimulation was blocked with p38 inhibitor.ConclusionsThe study indicates that AGE-BSA induces production of chemokines/cytokines in a dose- and time-dependent manner via activation of ROS-p38 mediated pathway. These chemokines/cytokines exert an inhibitory effect on MSC growth and migration, suggesting an amplified dysfunction of MSCs by AGEs.

C1q/TNF-related protein-1: an adipokine marking and promoting atherosclerosis

AIMS We investigated the association of the adipokine C1q/TNF-related protein (CTRP) 1 with coronary artery disease (CAD), and the biological vascular effects of CTRP1. METHODS AND RESULTS We analysed CTRP1 levels in sera of CAD patients (n = 451) and non-CAD controls (n = 686), and in coronary endarterectomy specimens (n = 32), non-atherosclerotic internal mammary arteries (n = 26), aortic atherosclerotic plaques (n = 15), and non-atherosclerotic aortic samples (n = 10). C1q/TNF-related protein-levels were higher in sera, endarterectomy specimens, aortic atherosclerotic plaques, and peripheral blood mononuclear cells (PBMCs) from CAD patients compared with controls, and were related to CAD severity. The production of CTRP1 was profusely induced by inflammatory cytokines and itself caused a concentration-dependent expression of adhesion molecules and inflammatory markers in human endothelial cells, human peripheral blood monocytes, and THP-1 cells. C1q/TNF-related protein-1 induced p38-dependent monocyte-endothelium adhesion in vitro and the recruitment of leucocytes to mesenteric venules in C57BL/6 mice. Immunohistochemistry of atherosclerotic femoral arteries exhibited CD68 and VE-cadherin loci-associated increased CTRP1 expression in plaques. Compared with saline, intraperitoneal injection of recombinant CTRP1 protein (200 μg/kg) every other day promoted atherogenesis in apoE(-/-) mice at 24 weeks. However, pro-atherogenic effects were significantly attenuated in CTRP1(-/-)/apoE(-/-) double-knockout mice compared with apoE(-/-) mice, with a consistent decrease in vascular adhesion molecule, phospho-p38 and TNF-α expression and macrophage infiltration in plaque in CTRP1(-/-) and double-knockout mice. Tumour necrosis factor-α-induced expression of adhesion molecules and cytokines were lower in primary endothelial cells and macrophages from CTRP(-/-) mice than in those from C57BL/6 mice. CONCLUSION C1q/TNF-related protein-1 is a marker of atherosclerosis in humans and promotes atherogenesis in mice.

Toll-like receptor 4 mediates inflammatory cytokine secretion in smooth muscle cells induced by oxidized low-density lipoprotein.

Oxidized low-density lipoprotein (oxLDL)-regulated secretion of inflammatory cytokines in smooth muscle cells (SMCs) is regarded as an important step in the progression of atherosclerosis; however, its underlying mechanism remains unclear. This study investigated the role of toll-like receptor 4 (TLR4) in oxLDL-induced expression of inflammatory cytokines in SMCs both in vivo and in vitro. We found that the levels of TLR4, interleukin 1-β (IL1-β), tumor necrosis factor-α (TNFα), monocyte chemoattractant protein 1 (MCP-1) and matrix metalloproteinase-2 (MMP-2) expression were increased in the SMCs of atherosclerotic plaques in patients with femoral artery stenosis. In cultured primary arterial SMCs from wild type mice, oxLDL caused dose- and time-dependent increase in the expression levels of TLR4 and cytokines. These effects were significantly weakened in arterial SMCs derived from TLR4 knockout mice (TLR4−/−). Moreover, the secretion of inflammatory cytokines was blocked by TLR4-specific antibodies in primary SMCs. Ox-LDL induced activation of p38 and NFκB was also inhibited in TLR4−/− primary SMCs or when treated with TLR4-specific antibodies. These results demonstrated that TLR4 is a crucial mediator in oxLDL-induced inflammatory cytokine expression and secretion, and p38 and NFκB activation.

Receptor Mediated Elevation in FABP4 Levels by Advanced Glycation End Products Induces Cholesterol and Triacylglycerol Accumulation in THP-1 Macrophages

Excessive formation of advanced glycation end products (AGE) and lipid accumulation in macrophages play a pivotal role in the progression of atherosclerosis in diabetes mellitus. This study aimed to determine the molecular link between AGE-induced fatty acid binding protein 4 (FABP4) expression and macrophage lipid accumulation. AGE–BSA markedly increased macrophage FABP4 expression via engagement of RAGE, a 35-kDa transmembrane receptor that is able to bind extracellular AGE and responsible for the corresponding signal transduction, whereas knockdown of RAGE significantly reversed the FABP4 up-regulation. This effect was further paralleled with elevated intracellular total cholesterol and triacylglycerol levels. Finally, administration of FABP4 inhibitor totally abolished the increased lipid contents in response to AGE–BSA. These results indicate that FABP4 up-regulation is responsible for the enhanced macrophage lipid accumulation by AGE, which may underlie the accelerated formation of foam cells and development of atherosclerotic cardiovascular diseases in diabetic patients.

C1q/TNF-related protein 1 links macrophage lipid metabolism to inflammation and atherosclerosis

BACKGROUND AND AIMS Macrophage is a major contributor to the development of atherosclerosis by taking up deposited lipoprotein and eliciting local inflammation. Previously, we and others have shown C1q/TNF-related proteins (CTRPs) play diverse roles in vascular functions. In this study, we sought to investigate the changes in CTRP expression levels during vital biological processes in macrophages and their relation to inflammatory responses. METHODS Western blot and real-time PCR were performed to analyze CTRPs expression levels in human peripheral blood mononuclear cells, primary macrophages and lipid-laden foam cells. Mechanisms that regulate CTPR1 expression were further investigated by bioinformatic analysis and chromatin immunoprecipitation. Enzyme-linked immunosorbent assay was performed to measure the concentration of inflammatory cytokines. RESULTS We found that almost all CTRPs were significantly increased in primary human macrophages after differentiation from peripheral blood mononuclear cells. In particular, CTRP1 was further up-regulated upon exposure to oxidized low-density lipoprotein (oxLDL) in a peroxisome proliferator-activated receptor (PPAR)-dependent manner. Chromatin immunoprecipitation also confirmed the presence of PPAR-γ in the CTRP1 promoter after oxLDL treatment. Stimulation of CTRP1 led to markedly enhanced secretion of pro-atherogenic factors, including MCP-1, TNF-α, IL-1β, and IL-6, whereas oxLDL-induced inflammatory cytokine production was significantly attenuated after the treatment with CTRP1 neutralizing antibody. CONCLUSIONS These data suggest an essential role of CTRP1 in linking dysregulation of lipid metabolism and inflammatory responses in macrophages.

ASSOCIATION OF SERUM HMGB2 LEVEL WITH MACE AT 1 MONTH OF MYOCARDIAL INFARCTION: AGGRAVATION OF MYOCARDIAL ISCHEMIC INJURY IN RAT BY HMGB2 VIA ROS

High-mobility group box (HMGB) family is related to inflammatory diseases. We investigated whether serum HMGB2 levels are related to myocardial infarction (MI) severity and major adverse cardiac events (MACE) during MI. We included 432 consecutive patients with ST-segment elevation myocardial infarction and 312 controls. Serum HMGB2 levels were significantly higher in MI patients than in controls. Increased HMGB2 levels were associated with MACE and negatively with ejection fraction in MI patients. HMGB2 was an independent determinant of MACE in logistic regression analysis. HMGB2 protein (10 μg) or saline was injected intramyocardially in MI rats, with or without coadministration of the NADPH oxidase inhibitor apocynin. After 72 h, pathological, echocardiographic, and hemodynamic examinations showed that HMGB2 increased infarct size and worsened cardiac function in MI rats. Moreover, HMGB2 administration enhanced reactive oxygen species (ROS) production, cell apoptosis, inflammation, and autophagosome clearance impairment, which were attenuated by coadministration of apocynin or knock down of receptor for advanced glycation end products (RAGE). In conclusion, increased serum HMGB2 levels are associated with MI severity and MACE at 1 mo. HMGB2 promotes myocardial ischemic injury in rats and hypoxic H9C2 cell damage via ROS provoked by RAGE.NEW & NOTEWORTHY We demonstrate that serum high-mobility group box 2 is associated with major adverse cardiac events at 1 mo in myocardial infarction patients. Mechanistically, high-mobility group box 2 promotes reactive oxygen species production via receptor for advanced glycation end products signaling in ischemic myocardium, thereby aggravating cell apoptosis, inflammation, and autophagosome clearance impairment. This study reveals that high-mobility group box 2 is a novel factor enhancing ischemic injury in myocardial infarction.

Increased serum TREM-1 level is associated with in-stent restenosis, and activation of TREM-1 promotes inflammation, proliferation and migration in vascular smooth muscle cells.

BACKGROUND AND AIMS In-stent restenosis (ISR) remains a major limitation of percutaneous coronary intervention despite improvements in stent design and pharmacological agents, whereas the mechanism of ISR has not been fully clarified. In the present study, we sought to investigate the potential association of serum soluble TREM-1 (sTREM-1) levels with the incidence of ISR. The role of TREM-1 was evaluated in cultured vascular smooth muscle cells (VSMCs). METHODS Out of 1683 patients undergoing coronary intervention and follow-up coronary angiography after approximately one year, 130 patients were diagnosed with ISR, and 150 gender- and age-matched patients with no ISR were randomly included as controls. Levels of sTREM-1 were determined by ELISA. The role of TREM-1 signaling in the activation of VSMCs was tested. RESULTS Serum sTREM-1 concentrations were significantly elevated in patients with than without ISR. Multivariable logistic regression analysis showed that sTREM-1, besides conventional factors, was independently associated with the incidence of ISR. Evident expression of TREM-1 in VSMCs was detected in the neointimal and medial layers of stenotic lesions of mouse carotid ligation models. In cultured VSMCs, expression of TREM-1 was significantly induced upon exposure to lipopolysaccharide. Blocking of TREM-1 with a synthetic inhibitory peptide LP17 dramatically inhibited, whereas TREM-1-activating antibody promoted cellular inflammation, proliferation and migration in VSMCs. CONCLUSIONS These data suggest that TREM-1 is a predictive biomarker of ISR and an important mediator of cellular inflammation, migration, and proliferation in VSMCs. Pharmacological inhibition of TREM-1 may serve as a promising approach to attenuate the progression of ISR.

C1q/TNF-related protein 1 promotes endothelial barrier dysfunction under disturbed flow

Endothelial hyper-permeability is a major determinant factor that contributes to the accelerated development of atherosclerotic lesions at hemodynamically disturbed sites. Previously, we showed that C1q/TNF related protein (CTRP) 1 promotes endothelium-leukocyte interactions and inflammatory responses in vascular cells. Here, we sought to investigate the role of CTRP1 in modulation of endothelial permeability under disturbed flow condition. By using en face staining of mouse aorta, we found CTRP1 expression was significantly increased in vascular endothelial cells under disturbed flow as compared to steady laminar flow. Vascular permeability to Evans blue dye was notably enhanced in CTRP1 knockin mice as compared to wild type animals, whereas aortic hyper-permeability at disturbed sites was remarkably restored after deletion of CTRP1. In cultured endothelial cells, treatment of CTRP1 led to increased permeability to fluorescent-labelled dextran and apparent formation of paracellular holes as observed after disturbed flow exposure, which was evidently reduced in the presence of a CTRP1-specific neutralizing antibody. Mechanistically, we found activation of VEGFR2 by CTRP1 might be involved in vascular hyper-permeability under disturbed flow condition. Taken together, this study suggests that CTRP1 is a mechano-sensitive proinflammatory factor that mediates disturbed flow-induced vascular barrier dysfunction. Inhibition of CTRP1 may inhibit the pathogenesis of atherosclerosis at early stage.

Association of Serum HMGB2 Levels With In-Stent Restenosis: HMGB2 Promotes Neointimal Hyperplasia in Mice With Femoral Artery Injury and Proliferation and Migration of VSMCs

Objective— In a previous study, we established diabetic and nondiabetic minipig models with coronary artery in-stent restenosis (ISR). Mass spectrometry showed that high-mobility group box (HMGB) 2 level was higher in ISR than in non-ISR tissue from diabetic minipigs. We here investigated whether serum HMGB2 levels were related to ISR in coronary artery disease patients. The effect of HMGB2 was evaluated in mice with femoral artery wire injury and in human aortic smooth muscle cells. Approach and Results— From 2513 patients undergoing coronary artery intervention and follow-up angiography at ≈1 year, 262 patients were diagnosed with ISR, and 298 patients with no ISR were randomly included as controls. Serum HMGB2 levels were significantly higher in patients with ISR than in those without ISR and were associated with ISR severity. Multivariable logistic regression analysis showed that HMGB2 level was independently associated with ISR. In experiments, HMGB2 expression was increased in vascular tissue after injury. Perivascular HMGB2 administration promoted injury-induced neointimal hyperplasia in C57Bl/6 mice compared with in the control, whereas such pathophysiological features were attenuated in Hmgb2–/– mice. Mechanistically, HMGB2 enhanced neointimal hyperplasia in mice and proliferation and migration in human aortic smooth muscle cells by inducing reactive oxygen species through increased p47phox phosphorylation. Knocking down p47phox, however, inhibited HMGB2-induced effects in human aortic smooth muscle cells. Finally, HMGB2-induced effects were significantly declined in receptor of advanced glycation end products knockdown or deficient cells, but not in Toll-like receptor 4 knockdown or deficient cells. Conclusions— Serum HMGB2 levels were associated with ISR in patients. HMGB2 promoted neointimal hyperplasia in mice with arterial wire injury through reactive oxygen species activation.