Xinxin Liu

Geraniin Inhibits LPS-Induced THP-1 Macrophages Switching to M1 Phenotype via SOCS1/NF-κB Pathway

M1 macrophage polarization is proved to promote inflammation in atherosclerosis process. In this study, we evaluated the inhibitory effect of geraniin, a bioactive polyphenolic compound, on the LPS-induced switch of THP-1 macrophages to M1 phenotype, and we propose a molecular basis for its action. Flow cytometry analysis indicated that geraniin significantly inhibited LPS-induced M1 macrophage polarization. Geraniin downregulated the protein and the mRNA level of typical cytokines of M1 macrophage, including tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6), indicating that geraniin can suppress typical mediators of M1 macrophage at the transcriptional level. Moreover, geraniin inhibited LPS-induced reactive oxygen species (ROS) and nitric oxide (NO) production, as well as inducible nitric oxide synthase (iNOS) activity, in THP-1 macrophages. Furthermore, western blot analysis indicated that geraniin decreased both LPS-induced phosphorylation of NF-κB-p65 and NF-κB-p65 expression without affecting the level of IκB-α. This suggested that geraniin inhibited NF-κB, a transcription factor pivotal in the LPS-induced expression of pro-inflammatory genes and an important player in M1 macrophage polarization. Moreover, an electrophoretic mobility shift assay (EMSA) demonstrated that geraniin blocked the LPS-induced translocation of NF-κB to the nucleus. Moreover, we found that geraniin up-regulated the expression of SOCS1, an upstream regulator of NF-κB activation that can directly bind to NF-κB-p65 and downregulate it, thus inhibiting NF-κB activation. In conclusion, geraniin inhibits LPS-induced THP-1 macrophages switching to M1 phenotype through SOCS1/NF-κB pathway.

Nicorandil modulated macrophages activation and polarization via NF-κb signaling pathway

HIGHLIGHTSNicorandil could inhibit inflammation through regulating the M1/M2 status of macrophage.NF‐&kgr;b signaling pathway was a vital player in the regulation of macrophages phenotype.Nicorandil promoted the tube formation ability and VEGF expression in endothelial cells. ABSTRACT Nicorandil, a drug with both nitrate‐like and ATP‐sensitive potassium (KATP) channel‐activating properties, has been well demonstrated in various aspects of myocardial infarction (MI), especially in inhibiting cell apoptosis and increasing coronary flow. However, the role of nicorandil in regulating inflammation and angiogenesis following myocardial infarction is still unrevealed. In the present study, we explored the effect of nicorandil on macrophage phenotype transition and inflammation regulation and the potential underlying mechanisms. For the phenotype transition and phagocytosis ability of macrophages detection, flow cytometry analysis was used. The inflammation factors were measured with ELISA and qRT‐PCR. Western blot was used to assess the levels of NF‐&kgr;b and its target genes and VEGF expression. The tube formation ability of endothelial cells was examined on matrigel. We discovered that nicorandil can obviously inhibit the differentiation of monocytes into mature macrophages and decrease M1 phenotype transition both in peritoneal macrophages and cultured macrophage cell line in normal or hypoxia and serum deprivation (H/SD) conditions. Meanwhile, nicorandil can induce an anti‐inflammatory M2 phenotype. Thereby, nicorandil regulated macrophages switching to M1/M2 status. Our data further showed that NF‐&kgr;b and the expression of its target genes were pivotal players in the regulation of macrophages phenotype. Besides, we also showed that nicorandil can promote the tube formation and VEGF expression in endothelial cells. We concluded that nicorandil may serve as an effective modulator of NF‐&kgr;b signaling pathway during the pathogenesis of MI via regulating M1/M2 status and promoting angiogenesis.

Comparison of optical coherence tomography and intravascular ultrasound for evaluation of coronary lipid-rich atherosclerotic plaque progression and regression.

AIMS Compared with intravascular ultrasound (IVUS), optical coherence tomography (OCT) has relative merits and demerits for detecting plaque characteristics. It remains unknown whether the IVUS and OCT evaluations of plaque progression/regression are consistent. We sought to analyse the correlations between IVUS and OCT evaluations of plaques at single time points, and compare temporal changes in the IVUS and OCT data. METHODS AND RESULTS Eighty-eight lipid-rich plaques from 65 patients with coronary artery disease were analysed with IVUS and OCT at baseline and 12-month follow-up. Fibrous cap thickness on OCT was negatively correlated with total atheroma volume on IVUS (r = -0.28, P = 0.009), but not with percent atheroma volume (P = 0.84). Changes on OCT were not significantly correlated with changes on IVUS. Plaques that showed progression, regression, or no change on IVUS showed no differences in terms of changes in the OCT parameters fibrous cap thickness (P = 0.199), maximum lipid core arc (P = 0.755), mean lipid core arc (P = 0.936), and lipid index (P = 0.91). The incidence of thin-cap fibroatheroma (TCFA) was similar among the above three plaque groups at baseline (P = 0.79) and follow-up (P = 0.609). CONCLUSION Although fibrous cap thickness on OCT was negatively correlated with plaque size on IVUS at single time points, changes in OCT parameters were not correlated with changes in IVUS measures over time. Lesion progression/regression on IVUS was not associated with changes in OCT parameters (fibrous cap thickness, lipid core arc, lipid index, and TCFA).

Adipose‐Derived Exosomes Exert Proatherogenic Effects by Regulating Macrophage Foam Cell Formation and Polarization

Background Obesity is causally associated with atherosclerosis, and adipose tissue (AT)–derived exosomes may be implicated in the metabolic complications of obesity. However, the precise role of AT‐exosomes in atherogenesis remains unclear. We herein aimed to assess the effect of AT‐exosomes on macrophage foam cell formation and polarization and subsequent atherosclerosis development. Methods and Results Four types of exosomes isolated from the supernatants of ex vivo subcutaneous AT and visceral AT (VAT) explants that were derived from wild‐type mice and high‐fat diet (HFD)–induced obese mice were effectively taken up by RAW264.7 macrophages. Both treatment with wild‐type VAT exosomes and HFD‐VAT exosomes, but not subcutaneous AT exosomes, markedly facilitated macrophage foam cell generation through the downregulation of ATP‐binding cassette transporter (ABCA1 and ABCG1)–mediated cholesterol efflux. Decreased expression of liver X receptor‐α was also observed. Among the 4 types of exosomes, only HFD‐VAT exosomes significantly induced M1 phenotype transition and proinflammatory cytokine (tumor necrosis factor α and interleukin 6) secretion in RAW264.7 macrophages, which was accompanied by increased phosphorylation of NF‐κB‐p65 but not the cellular expression of NF‐κB‐p65 or IκB‐α. Furthermore, systematic intravenous injection of HFD‐VAT exosomes profoundly exacerbated atherosclerosis in hyperlipidemic apolipoprotein E–deficient mice, as indicated by the M1 marker (CD16/32 and inducible nitric oxide synthase)–positive areas and the Oil Red O/Sudan IV–stained area, without affecting the plasma lipid profile and body weight. Conclusions This study demonstrated a proatherosclerotic role for HFD‐VAT exosomes, which is exerted by regulating macrophage foam cell formation and polarization, indicating a novel link between AT and atherosclerosis in the context of obesity.

Cables1 Inhibits Proliferation and Induces Senescence by Angiotensin II via a p21-Dependent Pathway in Human Umbilical Vein Endothelial Cells

Cables1 (Cdk5 and Abl enzyme substrate 1) is a vital cell cycle regulator and a candidate tumor suppressor that negatively regulates cell growth by inhibiting cyclin-dependent kinases. Here, we report on the critical role of the Cables1/p21 pathway, which inhibits cell proliferation and induces cell senescence in human umbilical vein endothelial cells. Moreover, we confirmed that silencing of Cables1 promoted cell proliferation as well as increased resistance to angiotensin II-induced senescence, at least in part, by altering Cables1 activation. We further demonstrated that knockdown of p21 reverses Cables1-mediated cell growth inhibition and cell senescence. Taken together, these results suggest that the Cables1/p21 pathway has a strong effect on the induction of cell senescence and inhibition of cell growth, and acts as a novel regulatory mechanism in which p21 is probably one of several downstream effector molecules to mediate Cables1.

Plasma trimethylamine N-oxide is associated with vulnerable plaque characteristics in CAD patients as assessed by optical coherence tomography

BACKGROUND Plaque vulnerability indicates the risk of a cardiovascular event. In the present study, we sought to analyze the relationship between trimethylamine N-oxide (TMAO), a gut microbiota metabolite from dietary phosphatidylcholine, and vulnerable plaque characteristics in patients with coronary artery disease (CAD). METHODS One hundred eighty non-culprit plaques from 90 patients with ACS or with stable angina were assessed by optical coherence tomography (OCT). The plasma TMAO levels were measured using rapid resolution liquid chromatography quadrupole time-of-flight mass spectrometry (RRLC-QTOF/MS). RESULTS Patients were divided into two groups (high TMAO group and low TMAO group) according to the median plasma TMAO level (114.73 μg/L). The non-culprit plaques in the high TMAO group exhibited a thinner fibrous cap thickness (FCT) (65.97 ± 25.89 vs. 93.0 ± 28.28 μm, P < 0.001), higher frequency of microvessels (75.6% vs. 31.1%, P < 0.001, per-patient) and increased incidence of thin-cap fibroatheroma (TCFA) (69.2% vs. 18.4%, P < 0.001, per-patient) compared with the low TMAO group. Moreover, the level of TMAO was negatively associated with FCT (r = -0.418, P < 0.001). Furthermore, multivariate regression analysis results showed that TMAO (OR: 7.455, 95% CI: 2.753-20.189, P < 0.001) had a significant association with TCFA, with a cut-off point of 118.34 μg/L, specificity of 72.6% and sensitivity of 79.5% in predicting the prevalence of TCFA. CONCLUSIONS In conclusion, these findings suggest that the level of TMAO is significantly correlated with the incidence of TCFA. New biomarkers acquired through non-invasive means, such as TMAO, offer the potential to improve risk stratification and clinical management in patients with CAD.

Relation between baseline plaque features and subsequent coronary artery remodeling determined by optical coherence tomography and intravascular ultrasound

Atherosclerosis often leads to myocardial infarction and stroke. We examined the influence of baseline plaque characteristics on subsequent vascular remodeling in response to changes in plaque size. Using optical coherence tomography (OCT) and intravascular ultrasound (IVUS), we examined 213 plaques from 138 patients with acute coronary syndrome at baseline and repeated IVUS at the 12-month follow-up. The change in external elastic membrane (EEM) area for each 1 mm2 change in plaque area (i.e., the slope of the regression line) was calculated as a measure of vascular remodeling capacity. In plaques with static positive remodeling, the slope was smaller than in plaques without static positive remodeling. In addition, the slope of the regression line for lesions with a large plaque burden was much smaller than that for lesions with a small plaque burden. Multivariate linear regression analysis showed that diabetes, calcification and static positive remodeling were inversely and independently associated with the level of change in EEM area/change in plaque area. Lesions with a large plaque burden, calcifications or static positive remodeling had less remodeling capacity, and calcification and static positive remodeling were independent predictors of reduced subsequent remodeling. Therefore, calcifications and static positive remodeling could be used as morphological biomarkers to predict decreased subsequent arterial remodeling.

Geraniin protects bone marrow‑derived mesenchymal stem cells against hydrogen peroxide‑induced cellular oxidative stress in vitro

Administration of bone marrow-derived mesenchymal stem cells (MSCs) has emerged as a potential therapeutic approach for the treatment of myocardial infarction (MI). However, the increase in reactive oxygen species (ROS) in ischemic cardiac tissue compromises the survival of transplanted MSCs, thus resulting in limited therapeutic efficiency. Therefore, strategies that attenuate oxidative stress-induced damage and enhance MSC viability are required. Geraniin has been reported to possess potent antioxidative activity and exert protective effects on numerous cell types under certain conditions. Therefore, geraniin may be considered a potential drug used to modulate MSC-based therapy for MI. In the present study, MSCs were pretreated with geraniin for 24 h and were exposed to hydrogen peroxide (H2O2) for 4 h. Cell apoptosis, intracellular ROS levels and mitochondrial membrane potential were measured using Annexin V-fluorescein isothiocyanate/ propidium iodide staining, the 2′,7′-dichlorodihydrofluorescein diacetate fluorescent probe and the membrane permeable dye JC-1, respectively. Glutathione and malondialdehyde levels were also investigated. The expression levels of apoptosis-associated proteins and proteins of the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway were analyzed by western blotting. The results demonstrated that geraniin could significantly attenuate H2O2-induced cell damage by promoting MSC survival, reducing cellular ROS production and maintaining mitochondrial function. Furthermore, geraniin modulated the expression levels of phosphorylated-Akt in a time- and dose-dependent manner. The cytoprotective effects of geraniin were suppressed by LY294002, a specific PI3K inhibitor. In conclusion, the present study revealed that geraniin protects MSCs from H2O2-induced oxidative stress injury via the PI3K/Akt pathway. These findings indicated that cotreatment of MSCs with geraniin may optimize therapeutic efficacy for the clinical treatment of MI.

Relationship between serum angiopoietin-like protein 2 and plaque vulnerability in patients with coronary artery disease and diabetes

AIMS Obesity is characterized by low-grade inflammation state and excessive inflammatory cytokine production of adipose tissue. Angiopoietin-like protein 2 (ANGPTL2), a novel proinflammatory adipokine, has recently been suggested to be involved in the pathogenesis of atherosclerosis in animal studies. However, no data regarding the relationship between ANGPTL2 and morphologic characteristics of coronary plaques in humans are available. The aim of the current study was to investigate the in vivo association between serum ANGPTL2 level and plaque vulnerability in patients with coronary artery disease (CAD) and diabetes. METHODS AND RESULTS 72 consecutive patients with clinically proven CAD and diabetes were enrolled between October 2013 and December 2014. Circulating ANGPTL2 concentration was measured using a human ANGPTL2 sandwich enzyme-linked immunosorbent assay (ELISA) kit. The morphologic characteristics of non-culprit lipid-rich plaques were assessed by optical coherence tomography. Fibrous cap thickness was significantly and negatively correlated with serum ANGPTL2 levels (r = -0.29, P = 0.005). A significant and positive correlation was observed between mean lipid core arc and serum ANGPTL2 concentration (r = 0.32, P = 0.01). In addition, levels of serum ANGPTL2 were significantly higher in patients with thin-cap fibroatheroma (TCFA) than those without TCFA (P < 0.001). Multivariate logistic regression analysis showed that a higher serum ANGPTL2 concentration was a powerful predictor of TCFA (odds ratio: 3.18, P = 0.002). CONCLUSION Serum ANGPTL2 level is significantly associated with plaque vulnerability in patients with CAD and diabetes. Systemic ANGPTL2 comprises an inflammatory adipokine that links the adipose tissue and coronary plaque.