Atherosclerotic Plaque Inflammation Research Articles

Myeloid Mineralocorticoid Receptor Transcriptionally Regulates P-Selectin Glycoprotein Ligand-1 and Promotes Monocyte Trafficking and Atherosclerosis.

MR (mineralocorticoid receptor) activation associates with increased risk of cardiovascular ischemia while MR inhibition reduces cardiovascular-related mortality and plaque inflammation in mouse atherosclerosis. MR in myeloid cells (My-MR) promotes inflammatory cell infiltration into injured tissues and atherosclerotic plaque inflammation by unclear mechanisms. Here, we examined the role of My-MR in leukocyte trafficking and the impact of sex. We confirm in vivo that My-MR deletion (My-MR-KO) in ApoE-KO mice decreased plaque size. Flow cytometry revealed fewer plaque macrophages with My-MR-KO. By intravital microscopy, My-MR-KO significantly attenuated monocyte slow-rolling and adhesion to mesenteric vessels and decreased peritoneal infiltration of myeloid cells in response to inflammatory stimuli in male but not female mice. My-MR-KO mice had significantly less PSGL1 (P-selectin glycoprotein ligand 1) mRNA in peritoneal macrophages and surface PSGL1 protein on circulating monocytes in males. In vitro, MR activation with aldosterone significantly increased PSGL1 mRNA only in monocytes from MR-intact males. Similarly, aldosterone induced, and MR antagonist spironolactone inhibited, PSGL1 expression in human U937 monocytes. Mechanistically, aldosterone stimulated MR binding to a predicted MR response element in intron-1 of the PSGL1 gene by ChIP-qPCR. Reporter assays demonstrated that this PSGL1 MR response element is necessary and sufficient for aldosterone-activated, MR-dependent transcriptional activity. These data identify PSGL1 as a My-MR target gene that drives leukocyte trafficking to enhance atherosclerotic plaque inflammation. These novel and sexually dimorphic findings provide insight into increased ischemia risk with MR activation, cardiovascular protection in women, and the role of MR in atherosclerosis and tissue inflammation.

Gadolinium enhancement of atherosclerotic plaque in the intracranial artery

ABSTRACT Background: Gadolinium enhancement on high resolution magnetic resonance imaging (HR-MRI) has been considered a sign of instability and inflammation of intracranial atherosclerotic plaques. Our research objective was to explore the relationship between the extent of plaque enhancement (PE), the degree of intracranial artery stenosis, and acute ischemic stroke events. Methods: HR-MRI was performed in 91 patients with intracranial vascular stenosis to determine the existence and intensity of PE. Results: Among 91 patients enrolled in the trial, there were 43 patients in the acute/subacute group (≤1 month from ischemic stroke event), 15 patients in the chronic group (>1 month from ischemic stroke event), and 33 patients in the non-culprit plaques group (no ischemic stroke event). A total of 105 intracranial atherosclerotic plaques were detected in 91 patients. 14 (13.3%) were mild-stenosis plaques, 22 (21.0%) were moderate-stenosis plaques, and 69 (65.7%) were severe-stenosis plaques. There were 12 (11.4%), 18 (17.1%), and 75 (71.4%) plaques in the non-enhanced plaque group, the mild-enhancement group, and the significant-enhancement group, respectively. The degree of PE among the acute/subacute group, the chronic group, and the non-culprit plaque group had a significant difference (P = 0.005). Enhanced plaques were more often observed in culprit plaques (acute/subacute group and chronic group) than non-culprit plaques (96.7% vs 77.3%). Non-enhanced plaques were more often observed in non-culprit plaques than culprit plaques (acute/subacute group and chronic group) (22.7% vs 3.3%). And 36.6% of the enhanced plaques were non-culprit plaques. After performing univariate and multivariate logistic regression analysis, the results showed that strong plaque enhancement (P = 0.025, odds ratio [OR] 3.700, 95% confidence interval [95% CI] 1.182–11.583) and severe stenosis (P = 0.008, OR 4.393, 95%CI 1.481–13.030) were significantly associated with acute ischemic events. Conclusion: Enhanced plaques were more often observed in culprit plaques, and non-enhanced plaques were more often observed in non-culprit plaques. Moreover, significant plaque enhancement and severe ICAS were closely associated with acute ischemic events.

Features of interleukin-19 production in patients with atherosclerosis

Objective. To study the features of local and systemic production of interleukin-19 in patients with atherosclerosis.Material and Methods. The study comprised a total of 46 patients (26 women and 20 men) treated for arterial hypertension in the therapeutic department of Republican Clinical Hospital named after G.Y. Remishevskaya. The mean age of subjects was 63.4 ± 3.2 years. The control group included 40 patients (23 women and 17 men aged 44.7 ± 5.5 years) who did not have atherosclerosis. Samples of atherosclerotic plaques and venous blood were examined. Atherosclerotic plaques were obtained by endarterectomy and then subjected to homogenization followed by enzymatic hydrolysis for 1 h at 37 °C with collagenase IV in the presence of proteinase III inhibitors. The serum levels of cytokines (in the control group and in patients with atherosclerosis) and in the atherosclerotic plaque homogenate (in patients with atherosclerosis) were determined by ELISA. To assess the cytokine-producing capacity of blood leukocytes and white blood cells isolated from atherosclerotic plaques, spontaneous and phytohemagglutinin (PHA)-induced cytokine production was determined when the cells were cultured in RPMI-1640.Results. The serum levels of IL-19 did not significantly differ between the patients with atherosclerosis and the control group. A statistically significant two-fold increase in the spontaneous expression of IL-19 by blood leukocytes was observed in the group of patients with atherosclerosis in comparison with the control group. When comparing the contents of IL-19 in blood serum and atherosclerotic plaque homogenate in patients with atherosclerosis, no statistically significant differences were found (p = 0.182). The level of PHA-induced IL-19 production by the atherosclerotic plaque white blood cells was significantly lower than that of blood leucocytes.Conclusion. The study showed that the reserve capacity for IL-19 synthesis in the atherosclerotic plaque white blood cells decreases leading to the progression of inflammation. The obtained results suggest that IL-19 plays the anti-atherogenic role and its production is involved in the maintaining the mechanisms for down-regulation of inflammation in atherosclerotic plaques.

18F-ASEM Imaging for Evaluating Atherosclerotic Plaques Linked to α7-Nicotinic Acetylcholine Receptor.

BackgroundAtherosclerosis is a chronic vascular inflammatory procedure alongside with lipid efflux disorder and foam cell formation. α7-Nicotinic acetylcholine receptor (α7nAChR) is a gated-calcium transmembrane channel widely expressed in neuron and non-neuron cells, such as monocytes and macrophages, activated T cells, dendritic cells, and mast cells. 18F-ASEM is an inhibitor targeted to α7nAChR that had been successfully applied in nervous system diseases. Previous studies had highlighted that α7nAChR was related to the emergency of vulnerable atherosclerotic plaques with excess inflammation cells. Thus, 18F-ASEM could be a complementary diagnostic approach to atherosclerotic plaques.Materials and MethodsThe synthesis of ASEM precursor and 18F-labeling had been performed successfully. We had established the ApoE–/– mice atherosclerotic plaques model (fed with western diet) and New Zealand rabbits atherosclerotic models (balloon-sprained experiment and western diet). After damage of endothelial cells and primary plaque formation, 18F-ASEM imaging of atherosclerotic plaques linked to α7nAChR had been conducted. In vivo micro-PET/CT imaging of ApoE–/– mice and the control group was performed 1 h after injection of 18F-ASEM (100–150 μCi); PET/CT imaging for rabbits with atherosclerotic plaques and control ones was also performed. Meanwhile, we also conducted CT scan on the abdominal aorta of these rabbits. After that, the animals were sacrificed, and the carotid and abdominal aorta were separately taken out for circular sections. The paraffin-embedded specimens were sectioned with 5 μm thickness and stained with hematoxylin–eosin (H&E) and oil red.ResultsIn vivo vessel binding of 18F-ASEM and α7nAChR expression in the model group with atherosclerosis plaques was significantly higher than that in the control group. PET/CT imaging successfully identified the atherosclerotic plaques in ApoE–/– mice and model rabbits, whereas no obvious signals were detected in normal mice or rabbits. Compared with 18F-FDG, 18F-ASEM had more significant effect on the early monitoring of inflammation in carotid atherosclerotic plaques of ApoE–/– mice and model rabbits. 18F-ASEM had relatively more palpable effect on the imaging of abdominal aorta with atherosclerosis in rabbits. H&E and oil red staining identified the formation of atherosclerotic plaques in model animals, which provided pathological basis for the evaluation of imaging effects.ConclusionWe first confirmed 18F-ASEM as radiotracer with good imaging properties for precise identification of atherosclerotic diseases.

MiR-100-5p in human umbilical cord mesenchymal stem cell-derived exosomes mediates eosinophilic inflammation to alleviate atherosclerosis via the FZD5/Wnt/β-catenin pathway.

Exosomes derived from human umbilical cord mesenchymal stem cells (hUCMSC-Ex) play important roles in immune and inflammation diseases. However, the role of hUCMSC-Ex in atherosclerosis has not been elucidated. In this study, the isolated exosomes were identified by transmission electron microscopy and nanoparticle tracking analysis. Exosome marker protein levels were increased in the hUCMSC-Ex compared with those in hUCMSC suspension, indicating that exosomes were successfully isolated from hUCMSCs. Furthermore, eosinophils were treated with oxidized low-density lipoprotein (ox-LDL) to construct inflammation model and then incubated with hUCMSC-Ex derived from hUCMSCs which were transfected with miR-100-5p mimic or miR-100-5p inhibitor. We found that hUCMSC-Ex increased miR-100-5p expression, inhibited cell migration, promoted cell apoptosis, and reduced inflammatory cytokine levels in ox-LDL-treated eosinophils, and miR-100-5p overexpression in hUCMSCs enhanced these effects, while miR-100-5p inhibition reversed these effects. Moreover, frizzled 5 (FZD5) was a target gene of miR-100-5p. FZD5 overexpression reversed the inhibitory effects of hUCMSC-Ex-miR-100-5p on cell progression and inflammation in eosinophils. Additionally, hUCMSC-Ex-miR-100-5p decreased the expression of cyclin D1 and β-catenin proteins. Wnt/β-catenin pathway activator BML-284 effectively reversed the effects of hUCMSC-Ex-miR-100-5p on cell progression and inflammation in eosinophils. ApoE-/- mice were fed with high-fat diet to construct an atherosclerosis mice model, and hUCMSC-Ex was injected into mice. hUCMSC-Ex reduced atherosclerotic plaque area and inflammation response in atherosclerosis mice. This study demonstrates that hUCMSC-Ex-miR-100-5p inhibits cell progression and inflammatory response in eosinophils via the FZD5/Wnt/β-catenin pathway, thereby alleviating atherosclerosis progression.

Ultra-selective carbon nanotubes for photoacoustic imaging of inflamed atherosclerotic plaques.

Disruption of vulnerable atherosclerotic plaques often leads to myocardial infarction and stroke, the leading causes of morbidity and mortality in the United States. A diagnostic method that detects high-risk atherosclerotic plaques at early stages could prevent these sequelae. The abundance of immune cells in the arterial wall, especially inflammatory Ly-6Chi monocytes and foamy macrophages, is indicative of plaque‎ inflammation, and may be associated with plaque vulnerability. Hence, we sought to develop a new method that specifically targets these immune cells to offer clinically-relevant diagnostic information about cardiovascular disease. We combine ultra-selective nanoparticle targeting of Ly-6Chi monocytes and foamy macrophages with clinically-viable photoacoustic imaging (PAI) in order to precisely and specifically image inflamed plaques ex vivo in a mouse model that mimics human vulnerable plaques histopathologically. Within the plaques, high-dimensional single-cell flow cytometry (13-parameter) showed that our nanoparticles were almost-exclusively taken up by the Ly-6Chi monocytes and foamy macrophages that heavily infiltrate plaques. PAI identified inflamed atherosclerotic plaques that display ~6-fold greater signal compared to controls (P<0.001) six hours after intravenous injection of ultra-selective carbon nanotubes, with in vivo corroboration via optical imaging. Our highly selective strategy may provide a targeted, non-invasive imaging strategy to accurately identify and diagnose inflamed atherosclerotic lesions.

Pharmacological inhibition of fatty acid oxidation reduces atherosclerosis progression by suppression of macrophage NLRP3 inflammasome activation

BackgroundInflammation is a key process during atherosclerotic lesion development and propagation. Recent evidence showed clearly that especially the inhibition of interleukin (IL)-1β reduced atherosclerotic adverse events in human patients. Fatty acid oxidation (FAO) was previously demonstrated to interact with the NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) pathway which is required for mature IL-1β secretion. To understand possible anti-inflammatory properties of FAO inhibition, we tested the effect of pharmacological FAO inhibition using the inhibitor for long-chain 3-ketoacyl coenzyme A thiolase trimetazidine on atherosclerotic plaque development and inflammation. Experimental ApproachThe effect of FAO inhibition was determined in LDL-R−/− male mice on a C57/BL6 background. In vitro effects of trimetazidine treatment were analyzed in human umbilical vein endothelial cells and human monocyte derived macrophages. Key ResultsWe were able to demonstrate that inhibition of FAO reduced atherosclerotic plaque growth. We did not find direct anti-inflammatory properties of trimetazidine in endothelial cells or macrophages in vitro. However, we found that the activation of the NLRP3 system and the secretion of IL-1β were significantly reduced in macrophages after FAO inhibition. These results were confirmed in atherosclerotic lesions of mice treated with trimetazidine as they showed a significant reduction of IL-1β and cleaved caspase-1 in the atherosclerotic lesion as well as of IL-1β and IL-18 in the circulation. ConclusionOverall, we therefore suggest that the main mechanism of reducing inflammation of trimetazidine and FAO inhibition is the reduction of the NLRP-3 activation leading to reduced levels of the proinflammatory cytokine IL-1β.

CD200 is an atheroprotective immune checkpoint.

The CD200 inhibitory immune checkpoint promotes arterial homeostasis and reduces atherosclerotic plaque progression and inflammation in mice by limiting the excessive supply, recruitment and activation of monocytes and macrophages during atherogenesis, according to a new study.

Reshaping of the gastrointestinal microbiome alters atherosclerotic plaque inflammation resolution in mice

Since alterations in the intestinal microbiota may induce systemic inflammation and polarization of macrophages to the M1 state, the microbiome role in atherosclerosis, an M1-driven disease, requires evaluation. We aimed to determine if antibiotic (Abx) induced alterations to the intestinal microbiota interferes with atherosclerotic plaque inflammation resolution after lipid-lowering in mice. Hyperlipidemic Apoe−/− mice were fed a western diet to develop aortic atherosclerosis with aortas then transplanted into normolipidemic wild-type (WT) mice to model clinically aggressive lipid management and promote atherosclerosis inflammation resolution. Gut microbial composition pre and post-transplant was altered via an enteral antibiotic or not. Post aortic transplant, after Abx treatment, while plaque size did not differ, compared to Apoe−/− mice, Abx– WT recipient mice had a 32% reduction in CD68-expressing cells (p = 0.02) vs. a non-significant 12% reduction in Abx+ WT mice. A trend toward an M1 plaque CD68-expresing cell phenotype was noted in Abx+ mice. By 16S rRNA sequence analysis, the Abx+ mice had reduced alpha diversity and increased Firmicutes/Bacteroidetes relative abundance ratio with a correlation between gut Firmicutes abundance and plaque CD68-expressing cell content (p < 0.05). These results indicate that in a murine atherosclerotic plaque inflammation resolution model, antibiotic-induced microbiome perturbation may blunt the effectiveness of lipid-lowering to reduce the content of plaque inflammatory CD68-expressing cells.

Lipoprotein-associated Phospholipase A2: Current Trends in Invitro Diagnostics

Lipoprotein-associated phospholipase A2 is an imminent reliable precise biomarker for vascular inflammation involved in the development of unstable plaques in cardiovascular diseases. The atherosclerotic plaque formation, inflammation and rupture of arterial vessels lead to heart attacks and strokes in most of the cases. The vessel-specific inflammatory enzyme, Lipoprotein-associated phospholipase A2 shoot ups in response to the rupture of arterial vessels having atherosclerotic plaques. The accurate measurement of Lipoprotein-associated phospholipase A2 envisages the individual risk of a patient and the treatment can be customized based on the result.

Association of Inflammatory Metabolic Activity of Psoas Muscle and Acute Myocardial Infarction: A Preliminary Observational Study with 18F-FDG PET/CT.

Inflamed skeletal muscle promotes chronic inflammation in atherosclerotic plaques, thereby contributing to the increased risk of coronary artery disease (CAD). In this study, we evaluated the metabolic activity of psoas muscle, using 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), and its association with carotid artery inflammation and acute myocardial infarction (AMI). In total, 90 participants (32 AMI, 33 chronic stable angina (CSA), and 25 control) were enrolled in this prospective study. Metabolic activity of skeletal muscle (SM) was measured by using maximum standardized uptake value (SUVmax) of psoas muscle, and corresponding psoas muscle area (SM area) was also measured. Carotid artery inflammation was evaluated by using the target-to background ratio (TBR) of carotid artery. SM SUVmax was highest in AMI, intermediate in CSA, and lowest in control group. SM SUVmax was significantly correlated with carotid artery TBR and systemic inflammatory surrogate markers. Furthermore, SM SUVmax was independently associated with carotid artery TBR and showed better predictability than SM area for the prediction of AMI. Metabolic activity of psoas muscle assessed by 18F-FDG PET/CT was associated with coronary plaque vulnerability and synchronized with the carotid artery inflammation in the participants with CAD. Furthermore, it may also be useful to predict AMI.

In vivo MRI detection of intraplaque macrophages with biocompatible silica-coated iron oxide nanoparticles in murine atherosclerosis.

Identification of a vulnerable atherosclerotic plaque before rupture is an unmet clinical need. Integrating nanomedicine with multimodal imaging has the potential to precisely detect biological processes in atherosclerosis. We synthesized silica-coated iron oxide nanoparticles (SIONs) coated with rhodamine B isothiocyanate and polyethylene glycol and investigated their feasibility in the detection of macrophages in inflamed atherosclerotic plaques of apolipoprotein E-deficient (ApoE-/-) mice via magnetic resonance (MR) and fluorescence reflectance (FR) imaging. In vitro cellular uptake of SIONs was assessed in macrophages using confocal laser scanning microscopy (CLSM). In vivo MR imaging was performed 24 h after SION injection via the tail vein in 26-week-old ApoE-/- mice fed a high-cholesterol diet (HCD). We also performed FR imaging of the extracted aortas from four different mice: two normal-diet-fed C57BL/6 mice injected with saline or 10 mg/kg SIONs and two HCD-fed ApoE-/- mice injected with 5 or 10 mg/kg SIONs. The harvested aortas were cryosectioned and stained with immunohistochemical staining. The CLSM images at 24 h after incubation showed efficient uptake of SIONs by macrophages, with no evidence of cytotoxicity. The in vivo and ex vivo MR and FR images demonstrated SION deposition in the atheroma. Upon immunohistochemical staining of the aorta, CLSM images revealed colocalization of macrophages and SIONs in the atherosclerotic plaque. These results demonstrate that polyethylene glycosylated SIONs could be a highly effective method to identify macrophage activity in atherosclerotic plaques as a multimodal imaging agent.

The Anti-atherogenic Role of Exercise Is Associated With the Attenuation of Bone Marrow-Derived Macrophage Activation and Migration in Hypercholesterolemic Mice.

An early event in atherogenesis is the recruitment and infiltration of circulating monocytes and macrophage activation in the subendothelial space. Atherosclerosis subsequently progresses as a unresolved inflammatory disease, particularly in hypercholesterolemic conditions. Although physical exercise training has been a widely accepted strategy to inhibit atherosclerosis, its impact on arterial wall inflammation and macrophage phenotype and function has not yet been directly evaluated. Thus, the aim of this study was to investigate the effects of aerobic exercise training on the inflammatory state of atherosclerotic lesions with a focus on macrophages. Hypercholesterolemic LDL-receptor-deficient male mice were subjected to treadmill training for 8 weeks and fed a high-fat diet. Analyses included plasma lipoprotein and cytokine levels; aortic root staining for lipids (oil red O); macrophages (CD68, MCP1 and IL1β); oxidative (nitrotyrosine and, DHE) and endoplasmic reticulum (GADD) stress markers. Primary bone marrow-derived macrophages (BMDM) were assayed for migration activity, motility phenotype (Rac1 and F-actin) and inflammation-related gene expression. Plasma levels of HDL cholesterol were increased, while levels of proinflammatory cytokines (TNFa, IL1b, and IL6) were markedly reduced in the exercised mice. The exercised mice developed lower levels of lipid content and inflammation in atherosclerotic plaques. Additionally, lesions in the exercised mice had lower levels of oxidative and ER stress markers. BMDM isolated from the exercised mice showed a marked reduction in proinflammatory cytokine gene expression and migratory activity and a disrupted motility phenotype. More importantly, bone marrow from exercised mice transplanted into sedentary mice led to reduced atherosclerosis in the recipient sedentary mice, thus suggesting that epigenetic mechanisms are associated with exercise. Collectively, the presented data indicate that exercise training prevents atherosclerosis by inhibiting bone marrow-derived macrophage recruitment and activation.

Inflammation of carotid plaques and risk of cerebrovascular events.

Carotid atherosclerotic plaques represent a risk for ischemic stroke. The data indicate that the risk for distal embolization from atherosclerotic lesions in internal carotid arteries is not related only to the degree of stenosis but also to the composition of plaques. The stability of atherosclerotic plaque depends on the thickness of the fibrous cap and plaque hemorrhage. Recent research indicated that the inflammatory activity of atherosclerotic lesions is pivotal in the progression of atherosclerotic plaques. It also promotes the development of unstable atherosclerotic lesions and is related to thromboembolic cerebrovascular complications. Inflammation destabilizes atherosclerotic plaques through the degradation of their fibrotic structure. Inflammation of atherosclerotic plaques was confirmed by histopathologic findings and levels of circulating inflammatory markers which were correlated to the intensity of the inflammation in atherosclerotic lesions. Recently, new techniques like fluorodeoxyglucose positron emission tomography (18-FDG PET) were developed for the identification of inflammation of atherosclerotic lesions in the vessel wall in vivo. Systemic inflammatory markers, particularly interleukins, tumor necrosis factor-alpha and metalloproteinases were shown to be related to the intensity of the inflammatory process in atherosclerotic lesions and the cerebrovascular events. Identification of inflamed atherosclerotic plaques may help to identify unstable atherosclerotic lesions and subjects at high risk for cerebrovascular incidents who need intensive preventive measures including anti-inflammatory medication.

Antibody-Mediated Inhibition of CTLA4 Aggravates Atherosclerotic Plaque Inflammation and Progression in Hyperlipidemic Mice.

T cell-driven inflammation plays a critical role in the initiation and progression of atherosclerosis. The co-inhibitory protein Cytotoxic T-Lymphocyte Associated protein (CTLA) 4 is an important negative regulator of T cell activation. Here, we studied the effects of the antibody-mediated inhibition of CTLA4 on experimental atherosclerosis by treating 6–8-week-old Ldlr−/− mice, fed a 0.15% cholesterol diet for six weeks, biweekly with 200 μg of CTLA4 antibodies or isotype control for six weeks. 18F-fluorodeoxyglucose Positron Emission Tomography—Computed Tomography showed no effect of the CTLA4 inhibition of activity in the aorta, spleen, and bone marrow, indicating that monocyte/macrophage-driven inflammation was unaffected. Correspondingly, flow cytometry demonstrated that the antibody-mediated inhibition of CTLA4 did not affect the monocyte populations in the spleen. αCTLA4 treatment induced an activated T cell profile, characterized by a decrease in naïve CD44−CD62L+CD4+ T cells and an increase in CD44+CD62L− CD4+ and CD8+ T cells in the blood and lymphoid organs. Furthermore, αCTLA4 treatment induced endothelial activation, characterized by increased ICAM1 expression in the aortic endothelium. In the aortic arch, which mainly contained early atherosclerotic lesions at this time point, αCTLA4 treatment induced a 2.0-fold increase in the plaque area. These plaques had a more advanced morphological phenotype and an increased T cell/macrophage ratio, whereas the smooth muscle cell and collagen content decreased. In the aortic root, a site that contained more advanced plaques, αCTLA4 treatment increased the plaque T cell content. The short-term antibody-mediated inhibition of CTLA4 thus accelerated the progression of atherosclerosis by inducing a predominantly T cell-driven inflammation, and resulted in the formation of plaques with larger necrotic cores and less collagen. This indicates that existing therapies that are based on αCTLA4 antibodies may promote CVD development in patients.

Early modulation of macrophage ROS-PPAR\u03b3-NF-\u03baB signalling by sonodynamic therapy attenuates neointimal hyperplasia in rabbits

Disruption of re-endothelialization and haemodynamic balance remains a critical side effect of drug-eluting stents (DES) for preventing intimal hyperplasia. Previously, we found that 5-aminolevulinic acid-mediated sonodynamic therapy (ALA-SDT) suppressed macrophage-mediated inflammation in atherosclerotic plaques. However, the effects on intimal hyperplasia and re-endothelialization remain unknown. In this study, 56 rabbits were randomly assigned to control, ultrasound, ALA and ALA-SDT groups, and each group was divided into two subgroups (n = 7) on day 3 after right femoral artery balloon denudation combined with a hypercholesterolemic diet. Histopathological analysis revealed that ALA-SDT enhanced macrophage apoptosis and ameliorated inflammation from day 1. ALA-SDT inhibited neointima formation without affecting re-endothelialization, increased blood perfusion, decreased the content of macrophages, proliferating smooth muscle cells (SMCs) and collagen but increased elastin by day 28. In vitro, ALA-SDT induced macrophage apoptosis and reduced TNF-α, IL-6 and IL-1β via the ROS-PPARγ-NF-κB signalling pathway, which indirectly inhibited human umbilical artery smooth muscle cell (HUASMC) proliferation, migration and IL-6 production. ALA-SDT effectively inhibits intimal hyperplasia without affecting re-endothelialization. Hence, its clinical application combined with bare-metal stent (BMS) implantation presents a potential strategy to decrease bleeding risk caused by prolonged dual-antiplatelet regimen after DES deployment.

S100A9-RAGE Axis Accelerates Formation of Macrophage-Mediated Extracellular Vesicle Microcalcification in Diabetes Mellitus.

Vascular calcification is a cardiovascular risk factor and accelerated in diabetes mellitus. Previous work has established a role for calcification-prone extracellular vesicles in promoting vascular calcification. However, the mechanisms by which diabetes mellitus provokes cardiovascular events remain incompletely understood. Our goal was to identify that increased S100A9 promotes the release of calcification-prone extracellular vesicles from human macrophages in diabetes mellitus. Approach and Results: Human primary macrophages exposed to high glucose (25 mmol/L) increased S100A9 secretion and the expression of receptor for advanced glycation end products (RAGE) protein. Recombinant S100A9 induced the expression of proinflammatory and osteogenic factors, as well as the number of extracellular vesicles with high calcific potential (alkaline phosphatase activity, P<0.001) in macrophages. Treatment with a RAGE antagonist or silencing with S100A9 siRNA in macrophages abolished these responses, suggesting that stimulation of the S100A9-RAGE axis by hyperglycemia favors a procalcific environment. We further showed that an imbalance between Nrf-2 (nuclear factor 2 erythroid related factor 2) and NF-κB (nuclear factor-κB) pathways contributes to macrophage activation and promotes a procalcific environment. In addition, streptozotocin-induced diabetic Apoe-/-S100a9-/- mice and mice treated with S100a9 siRNA encapsulated in macrophage-targeted lipid nanoparticles showed decreased inflammation and microcalcification in atherosclerotic plaques, as gauged by molecular imaging and comprehensive histological analysis. In human carotid plaques, comparative proteomics in patients with diabetes mellitus and histological analysis showed that the S100A9-RAGE axis associates with osteogenic activity and the formation of microcalcification. Under hyperglycemic conditions, macrophages release calcific extracellular vesicles through mechanisms involving the S100A9-RAGE axis, thus contributing to the formation of microcalcification within atherosclerotic plaques.

Endothelial-to-Mesenchymal Transition, Vascular Inflammation, and Atherosclerosis.

Atherosclerosis is a chronic progressive disease characterized by vascular inflammation and growth of atherosclerotic plaque that eventually lead to compromise of blood flow. The disease has proven to be remarkably resistant to multiple attempts at meaningful reversal including recent strategies targeting selective inflammatory mediators. Endothelial-to-mesenchymal transition (EndMT) has emerged as a key driver of both vascular inflammation and plaque growth. A deeper understanding of EndMT provides new insights into the underlying biology of atherosclerosis, suggests likely molecular mechanism of atherosclerotic resistance, and identifies potential new therapeutic targets.

Effects of dipeptidyl peptidase 4 inhibition on inflammation in atherosclerosis: A 18F-fluorodeoxyglucose study of a mouse model of atherosclerosis and type 2 diabetes

Background and aimsDipeptidyl peptidase 4 (DPP-4) inhibitors have anti-inflammatory and atheroprotective effects. We evaluated the effects of the DPP-4 inhibitor linagliptin on atherosclerotic plaque and hepatic inflammation using histology and 2-deoxy-2-[18F]-fluoro-d-glucose (18F-FDG), a positron emission tomography tracer of inflammation, in a mouse model of hypercholesterolemia and type 2 diabetes. MethodsIgf2/Ldlr−/−Apob100/100 mice were fed a high-fat diet (HFD) for 8 weeks and then randomly allocated to receive HFD (n = 14), or HFD with added linagliptin (n = 15) for additional 12 weeks. Five mice fed a chow diet were studied as an additional control. At the end of the study, glucose tolerance, aortic and liver uptake of 18F-FDG, and histology were studied. ResultsMice in linagliptin and HFD groups had similar fasting glucose concentrations, but linagliptin improved glucose tolerance. Aortas of linagliptin and HFD groups showed advanced atherosclerotic plaques with no difference in the mean intima-to-media ratio or number of macrophages in the plaques. Autoradiography showed similar 18F-FDG uptake by atherosclerotic plaques in linagliptin and HFD groups (plaque-to-wall ratio: 1.7 ± 0.25 vs. 1.6 ± 0.21; p = 0.24). In the liver, linagliptin reduced the histologic inflammation score but had no effect on 18F-FDG uptake. Compared with chow diet, uptake of 18F-FDG was similar in the aorta, but higher in the liver after HFD. ConclusionsLinagliptin therapy improved glucose tolerance and reduced hepatic inflammation but had no effect on plaque burden or atherosclerotic inflammation, as determined by histology and 18F-FDG uptake, in atherosclerotic mice with type 2 diabetes.

T-Cell Molecular Modulation Responses in Atherosclerosis Anergy.

Atherosclerosis continues to be a major cause of death in patients with cardiovascular diseases. The cooperative role of immunity has been recently considered in atherosclerotic plaque inflammation, especially adaptive immune response by T cells. In this review, we examine the possible role of T cells in atherosclerosis-mediated inflammation and conceivable therapeutic strategies that can ameliorate complications of atherosclerosis. The cytokines secreted by T-lymphocyte subsets, different pathophysiological profiles of microRNAs (miRs), and the growth factor/receptor axis have diverse effects on the inflammatory cycle of atherosclerosis. Manipulation of miRNA expression and prominent growth factor receptors involved in inflammatory cytokine secretion in atherosclerosis can be considered diagnostic biomarkers in the induction of anergy and blockade of atherosclerotic development. This manuscript reviews immunomodulation of T cells responses in atherosclerosis anergy.