Factor Xa inhibitor rivaroxaban suppresses experimental abdominal aortic aneurysm progression via attenuating aortic inflammation.

OBJECTIVE: Rivaroxaban is a specific factor Xa (FXa) inhibitor for venous thromboembolism treatment. Recently, increasing evidence have reported the beneficial effects of rivaroxaban on treating cardiovascular disorders such as coronary and peripheral artery disease. However, its potential influence on abdominal aortic aneurysm (AAA) remains unclear. This study aims to investigate whether rivaroxaban treatment could attenuate experimental AAA progression and its related mechanisms. APPROACHES AND RESULTS: In human aneurysmal aorta, FXa protein expression was significantly upregulated. Further investigations identified a positive correlation among plasma FXa level, AAA severity (the maximal aortic diameter), and intra-aneurysmal thrombus percentage. In Ang II (angiotensin II)-infused ApoE-/- mice, the administration of high dose rivaroxaban (15 mg/kg/d) for 14 days significantly reduced the maximal aortic diameter, while low dose rivaroxaban (5 mg/kg/d) did not display such a protective role. Although rivaroxaban treatments reduced the incidence of AAA and thrombus formation, these differences did not reach statistical significance. Immunohistochemistry revealed a pronounced aortic remodeling including increased collagen content and enhanced elastin degradation in Ang II-induced AAAs, which was inhibited by high dose rivaroxaban treatment. Further analysis demonstrated that rivaroxaban exerted its protective effects by decreasing leukocyte infiltration, inflammatory cytokines expression, and matrix metalloproteinases (MMPs) expression in the aortic wall. The inhibitory effect of rivaroxaban on aneurysm development was also observed in calcium chloride-induced AAA model. Mechanistically, in human aortic endothelial cells, FXa stimulation increased the expression of inflammatory cytokines (interleukin (IL)-1ß, IL-6, IL-8, monocyte chemoattractant protein-1) and adhesive molecules, which were all reversed by the cotreatment of rivaroxaban. Subsequent monocyte-endothelial cell interaction was enhanced after FXa stimulation and was alleviated by rivaroxaban cotreatment. In addition, FXa induced a significantly heightened expression of MMP2 in human aortic endothelial cells, which was ameliorated by rivaroxaban coadministration. CONCLUSIONS: Rivaroxaban attenuated both angiotensin II- and calcium chloride-induced abdominal aortic aneurysm (AAA) progressions, through inhibiting aortic remodeling and inflammation. Rivaroxaban could be a promising therapeutic agent in attenuating AAA development by counteracting FXa-induced aortic wall inflammation.

MicroRNA-223 triggers inflammation in porcine aorta by activating NLRP3 inflammasome under selenium deficiency.

Selenium (Se) is an essential trace element in organism. Se deficiency can cause many diseases, including vascular disease. Studies have shown that inflammation is the main inducement of vascular disease, microRNA (miRNA) can influence inflammation in various ways, and Se deficiency can affect miRNAs expression. To study the mechanism of aorta damage caused by Se deficiency, we constructed a Se deficiency porcine aorta model and found that Se deficiency can significantly inhibit miR-223, which downregulates the expression of nucleotide-binding oligomerization domain-like receptor family 3 (NLRP3). Subsequently, we found that in Se deficiency group, NLRP3, and its downstream (caspase-1, apoptosis-related spot-like protein [ASC], IL-18, IL-1ß) expression was significantly increased. In vitro, we cultured pig iliac endothelium cell lines, and constructed miR-223 knockdown and overexpression models. NLRP3 messenger RNA and protein levels were significant increased in the knockdown group, and decreased in the overexpression group. The results of this study show that Se deficiency in porcine arteries can induce inflammation through miR-223/NLRP3.

Inhibition of interleukin-6 signaling attenuates aortitis, left ventricular hypertrophy and arthritis in interleukin-1 receptor antagonist deficient mice.

The aim of the present study was to examine whether inhibition of Interleukin (IL)-6 signaling by MR16-1, an IL-6 receptor antibody, attenuates aortitis, cardiac hypertrophy, and arthritis in IL-1 receptor antagonist deficient (IL-1RA KO) mice. Four weeks old mice were intraperitoneally administered with either MR16-1 or non-immune IgG at dosages that were adjusted over time for 5 weeks. These mice were stratified into four groups: MR16-1 treatment groups, KO/MR low group (first 2.0 mg, following 0.5 mg/week, n=14) and KO/MR high group (first 4.0 mg, following 2.0 mg/week, n=19) in IL-1RA KO mice, and IgG treatment groups, KO/IgG group (first 2.0 mg, following 1.0 mg/week, n=22) in IL-1RA KO mice, and wild/IgG group (first 2.0 mg, following 1.0 mg/week, n=17) in wild mice. Aortitis, cardiac hypertrophy and arthropathy were histologically analyzed. Sixty-eight percent of the KO/IgG group developed aortitis (53% developed severe aortitis). In contrast, only 21% of the KO/MR high group developed mild aortitis, without severe aortitis (P<0.01, vs KO/IgG group). Infiltration of inflammatory cells, such as neutrophils, T cells, and macrophages, was frequently observed around aortic sinus of the KO/IgG group. Left ventricle and cardiomyocyte hypertrophy were observed in IL-1RA KO mice. Administration of high dosage of MR16-1 significantly suppressed cardiomyocyte hypertrophy. MR16-1 attenuated the incidence and severity of arthritis in IL-1RA KO mice in a dose-dependent manner. In conclusion, blockade of IL-6 signaling may exert a beneficial effect to attenuate severe aortitis, left ventricle hypertrophy, and arthritis.

The Protective Effect of Crataegus aronia Against High-Fat Diet-Induced Vascular Inflammation in Rats Entails Inhibition of the NLRP-3 Inflammasome Pathway.

This study investigated whether the whole-plant aqueous extract of Crataegus aronia (C. aronia) could protect against or alleviate high-fat diet (HFD)-induced aortic vascular inflammation in rats by inhibiting the NLRP-3 inflammasome pathway and examined some mechanisms of action with respect to its antioxidant and hypolipidemic effects. Adult male Wistar rats were divided into five groups (n = 6/each): standard diet (10% fat) fed to control rats, control + C. aronia (200 mg/kg), HFD (40% fat), HFD + C. aronia, and HFD post-treated with C. aronia. The HFD was fed for 8 weeks and C. aronia was administered orally for 4 weeks. In addition, isolated macrophages from control rats were pre-incubated with two doses of C. aronia (25 and 50 µg/mL) with or without lipopolysaccharide (LPS) stimulation. Only in HFD-fed rats, co- and post-C. aronia therapy lowered circulatory levels of LDL-C and ox-LDL-c and aortic protein levels of LOX-1 and CD36. C. aronia also inhibited the nuclear accumulation of NF-κB and lowered protein levels of NLRP-3, caspase-1, and mature IL-1ß. In vitro, in the absence of ox-LDL-c, C. aronia led to reduced nuclear levels of NF-κB, ROS generation, and protein NLRP-3 levels, in both LPS-stimulated and unstimulated macrophages, in a dose-dependent manner. However, protein levels of LOX-1 were not affected by C. aronia in unstimulated cells. In conclusion, C. aronia inhibits the NLRP-3 inflammasome pathway, induced by HFD feeding in the aorta of rats, mainly by its hypolipidemic effect and in vitro, in LPS-stimulated macrophages, by its antioxidant effect.

Flaxseed oil rich in omega-3 protects aorta against inflammation and endoplasmic reticulum stress partially mediated by GPR120 receptor in obese, diabetic and dyslipidemic mice models.

The "first hit" to atherogenesis is driven by toll-like receptor 4, endoplasmic reticulum stress and ultimately metabolic dysfunction. In this study, we hypothesized that a flaxseed oil-enriched diet (FS) abolishes these inflammatory signaling pathway and restore metabolic homeostasis by activating the fatty acid receptor GPR120 in aorta of obese mice. Glucose homeostasis was assessed by GTT and ITT; lipidomics was performed using a Hybrid Ion Trap-Orbitrap Mass Spectrometer; serum lipids were measured using colorimetric assays; GPR120 and infiltrating macrophages were analyzed by immunofluorescence; protein immunoprecipitation and gene expression were evaluated by Western blot and RT-PCR, respectively. There were no differences in body weight and food intake between the groups from both strains (Swiss and LDLr-KO mice). GTT and cholesterol levels were improved by FS in both mice models. Lipidomics showed an increase in ω3 (C18:3) content, meanwhile stearic acid (C18:0) was not detected in endothelial tissue in response to FS. Moreover, FS markedly decreased pro-inflammatory (IL-1ß, TNF-α, pIκBα, pIKKß) and unfolded protein response markers (ATF6 and GRP78) in aorta. In Swiss mice, GPR120 was partially involved in the ω3-mediated anti-inflammatory actions, disrupting TLR4 pathway, but not in LDLr-KO mice. Partial replacement of dietary saturated by unsaturated ω3 fatty acids contributes to inhibition of cardiovascular risk markers, pro-inflammatory cytokines and ER stress sensors and effectors in the aorta. However, downregulation of inflammation is not mediated by arterial GPR120 activation.

Inhibitory effects of Akebia quinata ethanol extract on TNF-α-mediated vascular inflammation in human aortic smooth muscle cells.

Atherosclerosis is a chronic inflammatory disease of the arterial wall. The expression of adhesion molecules in aortic smooth muscle cells facilitates the accumulation of transmigrated leukocytes within the atherosclerotic vascular wall. The stem of Akebia quinata (A. quinata) has previously been used as a crude drug for treating urinary disorders and inflammatory disease in Korea, China and Japan. In the present study, we investigated the effect of an A. quinata ethanol extract (AQEE) on the expression of adhesion molecules and cyclooxygenase-2 (COX­2) in tumor necrosis factor α (TNF-α)-induced human aortic smooth muscle cells (HASMCs). The results of the present study demonstrated that AQEE attenuated intercellular adhesion molecule 1, E­selectin and COX­2 expression in TNF­α-stimulated HASMCs and inhibited THP-1 cell adhesion to activated HASMCs. Furthermore, AQEE suppressed the TNF­α induced phosphorylation of p38 mitogen-activated protein kinase (MAPK) and reduced nuclear factor κB (NF-κB; p65) nuclear translocation. The present study demonstrated that AQEE possesses anti­inflammatory properties and regulates TNF-α-induced expression of adhesion molecules by inhibition of the p38 MAPK/NF-κB signaling pathway.

Rapid-clearance iron nanoparticles for inflammation imaging of atherosclerotic plaque: initial experience in animal model.

PURPOSE: To evaluate the use of a recently developed fast-clearing ultrasmall superparamagnetic iron oxide (USPIO) for detection of vascular inflammation in atherosclerotic plaque. MATERIALS AND METHODS: The study protocol was approved by the animal experimentation ethics committee. A recently introduced USPIO, P904, and a reference-standard USPIO, ferumoxtran-10, were tested in a rabbit model of induced aortic atherosclerosis. In vivo magnetic resonance (MR) angiography and T2*-weighted plaque MR imaging were performed at baseline and after administration of P904 and ferumoxtran-10 (administered dose for both, 1000 micromol of iron per kilogram of body weight) in 26 hyperlipidemic New Zealand white rabbits. The variation in vessel wall area over time was evaluated with nonparametric testing. Ex vivo MR imaging findings were compared with iron content at linear regression analysis. RESULTS: With in vivo MR imaging, plaque analysis was possible as early as 24 hours after P904 injection. The authors observed a 27.75% increase in vessel wall area due to susceptibility artifacts on day 2 (P = .04) and a 38.81% increase on day 3 (P = .04) after P904 administration compared with a 44.5% increase in vessel wall area on day 7 (P = .04) and a 34.8% increase on day 10 (P = .22) after ferumoxtran-10 administration. These susceptibility artifacts were correlated with intraplaque iron uptake in the corresponding histologic slices. The number of pixels with signal loss on the ex vivo MR images was linearly correlated with the logarithm of the iron concentration (P = .0001; R(2) = 0.93). CONCLUSION: Plaque inflammation in rabbits can be detected earlier with P904 than with ferumoxtran-10 owing to the faster blood pharmacokinetics and the early uptake of P904 in the reticuloendothelial system. SUPPLEMENTAL MATERIAL: http://radiology.rsnajnls.org/cgi/content/full/252/2/401/DC1.