Elevated plasma levels of factor VIII enhance arterial thrombus formation on erosive smooth muscle cell-rich neointima but not normal intima in rabbits.

BACKGROUND: Plaque erosion, a type of coronary atherothrombosis, involves superficial injury to smooth muscle cell (SMC)-rich plaques. Elevated levels of coagulation factor VIII (FVIII) correlate with an increased ischemic heart disease risk. FVIII may contribute to thrombus formation on eroded plaques. AIMS: We aimed to elucidate the role of elevated FVIII in arterial thrombus formation within SMC-rich neointima in rabbits. METHODS AND RESULTS: We assessed the effect of recombinant human FVIII (rFVIII) on blood coagulation in vitro and platelet aggregation ex vivo. An SMC-rich neointima was induced through balloon injury to the unilateral femoral artery. Three weeks after the first balloon injury, superficial erosive injury and thrombus formation were initiated with a second balloon injury of the bilateral femoral arteries 45 min after the administration of rFVIII (100 IU/kg) or saline. The thrombus area and contents were histologically measured 15 min after the second balloon injury. rFVIII administration reduced the activated partial thromboplastin time and augmented botrocetin-induced, but not collagen- or adenosine 5'-diphosphate-induced, platelet aggregation. While rFVIII did not influence platelet-thrombus formation in normal intima, it increased thrombus formation on SMC-rich neointima post-superficial erosive injury. Enhanced immunopositivity for glycoprotein IIb/IIIa and fibrin was observed in rFVIII-administered SMC-rich neointima. Neutrophil count in the arterial thrombus on the SMC-rich neointima correlated positively with thrombus size in the control group, unlike the rFVIII group. CONCLUSIONS: Increased FVIII contributes to thrombus propagation within erosive SMC-rich neointima, highlighting FVIII's potential role in plaque erosion-related atherothrombosis.

Glucosyl Hesperidin Has an Anti-diabetic Effect in High-Fat Diet-Induced Obese Mice.

Glucosyl hesperidin (GH) is a water-soluble derivative of hesperidin, a citrus flavonoid. GH has various pharmacological effects, such as hypolipidemic and hypouricemic effects, and may therefore be a useful supplement or drug. In the present study, we evaluated the effects of long- and short-term intake of GH on hyperglycemia and macrophage infiltration into the adipose tissue of high-fat diet (HFD)-fed mice. Long-term (11-week) consumption of GH tended to reduce body weight and the fasting blood glucose concentration of the HFD-fed mice, and ameliorated glucose intolerance and insulin resistance, according to glucose and insulin tolerance tests. Additionally, although GH did not affect fat pad weight, it reduced HFD-induced macrophage infiltration into adipose tissue. Short-term (2-week) consumption of GH did not affect the HFD-induced increases in body weight or fasting blood glucose, and it did not ameliorate glucose intolerance or insulin resistance. However, short-term intake did reduce the HFD-induced macrophage infiltration and monocyte chemotactic protein 1 (MCP-1) expression in adipose tissue. Furthermore, hesperetin, which is an aglycone of GH, inhibited MCP-1 expression in 3T3-L1 adipocytes, 3T3-L1 adipocytes co-cultured with RAW264 macrophages, and tumor necrosis factor-α-treated 3T3-L1 adipocytes. The present findings suggest that daily consumption of GH may have preventive and/or therapeutic effects on obesity-related diseases, such as diabetes mellitus.

Naringenin suppresses neutrophil infiltration into adipose tissue in high-fat diet-induced obese mice.

Recruitment of immune cells to adipose tissue is altered dramatically in obesity, which results in chronic inflammation of the adipose tissue that leads to metabolic disorders, such as insulin resistance and type 2 diabetes mellitus. The regulation of immune cell infiltration into adipose tissue has prophylactic and therapeutic implications for obesity-related diseases. We previously showed that naringenin, a citrus flavonoid, suppressed macrophage infiltration into adipose tissue by inhibiting monocyte chemoattractant protein-1 (MCP-1) expression in the progression phase to high-fat diet (HFD)-induced obesity. In the current study, we evaluated the effects of naringenin on neutrophil infiltration into adipose tissue, because neutrophils also infiltrate into adipose tissue in the progression phase to obesity. Naringenin suppressed neutrophil infiltration into adipose tissue induced by the short-term (2 weeks) feeding of a HFD to mice. Naringenin tended to inhibit the HFD-induced expression of several chemokines, including MCP-1 and MCP-3, in adipose tissue. Naringenin also inhibited MCP-3 expression in 3T3-L1 adipocytes and a co-culture of 3T3-L1 adipocytes and RAW264 macrophages. However, naringenin did not affect the expression of macrophage inflammatory protein-2 (MIP-2), an important chemokine for neutrophil migration and activation, in macrophages or in a co-culture of adipocytes and macrophages. Our results suggest that naringenin suppresses neutrophil infiltration into adipose tissue via the regulation of MCP-3 expression and macrophage infiltration.

Higher lactate and purine metabolite levels in erythrocyte-rich fresh venous thrombus: Potential markers for early deep vein thrombosis.

BACKGROUND: Thrombolytic therapy is effective in fresh deep vein thrombosis (DVT) although the benefit may fall below the risk of bleeding in non-fresh thrombosis. Markers reflecting fresh DVT have not been established. The present study aims to identify metabolites reflecting fresh venous thrombus and their role in thrombus formation. METHODS: Metabolites of rabbit venous blood and jugular venous thrombus 4 h after thrombus induction were analysed using electrophoresis-time of flight mass spectrometry. The effects of the altered metabolites on blood coagulation and platelet aggregation were assessed by using rotation thromboelastometry and platelet aggregometer. Cellular contents and glucose transporter (Glut)-1 expression in aspirated human DVT samples were pathologically analysed. RESULTS: Metabolome analysis identified 226 metabolites (133 cationic and 93 anionic metabolites). Largely altered 18 metabolites (thrombus/blood ratio: >5 or <0.5) included glycolytic metabolites, redox-related metabolites, purine nucleotides and tryptophan metabolites. Among the metabolites with >5-fold increase, lactic acid was most abundant and guanine modestly enhanced whole blood clotting with thromboelastometry. Lactic acid and adenosine monophosphate inhibited collagen-induced platelet aggregation. Human DVTs were rich in erythrocytes expressing Glut-1. The erythrocyte content and Glut-1 expression were negatively correlated with the time after onset of DVT. CONCLUSIONS: Glycolysis-, purine-, and redox-related metabolites may reflect fresh erythrocyte-rich venous thrombus, and altered metabolites may affect venous thrombus formation. An increased level of lactate may reflect active glycolysis of thrombus cellular components, predominantly erythrocytes.

Perinatal exposure to tetrabromobisphenol A (TBBPA), a brominated flame retardant, exacerbated the pneumonia in respiratory syncytial virus (RSV)-infected offspring mice.

To investigate the effects of perinatal exposure to tetrabromobisphenol A (TBBPA), a brominated flame retardant, on the immune system, a respiratory syncytial virus (RSV) infection mouse model was utilized. Female mice were exposed to TBBPA mixed with the diet from 10 days after conception to weaning on postnatal day 21. Offspring mice were infected intranasally with A2 strain of RSV. Although no general toxicological sign was observed, the pulmonary viral titers of offspring mice exposed to 0.1% TBBPA were significantly increased compared with the control on day 5 post-infection. TBBPA did not affect RSV growth in vitro. Histopathological analysis confirmed that the exacerbation of interstitial pneumonia was due to TBBPA- exposure in the lung tissues in RSV-infected offspring. Moreover, gene expression of interleukin (IL)-24 was shown to be elevated typically in the lung tissues of TBBPA-treated offspring by a DNA microarray and was also confirmed by immunohistopathological analysis using an anti-IL-24 antibody. Thus, developmental exposure to TBBPA affected the immune response to RSV infection, resulting in the exacerbation of pneumonia. Thus, IL-24 should be a key molecule to understand the mechanism of action of TBBPA.

Altered glucose metabolism and hypoxic response in alloxan-induced diabetic atherosclerosis in rabbits.

Diabetes mellitus accelerates atherosclerosis that causes most cardiovascular events. Several metabolic pathways are considered to contribute to the development of atherosclerosis, but comprehensive metabolic alterations to atherosclerotic arterial cells remain unknown. The present study investigated metabolic changes and their relationship to vascular histopathological changes in the atherosclerotic arteries of rabbits with alloxan-induced diabetes. Diabetic atherosclerosis was induced in rabbit ilio-femoral arteries by injecting alloxan (100 mg/kg), injuring the arteries using a balloon, and feeding with a 0.5% cholesterol diet. We histologically assessed the atherosclerotic lesion development, cellular content, pimonidazole positive-hypoxic area, the nuclear localization of hypoxia-inducible factor-1α, and apoptosis. We evaluated comprehensive arterial metabolism by performing metabolomic analyses using capillary electrophoresis-time of flight mass spectrometry. We evaluated glucose uptake and its relationship to vascular hypoxia using 18F-fluorodeoxyglucose and pimonidazole. Plaque burden, macrophage content, and hypoxic areas were more prevalent in arteries with diabetic, than non-diabetic atherosclerosis. Metabolomic analyses highlighted 12 metabolites that were significantly altered between diabetic and non-diabetic atherosclerosis. A half of them were associated with glycolysis metabolites, and their levels were decreased in diabetic atherosclerosis. The uptake of glucose evaluated as 18F-fluorodeoxyglucose in atherosclerotic lesions increased according to increased macrophage content or hypoxic areas in non-diabetic, but not diabetic rabbits. Despite profound hypoxic areas, the nuclear localization of hypoxia-inducible factor-1α decreased and the number of apoptotic cells increased in diabetic atherosclerotic lesions. Altered glycolysis metabolism and an impaired response to hypoxia in atherosclerotic lesions under conditions of insulin-dependent diabetes might be involved in the development of diabetic atherosclerosis.

Vascular wall hypoxia promotes arterial thrombus formation via augmentation of vascular thrombogenicity.

Atherosclerotic lesions represent a hypoxic milieu. However, the significance of this milieu in atherothrombosis has not been established. We aimed to assess the hypothesis that vascular wall hypoxia promotes arterial thrombus formation. We examined the relation between vascular wall hypoxia and arterial thrombus formation using a rabbit model in which arterial thrombosis was induced by 0.5 %-cholesterol diet and repeated balloon injury of femoral arteries. Vascular wall hypoxia was immunohistochemically detected by pimonidazole hydrochloride, a hypoxia marker. Rabbit neointima and THP-1 macrophages were cultured to analyse prothrombotic factor expression under hypoxic conditions (1 % O2). Prothrombotic factor expression and nuclear localisation of hypoxia-inducible factor (HIF)-1α and nuclear factor-kappa B (NF-κB) p65 were immunohistochemically assessed using human coronary atherectomy plaques. Hypoxic areas were localised in the macrophage-rich deep portion of rabbit neointima and positively correlated with the number of nuclei immunopositive for HIF-1α and NF-κB p65, and tissue factor (TF) expression. Immunopositive areas for glycoprotein IIb/IIIa and fibrin in thrombi were significantly correlated with hypoxic areas in arteries. TF and plasminogen activator inhibitor-1 (PAI-1) expression was increased in neointimal tissues and/or macrophages cultured under hypoxia, and both were suppressed by inhibitors of either HIF-1 or NF-κB. In human coronary plaques, the number of HIF-1α-immunopositive nuclei was positively correlated with that of NF-κB-immunopositive nuclei and TF-immunopositive and PAI-1-immunopositive area, and it was significantly higher in thrombotic plaques. Vascular wall hypoxia augments the thrombogenic potential of atherosclerotic plaque and thrombus formation on plaques via prothrombotic factor upregulation.

Naringenin suppresses macrophage infiltration into adipose tissue in an early phase of high-fat diet-induced obesity.

Obese adipose tissue is characterized by increased macrophage infiltration, which results in chronic inflammation in adipose tissue and leads to obesity-related diseases such as type 2 diabetes mellitus and atherosclerosis. The regulation of macrophage infiltration into adipose tissue is an important strategy for preventing and treating obesity-related diseases. In this study, we report that naringenin, a citrus flavonoid, suppressed macrophage infiltration into adipose tissue induced by short-term (14 days) feeding of a high-fat diet in mice; although naringenin did not show any differences in high-fat diet-induced changes of serum biochemical parameters in this short administration period. Naringenin suppressed monocyte chemoattractant protein-1 (MCP-1) in adipose tissue, and this effect was mediated in part through inhibition of c-Jun NH2-terminal kinase pathway. Naringenin also inhibited MCP-1 expression in adipocytes, macrophages, and a co-culture of adipocytes and macrophages. Our results suggest a mechanism by which daily consumption of naringenin may exhibit preventive effects on obesity-related diseases.

Increased metabolite levels of glycolysis and pentose phosphate pathway in rabbit atherosclerotic arteries and hypoxic macrophage.

AIMS: Inflammation and possibly hypoxia largely affect glucose utilization in atherosclerotic arteries, which could alter many metabolic systems. However, metabolic changes in atherosclerotic plaques remain unknown. The present study aims to identify changes in metabolic systems relative to glucose uptake and hypoxia in rabbit atherosclerotic arteries and cultured macrophages. METHODS: Macrophage-rich or smooth muscle cell (SMC)-rich neointima was created by balloon injury in the iliac-femoral arteries of rabbits fed with a 0.5% cholesterol diet or a conventional diet. THP-1 macrophages stimulated with lipopolysaccharides (LPS) and interferon-γ (INFγ) were cultured under normoxic and hypoxic conditions. We evaluated comprehensive arterial and macrophage metabolism by performing metabolomic analyses using capillary electrophoresis-time of flight mass spectrometry. We evaluated glucose uptake and its relationship to vascular hypoxia using (18)F-fluorodeoxyglucose ((18)F-FDG) and pimonidazole, a marker of hypoxia. RESULTS: The levels of many metabolites increased in the iliac-femoral arteries with macrophage-rich neointima, compared with those that were not injured and those with SMC-rich neointima (glycolysis, 4 of 9; pentose phosphate pathway, 4 of 6; tricarboxylic acid cycle, 4 of 6; nucleotides, 10 of 20). The uptake of (18)F-FDG in arterial walls measured by autoradiography positively correlated with macrophage- and pimonidazole-immunopositive areas (r = 0.76, and r = 0.59 respectively; n = 69 for both; p<0.0001). Pimonidazole immunoreactivity was closely localized with the nuclear translocation of hypoxia inducible factor-1α and hexokinase II expression in macrophage-rich neointima. The levels of glycolytic (8 of 8) and pentose phosphate pathway (4 of 6) metabolites increased in LPS and INFγ stimulated macrophages under hypoxic but not normoxic condition. Plasminogen activator inhibitor-1 protein levels in the supernatant were closely associated with metabolic pathways in the macrophages. CONCLUSION: Infiltrative macrophages in atherosclerotic arteries might affect metabolic systems, and hypoxia but not classical activation might augment glycolytic and pentose phosphate pathways in macrophages.

Thrombin generation by intimal tissue factor contributes to thrombus formation on macrophage-rich neointima but not normal intima of hyperlipidemic rabbits.

Arterial thrombosis occurs in atherosclerotic, but rarely in non-atherosclerotic arteries. The present study investigates how hyperlipidemic condition affects thrombus formation on macrophage-rich neointima or normal intima in rabbits. Rabbits were fed with a 0.5% cholesterol diet, and then the femoral artery on one side of each rabbit was injured with a balloon catheter. Three weeks later, bilateral femoral arteries were similarly injured with a balloon catheter to produce thrombi on neointima and normal intima. We compared the expression and activity of intimal tissue factor (TF) as well as thrombus size and composition between these femoral arteries. 0.5% cholesterol diet combined with a balloon injury induced macrophage-rich neointima in injured arteries. The whole blood coagulation activity or plasma thrombin generation activity did not differ after consuming the 0.5% cholesterol diet for 4 weeks, and an anti-TF antibody did not affect the measured parameters. TF activities were increased in the neointima/media compared with normal intima/media. Balloon injury induced large platelet-fibrin thrombi on macrophage-rich neointima, whereas small platelet thrombi were produced in normal arteries even under hyperlipidemic conditions. Recombinant human tissue factor pathway inhibitor (25microg/(kgmin)) and argatroban (100microg/(kgmin)), a specific thrombin inhibitor, significantly reduced thrombus formation on induced neointima, but not on normal intima. Thrombin generation mediated by TF in intima contributes to thrombus formation on macrophage-rich neointima, but not on normal intima. The TF content in disrupted atherosclerotic plaques might play a more important role than hyperlipidemia in the development of atherothrombosis.