Shuntaro Matsuda

Disturbed blood flow induces erosive injury to smooth muscle cell‐rich neointima and promotes thrombus formation in rabbit femoral arteries

Summary.  Background: Plaque erosion is a cause of atherothrombosis that preferentially occurs on smooth muscle cell (SMC)‐ and proteoglycan‐rich rather than lipid‐rich plaques. However, its underlying mechanisms remain unknown. Objective: To determine whether disturbed blood flow induces erosive injury and thrombus formation on SMC‐rich neointima. Methods: Three weeks after balloon injury, SMC‐rich neointima with increased tissue factor (TF) activity developed in rabbit femoral arteries that were narrowed with a vascular occluder to disturb blood flow after stenosis. Neointimal injury and thrombus formation were assessed at 15, 30, and 180 min after the vascular narrowing. Results: Endothelial detachment, platelet adhesion and neointimal cell apoptosis became evident at the post‐stenotic regions of all femoral arteries (n = 5) within 15 min of narrowing. Mural thrombi composed of platelet and fibrin developed after 30 min, and then occlusive thrombi were generated in three out of five vessels after 180 min. The identical vascular narrowing of normal femoral arteries also induced endothelial detachment with small platelet thrombi at post‐stenotic regions, but fibrin and occlusive thrombi did not develop. Computational simulation analysis indicated that oscillatory shear stress contributes to the development of erosive damage to the neointima. Conclusions: These results suggest that disturbed post‐stenotic blood flow can induce erosive injury in SMC‐rich plaques and promote thrombus formation that results in vascular events.

Plasma Pentraxin 3, but not High-sensitivity C-reactive Protein, is a Useful Inflammatory Biomarker for Predicting Cognitive Impairment in Elderly Hypertensive Patients

BACKGROUND Due to the increasing longevity of human populations worldwide, there is need of a useful biomarker for the early detection of cognitive impairment in elderly persons. Both high blood pressure (BP) and inflammatory processes have been reported to be involved in cognitive impairment via cerebrovascular atherosclerosis or neuronal cell damage. METHODS In this cross-sectional study of 210 ambulatory elderly hypertensive patients without clinically evident dementia (mean age: 74 years; 44% men), we measured 24-hour BP, circulatory pentraxin 3 (PTX3) and high-sensitivity C-reactive protein (hs-CRP) levels, and cognitive function (Mini-Mental State Examination [MMSE]). RESULTS A high plasma PTX3 level was observed in lean subjects, especially in those whose current body weight was lower than that measured 5 years earlier, whereas a high hs-CRP level was associated with obesity (all p < .05). Both PTX3 and hs-CRP levels were significantly associated with the MMSE score (r = -.248, p<0.001 and r = -.153, p<0.05, respectively); however, in multiple regression analysis, the PTX3 level, but not the hs-CRP level, was inversely associated with the MMSE score independently of patient demographics, glucose and lipid metabolic parameters, 24-hour systolic BP (SBP) level, and the atherosclerotic burden (all p < .05). Moreover, there was a significant interaction between the PTX3 and 24-hour SBP levels in the determinants of MMSE score (p < .05). CONCLUSIONS A high plasma PTX3 level in elderly hypertensive patients, particularly in those with a high 24-hour BP level, could be a significant predictor of cognitive impairment. A high PTX3 level may be a marker of frailty in elderly hypertensive patients.

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.

Inhibition of factor XI reduces thrombus formation in rabbit jugular vein under endothelial denudation and/or blood stasis

INTRODUCTION In addition to acquired and inherited risk factors, the growth of venous thrombus under static conditions and endothelial injury play important roles in the development of deep venous thrombosis (DVT), for which risk factors include increased plasma levels of coagulation factor XI (FXI). The aim of this study is to understand the role of FXI in venous thrombus formation under conditions of endothelial denudation and/or blood stasis. MATERIALS AND METHODS The contribution of FXI to venous thrombus formation was investigated in a rabbit model and a flow chamber system. Thrombi were induced in the rabbit jugular veins by (1) endothelial denudation, (2) vessel ligation (blood stasis) or (3) by combined endothelial denudation and vessel ligation. Blood samples were perfused on immobilized type III collagen at a wall shear rate of 70/s and then the surface area covered by platelets and fibrin was morphometrically evaluated. Prothrombin fragment 1+2 (F1+2) generation was also measured before and after perfusion. RESULTS All thrombi induced in rabbit jugular veins were composed of platelets, fibrin and erythrocytes. Anti-FXI antibody significantly reduced ex vivo plasma thrombin generation initiated by ellagic acid but not by tissue factor, and in vivo thrombus formation under endothelial denudation and/or vessel ligation. The antibody significantly reduced surface areas covered by platelets and fibrin, as well as F1+2 generation at a wall shear rate of 70/s in flow chambers. CONCLUSION These results suggest that FXI contributes to venous thrombus growth under conditions of endothelial denudation and/or blood stasis, and that thrombin generation by FXI interaction promotes further platelet aggregation and fibrin formation at low shear rates.

Circulating Des-acyl Ghrelin Improves Cardiovascular Risk Prediction in Older Hypertensive Patients

BACKGROUND We aimed to assess the predictive value of circulating levels of des-acyl ghrelin, an abundant form of ghrelin in humans, for the risk of cardiovascular disease (CVD) in older hypertensive patients. We simultaneously evaluated other biomarkers, such as high-molecular-weight (HMW) adiponectin, high-sensitivity C-reactive protein (hs-CRP), and plasminogen activator inhibitor 1 (PAI-1), for their usefulness in risk prediction. METHODS We enrolled 590 older hypertensive patients (mean age = 72.9 years; 41.0% men). The incidences of CVD, including coronary artery disease, stroke, congestive heart failure, and sudden death, were prospectively ascertained. RESULTS During an average duration of 2.8 (SD = 0.7) years (1,653 person-years), there were 42 CVD events. Patients with CVD events had lower levels of des-acyl ghrelin at baseline than those without CVD events (median = 78.2 vs. 114.7 fmol/ml; P < 0.001). No difference was found among other biomarkers between the patients with CVD events and those without such events. The Cox proportional hazards model adjusted by covariables revealed that the hazard ratio for CVD events in patients with a 1-SD decrease of log des-acyl ghrelin was 1.8 (95% confidence interval = 1.3-2.4). Incorporation of des-acyl ghrelin in the risk model (including age, current smoking, 24-hour systolic blood pressure, preexisting CVD, and carotid intima-media thickness) improved the C statistics (from 0.683 to 0.721; P = 0.22) and resulted in a net reclassification improvement of 20.5% (P = 0.02). In contrast, HMW adiponectin, hs-CRP, and PAI-1 provided no improvement in risk prediction. CONCLUSIONS Des-acyl ghrelin improved the prediction of CVD events in older hypertensive patients.

Regional differences in hypertensive cardiovascular remodeling between fishing and farming communities in Japan.

BACKGROUND Effects of dietary n-3 polyunsaturated fatty acids (n-3 PUFA) intake on the cardiovascular system have been reported, and thus we hypothesized that the prevalence of hypertensive cardiovascular remodeling would be lower in a fishing than a farming community. METHODS We recruited 263 essential hypertensives from a fishing and 333 from a farming village; all subjects were ≥40 years (mean 73 years; 42% men). They were cross-sectionally examined for serum eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), asymmetric dimethylarginine (ADMA) levels, left ventricular mass index (LVMI), and common-carotid artery (CCA) and internal-carotid artery (ICA) intima-media thickness (IMT). RESULTS Compared to the patients in the farming village, those in the fishing village had higher serum EPA and DHA levels (63.3 vs.70.9 µg/ml, 137.2 vs.157.8 µg/ml) and lower ADMA levels (0.49 vs.0.47 nmol/ml; all P < 0.05). LVMI and both CCA-IMT and ICA-IMT levels were lower in the fishing than the farming village (113.2 vs.121.6 g/m(2), 0.88 vs.0.94 mm, 1.10 vs.1.17 mm: all P < 0.01) even after adjustment for age, sex, body mass index (BMI), duration of hypertensive medication, number of antihypertensive medications, and 24-h systolic blood pressure (SBP) level. The differences in LVMI and IMT levels between these communities also remained unchanged (all P < 0.01) after additional adjustment for the regional differences in EPA, DHA, and ADMA levels. A multivariable linear regression analysis showed that the difference in place of residence was independently associated with LVMI as well as with both CCA-IMT and ICA-IMT levels (all P < 0.01). CONCLUSION The prevalence of cardiovascular remodeling was significantly lower in patients in the fishing community than in those in the farming community. Further investigations are required to explain the mechanisms underlying this association.

Human C-reactive protein enhances thrombus formation after neointimal balloon injury in transgenic rabbits

Summary.  Background: High plasma levels of C‐reactive protein (CRP) constitute a powerful predictive marker of cardiovascular events. Several lines of evidence suggest that CRP has prothrombogenic effects. However, whether CRP directly participates in the pathogenesis of thrombosis in vivo has not been fully clarified. Objective: To test whether human CRP (hCRP) affects arterial thrombus formation after balloon injury of smooth muscle cell (SMC)‐rich or macrophage‐rich neointima. Methods: We compared the susceptibility of transgenic (Tg) rabbits expressing hCRP (46.21 ± 13.85 mg L−1, n = 22) and non‐Tg rabbits to arterial thrombus formation after balloon injury of SMC‐rich or macrophage‐rich neointima. Results: Thrombus size on SMC‐rich or macrophage‐rich neointima was significantly increased, and was accompanied by an increase in fibrin content in hCRP‐Tg rabbits, as compared with non‐Tg rabbits. Thrombus size did not significantly differ between SMC‐rich and macrophage‐rich neointima in hCRP‐Tg rabbits. Tissue factor (TF) mRNA expression and activity in these neointimal lesions were significantly increased in hCRP‐Tg rabbits as compared with non‐Tg rabbits. The degree of CRP deposition correlated with the elevated TF expression and thrombus size on injured neointima. In addition, hCRP isolated from hCRP‐Tg rabbit plasma induced TF mRNA expression and activity in rabbit cultured vascular SMCs. Conclusions: These results suggest that elevated plasma hCRP levels promote thrombus formation on injured SMC‐rich neointima by enhancing TF expression, but have no additive effects in macrophage‐rich neointima.

Human Coronary Thrombus Formation Is Associated With Degree of Plaque Disruption and Expression of Tissue Factor and Hexokinase II

BACKGROUND Atherosclerotic plaque thrombogenicity is a critical factor that affects thrombus formation and the onset of acute myocardial infarction (AMI). The aim of this study was to identify the vascular factors involved in thrombus formation and AMI onset. METHODSANDRESULTS Culprit lesions in 40 coronary arteries with thrombi at autopsy after lethal AMI and non-cardiac death (asymptomatic plaque disruption) were analyzed on histology. Thrombus size, ratio of thrombus to lumen area, length of plaque disruption, and immunopositive areas for tissue factor (TF) and hexokinase (HK)-II were significantly larger in coronary arteries with AMI than with asymptomatic plaque disruption. The size of coronary thrombus positively correlated with the length of plaque disruption (r=0.80) and with immunopositive areas for TF (r=0.38) and HK-II (r=0.40). Because both M1 and M2 macrophages express TF and HK-II in symptomatic plaques, we assessed TF and HK-II expression in M1- and M2-polarized macrophages. The expression of TF was increased and that of HK-II was decreased in M2-, compared with M1-polarized THP-1 macrophages. Inhibiting glycolysis enhanced TF expression in the macrophages partly via hypoxia inducible factor-1α. CONCLUSIONS The degree of plaque disruption and expression of TF and HK-II appear to be important vascular factors for AMI onset, and polarized macrophages make a distinct contribution to thrombogenicity and glucose metabolism.

Hemangioma of the Umbilical Cord with Pseudocyst

A case of umbilical cord hemangioma with a large cystic mass, diagnosed by ultrasound at 18 weeks of gestation, is reported. A normal female infant was born at 39 weeks of gestation. The umbilical cord was 32 cm long with a cystic mass (10 × 10 × 8 cm). Histopathologic examination of the umbilical cord revealed a hemangioma with myxomatous degeneration, presenting as a large cyst with thinning of the umbilical venous wall. A total of 33 umbilical cord hemangioma cases have been reported in detail, and only seven cases had a pseudocystic degeneration. The associated pathologic findings of umbilical cord hemangioma are reviewed.

Elevated plasma factor VIII enhances venous thrombus formation in rabbits: Contribution of factor XI, von Willebrand factor and tissue factor

Elevated plasma levels of factor VIII (FVIII) are associated with increased risk of deep venous thrombosis. The aim of this study is to elucidate how elevated FVIII levels affect venous thrombus formation and propagation in vivo. We examined rabbit plasma FVIII activity, plasma thrombin generation, whole blood coagulation, platelet aggregation and venous wall thrombogenicity before and one hour after an intravenous infusion of recombinant human FVIII (rFVIII). Venous thrombus induced by the endothelial denudation of rabbit jugular veins was histologically assessed. Thrombus propagation was evaluated as indocyanine green fluorescence intensity. Argatroban, a thrombin inhibitor, and neutralised antibodies for tissue factor (TF), factor XI (FXI), and von Willebrand factor (VWF) were infused before or after thrombus induction to investigate their effects on venous thrombus formation or propagation. Recombinant FVIII (100 IU/kg) increased rabbit plasma FVIII activity two-fold and significantly enhanced whole blood coagulation and total plasma thrombin generation, but did not affect initial thrombin generation time, platelet aggregation and venous wall thrombogenicity. The rFVIII infusion also increased the size of venous thrombus 1 hour after thrombus induction. Argatroban and the antibodies for TF, FXI or VWF inhibited such enhanced thrombus formation and all except TF suppressed thrombus propagation. In conclusion, elevated plasma FVIII levels enhance venous thrombus formation and propagation. Excess thrombin generation by FXI and VWF-mediated FVIII recruitment appear to contribute to the growth of FVIII-driven venous thrombus.