Mitsunori Fujimura

Disruption of Nuclear Vitamin D Receptor Gene Causes Enhanced Thrombogenicity in Mice

Vitamin D metabolites influence the expression of various genes involved in calcium homeostasis, cell differentiation, and regulation of the immune system. Expression of these genes is mediated by the activation of the nuclear vitamin D receptor (VDR). Previous studies have shown that a hormonally active form of vitamin D, 1α,25-dihydroxyvitamin D3, exerts anticoagulant effects in cultured monocytic cells. To clarify whether activation of VDR plays any antithrombotic actions in vivo, hemostatic/thrombogenic systems were examined in normocalcemic VDR knock-out (KO) mice on a high calcium diet and compared with wild type and hypocalcemic VDRKO mice that were fed a regular diet. Platelet aggregation was enhanced significantly in normocalcemic VDRKO mice compared with wild type and hypocalcemic VDRKO mice. Aortic endothelial nitric-oxide (NO) synthase expression and urinary NOx excretions were reduced in hypocalcemic VDRKO mice, but not in normocalcemic VDRKO mice. Northern blot and RT-PCR analyses revealed that the gene expression of antithrombin in the liver as well as that of thrombomodulin in the aorta, liver and kidney was down-regulated in hypo- and normocalcemic VDRKO mice. Whereas tissue factor mRNA expression in the liver and kidney was up-regulated in VDRKO mice regardless of plasma calcium level. Furthermore, VDRKO mice manifested an exacerbated multi-organ thrombus formation after exogenous lipopolysaccharide injection regardless of the calcemic conditions. These results demonstrate that activation of nuclear VDR elicits antithrombotic effects in vivo, and suggest that the VDR system may play a physiological role in the maintenance of antithrombotic homeostasis.

Androgen Receptor Gene Knockout Male Mice Exhibit Impaired Cardiac Growth and Exacerbation of Angiotensin II-induced Cardiac Fibrosis

Androgen has anabolic effects on cardiac myocytes and has been shown to enhance left ventricular enlargement and function. However, the physiological and patho-physiological roles of androgen in cardiac growth and cardiac stress-induced remodeling remains unclear. We aimed to clarify whether the androgen-nuclear androgen receptor (AR) system contributes to the cardiac growth and angiotensin II (Ang II)-stimulated cardiac remodeling by using systemic AR-null male mice. AR knock-out (ARKO) male mice, at 25 weeks of age, and age-matched wild-type (WT) male mice were treated with or without Ang II stimulation (2.0 mg/kg/day) for 2 weeks. ARKO mice with or without Ang II stimulation showed a significant reduction in the heart-to-body weight ratio compared with those of WT mice. In addition, echocardiographic analysis demonstrated impairments of both the concentric hypertrophic response and left ventricular function in Ang II-stimulated ARKO mice. Western blot analysis of the myocardium revealed that activation of extracellular signal-regulated kinases (ERK) 1/2 and ERK5 by Ang II stimulation were lower in ARKO mice than those of WT mice. Ang II stimulation caused more prominent cardiac fibrosis in ARKO mice than in WT mice with enhanced expression of types I and III collagen and transforming growth factor-β1 genes and with increased Smad2 activation. These results suggest that, in male mice, the androgen-AR system participates in normal cardiac growth and modulates cardiac adaptive hypertrophy and fibrosis during the process of cardiac remodeling under hypertrophic stress.

Heparin Cofactor II Is a Novel Protective Factor Against Carotid Atherosclerosis in Elderly Individuals

Background—Thrombin plays a crucial role in atherothrombotic changes. Because heparin cofactor II (HCII) inhibits thrombin actions after binding to dermatan sulfate at injured arterial walls, HCII may negatively regulate thrombin actions in vascular walls. We hypothesized that plasma HCII activity is a preventive factor against atherosclerotic changes, especially in elderly individuals who already have atherosclerotic vascular injuries. Methods and Results—Maximum plaque thickness (MPT) in the carotid artery was measured by ultrasonography in 306 Japanese elderly individuals (154 men and 152 women; age, 40 to 91 years; 68.9±11.1 years, mean±SD). The relevance of cardiovascular risk factors including plasma HCII activity to the severity of MPT was statistically evaluated. Plasma HCII activity decreased with age. Simple linear regression analysis after adjustments for age and sex showed that lipoprotein(a), glycosylated hemoglobin A1c, and presence of diabetes mellitus significantly contributed to an increase in MPT values (r =0.119, P <0.05; r =0.196, P <0.001; and r =0.227, P <0.0001, respectively). In contrast, high-density lipoprotein (HDL) cholesterol and HCII activity were negatively correlated with MPT values (r =−0.117, P <0.05, and r =−0.202, P <0.0005, respectively). Multiple regression analysis revealed that plasma HCII activity and HDL cholesterol independently contributed to the suppression of MPT values and that the antiatherogenic contribution of HCII activity was stronger than that of HDL cholesterol (P <0.001 and P <0.05, respectively). Conclusions—These results suggest that HCII can be a novel and independent antiatherogenic factor. Moreover, HCII is a stronger predictive factor than HDL cholesterol against carotid atherosclerosis in elderly individuals.

Improvement in left ventricular function in response to carvedilol is accompanied by attenuation of neurohumoral activation in patients with dilated cardiomyopathy.

BACKGROUND We sought to evaluate whether improvement in ejection fraction (EF) with carvedilol therapy is accompanied by improvement in neurohumoral factors. METHODS AND RESULTS Forty-two patients with dilated cardiomyopathy were given carvedilol for 3 to 5 months. Changes in EF, plasma atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and norepinephrine levels were determined. Iodine-123 metaiodobenzylguanidine (MIBG) images were also obtained before and after carvedilol therapy. Myocardial uptake of MIBG was calculated as the heart to mediastinal activity ratio (H/M). Storage and release of MIBG was calculated as percent myocardial MIBG washout rate (WR). We divided patients into 2 groups: 27 responders whose EF increased by more than 5% and 15 nonresponders whose EF increased by 5% or less. EF of responders increased by 15 +/- 5% and that of nonresponders by 1 +/- 4%. Although MIBG image-derived indexes of nonresponders remained unchanged, the delayed H/M (1.91 +/- 0.34 v 2.24 +/- 0.53, P < .01) and WR (49 +/- 11 v 39 +/- 9%, P < .01) of responders improved, respectively. The plasma ANP (51 +/- 50 v 27 +/- 24 pg/mL, P < .01) and BNP (194 +/- 197 v 49 +/- 62 pg/mL, P < .01) levels of responders decreased. The degree of changes in the plasma BNP level correlated with changes in EF (r = -.698, P < .01). CONCLUSION The improvement in EF with carvedilol therapy was proved to be accompanied by an improvement in neurohumoral factors.

Serum carboxy-terminal telopeptide of type I collagen (ICTP) as a surrogate marker for vulnerable plaques in atherosclerotic patients: A pilot study

Evaluation of atherosclerotic plaques depends on invasive intravascular ultrasonography (IVUS). Carboxy-terminal telopeptide of type I collagen (ICTP) is produced by matrix metalloproteinase (MMP)-dependent digestion of type I collagen. Because vulnerable plaques are rich in type I collagen and MMPs from macrophages, we examined the association between serum ICTP and coronary plaques in patients with coronary disease. We recruited 46 men and 17 women without renal failure or bone diseases affecting serum ICTP, who underwent coronary IVUS. Serum ICTP levels were higher in patients with coronary plaques containing more than 10% necrotic core area than in patients with less than 10% necrotic core area. A positive correlation was found between serum ICTP and necrotic core area. Only serum ICTP was positively correlated with necrotic core area by multivariate analysis (p < 0.05). These results suggest that serum ICTP can be used as a non-invasive marker of vulnerable plaques in atherosclerotic patients.

Decrease in plasma brain natriuretic peptide level in the early phase after the start of carvedilol therapy is a novel predictor of long-term outcome in patients with chronic heart failure.

Objective — The purpose of the present study was to determine whether change in plasma brain natriuretic peptide (BNP) level at an early phase of carvedilol therapy is a predictor of improvement in cardiac function and long-term prognosis in patients with systolic chronic heart failure (CHF). Methods and results — Neurohumoral factors and haemodynamics were examined in 64 patients with systolic CHF (left ventricular ejection fraction (LVEF) below 45%) before and one month (early phase) and 3 to 6 months (late phase) after the start of carvedilol therapy.These patients were followed up for a mean period of 57 months. Plasma BNP levels were already decreased in the early phase before improvement of LVEF in response to carvedilol therapy. Univariate and multivariate linear regression analyses showed that D log brain natriuretic peptide (BNP)E (= log BNP at baseline – log BNP at early phase) (P< 0.0001) was a significant independent predictor of improvement in LVEF in the late phase. Cardiac events occurred in 11 patients during the follow-up period. In addition, multivariate Cox proportional hazards regression analysis showed that D log BNPE (P= 0.0045) and systolic blood pressure at baseline (P=-0.048) were significant independent predictors of the development of cardiac events. Conclusions — Decrease in plasma BNP level in the early phase of carvedilol therapy is a novel predictor of not only improvement of LVEF in the late phase but also prognosis in patients with systolic CHF.

Aggressive Antiplatelet Therapy Before Coronary Stent Implantation in Acute Coronary Syndrome with Essential Thrombocythemia A Case Report

A 52-year-old man was admitted to the hospital because of unstable angina pectoris. Coronary angiography revealed severe stenosis at a proximal site of the left anterior descending artery. Essential thrombocythemia (ET) was diagnosed on the basis of findings of marked thrombo cytosis (106 x 104/μL) and an increased number of immature megakaryocytes in the bone marrow. Because hyperaggregability of platelets was demonstrated by an ex vivo platelet aggregation assay and by elevated plasma levels of β-thromboglobulin (β-TG) and platelet factor 4 (PF4), antiplatelet therapy with aspirin and ticlopidine and cytoreduction therapy with hydroxyurea were started. This combination treatment resulted in a decrease in the platelet count to less than 60 x 104/μL and decreases in plasma levels of both β-TG and PF4 to almost normal values. Percutaneous coronary angioplasty and stenting were then performed success fully without thrombotic complications. These findings suggest that combination therapy with antiplatelet and cytoreduction agents before catheter intervention is useful for the prevention of thrombotic complications in patients with acute coronary syndrome associated with essential thrombocythemia.

Increase in serum triglyceride was associated with coronary plaque vulnerability in a patient with rheumatoid arthritis

Rates of morbidity and mortality from cardiovascular disease are high in patients with rheumatoid arthritis (RA); however, the mechanisms and biomarkers that reflect coronary plaque vulnerability have not yet been established. We present a case of acute coronary syndrome (ACS) presumably caused by exacerbation of chronic inflammation of RA, in which an abrupt increase in serum triglyceride was seen on the day of onset of ACS but not during effort angina. This case suggests that RA patients with an abrupt increase in triglyceride need intensive care including anti-platelet and statin therapy for the prevention of coronary plaque rupture. <Learning objective: Triglyceride might be a sensitive biomarker of activated macrophages and plaque vulnerability in patients with RA. RA patients with an abrupt increase in triglyceride might need intensive care including anti-platelet and statin therapy for the prevention of coronary plaque rupture.>.