Objectives-Enhanced osteoclastogenesis, increased bone resorption, and osteoporosis have been reported in osteoprotegerin-deficient (OPG (Ϫ/Ϫ)) mice. OPG (Ϫ/Ϫ) mice available in Japan usually do not show vascular calcification. We have found that arterial calcification can be quickly induced by a simple procedure in OPG (Ϫ/Ϫ) mice. Methods and Results-Male OPG (Ϫ/Ϫ), OPG (ϩ/Ϫ), and OPG (ϩ/ϩ) mice were fed a high phosphate diet from 6 to 10 weeks after birth, and then 1␣,25-dihydroxyvitamin D3 (calcitriol) was injected for 3 days. We found that severe calcification developed in the media of the aorta in OPG (Ϫ/Ϫ) mice. Under electron microscopy, calcium deposits were observed in the cytoplasm and extracellular matrix of vascular smooth muscle cells (VSMCs Key Words: osteoprotegerin Ⅲ alkaline phosphate Ⅲ vascular smooth muscle cells Ⅲ calcium deposits V ascular calcification, which is frequently observed in patients with end-stage renal disease, diabetes, aging, and osteoporosis, can also lead to cardiovascular diseases and even sudden death. 1-3 Until recently, vascular calcification was considered to be a passive process that occurred as a nonspecific response to tissue injury or necrosis. Now it is becoming increasingly clear that vascular calcification is an actively regulated process that resembles bone metabolism and involves alkaline phosphatase (ALP) and other bonerelated proteins. 4 -7 Osteoprotegerin (OPG) is abundantly produced by osteoblasts at the bone surface and inhibits osteoclast activity, working as a key regulator of bone homeostasis. 8,9 Since it has been reported that OPG (Ϫ/Ϫ) mice exhibit severe osteoporosis attributable to enhanced osteoclastogenesis, OPG is considered to be a protective factor in bone metabolism. 10,11 In the vasculature, the function of OPG is unknown because it is unclear whether vascular calcification takes place in OPG (Ϫ/Ϫ) mice or not. 10,11 Moreover, it was reported that the serum OPG level is associated with the presence and severity of coronary artery disease (CAD). 12 It remains to be clarified whether OPG is involved in the progression of CAD or whether the upregulation of serum OPG concentration is a compensatory mechanism. ALP is a crucial enzyme for initiating mineralization in bone and is present in systemic arteries, arterioles, and some capillaries. 13 It is possible that this enzyme plays a role in arterial calcification by the same mechanism of action as that in bone. 14 Activation of ALP in the arterial wall may result in enhanced vascular calcification.It is well known that either an elevated serum phosphate level or treatment with high doses of vitamin D induces vascular calcification in animal models as well as in humans. 15,16 In the present study, using OPG (Ϫ/Ϫ) mice, we established a mouse model in which arterial calcification can be quickly induced by treatment with a high phosphate diet plus 1␣,25-dihydroxyvitamin D3 (calcitriol) injection, and this model allowed us to perform detailed pathological and biochemical examinations at desired tim...

Abstract-Bach1 is a stress-responsive transcriptional factor that is thought to control the expression levels of cytoprotective factors, including heme-oxygenase (HO)-1. In the present study, we investigated the roles of Bach1 in the development of left ventricular (LV) hypertrophy and remodeling induced by transverse aortic constriction (TAC) in vivo using Bach1 gene-deficient (Bach1 Ϫ/Ϫ ) mice. TAC for 3 weeks in wild-type control (Bach1 ϩ/ϩ ) mice produced LV hypertrophy and remodeling manifested by increased heart weight, histological findings showing increased myocyte cross-sectional area (CSA) and interstitial fibrosis (picro Sirius red staining), reexpressions of ANP, BNP, and ␤MHC genes, and echocardiographic findings showing wall thickening, LV dilatation, and reduced LV contraction. Deletion of Bach1 caused significant reductions in heart weight (by 16%), CSA (by 36%), tissue collagen content (by 38%), and gene expression levels of ANP (by 75%), BNP (by 45%), and ␤MHC (by 74%). Echocardiography revealed reduced LV dimension and ameliorated LV contractile function. Deletion of Bach1 in the LV caused marked upregulation of HO-1 protein accompanied by elevated HO activity in both basal or TAC-stimulated conditions. Treatment of Bach1 Ϫ/Ϫ mice with tin-protoporphyrin, an inhibitor of HO, abolished the antihypertrophic and antiremodeling effects of Bach1 gene ablation. These results suggest that deletion of Bach1 caused upregulation of cytoprotective HO-1, thereby inhibiting TAC-induced LV hypertrophy and remodeling, at least in part, through activation of HO. Bach1 repressively controls myocardial HO-1 expression both in basal and stressed conditions, inhibition of Bach1 may be a novel therapeutic strategy to protect the myocardium from pressure overload. Key Words: hypertrophy Ⅲ HO-1 Ⅲ mice Ⅲ oxidative stress Ⅲ Bach1 Ⅲ remodeling C ardiac hypertrophy has been regarded as a compensatory mechanism of the heart to maintain cardiac output during pathological states with sustained increases in hemodynamic load, but it is associated with a high risk of cardiac mortality because of its established role in the development of cardiac failure. Heme-oxygenase (HO) is an enzyme that degrades prooxidant heme to carbon monoxide and biliverdin/bilirubin. HO-1 is an inducible form and HO-2 is a constitutive form of the enzyme. 1 HO-1, the activity of which is 10-fold greater than that of HO-2, is considered to be a stress-induced cytoprotective factor because (1) it is swiftly upregulated on exposure to cellular stress and (2) the catalytic products, carbon monoxide and biliverdin/bilirubin, have antiinflammatory 2 and antioxidant 3 actions, respectively. In the left ventricle (LV), stresses such as pressure overload cause generation of reactive oxygen species (ROS) and inflammatory reaction, which are thought to be involved in the underlying mechanisms of LV hypertrophy and the subsequent process of LV remodeling. 4 HO-1 may be activated in the LV in such stressed conditions, attenuating the effects of prohypertrophic R...

This study was designed to determine whether Bach1 gene ablation leads to suppression of atherosclerosis in apolipoprotein E (Apo E)/Bach1 double knockout (DKO) mice. Apo E/Bach1 DKO mice were generated by intercrossing Apo E knockout (KO) and Bach1 KO mice. The animals were fed a high-fat diet for 8 weeks, and the atherosclerotic plaques in the thoracic and abdominal aorta were visualized by oil red O staining.In DKO mice, the total plaque area was reduced by 32% compared with that in Apo E KO mice. In DKO mice,

Elevated levels of arterial lactate on admission were related to worse in-hospital mortality in patients with ADHF either with or without ACS, suggesting that the presence of high lactate in patients who enter the ICU with ADHF could help stratify the initial risk of early mortality.