Fetuin-A is associated with calcified coronary artery disease.

OBJECTIVE: Fetuin-A is a circulating glycoprotein that is involved in various stages of atherosclerosis. Despite the fact that emerging evidence suggests fetuin-A acts as a calcification inhibitor that protects against advanced calcified atherosclerosis in dialyzed patients, the role of fetuin-A in cardiovascular disease is still controversial. As diabetes and uremia make the role of fetuin-A in cardiovascular disease uncertain, we investigated the association between fetuin-A and calcified coronary artery disease in participants without diabetes and renal dysfunction. METHODS: Serum fetuin-A levels were measured in 92 participants who underwent coronary angiography. The number of diseased vessels and the presence of calcification were evaluated. RESULTS: Fetuin-A levels significantly decreased in patients with advanced three-vessel disease compared with those without stenosis (245.5+/-50.9, 289.0+/-71.8 microg/ml, respectively; P<0.05). Likewise, fetuin-A levels were significantly lower in patients with coronary artery calcification compared with those without coronary artery calcification (257.1+/-49.7, 288.0+/-63.1 microg/ml, respectively; P = 0.010). Multivariate logistic regression analysis revealed that fetuin-A levels inversely correlated with the presence of coronary artery calcification (odds ratio: 0.54; 95% confidence interval: 0.31-0.92; P = 0.025). CONCLUSION: Serum fetuin-A levels inversely correlated with advanced calcified coronary artery disease.

Association of serum TRAIL level with coronary artery disease.

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF ligand family, and is able to induce apoptosis in tumor cells. Emerging experimental findings suggest the involvement of TRAIL in vascular biology and atherosclerosis. However, little is known concerning the role of TRAIL in atherosclerosis in humans. We therefore examined whether serum TRAIL levels are associated with coronary artery disease (CAD). Serum TRAIL levels were measured by ELISA in 285 patients who underwent coronary angiography. Serum TRAIL level was significantly lower in patients with CAD (659.2+/-176.6 pg/ml) than in those without CAD (732.3+/-187.9 pg/ml, p=0.0016). Next, the number of diseased vessels was used to represent the severity of CAD. Serum TRAIL levels were inversely associated with the severity of CAD (p for trend=0.0005). In particular, TRAIL levels in patients with severe 3-vessel disease were significantly lower than those in subjects without CAD (602.9+/-150.0, 732.3+/-187.9 pg/ml, respectively; p<0.05). Multivariable logistic regression analysis revealed that serum TRAIL levels were significantly associated with the presence of CAD (odds ratio, 0.68; 95% confidence interval 0.51-0.90; p=0.006). Serum TRAIL levels were inversely associated with the advanced CAD, suggesting that TRAIL may be useful as a biomarker of CAD severity.

Effects of pravastatin on serum osteoprotegerin levels in patients with hypercholesterolemia and type 2 diabetes.

Osteoprotegerin is a secretory glycoprotein. Recent experimental findings have suggested that osteoprotegerin may protect against vascular calcification and/or atherosclerosis. In humans, osteoprotegerin levels are positively correlated with the presence and severity of coronary artery disease and the progression of atherosclerosis. However, it is unclear how osteoprotegerin levels are regulated. Statins are known to have beneficial pleiotropic effects against atherosclerosis beyond their lipid-lowering effects. In this study, we examined whether treatment with pravastatin can alter osteoprotegerin levels in patients with hypercholesterolemia and type 2 diabetes. Osteoprotegerin levels were significantly increased from 6.64 +/- 2.18 pmol/L at baseline to 7.08 +/- 2.29 pmol/L (P = .024) after 3-month treatment with pravastatin. These increases in osteoprotegerin levels remained after 6 months of treatment (7.05 +/- 2.22 pmol/L, P = .026). These findings suggest that pravastatin may exert its pleiotropic effects in part through alteration of osteoprotegerin levels.

[Calcified coronary artery disease and serum markers].

Severity of coronary artery calcification is closely related to atherosclerotic plaque burden and cardiac event rate. Recent data have suggested that vascular calcification is an actively regulated process similar to the bone formation, and that bone-related factors may be involved in the development of vascular calcification. Non-invasive prediction of calcified coronary artery disease is important using serum bone-related markers. Among them, we focus on matrix Gla protein, osteoprotegerin and fetuin-A as such candidates in this review.

Vascular calcification in chronic kidney disease.

Vascular calcification is often encountered in advanced atherosclerotic lesions and is a common consequence of aging. Calcification of the coronary arteries has been positively correlated with coronary atherosclerotic plaque burden, increased risk of myocardial infarction, and plaque instability. Chronic kidney disease (CKD) patients have two to five times more coronary artery calcification than healthy age-matched individuals. Vascular calcification is a strong prognostic marker of cardiovascular disease mortality in CKD patients. Vascular calcification has long been considered to be a passive, degenerative, and end-stage process of atherosclerosis and inflammation. However, recent evidence indicates that bone matrix proteins such as osteopontin, matrix Gla protein (MGP), and osteocalcin are expressed in calcified atherosclerotic lesions, and that calcium-regulating hormones such as vitamin D3 and parathyroid hormone-related protein regulate vascular calcification in in vitro vascular calcification models based on cultured aortic smooth muscle cells. These findings suggest that vascular calcification is an actively regulated process similar to osteogenesis, and that bone-associated proteins may be involved in the development of vascular calcification. The pathogenesis of vascular calcification in CKD is not well understood and is almost multifactorial. In CKD patients, several studies have found associations of both traditional risk factors, such as hypertension, hyperlipidemia, and diabetes, and uremic-specific risk factors with vascular calcification. Most patients with progressive CKD develop hyperphosphatemia. An elevated phosphate level is an important risk factor for the development of calcification and cardiovascular mortality in CKD patients. Thus, it is hypothesized that an important regulator of vascular calcification is the level of inorganic phosphate. In order to test this hypothesis, we characterized the response of human smooth muscle cell (HSMC) cultures to inorganic phosphate levels. Our findings indicate that inorganic phosphate directly regulates HSMC calcification through a sodium-dependent phosphate transporter mechanism. After treatment with elevated phosphate, there is a loss of smooth muscle lineage markers, such as alpha-actin and SM-22alpha, and a simultaneous gain of osteogenic markers such as cbfa-1 and osteocalcin. Elevated phosphate may directly stimulate HSMC to undergo phenotypic changes that predispose to calcification, and offer a novel explanation of the phenomenon of vascular calcification under hyperphosphatemic conditions. Furthermore, putative calcification inhibitory molecules have been identified using mouse mutational analyses, including MGP, beta-glucosidase, fetuin-A, and osteoprotegerin. Mutant mice deficient in these molecules present with enhanced cardiovascular calcification, demonstrating that specific molecules are normally important in suppressing vascular calcification. These findings suggest that the balance of inducers, such as phosphate, and inhibitors, such as MGP, fetuin-A, and others, are likely to control whether or not calcification occurs under pathological conditions.

Serum levels of 1-84 and 7-84 parathyroid hormone in predialysis patients with chronic renal failure measured by the intact and bio-PTH assay.

BACKGROUND: The intact parathyroid hormone (PTH) assay detects both PTH(1-84) and the PTH(7-84)-like fragment, which is reported to be an antagonist of the biological action of PTH(1-84). It is debatable which of the two assays is clinically more useful, the intact or bio-PTH assay, the latter of which only detects PTH(1-84). It is also unknown whether serum levels of the PTH(7-84)-like fragment have clinical significance. METHODS: Serum PTH concentrations in 104 predialysis patients with chronic renal failure (CRF; serum creatinine 3.53 +/- 1.93; 62 males and 42 females; 61.0 +/- 11.5 years old) were measured using both the intact and bio-PTH assays, and the concentration of the PTH(7-84)-like fragment was calculated by subtracting bio-PTH from intact PTH. Three bone formation and three bone resorption markers were measured simultaneously. RESULTS: The PTH values measured using the two assays were strongly positively correlated (r = 0.959, p < 0.0001), and were also significantly positively correlated with the three bone formation and three bone resorption markers to a similar degree. The PTH(7-84)-like fragment was significantly positively correlated with both the intact and bio-PTH (r = 0.855, p < 0.0001 for intact PTH; r = 0.672, p < 0.0001 for bio-PTH), and was also significantly positively correlated with each of the six bone metabolism markers. There is no significant relationship between the bio-PTH/PTH(7-84)-like fragment ratio and clinical parameters including bone metabolic markers. CONCLUSION: From the strong relationship between the two assays, and the similar degree of the relationship between each PTH assay and each of the six bone metabolism markers, it is considered that the bio-PTH and intact PTH assays have similar clinical significance in predialysis CRF patients. Serum levels of the PTH(7-84)-like fragment seem to increase as serum PTH(1-84) increases. The results suggest that the serum PTH(7-84)-like fragment has little specific clinical effect on bone metabolism, even when assessed by the ratio of bio-PTH/PTH(7-84)-like fragment.

[Clinical significance of PTH (1-84) and PTH (7-84) in patients with predialysis chronic renal failure in relation to bone metabolism markers].

Serum levels of parathyroid hormone (PTH) in predialysis patients with chronic renal failure (CRF) were measured using both the "intact PTH" and "bio PTH" assays, and serum levels of PTH (7-84) were assessed by subtracting bio PTH from intact PTH. The PTH values measured by the two assays were strongly correlated, and were also significantly positively correlated with both bone formation and resorption markers. PTH (7-84) was significantly positively correlated with both the intact PTH and bio PTH, and was also significantly positively correlated with the bone metabolism markers. There is no significant relationship between bio PTH/PTH (7-84) ratio and bone metabolism markers. In conclusion, bio PTH and intact PTH assays have similar clinical significance in predialysis CRF patients. The PTH (7-84) and even the ration of bio-PTH/PTH (7-84) have little specific clinical effect on bone metabolism.

Cross-sectional association of serum phosphate with carotid intima-medial thickness in hemodialysis patients.

BACKGROUND: Although an increased serum phosphate concentration is a significant risk factor for vascular calcification, it is unclear whether serum phosphate level is a risk factor for increased arterial wall thickness in hemodialysis patients. METHODS: Using B-mode ultrasonography, we examined intima-medial thickness (IMT) of the carotid artery of hemodialysis patients and analyzed risk factors for increased IMT with regard to the effect of serum phosphate. Seven hundred sixteen hemodialysis patients were enrolled (547 patients without diabetes, 169 patients with diabetes; 441 men, 275 women; age, 60 +/- 8.5 years). RESULTS: IMT of patients with diabetes was significantly greater than that of patients without diabetes (0.859 +/- 0.250 versus 0.783 +/- 0.178 mm; P < 0.0001). For the group of all patients, IMT correlated weakly, but significantly, with serum phosphate level (r = 0.093; P = 0.0127). In multiple regression analysis of the group of all patients, greater serum phosphate level (beta = 0.166; P < 0.0001) was shown to be a significant independent risk factor for increased carotid IMT, in addition to other significant independent risk factors, including advanced age, higher blood pressure, greater non-high-density lipoprotein cholesterol level, and the presence of diabetes (R2 = 0.1119; P < 0.00001). In multiple regression analyses performed separately for hemodialysis patients without and with diabetes, greater phosphate level and advanced age were significant independent risk factors for increased IMT, independent of other confounding risk factors. CONCLUSION: These results show that in addition to advanced age, greater serum phosphate level is a significant and independent factor associated with advanced arteriosclerosis in hemodialysis patients with and without diabetes, suggesting that phosphate levels should be controlled appropriately to prevent an increase in arterial wall thickness in hemodialysis patients.

Increased levels of serum osteoprotegerin in hypothyroid patients and its normalization with restoration of normal thyroid function.

Hypothyroidism is associated with increased morbidity from cardiovascular disease, and an increase in serum osteoprotegerin (OPG) has recently been reported to be associated with the severity of coronary heart disease and cardiovascular mortality. The present study was designed to examine whether hypothyroidism causes an increase in serum OPG, and to determine whether levothyroxine (L-T4) replacement therapy might suppress serum OPG levels in hypothyroid patients. Fifty-three hypothyroid patients with chronic thyroiditis and age- and sex-matched normal control subjects were examined for the levels of serum OPG and plasma von Willebrand factor (vWF), a vascular injury marker. Thirty-seven of the hypothyroid patients were further monitored for changes in these markers during 1 year in a euthyroid state induced by L-T4 replacement therapy. Baseline OPG was significantly higher in hypothyroid patients than in normal controls (4.51 +/- 0.50 vs 3.72 +/- 0.23 pmol/l (mean +/- S.E.); P = 0.0182). In multivariate analysis, baseline OPG was significantly associated with baseline levels of TSH (r = 0.280, P = 0.0162) and vWF (r = 0.626, P < 0.0001). During one year of L-T4 replacement therapy, hypothyroid patients showed a significant decrease in OPG levels from 4.35 +/- 0.51 to 3.48 +/- 0.26 pmol/l (P = 0.0166), a level comparable to normal controls. The change in serum OPG levels during L-T4 replacement therapy was significantly and independently associated in a negative fashion with baseline vWF (r = -0.503, P = 0.0014). This study suggested that the severity of hypothyroidism and vascular injury might have important independent roles in increasing the serum OPG level in hypothyroid patients. Furthermore, it was demonstrated that a sustained euthyroid state might have the potential to decrease the serum OPG level in hypothyroid patients and that the degree of vascular injury in the hypothyroid state is independently associated with a decrease in serum OPG during a 1-year normalization of thyroid function.

Hyperphosphatemia and vascular calcification in end-stage renal disease.

Vascular calcification is a common finding in atherosclerosis and a serious problem in uremic patients. Because of the correlation of hyperphosphatemia and vascular calcification, the ability of extracellular inorganic phosphate levels to regulate human aortic smooth muscle cell (HSMC) culture mineralization in vitro was examined. HSMC cultured in media containing normal physiologic levels of inorganic phosphate (1.4 mM) did not mineralize. In contrast, HSMC cultured in media containing phosphate levels comparable with those seen in hyperphosphatemic individuals (>1.4 mM) showed dose-dependent increases in mineral deposition. Mechanistic studies showed that elevated phosphate treatment of HSMC also enhanced the expression of the osteoblastic differentiation markers osteocalcin and osf2/Cbfa-1. The effects of elevated phosphate on HSMC were mediated by a sodium-dependent phosphate cotransporter (NPC) as indicated by the ability of the specific NPC inhibitor phosphonoformic acid to dose-dependently inhibit phosphate-induced calcium deposition as well as osteocalcin and Cbfa-1 gene expression. The NPC in HSMC was identified as Pit-1, a member of the novel type III NPCs. These data suggest that elevated phosphate may directly stimulate HSMC to undergo phenotypic changes that predispose to calcification and offers a novel explanation of the phenomenon of vascular calcification under hyperphosphatemic conditions. Furthermore, we examined the factors affecting peripheral vascular calcification in 332 nondiabetic hemodialysis patients. There were 45 nondiabetic patients with vascular calcification. In multivariate logistic regression, the significant factors affecting vascular calcification were advanced age, longer duration of hemodialysis, increased phosphate concentrations, male gender, and lower predialysis diastolic pressure. Our findings suggest that an elevated phosphate level may directly stimulate HSMC to undergo phenotypic changes that predispose to calcification and offer a novel explanation of the phenomenon of vascular calcification under hyperphosphatemic conditions.

The clinical significance of serum osteocalcin and N-terminal propeptide of type I collagen in predialysis patients with chronic renal failure.

Several new serum markers for bone metabolism have recently become available and are being applied to clinical practice. Their clinical usefulness in predialysis patients with chronic renal failure (CRF), however, has not yet been determined. Serum levels of three bone formation markers-bone alkaline phosphatase (BAP), osteocalcin (OC), and N-terminal propeptide of type I collagen (PINP)-and three bone resorption markers-type I collagen cross-linked N-telopeptide (NTx), deoxypyridinoline (DPD), and pyridinoline (PYD)-were measured simultaneously in 85 predialysis CRF patients (serum creatinine 3.5 +/- 1.9 mg/dl, 61.0 +/- 10.9 years old, 54 males and 31 females, 36 diabetics and 49 nondiabetics) to examine the relationships between these markers and bone mineral density (BMD) of the distal radius, as measured by peripheral quantitative computed tomography (pQCT). Trabecular BMD, which is strongly affected by bone metabolism, was significantly negatively correlated with each of the bone formation markers (r=-0.341, p=0.0016, for OC; r=-0.314, p=0.0036, for PINP; r=-0.238, p=0.0315, for BAP), but there was no significant correlation between BMD and any of the bone resorption markers. In multivariate regression analyses (adjusted by age, sex, presence of diabetes, glomerular filtration rate, intact parathyroid hormone, calcium, phosphate, and 1,25-dihydroxyvitamin D), OC and PINP were significantly associated with a decrease in BMD, but BAP was not. In conclusion, we demonstrated that in predialysis CRF patients, BMD of the distal radius, particularly of trabecular bone, is associated with serum OC and PINP levels. OC and PINP are suggested to be possible parameters for the clinical evaluation of the effect of bone metabolism on BMD.

[Risk factors of atherosclerosis in end-stage renal disease patients].

Patients with end-stage renal disease have greatly elevated risks of atherosclerotic disease. Vascular calcification in advanced atherosclerosis is a common feature in ESRD patients. Risk factors of atherosclerosis in ESRD patients are coronary risk factors such as hypertension, diabetes and hyperlipidemia and hyperphosphatemia. Bone associated proteins including osteopontin, matrix Gla protein and osteoprotegerin may be involved in the progression of atherosclerosis.

[Mechanism of vascular calcification].

Vascular calcification in dialysis patients is associated with morbidity and mortality risks. Recent evidence suggests that vascular calcification is an active process resembling osteogenesis and chondrogenesis process. In this process, hyperphosphatemia is one of the important regulators. Inorganic phosphates directly regulate vascular calcification in vitro through a sodium-dependent phosphate cotransporter and promote expression of the osteoblastic differentiation markers.

C-reactive protein is a significant predictor of vascular calcification of both aorta and hand arteries.

Although evidence has accumulated indicating a close relationship between inflammation and atherosclerosis, the relationship between inflammation and vascular calcification in patients with chronic renal failure is unclear. In the present study, the relationship between C-reactive protein (CRP) and vascular calcification in dialysis patients was examined. Vascular calcification of the aorta and hand arteries of 512 hemodialysis patients without significant infection (age 58.8 +/- 10.1 y; 305 men, 207 women) were examined by roentgenography of the lateral abdomen and hands, respectively. Patients with a mean CRP level greater than 1.0 mg/L (n = 254) were older than those with a CRP level less than or equal to 1.0 mg/L (n = 258) and had a longer duration of dialysis, lower serum albumin level, and higher phosphate level ( P < .01, P < .05, P < .001, and P < .01, respectively). Prevalence of vascular calcification of aorta and hand arteries in the former group was significantly higher than in the latter (65.0% versus 43.8% for aorta, P < .0001; and 25.0% versus 14.7% for hand arteries, P < .01). In a multivariate logistic regression analysis adjusted for age, hemodialysis duration, sex, levels of calcium and phosphate, and presence of diabetes, CRP level was a significant predictor for the presence of aortic calcification (odds ratio for highest versus lowest quartile, 2.669; 95% confidence interval, 1.539-5.421, P = .0010) and of calcification of hand arteries (odds ratio, 2.243; 95% confidence interval, 1.039-4.841; P = .0395). In conclusion, the present study shows that increased levels of CRP are significantly associated with the presence of vascular calcification in both aorta and hand arteries (ie, with both atheromatous and medial forms of calcification), indicating evidence for a relationship between inflammation and vascular calcification in hemodialysis patients.

Statins inhibit in vitro calcification of human vascular smooth muscle cells induced by inflammatory mediators.

Although lipid-lowering therapy with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) decreases the progression of coronary artery and aortic valve calcification, the mechanism of action of these drugs to inhibit the calcification process remains unclear. In this study, we investigated the effect of statins such as cerivastatin and atorvastatin on vascular calcification by utilizing an in vitro model of inflammatory vascular calcification. Cerivastatin and atorvastatin dose-dependently inhibited in vitro calcification of human vascular smooth muscle cells (HVSMCs) induced by the following inflammatory mediators (IM): interferon-gamma, 1alpha,25-dihydroxyvitamin D3, tumor necrosis factor-alpha, and oncostatin M. These statins also depressed expression of alkaline phosphatase (ALP) in HVSMCs induced by these factors. Mevalonate and geranylgeranylpyrophosphate reversed the inhibitory effect of cerivastatin on ALP expression in HVSMCs, while farnesylpyrophosphate showed no effect on the ALP activities inhibited by this drug, suggesting that inhibition of Rho and its downstream target, Rho kinase may mediate the inhibitory effect of cerivastatin. Cerivastatin prevented RhoA activation in HVSMCs induced by the IM. A specific inhibitor of Rho kinase (Y-27632) inhibited in vitro calcification and induction of ALP in HVSMCs. These findings provide a possible mechanism of statins to prevent the progression of calcification in inflammatory vascular diseases such as atherosclerosis and cardiac valvular calcification.

Matrix Gla protein is associated with coronary artery calcification as assessed by electron-beam computed tomography.

Matrix Gla protein (MGP) is an extracellular matrix protein with wide tissue distribution. It has been demonstrated that the expression of MGP is detected not only in the normal blood vessels but also calcified atherosclerotic plaques, and that MGP deficient mice develop extensive arterial calcification. MGP is thought to be a regulator of vascular calcification. A recent clinical study demonstrates the association between polymorphisms of the MGP gene and increased risk of myocardial infarction. However, there are no reports of the relationship between serum MGP levels and coronary artery calcification (CAC). We evaluated the severity of CAC using electron-beam computed tomography (EBCT), and measured serum MGP levels by enzyme-linked immunosorbent assay in 115 subjects with suspected coronary artery disease. CAC scores were correlated with traditional risk factors, such as age, gender, hyper-tension, diabetes, hyperlipidemia and smoking. The serum MGP levels were lower in patients with CAC than in those without CAC (p<0.001). As the severity of CAC increased, there was a significant decrease in serum MGP levels. Serum MGP levels (U/L) were 116.7 +/- 20.3, 104.9 +/- 19.2, 95.2 +/- 15.2 and 82.2 +/- 19.7, (medians 115.5, 105.0, 94.8, and 81.9) for the subjects with normal (CAC score=0), mild (CAC score=1 to 99), moderate (CAC score=100 to 400), and severe (CAC score >400) coronary calcification, respectively. We found that serum MGP levels are inversely correlated with the severity of CAC. These data suggest a possible role for MGP in the development of vascular calcification.

Serum osteoprotegerin levels are associated with the presence and severity of coronary artery disease.

BACKGROUND: Osteoprotegerin (OPG) is a secretory glycoprotein that belongs to the tumor necrosis factor receptor family. OPG-deficient mice develop severe osteoporosis and medial arterial calcification of the aorta and renal arteries. OPG immunoreactivity was demonstrated in the normal blood vessels and in early atherosclerotic lesions. A recent clinical study suggests that there is a significant correlation between elevated serum OPG levels and cardiovascular mortality. We examined whether serum OPG levels are associated with the progression of coronary artery disease (CAD). METHODS AND RESULTS: Serum OPG levels were examined in 201 patients who underwent coronary angiography because of stable chest pain. The number of diseased vessels was used to represent the severity of CAD. Serum OPG levels were measured by ELISA and were significantly greater in patients with significant stenosis of the coronary arteries than in those without stenosis. As the severity of CAD increased, there was a significant increase in serum OPG levels. Serum OPG levels were 0.94+/-0.34, 1.04+/-0.38, 1.19+/-0.38, and 1.44+/-0.54 ng/mL (medians 0.91, 0.99, 1.09, and 1.37) for the subjects with normal coronary arteries or luminal irregularities, 1-vessel disease, 2-vessel disease, and 3-vessel disease, respectively. Multivariate logistic regression analysis revealed that serum OPG levels were significantly associated with the presence of CAD [odds ratio, 5.2; 95% confidence interval, 1.7 to 16.0]. CONCLUSIONS: Our data show that serum OPG levels are associated with the presence and severity of CAD, suggesting that OPG may be involved in the progression of CAD.

Induction of bone-type alkaline phosphatase in human vascular smooth muscle cells: roles of tumor necrosis factor-alpha and oncostatin M derived from macrophages.

Inflammatory cells such as macrophages and T lymphocytes play an important role in vascular calcification associated with atherosclerosis and cardiac valvular disease. In particular, macrophages activated with cytokines derived from T lymphocytes such as interferon-gamma (IFN-gamma) may contribute to the development of vascular calcification. Moreover, we have shown the stimulatory effect of 1alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) on in vitro calcification through increasing the expression of alkaline phosphatase (ALP), an ectoenzyme indispensable for bone mineralization, in vascular smooth muscle cells. Therefore, we hypothesized that macrophages may induce calcifying phenotype, especially the expression of ALP in human vascular smooth muscle cells (HVSMCs) in the presence of IFN-gamma and 1,25(OH)2D3. To test this hypothesis, we used cocultures of HVSMCs with human monocytic cell line (THP-1) or peripheral blood monocytes (PBMCs) in the presence of IFN-gamma and 1,25(OH)2D3. THP-1 cells or PBMCs induced ALP activity and its gene expression in HVSMCs and the cells with high expression of ALP calcified their extracellular matrix by the addition of beta-glycerophosphate. Thermostability and immunoassay showed that ALP induced in HVSMCs was bone-specific enzyme. We further identified tumor necrosis factor-alpha (TNF-alpha) and oncostatin M (OSM) as major factors inducing ALP in HVSMCs in the culture supernatants of THP-1 cells. TNF-alpha and OSM, only when applied together, increased ALP activities and in vitro calcification in HVSMCs in the presence of IFN-gamma and 1,25(OH)2D3. These results suggest that macrophages may contribute to the development of vascular calcification through producing various inflammatory mediators, especially TNF-alpha and OSM.

[Close relationship between bone and vasculature].

Cardiovascular disease and osteoporosis are major causes of morbidity and mortality in elderly and postmenopausal women. Vascular calcification is a common feature of atherosclerotic plaques and is regulated in a way similar to bone mineralization. Several studies revealed that atherosclerotic calcification is associated with bone loss in women. In this review, we focus on the new developments during the past year in relationship between bone and vasculature. Regulatory factors include matrix GLA protein, osteoprotegerin, klotho gene, bisphosphonates and statins.