vitamin-k-semiquinone-radical and Calcinosis

Accelerated and premature cardiovascular calcification is a hallmark of patients with chronic kidney disease (CKD) or end-stage renal disease (ESRD). The presence and the amount of cardiovascular calcification are among the driving forces of increased morbidity and mortality in renal patients. Cardiovascular calcification occurs at different sites, including the cardiac valves-a location that is of particular importance for both the patient and the treating physician. The correlation between degree of calcification and functional impairment is particularly close at the aortic valve, that is, the amount of calcification predicts the degree of stenosis. Calcific aortic stenosis (CAS) is the most prevalent valvular heart disease in Western societies. CAS is particularly prevalent in patients with underlying CKD or ESRD. CAS increases afterload and hence contributes to the widespread finding of left ventricular hypertrophy in CKD/ESRD patients. Medical treatment options to prevent the development and progression of CAS are limited. Hence, close surveillance and timely referral of patients for heart valve replacement therapy is a mainstay of current therapy. Novel treatment approaches, such as transcatheter aortic valve implantation, offer promising yet challenging options for elderly, comorbid, and often frail patients with CAS in combination with advanced CKD/ESRD.

Topics: Aortic Valve; Aortic Valve Stenosis; Calcinosis; Calcium-Regulating Hormones and Agents; Chelating Agents; Cinacalcet; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Renal Insufficiency, Chronic; Sevelamer; Transcatheter Aortic Valve Replacement; Vitamin K

Ectopic mineralization disorders comprise a broad spectrum of inherited or acquired diseases characterized by aberrant deposition of calcium crystals in multiple organs, such as the skin, eyes, kidneys, and blood vessels. Although the precise mechanisms leading to ectopic calcification are still incompletely known to date, various molecular targets leading to a disturbed balance between pro- and anti-mineralizing pathways have been identified in recent years. Vitamin K and its related compounds, mainly those post-translationally activated by vitamin K-dependent carboxylation, may play an important role in the pathogenesis of ectopic mineralization as has been demonstrated in studies on rare Mendelian diseases, but also on highly prevalent disorders, like vascular calcification. This narrative review compiles and summarizes the current knowledge regarding the role of vitamin K, its metabolism, and associated compounds in the pathophysiology of both monogenic ectopic mineralization disorders, like pseudoxanthoma elasticum or Keutel syndrome, as well as acquired multifactorial diseases, like chronic kidney disease. Clinical and molecular aspects of the various disorders are discussed according to the state-of-the-art, followed by a comprehensive literature review regarding the role of vitamin K in molecular pathophysiology and as a therapeutic target in both human and animal models of ectopic mineralization disorders.

Topics: Abnormalities, Multiple; Animals; Calcinosis; Cartilage Diseases; Genetic Diseases, Inborn; Hand Deformities, Congenital; Humans; Pulmonary Valve Stenosis; Vitamin K

Gla-rich protein (GRP) or unique cartilage matrix-associated protein (Ucma), the newest member of vitamin K dependent proteins, carries exceptionally high number of γ-carboxyglutamic acid (Gla) residues which contributes to its outstanding capacity of binding with calcium in the extracellular environment indicating its potential role as a global calcium modulator. Recent studies demonstrated a critical function of GRP in the regulation of different pathophysiological conditions associated with vascular and soft tissue calcification including cardiovascular diseases, osteoarthritis, inflammation, and skin and breast carcinomas. These findings established an important relationship between γ-carboxylation of GRP and calcification associated disease pathology suggesting a critical role of vitamin K in the pathophysiological features of various health disorders. This review for the first time summarizes all of the updated findings related to the functional activities of GRP in the pathogenesis of several diseases associated with vascular and soft tissue mineralization, osteoarthritis, inflammation, and carcinoma. The outcome of this review will improve the understanding about the role of GRP in the pathogenesis of tissue calcification and its associated health disorders, which should in turn lead to the design of clinical interventions to improve the condition of patients associated with these health disorders.

Topics: Animals; Calcinosis; Humans; Inflammation; Intercellular Signaling Peptides and Proteins; Intracellular Signaling Peptides and Proteins; Neoplasms; Osteoarthritis; Proteins; Vitamin K

In the past few decades vitamin K has emerged from a single-function "haemostasis vitamin" to a "multi-function vitamin." The use of vitamin K antagonists (VKA) inevitably showed that the inhibition was not restricted to vitamin K dependent coagulation factors but also synthesis of functional extrahepatic vitamin K dependent proteins (VKDPs), thereby eliciting undesired side effects. Vascular calcification is one of the recently revealed detrimental effects of VKA. The discovery that VKDPs are involved in vascular calcification has propelled our mechanistic understanding of this process and has opened novel avenues for diagnosis and treatment. This review addresses mechanisms of VKDPs and their significance for physiological and pathological calcification.

Topics: Animals; Anticoagulants; Biomedical Research; Blood Coagulation; Calcification, Physiologic; Calcinosis; Humans; Models, Biological; Vitamin K; Vitamin K Deficiency

The main purpose of anticoagulants is to diminish fibrin formation, thereby decreasing the risk of venous or arterial thrombosis. Vitamin K antagonist have been used for many decades in order to achieve reduced thrombotic risk, despite major drawbacks of this class of drugs such as cumbersome dossing and monitoring of anticoagulant status. To overcome these drawbacks of VKA, new classes of anticoagulants have been developed including oral anticoagulants for direct inhibition of either thrombin or factor Xa, which can be administrated in a fixed dose without monitoring. Coagulation factors can activate cellular protease-activated receptors, thereby inducing cellular processes as inflammation, apoptosis, migration, and fibrosis. Therefore, inhibition of coagulation proteases not only attenuates fibrin formation, but may also influence pathophysiological processes like vascular calcification and atherosclerosis. Animal models revealed that VKA therapy induced both intima and media calcification and accelerated plaque vulnerability, whereas specific and direct inhibition of thrombin or factor Xa attenuated atherosclerosis. In this review we provide an overview of old and new oral anticoagulants, as well discuss potential pleiotropic effects with regard to calcification and atherosclerosis. Although translation from animal model to clinical patients seems difficult at first sight, effort should be made to fully understand the clinical implications of long-term oral anticoagulant therapy on vascular side effects.

Topics: Animals; Anticoagulants; Antithrombins; Atherosclerosis; Atrial Fibrillation; Blood Coagulation Factors; Calcinosis; Coumarins; Disease Models, Animal; Disease Progression; Drug Monitoring; Enzyme Activation; Factor Xa Inhibitors; Hemorrhage; Humans; Practice Guidelines as Topic; Protease Inhibitors; Randomized Controlled Trials as Topic; Receptors, Proteinase-Activated; Stroke; Thrombosis; Vitamin K

Hepatic vitamin K-dependent proteins (e.g., Factors II, VII, IX and X) form part of the clotting cascade. Factor II (FII)/Prothrombin incorporates 10 Glu residues on the N-terminal region that are γ-carboxylated to Gla residues by the action of γ-glutamyl carboxylase to confer biological activity. Vitamin K is also required for the normal function of Matrix Gla Protein (MGP)--one of several non-clotting-related extra-hepatic vitamin K-dependent proteins. MGP is known to have protective action against vascular calcification--indeed it is a powerful tissue-bound inhibitory mechanism and can be found in blood vessel walls. The mature protein is also dependent on activation by γ-glutamyl carboxylase enzyme to convert Glu residues in its amino acid sequence to Gla. This reaction can only take place when the enzyme is activated in the presence of vitamin K. It is of great potential interest to investigate whether subtle deficiencies of vitamin K may, through its effect on the action of MGP, be a contributing factor to vascular calcification in CKD patients, in whom CV disease is greatly accelerated and in whom vascular calcification is not only common, but progresses aggressively, and is something for which as yet there is no clinically applicable remedy.

Topics: Adult; Aged; Biomarkers; Calcinosis; Female; Glomerular Filtration Rate; Humans; Male; Middle Aged; Protein Precursors; Prothrombin; Renal Insufficiency, Chronic; Vascular Diseases; Vitamin K; Vitamin K Deficiency

Seventeen vitamin K-dependent proteins have been identified to date of which several are involved in regulating soft-tissue calcification. Osteocalcin, matrix Gla protein (MGP), and possibly Gla-rich protein are all inhibitors of soft-tissue calcification and need vitamin K-dependent carboxylation for activity. A common characteristic is their low molecular weight, and it has been postulated that their small size is essential for calcification inhibition within tissues. MGP is synthesized by vascular smooth muscle cells and is the most important inhibitor of arterial mineralization currently known. Remarkably, the extrahepatic Gla proteins mentioned are only partly carboxylated in the healthy adult population, suggesting vitamin K insufficiency. Because carboxylation of the most essential Gla proteins is localized in the liver and that of the less essential Gla proteins in the extrahepatic tissues, a transport system has evolved ensuring preferential distribution of dietary vitamin K to the liver when vitamin K is limiting. This is why the first signs of vitamin K insufficiency are seen as undercarboxylation of the extrahepatic Gla proteins. New conformation-specific assays for circulating uncarboxylated MGP were developed; an assay for desphospho-uncarboxylated matrix Gla protein and another assay for total uncarboxylated matrix Gla protein. Circulating desphospho-uncarboxylated matrix Gla protein was found to be predictive of cardiovascular risk and mortality, whereas circulating total uncarboxylated matrix Gla protein was associated with the extent of prevalent arterial calcification. Vitamin K intervention studies have shown that MGP carboxylation can be increased dose dependently, but thus far only 1 study with clinical endpoints has been completed. This study showed maintenance of vascular elasticity during a 3-y supplementation period, with a parallel 12% loss of elasticity in the placebo group. More studies, both in healthy subjects and in patients at risk of vascular calcification, are required before conclusions can be drawn.

Topics: Animals; Calcification, Physiologic; Calcinosis; Calcium-Binding Proteins; Extracellular Matrix Proteins; Humans; Liver; Matrix Gla Protein; Muscle, Smooth, Vascular; Osteocalcin; Vitamin K

Vitamin K is required for the activity of various biologically active proteins in our body. Apart from clotting factors, vitamin K-dependent proteins include regulatory proteins like protein C, protein S, protein Z, osteocalcin, growth arrest-specific gene 6 protein, and matrix Gla protein. Glutamic acid residues in matrix Gla protein are γ-carboxylated by vitamin K-dependent γ-carboxylase, which enables it to inhibit calcification. Warfarin, being a vitamin K antagonist, inhibits this process, and has been associated with calcification in various animal and human studies. Though no specific guidelines are currently available to prevent or treat this less-recognized side effect, discontinuing warfarin and using an alternative anticoagulant seems to be a reasonable option. Newer anticoagulants such as dabigatran and rivaroxaban offer promise as future therapeutic options in such cases. Drugs including statins, alendronate, osteoprotegerin, and vitamin K are currently under study as therapies to prevent or treat warfarin-associated calcification. Copyright © 2011 Wiley Periodicals, Inc. The authors have no funding, financial relationships, or conflicts of interest to disclose.

Topics: Anticoagulants; Calcinosis; Diphosphonates; Heart Valve Diseases; Humans; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hyperbaric Oxygenation; Muscle, Smooth, Vascular; Osteoprotegerin; Vitamin K; Warfarin

Vitamin K was discovered early last century at the same time as the vitamin K-antagonists. For many years the role of vitamin K was solely ascribed to coagulation and coagulation was thought to be involved only at the venous blood side. This view has dramatically changed with the discovery of vitamin K-dependent proteins outside the coagulation cascade and the role of coagulation factors at the arterial side. Vitamin K-dependent proteins are involved in the regulation of vascular smooth muscle cell migration, apoptosis, and calcification. Vascular calcification has become an important independent predictor of cardiovascular disease. Vitamin K-antagonists induce inactivity of inhibitors of vascular calcification, leading to accelerated calcification. The involvement of vitamin K-dependent proteins such as MGP in vascular calcification make that calcification is amendable for intervention with high intake of vitamin K. This review focuses on the effect of vitamin K-dependent proteins in vascular disease.

Topics: Animals; Anticoagulants; Arterial Occlusive Diseases; Arteries; Blood Coagulation Factors; Blood Proteins; Calcinosis; Humans; Models, Cardiovascular; Vitamin K

Morbidity and mortality are massively increased in patients with chronic kidney disease (CKD) and patients with end-stage renale disease (ESRD). Bone disease (renal osteodystrophy) and vascular disease (accelerated arteriosclerosis) are two typical entities contributing to this excess morbidity and mortality. Vitamin K and vitamin K-dependent-proteins play pivotal roles in the physiology of mineralization and in preventing ectopic calcification: two of these vitamin K-dependent-proteins are osteocalcin (regulating bone mineralization) and matrix-Gla protein (MGP, local calcification inhibitor in the vessel wall). Vitamin K deficiency impairs the physiological function of osteocalcin and MGP and, therefore, presumably contributes to bone demineralisation and vascular calcification (the so-called calcification paradox). In this context, the usage of vitamin K antagonists for long-term oral anticoagulation therapy might be risky especially in CKD patients exhibiting a high background level of vascular calcification. We present a summary of data describing the potential role of vitamin K deficiency and supplementation in bone and vascular disease in patients with CKD or ESRD.

Topics: Blood Coagulation Factors; Calcinosis; Calcium-Binding Proteins; Cardiovascular Diseases; Extracellular Matrix Proteins; Humans; Kidney Failure, Chronic; Matrix Gla Protein; Vitamin K

It has been hypothesized that insufficient intake of vitamin K may increase soft-tissue calcification owing to impaired gamma-carboxylation of the vitamin K-dependent protein matrix gamma-carboxyglutamic acid. The evidence to support this putative role of vitamin K intake in atherosclerosis is reviewed.. In animal models, multiple forms of vitamin K have been shown to reverse the arterial calcification created by vitamin K antagonists. The human data, however, are less consistent. Phylloquinone, the primary dietary form, has not been associated consistently with the risk of cardiovascular diseases. High menaquinone intake may be associated with lower risk of coronary heart disease mortality, but this needs to be confirmed.. The role of vitamin K in calcification remains controversial. Although biologically plausible, results from the human studies have not consistently supported this hypothesis.

Topics: 1-Carboxyglutamic Acid; Atherosclerosis; Calcinosis; Diet; Humans; Mutation; Vitamin K

Vitamin K-dependent proteins (VKDPs) require carboxylation to become biologically active. Although the coagulant factors are the most well-known VKDPs, there are many others with important physiologic roles. Matrix Gla Protein (MGP) and Growth Arrest Specific Gene 6 (Gas-6) are two particularly important VKDPs, and their roles in vascular biology are just beginning to be understood. Both function to protect the vasculature; MGP prevents vascular calcification and Gas-6 affects vascular smooth muscle cell apoptosis and movement. Unlike the coagulant factors, which undergo hepatic carboxylation, MGP and Gas-6 are carboxylated within the vasculature. This peripheral carboxylation process is distinct from hepatic carboxylation, yet both are inhibited by warfarin administration. Warfarin prevents the activation of MGP and Gas-6, and in animals, induces vascular calcification. The relationship of warfarin to vascular calcification in humans is not fully known, yet observational data suggest an association. Given the high risk of vascular calcification in those patients with chronic kidney disease, the importance of understanding warfarin's effect on VKDPs is paramount. Furthermore, recognizing the importance of VKDPs in vascular biology will stimulate new areas of research and offer potential therapeutic interventions.

Topics: Animals; Anticoagulants; Blood Vessels; Calcinosis; Calcium-Binding Proteins; Extracellular Matrix Proteins; Humans; Intercellular Signaling Peptides and Proteins; Kidney Failure, Chronic; Matrix Gla Protein; Protein Processing, Post-Translational; Risk Assessment; Risk Factors; Vascular Diseases; Vitamin K; Warfarin

Vascular calcification is highly prevalent and correlated with high rates of cardiovascular mortality in chronic kidney disease patients. Recent evidence suggests that mineral, hormonal, and metabolic imbalances that promote phenotype change in vascular cells as well as deficiencies in specific mineralization inhibitory pathways may be important contributory factors for vascular calcification in these patients. This article reviews current mechanisms proposed for the regulation of vascular calcification and data supporting their potential contribution to this process in chronic kidney disease.

Topics: alpha-2-HS-Glycoprotein; Animals; Antifibrinolytic Agents; Blood Proteins; Bone Density Conservation Agents; Bone Morphogenetic Proteins; Calcinosis; Calcium-Binding Proteins; Chronic Disease; Extracellular Matrix Proteins; Humans; Kidney Diseases; Kidney Failure, Chronic; Matrix Gla Protein; Mice; Parathyroid Hormone; Phosphates; Rats; Vascular Diseases; Vitamin D; Vitamin K

Topics: Animals; Anticoagulants; Calcinosis; Chronic Disease; Humans; Renal Dialysis; Renal Insufficiency; Vascular Diseases; Vitamin K; Vitamin K Deficiency; Warfarin

Cardiovascular disease is the leading cause of morbidity and mortality in the western world and atherosclerosis is the major common underlying disease. The pathogenesis of atherosclerosis involves local vascular injury, inflammation and oxidative stress as well as vascular calcification. Vascular calcification has long been regarded as a degenerative process leading to mineral deposition in the vascular wall characteristic for late stages of atherosclerosis. However, recent studies identified vascular calcification in early stages of atherosclerosis and its occurrence has been linked to clinical events in patients with cardiovascular disease. Its degree correlates with local vascular inflammation and with the overall impact and the progression of atherosclerosis. Over the last decade, diverse and highly regulated molecular signaling cascades controlling vascular calcification have been described. Local and circulating molecules such as osteopontin, osteoprogerin, leptin and matrix Gla protein were identified as critical regulators of vascular calcification. We here review the current knowledge on molecular pathways of vascular calcification and their relevance for the progression of cardiovascular disease.

Topics: Calcinosis; Coronary Artery Disease; Humans; Leptin; Proteins; Vitamin K

Topics: Animals; Arteries; Atherosclerosis; Biomechanical Phenomena; Calcinosis; Calcium-Binding Proteins; Coronary Disease; Extracellular Matrix Proteins; Humans; Matrix Gla Protein; Mice; Mixed Function Oxygenases; Rupture; Vitamin K; Vitamin K Epoxide Reductases

Arteriosclerosis, characterized by remodeling and stiffening of large elastic arteries is the most significant manifestation of vascular aging. The increased stiffening is believed to originate from a gradual mechanical senescence of the elastic network, alterations in cross-linking of extracellular matrix components, fibrosis and calcification of elastic fibers (medial elastocalcinosis). The stiffening of large arteries reduces their capacitance and accelerates pulse wave velocity, thus contributing to a widening of pulse pressure and to the increased prevalence of isolated systolic hypertension with age. Current antihypertensive drugs were mainly designed to reduce peripheral resistance and are not adequate to alter the pathological process of vascular stiffening or even to selectively reduce systolic blood pressure in isolated systolic hypertension. This review puts forward the concept that elastocalcinosis is a valuable therapeutic target and presents evidence that this process can be prevented and reversed pharmacologically.

Topics: Aged; Aging; Antihypertensive Agents; Arteries; Arteriosclerosis; Calcinosis; Humans; Hypertension; Muscle, Smooth, Vascular; Osteoporosis; Systole; Vitamin K; Warfarin

Vitamin K has several biological effects and dietary intake seems to be more important than previously believed because of low bioavailability of the vitamins from the colon.. Data from the literature were identified on PubMed, and data from NORKOST II (a dietary study from 1997 based on a nation-wide sample of respondents) were used to calculate dietary intake of vitamin K.. The dietary intake of vitamin K in Norway seems to be < 50% of what is recommended. The stores of vitamin K are small and T/2 in the body is approximately 1-1.5 day. Vitamin K executes its effects by carboxylation of proteins and as ligand (vitamin K2) for a nuclear transcription factor. Biological effects beyond coagulation include bone formation, neural functioning and blood vessel calcification. Anticoagulation with warfarin inhibits vitamin K-dependent reactions and may have detrimental effects on bone formation.. It is possible that the high incidence of osteoporosis in Norway may be due to the low dietary intake of vitamin K, hence it is suggested that the intake of vitamin K should be increased and vitamin K antagonists be replaced with specific thrombin inhibitors. New technology allows measurements of plasma concentration of vitamin K in relation to malabsorption, insufficient diet, and osteoporosis.

Topics: Adult; Blood Coagulation; Bone Density; Calcinosis; Child; Female; Food Analysis; Humans; Male; Nerve Degeneration; Norway; Nutritional Requirements; Osteoporosis; Vitamin K

Vitamin K is well known for its role in the synthesis of a number of blood coagulation factors. During recent years vitamin K-dependent proteins were discovered to be of vital importance for bone and vascular health. Recommendations for dietary vitamin K intake have been made on the basis of the hepatic requirements for the synthesis of blood coagulation factors. Accumulating evidence suggests that the requirements for other functions than blood coagulation may be higher. This paper is the result of a closed workshop (Paris, November 2002) in which a number of European vitamin K experts reviewed the available data and formulated their standpoint with respect to recommended dietary vitamin K intake and the use of vitamin K-containing supplements.

Topics: Antifibrinolytic Agents; Arteriosclerosis; Bone and Bones; Calcinosis; Dietary Supplements; Fractures, Bone; Humans; Nutritional Requirements; Osteocalcin; Osteoporosis; Safety; Vitamin K; Vitamin K Deficiency

Topics: Animals; Arteries; Calcification, Physiologic; Calcinosis; Calcium-Binding Proteins; Cartilage; Extracellular Matrix Proteins; Humans; Matrix Gla Protein; Nutritional Requirements; Organ Specificity; Osteogenesis; Vascular Diseases; Vitamin K

Among the proteins known or suspected to be involved in bone and vascular biology are several members of the vitamin K-dependent or Gla protein family. This review focuses on the role of two of these: osteocalcin and matrix Gla protein. Osteocalcin metabolism has been implicated in the pathogenesis of osteoporosis through an unknown mechanism that may be linked to suboptimal vitamin K status resulting in its undercarboxylation and presumed dysfunction. Recent studies that have investigated this hypothesis are discussed, as are recent promising clinical studies of vitamin K supplementation in osteoporosis. A recently delineated function of matrix Gla protein is as a powerful inhibitor of calcification of arteries and cartilage. In the period covered by this review there have been several landmark studies using cell systems, whole animals and genetic techniques that have consolidated and extended our knowledge of the role of matrix Gla protein in the prevention of ectopic calcification.

Topics: Bone and Bones; Calcinosis; Humans; Osteocalcin; Osteoporosis; Vascular Diseases; Vitamin K

Gamma-carboxyglutamic acid is an amino acid with a dicarboxylic acid side chain. This amino acid, with unique metal binding properties, confers metal binding character to the proteins into which it is incorporated. This amino acid has been discovered in blood coagulation proteins (prothrombin, Factor X, Factor IX, and Factor VII), plasma proteins of unknown function (Protein C, Protein S, and Protein Z), and proteins from calcified tissue (osteocalcin and bone-Gla protein). It has also been observed in renal calculi, atherosclerotic plaque, and the egg chorioallantoic membrane, among other tissues. Gamma-carboxyglutamic acid is synthesized by the post-translational modification of glutamic acid residues. This reaction, catalyzed by a hepatic carboxylase, requires reduced vitamin K, oxygen, and carbon dioxide. The function of gamma-carboxyglutamic acid is uncertain. In prothrombin gamma-carboxyglutamic acid residues bound to metal ions participate as an intramolecular non-covalent bridge to maintain protein conformation. Additionally, these amino acids participate in the calcium-dependent molecular assembly of proteins on membrane surfaces through intermolecular bridges involving gamma-carboxyglutamic acid and metal ions.

Topics: 1-Carboxyglutamic Acid; Animals; Arteriosclerosis; Binding Sites; Blood Proteins; Calcification, Physiologic; Calcinosis; Calcium; Calcium-Binding Proteins; Chemical Phenomena; Chemistry; Factor IX; Factor VII; Factor X; Glutamates; Glycoproteins; Humans; Metals; Osteocalcin; Protein C; Protein S; Proteins; Prothrombin; Urinary Calculi; Vitamin K

Topics: Aged; Aortic Valve; Aortic Valve Stenosis; Calcinosis; Humans; Male; Middle Aged; Models, Cardiovascular; Proof of Concept Study; Prospective Studies; Vitamin K

Coronary artery calcification (CAC) is an independent predictor of cardiovascular disease. A preventive role for vitamin K in CAC progression has been proposed on the basis of the properties of matrix Gla protein (MGP) as a vitamin K-dependent calcification inhibitor.. The objective was to determine the effect of phylloquinone (vitamin K1) supplementation on CAC progression in older men and women.. CAC was measured at baseline and after 3 y of follow-up in 388 healthy men and postmenopausal women; 200 received a multivitamin with 500 microg phylloquinone/d (treatment), and 188 received a multivitamin alone (control).. In an intention-to-treat analysis, there was no difference in CAC progression between the phylloquinone group and the control group; the mean (+/-SEM) changes in Agatston scores were 27 +/- 6 and 37 +/- 7, respectively. In a subgroup analysis of participants who were > or =85% adherent to supplementation (n = 367), there was less CAC progression in the phylloquinone group than in the control group (P = 0.03). Of those with preexisting CAC (Agatston score > 10), those who received phylloquinone supplements had 6% less progression than did those who received the multivitamin alone (P = 0.04). Phylloquinone-associated decreases in CAC progression were independent of changes in serum MGP. MGP carboxylation status was not determined.. Phylloquinone supplementation slows the progression of CAC in healthy older adults with preexisting CAC, independent of its effect on total MGP concentrations. Because our data are hypothesis-generating, further studies are warranted to clarify this mechanism. This trial was registered at clinicaltrials.gov as NCT00183001.

Topics: Aged; C-Reactive Protein; Calcinosis; Calcium; Calcium-Binding Proteins; Coronary Angiography; Coronary Vessels; Dietary Supplements; Double-Blind Method; Extracellular Matrix Proteins; Female; Humans; Interleukin-6; Male; Matrix Gla Protein; Middle Aged; Osteoprotegerin; Postmenopause; Vitamin K; Vitamins

Chronic inflammation is a major driver of chronic inflammatory diseases (CIDs), with a tremendous impact worldwide. Besides its function as a pathological calcification inhibitor, vitamin K-dependent protein Gla-rich protein (GRP) was shown to act as an anti-inflammatory agent independently of its gamma-carboxylation status. Although GRP's therapeutic potential has been highlighted, its low solubility at physiological pH still constitutes a major challenge for its biomedical application. In this work, we produced fluorescein-labeled chitosan-tripolyphosphate nanoparticles containing non-carboxylated GRP (ucGRP) (FCNG) via ionotropic gelation, increasing its bioavailability, stability, and anti-inflammatory potential. The results indicate the nanosized nature of FCNG with PDI and a zeta potential suitable for biomedical applications. FCNG's anti-inflammatory activity was studied in macrophage-differentiated THP1 cells, and in primary vascular smooth muscle cells and chondrocytes, inflamed with LPS, TNFα and IL-1β, respectively. In all these in vitro human cell systems, FCNG treatments resulted in increased intra and extracellular GRP levels, and decreased pro-inflammatory responses of target cells, by decreasing pro-inflammatory cytokines and inflammation mediators. These results suggest the retained anti-inflammatory bioactivity of ucGRP in FCNG, strengthening the potential use of ucGRP as an anti-inflammatory agent with a wide spectrum of application, and opening up perspectives for its therapeutic application in CIDs.

Topics: Calcinosis; Chondrocytes; Humans; Inflammation; Vitamin K

Menaquinone (MK)-7 is a vitamin K2 analog that functions as a cofactor of γ-glutamyl carboxylase involved in the activation of vitamin K (VK)-dependent proteins. The present study aimed to evaluate the effect of MK-7 on memory and cognitive function in aged C57BL/6 mice. Eighteen-month-old mice were raised for a further 4 months, fed on a standard or calcium-rich diet (3 % [w/w]), and were orally given MK-7 (40 and 400 μg/day/mouse) five times per week during the same period. The Morris water maze (MWM) test was performed at 19 and 22 months. The aged mice showed noticeable memory declines in the MWM test at all time points compared with 6-week-old mice, and this memory loss was significantly restored by the daily administration of high-dose MK-7 for 4 months. MK-7 administration also improved micro-computed tomography-based cerebrovascular calcification and aging-associated declines in growth arrest-specific 6, total and carboxylated matrix Gla proteins, and ganglioside levels in the brain of aged mice. It serologically reduced phosphorous levels in the blood, but not the urea, cholesterol, and calcium. Taken together, the long-term administration of MK-7 significantly improved age-related memory and cognitive impairments, possibly through inhibition of cerebrovascular calcification in aged mice, indicating that it can be used to develop new drugs for improving memory and cognitive function in older adults.

Topics: Animals; Calcinosis; Calcium; Cholesterol; Gangliosides; Memory Disorders; Mice; Mice, Inbred C57BL; Urea; Vitamin K; Vitamin K 2; X-Ray Microtomography

Circulating uncarboxylated matrix Gla protein (ucMGP) is possibly related to coronary arterial calcification (CAC) in cardiovascular disease (CVD) patients.. We aimed to evaluate the relationships between circulating ucMGP, CVD pathology and CAC and its interplay with CVD risk factors.. ucMGP was measured in 99 CVD-patients. CAC score was determined by multislice computed tomography. Circulating ucMGP, uncarboxylated (ucOC) and carboxylated osteocalcin (cOC) were assayed by ELISA kits. Vitamin-K status was evaluated by ucOC/cOC ratio.. A tendency for decreased ucMGP was observed for CAC. Circulating ucMGP may reflect certain stages of CVD and CAC. Future studies are needed to clarify its role as potential biomarker.

Topics: Anticoagulants; Atrial Fibrillation; Biomarkers; Calcinosis; Calcium-Binding Proteins; Extracellular Matrix Proteins; Heart Failure; Humans; Matrix Gla Protein; Osteocalcin; Stroke Volume; Vitamin K; Vitamins

The use of vitamin K antagonists (VKA) is associated with the onset of vascular and soft-tissue calcifications. Whether there are more intracranial calcifications under VKA remains unclear. The objective of this study was to determine whether the regular use of VKA in older adults was associated with an increased burden of intracranial calcifications compared with the use of direct oral anticoagulant (DOA).. Nineteen patients aged 70 years or more using VKA for more than 3 months and 19 controls (matched for age, gender and indication for anticoagulation) using DOA for more than 3 months were consecutively included in this study.. The burden of intracranial calcifications was graded by an experienced neuroradiologist from 0 (no burden) to 3 (high burden) according to the quantity, size, intensity and confluence of calcifications on computed tomography scan of the brain. Age, gender, frontal assessment battery (FAB) score, hypertension, dyslipidaemia, carotid artery stenosis, kidney failure and indication for anticoagulation were investigated as potential confounders.. The 19 patients using VKA (median[IQR], 84years[7]; 10females) exhibited a greater burden of falcian calcifications than the 19 controls using DOA (respectively, 2[1] versus 1[2], P = 0.025). Overall, we found that using VKA was directly associated with the global burden of intracranial calcifications (β = 1.54, P = 0.049). No correlation was found with calcifications in sites other than the falx cerebri.. The use of VKA was associated with a greater burden of intracranial calcifications compared with the use of DOA, specifically in the falx cerebri. This finding may explain part of the neurocognitive morbidity met with VKA.

Topics: Administration, Oral; Aged; Aged, 80 and over; Anticoagulants; Brain Diseases; Calcinosis; Dura Mater; Female; France; Humans; Male; Tomography, X-Ray Computed; Vitamin K

Topics: Anticoagulants; Calcinosis; Humans; Vitamin K; Warfarin

Topics: Aortic Valve; Aortic Valve Stenosis; Calcinosis; Humans; Vitamin K

Vitamin K antagonists (VKA) remain the most frequently prescribed oral anticoagulants worldwide despite the introduction of non-vitamin K antagonist oral anticoagulants (NOAC). VKA interfere with the regeneration of Vitamin K1 and K2, essential to the activation of coagulation factors and activation of matrix-Gla protein, a strong inhibitor of arterial calcifications. This study aimed to clarify whether VKA treatment was associated with the extent of coronary artery calcification (CAC) in a population with no prior cardiovascular disease (CVD).. We collected data on cardiovascular risk factors and CAC scores from cardiac CT scans performed as part of clinical examinations (n = 9,672) or research studies (n = 14,166) in the period 2007-2017. Data on use of anticoagulation were obtained from the Danish National Health Service Prescription Database. The association between duration of anticoagulation and categorized CAC score (0, 1-99, 100-399, ≥400) was investigated by ordered logistic regression adjusting for covariates.. The final study population consisted of 17,254 participants with no prior CVD, of whom 1,748 and 1,144 had been treated with VKA or NOAC, respectively. A longer duration of VKA treatment was associated with higher CAC categories. For each year of VKA treatment, the odds of being in a higher CAC category increased (odds ratio (OR) = 1.032, 95%CI 1.009-1.057). In contrast, NOAC treatment duration was not associated with CAC category (OR = 1.002, 95%CI 0.935-1.074). There was no significant interaction between VKA treatment duration and age on CAC category.. Adjusted for cardiovascular risk factors, VKA treatment-contrary to NOAC-was associated to higher CAC category.

Topics: Aged; Anticoagulants; Calcinosis; Coronary Artery Disease; Female; Humans; Male; Middle Aged; Risk Factors; Vitamin K

Pseudoxanthoma elasticum (PXE), caused by ABCC6/MRP6 mutation, is a heritable multisystem disorder in humans. The progressive clinical manifestations of PXE are accompanied by ectopic mineralization in various connective tissues. However, the pathomechanisms underlying the PXE multisystem disorder remains obscure, and effective treatment is currently available. In this study, we generated zebrafish

Topics: Animals; ATP-Binding Cassette Transporters; Calcinosis; Eye; Fibrosis; Genetic Predisposition to Disease; Mutation; Myocardium; Vitamin K; Zebrafish; Zebrafish Proteins

Matrix Gla protein (MGP) is a natural inhibitor of tissue calcification. In a previous study, we observed the positive association between abnormal concentrations of uncarboxylated MGP species and increased mortality risk in stable vascular patients. We explore whether co-incidence of abnormal status of uncarboxylated MPG and heart failure (HF) affects the mortality risk.. We examined 799 patients (mean age 65.1 years) with stable vascular disease and followed them in a prospective study. Both, desphospho-uncarboxylated and total uncarboxylated MGP (dp-ucMGP or t-ucMGP) were quantified by pre-commercial ELISA assays.. Elevated (>100 ng/L) circulating brain natriuretic peptide (BNP) and abnormal status of plasma uncarboxylated MGP species (i.e.: dp-ucMGP ≥ 977 pmol/L or t-ucMGP ≤ 2825 nmol/L) were all identified as robust predictors of all-cause 5-year mortality. However, their co-incidence represented a substantial additional risk. We observed the highest mortality risk in patients with elevated BNP plus high dp-ucMGP compared to those with normal BNP plus low dp-ucMGP; fully adjusted HRR's were 4.86 (3.15-7.49). Likewise, the risk was increased when compared with patients with elevated BNP plus low dp-ucMGP; HRR 2.57 (1.60-4.10). Similar result we observed when co-incidence of elevated BNP and low t-ucMGP was analyzed [corresponding HRR's were 4.16 (2.62-6.61) and 1.96 (1.24-3.12)].. The concomitant abnormality of uncarboxylated MGP and mild elevation of BNP leads in chronic patients with vascular disease to about two-fold increase of the relative mortality risk. We hypothesize that abnormal homeostasis of MGP is involved in the pathophysiology of HF.

Topics: Aged; Biomarkers; Calcinosis; Calcium-Binding Proteins; Czech Republic; Extracellular Matrix Proteins; Female; Follow-Up Studies; Heart Failure; Humans; Male; Matrix Gla Protein; Prospective Studies; Risk Assessment; Risk Factors; Survival Rate; Vascular Diseases; Vitamin K

Essentials Vitamin K plays a role in coagulation, and deficiency may promote coronary artery calcification. The role of vitamin K1 in heart disease was assessed using Mendelian randomization in Caucasians. Genetically higher vitamin K1 was associated with a higher risk of ischemic heart disease. Further research elucidating the role of vitamin K1 in ischemic heart disease could be useful.. Background Vitamin K1 is a nutrient in green leafy vegetables; deficiency may promote coronary artery calcification. Warfarin, an anticoagulant used in secondary prevention of thrombotic events, is a vitamin K antagonist. Thrombotic and coronary events may share risk factors. Objectives To clarify the role of vitamin K1 in ischemic heart disease, the risk of coronary artery disease/myocardial infarction (CAD/MI) was assessed according to genetically determined vitamin K1 levels. Given vitamin K1 is fat soluble, associations with lipids were similarly assessed to assess pleotropic effects via lipids. Methods Separate sample instrumental variable analysis with genetic instruments (Mendelian randomization) was used to obtain an unconfounded estimate of the association of vitamin K1 (based on rs2108622 [CYP4F2], rs4645543 [KCNK9] and rs2192574 [CTNNA2] from a genome-wide association study) with CAD/MI using CARDIoGRAMplusC4D (cases = 64 374; controls = 130 681) and with lipids using Global Lipids Genetics Consortium Results (n = 196 475). Results Vitamin K1 single nucleotide polymorphisms were positively associated with CAD/MI (odds ratio [OR], 1.17 per unit [nmol L(-1) ] of natural log-transformed genetically predicted vitamin K1 ; 95% confidence interval [CI], 1.08-1.26), but not with inverse normal transformed low-density lipoprotein cholesterol (-0.0003; 95% CI, -0.03 to 0.03), high-density lipoprotein cholesterol (0.02; 95% CI, -0.01 to 0.05) or triglycerides (-0.01; 95% CI, -0.04 to 0.02). Considering only rs2108622, which is functionally relevant to vitamin K1 , the association for CAD/MI was stronger (OR, 1.21; 95% CI, 1.08-1.36). Conclusions Vitamin K may cause CAD/MI; whether vitamin K or other determinants of coagulation could be relevant to primary prevention might be worth considering.

Topics: Calcinosis; Case-Control Studies; Cholesterol, LDL; Coronary Artery Disease; Coronary Vessels; Diet; Female; Genome-Wide Association Study; Humans; Linkage Disequilibrium; Male; Mendelian Randomization Analysis; Middle Aged; Myocardial Infarction; Myocardial Ischemia; Polymorphism, Single Nucleotide; Risk Factors; Triglycerides; Vitamin K; Warfarin; White People

A high dietary intake of vitamin K1 (phylloquinone) and vitamin K2 (menaquinones) is thought to decrease cardiovascular disease risk by reducing vascular calcification. The objective of this study is to explore if there is a relationship between phylloquinone and menaquinones intake and risk of PAD.. We investigated the association between intake of phylloquinone and menaquinones with PAD in a prospective cohort with 36,629 participants. Occurrence of PAD was obtained by linkage to national registries. Baseline intake of phylloquinone and menaquinones was estimated using a validated food-frequency questionnaire. Multivariate Cox regression was used to estimate adjusted hazard ratio's for the association.. During 12.1 years (standard deviation 2.1 years) of follow-up, 489 incident cases of PAD were documented. Menaquinones intake was associated with a reduced risk of PAD with a hazard ratio (HR) of 0.71, 95% CI; 0.53-0.95 for the highest versus lowest quartile. A stronger association was observed (p interaction 0.0001) in participants with hypertension (HRQ4 versus Q1 0.59; 95% CI 0.39-0.87) or diabetes (HRQ4 versus Q1 0.56; 95% CI 0.18-1.91), though confidence intervals were wide in the small (n = 530) diabetes stratum. Phylloquinone intake was not associated with PAD risk.. High intake of menaquinones was associated with a reduced risk of PAD, at least in hypertensive participants. High intake of phylloquinone was not associated with a reduced risk of PAD.

Topics: Adult; Aged; Calcinosis; Diet; Female; Follow-Up Studies; Humans; Male; Middle Aged; Multivariate Analysis; Peripheral Arterial Disease; Proportional Hazards Models; Prospective Studies; Registries; Risk Factors; Surveys and Questionnaires; Vitamin K; Vitamin K 1; Vitamin K 2; Young Adult

Vitamin K-dependent protein (VKDP) activity may have a role in preventing cardiovascular calcification, but has not previously been studied in large, generally healthy populations.. Using an elevated ankle-brachial index (ABI) as a measure of medial vascular calcification, we performed a case-cohort analysis within the Multi-Ethnic Study of Atherosclerosis, measuring Des-gamma-carboxy prothrombin (DCP) to estimate VKDP activity. In secondary analyses of the weighted subcohort, we examined the cross-sectional associations between DCP and prevalent vascular calcification of the coronary vessels, aortic and mitral valves, and aortic wall, and with vascular stiffness.. In adjusted analysis, cases (n = 104) had 0.21 ng/ml (-0.94-0.52) lower DCP concentrations than the subcohort (n = 613). Furthermore, amongst the 717 participants in the weighted cohort, VKDP activity was not associated with coronary artery, mitral valve, aortic valve or aortic wall calcification, nor was it associated with vascular stiffness.. Our negative results do not support a role of circulating VKDP activity in cardiovascular calcification in community-dwelling adults.

Topics: Aged; Aged, 80 and over; Ankle Brachial Index; Aorta; Aortic Valve; Atherosclerosis; Biomarkers; Calcinosis; Calcium-Binding Proteins; Cohort Studies; Coronary Vessels; Cross-Sectional Studies; Ethnicity; Female; Humans; Male; Middle Aged; Mitral Valve; Protein Precursors; Prothrombin; Vascular Calcification; Vascular Stiffness; Vitamin K

The mineralisation disorder pseudoxanthoma elasticum (PXE) is associated with mutations in the transporter protein ABCC6. Patients with PXE suffer from calcified lesions in the skin, eyes and vasculature, and PXE is related to a more severe vascular calcification syndrome called generalised arterial calcification of infancy (GACI). Mutations in ABCC6 are linked to reduced levels of circulating vitamin K. Here, we describe a mutation in the zebrafish (Danio rerio) orthologue abcc6a, which results in extensive hypermineralisation of the axial skeleton. Administration of vitamin K to embryos was sufficient to restore normal levels of mineralisation. Vitamin K also reduced ectopic mineralisation in a zebrafish model of GACI, and warfarin exacerbated the mineralisation phenotype in both mutant lines. These data suggest that vitamin K could be a beneficial treatment for human patients with PXE or GACI. Additionally, we found that abcc6a is strongly expressed at the site of mineralisation rather than the liver, as it is in mammals, which has significant implications for our understanding of the function of ABCC6.

Topics: Animals; Anthraquinones; ATP-Binding Cassette Transporters; Calcinosis; Chromosomes, Artificial, Bacterial; DNA Primers; In Situ Hybridization; Mutation; Pseudoxanthoma Elasticum; Transgenes; Vascular Calcification; Vitamin K; Warfarin; Zebrafish; Zebrafish Proteins

Warfarin, a widely used anticoagulant, is a vitamin K antagonist impairing the activity of vitamin K-dependent Bone Gla Protein (BGP or Osteocalcin) and Matrix Gla Protein (MGP). Because dabigatran, a new anticoagulant, has no effect on vitamin K metabolism, the aim of this study was to compare the impact of warfarin and dabigatran administration on bone structure and vascular calcification.. Rats with normal renal function received for 6 weeks warfarin, dabigatran or placebo. Bone was evaluated immuno-histochemically and hystomorphometrically after double labelling with declomycin and calcein. Aorta and iliac arteries were examined histologically.. Histomorphometric analysis of femur and vertebrae showed significantly decreased bone volume and increased trabecular separation in rats treated with warfarin. Vertebra analysis showed that the trabecular number was higher in dabigatran treated rats. Osteoblast activity and resorption parameters were similar among groups, except for maximum erosion depth, which was higher in warfarin treated rats, suggesting a higher osteoclastic activity. Therefore, warfarin treatment was also associated with higher bone formation rate/bone surface and activation frequency. Warfarin treatment may cause an increased bone turnover characterized by increased remodelling cycles, with stronger osteoclast activity compared to the other groups. There were no differences among experimental groups in calcium deposition either in aortic or iliac arteries.. These findings suggest for the first time that dabigatran has a better bone safety profile than warfarin, as warfarin treatment affects bone by reducing trabecular size and structure, increasing turnover and reducing mineralization. These differences could potentially result in a lower incidence of fractures in dabigatran treated patients.

Topics: Animals; Anticoagulants; Antithrombins; Aorta; Bone and Bones; Bone Diseases, Metabolic; Bone Remodeling; Calcinosis; Dabigatran; Female; Fractures, Spontaneous; Iliac Artery; Kidney; Minerals; Osteoblasts; Osteoclasts; Random Allocation; Rats; Rats, Sprague-Dawley; Vascular Diseases; Vitamin K; Warfarin

In chronic kidney disease, vitamin K-dependent proteins, including the calcification inhibitor matrix Gla protein, are largely uncarboxylated indicating that functional vitamin K deficiency may contribute to uremic vascular calcification. Since the effects of uremia on the vitamin K cycle are unknown, we investigated the influence of uremia and vitamin K supplementation on the activity of the vitamin K cycle and extraosseous calcification. Uremia was induced in rats by an adenine-supplemented diet and vitamin K1 or K2 was administered over 4 and 7 weeks. After 4 weeks of adenine diet, the activity of the vitamin K cycle enzyme γ-carboxylase but not the activities of DT-diaphorase or vitamin K epoxide reductase were reduced. Serum levels of undercarboxylated matrix Gla protein increased, indicating functional vitamin K deficiency. There was no light microscopy-detectable calcification at this stage but chemically determined aortic and renal calcium content was increased. Vitamin K treatment reduced aortic and renal calcium content after 4 weeks. Seven weeks of uremia induced overt calcification in the aorta, heart, and kidneys; however, addition of vitamin K restored intrarenal γ-carboxylase activity and overstimulated it in the liver along with reducing heart and kidney calcification. Thus, uremic vitamin K deficiency may partially result from a reduction of the γ-carboxylase activity which possibly contributes to calcification. Pharmacological vitamin K supplementation restored the vitamin K cycle and slowed development of soft tissue calcification in experimental uremia.

Topics: Animals; Aorta; Calcinosis; Calcium-Binding Proteins; Carbon-Carbon Ligases; Extracellular Matrix Proteins; Kidney; Liver; Male; Matrix Gla Protein; NAD(P)H Dehydrogenase (Quinone); Rats; Rats, Wistar; Uremia; Vitamin K; Vitamin K 1; Vitamin K 2; Vitamin K Deficiency

High vitamin K intake is associated with a reduced risk of coronary heart disease (CHD). This is thought to be mediated by increased activation of the vitamin K-dependent matrix γ-carboxyglutamate protein (MGP). Desphospho-uncarboxylated MGP (dp-ucMGP) is associated with both vitamin K status and vascular calcification. However, the association of dp-ucMGP with CHD and stroke in the general population has not been investigated to date.. To investigate the association of dp-ucMGP with incident CHD or stroke.. A prospective case-cohort study with a representative baseline sample of 1406 participants and 1154 and 380 incident cases of CHD and stroke, respectively, was nested within the EPIC-NL study. Circulating dp-ucMGP levels were measured with ELISA in baseline plasma samples. The incidence rates of fatal and non-fatal CHD and stroke were obtained by linkage to national registers. Cox proportional hazard models were used to calculate hazard ratios (HRs) per standard deviation (SD) and per quartile of circulating dp-ucMGP levels.. The average follow-up was 11.5 years. Levels of dp-ucMGP were not associated with CHD risk, with an HR per SD of 1.00 (95% confidence interval [CI] 0.93-1.07) and an HRQ4 vs. Q1 of 0.94 (95% CI 0.79-1.13) after adjustment for cardiovascular risk factors. There was no association of dp-ucMGP stroke risk (HRSD  0.98, 95% CI 0.90-1.08; and HRQ4 vs. Q1  1.09, 95% CI 0.78-1.51). This study could not confirm that high dp-ucMGP levels, reflecting poor vitamin K status, are associated with increased CHD or stroke risk in the general population.

Topics: Adult; Aged; Calcinosis; Calcium-Binding Proteins; Case-Control Studies; Coronary Disease; Enzyme-Linked Immunosorbent Assay; Extracellular Matrix Proteins; Female; Follow-Up Studies; Humans; Incidence; Male; Matrix Gla Protein; Middle Aged; Proportional Hazards Models; Risk Factors; Stroke; Treatment Outcome; Vitamin K

Gla-rich protein (GRP) was described in sturgeon as a new vitamin-K-dependent protein (VKDP) with a high density of Gla residues and associated with ectopic calcifications in humans. Although VKDPs function has been related with γ-carboxylation, the Gla status of GRP in humans is still unknown. Here, we investigated the expression of recently identified GRP spliced transcripts, the γ-carboxylation status, and its association with ectopic calcifications, in skin basal cell and breast carcinomas. GRP-F1 was identified as the predominant splice variant expressed in healthy and cancer tissues. Patterns of γ-carboxylated GRP (cGRP)/undercarboxylated GRP (ucGRP) accumulation in healthy and cancer tissues were determined by immunohistochemistry, using newly developed conformation-specific antibodies. Both GRP protein forms were found colocalized in healthy tissues, while ucGRP was the predominant form associated with tumor cells. Both cGRP and ucGRP found at sites of microcalcifications were shown to have in vitro calcium mineral-binding capacity. The decreased levels of cGRP and predominance of ucGRP in tumor cells suggest that GRP may represent a new target for the anticancer potential of vitamin K. Also, the direct interaction of cGRP and ucGRP with BCP crystals provides a possible mechanism explaining GRP association with pathological mineralization.

Topics: alpha-Galactosidase; Breast Neoplasms; Calcinosis; Carcinoma, Basal Cell; Female; Humans; Naphthoquinones; Osteocalcin; Skin Neoplasms; Vitamin K

A number of beta-thalassemia (β-thal) patients in the course of the disease exhibit ectopic calcification affecting skin, eyes and the cardiovascular system. Clinical and histopathological features have been described similar to those in pseudoxanthoma elasticum (PXE), although different genes are affected in the two diseases. Cultured dermal fibroblasts from β-thal patients with and without PXE-like clinical manifestations have been compared for parameters of redox balance and for the expression of proteins, which have been already associated with the pathologic mineralisation of soft connective tissues. Even though oxidative stress is a well-known condition of β-thal patients, our results indicate that the occurrence of mineralized elastin is associated with a more pronounced redox disequilibrium, as demonstrated by the intracellular increase of anion superoxide and of oxidized proteins and lipids. Moreover, fibroblasts from β-thal PXE-like patients are characterized by decreased availability of carboxylated matrix Gla protein (MGP), as well as by altered expression of proteins involved in the vitamin K-dependent carboxylation process. Results demonstrate that elastic fibre calcification is promoted when redox balance threshold levels are exceeded and the vitamin K-dependent carboxylation process is affected decreasing the activity of MGP, a well-known inhibitor of ectopic calcification. Furthermore, independently from the primary gene defect, these pathways are similarly involved in fibroblasts from PXE and from β-thal PXE-like patients as well as in other diseases leading to ectopic calcification, thus suggesting that can be used as markers of pathologic mineralisation.

Topics: Adult; Advanced Oxidation Protein Products; beta-Thalassemia; Blotting, Western; Calcinosis; Calcium-Binding Proteins; Carboxylic Acids; Dermis; DNA Methylation; Elastic Tissue; Elastin; Extracellular Matrix Proteins; Female; Fibroblasts; Flow Cytometry; Glutathione Peroxidase; Glutathione Transferase; Humans; Lipid Peroxides; Male; Malondialdehyde; Matrix Gla Protein; Oxidative Stress; Pseudoxanthoma Elasticum; Superoxide Dismutase; Vitamin K

Matrix Gla protein (MGP) is a vitamin K-dependent protein and an inhibitor of vascular calcification. Vitamin K is required for the carboxylation of MGP and can thereby reduce calcification. Circulating MGP species with different conformations have been investigated as markers for coronary artery calcification (CAC). In high-risk populations, high total uncarboxylated MGP (t-ucMGP) was associated with decreased CAC, while high non-phosphorylated uncarboxylated MGP (dp-ucMGP) was associated with a poor vitamin K status. This cross-sectional study investigated the association of MGP species with CAC, vitamin K status among 200 healthy women. Circulating dp-ucMGP, t-ucMGP and, non-phosphorylated carboxylated MGP (dp-cMGP) levels were measured by ELISA techniques and Agatston score by multi-detector computed tomography. The ratio of uncarboxylated to carboxylated osteocalcin was used as proxy of vitamin K status. A borderline significant (P=.06) association between higher circulating dp-ucMGP levels and high CAC was observed (β=0.091, 95% CI-0.01; 0.19). In the entire study population, high t-ucMGP levels tended to be associated (P=.09) with lower CAC (β=-0.36, 95% CI:-0.78; 0.06). This association strengthened amongst women with CAC to a significant relation between high t-ucMGP levels and lower CAC (β=-0.55, 95% CI-1.01;-0.10). Dp-cMGP was not associated with CAC. Low vitamin K-status was associated with high dp-ucMGP concentrations (β=0.138, 95% CI 0.09; 0.19) but not with other MGP species. These results show that dp-ucMGP may serve as a biomarker of vitamin K status. Circulating dp-ucMGP and t-ucMGP may serve as markers for the extent of CAC, but these findings need to be confirmed.

Topics: Calcinosis; Calcium-Binding Proteins; Coronary Vessels; Cross-Sectional Studies; Enzyme-Linked Immunosorbent Assay; Extracellular Matrix Proteins; Female; Humans; Matrix Gla Protein; Reference Values; Vitamin K

Mineralization of elastic fibers in pseudoxanthoma elasticum (PXE) has been associated with low levels of carboxylated matrix gla protein (MGP), most likely as a consequence of reduced vitamin K (vit K) availability. Unexpectedly, vit K supplementation does not exert beneficial effects on soft connective tissue mineralization in the PXE animal model. To understand the effects of vit K supplementation and in the attempt to interfere with pathways leading to the accumulation of calcium and phosphate within PXE-mineralized soft connective tissues, we have conducted in vitro studies on dermal fibroblasts isolated from control subjects and from PXE patients. Cells were cultured in standard conditions and in calcifying medium (CM) in the presence of vit K1 and K2, or levamisole, an alkaline phosphatase (ALP) inhibitor. Control and PXE fibroblasts were characterized by a similar dose-dependent uptake of both vit K1 and vit K2, thus promoting a significant increase of total protein carboxylation in all cell lines. Nevertheless, MGP carboxylation remained much less in PXE fibroblasts. Interestingly, PXE fibroblasts exhibited a significantly higher ALP activity. Consistently, the mineralization process induced in vitro by a long-term culture in CM appeared unaffected by vit K, whereas it was abolished by levamisole.

Topics: Adjuvants, Immunologic; Adult; Alkaline Phosphatase; Antifibrinolytic Agents; Calcification, Physiologic; Calcinosis; Calcium; Calcium-Binding Proteins; Cell Survival; Cells, Cultured; Dermis; Enzyme Activation; Extracellular Matrix Proteins; Female; Fibroblasts; Humans; Levamisole; Matrix Gla Protein; Middle Aged; Phosphates; Pseudoxanthoma Elasticum; Vitamin K

Vitamin K-antagonists (VKA) are treatment of choice and standard care for patients with venous thrombosis and thromboembolic risk. In experimental animal models as well as humans, VKA have been shown to promote medial elastocalcinosis. As vascular calcification is considered an independent risk factor for plaque instability, we here investigated the effect of VKA on coronary calcification in patients and on calcification of atherosclerotic plaques in the ApoE(-/-) model of atherosclerosis.. A total of 266 patients (133 VKA users and 133 gender and Framingham Risk Score matched non-VKA users) underwent 64-slice MDCT to assess the degree of coronary artery disease (CAD). VKA-users developed significantly more calcified coronary plaques as compared to non-VKA users. ApoE(-/-) mice (10 weeks) received a Western type diet (WTD) for 12 weeks, after which mice were fed a WTD supplemented with vitamin K(1) (VK(1), 1.5 mg/g) or vitamin K(1) and warfarin (VK(1)&W; 1.5 mg/g & 3.0 mg/g) for 1 or 4 weeks, after which mice were sacrificed. Warfarin significantly increased frequency and extent of vascular calcification. Also, plaque calcification comprised microcalcification of the intimal layer. Furthermore, warfarin treatment decreased plaque expression of calcification regulatory protein carboxylated matrix Gla-protein, increased apoptosis and, surprisingly outward plaque remodeling, without affecting overall plaque burden.. VKA use is associated with coronary artery plaque calcification in patients with suspected CAD and causes changes in plaque morphology with features of plaque vulnerability in ApoE(-/-) mice. Our findings underscore the need for alternative anticoagulants that do not interfere with the vitamin K cycle.

Topics: Aged; Animals; Apolipoproteins E; Atherosclerosis; Calcinosis; Coronary Artery Disease; Female; Humans; Male; Mice; Mice, Transgenic; Middle Aged; Phenotype; Plaque, Atherosclerotic; Risk; Thromboembolism; Vitamin K; Warfarin

Pseudoxanthoma elasticum (PXE) is a heritable multisystem disorder manifesting with ectopic calcification of peripheral connective tissues, caused by mutations in the ABCC6 gene. Alterations in vitamin K metabolism have been suggested to contribute to the pathomechanisms of the mineralization process. In this study we administered vitamin K or its glutathione conjugate (K3-GSH) into Abcc6 (-/-) mice which recapitulate features of PXE. Oral administration of vitamin K2 in dosages, which vastly exceed the amounts in control diet or the recommended amounts for humans, did not alter the ectopic mineralization in Abcc6 (-/-) mice. Similarly, intravenous administration of K3-GSH did not alter the degree of mineralization. Testing of vitamin K2, K3 and K3-GSH in an in vitro calcification system provided no evidence of mineralization inhibition. Collectively, our data suggest that vitamin K deficiency in the peripheral tissues is not a simple explanation for development of mineral deposits in PXE.

Topics: Animals; ATP-Binding Cassette Transporters; Calcinosis; Cell Line; Disease Models, Animal; Elastic Tissue; Female; Humans; Male; Mice; Mice, Knockout; Multidrug Resistance-Associated Proteins; Mutation; Pseudoxanthoma Elasticum; Vitamin K; Vitamin K Deficiency

 Matrix γ-carboxyglutamate protein (MGP), a vitamin K-dependent protein, is recognized as a potent local inhibitor of vascular calcification. Studying patients with Keutel syndrome (KS), a rare autosomal recessive disorder resulting from MGP mutations, provides an opportunity to investigate the functions of MGP. The purpose of this study was (i) to investigate the phenotype and the underlying MGP mutation of a newly identified KS patient, and (ii) to investigate MGP species and the effect of vitamin K supplements in KS patients..  The phenotype of a newly identified KS patient was characterized with specific attention to signs of vascular calcification. Genetic analysis of the MGP gene was performed. Circulating MGP species were quantified and the effect of vitamin K supplements on MGP carboxylation was studied. Finally, we performed immunohistochemical staining of tissues of the first KS patient originally described focusing on MGP species..  We describe a novel homozygous MGP mutation (c.61+1G>A) in a newly identified KS patient. No signs of arterial calcification were found, in contrast to findings in MGP knockout mice. This patient is the first in whom circulating MGP species have been characterized, showing a high level of phosphorylated MGP and a low level of carboxylated MGP. Contrary to expectations, vitamin K supplements did not improve the circulating carboxylated mgp levels. phosphorylated mgp was also found to be present in the first ks patient originally described..  Investigation of the phenotype and MGP species in the circulation and tissues of KS patients contributes to our understanding of MGP functions and to further elucidation of the difference in arterial phenotype between MGP-deficient mice and humans.

Topics: Abnormalities, Multiple; Arteries; Calcinosis; Calcium-Binding Proteins; Cartilage Diseases; Extracellular Matrix Proteins; Hand Deformities, Congenital; Homozygote; Humans; Matrix Gla Protein; Mutation; Pulmonary Valve Stenosis; Vitamin K

Pseudoxanthoma elasticum (PXE) is a heritable disease characterized by calcified elastic fibers in cutaneous, ocular, and vascular tissues. PXE is caused by mutations in ABCC6, which encodes a protein of the ATP-driven organic anion transporter family. The inability of this transporter to secrete its substrate into the circulation is the likely cause of PXE. Vitamin K plays a role in the regulation of mineralization processes as a co-factor in the carboxylation of calcification inhibitors such as Matrix Gla Protein (MGP). Vitamin K precursor or a conjugated form has been proposed as potential substrate(s) for ABCC6. We investigated whether an enriched diet of vitamin K1 or vitamin K2 (MK4) could stop or slow the disease progression in Abcc6 (-/-) mice. Abcc6 (-/-) mice were placed on a diet of either vitamin K1 or MK4 at 5 or 100 mg/kg at prenatal, 3 weeks or 3 months of age. Disease progression was quantified by measuring the calcium content of one side of the mouse muzzle skin and histological staining for calcium of the opposing side. Raising the vitamin K1 or MK4 content of the diet increased the concentration of circulating MK4 in the serum. However, this increase did not significantly affect the MGP carboxylation status or reduce its abnormal abundance, the total calcium content or the pathologic calcification in the whiskers of the 3 treatment groups compared to controls. Our findings showed that raising the dietary intake of vitamin K1 or MK4 was not beneficial in the treatment of PXE and suggested that the availability of vitamin K may not be a limiting factor in this pathology.

Topics: Animals; ATP-Binding Cassette Transporters; Calcinosis; Dietary Supplements; Disease Models, Animal; Mice; Mice, Knockout; Multidrug Resistance-Associated Proteins; Pseudoxanthoma Elasticum; Treatment Failure; Vitamin K

Soft-tissue mineralization is a tightly regulated process relying on the activity of systemic and tissue-specific inhibitors and promoters of calcium precipitation. Many of these, such as matrix gla protein (MGP) and osteocalcin (OC), need to undergo carboxylation to become active. This post-translational modification is catalyzed by the gammaglutamyl carboxylase GGCX and requires vitamin K (VK) as an essential co-factor. Recently, we described a novel phenotype characterized by aberrant mineralization of the elastic fibers resulting from mutations in GGCX. Because of the resemblance with pseudoxanthoma elasticum (PXE), a prototype disorder of elastic fiber mineralization, it was coined the PXE-like syndrome. As mutations in GGCX negatively affect protein carboxylation, it is likely that inactive inhibitors of calcification contribute to ectopic mineralization in PXE-like syndrome. Because of the remarkable similarities with PXE, we performed a comparative study of various forms of VK-dependent proteins in serum, plasma (using ELISA), and dermal tissues (using immunohistochemistry) of PXE-like and PXE patients using innovative, conformation-specific antibodies. Furthermore, we measured VK serum concentrations (using HPLC) in PXE-like and PXE samples to evaluate the VK status. In PXE-like patients, we noted an accumulation of uncarboxylated Gla proteins, MGP, and OC in plasma, serum, and in the dermis. Serum levels of VK were normal in these patients. In PXE patients, we found similar, although not identical results for the Gla proteins in the circulation and dermal tissue. However, the VK serum concentration in PXE patients was significantly decreased compared with controls. Our findings allow us to conclude that ectopic mineralization in the PXE-like syndrome and in PXE results from a deficient protein carboxylation of VK-dependent inhibitors of calcification. Although in PXE-like patients this is due to mutations in the GGCX gene, a deficiency of the carboxylation co-factor VK is at the basis of the decreased activity of calcification inhibitors in PXE.

Topics: Adult; Aged; Animals; Calcinosis; Calcium-Binding Proteins; Extracellular Matrix Proteins; Humans; Matrix Gla Protein; Mice; Mice, Knockout; Middle Aged; Mixed Function Oxygenases; Mutation; Proteins; Pseudoxanthoma Elasticum; Syndrome; Vitamin K; Vitamin K Deficiency; Vitamin K Epoxide Reductases

Vascular calcification in humans is associated with an increased cardiovascular risk. Carboxylated matrix Gla protein (cMGP) inhibits vascular calcification. Vitamin K is an essential cofactor for the activation of uncarboxylated matrix Gla protein (ucMGP). It has been suggested that patients on long-term treatment with vitamin K antagonists develop aortic valve calcifications because of lower levels of circulating MGP. We therefore hypothesized that arterial calcification and a low vitamin K status are associated with ucMGP. To that aim, we measured arterial calcium scores, the osteocalcin ratio (OCR), as a proxy for vitamin K status, and ucMGP.. In 36 hypertensive patients, we determined the Agatston score with computer tomography scans of the abdominal aorta, carotid and coronary arteries. The total calcium score was calculated as the sum of the separate Z-scores.. The total calcium Z-score was significantly correlated to age (r = 0.683, P < 0.001), smoking (r = 0.372, P = 0.026), total cholesterol (r = 0.353, P = 0.034), LDL cholesterol (r = 0.490, P = 0.003), triglycerides (r = 0.506, P = 0.002), fasting glucose (r = 0.454, P = 0.005), systolic blood pressure (r = 0.363, P = 0.029) and pulse pressure (r = 0.685, P < 0.001). In multivariate regression analyses, OCR and total calcium score were significantly associated with ucMGP.. We found a positive association of total arterial calcium score and a high OCR (reflecting low vitamin K status) with ucMGP serum levels. This warrants further studies to explore the pathophysiological background of this phenomenon.

Topics: Adult; Aged; Aged, 80 and over; Calcinosis; Calcium; Calcium-Binding Proteins; Cardiomyopathies; Extracellular Matrix Proteins; Female; Humans; Hypertension; Male; Matrix Gla Protein; Middle Aged; Osteocalcin; Tomography, X-Ray Computed; Vitamin K

Matrix γ-carboxyglutamate (Gla) protein (MGP) is an important local inhibitor of vascular calcification, which can undergo two post-translational modifications: vitamin K-dependent γ-glutamate carboxylation and serine phosphorylation. While carboxylation is thought to have effects upon binding of calcium-ions, phosphorylation is supposed to affect the cellular release of MGP. Since both modifications can be exerted incompletely, various MGP species can be detected in the circulation. MGP levels were measured with two commercially available competitive and two novel sandwich assays in healthy controls, in patients with rheumatic disease, aortic valve disease, and end-stage renal disease, as well as in volunteers after vitamin K supplementation (VKS) and treatment with vitamin K antagonists (VKA). Major differences were found between the MGP assays, including significantly different behaviour with regard to vascular disease and the response to VKA and VKS. The dual-antibody assay measuring non-phosphorylated, non-carboxylated MGP (dp-ucMGP) was particularly sensitive for these changes and would be suited to assess the vascular vitamin K status. We conclude that the different assays for particular circulating MGP species allows the assessment of various aspects of the MGP system.

Topics: Adult; Aged; Antibodies, Monoclonal; Aortic Valve Insufficiency; Arthritis, Rheumatoid; Biomarkers; Calcinosis; Calcium-Binding Proteins; Chondrocalcinosis; Disease Progression; Enzyme-Linked Immunosorbent Assay; Extracellular Matrix Proteins; Feasibility Studies; Humans; Kidney Failure, Chronic; Matrix Gla Protein; Middle Aged; Prognosis; Protein Processing, Post-Translational; Vitamin K

The role of vitamin K in the synthesis of some coagulation factors is well known. The implication of vitamin K in vascular health was demonstrated in many surveys and studies conducted over the past years on the vitamin K-dependent proteins non-involved in coagulation processes. The vitamin K-dependent matrix Gla protein is a potent inhibitor of the arterial calcification, and may become a non-invasive biochemical marker for vascular calcification. Vitamin K(2) is considered to be more important for vascular system, if compared to vitamin K(1). This paper is reviewing the data from recent literature on the involvement of vitamin K and vitamin K-dependent proteins in cardiovascular health.

Topics: Animals; Blood Coagulation; Calcinosis; Calcium-Binding Proteins; Extracellular Matrix Proteins; Humans; Matrix Gla Protein; Vascular Diseases; Vitamin K

Topics: Administration, Oral; Animals; Anticoagulants; Aortic Valve; Biomarkers; Calcinosis; Calcium-Binding Proteins; Chronic Disease; Down-Regulation; Extracellular Matrix Proteins; Glomerular Filtration Rate; Heart Valve Diseases; Humans; Kidney Diseases; Matrix Gla Protein; Prognosis; Vascular Diseases; Vitamin K

Matrix-Gla Protein (MGP) is a vitamin K-dependent protein acting as a local inhibitor of vascular calcification. Vitamin K-antagonists (oral anticoagulant; OAC) inhibit the activation of MGP by blocking vitamin K-metabolism. The aim of this study was to investigate the effect of long-term OAC treatment on circulating MGP levels in humans and on MGP expression in mice. Additionally, we tested the association between circulating inactive MGP (ucMGP) levels and the presence and severity of AVC in patients with aortic valve disease (AVD). We analysed circulating ucMGP levels in 191 consecutive patients with echocardiographically proven calcific AVD and 35 control subjects. The extent of AVC in the patients was assessed by multislice spiral computed tomography. Circulating ucMGP levels were significantly lower in patients with AVD (348.6 +/- 123.1 nM) compared to the control group (571.6 +/- 153.9 nM, p < 0.001). Testing the effect of coumarin in mice revealed that also the mRNA expression of MGP in the aorta was downregulated. Multifactorial analysis revealed a significant effect of glomerular filtration rate and long-term OAC therapy on circulating ucMGP levels in the patient group. Subsequently, patients on long-term OAC had significantly increased AVC scores. In conclusion, patients with calcific AVD had significantly lower levels of circulating ucMGP as compared to a reference population, free of coronary and valvular calcifications. In addition, our data suggest that OAC treatment may decrease local expression of MGP, resulting in decreased circulating MGP levels and subsequently increased aortic valve calcifications as an adverse side effect.

Topics: Administration, Oral; Adult; Aged; Aged, 80 and over; Animals; Anticoagulants; Aorta; Aortic Valve; Biomarkers; Calcinosis; Calcium-Binding Proteins; Case-Control Studies; Cross-Sectional Studies; Disease Models, Animal; Down-Regulation; Echocardiography; Extracellular Matrix Proteins; Female; Glomerular Filtration Rate; Heart Valve Diseases; Humans; Male; Matrix Gla Protein; Mice; Mice, Inbred DBA; Middle Aged; Osteopontin; Prognosis; Risk Assessment; Risk Factors; RNA, Messenger; Severity of Illness Index; Time Factors; Tomography, Spiral Computed; Vitamin K; Warfarin

Topics: Animals; Anticoagulants; Atrial Fibrillation; Calcinosis; Coumarins; Humans; Mice; Quality-Adjusted Life Years; Renal Dialysis; Vitamin K

Matrix gamma-carboxyglutamic acid protein (MGP), a vitamin K-dependent protein, is involved in regulation of tissue calcification. We previously reported that 9-cis retinoic acid (RA) mitigates 1alpha,25-dihydroxycholecalciferol [1,25(OH)(2)D3]-induced renal calcification in a 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung cancer A/J male mouse model. This raised the question if the mechanism(s) underlying this calcification involves vitamin K. We assessed expression and vitamin K dependent gamma-carboxylation of MGP and vitamin K concentrations [phylloquinone (PK), as well as its conversion product, menaquinone-4 (MK-4)] in tissues obtained from NNK-injected A/J male mice fed 1,25(OH)(2)D3 (2.5 microg/kg diet; D group) +/- RA (15 mg/kg diet) for 20 wk. Renal calcification was only observed in the D group (2/10; 20% of the group). Renal MGP mRNA and uncarboxylated MGP (ucMGP) increased in response to D (P < 0.05) but not in response to RA or RA + D. In contrast, gamma-carboxylated MGP increased to 2.2-fold of the control in response to D+RA (P < 0.05) but not in response to RA or D alone. Although all diets contained equal amounts of PK, the kidney MK-4 concentration was higher in the D group (P < 0.05) and lower in the RA group (P < 0.05) compared with the RA+D or control groups. Renal PK concentrations were lower in the RA and RA+D groups than in the control and D groups (P < 0.05). These data suggest that 9-cis RA mitigated 1,25(OH)(2)D3-induced renal calcification by modifying the 1,25(OH)(2)D3-induced increase in ucMGP. The mechanisms by which 9-cis RA and 1,25(OH)(2)D3 alter vitamin K concentrations warrant further investigation.

Topics: Alitretinoin; Animals; Base Sequence; Calcinosis; Calcitriol; Calcium-Binding Proteins; Carbon-Carbon Ligases; Carcinogens; Dietary Supplements; DNA Primers; Extracellular Matrix Proteins; Kidney Diseases; Liver; Male; Matrix Gla Protein; Mice; Mice, Inbred A; Nitrosamines; RNA, Messenger; Tretinoin; Vitamin K

The transformation of smooth muscle cells (VSMCs) in the vessel wall to osteoblast like cells is known to precede arterial calcification which may cause bleeding complications. The vitamin K-dependent protein MGP has been identified as an inhibitor of this process by binding BMP-2, a growth factor known to trigger the transformation. In this study, we determined if the vitamin K-dependent Gla region in MGP by itself can inhibit the growth factor activity of BMP-2 and if menaquinone-4 (MK4) regulates gene expression in VSMCs.. A synthetic gamma-carboxyglutamic acid (Gla) containing peptide covering the Gla region in human MGP was used to test its ability to inhibit BMP-2 induced transformation of mouse pro-myoblast C2C12 cells into osteoblasts. MK4 was tested by microarray analysis as a gene regulatory molecule in VSMCs.. The results show that the Gla - but not the Glu-peptide inhibited the transformation which provide evidence that the Gla region in MGP is directly involved in the BMP-2/MGP interaction and emphasizes the importance of the vitamin K-dependent modification of MGP. From the data obtained from the microarray analysis, we focused on two quantitatively altered cDNAs representing proteins known to be associated with vessel wall calcification. DT-diaphorase of the vitamin K-cycle, showed increased gene expression with a 4.8-fold higher specific activity in MK4 treated cells. Osteoprotegrin gene expression was down regulated and osteoprotegrin protein secretion from the MK4 treated cells was lowered to 1.8-fold. These findings suggest that MK4 acts as an anti-calcification component in the vessel wall.

Topics: Animals; Antifibrinolytic Agents; Aorta, Thoracic; Bone Morphogenetic Protein 2; Bone Morphogenetic Proteins; Calcinosis; Calcium-Binding Proteins; Cell Differentiation; Cell Line; Extracellular Matrix Proteins; Humans; Matrix Gla Protein; Mice; Muscle, Smooth, Vascular; Myoblasts; Osteoblasts; Peptide Fragments; Rats; Transforming Growth Factor beta; Vitamin K; Vitamin K 2

The aims of the present study were to investigate whether the calcification inhibitor matrix Gla protein (MGP) is expressed in muscle biopsies of patients with juvenile dermatomyositis (JDM), and whether different forms of MGP are differentially expressed in JDM patients with and without subcutaneous calcifications.. Muscle tissue from six JDM patients (three without calcinosis, two with calcinosis and one recently diagnosed patient), four patients with muscular dystrophy, three patients with IBM and five normal histological control subjects was used for immunohistochemistry staining using novel antibodies to different conformations of MGP.. In the JDM patients, all forms of MGP [non-carboxylated MGP (ucMGP), carboxylated MGP (cMGP), non-phosphorylated MGP (serMGP) and phosphorylated MGP (pserMGP)] were more intensely stained in the perifascicular compared with the central muscle fibres. In addition, these MGP species were demonstrated in the pathological muscle fibres of IBM and dystrophy patients, but hardly in normal histological muscle tissue. In JDM patients with calcifications, only pserMGP was increased compared with those without calcifications. All forms of MGP were also found in various staining intensities in the microvasculature and macrophages of normal histological and disease biopsies.. MGP was expressed at the site of muscle damage in JDM patients as well as in patients with muscular dystrophy and IBM. The difference in staining intensity of pserMGP appeared to distinguish between JDM patients with and without calcifications, whereas cMGP, the other functional form, was equally expressed.

Topics: Adolescent; Biomarkers; Calcinosis; Calcium-Binding Proteins; Case-Control Studies; Child; Cohort Studies; Dermatomyositis; Extracellular Matrix Proteins; Female; Humans; Immunohistochemistry; Male; Matrix Gla Protein; Muscle Cells; Muscle, Smooth; Phosphorylation; Reference Values; Sensitivity and Specificity; Tissue Culture Techniques; Vitamin K

Vitamin K is an important co-factor in the production of proteins that inhibit vascular calcification. A low dietary Vitamin K intake has been associated with aortic and coronary calcifications and an elevated cardiovascular risk. Calcifications in the arteries of the breasts have also been associated with cardiovascular risk, but whether there is a relation with a low Vitamin K intake has not yet been studied.. We conducted a cross-sectional study among 1689 women, aged 49-70 years. Dietary Vitamins K1 and K2 intake was calculated from a validated food frequency questionnaire. Breast arterial calcifications (BAC) were assessed on standard screening mammograms by two independent radiologists. With a general linear model mean Vitamins K1, K2 and Vitamin K2 subtypes were calculated for women with BAC and without, adjusted for age, smoking, diabetes, intake of saturated fat, mono-unsaturated fat, poly-unsaturated fat and protein- and calcium-intake.. BAC was less common in the highest (9%) quartile of Vitamin K2 intake, compared to the lowest (13%) (OR 0.7, 95% CI 0.5-1.1) and not different across quartiles of Vitamin K1 intake. Mean Vitamin K2 levels and mean levels of Vitamin K2 subtypes MK-5 through MK-10 were lower in the participants with BAC (p=0.01) compared to participants without BAC. However, after adjustment for aging, smoking, diabetes and dietary factors the association of mean Vitamin K2 intake with BAC was no longer significant.. Calcifications in breast arteries are not associated with a lower dietary intake of Vitamin K.

Topics: Aged; Calcinosis; Cross-Sectional Studies; Diet Records; Europe; Female; Humans; Mammary Arteries; Mammography; Middle Aged; Nutritional Status; Prospective Studies; Vascular Diseases; Vitamin K; Vitamin K Deficiency

Isolated systolic hypertension results from a gradual stiffening of large arteries, to which medial elastocalcinosis (calcification of elastic lamellae) contributes. There is compelling evidence that reactive oxygen species (ROS) are associated with several disease processes affecting the cardiovascular system, including hypertension. The present study was designed to investigate whether the inhibition of ROS production by alpha-lipoic acid can prevent vascular calcification. Sprague-Dawley rats were treated with warfarin (20 mg/kg/day) and vitamin K (15 mg/kg/day) (WVK) for 4 weeks to induce large artery calcification. Subgroups received either a normal diet or a diet supplemented with lipoic acid (1000 mg/kg/day). The WVK treatment produced a small elevation of aortic superoxide levels that did not reach statistical significance. Alpha-lipoic acid reduced the elevation below baseline levels. In rats treated with alpha-lipoic acid, the WVK-induced elevation of pulse wave velocity (an index of arterial stiffness), left ventricular hypertrophy, and aortic, femoral and carotid elastocalcinosis were not prevented. Although a contribution of oxidative stress has been suggested in the aging cardiovascular system, this alteration does not appear to contribute to the calcification process and the subsequent stiffening of large arteries in the animal model tested.

Topics: Animals; Arteries; Calcinosis; Dietary Fats; Hypertrophy, Left Ventricular; Male; Oxidative Stress; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Superoxides; Thioctic Acid; Vascular Diseases; Vitamin K; Warfarin

Arterial calcification (AC) is generally regarded as an independent risk factor for cardiovascular morbidity and mortality. Matrix Gla protein (MGP) is a potent inhibitor of AC, and its activity depends on vitamin K (VK). In rats, inactivation of MGP by treatment with the vitamin K antagonist warfarin leads to rapid calcification of the arteries. Here, we investigated whether preformed AC can be regressed by a VK-rich diet. Rats received a calcification-inducing diet containing both VK and warfarin (W&K). During a second 6-week period, animals were randomly assigned to receive either W&K (3.0 mg/g and 1.5 mg/g, subsequently), a diet containing a normal (5 microg/g) or high (100 microg/g) amount of VK (either K1 or K2). Increased aortic calcium concentration was observed in the group that continued to receive W&K and also in the group changed to the normal dose of VK and AC progressed. Both the VK-rich diets decreased the arterial calcium content by some 50%. In addition, arterial distensibility was restored by the VK-rich diet. Using MGP antibodies, local VK deficiency was demonstrated at sites of calcification. This is the first study in rats demonstrating that AC and the resulting decreased arterial distensibility are reversible by high-VK intake.

Topics: Animals; Aorta, Thoracic; Arteries; Biomechanical Phenomena; Calcinosis; Calcium; Calcium-Binding Proteins; Carotid Arteries; Extracellular Matrix Proteins; Male; Matrix Gla Protein; Rats; Rats, Inbred WKY; Vitamin K; Warfarin

Age-related medial calcification (elastocalcinosis) of large arteries is accelerated in diabetes and appears mainly in distal arteries. The aim was to devise a rat model of elastocalcinosis in association with diabetes to examine the hypothesis that diabetes accelerates vascular calcification experimentally.. Male Wistar rats received a high fat diet during 2 months followed by a low dose of streptozotocin to induce diabetes (D). Elastocalcinosis was facilitated by 3 weeks of treatment with warfarin and vitamin K (WVK). We started WVK treatment 1 week (D4WVK) and 4 weeks (D7WVK) after the injection of streptozotocin and in age-matched healthy rats. Measurements of hemodynamic and metabolic parameters, aortic and femoral calcium content, and immunohistochemistry for alkaline phosphatase, osteopontin, tumor necrosis factor (TNF)-alpha, and transforming growth factor (TGF)-TGF-beta were performed.. Three weeks of WVK treatment alone did not increase the calcium content in the aorta and femoral arteries. However, in the D7WVK group, femoral calcification, but not aortic calcium content, increased significantly as compared to the WVK group. This response was not observed in the D4WVK group. In femoral arteries, strong immunostaining for alkaline phosphatase and osteopontin was observed in the D7WVK group. TNF-alpha and TGF-beta expressions were mainly localized in the adventitia of arteries from diabetic rats.. We have established a model of accelerated elastocalcinosis in diabetes related to its duration and localized in distal arteries. The modification of local protein expression is also in accordance with clinical data, suggesting that this model could be useful to investigate mechanisms related to this important clinical macrovascular complication of diabetes.

Topics: Alkaline Phosphatase; Animals; Aorta; Arteriosclerosis; Calcinosis; Calcium; Diabetes Mellitus, Experimental; Diabetic Angiopathies; Femoral Artery; Immunohistochemistry; Male; Models, Animal; Osteopontin; Rats; Rats, Wistar; Transforming Growth Factor beta; Tumor Necrosis Factor-alpha; Vitamin K; Warfarin

Matrix Gla protein (MGP) is a small vitamin K-dependent protein containing five gamma-carboxyglutamic acid (Gla) residues that are believed to be important in binding Ca(2+), calcium crystals and bone morphogenetic protein. In addition, MGP contains phosphorylated serine residues that may further regulate its activity. In vivo, MGP has been shown to be a potent inhibitor of vascular calcification; however, the precise molecular mechanism underlying the function of MGP is not yet fully understood.. We investigated the effects of MGP in human vascular smooth muscle cell (VSMC) monolayers that undergo calcification after exposure to an increase in Ca(2+) concentration. Increased calcium salt deposition was found in cells treated with the vitamin K antagonist warfarin as compared to controls, whereas cells treated with vitamin K(1) showed decreased calcification as compared to controls. With conformation-specific antibodies, it was confirmed that warfarin treatment of VSMCs resulted in uncarboxylated (Gla-deficient) MGP. To specifically test the effects of MGP on VSMC calcification, we used full-length synthetic MGP and MGP-derived peptides representing various domains in MGP. Full length MGP, the gamma-carboxylated motif (Gla) (amino acids 35-54) and the phosphorylated serine motif (amino acids 3-15) inhibited calcification. Furthermore, we showed that the peptides were not taken up by VSMCs but bound to the cell surface and to vesicle-like structures.. These data demonstrate that both gamma-glutamyl carboxylation and serine phosphorylation of MGP contribute to its function as a calcification inhibitor and that MGP may inhibit calcification via binding to VSMC-derived vesicles.

Topics: 1-Carboxyglutamic Acid; Adolescent; Adult; Amino Acid Sequence; Calcinosis; Calcium; Calcium-Binding Proteins; Cell Membrane; Cells, Cultured; Extracellular Matrix Proteins; Female; Humans; Male; Matrix Gla Protein; Middle Aged; Molecular Sequence Data; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Peptide Fragments; Phosphorylation; Protein Processing, Post-Translational; Protein Structure, Tertiary; Serine; Transport Vesicles; Vitamin K; Vitamin K 1; Warfarin

Matrix gamma-carboxyglutamic acid (Gla) protein (MGP), a vitamin K-dependent protein, is a potent in vivo inhibitor of arterial calcification. We hypothesized that low endogenous production of MGP and impaired carboxylation of MGP may contribute to the development or the progression of vascular disease.. Novel conformation-specific antibodies against MGP were used for immunohistochemistry of healthy and sclerotic arteries. In healthy arteries, MGP was mainly displayed around the elastin fibers in the tunica media. The staining colocalized with that for carboxylated MGP, whereas undercarboxylated MGP (ucMGP) was not detected. In atherosclerotic arteries, ucMGP was found in the intima, where it was associated with vesicular structures. In Mönckeberg's sclerosis of the media, ucMGP was localized around all areas of calcification. The results indicate that ucMGP is strongly associated with vascular calcification of different etiologies. In a separate study, serum MGP concentrations in a cohort of 172 subjects who had undergone percutaneous coronary intervention were significantly reduced compared with an apparently healthy population.. These data show that impaired carboxylation of MGP is associated with intimal and medial vascular calcification and suggest the essentiality of the vitamin K modification to the function of MGP as an inhibitor of ectopic calcification.

Topics: Antibody Specificity; Atherosclerosis; Biomarkers; Calcinosis; Calcium-Binding Proteins; Epitopes; Extracellular Matrix Proteins; Humans; Immunohistochemistry; Matrix Gla Protein; Monckeberg Medial Calcific Sclerosis; Protein Conformation; Tunica Intima; Tunica Media; Vitamin K

Calcification is a common complication in cardiovascular disease and may affect both arteries and heart valves. Matrix gamma-carboxyglutamic acid (Gla) protein (MGP) is a potent inhibitor of vascular calcification, the activity of which is regulated by vitamin K. In animal models, vitamin K antagonists (oral anticoagulants [OACs]) were shown to induce arterial calcification. To investigate whether long-term OAC treatment may induce calcification in humans also, we have measured the grade of aortic valve calcification in patients with and without preoperative OAC treatment. OAC-treated subjects were matched with nontreated ones for age, sex, and disease. Calcifications in patients receiving preoperative OAC treatment were significantly (2-fold) larger than in nontreated patients. These observations suggest that OACs, which are widely used for antithrombotic therapy, may induce cardiovascular calcifications as an adverse side effect.

Topics: Administration, Oral; Aged; Anticoagulants; Aortic Valve; Calcinosis; Cardiovascular Diseases; Female; Humans; Male; Middle Aged; Risk Factors; Thrombosis; Vitamin K

The vitamin K-dependent protein, matrix Gla protein (MGP) is a binding protein for bone morphogenetic protein-2 (BMP-2). Here we present additional evidence that the Ca2+-induced conformer of the vitamin K-dependent Gla region in MGP is involved in BMP-2 binding. Recombinant BMP-2 binds to the Gla-containing region of MGP in the presence of Ca2+. Immunohistochemistry showed that calcified lesions in the aortic wall of aging rats contained elevated concentrations of MGP that was poorly gamma-carboxylated and did not bind BMP-2. In contrast, we were able to identify glandular structures in the mucosa of the rat nasal septum that gave bright fluorescent signals with both antigens; confocal microscopy confirmed their colocalization. These results demonstrate that the BMP-2/MGP complex exists in vivo, consistent with a role for MGP as a BMP-2 inhibitor. Age-related arterial calcification may be a consequence of under-gamma-carboxylation of MGP, allowing unopposed BMP-2 activity.

Topics: Amino Acid Sequence; Animals; Aortic Diseases; Bone Morphogenetic Protein 2; Bone Morphogenetic Proteins; Calcinosis; Calcium; Calcium-Binding Proteins; Cattle; Extracellular Matrix Proteins; Female; Fluorescent Antibody Technique; Growth Hormone; Humans; Immunohistochemistry; Matrix Gla Protein; Microscopy, Confocal; Molecular Sequence Data; Nasal Mucosa; Nasal Septum; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Transforming Growth Factor beta; Vitamin K

To provide a rational basis for recommended daily allowances (RDA) of dietary phylloquinone (vitamin K1) and menaquinone (vitamin K2) intake that adequately supply extrahepatic (notably vascular) tissue requirements.. Vitamin K has a key function in the synthesis of at least two proteins involved in calcium and bone metabolism, namely osteocalcin and matrix Gla-protein (MGP). MGP was shown to be a strong inhibitor of vascular calcification. Present RDA values for vitamin K are based on the hepatic phylloquinone requirement for coagulation factor synthesis. Accumulating data suggest that extrahepatic tissues such as bone and vessel wall require higher dietary intakes and have a preference for menaquinone rather than for phylloquinone.. Tissue-specific vitamin K consumption under controlled intake was determined in warfarin-treated rats using the vitamin K-quinone/epoxide ratio as a measure for vitamin K consumption. Immunohistochemical analysis of human vascular material was performed using a monoclonal antibody against MGP. The same antibody was used for quantification of MGP levels in serum.. At least some extrahepatic tissues including the arterial vessel wall have a high preference for accumulating and using menaquinone rather than phylloquinone. Both intima and media sclerosis are associated with high tissue concentrations of MGP, with the most prominent accumulation at the interface between vascular tissue and calcified material. This was consistent with increased concentrations of circulating MGP in subjects with atherosclerosis and diabetes mellitus.. This is the first report demonstrating the association between MGP and vascular calcification. The hypothesis is put forward that undercarboxylation of MGP is a risk factor for vascular calcification and that the present RDA values are too low to ensure full carboxylation of MGP.

Topics: Arteriosclerosis; Calcinosis; Calcium; Calcium-Binding Proteins; Extracellular Matrix Proteins; Humans; Matrix Gla Protein; Muscle, Smooth, Vascular; Osteocalcin; Vitamin K; Vitamin K 1

High doses of warfarin cause focal calcification of the elastic lamellae in the media of major arteries and in aortic heart valves in the rat. Aortic calcification was first seen after 2 weeks of warfarin treatment and progressively increased in density at 3, 4, and 5 weeks of treatment. By 5 weeks, the highly focal calcification of major arteries could be seen on radiographs and by visual inspection of the artery. The calcification of arteries induced by warfarin is similar to that seen in the matrix Gla protein (MGP)-deficient mouse, which suggests that warfarin induces artery calcification by inhibiting gamma-carboxylation of MGP and thereby inactivating the putative calcification-inhibitory activity of the protein. Warfarin treatment markedly increased the levels of MGP mRNA and protein in calcifying arteries and decreased the level of MGP in serum. Warfarin treatment did not affect bone growth, overall weight gain, or serum calcium and phosphorus levels, and, because of the concurrent administration of vitamin K, prothrombin times and hematocrits were normal. The results indicate that the improved warfarin plus vitamin K treatment protocol developed in this study should provide a useful model to investigate the role of MGP in preventing calcification of arteries and heart valves.

Topics: Animals; Arteries; Calcinosis; Calcium-Binding Proteins; Extracellular Matrix Proteins; Heart Valve Diseases; Male; Matrix Gla Protein; Rats; Rats, Sprague-Dawley; Vascular Diseases; Vitamin K; Warfarin

Calcification of extracellular matrix (ECM) can be either physiological or pathological. Physiological calcification (or mineralization) of ECM is restricted to bones, teeth and, to a lesser extent, growth plate cartilages. Pathological calcification appears often in the ECM of arteries where it is a frequent complication of atherosclerosis. However, calcification of the ECM of arteries is not restricted to atherosclerosis. Indeed, human diseases have been described that are characterized by calcification of the aortic media in the absence of any atherosclerotic lesions. The existence of these rare diseases, along with several mouse models recently generated and discussed below, indicates that the formation of atherosclerotic lesions and the calcification of the artery ECM are controlled by different genetic pathways. This emerging knowledge has implications for our understanding of ECM calcification beyond atherosclerosis.

Topics: Animals; Arteries; Arteriosclerosis; Calcinosis; Calcium-Binding Proteins; Extracellular Matrix; Extracellular Matrix Proteins; Glycoproteins; Humans; Matrix Gla Protein; Mice; Osteoprotegerin; Receptors, Cytoplasmic and Nuclear; Receptors, Tumor Necrosis Factor; Vascular Diseases; Vitamin K

The effect of vitamin K2 on calcium (Ca) and inorganic phosphorus (P) levels in the aorta and kidney obtained from experimental calcinosis induced by vitamin D2(2.5 x 10(5) I.U./ kg b.w.) of male rats was investigated. A high dose of vitamin K2 (100 mg/kg b.w.) inhibited the increase in the aortic Ca and P or in the renal Ca and P induced by vitamin D2, and a low dose of vitamin K2 (10 mg/kg b.w.) showed the same tendency, but the degree of the efficacy was small. It may be suggested that a high dose of vitamin K2 suppressed experimental calcification of soft tissues induced by vitamin D2. Therefore, a pharmacological dose of vitamin K2 might have a usefulness for the prevention and treatment of arteriosclerosis with calcification.

Topics: Animals; Aorta; Calcinosis; Calcium; Ergocalciferols; Kidney; Male; Phosphorus; Rats; Rats, Sprague-Dawley; Vitamin K

Protein-bound gamma-carboxyglutamate (Gla) has been demonstrated in calcified atherosclerotic plaques. Vitamin K is required for the formation of Gla-residues. As the biological activity of Gla-proteins appears to be strictly dependent on the presence of the Gla-residues, vitamin K status may be an important factor in the development and progression of atherosclerotic calcifications. We studied the association of vitamin K status, as assessed by nutritional vitamin K intake and the measurements of two circulating immunoreactive osteocalcin (irOC) fractions, with aortic atherosclerosis in a population-based study of 113 postmenopausal women. Women with calcified lesions (n = 34) had a 42.9 micrograms lower mean age-adjusted dietary vitamin K intake/day (95% C.I. -6.6 to 92.5) than those without calcifications (n = 79). Atherosclerotic women had higher irOC levels with a low affinity for hydroxyapatite (irOCfree): age-adjusted difference of 0.32 ng/ml (95% C.I. 0.03 to 0.61). In addition, the high affinity irOC levels expressed as a percentage (hydroxyapatite binding capacity, HBC) were 5.12% (95% C.I. 1.32 to 8.92) lower in women with calcifications. Our study indicates that women with aortic atherosclerosis have an impaired vitamin K status as reflected by a lower nutritional vitamin K intake, an increased irOCfree level and a reduced HBC level. An impaired vitamin K status in subjects with atherosclerosis is compatible with the view that vitamin K or Gla-containing proteins are involved in the development of calcification of the vessel wall.

Topics: 1-Carboxyglutamic Acid; Aged; Aorta, Abdominal; Aortic Diseases; Arteriosclerosis; Body Constitution; Body Mass Index; Calcinosis; Chromatography, Affinity; Cohort Studies; Diet; Durapatite; Female; Humans; Middle Aged; Osteocalcin; Vitamin K; Vitamin K Deficiency

Topics: Calcinosis; Female; Humans; Middle Aged; Renal Dialysis; Vitamin K

Vitamin K promotes the formation of gamma-carboxylated glutamic acid (Gla) residues within different protein classes such as vitamin K-dependent clotting factors, bone Gla-protein (BGP or osteocalcin), and atherocalcin. Gla-containing proteins have a high affinity for the Ca2+ ion. In addition to bone and atheromatous plaques they are also regularly found in ectopic calcifications, but not in uncalcified soft tissue. In the present study we investigate the possibility that vitamin K and BGP, in addition to previously recognized factors, may play a role in soft tissue calcification of chronic hemodialysis patients. Patients without radiovisible ectopic calcifications (group A) are compared to patients with such Ca deposits (group B). Both patient groups have comparable values of predialysis plasma Ca, P, alkaline phosphatases, parathyroid hormone (PTH) and 25 hydroxyvitamin D. The CaxP product is slightly higher in group B than in group A patients. Plasma vitamin K1 levels of group B patients are increased to more than twice the values observed in group A patients. Plasma BGP, even though not significantly different, shows a trend towards decreased levels in group B patients. A positive correlation exists between plasma vitamin K1 and BGP for patient group A alone, but not for group B alone. A correlation is also observed between plasma PTH and BGP (all patients) and between serum alkaline phosphatases and plasma BGP (all patients). Taken together, these results favor the hypothesis that in addition to an increased CaxP product a vitamin K excess may induce soft tissue calcification in hemodialysis patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adult; Aged; Calcinosis; Calcium; Calcium-Binding Proteins; Connective Tissue Diseases; Female; Humans; Male; Middle Aged; Osteocalcin; Parathyroid Hormone; Renal Dialysis; Uremia; Vitamin K; Vitamin K 1

Topics: Calcinosis; Granuloma; Humans; Lipid Metabolism; Male; Middle Aged; Skin Diseases, Vesiculobullous; Vitamin K

Calcium binding proteins containing gamma-carboxyglutamic acid (Gla) have previously been demonstrated to occur in calcified atherosclerotic plaque and calcified cardiac valves. Experiments were carried out to determine if one of the Gla-containing proteins in human cardiovascular calcifications is the vitamin K-dependent bone protein, osteocalcin. A radio-immunoassay for human osteocalcin was employed, and EDTA extractions of calcified atheromata, and aortic valves as well as relevant noncalcified material were analyzed. Tissue calcium levels were also determined, as were Gla levels as a measure of total vitamin K-dependent protein content. Osteocalcin was present at low levels in all calcified cardiovascular tissues (4.5-175.7 ng osteocalcin/mg protein) with trace levels or nondetectable amounts present in noncalcified tissue. Osteocalcin accounted for a small proportion of the total protein-bound Gla (0.01-0.05%). The relationship of osteocalcin to the other Gla-containing proteins of atherosclerotic plaque including atherocalcin, the principal extractable Gla-containing protein of calcified plaque, is discussed.

Topics: 1-Carboxyglutamic Acid; Adult; Aged; Arteriosclerosis; Bone and Bones; Calcinosis; Calcium-Binding Proteins; Child; Child, Preschool; Glutamates; Heart Valves; Humans; Middle Aged; Osteocalcin; Proteins; Vitamin D; Vitamin K

The pathogenesis of valvar calcification, which complicates the course of cardiac valve disease and also affects tissue valve prostheses, is incompletely understood. The present work explores the possible role of the vitamin K-dependent, calcium-binding amino acid, gamma-carboxyglutamic acid (Gla) in valve mineralization. Gla is normally found in the vitamin K-dependent clotting factor proteins, and is also present in unique calcium binding proteins in bone, kidney, and lung. Unique Gla-containing proteins have also been isolated from pathologic calcifications including calcium containing renal stones and calcified atherosclerotic plaque. Calcified valves including specimens with calcific aortic stenosis, calcified porcine xenograft valves, and a calcified aortic homograft valve were analyzed for Gla content, complete amino acid analysis, and tissue calcium and phosphorus levels. Normal porcine valves contained protein-bound Gla (2.0-10.6 Gla/10(4) amino acids): no Gla was present in normal valve leaflets. Furthermore, Gla levels paralleled tissue calcium content in the calcified valves. In addition, complete amino acid analysis indicated a decline in valvar collagen content plus increased acidic proteins in conjunction with valvar calcification and the presence of Gla-containing proteins. These results suggest that calcific valvar disease may result in part from vitamin K-dependent processes.

Topics: 1-Carboxyglutamic Acid; Animals; Aortic Valve; Aortic Valve Stenosis; Bioprosthesis; Calcinosis; Calcium-Binding Proteins; Heart Valve Diseases; Humans; Transplantation, Homologous; Vitamin K

Bone, whether of endochondral or intramembranous origin, contains the vitamin K-dependent calcium binding amino acid residue gamma-carboxyglutamic acid (Gla) in a small, anionic protein we have named osteocalcin. This protein, which constitutes 0.5 to 1.0% of the total bone proteins and about 20% of the noncollagenous protein, is extractable by EDTA, and contains at least 90% of bone Gla. Analysis of purified osteocalcin from chicken bone and independent sequence studies of an analogous bovine bone protein show no apparent homology to the Gla-containing region of prothrombin. Chicken osteocalcin specifically binds 2 moles of calcium ions per 6,500 g protein. Employing coumarin drugs and vitamin K-deficient diets, vitamin K-dependent osteocalcin biosynthesis has been demonstrated in the chick before and after hatching. Organ cultures of embryonic chick bone show de novo synthesis of osteocalcin, and microsomal preparations of embryonic bone also exhibit vitamin K-dependent carboxylase activity. In addition to the presence of osteocalcin in bone, a Gla-protein of unknown function is present in normal nonmineralized kidney cortex. Furthermore, in various pathological calcifications such as hard atheromatous plaque, renal calculi, and subcutaneous ectopic calcifications other Gla-proteins are found, thus implicating such proteins and vitamin K in many facets of calcium metabolism.

Topics: 1-Carboxyglutamic Acid; Animals; Bone and Bones; Bone Development; Calcification, Physiologic; Calcinosis; Calcium; Carboxy-Lyases; Carrier Proteins; Chickens; Culture Techniques; Microsomes; Vitamin K