Chronic coumarin treatment is associated with increased extracoronary arterial calcification in humans

Effects of menaquinone-7 supplementation in patients with aortic valve calcification: study protocol for a randomised controlled trial

INTRODUCTION

Aortic stenosis is a common heart valve disease, and due to the growing elderly population, the prevalence is increasing. The disease is progressive with increasing calcification of the valve cusps. A few attempts with medical preventive treatment have failed; thus, presently, the only effective treatment of aortic stenosis is surgery. This study will examine the effect of menaquinone-7 (MK-7) supplementation on progression of aortic valve calcification (AVC). We hypothesise that MK-7 supplementation will slow down the calcification process.

METHODS AND ANALYSIS

In this multicenter and double-blinded, placebo-controlled study, 400 men aged 65-74 years with substantial AVC are randomised (1:1) to treatment with MK-7 (720 µg/day) supplemented by the recommended daily dose of vitamin D (25 µg/day) or placebo treatment (no active treatment) for 2 years. Exclusion criteria are treatment with vitamin K antagonist or coagulation disorders. To evaluate AVC score, a non-contrast CT scan is performed at baseline and repeated after 12 and 24 months of follow-up. Primary outcome is difference in AVC score from baseline to follow-up at 2 years. Intention-to-treat principle is used for all analyses.

ETHICS AND DISSEMINATION

There are no reported adverse effects associated with the use of MK-7. The protocol is approved by the Regional Scientific Ethical Committee for Southern Denmark (S-20170059) and the Data Protection Agency (17/19010). It is conducted in accordance with the Declaration of Helsinki. Positive as well as negative findings will be reported.

TRIAL REGISTRATION NUMBER

NCT03243890.

Calcification of the heart: mechanisms and therapeutic avenues

INTRODUCTION

Coronary artery calcification (CAC) is reflective of atherosclerotic disease and incrementally predictive of future cardiovascular events (CVE), independent of traditional risk factors. Extra coronary calcium such as aortic valve calcification, which can be identified and quantified by computed tomography (CT) imaging, has shown to predict future CVE in both asymptomatic and symptomatic (i.e. stable angina and acute coronary syndrome [ACS]) settings. It has hence been a vital tool in studies involving new therapies for cardiovascular disease. Areas covered: In this review, promising therapies on the horizon are reviewed, along with the role of cardiac CT and coronary calcification in these studies. A Medline search for peer-reviewed publications using keywords related to coronary calcium score, aortic valve calcium, and therapies targeting the same was carried out. Expert commentary: CT scanning provides a distinct means of detecting and quantifying coronary plaque as well as valvular calcification with excellent reproducibility. Based on voluminous data available, the absence of coronary calcium serves as a factor to de-risk patients for cardiovascular risk stratification and management algorithms. Newer therapies have shown to lower progression of coronary calcification, thus being beneficial in slowing progression of atherosclerotic disease. As British Epidemiologist Geoffrey Rose states, the best predictor of a life-threatening disease is the early manifestation of that disease. As CAC represents the early manifestation of atherosclerosis, it is the best-known stratifier of risk today, and its clinical use will continue to rise.

Stabilization of warfarin-binding pocket of VKORC1 and VKORL1 by a peripheral region determines their different sensitivity to warfarin inhibition

Essentials VKORL1 and VKORC1 have a similar overall structure and warfarin-binding pocket. A peripheral region stabilizing this pocket controls warfarin sensitivity of the VKOR paralogs. A human single nucleotide polymorphism in this region renders VKORL1 sensitive to warfarin. A group of warfarin-resistant mutations in VKORC1 acts by disrupting peripheral interactions.

SUMMARY

Background The human genome encodes two paralogs of vitamin-K-epoxide reductase, VKORC1 and VKORL1, that support blood coagulation and other vitamin-K-dependent processes. Warfarin inhibits both enzymes, but VKORL1 is relatively resistant to warfarin. Objectives To understand the difference between VKORL1 and VKORC1, and the cause of warfarin-resistant (WR) mutations in VKORC1. Methods We performed systematic mutagenesis and analyzed warfarin responses with a cell-based activity assay. Mass spectrometry analyses were used to detect cellular redox state. Results VKORC1 and VKORL1 adopt a similar intracellular redox state with four-transmembrane-helix topology. Most WR mutations identified in VKORC1 also confer resistance in VKORL1, indicating that warfarin inhibits these paralogs at a common binding site. A group of WR mutations, distant from the warfarin-binding site, show significantly less resistance in VKORL1 than in VKORC1, implying that their different warfarin responses are determined by peripheral interactions. Remarkably, we identify a critical peripheral region in which single mutations, Glu37Lys or His46Tyr, drastically increase the warfarin sensitivity of VKORL1. In the background of these warfarin-sensitive VKORL1 mutants, WR mutations showing relative less resistance in wild-type VKORL1 become much more resistant, suggesting a structural conversion to resemble VKORC1. At this peripheral region, we also identified a human single nucleotide polymorphism that confers warfarin sensitivity of VKORL1. Conclusions Peripheral regions of VKORC1 and VKORL1 primarily maintain the stability of their common warfarin-binding pocket, and differences of such interactions determine their relative sensitivity to warfarin inhibition. This new model also explains most WR mutations located at the peripheral regions of VKORC1.

Is Matrix Gla Protein Associated with Vascular Calcification? A Systematic Review

Specific patient cohorts are at increased risk of vascular calcification. Functional matrix-gla protein (MGP), a tissue-derived vitamin K dependent protein, is reported to be an important inhibitor of vascular calcification and may have clinical potential to modify the progression of vascular calcification through regulation of functional MGP fractions. This systematic review examines twenty-eight studies which assess the relationship between circulating protein expressions of MGP species and vascular calcification in different arterial beds. The included studies examined participants with atherosclerosis, chronic kidney disease (CKD), diabetes, healthy participants, vitamin K supplementation, measured plasma vitamin K levels and vitamin K antagonist usage. The current review reports conflicting results regarding MGP fractions with respect to local calcification development indicating that a multifaceted relationship exists between the MGP and calcification. A primary concern regarding the studies in this review is the large degree of variability in the calcification location assessed and the fraction of MGP measured. This review suggests that different underlying molecular mechanisms can accelerate local disease progression within the vasculature, and specific circulating fractions of MGP may be influenced differently depending on the local disease states related to vascular calcification development. Further studies examining the influence of non-functional MGP levels, with respect to specific calcified arterial beds, are warranted.

Should vitamin K be supplemented instead of antagonised in patients with idiopathic pulmonary fibrosis?

INTRODUCTION

There is an ongoing need for additional interventions in idiopathic pulmonary fibrosis (IPF) as antifibrotic drugs currently available only inhibit and do not stall disease progression. Vitamin K is a co-factor for the activation of coagulation factors. However, it is also required to activate proteins with functions outside of the coagulation cascade, such as matrix Gla protein (MGP), a defender against soft tissue calcification. Vitamin K antagonists are anticoagulants that are, for unknown reasons, associated with increased mortality in IPF. Areas covered: We advance the hypothesis that modulation of vitamin K-dependent MGP activation in IPF patients by either vitamin K antagonism or administration may result in acceleration and deceleration of fibrosis progression, respectively. Furthermore, shortfall in vitamin K could be suspected in IPF based on the high prevalence of certain co-morbidities, such as vascular calcification and lung cancer. Expert commentary: We hypothesize that vitamin K status is reduced in IPF patients. This, in combination with studies suggesting that vitamin K may play a role in lung fibrosis pathogenesis, would provide a rationale for conducting a clinical trial assessing the potential mitigating effects of vitamin K administration on progression of lung fibrosis, prevention of co-morbidities and mortality in IPF.

Vitamin K deficiency: the linking pin between COPD and cardiovascular diseases?

Cardiovascular diseases are prevalent in patients with chronic obstructive pulmonary disease (COPD). Their coexistence implies that many COPD patients require anticoagulation therapy. Although more and more replaced by direct oral anticoagulants, vitamin K antagonists (VKAs) are still widely used. VKAs induce profound deficiency of vitamin K, a key activator in the coagulation pathway. It is recognized however that vitamin K is also an essential cofactor in the activation of other extrahepatic proteins, such as matrix Gla protein (MGP), a potent inhibitor of arterial calcification. No or insufficient MGP activation by the use of VKAs is associated with a rapid progression of vascular calcification, which may enhance the risk for overt cardiovascular disease. Vitamin K consumption, on the other hand, seems to have a protective effect on the mineralization of arteries. Furthermore, vascular calcification mutually relates to elastin degradation, which is accelerated in patients with COPD associating with impaired survival. In this commentary, we hypothesize that vitamin K is a critical determinant to the rate of elastin degradation. We speculate on the potential link between poor vitamin K status and crucial mechanisms of COPD pathogenesis and raise concerns about the use of VKAs in patients with this disease. Future intervention studies are needed to explore if vitamin K supplementation is able to reduce elastin degradation and vascular calcification in COPD patients.

Vitamin K deficit and elastolysis theory in pulmonary elasto-degenerative diseases

Elastin is a unique protein providing deformability and resilience to dynamic tissues, such as arteries and lungs. It is an absolute basic requirement for circulation and respiration. Elastin can be degraded by elastases and has a high calcium affinity. Elastin calcification and elastin degradation are two pathological processes that impair elastin's functioning. Furthermore, elastin degradation can be associated to elastin calcification. Matrix Gla Protein (MGP) is probably the most potent natural inhibitor of elastin calcification and requires vitamin K for its activation. Measuring circulating levels of inactive MGP (dp-ucMGP) is a frequently used method to assess vitamin K status. Dp-ucMGP reflects the burden of vitamin K-dependent proteins that have not been activated by vitamin K and could therefore best be regarded as a biomarker of a vitamin K deficit. Dp-ucMGP levels decrease after vitamin K supplementation. Since the amino acids desmosine and isodesmosine (DES) are unique to crosslinked elastin fibers, systemic elastin degradation can be assessed with the plasma DES assay. Recently, we discovered a strong correlation between plasma dp-ucMGP and plasma DES levels in both patients with chronic obstructive pulmonary disease (COPD) and controls. The 'Vitamin K deficit and elastolysis theory' posits that elastin degradation causes a rise in the vitamin K deficit and implies that vitamin K supplementation could be preventing elastin degradation. If this hypothesis holds true and is universally found in every state and condition, it will have an unprecedented impact on the management of every single pulmonary disease characterized by accelerated elastin degradation, such as alpha-1 antitrypsin deficiency, bronchiectasis, COPD and cystic fibrosis. Theoretically, a plasma dp-ucMGP concentration of zero would be associated with a near-complete standstill of elastin degradation and disease progression in patients with any of these debilitating conditions.

Dietary reference values for vitamin K

Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) derives dietary reference values (DRVs) for vitamin K. In this Opinion, the Panel considers vitamin K to comprise both phylloquinone and menaquinones. The Panel considers that none of the biomarkers of vitamin K intake or status is suitable by itself to derive DRVs for vitamin K. Several health outcomes possibly associated with vitamin K intake were also considered but data could not be used to establish DRVs. The Panel considers that average requirements and population reference intakes for vitamin K cannot be derived for adults, infants and children, and therefore sets adequate intakes (AIs). The Panel considers that available evidence on occurrence, absorption, function and content in the body or organs of menaquinones is insufficient, and, therefore, sets AIs for phylloquinone only. Having assessed additional evidence available since 1993 in particular related to biomarkers, intake data and the factorial approach, which all are associated with considerable uncertainties, the Panel maintains the reference value proposed by the Scientific Committee for Food (SCF) in 1993. An AI of 1 μg phylloquinone/kg body weight per day is set for all age and sex population groups. Considering the respective reference body weights, AIs for phylloquinone are set at 70 μg/day for all adults including pregnant and lactating women, at 10 μg/day for infants aged 7-11 months, and between 12 μg/day for children aged 1-3 years and 65 μg/day for children aged 15-17 years.

Vitamin K Antagonist Therapy Is a Risk Factor for Ulcer Development and Death Among Dialyzed Patients

Peripheral artery disease is a common complication among dialyzed patients. Since Vitamin K antagonists promote metastatic calcifications and these are the main determinants of vascular damage, we investigated their role in the development of lower limb ulcers in dialyzed patients. We retrospectively enrolled 316 dialyzed patients, aged 68 ± 15 years, 65% male, 32% diabetic, 43% with ischemic heart disease and followed them for 36 ± 25 months. 60 patients assumed Vitamin K antagonists: they were older, with a higher prevalence of heart disease, at greater risk of death and they developed more ulcers and underwent more lower limb amputations compared to the rest of our cohort. Peripheral artery disease, Vitamin K antagonists and diabetes were independent risk factors for foot lesions. In addition, Vitamin K antagonists were also an independent risk factor for death. Vitamin K antagonists are a potent independent risk factor for the development of the uremic foot syndrome and death.

Warfarin and Vascular Calcification

The vitamin K antagonist, warfarin, is the most commonly prescribed oral anticoagulant. Use of warfarin is associated with an increase in systemic calcification, including in the coronary and peripheral vasculature. This increase in vascular calcification is due to inhibition of the enzyme matrix gamma-carboxyglutamate Gla protein (MGP). MGP is a vitamin K-dependent protein that ordinarily prevents systemic calcification by scavenging calcium phosphate in the tissues. Warfarin-induced systemic calcification can result in adverse clinical effects. In this review article, we highlight some of the key translational and clinical studies that associate warfarin with vascular calcification.

Impact of menaquinone-4 supplementation on coronary artery calcification and arterial stiffness: an open label single arm study

Background

Dietary intake of vitamin K has been reported to reduce coronary artery calcification (CAC) and cardiovascular events. However, it is unknown whether supplemental menaquinone (MK)-4 can reduce CAC or arterial stiffness. To study the effect of MK-4 supplementation on CAC and brachial ankle pulse wave velocity (baPWV).

Methods

This study is a single arm design to take 45 mg/day MK-4 daily as a therapeutic drug for 1 year. Primary endpoint was CAC score determined using 64-slice multislice CT (Siemens), and the secondary endpoint was baPWV measured before and 1 year after MK-4 therapy.

Results

A total of 26 patients were enrolled. The average age was 69 ± 8 years and 65 % were female. Plasma levels of phylloquinone (PK), MK-7, and MK4 were 1.94 ± 1.38 ng/ml, 14.2 ± 11.9 ng/ml and 0.4 ± 2.0 ng/ml, respectively, suggesting that MK-7 was the dominant vitamin K in the studied population. Baseline CAC and baPWV were 513 ± 773 and 1834 ± 289 cm/s, respectively. At 1 year following MK-4 supplementation, the values were 588 ± 872 (+14 %) and 1821 ± 378 cm/s (−0.7 %), respectively. In patients with high PIVKA-2, −18 % annual reduction of baPWV was observed.

Conclusion

Despite high dose MK-4 supplementation, CAC increased +14 % annually, but baPWV did not change (−0.7 %). The benefits of MK-4 supplementation were only observed in patients with vitamin K insufficiencies correlated with high PIVKA-2 baseline levels, reducing baPWV but not CAC.

Trial registration

This study was registered as UMIN 000002760

Increased Peripheral Arterial Calcification in Patients Receiving Warfarin

BACKGROUND

Matrix Gla protein is a vitamin K-dependent inhibitor of vascular calcification. Warfarin use is associated with increased breast arterial calcification, but whether this is reflective of other arteries or occurs in men is unclear. In this study, the prevalence of calcification in peripheral arteries was compared in patients with and without warfarin therapy.

METHODS AND RESULTS

This retrospective matched cohort study assessed 430 patients with radiographs performed during or after warfarin therapy who were identified by a computerized search of medical records. Each patient was matched to a patient without warfarin exposure based on age, sex, and diabetes status. Patients with warfarin exposure <1 month, history of end-stage renal disease, or serum creatinine >2.0 mg/dl were excluded. Radiographs were reviewed visually for arterial calcification. The prevalence of arterial calcification was 44% greater in patients with versus without warfarin use (30.2% versus 20.9%, P=0.0023) but not on radiographs performed before warfarin therapy (26.4% versus 22.4%, n=156) or prior to 5 years of warfarin therapy. The increase was noted only in the ankle and foot, was limited to a medial pattern of calcification, and was similar in men and women.

CONCLUSIONS

Warfarin use is associated with lower extremity arterial calcification in both men and women independent of age, sex, diabetes status, and other patient characteristics. This may have implications for the choice of therapies for long-term anticoagulation.

Menaquinone-7 Supplementation to Reduce Vascular Calcification in Patients with Coronary Artery Disease: Rationale and Study Protocol (VitaK-CAC Trial)

Coronary artery calcification (CAC) develops early in the pathogenesis of atherosclerosis and is a strong and independent predictor of cardiovascular disease (CVD). Arterial calcification is caused by an imbalance in calcification regulatory mechanisms. An important inhibitor of calcification is vitamin K-dependent matrix Gla protein (MGP). Both preclinical and clinical studies have shown that inhibition of the vitamin K-cycle by vitamin K antagonists (VKA) results in elevated uncarboxylated MGP (ucMGP) and subsequently in extensive arterial calcification. This led us to hypothesize that vitamin K supplementation may slow down the progression of calcification. To test this, we designed the VitaK-CAC trial which analyses effects of menaquinone-7 (MK-7) supplementation on progression of CAC. The trial is a double-blind, randomized, placebo-controlled trial including patients with coronary artery disease (CAD). Patients with a baseline Agatston CAC-score between 50 and 400 will be randomized to an intervention-group (360 microgram MK-7) or a placebo group. Treatment duration will be 24 months. The primary endpoint is the difference in CAC-score progression between both groups. Secondary endpoints include changes in arterial structure and function, and associations with biomarkers. We hypothesize that treatment with MK-7 will slow down or arrest the progression of CAC and that this trial may lead to a treatment option for vascular calcification and subsequent CVD.

High-Dose Menaquinone-7 Supplementation Reduces Cardiovascular Calcification in a Murine Model of Extraosseous Calcification

Cardiovascular calcification is prevalent in the aging population and in patients with chronic kidney disease (CKD) and diabetes mellitus, giving rise to substantial morbidity and mortality. Vitamin K-dependent matrix Gla-protein (MGP) is an important inhibitor of calcification. The aim of this study was to evaluate the impact of high-dose menaquinone-7 (MK-7) supplementation (100 µg/g diet) on the development of extraosseous calcification in a murine model. Calcification was induced by 5/6 nephrectomy combined with high phosphate diet in rats. Sham operated animals served as controls. Animals received high or low MK-7 diets for 12 weeks. We assessed vital parameters, serum chemistry, creatinine clearance, and cardiac function. CKD provoked increased aortic (1.3 fold; p < 0.05) and myocardial (2.4 fold; p < 0.05) calcification in line with increased alkaline phosphatase levels (2.2 fold; p < 0.01). MK-7 supplementation inhibited cardiovascular calcification and decreased aortic alkaline phosphatase tissue concentrations. Furthermore, MK-7 supplementation increased aortic MGP messenger ribonucleic acid (mRNA) expression (10-fold; p < 0.05). CKD-induced arterial hypertension with secondary myocardial hypertrophy and increased elastic fiber breaking points in the arterial tunica media did not change with MK-7 supplementation. Our results show that high-dose MK-7 supplementation inhibits the development of cardiovascular calcification. The protective effect of MK-7 may be related to the inhibition of secondary mineralization of damaged vascular structures.

A four-season molecule: osteocalcin. Updates in its physiological roles

Osteocalcin (OC) is the main non-collagenous hydroxyapatite-binding protein synthesized by osteoblasts, odontoblasts, and hypertrophic chondrocytes. It has a regulatory role in mineralization and it is considered a marker of bone cell metabolism. Recent findings evidenced new extra-skeletal roles for OC, depicting it as a real hormone. OC shares many functional features with the common hormones, such as tissue-specific expression, circadian rhythm, and synthesis as a pre-pro-molecule. However, it has some peculiar features making it a unique molecule: OC exists in different forms based on the degree of carboxylation. Indeed, OC has three glutamic acid residues, in position 17, 21, and 24, which are subject to γ-carboxylation, through the action of a vitamin K-dependent γ-glutamyl carboxytransferase. The degree of carboxylation, and thus the negative charge density, determines the affinity for the calcium ions deposited in the extracellular matrix of the bone. The modulation of the carboxylation could, thus, represent the mechanism by which the body controls the circulating levels, and hence the hormonal function, of OC. There are evidences linking OC, and the bone metabolism, with a series of endocrine (glucose metabolism, energy metabolism, fertility) physiological (muscle activity) and pathological functions (ectopic calcification). Aim of this review is to give a full overview of the physiological roles of OC by collecting the newest experimental findings on this intriguing molecule.

Canola and hydrogenated soybean oils accelerate ectopic bone formation induced by implantation of bone morphogenetic protein in mice

Canola oil (Can) and hydrogenated soybean oil (H2-Soy) are commonly used edible oils. However, in contrast to soybean oil (Soy), they shorten the survival of stroke-prone spontaneously hypertensive (SHRSP) rats. It has been proposed that the adverse effects of these oils on the kidney and testis are caused at least in part by dihydro-vitamin K (VK) 1 in H2-Soy and unidentified component(s) in Can. Increased intake of dihydro-VK1 is associated with decreased tissue VK2 levels and bone mineral density in rats and humans, respectively. The aim of the present study was to determine the effects of these oils on bone morphogenetic protein (BMP)-induced ectopic bone formation, which is promoted by VK2 deficiency, in relation to the role of VK in the γ-carboxylation of osteocalcin and matrix Gla protein. A crude extract of BMPs was implanted into a gap in the fascia of the femoral muscle in 5-week-old mice maintained on a Soy, Can, or H2-Soy diet. Newly formed bone volume, assessed by three-dimensional X-ray micro-computed tomography and three-dimensional reconstruction imaging for bone, was 4-fold greater in the Can and H2-Soy groups than in the Soy group. The plasma carboxylated osteocalcin (Gla-OC) and total OC (Gla-OC plus undercarboxylated osteocalcin [Glu-OC]) levels were significantly lower in the Can group than in the Soy group (p < 0.05). However, these levels did not significantly differ between the H2-Soy and Soy groups. The plasma Gla-OC/Glu-OC ratio in the Can and H2-Soy groups was significantly lower (in Can; p = 0.044) or was almost significantly lower (in H2-Soy; p = 0.053) than that in the Soy group. In conclusion, Can and H2-Soy accelerated BMP-induced bone formation in mice to a greater extent than Soy. Further research is required to evaluate whether the difference in accelerated ectopic bone formation is associated with altered levels of VK2 and VK-dependent protein(s) among the three dietary groups.

Increased vascular calcification in patients receiving warfarin

OBJECTIVE

Matrix gla protein is a vitamin K-dependent inhibitor of medial arterial calcification whose synthesis and activity are blocked by warfarin. Warfarin induces arterial calcification in experimental models, but whether this occurs in humans is unclear. This was addressed by examining breast arterial calcification, which is exclusively medial and easily identified on mammograms.

APPROACH AND RESULTS

Screening mammograms from women with current, past, or future warfarin use were examined for the presence of arterial calcification and compared with mammograms obtained in untreated women matched for age and diabetes mellitus. Women with a serum creatinine >2.0 mg/dL or a history of end-stage renal disease were excluded. In 451 women with mammograms performed after ≥1 month of warfarin therapy, the prevalence of arterial calcification was 50% greater than in 451 untreated women (39.0% versus 25.9%; P<0.0001). However, in 159 mammograms performed before warfarin therapy, the prevalence of arterial calcification was not increased (26.4% versus 25.8%). The increased prevalence varied with duration of treatment, from 25.0% for <1 year to 74.4% for >5 years. In a multivariable logistic model, only age and duration of warfarin, but not the period of time after stopping warfarin, were significant determinants of arterial calcification in women with current or past warfarin use.

CONCLUSIONS

The prevalence of breast arterial calcification is increased in women with current or past warfarin use independent of other risk factors and conditions predating warfarin use. This effect appears to be cumulative and may be irreversible.

Circulating desphospho-uncarboxylated matrix γ-carboxyglutamate protein and the risk of coronary heart disease and stroke

BACKGROUND

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.

OBJECTIVE

To investigate the association of dp-ucMGP with incident CHD or stroke.

METHODS

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.

RESULTS AND CONCLUSION

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.

Vitamin k dependent proteins and the role of vitamin k2 in the modulation of vascular calcification: a review

Vascular calcification, a cause of cardiovascular morbidity and mortality, is an actively regulated process involving vitamin K dependent proteins (VKDPs) among others. Vitamin K is an essential micronutrient, present in plants and animal fermented products that plays an important role as a cofactor for the post-translational γ-carboxylation of glutamic acid residues in a number of proteins. These VKDPs require carboxylation to become biologically active, and they have been identified as having an active role in vascular cell migration, angiogenesis and vascular calcification. This paper will review the process of vascular calcification and delineate the role that vitamin K2 plays in the modulation of that process, through the activation of VKDPs. One such VKDP is Matrix Gla Protein (MGP), which when activated inhibits osteogenic factors, thereby inhibiting vascular and soft tissue calcification.

New insights into modulation of thrombin formation

Thrombin is a pleiotropic enzyme that regulates hemostasis and nonhemostatic functions, including an array of actions within and on the vasculature. Physiologically, thrombin generation serves mainly to protect against thrombosis, but also to maintain vascular endothelial integrity. This protective effect is mediated in part through generation of anticoagulant enzymes, including activated protein C, formed on the action of thrombin on the endothelial receptor thrombomodulin. Partly, thrombin's vascular effects are effectuated through interaction with protease-activated receptors on various cell types. Pathophysiologically, downregulation and shedding of anticoagulant-acting receptors such as thrombomodulin and endothelial protein C receptor may contribute to a shift in activities of thrombin towards thrombogenic and proinflammatory actions. This shift may typically occur in the process of atherosclerosis, leading to a proatherogenic direction of the effects of thrombin. Therapeutically, the long-term inhibition of thrombin may create new ways of reducing atherosclerosis burden, altering the plaque phenotype.

Impact of Incident Venous Thromboembolism on Risk of Arterial Thrombotic Diseases

Background—

Growing evidence supports an association between venous thromboembolism (VTE) and arterial thrombotic diseases (ie, myocardial infarction and ischemic stroke). We aimed to study the association between VTE and future arterial events and to determine the population attributable risk of arterial events by VTE in a large prospective cohort recruited from the general population.

Methods and Results—

In 1994 to 1995 and 1993 to 1997, 81 687 subjects were included in the Tromsø Study and in the Diet, Cancer and Health Study and followed up to the date of incident venous and arterial events (myocardial infarction or ischemic stroke), death or migration, or to the end of the study period (2010 and 2008, respectively). There were 1208 cases of VTE and 90 subsequent arterial events during a median follow-up of 12.2 years. An association between VTE and future arterial events was found in all women and men aged <65 years but not in men aged >65 years. Women <65 years old with VTE had 3.3-fold higher risk of arterial disease (adjusted hazard ratio, 3.28; 95% confidence interval, 1.69–6.35) compared with women of the same age without VTE. The corresponding hazard ratio in men aged <65 years was 2.06 (95% confidence interval, 1.32–3.20). Only 0.9% of the arterial events were attributed to VTE, and the VTE explained 63.8% of the risk of arterial events among VTE patients.

Conclusions—

Our findings imply that women and young men with VTE have higher risk of arterial thrombotic disease than those without VTE. However, only 1% of the arterial thrombotic events in the population are attributed to VTE.

The realm of vitamin K dependent proteins: shifting from coagulation toward calcification

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.

Vitamin K status in healthy volunteers

Vitamin K's recommended dietary allowance (RDA) is based on the hepatic requirement for clotting factor synthesis, but substantial concentrations of undercarboxylated extra-hepatic Gla-proteins are found in the circulation of non-supplemented individuals. This suggests that vitamin K intake above the RDA is required for an optimal extra-hepatic vitamin K status. Circulating uncarboxylated osteocalcin (ucOC) and desphospho-uncarboxylated matrix Gla-protein (dp-ucMGP) are considered markers of the vitamin K status in bone and the vasculature, respectively. We measured these markers in 896 samples of healthy volunteers and defined target groups for vitamin K supplementation based on increased levels indicative of tissue-specific vitamin K deficiency. We studied the response to vitamin K supplements at different states of vitamin K deficiency by measuring the circulating dp-ucMGP level in samples from two short-term trials on menaquinone-7 (MK-7, vitamin K2) supplementation in 42 children and 68 adults. Children had high ucOC levels (3.4-96.9 ng ml(-1)); other age groups had values in the range of 1.5-5.0 ng ml(-1). From the age of 40 years, dp-ucMGP levels gradually increased. Children and adults with more pronounced vitamin K deficiency gave the highest responses to MK-7 supplementation. Children and adults above 40 years showed the largest tissue-specific vitamin deficiency and accordingly may benefit from MK-7 supplementation to improve their extra-hepatic vitamin K status.

Intake of dietary phylloquinone and menaquinones and risk of stroke

Background

Dietary vitamin K intake is thought to decrease the risk of cardiovascular disease (CVD) by reducing vascular calcification, although vitamin K is also involved in coagulation. Studies investigating the association between phylloquinone intake and risk of stroke are scarce, and the relation with menaquinones has not been investigated to date.

Methods and Results

We investigated the association between intake of phylloquinone and menaquinones and stroke in a prospective cohort of 35 476 healthy subjects. Information on occurrence of stroke was obtained by linkage to national registries, and stroke was further specified into ischemic and hemorrhagic stroke. Vitamin K intake was estimated using a validated food‐frequency questionnaire. Multivariate Cox proportional hazards models adjusted for cardiovascular risk factors, lifestyle, and other dietary factors were used to estimate the associations. During a follow‐up of 12.1±2.1 years, 580 incident cases of stroke were identified, 163 of which were hemorrhagic and 324 were ischemic. Phylloquinone intake was not associated with risk of stroke with a hazard ratio (HR) of 1.09 (95% CI: 0.85 to 1.40, P_trend 0.41) for the highest versus lowest quartile. For intake of menaquinones similar results were found, with an HR_{Q4 versus Q1} of 0.99 (95% CI: 0.75 to 1.29, P_trend 0.82). When specifying hemorrhagic and ischemic stroke or menaquinone subtypes, no significant associations were detected.

Conclusion

In our study, neither dietary phylloquinone nor dietary menaquinones intake were associated with stroke risk.

Matrix Gla protein species and risk of cardiovascular events in type 2 diabetic patients

OBJECTIVE

To investigate the relationship of circulating matrix Gla protein (MGP) species with incident cardiovascular disease (CVD) or coronary heart disease (CHD) in type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

EPIC-NL is a prospective cohort study among 40,011 Dutch men and women. At baseline (1993-1997), 518 participants were known to have type 2 diabetes. MGP levels were measured by ELISA techniques in baseline plasma samples. The incidence of fatal and nonfatal CVD and CVD subtypes-CHD, peripheral arterial disease (PAD), heart failure, and stroke-were obtained by linkage to national registers. Cox proportional hazard models were used to calculate hazard ratios (HRs), adjusted for sex, waist-to-hip ratio, physical activity, and history of CVD.

RESULTS

During a median 11.2 years of follow-up, 160 cases of CVD were documented. Higher circulating desphospho-uncarboxylated MGP (dp-ucMGP) levels were significantly associated with higher risk of CVD, with an HR per SD (HRSD) of 1.21 (95% CI 1.06-1.38), PAD (HRSD 1.32 [95% CI 1.07-1.65]), and heart failure (HRSD 1.75 [95% CI 1.42-2.17]) after adjustment. Higher circulating dp-ucMGP levels were not related to risk of CHD (HRSD 1.12 [95% CI 0.94-1.34]) or stroke (HRSD 1.05 [95% CI 0.73-1.49]). Circulating desphospho-carboxylated MGP and circulating total-uncarboxylated MGP levels were not associated with CVD or CVD subtypes.

CONCLUSIONS

High dp-ucMGP levels were associated with increased CVD risk among type 2 diabetic patients, especially with the subtypes PAD and heart failure, while other MGP species were not related to CVD risk. These results suggest that a poor vitamin K status is associated with increased CVD risk.

Association of functional VKORC1 promoter polymorphism with occurrence and clinical aspects of ischemic stroke in a Greek population

Genetic factors are considered to play an important role in determining the susceptibility to the occurrence, clinical course, and functional outcome of an acute ischemic stroke (IS). Undercarboxylation of specific vitamin K-dependent proteins, due to genetic polymorphisms of VKORC1, can affect both vascular calcification and thrombogenicity. We sought to determine the association of VKORC1 −1639G > A polymorphism with IS incidence, age of onset, severity of disease, and functional outcome after an acute IS. VKORC1 −1639G > A polymorphism was determined in 145 consecutive patients with first ever IS and 145 age- and sex-matched control subjects of Greek Caucasian origin using PCR-RFLP. Stroke severity and functional outcome were assessed on admission and at one month after stroke, respectively. Frequency of VKORC1 −1639G > A genotypes did not differ between IS patients and controls (OR = 1.12, P = 0.51). Moreover, carriage of the A allele was not associated with age of stroke onset, severity of disease (Scandinavian stroke scale score 32.2 versus 32.9, resp., P = 0.96), or poor outcome at 1 month post-stroke (52.9 versus 64.4%, resp., P = 0.31). In conclusion, VKORC1 −1639G > A polymorphism is not a genetic determinant of IS occurrence, age of onset, severity, or functional outcome of disease in a Greek population.

Warfarin accelerates ectopic mineralization in Abcc6(-/-) mice: clinical relevance to pseudoxanthoma elasticum

Pseudoxanthoma elasticum (PXE) is a multisystem ectopic mineralization disorder caused by mutations in the ABCC6 gene. Warfarin, a commonly used anticoagulant, is associated with increased mineralization of the arterial blood vessels and cardiac valves. We hypothesized that warfarin may accelerate ectopic tissue mineralization in PXE, with clinical consequences. To test this hypothesis, we developed a model in which Abcc6(-/-) mice, which recapitulate features of PXE, were fed a diet supplemented with warfarin and vitamin K1. Warfarin action was confirmed by significantly increased serum levels of oxidized vitamin K. For mice placed on a warfarin-containing diet, quantitative chemical and morphometric analyses revealed massive accumulation of mineral deposits in a number of tissues. Mice fed a warfarin-containing diet were also shown to have abundant uncarboxylated form of matrix Gla protein, which allowed progressive tissue mineralization to ensue. To explore the clinical relevance of these findings, 1747 patients with PXE from the approximately 4000 patients in the PXE International database were surveyed about the use of warfarin. Of the 539 respondents, 2.6% reported past or present use of warfarin. Based on the prevalence of PXE (approximately 1:50,000), thousands of patients with PXE worldwide may be at risk for worsening of PXE as a result of warfarin therapy.

Quercetin attenuates warfarin-induced vascular calcification in vitro independently from matrix Gla protein

Warfarin can stimulate vascular calcification in vitro via activation of β-catenin signaling and/or inhibition of matrix Gla protein (MGP) carboxylation. Calcification was induced in vascular smooth muscle cells (VSMCs) with therapeutic levels of warfarin in normal calcium and clinically acceptable phosphate levels. Although TGF/BMP and PKA pathways are activated in calcifying VSMCs, pharmacologic analysis reveals that their activation is not contributory. However, β-catenin activity is important because inhibition of β-catenin with shRNA or bioflavonoid quercetin prevents calcification in primary human VSMCs, rodent aortic rings, and rat A10 VSMC line. In the presence of quercetin, reactivation of β-catenin using the glycogen synthase kinase-3β (GSK-3β) inhibitor LiCl restores calcium accumulation, confirming that quercetin mechanism of action hinges on inhibition of the β-catenin pathway. Calcification in VSMCs induced by 10 μm warfarin does not associate with reduced levels of carboxylated MGP, and inhibitory effects of quercetin do not involve induction of MGP carboxylation. Further, down-regulation of MGP by shRNA does not alter the effect of quercetin. These results suggest a new β-catenin-targeting strategy to prevent vascular calcification induced by warfarin and identify quercetin as a potential therapeutic in this pathology.

Mechanisms of arterial remodeling: lessons from genetic diseases

Vascular disease is still the leading cause of morbidity and mortality in the Western world, and the primary cause of myocardial infarction, stroke, and ischemia. The biology of vascular disease is complex and still poorly understood in terms of causes and consequences. Vascular function is determined by structural and functional properties of the arterial vascular wall. Arterial stiffness, that is a pathological alteration of the vascular wall, ultimately results in target-organ damage and increased mortality. Arterial remodeling is accelerated under conditions that adversely affect the balance between arterial function and structure such as hypertension, atherosclerosis, diabetes mellitus, chronic kidney disease, inflammatory disease, lifestyle aspects (smoking), drugs (vitamin K antagonists), and genetic abnormalities [e.g., pseudoxanthoma elasticum (PXE), Marfan's disease]. The aim of this review is to provide an overview of the complex mechanisms and different factors that underlie arterial remodeling, learning from single gene defect diseases like PXE, and PXE-like, Marfan's disease and Keutel syndrome in vascular remodeling.

Vitamin K-antagonists accelerate atherosclerotic calcification and induce a vulnerable plaque phenotype

BACKGROUND

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.

METHODOLOGY/PRINCIPAL FINDINGS

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.

CONCLUSIONS/SIGNIFICANCE

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.

Calcium scoring in patients with a history of Kawasaki disease

OBJECTIVES

The goal of this study was to assess coronary artery calcification in patients ≥10 years or age with a history of Kawasaki disease (KD).

BACKGROUND

Patients with a history of KD and coronary artery aneurysms are at risk for late morbidity from coronary artery events. It is unknown whether patients with KD with acutely normal or transiently dilated coronary arteries also have increased risk of late coronary artery complications. Coronary calcium scoring using noncontrast computed tomography is a well-established tool for risk-stratifying patients with atherosclerotic coronary artery disease, but there are limited data on its role in evaluating patients with a history of KD.

METHODS

We performed coronary artery calcium (CAC) volume scoring using a low radiation dose computed tomography protocol on 70 patients (median age 20.0 years) with a remote history of KD (median interval from acute KD to imaging 14.8 years). Forty-four (63%) patients had no history of coronary dilation, 12 (17%) had a history of transient dilation, and 14 (20%) had coronary aneurysms.

RESULTS

All of the patients with normal coronary artery internal diameter during the acute phase of KD and 11 of 12 patients with transient dilation had CAC scores of zero. Coronary calcification was observed in 10 of the 14 patients with coronary aneurysms, with the degree of calcification ranging from mild to severe and occurring years after the patients' acute KD.

CONCLUSIONS

Coronary calcification was not observed in patients with a history of KD and normal coronary arteries during the acute phase. Therefore, CAC scanning may be a useful tool to screen patients with a remote history of KD or suspected KD and unknown coronary artery status. Coronary calcification, which may be severe, occurs late in patients with coronary aneurysms. The pathophysiology and clinical implications of coronary calcification in patients with aneurysms are currently unknown and warrant further study.

The impact of blood coagulability on atherosclerosis and cardiovascular disease

Although the link between blood coagulation and atherogenesis has been long postulated, only recently, and through the extensive work on transgenic mice, crossbred on an atherogenic background, has the direction of this interaction become visible. In general, hypercoagulability in mice tends to increase atherosclerosis, whereas hypocoagulability reduces the atherosclerotic burden, depending on the mouse model used. The information on a direct relationship between coagulation and atherosclerosis in humans, however, is not that clear. Almost all coagulation proteins, including tissue factor, are found in atherosclerotic lesions in humans. In addition to producing local fibrin, a matrix for cell growth, serine proteases such as thrombin may be very important in cell signaling processes, acting through the activation of protease-activated receptors (PARs). Activation of PARs on vascular cells drives many complex processes involved in the development and progression of atherosclerosis, including inflammation, angiogenesis, and cell proliferation. Although current imaging techniques do not allow for a detailed analysis of atherosclerotic lesion phenotype, hypercoagulability, defined either by gene defects of coagulation proteins or elevated levels of circulating markers of activated coagulation, has been linked to atherosclerosis-related ischemic arterial disease. New, high-resolution imaging techniques and sensitive markers of activated coagulation are needed in order to study a causal contribution of hypercoagulability to the pathophysiology of atherosclerosis. Novel selective inhibitors of coagulation enzymes potentially have vascular effects, including inhibition of atherogenesis through attenuation of inflammatory pathways. Therefore, we propose that studying the long-term vascular side effects of this novel class of oral anticoagulants should become a clinical research priority.

Vascular calcification: the price to pay for anticoagulation therapy with vitamin K-antagonists

Vitamin K-antagonists (VKA) are the most widely used anti-thrombotic drugs with substantial efficacy in reducing risk of arterial and venous thrombosis. Several lines of evidence indicate, however, that VKA inhibit not only post-translational activation of vitamin K-dependent coagulation factors but also synthesis of functional extra-hepatic vitamin K-dependent proteins thereby eliciting undesired side-effects. Vascular calcification is one of the recently revealed side-effects of VKA. Vascular calcification is an actively regulated process involving vascular cells and a number of vitamin K-dependent proteins. Mechanistic understanding of vascular calcification is essential to improve VKA-based treatments of both thrombotic disorders and atherosclerosis. This review addresses vitamin K-cycle and vitamin K-dependent processes of vascular calcification that are affected by VKA. We conclude that there is a growing need for better understanding of the effects of anticoagulants on vascular calcification and atherosclerosis.

Vitamin K status and vascular calcification: evidence from observational and clinical studies

Vascular calcification occurs when calcium accumulates in the intima (associated with atherosclerosis) and/or media layers of the vessel wall. Coronary artery calcification (CAC) reflects the calcium burden within the intima and media of the coronary arteries. In population-based studies, CAC independently predicts cardiovascular disease (CVD) and mortality. A preventive role for vitamin K in vascular calcification has been proposed based on its role in activating matrix Gla protein (MGP), a calcification inhibitor that is expressed in vascular tissue. Although animal and in vitro data support this role of vitamin K, overall data from human studies are inconsistent. The majority of population-based studies have relied on vitamin K intake to measure status. Phylloquinone is the primary dietary form of vitamin K and available supplementation trials, albeit limited, suggest phylloquinone supplementation is relevant to CAC. Yet observational studies have found higher dietary menaquinone, but not phylloquinone, to be associated with less calcification. Vascular calcification is highly prevalent in certain patient populations, especially in those with chronic kidney disease (CKD), and it is plausible vitamin K may contribute to reducing vascular calcification in patients at higher risk. Subclinical vitamin K deficiency has been reported in CKD patients, but studies linking vitamin K status to calcification outcomes in CKD are needed to clarify whether or not improving vitamin K status is associated with improved vascular health in CKD. This review summarizes the available evidence of vitamin K and vascular calcification in population-based studies and clinic-based studies, with a specific focus on CKD patients.

The role of vitamin K in soft-tissue calcification

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.

Patients using vitamin K antagonists show increased levels of coronary calcification: an observational study in low-risk atrial fibrillation patients

AIMS

Vitamin K antagonists (VKA) are currently the most frequently used drug to prevent ischaemic stroke in atrial fibrillation (AF) patients. However, VKA use has been associated with increased vascular calcification. The aim of this study was to investigate the contribution of VKA use to coronary artery calcification in low-risk AF patients.

METHODS AND RESULTS

A prospective coronary calcium scan was performed in 157 AF patients without significant cardiovascular disease (108 males; mean age 57 ± 9 years). A total of 71 (45%) patients were chronic VKA users. The duration of VKA treatment varied between 6 and 143 months (mean 46 months). No significant differences in clinical characteristics were found between patients on VKA treatment and non-anticoagulated patients. However, median coronary artery calcium scores differed significantly between patients without and patients with VKA treatment [0, inter-quartile range (IQR) 0-40, vs. 29, IQR 0-184; P = 0.001]. Mean coronary calcium scores increased with the duration of VKA use (no VKA: 53 ± 115, 6-60 months on VKA: 90 ± 167, and >60 months on VKA: 236 ± 278; P < 0.001). Multivariable logistic regression analysis revealed that age and VKA treatment were significantly related to increased coronary calcium score.

CONCLUSION

Patients using VKA show increased levels of coronary calcification. Age and VKA treatment were independently related to increased coronary calcium score.

Role of vitamin K-dependent proteins in the arterial vessel wall

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.

[Calciphylaxis. A less well-known, clinically relevant disease]

Calciphylaxis is a rare disease which has been increasingly reported in recent decades and has consequently shifted into the focus of clinical and scientific research. The clinical picture is characterized by extensive ischemic ulcerations of the skin and subcutis. Histologically, the small vessels in these lesions show prominent calcifications. Due to the extensive areas of ulceration and necrosis as well as frequently present comorbidities, patients with calciphylaxis are prone to infection and sepsis. In this work, we describe the case of a female kidney-transplant patient with vasculitis who, despite good graft function, developed a fulminant calciphylaxis of both thighs 4 years post transplantation and died of septic complications. The differential diagnoses as well as clinical procedures are described in detail in the case history. In the discussion, we give an overview of the current state of knowledge regarding the etiopathogenesis, risk factors, diagnostic measures and clinical management of calciphylaxis.

Prevention of mutation, cancer, and other age-associated diseases by optimizing micronutrient intake

I review three of our research efforts which suggest that optimizing micronutrient intake will in turn optimize metabolism, resulting in decreased DNA damage and less cancer as well as other degenerative diseases of aging. (1) Research on delay of the mitochondrial decay of aging, including release of mutagenic oxidants, by supplementing rats with lipoic acid and acetyl carnitine. (2) The triage theory, which posits that modest micronutrient deficiencies (common in much of the population) accelerate molecular aging, including DNA damage, mitochondrial decay, and supportive evidence for the theory, including an in-depth analysis of vitamin K that suggests the importance of achieving optimal micronutrient intake for longevity. (3) The finding that decreased enzyme binding constants (increased Km) for coenzymes (or substrates) can result from protein deformation and loss of function due to an age-related decline in membrane fluidity, or to polymorphisms or mutation. The loss of enzyme function can be compensated by a high dietary intake of any of the B vitamins, which increases the level of the vitamin-derived coenzyme. This dietary remediation illustrates the importance of understanding the effects of age and polymorphisms on optimal micronutrient requirements. Optimizing micronutrient intake could have a major effect on the prevention of cancer and other degenerative diseases of aging.