Vitamin K for Vascular Calcification in Kidney Patients: Still Alive and Kicking, but Still a Lot to Learn.

Patients with chronic kidney disease (CKD) suffer disproportionately from a high burden of cardiovascular disease, which, despite recent scientific advances, remains partly understood. Vascular calcification (VC) is the result of an ongoing process of misplaced calcium in the inner and medial layers of the arteries, which has emerged as a critical contributor to cardiovascular events in CKD. Beyond its established role in blood clotting and bone health, vitamin K appears crucial in regulating VC via vitamin K-dependent proteins (VKDPs). Among these, the matrix Gla protein (MGP) serves as both a potent inhibitor of VC and a valuable biomarker (in its inactive form) for reflecting circulating vitamin K levels. CKD patients, especially in advanced stages, often present with vitamin K deficiency due to dietary restrictions, medications, and impaired intestinal absorption in the uremic environment. Epidemiological studies confirm a strong association between vitamin K levels, inactive MGP, and increased CVD risk across CKD stages. Based on the promising results of pre-clinical data, an increasing number of clinical trials have investigated the potential benefits of vitamin K supplementation to prevent, delay, or even reverse VC, but the results have remained inconsistent.

Vitamin K2 Supplementation in Hospitalised COVID-19 Patients: A Randomised Controlled Trial.

Background: In observational studies, high levels of desphospho-uncarboxylated matrix gla protein (dp-ucMGP) that result from vitamin K deficiency were consistently associated with poor clinical outcomes during COVID-19. Vitamin K-activated matrix gla protein (MGP) is required to protect against elastic fibre degradation, and a deficiency may contribute to pathology. However, intervention trials assessing the effects of vitamin K supplementation in COVID-19 are lacking. Methods: This is a single-centre, phase 2, double-blind, randomised, placebo-controlled trial investigating the effects of vitamin K2 supplementation in 40 hospitalised COVID-19 patients requiring supplemental oxygen. Individuals were randomly assigned in a 1:1 ratio to receive 999 mcg of vitamin K2-menaquinone-7 (MK-7)-or a placebo daily until discharge or for a maximum of 14 days. Dp-ucMGP, the rate of elastic fibre degradation quantified by desmosine, and hepatic vitamin K status quantified by PIVKA-II were measured. Grade 3 and 4 adverse events were collected daily. As an exploratory objective, circulating vitamin K2 levels were measured. Results: Vitamin K2 was well tolerated and did not increase the number of adverse events. A linear mixed model analysis showed that dp-ucMGP and PIVKA-II decreased significantly in subjects that received supplementation compared to the controls (p = 0.008 and p = 0.0017, respectively), reflecting improved vitamin K status. The decrease in dp-ucMGP correlated with higher plasma MK-7 levels (p = 0.015). No significant effect on desmosine was found (p = 0.545). Conclusions: These results demonstrate that vitamin K2 supplementation during COVID-19 is safe and decreases dp-ucMGP. However, the current dose of vitamin K2 failed to show a protective effect against elastic fibre degradation.

Matrix gla protein, a potential marker of tissue remodelling and physiological ageing of the gut in crohn's disease.

BACKGROUND: The inactive dephosphorylated and uncarboxylated form of the matrix Gla protein (dp-ucMGP) has been shown to be increased in plasma of inflammatory bowel disease (IBD) patients. Our aim was to assess if the plasmatic level of dp-ucMGP could reflect disease endoscopic activity, presence of strictures and cumulative structural bowel damage in Crohn's disease (CD) patients. METHODS: The plasmatic level of dp-ucMGP was measured in a monocentric cohort of prospectively recruited patients. The analysis was done by chemiluminescent immunoassay on blood samples collected the day of a planned ileocolonoscopy. In addition to classical clinical data (gender, age, body mass index (BMI), disease duration, current treatment), endoscopic data (disease location, Crohn's Disease Endoscopic Index of Severity (CDEIS), mucosal healing (MH), presence of 9 CD lesion types) and biological markers (faecal calprotectin and C-reactive protein (CRP)) were collected. The association between dp-ucMGP level and Lémann index was also investigated. Univariate linear regression was used to investigate the relationship between dp-ucMGP level and different parameters collected. RESULTS: A total of 82 ileocolonoscopies and dp-ucMGP assays were performed in 75 CD patients (45 females; 37 ileocolonic, 19 ileal and 19 colonic diseases) between October 2012 and November 2019. A total of 24 patients (29.3%) showed MH. The dp-ucMGP levels were not associated with MH, CDEIS, faecal calprotectin or CRP levels. Plasmatic dp-ucMGP levels increased significantly with age (p = 0.0032), disease duration (p = 0.0033), corticosteroids use (p = 0.019) and tended to increase in patients with intestinal strictures (p = 0.086) but not with the Lémann index. CONCLUSION: The significant increase of plasmatic dp-ucMGP levels with age, disease duration and the trend observed in patients with non-ulcerated strictures may suggest that this extracellular matrix protein could be a marker of tissue remodelling and physiological ageing of the gut.

Dp-ucMGP as a Biomarker in Sarcopenia.

Sarcopenia is linked with an increased risk of falls, osteoporosis and mortality and is an increasing problem for healthcare systems. No satisfying biomarkers for sarcopenia diagnosis exist, connecting bone, fat and muscle. Matrix-GLA-protein (MGP) is an adipokine that regulates bone metabolism and is associated with decreased muscle strength. Associations of dp-ucMGP were analyzed in the BioPersMed cohort (58 ± 9 years), including 1022 asymptomatic subjects at moderate cardiovascular risk. Serum measurements of dp-ucMGP in 760 persons were performed with the InaKtif MGP Kit with the IDS-iSYS Multi-Discipline Automated System. DXA data (792 persons) measured with the Lunar iDXA system and physical performance data (786 persons) were available. Dp-ucMGP plasma levels correlate with sarcopenia parameters like gait speed (ρ = −0.192, p < 0.001), appendicular skeletal muscle mass (ρ = 0.102, p = 0.005) and appendicular skeletal muscle mass index (ρ = 0.112, p = 0.001). They are lower in persons with sarcopenia (p < 0.001) and higher in persons with reduced physical performance (p = 0.019). Persons in the lowest dp-ucMGP quartile have the highest risk for reduced muscle mass, decreasing with each quartile, whereas persons in the highest quartile have the highest risk of reduced muscle strength. Dp-ucMGP might be a good biomarker candidate in sarcopenia characterization.

Enhanced vitamin K expenditure as a major contributor to vitamin K deficiency in COVID-19.

OBJECTIVES: Vitamin K deficiency consistently associates with worse clinical outcome in COVID-19 patients. However, whether this is due to increased expenditure during inflammation or poor vitamin K status prior to infection remained unknown. METHODS: Dp-ucMGP levels of 128 individuals were measured for the post-MONICA study and were compared to SARS-CoV-2 PCR testing results. RESULTS: Dp-ucMGP levels prior to COVID-19 infection were not significantly different comparing PCR-negative, PCR-positive and not hospitalized, and PCR-positive and hospitalized patients. CONCLUSION: In this study, we demonstrate normal vitamin K status prior to infection in SARS-CoV-2 positive patients, supporting the theory of increased utilisation during disease.

Serum biomarkers for arterial calcification in humans: A systematic review.

Aim: To clarify the role of mediators of ectopic mineralization as biomarkers for arterial calcifications. Methods: MEDLINE and Embase were searched for relevant literature, until January 4th 2022. The investigated biomarkers were: calcium, phosphate, parathyroid hormone, vitamin D, pyrophosphate, osteoprotegerin, receptor activator of nuclear factor-kappa B ligand (RANKL), fibroblast growth factor-23 (FGF-23), Klotho, osteopontin, osteocalcin, Matrix Gla protein (MGP) and its inactive forms and vitamin K. Studies solely performed in patients with kidney insufficiency or diabetes mellitus were excluded. Results: After screening of 8985 articles, a total of 129 articles were included in this systematic review. For all biomarkers included in this review, the results were variable and more than half of the studies for each specific biomarker had a non-significant result. Also, the overall quality of the included studies was low, partly as a result of the mostly cross-sectional study designs. The largest body of evidence is available for phosphate, osteopontin and FGF-23, as a little over half of the studies showed a significant, positive association. Firm statements for these biomarkers cannot be drawn, as the number of studies was limited and hampered by residual confounding or had non-significant results. The associations of the other mediators of ectopic mineralization with arterial calcifications were not clear. Conclusion: Associations between biomarkers of ectopic mineralization and arterial calcification are variable in the published literature. Future longitudinal studies differentiating medial and intimal calcification could add to the knowledge of biomarkers and mechanisms of arterial calcifications.

Corrigendum: Effects of Vitamin D and K on Interleukin-6 in COVID-19.

[This corrects the article DOI: 10.3389/fnut.2021.761191.].

Low vitamin K status, high sclerostin and mortality risk of stable coronary heart disease patients.

Aim: We explored whether matrix Gla protein (MGP, natural calcification inhibitor) and sclerostin (glycoprotein responsible for osteoblast differentiation) interact in terms of mortality risk in coronary patients. Methods: 945 patients after myocardial infarction and/or coronary revascularization were followed in a prospective study. All-cause death, fatal or nonfatal cardiovascular events and heart failure hospitalizations were registered. Results: Either high desphospho-uncarboxylated MGP (dp-ucMGP) or high sclerostin were independently associated with 5-year all-cause/cardiovascular mortality. However, we observed an additional mortality risk in the coincidence of both factors. Concomitantly high dp-ucMGP (≥884 pmol/l) plus sclerostin (≥589 ng/l) were associated with increased all-cause mortality risk compared with 'normal' concentrations of both factors (HRR 3.71 [95% CI: 2.07-6.62, p < 0.0001]), or if only one biomarker has been increased. A similar pattern was observed for fatal, but not for nonfatal cardiovascular events. Conclusion: Concomitantly high MGP and sclerostin indicate increased mortality risk, which probably reflects their role in cardiovascular calcifications.

Hepatic and Vascular Vitamin K Status in Patients with High Cardiovascular Risk.

Vitamin K dependent proteins (VKDP), such as hepatic coagulation factors and vascular matrix Gla protein (MGP), play key roles in maintaining physiological functions. Vitamin K deficiency results in inactive VKDP and is strongly linked to vascular calcification (VC), one of the major risk factors for cardiovascular morbidity and mortality. In this study we investigated how two vitamin K surrogate markers, dephosphorylated-undercarboxylated MGP (dp-ucMGP) and protein induced by vitamin K absence II (PIVKA-II), reflect vitamin K status in patients on hemodialysis or with calcific uremic arteriolopathy (CUA) and patients with atrial fibrillation or aortic valve stenosis. Through inter- and intra-cohort comparisons, we assessed the influence of vitamin K antagonist (VKA) use, vitamin K supplementation and disease etiology on vitamin K status, as well as the correlation between both markers. Overall, VKA therapy was associated with 8.5-fold higher PIVKA-II (0.25 to 2.03 AU/mL) and 3-fold higher dp-ucMGP (843 to 2642 pM) levels. In the absence of VKA use, non-renal patients with established VC have dp-ucMGP levels similar to controls (460 vs. 380 pM), while in HD and CUA patients, levels were strongly elevated (977 pM). Vitamin K supplementation significantly reduced dp-ucMGP levels within 12 months (440 to 221 pM). Overall, PIVKA-II and dp-ucMGP showed only weak correlation (r2 ≤ 0.26) and distinct distribution pattern in renal and non-renal patients. In conclusion, VKA use exacerbated vitamin K deficiency across all etiologies, while vitamin K supplementation resulted in a vascular VKDP status better than that of the general population. Weak correlation of vitamin K biomarkers calls for thoughtful selection lead by the research question. Vitamin K status in non-renal deficient patients was not anomalous and may question the role of vitamin K deficiency in the pathogenesis of VC in these patients.

Intravenous Vitamin K1 for the Correction of Prolonged Prothrombin Times in Non-Bleeding Critically Ill Patients: A Prospective Observational Study.

The aim of this study was to evaluate the effects of vitamin K1 on various vitamin K-dependent proteins in critically ill patients with prolonged Owren PT. We included critically ill non-bleeding adult patients without liver failure or anticoagulation treatment, with Owren PT > 1.2, who were prescribed intravenous vitamin K1. Blood was drawn at baseline and at 20-28 h after vitamin K1 administration. At both time points, we measured various vitamin K-dependent proteins and coagulation assays. ClinicalTrials.gov; Identifier: NTC3782025. In total, 52 patients were included. Intravenous vitamin K1 reduced Owren PT, Quick PT, protein induced by vitamin K absence/antagonist-II and desphospho-uncarboxylated matrix Gla protein (dp-ucMGP), but not to normal levels. Concomitantly, there were increases in thrombin generation and the activity of coagulation factors II, VII, IX and X that was only counteracted with a small increase in Protein C activity. In conclusion, the results suggest that vitamin K1 strengthens coagulation as measured by PT decrease and increases in the activity of vitamin K-dependent clotting factors and thrombin generation. The decreased dp-ucMGP, and its potential positive short- and long-term non-coagulative effects, merits further research.

The coincidence of low vitamin K status and high expression of growth differentiation factor 15 may indicate increased mortality risk in stable coronary heart disease patients.

BACKGROUND AND AIMS: Matrix Gla protein (MGP) is a natural inhibitor of vascular calcification critically dependent on circulating vitamin K status. Growth differentiation factor 15 (GDF-15) is a regulatory cytokine mainly of the inflammatory and angiogenesis pathways, but potentially also involved in bone mineralization. We sought to determine whether these two circulating biomarkers jointly influenced morbidity and mortality risk in patients with chronic coronary heart disease (CHD). METHODS AND RESULTS: 894 patients ≥6 months after myocardial infarction and/or coronary revascularization at baseline were followed in a prospective study. All-cause and cardiovascular mortality, non-fatal cardiovascular events (myocardial infarction, stroke, any revascularization), and hospitalization for heart failure (HF) were followed as outcomes. Desphospho-uncarboxylated MGP (dp-ucMGP) was used as a biomarker of vitamin K status. Both, increased concentrations of dp-ucMGP (≥884 pmol/L) and GDF-15 (≥1339 pg/mL) were identified as independent predictors of 5-year all-cause or cardiovascular mortality. However, their coincidence further increased mortality risk. The highest risk was observed in patients with high dp-ucMGP plus high GDF-15, not only when compared with those with "normal" concentrations of both biomarkers [HR 5.51 (95% CI 2.91-10.44), p < 0.0001 and 6.79 (95% CI 3.06-15.08), p < 0.0001 for all-cause and cardiovascular mortality, respectively], but even when compared with patients with only one factor increased. This pattern was less convincing with non-fatal cardiovascular events or hospitalization for HF. CONCLUSIONS: The individual coincidence of low vitamin K status (high dp-ucMGP) and high GDF-15 expression predicts poor survival of stable CHD patients.

Effects of Vitamin D and K on Interleukin-6 in COVID-19.

BACKGROUND: Pathology during COVID-19 infection arises partly from an excessive inflammatory response with a key role for interleukin (IL)-6. Both vitamin D and K have been proposed as potential modulators of this process. METHODS: We assessed vitamin D and K status by measuring circulating 25-hydroxyvitamin D (25(OH)D) and desphospho-uncarboxylated Matrix Gla-Protein (dp-ucMGP), respectively in 135 hospitalized COVID-19 patients in relation to inflammatory response, elastic fiber degradation and clinical outcomes. RESULTS: Comparing good and poor disease outcomes of COVID-19 patients, vitamin 25(OH)D levels were not significantly different. IL-6 levels, however, were significantly higher in patients with poor outcome, compared to patients with good outcome (30.3 vs. 153.0 pg/mL; p < 0.0001). Dp-ucMGP levels as biomarker of extrahepatic vitamin K status was associated with IL-6 levels (r = 0.35; p < 0.0001). In contrast, 25(OH)D levels were only borderline statistically significant correlated with IL-6 (r = -0.14; p <0.050). A significant association was also found between IL-6 and elastic fiber degradation. Contrary to vitamin K status, 25(OH)D did not correlate with elastic fiber degradation. CONCLUSIONS: Dp-ucMGP associates with IL-6 as a central component of the destructive inflammatory processes in COVID-19. An intervention trial may provide insight whether vitamin K administration, either or not in combination with vitamin D, improves clinical outcome of COVID-19.

The Association of Vitamin D and Vitamin K Status with Subclinical Measures of Cardiovascular Health and All-Cause Mortality in Older Adults: The Hoorn Study.

BACKGROUND: A low vitamin D and K status has been associated with increased cardiovascular disease (CVD) risk but the evidence of their combined effect on cardiovascular health is limited. OBJECTIVES: Our study aimed to investigate the prospective association of vitamin D and K status with subclinical measures of cardiovascular health and all-cause mortality among a population of Dutch Caucasians. METHODS: We performed an observational prospective study on 601 participants of the Hoorn Study (mean ± SD age: 70 ± 6 y, 50.4% women, BMI: 27.2 ± 4.0 kg/m2), of whom 321 underwent an echocardiogram in 2000-2001 and 2007-2009. Vitamin D and K status was assessed at baseline by serum 25-hydroxyvitamin D [25(OH)D] and plasma desphospho-uncarboxylated matrix-gla protein (dp-ucMGP)-high concentrations indicate low vitamin K status. Vital status was assessed from baseline until 2018. We studied the association of categories of 25(OH)D (stratified by the clinical cutoff of 50 mmol/L) and dp-ucMGP (stratified by the median value of 568 pmol/L) with echocardiographic measures using linear regression and with all-cause mortality using Cox regression, adjusted for confounders. RESULTS: Compared with markers of normal vitamin D and K status, markers of low vitamin D and K status were prospectively associated with increased left ventricular mass index (5.9 g/m2.7; 95% CI: 1.8, 10.0 g/m2.7). Participants with low vitamin D and K status were also at increased risk of all-cause mortality with an HR of 1.64 (95% CI: 1.12, 2.39) compared with normal vitamin D and K status. CONCLUSIONS: A combination of low vitamin D and K status is associated with adverse cardiac remodeling and increased risk of all-cause mortality in men and women. Future studies should investigate whether vitamin D and K supplementation could help to improve cardiovascular health and to decrease CVD risk.

Causes of Vitamin K Deficiency in Patients on Haemodialysis.

Background: A low vitamin K status is common in patients on haemodialysis, and this is considered one of the reasons for the accelerated atherosclerosis in these patients. The vitamin is essential in activation of the protein Matrix Gla Protein (MGP), and the inactive form, dp-ucMGP, is used to measure vitamin K status. The purpose of this study was to investigate possible underlying causes of low vitamin K status, which could potentially be low intake, washout during dialysis or inhibited absorption capacity. Moreover, the aim was to investigate whether the biomarker dp-ucMGP is affected in these patients. Method: Vitamin K intake was assessed by a Food Frequency Questionnaire (FFQ) and absorption capacity by means of D-xylose testing. dp-ucMGP was measured in plasma before and after dialysis, and phylloquinine (vitamin K1) and dp-ucMGP were measured in the dialysate. Changes in dp-ucMGP were measured after 14 days of protein supplementation. Results: All patients had plasma dp-ucMGP above 750 pmol/L, and a low intake of vitamin K. The absorption capacity was normal. The difference in dp-ucMGP before and after dialysis was -1022 pmol/L (p < 0.001). Vitamin K1 was not present in the dialysate but dp-ucMGP was at a high concentration. The change in dp-ucMGP before and after protein supplementation was -165 pmol/L (p = 0.06). Conclusion: All patients had vitamin K deficiency. The reason for the low vitamin K status is not due to removal of vitamin K during dialysis or decreased absorption but is plausibly due to a low intake of vitamin K in food. dp-ucMGP is washed out during dialysis, but not affected by protein intake to a clinically relevant degree.

Uncarboxylated matrix Gla-protein: A biomarker of vitamin K status and cardiovascular risk.

BACKGROUND: Dephosphorylated uncarboxylated matrix Gla-protein (dp-ucMGP) is a biomarker of functional vitamin K status. High plasma dp-ucMGP concentrations reflect a low vitamin K status and have been related to vascular calcification. Our aims were to assess plasma levels of dp-ucMGP and their association with cardiovascular risk in a general population. METHODS: Plasma dp-ucMGP measurements were performed using the IDS-iSYS InaKtif MGP assay in 491 consecutive participants in a Danish general population study (229 males and 262 females, aged 19-71 years). Multivariable linear and logistic regressions were used to assess the association between dp-ucMGP levels and cardiovascular risk factors. RESULTS: Mean ± standard deviation (SD) for dp-ucMGP was 465 ± 181 pmol/L, and upper 95th percentile was 690 pmol/L. In logistic regression analyses, an increase in dp-ucMGP category (<300, 300-399, 400-499, ≥500 pmol/L) was positively associated with obesity, odds ratio (OR) 2.27 (95% confidence interval (CI) 1.54-3.33), history of cardiovascular disease, OR 1.77 (CI 1.02-3.05), and above-median estimated pulse wave velocity (ePWV), OR 1.54 (CI 1.21-1.96), when adjusted for age, sex, and lifestyle factors. 1 SD increase in diastolic and systolic blood pressure (BP) corresponded to a 5.5% (CI 2.9-8.0%) and 4.7% (CI 2.1-7.4%) increase in dp-ucMGP, respectively, when adjusted for age and sex. CONCLUSION: Plasma dp-ucMGP levels were positively associated with obesity, BP, ePWV, and history of cardiovascular disease. These findings support that dp-ucMGP is a biomarker of cardiovascular risk, and that vitamin K status could play a role in vascular calcification. The strong association with obesity deserves further attention.

Matrix Gla protein regulates adipogenesis and is serum marker of visceral adiposity.

Objective Matrix Gla protein (MGP) is a potent calcification inhibitor. Mgp-/- mice display increased proportion of brown adipose tissue. However, whether MGP is involved in fat metabolism remains unclear. This study aims to investigate the involvement. Methods Expression of adipocyte differentiation markers was examined by RT-qPCR. Adipocyte formation was assessed by Oil Red staining. Serum triglyceride, cholesterol, and desphosphorylated-uncarboxylated MGP (dp-ucMGP) were quantified by ELISA. Visceral fat was detected by bioelectrical impedance analysis. Results MGP is highly expressed in visceral fat. MGP expression is induced during preadipocyte differentiation. Knockout of MGP leads to retardation of 3T3-L1 differentiation. Intracellular triglyceride amount is impaired while glycerol release is increased in MGP-depleted cells. Serum dp-ucMGP level is significantly increased in individual with higher visceral fat index (VFI) and waist height ratio (WHtR), but not body mass index (BMI). Additionally, dp-ucMGP positively correlates to low-density lipoprotein cholesterol (LDL-C) level. Conclusions MGP is involved in fat metabolism and serum inactive MGP level is associated with visceral fat. Our study uncovers for the first time the link between MGP and fat metabolism, and sheds light on the potential of dp-ucMGP as a novel serum marker.

Association of vitamin K with cardiovascular events and all-cause mortality: a systematic review and meta-analysis.

PURPOSE: We conducted a meta-analysis to systematically assess the prospective association between vitamin K and cardiovascular disease (CVD) events and all-cause mortality. METHODS: We searched PubMed and EMBASE through January 2019 for prospective studies that reported the association of vitamin K (assessed by dietary intake or circulating concentration) with CVD events [including total CVD, CVD mortality, total coronary heart disease (CHD), fatal CHD, nonfatal myocardial infarction (MI), and stroke] and all-cause mortality. Multivariable-adjusted hazard ratios (HRs) comparing top versus bottom tertiles of vitamin K were combined using random-effects meta-analysis. RESULTS: Twenty-one articles were included with 222,592 participants. A significant association was found between dietary phylloquinone and total CHD (pooled HR 0.92; 95% CI 0.84, 0.99; I2 = 0%; four studies), as well as menaquinone and total CHD (0.70; 95% CI 0.53, 0.93; I2 = 32.1%; two studies). No significant association was observed between dietary vitamin K and all-cause mortality, CVD mortality, or stroke. Elevated plasma desphospho-uncarboxylated MGP (dp-ucMGP), a marker of vitamin K deficiency, was associated with an increased risk of all-cause mortality (1.84; 95% CI 1.48, 2.28; I2 = 16.8%; five studies) and CVD mortality (1.96; 95% CI 1.47, 2.61; I2 = 0%; two studies). No significant association was observed between circulating total osteocalcin and all-cause mortality or total CVD. CONCLUSIONS: Our findings showed that higher dietary vitamin K consumption was associated with a moderately lower risk of CHD, and higher plasma dp-ucMGP concentration, but not total circulating osteocalcin, was associated with increased risks of all-cause and CVD mortality. However, causal relations cannot be established because of limited number of available studies, and larger prospective studies and randomized clinical trials are needed to validate the findings.

Matrix Gla Protein, Plaque Stability, and Cardiovascular Events in Patients with Severe Atherosclerotic Disease.

OBJECTIVE: This study aims to investigate whether plasma matrix Gla protein (MGP) species, desphospho-uncarboxylated (dp-uc) MGP, and total uncarboxylated (t-uc) MGP are associated with plaque levels of uncarboxylated (uc) MGP, markers of plaque stability, and cardiovascular disease (CVD) risk. METHODS: From the Athero-Express biobank, we selected carotid plaque samples of 100 patients who underwent carotid endarterectomy. The level of agreement between plasma MGP species and plaque ucMGP levels was assessed using weighted kappa (κ). We analyzed histological characteristics of plaque composition (plaque hemorrhage, lipid and calcification content). Logistic regression analyses were used to assess the association between plasma MGP and plaque characteristics. Furthermore, CVD endpoints (n = 20) were collected over a mean follow-up of 2.6 years. RESULTS: Weighted κ statistics of plasma dp-ucMGP and t-ucMGP and plaque ucMGP were 0.10 (95% CI -0.31 to 0.52) and 0.14 (95% CI -0.20 to 0.48). Higher dp-ucMGP levels tended to be associated with less plaque hemorrhage (ORper 500 nM 0.96; 95% CI 0.92-1.00). No association was found for lipid and calcification content. Cox proportional hazards models showed no association between dp-ucMGP (HRper 200 pM 0.92; 95% CI 0.75-1.11) and an inverse association between t-ucMGP (HRper 500 nM 0.79; 95% CI 0.62-0.99) and cardiovascular events. CONCLUSIONS: Plasma dp-ucMGP and t-ucMGP concentrations do not reflect plaque ucMGP levels. Elevated dp-ucMGP levels may be associated with less plaque hemorrhage, suggestive of more stable plaques. T-ucMGP was not related with markers of plaque stability; however, elevated plasma t-ucMGP levels were associated with a reduced CVD risk.

The abnormal status of uncarboxylated matrix Gla protein species represents an additional mortality risk in heart failure patients with vascular disease.

BACKGROUND: 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. METHODS: 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. RESULTS: 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)]. CONCLUSIONS: 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.

Yogurt drink fortified with menaquinone-7 improves vitamin K status in a healthy population.

Population-based studies have shown an inverse association between dietary menaquinones (MK-n, vitamin K2) intake, coronary calcification and CHD risk, suggesting a potential role of vitamin K in vascular health. To date, the effects of increased menaquinone intake on (markers of) vascular health have been investigated using predominantly food supplements. Dairy products contain many essential nutrients and can serve as a good matrix for food fortification in order to support health. We were therefore interested to study the effects of a menaquinone-fortified yogurt drink (menaquinone as menaquinone-7 (MK-7); 28 µg MK-7/yogurt drink) on vitamin K status and markers of vascular health. The yogurt drink was also fortified with n-3 PUFA, vitamin D, vitamin C, Ca and Mg to support vascular and/or general health. Healthy men (n 32) and postmenopausal women (n 28) with a mean age of 56 (sd 5) years received either basic or fortified yogurt drink twice per d for 12 weeks. MK-7 was efficiently absorbed from the fortified yogurt drink. Levels of circulating MK-7 were significantly increased from 0·28 to 1·94 ng/ml. In accordance, intake of the fortified yogurt drink improved vitamin K status, as measured by significant decreases in uncarboxylated osteocalcin and desphospho-uncarboxylated matrix Gla-protein. No effects were, however, seen on markers of inflammation, endothelial dysfunction and lipid metabolism. In summary, consumption of a yogurt drink fortified with low doses of among others MK-7 for 3 months significantly improved vitamin K status in a healthy population.