Matrix Gla Protein Research Articles

Dephosphorylated uncarboxylated Matrix-Gla-Protein as candidate biomarker for immune-mediated vascular remodeling and prognosis in pulmonary hypertension

Pulmonary arterial hypertension (PAH) is a disease characterized by pulmonary vascular remodeling. Since dephosphorylated-uncarboxylated Matrix Gla-Protein (dp-ucMGP) is associated with cardiovascular mortality in systemic sclerosis, a disease associated with PAH, and immune-system involvement in PAH is increasingly recognized, we investigated the relationship between dp-ucMGP, vascular remodeling and soluble immune-checkpoint proteins in PAH. This prospective cohort study included patients with idiopathic (I)PAH, connective tissue disease (CTD)-PAH, chronic thrombo-embolic PH (CTEPH) and CTD patients without PAH. Patients with IPAH and CTD-PAH were stratified by clinical signs of immune-mediated inflammatory disease (IMID). We measured dp-ucMGP plasma levels, soluble immune-checkpoint proteins (sICPs), and vascular smooth muscle cell (iVSMC) calcification. We found elevated dp-ucMGP levels in all PAH subtypes and CTD patients compared to healthy controls. PAH patients showed increased iVSMC calcification, but no direct correlation was found with dp-ucMGP. IMID-PAH patients had higher dp-ucMGP levels than non-IMID PAH patients. dp-ucMGP correlated with several sICPs in both IPAH and CTD patients; multiple sICPs were elevated in IMID PAH patients. High dp-ucMGP levels in IPAH patients were associated with worse survival. Our findings suggest dp-ucMGP as a potential biomarker of immune-mediated vascular remodeling in PAH. Hence, dp-ucMGP, could help identify PAH patients who might benefit from immunosuppressive therapies.

Correlation between circulating dephosphorylated uncarboxylated matrix Gla protein and vascular calcification in peritoneal dialysis patients.

To explore the association between serum Dephosphorylated uncarboxylated matrix Gla protein (dp-ucMGP) and abdominal aortic calcification (AAC) in peritoneal dialysis (PD) patients. A total 128 PD patients and 120 healthy controls were enrolled into the study. Serum dp-ucMGP was measured by enzyme-linked immunosorbent assay. Abdominal lateral plain radiography was used to evaluate the abdominal aortic calcification score (AACS). PD patients were divided into two groups according to the presence or absence of AAC. The relationships between dp-ucMGP levels and AACS were assessed by Spearman analysis and the value of dp-ucMGP in predicting AAC was evaluated by receiver operating characteristic (ROC). Serum dp-ucMGP in PD patients were significantly higher than controls (p < 0.05). And PD patients with AAC had higher serum dp-ucMGP than that of PD patients without AAC (p < 0.05). The serum dp-ucMGP levels was positively associated with AACS (r = 0.794, p < 0.0001) in PD patients. The multivariate logistic regression analyses showed that serum dp-ucMGP was independent factors of AAC in PD patients (OR = 2.555, 95% CI = 1.415-4.609). The area under ROC curve of dp-ucMGP was 0.9227, the corresponding sensitivity was 0.86, and the specificity was 0.92. Serum dp-ucMGP levels were positively associated with the AACS in PD patients. Higher serum dp-ucMGP level is independently associated with AAC in PD patients.

Role of vitamin K2 and vitamin K cycle enzymes in aortic valvular interstitial cell calcification

Abstract Introduction Calcific aortic valve disease (CAVD) is the most common valve disease. Currently, there is no medical treatment available for CAVD. Vitamin K antagonists promote CAVD while population-based studies suggest that dietary intake of vitamin K reduces the incidence of CAVD in adults. However, randomized trials have so far not proven a clear benefit of vitamin K supplementation on the progression of AVS. Consequently, there is a need for a deeper understanding of the role of vitamin K in valvular calcification. This study aims to further investigate mechanisms of action of vitamin K during valvular calcification. Methods and Results Aortic valve samples were obtained from patients undergoing surgical aortic valve replacement for CAVD and valvular interstitial cells (VIC) were isolated by collagenase II digestion (Fig. 1). VIC expressed typical markers like Vimentin and α-SMA and were cultured in a control medium (CM) or further calcified in a pro-calcifying medium (PCM) containing sodium dihydrogen phosphate and ascorbic acid. PCM led to upregulation of Runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP) expression, and ALP-activity after 7 and 21 days of culture. Moreover, alizarin red staining visualized significant calcium mineral deposition after 21 days of culture (Fig. 2). The addition of the most potent vitamin K2 derivative (Menaquinone-7, MK-7) improved cell viability under both control and calcifying conditions (Fig. 3). Moreover, MK-7 protected VIC from ferroptotic cell death (Fig. 4) and increased expression of the vitamin K-dependent Matrix-Gla-protein (MGP), a major inhibitor of ectopic calcification (Fig. 5). To fulfill its function as an activator of vitamin K-dependent proteins like MGP, vitamin K needs to be reduced to vitamin K hydroquinone by the vitamin K epoxide reductase enzymes VKORC1 and VKORC1L1. In VIC, using our calcification protocol, treatment with PCM led to the downregulation of VKORC1, but not of VKORC1L1, an enzyme with known anti-oxidative properties (Fig. 6). We next performed siRNA-mediated knockdown of VKORC1 and VKORC1L1 in VIC and observed calcification after 7 and 21 days of culture by measuring expression of ALP, RUNX2, quantifying ALP activity, and staining for calcium minerals (alizarin red). Intriguingly, VKORC1L1-knockdown sharply increased the expression of ALP. To further elucidate these findings, we will perform overexpression experiments to analyze, if VKORC1L1 can alleviate PCM-induced calcification Conclusion: Vitamin K2 inhibits in vitro calcification of valvular interstitial cells and upregulates the calcification inhibitor Matrix-Gla-Protein. Our results suggest the involvement of the vitamin K cycle enzyme VKORC1L1, which is known to exhibit anti-oxidative and cytoprotective effects. Further studies are warranted to shed light on the regulation of the enzymes to improve our understanding.

Decoding the mechanical characteristics of the human anterior cruciate ligament entheses through graduated mineralization interfaces

The anterior cruciate ligament is anchored to the femur and tibia via specialized interfaces known as entheses. These play a critical role in ligament homeostasis and joint stability by transferring forces, varying in magnitude and direction between structurally and functionally dissimilar tissues. However, the precise structural and mechanical characteristics underlying the femoral and tibial entheses and their intricate interplay remain elusive. In this study, two thin-graduated mineralization regions in the femoral enthesis (~21 μm) and tibial enthesis (~14 μm) are identified, both exhibiting distinct biomolecular compositions and mineral assembly patterns. Notably, the femoral enthesis interface exhibits progressively maturing hydroxyapatites, whereas the mineral at the tibial enthesis interface region transitions from amorphous calcium phosphate to hydroxyapatites with increasing crystallinity. Proteomics results reveal that Matrix Gla protein uniquely enriched at the tibial enthesis interface, may stabilize amorphous calcium phosphate, while C-type lectin domain containing 11 A, enriched at the femoral enthesis interface, could facilitate the interface mineralization. Moreover, the finite element analysis indicates that the femoral enthesis model exhibited higher resistance to shearing, whereas the tibial enthesis model contributes to tensile resistance, suggesting that the discrepancy in biomolecular expression and the corresponding mineral assembly heterogeneities collectively contribute to the superior mechanical properties of both the femoral enthesis and tibial enthesis models. These findings provide novel perspectives on the structure-function relationships of anterior cruciate ligament entheses, paving the way for improved management of anterior cruciate ligament injury and regeneration.

The associations between functional vitamin K status and all-cause mortality, cardiovascular disease and end-stage kidney disease in persons with type 1 diabetes.

Vitamin K deficiency is common in persons with kidney disease, which is a known complication of diabetes. We aimed to assess the association of vitamin K status as reflected by plasma dephosphorylated-uncarboxylated matrix Gla protein (dp-ucMGP) with mortality, cardiovascular disease (CVD) and progression to end-stage kidney disease (ESKD) in persons with type 1 diabetes. We analysed plasma dp-ucMGP in stored baseline samples from a cohort of 667 persons with type 1 diabetes (baseline visit: 2009-2011). Information on mortality and CVD was obtained through linkage to registers. Cox-proportional hazards models were applied to estimate hazard ratios (HRs) of mortality, CVD and ESKD per one doubling of dp-ucMGP. A total of 53 deaths were recorded during follow-up. Persons with higher dp-ucMGP (reflecting lower vitamin K status) had higher mortality in the unadjusted model (HR: 2.06 [95% confidence interval-CI: 1.22-3.45]), but not in the fully adjusted model (HR: 0.88 [95% CI: 0.44-1.73]). Particularly, adjustment for glomerular filtration rate and urinary albumin excretion rate attenuated the HR. A similar pattern was observed in unadjusted models for incidence of CVD (HR: 1.58 [95% CI: 1.03-2.42]) and risk of ESKD (HR: 7.62 [95% CI: 4.25-13.68]). In the fully adjusted models, the HRs became statistically insignificant. In persons with type 1 diabetes, lower vitamin K status was associated with higher mortality, CVD and progression to ESKD, however, not after adjustment for other risk factors. Interventional studies are needed to elucidate the role of vitamin K in persons with type 1 diabetes.

6683 The Interrelationship of Baseline Vitamin K and Vitamin D Status on Incident Fractures: Results from the VITamin D and OmegA-3 TriaL (VITAL)

Abstract Disclosure: S.H. Chou: None. S.L. Booth: None. D. Ratnarajah: None. N. Cook: None. G. Kotler: None. X. Fu: None. J. Buring: None. J.E. Manson: None. M.S. LeBoff: None. Vitamin D and vitamin K have interdependent roles in bone metabolism. We recently reported that, in the VITamin D and OmegA-3 TriaL (VITAL), daily supplemental vitamin D (2000 IU/d) vs. placebo did not reduce fracture risk in 25,871 U.S. men (aged ≥50) and women (aged ≥55).[1] While vitamin D stimulates transcription and translation of osteocalcin (OC) and matrix Gla protein (MGP), vitamin K is needed to carboxylate and activate these proteins. Older adults tend to have low vitamin K intakes, and low vitamin K status may attenuate effects of vitamin D on bone. In this VITAL ancillary study, we tested in a case-cohort sample of 1,162 participants with fractures and an age-sex-matched subcohort size of 2,652, whether baseline low vitamin K status, alone or in combination with lower 25(OH) vitamin D level, predicts incident total, non-vertebral, and hip fractures. The mean (±SD) age of participants was 68.3±7.2 years, 61.5% were female, and 81.7% was Non-Hispanic White. Fractures were reported on annual questionnaires and adjudicated through medical record review. To assess vitamin K function, percent undercarboxylated OC (%ucOC) and dephosphorylated undercarboxylated MGP ([dp]ucMGP) were measured in fasting baseline blood samples, with %ucOC calculated from measures of ucOC and total OC. Higher levels of %ucOC and (dp)ucMGP indicate lower vitamin K status. Serum 25(OH)D was measured by LC-MS/MS and vitamin K biomarkers by sandwich ELISAs (IDS-iSYS Multi-Discipline Automated System). Participants with incident fracture had higher baseline vitamin K status, as assessed by (dp)ucMGP levels, but this was not corroborated by %ucOC. Compared to participants with low baseline vitamin K status and baseline 25(OH) vitamin D levels below the median (30.0 ng/mL), participants with higher baseline vitamin K and D status had a similar incidence of total and non-vertebral fractures. For the 91 hip fracture cases, baseline status of vitamin K and D did not predict hip fracture incidence. In this ancillary study, low vitamin K status by (dp)ucMGP and %ucOC, alone or in combination with baseline 25(OH) vitamin D levels below the median, was not associated with increased fracture incidence. Ongoing analyses are assessing whether phylloquinone levels as another vitamin K biomarker predict incident fracture risk. Furthermore, we have also previously shown that the effects of supplemental vitamin D on total and hip fractures were not modified by baseline vitamin K status in VITAL, the largest randomized controlled trial of supplemental vitamin D vs. placebo on fractures. From our findings in VITAL, higher vitamin K status does not protect against fractures. 1. LeBoff MS, et al. NEJM. 2022. Presentation: 6/1/2024

9275 The Interrelationship of Baseline Vitamin K and Vitamin D Status on Incident Fractures: Results from the VITamin D and OmegA-3 TriaL (VITAL)

Abstract Disclosure: S.H. Chou: None. S.L. Booth: None. D. Ratnarajah: None. N. Cook: None. G. Kotler: None. X. Fu: None. J. Buring: None. J.E. Manson: None. M.S. LeBoff: None. Vitamin D and vitamin K have interdependent roles in bone metabolism. We recently reported that, in the VITamin D and OmegA-3 TriaL (VITAL), daily supplemental vitamin D (2000 IU/d) vs. placebo did not reduce fracture risk in 25,871 U.S. men (aged ≥50) and women (aged ≥55).[1] While vitamin D stimulates transcription and translation of osteocalcin (OC) and matrix Gla protein (MGP), vitamin K is needed to carboxylate and activate these proteins. Older adults tend to have low vitamin K intakes, and low vitamin K status may attenuate effects of vitamin D on bone. In this VITAL ancillary study, we tested in a case-cohort sample of 1,162 participants with fractures and an age-sex-matched subcohort size of 2,652, whether baseline low vitamin K status, alone or in combination with lower 25(OH) vitamin D level, predicts incident total, non-vertebral, and hip fractures. The mean (±SD) age of participants was 68.3±7.2 years, 61.5% were female, and 81.7% was Non-Hispanic White. Fractures were reported on annual questionnaires and adjudicated through medical record review. To assess vitamin K function, percent undercarboxylated OC (%ucOC) and dephosphorylated undercarboxylated MGP ([dp]ucMGP) were measured in fasting baseline blood samples, with %ucOC calculated from measures of ucOC and total OC. Higher levels of %ucOC and (dp)ucMGP indicate lower vitamin K status. Serum 25(OH)D was measured by LC-MS/MS and vitamin K biomarkers by sandwich ELISAs (IDS-iSYS Multi-Discipline Automated System). Participants with incident fracture had higher baseline vitamin K status, as assessed by (dp)ucMGP levels, but this was not corroborated by %ucOC. Compared to participants with low baseline vitamin K status and baseline 25(OH) vitamin D levels below the median (30.0 ng/mL), participants with higher baseline vitamin K and D status had a similar incidence of total and non-vertebral fractures. For the 91 hip fracture cases, baseline status of vitamin K and D did not predict hip fracture incidence. In this ancillary study, low vitamin K status by (dp)ucMGP and %ucOC, alone or in combination with baseline 25(OH) vitamin D levels below the median, was not associated with increased fracture incidence. Ongoing analyses are assessing whether phylloquinone levels as another vitamin K biomarker predict incident fracture risk. Furthermore, we have also previously shown that the effects of supplemental vitamin D on total and hip fractures were not modified by baseline vitamin K status in VITAL, the largest randomized controlled trial of supplemental vitamin D vs. placebo on fractures. From our findings in VITAL, higher vitamin K status does not protect against fractures. 1. LeBoff MS, et al. NEJM. 2022. Presentation: 6/1/2024

Rationale and Protocol of the ETERNITY-ITA Study: Use of Etelcalcetide for Preserving Vitamin K-Dependent Protein Activity—An Italian Study

Background/Objectives: Chronic kidney disease and mineral bone disorders (CKD-MBD) are frequently associated with an increased risk of both vascular calcifications (VCs) and bone fractures (BFs). The complex pathogenesis of VCs and BFs involves various factors such as calcium overload, phosphate imbalance, and secondary hyperparathyroidism. Key players, such as the vitamin K-dependent proteins (VKDPs) matrix Gla protein (MGP) and bone Gla protein (BGP), have pivotal roles both for VCs and BFs. The VIKI study highlighted that hemodialysis patients treated with calcimimetics had higher levels of total BGP and MGP compared to those untreated, suggesting a potential protective effect of these drugs on BFs and VCs beyond the beneficial effect of reducing PTH levels. Methods: ETERNITY-ITA is a multi-center, comparative effectiveness, observational, longitudinal study that will enroll 160 hemodialysis patients (80 patients treated with Etelcalcetide and 80 age- and sex-matched patients treated with calcitriol or vitamin D analogs). Nephrologists will tailor the target dose of Etelcalcetide on an individual level to achieve the KDIGO PTH target. In the Etelcalcetide-treated group, the addition of calcitriol will be allowed when required by clinical practice (for correction of hypocalcemia). Conclusions: This study will evaluate the real-world effect of Etelcalcetide on VKDP levels, such as BGP and MGP, at 3, 9, and 18 months from baseline. The resulting preservation of vascular and bone health will be assessed for the first time by examining aortic and iliac artery calcifications and vertebral fractures, respectively.

An inducible model for medial calcification based on matrix Gla protein deficiency

Calcific deposits in the arterial media have been associated with a number of metabolic and genetic disorders including diabetes, chronic kidney disease and generalized arterial calcification of infancy. The loss of Matrix Gla protein (MGP) leads to medial elastic lamina calcification (elastocalcinosis) in both humans and animal models. While MGP-deficient (Mgp-/-) mice have been used as a reliable model to study medial elastocalcinosis, these mice are difficult to maintain because of their fragility. Also, these mice are unsuitable for long-term calcification studies in relation to age and sex as most often they die prematurely. In order to circumvent these problems we generated Mgp-/-;ApoE-FGF23 mice, which in addition to the ablation of Mgp alleles, carries a transgene expressing the phosphaturic hormone FGF23. Increased FGF23 levels in the circulation and ensuing hypophosphatemia in these mice lead to a complete prevention of medial calcification until late adulthood. Interestingly, upon feeding a high phosphorus diet for 10 days, we were able to induce medial calcification in 3-week-old Mgp-/-;ApoE-FGF23 mice. Our mineral analyses showed that the calcific deposits in these mice were Our mineral analyses showed that the Ca/P % in the calcific deposits in these mice were comparable to that of 5-week-old Mgp-/- mice although the level of crystallinity differed. The aorta explants from Mgp-/-;ApoE-FGF23 mice resulted in elastocalcinosis in the presence of 2mM phosphate in the culture medium which was completely prevented by pyrophosphate analogue alendronate. Mgp-/-;ApoE-FGF23 mice will be suitable for future in vivo or ex vivo studies examining the effects of age, sex and mineralization inhibitors on medial elastocalcinosis.

Expression of Mgp in Calcification Leiomyoma uterus in postmenopausal women

The Matrix Gla protein (MGP) is an extracellular polypeptide that can inhibit calcification in tissues that express Mgp molecules. An analysis employing histology and immunohistochemistry unveiled the general architecture and detected calcification within the fibroid. The study included gathering twelve samples after confirming through histological examination that the samples were affected by fibroid cysts. Each of these specimens was conserved in a 10% formalin solution. A histological examination was performed using two dyes, hematoxylin and eosin, to demonstrate the general histological organization. The Van Kossa stain was employed to detect the buildup of calcium anions in the tissue. Moreover, the immunohistochemical technique was used to detect the elevated expression of Mgp in the myofibers of leiomyoma-affected myometrium tissue.

Two Members of Vitamin-K-Dependent Proteins, Gla-Rich Protein (GRP) and Matrix Gla Protein (MGP), as Possible New Players in the Molecular Mechanism of Osteoarthritis.

Objectives: The pathophysiology of osteoarthritis is mainly unknown. Matrix Gla protein (MGP) and Gla-rich protein (GRP) are both vitamin-K-dependent mineralization inhibitors. In this study, we aimed to compare the levels of MGP and GRP in the synovial fluid of osteoarthritic (OA) and non-osteoarthritic (non-OA) knee joints. Materials and Methods: Two groups were formed, with one consisting of patients with OA and the other non-OA, serving as a control group. The non-OA group included individuals who had arthroscopic surgery for non-cartilage-related issues. In the OA group, all participants had undergone total knee arthroplasty because of grade 4 primary degenerative osteoarthritis. During the operation, at least 1 mL of knee synovial fluid was collected. The GRP and MGP levels in the synovial fluid were measured using an ELISA kit. Results: The mean age in the OA group (62.03 ± 11.53 years) was significantly higher than that in the non-OA group (47.70 ± 14.49 years; p = 0.0001). GRP levels were significantly higher in the OA group (419.61 ± 70.14 ng/mL) compared to the non-OA group (382.18 ± 62.34 ng/mL; p = 0.037). MGP levels were significantly higher in the OA group (67.76 ± 11.36 ng/mL) compared to the non-OA group (53.49 ± 18.28 ng/mL; p = 0.001). Calcium levels (Ca++) were also significantly higher in the OA group (12.89 ± 3.43 mg/dL) compared to the non-OA group (9.51 ± 2.15 mg/dL; p = 0.0001). There was a significantly positive correlation between MGP levels and age (p = 0.011, R = +0.335). Linear regression analysis was performed to determine the effect of age on MGP levels (p = 0.011, R-Square = 0.112). The dependent variable in this analysis was MGP (ng/mL), and age was the predictor. Conclusions: In conclusion, both GRP and MGP are potentially usable biomarkers in osteoarthritis. However, GRP seems to be more valuable because it is not associated with age. In the future, both proteins could provide important contributions to the diagnosis and treatment of osteoarthritis.

Deciphering Breast Origin in Malignant Effusions: The Diagnostic Utility of an MGP, GATA-3, and TRPS-1 Immunocytochemical Panel

Introduction: Defining the origin of metastatic cancer is crucial for establishing an optimal treatment strategy, especially when obtaining sufficient tissue from secondary malignancies is limited. While cytological examination is often used in this diagnostic setting, morphologic analysis alone often fails to differentiate metastases derived from the breast from other primaries. The hormone receptor, human epidermal growth factor receptor-2, gross cystic disease fluid protein 15, and mammaglobin immunohistochemistry are often used to diagnose metastatic breast cancer. However, their effectiveness decreases in estrogen receptor (ER)-negative breast cancers, including the triple-negative breast cancer (TNBC) subtype. Methods: We conducted a comprehensive evaluation of GATA-binding protein 3 (GATA-3), trichorhinophalangeal syndrome type 1 (TRPS-1), and Matrix Gla Protein (MGP) immunochemistry across 140 effusion cytology specimens with metastatic adenocarcinoma derived from various primaries, including the breast, colon, pancreaticobiliary, lung, tubo-ovarian, and stomach. Results: The expression rates of these immunomarkers were significantly higher in metastatic cancers originating from the breast than other primaries. In TNBC, TRPS-1 (80.00%) and MGP (65.00%) exhibited higher positivity rates compared to GATA-3 (40.00%). Additionally, our data suggest that an immunohistochemical panel comprising MGP, GATA-3, and TRPS-1 significantly enhances the detection of metastatic breast cancer in effusion cytology specimens, including TNBC in particular. When considering dual-marker positivity, the diagnostic accuracy was found to be 89.29% across all breast cancer subtypes and 92.93% for TNBC. Conclusions: MGP appears to be a robust marker for identifying metastatic breast cancer in malignant effusions, especially TNBC. MGP notably enhances diagnostic accuracy when incorporated together with GATA-3 and TRPS-1 in an immunohistochemical panel.

Rapamycin increases murine lifespan but does not reduce mineral volume in the Matrix GLA Protein (MGP) knockout mouse model of medial arterial calcification.

Peripheral artery disease (PAD) is the narrowing of the arteries that carry blood to the lower extremities. PAD has been traditionally associated with atherosclerosis. However, recent studies have found that medial arterial calcification (MAC) is the primary cause of chronic limb ischemia below the knee. MAC involves calcification of the elastin fibers surrounding smooth muscle cells (SMCs) in arteries. Matrix GLA Protein (MGP) binds circulating calcium and inhibits vascular calcification. Mgp -/- mice develop severe MAC and die within 8 weeks of birth due to aortic rupture or heart failure. We previously discovered a rare genetic disease Arterial Calcification due to Deficiency in CD73 (ACDC) in which patients present with extensive MAC in their lower extremity arteries. Using a patient-specific induced pluripotent stem cell model we found that rapamycin inhibited calcification. Here we investigated whether rapamycin could reduce MAC in vivo using Mgp -/- mice as a model. Mgp +/+ and Mgp -/- mice received 5mg/kg rapamycin or vehicle. Calcification content was assessed via microCT, and vascular morphology and extracellular matrix content assessed histologically. Immunostaining and western blot analysis were used to examine SMC phenotypes and cellular functions. Rapamycin prolonged Mgp -/- mice lifespan, decreased mineral density in the arteries, and increased smooth muscle actin protein levels, however, calcification volume, vessel morphology, SMC proliferation, and autophagy flux were all unchanged. These findings suggest that rapamycin's effects in the Mgp -/- mouse are independent of the vascular phenotype.

Epigenetics enters the stage in vascular malformations.

Cerebral arteriovenous malformations represent the most common form of vascular malformations and can cause recurrent bleeding and hemorrhagic stroke. The current issue of the JCI features an article by Zhao et al. describing a mouse model of cerebral arteriovenous malformations. Endothelial cells lacking matrix Gla protein, a BMP inhibitor, underwent epigenetic changes characteristic of an endothelial-to-mesenchymal fate transition. The authors uncovered a two-step process for this transition controlled by the epigenetic regulator histone deacetylase 2 (HDAC2), which controls endothelial cell differentiation, and by enhancer of zeste homolog 1 (EZH1), which suppressed mesenchymal fate. This discovery provides a promising entry point for preventive pharmacological interventions.

Rivaroxaban versus vitamin K antagonist treatment on the progression of coronary calcification: the IRIVASC-trial

Vitamin K antagonists (VKA) remain the only option of anticoagulation for people with mechanical valve replacement and due to their wider availability and lower acquisition costs, VKA’s remain widely used in low- and middle-income countries. It has been suggested that prolonged use of VKAs can increase the development of vascular and valvular calcification, though this effect has not been examined in larger randomized prospective trials. This investigator-initiated multicenter, prospective, randomized, open-label interventional trial randomized patients with baseline coronary or valvular calcification and an indication for prolonged oral anticoagulation therapy to Marcumar or Rivaroxaban. Patients were followed-up through repeat coronary computed tomographies to measure the progression of coronary and valvular calcification for up to 24 months. 192 patients were randomized between 2013 and 2018 to receive either Rivaroxaban or Marcumar and followed for up to 24 months. Coronary calcification significantly increased over time although there was no significant difference in progression between the groups after 12 and 24 months as measured by the Agatston score [360.7 (90.2; 1075.3) vs 380.4 (136.4; 1546.9) p = 0.69], the volume score [295.8 (93.0; 995.3) vs 335.5 (128.7; 1316.9) p = 0.95] and the mass score [58.5 (15.9; 172.0) vs 71.1 (24.8; 257.3) p = 0.5]. Dephosphorylated, uncarboxylated matrix Gla Protein (Dp-ucMGP) significantly decreased in the VKA group [Δ dp-uc MGP – 95.2 (− 554.1; 156.0) vs 231.3 (− 59.7; 388.1) p < 0.001]. There does not appear to be a relevant effect of vitamin K inhibition by the vitamin K antagonist marcumar upon coronary calcification.

The Importance of Vitamin K and the Combination of Vitamins K and D for Calcium Metabolism and Bone Health: A Review.

The aim of the present review is to discuss the roles of vitamin K (phylloquinone or menaquinones) and vitamin K-dependent proteins, and the combined action of the vitamins K and D, for the maintenance of bone health. The most relevant vitamin K-dependent proteins in this respect are osteocalcin and matrix Gla-protein (MGP). When carboxylated, these proteins appear to have the ability to chelate and import calcium from the blood to the bone, thereby reducing the risk of osteoporosis. Carboxylated osteocalcin appears to contribute directly to bone quality and strength. An adequate vitamin K status is required for the carboxylation of MGP and osteocalcin. In addition, vitamin K acts on bone metabolism by other mechanisms, such as menaquinone 4 acting as a ligand for the nuclear steroid and xenobiotic receptor (SXR). In this narrative review, we examine the evidence for increased bone mineralization through the dietary adequacy of vitamin K. Summarizing the evidence for a synergistic effect of vitamin K and vitamin D3, we find that an adequate supply of vitamin K, on top of an optimal vitamin D status, seems to add to the benefit of maintaining bone health. More research related to synergism and the possible mechanisms of vitamins D3 and K interaction in bone health is needed.

Comparative Study Evaluating the Effect of the Administration of Vitamin K1 versus Placebo on Vascular Calcification in Haemodialysis Patients

Abstract Background Cardiovascular calcification is a risk factor and contributor to morbidity and mortality in End stage kidney disease patients. Cardiovascular calcification is most likely due to an imbalance of promoters (e.g. Calcium and phosphate) and inhibitors (e.g. fetuin-A and matrix Gla protein). Aim of the Work We aimed to study the effect of oral vitamin k1 on serum carboxylated Matrix gla protein in patients on maintenance hemodialysis and to study its effect as an important marker of vascular calcification. Patients and Methods This Placebo Controlled clinical trial was conducted for 3 months on 80 adult ESRD patients on regular Hemodialysis randomly allocated into 2 groups of either vitamin K1 versus oral placebo tablet administration for 3 months. Patients in both groups were age and sex matched, study group included 18 (45%) males and 22 (55%) females with mean age ± SD 47.350 ± 14.420 years, while the placebo group included 16 (40%) males and 24 (60%) with mean age ± SD 49.500 ± 14.509 years, with no significant difference between both groups as regard demographic data, access of hemodialysis, and duration of Hemodialysis. Results There was no significant change in bone parameters (serum Ca, PO4 &amp; Ca/PO4 product) after 3 months of vit K1 administration compared to baseline in the study group. Serum phosphorus levels showed a minimal, yet statistically significant decrease after 3 months of placebo administration, this might be attributed to the different doses of PO4 binders in patients of both groups. Consequently, Ca/ PO4 product showed a statistically significant decrease after 3 months of placebo administration (P = 0.002), mostly attributed to the significant decrease in serum phosphorus in the same group over the same period. We observed that serum MGP levels significantly increased after administration of vitamin k1 in study group (P &amp;lt; 0.001) with 78.05% increase. However, a much lower increase, yet statistically significant increase in serum MGP level was noticed in the placebo group (P &amp;lt; 0.001) with 40.60 % increase. There was no statistically significant difference between the two groups according to their risk factors regarding smoking, HTN, HCV, DM, and ISHD. Conclusion We concluded that Oral vitamin K1 therapy significantly increased serum active form of Matrix GLA protein levels among hemodialysis patients with potential decrease in cardiovascular calcification and cardiovascular diseases.

Thrombospondin 2, matrix Gla protein and digital analysis identified distinct fibroblast populations in fibrostenosing Crohn’s disease

Fibrosis is an important complication in inflammatory bowel diseases. Previous studies suggest an important role of matrix Gla protein (MGP) and thrombospondin 2 (THBS2) in fibrosis in various organs. Our aim was to analyse their expression together with regulatory miRNAs in submucosal and subserosal fibroblasts in ulcerative colitis (UC) and Crohn’s disease (CD) using immunohistochemistry and qPCR. Digital pathology was used to compare collagen fibre characteristics of submucosal and subserosal fibrosis. Immunohistochemistry showed expression of MGP, but not THBS2 in submucosa in UC and CD. In the subserosa, there was strong staining for both proteins in CD but not in UC. qPCR showed significant upregulation of THBS2 and MGP genes in CD subserosa compared to the submucosa. Digital pathology analysis revealed higher proportion of larger and thicker fibres that were more tortuous and reticulated in subserosal fibrosis compared to submucosal fibrosis. These results suggest distinct fibroblast populations in fibrostenosing CD, and are further supported by image analysis showing significant differences in the morphology and architecture of collagen fibres in submucosal fibrosis in comparison to subserosal fibrosis. Our study is the first to describe differences in submucosal and subserosal fibroblast populations, contributing to understanding of the pathogenesis of fibrostenosis in CD.

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.

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.