Dual-sgRNA CRISPRa System for Enhanced MK-7 Production and Salmonella Infection Mitigation in Bacillus subtilis natto Applied to Caco-2 Cells

This study optimized the menaquinone-7 (MK-7) synthetic pathways in Bacillus subtilis (B. subtilis) natto NB205, a strain that originated from natto, to enhance its MK-7 production. Utilizing mutation breeding, we developed NBMK308, a mutant strain that demonstrated a significant 117.23% increase in MK-7 production. A comprehensive transcriptome analysis identified two key genes, ispA and ispE, as being critical in MK-7 synthesis. The dual-sgRNA CRISPRa system was utilized to achieve precise regulation of ispA and ispE in the newly engineered strain, A3E3. This strategic modulation resulted in a significant enhancement of MK-7 production, achieving increases of 20.02% and 201.41% compared to traditional overexpression systems and the original strain NB205, respectively. Furthermore, the fermentation supernatant from A3E3 notably inhibited Salmonella invasion in Caco-2 cells, showcasing its potential for combating such infections. The safety of the dual-sgRNA CRISPRa system was confirmed through cell assays. The utilization of the dual-sgRNA CRISPRa system in this study was crucial for the precise regulation of key genes in MK-7 synthesis, leading to a remarkable increase in production and demonstrating additional therapeutic potential in inhibiting pathogenic infections. This approach effectively combined the advantages of microbial fermentation and biotechnology, addressing health and nutritional challenges.

Vitamin K supplementation and bone mineral density in dialysis: results of the double-blind, randomized, placebo-controlled RenaKvit trial

BACKGROUND

Vitamin K deficiency is highly prevalent in patients on dialysis and may contribute to their low bone mineral density (BMD) and increased risk of fracture. This study investigated the effect of menaquinone-7 (MK-7) supplementation on BMD in patients on chronic dialysis.

METHODS

In a multicentre, double-blind, placebo-controlled intervention trial, 123 patients on chronic dialysis were randomised to a daily oral supplement of either MK-7 360 µg or placebo for 2 years. BMD of the distal radius (1/3, mid, ultradistal and total), femoral neck, lumbar spine (L1-L4) and whole body was assessed by dual-energy X-ray absorptiometry. Serum levels of vitamin K1 and MK-7 and plasma levels of total osteocalcin, dephosphorylated-uncarboxylated matrix Gla protein and protein induced by vitamin K absence II were measured to assess vitamin K status.

RESULTS

After 2 years, an accelerated BMD loss of the 1/3 distal radius was found with MK-7 supplementation {mean difference of changes relative to placebo -0.023 g/cm2 [95% confidence interval (CI) -0.039 to -0.008]}, whereas the decrease in lumbar spine BMD seen in the placebo group was prevented [mean difference of changes between groups 0.050 g/cm2 (95% CI 0.015-0.085)]. No significant effects were observed at the remaining skeletal sites. Vitamin K status strongly improved in MK-7-supplemented participants.

CONCLUSION

Compared with placebo, an accelerated BMD loss of the 1/3 distal radius was found after 2 years of MK-7 supplementation, whereas a decline in lumbar spine BMD was prevented. As such, MK-7 supplementation might modify BMD site-specifically in patients on dialysis. In aggregate, our findings do not support MK-7 supplementation to preserve bone in patients on dialysis.

Characterization of K-binding factor involved in water-soluble complex of menaquinone-7 produced by Bacillus subtilis natto

Vitamin Ks are expected to contribute bone and cardiovascular health. Especially, menaquinone-7 has a higher bioavailability and a longer half-life than other vitamin Ks in the human body. However, their low water-solubility limits their application. On the other hand, Bacillus subtilis natto produces a water-soluble complex, which comprises menaquinone-7 and peptides. The peptide named K-binding factor (KBF) has been reported as the main component of the complex. In the present, the structural characteristics of KBF were studied. Mass spectrometry showed significant peaks at m/z = 1050, while the previous PAGE suggested that molecular weight of KBF was ~ 3k. Amino acid analysis revealed that the 1k peptides were the various combinations of nine amino acids, among which Asx, Glx, Val, Leu and Met were found to be the most abundant. The peptides could serve as detergent properties. The 1k peptides could be isolated by reverse-phase high performance liquid chromatography. The bundle of three 1k detergent-like peptides would participate to the micelle structure containing menqauinone-7 inside. In conclusion, a basic unit of KBF would be the ~ 1k peptides, and the three basic unit assemble to the ~ 3k bundle, then the bundle form a water-soluble micelle including menqauinone-7 inside.

Effects of Menaquinone-7 on the Bone Health of Growing Rats under Calcium Restriction: New Insights from Microbiome-Metabolomics

Insufficient calcium intake during growth is a global public health concern. The aim of this study was to investigate the effects of dietary menaquinone-7 (MK-7) on bone accrual in growing Sprague-Dawley rats under calcium restriction. Following 13 weeks of treatment, various bone quality parameters, including microarchitecture, were measured. Fecal and cecal samples were subjected to microbiome (16S rRNA gene sequencing) analyses, while metabolomics analysis of the cecum and humerus samples was analyzed based on UHPLC-Q/TOF-MS. We found that calcium deficiency diminished the richness of the microbiome and disrupted microbiome composition, accompanied by an elevation in the relative abundance of Parasutterella. Furthermore, calcium insufficiency escalated the level of isovaleric acid and modified the metabolic profiles. MK-7 supplementation significantly increased the cortical thickness, cortical bone area, and the calcium content of the femur. Apart from improving bone calcium deposition and diminishing bone resorption, the mechanisms underlying the beneficial effects of MK on bone quality also involve the modulation of the host's metabolic pathways and the composition of gut microbiota. The gut-bone axis holds promise as an efficacious target for ameliorating calcium deficiency in children's bone quality, and MK-7 is a promising dietary supplement from this perspective.

Effect of Menaquinone-7 Supplementation on Arterial Stiffness in Chronic Hemodialysis Patients: A Multicenter Randomized Controlled Trial

BACKGROUND

There is a very high prevalence of subclinical vitamin K deficiency in patients requiring hemodialysis (HD), and this problem is associated with vascular calcification and arterial stiffness. Vitamin K2 (MK-7) supplementation can improve vitamin K status in HD patients. However, the benefits of vitamin K supplementation on arterial stiffness have still not been established. The present study was conducted to evaluate the efficacy of menaquinone-7 (MK-7) supplementation on arterial stiffness in chronic HD patients.

METHODS

This open-label multicenter randomized clinical trial was conducted in 96 HD patients who had arterial stiffness, defined by high carotid femoral pulse wave velocity (cfPWV ≥ 10 m/s). The patients were randomly assigned to receive oral MK-7 (375 mcg once daily) for 24 weeks (n = 50) or standard care (control group; n = 46). The change in cfPWV was the primary outcome.

RESULTS

Baseline parameters were comparable between the two groups. There was no significant difference in the change in cPWV at 24 weeks between the MK-7 group and standard care [-6.0% (-20.2, 2.3) vs. -6.8% (-19.0, 7.3), p = 0.24]. However, we found that MK-7 significantly decreased cPWV in patients with diabetes [-10.0% (-15.9, -0.8) vs. 3.8% (-5.8, 11.6), p = 0.008]. In addition, the MK-7 group had a lower rate of arterial stiffness progression, compared to controls (30.2% vs. 39.5%, p = 0.37), especially in diabetes patients (21.4% vs. 72.7%, p = 0.01). No serious adverse events were observed during the 24 weeks.

CONCLUSION

Vitamin K supplements provided a beneficial impact in lowering the rate of arterial stiffness progression in chronic hemodialysis patients with diabetes. Possible benefits on cardiovascular outcomes require further investigation.

Effects of Alkali Stress on the Growth and Menaquinone-7 Metabolism of Bacillus subtilis natto

Menaquinone-7 (MK-7) is an important vitamin K₂, synthesized from the menaquinone parent ring and seven isoprene side chains. Presently, the synthesis of MK-7 stimulated by environmental stress primarily focuses on oxygen stress, while the effect of alkali stress is rarely studied. Therefore, this study researched the effects of alkali stress on the fermentation performance and gene expression of Bacillus subtilis natto. The organism’s growth characteristics, biomass, sporogenesis, MK-7 biosynthesis, and gene expression were analyzed. After a pH 8.5 stress adaptation treatment for 0.5 h and subsequent fermentation at pH 8.5, which promoted the growth of the strain and inhibited the spore formation rate. In addition, biomass was significantly increased (P < 0.05). The conversion rate of glycerol to MK-7 was 1.68 times higher than that of the control group, and the yield of MK-7 increased to 2.10 times. Transcriptomic analysis showed that the MK-7 high-yielding strain had enhanced carbon source utilization, increased glycerol and pyruvate metabolism, enhanced the Embden-Meyerhof pathway (EMP), tricarboxylic acid (TCA) circulation flux, and terpenoid biosynthesis pathway, and promoted the accumulation of acetyl-CoA, the side-chain precursor of isoprene. At the same time, the up-regulation of transketolase increased the metabolic flux of the pentose phosphate (HMP) pathway, which was conducive to the accumulation of D-erythrose 4-phosphate, the precursor of the menadione parent ring. This study’s results contribute to a better understanding of the effects of environmental stress on MK-7 fermentation by Bacillus subtilis natto and the molecular regulatory mechanism of MK-7 biosynthesis.

Vitamin K Supplementation for Prevention of Vascular Calcification in Chronic Kidney Disease Patients: Are We There Yet?

Chronic Kidney Disease (CKD) patients are at high risk of presenting with arterial calcification or stiffness, which confers increased cardiovascular mortality and morbidity. In recent years, it has become evident that VC is an active process regulated by various molecules that may act as inhibitors of vessel mineralization. Matrix Gla Protein (MGP), one the most powerful naturally occurring inhibitors of arterial calcification, requires vitamin K as a co-factor in order to undergo post-translational γ-carboxylation and phosphrorylation and become biologically active. The inactive form of MGP (dephosphorylated, uncarboxylated dp-ucMGP) reflects vitamin K deficiency and has been repeatedly associated with surrogate markers of VC, stiffness, and cardiovascular outcomes in CKD populations. As CKD is a state of progressive vitamin K depletion and VC, research has focused on clinical trials aiming to investigate the possible beneficial effects of vitamin K in CKD and dialysis patients. In this study, we aim to review the current evidence regarding vitamin K supplementation in uremic patients.

Vitamin K Insufficiency in the Indian Population: Pilot Observational Epidemiology Study

Background

The fat-soluble K vitamins K1 and K2 play an essential role in the blood coagulation cascade and are made available predominantly through selective dietary intakes. They are less known for their nonessential roles in a family of vitamin K–dependent proteins that promote various functions of organs and systems in the body. A lack of vitamin K can characterize vitamin and nutritional element insufficiency, which is different from a clinically apparent vitamin deficiency.

Objective

This epidemiological study evaluated the nutritional status of vitamin K in a sample of the Indian population and vitamin K content in staple Indian foods.

Methods

Serum levels of vitamin K1 and vitamin K2 in the form of menaquinone-7 (MK-7) were assessed via high-performance liquid chromatography coupled with fluorescence detection in 209 patients with type 2 diabetes, 50 healthy volunteers, and common staple foods in India.

Results

After comparing populations with high and low serum vitamin K levels from various geographical regions, our results indicated that the sample of healthy Indian individuals and the sample of Indian patients with type 2 diabetes had low (insufficient) levels of vitamin K2 (MK-7; range 0.3-0.4 ng/mL). No significant differences existed in vitamin K1–related and MK-7–related values between healthy male and female subjects, between male and female subjects with diabetes, and between the healthy sample and the sample of patients with diabetes. The staple, commonly consumed Indian foods that were tested in this study had undetectable levels of vitamin K2, while levels of vitamin K1 varied widely (range 0-37 µg/100 g).

Conclusions

Based on our sample’s low serum levels of vitamin K2 (MK-7) as well as the low levels of vitamin K2 in their typical diet, we propose that the general Indian population could benefit from the consumption of vitamin K2 in the form of MK-7 supplements.

Trial Registration

Clinical Trials Registry - India CTRI/2019/05/014246; http://ctri.nic.in/Clinicaltrials/showallp.php?mid1=21660&EncHid=&userName=014246; Clinical Trials Registry - India CTRI/2019/03/018278; http://ctri.nic.in/Clinicaltrials/showallp.php?mid1=32349&EncHid=&userName=018278

Simultaneous Determination of Vitamins D3 (Calcitriol, Cholecalciferol) and K2 (Menaquinone-4 and Menaquinone-7) in Dietary Supplements by UHPLC

The content and composition of dietary supplements is of great interest due to their increasing consumption and variety of available brand offered in the market. Accurate determination of vitamins is important for the improvement of dietary supplement quality and nutrition assessments. In this regard, the simultaneous determination of vitamin D3 (calcitriol-CT and cholecalciferol-CHL) and K2 (menaquinone-4-MK-4 and menaquinone-7-MK-7) in dietary supplements was developed by using ultra-high-pressure liquid chromatography (UHPLC). The overall runtime per sample was above 35 min, with the retention times of 2.40, 6.59, 7.06, and 32.6 min for vitamin D3 (CT and CHL) and vitamin K2 (MK-4 and MK-7), respectively. The limits of detection and limits of quantification for the target nutritional compounds ranged between 0.04-0.05 µg/mL, respectively. The validation results indicated that the method had reasonable linearity (R² ≥ 0.9990), good recovery (>82%), satisfactory intra-day precision (≤1.9%) and inter-day precision (≤3.5%), and high selectivity and specificity. The validated UHPLC method was demonstrated to be precise, accurate, and robust for the simultaneous determination of vitamins D3 (CT and CHL) and K2 (MK-4 and MK-7) in dietary supplements.

First Clinical Trial of a Newly Developed, Low Menaquinone-7, Fermented Soybean Natto in Warfarin-Dependent Patients

Bacillus subtilis fermented soybeans (natto) contain high vitamin K2 levels, mostly as menaquinone-7 (MK-7), and must be avoided by warfarin-dependent patients. This is the first report which demonstrates the characteristics and clinical relevance of a low MK-7 natto for such patients. We generated a novel, mutant B. subtilis strain TTCC2051 with short-term fermentation and reduced MK-7 production, yielding 19-24% of the normal MK-7 content. After functional assessments and a preclinical trial, 10 warfarin-dependent patients underwent a clinical trial with a 7-day ingestion test of the low MK-7 natto. Functional assessments were satisfactory, and the preclinical trial showed no increases in plasma MK-7 levels after 7 days of ingestion. In the clinical trial, 20 g/day of the low MK-7 natto significantly increased plasma MK-7 levels while 10 g/day did not. However, neither dose of low MK-7 natto changed international normalized ratio of prothrombin time (PT-INR) values in either group. The low MK-7 natto neither changed PT-INR values nor precipitated adverse events if ingested with a once-daily maximum of 20 g (46 μg of MK-7). Thus, this novel food product has potential for consumption by warfarin-dependent patients.

Advances in Enhanced Menaquinone-7 Production From Bacillus subtilis

The production of nutraceutical compounds through biosynthetic approaches has received considerable attention in recent years. For example, Menaquinone-7 (MK-7), a sub-type of Vitamin K2, biosynthesized from Bacillus subtilis (B. subtilis), proved to be more efficiently produced than the conventional chemical synthesis techniques. This is possible due to the development of B. subtilis as a chassis cell during the biosynthesis stages. Hence, it is imperative to provide insights on the B. subtilis membrane permeability modifications, biofilm reactors, and fermentation optimization as advanced techniques relevant to MK-7 production. Although the traditional gene-editing method of homologous recombination improves the biosynthetic pathway, CRISPR-Cas9 could potentially resolve the drawbacks of traditional genome editing techniques. For these reasons, future studies should explore the applications of CRISPRi (CRISPR interference) and CRISPRa (CRISPR activation) system gene-editing tools in the MK-7 anabolism pathway.

Vitamin K2 (Menaquinone-7) supplementation does not affect vitamin K-dependent coagulation factors activity in healthy individuals

BACKGROUND

Vitamin K has long been regarded as a procoagulant drug by physicians, and concerns have been raised with regard to its effects on hemostasis. Although many studies have shown that vitamin K supplementation is safe for thrombotic events, the effect of vitamin K supplementation on the activities of vitamin K dependent procoagulation factors in healthy individuals is not available.

OBJECTIVES

This study aimed to investigate whether vitamin K2 supplementation at recommended doses affects the activity of vitamin K dependent procoagulation factors in healthy individuals without any anticoagulation treatment.

DESIGN

Forty healthy volunteers between 25 and 40 years of age were recruited. Menaquinone-7 (MK-7) was administrated at 90 μg for 30 days. Prothrombin time (PT), activated partial thromboplastin time (APTT), thrombin time (TT), and blood coagulation factors II, VII, IX, and X activities and Protein induced by vitamin K absence or antagonist-II (PIVKA-II) were measured on days 0 and 30 after MK-7 administration.

RESULTS

PT, APTT, and TT showed no significant differences on day 30 when compared with baseline. The activities of coagulation factors II, VII, IX, and X on day 30 showed no significant differences with those at baseline. PIVKA-II levels were unchanged after 30 days of MK-7 supplementation.

CONCLUSIONS

MK-7 supplementation at recommended dosage does not affect vitamin K-dependent coagulation factors' coagulation activity, and does not enhance the carboxylation of prothrombin in healthy individuals. This indicated that MK-7 administration does not alter hemostatic balance in healthy populations without anticoagulation treatment.

Highly Efficient Production of Menaquinone-7 from Glucose by Metabolically Engineered Escherichia coli

Menaquinone-7 (MK-7) possesses wide health and medical value, and the market demand for MK-7 has increased. Metabolic engineering for MK-7 production in Escherichia coli still remains challenging due to the characteristics of the competing quinone synthesis, and cells mainly synthesized menaquinones under anaerobic conditions. To increase the production of MK-7 in engineered E. coli strains under aerobic conditions, we divided the whole MK-7 biosynthetic pathway into three modules (MVA pathway, DHNA pathway, and MK-7 pathway) and systematically optimized each of them. First, by screening and enhancing Idi expression, the amounts of MK-7/DMK-7 increased significantly. Then, in the MK-7 pathway, by combinatorial overexpression of endogenous MenA and exogenous UbiE, and fine-tuning the expression of HepPPS, MenA, and UbiE, 70 μM MK-7 was achieved. Third, the DHNA synthetic pathway was enhanced, and 157 μM MK-7 was achieved. By the combinational metabolic engineering strategies and membrane engineering, an efficient metabolic engineered E. coli strain for MK-7 synthesis was developed, and 200 μM (129 mg/L) MK-7 was obtained in shake flask experiment, representing a 306-fold increase compared to the starting strain. In the scale-up fermentation, 2074 μM (1350 mg/L) MK-7 was achieved after 52 h fermentation with a productivity of 26 mg/L/h. This is the highest titer of MK-7 ever reported. This study offers an alternative method for MK-7 production from biorenewable feedstock (glucose) by engineered E. coli. The high titer of our process should make it a promising cost-effective resource for MK-7.

Vitamin K supplementation and arterial calcification in dialysis: results of the double-blind, randomized, placebo-controlled RenaKvit trial

Background

Arterial calcification is associated with cardiovascular mortality in dialysis patients. Active matrix Gla protein (MGP) is a vitamin K-dependent inhibitor of arterial calcification. Elevated plasma concentrations of inactive MGP, i.e. dephosphorylated-uncarboxylated MGP (dp-ucMGP), are prevalent in dialysis patients. MGP inactivity might contribute to arterial calcification. We investigated whether vitamin K supplementation had an effect on arterial calcification in chronic dialysis patients.

Methods

In a 2-year, double-blind, placebo-controlled intervention trial, 48 dialysis patients were randomized to vitamin K [menaquinone-7 (MK-7), 360 µg daily] or placebo. MK-7 in serum and dp-ucMGP in plasma were used to assess vitamin K status. Carotid-femoral pulse wave velocity (cfPWV) and scores of coronary arterial calcification (CAC) and abdominal aortic calcification (AAC) were used to assess arterial calcification.

Results

Thirty-seven participants completed Year 1, and 21 completed Year 2. At Year 2, serum MK-7 was 40-fold higher, and plasma dp-ucMGP 40% lower after vitamin K supplementation compared with placebo {mean dp-ucMGP difference: −1380 pmol/L [95% confidence interval (CI) −2029 to −730]}. There was no significant effect of vitamin K supplementation on cfPWV [mean difference at Year 2: 1.2 m/s (95% CI −0.1 to 2.4)]. CAC Agatston score increased significantly in vitamin K supplemented participants, but was not significantly different from placebo [mean difference at Year 2: 664 (95% CI −554 to 1881)]. AAC scores increased in both groups, significantly so within the placebo group at Year 1, but with no significant between-group differences.

Conclusions

Vitamin K supplementation improved vitamin K status, but did not hinder or modify the progression of arterial calcification in dialysis patients.

Menaquinone-7 Supplementation Improves Osteogenesis in Pluripotent Stem Cell Derived Mesenchymal Stem Cells

Development of clinical stem cell interventions are hampered by immature cell progeny under current protocols. Human mesenchymal stem cells (hMSCs) are characterized by their ability to self-renew and differentiate into multiple lineages. Generating hMSCs from pluripotent stem cells (iPSCs) is an attractive avenue for cost-efficient and scalable production of cellular material. In this study we generate mature osteoblasts from iPSCs using a stable expandable MSC intermediate, refining established protocols. We investigated the timeframe and phenotype of cells under osteogenic conditions as well as the effect of menaquinone-7 (MK-7) on differentiation. From day 2 we noted a significant increase in RUNX2 expression under osteogenic conditions with MK-7, as well as decreases in ROS species production, increased cellular migration and changes to dynamics of collagen deposition when compared to differentiated cells that were not treated with MK-7. At day 21 OsteoMK-7 increased alkaline phosphatase activity and collagen deposition, as well as downregulated RUNX2 expression, suggesting to a mature cellular phenotype. Throughout we note no changes to expression of osteocalcin suggesting a non-canonical function of MK-7 in osteoblast differentiation. Together our data provide further mechanistic insight between basic and clinical studies on extrahepatic activity of MK-7. Our findings show that MK-7 promotes osteoblast maturation thereby increasing osteogenic differentiation.

Evaluation of synergistic combination comprising magnesium orotate, menaquinone-7, and cholecalciferol for management of type 2 diabetes and dyslipidemia

Epidemiological outburst of type 2 diabetes is of great global concern. T2D starts with Insulin Resistance (IR) which arises largely due to environmental factors and to a lesser extent due to genetic factor. IR gradually develops into T2D and encompasses a wide array of conditions including Impaired Glucose Tolerance (IGT), hyperinsulinemia, Impaired Fasting Glucose (IFG), and Impaired Insulin Release (IIR). Initiation of IR increases the risk of Cardiovascular Diseases (CVD). Therefore, early diagnosis and management of IR and its related outcomes (hyperinsulinemia, hyperglycemia, and dyslipidemia) should be the prime focus of intervention therapies. Present research aimed to evaluate the synergistic combination of Magnesium orotate (MOD), Menaquinone- 7 (MK-7), and Cholecalciferol (CHOL) for the management of these therapeutic targets in the Streptozotocin-Nicotinamide-induced T2D Wistar rat model. Synergistic combination was found to be superior over its individual components in management of hyperglycemia, impaired insulin secretion, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), and dyslipidemia (p < 0.01 or p < 0.05). Its effect was found to be equivalent or better than reference drugs (p < 0.01 or p < 0.05). Histopathological analysis depicted that combination treatment was able to regenerate and preserve pancreatic β-cell mass in diabetic rats. In conclusion, combination studied in present research can be evaluated further under clinical settings for management of IR and its related outcomes.

MK-7 and Its Effects on Bone Quality and Strength

Vitamin K acts as a cofactor and is required for post-translational γ-carboxylation of vitamin K-dependent proteins (VKDP). The current recommended daily intake (RDI) of vitamin K in most countries has been established based on normal coagulation requirements. Vitamin K1 and menaquinone (MK)-4 has been shown to decrease osteocalcin (OC) γ-carboxylation at RDI levels. Among the several vitamin K homologs, only MK-7 (vitamin K2) can promote γ-carboxylation of extrahepatic VKDPs, OC, and the matrix Gla protein at a nutritional dose around RDI. MK-7 has higher efficacy due to its higher bioavailability and longer half-life than other vitamin K homologs. As vitamin K1, MK-4, and MK-7 have distinct bioactivities, their RDIs should be established based on their relative activities. MK-7 increases bone mineral density and promotes bone quality and strength. Collagen production, and thus, bone quality may be affected by MK-7 or MK-4 converted from MK-7. In this review, we comprehensively discuss the various properties of MK-7.

The effect of menaquinone-7 supplementation on vascular calcification in patients with diabetes: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Vitamin K occurs in the diet as phylloquinone and menaquinones. Observational studies have shown that both phylloquinone and menaquinone intake might reduce cardiovascular disease (CVD) risk. However, the effect of vitamin K on vascular calcification is unknown.

OBJECTIVES

The aim of this study was to assess if menaquinone supplementation, compared to placebo, decreases vascular calcification in people with type 2 diabetes and known CVD.

METHODS

In this double-blind, randomized, placebo-controlled trial, we randomly assigned men and women with type 2 diabetes and CVD to 360 µg/d menaquinone-7 (MK-7) or placebo for 6 mo. Femoral arterial calcification at baseline and 6 mo was measured with 18sodium fluoride positron emission tomography (18F-NaF PET) scans as target-to-background ratios (TBRs), a promising technique to detect active calcification. Calcification mass on conventional computed tomography (CT) scan was measured as secondary outcome. Dephosphorylated-uncarboxylated matrix Gla protein (dp-ucMGP) concentrations were measured to assess compliance. Linear regression analyses were performed with either TBR or CT calcification at follow-up as the dependent variable, and treatment and baseline TBR or CT calcification as independent variables.

RESULTS

We randomly assigned 35 patients to the MK-7 group (33 completed follow-up) and 33 to the placebo group (27 completed follow-up). After the 6-mo intervention, TBR tended to increase in the MK-7 group compared with placebo (0.25; 95% CI: -0.02, 0.51; P = 0.06), although this was not significant. Log-transformed CT calcification mass did not increase in the intervention group compared with placebo (0.50; 95% CI: -0.23, 1.36; P = 0.18). MK-7 supplementation significantly reduced dp-ucMGP compared with placebo (-205.6 pmol/L; 95% CI: -255.8, -155.3 pmol/L). No adverse events were reported.

CONCLUSION

MK-7 supplementation tended to increase active calcification measured with 18F-NaF PET activity compared with placebo, but no effect was found on conventional CT. Additional research investigating the interpretation of 18F-NaF PET activity is necessary. This trial was registered at clinicaltrials.gov as NCT02839044.

Engineering a Bifunctional Phr60-Rap60-Spo0A Quorum-Sensing Molecular Switch for Dynamic Fine-Tuning of Menaquinone-7 Synthesis in Bacillus subtilis

Quorum sensing (QS)-based dynamic regulation has been widely used as basic tool for fine-tuning gene expression in response to cell density changes without adding expensive inducers. However, most reported QS systems primarily relied on down-regulation rather than up-regulation of gene expression, significantly limiting its potential as a molecular switch to control metabolic flux. To solve this challenge, we developed a bifunctional and modular Phr60-Rap60-Spo0A QS system, based on two native promoters, P_abrB (down-regulation by Spo0A-P) and P_spoiiA (up-regulation by Spo0A-P). We constructed a library of promoters with different capacities to implement down-regulation and up-regulation by changing the location, number, and sequences of the binding sites for Spo0A-P. The QS system can dynamically balance the relationship between efficient synthesis of the target product and cell growth. Finally, we validated the usefulness of this strategy by dynamic control of menaquinone-7 (MK-7) synthesis in Bacillus subtilis 168, a model Gram-positive bacterium, with the bifunctional Phr60-Rap60-Spo0A quorum sensing system. Our dynamic pathway regulation led to a 40-fold improvement of MK-7 production from 9 to 360 mg/L in shake flasks and 200 mg/L in 15-L bioreactor. Taken together, our bilayer QS system has been successfully integrated with biocatalytic functions to achieve dynamic pathway regulation in B. subtilis 168, which may be extended for use in other microbes to fine-tune gene expression and improve metabolites production.

Metabolic Engineering of the MEP Pathway in Bacillus subtilis for Increased Biosynthesis of Menaquinone-7

Vitamin K is essential for blood coagulation and plays important roles in bone and cardiovascular health. Menaquinone-7 (MK-7) is one form of vitamin K that is especially useful due to its long half-life in the circulation. MK-7 is difficult to make via organic synthesis, and is thus commonly produced by fermentation. This study aimed to genetically modify Bacillus subtilis cultures to increase their MK-7 yield and reduce production costs. We constructed 12 different strains of B. subtilis 168 by overexpressing different combinations of the rate-limiting enzymes Dxs, Dxr, Idi, and MenA. We observed an 11-fold enhancement of production in the best-performing strain, resulting in 50 mg/L MK-7. Metabolite analysis revealed new bottlenecks in the pathway at IspG and IspH, which suggest avenues for further optimization. This work highlights the usefulness of Bacillus subtilis for industrial production of high value compounds.

Enhanced Vitamin K (Menaquinone-7) Production by Bacillus subtilis natto in Biofilm Reactors by Optimization of Glucose-based Medium

BACKGROUND

Benefits of vitamin K have been reported by many studies recently, due to its ability to reduce the risk of cardiovascular diseases and its potential benefits against osteoporosis. Specifically, menaquinone-7 (MK-7), being the most potent form of vitamin K, has definitely received most of the attention. Currently, solid or static liquid fermentation strategies are utilized for industrial production of MK-7 by Bacillus strains. However, these strategies face fundamental operational and scale-up issues as well as intense pellicle and biofilm formations which is problematic in static liquid fermentation, due to heat and mass transfer inefficiencies they create.

OBJECTIVE

The purpose of this study was to demonstrate that biofilm reactors will overcome the issues associated with suspended cell reactors when using Bacillus strains to produce MK-7. The expectation is that the use of biofilm reactors will result in a significant increase in the production of MK-7.

METHOD

Vitamin K production by Bacillus subtilis natto when grown in a biofilm reactor was evaluated at various concentrations of the three major nutrients, glucose, yeast extract and casein. The data was analyzed using response surface methodology (RSM).

RESULTS

The maximum concentration of MK-7 in the biofilm reactors was 20.5±0.5 mg/L, which was a 344 % increase when compared to the amount produced in suspended-cell reactors containing the same optimum media composition.

CONCLUSION

These results demonstrate the potential of utilizing biofilm reactors for MK-7 production on an industrial scale.

Modular Pathway Engineering of Bacillus subtilis To Promote De Novo Biosynthesis of Menaquinone-7

Menaquinone-7 (MK-7), a valuable vitamin K₂, plays an important role in the prevention of osteoporosis and cardiovascular calcification. We chose B. subtilis 168 as the chassis for the modular metabolic engineering design to promote the biosynthesis of MK-7. The biosynthetic pathway of MK-7 was categorized into four modules, namely, the MK-7 pathway (Module I), the shikimate (SA) pathway (Module II), the methylerythritol phosphate (MEP) pathway (Module III), and the glycerol metabolism pathway (Module IV). Overexpression of menA (Module I) resulted in 6.6 ± 0.1 mg/L of MK-7 after 120 h fermentation, which was 2.1-fold that of the starting strain BS168NU (3.1 ± 0.2 mg/L). Overexpression of aroA, aroD, and aroE (Module II) had a negative effect on the synthesis of MK-7. Simultaneous overexpression of dxs, dxr, yacM, and yacN (Module III) enabled the yield of MK-7 to 12.0 ± 0.1 mg/L. Moreover, overexpression of glpD (Module IV) resulted in an increase of the yield of MK-7 to 13.7 ± 0.2 mg/L. Furthermore, deletion of dhbB reduced the consumption of the intermediate metabolite isochorismate, thus promoting the yield of MK-7 to 15.4 ± 0.6 mg/L. Taken together, the final resulting strain MK3-MEP123-Gly2-Δ dhbB with simultaneous overexpression of menA, dxs, dxr, yacM-yacN, glpD and deletion of dhbB enabled the yield of MK-7 to 69.5 ± 2.8 mg/L upon 144 h fermentation in a 2 L baffled flask.

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.

Bicuspid Aortic Valve Stenosis and the Effect of Vitamin K2 on Calcification Using 18F-Sodium Fluoride Positron Emission Tomography/Magnetic Resonance: The BASIK2 Rationale and Trial Design

BASIK2 is a prospective, double-blind, randomized placebo-controlled trial investigating the effect of vitamin K2 (menaquinone-7;MK7) on imaging measurements of calcification in the bicuspid aortic valve (BAV) and calcific aortic valve stenosis (CAVS). BAV is associated with early development of CAVS. Pathophysiologic mechanisms are incompletely defined, and the only treatment available is valve replacement upon progression to severe symptomatic stenosis. Matrix Gla protein (MGP) inactivity is suggested to be involved in progression. Being a vitamin K dependent protein, supplementation with MK7 is a pharmacological option for activating MGP and intervening in the progression of CAVS. Forty-four subjects with BAV and mild-moderate CAVS will be included in the study, and baseline 18F-sodiumfluoride (18F-NaF) positron emission tomography (PET)/ magnetic resonance (MR) and computed tomography (CT) assessments will be performed. Thereafter, subjects will be randomized (1:1) to MK7 (360 mcg/day) or placebo. During an 18-month follow-up period, subjects will visit the hospital every 6 months, undergoing a second 18F-NaF PET/MR after 6 months and CT after 6 and 18 months. The primary endpoint is the change in PET/MR 18F-NaF uptake (6 months minus baseline) compared to this delta change in the placebo arm. The main secondary endpoints are changes in calcium score (CT), progression of the left ventricularremodeling response and CAVS severity (echocardiography). We will also examine the association between early calcification activity (PET) and later changes in calcium score (CT).

US Pharmacopeial Convention safety evaluation of menaquinone-7, a form of vitamin K

Vitamin K plays important biological roles in maintaining normal blood coagulation, bone mineralization, soft tissue physiology, and neurological development. Menaquinone-7 is a form of vitamin K2 that occurs naturally in some animal-derived and fermented foods. It is also available as an ingredient of dietary supplements. Menaquinone-7 has greater bioavailability than other forms of vitamin K, which has led to increasing sales and use of menaquinone-7 supplements. This special article reviews the chemistry, nomenclature, dietary sources, intake levels, and pharmacokinetics of menaquinones, along with the nonclinical toxicity data available and the data on clinical outcomes related to safety (adverse events). In conclusion, the data reviewed indicate that menaquinone-7, when ingested as a dietary supplement, is not associated with any serious risk to health or with other public health concerns. On the basis of this conclusion, US Pharmacopeia monographs have been developed to establish quality standards for menaquinone-7 as a dietary ingredient and as a dietary supplement in various dosage forms.

Inhibition of TNF-α, IL-1α, and IL-1β by Pretreatment of Human Monocyte-Derived Macrophages with Menaquinone-7 and Cell Activation with TLR Agonists In Vitro

Circulatory markers of low-grade inflammation such as tumor necrosis factor-alpha (TNF-α), interleukin-1 alpha (IL-1α), and interleukin-1 beta (IL-1β) positively correlate with endothelial damage, atheroma formation, cardiovascular disease, and aging. The natural vitamin K2-menaquinone-7 (MK-7) added to the cell culture of human monocyte-derived macrophages (hMDMs) at the same time as toll-like receptor (TLR) agonists did not influence the production of TNF-α. When the cells were pretreated up to 6 h with MK-7 before treatment with TLR agonists, MK-7 did not inhibit significantly the production of TNF-α after the TLR activation. However, 30 h pretreatment of hMDMs with at least 10 μM of MK-7 effectively and dose dependently inhibited the proinflammatory function of hMDMs. Pretreatment of hMDMs with 10 μM of MK-7 for 30 h resulted in 20% inhibition of TNF-α production after lipopolysaccharide (LPS) activation (P < .05) and 43% inhibition after macrophage-activating lipopeptide (MALP) activation (P < .001). Pathogen-associated molecular pattern (PMPP) activation was inhibited by 20% with MK-7 pretreatment; however, this inhibition was not statistically significant. The 30 h pretreatment of a THP-1-differentiated monocyte cell line with MK-7 resulted in a dose-dependent downregulation of TNFα, IL-1α, and IL-1β gene expression as evaluated by RNA semiquantitative reverse transcription polymerase chain reaction (RT-PCR). MK-7 is able to modulate immune and inflammatory reactions in the dose-response inhibition of TNF-α, IL-1α, and IL-1β gene expression and protein production by the healthy hMDMs in vitro.

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.

Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women. A double-blind randomised clinical trial

Observational data suggest a link between menaquinone (MK, vitamin K2) intake and cardiovascular (CV) health. However, MK intervention trials with vascular endpoints are lacking. We investigated long-term effects of MK-7 (180 µg MenaQ7/day) supplementation on arterial stiffness in a double-blind, placebo-controlled trial. Healthy postmenopausal women (n=244) received either placebo (n=124) or MK-7 (n=120) for three years. Indices of local carotid stiffness (intima-media thickness IMT, Diameter end-diastole and Distension) were measured by echotracking. Regional aortic stiffness (carotid-femoral and carotid-radial Pulse Wave Velocity, cfPWV and crPWV, respectively) was measured using mechanotransducers. Circulating desphospho-uncarboxylated matrix Gla-protein (dp-ucMGP) as well as acute phase markers Interleukin-6 (IL-6), high-sensitive C-reactive protein (hsCRP), tumour necrosis factor-α (TNF-α) and markers for endothelial dysfunction Vascular Cell Adhesion Molecule (VCAM), E-selectin, and Advanced Glycation Endproducts (AGEs) were measured. At baseline dp-ucMGP was associated with IMT, Diameter, cfPWV and with the mean z-scores of acute phase markers (APMscore) and of markers for endothelial dysfunction (EDFscore). After three year MK-7 supplementation cfPWV and the Stiffness Index βsignificantly decreased in the total group, whereas distension, compliance, distensibility, Young's Modulus, and the local carotid PWV (cPWV) improved in women having a baseline Stiffness Index β above the median of 10.8. MK-7 decreased dp-ucMGP by 50 % compared to placebo, but did not influence the markers for acute phase and endothelial dysfunction. In conclusion, long-term use of MK-7 supplements improves arterial stiffness in healthy postmenopausal women, especially in women having a high arterial stiffness.

Vitamin K: an old vitamin in a new perspective

The topic of "Vitamin K" is currently booming on the health products market. Vitamin K is known to be important for blood coagulation. Current research increasingly indicates that the antihaemorrhagic vitamin has a considerable benefit in the prevention and treatment of bone and vascular disease. Vitamin K1 (phylloquinone) is more abundant in foods but less bioactive than the vitamin K2 menaquinones (especially MK-7, menaquinone-7). Vitamin K compounds undergo oxidation-reduction cycling within the endoplasmic reticulum membrane, donating electrons to activate specific proteins via enzymatic gamma-carboxylation of glutamate groups before being enzymatically reduced. Along with coagulation factors (II, VII, IX, X, and prothrombin), protein C and protein S, osteocalcin (OC), matrix Gla protein (MGP), periostin, Gas6, and other vitamin K-dependent (VKD) proteins support calcium homeostasis, inhibit vessel wall calcification, support endothelial integrity, facilitate bone mineralization, are involved in tissue renewal and cell growth control, and have numerous other effects. The following review describes the history of vitamin K, the physiological significance of the K vitamers, updates skeletal and cardiovascular benefits and important interactions with drugs.

Safety assessment of menaquinone-7 for use in human nutrition

Vitamin K occurs widely in foods and has been shown to have a beneficial effect on the cardiovascular system, as well as anticancer, anti-inflammatory, and antiosteoporosis properties. A previous study indicates that long-chain menaquinone-7 may be more bioavailable than vitamin K and short-chain menaquinones. In the present study, acute, subacute toxicity and genotoxicity assays were carried out to evaluate the safety of oral menaquinone-7 in albino Wistar rats. Oral administration of menaquinone-7, at a concentration of 2000 mg/kg, did not cause toxic symptoms in either male or female rats. A subacute toxicity study also proved the safety and tolerance of prolonged treatment (for 90 days) with menaquinone-7 in rats, as evidenced by biochemical, hematological, and urine parameters as well as by histopathological analysis. Genotoxicity and mutagenicity studies were performed by comet, micronucleus, and Ames tests on Salmonella typhimurium strains, which showed cellular safety and nonmutagenicity of menaquinone-7. The results indicate the safety of menaquinone-7 for human consumption.

Effect of low-dose supplements of menaquinone-7 (vitamin K2 ) on the stability of oral anticoagulant treatment: dose-response relationship in healthy volunteers

BACKGROUND AND OBJECTIVE

Despite the worldwide use of vitamin K antagonists (VKAs), there is limited knowledge of the influence of dietary vitamin K on anticoagulation control. In view of the increasing nutraceutical availability of menaquinone-7 (MK-7; vitamin K2 ) and its promotion for bone and cardiovascular health, it is important to determine the posology for the interference of supplemental MK-7 with VKA therapy.

PATIENTS

Eighteen healthy men and women were anticoagulated for 4 weeks with acenocoumarol, and 15 of them attained a target International Normalized Ratio (INR) of 2.0. In the six subsequent weeks, subjects were given increasing doses of MK-7 (10, 20 and 45 μg day(-1) ) while continuing acenocoumarol treatment at established individual doses.

RESULTS

Apart from the INR, acenocoumarol treatment significantly increased the levels of uncarboxylated factor II (ucFII), uncarboxylated osteocalcin (ucOC), and desphospho-uncarboxylated matrix Gla-protein (dp-ucMGP), and decreased endogenous thrombin generation (ETP). A daily intake of 45 μg of MK-7 significantly decreased the group mean values of both the INR and ucFII by ~ 40%. Daily intakes of 10 and 20 μg of MK-7 were independently judged by two hematologists to cause a clinically relevant lowering of the INR in at least 40% and 60% of subjects, respectively, and to significantly increase ETP by ~ 20% and ~ 30%, respectively. Circulating ucOC and dp-ucMGP were not affected by MK-7 intake.

CONCLUSIONS

MK-7 supplementation at doses as low as 10 μg (lower than the usual retail dose of 45 μg) significantly influenced anticoagulation sensitivity in some individuals. Hence, the use of MK-7 supplements needs to be avoided in patients receiving VKA therapy.