Vitamin K and cardiovascular complications in CKD patients

Combating Methotrexate Resistance in Cancer Treatment: A Review on Navigating Pathways and Enhancing Its Efficacy With Fat-Soluble Vitamins

Methotrexate (MTX), a potent analogue and antagonist of folic acid, is a first-line treatment for rheumatoid arthritis, IBD and cancer. The development of MTX resistance contributes to the reduced efficacy and development of adverse reactions, forcing clinicians to withdraw treatment early. This drawback requires combinational approaches to combat the resistance and enhance the efficacy and safety of MTX. To provide a brief overview of MTX resistance and strategies to mitigate its aftereffects in cancer therapy, a literature-based search was conducted using keywords such as cancer pathology, MTX mechanism and resistance, S100A4, folate uptake, folate efflux, P-glycoprotein, beta-catenin and anticancer properties of Vitamins A, D, E and K. Investigations encompassing in vitro studies, in vivo studies and clinical trials were reviewed to identify the mechanisms of resistance induced by MTX and the potential benefits of coadministering fat-soluble vitamins with existing anticancer drugs. Derivates of Vitamin A could target cancer stem cells and increase chemotherapy sensitivity in non-small cell lung cancer. Similarly, calcitriol and cytotoxic medications exhibit additive or synergistic effects. Existing research revealed that fat-soluble vitamins can inhibit drug transporters, such as P-glycoprotein, which inhibit drug efflux, improving chemotherapy efficacy in cancer. As personalised medicine continues to evolve, incorporating combination approaches with MTX and fat-soluble vitamins holds promise for enhancing treatment efficacy, which can counteract MTX resistance via multiple pathways and improve the safety profile.

Development and Validation of a Rapid Liquid Chromatography-Tandem Mass Spectrometry Method for the Quantitation of Vitamin K Metabolites in Different Matrices

Adequate vitamin K is crucial for optimal health. Although vitamin K detection methods have been established using liquid chromatography-tandem mass spectrometry (LC-MS/MS), some limitations remain. Therefore, we aimed to establish a stable and rapid LC-MS/MS method that can quantify phylloquinone (VK1), menaquinones-4 (MK-4), and menaquinones-7 (MK-7) in serum and cerebrospinal fluid and explore its clinical applications. We developed an LC-MS/MS method with atmospheric pressure chemical ionization to quantify and validate its performance according to Clinical Laboratory and Standard Institution standards (C62-Ed2). Serums from 50 healthy individuals and cerebrospinal fluid from 15 patients were collected for clinical application. Sample preparation involved lipase incubation, protein precipitation with ethanol, and liquid-liquid extraction with hexane/ethyl; optimization was performed for sample preparation and LC separation. Linearity was 50-10 000 pg/mL for VK1, MK-4, and MK-7. The total coefficient of variation (%) for VK1, MK-4, and MK-7 ranged from 8.5% to 10.4%, 8.0% to 10.4%, and 7.0% to 11.1%, respectively. Recovery of VK1, MK-4, and MK-7 was 82.3%-110.6%, 92.3%-110.6%, and 89.5%-117.8%, respectively. VK1 and MK-7 were detected in the serum of all 50 healthy subjects, whereas MK-4 was detected in only 13 (26%) subjects. Approximately 53.3% (8/15) had no detectable vitamin K in their cerebrospinal fluid. The developed method exhibited satisfactory performance and was applicable for detecting VK1, MK-4, and MK-7 in serum and cerebrospinal fluid.

The role of vitamin K2 in cognitive impairment: linking vascular health to brain health

Cognitive impairment, marked by a decline in essential mental aspects such as attention, memory, and problem-solving, is significantly correlated with advancing age. This condition presents a major challenge for the elderly, adversely affecting quality of life, diminishing independence, and imposing substantial burdens on healthcare systems. Recent research indicates that vitamin K2 may be vital for preserving brain health and cognitive function. Traditionally recognized primarily for its role in blood coagulation, vitamin K has emerged in recent years as a nutrient with diverse biological effects essential for healthy aging. A growing body of evidence from both observational and interventional studies underscores the pivotal role of vitamin K2 in mitigating arterial calcification. This mechanism may link vascular health to cognitive function, suggesting that vitamin K2 could play a critical role in the prevention of cognitive impairment in aging populations.

Whole Blood Metabolomic Profiling of Mice with Tacrolimus-Induced Chronic Nephrotoxicity: NAD+ Depletion with Salvage Pathway Impairment

Tacrolimus (TAC)-induced chronic nephrotoxicity (TAC nephrotoxicity) is a serious issue for long-term graft survival in kidney transplantation. However, the pathophysiology of TAC nephrotoxicity remains unclear. In this study, we analyzed whole blood samples from mice that developed TAC nephrotoxicity in order to discover its mechanism. Mice were divided into a TAC group and a control group (n = 5 per group). The TAC group received TAC subcutaneously (1 mg/kg/day for 28 days), while the control group received normal saline instead. After the administration period, whole blood was collected and metabolomic analysis was performed, revealing significant changes in 56 metabolites. The major metabolic changes were related to uremic toxins, vascular damage, and NAD+. NAD+ levels were significantly lower in the TAC group, and ADP-ribose, nicotinamide, and nicotinamide N-oxide, which are degradation products of NAD+, were significantly higher, suggesting impairment of the NAD+ salvage pathway. NAD+ deficiency suggests cellular aging and mitochondrial dysfunction, which may induce vascular damage and chronic kidney disease. Our study demonstrated a correlation between low NAD+ levels and the pathophysiology of TAC nephrotoxicity.

Combating Methotrexate Resistance in Cancer Treatment: A Review on Navigating Pathways and Enhancing Its Efficacy With Fat‐Soluble Vitamins

Methotrexate (MTX), a potent analogue and antagonist of folic acid, is a first‐line treatment for rheumatoid arthritis, IBD and cancer. The development of MTX resistance contributes to the reduced efficacy and development of adverse reactions, forcing clinicians to withdraw treatment early. This drawback requires combinational approaches to combat the resistance and enhance the efficacy and safety of MTX. To provide a brief overview of MTX resistance and strategies to mitigate its aftereffects in cancer therapy, a literature‐based search was conducted using keywords such as cancer pathology, MTX mechanism and resistance, S100A4, folate uptake, folate efflux, P‐glycoprotein, beta‐catenin and anticancer properties of Vitamins A, D, E and K. Investigations encompassing in vitro studies, in vivo studies and clinical trials were reviewed to identify the mechanisms of resistance induced by MTX and the potential benefits of coadministering fat‐soluble vitamins with existing anticancer drugs. Derivates of Vitamin A could target cancer stem cells and increase chemotherapy sensitivity in non–small cell lung cancer. Similarly, calcitriol and cytotoxic medications exhibit additive or synergistic effects. Existing research revealed that fat‐soluble vitamins can inhibit drug transporters, such as P‐glycoprotein, which inhibit drug efflux, improving chemotherapy efficacy in cancer. As personalised medicine continues to evolve, incorporating combination approaches with MTX and fat‐soluble vitamins holds promise for enhancing treatment efficacy, which can counteract MTX resistance via multiple pathways and improve the safety profile.

Evaluation of Phylloquinone Content in 42 Species Algae Inhabiting the Japanese Coast and Relationship between Phylloquinone and Chlorophyll Contents

Terrestrial green plants are rich in phylloquinone (PK), and their PK content is highly correlated with the chlorophyll content. However, there are few studies on the PK content of algae and its correlation with chlorophyll content. To evaluate the PK content in algae and its correlation with chlorophyll, the PK and chlorophyll contents in algae, including Phaeophyta (18 species), Rhodophyta (17 species), and Chlorophyta (seven species), were determined. Algae, particularly Phaeophyta, contain more functional components than do other green terrestrial plants. Therefore, other components such as carotenoids, polyphenols, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability were analyzed to confirm their correlation with PK. Furthermore, terrestrial plants such as leafy vegetables, other vegetables, and tea powder were evaluated for the same components and compared with the experimental results for algae. This results showed that PK was abundant in Phaeophyta and almost all samples contained more than 100 μg/100 g of dry samples. In particular, Sargassum muticum contained 514.11±11.29 μg/100 g. However, almost all of the Rhodophyta and Chlorophyta contained a little PK. The results also confirmed a positive correlation between the PK and chlorophyll content in Rhodophyta (R2=0.7085), Chlorophyta (R2=0.7264), and terrestrial plants (R2=0.8436). However, no correlation was observed between the PK and chlorophyll content in Phaeophyta (R2=0.1013). In addition, the principal component analysis results showed no correlation between PK and other components, such as carotenoids and polyphenols, and DPPH radical scavenging ability in algae. However, Phaeophyta also contained more functional components, such as carotenoids, polyphenols, and DPPH radical scavenging ability than the other algal groups.

PIVKA-II but not dp-ucMGP is associated with aortic calcification in chronic kidney disease

BACKGROUND

Patients with chronic kidney disease (CKD) are susceptible to vascular calcification and vitamin K deficiency. Matrix gla protein (MGP) is a potent inhibitor of calcification requiring vitamin K for activation. Inactive MGP, i.e. dephosphorylated uncarboxylated MGP (dp-ucMGP), is frequently elevated in CKD along with protein induced by vitamin K absence (PIVKA-II). We investigated whether dp-ucMGP and PIVKA-II are useful markers of aortic calcification in CKD.

METHODS

Patients with normal or reduced kidney function underwent a non-contrast computed tomography scan of the entire aorta with subsequent blinded standard calcification scoring of the aortic wall ad modum Agatston. Blood samples were analyzed for plasma concentrations of dp-ucMGP and PIVKA-II.

RESULTS

141 patients (104 with CKD stage 3-5) were included. In patients with/without CKD median (interquartile range) were dp-ucMGP 543 (503-744)/1078 (835-1682) pmol/l (P < 0.01); PIVKA-II 19.3 (16.3-23.5)/21.8 (17.2-36.8) ng/ml (P = 0.33) and aortic Agatston scores 1644 (729-4138)/7172 (2834-15360) (P < 0.01). Agatston score was positively associated with PIVKA-II (β = 0.71, P = 0.014, r2 = 0.04) and tended to be so with dp-ucMGP (β = 0.44, P = 0.08, r2 = 0.02). Age, estimated glomerular filtration rate (eGFR) and smoking status were also associated with Agatston score and remained so, along with PIVKA-II, when adjusted for potential confounders. However, the association between age and aortic Agatston score was stronger than for PIVKA-II, eGFR and smoking-status.

CONCLUSION

Vitamin K deficiency, as estimated through PIVKA-II, but not dp-ucMGP, is weakly associated with aortic Agatston score. Yet, as markers of aortic calcification, both were outperformed substantially by age, and neither surpassed smoking nor eGFR.

CLINICALTRIALS

GOV IDENTIFIER

NCT04114695.

Beyond the Coagulation Cascade: Vitamin K and Its Multifaceted Impact on Human and Domesticated Animal Health

Vitamin K (VK) is an essential micronutrient impacting many systems in the body. This lipid-soluble vitamin is found in various plant and animal products and is absorbed via the lymphatic system. This biomolecule's importance to human health includes but is not limited to its promotion of brain, cardiovascular, bone, and immune functions. These biological properties are also necessary for maintaining domesticated animal health. The synergistic impact of both VK and vitamin D (VD) maximizes these health benefits, specifically for the circulatory and skeletal systems. This manuscript reviews VK's properties, molecular structures, nutrikinetics, mechanisms of action, daily requirements, safety in supplemental form, biomarkers used for its detection, and impacts on various organs. The purpose of synthesizing this information is to evaluate the potential uses of VK for the treatment or prevention of diseases.

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 Supplement Use in Patients With CKD: Worth the Pill Burden?

All vitamins play essential roles in various aspects of body function and systems. Patients with chronic kidney disease (CKD), including those receiving dialysis, may be at increased risk of developing vitamin deficiencies due to anorexia, poor dietary intake, protein energy wasting, restricted diet, dialysis loss, or inadequate sun exposure for vitamin D. However, clinical manifestations of most vitamin deficiencies are usually subtle or undetected in this population. Testing for circulating levels is not undertaken for most vitamins except folate, B12, and 25-hydroxyvitamin D because assays may not be available or may be costly to perform and do not always correlate with body stores. The last systematic review through 2016 was performed for the Kidney Disease Outcome Quality Initiative (KDOQI) 2020 Nutrition Guideline update, so this article summarizes the more recent evidence. We review the use of vitamins supplementation in the CKD population. To date there have been no randomized trials to support the benefits of any vitamin supplementation for kidney, cardiovascular, or patient-centered outcomes. The decision to supplement water-soluble vitamins should be individualized, taking account the patient's dietary intake, nutritional status, risk of vitamins deficiency/insufficiency, CKD stage, comorbid status, and dialysis loss. Nutritional vitamin D deficiency should be corrected, but the supplementation dose and formulation need to be personalized, taking into consideration the degree of 25-hydroxyvitamin D deficiency, parathyroid hormone levels, CKD stage, and local formulation. Routine supplementation of vitamins A and E is not supported due to potential toxicity. Although more trial data are required to elucidate the roles of vitamin supplementation, all patients with CKD should undergo periodic assessment of dietary intake and aim to receive various vitamins through natural food sources and a healthy eating pattern that includes vitamin-dense foods.

Randomized Controlled Clinical Trial of the Effect of Treatment with Vitamin K2 on Vascular Calcification in Hemodialysis Patients (Trevasc-HDK)

Introduction

Vitamin K deficiency among patients on hemodialysis (HD) affects the function of matrix GLA protein (MGP), a potent vitamin K-dependent inhibitor of vascular calcification (VC).

Methods

We conducted a single-center randomized controlled trial (RCT) on maintenance HD patients to examine if vitamin K2 supplementation can reduce progression of coronary artery calcification (CAC) over an 18-month study period. Patients were randomized to vitamin K2 group receiving menaquinone-7360 μg 3 times/wk or control group. The primary outcome was CAC scores at the end of the study period. The secondary outcomes were aortic valve calcification (AVC), carotid-femoral pulse wave velocity (cfPWV), aortic augmentation index (AIx), dephosphorylated undercarboxylated MGP (dp-ucMGP) levels, major adverse cardiac events (MACE), and vascular access events.

Results

Of the 178 patients randomized, follow-up was completed for 138 patients. The CAC scores between the 2 groups were not statistically different at the end of 18 months (relative mean difference [RMD] 0.85, 95% CI 0.55-1.31). The secondary outcomes did not differ significantly in AVC (RMD 0.82, 95% CI 0.34-1.98), cfPWV (absolute mean difference [AMD] 0.55, 95% CI -0.50 to 1.60), and AIx (AMD 0.13, 95% CI -3.55 to 3.80). Supplementation with vitamin K2 did reduce dp-ucMGP levels (AMD -86, 95% CI -854 to -117). The composite outcome of MACE and mortality was not statistically different between the 2 groups (Hazard ratio = 0.98, 95% CI 0.50-1.94).

Conclusion

Our study did not demonstrate a beneficial effect of vitamin K2 in reducing progression of VC in this population at the studied dose and duration.

The Pleiotropic Role of Vitamin K in Multimorbidity of Chronic Obstructive Pulmonary Disease

Although defined by the presence of airflow obstruction and respiratory symptoms, patients with chronic obstructive pulmonary disease (COPD) are characterized by multimorbidity. Numerous co-occurring conditions and systemic manifestations contribute to the clinical presentation and progression of COPD; however, underlying mechanisms for multimorbidity are currently not fully elucidated. Vitamin A and vitamin D have been related to COPD pathogenesis. Another fat-soluble vitamin, vitamin K, has been put forward to exert protective roles in COPD. Vitamin K is an unequivocal cofactor for the carboxylation of coagulation factors, but also for extra-hepatic proteins including the soft tissue calcification inhibitor matrix Gla-protein and the bone protein osteocalcin. Additionally, vitamin K has been shown to have anti-oxidant and anti-ferroptosis properties. In this review, we discuss the potential role of vitamin K in the systemic manifestations of COPD. We will elaborate on the effect of vitamin K on prevalent co-occurring chronic conditions in COPD including cardiovascular disorders, chronic kidney disease, osteoporosis, and sarcopenia. Finally, we link these conditions to COPD with vitamin K as a connecting factor and provide recommendations for future clinical studies.

Effect of vitamin K on wound healing: A systematic review and meta-analysis based on preclinical studies

Background: In recent years, many studies have found that vitamin K is beneficial to wound healing. However, some research results seem to be in conflict. The purpose of this study was to evaluate the effect of vitamin K on wound healing.

Methods: We systematically and comprehensively searched the PubMed, Web of Science, Embase, Cochrane library, China National Knowledge Infrastructure (CNKI), VIP and Wanfang eletronic databases. We applied revman5.3 software to calculate the weighted mean difference (WMD) of 95% confidence interval (CI) of animal and cell groups to evaluate the effect of vitamin K on wound healing. Two researchers independently selected studies and used the Cochrane Collaboration tool to assess the risk of bias in the included studies. The overall quality of evidence was assessed using the Recommendation, Assessment, Development and Evaluation (GRADE) working group approch.

Results: Among the 1081 articles searched, 6 articles (16 studies in total) met the inclusion criteria. The results of quantitative analysis showed that vitamin K was beneficial to increase the wound healing rate in animal models [rat model: WMD = 27.45 (95% CI: 13.46, 41.44); p = 0.0001], but the opposite result was obtained in cell experiments [WMD = −33.84 (95% CI: −56.90, −10.79); p = 0.004].

Conclusion: This meta-analysis hits that vitamin K could affect the process of wound healing, especially in animal models. While we could not know the clear role at present, which requires larger scale research. In addition, the concentration and safe dose of vitamin K also deserve further study.

Dysbiosis in Patients with Chronic Kidney Disease: Let Us Talk About Vitamin K

PURPOSE OF REVIEW

This narrative review aimed to summarize the current evidence on the connection between dysbiosis and vitamin K deficiency in patients with chronic kidney disease (CKD). The presence of dysbiosis (perturbations in the composition of the microbiota) has been described in several non-communicable diseases, including chronic kidney disease, and it has been hypothesized that dysbiosis may cause vitamin K deficiency. Patients with CKD present both vitamin K deficiency and gut dysbiosis; however, the relationship between gut dysbiosis and vitamin K deficiency remains to be addressed.

RECENT FINDINGS

Recently, few studies in animals have demonstrated that a dysbiotic environment is associated with low production of vitamin K by the gut microbiota. Vitamin K plays a vital role in blood coagulation as well as in the cardiovascular and bone systems. It serves as a cofactor for γ-glutamyl carboxylases and thus is essential for the post-translational modification and activation of vitamin K-dependent calcification regulators, such as osteocalcin, matrix Gla protein, Gla-rich protein, and proteins C and S. Additionally, vitamin K executes essential antioxidant and anti-inflammatory functions. Dietary intake is the main source of vitamin K; however, it also can be produced by gut microbiota. This review discusses the effects of uremia on the imbalance in gut microbiota, vitamin K-producing bacteria, and vitamin K deficiency in CKD patients, leading to a better understanding and raising hypothesis for future clinical studies.

The association of renal impairment with different patterns of intracranial arterial calcification: Intimal and medial calcification

BACKGROUND AND AIMS

Increasing knowledge about calcification together with improved imaging techniques provided evidence that intracranial arterial calcification (IAC) can be divided into two distinct entities: intimal and medial calcification. The purpose of this study was to investigate the association between kidney function and the two patterns of IAC, which could clarify the underlying mechanisms of intimal or medial calcification and its clinical consequence.

METHODS

A total of 516 participants were enrolled in this study. Kidney function was assessed using the estimated glomerular filtration rate (eGFR) based on modified glomerular filtration rate estimating equation. The degree of IAC measured by IAC scores was evaluated on non-contrast head computed tomography (CT) images and IAC was classified as intimal or medial calcification. Associations of kidney function with IAC scores and patterns were assessed sing multivariate logistic regression analysis.

RESULTS

In 440 patients (85.27%) with IAC, 189 (42.95%) had predominant intimal calcifications and 251 (57.05%) had predominant medial calcifications. Multivariate analysis revealed that lower eGFR level (eGFR <60 ml/min/1.73 m²) was associated with higher IAC scores (odds ratio [OR] 2.01; 95% confidence interval [CI], 1.50-2.71; p < 0.001). Medial calcification was more frequent in the lower eGFR group (eGFR <60 ml/min/1.73 m²) compared to the other two groups with eGFR 60 to 89 and eGFR >90 ml/min/1.73 m² (78.72% vs. 53.65%, p < 0.001; 78.72% vs. 47.78%, p < 0.001). In multivariable analysis, impaired kidney function was associated with an increased odds of medial calcification presence in patients with eGFR <60 ml/min/1.73 m² (OR, 1.47; 95% CI, 1.05 to 2.06).

CONCLUSIONS

Our findings demonstrated that impaired renal function was independently associated with a higher degree of calcification in intracranial arteries, especially medial calcification, which reflects a distinction between two types of arterial calcification and raise the possibility for specific prevention of lesion formation.

Vitamin K antagonists and cardiovascular calcification: A systematic review and meta-analysis

Background

Many patients treated with Vitamin K antagonists (VKA) for anticoagulation have concomitant vascular or valvular calcification. This meta-analysis aimed to evaluate a hypothesis that vascular and valvular calcification is a side-effect of VKA treatment.

Methods

We conducted a systematic literature search to identify studies that reported vascular or valvular calcification in patients treated with VKA. The associations between VKA use and calcification were analyzed with random-effects inverse variance models and reported as odds ratios (OR) and 95% confidence intervals (95% CI). In addition, univariate meta-regression analyses were utilized to identify any effect moderators.

Results

Thirty-five studies were included (45,757 patients; 6,251 VKA users). The median follow-up was 2.3 years [interquartile range (IQR) of 1.2–4.0]; age 66.2 ± 3.6 years (mean ± SD); the majority of participants were males [77% (IQR: 72–95%)]. VKA use was associated with an increased OR for coronary artery calcification [1.21 (1.08, 1.36), p = 0.001], moderated by the duration of treatment [meta-regression coefficient B of 0.08 (0.03, 0.13), p = 0.0005]. Extra-coronary calcification affecting the aorta, carotid artery, breast artery, and arteries of lower extremities, was also increased in VKA treated patients [1.86 (1.43, 2.42), p < 0.00001] and moderated by the author-reported statistical adjustments of the effect estimates [B: −0.63 (−1.19, −0.08), p = 0.016]. The effect of VKA on the aortic valve calcification was significant [3.07 (1.90, 4.96), p < 0.00001]; however, these studies suffered from a high risk of publication bias.

Conclusion

Vascular and valvular calcification are potential side effects of VKA. The clinical significance of these side effects on cardiovascular outcomes deserves further investigation.

Vitamin K1 inhibits ferroptosis and counteracts a detrimental effect of phenprocoumon in experimental acute kidney injury

Ferroptosis, a type of iron-dependent programmed cell death distinct from apoptosis, necroptosis, and other types of cell death, is characterized by lipid peroxidation, reactive oxygen species production, and mitochondrial dysfunction. Accumulating evidence has highlighted vital roles for ferroptosis in multiple diseases, including acute kidney injury. Therefore, ferroptosis has become a major focus for translational research. However, despite its involvement in pathological conditions, there are no pharmacologic inhibitors of ferroptosis in clinical use. In the context of drug repurposing, a strategy for identifying new uses for approved drugs outside the original medical application, we discovered that vitamin K1 is an efficient inhibitor of ferroptosis. Our findings are strengthened by the fact that the vitamin K antagonist phenprocoumon significantly exacerbated ferroptotic cell death in vitro and also massively worsened the course of acute kidney injury in vivo, which is of utmost clinical importance. We therefore assign vitamin K1 a novel role in preventing ferroptotic cell death in acute tubular necrosis during acute kidney injury. Since the safety, tolerability, pharmacokinetics, and pharmacodynamics of vitamin K1 formulations are well documented, this drug is primed for clinical application, and provides a new strategy for pharmacological control of ferroptosis and diseases associated with this mode of cell death.

Updated Pathways in Cardiorenal Continuum after Kidney Transplantation

Cardiovascular disease (CVD) remains one of the leading causes for increased morbidity and mortality in chronic kidney disease (CKD). Kidney transplantation is the preferred treatment option for CKD G5. Improved perioperative and postoperative care, personalized immunosuppressive regimes, and refined matching procedures of kidney transplants improves cardiovascular health in the early posttransplant period. However, the long-term burden of CVD is considerable. Previously underrecognized, the role of the complement system alongside innate immunity, inflammaging, structural changes in the glomerular filtration barrier and early vascular ageing also seem to play an important role in the posttransplant management. This review provides up-to-date knowledge on these pathways that may influence the cardiovascular and renal continuum and identifies potential targets for future therapies. Arterial destiffening strategies and the applicability of sodium-glucose cotransporter 2 inhibitors and their role in cardiovascular health after kidney transplantation are also addressed.

Altered vitamin K biodistribution and metabolism in experimental and human chronic kidney disease

Chronic kidney disease (CKD) is accompanied with extensive cardiovascular calcification, in part correlating with functional vitamin K deficiency. Here, we sought to determine causes for vitamin K deficiency beyond reduced dietary intake. Initially, vitamin K uptake and distribution into circulating lipoproteins after a single administration of vitamin K1 plus K2 (menaquinone 4 and menaquinone 7, respectively) was determined in patients on dialysis therapy and healthy individuals. The patients incorporated very little menaquinone 7 but more menaquinone 4 into high density lipoprotein (HDL) and low-density lipoprotein particles than did healthy individuals. In contrast to healthy persons, HDL particles from the patients could not be spiked with menaquinone 7 in vitro and HDL uptake was diminished in osteoblasts. A reduced carboxylation activity (low vitamin K activity) of uremic HDL particles spiked with menaquinone 7 vs. that of controls was confirmed in a bioassay using human primary vascular smooth muscle cells. Kidney menaquinone 4 tissue levels were reduced in 5/6-nephrectomized versus sham-operated C57BL/6 mice after four weeks of a vitamin K rich diet. From the analyzed enzymes involved in vitamin K metabolism, kidney HMG-CoA reductase protein was reduced in both rats and patients with CKD. In a trial on the efficacy and safety of atorvastatin in 1051 patients with type 2 diabetes receiving dialysis therapy, no pronounced vitamin K deficiency was noted. However, the highest levels of PIVKA-II (biomarker of subclinical vitamin K deficiency) were noted when a statin was combined with a proton pump inhibitor. Thus, profound disturbances in lipoprotein mediated vitamin K transport and metabolism in uremia suggest that menaquinone 7 supplementation to patients on dialysis therapy has reduced efficacy.