Vitamin D analogs modulate the expression of plasminogen activator inhibitor-1, thrombospondin-1 and thrombomodulin in human aortic smooth muscle cells

Vitamin D Status in Patients with Primary Antiphospholipid Syndrome (PAPS): A Systematic Review and Meta-Analysis

Primary antiphospholipid syndrome (PAPS) is a systemic autoimmune disorder, characterised by consistently high levels of antiphospholipid antibodies, thrombosis, and/or pregnancy morbidity. Due to various suspected causes, deficient or insufficient levels of vitamin D in the serum have been reported in patients with PAPS; however, the reports have been sporadic and inconclusive. This systematic review and meta-analysis aimed to comprehensively evaluate the serum vitamin D levels in patients with PAPS compared to controls. A protocol was registered in PROSPERO (Registration No. CRD42019132128) and a systematic literature search was conducted through Google Scholar, PubMed, Web of Science, Scopus, and ScienceDirect databases without restricting language and year. Pooled prevalence, mean difference (MD), and odds ratio (OR) along with 95% confidence intervals (CI) were determined by using a random effects model. Study quality was assessed by the Joana Brigg's Institute (JBI) protocol and publication bias was evaluated by a trim and fill funnel plot, Begg's, and Egger's tests. The pooled prevalence of vitamin D deficiency and insufficiency was found to be 32.2% [95% CI: 16.3-48.2] and 61.5% [95% CI: 40.2-82.8], respectively. Serum levels of vitamin D were considerably lower in the PAPS patients compared to controls (MD: -5.75, 95% CI: -9.73 to -1.77; p = 0.005). Multiple sensitivity analyses showed that the results remained statistically significant, demonstrating the robustness of this meta-analysis. No significant publication bias was detected in determining the MD of serum vitamin D levels in PAPS and controls. In conclusion, PAPS patients had greater rates of vitamin D deficiency or insufficiency, higher frequency of thrombosis, and lower serum vitamin D levels than healthy individuals.

Association of amino acids and parameters of bone metabolism with endothelial dysfunction and vasculopathic changes in limited systemic sclerosis

Objectives

Pathways contributing to endothelial dysfunction in patients with limited cutaneous systemic sclerosis (lcSSc) are largely unknown. The aim of this study was to investigate potential associations of amino acids and parameters of bone metabolism with endothelial dysfunction and vasculopathy-related changes in patients with lcSSc and early-stage vasculopathy.

Methods

Amino acids, calciotropic parameters, including 25-hydroxyvitamin D and parathyroid hormone (PTH), and bone turnover parameters, including osteocalcin and N-terminal peptide of procollagen-3 (P3NP), were measured in 38 lcSSc patients and 38 controls. Endothelial dysfunction was assessed by biochemical parameters, pulse-wave analysis, flow-mediated and nitroglycerine-mediated dilation. Additionally, vasculopathy-related and SSc-specific clinical changes including capillaroscopic, skin, renal, pulmonary, gastrointestinal and periodontal parameters were recorded.

Results

No significant differences in amino acids, calciotropic and bone turnover parameters were observed between lcSSc patients and controls. In patients with lcSSc, several significant correlations were found between selected amino acids, parameters of endothelial dysfunction, vasculopathy-related and SSc-specific clinical changes (all with p < 0.05). In addition, significant correlations were observed between PTH and 25-hydroxyvitamin D with homoarginine, and between osteocalcin, PTH and P3NP with modified Rodnan skin score and selected periodontal parameters (all with p < 0.05). Vitamin D deficiency defined as 25-hydroxyvitamin D < 20 ng/ml was associated with the presence of puffy finger (p = 0.046) and early pattern (p = 0.040).

Conclusion

Selected amino acids may affect endothelial function and may be associated to vasculopathy-related and clinical changes in lcSSc patients, while the association with parameters of bone metabolism seems to be minor.

Impact of vitamin D on the prognosis after spinal cord injury: A systematic review

Vitamin D (VitD) insufficiency is a worldwide health problem and affects billions of people. Spinal cord injury (SCI) patients seem more susceptible to developing suboptimal levels of VitD. However, the literature regarding its impact on the prognosis of SCI is limited. Thus, in this review, we systematically investigated the published studies via a combination of keywords associated with SCI and VitD in four medical databases (Medline, Embase, Scopus, and Web of Science). All included studies were analyzed, and selected clinical data on the prevalence of VitD insufficiency (serum 25-hydroxyvitamin D < 30 ng/ml) and deficiency (serum 25-hydroxyvitamin D < 20 ng/ml) were collected for further meta-analysis via random effects. Through literature review, a total of 35 studies were eligible and included. The meta-analysis of VitD status (13 studies, 1,962 patients) indicated high prevalence of insufficiency (81.6% [75.7, 87.5]) and deficiency (52.5% [38.1, 66.9]) after SCI. Besides, low levels of VitD were reported to be associated with a higher risk of skeletal diseases, venous thromboembolism, psychoneurological syndromes, and chest illness after injury. Existing literature suggested that supplemental therapy might act as an adjuvant treatment to facilitate post-injury rehabilitation. Non-human experimental studies highlighted the neuroprotective effect of VitD, which was associated with enhancing axonal and neuronal survival, suppressing neuroinflammation, and modulating autophagy. Therefore, the current evidence suggests that the prevalence of VitD insufficiency is high in the SCI population, and low-level VitD may impair functional restoration after SCI. VitD supplemental treatment may have potential benefits to accelerate rehabilitation in mechanistically related processes after SCI. However, due to the limitation of the available evidence, more well-designed randomized controlled trials and mechanism experimental research are still needed to validate its therapeutic effect, elucidate its neuroprotective mechanism, and develop novel treatments.

Vitamin D Deficiency is Associated With Increased Plasminogen Activator Inhibitor 1/Plasminogen Activator Inhibitor 2 Ratio in Pregnancy

BACKGROUND

Vitamin D deficiency has recently been suggested as an independent risk factor for thrombosis. Notably, vitamin D deficiency is common in pregnant populations, whom already have an increased thrombotic risk. However, pregnant women are commonly excluded from studies investigating the hemostatic system, and knowledge on the impact of vitamin D on hemostasis in pregnancy is therefore limited.

METHODS

A cross-sectional study comparing the hemostatic profile of pregnant women (gestational week 12.9 ± 0.7) with vitamin D deficiency (≤50 nmol/L) (n = 70) and high adequate vitamin D status (≥100 nmol/L) (n = 59).

RESULTS

Vitamin D deficient women displayed increased plasminogen activator inhibitor 1 levels and an increased plasminogen activator inhibitor 1/plasminogen activator inhibitor 2 ratio, even after adjusting for factors with potential influence on hemostasis (body mass index, smoking and use of fish oil supplements).

CONCLUSIONS

Vitamin D deficiency is associated with increased plasminogen activator inhibitor 1/plasminogen activator inhibitor 2 ratio in pregnant women. As an increased plasminogen activator inhibitor 1/plasminogen activator inhibitor 2 ratio with high plasminogen activator inhibitor 1 levels may increase thrombotic risk and is associated with the development of pregnancy complications, further research is needed to determine the optimal vitamin D supplementation in pregnancy.

Is Vitamin D Deficiency Prothrombotic? A Systematic Review

Observational studies indicate a relationship between vitamin D deficiency and an increased risk of venous and arterial thrombotic events, but the underlying mechanisms behind this association are uncertain. This systematic review explores if there is an association between decreased vitamin D levels and a prothrombotic profile. The systematic literature search initially identified 3,214 studies (published until December 21, 2021) investigating the relationship between vitamin D and numerous hemostatic parameters. After the screening process, 18 observational and intervention studies fulfilled the inclusion criteria and were included in this systematic review. Parameters of primary hemostasis, secondary hemostasis, and fibrinolysis were investigated in six, thirteen, and fifteen of these studies, respectively. Most of the eligible studies did not identify significant associations between decreased vitamin D levels and hemostatic parameters. Some conflicting results were found between decreased vitamin D levels and thrombin generation parameters and the tissue factor pathway inhibitor. Conflicting results were also found between decreased vitamin D levels and fibrinolytic parameters, although the evidence may point toward weak associations with some regulators of fibrinolysis, mostly decreased tissue type plasminogen activator. Overall, our systematic review did not identify any definitive link between vitamin D deficiency and a prothrombotic profile, which might otherwise help explain the observed association between vitamin D deficiency and increased risk of thrombotic events. Moreover, there is no clinical evidence to confirm or refute a possible antithrombotic effect of vitamin D. Larger high-quality randomized controlled trials are needed to better elucidate the link between vitamin D deficiency and a prothrombotic risk profile.

A comprehensive look into the association of vitamin D levels and vitamin D receptor gene polymorphism with obesity in children

Childhood obesity accounts for several psychosocial and clinical consequences. Psychosocial consequences include lower self-esteem, social isolation, poor academic achievement, peer problems, and depression, whereas clinical consequences are cardiovascular diseases, type 2 diabetes, dyslipidemia, cancer, autoimmune diseases, girls early polycystic ovarian syndrome (PCOS), asthma, bone deformities, etc. A growing number of studies have uncovered the association of childhood obesity and its consequences with vitamin-D (vit-D) deficiency and vitamin-D receptor (VDR) gene polymorphisms such as single nucleotide polymorphisms (SNPs), e.g., TaqI, BsmI, ApaI, FokI, and Cdx2. Considering the impact of vit-D deficiency and VDR gene polymorphisms, identifying associated factors and risk groups linked to lower serum vit-D levels and prevention of obesity-related syndromes in children is of utmost importance. Previously published review articles mainly focused on the association of vit-D deficiency with obesity or other non-communicable diseases in children. The nature of the correlation between vit-D deficiency and VDR gene polymorphisms with obesity in children is yet to be clarified. Therefore, this review attempts to delineate the association of obesity with these two factors by identifying the molecular mechanism of the relationship.

The Role of Vitamin D in the Relationship Between Gender and Deep Vein Thrombosis Among Stroke Patients

Introduction: Accumulating evidence had demonstrated that females had a higher risk of deep vein thrombosis (DVT) than males, but the mechanism was still unknown. Vitamin D was found to play an essential role in DVT, and gender may influence the serum vitamin D levels. This study aimed to explore whether vitamin D played a role in the gender difference in DVT.

Materials and Methods: A total of 444 patients with acute stroke were recruited, which were divided into the DVT group (n = 222) and the non-DVT group (n = 222). Serum vitamin D levels were measured after admission and were split into three categories, including deficiency (<50 nmol/L), insufficiency (52.5–72.5 nmol/L), and sufficiency (more than 75 nmol/L). Hierarchical regression analysis was adopted to analyze the relationship between gender and DVT, controlling the confounding factors.

Results: Females showed a higher proportion of DVT than males (60.7 vs. 42.5%, p < 0.001), and lower serum vitamin D levels than males (53.44 ± 16.45 vs. 69.43 ± 23.14, p < 0.001). Moreover, serum vitamin D levels were lower in the DVT group than in the non-DVT group (59.44 ± 19.61 vs. 66.24 ± 23.86, p < 0.001). Besides, the DVT group showed a lower proportion of vitamin D sufficiency than the non-DVT group (21.2 vs. 32.9%, p < 0.05). Hierarchical regression analysis showed that females had 2.083-fold (p < 0.001, unadjusted model) and 1.413-fold (p = 0.155, adjusted model) risk to develop DVT. In addition, the sufficiency status of vitamin D showed an independent protective effect on DVT (unadjusted model OR, 0.504, p = 0.004; adjusted model OR, 0.686, p = 0.011).

Conclusion: Females had a higher risk of DVT than males, and vitamin D may play an essential role in this relationship. Further studies are needed to explore whether vitamin D supplementation could reduce DVT risk in stroke patients, especially females.

Vitamin D levels and oxidative stress markers in patients hospitalized with COVID-19

Background

COVID-19 is characterized by the presence of oxidative stress. Vitamin D status has been reviewed as one of the factors that may affect disease severity. The aim of this study was to assess the relationship between serum vitamin D levels, oxidative stress markers and disease severity in hospitalized COVID-19 patients.

Methods

Vitamin D levels were measured in 33 patients with COVID-19. The total antioxidant power and plasma peroxides were determined in serum.

Results

Severe COVID-19 patients have lower vitamin D levels (18.39 ± 2.29 ng/mL vs. 28.47 ± 3.05 ng/mL, p < .05) and higher oxidative stress compared to the moderate group. When divided according to serum vitamin D levels, significantly higher values of LDH (604.8 ± 76.98 IU/mL vs. 261.57 ± 47.33 IU/mL) and D-dimer (5978 ± 2028ng/mL vs. 977.7 ± 172 ng/mL) were obtained in the group with vitamin D below 30 ng/mL, followed with significantly higher levels of plasma peroxides (d-ROMs: 414.9 ± 15.82 U.Carr vs. 352.4 ± 18.77 U.Carr; p < .05) and oxidative stress index (OSI: 92.25 ± 6.60 vs. 51.89 ± 6.45; p < .001).

Conclusion

The presented data provide a justification to consider vitamin D as an important factor that could ameliorate disease severity through its anti-inflammatory and antioxidant effects.

Vitamin D levels and C-reactive protein/albumin ratio in pregnant women with cerebral venous sinus thrombosis

Changes in coagulation system during pregnancy have been put forth as risk factors for cerebral venous sinus thrombosis (CVT), yet we still have limited knowledge on markers for predicting the risk of CVT in pregnant women. Therefore, we aimed to investigate the significance of vitamin D (VD) levels and C-reactive protein (CRP)/albumin ratio (CAR), an inflammation marker, as risk factors for CVT in pregnant women. 23 pregnant women who were followed up for CVT, 26 healthy pregnant women who had no pregnancy complications, and 31 non-pregnant fertile women were included in the study. CAR and VD levels were compared between groups. CAR was significantly higher in the pregnant CVT group compared to the other two groups (p < 0.001). CAR was also significantly higher in the healthy pregnant group than the non-pregnant fertile group (p < 0.001). VD levels were determined to be statistically significantly lower in the pregnant CVT group compared to the other two groups (p < 0.001). However, VD levels did not significantly differ between healthy pregnant group and non-pregnant fertile group (p > 0.05). We found no significant correlation between CAR and VD levels in any of the three groups. Pregnant women with CVT were found to have a high rate of severe VD deficiency. Low VD levels and high CAR levels in pregnant women may be associated with an increased risk of CVT.

Does Evidence Exist to Blunt Inflammatory Response by Nutraceutical Supplementation during COVID-19 Pandemic? An Overview of Systematic Reviews of Vitamin D, Vitamin C, Melatonin, and Zinc

More than one year has passed since the first cases of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome (SARS)-CoV-2 coronavirus were reported in Wuhan (China), rapidly evolving into a global pandemic. This infectious disease has become a major public health challenge in the world. Unfortunately, to date, no specific antivirals have been proven to be effective against COVID-19, and although a few vaccines are available, the mortality rate is not decreasing but is still increasing. One therapeutic strategy has been focused on infection prevention and control measures. In this regard, the use of nutraceutical supports may play a role against some aspect of the infection, particularly the inflammatory state and the immune system function of patients, thus representing a strategy to control the worst outcomes of this pandemic. For this reason, we performed an overview including meta-analyses and systematic reviews to assess the association among melatonin, vitamin C, vitamin D, zinc supplementation and inflammatory markers using three databases, namely, MEDLINE, PubMed Central and the Cochrane Library of Systematic Reviews. According to the evidence available, an intake of 50,000 IU/month of vitamin D showed efficacy in CRP. An amount of 1 to 2 g per day of vitamin C demonstrated efficacy both in CRP and endothelial function, and a dosage of melatonin ranging from 5 to 25 mg /day showed good evidence of efficacy in CRP, TNF and IL6. A dose of 50 mg/day of elemental zinc supplementation showed positive results in CRP. Based on the data reported in this review, the public health system could consider whether it is possible to supplement the current limited preventive measures through targeted nutraceutical large-scale administration.

Improving the endothelial dysfunction in type 2 diabetes with chromium and vitamin D3 byreducing homocysteine and oxidative stress: A randomized placebo-controlled trial

BACKGROUND

Chromium picolinate (CrPic) and vitamin D3 are known as two antioxidant micronutrients. Through inducing endothelial dysfunction, oxidants such as homocysteine (Hct) and malondialdehyde (MDA) lead to cardiovascular disease in type 2 diabetes mellitus (T2DM). No published data has directly examined the effects of these two antioxidants on improving the endothelial dysfunction in T2DM throughreducing homocysteine and oxidative stress.

METHODS

Subjects (n = 92) in this randomized, double blind, placebo-control study were randomly assigned to receive oral placebo (group I), D₃ (group II: 50,000 IU/ week), chromium picolinate (CrPic) (group III: 500 μg/day), and both vitamin D₃ and CrPic (group IV) for four months. Fasting blood samples were drawn at study baseline and following intervention to determine Hct, MDA, total antioxidant capacity (TAC), total thiol groups (SHs), vascular cell adhesion molecule- 1 (VCAM-1), and plasminogen activator inhibitor-1 (PAI-1).

RESULTS

After intervention, MDA significantly decreased in groups II and IV; TAC significantly increased in group IV, and SHs significantly augmented in group III; Hct was significantly reduced in groups II, III, and IV; and VCAM-1 significantly decreased in groups III and IV and PAI-1 was significantly reduced in groups II, III, and IV.

CONCLUSION

Our findings suggest that through reducing homocysteine and oxidative stress and improving endothelial dysfunction, chromium and vitamin D₃ co-supplementation might be predictive and preventive of cardiovascular diseasesassociated with T2DM. IRCT, IRCT20190610043852N1, registered 21 October 2019, https://fa.irct.ir/user/trial/42293/view.

Association between serum vitamin D levels and venous thromboembolism (VTE): A systematic review and meta-analysis of observational studies

OBJECTIVE

Although many studies have attempted to unravel the relationship between vitamin D deficiency and the incidence of VTE, the results remained inconsistent. To address this discrepancy, we performed a systematic review and meta-analysis to precisely disentangle the relationship between serum vitamin D levels and VTE risk.

METHODS

The Web of Science, Scopus, PubMed/Medline, Embase, and Google Scholar databases were searched for all available observational studies that reported the risk of venous thromboembolism (VTE) based on serum vitamin D levels categories. The search was performed up to March 2020.

RESULTS

Seven studies were included. The overall analysis showed a significantly increased risk of VTE in subjects with low levels of serum vitamin D compared with those with normal vitamin D levels (RR = 1.34; 95% CI: 1.07-1.69; P = 0.011). In a sensitivity analysis, we did not observe a significant effect of any individual study on the combined effect sizes. Nevertheless, significant heterogeneity was present among the studies (Cochrane Q test, p = 0.018, I² = 61%). In the stratified analysis, low vitamin D levels were positively associated with an increased risk of VTE in prospective population-based studies (RR = 1.31; 95% CI: 1.06-1.61; P = 0.010) and in subjects below 60 years old (RR = 1.28; 95% CI: 1.07-1.54; P = 0.060).

CONCLUSION

our systematic review and meta-analysis showed that a low serum vitamin D level was indeed associated with an increased risk of VTE.

Vitamin D and cardiovascular disorders

Vitamin D is necessary for bone health but may also have many extra-skeletal effects. The vitamin D endocrine system has major effects on gene and protein expression in many cells and tissues related to the cardiovascular system. In addition, many preclinical studies in animals with vitamin D deficiency or genetically silenced expression of the vitamin D receptor or vitamin D metabolizing enzymes suggest that the absence of vitamin D action may result in cardiovascular events. This includes dysfunctions of endothelial cells, thereby accelerating the process of atherosclerosis, hypertension or abnormal coagulation, ultimately resulting in higher risks for all major cardiovascular or cerebrovascular events. A wealth of observational studies in different parts of the world have fairly consistently found a strong association between a poor vitamin D status and surrogate markers or hard cardiovascular events. A few Mendelian randomization studies did, however, not find a link between genetically lower serum 25OHD concentrations and cardiovascular events. Finally, many RCTs could not demonstrate a consistent effect on surrogate markers, and a limited number of RCTs did so far not find whatever effect on hard cardiovascular endpoints such as myocardial ischemia or infarction, stroke, or cardiovascular death. In conclusion, preclinical data generated a plausible hypothesis of a link between vitamin D status and extra-skeletal events, including cardiovascular endpoints. Whether the vitamin D endocrine system is redundant for the human vascular system or whether the RCTs have not been optimally designed to answer the research question is thus not yet settled.

Role of Vitamin D Status in Diabetic Patients with Renal Disease

Diabetes mellitus (DM) poses a major public health problem worldwide, with ever-increasing incidence and prevalence in recent years. The Institute for Alternative Futures (IAF) expects that the total number of people with type 1 and type 2 DM in the United States will increase by 54%, from 19,629,000 to 54,913,000 people, between 2015 and 2030. Diabetic Nephropathy (DN) affects about one-third of patients with DM and currently ranks as the first cause of end-stage kidney disease in the Western world. The complexity of interactions of Vitamin D is directly related with progressive long-term changes implicated in the worsening of renal function. These changes result in a dysregulation of the vitamin D-dependent pathways. Various studies demonstrated a pivotal role of Vitamin D supplementation in regression of albuminuria and glomerulosclerosis, contrasting the increase of glomerular basement membrane thickening and podocyte effacement, with better renal and cardiovascular outcomes. The homeostasis and regulation of the nephron’s function are absolutely dependent from the cross-talk between endothelium and podocytes. Even if growing evidence proves that vitamin D may have antiproteinuric, anti-inflammatory and renoprotective effects in patients with DN, it is still worth investigating these aspects with both more in vitro studies and randomized controlled trials in larger patient series and with adequate follow-up to confirm the effects of long-term vitamin D analogue supplementation in DN and to evaluate the effectiveness of this therapy and the appropriate dosage.

Nucleic Acid Therapies for Ischemic Stroke

Stroke remains a leading cause of disability and death worldwide despite significant scientific and therapeutic advances. Therefore, there is a critical need to improve stroke prevention and treatment. In this review, we describe several examples that leverage nucleic acid therapeutics to improve stroke care through prevention, acute treatment, and recovery. Aptamer systems are under development to increase the safety and efficacy of antithrombotic and thrombolytic treatment, which represent the mainstay of medical stroke therapy. Antisense oligonucleotide therapy has shown some promise in treating stroke causes that are genetically determined and resistant to classic prevention approaches such as elevated lipoprotein (a) and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Targeting microRNAs may be attractive because they regulate factors involved in neuronal cell death and reperfusion-associated injury, as well as neurorestorative pathways. Lastly, microRNAs may aid reliable etiologic classification of stroke subtypes, which is important for effective secondary stroke prevention.

Venous Thromboembolism is Associated With Lack of Vitamin D Supplementation in Patients With Spinal Cord Injury and Low Vitamin D Levels

BACKGROUND

The role of vitamin D in the pathogenesis of venous thromboembolism (VTE) and prevalence of low vitamin D (LVitD) in spinal cord injury (SCI) has motivated vitamin D testing and supplementation. This is an exploratory study of data collected at a time before the routine clinical practice of vitamin D supplementation, allowing for evaluation of the natural history of vitamin D levels in patients with SCI.

OBJECTIVE

To determine if vitamin D supplementation in persons with SCI and LVitD levels is associated with decreased prevalence of VTE.

DESIGN

Retrospective cohort study.

SETTING

Rehabilitation Center at a Level I Trauma Center.

PARTICIPANTS

Patients with SCI admitted to acute inpatient rehabilitation (N = 282).

MAIN OUTCOME MEASURES

VTE prevalence in patients with LVitD levels, grouped by presence or absence of vitamin D supplementation.

RESULTS

Of the acute inpatient SCI population, 80% (227/282) of patients demonstrated vitamin D levels <30 ng/mL (LVitD). Although the incidence of VTE was almost double in the LVitD group, 19% (43/227) of the patients in the LVitD group had VTE versus 9% (5/55) of patients with vitamin D levels ≥30 ng/mL (normal VitD [NVitD]); this difference was not statistically significant (P = .108, Cramer's V = .104). When the role of vitamin D supplementation was analyzed, individuals in the LVitD group who received no vitamin D supplementation (LVitDSuppNegative) had a higher incidence of VTE (statistically significant) compared to the LVitD group with vitamin D supplementation (LVitDSuppPositive) (24% [42/178] vs. 2% [1/49]) (P < .001, Cramer's V = .226). In post hoc exploratory analyses, the VTE rate of patients in the LVitDSuppNegative group was noted to be significantly higher than that in all other patient groups combined (P < .001, Cramer's V = .229). A binary logistic regression model incorporating clinical covariates also showed this grouping to be significant.

CONCLUSION

A significant association appears to exist between lack of vitamin D supplementation and VTE occurrence in persons with acute SCI and LVitD levels.

LEVEL OF EVIDENCE

III.

Low Vitamin D Levels Are Associated With the Development of Deep Venous Thromboembolic Events in Patients With Ischemic Stroke

The objective is to determine whether a low serum 25-hydroxyvitamin D (25(OH)D) level is associated with an increased incidence of deep venous thromboembolic events in patients with ischemic stroke. One hundred eighty persons admitted consecutively for inpatient rehabilitation at the Department of Rehabilitation of the First Affiliated Hospital of Wenzhou Medical University with a diagnosis of ischemic stroke from January 2015 to December 2015 were enrolled. The following demographic data were collected: age, sex, body mass index, and history of risk factors. The levels of 25(OH)D and the presence of deep vein thrombosis (DVT) by routine duplex imaging were also recorded. The value of 25(OH)D needed to predict DVT was analyzed using logistic regression analysis, after adjusting for the possible confounders. We found that 80% of patients admitted to the acute inpatient rehabilitation unit had low levels of vitamin D. Forty-seven patients had DVT, and the incidence of DVT was 26.1% within 3 weeks after the stroke event. With all patients taken together, DVT occurrence as a dependent variable with the sufficient group as the reference used for vitamin D levels in the logistic analysis, deficiency of vitamin D was independently associated with the development of DVT (odds ratio = 4.683, 95% confidence interval: 1.396-15.703, P = .012). In conclusion, low serum 25(OH)D levels were independent predictors of DVT in patients with ischemic stroke during inpatient rehabilitation stay in China. This finding reveals the critical role played by 25(OH)D in the pathogenesis of DVT.

Role of Vitamin D Beyond the Skeletal Function: A Review of the Molecular and Clinical Studies

The classical function of Vitamin D, which involves mineral balance and skeletal maintenance, has been known for many years. With the discovery of vitamin D receptors in various tissues, several other biological functions of vitamin D are increasingly recognized and its role in many human diseases like cancer, diabetes, hypertension, cardiovascular, and autoimmune and dermatological diseases is being extensively explored. The non-classical function of vitamin D involves regulation of cellular proliferation, differentiation, apoptosis, and innate and adaptive immunity. In this review, we discuss and summarize the latest findings on the non-classical functions of vitamin D at the cellular/molecular level and its role in complex human diseases.

Non-skeletal health effects of vitamin D supplementation: A systematic review on findings from meta-analyses summarizing trial data

BACKGROUND

A large number of observational studies have reported harmful effects of low 25-hydroxyvitamin D (25OHD) levels on non-skeletal outcomes. We performed a systematic quantitative review on characteristics of randomized clinical trials (RCTs) included in meta-analyses (MAs) on non-skeletal effects of vitamin D supplementation.

METHODS AND FINDINGS

We identified systematic reviews (SR) reporting summary data in terms of MAs of RCTs on selected non-skeletal outcomes. For each outcome, we summarized the results from available SRs and scrutinized included RCTs for a number of predefined characteristics. We identified 54 SRs including data from 210 RCTs. Most MAs as well as the individual RCTs reported null-findings on risk of cardiovascular diseases, type 2 diabetes, weight-loss, and malignant diseases. Beneficial effects of vitamin D supplementation was reported in 1 of 4 MAs on depression, 2 of 9 MAs on blood pressure, 3 of 7 MAs on respiratory tract infections, and 8 of 12 MAs on mortality. Most RCTs have primarily been performed to determine skeletal outcomes, whereas non-skeletal effects have been assessed as secondary outcomes. Only one-third of the RCTs had low level of 25OHD as a criterion for inclusion and a mean baseline 25OHD level below 50 nmol/L was only present in less than half of the analyses.

CONCLUSIONS

Published RCTs have mostly been performed in populations without low 25OHD levels. The fact that most MAs on results from RCTs did not show a beneficial effect does not disprove the hypothesis suggested by observational findings on adverse health outcomes of low 25OHD levels.

Plasminogen Activator Inhibitor Type-1 as a Regulator of Fibrosis

Fibrosis is known as a frequent and irreversible pathological condition which is associated with organ failure. Tissue fibrosis is a central process in a variety of chronic progressive diseases such as diabetes, hypertension, and persistent inflammation. This state could contribute to chronic injury and the initiation of tissue repair. Fibrotic disorders represent abnormal wound healing with defective matrix turnover and clearance that lead to excessive accumulation of extracellular matrix components. A variety of identified growth factors, cytokines, and persistently activated myofibroblasts have critical roles in the pathogenesis of fibrosis. Irrespective of etiology, the transforming growth factor-β pathway is the major driver of fibrotic response. Plasminogen activator inhibitor-1 (PAI-1) is a crucial downstream target of this pathway. Transforming growth factor-β positively regulates PAI-1 gene expression via two main pathways including Smad-mediated canonical and non-canonical pathways. Overexpression of PAI-1 reduces extracellular matrix degradation via perturbing the plasminogen activation system. Indeed, elevated PAI-1 levels inhibit proteolytic activity of tissue plasminogen activator and urokinase plasminogen activator which could contribute to a variety of inflammatory elements in the injury site and to excessive matrix deposition. This review summarizes the current knowledge of critical pathways that regulate PAI-1 gene expression and suggests effective approaches for the treatment of fibrotic disease. J. Cell. Biochem. 119: 17-27, 2018. © 2017 Wiley Periodicals, Inc.

Vitamin D supplementation lowers thrombospondin-1 levels and blood pressure in healthy adults

INTRODUCTION

Vitamin D insufficiency, defined as 25-hydroxyvitamin D (25(OH)D) levels < 75nmol/L is associated with cardio-metabolic dysfunction. Vitamin D insufficiency is associated with inflammation and fibrosis, but it remains uncertain whether these anomalies are readily reversible. Therefore, we aimed to determine the effects of vitamin D supplementation on markers of: 1) nitric oxide (NO) signaling, 2) inflammation, and 3) fibrosis, in healthy volunteers with mild hypovitaminosis.

METHODS

Healthy volunteers (n = 35) (mean age: 45 ± 11 years) with 25(OH)D levels <75nmol/L, received vitamin D supplementation (Ostelin ® capsules 2000IU) for 12 weeks. Resting systolic and diastolic blood pressures (BP) were assessed. Routine biochemistry was examined. Plasma concentrations of asymmetric dimethylarginine (ADMA), thrombospondin-1 (TSP-1), plasminogen activator inhibitor-1 (PAI-1), hs-CRP, activin-A, and follistatin-like 3 (FSTL3) were quantitated.

RESULTS

Vitamin D administration for 12 weeks significantly increased 25-(OH)D levels (48.8 ± 16 nmol/L to 100.8 ± 23.7 nmol/L, p<0.001). There was significant lowering of systolic and diastolic BP, while there was no significant change in lipid profiles, or fasting insulin. Plasma concentrations of ADMA, hs-CRP, PAI-1, activin A, and FSTL-3 did not change with vitamin D supplementation. However, there was a marked reduction of TSP-1 (522.7 ± 379.8 ng/mL vs 206.7 ± 204.5 ng/mL, p<0.001).

CONCLUSIONS

Vitamin D supplementation in vitamin D insufficient, but otherwise healthy individuals markedly decreased TSP-1 levels and blood pressure. Since TSP-1 suppresses signaling of NO, it is possible that the fall in BP is engendered by restoration of NO effect.

Effectiveness of Vitamin D Supplementation for Cardiovascular Health Outcomes

There is a plausible physiological theory, supported by many observational studies, that vitamin D supplementation should be effective for improving cardiovascular end points, such as blood pressure (BP), large artery stiffness, atherosclerosis, endothelial function and clinical events. However, results from randomised controlled trials (RCTs) have been inconsistent. In this review, we evaluated the evidence regarding the effectiveness of vitamin D supplementation for cardiovascular surrogate and hard clinical end points. RCTs were assessed in terms of sample size, duration of supplementation, baseline vitamin D level inclusion criteria (i.e., absence of vitamin D deficiency), dosage of vitamin D and population under investigation. Forty-five RCTs were identified. Eight RCTs with BP and 6 RCTs with large artery stiffness as the end points were found to comply with guidelines for the optimal design of clinical trials evaluating nutrient effects. Only 2 of the RCTs with an optimal design were effective in decreasing BP with vitamin D supplementation, although these were of moderate sample size (<150) and very short duration (8 weeks for both), whilst no RCT was effective in reducing large artery stiffness. Similar results were observed for atherosclerotic and endothelial function markers as end points. Only 1 RCT reported cardiovascular events as an end point and found neither increased nor decreased incident cardiovascular events over 7 years of follow-up. In conclusion, results from published RCTs indicate that vitamin D supplementation is ineffective in improving cardiovascular health among various patient populations, including in the presence or absence of vitamin D deficiency.

Serum phosphate modifies the vascular response to vitamin D receptor activation in chronic kidney disease (CKD) patients

BACKGROUND AND AIMS

Vitamin D receptor activation (VDRA) ameliorates endothelial dysfunction in CKD patients but also increases phosphate and FGF-23, which may attenuate the beneficial effect of VDRA on endothelial function.

METHODS AND RESULTS

This is a pre-specified secondary analysis of the PENNY trial (NCT01680198) testing the effect of phosphate and FGF-23 on the flow mediated vasodilatory (FMD) response to paricalcitol (PCT, 2 μg/day) and placebo over a 12-weeks treatment period. Eighty-eight stage G3-4 CKD patients were randomized to PCT (n = 44) and Placebo (n = 44). Endothelial function was assessed by measuring endothelium dependent forearm blood flow (FBF) response to ischemia. The FMD response was by the 61% higher in PCT treated patients than in those on placebo (P = 0.01). Phosphate (+11%, P = 0.039), calcium (+3%, P = 0.01) and, particularly so, FGF23 (+164%, P < 0.001) increased in PCT treated patients. Changes in FMD by PCT associated inversely with phosphate (r = -0.37, P = 0.01) but were independent of FGF-23, calcium and PTH changes. The response to PCT was maximal in patients with no changes in phosphate (1st tertile), attenuated in those with mild-to-moderate rise in phosphate (2nd tertile) and abolished in those with the most pronounced phosphate increase (3rd tertile) (effect modification P = 0.009). No effect modification by FGF-23 and other variables was observed.

CONCLUSIONS

The beneficial effect of PCT on endothelial function in CKD is maximal in patients with no or minimal changes in phosphate and it is abolished in patients with a pronounced phosphate rise. These findings generate the hypothesis that the endothelium protective effect by VDRA may be potentiated by phosphate lowering interventions.

Associations of Serum 25-Hydroxyvitamin D With Hemostatic and Inflammatory Biomarkers in the Multi-Ethnic Study of Atherosclerosis

CONTEXT

Mechanisms explaining documented associations of 25-hydroxyvitamin D [25(OH)D] deficiency with increased risks of cardiovascular disease (CVD) and venous thromboembolism may relate to adverse hemostatic and inflammatory responses.

OBJECTIVE

To evaluate whether 25(OH)D deficiency is associated with a prothrombotic and proinflammatory biological profile.

DESIGN

Cross-sectional analyses.

SETTING

The Multi-Ethnic Study of Atherosclerosis, a multicenter prospective cohort of American adults.

PARTICIPANTS

Up to 6554 adults free of CVD.

MAIN OUTCOME MEASURES

Ten hemostatic biomarkers (D-dimer, fibrinogen, factor VIII, plasmin-antiplasmin, and homocysteine [n = 6443]; von Willebrand factor, soluble tissue factor, plasminogen activator inhibitor-1 (PAI-1), total tissue factor pathway inhibitor (TFPI), and soluble thrombomodulin [n = 814]), and three inflammatory biomarkers (IL-6, C-reactive protein [n = 6443], and TNF-α soluble receptor [n = 3802]).

RESULTS

Among 6443 subjects (46.6% men; mean age, 62.1 years; mean body mass index, 28.3 kg/m(2)) of White (37.8%), Black (27.2%), Chinese (12.2%), and Hispanic (21.8%) race/ethnicity, mean 25(OH)D was 25.3 ng/mL. After multiple adjustment, 25(OH)D concentrations were associated with concentrations of IL-6 and homocysteine and also with concentrations of PAI-1 and TFPI: per 10 ng/mL decrement in 25(OH)D, 5.1% higher IL-6 (95% confidence interval [CI], 3.4-6.9; P < .001); 3.7% higher homocysteine (95% CI, 3.0-4.3; P < .001); 7.0% higher PAI-1 (95% CI, 0.9-13.6; P = .025); and 2.1% higher TFPI (95% CI, 0.0-4.2; P = .047), without racial/ethnic heterogeneity. No significant associations were observed for other hemostatic and inflammatory biomarkers.

CONCLUSIONS

Increased inflammation as reflected by higher circulating IL-6 and increased homocysteine concentrations may represent mechanisms linking 25(OH)D deficiency to greater risks of CVD and perhaps venous thromboembolism. Low concentrations of 25(OH)D were also associated with PAI-1 and TFPI concentrations, but not with other hemostatic biomarkers.

Serum levels of 25(OH)D are not associated with venous thromboembolism in the elderly population. A case-control study

The prevalence of both vitamin D deficiency and venous thromboembolism (VTE) is important in the elderly. Previous studies have provided evidence for a possible association between vitamin D status and the risk of VTE. Thus, we aimed to investigate the association between vitamin D levels and VTE in the population aged 75 and over included in the EDITH case-control study. The association between vitamin D status and VTE was analysed. We also analysed the monthly and seasonal variations of VTE and vitamin D. Between May 2000 and December 2009, 340 elderly patients (mean age 81.5 years, 32% men) with unprovoked VTE and their controls were included. The univariate and multivariate analysis found no significant association between serum levels of vitamin D and the risk of unprovoked VTE. In the unadjusted analysis, a higher BMI was statistically associated with an increased risk of VTE (OR 1.09; 95% CI 1.05-1.13) whereas a better walking capacity and living at home were associated with a decreased rate of VTE: OR 0.57; 95% CI 0.36-0.90 and 0.40; 95% CI 0.25-0.66, respectively. Although not significant, more VTE events occurred during winter (p=0.09). No seasonal variations of vitamin D levels were found (p=0.11). In conclusion, in contrast with previous reports our findings suggest that vitamin D is not associated with VTE in the elderly population.

Low Serum Vitamin D Is Independently Associated with Larger Lesion Volumes after Ischemic Stroke

BACKGROUND

Despite its high prevalence, known association with vascular disease and stroke incidence and fatality, little is known about the contribution of vitamin D status to a worse outcome after ischemic stroke. Therefore, we sought to assess whether low serum 25-hydroxyvitamin D (25[OH]D), a marker of vitamin D status, is predictive of the ischemic infarct volume and whether it relates to a worse outcome.

METHODS

We retrospectively analyzed prospective, consecutive acute ischemic stroke patients evaluated from January 2013 to January 2014 at a tertiary referral center. All patients (n = 96) had a magnetic resonance imaging-proven acute ischemic stroke. Multivariable linear and logistic regression analyses were used to test whether vitamin D represents an independent predictor of infarct volume and poor 90-day outcome (modified Rankin Scale score of >2).

RESULTS

In univariable analyses, lacunar infarct etiology, lower admission National Institutes of Health Stroke Scale, and higher serum 25(OH)D concentration were associated with smaller infarct volumes (P < .05). The association of 25(OH)D with ischemic infarct volume was independent of other known predictors of the infarct extent (P = .001). Multivariable analyses showed that the risk for a poor 90-day outcome doubled with each 10-ng/mL decrease in serum 25(OH)D.

CONCLUSIONS

Low serum 25(OH)D was independently associated with larger ischemic infarct volume, which may partially explain observed worse outcomes in ischemic stroke patients with poor vitamin D status. Although causality remains to be proven, our results provide the rationale to further explore vitamin D as a promising marker for cerebral ischemic vulnerability and to identify stroke patients at high risk for poor outcome.

Vitamin D and diabetic nephropathy: A systematic review and meta-analysis

OBJECTIVE

There has been a long history documenting the use of different vitamin D derivatives as therapy for renal diseases. However, to our knowledge, there is no comprehensive assessment of the relation between vitamin D deficiency and risk for diabetic nephropathy (DN). Additionally, the effect of vitamin D supplementation on DN is still unclear. The aim of this meta-analysis was to assess these issues by pooling together the results from cross-sectional studies and clinical trials.

METHODS

A systematic literature search of PubMed, Scopus, and Google Scholar was conducted, ending in September 2014. For cross-sectional studies, odds ratio was used as a measure of the association between vitamin D status and risk for DN; for clinical trials, mean and SD of the main outcome (urine albumin-to-creatinine ratio [UACR]) in intervention and placebo groups were considered for analysis.

RESULTS

The final selected articles were published between 2009 and 2014. In all, 3700 and 219 patients were enrolled in observational and interventional studies, respectively. The pooled odds ratio from six cross-sectional studies was 1.80 (95% confidence interval [CI], 1.25-2.59; P = 0.002), indicating a significant inverse association between serum vitamin D status and risk for nephropathy in patients with diabetes. However, the pooled data of UACR levels in clinical trials suggested no significant change following vitamin D supplementation (17.98; 95% CI, -35.35 to 71.32; P = 0.51).

CONCLUSION

This meta-analysis showed the higher risk for nephropathy in vitamin D-deficient patients with diabetes. Pooling the results of available clinical trials after vitamin D supplementation did not support causality in this association.

Effect of long term vitamin D supplementation on biomarkers of inflammation in Latino and African-American subjects with pre-diabetes and hypovitaminosis D

Low vitamin D levels are associated with minority subjects, the metabolic syndrome, and inflammation. The effect of vitamin D supplementation on markers of inflammation has not been well studied. The aim of the study was to evaluate the effects of high doses of vitamin D supplementation for 1 year on serum biomarkers of inflammation in Latino and African-American subjects with pre-diabetes and hypovitaminosis D. Latino (n=69) and African-American (n=11) subjects who had both pre-diabetes and hypovitaminosis D with a mean age of 52.0 years, a BMI of 32.7 kg/m(2), and 70% of whom were females, were randomized to receive weekly doses (mean±SD) of vitamin D (85 300 IU±16 000) or placebo oil for 1 year. Serum levels of interleukin-6, tumor necrosis factor, highly sensitive C-reactive protein), plasminogen activator inhibitor 1, and insulin-like growth factor-1 were measured at baseline, 6, and 12 months. Serum 25-OH vitamin D levels of 22 ng/ml at baseline quickly rose to nearly 70 ng/ml in subjects receiving vitamin D and did not change in the placebo group. Two-way repeated measures ANOVA showed no differences between the 2 groups in any of the 5 selected parameters. High dose vitamin D supplementation for 1 year in minority subjects with pre-diabetes and hypovitaminosis D failed to affect serum biomarkers of inflammation.Clinical trial reg. no.: NCT00876928, clinicaltrials.gov.

Potential of vitamin D in treating diabetic cardiomyopathy

Cardiovascular disease is the leading cause of morbidity and mortality in patients with diabetes mellitus (DM), and patients with DM frequently develop diabetic cardiomyopathy. Currently, effective treatments for diabetic cardiomyopathy are limited. Vitamin D exerts pleiotropic effects on the cardiovascular system and is associated with DM. The purpose of this review was to evaluate published research on vitamin D in diabetic cardiomyopathy by searching PubMed databases. Herein, we reviewed vitamin D metabolism; evaluated the molecular, cellular, and neuroendocrine effects in native and bioactive vitamin D; and evaluated the role of vitamin D in treating cardiovascular disease and DM. Some evidence suggests that vitamin D may improve cardiovascular outcomes in diabetes through anti-inflammatory, antioxidative, antihypertrophic, antifibrotic, and antiatherosclerotic activities and by regulating advanced glycation end-product signaling, the renin-angiotensin system, and cardiac metabolism. This clinical and laboratory evidence suggests that vitamin D may be a potential agent in treating diabetic cardiomyopathy. However, using vitamin D entails possible adverse risks of hypercalcemia, hyperphosphatemia, and vascular calcifications. Therefore, future studies should be conducted that clarify the potential benefits of vitamin D through large-scale randomized clinical trials in well-defined groups of diabetic patients.

The Effect of Vitamin D Supplementation on Thrombin Generation Assessed by the Calibrated Automated Thrombogram

Observational and in vitro studies suggest that vitamin D may have antithrombotic activity. This study aimed to examine the relationship between vitamin D supplementation and thrombin generation. Serum 25-hydroxyvitamin D (25(OH)D) and thrombin generation parameters were measured in 73 healthy volunteers. Participants with serum 25(OH)D <50 nmol/L (n = 53) were treated with vitamin D3and tested for 25(OH)D and thrombin generation at the end of treatment. Lag time and time to peak decreased after treatment by a mean of -0.49 ± 0.51 minute (P< .001) and -0.76 ± 0.70 minute (P< .001), respectively, whereas endogenous thrombin potential and peak height increased after treatment by a mean of 170.1 ± 339.8 nmol/L minute (P= .001) and 34.2 ± 47.8 nmol/L (P< .001), respectively. Treatment with vitamin D supplementation seems to have prothrombotic effect in patients with vitamin D insufficiency. These findings should be interpreted with caution and need to be replicated in future studies.

Calcitriol reduces thrombospondin-1 and increases vascular endothelial growth factor in breast cancer cells: implications for tumor angiogenesis

Calcitriol, a potent antineoplastic vitamin D metabolite, inhibits proliferation, induces apoptosis and slows the growth of tumors. Calcitriol also may exert either antiangiogenic or proangiogenic effects depending on the tissue. Vascular endothelial growth factor (VEGF) and thrombospondin-1 (Tsp-1) are key factors involved in promoting and inhibiting angiogenesis, respectively. The effects of calcitriol on Tsp-1 have not been studied in the mammary gland, while VEGF regulation is not clear, since opposite outcomes have been demonstrated. Therefore, the present study was undertaken to investigate the effects of calcitriol on VEGF and Tsp-1 expression in primary breast tumor-derived cells and a panel of established breast cancer cell lines. In vivo studies in athymic mice were also performed in order to gain further insight into the biological effects of calcitriol on angiogenesis. Real time-PCR and ELISA analyses showed that calcitriol stimulated VEGF mRNA expression and protein secretion while elicited the opposite effect on Tsp-1 in 7 out of 8 cell lines studied, independently of the cell phenotype (P<0.05 in n=5). In vivo, calcitriol significantly inhibited the relative tumoral volume after 4 weeks of treatment; however, serum VEGF was higher in calcitriol-treated animals compared to controls (P<0.05). The integrated fluorescence intensity analysis of CD31, a vessel marker, showed that xenografted breast cancer cells developed tumors with similar vascular density regardless of the treatment. Nevertheless, larger necrotic areas were observed in the tumors of calcitriol-treated mice compared to controls. Since the antineoplastic activity of calcitriol has been consistently demonstrated in several studies including this one, our results suggest that the antitumoral effect of calcitriol in vivo involve different mechanisms not necessarily related to the inhibition of tumor vascularization. Overall, our findings indicate that calcitriol can impact the angiogenic process in breast cancer by regulating VEGF and Tsp-1 expression. This article is part of a Special Issue entitled '16th Vitamin D Workshop'.

The relationship between vitamin D status and idiopathic lower-extremity deep vein thrombosis

Background

Vitamin D has been shown to have an anticoagulant effect. A decrease in 25-hydroxyvitamin D [25(OH)D] concentration has also been associated with an increased risk of venous thromboembolism. Hence, we sought to determine the relationship between 25(OH) D levels and idiopathic lower-extremity deep vein thrombosis (DVT).

Methods

In a case control study, a total of 82 participants with idiopathic lower-extremity DVT were enrolled along with 85 sex- and age-matched healthy participants as controls. The plasma 25(OH)D levels were measured in all the studied samples.

Results

The participants’ mean age was 47.1±12.3 years. Baseline characteristics were not significantly different between the groups. The concentration of 25(OH)D was significantly lower in the DVT group compared to that of the control group (17.9±10.3 versus 23.1±12.5 ng/mL, P=0.004). The prevalence of participants with deficient 25(OH)D levels was significantly higher in the both DVT and control groups than those with sufficient 25(OH)D levels (68.3% versus 13.4%, and 49.4% versus 28.2%, respectively, P=0.027). In a multivariate analysis, 25(OH)D levels and sex were found to be the only independent predictors of DVT (odds ratio [OR] 1.05, 95% confidence interval [CI] 1.02–1.08, P=0.001 and OR 0.51, 95% CI 0.26–1.00, P=0.049, respectively).

Conclusion

Low levels of 25(OH)D are associated with idiopathic lower-extremity DVT. Further investigation is needed to establish determinants and probable causative role of 25(OH)D.

Potential pathophysiological role for the vitamin D deficiency in essential hypertension

Vitamin D deficiency has been indicated as a pandemic emerging public health problem. In addition to the well-known role on calcium-phosphorus homeostasis in the bone, vitamin D-mediated processes have been recently investigated on other diseases, such as infections, cancer and cardiovascular diseases. Recently, both the discovery of paracrine actions of vitamin D (recognized as “local vitamin D system”) and the link of vitamin D with renin-angiotensin-aldosterone system and the fibroblast growth factor 23/klotho pathways highlighted its active cardiovascular activity. Focusing on hypertension, this review summarizes the more recent experimental evidence involving the vitamin D system and deficiency in the cardiovascular pathophysiology. In particular, we updated the vascular synthesis/catabolism of vitamin D and its complex interactions between the various endocrine networks involved in the regulation of blood pressure in humans. On the other hand, the conflicting results emerged from the comparison between observational and interventional studies emphasize the fragmentary nature of our knowledge in the field of vitamin D and hypertension, strongly suggesting the need of further researches in this field.

Vitamin D and cardiovascular disease

Vitamin D plays a classical hormonal role in skeletal health by regulating calcium and phosphorus metabolism. Vitamin D metabolites also have physiological functions in nonskeletal tissues, where local synthesis influences regulatory pathways via paracrine and autocrine mechanisms. The active metabolite of vitamin D, 1α,25-dihydroxyvitamin D, binds to the vitamin D receptor that regulates numerous genes involved in fundamental processes of potential relevance to cardiovascular disease, including cell proliferation and differentiation, apoptosis, oxidative stress, membrane transport, matrix homeostasis, and cell adhesion. Vitamin D receptors have been found in all the major cardiovascular cell types including cardiomyocytes, arterial wall cells, and immune cells. Experimental studies have established a role for vitamin D metabolites in pathways that are integral to cardiovascular function and disease, including inflammation, thrombosis, and the renin-angiotensin system. Clinical studies have generally demonstrated an independent association between vitamin D deficiency and various manifestations of degenerative cardiovascular disease including vascular calcification. However, the role of vitamin D supplementation in the management of cardiovascular disease remains to be established. This review summarizes the clinical studies showing associations between vitamin D status and cardiovascular disease and the experimental studies that explore the mechanistic basis for these associations.

Very high-dose cholecalciferol and arteriovenous fistula maturation in ESRD: a randomized, double-blind, placebo-controlled pilot study

PURPOSE

While vitamin D is critical for optimal skeletal health, it also appears to play a significant role in vascular homeostasis. This pilot study compared arteriovenous (AV) access outcomes following cholecalciferol supplementation compared to placebo in end-stage renal disease patients preparing to undergo AV access creation.

METHODS

A total of 52 adult hemodialysis patients preparing for arteriovenous fistula (AVF) creation were randomized to receive perioperative high-dose cholecalciferol versus placebo in this double-blind, randomized, placebo-controlled pilot study. The primary outcome was mean response to high-dose oral cholecalciferol versus placebo, and secondary outcome AV access maturation at 6 months. Logistic regression was used to assess the association between AV access maturation and baseline, posttreatment and overall change in vitamin D concentration.

RESULTS

A total of 45% of cholecalciferol-treated and 54% of placebo-treated patients were successfully using their AVF or arteriovenous graft (AVG) at 6 months (p=0.8). Baseline serum concentrations of 25(OH)D and 1,25(OH)2D did not differ between those who experienced AVF or AVG maturation and those who did not (p=0.22 and 0.59, respectively). Similarly, there was no relationship between AVF or AVG maturation and posttreatment serum 25(OH)D and 1,25(OH)2D concentration (p=0.24 and 0.51, respectively).

CONCLUSIONS

Perioperative high-dose vitamin D3 therapy does correct 25(OH)D level but does not appear to have an association with AV access maturation rates. Future research may include extended preoperative vitamin D3 therapy in a larger population or in certain subpopulations at high risk for AVF failure.

Differences in progression to ESRD between black and white patients receiving predialysis care in a universal health care system

BACKGROUND AND OBJECTIVES

Studies performed in the United States showed that blacks progress from CKD to ESRD faster than do whites. Possible explanations are differences in health care system factors. This study investigated whether progression is also faster in a universal health care system, where all patients receive comparable care.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from the PREdialysis PAtient REcord study, a multicenter follow-up study of patients with CKD who started predialysis care in The Netherlands (1999-2011), were analyzed. Time-dependent Cox proportional hazards models were used to estimate the hazard ratio (HR) for starting renal replacement therapy (RRT), and linear mixed models were used to compare renal function decline (RFD) between blacks and whites. To explore possible mechanisms, analyses were adjusted for patient characteristics.

RESULTS

At initiation of predialysis care, blacks (n=49) were younger and had more diabetes mellitus, higher proteinuria levels, and a higher estimated GFR than whites (n=946). Median follow-up time in months was similar (blacks: 13.9 [boundaries of interquartile range (IQR), 5.3 to 19.5]; whites: 13.1 [IQR, 5.1 to 24.0]). For blacks compared with whites, the crude HR for starting RRT within the first 15 months was 0.86 (95% confidence interval [CI], 0.55 to 1.34) and from 15 months onward, 1.93 (95% CI, 1.02 to 3.68), which increased after adjustment. RFD was faster by 0.18 (95% CI, 0.05 to 0.32) ml/min per 1.73 m(2) per month in blacks compared with whites.

CONCLUSION

Blacks receiving predialysis care in a universal health care system have faster disease progression than whites, suggesting that health care system factors have a less influential role than had been thought in explaining black-white differences.

The effect of vitamin D status on risk factors for cardiovascular disease

Vitamin-D-related pathways are implicated in various endocrine, inflammatory and endothelial functions. An estimated 1 billion people in the world have vitamin D deficiency or insufficiency, and undiagnosed vitamin D deficiency is common. Vitamin D deficiency is associated with substantial increases in the incidence of hypertension, hyperlipidaemia, myocardial infarction and stroke, as well as in diseases such as chronic kidney disease and type 2 diabetes. Low vitamin D levels also upregulate the renin-angiotensin-aldosterone system, increase inflammation and cause endothelial dysfunction. However, the role of vitamin D deficiency in cardiovascular morbidity and mortality is an emerging and hotly debated topic. Epidemiological studies suggest an association between low vitamin D levels and risk factors for cardiovascular disease, but a causal relationship has not been established, and clinical trials and meta-analyses have not demonstrated convincing evidence that vitamin D therapy improves cardiovascular outcomes. Some evidence suggests that vitamin D status is a biomarker of lifestyle, since unhealthy and sedentary lifestyles are associated with vitamin D insufficiency or deficiency and are also risk factors for cardiovascular complications.

25-Hydroxyvitamin D concentrations and risk of venous thromboembolism in the general population with 18,791 participants

BACKGROUND

Vitamin D has potential antithrombotic effects, suggesting that vitamin D analogs could be used as adjunctive antithrombotic agents. However, epidemiologic evidence of an association between reduced 25-hydroxyvitamin D concentrations and the risk of venous thromboembolism is lacking.

OBJECTIVES

To test the hypothesis that reduced plasma 25-hydroxyvitamin D concentrations are associated with an increased risk of venous thromboembolism in the general population.

METHODS

We prospectively studied 18 791 participants from the Copenhagen City Heart Study and the Copenhagen General Population Study. During up to 30 years of follow-up, 950 participants were diagnosed with venous thromboembolism. Plasma 25-hydroxyvitamin D concentrations were adjusted for seasonal variation.

RESULTS

The cumulative incidence of venous thromboembolism as a function of age increased with decreasing tertiles of seasonally adjusted plasma 25-hydroxyvitamin D (log-rank trend: P = 4 × 10(-4) ). On comparison of participants in the lowest and the highest tertile of plasma 25-hydroxyvitamin D concentrations, the crude risk estimate in a model adjusted for age and sex was a 37% (95% confidence interval [CI] 15-64%) increased risk of venous thromboembolism. The corresponding risk increase in a model adjusted for age, sex, body mass index, smoking and cancer was 26% (95% CI 5-51%), and in a multivariable-adjusted model also including physical activity, hormone replacement therapy, menopausal status, oral contraception use and lipid-lowering therapy it was 28% (95% CI 6-53%). Furthermore, corresponding risk increases with attempts to correct for regression dilution bias were 103% (95% CI 37-202%), 70% (95% CI 14-155%) and 73% (95% CI 15-160%) in the three models, respectively.

CONCLUSION

In these large general population studies, we observed a stepwise increasing risk of venous thromboembolism with decreasing tertiles of seasonally adjusted plasma 25-hydroxyvitamin D concentrations.

A prospective study of serum 25-hydroxyvitamin d levels and mortality among African Americans and non-African Americans

The beneficial biologic effects attributed to vitamin D suggest a potential to influence overall mortality. Evidence addressing this hypothesis is limited, especially for African Americans who have a high prevalence of vitamin D insufficiency. The authors conducted a nested case-control study within the prospective Southern Community Cohort Study to relate baseline serum levels of 25-hydroxyvitamin D (25(OH)D) with subsequent mortality. Cases were 1,852 participants who enrolled from 2002 to 2009 and died >12 months postenrollment. Controls (n = 1,852) were matched on race, sex, age, enrollment site, and blood collection date. The odds ratios for quartile 1 (<10.18 ng/mL) versus quartile 4 (>21.64 ng/mL) levels of 25(OH)D were 1.60 (95% confidence interval (CI): 1.20, 2.14) for African Americans and 2.11 (95% CI: 1.39, 3.21) for non-African Americans. The effects were strongest for circulatory disease death, where quartile 1 versus quartile 4 odds ratios were 2.53 (95% CI: 1.44, 4.46) and 3.25 (95% CI: 1.33, 7.93) for African Americans and non-African Americans, respectively. The estimated odds of total mortality were minimized in the 25(OH)D range of 35-40 ng/mL. These findings provide support for the hypothesis that vitamin D status may have an important influence on mortality for both African Americans and non-African Americans.

25-hydroxyvitamin D and symptomatic ischemic stroke: an original study and meta-analysis

OBJECTIVE

We tested the hypothesis that low plasma concentrations of 25-hydroxyvitamin D are associated with increased risk of symptomatic ischemic stroke in the general population.

METHODS

We measured plasma 25-hydroxyvitamin D in 10,170 individuals from the general population, the Copenhagen City Heart Study. During 21 years of follow-up, 1,256 and 164 persons developed ischemic and hemorrhagic stroke, respectively. In a meta-analysis of ischemic stroke, we included 10 studies, 58,384 participants, and 2,644 events.

RESULTS

Stepwise decreasing plasma 25-hydroxyvitamin D concentrations were associated with stepwise increasing risk of ischemic stroke both as a function of seasonally adjusted percentile categories and as a function of clinical categories of 25-hydroxyvitamin D (p for trend ≤ 2 × 10(-3)). In a Cox regression model comparing individuals with plasma 25-hydroxyvitamin D concentrations between the 1st and 4th percentiles to individuals with 25-hydroxyvitamin D concentrations between the 50th and 100th percentiles, multivariate adjusted hazard ratio of ischemic stroke was 1.82 (95% confidence interval, 1.41-2.34). Comparing individuals with clinical categories of severe vitamin D deficiency (<25.0 nmol/l [<10.0 ng/ml]) to individuals with optimal vitamin D status (≥75.0 nmol/l [≥30.0 ng/ml]), the multivariate adjusted hazard ratio of ischemic stroke was 1.36 (1.09-1.70). 25-Hydroxyvitamin D concentrations were not associated with risk of hemorrhagic stroke. In a meta-analysis comparing lowest versus highest quartile of 25-hydroxyvitamin D concentrations, the multivariate adjusted odds ratio of ischemic stroke was 1.54 (1.43-1.65) with a corresponding hazard ratio of 1.46 (1.35-1.58) in prospective general population studies.

INTERPRETATION

In this large population-based prospective study, we observed stepwise increasing risk of symptomatic ischemic stroke with decreasing plasma 25-hydroxyvitamin D concentrations. This finding was substantiated in a meta-analysis.

[Vitamin D hormone system and diabetes mellitus: lessons from selective activators of vitamin D receptor and diabetes mellitus]

The vitamin D hormone system has significant skeletal and extra-skeletal effects. Vitamin D receptor occurs in different tissues, and several cells other than renal cells are able to locally produce active vitamin D, which is responsible for transcriptional control of hundreds of genes related to its pleiotropic effects. There is increasing evidence relating vitamin D to development and course of type 1 and 2 diabetes mellitus. Specifically, influence of vitamin D on the renin-angiotensin-aldosterone system, inflammatory response, and urinary albumin excretion could explain the relevant impact of vitamin D status on diabetic nephropathy. Selective vitamin D receptor activators are molecules able to reproduce agonistic or antagonistic effects of active vitamin D depending on the tissue or even on the cell type. Specifically, paricalcitol has a beneficial profile because of its potency to reduce parathyroid hormone, with lower effects on serum calcium or phosphate levels. Moreover, in patients with diabetes and renal disease, paricalcitol decreases microalbuminuria, hospitalization rates, and cardiovascular mortality. Therefore, these molecules represent an attractive new option to improve prognosis of renal disease in patients with diabetes.

Shining D' light on chronic kidney disease: mechanisms that may underpin the cardiovascular benefit of vitamin D

Hypovitaminosis D is a significant health-care burden worldwide, particularly in susceptible populations such as those with chronic kidney disease (CKD). Recent epidemiological studies have identified that both higher serum vitamin D concentrations and use of vitamin D supplements may confer a survival benefit both in terms of all-cause and cardiovascular mortality. There is potential to investigate this inexpensive therapy for the CKD population, which suffers excessive cardiovascular events, although the mechanisms explaining this link have yet to be fully elucidated. This review discusses potential mechanisms identified in the basic science literature that may provide important insights into how vitamin D may orchestrate a change in cardiovascular risk profile through such diverse mechanisms as inflammation, atherogenesis, glucose homeostasis, vascular calcification, renin-angiotensin regulation and alterations in cardiac physiology. Where available, the clinical translation of these concepts to intervention trials in the CKD population will be reviewed.