Vitamin D Deficiency and the Risk of Cerebrovascular Disease

Genetic variants in FCGR2A, PTPN2, VDR as predictive signatures of aggressive phenotypes in cerebral cavernous malformation

OBJECTIVE

The biological behavior of Cerebral Cavernous Malformation (CCM) is still controversial, lacking a clear-cut signature for a mechanistic explanation of lesion aggressiveness. In this study, we evaluated the predictive capacity of genetic variants concerning the aggressive behavior of CCM and their implications in biological processes.

METHODS

We genotyped the variants in VDRrs7975232, VDRrs731236, VDRrs11568820, PTPN2rs72872125 and FCGR2Ars1801274 genes using TaqMan Genotyping Assays in a cohort study with 103 patients, 42 of whom had close follow-up visits for 4 years, focusing on 2 main aspects of the disease: (1) symptomatic events, which included both intracranial bleeding or epilepsy, and (2) the onset of symptoms. The genotypes were correlated with the levels of several cytokines quantified in peripheral blood, measured using the x-MAP method.

RESULTS

We report a novel observation that the PTPN2rs72872125 CT and the VDRrs7975232 CC genotype were independently associated with an asymptomatic phenotype. Additionally, PTPN2rs72872125 CC genotype and serum level of GM-CSF could predict a diagnostic association with symptomatic phenotype in CCM patients, while the FCGR2Ars1801274 GG genotype could predict a symptomatic event during follow-up. The study also found a correlation between VDRrs731236 AA and VDRrs11568820 CC genotype to the time to the first symptomatic event.

CONCLUSIONS

These genetic markers could pave the way for precision medicine strategies for CCM, enhancing patient outcomes by enabling customized therapeutic approaches.

Vitamin D deficiency in Mongolian men aged 15-49 years

We aimed to estimate the prevalence of vitamin D deficiency in Mongolian men aged from 15 to 49 years at the National level as part of the Fifth National Nutrition Survey in 2016. This was a cross-sectional survey, conducted between September and November in 21 aimags of 4 economic regions of the country, and also in Ulaanbaatar. Given the regional differences in lifestyle and nutritional status, the target populations were stratified into 5 strata based on their economic region and in Ulaanbaatar, with equal samples drawn from each stratum using a cluster-randomized sampling design. A representative sample of 30 clusters [villages] was randomly selected using Probability Proportional to Size [PPS] methodology in each of the 4 regions and in Ulaanbaatar for a total of 150 cluster units. The selection of survey participants differed for the three sampling regions. Household eligibility was based on having a child 0-59 months of age, living in the household which was randomly selected from each cluster for a total of 450 households in each region. Households with a child 0-59 months of age were selected from household lists available at the kheseg or bagh level. All men 15-49 years of age who resided in the selected households were also eligible to participate in the survey. Serum concentration of 25-hydroxyvitamin D [25(OH)D] were measured using an enzyme-linked fluorescence assay in 377 men aged 15-49 years. The overall mean serum level of 25(OH)D concentration was 22.26 ± 0.48 ng/mL (95 % CI 21.31-23.21). The mean serum 25(OH)D concentrations were 19.65 ± 0.32 ng/mL (95 % CI19.01-19.82), and 33.68 ± 0.49 ng/mL (95 % CI 32.72-34.64) in vitamin D deficient, and in vitamin D sufficient subjects, respectively. The prevalence of vitamin D deficiency was 83.5 % with no significant difference in the prevalence of vitamin D deficiency by age group, economic region, area, location, education, and wealth index quintile. The prevalence of men in this study who were overweight or obese was 48.8 % and 14.6 % respectively. Although no significant difference was found between vitamin D deficiency and obesity, vitamin D deficiency was higher among men aged 30-39 and 40-49 years old by age specific analyses. The men did not take vitamin D supplements, and there is currently no vitamin D food fortification in Mongolia. The findings of this survey showed that vitamin D deficiency in men is a public health problem in Mongolia. In conclusion, vitamin D deficiency are common in Mongolian men, which indicates the need for vitamin D screening and treatment, as well as for an increased use of vitamin D supplements and for implementing vitamin D food fortification programs.

Acute calcitriol treatment mitigates vitamin D deficiency-associated mortality after intracerebral haemorrhage

OBJECTIVE

Vitamin D deficiency (VDD) is emerging as a predictor of poor prognosis in various neurological conditions, where clinical outcomes are often worse in stroke patients with VDD. This study aimed to provide experimental evidence on whether and how pre-existing VDD would affect survival and neurofunctional outcomes in intracerebral haemorrhage (ICH), and to evaluate whether acute vitamin D (VD) supplementation would improve post-stroke outcomes.

METHODS

Experimental ICH models were induced in mice with and without VDD. Haematoma size was measured using T2*-weighted MRI and haemoglobin concentration. Post-ICH mortality, neurofunctional outcomes and the extent of blood-brain barrier (BBB) leakage were assessed to identify their correlations with VD status. Therapeutic benefits of acute VD administration were also evaluated.

RESULTS

Mice with VDD exhibited significantly higher acute mortality rates and more severe motor deficits than mice without VDD post-ICH. Marked haematoma expansion and increased Evans blue extravasation were observed in VDD mice, suggesting that VDD was associated outcomes with increased BBB disruption. Acute treatment with a loading dose of VD (calcitriol) significantly improved outcomes in VDD mice.

CONCLUSION

This study provides novel insights into the pathophysiological mechanisms at play in ICH concomitant with VDD and a scientific rationale for acute treatment with VD.

Vitamin D ameliorates celecoxib cardiotoxicity in a doxorubicin heart failure rat model via enhancement of the antioxidant defense and minimizing mitochondrial dysfunction

Recent evidence suggests the mechanistic role of mitochondria and oxidative stress in the development of celecoxib-induced cardiotoxicity. On the other, it has reported the positive effects of vitamin D on oxidative stress and the maintenance of mitochondrial functions. This current study examined the cardiac effects of celecoxib, doxorubicin, vitamin D, and a combination of them in rats. The effect of 10 days of celecoxib (100 mg/kg/day), doxorubicin (2.5 mg/kg), vitamin D (60,000 U/kg), and their combination was studied on cardiac function according to serum lactate dehydrogenase (LDH), creatine kinase (CK), glutathione (GSH), and malondialdehyde (MDA) levels as well as mitochondrial succinate dehydrogenases (SDH) activity, reactive oxygen species (ROS) production, mitochondrial swelling, and mitochondrial membrane potential (MMP). Results showed that celecoxib and its combination with doxorubicin led to abnormality in paws and limbs, increased pressure in the eyes, blindness and animal death (in about 75% of the animals under study). Moreover, celecoxib and its combination with doxorubicin significantly increased cardiotoxicity biomarkers, oxidative stress markers (GSH and MDA), and mitochondrial toxicity parameters (SDH, ROS formation, MMP collapse, mitochondrial swelling). However, the combination of vitamin D with celecoxib and celecoxib + doxorubicin caused a significant reversal of deformity in paws and limbs, increased pressure in the eye, blindness, and animal death, as well as cardiotoxicity, oxidative stress, and mitochondrial parameters. This study proved for the first time the beneficial effect of vitamin D on celecoxib-induced cardiotoxicity, which is aggravated in the presence of doxorubicin through the maintenance of mitochondrial functions and its antioxidant potential.

Vitamin D deficiency in patients with retinal vein occlusion: a systematic review and meta-analysis

BACKGROUND

This review aims to substantiate the correlation between vitamin D and retinal vein occlusion (RVO) within the medical literature.

METHOD

A systematic review and meta-analysis were conducted in PubMed, SCOPUS, Web of Science, and Embase until December 10th, 2023. A meticulous literature search was undertaken to identify and analyze all observational-analytical papers reporting vitamin D levels in RVO patients. The principal outcome measures centered on the comparative assessment of vitamin D levels between patients with RVO (cases) and those devoid of RVO (controls). The protocol was registered in PROSPERO (code: CRD42024499853).

RESULTS

A total of six relevant studies consisting of 589 participants were included in this meta-analysis. The results indicated a significant association between vitamin D deficiency and increased risk of RVO (Odds ratio = 14.51; 95% CI: [1.71, 122.59], P = 0.014); and patients with RVO exhibited a significant decrease in serum vitamin D levels by 1.91ng/mL (95% CI: [-2.29, -1.54], P < 0.001). Moreover, there was no significant difference observed in vitamin D levels between central RVO (CRVO) and branch RVO (BRVO) subtypes (P = 0.63).

CONCLUSION

RVO patients have more vitamin D deficiency than healthy controls. These results contribute to the growing body of evidence highlighting the intricate role of vitamin D supplementation as both a prophylactic and a treatment strategy in RVO.

PROSPERO REGISTRATION IDENTIFIER

CRD42024499853.

Selected serum cytokines and vitamin D levels as potential prognostic markers of acute ischemic stroke

Inflammation-derived oxidative stress is postulated to contribute to neuronal damage leading to poor clinical outcomes in Acute Ischemic Stroke (AIS). We aimed to investigate the association between serum levels of selected cytokines (IL-1β, IFN-γ, IL-4), and vitamin D in ischemic stroke progression, and their accuracy in predicting AIS prognosis, among Sri Lankans. We compared 60 AIS patients admitted in 4 phases post-stroke onset (<6 h; 6-24 h; 24-48 h; 48-96 h; n = 15/phase), with 15 age- and sex-matched controls. The 30-day functional outcome (FO) was assessed using the modified Rankin Scale (mRS). Serum cytokine and vitamin D levels were quantified using sandwich ELISAs, and competitive ELISA, respectively. The CombiROC web tool established optimal prognostic biomarker combinations. Serum IL-1β and IFN-γ were elevated in all four phases following stroke onset while IL-4 was elevated exclusively in the recovery phase (48-96 h) (p<0.05). Th1 bias polarization of the Th1:Th2 cytokine (IFN-γ:IL-4) ratio occurred with AIS progression while a Th2 bias occurred during AIS recovery (p<0.05). Lower serum IL-1β and higher IL-4 levels were associated with a good FO (p<0.05), while lower Vitamin D levels were related to a poor FO (p = 0.001). The triple-biomarker panel, IL-4- IFN-γ -Vit D, accurately predicted AIS prognosis (sensitivity = 100%, specificity = 91.9%, area under the curve = 0.98). Serum immunologic mediators IFN-γ, IL-4, and vitamin D may be useful biomarkers of AIS prognosis and may serve as therapeutic targets in improving stroke outcomes. Vitamin D supplementation may improve the prognosis of AIS patients. Furthermore, binary logistic model fitted for FO indicated Th1:Th2 cytokine ratio (IFN-γ:IL-4), vitamin D status, history of stroke, and ischemic heart disease as significant predictors of AIS prognosis.

Association of 25-hydroxyvitamin D, lipoprotein-associated phospholipase A2 and asymptomatic coronary artery disease in patients with type 2 diabetes mellitus

AIM

To evaluate the relationship of 25-hydroxyvitamin D (25(OH)D), lipoprotein-associated phospholipase A2 (Lp-PLA2), and coronary artery disease (CAD) in type 2 diabetes mellitus (T2DM) patients with no history or symptoms of cardiovascular disease.

METHODS

The study identified 66 pairs of T2DM patients with and without CAD using propensity score matching. All subjects performed coronary computed tomography angiography (CCTA). Data on 25(OH)D, Lp-PLA2, and metabolic indexes were collected and analyzed.

RESULTS

Compared to the patients without CAD, the patients with CAD had lower 25(OH)D levels and the rate of vitamin D sufficiency, but higher Lp-PLA2 levels. Meanwhile, subjects in the vitamin D sufficiency group had a lower prevalence of CAD and Lp-PLA2 levels. Furthermore, 25(OH)D was inversely correlated with Lp-PLA2, Gensini score, Leiden score, segment involvement score, and segment stenosis score (P < 0.05). After adjusting for age, gender, blood lipids and blood pressure, 25(OH)D was associated with a decreased risk of CAD (aOR 0.933, 95 %CI 0.887-0.983, P = 0.009), while Lp-PLA2 was associated with an increased risk of CAD (aOR 1.014, 95 %CI 1.005-1.022, P = 0.002).

CONCLUSIONS

Decreased 25(OH)D and increased Lp-PLA2 could identify patients with a high risk of CAD and are associated with the severity of coronary artery stenosis in T2DM.

Persistence of vitamin D deficiency among Italian patients with acute myocardial infarction

BACKGROUND AND AIMS

Vitamin D deficiency is a common cardiovascular risk factor associated with the development of atherosclerosis. We evaluated changes in 25(OH)D concentrations in 1510 patients with acute myocardial infarction (AMI) over a long observation period, including the COVID-19 pandemic.

METHODS AND RESULTS

Patients were separated into four groups according to the year of enrolment, group 1 (2009-2010), group 2 (2014-2016), group 3 (2017-2019), and group 4 (2020-2022). The median 25(OH)D concentration in the overall cohort was 17.15 (10.3-24.7) ng/mL. The median plasma concentrations of 25(OH)D for groups 1, 2, 3, and 4 were 14.45 (7.73-22.58) ng/mL, 17.3 ng/mL (10.33-24.2), 18.95 (11.6-26.73) ng/mL and 19.05 (12.5-27.3) ng/mL, respectively. Although 25(OH)D levels increased over the years, the prevalence of vitamin D deficiency remained high in each group (68.4%, 61.4%, 53.8%, and 52% respectively). Hypovitaminosis D was predicted by the season influence (OR:2.03, p < 0.0001), higher body mass index (OR:1.25; p = 0.001), diabetes mellitus (OR:1.54; p = 0.001), smoking (OR:1.47; p = 0.001), older age (OR:1.07; p = 0.008), higher triglycerides levels (OR:1.02; p = 0.01), and female gender (OR:1.3; p = 0.038). After multivariable adjustment, vitamin D ≤ 20 ng/mL was an independent predictor of mortality.

CONCLUSION

Vitamin D deficiency is highly prevalent and persistent in patients with AMI despite a trend towards increasing 25(OH)D concentrations over the years. The frequent lockdowns did not reduce the levels of 25(OH)D in the fourth group. Low levels of 25(OH)D are an independent predictor of mortality.

The identification of small molecule inhibitors with anthelmintic activities that target conserved proteins among ruminant gastrointestinal nematodes

Gastrointestinal nematode (GIN) infections are a major concern for the ruminant industry worldwide and result in significant production losses. Naturally occurring polyparasitism and increasing drug resistance that potentiate disease outcomes are observed among the most prevalent GINs of veterinary importance. Within the five major taxonomic clades, clade Va represents a group of GINs that predominantly affect the abomasum or small intestine of ruminants. However, the development of effective broad-spectrum anthelmintics against ruminant clade Va GINs has been challenged by a lack of comprehensive druggable genome resources. Here, we first assembled draft genomes for three clade Va species (Cooperia oncophora, Trichostrongylus colubriformis, and Ostertagia ostertagi) and compared them with closely related ruminant GINs. Genome-wide phylogenetic reconstruction showed a relationship among ruminant GINs structured by taxonomic classification. Orthogroup (OG) inference and functional enrichment analyses identified 220 clade Va-specific and Va-conserved OGs, enriched for functions related to cell cycle and cellular senescence. Further transcriptomic analysis identified 61 taxonomically and functionally conserved clade Va OGs that may function as drug targets for new broad-spectrum anthelmintics. Chemogenomic screening identified 11 compounds targeting homologs of these OGs, thus having potential anthelmintic activity. In in vitro phenotypic assays, three kinase inhibitors (digitoxigenin, K-252a, and staurosporine) exhibited broad-spectrum anthelmintic activities against clade Va GINs by obstructing the motility of exsheathed L3 (xL3) or molting of xL3 to L4. These results demonstrate valuable applications of the new ruminant GIN genomes in gaining better insights into their life cycles and offer a contemporary approach to discovering the next generation of anthelmintics.IMPORTANCEGastrointestinal nematode (GIN) infections in ruminants are caused by parasites that inhibit normal function in the digestive tract of cattle, sheep, and goats, thereby causing morbidity and mortality. Coinfection and increasing drug resistance to current therapeutic agents will continue to worsen disease outcomes and impose significant production losses on domestic livestock producers worldwide. In combination with ongoing therapeutic efforts, advancing the discovery of new drugs with novel modes of action is critical for better controlling GIN infections. The significance of this study is in assembling and characterizing new GIN genomes of Cooperia oncophora, Ostertagia ostertagi, and Trichostrongylus colubriformis for facilitating a multi-omics approach to identify novel, biologically conserved drug targets for five major GINs of veterinary importance. With this information, we were then able to demonstrate the potential of commercially available compounds as new anthelmintics.

Blood-based biomarkers of cerebral small vessel disease

Age-associated cerebral small vessel disease (CSVD) represents a clinically heterogenous condition, arising from diverse microvascular mechanisms. These lead to chronic cerebrovascular dysfunction and carry a substantial risk of subsequent stroke and vascular cognitive impairment in aging populations. Owing to advances in neuroimaging, in vivo visualization of cerebral vasculature abnormities and detection of CSVD, including lacunes, microinfarcts, microbleeds and white matter lesions, is now possible, but remains a resource-, skills- and time-intensive approach. As a result, there has been a recent proliferation of blood-based biomarker studies for CSVD aimed at developing accessible screening tools for early detection and risk stratification. However, a good understanding of the pathophysiological processes underpinning CSVD is needed to identify and assess clinically useful biomarkers. Here, we provide an overview of processes associated with CSVD pathogenesis, including endothelial injury and dysfunction, neuroinflammation, oxidative stress, perivascular neuronal damage as well as cardiovascular dysfunction. Then, we review clinical studies of the key biomolecules involved in the aforementioned processes. Lastly, we outline future trends and directions for CSVD biomarker discovery and clinical validation.

Endogenous and exogenous protection from surgically induced reactive oxygen and nitrogen species

Surgical intervention creates reactive oxygen species through diverse molecular mechanisms, including direct stimulation of immune-mediated inflammation necessary for wound healing. However, dysregulation of redox homeostasis in surgical patients overwhelms the endogenous defense system, slowing the healing process and damaging organs. We broadly surveyed reactive oxygen species that result from surgical interventions and the endogenous and/or exogenous antioxidants that control them. This study assimilates current reports on surgical sources of reactive oxygen and nitrogen species along with literature reports on the effects of endogenous and exogenous antioxidants in human, animal, and clinical settings. Although exogenous antioxidants are generally beneficial, endogenous antioxidant systems account for over 80% of total activity, varying based on patient age, sex, and health or co-morbidity status, especially in smokers, the diabetic, and the obese. Supplementation of exogenous compounds for support in surgical patients is thus theoretically beneficial, but a lack of persuasive clinical evidence has left this potential patient support strategy without clear guidelines. A more thorough understanding of the mechanisms of exogenous antioxidants in patients with compromised health statuses and pharmacokinetic profiling may increase the utility of such support in both the operating and recovery rooms.

Effects of Gender and Vitamin D on Vascular Reactivity of the Carotid Artery on a Testosterone-Induced PCOS Model

The negative cardiovascular effects of polycystic ovary syndrome (PCOS) and vitamin D deficiency (VDD) have been discussed previously; however, the sex differences between PCOS females and males are not yet known. Our aim was to investigate the effect of PCOS and VDD in the carotid artery of male and female Wistar rats. Females were treated with transdermal testosterone (Androgel) for 8 weeks, which caused PCOS. VDD and vitamin D supplementation were accomplished via diet. The carotid arteries' contraction and relaxation were examined using myography. Receptor density was investigated using immunohistochemistry. In PCOS females, angiotensin receptor density, angiotensin II-induced contraction, androgen receptor optical density, and testosterone-induced relaxation increased. The increased contractile response may increase cardiovascular vulnerability in women with PCOS. As an effect of VDD, estrogen receptor density increased in all our groups, which probably compensated for the reduced relaxation caused by VDD. Testosterone-induced relaxation was decreased as a result of VDD in males and non-PCOS females, whereas this reduction was absent in PCOS females. Male sex is associated with increased contraction ability compared with non-PCOS and PCOS females. VDD and Androgel treatment show significant gender differences in their effects on carotid artery reactivity. Both VDD and PCOS result in a dysfunctional vascular response, which can contribute to cardiovascular diseases.

Attenuation of morphine conditioned place preference and reinstatement by vitamin D

Opioid action in the brain involves the dopamine-reward system as well as non-dopamine pathways. Since vitamin D also modulates the brain's dopamine system, the question of this study was how vitamin D might affect the opioid influences on the reward system. Therefore, the objective of this study was to investigate the possible effect of vitamin D on the conditioned place preference (CPP) induced by morphine, as a valuable model of assessment of the reinforcing properties of opioids by associating the context to the rewarding properties of the addictive drugs. Male Wistar rats were randomly divided into two main groups that either received saline (morphine vehicle) or morphine (5 mg/kg, intraperitoneally) for CPP. Each of the main groups was divided into three vitamin D treatment subgroups: vitamin D vehicle and vitamin D (5 and 10 μg/kg, intraperitoneally). Vitamin D injections were started 1 week ahead of the experiment (two injections) or immediately after post-conditioning and in both cases, it was continued twice weekly throughout the CPP. Administration of vitamin D (10 μg/kg) before conditioning in CPP markedly attenuated morphine expression in the post-conditioning test. Receiving vitamin D (5 or 10 μg/kg) before or after conditioning significantly attenuated morphine reinstatement. Administration of vitamin D after opioid conditioning facilitated morphine memory extinction and attenuated morphine reinstatement. Vitamin D is probably a valuable addition to be considered as a part of the treatment for prevention or minimizing the dependency or relapse to opioids.

Lower 25-hydroxyvitamin D is associated with severer white matter hyperintensity and cognitive function in patients with non-disabling ischemic cerebrovascular events

OBJECTIVES

This study aimed to investigate the potential correlations among serum 25-hydroxyvitamin D [25(OH)D] levels, white matter hyperintensity (WMH) and cognitive function in patients with non-disabling ischemic cerebrovascular events (NICE).

METHODS

This was a prospective investigation of 160 NICE patients with age of 40 years or older. Cognitive function was evaluated by the Montreal Cognitive Assessment (MoCA). White matter lesions were evaluated by WMH using Fazekas scores. Spearman correlation analysis and linear regression models were used to identify the associations between serum 25(OH)D levels and cognitive function. Binary logistic regression analysis models were used to evaluate the predictable value of serum 25(OH)D levels and WMH for cognitive impairment.

RESULTS

Patients with inadequate 25(OH)D levels had lower MoCA score (P=0.008), and a higher proportion of severe WMH (P=0.043). Spearman correlation analysis demonstrated that serum 25(OH)D concentrations were positively associated with MoCA score (rs=0.185, P=0.019) while negatively related to the proportion of severe WMH (sWMH) (rs=-0.166, P=0.036).The association between 25(OH)D concentrations and MoCA score remained significant in linear regression (adjusted β=0.012, 95%CI:0.001-0.203).Adjusted binary logistic regression analysis showed that the odds ratio of cognitive impairment with insufficient 25(OH)D concentration was 5.038 (95%CI:1.154-21.988) compared with the sufficient group and the sWMH (OR=2.728, 95%CI:1.230-6.051) was identified as an independent risk factor for cognitive decline in NICE patients.

CONCLUSION

Serum 25(OH)D levels and white matter lesions were independently and significantly associated with cognitive impairment in NICE patients.

Disruption of Vitamin D Signaling Impairs Adaptation of Cerebrocortical Microcirculation to Carotid Artery Occlusion in Hyperandrogenic Female Mice

Vitamin D deficiency contributes to the pathogenesis of age-related cerebrovascular diseases, including ischemic stroke. Sex hormonal status may also influence the prevalence of these disorders, indicated by a heightened vulnerability among postmenopausal and hyperandrogenic women. To investigate the potential interaction between sex steroids and disrupted vitamin D signaling in the cerebral microcirculation, we examined the cerebrovascular adaptation to unilateral carotid artery occlusion (CAO) in intact, ovariectomized, and hyperandrogenic female mice with normal or functionally inactive vitamin D receptor (VDR). We also analyzed the morphology of leptomeningeal anastomoses, which play a significant role in the compensation. Ablation of VDR by itself did not impact the cerebrocortical adaptation to CAO despite the reduced number of pial collaterals. While ovariectomy did not undermine compensatory mechanisms following CAO, androgen excess combined with VDR inactivity resulted in prolonged hypoperfusion in the cerebral cortex ipsilateral to the occlusion. These findings suggest that the cerebrovascular consequences of disrupted VDR signaling are less pronounced in females, providing a level of protection even after ovariectomy. Conversely, even short-term androgen excess with lacking VDR signaling may lead to unfavorable outcomes of ischemic stroke, highlighting the complex interplay between sex steroids and vitamin D in terms of cerebrovascular diseases.

Serum Vitamin D Level as a Risk Factor and Prognostic Marker for Acute Ischemic Stroke: A Case-Control Study at a Tertiary Care Centre in Northern India

Introduction Stroke is a predominant cause of death worldwide. Major risk factors for stroke in any age group are diabetes, hypertension, heart disease, smoking, and long-term alcohol abuse. It is of utmost importance to identify the risk factors for stroke to prevent recurrence. Vitamin D deficiency is identified as a risk factor for stroke. Therefore, we attempted to look for a correlation between vitamin D levels and acute ischemic stroke. Methods This observational case-control study was conducted with 150 patients (75 cases and 75 controls). On the day of admission, the National Institutes of Health Stroke Scale (NIHSS) score was calculated, and vitamin D levels were measured for each patient. The functional outcome was determined by the modified Rankin scale (mRS). Results The most common risk factors identified in this study were hypertension (61.3%), diabetes mellitus (41.3%), and smoking (37.3%). Out of 75 patients enrolled in the study, 49.4% had significant vitamin D deficiency, and 30.6% had insufficient vitamin D levels. Our study showed a significant correlation between vitamin D sufficiency in the body and the incidence of stroke (x2=3.888 and p=0.048). A significant correlation (p=0.03) was found between the NIHSS score and vitamin D levels in patients with acute ischemic stroke. Conclusion In this observational case-control study, we concluded that the increasing severity of vitamin D deficiency was associated with more deaths and poor outcomes.

Neuroimmunological Effect of Vitamin D on Neuropsychiatric Long COVID Syndrome: A Review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the coronavirus disease 2019 (COVID-19). COVID-19 is now recognized as a multiorgan disease with a broad spectrum of manifestations. A substantial proportion of individuals who have recovered from COVID-19 are experiencing persistent, prolonged, and often incapacitating sequelae, collectively referred to as long COVID. To date, definitive diagnostic criteria for long COVID diagnosis remain elusive. An emerging public health threat is neuropsychiatric long COVID, encompassing a broad range of manifestations, such as sleep disturbance, anxiety, depression, brain fog, and fatigue. Although the precise mechanisms underlying the neuropsychiatric complications of long COVID are presently not fully elucidated, neural cytolytic effects, neuroinflammation, cerebral microvascular compromise, breakdown of the blood-brain barrier (BBB), thrombosis, hypoxia, neurotransmitter dysregulation, and provoked neurodegeneration are pathophysiologically linked to long-term neuropsychiatric consequences, in addition to systemic hyperinflammation and maladaptation of the renin-angiotensin-aldosterone system. Vitamin D, a fat-soluble secosteroid, is a potent immunomodulatory hormone with potential beneficial effects on anti-inflammatory responses, neuroprotection, monoamine neurotransmission, BBB integrity, vasculometabolic functions, gut microbiota, and telomere stability in different phases of SARS-CoV-2 infection, acting through both genomic and nongenomic pathways. Here, we provide an up-to-date review of the potential mechanisms and pathophysiology of neuropsychiatric long COVID syndrome and the plausible neurological contributions of vitamin D in mitigating the effects of long COVID.

Roles of Oxidative Stress in Synaptic Dysfunction and Neuronal Cell Death in Alzheimer's Disease

Alzheimer's disease (AD) is a brain disorder that progressively undermines memory and thinking skills by affecting the hippocampus and entorhinal cortex. The main histopathological hallmarks of AD are the presence of abnormal protein aggregates (Aβ and tau), synaptic dysfunction, aberrant proteostasis, cytoskeletal abnormalities, altered energy homeostasis, DNA and RNA defects, inflammation, and neuronal cell death. However, oxidative stress or oxidative damage is also evident and commonly overlooked or considered a consequence of the advancement of dementia symptoms. The control or onset of oxidative stress is linked to the activity of the amyloid-β peptide, which may serve as both antioxidant and pro-oxidant molecules. Furthermore, oxidative stress is correlated with oxidative damage to proteins, nucleic acids, and lipids in vulnerable cell populations, which ultimately lead to neuronal death through different molecular mechanisms. By recognizing oxidative stress as an integral feature of AD, alternative therapeutic or preventive interventions are developed and tested as potential or complementary therapies for this devastating neurodegenerative disease.

SIRT1 and antioxidants in infertile females: Exploration of the role of vitamin D

BACKGROUND

Deficiency of silent information regulator 1 (SIRT1) can trigger inflammation, mitochondrial malfunctioning, and apoptosis through the hypothalamic-pituitary-ovarian axis, producing poor quality oocytes, leading to infertility. Normal vitamin D (VD) levels promote SIRT1 activity required for optimal fertility, and low levels of either may result in fertility problems owing to cell-membrane de-stabilization, increased autophagy, DNA damage leading to increased reactive oxygen species and mitochondrial dysfunction. Therefore, in this study, we want to estimate the levels of VD, SIRT1 and antioxidants (MnSOD; manganese superoxide dismutase, GR; glutathione reductase, visfatin) and oxidants (adrenaline & cortisol) in individuals living with infertility and explore the association of VD with SIRT1 expression (levels), antioxidants, and oxidants contributing to infertility in women. The significance of this study is that it highlights the importance of maintaining optimal levels of VD for reproductive health in females.

METHODS

This cross-sectional study included 342 (135 infertile and 207 fertile) female subjects. Serum levels of MnSOD, SIRT1, visfatin, GR, VD, adrenaline, and cortisol were analyzed by ELISA and were compared in fertile and infertile samples using the Mann Whitney U test.

RESULTS

There were significantly high levels of VD, SIRT1, GR, MnSOD and visfatin in fertile female participants. However, mean adrenaline and cortisol levels were higher in infertile samples with a significant negative correlation with VD. A significant negative correlation of VD with MnSOD, SIRT1, visfatin and GR was observed (p <0.01). In VD subset groups, MnSOD levels were significantly high in VD sufficient groups however, adrenaline and cortisol levels were significantly high in groups suffering from VD deficiency.

CONCLUSIONS

Deficiency of VD is associated with a decrease in SIRT1 and other antioxidants, which may deter natural reproductive functions leading to infertility. Further studies are required to determine the cause-effect relationship of VD deficiency on conception and interpretation of the involved mechanism.

The Role of Vitamin D in Reducing the Risk of Metabolic Disturbances That Cause Cardiovascular Diseases

Among the most common problems facing public health today is a lack of vitamin D, which plays a role in the physiological processes of chronic illness conditions. Vitamin D deficiency in metabolic disorders has primary effects on osteoporosis, obesity, hypertension, diabetes, and cardiovascular disease (CVD). Vitamin D acts as a "co-hormone" in the various tissues of the body, and it has been found that vitamin D receptors (VDR) are present on all cell types, suggesting that vitamin D has a wide range of effects on most cells. Recently, there has been a surge in interest in assessing its roles. Vitamin D insufficiency increases the risk of diabetes because it lowers insulin sensitivity, and also raises the risk of obesity and CVD because of its effect on the body's lipid profile, particularly in terms of the prevalence of dangerously high levels of low-density lipoproteins (LDL). Furthermore, vitamin D insufficiency is often related to CVD and connected risk factors, highlighting the need to know vitamin D's functions in relation to metabolic syndrome and related processes. Through looking at previous studies, this paper explains why vitamin D is important, how deficiency is related to risk factors for metabolic syndrome through different mechanisms, and how deficiency affects CVD.

Association between serum 25(OH)D and risk of all-cause mortality in adults with prior cardiovascular disease: a cohort study from NHANES 2007-2018

BACKGROUND

Serum vitamin D deficiency is common in the patients with cardiovascular disease (CVD), but the association between serum vitamin D levels and risk of all-cause mortality in patients with CVD is controversial.

OBJECTIVE

This study aimed to understand better the association between serum 25(OH)D status and risk of all-cause mortality in patients with prior CVD.

METHOD

We conducted a cohort study using data from the National Health and Nutrition Examination Survey from 2007 to 2018 to investigate the association between serum 25(OH)D and the risk of all-cause mortality using multivariate Cox regression models, with further subgroup analyses and interactions smooth curve fitting to address possible nonlinearities.

RESULT

A total of 3220 participants with prior CVD were included in this study, with a total of 930 deaths over a median follow-up of 5.52 years, with multivariable-adjusted serum vitamin D levels after natural log transformation (4.31-4.5 ) as a reference in COX regression, and corrected HRs and 95% CIs of 1.81 (1.31, 2.50), 1.34 (1.07, 1.66), 1.28 (1.05, 1.56),1.00 (reference), 1.10 (0.89, 1.37) for all-cause mortality, respectively. Results remained robust in the stratified analysis of interactions, but a L-shaped relationship was detected. We identified an inflection point of 4.5 after multivariate adjustment through a two-stage linear regression model and recursive algorithm.

CONCLUSION

Our findings demonstrate that increasing serum 25(OH)D levels may have a L-shaped relationship with risk of all-cause mortality and that increases in serum 25(OH)D levels do not continue to reduce the risk of all-cause mortality.

Antioxidants prevent particulate matter-induced senescence of lung fibroblasts

Particulate matter (PM) contributes to human diseases, particularly lung disease; however, the molecular mechanism of its action is yet to be determined. Herein, we found that prolonged PM exposure induced the cellular senescence of normal lung fibroblasts via a DNA damage-mediated response. This PM-induced senescence (PM-IS) was only observed in lung fibroblasts but not in A549 lung adenocarcinoma cells. Mechanistic analysis revealed that reactive oxygen species (ROS) activate the DNA damage response signaling axis, increasing p53 phosphorylation, ultimately leading to cellular senescence via an increase in p21 expression without affecting the p16-pRB pathway. A549 cells, instead, were resistant to PM-IS due to the PM-induced ROS production suppression. Water-soluble antioxidants, such as vitamin C and N-Acetyl Cysteine, were found to alleviate PM-IS by suppressing ROS production, implying that antioxidants are a promising therapeutic intervention for PM-mediated lung pathogenesis.

Association of Long Non-Coding RNA Malat1 with Serum Levels of Interleukin-1 Beta and Vitamin D in Patients with Ischemic Stroke

BACKGROUND

Previous studies have demonstrated the strong association of inflammatory cytokines and vitamin D (VitD) deficiency and ischemic stroke (IS) pathogenesis. Due to the negative correlation between long non-coding RNA (lncRNA) Malat1 and pro-inflammatory factors we decided to investigate the associations between Malat1 expression with serum interleukin-1β (IL-1β), and VitD levels in IS patients.

MATERIALS AND METHODS

In this cross-sectional study, 63 IS patients were included. We used enzyme-linked immunosorbent assays to evaluate the serum levels of VitD and IL-1β. Malat1 expression was evaluated by the real-time polymerase chain reaction test. The associations between Malat1expression with VitD and IL-1β were analysed with linear regression (Stepwise model) and Pearson's correlation analysis.

RESULTS

The Malat1 expression was inversely correlated with stroke severity (r=-0.25, P=0.043). Stepwise regression analysis showed a significant positive relationship between VitD level and Malat1 expression (Beta=0.28, P=0.02), and also showed a non-significant negative relationship between IL-1β and stroke severity. VitD level showed a positive Pearson correlation with Malat1 (r=0.28, P=0.023) and a negative correlation with IL-1β (r=-0.29, P=0.018) while it could not detect a significantly negative correlation with stroke severity.

CONCLUSION

For the first time the associations between Malat1 expression with IL-1β and VitD in IS patients was analyzed. We found a significant positive relationship between VitD and Malat1. This correlation needs to be investigated with a larger sample size to achieve a strong and reliable association between VitD and Malat1.

The Vitamin D Receptor as a Potential Target for the Treatment of Age-Related Neurodegenerative Diseases Such as Alzheimer's and Parkinson's Diseases: A Narrative Review

The vitamin D receptor (VDR) belongs to the nuclear receptor superfamily of transcription factors. The VDR is expressed in diverse brain regions and has been implicated in the neuroprotective, antiaging, prosurvival, and anti-inflammatory action of vitamin D. Accordingly, a relationship between vitamin D insufficiency and susceptibility to neurodegenerative diseases has been suggested. However, due to the multitargeted mechanisms of vitamin D and its often overlapping genomic and nongenomic effects, the role of the VDR in brain pathologies remains obscure. In this narrative review, we present progress in deciphering the molecular mechanism of nuclear VDR-mediated vitamin D effects on prosurvival and anti-inflammatory signaling pathway activity within the central nervous system. In line with the concept of the neurovascular unit in pathomechanisms of neurodegenerative diseases, a discussion of the role of the VDR in regulating the immune and vascular brain systems is also included. Next, we discuss the results of preclinical and clinical studies evaluating the significance of vitamin D status and the efficacy of vitamin D supplementation in the treatment of Parkinson's and Alzheimer's diseases, emphasizing the possible role of the VDR in these phenomena. Finally, the associations of some VDR polymorphisms with higher risks and severity of these neurodegenerative disorders are briefly summarized.

Dietary Supplements Potentially Target Plasma Glutathione Levels to Improve Cardiometabolic Health in Patients with Diabetes Mellitus: A Systematic Review of Randomized Clinical Trials

Cardiovascular diseases (CVDs) continue to be the leading cause of death in people with diabetes mellitus. Severely suppressed intracellular antioxidant defenses, including low plasma glutathione (GSH) levels, are consistently linked with the pathological features of diabetes such as oxidative stress and inflammation. In fact, it has already been established that low plasma GSH levels are associated with increased risk of CVD in people with diabetes. Dietary supplements are widely used and may offer therapeutic benefits for people with diabetes at an increased risk of developing CVDs. However, such information remains to be thoroughly scrutinized. Hence, the current systematic review explored prominent search engines, including PubMed and Google Scholar, for updated literature from randomized clinical trials reporting on the effects of dietary supplements on plasma GSH levels in people with diabetes. Available evidence indicates that dietary supplements, such as coenzyme Q10, selenium, curcumin, omega-3 fatty acids, and vitamin E or D, may potentially improve cardiometabolic health in patients with diabetes. Such beneficial effects are related to enhancing plasma GSH levels and reducing cholesterol, including biomarkers of oxidative stress and inflammation. However, available evidence is very limited and additional clinical studies are still required to validate these findings, including resolving issues related to the bioavailability of these bioactive compounds.

Multidrug-Loaded Lipid Nanoemulsions for the Combinatorial Treatment of Cerebral Cavernous Malformation Disease

Cerebral cavernous malformation (CCM) or cavernoma is a major vascular disease of genetic origin, whose main phenotypes occur in the central nervous system, and is currently devoid of pharmacological therapeutic strategies. Cavernomas can remain asymptomatic during a lifetime or manifest with a wide range of symptoms, including recurrent headaches, seizures, strokes, and intracerebral hemorrhages. Loss-of-function mutations in KRIT1/CCM1 are responsible for more than 50% of all familial cases, and have been clearly shown to affect cellular junctions, redox homeostasis, inflammatory responses, and angiogenesis. In this study, we investigated the therapeutic effects of multidrug-loaded lipid nanoemulsions in rescuing the pathological phenotype of CCM disease. The pro-autophagic rapamycin, antioxidant avenanthramide, and antiangiogenic bevacizumab were loaded into nanoemulsions, with the aim of reducing the major molecular dysfunctions associated with cavernomas. Through Western blot analysis of biomarkers in an in vitro CCM model, we demonstrated that drug-loaded lipid nanoemulsions rescue antioxidant responses, reactivate autophagy, and reduce the effect of pro-angiogenic factors better than the free drugs. Our results show the importance of developing a combinatorial preventive and therapeutic approach to reduce the risk of lesion formation and inhibit or completely revert the multiple hallmarks that characterize the pathogenesis and progression of cavernomas.

Genomic or Non-Genomic? A Question about the Pleiotropic Roles of Vitamin D in Inflammatory-Based Diseases

Vitamin D (vit D) is widely known for its role in calcium metabolism and its importance for the bone system. However, various studies have revealed a myriad of extra-skeletal functions, including cell differentiation and proliferation, antibacterial, antioxidant, immunomodulatory, and anti-inflammatory properties in various cells and tissues. Vit D mediates its function via regulation of gene expression by binding to its receptor (VDR) which is expressed in almost all cells within the body. This review summarizes the pleiotropic effects of vit D, emphasizing its anti-inflammatory effect on different organ systems. It also provides a comprehensive overview of the genetic and epigenetic effects of vit D and VDR on the expression of genes pertaining to immunity and anti-inflammation. We speculate that in the context of inflammation, vit D and its receptor VDR might fulfill their roles as gene regulators through not only direct gene regulation but also through epigenetic mechanisms.

Role of Vitamin D Deficiency in the Pathogenesis of Cardiovascular and Cerebrovascular Diseases

Deficiency in vitamin D (VitD), a lipid-soluble vitamin and steroid hormone, affects approximately 24% to 40% of the population of the Western world. In addition to its well-documented effects on the musculoskeletal system, VitD also contributes importantly to the promotion and preservation of cardiovascular health via modulating the immune and inflammatory functions and regulating cell proliferation and migration, endothelial function, renin expression, and extracellular matrix homeostasis. This brief overview focuses on the cardiovascular and cerebrovascular effects of VitD and the cellular, molecular, and functional changes that occur in the circulatory system in VitD deficiency (VDD). It explores the links among VDD and adverse vascular remodeling, endothelial dysfunction, vascular inflammation, and increased risk for cardiovascular and cerebrovascular diseases. Improved understanding of the complex role of VDD in the pathogenesis of atherosclerotic cardiovascular diseases, stroke, and vascular cognitive impairment is crucial for all cardiologists, dietitians, and geriatricians, as VDD presents an easy target for intervention.

Sex differences in vitamin D metabolism, serum levels and action

The ubiquity of vitamin D metabolising enzymes and vitamin D receptors in mammalian organisms suggests that vitamin D has pleiotropic effects. There are quite a few studies indicating the anticancer, cardioprotective and antidiabetic effects of vitamin D; however, the best-documented actions of vitamin D are the regulation of Ca-phosphate balance and its effect on immune function.Vitamin D levels in organisms are modulated by many environmental and non-environmental factors. One potential factor that may influence vitamin D levels and effects is the sex of the individuals studied. This review focuses on the scientific evidence indicating different synthesis and metabolism of vitamin D in females and males, mainly from PubMed database sources. The article verifies the sex differences in vitamin D levels reported around the world. Moreover, the different effects of vitamin D on the musculoskeletal, cardiovascular, nervous and immune systems, as well as cancer in males and females, were discussed.Most studies addressing sex differences in vitamin D levels and effects are observational studies with conflicting results. Therefore, carefully designed clinical trials and experiments on animal models should be carried out to determine the role of non-environmental factors that may differentiate vitamin D levels in females and males.

Metformin and vitamin D modulate adipose-derived stem cell differentiation towards the beige phenotype

Adipose-derived stem cells (ADSCs) represent an ideal stem cell population for regenerative medicine. ADSC adipogenic differentiation is controlled by the activation of a specific transcriptional program, including epigenetic factors and key adipogenic genes. Under certain conditioned media, ADSCs can differentiate into several phenotypes. We previously demonstrated that bioactive molecules could counteract lipid accumulation and regulate adipogenesis, acting on inflammation and vitamin D metabolism. In the present paper, we aimed at evaluating the effect of metformin and vitamin D in targeting ADSC differentiation towards an intermediate phenotype, as beige adipocytes. We exposed ADSCs to different conditioned media and then we evaluated the levels of expression of main markers of adipogenesis, aP2, LPL and ACOT2. We also analysed the gene and protein expression of thermogenic UCP1 protein, and the expression of PARP1 and the beige specific marker TMEM26. Our results showed a novel effect of metformin and vitamin D not only in inhibiting adipogenesis, but also in inducing a specific ‘brown-like’ phenotype. These findings pave the way for their possible application in the control of de novo lipogenesis useful for the prevention of obesity and its related metabolic disorders.

Heterozygous Loss of KRIT1 in Mice Affects Metabolic Functions of the Liver, Promoting Hepatic Oxidative and Glycative Stress

KRIT1 loss-of-function mutations underlie the pathogenesis of Cerebral Cavernous Malformation (CCM), a major vascular disease affecting the central nervous system (CNS). However, KRIT1 is also expressed outside the CNS and modulates key regulators of metabolic and oxy-inflammatory pathways, including the master transcription factor FoxO1, suggesting a widespread functional significance. Herein, we show that the KRIT1/FoxO1 axis is implicated in liver metabolic functions and antioxidative/antiglycative defenses. Indeed, by performing comparative studies in KRIT1 heterozygous (KRIT1^+/−) and wild-type mice, we found that KRIT1 haploinsufficiency resulted in FoxO1 expression/activity downregulation in the liver, and affected hepatic FoxO1-dependent signaling pathways, which are markers of major metabolic processes, including gluconeogenesis, glycolysis, mitochondrial respiration, and glycogen synthesis. Moreover, it caused sustained activation of the master antioxidant transcription factor Nrf2, hepatic accumulation of advanced glycation end-products (AGEs), and abnormal expression/activity of AGE receptors and detoxifying systems. Furthermore, it was associated with an impairment of food intake, systemic glucose disposal, and plasma levels of insulin. Specific molecular alterations detected in the liver of KRIT1^+/− mice were also confirmed in KRIT1 knockout cells. Overall, our findings demonstrated, for the first time, that KRIT1 haploinsufficiency affects glucose homeostasis and liver metabolic and antioxidative/antiglycative functions, thus inspiring future basic and translational studies.

Effects of dietary vitamin D3 supplementation on the growth performance, tissue Ca and P concentrations, antioxidant capacity, immune response and lipid metabolism in Litopenaeus vannamei larvae

An 8-week feeding trial was conducted to investigate the effects of dietary vitamin D3 supplementation on the growth performance, tissue Ca and P concentrations, antioxidant capacity, immune response and lipid metabolism in Litopenaeus vannamei larvae. A total of 720 shrimp (initial weight 0·50 ± 0·01 g) were randomly distributed into six treatments, each of which had three duplicates of forty shrimp per duplicate. Six isonitrogenous and isolipidic diets were formulated to contain graded vitamin D3 (0·18, 0·23, 0·27, 0·48, 0·57 and 0·98 mg/kg of vitamin D3, measured) supplementation levels. The results revealed that L. vannamei fed diet containing 0·48 mg/kg of vitamin D3 achieved the best growth performance. Compared with the control group, supplementing 0·48 mg/kg of vitamin D3 significantly increased (P < 0·05) the activities of catalase, total antioxidative capacity, alkaline phosphatase and acid phosphatase in serum and hepatopancreas. Expression levels of antioxidant and immune-related genes were synchronously increased (P < 0·05). Carapace P and Ca concentrations were increased (P < 0·05) with the increased vitamin D3 supplementation levels. Further analysis of lipid metabolism-related genes expression showed that shrimp fed 0·48 mg of vitamin D3 per kg diet showed the highest value in the expression of lipid synthesis-related genes, while shrimp fed 0·98 mg of vitamin D3 per kg diet showed the highest value in the expression of lipolysis-related genes. In conclusion, the results of present study indicated that dietary supplementation of 0·48 mg/kg of vitamin D3 could increase Ca and P concentrations, improve antioxidant capacity and immune response, and influence lipid metabolism in L. vannamei.

Vitamin D supplementation and risk of stroke: A meta-analysis of randomized controlled trials

Background

Previous observational studies have supported the hypothesis that vitamin D supplementation protects against stroke. However, several current intervention studies contradict this observation. Therefore, we conducted a meta-analysis to investigate further the association between vitamin D supplementation and the risk of stroke.

Methods

This meta-analysis was conducted in accordance with the PRISMA statement and included all the randomized controlled trials (RCTs) that analyzed the relationship between vitamin D supplementation and the risk of stroke. A literature search strategy was established, and the following Medical Search Terms (MeSH) were used: “vitamin D,” “Calcitriol,” “Calcifediol,” “Cholecalciferol,” “25-Hydroxyvitamin D 2,” “ergocalciferols,” “stroke,” and stroke-derived terms. We searched for articles published before January 2022 in several databases, namely, PubMed, Web of Science, EMBASE, and The Cochrane Library. We also reviewed references included in relevant published meta-analyses and searched the http://www.ClinicalTrials.gov website for additional RCTs. The Q test and I2 were utilized to assess the degree of heterogeneity among the studies. Review Manager 5.3 and STATA16.0 software programs were used to assess the literature quality and perform statistical analyses.

Results

In total, twenty-four RCTs (86,202 participants) were included. There was no statistical heterogeneity among the RCTs (I2 = 0.0%, P = 0.94) included in this meta-analysis. We determined that vitamin D supplementation was not associated with a reduced risk of stroke compared with the placebo (RR = 1.02, 95% CI: 0.93–1.13, P = 0.65). In total, 10 studies only included women, and 14 studies included women and men among the 24 RCTs. Therefore, we performed a subgroup analysis based on sex. After the subgroup analysis, the effect remained statistically insignificant (mixed-sex group: RR = 1.06, 95% CI: 0.93–1.22, P = 0.37, women group: RR = 0.98, 95% CI: 0.86–1.13, P = 0.80). The results were generally comparable, based on age, body mass index (BMI), follow-up period, baseline 25-hydroxyvitamin D (25(OH)D) levels, the designated endpoint, latitude, vitamin D dosage, type of vitamin D administered, and an absence or presence of concurrent calcium supplementation (P &gt; 0.05).

Conclusion

Our study revealed that additional vitamin D supplementation did not reduce the risk of stroke. Therefore, additional RCTs of similar design should not be encouraged to assess any association between vitamin D supplementation and reduced stroke risk.

The effect of iron dextran on vitamin D3 metabolism in SD rats

BACKGROUND

Iron and vitamin D (VD) is essential to health. Previous studies have shown that iron homeostasis has a potential effect on VD metabolism, but the mechanism is not fully understood.

OBJECTIVES

To explore the relationship between VD metabolism and iron metabolism, as well as the regulatory mechanism of iron on VD metabolism.

METHODS

40 male rats were fed adaptively for 7 days and randomly divided into control (C, n = 6 normal diet) group and model (M, n = 24 iron deficient diet) by simple randomization, the latter was used to establish iron deficiency anemia (IDA) model. After 6 weeks of feeding, the M group was randomly divided into: iron deficiency group (DFe), low iron group (LFe), medium iron group (MFe) and high iron group (HFe) by block randomization. Different doses of iron dextran (based on iron content (100 g·bw·d)): 0, 1.1, 3.3 and 9.9 mg) were given respectively. After 4 weeks, the rats were anesthetized with 8% chloral hydrate, Blood (collected from the abdominal aorta), liver and kidney tissues were collected. The serum and tissues were separately packed and frozen at -80℃ for testing.

RESULTS

The results showed that the levels of hemoglobin (Hb), red blood cell (RBC), serum iron (SI), liver iron, and kidney iron in DFe group were lower than those in the other four groups, while the levels of total iron-binding capacity (TIBC), transferrin (TF) and transferrin receptor (Tfr) in DFe group were higher than those in other groups; The serum levels of 25-(OH)D₃ and 1,25-(OH)₂D₃ in DFe group were significantly lower than those in C group (P < 0.05). The correlation analysis showed that the levels of 25-(OH)D₃ and 1,25-(OH)₂D₃ were negatively correlated with TIBC, TF and Tfr no correlation with SI. Western blotting, immunofluorescence, and q-PCR results showed that compared with C group, the protein and gene expressions of CYP2R1, CYP27A1, and CYP24A1 in DFe group were down-regulated, and the expression of CYP27B1 protein and gene was up-regulated in DFe group.

CONCLUSION

Iron may be involved in the metabolism of VD₃ by regulating the expression of VD₃ hydroxylase, suggesting that appropriate iron supplementation might promote the activation of VD₃.

Surrogate biomarkers of outcome for wake-up ischemic stroke

Background

Wake-up ischemic stroke (IS) has been usually excluded from acute stroke therapy options for being outside of the safe treatment window. We identified risk factors, and clinical or molecular biomarkers that could be therapeutic targets for wake-up stroke prevention, thus hopefully leading to a decrease in its mortality and disability in medium to long-term outcome.

Methods

4251 ischemic stroke (IS) patients from a prospectively registered database were recruited; 3838 (90.3%) had known onset-symptom time, and 413 (9.7%) were wake-up strokes. The main endpoint was to analyze the association between different serum biomarkers with wake-up IS episodes and their progression. Leukocytes count, serum levels of C-reactive protein, fibrinogen, interleukin 6 (IL-6), and vitamin D were analyzed as inflammation biomarkers; N-terminal pro-B-type Natriuretic-Peptide and microalbuminuria, used as atrial/endothelial dysfunction biomarkers; finally, glutamate levels as excitotoxicity biomarker. In addition, demographic, clinical and neuroimaging variables associated with the time-evolution of wake-up IS patients and functional outcome at 3 months were evaluated. Good and poor functional outcome were defined as mRS ≤2 and mRS > 2 at 3 months, respectively.

Results

Wake-up IS showed a poorer outcome at 3-months than in patients with known on-set-symptom time (59.1% vs. 48.1%; p < 0.0001). Patients with wake-up IS had higher levels of inflammation biomarkers; IL-6 levels at admission (51.5 ± 15.1 vs. 27.8 ± 18.6 pg/ml; p < 0.0001), and low vitamin D levels at 24 h (5.6 ± 5.8 vs. 19.2 ± 9.4 ng/ml; p < 0.0001) are worthy of attention. In a logistic regression model adjusted for vitamin D, OR was 15.1; CI 95%: 8.6–26.3, p < 0.0001. However, we found no difference in vitamin D levels between patients with or without clinical-DWI mismatch (no: 18.95 ± 9.66; yes: 17.84 ± 11.77 ng/mL, p = 0.394). No difference in DWI volume at admission was found (49.3 ± 96.9 ml in wake-up IS patients vs. 51.7 ± 98.2 ml in awake IS patients; p = 0.895).

Conclusions

Inflammatory biomarkers are the main factors that are strongly associated with wake-up IS episodes. Wake-up IS is associated with lower vitamin D levels. These data indicate that vitamin D deficiency could become a therapeutic target to reduce wake-up IS events.

Vitamin D status in the active duty Navy military personnel: protocol for a systematic review

INTRODUCTION

Vitamin D is critical for bone health and its deficiency has been linked to increased incidence and severity of multiple diseases. Even so, vitamin D inadequacy is a major public health problem worldwide. The main source of vitamin D is endogenous cutaneous synthesis through exposure to solar ultraviolet B radiation, which is influenced by several factors, including occupational. The active duty Navy military personnel may be prone to vitamin D inadequacy, but a worldwide overview of vitamin D status in this specific population is still lacking.

METHODS AND ANALYSIS

The CoCoPop mnemonic will be used for determining the inclusion criteria. Scopus, Web of Science and PubMed/Medline will be searched for all studies including 25-hydroxyvitamin D concentrations of the active duty Navy military personnel. Data extraction and quality assessment (Joanna Briggs Institute's and Downs and Black checklists) will be performed by two reviewers and data will be synthesised in narrative, tabular and map formats.

ETHICS AND DISSEMINATION

This study will not involve human or animal subjects and, thus, does not require ethics approval. The outcomes will be disseminated via publication in a peer-reviewed scientific journal and presentation at a scientific conference.

PROSPERO REGISTRATION NUMBER

CRD42022287057.

Low-Molecular-Weight Synthetic Antioxidants: Classification, Pharmacological Profile, Effectiveness and Trends

Mounting research has been performed and published on natural antioxidants, more so than on synthetic ones, as key molecules that control oxidative damage and its pathway to disease. Since the discovery of vitamins, various fully synthetic or natural-identical compounds have been developed as stable small molecules translated into constantly active and completely controlled products which are widely exploited in the food and pharmaceutical industries. There is currently a debate within the literature about their mechanism of action, bioavailability, safety and real benefit for human health. Using a semiquantitative method and eligible criteria of selection, this review aimed to provide a very useful classification of antioxidants and a comprehensive cross-disciplinary description of 32 approved synthetic/natural-identical antioxidants, in terms of regulatory, antioxidant mechanism of action, safety issues, pharmacological properties, effectiveness in human health, timeline and future trends. Enriched interpretation of the data was obtained from summary bibliometrics, useful to portray the “good antioxidant” within the period 1966–2021 and, hopefully, to encourage further research.

Formulation Strategies for Improving the Stability and Bioavailability of Vitamin D-Fortified Beverages: A Review

Vitamin D is a lipophilic bioactive that plays an important role in bone health. Fortification of beverages, such as milk, fruit juices, teas, and vegetable drinks, could be an efficient strategy to prevent vitamin D deficiency and its associated effects on health. This review summarizes the current understanding of beverage fortification strategies with vitamin D and the resulting effects on the stability, bioaccessibility, and sensory properties of the formulated products. The direct addition technique has been the conventional approach to fortifying beverages. In addition, encapsulation has been pointed out as a desirable delivery approach to increase stability, preserve bioactivity, and enhance the absorption of vitamin D in beverage systems. The literature reports the potential applicability of several methods for encapsulating vitamin D in beverages, including spray drying, micro/nanoemulsions, nanostructured lipid carriers, liposomes, and complexation to polymers. Some of these delivery systems have been assessed regarding vitamin D stability, but there is a lack of kinetic data that allow for the prediction of its stability under industrial processing conditions. Moreover, in some cases, the applicability of some of these delivery systems to real beverages as well as the in vivo efficacy were not evaluated; thus, fortification strategies with a global outreach are lacking.

Vitamin D as a modifiable risk factor, predictor, and theoretical therapeutic agent for vasospasm in spontaneous subarachnoid hemorrhage

Delayed deterioration associated with cerebral vasospasm (CVS) is a feared complication after spontaneous subarachnoid hemorrhage (SAH) and is one of the leading causes of death in patients with intracranial hemorrhage. The pathophysiology of vasospasm is complex and not fully understood, involving multiple inflammatory pathways in addition to vasoconstriction induced ischemia. Current treatment with anti-inflammatory or vasodilatory medications has been met with limited success and has not led to a decrease in vasospastic associated mortality prompting continued investigation of potential treatment options. The active form of vitamin D, 1,25-dihydroxyvitamin D₃ (1,25-VitD3), is a hormone with downstream effects that induce anti-inflammatory pathways, promote nitric oxide (NO) induced vasodilation, and lead to neuroprotective-gene expression, which may be useful in mitigating the vascular pathogenesis associated with CVS. A high prevalence of vitamin D deficiency has been identified in patients admitted with SAH. Low vitamin D levels in patients, as determined by time of year, has also been correlated to an increased incidence and severity of CVS. Further, the therapeutic usefulness of 1,25-VitD3 has been demonstrated in animal models leading to a decreased incidence of CVS but has yet to be thoroughly investigated in human studies. In this review, we will discuss the findings that suggest the potential of utilizing vitamin D as a predictive indicator, method of prevention, and or treatment option for CVS in patients following spontaneous SAH.

Narrative review of recent studies on the role of vitamin D in the prevention of cardiac and renal risk and additional considerations for COVID-19 vulnerability

The role of vitamin D in maintaining a healthy cardiovascular (CV) and the renal system has received increasing attention. Low vitamin D levels are associated with the incidence of hypertension, cardiac remodeling, and chronic congestive heart failure. Low vitamin D levels also influence renal disease progression and albuminuria deterioration. Moreover, recent research indicates that vitamin D deficiency can be a potential risk factor for coronavirus disease-19 (COVID-19) infection and poorer outcomes. Data are inconclusive as to whether supplementation with vitamin D agents reduces CV disease risk or COVID-19 severity. Conversely, in patients with kidney disease, vitamin D supplementation is associated with improved kidney function and albuminuria. This narrative review considers recent data on the effects of vitamin D on the CV and renal system, as well as its possible role regarding COVID-19 complications.

1α,25-Dihydroxyvitamin D3 promotes angiogenesis by alleviating AGEs-induced autophagy

Diabetes mellitus (DM) induces abnormal angiogenesis and results in multiple chronic vascular complications. Previous studies showed that advanced glycation end products (AGEs) up-regulated in diabetic patients and induced a series of cellular effects such as oxidative stress, inflammation, and autophagy. 1α,25-Dihydroxyvitamin D3 (1,25D), a hormonal form of vitamin D, proved to be beneficial for vascular diseases. However, the underlying mechanism of 1,25D in angiogenesis in DM remains unclear. Using CCK8 assay and transwell assay, we found that 1,25D could partly ameliorate impaired proliferation and migration ability of endothelial cells (ECs) induced by AGEs (200 μg/mL). Furthermore, tube formation assay, Western blot, and real-time qPCR assay were conducted to demonstrate that AGEs impaired angiogenetic ability, and that angiogenesis-related gene expression (i.e., VEGFA, VEGFB, VEGFR1, VEGFR2, TGFβ1, MMP2, MMP9) in ECs and 1,25D could promote angiogenesis and angiogenetic markers expression. By using DCFH-DA, ELISA, and Western blot assay, we also found that AGEs-induced oxidative stress impaired angiogenic ability of ECs, and 1,25D alleviated angiogenesis dysfunction by inhibiting oxidative stress. Of note, AGEs-induced excessive autophagy was found to impair angiogenesis. We elucidated that the detrimental autophagy is modulated by 1,25D and AGEs via PI3K/Akt pathway. Observed together, our findings illustrated that AGEs-induced oxidative stress and autophagy resulted in angiogenic disorder and 1,25D improved angiogenesis by restraining excessive autophagy and oxidative stress, providing a novel insight for the treatment of vascular complications in DM.

The role of rehabilitation and vitamin D supplementation on motor and psychological outcomes in poststroke patients

Post-Stroke depression affects between 12% and 72% of patients who have suffered a stroke. The association between low serum levels of 25-hydroxyvitamin D (25(OH) D) and increased risk of depression is reported in both stroke and non-stroke patients. Similarly, high 25(OH) D levels might be associated with greater functional improvement during rehabilitation program.We wanted to investigate the effects of an intensive rehabilitation on poststroke outcomes. We wondered if the daily rehabilitation of motor and cognitive functions could also have an effect on mood and functional abilities in addition to or as an alternative to vitamin D supplementation.We conducted a 12-week, randomized trial, double blind, parallel, monocentric clinical trial of 40 patients undergoing intensive neuro-rehabilitation treatment at a specialized care facility for ischemic or hemorrhagic brain stroke. Participants were randomly assigned, in a 1:1 ratio, to 1 of 2 parallel groups: in the experimental group, 2000 IU/day of oral cholecalciferol was administered; in the control group patients were not taking vitamin D supplementation. Patients underwent a text evaluation to investigate psychological and motor outcomes.Significant intra-group difference in outcomes measures was found but not between control group and experimental group. In the vitamin D group, we highlighted significant differences between T0 and T1 in calcium (P < .001), vitamin D (P < .001), in Montgomery Aasberg Depression Rating Scale (P = .001), and in Functional Independent Measures (P < .001). In the health control group, we found a significant difference in calcium (P = .003), vitamin D (P < .001), Montgomery Aasberg Depression Rating Scale (P = 0.006), in general self-efficacy (P = .009), and in Functional Independent Measures (P < .001).Our results show that the beneficial effect on mood and functional recovery is mainly due to neurorehabilitation rather than vitamin D supplementation.

Association of Serum 25-Hydroxyvitamin D Concentrations With All-Cause and Cause-Specific Mortality Among Adult Patients With Existing Cardiovascular Disease

Background: Vitamin D insufficiency and deficiency are common in patients with cardiovascular disease (CVD). We aimed to prospectively examine the associations of serum 25-hydroxyvitamin D [25(OH)D] concentrations with all-cause and cause-specific mortality among adult patients with existing CVD.

Methods: We included 37,079 patients with CVD from the UK Biobank study, a prospective cohort of half a million participants aged 40–69 years. We defined patients with CVD as those who suffered coronary heart disease, atrial fibrillation, heart failure, or stroke. The associations of serum 25(OH)D concentration with all-cause and cause-specific mortality were examined by using multivariable Cox regression models and competing risk analyses.

Results: Among 37,079 patients with CVD at baseline, 57.5% were subjected to vitamin D deficiency (i.e., 25[OH]D <50 nmol/L). During a median follow-up of 11.7 years, 6,319 total deaths occurred, including 2,161 deaths from CVD, 2,230 deaths from cancer, 623 deaths from respiratory disease, and 1,305 other-cause deaths. We observed non-linear inverse associations for all-cause, cancer, respiratory disease, and other-cause mortality (P-non-linearity <0.01) and approximately linear inverse associations for CVD mortality (P-non-linearity = 0.074). Among CVD patients with vitamin D deficiency, per 10 nmol/L increment in serum 25(OH)D concentrations was associated with an 12% reduced risk for all-cause mortality and 9% reduced risk for CVD mortality.

Conclusion: Among patients with existing CVD, increasing levels in serum 25(OH)D were independently associated with a decreased risk of all-cause and cause-specific mortality. These findings suggest that elevated serum 25(OH)D concentration benefits CVD patients with vitamin D deficiency.

Neurosteroids: A novel promise for the treatment of stroke and post-stroke complications

Stroke is the primary reason for death and disability worldwide, with few treatment strategies to date. Neurosteroids, which are natural molecules in the brain, have aroused great interest in the field of stroke. Neurosteroids are a kind of steroid that acts on the nervous system, and are synthesized in the mitochondria of neurons or glial cells using cholesterol or other steroidal precursors. Neurosteroids mainly include estrogen, progesterone (PROG), allopregnanolone, dehydroepiandrosterone (DHEA), and vitamin D (VD). Most of the preclinical studies have confirmed that neurosteroids can decrease the risk of stroke, and improve stroke outcomes. In the meantime, neurosteroids have been shown to have a positive therapeutic significance in some post-stroke complications, such as epilepsy, depression, anxiety, cardiac complications, movement disorders, and post-stroke pain. In this review, we report the historical background, modulatory mechanisms of neurosteroids in stroke and post-stroke complications, and emphasize on the application prospect of neurosteroids in stroke therapy.

The Role of Micronutrients to Support Immunity for COVID-19 Prevention

The World Health Organization declared the novel coronavirus, named as SARS-CoV-2, as a global pandemic in early 2020 after the disease spread to more than 180 countries leading to tens of thousands of cases and many deaths within a couple of months. Consequently, this paper aims to summarize the evidence for the relationships between nutrition and the boosting of the immune system in the fight against the disease caused by SARS-CoV-2. This review, in particular, assesses the impact of vitamin and mineral supplements on the body's defence mechanisms against SARS-CoV-2. The results revealed that there is a strong relationship between the ingestion of biological ingredients like vitamins C-E, and minerals such as zinc, and a reduction in the effects of coronavirus infection. These can be received from either nutrition rich food sources or from vitamin supplements. Furthermore, these macromolecules might have roles to play in boosting the immune response, in the healing process and the recovery time. Hence, we recommend that eating healthy foods rich in vitamins C-E with zinc and flavonoids could boost the immune system and consequently protect the body from serious infections.

GRAPHICAL ABSTRACT

Polymorphisms in genes related to oxidative stress and inflammation: Emerging links with the pathogenesis and severity of Cerebral Cavernous Malformation disease

Cerebral Cavernous Malformation (CCM) is a cerebrovascular disease of genetic origin affecting 0.5% of the population and characterized by abnormally enlarged and leaky capillaries that predispose to seizures, neurological deficits, and intracerebral hemorrhage (ICH). CCM occurs sporadically or is inherited as dominant condition with incomplete penetrance and highly variable expressivity. Three disease genes have been identified: KRIT1 (CCM1), CCM2 and CCM3. Previous results demonstrated that loss-of-function mutations of CCM genes cause pleiotropic effects, including defective autophagy, altered reactive oxygen species (ROS) homeostasis, and enhanced sensitivity to oxidative stress and inflammatory events, suggesting a novel unifying pathogenetic mechanism, and raising the possibility that CCM disease onset and severity are influenced by the presence of susceptibility and modifier genes. Consistently, genome-wide association studies (GWAS) in large and homogeneous cohorts of patients sharing the familial form of CCM disease and identical mutations in CCM genes have led to the discovery of distinct genetic modifiers of major disease severity phenotypes, such as development of numerous and large CCM lesions, and susceptibility to ICH. This review deals with the identification of genetic modifiers with a significant impact on inter-individual variability in CCM disease onset and severity, including highly polymorphic genes involved in oxidative stress, inflammatory and immune responses, such as cytochrome P450 monooxygenases (CYP), matrix metalloproteinases (MMP), and Toll-like receptors (TLR), pointing to their emerging prognostic value, and opening up new perspectives for risk stratification and personalized medicine strategies.

Nutritional Supplementation of Naturally Occurring Vitamin D to Improve Hemorrhagic Stroke Outcomes

Vitamin D deficiency, if left untreated, is associated with bone disorders, cardiovascular damage, and an increased risk of ischemic stroke. While there are various nutritional options for the natural intake of vitamin D, we hope to elucidate the potential mechanisms dietary vitamin D may play in hemorrhagic stroke pathology. This scoping review outlines findings from studies relevant to the biochemical activity of vitamin D, the impact of vitamin D deficiency on hemorrhagic stroke outcomes, and the potential benefit of nutritional vitamin D on hemorrhagic stroke outcomes. Here, we analyze the relevant factors that can lead to vitamin D deficiency, and subsequently, a higher risk of hemorrhagic stroke incidence with worsened subsequent outcomes. The neuroprotective mechanisms through which vitamin D works to attenuate hemorrhagic stroke onset and post-stroke outcomes have not yet been thoroughly examined. However, researchers have proposed several potential protective mechanisms, including reduction of blood brain barrier disturbance by inhibiting the production of reactive oxygen species, mitigation of inflammation through a reduction of levels of proinflammatory cytokines, and prevention of cerebral vasospasm and delayed cerebral ischemia following subarachnoid hemorrhage and intracerebral hemorrhage. While more research is needed and there are limitations to vitamin D supplementation, vitamin D as a whole may play a significant role in the dynamics of hemorrhagic stroke. Further research should focus on expanding our understanding of the neuroprotective capacity and mechanisms of vitamin D, as well as how vitamin D supplementation could serve as an effective course of treatment of hemorrhagic strokes.

Calcitriol attenuates the cytotoxicity induced by aluminium phosphide via inhibiting mitochondrial dysfunction and oxidative stress in rat isolated cardiomyocytes

These days, poisoning with aluminium phosphide (AlP), is one of the main health threats in human societies. Previous studies have been reported that cardiotoxicity induced by AlP, via mitochondrial dysfunction and oxidative stress is the main cause of death in victims. On the other, collectively, multiple lines of evidence strongly suggest that calcitriol has mitochondrial protective and antioxidant effects. Therefore, we assumed that calcitriol could presumably ameliorate AlP-induced oxidative stress and mitochondrial dysfunction in cardiomyocytes. Mitochondria and cardiomyocytes were isolated by differential centrifugation and collagenase perfusion respectively from rat heart. The isolated cardiomyocytes and mitochondria were cotreated with different concentrations of calcitriol (0.2, 0.4 and 1 μg/ml) and AlP (20 μg/ml) for 3 h. The parameters of cellular toxicity including; cytotoxicity, reactive oxygen species (ROS) formation, malondialdehyde (MDA) level, mitochondria membrane potential (ΔΨm) collapse, lysosomal membrane integrity, the level of oxidized and reduced glutathione (GSH and GSSG), and mitochondrial toxicity parameters including; succinate dehydrogenase (SDH) activity and mitochondrial swelling were analyzed using biochemical and flow cytometric evaluations. Administration of AlP significantly increased cytotoxicity, GSH depletion, cellular ROS formation, MDA level, mitochondrial and lysosomal dysfunction in isolated cardiomyocytes. In isolated mitochondria, AlP decreased SDH activity and mitochondrial swelling. The cotreatment of isolated cardiomyocytes and mitochondria with calcitriol (0.4 and 1 μg/ml) and AlP (20 μg/ml) showed the ability to reduce the toxic effects of AlP. These findings suggest a potential therapeutic role of calcitriol in protecting cardiomyocytes and cardiac mitochondria from oxidative damage induced by AlP. According to the results, calcitriol exerted ameliorative effects against AlP-induced cytotoxicity and mitochondrial toxicity, and the effect was attributed to the antioxidant properties.

Protective Effects of 1,25 Dihydroxyvitamin D3 against High-Glucose-Induced Damage in Human Umbilical Vein Endothelial Cells Involve Activation of Nrf2 Antioxidant Signaling

AIM

To explore the protective effects and related mech-anisms of 1,25 dihydroxyvitamin D3 (1,25(OH)2D3) on en-dothelial dysfunction under hyperglycemic conditions.

METHODS

Cultured human umbilical vein endothelial cells (HUVECs) were treated with normal glucose (glucose concentration of 5.5 mmol/L), high glucose (glucose concentration of 33 mmol/L), and high glucose plus 1,25(OH)2D3, respectively. Cell viability and apoptosis, intracellular reactive oxygen species (ROS) and nitric oxide (NO) contents, antioxidant enzyme activities, proinflammatory cytokine mRNA levels, and expression levels of proteins involved were measured.

RESULTS

High glucose decreased HUVEC viability, promoted ROS production and apoptosis, and reduced NO generation, which was associated with decreased activities of antioxidant enzymes and increased levels of proinflam-matory cytokines. 1,25(OH)2D3 treatment enhanced HUVEC viability, attenuated ROS generation and apoptosis, and -increased NO production, which was accompanied by -enhanced antioxidant enzyme activities and reduced -proinflammatory factors. Mechanically, 1,25(OH)2D3 promoted nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) in a vitamin D receptor (VDR)-dependent manner, and Nrf2 siRNA abolished the antioxidative and -anti-inflammatory effects of 1,25(OH)2D3.

CONCLUSIONS

1,25(OH)2D3 attenuates high-glucose-induced endothelial oxidative injury through upregulation of the Nrf2 antioxidant pathway in a VDR-dependent manner.