Vitamin D status is linked to biomarkers of oxidative stress, inflammation, and endothelial activation in obese children

Associations between Aging and Vitamin D Status with Whole-Body Nitric Oxide Production and Markers of Endothelial Function

BACKGROUND

Aging and vitamin D deficiency have been associated with reduced nitric oxide (NO) synthesis and impaired endothelial function (EF) but the evidence in humans remains weak.

OBJECTIVES

Two independent cross-sectional studies were designed to evaluate the association between age, sex, and plasma vitamin D concentrations with physiological and biochemical biomarkers of NO synthesis and EF in young and older healthy participants (Study 1) and in overweight and obese postmenopausal females (Study 2).

METHODS

In Study 1, 40 young (20-49 y) and older (50-75 y) males and females (10 participants per age and sex group) were included. Resting blood pressure and ear-to-finger peripheral pulse wave velocity (PWV) were measured. A stable-isotopic method was used to determine whole-body NO production. Plasma 25-hydroxyvitamin D (25(OH)D), nitrate, nitrite, and asymmetric dimethylarginine (ADMA) concentrations were determined. In Study 2, 80 older overweight and obese females (age 61.2 ± 6.2 y, body mass index 29.5 ± 4.4 kg/m2) were recruited. Postocclusion reactive hyperemia (PORH) and peripheral PWV were measured. Plasma concentrations of 25(OH)D, nitrate, cyclic guanosine monophosphate, 3-nitrotyrosine (3-NT), endothelin-1, vascular endothelial growth factor, and ADMA were determined.

RESULTS

In Study 1, whole-body NO production was significantly greater in young compared with older participants (0.61 ± 0.30 μmol·h-1·kg-1 compared with 0.39 ± 0.10 μmol·h-1·kg-1, P = 0.01) but there was no evidence of a sex difference (P = 0.81). Plasma 25(OH)D concentration was not associated with PWV (r = 0.18, P = 0.28) or whole-body NO production (r = -0.20, P = 0.22). Plasma ADMA concentration was associated positively with age (r = 0.35, P = 0.03) and negatively with whole-body NO production (r = -0.33, P = 0.04). In Study 2, age was associated with lower PORH (r = -0.28, P = 0.02) and greater ADMA concentrations (r = 0.22, P = 0.04). Plasma 25(OH)D concentration was inversely associated with 3-NT concentrations (r = -0.31, P = 0.004).

CONCLUSIONS

Older age was associated with lower whole-body NO production. Plasma vitamin D concentrations were not associated with NO production or markers of EF but showed a weak, significant correlation with oxidative stress in postmenopausal overweight females.

The role of the transsulfuration pathway in spermatogenesis of vitamin D deficient mice

Vitamin D deficiency is a global health problem and has been linked to defective spermatogenesis and male infertility. In this study, we aimed to investigate the main enzymes involved in the transsulfuration pathway of 1-carbon metabolism, and spermatogenesis function. Therefore, sixteen male C57 mice were addressed to a control (standard diet) or vitamin D deficient (VDD) diet for 14 weeks. The results show that compared to the standard diet, VDD increased final body weight and reduced sperm quality, caused damage to the testicular structure, and decreased the serum levels of testosterone. In addition, serum concentrations of homocysteine, vitamin B12, and sperm oxidative stress markers increased. In testicular tissues, the CBS and CSE protein levels were down-regulated whereas HO-1 was up-regulated at both mRNA and protein expression levels. Within a mice deprivation model, VDD deeply suppressed testosterone and impaired spermatogenesis with oxidative stress-mediated mechanisms. The effects of the deprivation appeared to be at least in part independent of genomic and receptor-mediated vitamin D actions and suggest a specific impairment of the alternative transsulfuration pathway.

Vitamin D and biomarkers of inflammation and oxidative stress among pregnant women: a systematic review of observational studies

OBJECTIVE

This systematic review aimed to map the evidence evaluated the relationship between vitamin D and redox and inflammatory status during gestation.

METHODS

Three databases (PubMed/MEDLINE, Scopus, and Web of Science (WoS)) and reference list of included documents were searched for related observational studies published until 2nd October 2023. To determine the quality of the selected observational studies, the Newcastle-Ottawa Scale (NOS) was used.

RESULTS

After a primary search of three databases, 19492records were appeared. When duplicates and irrelevant documents were removed, 14 articles were found to have eligible criteria. The design of the identified studies was cross-sectional, case-control and cohort. Evidence showed an adverse association between 25(OH)D and the biomarkers of inflammation, such as high-sensitivity C-reactive protein (hs-CRP), Interleukin-1beta (IL-1β), Interleukin-6 (IL-6), and tumor necrosis factor- alfa (TNF-α) during pregnancy. On the contrary, some studies represented that 25(OH)D positively correlated with hs-CRP in the cord blood. One study suggested a direct association between serum concentrations of 25(OH)D and Interleukin-8 (IL-8), macrophage inflammatory protein (MIP), and TNF-α levels in mothers with gestational diabetes mellitus (GDM). A case-control study showed that lower serum concentration of 25(OH)D positively correlated with total antioxidant capacity (TAC) levels in participants.

CONCLUSIONS

Evidence confirmed the supposition of the direct relationship between vitamin D levels and biomarkers with anti-inflammatory and anti-oxidative properties. However, the Existence of inconsistent evidence confirms the need for further studies in mothers with GDM and hypertensive disorders.

PROSPERO REGISTRATION CODE

CRD42020202600.

Vitamin D and autophagy in knee osteoarthritis: A review

Knee osteoarthritis (KOA), the highly prevalent degenerative disease affecting the joint, perpetually devastates the health of the elderly. Of various mechanisms known to participate in KOA etiology, apoptosis of chondrocytes is widely regarded as the primary cause of cartilage degradation. It has been suggested that the induction of autophagy in chondrocytes could potentially prolong the progression of KOA by modulating intracellular metabolic processes, which may be helpful for ameliorating chondrocyte apoptosis and eventual cartilage degeneration. Autophagy, a physiological process characterized by intracellular self-degradation, has been reportedly implicated in various pathologic conditions including KOA. Interestingly, vitamin D has been shown to regulate autophagy in human chondrocytes through multiple pathways, specifically AMPK/mTOR signaling pathway. This observation underscores the potential of vitamin D as a novel approach for restoring the functionality and survivability of chondrocytes in KOA. Supporting vitamin D's clinical significance, previous studies have demonstrated its substantial involvement in the symptoms and irregular joint morphology observed in KOA patients, strengthening potential therapeutic efficacy of vitamin D in treatment of KOA. Herein, the purpose of this review was to determine the mechanisms underlying the multi-processes of vitamin D implicated in autophagy in several cells including chondrocytes, which would bring unique insights into KOA pathogenesis.

Vitamin D3 supplementation improves spatial memory, muscle function, pain score, and modulates different functional physiological biomarkers in vitamin D3 deficiency diet (VDD)-induced rats model

BACKGROUND

Vitamin D Deficiency is recognized as a pandemic, which is associated with high mortality. An inadequate level of vitamin D is associated with autoimmune diseases, hypertension, and cancer. The study was aimed to assess the pharmacological effects of chronic vitamin D3 supplementation on the manipulation diet regiment of deprived cholecalciferol (vitamin D3 deficient diet, VDD) rats.

METHODS

Memory performance (Y-maze task), muscular function (muscle grip strength), and pain score (pressure application measurement meter) were measured. Functional biomarkers were measured using ELISA method in different matrix viz. in serum (parathyroid hormone; PTH, calcitonin, thyroxine, and C-reactive protein; CRP, 25-OH Vit D3), and in CSF (klotho and β-endorphin). 25-OH Vit D3 was also estimated in liver and kidney homogenate using ELISA. Vitamin D receptor (VDR) was measured spectrophotometrically in liver and adipose tissue.

RESULTS

VDD-induced rats showed a decrease in number of entries and time spent in the novel arm and spontaneous alternations in the Y-maze task. Significant improvements of neuromuscular function and pain score after addition of vitamin D3. In comparison to the VDD group, VDR expression (liver) and active metabolites of vitamin D3 (25-OH vit.D3) in serum were significantly higher by 48.23% and 280%, respectively. The PTH and CRP levels were significantly reduced by 32.5% and 35.27%, respectively, whereas calcitonin was increased by 36.67% compared with the VDD group. Klotho and β-endorphin expressions in cerebrospinal fluid were significantly elevated by 19.67% and 133.59%, respectively, compared to VDD group.

CONCLUSIONS

Overall, the results indicate that supplementation of cholecalciferol significantly improved spatial memory impairment, VDR expression, and may provide an opportunity to manage vitamin D deficiencies.

The Role of Vitamin D in Neuroprotection in Multiple Sclerosis: An Update

Multiple sclerosis (MS) is a complex neurological condition that involves both inflammatory demyelinating and neurodegenerative components. MS research and treatments have traditionally focused on immunomodulation, with less investigation of neuroprotection, and this holds true for the role of vitamin D in MS. Researchers have already established that vitamin D plays an anti-inflammatory role in modulating the immune system in MS. More recently, researchers have begun investigating the potential neuroprotective role of vitamin D in MS. The active form of vitamin D, 1,25(OH)₂D₃, has a range of neuroprotective properties, which may be important in remyelination and/or the prevention of demyelination. The most notable finding relevant to MS is that 1,25(OH)₂D₃ promotes stem cell proliferation and drives the differentiation of neural stem cells into oligodendrocytes, which carry out remyelination. In addition, 1,25(OH)₂D₃ counteracts neurodegeneration and oxidative stress by suppressing the activation of reactive astrocytes and M1 microglia. 1,25(OH)₂D₃ also promotes the expression of various neuroprotective factors, including neurotrophins and antioxidant enzymes. 1,25(OH)₂D₃ decreases blood-brain barrier permeability, reducing leukocyte recruitment into the central nervous system. These neuroprotective effects, stimulated by 1,25(OH)₂D₃, all enhance neuronal survival. This review summarizes and connects the current evidence supporting the vitamin D-mediated mechanisms of action for neuroprotection in MS.

The Role of Vitamins in the Pathogenesis of Asthma

Vitamins play a crucial role in the proper functioning of organisms. Disturbances of their levels, seen as deficiency or excess, enhance the development of various diseases, including those of the cardiovascular, immune, or respiratory systems. The present paper aims to summarize the role of vitamins in one of the most common diseases of the respiratory system, asthma. This narrative review describes the influence of vitamins on asthma and its main symptoms such as bronchial hyperreactivity, airway inflammation, oxidative stress, and airway remodeling, as well as the correlation between vitamin intake and levels and the risk of asthma in both pre- and postnatal life.

Vitamin D Determinants, Status, and Antioxidant/Anti-inflammatory-Related Effects in Cardiovascular Risk and Disease: Not the Last Word in the Controversy

Beyond its key role in calcium homeostasis, vitamin D has been found to significantly affect the cardiovascular (CV) system. In fact, low vitamin D levels have been associated with increased CV risk, as well as increased CV morbidity and mortality. The majority of effects of this molecule are related directly or indirectly to its antioxidative and anti-inflammatory properties. Generally, vitamin D insufficiency is considered for 25-hydroxyvitamin D (25(OH)D) levels between 21-29 ng/mL (corresponding to 52.5-72.5 nmol/L), deficiency as 25(OH)D levels less than 20 ng/mL (<50 nmol/L), and extreme deficiency as 25(OH)D less than 10 ng/mL (<25 nmol/L). However, the definition of an optimal vitamin D status, as defined by 25(OH)D, remains controversial for many extra-bone conditions, including CV disease. In this review, confounding factors affecting the 25(OH)D measurement and status will be discussed. In particular, available evidence on the mechanism and role of vitamin D in relation to CV risk and disease through its antioxidant effect will be reported, also facing the aspect regarding the debate on the minimum blood 25(OH)D level required to ensure optimal CV health.

Therapeutic potential of vitamin D against bisphenol A-induced spleen injury in Swiss albino mice

Bisphenol A (BPA), a ubiquitous plasticizer, is capable of producing oxidative splenic injury, and ultimately led to spleen pathology. Further, a link between VitD levels and oxidative stress was reported. Hence the role of VitD in BPA-induced oxidative splenic injury was investigated in this study. Sixty male and female Swiss albino mice (3.5 weeks old) were randomly divided into control and treated groups 12 mice in each (six males and six females). The control groups were further divided into sham (no treatment) and vehicle (sterile corn oil), whereas the treatment group was divided into VitD (2,195 IU/kg), BPA (50 μg/kg), and BPA+VitD (50 μg/kg + 2,195 IU/kg) groups. For six weeks, the animals were dosed intraperitoneally (i.p). One week later, at 10.5 weeks old, mice were sacrificed for biochemical and histological analyses. Findings showed BPA triggered neurobehavioral abnormalities and spleen injury with increased apoptotic indices (e.g. DNA fragmentation) in both sexes. A significant increase was found in lipid peroxidation marker, MDA in splenic tissue, and leukocytosis. Conversely, VitD treatment altered this scenario into motor performance preservation, reducing oxidative splenic injury with a decrease in the percent apoptotic index. This protection was significantly correlated with preserving leukocyte counts and reduced MDA levels in both genders. It can be concluded from the above findings that VitD treatment has an ameliorative effect on oxidative splenic injury induced by BPA, highlighting the continuous crosstalk between oxidative stress and the VitD signaling pathway.

The association of vitamin D status with oxidative stress biomarkers and matrix metalloproteinases in patients with knee osteoarthritis

Objective

The association of vitamin D status with osteoarthritis (OA) has been demonstrated previously. The current study was performed to examine the association of vitamin D status with oxidative stress markers and matrix metalloproteinases (MMPs) in patients with knee OA.

Methods

This case-control study was conducted on 124 subjects with mild to moderate knee OA and 65 healthy controls. Demographic data was collected from all participants at baseline. Serum levels of vitamin D as well as markers of oxidative stress including malondialdehyde (MDA), total oxidant status (TOS), superoxide dismutase (SOD), oxidative stress index (OSI), paraoxonase-1 (PON-1), glutathione peroxidase (GPX), catalase (CAT), and total antioxidant capacity (TAC) were evaluated for each participant. Furthermore, serum concentrations of MMP-1, MMP-3, MMP-13, and cartilage oligomeric matrix protein (COMP) were measured.

Results

The results of the present study indicated that individuals with vitamin D insufficiency had higher levels of MDA, TOS, SOD, and OSI as well as lower levels of PON-1 and TAC. Based on the linear regression analysis, serum vitamin D levels were inversely correlated with MDA, TOS, SOD, OSI, MMP-1, and MMP-13 and positively associated with TAC levels (p < 0.0001). Patients with sufficient vitamin D levels had lower MMP-1 and MMP-13 levels compared to patients with vitamin D insufficiency (p < 0.001 and p < 0.001, respectively).

Conclusion

Findings from this study showed a strong association between vitamin D deficiency and increased oxidative stress and MMPs activity in patients with knee OA.

Effects of Vitamin D on Cardiovascular Risk and Oxidative Stress

INTRODUCTION

Vitamin D has been primarily studied as an important factor influencing bone and calcium metabolism. Metabolites of vitamin D are essential for whole-body calcium homeostasis, maintaining serum calcium levels within a narrow range by regulating this process in the bones and gut. Nevertheless, its deficiency is also related to increased risk of type 2 diabetes mellitus (T2DM), metabolic syndrome (MS), and cardiovascular disease (CVD)-with increased visceral adipose tissue and body mass index (BMI), as well as the frequently associated hypercholesterolemia. It has been reported that vitamin D levels are inversely related to cardiovascular (CV) risk in men and women. However, the effects of vitamin D on distinct outcomes in women and the dose of supplementation needed to improve clinical endpoints have not been established. 25-Hydroxyvitamin D [25(OH)D] reduces systemic inflammatory mediators in CVD and favors the release of anti-inflammatory cytokines from the immune system. In addition, 25(OH)D can be primarily converted into calcitriol (1,25-dihydroxycholecalciferol [1,25(OH)2D]) in the kidneys through the action of the 1-α-hydroxylase enzyme. Calcitriol, through the downregulation mechanism of renin expression, renin-angiotensin-aldosterone system (RAAS) activity, and its interaction with the vitamin D receptor, can bring CV benefits. The calcitriol form also lowers parathyroid hormone (PTH) levels by indirectly causing a reduction in aldosterone and mineralocorticoid synthesis. Elevated plasma aldosterone is related to endothelial dysfunction and CVD in hypovitaminosis D status.

CONCLUSION

Vitamin D supplementation may benefit certain risk groups, as it improves metabolic variables, reducing oxidative stress and CV outcomes. More studies are needed to define interventions with vitamin D in men and women.

The associations of particulate matter short-term exposure and serum lipids are modified by vitamin D status: A panel study of young healthy adults

Particulate matter (PM) exposure is associated to the adverse change in blood lipids. Vitamin D is beneficial to lipid metabolism, but whether vitamin D levels modifies the impact of air pollutants on lipids is unclear. The purpose of the study was to investigate if vitamin D modifies the associations of PM and serum lipids in young healthy people. From December 2017 to January 2018, a panel study with five once weekly follow-ups was conducted on 88 healthy adults aged 21.09 (1.08) (mean (SD)) years on average in Guangzhou, China. We measured serum lipids, serum 25-hydroxyvitamin D (25(OH)D) concentrations (440 blood samples in total), mass concentrations of particulate matter with diameters ≤2.5 μm (PM_2.5), ≤1.0 μm (PM_1.0), and ≤0.5 μm (PM_0.5), and number concentrations of particulate matter with diameters ≤0.2 μm (PN_0.2) and ≤0.1 μm (PN_0.1) at each follow-up. Linear mixed-effect models were applied to assess the interaction of vitamin D and size-fractionated PM short-term exposure on four lipid metrics. We found the interactions between 25(OH)D and size-fractionated PM exposure on blood lipids in different lags (lag 3 days and 4 days). An interquartile range increase in PM_2.5, PM_1.0, PM_0.5 were significantly associated with increments of 12.30%, 12.99%, and 13.66% in triglycerides (TGs) at lag 4 days at vitamin D levels <15 ng/mL group, respectively. Similar results were found for PN_0.2, PN_0.1 and low-density lipoprotein cholesterol (LDL-C). All the associations between size-fractionated PM and blood lipids were found null statistically significant in vitamin D levels ≥15 ng/mL group.

25-hydroxyvitamin D3 inhibits oxidative stress and ferroptosis in retinal microvascular endothelial cells induced by high glucose through down-regulation of miR-93

BACKGROUND

The decrease of vitamin D plays a critical role in diabetes mellitus (DM)-induced oxidative stress and vascular endothelial injury. Therefore, we investigated the effect and mechanism of 25-hydroxyvitamin D3 (25 (OH) D3) on oxidative stress and ferroptosis induced by high glucose in human retinal microvascular endothelial cells (hRMVECs). And the objective of this paper was to propose a new strategy for the prevention and treatment of diabetic retinopathy (DR).

METHODS

First, hRMVECs were transfected with mimics NC or miR-93. After that, cells were treated with 100 nM / 500 nM 25 (OH) D3 and then cultured in a high glucose (30 mM) environment. Subsequently, qRT-PCR was employed to detect the expression level of miR-93; CCK-8 for the proliferation of cells in each group; biochemical tests for the level of intracellular reactive oxygen species (ROS), malondialdehyde (MDA), reduced glutathione (GSH) and ferrous ion (Fe²⁺); and Western blot for the expression of ferroptosis-related proteins glutathione peroxidase 4 (GPX4) and SLC7A11).

RESULTS

Under a high glucose environment, 25 (OH) D3 at 100 nM/500 nM could significantly promote the proliferation of hRMVECs, remarkably decrease the level of intracellular ROS/MDA, and up-regulate the level of GSH. Besides, 25 (OH) D3 greatly reduced Fe²⁺ level in the cells while increased protein level of GPX4 and SLC7A11. Subsequently, we found that high glucose induced miR-93 expression, while 25 (OH) D3 markedly decreased high glucose-induced miR-93 overexpression. Furthermore, overexpression of miR-93 inhibited the functions of 25 (OH) D3 by activating ROS (ROS and MDA were up-regulated while GSH was down-regulated) and inducing Fe²⁺ (Fe²⁺ level was up-regulated while GPX4 and SLC7A11 level was down-regulated) in cells.

CONCLUSION

25 (OH) D3 may inhibit oxidative stress and ferroptosis in hRMVECs induced by high glucose via down-regulation of miR-93.

Assessment of Vitamin D status and association with inflammation: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project

BACKGROUND

It is unclear whether 25(OH)D concentrations in children and female adults may be influenced by inflammation and thus require adjustment when estimating the population prevalence of vitamin D deficiency.

OBJECTIVES

We examined correlations between inflammation biomarkers, CRP or alpha-1-acid glycoprotein (AGP), and serum 25(OH)D concentrations among preschool children (PSC; 6-59 mo) and nonpregnant females of reproductive age (FRA; 15-49 y).

METHODS

We analyzed cross-sectional data from 6 nationally representative nutrition surveys (Afghanistan, Cambodia, Pakistan, UK, USA, and Vietnam) conducted among PSC (n = 9880) and FRA (n = 14,749) from the Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia project. Rank correlations between CRP or AGP and 25(OH)D concentrations were examined while taking into account complex survey design effects.

RESULTS

Among both PSC and FRA, correlations between inflammation and vitamin D biomarkers were weak and inconsistent across surveys. For PSC, correlation coefficients between CRP and 25(OH)D concentrations ranged from -0.04 to 0.08, and correlations between AGP and 25(OH)D ranged from 0.01 to 0.05. Correlation coefficients between CRP and 25(OH)D for FRA ranged from -0.11 to 0.14, and correlations between AGP and 25(OH)D concentrations ranged from -0.05 to 0.01.

CONCLUSIONS

Based on the weak and inconsistent correlations between CRP or AGP and 25(OH)D, there is no rationale to adjust for these inflammation biomarkers when estimating population prevalence of vitamin D deficiency in PSC or FRA.

Mechanisms of action of vitamin D in delaying aging and preventing disease by inhibiting oxidative stress

Although several recent studies have shown that vitamin D supplementation beneficially decreases oxidative stress parameters, there is no consensus on this subject in humans. Thus the role of vitamin D supplementation has recently become a controversial topic because large intervention studies in humans have not shown significant benefits. These studies have indicated that supplementation with precursor forms of active vitamin D has no effect on all-cause mortality, cannot reduce the fracture risk of the elderly, cannot reduce the incidence of cancer or cardiovascular disease in the elderly, and cannot significantly reduce the incidence risk of diabetes in the elderly. However, a link between several age-related diseases and enhanced oxidative stress has been found in mice with insufficient or deficient 1,25-dihydroxyvitamin D (1,25(OH)₂D), the active form of vitamin D, which indicates that reduced active vitamin D accelerates aging and age-related diseases by increasing oxidative stress. Furthermore, supplementation of exogenous 1,25(OH)₂D₃, or antioxidants, could dramatically postpone aging, prevent osteoporosis and spontaneous tumor development induced by 1,25(OH)₂D insufficiency or deficiency, by inhibiting oxidative stress. Mechanistically, the antioxidative effects of 1,25(OH)₂D₃ are carried out via the vitamin D receptor (VDR) by activation of the Nrf2 oxidative stress response pathway though transcriptional or posttranscriptional activation of Nrf2 or transcriptional upregulation of Sirt1 and Bmi1 expression. Whether discrepancies between studies in humans and in mice reflect the different forms of vitamin D examined remains to be determined.

Association between serum 25-hydroxyvitamin d and myeloperoxidase: A cross-sectional study of a general population in China

Background

Several studies have found a strong association between cardiovascular diseases and myeloperoxidase (MPO) as a marker of oxidative stress. Although the anti-inflammatory effects of vitamin D in adults have been validated, evidence about the relationship between MPO and 25(OH)D is lacking. This study aimed to investigate the relationship between MPO and 25(OH)D in the general Chinese population.

Methods

From November 2018 to August 2019, a total of 6414 subjects were enrolled in a tertiary referral hospital in China, which included 3,122 women and 3,292 men. The dependent and independent variables were MPO and 25(OH)D, respectively. The confounders included age, sex, body mass index, waist-hip ratio, smoking status, alcohol drinking status, calcium, and parathyroid hormone concentration.

Results

In the fully adjusted model, we found that MPO decreased by 0.12 (95% CI −0.16, −0.08), ng/mL for each unit (1 nmol/L) increase in 25(OH)D. When 25(OH) D was divided into quartiles, compared with Q1 (< 41.4 nmol/L), the adjusted beta coefficients (β) of MPO in Q2–Q4 were −2.29 (95% CI, −4.31 to −0.27), −4.76 (95% CI, −6.83 to −2.69), and −6.07 (95% CI, −8.23 to −3.92), respectively (P for the trend < 0.0001). When 25(OH) D was divided according to clinical severity, compared with the severely deficient (< 30 nmol/L) s≥ 30, < 50 nmol/L) and sufficient groups (≥ 50 nmol/L) were −2.59 (95% CI, −5.87 to 0.69) and −5.87 (95% CI, −9.17 to −2.57), respectively (P for the trend < 0.0001).

Conclusion

After adjusting for age, sex, BMI, waist-hip ratio, smoking status, alcohol status, calcium, and PTH, circulating 25(OH)D was negatively associated with MPO.

The vitamin D receptor gene variants, ApaI, TaqI, BsmI, and FokI in diabetic foot ulcer and their association with oxidative stress

INTRODUCTION

To date, numerous disorders have been linked to vitamin D deficiency. Several lines of evidence indicate a relationship between vitamin D deficiency and the risk of developing type 2 diabetes. It has been postulated that vitamin D may influence insulin activity, which can predispose individuals to develop type 2 diabetes.

MATERIALS AND METHODS

In this case-control study, 262 patients with definite type 2 diabetes were enrolled, considering whether they were being affected by diabetic foot ulcers or not. The plasma levels of vitamin D and homocysteine were measured using ELISA, and the PCR-RFLP technique was utilized to determine allele and genotype frequencies. The antioxidant capacity of plasma samples of diabetic patients was analyzed using the thiobarbituric acid reactive substance (TBARS) and ferric reducing ability of plasma (FRAP) assays.

RESULTS

The obtained results demonstrated no significant difference in the frequency of TaqI and BsmI polymorphisms between the case and control groups. However, the frequency of genotypes and alleles of the ApaI polymorphism in the VDR gene significantly differed between the case and control groups. A significant correlation was found between ApaI polymorphism and oxidative stress, as patients with the GG genotype had lower levels of TBARS than those with other genotypes. Furthermore, in the case group, patients with the CC genotype of BsmI showed a significant decrease in TBARS levels.

DISCUSSION

It seems that the plasma levels of vitamin D do not differ between patients with or without diabetic foot ulcers; however, the presence of some VDR gene polymorphisms is thought to be involved in the development of diabetic foot ulcers via increasing oxidative stress.

Exercise Outcomes in Childhood Obesity-Related Inflammation and Oxidative Status

Childhood obesity is identified as one of the major public health issues to increase the risk for cardiometabolic diseases and related complications in adulthood. The literature has supported inflammation and oxidative stress as the primary underlying mechanisms involved in the pathogenesis of obesity-related diseases. Epidemiological evidence consistently shows the benefits of physical activity in the improvement of obesity-mediated inflammation and oxidative stress status. In this narrative mini-review, the available scientific evidence on the potential effects of exercise in alleviating these susceptibilities in childhood obesity will be assessed.

Systemic Inflammation, Oxidative Stress and Cardiovascular Health in Children and Adolescents: A Systematic Review

Recent studies indicate that cerebrovascular diseases and processes of atherosclerosis originate in the childhood era and are largely influenced by chronic inflammation. Some features of vascular dysfunction in adulthood may even be programmed prenatally via genetic influences and an unfavorable intrauterine milieu. Oxidative stress, defined by an imbalance between the production and generation of reactive oxygen species (ROS) in cells and tissues and the capability of an organism to scavenge these molecules via antioxidant mechanisms, has been linked to adverse cardiovascular health in adults, yet has not been systematically reviewed in the pediatric population. We performed a systematic search as per the PRISMA guidelines in PubMed/Medline and Cochrane Reviews and detected, in total, 1228 potentially eligible pediatric articles on systemic inflammation, oxidative stress, antioxidant use, cardiovascular disease and endothelial dysfunction. The abstracts and full-text manuscripts of these were screened for inclusion and exclusion criteria, and a total of 160 articles were included. The results indicate that systemic inflammation and oxidative stress influence cardiovascular health in many chronic pediatric conditions, including hypertension, obesity, diabetes mellitus types 1 and 2, chronic kidney disease, hyperlipidemia and obstructive sleep apnea. Exercise and diet may diminish ROS formation and enhance the total serum antioxidant capacity. Antioxidant supplementation may, in selected conditions, contribute to the diminution of the oxidative state and improve endothelial function; yet, in many areas, studies provide unsatisfactory results.

Protective actions of vitamin D, anandamide and melatonin during vascular inflammation: Epigenetic mechanisms involved

Vascular inflammation is one of the main activating stimuli of cardiovascular disease and its uncontrolled development may worsen the progression and prognosis of these pathologies. Therefore, the search for new therapeutic options to treat this condition is undoubtedly needed. In this regard, it may be better to repurpose endogenous anti-inflammatory compounds already known, in addition to synthesizing new compounds for therapeutic purposes. It is well known that vitamin D, anandamide, and melatonin are promising endogenous substances with powerful and wide-spread anti-inflammatory properties. Currently, the epigenetic mechanisms underlying these effects are often unknown. This review summarizes the potential epigenetic mechanisms by which vitamin D, anandamide, and melatonin attenuate vascular inflammation. This information could contribute to the improvement in the therapeutic management of multiple pathologies associated with blood vessel inflammation, through the pharmacological manipulation of new target sites that until now have not been addressed.

[Oxidative stress in schizophrenia as a promising target for psychopharmacotherapy]

Until now, only dopamine receptor blockers are used for psychopharmacotherapy of schizophrenia, despite the active search for alternative pharmacological agents and a lot of research. However, most of these studies concerned molecules that somehow affect various neurotransmitter receptors. In addition, various anti-inflammatory drugs have been studied quite actively. At the same time, attempts to correct oxidative stress are given significantly less attention, although the emergence of the latter is facilitated by completely different pathophysiological processes and environmental factors associated with the development of schizophrenia. NMDA receptor blockage, vitamin D deficiency, social isolation, chronic stress in adolescence, inflammation, perinatal infection etc. - all this can ultimately lead to the occurrence of oxidative stress. However, there is a significant difference in the severity of this process depending on the stage of the course of schizophrenia, which probably partially explains the heterogeneity of results of the studies on the oxidative stress biomarkers in this disorder. In order to overcome these methodological problems, it seems promising to conduct double-blind studies of the effectiveness of antioxidants in schizophrenia with the selection of groups of patients taking into account the stage of the disorder and the level of certain biomarkers of oxidative stress (F2-isoprostanes, 8-oxodG, 8-oxoGuo). The optimal pharmacological agents for such studies are N-acetylcysteine due to the positive results of previous studies, and melatonin as an antioxidant with a unique activity profile.

Vitamin D status and systemic redox biomarkers in adults with obesity

BACKGROUND & AIMS

Vitamin D has been proposed to have a protective role against oxidative stress. The present study was conducted to test the hypothesis that suboptimal levels of 25(OH)D are related to oxidative/antioxidative biomarkers in adults independently of obesity.

METHODS

In this case-control study, 140 subjects with obesity and 90 age- and sex-matched 25(OH)D sufficient normal weight controls were selected. Subjects with obesity were categorized as 25(OH)D sufficient, insufficient, and deficient based on their serum 25(OH)D concentrations. Serum malondialdehyde (MDA), total oxidant status (TOS), and total antioxidant capacity (TAC) as well as erythrocytes superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) along with serum paraoxonase-1 (PON1) and arylesterase (AREase) activities were assessed.

RESULTS

Serum concentrations of 25(OH)D were inversely correlated with BMI, WC, fat mass, and visceral fat. Serum levels of MDA and TOS, and erythrocyte SOD activities were significantly higher, whereas, serum TAC, PON1, and AREase were significantly lower in subjects with obesity compared to the controls (p < 0.0001). 25(OH)D deficient obese subjects exhibited higher serum levels of MDA as well as erythrocyte SOD activity (p < 0.05) and lower serum levels of TAC (p < 0.0001), PON1 (p < 0.05), and AREase (p < 0.0001) compared to obese subjects with 25(OH)D sufficiency and controls even when adjusted for BMI.

CONCLUSIONS

The present findings demonstrated a strong association between the severity of 25(OH)D deficiency and oxidative/antioxidative related parameters independently of obesity.

Relationship between 25 Hydroxyvitamin D, Overweight/Obesity Status, Pro-Inflammatory and Oxidative Stress Markers in Patients with Type 2 Diabetes: A Simplified Empirical Path Model

Vitamin D deficiency is highly prevalent in patients with overweight/obesity and type 2 diabetes (T2DM). Herein, we investigated the relationship between vitamin D status and overweight/obesity status, insulin resistance (IR), systemic inflammation as well as oxidative stress (OS). Anthropometric and laboratory assessments of 25-hydroxyvitamin D (25(OH)D) and glycemic, pro-inflammatory and OS biomarkers were performed in a sample of 47 patients with T2DM who were divided into categories based on overweight and degree of obesity. The main findings were: the overweight/obesity status correlated negatively with the degree of serum 25(OH)D deficiency (ρ = −0.27) with a trend towards statistical significance (p = 0.069); the homeostasis model assessment of insulin resistance (HOMA-IR) was significantly different (p = 0.024) in patients with 25(OH)D deficiency, as was total oxidant status (TOS) and oxidative stress index (OSI) in patients with severe serum 25(OH)D deficiency as compared to those with 25(OH)D over 20 ng/mL (TOS: p = 0.007, OSI: p = 0.008); and 25(OH)D had a negative indirect effect on TOS by body mass index (BMI), but BMI was not a significant mediator of the studied relationship. In a setting of overweight and increasing degree of obesity, patients with T2DM did not display decreasing values of 25(OH)D. Subjects with the lowest values of 25(OH)D presented the highest values of BMI. Patients with 25(OH)D deficiency were more insulin resistant and showed increased OS but no elevated systemic inflammation. The negative effect of 25(OH)D on TOS did not seem to involve BMI as a mediator.

Relationship between BsmI polymorphism and VDR gene methylation profile, gender, metabolic profile, oxidative stress, and inflammation in adolescents

BACKGROUND

the biological activity of vitamin D depends on the activity of its receptor or VDR. On the other hand, the activity of this receptor is influenced by its state of methylation. The objective of this study was to verify if the BsmI polymorphism of the VDR gene influences its methylation profile in adolescents. Secondly, it was to verify if the status of some metabolic factors (oxidative stress, inflammation, lipid profile, and glycemia) in the serum, and gender-adjusted vitamin D levels are independent factors with an influence on the VDR methylation profile.

METHODS AND RESULTS

the study included 198 adolescents of both sexes, aged 15-19 years, who underwent testing for VDR gene methylation polymorphisms, serum vitamin D levels, and metabolic, oxidative stress, and systemic inflammation markers. It was observed that the BB genotype was less methylated than the other groups (26.1 % versus 30.3 %, and 29.3 % for Bb and bb, respectively), although without statistical differences between them. The odds ratio indicated a protection of 13 % (partially methylated) for vitamin D status, while alpha glycols increased the risk ratio (of being partially methylated) by 3 %. MDA was protective at a 28 % chance of risk that adolescents with higher levels of lipid peroxidation would be hypomethylated.

CONCLUSION

we conclude that the methylation profile of the VDR gene is not influenced by the different BsmI polymorphism genotypes, and that serum vitamin D and serum markers of oxidative stress and inflammation can modulate this profile.

Obesity-related asthma in children: A role for vitamin D

Excess adipose tissue predisposes to an enhanced inflammatory state and can contribute to the pathogenesis and severity of asthma. Vitamin D has anti-inflammatory properties and low-serum levels are seen in children with asthma and in children with obesity. Here we review the intersection of asthma, obesity, and hypovitaminosis D in children. Supplementation with vitamin D has been proposed as a simple, safe, and inexpensive adjunctive therapy in a number of disease states. However, little research has examined the pharmacokinetics of vitamin D and its therapeutic potential in children who suffer from obesity-related asthma.

Vitamin D receptor gene ApaI and FokI polymorphisms and its association with inflammation and oxidative stress in vitamin D sufficient Caucasian Spanish children

BACKGROUND

Vitamin D has gone from being just one vitamin to being an important prohormone with multiple effects on different tissue types. The mechanism of action of the active form or calcitriol is mediated by the intracellular vitamin D receptor (VDR). The interaction of the VDR with calcitriol modulates the expression of target genes involved in cell proliferation and cytokine production. Several studies have explored the effects of vitamin D deficiency in inflammatory disorders. Furthermore, some mutations in the VDR can affect its functionality. The focus of this study was to explore associations between VDR single nucleotide polymorphisms (SNPs) and markers of inflammation and oxidative stress in vitamin D sufficient children.

METHODS

This is a cross-sectional study of a Caucasian Spanish population including 155 healthy children (87 males, 68 females) aged 10 to 14 years. FokI, ApaI and TaqI SNPs of the VDR gene were genotyped. Routine biochemistry, serum levels of interleukin-6, tumor necrosis factor-α, interferon-γ, 8-isoprostaglandin F2α and nitrates were determined.

RESULTS

The homozygous major allele AA in the FokI SNP was associated with increased levels of high-density lipoprotein cholesterol in a recessive inheritance mode (P=0.025). The minor allele A of ApaI was significantly associated with decreased serum tumor necrosis factor-α and 8-isoprostaglandin F2α in an additive mode (P=0.016 and P=0.020 respectively). No significant associations were observed between the TaqI SNP and any of the parameters evaluated. Haplotype analysis confirmed the significance of the relationships between ApaI and FokI SNPs and parameters associated with inflammation and oxidative stress.

CONCLUSIONS

Genetic variations of VDR are associated with subtle changes in metabolic, inflammatory and oxidative stress markers. These results may provide a better understanding of the relationships between vitamin D and these clinical parameters.

The potential link between inherited G6PD deficiency, oxidative stress, and vitamin D deficiency and the racial inequities in mortality associated with COVID-19

There is a marked variation in mortality risk associated with COVID-19 infection in the general population. Low socioeconomic status and other social determinants have been discussed as possible causes for the higher burden in African American communities compared with white communities. Beyond the social determinants, the biochemical mechanism that predisposes individual subjects or communities to the development of excess and serious complications associated with COVID-19 infection is not clear. Virus infection triggers massive ROS production and oxidative damage. Glutathione (GSH) is essential and protects the body from the harmful effects of oxidative damage from excess reactive oxygen radicals. GSH is also required to maintain the VD-metabolism genes and circulating levels of 25-hydroxyvitamin D (25(OH)VD). Glucose-6-phosphate dehydrogenase (G6PD) is necessary to prevent the exhaustion and depletion of cellular GSH. X-linked genetic G6PD deficiency is common in the AA population and predominantly in males. Acquired deficiency of G6PD has been widely reported in subjects with conditions of obesity and diabetes. This suggests that individuals with G6PD deficiency are vulnerable to excess oxidative stress and at a higher risk for inadequacy or deficiency of 25(OH)VD, leaving the body unable to protect its 'oxidative immune-metabolic' physiological functions from the insults of COVID-19. An association between subclinical interstitial lung disease with 25(OH)VD deficiencies and GSH deficiencies has been previously reported. We hypothesize that the overproduction of ROS and excess oxidative damage is responsible for the impaired immunity, secretion of the cytokine storm, and onset of pulmonary dysfunction in response to the COVID-19 infection. The co-optimization of impaired glutathione redox status and excess 25(OH)VD deficiencies has the potential to reduce oxidative stress, boost immunity, and reduce the adverse clinical effects of COVID-19 infection in the AA population.

The Relationship of Vitamin D Status, Adherence to the Mediterranean Diet, and Physical Activity in Obese Children and Adolescents

Vitamin D deficiency is associated with a range of chronic diseases, including childhood obesity. Prevalence of vitamin D deficiency in obese children and adolescents ranges from 6.5% to 57%. This cross-sectional study included 92 obese patients with body mass index z-score >2 and 39 subjects in the control group. Anthropometric and laboratory patient assessment were performed, including the fasting 25-hydroxyvitamin D (25(OH)D). Adherence to the Mediterranean diet was assessed by Mediterranean Diet Quality Index for children and adolescents (KIDMED index), while physical activity was evaluated by Physical Activity Questionnaire (PAQ). Serum levels of 25(OH)D were significantly lower in obese subjects compared to the control group (52.0 ± 17.93 vs. 64.09 ± 25.82 nmol/L, P = .003). The subgroup of obese patients with metabolic syndrome (MS) had significantly lower levels of serum vitamin D when compared to the subgroup of obese patients without MS and the control group (46.99 ± 17.11 vs. 54.58 ± 17.93 vs. 64.09 ± 25.82 nmol/L, P = .003). Obese patients with MS had lower PAQ score when compared to obese without MS and the control group (2.32 ± 0.55 vs. 2.49 ± 0.67 vs. 2.85 ± 0.63 nmol/L, P = .002), while no significant differences were observed in the KIDMED index (4.23 ± 1.81 vs. 4.21 ± 2.13 vs. 4.87 ± 2.29, P = .251), respectively. PAQ score was in positive correlation with serum levels of 25(OH)D (r = 0.305, P < .001). This study demonstrated that obese children and adolescents have significantly lower values of serum 25(OH)D. The positive correlation between vitamin D and PAQ score points to the importance of physical activity in the prevention of further cardiovascular complications and MS.

Relationship of oxidative stress to visceral adiposity in youth and role played by vitamin D

BACKGROUND

Visceral adipose tissue (VAT) accumulation is a major cardiometabolic risk factor, associated with increased inflammation. Oxidative stress (OS) is also associated with inflammation and cardiometabolic issues, yet mainly through general obesity. Both OS and obesity were linked to vitamin D deficiency.

OBJECTIVES

To investigate whether OS increase is associated with VAT accumulation in youth, and whether in the presence of VAT accumulation, a higher vitamin D status is associated with lower OS.

METHODS

One hundred and fifty-eight youth with overweight/obesity, 7 to 17 years old, were recruited (Pediatric Clinic, Luxembourg). We assessed visceral and subcutaneous abdominal adipose tissues by magnetic resonance imaging, OS by DNA/RNA oxidative damage with ELISA and vitamin D by high-performance liquid chromatography.

RESULTS

VAT was the body fat compartment the most strongly associated with OS (R_Pearson : 0.298; P < 10^-4 ). The general linear (GLM) models assessing the relationship between OS, VAT and vitamin D concentrations showed that "Log₁₀ OS = (0.003 × VAT) + 3.911 (R²_adjusted : 0.083; P-value < 10^-4 )"; "Log₁₀ OS = (0.003 × VAT) - (0.156 × log₁₀ vitamin D) + 4.110 (R²_adjusted : 0.101; P-value < 10^-4 )". After back-transformation of the log-values into normal values, the GLM showed that, for a person with an average value of VAT (40.7 cm² ), a 10 cm² increase in VAT would increase OS by approx. 771.833 pg/mL, after age, gender, Tanner stage and physical activity adjustment. An approximate increase of 9 ng/mL of vitamin D would counterbalance this negative effect of increased VAT.

CONCLUSION

Dietary strategies improving vitamin D status should be investigated to tackle VAT and OS increase.

Influence of the Mediterranean Diet on 25- Hydroxyvitamin D Levels in Adults

The Mediterranean diet (MD) is a dietary pattern effective in terms of prevention of obesity-related diseases, and represents the gold standard in preventive medicine, due to the synergistic action of many nutrients with antioxidant and anti-inflammatory properties. In addition, excess body weight significantly increases the risk of hypovitaminosis D, a well-recognized common feature of individuals with obesity. It is well-known that there is a clear gender difference in the adherence to the MD. The aim of this study was to investigate the association between adherence to the MD and 25-hydroxyvitamin D (25OHD) levels in adults, according to gender. Study population consisted of 617 participants; 296 were males and 321 were females, matched by age and body mass index (BMI). A validated 14-item questionnaire PREDIMED (Prevención con dieta Mediterránea) was used for the assessment of adherence to the MD. The 25OHD levels were determined by a direct competitive chemiluminescence immunoassay. Females have a higher PREDIMED score than males (7.4 ± 2.8 vs. 6.7 ± 3.1 score, p = 0.001), and according to PREDIMED categories, a greater percentage of males had low adherence to the MD compared to their female counterparts (40.2% vs. 37.1%; χ² = 8.94, p = 0.003). The 25OHD levels were higher in males than in females (18.3 ± 7.3 vs. 16.8 ± 7.8 ng/mL, p = 0.01), and a higher percentage of males had sufficient 25OHD levels (>30 ng/mL) than their female counterparts (10.5% vs. 3.4%, χ² = 10.96, p < 0.001). Stratifying the sample population according to 25OHD categories, BMI decreased and PREDIMED score increased significantly along with the increased 25OHD levels, in both males and females, respectively (p < 0.001). Looking at the bivariate correlations, PREDIMED score was positively correlated with 25OHD levels after adjusting for age and BMI, in both males (r = 0.21, p < 0.001) and females (r = 0.30, p < 0.001). At the bivariate proportional odds ratio (OR) model, 25OHD levels presented the highest OR values in the category low adherence vs. high adherence to the MD, in both genders (OR 1.21 and OR 1.31, in males and females, respectively). Receiver operator characteristic (ROC) analysis was performed to determine the cut-off values of PREDIMED scores predictive of 25OHD levels: PREDIMED score >5 in males (p < 0.001) and >7 in females (p < 0.001) could serve as thresholds for 25OHD levels above the median. The results of our study highlighted a novel positive association between adherence to the MD and 25OHD levels in both genders. Although 25OHD levels were higher in males than females, 69.7% were deficient. To the best of our knowledge, this is the first study to show that high adherence to the MD is associated with low BMI and high 25OHD levels in both genders, probably through the anti-inflammatory and anti-oxidant effects that are synergistically exerted by either MD or vitamin D on body weight.

Vitamin D and Endothelial Function

Vitamin D is known to elicit a vasoprotective effect, while vitamin D deficiency is a risk factor for endothelial dysfunction (ED). ED is characterized by reduced bioavailability of a potent endothelium-dependent vasodilator, nitric oxide (NO), and is an early event in the development of atherosclerosis. In endothelial cells, vitamin D regulates NO synthesis by mediating the activity of the endothelial NO synthase (eNOS). Under pathogenic conditions, the oxidative stress caused by excessive production of reactive oxygen species (ROS) facilitates NO degradation and suppresses NO synthesis, consequently reducing NO bioavailability. Vitamin D, however, counteracts the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase which produces ROS, and improves antioxidant capacity by enhancing the activity of antioxidative enzymes such as superoxide dismutase. In addition to ROS, proinflammatory mediators such as TNF-α and IL-6 are risk factors for ED, restraining NO and eNOS bioactivity and upregulating the expression of various atherosclerotic factors through the NF-κB pathway. These proinflammatory activities are inhibited by vitamin D by suppressing NF-κB signaling and production of proinflammatory cytokines. In this review, we discuss the diverse activities of vitamin D in regulating NO bioavailability and endothelial function.

The Impact of Obesity on the Association between Vitamin D Deficiency and Cardiovascular Disease

The aim of this article is to review the literature regarding the relationship between vitamin D deficiency and cardiovascular disease (CVD) and its modification in the presence of obesity. Despite the strong association between vitamin D status and cardiovascular outcomes, vitamin D supplementation trials in the general population have failed to decrease the incidence of cardiovascular events and mortality. A comprehensive study of the published literature and a comparison with experimental data lead to the conclusion that obesity, due to its high prevalence and strong association with both vitamin D deficiency and CVD, may act as a critical confounder, which is responsible for the different results on this association. Adoption of a vitamin D preventive supplementation strategy for CVD is unlikely to yield any benefit to the general population. However, it might be particularly useful in obese adults with increased risk for CVD.

Free Vitamin D: Relationship to Insulin Sensitivity and Vascular Health in Youth

OBJECTIVE

To evaluate the relationship of free 25 hydroxy vitamin D [free 25(OH)D] or bioavailable vitamin D (BioD) concentrations to insulin sensitivity and cardiovascular disease risk markers in normal weight and overweight youth.

STUDY DESIGN

Cross-sectional study of 79 adolescents 15.4 ± 0.2 years, 18 normal weight, 30 overweight, and 31 overweight with prediabetes who underwent peripheral arterial tonometry, dual-energy x-ray absorptiometry, and hyperinsulinemic-euglycemic clamp in subset (n = 71) for determination of reactive hyperemia index (RHI), body composition, and insulin sensitivity. 25(OH)D and vitamin D binding protein were measured; free 25(OH)D and BioD were calculated.

RESULTS

Across tertiles of free 25(OH)D concentrations (4.0 ± 0.2, 7.5 ± 0.3, and 17.0 ± 2.1 pg/mL, P < .001), the group in the lowest tertile had significantly higher percent body fat (37.8 ± 1.1, 35.2 ± 1.5 and 25.3 ± 2.1%, P < .001), lower insulin sensitivity (4.4 ± 0.4, 6.7 ± 1.2, and 8.2 ± 0.9 mg/kg fat-free mass/minute per μu/mL, P = .03), lower RHI (1.42 ± 0.06, 1.54 ± 0.06, and 1.77 ± 0.09, P = .002), higher high-sensitivity C-reactive protein (3.4 ± 0.6, 1.7 ± 0.3, and 1.6 ± 0.4 mg/L, P = .015) compared with the second and third tertiles, respectively. Free 25(OH)D levels were inversely related to percent body fat and high-sensitivity C-reactive protein, and positively related to RHI and insulin sensitivity. The relationships of free 25(OH)D to RHI and to insulin sensitivity were no longer significant after adjusting for %body fat. Similar relationships were observed for BioD.

CONCLUSIONS

Youth with low free 25(OH)D or BioD concentrations have lower insulin sensitivity and worse endothelial function and inflammatory biomarkers compared with those with more sufficient 25(OH)D. However, the effects of vitamin D on these biomarkers may not be independent of the effect of adiposity.

Dynamic thiol/disulfide homeostasis and oxidant status in patients with hypoparathyroidism

Background

In this study, we aimed at determining the dynamic thiol/disulfide homeostasis and oxidant balance, and investigating the relation of these parameters to the severity of the disease and the serum calcium levels.

Methods

55 patients with iatrogenic hypoparathyroidism follow-ups and 40 healthy volunteers were included in the study. The blood dynamic thiol/sulfide balance, Total Antioxidant Status (TAS), Total Oxidant Status (TOS), Paraoxonase Enzyme Activity (PON) levels were measured in serum samples.

Results

In our study, it was found that the disulfide, disulfide/native thiol, disulfide/total thiol levels were higher in the hypoparathyroidism group. A negative correlation was found between 25-hydroxy vitamin D (25-OH vitamin D) and disulfide, disulfide/native thiol and disulfide/total thiol, and a positive correlation was found between native thiol and total thiol ratio; and the corrected calcium levels and PON levels were negatively correlated.

Conclusions

Consequently, a change in favour of disulfide was found in the dynamic thiol-disulfide homeostasis in the hypoparathyroidism group in our study.

The relationship between serum vitamin D levels and intima-media thickness in term infants

Increasing epidemiologic evidence indicates that vitamin D deficiency is linked to a series of diseases, including cardiovascular disease. This prospective study was designed to determine the relationship between 25 hydroxyvitamin D (25(OH)D) level and aortic intima-media thickness (aIMT) and carotid intima-media thickness (cIMT) in term healthy neonates. A total of 135 term, healthy infants were included in the study. Ultrasonographic measurements were performed at 24-48 h after birth. Blood samples were obtained from the umbilical cord at birth. The neonates were divided into four groups according to serum 25(OH)D vitamin levels. For the entire cohort, the mean 25 hydroxyvitamin D level was found to be 15.17 ± 9.66 ng/mL. The mean values of cIMT and aIMT measurements were 0.386 ± 0.052 and 0.412 ± 0.076 mm, respectively. In group 4, mean and maximum aIMT measurements were significantly lower than the other groups (p = <0.001 and 0.001, respectively). We did not observe any significant difference between groups regarding cIMT measurements. Correlation was found between aIMT and 25 hydroxyvitamin D levels (r = 0.295 p = < 0.001).Conclusion: We conclude that vitamin D deficiency may be associated with early relative intima-media thickening of the aorta already in the first week of life. What is Known: • Vitamin D deficiency is linked to a series of diseases, including cardiovascular disease. • Studies in adults and high-risk children have shown that the measurement of the intima-media thickness represents an excellent marker of subclinical atherosclerosis. What is New: • This is the first study evaluating the relationship between 25(OH)D vitamin level and intima-media thickness in term healthy neonates. • Vitamin D deficiency in neonates may induce atherosclerosis early in life and the aortic intima-media thickness measurements may be used as an early marker for detection.

Exploring possible relationships between 25(OH)D deficiency and variables related to inflammation, endothelial function, and enzymatic antioxidants in adolescent athletes: a prospective study

Although the role of vitamin D in calcium and bone metabolism is well documented, there is little clarity regarding the implications of low vitamin D status for inflammation, endothelial function, and antioxidant status in adolescent athletes. A prospective cohort study was conducted, and 44 male adolescent athletes, training at a sports academy in the Middle East, were assigned to either the intervention group (VitDs), consisting of vitamin D deficient athletes [twenty-five hydroxyvitamin D (25(OH)D) <20 ng/ml; n = 22], or the comparison group, consisting of vitamin D sufficient athletes [25(OH)D >30 ng/ml; n = 22]. Vitamin D status, inflammatory cytokines, endothelium-related variables, and antioxidant enzymes were measured twice during a nine-week training period. At the baseline, the athletes in the VitDs group had significantly lower concentrations of 25(OH)D, vascular endothelial growth factor (VEGF), and glutathione peroxidase (GPx), and higher levels of parathyroid hormone (PTH), interleukin-6 (IL-6), interleukin-1 receptor antagonist (IL-1ra), and nitrite (NO2) (p < 0.05), in comparison to the athletes in the sufficient group. After vitamin D supplementation for the VitDs group, the two cohorts differed considerably in vitamin D binding protein (VDBP) and PTH concentrations (p < 0.05). Our data suggest that the low levels of vitamin D possibly induced alterations in the investigated biochemical parameters of athletes in the VitDs group at the beginning of the monitoring period. Furthermore, while the vitamin D supplementation was effective in increasing 25(OH)D status, it may have concurrently positively influenced variables that are related to inflammation, endothelial function, and enzymatic antioxidants.

Vitamin D Deficiency: Effects on Oxidative Stress, Epigenetics, Gene Regulation, and Aging

Recent advances in vitamin D research indicate that this vitamin, a secosteroid hormone, has beneficial effects on several body systems other than the musculoskeletal system. Both 25 dihydroxy vitamin D [25(OH)₂D] and its active hormonal form, 1,25-dihydroxyvitamin D [1,25(OH)₂D] are essential for human physiological functions, including damping down inflammation and the excessive intracellular oxidative stresses. Vitamin D is one of the key controllers of systemic inflammation, oxidative stress and mitochondrial respiratory function, and thus, the aging process in humans. In turn, molecular and cellular actions form 1,25(OH)₂D slow down oxidative stress, cell and tissue damage, and the aging process. On the other hand, hypovitaminosis D impairs mitochondrial functions, and enhances oxidative stress and systemic inflammation. The interaction of 1,25(OH)₂D with its intracellular receptors modulates vitamin D–dependent gene transcription and activation of vitamin D-responsive elements, which triggers multiple second messenger systems. Thus, it is not surprising that hypovitaminosis D increases the incidence and severity of several age-related common diseases, such as metabolic disorders that are linked to oxidative stress. These include obesity, insulin resistance, type 2 diabetes, hypertension, pregnancy complications, memory disorders, osteoporosis, autoimmune diseases, certain cancers, and systemic inflammatory diseases. Vitamin D adequacy leads to less oxidative stress and improves mitochondrial and endocrine functions, reducing the risks of disorders, such as autoimmunity, infections, metabolic derangements, and impairment of DNA repair; all of this aids a healthy, graceful aging process. Vitamin D is also a potent anti-oxidant that facilitates balanced mitochondrial activities, preventing oxidative stress-related protein oxidation, lipid peroxidation, and DNA damage. New understandings of vitamin D-related advances in metabolomics, transcriptomics, epigenetics, in relation to its ability to control oxidative stress in conjunction with micronutrients, vitamins, and antioxidants, following normalization of serum 25(OH)D and tissue 1,25(OH)₂D concentrations, likely to promise cost-effective better clinical outcomes in humans.

Beneficial Effects of Vitamins K and D3 on Redox Balance of Human Osteoblasts Cultured with Hydroxyapatite-Based Biomaterials

Hydroxyapatite-based biomaterials are commonly used in surgery to repair bone damage. However, the introduction of biomaterials into the body can cause metabolic alterations, including redox imbalance. Because vitamins D3 and K (K1, MK-4, MK-7) have pronounced osteoinductive, anti-inflammatory, and antioxidant properties, it is suggested that they may reduce the adverse effects of biomaterials. The aim of this study was to investigate the effects of vitamins D3 and K, used alone and in combination, on the redox metabolism of human osteoblasts (hFOB 1.19 cell line) cultured in the presence of hydroxyapatite-based biomaterials (Maxgraft, Cerabone, Apatos, and Gen-Os). Culturing of the osteoblasts in the presence of hydroxyapatite-based biomaterials resulted in oxidative stress manifested by increased production of reactive oxygen species and decrease of glutathione level and glutathione peroxidase activity. Such redox imbalance leads to lipid peroxidation manifested by an increase of 4-hydroxynonenal level, which is known to influence the growth of bone cells. Vitamins D3 and K were shown to help maintain redox balance and prevent lipid peroxidation in osteoblasts cultured with hydroxyapatite-based biomaterials. The strongest effect was observed for the combination of vitamin D3 and MK-7. Moreover, vitamins promoted growth of the osteoblasts, manifested by increased DNA biosynthesis. Therefore, it is suggested that the use of vitamins D3 and K may protect redox balance and support the growth of osteoblasts affected by hydroxyapatite-based biomaterials.

Vitamin D status, oxidative stress, and inflammation in children and adolescents: A systematic review

Vitamin D deficiency is considered a global public health problem with high prevalence in children and adolescents. The majority of the studies in the literature have identified a relationship between vitamin D insufficiency/deficiency and obesity, as well as other traditional cardiometabolic risk factors in children and adolescents. Scarce studies address vitamin D status with oxidative stress and inflammation in the young population. The aim of this systematic review was to evaluate the evidence of the association of vitamin D status with oxidative stress and inflammation in children and adolescents. This is a systematic review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes (PRISMA) guideline on reporting systematic reviews. Eight studies were selected for this review. All included studies evaluated inflammatory biomarkers and two out of eight evaluated biomarkers of oxidative stress. The majority of the studies (five out of eight) found association of vitamin D status with biomarkers of oxidative stress and inflammation such as C-reactive protein (CRP), interleukin-6 (IL-6), cathepsin S, vascular cell adhesion molecule-1 (VCAM-1), malondialdehyde (MDA), myeloperoxidase, 3-nitrotyrosine, and superoxide dismutase (SOD). Vitamin D status is associated with oxidative stress and inflammation in the majority of the studies with children and adolescents. Thus, the assessment of vitamin D status is important because it is associated with nontraditional cardiometabolic markers in the pediatric population (review registration: PROSPERO CRD42018109307).

Cholecalciferol in ethanol-preferring rats muscle fibers increases the number and area of type II fibers

The chronic use of ethanol causes neuropathy and atrophy of type II fibers and promotes vitamin D decrease. This study evaluated cholecalciferol effects on the deep fibular nerve and extensor digitorum longus (EDL) muscle using an UChB ethanol-preferring rats model. Blood analyses were carried out to measure levels of 25-hydroxycholecalciferol (25(OH)D), calcium (Ca²⁺), Phosphorus (P), and parathyroid hormone (PTH). It was used EDL muscle to evaluate oxidative stress. The deep fibular nerve and EDL muscle were used for morphologic and morphometric assessment. 25(OH)D plasma levels were higher in the supplemented group and no alterations were observed in other parameters including the oxidative stress evaluation. The G ratio remained constant which indicates nervous conduction normality. Cholecalciferol supplementation promoted an increase in the number and area of type II fibers and a decrease in the area of type I fibers. In the studied model, there was neither alcoholic myopathy nor neuropathy. The EDL muscle glycolytic patterns in the high-drinker UChB rats may be associated with the differential effects of cholecalciferol on metabolism and protein synthesis in skeletal muscle.

Oxidative-Nitrative Stress and Poly (ADP-Ribose) Polymerase Activation 3 Years after Pregnancy

Background

Oxidative-nitrative stress and poly (ADP-ribose) polymerase activation have been previously observed in healthy and gestational diabetic pregnancies, and they were also linked to the development of metabolic diseases. The aim of the present study was to examine these parameters and their correlation to known metabolic risk factors following healthy and gestational diabetic pregnancies.

Methods

Fasting and 2 h postload plasma total peroxide level, protein tyrosine nitration, and poly (ADP-ribose) polymerase activation were measured in circulating leukocytes three years after delivery in women following healthy, "mild" (diet-treated) or "severe" (insulin-treated) gestational diabetic pregnancy during a standard 75 g OGTT. Nulliparous women and men served as control groups.

Results

Fasting plasma total peroxide level was significantly elevated in women with previous pregnancy (B = 0.52 ± 0.13; p < 0.001), with further increase in women with insulin-treated gestational diabetes (B = 0.36 ± 0.17; p < 0.05) (R² = 0.419). Its level was independently related to previous pregnancy (B = 0.47 ± 0.14; p < 0.01) and current CRP levels (B = 0.06 ± 0.02; p < 0.05) (R² = 0.306).

Conclusions

Elevated oxidative stress but not nitrative stress or poly (ADP-ribose) polymerase activation can be measured three years after pregnancy. The increased oxidative stress may reflect the cost of reproduction and possibly play a role in the increased metabolic risk observed in women with a history of severe gestational diabetes mellitus.

Effects of vitamin D on inflammatory and oxidative stress responses of human bronchial epithelial cells exposed to particulate matter

BACKGROUND

Particulate matter (PM) pollutant exposure, which induces oxidative stress and inflammation, and vitamin D insufficiency, which compromises immune regulation, are detrimental in asthma.

OBJECTIVES

Mechanistic cell culture experiments were undertaken to ascertain whether vitamin D abrogates PM-induced inflammatory responses of human bronchial epithelial cells (HBECs) through enhancement of antioxidant pathways.

METHODS

Transcriptome analysis, PCR and ELISA were undertaken to delineate markers of inflammation and oxidative stress; with comparison of expression in primary HBECs from healthy and asthmatic donors cultured with reference urban PM in the presence/absence of vitamin D.

RESULTS

Transcriptome analysis identified over 500 genes significantly perturbed by PM-stimulation, including multiple pro-inflammatory cytokines. Vitamin D altered expression of a subset of these PM-induced genes, including suppressing IL6. Addition of vitamin D suppressed PM-stimulated IL-6 production, although to significantly greater extent in healthy versus asthmatic donor cultures. Vitamin D also differentially affected PM-stimulated GM-CSF, with suppression in healthy HBECs and enhancement in asthmatic cultures. Vitamin D increased HBEC expression of the antioxidant pathway gene G6PD, increased the ratio of reduced to oxidised glutathione, and in PM-stimulated cultures decreased the formation of 8-isoprostane. Pre-treatment with vitamin D decreased CXCL8 and further decreased IL-6 production in PM-stimulated cultures, an effect abrogated by inhibition of G6PD with DHEA, supporting a role for this pathway in the anti-inflammatory actions of vitamin D.

CONCLUSIONS

In a study using HBECs from 18 donors, vitamin D enhanced HBEC antioxidant responses and modulated the immune response to PM, suggesting that vitamin D may protect the airways from pathological pollution-induced inflammation.

Corneal endothelial changes in patients with vitamin D deficiency

Purpose:

The purpose of this study is to evaluate the effect of vitamin D deficiency on corneal endothelial layer using specular microscopy.

Methods:

Fifty-eight eyes of 58 patients whose vitamin D level was below 15 ng/ml and who had no ocular pathology were included in the study (Group 1). Forty eyes of 40 age-and sex-matched subjects were enrolled as control group (Group 2). Corneal endothelial cell density (CD), coefficient of variation (CV), hexagonal cell ratio (HEX), and central corneal thickness (CCT) were measured using specular microscopy (Konan Medical Inc., Nishinomiya, Japan). The obtained data were compared between the groups.

Results:

There was no significant difference between the groups in terms of age and gender (P = 0.344, P = 0.399, respectively). The mean CD value was 2772.79 ± 202.21 cells/mm² in Group 1 and 2954.97 ± 116.89 cells/mm² in Group 2 (P = 0.001). The mean CV value was 30.31 ± 3.65 in Group 1 and 28.20 ± 2.71 in Group 2 (P = 0.003). The mean HEX value was 46.56 ± 6.32 in Group 1 and 51.07 ± 5.28 in Group 2 (P = 0.001). The mean CCT value was 555.87 ± 36.90 μ in group 1 and 549.0 ± 37.39 μ in Group 2 (P = 0.96).

Conclusion:

Vitamin D deficiency may affect the corneal endothelial layer. Patients with vitamin D deficiency should be evaluated for endothelial parameters in particular before an intraocular surgery. Further studies are needed to confirm our results.

Vitamin D Deficiency in Chronic Kidney Disease: Recent Evidence and Controversies

Vitamin D (VD) is a pro-hormone essential for life in higher animals. It is present in few types of foods and is produced endogenously in the skin by a photochemical reaction. The final step of VD activation occurs in the kidneys involving a second hydroxylation reaction to generate the biologically active metabolite 1,25(OH)₂-VD. Extrarenal 1α-hydroxylation has also been described to have an important role in autocrine and paracrine signaling. Vitamin D deficiency (VDD) has been in the spotlight as a major public healthcare issue with an estimated prevalence of more than a billion people worldwide. Among individuals with chronic kidney disease (CKD), VDD prevalence has been reported to be as high as 80%. Classically, VD plays a pivotal role in calcium and phosphorus homeostasis. Nevertheless, there is a growing body of evidence supporting the importance of VD in many vital non-skeletal biological processes such as endothelial function, renin-angiotensin-aldosterone system modulation, redox balance and innate and adaptive immunity. In individuals with CKD, VDD has been associated with albuminuria, faster progression of kidney disease and increased all-cause mortality. Recent guidelines support VD supplementation in CKD based on extrapolation from cohorts conducted in the general population. In this review, we discuss new insights on the multifactorial pathophysiology of VDD in CKD as well as how it may negatively modulate different organs and systems. We also critically review the latest evidence and controversies of VD monitoring and supplementation in CKD patients.

Association of Serum Vitamin D Level and Carotid Atherosclerosis: A Systematic Review and Meta-analysis

Vitamin D deficiency is associated with an increased risk of subclinical atherosclerosis. To explore the potential link of the serum vitamin D level with carotid atherosclerosis, this meta-analysis assessed the correlation between vitamin D and carotid intima-media thickness as well as carotid atherosclerotic plaque. PubMed, Embase, Web of Science, and Cochrane Library databases were searched until the end of March 2017. Clinical studies investigating the relationship between vitamin D and carotid atherosclerosis were included. The outcome data were extracted according to the inclusion criteria and pooled for an effect estimate by a random-effects model. Of the 506 initially retrieved studies, 11 studies involving a total of 16,434 participants were included in the meta-analysis. Newcastle-Ottawa Quality Assessment Scale scores suggested that the included studies were of high quality. The pooled effects estimate showed that the serum vitamin D level was negatively associated with carotid atherosclerosis (odds ratio, 0.95; 95% confidence interval [CI], 0.93-0.96), with substantial heterogeneity among the individual studies (I²  = 54%). Furthermore, a subgroup analysis suggested that hypovitaminosis D was associated with an 0.85-fold decrease in the odds of having a higher carotid intima-media thickness (95% CI, 0.76-0.96; P < .05; I²  = 69%). Additionally, the pooled analysis also indicated that the serum vitamin D level was a protective factor against increased carotid plaque (odds ratio, 0.95; 95% CI, 0.93-0.97; P < .05; I²  = 29%). Funnel plots and the Egger regression test showed the absence of a publication bias. In this meta-analysis, we comprehensively revealed a close link between vitamin D deficiency and carotid atherosclerosis. Patients with hypovitaminosis D might have extra requirements for preventive and therapeutic measures against early atherosclerosis, thus reducing the cardiovascular disease risk in the long term.

Effects of body fat mass and therapeutic weight loss on vitamin D status in privately owned adult dogs

More than one-third of humans and companion dogs in Western societies are overweight or obese. In people, vitamin D deficiency is widespread and associated with obesity, a now recognised inflammatory state. Low vitamin D status occurs in dogs with inflammatory conditions, but its relationship with obesity has not been investigated. In otherwise healthy privately owned adult dogs of ideal body condition (control, n 7) and dogs with overweight to obese body condition (treatment, n 8), serum 25-hydroxyvitamin D (25(OH)D) concentration and body composition as inferred from ²H-labelled water dilution space were evaluated. Subsequently, the dogs were transitioned to a commercial canine therapeutic weight-loss diet; control dogs were fed to maintain body weight and treatment dogs were energy-restricted to achieve a safe weight-loss rate. Thereafter, serum 25(OH)D concentration was re-evaluated 8 weeks after diet transition, and at the study end, which was 6 months or when ideal body condition was achieved. At study end, body composition analysis was repeated. Initial body condition scores and percentage body fat were positively correlated (ρ = 0·891; P < 0·001). However, percentage body fat and serum 25(OH)D concentration were not significantly correlated. Final serum 25(OH)D concentrations were greater (P < 0·05) than initial concentrations for control and treatment groups, indicating a diet but not weight-loss effect on vitamin D status. These findings suggest that vitamin D status of dogs is not affected by obesity or loss of body fat with therapeutic weight reduction.

Association between hematological profile and serum 25-hydroxyvitamin D levels and FokI polymorphism in individuals with cystic fibrosis

ABSTRACT Objective The present study aimed at investigating the association between hematological profile and serum 25-hydroxyvitamin D (25[OH]D) levels and Fokl polymorphism of the vitamin D receptor gene in individuals with Cystic Fibrosis. Methods A cross-sectional study that involved 18 men and women aged 0-25 years with Cystic Fibrosis. Socio-demographic information and the factors associated with sun exposure were obtained. Weight, height, and arm circumference were also measured. Blood sample was collected for the analysis of biochemical parameters (25[OH]D, parathyroid hormone, and calcium levels and blood count) and for the validation of the presence of FokI polymorphism in the vitamin D receptor gene. Results Among the participants, 33.33% (n=6) had vitamin D deficiency (19.60±6.180 ng/mL), and 27.8% (n=5) presented with anemia and low weight for age. In terms of genotype, 5.6% (n=1) presented with the FF genotype, 72.3% (n=13) had the Ff genotype, and 22.2% (n=4) had the ff genotype. Serum 25(OH)D levels were associated with hemoglobin (p=0.008) and hematocrit (p=0.019) levels and leukocyte count (p=0.0114). No association was observed between 25(OH)D levels and the genotypes (FF, Ff, and ff) (p=0.2451). In addition, an association was observed between FokI polymorphism and the total leukocyte count (p=0.01). Conclusion An association was observed between serum 25(OH)D levels and hemoglobin and hematocrit levels and leukocyte count in individuals with Cystic Fibrosis. Moreover, FokI polymorphism was associated with total leukocyte count.