Vitamin D deficiency: concern for rheumatoid arthritis and COVID-19?

Vitamin D is an immunomodulatory hormone with an established role in calcium and phosphate metabolism and skeletal mineralization. Evidence showing its immunological benefits by regulating essential components of the innate and adaptive immune system is prevalent. Vitamin D deficiency is reported worldwide and is thereby found to be associated with various immune-related diseases. Rheumatoid Arthritis and COVID-19 are two such diseases, sharing a similar hyperinflammatory response. Various studies have found an association of lower Vitamin D levels to be associated with both these diseases. However, contrasting data is also reported. We review here the available scientific data on risk factor association and supplementation benefits of Vitamin D in Rheumatoid Arthritis and COVID-19, intending to critically evaluate the literature.

     

BCG Vaccination: A Role for Vitamin D?

Background

BCG vaccination is administered in infancy in most countries with the aim of providing protection against tuberculosis. There is increasing interest in the role of vitamin D in immunity to tuberculosis. This study objective was to determine if there was an association between circulating 25(OH)D concentrations and BCG vaccination status and cytokine responses following BCG vaccination in infants.

Methods

Blood samples were collected from UK infants who were vaccinated with BCG at 3 (n = 47) and 12 (n = 37) months post BCG vaccination. These two time-points are denoted as time-point 1 and time-point 2. Two blood samples were also collected from age-matched unvaccinated infants (n = 32 and 28 respectively), as a control group. Plasma vitamin D concentrations (25(OH)D) were measured by radio-immunoassay. The cytokine IFNγ was measured in supernatants from diluted whole blood stimulated with M.tuberculosis (M.tb) PPD for 6 days.

Results

58% of infants had some level of hypovitaminosis (25(OH)D <30ng/ml) at time-point 1, and this increased to 97% 9 months later. BCG vaccinated infants were almost 6 times (CI: 1.8–18.6) more likely to have sufficient vitamin D concentrations than unvaccinated infants at time-point 1, and the association remained strong after controlling for season of blood collection, ethnic group and sex. Among vaccinees, there was also a strong inverse association between IFNγ response to M.tb PPD and vitamin D concentration, with infants with higher vitamin D concentrations having lower IFNγ responses.

Conclusions

Vitamin D may play an immuno-regulatory role following BCG vaccination. The increased vitamin D concentrations in BCG vaccinated infants could have important implications: vitamin D may play a role in immunity induced by BCG vaccination and may contribute to non-specific effects observed following BCG vaccination.     

Vitamin D and autoimmunity: is vitamin D status an environmental factor affecting autoimmune disease prevalence?

The environment in which the encounter of antigen with the immune system occurs determines whether tolerance, infectious immunity, or autoimmunity results. Geographical areas with low supplies of vitamin D (for example Scandinavia) correlate with regions with high incidences of multiple sclerosis, arthritis, and diabetes. The active form of vitamin D has been shown to suppress the development of autoimmunity in experimental animal models. Furthermore, vitamin D deficiency increases the severity of at least experimental autoimmune encephalomyelitis (mouse multiple sclerosis). Targets for vitamin D in the immune system have been identified, and the mechanisms of vitamin D-mediated immunoregulation are beginning to be understood. This review discusses the possibility that vitamin D status is an environmental factor, which by shaping the immune system affects the prevalence rate for autoimmune diseases such as multiple sclerosis, arthritis, and juvenile diabetes.     

Is Vitamin D the Fountain of Youth?

ObjectiveTo review the role of vitamin D deficiency for both classic and “nonclassic” effects and raise the caution that association does not prove causation.MethodsThe pertinent literature regarding vitamin D and its effects on bone, muscle function, immune function, glucose tolerance, cancer risk, and development of cardiovascular disease and other conditions is reviewed. In addition, the limitations of observational studies are discussed.ResultsVitamin D inadequacy is common worldwide and classically causes osteomalacia and rickets. More recently, the contribution of low vitamin D status to increased falls and fracture risk has become appreciated. Additionally, nonclassic effects of vitamin D inadequacy are being recognized, and low vitamin D status is being potentially associated with a multitude of conditions (including Alzheimer disease, osteoarthritis, multiple sclerosis, and hypertension) and higher overall mortality. It is important to recognize that associations in observational studies can be due to chance, bias, or confounders or may be indicative of causality.ConclusionBecause vitamin D deficiency has been established to have adverse musculoskeletal consequences, optimization of vitamin D status, for both the individual patient and the overall population, is indicated. (Endocr Pract. 2009;15:590-596)     

Vitamin D: a hormone for all seasons--how much is enough?

Further understanding of its endocrine mechanisms and increased evidence for autocrine/paracrine actions has recently enhanced our knowledge of the biological activities of the vitamin D metabolite 1,25-dihydroxyvitamin D (1,25(OH)2D). The recognition of the contribution of vitamin D depletion to increased risk of osteoporosis, and most importantly the risk of hip fracture in the elderly, has increased the clinical significance of clinical laboratory testing for vitamin D status. Research has revealed that at least three genes contribute to vitamin D activity within tissues. These are the vitamin D receptor as well as two major vitamin D metabolising enzymes, CYP27B1, responsible for synthesis of 1,25(OH)2D and CYP24, responsible for catabolism of vitamin D metabolites. Current research focuses on the contribution of vitamin D metabolism to increasing vitamin D activity. This is of particular interest in bone forming cells where increased 1,25(OH)2D activity has been proposed to contribute to strengthening the skeleton. As well, solid tumours such as prostate, breast and colon cancers are another increasing area of vitamin D research. The major issues for the clinical laboratory in vitamin D testing include defining clinical decision limits for the interpretation of serum 25-hydroxyvitamin D (25OHD) levels and improving the precision and accuracy of this assay.     

Vitamin D Deficiency and Leisure Time Activities in the Elderly: Are All Pastimes the Same?

Background

Optimal vitamin D status is important for overall health and well-being, particularly in the elderly. Although vitamin D synthesis in the skin declines with age, exposure to sunlight still seems to help older-aged adults to achieve adequate serum 25-hydroxyvitamin D (25OHD) levels. Elderly people would therefore benefit from outdoor leisure activities, but the effects of different types of pastime on serum 25OHD levels have yet to be thoroughly investigated.

Aims

To assess the association of different pastimes with 25OHD deficiency in elderly subjects.

Methods

A sample of 2,349 community-dwelling elderly individuals (1,389 females and 960 males) enrolled in the Progetto Veneto Anziani was analyzed. Brisk walking, cycling, gardening and fishing were classed as outdoor activities, and dancing and gym workouts as indoor pastimes. Any activities undertaken for at least 1 hour/week during the previous month were considered as being practiced regularly. Logistic regression models were used to estimate the association between different pastimes and 25OHD deficiency.

Results

Serum 25OHD levels were significantly higher in individuals who engaged in outdoor pastimes (+25% in women, +27.7% in men) compared to those who did not. In particular, subjects regularly practicing gardening or cycling had higher serum 25OHD levels than those who did not, whereas 25OHD levels differed little between subjects who did or did not undertake indoor activities. Among the outdoor pastimes considered, logistic regression analysis confirmed a lower likelihood of vitamin D deficiency (25OHD<50 nmol/L) for cyclists (OR 0.51, 95% CI 0.37–0.69 in women; OR 0.50, 95% CI 0.29–0.87 in men) and gardeners (OR 0.62, 95% CI 0.47–0.83 in women; OR 0.46, 95% CI 0.26–0.80), but not for brisk walkers.

Conclusions

Regular cycling and gardening reduce the likelihood of inadequate vitamin D status in Caucasian elderly people, irrespective of their age, BMI and comorbidities, and of the season of the year.     

Vitamin D — Soltriol The heliogenic steroid hormone: Somatotrophic activator and modulator

Summary Evidence from autoradiographic studies with ³H 1,25(OH)₂ vitamin D₃ (soltriol) about its many sites of nuclear binding and multiple actions suggests that the traditional view of vitamin D and calcium is too limited and requires modification. A new concept has been developed which proposes that the skin-derived hormone of sunshine, soltriol, is a somatotrophic activator and modulator that affects all vital systems. Regulation of calcium homeostasis is only one of its many actions. Target tissues for soltriol include not only bone, intestine and kidney, but also brain, spinal cord, pituitary, thyroid, endocrine pancreas, adrenal medulla, enteroendocrine cells, thymus, and male and female reproductive organs. Accordingly, actions of soltriol involve effects on autonomic and endocrine regulation with changes in tissue and blood hormone levels, innervation of skeletal muscle, immune and stress response, digestion, blood formation, fertility, pregnancy and lactation, general energy metabolism, mental processes and mood, and others. The skin-mediated transduction of short-wave sunlight induces a purposeful modulation of growth, reproduction and other biological activities in tune with the conditions of the sun cycle and season. Synthesis and actions of vitamin D₃-soltriol are dependent not only on the amount of sunlight, but also on the availability of precursor in the skin and access of sunlight, the rate of hydroxylation in liver and kidney, and the modulation of these events by the endocrine status, in particular growth and reproduction. A concept of a five-level control of soltriol synthesis is proposed, in which the hydroxylation steps provide for a sensitive tuning. Relationships between the heliogenic skin-derived hormonal system and the helioprivic pineal-derived hormonal system are recognized and a comprehensive concept of the endocrinology of sunlight and darkness is pointed out.     

“Anticonvulsant Action” of Vitamin D in Epileptic Patients? A Controlled Pilot Study

The frequency of epileptic seizures was observed in a controlled therapeutic trial on 23 epileptic inpatients before and after treatment with vitamin D₂ or placebo in addition to anticonvulsant drugs. The number of seizures was reduced during treatment with vitamin D₂ but not with placebo. The effect was unrelated to changes in serum calcium or magnesium. The results may support the concept that epileptics should be treated prophylactically with vitamin D.     

Mitochondrial dysfunction: A potential link between neuroinflammation and neurodegeneration?

Dysfunctional mitochondria are thought to play a cardinal role in the pathogenesis of various neurological disorders, such as multiple sclerosis, Alzheimer’s disease, Parkinson’s disease and stroke. In addition, neuroinflammation is a common denominator of these diseases. Both mitochondrial dysfunction and neuroinflammatory processes lead to increased production of reactive oxygen species (ROS) which are detrimental to neurons. Therefore, neuroinflammation is increasingly recognized to contribute to processes underlying neurodegeneration. Here we describe the involvement of mitochondrial (dys)function in various neurological disorders and discuss the putative link between mitochondrial function and neuroinflammation.     

Vitamin D? Supplementation in Batswana Children and Adults with HIV: A Pilot Double Blind Randomized Controlled Trial

ObjectivesSince vitamin D insufficiency is common worldwide in people with HIV, we explored safety and efficacy of high dose cholecalciferol (D₃) in Botswana, and evaluated potential modifiers of serum 25 hydroxy vitamin D change (Δ25D).DesignProspective randomized double-blind 12-week pilot trial of subjects ages 5.0–50.9 years.MethodsSixty subjects randomized within five age groups to either 4000 or 7000IU per day of D₃ and evaluated for vitamin D, parathyroid hormone, HIV, safety and growth status. Efficacy was defined as serum 25 hydroxy vitamin D (25D) ≥32ng/mL, and safety as no simultaneous elevation of serum calcium and 25D. Also assessed were HIV plasma viral RNA viral load (VL), CD4%, anti-retroviral therapy (ART) regime, and height-adjusted (HAZ), weight-adjusted (WAZ) and Body Mass Index (BMIZ) Z scores.ResultsSubjects were 50% male, age (mean±SD) 19.5±11.8 years, CD4% 31.8±10.4, with baseline VL log₁₀ range of <1.4 to 3.8 and VL detectable (>1.4) in 22%. From baseline to 12 weeks, 25D increased from 36±9ng/ml to 56±18ng/ml (p<0.0001) and 68% and 90% had 25D ≥32ng/ml, respectively (p = 0.02). Δ25D was similar by dose. No subjects had simultaneously increased serum calcium and 25D. WAZ and BMIZ improved by 12 weeks (p<0.04). HAZ and CD4% increased and VL decreased in the 7000IU/d group (p<0.04). Younger (5–13y) and older (30–50y) subjects had greater Δ25D than those 14–29y (26±17 and 28±12 vs. 11±11ng/ml, respectively, p≤0.001). Δ25D was higher with efavirenz or nevirapine compared to protease inhibitor based treatment (22±12, 27±17, vs. 13±10, respectively, p≤0.03).ConclusionsIn a pilot study in Botswana, 12-week high dose D₃ supplementation was safe and improved vitamin D, growth and HIV status; age and ART regimen were significant effect modifiers.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT02189902","term_id":"NCT02189902"}}NCT02189902     

Mitochondrial stress: a bridge between mitochondrial dysfunction and metabolic diseases?

Under pathophysiological conditions such as obesity, excessive oxidation of nutrients may induce mitochondrial stress, leading to mitochondrial unfolded protein response (UPR^mt) and initiation of a retrograde stress signaling pathway. Defects in the UPR^mt and the retrograde signaling pathways may disrupt the integrity and homeostasis of the mitochondria, resulting in endoplasmic reticulum stress and insulin resistance. Improving the capacity of mitochondria to reduce stress may be an effective approach to improve mitochondria function and to suppress obesity-induced metabolic disorders such as insulin resistance and type 2 diabetes.     

Vitamin D Deficiency in Children with a Chronic Illness–Seasonal and Age-Related Variations in Serum 25-hydroxy Vitamin D Concentrations

Introduction

Children and adolescents with a chronic illness have potential risk factors for vitamin D deficiency. An optimal vitamin D status might have multiple health effects. This study evaluated vitamin D status and its association with age, gender, and season in a large cohort of chronically ill Finnish patients at a tertiary pediatric outpatient clinic. A cross-sectional register-based study was carried out, involving altogether 1351 children (51% boys, age range 0.2–18 years), who visited the outpatient clinic during 2007–2010 and had their vitamin D status (S-25-OHD) determined. A post-doc analysis was conducted to identify predisposing and preventing factors for vitamin D deficiency.

Results

Almost half (47%) of the S-25-OHD values were consistent with subnormal vitamin D status (S-25-OHD <50 nmol/L) while only 12% were >80 nmol/L. Age and season were the most important determinants for S-25-OHD concentration. Mean S-25-OHD concentration differed between age groups (Kruskal-Wallis; p<0.001), adolescents being at highest risk for vitamin D insufficiency. Young age and vitamin D supplementation were preventive factors for deficiency, while non-Finnish ethnic background was a predisposing factor. S-25-OHD showed significant seasonal variation in children older than 6 years. In the whole cohort, S-25-OHD was on average 13 nmol/L higher in summer than in winter, and the prevalence of vitamin D deficiency ( =  S-25-OHD <37.5 nmol/l) varied from 11% in summer to 29% in winter.

Conclusions

The finding that almost half of the studied Finnish children with a chronic illness had suboptimal vitamin D status is alarming. Inferior vitamin D status was noted in adolescents compared with younger children, suggesting that imbalance between intake and requirement evolves with age. Although less common during summer, subnormal vitamin D status was still observed in 28% of those evaluated in summer. Clinicians should identify individuals at risk and actively recommend vitamin D supplementation.     

Improvement in Pancreatic β-Cell Function with Vitamin D and Calcium Supplementation in Vitamin D-Deficient Nondiabetic Subjects

ObjectiveThere are varied reports on the effect of vitamin D supplementation on β-cell function and plasma glucose levels. The objective of this study was to examine the effect of vitamin D and calcium supplementation on β-cell function and plasma glucose levels in subjects with vitamin D deficiency.MethodsNondiabetic subjects (N = 48) were screened for their serum 25-hydroxyvitamin D (25-OHD), albumin, creatinine, calcium, phosphorus, alkaline phosphatase, and intact parathyroid hormone (PTH) status. Subjects with 25-OHD deficiency underwent a 2-hour oral glucose tolerance test. Cholecalciferol (9,570 international units [IU]/day; tolerable upper intake level, 10,000 IU/day; according to the Endocrine Society guidelines for vitamin D supplementation) and calcium (1 g/day) were supplemented.ResultsThirty-seven patients with 25-OHD deficiency participated in the study. The baseline and postvitamin D/calcium supplementation and the difference (corrected) were: serum calcium, 9 ± 0.33 and 8.33 ± 1.09 mg/dL (− 0.66 ± 1.11 mg/dL); 25-OHD, 8.75 ± 4.75 and 36.83 ± 18.68 ng/mL (28.00 ± 18.33 ng/mL); PTH, 57.9 ± 29.3 and 36.33 ± 22.48 pg/mL (− 20.25 ± 22.45 pg/mL); fasting plasma glucose, 78.23 ± 7.60 and 73.47 ± 9.82 mg/dL (− 4.88 ± 10.65 mg/dL); and homeostasis model assessment-2–percent β-cell function C-peptide secretion (HOMA-2–%B C-PEP), 183.17 ± 88.74 and 194.67 ± 54.71 (11.38 ± 94.27). Significant differences were observed between baseline and post-vitamin D/calcium supplementation serum levels of corrected calcium (Z, − 3.751; P < .0001), 25-OHD (Z, − 4.9; P < .0001), intact PTH (Z, − 4.04; P < .0001), fasting plasma glucose (Z, − 2.7; P < .007), and HOMA-2–%B C-PEP (Z, − 1.923; P < .05) as determined by Wilcoxon signed rank test. Insulin resistance as measured by HOMA was unchanged.ConclusionOptimizing serum 25-OHD concentrations and supplementation with calcium improves fasting plasma glucose levels and β-cell secretory reserve. Larger randomized control studies are needed to determine if correction of 25-OHD deficiency will improve insulin secretion and prevent abnormalities of glucose homeostasis. (Endocr Pract. 2014;20:129-138)     

Vitamin D regulation of immune function in the gut: why do T cells have vitamin D receptors?

Low vitamin D status is associated with an increased risk of immune-mediated diseases like inflammatory bowel disease (IBD) in humans. Experimentally vitamin D status is a factor that shapes the immune response. Animals that are either vitamin D deficient or vitamin D receptor (VDR) deficient are prone to develop IBD. Conventional T cells develop normally in VDR knockout (KO) mice but over-produce IFN-γ and IL-17. Naturally occurring FoxP3+ regulatory T cells are present in normal numbers in VDR KO mice and function as well as wildtype T regs. Vitamin D and the VDR are required for the development and function of two regulatory populations of T cells that require non-classical MHC class 1 for development. The two vitamin D dependent cell types are the iNKT cells and CD4/CD8αα intraepithelial lymphocytes (IEL). Protective immune responses that depend on iNKT cells or CD8αα IEL are therefore impaired in the vitamin D or VDR deficient host and the mice are more susceptible to immune-mediated diseases in the gut.     

Mitochondrial dysfunction and oxidative stress: a contributing link to acquired epilepsy?

Mitochondrial dysfunction and oxidative stress contribute to several neurologic disorders and have recently been implicated in acquired epilepsies such as temporal lobe epilepsy (TLE). Acquired epilepsy is typically initiated by a brain injury followed by a "latent period" whereby molecular, biochemical and other cellular alterations occur in the brain leading to chronic epilepsy. Mitochondrial dysfunction and oxidative stress are emerging as factors that not only occur acutely as a result of precipitating injuries such as status epilepticus (SE), but may also contribute to epileptogenesis and chronic epilepsy. Mitochondria are the primary site of reactive oxygen species (ROS) making them uniquely vulnerable to oxidative damage that may affect neuronal excitability and seizure susceptibility. This mini-review provides an overview of evidence suggesting the role of mitochondrial dysfunction and oxidative stress as acute consequences of injuries that are known to incite chronic epilepsy and their involvement in the chronic stages of acquired epilepsy.