Lack of a relation between serum 25-hydroxyvitamin D concentrations and asthma in adolescents

Association between Vitamin D Levels, Puberty Timing, and Age at Menarche

Pubertal development represents the process of physical maturation where an adolescent reaches sexual maturity and attains reproductive function. The effects of vitamin D are mainly mediated by the vitamin D receptor (VDR), which is expressed in almost all body cells, including the ovary and human pituitary gland and animal hypothalamus. Thus, vitamin D has gained great interest as pathogenic factor of pubertal disorders and fertility. This narrative review aimed to provide a broad overview of the available literature regarding the association between vitamin D levels, puberty timing, and age at menarche. A review of the data on the involvement of micronutrient deficiency, as a modifiable cause of pubertal disorders, is important for the prediction and prevention of deficiencies as well as for fertility protection and should be considered a public health priority. Reported data support that vitamin D is a regulator of neuroendocrine and ovarian physiology and, more in detail, a deficiency of vitamin D is involved in altered pubertal timing. Considering the long-term consequences of early pubertal development and early menarche, the detection of modifiable causes is crucial in preventive strategies. Future studies in humans and with an increased scale are needed to elucidate the vitamin D role in sexual maturation and puberty development.

Immunomodulatory actions of vitamin D in various immune-related disorders: a comprehensive review

For many years, vitamin D has been acknowledged for its role in maintaining calcium and phosphate balance. However, in recent years, research has assessed its immunomodulatory role and come up with conflicting conclusions. Because the vitamin D receptor is expressed in a variety of immune cell types, study into the precise role of this molecule in diseases, notably autoimmune disorders, has been made possible. The physiologically activated version of vitamin D also promotes a tolerogenic immunological condition in addition to modulating innate and acquired immune cell responses. According to a number of recent studies, this important micronutrient plays a complex role in numerous biochemical pathways in the immune system and disorders that are associated with them. Research in this field is still relatively new, and some studies claim that patients with severe autoimmune illnesses frequently have vitamin D deficiencies or insufficiencies. This review seeks to clarify the most recent research on vitamin D's immune system-related roles, including the pathophysiology of major disorders.

Association of High-Sensitivity C-Reactive Protein and Vitamin D with Bronchial Asthma

Background: Bronchial asthma (BA) is a common lung illness and a significant health concern affecting over 315 million individuals globally. Asthma involves three main pathologies: airways hyperresponsiveness (AHR), inflammation, and remodeling. VitD has a forceful immunomodulatory effect able of reducing inflammatory responses in many cells intricate in BA. Deficiency of vitD has been linked with much inflammation and global worsening of asthmatic patients. C-reactive protein (CRP) is elevated in primary stages of inflammation of BA and high serum CRP values are observed with impaired pulmonary function and AHR. For that reason, it is sensible to explore the role of vitD in BA via its associations with CRP. This comparative study was aimed to evaluate the relationship between serum levels of HSCRP and vitD in patients with asthma. Patients and Methods: This is a case-control study conducted on 127 asthmatic patients with 113 (sex/aged matching) healthy control. The FeNo results had obtained in private centers, according to the ''guidelines of the American Thoracic Society (ATS)''. All participants had blood analysis of HSCRP and correlated with FeNo measures. VitD Values were classified as sufficient (>30ng/ml), insufficient (20 to 30ng/ml), and deficient (<20ng/mL) based on the preceding reference. Statistical Package for Social Sciences (SPSS/23-IBM) had used. The chi-squared test had used for univariate investigation, and a t-test had completed detecting variations between the studied groups, treatment groups, and genders. The outcomes had calculated at a 95% CI and had assigned as significant for all variables. The categorization accuracy of HSCRP, vitD, and FeNo measures had been investigated under the ''ROC curves'' for their diagnostic fitness to decide asthma prediction. Results Compared to the control group, the mean FeNo levels were significantly higher in asthmatics (p-0.001). Vitamin D mean levels were parallel between the study groups (p>0.05). The mean HSCRP levels were significantly (p-0.03) higher among asthmatics. Around 40% of all participants had lower than normal levels of serum VitD and <10% only revealed deficient levels. There was no effect of history of the treatment of BA on the blood levels of vitD and HSCRP. There was a positive non-significant correlation of vitD with FeNo results (r-0.067, p-0.54) and negative non-significant (r-0.082, p-0.086) correlation of vitD with HSCRP. ROC-curve analysis showed a significant ability (p-0.001) of FeNo to distinguish asthma, with high accuracy, sensitivity and specificity: 0.967, 93.5%, 93.2%, at 95% CI [0.946-1.000], respectively. Likewise, ROC analysis of HSCRP revealed significant ability (p-0.001), but with lower accuracy (0.881), sensitivity (87.1%), and specificity (76.3%) at 95% CI [0.812-0.950] to distinguish asthma patients from healthy subjects. Unlikely, VitD had a non-significant (p-0.085) and lower ability to predict asthma from healthy participants showing AUC (0.612), sensitivity (54.8%), and specificity (68.3%) at 95% CI [0.488 -0.736]. Conclusion No relation or minor conflicting correlations between serum levels of vitD with asthma severity, treatment history, and inflammation (as indicated by HSCRP). Highly sensitive CRP is correlated with asthma.

Inherited iron overload disorders

Hereditary iron overload includes several disorders characterized by iron accumulation in tissues, organs, or even single cells or subcellular compartments. They are determined by mutations in genes directly involved in hepcidin regulation, cellular iron uptake, management and export, iron transport and storage. Systemic forms are characterized by increased serum ferritin with or without high transferrin saturation, and with or without functional iron deficient anemia. Hemochromatosis includes five different genetic forms all characterized by high transferrin saturation and serum ferritin, but with different penetrance and expression. Mutations in HFE, HFE2, HAMP and TFR2 lead to inadequate or severely reduced hepcidin synthesis that, in turn, induces increased intestinal iron absorption and macrophage iron release leading to tissue iron overload. The severity of hepcidin down-regulation defines the severity of iron overload and clinical complications. Hemochromatosis type 4 is caused by dominant gain-of-function mutations of ferroportin preventing hepcidin-ferroportin binding and leading to hepcidin resistance. Ferroportin disease is due to loss-of-function mutation of SLC40A1 that impairs the iron export efficiency of ferroportin, causes iron retention in reticuloendothelial cell and hyperferritinemia with normal transferrin saturation. Aceruloplasminemia is caused by defective iron release from storage and lead to mild microcytic anemia, low serum iron, and iron retention in several organs including the brain, causing severe neurological manifestations. Atransferrinemia and DMT1 deficiency are characterized by iron deficient erythropoiesis, severe microcytic anemia with high transferrin saturation and parenchymal iron overload due to secondary hepcidin suppression. Diagnosis of the different forms of hereditary iron overload disorders involves a sequential strategy that combines clinical, imaging, biochemical, and genetic data. Management of iron overload relies on two main therapies: blood removal and iron chelators. Specific therapeutic options are indicated in patients with atransferrinemia, DMT1 deficiency and aceruloplasminemia.

Predictive role of IL-17A/IL-10 ratio in persistent asthmatic patients on vitamin D supplement

Asthma is an airway inflammatory disorder. Vitamin (Vit) D is a potent immuno-modulator. It suppresses Interleukin (IL)-17 and induces IL-10. This study aims to investigate the role of IL-17A and IL-10 in predicting asthma control in case of Vit D supplementation. Seventy-nine patients enrolled in this study (42 patients received Vit D supplement and 37 patients did not receive the supplement). The enrolled patients were assessed at the beginning of this study and after 3 months. At the end of the study, there was a significant improvement in pulmonary function parameters in the Vit D supplemented group when compared to both the baseline values and the non-supplemented group. There was a significant decrease in serum IL-17A levels and a significant increase in serum IL-10 levels in comparison with the baseline values (p < 0.0001). The highest correlation of FEV1% improvement percentage was associated with the baseline IL-17A/IL-10 ratio (r = 0.65; p < 0.0001). The IL-17A/IL-10 ratio at a cutoff ≥ 2.66 had a sensitivity of 72.2% and a specificity of 83.3%. The IL-17A/IL-10 ratio had an adjusted odds ratio = 4.66 (p = 0.04). Vit D supplementation reduces the serum IL-17A levels and elevates the serum IL-10 levels in persistent asthmatic patients. So, Vitamin D can be used as an adjunct therapy side by side with the conventional asthma therapy. The IL-17A/IL-10 ratio seems to be a possible predictive biomarker for asthma improvement in patients depending on Vit D supplementation.

Vitamin D in pediatric age: consensus of the Italian Pediatric Society and the Italian Society of Preventive and Social Pediatrics, jointly with the Italian Federation of Pediatricians

Vitamin D plays a pivotal role in the regulation of calcium-phosphorus metabolism, particularly during pediatric age when nutritional rickets and impaired bone mass acquisition may occur.Besides its historical skeletal functions, in the last years it has been demonstrated that vitamin D directly or indirectly regulates up to 1250 genes, playing so-called extraskeletal actions. Indeed, recent data suggest a possible role of vitamin D in the pathogenesis of several pathological conditions, including infectious, allergic and autoimmune diseases. Thus, vitamin D deficiency may affect not only musculoskeletal health but also a potentially wide range of acute and chronic conditions. At present, the prevalence of vitamin D deficiency is high in Italian children and adolescents, and national recommendations on vitamin D supplementation during pediatric age are lacking. An expert panel of the Italian Society of Preventive and Social Pediatrics reviewed available literature focusing on randomized controlled trials of vitamin D supplementation to provide a practical approach to vitamin D supplementation for infants, children and adolescents.

Vitamin D supplementation improves FEV1 in patients of Bronchial Asthma

Background and Objective

Vitamin D deficiency has strong association with various respiratory disorders in which bronchial asthma is one of them. The objective was to determine the efficacy of vitamin D supplementation in cases with bronchial asthma.

Methods

This case control study was conducted at private clinical set up of district, Rahim Yar Khan from August to October 2016 in which 100 cases of bronchial asthma were randomly divided into Group-A and Group-B each contained 50 patients. Group-A was given placebo and Group-B with vitamin D in a dose of 50,000 units per day orally. Both the groups were followed in terms of improvement in FEV1 at 1, 2 and 3 months.

Results

There was no significant difference in both groups in terms of BMI and duration of asthma at start of study. The mean pre treatment vitamin D level of Group-A was 14.23±1.66 and of Group-B, 15.30±2.05 ng/dl (p= 0.23). FEV1 in pre treatment Group-A was 64.35±3.16 and of Group-B was 62.35±2.16 with p= 0.95. There was no significant difference in terms of FEV1 in both the groups at one month (p= 0.32). While at two months it was significantly higher in Group-B with p= 0.04. At 3 months the final outcome was seen where the post treatment FEV1 in Group-A was 66.13±2.75 and in Group-B, 75.15±2.04 with p value of 0.001.

Conclusion

Vitamin D supplementation improves FEV1 significantly at two months and these can be even highly significant if it is extended up to 3 months.

Rapid vs Maintenance Vitamin D Supplementation in Deficient Children With Asthma to Prevent Exacerbations

BACKGROUND

Whether vitamin D reduces clinically important exacerbations of childhood asthma remains uncertain. We compared rapid to maintenance vitamin D repletion analyzed by baseline vitamin D level.

METHODS

Children presenting to the ED with moderate-to-severe asthma exacerbations and vitamin D levels ≤ 25 ng/mL underwent masked randomization, and then open dosing to either IM+oral (the latter daily) therapy or daily oral-only therapy, and were followed for 12 months. The primary outcome was patient-initiated unplanned visits for asthma exacerbations, examined two ways: cumulative proportions with an exacerbation, and average exacerbation frequency. As this was a nutrient study, we analyzed treatment groups by quartile of baseline vitamin D level, collecting repeat levels and clinical observations at 3, 6, 9, and 12 months after enrollment.

RESULTS

One hundred and sixteen patients in the IM+oral cohort vs 115 in the oral-only cohort had similar mean (SD) baseline levels: 15.1 (5.4) vs 15.8 (5.2) ng/mL (range, 3-25 ng/mL). There was no difference in the primary outcome over the entire 12-month observation period. However, rapid IM+oral supplementation significantly reduced unplanned visits for asthma exacerbations for children with baseline levels of 3 to 11 ng/mL during the initial 3 months: the relative exacerbation rate for the IM+oral cohort compared with the oral-only cohort at 3 months was 0.48 (95% CI, 0.28-0.89; P = .008); average exacerbation frequency per child analysis, relative rate 0.36 (95% CI, 0.13-0.87; P = .017). Otherwise, there were no significant differences between groups.

CONCLUSIONS

Rapid compared to maintenance vitamin D supplementation for children with the lowest levels resulted in short- but not long-term reduction in asthma exacerbations.

25-Hydroxyvitamin D concentrations, asthma and eczema in childhood: The generation R study

BACKGROUND & AIMS

A role of vitamin D in the development of respiratory and allergic disease in children remains unclear. It may be likely that vitamin D has an effect on airway inflammation, but only few studies examined the effect in children. We aimed to examine whether serum 25-hydroxyvitamin D (25(OH) vitamin D) concentrations are associated with the fraction of exhaled nitric oxide (FeNO), airway interrupter resistance (Rint), physician diagnosed asthma ever, wheezing and eczema in a population-based cohort study in 6 year old children.

METHODS

Serum 25(OH) vitamin D concentration was assessed in 3815 children. 25(OH) vitamin D concentrations ≥75 nmol/L were considered as sufficient, between 50 and 75 nmol/L as insufficient, and <50 nmol/L as deficient. FeNO and Rint were measured at the research center. Data on physician diagnosed asthma, wheezing, and eczema were obtained by parent-reported questionnaires.

RESULTS

In comparison with sufficient 25(OH) vitamin D concentration, deficient concentrations were associated with elevated FeNO of ≥25 ppb (OR: 2.54; 95% CI: 1.34-4.80). In addition, deficient and insufficient 25(OH) vitamin D concentrations were associated with a lower Rint (Z-score: -1.26; 95% CI: -1.66 to -0.85) (ß: -0.75; 95% CI: -1.08 to -0.42), and increased risks of eczema (OR: 1.65; 95% CI: 1.13-2.41) (OR: 1.44; 95% CI: 1.06-1.95). Insufficient 25(OH) vitamin D concentration were associated with a decreased risk of physician diagnosed asthma ever (OR: 0.59; 95% CI: 0.38-0.94).

CONCLUSIONS

Our results indicate that lower 25(OH) vitamin D levels are associated with elevated FeNO levels, but lower Rint values. Lower 25(OH) vitamin D levels are also associated with a decreased risk for asthma diagnoses but an increased risk for eczema.

Vitamin D and asthma: current perspectives

PURPOSE OF REVIEW

To review the current evidence on the relationship between vitamin D and asthma.

RECENT FINDINGS

The rising morbidity and tremendous socioeconomic burden of asthma have prompted efforts to seek modifiable environmental and nutritional factors that contribute to the asthma epidemic. The association between low levels of vitamin D and asthma has been supported by many, but not all observational and epidemiologic studies. Recently, several controlled clinical trials have been undertaken to explore the effect of vitamin D supplementation on asthma control and respiratory tract infections. While some trials support the beneficial role of vitamin D supplementation in reducing asthma severity in children, several trials have found no beneficial role in adults.

SUMMARY

Given the high prevalence of vitamin D insufficiency in children and adults worldwide and recent randomized controlled trials of vitamin D in asthma, supplementation with vitamin D cannot be recommended as adjunctive therapy for asthma.

Endotoxin exposure, serum vitamin D, asthma and wheeze outcomes

BACKGROUND

Endotoxin has been shown to induce neutrophilic asthma and wheeze after binding toll-like receptor 4 to produce pro-inflammatory cytokines. Animal models have demonstrated that vitamin D might inhibit lipopolysaccharide-induced cytokines. However, whether endotoxin exposure and serum vitamin D deficiency interact to affect asthma and wheeze in humans has never been investigated in an epidemiological study.

METHODS

Joint associations of house dust endotoxin and vitamin D with asthma and wheeze were examined using logistic regression adjusted for covariates in 5924 US participants of the National Health and Nutrition Examination Survey (NHANES). Interactions were assessed on the multiplicative as well as additive scale using the relative excess risk, the attributable portion due to additive interaction, and the synergy index.

RESULTS

The median endotoxin concentration was 19.1 EU/mg. Prevalence of vitamin D inadequacy (20-30 ng/ml) and deficiency (<20 ng/ml) were respectively 42.9 and 33.4%. The combination of high endotoxin and low vitamin D was associated with current asthma (OR: 1.56, 95% CI: 1.09, 2.23), wheeze in the past 12 months (OR: 1.72, 95% CI: 1.10, 3.71), recurrent wheeze (OR: 1.97, 95% CI: 1.00, 4.00), asthma diagnosis or recurrent wheeze (OR: 1.88, 95% CI: 1.33, 2.66), and current asthma or recurrent wheeze (OR:1.81, 95% CI: 1.23, 2.68) when compared to low endotoxin and normal vitamin D. The interactions between the exposures were not significant on the multiplicative or additive scale for any of the outcomes.

CONCLUSIONS

Combination of high endotoxin exposure and low vitamin D increases the odds of asthma and wheeze, but the exposures do not interact or modify each other's effect in the NHANES cohort.

1,25D3 prevents CD8(+)Tc2 skewing and asthma development through VDR binding changes to the Cyp11a1 promoter

Effector CD8⁺ T cells convert from IFN-γ⁺ (Tc1) to IL-13⁺ (Tc2) cells in the presence of IL-4. Underlying regulatory mechanisms are not fully defined. Here, we show that addition of 1,25D3, the active form of vitamin D3, during CD8⁺ T-cell differentiation prevents IL-4-induced conversion to IL-13-producers. Transfer of 1,25D3-treated CD8⁺ T cells into sensitized and challenged CD8⁺-deficient recipients fails to restore development of lung allergic responses. 1,25D3 alters vitamin D receptor (VDR) recruitment to the Cyp11a1 promoter in vitro and in vivo in the presence of IL-4. As a result, protein levels and enzymatic activity of CYP11A1, a steroidogenic enzyme regulating CD8⁺ T-cell conversion, are decreased. An epistatic effect between CYP11A1 and VDR polymorphisms may contribute to the predisposition to childhood asthma. These data identify a role for 1,25D3 in the molecular programming of CD8⁺ T-cell conversion to an IL-13-secreting phenotype through regulation of steroidogenesis, potentially governing asthma susceptibility.

Type 2 CD8⁺ T cells (Tc2) play a role in the development of experimental asthma. Here the authors show that 1,25D3, the active form of vitamin D3, can prevent conversion of CD8⁺T cells to a Tc2 phenotype, reducing asthma susceptibility.

25-hydroxy vitamin D levels are associated with childhood asthma in a population-based study in Peru

BACKGROUND

Vitamin D deficiency may be associated with an increased risk of asthma.

OBJECTIVE

We studied the association between 25-hydroxy (25-OH) vitamin D deficiency and asthma prevalence in two Peruvian populations close to the equator but with disparate degrees of urbanization.

METHODS

We conducted a population-based study in 1441 children in two communities in Peru, of which 1134 (79%) provided a blood sample for 25-OH vitamin D analysis.

RESULTS

In these 1134 children, mean age was 14.8 years; 52% were boys; asthma and atopy prevalence was 12% in Lima vs. 3% in Tumbes (P < 0.001) and 59% in Lima vs. 41% in Tumbes (P < 0.001), respectively; and, mean 25-OH vitamin D level was 20.8 ng/mL in Lima vs. 30.1 ng/mL in Tumbes (P < 0.001). Prevalence of 25-OH vitamin D deficiency (< 20 ng/mL) was 47% in Lima vs. 7% in Tumbes (P < 0.001). In multi-variable logistic regression, we found that lower 25-OH vitamin D levels were associated with an increased odds of asthma (OR = 1.7 per each 10 ng/mL decrease in 25-OH vitamin D levels, 95% CI 1.2-2.6; P < 0.01). In stratified analyses, the association between lower 25-OH vitamin D levels and asthma was limited to children with atopy (OR = 2.2, 95% CI 1.3-3.6) and not in those without atopy (OR = 0.9, 95% CI 0.5-2.0). We did not find associations between 25-OH vitamin D levels and other clinical biomarkers for asthma, including exhaled nitric oxide, total serum IgE and pulmonary function.

CONCLUSION AND CLINICAL RELEVANCE

Both asthma and 25-OH vitamin D deficiency were common among children living in Lima (latitude = 12.0 °S) but not among those in Tumbes (3.6 °S). The relationship between 25-OH vitamin D deficiency and asthma was similar in both sites and was limited among children with atopy. Future supplementation trials may need to consider stratification by atopy at the time of design.

Vitamin D Supplementation for Childhood Asthma: A Systematic Review and Meta-Analysis

Importance

There is growing evidence that vitamin D plays a role in the pathogenesis of asthma but it is unclear whether supplementation during childhood may improve asthma outcomes.

Objectives

The objective of this systematic review and meta-analysis was to evaluate the efficacy and safety of vitamin D supplementation as a treatment or adjunct treatment for asthma.

Data Sources

We searched MEDLINE, Embase, CENTRAL, and CINAHL through July 2014.

Study Selection

We included RCTs that evaluated vitamin D supplementation in children versus active control or placebo for asthma.

Data Extraction and Synthesis

One reviewer extracted data and one reviewer verified data accuracy. We qualitatively summarized the main results of efficacy and safety and meta-analyzed data on comparable outcomes across studies. We used GRADE for strength of evidence.

Main Outcome Measures

Main planned outcomes measures were ED visits and hospitalizations. As secondary outcomes, we examined measures of asthma control, including frequency of asthma exacerbations, asthma symptom scores, measures of lung function, β₂-agonist use and daily steroid use, adverse events and 25-hydroxyvitamin D levels.

Results

Eight RCTs (one parallel, one crossover design) comprising 573 children aged 3 to 18 years were included. One study (moderate-quality, n = 100) reported significantly less ED visits for children treated with vitamin D. No other studies examined the primary outcome (ED visits and hospitalizations). There was a reduced risk of asthma exacerbations in children receiving vitamin D (low-quality; RR 0.41, 95% CI 0.27 to 0.63, 3 studies, n = 378). There was no significant effect for asthma symptom scores and lung function. The serum 25(OH)D level was higher in the vitamin D group at the end of the intervention (low-quality; MD 19.66 nmol/L, 95% CI 5.96 nmol/L to 33.37 nmol/L, 5 studies, n = 167).

Limitations

We identified a high degree of clinical diversity (interventions and outcomes) and methodological heterogeneity (sample size and risk of bias) in included trials.

Conclusions and Relevance

Randomized controlled trials provide some low-quality evidence to support vitamin D supplementation for the reduction of asthma exacerbations. Evidence on the benefits of vitamin D supplementation for other asthma-related outcomes in children is either limited or inconclusive. We recommend that future trials focus on patient-relevant outcomes that are comparable across studies, including standardized definitions of asthma exacerbations.

Effectiveness of vitamin D3 in severe persistent asthmatic patients: A double blind, randomized, clinical study

Objective:

To assess the pulmonary function and quality of life in asthma patients receiving vitamin D₃ supplementation with inhaled budesonide and formoterol.

Materials and Methods:

This was a double blinded, randomized, comparative study. Patients were recruited as per the study criteria and randomized into two groups: usual care group (n = 69) patients received budesonide (800 μg) with formoterol (24 μg) and intervention care group (n = 72) patients received vitamin D₃ (1000 IU) supplementation along with budesonide (800 μg) plus formoterol (24 μg) for a period of 6 months.

Results:

A total of 140 patients completed the study. Significant within-group improvement and non-significant between-group improvement is observed with respect to FEV₁. In terms of health-related quality of life, within-group comparison revealed a significant (P < 0.05) improvement in all the domains of SGRQ. However, between-group comparisons showed statistically significant (P < 0.05) improvement in symptom, impact and total scores.

Conclusion:

On the basis of our findings, we conclude that supplementation of vitamin D₃ is effective in improving the quality of life rather than pulmonary function in severe asthmatics. However, further studies are warranted to substantiate the present findings.

Association between vitamin D levels and allergy-related outcomes vary by race and other factors

BACKGROUND

Allergy-related studies that include biological measurements of vitamin D preceding well-measured outcomes are needed.

OBJECTIVE

We sought to examine the associations between early-life vitamin D levels and the development of allergy-related outcomes in the racially diverse Wayne County Health, Environment, Allergy, and Asthma Longitudinal Study birth cohort.

METHODS

25-Hydroxyvitamin D (25[OH]D) levels were measured in stored blood samples from pregnancy, cord blood, and age 2 years. Logistic regression models were used to calculate odds ratios (ORs) with 95% CIs for a 5 ng/mL increase in 25(OH)D levels for the following outcomes at age 2 years: eczema, skin prick tests (SPTs), increased allergen-specific IgE level (≥ 0.35 IU/mL), and doctor's diagnosis of asthma (3-6 years).

RESULTS

Prenatal 25(OH)D levels were inversely associated with eczema (OR, 0.85; 95% CI, 0.75-0.96). The association was stronger in white children (white children: OR, 0.79; 95% CI, 0.57-1.09; black children: OR, 0.96; 95% CI, 0.82-1.12), although this was not statistically significant. Cord blood 25(OH)D levels were inversely associated with having 1 or more positive SPT responses and aeroallergen sensitization. Both associations were statistically significant in white children (positive SPT response: OR, 0.50; 95% CI, 0.32-0.80; ≥ 1 aeroallergen sensitization: OR, 0.50; 95% CI, 0.28-0.92) in contrast with black children (positive SPT response: OR, 0.88; 95% CI, 0.68-1.14; ≥ 1 aeroallergen sensitization: OR, 0.85; 95% CI, 0.65-1.11). 25(OH)D levels measured concurrently with outcome assessment were inversely associated with aeroallergen sensitization (OR, 0.79; 95% CI, 0.66-0.96) only among black children (white children: OR, 1.21; 95% CI, 0.87-1.69).

CONCLUSIONS

Prenatal and cord blood 25(OH)D levels were associated with some allergy-related outcomes, with a general pattern indicating that children with higher 25(OH)D levels tend to have fewer allergy-related outcomes.

Vitamin D exposure during pregnancy, but not early childhood, is associated with risk of childhood wheezing

The association between vitamin D and wheezing in early childhood is unclear. The primary objective of this study was to evaluate the association between vitamin D exposure, during both pregnancy and childhood, and early childhood wheezing. Secondary objectives were to evaluate the associations between vitamin D exposures and asthma and wheezing severity. We conducted a cohort study of children (0-5 years) recruited from 2008 to 2013 through the TARGet Kids! primary-care research network. Vitamin D exposures included maternal vitamin D supplement use during pregnancy, child vitamin D supplementation and children's 25-hydroxyvitamin D (25(OH)D) concentrations. The outcomes measured were parent-reported childhood wheezing, diagnosed asthma and wheezing severity. Vitamin D supplement and wheezing data were available for 2478 children, and blood samples were available for 1275 children. Adjusted odds ratios (aOR) were estimated using logistic regression adjusted for age, sex, ethnicity, body mass index, birth weight, outdoor play, breastfeeding duration, daycare status, parental smoking and family history of asthma. Vitamin D supplementation during pregnancy was associated with lower odds of childhood wheezing (aOR=0.65; 95% CI: 0.46-0.93). In early childhood, neither 25(OH)D (aOR per 10 nmol/l=1.01; 95% CI: 0.96-1.06) nor vitamin D supplementation (aOR=1.00; 95% CI: 0.81-1.23) was associated with wheezing. No significant associations were observed with diagnosed asthma or wheezing severity. Vitamin D supplementation during pregnancy was associated with reduced odds of wheezing, but child vitamin D supplementation and childhood 25(OH)D were not associated with reduced wheezing. The timing of exposure may be important in understanding the association between vitamin D and childhood wheezing.

No association between allergy and current 25-hydroxy vitamin D in serum or vitamin D intake

AIM

Vitamin D may be involved in allergy development, but there is conflicting evidence. We investigated if dietary intake of vitamin D and levels of 25OHD in serum differed between allergic and nonallergic adolescents and if serum 25OHD correlated with dietary intake of vitamin D or season of blood sampling.

METHODS

Serum 25-hydroxy vitamin D (25OHD) levels were analysed in 13-year-old subjects with atopic eczema (n = 55), respiratory allergy (n = 55) or no allergy (n = 55). Intake of fat-containing foods was assessed by food-frequency questionnaires, and total daily vitamin D intake was calculated. Logistic regression was used to adjust for gender, parental allergy and time of blood sampling.

RESULTS

Subjects with atopic eczema or respiratory allergy did not differ from nonallergic controls regarding serum 25OHD levels or calculated vitamin D intake. Subjects sampled in the autumn had significantly higher levels of serum 25OHD than subjects sampled in the winter or spring. Serum 25OHD levels correlated to consumption of vitamin D-fortified lean milk (p = 0.001).

CONCLUSION

The findings suggest no association between allergy and 25OHD levels in serum or vitamin D intake in adolescents. Serum 25OHD levels correlated to intake of vitamin D-fortified lean milk.

The role of circulating 25 hydroxyvitamin D in asthma: a systematic review

Asthma is a major public health issue. The co-occurrence of the high prevalence of asthma and vitamin D deficiency documented globally in recent decades has prompted several investigations into a possible association between the two conditions. The objective of this paper was to synthesize the evidence from studies that have measured the association between serum vitamin D and asthma incidence, prevalence, severity and exacerbations. A systematic search of the literature was performed in PubMed, and the available evidence was summarized both qualitatively and by meta-analysis. Only English language, observational studies measuring serum levels of 25(OH)D as the exposure were included, as this is the most robust measure of vitamin D levels. The search identified 23 manuscripts: two case-control, 12 cohort and nine cross-sectional studies. Collectively, the evidence suggests that higher serum levels of 25(OH)D are associated with a reduced risk of asthma exacerbations, but there was little evidence to suggest an association with asthma incidence, prevalence or severity. A significant amount of heterogeneity between study methodology and results restricted the scope for meta-analysis. These results suggest that vitamin D supplementation may be effective for the prevention of asthma exacerbations, but the findings need to be confirmed by clinical trials.

Vitamin D as an adjunctive therapy in asthma. Part 2: A review of human studies

Vitamin D deficiency (VDD) is highly prevalent worldwide, with adverse effects on bone health but also potentially other unfavorable consequences. VDD and asthma-incidence/severity share many common risk factors, including winter season, industrialization, poor diet, obesity, dark skin pigmentation, and high latitude. Multiple anatomical areas relevant to asthma contain both the enzyme responsible for producing activated vitamin D and the vitamin D receptor suggesting that activated vitamin D (1,25-dihydroxyvitamin D) may have important local effects at these sites. Emerging evidence suggests that VDD is associated with increased airway hyperresponsiveness, decreased pulmonary function, worse asthma control, and possibly decreased response to standard anti-asthma therapy. However the effect is inconsistent with preliminary evidence from different studies suggesting vitamin D is both beneficial and detrimental to asthma genesis and severity. Current evidence suggests that supplementation with moderate doses of vitamin D may be appropriate for maintenance of bone health in asthmatics, particularly steroid users. However emerging data from an increasing number of randomized, controlled, intervention studies of vitamin D supplementation in pediatric and adult asthma are becoming available and should help determine the importance, if any of vitamin D for asthma pathogenesis. The purpose of this second of a two-part review is to review the current human literature on vitamin D and asthma, discussing the possible consequences of VDD for asthma and the potential for vitamin D repletion as adjunct therapy.

Effect of vitamin D3 on mild to moderate persistent asthmatic patients: A randomized controlled pilot study

Background:

Asthma is a common chronic inflammatory disease of the bronchial airways. Well defined treatment options for asthma are very few. The role of vitamin D₃ on asthma is still baffling. Aim: We have examined the effect of vitamin D₃ supplementation in mild to moderate persistent asthma patients.

Materials and Methods:

We conducted an open labeled, randomized comparative trial in 48 asthma patients. The study duration was about 90 days. The study had a run-in-period of 2 weeks. At the end of run-in-period, patients were divided into two groups: Usual care group (n = 31) patients received budesonide and formoterol and intervention care group (n = 32) patients received vitamin D₃ supplementation along with their regular medicine.

Results:

The primary outcome of the study was to measure the improvement in forced expiratory volume in 1 second (FEV₁). Patients in both groups had a significant improvement in FEV₁ at the end of the study. The mean difference in percentage predicted FEV₁ in usual care and intervention care group was 4.95 and 7.07 respectively.

Conclusion:

The study concluded that adjunctive therapy of vitamin D₃ is effective in asthma patients. The present study will be an evidence based report; however, future studies are warranted in longer duration of time to substantiate the present findings.

Clinical effects of vitamin D in children with asthma

OBJECTIVE

Both asthma and vitamin D deficiency are common among children. The results from studies examining the relationship between them are contradictory. The aim of this study is to determine the relationship between the clinical parameters of asthma and vitamin D status in children.

METHODS

One hundred and twenty children diagnosed with asthma and followed-up in our hospital were included in the study. The control group included 74 children with no evidence of allergic disease. The eosinophil counts, IgE levels and serum 25 OH cholecalciferol [25(OH)D] levels were measured.

RESULTS

The patient group consisted of 73 (60.8%) males and 47 (39.2%) females with a mean age of 4.4 ± 1.2 years. There was no significant difference between the patient and control groups with respect to gender and age. The mean 25(OH)D level was 21.49 ± 7.74 ng/ml in the study group and 23.94 ± 8.97 ng/ml in the control group, and this difference was not significant (p = 0.094). The patients with asthma were grouped according to their vitamin D status as 'deficient' (group 1), 'insufficient' (group 2) and 'normal' (group 3). The sociodemographic features, duration of illness, number of hospitalizations, number of sensitivities to allergens, eosinophil count and serum IgE levels were not found to be different between the groups. However, the total number of exacerbations, asthma severity and systemic glucocorticoid need in the previous year were significantly higher in the deficiency group (p < 0.05).

CONCLUSION

Vitamin D levels were not significantly different in patients with asthma. Vitamin D deficiency was common in the study group as well as in the control group. The clinical severity of disease, the number of exacerbations and the systemic glucocorticoid need were related to vitamin D level.

Vitamin D and asthma-life after VIDA?

The vitamin D hypothesis postulates that lower vitamin D levels are causally associated with increased asthma risk and asthma severity. Multiple epidemiological studies have shown an inverse relationship between circulating vitamin D levels (in the form of 25-hydroxy vitamin D) and asthma severity and control and lung function. However, in the recently published vitamin D and asthma (VIDA) study, vitamin D supplementation failed to show an improvement in asthma control in adults. This article reviews the current epidemiological and trial evidence for vitamin D and asthma and explores some of the possible alternative explanations for previous findings (including "reverse causation" and the importance of studying children and adults). We also address some of the unique challenges of conducting vitamin D trials and potential ways to address them. Finally, I will argue for further clinical trials of vitamin D in asthma, especially in children, using knowledge gained from the VIDA trial.

A mutated vitamin D receptor in hereditary vitamin D-resistant rickets prevents induction of bronchial hyperreactivity and inflammation

CONTEXT

Previous studies have reported an association between vitamin D deficiency and asthma. Hereditary 1,25-dihydroxyvitamin D-resistant rickets (HVDRR) patients provide a natural model to assess the role of the vitamin D receptor (VDR) in regulating human lung immune responses and airway hyperreactivity.

OBJECTIVES

The aim of the study was to determine the role of the VDR on lung functions, airways, and systemic markers of inflammation and allergy in HVDRR patients.

DESIGN AND METHODS

Thirteen HVDRR patients (aged 6-37 y) and 17 normal controls (aged 6-38 y) underwent spirometry, a methacholine challenge test (MCT), blood tests, allergy skin tests, determination of fractional exhaled nitric oxide, and measurement of serum and exhaled breath condensate cytokines, including IL-4, IL-5, IL-10, IL-17, and interferon-γ levels.

RESULTS

All HVDRR patients had negative MCT results, whereas six controls (35.3%) had positive MCT results (P < .014). Serum IgE levels, eosinophil counts, and fractional exhaled nitric oxide and allergy skin test results were similar for the HVDRR patients and controls, as were the serum cytokine concentrations. The HVDRR patients had different cytokine levels in their exhaled breath condensate (increased IL-4 and IL-17 and decreased IL-5, IL-10, and interferon-γ levels) compared to the controls (P < .005).

CONCLUSIONS

HVDRR patients show diverse exhaled cytokine profiles but seem to be protected against provoked bronchial hyperreactivity and clinical asthma. These findings suggest that an intact VDR has an important role in asthma pathophysiology.

Vitamin D in inflammatory diseases

Changes in vitamin D serum levels have been associated with inflammatory diseases, such as inflammatory bowel disease (IBD), rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis (MS), atherosclerosis, or asthma. Genome- and transcriptome-wide studies indicate that vitamin D signaling modulates many inflammatory responses on several levels. This includes (i) the regulation of the expression of genes which generate pro-inflammatory mediators, such as cyclooxygenases or 5-lipoxygenase, (ii) the interference with transcription factors, such as NF-κB, which regulate the expression of inflammatory genes and (iii) the activation of signaling cascades, such as MAP kinases which mediate inflammatory responses. Vitamin D targets various tissues and cell types, a number of which belong to the immune system, such as monocytes/macrophages, dendritic cells (DCs) as well as B- and T cells, leading to individual responses of each cell type. One hallmark of these specific vitamin D effects is the cell-type specific regulation of genes involved in the regulation of inflammatory processes and the interplay between vitamin D signaling and other signaling cascades involved in inflammation. An important task in the near future will be the elucidation of the regulatory mechanisms that are involved in the regulation of inflammatory responses by vitamin D on the molecular level by the use of techniques such as chromatin immunoprecipitation (ChIP), ChIP-seq, and FAIRE-seq.

Association between low vitamin D levels and the diagnosis of asthma in children: a systematic review of cohort studies

BACKGROUND

There is conflicting evidence about the association between low vitamin D levels in children and development of asthma in later life. The objective of this study was to systematically review the evidence for an epidemiological association between low serum levels of vitamin D and the diagnosis of asthma in children.

METHODS

We used the Cochrane methodology for conducting systematic reviews. The search strategy included an electronic search of MEDLINE and EMBASE in February 2013. Two reviewers completed, in duplicate and independently, study selection, data abstraction, and assessment of risk of bias.

RESULTS

Of 1081 identified citations, three cohort studies met eligibility criteria. Two studies found that low serum vitamin D level is associated with an increased risk of developing asthma late in childhood, while the third study found no association with either vitamin D2 or vitamin D3 levels. All three studies suffer from major methodological shortcomings that limit our confidence in their results.

CONCLUSIONS

Available epidemiological evidence suggests a potential association between low serum levels of vitamin D and the diagnosis of asthma in children. High quality studies are needed to reliably answer the question of interest.

Effect of vitamin D-binding protein genotype on the development of asthma in children

BACKGROUND

Potential vitamin D-related influences on inflammatory diseases such as asthma are controversial, including the suggestion that vitamin D insufficiency is associated with increased asthma morbidity. Vitamin D-binding protein transports vitamin D metabolites in the circulation. Single nucleotide polymorphisms in the GC gene encoding vitamin D-binding protein are associated with circulating vitamin D metabolite levels in healthy infants and toddlers.

OBJECTIVE

To test the hypothesis that GC single nucleotide polymorphisms encoding the D432E and T436K variants predict subsequent development of asthma in healthy children.

METHODS

A retrospective medical record review was performed to determine the development of asthma in 776 children in whom GC genotype, vitamin D-binding protein concentration, and circulating 25-hydroxyvitamin D had been determined at 6 to 36 months of age. Demographic and detailed current clinical data were collected and criteria for asthma were recorded.

RESULTS

GC genotype was available for 463 subjects. After an initial analysis of all subject data, the analysis was limited to the predominant Hispanic population (72.1%) to minimize potential confounding effects of ethnicity. Asthma was diagnosed in 87 children (26%). Subjects with the GC genotype encoding the ET/ET (Gc1s/Gc1s) variant had lower odds of developing asthma, representing a protective effect compared with subjects with the DT/DT (Gc1f/Gc1f) variant.

CONCLUSION

In the Hispanic population of inner-city New Haven, Connecticut, the ET/ET (Gc1s/Gc1s) genotype of vitamin D-binding protein might confer protection against the development of asthma compared with the wild-type genotype DT/DT (Gc1f/Gc1f).

Immunoregulatory mechanisms of vitamin D relevant to respiratory health and asthma

Vitamin D deficiency is prevalent among people with various immune-mediated conditions, including autoimmune diseases and asthma. Serum 25(OH)D levels inversely correlate with asthma severity, glucocorticoid responsiveness/dosage, and markers of pathogenesis, such as airway remodeling, IgE, and eosinophilia. Trials involving supplementation with active vitamin D or a precursor are beginning to emerge with variable results that, in part, reflect differences in study design. This review looks at the mechanisms by which vitamin D may protect against asthma, including increasing glucocorticoid responsiveness, skewing immune cells towards a regulatory phenotype, reducing the incidence of infections, airway remodeling, eosinophilia, and lowering the levels of IgE. Also discussed is the therapeutic potential for vitamin D, which is likely to be applicable to immune-mediated conditions beyond simply asthma.