Vitamin D deficiency causes deficits in lung function and alters lung structure

Prenatal vitamin d supplementation and child respiratory health: a randomised controlled trial

BACKGROUND

Observational studies suggest high prenatal vitamin D intake may be associated with reduced childhood wheezing. We examined the effect of prenatal vitamin D on childhood wheezing in an interventional study.

METHODS

We randomised 180 pregnant women at 27 weeks gestation to either no vitamin D, 800 IU ergocalciferol daily until delivery or single oral bolus of 200,000 IU cholecalciferol, in an ethnically stratified, randomised controlled trial. Supplementation improved but did not optimise vitamin D status. Researchers blind to allocation assessed offspring at 3 years. Primary outcome was any history of wheeze assessed by validated questionnaire. Secondary outcomes included atopy, respiratory infection, impulse oscillometry and exhaled nitric oxide. Primary analyses used logistic and linear regression.

RESULTS

We evaluated 158 of 180 (88%) offspring at age 3 years for the primary outcome. Atopy was assessed by skin test for 95 children (53%), serum IgE for 86 (48%), exhaled nitric oxide for 62 (34%) and impulse oscillometry of acceptable quality for 51 (28%). We found no difference between supplemented and control groups in risk of wheeze [no vitamin D: 14/50 (28%); any vitamin D: 26/108 (24%) (risk ratio 0.86; 95% confidence interval 0.49, 1.50; P = 0.69)]. There was no significant difference in atopy, eczema risk, lung function or exhaled nitric oxide between supplemented groups and controls.

CONCLUSION

Prenatal vitamin D supplementation in late pregnancy that had a modest effect on cord blood vitamin D level, was not associated with decreased wheezing in offspring at age three years.

TRIAL REGISTRATION

Controlled-Trials.com ISRCTN68645785.

Modeling the influence of vitamin D deficiency on cigarette smoke-induced emphysema

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide. While the primary risk factor for COPD is cigarette smoke exposure, vitamin D deficiency has been epidemiologically implicated as a factor in the progressive development of COPD-associated emphysema. Because of difficulties inherent to studies involving multiple risk factors in the progression of COPD in humans, we developed a murine model in which to study the separate and combined effects of vitamin D deficiency and cigarette smoke exposure. During a 16-week period, mice were exposed to one of four conditions, control diet breathing room air (CD-NS), control diet with cigarette smoke exposure (CD-CSE), vitamin D deficient diet breathing room air (VDD-NS) or vitamin D deficient diet with cigarette smoke exposure (VDD-CSE). At the end of the exposure period, the lungs were examined by a pathologist and separately by morphometric analysis. In parallel experiments, mice were anesthetized for pulmonary function testing followed by sacrifice and analysis. Emphysema (determined by an increase in alveolar mean linear intercept length) was more severe in the VDD-CSE mice compared to control animals and animals exposed to VDD or CSE alone. The VDD-CSE and the CD-CSE mice had increased total lung capacity and increased static lung compliance. There was also a significant increase in the matrix metalloproteinase-9: tissue inhibitor of metalloproteinases-1 (TIMP-1) ratio in VDD-CSE mice compared with all controls. Alpha-1 antitrypsin (A1AT) expression was reduced in VDD-CSE mice as well. In summary, vitamin D deficiency, when combined with cigarette smoke exposure, seemed to accelerate the appearance of emphysemas, perhaps by virtue of an increased protease-antiprotease ratio in the combined VDD-CSE animals. These results support the value of our mouse model in the study of COPD.

Early life influences on the development of chronic obstructive pulmonary disease

There is increasing evidence that chronic obstructive pulmonary disease (COPD) is not simply a disease of old age that is largely restricted to heavy smokers, but may be associated with insults to the developing lung during foetal life and the first few years of postnatal life, when lung growth and development are rapid. A better understanding of the long-term effects of early life factors, such as intrauterine growth restriction, prenatal and postnatal exposure to tobacco smoke and other pollutants, preterm delivery and childhood respiratory illnesses, on the subsequent development of chronic respiratory disease is imperative if appropriate preventive and management strategies to reduce the burden of COPD are to be developed. The extent to which insults to the developing lung are associated with increased risk of COPD in later life depends on the underlying cause, timing and severity of such derangements. Suboptimal conditions in utero result in aberrations of lung development such that affected individuals are born with reduced lung function, which tends to remain diminished throughout life, thereby increasing the risk both of wheezing disorders during childhood and subsequent COPD in genetically susceptible individuals. If the current trend towards the ever-increasing incidence of COPD is to be reversed, it is essential to minimize risks to the developing lung by improvements in antenatal and neonatal care, and to reduce prenatal and postnatal exposures to environmental pollutants, including passive tobacco smoke. Furthermore, adult physicians need to recognize that lung disease is potentially associated with early life insults and provide better education regarding diet, exercise and avoidance of smoking to preserve precious reserves of lung function in susceptible adults. This review focuses on factors that adversely influence lung development in utero and during the first 5 years of life, thereby predisposing to subsequent COPD.

Effects of vitamin D on immune disorders with special regard to asthma, COPD and autoimmune diseases: a short review

This paper reviews the recent data on the role of vitamin D (VD) in the genesis of various immunological disorders. It inhibits immune reactions in general, but it enhances the transcription of 'endogenous antibiotics' such as cathelicidin and defensins. VD inhibits the genesis of both Th1- and Th2-cell mediated diseases. The pleiotropic character VD-induced effects are due to the altered transcription of hundreds of genes. VD supplementation in most related studies reduced the prevalence of asthma. Th1-dependent autoimmune diseases (e.g., multiple sclerosis, Type 1 diabetes, Crohn's disease, rheumatoid arthritis and so on) are also inhibited by VD due to inhibition of antigen presentation, reduced polarization of Th0 cells to Th1 cells and reduced production of cytokines from the latter cells. VD seems to also be a useful adjunct in the prevention of allograft rejection. Last but not least, VD supplementation may be useful in the prevention or adjunct treatment of chronic obstructive pulmonary disease.

The current state of play of rodent models to study the role of vitamin D in UV-induced immunomodulation

Ultraviolet radiation (UVR) from sunlight is immunomodulatory and the main source of vitamin D for humans. Vitamin D can also regulate adaptive immunity, through mechanisms that involve the induction or activation of regulatory T cells. Similar mechanisms have also been proposed for the induction of regulatory T cells after skin exposure to UVR. Here we discuss the converging and diverging immunoregulatory pathways of UVR and vitamin D, including the molecular pathways for regulatory T cell induction, non-genomic pathways regulated by vitamin D, antimicrobial peptides, skin integrity and potential interactions between vitamin D and other UVR-induced mediators. We then discuss possible in vivo approaches that could be used to demonstrate a direct (or otherwise) role for vitamin D in mediating the immunosuppressive effects of UVR such as the use of dietary vitamin D restriction to induce vitamin D deficiency, gene knockout mice or drugs to block enzymes of vitamin D metabolism. We end with discussion of the epigenetic effects of vitamin D and UVR for immunosuppression.

Vitamin D status is associated with bone mineral density and functional exercise capacity in patients with chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is associated with several extrapulmonary effects that contribute to the severity of the disease. Vitamin D is suggested to play a role in COPD and its related extrapulmonary effects.

AIMS

To determine the prevalence of vitamin D deficiency and its relation with bone density, muscle strength, and exercise capacity in patients with COPD.

METHODS

Our cross-sectional study included patients with moderate to very severe COPD. We collected data on lung function, body composition, bone density, quadriceps muscle strength, 6-minute walking distance, and plasma 25-hydroxyvitamin D (25(OH)D) concentration. Vitamin D deficiency was defined as plasma 25(OH)D concentration below 50 nmol/L.

RESULTS

In total, 151 COPD patients were included; 87 patients (58%) had vitamin D deficiency. Plasma 25(OH)D concentration was positively associated with bone density (P = 0.005) and 6-minute walking distance (P < 0.001) after adjustment for potential confounders. Plasma 25(OH)D concentration was not associated with quadriceps muscle strength.

CONCLUSIONS

The majority of COPD patients had vitamin D deficiency. Plasma 25(OH)D concentration was positively associated with bone density and exercise capacity. Intervention studies are necessary to determine whether vitamin D supplementation is of benefit in the prevention or treatment of osteoporosis and poor exercise capacity in patients with COPD.

Vitamin D and respiratory infections in infants and toddlers: a nutri-shine perspective

There is compelling evidence of a global problem of poor vitamin D status in expecting mothers and postnatal life; and even more critical, is the evidence showing the association of vitamin D deficiency with increased morbidity and mortality risks from respiratory infections. Viral and bacterial pneumonia kills more children than any other illness, accounting for 19 % of all deaths in children less than five years of age worldwide; and under-nutrition, which includes vitamin D insufficiency/deficiency, has been implicated in 53 % of all these deaths. Poor vitamin D status is a result of insufficient sunlight exposure and/or poor dietary intake. Greater understanding of the role of vitamin D deficiency in precipitating lung infections grew from the use of rodent models and observational and intervention studies in infants and toddlers. Vitamin D adequacy is important to maintaining the key protective mechanism of developing lungs since it mediates the synthesis of antimicrobial peptides, the lungs strongest defense against viral and bacterial pathogens. If vitamin D intervention currently under study in several clinical trials is proven successful, then implementation of new fortification practices, revised guidelines for healthy sun exposure and public health programs for vitamin D supplementation of pregnant/lactating women and their infants may be effective strategies to aide in preventing neonates and children under five from developing pneumonia. Globally, there is potential to save more than a million young lives with preventive treatment, a compelling reason why the efficacy of optimizing vitamin D mediated defense against respiratory pathogens in infants and children merits further study.

Vitamin D, Vitamin D Receptor, and Tissue Barriers

Tissue barriers are critical in the pathogenesis of human diseases, such as atopic dermatitis, inflammatory bowel diseases and various cancers. Preserving or restoring barrier functions of the epithelia cells is a therapeutic strategy to prevent and treat the illness. Mounting evidence indicates that vitamin D and the vitamin D receptor (VDR) play key roles in the pathogenesis of human diseases. In particular, we note an interesting link between vitamin D/VDR signaling and tissue barriers. In the current review, we summarize the recent progress on vitamin D and cell junction complexes. We focus on the functions of VDR and VDR-associated intracellular junction proteins, such as β-catenin and claudins. We also discuss the potential therapeutic functions of vitamin D in treating defective tissue barriers that involve skin, intestine, lung, kidney and other organs. However, the mechanisms for the vitamin D/VDR signaling in tissue barriers remain largely unknown. Further studies on vitamin D/VDR’s multiple functions in physiological models will suggest new therapeutic targets for prevention and treatment diseases with defective barrier functions.

Vitamin D and asthma in children

Vitamin D deficiency and insufficiency are increasingly being recognized in the general population, and have been largely attributed to lifestyle changes (reduced exposure to sunshine due to working indoors or the use of protective clothing and sunscreen; changes in diet) over the last few decades. The musculoskeletal consequences of severe vitamin D deficiency are well established, however, a number of other disorders have now been linked to vitamin D insufficiency, including asthma. There is growing appreciation of the likely importance of vitamin D as a pleiotrophic mediator that contributes to pulmonary health. Children with asthma appear to be at increased risk of vitamin D insufficiency. Epidemiologic data suggest that low serum vitamin D in children with asthma is associated with more symptoms, exacerbations, reduced lung function, increased medication usage and severe disease. In vitro studies have demonstrated that vitamin D enhances steroid responsiveness in adult asthmatics. Vitamin D may play an important role in pulmonary health by inhibiting inflammation, in part through maintaining regulatory T cells, and direct induction of innate antimicrobial mechanisms. More research is required to fully understand the role of vitamin D in the maintenance of airway homeostasis and address the diagnostic and therapeutic implications vitamin D may have in the future of asthma management. This review summarises the current understanding and uncertainties regarding the effect of vitamin D deficiency and insufficiency in children with asthma.

Lipopolysaccharide-induced lung injury is independent of serum vitamin D concentration

Vitamin D deficiency is increasing in incidence around the world. Vitamin D, a fat-soluble vitamin, has documented effects on the innate and adaptive immune system, including macrophage and T regulatory (Treg) cell function. Since Treg cells are important in acute lung injury resolution, we hypothesized that vitamin D deficiency increases the severity of injury and delays injury resolution in lipopolysaccharide (LPS) induced acute lung injury. Vitamin D deficient mice were generated, using C57BL/6 mice, through diet modification and limited exposure to ultraviolet light. At 8 weeks of age, vitamin D deficient and sufficient mice received 2.5 g/kg of LPS or saline intratracheal. At 1 day, 3 days and 10 days, mice were anesthetized and lung elastance measured. Mice were euthanized and bronchoalveolar lavage fluid, lungs and serum were collected. Ex vivo neutrophil chemotaxis was evaluated, using neutrophils from vitamin D sufficient and deficient mice exposed to the chemoattractants, KC/CXCL1 and C5a, and to bronchoalveolar lavage fluid from LPS-exposed mice. We found no difference in the degree of lung injury. Leukocytes were mildly decreased in the bronchoalveolar fluid of vitamin D deficient mice at 1 day. Ex-vivo, neutrophils from vitamin D deficient mice showed impaired chemotaxis to KC but not to C5a. Vitamin D deficiency modestly impairs neutrophil chemotaxis; however, it does not affect lung injury or its resolution in an LPS model of acute lung injury.

1,25-Dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) attenuates airway remodeling in a murine model of chronic asthma

OBJECTIVES

1,25-Dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) has immune- and inflammation-modulating properties in asthma, but its possible effects on asthmatic airway remodeling remain uncertain. In this study, we investigated the effects of 1,25-(OH)(2)D(3) on airway remodeling in a murine model of chronic asthma and investigated its role in regulating nuclear factor-κB (NF-κB) activation.

METHODS

BALB/c mice were sensitized to ovalbumin (OVA) and subsequently exposed to intranasal OVA challenges for 9 weeks. Some mice also received an intraperitoneal injection of 1,25-(OH)(2)D(3) at the time of challenge. At the end of the challenge period, mice were evaluated for chronic airway inflammation and airway remodeling. Nuclear translocation of NF-κB p65 in lung tissue was examined by Western blot. Inhibitor of NF-κB alpha (IκBα) expression was determined by real-time quantitative Reverse Transcription Polymerase Chain Reaction (RT-PCR) and Western blot. Phosphorylated IκBα protein expression was also determined by Western blot.

RESULTS

1,25-(OH)(2)D(3) treatment reduced OVA-induced chronic inflammation in lung tissue and attenuated established structural changes of the airways, including subepithelial collagen deposition, goblet cell hyperplasia, and increased airway smooth muscle mass. 1,25-(OH)(2)D(3) also inhibited the nuclear translocation of NF-κB p65 in lung tissue. Concurrently, 1,25-(OH)(2)D(3) induced increased IκBα protein levels via inducing increased IκBα mRNA levels and decreased IκBα phosphorylation.

CONCLUSION

1,25-(OH)(2)D(3) could attenuate asthmatic airway remodeling and its inhibition of NF-κB activation may underlie this protective effect.

Nutritional targets to enhance exercise performance in chronic obstructive pulmonary disease

PURPOSE OF REVIEW

This review presents current knowledge regarding the rationale and efficacy of nutrition as an ergogenic aid to enhance the effects of exercise and training in chronic obstructive pulmonary disease (COPD).

RECENT FINDINGS

Altered body composition and skeletal muscle dysfunction in COPD suggest that exercise capacity can be targeted via several metabolic routes. Muscle metabolic alterations in COPD include a reduced oxidative metabolism and enhanced susceptibility for oxidative stress. Muscle wasting may be associated with deficiencies of vitamin D and low branched-chain amino acid levels. Exercise training is of established benefit in COPD but clear-cut clinical trial evidence to support the performance enhancing effect of nutritional intervention is lacking. One randomized controlled trial suggested that augmentation of training with polyunsaturated fatty acids may improve exercise capacity. Conflicting results are reported on dietary creatine supplementation in patients with COPD receiving pulmonary rehabilitation and results from acute intervention studies do not directly imply long-term effects of glutamate or glutamine supplementation as an ergogenic aid in COPD. Recent data indicate that not only muscle but also visceral fat may be an important additional target for combined nutrition and exercise intervention in COPD to improve physical performance and decrease cardiometabolic risk.

SUMMARY

There is a clear need for adequately powered and controlled intervention and maintenance trials to establish the role of nutritional supplementation in the enhancement of exercise performance and training and the wider management of the systemic features of the disease.

Maternal late-pregnancy serum 25-hydroxyvitamin D in relation to childhood wheeze and atopic outcomes

BACKGROUND

Studies exploring the relationship between prenatal vitamin D exposure and childhood asthma have yielded conflicting results. Higher vitamin D intake during pregnancy has been shown to lower the risk of childhood wheeze, yet a study of maternal late-pregnancy serum 25-hydroxyvitamin D suggested higher serum concentrations may be associated with increased childhood asthma.

OBJECTIVE

To assess the relationship between mothers' serum 25-hydroxyvitamin D status and asthma and wheeze phenotypes in their children at age 6 years. Also to explore the relationship between maternal 25-hydroxyvitamin D status and objective measures of childhood atopy and lung function.

METHODS

Serum 25-hydroxyvitamin D was measured at 34 weeks' gestation in the mothers of 860 children born at term. Wheeze was classified as either transient or persistent/late using questionnaire data collated from 6, 12, 24 and 36 months and 6 years. At 6 years spirometry was performed and atopic status was determined by skin prick testing, exhaled nitric oxide was measured in 451 children and bronchial hyperresponsiveness in 216 children.

RESULTS

There were no significant associations between maternal late-pregnancy 25-hydroxyvitamin D status and either asthma or wheeze at age 6 years. Maternal vitamin D status was not associated with transient or persistent/late wheeze; no significant association was found between persistent/late wheeze when subdivided according to atopic status. No associations were found with skin sensitisation or lung function.

CONCLUSIONS

This study provides no evidence that exposure to higher concentrations of 25-hydroxyvitamin D in maternal serum during late pregnancy increases the risk of childhood asthma, wheeze or atopy.

Vitamin D status in critically ill children

BACKGROUND

Hypovitaminosis D is an independent risk factor for cardiovascular disease, muscle weakness, impaired metabolism, immune dysfunction, and compromised lung function. Hypovitaminosis D is common in critically ill adults and has been associated with adverse outcomes. The prevalence of hypovitaminosis D and its significance in critically ill children are unclear.

METHODS

We performed a prospective study to determine the prevalence of hypovitaminosis D in 316 critically ill children, and examined its association with physiological and biochemical variables, length of pediatric intensive care unit (PICU) stay, and hospital mortality.

RESULTS

The prevalence of hypovitaminosis D [25(OH)D(3) <50 nmol/L] was 34.5 %. Hypovitaminosis D was more common in postoperative cardiac patients than in general medical ICU patients (40.5 versus 22.6 %, p = 0.002), and the cardiac patients had a higher inotrope score [2.5 (1.9-3.3) versus 1.4 (1.1-1.9), p = 0.006]. Additionally, ionized calcium within the first 24 h was lower in patients with 25(OH)D(3) <50 nmol/L [1.07 (0.99-1.14) mmol/L] compared with patients with normal vitamin D(3) [1.17 (1.14-1.19) mmol/L, p = 0.02]. Hypovitaminosis D was not associated with longer PICU stay or increased hospital mortality.

CONCLUSIONS

Hypovitaminosis D is common in critically ill children, and is associated with higher inotropes in the postoperative cardiac population, but not with PICU length of stay or hospital survival.

Vitamin D and atopy and asthma phenotypes in children

PURPOSE OF REVIEW

To give an overview of the recent research into whether a lack of vitamin D contributes to the development of atopy and asthma in childhood.

RECENT FINDINGS

I describe here the recent epidemiological studies relating vitamin D status to atopy and asthma in children, focusing on determinants of major asthma phenotypes in childhood. Recent findings include the observations that vitamin D levels are inversely associated with degree of corticosteroid use, worsening airflow limitation and increased exacerbations among asthmatics. Low vitamin D has been associated with atopy and asthma in children and adolescents in a community cohort, predominantly in boys, with vitamin D at age 6 predicting these outcomes at 14. I also detail the mechanistic studies examining relevant vitamin D-regulated processes; recent findings include the demonstration that offspring of mice with vitamin D deficiency in pregnancy show reduced lung volume and function.

SUMMARY

The current literature suggests that intervention to ensure adequate vitamin D levels during both pregnancy and childhood may reduce the development of atopy and asthma in children. However, important questions need to be answered regarding the levels of vitamin D required, which may vary between the sexes and between individuals, and the optimal timing and duration of such intervention.

Review article: vitamin D and inflammatory bowel disease--established concepts and future directions

BACKGROUND

Understanding of the role of vitamin D in health and disease has increased markedly in the past decade, with its involvement extending well beyond traditional roles in calcium and phosphate homeostasis and musculoskeletal health. This conceptual expansion has been underpinned by identification and exploration of components of this axis including vitamin D-binding protein, key enzymes and receptors in multiple cell types, and a greater recognition of nonclassical autocrine and paracrine effects. Its influence in IBD remains uncertain.

AIM

To review the role of vitamin D in bone health, immune regulation and cancer prevention in IBD, and to outline practical issues and limitations of its use.

METHODS

An extensive online literature review including PubMed and Medline.

RESULTS

In patients with IBD, the vitamin D axis provides an important and often underutilised pathway to preserving bone health. Furthermore, an exciting body of clinical and basic science research demonstrates that these pathways may have an integral part to play in regulation of the immune response in IBD, through effects on the intestinal barrier, antigen presenting cells and adaptive T cells. The possibility of chemoprevention requires further study. The optimal target level of 25-hydroxy vitamin D in patients with IBD is currently uncertain, as is the best therapeutic modality.

CONCLUSIONS

Study of vitamin D pathways may result in the development of relatively inexpensive therapeutic options to optimise patient outcomes. Further prospective clinical research is required to address efficacy and long-term safety.

The risk of all-cause mortality is inversely related to serum 25(OH)D levels

CONTEXT AND OBJECTIVES

Vitamin D plays a key role in maintaining bone health, but evidence for its nonskeletal effects is inconsistent. This study aims to examine the association between serum 25-hydroxyvitamin D [25(OH)D] levels and all-cause mortality in a large general population cohort.

DESIGN, PARTICIPANTS, AND SETTING

Using the computerized database of the largest health care provider in Israel, we identified a cohort of subjects 20 years old or older with serum 25(OH)D levels measured between January 2008 and December 2009. Vital status was ascertained through August 2011.

RESULTS

Median follow-up was 28.5 months (interquartile range 23.8-33.5 months); 7,247 of 182,152 participants (4.0%) died. Subjects who died had significantly lower serum 25(OH)D levels (mean 44.8 ± 24.2 nmol/liter) than those alive at the end of follow-up (51.0 ± 23.2 nmol/liter), P < 0.001. After adjustment for age, gender, ethnicity, and seasonality, the hazard ratio (HR) for all-cause mortality was 2.02 [95% confidence interval (CI) 1.89-2.15] for the lowest serum 25(OH)D quartile (<33.8 nmol/liter) compared with the highest. After further adjustment for comorbidity, use of vitamin D supplements and statins, smoking, socioeconomic status, and body mass index, the HR was 1.81 (95% CI 1.69-1.95). This remained, even after adjustment for serum low-density lipoprotein, high-density lipoprotein, calcium level (corrected for serum albumin levels), and glomerular filtration rate, 1.85 (95% CI 1.70-2.01). The fully adjusted HR associated with being in the second 25(OH)D quartile (33.8-49.4 nmol/liter) was 1.25 (95% CI 1.16-1.34).

CONCLUSIONS

All-cause mortality is independently and inversely associated with serum 25(OH)D levels at levels less than 50 nmol/liter.

Vitamin D deficiency as a risk factor for childhood allergic disease and asthma

PURPOSE OF REVIEW

Over the past 2 years, the number of studies relating vitamin D deficiency and asthma and allergies has increased significantly. The purpose of this review is to update the last review in this journal and examine the evidence of the relationship between vitamin D deficiency and childhood asthma and allergies.

RECENT FINDINGS

In the past 2 years since the last review, there have been many studies, both cross-sectional and prospective, that have investigated the effects of vitamin D on the inception and severity of asthma and allergies. Most, but not all, studies have shown that low vitamin D levels increase the risk for asthma and allergies, but a few suggest an increased risk with high levels. Results from small trials of short duration suggest that vitamin D supplementation decreases severity of eczema and decreases the risk for asthma exacerbations.

SUMMARY

Data that vitamin D deficiency results in increased risks for asthma and allergies continues to accumulate. However, the optimal level of vitamin D that decreases both the risk for development and severity of these disorders remains elusive. Results of ongoing clinical trials of vitamin D supplementation will be needed before recommendations can be firmly established.

Biological mechanisms for nutritional regulation of maternal health and fetal development

This review paper highlights mechanisms for nutritional regulation of maternal health and fetal development. Malnutrition (nutrient deficiencies or obesity) in pregnant women adversely affects their health by causing or exacerbating a plethora of problems, such as anaemia, maternal haemorrhage, insulin resistance, and hypertensive disorders (e.g. pre-eclampsia/eclampsia). Maternal malnutrition during gestation also impairs embryonic and fetal growth and development, resulting in deleterious outcomes, including intrauterine growth restriction (IUGR), low birthweight, preterm birth, and birth defects (e.g. neural tube defects and iodine deficiency disorders). IUGR and preterm birth contribute to high rates of neonatal morbidity and mortality. Major common mechanisms responsible for malnutrition-induced IUGR and preterm birth include: (i) abnormal growth and development of the placenta; (ii) impaired placental transfer of nutrients from mother to fetus; (iii) endocrine disorders; and (iv) disturbances in normal metabolic processes. Activation of a series of physiological responses leading to premature and sustained contraction of the uterine myometrium also results in preterm birth. Recent epidemiologic studies have suggested a link between IUGR and chronic metabolic disease in children and adults, and the effects of IUGR may be carried forward to subsequent generations through epigenetics. While advanced medical therapies, which are generally unavailable in low-income countries, are required to support preterm and IUGR infants, optimal nutrition during pregnancy may help ameliorate many of these problems. Future studies are necessary to develop effective nutritional interventions to enhance fetal growth and development and alleviate the burden of maternal morbidity and mortality in low- and middle-income countries.

The impact of vitamin D deficiency on immune T cells in asthmatic children: a case-control study

Background

Vitamin D exerts profound effects on both adaptive and innate immune functions involved in the development and course of autoimmune and inflammatory diseases. As the incidence of vitamin D insufficiency is surprisingly high in the general population, experimental studies have started to investigate whether vitamin D levels (measured as serum 25 hydroxy vitamin D-25[OH]D) are correlated with immune cells and clinical parameters.

Purpose

The aim of the present research was to investigate serum vitamin D status in a case-control study in children with asthma and to study associations between vitamin D levels and certain immunological parameters.

Materials and methods

A case control study of thirty-nine children with clinically controlled asthma was enrolled to assess the relationship between serum vitamin D concentrations and disease activity. Vitamin D was assayed with a radioimmunoassay kit. We evaluated the relationship between vitamin D concentrations and forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), and the FEV₁/FVC ratio. Correlations between inflammatory mediators, Th1, Th2, Th17, and regulatory T cells (Treg) and vitamin D were investigated.

Results

Only 15.38% of our asthmatic children had a sufficient serum 25(OH)D (≥30 ng/mL) whereas 80% of healthy children expressed sufficient levels. Deficient values of vitamin D (<20 ng/mL) were observed in 17 (43.59%) asthmatic patients (14.40 ± 3.30 ng/mL; P = 0.0001). Deficiency was not observed in controls. Th1/Th2 ratio was significantly correlated to 25(OH) D level (r = 0.698; P = 0.0001). A significant negative correlation was observed between serum interleukin-17 and vitamin D levels in young asthmatics (r = −0.617; P = 0.001). A significant correlation was observed between CD25⁺Foxp3⁺ Treg cells and vitamin D values in asthmatics (r = 0.368; P = 0.021).

Conclusion

Even in a southern Mediterranean country, hypovitaminosis D is frequent in children with asthma. Our findings suggest that vitamin D is an important promoter of T cell regulation in vivo in young asthmatics.

A nationwide cohort study of the risk of chronic obstructive pulmonary disease in coeliac disease

OBJECTIVE

Chronic obstructive pulmonary disease (COPD) continues to be an important cause of morbidity, mortality and healthcare costs in the western world. Although smoking is an important trigger of COPD, other factors such as chronic inflammation and malnutrition are known to influence its development. Because coeliac disease (CD) is characterized both by dysregulated inflammation and malnutrition, the possibility of an association between CD and COPD was investigated.

METHODS

Through biopsy data from all Swedish pathology departments, we identified 10 990 individuals with CD who were biopsied between 1987 and 2008 (Marsh 3: villous atrophy). As controls, 54 129 reference individuals matched for age, sex, county and calendar year of first biopsy were selected. Cox regression analysis was then performed to estimate hazard ratios (HRs) for having a diagnosis of COPD according to the Swedish Patient Register.

RESULTS

During follow-up, 380 individuals with CD (3.5%) and 1391 (2.6%) controls had an incident diagnosis of COPD, which corresponds to an HR of 1.24 (95% CI: 1.10-1.38) and an excess risk of COPD of 79/100 000 person-years in CD. The risk increase remained 5 years after biopsy (HR = 1.17; 95% CI: 1.00-1.37). Risk estimates did not change with adjustment for type 1 diabetes, thyroid disease, rheumatoid arthritis, country of birth or level of education. Men with CD were at a higher risk of COPD (HR = 1.39; 95% CI: 1.18-1.62) than women with CD (HR = 1.11; 95% CI: 0.94-1.30). Of note, CD was also associated with COPD before CD diagnosis (odds ratio = 1.22; 95% CI: 1.02-1.46). Conclusion.  Patients with CD seem to be at a moderately increased risk of COPD both before and after CD diagnosis.

Calcitriol decreases expression of importin α3 and attenuates RelA translocation in human bronchial smooth muscle cells

PURPOSE

A potent immunomodulatory role of Vitamin D in both innate and adaptive immunity has recently been appreciated. In allergic asthma, activation of NF-кB induces transcription of various cytokines and chemokines involved in allergic airway inflammation. The nuclear import of activated NF-кB p50/RelA subunit is dependent on importin α3 (KPNA4) and importin α4 (KPNA3). In this study, we examined the role of importin α3 in immunomodulatory effect of calcitriol in human bronchial smooth muscle cells (HBSMCs).

METHODS

Cultured HBSMCs were stimulated with calcitriol in the presence and absence of cytokines, TNF-α, IL-1β, and IL-10. The mRNA transcripts of importin α3 and α4 were analyzed using qPCR while protein expression of importin α3, α4 and nuclear RelA was analyzed by immunoblotting.

RESULTS

Calcitriol significantly decreased mRNA and protein expression of importin α3 as well as nuclear protein expression of NF-кB p65 (RelA). The decreased activation of RelA by calcitriol was confirmed by decreased release of RelA-inducible molecules, including IL-5, IL-6 and IL-8, by HBSMCs upon calcitriol treatment. Calcitriol attenuated the effect of TNF-α and IL-1β to upregulate mRNA and protein expression of importin α3. IL-10 significantly decreased the TNF-α induced expression of importin α3 and this effect was further potentiated by calcitriol.

CONCLUSIONS

These data suggest that under inflammatory conditions, calcitriol decreases the expression of importin α3 resulting in decreased nuclear import of activated RelA. This could be a novel mechanism by which calcitriol could exert its immunomodulatory effects to reduce allergic airway inflammation and thus may alleviate the symptoms in allergic asthma.

Vitamin D deficiency decreases the expression of VDR and prohibitin in the lungs of mice with allergic airway inflammation

AIMS

Asthma is one of the most common chronic inflammatory diseases of the airways. Calcitriol exerts its action through Vitamin D receptor (VDR), which is a high affinity nuclear receptor. VDR is a transcription factor that alters the transcription of target genes which are involved in a wide spectrum of biological responses. Lower serum vitamin D levels are associated with airway hyperresponsiveness and increased asthma severity. Prohibitin is a ubiquitously expressed protein localized to the cell and mitochondrial membranes and the nucleus.

METHODS AND RESULTS

HBSMCs were cultured and treated with calcitriol and/or TNF-α. The mRNA and protein expression of prohibitin and VDR were analyzed using qPCR and immunoblotting, respectively. In the in vivo studies, female BALB/c mice were fed with special vitamin D-deficient or 2000IU/kg of vitamin D-supplemented diet for 13weeks. Mouse model of allergic airway inflammation was developed by OVA-sensitization and challenge. The expression pattern of TNF-α, prohibitin and VDR in the lung of OVA-sensitized mice was analyzed using immunofluorescence. Calcitriol significantly increased and TNF-α decreased the protein and mRNA expression of prohibitin and VDR in HBSMCs. There was significantly increased expression of TNF-α and decreased expression of VDR and prohibitin in the lung of vitamin D-deficient mouse model of allergic airway inflammation.

CONCLUSION

These results suggest that under inflammatory conditions there is decreased expression of VDR resulting in decreased expression of prohibitin, which is a vitamin D target gene. Vitamin D deficiency causes increase in the expression of TNF-α, thereby increasing inflammation and decreases the expression of VDR and prohibitin. Supplementation with vitamin D might reduce the levels of TNF-α, thereby increasing the expression of VDR and prohibitin that could be responsible for reducing allergic airway inflammation.

Early origins of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide and a significant challenge for adult physicians. However, there is a misconception that COPD is a disease of only adult smokers. There is a growing body of evidence to support the hypothesis that chronic respiratory diseases such as COPD have their origins in early life. In particular, adverse maternal factors will interact with the environment in a susceptible host promoting altered lung growth and development antenatally and in early childhood. Subsequent lung injury and further gene-environment interactions may result in permanent lung injury manifest by airway obstruction predisposing to COPD. This review will discuss the currently available data regarding risk factors in early life and their role in determining the COPD phenotype.

Vitamin D bioavailability in cystic fibrosis: a cause for concern?

Despite the inclusion of extra vitamin D in their regimen of fat-soluble vitamin supplementation, cystic fibrosis patients remain chronically depleted of vitamin D. The persistence of suboptimal vitamin D status is often blamed on the maldigestion and malabsorption of fat. However, the mitigated success of recent clinical trials with high-dose vitamin D supplementation suggests that vitamin D bioavailability might be impaired in these patients. Given the growing understanding of the importance of this vitamin in the regulation of multiple biological functions beyond skeletal health, the present review analyzes the current literature by addressing each step of vitamin D metabolism and action in the context of this life-limiting pathology. In addition, it highlights the importance of vitamin D in relation to organs and or conditions affected by cystic fibrosis.

Fat-soluble vitamins and atopic disease: what is the evidence?

The prevalence of asthma and other atopic disorders continues to increase worldwide. Examination of the epidemiologic patterns has revealed that this rise has occurred primarily in western, industrialised countries and countries transitioning to this lifestyle. While many changes have occurred in human populations over the years, it has been hypothesised that some of the relevant changes that have led to the rise in asthma and atopic disorders have been the changes from a traditional diet to a more western diet consisting of decreased intake of fruits and vegetables (sources of antioxidant vitamins and carotenoids) leading to decreased intakes of vitamins E and A, and a decrease in sun exposure (e.g. greater time spent indoors and heavy use of sunscreen) leading to decreased circulating levels of vitamin D. This review will examine the evidence for an effect of fat-soluble vitamins (vitamins A, D and K) on the development and severity of asthma and allergies. While observational studies suggest that these vitamins may play a salutary role in asthma and allergies, large, well-designed clinical trials are lacking. Of the fat-soluble vitamins, vitamin D holds great promise as an agent for primary and secondary prevention of disease. Ongoing clinical trials will help determine whether results of observational studies can be applied to the clinical setting.

Asthma, allergy and respiratory infections: the vitamin D hypothesis

The recent discovery that every tissue in the human body has vitamin D receptors and that vitamin D has pleiotropic effects has prompted an increased interest in this hormone. Vitamin D deficiency is widespread and on the increase. There is no consensus on the serum vitamin D levels to consider appropriate for global health, the cutoffs for its deficiency, or the doses to use for its supplementation. Vitamin D seems to correlate closely with host reactions against various respiratory infections. Epidemiological studies have shown that low serum 25-hydroxyvitamin D levels are associated with a higher risk of upper and lower respiratory infections in children and a shortage of vitamin D may contribute to asthmatic patients' symptoms and morbidity rates. There are studies highlighting associations between childhood asthma, fetal lung and/or immune development, and maternal vitamin D intake. An insufficiency of this vitamin also seems to be implicated in the onset of childhood atopy and food allergies. The hypothesis is that vitamin D could have a central role in these pathological situations and that it may represent a novel preventive and/or therapeutic strategy. This article reviews and discusses published data on the relationship between vitamin D and asthma and allergy, emphasizing the need for controlled, prospective studies on vitamin D supplementation to clarify whether it has a role in the prevention of and treatment for asthma and allergic conditions.

Vitamin D and Chronic Obstructive Pulmonary Disease

Vitamin D is an important regulator of calcium and bone homeostasis. It is also involved in the regulation of different genes and cellular functions, particularly in the context of inflammation, regeneration and immune control. Conversely, vitamin D deficiency which is often found in chronic, infectious and inflammatory diseases is thought to drive or enhance uncontrolled inflammation. Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation of the airways most often because of cigarette smoking. It has been recognized that repetitive airway infections and systemic consequences or co-morbidities also contribute to the progressive nature of COPD. Vitamin D deficiency is known to sneak in from the early stages of COPD, to become highly prevalent at the more severe stages, and may thereby catalyse airway infection, inflammation and systemic consequences. Undoubtedly, vitamin D deficiency enhances bone resorption and osteoporosis in COPD for which appropriate vitamin D supplementation is recommended. However, conflicting evidence has emerged on the extra-calcemic effects of vitamin D in COPD. A recent intervention trial with high-dose supplementation in COPD was only able to reduce exacerbation frequency in the subgroup of patients with lowest baseline vitamin D levels. It confirms that severe vitamin D deficiency is a health hazard but that more clinical and experimental studies are needed to explore how vitamin D deficiency may affect airway biology and systemic effects in the context of smoke-induced lung diseases.

Vitamin D and allergic disease: sunlight at the end of the tunnel?

A role for vitamin D in the regulation of immune function was first proposed after the identification of Vitamin D receptors in lymphocytes. It has since been recognized that the active form of vitamin D, 1α,25(OH)₂D₃, has direct affects on naïve and activated helper T cells, regulatory T cells, activated B cells and dendritic cells. There is a growing body of literature linking vitamin D (serum 25(OH)D, oral intake and surrogate indicators such as latitude) to various immune-related conditions, including allergy, although the nature of this relationship is still unclear. This review explores the findings of epidemiological, clinical and laboratory research, and the potential role of vitamin D in promoting the inappropriate immune responses which underpin the rise in a broad range of immune diseases.

Relationship between serum vitamin D, disease severity, and airway remodeling in children with asthma

RATIONALE

Little is known about vitamin D status and its effect on asthma pathophysiology in children with severe, therapy-resistant asthma (STRA).

OBJECTIVES

Relationships between serum vitamin D, lung function, and pathology were investigated in pediatric STRA.

METHODS

Serum 25-hydroxyvitamin D [25(OH)D(3)] was measured in 86 children (mean age, 11.7 yr): 36 with STRA, 26 with moderate asthma (MA), and 24 without asthma (control subjects). Relationships between 25(OH)D(3), the asthma control test (ACT), spirometry, corticosteroid use, and exacerbations were assessed. Twenty-two of 36 children with STRA underwent fiberoptic bronchoscopy, bronchoalveolar lavage, and endobronchial biopsy with assessment of airway inflammation and remodeling.

MEASUREMENTS AND MAIN RESULTS

25(OH)D(3) levels (median [IQR]) were significantly lower in STRA (28 [22-38] nmol/L) than in MA (42.5 [29-63] nmol/L) and control subjects (56.5 [45-67] nmol/L) (P < 0.001). There was a positive relationship between 25(OH)D(3) levels and percent predicted FEV(1) (r = 0.4, P < 0.001) and FVC (r = 0.3, P = 0.002) in all subjects. 25(OH)D(3) levels were positively associated with ACT (r = 0.6, P < 0.001), and inversely associated with exacerbations (r = -0.6, P < 0.001) and inhaled steroid dose (r = -0.39, P = 0.001) in MA and STRA. Airway smooth muscle (ASM) mass, but not epithelial shedding or reticular basement membrane thickness, was inversely related to 25(OH)D(3) levels (r = -0.6, P = 0.008). There was a positive correlation between ASM mass and bronchodilator reversibility (r = 0.6, P = 0.009) and an inverse correlation between ASM mass and ACT (r = -0.7, P < 0.001).

CONCLUSIONS

Lower vitamin D levels in children with STRA were associated with increased ASM mass and worse asthma control and lung function. The link between vitamin D, airway structure, and function suggests vitamin D supplementation may be useful in pediatric STRA.

Vitamin D and asthma

Vitamin D deficiency and asthma are common conditions that share risk factors such as African American ethnicity, inner-city residence, and obesity. This review provides a critical examination of current experimental and epidemiologic evidence of a causal association between vitamin D status and asthma or asthma morbidity, including potential protective mechanisms such as antiviral effects and enhanced steroid responsiveness. Because most published epidemiologic studies of vitamin D and asthma or asthma morbidity are observational, a recommendation for or against vitamin D supplementation as preventive or secondary treatment for asthma is not advisable and must await results of ongoing clinical trials. Should these trials confirm a beneficial effect of vitamin D, others will be needed to assess the role of vitamin D supplementation to prevent or treat asthma in different groups such as infants, children of school age, and ethnic minorities.

Invariant NKT cell defects in vitamin D receptor knockout mice prevents experimental lung inflammation

Vitamin D receptor (VDR) deficiency (knockout [KO]) results in a failure of mice to generate an airway hyperreactivity (AHR) response on both the BALB/c and C57BL/6 background. The cause of the failed AHR response is the defective population of invariant NKT (iNKT) cells in the VDR KO mice because wild-type (WT) iNKT cells rescued the AHR response. VDR KO mice had significantly fewer iNKT cells and normal numbers of T cells in the spleen compared with WT mice. In BALB/c VDR KO mice, the reduced frequencies of iNKT cells were not apparent in the liver or thymus. VDR KO and WT Th2 cells produced similar levels of IFN-γ and IL-5. On the BALB/c background, Th2 cells from VDR KO mice produced less IL-13, whereas on the C57BL/6 background, Th2 cells from VDR KO mice produced less IL-4. Conversely, VDR KO iNKT cells were defective for the production of multiple cytokines (BALB/c: IL-4, IL-5, and IL-13; C57BL/6: IL-4 and IL-17). Despite relatively normal Th2 responses, BALB/c and C57BL/6 VDR KO mice failed to develop AHR responses. The defect in iNKT cells as a result of the VDR KO was more important than the highly susceptible Th2 background of the BALB/c mice. Defective iNKT cell responses in the absence of the VDR result in the failure to generate AHR responses in the lung. The implication of these mechanistic findings for human asthma requires further investigation.

Low concentrations of serum 25-hydroxyvitamin D associated with increased risk for chronic bronchitis among US adults

Increasing evidence suggests that vitamin D benefits both innate and adaptive immunity, thereby eliciting an anti-inflammatory effect and reducing the risk of infectious disease. The present study examined the association between serum 25-hydroxyvitamin D (25(OH)D) levels and the risk of chronic bronchitis among US adults. We analysed data from 6872 US adults aged ≥ 20 years who participated in the 2003-6 National Health and Nutrition Examination Survey. Prevalence and OR with 95 % CI of having self-reported chronic bronchitis were estimated by quintiles of 25(OH)D or vitamin D-deficiency status after adjustment for potential confounders. The results showed that the adjusted prevalence of chronic bronchitis ranged from 2.4 (95 % CI 1.4, 3.3) % among adults in the highest quintile of 25(OH)D ( ≥ 30 ng/ml) to 4.1 (95 % CI 2.5, 5.6) % among adults in the lowest quintile ( < 15 ng/ml; P for trend < 0.01). The adjusted OR for chronic bronchitis was 1.85 (95 % CI 1.06, 3.24) in adults with < 15 ng/ml 25(OH)D and 1.77 (95 % CI 1.19, 2.65) in those with 15 to < 20 ng/ml 25(OH)D compared with adults with ≥ 30 ng/ml 25(OH)D. Additionally, the adjusted OR for chronic bronchitis was 1.52 (95 % CI 1.03, 2.26) among adults with vitamin D deficiency ( < 20 ng/ml 25(OH)D) compared with those with ≥ 20 ng/ml 25(OH)D. For every 1 ng/ml increase in 25(OH)D, the likelihood of having chronic bronchitis fell by 2.6 % (P = 0.016). In conclusion, low serum 25(OH)D levels are associated with the increased risk of chronic bronchitis among US adults. The present results provide support for continuing research on the role of vitamin D in lung diseases.

Vitamin d and susceptibility of chronic lung diseases: role of epigenetics

Vitamin D deficiency is linked to accelerated decline in lung function, increased inflammation, and reduced immunity in chronic lung diseases. Epidemiological studies have suggested that vitamin D insufficiency is associated with low lung function in susceptible subjects who are exposed to higher levels of environmental agents (airborne particulates). Recent studies have highlighted the role of vitamin D and vitamin D receptor (VDR) in regulation of several genes that are involved in inflammation, immunity, cellular proliferation, differentiation, and apoptosis. Vitamin D has also been implicated in reversal of steroid resistance and airway remodeling, which are the hallmarks of chronic obstructive pulmonary disease (COPD) and severe asthma. VDR protein level is decreased in lungs of patients with COPD. VDR deficient mice develop an abnormal lung phenotype with characteristics of COPD, such as airspace enlargement and decline in lung function associated with increased lung inflammatory cellular influx, and immune-lymphoid aggregates formation. Dietary vitamin D may regulate epigenetic events, in particular on genes which are responsible for COPD susceptibility. Active metabolite of vitamin D, 1,25-dihydroxyvitamin D₃ plays an essential role in cellular metabolism and differentiation via its nuclear receptor (VDR) that cooperates with several other chromatin modification enzymes (histone acetyltransferases and histone deacetylases), thereby mediating complex epigenetic events in vitamin D signaling and metabolism. This review provides an update on the current knowledge and understanding on vitamin D, and susceptibility of chronic lung diseases in relation to the possible role of epigenetics in its molecular action. Understanding the molecular epigenetic mechanism of vitamin D/VDR would provide rationale for dietary vitamin D-mediated intervention in prevention and management of chronic lung diseases linked with vitamin D deficiency.

Genetic analysis of lung function in inbred mice suggests vitamin D receptor as a candidate gene

Vitamin D receptor (VDR) polymorphisms are associated with an increased asthma incidence in human populations; however, observations in Vdr knockout mice are unclear. The aim of our study was to determine the influence of the genetic variation in Vdr among inbred strains on lung resistance (i.e., dynamic and airway resistance). In an intercross between the strains C57BL/6J (B6) and KK/HlJ (KK), we identified that a significant QTL for dynamic resistance on Chr X was interacting with a QTL on Chr 15. The Chr 15 QTL peak was located in close proximity to the Vdr locus. We further examined if phenotypes of several inbred strains with varying Vdr genotypes differed. Strains with a B6-like genotype on the Vdr locus had significantly lower airway resistance than strains with a KK-like genotype. Vdr knockout mice were examined for dynamic resistance and showed significantly higher resistance than mice with one (i.e., heterozygous) or both copies (i.e., wild-type) of the Vdr. In comparison to B6, the strain A/J is more resistant but carries the same genotype at the Vdr locus. Dietary vitamin D manipulation in the strain A/J did not rescue the high airway resistance phenotype. Finally, we observed that serum vitamin D does not correlate significantly with lung resistance parameters in a survey of 18 strains. Conclusively, Vdr contributes to the phenotypic variation of lung resistance in inbred mice but other molecules in the Vdr pathway and extended network [i.e., Chr X gene(s)] may contribute as well.

Modulation of the immune system by UV radiation: more than just the effects of vitamin D?

Humans obtain most of their vitamin D through the exposure of skin to sunlight. The immunoregulatory properties of vitamin D have been demonstrated in studies showing that vitamin D deficiency is associated with poor immune function and increased disease susceptibility. The benefits of moderate ultraviolet (UV) radiation exposure and the positive latitude gradients observed for some immune-mediated diseases may therefore reflect the activities of UV-induced vitamin D. Alternatively, other mediators that are induced by UV radiation may be more important for UV-mediated immunomodulation. Here, we compare and contrast the effects of UV radiation and vitamin D on immune function in immunopathological diseases, such as psoriasis, multiple sclerosis and asthma, and during infection.