Should vitamin D supplementation be a regular part of asthma care?

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 deficiency and level of asthma control in women from North of Jordan: a case-control study

INTRODUCTION

Reduced vitamin-D levels in patients with asthma have been associated with impaired lung function, increased airway hyper-responsiveness, and reduced glucocorticoid responsiveness. Nationwide studies revealed a considerable prevalence of vitamin-D deficiency (VDD) in Jordanian women.

OBJECTIVE

A case-control study was conducted to determine the relationship between serum vitamin A and D levels and asthma among women in North of Jordan.

METHODS

Sixty-eight asthmatics, age range between 14 and 65 years and 77 healthy women, age range between 19 and 51 years, were enrolled. Asthma severity was classified using Global Initiative for Asthma (GINA) guidelines and Asthma Control Test (ACT) questionnaire. Serum vitamin-A and 25-hydroxyvitamin-D (25(OH)D3) levels were measured using high-performance liquid chromatography (HPLC) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods, respectively.

RESULTS

The prevalence of VDD (<15 ng/ml) was higher but not statistically significant for women with asthma compared with controls (95.6% vs. 87.0%; p = 0.070). The severity of VDD correlated with the number of asthma medications (p = 0.020). 25(OH)-D3 serum levels directly correlated with asthma control level using ACT score (p = 0.012) and GINA classification (p = 0.046). After adjusting for age, the odds of having VDD for asthmatic women were 35.9 times higher than that for women with no asthma. There was no difference in serum vitamin-A level between healthy and asthmatic women (p = 0.214) and none had vitamin-A deficiency (<200 µg/dl).

CONCLUSIONS

VDD is prevalent in women with asthma in northern Jordan. The severity of VDD correlated with poor asthma control and a need for more medications to control asthma. There was no association between vitamin-A and asthma.

Identification of proteasome subunit beta type 3 involved in the potential mechanism of corticosteroid protective effectiveness on beta-2 adrenoceptor desensitization by a proteomics approach

BACKGROUND

Asthma is a chronic inflammatory disease characterized by airway inflammation with mucus hypersecretion and hyperresponsiveness to various nonspecific stimuli. Corticosteroids are usually used to prevent β2 adrenoceptor (β2AR) desensitization in clinical and experimental practice. But the exact mechanism of corticosteroid effectiveness on β2AR desensitization is unclear.

OBJECTIVES

To find the potential mechanisms related to the protective effects of corticosteroid on salbutamol induced β2AR desensitization by a proteomics approach.

METHODS

Thirty-two BALB/c (6-8 weeks old) mice were divided into four groups: group A, control group, phosphate buffered saline (PBS)-treated group; group B, asthmatic group, treated by ovalbumin (OVA); group C, β2AR desensitized asthmatic group, treated by OVA and salbutamol (SBT) and group D, corticosteroid-treated β2AR desensitized asthmatic group, treated with OVA, SBT and Dexamethasone (DEX). After administrated with those drugs, their serum total IgE, bronchoalveolar lavage fluid (BALF) cytokine concentration, airway resistance and membrane receptor number of β2AR were evaluated. After then, the mice of group C and D were sacrificed, their protein from lung tissue were extracted and then seperated by two-dimensional gel electrophoresis (2DE). Then, the isolated protein spots were analyzed by ImageMaster software and mass spectrometry. Bioinformatic tools were used to search these protein spots and find interesting protein spots associated with corticosteroid protective effect on β2AR desensitization. Finally, these protein spots were confirmed by Western blotting.

RESULTS

With inflammatory cell count, cytokine concentration of BALF, pathological sections, total serum IgE, airway resistance, membrane receptor number and β2AR total amount changes, asthmatic mouse model and β2AR desensitization asthmatic mouse model were successfully established. Seventeen protein spots were found different expression between group C and group D, 4 protein spots were down-regulated and 13 protein spots were up-regulated compared to group C. Proteasome subunit beta type 3 was down-regulated.

CONCLUSIONS

Increased proteasome subunit beta type 3 expression may be responsible for salbutamol-induced β2AR desensitization in asthmatic disease, and DEX possibly render the β2AR resensitization partially by decreasing the content of proteasome.