Vitamin D plasma concentration and vitamin D receptor genetic variants confer risk of asthma: A comparison study of Taiwanese and Mongolian populations

The Association of Vitamin D Receptor Gene Polymorphisms with Vitamin D, Total IgE, and Blood Eosinophils in Patients with Atopy

BACKGROUND

In order to improve the control of atopic diseases, it is important to clarify the pathogenesis of atopy and identify its various triggers. Single nucleotide polymorphisms (SNPs) of the vitamin D receptor gene (VDR) may impact atopy. The aim of this study was to investigate the possible associations between VDR SNPs and vitamin D, total IgE, and eosinophils in atopy.

METHODS

In total, 203 adults, including 122 patients with atopic diseases (45 with atopic dermatitis, 77 with allergic asthma) and 81 healthy controls, were involved in the study. The blood eosinophil count was determined with an automated hematology analyzer. Vitamin D and total immunoglobulin E (IgE) levels were evaluated using the ELISA method. Polymorphisms in the VDR gene were analyzed with real-time PCR using TaqMan probes.

RESULTS

We analyzed six VDR single nucleotide polymorphisms and found a significant association between VDR rs731236 GG genotype and normal vitamin D levels in atopic patients and healthy subjects (OR 11.33; 95% CI: 1.049-122.388 and OR 4.04; 95% CI: 1.117-14.588, respectively, p < 0.05). Additionally, the study results revealed a significant relationship between the VDR rs2228570 GG genotype and normal vitamin D levels in patients with atopy and healthy subjects (OR 3.80; 95% CI: 1.190-12.134 and OR 2.09; 95% CI: 1.044-4.194, respectively, p < 0.05). The rs2228570 allele A was associated with decreased vitamin D levels in patients with atopy and healthy subjects (OR 0.28; 95% CI: 0.098-0.804 and OR 0.229; 95% CI: 0.069-0.761, respectively, p < 0.05). The VDR rs3847987 genotypes AA and AC were significantly associated with normal vitamin D levels in healthy subjects (OR 35.99; 95% CI: 6.401-202.446 and OR 4.72; 95% CI: 1.489-15.007, respectively, p < 0.05). In addition, a decreased amount of vitamin D was associated with atopic diseases such as atopic dermatitis and allergic asthma (OR 0.49; 95% CI: 0.439-1.308 and OR 0.58; 95% CI: 0.372-0.908, respectively, p < 0.05). The rs11168293 allele T was associated with the normal range of total IgE in atopy (OR 2.366; 95% CI: 1.133-5.027; p < 0.05). Significant associations were found between VDR rs731263 allele G, rs11168293 allele G, and increased blood eosinophil levels in patients with atopy (OR 0.319; 95% CI: 0.163-0.934 and OR 0.323; 95% CI: 0.112-0.935, respectively, p < 0.05).

CONCLUSIONS

A decreased vitamin D level showed a significant relationship with atopic diseases (atopic dermatitis and allergic asthma). The association between the VDR gene polymorphisms rs2228570, rs731236, and rs11168293 and vitamin D, total IgE, and blood eosinophils in patients with atopy suggested that VDR polymorphisms and the vitamin D level should be considered when examining the factors associated with atopy.

Genetic Diversity in Bronchial Asthma Susceptibility: Exploring the Role of Vitamin D Receptor Gene Polymorphisms in Varied Geographic Contexts

Bronchial asthma (BA) exhibits varying prevalence across global populations, prompting a comprehensive investigation into genetic and environmental determinants. Vitamin D is a potent immunomodulator capable of suppressing inflammatory signals in several cell types involved in the asthmatic response; it exerts effects on the immune system by binding to the nuclear vitamin D receptor (VDR). VDR gene genetic variations are affecting serum vitamin D levels with a possible role in the BA risk. The current study aimed to examine the complex interaction of various factors (genetic background, serum vitamin D levels, and geographic location) to identify differences in the influence of these factors on the susceptibility to asthma between populations at different latitudes. Focusing on Eastern European cohorts from Latvia and Lithuania and comparing them with published data on East Asian populations, we explore the impact of VDR gene polymorphisms on BA susceptibility. Genotyping four key VDR SNPs and assessing their association with 25-hydroxyvitamin D levels, our study unveils significant associations of the studied loci with the risk of asthma-both risk-reducing and increasing effects, differently distributed between Baltic and East Asian populations. The functional effects of in silico VDR gene genetic variations are also identified and discussed.

Association of polymorphisms of vitamin D gene in children with asthma and allergic rhinitis - Hospital based study

Vitamin D gene polymorphisms are known to be associated with asthma and allergic rhinitis in children. However, the genetic association of the same in South Indian children with above condition is still unknown. The present study was designed with the objective to analyze the association of polymorphisms of vitamin D receptor gene (VDR) (rs797532, rs154410, rs2258470, rs731236) and transport gene of vitamin D (rs7041) in children with asthma and allergic rhinitis in South India. Children (1-18years) presenting with symptoms suggestive of asthma and allergic rhinitis to hospital based outpatient department, in Vellore, South India were recruited as cases and children presenting with minor illness without respiratory complaints were enrolled as controls during January 2018 to September 2021. Polymorphisms were genotyped using tetra-arms PCR. Significant increase in levels of absolute eosinophil counts and serum IgE levels with decrease in vitamin D levels was seen among the cases. Significant association between levels of vitamin D and serum IgE was also observed. Analysis of polymorphisms showed that, in comparison to homozygous major allele the odds of having heterozygous (OR0.55 (0.3, 0.99) and homozygous minor form (OR0.52 (0.28, 0.97) of rs7975232, homozygous minor (OR 0.51 (0.34, 0.76)) and alternate allele (OR 0.7 (0.53, 0.93)) of rs154410 and homozygous minor form (OR 0.57 (0.37, 0.88) of rs731236 was significantly lesser among the cases. Genotypic model of rs154410 (p0.023) and allele form of rs7041 (p 0.041) were significantly associated with vitamin D levels however no association of gene blocks with cases was seen in haplotype analysis. There was an apparent gene pool difference noted in comparative analysis between Indian studies. The study is the first in south India to analyze levels of serum IgE, Vitamin D levels, association of VDR polymorphisms, and rs7041 in children with asthma.

Vitamin D receptor and vitamin D binding protein gene polymorphisms in patients with asthma: a pilot study

BACKGROUND

The effects of vitamin D are exerted by interaction with the vitamin D receptor (VDR) and vitamin D binding protein (VDBP). Polymorphisms in VDR or VDBP genes may affect vitamin D levels, influencing the pathogenesis of asthma and atopy. The aim of this study was to investigate the possible association of VDR and VDBP gene single-nucleotide polymorphisms (SNP), 25-hydroxyvitamin D (25(OH)D), blood eosinophils and total IgE level in subjects with asthma in comparison with healthy individuals.

METHODS

This case-control study enrolled 63 subjects with asthma (45 allergic and 18 non-allergic) and 32 healthy subjects were involved in the study. Sensitization of subjects to inhaled allergens was determined by a skin prick test, lung function was evaluated by spirometry. Blood eosinophil count was determined by standard methods. Serum 25(OH)D and total IgE levels were evaluated by ELISA. Polymorphisms in the VDR and VDBP genes on the 12q13.11 and 4q13.3 chromosomal region were analyzed using TaqMan SNP Genotyping Assay probes.

RESULTS

In asthma patients with vitamin D deficiency (< 20 ng/ml) the allele G of rs11168293 of VDR was more common than in those having insufficiency (20-30 ng/ml) of vitamin D (63% and 31%, p < 0.05). Moreover, asthmatic subject with rs11168293 G allele has significant higher blood eosinophil count compared to asthmatic without the rs11168293 G allele (8.5 ± 12.3% vs. 5.1 ± 1.5%, p < 0.05). Significantly higher IgE level was found in subjects with allergic asthma with the allele A of rs7041 on VDBP gene than in those without this allele (540 ± 110 and 240 ± 80 IU/ml, p < 0.05).

CONCLUSIONS

The association of polymorphisms in VDBP and VDR gene, the rs11168293 G allele and the rs7041 A allele, with 25(OH)D, blood eosinophil and total IgE level in asthma, let us suggest that vitamin D, VDR and VDBP gene polymorphisms are important in pathogenesis of asthma despite its form in relation to atopy.

Association between Single Nucleotide Polymorphisms Related to Vitamin D Metabolism and the Risk of Developing Asthma

Asthma is a chronic non-communicable disease that affects all age groups. The main challenge this condition poses is its heterogeneity. The role of vitamin D in asthma has aroused great interest, correlating low vitamin D levels and polymorphisms in the genes involved in its metabolic pathway with the risk of asthma. The aim of this study was to evaluate the influence of 13 single nucleotide polymorphisms (SNPs) related to the vitamin D metabolism on the susceptibility to asthma. An observational case-control study was performed, including 221 patients with asthma and 442 controls of Caucasian origin from southern Spain. The SNPs CYP24A1 (rs6068816, rs4809957), CYP27B1 (rs10877012, rs4646536, rs703842, rs3782130), GC (rs7041), CYP2R1 (rs10741657) and VDR (ApaI, BsmI, FokI, Cdx2, TaqI) were analyzed by real-time PCR, using TaqMan probes. The logistic regression model adjusted for body mass index revealed that in the genotype model, carriers of the Cdx2 rs11568820-AA genotype were associated with a higher risk of developing asthma (p = 0.005; OR = 2.73; 95% CI = 1.36-5.67; AA vs. GG). This association was maintained in the recessive model (p = 0.004). The haplotype analysis revealed an association between the ACTATGG haplotype and higher risk of asthma for the rs1544410, rs7975232, rs731236, rs4646536, rs703842, rs3782130 and rs10877012 genetic polymorphisms (p = 0.039). The other SNPs showed no effect on risk of developing asthma. The Cdx2 polymorphism was significantly associated with the susceptibility of asthma and could substantially act as a predictive biomarker of the disease.

Vitamin D and asthma occurrence in children: A systematic review and meta-analysis

PROBLEM

The association between serum 25-Hydroxyvitamin D (25-OHD) level and asthma occurrence in children was controversial.

ELIGIBILITY CRITERIA

The Pubmed, Ovid Medline, Embase, Cochrane Library were systematically searched up to April 13th 2020. All the study measured the serum 25-OHD level in children, or classified the children based on the 25-OHD level into severe vitamin D deficiency, insufficient deficiency and comparing the prevalence of asthma in childhood were included in our study.

SAMPLE

A total of 35 studies were included in our meta-analysis. Among them, 24 studies were included for analyzing the association between 25-OHD level and asthma, and 12 studies evaluated the treatment effect of vitamin D.

RESULTS

The children with asthma (5711 participants) had significant lower 25-OHD level than children without asthma (21,561 participants) (21.7 ng/ml versus 26.5 ng/ml, SMD = -1.36, 95% = -2.40--0.32, P = 0.010). Besides, the children with asthma treated with vitamin D supplement had a significantly lower recurrence rate than the placebo group (18.4% versus 35.9%, RR = 0.35, 95%CI = 0.35-0.79, P = 0.002).

CONCLUSIONS

Children with asthma had a lower 25-OHD level than healthy children. Vitamin D supplement could decrease the asthma recurrence rate in the follow-up years.

IMPLICATIONS

This study implies that lower 25-OHD may cause asthma in childhood.

Vitamin D receptor gene polymorphisms in atopy

Background

The occurrence of allergic conditions, for example allergic asthma, rhinitis, and atopic dermatitis, is rising worldwide. These allergic conditions are associated with poor life quality. Vitamin D is proposed to be linked with increased risk and severe forms of allergic diseases.

Aims

This review article aimed to evaluate the vitamin D level role and polymorphisms of vitamin D receptor gene (VDR) in atopy.

Methods & Materials

We analyzed publications that were focusing on levels of vitamin D and/or polymorphism analysis of vitamin D receptor gene in allergic asthma, rhinitis, and atopic dermatitis patients.

Results

We noticed that levels of vitamin D are extensively studied in atopy by many research groups, however, polymorphisms of vitamin D receptor gene and their link with levels of vitamin D lack comprehensive data. There is evidence that vitamin D may be associated with anti‐inflammatory effects in allergic diseases. Some of VDR polymorphisms also may play a role in pathogenesis of these diseases. However, the data from different studies are controversial.

Discussion

The results of different studies are usually inconsistent, most probably due to populational bias or differences in methodology. Even though, more evidence shows a positive impact of vitamin D on the risk and outcomes of allergic diseases, especially atopic dermatitis, and asthma.

Conclusions

There is controversial data about the level of vitamin D and its role in atopy; however, more evidence shows a positive impact on the risk and outcomes of allergic diseases.

Association of vitamin D gene polymorphisms in children with asthma - A systematic review

INTRODUCTION

The association of Vitamin D and children with asthma is known and there are several individual studies on Vitamin D polymorphisms. However, systematic reviews on all vitamin D associated gene polymorphisms have not been done in children with asthma.

OBJECTIVE

To investigate the association of Vitamin D associated gene polymorphisms and asthma in children (0-18 years) by systematic review and meta-analytic approach.

METHODS

Our search included 20 full text articles of which 15 were case control studies and 5 used family based linkage disequilibrium method. Total of 2491cases and 3682 controls were included in case control studies, with mean age of 9.58 years and 10.16 years respectively. Quantitative and qualitative analysis were done.

RESULTS

Quantitative analysis revealed significant association with protective effect of Apa1 polymorphism in allele (OR 0.81 (0.71,0.91) and homozygous major form (OR 0.83 (0.70,0.98) and Taq 1 minor allele in homozygous form (OR 0.73 (0.58,0.92) in children with asthma. However, the minor allele of Apa1(OR 1.21 (1.07,1.37), Bsm 1 in heterozygous (OR 1.35 (1.07,1.71) and homozygous minor form (OR 1.95 (1.59,2.39), major allele of Fok1(OR1.34 (1.17,1.52) and Taq1 (OR 1.22 (1.08,1.38) were found to be increasing the odds of asthma. Ethnic variations were noted in subgroup analysis. Qualitative analysis of the polymorphisms of the Vitamin D associated metabolic genes also showed significant associations.

CONCLUSION

Our review shows significant associations with VDR polymorphisms - Apa1, Bsm1, Fok 1, Taq 1, polymorphisms of Vitamin D metabolic genes - CYP27A1, CYP 2R1, CYP 24A1, GC and genes related to Vitamin D response element (VDRE) in children with asthma. Conducting large studies involving various ethnic regions will strengthen our knowledge on the association and aid in targeted interventions for control of asthma in children.