VITAMIN D RECEPTOR GENE MUTATIONS AND VITAMIN D SERUM LEVELS IN ASTHMATIC CHILDREN

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 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.

The role of vitamin D in the severity and control of asthma in children and adolescents: A protocol for systematic review and meta-analysis

BACKGROUND

Vitamin D plays an important role in the immune system and consequently in the inflammatory process of asthma. It acts directly on the regulation of helper T lymphocytes 1 (Th1) and helper T lymphocytes 2 (Th2) cells, and regulatory T lymphocytes. Evidence shows that vitamin D acts on dendritic cells, raising inflammatory mediators and increasing the imbalance between Th1, Th2, and helper T lymphocytes 17 (Th17). Evidence shows a strong association between vitamin D levels and asthma incidence, especially in patients with severe and uncontrolled asthma.

METHODS

A systematic and comprehensive search will be performed using four main databases, PubMed, EMBASE, Cochrane Library, and Web of Science. Articles will be searched from the earliest available time to august 2022. The studied population will be composed of children and or adolescents with asthma. From the data obtained, all articles found will be transferred to the Rayyan platform. Study selection will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Checklist (PRISMA P-2020). In addition, if sufficient data are available, a meta-analysis will be conducted. Two independent reviewers will conduct the studies selection, data extraction, and risk of bias assessment. The outcome measures will be to analyze the serum levels of vitamin D in patients with asthma and to relate this hormone to the control and severity of the disease and its anti- inflammatory effect.

RESULTS

A systematic review will provide better knowledge regarding vitamin D and its role in the severity and control of asthma.

CONCLUSIONS

The findings of this study will be published in a peer-reviewed journal.

Association of vitamin D receptor gene polymorphisms in North Indian children with asthma: a case-control study

Asthma is a complex genetic disease. Vitamin D and vitamin D receptor (VDR) gene polymorphisms are involved in asthma pathogenesis. However, accurate inflammatory mechanisms and their role in VDR gene polymorphisms are unclear. The objective of this study was to investigate the association of VDR gene polymorphisms, ApaI, FokI, TaqI, and BsmI with asthma as compared to controls. Children (age 5-15 years) with a history of respiratory symptoms (wheeze, shortness of breath and chest tightness) were recruited as cases. Age matched children admitted with central nervous system disorders (encephalitis/seizures) without any respiratory complaints were recruited as controls after parental consent. Children with a clinical diagnosis of cystic fibrosis, congenital heart disease and whose parents did not consent for participation in the study were excluded. VDR gene polymorphisms were genotyped using PCR-RFLP method. One hundred and sixty asthmatics and one hundred controls were enrolled in this study. Mean age of the cases was 103.29±32.7 months and controls 94.24±30.52 months. Children with heterozygous (AC) genotype [OR=1.83, 95% CI=1.01-3.32, p=0.046] of ApaI polymorphism were found to be associated with the risk of asthma. Our findings suggest that ApaI polymorphism of VDR gene may contribute to asthma susceptibility among children.

The Effect of Vitamin D Supplementation on Clinical Outcomes of Asthmatic Children with Vitamin D Insufficiency

BACKGROUND

The extensive impacts of vitamin D on the immune system has gathered the attention of scholars in last years. In this regard, studies about vitamin D and incidence of asthma have showed various results. The aim of this study was to evaluate the effect of vitamin D supplements on clinical outcomes in asthmatic children with vitamin D insufficiency.

MATERIALS & METHODS

This before-after interventional study was conducted on all asthmatic children who attended the Be'sat Hospital, Iran. Serum levels of 25(OH)D, asthma severity and pulmonary function tests before and after therapeutic prescription of vitamin D were evaluated. Serum levels of 25(OH)D were measured by enzyme-linked immunosorbent assay.

RESULTS

The mean age of the samples was 10.69±9.78 years and 39 subjects (57.4%) were male. The primary mean level of serum 25(OH)D (18.21±8.22, ng/mL) has significantly (p<0.05) increased after treatment (35.45±9.35, ng/mL). Also, asthma severity, forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and FEV1/FVC indicators were significantly (p<0.05) increased after treatment.

CONCLUSION

We can conclude that therapeutic prescription of vitamin D is very effective in improving the clinical status of asthmatic children.

Vitamin D: association with eosinophil counts and IgE levels in children with asthma

In this cross-sectional study, we investigated the relationship that levels of vitamin D had with eosinophil counts and IgE levels in 26 children with asthma (6-12 years of age) in the city of Londrina, Brazil. Vitamin D levels were found to correlate significantly, albeit moderately, with age (r = −0.51) and eosinophilia (r = −0.49), although not with IgE levels (r = −0.12). When we stratified the sample into two groups by the median vitamin D level (< or ≥ 24 ng/mL), we found that those in the < 24 ng/mL group were older, had higher eosinophil counts, and had higher IgE levels. To our knowledge, this is the first study to show an association between low levels of vitamin D and more pronounced eosinophilia in children with asthma in Brazil.

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.

The Immunomodulatory Role of Vitamin D in Respiratory Diseases

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The growing interest in the new role of vitamin D, particularly as an immunomodulatory factor, has spurred basic research and the development of clinical trials to better understand the influence of supplementation on various diseases. Vitamin D is an important nutrient factor in human health due to its role in calcium metabolism regulation, cellular growth, differentiation and its fundamental discovered activity in immune functions. It has influenced different diseases, particularly inflammatory and autoimmune diseases, through immune response regulation, modulating innate and adaptive immunity.

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The aim of this review was to explore the role of vitamin D in the main respiratory diseases in children such as asthma, chronic rhinosinusitis, cystic fibrosis and recurrent respiratory infections.

Influence of vitamin D receptor gene FokI and ApaI polymorphisms on glucocorticoid response in patients with asthma

BACKGROUND

Glucocorticoid (GC)-resistant asthma, a complex disease phenotype, has a high morbidity and mortality and takes up a disproportionate share of healthcare costs. The aim of this work was to assess serum 25-hydroxyvitamin D (25(OH)VD) levels in steroid-resistant, steroid-sensitive patients with asthma and in healthy controls, and to investigate the association between the vitamin D receptor gene (VDR) FokI and ApaI polymorphisms and GC resistance in patients with asthma.

METHODS

This case-control study included 70 patients with severe bronchial asthma and 30 apparently healthy controls. Atopic status was determined by skin-prick test reaction to the most common locally-encountered allergens. A GC reversibility test was performed to differentiate between GC-sensitive and GC-resistant asthma. For all subjects, analysis of the VDR FokI and ApaI polymorphisms by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and measurement of serum 25(OH)VD levels by enzyme-linked immunosorbent assay (ELISA) were performed.

RESULTS

The frequencies of FokI polymorphism genotypes and alleles differed significantly between patients with asthma and controls. The frequencies of the TT genotype and T allele carriers were significantly higher among patients with asthma than among controls, and also among GC-resistant patients with asthma than among GC-sensitive patients with asthma. Additionally, serum 25(OH)VD levels differed significantly among the 3 VDR FokI polymorphic genotypes in GC-resistant patients with asthma; the highest level was detected in the TT genotype. No significant differences in ApaI were found.

CONCLUSION

We found a possible association between the FokI T allele and GC resistance in patients with asthma. Variations in VDR FokI might also play a role in 25(OH)VD levels.