Correlation between Serum Vitamin D Binding Protein and Serum Calcium in Bronchial Asthma and the Effects of Single Nucleotide Polymorphisms

Abstract

Bronchial asthma (BA) is characterized by airway stenosis due to chronic airway inflammation. CYP2R1 is an enzyme primarily responsible for vitamin D metabolism, and some of its single nucleotide polymorphisms (SNPs) have been implicated in BA. Vitamin D binding protein (VDBP) is primarily responsible for vitamin D transport, and some of its SNPs have also been implicated in asthma. Here, we investigated the relationship between serum VDBP, serum 25 (OH) D, and serum calcium, as well as correlations between serum VDBP and laboratory data, in Japanese patients with BA and healthy donors (HDs). We also compared results between genotypes at SNPs of CYP2R1 (rs12794714 and rs10741657) and an SNP of VDBP (rs7041). Serum VDBP levels were significantly higher in the BA group compared with the HD group. Laboratory data did not differ between SNP genotypes in either group. The only parameter significantly correlated with VDBP was serum calcium in both groups. In addition, serum VDBP was correlated with serum calcium in all genotypes in the HD group, but was correlated with only the AA/AG genotype at rs12794714 and rs10741657 and TT/TG genotype at rs7041 in the BA group. Thus, SNP genotypes with an A allele (AA and AG) at rs12794714 and rs10741657 and a T allele (TT and TG) at rs7041, but not the GG genotype, may be involved in the serum VDBP-mediated regulation of serum calcium in BA.