CD14 promoter polymorphisms have no functional significance and are not associated with atopic phenotypes
A polymorphism at CD14/–159 has been reported to be associated with atopic phenotypes in several studies. However, conflicting results from association studies in different populations have been reported. This study aimed to investigate the relationship between CD14 promoter polymorphisms and atopic phenotypes in Singaporean Chinese and the biological characterization of these polymorphisms.Methods
A total of 171 atopic and 160 non-atopic adult subjects were included and their serum soluble CD14 (sCD14) and total immunoglobulin E (tIgE) levels were measured. Screening of single nucleotide polymorphisms (SNPs) in the CD14 promoter was performed using direct PCR-sequencing and restriction fragment length polymorphism methods. The functional significance of SNPs was investigated using reporter assay system.Results
Three previous reported SNPs (CD14/–159, –1145 and –1359) and a novel SNP (CD14/–550) were detected. Significant linkage disequilibrium was found among these four loci of CD14 gene. However, no significant difference was found in the genotype frequencies of these SNPs between non-atopy and atopy groups. Furthermore, no transcriptional activities of these SNPs were detected using reporter gene assay in three cell-lines (HepG-2, THP-1 and U937).Conclusions
This study confirms three reported SNPs and one novel SNP in the CD14 promoter in our local population. However, these SNPs do not play a decisive role in the development of atopic phenotypes.