Impact of DEFB1 gene regulatory polymorphisms on hBD-1 salivary concentration

• DEFB1 5′ untranslated region (UTR) polymorphisms were genotyped in Italian healthy subjects.
• The salivary concentration of human β-defensin 1 (hDB-1) was measured in Italian healthy subjects.
• DEFB1 genotypes were correlated with the hDB-1 salivary concentration.
• The −52 G/G and −44C/G genotype were associated with high protein levels.
• DEFB1 5′UTR genetic variants may influence the hDB-1 expression.

ObjectivesHuman β-defensin 1 (hBD-1) is an antimicrobial peptide involved in epithelial defence of various tissues, also present in the saliva. Individual genetic variations within the DEFB1 gene, encoding for hBD-1, could influence gene expression and protein production.DesignThree DEFB1 polymorphisms at 5′ untranslated region (UTR), −52G > A (rs1799946), −44C > G (rs1800972) and −20G > A (rs11362), and two polymorphisms at DEFB1 3′ UTR, c*5G > A (rs1047031) and c*87A > G (rs1800971), were analysed by direct sequencing and correlated with hDB-1 salivary concentration (tested with enzyme-linked immunosorbent assay (ELISA)) in 40 healthy subjects.ResultsSignificant associations were found between individuals presenting different DEFB1 polymorphisms at positions −52 and −44 of the gene and hBD-1 salivary concentrations: −52 G/G carriers had higher levels of protein than G/A and A/A; −44C/G subjects showed a higher protein concentration than homozygous wild-type C/C. For the −20G > A, c*5G > A and c*87A > G polymorphisms, no statistically significant differences were found. Combined haplotype analysis confirmed the results obtained considering the single-nucleotide polymorphisms (SNPs) singularly.ConclusionPolymorphisms in the DEFB1 gene influence hBD-1 production and, therefore, could modify the innate immune system responses and, consequently, the oral health.