IL-4 and IL-13 Polymorphisms in Periodontitis-Resistant Subjects

Objectives: Interleukin (IL)-4 and IL-13 have been studied in association with periodontitis. The resistance to periodontitis in elderly individuals who show minimum periodontal tissue destruction may be explained by genetic factors related to the host immune response. The aim of this study was to analyse IL-4 and IL-13 polymorphisms in older, north European subjects with no signs of periodontitis (O) in comparison with young controls (C) and patients with aggressive periodontitis (AP). Methods: 430 subjects (age ≥55) were screened for having no sites with radiographic bone loss in the dentition (≥20 teeth). 22 patients met the clinical and radiographic criteria for the O group. In the groups of AP (n=29) and C (n=35) patients, only subjects under the age of 35 were included. Venous blood was collected and DNA prepared. The following SNPs were analysed by means of PCR and RFLP: a C(-590)-T in the IL-4 promoter, a VNTR in IL-4 intron 2, a C(-1112)-T in the IL-13 promoter, and a G(+2044)-A in IL-13 exon 4. The genotype frequencies in the groups were tested (Mann-Whitney U, α-level of 5%). Results: The frequencies of the genotypes of both genes were different in the three groups. The SNP in the IL-4 promoter could not be detected in the O group. Moreover, the distribution of the IL-4 genotypes was significantly different in the O group in comparison with the AP and the C groups (p <0.0001). Similar results were shown for the VNTR in the IL-4 intron 2. Conversely, the frequency of the IL-13 SNP was higher in the O and C subjects than in the AP group (p <0.05). Conclusions: The results indicate an antagonism between IL-4 and IL-13 SNPs. The IL-4 allele C may be associated with resistance to periodontitis. Further studies with larger samples are necessary to confirm these data.