Genotypes and systemic inflammatory molecules in experimental gingivitis

Objectives: Genotypes play an important role in susceptibility to certain diseases. Specific polymorphisms on Toll-like receptor - 4 (TLR4 Asp299Gly), and in the IL-1 gene cluster (IL-1A+4845 and IL-1B+3954) have been reported to modify inflammatory diseases. This study aimed to investigate the influence of single nucleotide polymorphisms (SNPs) for IL-1A+4845, IL-1B+3954 and TLR4 Asp299Gly on progression of experimental gingivitis. Methods: A total of 172 subjects were included in this study. Modified Gingival Index (MGI) was recorded at baseline and after 21 days without toothbrushing. Genomic DNA was obtained from whole blood and genotyped for the Asp299Gly TLR4 polymorphism using Allelic Discrimination by Real Time Polymerase Chain Reaction (PCR). IL-1A+4835 and IL-1B+3954 SNPs were genotyped by PCR and Restriction Fragment Length Polymorphism (RFLP). Plasma was obtained from peripheral blood and the protein levels of C-Reactive Protein (CRP), soluble Intercellular Adhesion Molecule-1 (sICAM-1), and Interleukin-8 (IL-8) were measured by ELISA and Luminex. Results: The TLR4 Asp299Gly, IL-1A+4845 and IL-1B+3954 polymorphisms were found in 8.14%, 91.30% and 34.78% of subjects, respectively. MGI significantly increased after 21 days in all subjects (P<0.01), but there was no significant difference between subjects with or without the three SNPs. Subjects with TLR4Asp299Gly polymorphism showed declined level of CRP and IL-8 whereas subjects with IL-1A+4845 homozygous for allele G (8.70%) and IL-1B+3954 homozygous for allele T (2.17%) displayed reduced levels of sICAM-1 and IL-8. Conclusion: The experimental gingivitis study revealed that TLR4 Asp299Gly, IL-1A+4845 and IL-1B+3954 polymorphism have no clinical influence on gingival inflammation. However, carriers of TLR4 Asp299Gly polymorphism, IL-1A+4845 allele G homozygote and IL-1B+3954 allele T homozygote were associated with decreased levels of the cytokine, IL-8 and the inflammatory molecules, CRP and sICAM.

Supported by grant DE017384 from NIDCR