Variation in the CXCR1 gene (IL8RA) is not associated with susceptibility to chronic periodontitis.

BACKGROUND: The chemokine receptor 1 CXCR-1 (or IL8R-alpha) is a specific receptor for the interleukin 8 (IL-8), which is chemoattractant for neutrophils and has an important role in the inflammatory response. The polymorphism rs2234671 at position Ex2+860G>C of the CXCR1 gene causes a conservative amino acid substitution (S276T). This single nucleotide polymorphism (SNP) seemed to be functional as it was associated with decreased lung cancer risk. Previous studies of our group found association of haplotypes in the IL8 and in the CXCR2 genes with the multifactorial disease chronic periodontitis. In this study we investigated the polymorphism rs2234671 in 395 Brazilian subjects with and without chronic periodontitis. FINDINGS: Similar distribution of the allelic and genotypic frequencies were observed between the groups (p>0.05). CONCLUSIONS: The polymorphism rs2234671 in the CXCR1 gene was not associated with the susceptibility to chronic periodontitis in the studied Brazilian population.

Association of haplotypes in the CXCR2 gene with periodontitis in a Brazilian population.

CXCR-2 is a receptor of interleukin-8, which is involved in acute and chronic inflammatory processes. Polymorphisms in the CXCR2 gene have been associated with chronic inflammatory conditions. The aim of this study was to investigate whether the +785(C/T), +1208(T/C), and +1440(G/A) single-nucleotide polymorphisms (SNPs) in the CXCR2 gene, as well as their haplotypes, are associated with susceptibility to periodontitis in Brazilians. DNA was extracted from the buccal epithelial cells of 487 individuals (control = 215; periodontitis = 272). The SNPs were investigated using the sequence-specific primer-polymerase chain reaction method. Associations between the polymorphisms and subject phenotypes were analyzed using the chi-squared statistical test, followed by univariate and multivariate logistic regression modeling. Haplotypes were reconstructed using the expectation-maximization algorithm, and differences in haplotype distribution between the groups were analyzed to estimate genetic susceptibility for periodontitis development. Univariate and multivariate analysis revealed that age, skin color, and smoking status were associated with periodontitis. The +1440 GG genotype was shown to be protective against periodontitis in both univariate and multivariate analysis (odds ratio [OR](adjusted) = 0.42; 95% confidence interval [CI] = 0.19, 0.96). A similar relevant result for the +1440 GG was obtained in an alternative analysis considering a subgroup containing only white nonsmokers (OR = 0.37; 95% CI = 0.15, 0.92). White nonsmokers with the CTG/TCG haplotype appeared to be genetically protected against the development of periodontitis (OR = 0.29; 95% CI = 0.09, 0.89), while those carrying the CTG/TCA haplotype were more susceptible to the development of periodontitis (OR = 2.08; 95% CI = 1.24, 3.51). In conclusion, the +1440 SNP and some haplotypes are associated with periodontitis in Brazilian individuals.

Detection of the single nucleotide polymorphism (rs2227307) in the human interleukin 8 gene using a different PCR-RFLP assay / Detecção do polimorfismo de base única (rs2227307) no gene interleucina 8 humano usando PCR-RFLP

Interleukin 8 (IL-8) is a chemokine that acts as a potent chemoattractant for neutrophils. Single nucleotide polymorphisms (SNPs) in the human IL8 gene have been investigated in many disease association studies. We have developed a different PCR-RFLP (Polymerase Chain Reaction - Restriction Fragment of Length Polymorphism) assay for genotyping the SNP (rs2227307) in the IL8 gene. This method was used for typing 147 white healthy Brazilian individuals, whose DNA was obtained from buccal epithelial cells and extracted with phenol: chloroform: isoamyl alcohol. Genomic DNA was amplified by PCR using a conventional thermal cycler. The PCR products (573 bp) were submitted to RFLP reactions. The RFLP fragments were analyzed in a 4% agarose gel stained with ethidium bromide. The genotype distribution observed in this study was consistent with the assumption of Hardy-Weinberg equilibrium and was similar (p=0.30) to those reported for other white populations in the SNP Database of the National Center for Biotechnology Information (NCBI). Because the PCR-RFLP method presented here was efficient, low cost, reproducible and convenient for laboratories with a limited level of technology worldwide, it should be useful for genotyping in case-control association or population genetic studies.

A Interleucina 8 é uma quimiocina com potente ação quimioatrativa para neutrófilos. Polimorfismos de base única (SNPs) no gene humano IL8 têm sido investigados em vários estudos de associação com doenças. Um método diferente de PCR-RFLP para genotipagem do SNP (rs2227307) do gene IL8 foi desenvolvido pelo nosso grupo. Esse método foi utilizado para genotipar 147 indivíduos brasileiros brancos saudáveis que tiveram seu DNA obtido de células da mucosa oral e extraído com fenol:clorofórmio:álcool isoamílico. DNA genômico foi amplificado por PCR usando um termociclador convencional, e a seguir os produtos da PCR (573 pb) foram submetidos a reações de RFLP. Os produtos de RFLP foram analisados em gel de agarose 4% impregnado com brometo de etídio. A distribuição do genótipo observado neste estudo foi consistente com o equilíbrio de Hardy-Weinberg e foi similar (p=0,30) ao reportado em outras populações brancas no banco de dados de SNPs do National Center for Biotechnology Information (NCBI). Este novo método de PCR-RFLP apresentado neste estudo foi eficiente, de baixo custo, reprodutível e conveniente para laboratórios com tecnologia limitada, podendo ser útil para utilização em estudos de genética de populações ou de associação com doenças (tipo caso-controle).