Análise de poliomorfismo genético e metilação no promotor do gene Interleucina-8 em pacientes com periodontite cronica e agressiva / Genetic polymorphism and methylation analysis in the promoter region of the Interleukin8 gene in the patients with chronic and aggressive periodontis

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

18/02/2010

RESUMO

Periodontitis is a complex and multifactorial disease that results from the interaction of the host defense mechanisms with the plaque microorganism. Studies of animals and humans indicate that genetic factors could impair inflammatory and immune responses in general, affecting periodontitis experience specifically. Constitutively produced by the epithelial cells, the Interleukin-8 (IL-8) chemokine is important in the regulation of the inflammatory response for its ability to mediate the activation and migration of neutrophils. Therefore, the aim was to investigate the epigenetic (methylation) and genetic (polymorphism) aspects and RNA expression of the IL8 gene promoter in chronic and aggressive periodontitis patients. The first chapter investigated the association of the single-nucleotide polymorphism (SNP) rs4073 and chronic periodontitis; in addition, the levels of IL-8 mRNA in gingival tissue were observed. The IL8 SNP rs4370 was detected and analyzed by PCR-RFLP assay in 289 genomic DNA samples of control (108) and generalized chronic periodontitis (181); analyses were adjusted by the multivariate logistic regression modeling. Total RNA from gingival cells was isolated (12 control subjects x 12 periodontitis patients) and real-time PCR performance was used to detect the levels of IL-8 mRNA. Analysis points to a statistical significant association of the generalized chronic periodontitis with TA genotype (p=4.78x10-3) and age (p=4.32x10-7); moreover, the results showed an increase in the frequency of the A allele in the diseased group. Farther, the higher levels of the IL-8 mRNA were found in the chronic PD group, mainly in individuals who presented the TA genotype; the difference amongst the groups was statistically significant (p=0.03). The IL8 SNP rs4073 is associated with generalized chronic periodontitis in non-smoker Brazilian subjects, since it was observed an increase in the production of IL-8 mRNA transcripts, in the presence of the periodontal inflammation. Importantly, this significance was preserved even after correcting for factors such as age, gender and ethnicity. The second chapter investigated the frequency and the transmission pattern of the A allele of the IL8 SNP rs4370 within Brazilian families affected with generalized aggressive. The polymorphism was detected and analyzed by PCR-RFLP assay in 13 nuclear families. The statistical analysis was performed using the transmission disequilibrium test (TDT). There was no statistically significant association of the IL8 SNP rs4370 with generalized aggressive periodontitis, with a balanced transmission between the alleles (allele T: Z=1.213, p=0.2252; allele A: Z=-1.213, p=0.2252). In addition, there is also similar allele frequency (allele T: 52% and allele A: 48%). The transmission pattern of the A allele and its genotype combination are balanced, in generalized aggressive individuals and in the control subjects. The third chapter aimed to observe the DNA methylation status in the IL8 gene promoter in cells of the oral epithelium of control subjects and to compare it with that of subjects affected by generalized aggressive periodontitis. Genomic DNA from epithelial oral cells of 37 generalized aggressive periodontitis patients and 37 controls were purified, modified by sodium bisulphite and submitted by PCR-MSP technique. Subjects who presented generalized aggressive periodontitis had a higher frequency of hypomethylation of the IL8 gene promoter than those controls (86.5% in the generalized aggressive periodontitis group versus 62% in the control group; p=0.016; ?2 test). The frequency of the individuals in the control group who presented only the unmethylated status was about 62%, while there was an increase in this frequency in the generalized aggressive periodontitis group to 86.5%. It was found a marked hypomethylated status in the subjects who presented generalized aggressive periodontitis, comparing to the controls, in the promoter region analyzed of the IL8 gene

ASSUNTO(S)

inflamação inflammation

ACESSO AO ARTIGO

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