The pathogenesis of periodontitis (PD) involves several molecules of the immune system that interact in a network to eliminate the periodontopathogens, yet, they contribute to periodontal tissue destruction. The different mechanisms that lead to periodontal tissue damage are not clear. Despite this, immune response genes have been related to the development of PD previously, such as those involved in inflammasomes which are multiprotein complexes and cytokines including Interleukin-1. The aim of the study was to evaluate the polymorphisms in NLRP3 inflammasome, cytokine and receptor of cytokines genes in the development of periodontitis. This case-control study was conducted in 186 patients with PD (stage II and III and grade B) and 208 controls (localized gingivitis and periodontally healthy individuals). Genotyping was performed using PCR-RFLP for the SNP rs4612666 in NLRP3 and using PCR-SSP for IL1A,

The aim of this study was to determine the allele and haplotype frequencies of HLA-A, -B, -DRB1, and -DQB1 in a self-declared White population from the north and northwestern state of Paraná, southern Brazil, and compare the data with populations worldwide. The genotyping was performed with a group of 641 individuals, based on PCR-SSO and -SSP methods, and allele and haplotype frequencies were estimated. Comparisons with European, African, Asian, and Amerindian populations were performed. The most frequent allelic groups, alleles and haplotypes were: HLA-A*02, HLA-B*35, HLA-DRB1*07:01, HLA-DQB1*03:01, and HLA-A*01/B*08/DRB1*03:01. The results reinforced a predominance of a European composition in the self-declared White population from the north and northwestern Paraná.

The pathogenesis of periodontitis involves a complex interaction between the microbial challenge and the host immune response. The individual immunoinflammatory response has a great contribution in the pathogenesis of the disease and becomes a trigger in the process of bone remodeling which is a characteristic of the disease. Thus, the aim of this study was to evaluate the influence of the TLR4 A896G (rs4986790), TLR4 C1196T (rs4986791), CD14 C-260T (rs2569190), RANKL (TNFSF11, rs2277438), and OPG (TNFSF11B C163T, rs3102735) polymorphisms in periodontitis. A case-control study was conducted on patients with periodontitis (N=203) and controls (N=213) over 30 years of age, without diabetes mellitus, acute infections, and osteoarthritis, and patients without aggressive periodontitis, i.e., stage IV and C degree of periodontitis, and any periodontal treatment performed in the last 6 months. Genotypes were determined by the PCR-RFLP and sequencing method. The frequency comparisons between case and controls were performed using the chi-square test and logistic regression (OpenEpi and SNPStats software). The risk (OR) was evaluated for values of P<0.05. Differences in TLR4, CD14, RANKL, and OPG genotype and allele frequency distributions were not observed between patients and controls. However, some variants were a risk factor for the development of periodontitis when considering gender and smoking habits. The TLR4 896 A/G genotype was a risk factor for periodontitis in males (OR=2.86), and the TLR4 1196C/C genotype was a risk factor for nonsmoking males (OR=1.85) when compared to women. The RANKL A/A and the OPG T/C genotype was associated with the risk of the disease in nonsmoking men compared to nonsmoking women with the same genotype (OR=1.96 and OR=2.9, respectively). In conclusion, TLR4, CD14, RANKL, and OPG variants were not associated with periodontitis. However, TLR4, RANKL, and OPG polymorphisms could be a risk for periodontitis in males regardless of smoking habits.

Genetic variations contribute to the susceptibility in the development of periodontitis. The aim of this study was to investigate the influence of IL18, IL12, and MMP9 polymorphisms in the chronic periodontitis. This case-control study involved 381 individuals matched by gender and age. Genotyping of IL18 (rs187238 and rs1946518) and IL12B (rs3212227) was performed by PCR-SSP and PCR-RFLP was used for MMP9 (rs3918242). IL-18 and MMP-9 were quantified in the serum by ELISA. SNPStats and OpenEpi software were used for statistical analysis and, in order to eliminate smoking as a confounding factor, the analyses were also performed in nonsmoking subjects. The IL18-137G/C genotype was associated with the risk of chronic periodontitis in nonsmokers (Pc=0.03; OR=1.99; overdominant inherence model). In the multivariate analyses, homozygous IL18-137G/G and IL18-607C/C were more frequent in males compared to women with these same genotypes (OR=2.51 and OR=3.30, respectively). The serum levels of the IL-18 in patients were higher than those in healthy controls (P=0.005). IL12B and MMP9 polymorphisms and MMP-9 serum concentration were similar in patients and controls. In this study, IL18 was associated with chronic periodontitis susceptibility. Men had greater risk than women for developing the disease when IL18 polymorphism was considered and the susceptibility was independent of the smoking status.

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