Análise genotípica e fenotípica de moléculas envolvidas na resposta imune e avaliação do potencial citotóxico em células de indivíduos com diferentes formas clínicas da doença periodontal

Abstract

Periodontal disease is an oral infectious disease caused by pathogenic factors derived from Gram-negative bacteria that lead to destruction of tooth-supporting structures. In addition to the role played by host cells, the contribution of a genetic basis for both the beginning and disease progression is also evident. The overall objective of the current study was to evaluate the genotypic and phenotypic expression of genes involved in the immune response of subjects with periodontal disease. In addition, we aimed to assess the expression of inflammatory cytokines and cytolytic effector molecules from distinct lymphocyte subsets in the peripheral blood of individuals with different clinical forms of periodontal disease (aggressive periodontitisAP and chronic periodontitisCP) as well as health individuals (control group-C). In the genotypic study, the objectives consisted of investigating the occurrence of polymorphisms in CD28, CTLA-4 and IL-10. Moreover, we evaluated possible associations of these polymorphisms with greater or lesser clinical attachment loss in individuals with clinical forms AP and CP. The phenotypic study, on the other hand, aimed to evaluate the expression of costimulatory molecules, CD28 e CTLA-4, in addition to evaluate the cytokine (IFN- and IL-17) and the cytotoxic potential of cell populations by the analysis of expression of cytolytic molecules (granzyme A and perforin) from subjects with no periodontal disease and individuals with different clinical forms of the disease. Peripheral blood cells were stimulated in culture with different LPS (derived from E. coli and P. gingivalis). For the genotypic study scrapings from oral mucosa were collected, whereas for phenotypical study samples of peripheral blood from individuals with the periodontal disease and healthy individuals, according to clinical criteria, were collected. In summary, the results showed: (1) association of the polymorphism T/C at locus +17, CD28 gene with AP in nonsmokers individuals; (2) association of the polymorphism A/G at locus +49, CTLA-4 gene with a higher clinical attachment loss in nonsmokers with AP; (3) lack of association of polymorphisms C/A, -592 locus, C/T, -819 locus and G/A, -1082 locus, IL-10 gene with the different clinical forms, and clinical attachment loss in nonsmokers; (4) multivariate analysis of IL-10 polymorphisms revealed an association between the A+ genotype in the locus -592 (C/A) of IL-10 gene with a greater risk of individuals develop the different clinical forms of periodontal disease, taking smoking into consideration; (5) higher percentage of CD4 + CTLA-4 + T cells in CP group compared to the AP group, the cells being subjected to the stimulation of P. gingivalis, indicating possibly a better controlled response of lymphocytes in individuals CP group; (6) higher frequency of CD8 +T cells expressing IFN- , in subjects with AP when grown with P. gingivalis compared to cells in the absence of stimulation; (7) an increase in total production of IL-17 by lymphocytes from individuals with CP; when stimulated with P. gingivalis in relation to stimulation with E. coli, probably related to the use of periodontopathogenic bacteria LPS more associated with the CP; (8) increased frequency of CD4 -CD8 -IL17 + in individuals with AP and CP, when challenged with P. gingivalis compared to stimulation with E. coli, indicating a hyper-reactivity potential of these cells; (9) lower contribution of CD4 + T cells to produce IL-17, when subjected to stimulation with P. gingivalis compared to E. coli; (10) increased frequency of CD4 -CD8-Granzyme A+ in CP group than in group C, in all culture conditions, indicating a potential role for these cells in the pathogenesis of CP; (11) increase in the frequency of cells CD4 -CD8 -perforin + in CP group, when compared to groups C and AP, in every culture conditions, suggesting a role in the pathogenesis of CP, (12) CD4-CD8-are the main producers of perforin, in groups C, AP and CP, when grown with P. gingivalis compared to those cultured with E. coli, reinforcing the presence of varied responses to different stimuli of LPS. Taken together, these data highlight the importance of assessing genetic polymorphisms that may assist in establishing risk groups, while pointing to cell populations potentially involved in the pathogenesis of periodontal disease. Among our results, we highlight the CD4 -CD8-cells whose expression of cytokines and cytotoxic molecules was evident. These data demonstrate the clear importance to identify and characterize these cells.