Investigating multifactorial periodontal disease: comparison of clinical and immunological data between genetically susceptible and not susceptible individuals to Periodontitis

Abstract

Currently, periodontal disease (PD) is considered a major cause of dental morbidity in the world. The PD is a multifactorial character, with the influence of factors such as the presence of periodontopathogenic microorganisms, genetic susceptibility of the host, reaction of the immune system, smoking habits, stress and the presence of systemic diseases. The inflamed periodontal tissues demonstrate high concentration of T lymphocytes and macrophages, which produce various cytokines. An important cytokine that has been investigated in PD is interleukin 4 (IL-4), but the obtained results regarding polymorphisms in the IL4 gene and the cytokine levels seemed to be contradictory. There are three polymorphisms in the IL4 gene, the -590, +33, and 70 bp (Deletion / Insertion), which are in linkage disequilibrium, thus forming haplotypes. Haplotypes in the IL4 gene have been associated with inflammatory and autoimmune diseases.A recent study conducted in the Scientific Initiation project of a student named Giovana Anovazzi (FAPESP, Process 2007/05606-3, IC Grant) showed significant association in three IL4 gene polymorphisms. Moreover, individuals with a determined haplotype shown to be 5 times more susceptible to PD (Odds Ratioadjusted = 5.3, 95% Confidence Interval = 2,2-12,9), while others were with a significant probability of not developing the disease (ORadjusted = 0.18, 95% CI = 0,04-0,88). All the results remained significant even after the adjustment for age, gender, skin color and smoking habits (results submitted for publication). As an extension of the previous study, the purpose of this study is to investigate whether between genetically susceptible individuals to the development of PD compared with the non-susceptible ones; there were differences in the levels of IL-4. The present study also seeks to verify whether the individual genetic character (susceptibility) and the levels of cytokine have an influence on the response to periodontal treatment. Thus, it will be examined whether the clinical and immunological data support or not the genetic results previously observed in the same patients. Eighty patients will be contacted to make new periodontal exams and have their gingival fluid collected before and after 45 days of periodontal treatment. The cytokine IL-4 will be quantified by ELISA. This study is expected to contribute to better understanding the multifactorial nature of the periodontal disease, evaluating in this sense the possible inter-relation between the different factors involved in the pathogenesis of the disease.