Evaluation of Inflammasome Gene Polymorphisms in Periodontitis Patients

Innate immune response is the first line of defense mechanism of the body against pathogens. One of the most important proteins involved in the innate immune response are the inflammasomes which are multimeric protein complexes composed of a sensor molecule (the PRR), typically the adapter molecule apoptosis-associated speck-like protein containing a caspase-recruitment domain (CARD), and the protease caspase-1. Different types of inflammasomes have been described. In periodontal disease, inflammasome activation is associated with the release of pro-inflammatory cytokines, which can lead to tissue destruction and periodontal damage.

Progression rate, onset age, and severity of periodontal disease are influenced by some modifiable or non-modifiable risk factors present in the host. Genetic polymorphisms are non-modifiable risk factors for periodontitis. Variations in inflammasome genes may be determinants in the development of periodontal disease by leading to diversity in inflammatory markers.

Sample size is determined based on a previous study which analyzes the effect of NLRP3 gene polymorphism on periodontitis susceptibility. For rs4612666 group, with an α value of 0.05 and a power of 80%, it is determined that there should be 80 participants in each group. Totally 240 patients are included (80 periodontally healthy, 80 Stage III Grade B periodontitis, 80 Stage III Grade C periodontitis). The whole mouth clinical periodontal examination includes measurement of probing depth (PPD), clinical attachment level (CAL), presence of bleeding on probing (BOP), gingival index (GI), and plaque index (PI) at 6 sites per tooth, except the third molars. Periodontal diagnosis of each patient has been made according to the 2017 World Workshop on Classification of Periodontal and Peri-Implant Diseases and Conditions. Healthy group includes individuals without a clinical inflammation pattern and a history of periodontitis, with no detected clinical attachment and bone loss, BOP < 10%, probing depth ≤ 3 mm. Stage III Grade B periodontitis patients have minimum of 20 teeth (except third molars), with CAL ≥ 5 mm, probing depth ≥ 6mm, and radiographically showing bone loss extending up to one-third of the root, percantage of bone lose by age is 0.25-1 and Stage III Grade C patients have minimum of 20 teeth (except third molars), with CAL ≥ 5 mm, probing depth ≥ 6mm, and radiographically showing bone loss extending up to one-third of the root, percantage of bone lose by age is >1.

Sample Collection and DNA Isolation and Genotyping A total of 5 mL of blood is collected from the antecubital fossa by venepuncture method from each participants and stored at -80°C until analysis day. DNA isolation has been made using genomic DNA kits. rs4612666, rs75985579, and rs2793845 SNP regions are detected from DNA material using Real-Time PCR device genotyping kits.

Statistical analysis has been performed with standard statistical software package by selecting appropriate tests.