The influence of KIR gene presence/absence polymorphisms on the development of periodontal disease in smokers and non-smokers

Introduction: Periodontal diseases are highly prevalent inflammatory, multifactorial diseases. Smoking is one of the most important environmental risk factors for the development and severity of periodontal disease. Killer cell immunoglobulin-like receptors (KIRs) are members of the immunoglobulin (Ig) superfamily and play an essential role in the regulation of NK cell activity, allowing natural killer (NK) cells to sense and respond to human leukocyte antigen (HLA) class I. The aim of this study was to evaluate the influence of KIR gene presence/absence polymorphisms on the development of periodontal disease in smokers and non-smokers. Material and methods: This study enrolled 400 Caucasian subjects (age range 25-69 years) from the West Pomeranian region of Poland. The subjects were categorized into four subgroups (smoking and non-smoking patients with periodontal disease; smoking and non-smoking subjects without periodontal disease-control subjects). Results: The differences of KIR gene frequencies between non-smoking patients and non-smoking control subjects as well as smoking patients and control subjects were not statistically significant. In multi-variate regression analysis advanced age of patients and smoking were independent factors associated with increased frequency of periodontal disease. Conclusions: The results of this study suggest that the main factor associated with increased risk of periodontal disease is smoking, whereas KIR presence/absence polymorphism is not a significant factor involved in the pathogenesis of periodontal disease.