Immunohistochemical evaluation of nucleotide-binding and oligomerization domain 1 and nucleotide-binding and oligomerization domain 2 receptors in periodontal health and disease

Abstract

Introduction: Periodontal disease, infectious in origin and inflammatory in progression ultimately leads to destruction of periodontium. Pattern recognition receptors (PRRs) help in identifying the molecular patterns displayed on the bacteria and mount an immune response. Nucleotide-binding and oligomerization domain receptors (NOD1 and NOD2) are cytosolic PRRs involved in the immunopathogenic process involved in the periodontal diseases. This study was undertaken to evaluate distribution of NOD1 and NOD2 and to compare and correlate the NOD1 and NOD2 expression in gingival samples from healthy, chronic, and aggressive periodontitis participants. Materials and Methods: Sixty participants participated in the study and were divided into three groups of 20 individuals each - Group I (healthy), Group II (chronic periodontitis), and Group III (aggressive periodontitis) based on the inclusion and exclusion criteria. Gingival tissue samples were collected during periodontal flap surgery, crown lengthening procedure in periodontitis individuals and healthy controls, respectively. The levels of NOD1 and NOD2 in the gingival samples were analyzed using immunohistochemistry. Results: The NOD1 and NOD2 levels were higher in Group III (aggressive periodontitis) followed by Group II (chronic periodontitis) and lowest in Group I (healthy). Comparison of mean NOD1 and NOD2 between the three Groups showed statistically significant difference (P < 0.001). Positive correlation was observed on correlating NOD1 and NOD2 with the clinical parameters (gingival index, probing pocket depth, and clinical attachment loss). Conclusion: Epithelial localization of NOD1 and NOD2 was more in periodontitis than in healthy tissue. These findings indicate that NOD1 and NOD2 play an indispensable role at the forefront in innate immunity.