Polymorphisms in the 5′ flanking region of IL12RB2 are associated with susceptibility to periodontal diseases in the Japanese population

Objectives: The expression of interleukin (IL)-12Rβ2 molecule is a crucial regulatory factor in the T-helper type (Th) 1 differentiation of T cells. To elucidate the role of the cell-mediated immune (CMI) response in the pathogenesis of periodontitis, Japanese periodontal patients were subjected to single nucleotide polymorphism (SNP) analyses of the 5′ flanking region of IL12RB2, whose variants are frequently detected in lepromatous leprosy patients, in which the very weak cellular immune response is caused by low expression of IL-12Rβ2. Material and Methods: The gene polymorphisms of the 5′ flanking region of IL12RB2 were examined in subjects with several types of periodontal disease and in healthy controls. Serum immunoglobulin (Ig) G antibody titres against periodontopathic bacteria were measured and compared in periodontal patients with and without variant alleles of IL12RB2. Results: The frequencies of variant alleles of IL12RB2 were significantly higher in aggressive periodontitis patients as compared with healthy controls or chronic periodontitis patients. Serum IgG titres against all periodontal bacteria examined in subjects carrying variant alleles were higher than those in subjects without variant alleles. Conclusion: IL-12Rβ2 SNPs could be useful as genetic markers to access the susceptibility of the general population to periodontal disease. Low CMI responses or high humoral responses are associated with the pathogenesis of inflammatory periodontal diseases.