Porphyromonas gingivalis HmuY-induced production of interleukin-6 and IL-6 polymorphism in chronic periodontitis.

Background: In chronic periodontitis (CP), the gene polymorphism of interleukin-6 (IL-6) to 174C/G has been associated with the altered production of this cytokine. The aim of this pilot study is to compare the allelic and genotypic frequencies in patients with CP with control individuals without periodontitis (NP) and to measure the production of IL-6 by whole blood cells stimulated with Porphyromonas gingivalis HmuY protein.

Methods: DNA was isolated from peripheral blood cells of 49 patients with CP and 60 control individuals classified as NP, and genotyping was performed by polymerase chain reaction using sequence-specific primers. Whole blood cells from 29 patients with CP and 30 control individuals were stimulated for 48 hours with HmuY, and IL-6 levels were measured using enzyme-linked immunosorbent assay.

Results: The proportion of individuals carrying the G allele at position -174 of the IL-6 gene was higher in the group with CP (85.7%) than in the normal control group (73.3%; P <0.03). P. gingivalis HmuY-induced production of IL-6 was higher in the group with CP (P <0.05).

Conclusions: Our findings suggest that P. gingivalis HmuY may be associated with increased IL-6 production during CP. Furthermore, patients with periodontitis and individuals with higher HmuY-induced production of IL-6 show a high frequency of the G allele at position -174.