The effect of smoking on inflammatory cell infiltrate subtypes in gingival tissue of patients with chronic periodontitis

Interaction between beta-3 adrenergic receptor genotype and environmental factors on periodontal progression

OBJECTIVES

The purpose of this longitudinal study was to evaluate the relationship between beta-3 adrenergic receptor polymorphism and environmental factors such as smoking on periodontal disease by considering effect modification.

MATERIALS AND METHODS

A total of 294 subjects who participated in all follow-up surveys over the 6-year study period were analysed. After dividing subjects into tertiles according to the number of years exposed to smoking, we conducted Poisson regression analysis to compare the incidence rate ratio (IRR) for periodontal disease events during the 6-year study period with beta-3 adrenergic receptor genotype (1: Arg allele carriers, 2: Arg allele non-carriers) for each tertile adjusted for other four variables.

RESULTS

The number of years exposed to smoking (mean ± standard deviation) for the 1st, 2nd and 3rd tertiles was 0 ± 0, 20.1 ± 9.1 and 45.3 ± 7.7 years, respectively. The IRRs ± SE were 0.89 ± 0.08 (p = 0.218) for the 1st tertile, 1.93 ± 0.36 (p < 0.001) for the 2nd tertile and 2.56 ± 0.23 (p < 0.001) for the 3rd tertile.

CONCLUSION

There was a clear dose-response relationship between beta-3 adrenergic receptor genotype and periodontal disease progression based on the number of years exposed to smoking.

Importin 8 is involved in human periodontitis by the NF-κB pathway

This study was undertaken to investigate the roles of importin 8 (IPO8) and infiltrating macrophages in human periodontitis. Gingival tissues were collected from 18 male patients with mild and severe periodontitis. IPO8 expression was observed by immunohistochemistry and western blotting. CD68 expression, a marker for macrophages, was observed by immunohistochemistry and immunofluorescence. IPO8 expression in mouse macrophage RAW264.7 cells stimulated by lipopolysaccharide (LPS) purified from Porphyromonas gingivalis was examined in vitro using small interfering RNA (siRNA). Phosphorylation of nuclear factor kappa B (NF)-κB pp65 was detected as an indicator of NF-κB activation by immunofluorescence and western blotting. IPO8 expression was increased in gingival tissues with periodontitis compared with healthy ones, and the elevation rose in proportion to the severity of periodontitis. Similarly, more CD68+ infiltrating macrophages were observed in severe periodontitis tissues. LPS stimulation promoted IPO8 expression in mouse macrophage cells. Knockdown of IPO8 by siRNA alleviated the LPS-induced increases in tumor necrosis factor-α and interleukin-6 gene expression, as well as NF-κB activation, by decreasing the expression of NF-κB pp 65 in the nuclei of cells in vitro. In conclusion, IOP8 plays a role in human periodontitis. Targeted inhibition of IOP8 expression could effectively alleviate periodontal inflammation.