Expression of NLRP3 and superoxide dismutase-2 (SOD2) in the gingival tissues of periodontitis patients with and without type 2 diabetes mellitus: a case–control study

Objective

To evaluate the interaction between the NLRP3 inflammasome and superoxide dismutase-2 (SOD2) to provide an insight into the complex host response in periodontitis patients with type 2 diabetes mellitus (T2DM), who have an inherent upregulation of inflammatory cytokines and reactive oxygen species (ROS).

Methods

Gingival tissues were collected from 51 patients divided into three groups: group 1, systemically and periodontally healthy; group 2, systemically healthy with periodontitis; and group 3, periodontitis with T2DM. Immunohistochemistry was performed to evaluate the expression of the NLRP3 inflammasome and SOD2 in terms of mean percentage, intensity and staining intensity distribution (SID).

Results

The mean percentage levels of NLRP3 and SOD2 expression were statistically significantly higher in group 3 (49.16 ± 6.45% and 48.22 ± 11.66%, respectively) when compared to groups 2 and 1 (p < 0.001). While the groups with periodontitis with or without T2DM had statistically significant differences in these variables, the highest expression was found in the periodontitis patient group with T2DM (p < 0.001). NLRP3 and SOD2 mean percentages were positively correlated in groups 1 and 2 but were negatively correlated in group 3.

Conclusion

NLRP3 inflammasome is significantly upregulated in periodontitis patients with T2DM. The negative correlation between SOD2 and NLRP3 in periodontitis patients with T2DM probably indicates insufficient endogenous SOD2 to effectively counteract the excessive oxidative burden and inflammatory state, thereby compounding periodontal destruction in cohorts with T2DM. Further, NLRP3 and SOD2 can be used as biomarkers of periodontal disease progression in periodontitis cohorts modified by DM.