Levels of interleukin‐37 in gingival crevicular fluid, saliva, or plasma in periodontal disease

Abstract

The aim of this study was to compare the levels of levels of interleukin-37 (IL-37) in gingival crevicular fluid, saliva and plasma in patients with periodontal disease and patients with healthy periodontium and to correlate these levels with clinical parameters. Samples of gingival crevicular fluid, whole saliva and plasma were collected from systemically healthy, nonsmoker periodontally healthy controls (group 1, n=20), gingivitis patients (group 2, n=20) and chronic periodontitis patients (group 3, n=20). Full-mouth clinical periodontal parameters, including probing depth, plaque index, gingival index and bleeding on probing, were also recorded. IL-37 levels in the biofluid samples were determined by ELISA. Data were tested statistically using the Kruskal-Wallis test followed by the Mann-Whitney U-test. The concentration of IL-37 in gingival crevicular fluid was significantly lower in group 3 than in groups 1 and 2 (p=0.001), whereas the total amounts in gingival crevicular fluid samples were similar (p>0.05). The salivary and plasma concentrations of IL-37 were similar in the study groups (p>0.05). There were negative correlations between gingival crevicular fluid IL-37 concentrations and gingival crevicular fluid volume in all groups (p<0.05). There was also a negative correlation between the gingival crevicular fluid IL-37 concentration and gingival index in group 3 (p<0.05). IL-37 was expressed in all biofluids. According to our findings, the total amount of IL-37 in gingival crevicular fluid, or salivary or plasma concentrations of IL-37, may not be useful diagnostic markers to differentiate periodontal disease and the periodontally healthy condition. The difference in gingival crevicular fluid IL-37 concentration between the study groups may be a result of the variation in gingival crevicular fluid volume, as suggested by the negative correlation between gingival crevicular fluid volume and gingival crevicular fluid IL-37 concentration. In the light of our findings, it seems that IL-37 is not involved in periodontal disease. Further comprehensive studies may clarify this issue more clearly.