Effects of smoking on the salivary and GCF levels of IL-17 and IL-35 in periodontitis

Periodontitis progression is associated with a host response in which anti-inflammatory and pro-inflammatory cytokine networks play a key role. Smoking is involved in the production of various mediators. The study aims to evaluate the levels of IL-17 and IL-35 in saliva and gingival crevicular fluid (GCF), to investigate the effects of smoking on these cytokines in smoker and non-smoker periodontitis patients. 19 smokers with periodontitis, 20 non-smokers with periodontitis, and 18 periodontally healthy subjects were included in the study. Periodontal clinical indexes were recorded and the levels of IL-17 and IL-35 in saliva and GCF were analyzed. No significant difference was detected among the groups in terms of salivary IL-17 and IL-35 levels. GCF IL-17 and IL-35 concentration levels in the non-smoker periodontitis group were significantly lower than the others (p < 0.05). Total levels of GCF IL-17 were significantly higher in both periodontitis groups than the control group; and total levels of GCF IL-35 were significantly higher in non-smoker periodontitis group than the others (p < 0.05). A positive correlation was detected between the salivary IL-17 and IL-35 levels (r = 0.884), GCF IL-17 and IL-35 concentrations (r = 0.854), and total GCF IL-17 and IL-35 (r = 0.973) levels (p < 0.01). The present study revealed a positive correlation between the IL-35 and IL-17 levels both in saliva and GCF. IL-17 and IL-35 can be considered as one of the cytokines that play a role in periodontal health and periodontitis; and smoking may be among the factors that affect the levels of these cytokines in GCF and saliva.