Protein and mRNA expression of interleukin-33 in periodontally diseased and healthy individuals and impact of nonsurgical periodontal therapy in salivary IL-33 levels

BACKGROUND: Interleukin (IL)-33 is a member of IL-1 beta family of cytokines having a pivotal role in bone destruction. However, its role in periodontal disease is not clearly established. The objective of the present study was to evaluate salivary and gingival IL-33 expression in periodontally healthy and diseased individuals. The change in salivary IL-33 after nonsurgical therapy was also analyzed. MATERIALS AND METHODS: Salivary IL-33 concentration was estimated using enzyme-linked immunosorbent assay in periodontally healthy and diseased individuals (30 in each group). Re-evaluation was done in periodontitis patients after 6 weeks of nonsurgical therapy. Further, the messenger ribonucleic acid expression of IL-33 in healthy and diseased gingival tissues was also examined using reverse transcriptase-polymerase chain reaction and correlated with IL-1 beta messenger ribonucleic acid. RESULTS: Salivary IL-33 concentration in periodontitis patients was 1.65 fold higher than healthy controls (P < 0.0001), and 16% reduction was noticed after nonsurgical treatment. Salivary IL-33 concentration could be used to differentiate periodontitis from health at a cutoff value of 543.16 ng/mL with 93.33% sensitivity and 90% specificity (area under the curve 0.92). Upregulated gingival expression of IL-33 was also noted in periodontitis patients, and it was positively correlated with IL-1 beta (r = 0.7). CONCLUSION: The study reconfirms the role of IL-33 in periodontal disease, proposed a threshold value of differentiating healthy and periodontitis patients, and suggests IL-33 as a potential diagnostic biomarker for periodontal disease and to evaluate the response to periodontal therapy.