Evaluation of IL-40, IL-1β, and MMP-8 levels in saliva samples of individuals with periodontal health and periodontal disease

Objective: The objective of this study was to determine the levels of interleukin-40 (IL-40), interleukin-1 beta (IL-1β), and matrix metalloproteinase (MMP)-8 in saliva samples of individuals with periodontally healthy and periodontally diseased conditions, to compare the levels between groups, and to evaluate the relationship between these cytokines and periodontal clinical parameters. Methods: Saliva samples were collected from 120 systemically healthy, non-smoking individuals (40 healthy [S], 40 with gingivitis [G], and 40 with periodontitis [P]). Clinical parameters, including plaque index (PI), gingival index (GI), pocket depth at probing (PD), clinical attachment loss (CAL), and bleeding on probing (BOP), were measured. Unstimulated saliva samples were collected from all individuals, and IL-40, IL-1β, and MMP-8 levels in the collected saliva samples were determined by enzyme-linked immunosorbent assay (ELISA). The obtained data were analyzed using SPSS 28.0 software. Results: Salivary IL-40 levels were significantly higher in the G group than in the S group (p<0.05), while no significant difference was observed between the other groups (p>0.05). There was a significant positive correlation between salivary IL-40 levels and PD, CAL, BOP, and IL-1β and MMP-8 values (p<0.05). IL-1β levels were significantly higher in the P group than in the S and G groups (p<0.05) and in the G group than in the S group (p<0.05). A significant correlation was observed between IL-1β and MMP-8 levels and clinical parameters (p<0.05). Salivary MMP-8 levels were significantly higher in the P group than in the S group (p<0.05), while no significant difference was observed between the S and P groups in the G group (p>0.05). Conclusion: Based on our study, we concluded that IL-40 and IL-1β may serve as effective salivary biomarkers for the diagnosis of gingivitis, while MMP-8 and IL-1β may be effective for the differentiation of periodontitis. We also hypothesize that IL-40 may play a role in the pathogenesis of periodontal disease, similar to IL-1β and MMP-8, and further large-scale cohort studies are needed to elucidate its possible role, as there is currently limited scientific data on this cytokine. e.Keywords: periodontitis, saliva, IL-40, IL-1β, MMP-8.