Evaluation of TNF-α, IL-17A, and YKL-40 levels in gingival crevicular fluid and serum of psoriasis patients

Objective: Periodontitis is a chronic inflammatory disease characterized by the progressive destruction of tissues surrounding the teeth, while psoriasis is a chronic immune-mediated inflammatory disease that leads to plaque formation on the skin. Both diseases are associated with immune system overactivation and increased levels of inflammatory cytokines. These shared mechanisms may trigger or exacerbate each other due to immune dysregulation. The aim of this study is to evaluate periodontal conditions in individuals with psoriasis and systemically healthy individuals, and to compare the levels of TNF-α, IL-17A, and YKL-40 in their gingival crevicular fluid (GCF) and serum. Additionally, the study aims to determine the relationship between these biomarkers and the severity of periodontal disease. Method: A total of 100 participants were included in the study and divided into five groups: healthy individuals (S), control gingivitis (G), control periodontitis (P), psoriasis with gingivitis (PS+G), and psoriasis with periodontitis (PS+P). GCF and serum samples were collected from all participants, and the levels of TNF-α, IL-17A, and YKL-40 were analyzed using the ELISA method. Periodontal health status was assessed using plaque index (PI), bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment level (CAL) measurements. Results: GCF TNF-α levels were significantly higher in the periodontitis groups (P, PS+P) compared to healthy individuals (p<0.05). However, no significant difference was found between the P and PS+P groups regarding GCF TNF-α levels. Serum TNF-α levels in the psoriasis groups (PS+G, PS+P) were significantly higher compared to systemically healthy groups (S, G, P). In the periodontitis groups (P and PS+P), both GCF and serum IL-17A levels were significantly higher than in healthy individuals (p<0.05). However, GCF IL-17A levels in the psoriasis groups (PS+G and PS+P) were similar to those in healthy individuals, and no statistically significant difference was observed between these groups (p>0.05). Serum IL-17A levels in the psoriasis groups (PS+G, PS+P) were significantly higher compared to systemically healthy groups (S, G, P). In the periodontitis groups (P and PS+P), GCF and serum YKL-40 levels were significantly higher than in healthy individuals (p<0.05). No significant difference was found in serum YKL-40 levels between the psoriasis groups and the healthy control groups (p>0.05). Plaque index (PI), bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment level (CAL) values were highest in the psoriasis periodontitis (PS+P) group. Healthy individuals (S) had the lowest values for all clinical parameters. Conclusion: The study revealed that the prevalence of periodontal disease is higher in individuals with psoriasis and that inflammatory markers such as TNF-α, IL-17A, and YKL-40 play a common role in the pathogenesis of both diseases. In periodontitis patients, the levels of these biomarkers in GCF and serum were significantly elevated. The presence of periodontitis in individuals with psoriasis exacerbates inflammation and leads to increased tissue destruction in the periodontal tissues. Routine periodontal examination and treatment in psoriasis patients may help control systemic inflammation more effectively. Keywords: Psoriasis, Periodontitis, Gingival Crevicular Fluid, TNF-α, IL-17A, YKL-40.