Evaluation of TNF-α, IL-17A, and YKL-40 in GCF and Serum of Psoriasis Patients and Healthy Controls

Psoriasis and periodontitis are chronic inflammatory diseases that share key immunopathological mechanisms. Psoriasis is primarily a dermatological condition, but it also exhibits systemic inflammatory characteristics that may contribute to comorbidities such as periodontitis. Periodontitis, a chronic immune-inflammatory condition of the supporting structures of the teeth, is similarly characterized by sustained inflammatory responses and tissue destruction. Emerging evidence suggests that these two diseases may be biologically linked through shared inflammatory pathways. Among the common mediators, tumor necrosis factor-alpha (TNF-α), interleukin-17A (IL-17A), and YKL-40 play prominent roles in the pathogenesis of both conditions. TNF-α contributes to immune activation, tissue breakdown, and bone resorption. IL-17A, associated with Th17-mediated responses, promotes keratinocyte proliferation and inflammatory cell infiltration in psoriasis, while driving extracellular matrix degradation and osteoclastogenesis in periodontitis. YKL-40, a glycoprotein involved in tissue remodeling and inflammation, has been proposed as a potential biomarker for chronic inflammatory diseases, including psoriasis and periodontitis. While elevated levels of these markers have been individually observed in serum or tissues of patients with either condition, limited data exist on their expression in both systemic and local environments-particularly within the gingival crevicular fluid (GCF) of psoriasis patients. This study will address this gap by assessing TNF-α, IL-17A, and YKL-40 levels in GCF and serum samples of individuals with and without psoriasis and periodontal disease. Through a cross-sectional, case-control study design, this research aims to investigate whether systemic inflammation associated with psoriasis correlates with increased periodontal inflammation and whether common biomarkers may indicate a shared pathogenic mechanism. Understanding this potential link could lead to improved interdisciplinary management strategies and earlier identification of periodontal risk in patients with psoriasis.