Abstract
INTRODUCTION: Osteoarthritis (OA) of the knee is a prevalent degenerative condition influenced by inflammatory processes. Vitamin D possesses immunomodulatory properties that could potentially impact cytokine expression, notably interleukin (IL)-6 and -10, in osteoarthritic pathology. This study investigates the correlation between serum vitamin D (25-hydroxyvitamin D(3)) levels and serum concentrations of pro-inflammatory cytokine IL-6 and anti-inflammatory cytokine IL-10 among patients with primary knee OA. MATERIAL AND METHODS: This cross-sectional observational study included 80 patients aged above 45 years diagnosed with primary knee OA confirmed radiologically (Kellgren-Lawrence grading). Participants underwent serum analysis for vitamin D(3), IL-6, and IL-10. Clinical severity was assessed through the Visual Analog Scale (VAS) for pain and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) for functional impairment. Data analysis employed Pearson correlation and analysis of variance. RESULTS: Mean serum vitamin D(3) was 27.9 ± 12.2 ng/mL. IL-6 showed significant elevation in vitamin D-deficient patients (128.2 ± 142.5 pg/mL) compared to vitamin D-insufficient (49.5 ± 36.2 pg/mL) and sufficient groups (28.7 ± 14.9 pg/mL) (P < 0.001). IL-10 levels did not vary significantly across vitamin D status groups. Pearson's correlation demonstrated a significant inverse relationship between vitamin D(3) and IL-6 (r = -0.444; P < 0.001), while correlations with IL-10, VAS, and WOMAC scores were non-significant. CONCLUSIONS: A significant inverse association between serum vitamin D(3) levels and IL-6 concentrations highlights a potential role of vitamin D in modulating inflammation in knee OA. However, no correlation was observed between vitamin D status, cytokine levels, and clinical OA severity. Longitudinal research is required to assess the therapeutic implications of vitamin D supplementation on inflammation and OA progression.