This trial aimed to determine the possible therapeutic and immunomodulatory effects of vitamin D3 in patients with knee OA. In this open-label clinical trial, symptoms were assessed over 3 months in patients with primary knee OA receiving oral vitamin D3 4000 IU/day. Clinical response was evaluated at baseline and 3 months using WOMAC subscores and VAS. Serum levels of cytokines IL-1β, TNF-α, IL-13, IL-17, IL-33, IL-4, and IL-10 were determined by ELISA method. Eighty patients with knee OA were included. All 80 completed the study; the median 25(OH)D3 level was 23.1 ng/ml at baseline and increased by 12.3 ng/ml after treatment. Vitamin D3 after 3 months of supplementation induced a significant reduction in VAS pain and WOMAC subscores. Using OMERACT-OARSI criteria, 86.7% of patients treated with vitamin D3 responded to treatment. At the end of 3 months, systemic values of IL-1β (p < 0.01), IL-23 (p < 0.01), and IL-33 (p < 0.01) were significantly increased, values of TNF-α (p < 0.01), IL-13 (p < 0.01), and IL-17 (p < 0.01) were significantly decreased, while value of IL-4 was not significantly changed. No adverse events were detected. Treatment with vitamin D is associated with improvement in pain, as well as stiffness and physical function. Vitamin D supplementation increased systemic values of IL-33. Our results indicate that vitamin D3 supplementation may be used as a novel therapeutic in knee OA. Future studies are needed to investigate a potential role of IL-33 in the pathogenesis of knee OA.
Keywords: IL-33; Knee osteoarthritis; Physical function; Vitamin D3.
© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.