Effect of vitamin D supplementation on circulating level of autophagosome protein LC3A, inflammation, and physical performance in knee osteoarthritis.

Aberrant autophagic activity is observed in osteoarthritic joints. Vitamin D was shown to alleviate not only osteoarthritis severity, but also autophagy process. However, the influence of vitamin D on autophagy in knee osteoarthritis (KOA) remains ambiguous. This study aimed to determine the effect of vitamin D 2 on serum levels of autophagosome protein LC3A in KOA patients and whether LC3A levels were correlated with serum 25-hydroxyvitamin D (25(OH)D) and clinical outcomes of KOA patients. A total of 165 KOA patients and 25 healthy controls were recruited. Vitamin D 2 (ergocalciferol) was administered to KOA patients at a weekly dosage of 40,000 IU. Serum LC3A, knee pain and functional scores, muscle strength, physical performance, and biochemical parameters were examined before and after 6 months of vitamin D 2 supplementation. Serum LC3A levels were significantly higher in KOA patients than healthy controls. In KOA patients, vitamin D 2 supplementation significantly decreased serum LC3A levels. Furthermore, baseline levels of serum LC3A were significantly associated with radiographic severity, pain and functional scores, total cholesterol, hs-CRP, IL6, protein carbonyl, and serum 25(OH)D. After adjusting for established confounders, independent relationships between serum LC3A and radiographic severity, pain and functional scores, total cholesterol, hs-CRP, IL6, protein carbonyl, and serum 25(OH)D were also observed. Vitamin D 2 supplementation was shown to not only decrease serum levels of LC3A, inflammatory markers, as well as oxidative stress, but also improve muscle strength and physical performance in KOA patients.