Quercetin Lowers Inflammation in an Arthritis Model
Rheumatoid arthritis (RA) is characterized by chronic inflammation of the synovial joints. This study investigated whether or not a diet deficient in vitamin E is a possible risk factor in the development of RA and evaluated the efficacy of antioxidant supplementation. Male DBA/1J mice were maintained on either a control diet (C) or a vitamin E-depleted (-VE) diet for 4 weeks before arthritis induction. The mice in the control group were subdivided into the control group (C/C), the 0.05% alpha-tocopherol-supplemented group (C/+VE), and the 0.5% quercetin-supplemented group (C/+Q). The vitamin E-depleted group was subdivided into the -VE group (-VE/-VE), the 0.05% alpha-tocopherol-supplemented group (-VE/+VE), and the 0.5% quercetin-supplemented group (-VE/+Q) (in total, six groups, 27 mice per group). The mice were maintained on the experimental diets for 9 weeks. Study results indicate that the -VE/-VE group showed higher joint tissue tumor necrosis factor-alpha and interleukin-1beta mRNA expressions, whereas alpha-tocopherol or quercetin supplementation reduced tissue cytokine mRNA levels to values comparable to those of the C/C group. The mice fed the -VE/-VE diet exhibited higher levels of circulating macrophage chemoattractant protein 1, nitric oxide, and prostaglandin E(2) compared to those in other groups. Supplementation with alpha-tocopherol or quercetin in mice fed -VE diet decreased these markers similar to those of the mice in the C/C group. No supplementation effect was observed, however, in the mice fed with the control diet prior to RA induction. These results suggest that dietary deficiency of vitamin E increases inflammatory responses and that antioxidants successfully suppress the inflammatory responses. However, significant clinical improvement may require longer observation.
Choi EJ, Bae SC, Yu R, Youn J, Sung MK. Dietary vitamin E and quercetin modulate inflammatory responses of collagen-induced arthritis in mice. J Med Food. 2009 August Department of Food and Nutrition, Sookmyung Women's University, Seoul, Republic of Korea.