## 4 Discussion  
OA patients often describe pain and stiffness in the joints and are thus recommended NSAIDs, which have some anti-inflammatory and analgesic effects [17]. However, prolonged use of NSAIDs results in adverse renal, hepatic, and cardiovascular effects as well as economic burden [18]. Alternative strategies have been proposed, including taking antioxidant supplements, which may reduce oxidative stress and consequently inflammation and pain. Vitamin E has been shown to reduce free radicals by donating its hydrogen and to modulate the activity of a transcription factor that regulates the expression of antioxidant enzymes [19; 20]. In the current study, pre-treatment and post-treatment of vitamin E at 100 uM effectively reduced the level of oxygen-derived free radicals (Figure 3A). Indeed, 100 uM of vitamin E pre-treatment was shown to reverse oxidant-induced alterations in chondrocytes [21]. Our results also demonstrated that pre-treating chondrocytes with vitamin E reduces the expression of IL-1\(\beta\) and MMP-13. In contrast, post-treatment of vitamin E decreases IL-1\(\beta\) and TNF-\(\alpha\) expression (Figure 4). However, treating chondrocytes with vitamin E before and after induction results in an increase in MMP-1 and a reduction in COL2A1. Our results suggested that although treating vitamin E in OA-like cells reduces the high expression of IL-1\(\beta\) and TNF-\(\alpha\) induced by H\({}_{2}\)O\({}_{2}\), it does not promote COL2A1 expression. Therefore, vitamin E might only play a role in reducing inflammation in OA-like chondrocytes by inhibiting the activity of IL-1\(\beta\). In addition, our results showed that resveratrol reduces the level of H\({}_{2}\)O\({}_{2}\)-induced free radicals, especially at 5 uM (Figure 2B). Resveratrol at 5 uM also influenced the expression of inflammatory genes, and pre-treatment of resveratrol had different effects than post-treatment. Pre-treatment of resveratrol resulted in a complete inhibition of IL-1\(\beta\) and a reduction in MMP-13, while post-treatment led to a complete inhibition of TNF-\(\alpha\) and a decrease in IL-1\(\beta\) and MMP-1 (Figure 4). Resveratrol has been demonstrated to suppress IL-1\(\beta\)-induced proinflammatory and MMP production in cell culture models of OA [22; 23; 24]. Resveratrol also reduced cartilage tissue destruction in a rabbit model of OA [25]. Evidence shows that resveratrol is an activator of sirutin 1 (SIRT 1), which plays a  
Figure 4: The inflammatory gene expression of OA-like chondrocytes when treated with vitamin E and resveratrolrol. The expressions of IL-1\(\beta\), TNF-\(\alpha\), MMP-1, MMP-13, and COL2A1 when the chondrocytes were pre-treated with 100 uM of vitamin E (gray slashed bars), 5 uM of resveratrol (black bars), or their combination (dotted bars), or when the chondrocytes were post-treated with vitamin E (dark gray bars), resveratrol (horizontal striped bars), or their combination (light gray bars). * \(p<0.05\), ** \(p<0.01\), and *** \(p<0.001\) compared with H\({}_{2}\)O\({}_{2}\) induction; + \(p<0.05\), ** \(p<0.01\), and *** \(p<0.001\). role in anti-inflammation along with other functions during OA progression [26]. In cell culture, resveratrol-activated SIRT 1 helps protect chondrocytes from IL-1\(\beta\)-mediated oxidative stress [27]. Treating human chondrocytes with resveratrol could produce an anti-inflammatory effect by affecting the TNF-\(\alpha\)-mediated pathway [28]. Therefore, resveratrol possibly reduces H\({}_{2}\)O\({}_{2}\)-induced free radicals and the expression of IL-1\(\beta\) (pre-treatment) and TNF-\(\alpha\) (post-treatment) by activating SIRT1. The actual molecular mechanism of resveratrol in our OA-like chondrocyte model will need further investigation. Many antioxidant supplements, such as curcumin or avocado-soya extract, have been shown to be of benefit in the prevention and/or management of OA [1]. However, the effects of different combinations of antioxidant supplements on OA have rarely been investigated.