TNF and arthritic joint disease: In rats with type II collagen-induced arthritis (CIA), matrine has been shown to decrease the degree of joint swelling, arthritis index (AI), and the joint inflammatory response by reducing the level of proinflammatory factor expression, including tumor necrosis factor-α (TNF-α), interleukin- (IL-) 1β, IL-6, IL-8, IL-17A, matrix metalloproteinase- (MMP-) 2, MMP-3, and MMP-9 [10].