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Received Aug 23, 2017; Accepted Jan 1, 2018
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1. Introduction
Rheumatoid arthritis (RA) is a heterogeneous systemic autoimmune disease that impairs the quality of life of patients [1] and presents with different symptoms [2]. Exterior changes involve joint malformation, swelling, and joint dysfunction [3, 4], while interior pathological changes mainly involve synovial hyperplasia and cartilage destruction. All of these changes are accompanied by systemic inflammatory responses [5, 6], involving many cytokines, such as TNF-α [7, 8] and IL-6 [9–11], which are responsible for initiating, propagating, and maintaining inflammation [12] in a complex network [13]. Recent studies have shown that TNF-α governs the crosstalk between fibroblast-like synoviocytes and chondrocytes [12] and might regulate the expressional changes in matrix-degrading enzymes and inflammatory mediators in fibroblast-like synoviocytes [12] and induce the inflammatory responses. TNF-α also governs the crosstalk between fibroblast-like synoviocytes and chondrocytes [12] and consequently induce inflammatory responses. IL-6 also plays a key role in RA. IL-6 can induce expression of vascular endothelial growth factor (VEGF) in synovial fibroblasts and other cells [14], promoting pannus formation in the synovium and causing an inflammatory response [14]. IL-6 is also implicated in damage to the articular cartilage in RA [15] and promotes further recruitment of leukocytes and inflammatory responses in the joints of RA patients [15]. Taken together, it is clear that inflammation plays an important role in the pathology of RA.
In China, traditional herbs are used as medication to treat patients with RA [16]. In traditional Chinese medicine, principles of yin-yang, the five elements, zang, and viscera guidelines are used [17]. Accordingly, prescriptions consisting of multiple herbs are used to treat RA patients, with many patients experiencing marked beneficial effects [18]. However, neither the mechanism of the complex traditional Chinese prescription, nor the active ingredients in these medications remain unknown; yet, such knowledge would be immensely valuable. Considering that one prescription is usually formulated from multiple herbs, research on such complex decoctions is complicated, and therefore it is convenient and advantageous to focus on a single herb when attempting to elucidate the mechanisms and...