MMP9 and rheumatoid arthritis: Network pharmacological topology analysis showed that caffeine, 2,4-dichloro-5-methoxy-3-methylphenol, curculigoside, orcinol glucoside, and orcin were the main active ingredients of CO, and matrix metalloproteinase 9 (MMP9), transcription factor AP-1 (JUN), prostaglandin-endoperoxide synthase 2 (PTGS2), brain-derived neurotrophic factor, and receptor-type tyrosine-protein phosphatase C were the hub targets of CO for RA treatment.