ARG1 and rheumatoid arthritis: Sinomenine, a dextrorotatorymorphinan analogue used clinically for treating rheumatoid arthritis in China, was shown to reduce levels of proinflammatory cytokines IL-1β, IL-6 and TNF in ICH-exposed BV-2 microglia198 and increased levels of M2-like markers IL-10 and Arg1 in primary microglia exposed to erythrocyte lysate, in vitro and in mice [142,143].