In particular, OSM [RA Myel_2]—OSMR [RA Fibro_2, 7, 8, 9], OSM [RA Myel_2]—LIFR [RA Fibro_2, 7, 8, 9] as well as IL-6 [RA Fibro_2, 7, 8]—IL-6R [RA Myel_2] and RANKL [Fibro_9]—RANK [RA Myel_2] interactions underlie the macrophage-synovial fibroblast circuit (Fig. 4H). Here, IL6 is linked to rheumatoid arthritis.