Table 1.

Summary of the effects of the Janus kinase (JAK) inhibitors tofacitinib, baricitinib, and peficitinib on fibroblast-like synoviocytes (FLSs).

JAK Inhibitor	Targets	Impact on Fibroblast-like Synoviocytes	References
Tofacitinib	JAK1, JAK2, JAK3	Tofacitinib suppresses the activity of JAK/STAT pathway induced by oncostatin M, decreases the expression of chemokines, regulates apoptosis and myofibroblast differentiation of FLSs.	[34,44,46,48,50]
Baricitinib	JAK1, JAK2	Baricitinib inhibits inflammatory responses stimulated by OSM, together with IFNγ-induced expression of gliostatin/thymidine phosphorylase. Baricitinib negatively regulates IFN signalling I FLSs.	[53,54,55,56]
Peficitinib	Pan-JAK inhibitor	Peficitinib can suppress the formation of multi-layered structures by RA-FLSs, as well as the production of MMPs, IL-6, and VEGF from these structures. The drug inhibits the secretion of MMP-3, IL-6, and VEGF from PDGF-BB-stimulated FLSs. Moreover, it suppresses FLS proliferation and chemotactic properties.	[28,58,60,62]