Tofacitinib Inhibits STAT Phosphorylation and Matrix Metalloproteinase-3, -9 and -13 Production by C28/I2 Human Juvenile Chondrocytes

Abstract

Jessica R Thorpe,1 Rachel A Wilson,2 Sam Mesiano,2 Charles J Malemud1 1Department of Medicine, Division of Rheumatic Diseases, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA; 2Department of Reproductive Biology, Case Western Reserve University School of Medicine, University Hospitals Cleveland, Cleveland, OH, 44106, USACorrespondence: Charles J Malemud, Department of Medicine, Division of Rheumatic Diseases, Foley Medical Building, 2061 Cornell Road, Room 207, Cleveland, OH, 44106-5076, USA, Tel [phone], Fax [phone], Email [email protected]; [email protected]: This in vitro study was designed to determine the effect of the pan-Janus kinase inhibitor, Tofacitinib, on basal and interleukin-6 (IL-6)-induced signal transducers and activators of transcription (STAT) phosphorylation and matrix metalloproteinase (MMP) gene expression and MMP production by C28/I2 human chondrocytes.Methods: C28/I2 chondrocytes were grown to a confluent high-density and treated either with recombinant human IL-6 (rhIL-6; 10– 20ng/mL) or maintained in the basal state for up to 60 min. MMP gene expression was determined using RT-PCR and MMP production by semi-quantitative immunohistochemistry. The effect of IL-6 with or without Tofacitinib on activation of STAT proteins was determined from quantitative Western blots.Results: C28/I2 chondrocytes produced STAT1, STAT3 and STAT5AB which were phosphorylated (p) following treatment with rhIL-6 for 30 min. Tofacitinib (2.5nM– 100nM) decreased rhIL-6-induced activation of STAT1, STAT3, and STAT5AB as well as decreasing the expression of MMP3 and MMP13 but not MMP9, MMP1 or MMP2. In addition, Tofacitinib (50nM) reduced the number of rhIL-6-induced MMP3-, and MMP13- antibody-positive C28/I2 chondrocytes. However, Tofacitinib did decrease the number of MMP9-antibody-positive C28/I2 chondrocytes.Conclusion: Taken together, these data showed that Tofacitinib, a pan-JAK small molecule inhibitor employed for the medical therapy of rheumatoid arthritis was a potent inhibitor of rhIL-6-induced STAT phosphorylation that appeared to be coupled to the inhibition of MMP-3, -9 and -13 production by C28/I2 chondrocytes.Keywords: arthritis, cytokines, Janus kinase, signal transducers and activators of transcription

Keywords

• arthritis
• cytokines
• janus kinase
• signal transducers and activators of transcription