Jak3 expression and Stat3 activity in patients with rheumatoid arthritis and spondyloarthropathy

Introduction: The Jak/Stat pathway (Janus kinase/signal transducer and activator of transcription) is used by many cytokines, hormones and growth factors involved in cellular mechanisms of gene expression, cellular activation, proliferation, differentiation and apoptosis. Data suggest that Jak/Stat activity is significant in the pathogenesis of rheumatoid arthritis (RA).
Objectives: The objective was to evaluate the expression of Jak3 and the activity of Stat3 in synovial fluid cells (SFCs) and blood leucocytes (BLs) in patients with RA and spondyloarthropathy (Spa) and compare it with parameters of disease activity used in clinical practice. Moreover, the relations between Jak3 expression and Stat3 activity were evaluated.
Material and methods: Nineteen patients with RA and twenty two pa­tients with Spa (ankylosing spondylitis, psoriatic arthritis and undi­ffer­entiated spondyloarthropathy) were involved in the study. Healthy individuals (n = 23) were recruited as a control group. In all groups the expression of Jak3 and the activity of Stat3 were measured using the immunocytochemic method in BLs. In 11 RA patients and in 12 Spa patients an expression of Jak3 and an activity of Stat3 were measured in SFCs. In patients laboratory parameters describing the activity of illness were measured. The X-ray pictures of the joints were also taken.
Results: In RA and Spa group, the expression of Jak3 and the activity of Stat3 were higher comparing to healthy subjects. The expression of Jak3 and Stat3 activity were higher in SFCs than BLs. A positive correlation between SFCs Stat3 activity and CRP concentration was observed. There were no correlations between Jak3 expression and Stat3 activity.
Conclusions: The function of Jak3 and Stat3 is related to the immunologic process during the course a RA and Spa. It seems that blocking this function can be a therapeutic pathway in both groups of patients.