Janus kinase-1 and 3 in ankylosing spondylitis

Background/purpose: To investigate the Janus kinase-1 and 3 (JAK-1 and 3) expression in peripheral blood mononuclear cells (PBMCs) in ankylosing spondylitis (AS). Methods: The levels of JAK-1 and JAK-3 mRNA in PBMCs, CD3 ⁺ T cells and CD14 ⁺ monocytes were measured by RT-PCR in 52 AS patients and 31 healthy controls (HCs). The demographic features, BASDAI, BASFI, HLA-B27, ESR, CRP and serum immunoglobulin A (IgA) level were recorded and correlated with the JAK-1 & JAK-3 transcripts in patients and HCs as appropriate. Results: JAK-1 and JAK-3 expression in PB CD3 ⁺ T cells plus CD14 ⁺ monocytes was significantly higher in AS patients than in HCs (p < 0.05). There is a positive correlation between JAK-1 expression in CD3 ⁺ T cells plus CD14 ⁺ monocytes and ESR, CRP, IgA, HLA-B27, peripheral arthritis, enthesitis and uveitis (all p < 0.05), respectively. JAK-1 transcript was also increased in CD14 ⁺ monocytes from patients and correlated well with ESR and CRP as the disease deteriorated. Conversely, JAK-1 was negatively correlated to chest expansion. Area under the curve of standard receiver operating characteristic suggested that JAK-1 transcript in CD3 ⁺ T cells plus CD14 ⁺ monocytes is better to predict the higher BASDAI (>4) and BASFI (>4) than ESR or CRP in AS patients. Conclusion: In AS, JAK-1 expression in PB cells rather than ESR or CRP might be regarded as a bio-marker for monitoring disease activity and functional index in AS. These findings have also suggested that JAK-1 and JAK-3 expression may play a role in the inflammatory processes in patients with AS.