Nayera Saber, Mary Atef and Doaa Abdel Aziz
Background: Previous studies demonstrated that significant association was found between IL-34 synovial tissue expression and synovitis severity in RA. Furthermore the overexpression of cathepsin K in RA synovia proves that this protease may become a new and highly specific biomarker for RA. Objective: To find out whether serum levels of IL-34 and Cathepsin-K vary in patients with longstanding RA treated with biologic therapy versus early RA patients treated with conventional DMARDS. Also to estimate any association between their baseline serum levels and disease activity, subsequent joint destruction and osteoporosis. Methods: This study included forty one RA patients, 21 as a patient group who started treatment with anti TNFα therapy. Group of controls included 20 RA patients who were treated with DMARDs. Full clinical and laboratory assessment as well as radiological by Van Der Heide Sharp score (SHS) and DEXA T scores were done. Serum IL34 and cathepsin k were assessed by ELISA before and one year after treatment. Results: After one year of therapy, patients group had significant lower serum IL-34 (s.IL-34) level, cathepsin K level CRP, DAS28, DEXA T-score, and SHS. (p<0.01) than baseline values(p<0.01), while no significant change in s.IL-34, cathepsin-K in controls. Baseline sIL34 and cathepsin K were positively correlated with DAS28 and SHS and DEXA T scores (pË‚0.05). There was a significant difference in morning stiffness, DAS28, and serum IL-34 in good responders versus poor responders according to WHO/ILAR response criteria of improvement among patients group. High baseline DAS28 is independent risk factors for radiographic change in RA while high baseline CRP is a risk factor for osteoporosis in RA patients. Conclusion: Serum IL 34 and cathepsin k were strongly linked to disease activity and duration in RA patients and were highly relevant to both localized osteoporosis and generalized osteoporosis. Also, Anti TNFα therapy effectively decrease both biomarkers regardless drug type, with amelioration of clinical, laboratory and radiological parameters of RA patients.