The role of serum cytokine level in the evaluation of the efficacy of tocilizumab for the treatment of systemic-onset juvenile idiopathic arthritis

Abstract

Objective To evaluate the value of serum cytokine level in the efficacy of tocilizumab for the treatment of systemic-onset juvenile idiopathic arthritis. Methods 30 cases with SoJIA hospitalized in Capital Institute of Paediatrics from June 2016 to October 2018 were treated with Interleukin-6 receptor antagonist(tocilizumab) injection. Among them, 20 were males(67%) and 10 were females(33%). The age at diagnosis was between 0.84 to 13years. Whiteblood cell, C-reactive protein, erythrocyte sedimentation rate, serum interleukin(IL-6, IL-2R, IL-8, IL-10, IL-1β) and tumor necrosis factor-alpha levels were observed before treatment, after the 2nd week, after the 6th week and after the 22nd week.Mann-Whitney nonparametric test and Chi-square test were used to analyze the data of cytokines pre and after-treatment. Results All of the 30 cases had fever before medication. The fever disappeared in 28 cases after using tocilizumab. One case stopped using tocilizumab because of allergic reaction and one case stopped because of poor efficacy. Among 28 cases with normal body temperature after medication, the arthritis and rash manifestations were significantly improved. WBC, AESR and CRP were all lower than those before medication. Within these 28 cases, the serum IL-6 level was168.50(67.40-589.25) pg/mL pre-treatment, 107.50(28.03-281.50) pg/mL after the 2nd week. There was no statistical difference between them(Z=-1.754, P>0.05). The serum IL-6 level was 64.05 (19.90-130.75) pg/mL after the 6th week and 24.80 (3.45-95.40) pg/mL after the 22nd week. Compared with pre-treatment, they were all lower than pre-treatment levels(Z=-2.942,-3.334,P 0.05,>0.05,>0.05). Serum IL-8 level was 200.85(95.43-364.00)pg/ml after the 2nd week, 194.50(50.75-433.00)pg/ml after the 6th week, 161.50 (38.98-308.00)pg/ml after the 22nd week. Compared with pre-treatment [96.20(59.75-371.75) pg/ml], there were no statistical difference between after and pre-treatment(Z=-0.86,-0.131,-0.186,P>0.05,>0.05,>0.05). There was no statistical difference between after the 2nd week and pre-treatment in the IL-10 level(χ2=2.33, P>0.05). The IL-10 level after 6th week and after 22nd week were all lower than pre-treatment levels(χ2=4.08, 4.08, P 0.05,>0.05,>0.05)in IL-1β level. Conclusion After treatment with tocilizumab, the levels of serum IL-6 and IL-2R are helpful to assess the activity of SoJIA and the efficacy of therapy. Key words: Cytokine; Tocilizumab; Systemic-onset juvenile idiopathic arthritis