Serum IL-6 as the important biomarker in disease evaluation of polymyositis

Objective To detect the serum concentrations of interleukin-6 (IL-6) in patients with polymyositis (PM), and to explore its clinical relationships in order to investigate the pathogenesis and treatment of PM. Methods Thirty-six patients with polymyositis were enrolled from April, 2010 to January, 2014 in our study. Serum IL-6 and TNF-α were detected using a commercially available EILSA. The statistical differences between groups were evaluated by the analysis of variance (ANOVA). The Spearman's correlation test was used to evaluate the relationship of IL-6 and clinical and laboratory data. Results Serum IL-6 concentrations were (19. 67 ±7. 16) pg/ml in active PM patients, and (15. 81 ±4. 00) pg/ml in remission, which were significantly higher than those of controls[(8. 14 ±3. 71) pg/ml, P < 0. 001]. Furthermore, IL-6 concentrations in active PM patients were significantly higher than those in remission (P=0. 043). TNF-αconcentrations were (114. 44 ±36. 04) pg/ml in active PM patients, and (97. 65 ±30. 78) pg/ml in remission, which were significantly higher than those of controls[(55. 43 ±22. 83) pg/ml, P < 0. 001]. However, there was no significant deference between PM patients in active phase and in remission. The serum IL-6 levels were positively correlated TNF-α (r=0. 709, P=0. 000), and negatively correlated with current glucocorticoid dose (r=-0. 573, P=0. 000). Conclusion IL-6 could be used as a marker of hormone dosage when evaluating and treating PM disease.