Role of Galectin-9, CXCL-10, APRIL, TNFRII and BAFF as Biomarkers in Idiopathic Inflammatory Myopathy: A Longitudinal Cohort Study

Objective: The study aimed to evaluate serum biomarkers (Galectin-9, TNFRII, APRIL, CXCL10, and BAFF) for their utility in identifying disease activity in idiopathic inflammatory myopathies (IIM) Methods: We enrolled adult patients who satisfied the 2017 EULAR/ACR criteria for IIM and categorised them into active (n = 16) and inactive (n = 24) subgroups. Inactive disease was defined as the absence of global and extramuscular activity, stable manual muscle testing 8 (MMT-8), and normal muscle enzymes over at least 6 months. We measured serum biomarkers by enzyme-linked immunosorbent assay (ELISA) at baseline, 3 and 6 months. We employed Spearman’s correlation, ROC curves, and multiple linear regression for evaluation. Results: We included 40 patients (mean age 38 ± 10 years; median disease duration 27.5 months). The majority had dermatomyositis (DM) (62.5%), followed by anti-synthetase syndrome (ASSD) (27.5%) and polymyositis (10%). Galectin-9, APRIL, and TNFRII levels were significantly higher in active disease ( P < .05). Galectin-9 demonstrated a modest correlation with MMT-8 changes (r = 0.534). A combination of Galectin-9, TNFRII, APRIL and creatine kinase (CK) levels showed the highest ROC AUC (0.953) to detect active disease. During the study, four patients initially categorised as ‘inactive’ patients exhibited improvement of 10% in MMT-8 over 6 months. To enhance sensitivity for detecting these clinically active diseases, we assessed Galectin-9 at lower cut-offs. Levels of 1146 pg/mL and 1109 pg/mL improved sensitivity to identify active disease to 81% and 87%, respectively, without compromising specificity. Conclusion: Serum biomarkers, Galectin-9, TNFRII, and APRIL, may help in differentiating between active and inactive disease in adult IIM. Notably, persistently elevated Galectin-9 levels, even in clinically quiescent disease, may signify ongoing activity.