Elevated serum levels of soluble T cell immunoglobulin and mucin-containing-molecule-3 in patients with idiopathic inflammatory myopathy.

Abstract

Dear Editor, T cell immunoglobulin and mucin-containing-molecule-3 (TIM-3), an important immune-checkpoint molecule, is a transmembrane glycoprotein expressed by T lymphocytes that functions in immune response and tolerance in autoimmune diseases [1]. Soluble TIM-3 (sTIM-3) is produced by alternative splicing and cleavage, and may negatively regulate T cell-mediated immune responses [2, 3]. Myositis is a common rheumatic immune-related adverse event that can occur during treatment with immune-checkpoint inhibitors [4]. However, whether immune-checkpoint proteins, including TIM-3, exert opposite effects in autoimmune diseases and cancers remains debatable. This cross-sectional study assessed serum sTIM-3 levels in patients with idiopathic inflammatory myopathy (IIM), which is characterized by muscle fibre necrosis and infiltration of inflammatory cells, particularly activated T cells and phagocytes. Seventy adult patients with IIM and 29 healthy age- and sex-matched controls were recruited at the Department of Rheumatology and Immunology, West China Hospital, Sichuan University, from May 2021 to July 2022. All patients met the Bohan and Peter criteria and the EULAR/ACR criteria (2017), and those with immune-mediated necrotizing myopathy (IMNM) met the European Neuromuscular Centre criteria (2017). Participants <18 years of age; patients with other autoimmune diseases, tumours, HIV infection, chronic liver disease, or other muscle diseases; pregnant or lactating women; and patients who had undertaken strenuous exercise within 1 week prior to recruitment were excluded from the study. Sera samples from four patients with lipid storage myopathy (LSM) were used as the non-IIM group. Disease activity was determined using the myositis activity visual analogue score (VAS), interstitial lung disease (ILD) was confirmed by high-resolution CT, and serum sTIM-3 levels were measured by ELISA (RX105593H; Ruixinbio, Quanzhou, China). Spearman correlations between serum sTIM-3 levels, clinical indicators, and disease activity were determined. This study complied with the Declaration of Helsinki and was approved by the Ethics Committee of the hospital (No. 521, 2021).