Changes in T‐cell subsets occur in interstitial lung disease and may contribute to pathology via complicated immune cascade

The study aimed to investigate the expression profiles of transcription factors, cytokines, and co‐stimulatory molecules in helper T (Th)‐cell subsets within bronchoalveolar lavage (BAL) samples of patients with interstitial lung diseases (ILDs). Twenty ILDs patients were included in the study, comprising those with idiopathic pulmonary fibrosis (IPF) (n:8), autoimmune‐related ILDs (auto‐ILD) (n:4), and orphan diseases (O‐ILD) (n:8), alongside five control subjects. Flow cytometry was employed to evaluate the Th to cytotoxic T cell (CTL) ratio in BAL fluid, while cytopathological examination assessed macrophages, lymphocytes, and neutrophils. Quantitative real‐time polymerase chain reaction was utilized to investigate the expressions in Th1, Th2, Th17, and regulatory T (Treg) cells. Results revealed elevated Th cell to CTL ratios across all patient groups compared to controls. Furthermore, upregulation of Th1, Th2, Th17, and T‐cell factors was observed in all patient groups compared to controls. Interestingly, upregulation of CD28 and downregulation of CTLA‐4 and PD‐1 gene expression were consistent across all ILDs groups, highlighting potential immune dysregulation. This study provides a comprehensive exploration of molecular immunological mechanisms in ILDs patients, underscoring the dominance of Th2 and Th17 responses and revealing novel findings regarding the dysregulation of CD28 , CTLA‐4 , and PD‐1 expressions in ILDs for the first time.