Multiomic analysis identifies T cell subsets and mechanisms of epithelial interaction in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterized by progressive scarring and respiratory failure. While T cells are elevated in IPF lungs, their contributions to fibrosis beyond inflammation remain poorly understood. Here, we performed multiplex imaging and single-cell RNA and protein profiling on about 90,000 CD3+ T cells from control and fibrotic lungs, revealing 11 distinct subsets of CD4+ and CD8+ T cells, including a rare CD56+ regulatory T cell. In addition to increased T cell numbers in severely fibrotic lungs compared with non-diseased controls, we observed CD4+ and CD8+ T cells localized near epithelial cells and in niches of abnormal epithelium. CXCR4/MIF signaling emerged as a central axis mediating T cell-epithelial interactions, while epidermal growth factor receptor (EGFR) and TGF-β pathways dominated in multiple T cell subsets. Our findings support the concept that T cells in IPF adopt nonclassical activation patterns that are driven by epithelial interactions within the fibrotic microenvironment. These studies provide a foundation for exploring alternative therapeutic strategies in IPF lungs by modulating T cell behavior and communication networks.