Immunopeptidome profiling in pulmonary fibrosis provides a platform for identifying therapeutic targets.

Fibrosis is a severe pathological outcome of many chronic diseases, yet the therapeutic potential of targeting the altered major histocompatibility complex (MHC) class I immunopeptidome remains largely unexplored. Here we characterized the MHC class I immunopeptidomes from both fibrotic foci of human idiopathic pulmonary fibrosis lung explants and bleomycin-treated mice, identifying a diverse repertoire of fibrosis-associated peptides. Parallel profiling of bleomycin-induced pulmonary fibrosis in mice enabled the computational prioritization of therapeutic targets. In vivo, therapeutic vaccination with three candidate peptides (MAF116-124, APBB270-78 and TNS3119-127) effectively mitigated fibrosis progression in bleomycin-treated mice. Furthermore, leveraging its evolutionary conservation, we found that MAF116-124 elicited specific human cytotoxic T lymphocytes that lysed human idiopathic pulmonary fibrosis-derived myofibroblasts and M2-like macrophages. This study indicates that immunopeptidome profiling provides a robust platform for discovering translatable antifibrotic immunotherapies.