OC.30 NK cell immunotherapy reverses lung fibrosis by eliminating senescent fibroblasts

Introduction Impaired immune clearance of senescent fibroblasts is increasingly recognized as a driver of pulmonary fibrosis. Exhausted natural killer (NK) cells have been implicated in this process, yet the underlying immune evasion mechanisms remain poorly understood. Material and Methods Single-cell RNA sequencing, spectral flow cytometry, in vitro and in vivo experiments, spatial proteomics and transcriptomics, retrospective analysis of patient records and correlation studies. Results Using single-cell RNA sequencing and spectral flow cytometry, we identify the inhibitory checkpoint receptor NKG2A as the most selectively and robustly expressed NK cell checkpoint across fibrotic lung diseases. Mechanistically, our studies reveal a distinct subset of senescent fibroblasts expressing HLA-E, the high-affinity ligand for NKG2A, as key mediator of NK cell inhibition. Spatial transcriptomics, single-cell analysis, and multiplex immunofluorescence show that HLA-E-possitive senescent fibroblasts are localized to the periphery of fibroblast foci, in direct proximity to NKG2A-positive NK cells, forming an immune-privileged niche. In contrast, CTHRC1-positive myofibroblasts at the core of fibrotic foci lack HLA-E and show minimal NK engagement. Transcriptomic profiling further maps HLA-E-positive expression to the senescent HAS1-positive fibroblast subset, which is enriched in inhibitory ligands targeting NK cells. In preclinical models of lung fibrosis, HLA-E-positive fibroblasts accumulate in regions of lung injury along with NKG2A-positive NK cells. Therapeutic blockade of NKG2A restores NK cell function, promotes clearance of senescent fibroblasts, and drives resolution of pulmonary fibrosis in vivo. Translational studies demonstrate that monalizumab, a clinical-grade NKG2A inhibitor, reactivates patient-derived NK cells and significantly enhances lysis of human senescent fibroblasts in vitro. Conclusions Together, these findings uncover a spatially restricted immune checkpoint axis that allows senescent fibroblasts to evade immune NK surveillance. Targeting the HLA-E/NKG2A axis represents a promising therapeutic strategy to restore NK cell–mediated immune clearance of senescent fibroblast and reverse pulmonary fibrosis.