Spatially distinct molecular and immune responses to ozone exposure during mutant surfactant protein-C-induced lung injury.

Abstract

Objective: Environmental exposure and genetic mutations are key factors in the pathogenesis and exacerbation of fibrosis. This work maps the distribution ozone (O₃) signals and examines the impact of exposure in lung remodeling.

Materials and methods: Spatial transcriptomic and proteomic analyses were performed on CD68⁺ macrophages and CD45^- non-immune cells from histologically distinct regions of air- or O₃-exposed (0.8 ppm, 3 h) SP-C mutant lungs. Fibrosis was initiated by tamoxifen-mediated induction of a disease-linked Surfactant Protein (SP)-C gene mutation. The effects of O₃ exposure prior or after SP-C induction were assessed via histology, flow cytometry, and immunohistochemistry.

Results: Multi-omics analysis of O₃ injury revealed spatially restricted and cell-specific responses, characterized by mitochondrial metabolism and antioxidant pathway enrichment in injured-region macrophages, while peri-injured cells displayed pro-survival and lipid metabolism signatures. O₃ exposure induced senescence and cell-cycle regulatory signals in all CD45^- cells, with peri-injured exhibiting additional metabolic and collagen remodeling pathways. Proteomics showed widespread phospho-signaling in CD45^- cells, an effect restricted to peri-injured areas in CD68⁺ macrophages. O₃ exposure in fibrosing SP-C mutant mice caused Ly6C^hi monocyte influx at 3 days but dampened the expansion of CD4⁺/CD8⁺ T cell observed in the O₃ exposed uninduced lung. Fibrotic remodeling, cell proliferation (Ki67), and immune composition were not influenced by O₃ exposure at 7 days, though their combination increased mouse mortality and inflammatory cell activation (iNOS).

Conclusion: These data identify O₃ exposure as a modifier of regional inflammatory and stress-response pathways with modest effects on disease progression in the SP-C mutant lung.