Environmentally Relevant Microplastic Inhalation Drives Pulmonary Fibrosis via a FABP5–FOXK2–PDGFA Macrophage Axis

Here, we identified multiple microplastic polymers in human lung tissues using pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS). Using a chronic inhalation model with environmentally relevant concentrations, we show that microplastic exposure induces progressive pulmonary fibrosis in a particle size–dependent manner, with nanoscale particles producing stronger fibrogenic effects than micron-scale particles.

Single-cell transcriptomics revealed expansion of Fabp5⁺ interstitial macrophages and early fibroblast activation specifically following nanoscale exposure. Cell–cell communication analysis identified PDGFA–PDGFRA signaling as a key mediator of macrophage–fibroblast interactions. Mechanistically, nanoscale microplastics activated a Fabp5–FOXK2–PDGFA transcriptional axis in macrophages, whereas micron-scale particles showed minimal activation.