Nanoplastics dysregulate macrophage function by impairing glutathione metabolism

Micro- and nanoplastics (MNPs) are emerging environmental contaminants increasingly detected in human tissues. However, how MNP-related effector mechanisms that impact the immunological function of macrophages remain elusive. Here, we demonstrated that MNPs disrupt redox homeostasis and induce immune dysfunction in bone marrow-derived macrophages. MNP internalization in macrophages impairs mitochondrial function, inducing excessive and sustained production of reactive oxygen species along with suppressed glutathione metabolism, including the substantial down-regulation of key antioxidant enzymes, such as glutathione peroxidase (GPX) 1, GPX3, and GPX4. These processes cause oxidative imbalance, thereby triggering ferroptosis, compromising cellular integrity, and amplifying inflammatory signaling. Two-photon intravital and three-dimensional imaging in mice confirmed that orally administered MNPs accumulate in multiple organs. Such MNP accumulation exacerbates lung tumor progression, potentially through chronic inflammation and the immune dysregulation of macrophages. These findings reveal a novel mechanism by which MNPs alter innate immunity and promote an inflammatory microenvironment via redox-mediated ferroptosis.