Copper oxide nanoparticles induce pulmonary inflammation via triggering cellular cuproptosis

Copper oxide nanoparticles (CuO NPs) are increasingly used in various industrial fields, and the toxicity of CuO NPs raises concerns. However, the CuO NPs-induced pulmonary inflammation and the underlying mechanism have not been fully illustrated. Cellular cuproptosis provides a new perspective to elucidate the toxicity of CuO NPs. Here, we exposed C57BL/6 mice and murine alveolar macrophage cells (MH-S) to CuO NPs, respectively. A suspension of 2 mg/mL CuO NPs was directly once administered by intratracheal instillation, and mice were sacrificed on day 7. The histopathology results showed that CuO NPs induced pulmonary inflammation in C57BL/6 mice. CuO NPs increased Cu^2 + levels by 203.0 % in mouse lung tissues. Also, CuO NPs increased the cuproptosis-related indicators of ferredoxin (FDX1), dihydrolipoamide succinyltransferase (DLST), dihydrolipoamide acetyltransferase (DLAT) and Cu transporter 1 (CTR1) in both mouse lung tissues and MH-S cells. Transcript sequencing and non-targeted metabolomics indicated that CuO NPs induced cellular cuproptosis and inflammatory responses both in vivo and in vitro. Interleukin-17a (IL-17A) was remarkably increased in the process of CuO NPs-induced cellular cuproptosis. Additionally, interference of FDX1 reduced cellular cuproptosis and decreased the release of IL-17A. In summary, CuO NPs increased the accumulation of intracellular Cu²⁺ and the expressions of cuproptosis-related proteins, induced FDX1-mediated cuproptosis, and led to pulmonary inflammation in mice. This study highlights the respiratory toxicity of CuO NPs and reveals a unique cuproptosis-driven mechanism underlying the CuO NPs-induced pulmonary inflammation.