68 Advancing a human-relevant 3D lung co-culture model for predicting effects of inhaled particles

Abstract Reliable New Approach Methodologies (NAMs) are crucial for advancing inhalation toxicology towards mechanism-based and animal-free assessment strategies. This study evaluated the predictive value of an established 3D bronchial co-culture model combining human epithelial (Calu-3) cells and monocyte-derived macrophages for assessing particle-induced inflammatory and oxidative stress responses following exposure to materials with different physicochemical properties. Using crystalline quartz (DQ12) as a reference material, exposure duration was extended to 7 d post-exposure. This revealed time-dependent increases in interleukin (IL)-1β and IL-8 on days 3 and 7, consistent with early inflammatory key events. Subsequent testing of cerium oxide (CeO₂) and barium sulfate (BaSO₄) particles demonstrated the model’s ability to distinguish active from passive particle responses: CeO₂-induced dose-dependent activation of oxidative stress and DNA repair pathways on day 3, followed by downregulation on day 7, while BaSO₄ caused only transient effects on day 3. The in vitro outcomes correlated well with known in vivo data, supporting the model’s mechanistic relevance and identifying the most relevant time points. These findings demonstrate that this in vitro co-culture model effectively captures early biological key events relevant to particle-induced inflammation and oxidative stress, reinforcing its value as a predictive NAM for inhalation toxicology.