We recently synthesized ZnO nanomaterials (denoted as ZnO nanorods [NRs] and Mini-NRs) and suggested that their cytotoxicity could be related with the activation of endoplasmic reticulum (ER) stress apoptosis. However， in a complex biological microenvironment， the ER stress-apoptosis pathway could also be modulated by biological molecules， such as free fatty acids， leading to unpredicted biological effects. In this study， we investigated the combined toxicity of ZnO NRs/Mini-NRs and palmitate (PA) to THP-1 macrophages. PA influenced the zeta potential and solubility of ZnO NRs and ZnO Mini-NRs in water， which indicated a change of colloidal stability. Exposure to ZnO NRs and Mini-NRs dose-dependent ... More
We recently synthesized ZnO nanomaterials (denoted as ZnO nanorods [NRs] and Mini-NRs) and suggested that their cytotoxicity could be related with the activation of endoplasmic reticulum (ER) stress apoptosis. However， in a complex biological microenvironment， the ER stress-apoptosis pathway could also be modulated by biological molecules， such as free fatty acids， leading to unpredicted biological effects. In this study， we investigated the combined toxicity of ZnO NRs/Mini-NRs and palmitate (PA) to THP-1 macrophages. PA influenced the zeta potential and solubility of ZnO NRs and ZnO Mini-NRs in water， which indicated a change of colloidal stability. Exposure to ZnO NRs and Mini-NRs dose-dependent decreased cellular viability and release of soluble monocyte chemotactic protein 1 (sMCP-1)， and these effects were significantly promoted with the presence of PA. However， ZnO NR- and Mini-NR-induced intracellular Zn ions or reactive oxygen species were not significantly affected by PA. ZnO NRs and ZnO Mini-NRs significantly promoted the expression of ER stress genes HSPA5， DDIT3， XBP-1s and apoptotic gene CASP3， whereas PA also modestly promoted the expression of HSPA5， DDIT3 and CASP3. Interestingly， the ER stress inducer thapsigargin showed a similar effect as PA to promote the cytotoxicity of ZnO NRs and ZnO Mini-NRs. It is suggested that PA might promote the cytotoxicity of ZnO NRs and ZnO Mini-NRs possibly by promoting ER stress.
