| Summary: | QiHong Wu,1 RongRong Jin,2 Ting Feng,1 Li Liu,2 Li Yang,2 YuHong Tao,3 James M Anderson,4,5 Hua Ai,2,6 Hong Li1,3 1Key Laboratory of Obstetrics, Gynecology, Pediatric Disease, and Birth Defects, Ministry of Education, West China Second University Hospital, 2National Engineering Research Center for Biomaterials, 3Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China; 4Department of Biomedical Engineering, 5Department of Pathology, Case Western Reserve University, Cleveland, OH, US; 6Department of Radiology, West China Hospital, Sichuan University, Chengdu, China Abstract: Superparamagnetic iron oxide nanoparticles have been widely used in biomedical applications, but understanding of their interactions with the biological immune system is relatively limited. This work is focused on dextran-coated iron oxide nanoparticles and their induced autophagy in human monocytes. We found that these nanoparticles can be taken up by human monocytes, followed by localization within vesicles or free in cytoplasm. Autophagosome formation was observed with increased expression of LC3II protein, the specific marker of autophagy. The autophagy substrate p62 was degraded in a dose-dependent manner, and autophagy was blocked by autophagy (or lysosome) inhibitors alone or along with iron oxide nanoparticles, indicating that autophagosome accumulation was mainly due to autophagy induction, rather than blockade of autophagy flux. Interestingly, iron oxide nanoparticles increased the viability of human monocytes, but the mechanism was not clear. We further found that inhibition of autophagy mostly attenuated the survival of cells, with acceleration of the inflammation induced by these nanoparticles. Taken together, autophagic activation in human monocytes may play a protective role against the cytotoxicity of iron oxide nanoparticles. Keywords: autophagy, cytotoxicity, human monocytes, inflammation, iron oxide nanoparticles
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