Abstract
Superparamagnetic iron oxide nanoparticles (IONP) have been used in clinical as contrast agents to enhance magnetic resonance imaging. Previous studies reported that intranasal exposure to IONPs caused microglial proliferation and activation in mice. It remains unclear if the function of microglia against pathogens is affected by IONP. The present study investigated the effect of IONP on the functionality of microglia activated by lipopolysaccharide (LPS). Confocal imaging revealed that IONPs were rapidly engulfed by microglia. IONP exposure enhanced the expression of lysosomal membrane protein ectodermal dysplasia-1 (ED-1) and the permeability and alkalinity in lysosomes. In contrast, IONP suppressed the expression of ionized calcium-binding adaptor molecule-1 (Iba-1), a microglial activation marker, phagocytic activity, and the production of proinflammatory cytokines, including IL-1β and IL-6. Taken together, these results demonstrated that IONP interfered with the functionality and lysosomal activity of LPS-stimulated microglia, suggesting an impaired activity against Gram-negative bacteria.
