Vacuolization of Macrophages Induced by Large Amounts of Inorganic Nanoparticles Uptake to Enhance the Immune Response
Inorganic nanoparticles (NPs), particularly iron oxide (IO) and gold (Au) NPs, are widely used in a variety of biomedical applications such as diagnosis and cancer therapy. As an important component of host defense in our organisms, macrophages play a crucial role in responding to foreign substances, such as nanoparticles. Thus, it is utmost important to understand the nanotoxicity on the immune system by investigating the influences of such nanoparticles. In this study we found that macrophages can uptake large amounts of amphiphilic polymer (PMA) modified Au and IO NPs, which will induce macrophage cells vacuolization and enhance the macrophages polarization. This mechanism is an essential part of immune response in vivo. In addition, we have reported that smaller size nanoparticles (ca. 4 nm) show more significant effects on the macrophage polarization and caused lysosomal damage compared to bigger nanoparticles (ca. 14 nm). Moreover, the amount of NPs uptake by macrophages will decrease upon trapping the PMA with PEG, resulting in reducing the vacuolization and the immune response. We hypothesize that vacuoles are formed in large amounts during the NPs uptake by macrophages, which enhance the immune response and induce macrophages toward M1 polarization. These findings are potentially useful for disease treatment and understanding the immune response when NPs are used in vitro and in vivo.