Variations of the corona HDL:albumin ratio determine distinct effects of amorphous SiO2 nanoparticles on monocytes and macrophages in serum.

Aim: We investigated monocyte and macrophage death and cytokine production induced by amorphous silica nanoparticles (SiO2-NPs) to clarify the role of defined serum corona proteins. Materials & methods: The cytotoxic proinflammatory effects of SiO2-NPs on human monocytes and macrophages were characterized in no serum, in fetal calf serum and in the presence of purified corona proteins. Results: In no serum and in fetal calf serum above approximately 75 µg/ml, SiO2-NPs lysed monocytes and macrophages by plasma membrane damage (necrosis). In fetal calf serum below approximately 75 µg/ml, SiO2-NPs triggered an endolysosomal acidification and caspase-1-dependent monocyte death (pyroptosis). The corona high-density lipoproteins:albumin ratio accounted for the features of the SiO2-NPs in serum. Discussion: Corona high-density lipoproteins are a major determinant of the differential cytotoxic action of SiO2-NPs on monocytes and macrophages