Fibrinogen enhances the inflammatory response of alveolar macrophages to TiO₂, SiO₂ and carbon nanomaterials

Abstract

Many studies have shown that the composition of the protein corona dramatically affects the response of cells to nanomaterials (NMs). However, the role of each single protein is still largely unknown. Fibrinogen (FG), one of the most abundant plasma proteins, is believed to mediate foreign-body reactions. Since this protein is absent in cell media used in in vitro toxicological tests the possible FG-mediated effects have not yet been assessed. Here, the effect of FG on the toxicity of three different kinds of inorganic NMs (carbon, SiO₂ and TiO₂) on alveolar macrophages has been investigated. A set of integrated techniques (UV–vis spectroscopy, dynamic light scattering and sodium dodecyl sulphate-polyacrylamide gel electrophoresis) have been used to study the strength and the kinetics of interaction of FG with the NMs. The inflammatory response of alveolar macrophages (MH-S) exposed to the three NMs associated with FG has also been investigated. We found that FG significantly enhances the cytotoxicity (lactate dehydrogenase leakage) and the inflammatory response (increase in nitric oxide (NO) concentration and NO synthase activation) induced by SiO₂, carbon and TiO₂ NMs on alveolar macrophages. This effect appears related to the amount of FG interacting with the NMs. In the case of carbon NMs, the activation of fibrinolysis, likely related to the exposure of cryptic sites of FG, was also observed after 24 h. These findings underline the critical role played by FG in the toxic response to NMs.

• Clotting
• fibrinogen
• inflammation
• macrophages
• protein corona

Declaration of interest

This work is part of the PhD research activity of A.M. She has been financed by the Italian Ministry of Education, University and Research (MIUR). SEM inspections have been performed at Nanofacility Piemonte INRiM, a laboratory supported by Compagnia di San Paolo Foundation. All authors declare they have no conflict of interests.

Supplementary material available online

Supplementary Figure S1-S4.