Alterations in oxygen metabolism are associated to lung toxicity triggered by silver nanoparticles exposure

Abstract

Along with the AgNP applications development, the concern about their possible toxicity has increasingly gained attention. As the respiratory system is one of the main exposure routes, the aim of this study was to evaluate the harmful effects developed in the lung after an acute AgNP exposure. In vivo studies using Balb/c mice intranasally instilled with 0.1 mg AgNP/kg b.w, were performed. ^99mTc-AgNP showed the lung as the main organ of deposition, where, in turn, AgNP may exert barrier injury observed by increased protein content and total cell count in BAL samples. In vivo acute exposure showed altered lung tissue O₂ consumption due to increased mitochondrial active respiration and NOX activity. Both O₂ consumption processes release ROS triggering the antioxidant system as observed by the increased SOD, catalase and GPx activities and a decreased GSH/GSSG ratio. In addition, increased protein oxidation was observed after AgNP exposure. In A549 cells, exposure to 2.5 μg/mL AgNP during 1 h resulted in augment NOX activity, decreased mitochondrial ATP associated respiration and higher H₂O₂ production rate. Lung 3D tissue model showed AgNP-initiated barrier alterations as TEER values decreased and morphological alterations. Taken together, these results show that AgNP exposure alters O₂ metabolism leading to alterations in oxygen metabolism lung toxicity. AgNP-triggered oxidative damage may be responsible for the impaired lung function observed due to alveolar epithelial injury.

Keywords: Lung epithelium; Mitochondria; NADPH oxidase; Nanoparticles; Nanotoxicology; Oxidative metabolism.