Role of autophagy in the regulation of respiratory inflammation caused by zinc oxide nanoparticles

Abstract

Abstract Objective: To study whether zinc oxide nano-particles (ZnO-NPs) can induce cellular autophagy in neutrophils, and whether cellular autophagy is capable of regulating the degree of inflammatory response induced by ZnO-NPs, as well as to lay a basis for research relating to the toxicity of ZnO-NPs on the respiratory system. Methods: Peripheral blood neutrophils of rats were stimulated with different concentration gradients of ZnO-NPs (including 0, 5, 10, 15, 20 mg/L). The expression levels of cellular autophagy-associated protein LC3B were examined using immunoblotting (WB) method. The expression levels of inflammatory factor IL-8 in cell supernatants were examined through enzyme-linked immunoreagent adsorption assay (ELISA). The expression levels of cellular autophagy-associated proteins LC3B and P62 and inflammatory factors (IL-6, IL-8, IL-1β) were examined through stimulation with zinc oxide nanoparticles (20 mg/L) for 24 h after neutrophils were pretreated with autophagy agonist (RAPA) and autophagy inhibitor (3-MA). Results: IL-8 and LC3B expression levels were up-regulated after the stimulation of neutrophils with ZnO-NPs, the pretreatment of cells with autophagy agonist (RAPA) up-regulated the expression of ZnO-NPs-induced IL-8, IL-6, and IL-1β, and the pretreatment of cells with autophagy inhibitor 3-MA down-regulated the expression of ZnO-NPs-induced IL-8, IL-6, and IL 1β. Conclusion: ZnO-NPs are capable of inducing neutrophil autophagy, and cellular autophagy can regulate ZnO-NPs-induced neutrophil inflammatory response.