Inhibition of anion fluxes in Calu‐3 cells by polystyrene nanoparticles: role of lipid rafts

Abstract

IntroductionThere is growing concern about the potential toxicity of non‐engineered and engineered nanoparticles. Lungs are particularly susceptible to the injury brought about by inhalation of gases and aerosols containing nanoparticles. Aims: We investigated the effects of apical exposure (up to 60 min) of cells to polystyrene nanoparticles (PNPs) (positive, negative, uncharged; 20, 50, 100nm) on transepithelial anion fluxes.MethodsCalu‐3 cells grown on inserts were mounted into modified Ussing chambers. Anion fluxes (measured as short‐circuit current, Isc) were stimulated with forskolin (10µM) in the presence or absence of PNPs (88‐104 µg/ml). In some experiments lipid rafts were disrupted by removing cell surface cholesterol with cyclodextrin (CD).ResultsForskolin resulted in mean peak increase in Isc from 29.4 to 108.4µA/cm2. All charged PNPs caused a significant (p<0.05, n.≥3) reduction of forskolin‐stimulated anion fluxes (from 24 to 40‰), an effect undetectable with uncharged particles. The CD treatment led to a significant potentiation of the inhibitory effects of 20 and 50nm PNPs. In contrast, the treatment abolished the inhibitory effects of 100nm PNPs.ConclusionOur results suggest that charge, size and interactions with lipid rafts are essential factors in determining the extent of PNPs‐mediated inhibition of forskolin‐stimulated anion fluxes in Calu‐3 cells.