Co-exposure effects of lead and TiO₂ nanoparticles in primary kidney cell culture from the freshwater fish Hoplias malabaricus

This study evaluated the effects of Lead (Pb) and titanium dioxide nanoparticles (TiO₂ NPs) alone or in combination in anterior kidney macrophages of the freshwater fish Hoplias malabaricus, naïve or stimulated with 1 ng.mL^-1 lipopolysaccharide (LPS). Pb (1 ×10^-5 to 1 ×10^-1 mg.mL^-1) or TiO₂ NPs (1.5 ×10^-6 to 1.5 ×10^-2 mg.mL^-1) reduced cell viability despite LPS stimulation, especially Pb 10^-1 mg.mL^-1. In combination, lower concentrations of NPs intensified Pb-induced cell viability reduction while higher concentrations restored the cell viability independently of LPS stimulation. Basal and LPS- induced NO production was reduced by both TiO2 NPs and Pb isolated. The combination of both xenobiotics avoided this reduction of NO production by the isolated compounds at lower concentrations but the protective effect was lost as the concentrations increased. None xenobiotic increase DNA fragmentation. Therefore, at specific conditions, TiO₂ NPs may have a protective effect over Pb toxicity, may also provide additional toxicity at higher concentrations.