Nonlethal dose of silver nanoparticles attenuates TNF-α-induced hepatic epithelial cell death through HSP70 overexpression

Silver nanoparticles (Ag-nps) have been widely used in various biomedical products. Compared with its hazardous effects extensively being studied, rare attention has been paid to the potential protective effect of Ag-nps to human health. The present study was designed to evaluate the protective effects of Ag-nps and heat shock treatment on tumor necrosis factor-alpha (TNF-alpha)-induced cell damage in Clone 9 cells. Clone 9 cells were pretreated with nonlethal concentration of Ag-nps (1 mu g/ml) or heat shock, and then cell damages were induced by TNF-mu (1 ng/ml). Protective effects of Ag-nps administration or heat shock treatment were determined by examining the TNF-alpha-induced changes in cell viabilities. The results showed that the intensity of cytotoxicity produced by TNF-alpha was alleviated upon treatment with nonlethal concentration of Ag-nps (1 mu g/ml). Similar protective effects were also found upon heat shock treatment. These data demonstrate that Ag-nps and heat shock treatment were equally capable of inducing heat shock protein 70 (HSP70) protein expression in Clone 9 cells. The results suggest that clinically Ag-nps administration is a viable strategy to induce endogenous HSP70 expression instead of applying heat shock. In conclusion, our study for the first time provides evidence that Ag-nps may act as a viable alternative for HSP70 induction clinically.