Effects of Silver Nanoparticles and Silver Ion on Gap Junctional Intercellular Communication and Connexin43 Expression in Human Lung Cells

Silver nanoparticles (Ag NPs) are increasingly being used in wound dressings, medical settings, and various household products due to their unique properties and antimicrobial activity. Despite the wide-spread use of Ag NP products, the molecular mechanisms underlying the biological effects of Ag NPs remain unclear. Gap junctional intercellular communication (GJIC), formed by the connexin protein family, plays a critical role in the maintenance of tissue and organ homeostasis. This study was undertaken to investigate the effects of well characterized, PVP-coated Ag NPs (69 nm+/-3nm) and silver nitrate on GJIC and connexin43 (Cx43) expression in human lung adenocarcinoma cell line A549. Our results showed that Ag NPs increased GJIC in A549 cells as assayed by dye transfer method. Western blot analysis showed that incubation of cells with Ag NPs significantly increased the expression of Cx43 protein. Silver nitrate failed to increase GJIC and the expression of Cx43 protein. Taken together, our results provide the first evidence that Ag NPs induced the increase of GJIC activity in A549 cells through upregualtion of Cx43 protein, suggesting that Cx43 and GJIC may be one of the targets for Ag NPs biological effects.