Immunostaining of proinflammatory cytokines in renal cortex and medulla of rats exposed to gold nanoparticles.

Recently, gold nanoparticles (GNPs) have shown promising applications in targeted drug delivery and contrast imaging. Although in vitro cytotoxicity of GNPs has been thoroughly studied, there are limited data on in vivo toxicity of GNPs. In this study, we evaluated the effects of intraperitoneally injected 10 nm and 50 nm GNPs (5 μg/animal) on the expression of proinflammatory cytokines (IL-1β, IL-6 and TNF-α) on day 1 and day 5, post-exposure. The results of immunohistochemistry showed that both 10 nm and 50 nm GNPs induced an acute phase expression of proinflammatory cytokines in renal cortex and medulla. This proinflammatory response was comparatively more intense in renal medulla than cortex. All the three cytokines were undetectable in control cortex and medulla. In conclusion, both 10 nm and 50 nm GNPs caused an acute phase induction of proinflammatory cytokines in cortex and medulla of rat kidneys. An intense immunostaining of proinflammatory cytokines in renal medulla warrants further studies to evaluate the nephrotoxicity of GNPs to validate the safe application of GNPs for contrast imaging in renal insufficiency.