Differential Immunomodulatory Potential of Silver Nanoparticles and Effect on the Kynurenine Pathway in Male Wistar Rats

Silver nanoparticles are increasingly being used in a wide variety of ways that may lead to frequency of exposure for humans and the environment. Thus, it is necessary to understand the biological effect(s) of these nanoparticles. Previously, we showed that AgNPs activated the kynurenine pathway in rat brain independently of oxidative stress in rats. This present study is aimed at evaluating the effect of AgNPs on some selected cytokines, redox parameters, and on the kynurenine level in rats. Male Wistar rats (130-150 g) were divided into 4 groups. Rats were grouped into control, AgNPs only (50 mg/kg bw), coadministration of AgNPs (50 mg/kg bw), and dexamethasone (100 mg/kg bw) and dexamethasone only (100 mg/kg bw). Results indicated that AgNPs did not significantly elevate MDA levels in rat plasma and brain relative to the control group. AgNPs caused a significant alteration in the level of rat brain and plasma total protein concentration. Meanwhile, AgNPs led to an elevation in the level of reduced glutathione (GSH) in rat plasma but decreased plasma kynurenine level significantly. Furthermore, IFN-γ level was reduced following AgNPs administration, IL-1β decreased across the treatment groups, while NF-κB was reduced in the dexamethasone only and AgNPs + dexamethasone groups when compared with the control. AgNPs led to increased IL-4 levels, while IL-10 levels decreased across the treatment groups. Taken together, our data showed a differential immunomodulatory potential of AgNPs in rats.