The anti-inflammatory effects of platinum nanoparticles on the lipopolysaccharide-induced inflammatory response in RAW 264.7 macrophages

Platinum nanoparticles (nano-Pt) have been reported to possess anti-oxidant and anti-tumor activities. However, the biological activity and mechanism of action of nano-Pt in inflammation are still unknown. The present study was designed to determine the in-vitro anti-inflammatory effects of nano-Pt on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. RAW 264.7 macrophages were used for the study. The LPS-induced production of reactive oxygen species (ROS) was determined by flow cytometry. The prostaglandin E-2 (PGE(2)) concentration was measured using a PGE(2) assay kit. The protein levels and mRNA expression of the pro-inflammatory cytokines [tumor necrosis factor-alpha, interleukin (IL)-1 beta and IL-6], along with cyclooxygenase (COX-2) and inducible nitric oxide synthase, were analyzed by Western blotting and reverse transcription-polymerase chain reaction analysis. The phosphorylation of extracellular signal regulated kinase (ERK1/2) and Akt, and the phosphorylation and degradation of inhibitory kappa B-alpha (I kappa B-alpha) was determined by Western blot analysis. Nano-Pt significantly reduced the LPS-induced production of intracellular ROS and inflammatory mediators. In addition, nano-Pt suppressed the phosphorylation of ERK1/2 and Akt, and significantly inhibited the phosphorylation/degradation of I kappa B-alpha as well as nuclear factor kappa-B (NF kappa B) transcriptional activity. These results suggest that the anti-inflammatory properties of nano-Pt may be attributed to their downregulation of the NF kappa B signaling pathway in macrophages, thus supporting the use of nano-Pt as an anti-inflammatory agent.