Impact of Gold Nanoparticles on the Functions of Macrophages and Dendritic Cells

Abstract Background:Gold nanoparticles (AuNPs) have demonstrated outstanding performance in various biomedical applications, but their effects on the immune system remain ill-defined. We studied the impact of AuNPs on antigen-presenting cells (APCs) because of their phagocytic capacity that allows the accumulation of exogenous materials. As models, we used primary macrophages (M) and dendritic cells (DCs) originating from the bone marrow and tested the modulation of their functions, including phagocytosis, cell activation, production of cytokines and mediators and metabolic activity.Results: The AuNPs by themselves displayed no significant effect on M and DCs functions. However, when exposed to AuNPs, M and DCs responded differently to lipopolysaccharide (LPS) or Interleukin- 4(IL-4) stimulations. We showed AuNPs altered cytokine and reactive oxygen species (ROS) productions differently in M and DCs, whereas nitric oxide (NO) production by both cells remained unaffected. The metabolic profile underpins all functions of the immune cells and their polarisation. The analysis of the metabolic activity revealed that AuNPs significantly altered mitochondrial respiration and glycolysis of M, while only little effect was seen on DCs. Furthermore, we showed that T cell responses increased when antigen was presented by AuNPs-exposed DCs, leading to stronger Th1, Th2, and Th17 responses. Conclusions: Our data provide new insights into the complexity of the effects of AuNPs on the immune system. Although AuNPs may be considered on the whole to be devoid of direct significant effect, they may induce discrete modifications on some functions that can differ among the immune cells.