OP0205 NANOCATALYTIC TREATMENT USING RU@TIO2 FOR RHEUMATOID ARTHRITIS VIA MACROPHAGE RE-POLARIZATION

Abstract

BackgroundRheumatoid arthritis (RA) is an autoimmune disorder that results in synovitis and joint destruction[[1]]. Macrophages, one of the various inflammatory cells, particularly infiltrate the RA synovial tissue and cause sustained inflammation that promote RA. And the balance of pro-inflammatory M1 macrophages and anti-inflammatory M2 macrophages in RA joints is affected by overexpressed reactive oxygen species (ROS) and hypoxia synovium, which provides potential targets for the RA treatment.ObjectivesWith the aim of alleviating the synovial inflammation in RA and restoring the balance of macrophage subtypes, we develop a catalytic nanoparticle named Ru@TiO2, which can produce O2 and scavenge ROS to reduce M1 macrophages, switch M1 phenotype to M2 phenotype.MethodsRu@TiO2was synthesized using the hydrothermal method. The morphology and nanoparticle size were observed using the transmission electron microscopy (TEM). The catalytic ROS-scavenging activities and O2generation ability were examined through •O2−scavenging, H2O2catalytic elimination and O2generation assays. For in vitro experiment, the cytotoxicity of Ru@TiO2conducted on RAW 264.7 cells was assessed by flow cytometry. To verify M1 to M2 macrophage phenotype transition and hypoxia alleviation, M1 and M2 markers and HIF-1α expression levels were evaluated by using qRT-PCR and Western Blot, respectively. In vivo, anti-inflammatory efficiency was observed after intra-joint injection of Ru@TiO2into collagen-induced arthritis mouse. The clinical scores and paw thickness for the inflamed joints with different treatments at various time points were recorded. Ultrasound (US) was used to assess the inflamed joints after treatment and RNA expression levels of M1 and M2 macrophage markers in synovial tissue were evaluated through qRT-PCR. The statistical significance among multiple groups was examined by using one-way ANOVA.ResultsThe Ru@TiO2were fusiform in shape with an average size of 67 nm. The evaluation of catalytic ROS scavenging activities and O2generation performance of Ru@TiO2showed that Ru@TiO2can achieve about 60% scavenging ratio to •O2−and about 80% producing ratio to O2at 30 min. Ru@TiO2also showed significantly increased H2O2eliminating activity compared to the TiO2. In vitro, low cytotoxicity of Ru@TiO2was displayed and the decrease of intracellular ROS level was most significant with Ru@TiO2. In addition, M1 macrophage markers (TNF-α and IL-1β) and HIF-1α expression levels were most prominently declined with Ru@TiO2. And the increase of M2 macrophage markers (Arg-1 and CD206) was most obvious when using Ru@TiO2. In vivo, the arthritis scores, paw thickness and thickness of articular cavity assessed by US in Ru@TiO2group were the lowest when compared with other treated groups. Moreover, RNA expression levels of M1 and M2 macrophage markers in synovial tissue showed the similar tendency as in vitro.ConclusionIn this study, the Ru@TiO2was successfully synthesized with efficient catalytic ROS scavenging activities and O2generation ability for the treatment of RA. In vitro, Ru@TiO2shows good cell biocompatibility and effective intracellular ROS scavenging ability. Moreover, Ru@TiO2alleviate the hypoxia condition in cells by producing O2. Furthermore, the significant and efficient polarization of M1 to M2 macrophages and suppression of inflammation were achieved both in vitro and in vivo through the treatment of Ru@TiO2, which indicated the therapeutic potential of Ru@TiO2for RA therapy.Reference[1]Mcinnes I B, Schett G. The pathogenesis of rheumatoid arthritis [J]. N Engl J Med, 2011, 365: 2205-2219.Figure 1.Acknowledgements:NIL.Disclosure of InterestsNone Declared.