Research On NIR/pH Smart Response Nanoparticles For Photothermal-Chemotherapy Combined Therapy Of Rheumatoid Arthritis

As the final effector cells of rheumatoid arthritis?RA?,fbroblast-like synoviocytes?FLSs?are the most important factors leading to joint dysfunction.However,the therapy of RA mainly depends on the immunosuppression and inhibition of inflammation factors.While seldom therapy focuses on the hyperplasia of synovial cells and the related treatment drugs with toxic and side effects.In order to improve the efficiency of treatment,we intend to completely inhibit synoviocyte proliferation through the synergistic action of the inflammatory factor inhibitor infliximab?INF?and the chemotherapy drug methotrexate?MTX?.To further reduce the systemic toxicity of drugs,we constructed a drug carrier based on Fe₃O₄ nanoparticles,using its photothermal effect to achieve the drug's localization and release,and photothermal therapy will also produce a synergistic anti-RA effect with chemotherapy.Focusing on the“size effect”and“PEG dilemma”issues in the design of targeted nanocarriers,we first optimized the size of the optimal Fe₃O₄ nanoparticles targeting RA tissue and examined the feasibility of RA photothermal therapy?PTT?.On this basis,INF and MTX were loaded to construct the MTX-Fe₃O₄-S-PEG-INF nanocarrier.MTX-Fe₃O₄-S-PEG-INF can respond to NIR laser to achieve intelligent extracellular HS-PEG-INF shedding,which facilitates the cellular uptake of nanoparticles.Under the cooperation of PTT,achieving the inhibition of inflammation factors and the killing of hyperplastic cells.This project provide not only new method for the treatment of RA,but also new ideas for PTT applications.Concrete study content as follows:1.Investigating the optimal size for RA targeting,Fe₃O₄ nanoparticles with well-defined particle sizes?70,110,220,350 nm?and identical surface properties were developed as model nanoparticles.The synthesized Fe₃O₄ nanoparticles exhibited excellent biocompatibility and showed higher temperature response under irradiation of NIR light.Size-dependent internalization was observed when incubated with inflammatory cells.Compared with large ones,small nanoparticles were more readily be phagocytized,leading to higher cytotoxicity in vitro.However,the in vivo experiment in CIA mice demonstrated a quite different result that Fe₃O₄-220 nm exerted better accessibility to inflamed joint and resulted in higher temperature and better therapeutic effect under laser irradiation.2.Basing the optimal target size for RA,we demonstrated NIR/pH smart response nanoparticles?MTX-Fe₃O₄-S-PEG-INF?to realize synergistic effect.The nanocarrer combined PTT to achieve INF extracellularly inhibits TNF-?and intracellular delivery of the cytotoxic drug MTX kills proliferative FLSs.Infliximab?INF?was loaded on the Fe₃O₄ nanoparticles via a thermal-cleavable ferric-thiolate linker,which can realize release at their targets with high spatial and temporal accuracy when response to NIR laser.After resolving“PEG dilemma”,Fe₃O₄-MTX nano-nuclei are easily fused with cell membrane and internalized by FLSs through lysosomal pathway.So it could self-sacrificing by hydrolysis in an acidic environment to release a considerable amount of MTX within the FLSs.As a result,INF-MTX-PTT displayed an enhanced effect for killing FLSs.3.The in vivo anti-RA effect of MTX-Fe₃O₄-S-PEG-INF was studied.Under the guidance of in vivo biodistribution results,the effects of NIR/pH double-sensitized MTX-Fe₃O₄-S-PEG-INF nanoparticles on reversing RA disease progression were studied.As a result,the MTX-Fe₃O₄-S-PEG-INF was used in the CIA model achieved synergistically enhanced anti-RA effects with INF-MTX-PTT.The curative effect was significantly better than the monotherapy model.