基于内源性唾液酸的类风湿性关节炎靶向递药系统的协同治疗作用研究

Chronic inflammation infiltration and irreversible bone destruction of joints are the main obstacles to treat rheumatoid arthritis（RA）. Efficacy of drugs utilized in present clinical treatments is always affected by the side effects and drug resistance. Drug Targeting Delivery System is an effective mean to treat RA safely and efficiently. Sialic acid is a neuraminic acid derivative located on the cell surface having an effect of bone repair. Meanwhile, sialylated carbohydrate substances can specificaly bind with E-selectin on the surface of inflammatory vascular endothelial cells. Our previous study demonstrated that anti-rheumatoid drug methotrexate can be effectively encapsulated into dextran-stearic acid grafted micelles (Dex-OA), achieving sustained release property. After modification with sialic acid（SA）, the in vivo distribution to inflammatory joints can be significantly improved. Based on these achievements, this project aims to study on optimization of the drug delivery systems. By improving distribution of the drug delivery system into the injured tissue, reduced infiltration of inflammatory cells, decreased release of inflammatory factor and alleviated cartilage erosion and osteoporosis will be obtained and thus significantly improving disease activity in RA. Meanwhile, the remained sialic acid residue could play an important role in bone repair and regeneration. This synergistic therapy of drug targeting and bone regeneration effect of SA and sialic acid will provide novel idea and approach for an efficient therapy of RA.

慢性炎症浸润和关节周围骨的不可逆性破坏是造成类风湿关节炎难以治疗和康复的主要原因。现有临床治疗药物的毒副作用影响其疗效，并易产生耐药性，难以实现类风湿关节炎的有效根治。药物的靶向治疗是实现其安全高效治疗的有效手段。位于细胞表面的内源性物质唾液酸具有骨质修复功效，同时唾液酸化的糖类物质可与关节炎症部位血管内皮细胞的E选择素特异性结合。我们前期研究发现：葡聚糖-硬脂酸嫁接物胶束可有效包封抗类风湿药甲氨蝶呤，实现药物的缓释；其表面进行唾液酸修饰后，可显著提高炎症关节部位的靶向分布。本项目拟在此基础上，开展递药系统的优化研究；通过递药系统的炎症关节部位的药物高度靶向，减少炎性细胞的浸润和炎症因子的释放，缓解软骨侵蚀和骨质疏松，改善疾病活动度；药物治疗后残留的唾液酸，在炎症关节部位滞留，发挥骨修复与再生作用。通过药物靶向治疗和载体材料的协同治疗，为类风湿关节炎的高效治疗提供新思路、新手段。

类风湿关节炎（Rheumatoid Arthritis，RA）是一种以多关节滑膜炎症为主要特征的系统性自身免疫疾病,甲氨蝶呤（Methotrexate, MTX）是临床一线的抗风湿药，但其毒副作用大。新型纳米给药系统可改善药物体内分布，降低药物毒副作用，且可通过载体材料的功能化实现RA的多靶点治疗。唾液酸（Sialic Acid，SA）是一类位于细胞膜最外层的九碳糖，可与E选择素特异性结合，抑制破骨细胞成熟，促进成骨细胞分化，进而促进骨的修复和再生。本研究采用唾液酸、葡聚糖和硬脂酸为原料合成了唾液酸-葡聚糖-硬脂酸（SA-Dex-OA，SDO）嫁接物，以己二胺为桥链，在其表面修饰唾液酸，成功合成了SDO嫁接物；SDO可在水性介质中自组装形成胶束，能有效负载抗类风湿药物MTX，包封率为89.39±0.26 %。载药胶束SDM粒径为117±5.77 nm，载药胶束对药物有明显的缓释效应，药物可持续释放48 h以上；SDO可通过与活化HUVEC表面上调的E-选择素特异性结合，靶向性地被激活细胞摄取；SDO嫁接物胶束可通过唾液酸介导的促胞内碱性磷酸酶活力和胞外矿化结节形成，促进成骨细胞分化和矿化；采用胶原诱导关节炎法构建RA模型，SDO嫁接物胶束经静脉给药后，可在炎症关节部位大量蓄积；经尾静脉注射给药14天后，与DM组相比，SDM组足爪肿胀程度显著减轻，滑膜组织增生和胞内线粒体肿胀情况得到有效抑制，显著改善了细胞缺血缺氧状态；同时炎性细胞浸润程度明显减轻，炎症反应得到有效抑制；另外，SDM载药胶束还可通过唾液酸介导的骨修复调控作用，上调OPG表达，下调RANKL表达，使骨代谢向骨形成倾斜，提高骨密度，发挥骨修复与再生作用；给药14 d后，血清中SDM组生化指标与正常组接近，显示SDM载药胶束的安全性。