硫酸软骨素二糖诱导的miRNAs在多发性硬化动物模型中的功能研究

Chondroitin disaccharide is the degradation product of chondroitin sulfate proteoglycan and it promotes repair in the central nervous system. Our preliminary experiments found that Chondroitin disaccharide up-regulated several specific miRNAs such as miR-29b and miR-199b, and caused dramatic inhibition of experimental autoimmune encephalomyelitis (EAE) in mice, an animal model of multiple sclerosis. Silico studies showed that both miR-29b and miR-199b may bind to 3'-untranslation region of CD44 mRNA, indicating that miR-29b and miR-199b may regulate the expression of CD44 in CD4+ splenocytes. CD44 is a cell surface transmembrane glycoprotein. It has been suggested to play a critical role in a number of biological manifestations, including cell migration, tumorigenesis, metastasis, and regulation of immune responses. Our preliminary experiments also indicated that EAE was inhibited in CD44 knockout mice, but the detail mechanism is unknown. Thus, in this study we will investigate the effects of chondroitin disaccharide and miR-29b and miR-199b on CD44 expression in mouse lymphocytes. And we also study the role of the interactions between CD44 and its ligands in the control of lymphocyte migration, and investigate the function of miR-29b and miR-199b in the blockage of EAE in mice both in vivo and in vitro. These studies are significant in that chondroitin disaccharide and miRNAs may offer preventive and therapeutic strategies for effective treatment of multiple sclerosis in the patients. These studies will also have great implications in understanding the mechanism of pathogenesis in multiple sclerosis and other autoimmune diseases.

硫酸软骨素二糖是硫酸软骨素糖蛋白的二糖降解产物，具有促进神经损伤修复的功能。我们的初步研究发现硫酸软骨素二糖可上调miR-29b和miR-199b的表达，并能抑制小鼠实验性自身免疫性脑脊髓炎的发生发展。通过计算机模拟程序我们发现miR-29b和miR-199b均可和CD44 mRNAs 3'非编码区序列结合，提示其可能对CD44的表达具有调节作用。CD44是一种细胞表面糖蛋白，在细胞迁移、肿瘤发生及转移和免疫反应过程中具有调节作用。我们前期实验也发现在CD44基因敲除小鼠上EAE的发生发展受到抑制，但具体机制不详。据此，本课题拟从整体、细胞和分子水平探讨硫酸软骨素二糖及其诱导的miRNAs对小鼠淋巴细胞CD44表达、淋巴细胞迁移以及对小鼠EAE发生发展的作用及机制。预期研究结果将揭示硫酸软骨素二糖和miRNA在多发性硬化中的作用，并为研究多发性硬化和其它自身免疫疾病的发病机理提供新的思路。

多发性硬化症是一种自身免疫性疾病，其发病机制的了解还不甚清楚，目前临床上也缺乏有效的治疗药物。利用实验性自身免疫性脑脊髓炎的小鼠模型进行研究，有助于阐明多发性硬化症的发病机理和探讨疾病治疗的新策略。通过本项目的研究，我们发现硫酸软骨素二糖能够显著增加miR-29b和miR-199b的表达，表达增强的miR-29b和miR-199b明显抑制CD44的表达，从而抑制疾病相关的CD4+T淋巴细胞的生长和迁移、抑制小鼠实验性自身免疫性脑脊髓炎的发生发展。 本项目的研究结果有助于揭示硫酸软骨素二糖、miRNA和CD44在多发性硬化中的作用，并为研究多发性硬化和其它自身免疫疾病的发病机理和有效治疗提供新的思路。