The Roles Of Plumbagin In The Regulation Of Dendritic Cells And Experimental Autoimmune Encephalomyelitis

Multiple sclerosis(MS) is a chronic human autoimmune disease characterized by inflammatory demyelination and subsequent axon injury in the central nervous system(CNS). There is much attention about MS because of the high incidence,long disease duration and younger age. Currently, drugs for MS are all unsatisfactory, therefore, it is important to develop new drugs to cure or relieve MS. Experimental autoimmune encephalomyelitis(EAE), an classical animal model of MS, is widely used to study the mechanisms of autoimmune inflammation. Dendritic cells(DCs) are the most potent antigen-presenting cells(APCs) and play an important role in immune response initiation. Plumbagin(PL) is an herbal compound derived from medicinal plants. A number of studies have shown that PL could regulate immunity. Thus, it is possible that PL could be a new candidate drug for diseases related to immunity. However, whether PL has effects on DCs is unknown.Research objectives: In vitro, we have studied the effect of PL on human CD14+ monocyte-derived DCs differentiation, mature, antigen uptake, T cells proliferation mediated by DCs and the mRNA expression of cytokines related to inflammation. Furthermore, our study researched the role of PL on EAE and the related cellular mechanism.Experimentcontents and methods: In vitro,we separated human CD14+ monocytes from Peripheral Blood Mononuclear Cells by using a magnetic separation column, and then added cytokines to induce the differentiation of iDCs and used LPS to stimulate DCs mature. iDCs or mDC treated with or without PL were analyzed by FACS to explore expression of surface marker. Besides, endocytosis of iDCs was determined by measuring the cellular uptake of FITC-dextran. Mixed-Lymphocyte Reaction assay T cells proliferation mediated by DCs. The mRNA expression of Th1- and Th17-polarizing cytokines in mDC was determined by Real-time quantitative PCR. In vivo, mice were immunized with Myelin Oligodendrocyte Glycoprotein(MOG) to induce EAE, and PL was intraperitoneal injection. Meanwhile, mice were observed and clinical scores were assessed daily. Paraffin sections of Lumbar spinal cords were stained with H&E, Luxol fast blue. FACS was applied to detect the effect of PL on spleen DC in EAE.Experimental results: In vitro, data of FACS suggesed that PL decreased the differentiation, mature and function of iDC and mDC, including the expression of surface marker CD80, CD83, CD86 and HLA-DR on DCs, endocytosis function of iDCs and mDCs induced allogeneic T cell proliferation. In addition, PL could restrict the mRNA expression of Th1-and Th17- polarizing cytokines in mDCs. Besides, PL could restrain DCs in vivo as well. Furthermore, in our study, we found that PL could also suppress DC2.4 cells, a mice immature dendritic cell line. In vivo, PL significantly decreased disease incidence, mena clinical score, cumulative score and maximal score of EAE.Conclusion: PL could suppress the differentiation, mature and fuction of DCs, suggested PL might have immunosuppression and anti-inflammation activities. Therefore, PL could have potential therapeutical effect on DC-related autoimmune and inflammatory diseases.