1，25二羟基维生素D3缓解急性实验性自身免疫性脑脊髓炎的机制

1, 25-dihydroxyvitamin D3 promotes the apoptosis of inflammatory cells in acute experimental autoimmune encephalomyelitis：experiment with rats

目的探讨1，25二羟基维生素D3迅速减轻实验性自身免疫性脑脊髓炎（EAE）的机制。方法建立Lewis大鼠急性EAE模型；预防组及治疗组分别于致敏日及症状出现日投给1，25二羟基维生素D3。致敏后第13天处死，观察中枢神经系统病理改变，TUNEL法检测凋亡细胞，免疫组化法检测iNOS、FasL及TGF-B1的表达，并测定外周血单个核细胞（MNC）培养上清液中亚硝酸盐的含量。结果1，25二羟基维生素D，干预的预防组及治疗组与其相应对照组比较，I临床评分及病理评分均降低（均P〈0．01），凋亡细胞数增加（均P〈0．01），半定量iNOS阳性细胞数减少，但TGF-β1、FasL阳性细胞数无明显变化。1，25二羟基维生素D3干预后，EAE大鼠外周血单个核细胞培养上清中亚硝酸盐含量有增加趋势，但与对照组的差异无统计学意义。结论1，25二羟基维生素D3通过增加炎性细胞凋亡迅速缓解EAE症状，其原因可能与改变中枢神经系统的内环境有关。

Objective To investigate the mechanism of rapid amelioration of the pathological changes in experimental allergic encephalomyelitis （EAE） by 1,25-dihydroxyvitamin D3 [ 1,25-（ OH）2D3 ]. Methods Forty Lewis rats were immunized with myelin basic protein in complete Freud~ adjuvant so as to establish ESE animal models and then randomly divided into 4 equal groups ： prevention group, fed with 1, 25-（OH）2D3 since day 0 for 10 days, prevention-control group fed with peanut oil for 10 days, treatment group fed with 1, 25-（OH） 2D3 since the appearance of EAE symptoms （generally since day 10 or 11 ）, and treatment-control group fed with peanut oil since the appearance of EAE symptoms. The clinical symptoms were scored since immunization till day 12 when the clinical symptoms reached the maximum level. The rats were sacrificed 13 days after sensitization with their brains and spinal cords taken out to undergo pathological examination, in situ TUNEL staining for detecting apeptotic cells, and semiquantitative immunohistnchemical analysis to detect the inducible NO synthase （iNOS）, FasL, and tumor growth factor （TGF）-β1, that might involve in the signal pathway of apoptosis. Peripheral blood samples were collected to isolate mononuclear cells （MNCs）. The content of nitrite in the supernatant of MNC culture was evaluated. Results The scores of clinical symptoms and the pathological changes of both the prevention and treatment groups decreased conspicuously and were significantly lower than their respective control groups （ both P 〈 0.01 ）. In contrast, the apoptosis indexes of the 2 1, 25-（OH） 2D3 administration groups were significantly higher than those of the control groups （all P 〈0.01 ）. The TUNEL positive cell rates in the brain and spinal cord of the treatment and prevention groups were all significantly higher than those of their corresponding control groups （P 〈 0. 05, P 〈 0.01 ）. The numbers of iNOS positive cells in the treatment and prevention groups were both lower than those of their corresponding control groups, which was in accord with the improvement of clinical signs and tissue lesions. The levels of nitrite in the supernatant of MNC culture of the treatment and prevention groups were higher than those of their corresponding control groups, but not significantly. Conclusion Administration of 1, 25-（ OH ） 2D3 rapidly ameliorates EAE symptoms by promoting the apoptosis of inflammatory cells. The elimination of infiltrating immune cells which reverses the pathological changes in Central nervous system is associated with a favorable microenvironment provided by 1,25-（OH） 2D3, such as decreasing of iNOS.