| Objective:To explore the efficacy and therapeutic mechanism of mycophenolate mofetil(MMF) in treating rats with experimental autoimmune encephalomyelitis(EAE),which is an animal model of multiple sclerosis , by observing clinical features, pathological changes of central nervous system and detecting the ability of spleen lymphocyte proliferation,the expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and matrix metalloproteinase-9 in central nervous system.Methods:(1) The guinea pig spinal cord homogenate in complete freund's adjuvant and bordetella pertussis vaccine were both used to induce the acute EAE in Wistar rats. (2) The experimental rats were divided into normal control group, EAE model group and MMF treated group randomly.There are 12 rats in each group. Respectively, rats were given the two agents by oral gavage for a week from 10th day after immunization. The dosage of MMF was 30mg·kg-1·d-1.The rats in EAE model group were treated in stead of equal normal saline (N.S). (3) After immunization, changes of body weight and clinical scores of the experimental animals were recorded everyday. 16th day after immunization, a part of rats in each group were killed . The pathological changes of central nervous system was observed by HE staining , Luxol Fast Blue-HE staining, Bielschowsky staining and electron microscope. The ability of spleen lymphocyte proliferation was deteceted by CCK-8 method.The expression of intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and matrix metalloproteinase-9 in central nervous system were examined by immunohistochemical method. The other rats in each group were killed until 30th day after immunization to observe the whole course of disease.Results:(1)The rats immunized in our study showed typical clinical manifestation and pathological changes of acute EAE. (2)In EAE model group,maximum clinical score was(2.83±1.27), maximum loss of body weight was(34.58±13.47)g, disease duration was (16.33±1.15)d. In MMF treated group, maximum clinical score was(1.75±1.12), maximum loss of body weight was(24.67±8.42)g,disease duration was (11.67±1.53)d.The differences of maximum clinical score, maximum loss of body weight and disease duration between MMF treated group and EAE model group were statistically significant(P<0.05).Observed in HE staining ,the inflammatory infiltration of Brain ,Cerebellum and Spinal cord in EAE group were (2.50±0.55),(3.50±0.84),(3.83±0.41)respectively,which were (1.5±0.55), (2.00±0.63),(2.17±0.98)in MMF group.The statistical difference was found between two groups(P<0.05).Showed by Luxol Fast Blue-HE staining, the demyelination of Brain ,Cerebellum and Spinal cord in EAE group were (1.33±0.52), (2.00±0.63), (2.17±0.75) respectively , which were (0.83±0.41),(1.00±0.63),(1.17±0.41) in MMF group. The statistical difference was detected(P<0.05).In Bielschowsky staining, axonal damage of spinal cord were significantly improved in MMF treated group,which was (1.00±0.63) compared with EAE group ,which was (1.83±0.75)(P<0.05). Compared with EAE model group, ultrastructural changes of myelin and axon in MMF treated group were relieved. (3) Stimulation index(SI) of Spleen lymphocyte proliferation in EAE group was(2.48±0.29), which was (1.68±0.24)in MMF treated group .A statistical difference in SI was found between MMF treated group and EAE model group(P<0.05).There was statistical difference in positive blood vessel numbers of ICAM-1 and VCAM-1 between EAE model group ,which were (43.61±5.05) and (41.28±4.33) respectively and MMF treated group, which were(10.89±1.76) and (11.39±2.08) respectively(P<0.05).MMP-9 positive ratio was (46.93±6.50)% in EAE model group and (20.58±3.34)% in MMF treated group. A statistical difference was detected between two groups(P<0.05).Conclusion:(1)The method establishing acute EAE model was successful, stable and reliable in our study. (2) Mycophenolate mofetil is an effective drug in treating EAE as it can relieve the clinical signs and ameliorate pathological lesion in central nervous system of acute EAE rats. (3) The therapeutic mechanism of mycophenolate mofetil on EAE is related to suppressing immune response and may be also associated with its contribution to inhibit the expression of ICAM-1, VCAM-1 and MMP-9 in central nervous system.
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