Lipoic Acid On Eae Rat Icam-1 And Tnf-¦Á And Bbb Influence

Objective:The destruction of integrated blood-brain barrier(BBB) is significant in pathogenesis of experimental autoimmune encephalomyelitis(EAE) and multiple sclerosis(MS).In present study,to provide new theoretical support of immunopathogenesis of EAE and MS we utilize lipoic acid to treat Wistar rats with EAE,observing the kinetic changes and correlation of blood brain barrier(BBB) function and intercellular adhension molecule-1(ICAM-1),tumor necrosis factor alpha(TNF-α) expression in order to observe clinical effect and potential immunologic mechanism.In addition,we hope to supply experimental evidence for clinical application of lipoic acid to treat MS and other CNS autoimmune disease.Methods:Wister rats were randomly divided into EAE group,LA group and Complete Freund Adjuvant(CFA) group.Rats of LA group were injected with LA(100mg/kg) once a day from 0 to 5 p.i..The CSF to serum albumin quotient(QA) were calculated at different time points.Clinical symptom and loss of body weight were evaluated among EAE,LA and CFA groups according to five forked method which is used international.The damage of BBB was evaluated by QA.The brain and spinal cords were removed on days from 6 to 16p.i.for immunohistochemical staining of ICAM-1 and TNF-αin different parts of CNS.The correlation between ICAM-1 and TNF-αin EAE group was analyzed.Resuits:1.On day 12p.i.,the rats of EAE group began to show apparently clinical symptoms such as,the paralysis of tail,the weakness of hind limbs,the loss of body weight and so on.On day 14p.i.the symptoms reached the peak to display hindlimb paralysis,irritability, the rapid loss of weight and even in dying state.On day 16p.i.,the symptoms began to relieve and body weight began to increase.The clinical symptom scores and incidence descended.The loss of body weight and the incidence in LA group was statistically significantly decreased when compared with those of EAE group(7.07±3.75 vs 15.06±4.20,t=5.54,p＜0.01;20% vs 73%,X~2=8.57,p＜0.01).The clinical symptom scores and the mean number of foci of infection in LA group was statistically significantly decreased when compared with those of EAE group(0.60±1.12 vs 2.07±1.67,t=3.259,p＜0.01;6.93±3.20 vs 15.20±2.11,t=8.36, p＜0.01 respectively).When compared with EAE group(13.73±1.22),the mean onset date of LA group(15.07±0.96) was statistically significantly delayed(t=3.32,p＜0.01).The disease did not appear in rats administered with Freund adjuvant and the weight of the rats increased.2.There were some common tendency in EAE group,LA group and Freund adjuvant group which QA value increased firstly and decreased then.QA value in EAE group began to increase on day 6 p.i.(0.19±0.01).On day 8p.i.,the QA value in EAE group reached the peak(0.31± 0.07),but had no clinical symptoms.This indicate the injury of BBB was prior to appearence of clinical symptom in EAE.Then the QA value decreased gradually within eight days.The QA value in LA group increased a little in the initial stage and the damage of BBB was slight.It increased generally and the peak(0.20±0.04) was later(on day 14 p.i.) than that in EAE group. The QA value of Freund adjuvant group increased in the initial stage of immunization but was lower than that in EAE group.The difference of QA was statistically significant between EAE group and LA group from 6～16 p.i.(F=16.51,P＜0.01).So was the difference of QA was statistically significant between EAE group and Freund adjuvant group from 6～16 p.i. (F=17.10,P＜0.01).3.ICAM-1 was present in vascular endothelial cell in EAE,LA and Freund adjuvant groups.The expression of ICAM-1 was at equal pace with disease severity.The staining of surrounding ancipital vascular endothelial cell was deeper when the expression of ICAM-1 increased.On day 14 p.i.,the average gray scale of ICAM-1 in EAE group reached minimum value(130.73±16.27) while it was a slower decrease with LA group(153.10±16.22).The differences of average gray scale was statistically significant between EAE group and LA group from 10～16 p.i.(P＜0.01).Our results suggest that the expression of ICAM-1 in EAE group was obviously higher than that in LA group.The differences of average gray scale was statistically significant between EAE and Freund adjuvant group from 10～16 p.i.(P＜0.01). The expression of ICAM-1 in EAE group was also obviously higher than that in Freund adjuvant group.4.Immunohistochemistry dyeing showed that surrounding lymphocyte which was effused out of blood vessel have different degree staining.The expression of TNF-αwas at equal pace with disease severity.On day 14 p.i.,the average gray scale of TNF-αin EAE group reached minimum value(114.99±19.29) while it was a slower decrease in LA group(137.57±17.63) The differences of average gray scale were statistically significant between EAE group and LA group from 10～16 p.i.(P＜0.01).The expression of TNF-αin EAE group was obviously higher than that in LA group.The differences of average gray scale was statistically significant between EAE group and Freund adjuvant group from 10～16p.i.(P＜0.01).The expression of TNF-αin EAE group was also obviously higher than that in Freund adjuvant group.There was a positive correlation of expression of ICAM-1 and TNF-αin EAE group on days 6～16 p.i.(r=0.82,P＜0.01).Conclusion:1.The injury of BBB was prior to appearence of clinical symptom in EAE.2.In different period of EAE,the expression of ICAM-1 in endothelial cells and the expression of TNF-αin CNS was in accordance to the tipically clinical symptom. 3.It was found that TNF-αexpression was statistically significant correlation with ICAM-1 expression.4.LA can inhibit EAE effectively.The underlying mechanism of LA may be related to down-regulation of ICAM-1 and TNF-α,and then protect BBB.