Effects of apolipoprotein E deficiency on neuromyelitis model in vitro / 中华神经科杂志

ABSTRACT

Objective To investigate the effects of apolipoprotein E (ApoE) deficiency on neuromyelitis optica (NMO) model of spinal cord sections induced by NMO-IgG and complement in vitro.Methods NMO-IgG was extracted from the patients with NMO,and complementary serum from healthy people.The spinal cord sections of seven days old C57BL / 6J mice with wild type (WT) or ApoE knockout (ApoE-/-) were cultured for seven days.The spinal cords of the two genotypes were randomly divided into experimental groups (NMO-ApoE-/-group,NMO-WT group) and control groups (C-AopE-/-group,C-WT group),respectively.The experimental groups were treated with NMO-IgG and complementary serum,and the control groups only with complementary serum.Then all the sections were continued incubating for 24 h before harvested.Immunofluorescence staining and modified thick tissue film immunofluorescence were used to detect the expression of aquaporin 4 (AQP4),glial fibrillary acidic protein (GFAP),ionic calcium fibronectin (IBA1),myelin basic protein (MBP) and human neurofilament protein L (NFL) respectively.The lesion score was calculated according to the areas percentage of AQP4 and GFAP deficiency in spinal cord sections.Results Compared with the respective control groups,the expressions of AQP4,GFAP,MBP and NFL were deficient in the experimental groups (The percentages of missing area in the NMO-ApoE-/-group were 83.88％ ± 5.01％,82.44％ ± 6.11％,45.02％ ± 5.11％ and 54.65％ ± 7.66％ respectively,while the percentages of missing area in the C-ApoE-/-group were 10.44％ ± 4.07％,5.73％ ±0.82％,9.12％ ±1.41％ and 5.72％ ±0.81％,t=34.143,37.269,20.300,19.051,allP ＜0.05;The percentages of missing area in the NMO-WT group were 77.74％ ± 6.75％,75.62％ ± 5.76％,37.60％ ± 4.88％ and 46.29％ ± 4.98％,while the percentages of missing area in the C-WT group were 9.31％ ± 2.97％,5.80％ ± 0.82％,9.10％ ± 1.63％,5.80％ ± 0.81％ respectively,t =27.828,35.934,16.613,24.057,all P ＜ 0.05).While IBA1 was up-regulated and the damage scores were higher in both the NMO-ApoE-/-group and the NMO-WT group.The percentages of missing area in the NMO-ApoE-/-group and the NMO-WT group showed statistically significant difference (t =2.194,2.436,3.149,2.746,all P ＜ 0.05).The expression level of IBA1 in the NMO-WT group was higher than that in the C-WT group (19.88 ± 1.11 vs 11.18 ±0.65,t =25.270,P ＜0.05),while the expression level of IBA1 in the NMO-ApoE-/-group was higher than that in the NMO-WT group (25.81 ± 1.61 vs 19.88 ± 1.11,t =9.101,P ＜0.05).The degree of deficiency or up-regulation of above-mentioned proteins was more obvious in the NMO-ApoE-/-group than that in the NMO-WT group.Conclusions NMO-IgG extracted from NMO patients can induce NMO-like damage in isolated tissue at the presence of complement.ApoE deficiency promotes the further activation of microglia,thereby aggravates the injury of astrocyte in the model of NMO.