Effect of geranylgeranylacetone on optic neuritis in experimental autoimmune encephalomyelitis

Optic neuritis is an acute inflammatory demyelinating syndrome of the central nervous system (CNS) that often occurs in multiple sclerosis (MS). Since it can cause irreversible visual loss, especially in the optic-spinal form of MS or neuromyelitis optica (NMO), the present study was conducted to assess the effects of geranylgeranylacetone (GGA) on optic neuritis in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS. Myelin oligodendrocyte glycoprotein-induced EAE mice received oral administration of GGA at 500 mg/kg or vehicle once daily for 22 days. The effects of GGA on the severity of optic neuritis were examined by morphological analysis on day 22. Visual functions were measured by the multifocal electroretinograms (mfERG). In addition, the effects of GGA on severity of myelitis were monitored both on clinical signs and morphological aspects. The visual function, as assessed by the second-kernel of mfERG, was significantly improved in GGA-treated mice compared with vehicle-treated mice. GGA treatment decreased the number of degenerating axons in the optic nerve and prevented cell loss in the retinal ganglion cell layer. However, the severity of demyelination in the spinal cord remained unaffected with the treatment of GGA. These results suggest that oral GGA administration has beneficial effect on the treatment for optic neuritis in the EAE mouse model of MS.     

Non‐invasive visual evoked potentials to assess optic nerve involvement in the dark agouti rat model of experimental autoimmune encephalomyelitis induced by myelin oligodendrocyte glycoprotein

Experimental autoimmune encephalomyelitis (EAE) is the primary disease model of multiple sclerosis (MS), one of the most diffused neurological diseases characterized by fatigue, muscle weakness, vision loss, anxiety and depression. EAE can be induced through injection of myelin peptides to susceptible mouse or rat strains. In particular, EAE elicited by the autoimmune reaction against myelin oligodendrocyte glycoprotein (MOG) presents the common features of human MS: inflammation, demyelination and axonal loss. Optic neuritis affects visual pathways in both MS and in several EAE models. Neurophysiological evaluation through visual evoked potential (VEP) recording is useful to check visual pathway dysfunctions and to test the efficacy of innovative treatments against optic neuritis. For this purpose, we investigate the extent of VEP abnormalities in the dark agouti (DA) rat immunized with MOG, which develops a relapsing–remitting disease course. Together with the detection of motor signs, we acquired VEPs during both early and late stages of EAE, taking advantage of a non‐invasive recording procedure that allows long follow‐up studies. The validation of VEP outcomes was determined by comparison with ON histopathology, aimed at revealing inflammation, demyelination and nerve fiber loss. Our results indicate that the first VEP latency delay in MOG‐EAE DA rats appeared before motor deficits and were mainly related to an inflammatory state. Subsequent VEP delays, detected during relapsing EAE phases, were associated with a combination of inflammation, demyelination and axonal loss. Moreover, DA rats with atypical EAE clinical course tested at extremely late time points, manifested abnormal VEPs although motor signs were mild. Overall, our data demonstrated that non‐invasive VEPs are a powerful tool to detect visual involvement at different stages of EAE, prompting their validation as biomarkers to test novel treatments against MS optic neuritis.     

Comparison of MRI signatures in pattern I and II multiple sclerosis models

The majority of individuals with multiple sclerosis (MS) exhibit T‐cell‐ and macrophage‐dominated lesions (patterns I and II; as opposed to III and IV). These lesions, in turn, may be distinguished on the basis of whether or not there are immunoglobulin and complement depositions at the sites of active myelin destruction; such depositions are found exclusively in pattern II lesions. The main aim of this study was to determine whether pattern I and pattern II MS lesions exhibit distinct MRI signatures. We have used a recently described focal MOG‐induced EAE model of the rat brain, which recapitulates many of the hallmarks of pattern II MS; we compared this with our previous work in a delayed type hypersensitivity model of a pattern I type lesion in the rat brain. Demyelinating lesions with extensive inflammation were generated, in which the T2‐weighted signal was increased. Magnetisation transfer ratio (MTR) maps revealed loss and subsequent incomplete recovery of the structure of the corpus callosum, together with changes in tissue water diffusion and an associated increase in ventricle size. Notably, the MTR changes preceeded histological demyelination and may report on the processes leading to demyelination, rather than demyelination per se. Immunohistochemically, these MRI‐detectable signal changes correlated with both inflammatory cell infiltration and later loss of myelin. Breakdown of the blood–brain barrier and an increase in the regional cerebral blood volume were also evident in and around the lesion site at the early stage of the disease. Interestingly, however, the MRI signal changes in this pattern II type MS lesion were remarkably consistent with those previously observed in a pattern I lesion. These findings suggest that the observed signal changes reflect the convergent histopathology of the two models rather than the underlying mechanisms of the disease. Copyright © 2009 John Wiley & Sons, Ltd.     

Ageing and recurrent episodes of neuroinflammation promote progressive experimental autoimmune encephalomyelitis in Biozzi ABH mice

Current therapies for multiple sclerosis (MS) reduce the frequency of relapses by modulating adaptive immune responses but fail to limit the irreversible neurodegeneration driving progressive disability. Experimental autoimmune encephalomyelitis (EAE) in Biozzi ABH mice recapitulates clinical features of MS including relapsing–remitting episodes and secondary‐progressive disability. To address the contribution of recurrent inflammatory events and ageing as factors that amplify progressive neurological disease, we examined EAE in 8‐ to 12‐week‐old and 12‐month‐old ABH mice. Compared with the relapsing–remitting (RREAE) and secondary progressive (SPEAE) EAE observed in young mice, old mice developed progressive disease from onset (PEAE) associated with pronounced axonal damage and increased numbers of CD3⁺ T cells and microglia/macrophages, but not B cells. Whereas the clinical neurological features of PEAE and SPEAE were comparable, the pathology was distinct. SPEAE was associated with significantly reduced perivascular infiltrates and T‐cell numbers in the central nervous system (CNS) compared with PEAE and the acute phase of RREAE. In contrast to perivascular infiltrates that declined during progression from RREAE into SPEAE, the numbers of microglia clusters remained constant. Similar to what is observed during MS, the microglia clusters emerging during EAE were associated with axonal damage and oligodendrocytes expressing heat‐shock protein B5, but not lymphocytes. Taken together, our data reveal that the course of EAE is dependent on the age of the mice. Younger mice show a relapsing–remitting phase followed by progressive disease, whereas old mice immediately show progression. This indicates that recurrent episodes of inflammation in the CNS, as well as age, contribute to progressive neurological disease.     

Methylprednisolone induces reversible clinical and pathological remission and loss of lymphocyte reactivity to myelin oligodendrocyte glycoprotein in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an animal model of human multiple sclerosis (MS). EAE, induced by immunisation with myelin-associated autoantigens, is characterised by an inflammatory infiltrate in the central nervous system (CNS) associated with axonal degeneration, demyelination and damage. We have recently shown in an experimental mouse model of autoimmune gastritis that methylprednisolone treatment induces a reversible remission of gastritis with regeneration of the gastric mucosa. Here, we examined the effect of oral methylprednisolone on the mouse EAE model of human MS induced by immunisation with myelin oligodendrocyte glycoprotein peptide (MOG_35–55). We examined the clinical scores, CNS pathology and lymphocyte reactivity to MOG_35–55 following treatment and withdrawal of the steroid. Methylprednisolone remitted the clinical signs of EAE and the inflammatory infiltrate in the CNS, accompanied by loss of lymphocyte reactivity to MOG_35–55 peptide. Methylprednisolone withdrawal initiated relapse of the clinical features, a return of the CNS inflammatory infiltrate and lymphocyte reactivity to MOG_35–55 peptide. This is the first study to show that methylprednisolone induced a reversible remission in the clinical and pathological features of EAE in mice accompanied by loss of lymphocyte reactivity to the encephalitogen. This model will be useful for studies directed at a better understanding of mechanisms associated with steroid-induced disease remission, relapse and remyelination and also as an essential adjunct to an overall curative strategy.     

Artemisinin therapeutic efficacy in the experimental model of multiple sclerosis

Context: The immune system through T-helper 1 (Th1) and Th17 cells play a critical role in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), whereas the Th2 responses inhibit myelin degeneration. Artemisinin, as an anti-malaria as its agent, has been used widely in the treatment of malaria, shifts the lymphocyte responses from Th1 to Th2.

Objective: In this study, we have investigated the therapeutic effects of artemisinin on the EAE treatment.

Materials and methods: EAE was induced in the inbred C57BL6 mice. High and low doses of prednisolone and artemisinin were injected daily with the control and test groups, respectively. The spleen and the brain of the mice were removed and used for ELISA and histological studies.

Results: The mean weight of mice was significantly (p value?p value p value?p value?Conclusions: Since, artemisinin can shift the immune responses from Th1 to Th2, therefore, it can be helpful in the treatment of MS after more investigation.     

Recombinant thrombomodulin ameliorates experimental autoimmune encephalomyelitis by suppressing high mobility group box 1 and inflammatory cytokines

Recombinant thrombomodulin (rTM) has pleiotrophic properties, including anti‐coagulation and anti‐inflammation; however, its effectiveness as a treatment for multiple sclerosis (MS) has not been evaluated fully. High mobility group box 1 (HMGB1) and proinflammatory cytokines, working as inflammatory mediators, are reportedly involved in the inflammatory pathogenesis of MS. The aim of this study was to determine whether rTM can be a potential therapeutic agent for experimental autoimmune encephalomyelitis (EAE). EAE mice received rTM treatment (1 mg or 0·1 mg/kg/day) from days 11 to 15 after immunization. The clinical variables, plasma levels of inflammatory cytokines and HMGB1 and pathological findings in EAE were evaluated. rTM administration ameliorated the clinical and pathological severity of EAE. An immunohistochemical study of the spinal cord showed weaker cytoplasmic HMGB1 staining in the rTM‐treated EAE mice than in the untreated EAE mice. Plasma levels of inflammatory cytokines and HMGB1 were suppressed by rTM treatment. In conclusion, rTM down‐regulated inflammatory mediators in the peripheral circulation and prevented HMGB1 release from nuclei in the central nervous system, suppressing EAE‐related inflammation. rTM could have a novel therapeutic potential for patients with MS.     

Leber''''s遗传性视神经病线粒体DNA突变二例的检测

目的检测两例Leber's遗传性视神经病的突变位点.方法常规酚-氯仿法提取2名LHON患者基因组DNA,PCR扩增后对mtDNA11778进行检测.结果mtDNA11778位点处存在G→A突变.     

Peptide T does not ameliorate experimental autoimmune encephalomyelitis (EAE) in Lewis rats

Peptide T has been shown to inhibit T cell activation and cytokine production and function. Moreover, it has been reported to be a safe treatment in humans. We have studied the ability of peptide T to prevent or ameliorate EAE in Lewis rats. Peptide T was administered subcutaneously at different doses and phases of the disease according to several treatment protocols, but we could not observe a consistent effect of peptide T ameliorating the disease. Lymph node cell proliferation and IL-4 and interferon-gamma production were also studied. We conclude that peptide T neither prevents nor ameliorates EAE in Lewis rats.     

Pathogenic mechanisms and experimental models of multiple sclerosis

Multiple sclerosis (MS) is a devastating autoimmune disease that affects more than 1 million people worldwide and severely compromises motor and sensory function through demyelination and axonal loss. This review covers current therapies, lessons learned from failed clinical trials, genetic susceptibility, key cell types involved, animal models, gene expression, and biomarker information. The current first-line therapies for MS include the type I interferons (IFN-I) and glatiramer acetate (GA) but because of their limited effectiveness new therapeutic modalities are required. Tysabri is an anti very late antigen-4 antibody that antagonizes the migration of multiple cell types and appears more efficacious as compared to the IFNs or GA. Tysabri blocks the transmigration of T cells and monocytes, which indicates that blocking multiple cell types may increase the effectiveness of the therapy. However, this therapy may increase the risk of progressive multifocal leukoencephalopathy. The major cell types hypothesized to be pathogenic include T cells and antigen-presenting cells, including B cells. The correlation of the animal model experimental autoimmune encephalomyelitis (EAE) of MS and its predictive value to determine efficacy in the clinic appears limited. However, all current therapies do demonstrate efficacy in EAE models. There are also examples of mechanisms that have worked in EAE but have failed in the clinic, such as the TNFα antagonists and anti-p40 (a subunit of IL-12 and IL-23). The MS field would benefit if clinical biomarkers were available to monitor clinical efficacy. The etiology of MS remains elusive but additional understanding of mechanisms involved in the pathogenesis of MS may guide us to more effective treatment and management of this autoimmune disease.     

Complement activation and expression during chronic relapsing experimental autoimmune encephalomyelitis in the Biozzi ABH mouse

Chronic relapsing experimental autoimmune encephalomyelitis (crEAE) in mice recapitulates many of the clinical and histopathological features of human multiple sclerosis (MS), making it a preferred model for the disease. In both, adaptive immunity and anti‐myelin T cells responses are thought to be important, while in MS a role for innate immunity and complement has emerged. Here we sought to test whether complement is activated in crEAE and important for disease. Disease was induced in Biozzi ABH mice that were terminated at different stages of the disease to assess complement activation and local complement expression in the central nervous system. Complement activation products were abundant in all spinal cord areas examined in acute disease during relapse and in the progressive phase, but were absent in early disease remission, despite significant residual clinical disease. Local expression of C1q and C3 was increased at all stages of disease, while C9 expression was increased only in acute disease; expression of the complement regulators CD55, complement receptor 1‐related gene/protein y (Crry) and CD59a was reduced at all stages of the disease compared to naive controls. These data show that complement is activated in the central nervous system in the model and suggest that it is a suitable candidate for exploring whether anti‐complement agents might be of benefit in MS.     

Optical neuritis induced by different concentrations of myelin oligodendrocyte glycoprotein presents different profiles of the inflammatory process

Abstract

Optical neuritis (ON) is characterized by inflammation of the optic nerve, and is one of the first clinical signs of multiple sclerosis (MS). Experimental autoimmune encephalomyelitis (EAE) is the animal model used to study MS and ON. The present study evaluated the induction, development and progression of ON using an EAE model induced by 100?μg or 300?μg of MOG_35–55. An EAE model was induced in C57BL/6 mice by tail base injection of 100?μg or 300?μg of MOG_35–55 in complete Freund’s adjuvant, supplemented with Mycobacterium tuberculosis. On the day of injection and 48?h later, animals received intraperitoneally 300?ng of pertussis toxin. On days 7, 10, 14, 21 and 58 the optic nerve was dissected for histological analysis, production of CCL5 and immunohistochemical detection of CD4 and CD8. The histological changes observed in the optic nerves consisted of inflammatory cell infiltrates showing varying degrees of ON in the two groups. The onset of ON in the 300?μg of MOG_35–55 group was coincident with higher production of CCL5, on day 10 after induction. However, the 100?μg MOG_35–55 group showed more intense inflammatory infiltrate on day 14 after induction, with higher amounts of CD4 and CD8, reaching an excessive demyelination process on days 21 and 58 after induction. The results suggest that two different concentrations of MOG_35–55 lead to different forms of evolution of optic neuritis.     

银杏提取物对实验性自身免疫性脑脊髓炎小鼠的影响

目的:探讨银杏提取物(GBE)对实验性自身免疫性脑脊髓炎(EAE)小鼠炎症脱髓鞘病变的影响。方法:应用髓鞘少突胶质细胞糖蛋白33-55(MOG33-55)配以完全弗氏佐剂(CFA)免疫小鼠,诱发EAE模型。将小鼠分为CFA对照组、EAE模型组和GBE治疗组(每日腹腔注射GBE70mg/kg)。通过神经功能评分、行为学实验以及免疫荧光染色,观察GBE对EAE小鼠的影响。结果:GBE组小鼠各时间段神经功能评分均低于EAE组(P0.05),行为学检测显示发病高峰期falling latency时间较EAE组延长10s;GBE组较EAE组视神经髓鞘碱性蛋白(MBP)表达水平增高,可见MBP阳性髓鞘结构包绕轴突;海马伞矢状切片免疫荧光染色证实GBE组CD11b阳性小胶质细胞较EAE组明显减少,但是GFAP阳性星形胶质细胞数量与EAE组无明显差别。结论:GBE可能通过抑制小胶质细胞激活从而延缓EAE小鼠脱髓鞘进程,提示GBE对多发性硬化具有一定的治疗作用。     

Pathogenic and regulatory roles for B cells in experimental autoimmune encephalomyelitis

A dual role of B cells in experimental autoimmune encephalomyelitis (EAE), the animal model of the human autoimmune disease multiple sclerosis (MS), has been established. In the first role, B cells contribute to the pathogenesis of EAE through the production of anti-myelin antibodies that contribute to demyelination. On the contrary, B cells have also been shown to have protective functions in that they play an essential role in the spontaneous recovery from EAE. In this review, we summarize studies conducted in a number of species demonstrating the conditions under which B cells are pathogenic in EAE. We also discuss the phenotype and anti-inflammatory mechanisms of regulatory B cells.     

Tissue structure and inflammatory processes shape viscoelastic properties of the mouse brain

Magnetic resonance elastography (MRE) is an imaging method that reveals the mechanical properties of tissue, modelled as a combination of " viscosity" and " elasticity" . We recently showed reduced brain viscoelasticity in multiple sclerosis (MS) patients compared with healthy controls, and in the relapsing–remitting disease model experimental autoimmune encephalomyelitis (EAE). However, the mechanisms by which these intrinsic tissue properties become altered remain unclear. This study investigates whether distinct regions in the mouse brain differ in their native viscoelastic properties, and how these properties are affected during chronic EAE in C57Bl/6 mice and in mice lacking the cytokine interferon‐gamma. IFN‐γ^?/? mice exhibit a more severe EAE phenotype, with amplified inflammation in the cerebellum and brain stem. Brain scans were performed in the sagittal plane using a 7 T animal MRI scanner, and the anterior (cerebral) and posterior (cerebellar) regions analyzed separately. MRE investigations were accompanied by contrast‐enhanced MRI scans, and by histopathology and gene expression analysis ex vivo. Compared with the cerebrum, the cerebellum in healthy mice has a lower viscoelasticity, i.e. it is intrinsically " softer" . This was seen both in the wild‐type mice and the IFNγ^?/? mice. During chronic EAE, C57Bl/6 mice did not show altered brain viscoelasticity. However, as expected, the IFNγ^?/? mice showed a more severe EAE phenotype, and these mice did show altered brain elasticity during the course of disease. The magnitude of the elasticity reduction correlated with F4/80 gene expression, a marker for macrophages/microglia in inflamed central nervous system tissue. Together these results demonstrate that MRE is sensitive enough to discriminate between viscoelastic properties in distinct anatomical structures in the mouse brain, and to confirm a further relationship between cellular inflammation and mechanical alterations of the brain. This study underscores the utility of MRE to monitor pathological tissue alterations in vivo. Copyright © 2015 John Wiley & Sons, Ltd.     

地塞米松对实验性自身免疫性脑脊髓炎小鼠髓鞘保护作用的研究

目的:分析地塞米松对实验性自身免疫性脑脊髓炎(EAE)小鼠炎症反应、髓鞘脱失及髓鞘再生的影响,探讨地塞米松治疗多发性硬化的新作用。方法:应用MOG35-55免疫C57BL/6小鼠建立EAE模型。小鼠随机分为正常对照组、EAE组及地塞米松组,观察各组临床症状;采用HE染色、LFB染色、透射电镜扫描及免疫组化染色方法,检测免疫后第13、20、30 d各组小鼠脊髓组织炎症反应、髓鞘脱失及髓鞘再生情况。结果:地塞米松显著降低EAE小鼠发病率、延缓起病时间、减轻疾病严重程度。各个时间点地塞米松组脊髓组织炎性细胞浸润、髓鞘脱失及轴索变性程度较EAE组明显减轻。免疫后第20、30 d,EAE组Olig2阳性细胞数较正常对照组明显增加;免疫后各时间点,地塞米松组Olig2阳性细胞数较正常对照组均明显增加,第13、20 d较EAE组明显增加。结论:地塞米松可增加脊髓组织Olig2表达、促进髓鞘再生,这可能为地塞米松治疗EAE及多发性硬化的效应途径。     

Inconsistence between number and function of autoreactive T cells in the course of experimental autoimmune encephalomyelitis

Background: Mouse experimental autoimmune encephalomyelitis (EAE) is widely used model of multiple sclerosis (MS). The role of autoreactive CD4⁺ and CD8⁺ T cells in the development of mouse EAE has been demonstrated. However, little information is available about the relation between the frequency and reactivity of myelin antigen-reactive CD4⁺ and CD8⁺ T cells in secondary lymphoid organs and their relevance with the inflammation and pathological lesion of CNS during the course of EAE mouse model.

Methods: In this study, an EAE model with a clinical course containing acute onset, peak and chronic remission stages was established in C57BL/6J mice by myelin oligodendrocyte protein (MOG)_35–55 peptide immunization, and followed by the monitoring of clinical and pathological parameters and autoreactive T cells at different stages during the course.

Results: The dynamic changes of inflammatory infiltration, myelin loss, and astrocyte proliferation in brain and spinal cord were highly consistent with clinical severity observed in EAE course. However, the frequencies of both MOG-specific CD4⁺ and CD8⁺ T cells in secondary lymphoid organs presented different dynamic trends from the IFN-γ production by MOG-reactive T cells. Meanwhile, the IL-17 production by MOG-reactive CD4⁺ T cells was consistent with the proliferation of MOG-specific CD4⁺ T cells.

Conclusions: Both CD4⁺ and CD8⁺ T cells were most sensitive to MOG antigen stimulation for IFN-γ production during the early stage of EAE, but then rapidly lost the function despite their vigorous proliferation at the peak stage and later.     

Tracking of myelin‐reactive T cells in experimental autoimmune encephalomyelitis (EAE) animals using small particles of iron oxide and MRI

Myelin‐reactive T cells are responsible for initiating the cascade of autoreactive immune responses leading to the development of multiple sclerosis. For better insights into the disease mechanism, it is of major importance to have knowledge on the sites at which these cells are active during disease progression. Herein, we investigated the feasibility of tracking myelin‐reactive T cells, upon labelled with SPIO particles, in the central nervous system (CNS) of experimental autoimmune encephalomyelitis (EAE) animals by MRI. First, we determined the optimal labelling condition leading to a high particle uptake and minimal SPIO–Poly‐l‐lysine (PLL) aggregate formation using Prussian blue staining and inductively coupled plasma spectroscopy measurements. Results from labelling of myelin reactive T cells with low concentrations of SPIO particles (i.e. 25 µg/ml) combined with different concentrations of PLL (0–1.5 µg/ml) showed that increasing amounts of PLL led to augmented levels of free remnant SPIO‐PLL aggregates. In contrast, a low PLL concentration (i.e. 0.5 µg/ml) combined with high concentrations of SPIO (i.e. 400 µg Fe/ml) led to a high labelling efficiency with minimal amounts of aggregates. Second, the labelled myelin‐reactive T cells were transferred to control rats to induce EAE. At the occurrence of hindlimb paralysis, the SPIO labelled myelin‐reactive T cells were detected in the sacral part of the spinal cord and shown to be highly confined to this region. However, upon transfer in already primed rats, T cells were more widely distributed in the CNS and shown present in the spinal cord as well as in the brain. Our study demonstrates the feasibility of tracking SPIO labelled myelin‐reactive T cells in the spinal cord as well as the brain of EAE rats upon systemic administration. Furthermore, we provide data on the optimal labelling conditions for T cells leading to a high particle uptake and minimal aggregate formation. Copyright © 2010 John Wiley & Sons, Ltd.