PSGL-1 is not required for development of experimental autoimmune encephalomyelitis

Adhesion molecules are essential mediators for lymphocyte trafficking through the blood-brain barrier into the CNS in multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE). However, the role of the selectin molecules and their ligand, P-selectin glycoprotein-1 (PSGL-1) which mediates tethering and rolling of the leukocytes in demyelinating disease remains controversial. This study demonstrates that mice deficient in PSGL-1 are not significantly different in the development and progression of EAE compared to wild type controls. Our observations suggest that PSGL-1-selectin interactions are redundant and not required for the development of EAE. Our data also indicate that other adhesion molecules are necessary for the initial rolling events leading to leukocyte infiltration into the CNS during EAE.     

Citrullination of central nervous system proteins during the development of experimental autoimmune encephalomyelitis

Immunization of mammals with central nervous system (CNS)-derived proteins or peptides induces experimental autoimmune encephalomyelitis (EAE), a disease resembling the human autoimmune disease multiple sclerosis (MS). Both diseases are accompanied by destruction of a part of the of the myelin sheaths, which surround neurites in the CNS. Previous studies in MS have described alterations in the citrullination of myelin basic protein, one of the main protein constituents of the myelin sheath. Here, we show that, also during the development of EAE in mice, hypercitrullination occurs in the areas of the spinal cord that show the highest degree of inflammation and that myelin basic protein and glial fibrillary acidic protein are among the hypercitrullinated proteins. We conclude that hypercitrullination of myelin proteins in the CNS is a common phenomenon in demyelinating disease. Hypercitrullination may cause conformational changes in proteins, so the affected proteins may be involved in the pathogenesis of CNS autoimmune disease by acting as autoreactive T-cell epitopes. This is the first report in which hypercitrullination of CNS proteins in EAE is described and in which proteins other than myelin basic protein are reported to be citrullinated during autoimmune-mediated CNS inflammation.     

Regulation of experimental autoimmune encephalomyelitis. Specificity of the 'recovery-associated' suppressor cells

We previously reported the presence of suppressor cells in Lewis rats at the very time of spontaneous recovery from experimental autoimmune encephalomyelitis. As these 'recovery-associated' suppressor cells might be implicated in the self-cure process, we investigated their specificity on the in vitro lymphoproliferative responses of a T cell line specific for myelin basic protein (MBP). We report now that these suppressor cells found in the thymus are specific for MBP, and not for T cell receptors, contrasting with the 'post-recovery' suppressor cell specificity reported by others. Furthermore, they do not recognize the encephalitogenic peptide 71-84, suggesting that their specificity involves an epitope outside (or partially out of) the encephalitogenic sequence.     

Regulation of experimental autoimmune encephalomyelitis: Inhibition of adoptive experimental autoimmune encephalomyelitis by ‘recovery-associated suppressor cells’

We have previously shown the presence of suppressor cells in Lewis rats at the time of spontaneous recovery from experimental autoimmune encephalomyelitis (EAE). These cells, called ‘recovery-associated suppressor cells’ (RASC), are capable of preventing active EAE and inhibiting in vitro the specific proliferative response of encephalitogenic anti-MBP T cell line cells. The present investigations were undertaken in order to lend support to the hypothesis that RASC play an active role in the recovery. We found that RASC can prevent adoptive EAE when admixed with already activated, but not resting, anti-MBP T cells or when injected into the recipients separately from the encephalitogenic cells. They can also arrest the course of an ongoing disease when injected after the beginning of the clinical signs. This study provides the first direct demonstration of the downregulation of an ongoing EAE by suppressor cells.     

Endothelial NOS‐deficient mice reveal dual roles for nitric oxide during experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a demyelinating autoimmune disease characterized by infiltration of T cells into the central nervous system (CNS) after compromise of the blood‐brain barrier. A model used to mimic the disease in mice is experimental autoimmune encephalomyelitis (EAE). In this report, we examine the clinical and histopathological course of EAE in eNOS‐deficient (eNOS^?/?) mice to determine the role of nitric oxide (NO) derived from this enzyme in the disease progression. We find that eNOS^?/? mice exhibit a delayed onset of EAE that correlates with delayed BBB breakdown, thus suggesting that NO production by eNOS underlies the T cell infiltration into the CNS. However, the eNOS^?/? mice also eventually exhibit more severe EAE and delayed recovery, indicating that NO undertakes dual roles in MS/EAE, one proinflammatory that triggers disease onset, and the other neuroprotective that promotes recovery from disease exacerbation events. © 2009 Wiley‐Liss, Inc.     

Interferon-gamma regulates oxidative stress during experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an induced inflammatory and demyelinating disease of the central nervous system which shares many clinical and pathological features with and is considered the animal model of multiple sclerosis. There is extensive evidence that EAE is a Th1 disease eliciting secretion of proinflammatory cytokines like IFN-gamma or TNF-alpha, and it has been suggested that cytokine-induced oxidative stress could have a role in EAE neuropathology. However, the individual roles of these and other cytokines in the pathogenesis of the disease are still uncertain. Here we analyze the role of IFN-gamma during EAE by using both IFN-gamma receptor-knockout (IFN-gamma R(-/-)) and wild-type mice, both strains immunized with peptide 40-55 from rat myelin oligodendrocyte glycoprotein. The levels of oxidative stress were determined through the analysis of immunoreactivity for inducible NO synthase, nitrotyrosine, and malondialdehyde, as well as through the expression of the tissue-protective antioxidant factors metallothionein I+II (MT-I+II). We also examined the number of cells undergoing apoptosis as judged by using the TUNEL technique. The levels of oxidative stress, MT-I+II, and apoptotic cell death by EAE were significantly increased in all mice, though more so in IFN-gamma R(-/-) mice compared with wild-type mice. These data support the notion that IFN-gamma has a protective role against EAE.     

Oral testosterone in male rats and the development of experimental autoimmune encephalomyelitis

OBJECTIVES: Considering that sex steroids can influence the immune system, we studied the development of experimental autoimmune encephalomyelitis (EAE), a T-cell-mediated autoimmune disease of the central nervous system, and the concomitant cell-mediated immunity in gonadally intact and gonadectomized male Wistar rats given testosterone supplementation. METHODS/RESULTS: Sham-operated rats and surgically castrated animals were orally self-administered with vehicle or testosterone added in the water bottle for 20 days before EAE induction. The androgenic effect of oral testosterone self-administration was evidenced by changes in body weight, and in the weights of androgen-dependent testes and seminal vesicles. Testosterone administration reduced the incidence of clinical signs of EAE in sham-operated animals and reversed the clinical symptoms of the disease associated with castrated EAE animals. The clinical signs observed in the different groups correlated with changes in delayed-type hypersensitivity and mononuclear cell-proliferative responses to the encephalitogenic myelin basic protein. Moreover, testosterone but not cholesterol supplementation in vitro suppressed the proliferative response of mononuclear cells to myelin basic protein suggesting that testosterone may affect specific immune functions through direct actions on immune cells. Finally, self-administration of testosterone induced also elevated corticosterone levels that in sham-operated rats correlated with the low incidence of the disease and in gonadectomized animals could be involved in the remission of clinical symptoms of EAE. CONCLUSIONS: These results suggest that orally self-administered testosterone can modulate specific cellular immune responses and serum corticosterone levels leading to changes in the development of EAE.     

PSGL-1 is dispensible for the development of active experimental autoimmune encephalomyelitis in SJL/J mice

The adhesion molecule P-selectin glycoprotein ligand (PSGL)-1 has been suggested to be involved in the immunopathogenesis of multiple sclerosis (MS). However, in C57BL/6 mice PSGL-1 was found to be dispensible for the development of MOG(aa35-55)-induced experimental autoimmune encephalomyelitis (EAE), an animal model for MS. To study, if involvement of PSGL-1 to EAE pathogenesis can be observed in another common mouse model, we backcrossed PSGL-1(-/-) mice for at least 12 generations into the SJL/J background and compared PLP(aa139-151) induced EAE in PSGL-1(-/-) SJL/J mice versus wild-type SJL/J mice. Here, we demonstrate that PSGL-1(-/-) SJL/J mice exhibited EAE pathogenesis indistinguishable from wild-type SJL/J mice. Our present study underscores and emphasizes previous observations that PSGL-1 is dispensible for EAE pathogenesis.     

Distinct roles for matrix metalloproteinase-2 and alpha4 integrin in autoimmune T cell extravasation and residency in brain parenchyma during experimental autoimmune encephalomyelitis

Expression of alpha4 integrin by auto-reactive T cells is critical for their ability to induce EAE, an autoimmune disease of the central nervous system in mice, used as a model to study human multiple sclerosis. Having previously identified one role for alpha4 integrin in adhesion-mediated induction of matrix metalloproteinase-2 (MMP-2), an enzyme that degrades the subendothelial basement membrane matrix, we investigated independent roles for MMP-2 and alpha4 integrin during EAE. The data suggest that expression of alpha4 integrin by auto-reactive T cells is important not only in mediating MMP-2 induction to facilitate entry into the CNS, but also plays a role in maintaining residency within the CNS.     

Myelin morphology and axon pathology in demyelination during experimental autoimmune encephalomyelitis

<正>In the central nervous system(CNS),oligodendrocytes are responsible for myelination by wrapping around the axon and maintaining saltatory conduction.Damage to oligodendrocytes and the myelin sheath around nerves is termed demyelination.Multiple sclerosis(MS)is an inflammatory demyelinating     

Antibodies specific for the lipid-bound form of myelin basic protein during experimental autoimmune encephalomyelitis

On the hypothesis that myelin basic protein isolated with surrounding lipids may constitute an autoantigen in demyelinating diseases we studied the antibody response to the lipid-free and lipid-bound form of myelin basic protein during the course of experimental autoimmune encephalomyelitis induced in rats with either form of protein. Immunization with the lipid-bound form of myelin basic protein induced high titres of antibodies directed to the protein, accompanied by no antibodies to cerebroside 30 days after immunization. Antibodies specifically directed to the lipid-bound form of myelin basic protein were revealed after removal of antibodies recognizing the delipidated myelin basic protein. Anti lipid-bound myelin basic protein antibodies could already be detected at day 10 post-immunization, reaching a maximum at day 20 post-immunization. Demonstrations of antibodies entirely specific for the lipid-bound form of myelin basic protein suggests that this molecule may present epitopes not to be found in its already extensively studied primary structure, possibly the result of conformational changes following lipid binding.     

Effects of prazosin on the blood-brain barrier during experimental autoimmune encephalomyelitis.

Alterations in normal function of the blood-brain barrier (BBB) are important in the pathophysiology of multiple sclerosis and its laboratory counterpart, experimental autoimmune encephalomyelitis (EAE). As part of studies on drugs that affect vascular tone in rats with EAE, we have shown previously that the specific alpha 1-adrenoreceptor antagonist, prazosin, suppressed clinical and pathologic disease. In the present study we used quantitative morphometric analysis of capillary endothelium and the tracer horseradish peroxidase (HRP) to define effects of this drug on vascular events associated with central nervous system edema. In prazosin-treated and saline-treated EAE rats, protein extravasation in the spinal cord correlated with clinical presentation. Consistent with our previous data, the results showed that increased edema was associated with increased vesicular content of capillary endothelium. In prazosin-treated rats with no clinical signs, vesicular content was comparable to that found in normal animals. With increasing severity of disease, vesicular content increased and mitochondrial content decreased. In both prazosin- and saline-treated rats, mitochondrial content was reduced even when clinical signs were slight, and sharply declined when clinical signs increased. These results suggest that damage to mitochondria may be associated with early pathological events. In prazosin-treated animals, HRP accumulated in pericytes, suggesting that these cells were a target for the action of prazosin and may restrict the extravasation of fluid into the perivascular parenchyma. Our results underscore the presence of capillary changes associated with inflammation of the central nervous system, in addition to the well-recognized cellular inflammation that is targeted to the venular bed. The extent of capillary changes was closely associated with extent of tracer leakage in the spinal cord and support the conclusion that transcytotic vesicles are involved in transport of edema fluid during EAE, and that high mitochondrial levels are important for the normal function of BBB endothelium.     

Behavioral aspects of experimental autoimmune encephalomyelitis

Acute inflammation is known to induce a depressive-like sickness behavior syndrome in humans and in experimental animals. In the present study, we sought to determine whether a chronic neuroautoimmune inflammation is also associated with a similar behavioral syndrome. Experimental autoimmune encephalomyelitis (EAE) was induced in SJL/J female mice by adoptive transfer of lymph node cells, and sickness behavior symptoms, including anorexia, loss of body weight, reduced social exploration, and decreased preference for sucrose solution were measured. We report that these components of sickness behavior were induced during the acute phase of the disease, and recovered in later phases. Moreover, the onset and recovery of the behavioral symptoms preceded the onset and recovery of the neurological signs, respectively. Since EAE is considered a model for multiple sclerosis (MS), it is suggested that EAF-induced behavioral changes may serve as a model for the depressive symptomatology that characterizes most MS patients.     

Enriched environment regulates thymocyte development and alleviates experimental autoimmune encephalomyelitis in mice

Environmental and social factors have profound impacts on immune homeostasis. Our work on environmental enrichment (EE) has revealed a novel anti-obesity and anticancer phenotype associated with enhanced activity of CD8⁺ cytotoxic T lymphocytes in secondary lymphoid tissues. Here we investigated how an EE modulated thymus and thymocyte development. EE decreased thymus mass and cellularity, decreased the double positive thymocyte population, increased the proportion of CD8⁺ T cells, reduced the CD4:CD8 ratio, and downregulated CD69 expression in T cells. In a model of multiple sclerosis: experimental autoimmune encephalomyelitis (EAE), EE alleviated symptoms, inhibited spinal cord inflammation through regulation of type 1 T-helper cells mediated by glucocorticoid receptor signaling, and prevented EAE-induced thymic disturbance. Our mechanistic studies demonstrated that hypothalamic BDNF activated a hypothalamic-pituitary-adrenal axis mediating the EE’s thymic effects. Our results indicate that a lifestyle intervention links the nervous, endocrine, and adaptive immune system, allowing the body to adapt to internal and external environments.     

Immunoregulation of experimental autoimmune encephalomyelitis by the selective CB1 receptor antagonist

During immune-mediated demyelinating lesions, the endocannabinoid system is involved in the pathogenesis of both neuroinflammation and neurodegeneration through different mechanisms. Here we explored the cellular distribution of the CB1 receptor (CB1R) in the central nervous system (CNS) and detected the level of CB1R expression during experimental autoimmune encephalomyelitis (EAE) by RT-qPCR, Western blotting, and immunostaining. Expression of CB1R was observed in neurons and microglia/macrophages but was barely detected in astrocytes. During EAE, the expression of CB1R in spinal cords was reduced at days 9, 17, and 28 postimmunization (p.i.), but the level of CB1R expression in spleens did not show a significant difference compared with complete Freund's adjuvant (CFA)-immunized mice. A selective CB1R antagonist (SR141716A) increased EAE clinical score, accompanied by weight loss. Unexpectedly, SR141716A inhibited the expression of CB1R but increased the expression of CB2R in brains, spinal cords, and spleens simultaneously. The administration of SR141716A increased interferon-γ, interleukin-17 (IL-17), and inflammatory cytokines such as IL-1β, IL-6, and tumor necrosis factor-α in brains and/or spinal cords. A similar increase was observed in spontaneous and specific antigen-stimulated splenic mononuclear cells compared with vehicle controls. Interestingly, the expression of CX3CL1 was increased in brains and spinal cords but declined in spleens of EAE mice treated with SR141716A. These results indicate that manipulation of the CB1R may have therapeutic value in MS, but its complexity remains to be carefully considered and studied in further clinical application.     

Heme oxygenase-1 in lesions of rat experimental autoimmune encephalomyelitis and neuritis

The enzyme heme oxygenase-1 (HO-1) is reducing heme to the gaseous mediator carbon monoxide, to iron and the antioxidant biliverdin. The inducible expression of HO-1 is considered a protective cellular mechanism against reactive oxygen intermediates. Further, carbon monoxide (CO) is a regulator of cGMP synthesis, of NO-synthetases and cyclooxygenases, thereby indirectly modulating reactive processes. Here we report expression of HO-1 in rat experimental autoimmune encephalomyelitis (EAE) and neuritis (EAN). With both models, similar results were obtained: HO-1 was localized predominantly to infiltrating, monocytic, but only rarely to ramified microglial cells or astrocytes surrounding the inflammatory lesions. Prominent expression by monocytic cells was seen from day 11 after immunization correlating with the development of neurologic disease. Further, local expression is persistent for long after cessation of neurologic signs. Thus, HO-1 could be considered a factor in the formation and resolution of inflammatory autoimmune lesions of the nervous system.     

Suppression of experimental autoimmune encephalomyelitis by sulfasalazine

It has recently been suggested that the sulfidopeptide leukotriene C4 (LTC4), a 5-lipoxygenase product of the arachidonic acid metabolism and one of the most potent mediators of vascular permeability, might be involved in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis (MS). Subsequently, 20 guinea pigs with EAE were treated with sulfasalazine, a substance with a proved leukotriene inhibiting effect, which has previously been described as exerting beneficial effects in patients with inflammatory bowel disease and rheumatoid arthritis. The sulfasalazine-treated guinea pigs showed a significantly better clinical outcome, as well as a significantly lower histological inflammation score compared with 19 controls.     

阿托伐他汀对实验性自身免疫性脑脊髓炎的治疗作用

目的 观察不同剂量阿托伐他汀对实验性自身免疫性脑脊髓炎(EAE)的治疗效果,探讨其作用机制.方法 采用Wistar大鼠建立EAE模型,分别应用每日每千克体重2、8 mg的阿托伐他汀进行治疗,观察其对大鼠发病率、复发率、神经功能评分和组织病理改变的影响及程度,并测定基质金属蛋白酶-9(MMP-9)和IL-4在体内的表达及含量变化.结果 EAE模型组与大剂量治疗组相比较,神经功能评分有显著改善,发病率由76.67%下降至33.33%(P=O.008),脊髓组织中血管袖套数目由3.2±1.1减少为1.3±0.4(P=0.01),血清中IL-4的含量由(0.35±0.12)ng/ml显著提高至(0.68±0.23)ng/ml(P=0.05),MMP-9在组织中的表达由37±7减少至26±5(P=0.001).结论 阿托伐他汀能改善EAE的临床表现,减轻组织损伤,其作用可能与减少MMP-9和提高IL-4含量有关.