MicroRNA-155 modulates Th1 and Th17 cell differentiation and is associated with multiple sclerosis and experimental autoimmune encephalomyelitis

Mammalian noncoding microRNAs (miRNAs) are suggested to be involved in immune system function. We found that miR-155 expression was highly correlated with disease severity in patients with multiple sclerosis and mice with experimental autoimmune encephalomyelitis (EAE). Knockdown of miR-155 resulted in low Th1 and Th17 cells and mild EAE, and its overexpression led to more Th1 and Th17 cells and severe EAE. MiR-155 promoted the development of inflammatory Th17/Th1 cell subsets. These findings demonstrate that miR-155 confers susceptibility to EAE by affecting inflammatory T cell responses and can be a new target for therapy of multiple sclerosis.     

Th17细胞与多发性硬化/实验性自身免疫性脑脊髓炎

多发性硬化(multiple sclerosis,MS)及其理想动物模型实验性自身免疫性脑脊髓炎(experimental autoimmune encephalomyelitis,EAE)是主要累及中枢神经系统的自身免疫性疾病.     

Therapeutic effect of ghrelin in experimental autoimmune encephalomyelitis by inhibiting antigen-specific Th1/Th17 responses and inducing regulatory T cells

Ghrelin is an important gastrointestinal hormone that regulates feeding and metabolism. Moreover, ghrelin is produced by immune cells and shows potent anti-inflammatory activities. Here, we investigated its effect in two models of experimental autoimmune encephalomyelitis (EAE) that mirror chronic and relapsing-remitting multiple sclerosis. A short systemic treatment with ghrelin after the disease onset reduced clinical severity and incidence of both forms of EAE, which was associated with a decrease in inflammatory infiltrates in spinal cord and in the subsequent demyelination. This therapeutic effect was exerted through the reduction of the autoimmune and inflammatory components of the disease. Ghrelin decreased the presence/activation of encephalitogenic Th1 and Th17 cells in periphery and nervous system, down-regulated various inflammatory mediators, and induced regulatory T cells. In summary, our findings provide a powerful rationale for the assessment of the efficacy of ghrelin as a novel therapeutic approach for treating multiple sclerosis through distinct immunomodulatory mechanisms and further support the concept that the neuroendocrine and immune systems crosstalk to finely tune the final immune response of our body.     

马索罗酚对实验性自身免疫性脑脊髓炎小鼠Th1/Th2细胞炎症因子平衡的影响

目的探讨马索罗酚对实验性自身免疫性脑脊髓炎(EAE)小鼠白细胞介素-4(IL-4)、IL-12、干扰素-γ(IFN-γ)表达的调节作用。方法将8~10周雌性C57BL/6小鼠54只随机分成对照组、模型组、治疗组。每组再随机均分为发病后10d及20d亚组,每亚组9只。采用皮下注射髓鞘少突胶质细胞糖蛋白35-55(MOG35-55)多肽0.1mL诱导EAE模型。自发病当天起,治疗组小鼠给予马索罗酚10mg/(kg·d)治疗,模型组及对照组给予等量5%二甲基亚砜(DMSO)10mL/(kg·d)处理。比较3组小鼠临床症状评分。应用实时定量PCR检测小鼠脊髓和脾组织中IL-4、IL-12、IFN-γmRNA表达水平。应用ELISA检测脑组织中IL-4、IL-12、IFN-γ蛋白表达水平。结果与模型组比较,治疗组小鼠临床症状较减轻(P0.05)。与模型组相比,治疗组小鼠10d时脊髓和脾组织IL-12、IFN-γmRNA表达水平降低(P0.05),IL-4mRNA水平增高(P0.05),脑组织IL-12、IFN-γ蛋白水平降低(P0.05),IL-4蛋白水平增高(P0.05);与模型组相比,治疗组20d时脊髓组织IL-12、IFN-γmRNA表达水平降低(P0.05),脑组织IFN-γ含量降低(P0.05)。结论马索罗酚可能通过降低脑、脊髓及脾组织中IL-12、IFN-γ表达,增加IL-4表达,调节Th1/Th2细胞炎症因子平衡,进而改善EAE小鼠疾病严重程度。     

Vav1-deficient mice are resistant to MOG-induced experimental autoimmune encephalomyelitis due to impaired antigen priming

Mice that lack the guanine nucleotide exchange factor (GEF) Vav1 exhibit particular defects in antigen-triggered T cell activation but may have an autoreactive T cell repertoire due to impaired intra-thymic negative selection. MOG(35-55)-induced experimental autoimmune encephalomyelitis (EAE) was used to test the susceptibility of Vav1(-/-) mice to organ-specific autoimmunity. Vav1(-/-) animals were found to be resistant to MOG(35-55)-EAE since the priming and in vivo expansion of myelin oligodendrocyte glycoprotein (MOG)-specific T cells was inefficient despite fully functional antigen presentation. Protection from cell-mediated autoimmunity was not due to a Th2 bias, to the lack of IL-2 or a failure of Vav1(-/-) T cells in terms of chemotactic mobility.     

Blockade of cytosolic phospholipase A2 alpha prevents experimental autoimmune encephalomyelitis and diminishes development of Th1 and Th17 responses

Cytosolic phospholipase A2 alpha (cPLA2 alpha) is the rate-limiting enzyme for release of arachidonic acid, which is converted primarily to prostaglandins via the cyclooxygenase (COX) 1/2 pathways, and leukotrienes via the 5-lipoxygenase (LO) pathway. We utilized inhibitors of cPLA2 alpha, COX-1/2 and 5-LO to determine the potential roles of these enzymes in development of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Blocking cPLA2 alpha prevented EAE development and greatly reduced antigen-induced production of Th1-type cytokines and IL-17. Blocking COX-1/2 delayed onset and reduced severity of EAE, and reduced production of Th1-type cytokines, but not IL-17. Blocking 5-LO delayed onset and reduced cumulative severity of EAE, but did not reduce production of Th1-type cytokines or IL-17. Finally, blockade of cPLA2 alpha from the onset of clinical EAE reduced duration of EAE relapses. Therefore, cPLA2 alpha represents a potential therapeutic target for treatment of MS.     

Inheritance of susceptibility to experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis is a disease of the central nervous system that can be readily induced in a variety of species by immunization with myelin proteins. It is one of the most commonly studied models of cell-mediated autoimmune disease and consequently has been important in the elucidation of many immunological functions in vivo. Nevertheless, very little is understood about the genetic and environmental factors that control the disease. Several groups have begun undertaking systematic genetic analyses in mice to identify loci that associate with increased susceptibility to disease. In this review, we will summarize the work that has been done to understand the genetic predisposition that makes certain inbred animals susceptible to disease and others resistant, and we will discuss some of the difficulties in the genetic analysis that have arisen due to the complexities of this disease model. © 1996 Wiley-Liss, Inc.     

Th17 and Th1 responses directed against the immunizing epitope, as opposed to secondary epitopes, dominate the autoimmune repertoire during relapses of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease with similarities to multiple sclerosis (MS). It has been suggested that relapses of EAE and MS may be associated with, and even driven by, T cells specific for novel epitopes that are primed during the course of tissue destruction in the target organ or in secondary lymphoid tissues. We show, however, that IFNgamma and IL-17 responses against the immunizing epitope remain dominant through out the course of multiphasic EAE. Furthermore, induction of tolerance against a putative secondary epitope did not prevent clinical relapses.     

Cerebellar susceptibility to experimental autoimmune encephalomyelitis in SJL/J mice: potential interaction of immunology with vascular anatomy

Experimental autoimmune encephalomyelitis (EAE) is utilized as an animal model for multiple sclerosis (MS). In both EAE and MS, activated T-lymphocytes specific for self-antigens present in myelin are linked to CNS inflammation and the breakdown of the blood-brain barrier (BBB) to peripheral blood leukocytes and plasma proteins, predominately in myelin rich white matter. One aspect of MS that has received relatively little attention is the finding that certain CNS regions are more likely than others to develop disease in different patient populations. Understanding the factors predisposing specific brain regions to autoimmune attack, or protecting other regions, would provide a better understanding of the disease as a process, and may also offer additional targets for therapeutic development. EAE offers a model to search for these factors and the first step in such a process is to identify the brain regions that are susceptible to EAE. Until recently the spinal cord in rodents has been considered the region most susceptible to EAE, with disease in more rostral regions occurring later and with reduced severity. However a more recent study has shown that the cerebellum of SJL/J mice, like the spinal cord, is especially susceptible to BBB breakdown in EAE. Although many factors known to be involved in BBB formation and breakdown remain to be assessed for their possible role in increasing the susceptibility of the cerebellum, one potentially important factor is the location of venules, which are the most affected vascular elements in inflamed tissue. There is a prevalence of large EAE susceptible venules traveling in the myelin rich white matter tracts in SJL/J mouse cerebellar cortex, indicating that the vascularization of this tissue may contribute to the increased susceptibility to inflammation in response to autoimmune attacks directed against CNS myelin.     

小鼠实验性自身免疫性脑脊髓炎的病理变化

目的用髓鞘少突胶质细胞糖蛋白多肽(MOG35-55)诱发实验性自身免疫性脑脊髓炎(experi-m ental autoimmune encephalomyelitis,EAE)小鼠模型。方法应用MOG35-55抗原加完全弗氏佐剂免疫C57BL/6小鼠,利用光镜、电镜观察小鼠组织学改变。结果光镜下可见小血管周围炎细胞浸润,呈袖套状改变、血管周围明显脱髓鞘及神经元变性,B ieschowsky银染显示大量轴索肿胀和轴索卵形体的形成,电镜下可见髓鞘结构松散、断裂或融合,包括不同程度的髓鞘重建,脊髓病变广泛,程度重于脑部。结论EAE的病理改变为血管周围炎性细胞浸润、白质脱髓鞘及髓鞘重建。     

Bladder dysfunction in mice with experimental autoimmune encephalomyelitis

The vast majority of patients with multiple sclerosis (MS) develop bladder control problems including urgency to urinate, urinary incontinence, frequency of urination, and retention of urine. Over 60% of MS patients show detrusor-sphincter dyssynergia, an abnormality characterized by obstruction of urinary outflow as a result of discoordinated contraction of the urethral sphincter muscle and the bladder detrusor muscle. In the current study we examined bladder function in female SWXJ mice with different defined levels of neurological impairment following induction of experimental autoimmune encephalomyelitis (EAE), an animal model of central nervous system inflammation widely used in MS research. We found that EAE mice develop profound bladder dysfunction characterized by significantly increased micturition frequencies and significantly decreased urine output per micturition. Moreover, we found that the severity of bladder abnormalities in EAE mice was directly related to the severity of clinical EAE and neurologic disability. Our study is the first to show and characterize micturition abnormalities in EAE mice thereby providing a most useful model system for understanding and treating neurogenic bladder.     

地塞米松对实验性自身免疫性脑脊髓炎小鼠IL-17表达的影响

目的研究地塞米松对实验性自身免疫性脑脊髓炎(EAE)小鼠脑及脊髓组织中IL-17表达水平及脾组织中Th17细胞比例的影响。方法将33只C57BL/6小鼠随机分为对照组、EAE组和地塞米松组。EAE组及地塞米松组小鼠以MOG35-55进行免疫造模。地塞米松组小鼠自免疫当天至处死,隔日给予地塞米松磷酸钠注射液0.07mg·kg~(-1)腹腔注射。对照组及EAE组给予等量生理盐水。观察小鼠的发病情况及神经功能评分。应用苏木精-伊红染色、免疫组织化学染色、实时定量PCR、流式细胞学方法分别检测小鼠中枢神经系统炎症细胞浸润、IL-17阳性细胞表达、IL-17m RNA水平及脾组织Th17细胞比例。结果地塞米松组与EAE组比较,小鼠发病率及神经功能评分明显降低(P0.05)。与对照组比较,EAE组小鼠脑及脊髓组织中炎性病灶数明显增多(P0.05),IL-17阳性细胞数明显增多(P0.05),脊髓组织中IL-17m RNA水平明显升高(P0.05),脾组织Th17细胞比例明显升高(P0.05);与EAE组相比较,地塞米松组小鼠脑、脊髓及脾组织中上述指标明显降低(P0.05)。结论地塞米松可以降低EAE小鼠发病率,减轻发病时神经功能损伤程度以及脑和脊髓内炎性细胞浸润程度,并使IL-17mRNA、蛋白表达水平及Th17细胞比例下降。其神经保护作用可能是通过抑制IL-17/IL-23轴等免疫调节机制而实现。     

Comparison of a classical Th1 bacteria versus a Th17 bacteria as adjuvant in the induction of experimental autoimmune encephalomyelitis

The relative contribution of myelin-specific Th1 and Th17 cells in the pathology of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), is controversial. IL-12, the key cytokine necessary for the differentiation of Th1 cells, has been found to be dispensable for EAE induction; while the related cytokine associated with Th17 cells, IL-23, is a critical factor for inducing EAE. Since EAE is induced by immunization with myelin proteins in CFA which contains M. tuberculosis that generates a prototypical Th1-mediated immune response, we sought to determine if replacing the M. tuberculosis in the adjuvant with a bacterium that induces an IL-23-dependent Th17 cell response during infection would induce EAE with a different phenotype. C. rodentium, a bacterium that requires IL-23 for protective immunity, was used as the adjuvant in EAE and compared to CFA. Mice immunized with C. rodentium adjuvant (CRA) developed classical signs of EAE, similar to CFA-immunized mice, but disease was less severe with a later onset and slower progression than CFA. Surprisingly, the peripheral cytokine profile revealed similar numbers of Th1 and Th17 cells for both CFA and CRA-immunized mice; however, the number of Th1 and Th17 cells was significantly reduced in the CNS of CRA-immunized mice. The development of EAE in CRA-immunized mice was associated with epitope spreading. The unique clinical course of CRA immunizations helps serve as a useful alternative model for studying EAE pathogenesis and potential therapeutics for MS.     

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.     

Neonatal induction of myelin-specific Th1/Th17 immunity does not result in experimental autoimmune encephalomyelitis and can protect against the disease in adulthood

The neonatal immune system is believed to be biased towards T helper type 2 (Th2) immunity, but under certain conditions neonates can also develop Th1 immune responses. Neonatal Th2 immunity to myelin antigens is not pathogenic and can prevent induction of experimental autoimmune encephalomyelitis (EAE) in adulthood, but the consequences of neonatally induced Th1 immunity to self-antigens have remained unresolved. Here, we show that neonatal injection of mice with myelin antigens emulsified in complete Freund's adjuvant (CFA) induced vigorous production of IFN-gamma and IL-17, but not IL-5, consistent with myelin-specific Th1/Th17 immunity. Importantly, the myelin-specific Th1/Th17 cells persisted in the mice until adulthood without causing symptoms of EAE. Intraperitoneal, but not subcutaneous injection of neonates with myelin antigens protected against induction of EAE as adults. Intraperitoneally injected neonates showed a substantial decrease of the number and avidity of myelin-reactive Th17 cells, suggesting a decrease in IL-17 producing precursor cells as the mechanism of protection from EAE upon re-injection with myelin antigens as adults. The results could provide a rationale for the presence of autoreactive T cells found in healthy human individuals without autoimmune disease.     

Behavioral investigation of mice with experimental autoimmune encephalomyelitis

Multiple sclerosis is a neuroinflammatory disease that results in serious neurological disability. Besides physical impairment, behavioral symptoms are also common in patients with multiple sclerosis. Experimental autoimmune encephalomyelitis (EAE) is considered to be a model of multiple sclerosis and mimics the main features of the disease, such as demyelination and motor impairment. In this work, we aimed to study behavioral parameters in animals with EAE using the MOG(35-55) model in C57BL/6 mice. We analyzed memory and anxiety in animals using the elevated plus maze, the step down inhibitory avoidance task and the memory recognition test. No differences in any tests were found when comparing controls and animals induced with EAE. Therefore, we conclude that behavioral changes in animals with EAE induced with MOG(35-55) are probably subtle or absent.     

Mice devoid of Tau have increased susceptibility to neuronal damage in myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis

The abundant axonal microtubule-associated protein tau regulates microtubule and actin dynamics, thereby contributing to normal neuronal function. We examined whether mice deficient in tau (Tau(-/-)) or with high levels of human tau differ from wild-type (WT) mice in their susceptibility to neuroaxonal injury in experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. After sensitization with MOG35-55, there was no difference in clinical disease course between human tau and WT mice, but Tau mice had more severe clinical disease and significantly more axonal damage in spinal cord white matter than those in WT mice. Axonal damage in gray matter correlated with clinical severity in individual mice. By immunoblot analysis, the early microtubule-associated protein-1b was increased 2-fold in the spinal cords of Tau mice with chronic experimental autoimmune encephalomyelitis versus naive Tau mice. This difference was not detected in comparable WT animals, which suggests that there was compensation for the loss of tau in the deficient mice. In addition, levels of the growth arrest-specific protein 7b, a tau-binding protein that is stabilized when bound to tau, were higher in WT than those in Tau(-/-) spinal cord samples. These data indicate that loss of tau exacerbates experimental autoimmune encephalomyelitis and suggest that maintaining tau integrity might reduce the axonal damage that occurs in inflammatory neurodegenerative diseases such as multiple sclerosis.     

Infiltration of Th1 and Th17 cells and activation of microglia in the CNS during the course of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a mouse model for multiple sclerosis, where disease is mediated by autoantigen-specific T cells. Although there is evidence linking CD4⁺ T cells that secrete IL-17, termed Th17 cells, and IFN-γ-secreting Th1 cells with the pathogenesis of EAE, the precise contribution of these T cell subtypes or their associated cytokines is still unclear. We have investigated the infiltration of CD4⁺ T cells that secrete IFN-γ, IL-17 or both cytokines into CNS during development of EAE and have examined the role of T cells in microglial activation. Our findings demonstrate that Th17 cells and CD4⁺ T cells that produce both IFN-γ and IL-17, which we have called Th1/Th17 cells, infiltrate the brain prior to the development of clinical symptoms of EAE and that this coincides with activation of CD11b⁺ microglia and local production of IL-1β, TNF-α and IL-6 in the CNS. In contrast, significant infiltration of Th1 cells was only detected after the development of clinical disease. Co-culture experiments, using mixed glia and MOG-specific T cells, revealed that T cells that secreted IFN-γ and IL-17 were potent activators of pro-inflammatory cytokines but T cells that secrete IFN-γ, but not IL-17, were less effective. In contrast both Th1 and Th1/Th17 cells enhanced MHC-class II and co-stimulatory molecule expression on microglia. Our findings suggest that T cells which secrete IL-17 or IL-17 and IFN-γ infiltrate the CNS prior to the onset of clinical symptoms of EAE, where they may mediate CNS inflammation, in part, through microglial activation.     

Protective DNA vaccination against experimental autoimmune encephalomyelitis is associated with induction of IFNbeta

DNA vaccines encoding encephalitogenic peptides protect against subsequent development of rat experimental autoimmune encephalomyelitis (EAE) through unknown mechanisms. We investigated immune cell phenotypes at different time points after DNA vaccination with vaccine encoding myelin oligodendrocyte glycoprotein peptide 91-108 and subsequent induction of EAE. In protected rats, we observed (i) no alterations in antigen-specific Th2 or Th3 responses, (ii) reduced MHC II expression on splenocytes early after EAE induction, (iii) antigen-specific upregulation of IFNbeta upon recall stimulation and (iv) reduced IL-12Rbeta2 on lymphocytes. We suggest that the underlying mechanism of DNA vaccination is associated with immunomodulation exerted by induced IFNbeta.