Delayed Experimental Autoimmune Encephalomyelitis Onset Research Articles

Immunobiology of lymphotoxin: role in a mouse model of multiple sclerosis

Complex immunobiology of lymphotoxin (LTα) is due to multiple modalities of signal transduction, involving a soluble homotrimer and membrane-bound heterotrimers that engage at least three different receptors. While LTα is crucial for the formation and maintenance of secondary lymphoid organs, its overproduction is observed in autoimmune diseases such as rheumatoid arthritis and multiple sclerosis. Initially, LTα was considered pathogenic in the development of experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis, as demonstrated by the resistance of mice with genetic LTα inactivation to EAE induction. However, conflicting observations arose when EAE was induced in RAG1-deficient mice that underwent adoptive bone marrow transfer from LTα-deficient mice, thereby calling into question previous conclusions about the role of LTα in EAE development.
 This study aimed to investigate the role of LTα in MOG35-55-induced EAE using mice deficient in LTα or its membrane receptor, LTβR. LTα knockout mice used here were designed to avoid the artifact involving TNF gene downregulation in myeloid cells, which occurred in the conventional LTα knockout mice.
 Surprisingly, LTα-deficient mice with normal TNF expression developed EAE clinically comparable to wild-type mice. Conversely, genetic inactivation of LTβR delayed EAE onset. However, during the later stages of the disease, LTβR deletion exacerbated clinical symptoms of EAE.
 These findings demonstrate that the involvement of LTα in EAE development is more complex than previously estimated, and that LTβR exhibits diverse functions depending on the disease stage: pathogenic at the early stage and protective at the later stages of EAE.

Pterostilbene Protects the Optic Nerves and Retina in a Murine Model of Experimental Autoimmune Encephalomyelitis via Activation of SIRT1 Signaling

Optic neuritis and retinal damage are common manifestations of multiple sclerosis (MS). Pterostilbene (PT) has been used to treat multiple diseases for its anti-inflammatory, anti-apoptosis and neuroprotective activities. This study aimed to investigate whether PT exerts a therapeutic effect on optic neuritis and retinal damage triggered by MS. Here, experimental autoimmune encephalomyelitis (EAE), an experimental model for MS, was induced in female C57BL/6 mice by immunizing with MOG35-55 peptide and treating with pertussis toxin. The mice were intraperitoneally injected with 20 mg/kg and 40 mg/kg PT once daily for 25 days at 24 h post immunization. We found that PT alleviated EAE severity and delayed EAE onset. Moreover, PT mitigated EAE-induced optic nerves and retinal inflammation, as indicated by the decreased Iba-1+ and GFAP+ cells and mRNA levels of interleukin-6, tumor necrosis factor-α and interleukin-1β and the increased Iba-1+sirtuin 1 (SIRT1)+ and GFAP+SIRT1+ cells in the optic nerves and retina. PT also protected the optic nerves against demyelination and axonal loss and the retina against disorders in retinal morphology and apoptosis of retinal ganglion cells. High-dose PT had a more significant effect on protection of the optic nerves and retina in EAE than low-dose PT. In addition, PT activated SIRT1 signaling in the optic nerves and retina. Notably, EX-527, an inhibitor of SIRT1, reversed the effect of high-dose PT on the optic nerves and retina, indicating that PT exerted the protective effect via activating SIRT1 signaling. This study provides a potential candidate for treating MS.

PD-1 Blockade Reverses Obesity-Mediated T Cell Priming Impairment.

Despite obesity reaching pandemic proportions, its impact on antigen-specific T cell responses is still unclear. We have recently demonstrated that obesity results in increased expression of PD-1 on T cells, and checkpoint blockade targeting PD-1/PD-L1 surprisingly resulted in greater clinical efficacy in cancer therapy. Adverse events associated with this therapy center around autoimmune reactions. In this study, we examined the impact of obesity on T cell priming and on autoimmune pathogenesis using the mouse model experimental autoimmune encephalomyelitis (EAE), which is mediated by autoreactive myelin-specific T cells generated after immunization. We observed that diet-induced obese (DIO) mice had a markedly delayed EAE onset and developed milder clinical symptoms compared to mice on control diet (CD). This delay was associated with impaired generation of myelin-specific T cell numbers and concurrently correlated with increased PD-L1 upregulation on antigen-presenting cells in secondary lymphoid organs. PD-1 blockade during the priming stage of EAE restored disease onset and severity and increased numbers of pathogenic CD4+ T cells in the central nervous system (CNS) of DIO mice to similar levels to those of CD mice. Administration of anti–PD-1 after onset of clinical symptoms did not increase EAE pathogenesis demonstrating that initial priming is the critical juncture affected by obesity. These findings demonstrate that obesity impairs antigen-specific T cell priming, but this can be reversed with PD-1 blockade. Our results further suggest that PD-1 blockade may increase the risk of autoimmune toxicities, particularly in obesity.

Efficacy and mechanism of Wuzi Yanzong pill in the treatment of EAE

Wuzi Yanzong Pill (WYP, a classical Chinese herbal formula) has a potential therapeutic effect on experimental autoimmune encephalomyelitis (EAE), but the mechanism is not clear. To determine the therapeutic effect of WYP in EAE, and explore its mechanism. C57BL/6 mice were randomly divided into control, EAE, and high/medium/low dose WYP groups. Mice received WYP twice daily from 7 days before immunization to 14 and 28 days post immunization (p.i.) (high/medium/low dose =16/8/4 g/kg). At days 14 and 28 p.i., spinal cord and spleen were obtained. WYP treatment delayed EAE onset and relieved the severity of EAE accompanied by the inhibition of inflammatory cell infiltration and the improvement of demyelination in spinal cord. WYP treatment may more effectively induce M2 macrophage polarization that was related with decreased IFN-γ, IL-17 and TNF-α. WYP treatment also inhibited the expression/activation of ROCK and TLR-4/NF-κB signaling pathway and reduced the expression of MCP-1 and CCR-2 in brain, spinal cord and spleen compared to EAE control. Provides an experimental basis for further clinical application of WYP for the treatment of MS. (NNSF of China 81102552 and 81703978, Shanxi Scholarship Council project 2017-129 and 2017-19, Shanxi International Science and Technology cooperation project 201703D421016, Scientific and technological innovation team of integrated Chinese and western medicine for the prevention and treatment on nervous system diseases of Shanxi university of Chinese medicine 2018TD-012, Shanxi Key Laboratory project SXIDL-2018-04, Shanxi Key project 201803D31209. Ma and Xiao are corresponding authors).

Deficient arginase II expression without alteration in arginase I expression attenuated experimental autoimmune encephalomyelitis in mice.

In the past there have been a multitude of studies that ardently support the role of arginase II (Arg II) in vascular and endothelial disorders; however, the regulation and function of Arg II in autoimmune diseases has thus far remained unclear. Here we report that a global Arg II null mutation in mice suppressed experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. During EAE, both Arg I and Arg II were induced in spinal cords, but only Arg II was induced in spleens and splenic dendritic cells (DCs). DC activation by lipopolysaccharide (LPS), CD40L or TLR8 agonist significantly enhanced Arg II expression without affecting Arg I expression. Conversely, DC differentiating cytokines [IL-4 and granulocyte macrophage-colony-stimulating factor (GM-CSF)] yielded opposite effects. In addition, Arg I and Arg II were regulated differentially during Th1 and Th17 cell polarization. Arg II deficiency in mice delayed EAE onset, ameliorated clinical symptoms and reduced myelin loss, accompanied by a remarkable reduction in the EAE-induced spinal cord expression of Th17 cell markers (IL-17 and RORγt). The abundance of Th17 cells and IL-23+ cells in relevant draining lymph nodes was significantly reduced in Arg II knockout mice. In activated DCs, Arg II deficiency significantly suppressed the expression of Th17-differentiating cytokines IL-23 and IL-6. Interestingly, Arg II deficiency did not lead to any compensatory increase in Arg I expression in vivo and in vitro. In conclusion, Arg II was identified as a factor promoting EAE likely via an Arg I-independent mechanism. Arg II may promote EAE by enhancing DC production of Th17-differentiating cytokines. Specific inhibition of Arg II could be a potential therapy for multiple sclerosis.

B cells are required for sunlight protection of mice from a CNS-targeted autoimmune attack

The ultraviolet (UV) radiation contained in sunlight is a powerful immune suppressant. While exposure to UV is associated with protection from the development of autoimmune diseases, particularly multiple sclerosis, the precise mechanism by which UV achieves this protection is not currently well understood. Regulatory B cells play an important role in preventing autoimmunity and activation of B cells is a major way in which UV suppresses adaptive immune responses. Whether UV-protection from autoimmunity is mediated by the activation of regulatory B cells has never been considered before. When C57BL/6 mice were exposed to low, physiologically relevant doses of UV, a unique population of B cells was activated in the skin draining lymph nodes. As determined by flow cytometry, CD1dlowCD5–MHC-IIhiB220hi UV-activated B cells expressed significantly higher levels of CD19, CD21/35, CD25, CD210 and CD268 as well as the co-stimulatory molecules CD80, CD86, CD274 and CD275. Experimental autoimmune encephalomyelitis (EAE) in mice immunized with MOG/CFA was reduced by exposure to UV. UV significantly inhibited demyelination and infiltration of inflammatory cells into the spinal cord. Consequently, UV-exposed groups showed elevated IL-10 levels in secondary lymphoid organs, delayed EAE onset, reduced peak EAE score and significantly suppressed overall disease incidence and burden. Importantly, protection from EAE could be adoptively transferred using B cells isolated from UV-exposed, but not unirradiated hosts. Indeed, UV-protection from EAE was dependent on UV activation of lymph node B cells because UV could not protect mice from EAE who were pharmacologically depleted of B cells using antibodies. Thus, UV maintenance of a pool of unique regulatory B cells in peripheral lymph nodes appears to be essential to prevent an autoimmune attack on the central nervous system.

Lung inflammation stalls Th17-cell migration en route to the central nervous system during the development of experimental autoimmune encephalomyelitis.

Recruiting pathogenic T cells to the central nervous system (CNS) is a critical step during the development of experimental autoimmune encephalomyelitis (EAE). Here, we report that the absence of autophagy and microtubule-associated protein 1A/1B-light chain 3-associated phagocytosis significantly delayed the onset of EAE in Atg7 conditional knockout (Atg7 CKO) mice in myeloid cells. T-helper cell-cell priming appeared to be normal in the Atg7 CKO mice, but the mice showed significant accumulation of Th17 cells in the lung. The data suggested that the stalling of Th17 cells in the lung en route to the CNS caused the delay. The lung of Atg7 CKO mice, in which we previously demonstrated spontaneous mild inflammation, showed high expression of CCL20, a chemokine that attracts Th17 cells. We have also shown that LPS intranasal instillation delayed EAE onset, suggesting that pulmonary inflammation has an impact on EAE development. Based on our data, therapeutic immunomodulation targeted to the lung, rather than systemically, might be a possible future option to treat multiple sclerosis.

The motorized RhoGAP myosin IXb (Myo9b) in leukocytes regulates experimental autoimmune encephalomyelitis induction and recovery.

Myo9b regulates leukocyte migration by controlling RhoA signaling. Here we assessed its role in active experimental autoimmune encephalomyelitis (EAE). Myo9b(-/-) mice show a delay in the onset of EAE symptoms. The delay in disease onset was accompanied by reduced numbers of Th1 and Th17 cells in the CNS. Myo9b(-/-) mice showed no recovery from disease symptoms and exhibited elevated numbers of both Th17 cells and CD11b+ macrophages. Bone marrow chimeric mice demonstrated that the absence of a leukocyte source of Myo9b was responsible for the delayed leukocyte infiltration into the CNS, delayed EAE onset and lack of recovery.

Inhibition of Hyaluronan Synthesis Protects against Central Nervous System (CNS) Autoimmunity and Increases CXCL12 Expression in the Inflamed CNS

Hyaluronan (HA) may have proinflammatory roles in the context of CNS autoimmunity. It accumulates in demyelinated multiple sclerosis (MS) lesions, promotes antigen presentation, and enhances T-cell activation and proliferation. HA facilitates lymphocyte binding to vessels and CNS infiltration at the CNS vascular endothelium. Furthermore, HA signals through Toll-like receptors 2 and 4 to stimulate inflammatory gene expression. We assessed the role of HA in experimental autoimmune encephalomyelitis (EAE), an animal model of MS by administration of 4-methylumbelliferone (4MU), a well established inhibitor of HA synthesis. 4MU decreased hyaluronan synthesis in vitro and in vivo. It was protective in active EAE of C57Bl/6 mice, decreased spinal inflammatory infiltrates and spinal infiltration of Th1 cells, and increased differentiation of regulatory T-cells. In adoptive transfer EAE, feeding of 4MU to donor mice significantly decreased the encephalitogenicity of lymph node cells. The transfer of proteolipid protein (PLP)-stimulated lymph node cells to 4MU-fed mice resulted in a delayed EAE onset and delayed spinal T-cell infiltration. Expression of CXCL12, an anti-inflammatory chemokine, is reduced in MS patients in CSF cells and in spinal cord tissue during EAE. Hyaluronan suppressed production of CXCL12, whereas 4MU increased spinal CXCL12 in naive animals and during neuroinflammation. Neutralization of CXCR4, the most prominent receptor of CXCL12, by administration of AMD3100 diminished the protective impact of 4MU in adoptive transfer EAE. In conclusion, hyaluronan exacerbates CNS autoimmunity, enhances encephalitogenic T-cell responses, and suppresses the protective chemokine CXCL12 in CNS tissue. Inhibition of hyaluronan synthesis with 4MU protects against an animal model of MS and may represent an important therapeutic option in MS and other neuroinflammatory diseases.

The MAO inhibitor phenelzine improves functional outcomes in mice with experimental autoimmune encephalomyelitis (EAE)

Multiple sclerosis (MS) and the animal model, experimental autoimmune encephalomyelitis (EAE), are both accompanied by motor and non-motor symptoms. Pathological changes in the activities of key neurotransmitters likely underlie many of these symptoms. We have previously described disturbances in the levels of 5-hydroxytryptamine (5-HT/serotonin), noradrenaline (NE) and γ-aminobutyric acid (GABA) in a mouse model of EAE. The potential therapeutic effect of a drug that targets these three neurotransmitters, the antidepressant and anti-panic drug phenelzine (PLZ), was assessed in mice with MOG(35-55) induced EAE. The neurotransmitter content of EAE and control tissue after PLZ administration was first evaluated by HPLC. The ability of PLZ treatment to modulate EAE disease course and clinical signs was then assessed. Daily PLZ treatment, starting seven days after disease induction, delayed EAE onset, reduced disease severity in the chronic phase and was associated with substantial improvements in exploratory behavior and a novel measure of sickness and/or depression. Upon completion of the experiment, PLZ's effects on histopathological markers of the disease were examined. No differences were observed in T cell infiltration, microglia/macrophage reactivity, demyelination or axonal injury in PLZ-treated spinal cords. However, EAE mice treated with PLZ showed a normalization of 5-HT levels in the ventral horn of the spinal cord that might account for the improvements in behavioral outcomes. These results demonstrate the therapeutic potential of MAO inhibitors such as PLZ in MS. Additionally, the behavioral changes observed in EAE mice indicate that alterations in non-motor or 'affective' measures may be valuable to consider in addition to traditional measures of gross locomotor function.

Interleukin-25 Expressed by Brain Capillary Endothelial Cells Maintains Blood-Brain Barrier Function in a Protein Kinase Cϵ-dependent Manner

Interleukin (IL)-25, a member of the IL-17 family of cytokines, is expressed in the brains of normal mice. However, the cellular source of IL-25 and its function in the brain remain to be elucidated. Here, we show that IL-25 plays an important role in preventing infiltration of the inflammatory cells into the central nervous system. Brain capillary endothelial cells (BCECs) express IL-25. However, it is down-regulated by inflammatory cytokines, including tumor necrosis factor (TNF)-alpha, IL-17, interferon-gamma, IL-1beta, and IL-6 in vitro, and is also reduced in active multiple sclerosis (MS) lesions and in the inflamed spinal cord of experimental autoimmune encephalomyelitis, an animal model of MS. Furthermore, IL-25 restores the reduced expression of tight junction proteins, occludin, junction adhesion molecule, and claudin-5, induced by TNF-alpha in BCECs and consequently repairs TNF-alpha-induced blood-brain barrier (BBB) permeability. IL-25 induces protein kinase Cepsilon (PKCepsilon) phosphorylation, and up-regulation of claudin-5 is suppressed by PKCepsilon inhibitor peptide in the IL-25-stimulated BCECs. These results suggest that IL-25 is produced by BCECs and protects against inflammatory cytokine-induced excessive BBB collapse through a PKCepsilon-dependent pathway. These novel functions of IL-25 in maintaining BBB integrity may help us understand the pathophysiology of inflammatory brain diseases such as MS.

Triptolide modulates T‐cell inflammatory responses and ameliorates experimental autoimmune encephalomyelitis

Triptolide (TPT), a diterpenoid triepoxide, is the major component isolated from the Chinese herb Tripterygium wilfordii Hook. f. Previous studies have shown that TPT has immunosuppressive properties and is effective in prolonging graft survival and suppressing autoimmune responses. The aim of this study was to investigate the protective effect of TPT in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. Treatment of C57BL/6 mice with TPT from the date of EAE induction significantly delayed EAE onset and suppressed disease severity, accompanied with reduced inflammation and demyelination in the central nervous system. TPT treatment lead to a significant inhibition of the mRNA expression of both Th1/Th(IL-17) and Th2 cytokines in spleen mononuclear cells (MNC) as well as in spinal cord tissues. In addition, the expression of Forkhead box p3 (Foxp3) was up-regulated in spleen MNC after TPT treatment. Furthermore, we detected apparent inhibition of nuclear factor-kappa B (NF-kappaB)-DNA binding activity, increased expression of the inhibitor of nuclear factor-kappa Balpha (IkappaBalpha) and decreased expression of pIkappaBalpha in spleen MNC in TPT-treated EAE mice. Taken together, these findings indicate that TPT has profound immunoregulatory functions and potential protective values for the treatment of autoimmune inflammatory disorders.

Central nervous system delivery of interleukin 4 by a nonreplicative herpes simplex type 1 viral vector ameliorates autoimmune demyelination.

Multiple sclerosis (MS) is a T cell-mediated organ-specific inflammatory disease leading to central nervous system (CNS) demyelination. On the basis of results obtained in experimental autoimmune encephalomyelitis (EAE) models, MS treatment by administration of antiinflammatory cytokines such as interleukin 4 (IL-4) is promising but is hampered by the limited access of the cytokines to the CNS and by the pleiotropic effects of systemically administered cytokines. We established a cytokine delivery system within the CNS using non-replicative herpes simplex type 1 (HSV-1) viral vectors engineered with cytokine genes. These vectors injected into the cisterna magna (i.c.) of mice diffuse in all ventricular and subarachnoid spaces and infect with high efficiency the ependymal and leptomeningeal cell layers surrounding these areas, without obvious toxic effects. Heterologous genes contained in the vectors are efficiently transcribed in infected ependymal cells, leading to the production of high amounts of the coded proteins. For example, 4.5 ng of interferon gamma (IFN-gamma) per milliliter is secreted into the cerebrospinal fluid (CSF) up to day 28 postinjection (p.i.) and reaches the CNS parenchyma in bioactive form, as demonstrated by upregulation of MHC class I expression on CNS-resident cells. We then exploited the therapeutic potential of the vectors in EAE mice. An HSV-1-derived vector containing the IL-4 gene was injected i.c. in Biozzi AB/H mice at the time of EAE induction. We found the following in treated mice: (1) delayed EAE onset, (2) a significant decrease in clinical score, (3) a significant decrease in perivascular inflammatory infiltrates and in the number of macrophages infiltrating the CNS parenchyma and the submeningeal spaces, and (4) a reduction in demyelinated areas and axonal loss. Peripheral T cells from IL-4-treated mice were not affected either in their antigen-specific proliferative response or in cytokine secretion pattern. Our results indicate that CNS cytokine delivery with HSV-1 vectors is feasible and might represent an approach for the treatment of demyelinating diseases. Advantages of this approach over systemic cytokine administration are the high cytokine level reached in the CNS, the absence of effects on the peripheral immune system, and the long-lasting cytokine production in the CNS after a single vector administration.

Central Nervous System Delivery of Interleukin 4 by a Nonreplicative Herpes Simplex Type 1 Viral Vector Ameliorates Autoimmune Demyelination

Multiple sclerosis (MS) is a T cell-mediated organ-specific inflammatory disease leading to central nervous system (CNS) demyelination. On the basis of results obtained in experimental autoimmune encephalomyelitis (EAE) models, MS treatment by administration of antiinflammatory cytokines such as interleukin 4 (IL-4) is promising but is hampered by the limited access of the cytokines to the CNS and by the pleiotropic effects of systemically administered cytokines. We established a cytokine delivery system within the CNS using nonreplicative herpes simplex type 1 (HSV-1) viral vectors engineered with cytokine genes. These vectors injected into the cisterna magna (i.c.) of mice diffuse in all ventricular and subarachnoid spaces and infect with high efficiency the ependymal and leptomeningeal cell layers surrounding these areas, without obvious toxic effects. Heterologous genes contained in the vectors are efficiently transcribed in infected ependymal cells, leading to the production of high amounts of the coded proteins. For example, 4.5 ng of interferon gamma (IFN-gamma) per milliliter is secreted into the cerebrospinal fluid (CSF) up to day 28 postinjection (p.i.) and reaches the CNS parenchyma in bioactive form, as demonstrated by upregulation of MHC class I expression on CNS-resident cells. We then exploited the therapeutic potential of the vectors in EAE mice. An HSV-1-derived vector containing the IL-4 gene was injected i.c. in Biozzi AB/H mice at the time of EAE induction. We found the following in treated mice: (1) delayed EAE onset, (2) a significant decrease in clinical score, (3) a significant decrease in perivascular inflammatory infiltrates and in the number of macrophages infiltrating the CNS parenchyma and the submeningeal spaces, and (4) a reduction in demyelinated areas and axonal loss. Peripheral T cells from IL-4-treated mice were not affected either in their antigen-specific proliferative response or in cytokine secretion pattern. Our results indicate that CNS cytokine delivery with HSV-1 vectors is feasible and might represent an approach for the treatment of demyelinating diseases. Advantages of this approach over systemic cytokine administration are the high cytokine level reached in the CNS, the absence of effects on the peripheral immune system, and the long-lasting cytokine production in the CNS after a single vector administration.