Celastrol suppresses experimental autoimmune encephalomyelitis via MAPK/SGK1-regulated mediators of autoimmune pathology

Inflammation Research - Multiple sclerosis (MS) is a debilitating autoimmune disease involving immune dysregulation of the pathogenic T helper 17 (Th17) versus protective T regulatory (Treg) cell...     

Eotaxin-2 blockade ameliorates experimental autoimmune encephalomyelitis

AIM: To study the effect of blocking the eo-2 pathway on the development and severity of experimental autoimmune encephalomyelitis (EAE). METHODS: We produced mAb directed against eo-2, named D8. MOG35-55 induced-EAE mice were daily intravenously injected with either 25 μg or 100 μg D8, or with vehicle control alone [phosphate-buffered saline (PBS)], starting from day 0 post immunization and were monitored for EAE clinical score (n = 10 in each group). Mice were sacrificed on day 58 and their sera were assessed for the presence of anti-myelin oligodendrocyte glycoprotein (anti-MOG) antibodies autoantibodies, as well as for the profile of pro-inflammatory cytokines and chemokines. Histological analysis of brain sections was performed by hematoxylin and eosin staining. RESULTS: Daily treatment of EAE induced mice with D8 significantly decreased the severity of EAE symptoms. Treatment with both concentrations of D8 ameliorated EAE symptoms compared to PBS treated mice, starting from day 42 post immunization (0.89 ± 0.35 in D8 25 μg and D8 100 μg treated groups vs 2.11 ± 0.38 in the PBS treated group, P = 0.03). A significant improvement in EAE clinical score compared to total IgG treated mice was observed with the higher concentration of D8 (0.81 ± 0.38 in D8 100 μg treated group vs 2.11 ± 0.31 in IgG1 treated group, on day 56 post immunization, P = 0.04). D8 treated mice with EAE did not significantly exhibit lower sera levels of anti-MOG autoantibodies compared to IgG-treated mice. However, they expressed lower sera levels of the pro-inflammatory cytokines: tumor necrosis factor (7.8 ± 0.2 pg/mL in D8 100 μg treated mice vs 19.9 ± 3.4 pg/mL in IgG treated mice, P = 0.005) and interferon-gamma (1.4 ± 0.6 pg/mL in D8 100 μg treated mice vs 3.6 ± 0.4 pg/mL in IgG treated mice, P = 0.02), as well as reduced levels of the chemokine macrophage chemoattractant protein-1 (27.2 ± 3.1 pg/mL in D8 100 μg treated mice vs 63.7 ± 12.3 pg/mL in IgG treated mice, P = 0.03). These findings indicate that blocking the eo-2 pathway in EAE may affect not only eosinophil infiltration into the central nervous system (CNS), but also have an effect on monocytes and T cells, but not humoral, mediated responses. Histological analysis of the brains of D8 treated mice with EAE support that this treatment decreases immune cells infiltrates in the CNS. CONCLUSION: Taken together, these findings suggest a role for eo-2 in EAE pathogenesis and consequentially may support a therapeutic potential of anti-eo-2 neutralizing mAb in multiple sclerosis.     

Interleukin-27 suppresses experimental autoimmune encephalomyelitis during bone marrow stromal cell treatment

Interleukin (IL)-17 is a key inflammatory cytokine in autoimmune disease and may play an important role in the development of experimental autoimmune encephalomyelitis (EAE). In this study, we observed decreased IL-17 and increased IL-27 in EAE rats treated with bone marrow stromal cells (BMSCs). Neutralization of IL-27 resulted in recovery of the BMSCs effect. Adoptive transfer induction of EAE was poor by BMSC-stimulated MNCs, but could be induced by MNCs stimulated by BMSCs under blockade of IL-27 signaling. These results demonstrate that BMSCs may suppress the development of EAE, possibly via secretion of IL-27, which can inhibit IL-17 production or Th17 cell generation.     

Blockade of TREM-2 exacerbates experimental autoimmune encephalomyelitis

Triggering receptor expressed on myeloid cells (TREM-2) is a membrane receptor associated with DAP12 that is expressed primarily in myeloid cells, including dendritic cells and microglia, and promotes fusion of osteoclast precursors into multinucleated cells. A rare autosomal recessive condition, Nasu-Hakola disease (NHD) is associated with loss-of-function mutations in DAP12 and TREM-2. The brain pathology observed in NHD patients suggests that disruption of the TREM-2/DAP12 pathway leads to neurodegeneration with demyelination and axonal loss. In this study, we have characterized TREM-2 protein expression on microglia using a newly produced monoclonal antibody directed against the mouse TREM-2 receptor. We report that TREM-2 expression is up-regulated in the spinal cord during both the early inflammatory and chronic phases of myelin oligodendrocyte glycoprotein (MOG)(35-55)peptide-induced experimental autoimmune encaphalomyelitis (EAE). We also demonstrate that TREM-2 is highly expressed on microglial cells in the central nervous system (CNS) during EAE and that blockade of TREM-2 during the effector phase of EAE results in disease exacerbation with more diffuse CNS inflammatory infiltrates and demyelination in the brain parenchyma. These results demonstrate a critical role for TREM-2 during inflammatory responses in the CNS.     

Modulation of experimental autoimmune encephalomyelitis by VLA-2 blockade

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). Adhesion molecules play important roles in cell-cell and cell-extracellular matrix (ECM) interactions in inflammation. Blocking the interaction between inflammatory cells and vascular endothelia can prevent cell entry into tissues and harmful inflammatory responses, that is, autoimmunity, but could also limit immunosurveillance by anti-viral T cells in sites of infection or latency. Development of progressive multifocal leukoencephalopathy in patients treated with antibody against very late antigen (VLA)-4 prompted us to explore an alternative therapeutic approach. We used an antibody against the integrin alpha2, VLA-2, that interacts with ECM, not vascular endothelium. SJL/J mice were sensitized with myelin proteolipid protein (PLP)(139-151) peptide to induce experimental autoimmune encephalomyelitis (EAE), an animal model for MS. Treatment of mice with VLA-2 antibody suppressed clinical signs and CNS inflammation of EAE, when antibody was given immediately after disease onset. In contrast, VLA-4 or VLA-2 antibody treatment of mice during the priming or remission phase of EAE had minor effects on the disease's clinical course. No differences were found in lymphoproliferative responses to PLP(139-151) among treatment groups. Data suggest that blocking cell-ECM interactions can be an alternative therapy for MS.     

A BAFF antagonist suppresses experimental autoimmune encephalomyelitis by targeting cell-mediated and humoral immune responses

BAFF [B cell-activating factor of the tumour necrosis factor (TNF) family] and APRIL (a proliferation-inducing ligand) are two TNF family members with shared receptors. While, physiological roles for APRIL are not fully understood, BAFF is critical for B cell homeostasis and also acts as a co-stimulator of T cells. Using a B and T cell-mediated mouse model of multiple sclerosis (MS), myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), we observed that a BAFF/APRIL antagonist (soluble BCMA-Fc) inhibited central nervous system inflammation and demyelination such that it suppressed the onset and progression of clinical symptoms of EAE. In addition to dramatically reducing the titre of MOG-specific auto-antibodies, this treatment also induced a switch in the subtype of the T(h) cell population characterized by marked alterations in cytokine production following re-stimulation with MOG in vitro. Indeed, hBCMA-Fc therapy led to significant increases in the level of transforming growth factor beta, while the levels of T(h)1 cytokines were markedly diminished. These results not only identify BAFF as a critical factor in maintaining humoral immunity in EAE but also support its role in T lymphocyte responses. Our findings demonstrate that hBCMA-Fc acts on both effector arms of the immune response in EAE, a characteristic that may be of significant therapeutic value in the treatment of MS.     

Uncoupling protein 2 has protective function during experimental autoimmune encephalomyelitis

Uncoupling protein 2 (UCP2) is a member of the mitochondrial transporter superfamily that is expressed in many tissues, including immune cells. UCP2 prevents oxidative stress by reducing reactive oxygen species. Using UCP2-deficient mice, it was shown that UCP2 is involved in the regulation of insulin secretion, in the resistance to infection, and in atherosclerosis. Here, we investigated the role of UCP2 in experimental autoimmune encephalomyelitis, a murine model of multiple sclerosis. Immunized C57BL/6J UCP2-deficient mice showed a slightly delayed onset during experimental autoimmune encephalomyelitis (13.0 +/- 0.6 versus 11.5 +/- 0.8 in wild-type controls) and developed significantly higher disease scores than littermate controls (maximum disease score of 2.9 +/- 0.2 versus 1.7 +/- 0.2, P = 0.001). Higher levels of infiltrating T cells into the spinal cord meninges and parenchyma were observed. The T-cell proliferative response to the specific antigen was increased in UCP2-deficient mice compared with littermate controls, and CD4 cells of UCP2 knockout mice produced significantly higher levels of pro-inflammatory cytokines, eg, tumor necrosis factor-alpha and interleukin-2, resulting from a Th1 response. Mice lacking UCP2 also developed a higher B-cell response. Concomitantly, CD4 and CD8 cells of the UCP2-deficient mice showed increased production of reactive oxygen species. These results suggest a protective function of UCP2 in chronic inflammatory diseases such as multiple sclerosis.     

Vaccination against IL-17 suppresses autoimmune arthritis and encephalomyelitis

Interleukin 17 is a T cell-derived cytokine that induces the release of pro-inflammatory mediators in a wide range of cell types. Recently, a subset of IL-17-producing T helper cells (Th17) distinct from Th1 and Th2 cells has been described, which constitutes a new T cell polarization state. Aberrant Th17 responses and overexpression of IL-17 have been implicated in a number of autoimmune disorders including rheumatoid arthritis and multiple sclerosis. Molecules blocking IL-17 such as IL-17-specific monoclonal antibodies have proved to be effective in ameliorating disease in animal models. Hitherto, active immunization targeting IL-17 is an untried approach. Herein we explore the potential of neutralizing IL-17 by active immunization using virus-like particles conjugated with recombinant IL-17 (IL-17-VLP). Immunization with IL-17-VLP induced high levels of anti-IL-17 antibodies thereby overcoming natural tolerance, even in the absence of added adjuvant. Mice immunized with IL-17-VLP had lower incidence of disease, slower progression to disease and reduced scores of disease severity in both collagen-induced arthritis and experimental autoimmune encephalomyelitis. Active immunization against IL-17 therefore represents a novel therapeutic approach for the treatment of chronic inflammatory diseases.     

Propofol hemisuccinate suppression of experimental autoimmune encephalomyelitis

Propofol hemisuccinate is a prodrug water soluble form of the lipophilic, phenolic compound propofol (2,6-di-isopropylphenol), that is the active ingredient in the widely used anesthetic agent Diprovan. Propofol binds to GABA_A receptors but also has a phenolic structure that confers antioxidant properties to the molecule. The effects of propofol hemisuccinate in rat experimental autoimmune encephalomyelitis (EAE) were studied using different doses and time regimes. Propofol hemisuccinate, 100 mg/kg given three times a day from day 7 or day 12 until day 16 after disease initiation, significantly reduced maximal EAE score. Histology studies supported the clinical findings demonstrating reduction in the inflammatory response in the lumbar spinal cord in animals treated with propofol hemisuccinate. Decreased levels of nitrotyrosine and unchanged levels of induced nitric oxide synthase suggest propofol hemisuccinate crossed the blood brain barrier and exerted its effects by lowering reactive oxygen species levels. The results suggest that propofol hemisuccinate may provide an alternative mode of treatment for acute exacerbations of multiple sclerosis.     

Propofol hemisuccinate suppression of experimental autoimmune encephalomyelitis

Propofol hemisuccinate is a prodrug water soluble form of the lipophilic, phenolic compound propofol (2,6-di-isopropylphenol), that is the active ingredient in the widely used anesthetic agent Diprovan. Propofol binds to GABA(A) receptors but also has a phenolic structure that confers antioxidant properties to the molecule. The effects of propofol hemisuccinate in rat experimental autoimmune encephalomyelitis (EAE) were studied using different doses and time regimes. Propofol hemisuccinate, 100 mg/kg given three times a day from day 7 or day 12 until day 16 after disease initiation, significantly reduced maximal EAE score. Histology studies supported the clinical findings demonstrating reduction in the inflammatory response in the lumbar spinal cord in animals treated with propofol hemisuccinate. Decreased levels of nitrotyrosine and unchanged levels of induced nitric oxide synthase suggest propofol hemisuccinate crossed the blood brain barrier and exerted its effects by lowering reactive oxygen species levels. The results suggest that propofol hemisuccinate may provide an alternative mode of treatment for acute exacerbations of multiple sclerosis.     

Neuroprotective role of fibroblast growth factor-2 in experimental autoimmune encephalomyelitis

The role of fibroblast growth factor-2 (FGF-2) in multiple sclerosis and its animal model experimental autoimmune encephalomyelitis is discussed. This study is the first to use FGF-2(-/-) mice to further address the involvement of FGF-2 in the disease process. We demonstrate that immunization with myelin oligodendrocyte glycoprotein peptide 35-55 induces more severe experimental autoimmune encephalomyelitis in FGF-2(-/-) mice compared with FGF-2(+/+) mice. The antigen-specific cytokine response to myelin oligodendrocyte glycoprotein peptide and the degree of central nervous system inflammation was similar in both groups. However, FGF-2(-/-) mice displayed increased infiltration of CD8(+) T cells and macrophages/microglia. In addition, nerve fibre degeneration and axonal loss were augmented, whereas the extent of remyelination in central nervous system lesions was reduced. FGF-2 has been associated with the induction of demyelination and the inhibition of myelin production by oligodendrocytes. Our study supports the opposing notion that FGF-2 can also assert a neuroprotective function. This may be particularly appealing when it comes to targeting the neurodegenerative aspect of multiple sclerosis.     

Chronic calorie restriction attenuates experimental autoimmune encephalomyelitis

Calorie restriction (CR) prevents many age-associated diseases and prolongs the lifespan. CR induces multiple metabolic and physiologic modifications, including anti-inflammatory, antioxidant, and neuroprotective effects that may be beneficial in multiple sclerosis (MS). The present studies sought to determine whether CR or increased calorie intake alters the course of experimental autoimmune encephalomyelitis (EAE), the leading animal model for MS. SJL and C57BL/6 mice were subjected to 40% CR beginning at 5 weeks of age. After 5 weeks of CR, EAE was induced by immunizing with proteolipid protein in SJL mice and with myelin oligodendrocyte glycoprotein in C57BL/6 mice. Clinical, histologic, and immunologic features of EAE were compared with mice fed ad libitum and to SJL mice fed a high-fat, high-calorie diet. CR ameliorated clinical EAE in both mouse strains with less severe inflammation, demyelination, and axon injury. No suppression of immune function was observed. A high-calorie diet did not alter the EAE course. CR was associated with increased plasma levels of corticosterone and adiponectin and reduced concentrations of IL-6 and leptin. The CR-induced hormonal, metabolic, and cytokine changes observed in our studies suggest a combined anti-inflammatory and neuroprotective effect. CR with adequate nutrition and careful medical monitoring should be explored as a potential treatment for MS.     

Epitope-specific immune tolerization ameliorates experimental autoimmune encephalomyelitis

The availability of glatiramer acetate (GA) for inducing immune tolerance is a significant advancement in the treatment of multiple sclerosis (MS). However, a sizable proportion of patients maintain active disease, regardless of treatment. Another approach to induce T-cell tolerance is therefore still an unmet medical need.     

Critical role for PDE4 subfamilies in the development of experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an animal model of multiple sclerosis exhibiting neuroinflammation, axonal damage and demyelination, further characterized by T- and B-cell responses to myelin oligodendrocyte glycoprotein. Pharmacological manipulation of phosphodiesterases (PDEs) provokes profound anti-inflammatory responses through modulation of cAMP levels. The PDE4B subfamily has been related to the inflammatory immune response in mice and PDE4 inhibition produces amelioration of the clinical signs and delayed onset in the EAE model. Analyses of the expression of the mRNA coding for PDE4B splice variants revealed an upregulation of PDE4B2 in the brainstem and spinal cord of EAE mice which correlated with forkhead box P3 (FoxP3) and transforming growth factor beta (TGF-β) mRNAs expression in a score-dependent manner. The increase observed for the PDE4B protein was mainly found in antigen-presenting cells (APCs) such as dendritic cells and microglia/macrophages, in areas with high cellular infiltration. Unexpectedly, PDE4B^−/− mice showed an earlier onset of the disease compared to wildtype mice. The results point to a possible role of the PDE4B enzyme and in particular the PDE4B2 splice variant during EAE pathogenesis, probably by modulating cAMP levels in APCs, consequently influencing the cytokine environment important for T-cell differentiation.     

Bax-ablation attenuates experimental autoimmune encephalomyelitis in mice

Multiple sclerosis (MS) is an inflammatory disease of the central nervous system characterized by demyelination and axonal damage. Although the exact pathophysiology is unknown, apoptosis plays a crucial role. Here, we studied the role of the pro-apoptotic gene Bax in myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), the animal model for MS. We demonstrate that the clinical signs were markedly reduced in the EAE Bax-deficient mice as compared to wild type (2.3 +/- 0.5 vs. 1.02 +/- 0.32, respectively, P < 0.05). Bax-deficient mice demonstrated less inflammatory infiltration and axonal damage, although they showed similar T-cell immune potency. In conclusion, ablation of the bax gene attenuates the severity of MOG-induced EAE and emphasizes the importance of apoptosis in the pathogenesis of EAE and MS.     

Streptococcus pneumoniae Infection aggravates experimental autoimmune encephalomyelitis via Toll-like receptor 2

The course of autoimmune inflammatory diseases of the central nervous system (CNS) can be influenced by infections. Here we assessed the disease-modulating effects of the most frequent respiratory pathogen Streptococcus pneumonia on the course of experimental autoimmune encephalomyelitis (EAE). Mice were immunized with myelin oligodendrocyte glycoprotein 35-55 (MOG(35-55)) peptide, challenged intraperitoneally with live S. pneumoniae type 3, and then treated with ceftriaxone. EAE was monitored by a clinical score for 35 days after immunization. EAE was unaltered in mice infected with S. pneumoniae 2 days before and 21 days after the first MOG(35-55) injection but was more severe in animals infected 7 days after the first MOG(35-55) injection. The antigen-driven systemic T-cell response was unaltered, and the intraspinal Th1 cytokine mRNA concentrations at the peak of disease were unchanged. The composition of CNS-infiltrating cells and subsequent tissue destruction were only slightly increased after S. pneumoniae infection. In contrast, the serum levels of tumor necrosis factor alpha and interleukin-6 and spinal interleukin-6 levels were elevated, and the expression of major histocompatibility complex class II molecules, CD80, and CD86 on splenic dendritic cells were enhanced early after infection. Serum cytokine concentrations were not elevated, and EAE was not aggravated by S. pneumoniae infection in Toll-like receptor 2 (TLR2)-deficient mice. In conclusion, infection with S. pneumoniae worsens EAE probably by elevation of proinflammatory cytokines and activation of dendritic cells in the systemic circulation via TLR2 and cross talk through the blood-brain barrier.