Characterization of relapsing autoimmune encephalomyelitis and its treatment with decoy chemokine receptor genes

NMR-Based Metabolomics Separates the Distinct Stages of Disease in a Chronic Relapsing Model of Multiple Sclerosis

Relapsing experimental allergic encephalomyelitis (Cr-EAE) is commonly used to explore the pathogenesis and efficacy of new therapies for MS, but it is unclear whether the metabolome of Cr-EAE is comparable to human multiple sclerosis (MS). For MS, the diagnosis and staging can be achieved by metabolomics on blood using a combination of magnetic resonance spectroscopy and partial least squares discriminant analysis (PLS-DA). Here, we sought to discover whether this approach could be used to differentiate between sequential disease states in Cr-EAE and whether the same metabolites would be discriminatory. Urine and plasma samples were obtained at different time-points from a clinically relevant model of MS. Using PLS-DA modelling for the urine samples furnished some predictive models, but could not discriminate between all disease states. However, PLS-DA modelling of the plasma samples was able to distinguish between animals with clinically silent disease (day 10, 28) and animals with active disease (day 14, 38). We were also able to distinguish Cr-EAE mice from naive mice at all-time points and control mice, treated with complete Freund's adjuvant alone, at day 14 and 38. Key metabolites that underpin these models included fatty acids, glucose and taurine. Two of these metabolites, fatty acids and glucose, were also key metabolites in separating relapsing-remitting MS from secondary-progressive MS in the human study. These results demonstrate the sensitivity of this metabolomics approach for distinguishing between different disease states. Furthermore, some, but not all, of the changes in metabolites were conserved in humans and the mouse model, which could be useful for future drug development.

Characterization of CD8-positive macrophages infiltrating the central nervous system of rats with chronic autoimmune encephalomyelitis

CD8+ macrophages appear in the central nervous system (CNS) under various pathological conditions such as trauma and ischemia. Furthermore, macrophages expressing CD8 were found in CNS lesions of chronic, but not acute, experimental autoimmune encephalomyelitis (EAE). To further characterize cells with this phenotype, we examined CD8+ macrophages/monocytes in the CNS and peripheral organs during the course of acute and chronic EAE that had been induced by immunization of rats with myelin basic protein and myelin oligodendrocyte glycoprotein, respectively. Counting CD8+ macrophages in CNS lesions revealed that their numbers increased reaching about 60% of total infiltrating macrophages in chronic EAE, while CD8+ macrophages remained less than 5% throughout the course of acute EAE. Unexpectedly, however, higher abundance of CD8+ monocytes/macrophages in the peripheral blood was found in both acute and chronic EAE. Real-time polymerase chain reaction analysis revealed no significant difference in the levels of chemokines and chemokine receptors of blood CD8+ monocytes between acute and chronic EAE. mRNA expression of perforin, a cytotoxic substance, was up-regulated in CD8+ monocytes compared with that of CD8- monocytes in both acute and chronic EAE. These findings suggest that activated CD8+ macrophages may play a cytotoxic role in chronic EAE lesions and that cells other than CD8+ monocytes/macrophages determined the difference in CNS pathology between acute and chronic EAE. Analysis of CD8+ monocytes/macrophages may provide useful information to permit further dissect the pathomechanisms of multiple sclerosis and to develop effective immunotherapies against autoimmune diseases in the CNS.

Nonviral DNA vaccination augments microglial phagocytosis of beta-amyloid deposits as a major clearance pathway in an Alzheimer disease mouse model

Immunotherapies markedly reduce beta-amyloid (Abeta) burden and reverse behavioral impairment in mouse models of Alzheimer disease. We previously showed that new Abeta DNA vaccines reduced Abeta deposits in Alzheimer disease model mice without detectable side effects. Although they are effective, the mechanisms of Abeta reduction by the DNA vaccines remain to be elucidated. Here, we analyzed vaccinated and control Alzheimer disease model mice from 4 months to 15 months of age to assess which of several proposed mechanisms may underlie the beneficial effects of this vaccination. Immunohistochemical analysis revealed that activated microglial numbers increased significantly in the brains of vaccinated mice after DNA vaccination both around Abeta plaques and in areas remote from them. Microglia in treated mice phagocytosed Abeta debris more frequently than they did in untreated mice. Although microglia had an activated morphological phenotype, they did not produce significant amounts of tumor necrosis factor. Amyloid plaque immunoreactivity and Abeta concentrations in plasma increased slightly in vaccinated mice compared with controls at 9 but not at 15 months of age. Collectively, these data suggest that phagocytosis of Abeta deposits by microglia plays a central role in Abeta reduction after DNA vaccination.

Role of pathogenic T cells and autoantibodies in relapse and progression of myelin oligodendrocyte glycoprotein-induced autoimmune encephalomyelitis in LEW.1AV1 rats

Accumulating evidence suggests that T cells and autoantibodies reactive with myelin oligodendrocyte glycoprotein (MOG) play a critical role in the pathogenesis of multiple sclerosis (MS). In the present study, we have tried to elucidate the pathomechanisms of development and progression of the disease by analysing T cells and autoantibodies in MOG-induced rat experimental autoimmune encephalomyelitis (EAE), which exhibits various clinical subtypes mimicking MS. Analysis using overlapping peptides revealed that encephalitogenic epitopes resided in peptide 7 (P7, residue 91-108) and P8 (residue 103-125) of MOG. Immunization with MOGP7 and MOGP8 induced relapsing-remitting or secondary progressive EAE. T cells taken from MOG-immunized and MOGP7-immunized rats responded to MOG and MOGP7 and sera from MOG-immunized rats reacted to MOG and MOGP1. Significant epitope spreading was not observed at either T-cell or antibody levels. Interestingly, sera from MOGP7-immunized rats with clinical signs did not react to MOG and MOG peptides throughout the observation period, suggesting that disease development and relapse in MOGP7-induced EAE occur without autoantibodies. However, MOGP7 immunization with adoptive transfer of anti-MOG antibodies aggravated the clinical course of EAE only slightly. Analysis of antibodies against conformational epitope (cme) suggests that anti-MOG(cme) may play a role in the pathogenicity of anti-MOG antibodies. Collectively, these findings demonstrated that relapse of a certain type of MOG-induced EAE occurs without autoantibodies but that autoantibodies may play a role in disease progression. Relapses and the progression of MS-mimicking EAE are differently immunoregulated so immunotherapy should be designed appropriately on the basis of precise information.

The dual inhibitor of lipoxygenase and cyclooxygenase ML3000 decreases the expression of CXCR3 ligands

OBJECTIVE

To find previously unknown properties of ML3000, a competitive inhibitor of the cyclooxygenase and the lipoxygenase (LO) pathway.

METHODS

Gene expression of ML3000 treated and untreated rheumatoid arthritis synovial fibroblasts were measured with Affymetrix gene arrays. Downregulation of chemokine (C-X-C motif) ligands CXCL9, CXCL10 and CXCL11 was verified with Real-time polymerase chain reaction, CXCL10 protein levels were determined with ELISA. Rheumatoid arthritis synovial fibroblasts were treated with the cyclooxygenase inhibitor naproxen, the 5-LO inhibitor BWA4C and the 5-lipoxygenase-activating protein (FLAP) inhibitor MK886, and consecutive changes in CXCL10 protein levels measured. 5-LO expression was determined by polymerase chain reaction and Western blot.

RESULTS

In synovial fibroblasts and monocyte-derived macrophages ML3000 inhibited the tumour necrosis factor induced expression of CXCL9, CXCL10 and CXCL11, which are all ligands of the chemokine receptor CXCR3. No effect was observed in monocytes. Whereas inhibition of the cyclooxygenase pathway or the FLAP protein showed no effect, blockade of 5-LO significantly downregulated CXCL10 protein levels. 5-LO mRNA was detected in monocytes and in monocyte-derived macrophages. All tested cell types expressed 5-LO protein.

CONCLUSIONS

ML3000 effectively downregulates CXCR3 ligands. This study confirms that a thorough analysis of the impact of a drug on its target cells cannot only reveal unexpected properties of a substance, but also helps to understand the underlying molecular mechanisms. Accordingly, our data provide the basis for further clinical studies testing the application of ML3000 in diseases such as rheumatoid arthritis or multiple sclerosis.

Differential effects of decoy chemokine (7ND) gene therapy on acute, biphasic and chronic autoimmune encephalomyelitis: implication for pathomechanisms of lesion formation

Multiple sclerosis (MS) exhibits several clinical subtypes such as the relapsing-remitting (RR) and secondary progressive (SP) forms. In accordance with this, formation of demyelinating plaques in the central nervous system (CNS) occurs by different mechanisms. In the present study, we induced acute, biphasic and chronic (RR or SP) EAE in rats and examined the effects of decoy chemokine (7ND) gene therapy, which inhibits the migration of macrophages, to address the above issue. Interestingly, it was demonstrated that the clinical signs of acute EAE and the first attack of biphasic EAE were minimally affected, whereas chronic EAE and the relapse of biphasic EAE were completely suppressed with 7ND treatment. In the CNS, the number of infiltrating macrophages was reduced in all the stages of the three types of EAE. These findings suggest that in acute EAE and in the first attack of biphasic EAE, where anti-macrophage migration therapy was almost ineffective, pathogenic T cells are mainly involved in lesion formation. In contrast, the relapse of biphasic EAE and chronic EAE macrophages play a major role in the disease process. Thus, the mechanisms of lesion formation are not uniform and immunotherapy should be performed on the basis of information about the pathomechanisms of autoimmune diseases.

In vivo administration of plasmid DNA encoding recombinant immunotoxin DT390-IP-10 attenuates experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a T-cell-mediated autoimmune demyelinating disease. The expression of chemokine receptor CXCR3 on activated T cells is crucial to direct the migration of effector cells into the inflammatory sites and initiate EAE. In this study we tested the effect of a novel recombinant immunotoxin targeting CXCR3(+) cells for EAE prevention. The immunotoxin construct DT390-IP-10-SRalpha consisted of interferon gamma-inducible protein 10 (IP-10), a ligand of CXCR3, as the targeting moiety, and a truncated diphtheria toxin (DT390) as the toxic moiety. In vitro transfection of DT390-IP-10-SRalpha into NIH3T3 cells resulted in expression of DT390-IP-10 which proved highly toxic to activated T cells. To evaluate the effect of DT390-IP-10-SRalpha on EAE prevention in vivo, cationic liposome-embedded DT390-IP-10-SRalpha was injected into the muscle of hind limbs of C57BL/6 mice immunized by myelin basic protein (MBP). DT390-IP-10-SRalpha-treated mice showed a delayed onset of EAE and milder symptoms compared to the mice treated with empty control plasmid or PBS alone. Immunohistochemical staining detected significantly reduced infiltrating CXCR3(+) cells in the inflammatory lesions of CNS from immunotoxin treated mice as compared to the controls. This study suggests that targeting CXCR3(+) T cells with recombinant immunotoxin could be achieved in vivo to delay and ameliorate murine EAE.

Chemokines, mononuclear cells and the nervous system: heaven (or hell) is in the details

Chemokines and their receptors are essential elements in leukocyte trafficking during health and disease. There are three (or more) distinct routes of leukocyte entry into the central nervous system (CNS), and molecular mechanisms of physiological and neuroinflammatory leukocyte recruitment to the CNS are slowly coming into view. Migration of immune cells into cerebrospinal fluid supports CNS immunosurveillance. Current knowledge of the trafficking determinants that direct the leukocyte recruitment in CNS pathology relies in large part on studies of multiple sclerosis and its models including experimental autoimmune encephalomyelitis. Overlapping molecular signals are responsible for the migration of specific cells into the CNS during pathological inflammation and host defense, raising challenges and opportunities for therapeutic manipulation.

Chemokine expression by astrocytes plays a role in microglia/macrophage activation and subsequent neurodegeneration in secondary progressive multiple sclerosis

The pathological hallmarks of secondary progressive (SP) multiple sclerosis (MS) include slowly expanding demyelination and axonal damage with less inflammation. To elucidate the pathomechanisms of secondary progressive (SP) multiple sclerosis (MS), we have investigated the expression of chemokines, chemokine receptors, matrix metalloproteinase-9 (MMP-9) and immunoglobulins in the demyelinating plaques. Immunohistochemical analysis revealed that numerous hypertrophic astrocytes were observed at the rim, but not in the center, of the chronic active lesions. Microglia/macrophages phagocytosing myelin debris were also found at the lesion border. In contrast, T cell infiltration was minimal in these plaques. Characteristically, at the rim of the lesions, there were abundant immunoreactivities for monocyte chemoattractant protein-1 (MCP-1)/CCL2 and interferon-gamma inducible protein-10 (IP-10)/CXCL10 and their receptors, CCR2 and CXCR3, while these immunoreactivities were weak in the center, thus forming a chemokine gradient. Double immunofluorescense staining demonstrated that cellular sources of MCP-1/CCL2 and IP-10/CXCL10 were hypertrophic astrocytes and that both astrocytes and microglia/macrophages expressed CCR2 and CXCR3. MMP-9 was also present at the rim of the lesions. These results suggest that MCP-1/CCL2 and IP-10/CXCL10 produced by astrocytes may activate astrocytes in an autocrine or paracrine manner and direct reactive gliosis followed by migration and activation of microglia/macrophages as effector cells in demyelinating lesions. Targeting chemokines in SPMS may therefore be a powerful therapeutic approach to inhibit lesional expansion.

Nonviral Abeta DNA vaccine therapy against Alzheimer's disease: long-term effects and safety

It was recently demonstrated that amyloid beta (Abeta) peptide vaccination was effective in reducing the Abeta burden in Alzheimer model mice. However, the clinical trial was halted because of the development of meningoencephalitis in some patients. To overcome this problem, anti-Abeta antibody therapy and other types of vaccination are now in trial. In this study, we have developed safe and effective nonviral Abeta DNA vaccines against Alzheimer's disease. We administered these vaccines to model (APP23) mice and evaluated Abeta burden reduction. Prophylactic treatments started before Abeta deposition reduced Abeta burden to 15.5% and 38.5% of that found in untreated mice at 7 and 18 months of age, respectively. Therapeutic treatment started after Abeta deposition reduced Abeta burden to approximately 50% at the age of 18 months. Importantly, this therapy induced neither neuroinflammation nor T cell responses to Abeta peptide in both APP23 and wild-type B6 mice, even after long-term vaccination. Although it is reported that other anti-Abeta therapies have pharmacological and/or technical difficulties, nonviral DNA vaccines are highly secure and easily controllable and are promising for the treatment of Alzheimer's disease.