Kazushiro Takata

Neuromyelitis optica: Passive transfer to rats by human immunoglobulin.

Recurrent attacks of optic neuritis and myelitis are the hallmarks of both neuromyelitis optica (NMO) and multiple sclerosis (MS). NMO immunoglobulin G (NMO-IgG), which recognizes astrocytic aquaporin-4 (AQP4) water channels, is a specific serum autoantibody that distinguishes NMO from MS. The pathogenic role of the anti-AQP4 antibody (AQP4-Ab, NMO-IgG) in NMO has been speculated based on several studies in vitro. The aim of this study was to demonstrate the pathogenicity of AQP4-Ab in vivo. We obtained IgG from patients who underwent therapeutic plasmapheresis, and developed an animal model by passive transfer of IgG to rats. The active lesions of the rats exhibited pathological characteristics strikingly similar to those of NMO, marked by astrocytic loss and perivascular deposition of immunoglobulin and complements. These findings provide the first evidence of the pathogenicity of AQP4-Ab in vivo and support the therapeutic efficacy of eliminating the antibodies by plasmapheresis.

Anti-aquaporin-4 antibody induces astrocytic cytotoxicity in the absence of CNS antigen-specific T cells

Neuromyelitis optica (NMO) is an inflammatory demyelinating disease of the central nervous system (CNS). Anti-aquaporin-4 antibody (AQP4-Ab) is a highly specific serum autoantibody that is detected in patients with NMO. Several lines of evidence indicate that AQP4-Ab not only serves as a disease marker but also plays a pivotal role in the pathogenesis of NMO. Although the pathogenicity of AQP4-Ab in vivo has recently been demonstrated, the presence of CNS antigen-specific T cells is recognized as a prerequisite for the antibody to exert pathogenic effects. Thus, it remains unclear whether AQP4-Ab is the primary cause of the disease or a disease-modifying factor in NMO. Here we report that pre-treatment with complete Freunds adjuvant (CFA) alone is sufficient for AQP4-Ab to induce astrocytic damage in vivo. Our results show the primary pathogenic role of AQP4-Ab in the absence of CNS antigen-specific T cells, and suggest that danger signals provided by nonspecific inflammation can be a trigger for those who harbor the autoantibody to develop NMO.

The lactic acid bacterium Pediococcus acidilactici suppresses autoimmune encephalomyelitis by inducing IL-10-producing regulatory T cells.

Background Certain intestinal microflora are thought to regulate the systemic immune response. Lactic acid bacteria are one of the most studied bacteria in terms of their beneficial effects on health and autoimmune diseases; one of which is Multiple sclerosis (MS) which affects the central nervous system. We investigated whether the lactic acid bacterium Pediococcus acidilactici, which comprises human commensal bacteria, has beneficial effects on experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Methodology/Principal Findings P. acidilactici R037 was orally administered to EAE mice to investigate the effects of R037. R037 treatment suppressed clinical EAE severity as prophylaxis and therapy. The antigen-specific production of inflammatory cytokines was inhibited in R037-treated mice. A significant increase in the number of CD4+ Interleukin (IL)-10-producing cells was observed in the mesenteric lymph nodes (MLNs) and spleens isolated from R037-treated naive mice, while no increase was observed in the number of these cells in the lamina propria. Because only a slight increase in the CD4+Foxp3+ cells was observed in MLNs, R037 may primarily induce Foxp3− IL10-producing T regulatory type 1 (Tr1) cells in MLNs, which contribute to the beneficial effect of R037 on EAE. Conclusions/Significance An orally administered single strain of P. acidilactici R037 ameliorates EAE by inducing IL10-producing Tr1 cells. Our findings indicate the therapeutic potential of the oral administration of R037 for treating multiple sclerosis.

Elevation of Sema4A Implicates Th Cell Skewing and the Efficacy of IFN-β Therapy in Multiple Sclerosis

Multiple sclerosis (MS) is a demyelinating autoimmune disease of the CNS and a leading cause of lasting neurologic disabilities in young adults. Although the precise mechanism remains incompletely understood, Ag presentation and subsequent myelin-reactive CD4+ T cell activation/differentiation are essential for the pathogenesis of MS. Although semaphorins were initially identified as axon guidance cues during neural development, several semaphorins are crucially involved in various phases of immune responses. Sema4A is one of the membrane-type class IV semaphorins, which we originally identified from the cDNA library of dendritic cell (DC). Sema4A plays critical roles in T cell activation and Th1 differentiation during the course of experimental autoimmune encephalomyelitis, an animal model of MS; however, its pathological involvement in human MS has not been determined. In this study, we report that Sema4A is increased in the sera of patients with MS. The expression of Sema4A is increased on DCs in MS patients and shed from these cells in a metalloproteinase-dependent manner. DC-derived Sema4A is not only critical for Th1 but also for Th17 cell differentiation, and MS patients with high Sema4A levels exhibit Th17 skewing. Furthermore, patients with high Sema4A levels have more severe disabilities and are unresponsive to IFN-β treatment. Taken together, our results suggest that Sema4A is involved in the pathogenesis of MS by promoting Th17 skewing.

Xanthine Oxidase Mediates Axonal and Myelin Loss in a Murine Model of Multiple Sclerosis

Objectives Oxidative stress plays an important role in the pathogenesis of multiple sclerosis (MS). Though reactive oxygen species (ROS) are produced by various mechanisms, xanthine oxidase (XO) is a major enzyme generating ROS in the context of inflammation. The objectives of this study were to investigate the involvement of XO in the pathogenesis of MS and to develop a potent new therapy for MS based on the inhibition of ROS. Methods XO were assessed in a model of MS: experimental autoimmune encephalomyelitis (EAE). The contribution of XO-generated ROS to the pathogenesis of EAE was assessed by treating EAE mice with a novel XO inhibitor, febuxostat. The efficacy of febuxostat was also examined in in vitro studies. Results We showed for the first time that the expression and the activity of XO were increased dramatically within the central nervous system of EAE mice as compared to naïve mice. Furthermore, prophylactic administration of febuxostat, a XO inhibitor, markedly reduced the clinical signs of EAE. Both in vivo and in vitro studies showed infiltrating macrophages and microglia as the major sources of excess XO production, and febuxostat significantly suppressed ROS generation from these cells. Inflammatory cellular infiltration and glial activation in the spinal cord of EAE mice were inhibited by the treatment with febuxostat. Importantly, therapeutic efficacy was observed not only in mice with relapsing-remitting EAE but also in mice with secondary progressive EAE by preventing axonal loss and demyelination. Conclusion These results highlight the implication of XO in EAE pathogenesis and suggest XO as a target for MS treatment and febuxostat as a promising therapeutic option for MS neuropathology.

Dietary Yeasts Reduce Inflammation in Central Nerve System via Microflora

The intestinal microflora affects the pathogenesis of several autoimmune diseases by influencing immune system function. Some bacteria, such as lactic acid bacteria, have been reported to have beneficial effects on immune function. However, little is known about the effects of yeasts. Here, we aimed to investigate the effects of various dietary yeasts contained in fermented foods on experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), and to elucidate the mechanisms underlying these effects.

Sema4A inhibits the therapeutic effect of IFN-β in EAE.

Approximately one-third of patients with multiple sclerosis (MS) respond poorly to interferon-beta (IFN-β) therapy. Serum Sema4A is increased in MS patients, and those who have high Sema4A do not respond to IFN-β therapy. In this study, we investigated whether recombinant Sema4A abrogates the efficacy of IFN-β in mice with experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Administration of Sema4A concurrently with IFN-β diminished the efficacy of IFN-β in EAE. These effects of Sema4A were attributed to promote Th1 and Th17 differentiation and to increase adhesive activation of T cells to endothelial cells, even in the presence of IFN-β.

11C-Acetate PET Imaging in Patients with Multiple Sclerosis

Background Activation of glial cells is a cardinal feature in multiple sclerosis (MS) pathology, and acetate has been reported to be selectively uptaken by astrocytes in the CNS. The aim of this study was to investigate the efficacy of PET with 11C-acetate for MS diagnosis. Materials and Methods Six patients with relapsing-remitting MS and 6 healthy volunteers (HV) were enrolled. The 11C-acetate brain uptake on PET was measured in patients with MS and HV. Volume-of-interest analysis of cerebral gray and white matter based on the segmentation technique for co-registered MRI and voxel-based statistical parametric analysis were performed. Correlation between 11C-acetate uptake and the lesion number in T1- and T2- weighted MR images were also assessed. Results The standardized uptake value (SUV) of 11C-acetate was increased in both white and gray matter in MS patients compared to HV. Voxel-based statistical analysis revealed a significantly increased SUV relative to that in the bilateral thalami (SUVt) in a broad area of white matter, particularly in the subcortical white matter of MS patients. The numbers of T2 lesions and T1 black holes were significantly correlated with SUV of 11C-acetate in white and gray matter. Conclusions The 11C-acetate uptake significantly increased in MS patients and correlated to the number of MRI lesions. These preliminary data suggest that 11C-acetate PET can be a useful clinical examination for MS patients.

Partial suppression of M1 microglia by Janus kinase 2 inhibitor does not protect against neurodegeneration in animal models of amyotrophic lateral sclerosis

BackgroundAccumulating evidence has shown that the inflammatory process participates in the pathogenesis of amyotrophic lateral sclerosis (ALS), suggesting a therapeutic potential of anti-inflammatory agents. Janus kinase 2 (JAK2), one of the key molecules in inflammation, transduces signals downstream of various inflammatory cytokines, and some Janus kinase inhibitors have already been clinically applied to the treatment of inflammatory diseases. However, the efficacy of JAK2 inhibitors in treatment of ALS remains to be demonstrated. In this study, we examined the role of JAK2 in ALS by administering a selective JAK2 inhibitor, R723, to an animal model of ALS (mSOD1G93A mice).FindingsOrally administered R723 had sufficient access to spinal cord tissue of mSOD1G93A mice and significantly reduced the number of Ly6c positive blood monocytes, as well as the expression levels of IFN- γ and nitric oxide synthase 2, inducible (iNOS) in the spinal cord tissue. R723 treatment did not alter the expression levels of Il-1 β, Il-6, TNF, and NADPH oxidase 2 (NOX2), and suppressed the expression of Retnla, which is one of the markers of neuroprotective M2 microglia. As a result, R723 did not alter disease progression or survival of mSOD1G93A mice.ConclusionsJAK2 inhibitor was not effective against ALS symptoms in mSOD1G93A mice, irrespective of suppression in several inflammatory molecules. Simultaneous suppression of anti-inflammatory microglia with a failure to inhibit critical other inflammatory molecules might explain this result.

Beneficial effects of fingolimod in MS patients with high serum Sema4A levels

We previously demonstrated that patients with multiple sclerosis (MS) of high serum Sema4A levels are resistant to IFN-β therapy. To further elucidate the role of serum Sema4A as a biomarker for therapeutic stratification in MS patients, it is important to clarify the efficacy of other disease-modifying drugs (DMD) in those with high serum Sema4A levels. Thus, in this study we investigated whether fingolimod has beneficial effects on MS patients with high Sema4A levels. We retrospectively analyzed annualized relapse rate (ARR) and Expanded Disability Status Scale (EDSS) change in 56 relapsing—remitting multiple sclerosis (RRMS) patients who had been treated with fingolimod, including those who switched from IFN-β therapy. The levels of Sema4A in the sera were measured by sandwich ELISA. The implications of Sema4A on the efficacy of fingolimod were investigated by administering recombinant Sema4A-Fc and fingolimod to mice with experimental autoimmune encephalomyelitis (EAE). Retrospective analysis of MS cohort (17 high Sema4A and 39 low Sema4A) demonstrated the effectiveness of fingolimod in those with high serum Sema4A levels, showing reduction of ARR (from 1.21 to 0.12) and EDSS progression (from 0.50 to 0.04). Consistent with this observation, improvement in the disease severity of EAE mice receiving recombinant Sema4A-Fc was also observed after fingolimod treatment. These data suggest that fingolimod could serve as a candidate DMD for managing the disease activity of MS patients with high Sema4A levels.