Izumi Kawachi

A mutation in the immunoproteasome subunit PSMB8 causes autoinflammation and lipodystrophy in humans

Proteasomes are multisubunit proteases that play a critical role in maintaining cellular function through the selective degradation of ubiquitinated proteins. When 3 additional β subunits, expression of which is induced by IFN-γ, are substituted for their constitutively expressed counterparts, the structure is converted to an immunoproteasome. However, the underlying roles of immunoproteasomes in human diseases are poorly understood. Using exome analysis, we found a homozygous missense mutation (G197V) in immunoproteasome subunit, β type 8 (PSMB8), which encodes one of the β subunits induced by IFN-γ in patients from 2 consanguineous families. Patients bearing this mutation suffered from autoinflammatory responses that included recurrent fever and nodular erythema together with lipodystrophy. This mutation increased assembly intermediates of immunoproteasomes, resulting in decreased proteasome function and ubiquitin-coupled protein accumulation in the patients tissues. In the patients skin and B cells, IL-6 was highly expressed, and there was reduced expression of PSMB8. Downregulation of PSMB8 inhibited the differentiation of murine and human adipocytes in vitro, and injection of siRNA against Psmb8 in mouse skin reduced adipocyte tissue volume. These findings identify PSMB8 as an essential component and regulator not only of inflammation, but also of adipocyte differentiation, and indicate that immunoproteasomes have pleiotropic functions in maintaining the homeostasis of a variety of cell types.

Cognitive impairment and cortical degeneration in neuromyelitis optica

Neuromyelitis optica spectrum disorder (NMOsd) is an inflammatory and demyelinating syndrome characterized by optic neuritis and myelitis. Several magnetization transfer magnetic resonance imaging (MRI) studies have revealed abnormalities in normal‐appearing gray matter in NMOsd. The aim of this study is to elucidate the characteristics and pathogenesis of cognitive impairment and neurodegeneration in NMOsd brains.

Late-onset anti-NMDA receptor encephalitis.

Objective: To describe the clinical features and outcome of anti–NMDA receptor (NMDAR) encephalitis in patients ≥45 years old. Method: Observational cohort study. Results: In a cohort of 661 patients with anti-NMDAR encephalitis, we identified 31 patients ≥45 years old. Compared with younger adults (18–44 years), older patients were more often male (45% vs 12%, p < 0.0001), had lower frequency of tumors (23% vs 51%, p = 0.002; rarely teratomas), had longer median time to diagnosis (8 vs 4 weeks, p = 0.009) and treatment (7 vs 4 weeks, p = 0.039), and had less favorable outcome (modified Rankin Scale score 0–2 at 2 years, 60% vs 80%, p < 0.026). In multivariable analysis, younger age (odds ratio [OR] 0.15, confidence interval [CI] 0.05–0.39, p = 0.0001), early treatment (OR 0.60, CI 0.47–0.78, p < 0.0001), no need for intensive care (OR 0.09, CI 0.04–0.22, p < 0.0001), and longer follow-up (p < 0.0001) were associated with good outcome. Rituximab and cyclophosphamide were effective when first-line immunotherapies failed (OR 2.93, CI 1.10–7.76, p = 0.031). Overall, 60% of patients older than 45 years had full or substantial recovery at 24 months follow-up. Conclusions: Anti-NMDAR encephalitis is less severe in patients ≥45 years old than in young adults, but the outcome is poorer in older patients. In this age group, delays in diagnosis and treatment are more frequent than in younger patients. The frequency of underlying tumors is low, but if present they are usually carcinomas instead of teratomas in younger patients. Early and aggressive immunotherapy will likely improve the clinical outcome.

Apathy/depression, but not subjective fatigue, is related with cognitive dysfunction in patients with multiple sclerosis

BackgroundCognitive impairment could affect quality of life for patients with multiple sclerosis (MS), and cognitive function may be correlated with several factors such as depression and fatigue. This study aimed to evaluate cognitive function in Japanese patients with MS and the association between cognitive function and apathy, fatigue, and depression.MethodsThe Brief Repeatable Battery of Neuropsychological tests (BRB-N) was performed in 184 Japanese patients with MS and 163 healthy controls matched for age, gender, and education. The Apathy Scale (AS), Fatigue Questionnaire (FQ), and Beck Depression Inventory Second Edition (BDI-II) were used to evaluate apathy, fatigue, and depression, respectively. Student’s t-test was used to compare MS patients and healthy controls. Correlations between two factors were assessed using the Pearson correlation test, and multiple regression analysis was used to evaluate how much each factor affected the BRB-N score.ResultsIn all BRB-N tests, patients with MS scored significantly lower than controls, and the effect size of symbol digit modalities test was the highest among the 9 tests of the BRB-N. Patients with MS had higher AS (p < 0.001), FQ (p < 0.0001), and BDI-II (p < 0.0001) scores than controls. In patients with MS, scores on most of the BRB-N tests correlated with scores on the AS and BDI-II; however, there was little correlation between scores on the BRB-N tests and those on the FQ.ConclusionsCognitive function was impaired, particularly information-processing speed, and decreased cognitive function was correlated with apathy and depression in Japanese patients with MS. Despite the association between cognitive variables and depression/apathy, cognitive function was impaired beyond the effect of depression and apathy. However, subjective fatigue is not related with cognitive impairment. Taken together, this suggests that different therapeutic approaches are needed to improve subjective fatigue and cognition, and thereby quality of life, in patients with MS.

Neurodegeneration in multiple sclerosis and neuromyelitis optica

Multiple sclerosis (MS) and neuromyelitis optica (NMO) are autoimmune demyelinating diseases of the central nervous system (CNS), having distinct immunological and pathological features. They have two pathogenic components, ‘inflammation’ and ‘neurodegeneration’, with different degrees of severity and pathogenetic mechanisms. The target antigen of autoimmunity in NMO is the water channel aquaporin-4 (AQP4), and antibodies directed against this antigen result in astrocyte damage. MS is a disease primarily affecting myelin and oligodendrocytes, but thus far, no MS-specific autoantigen has been identified. The distinct inflammatory processes in these diseases may trigger cascades of events leading to disease-specific neurodegeneration. Damage of the CNS tissue appears to be amplified by mechanisms that are in part shared by the two conditions and involve oxidative burst activation in microglia/macrophages, mitochondrial damage and axonal energy failure, Wallerian degeneration and meningeal inflammation. However, they appear to differ regarding the nature of the inflammatory response, the type and extent of cortical injury, and the type of astrocyte reaction and damage. Here, we provide a detailed comparison of the pathology between MS and NMO, which may help to define shared and disease-specific mechanisms of neurodegeneration in these diseases.

Clinicopathological features in anterior visual pathway in neuromyelitis optica.

Neuromyelitis optica spectrum disorder (NMOsd) is an autoimmune disorder of the central nervous system characterized by aquaporin‐4 (AQP4) autoantibodies. The aim of this study was to elucidate the characteristics of involvement of the anterior visual pathway (AVP) and neurodegeneration via glia–neuron interaction in NMOsd.

Safety and efficacy of thalidomide in patients with POEMS syndrome: a multicentre, randomised, double-blind, placebo-controlled trial

BACKGROUND Polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS) syndrome is a rare cause of demyelinating neuropathy, with multi-organ involvement characterised by plasma cell dyscrasia and VEGF overproduction. No treatments have been established for patients with POEMS syndrome who are not eligible for stem-cell transplantation. Thalidomide suppresses VEGF and plasma cell proliferation. We aimed to assess the safety and efficacy of thalidomide for the treatment of POEMS syndrome. METHODS We did a randomised, double-blind, placebo-controlled, phase 2/3 trial at 12 hospitals in Japan. Adults (age ≥20 years) with POEMS syndrome who were ineligible for autotransplantation were randomly assigned (1:1) by a minimisation method to treatment with oral dexamethasone (12 mg/m(2) per day on the first 4 days of every 28-day cycle) plus either oral thalidomide (200 mg daily) or placebo for six cycles. All study personnel and patients were masked to treatment allocation. The primary endpoint was the reduction rate of serum VEGF concentrations at 24 weeks. Analysis was by intention to treat. This study is registered with the UMIN Clinical Trials Registry, UMIN000004179. FINDINGS Between Nov 11, 2010, and July 3, 2014, we randomly assigned 25 patients to receive either thalidomide (n=13) or placebo (n=12); one patient in the placebo group was excluded from analyses because of a protocol violation. The adjusted mean VEGF concentration reduction rate at 24 weeks was 0·39 (SD 0·34) in the thalidomide group compared with -0·02 (0·54) in the placebo group (adjusted mean difference 0·41, 95% CI 0·02-0·80; p=0·04). Mild sinus bradycardia was more frequent in the thalidomide group than in the placebo group (seven [54%] vs zero; p=0·006). Five patients had serious adverse events: three in the thalidomide group (transient cardiac arrest, heart failure, and dehydration) and two in the placebo group (ileus and fever). No deaths occurred during the randomised study. In the 48-week open-label study period (n=22), newly developed adverse events were sinus bradycardia (n=4), constipation (n=5), and mild sensory neuropathy (n=5). Two patients died in the open-label study; both patients were initially in the placebo group, and the cause of death was progression of the disease. INTERPRETATION Thalidomide reduces serum VEGF concentrations and represents a new treatment for patients with POEMS syndrome who are not eligible for stem-cell transplantation. Thalidomide treatment poses a risk of bradycardia; however, the benefits are likely to exceed the risk. FUNDING Japanese Ministry of Health, Labour, and Welfare, and Fujimoto Pharmaceuticals.

Dendritic cells presenting pyruvate kinase M1/M2 isozyme peptide can induce experimental allergic myositis in BALB/c mice

Polymyositis (PM) is an inflammatory muscle disease caused by autoimmune dysfunction, considered to be caused by cytotoxic CD8 T cells. To date, no autoantigens have been identified. We attempted to induce an experimental allergic myositis (EAM) in BALB/c mice by inoculating syngeneic dendritic cells (DC) presenting peptides that are expected to match the binding anchor motif of H-2K(d) (BALB/c). We selected peptides that are highly expressed in skeletal muscle. Only when we inoculated syngeneic bone marrow-derived DC presenting pyruvate kinase M1/M2 peptide 464-472 in BALB/c mice, 41.7% of the mice (EAM) developed pathological changes in skeletal muscle compatible to human PM. Under other conditions (when we inoculated DC presenting no synthetic peptides into BALB/c or C57BL/6 mice and DC presenting pyruvate kinase M1/M2 peptide into C57BL/6 mice), there were no necrotizing and inflammatory lesions. Induction of EAM in the same manner as above also induced CTL activity against P815 cells with the same peptide and syngeneic differentiated cultured myotubes without peptides by the chromium release assay. Consistent with the similarity of the binding anchor motif of H-2K(d) (BALB/c) and HLA A*2402, we conclude that pyruvate kinase M1/M2 peptide is a candidate autoantigen not only in BALB/c-EAM but also in human-PM with the HLA A*2402 allele.

Efficacy of intravenous methylprednisolone pulse therapy in patients with multiple sclerosis and neuromyelitis optica

Background: No large-scale studies have compared the efficacy of intravenous methylprednisolone pulse therapy (IVMP) for multiple sclerosis (MS) and neuromyelitis optica (NMO). Objective: To explain differences in treatment responses of MS and NMO patients to IVMP. Methods: Changes in neurological symptoms/signs and Expanded Disability Status Scale (EDSS) scores before and within 1 week of IVMP completion were obtained in 2010 at 28 institutions, and retrospectively collated from 271 MS (478 courses) and 73 NMO (118 courses) cases. Results: In MS patients, decreased EDSS score was significant after the first (−0.8 ± 0.9), second (−0.7 ± 0.9), and third (−0.7 ± 0.8) courses (p < 0.05), but not after the fourth (−0.3 ± 0.7) and fifth (−0.5 ± 0.6). However, decreased EDSS score was only significant after the first course (−0.5 ± 1.5, p < 0.05) in NMO patients. EDSS score was significantly decreased in MS compared with NMO patients at the first course (p < 0.05), but not thereafter. Model analysis for EDSS score improvement at the first course, adjusting for covariates, showed significantly greater decreases in MS compared with NMO patients (p < 0.05). Conclusion: IVMP is effective in MS from the first to third courses, and in NMO at the first course. Additionally, IVMP is more efficacious in MS than NMO patients, even at the first course.

Relapse of multiple sclerosis in a patient retaining CCR7-expressing T cells in CSF under fingolimod therapy

Fingolimod acts as a functional antagonist of the sphingosine-1-phosphate receptor, and it traps lymphocytes in secondary lymphoid organs and precludes their migration into the central nervous system. We report the case of a patient who suffered a relatively severe relapse of multiple sclerosis (MS) during the initial 3 months of fingolimod therapy, with retention of CCR7 expression on CD4+ T cells in the cerebrospinal fluid (CSF) despite decreased numbers of lymphocytes and decreased expression of CCR7 on CD4+ T cells in the blood. These data suggest that fingolimod may cause differential effects on the CSF and blood lymphocytes of patients with MS during the initial months of therapy.