Neuromyelitis optica (NMO) is an acute inflammatory demyelinating disease of the CNS. The presence of astrocyte-targeted AQP4-immunoglobulin G (IgG) in peripheral blood is a major factor in its diagnosis. Previous studies show that AQP4-IgG contributes directly to CNS inflammation and that B cells play a central pathogenic role in NMO. However, where and how the B-cell response is altered remains controversial. In this study, we used high-parameter flow cytometry to carry out a comprehensive analysis of the immune cell populations in the CSF samples obtained from first-episode acute-phase NMO patients, compared with those from patients with acute-phase multiple sclerosis and other neurological diseases. Among 10 immune cell populations defined in the analysis, the frequency only of B cells and antibody-secreting cells (ASC) was higher in the CSF of acute-phase NMO compared with other neurological diseases. Detailed assessments of B-cell and ASC subsets in the CSF revealed differences in the dominant subsets between NMO and multiple sclerosis. In NMO, a series of CD21lo B-cell subsets, including 'activated' naïve B, double-negative and switched memory subsets, considered as ASC precursors, were dominant. A majority of these CD21lo B-cell subsets expressed CD69 and CXCR3, suggesting their CNS residency. An increase of CD21lo B-cell subsets was also observed in the CSF of treatment-refractory NMO patients. Furthermore, two B-helper T-cell subsets, T peripheral helper type 1 and T follicular helper type 1 cells, both highly expressing CD69 and CXCR3, were enriched in the CSF of NMO patients, suggesting their interactions with ASC precursors in the CNS. In vitro culture experiments using blood samples from patients with NMO showed that CD21lo B cells included AQP4-IgG-producing cells and displayed a high propensity to differentiate into ASCs. We also found that CD21lo B-cell subsets in NMO upregulated the expression of C5a receptors, and C5a signals promoted their differentiation into ASCs. ASCs derived from CD21lo B cells expressed high levels of CXCR3 and CD138. The increase in CD21lo B-cell subsets was significantly correlated with the annual relapse rate. Collectively, our study strongly suggests that the mechanism to promote the generation of CD21lo B cells, probably via the extrafollicular pathway, becomes activated during the acute phase of NMO and that the generated CD21lo B-cell subsets contribute to the pathogenesis. Targeting CD21lo B-cell subsets might be useful for the development of novel therapeutic approaches.

'No evidence of disease activity (NEDA)', judged by clinical and radiological findings, is a therapeutic goal in patients with multiple sclerosis (MS). It is, however, unclear if distinct biological mechanisms contribute to the maintenance of NEDA. To clarify the immunological background of long-term disease stability defined by NEDA, circulating immune cell subsets in patients with relapsing-remitting MS (RRMS) were analyzed using flow cytometry. Patients showing long-term NEDA (n = 31) had significantly higher frequencies of non-classical monocytes (NCMs) (6.1% vs 1.4%) and activated regulatory T cells (Tregs; 2.1% vs 1.6%) than those with evidence of disease activity (n = 8). The NCM frequency and NCMs to classical monocytes ratio (NCM/CM) positively correlated with activated Treg frequency and duration of NEDA. Co-culture assays demonstrated that NCMs could increase the frequency of activated Tregs and the expression of PD-L1, contributing to development of Tregs, was particularly high in NCMs from patients with NEDA. Collectively, NCMs contribute to stable remission in patients with RRMS, possibly by increasing activated Treg frequency. In addition, the NCM frequency and NCM/CM ratio had high predictive values for disease stability (AUC = 0.97 and 0.94, respectively), suggesting these markers are potential predictors of a long-term NEDA status in RRMS.

>The immune system has been attracting increasing attention in the field of chronic neurological disorders in the central nervous system(CNS).Autoreactive T cells targeting CNS antigens play a crucial role in the development of various autoimmune diseases,such as multiple sclerosis(MS) and neuromyelitis optica spectrum disorder(NMOSD).Moreover,T cells are now recognized as a pivotal contributor to the pathology of neurodegenerative disorders,including Alzheimer's disease(AD),Parkinson's disease(PD),and multiple system atrophy.

Background and Objectives Resident memory T (Trm) cells are a unique population that can survive and function in a compartmentalized tissue with inflammatory potential. We aim to investigate the alteration of Trm population in acute/chronic inflammatory and neurodegenerative diseases in the CNS. Methods The frequencies of CD4+ and CD8+ T cells expressing both CD69 and CD103, the markers for Trm cells, were quantified in the peripheral blood and CSF (n = 80 and 44, respectively) in a cross-sectional manner. The transcriptional profile of Trm-like population in the CSF was further analyzed using a public single-cell dataset. Results The frequency of CD69+CD103+CD8+ T cells was strikingly higher in the CSF than in the peripheral blood (among memory fraction, 13.5% vs 0.11%, difference (mean [SE]): 13.4% [2.9]). This CD69+CD103+CD8+ T-cell population was increased in the CSF from patients with chronic inflammatory diseases including multiple sclerosis and with neurodegenerative diseases such as Parkinson disease and Alzheimer disease compared with controls (11.5%, 13.0%, 8.1% vs 2.9%, respectively). By contrast, the frequency was not altered in acute inflammatory conditions in the CNS (4.0%). Single-cell RNAseq analysis confirmed Trm signature in CD69+CD103+CD8+ T cells in the CSF, supporting their Trm-like phenotype, which was not clear in controls. Discussion Collectively, an increase in CD69+CD103+CD8+ Trm-like population in the CSF is related with both chronic neuroinflammatory and some neurodegenerative diseases in the CNS, suggesting a partially shared pathology in these diseases.

Purpose:To evaluate the use of delay alternating with nutation for tailored excitation-prepared T1-weighted turbo spin echo (DANTE T1-SPACE) imaging for diagnosing optic neuritis and to analyze its correlation with clinical findings before and after treatment. Patients and Methods:Patients diagnosed with optic neuritis or non-arteritic anterior ischemic optic neuropathy (NA-AION) were evaluated at the Ophthalmology Department of Kyoto University Hospital. All patients underwent magnetic resonance (MR) studies before treatment initiation and ophthalmic examinations before and after treatment. Three ophthalmologists independently reviewed the MR scans for abnormalities. The magnetic resonance imaging (MRI) assessments included post-contrast DANTE T1-SPACE, post-contrast volumetric interpolated breath-hold examination (VIBE), and short T1 inversion recovery (STIR) scans. The presence of abnormalities in each sequence was determined. Results:Of 36 eyes from 30 patients, 21 eyes from 17 patients were diagnosed with optic neuritis, and 15 eyes from 13 patients were diagnosed with NA-AION. DANTE T1-SPACE sequences showed better sensitivity for detecting optic neuritis than STIR sequences (100% vs 67%, p = 0.009). VIBE images did not confirm enhancement of lesions in some cases with optic neuritis. No differences were observed among the sequences for NA-AION. Lesion length evaluated by DANTE T1-SPACE sequences was associated with circumpapillary retinal nerve fiber layer thickness at the initial visit, eye pain, and the time interval from symptom onset to MRI scan. Conclusion:Contrast-enhanced DANTE T1-SPACE was better than other sequences of MRI for diagnosing optic neuritis.

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). Its early phase is characterized by a relapse-remitting disease course, followed by disability progression in the later stage. While chronic inflammation accompanied with degeneration is well-established as the key pathological feature, the pathogenesis of MS, particularly progressive MS, remains elusive. Sulfatide is a major glycolipid component of myelin, and previous studies in experimental autoimmune encephalomyelitis mouse models have demonstrated it to have immune-protective functions. Notably, sulfatide concentration is increased in the serum and cerebrospinal fluid of patients with MS, particularly those in a progressive disease course. Here, we show that the myelin-glycolipid sulfatide displays an ability to suppress the proliferation of polyclonally activated human T cells. Importantly, this suppressive effect was impaired in T cells obtained from MS patients having higher disability status. Therefore, it is plausible that progression of MS is associated with an escape from the immune-regulatory effect of sulfatide. Our study suggests that, although the precise mechanisms remain unrevealed, an escape of T cells from immunosuppression by sulfatide is associated with disease progression in the advanced stage. Further studies will provide novel insights into the pathogenesis of MS, particularly regarding disease progression, and help develop novel treatment strategies for this challenging disease.

Objective To clarify functional alterations of follicular helper T cells (Tfh) in myasthenia gravis (MG) because Tfh play important roles in helping B cells generate antibody-producing cells. Methods A total of 24 immunotherapy-naive patients with anti–acetylcholine receptor (AchR) antibody–positive MG and 18 age-matched healthy subjects (HS) were enrolled. Samples from 6 patients were available for posttreatment analysis. Subsets of circulating Tfh (cTfh) and B cells were identified by flow cytometry analysis of surface molecules. Cytokine production by isolated cTfh subsets from 5 patients with MG and 5 HS was measured in vitro. Analysis was performed to examine the correlation between the frequency of cTfh subsets and that of plasmablasts and between cTfh subsets and the quantitative MG score. Results cTfh increased with elevated expression of inducible T-cell costimulator (ICOS) in patients with MG. cTfh shifted to Th2 and Th17 over Th1 in MG. ICOShighcTfh produced significantly higher levels of interleukin (IL)-21, IL-4, and IL-17A than ICOSlow cTfh only in patients with MG. The frequency of cTfh within CD4 T cells was more closely associated with disease severity than the serum anti-AchR antibody titer and frequency of plasmablasts within B cells. Abnormalities of cTfh were improved after immunotherapy in parallel with clinical improvement. Conclusions Alternation of cTfh is a key feature in the development of MG and may become a biomarker for disease severity and therapeutic efficacy. Classification of Evidence This study provides Class II evidence that the level of cTfh is associated with disease severity in patients with MG.

OBJECTIVE:Although plasmapheresis is a treatment option for patients with autoimmune neurological diseases, treatment response varies greatly among patients. The main objective of this study was to find out if biological/immune traits correlate with a beneficial response.METHODS:We thoroughly analyzed immune phenotypes in paired blood samples from a cohort of 31 patients with multiple sclerosis before and after plasmapheresis, in parallel with clinical evaluation of treatment response.RESULTS:The frequency of IFN-γ+ Th1 cells was persistently higher in those who obtained benefit from plasmapheresis (responders) than nonresponders. The Th1 cell frequency before plasmapheresis provided a high predictive value for beneficial response, achieving area under the curve (AUC) of 0.902. Plasmapheresis treatment decreased inflammation-related gene expressions in Th1 cells. Meanwhile, IFNG expression in Th1 cells positively correlated with the frequency of CD11c+ B cells, of which a pathogenic role has been suggested in several autoimmune diseases. In line with this, in vitro experiments showed that CD11c+ B cells would increase in response to exogenous IFN-γ compared to IL-4, and secrete high amounts of IgG. B cell receptor analysis indicated that clonal expansion of CD11c+ B cells takes place in patients with multiple sclerosis. Interestingly, CD11c+ B cells, which showed unique gene expression profile, decreased after plasmapheresis treatment along with all the immunoglobulin subsets in the circulation.INTERPRETATION:Taken together, we postulate that Th1 cell - CD11c+ B cell axis is involved in treatment response to plasmapheresis, giving us clues to better understanding of complicated pathogenesis of autoimmune diseases, and getting closer to a personalized therapy. ANN NEUROL 2021;90:595-611.

Regulatory T (Treg) cells are known to suppress excessive inflammation in autoimmune diseases, including multiple sclerosis (MS). Accumulating evidence suggests that the frequency and suppressive function of Treg cells are altered in patients with MS, which might be involved in the development and exacerbation of the disease. In addition, there are several Treg cell populations with distinct functions, which are differently affected by MS. The importance of these observations is supported by studies using an animal disease model, experimental autoimmune encephalomyelitis. The environmental factors are also discussed that might underlie the alteration of Treg cells in MS. The perturbation of Treg cell homeostasis could be restored by some disease-modifying drugs. The beneficial effects of these drugs might be partially mediated by Treg cells. Understanding the dynamics of this population is crucial to reveal the pathogenesis and to develop more effective treatment strategies in MS.

Neuromyelitis optica spectrum disorder (NMOSD) has a wide disease spectrum and sometimes shows abnormal eye movement with brainstem manifestations. However, bilateral oculomotor nerve palsy with a midbrain lesion has never been reported in a patient with NMOSD. We describe a 61-year-old woman with progressive ptosis and diplopia. She displayed bilateral oculomotor nerve palsy and hypersomnia. Brain MRI demonstrated abnormal signal intensities in the midbrain and around the third ventricle and hypothalamus with a mild contrast enhancement. A cerebrospinal fluid study indicated elevated protein and pleocytosis. Because serum anti-aquaporin-4 IgG antibody was positive, the patient was diagnosed with neuromyelitis optica spectrum disorder with aquaporin-4 IgG. We report for the first time bilateral oculomotor nerve palsy as an initial manifestation in a patient with aquaporin-4 positive NMOSD.

Dear Editor,Acute intracerebral hemorrhage (ICH) is rarely complicated by concomitant cerebral infarction.Some studies have reported observing new ischemic lesions together with ICH, but mainly as subclinical lesions located in different vascular territories [1,2].However, to the best of our knowledge, symptomatic perforating artery infarction adjacent to an ICH has not been reported previously.We present herein the first descriptions of delayed perforating artery infarction adjacent to hematoma and discuss the possible pathophysiologic mechanisms.

Myasthenia gravis (MG) is occasionally associated with autoimmune diseases in the central nervous system (CNS), such as neuromyelitis optica spectrum disorder (NMOSD), multiple sclerosis (MS), Morvan syndrome, and anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. Here, we report five original cases associated with autoimmune disorders in the CNS among 42 patients with MG in a single tertiary hospital in Japan (11.9%). In four of these five cases, the second disease developed when the preceding disease was unstable. Accurate diagnosis of the newly developing disease may be difficult in such cases, because some neurological symptoms can be seen in both disorders. This implies the great importance of recognizing the possible co-occurrence of MG and disorders in the CNS. In addition, a comprehensive review of the literature revealed distinct clinical characteristics depending on the associated disease in the CNS, including thymic pathology and temporal relationship between MG and associated CNS disorders. Notably, NMOSD usually develops after the onset of MG and thymectomy, in clear contrast to MS. Thymoma is highly prevalent among patients with Morvan syndrome, in contract to cases with NMOSD and MS. The analysis of clinical characteristics, representing the first such investigation to the best of our knowledge, suggests different pathogeneses of these autoimmune diseases in the CNS, and provides significant implications for clinical practice.

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system, in which myelin and oligodendrocytes are the main targets recognized by inflammatory CD4+ T cells reactive to myelin peptides. Regulatory CD4+ T (Treg) cells normally keep homeostasis of the immune system by inhibiting detrimental effects of inflammatory T cells. However, Treg cells are reduced in patients with MS for unknown reason. This commentary highlights a novel function of circulating exosomes to inhibit the differentiation of Treg cells in MS. Our recent work has demonstrated that the circulating exosomes, a member of extracellular vesicles, of patients with MS exert this effect by transferring let-7i to naive CD4+ T cells. The transferred let-7i subsequently causes a decreased expression of insulin like growth factor 1 receptor (IGF1R) and transforming growth factor β receptor 1 (TGFBR1), leading to the inhibition of Treg cell differentiation. Thus, extrinsic microRNAs transferred by exosomes might have an active role in triggering autoimmune diseases. We hypothesize that extracellular vesicles including exosomes can be a communication tool between the gut microbiota and the host immune system. Further research in this area will expand the knowledge about the precise mechanism of autoimmune diseases and can lead to a new therapeutic approach.

Circulating exosomes are involved in the pathogenesis of MS by suppressing the induction of Treg cells via let-7i-IGF1R/TGFBR1 pathway. None declared.

コイル塞栓術後に, 遅発性に神経症状を呈する合併症の報告がされている. 症例は70歳女性, 右内頚動脈後交通動脈分岐部脳動脈瘤の破裂によるくも膜下出血に対してコイル塞栓術を行い, 発症4週間後に神経症状なく退院した. しかし退院1カ月後から左不全麻痺が出現し, magnetic resonance imagingにて浮腫を伴う多発性結節性の造影病変を認め, 再入院となった. ステロイドパルス療法を開始し症状, 画像所見ともに改善した. 過去の文献報告から親水コーティングが剝離し, コーティングにより脳実質に浮腫を伴う肉芽腫が形成され, 症状を呈したと推測された. 血管内治療の適応が増加している中で, 注意すべき合併症であると思われる.

Background: Exosomes are extracellular vesicles which are involved in intercellular communications by delivering a variety of molecules such as miRNAs, though the pathogenic function of exosomes has not been studied in multiple sclerosis (MS). It has been indicated that regulatory T (Treg) cells are reduced in MS, of which underlying mechanism is still unknown.

Multiple sclerosis (MS) is a T cell-mediated autoimmune disease of the central nervous system. Foxp3 + regulatory T (Treg) cells are reduced in frequency and dysfunctional in patients with MS, but the underlying mechanisms of this deficiency are unclear. Here, we show that induction of human IFN-γ − IL-17A − Foxp3 + CD4 + T cells is inhibited in the presence of circulating exosomes from patients with MS. The exosomal miRNA profile of patients with MS differs from that of healthy controls, and let-7i , which is markedly increased in patients with MS, suppresses induction of Treg cells by targeting insulin like growth factor 1 receptor ( IGF1R ) and transforming growth factor beta receptor 1 ( TGFBR1 ). Consistently, the expression of IGF1R and TGFBR1 on circulating naive CD4 + T cells is reduced in patients with MS. Thus, our study shows that exosomal let-7i regulates MS pathogenesis by blocking the IGF1R/TGFBR1 pathway.

Objective: To compare effects of natalizumab on inflammatory and regulatory T cells with regard to expression of α4-integrin (CD49d). Methods: Twenty-seven natalizumab-naive and 8 natalizumab-treated patients with multiple sclerosis (MS), 7 patients with neuromyelitis optica (NMO) or NMO spectrum disorder, and 8 healthy controls were included. The positive rate of CD49d was analyzed and compared among T helper 1 (Th1), T helper 17 (Th17), and regulatory T (Treg) cells (CD49d+Th1, CD49d+Th17, and CD49d+Treg, respectively). Results: Natalizumab treatment increased CD49d ratios, CD49d+Th1/CD49d+Treg, and CD49d+Th17/CD49d+Treg. This indicates larger reduction of the CD49d+ population in Treg cells than in Th1 or Th17 cells. The CD49d ratios of 2 patients who experienced exacerbation during natalizumab treatment were remarkably higher than those of the other natalizumab-treated patients. Natalizumab treatment increased the expression of TBX21, RORC, interferon (IFN)–γ, and interleukin (IL)–17A, and decreased the expression of FOXP3 in CD49d+ memory CD4 T cells. Natalizumab treatment also increased the amount of IFN-γ and IL-17A secreted by CD49d+ memory CD4 T cells. Conclusions: The reduction rate of the CD49d+ population in Treg cells was larger than that in Th1 or Th17 cells. Although the large reduction in CD49d+ population is beneficial for MS, the proinflammatory state of residual CD49d+ cells might, in part, explain the presence of disease activity under natalizumab treatment.

Background: Fingolimod is highly effective in preventing multiple sclerosis (MS) relapses. However, relapses can occur in fingolimod-treated patients by unknown mechanisms. Objectives: To study several features of circulating T cells under fingolimod treatment.