Neuromyelitis optica (NMO) is an autoimmune astrocytopathy mediated by anti-AQP4 antibody-producing B cells. Recently, a B-cell subset highly expressing CD11c and T-bet, originally identified as age-associated B cells, has been shown to be involved in the pathogenesis of various autoimmune diseases. The objective of this study was to determine the relationship between the frequency of CD11c^high B cells per CD19⁺ B cells in the peripheral blood of patients with NMO and the clinical profiles including the brain volume. In this observational study, 45 patients with anti-AQP4 antibody-positive NMO in remission and 30 healthy control subjects (HCs) were enrolled. Freshly isolated peripheral blood mononuclear cells were analyzed for immune cell phenotypes. The frequency of CD11c^high B cells per CD19⁺ B cells was assessed by flow cytometry and was evaluated in association with the clinical profiles of patients. Brain MRI data from 26 patients were included in the study for the analysis on the correlation between CD11c^high B-cell frequency and brain atrophy. We found that the frequency of CD11c^high B cells in CD19⁺ B cells was significantly increased in patients with NMO compared with HCs. The expansion of CD11c^high B cells significantly correlated with EDSS, past relapse numbers, and disease duration. In addition, a higher frequency of CD11c^high B cells negatively correlated with total brain, white matter, and gray matter volumes and positively correlated with T2/FLAIR high lesion volumes. When the past clinical relapse episodes of patients with or without the expansion of CD11c^high B cells were compared, relapses in the brain occurred more frequently in patients with CD11c^high B-cell expansion. CD11c^high B cells had distinct features including expression of chemokine receptors associated with migration into peripheral inflammatory tissues and antigen presentation. CD11c^high B-cell frequency was positively correlated with T peripheral helper-1 (Tph-1) cell frequency. Even during the relapse-free period, CD11c^high B cells could expand in the long disease context, possibly through the interaction with Tph-1 cells. The increased frequency of CD11c^high B cells associated with brain atrophy and disease severity, indicating that this cell population could be involved in chronic neuroinflammation in NMO.

Background: Multiple sclerosis (MS) is an autoimmune inflammatory disease of the central nervous system that causes the damage to the myelin sheath as well as axonal degeneration. Individuals with MS appear to have changes in the numbers and functions of T-cell subsets, leading to an immunological imbalance accompanied by enhanced autoreactivity. In previous preclinical studies, (2 S,3 S,4R)-1-O-(α-D-Galactopyranosyl)-N-tetracosanoyl-2-amino-1,3,4-nonanetriol (OCH), a synthetic analog of α-galactosylceramide stimulatory for invariant NKT (iNKT) cells, has shown therapeutic or disease-preventive immunoregulatory effects in autoimmune disease models such as experimental autoimmune encephalomyelitis (EAE). Objectives: This study is the first-in-human study of oral OCH to evaluate the pharmacokinetics and to examine the effects on immune cells as well as related gene expression profiles. Methods: Fifteen healthy volunteers and 13 MS patients who met the study criteria were enrolled. They were divided into five cohorts and received oral administration of various doses of granulated powder of OCH (0.3–30 mg), once per week for 4 or 13 weeks. Plasma OCH concentrations were measured by high-performance liquid chromatography. Frequencies of lymphocyte subsets in peripheral blood were evaluated by flow cytometry, and microarray analysis was performed to determine OCH-induced changes in gene expression. Results: Oral OCH was well tolerated, and its bioavailability was found to be sufficient. Six hours after a single dose of OCH, increased frequencies of Foxp3⁺ regulatory T-cells were observed in some cohorts of healthy subjects and MS patients. Furthermore, gene expression analysis demonstrated an upregulation of several immunoregulatory genes and downregulation of pro-inflammatory genes following OCH administration. Conclusion: This study has demonstrated immunomodulatory effects of the iNKT cell-stimulatory drug OCH in human. Safety profiles together with the presumed anti-inflammatory effects of oral OCH encouraged us to conduct a phase II trial.

Early cognitive impairment (CI) detection is crucial in multiple sclerosis (MS). However, it can progress silently regardless of relapse activity and reach an advanced stage. We aimed to determine whether the corpus callosum area (CCA) is a sensitive and feasible marker for CI in MS compared to other neuroimaging markers. We assessed cognitive function in 77 MS patients using the Symbol Digit Modalities Test, Paced Auditory Serial Additions Task, Wechsler Adult Intelligence Scale-IV, and Wechsler Memory Scale-Revised. The neuroimaging markers included manually measured CCA, two diffusion tensor imaging markers, and nine volumetric measurements. Apart from volumes of the hippocampus and cerebellum, ten markers showed a significant correlation with all neuropsychological tests and significant differences between the groups. The normalized CCA demonstrated a moderate-to-strong correlation with all neuropsychological tests and successfully differentiated between the CI and cognitively normal groups with 80% sensitivity and 83% specificity. The marker had a large area under the curve and a high Youden index (0.82 and 0.63, respectively) and comparability with established cognitive markers. Therefore, the normalized CCA may serve as a reliable marker for CI in MS and can be easily implemented in clinical practice, providing a supportive diagnostic tool for CI in MS.

The significance of anti-contactin-associated protein 1 (Caspr1) antibodies in autoimmune nodopathies (ANs) has not been fully established. The aim of this study was to elucidate the clinical profiles of Caspr1 AN. Consecutive serum samples were included from patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) nationwide who were referred to our laboratory for antibody testing with questionnaires as part of routine clinical practice and who fulfilled definite European Federation of Neurological Societies and Peripheral Nerve Society electrodiagnostic criteria. Anti-Caspr1 immunoglobulin (Ig) G was screened using in-house ELISA and confirmed using immunohistochemistry and Western blotting. Clinical data, electrophysiologic findings, and treatment responses were retrospectively collected. The pathologic features of sural nerves were also examined. Inflammatory Neuropathy Cause and Treatment (INCAT) disability scores, antibody titers, and serum neurofilament light chain (NfL) levels were analyzed at baseline and follow-up. Of 559 screened serum samples from patients with CIDP (median age at onset 54 years, 35% female), 19 cases with anti-Caspr1 IgG were identified; the main subclass was IgG4 (17 cases). Patients with IgG4 Caspr1 AN cases exhibited an older age at disease onset (median 67 years); male predominance (82%); high proportions of limb weakness (100%), gait disturbance (100%), tremor (65%), and sensory ataxia (82%); and very high CSF protein levels (249 mg/dL). Nerve conduction studies showed prolonged F-wave and distal motor latencies and reduced sensorimotor conduction velocities in all nerves tested. Light microscopy findings of sural nerve biopsy specimens from 4 patients with Caspr1 AN indicated a loss of myelinated fiber density and myelin ovoids without macrophage-mediated demyelination or onion bulbs. Electron microscopic evaluation demonstrated axo-glial detachment. Patients with IgG4 Caspr1 AN showed a poor response to IVIg (31%) and needed combined immunotherapies. Even after correcting for age, serum NfL levels were higher in patients with IgG4 Caspr1 AN than in healthy controls (p = 0.0609) and correlated with INCAT scores (p = 0.0143). In the 7 patients with 2 consecutive serum samples, antibody titers decreased with clinical improvement. IgG4 Caspr1 AN presents with a similar clinical phenotype to other nodopathies (e.g., neurofascin 155 and contactin 1), but with an older age at onset. Changes in antibody titers may be a potential biomarker for monitoring disease activity.

Background: Individuals with multiple sclerosis (MS) are vulnerable to all types of infection, because MS itself involves immunodeficiency, in addition to involving treatment with immunosuppressants. Simple predictive variables for infection that are easily assessed in daily examinations are warranted. Lymphocyte area under the curve (L_AUC), defined as the sum of serial absolute lymphocyte counts under the lymphocyte count-time curve, has been established as a predictive factor for several infections after allogenic hematopoietic stem cell transplantation. We assessed whether L_AUC could also be a useful factor for predicting severe infection in MS patients.Methods: From October 2010 to January 2022, MS patients, diagnosed based on the 2017 McDonald criteria, were retrospectively reviewed. We extracted patients with infection requiring hospitalization (IRH) from medical records and matched with controls in a 1:2 ratio. Variables including clinical severity and laboratory data were compared between the infection group and controls. L_AUC was calculated along with the AUC of total white blood cells (W_AUC), neutrophils (N_AUC), lymphocytes (L_AUC), and monocytes (M_AUC). To correct for different times of blood examination and extract mean values of AUC per time point, we divided the AUC by follow-up duration. For example, in evaluating lymphocyte counts, we defined the ratio of [L_AUC] to [follow-up duration] as [L_AUC/t]. Multivariate regression analysis was conducted to extract predictive factors associated with IRH. Also, discriminative analysis was conducted using candidate variables from multivariate analysis.Results: The total case-control sample included 177 patients of MS with IRH (n=59) and non-IRH (controls) (n=118). Adjusted odds ratios (OR) for the risk of serious infection in patients with MS with higher baseline expanded disability status scale (EDSS) (OR 1.340, 95% confidence interval [CI] 1.070–1.670, p = 0.010) and lower ratio of L_AUC/t to M_AUC/t (OR 0.766, 95%CI 0.591–0.993, p = 0.046) were significant. Notably, the kind of treatment, including glucocorticoids (GCs), disease-modifying drugs (DMDs) and other immunosuppressants agents, and dose of GCs were not significantly associated with serious infection after correlated with EDSS and ratio of L_AUC/t to M_AUC/t. In discriminative analysis, sensitivity was 88.1% (95%CI 76.5–94.7%) and specificity was 35.6% (95%CI 27.1–45.0%), using EDSS ≥ 6.0 or ratio of L_AUC/t to M_AUC/t ≤ 3.699, while sensitivity was 55.9% (95%CI 42.5–68.6%) and specificity was 83.9% (95%CI 75.7–89.8%), using both EDSS ≥ 6.0 and ratio of L_AUC/t to M_AUC/t ≤ 3.699.Conclusion: Our study revealed the impact of the ratio L_AUC/t to M_AUC/t as a novel prognostic factor for IRH. Clinicians should pay more attention to laboratory data such as lymphocyte or monocyte counts itself, directly presenting individual immunodeficiency, rather than the kind of drug to prevent infection as a clinical manifestation.