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Background and Objectives: Biologics that target pathogenic antibodies (Abs) and their effector functions such as the complement inhibitor ravulizumab and the neonatal Fc receptor agonist efgartigimod have recently been approved for the treatment of acetylcholine receptor (AChR)-Ab-positive myasthenia gravis (MG), but comparative studies are lacking., Methods: In a prospective, exploratory real-world study, we assessed clinical efficacy, safety, and biological effects of ravulizumab and efgartigimod treatment initiation. Myasthenia Gravis-Activities of Daily Living and Quantitative Myasthenia Gravis scores were used as clinical endpoints. Ab effector functions were determined by AChR-Ab-dependent complement activation and phagocytosis assays and systemic complement activation profiling., Results: We observed similar moderate short-term efficacy of ravulizumab and efgartigimod in achieving clinical improvement. Ravulizumab reduced systemic terminal complement activation, but neither treatment showed significant effects on complement pathways proximal to C5 or functional capacities of AChR-Abs. Both treatment modalities were well tolerated with no serious adverse events reported., Discussion: Clinical benefits obtained with ravulizumab and efgartigimod can be remarkably heterogeneous in daily clinical practice. Neither treatment relevantly changed effector functions of pathogenic AChR-Abs, supporting the concept that durable disease control in MG requires continuous administration of both fast-acting agents., Classification of Evidence: This study provides Class III evidence that in AChR-Ab-positive patients with generalized MG, ravulizumab and efgartigimod provide comparable modest improvement in MG functional scales.

Background: Neuronal nicotinic acetylcholine receptors (nAChRs) are abundant in the central nervous system (CNS), playing critical roles in brain function. Antigenicity of nAChRs has been well demonstrated with antibodies to ganglionic AChR subtypes (i.e., subunit α3 of α3β4-nAChR) and muscle AChR autoantibodies, thus making nAChRs candidate autoantigens in autoimmune CNS disorders. Antibodies to several membrane receptors, like NMDAR, have been identified in autoimmune encephalitis syndromes (AES), but many AES patients have yet to be unidentified for autoantibodies. This study aimed to develop of a cell-based assay (CBA) that selectively detects potentially pathogenic antibodies to subunits of the major nAChR subtypes (α4β2- and α7-nAChRs) and its use for the identification of such antibodies in "orphan" AES cases., Methods: The study involved screening of sera derived from 1752 patients from Greece, Turkey and Italy, who requested testing for AES-associated antibodies, and from 1203 "control" patients with other neuropsychiatric diseases, from the same countries or from Germany. A sensitive live-CBA with α4β2-or α7-nAChR-transfected cells was developed to detect antibodies against extracellular domains of nAChR major subunits. Flow cytometry (FACS) was performed to confirm the CBA findings and indirect immunohistochemistry (IHC) to investigate serum autoantibodies' binding to rat brain tissue., Results: Three patients were found to be positive for serum antibodies against nAChR α4 subunit by CBA and the presence of the specific antibodies was quantitatively confirmed by FACS. We detected specific binding of patient-derived serum anti-nAChR α4 subunit antibodies to rat cerebellum and hippocampus tissue. No serum antibodies bound to the α7-nAChR-transfected or control-transfected cells, and no control serum antibodies bound to the transfected cells. All patients positive for serum anti-nAChRs α4 subunit antibodies were negative for other AES-associated antibodies. All three of the anti-nAChR α4 subunit serum antibody-positive patients fall into the AES spectrum, with one having Rasmussen encephalitis, another autoimmune meningoencephalomyelitis and another being diagnosed with possible autoimmune encephalitis., Conclusion: This study lends credence to the hypothesis that the major nAChR subunits are autoimmune targets in some cases of AES and establishes a sensitive live-CBA for the identification of such patients., Competing Interests: Authors MP, KK, EK, AT, MD, EN and ST were employed by company Tzartos NeuroDiagnostics. ST has shares in the research and diagnostic laboratory Tzartos NeuroDiagnostics. ST and JT have filed a patent on a cell-based method for detecting potentially pathogenic autoantibodies to neuronal nAChRs. RM received funding for travel, meeting attendance or Advisory Board participation from Alexion, Argenx, Biomarin, Catalyst, SANOFI, Regeneron and UCB. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Pechlivanidou, Vakrakou, Karagiorgou, Tüzün, Karachaliou, Chroni, Afrantou, Grigoriadis, Argyropoulou, Paschalidis, Şanlı, Tsantila, Dandoulaki, Ninou, Zisimopoulou, Mantegazza, Andreetta, Dudeck, Steiner, Lindstrom, Tzanetakos, Voumvourakis, Giannopoulos, Tsivgoulis, Tzartos and Tzartos.)

Background/aim: The presence of a monoclonal gammopathy of undetermined significance (MGUS) even in small amounts may trigger tissue damage through immunological or other mechanisms, irrespective of the potential for malignant transformation. The aim of the study was to present a case of monoclonal gammopathy of clinical significance with ocular manifestations and discuss relevant literature., Case Report: In our case, a patient presented with vision disturbances that was eventually attributed to the underlying IgM MGUS after extensive workup to exclude other potential etiologies. The patient showed a clinical response with the fixed-duration DRC (dexamethasone, rituximab, cyclophosphamide) regimen that persisted for at least 1.5 years. Herein, we present, in detail, the patient management and discuss the underlying pathophysiology of this rare entity with few available published data in this field., Conclusion: A high level of clinical suspicion is necessary in order to detect the association between MGUS and a clinical sign or symptom that cannot be attributed elsewhere., (Copyright © 2024, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background/aim: Kelch-like protein 11 (KLHL11)-antibody may be found in paraneoplastic neurological disorders presenting with epileptic seizures. The aim of this study was to investigate the prevalence and clinical significance of KLHL11-antibody in epilepsy., Patients and Methods: Sera of 42 pediatric and 59 adult patients with seizures of undetermined cause were screened using a cell-based assay., Results: KLHL11-antibody was found in three of 168 control patients with paraneoplastic neurological disorders and four pediatric patients (4-8-year-old, 2 boys/2 girls) with seizures of unknown cause presenting with myoclonic-atonic epilepsy, generalized epilepsy or childhood epilepsy with centrotemporal spikes. In these four cases, seizures continued for 2-7 months, responded promptly and favorably to conventional anti-seizure drugs and did not recur in follow-up durations ranging between 2-5 years. Patients had normal brain MRI findings and motor-mental development before and after seizures. KLHL11-antibody was not detected in adult epilepsy patients with undetermined cause, MOG antibody-positive patients and healthy controls., Conclusion: KLHL11-antibody may be detected in pediatric epilepsy patients with a relatively benign disease course., (Copyright © 2024, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Introduction: Autoimmune disorders (ADs) are a group of about 80 disorders that occur when self-attacking autoantibodies are produced due to failure in the self-tolerance mechanisms. ADs are polygenic disorders and associations with genes both in the human leukocyte antigen (HLA) region and outside of it have been described. Previous studies have shown that they are highly comorbid with shared genetic risk factors, while epidemiological studies revealed associations between various lifestyle and health-related phenotypes and ADs., Methods: Here, for the first time, we performed a comparative polygenic risk score (PRS) - Phenome Wide Association Study (PheWAS) for 11 different ADs (Juvenile Idiopathic Arthritis, Primary Sclerosing Cholangitis, Celiac Disease, Multiple Sclerosis, Rheumatoid Arthritis, Psoriasis, Myasthenia Gravis, Type 1 Diabetes, Systemic Lupus Erythematosus, Vitiligo Late Onset, Vitiligo Early Onset) and 3,254 phenotypes available in the UK Biobank that include a wide range of socio-demographic, lifestyle and health-related outcomes. Additionally, we investigated the genetic relationships of the studied ADs, calculating their genetic correlation and conducting cross-disorder GWAS meta-analyses for the observed AD clusters., Results: In total, we identified 508 phenotypes significantly associated with at least one AD PRS. 272 phenotypes were significantly associated after excluding variants in the HLA region from the PRS estimation. Through genetic correlation and genetic factor analyses, we identified four genetic factors that run across studied ADs. Cross-trait meta-analyses within each factor revealed pleiotropic genome-wide significant loci., Discussion: Overall, our study confirms the association of different factors with genetic susceptibility for ADs and reveals novel observations that need to be further explored., Competing Interests: KP is Founder and Head of the Institute for Research and Innovation. Based at Patras Science Park. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Topaloudi, Jain, Martinez, Bryant, Reynolds, Zagoriti, Lagoumintzis, Zamba-Papanicolaou, Tzartos, Poulas, Kleopa, Tzartos, Georgitsi, Drineas and Paschou.)

Aquaporins (AQPs; AQP0-AQP12) are water channels expressed in many and diverse cell types, participating in various functions of cells, tissues, and systems, including the central nervous system (CNS). AQP dysfunction and autoimmunity to AQPs are implicated in several diseases. The best-known example of autoimmunity against AQPs concerns the antibodies to AQP4 which are involved in the pathogenesis of neuromyelitis optica spectrum disorder (NMOSD), an autoimmune astrocytopathy, causing also CNS demyelination. The present review focuses on the discovery and the potential role of antibodies against AQP1 in the CNS, and their potential involvement in the pathophysiology of NMOSD. We describe (a) the several techniques developed for the detection of the AQP1-antibodies, with emphasis on methods that specifically identify antibodies targeting the extracellular domain of AQP1, i.e., those of potential pathogenic role, and (b) the available evidence supporting the pathogenic relevance of AQP1-antibodies in the NMOSD phenotype.

Muscle-specific kinase (MuSK) Myasthenia Gravis (MG) represents a prototypical antibody-mediated disease characterized by predominantly focal muscle weakness (neck, facial, and bulbar muscles) and fatigability. The pathogenic antibodies mostly belong to the immunoglobulin subclass (Ig)G4, a feature which attributes them their specific properties and pathogenic profile. On the other hand, acetylcholine receptor (AChR) MG, the most prevalent form of MG, is characterized by immunoglobulin (Ig)G1 and IgG3 antibodies to the AChR. IgG4 class autoantibodies are impotent to fix complement and only weakly bind Fc-receptors expressed on immune cells and exert their pathogenicity via interfering with the interaction between their targets and binding partners (e.g. between MuSK and LRP4). Cardinal differences between AChR and MuSK-MG are the thymus involvement (not prominent in MuSK-MG), the distinct HLA alleles, and core immunopathological patterns of pathology in neuromuscular junction, structure, and function. In MuSK-MG, classical treatment options are usually less effective (e.g. IVIG) with the need for prolonged and high doses of steroids difficult to be tapered to control symptoms. Exceptional clinical response to plasmapheresis and rituximab has been particularly observed in these patients. Reduction of antibody titers follows the clinical efficacy of anti-CD20 therapies, a feature implying the role of short-lived plasma cells (SLPB) in autoantibody production. Novel therapeutic monoclonal against B cells at different stages of their maturation (like plasmablasts), or against molecules involved in B cell activation, represent promising therapeutic targets. A revolution in autoantibody-mediated diseases is pharmacological interference with the neonatal Fc receptor, leading to a rapid reduction of circulating IgGs (including autoantibodies), an approach already suitable for AChR-MG and promising for MuSK-MG. New precision medicine approaches involve Chimeric autoantibody receptor T (CAAR-T) cells that are engineered to target antigen-specific B cells in MuSK-MG and represent a milestone in the development of targeted immunotherapies. This review aims to provide a detailed update on the pathomechanisms involved in MuSK-MG (cellular and humoral aberrations), fostering the understanding of the latest indications regarding the efficacy of different treatment strategies., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Vakrakou, Karachaliou, Chroni, Zouvelou, Tzanetakos, Salakou, Papadopoulou, Tzartos, Voumvourakis, Kilidireas, Giannopoulos, Tsivgoulis and Tzartos.)

Neurofilament light chain (NfL), is a neuron-specific cytoskeletal protein detected in extracellular fluid following axonal damage. Extensive research has focused on NfL quantification in CSF, establishing it as a prognostic biomarker of disability progression in Multiple Sclerosis (MS). Our study used a new commercially available Enzyme-Linked Immunosorbent Assay (ELISA) kit and Single Molecular Array (Simoa) advanced technology to assess serum NfL levels in MS patients and Healthy Controls (HC). Verifying the most accurate, cost-effective methodology will benefit its application in clinical settings. Blood samples were collected from 54 MS patients and 30 HC. Protocols accompanying the kits were followed. The ELISA thershold was set as 3 S.D. above the mean of the HC. For Simoa, the Z-score calculation created by Jens Kuhle's group was applied (with permission). Samples exceeding the threshold or z-score ≥1.5 indicated subclinical disease activity. To our knowledge, this is the first study to find strong-positive correlation between ELISA and Simoa for the quantification of NfL in serum (r = 0.919). Despite the strong correlation, Simoa has better analytical sensitivity and can detect small changes in samples making it valuable in clinical settings. Further research is required to evaluate whether serum NfL quantification using ELISA could be utilized to predict disability progression.

Introduction: Cognitive impairment is a core symptom of multiple sclerosis, leading to disability in 40-70% of patients. The most common cognitive domains affected by MS are information processing speed, complex attention, executive functions and less frequently, episodic declarative memory. Cardiovascular disease comorbidities have been shown to increase the decline rate in many neurological conditions. Our study aims to examine the possible impact of CVD risk factors in the cognitive decline rate of PwMS., Methods: Over the course of a year, 248 PwMS with and without Cardiovascular comorbidity were cognitively evaluated using the written version of SDMT and the MoCA., Results: Compared to control, MS patients with comorbid CVD had greater general cognitive decline and decreased processing speed. Patients with comorbid diabetes and dyslipidemia had the highest impairment, followed by those with hypertension, compared to the control group and those patients with a high BMI., Conclusion: The presence of cardiovascular comorbidities and especially dyslipidemia increases the rate of cognitive decline in MS patients. In such cases, patients should be evaluated every 6 months instead of a year and the use of the SDMT is advised since it's time efficient,it requires minimal training and correlates with MRI findings., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Nicotinic acetylcholine receptors (nAChRs) are widely expressed in many and diverse cell types, participating in various functions of cells, tissues and systems. In this review, we focus on the autoimmunity against neuronal nAChRs, the specific autoantibodies and their mechanisms of pathological action in selected autoimmune diseases. We summarize the current relevant knowledge from human diseases as well as from experimental models of autoimmune neurological disorders related to antibodies against neuronal nAChR subunits. Despite the well-studied high immunogenicity of the muscle nAChRs where autoantibodies are the main pathogen of myasthenia gravis, autoimmunity to neuronal nAChRs seems infrequent, except for the autoantibodies to the ganglionic receptor, the α3 subunit containing nAChR (α3-nAChR), which are detected and are likely pathogenic in Autoimmune Autonomic Ganglionopathy (AAG). We describe the detection, presence and function of these antibodies and especially the recent development of a cell-based assay (CBA) which, contrary to until recently available assays, is highly specific for AAG. Rare reports of autoantibodies to the other neuronal nAChR subtypes include a few cases of antibodies to α7 and/or α4β2 nAChRs in Rasmussen encephalitis, schizophrenia, autoimmune meningoencephalomyelitis, and in some myasthenia gravis patients with concurrent CNS symptoms. Neuronal-type nAChRs are also present in several non-excitable tissues, however the presence and possible role of antibodies against them needs further verification. It is likely that the future development of more sensitive and disease-specific assays would reveal that neuronal nAChR autoantibodies are much more frequent and may explain the mechanisms of some seronegative autoimmune diseases., Competing Interests: Declaration of Competing Interest ST has shares in the research and diagnostic laboratory Tzartos NeuroDiagnostics. ST and JT have filed a patent on a cell-based method for detecting potentially pathogenic autoantibodies to neuronal nAChRs. RM received funding for Travel, Meeting attendance or Advisory Board participation from Alexion, Argenx, Biomarin, Catalyst, SANOFI, Regeneron and UCB. The authors report no conflicts of interest., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Anti-NMDAR encephalitis has been associated with multiple antigenic triggers (i.e., ovarian teratomas, prodromal viral infections) but whether geographic, climatic, and environmental factors might influence disease risk has not been explored yet. We performed a systematic review and a meta-analysis of all published papers reporting the incidence of anti-NMDAR encephalitis in a definite country or region. We performed several multivariate spatial autocorrelation analyses to analyze the spatial variations in the incidence of anti-NMDA encephalitis depending on its geographical localization and temperature. Finally, we performed seasonal analyses in two original datasets from France and Greece and assessed the impact of temperature using an exposure-lag-response model in the French dataset. The reported incidence of anti-NMDAR encephalitis varied considerably among studies and countries, being higher in Oceania and South America (0.2 and 0.16 per 100,000 persons-year, respectively) compared to Europe and North America (0.06 per 100,000 persons-year) ( p < 0.01). Different regression models confirmed a strong negative correlation with latitude (Pearson's R = -0.88, p < 0.00001), with higher incidence in southern hemisphere countries far from the equator. Seasonal analyses showed a peak of cases during warm months. Exposure-lag-response models confirmed a positive correlation between extreme hot temperatures and the incidence of anti-NMDAR encephalitis in France ( p = 0.03). Temperature analyses showed a significant association with higher mean temperatures and positive correlation with higher ultraviolet exposure worldwide. This study provides the first evidence that geographic and climatic factors including latitude, mean annual temperature, and ultraviolet exposure, might modify disease risk.

Introduction Dizziness and vertigo represent well-established symptoms of COVID-19. An overexpression of cytokines, a condition often described with the term "cytokine storm" or "hypercytokinemia", is a key characteristic of SARS-Cov-2 infection and plays a pivotal role in disease progression and prognosis. Among them, IL-6 is of major importance.  Purpose The purpose of this study is to investigate any probable IL-6 serum titer difference in COVID-19 patients with vertigo (V+) or without vertigo (V-) admitted to the COVID-19 internal medicine departments of Attikon University Hospital, Athens, Greece, within 12 months. Methods The sample consisted of 52 COVID-19 patients who were diagnosed between January 1, 2020, and December 31, 2020. Of those, 31 reported vertigos during their admission (V+), while the remaining 21 COVID-19 patients did not complain of such symptoms (V-). Results Higher IL-6 serum levels post-COVID-19 infections lead to higher incidence rates of vertigo symptoms (p<.005), regardless of gender and age (p.005)., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Kitsos et al.)

Myasthenia gravis (MG) is an autoimmune disease caused by antibodies targeting the neuromuscular junction (NJ) of skeletal muscles. The major MG autoantigen is nicotinic acetylcholine receptor. Other autoantigens at the NJ include MuSK, LRP4 and agrin. Autoantibodies to the intra-sarcomeric striated muscle-specific gigantic protein titin, although not directed to the NJ, are invaluable biomarkers for thymoma and MG disease severity. Thymus and thymoma are critical in MG mechanisms and management. Titin autoantibodies bind to a 30 KDa titin segment, the main immunogenic region (MIR), consisting of an Ig-FnIII-FnIII 3-domain tandem, termed I109-I111. In this work, we further resolved the localization of titin epitope(s) to facilitate the development of more specific anti-titin diagnostics. For this, we expressed protein samples corresponding to 8 MIR and non-MIR titin fragments and tested 77 anti-titin sera for antibody binding using ELISA, competition experiments and Western blots. All anti-MIR antibodies were bound exclusively to the central MIR domain, I110, and to its containing titin segments. Most antibodies were bound also to SDS-denatured I110 on Western blots, suggesting that their epitope(s) are non-conformational. No significant difference was observed between thymoma and non-thymoma patients or between early- and late-onset MG. In addition, atomic 3D-structures of the MIR and its subcomponents were elucidated using X-ray crystallography. These immunological and structural data will allow further studies into the atomic determinants underlying titin-based autoimmunity, improved diagnostics and how to eventually treat titin autoimmunity associated co-morbidities.