Ganglionic Acetylcholine Receptor Research Articles

Chronic lymphoproliferative disorder of natural killer cells-related neurolymphomatosis with severe autonomic dysfunction: a case report

BackgroundChronic lymphoproliferative disorder of natural killer cells (CLPD-NK) is a rare disease characterized by a persistent increase in NK cells in peripheral blood and is generally asymptomatic. If present, symptoms may include fatigue, B symptoms (fever, night sweats, and unintentional weight loss), autoimmune-associated diseases, splenomegaly, and infection due to neutropenia. Peripheral neuropathy, however, is uncommon with an incidence of 3%. Neurolymphomatosis is a neurological manifestation of non-Hodgkin lymphoma and leukemia in which neurotropic neoplastic cells infiltrate the nerves. Moreover, neurolymphomatosis caused by CLPD-NK is extremely rare, with even fewer cases of autonomic dysfunction. We report a case of neurolymphomatosis associated with CLPD-NK and developed autonomic dysfunction, including orthostatic hypotension and gastrointestinal symptoms.Case presentationThe patient was a 61-year-old male who was referred to our hospital for leukocytosis. He was diagnosed with CLPD-NK; however, was untreated since he had no hepatosplenomegaly, and other systemic symptoms. He later developed numbness in his lower extremities. Cerebral spinal fluid examination revealed a markedly elevated protein level of 140 mg/dL, and contrast-enhanced magnetic resonance imaging showed bilateral L4 and 5 nerve roots with enlargement and contrast effect. An immune-mediated polyradiculoneuropathy was suspected, and he was treated with intravenous methylprednisolone and immunoglobulin followed by oral prednisolone and cyclosporine. Although his symptoms were relieved by the immunotherapy, significant autonomic dysfunction, including intractable diarrhea, decreased sweating, and orthostatic hypotension, appeared. Additionally, tests for onconeuronal antibodies, ganglionic nicotinic acetylcholine receptor (gAChR) antibody, NF155, CNTN1, Caspr1 antibody, and anti-ganglioside antibodies were all negative. A sural nerve biopsy revealed lymphocytic infiltration, and immunohistochemical staining of lymphocytes confirmed the infiltration of NK and T cells. Therefore, a diagnosis of neurolymphomatosis caused by CLPD-NK was made, and chemotherapy led to partial symptom improvement.ConclusionsWe experienced a case of pathologically diagnosed neurolymphomatosis with autonomic dysfunction associated with CLPD-NK. In cases of subacute to chronic autonomic dysfunction, paraneoplastic neuropathy, amyloidosis, and autoimmune autonomic ganglionopathy are considered; however neurolymphomatosis caused by CLPD-NK, an important cause of autonomic dysfunction, is not. In difficult to make diagnosis, aggressive nerve biopsy is required.

Fluorescence-detection size-exclusion chromatography specifically detects autoantibodies targeting the ganglionic acetylcholine receptor in patients with autoimmune autonomic ganglionopathy

Autoimmune autonomic ganglionopathy (AAG) is a rare disease wherein autoantibodies target the ganglionic acetylcholine receptor (gAChR). Current diagnosis in the United States depends upon clinical symptoms and positive autoantibody detection using a radioimmunoprecipitation assay (RIA). Here we offer a proof-of-principle study on an alternative method, fluorescence-detection size-exclusion-chromatography (FSEC). We show FSEC can detect autoantibodies against gAChR from patient sera but not healthy controls or samples from other autoimmune diseases. We compare FSEC to RIA and find good correlation. We discuss potential advantages of using FSEC as an alternative or as a first-step diagnostic prior to pursuing existing methodologies.

Autoimmune Autonomic Ganglionopathy and Acute Autonomic Sensory Neuropathy

Autoimmune autonomic ganglionopathy (AAG) and acute autonomic sensory neuropathy (AASN) are immune-mediated neuropathies that affect the autonomic and/or dorsal root ganglia. Autoantibodies against the nicotinic ganglionic acetylcholine receptor (gAChR) detected in the sera of patients with AAG play a key role in the pathogenesis of this condition. Notably, gAChR antibodies are not detected in the sera of patients with AASN. Currently, AAG and AASN are not considered to be on the same spectrum with regard to disease concept based on clinical symptoms and laboratory findings. However, extra-autonomic brain symptoms (including psychiatric symptoms and personality changes) and endocrine disorders occur in both diseases, which suggests shared pathophysiology between the two conditions.

The Presence of Ganglionic Acetylcholine Receptor Antibodies in Sera from Patients with Functional Gastrointestinal Disorders: A Preliminary Study.

Functional gastrointestinal disorders (FGIDs), including functional dyspepsia (FD) and irritable bowel syndrome (IBS), are characterized by chronic and recurrent gastrointestinal symptoms. Clinically, FD and IBS often resemble gastrointestinal dysmotility caused by autoimmune autonomic neuropathy. We examined the seropositive frequency of autoantibodies against ganglionic nicotinic acetylcholine receptors (gnAChRs) in patients presenting with FGIDs. To elucidate the seropositivity of gnAChR antibodies and the clinical features of seropositive FD and IBS. We measured autoantibodies against the gnAChR α3 and β4subunits using luciferase immunoprecipitation systems. Serum samples from patients with any autonomic symptoms were obtained from hospitals in Japan between January 2012 and August 2018 (1787 serum samples of 1381 patients). We selected FD and IBS patients and compared the clinical characteristics and prevalence of autonomic symptoms between those with seropositive and seronegative IBS and FD. Nine IBS and two FD cases (one comorbid case with IBS) were found. We found four patients (36.4%) in whom gnAChR antibodies were positive in these eleven patients. Sicca symptoms were observed in three of four cases (75%) of seropositive FGID compared with zero of seven cases (0%) of seronegative FGID. We found patients with gnAChR antibodies in FD and IBS patients. These data will be valuable for elucidating the pathophysiology of these FGIDs and developing new treatment strategies.

Autoimmune Autonomic Neuropathy: From Pathogenesis to Diagnosis.

Autoimmune autonomic ganglionopathy (AAG) is a disease of autonomic failure caused by ganglionic acetylcholine receptor (gAChR) autoantibodies. Although the detection of autoantibodies is important for distinguishing the disease from other neuropathies that present with autonomic dysfunction, other factors are important for accurate diagnosis. Here, we provide a comprehensive review of the clinical features of AAG, highlighting differences in clinical course, clinical presentation, and laboratory findings from other neuropathies presenting with autonomic symptoms. The first step in diagnosing AAG is careful history taking, which should reveal whether the mode of onset is acute or chronic, followed by an examination of the time course of disease progression, including the presentation of autonomic and extra-autonomic symptoms. AAG is a neuropathy that should be differentiated from other neuropathies when the patient presents with autonomic dysfunction. Immune-mediated neuropathies, such as acute autonomic sensory neuropathy, are sometimes difficult to differentiate, and therefore, differences in clinical and laboratory findings should be well understood. Other non-neuropathic conditions, such as postural orthostatic tachycardia syndrome, chronic fatigue syndrome, and long COVID, also present with symptoms similar to those of AAG. Although often challenging, efforts should be made to differentiate among the disease candidates.

Autoantibodies against gAChR in humans and mouse models of autoimmune autonomic ganglionopathy

AbstractThe ganglionic nicotinic acetylcholine receptor (gAChR) mediates fast synaptic transmission in all peripheral autonomic ganglia (sympathetic, parasympathetic, and enteric). Over the last two decades, evidence has accumulated for a role of autoantibodies against gAChR in the development of autoimmune autonomic ganglionopathy (AAG). In this review we provide an updated overview of the field, with a highlight on the role of autoimmunity against gAChR in the pathogenesis of AAG. Clinical data as well as findings from experimental disease models are summarized in sections focusing on the presence of autoantibodies against gAChR in patients with AAG, the function of gAChR antibodies, the association of antibodies against gAChR with AAG‐related phenotypes, the in vivo pathogenicity of transferred autoantibodies against gAChR in mice, and mouse models of the disease induced by immunization with the nicotinic AChR. Based on a comprehensive assessment of the currently available data, we propose a hypothetical model for the role of autoantibodies against gAChR in the pathogenesis of AAG.

Autoimmune Autonomic Ganglionopathy: Solving the 10 Assignments

Autoimmune autonomic ganglionopathy (AAG) is a rare acquired immune-mediated neurological disease that causes various autonomic symptoms. AAG is induced by autoantibodies for the α3 and β4 subunits of the ganglionic acetylcholine receptor (gAChR). gAChR antibodies mediate synaptic transmission in all autonomic ganglia, resulting in dysautonomia. Recent clinical and basic research topics in AAG include the following: 1)analysis of clinical features; 2)novel methods for gAChR antibody detection; 3)efficacy of combined immunotherapy; 4)novel experimental AAG; 5)COVID-19 and mRNA COVID-19 vaccination and its association with autonomic dysfunction; and 6)dysautonomia as an immune-related adverse event of immune checkpoint inhibitors in cancer therapy. The author and his collaborators have previously established "10 assignments" to understand the basic research and clinical issues of AAG. In this review, the author describes the current status of research on each of the "10 assignments," incorporating research trends over the last five years.

Disconnected Cardiac Autonomic Nerves in Genetic Ganglionic Acetylcholine Receptor Alpha-3 Subunit Deficiency.

HomeHypertensionAhead of PrintDisconnected Cardiac Autonomic Nerves in Genetic Ganglionic Acetylcholine Receptor Alpha-3 Subunit Deficiency No AccessResearch ArticleRequest AccessAboutView PDFSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toNo AccessResearch ArticleRequest AccessDisconnected Cardiac Autonomic Nerves in Genetic Ganglionic Acetylcholine Receptor Alpha-3 Subunit Deficiency Karsten Heusser, Florian Erger, Ulrich Ebner, Barbara Namer, Graeme Eisenhofer, Carl-Albrecht Haensch, Henning Weis, Matthias Schmidt, Alexander Drzezga, Jens Tank, Christian Netzer and Jens Jordan Karsten HeusserKarsten Heusser https://orcid.org/0000-0002-2571-5585 Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany (K.H., H.W., J.T., J.J.). *K. Heusser and F. Erger contributed equally. Search for more papers by this author , Florian ErgerFlorian Erger https://orcid.org/0000-0002-2768-1702 Institute of Human Genetics, Medical Faculty, University of Cologne, Germany (F.E., C.N.). *K. Heusser and F. Erger contributed equally. Search for more papers by this author , Ulrich EbnerUlrich Ebner https://orcid.org/0009-0002-4648-8497 Internal Medicine Practice, Regensburg, Germany (U.E.). Search for more papers by this author , Barbara NamerBarbara Namer https://orcid.org/0000-0001-7500-2842 Institute of Physiology and Pathophysiology, Friedrich Alexander University Erlangen-Nuremberg, Germany (B.N.). Research Group Neuroscience, Interdisciplinary Centre for Clinical Research within the Faculty of Medicine at the RWTH Aachen University, Germany (B.N.). Department for Physiology, Faculty of Medicine at the RWTH Aachen University, Germany (B.N.). Search for more papers by this author , Graeme EisenhoferGraeme Eisenhofer Institute of Clinical Chemistry and Laboratory Medicine, University Hospital Carl Gustav Carus, Medical Faculty, Technical University Dresden, Germany. (G.E.) University Hospital Carl Gustav Carus, Medical Faculty Carl Gustav Carus and Department of Medicine III, University Hospital Carl Gustav Carus, Medical Faculty, Technical University Dresden, Germany. (G.E.) Search for more papers by this author , Carl-Albrecht HaenschCarl-Albrecht Haensch https://orcid.org/0000-0001-6479-0265 Kliniken Maria Hilf Mönchengladbach, Autonomic Laboratory, Department of Neurology, Faculty of Health, University of Witten/Herdecke, Mönchengladbach, Germany (C.-A.H.). Search for more papers by this author , Henning WeisHenning Weis https://orcid.org/0000-0001-8638-3281 Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany (K.H., H.W., J.T., J.J.). Department of Nuclear Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Germany (H.W., M.S., A.D.). Search for more papers by this author , Matthias SchmidtMatthias Schmidt https://orcid.org/0000-0002-7519-8897 Department of Nuclear Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Germany (H.W., M.S., A.D.). Search for more papers by this author , Alexander DrzezgaAlexander Drzezga Department of Nuclear Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Germany (H.W., M.S., A.D.). Search for more papers by this author , Jens TankJens Tank https://orcid.org/0000-0002-5672-1187 Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany (K.H., H.W., J.T., J.J.). Search for more papers by this author , Christian NetzerChristian Netzer Institute of Human Genetics, Medical Faculty, University of Cologne, Germany (F.E., C.N.). †C. Netzer and J. Jordan contributed equally. Search for more papers by this author and Jens JordanJens Jordan Correspondence to: Jens Jordan, Institute for Aerospace Medicine, Linder Hoehe, 51147 Cologne, Germany. Email E-mail Address: [email protected] https://orcid.org/0000-0003-4518-0706 Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany (K.H., H.W., J.T., J.J.). †C. Netzer and J. Jordan contributed equally. Search for more papers by this author Originally published10 May 2023https://doi.org/10.1161/HYPERTENSIONAHA.123.21172Hypertension. 2023;0Footnotes*K. Heusser and F. Erger contributed equally.†C. Netzer and J. Jordan contributed equally.For Sources of Funding and Disclosures, see page XXX.Correspondence to: Jens Jordan, Institute for Aerospace Medicine, Linder Hoehe, 51147 Cologne, Germany. Email jens.[email protected]de Previous Back to top Next FiguresReferencesRelatedDetails Advertisement Article InformationMetrics © 2023 American Heart Association, Inc.https://doi.org/10.1161/HYPERTENSIONAHA.123.21172PMID: 37161764 Originally publishedMay 10, 2023 KeywordsCHRNA3autonomic failureganglionic acetylcholine receptorsympathetic nervous systemPDF download Advertisement SubjectsAutonomic Nervous SystemGeneticsMechanismsNuclear Cardiology and PETPathophysiology

Autoimmune Encephalitis With Ganglionic a3-AChR Antibodies

Objective To describe a case of autoimmune encephalitis presented as new onset refractory nonconvulsive status epilepticus and autonomic failure caused by alpha-3 ganglionic acetylcholine receptor autoantibodies (a3-AChR Ab). Background Autoimmune autonomic ganglionopathy (AAG) is rare acquired dysautonomia in adults due to a3-AChR Ab. A patient typically presents with subacute autonomic dysfunction, and encephalitis has not been reported yet. Design/Methods NA. Results A 60 years old female presented with progressive worsening of mental status for two weeks. Vital signs were normal. The patient was somnolent, nonverbal, with tonic non-reactive pupils on the exam. CT head showed multiple subcortical hypodensities. MRI brain demonstrated T2-FLAIR hyperintense lesions in bifrontal lobes sparing the U-fibers, with abnormal leptomeningeal/pial perivenular type enhancement. MRI C/T spine, CT chest/Abd/pelvis were negative. Although serum and CSF testing showed inflammatory markers, meningoencephalitis and autoimmune encephalitis panel were negative, except for the serum Paraneoplastic panel was positive with high titer a3-AChR Abs. EEG showed nonconvulsive status epilepticus, which required management with three antiseizure medications. Initially, the patient had little response to empirical pulse methylprednisolone therapy. Later showed good clinical response with plasmapheresis. Later on she presented with nonobstructive small bowel obstruction, resolved with another pulse steroid therapy, discharged on dexamethasone taper. On a three-month follow-up, the patient was in near clinical remission, supported with resolved lesions on a repeat MRI. She never relapsed after two years of follow-up. Conclusions Studies have shown that a3-AChR Abs can result in diverse neurological manifestations, mainly dysautonomia. Our patient presented with encephalitis, dysautonomia, and refractory nonconvulsive status epilepticus. Scans suggested diffuse leukoencephalopathy, patient was found to have high 3-ACHR antibody seropositivity. Initially, the patient was steroid-resistant but showed clinical improvement with plasmapheresis. We have described an interesting case of encephalitis likely associated with a3-AChR Ab that has not been previously described. More studies are required to confirm this association.

Renal Transplantation in Pure Autonomic Failure.

Renal Transplantation in Pure Autonomic Failure.

Effectiveness of treatment for 31 patients with seropositive autoimmune autonomic ganglionopathy in Japan.

Background:Autoimmune autonomic ganglionopathy (AAG) is characterized by serum autoantibodies against the ganglionic acetylcholine receptor (gAChR). Immunomodulatory treatments may alleviate AAG symptoms, but the most appropriate treatment strategy is unclear.Objective:This study aimed to confirm the effectiveness of treatments, particularly immunotherapy, in patients with seropositive AAG in Japan, as well as to determine the most effective treatment and the best assessment method for clinical response to treatment.Methods:We collected data from a previous cohort study of patients with seropositive AAG. The clinical autonomic and extra-autonomic symptoms were objectively counted and subjectively assessed using the modified Composite Autonomic Symptom Score. Post-treatment changes in the gAChR antibody level were evaluated.Results:Thirty-one patients received immunotherapy. Among them, 19 patients received intravenous methylprednisolone; 27, intravenous immunoglobulin; 3, plasma exchange; 18, oral steroids; 2, tacrolimus; 1, cyclosporine; and 1, mycophenolate mofetil. Patients who received immunotherapy showed improvements in the total number of symptoms (from 6.2 ± 2.0 to 5.1 ± 2.0) and modified Composite Autonomic Symptom Score (from 37.4 ± 15.3 to 26.6 ± 12.8). Orthostatic intolerance, sicca, and gastrointestinal symptoms were ameliorated by immunotherapy. Immunotherapy decreased the antibody levels (gAChRα3 antibodies, from 2.2 ± 0.4 to 1.9 ± 0.4, p = 0.08; gAChRβ4 antibodies, from 1.6 ± 0.1 to 1.0 ± 0.2, p = 0.002), but antibody levels increased in 10 patients despite immunotherapy. The rate of improvement in the total number of symptoms was higher in patients with combined therapy than in patients with non-combined therapy (70.7% vs 28.6%).Conclusions:The scores in many items on the rating scale decreased after immunotherapy in patients with seropositive AAG, particularly in the combined immunotherapy group. However, more accurate assessment scales for clinical symptoms and multicenter randomized, placebo-controlled prospective studies are warranted to establish future treatment strategies.

First Case of Association between Autoimmune Autonomic Ganglionopathy (AAG) and Myeloproliferative Neoplasms (MPNs)

IntroductionAutoimmune autonomic ganglionopathy (AAG) is a rare disease that presents with different autonomic symptoms and positive autoantibodies against the ganglionic acetylcholine receptor (gAChR) in 50 % of the cases. Eighty percent of seropositive patient has extra-autonomic manifestations. Extra-autonomic manifestations include sensory disturbance, central nervous system involvement, endocrine disorders autoimmune diseases, and cancers. It has been reported with various malignancies, such as small lung cancer, thymoma, ovarian tumors and others.MethodWe report a case from MD Anderson cancer center (MDACC) and to our knowledge it is first case in literature of a patient Autoimmune autonomic ganglionopathy associated with primary myelofibrosisResultA 55-year-old African American male diagnosed with JAK2 V617F positive primary myelofibrosis in 2005 and placed on observation until September 2012 when he was referred to MDACC for further management. He was started on protocol with Ruxolitinib + lenalidomide and did well initially, but during the course of treatment, he started to experience leg weakness. Initially in the left leg and then the right leg. lenalidomide was placed on hold and in April 2015, ruxolitinib was held as well. On examination he has left leg weakness in addition to weak hand grip on the same side.On Further evaluation, he was diagnosed with inclusion body myositis after muscle biopsy He was then lost to follow up and followed with outside hematologistIn February 2020, he developed cytopenias and was referred back to MDACC for management. He was seen and we performed a bone marrow shortly thereafter. He continued to have PMF, molecular, cytogenetics could not be performed on bone marrow due to dry tap. Patient started on “investigational agent. In early 2021 patient started to have orthostatic hypotension and syncope. Serum paraneoplastic antibody panel revealed acetylcholine Receptor Gang Neuronal Ab.The above finding along with his automimic symptoms consists with diagnosis of autoimmune autonomic ganglionopathy.ConclusionAutoimmune autonomic ganglionopathy (AAG) with extra-autonomic manifestations is a very rare and not well known. It is reported before to be associated with solid malignancy, we describe here first association with hematological malignancy which is primary myelofibrosis. We aim to add this to literature, and to increase the knowledge and awareness of both hematologists and neurologists about this association and possible other hematological malignancies may be reported in the future DisclosuresVerstovsek: Celgene: Consultancy, Research Funding; CTI BioPharma: Research Funding; Genentech: Research Funding; Promedior: Research Funding; PharmaEssentia: Research Funding; Ital Pharma: Research Funding; Protagonist Therapeutics: Research Funding; Roche: Research Funding; Gilead: Research Funding; Incyte Corporation: Consultancy, Research Funding; NS Pharma: Research Funding; Blueprint Medicines Corp: Research Funding; AstraZeneca: Research Funding; Novartis: Consultancy, Research Funding; Sierra Oncology: Consultancy, Research Funding; Constellation: Consultancy; Pragmatist: Consultancy.

Evaluation of commercially available antibodies and fluorescent conotoxins for the detection of surface ganglionic acetylcholine receptor on the neuroblastoma cell line, IMR-32 by flow cytometry

Commercially available antibodies that bind to the human muscle acetylcholine receptor (ACHR) have been validated previously for flow cytometric use (Keefe et al., 2009; Leite et al., 2008; Lozier et al., 2015). Despite a multitude of commercially available antibodies to other nicotinic ACHRs, validation in a wide variety of immunoassay formats is lacking; when studied, a large proportion of these antibodies have been deemed not fit for most research purposes (Garg and Loring, 2017).We have recently described a flow cytometric immunomodulation assay for the diagnosis of Autoimmune Autonomic Ganglionopathy (AAG) (Urriola et al., 2021) that utilises the monoclonal antibody mab35(Urriola et al., 2021) which is specific for ganglionic ACHR (gnACHR) that contain α3 subunits (Vernino et al., 1998). Other fluorescent ligands for α3-gnACHR have not been validated for flow cytometric use.We investigated 7 commercially sourced antibodies and 3 synthetic fluorescent novel conotoxins purported to specifically bind to the extracellular domains of the gnACHR, and compared the results to staining by mab35, using flow cytometry with the neuroblastoma cell line IMR-32. We also evaluated the degree of non-specific binding by depleting the cell membrane of the relevant acetylcholine receptor with a pre-incubation step involving the serum from a patient with Autoimmune Autonomic Ganglionopathy containing pathogenic antibodies to the ganglionic acetylcholine receptor. None of the assessed conotoxins, and only one antibody (mab35) was found to perform adequately in flow cytometric staining of the native ganglionic acetylcholine receptor.

Autoimmune Neurogenic Dysphagia.

Autoimmune neurogenic dysphagia refers to manifestation of dysphagia due to autoimmune diseases affecting muscle, neuromuscular junction, nerves, roots, brainstem, or cortex. Dysphagia is either part of the evolving clinical symptomatology of an underlying neurological autoimmunity or occurs as a sole manifestation, acutely or insidiously. This opinion article reviews the autoimmune neurological causes of dysphagia, highlights clinical clues and laboratory testing that facilitate early diagnosis, especially when dysphagia is the presenting symptom, and outlines the most effective immunotherapeutic approaches. Dysphagia is common in inflammatory myopathies, most prominently in inclusion body myositis, and is frequent in myasthenia gravis, occurring early in bulbar-onset disease or during the course of progressive, generalized disease. Acute-onset dysphagia is often seen in Guillain–Barre syndrome variants and slowly progressive dysphagia in paraneoplastic neuropathies highlighted by the presence of specific autoantibodies. The most common causes of CNS autoimmune dysphagia are demyelinating and inflammatory lesions in the brainstem, occurring in patients with multiple sclerosis and neuromyelitis optica spectrum disorders. Less common, but often overlooked, is dysphagia in stiff-person syndrome especially in conjunction with cerebellar ataxia and high anti-GAD autoantibodies, and in gastrointestinal dysmotility syndromes associated with autoantibodies against the ganglionic acetyl-choline receptor. In the setting of many neurological autoimmunities, acute-onset or progressive dysphagia is a potentially treatable condition, requiring increased awareness for prompt diagnosis and early immunotherapy initiation.

A Flow Cytometric Assay to Detect Functional Ganglionic Acetylcholine Receptor Antibodies by Immunomodulation in Autoimmune Autonomic Ganglionopathy.

Autoimmune Autonomic Ganglionopathy (AAG) is an uncommon immune-mediated neurological disease that results in failure of autonomic function and is associated with autoantibodies directed against the ganglionic acetylcholine receptor (gnACHR). The antibodies are routinely detected by immunoprecipitation assays, such as radioimmunoassays (RIA), although these assays do not detect all patients with AAG and may yield false positive results. Autoantibodies against the gnACHR exert pathology by receptor modulation. Flow cytometric analysis is able to determine if this has occurred, in contrast to the assays in current use that rely on immunoprecipitation. Here, we describe the first high-throughput, non-radioactive flow cytometric assay to determine autoantibody mediated gnACHR immunomodulation. Previously identified gnACHR antibody seronegative and seropositive sera samples (RIA confirmed) were blinded and obtained from the Oxford Neuroimmunology group along with samples collected locally from patients with or without AAG. All samples were assessed for the ability to cause gnACHR immunomodulation utilizing the prototypical gnACHR expressing cell line, IMR-32. Decision limits were calculated from healthy controls, and Receiver Operating Characteristic (ROC) curves were constructed after unblinding all samples. One hundred and ninety serum samples were analyzed; all 182 expected negative samples (from healthy controls, autonomic disorders not thought to be AAG, other neurological disorders without autonomic dysfunction and patients with Systemic Lupus Erythematosus) were negative for immunomodulation (<18%), as were the RIA negative AAG and unconfirmed AAG samples. All RIA positive samples displayed significant immunomodulation. There were no false positive or negative samples. There was perfect qualitative concordance as compared to RIA, with an Area Under ROC of 1. Detection of Immunomodulation by flow cytometry for the identification of gnACHR autoantibodies offers excellent concordance with the gnACHR antibody RIA, and overcomes many of the shortcomings of immunoprecipitation assays by directly measuring the pathological effects of these autoantibodies at the cellular level. Further work is needed to determine the correlation between the degree of immunomodulation and disease severity.

GAChR antibodies in children and adolescents with acquired autoimmune dysautonomia in Japan.

ObjectivePatients with acquired autonomic dysfunction may have antibodies specific to the ganglionic nicotinic acetylcholine receptor (gAChR). However, the clinical features of children and adolescents with acquired autonomic dysfunction (AAD) remain unclear. This study aimed to determine the clinical features of pediatric patients with acquired autonomic dysfunction.MethodsThis study retrospectively examined a series of patients of AAD with serum gAChR antibodies who were referred to our laboratory for antibody testing between January 2012 and April 2019. The study included 200 patients (<20 years, 20 cases; ≥20 years, 175 cases) with clinical features of AAD.ResultsUpon comparing pediatric and adult patients, we found that antecedent infection and autonomic symptoms at onset with gastrointestinal symptoms occurred more frequently in children with AAD. We confirmed that four children (20.0%) met the diagnostic criteria for postural orthostatic tachycardia syndrome (POTS). A significantly higher number of children than adults had POTS (P = 0.002). In addition, upper GI dysfunction was more prevalent in children than in adults (P = 0.042). In particular, nausea and vomiting occurred in 60.0% of children with AAD and in 21.1% of adults (P < 0.001). The frequency of paralytic ileus was significantly higher in children with AAD (20.0%) relative to adults (6.3%) (P = 0.030). Regarding extra‐autonomic manifestations, encephalopathy was more frequent in children (15.0%) than in adults (1.1%) (P < 0.001).InterpretationPediatric AAD patients have their own clinical characteristics, and these features may be unique to children and adolescents.

Multimodal Biomarkers Quantify Recovery in Autoimmune Autonomic Ganglionopathy.

The objective of this study was to evaluate patients with ganglionic acetylcholine receptor antibody (gAChR-Ab) positive autoimmune autonomic ganglionopathy using a multimodal testing protocol to characterize their full clinical phenotype and explore biomarkers to quantify immunotherapy response. We conducted a cohort study of 13 individuals (7 women, 21-69 years of age) with autonomic failure and gAChR-Ab >100 pM identified between 2005 and 2019. From 2018, all patients were longitudinally assessed with cardiovascular, pupillary, urinary, sudomotor, lacrimal and salivary testing, and Composite Autonomic Symptom Score (COMPASS-31) autonomic symptom questionnaires. The orthostatic intolerance ratio was calculated by dividing change in systolic blood pressure over time tolerated on head-up tilt. Eleven patients received immunotherapy. At first assessment, all 13 patients had cardiovascular and pupillary impairments, 7 of 8 had postganglionic sudomotor dysfunction, 9 of 11 had urinary retention and xeropthalmia, and 6 of 8 had xerostomia. After immunotherapy, there were significant improvements in orthostatic intolerance ratio (33.3 [17.8-61.3] to 5.2 [1.4-8.2], p = 0.007), heart rate response to deep breathing (1.5 [0.0-3.3] to 4.5 [3.0-6.3], p = 0.02), pupillary constriction to light (12.0 [5.5-18.0] to 19.0 [10.6-23.8]%, p = 0.02), saliva production (0.01 [0.01-0.05] to 0.08 [0.02-0.20] g/min, p = 0.03), and COMPASS-31 scores (52 to 17, p = 0.03). Orthostatic intolerance ratio correlated with autonomic symptoms at baseline (r = 0.841, p = 0.01) and following immunotherapy (r = 0.889, p = 0.02). Immunofluorescence analyses of skin samples from a patient 32 years after disease onset showed loss of nerve fibers supplying the dermal autonomic adnexa and epidermis, with clear improvements following immunotherapy. Patients with autoimmune autonomic ganglionopathy demonstrated objective evidence of widespread sympathetic and parasympathetic autonomic failure, with significant improvements after immunotherapy. Quantitative autonomic biomarkers should be used to define initial deficits, guide therapeutic decisions, and document treatment response. ANN NEUROL 2021;89:753-768.

Ganglionic Acetylcholine Receptor Antibodies in Postural Tachycardia Syndrome.

Postural tachycardia syndrome (POTS), the most common form of dysautonomia, may be associated with autoimmunity in some cases. Autoantibodies against the ganglionic acetylcholine receptor (gAChR) have been reported in a minority of patients with POTS, but the prevalence and clinical relevance is unclear. Clinical information and serum samples were systematically collected from participants with POTS and healthy control volunteers (n = 294). The level of positive gAChR antibodies was classified as very low (0.02-0.05 nmol/L), low (0.05-0.2 nmol/L), and high (>0.2 nmol/L). Fifteen of 217 patients with POTS (7%) had gAChR antibodies (8 very low and 7 low). Six of the 77 healthy controls (8%) were positive (3 very low and 3 low). There were no clinical differences between seropositive and seronegative patients with POTS. Prevalence of gAChR antibody did not differ between POTS and healthy controls, and none had high antibody levels. Patients with POTS were not clinically different based on seropositivity. Low levels of gAChR antibodies are not clinically important in POTS.

A case of chronic postural tachycardia syndrome with positive anti-ganglionic acetylcholine receptor (gAChR) antibody

Postural orthostatic tachycardia syndrome (POTS) is a form of orthostatic intolerance characterized by symptoms such as lightheadedness, fainting, and brain fog that occur with a rapid elevation in heart rate when standing up from a reclining position. The etiology of POTS has yet to be established. However, a growing body of evidence suggests that POTS may be an autoimmune disorder such as autoimmune autonomic ganglionopathy, an acquired, immune-mediated form of diffuse autonomic failure. Many patients have serum antibodies that bind to the ganglionic acetylcholine receptors (gAChRs) in the autonomic ganglia. Herein, we describe a 39-year-old female patient with an eight-year history of orthostatic intolerance. POTS was diagnosed based on the findings of a head-up tilt test, in which a rapid increase in the patient's heart rate from 58 bpm in the lying position to 117 bpm in the upright position without orthostatic hypotension was observed. The POTS symptoms were refractory to various medications except for pyridostigmine bromide, which resulted in a partial resolution of her symptoms. Her serum was found to be strongly positive for anti-gAChR (β4 subunit) autoantibody (2.162 A.I., normal range: below 1.0). Based on these findings, a limited form of autoimmune POTS was diagnosed. After obtaining written informed consent, she was treated with intravenous immunoglobulin (IVIg) 400 mg/kg/day for five days, which led to clinical improvement by reducing her heart rate increase in the upright position. She was able to return to work with IVIg treatment at regular intervals. Our case provides further evidence of a potential autoimmune pathogenesis for POTS. Aggressive immunotherapy may be effective for POTS even in chronic cases.

Visualization of Spatially-Controlled Vasospasm by Sympathetic Nerve–Mediated ROCK Activation

Contraction of vascular smooth muscle is regulated primarily by calcium concentration and secondarily by ROCK activity within the cells. In contrast to the wealth of information regarding regulation of calcium concentration, little is known about the spatiotemporal regulation of ROCK activity in live blood vessels. Here, we report ROCK activation in subcutaneous arterioles in a transgenic mouse line that expresses a genetically encoded ROCK biosensor based on the principle of Fӧrster resonance energy transfer by two-photon excitation invivo imaging. Rapid vasospasm was induced upon laser ablation of arterioles, concomitant with a transient increase in calcium concentration in arteriolar smooth muscles. Unlike the increase in calcium concentration, vasoconstriction and ROCK activation continued for several minutes after irradiation. Both the ROCK inhibitor, fasudil, and the ganglionic nicotinic acetylcholine receptor blocker, hexamethonium, inhibited laser-induced ROCK activation and reduced the duration of vasospasm at the segments distant from the irradiated point. These observations suggest that vasoconstriction is initially triggered by a rapid surge of cytoplasmic calcium and then maintained by sympathetic nerve-mediated ROCK activation.