[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.

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.

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.

Unexpected High Prevalence of Lymphocytic Infiltrates in Myenteric Ganglions in Intestinal Inertia.

Intestinal inertia is a severe form of gut dysmotility that may require surgical resection. Loss of myenteric ganglion cells has been proposed as a possible etiology. Preclinical models have also suggested that virus infection-associated ganglionitis may be an alternative pathogenic factor. We determined to the extent intestinal inertia is associated with the lack of myenteric ganglion cells or ganglionitis using resection specimens from 27 intestinal inertia and 28 colon cancer patients. A hot spot approach with 5 HPFs was used for quantifying inflammatory cells. CD3, CD8, and CD20 immunohistochemistry was used to quantify T and B lymphocytes, along with subtyping the T-lymphocyte population by CD8. None of the intestinal inertia nor control cases showed the absence of myenteric ganglion cells. A total of 15 (55.6%) of the intestinal inertia cases showed inflammatory cell infiltration in the myenteric ganglion cells, compared with only 1 of 28 (3.6%) control cases (P<0.0001 by Fisher exact test). The inertia cases with inflammatory infiltrates were all associated predominantly with lymphocytes, including 3 cases (11.1%) with concurrent eosinophil infiltration, and 1 case (3.7%) with concurrent neutrophil infiltration. Furthermore, all 15 inertia cases with myenteric lymphocytic ganglionitis were associated with T lymphocytes (100%), including 1 case with a subset of concurrent B lymphocytes. The average CD3 count was 3.8 cells/HPF. CD8 immunohistochemical stain showed positive staining in 12 of the 15 cases (80%) with CD8-positive cells ranging from 1 to 8/HPF. In contrast, the only control case with lymphocytic ganglionitis showed mixed B and T lymphocytes and eosinophils. The high prevalence of T-lymphocyte infiltration in the myenteric ganglion in intestinal inertia cases suggests a possible pathogenic role.

Ganglionic Acetylcholine Receptor Antibodies and Autonomic Dysfunction in Autoimmune Rheumatic Diseases.

Autonomic neuropathy has been reported in autoimmune rheumatic diseases (ARD) including Sjögren's syndrome, systemic sclerosis, rheumatoid arthritis, and systemic lupus erythematosus. However, the pathophysiological mechanism underlying autonomic dysfunction remains unknown to researchers. On the other hand, autoimmune autonomic ganglionopathy (AAG) is an acquired immune-mediated disorder, which causes dysautonomia that is mediated by autoantibodies against ganglionic acetylcholine receptors (gAChRs). The purpose of this review was to describe the characteristics of autonomic disturbance through previous case reports and the functional tests used in these studies and address the importance of anti-gAChR antibodies. We have established luciferase immunoprecipitation systems to detect antibodies against gAChR in the past and determined the prevalence of gAChR antibodies in various autoimmune diseases including AAG and rheumatic diseases. Autonomic dysfunction, which affects lower parasympathetic and higher sympathetic activity, is usually observed in ARD. The anti-gAChR antibodies may play a crucial role in autonomic dysfunction observed in ARD. Further studies are necessary to determine whether anti-gAChR antibody levels are correlated with the severity of autonomic dysfunction in ARD.

A comprehensive analysis of the clinical characteristics and laboratory features in 179 patients with autoimmune autonomic ganglionopathy.

The clinical importance of autoantibodies against the ganglionic acetylcholine receptor (gAChR) remains to be fully elucidated. We aimed to identify the clinical characteristics of autoimmune autonomic ganglionopathy (AAG) in patients with gAChR autoantibodies. For this cohort investigation, serum samples were obtained from patients with AAG between 2012 and 2018 in Japan. We measured the levels of autoantibodies against gAChRα3 and gAChRß4 and evaluated clinical features, as well as assessing the laboratory investigation results among the included patients. A total of 179 patients tested positive for antibodies, including 116 gAChRα3-positive, 13 gAChRß4-positive, and 50 double antibody-positive patients. Seropositive AAG patients exhibited widespread autonomic dysfunction. Extra-autonomic manifestations including sensory disturbance, central nervous system involvement, endocrine disorders, autoimmune diseases, and tumours were present in 118 patients (83%). We observed significant differences in the frequencies of several autonomic and extra-autonomic symptoms among the three groups. Our 123I-metaiodobenzylguanidine myocardial scintigraphy analysis of the entire cohort revealed that the heart-to-mediastinum ratio had decreased by 80%. The present study is the first to demonstrate that patients with AAG who are seropositive for anti-gAChRß4 autoantibodies exhibit unique autonomic and extra-autonomic signs. Decreased cardiac uptake occurred in most cases, indicating that 123I- metaiodobenzylguanidine myocardial scintigraphy may be useful for monitoring AAG. Therefore, our findings indicate that gAChRα3 and gAChRß4 autoantibodies cause functional changes in postganglionic fibres in the autonomic nervous system and extra-autonomic manifestations in seropositive patients with AAG.

[Autoimmune autonomic ganglionopathy].

Autoimmune autonomic ganglionopathy (AAG) is an acquired immune-mediated disorder of widespread autonomic failure. Approximately half of the patients with AAG have the autoantibodies against the neuronal nicotinic acetylcholine receptor (AChR) in autonomic ganglia. These ganglionic AChR antibodies have the potential to mediate the synaptic transmission in sympathetic, parasympathetic, and enteric ganglia. Therefore, seropositive AAG patients exhibit various autonomic symptoms. Extra-autonomic manifestations (coexistence with brain involvement, sensory disturbance, endocrine disorders, autoimmune diseases and tumors) are present in many patients with AAG. The nicotinic AChRs comprise a family of abundantly expressed ligand-gated cation channels found throughout the central and peripheral nervous systems. Moreover, limited manifestations of autoimmune dysautonomia including autoimmune gastrointestinal dysmotility are newly recognized clinical entity. Although combined immunomodulatory therapy is beneficial for almost all patients with AAG, several case reports of some AAG patients with small benefit exist. This review focuses on the recent progress in the clinical approaches of AAG and its related disorders involving the role of autoantibodies and clinical practice.

[A case of encephalopathy showing various psychiatric and autonomic symptoms with positive anti-ganglionic acetylcholine receptor (gAChR) antibody].

An 84-year-old woman developed spontaneous recurring mutism. During the periods in which she was able to speak, she described that she had a peculiar delusion where her body was melting away. She did not obey orders although she was able to move her limbs spontaneously. Severe fluctuations in blood pressure measurements were observed; they were unaffected by postural changes. She also had urinary retention and constipation. Her psychiatric and autonomic symptoms showed marked daily and diurnal fluctuations. The brain MRI showed no abnormality in the limbic system or temporal lobes. The cerebrospinal fluid showed slightly elevated protein with normal cells counts. This case was initially thought to be an encephalopathy of unknown etiology. On subsequent testings she was shown to have positive anti-ganglionic acetylcholine receptor (gAChR) antibodies. Although the initial steroid pulse and intravenous immunoglobulin therapies markedly improved both psychiatric and autonomic symptoms, they turned ineffective in subsequent recurrences. We were not able to treat her with plasmapheresis or with other immunisuppressive drugs because of her poor general status, thus their effectiveness could not be determined. Judging from her clinical course, in which immunotherapy was effective although somewhat limited, a possible involvement of an autoimmune mechanism was suspected; however, the exact pathogenesis remains undetermined. It is possible that in this case there may have been an involvement of the immune system and that the patient might have had an encephalopathy with anti-gAChR antibodies.

Autoimmune autonomic ganglionopathy associated with Sjögren's syndrome presenting with recurrent abdominal distension.

A 65-year-old woman with Sjögren's syndrome presented with recurrent abdominal distension, constipation, weight loss, orthostatic dizziness, loss of sweating and incomplete emptying of the bladder. Gastrointestinal dilatation but no evidence of malignancy or obstruction was found on CT of the abdomen, oesophagogastroduodenoscopy or colonoscopy. Postvoiding residual urine volume was increased. Antiganglionic acetylcholine receptor antibody was positive. We diagnosed as autoimmune autonomic ganglionopathy. The patient responded to corticosteroid treatment. One year after treatment, she continued to have mild gastrointestinal symptoms, but overall condition was stable without further intervention.

Autoimmune autonomic ganglionopathy: an update on diagnosis and treatment.

INTRODUCTION: Autoimmune autonomic ganglionopathy (AAG) is an acquired immune-mediated disorder that leads to autonomic failure. The disorder is associated with autoantibodies to the ganglionic nicotinic acetylcholine receptor (gAChR). We subsequently reported that AAG is associated with an overrepresentation of psychiatric symptoms, sensory disturbance, autoimmune diseases, and endocrine disorders. Area covered: The aim of this review was to describe AAG and highlight its pivotal pathophysiological aspects, clinical features, laboratory examinations, and therapeutic options. Expert commentary: AAG is a complex neuroimmunological disease, these days considered as an autonomic failure with extra-autonomic manifestations (and various limited forms). Further comprehension of the pathophysiology of this disease is required, especially the mechanisms of the extra-autonomic manifestations should be elucidated. There is the possibility that the co-presence of antibodies that were directed against the other subunits in both the central and peripheral nAChRs in the serum of the AAG patients. Some patients improve with immunotherapies such as IVIg and/or corticosteroid and/or plasma exchange. 123I-MIBG myocardial scintigraphy may be a useful tool to monitor the therapeutic effects of immunotherapies.

Ganglionic Antibody Level as a Predictor of Severity of Autonomic Failure.

OBJECTIVE: To assess antibody level as a test of autonomic failure (AF) associated with ganglionic nicotinic acetylcholine receptor antibody (AChR-Ab) autoimmunity. PATIENTS AND METHODS: We searched the Mayo Clinic laboratory database of 926 ganglionic AChR-Ab-seropositive patients seen at our institution between October 1, 1997, and April 1, 2015, for initial level of 0.05 nmol/L or higher and contemporaneous autonomic reflex screen (standardized evaluation of adrenergic, cardiovagal, and sudomotor functions) from which Composite Autonomic Scoring Scale (CASS) scores could be calculated. RESULTS: Of 289 patients who met inclusion criteria, 163 (56.4%) were women, median age was 54 years (range, 10-87 years), median antibody level was 0.11 nmol/L (range, 0.05-22.10 nmol/L), and median CASS total score was 2.0 (range, 0-10). Using receiver operating characteristic curve analysis, a level above 0.40 nmol/L predicted severe AF (CASS score, ≥7) with 92% specificity and 56% sensitivity. For at least moderate AF (CASS score ≥4 and anhidrosis ≥25%), a level of at least 0.20 nmol/L had 80% specificity and 59% sensitivity. Levels below 0.20 nmol/L were not predictive of the presence or absence of AF. For predicting orthostatic hypotension, ganglionic AChR-Ab level had excellent specificity above 0.4 nmol/L but lacked sensitivity. Autoantibodies to additional targets were present in 61 patients (21.1%). CONCLUSION: Ganglionic AChR-Ab level of at least 0.40 nmol/L is a moderately sensitive and highly specific marker for severe AF, as is a level of at least 0.20 nmol/L for moderate AF if CASS score is coupled with anhidrosis of 25% or more, among patients with suspected ganglionic AChR-Ab autoimmune autonomic ganglionopathy. Antibody levels of less than 0.20 nmol/L have little clinical importance in the absence of clinical AF.

Anti-ganglionic AChR antibodies in Japanese patients with motility disorders.

BACKGROUND: The existence of several autoantibodies suggests an autoimmune basis for gastrointestinal (GI) dysmotility. Whether GI motility disorders are features of autoimmune autonomic ganglionopathy (AAG) or are related to circulating anti-ganglionic acetylcholine receptor (gAChR) antibodies (Abs) is not known. The aim of this study was to determine the associations between autonomic dysfunction, anti-gAChR Abs, and clinical features in patients with GI motility disorders including achalasia and chronic intestinal pseudo-obstruction (CIPO). METHODS: First study: retrospective cohort study and laboratory investigation. Samples from 123 patients with seropositive AAG were obtained between 2012 and 2017. Second study: prospective study. Samples from 28 patients with achalasia and 14 patients with CIPO were obtained between 2014 and 2016, and 2013 and 2017, respectively. In the first study, we analyzed clinical profiles of seropositive AAG patients. In the second study, we compared clinical profiles, autonomic symptoms, and results of antibody screening between seropositive, seronegative achalasia, and CIPO groups. RESULTS: In the first study, we identified 10 patients (8.1%) who presented with achalasia, or gastroparesis, or paralytic ileus. In the second study, we detected anti-gAChR Abs in 21.4% of the achalasia patients, and in 50.0% of the CIPO patients. Although patients with achalasia and CIPO demonstrated widespread autonomic dysfunction, bladder dysfunction was observed in the seropositive patients with CIPO as a prominent clinical characteristic of dysautonomia. CONCLUSIONS: These results demonstrate a significant prevalence of anti-gAChR antibodies in patients with achalasia and CIPO. Anti-gAChR Abs might mediate autonomic dysfunction, contributing to autoimmune mechanisms underlying these GI motility disorders.

[Anti-Ganglionic Acetylcholine Receptor Antibodies, Autoimmune Autonomic Ganglionopathy, and Related Disorders].

The clinical associations of the anti-ganglionic acetylcholine receptor (gAChR) have not yet been described fully. It is not known whether central nervous system (CNS) involvement and endocrine disorders are the extra-autonomic features of autoimmune autonomic ganglionopathy (AAG), or whether it is related to circulating anti-gAChR antibodies (Abs). The present study prospectively identified 123 Abs-positive AAG patients in Japan and collated their clinical features, investigations, and immunotherapy responses. Luciferase immunoprecipitation systems were used to detect anti-α3 and -ß4 gAChR Abs. A gradual mode of onset was more common among the 123 seropositive AAG patients examined. Patients with AAG demonstrated widespread autonomic dysfunction. In particular, orthostatic hypotension and lower gastrointestinal tract dysfunction were frequently observed. Approximately 80% of patients with seropositive AAG exhibited extra-autonomic manifestations, including CNS involvement, endocrine disorders, other autoimmune disease, and tumors. Additionally, the majority exhibited a marked improvement in clinical status and the levels of anti-gAChR Abs with immunotherapy. CNS involvement and endocrine disorders were frequent among the seropositive patients with AAG, indicating that seropositivity for AAG may be associated with underlying conditions such as autoimmune diseases or tumors.

Clinical Problem Solving: A Tobacco Merchant Who Can't Spit.

BACKGROUND: A 47 year old man presented with a combination of dry mouth and lightheadedness while standing. His medical background was unremarkable except for cigarette smoking and hyperlipidemia. Sjögren's syndrome was ruled out, and he was referred for evaluation of orthostatic hypotension, which by then included syncopal episodes and injuries. Additional symptoms included dry eyes, constipation, reduced sweating, and erectile dysfunction. After excluding medications and structural cardiac abnormalities as causes of orthostatic hypotension, a clinical autonomic evaluation was performed. The pattern of beat-to-beat blood pressure associated with performance of the Valsalva maneuver, and a low plasma norepinephrine level that did not increase in response to standing, established that the orthostatic hypotension was neurogenic. Treatment with an alpha-adrenoceptor agonist and fludrocortisone yielded partial improvement. After systemic diseases involving autonomic failure were excluded, cardiac sympathetic neuroimaging was performed by 123I-metaliodobenzylguanidine (MIBG) scanning. The normal uptake seen in the heart indicated intact post ganglionic sympathetic innervation. There were no signs of central neurodegeneration or peripheral neuropathy. Because of symptoms and signs of both parasympathetic and sympathetic failure without denervation, an autonomic ganglionopathy was considered. A high titer of antibody to the neuronal nicotinic receptor, which mediates ganglionic neurotransmission, was obtained. The diagnosis of autoimmune autonomic ganglionopathy (AAG) was made, and the management strategy shifted to first lowering the antibody burden by plasma exchanges and then instituting chronic anti-autoimmune treatment with rituximab and a low dose of cortiosteroid. The patient showed remarkable improvement.

[The interface between the immune system and autonomic nervous system].

  The nervous system and the immune system are two major systems in human body. Although it was revealed these two systems correlated, the control of immune cell dynamics by the nervous system has come to draw a lot of attention at the present time. Recent advances in basic and preclinical science reveal that reflex neural circuits inhibit the production of cytokines and inflammation in several animal models. One well-characterized cytokine-inhibiting mechanism, termed the "inflammatory reflex", is dependent upon vagus nerve stimulation that inhibits cytokine production and attenuates the inflammation. And the mechanism for controlling lymphocyte trafficking becomes clear, and molecular basis of immune regulation by the nervous system was reported. On the other hand, the nervous system is protected from the invasion of harmful agents by the barrier. However, there are neuroimmunological disorders, which is associated with autoimmunity, tumor immunity, and infection immunity. Autoimmune autonomic ganglionopathy (AAG) is an acquired immune-mediated disorder that leads to widespread autonomic manifestations, in which autoantibodies to ganglionic nicotinic acetylcholine receptors play a central role. Previously, we elucidated the prevalence of extra-autonomic manifestations in patients with AAG. It is necessary to establish the new systems for the detection of autoantibodies to other subunits of acetylcholine receptor.

Case of autoimmune autonomic ganglionopathy manifesting anhidrosis.

Autoimmune autonomic ganglionopathy (AAG), clinically characterized by gastrointestinal dysmotility, orthostatic hypotension and tonic pupils, is an idiopathic acquired disorder of the autonomic nervous system elicited by antibodies against ganglionic acetylcholine receptor (gAChR). We encountered a 60-year-old man who presented with severe anhidrosis, difficulty in thermoregulation, orthostatic hypotension, gastrointestinal dysmotility, tonic pupils and ptosis. Histologically, an anhidrotic skin sample was normal. Routine laboratory examinations of blood, urine and cerebrospinal fluid returned no abnormal findings. Serological examination revealed antibodies against α3 and ß4 subunits of gAChR. The diagnosis was AAG. As sudomotor dysfunction reflects ganglionic neuropathy in AAG, we concluded that his anhidrosis was attributable to AAG. Anhidrosis is an important clue for the diagnosis of AAG, a rare neurological disorder.

Long-term cardiovascular autonomic and clinical changes after immunoglobulin G immunoadsorption therapy in autoimmune autonomic ganglionopathy.

: A 63-year-old male was diagnosed with autoimmune autonomic ganglionopathy based on the finding of plasma antibodies to the nicotinic acetylcholine receptor (nAChR) of autonomic ganglia. He complained of mouth and eye dryness, dysphagia, severe constipation, erectile dysfunction, urgency, frequent urination, habitual orthostatic syncope and presyncope. A remarkable symptomatic orthostatic hypotension without changes in heart rate was present. We here describe the 3-year time course of the changes in spectral indices of cardiovascular autonomic control LF/HF and LFSAP, dysautonomia symptoms intensity and anti-nAChR antibodies following repetitive selective immunoadsorptions. During the follow-up, the reduction of anti-nAChR antibodies produced by immunoadsorption was associated with a diminished orthostatic hypotension, a restored capability to increase LF/HF, LFSAP and norepinephrine in upright position, a decline in the intensity of autonomic symptoms and an improvement of life quality. Spectral parameters LF/HF and LFSAP may represent noninvasive, low-cost biomarkers suitable for autoimmune autonomic ganglionopathy patients' clinical follow-up.