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

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.

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.