Antibodies to muscle and ganglionic acetylcholine receptors (AchR) in celiac disease

Positive acetylcholine receptor antibody in non-myasthenic patients

INTRODUCTION/AIMS

This study aims to investigate the frequency of acetylcholine receptor (AChR) binding antibody positivity via neuroautoimmunity panel testing, and describe its occurrence in a group of non-myasthenic disorders.

METHODS

This is a retrospective analysis of patients who underwent neuroautoimmunity antibody panel testing from 2010 to 2018 at Cleveland Clinic.

RESULTS

A total of 10,855 patients received neuroautoimmunity antibody panel testing, and 224 (2.1%) patients were positive for AChR binding antibody. Fifty-eight patients with known myasthenia gravis (MG) diagnosis and 11 patients with incomplete follow-up were excluded. Among the remaining 155 patients, 30 had newly diagnosed MG and 125 were non-myasthenic. In 35 patients, MG was within the initial differential diagnosis based on the clinical presentation. In contrast to non-myasthenic patients, myasthenic patients were more likely to have an initial clinical presentation raising suspicion for MG (73.3% versus 10.4%, p<0.001), higher mean AChR binding antibody titer (8.2 ±15.6 versus 0.4±1.6 nM, p=0.011) and higher frequency of abnormal AChR modulating antibody (89.3% versus 23.9%, p<0.001). A combination of AChR binding antibody of >0.5 nM and modulating antibody of >20% in patients with a clinical suspicion of MG is virtually diagnostic of MG. A total of 31 (24.8%) non-myasthenic patients carried coexisting autoimmune conditions.

DISCUSSION

Elevated titers of AChR binding antibody can be found frequently in non-myasthenic patients. Combined analysis of clinical presentation, AChR binding antibody titer and AChR modulating antibody results can be helpful in confirming an MG diagnosis. This article is protected by copyright. All rights reserved.

Autoimmune autonomic ganglionopathy: Ganglionic acetylcholine receptor autoantibodies

Autoimmune Autonomic Ganglionopathy (AAG) is a rare immune-mediated disease of the autonomic nervous system. The incidence of AAG is unknown and diagnosis is often difficult due to the multicompartmental nature of the autonomic nervous system - sympathetic, parasympathetic and enteric components - with variable severity and number of components affected. Diagnostic confidence is increased when ganglionic acetylcholine receptor (gnACHR) autoantibodies are detected. Three gnACHR autoantibody diagnostic assays have been described (two binding assays, one receptor immunomodulation assay), but cross-validation between assays is limited. The prevalence of gnACHR autoantibodies in AAG is not known, with application of different clinical and laboratory criteria in the few studies of AAG cohorts and large retrospective laboratory studies of positive gnACHR autoantibodies lacking adequate clinical characterisation. Furthermore, the rate of unexpected gnACHR autoantibody positivity in conditions without overt autonomic dysfunction (false positive results) adds to the complexity of their interpretation. We review the pathophysiology of gnACHR autoantibodies and assays for their detection, with immunomodulation and high titer radioimmunoprecipitation results likely offering better AAG disease identification.

Gastrointestinal dysfunction in neuroinflammatory diseases: Multiple sclerosis, neuromyelitis optica, acute autonomic ganglionopathy and related conditions

Disorders of the nervous system can produce a variety of gastrointestinal (GI) dysfunctions. Among these, lesions in various brain structures can cause appetite loss (hypothalamus), decreased peristalsis (presumably the basal ganglia, pontine defecation center/Barrington's nucleus), decreased abdominal strain (presumably parabrachial nucleus/Kolliker-Fuse nucleus) and hiccupping and vomiting (area postrema/dorsal vagal complex). In addition, decreased peristalsis with/without loss of bowel sensation can be caused by lesions of the spinal long tracts and the intermediolateral nucleus or of the peripheral nerves and myenteric plexus. Recently, neural diseases of inflammatory etiology, particularly those affecting the PNS, are being recognized to contribute to GI dysfunction. Here, we review neuroinflammatory diseases that potentially cause GI dysfunction. Among such CNS diseases are multiple sclerosis, neuromyelitis optica spectrum disorder, myelin oligodendrocyte glycoprotein associated disorder, and autoimmune encephalitis. Peripheral nervous system diseases impacting the gut include Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy, acute sensory-autonomic neuropathy/acute motor-sensory-autonomic neuropathy, acute autonomic ganglionopathy, myasthenia gravis and acute autonomic neuropathy with paraneoplastic syndrome. Finally, collagen diseases, such as Sjogren syndrome and systemic sclerosis, and celiac disease affect both CNS and PNS. These neuro-associated GI dysfunctions may predate or present concurrently with brain, spinal cord or peripheral nerve dysfunction. Such patients may visit gastroenterologists or physicians first, before the neurological diagnosis is made. Therefore, awareness of these phenomena among general practitioners and collaboration between gastroenterologists and neurologists are highly recommended in order for their early diagnosis and optimal management, as well as for systematic documentation of their presentations and treatment.

Neurological Manifestations of Neuropathy and Ataxia in Celiac Disease: A Systematic Review

Celiac disease (CD) is an immune-mediated gastrointestinal disorder driven by innate and adaptive immune responses to gluten. Patients with CD are at an increased risk of several neurological manifestations, frequently peripheral neuropathy and gluten ataxia. A systematic literature review of the most commonly reported neurological manifestations (neuropathy and ataxia) associated with CD was performed. MEDLINE, Embase, the Cochrane Library, and conference proceedings were systematically searched from January 2007 through September 2018. Included studies evaluated patients with CD with at least one neurological manifestation of interest and reported prevalence, and/or incidence, and/or clinical outcomes. Sixteen studies were included describing the risk of gluten neuropathy and/or gluten ataxia in patients with CD. Gluten neuropathy was a neurological manifestation in CD (up to 39%) in 13 studies. Nine studies reported a lower risk and/or prevalence of gluten ataxia with a range of 0%⁻6%. Adherence to a gluten-free diet appeared to improve symptoms of both neuropathy and ataxia. The prevalence of gluten neuropathy and gluten ataxia in patients with CD varied in reported studies, but the increased risk supports the need for physicians to consider CD in patients with ataxia and neurological manifestations of unknown etiology.

Celiac disease and risk of myasthenia gravis – nationwide population-based study

Background

Case reports suggest there may be an association between celiac disease (CD) and myasthenia gravis (MG).

Methods

We identified 29,086 individuals with CD in Sweden from 1969 to 2008. We compared these individuals with 144,480 matched controls. Hazard ratios (HRs) for future MG (identified through ICD codes) were estimated using Cox regression.

Results

During 326,376 person-years of follow-up in CD patients, there were 7 MG cases (21/million person-years) compared to 22 MG cases in controls during 1,642,273 years of follow-up (14/million person-years) corresponding to a HR of 1.48 (95% CI = 0.64–3.41). HRs did not differ when stratifying for age, sex or calendar period. HRs were highest in the first year after follow-up, though insignificant. Individuals with CD were at no increased risk of MG more than 5 years after CD diagnosis (HR = 0.70; 95% CI = 0.16–3.09).

Conclusion

This study found no increased risk of MG in patients with CD.

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.

Rare association of celiac disease with myasthenia gravis in a patient with other immune disorders: a case report

BACKGROUND

Celiac disease is described in association with several autoimmune diseases, but rarely with myasthenia gravis.

CASE REPORT

We describe the case of a 31-year-old white woman with celiac disease who presented manifestations related to a hyperactive immune system, including macroamylasemia, false-positive anti-HCV, positive antinuclear antibody, and Raynaud's phenomenon. The introduction of a gluten-free diet (GFD) resolved these features, but myasthenia gravis (MG) symptoms unexpectedly occurred on that occasion.

DISCUSSION

The role of a GFD in the course of autoimmune diseases has been studied and improvement has been reported in many diseases. However, there is no consensus in the literature regarding the course of neurological disorders associated with celiac disease. In the present case, a GFD did not prevent the appearance of symptoms related to myasthenia gravis. There are few reports on the association of celiac disease with myasthenia gravis and therefore little is known about the course and time of onset of myasthenia in celiac patients. The present case increases the knowledge about this unusual autoimmune neurological disease associated with celiac disease.

Mosquitocidal properties of IgG targeting the glutamate-gated chloride channel in three mosquito disease vectors (Diptera: Culicidae)

The glutamate-gated chloride channel (GluCl) is a highly sensitive insecticide target of the avermectin class of insecticides. As an alternative to using chemical insecticides to kill mosquitoes, we tested the effects of purified immunoglobulin G (IgG) targeting the extracellular domain of GluCl from Anopheles gambiae (AgGluCl) on the survivorship of three key mosquito disease vectors: Anopheles gambiae s.s., Aedes aegypti and Culex tarsalis. When administered through a single blood meal, anti-AgGluCl IgG reduced the survivorship of A. gambiae in a dose-dependent manner (LC50: 2.82 mg ml(-1), range 2.68-2.96 mg ml(-1)) but not A. aegypti or C. tarsalis. We previously demonstrated that AgGluCl is only located in tissues of the head and thorax of A. gambiae. To verify that AgGluCl IgG is affecting target antigens found outside the midgut, we injected it directly into the hemocoel via intrathoracic injection. A single, physiologically relevant concentration of anti-AgGluCl IgG injected into the hemocoel equally reduced mosquito survivorship of all three species. To test whether anti-AgGluCl IgG was entering the hemocoel of each of these mosquitoes, we fed mosquitoes a blood meal containing anti-AgGluCl IgG and subsequently extracted their hemolymph. We only detected IgG in the hemolymph of A. gambiae, suggesting that resistance of A. aegypti and C. tarsalis to anti-AgGluCl IgG found in blood meals is due to deficient IgG translocation across the midgut. We predicted that anti-AgGluCl IgG's mode of action is by antagonizing GluCl activity. To test this hypothesis, we fed A. gambiae blood meals containing anti-AgGluCl IgG and the GluCl agonist ivermectin (IVM). Anti-AgGluCl IgG attenuated the mosquitocidal effects of IVM, suggesting that anti-AgGluCl IgG antagonizes IVM-induced activation of GluCl. Lastly, we stained adult, female A. aegypti and C. tarsalis for GluCl expression. Neuronal GluCl expression in these mosquitoes was similar to previously reported A. gambiae GluCl expression; however, we also discovered GluCl staining on the basolateral surface of their midgut epithelial cells, suggesting important physiological differences in Culicine and Anopheline mosquitoes.

Celiac disease as an autoimmune condition

Autoimmune diseases have become a major medical problem of recent years. Celiac disease is an autoimmune disease model. The aim of our study was to follow the changes in the clinical autoimmunity picture of the celiac disease from recent years. The study of autoimmunity in celiac disease has focused on associated diseases with the aforementioned disease: type 1 diabetes mellitus, thyroid autoimmunity disease, Graves’ disease, Hashimoto's disease, systemic lupus erythematosus, systemic sclerosis, spondyloarthritis, hyperprolactinemia, Turner syndrome, Addison's disease, sensory neuronopathies. Immune reactivity to tissue transglutaminase targeted autoantibodies and other autoantigens, including transglutaminase 3, actin, ganglioside, collagen, calreticulin or zonulin which have been reported in the celiac disease. New research directions given by celiac disease autoimmunity, interleukin 1, interleukin 2, protein tyrosine phosphatase non-receptor type 22, CD4+CD25+ T lymphocytes, cytotoxic T-lymphocyte antigen 4, infection with Necator americanus and definitive identification of pathogenic T cell epitopes, seem to provide a solution in celiac disease treatment.

The neurologic significance of celiac disease biomarkers

OBJECTIVE

To report neurologic phenotypes and their etiologies determined among 68 patients with either (1) celiac disease (CD) or (2) no CD, but gliadin antibody positivity (2002-2012).

METHODS

Neurologic patients included both those with the CD-prerequisite major histocompatibility complex class II human leukocyte antigen (HLA)-DQ2/DQ8 haplotype, and those without. The 3 groups were as follows: group 1 (n = 44), CD or transglutaminase (Tg)-2/deamidated gliadin immunoglobulin (Ig)A/IgG detected; group 2 (n = 15), HLA-DQ2/DQ8 noncarriers, and gliadin IgA/IgG detected; and group 3 (n = 9), HLA-DQ2/DQ8 carriers, and gliadin IgA/IgG detected. Neurologic patients and 21 nonneurologic CD patients were evaluated for neural and Tg6 antibodies.

RESULTS

In group 1, 42 of 44 patients had CD. Neurologic phenotypes (cerebellar ataxia, 13; neuropathy, 11; dementia, 8; myeloneuropathy, 5; other, 7) and causes (autoimmune, 9; deficiencies of vitamin E, folate, or copper, 6; genetic, 6; toxic or metabolic, 4; unknown, 19) were diverse. In groups 2 and 3, 21 of 24 patients had cerebellar ataxia; none had CD. Causes of neurologic disorders in groups 2 and 3 were diverse (autoimmune, 4; degenerative, 4; toxic, 3; nutritional deficiency, 1; other, 2; unknown, 10). One or more neural-reactive autoantibodies were detected in 10 of 68 patients, all with autoimmune neurologic diagnoses (glutamic acid decarboxylase 65 IgG, 4; voltage-gated potassium channel complex IgG, 3; others, 5). Tg6-IgA/IgG was detected in 7 of 68 patients (cerebellar ataxia, 3; myelopathy, 2; ataxia and parkinsonism, 1; neuropathy, 1); the 2 patients with myelopathy had neurologic disorders explained by malabsorption of copper, vitamin E, and folate rather than by neurologic autoimmunity.

CONCLUSIONS

Our data support causes alternative to gluten exposure for neurologic dysfunction among most gliadin antibody-positive patients without CD. Nutritional deficiency and coexisting autoimmunity may cause neurologic dysfunction in CD.

Improvement in chronic muscle fasciculations with dietary change: a suspected case of gluten neuropathy

OBJECTIVE

The purpose of this case report is to describe a patient with chronic, multisite muscle fasciculations who presented to a chiropractic teaching clinic and was treated with dietary modifications.

CLINICAL FEATURES

A 28-year-old man had muscle fasciculations of 2 years. The fasciculations began in his eye and progressed to the lips and lower extremities. In addition, he had gastrointestinal distress and fatigue. The patient was previously diagnosed as having wheat allergy at the age of 24 but was not compliant with a gluten-free diet at that time. Food sensitivity testing revealed immunoglobulin G-based sensitivity to multiple foods, including many different grains and dairy products. The working diagnosis was gluten neuropathy.

INTERVENTION AND OUTCOME

Within 6 months of complying with dietary restrictions based on the sensitivity testing, the patient's muscle fasciculations completely resolved. The other complaints of brain fog, fatigue, and gastrointestinal distress also improved.

CONCLUSIONS

This report describes improvement in chronic, widespread muscle fasciculations and various other systemic symptoms with dietary changes. There is strong suspicion that this case represents one of gluten neuropathy, although testing for celiac disease specifically was not performed.

Association of autoimmunity to autonomic nervous structures with nerve function in patients with type 1 diabetes: a 16-year prospective study

OBJECTIVE We prospectively evaluated the association between autoimmunity to autonomic nervous structures and autonomic neuropathy in type 1 diabetes in relation to clinical variables. RESEARCH DESIGN AND METHODS A cohort of 112 patients with type 1 diabetes was prospectively followed from adolescence (T0) to approximately 4 (T4) and 16 (T16) years later. Standard cardiovascular (CV) tests and neurological examination were performed and related to the presence of circulating antibodies (Ab) to autonomic nervous structures detected at T0 and T4. Quality of life was assessed by a diabetes-specific questionnaire. RESULTS Sixty-six patients (59% of the cohort) were reexamined at T16 (age 31.4 ± 2 years; disease duration 23.4 ± 3.7 years). Nineteen had circulating Ab to autonomic structures. Prevalence of abnormal tests and autonomic symptoms were higher in Ab-positive (68 and 26%, respectively) than Ab-negative (32 and 4%) patients (P < 0.05). Among Ab-positive patients, the relative risk (RR) of having at least one altered CV test was 5.77 (95% CI 1.56-21.33), and an altered deep breathing (DB) test (<15 bpm) was 14.65 (2.48-86.46). Previous glycemic control was the only other predictor (RR 1.06 [1.002-1.13]/mmol/mol HbA1c increase). Presence of Ab carried over a 68% probability of developing an altered CV test; absence of Ab carried a 91% probability of not having an altered DB test and an 89% probability of not having an altered Valsalva ratio. Autonomic neuropathy was independently associated with worse quality of life. CONCLUSIONS Circulating Ab to autonomic structures are associated with the development of autonomic dysfunction in young diabetic patients independent of glycemic control.

Subclinical myopathy in patients affected with newly diagnosed colorectal cancer at clinical onset of disease: evidence from skeletal muscle biopsies

OBJECTIVE

To evaluate skeletal muscle biopsy from asymptomatic patients affected with newly diagnosed colorectal cancer and to identify pathological features which may be indicative of tumor-associated muscle disorders, potentially leading to cachexia.

METHODS

Patients affected with newly diagnosed colorectal cancer at clinical onset of disease underwent biopsy of the rectus abdominis muscle during elective laparoscopic tumor resection, before chemotherapeutic treatment. Morphometric analyses, ATPase histochemistry and immunohistochemical studies using antibodies directed to N-CAM and to MHC-emb, two sound makers of muscle denervation and injury-induced muscle regeneration, were performed on intraoperative muscle biopsies from ten patients. Muscle biopsies from rectus abdominis of seven subjects affected with non-neoplastic condition, which underwent laparoscopic surgery, were used as controls.

RESULTS

In patients' biopsies, we observed a surprisingly high percentage of myofibers with internalized or central nuclei compared to controls (9.15 +/- 8.9 versus 0.6 +/- 0.9, p<0.0003). In addition, in the 30% of patients, small myofibers expressing the MHC-emb have been identified (0.4 +/- 0.5 positive fibers/mm(2)), while in 50% of patients, larger fibers positive for N-CAM have also been detected (0.7 +/- 1.1 positive fibers/mm(2)), suggesting that investigated muscle biopsies exhibit other evidence of muscle fiber injury/regeneration and/or denervation. Among the 10,000 analysed myofibers in control biopsies, no MHC-emb and N-CAM-positive muscle fibers have been detected. Thus, patients affected with newly diagnosed colorectal cancer at clinical onset of disease display early signs of a subclinical myopathy.

DISCUSSION

Factors and mechanisms of this cancer-associated myopathy are yet unknown. The facts that the great majority of the abnormally nucleated myofibers are of the fast type and that regenerating myofibers are present, suggest a myogenic response to the colorectal cancer and not to the laparoscopic modalities of the biopsy harvesting. Follow-up of the patients will elucidate the clinical relevance of our observation, and further studies investigating the molecular mechanism underlying this early cancer-associated myopathy will hopefully provide some pathogenetic clues leading to the identification of potential specific targets for therapeutic intervention to prevent tumor cachexia.

Adult celiac disease with acetylcholine receptor antibody positive myasthenia gravis

Celiac disease has been associated with some autoimmune disorders. A 40-year-old competitive strongman with celiac disease responded to a gluten-free diet, but developed profound and generalized motor weakness with acetylcholine receptor antibody positive myasthenia gravis, a disorder reported to occur in about 1 in 5000. This possible relationship between myasthenia gravis and celiac disease was further explored in serological studies. Frozen stored serum samples from 23 acetylcholine receptor antibody positive myasthenia gravis patients with no intestinal symptoms were used to screen for celiac disease. Both endomysial and tissue transglutaminase antibodies were examined. One of 23 (or, about 4.3%) was positive for both IgA-endomysial and IgA tissue transglutaminase antibodies. Endoscopic studies subsequently showed duodenal mucosal scalloping and biopsies confirmed the histopathological changes of celiac disease. Celiac disease and myasthenia gravis may occur together more often than is currently appreciated. The presence of motor weakness in celiac disease may be a clue to occult myasthenia gravis, even in the absence of intestinal symptoms.