Structural principles of distinct assemblies of the human α4ß2 nicotinic receptor.

Fast chemical communication in the nervous system is mediated by neurotransmitter-gated ion channels. The prototypical member of this class of cell surface receptors is the cation-selective nicotinic acetylcholine receptor. As with most ligand-gated ion channels, nicotinic receptors assemble as oligomers of subunits, usually as hetero-oligomers and often with variable stoichiometries 1 . This intrinsic heterogeneity in protein composition provides fine tunability in channel properties, which is essential to brain function, but frustrates structural and biophysical characterization. The α4ß2 subtype of the nicotinic acetylcholine receptor is the most abundant isoform in the human brain and is the principal target in nicotine addiction. This pentameric ligand-gated ion channel assembles in two stoichiometries of α- and ß-subunits (2α:3ß and 3α:2ß). Both assemblies are functional and have distinct biophysical properties, and an imbalance in the ratio of assemblies is linked to both nicotine addiction2,3 and congenital epilepsy4,5. Here we leverage cryo-electron microscopy to obtain structures of both receptor assemblies from a single sample. Antibody fragments specific to ß2 were used to 'break' symmetry during particle alignment and to obtain high-resolution reconstructions of receptors of both stoichiometries in complex with nicotine. The results reveal principles of subunit assembly and the structural basis of the distinctive biophysical and pharmacological properties of the two different stoichiometries of this receptor.

Activation of Gpr109a, receptor for niacin and the commensal metabolite butyrate, suppresses colonic inflammation and carcinogenesis.

Commensal gut microflora and dietary fiber protect against colonic inflammation and colon cancer through unknown targets. Butyrate, a bacterial product from fermentation of dietary fiber in the colon, has been implicated in this process. GPR109A (encoded by Niacr1) is a receptor for butyrate in the colon. GPR109A is also a receptor for niacin, which is also produced by gut microbiota and suppresses intestinal inflammation. Here we showed that Gpr109a signaling promoted anti-inflammatory properties in colonic macrophages and dendritic cells and enabled them to induce differentiation of Treg cells and IL-10-producing T cells. Moreover, Gpr109a was essential for butyrate-mediated induction of IL-18 in colonic epithelium. Consequently, Niacr1(-/-) mice were susceptible to development of colonic inflammation and colon cancer. Niacin, a pharmacological Gpr109a agonist, suppressed colitis and colon cancer in a Gpr109a-dependent manner. Thus, Gpr10a has an essential role in mediating the beneficial effects of gut microbiota and dietary fiber in colon.

Correlation of anti-γ/ε nicotinic acetylcholine receptor antibody levels with anti-desmoglein 1,3 antibody levels and disease severity in pemphigus vulgaris.

BACKGROUND: A role for nondesmoglein antigens in the pathogenesis of pemphigus vulgaris (PV) has been suggested in several studies. Acetylcholine receptors (AchR), are one of the most important groups of these antigens. However, the exact role of both antimuscarinic (m) and nicotinic (n) AchR antibodies (Abs) is still controversial. AIM: To evaluate anti-desmoglein (Dsg)1, Dsg 3 and anti-γ/ε nAchR Abs values in patients with PV before and 3 months after rituximab (RTX) treatment, and to assess their correlation with disease severity. METHODS: In total, 75 patients with PV (26 men, 49 women) who were planned to receive RTX were enrolled. Disease activity was assessed by using the Pemphigus Disease Area Index (PDAI). Using ELISA, anti-Dsg1,3 and anti-γ/ε nAchR Abs were determined at baseline and 3 months after RTX treatment. RESULTS: At baseline, 53.33% patients had positive values for anti-Dsg1, 89.33% for anti-Dsg3 and 13.33% for anti-γ/ε nAchR Abs. All patients with positive anti-γ/ε nAchR Abs had the mucocutaneous phenotype. PDAI, anti-Dsg1,3 and anti-γ/ε nAchR values were dramatically decreased 3 months after RTX infusion (P < 0.001). There was a significant positive correlation between disease activity and anti-γ/ε nAchR values at baseline (P = 0.04), whereas no significant correlation was observed between anti-Dsg1,3 and anti-γ/ε nAchR values at baseline and 3 months after RTX infusion. CONCLUSION: The reduction in anti-γ/ε nAchR Abs with clinical improvement in this study may suggest a synergic role for anti-γ/ε nAchR Abs with anti-Dsg1,3 Abs, or it could be an epiphenomenon.

Cholinergic anti-inflammatory pathway and connective tissue diseases.

Connective tissue diseases (CTDs) consist of an extensive range of heterogeneous medical conditions, which are caused by immune-mediated chronic inflammation and influences the various connective tissues of the body. They include rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, vasculitis, Sjögren's syndrome, Behcet's disease, and many other autoimmune CTDs. To date, several anti-inflammatory approaches have been developed to reduce the severity of inflammation or its subsequent organ manifestations. As a logical mechanism to harnesses the undesired inflammation, some studies investigated the role of the intrinsic cholinergic anti-inflammatory pathway (CAP) in the modulation of chronic inflammation. Many different experimental and clinical models have been developed to evaluate the therapeutic significance of the CAP in CTDs. On the other hand, an issue that is less emphasized in this regard is the presence of autonomic neuropathy in CTDs, which influences the efficiency of CAP in such clinical settings. This condition occurs during CTDs and is a well-known complication of patients suffering from them. The advantages and limitations of CAP in the control of inflammatory responses and its possible therapeutic benefits in the treatment of CTDs are the main subjects of the current study. Therefore, this narrative review article is provided based on the recent findings of the complicated role of CAP in CTDs which were retrieved by searching Science Direct, PubMed, Google Scholar, and Web of Science. It seems that delineating the complex influences of CAP would be of great interest in designing novel surgical or pharmacological therapeutic strategies for CTDs therapy.

Natural biased signaling of hydroxycarboxylic acid receptor 3 and G protein-coupled receptor 84.

BACKGROUND: Medium-chain fatty acids and their 3-hydroxy derivatives are metabolites endogenously produced in humans, food-derived or originating from bacteria. They activate G protein-coupled receptors, including GPR84 and HCA3, which regulate metabolism and immune functions. Although both receptors are coupled to Gi proteins, share at least one agonist and show overlapping tissue expression, GPR84 exerts pro-inflammatory effects whereas HCA3 is involved in anti-inflammatory responses. Here, we analyzed signaling kinetics of both HCA3 and GPR84, to unravel signal transduction components that may explain their physiological differences. METHODS: To study the signaling kinetics and components involved in signal transduction of both receptors we applied the label-free dynamic mass redistribution technology in combination with classical cAMP, ERK signaling and ß-arrestin-2 recruitment assays. For phenotypical analyses, we used spheroid cell culture models. RESULTS: We present strong evidence for a natural biased signaling of structurally highly similar agonists at HCA3 and GPR84. We show that HCA3 signaling and trafficking depends on dynamin-2 function. Activation of HCA3 by 3-hydroxyoctanoic acid but not 3-hydroxydecanoic acid leads to ß-arrestin-2 recruitment, which is relevant for cell-cell adhesion. GPR84 stimulation with 3-hydroxydecanoic acid causes a sustained ERK activation but activation of GPR84 is not followed by ß-arrestin-2 recruitment. CONCLUSIONS: In summary, our results highlight that biased agonism is a physiological property of HCA3 and GPR84 with relevance for innate immune functions potentially to differentiate between endogenous, non-pathogenic compounds and compounds originating from e.g. pathogenic bacteria. Video Abstract.

Coronary spastic angina after the administration of intravenous immunoglobulin in myasthenia gravis: a case report.

BACKGROUND: Myasthenia gravis (MG) is an autoimmune disease caused by antibodies that block or destroy nicotinic acetylcholine receptors at the neuromuscular junction. Most of MG patients need immunosuppression agents in addition to treatments that alleviate the symptoms. Intravenous immunoglobulin (IVIg) and plasma exchange are specific treatments given to patients with severe MG and myasthenia gravis crisis. IVIg therapy can cause an increase in serum viscosity; therefore, the risk for thromboembolic events, such as stroke, myocardial infarction, and pulmonary embolism, are reported after IVIg therapy. CASE PRESENTATION: An MG patient was treated with pyridostigmine bromide and prednisolone. The patient's symptoms worsened 26 days after the commencement of treatment and was presented with head drop and dyspnea. The patient was diagnosed with MG crisis and IVIg was initiated. However, the patient reported chest pain and dyspnea 3 days after IVIg had started. An electrocardiogram (ECG) revealed ST elevations in leads II, III, and aVF. A cardiac catheterization was performed and stenosis, obstruction, and sclerosis were ruled out. Glyceryl trinitrate relieved the patient's symptoms, suggesting coronary spastic angina (CSA). CONCLUSIONS: We report the first case of CSA after IVIg. Practitioners should be aware of the potential risks of CSA when administering IVIg for MG patients, in particular in old patients with vascular risk factors.

Incidence of AChR Ab-positive myasthenia gravis in Israel: A population-based study.

BACKGROUND: The incidence of myasthenia gravis (MG) has traditionally been low, ranging between 2-6/106 . Several recent epidemiological studies have reported a higher incidence. We, therefore, aimed to assess and characterize the incidence of MG in Israel. METHODS: We retrospectively reviewed the records of all four laboratories that performed the acetylcholine receptor antibody (AChR Ab) test in Israel between 1994 and 2013 and documented the number of newly diagnosed seropositive MG patients each year. To assure that data indeed reflect only newly diagnosed patients, patient's names and ID numbers were screened at the Hadassah medical center database since 1978, the year when the test was first performed in Israel. In order to calculate the annual incidence of the disease, the population at risk was derived from the annual publication of the Israeli Central Bureau of Statistics. RESULTS: The annual incidence of MG for this time period was 13.1/106 inhabitants. The mean incidence of MG between 1994 and 2003 was 7.695/106 /y, while the mean incidence between 2004 and 2013 was 18.49/106 (P < .0001). Mean age of diagnosis between 1994 and 2003 was 56.65 ± 0.9351, while between 2004 and 2013, it was 59.89 ± 0.5336 (P = .0012). Male to female (M:F) incidence ratio in the years 1994-2003 and 2004-2013 was 2:3.2 and 3:1.8, respectively, reflecting increased incidence among males (P < .0001). CONCLUSIONS: The incidence of MG in Israel has increased significantly during the last decade, especially among males of older age. These findings may reflect an etiological role of an environmental factor, increased awareness, and increased longevity in general.

Apical splenic nerve electrical stimulation discloses an anti-inflammatory pathway relying on adrenergic and nicotinic receptors in myeloid cells.

The autonomic nervous system innervates all lymphoid tissues including the spleen therefore providing a link between the central nervous system and the immune system. The only known mechanism of neural inhibition of inflammation in the spleen relies on the production of norepinephrine by splenic catecholaminergic fibers which binds to ß2-adrenergic receptors (ß 2-ARs) of CD4+ T cells. These CD4+ T cells trigger the release of acetylcholine that inhibits the secretion of inflammatory cytokines by macrophages through α7 nicotinic acetylcholine receptor (α7nAchRs) signaling. While the vagal anti-inflammatory pathway has been extensively studied in rodents, it remains to be determined whether it coexists with other neural pathways. Here, we have found that three nerve branches project to the spleen in mice. While two of these nerves are associated with an artery and contain catecholaminergic fibers, the third is located at the apex of the spleen and contain both catecholaminergic and cholinergic fibers. We found that electrical stimulation of the apical nerve, but not the arterial nerves, inhibited inflammation independently of lymphocytes. In striking contrast to the anti-inflammatory pathway mechanism described so far, we also found that the inhibition of inflammation by apical nerve electrical stimulation relied on signaling by both ß 2-ARs and α7nAchRs in myeloid cells, with these two signaling pathways acting in parallel. Most importantly, apical splenic nerve electrical stimulation mitigated clinical symptoms in a mouse model of rheumatoid arthritis further providing the proof-of-concept that such an approach could be beneficial in patients with Immune-mediated inflammatory diseases.

Survival and mortality of adult-onset myasthenia gravis in the population of Belgrade, Serbia.

INTRODUCTION: The objective of this study was to estimate mortality and survival in a large cohort of myasthenia gravis (MG) patients from Belgrade, Serbia, during the period 1979-2008. METHODS: Data for all patients with MG were collected from hospital records and the Belgrade MG Registry. RESULTS: Within the 30-year study period, death occurred in 107 (20%) of 562 patients with MG, with MG-related fatality below 2%. The average MG mortality rate was 1.76 per 1,000,000 population (1.26/1,000,000 women, 2.45/1,000,000 men). A statistically significant increase was recorded for the average standardized mortality rate for all patients (P < 0.01). The mean survival from disease onset was 34.3 ± 2.0 years. Significantly shorter survival was observed in men compared with women and in patients older than 50 years compared with younger ones (P < 0.01). DISCUSSION: We observed long survival and low frequency of MG-related fatalities but increasing average standardized mortality rate, most notably in older men with MG. Muscle Nerve 58: 708-712, 2018.

Mutated cancer autoantigen implicated cause of paraneoplastic myasthenia gravis.

INTRODUCTION: Antitumor immune responses are postulated to initiate paraneoplastic neurological disorders when proteins that are normally restricted to neural cells are expressed as oncoproteins. Mutated oncopeptides could bypass self-tolerant T cells to activate cytotoxic effector T lymphocytes and requisite helper T lymphocytes to stimulate autoantibody production by B lymphocytes. METHODS: We investigated muscle-type nicotinic acetylcholine receptor (AChR) antigen expression at transcriptional and protein levels in a small-cell lung cancer line (SCLC) established from a patient with AChR-immunoglobulin G (IgG)-positive myasthenia gravis. RESULTS: We identified messenger RNA transcripts encoding the 2 AChR α1-subunit isoforms and 7 alternative-splicing products, 3 of which yielded premature stop codons. Despite detecting native muscle-type AChR pentamers in the tumor, we did not identify mutant α1-peptides. However, we found α1-subunit-derived peptides bound to tumor major histocompatibility complex (MHC)1-protein. In a control SCLC from an antineuronal nuclear autoantibody, type 1 (anti-Hu)-IgG-positive patient, we identified MHC1-complexed Hu protein-derived peptides but not AChR peptides. DISCUSSION: Our findings support onconeural protein products as pertinent immunogens initiating paraneoplastic neurological autoimmunity. Muscle Nerve 58: 600-604, 2018.

Infiltration of CCR2+Ly6Chigh Proinflammatory Monocytes and Neutrophils into the Central Nervous System Is Modulated by Nicotinic Acetylcholine Receptors in a Model of Multiple Sclerosis.

Myeloid cells, including proinflammatory monocytes and neutrophils, have important roles in the pathology of multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). These cells infiltrate the CNS in the early stages of disease development and contribute to the inflammatory response that is associated with symptom severity. It is thus crucial to identify and understand new mechanisms that can regulate the CNS infiltration of proinflammatory myeloid cells. Nicotinic acetylcholine receptors (nAChRs) have been increasingly studied for their immune-regulatory properties. In this study, we assessed the ability of nicotine, an nAChR ligand, to modulate proinflammatory myeloid cell numbers within the bone marrow, spleen, blood, and CNS of EAE mice. We found that nicotine significantly inhibits the infiltration of proinflammatory monocytes and neutrophils into the CNS at time points where these cells are known to play critical roles in disease pathology. In contrast, nicotine does not affect the expansion of other monocytes. We also show that nicotine exerts these effects by acting on α7 and α9 nAChR subtypes. Finally, mRNA transcript levels for CCL2 and CXCL2, chemokines involved in the chemotaxis of proinflammatory monocytes and neutrophils, respectively, are reduced in the brain of nicotine-treated EAE mice before the massive infiltration of these cells. Taken together, our data provide evidence that nAChRs can regulate proinflammatory cell infiltration into the CNS, which could be of significant value for the treatment of neuroinflammatory disorders.

AMP010014A09 in Sus Scrofa Encodes an Analog of G Protein-Coupled Receptor 109A, Which Mediates the Anti-Inflammatory Effects of Beta-Hydroxybutyric Acid.

BACKGROUND: Hydroxy-carboxylic acid receptor 2 (HCA2, also called GPR109A) belongs to the G protein-coupled receptor (GPCR) family and is found in humans, rats, mice, hamsters and guinea pigs, but there are almost no reports of this protein in other species. In this investigation, we speculated that AMP010014A09 (AMP+) is a homologue of GPR109A in swine. METHODS: To test this hypothesis, the following experiments were designed: monocytes isolated from the peripheral blood of swine were treated with LPS after pretreating with or without ß-hydroxybutyric acid (BHBA), and the levels of pro-inflammatory cytokines and inflammatory proteins were assessed. cAMP levels induced by Forskolin in swine testicular (ST) and IPEC-J2 cells were detected with or without BHBA treatment and following silencing or stable transfection of the AMP+ gene. RESULTS: AMP+ in swine exhibited a high level of homology with HM74A in humans and PUMA-G in mice. BHBA inhibited the LPS-induced secretion of the pro-inflammatory cytokines TNF-α, IL-6 and IL-1ß and the inflammatory protein COX-2 in monocytes of swine. BHBA suppressed the Forskolin-induced cAMP level increase in ST cells, but failed to inhibit the accumulation of cAMP after the AMP+ gene was silenced with shRNA by transfecting cells with the pGPU6-GFP-Neo-AMP+-sus-392 plasmid. BHBA had no effect on cAMP levels in IPEC-J2 cells, but significantly inhibited the increase in cAMP induced by Forskolin treatment following transfection of the AMP+ gene into IPEC-J2 cells by a lentivirus vector. CONCLUSION: Our results indicated that AMP+ encodes a G protein-coupled receptor in Sus scrofa that inhibits cAMP levels and mediates anti-inflammatory effects in swine monocytes.

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.

Pharmacological Regulation of Neuropathic Pain Driven by Inflammatory Macrophages.

Neuropathic pain can have a major effect on quality of life but current therapies are often inadequate. Growing evidence suggests that neuropathic pain induced by nerve damage is caused by chronic inflammation. Upon nerve injury, damaged cells secrete pro-inflammatory molecules that activate cells in the surrounding tissue and recruit circulating leukocytes to the site of injury. Among these, the most abundant cell type is macrophages, which produce several key molecules involved in pain enhancement, including cytokines and chemokines. Given their central role in the regulation of peripheral sensitization, macrophage-derived cytokines and chemokines could be useful targets for the development of novel therapeutics. Inhibition of key pro-inflammatory cytokines and chemokines prevents neuroinflammation and neuropathic pain; moreover, recent studies have demonstrated the effectiveness of pharmacological inhibition of inflammatory (M1) macrophages. Nicotinic acetylcholine receptor ligands and T helper type 2 cytokines that reduce M1 macrophages are able to relieve neuropathic pain. Future translational studies in non-human primates will be crucial for determining the regulatory mechanisms underlying neuroinflammation-associated neuropathic pain. In turn, this knowledge will assist in the development of novel pharmacotherapies targeting macrophage-driven neuroinflammation for the treatment of intractable neuropathic pain.

Autoimmune channelopathies in paraneoplastic neurological syndromes.

Paraneoplastic neurological syndromes and autoimmune encephalitides are immune neurological disorders occurring or not in association with a cancer. They are thought to be due to an autoimmune reaction against neuronal antigens ectopically expressed by the underlying tumour or by cross-reaction with an unknown infectious agent. In some instances, paraneoplastic neurological syndromes and autoimmune encephalitides are related to an antibody-induced dysfunction of ion channels, a situation that can be labelled as autoimmune channelopathies. Such functional alterations of ion channels are caused by the specific fixation of an autoantibody upon its target, implying that autoimmune channelopathies are usually highly responsive to immuno-modulatory treatments. Over the recent years, numerous autoantibodies corresponding to various neurological syndromes have been discovered and their mechanisms of action partially deciphered. Autoantibodies in neurological autoimmune channelopathies may target either directly ion channels or proteins associated to ion channels and induce channel dysfunction by various mechanisms generally leading to the reduction of synaptic expression of the considered channel. The discovery of those mechanisms of action has provided insights on the regulation of the synaptic expression of the altered channels as well as the putative roles of some of their functional subdomains. Interestingly, patients' autoantibodies themselves can be used as specific tools in order to study the functions of ion channels. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

Altered expression of autoimmune regulator in infant down syndrome thymus, a possible contributor to an autoimmune phenotype.

Down syndrome (DS), caused by trisomy of chromosome 21, is associated with immunological dysfunctions such as increased frequency of infections and autoimmune diseases. Patients with DS share clinical features, such as autoimmune manifestations and specific autoantibodies, with patients affected by autoimmune polyendocrine syndrome type 1. Autoimmune polyendocrine syndrome type 1 is caused by mutations in the autoimmune regulator (AIRE) gene, located on chromosome 21, which regulates the expression of tissue-restricted Ags (TRAs) in thymic epithelial cells. We investigated the expression of AIRE and TRAs in DS and control thymic tissue using quantitative PCR. AIRE mRNA levels were elevated in thymic tissue from DS patients, and trends toward increased expression of the AIRE-controlled genes INSULIN and CHRNA1 were found. Immunohistochemical stainings showed altered cell composition and architecture of the thymic medulla in DS individuals with increased frequencies of AIRE-positive medullary epithelial cells and CD11c-positive dendritic cells as well as enlarged Hassall's corpuscles. In addition, we evaluated the proteomic profile of thymic exosomes in DS individuals and controls. DS exosomes carried a broader protein pool and also a larger pool of unique TRAs compared with control exosomes. In conclusion, the increased AIRE gene dose in DS could contribute to an autoimmune phenotype through multiple AIRE-mediated effects on homeostasis and function of thymic epithelial cells that affect thymic selection processes.

Myeloid-derived suppressor cells as a potential therapy for experimental autoimmune myasthenia gravis.

We recently demonstrated that hepatic stellate cells induce the differentiation of myeloid-derived suppressor cells (MDSCs) from myeloid progenitors. In this study, we found that adoptive transfer of these MDSCs effectively reversed disease progression in experimental autoimmune myasthenia gravis (EAMG), a T cell-dependent and B cell-mediated model for myasthenia gravis. In addition to ameliorated disease severity, MDSC-treated EAMG mice showed suppressed acetylcholine receptor (AChR)-specific T cell responses, decreased levels of serum anti-AChR IgGs, and reduced complement activation at the neuromuscular junctions. Incubating MDSCs with B cells activated by anti-IgM or anti-CD40 Abs inhibited the proliferation of these in vitro-activated B cells. Administering MDSCs into mice immunized with a T cell-independent Ag inhibited the Ag-specific Ab production in vivo. MDSCs directly inhibit B cells through multiple mechanisms, including PGE2, inducible NO synthase, and arginase. Interestingly, MDSC treatment in EAMG mice does not appear to significantly inhibit their immune response to a nonrelevant Ag, OVA. These results demonstrated that hepatic stellate cell-induced MDSCs concurrently suppress both T and B cell autoimmunity, leading to effective treatment of established EAMG, and that the MDSCs inhibit AChR-specific immune responses at least partially in an Ag-specific manner. These data suggest that MDSCs could be further developed as a novel approach to treating myasthenia gravis and, even more broadly, other diseases in which T and B cells are involved in pathogenesis.

Complex regional pain syndrome and dysautonomia in a 14-year-old girl responsive to therapeutic plasma exchange.

Reflex sympathetic dystrophy, also known as complex regional pain syndrome (CRPS), has recently been shown to be associated with autoantibodies against ß2-adrenergic and muscarinic M2 receptors. In addition to pain and sudomotor/vasomotor symptoms, dysautonomia is also observed in a subset of CRPS patients. Despite its severity, there are few effective therapies for CRPS described to date. We report a case of a 14-year-old girl with CRPS of her right leg and dysautonomia (gastroparesis, postural tachycardia) refractory to multiple therapies, successfully treated with therapeutic plasma exchange (TPE) with albumin replacement. The patient, who has serum anti ß2-adrenergic and muscarinic M2 receptor autoantibodies in addition to nicotinic acetylcholine receptor ganglionic autoantibodies, underwent an initial course of five TPEs over a 2-week period. She demonstrated a clinical response to TPE as manifested by a rapid improvement in her fatigue and gastroparesis, with a gradual yet significant improvement in her leg pain and sudomotor/vasomotor flares. Following the loading procedures, the patient was treated with rituximab. She continues to require periodic TPE to maintain a remission, with additional immunosuppression being considered long term. Although further studies are needed, TPE (in combination with immunosuppression) may be an appropriate therapy for CRPS patients with detectable autoantibodies, as it is for better characterized diseases with autoantibodies against neuronal surface receptors such as myasthenia gravis or Lambert Eaton myasthenic syndrome. J. Clin. Apheresis 31:368-374, 2016. © 2015 Wiley Periodicals, Inc.

Cholinergic Pathway Suppresses Pulmonary Innate Immunity Facilitating Pneumonia After Stroke.

BACKGROUND AND PURPOSE: Temporary immunosuppression has been identified as a major risk factor for the development of pneumonia after acute central nervous system injury. Although overactivation of the sympathetic nervous system was previously shown to mediate suppression of systemic cellular immune responses after stroke, the role of the parasympathetic cholinergic anti-inflammatory pathway in the antibacterial defense in lung remains largely elusive. METHODS: The middle cerebral artery occlusion model in mice was used to examine the influence of the parasympathetic nervous system on poststroke immunosuppression. We used heart rate variability measurement by telemetry, vagotomy, α7 nicotinic acetylcholine receptor-deficient mice, and parasympathomimetics (nicotine, PNU282987) to measure and modulate parasympathetic activity. RESULTS: Here, we demonstrate a rapidly increased parasympathetic activity in mice after experimental stroke. Inhibition of cholinergic signaling by either vagotomy or by using α7 nicotinic acetylcholine receptor-deficient mice reversed pulmonary immune hyporesponsiveness and prevented pneumonia after stroke. In vivo and ex vivo studies on the role of α7 nicotinic acetylcholine receptor on different lung cells using bone marrow chimeric mice and isolated primary cells indicated that not only macrophages but also alveolar epithelial cells are a major cellular target of cholinergic anti-inflammatory signaling in the lung. CONCLUSIONS: Thus, cholinergic pathways play a pivotal role in the development of pulmonary infections after acute central nervous system injury.

Clinical experience of seropositive ganglionic acetylcholine receptor antibody in a tertiary neurology referral center.

INTRODUCTION: Antibody against the acetylcholine receptor of autonomic ganglia (gAChR-Ab) is implicated in the pathogenesis of autoimmune autonomic ganglionopathy (AAG) and several other disorders. METHODS: This study was a retrospective evaluation of 95 patients positive for gAChR-Ab. RESULTS: Twenty-one (22%) patients had AAG, with a greater median gAChR-Ab level (0.21 nmol/L) and higher percentage (57%) of antibody levels >0.20 nmol/L when compared with the remaining 74 patients without autonomic manifestations (non-AAG group, 0.10 nmol/L and 15%, respectively). Only 2 new cases of malignancy were diagnosed after gAChR-Ab detection. The non-AAG group was associated with high frequencies of neurological and non-neurological autoimmunity, but also included 23 (31%) patients with mostly degenerative disorders. CONCLUSION: Detection of gAChR-Ab, especially at a higher level, is helpful for the diagnosis of AAG in patients with corresponding autonomic symptoms. However, its value is limited for predicting cancer risk and for diagnosis and management of patients without autonomic symptoms.