20. Immunologic neuromuscular disorders

Sodium butyrate alleviates R97-116 peptide-induced myasthenia gravis in mice by improving the gut microbiota and modulating immune response

Fermented butyrate exhibits an anti-inflammatory response to maintain immune homeostasis within the gut. However, the effect and underlying mechanism of butyrate on myasthenia gravis (MG) remain unclear. The changes in the gut microbiota and fecal contents of SCFAs in MG patients were examined. R97-116 peptide was used to induce the experimental autoimmune myasthenia gravis (EAMG) mice and sodium butyrate (NaB) was gavaged to the EAMG mice. Gut microbiota, the frequency of Th1, Th17, Treg, Tfh, and B cells, the levels of IFN-γ, IL-17 A, IL-10, IL-21, and anti-R97-116 IgG, RNA-seq of total B cells in the spleen were explored by metagenomics, flow cytometry, ELISA, and transcriptomics. A significant reduction in SCFA-producing bacteria including Butyricimonas synergistica and functional modules including butyrate synthesis/production II was observed in MG patients and fecal SCFAs detection confirmed the increase. The EAMG mice were successfully constructed and NaB supplementation has changed the composition and function of the gut microbiota. The numbers of Th1, Th17, Tfh, and B cells were significantly increased while that of Treg cells was obviously decreased in EAMG mice compared with controls. Interestingly, NaB treatment has reduced the amounts of Th17, Tfh, and B cells but increased that of Treg cells. Accordingly, the levels of IL-17 A, IL-21, and IgG were increased while IL-10 was decreased in EAMG mice. However, NaB treatment reduced IL-17 A and IL-21 but increased that of IL-10. RNA-seq of B cells has revealed 4577 deferentially expressed genes (DEGs), in which 1218 DEGs were up-regulated while 3359 DEGs were down-regulated in NaB-treated EAMG mice. GO enrichment and KEGG pathway analysis unveiled that the function of these DEGs was mainly focused on immunoglobulin production, mitochondrial respiratory chain complex, ribosome, oxidative phosphorylation, and CNS diseases including amyotrophic lateral sclerosis. We have found that butyrate was significantly reduced in MG patients and NaB gavage could evidently improve MG symptoms in EAMG mice by changing the gut microbiota, regulating the immune response, and altering the gene expression and function of B cells, suggesting NaB might be a potential immunomodulatory supplement for MG drugs.

Usefulness and Clinical Impact of Whole-Body MRI in Detecting Autoimmune Neuromuscular Disorders

Autoimmune neuromuscular diseases are a group of heterogenous pathologies secondary to the activation of the immune system that damage the structures of the peripheric nerve, the neuromuscular junction, or the skeleton muscle. The diagnosis of autoimmune neuromuscular disorders comprises a combination of data from clinical, laboratory, electromyography, imaging exam, and biopsy. Particularly, the whole-body MRI examination in the last two decades has been of great use in the assessment of neuromuscular disorders. MRI provides information about the structures involved and the status of activity of the disease. It can also be used as a biomarker, detect the pattern of specific muscle involvement, and is a useful tool for targeting the optimal muscle site for biopsy. In this work, we summarized the most used technical protocol of whole-body MRI and the role of this imaging technique in autoimmune neuromuscular disorders.

Pregnancy-Related Immune Changes and Demyelinating Diseases of the Central Nervous System

Demyelinating diseases of the central nervous system comprise a heterogeneous group of autoimmune disorders characterized by myelin loss with relative sparing of axons occurring on a background of inflammation. Some of the most common demyelinating diseases are multiple sclerosis, acute disseminated encephalomyelitis, and neuromyelitis optica spectrum disorders. Besides showing clinical, radiological, and histopathological features that complicate their diagnosis, demyelinating diseases often involve different immunological processes that produce distinct inflammatory patterns. Evidence of demyelination diseases derives mostly from animal studies of experimental autoimmune encephalomyelitis (EAE), a model that relies on direct antibody–antigen interactions induced by encephalitogenic T cells. Pregnancy is characterized by non-self-recognition, immunomodulatory changes and an altered Th1/Th2 balance, generally considered a Th2-type immunological state that protects the mother from infections. During pregnancy, the immune response of patients with autoimmune disease complicated with pregnancy is different. Immune tolerance in pregnancy may affect the course of some diseases, which may reach remission or be exacerbated. In this review, we summarize current knowledge on the immune status during pregnancy and discuss the relationship between pregnancy-related immune changes and demyelinating diseases of the central nervous system.

Perturbed Microbial Ecology in Myasthenia Gravis: Evidence from the Gut Microbiome and Fecal Metabolome

Myasthenia gravis (MG) is a devastating acquired autoimmune disease. Emerging evidence indicates that the gut microbiome plays a key role in maintaining immune system homeostasis. This work reports that MG is characterized by decreased α-phylogenetic diversity, and significantly disturbed gut microbiome and fecal metabolome. The altered gut microbial composition is associated with fecal metabolome changes, with 38.75% of altered bacterial operational taxonomic units showing significant correlations with a range of metabolite biomarkers. Some microbes are particularly linked with MG severity. Moreover, a combination of microbial makers and their correlated metabolites enable discriminating MG from healthy controls (HCs) with 100% accuracy. To investigate whether disturbed gut mcirobiome might contribute to the onset of MG, germ-free (GF) mice are initially colonized with MG microbiota (MMb) or healthy microbiota (HMb), and then immunized in a classic mouse model of MG. The MMb mice demonstrate substantially impaired locomotion ability compared with the HMb mice. This effect could be reversed by cocolonizing GF mice with both MMb and HMb. The MMb mice also exhibit similar disturbances of fecal metabolic pathways as found in MG. Together these data demonstrate disturbances in microbiome composition and activity that are likely to be relevant to the pathogenesis of MG.

Simultaneous Combined Myositis, Inflammatory Polyneuropathy, and Overlap Myasthenic Syndrome

Immune-mediated neuromuscular disorders include pathologies of the peripheral nervous system, neuromuscular junction, and muscles. If overlap syndromes (or the association of almost two autoimmune disorders) are recognized, the simultaneous occurrence of several autoimmune neuromuscular disorders is rare. We describe two patients presenting the simultaneous occurrence of inflammatory neuropathy, myositis, and myasthenia gravis (with positive acetylcholine receptor antibodies). For each patient, we carried out a pathological analysis (nerve and muscle) and an electrophysiological study (and follow-up). To our knowledge, this is the first description of such a triple immune-mediated neuromuscular syndrome. We compared our observations with a few other cases of simultaneous diagnosis of two inflammatory neuromuscular disorders.

Antibody-mediated rejection of the heart in the setting of autoimmune demyelinating polyneuropathy: a case report and review of the literature

Background. Antibody-mediated rejection (AMR) is caused by the production of donor-specific antibodies (DSA) which lead to allograft injury in part via complement activation. The inflammatory demyelinating polyneuropathies (IDP) are inflammatory disorders of the nervous system, involving both cellular and humoral immune mechanisms directed against myelin. Case Report. A 58-year-old man five years after heart transplant presented with progressive dyspnea, imbalance, dysphagia, and weakness. Nerve conduction studies and electromyogram were consistent with IDP. Plasmapheresis and high-dose steroids resulted in improvement in neurologic symptoms. Within two weeks, he was readmitted with anasarca and acute renal failure, requiring intravenous furosemide and inotropic support. Echocardiogram and right heart catheterization revealed reduced cardiac function and elevated filling pressures. DSA was positive against HLA DR53, and endomyocardial biopsy revealed grade 1R chronic inflammation, with strong capillary endothelial immunostaining for C4d. Plasmapheresis and intravenous immunoglobulin (IVIG) were initiated. His anasarca and renal failure subsequently resolved, echocardiogram showed improved function off inotropes, and anti-DR53 MFI was reduced by 57%. Conclusions. This is an example of a single immune-mediated process causing concurrent IDP and AMR. The improvement in cardiac function and neurologic symptoms with plasmapheresis, IVIG, and high-dose steroids argues for a unifying antibody-mediated mechanism.

Utilization of health promotion and wellness services among middle-aged and older adults with multiple sclerosis in the mid-west US

Routine engagement in healthy behaviors may improve quality of life in older adults with chronic disabling conditions, such as multiple sclerosis (MS). However, older adults with chronic conditions may face many barriers to engaging in healthy behaviors. Health promotion and wellness services may help older adults with chronic conditions engage in healthy behaviors. Thus, the purpose of this study was to identify factors associated with the use of and unmet needs for heath promotion services among middle-aged and older adults with MS. Data from a cross-sectional telephone survey of individuals aging with MS in the mid-west USA were used for this study (n = 1282). A multinomial regression model was used to identify variables associated with the utilization of health promotion services. A logistic regression model was used to identify variables associated with unmet needs for these services. Females (OR = 1.51; CI: 1.13, 2.00), high school graduates (OR = 1.77; CI: 1.34, 2.34) and people who reported no problems with mobility or balance (OR = 1.68; CI: 1.12, 2.51) were more likely to utilize health promotion and wellness services. Factors that increased the likelihood of reporting an unmet need for these services were being female (OR = 2.34; CI: 1.56, 3.51), greater than a high school education (OR = 1.58; CI: 1.14, 2.20), not being married (OR = 1.79; CI: 1.31, 2.43), having inadequate income (OR = 1.83; CI: 1.31, 2.56), experiencing pain (OR = 1.96; CI: 1.34, 2.87) and reporting less ability to do everyday activities now compared with 1 year ago (OR = 2.13; CI: 1.16, 3.92). To avoid widening the health-disparities gap, future research needs to explore strategies that promote utilization of health promotion services among all middle-aged and older adults with MS.

How citation distortions create unfounded authority: analysis of a citation network

OBJECTIVE

To understand belief in a specific scientific claim by studying the pattern of citations among papers stating it.

DESIGN

A complete citation network was constructed from all PubMed indexed English literature papers addressing the belief that beta amyloid, a protein accumulated in the brain in Alzheimer's disease, is produced by and injures skeletal muscle of patients with inclusion body myositis. Social network theory and graph theory were used to analyse this network.

MAIN OUTCOME MEASURES

Citation bias, amplification, and invention, and their effects on determining authority.

RESULTS

The network contained 242 papers and 675 citations addressing the belief, with 220,553 citation paths supporting it. Unfounded authority was established by citation bias against papers that refuted or weakened the belief; amplification, the marked expansion of the belief system by papers presenting no data addressing it; and forms of invention such as the conversion of hypothesis into fact through citation alone. Extension of this network into text within grants funded by the National Institutes of Health and obtained through the Freedom of Information Act showed the same phenomena present and sometimes used to justify requests for funding.

CONCLUSION

Citation is both an impartial scholarly method and a powerful form of social communication. Through distortions in its social use that include bias, amplification, and invention, citation can be used to generate information cascades resulting in unfounded authority of claims. Construction and analysis of a claim specific citation network may clarify the nature of a published belief system and expose distorted methods of social citation.

Exploring physical activity behaviour of persons with multiple sclerosis: a qualitative pilot study

PURPOSE

Identify facilitators and barriers to physical activity (PA), and explore the utility of Social Cognitive Theory (SCT) and Transactional Model of Stress and Coping (TMSC) in understanding PA behaviour among persons with multiple sclerosis (MS).

METHODS

Thirteen participants from a clinical trial were interviewed and classified as physically active, sometimes active or inactive based on the Health-Promoting Lifestyle Profile-II. Interviews were analysed using analytical induction, which consisted of coding data into pre-established categories and then exploring similarities and differences between groups. Pre-established coding categories were constructs from SCT (i.e. environment, expectations, self-efficacy and self-regulation) and TMSC (i.e. stress appraisal and coping style).

RESULTS

Inactive and active participants differed in their self-regulation skills, self-efficacy and coping styles. Common barriers to PA included symptoms and the physical and social environment. Facilitators of PA included strong self-regulation skills, confidence to overcome symptoms to engage in PA (i.e. barrier self-efficacy) and positive coping styles.

CONCLUSION

Results from this pilot study suggest that PA interventions will need to implement multiple strategies that target self-efficacy, social environment and coping styles. We found SCT and TMSC useful in understanding PA behaviour among persons with MS; however, a limitation to these theories is that they are not explicit in the relationship between health and cognitions. Future research will need to explore how to incorporate models of health and function into existing behaviour change theories.