Individual Restriction Of Fine Specificity Variability In Anti-GM1 IgG Antibodies Associated With Guillain-Barré Syndrome

Characteristics, treatments, and prognosis of a critical illness polyneuromyopathy patient with positive anti-GM1 after severe traumatic brain injury: A case report

To investigate the clinical features, treatment and prognosis of critical illness polyneuromyopathy (CIPNM) in patients with severe traumatic brain injury (sTBI) who had positive anti-ganglioside GM1 (anti-GM1) antibody IgG. A case of CIPNM with positive anti-GM1 antibody IgG was retrospectively analysed and followed-up for 30 months. After 1 week of treatment with large dose of short-term glucocorticoid and human immunoglobulin, the muscle strength of both lower extremities was restored to grade 1. Three months later, the muscle strength and muscle tension of the patient's limbs returned to normal except for grade 3 of bilateral dorsal extensor muscle strength. In addition, the patient can walk alone with a waddling gait. After 30 months, there was no recurrence. The application of large dose of short-term glucocorticoid and human immunoglobulin to CIPNM that are positive for anti-GM1 antibodies may be an effective treatment.

Neurological disorders-associated anti-glycosphingolipid IgG-antibodies display differentially restricted IgG subclass distribution

Antibodies against several self-glycans on glycosphingolipids are frequently detected in different neurological disorders. Their pathogenic role is profusely documented, but the keys for their origin remain elusive. Additionally, antibodies recognizing non-self glycans appear in normal human serum during immune response to bacteria. Using HPTLC-immunostaining we aimed to characterize IgM and IgG subclass antibody responses against glycosphingolipids carrying self glycans (GM1/GM2/GM3/GD1a/GD1b/GD3/GT1b/GQ1b) and non-self glycans (Forssman/GA1/“A” blood group/Nt7) in sera from 27 randomly selected neurological disorder patients presenting IgG reactivity towards any of these antigens. Presence of IgG2 (p = 0.0001) and IgG1 (p = 0.0078) was more frequent for IgG antibodies against non-self glycans, along with less restricted antibody response (two or more simultaneous IgG subclasses). Contrariwise, IgG subclass distribution against self glycans showed clear dominance for IgG3 presence (p = 0.0017) and more restricted IgG-subclass distributions (i.e. a single IgG subclass, p = 0.0133). Interestingly, anti-self glycan IgG antibodies with simultaneous IgM presence had higher proportion of IgG2 (p = 0.0295). IgG subclass frequencies were skewed towards IgG1 (p = 0.0266) for “anti-self glycan A” subgroup (GM2/GM1/GD1b) and to IgG3 (p = 0.0007) for “anti-self glycan B” subgroup (GM3/GD1a/GD3/GT1b/GQ1b). Variations in players and/or antigenic presentation pathways supporting isotype (M-G) and IgG-subclass pattern differences in the humoral immune response against glycosphingolipids carrying non-self versus self-glycans are discussed.

Most of anti-glycolipid IgG-antibodies associated to neurological disorders occur without their IgM counterpart

Background

Different neurological disorders frequently display antibodies against several self-glycans. Increasing evidence supports their pathogenic role; however, far less is known about their origin. Meanwhile, antibodies recognizing non-self glycans appear in normal human serum during immune response to bacteria.

Methods

Using high performance thin layer chromatography-immunostaining, we comparatively evaluated humoral immune response (IgG and IgM immunoreactivity) against glycolipids carrying self-glycans (GM3/GM2/GM1/GD1a/GD1b/GD3/GT1b/GQ1b) and non-self glycans (Forssman/GA1/“A” blood group/Nt7) in sera from 383 patients with neurological disorders along with 87 healthy controls.

Results

In contrast to no healthy controls having anti-self glycan IgG antibodies, one-fifth of patients’ sera had anti-self glycan IgG antibodies: remarkably, 60% of these occurred without IgM antibodies of the same specificity. Contrary to this unusual fact (anti-self glycan IgG occurrence without simultaneous presence of IgM having the same specificity ~ IgG/IgM discordance), all IgG antibodies against non-self glycans occurred simultaneously with their IgM antibody counterpart (i.e. 0% discordance). When analyzed closer, the IgG/IgM discordance frequency for anti-self glycans exhibited a dual trend: below 40% for IgG antibodies against GM2, GM1 and GD1b, and greater than 53% for IgG antibodies against the remaining self glycans. Interestingly, this discordance behavior was common to several different neurological disorders.

Conclusions

Classic immunology principles indicate this anti-self glycan IgG/IgM discordance should not occur in an antibody response; its unusual presence is discussed within the “binding site drift hypothesis” context, where anti-self glycan IgG antibodies could originate from pre-existing IgG recognizing structurally-related non-self glycans.

Electronic supplementary material

The online version of this article (10.1186/s12929-019-0562-5) contains supplementary material, which is available to authorized users.

Antigenic Targets of Patient and Maternal Autoantibodies in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder whose behavioral symptoms become apparent in early childhood. The underlying pathophysiological mechanisms are only partially understood and the clinical manifestations are heterogeneous in nature, which poses a major challenge for diagnosis, prognosis and intervention. In the last years, an important role of a dysregulated immune system in ASD has emerged, but the mechanisms connecting this to a disruption of brain development are still largely unknown. Although ASD is not considered as a typical autoimmune disease, self-reactive antibodies or autoantibodies against a wide variety of targets have been found in a subset of ASD patients. In addition, autoantibodies reactive to fetal brain proteins have also been described in the prenatal stage of neurodevelopment, where they can be transferred from the mother to the fetus by transplacental transport. In this review, we give an extensive overview of the antibodies described in ASD according to their target antigens, their different origins, and timing of exposure during neurodevelopment.

Whole Genome Sequencing and Multiplex qPCR Methods to Identify Campylobacter jejuni Encoding cst-II or cst-III Sialyltransferase

Campylobacter jejuni causes more than 2 million cases of gastroenteritis annually in the United States, and is also linked to the autoimmune sequelae Guillan-Barre syndrome (GBS). GBS often results in flaccid paralysis, as the myelin sheaths of nerve cells are degraded by the adaptive immune response. Certain strains of C. jejuni modify their lipooligosaccharide (LOS) with the addition of neuraminic acid, resulting in LOS moieties that are structurally similar to gangliosides present on nerve cells. This can trigger GBS in a susceptible host, as antibodies generated against C. jejuni can cross-react with gangliosides, leading to demyelination of nerves and a loss of signal transduction. The goal of this study was to develop a quantitative PCR (qPCR) method and use whole genome sequencing data to detect the Campylobacter sialyltransferase (cst) genes responsible for the addition of neuraminic acid to LOS. The qPCR method was used to screen a library of 89 C. jejuni field samples collected by the Food and Drug Administration Pacific Northwest Lab (PNL) as well as clinical isolates transferred to PNL. In silico analysis was used to screen 827 C. jejuni genomes in the FDA GenomeTrakr SRA database. The results indicate that a majority of C. jejuni strains could produce LOS with ganglioside mimicry, as 43.8% of PNL isolates and 46.9% of the GenomeTrakr isolates lacked the cst genes. The methods described in this study can be used by public health laboratories to rapidly determine whether a C. jejuni isolate has the potential to induce GBS. Based on these results, a majority of C. jejuni in the PNL collection and submitted to GenomeTrakr have the potential to produce LOS that mimics human gangliosides.

Experimental Guillain-Barre syndrome induced by immunization with gangliosides: Keyhole limpet hemocyanin is required for disease triggering

An experimental model of Guillain-Barré Syndrome has been established in recent years. Rabbits develop disease upon immunization with a single dose of an emulsion containing bovine brain gangliosides, KLH and complete Freund's adjuvant. Within a period of four to ten weeks after immunization, they began to produce anti-ganglioside IgG-antibodies first, and to show clinical signs of neuropathy afterwards. In addition to gangliosides, KLH is a requirement for antibody production and disease triggering. Although KLH is commonly used as an immunological carrier protein, an anti-KLH-specific immune response was necessary for induction of both events. KLH is a glycoprotein carrying most of the immunogenicity in its glycan moiety. Between 20% to 80% of anti-ganglioside IgG-antibodies present in sick rabbit sera cross-reacted with KLH, indicating that both immune responses are related. The terminal Gal-ß(1,3)-GalNAc glycan (present in gangliosides and KLH) is proposed as "key" antigenic determinant involved in inducing the anti-ganglioside immune response. These results are discussed in the context of the "binding site drift" hypothesis.

Germinal centers and autoimmune disease in humans and mice

Antibodies are involved in the pathogenesis of many autoimmune diseases. Although the mechanisms underlying the antibody response to infection or vaccination are reasonably well understood, we still have a poor understanding of the nature of autoimmune antibody responses. The most well studied are the anti-nuclear antibody responses characteristic of systemic lupus erythematosus and studies over the past decade or so have demonstrated a critical role for signaling by TLR7 and/or TLR9 in B cells to promote these responses. These Toll-like receptors (TLRs) can promote T-cell-independent extrafollicular antibody responses with a heavy-chain class switch and a low degree of somatic mutation, but they can also strongly boost the germinal center response that gives rise to high-affinity antibodies and long-lived plasma cells. TLRs have been shown to enhance affinity maturation in germinal center responses to produce high-affinity neutralizing antibodies in several virus infection models of mice. Although more data are needed, it appears that anti-nuclear antibodies in mouse models of lupus and in lupus patients can be generated by either pathway, provided there are genetic susceptibility alleles that compromise B-cell tolerance at one or another stage. Limited data in other autoimmune diseases suggest that the germinal center response may be the predominant pathway leading to autoantibodies in those diseases. A better understanding of the mechanisms of autoantibody production may ultimately be helpful in the development of targeted therapeutics for lupus or other autoimmune diseases.

Zika virus and neurologic autoimmunity: the putative role of gangliosides

An increasing number of severe neurological complications associated with Zika virus (ZIKV), chiefly Guillain-Barré syndrome (GBS) and primary microcephaly, have led the World Health Organization to declare a global health emergency. Molecular mimicry between glycolipids and surface molecules of infectious agents explain most of the cases of GBS preceded by infection, while a direct toxicity of ZIKV on neural cells has been raised as the main mechanism by which ZIKV induces microcephaly. Gangliosides are crucial in brain development, and their expression correlates with neurogenesis, synaptogenesis, synaptic transmission, and cell proliferation. Targeting the autoimmune response to gangliosides may represent an underexploited opportunity to examine the increased incidence of neurological complications related to ZIKV infection.