Mechanisms of action of anti-GM1 and anti-GQ1b ganglioside antibodies in Guillain-Barré syndrome

Case Report: Plasma Biomarkers Reflect Immune Mechanisms of Guillain-Barré Syndrome

This case series reported a group of patients with Guillain–Barré syndrome (GBS) and their plasma cytokine changes before and after immunotherapy. We aimed to understand GBS's pathogenesis and pathophysiology through observing the interval differences of the representative cytokines, which were the thymus and activation regulated chemokine (TARC) for T-cell chemotaxis, CD40 ligand (CD40L) for cosimulation of B and T cells, activated complement component C5/C5a, and brain-derived neurotrophic factor (BDNF) for survival and regenerative responses to nerve injuries. The fluorescence magnetic bead-based multiplexing immunoassay simultaneously quantified the five cytokines in a single sample. From June 2018 to December 2019, we enrolled five GBS patients who had completed before–after blood cytokine measurements. One patient was diagnosed with paraneoplastic GBS and excluded from the following cytokine analysis. The BDNF level decreased consistently in all the patients and made it a potential biomarker for the acute stage of GBS. Interval changes of the other four cytokines were relatively inconsistent and possibly related to interindividual differences in the immune response to GBS triggers, types of GBS variants, and classes of antiganglioside antibodies. In summary, utilizing the multiplexing immunoassay helps in understanding the complex immune mechanisms of GBS and the variation of immune responses in GBS subtypes; this method is feasible for identifying potential biomarkers of GBS.

Sphingolipids regulate neuromuscular synapse structure and function in Drosophila

Sphingolipids are found in abundance at synapses and have been implicated in regulation of synapse structure, function, and degeneration. Their precise role in these processes, however, remains obscure. Serine Palmitoyl-transferase (SPT) is the first enzymatic step for synthesis of sphingolipids. Analysis of the Drosophila larval neuromuscular junction (NMJ) revealed mutations in the SPT enzyme subunit, lace/SPTLC2 resulted in deficits in synaptic structure and function. Although NMJ length is normal in lace mutants, the number of boutons per NMJ is reduced to ∼50% of the wild type number. Synaptic boutons in lace mutants are much larger but show little perturbation to the general ultrastructure. Electrophysiological analysis of lace mutant synapses revealed strong synaptic transmission coupled with predominance of depression over facilitation. The structural and functional phenotypes of lace mirrored aspects of Basigin (Bsg), a small Ig-domain adhesion molecule also known to regulate synaptic structure and function. Mutant combinations of lace and Bsg generated large synaptic boutons, while lace mutants showed abnormal accumulation of Bsg at synapses, suggesting that Bsg requires sphingolipid to regulate structure of the synapse. In support of this, we found Bsg to be enriched in lipid rafts. Our data points to a role for sphingolipids in the regulation and fine-tuning of synaptic structure and function while sphingolipid regulation of synaptic structure may be mediated via the activity of Bsg.

Guillain-Barré syndrome: a century of progress

In 1916, Guillain, Barré and Strohl reported on two cases of acute flaccid paralysis with high cerebrospinal fluid protein levels and normal cell counts - novel findings that identified the disease we now know as Guillain-Barré syndrome (GBS). 100 years on, we have made great progress with the clinical and pathological characterization of GBS. Early clinicopathological and animal studies indicated that GBS was an immune-mediated demyelinating disorder, and that severe GBS could result in secondary axonal injury; the current treatments of plasma exchange and intravenous immunoglobulin, which were developed in the 1980s, are based on this premise. Subsequent work has, however, shown that primary axonal injury can be the underlying disease. The association of Campylobacter jejuni strains has led to confirmation that anti-ganglioside antibodies are pathogenic and that axonal GBS involves an antibody and complement-mediated disruption of nodes of Ranvier, neuromuscular junctions and other neuronal and glial membranes. Now, ongoing clinical trials of the complement inhibitor eculizumab are the first targeted immunotherapy in GBS.

Miller Fisher syndrome presenting as palate paralysis

We report a 63-year old patient who presented to our care initially with a hypernasal voice followed by ataxia, ptosis, dysphonia, and paresthesias. The patient's history, physical examination, and additional tests led to a Miller Fisher syndrome (MFS) diagnosis. Palatal paralysis as an inaugurating manifestation of MFS is quite rare and requires special attention from neurologists and otolaryngologists. Although it may present as benign as an acute change in voice, early diagnosis and prompt management may prevent further complications.

Invited commentary: Influenza vaccine and Guillain-Barre syndrome--is there a risk?

After a new reassortant swine influenza A H1N1 virus caused outbreaks in Mexico and the United States in 2009, a vaccine was prepared from this virus to immunize the entire US population. Surveillance for Guillain-Barré syndrome (GBS) after receipt of this vaccine was carried out in 3 populations: the Vaccine Safety Datalink Project, the 10 Centers for Disease Control and Prevention Emerging Infections Program sites, and a network of large insurance companies. These studies found a small increase of approximately 1 case of GBS per million vaccinees above the baseline rate, which is similar to that observed after administration of seasonal influenza vaccines over the past several years. Enhanced surveillance for GBS was conducted in 2009-2010 because of the experience in 1976 of 362 GBS cases' occurring during the 6 weeks after influenza vaccination of 45 million persons, an 8.8-fold increase over background rates. The 1976 mass immunization had been conducted to prevent an influenza epidemic from another swine influenza A H1N1 recombinant virus. It can be concluded from these recent studies that influenza vaccination overall is of public health benefit, helping to reduce mortality and prevent the thousands of deaths that occur from annual seasonal influenza outbreaks, despite the possibility of a small increased risk of GBS associated with influenza vaccines.

Campylobacter jejuni DNA-binding protein from starved cells in Guillain-Barré syndrome patients

Campylobacter jejuni enteritis is frequently associated with an axonal form of Guillain-Barré syndrome (GBS) and C. jejuni DNA-binding protein from starved cells (C-Dps) induces paranodal myelin detachment and axonal degeneration through binding with sulfatide in vivo. Here we investigated the invasion of C-Dps into hosts with C. jejuni-related GBS. Our analyses of patient sera found that both C-Dps and anti-C-Dps antibodies were most commonly detected in sera from C. jejuni-related GBS patients (5/27, 14.8% and 15/24, 62.5%; respectively). These findings suggest that C-Dps invades the host and may potentially contribute to the peripheral nerve damage in C. jejuni-related GBS.

Multiplex suspension array for human anti-carbohydrate antibody profiling

Glycan-binding antibodies form a significant subpopulation of both natural and acquired antibodies and play an important role in various immune processes. They are for example involved in innate immune responses, cancer, autoimmune diseases, and neurological disorders. In the present study, a microsphere-based flow-cytometric immunoassay (suspension array) was applied for multiplexed detection of glycan-binding antibodies in human serum. Several approaches for immobilization of glycoconjugates onto commercially available fluorescent microspheres were compared, and as the result, the design based on coupling of end-biotinylated glycopolymers has been selected. This method requires only minute amounts of glycans, similar to a printed glycan microarray. The resulting glyco-microspheres were used for detection of IgM and IgG antibodies directed against ABO blood group antigens. The possibility of multiplexing this assay was demonstrated with mixtures of microspheres modified with six different ABO related glycans. Multiplexed detection of anti-glycan IgM and IgG correlated well with singleplex assays (Pearson's correlation coefficient r = 0.95-0.99 for sera of different blood groups). The suspension array in singleplex format for A/B trisaccharide, H(di) and Le(x) microspheres corresponded well to the standard ELISA (r > 0.94). Therefore, the described method is promising for rapid, sensitive, and reproducible detection of anti-glycan antibodies in a multiplexed format.

Synthesis of ganglioside epitopes for oligosaccharide specific immunoadsorption therapy of Guillian-Barré syndrome

Guillain-Barré syndrome is a postinfectious, autoimmune neuropathy resulting in neuromuscular paralysis. Auto-antibodies, often induced by bacterial infection, bind to human gangliosides possessing monosialoside and diasialoside epitopes and impair the function of nerve junctions, where these ganglioside structures are highly enriched. Truncated gangliosides representive of GD3, GQ1b and GM2 epitopes have been synthesized as methyl glycosides and as a glycosides of an eleven carbon tether. The synthetic oligosaccharide ligands are structural mimics of these highly complex ganglioside epitopes and via their ability to neutralize or remove auto-antibodies have the potential for therapy, either as soluble blocking ligands administered systemically, or as immuno-affinity ligands for use as extracorporeal immunoadsorbents.

Anti-ganglioside antibodies and clinical outcome of patients with Guillain-Barré Syndrome in northeast Brazil

OBJECTIVES

The goal of this study was to investigate the frequency of GM1 antibodies and to assess whether exposure to Campylobacter jejuni was associated with a distinct clinical variant of Guillain-Barré Syndrome (GBS) or disease outcome in Rio Grande do Norte, Brazil.

MATERIAL AND METHODS

Forty-one patients with a presumed diagnosis of GBS were enrolled and prospectively studied between June 1994 and November 1999.

RESULTS

Anti-GM1 was present in 51.2% (n = 21) of patients. The presence of anti-GM1 was significantly associated with acute axonal motor neuropathy when compared to acute inflammatory demyelinating polyneuropathy (P = 0.01). Patients with anti-GM1 antibodies presented distal muscle involvement and fewer sensory deficits. Age, time to nadir and ventilatory assistance were not associated with anti-GM1 antibodies. Eight out of 21 patients (32%) presented with anti-C. jejuni antibodies. Clinical features were similar for patients with GBS with positive and negative C. jejuni antibodies. Anti-GM1 antibodies were associated with C. jejuni infection (P = 0.0005). Presence of anti-GM1 and C. jejuni antibodies did not indicate a worse prognosis.

CONCLUSION

Patients with GBS and anti-GM1 antibodies had more distal muscle weakness, fewer sensory deficits, more axonal degeneration and C. jejuni infection, but these findings were not associated with a worse prognosis.

Ganglioside mimicry of Campylobacter jejuni lipopolysaccharides determines antiganglioside specificity in rabbits

The core oligosaccharides of Campylobacter jejuni lipopolysaccharides (LPS) display molecular mimicry with gangliosides. Cross-reactive anti-LPS-antiganglioside antibodies have been implicated to show a crucial role in the pathogenesis of the Guillain-Barré and Miller Fisher syndrome. The specificity of the antiganglioside response is thought to depend on the oligosaccharide structure of the ganglioside mimic. To test this hypothesis and to investigate the potential of LPS from Campylobacter strains from enteritis patients to induce an antiganglioside response, we immunized rabbits with purified LPS from eight Campylobacter jejuni reference strains with biochemically well-defined distinct ganglioside mimics and determined the presence of antiganglioside antibodies. All rabbits produced immunoglobulin G (IgM) and IgG anti-LPS antibodies, and the specificity of the cross-reactive antiganglioside response indeed corresponded with the biochemically defined mimic. Most rabbits also had antibody reactivity against additional gangliosides, and there were slight differences in the fine specificity of the antibody response between rabbits that had been immunized with LPS from the same Campylobacter strain. High anti-LPS and antiganglioside titers persisted over a 10-month period. In conclusion, the structure of the LPS only partly determines the antiganglioside specificity. Other strain-specific as well as host-related factors influence the induction and fine-specificity of the cross-reactive anti-LPS-antiganglioside response.

Involvement of the central nervous system in Miller Fisher syndrome: a case report

Miller Fisher syndrome (MFS) is characterised by ophthalmoplegia, ataxia and areflexia. Reports on cerebellar ataxia and supranuclear oculomotor derangement in MFS suggested an additional involvement of the central nervous system (CNS), resembling Bickerstaff's brainstem encephalitis (BBE). In the present report, a patient with a monophasic acute illness, early recovery and specific clinical-laboratory findings suggested both intrinsic brainstem and peripheral nerve disease (MFS and BBE). In pons and medulla oblangata, blurred to discrete T2-lesions were revealed by cranial MRI, while involvement of peripheral nerves was detected with EMG. The CSF showed no increase in protein or cell content, such as occurs in brainstem encephalitis.

Antibodies against gangliosides: a link between preceding infection and immunopathogenesis of Guillain-Barré syndrome

Autoantibodies against gangliosides GM1 and GQ1b, characteristic cell surface glycolipids of the nervous system, are present in specific clinical types of GuillainBarré syndrome (GBS). Close associations of anti-GM1 with acute motor axonal neuropathy, and of anti-GQ1b with Miller Fisher syndrome, strongly suggest that these antibodies contribute to neuropathy pathogenesis. Immune responses against gangliosides are suspected to originate as a result of molecular mimicry between gangliosides and lipopolysaccharides of Campylobacter jejuni, the most frequent infectious trigger of GBS. Thus, antibodies against gangliosides may link C. jejuni infection with the precipitation of neurological disease.

Recent studies on the roles of antiglycosphingolipids in the pathogenesis of neurological disorders

Evidence is mounting to suggest a causal role of humoral immunity arising from antiglycosphingolipid (GSL) antibodies in a variety of neurological disorders. These disorders include the demyelinating and axonal forms of Guillain-Barre syndrome, multifocal motor neuropathy, chronic inflammatory demyelinating polyradiculoneuropathy, and IgM paraproteinemia. Many claims have been made regarding other neurological disorders, which should be carefully scrutinized for their validity, based on several criteria proposed in this review. These criteria include 1) characterization of the causative antigens and immunoglobulins, 2) correlation of the pathological lesions and clinical manifestation of the antigens, 3) establishment of animal models using pure GSLs as the antigens, 4) immunopathogenic mechanisms of the neurodenerative process, 5) mechanisms for the malfunctioning of blood-nerve barrier and the ensuing leakage of circulating antibodies into peripheral nerve parenchyma, and 6) the roles of anti-GSL antibodies that may cause humorally mediated nerve dysfunction and injury as well as interference with ion channel function at the node of Ranvier, where carbohydrate epitopes are located. Finally, the origin of the anti-GSL antibodies is discussed in light of the recent circumstantial evidence pointing to a molecular mimicry mechanism with infectious agents. With a better understanding of the immunopathogenic mechanisms, it will then be possible to devise rational and effective diagnostic and therapeutic strategies for the treatment of these neurological disorders.

Use of peptide ligands to analyze the fine specificity of antibodies against asialo GM1

We recently described clone 10, a monoclonal Fab fragment that binds to asialo GM1 (GA1), and three mutated Abs derived from it that also bind GA1 and have a three to four times increase in avidity. We selected a phage display linear heptapeptide library with these four Abs, and an IgM mAb, 156, which binds to GM1 and GD1b, but not to GA1. Peptides with the same motif, KL/VWQXXX, were selected by clones 10 and the two heavy chain mutants 227 and 109. In contrast, the light chain mutant L3 58 selected an entirely different peptide motif, TFGLQSL. Moreover, a different motif, K/SWTNL/MPP, was selected by mAb 156. Although mAbs clone 10 and its mutants 109, 227 and L3 58 all bind only to GA1, differences in their fine specificity were revealed by binding to peptide ligands.

Pathogenic autoantibodies to neuronal proteins in neurological disorders

Autoantibodies to acetylcholine receptors and to voltage-gated calcium and potassium channels are thought to be pathogenic in three peripheral neurological disorders: myasthenia gravis, the Lambert Eaton syndrome and acquired neuromyotonia. However, evidence for the role of antibodies in conditions involving the central nervous system, is scanty or unclear. This review describes the ways in which the roles of autoantibodies have been defined in the peripheral diseases, and discusses the more controversial evidence for involvement of autoantibodies in some central disorders such as multiple sclerosis.

Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is viewed as a reactive, self-limited, autoimmune disease triggered by a preceding bacterial or viral infection. Campylobacter jejuni, a major cause of bacterial gastroenteritis worldwide, is the most frequent antecedent pathogen. It is likely that immune responses directed towards the infecting organisms are involved in the pathogenesis of GBS by cross-reaction with neural tissues. The infecting organism induces humoral and cellular immune responses that, because of the sharing of homologous epitopes (molecular mimicry), cross-react with ganglioside surface components of peripheral nerves. Immune reactions against target epitopes in Schwann-cell surface membrane or myelin result in acute inflammatory demyelinating neuropathy (85% of cases); reactions against epitopes contained in the axonal membrane cause the acute axonal forms of GBS (15% of cases). Care for such patients may be challenging, yet the prognosis overall is favourable. Optimal supportive care and anticipation and prevention of complications are the mainstay of therapy. Admission to the intensive-care unit is necessary in 33% of patients who require intubation and assisted ventilation. Immunomodulation with infusions of IgG or plasma exchange treatments foreshorten the disease course.

Campylobacter species and Guillain-Barré syndrome

Since the eradication of polio in most parts of the world, Guillain-Barré syndrome (GBS) has become the most common cause of acute flaccid paralysis. GBS is an autoimmune disorder of the peripheral nervous system characterized by weakness, usually symmetrical, evolving over a period of several days or more. Since laboratories began to isolate Campylobacter species from stool specimens some 20 years ago, there have been many reports of GBS following Campylobacter infection. Only during the past few years has strong evidence supporting this association developed. Campylobacter infection is now known as the single most identifiable antecedent infection associated with the development of GBS. Campylobacter is thought to cause this autoimmune disease through a mechanism called molecular mimicry, whereby Campylobacter contains ganglioside-like epitopes in the lipopolysaccharide moiety that elicit autoantibodies reacting with peripheral nerve targets. Campylobacter is associated with several pathologic forms of GBS, including the demyelinating (acute inflammatory demyelinating polyneuropathy) and axonal (acute motor axonal neuropathy) forms. Different strains of Campylobacter as well as host factors likely play an important role in determining who develops GBS as well as the nerve targets for the host immune attack of peripheral nerves. The purpose of this review is to summarize our current knowledge about the clinical, epidemiological, pathogenetic, and laboratory aspects of campylobacter-associated GBS.