Severe acute axonal form of Guillain-Barré syndrome associated with IgG anti-GD1a antibodies

Campylobacter jejuni and Postinfectious Autoimmune Diseases: A Proof of Concept in Glycobiology

Glycans, one of the most diverse groups of macromolecules, are ubiquitous constituents of all cells and have many critical functions, including the interaction between microbes and their hosts. One of the best model organisms to study the host-pathogen interaction, the gastrointestinal pathogen Campylobacter jejuni dedicates extensive resources to glycosylation and exhibits a diverse array of surface sugar-coated displays. The first bacterium where N-linked glycosylation was described, C. jejuni can additionally modify proteins by O-linked glycosylation, has extracellular capsular polysaccharides that are important for virulence and represent the major determinant of the Penner serotyping scheme, and has outer membrane lipooligosaccharides that participate in processes such as colonization, survival, inflammation, and immune evasion. In addition to causing gastrointestinal disease and extraintestinal infections, C. jejuni was also linked to postinfectious autoimmune neuropathies, of which Guillain-Barré syndrome (GBS) and Miller Fisher syndrome (MFS) are the most extensively characterized ones. These postinfectious autoimmune neuropathies occur when specific bacterial surface lipooligosaccharides mimic gangliosides in the host nervous system. C. jejuni provided the first proof of concept for the involvement of molecular mimicry in the pathogenesis of an autoimmune disease and, also, for the ability of a bacterial polymorphism to shape the clinical presentation of the postinfectious autoimmune neuropathy. The scientific journey that culminated with elucidating the mechanistic details of the C. jejuni-GBS link was the result of contributions from several fields, including microbiology, structural biology, glycobiology, genetics, and immunology and provides an inspiring and important example to interrogate other instances of molecular mimicry and their involvement in autoimmune disease.

Fcγ Receptor I-Coupled Signaling in Peripheral Nociceptors Mediates Joint Pain in a Rat Model of Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is often accompanied by joint pain and inflammation. Previous studies have demonstrated that functional Fcγ receptor I (FcγRI) is expressed in dorsal root ganglion (DRG) neurons and might contribute to pain in rodent models of antigen-induced arthritis (AIA). This study was undertaken to elucidate the roles of nociceptive neuronal FcγRI-coupled signaling in the development of joint pain in AIA.

METHODS

RNA sequencing was used to investigate the transcriptome profile changes in the DRG in a rat model of AIA. A primary sensory neuron-specific Fcgr1a conditional-knockout (CKO) rat was established by crossing rats carrying a loxP-flanked Fcgr1a with a Pirt-specific Cre line. Behavioral, morphologic, and molecular studies were conducted to evaluate the differences between wild-type (WT) and CKO rats after AIA.

RESULTS

We first showed that AIA induced a transcriptome profile change in the DRG, involving a number of key proteins downstream of the FcγRI-related signaling pathway. Compared to the WT rats, both the IgG immune complex-induced acute pain and AIA-induced pain were alleviated in CKO rats. Moreover, the AIA-induced activation of FcγRI-related signaling in DRGs was significantly reduced in CKO rats. In addition, CKO rats showed attenuated joint swelling after AIA.

CONCLUSION

These results indicate that activation of FcγRI-coupled signaling in DRG neurons plays an important role in the development of joint pain in AIA. Our findings may provide novel insights into the interactions between the peripheral nervous system and the immune system in pathologic conditions and might suggest potential biotargets for the treatment of pain in RA.

Guillain-Barré syndrome: What have we learnt during one century? A personal historical perspective

We are approaching the centenary of the first description of Guillain-Barré syndrome. The past 30 years had witnessed an amazing progress in the understanding of the immunological and pathological mechanisms of this disorder. We now recognize that Guillain-Barré syndrome is remarkably heterogeneous and under this umbrella term are several variants and subtypes with distinct clinical, electrophysiological and immunopathological features. This review is a historical journey, through a personal perspective, following the milestones that led to the current substantial knowledge of Guillain-Barré syndrome.

DNA diversity of the wla gene cluster among serotype HS:19 and non-HS:19 Campylobacter jejuni strains

Campylobacter jejuni infection is an important trigger of Guillain-Barré syndrome (GBS), and serotype HS:19 strains are over-represented among GBS-associated isolates. Structures in C. jejuni lipooligosaccharide (LOS) resemble human gangliosides, suggesting that molecular mimicry could be important in triggering the neural injury. We assessed the genetic diversity among 36 C. jejuni serotype HS:19 and non-HS:19 strains by analysis of PCR-based restriction fragment length polymorphism (RFLP) patterns of 12 LOS biosynthesis-related genes ( wla cluster). PCR amplification revealed that the size, order, and direction of each wla gene was identical among all strains tested. However, an additional ORF, located between wlaI and wlaK, was detected in 28 of the 36 isolates examined, and nucleotide sequence analysis revealed that the gene was identical to orfE in C. jejuni strain NCTC 11168. An inverted repeat motif was found downstream of the wlaI stop codon and upstream of the orfE stop codon, an organization allowing pairing of repeated sequences that could lead to deletion of the internal segment. Digestion of the PCR products with restriction endonuclease DdeI or AluI and cluster analysis of RFLP banding patterns showed that all HS:19 strains were closely related and distinct from non-HS:19 strains, consistent with earlier analyses, suggesting that HS:19 strains represent a highly clonal population. RFLP analysis of wla genes also may be useful for epidemiological studies.

Antibody cross-reactivities between gangliosides and lipopolysaccharides of Campylobacter jejuni serotypes associated with Guillain-Barré syndrome

Ganglioside-antibodies produced subsequent to Campylobacter jejuni infection may play a role in the pathogenesis of the neurological disorder Guillain-Barré syndrome (GBS). Since lipopolysaccharides (LPS) of certain C. jejuni serotypes associated with GBS (O:2, O:4, O:19) exhibit structural mimicry of gangliosides in their core oligosaccharides, we investigated antibody and ligand cross-reactivities between gangliosides and LPS of these C. jejuni serotypes. GM1-antibody reacted with O:19 LPS reflecting GM1 mimicry by the O:19 core oligosaccharide. On the other hand, asialoGM1-antibody bound to O:2 and O:19 LPS indicating a shared epitope not dependent on ganglioside mimicry. Serum IgA from GBS patients after C. jejuni infection reacted with gangliosides, predominantly GM1, and LPS of all three serotypes. Cholera toxin (GM1 ligand) recognized O:4 and O:19 LPS, whereas peanut agglutinin (Galβ1-3GalNAc ligand) recognized LPS of all three serotypes, thereby confirming structural mimicry. These results suggest that LPS from certain C. jejuni strains may function as cross-reactive antigens for anti-ganglioside B cells.

Unexpected Rapid Improvement and Neurogenic Stunned Myocardium in a Patient With Acute Motor Axonal Neuropathy: A Case Report and Literature Review

Acute Motor Axonal Neuropathy-type Guillain-Barré Syndrome (GBS) is a subset of GBS with either a rapidly improving or protracted course that was first described in China. We describe a 27-year-old previously healthy woman with weakness that progressed to complete tetraplegia and areflexia within 2 weeks after an upper respiratory illness. A lumbar puncture performed 4 days after onset of neurologic symptoms was inconclusive for GBS, and electromyography revealed complete motor axonal neuropathy. The patient had Mycoplasma pneumoniae in her nares and blood, and several antiganglioside antibodies in her blood. She was treated with plasmapheresis, antibiotics, and physical therapy. Her motor function and reflexes improved rapidly with treatment, and she was able to ambulate within 3 weeks. She also experienced cardiomyopathy, which improved with plasmapheresis. We report a rare case of Mycoplasma pneumonia-associated acute motor axonal neuropathy-type GBS presenting with complete tetraplegia, areflexia, and neurogenic stunned myocardium that rapidly improved with plasmapheresis.

Infectious and noninfectious triggers in Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is the commonest cause of acquired flaccid paralysis in the world and regarded by many as the prototype for postinfectious autoimmunity. Here the authors consider both infectious and noninfectious triggers of GBS and determine where possible what immunological mechanisms may account for this association. In approximately two-thirds of cases, an infectious trigger is reported in the weeks that lead up to disease onset, indicating that the host's response to infection must play an important role in disease pathogenesis. The most frequently identified bacteria, Campylobacter jejuni, through a process known as molecular mimicry, has been shown to induce cross-reactive anti-ganglioside antibodies, which can lead to the development of axonal-type GBS in some patients. Whether this paradigm can be extended to other infectious organisms or vaccines remains an important area of research and has public health implications. GBS has also been reported rarely in patients with underlying systemic diseases and immunocompromised states and although the exact mechanism is yet to be established, increased susceptibility to known infectious triggers should be considered most likely.

Pharyngeal-cervical-brachial variant of Guillain-Barre syndrome

The pharyngeal-cervical-brachial (PCB) variant of Guillain-Barré syndrome is defined by rapidly progressive oropharyngeal and cervicobrachial weakness associated with areflexia in the upper limbs. Serial nerve conduction studies suggest that PCB represents a localised subtype of Guillain-Barré syndrome characterised by axonal rather than demyelinating neuropathy. Many neurologists are unfamiliar with PCB, which is often misdiagnosed as brainstem stroke, myasthenia gravis or botulism. The presence of additional ophthalmoplegia and ataxia indicates overlap with Fisher syndrome. Half of patients with PCB carry IgG anti-GT1a antibodies which often cross-react with GQ1b, whereas most patients with Fisher syndrome carry IgG anti-GQ1b antibodies which always cross-react with GT1a. Significant overlap between the clinical and serological profiles of these patients supports the view that PCB and Fisher syndrome form a continuous spectrum. In this review, we highlight the clinical features of PCB and outline new diagnostic criteria.

Fcγ receptor-mediated inflammation inhibits axon regeneration

Anti-glycan/ganglioside antibodies are the most common immune effectors found in patients with Guillain-Barré Syndrome, which is a peripheral autoimmune neuropathy. We previously reported that disease-relevant anti-glycan autoantibodies inhibited axon regeneration, which echo the clinical association of these antibodies and poor recovery in Guillain-Barré Syndrome. However, the specific molecular and cellular elements involved in this antibody-mediated inhibition of axon regeneration are not previously defined. This study examined the role of Fcγ receptors and macrophages in the antibody-mediated inhibition of axon regeneration. A well characterized antibody passive transfer sciatic nerve crush and transplant models were used to study the anti-ganglioside antibody-mediated inhibition of axon regeneration in wild type and various mutant and transgenic mice with altered expression of specific Fcγ receptors and macrophage/microglia populations. Outcome measures included behavior, electrophysiology, morphometry, immunocytochemistry, quantitative real-time PCR, and western blotting. We demonstrate that the presence of autoantibodies, directed against neuronal/axonal cell surface gangliosides, in the injured mammalian peripheral nerves switch the proregenerative inflammatory environment to growth inhibitory milieu by engaging specific activating Fcγ receptors on recruited monocyte-derived macrophages to cause severe inhibition of axon regeneration. Our data demonstrate that the antibody orchestrated Fcγ receptor-mediated switch in inflammation is one mechanism underlying inhibition of axon regeneration. These findings have clinical implications for nerve repair and recovery in antibody-mediated immune neuropathies. Our results add to the complexity of axon regeneration in injured peripheral and central nervous systems as adverse effects of B cells and autoantibodies on neural injury and repair are increasingly recognized.

Pathogenesis of Guillain–Barré syndrome

Guillain-Barre syndrome is a postinfectious disorder caused by an aberrant immune response to an infectious pathogen, resulting in an autoimmune disease. As with other autoimmune diseases of infectious nature, the intricate balance of the numerous factors involved in the immune response may determine the outcome of the interaction between the microbe and host. Recent studies focusing on the role of cytokines and its network of related mediators and receptors suggest that any imbalance may make a significant contribution to the outcome of the infectious disease process. Better understanding of the pathogenesis of Guillain-Barre syndrome may lead to the discovery of newer therapeutics and may also serve as a model for studying other autoimmune diseases.

Antibody testing in peripheral nerve disorders

The identification of autoantibodies associated with dysimmune neuropathies was a major contribution to the characterization of peripheral nerve disorders, the understanding of their pathophysiology, and the clinical diagnosis of neuropathies. Antibodies directed to GM1, GQ1b, and disyalilated gangliosides, and anti-MAG antibodies are very useful in the diagnosis of acute or chronic motor or sensory-motor neuropathies with or without monoclonal IgM. Anti-onconeural anti-Hu and anti-CV2/CRMP antibodies allow when they are detected the diagnosis of paraneoplastic neuropathies. This chapter focuses on the description of these antibodies as diagnostic markers and on their immunopathogenesis. We give a background overview on the origin of these antibodies, their detection, and review those studies, which clearly show that these antibodies are capable of binding to the target tissues in peripheral nerve and thereby can exert a variety of pathophysiological effects. The corresponding electrophysiological and histological changes observed both in human and animal models are exemplified in order to get a better understanding of the immune mechanisms of these antibody-mediated neuropathies.

Polycranial neuropathy and sensory ataxia with IgG anti-GD1a antibody as a variant of Guillain-Barré syndrome

Immunoglobulin G (IgG) anti-GD1a ganglioside antibody is an important marker of Guillain-Barré syndrome (GBS). This antibody is highly associated with disease severity, the need for mechanical ventilation, and axonal degeneration of peripheral nerves. We report a 46-year-old female patient manifesting the IgG anti-GD1a antibody with polycranial neuropathy and sensory ataxia as a variant of GBS. She presented with slurred speech, swallowing difficulties, and gait disturbance following diarrhea. Decreased sensations of vibration and position were found in her distal limbs and she had an ataxic gait with a positive Romberg sign. Her serum was positive for IgG anti-GD1a ganglioside antibody (1:640). Her neurological examination at the third month after intravenous Ig treatment showed complete recovery.

[Guillain-Barré syndrome after exposure to influenza]

Guillain-Barré Syndrome (GBS) is an acquired, monophasic inflammatory polyradiculoneuritis of autoimmune origin, which occurs after infection and occasionally also after vaccination. Seasonal and pandemic influenza vaccines have in particular been implicated as triggers for GBS. However, a number of recent studies indicate that infection with influenza virus may also cause GBS. This review summarizes the epidemiological and experimental data of the association of GBS with exposure to influenza antigens by immunization (including vaccines against A/H1N1/2009) and infection. Vaccination against influenza is associated with a very low risk for the occurrence of GBS. In contrast infection with influenza may play a more important role as a triggering factor for GBS than previously assumed.

Efficiently synthesizing lacto-ganglio-series gangliosides by using a glucosyl ceramide cassette approach: the total synthesis of ganglioside X2

The first total synthesis of the hybrid ganglioside X2, which consisted of a highly branched octasaccharide and ceramide moieties, was accomplished by using a glucosyl ceramide cassette approach. With a disaccharyl donor, the heptasaccharide could not be constructed by glycosylation of the C4 hydroxy group of galactose at the reducing end of the pentasaccharide. In contrast, through an alternative approach with two branched glycan units, a GM2-core trisaccharide, and a lacto-ganglio tetrasaccharide, the heptasaccharyl donor could be prepared and subsequently joined with a glucosyl ceramide cassette to afford the protected ganglioside, X2. Finally, global deprotection completed the synthesis, thus affording the pure ganglioside X2.

Neuronal Fc-gamma receptor I mediated excitatory effects of IgG immune complex on rat dorsal root ganglion neurons

Pain often accompanies antigen-specific immune-related disorders though little is known of the underlying neural mechanisms. A common feature among these disorders is the elevated level of antigen-specific immunoglobulin (Ig) G in the serum and the presence of IgG immune complex (IC) in the affected tissue. We hypothesize that IC may directly activate the Fc-gamma receptor type I (FcγRI) expressed in nociceptive dorsal root ganglion (DRG) neurons and increase neuronal excitability thus potentially contributing to pain. Immunofluorescent labeling indicated that FcγRI, but not FcγRIIB or FcγRIII, was expressed in a subpopulation of rat DRG neurons including those expressing nociceptive markers. Calcium imaging revealed that the IC, but neither of the antibody (IgG) or antigen alone, produced an increase in intracellular calcium. This effect was abolished by the removal of the IgG Fc portion in the IC or the application of an anti-FcγRI antibody, suggesting a key role of the FcγRI receptor. Removal of extracellular calcium or depletion of intracellular calcium stores prevented the IC-induced calcium response. In whole-cell current-clamp recordings, IC depolarized the resting membrane potential, decreased the rheobase, and increased the number of action potentials evoked by a depolarizing current at 2× rheobase. In about half of the responsive neurons, IC evoked action potential discharges. These results suggest that a subpopulation of nociceptive neurons expresses functional FcγRI and that the activation of this receptor by IC increases neuronal excitability.

Plasma exchange and intravenous immunoglobulins: mechanism of action in immune-mediated neuropathies

Immune-mediated neuropathies are a heterogeneous group of peripheral nerve disorders, which are classified by time course, clinical pattern, affected nerves and pathological features. Plasma exchange (PE) and intravenous immunoglobulins (IVIg) are mainstays in the treatment of immune-mediated neuropathies. Of all treatments currently used, IVIg has probably the widest application range in immune-mediated neuropathies and efficacy has been well documented in several randomized controlled trials for Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy (CIDP). Beneficial effects of IVIg have also been proven for multifocal motor neuropathy (MMN). Likewise, PE is an established treatment for GBS and CIDP, whereas it is considered to be ineffective in MMN. Different mechanisms of action are sought to be responsible for the immunemodulatory effect of PE and IVIg in autoimmune disorders. Some of those might be important for immune-mediated neuropathies, while others are probably negligible. The aim of this review is to summarize the recent advances in elucidating disease-specific mechanisms of actions of PE and IVIg in the treatment of immune-mediated neuropathies.

A first total synthesis of a hybrid-type ganglioside associated with amyotrophic lateral sclerosis-like disorder

The hybrid ganglioside X1, which was identified in the bovine brain, was synthesized for the first time. Ganglioside X1 is believed to be involved in the development of amyotrophic lateral sclerosis-like disorders in patients with neurological disorders after treatment with bovine brain gangliosides. A convergent approach using two branched glycan units, the GM2-core trisaccharide and the lacto-ganglio tetrasaccharide, efficiently provided the highly branched heptasaccharide part of ganglioside X1, which was conjugated with the ceramide part to produce the protected ganglioside X1. Global deprotection delivered homogenous ganglioside X1, with which serum from the patient was reacted.

Guillain-Barré syndrome after exposure to influenza virus

Guillain-Barré syndrome (GBS) is an acute, acquired, monophasic autoimmune disorder of peripheral nerves that develops in susceptible individuals after infection and, in rare cases, after immunisation. Exposure to influenza via infection or vaccination has been associated with GBS. We review the relation between GBS and these routes of exposure. Epidemiological studies have shown that, except for the 1976 US national immunisation programme against swine-origin influenza A H1N1 subtype A/NJ/76, influenza vaccine has probably not caused GBS or, if it has, rates have been extremely low (less than one case per million vaccine recipients). By contrast, influenza-like illnesses seem to be relevant triggering events for GBS. The concerns about the risk of inducing GBS in mass immunisation programmes against H1N1 2009 do not, therefore, seem justified by the available epidemiological data. However, the experiences from the 1976 swine flu vaccination programme emphasise the importance for active and passive surveillance to monitor vaccine safety.

An update on pathobiologic roles of anti-glycan antibodies in Guillain-Barré syndrome

Anti-glycan antibodies directed against gangliosides are now considered the major immune effectors that induce damage to intact nerve fibers in some variants of the monophasic neuropathic disorders that comprise Guillain-Barré syndrome. Recent experimental studies elucidating the complexity of anti-glycan antibody-mediated pathobiologic effects on intact and injured nerves undergoing repair are discussed.

Axonal Guillain-Barré syndrome: carbohydrate mimicry and pathophysiology

Acute motor axonal neuropathy (AMAN), an axonal subtype of Guillain-Barré syndrome (GBS), is characterized by pure motor involvement, frequent antecedent infection by Campylobacter jejuni, association with anti-GM1 or anti-GD1a immunoglobulin G (IgG) antibodies, and the electrophysiological features of axonal degeneration and reversible conduction block. Molecular mimicry exists between GM1 and GD1a gangliosides and lipooligosaccharides (LOSs) of C. jejuni isolates from AMAN. Sensitization of rabbits with GM1 or C. jejuni LOS induces anti-GM1 IgG antibodies and subsequent flaccid paralysis. Pathological changes seen in rabbit model peripheral nerves are identical to those in human AMAN. Immunohistochemistry of AMAN rabbits shows disruption of nodal sodium channel clusters and detachment of paranodal myelin terminal loops, similar to paranodal demyelination, which would significantly reduce the safety factor for impulse transmission and might be responsible for the rapidly reversible conduction block frequently present in human AMAN. C. jejuni sialyltransferase (Cst-II), which functions in the biosynthesis of ganglioside-like LOSs, determines the transferase activity. Strains with cst-II (Thr51) express GM1 and GD1a epitopes, whereas GBS patients infected with cst-II (Thr51) strains have anti-GM1 or anti-GD1a IgG antibodies. The cst-II gene is responsible for the development of GBS. Immunological, pathological, electrophysiological, and bacteriological studies have provided strong evidence of carbohydrate mimicry being a cause of AMAN and clarified the mechanisms of nerve conduction failure in AMAN.

October 1996--rapidly progressive weakness

One week after a flu-like illness, a 51-year-old woman developed rapidly progressive weakness. Within three weeks, she required mechanical ventilation. A neurological exam revealed severe motor involvement with normal sensory findings confirmed by nerve conduction studies. Five days after intubation a catastrophic brain hemorrhage occurred. Autopsy showed severe loss of axons in the motor roots with periaxonal macrophages and no lymphocytes. These findings are typical of acute motor axonal neuropathy, which is rare in the United States.

Antibody testing in peripheral neuropathies

Many autoantibodies have been described in association with peripheral neuropathy, but the use of antibody testing in clinical practice remains a matter of some debate. Serum autoantibodies to gangliosides or glycoproteins are implicated in a variety of sensory and motor neuropathy syndromes. Paraneoplastic antibodies help identify patients who have a neuropathy related to an underlying malignancy. Detection of an autoantibody in the right clinical setting provides some evidence that the peripheral nerve disturbance is immune mediated and that immunomodulatory therapy may be of benefit.

Ganglioside mimicry and peripheral nerve disease

Four criteria must be satisfied to conclude that a given microorganism causes Guillain-Barré (GBS) or Fisher (FS) syndrome associated with anti-ganglioside antibodies: (1) an epidemiological association between the infecting microbe and GBS or FS; (2) isolation in the acute progressive phase of illness of that microorganism from GBS or FS patients with associated anti-ganglioside IgG antibodies; (3) identification of a microbial ganglioside mimic; and (4) a GBS or FS with associated anti-ganglioside antibodies model produced by sensitization with the microbe itself or its component, as well as with ganglioside. Campylobacter jejuni is a definitive causative microorganism of acute motor axonal neuropathy and may cause FS and related conditions. Haemophilus influenzae and Mycoplasma pneumoniae are possible causative microorganisms of acute motor axonal neuropathy or FS. Acute and chronic inflammatory demyelinating polyneuropathies may be produced by mechanisms other than ganglioside mimicry.

Experimental axonopathy induced by immunization with Campylobacter jejuni lipopolysaccharide from a patient with Guillain-Barré syndrome

New Zealand white rabbits were immunized with a lipopolysaccharide (LPS) extracted from a Campylobacter jejuni HS:19 strain isolated from a GBS patient expressing GM1 and GD1a-like epitopes, Freund's adjuvant (group I) and Freund's adjuvant plus keyhole lympet hemocyanin (KLH) (group II). Both groups showed high titers of anti-LPS and anti-GM1 and lower titers of anti-GD1b and anti-GD1a antibodies. Weakness and axonal degeneration in sciatic nerves was detected in 1/11 of group I and 6/7 of group II. This model replicates, at least in part, the pathogenetic process hypothesized in the human axonal GBS with antiganglioside antibodies post C. jejuni infection and indicates that KLH plays an additional role in neuropathy induction.

On the early diagnosis of IVIg-responsive chronic multifocal acquired motor axonopathy

Multifocal acquired motor axonopathy (MAMA) is a treatable, immune mediated motor neuropathy with purely axonal electrophysiological features. Distinction from degenerative neuronopathies such as progressive muscular atrophy (PMA) or early motor neuron disease (MND) can be difficult because of the similar clinical and electrophysiological findings. Here, we report the clinical, electrophysiological and laboratory findings in 6 patients with MAMA. Electrophysiological testing showed purely axonal findings with evidence of pathological spontaneous activity and chronic neurogenic changes. Of particular note, pathological spontaneous activity in paraspinal myotoms was not detectable in any of the patients even though it had been documented in peripheral muscles of the corresponding myotome(s). Elevated serum ganglioside antibody levels,most frequently anti-GD1a antibodies, were present in all 6 patients. IV Ig treatment led to clinical improvement in all but one patient, who showed an allergic response when exposed to IVIg. Our findings indicate that paraspinal EMG and anti-GD1a antibodies can facilitate the early identification of treatable, IVIg responsive, patients with MAMA.

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.

Plasma immunoadsorption therapy for Guillain-Barré syndrome: critical day for initiation

Immunoadsorption plasmapheresis (IAPP) is a method of removing circulating immune factors that is used to treat Guillain-Barré syndrome (GBS). We retrospectively analyzed the data on our GBS patients. In 21 patients treated with IAPP, linear regression analysis showed that the time from the onset of symptoms to the initiation of IAPP was correlated with the time required for improvement by one Hughes functional grade. We investigated the critical day for initiating treatment, which we defined as the day when initiation of IAPP was significantly more likely to improve function by at least one Hughes grade when compared with the outcome in patients receiving supportive therapy (non-IAPP group). The critical day was found to be day 6 after the onset of GBS.

Sialosyl-galactose: a common denominator of Guillain-Barré and related disorders?

The immune reactivity implicated in the pathogenesis of Guillain-Barré syndrome (GBS) and related diseases, which occur following infection with specific strains of Campylobacter jejuni bearing sialylated lipopolysaccharide structures that cross-react with specific gangliosides, is consistent with provocation of inflammation via molecular mimicry. In this review, we have focused upon microbial characteristics and structures, the fine structure of the essential carbohydrate determinants, and the application of our proposed criteria, modified from those of Koch for causation of infectious and of Witebsky for autoimmune diseases, to the circumstance of infectious induction of autoimmune disorder.

Chronic effects of Campylobacter infection

Campylobacter jejuni is one of the most common causes of bacterial gastroenteritis and chronic sequelae, such as reactive arthritis and Guillain-Barré syndrome (GBS), are known to follow uncomplicated infections. While little is known about reactive arthritis following Campylobacter infection, our knowledge on the pathogenesis of Campylobacter-induced GBS is expanding rapidly and is summarized in this review.

Anti-GD1a antibodies from an acute motor axonal neuropathy patient selectively bind to motor nerve fiber nodes of Ranvier

Acute motor axonal neuropathy (AMAN) is associated with high titer anti-GD1a antibodies. We have found that very high titer IgG anti-GD1a antibodies (Ab) from one AMAN patient selectively bind to motor, but not sensory, nerve nodes of Ranvier. Binding is abolished by preadsorption with GD1a. Sera negative for Ab do not immunostain motor and sensory nerve roots. We have also found that botulinum toxin A (BTA), which binds to GD1a, stains both motor and sensory nerve nodes of Ranvier. Our results strongly support the pathogenetic role of anti-GD1a antibodies in AMAN. Why BTA also binds to sensory fibers still remains to be elucidated, although the different size of BTA and its specificity to other gangliosides present in sensory axons might represent important factors.

Infectious origins of, and molecular mimicry in, Guillain-Barré and Fisher syndromes

Guillain-Barré syndrome (GBS), characterised by limb weakness and areflexia, is the prototype of postinfectious autoimmune diseases, and Campylobacter jejuni is the most frequent antecedent pathogen. GBS subsequent to C jejuni enteritis is associated with a severe, pure motor axonal variant and IgG antibodies against GM1, GM1b, GD1a, or GalNAc-GDla, gangliosides expressed in human peripheral nerves. Lipopolysaccharides of C jejuni isolated from GBS patients have ganglioside-like epitopes. Cytomegalovirus is the most common viral antecedent infection. Patients with demyelinating GBS who have had a recent CMV infection have severe sensory deficits and anti-GM2 IgM antibody. CMV-infected fibroblasts express the GM2 epitope. Fisher syndrome (FS), characterised by ophthalmoplegia, ataxia, and areflexia, is a GBS variant associated with anti-GQ1b IgG antibody. GQ1b is enriched in the cranial nerves that innervate the extraocular muscles. Some patients develop FS after C jejuni infection, and the lipopolysaccharide present bears the GQ1b epitope. Molecular mimicry is a possible cause of GBS and FS.

Axonal Guillain-Barré syndrome: a critical review

Axonal Guillain-Barré Syndrome (GBS) was first described by Feasby et al. in 1986, challenging the existent notion of GBS being a primarily demyelinating disease. The severe course and slow recovery commonly seen in these patients was ascribed to axonal degeneration. Other authors challenged this claim on several grounds. Amidst these controversies, epidemics of a similar illness were reported from China, which were given the acronym AMAN, having exclusive motor involvement in contrast to the cases already described in which both motor and sensory involvement were present (AMSAN). Pathologically, Wallerian degeneration, minimal lymphocytic response, absent demyelination or inflammation and periaxonal macrophages are prominent features. Ultrastructural studies have revealed node of Ranvier to be the prime target of immune attack. A frequent occurrence of antecedent Campylobacter jejuni infection and a strong association between elevated titres of IgG GM1 and axonal GBS on a background of preceding C. jejunii infection has been observed and molecular mimicry between lipopolysaccharides of C. jejuni and neural epitopes has been proposed as a mechanism of injury. Clinically axonal variant is similar to AIDP, but a more severe course, with frequent respiratory involvement, ventilator dependence and significant residue may be seen. Diagnosis is essentially electrophysiological. Treatment is similar to AIDP, preferential benefit of either IVIG or plasmapheresis needs to be further evaluated. A critical review of existing literature in axonal GBS is presented.

Peripheral neuropathy associated with anti-GM2 ganglioside antibodies: clinical and immunopathological studies

GM2 ganglioside is a potential peripheral nerve antigen for neuropathy-associated autoantibodies. However little data are available on their pathogenic effects, if any. In this study we have screened both neuropathy-associated and control sera for anti-GM2 antibodies and subsequently used high titre sera for immunohistological and complement mediated cytotoxicity studies. We identified abnormally elevated anti-GM2 antisera in the normal population, as well as in patients with peripheral neuropathies and other neurological diseases. GM2 antibodies were either mono-reactive, cross-reactive with GM1a, or cross-reactive with GalNAc-GM1b and/or GalNAc-GD1a. All GM2 antisera from neuropathy subjects and normal controls bound to, and were capable of complement-mediated lysis of the NSC-34 cell line which expresses high levels of membrane-associated GM2. However, in immunohistological studies on human and rodent peripheral nervous system tissues, no specific binding was seen with GM2 antisera, either cross-reactive with GalNAc-GM1b and GalNAc-GDla, or with GM1a. These data indicate that although GM2 antisera can lyse neural membranes containing GM2, this antigen(s) is not detectable by standard immunohistological techniques in human or rodent peripheral nerve. This raises doubts about their pathophysiological significance in human autoimmune neuropathy.

Antibodies to GM1(NeuGc) in Guillain-Barré syndrome after ganglioside therapy

N-Glycolylneuraminic acid-containing GM1 [GM1(Gc)] is a molecule for serum antibodies in patients with Guillain-Barré syndrome (GBS). To clarify the pathogenesis of GBS after treatment with bovine brain ganglioside, we investigated the presence of anti-GM1(Gc) antibody in patients who developed GBS after ganglioside injection. Serum samples were taken from nine Italian patients with GBS after ganglioside therapy as well as from untreated Italian (n=30) and Japanese (n=131) GBS patients. Bovine brain gangliosides fractionated in a column were used as antigens, and binding of serum IgG or IgM was examined. An absorption study of IgG anti-GM1(Gc) antibody was made with GM1, asialo-GM1, GM2, GD1a, and GD1b. Four of the nine patients who developed GBS after being administered gangliosides had IgG anti-GM1(Gc) antibodies. Anti-GM1(Gc) IgG antibody frequencies were higher in patients with GBS after ganglioside therapy than in those who were untreated. Rates of absorption of IgG anti-GM1(Gc) antibodies by GM1 were significantly higher (except for asialo-GM1 and GD1b) than by GM2 and GD1a. The presence of GM1(Gc) was confirmed in bovine brain immunochemically using cholera toxin and Hanganutziu-Deicher antibody. Secondary ion mass spectra showed that the structure of the ganglioside was consistent with that of GM1(Gc). GM1(Gc) was recognized more frequently in sera from patients who developed GBS after ganglioside therapy than in sera from untreated GBS patients. Because N-glycolylneuraminic acid-containing gangliosides seem to be highly immunogenic in humans, GM1(Gc) may act as an immunogen in some patients who develop GBS following ganglioside therapy.

Pathogenesis of Guillain-Barré syndrome

Recent neurophysiological and pathological studies have led to a reclassification of the diseases that underlie Guillain-Barré syndrome (GBS) into acute inflammatory demyelinating polyradiculoneuropathy (AIDP), acute motor and sensory axonal neuropathy (AMSAN) and acute motor axonal neuropathy (AMAN). The Fisher syndrome of ophthalmoplegia, ataxia and areflexia is the most striking of several related conditions. Significant antecedent events include Campylobacter jejuni (4-66%), cytomegalovirus (5-15%), Epstein-Barr virus (2-10%), and Mycoplasma pneumoniae (1-5%) infections. These infections are not uniquely associated with any clinical subtype but severe axonal degeneration is more common following C. jejuni and severe sensory impairment following cytomegalovirus. Strong evidence supports an important role for antibodies to gangliosides in pathogenesis. In particular antibodies to ganglioside GM1 are present in 14-50% of patients with GBS, and are more common in cases with severe axonal degeneration associated with any subtype. Antibodies to ganglioside GQ1b are very closely associated with Fisher syndrome, its formes frustes and related syndromes. Ganglioside-like epitopes exist in the bacterial wall of C. jejuni. Infection by this and other organisms triggers an antibody response in patients with GBS but not in those with uncomplicated enteritis. The development of GBS is likely to be a consequence of special properties of the infecting organism, since some strains such as Penner 0:19 and 0:41 are particularly associated with GBS but not with enteritis. It is also likely to be a consequence of the immunogenetic background of the patient since few patients develop GBS after infection even with one of these strains. Attempts to match the subtypes of GBS to the fine specificity of anti-ganglioside antibodies and to functional effects in experimental models continue but have not yet fully explained the pathogenesis. T cells are also involved in the pathogenesis of most or perhaps all forms of GBS. T cell responses to any of three myelin proteins, P2, PO and PMP22, are sufficient to induce experimental autoimmune neuritis. Activated T cells are present in the circulation in the acute stage, up-regulate matrix metalloproteinases, cross the blood-nerve barrier and encounter their cognate antigens. Identification of the specificity of these T cell responses is still at a preliminary stage. The invasion of intact myelin sheaths by activated macrophages is difficult to explain according to a purely T cell mediated mechanism. The different patterns of GBS are probably due to the diverse interplay between antibodies and T cells of differing specificities.

Multiple sclerosis is associated with enhanced B cell responses to the ganglioside GD1a

The occurrence and role of autoantibodies to gangliosides and other lipid-containing components of the central nervous system in Multiple Sclerosis (MS) are unsettled. Using sensitive ELISAs, we measured IgG and IgM antibody titers and absorbances to the three major gangliosides GD1a, GD1b and GM1, and to sulfatides, cardiolipin and myelin proteins in paired serum and cerebrospinal fluid (CSF) from patients with untreated MS, optic neuritis (ON), acute aseptic meningo-encephalitis (AM) and other neurological diseases (OND). Twenty-three per cent of 30 MS (P<0.04) and 18% of 32 ON patients (P<0.05) presented elevated IgG antibody titers to GD1a in serum compared to 9% of patients with OND. Six (40%) of the patients with malignant MS had elevated serum IgG antibody titers to GD1a compared to one (6%) of the patients with benign MS (P<0.04). In CSF, elevated IgG antibody titers to GD1a were measured in 13% of MS and 20% of ON patients compared to 4% of patients with OND (P<0. 03 and P<0.02, respectively). The augmented IgG response to GD1a in serum also separated MS from Guillain-Barré syndrome. Compared to OND increased IgM absorbances to sulfatides and cardiolipin were observed in CSF of patients with MS, but also in AM. Elevated IgG antibody titers to myelin proteins were found more often in MS patients' serum and MS, ON and AM patients' CSF compared to OND. The data implicate that among the multitude of enhanced B-cell responses occurring in MS and ON, that directed to GD1a is common and more discriminative, and should be evaluated in future MS treatment studies.

Clinical presentation and outcome of Guillain-Barré and related syndromes in relation to anti-ganglioside antibodies

We correlated the clinical features of 78 patients with Guillain-Barré syndrome (GBS) or related variants, with the presence of serum antibodies to the gangliosides GM1, GM2, GD1a, GD1b and GQ1b in order to determine whether these antibodies may influence the clinical presentation or outcome of GBS. Sixty-three patients had typical GBS (81%), nine a pure motor form (11%), three a paraparetic form (4%), and three had Miller Fisher syndrome (MFS). IgG or IgM (or both) anti-ganglioside antibodies were found by ELISA in 37% of patients, including 36% with typical, 33% with pure motor and 100% with MFS. Beside the constant occurrence of anti-GQ1b antibodies in patients with MFS (P<0.00001), the other clinical forms were not associated with a specific anti-ganglioside reactivity. Anti-GM1 and anti-GD1a antibodies tended to be associated with a worse disability at 6 month than other or no reactivity and, similarly to anti-GM2 antibodies, with a more frequent respiratory impairment. Anti-GM2 and anti-GD1b antibodies were always associated with typical GBS and, in all but one patient, with a complete recovery; still they were found in only 13 and 3%, respectively, of the patients with this presentation. Anti-GQ1b antibodies, though always associated with ophthalmoplegia and ataxia in both MFS and GBS, were found in only 36 and 26%, respectively, of patients with these symptoms. Even if different anti-ganglioside antibodies tend to be associated with some clinical features possibly suggesting that they may influence the clinical presentation or outcome, with the exception of anti-GQ1b antibodies for ophthalmoplegia and ataxia, they do not permit to predict the clinical presentation or outcome in individual patients.

Subclass distribution and the secretory component of serum IgA anti-ganglioside antibodies in Guillain-Barré syndrome after Campylobacter jejuni enteritis

Previously, we reported that IgA anti-GM1 antibody is more closely associated with preceding Campylobacter jejuni enteritis in Guillain-Barré syndrome (GBS) than are IgG and IgM antibodies. However, the mechanism of the induction of IgA anti-ganglioside antibodies is not clear. In this study, serum IgA antibodies against GM1, GM1b, and GD1a, and GalNAc-GD1a were examined in 152 GBS patients. In GBS, antecedent C. jejuni infection is closely associated with IgA antibodies, other than GM1, against GM1b. The IgA subclass distribution is completely restricted to IgA1, no secretory IgA anti-ganglioside antibody being detected. This result does not support the hypothesis that the serum IgA antibodies present in GBS after C. jejuni enteritis originate at mucosal sites, such as the gut mucosal immune system. Seventeen (85%) of 20 patients with IgA anti-ganglioside antibodies had serological evidence of C. jejuni infection and/or a history of antecedent diarrhea. Moreover, a motor nerve conduction study showed that patients with IgA antibodies frequently had axonal neuropathy, whereas none had demyelinating neuropathy. This may support the previous report that IgA isotype anti-GM1 antibodies are more closely associated with poor outcome than are the IgG or IgM isotypes. The induction mechanism of IgA anti-ganglioside antibodies must be clarified by determining whether concentrations of cytokines, which increase the IgA class switch, are elevated in patients with GBS after C. jejuni enteritis.

Anti-GD1a antibody is associated with axonal but not demyelinating forms of Guillain-Barré syndrome

Immunopathological studies suggest that the target of immune attack is different in the subtypes of Guillain-Barré syndrome (GBS). In acute motor axonal neuropathy (AMAN), the attack appears directed against the axolemma and nodes of Ranvier. In acute inflammatory demyelinating polyneuropathy (AIDP), the attack appears directed against a component of the Schwann cell. However, the nature of the antigenic targets is still not clear. We prospectively studied 138 Chinese GBS patients and found that IgG anti-GD1a antibodies were closely associated with AMAN but not AIDP. With a cutoff titer of greater than 1:100, 60% of AMAN versus 4% of AIDP patients had IgG anti-GD1a antibodies; with a cutoff titer of greater than 1:1,000, 24% of AMAN patients and none of the AIDP patients had IgG anti-GD1a antibodies. In contrast, low levels of IgG anti-GM1 antibodies (> 1:100) were detected in both the AMAN and the AIDP forms (57% vs 35%, NS). High titers of IgG anti-GM1 (>1:1,000) were more common in the AMAN form (24% vs 8%, NS). Serological evidence of recent Campylobacter infection was detected in 81% of AMAN and 50% of AIDP patients, and anti-ganglioside antibodies were common in both Campylobacter-infected and noninfected patients. Our results suggest that IgG anti-GD1a antibodies may be involved in the pathogenesis of AMAN.

Acute and chronic neuropathies: new aspects of Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy, an overview and an update

During the last 15 years new information about clinical, electrophysiological, immunological and histopathological features of acute and chronic inflammatory neuropathies have emerged. Thus, the Guillain-Barré syndrome (GBS) is no longer considered a simple entity. Subtypes of the disorder besides the typical predominant motor manifestation, are recognized, i.e. a cranial nerve variant with ophthalmoplegia, ataxia and areflexia, an immune-mediated primary motor axonal neuropathy (AMAN), and a motor-sensory syndrome (AMSAN). Also, the clinical pattern of GBS is related to preceding viral or bacterial infections. Two types of acute motor paralysis have been described, one with slow and incomplete recovery, another with recovery times identical with acute inflammatory demyelinating polyneuropathy (AIDP). Histologically, the first is characterized by Wallerian degeneration of motor roots and peripheral motor nerve fibres. In the latter anti-GM antibodies bind to the nodes of Ranvier producing a failure of impulse transmission. Motor-point biopsies have shown denervated neuromuscular junctions and a reduced number of intramuscular nerve fibres. Molecular mimicry has been postulated as a possible mechanism triggering GBS. Thus, in the cranial variant antibodies to ganglioside GQ1b recognizes similar epitopes on Campylobacter jejuni strains and similar observations apply to anti-GM1 antibodies. Chronic inflammatory demyelinating polyneuropathy (CIDP) also has several different clinical presentations such as a pure motor syndrome, a sensory ataxic variant, a mononeuritis multiplex pattern, relapsing GBS, and a paraparetic subtype. Each of the acute and the subtypes have different, more or less distinct, electrophysiologic and pathological findings. Instructive patient stories are presented together with there electrophysiologic and biopsy findings.

Antibodies against Helicobacter pylori were detected in the cerebrospinal fluid obtained from patients with Guillain-Barré syndrome

We examined the antibodies against Helicobacter pylori proteins in the cerebrospinal fluid (CSF) of 7 patients with Guillain-Barré syndrome (GBS). Crude H. pylori antigens, fractionated heat shock protein (HSP), and urease B (UB) from H. pylori antigens were separated by SDS-PAGE. With Western blot analysis, four of seven CSF samples had several IgG antibodies against H. pylori proteins, including HSP and UB. No cross reactivity against Campylobacter jejuni was observed. These antibodies may be involved in the immune responses of patients with GBS.

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.

Electrophysiologic assessment of acute polyradiculoneuropathy in dogs: comparison with Guillain-Barré syndrome in people

Electrophysiologic investigations of motor and sensory nerve as well as ventral nerve root function were performed on 12 dogs with suspected acute canine polyradiculoneuropathy (ACP) at different stages and with different severity of disease. The most reliable electrophysiologic indicators of ACP were electromyographic changes (occurring in 100% of affected dogs), significantly decreased compound muscle action potential amplitudes (in 75, 90, and 100% of affected dogs at all sites along the sciatic/tibial, radial, and ulnar nerves, respectively), increased minimum F-wave latencies (67%), increased F ratios (92%), and decreased F-wave amplitudes (67%). These findings suggest that ACP represents a peripheral motor axonopathy, with demyelination and axonal involvement also occurring in ventral nerve roots. Evidence of peripheral demyelination was present in some dogs although it was overshadowed by the prominent axonopathy. ACP more closely resembles the acute axonal or intermediate forms of Guillain-Barré syndrome in people.

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.