Project description:BackgroundCampylobacter jejuni is the predominant antecedent infection in Guillain-Barré syndrome (GBS). Molecular mimicry and cross-reactive immune responses to C. jejuni lipo-oligosaccharides (LOS) precipitate the development of GBS, although this mechanism has not been established in patients from developing countries. We determined the carbohydrate mimicry between C. jejuni LOS and gangliosides, and the cross-reactive antibody response in patients with GBS in Bangladesh.MethodologySera from 97 GBS patients, and 120 neurological and family controls were tested for antibody reactivity against LOS from C. jejuni isolates from GBS patients in Bangladesh (BD-07, BD-39, BD-10, BD-67 and BD-94) by enzyme-linked immunosorbent assay (ELISA). Cross-reactivity to LOS was determined by ELISA. The LOS outer core structures of C. jejuni strains associated with GBS/MFS were determined by mass spectrometry.Principle findingsIgG antibodies to LOS from C. jejuni BD-07, BD-39, BD-10, and BD-67 IgG antibodies were found in serum from 56%, 58%, 14% and 15% of GBS patients respectively, as compared to very low frequency (<3%) in controls (p<0.001). Monoclonal antibodies specific for GM1 and GD1a reacted strongly with LOS from the C. jejuni strains (BD-07 and BD-39). Mass spectrometry analysis confirmed the presence of GM1 and GD1a carbohydrate mimics in the LOS from C. jejuni BD-07 and BD-39. Both BD-10 and BD-67 express the same LOS outer core, which appears to be a novel structure displaying GA2 and GD3 mimicry. Up to 90-100% of serum reactivity to gangliosides in two patients (DK-07 and DK-39) was inhibited by 50 µg/ml of LOS from the autologous C. jejuni isolates. However, patient DK-07 developed an anti-GD1a immune response while patient DK-39 developed an anti-GM1 immune response.ConclusionCarbohydrate mimicry between C. jejuni LOS and gangliosides, and cross-reactive serum antibody precipitate the majority of GBS cases in Bangladesh.
Project description:Molecular mimicry between microbial and self-components is postulated as the mechanism that accounts for the antigen and tissue specificity of immune responses in postinfectious autoimmune diseases. Little direct evidence exists, and research in this area has focused principally on T cell-mediated, antipeptide responses, rather than on humoral responses to carbohydrate structures. Guillain-Barré syndrome, the most frequent cause of acute neuromuscular paralysis, occurs 1-2 wk after various infections, in particular, Campylobacter jejuni enteritis. Carbohydrate mimicry [Galbeta1-3GalNAcbeta1-4(NeuAcalpha2-3)Galbeta1-] between the bacterial lipooligosaccharide and human GM1 ganglioside is seen as having relevance to the pathogenesis of Guillain-Barré syndrome, and conclusive evidence is reported here. On sensitization with C. jejuni lipooligosaccharide, rabbits developed anti-GM1 IgG antibody and flaccid limb weakness. Paralyzed rabbits had pathological changes in their peripheral nerves identical with those present in Guillain-Barré syndrome. Immunization of mice with the lipooligosaccharide generated a mAb that reacted with GM1 and bound to human peripheral nerves. The mAb and anti-GM1 IgG from patients with Guillain-Barré syndrome did not induce paralysis but blocked muscle action potentials in a muscle-spinal cord coculture, indicating that anti-GM1 antibody can cause muscle weakness. These findings show that carbohydrate mimicry is an important cause of autoimmune neuropathy.
Project description:Gangliosides are a class of glycosphingolipid molecules that are highly enriched in cellular membranes of the nervous system. The gangliosides associated with autoimmune diseases of the nervous system are mainly GM1, GD1a, GalNAc-GD1a, GM1b, GD3, CD1b, GT1a, and GQ1b. Multiple antibodies recognizing gangliosides are associated with some acute or chronic peripheral neuropathies, especially Guillain-Barré syndrome (GBS) and its clinical variants. Antibodies binding to gangliosides can activate complement system and recruit macrophages on the axolemma at the nodes of Ranvier of motor fibers, which are found in the course of GBS, causing axonal degeneration and reversible conduction block or conduction failure. Testing of anti-gangliosides autoantibodies is helpful for diagnosis of autoimmune peripheral neuropathies or support the diagnosis of the subtypes. These anti-gangliosides antibodies are usually detected by several qualitative or quantitative methods, particularly enzyme-linked immunosorbent assay (ELISA) and immunodot assays, which have been commercialized or established in-house worldwide. Herein, we introduce the methods and clinical applications of these assays in the diagnosis of autoimmune peripheral neuropathies. Anti-gangliosides antibodies are diagnostic markers of GBS subtypes. We use GBS as an example to explain the role of anti-gangliosides antibodies in the pathogenesis and diagnostic classification of neuropathies.
Project description:Guillain-Barré syndrome (GBS) and transverse myelitis (TM) both represent immunologically mediated polyneuropathies of major clinical importance. Both are thought to have a genetic predisposition, but as of yet no specific genetic risk loci have been clearly defined. Both are considered autoimmune, but again the etiologies remain enigmatic. Both may be induced via molecular mimicry, particularly from infectious agents and vaccines, but clearly host factor and co-founding host responses will modulate disease susceptibility and natural history. GBS is an acute inflammatory immune-mediated polyradiculoneuropathy characterized by tingling, progressive weakness, autonomic dysfunction, and pain. Immune injury specifically takes place at the myelin sheath and related Schwann-cell components in acute inflammatory demyelinating polyneuropathy, whereas in acute motor axonal neuropathy membranes on the nerve axon (the axolemma) are the primary target for immune-related injury. Outbreaks of GBS have been reported, most frequently related to Campylobacter jejuni infection, however, other agents such as Zika Virus have been strongly associated. Patients with GBS related to infections frequently produce antibodies against human peripheral nerve gangliosides. In contrast, TM is an inflammatory disorder characterized by acute or subacute motor, sensory, and autonomic spinal cord dysfunction. There is interruption of ascending and descending neuroanatomical pathways on the transverse plane of the spinal cord similar to GBS. It has been suggested to be triggered by infectious agents and molecular mimicry. In this review, we will focus on the putative role of infectious agents as triggering factors of GBS and TM.
Project description:An outbreak of Guillain-Barré syndrome (GBS), subsequent to Campylobacter jejuni enteritis, occurred in China in 2007. Serum anti-ganglioside antibodies were measured in GBS patients and controls. Genome sequencing was used to determine the phylogenetic relationship among three C. jejuni strains from a patient with GBS (ICDCCJ07001), a patient with gastroenteritis (ICDCCJ07002) and a healthy carrier (ICDCCJ07004), which were all associated with the outbreak. The ganglioside-like structures of the lipo-oligosaccharides of these strains were determined by mass spectrometry. Seventeen (53%) of the GBS patients had anti-GT1a IgG antibodies. GT1a mimicry was found in the lipo-oligosaccharides of strain ICDCCJ07002 and ICDCCJ07004; but a combination of GM3/GD3 mimics was observed in ICDCCJ07001, although this patient had anti-GT1a IgG antibodies. A single-base deletion in a glycosyltransferase gene caused the absence of GT1a mimicry in ICDCCJ07001. The phylogenetic tree showed that ICDCCJ07002 and ICDCCJ07004 were genetically closer to each other than to ICDCCJ07001. C. jejuni, bearing a GT1a-like lipo-oligosaccharide, might have caused the GBS outbreak and the loss of GT1a mimicry may have helped ICDCCJ07001 to survive in the host.
Project description:Severe acute respiratory syndrome-related coronavirus 2 infection has been associated with Guillain-Barré syndrome. We investigated here the potential mechanism underlying the virus-induced damage of the peripheral nervous systems by searching the viral amino acid sequence for peptides common to human autoantigens associated with immune-mediated polyneuropathies. Our results show molecular mimicry between the virus and human heat shock proteins 90 and 60, which are associated with Guillain-Barré syndrome and other autoimmune diseases. Crucially, the shared peptides are embedded in immunoreactive epitopes that have been experimentally validated in the human host.
Project description:The neurological complications of infection by the mosquito-borne Zika virus (ZIKV) include Guillain-Barré syndrome (GBS), an acute inflammatory demyelinating polyneuritis. GBS was first associated with recent ZIKV epidemics caused by the emergence of the ZIKV Asian lineage in South Pacific. Here, we hypothesize that ZIKV-associated GBS relates to a molecular mimicry between viral envelope E (E) protein and neural proteins involved in GBS. The analysis of the ZIKV epidemic strains showed that the glycan loop (GL) region of the E protein includes an IVNDT motif which is conserved in voltage-dependent L-type calcium channel subunit alpha-1C (Cav1.2) and Heat Shock 70 kDa protein 12A (HSP70 12A). Both VSCC-alpha 1C and HSP70 12A belong to protein families which have been associated with neurological autoimmune diseases in central nervous system. The purpose of our in silico analysis is to point out that IVNDT motif of ZIKV E-GL region should be taken in consideration for the development of safe and effective anti-Zika vaccines by precluding the possibility of adverse neurologic events including autoimmune diseases such as GBS through a potent mimicry with Heat Shock 70 kDa protein 12A (HSP70 12A).
Project description:Molecular mimicry of Campylobacter jejuni lipo-oligosaccharides (LOS) with gangliosides in nervous tissue is considered to induce cross-reactive antibodies that lead to Guillain-Barre syndrome (GBS), an acute polyneuropathy. To determine whether specific bacterial genes are crucial for the biosynthesis of ganglioside-like structures and the induction of anti-ganglioside antibodies, we characterized the C. jejuni LOS biosynthesis gene locus in GBS-associated and control strains. We demonstrated that specific types of the LOS biosynthesis gene locus are associated with GBS and with the expression of ganglioside-mimicking structures. Campylobacter knockout mutants of 2 potential GBS marker genes, both involved in LOS sialylation, expressed truncated LOS structures without sialic acid, showed reduced reactivity with GBS patient serum, and failed to induce an anti-ganglioside antibody response in mice. We demonstrate, for the first time, to our knowledge, that specific bacterial genes are crucial for the induction of anti-ganglioside antibodies.
Project description:IntroductionWe present a rare case of acute immune-mediated polyradiculoneuritis, a Guillain-Barré Syndrome (GBS) variant, manifesting as ophthalmoparesis-ataxia, facial diplegia, and acute bulbar palsy, accompanied by a unique autoimmune profile.Clinical caseA 75-year-old female developed rapidly progressive symptoms, including bilateral non-reactive mydriasis, ptosis, complete ophthalmoplegia, bilateral facial weakness, tongue immobility, palatal paralysis, limb dysmetria, ataxia, and brisk generalized tendon reflexes, all while maintaining a preserved mental state. Symptoms emerged 10 days after a probable gastrointestinal infection. Severe bulbar dysfunction necessitated orotracheal intubation and a tracheotomy. Extensive cranial nerve involvement initially suggested a brainstem lesion, with oculomotor and acute bulbar palsy as prominent signs. However, brainstem and spinal magnetic resonance imaging along with cerebrospinal fluid analysis yielded negative results. Electromyography reveled a sensorimotor demyelinating polyradiculoneuropathy, and serum testing identified IgG antibodies targeting multiple gangliosides, including the disialosyl group and terminal NeuNAc(α2-3)Gal. Treatment with intravenous immunoglobulin (IVIG) led to gradual clinical improvement.ConclusionsThis case highlights a rare and severe GBS phenotype characterized by reactivity to multiple gangliosides. It highlights the role of shared ganglioside epitopes in antibody-mediated neurological damage and expands the clinical spectrum of GBS variants.