The Guillain-Barré syndrome: a true case of molecular mimicry

Reactivity against complementary proteinase-3 is not increased in patients with PR3-ANCA-associated vasculitis

The etiology of anti-neutrophil cytoplasmic antibodies (ANCA) associated vasculitides (AAV) is unknown, but the association between infections and autoimmunity has been studied extensively. In 2004, a novel theory was proposed that could link infection and autoimmunity. This ‘theory of autoantigen complementarity’ was based on the serendipitous finding of antibodies against complementary-PR3 (cPR3) in patients with PR3-ANCA-associated vasculitis. cPR3 demonstrated homology to several bacterial proteins, and it was hypothesized that PR3-ANCA develop in response to anti-cPR3 antibodies, as a consequence of the anti-idiotypic network. These data have not been confirmed in other patient cohorts. We investigated the presence of anti-cPR3 antibodies in a Dutch cohort of PR3-ANCA-associated vasculitis patients. Anti-cPR3 reactivity was determined in serum using ELISA. Two separate batches of cPR3 were used to determine reactivity in two separate cohorts of PR3-ANCA-associated vasculitis patients. We found that anti-cPR3-reactivity was not increased in our PR3-ANCA-associated vasculitis patients, in comparison to control groups. Further research will be necessary to prove the concept of autoantigen complementarity in autoimmune diseases.

Discrimination of major capsular types of Campylobacter jejuni by multiplex PCR

The polysaccharide capsule (CPS) of Campylobacter jejuni is the major serodeterminant of the Penner serotyping scheme. There are 47 Penner serotypes of C. jejuni, 22 of which fall into complexes of related serotypes. A multiplex PCR method for determination of capsule types of Campylobacter jejuni which is simpler and more affordable than classical Penner typing was developed. Primers specific for each capsule type were designed on the basis of a database of gene sequences from the variable capsule loci of 8 strains of major serotypes sequenced in this study and 10 published sequences of other serotypes. DNA sequence analysis revealed a mosaic nature of the capsule loci, suggesting reassortment of genes by horizontal transfer, and demonstrated a high degree of conservation of genes within Penner complexes. The multiplex PCR can distinguish 17 individual serotypes in two PCRs with sensitivities and specificities ranging from 90 to 100% using 244 strains of known Penner type.

Guillain-barré syndrome animal model: the first proof of molecular mimicry in human autoimmune disorder

Molecular mimicry between self and microbial components has been proposed as the pathogenic mechanism of autoimmune diseases, and this hypothesis is proven in Guillain-Barré syndrome. Guillain-Barré syndrome, the most frequent cause of acute neuromuscular paralysis, sometimes occurs after Campylobacter jejuni enteritis. Gangliosides are predominantly cell-surface glycolipids highly expressed in nervous tissue, whilst lipo-oligosaccharides are major components of the Gram-negative bacterium C. jejuni outer membrane. IgG autoantibodies to GM1 ganglioside were found in the sera from patients with Guillain-Barré syndrome. Molecular mimicry was demonstrated between GM1 and lipo-oligosaccharide of C. jejuni isolated from the patients. Disease models by sensitization of rabbits with GM1 and C. jejuni lipo-oligosaccharide were established. Guillain-Barré syndrome provided the first verification that an autoimmune disease is triggered by molecular mimicry. Its disease models are helpful to further understand the molecular pathogenesis as well as to develop new treatments in Guillain-Barré syndrome.

Temperature-dependent phenotypic variation of Campylobacter jejuni lipooligosaccharides

BACKGROUND

Campylobacter jejuni is a major bacterial cause of food-borne enteritis, and its lipooligosaccharide (LOS) plays an initiating role in the development of the autoimmune neuropathy, Guillain-Barré syndrome, by induction of anti-neural cross-reactive antibodies through ganglioside molecular mimicry.

RESULTS

Herein we describe the existence and heterogeneity of multiple LOS forms in C. jejuni strains of human and chicken origin grown at 37 °C and 42 °C, respectively, as determined on sodium dodecyl sulphate-polyacrylamide electrophoresis gels with carbohydrate-specific silver staining and blotting with anti-ganglioside ligands, and confirmed by nuclear magnetic resonance (NMR) spectroscopy. The C. jejuni NCTC 11168 original isolate (11168-O) was compared to its genome-sequenced variant (11168-GS), and both were found to have a lower-M(r) LOS form, which was different in size and structure to the previously characterized higher-M(r) form bearing GM₁ mimicry. The lower-M(r) form production was found to be dependent on the growth temperature as the production of this form increased from ~5%, observed at 37 °C to ~35% at 42 °C. The structure of the lower-M(r) form contained a β-D-Gal-(1→3)-β-D-GalNAc disaccharide moiety which is consistent with the termini of the GM₁, asialo-GM₁, GD₁, GT₁ and GQ₁ gangliosides, however, it did not display GM₁ mimicry as assessed in blotting studies but was shown in NMR to resemble asialo-GM₁. The production of multiple LOS forms and lack of GM1 mimicry was not a result of phase variation in the genes tested of NCTC 11168 and was also observed in most of the human and chicken isolates of C. jejuni tested.

CONCLUSION

The presence of differing amounts of LOS forms at 37 and 42 °C, and the variety of forms observed in different strains, indicate that LOS form variation may play a role in an adaptive mechanism or a stress response of the bacterium during the colonization of different hosts.

Transient immunosuppression: a bridge between infection and the atypical autoimmunity of Guillain-Barré syndrome?

Guillain-Barré syndrome (GBS) is an acute, usually monophasic, disorder of the peripheral nervous system that is assumed to be of immune-mediated pathogenesis. However, several clinical features and experimental findings of GBS are uncharacteristic for an immune-mediated disorder and set this condition apart from other disorders with a putative immune-mediated pathogenesis. These features include, among others, the monophasic nature of GBS, the lack of response to immunosuppressive (unlike immunomodulatory) therapy, the absence of a typical association with immunogenetic background and the inability to establish a valid and relevant animal model. We suggest a comprehensive hypothesis for the pathogenesis of GBS that is based on the assumption that the condition is due to a transient (or occasionally chronic) immune deficiency, as in most cases GBS follows an infection with pathogens known to induce immunosuppression. Such infections may be followed by breakdown of immune tolerance and induction of an immune attack on peripheral nerves. Mounting of the immune-mediated assault might be triggered either by the same infective pathogen or by secondary infection. Clearance of the infection and resumption of a normal immune response and tolerance eventually terminate the immune-mediated damage to the peripheral nerves and enable recovery. This hypothesis assumes that the entire sequence of events that culminates in GBS is due to transient exogenous factors and excludes a significant role for inherent host susceptibility, which explains the monophasic nature of the disorder.

Temporal association of Streptococcus, Staphylococcus, and parainfluenza pediatric hospitalizations and hospitalized cases of Henoch-Schönlein purpura

OBJECTIVE

To determine if hospitalizations for specific infectious exposures are associated with hospital admissions for Henoch-Schönlein purpura (HSP).

METHODS

We conducted a retrospective cohort study using administrative data of children admitted to 40 children's hospitals between January 1, 2002, and December 31, 2008. We examined the association of standardized rates of group A ß-hemolytic Streptococcus (GABS), Staphylococcus aureus, parainfluenza, influenza, adenovirus, and respiratory syncytial virus (RSV)-associated hospital admissions with standardized rates of HSP hospital admissions on a month by month basis using autoregressive moving average process models to account for temporal autocorrelation and clustering by hospital.

RESULTS

Among the 3,132 admissions for HSP observed over the 7-year study period, hospital admissions were most frequent September through April, but with substantial variability between hospitals for each month. Accounting for these month by month differences within each hospital, the rate of HSP admissions in a given month increased significantly as the standardized rates of GABS (p = 0.01), S. aureus (p < 0.01), and parainfluenza (p = 0.03) admissions increased.

CONCLUSION

Our results demonstrate a local month by month temporal association between hospitalization for GABS, S. aureus, and parainfluenza and hospitalization for HSP. Future investigations will be required to determine causality.

Mechanisms underlying autoimmune synaptic encephalitis leading to disorders of memory, behavior and cognition: insights from molecular, cellular and synaptic studies

Recently, several novel, potentially lethal and treatment-responsive syndromes that affect hippocampal and cortical function have been shown to be associated with auto-antibodies against synaptic antigens, notably glutamate or GABA-B receptors. Patients with these auto-antibodies, sometimes associated with teratomas and other neoplasms, present with psychiatric symptoms, seizures, memory deficits and decreased levels of consciousness. These symptoms often improve dramatically after immunotherapy or tumor resection. Here we review studies of the cellular and synaptic effects of these antibodies in hippocampal neurons in vitro and preliminary work in rodent models. Our work suggests that patient antibodies lead to rapid and reversible removal of neurotransmitter receptors from synaptic sites, leading to changes in synaptic and circuit function that in turn are likely to lead to behavioral deficits. We also discuss several of the many questions raised by these and related disorders. Determining the mechanisms underlying these novel anti-neurotransmitter receptor encephalopathies will provide insights into the cellular and synaptic bases of the memory and cognitive deficits that are hallmarks of these disorders, and potentially suggest avenues for therapeutic intervention.

Cytochrome P450 2D6 as a model antigen

Cytochrome P450 2D6 (CYP2D6) has been identified as the major autoantigen in type 2 autoimmune hepatitis (AIH). However, because of a lack of appropriate animal models, the etiology of AIH is still poorly understood. We generated a mouse model for AIH using the human CYP2D6 as a triggering molecule for autoimmunity. We infected wild-type FVB mice with an adenovirus expressing human CYP2D6 (Ad-2D6) to break self-tolerance to the mouse CYP2D6 homologues. Ad-2D6-infected mice showed persistent features of liver damage including hepatic fibrosis, cellular infiltrations, focal-to-confluent necrosis and generation of anti-CYP2D6 antibodies, which predominantly recognized the identical immunodominant epitope recognized by LKM-1 antibodies from AIH patients. Interestingly, Ad-2D6 infection of transgenic mice expressing the human CYP2D6 (CYP2D6 mice) resulted in delayed kinetics and reduced severity of liver damage. However, the quantity and quality of anti-CYP2D6 antibodies was only moderately reduced in CYP2D6 mice. In contrast, the frequency of CYP2D6-specific CD4 and CD8 T cells was dramatically decreased in CYP2D6 mice, indicating the presence of a strong T cell tolerance to human CYP2D6 established in CYP2D6 mice, but not in wild-type mice. CYP2D6-specific T cells reacted to human CYP2D6 peptides with intermediate homology to the mouse homologues, but not to those with high homology, indicating that molecular mimicry rather than molecular identity breaks tolerance and subsequently causes severe persistent autoimmune liver damage. The CYP2D6 model provides a platform to investigate mechanisms involved in the immunopathogenesis of autoimmune-mediated chronic hepatic injury and evaluate possible ways of therapeutic interference.

Characterization of the specific interaction between sialoadhesin and sialylated Campylobacter jejuni lipooligosaccharides

In Campylobacter jejuni-induced Guillain-Barré syndrome (GBS), molecular mimicry between C. jejuni lipooligosaccharide (LOS) and host gangliosides leads to the production of cross-reactive antibodies directed against the peripheral nerves of the host. Currently, the presence of surface exposed sialylated LOS in C. jejuni is the single known bacterial pathogenesis factor associated with the development of GBS. Using a unique, well-characterized strain collection, we demonstrate that GBS-associated C. jejuni strains bind preferentially to sialoadhesin (Sn, Siglec-1, or CD169), a sialic acid receptor found on a subset of macrophages. In addition, using a whole-cell enzyme-linked immunosorbent assay (ELISA), C. jejuni strains with sialylated LOS bound exclusively to soluble Sn. Mass spectrometry revealed that binding was sialic acid-linkage specific with a preference for alpha(2,3)-linked sialic acid attached to the terminal galactose of the LOS chain as seen in the gangliosides GD1a, GM1b, and GM3. This molecular interaction was also related to functional consequences as a GBS-associated C. jejuni strain that bound Sn in a whole-cell ELISA adhered to surface-expressed Sn of Sn-transfected CHO cells but was unable to adhere to wild-type CHO cells. Moreover, a sialic acid-negative mutant of the same C. jejuni strain was unable to bind Sn-transfected CHO cells. This is the first report of the preferential binding of GBS-associated C. jejuni strains to the Sn immune receptor (P = 0.014). Moreover, because this binding is dependent on sialylated LOS, the main pathogenic factor in GBS progression, the present findings bring us closer to unraveling the mechanisms that lead to formation of cross-reactive antibodies in GBS disease.

Monospecific high-affinity and complement activating anti-GM1 antibodies are determinants in experimental axonal neuropathy

It has been difficult to replicate consistently the experimental model of axonal Guillain-Barré syndrome (GBS). We immunized rabbits with two lipo-oligosaccharides (LOS1 and LOS2) derived from the same C. jejuni strain and purified in a slightly different way. LOS1 did not contain proteins whereas several proteins were present in LOS2. In spite of a robust anti-GM1 antibody response in all animals the neuropathy developed only in rabbits immunized with LOS1. To explain this discrepancy we investigated fine specificity, affinity and ability to activate the complement of anti-GM1 antibodies. Only rabbits immunized with LOS1 showed monospecific high-affinity antibodies which activated more effectively the complement. Although it is not well understood how monospecific high-affinity antibodies are induced these are crucial for the induction of experimental axonal neuropathy. Only a strict adherence to the protocols demonstrated to be successful may guarantee the reproducibility and increase the confidence in the animal model as a reliable tool for the study of the human axonal GBS.

Host factors determine anti-GM1 response following oral challenge of chickens with Guillain-Barré syndrome derived Campylobacter jejuni strain GB11

Background

Anti-ganglioside antibodies with a pathogenic potential are present in C. jejuni-associated Guillain-Barré syndrome (GBS) patients and are probably induced by molecular mimicry. Immunization studies in rabbits and mice have demonstrated that these anti-ganglioside antibodies can be induced using purified lipo-oligosaccharides (LOS) from C. jejuni in a strong adjuvant.

Methodology/Principal Findings

To investigate whether natural colonization of chickens with a ganglioside-mimicking C. jejuni strain induces an anti-ganglioside response, and to investigate the diversity in anti-ganglioside response between and within genetically different chicken lines, we orally challenged chickens with different C. jejuni strains. Oral challenge of chickens with a C. jejuni strain from a GBS patient, containing a LOS that mimics ganglioside GM1, induced specific IgM and IgG anti-LOS and anti-GM1 antibodies. Inoculation of chickens with the Penner HS:3 serostrain, without a GM1-like structure, induced anti-LOS but no anti-ganglioside antibodies. We observed different patterns of anti-LOS/ganglioside response between and within the five strains of chickens.

Conclusions

Natural infection of chickens with C. jejuni induces anti-ganglioside antibodies. The production of antibodies is governed by both microbial and host factors.

Human gangliosides and bacterial lipo-oligosaccharides in the development of autoimmune neuropathies

Guillain-Barré syndrome (GBS), the most frequent cause of acute flaccid paralysis, can develop after infection by Campylobacter jejuni. The condition is often associated with serum anti-GM1 or anti-GD1a IgG antibodies. Gangliosides contribute to stability of paranodal junctions and ion channel clusters in myelinated nerve fibers. Autoantibodies to GM1 and GD1a disrupt lipid rafts, paranodal or nodal structures, and ion channel clusters in peripheral motor nerves. Molecular mimicry exists between GM1 and GD1a gangliosides and lipo-oligosaccharides of C. jejuni isolates from GBS patients. Sensitization of rabbits with GM1 or C. jejuni lipo-oligosaccharide produces replica of GBS. These findings provide strong evidence for carbohydrate mimicry being a cause of GBS and show the role of gangliosides in peripheral nerves.

The role of endotoxin in infection: Helicobacter pylori and Campylobacter jejuni

Both Helicobacter pylori and Campylobacter jejuni are highly prevalent Gram-negative microaerophilic bacteria which are gastrointestinal pathogens of humans; H. pylori colonizes the gastroduodenal compartment and C. jejuni the intestinal mucosa. Although H. pylori causes chronic gastric infection leading to gastritis, peptic ulcers and eventually gastric cancer while C. jejuni causes acute infection inducing diarrhoeal disease, the endotoxin molecules of both bacterial species contrastingly contribute to their pathogenesis and the autoimmune sequelae each induces. Compared with enterobacterial endotoxin, that of H. pylori has significantly lower endotoxic and immuno-activities, the molecular basis for which is the underphosphorylation and underacylation of the lipid A component that interacts with immune receptors. This induction of low immunological responsiveness by endotoxin may aid the prolongation of H. pylori infection and therefore infection chronicity. On the other hand, this contrasts with acute infection-causing C. jejuni where overt inflammation contributes to pathology and diarrhoea production, and whose endotoxin is immunologically and endotoxically active. Futhermore, both H. pylori and C. jejuni exhibit molecular mimicry in the saccharide components of their endotoxins which can induce autoreactive antibodies; H. pylori expresses mimicry of Lewis and some ABO blood group antigens, C. jejuni mimicry of gangliosides. The former has been implicated in influencing the development of inflammation and gastric atrophy (a precursor of gastic cancer), the latter is central to the development of the neurological disorder Guillain-Barré syndrome. Both diseases raise important questions concerning infection-induced autoimmunity awaiting to be addressed.

Dysregulation of germinal centres in autoimmune disease

In germinal centres, somatic hypermutation and B cell selection increase antibody affinity and specificity for the immunizing antigen, but the generation of autoreactive B cells is an inevitable by-product of this process. Here, we review the evidence that aberrant selection of these autoreactive B cells can arise from abnormalities in each of the germinal centre cellular constituents--B cells, T follicular helper cells, follicular dendritic cells and tingible body macrophages--or in the supply of antigen. As the progeny of germinal centre B cells includes long-lived plasma cells, selection of autoreactive B cells can propagate long-lived autoantibody responses and cause autoimmune diseases. Elucidation of crucial molecular signals in germinal centres has led to the identification of novel therapeutic targets.

Viral triggers for autoimmunity: is the 'glass of molecular mimicry' half full or half empty?

In this review we want to consider some of the requirements for autoimmune disease to develop and how this may be reproduced in animal models. Besides a genetic predisposition, environmental triggering factors seem to play a central role in the etiology of many autoimmune diseases. In theory, a structural similarity or identity between the host and an invading pathogen might cause the immune system of the host to react not only to the pathogen but also to self-components. However, in order for such a process of molecular mimicry to induce autoimmunity the mechanisms of maintaining tolerance or ignorance to the self-components need to be circumvented. Subsequently, in order to advance autoimmunity to overt autoimmune disease the frequency and avidity of autoaggressive lymphocytes has to be of sufficient magnitude. Intuitively, one would assume that tolerance might be stronger to identical structures than to structures that just share a certain degree of similarity. Self-reactive lymphocytes with high-avidity are more likely to be deleted or functionally silenced by central and/or peripheral tolerance mechanisms. Thus, perfect mimicry between identical structures might fail in inducing autoimmunity because of efficient tolerance mechanisms. In contrast, imperfect mimicry between similar but not identical structures might on one hand circumvent tolerance but on the other hand result in the generation of lymphocytes with only low- to intermediate avidity. Here we examine animal models that use the concept of molecular mimicry as a potential mechanism for inducing or accelerating autoimmunity. We focus on the RIP-LCMV model for type 1 diabetes and the novel cytochrome P450 2D6 (CYP2D6) model for autoimmune hepatitis, which use either identical or similar triggering and target antigens.

Pathophysiological actions of neuropathy-related anti-ganglioside antibodies at the neuromuscular junction

The outer leaflet of neuronal membranes is highly enriched in gangliosides. Therefore, specific neuronal roles have been attributed to this family of sialylated glycosphingolipids, e.g. in modulation of ion channels and transporters, neuronal interaction and recognition, temperature adaptation, Ca(2+) homeostasis, axonal growth, (para)node of Ranvier stability and synaptic transmission. Recent developmental, ageing and injury studies on transgenic mice lacking subsets of gangliosides indicate that gangliosides are involved in maintenance rather than development of the nervous system and that ganglioside family members are able to act in a mutually compensatory manner. Besides having physiological functions, gangliosides are the likely antigenic targets of autoantibodies present in Guillain-Barré syndrome (GBS), a group of neuropathies with clinical symptoms of motor- and/or sensory peripheral nerve dysfunction. Antibody binding to peripheral nerves is thought to either interfere with ganglioside function or activate complement, causing axonal damage and thereby disturbed action potential conduction. The presynaptic motor nerve terminal at the neuromuscular junction (NMJ) may be a prominent target because it is highly enriched in gangliosides and lies outside the blood-nerve barrier, allowing antibody access. The ensuing neuromuscular synaptopathy might contribute to the muscle weakness in GBS patients. Several groups, including our own, have studied the effects of anti-ganglioside antibodies in ex vivo and in vivo experimental settings at mouse NMJs. Here, after providing a background overview on ganglioside synthesis, localization and physiology, we will review those studies, which clearly show that anti-ganglioside antibodies are capable of binding to NMJs and thereby can exert a variety of pathophysiological effects. Furthermore, we will discuss the human clinical electrophysiological and histological evidence produced so far of the existence of a neuromuscular synaptopathy contributing to muscle weakness in GBS patients.

MLST clustering of Campylobacter jejuni isolates from patients with gastroenteritis, reactive arthritis and Guillain-Barré syndrome

AIMS

To determine the diversity and population structure of Campylobacter jejuni (C. jejuni) isolates from Danish patients and to examine the association between multilocus sequence typing types and different clinical symptoms including gastroenteritis (GI), Guillain-Barré syndrome (GBS) and reactive arthritis (RA).

METHODS AND RESULTS

Multilocus sequence typing (MLST) was used to characterize 122 isolates, including 18 from patients with RA and 8 from patients with GBS. The GI and RA isolates were collected in Denmark during 2002-2003 and the GBS isolates were obtained from other countries. In overall, 51 sequence types (STs) were identified within 18 clonal complexes (CCs). Of these three CCs, ST-21, ST-45 and ST-22 clonal complexes accounted for 64 percent of all isolates. The GBS isolates in this study significantly grouped into the ST-22 clonal complex, consistent with the PubMLST database isolates. There was no significant clustering of the RA isolates.

CONCLUSIONS

Isolates from Denmark were found to be highly genetically diverse. GBS isolates grouped significantly with clonal complex ST-22, but the absence of clustering of RA isolates indicated that the phylogenetic background for this sequela could not be reconstructed using variation in MLST loci. Possibly, putative RA-associated genes may vary, by recombination or expression differences, independent of MLST loci.

SIGNIFICANCE AND IMPACT OF THE STUDY

MLST typing of C. jejuni isolates from Danish patients with gastroenteritis confirmed that the diversity of clones in Denmark is comparable to that in other European countries. Furthermore, a verification of the grouping of GBS isolates compared to RA isolates provides information about evolution of the bacterial population resulting in this important sequela.

Systemic lupus erythematosus and vaccination

Patients with systemic lupus erythematosus (SLE) are frequently immunodepressed making them more vulnerable to infections. Preventive vaccination is therefore warranted but has often been withheld owing to fears of a link between infection and autoimmunity, and the possibility of inducing or exacerbating lupus after vaccination. The data published in the literature suggest that vaccination of lupus patient is safe, except for live vaccines. Their efficacy is lower than in healthy subjects but protection seems to be sufficient. But further large-scale studies are required to confirm these statements.

Antibodies to Ganglioside Complexes in Guillain-Barré Syndrome: Clinical Correlates, Fine Specificity and Complement Activation

In the Schwann cells and neuronal plasma membranes the gangliosides are organized in clusters forming complexes of gangliosides in the microdomains termed lipid rafts. We investigated frequency, clinical correlates, fine specificity and pro-inflammatory properties of antibodies to ganglioside complexes (GSCs) in a Guillain Barré syndrome (GBS) population. In 63 patients with different GBS variants we performed an ELISA for antibodies to Campylobacter Jejuni ( C. jejuni), gangliosides and GSCs. We studied the fine specificity of antibodies to GSCs by immunoabsorption study and performed a complement activation assay. Twenty-seven percent of patients had antibodies to GSCs and 71% had antibodies either to single gangliosides or to GSCs. Patients with antibodies to GSCs had more frequent involvement of cranial nerves but did not present more frequent antecedent respiratory, gastrointestinal or C. jejuni infection, did not have a preferential demyelinating or primary axonal GBS variant and did not develop greater disability at six months. The absorption study showed in 2 sera that antibodies to the complex GD1a/GD1b did not react with the gangliosides forming the complex or other single gangliosides, suggesting that antibodies to GSCs are targeted to new conformational glycoepitopes different from the ones displayed by the single gangliosides. Antibody anti-GSCs activated the complement more frequently than antibodies to single gangliosides. Complement activation indicates that antibodies to GSCs have high avidity, pro-inflammatory properties and may exert a pathogenic role in GBS.

Neuromuscular synaptic transmission in aged ganglioside-deficient mice

Gangliosides are sialylated glycosphingolipids that are present in high density on neuronal membranes, especially at synapses, where they are assumed to play functional or modulating roles. Mice lacking GM2/GD2-synthase express only the simple gangliosides GD3 and GM3 and develop progressive motor behaviour deficits upon ageing, apparently due to failing complex ganglioside-dependent maintenance and/or repair processes or, alternatively, toxic GM3/GD3 accumulation. We investigated the function of neuromuscular junctions (NMJs) of aged (>9 month-old) GM2/GD2-synthase null-mutant mice, because synaptic dysfunction might develop with age and could potentially contribute to the late-onset motor phenotype. In addition, we studied NMJs of old mice lacking GD3-synthase (expressing only O- and a-series gangliosides), which do not show an overt neurological phenotype but may develop subclinical synaptic deficits. Detailed electrophysiological analyses showed subtle changes in presynaptic neurotransmitter release. Acetylcholine release at 40 Hz nerve stimulation at aged GM2/GD2-synthase null-mutant NMJs ran down slightly more pronounced than at wild-type NMJs, and spontaneous acetylcholine release rate at GD3-synthase null-mutant NMJs was somewhat higher than at wild-type, selectively at 25 °C bath temperature. Interestingly, we observed faster kinetics of postsynaptic electrophysiological responses at aged GD3-synthase null-mutant NMJs, not previously seen by us at NMJs of young GD3-synthase null-mutants or other types of (aged or young) ganglioside-deficient mice. These kinetic changes might reflect a change in postsynaptic acetylcholine receptor behaviour. Our data indicate that it is highly unlikely that transmission failure at NMJs contributes to the progressive motor defects of aged GM2/GD2-synthase null-mutants and that, despite some kinetic changes of synaptic signals, neuromuscular transmission remains successful in aged GD3-synthase null-mutant mice. Apparently, mutual redundancy of the different gangliosides in supporting presynaptic function, as observed previously by us in young mice, remains adequate upon ageing or, alternatively, gangliosides have only relatively little direct impact on neuromuscular synaptic function, even in aged mice.

Clinical features, pathogenesis, and treatment of Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is an important cause of acute neuromuscular paralysis. Molecular mimicry and a cross-reactive immune response play a crucial part in its pathogenesis, at least in those cases with a preceding Campylobacter jejuni infection and with antibodies to gangliosides. The type of preceding infection and patient-related host factors seem to determine the form and severity of the disease. Intravenous immunoglobulin (IVIg) and plasma exchange are effective treatments in GBS; mainly for practical reasons, IVIg is the preferred treatment. Whether mildly affected patients or patients with Miller Fisher syndrome also benefit from IVIg is unclear. Despite medical treatment, GBS often remains a severe disease; 3-10% of patients die and 20% are still unable to walk after 6 months. In addition, many patients have pain and fatigue that can persist for months or years. Advances in prognostic modelling have resulted in the development of a new and simple prognostic outcome scale that might also help to guide new treatment options, particularly in patients with GBS who have a poor prognosis.

Characterization of two Campylobacter jejuni strains for use in volunteer experimental-infection studies

The development of vaccines against Campylobacter jejuni would be facilitated by the ability to perform phase II challenge studies. However, molecular mimicry of the lipooligosaccharide (LOS) of most C. jejuni strains with human gangliosides presents safety concerns about the development of Guillain-Barré syndrome. Clinical isolates of C. jejuni that appeared to lack genes for the synthesis of ganglioside mimics were identified by DNA probe analyses. Two clinical isolates from Southeast Asia (strains BH-01-0142 and CG8421) were determined to express the LOS type containing N-acetyl quinovosamine. No ganglioside structures were observed to be present in the LOSs of these strains, and pyrosequence analyses of the genomes of both strains confirmed the absence of genes involved in ganglioside mimicry. The capsule polysaccharide (CPS) of BH-01-0142 was determined to be composed of galactose (Gal), 6-deoxy-ido-heptose, and, in smaller amounts, D-glycero-D-ido-heptose, and the CPS of CG8421 was observed to contain Gal, 6-deoxy-altro-heptose, N-acetyl-glucosamine, and minor amounts of 6-deoxy-3-O-Me-altro-heptose. Both CPSs were shown to carry O-methyl-phosphoramidate. The two genomes contained strain-specific zones, some of which could be traced to a plasmid origin, and both contained a large chromosomal insertion related to the CJEI3 element of C. jejuni RM1221. The genomes of both strains shared a high degree of similarity to each other and, with the exception of the capsule locus of CG8421, to the type strain of the HS3 serotype, TGH9011.

Neuromuscular synaptic function in mice lacking major subsets of gangliosides

Gangliosides are a family of sialylated glycosphingolipids enriched in the outer leaflet of neuronal membranes, in particular at synapses. Therefore, they have been hypothesized to play a functional role in synaptic transmission. We have measured in detail the electrophysiological parameters of synaptic transmission at the neuromuscular junction (NMJ) ex vivo of a GD3-synthase knockout mouse, expressing only the O- and a-series gangliosides, as well as of a GM2/GD2-synthase*GD3-synthase double-knockout (dKO) mouse, lacking all gangliosides except GM3. No major synaptic deficits were found in either null-mutant. However, some extra degree of rundown of acetylcholine release at high intensity use was present at the dKO NMJ and a temperature-specific increase in acetylcholine release at 35 degrees C was observed in GD3-synthase knockout NMJs, compared with wild-type. These results indicate that synaptic transmission at the NMJ is not crucially dependent on the particular presence of most ganglioside family members and remains largely intact in the sole presence of GM3 ganglioside. Rather, presynaptic gangliosides appear to play a modulating role in temperature- and use-dependent fine-tuning of transmitter output.

Host-pathogen interactions in Campylobacter infections: the host perspective

Campylobacter is a major cause of acute bacterial diarrhea in humans worldwide. This study was aimed at summarizing the current understanding of host mechanisms involved in the defense against Campylobacter by evaluating data available from three sources: (i) epidemiological observations, (ii) observations of patients, and (iii) experimental observations including observations of animal models and human volunteer studies. Analysis of available data clearly indicates that an effective immune system is crucial for the host defense against Campylobacter infection. Innate, cell-mediated, and humoral immune responses are induced during Campylobacter infection, but the relative importance of these mechanisms in conferring protective immunity against reinfection is unclear. Frequent exposure to Campylobacter does lead to the induction of short-term protection against disease but most probably not against colonization. Recent progress in the development of more suitable animal models for studying Campylobacter infection has opened up possibilities to study the importance of innate and adaptive immunity during infection and in protection against reinfection. In addition, advances in genomics and proteomics technologies will enable more detailed molecular studies. Such studies combined with better integration of host and pathogen research driven by epidemiological findings may truly advance our understanding of Campylobacter infection in humans.

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.

Molecular mimicry and auto-immunity

The term "molecular mimicry" was coined by R. Damian in 1964, who was first to suggest that antigenic determinants of micro-organisms may resemble antigenic determinants of their host. Damian suggested that this similarity served as a defense mechanism of a microorganism from the host's immune system and prevented the development of immune response to the micro-organism, thereby protecting it from host defense. Years later, the term "molecular mimicry" was attributed a different meaning-namely, antigenic determinants of microorganisms might elicit an auto-immune response that harms the host. The concept of molecular mimicry is based on a structural similarity between a pathogen or metabolite and self-structures. The similarity could be expressed as shared amino acid sequences (linear or mimotope) or similar conformational structure between a pathogen and self-antigen. "Molecular mimicry" has become a very popular explanation for the frequent association of infection with auto-immune disease.

Relationship between periodontal infections and systemic disease

Oral conditions such as gingivitis and chronic periodontitis are found worldwide and are among the most prevalent microbial diseases of mankind. The cause of these common inflammatory conditions is the complex microbiota found as dental plaque, a complex microbial biofilm. Despite 3000 years of history demonstrating the influence of oral status on general health, it is only in recent decades that the association between periodontal diseases and systemic conditions such as coronary heart disease and stroke, and a higher risk of preterm low birth-weight babies, has been realised. Similarly, recognition of the threats posed by periodontal diseases to individuals with chronic diseases such as diabetes, respiratory diseases and osteoporosis is relatively recent. Despite these epidemiological associations, the mechanisms for the various relationships remain unknown. Nevertheless, a number of hypotheses have been postulated, including common susceptibility, systemic inflammation with increased circulating cytokines and mediators, direct infection and cross-reactivity or molecular mimicry between bacterial antigens and self-antigens. With respect to the latter, cross-reactive antibodies and T-cells between self heat-shock proteins (HSPs) and Porphyromonas gingivalis GroEL have been demonstrated in the peripheral blood of patients with atherosclerosis as well as in the atherosclerotic plaques themselves. In addition, P. gingivalis infection has been shown to enhance the development and progression of atherosclerosis in apoE-deficient mice. From these data, it is clear that oral infection may represent a significant risk-factor for systemic diseases, and hence the control of oral disease is essential in the prevention and management of these systemic conditions.

Validation of an ELISA for the diagnosis of recent Campylobacter infections in Guillain–Barré and reactive arthritis patients

Weeks or months following Campylobacter infection, a small proportion of infected individuals develop Guillain-Barré syndrome (GBS) or reactive arthritis (ReA). Stool culture for Campylobacter is often negative in these patients, and serology is therefore the method of choice for diagnosing a recent infection with Campylobacter. This study developed a capture ELISA system to detect anti-Campylobacter IgA and IgM antibodies indicative of a recent infection. The sensitivity of the assay was 82.0% in uncomplicated Campylobacter enteritis patients, 96.2% in GBS patients who were culture-positive for Campylobacter, and 93.1% in culture-positive ReA patients, with a specificity of 93.0%. The assay allows identification of Campylobacter infection in patients with post-infectious neurological and rheumatological complications.

Origin of ganglioside complex antibodies in Guillain-Barré syndrome

The origin of antibodies to ganglioside complexes, as new immunotargets for Guillain-Barré syndrome (GBS), is unknown. This was investigated in 21 GBS patients from which Campylobacter jejuni was isolated. Two of these patients had serum IgG to the GM1/GD1a complex and two other patients had IgG to the GQ1b/GD1a complex. These pairs of patients were clinically distinct. These antibodies all cross-reacted to lipo-oligosaccharides (LOS) from the autologous C. jejuni strain. Previous mass spectrometry studies on these LOS showed the presence of oligosaccharides with a similar structure, further supporting the hypothesis that in these patients LOS induced the ganglioside complex antibodies.

Cardiovascular and oral disease interactions: what is the evidence?

This paper reviews the evidence for the interaction of oral disease (more specifically, periodontal infections) with cardiovascular disease. Cardiovascular disease is a major cause of death worldwide, with atherosclerosis as the underlying aetiology in the vast majority of cases. The importance of the role of infection and inflammation in atherosclerosis is now widely accepted, and there has been increasing awareness that immune responses are central to atherogenesis. Chronic inflammatory periodontal diseases are among the most common chronic infections, and a number of studies have shown an association between periodontal disease and an increased risk of stroke and coronary heart disease. Although it is recognised that large-scale intervention studies are required, pathogenic mechanism studies are nevertheless required so as to establish the biological rationale. In this context, a number of hypotheses have been put forward; these include common susceptibility, inflammation via increased circulating cytokines and inflammatory mediators, direct infection of the blood vessels, and the possibility of cross-reactivity or molecular mimicry between bacterial and self-antigens. In this latter hypothesis, the progression of atherosclerosis can be explained in terms of the immune response to bacterial heat shock proteins (HSPs). Because the immune system may not be able to differentiate between self-HSP and bacterial HSP, an immune response generated by the host directed at pathogenic HSP may result in an autoimmune response to similar sequences in the host. Furthermore, endothelial cells express HSPs in atherosclerosis, and cross-reactive T cells exist in the arteries and peripheral blood of patients with atherosclerosis. Each of these hypotheses is reviewed in light of current research. It is concluded that although atherosclerotic cardiovascular disease is almost certainly a multifactorial disease, there is now strong evidence that infection and inflammation are important risk factors. As the oral cavity is one potential source of infection, it is wise to try to ensure that any oral disease is minimised. This may be of significant benefit to cardiovascular health and enables members of the oral health team to contribute to their patients' general health.

Proteomic identification of potential protein markers in cerebrospinal fluid of GBS patients

Increased protein level in the cerebrospinal fluid (CSF) is a characteristic of patients with Guillain-Barré syndrome (GBS), an acute inflammatory autoimmune disorder in the peripheral nervous system (PNS). However, the molecular mechanisms underlying the disease remain poorly understood and so far no reliable disease-related markers are available. By comparing the CSF proteome of GBS patients with control subjects suffering from other neurological disorders, it may be possible to identify proteins that involve in the disease process and thus to study the pathogenesis of GBS. We used two-dimensional difference gel electrophoresis (2D DIGE) technique, in combination with matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS), to determine the abnormal CSF proteins in GBS patients. Our data showed that the levels of six proteins and their isoforms in CSF were significantly altered in GBS patients compared with controls. Haptoglobin, apolipoprotein A-IV and PRO2044 (unnamed protein) were considerably increased in the CSF of GBS patients, whereas transthyretin, apolipoprotein E and fibrinogen were considerably decreased. We concluded that these six proteins may be involved in the pathogenesis of GBS and call for further studying the role of these proteins in the pathogenesis of the disease.

PCR-restriction fragment length polymorphism analysis of Campylobacter jejuni genes involved in lipooligosaccharide biosynthesis identifies putative molecular markers for Guillain-Barré syndrome

Molecular mimicry of Campylobacter jejuni lipooligosaccharides (LOS) by gangliosides in peripheral nerve tissue probably triggers the Guillain-Barré syndrome due to the induction of cross-reactive antibodies. PCR-restriction fragment length polymorphism analysis of C. jejuni genes involved in the biosynthesis of LOS demonstrated that specific genes were associated with the expression of ganglioside mimics and the development of neuropathy.

Recent developments in mucosal vaccines against prion diseases

Bovine spongiform encephalopathy in cattle is highly suspected to be orally transmitted to humans through contaminated food, causing new variant Creutzfeldt-Jakob disease. However, no prophylactic procedures against these diseases, such as vaccines, in particular those stimulating mucosal protective immunity, have been established. The causative agents of these diseases, termed prions, consist of the host-encoded prion protein (PrP). Therefore, prions are immunologically tolerated, inducing no host antibody responses. This immune tolerance to PrP has hampered the development of vaccines against prions. We and others recently reported that the immune tolerance could be successfully broken and mucosal immunity could be stimulated by mucosal immunization of mice with PrP fused with bacterial enterotoxin or delivered using an attenuated Salmonella strain, eliciting significantly higher immunoglobulin A and G antibody responses against PrP. In this review, we will discuss these reports.

Structural characterization of Campylobacter jejuni lipooligosaccharide outer cores associated with Guillain-Barre and Miller Fisher syndromes

Molecular mimicry between lipooligosaccharides (LOS) of Campylobacter jejuni and gangliosides in peripheral nerves plays a crucial role in the pathogenesis of C. jejuni-related Guillain-Barré syndrome (GBS). We have analyzed the LOS outer core structures of 26 C. jejuni strains associated with GBS and its variant, Miller Fisher syndrome (MFS), by capillary electrophoresis coupled with electrospray ionization mass spectrometry. Sixteen out of 22 (73%) GBS-associated and all 4 (100%) MFS-associated strains expressed LOS with ganglioside mimics. GM1a was the most prevalent ganglioside mimic in GBS-associated strains (10/22, 45%), and in eight of these strains, GM1a was found in combination with GD1a mimics. All seven strains isolated from patients with ophthalmoplegia (GBS or MFS) expressed disialylated (GD3 or GD1c) mimics. Three out of 22 GBS-associated strains (14%) did not express sialylated ganglioside mimics because their LOS locus lacked the genes necessary for sialylation. Three other strains (14%) did not express ganglioside mimics because of frameshift mutations in either the cstII sialyltransferase gene or the cgtB galactosyltransferase gene. It is not possible to determine if these mutations were already present during C. jejuni infection. This is the first report in which mass spectrometry combined with DNA sequence data were used to infer the LOS outer core structures of a large number of neuropathy-associated C. jejuni strains. We conclude that molecular mimicry between gangliosides and C. jejuni LOS is the presumable pathogenic mechanism in most cases of C. jejuni-related GBS. However, our findings suggest that in some cases, other mechanisms may play a role. Further examination of the disease etiology in these patients is mandatory.

Evolution of carbohydrate antigens--microbial forces shaping host glycomes?

Many glycans show remarkably discontinuous distribution across evolutionary lineages. These differences play major roles when organisms belonging to different lineages interact as host-pathogen or host-symbiont. Certain lineage-specific glycans have become important signals for multicellular host organisms, which use them as molecular signatures of their pathogens and symbionts through recognition by a toolkit of innate defense molecules. In turn, pathogens have evolved to exploit host lineage-specific glycans and are constantly shaping the glycomes of their hosts. These interactions take place in the face of numerous critical endogenous functions played by glycans within host organisms. Whether due to simple evolutionary divergence or adaptive changes under natural selection resulting from endogenous functional requirements, once different lineages elaborate on differential glycomes these mutual differences provide opportunities for host exploitation and/or pathogen defense between lineages. Such phylogenetic molecular recognition mechanisms will augment and likely contribute to the maintenance of lineage-specific differences in glycan repertoires.

Chemical validation of molecular mimicry: interaction of cholera toxin with Campylobacter lipooligosaccharides

It is generally believed that molecular mimicry between bacterial lipooligosaccharide (LOS) and nerve glycolipids may play an important pathogenic role in immune-mediated peripheral neuropathy. One of the putative infectious agents is Campylobacter jejuni (C. jejuni). To elucidate the structural basis for the molecular mimicry, we investigated the structure of the lipooligosaccharide (LOS) fraction of C. jejuni, strain HS19, and found that it includes at least two components, characterized as fast-and slow-moving bands (LF and LS) by thin-layer chromatography as revealed by cholera toxin B subunit (Ctxb) overlay. Structural analysis of the oligosaccharide portion of LS established that it had the following structure: Gal-GalNAc-(NeuAc)Gal-Hep-(Glc;PO(3)H)Hep-Kdo. The GM1-like epitope was validated by a terminal tetrasaccharide unit within this structure. On the other hand, analysis of LF revealed an entirely different structure: 1, 4'-bisphosphoryl glucosamine disaccharide N, N'-acylated by 3-(2-hydroxytetracosanoyloxy)octadecanoic acid at 2- and 2'-positions, which is consistent with that of lipid A. No GM1-like epitope was observed in LF. Both LS and LF interacted with Ctxb as demonstrated by TLC-overlay and sucrose density gradient centrifugation. Surprisingly, LF does not have the basic GM1 structure for interacting with Ctxb. Instead, the affinity of LF to Ctxb required that one or both of the phosphate groups be present in the glucosamine disaccharide residue because after alkaline phosphatase treatment the dephosphorylated LF was unable to bind to Ctxb. We conclude that LS is likely the component contributing to GM1-mimicry in autoimmune peripheral neuropathy and that the role of LF is not clear but may be associated with the initial activation of autoreactive T cells.

Role of B Cells in Pathogenesis of Multiple Sclerosis

Despite the current limited understanding of the etiology of multiple sclerosis (MS), genetic susceptibility and environmental influences are known driving factors. MS is considered a T-cell-mediated disease given the prevalence of T cells in plaques. Plaque formation is characteristic of this disease attributable to immune mechanisms, triggered by an autoimmune attack aimed at antigens in the myelin sheath or oligodendrocyte proteins. The attack consists of the following: The role of the B cells is twofold: first, as autoreactive B cells they produce autoantibodies, secrete cytokines, clonally replicate memory B cells, and long-living plasma cells which serve to advance the diseased state by their constant production of autoantibodies. Second, as antigen-presenting cells they activate the autoreactive T cells. For this reason, the stipulation that T cell is the cornerstone of MS must be reevaluated. Various studies on pathogenesis of MS have indicated that B cells, as the humoral component of the adaptive immune system, are active participants in pathogenesis and lesion maintenance throughout the disease process. The active role of B cells and autoantibodies makes them an encouraging therapeutic target. Advances in the understanding of B-cell development and activity would allow for an enhanced strategy in the design of autoimmune treatment. For this reason, further investigation is necessary to determine whether depletion of B cells or antibodies may restore immune function.

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.

Studies of HLA associations in male and female patients with Guillain–Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)

HLA associations are found to differ with the gender of the patient in some autoimmune diseases. Here we have investigated whether there are gender-related HLA associations in Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), both of which occur more frequently in male patients than in females. In GBS, no particular HLA associations were noted, except for a slight negative association in both males and females for carriage of HLA-DR5. In CIDP, the gene frequency and the frequency of individuals positive for HLA-DR2 were greater in female patients than female controls, although this was statistically significant only for the gene frequency. Furthermore more female CIDP patients were homozygous for DR2, than male CIDP patients, or male or female controls and patients with GBS. This suggests that sex-related factors may interact with the risk associated with carriage of HLA-DR2 for development of CIDP.

Mannose-binding lectin contributes to the severity of Guillain-Barré syndrome

In Guillain-Barré syndrome (GBS), complement activation plays a crucial role in the induction and extent of the postinfectious immune-mediated peripheral nerve damage. Mannose-binding lectin (MBL) activates the complement system via the lectin pathway after recognition of repetitive sugar groups on pathogens. We investigated whether the MBL2 genotype, serum MBL level, and MBL complex activity are associated with the development and severity of GBS. Single nucleotide polymorphisms in the promoter region (-550 H/L and -221 X/Y) and exon 1 (A/O) of the MBL2 gene were determined in 271 GBS patients and 212 healthy controls. The frequencies of the H allele, HY promoter haplotype, and HYA haplotype, which are related to high MBL activity, were all increased in GBS patients compared with healthy controls (p < or = 0.03), particularly in severely affected GBS patients (MRC-sum score < 40) (p < or = 0.02). Severe weakness was also associated with high MBL concentrations and MBL complex activity in sera from GBS patients (p < 0.01). The MBL2 B allele was associated with functional deficiency and relatively mild weakness. These results support the hypothesis that complement activation mediated by MBL contributes to the extent of nerve damage in GBS, which is codetermined by the MBL2 haplotype.

Immunization with recombinant bovine but not mouse prion protein delays the onset of disease in mice inoculated with a mouse-adapted prion

Host tolerance to endogenous prion protein (PrP) has hampered the development of prion vaccines as PrP is a major component of prions. Indeed, we show that immunization of mice with mouse recombinant PrP elicited no prophylactic effect against a mouse-adapted prion. However, interestingly, mice immunized with recombinant bovine PrP developed the disease significantly later than non-immunized mice after inoculation of a mouse prion. Sheep recombinant PrP exhibited variable prophylactic effects. Mouse recombinant PrP stimulated only very weak antibody responses. In contrast, bovine recombinant PrP was higher immunogenic and produced variable amounts of anti-mouse PrP autoantibodies. Sheep recombinant PrP was also immunogenic but produced more variable amounts of anti-PrP autoantibodies. These results might open a new way for development of prion vaccines.