Bacterial infections in Guillain-Barré and Fisher syndromes

Pragmatic guide to peripheral nerve disease and the role of clinical biomarkers

In clinical neurology practice, there are few sensitive, specific and responsive serological biomarkers reflecting pathological processes affecting the peripheral nervous system. Instead, we rely on surrogate multimodality biomarkers for diagnosis and management. Correct use and interpretation of the available tests is essential to ensure that appropriate treatments are used and adjusted in a timely fashion. The incorrect application or interpretation of biomarkers can result in misdiagnosis and delays in appropriate treatment. Here, we discuss the uses and limitations of such biomarkers and discuss possible future developments.

Campylobacter Virulence Factors and Molecular Host-Pathogen Interactions

Campylobacter jejuni and Campylobacter coli can be frequently isolated from poultry and poultry-derived products, and in combination these two species cause a large portion of human bacterial gastroenteritis cases. While birds are typically colonized by these Campylobacter species without clinical symptoms, in humans they cause (foodborne) infections at high frequencies, estimated to cost billions of dollars worldwide every year. The clinical outcome of Campylobacter infections comprises malaise, diarrhea, abdominal pain and fever. Symptoms may continue for up to two weeks and are generally self-limiting, though occasionally the disease can be more severe or result in post-infection sequelae. The virulence properties of these pathogens have been best-characterized for C. jejuni, and their actions are reviewed here. Various virulence-associated bacterial determinants include the flagellum, numerous flagellar secreted factors, protein adhesins, cytolethal distending toxin (CDT), lipooligosaccharide (LOS), serine protease HtrA and others. These factors are involved in several pathogenicity-linked properties that can be divided into bacterial chemotaxis, motility, attachment, invasion, survival, cellular transmigration and spread to deeper tissue. All of these steps require intimate interactions between bacteria and host cells (including immune cells), enabled by the collection of bacterial and host factors that have already been identified. The assortment of pathogenicity-associated factors now recognized for C. jejuni, their function and the proposed host cell factors that are involved in crucial steps leading to disease are discussed in detail.

What did he eat?

A 13-year-old boy reported acute horizontal binocular diplopia and headache. Ten days before these symptoms he suffered from a gastrointestinal infection. Ophthalmological examination revealed bilateral ophthalmoparesis and diffuse hyporeflexia. Magnetic resonance imaging of the brain was normal. Lumbar puncture revealed albumin-cytological dissociation. There were no anti-GQ1b antibodies, but serum anti-GM1 antibodies were detected. He received intravenous immunoglobulins and had fully recovered two weeks later. Miller Fisher syndrome and its atypical variants are uncommon in childhood; nevertheless, they should be considered in the differential diagnosis of bilateral acute ophthalmoparesis.

Blocking Thrombin Significantly Ameliorates Experimental Autoimmune Neuritis

Thrombin and its protease-activated receptor 1 (PAR1) are potentially important in peripheral nerve inflammatory diseases. We studied the role of thrombin and PAR1 in rat experimental autoimmune neuritis (EAN), a model of the human Guillain-Barré syndrome (GBS). EAN was induced by bovine peripheral myelin with complete Freund's adjuvant (CFA). Thrombin activity in the sciatic nerves, clinical scores and rotarod performance were measured. Thrombin activity in the sciatic nerve was elevated in EAN compared to CFA control rats (sham rats) (p ≤ 0.004). The effect of blocking the thrombin-PAR1 pathway was studied using the non-selective thrombin inhibitor N-Tosyl-Lys-chloromethylketone (TLCK), and the highly specific thrombin inhibitor N-alpha 2 naphtalenesulfonylglycyl 4 amidino-phenylalaninepiperidide (NAPAP). In-vitro TLCK and NAPAP significantly inhibited specific thrombin activity in EAN rats sciatics (p<0.0001 for both inhibitors). Treatment with TLCK 4.4 mg/kg and NAPAP 69.8 mg/kg significantly improved clinical and rotarod scores starting at day 12 and 13 post immunization (DPI12, DPI13) respectively (p < 0.0001) compared to the untreated EAN rats. In nerve conduction studies, distal amplitude was significantly lower in EAN compared to sham rats (0.76 ± 0.34 vs. 9.8 ± 1.2, mV, p < 0.0001). Nerve conduction velocity was impaired in EAN rats (23.6 ± 2.6 vs. sham 43 ± 4.5, m/s p = 0.01) and was normalized by TLCK (41.2 ± 7.6 m/s, p < 0.05). PAR1 histology of the sciatic node of Ranvier indicated significant structural damage in the EAN rats which was prevented by TLCK treatment. These results suggest the thrombin-PAR1 pathway as a possible target for future intervention in GBS.

A single nucleotide change in mutY increases the emergence of antibiotic-resistant Campylobacter jejuni mutants

OBJECTIVES

Mutator strains play an important role in the emergence of antibiotic-resistant bacteria. Campylobacter jejuni is a leading cause of foodborne illnesses worldwide and is increasingly resistant to clinically important antibiotics. The objective of this study was to identify the genetic basis that contributes to a mutator phenotype in Campylobacter and determine the role of this phenotype in the development of antibiotic resistance.

METHODS

A C. jejuni isolate (named CMT) showing a mutator phenotype was subjected to WGS analysis. Comparative genomics, site-specific reversion and mutation, and gene knockout were conducted to prove the mutator effect was caused by a single nucleotide change in the mutY gene of C. jejuni.

RESULTS

The C. jejuni CMT isolate showed ∼ 100-fold higher mutation frequency to ciprofloxacin than the WT strain. Under selection by ciprofloxacin, fluoroquinolone-resistant mutants emerged readily from the CMT isolate. WGS identified a single nucleotide change (G595 → T) in the mutY gene of the CMT isolate. Further experiments using defined mutant constructs proved its specific role in elevating mutation frequencies. The mutY point mutation also led to an ∼ 700-fold increase in the emergence of ampicillin-resistant mutants, indicating its broader impact on antibiotic resistance. Structural modelling suggested the G595 → T mutation probably affects the catalytic domain of MutY and consequently abolishes the anti-mutator function of this DNA repair protein.

CONCLUSIONS

The G595 → T mutation in mutY abolishes its anti-mutator function and confers a mutator phenotype in Campylobacter, promoting the emergence of antibiotic-resistant Campylobacter.

Extracellular secretion of protease HtrA from Campylobacter jejuni is highly efficient and independent of its protease activity and flagellum

The serine protease HtrA of C. jejuni has been identified as a novel secreted virulence factor which opens cell-to-cell junctions by cleaving E-cadherin. Efficient C. jejuni transmigration across polarized human epithelial cells requires the intact flagellum and HtrA; however, the mechanism of HtrA secretion into the supernatant is unknown. Here we show that HtrA secretion is highly efficient and does not require its proteolytic activity because the protease-inactive S197A mutant is secreted like wild-type HtrA. In addition, the flagellar mutants ΔflaA/B, ΔfliI, ΔflgH, ΔflhA, ΔflhB, and ΔflgS were also able to secrete HtrA in high amounts, while they were strongly attenuated in secreting the well-known invasion antigen CiaB. We also tested several culture media and cell lines of different origin such as human, mouse, hamster, dog, and chicken for their ability to influence HtrA secretion. Interestingly, HtrA was effectively secreted in the presence of most but not all cell lines and media, albeit at different levels, but secretion was significantly higher when fetal calf serum (FCS) was added. These results demonstrate that HtrA secretion by Campylobacter proceeds independent of HtrA's protease activity, the flagellum and origin of cell lines, but can be strongly enhanced by molecular compound(s) present in FCS.

The pre-synaptic motor nerve terminal as a site for antibody-mediated neurotoxicity in autoimmune neuropathies and synaptopathies

The pre-synaptic motor nerve terminal is a highly complex and dynamic compartment within the lower motor neuron responsible for converting electrical signals into secreted chemicals. This self-renewing process of synaptic transmission is accomplished by the calcium-triggered fusion of neurotransmitter-containing vesicles with the plasma membrane and the subsequent retrieval and recycling of vesicle components. Besides this conventional physiological role, the highly active process of vesicle fusion and re-uptake into endosomal sorting pathways acts as a conduit for entry of a range of substances into the intracellular compartment of the motor nerve terminal. Whilst this entry portal sub-serves many vital physiological processes, such as those mediated by neurotrophin trafficking, there is also the potential for substantial pathological consequences resulting from uptake of noxious agents, including autoantibodies, viruses and toxins. These may act locally to induce disease within the nerve terminal, or traffic beyond to the motor neuron cell body and central nervous system to exert their pathological effects. This review focuses on the recent evidence that the ganglioside-rich pre-synaptic membrane acts as a binding site for potentially neurotoxic serum autoantibodies that are present in human autoimmune motor neuropathies. Autoantibodies that bind surface antigens induce membrane lytic effects, whereas their uptake attenuates local injury and transfers any potential pathological consequences to the intracellular compartment. Herein the thesis is explored that a balance exists between local injury at the exofacial leaflet of the pre-synaptic membrane and antibody uptake, which dictates the overall level and site of motor nerve injury in this group of disorders.

[Ophthalmoplegia with bilateral mydriasis]

We report the case history of a 41-year-old patient who, following bronchial infection, presented with progressive ophthalmoplegia in both eyes, dilated pupils unresponsive to light or convergence and ataxia. The suspected diagnosis of Miller-Fisher syndrome was confirmed by the detection of anti-ganglioside GQ1b antibodies.

A novel pneumococcus with a new association

A case of severe invasive pneumococcal disease in a 68 year old female is described. She presented following a holiday in Turkey with an uncommon but well documented complication of Streptococcus pneumoniae bacteraemia; Austrian's triad of meningitis, pneumonia and endocarditis. She then progressed to develop an atypical variant of Guillain Barre syndrome, never previously documented in association with pneumococcal disease. The pneumococcus was identified as serotype 6A and genetic typing by multi-locus sequence typing showed it to be a unique genetic profile (ST4533). We hypothesise that ST4533 may have resulted from genetic re-assortment from streptococci which had colonised the patient in the United Kingdom and bacteria encountered in Turkey. The ability to associate uncommon genotypes with uncommon clinical presentations may improve understanding of the pathogenesis of this organism, and this highlights the need for international invasive pneumococcal disease surveillance.

Antibacterial activity and mechanism of action of zinc oxide nanoparticles against Campylobacter jejuni

The antibacterial effect of zinc oxide (ZnO) nanoparticles on Campylobacter jejuni was investigated for inhibition and inactivation of cell growth. The results showed that C. jejuni was extremely sensitive to treatment with ZnO nanoparticles. The MIC of ZnO nanoparticles for C. jejuni was determined to be 0.05 to 0.025 mg/ml, which is 8- to 16-fold lower than that for Salmonella enterica serovar Enteritidis and Escherichia coli O157:H7 (0.4 mg/ml). The action of ZnO nanoparticles against C. jejuni was determined to be bactericidal, not bacteriostatic. Scanning electron microscopy examination revealed that the majority of the cells transformed from spiral shapes into coccoid forms after exposure to 0.5 mg/ml of ZnO nanoparticles for 16 h, which is consistent with the morphological changes of C. jejuni under other stress conditions. These coccoid cells were found by ethidium monoazide-quantitative PCR (EMA-qPCR) to have a certain level of membrane leakage. To address the molecular basis of ZnO nanoparticle action, a large set of genes involved in cell stress response, motility, pathogenesis, and toxin production were selected for a gene expression study. Reverse transcription-quantitative PCR (RT-qPCR) showed that in response to treatment with ZnO nanoparticles, the expression levels of two oxidative stress genes (katA and ahpC) and a general stress response gene (dnaK) were increased 52-, 7-, and 17-fold, respectively. These results suggest that the antibacterial mechanism of ZnO nanoparticles is most likely due to disruption of the cell membrane and oxidative stress in Campylobacter.

Miller fisher syndrome presents as an acute voice change to hypernasal speech

The authors describe a 38-year-old man who presented with hypernasality, perioral and acroparesthesia, dyspnea, and dysphagia. Further evaluation revealed a diagnosis of Miller-Fisher syndrome (MFS). MFS is a variant of Guillain-Barré syndrome previously described in neurology and critical care journals; however, there is a paucity of work concerning this disease in the otolaryngology literature. An acute change in voice usually occurs secondary to inflammatory processes as seen after intubation and infection, but can occur as part of a more complex disease entity such as Guillain-Barré or Miller-Fisher syndrome. As such, clinicians should consider this in their evaluation of rhinolalia aperta.

Evidence for a lineage of virulent bacteriophages that target Campylobacter

Background

Our understanding of the dynamics of genome stability versus gene flux within bacteriophage lineages is limited. Recently, there has been a renewed interest in the use of bacteriophages as 'therapeutic' agents; a prerequisite for their use in such therapies is a thorough understanding of their genetic complement, genome stability and their ecology to avoid the dissemination or mobilisation of phage or bacterial virulence and toxin genes. Campylobacter, a food-borne pathogen, is one of the organisms for which the use of bacteriophage is being considered to reduce human exposure to this organism.

Results

Sequencing and genome analysis was performed for two Campylobacter bacteriophages. The genomes were extremely similar at the nucleotide level (≥ 96%) with most differences accounted for by novel insertion sequences, DNA methylases and an approximately 10 kb contiguous region of metabolic genes that were dissimilar at the sequence level but similar in gene function between the two phages. Both bacteriophages contained a large number of radical S-adenosylmethionine (SAM) genes, presumably involved in boosting host metabolism during infection, as well as evidence that many genes had been acquired from a wide range of bacterial species. Further bacteriophages, from the UK Campylobacter typing set, were screened for the presence of bacteriophage structural genes, DNA methylases, mobile genetic elements and regulatory genes identified from the genome sequences. The results indicate that many of these bacteriophages are related, with 10 out of 15 showing some relationship to the sequenced genomes.

Conclusions

Two large virulent Campylobacter bacteriophages were found to show very high levels of sequence conservation despite separation in time and place of isolation. The bacteriophages show adaptations to their host and possess genes that may enhance Campylobacter metabolism, potentially advantaging both the bacteriophage and its host. Genetic conservation has been shown to extend to other Campylobacter bacteriophages, forming a highly conserved lineage of bacteriophages that predate upon campylobacters and indicating that highly adapted bacteriophage genomes can be stable over prolonged periods of time.

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.

Immunity to Campylobacter: its role in risk assessment and epidemiology

Acquired immunity is an important factor in the epidemiology of campylobacteriosis in the developing world, apparently limiting symptomatic infection to children of less than two years. However, also in developed countries the highest incidence is observed in children under five years and the majority of Campylobacter infections are asymptomatic, which may be related to the effects of immunity and/or the ingested doses. Not accounting for immunity in epidemiological studies may lead to biased results due to the misclassification of Campylobacter-exposed but apparently healthy persons as unexposed. In risk assessment studies, health risks may be overestimated when immunity is neglected.

Lipopolysaccharide-induced inflammatory cytokine production by Schwann's cells dependent upon TLR4 expression

Signaling of Toll-like receptor-4 (TLR4) through its cognate ligand endotoxin appears critical in tissue inflammation associated with bacterial infection. We found that anti-GM1 antibody (Ab) enhances TLR4 expression in Schwann's cells (SCs) in vivo and in vitro. The anti-GM1 Ab-treated SC also showed increased release of pro-inflammation cytokines IL-1beta and TNF-alpha after incubation with lipopolysaccharide (LPS). Furthermore, down-regulation of TLR4 expression using antisense oligonucleotides targeted to TLR4 mRNA suppressed cytokine production in LPS stimulated cultures. These findings suggest that elevation of TLR4 expression increases sensitivity of SC to LPS and production of inflammatory mediators that may be responsible for peripheral nerve dysfunction.

M-cell targeting of whole killed bacteria induces protective immunity against gastrointestinal pathogens

As the majority of human pathogens infect via a mucosal surface, delivery of killed vaccines by mucosal routes could potentially improve protection against many such organisms. Our ability to develop effective killed mucosal vaccines is inhibited by a lack of adjuvants that are safe and effective in humans. The Ulex europaeus agglutinin I (UEA-I) lectin specifically binds M cells lining the murine gastrointestinal tract. We explored the potential for M-cell-targeted vaccination of whole, killed Helicobacter pylori, the main causative agent of peptic ulcer disease and gastric cancer, and Campylobacter jejuni, the most common cause of diarrhea. Oral delivery of UEA-I-agglutinated H. pylori or C. jejuni induced a significant increase in both serum and intestinal antibody levels. This elevated response (i) required the use of whole bacteria, as it did not occur with lysate; (ii) was not mediated by formation of particulate clumps, as agglutination with a lectin with a different glycan specificity had no effect; and (iii) was not due to lectin-mediated, nonspecific immunostimulatory activity, as UEA-I codelivery with nonagglutinated bacteria did not enhance the response. Vaccination with UEA-I-agglutinated, killed whole H. pylori induced a protective response against subsequent live challenge that was as effective as that induced by cholera toxin adjuvant. Moreover, vaccination against C. jejuni by this approach resulted in complete protection against challenge in almost all animals. We believe that this is the first demonstration that targeting of whole killed bacteria to mucosal M cells can induce protective immunity without the addition of an immunostimulatory adjuvant.

Functional characterization of excision repair and RecA-dependent recombinational DNA repair in Campylobacter jejuni

The presence and functionality of DNA repair mechanisms in Campylobacter jejuni are largely unknown. In silico analysis of the complete translated genome of C. jejuni NCTC 11168 suggests the presence of genes involved in methyl-directed mismatch repair (MMR), nucleotide excision repair, base excision repair (BER), and recombinational repair. To assess the functionality of these putative repair mechanisms in C. jejuni, mutS, uvrB, ung, and recA knockout mutants were constructed and analyzed for their ability to repair spontaneous point mutations, UV irradiation-induced DNA damage, and nicked DNA. Inactivation of the different putative DNA repair genes did not alter the spontaneous mutation frequency. Disruption of the UvrB and RecA orthologues, but not the putative MutS or Ung proteins, resulted in a significant reduction in viability after exposure to UV irradiation. Assays performed with uracil-containing plasmid DNA showed that the putative uracil-DNA glycosylase (Ung) protein, important for initiation of the BER pathway, is also functional in C. jejuni. Inactivation of recA also resulted in a loss of natural transformation. Overall, the data indicate that C. jejuni has multiple functional DNA repair systems that may protect against DNA damage and limit the generation of genetic diversity. On the other hand, the apparent absence of a functional MMR pathway may enhance the frequency of on-and-off switching of phase variable genes typical for C. jejuni and may contribute to the genetic heterogeneity of the C. jejuni population.

Capsule polysaccharide conjugate vaccine against diarrheal disease caused by Campylobacter jejuni

The capsule polysaccharide (CPS) of Campylobacter jejuni is one of the few identified virulence determinants of this important human pathogen. Since CPS conjugate vaccines have been so effective against other mucosal pathogens, we evaluated this approach using CPSs from two strains of C. jejuni, 81-176 (HS23 and HS36 serotype complex) and CG8486 (HS4 serotype complex). The CPSs of 81-176 and CG8486 were independently linked to the carrier protein CRM(197) by reductive amination between an aldehyde(s), strategically created at the nonreducing end of each CPS, and accessible amines of CRM(197). In both cases, the CPS:CRM(197) ratio used was 2:1 by weight. Mass spectrometry and gel electrophoresis showed that on average, each glycoconjugate preparation contained, at least in part, two to five CPSs attached to one CRM(197). When administered subcutaneously to mice, these vaccines elicited robust immune responses and significantly reduced the disease following intranasal challenge with the homologous strains of C. jejuni. The CPS(81-176)-CRM(197) vaccine also provided 100% protection against diarrhea in the New World monkey Aotus nancymaae following orogastric challenge with C. jejuni 81-176.

Campylobacter jejuni response to human mucin MUC2: modulation of colonization and pathogenicity determinants

Campylobacter jejuni is the main cause of bacterial acute gastroenteritis worldwide. In its colonization of the host intestinal tract, it encounters secreted mucins in the mucus layer and surface mucins in the epithelial cells. Mucins are complex glycoproteins that comprise the major component of mucus and give mucus its viscous consistency. MUC2 is the most abundant secreted mucin in the human intestine; it is a major chemoattractant for C. jejuni, and the bacterium binds to it. There are no studies on the transcriptional response of the bacterium to this mucin. Here, cell-culture techniques and quantitative RT-PCR were used to characterize in vitro the effects of MUC2 on C. jejuni growth and the changes in expression of 20 C. jejuni genes related to various functions. The genes encoding cytolethal distending toxin protein (cdtABC), vacuolating cytotoxin (vacB), C. jejuni lipoprotein (jlpA), Campylobacter invasion antigen (ciaB), the multidrug efflux system (cmeAB), putative mucin-degrading enzymes (cj1344c, cj0843c, cj0256 and cj1055c), flagellin A (flaA) and putative rod-shape-determining proteins (mreB and mreC) were upregulated, whereas those encoding Campylobacter adhesion fibronectin-binding protein (cadF) and sialic acid synthase (neuB1) were downregulated. These results showed that C. jejuni utilizes MUC2 as an environmental cue for the modulation of expression of genes with various functions including colonization and pathogenicity.

Comparative genomic analysis of clinical strains of Campylobacter jejuni from South Africa

BACKGROUND

Campylobacter jejuni is a common cause of acute gastroenteritis and is also associated with the post-infectious neuropathies, Guillain-Barré and Miller Fisher syndromes. In the Cape Town area of South Africa, C. jejuni strains with Penner heat-stable (HS) serotype HS:41 have been observed to be overrepresented among cases of Guillain-Barré syndrome. The present study examined the genetic content of a collection of 32 South African C. jejuni strains with different serotypes, including 13 HS:41 strains, that were recovered from patients with enteritis, Guillain-Barré or Miller Fisher syndromes. The sequence-based typing methods, multilocus sequence typing and DNA microarrays, were employed to potentially identify distinguishing features within the genomes of these C. jejuni strains with various disease outcomes.

METHODOLOGY/PRINCIPAL FINDINGS

Comparative genomic analyses demonstrated that the HS:41 South African strains were clearly distinct from the other South African strains. Further DNA microarray analysis demonstrated that the HS:41 strains from South African patients with the Guillain-Barré syndrome or enteritis were highly similar in gene content. Interestingly, the South African HS:41 strains were distinct in gene content when compared to HS:41 strains from other geographical locations due to the presence of genomic islands, referred to as Campylobacter jejuni integrated elements (CJIEs). Only the integrated element CJIE1, a Campylobacter Mu-like prophage, was present in the South African HS:41 strains whereas this element was absent in two closely-related HS:41 strains from Mexico. A more distantly-related HS:41 strain from Canada possessed both integrated elements CJIE1 and CJIE2.

CONCLUSION/SIGNIFICANCE

These findings demonstrate that CJIEs may contribute to the differentiation of closely-related C. jejuni strains. In addition, the presence of bacteriophage-related genes in CJIE1 may contribute to the genomic diversity of C. jejuni strains. This comparative genomic analysis of C. jejuni provides fundamental information that potentially could lead to improved methods for analyzing the epidemiology of disease outbreaks.

Bickerstaff's brainstem encephalitis and Fisher syndrome form a continuous spectrum: clinical analysis of 581 cases

Whether Bickerstaff's brainstem encephalitis (BBE) is a distinct disease or a subtype of Fisher syndrome (FS) is unclear as there have been no clinical studies with sufficiently large numbers of patients with FS or BBE. Our aim was to clarify the nosological relationship. Medical records of patients suffering acute ophthalmoplegia and ataxia within four weeks of onset were reviewed. BBE was the diagnosis for patients with impaired consciousness, FS for those with clear consciousness and areflexia. Clinical features, neuroimages, and laboratory findings were analyzed. Patients were grouped as having BBE (n = 53), FS (n = 466), or as unclassified (n = 62). The BBE and FS groups had similar features; positive serum anti-GQ1b IgG antibody (68 % versus 83 %), antecedent Campylobacter jejuni infection (23 % versus 21 %), CSF albuminocytological dissociation (46 % versus 76 %), brain MRI abnormality (11 % versus 2 %), and abnormal EEG findings (57 % versus 25 %). BBE (n = 4) and FS (n = 28) subgroups underwent detailed electrophysiological testing. Both groups frequently showed absent soleus H-reflexes, but normal sensory nerve conduction (75 % versus 74 %) and a 1-Hz power spectrum peak on postural body sway analysis (67 % versus 72 %). Common autoantibodies, antecedent infections, and MRI and neurophysiological results found in this large study offer conclusive evidence that Bickerstaff's brainstem encephalitis and Fisher syndrome form a continuous spectrum with variable CNS and PNS involvement.

Gangliosides as targets for autoimmune injury to the nervous system

Immune responses directed towards gangliosides and their microbial mimics are important mediators of several subtypes of acute post-infectious autoimmune neuropathy, collectively referred to as the Guillain-Barré syndromes. In this diverse group of paralytic syndromes, the immunopathology is in a proportion of cases characterised by anti-ganglioside antibody deposits, accompanied by inflammatory destruction of both axonal and glial components within the PNS. By gaining an understanding of the immunological mechanisms underlying these pathological pathways, it should be possible to select the correct targets for therapeutic intervention. Recent years has seen particular progress in our understanding of the basis for, and immunological consequences of molecular mimicry between gangliosides and microbial glycans, the relationships between ganglioside antibody specificity and different clinical phenotypes of GBS, the pathological basis for antibody-mediated nerve injury and the testing of intervention strategies in pre-clinical models. The focus of this mini-review is to provide a brief background to this field, summarise a selection of recent highlights focused on our own research, identify areas of outstanding knowledge and present data that supports novel therapeutic approaches based on the latest experimental findings.

Novel insight in the association between salmonellosis or campylobacteriosis and chronic illness, and the role of host genetics in susceptibility to these diseases

We studied the role of host genetics in the susceptibility to severe Salmonella and Campylobacter infections and chronic sequelae of these infections. Participants of a previous case-control study were sent a buccal swab kit and a questionnaire about occurrence of chronic sequelae. Single nucleotide polymorphisms (SNPs) in the TLR4 (rs4986790), IFNG (rs2430561 and rs1861493), STAT1 (rs1914408), IL1B (rs16944), NRAMP (SLC11A1 rs2276631), JUN (rs11688) and VDR (rs10735810) genes were determined. In total, 687 controls, 457 Campylobacter cases and 193 Salmonella cases participated. None of the SNPs were associated with Campylobacter or Salmonella infections. None of the participants developed Guillain-Barré, Miller-Fisher or Reiter's syndrome. Reactive arthritis occurred in 5% and 2% of cases and controls, respectively. Campylobacter cases more frequently experienced gastroenteritis episodes than controls. Campylobacter or Salmonella infection in women, use of proton pump inhibitors and an SNP in the IFNG gene were independent risk factors for reactive arthritis. Another SNP in the IFNG gene and use of proton pump inhibitors were risk factors for recurrent episodes of gastroenteritis. In conclusion, reactive arthritis and recurrent gastroenteritis episodes are common after infection and host genetic factors play a role in susceptibility to these long-term health effects.

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.