Serum anti-GM2 and anti-GalNAc-GD1a IgG antibodies are biomarkers for acute canine polyradiculoneuritis.

OBJECTIVES: A previous single-country pilot study indicated serum anti-GM2 and anti-GA1 anti-glycolipid antibodies as potential biomarkers for acute canine polyradiculoneuritis. This study aims to validate these findings in a large geographically heterogenous cohort. MATERIALS AND METHODS: Sera from 175 dogs clinically diagnosed with acute canine polyradiculoneuritis, 112 dogs with other peripheral nerve, cranial nerve or neuromuscular disorders and 226 neurologically normal dogs were screened for anti-glycolipid antibodies against 11 common glycolipid targets to determine the immunoglobulin G anti-glycolipid antibodies with the highest combined sensitivity and specificity for acute canine polyradiculoneuritis. RESULTS: Anti-GM2 anti-glycolipid antibodies reached the highest combined sensitivity and specificity (sensitivity: 65.1%, 95% confidence interval 57.6 to 72.2%; specificity: 90.2%, 95% confidence interval 83.1 to 95.0%), followed by anti-GalNAc-GD1a anti-glycolipid antibodies (sensitivity: 61.7%, 95% confidence interval 54.1 to 68.9%; specificity: 89.3%, 95% confidence interval 82.0 to 94.3%) and these anti-glycolipid antibodies were frequently present concomitantly. Anti-GA1 anti-glycolipid antibodies were detected in both acute canine polyradiculoneuritis and control animals. Both for anti-GM2 and anti-GalNAc-GD1a anti-glycolipid antibodies, sex was found a significantly associated factor with a female to male odds ratio of 2.55 (1.27 to 5.31) and 3.00 (1.22 to 7.89), respectively. Anti-GalNAc-GD1a anti-glycolipid antibodies were more commonly observed in dogs unable to walk (OR 4.56, 1.56 to 14.87). CLINICAL SIGNIFICANCE: Anti-GM2 and anti-GalNAc-GD1a immunoglobulin G anti-glycolipid antibodies represent serum biomarkers for acute canine polyradiculoneuritis.

Antibodies to heteromeric glycolipid complexes in multifocal motor neuropathy.

BACKGROUND: Measurement of anti-GM1 IgM antibodies in multifocal motor neuropathy (MMN) sera is confounded by relatively low sensitivity that limits clinical usefulness. Combinatorial assay methods, in which antibodies react to heteromeric complexes of two or more glycolipids, are being increasingly applied to this area of diagnostic testing. METHODS: A newly developed combinatorial glycoarray able to identify antibodies to 45 different heteromeric glycolipid complexes and their 10 individual glycolipid components was applied to a randomly selected population of 33 MMN cases and 57 normal or disease controls. Comparison with an enzyme-linked immunosorbent assay (ELISA) was conducted for selected single glycolipids and their complexes. RESULTS: By ELISA, 22/33 MMN cases had detectable anti-GM1 IgM antibodies, whereas 19/33 MMN samples were positive for anti-GM1 antibodies by glycoarray. Analysis of variance (anova) revealed that of the 55 possible single glycolipids and their 1:1 complexes, antibodies to the GM1:galactocerebroside (GM1:GalC) complex were most significantly associated with MMN, returning 33/33 MMN samples as positive by glycoarray and 29/33 positive by ELISA. Regression analysis revealed a high correlation in absolute values between ELISA and glycoarray. Receiver operator characteristic analysis revealed insignificantly different diagnostic performance between the two methods. However, the glycoarray appeared to offer slightly improved sensitivity by identifying antibodies in four ELISA-negative samples. CONCLUSIONS: The use of combinatorial glycoarray or ELISA increased the diagnostic sensitivity of anti-glycolipid antibody testing in this cohort of MMN cases, without significantly affecting specificity, and may be a useful assay modification for routine clinical screening.

Heteromeric glycolipid complexes as modulators of autoantibody and lectin binding.

Glycolipids act as receptors for a wide range of antibodies, lectins and microbes. It has long been recognised that the local topography of glycolipids in the plasma membrane is critical to these recognition events, although the biological basis for this has been relatively under-investigated. Within the last five years, emerging evidence indicates that hetero-dimeric clusters of different glycolipids can form highly distinct and specific epitopes for antibody and lectin binding. The initial observation that these ganglioside complexes (GSC) could either dramatically enhance or equally well inhibit the binding of neuropathy sera has now been reproduced for a number of other lectins, including siglecs and bacterial toxins. Here we review the initial discovery of GSC as antibody binding domains and the subsequent studies delineating their broader functional importance. Potential mechanisms underlying these effects are considered, although much remains to be investigated and explained. However, the implications for this field are potentially widespread, ranging from glycoarray design, structural biology and membrane biophysics, through to the biological consequences of glycolipid complex organisation in plasma membranes.

Voltage-gated potassium channel-associated limbic encephalitis in the West of Scotland: case reports and literature review.

BACKGROUND AND AIMS: The syndrome of limbic encephalitis (LE) associated with antibodies against voltage-gated potassium channels (VGKC-LE) has recently been described. The number of published cases is however small. We therefore aimed to review all cases seen at our centre and compare with published cases. METHODS: Retrospective cases of VGKC-LE were identified using a questionnaire to Neurologists at the Southern General hospital, Glasgow, and by reviewing patients with a positive VGKC antibody test (2002-2007). Case-note review of identified cases and a literature review of all published cases of VGKC-LE were performed. RESULTS: Seven cases were identified (four female, age range 51-81). Patients presented sub-acutely with seizures and anterograde memory loss. Five patients had medial temporal lobe change on cranial imaging. No paraneoplastic cases were identified. 5/7 patients made some improvement with immunotherapy. In 2006, 3/18 (17%) patients with a coded discharge of encephalitis were diagnosed with VGKC-LE. The literature review revealed 40 patients with VGKC-LE. Age, gender or VGKC level did not predict likelihood for a significant recovery. Patients treated < or =5 months of symptom onset with immunotherapy were more likely to make a significant recovery (83% vs. 45%, p=0.04). CONCLUSION: VGKC-LE is being increasingly diagnosed and is best identified early and treated with immunotherapy to offer the greatest chance of recovery. This series and literature review expands the current published evidence in VGKC-LE.

Diagnosis and treatment in inflammatory neuropathies.

The inflammatory neuropathies are a large diverse group of immune-mediated neuropathies that are amenable to treatment and may be reversible. Their accurate diagnosis is essential for informing the patient of the likely course and prognosis of the disease, informing the treating physician of the appropriate therapy and informing the scientific community of the results of well-targeted, designed and performed clinical trials. With the advent of biological therapies able to manipulate the immune response more specifically, an understanding of the pathogenesis of these conditions is increasingly important. This review presents a broad overview of the pathogenesis, diagnosis and therapy of inflammatory neuropathies, concentrating on the most commonly encountered conditions.

Diagnosis and treatment in inflammatory neuropathies.

The inflammatory neuropathies are a large diverse group of immune-mediated neuropathies that are amenable to treatment and may be reversible. Their accurate diagnosis is essential for informing the patient of the likely course and prognosis of the disease, informing the treating physician of the appropriate therapy and informing the scientific community of the results of well-targeted, designed and performed clinical trials. With the advent of biological therapies able to manipulate the immune response more specifically, an understanding of the pathogenesis of these conditions is increasingly important. This review presents a broad overview of the pathogenesis, diagnosis and therapy of inflammatory neuropathies, concentrating on the most commonly encountered conditions.

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.

Patterns of Guillain-Barre syndrome in children: results from a Mexican population.

BACKGROUND: Guillain-Barré syndrome (GBS) is an acute, immune-mediated flaccid paralysis frequently associated with Campylobacter infection. Of two predominant GBS subtypes, a demyelinating subtype (acute inflammatory demyelinative polyneuropathy [AIDP]) predominates in the United States and Europe, and axonal subtype (acute motor axonal neuropathy [AMAN]) is the predominant form in China. Previous clinical studies suggested that AMAN also occurs in Mexican children. The purpose of this study was to describe the subtypes of GBS in children from Mexico City. METHODS: We prospectively studied 121 children admitted to two pediatric hospitals in Mexico City from 1996 to 2002. Clinical histories were obtained, electrophysiologic studies were performed to determine GBS subtype, and microbiologic studies were performed. RESULTS: Of the 121 children, 46 had AMAN and 32 had AIDP. The male to female ratio was 1.3 for AMAN cases (mean age = 6.3) and 3.0 for AIDP cases (mean age = 7.0). There was a strong seasonal distribution of AMAN cases in July to September. Children with AMAN, but not AIDP, had worsening of illness during hospitalization as judged by peak severity scores. Vomiting was more likely in AIDP (28.1%) vs AMAN (6.5%) (p = 0.012) and diarrhea was more common in AMAN (32.6%) than AIDP (12.5%) (p = 0.06). IgG anti-GM1 antibody titers were higher in patients with AMAN vs AIDP (p = 0.067). Anti-GD1a antibodies were equally present in both groups. Anti GQ1b titers were higher in AMAN vs AIDP (p = 0.009). Campylobacter antibody responses were positive in 44.1% of patients with AMAN and 37.0% of patients with AIDP. Twenty patients (14 = AMAN, 6 = AIDP) had positive stool cultures for C jejuni. Two serotypes, HS:19 and HS:41, accounted for 6 of 10 Campylobacter isolates available for serotyping from these cases. CONCLUSIONS: This study confirms that acute motor axonal neuropathy is an important Guillain-Barré syndrome subtype in Mexican children, is associated with diarrhea, and occurs seasonally.

Treatment for Fisher syndrome, Bickerstaff's brainstem encephalitis and related disorders.

BACKGROUND: Fisher syndrome is one of the regional variants of Guillain-Barré syndrome, characterised by impairment of eye movements (ophthalmoplegia), incoordination (ataxia) and loss of tendon reflexes (areflexia). It can occur in more limited forms, and may overlap with Guillain-Barré syndrome. A further variant is associated with upper motor neuron signs and disturbance of consciousness (Bickerstaff's brainstem encephalitis). All of these variants are associated with anti-GQ1b IgG antibodies. Intravenous immunoglobulin (IVIg) and plasma exchange are often used as treatments in this patient group. This review was undertaken to systematically assess any available randomised controlled data on acute immunomodulatory therapies in Fisher Syndrome or its variants. OBJECTIVES: To provide the best available evidence from randomised controlled trials on the role of acute immunomodulatory therapy in the treatment of Fisher Syndrome and related disorders. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Trials register (March 2004), MEDLINE (from January 1966 to November 2004), EMBASE (from January 1980 to November 2004), CINAHL (from January 1982 to November 2004) and LILACS (from January 1982 to November 2004) for randomised controlled trials, quasi-randomised trials, historically controlled studies and trials with concurrent controls. We adapted this strategy to search MEDLINE from 1966 and EMBASE from 1980 for comparative cohort studies, case-control studies and case series. SELECTION CRITERIA: All randomised and quasi-randomised controlled clinical trials (in which allocation was not random but was intended to be unbiased, e.g. alternate allocation, and non-randomised controlled studies were to have been selected. Since no such clinical trials were discovered, all retrospective case series containing five or more patients were assessed and summarised in the discussion section. DATA COLLECTION AND ANALYSIS: All studies of Fisher Syndrome and its clinical variants were scrutinised for data on patients treated with any form of acute immunotherapy. Information on the outcome was then collated and summarised. MAIN RESULTS: We found no randomised or non-randomised prospective controlled trials of immunotherapy in Fisher Syndrome or related disorders. We summarised the results of retrospective series containing five or more patients in the discussion section. AUTHORS' CONCLUSIONS: There are no randomised controlled trials of immunomodulatory therapy in Fisher Syndrome or related disorders on which to base practice.

Basic and clinical aspects of autoimmune disorders in peripheral nerves.

This presentation discusses the immunobiology of the Guillain Barré syndromes (GBS), the world's leading cause of acute autoimmune neuromuscular paralysis. By gaining an understanding of the clinical and pathophysiological pathways operating in GBS, we can hope to develop novel immunotherapies that will improve clinical outcome. Here we focus on GBS mediated by anti-ganglioside antibodies and highlight the correlations between anti-ganglioside antibody patterns and clinical phenotypes, the development of models of GBS, and the application of novel therapies based on inhibition of complement activation.

A randomized controlled trial of recombinant interferon-beta 1a in Guillain-Barré syndrome.

The authors recruited 19 nonambulant patients with Guillain-Barré syndrome into a pilot, double-blind, randomized, placebo-controlled safety trial of interferon beta 1a (IFN[beta]-1a) (Rebif). Participants received IFN[beta]-1a or placebo subcutaneously three times weekly, 22 microg for the first week and then 44 microg for up to 24 weeks, in addition to IV immunoglobulin (IVIg). IFN[beta] did not have any unexpected interaction with IVIg and there was no significant difference in rate of improvement.

Apolipoprotein E genotypes and clinical outcome in Guillain-Barré syndrome.

BACKGROUND: Polymorphism of the gene encoding the cholesterol transport protein apolipoprotein E (APOE, gene; apoE, protein), known to be involved in axonal regeneration and remyelination, influences outcome after a variety of central nervous system disorders. Apolipoprotein E gene polymorphisms could affect recovery from Guillain-Barré syndrome. OBJECTIVE: To correlate APOE genotypes with residual disability and degree of improvement in Guillain-Barré syndrome, assessed one year after presentation METHODS: 91 patients with the syndrome were recruited from southeast England and their APOE genotypes were determined. RESULTS: There were no clear differences in APOE genotype or allele frequencies when comparing the 91 patients with controls, nor when comparing 81 patients with good outcome and 10 with poor outcome. CONCLUSIONS: APOE genotype did not influence susceptibility to Guillain-Barré syndrome or recovery from it. This may be because our sample size of 91 was not sufficiently large to detect small differences in recovery associated with different APOE genotypes, or because cholesterol transportation is not a crucial rate limiting step in peripheral nerve regeneration.

Structure of Campylobacter jejuni lipopolysaccharides determines antiganglioside specificity and clinical features of Guillain-Barré and Miller Fisher patients.

Ganglioside mimicry in the lipopolysaccharide (LPS) fraction of Campylobacter jejuni isolated from Guillain-Barré syndrome (GBS) and Miller Fisher syndrome (MFS) patients was compared with isolates from patients with an uncomplicated enteritis. The antibody response to C. jejuni LPS and gangliosides in neuropathy patients and controls was compared as well. LPS from GBS and MFS-associated isolates more frequently contained ganglioside-like epitopes compared to control isolates. Almost all neuropathy patients showed a strong antibody response against LPS and multiple gangliosides in contrast to enteritis patients. Isolates from GBS patients more frequently had a GM1-like epitope than isolates from MFS patients. GQ1b-like epitopes were present in all MFS-associated isolates and was associated with anti-GQ1b antibody reactivity and the presence of oculomotor symptoms. These results demonstrate that the expression of ganglioside mimics is a risk factor for the development of post-Campylobacter neuropathy. This study provides additional evidence for the hypothesis that the LPS fraction determines the antiganglioside specificity and clinical features in post-Campylobacter neuropathy patients.

[Anti-glycolipid antibodies in the diagnosis of autoimmune neuropathies]

Recent years have seen major progress in our understanding of the clinical pathophysiology of autoimmune neuropathies particularly with the identification and analysis of antibodies to gangliosides and related glycolipids in the serum of patients. Anti-glycolipid antibodies react with epitopes on the carbohydrate region of glycolipid molecules and can be routinely measured by standard immunoassays. In multifocal motor neuropathy, IgM anti-GM1 antibodies that cross react with GD1b and asialo-GM1 are detectable in around 50p. 100 of cases. This condition may clinically resemble certain forms of lower motor neurone disease. IgM anti-GD1b antibodies are found in IgM paraproteinaemic neuropathy characterised by profound sensory ataxia. In the anti-myelin associated glycoprotein (anti-MAG) IgM paraproteinaemic neuropathy, antibodies also react with the acidic glycolipids, sulphated glucuronyl paragloboside and its higher lactosaminyl homologue (SGPG and SGPLG). Thus a variety of chronic syndromes can be defined by their anti-glycolipid antibody profile. In Guillain-Barré syndrome, anti-GM1, GM1b, GD1a and GalNAc-GD1a antibodies are found in patients with acute motor axonal neuropathy (AMAN) and anti-GQ1b IgG antibodies are a very sensitive and specific marker for the Miller Fisher syndrome. Many other anti-glycolipid antibodies are being increasingly identified in other neuropathy subtypes. The article will summarise existing clinical and serological information in this field.

Anti-glycolipid antibodies in the diagnosis of autoimmune neuropathies.

Recent years have seen major progress in our understanding of the clinical pathophysiology of autoimmune neuropathies particularly with the identification and analysis of antibodies to gangliosides and related glycolipids in the serum of patients. Anti-glycolipid antibodies react with epitopes on the carbohydrate region of glycolipid molecules and can be routinely measured by standard immunoassays. In multifocal motor neuropathy, IgM anti-GM1 antibodies that cross react with GD1b and asialo-GM1 are detectable in around 50p. 100 of cases. This condition may clinically resemble certain forms of lower motor neurone disease. IgM anti-GD1b antibodies are found in IgM paraproteinaemic neuropathy characterised by profound sensory ataxia. In the anti-myelin associated glycoprotein (anti-MAG) IgM paraproteinaemic neuropathy, antibodies also react with the acidic glycolipids, sulphated glucuronyl paragloboside and its higher lactosaminyl homologue (SGPG and SGPLG). Thus a variety of chronic syndromes can be defined by their anti-glycolipid antibody profile. In Guillain-Barré syndrome, anti GM1, GM1b, GD1a and GalNAc-GD1a antibodies are found in patients with acute motor axonal neuropathy (AMAN) and anti-GQ1b IgG antibodies are a very sensitive and specific marker for the Miller Fisher syndrome. Many other anti-glycolipid antibodies are being increasingly identified in other neuropathy subtypes. The article will summarise existing clinical and serological information in this field.

Antiganglioside antibodies in acute self-limiting ataxic neuropathy: incidence and significance.

Antidisialosyl antibodies have been previously associated to chronic and acute ataxic neuropathies. We studied the presence of these antibodies in nine patients with acute self-limiting ataxic neuropathy (ASLAN) using ELISA and TLC immunodetection. One patient showed serum IgG immunoreactivity against gangliosides GD3 and GQ1b. The patient's IgG was able to bind to the nodes of Ranvier on frozen human dorsal root. Our studies confirmed that antidisialosyl reactivity is associated to ataxic neuropathy and its specific binding to the dorsal root could explain the predominant sensory involvement. Nevertheless, the low incidence of this reactivity indicates that a different pathogenic mechanism should be involved in most ASLAN patients.

Guillain-Barré syndrome serum and anti-Campylobacter antibody do not exacerbate experimental autoimmune neuritis.

To investigate whether antibodies are pathogenic in Guillain-Barré syndrome (GBS), we injected pre-treatment serum from 11 GBS patients intraperitoneally into rats in which the blood-nerve barrier had been opened by induction of mild adoptive transfer experimental autoimmune neuritis. There was no significant clinical, neurophysiological or pathological difference between rats receiving GBS serum compared with those receiving control serum, except that GBS serum caused minor excess weight loss. Murine monoclonal antibody to Campylobacter jejuni and gangliosides also did not exacerbate disease. This experiment failed to show antibody-mediated disease exacerbation and so does not support an antibody-mediated mechanism in GBS.

The clinical and laboratory features of chronic sensory ataxic neuropathy with anti-disialosyl IgM antibodies.

The clinical and laboratory phenotype of a paraproteinaemic neuropathy syndrome termed chronic sensory ataxic neuropathy with anti-disialosyl IgM antibodies is described in a series of 18 cases. Previous single case reports have outlined some features of this syndrome. All 18 cases were defined by the presence of serum IgM antibodies which react principally with NeuAc (alpha2-8)NeuAc(alpha2-3)Gal-configured disialosyl epitopes common to many gangliosides including GDlb, GD3, GTlb and GQlb. In 17 out of 18 cases, the serum contained benign IgM paraproteins, and in four of these cases at least two IgM paraproteins were present. The IgM antibodies were also cold agglutinins in 50% of cases. The clinical picture comprised a chronic neuropathy with marked sensory ataxia and areflexia, and with relatively preserved motor function in the limbs. In addition, 16 out of 18 cases had motor weakness affecting oculomotor and bulbar muscles as fixed or as relapsing-remitting features. When present in their entirety, these clinical features have been described previously under the acronym CANOMAD: chronic ataxic neuropathy, ophthalmoplegia, IgM paraprotein, cold agglutinins and disialosyl antibodies. This distribution of clinical features is reminiscent of Miller Fisher syndrome, in which acute-phase anti-disialylated ganglioside IgG antibodies are found. Clinical electrophysiology and nerve biopsy show both demyelinating and axonal features. A partial response to intravenous immunoglobulin and other treatments is reported in some cases.