Autoimmune responses in peripheral nerve

Schwann cell differentiation inhibits interferon-gamma induction of expression of major histocompatibility complex class II and intercellular adhesion molecule-1

Interferon-gamma (IFN-γ) upregulates major histocompatibility complex class II (MHC class II) antigens and intercellular adhesion molecule-1 (ICAM-1) on Schwann cells (SC) in vitro, but in nerves of animals and patients MHC class II is primarily expressed on inflammatory cells. We investigated whether SC maturation influences their expression. IFN-γ induced MHC class II and upregulated ICAM-1; the axolemma-like signal 8-bromo cyclic adenosine monophosphate (8 Br cAMP) with IFN-γ inhibited expression. Delaying addition of 8 Br cAMP to SC already exposed to IFN-γ inhibited ongoing expression; addition of IFN-γ to SC already exposed to 8 Br cAMP resulted in minimal expression. Variability of cytokine-induced MHC class II and ICAM-1 expression by SC in vivo may represent the variability of signals from axolemma.

Chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an immune disorder of the peripheral nervous system. This article highlights our current understanding of the condition along with its phenotypic variants that are encountered in clinical practice. The diagnostic evaluation of CIDP includes laboratory studies to detect associated medical conditions and electrodiagnostic studies to assess for demyelination. Current treatment options include corticosteroids, plasma exchange, and intravenous immune globulin, along with alternative therapies that may be used as corticosteroid-sparing agents or for treatment-refractory cases. Approximately 85% to 90% of patients eventually improve or stabilize with treatment, and the long-term prognosis of CIDP is favorable.

Expression of Toll-like receptors 2, 4 and 9 in patients with Guillain-Barré syndrome

OBJECTIVE

A myriad of transcription factors and inflammatory cytokines have been described to participate in the pathogenesis of Guillain-Barré syndrome (GBS). However, the innate immunity components--Toll-like receptors (TLRs)--have never been explored in this disease. We therefore investigated the expression of TLR2, 4 and 9 in the peripheral circulation of GBS patients as well as healthy controls.

METHODS

Twenty-one GBS patients and 21 healthy donors participated in this study. Peripheral blood mononuclear cells were used for mRNA and protein analysis of TLR-related molecules. Also, peripheral blood mononuclear cells from different subjects were incubated with different TLR agonists and the subsequent IFN-γ secretion was determined.

RESULTS

Expression of TLR2, 4 and 9 as well as their related signaling molecules were higher in GBS patients compared to healthy controls. Disability scores of GBS patients had a strong positive correlation with the high levels of expression of TLR2, 4 and 9.

CONCLUSIONS

The TLR signaling pathway may be involved in the pathogenesis of GBS.

Long term clinical and electrophysiological assessment of Croatian children with corticospinal tract involvement in Guillain-Barré syndrome (GBS)

Guillain-Barré syndrome (GBS) is characterized by areflexia. Hyperreflexia is reported in acute motor axonal neuropathy (AMAN). We present 16 children with GBS at the age of 14 months to 13 years. All children studied fulfilled accepted diagnostic criteria for GBS. Hyperreflexia or positive Babinski sign were obtained in all children studied during follow up. Brain and spinal cord MR scans did not reveal any significant structural and morphological abnormalities of central nervous system. The children were examined clinically and electromyoneurographically 2-5 times successively during 1-8.5 years of follow-up. According to established electrodiagnostic criteria demyelinating form of GBS was most common (68%) compared to axonal (18,7%) or mixed form (12,5%). No children had antecendent Campylobacter jejuni infection. Antiganglioside antibodies were detected in 18,7% of patients associated with demyelinating or mixed (axonal/demyelinating) form. Time to nadir and recovery period of walking ability is prolonged more often in demyelinating GBS. Clinical improvement occur earlier compared to improvement of abnormal electrophysiological parameters.Outcome was excellent in 11 in the period 1 month-8.5 years. Hyperreflexia usually appeared in recovery period suggesting involvement of upper motor neurons or spinal interneurons occurring in Croatian children with both demyelinating and axonal form of GBS usually associated with milder course of disease.

The role of apolipoprotein E in Guillain-Barré syndrome and experimental autoimmune neuritis

Apolipoprotein E (apoE) is a 34.2 kDa glycosylated protein characterized by its wide tissue distribution and multiple functions. ApoE has been widely studied in lipid metabolism, cardiocerebrovascular diseases, and neurodegenerative diseases like Alzheimer's disease and mild cognitive impairment, and so forth. Recently, a growing body of evidence has pointed to nonlipid related properties of apoE, including suppression of T cell proliferation, regulation of macrophage function, facilitation of lipid antigen presentation by CD1 molecules to natural killer T (NKT) cells, and modulation of inflammation and oxidation. By these properties, apoE impacts physiology and pathophysiology at multiple levels. The present paper summarizes updated studies on the immunoregulatory function of apoE, with special focus on isoform-specific effects of apoE on Guillain-Barré syndrome (GBS) and its animal model experimental autoimmune neuritis (EAN).

Alemtuzumab in the treatment of IVIG-dependent chronic inflammatory demyelinating polyneuropathy

Chronic inflammatory demyelinating polyneuropathy (CIDP) is an idiopathic immune mediated neuropathy causing demyelination and conduction block thought to occur as the result of an aberrant autoimmune response resulting in peripheral nerve inflammation mediated by T cells and humoral factors. Diagnosis commonly prompts initial treatment with steroids or intravenous immunoglobulin (IVIG) on which 5-35% subsequently become dependent to maintain function. Despite a number of small scale trials, the role for alternative long-term immunosuppression remains unclear. Alemtuzumab is a humanised monoclonal antibody targeting the CD52 antigen present on the surface of lymphocytes and monocytes. A single intravenous infusion results in rapid and profound lymphopoenia lasting >12 months. We report its use and clinical outcome in a small series of patients with severe IVIG-dependent CIDP. Seven patients (4 Males; 3 Females) who had failed to respond to conventional immunosuppression were treated in 5 centres receiving 9 courses of alemtuzumab (dose range 60-150 mg). Following treatment, mean monthly IVIG use fell 26% from 202 to 149 g and IVIG administration frequency from 22 to 136 days. Two patients had prolonged remission, two patients had a partial response and no clear benefit was observed in the remaining three patients (2 Males, 1 Females). Responding patients had a younger age at onset (19.5 years) and shorter disease duration than non-responders. Three patients developed autoimmune disease following treatment. Alemtuzumab may offer an alternative treatment for a subset of early onset IVIG dependent CIDP patients failing conventional immunosuppressive agents, but concerns about toxicity may limit its use.

Expression of RhoA by inflammatory macrophages and T cells in rat experimental autoimmune neuritis

RhoA is one of the best-studied members of Rho GTPases. Experimental autoimmune neuritis (EAN), which is characterized by infiltration of T cells and macrophages into the peripheral nervous system, is an autoantigen-specific T-cell-mediated animal model of human Guillain-Barré Syndrome. In this study, RhoA expression has been investigated in the dorsal/ventral roots of EAN rats by immunohistochemistry. A significant accumulation of RhoA+ cells was observed on Day 12, with a maximum around Day 15, correlating to the clinical severity of EAN. In dorsal/ventral roots of EAN, RhoA+ cells were seen in perivascular areas but also in the parenchyma. Furthermore, double-labelling experiments showed that the major cellular sources of RhoA were reactive macrophages and T cells. In conclusion, this is the first demonstration of the presence of RhoA in the dorsal/ventral roots of EAN. The time courses and cellular sources of RhoA together with the functions of RhoA indicate that RhoA may function to facilitate macrophage and T-cell infiltration in EAN and therefore could be a potential therapeutic target.

Chronic inflammatory demyelinating polyneuropathy: A 6-year retrospective clinical study of a hospital-based population

We reviewed the clinical, electrophysiological, laboratory and neuroimaging features of 25 patients with chronic inflammatory demyelinating polyneuropathy (CIDP) admitted to Aeginition Hospital from 1996 to 2001. We also investigated the response to several treatment modalities. The aim was to reveal the clinical spectrum of the disease; the diagnostic criteria developed by the Ad Hoc Subcommittee of the American Academy of Neurology (AAN) in 1991 were used. The subjects consisted of 17 men (68%) and eight women (32%) aged 18-81 years (mean age: 48.5 years) with CIDP. Eighteen patients (72%) had a symmetric neuropathy, whereas seven (28%) had an asymmetric neuropathy. Two patients (8%) had a pure sensory neuropathy. Nine (36%) presented with cranial nerve involvement and only one (4%) had central nervous system demyelination. Most patients had a satisfactory response after treatment with corticosteroids, intravenous immunoglobulins, plasma exchange and azathioprine. In conclusion, CIDP is a clinically heterogeneous disorder. It is one of the few serious chronic neuropathies that has a good (although not permanent) treatment response.

Mechanisms of immune regulation in the peripheral nervous system

The peripheral nervous system (PNS) is a target for heterogenous immune attacks mediated by different components of the systemic immune compartment. T cells, B cells, and macrophages can interact with endogenous, partially immune-competent glial cells and contribute to local inflammation. Cellular and humoral immune functions of Schwann cells have been well characterized in vitro. In addition, the interaction of the humoral and cellular immune system with the cellular and extracellular components in the PNS may determine the extent of tissue inflammation and repair processes such as remyelination and neuronal outgrowth. The animal model experimental autoimmune neuritis (EAN) allows direct monitoring of these immune responses in vivo. In EAN contributions to regulate autoimmunity in the PNS are made by adhesion molecules and by cytokines that orchestrate cellular interactions. The PNS has a significant potential to eliminate T cell inflammation via apoptosis, which is almost lacking in other tissues such as muscle and skin. In vitro experiments suggest different scenarios how specific cellular and humoral elements in the PNS may sensitize autoreactive T cells for apoptosis in vivo. Interestingly several conventional and novel immunotherapeutic approaches like glucocorticosteroids and high-dose antigen therapy induce T cell apoptosis in situ in EAN. A better understanding of immune regulation and its failure in the PNS may help to develop improved, more specific immunotherapies.

Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP): A Review of Clinical Syndromes and Treatment Approaches in Clinical Practice

Chronic inflammatory demyelinating polyneuropathy (CIDP) is a chronic, acquired immune and inflammatory disorder of the peripheral nervous system. The classic form of the disorder is manifested by progressive or relapsing proximal or generalized limb weakness and areflexia, and usually easily recognized; it is the large number of regional and functional variants and variety of associated illnesses that pose a challenge to the clinician in practice. Similarly, laboratory and electromyography criteria have been developed to confirm the diagnosis; however, these various schemes are contrived because only 50% to 60% of patients with typical clinical features of CIDP fulfill these strict electrodiagnostic research criteria. Several studies have established the efficacy of immune therapies such as corticosteroids, plasma exchange, and intravenous immune globulin as the mainstay of treatment of CIDP, but these treatments might provide only short-term benefit. This review offers an approach to the evaluation and management of patients with CIDP and highlights the difficult clinical problems in those who do not respond or frequently relapse after treatment with standard therapies such as patients with CIDP and concomitant axonal loss, and the assessment of those with CIDP and concurrent diseases such as diabetes mellitus.

Localization of major gangliosides in the PNS: implications for immune neuropathies

Antibodies targeting major gangliosides that are broadly distributed in the nervous system are sometimes associated with clinical symptoms that imply selective nerve damage. For example, anti-GD1a antibodies are associated with acute motor axonal neuropathy (AMAN), a form of Guillain-Barré syndrome that selectively affects motor nerves, despite reports that GD1a is present in human axons and myelin and is not expressed differentially in motor versus sensory roots. We used a series of high-affinity monoclonal antibodies (mAbs) against the major nervous system gangliosides GM1, GD1a, GD1b and GT1b to test whether any of them bind motor or sensory fibres differentially in rodent and human peripheral nerves. The following observations were made. (i) Some of the anti-GD1a antibodies preferentially stained motor fibres, supporting the association of human anti-GD1a antibodies with predominant motor neuropathies such as AMAN. (ii) A GD1b antibody preferentially stained the large dorsal root ganglion (DRG) neurones, in keeping with the proposed role of human anti-GD1b antibodies in sensory ataxic neuropathies. (iii) Two mAbs with broad structural cross-reactivity bound to both gangliosides and peripheral nerve proteins. (iv) Myelin was poorly stained; all clones stained axons nearly exclusively. Our findings suggest that anti-ganglioside antibody fine specificity as well as differences in ganglioside accessibility in axons and myelin influence the selectivity of injury to different fibre systems and cell types in human autoimmune neuropathies.

Interferon-gamma, tumor necrosis factor-alpha, and transforming growth factor-beta inhibit cyclic AMP-induced Schwann cell differentiation

Schwann cells differentiate in vivo in response to contact with axons, and cAMP simulates some of these aspects of differentiation in vitro, particularly morphologic changes and expression of certain phenotypic molecules. Unfractionated inflammatory cytokines inhibit cAMP-induced Schwann cell expression of galactolipids (Gal). We sought to identify which cytokines were responsible for this inhibition and to determine whether other phenotypic indicators of Schwann cell differentiation were also affected. Neonatal rat Schwann cells were incubated in vitro with 1 mM 8 Bromo cAMP (8 Br cAMP) with or without the addition of interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-2, IL-6, tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), or transforming growth factor-beta (TGF-beta). Cells were then examined for morphologic changes and for expression of surface Gal and low-affinity nerve growth factor receptor (NGFRp75), employing indirect immunofluorescence. 8 Br cAMP induced Schwann cell upregulation of Gal, downregulation of NGFRp75, and the cells became enlarged and somewhat amorphous and irregular in appearance. Cells treated with IFN-gamma or TNF-alpha alone were more bipolar and more evenly distributed on coverslips than were control cells, whereas TGF-beta alone induced elongated cells often in a swirling pattern. None of the cytokines alone induced upregulation of Gal or downregulation of NGFRp75. TNF-alpha, IFN-gamma, and TGF-beta inhibited the 8 Br cAMP-induced morphologic changes, as well as the upregulation of Gal and downregulation of NGFRp75. The other cytokines had no effects on Gal or NGFRp75 expression. Thus, these three cytokines, which are present in inflammatory lesions in the peripheral nervous system, are capable of inhibiting Schwann cell differentiation.

Vaccination, prevention, and treatment of experimental autoimmune neuritis (EAN) by an oligomerized T cell epitope

Using a polypeptide oligomer harboring 16 repeats of the neuritogenic epitope (aa 58-73) of myelin P2 protein separated by spacers, enhancement of the immune response to the P2 protein, an important neuritogenic autoantigen in experimental autoimmune neuritis (EAN), was attempted. In contrast to a previous study with PLP-16-mer antigen-specific response of T cells was attenuated at all doses examined to a variable degree. Treatment of Lewis rats with the P2-16-mer up to 2 months before immunization with P2(53-78) (vaccination) or after immunization but before appearance of disease (prevention) had a strong tolerizing effect against the induction of EAN on immunization with P2(53-78). Moreover, rats injected with 200 microg of the P2-16-mer i.v. on day 11 after disease induction, at which time the initial signs of disease had appeared, were almost completely protected against progression of clinical disease, whereas animals treated with the same amount of monomeric control peptide developed severe disease (treatment). Similar results were obtained by i.v. treatment of adoptive-transfer EAN with the P2-16-mer. The lack of clinical signs of disease after 16-mer therapy could be correlated with a reduced proliferative response of P2(53-78)-specific lymph node cells. The frequency of apoptotic T cells in sciatic nerve or in lymph node cells, however, was not increased by the 16-mer treatment, suggesting that induction of anergy or other forms of peripheral tolerance may be responsible for the effect. Thus, the oligomerized P2 peptide antigen was highly effective in all three treatment modalities examined in this specific autoreactive T cell-mediated immune response.

The role of matrix metalloproteinases in autoimmune damage to the central and peripheral nervous system

Members of the family of matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of inflammatory demyelination. MMPs apparently mediate important steps in the genesis of inflammatory demyelination, such as cell migration, blood-brain/nerve barrier breakdown, demyelination, and cytokine activation. This review will highlight in vitro as well as in vivo findings, which support the importance of this group of proteases in the pathogenesis of inflammatory demyelinating disorders of the central and peripheral nervous system.

High-affinity anti-ganglioside IgG antibodies raised in complex ganglioside knockout mice: reexamination of GD1a immunolocalization

Gangliosides, sialic acid-bearing glycosphingolipids, are highly enriched in the vertebrate nervous system. Anti-ganglioside antibodies are associated with various human neuropathies, although the pathogenicity of these antibodies remains unproven. Testing the pathogenic role of anti-ganglioside antibodies will be facilitated by developing high-affinity IgG-class complement-fixing monoclonal anti-bodies against major brain gangliosides, a goal that has been difficult to achieve. In this study, mice lacking complex gangliosides were used as immune-naive hosts to raise anti-ganglioside antibodies. Wild-type mice and knockout mice with a disrupted gene for GM2/GD2 synthase (UDP-N-acetyl-D-galactosamine : GM3/GD3 N-acetyl-D-glactosaminyltransferase) were immunized with GD1a conjugated to keyhole limpet hemocyanin. The knockout mice produced a vigorous anti-GD1a IgG response, whereas wildtype littermates failed to do so. Fusion of spleen cells from an immunized knockout mouse with myeloma cells yielded numerous IgG anti-GD1a antibody-producing colonies. Ganglioside binding studies revealed two specificity classes; one colony representing each class was cloned and characterized. High-affinity monoclonal antibody was produced by each hybridoma : an IgG1 that bound nearly exclusively to GD1a and an IgG2b that bound GD1a, GT1b, and GT1aalpha. Both antibodies readily readily detected gangliosides via ELISA, TLC immune overlay, immunohistochemistry, and immunocytochemistry. In contrast to prior reports using anti-GD1a and anti-GT1b IgM class monoclonal antibodies, the new antibodies bound avidly to granule neurons in brain tissue sections and cell cultures. Mice lacking complex gangliosides are improved hosts for raising high-affinity, high-titer anti-ganglioside IgG antibodies for probing for the distribution and physiology of gangliosides and the pathophysiology of anti-ganglioside antibodies.

Monoclonal antibodies raised against Guillain-Barré syndrome-associated Campylobacter jejuni lipopolysaccharides react with neuronal gangliosides and paralyze muscle-nerve preparations

Guillain-Barré syndrome and its variant, Miller-Fisher syndrome, are acute, postinfectious, autoimmune neuropathies that frequently follow Campylobacter jejuni enteritis. The pathogenesis is believed to involve molecular mimicry between sialylated epitopes on C. jejuni LPSs and neural gangliosides. More than 90% of Miller-Fisher syndrome cases have serum anti-GQ1b and anti-GT1a ganglioside antibodies that may also react with other disialylated gangliosides including GD3 and GD1b. Structural studies on LPS from neuropathy-associated C. jejuni strains have revealed GT1a-like and GD3-like core oligosaccharides. To determine whether this structural mimicry results in pathogenic autoantibodies, we immunized mice with GT1a/GD3-like C. jejuni LPS and then cloned mAb's that reacted with both the immunizing LPS and GQ1b/GT1a/GD3 gangliosides. Immunohistology demonstrated antibody binding to ganglioside-rich sites including motor nerve terminals. In ex vivo electrophysiological studies of nerve terminal function, application of antibodies either ex vivo or in vivo via passive immunization induced massive quantal release of acetylcholine, followed by neurotransmission block. This effect was complement-dependent and associated with extensive deposits of IgM and C3c at nerve terminals. These data provide strong support for the molecular mimicry hypothesis as a mechanism for the induction of cross-reactive pathogenic anti-ganglioside/LPS antibodies in postinfectious neuropathies.

Monoclonal antibodies raised against Guillain-Barré syndrome-associated Campylobacter jejuni lipopolysaccharides react with neuronal gangliosides and paralyze muscle-nerve preparations

Guillain-Barré syndrome and its variant, Miller-Fisher syndrome, are acute, postinfectious, autoimmune neuropathies that frequently follow Campylobacter jejuni enteritis. The pathogenesis is believed to involve molecular mimicry between sialylated epitopes on C. jejuni LPSs and neural gangliosides. More than 90% of Miller-Fisher syndrome cases have serum anti-GQ1b and anti-GT1a ganglioside antibodies that may also react with other disialylated gangliosides including GD3 and GD1b. Structural studies on LPS from neuropathy-associated C. jejuni strains have revealed GT1a-like and GD3-like core oligosaccharides. To determine whether this structural mimicry results in pathogenic autoantibodies, we immunized mice with GT1a/GD3-like C. jejuni LPS and then cloned mAb's that reacted with both the immunizing LPS and GQ1b/GT1a/GD3 gangliosides. Immunohistology demonstrated antibody binding to ganglioside-rich sites including motor nerve terminals. In ex vivo electrophysiological studies of nerve terminal function, application of antibodies either ex vivo or in vivo via passive immunization induced massive quantal release of acetylcholine, followed by neurotransmission block. This effect was complement-dependent and associated with extensive deposits of IgM and C3c at nerve terminals. These data provide strong support for the molecular mimicry hypothesis as a mechanism for the induction of cross-reactive pathogenic anti-ganglioside/LPS antibodies in postinfectious neuropathies.

Induction of experimental autoimmune neuritis in CD4-8-C57BL/6J mice

The C57BL/6J mice strain is known to be reputedly resistant to induction of experimental autoimmune neuritis (EAN), an animal model of Guillain-Barré syndrome in humans. Here we describe the induction of EAN in mice of the C57BL/6J background by transfer into naive syngeneic recipients bovine peripheral nerve myelin (BPM)-primed donor lymph node cells that had been stimulated in vitro with the bovine peripheral nervous system (PNS) myelin P2 protein peptide 57-81 followed by challenge with BPM, Freund's complete adjuvant and pertussis toxin. EAN was more severe, both clinically and histologically, and accompanied by extensive infiltration of inflammatory cells and demyelination in peripheral nerves when examined on day 30 after transfer of primed T cells from CD4- 8- mice into identical naive hosts than after transfer of cells from primed wild type, CD4-/- or CD8-/- mice to corresponding recipient animals. EAN in CD4-8- mice was also associated with elevated numbers of P2 peptide-reactive interferon-y (TFN-gamma) secreting cells and alphabeta T cells were present in lymph nodes and spleens. The data suggest that PNS myelin activated T cells from an EAN-resistant mice strain are capable of homing to the PNS. The expanded CD4-8- alphabeta T cells may have helper and effector functions, related to initiation of EAN in the CD4-8- mice. Lack of CD4+ and CD8+ expressing cells does not prevent the initiation of an autoimmune disease.

Resistance and susceptibility to experimental autoimmune neuritis in Sprague-Dawley and Lewis rats correlate with different levels of autoreactive T and B cell responses to myelin antigens

Experimental autoimmune neuritis (EAN) is a CD4+ T cell-mediated, inflammatory demyelinating disease of the peripheral nervous system (PNS) that serves as a model for Guillain-Barré syndrome (GBS) in humans. Various mouse and rat strains show different susceptibilities to EAN that can be induced by immunization with bovine PNS myelin (BPM) + Freund's complete adjuvant (FCA). We examined PNS-induced T and B cell responses and cytokine protein production as well as mRNA expression to study the mechanisms behind susceptibility to EAN in Lewis rats and resistance in Sprague-Dawley (SD) rats. Lewis rats with EAN have elevated PNS myelin-reactive interferon-gamma (IFN-gamma) production, TNF-alpha mRNA expression, and increased B cell responses to PNS myelin antigens, but low PNS myelin-reactive transforming growth factor-beta (TGF-beta) and interleukin (IL)-10 mRNA expression in lymph node mononuclear cells (MNC). In contrast, resistance to EAN in SD rats is associated with reduced BPM and P2 peptide-reactive IFN-gamma production, TNF-alpha mRNA expression, and suppressed B cell responses to PNS myelin antigens as well as up-regulation of TGF-beta and IL-10 mRNA expression. Resistance to EAN is also associated with low-grade inflammation or absence of histological evidence of EAN. These results suggest that differential autoreactive T and B cells responses to PNS myelin antigens are strain specific, and the susceptibility to EAN is related to quantitative rather than qualitative differences in distribution between proinflammatory and anti-inflammatory cytokines.

Electrophysiological classification of Guillain-Barré syndrome: clinical associations and outcome. Plasma Exchange/Sandoglobulin Guillain-Barré Syndrome Trial Group

We performed electrophysiological and serological testing within 15 days of symptom onset on 369 patients with Guillain-Barré Syndrome (GBS) enrolled in a trial comparing plasma exchange, intravenous immunoglobulin, and both treatments. Patients were classified into five groups by motor nerve conduction criteria; 69% were demyelinating, 3% axonal, 3% inexcitable, 2% normal, and 23% equivocal. Six of 10 (60%) patients with axonal neurophysiology had had a preceding diarrheal illness compared with 71 of 359 (20%) in other groups. Antiganglioside GM1 antibodies were present in a higher proportion of patients with axonal physiology or inexcitable nerves than other patients. The number dead or unable to walk unaided at 48 weeks was greater in the group with initially inexcitable nerves (6 of 12, 50%) compared with the rest (52 of 357, 15%), but was not significantly different between the axonal (1 of 10, 10%) and demyelinating (44 of 254, 17%) groups. Sensory action potentials and clinical sensory examination were both normal in 53 of 342 (16%) patients, and these "pure motor GBS" patients were more likely than other GBS patients to have IgG antiganglioside GM1 antibodies and to have had preceding diarrhea but had a similar outcome. The axonal group was more likely than other groups to have normal sensory action potentials. The outcomes in response to the three treatments did not differ in any subgroup (including patients with pure motor GBS or preceding diarrhea) or any neurophysiological category.

Thalidomide prolongs experimental autoimmune neuritis in Lewis rats

Thalidomide is reported to have immunomodulatory and anti-inflammatory effects, which have led to its use in the treatment of a number of immune-mediated disorders, including leprosy, discoid lupus and Behcet's disease, and to prevent immunological rejection phenomena following skin and bone marrow grafts. Experimental autoimmune neuritis (EAN) is a CD4+ T-cell-mediated demyelinating autoimmune disease, which represents an animal model for the study of the immunopathogenesis and immunotherapy of Guillain-Barré syndrome (GBS) in humans. We examined the effect of thalidomide in Lewis rats with EAN, which was induced by immunization with bovine peripheral nerve myelin (BPM) and complete Freund's adjuvant (CFA). Thalidomide prolonged clinical EAN when given at a dose of 200 mg/kg/day by gavage. This clinical effect was associated with increased numbers of inflammatory cells in sciatic nerve sections and elevated numbers of interferon-gamma (IFN-gamma) mRNA-expressing cells among lymph node mononuclear cells from thalidomide-treated EAN rats on day 17 postimmunization, i.e. at the peak of clinical EAN. The finding that thalidomide prolongs clinical EAN is in agreement with the clinical polyneuropathy reported in patients receiving treatment with thalidomide and limits its clinical usefulness.

Demyelinating inflammatory neuropathies, including Guillain-Barré syndrome

The highly complex and multiple mechanisms responsible for the development of demyelinating neuropathies are reviewed, in particular Guillain-Barré syndrome and its variant Miller Fisher syndrome, chronic inflammatory demyelinating neuropathy, multifocal motor neuropathy, anti-myelin-associated glycoprotein neuropathy, as well as experimental models. Recent investigations into the role of auto antibodies against myelin proteins, or glycolipids have given insights into the pathogenesis of demyelinating inflammatory neuropathies.

Antiglycolipid antibodies in motor neuropathies

In peripheral neuropathies with monoclonal gammopathy, mainly IgM, it appears clear from clinical, electrophysiological, and experimental data, that the target glycolipid or glycolipid epitope for the IgM is related to the type of neuropathy--purely sensory, predominantly sensory, or uniquely motor. Investigations have focused on chronic peripheral neuropathies associated with polyclonal IgM reactivity to glycolipids. Although IgM anti-GM1 antibodies are present in normal controls, there is a subgroup of motor neuropathies with high titer anti-GM1 antibodies, mainly multifocal neuropathies with conduction blocks (MMNCB). Another subgroup of MMNCB may include IgM anti-SGPG antibodies that do not cross-react with MAG. The importance of the fine structure of the epitope has to be considered in view of the pathogenicity of the antibody. It may bear consequences on its binding properties on the neuronal surfaces and on its biological implications.

Cytokine production and the pathogenesis of experimental autoimmune neuritis and Guillain-Barré syndrome

Acute inflammatory demyelinating polyradiculoneuropathy (Guillain-Barré syndrome, GBS) and its animal model experimental autoimmune neuritis (EAN) are prototypes of T cell-mediated autoimmune diseases affecting the peripheral nervous system (PNS). Perivascular accumulation of macrophages and T lymphocytes in the PNS, and high levels systemically of PNS myelin antigen-reactive T cells are characteristic features of both diseases, thereby suggesting a pathogenic role for immunoregulatory cytokines. Here we summarise recent studies that have clearly documented that Th1/Th2/Th3 cytokines are differently upregulated during various clinical phases of EAN and GBS. The observations indicate that the role of cytokines in immune regulation and autoimmune disease is more complex than a simple Th1-Th2 dichotomy would suggest. New treatments may be searched for that counteract this complex cytokine imbalance. Treatments with antibodies that selectively target certain pro-inflammatory cytokines, as well as with immunomodulatory preparations that promote cytokines that beneficially influence the disease course should be in focus of future therapeutic trials.

Cytokine dichotomy in peripheral nervous system influences the outcome of experimental allergic neuritis: dynamics of mRNA expression for IL-1 beta, IL-6, IL-10, IL-12, TNF-alpha, TNF-beta, and cytolysin

Experimental autoimmune neuritis (EAN) is a T-cell-mediated autoimmune disease of the peripheral nervous system (PNS) that can be actively induced in Lewis rats by immunization with bovine PNS myelin and Freund's complete adjuvant. EAN is used as an animal model of the Guillain-Barré syndrome (GBS) in humans. To study the potential role of cytokines in EAN, we used in situ hybridization to detect mRNA expression of interleukin 1 beta (IL-1 beta), IL-6, IL-10, IL-12, tumor necrosis factor-alpha (TNF-alpha), TNF-beta, and cytolysin in sciatic nerve sections over the course of EAN. Cells expressing IL-1 beta and IL-6 mRNA appeared early and peaked on Day 7 postimmunization (p.i.), i.e., at onset of clinical signs of EAN, consistent with a role of these cytokine in an early immune response leading to autoaggressive immunity in EAN. TNF-alpha, TNF-beta, and IL-12 mRNA expression was maximally upmodulated on Day 14 p.i., i.e., at height of clinical EAN, favoring a role for these cytokines in disease development. On the contrary, transcription of cytolysin and IL-10 in sciatic nerves reached maxima during clinical improvement of EAN. The data argue for a major proinflammatory role for IL-1 beta, IL-6, TNF-alpha, TNF-beta, and IL-12 and a disease downregulating function for both cytolysin and IL-10 at the target site in EAN. These findings have relevance for future studies on pathogenesis and treatment of GBS in humans.