Effects on axonal conduction of anti-ganglioside sera and sera from patients with Guillain-Barré syndrome

Th17 helper cell and T-cell immunoglobulin and mucin domain 3 involvement in Guillain-Barré syndrome

OBJECTIVE AND DESIGN

We investigated the involvement of Th17 cells and T-cell immunoglobulin and mucin domain 3 (TIM-3) in Guillain-Barré syndrome (GBS) in comparison to healthy subjects.

MATERIALS AND SUBJECTS

Peripheral blood samples were obtained from 29 healthy subjects and 29 GBS patients.

TREATMENT

Peripheral blood mononuclear cells (PBMCs) and CD4(+) T cells were stimulated with anti-CD3 and anti-CD28 mAbs, in the absence or presence of anti-TIM-3 mAb.

METHODS

mRNA levels of TIM-3 and the transcription factor retinoic acid-related orphan receptor γt (RORγt) were determined by RT-PCR and were expressed relative to β-actin mRNA (housekeeping gene). Serum IFN-γ and IL-17 levels were determined by ELISA.

RESULTS

Compared to controls, relative TIM-3 mRNA levels were lower in both stimulated and unstimulated PBMCs from GBS patients. Unstimulated GBS CD4(+) T cells and GBS CD4+ T cells stimulated with anti-CD3 and CD28 mAbs had higher relative RORγt mRNA expression compared to controls. GBS CD4(+) T cells secreted significantly more IFN-γ and IL-17 in the presence of anti-TIM-3 mAb. GBS patients had (1) higher numbers of Th17, but not Th1 or Th2 cells in peripheral blood and (2) higher serum concentrations of IFN-γ and IL-17 compared to controls.

CONCLUSION

TIM-3 may inhibit Th17 cell activation, thereby modulating their cytokine secretion patterns. Th17 cell differentiation, IL-17 levels, and TIM-3 regulation may be involved in the pathogenesis of GBS.

Campylobacter jejuni DNA-binding protein from starved cells in Guillain-Barré syndrome patients

Campylobacter jejuni enteritis is frequently associated with an axonal form of Guillain-Barré syndrome (GBS) and C. jejuni DNA-binding protein from starved cells (C-Dps) induces paranodal myelin detachment and axonal degeneration through binding with sulfatide in vivo. Here we investigated the invasion of C-Dps into hosts with C. jejuni-related GBS. Our analyses of patient sera found that both C-Dps and anti-C-Dps antibodies were most commonly detected in sera from C. jejuni-related GBS patients (5/27, 14.8% and 15/24, 62.5%; respectively). These findings suggest that C-Dps invades the host and may potentially contribute to the peripheral nerve damage in C. jejuni-related GBS.

[Antiganglioside antibodies--their pathophysiological effects on Guillain-Barré syndrome and variants]

Gangliosides, N-acetylneuraminic acid (sialic acid)-bearing glycosphingolipids, are believed to reside in clusters within membrane microdomains, called lipid rafts or glycosynapse. Recent studies demonstrated that antiganglioside antibodies play an important role in the pathogenesis of Guillain-Barré syndrome (GBS) and Fisher syndrome (FS). The anti-GM1 antibodies are likely to damage peripheral nerves through complement activation with dysfunction of voltage-gated sodium channels. Some antiganglioside antibodies may cause dysfunction of voltage-gated calcium channels without complement activation. Clustered epitopes of ganglioside complexes (GSCs) consisting of two gangliosides can be targeted by serum antibodies in GBS and FS. Anti-GD1a/GD1b complex antibodies are associated with severe GBS. Approximately 50% of FS patients have antibodies to GSCs containing GQ1b or GT1a. Various glycolipids including GSCs may form complex glycolipid environment in the cell membrane, regulating the accessibility and the avidity of antiganglioside antibodies. In addition to antibody specificity, the glycolipid environment or specific distribution of target gangliosides in peripheral nervous system can influence pathogenic effects of antiganglioside antibodies in GBS and FS. Conformational and functional analyses of glycoepitopes of GSCs in the biological membrane will provide new vistas to research on antibody-antigen interaction in GBS, and shed light on microdomain function mediated by carbohydrate-to-carbohydrate interaction.

Antibodies to gangliosides and ganglioside complexes in Guillain-Barré syndrome and Fisher syndrome: mini-review

Antiganglioside antibodies play a pathogenic role in the pathophysiology of Guillain-Barré syndrome (GBS) and Fisher syndrome (FS). Antiganglioside antibody-mediated nerve injury is likely to result from nerve damage through complement activation or dysfunction of molecules such as voltage-gated sodium and calcium channels. Clustered epitopes of complexes of two gangliosides in the cell membrane can be targeted by serum antibodies in GBS and FS and may regulate the accessibility and avidity of antiganglioside antibodies. The glycolipid environment or the specific distribution of target gangliosides in the peripheral nervous system may also influence the pathogenic effect of antiganglioside antibodies in GBS and FS. Structural and functional analyses of glycoepitopes of ganglioside complexes in membranes will provide new vistas on antibody-antigen interaction in GBS and shed light on microdomain function mediated by carbohydrate-carbohydrate interactions, which may lead to novel treatments for GBS and FS.

[The significance of intravenous immunoglobulin in treatment of immune-mediated polyneuropathies]

Long-term treatment of immune-mediated polyneuropathies remains difficult. For acute polyneuritis, or Guillain-Barré syndrome, the established standard therapy utilizes high doses of polyvalent intravenous immunoglobulins (IVIG). A recently published randomized placebo-controlled study of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) showed IVIG to be clinically effective also for this disorder in both short and long term. This survey presents data of this so-called ICE study ("Intravenous immune globulin for the treatment of chronic inflammatory demyelinating polyradiculoneuropathy"). It also discusses the value of IVIG in the treatment of immune-mediated polyneuropathies.

Effect of anti-GM2 antibodies on rat sciatic nerve: electrophysiological and morphological study

We found that a monoclonal human IgM anti-GM2 was fixed in rat sciatic axons and Schwann cells and was able to activate human complement. The passive transfer of IgM and complement in sciatic nerves can induce an acute alteration in nerve conduction. When the transfer of IgM plus complement was repeated for 10 days, the compound action motor potential amplitude was very low and the morphological study showed axons and myelin damage. Without human complement, IgM can only slightly disorganize the myelin by separating some layers, probably by interfering with the functional role of gangliosides in the myelin package.

Intravenous immunoglobulins in the treatment of immune neuropathies

PURPOSE OF REVIEW

The aim of this review is to describe the value of high-dose polyclonal intravenous immunoglobulins as a treatment option in autoimmune disorders affecting the peripheral nervous system.

RECENT FINDINGS

A randomized placebo-controlled trial in patients with chronic inflammatory demyelinating polyradiculoneuropathy revealed short-term and long-term efficacy and safety of intravenous immunoglobulins as a treatment option for the chronically inflamed peripheral nervous system. Case reports suggest that the subcutaneous administration of immunoglobulins may represent a convenient alternative.

SUMMARY

Intravenous immunoglobulin represents an effective and safe treatment option in patients with autoimmune-mediated diseases affecting the peripheral nerves.

From bench to bedside--experimental rationale for immune-specific therapies in the inflamed peripheral nerve

Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy are autoimmune-mediated inflammatory diseases of the PNS. In recent years, substantial progress has been made towards understanding the immune mechanisms that underlie these conditions, in large part through the study of experimental models. Here, we review the available animal models that partially mimic human Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy, and discuss the wide range of therapeutic approaches that have been successfully established in these models of inflammatory neuropathies. Transfer of this preclinical knowledge to patients has been far less successful, and inflammatory neuropathies are still associated with significant morbidity and mortality. We will summarize successful therapeutic trials in human autoimmune neuropathies to provide a vantage point for the transfer of experimental treatment strategies to clinical practice in immune-mediated diseases of the peripheral nerve.

Immune circuitry in the peripheral nervous system

PURPOSE OF REVIEW

The aim of this review is to describe the local immune circuitry in the peripheral nervous system and its dialogue with systemic immunity under pathological conditions. Specifically, interactions of the immune system with cellular and extracellular components within peripheral nerve and immune functions of tissue-resident endoneurial macrophages and Schwann cells will be discussed.

RECENT FINDINGS

New insights into the elements involved in the pathogenesis of immune-mediated disorders of the peripheral nervous system provide a better understanding of the complex interplay of these cellular and molecular components in the immunology of the peripheral nervous system.

SUMMARY

The application of innovative and cutting-edge technologies to the study of immunoinflammatory disorders of the peripheral nervous system provides a better understanding of underlying principles of the organization of the immune network present in the peripheral nerve and its dialogue with the systemic immune system. This may foster the development of specific and highly effective therapies for immune-mediated disorders of the peripheral nerve.

Biological roles of anti-GM1 antibodies in patients with Guillain-Barré syndrome for nerve growth factor signaling

To reveal the biological and pathological roles of anti-GM1 antibody in Guillain-Barré syndrome (GBS), we examined its effects on nerve growth factor (NGF) induced TrkA autophosphorylation (NGF-TrkA signaling) in PC12 cells, a sympathetic nerve cell line. The NGF-TrkA signaling is enhanced by exogenous GM1 ganglioside and this phenomenon is regarded as one of the functional aspects of GM1. The IgGs purified from patients' sera inhibited the NGF-TrkA signaling in GM1 pre-incubated PC12 cells. The degrees of inhibition by IgGs from patients paralleled their immunological reactivity to GM1. In addition, the IgGs also inhibited the neurite outgrowth of NGF-treated PC12 cells. Immunoglobulins in the rabbit sera, which were immunized by GM1, also caused a similar suppressive phenomenon. These results suggested that the anti-GM1 antibody could play roles in pathophysiology in anti-GM1 antibody positive GBS through interfering with the neurotrophic action of NGF and GM1 mediated signal modulation including NGF-TrkA signaling. It is suggested that the modulation of GM1 function is one important action of antibodies and could be one of the important mechanisms in GBS.

Ca2+ Channel Currents Inhibited by Serum from Select Patients with Guillain-Barré Syndrome

We performed an electrophysiological study demonstrating inhibition of spontaneous muscle action potentials within a coculture of rat muscle and spinal cord by exposure to serum, as well as purified IgG, from patients with the acute motor axonal neuropathy (AMAN) variant of Guillain-Barré syndrome (GBS). However, exposure to serum from two patients with the acute inflammatory demyelinating polyneuropathy (AIDP) form of GBS had no effect. Using a whole-cell recording technique, we then investigated the effects of serum and purified IgG from patients with GBS on voltage-dependent calcium channel (VDCC) currents in nerve growth factor-differentiated PC12 cells. Serum from patients with GBS (AMAN) inhibited VDCC currents in PC12 cells, which was fully reversible by washing with the bath solution. Similarly, purified IgG from the serum of two patients with GBS (AMAN) also inhibited VDCC currents in PC12 cells. In contrast, sera from patients with AIDP and healthy volunteers did not affect VDCC currents in PC12 cells. These results suggest that muscle weakness in some patients with GBS might be induced by inhibition of Ca2+ channel currents within motor nerve terminals.

Antiglycolipid antibodies in Guillain-Barré syndrome and related diseases: Review of clinical features and antibody specificities

Guillain-Barré syndrome (GBS) is an acute inflammatory polyradiculoneuropathy that usually develops following a respiratory or intestinal infection. Although the pathogenic mechanisms of GBS have not been fully established, both humoral and cell-mediated immune factors have been shown to contribute to the disease process. Several antiglycosphingolipid (anti-GSL) antibodies have been found in the sera of patients with GBS or related diseases. Measurements of these antibody titers are very important in the diagnosis of GBS and in evaluating the effectiveness of treatments in clinical trials. The most common treatment strategies for these disorders involve plasmapheresis and the use of steroids for reducing anti-GSL antibody titers to ameliorate patients' clinical symptoms. Administration of intravenous immunoglobulin may also be beneficial in the treatment of neuropathies by suppressing the immune-mediated processes that are directed against antigenic targets in myelin and axons. In certain demyelinating neuropathies, the destruction or malfunctioning of the blood-nerve barrier, which results in the leakage of circulating antibodies into the peripheral nerve parenchyma, has been considered to be an initial step in development of the disease process. In addition, anti-GSL antibodies, such as anti-GM1, may cause nerve dysfunction and injury by interfering with the ion channel function at the nodes of Ranvier, where carbohydrate epitopes of glycoconjugates are located. These malfunctions thus contribute to the pathogenic mechanisms of certain demyelinating neuropathies.

Advances in understanding and treatment of immune-mediated disorders of the peripheral nervous system

During recent years, novel insights in basic immunology and advances in biotechnology have contributed to an increased understanding of the pathogenetic mechanisms of immune-mediated disorders of the peripheral nervous system. This increased knowledge has an impact on the management of patients with this class of disorders. Current advances are outlined and their implication for therapeutic approaches addressed. As a prototypic immune-mediated neuropathy, special emphasis is placed on the pathogenesis and treatment of the Guillain-Barré syndrome and its variants. Moreover, neuropathies of the chronic inflammatory demyelinating, multifocal motor, and nonsystemic vasculitic types are discussed. This review summarizes recent progress with currently available therapies and--on the basis of present immunopathogenetic concepts--outlines future treatment strategies.