T cell receptor V beta gene usage in Guillain-Barré syndrome

Current Therapeutic Options in Severe Guillain-Barre?? Syndrome

The classical form of Guillain-Barré syndrome (GBS) refers to an acute monophasic demyelinating motor and sensory polyneuropathy characterized by symmetric ascending flaccid weakness, along with sensory impairment and, less commonly, autonomic perturbations. Pure motor axonal forms, axonal motor, and sensory forms, as well as pure autonomic forms, have also been identified. A complex immune-mediated process leads to segmental demyelination accompanied with axonal involvement in protracted cases. Establishing strategies of immunomodulation may therefore halt and even reverse the harmful autoimmune insult to peripheral nerves. The present article reviews the current immunomodulatory options in severe GBS. A recent Cochrane meta-analysis of 6 randomized studies showed no significant improvement using corticosteroids, including either oral or intravenous methylprednisolone. Combined methylprednisolone and immunoglobulins shortened the time lapse to regain independent walking. Plasmapheresis (PE) was the first effectively proven method of immunomodulation, followed by intravenous immunoglobulins (IVIG). Both methods are comparable in their beneficial effect and were used either separately or in combination, but PE was more frequently associated with severe adverse effects requiring cessation of therapy, including a bleeding diathesis. In addition, PE is feasible only in major referral centers requiring the appropriate equipment and trained personnel. In addition, younger children may be at risk for bleeding after insertion of wide catheters. Therefore, in cases of severe GBS, IVIG is recommended as the first-line drug using a total empiric dose of 2 g/kg administered over 2 consecutive days, especially in children proven highly effective with negligible adverse effects. In protracted cases, the addition of intravenous corticosteroids to IVIG should be considered, which may shorten the duration to regain independent walking. If such therapy fails, PE should be applied using centrifugal blood separators with 5% albumin as the substitute solution.

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.

CDR3 spectratyping analysis of the T cell receptor repertoire in Guillain-Barré and Fisher syndromes

Several autoimmune and infectious disorders show oligoclonal expansion of particular T cell phenotypes. The extent of T cell involvement in the pathogenesis of Guillain-Barré syndrome (GBS), a post-infectious autoimmune neuropathy, however, is not clear. To identify the pathogenic T cell phenotypes in GBS and Fisher syndrome (FS), variations in T cell receptor use of the V beta 1-24 and V delta 1-5 chain genes were analyzed at complementarity-determining region 3 level in 119 patients with GBS or FS. Overall, V beta and V delta spectratypes were expanded more frequently in patients with GBS (V beta in 77%, V delta in 53%) or FS (V beta in 75%, V delta in 65%) than in the healthy controls (V beta in 59%, V delta in 38%). No particular spectratype was significantly associated with GBS or FS. Subgrouping the patients by Campylobacter jejuni serology and anti-ganglioside IgG antibodies also failed to detect particular spectratype gene use. The frequency of V beta 5.2 expansion tended to be higher in patients with positive Haemophilus influenzae serology (50%) than in the controls (7%), but the difference was not significant. Our findings show that oligoclonal expansion of T cells bearing particular type T cell receptor V beta and V delta genes frequently occurs in GBS and FS, suggestive that T cells mediate the development of these neuropathies. The predominant phenotypes vary, even within subgroups of patients with a syndrome of single etiological origin or those with uniform serological features.

Management of chronic inflammatory demyelinating polyradiculoneuropathy

This review briefly describes current concepts concerning the nosological status, pathogenesis and management of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). CIDP is an uncommon variable disorder of unknown but probably autoimmune aetiology. The commonest form of CIDP causes more or less symmetrical progressive or relapsing weakness affecting proximal and distal muscles. Against this background the review describes the short-term responses to corticosteroids, intravenous immunoglobulin (IVIg) and plasma exchange that have been confirmed in randomised trials. In the absence of better evidence about long-term efficacy, corticosteroids or IVIg are usually favoured because of convenience. Benefit following introduction of azathioprine, cyclophosphamide, cyclosporin, other immunosuppressive agents, and interferon-beta and -alpha has been reported but randomised trials are needed to confirm these benefits. In patients with pure motor CIDP and multifocal motor neuropathy, corticosteroids may cause worsening and IVIg is more likely to be effective. General measures to rehabilitate patients and manage symptoms, including foot drop, weak hands, fatigue and pain, are important.

Pathogenesis of Guillain-Barré syndrome

Recent neurophysiological and pathological studies have led to a reclassification of the diseases that underlie Guillain-Barré syndrome (GBS) into acute inflammatory demyelinating polyradiculoneuropathy (AIDP), acute motor and sensory axonal neuropathy (AMSAN) and acute motor axonal neuropathy (AMAN). The Fisher syndrome of ophthalmoplegia, ataxia and areflexia is the most striking of several related conditions. Significant antecedent events include Campylobacter jejuni (4-66%), cytomegalovirus (5-15%), Epstein-Barr virus (2-10%), and Mycoplasma pneumoniae (1-5%) infections. These infections are not uniquely associated with any clinical subtype but severe axonal degeneration is more common following C. jejuni and severe sensory impairment following cytomegalovirus. Strong evidence supports an important role for antibodies to gangliosides in pathogenesis. In particular antibodies to ganglioside GM1 are present in 14-50% of patients with GBS, and are more common in cases with severe axonal degeneration associated with any subtype. Antibodies to ganglioside GQ1b are very closely associated with Fisher syndrome, its formes frustes and related syndromes. Ganglioside-like epitopes exist in the bacterial wall of C. jejuni. Infection by this and other organisms triggers an antibody response in patients with GBS but not in those with uncomplicated enteritis. The development of GBS is likely to be a consequence of special properties of the infecting organism, since some strains such as Penner 0:19 and 0:41 are particularly associated with GBS but not with enteritis. It is also likely to be a consequence of the immunogenetic background of the patient since few patients develop GBS after infection even with one of these strains. Attempts to match the subtypes of GBS to the fine specificity of anti-ganglioside antibodies and to functional effects in experimental models continue but have not yet fully explained the pathogenesis. T cells are also involved in the pathogenesis of most or perhaps all forms of GBS. T cell responses to any of three myelin proteins, P2, PO and PMP22, are sufficient to induce experimental autoimmune neuritis. Activated T cells are present in the circulation in the acute stage, up-regulate matrix metalloproteinases, cross the blood-nerve barrier and encounter their cognate antigens. Identification of the specificity of these T cell responses is still at a preliminary stage. The invasion of intact myelin sheaths by activated macrophages is difficult to explain according to a purely T cell mediated mechanism. The different patterns of GBS are probably due to the diverse interplay between antibodies and T cells of differing specificities.