Stefan Blum

Use and monitoring of low dose rituximab in myasthenia gravis

Background Myasthenia gravis is an autoimmune disorder of the neuromuscular junction. Rituximab (RTX), a monoclonal antibody to CD20, leads to B lymphocyte depletion and has been used in some autoimmune disorders, including small case series of myasthenia gravis patients. Methods A retrospective analysis was performed of all patients with acetylcholine receptor (AChR) (11 subjects) or muscle specific kinase antibody (MuSK) positive myasthenia gravis (three subjects), who had been treated with RTX in Brisbane, Australia. In most patients 1 g of RTX, in two divided doses, was given. Patients were monitored by serial clinical assessments, flow cytometry of peripheral blood B lymphocytes and antibody testing. Results RTX led to a significant improvement in symptoms in 11 of 14 patients. Doses of immunosuppressive medications were able to be reduced in 12 of 14 patients but medications could be completely ceased in only one patient. A demonstrable reduction of autoantibody levels was found in only three AChR positive patients and one MuSK positive patient, independent of clinical improvement. Peripheral blood B lymphocyte depletion was achieved in 13 out of 14 patients. B lymphocyte recovery occurred between 9 and 30 months post RTX (median 12.3 months) and was consistently associated with worsening of clinical symptoms. Conclusion Rituximab at a dose of 1 g appears to be beneficial in the treatment of patients with severe myasthenia gravis. Serial monitoring of peripheral blood B lymphocytes appears to be useful in guiding the need for further RTX therapy.

Guillain-Barré Syndrome: Modern Theories of Etiology

Guillain-Barré syndrome (GBS) is a classic failure of the immune system with a life-threatening attack upon a critical self-component. The active phase of the disease is short, concordant with the latency of a primary adaptive immune response. Triggers for GBS include infection and (rarely) vaccination; cross-reactivity between infectious and neural epitopes has been well demonstrated, particularly for Campylobacter jejuni and motor axonal forms of GBS in which non-protein gangliosides are antigenic. Most people are probably exposed to a GBS trigger, but only rarely does the disease develop. We propose that GBS illustrates competing determinants of the immune system’s decision about whether to mount a response, and that in unlucky affected individuals, co-presentation of cross-reactive antigens with danger signals activating pattern-recognition receptors overcomes normal self-recognition such that a primary response is initiated that attacks the nerve. Then, in most cases of GBS, the response rapidly turns off, and second attacks rarely occur. This suggests active restoration of tolerance, and specific privileged site attributes of nerve and declining danger signals as the trigger wanes may contribute to this restoration. Standard immunosuppression has not been effective in GBS. We suggest this is because immune tolerance is already being restored by the time such therapies are initiated. This in turn suggests that improvements in GBS outcomes are likely to come from better protection of the nerve cells under attack while normal resumption of tolerance is permitted to proceed rather than exploring more aggressive immunosuppressive approaches.

Genetics of Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP): current knowledge and future directions

Guillain‐Barré syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) are thought to be autoimmune diseases. There have been many attempts to find a human leukocyte antigen (HLA) association with GBS and CIDP with little success. There have been studies of other plausible genes in GBS and CIDP and the role of these genes in GBS and CIDP and the data from these genetic studies is reviewed. Some of the genes that have been studied are immune related and some others have nervous system effects. The studies are limited by small numbers. Some of the genes show association with disease severity rather than disease susceptibility. The need for more detailed molecular studies of the role of HLA molecules and the need for modern genetic approaches to GBS and CIDP are explained.

Fibronectin synthesis by activated T lymphocytes: up-regulation of a surface-associated isoform with signalling function

Fibronectin (FN) is a major constituent of the extracellular matrix. We now provide evidence for a surface‐associated isoform of FN that is synthesized by T cells upon activation. The T‐cell‐derived FN has an unusual splice pattern: an additional domain, EDB, is produced whereas sequences within another domain, IIICS, are spliced out. CS1, the binding domain for very late antigen‐4 (VLA‐4), however, is still generated. To study the potential function of surface‐associated FN its synthesis was down‐regulated by an antisense oligonucleotide, then proliferation of T cells was induced by cross‐linked anti‐CD3. Proliferation was reduced as was expression of CD25. Moreover, when T cells were cultured in high density, the synthetic peptide QILDVPST, corresponding to CS1, inhibited proliferation, as did antibodies to VLA‐4. We propose that surface‐associated FN is a ligand for VLA‐4, which by binding to VLA‐4 on an adjacent cell, provides a costimulatory signal, thus sustaining T‐cell proliferation.

Common polymorphisms in dystonia-linked genes and susceptibility to the sporadic primary dystonias.

Genes involved in familial dystonia syndromes (DYT genes) are ideal candidates for investigating whether common genetic variants influence the susceptibility to sporadic primary dystonia. To date, there have been few candidate gene studies for primary dystonia and only two DYT genes, TOR1A and THAP1, have been assessed. We therefore employed a haplotype-tagging strategy to comprehensively assess if common polymorphisms in eight DYT genes (TOR1A, TAF1, GCH1, THAP1, MR-1 (PNKD), SGCE, ATP1A3 and PRKRA) confer risk for sporadic primary dystonia. The 230 primary dystonia cases were matched for age and gender to 228 controls, recruited from movement disorder clinics in Brisbane, Australia and the Australian electoral roll. All subjects were genotyped for 56 tagging SNPs and genotype associations were investigated. Modest genotypic associations (P<0.05) were observed for three GCH1 SNPs (rs12147422, rs3759664 and rs10483639) when comparing all cases against controls. Associations were also seen when the cases were stratified based on presentation. Overall, our findings do not support the hypothesis that common TOR1A variants affect susceptibility for sporadic primary dystonia, and that it is unlikely that common variants around the DYT genes confer substantial risk for sporadic primary dystonia. Further work is warranted to follow up the GCH1 SNPs and the subgroup analyses.

Cognitive and social functioning deficits after anti-N-methyl-D-aspartate receptor encephalitis: an exploratory case series

BACKGROUND Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a recently described life-threatening autoimmune disorder associated with a characteristic multi-stage neuropsychiatric syndrome. Although it is known that the majority of patients experience neuropsychological disturbance post-treatment, some aspects of the cognitive profile remain unclear. METHODS This study sought to investigate patterns of cognitive functioning in a sample of anti-NMDAR encephalitis patients. Seven (6F:1M; mean age, 26.4 years; range, 16-37 years) treated patients completed a comprehensive set of neurocognitive and social functioning measures. Performance was analyzed using normative data (where available), and comparison with matched controls (10F:4M; mean age, 25.8 years; range, 16-38 years). RESULTS Individual cognitive profiles ranged from within normal limits to extensive dysfunction. Relative to controls, the patient groups performance was affected in the domains of verbal/ visual memory, working memory, attention, processing speed, executive functioning, and social cognition. The patient group also reported significantly higher levels of anxiety compared to controls. CONCLUSIONS These results add to the accumulating evidence that neurocognitive deficits, consistent with the distribution and functions of the NMDAR system can persist during recovery from anti-NMDAR encephalitis. This is the first study to provide evidence of performance decrements on measures of social cognition, including some involving theory of mind. (JINS, 2016, 22, 828-838).

Autoimmune encephalitis: Autoimmune encephalitis

Over the past decade, the clinical spectrum of autoimmune encephalitis has expanded with the emergence of several new clinicopathological entities. In particular, autoimmune encephalitis has recently been described in association with antibodies to surface receptors and ion channels on neurological tissues. Greater clinician awareness has resulted in autoimmune encephalitis being increasingly recognised in patients with unexplained neurological and psychiatric symptoms and signs. The clinical spectrum of presentations, as well as our understanding of disease mechanisms and treatment regimens, is rapidly developing. An understanding of these conditions is important to all subspecialties of Internal Medicine, including neurology and clinical immunology, psychiatry, intensive care and rehabilitation medicine. This review provides a contemporary overview of the aetiology, investigations and treatment of the most recently described autoimmune encephalitides.

Clinical features of patients with Guillain‐Barré syndrome at seven hospitals on the East Coast of Australia

To document the clinical features of Guillain‐Barré syndrome (GBS) in Australia, we performed a retrospective analysis of all patients admitted to several hospitals along the East Coast of Australia from 2000 to 2012. Using hospital records, we reviewed all patients with a diagnosis of GBS admitted to seven hospitals. From these, we report information of subjects who fulfilled standard diagnostic criteria. We excluded patients where inadequate information was available or who were under the age of 18. We report the features of 335 patients, in 228 of whom neurophysiological data were available. There were 168 cases of acute inflammatory demyelinating polyneuropathy (AIDP), 17 of acute motor axonal neuropathy (AMAN), 4 of acute motor and sensory axonal neuropathy (AMSAN), and 35 of Miller‐Fisher syndrome (MFS). The median age at onset was 52.5 years (18–89 years) with a male : female ratio of 1.61 : 1. Upper respiratory tract infections were the most frequently identified trigger (151 subjects, 44.5%). Most patients were severely affected, with 42.7% of subjects bedbound, and an additional 24% requiring ventilatory support. GBS affects adults of all ages and usually follows a severe clinical course. In contrast to other autoimmune diseases, males are more frequently affected. A wide variety of triggering factors leads to a relatively stereotypical clinical syndrome. The most common variant of GBS in Australia is AIDP. This study shows that the clinical features of GBS in Australia are similar to that previously reported and confirms the male predominance, increased incidence with age, and frequent evidence of peripheral nerve demyelination as features of GBS.

Incidence and prevalence of NMOSD in Australia and New Zealand

Objectives We have undertaken a clinic-based survey of neuromyelitis optica spectrum disorders (NMOSDs) in Australia and New Zealand to establish incidence and prevalence across the region and in populations of differing ancestry. Background NMOSD is a recently defined demyelinating disease of the central nervous system (CNS). The incidence and prevalence of NMOSD in Australia and New Zealand has not been established. Methods Centres managing patients with demyelinating disease of the CNS across Australia and New Zealand reported patients with clinical and laboratory features that were suspicious for NMOSD. Testing for aquaporin 4 antibodies was undertaken in all suspected cases. From this group, cases were identified who fulfilled the 2015 Wingerchuk diagnostic criteria for NMOSD. A capture–recapture methodology was used to estimate incidence and prevalence, based on additional laboratory identified cases. Results NMOSD was confirmed in 81/170 (48%) cases referred. Capture–recapture analysis gave an adjusted incidence estimate of 0.37 (95% CI 0.35 to 0.39) per million per year and a prevalence estimate for NMOSD of 0.70 (95% CI 0.61 to 0.78) per 100 000. NMOSD was three times more common in the Asian population (1.57 (95% CI 1.15 to 1.98) per 100 000) compared with the remainder of the population (0.57 (95% CI 0.50 to 0.65) per 100 000). The latitudinal gradient evident in multiple sclerosis was not seen in NMOSD. Conclusions NMOSD incidence and prevalence in Australia and New Zealand are comparable with figures from other populations of largely European ancestry. We found NMOSD to be more common in the population with Asian ancestry.

Killer immunoglobulin-like receptor and their HLA ligands in Guillain-Barré Syndrome

Guillain-Barré Syndrome (GBS) is an inflammatory neuropathy that occurs in some individuals after exposure to an infectious illness. We investigated the role of Killer-immunoglobulin-like receptors (KIR) and their HLA ligands as potential genetic factors in the pathogenesis of GBS. These receptors are involved in the innate immune response to infections. Whilst no significant differences in the frequencies KIR genes were found, HLA-C2 and HLA-B Bw4-T were more frequent in subjects with GBS than controls (p<0.001). The inhibitory pairs KIR-2DL2/HLA-C2 and KIR-3DL1/HLA-B Bw4-T were more frequent in GBS than controls (all p<0.005). We propose that NK cell inhibition is an important factor in the pathogenesis of GBS.