[Show abstract][Hide abstract] ABSTRACT: Introduction
Neurodegeneration is a widely accepted contributor to the development of long-term disability in multiple sclerosis (MS). While current therapies in MS predominantly target inflammation and reduce relapse rate they have been less effective at preventing long-term disability. The identification and evaluation of effective neuroprotective therapies within a trial paradigm are key unmet needs. Emerging evidence supports amiloride, a licenced diuretic, as a neuroprotective agent in MS through acid sensing ion channel blockade. Optic neuritis (ON) is a common manifestation of MS with correlates of inflammation and neurodegeneration measurable within the visual pathways. Amiloride Clinical Trial In Optic Neuritis (ACTION) will utilise a multimodal approach to assess the neuroprotective efficacy of amiloride in acute ON.
Methods and analysis
46 patients will be recruited within 28 days from onset of ON visual symptoms and randomised on a 1:1 basis to placebo or amiloride 10 mg daily. Double-blinded treatment groups will be balanced for age, sex and visual loss severity by a random-deterministic minimisation algorithm. The primary objective is to demonstrate that amiloride is neuroprotective in ON as assessed by scanning laser polarimetry of the peripapillary retinal nerve fibre layer (RNFL) thickness at 6 months in the affected eye compared to the unaffected eye at baseline. RNFL in combination with further retinal measures will also be assessed by optical coherence tomography. Secondary outcome measures on brain MRI will include cortical volume, diffusion-weighted imaging, resting state functional MRI, MR spectroscopy and magnetisation transfer ratio. In addition, high and low contrast visual acuity, visual fields, colour vision and electrophysiology will be assessed alongside quality of life measures.
Ethics and dissemination
Ethical approval was given by the south central Oxford B research ethics committee (REC reference: 13/SC/0022). The findings from ACTION will be disseminated through peer-reviewed publications and at scientific conferences.
Trial registration number
EudraCT2012-004980-39, ClinicalTrials.gov Identifier: NCT01802489.
[Show abstract][Hide abstract] ABSTRACT: Two decades of clinical experience with immunomodulatory treatments for multiple sclerosis point to distinct immunological pathways that drive disease relapses and progression. In light of this, we discuss our current understanding of multiple sclerosis immunopathology, evaluate long-standing hypotheses regarding the role of the immune system in the disease and delineate key questions that are still unanswered. Recent and anticipated advances in the field of immunology, and the increasing recognition of inflammation as an important component of neurodegeneration, are shaping our conceptualization of disease pathophysiology, and we explore the potential implications for improved healthcare provision to patients in the future.
No preview · Article · Aug 2015 · Nature Reviews Immunology
[Show abstract][Hide abstract] ABSTRACT: To assess factors influencing the success of whole-genome sequencing for mainstream clinical diagnosis, we sequenced 217 individuals from 156 independent cases or families across a broad spectrum of disorders in whom previous screening had identified no pathogenic variants. We quantified the number of candidate variants identified using different strategies for variant calling, filtering, annotation and prioritization. We found that jointly calling variants across samples, filtering against both local and external databases, deploying multiple annotation tools and using familial transmission above biological plausibility contributed to accuracy. Overall, we identified disease-causing variants in 21% of cases, with the proportion increasing to 34% (23/68) for mendelian disorders and 57% (8/14) in family trios. We also discovered 32 potentially clinically actionable variants in 18 genes unrelated to the referral disorder, although only 4 were ultimately considered reportable. Our results demonstrate the value of genome sequencing for routine clinical diagnosis but also highlight many outstanding challenges.
[Show abstract][Hide abstract] ABSTRACT: In this issue, Sorbara etal. (2014) demonstrate that axonal transport impairment is an early feature of neurodegeneration in multiple sclerosis models. This transport deficit is reversible by anti-inflammatory intervention but, if untreated, can contribute to late-stage axonal dystrophy. In this issue Sorbara etal. (2014) demonstrate that axonal transport impairment is an early feature of neurodegeneration in multiple sclerosis models. This transport deficit is reversible by anti-inflammatory intervention but, if untreated, can contribute to late-stage axonal dystrophy.
[Show abstract][Hide abstract] ABSTRACT: Methods ACTION is a phase II randomised controlled trial of amiloride vs placebo in patients with acute optic neuritis, recruited within 28 days of onset. The primary outcome measure is comparison of 6 month retinal nerve fibre layer thickness between the affected and unaffected eye. Participants undergo OCT and GDx, high and low contrast visual acuity, colour vision, Humphrey visual fields, PERG, VEP, and MRI brain.
Results 14 patients have been recruited from 47 referrals. Mean time from onset of symptoms to commencing the study drug is 14.7 days, median 13. Mean visual acuity in the affected eye is 50 letters (6/60), median 64 (6/30). 7 patients had T2 white matter lesions on baseline MRI imaging. One patient had a pre-existing diagnosis of multiple sclerosis.
Conclusions Recruiting to clinical trials in acute optic neuritis is challenging but feasible. Ongoing and future neuroprotective trials in optic neuritis require a robust and motivated network of clinicians and researchers recognising the “window of opportunity” to facilitate timely referral.
No preview · Article · Sep 2014 · Journal of Neurology Neurosurgery & Psychiatry
[Show abstract][Hide abstract] ABSTRACT: The recent HIV-1 vaccine failures highlight the need to better understand virus-host interactions. One key question is why CD8(+) T cell responses to two HIV-Gag regions are uniquely associated with delayed disease progression only in patients expressing a few rare HLA class I variants when these regions encode epitopes presented by ∼30 more common HLA variants. By combining epitope processing and computational analyses of the two HIV subtypes responsible for ∼60% of worldwide infections, we identified a hitherto unrecognized adaptation to the antigen-processing machinery through substitutions at subtype-specific motifs. Multiple HLA variants presenting epitopes situated next to a given subtype-specific motif drive selection at this subtype-specific position, and epitope abundances correlate inversely with the HLA frequency distribution in affected populations. This adaptation reflects the sum of intrapatient adaptations, is predictable, facilitates viral subtype diversification, and increases global HIV diversity. Because low epitope abundance is associated with infrequent and weak T cell responses, this most likely results in both population-level immune evasion and inadequate responses in most people vaccinated with natural HIV-1 sequence constructs. Our results suggest that artificial sequence modifications at subtype-specific positions in vitro could refocus and reverse the poor immunogenicity of HIV proteins.
[Show abstract][Hide abstract] ABSTRACT: Multiple sclerosis (MS) is the most frequent chronic inflammatory disease of the CNS, and imposes major burdens on young lives. Great progress has been made in understanding and moderating the acute inflammatory components of MS, but the pathophysiological mechanisms of the concomitant neurodegeneration-which causes irreversible disability-are still not understood. Chronic inflammatory processes that continuously disturb neuroaxonal homeostasis drive neurodegeneration, so the clinical outcome probably depends on the balance of stressor load (inflammation) and any remaining capacity for neuronal self-protection. Hence, suitable drugs that promote the latter state are sorely needed. With the aim of identifying potential novel therapeutic targets in MS, we review research on the pathological mechanisms of neuroaxonal dysfunction and injury, such as altered ion channel activity, and the endogenous neuroprotective pathways that counteract oxidative stress and mitochondrial dysfunction. We focus on mechanisms inherent to neurons and their axons, which are separable from those acting on inflammatory responses and might, therefore, represent bona fide neuroprotective drug targets with the capability to halt MS progression.
No preview · Article · Mar 2014 · Nature Reviews Neurology
[Show abstract][Hide abstract] ABSTRACT: Although TNF antagonists are efficacious in treating a range of autoimmune conditions, they exacerbate or even promote multiple sclerosis (MS) - a clinical finding that has been a conundrum for over a decade and has been a source of debate regarding the role of these drugs and of TNF signaling in the development of demyelinating disease. Recent work investigating the functional consequences of MS-associated genetic variation in the gene encoding TNFR1 has demonstrated that genetic risk drives the production of a novel, endogenous TNF antagonist. This mirrors the clinical experience with the drugs and indicates that the net effect of TNF function in MS development is a protective one, warranting a re-evaluation of the studies that have contributed to our understanding of TNF signaling in inflammation, immunoregulation and neuroprotection, to determine how future research can be directed towards targeting this pathway for therapeutic benefit.
No preview · Article · Sep 2013 · Pharmacogenomics
[Show abstract][Hide abstract] ABSTRACT: In recent years, multiple sclerosis (MS) research has progressed on several fronts, prompting numerous clinical trials, primarily for immunotherapeutics. Although several new therapies have been disappointing and some were revealed to have devastating side effects, others have shown benefits and all have generated valuable knowledge about the progression of MS, the key contributors to pathogenesis, and on natural surveillance mechanisms for brain infections. This makes now a useful time to take stock of recent advances in developing MS treatments and consider new approaches for adding information where the gaps are greatest - mainly in understanding the degenerative processes responsible for most of the long-term disability. Here, we summarize currently accepted therapeutic principles and the drugs in late stages of development, as well as spotlighting potential novel openings for future research.
No preview · Article · Apr 2013 · Trends in Molecular Medicine
[Show abstract][Hide abstract] ABSTRACT: Human anti-glomerular basement membrane (GBM) disease strongly associates with HLA-DRB1*15:01. The target autoantigen in this disease is the noncollagenous domain of the α3 chain of type IV collagen, α3(IV)NC1, but critical early T cell epitopes presented by this human MHC class II molecule are unknown. Here, by immunizing HLA-DRB1*15:01 transgenic mice with whole recombinant α3(IV)NC1 and with overlapping α3(IV)NC1 peptides, we defined a HLA-DRB1*15:01-restricted α3(IV)NC1 T cell epitope (α3) with four critical residues. This peptide was not immunogenic in HLA-DRB1*01:01 transgenic or C57BL/6 mice. The T cell epitope is naturally processed from α3(IV)NC1. CD4 T cell clones, generated from HLA-DRB1*15:01 transgenic mice and specific for α3, transferred disease into naive HLA-DRB1*15:01 transgenic mice, evidenced by the development of necrotizing crescentic GN, albuminuria, renal impairment, and accumulation of CD4 T cells and macrophages in glomeruli. Because Fcγ receptors are implicated in disease susceptibility, we crossed HLA transgenic mice onto an FcγRIIb-deficient background. Immunization with either α3 or α3(IV)NC1 induced GN in HLA-DRB1*15:01 transgenic FcγRIIb-deficient mice, but HLA-DRB1*01:01 transgenic FcγRIIb-deficient mice were unaffected. Taken together, these results demonstrate that the HLA-DRB1*15:01-restricted T cell epitope α3 can induce T cell responses and injury in anti-GBM GN.
Full-text · Article · Feb 2013 · Journal of the American Society of Nephrology
[Show abstract][Hide abstract] ABSTRACT: Neurodegeneration is the main cause for permanent disability in multiple sclerosis. The effect of current immunomodulatory treatments on neurodegeneration is insufficient. Therefore, direct neuroprotection and myeloprotection remain an important therapeutic goal. Targeting acid-sensing ion channel 1 (encoded by the ASIC1 gene), which contributes to the excessive intracellular accumulation of injurious Na(+) and Ca(2+) and is over-expressed in acute multiple sclerosis lesions, appears to be a viable strategy to limit cellular injury that is the substrate of neurodegeneration. While blockade of ASIC1 through amiloride, a potassium sparing diuretic that is currently licensed for hypertension and congestive cardiac failure, showed neuroprotective and myeloprotective effects in experimental models of multiple sclerosis, this strategy remains untested in patients with multiple sclerosis. In this translational study, we tested the neuroprotective effects of amiloride in patients with primary progressive multiple sclerosis. First, we assessed ASIC1 expression in chronic brain lesions from post-mortem of patients with progressive multiple sclerosis to identify the target process for neuroprotection. Second, we tested the neuroprotective effect of amiloride in a cohort of 14 patients with primary progressive multiple sclerosis using magnetic resonance imaging markers of neurodegeneration as outcome measures of neuroprotection. Patients with primary progressive multiple sclerosis underwent serial magnetic resonance imaging scans before (pretreatment phase) and during (treatment phase) amiloride treatment for a period of 3 years. Whole-brain volume and tissue integrity were measured with high-resolution T(1)-weighted and diffusion tensor imaging. In chronic brain lesions of patients with progressive multiple sclerosis, we demonstrate an increased expression of ASIC1 in axons and an association with injury markers within chronic inactive lesions. In patients with primary progressive multiple sclerosis, we observed a significant reduction in normalized annual rate of whole-brain volume during the treatment phase, compared with the pretreatment phase (P = 0.018, corrected). Consistent with this reduction, we showed that changes in diffusion indices of tissue damage within major clinically relevant white matter (corpus callosum and corticospinal tract) and deep grey matter (thalamus) structures were significantly reduced during the treatment phase (P = 0.02, corrected). Our results extend evidence of the contribution of ASIC1 to neurodegeneration in multiple sclerosis and suggest that amiloride may exert neuroprotective effects in patients with progressive multiple sclerosis. This pilot study is the first translational study on neuroprotection targeting ASIC1 and supports future randomized controlled trials measuring neuroprotection with amiloride in patients with multiple sclerosis.
[Show abstract][Hide abstract] ABSTRACT: Microscopic polyangiitis is an autoimmune small-vessel vasculitis that often manifests as focal and necrotizing glomerulonephritis and renal failure. Antineutrophil cytoplasmic Abs (ANCAs) specific for myeloperoxidase (MPO) play a role in this disease, but the role of autoreactive MPO-specific CD4(+) T cells is uncertain. By screening overlapping peptides of 20 amino acids spanning the MPO molecule, we identified an immunodominant MPO CD4(+) T-cell epitope (MPO(409-428)). Immunizing C57BL/6 mice with MPO(409-428) induced focal necrotizing glomerulonephritis similar to that seen after whole MPO immunization, when MPO was deposited in glomeruli. Transfer of an MPO(409-428)-specific CD4(+) T-cell clone to Rag1(-/-) mice induced focal necrotizing glomerulonephritis when glomerular MPO deposition was induced either by passive transfer of MPO-ANCA and LPS or by planting MPO(409-428) conjugated to a murine antiglomerular basement membrane mAb. MPO(409-428) also induced biologically active anti-MPO Abs in mice. The MPO(409-428) epitope has a minimum immunogenic core region of 11 amino acids, MPO(415-426), with several critical residues. ANCA-activated neutrophils not only induce injury but lodged the autoantigen MPO in glomeruli, allowing autoreactive anti-MPO CD4(+) cells to induce delayed type hypersensitivity-like necrotizing glomerular lesions. These studies identify an immunodominant MPO T-cell epitope and redefine how effector responses can induce injury in MPO-ANCA-associated microscopic polyangiitis.
Full-text · Article · Sep 2012 · Proceedings of the National Academy of Sciences
[Show abstract][Hide abstract] ABSTRACT: Although there has been much success in identifying genetic variants associated with common diseases using genome-wide association studies (GWAS), it has been difficult to demonstrate which variants are causal and what role they have in disease. Moreover, the modest contribution that these variants make to disease risk has raised questions regarding their medical relevance. Here we have investigated a single nucleotide polymorphism (SNP) in the TNFRSF1A gene, that encodes tumour necrosis factor receptor 1 (TNFR1), which was discovered through GWAS to be associated with multiple sclerosis (MS), but not with other autoimmune conditions such as rheumatoid arthritis, psoriasis and Crohn’s disease. By analysing MS GWAS data in conjunction with the 1000 Genomes Project data we provide genetic evidence that strongly implicates this SNP, rs1800693, as the causal variant in the TNFRSF1A region. We further substantiate this through functional studies showing that the MS risk allele directs expression of a novel, soluble form of TNFR1 that can block TNF. Importantly, TNF-blocking drugs can promote onset or exacerbation of MS, but they have proven highly efficacious in the treatment of autoimmune diseases for which there is no association with rs1800693. This indicates that the clinical experience with these drugs parallels the disease association of rs1800693, and that the MS-associated TNFR1 variant mimics the effect of TNF-blocking drugs. Hence, our study demonstrates that clinical practice can be informed by comparing GWAS across common autoimmune diseases and by investigating the functional consequences of the disease-associated genetic variation.
[Show abstract][Hide abstract] ABSTRACT: Multiple sclerosis (MS) is a disabling autoimmune disease of the central nervous system, which affects approximately 0.1% of the population with variable degrees of severity. Disease susceptibility is jointly determined by genetic predisposition and environmental contribution. However, as only a handful of genetic risk factors have been investigated beyond initial genome-wide association studies and environmental factors are largely unidentified, the exact mechanism of how these associations interact remains speculative. Our current understanding of this complex and heterogeneous disease has been advanced by experimental data obtained from animal modeling, with particular focus on the mouse MS model, experimental autoimmune encephalomyelitis. Manipulation of the mouse genome to study genetic risk factors has largely proved informative, but it also has limitations. Integration effects of transgene insertion, gene copy number, and expression variation, as well as differences in regulatory elements between mouse and human, are some of the hurdles faced when using such models to understand human gene variants in mice. Furthermore, as the list of MS disease-associated genetic variants continues to increase, so does the demand to find new approaches to study them. A new generation of humanized mice aims to tighten the gap between mouse and human, such that MS-associated genetic variants can be modeled more physiologically and systematically.
No preview · Article · Jul 2012 · Immunological Reviews
[Show abstract][Hide abstract] ABSTRACT: The immune system has crucial roles in the pathogenesis of multiple sclerosis. While the adaptive immune cell subsets, T and B cells, have been the main focus of immunological research in multiple sclerosis, it is now important to realize that the innate immune system also has a key involvement in regulating autoimmune responses in the central nervous system. Natural killer cells are innate lymphocytes that play vital roles in a diverse range of infections. There is evidence that they influence a number of autoimmune conditions. Recent studies in multiple sclerosis and its murine model, experimental autoimmune encephalomyelitis, are starting to provide some understanding of the role of natural killer cells in regulating inflammation in the central nervous system. Natural killer cells express a diverse range of polymorphic cell surface receptors, which interact with polymorphic ligands; this interaction controls the function and the activation status of the natural killer cell. In this review, we discuss evidence for the role of natural killer cells in multiple sclerosis and experimental autoimmune encephalomyelitis. We consider how a change in the balance of signals received by the natural killer cell influences its involvement in the ensuing immune response, in relation to multiple sclerosis.
[Show abstract][Hide abstract] ABSTRACT: Orexin/hypocretin (orx/hcrt) neurons are thought to ensure that reward-seeking is accompanied by alertness, but the underlying circuit organization is unclear. Reports of differential regulation of lateral versus medial orx/hcrt cells produced a hypothesis of 'efferent dichotomy', in which lateral orx/hcrt cells innervate the ventral tegmental area (VTA) and control reward, while medial orx/hcrt cells innervate locus coeruleus (LC) and control arousal. Two distinct types of orx/hcrt cells also emerged from analysis of intrinsic and input-driven single-cell electrical activity. To examine the projections of these emerging orx/hcrt subtypes to LC and VTA, we injected retrograde tracer into these regions in the mouse brain in vivo, and then examined the properties of tracer-containing orx/hcrt cells in hypothalamic slices. VTA- and LC-projecting orx/hcrt cells were found across the entire orx/hcrt field, including the zona incerta, perifornical area, dorsomedial/anterior and lateral hypothalamus. Within these areas, orx/hcrt cells had similar probabilities of projecting to VTA or LC. Examination of lateral versus medial sections revealed that VTA and LC received inputs from both lateral and medial orx/hcrt cells, but, unexpectedly, lateral orx/hcrt cells were more likely to project to LC than medial orx/hcrt cells. Finally, patch-clamp recordings revealed that VTA and LC received projections from both electrical classes of orx/hcrt cells, which had similar likelihoods of projecting to VTA or LC. Contrary to previous predictions, our data suggest that medial and lateral orx/hcrt cells, and the different electrical and morphological subclasses of orx/hcrt cells identified to date, send projections to both LC and VTA.
Full-text · Article · Apr 2012 · European Journal of Neuroscience