Publications by authors named "Simon Rothwell"

21 Publications

  • Page 1 of 1

The myositis clinical phenotype associated with anti-Zo autoantibodies: a case series of nine UK patients.

Rheumatology (Oxford) 2020 07;59(7):1626-1631

Department of Pharmacy and Pharmacology, The University of Bath, Bath.

Objectives: It has been over 10 years since the first report of autoantibodies directed against phenylalanyl tRNA synthetase (anti-Zo) in a patient with features of the anti-synthetase syndrome. In that time no further cases have been published. Here we aim to characterize more fully the clinical phenotype of anti-Zo-associated myositis by describing the clinical features of nine patients.

Methods: Anti-Zo was identified by protein-immunoprecipitation in patients referred for extended spectrum myositis autoantibody testing at our laboratory. Results were confirmed by immunodepletion using a reference serum. Medical records were retrospectively reviewed to provide detailed information of the associated clinical phenotype for all identified patients. Where possible, HLA genotype was imputed using Illumina protocols.

Results: Nine patients with anti-Zo were identified. The median age at disease onset was 51 years, and six patients were female. Seven patients had evidence of inflammatory muscle disease, seven of interstitial lung disease and six of arthritis. The reported pattern of interstitial lung disease varied with usual interstitial pneumonia, non-specific interstitial pneumonia and organizing pneumonia all described. Other features of the anti-synthetase syndrome such as RP and mechanics hands were common. HLA data was available for three patients, all of whom had at least one copy of the HLA 8.1 ancestral haplotype.

Conclusion: Patients with anti-Zo presenting with features of the anti-synthetase syndrome and interstitial lung disease is a common finding. Like other myositis autoantibodies, there is likely to be a genetic association with the HLA 8.1 ancestral haplotype.
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http://dx.doi.org/10.1093/rheumatology/kez504DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7310094PMC
July 2020

Disruption of the Key Ca Binding Site in the Selectivity Filter of Neuronal Voltage-Gated Calcium Channels Inhibits Channel Trafficking.

Cell Rep 2019 Oct;29(1):22-33.e5

Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, UK. Electronic address:

Voltage-gated calcium channels are exquisitely Ca selective, conferred primarily by four conserved pore-loop glutamate residues contributing to the selectivity filter. There has been little previous work directly measuring whether the trafficking of calcium channels requires their ability to bind Ca in the selectivity filter or to conduct Ca. Here, we examine trafficking of neuronal Ca2.1 and 2.2 channels with mutations in their selectivity filter and find reduced trafficking to the cell surface in cell lines. Furthermore, in hippocampal neurons, there is reduced trafficking to the somatic plasma membrane, into neurites, and to presynaptic terminals. However, the Ca2.2 selectivity filter mutants are still influenced by auxiliary αδ subunits and, albeit to a reduced extent, by β subunits, indicating the channels are not grossly misfolded. Our results indicate that Ca binding in the pore of Ca2 channels may promote their correct trafficking, in combination with auxiliary subunits. Furthermore, physiological studies utilizing selectivity filter mutant Ca channels should be interpreted with caution.
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http://dx.doi.org/10.1016/j.celrep.2019.08.079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6899504PMC
October 2019

Genetics of idiopathic inflammatory myopathies: insights into disease pathogenesis.

Curr Opin Rheumatol 2019 11;31(6):611-616

Division of Population Health, Health Services Research & Primary Care, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.

Purpose Of Review: To review the advances that have been made in our understanding of the genetics of idiopathic inflammatory myopathies (IIM) in the past 2 years, with a particular focus on dermatomyositis and polymyositis.

Recent Findings: Fine-mapping studies in the major histocompatibility complex region in Caucasian and Korean populations have identified novel human leukocyte antigen (HLA) variants that are associated with autoantibody subgroups in IIM. Differences in HLA associations have been identified between Caucasian adult-onset and juvenile-onset patients with anti-TIF1 autoantibodies, suggesting distinct aetiologies in these patients. For some autoantibodies, the strongest associations identified are specific amino acid positions within HLA molecules, providing mechanistic insights into disease pathogenesis.A meta-analysis combining data from four seropositive rheumatic diseases identified 22 novel non-HLA associations in IIM, of which seven were previously reported at suggestive significance in IIM. A genome-wide association study conducted in the Japanese population identified a significant association with WDFY4 in patients with clinically amyopathic dermatomyositis.

Summary: Considerable progress has been made in understanding the genetics of IIM, including differences in clinical and autoantibody subgroups. As research continues, there should be a focus to increase statistical strength and precision by conducting meta-analyses and trans-ethnic studies.
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http://dx.doi.org/10.1097/BOR.0000000000000652DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6791565PMC
November 2019

Focused HLA analysis in Caucasians with myositis identifies significant associations with autoantibody subgroups.

Ann Rheum Dis 2019 07 28;78(7):996-1002. Epub 2019 May 28.

Division of Rheumatology, Department of Medicine, Karolinska University Hospital, Stockholm, Sweden.

Objectives: Idiopathic inflammatory myopathies (IIM) are a spectrum of rare autoimmune diseases characterised clinically by muscle weakness and heterogeneous systemic organ involvement. The strongest genetic risk is within the major histocompatibility complex (MHC). Since autoantibody presence defines specific clinical subgroups of IIM, we aimed to correlate serotype and genotype, to identify novel risk variants in the MHC region that co-occur with IIM autoantibodies.

Methods: We collected available autoantibody data in our cohort of 2582 Caucasian patients with IIM. High resolution human leucocyte antigen (HLA) alleles and corresponding amino acid sequences were imputed using SNP2HLA from existing genotyping data and tested for association with 12 autoantibody subgroups.

Results: We report associations with eight autoantibodies reaching our study-wide significance level of p<2.9×10. Associations with the 8.1 ancestral haplotype were found with anti-Jo-1 (HLA-B*08:01, p=2.28×10 and HLA-DRB1*03:01, p=3.25×10), anti-PM/Scl (HLA-DQB1*02:01, p=1.47×10) and anti-cN1A autoantibodies (HLA-DRB1*03:01, p=1.40×10). Associations independent of this haplotype were found with anti-Mi-2 (HLA-DRB1*07:01, p=4.92×10) and anti-HMGCR autoantibodies (HLA-DRB1*11, p=5.09×10). Amino acid positions may be more strongly associated than classical HLA associations; for example with anti-Jo-1 autoantibodies and position 74 of HLA-DRB1 (p=3.47×10) and position 9 of HLA-B (p=7.03×10). We report novel genetic associations with HLA-DQB1 anti-TIF1 autoantibodies and identify haplotypes that may differ between adult-onset and juvenile-onset patients with these autoantibodies.

Conclusions: These findings provide new insights regarding the functional consequences of genetic polymorphisms within the MHC. As autoantibodies in IIM correlate with specific clinical features of disease, understanding genetic risk underlying development of autoantibody profiles has implications for future research.
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http://dx.doi.org/10.1136/annrheumdis-2019-215046DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6585280PMC
July 2019

Genetic background may contribute to the latitude-dependent prevalence of dermatomyositis and anti-TIF1-γ autoantibodies in adult patients with myositis.

Arthritis Res Ther 2018 06 8;20(1):117. Epub 2018 Jun 8.

Centre for Epidemiology, Division of Population Health, Health Services Research & Primary Care, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, 2.706 Stopford Building, Oxford Road, Manchester, M13 9PT, UK.

Background: The prevalence of dermatomyositis (DM) versus DM and polymyositis (PM) combined has been shown to be negatively associated with latitude. This observation has been attributed to increasing exposure to ultraviolet (UV) light towards the equator. In this study, we investigated whether differing genetic background in populations could contribute to this distribution of DM.

Methods: Case data derived from the MYOGEN (Myositis Genetics Consortium) Immunochip study (n = 1769) were used to model the association of DM prevalence and DM-specific autoantibodies with latitude. Control data (n = 9911) were used to model the relationship of human leucocyte antigen (HLA) associated with DM autoantibodies and DM or PM single-nucleotide polymorphisms (suggestive significance in the Immunochip project, P < 2.25 × 10) in healthy control subjects with latitude. All variables were analysed against latitude using ordered logistic regression, adjusted for sex.

Results: The prevalence of DM, as a proportion of DM and PM combined, and the presence of anti-transcription intermediary factor 1 (anti-TIF1-γ) autoantibodies were both significantly negatively associated with latitude (OR 0.96, 95% CI 0.95-0.98, P < 0.001; and OR 0.95, 95% CI 0.92-0.99, P = 0.004, respectively). HLA alleles significantly associated with anti-Mi-2 and anti-TIF1-γ autoantibodies also were strongly negatively associated with latitude (OR 0.97, 95% CI 0.96-0.98, P < 0.001 and OR 0.98, 95% CI 0.97-0.99, P < 0.001, respectively). The frequency of five PM- or DM-associated SNPs showed a significant association with latitude (P < 0.05), and the direction of four of these associations was consistent with the latitude associations of the clinical phenotypes.

Conclusions: These results lend some support to the hypothesis that genetic background, in addition to UV exposure, may contribute to the distribution of DM.
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http://dx.doi.org/10.1186/s13075-018-1617-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5994128PMC
June 2018

Splicing variant of augments MDA5 signalling and the risk of clinically amyopathic dermatomyositis.

Ann Rheum Dis 2018 04 13;77(4):602-611. Epub 2018 Jan 13.

Laboratory for Autoimmune Diseases, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan.

Objectives: Idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of rare autoimmune diseases in which both genetic and environmental factors play important roles. To identify genetic factors of IIM including polymyositis, dermatomyositis (DM) and clinically amyopathic DM (CADM), we performed the first genome-wide association study for IIM in an Asian population.

Methods: We genotyped and tested 496 819 single nucleotide polymorphism for association using 576 patients with IIM and 6270 control subjects. We also examined the causal mechanism of disease-associated variants by in silico analyses using publicly available data sets as well as by in in vitro analyses using reporter assays and apoptosis assays.

Results: We identified a variant in that was significantly associated with CADM (rs7919656; OR=3.87; P=1.5×10). This variant had a cis-splicing quantitative trait locus (QTL) effect for a truncated isoform (tr-), with higher expression in the risk allele. Transexpression QTL analysis of this variant showed a positive correlation with the expression of NF-κB associated genes. Furthermore, we demonstrated that both WDFY4 and tr-WDFY4 interacted with pattern recognition receptors such as TLR3, TLR4, TLR9 and MDA5 and augmented the NF-κB activation by these receptors. WDFY4 isoforms also enhanced MDA5-induced apoptosis to a greater extent in the tr-WDFY4-transfected cells.

Conclusions: As CADM is characterised by the appearance of anti-MDA5 autoantibodies and severe lung inflammation, the WDFY4 variant may play a critical role in the pathogenesis of CADM.
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http://dx.doi.org/10.1136/annrheumdis-2017-212149DOI Listing
April 2018

Genetics in inclusion body myositis.

Curr Opin Rheumatol 2017 Nov;29(6):639-644

aCentre for Musculoskeletal Research, Division of Musculoskeletal and Dermatological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester bGreater Manchester Neurosciences Centre, Manchester Academic Health Science Centre, Salford Royal NHS Foundation Trust, Stott Lane, Salford cCentre for Epidemiology, Division of Population Health, Health Services Research and Primary Care, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK.

Purpose Of Review: To review the advances in our understanding of the genetics of inclusion body myositis (IBM) in the past year.

Recent Findings: One large genetic association study focusing on immune-related genes in IBM has refined the association within the human leukocyte antigen (HLA) region to HLA-DRB1 alleles, and identified certain amino acid positions in HLA-DRB1 that may explain this risk. A suggestive association with CCR5 may indicate genetic overlap with other autoimmune diseases. Sequencing studies of candidate genes involved in related neuromuscular or neurodegenerative diseases have identified rare variants in VCP and SQSTM1. Proteomic studies of rimmed vacuoles in IBM and subsequent genetic analyses of candidate genes identified rare missense variants in FYCO1. Complex, large-scale mitochondrial deletions in cytochrome c oxidase-deficient muscle fibres expand our understanding of mitochondrial abnormalities in IBM.

Summary: The pathogenesis of IBM is likely multifactorial, including inflammatory and degenerative changes, and mitochondrial abnormalities. There has been considerable progress in our understanding of the genetic architecture of IBM, using complementary genetic approaches to investigate these different pathways.
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http://dx.doi.org/10.1097/BOR.0000000000000431DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5625970PMC
November 2017

LRP1 influences trafficking of N-type calcium channels via interaction with the auxiliary αδ-1 subunit.

Sci Rep 2017 03 3;7:43802. Epub 2017 Mar 3.

Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK.

Voltage-gated Ca (Ca) channels consist of a pore-forming α1 subunit, which determines the main functional and pharmacological attributes of the channel. The Ca1 and Ca2 channels are associated with auxiliary β- and αδ-subunits. The molecular mechanisms involved in αδ subunit trafficking, and the effect of αδ subunits on trafficking calcium channel complexes remain poorly understood. Here we show that αδ-1 is a ligand for the Low Density Lipoprotein (LDL) Receptor-related Protein-1 (LRP1), a multifunctional receptor which mediates trafficking of cargoes. This interaction with LRP1 is direct, and is modulated by the LRP chaperone, Receptor-Associated Protein (RAP). LRP1 regulates αδ binding to gabapentin, and influences calcium channel trafficking and function. Whereas LRP1 alone reduces αδ-1 trafficking to the cell-surface, the LRP1/RAP combination enhances mature glycosylation, proteolytic processing and cell-surface expression of αδ-1, and also increase plasma-membrane expression and function of Ca2.2 when co-expressed with αδ-1. Furthermore RAP alone produced a small increase in cell-surface expression of Ca2.2, αδ-1 and the associated calcium currents. It is likely to be interacting with an endogenous member of the LDL receptor family to have these effects. Our findings now provide a key insight and new tools to investigate the trafficking of calcium channel αδ subunits.
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http://dx.doi.org/10.1038/srep43802DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5335561PMC
March 2017

Immune-Array Analysis in Sporadic Inclusion Body Myositis Reveals HLA-DRB1 Amino Acid Heterogeneity Across the Myositis Spectrum.

Arthritis Rheumatol 2017 05 4;69(5):1090-1099. Epub 2017 Apr 4.

Central Manchester University Hospitals NHS Foundation Trust, University of Manchester, Manchester, UK.

Objective: Inclusion body myositis (IBM) is characterized by a combination of inflammatory and degenerative changes affecting muscle. While the primary cause of IBM is unknown, genetic factors may influence disease susceptibility. To determine genetic factors contributing to the etiology of IBM, we conducted the largest genetic association study of the disease to date, investigating immune-related genes using the Immunochip.

Methods: A total of 252 Caucasian patients with IBM were recruited from 11 countries through the Myositis Genetics Consortium and compared with 1,008 ethnically matched controls. Classic HLA alleles and amino acids were imputed using SNP2HLA.

Results: The HLA region was confirmed as the most strongly associated region in IBM (P = 3.58 × 10 ). HLA imputation identified 3 independent associations (with HLA-DRB1*03:01, DRB1*01:01, and DRB1*13:01), although the strongest association was with amino acid positions 26 and 11 of the HLA-DRB1 molecule. No association with anti-cytosolic 5'-nucleotidase 1A-positive status was found independent of HLA-DRB1*03:01. There was no association of HLA genotypes with age at onset of IBM. Three non-HLA regions reached suggestive significance, including the chromosome 3 p21.31 region, an established risk locus for autoimmune disease, where a frameshift mutation in CCR5 is thought to be the causal variant.

Conclusion: This is the largest, most comprehensive genetic association study to date in IBM. The data confirm that HLA is the most strongly associated region and identifies novel amino acid associations that may explain the risk in this locus. These amino acid associations differentiate IBM from polymyositis and dermatomyositis and may determine properties of the peptide-binding groove, allowing it to preferentially bind autoantigenic peptides. A novel suggestive association within the chromosome 3 p21.31 region suggests a role for CCR5.
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http://dx.doi.org/10.1002/art.40045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5516174PMC
May 2017

Proteolytic maturation of αδ represents a checkpoint for activation and neuronal trafficking of latent calcium channels.

Elife 2016 10 26;5. Epub 2016 Oct 26.

Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom.

The auxiliary αδ subunits of voltage-gated calcium channels are extracellular membrane-associated proteins, which are post-translationally cleaved into disulfide-linked polypeptides α and δ. We now show, using αδ constructs containing artificial cleavage sites, that this processing is an essential step permitting voltage-dependent activation of plasma membrane N-type (Ca2.2) calcium channels. Indeed, uncleaved α2δ inhibits native calcium currents in mammalian neurons. By inducing acute cell-surface proteolytic cleavage of αδ, voltage-dependent activation of channels is promoted, independent from the trafficking role of αδ. Uncleaved αδ does not support trafficking of Ca2.2 channel complexes into neuronal processes, and inhibits Ca entry into synaptic boutons, and we can reverse this by controlled intracellular proteolytic cleavage. We propose a model whereby uncleaved αδ subunits maintain immature calcium channels in an inhibited state. Proteolytic processing of αδ then permits voltage-dependent activation of the channels, acting as a checkpoint allowing trafficking only of mature calcium channel complexes into neuronal processes.
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http://dx.doi.org/10.7554/eLife.21143DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5092059PMC
October 2016

The CaVβ Subunit Protects the I-II Loop of the Voltage-gated Calcium Channel CaV2.2 from Proteasomal Degradation but Not Oligoubiquitination.

J Biol Chem 2016 09 3;291(39):20402-16. Epub 2016 Aug 3.

From the Department of Neuroscience, Physiology and Pharmacology, University College London, Gower St., London WC1E 6BT, United Kingdom

CaVβ subunits interact with the voltage-gated calcium channel CaV2.2 on a site in the intracellular loop between domains I and II (the I-II loop). This interaction influences the biophysical properties of the channel and leads to an increase in its trafficking to the plasma membrane. We have shown previously that a mutant CaV2.2 channel that is unable to bind CaVβ subunits (CaV2.2 W391A) was rapidly degraded (Waithe, D., Ferron, L., Page, K. M., Chaggar, K., and Dolphin, A. C. (2011) J. Biol. Chem. 286, 9598-9611). Here we show that, in the absence of CaVβ subunits, a construct consisting of the I-II loop of CaV2.2 was directly ubiquitinated and degraded by the proteasome system. Ubiquitination could be prevented by mutation of all 12 lysine residues in the I-II loop to arginines. Including a palmitoylation motif at the N terminus of CaV2.2 I-II loop was insufficient to target it to the plasma membrane in the absence of CaVβ subunits even when proteasomal degradation was inhibited with MG132 or ubiquitination was prevented by the lysine-to-arginine mutations. In the presence of CaVβ subunit, the palmitoylated CaV2.2 I-II loop was protected from degradation, although oligoubiquitination could still occur, and was efficiently trafficked to the plasma membrane. We propose that targeting to the plasma membrane requires a conformational change in the I-II loop that is induced by binding of the CaVβ subunit.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5034038PMC
http://dx.doi.org/10.1074/jbc.M116.737270DOI Listing
September 2016

New developments in genetics of myositis.

Curr Opin Rheumatol 2016 Nov;28(6):651-6

aCentre for Musculoskeletal Research, University of Manchester, Manchester, UK bCentre for Integrated Genomic Medical Research, University of Manchester, Manchester, UK cCentre for Musculoskeletal Research and National Institute of Health Research, Manchester Musculoskeletal Biomedical Research Unit, Central Manchester University Hospitals NHS Foundation Trust, University of Manchester, Manchester, UK.

Purpose Of Review: This article reviews the advances that have been made in our understanding of the genetics of the idiopathic inflammatory myopathies (IIM) in the past 2 years, with a particular focus on polymyositis, dermatomyositis and inclusion body myositis.

Recent Findings: Two large human leukocyte antigen (HLA) imputation studies have confirmed a strong association with the 8.1 ancestral haplotype in clinical subgroups of myositis and suggest multiple independent associations on this haplotype. Risk in these genes may be due to specific amino acid positions within the peptide-binding grooves of HLA molecules. A large genetic study in 2566 IIM patients revealed associations such as PTPN22, STAT4, UBE2L3 and BLK, which overlap with risk variants reported in other seropositive autoimmune diseases. There is also evidence of different genetic architectures in clinical subgroups of IIM. Candidate gene studies in the Japanese and Chinese populations have replicated previous IIM associations which suggest common aetiology between ethnicities.

Summary: International collaborations have facilitated large genetic studies in IIM that have revealed much about the genetics of this rare complex disease both within the HLA region and genome-wide. Future approaches, such as sequencing and trans-ethnic meta-analyses, will advance our knowledge of IIM genetics.
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http://dx.doi.org/10.1097/BOR.0000000000000328DOI Listing
November 2016

Systematic protein-protein interaction and pathway analyses in the idiopathic inflammatory myopathies.

Arthritis Res Ther 2016 07 7;18(1):156. Epub 2016 Jul 7.

Centre for Epidemiology, University of Manchester, 2.722 Stopford Building, Oxford Road, Manchester, M13 9PT, UK.

Background: The idiopathic inflammatory myopathies (IIM) are autoimmune diseases characterised by acquired proximal muscle weakness, inflammatory cell infiltrates in muscle and myositis-specific/associated autoantibodies. It is unclear which pathways are involved in IIM, and the functional relationship between autoantibody targets has not been systematically explored. Protein-protein interaction and pathway analyses were conducted to identify pathways relevant to disease, using autoantibody targets and gene products of IIM-associated single nucleotide polymorphism (SNP) loci.

Methods: Protein-protein interactions were analysed using Disease Association Protein-Protein Link Evaluator (DAPPLE). Gene ontology and pathway analyses were conducted using Database for Annotation Visualisation and Integrated Discovery (DAVID) and Gene Relationships Across Implicated Loci (GRAIL). Analyses were undertaken including the targets of published autoantibodies, significant and suggestive SNPs from an IIM association study and autoantibody targets plus SNPs combined.

Results: The protein-protein interaction networks formed by autoantibody targets and associated SNPs showed significant direct and/or indirect connectivity (p < 0.05). Autoantibody targets plus associated SNPs combined resulted in more significant indirect and common interactor connectivity, suggesting autoantibody targets and proteins encoded by IIM-associated loci may be involved in common pathways. Tumour necrosis factor receptor-associated factor 6 (TRAF6) was identified as a hub protein, and UBE3B, HSPA1A, HSPA1B and PSMD3 also were identified as genes with significant connectivity. Pathway analysis identified that autoantibody targets and associated SNP regions are significantly interconnected (p < 0.01), and confirmed autoantibody target involvement in translational and post-translational processes. 'Ubiquitin' was the only keyword strongly linking significant genes across regions in all three GRAIL analyses of autoantibody targets and IIM-associated SNPs.

Conclusions: Autoantibody targets and IIM-associated loci show significant connectivity and inter-relatedness, and identify several key genes and pathways in IIM pathogenesis, possibly mediated via the ubiquitination pathway.
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http://dx.doi.org/10.1186/s13075-016-1061-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4936183PMC
July 2016

Dense genotyping of immune-related loci in idiopathic inflammatory myopathies confirms HLA alleles as the strongest genetic risk factor and suggests different genetic background for major clinical subgroups.

Ann Rheum Dis 2016 Aug 11;75(8):1558-66. Epub 2015 Sep 11.

Centre for Integrated Genomic Medical Research, University of Manchester, Manchester, UK.

Objectives: The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of rare autoimmune diseases characterised by muscle weakness and extramuscular manifestations such as skin rashes and interstitial lung disease. We genotyped 2566 IIM cases of Caucasian descent using the Immunochip; a custom array covering 186 established autoimmune susceptibility loci. The cohort was predominantly comprised of patients with dermatomyositis (DM, n=879), juvenile DM (JDM, n=481), polymyositis (PM, n=931) and inclusion body myositis (n=252) collected from 14 countries through the Myositis Genetics Consortium.

Results: The human leucocyte antigen (HLA) and PTPN22 regions reached genome-wide significance (p<5×10(-8)). Nine regions were associated at a significance level of p<2.25×10(-5), including UBE2L3, CD28 and TRAF6, with evidence of independent effects within STAT4. Analysis of clinical subgroups revealed distinct differences between PM, and DM and JDM. PTPN22 was associated at genome-wide significance with PM, but not DM and JDM, suggesting this effect is driven by PM. Additional suggestive associations including IL18R1 and RGS1 in PM and GSDMB in DM were identified. HLA imputation confirmed that alleles HLA-DRB1*03:01 and HLA-B*08:01 of the 8.1 ancestral haplotype (8.1AH) are most strongly associated with IIM, and provides evidence that amino acids within the HLA, such as HLA-DQB1 position 57 in DM, may explain part of the risk in this locus. Associations with alleles outside the 8.1AH reveal differences between PM, DM and JDM.

Conclusions: This work represents the largest IIM genetic study to date, reveals new insights into the genetic architecture of these rare diseases and suggests different predominating pathophysiology in different clinical subgroups.
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http://dx.doi.org/10.1136/annrheumdis-2015-208119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5300750PMC
August 2016

P2X7R activation drives distinct IL-1 responses in dendritic cells compared to macrophages.

Cytokine 2015 Aug 9;74(2):293-304. Epub 2015 Jun 9.

Faculty of Life Sciences, Smith Building, The University of Manchester, UK. Electronic address:

The P2X(7)R is a functionally distinct member of the P2X family of non-selective cation channels associated with rapid activation of the inflammasome complex and signalling interleukin (IL)-1β release in macrophages. The main focus of this investigation was to compare P2X(7)R-driven IL-1 production by primary murine bone marrow derived dendritic cells (BMDC) and macrophages (BMM). P2X(7)R expression in murine BMDC and BMM at both transcriptional (P2X(7)A variant) and protein levels was demonstrated. Priming with lipopolysaccharide (LPS) and receptor activation with adenosine triphosphate (ATP) resulted in markedly enhanced IL-1 (α and β) secretion in BMDC compared with BMM. In both cell types IL-1 production was profoundly inhibited with a P2X(7)R-specific inhibitor (A-740003) demonstrating that this release is predominantly a P2X(7)R-dependent process. These data also suggest that P2X(7)R and caspase-1 activation drive IL-1α release from BMDC. Both cell types expressed constitutively the gain-of-function P2X(7)K as well as the full P2X(7)A variant at equivalent levels. LPS priming reduced significantly levels of P2X(7)A but not P2X(7)K transcripts in both BMDC and BMM. P2X(7)R-induced pore formation, assessed by YO-PRO-1 dye uptake, was greater in BMDC, and these cells were protected from cell death. These data demonstrate that DC and macrophages display distinct patterns of cytokine regulation, particularly with respect to IL-1, as a consequence of cell-type specific differences in the physicochemical properties of the P2X(7)R. Understanding the cell-specific regulation of these cytokines is essential for manipulating such responses in health and disease.
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http://dx.doi.org/10.1016/j.cyto.2015.05.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4504032PMC
August 2015

Strategies for evaluating idiopathic inflammatory myopathy disease susceptibility genes.

Curr Rheumatol Rep 2014 Oct;16(10):446

Centre for Musculoskeletal Research, The University of Manchester, Manchester, UK.

This review outlines the progress that has been made in understanding the genetics of the idiopathic inflammatory myopathies in the previous 2 years, with a particular focus on dermatomyositis and polymyositis. A recent genome-wide association study in dermatomyositis has confirmed the importance of the major histocompatibility region in this disease, and has suggested a shared genetic etiology with other autoimmune disorders. This has led to an ongoing study of additional immune-related loci using the Immunochip array. Candidate gene studies have identified novel risk associations in non-Europeans, such as STAT4 and HLA-DRB1 in the Japanese population. Evidence for gene-environment interactions has come from two recent studies implicating smoking status and statin use with HLA alleles. This review also touches on future approaches to genetic research in myositis, including bioinformatics tools to identify causal variants, HLA imputation from existing genetic data and statistical methods to investigate shared effects between subgroups of myositis.
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http://dx.doi.org/10.1007/s11926-014-0446-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4578230PMC
October 2014

Searching for "monogenic diabetes" in dogs using a candidate gene approach.

Canine Genet Epidemiol 2014 7;1. Epub 2014 Jul 7.

Centre for Integrated Genomic Medical Research, University of Manchester, Stopford Building, Oxford Road, Manchester, M13 9PT UK.

Background: Canine diabetes is a common endocrine disorder with an estimated breed-related prevalence ranging from 0.005% to 1.5% in pet dogs. Increased prevalence in some breeds suggests that diabetes in dogs is influenced by genetic factors and similarities between canine and human diabetes phenotypes suggest that the same genes might be associated with disease susceptibility in both species. Between 1-5% of human diabetes cases result from mutations in a single gene, including maturity onset diabetes of the adult (MODY) and neonatal diabetes mellitus (NDM). It is not clear whether monogenic forms of diabetes exist within some dog breeds. Identification of forms of canine monogenic diabetes could help to resolve the heterogeneity of the condition and lead to development of breed-specific genetic tests for diabetes susceptibility.

Results: Seventeen dog breeds were screened for single nucleotide polymorphisms (SNPs) in eighteen genes that have been associated with human MODY/NDM. Six SNP associations were found from five genes, with one gene (ZFP57) being associated in two different breeds.

Conclusions: Some of the genes that have been associated with susceptibility to MODY and NDM in humans appear to also be associated with canine diabetes, although the limited number of associations identified in this study indicates canine diabetes is a heterogeneous condition and is most likely to be a polygenic trait in most dog breeds.
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http://dx.doi.org/10.1186/2052-6687-1-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4579387PMC
September 2015

Direct gating of ATP-activated ion channels (P2X2 receptors) by lipophilic attachment at the outer end of the second transmembrane domain.

J Biol Chem 2014 Jan 22;289(2):618-26. Epub 2013 Nov 22.

From the Faculty of Life Sciences and.

The ionic pore of the P2X receptor passes through the central axis of six transmembrane (TM) helices, two from each of three subunits. Val(48) and Ile(328) are at the outer end of TM1 and TM2, respectively. Homology models of the open and closed states of P2X2 indicate that pore opening is associated with a large lateral displacement of Ile(328). In addition, molecular dynamics simulations suggest that lipids enter the interstices between the outer ends of the TM domains. The P2X2(I328C) receptor was activated by propyl-methanethiosulfonate (MTS) as effectively as by ATP, but cysteine substitutions elsewhere in TM2 had no such effect. Other lipophilic MTS compounds (methyl, ethyl, and tert-butylethyl) had a similar effect but not polar MTS. The properties of the conducting pathway opened by covalent attachment of propyl-MTS were the same as those opened by ATP, with respect to unitary conductance, rectification, and permeability of N-methyl-d-glucamine. The ATP-binding residue Lys(69) was not required for the action of propyl-MTS, although propyl-MTS did not open P2X2(K308A/I328C) receptors. The propyl-MTS did not open P2X2 receptors in which the Val(48) side chain was removed (P2X2(V48G/I328C)). The results suggest that an interaction between Val(48) and Ile(328) stabilizes the closed channel and that this is broken by covalent attachment of a larger lipophilic moiety at the I328C receptors. Lipid intercalation between the separating TM domains during channel opening would be facilitated in P2X2(I328C) receptors with attached propyl-MTS. The results are consistent with the channel opening mechanism proposed on the basis of closed and open crystal structures and permit the refinement of the position of the TMs within the bilayer.
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http://dx.doi.org/10.1074/jbc.M113.529099DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3887190PMC
January 2014

Entering a new phase of immunogenetics in the idiopathic inflammatory myopathies.

Curr Opin Rheumatol 2013 Nov;25(6):735-41

aCentre for Musculoskeletal Research, Institute of Inflammation and Repair, The University of Manchester, Manchester bMRC/ARUK Institute of Ageing and Chronic Disease, Faculty of Health & Life Sciences, University of Liverpool, Liverpool cCentre for Integrated Genomic Medical Research, The University of Manchester, Manchester, UK.

Purpose Of Review: To review the progress that has been made in understanding the genetics of the idiopathic inflammatory myopathies (IIMs) in the past 2 years, with particular focus on polymyositis, dermatomyositis and inclusion body myositis.

Recent Findings: Candidate gene studies in the Japanese population have implicated signal transducer and activator of transcription 4 as a risk locus for IIM, and HLA-DRB1 as a risk locus for anti-melanoma differentiation-associated gene 5-positive dermatomyositis. Evidence for gene-environment interactions has been found between HLA-DRB1*03 and smoking as a risk factor for the development of anti-histidyl tRNA synthetase antibodies, and HLA-DRB1*11:01 and statins for the development of anti-hydroxymethyl glutaryl-coenzyme A reductase-positive statin-induced myopathy. The HLA-DRB1*03:01/*01:01 genotype confers the highest disease risk in inclusion body myositis. A recent genome-wide association study has been performed in dermatomyositis. The most significant signals were in the major histocompatibility complex region, with other loci suggesting evidence of genetic overlap with different autoimmune diseases.

Summary: Recent association and gene-environment interaction studies have increased our knowledge of genetic risk factors for the IIMs. Ongoing international collaborations will facilitate larger and more meaningful genetic studies revealing much about the genetic architecture of these complex diseases.
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http://dx.doi.org/10.1097/01.bor.0000434676.70268.66DOI Listing
November 2013

A candidate gene analysis of canine hypoadrenocorticism in 3 dog breeds.

J Hered 2013 Nov-Dec;104(6):807-20. Epub 2013 Aug 31.

the Centre for Integrated Genomic Medical Research, The University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, UK.

Canine hypoadrenocorticism is believed to be an immune-related condition. It is rare in the overall dog population but shows a breed-related predisposition with Standard poodles and Portuguese water dogs having a greater prevalence of the condition. It shares many similarities with human primary adrenal insufficiency and is believed to be a naturally occurring, spontaneous model for the human condition. Short haplotype blocks and low levels of linkage disequilibrium in the human genome mean that the identification of genetic contributors to the condition requires large sample numbers. Pedigree dogs have high linkage disequilibrium and long haplotypes within a breed, increasing the potential of identifying novel genes that contribute to canine genetic disease. We investigated 222 SNPs from 42 genes that have been associated or may be implicated in human Addison's disease. We conducted case-control analyses in 3 pedigree dog breeds (Labrador retriever: affected n = 30, unaffected = 76; Cocker Spaniel: affected n = 19, unaffected = 53; Springer spaniel: affected n = 26, unaffected = 46) and identified 8 associated alleles in genes COL4A4, OSBPL9, CTLA4, PTPN22, and STXBP5 in 3 pedigree breeds. Association with immune response genes PTPN22 and CTLA4 in certain breeds suggests an underlying immunopathogenesis of the disease. These results suggest that canine hypoadrenocorticism could be a useful model for studying comparative genetics relevant to human Addison's disease.
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http://dx.doi.org/10.1093/jhered/est051DOI Listing
May 2014

Association of an MHC class II haplotype with increased risk of polymyositis in Hungarian Vizsla dogs.

PLoS One 2013 14;8(2):e56490. Epub 2013 Feb 14.

Centre for Integrated Genomic Medical Research (CIGMR), Institute of Population Health, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, United Kingdom.

A breed-specific polymyositis is frequently observed in the Hungarian Vizsla. Beneficial clinical response to immunosuppressive therapies has been demonstrated which points to an immune-mediated aetiology. Canine inflammatory myopathies share clinical and histological similarities with the human immune-mediated myopathies. As MHC class II associations have been reported in the human conditions we investigated whether an MHC class II association was present in the canine myopathy seen in this breed. 212 Hungarian Vizsla pedigree dogs were stratified both on disease status and degree of relatedness to an affected dog. This generated a group of 29 cases and 183 "graded" controls: 93 unaffected dogs with a first degree affected relative, 44 unaffected dogs with a second degree affected relative, and 46 unaffected dogs with no known affected relatives. Eleven DLA class II haplotypes were identified, of which, DLA-DRB1*02001/DQA1*00401/DQB1*01303, was at significantly raised frequency in cases compared to controls (OR = 1.92, p = 0.032). When only control dogs with no family history of the disease were compared to cases, the association was further strengthened (OR = 4.08, p = 0.00011). Additionally, a single copy of the risk haplotype was sufficient to increase disease risk, with the risk substantially increasing for homozygotes. There was a trend of increasing frequency of this haplotype with degree of relatedness, indicating low disease penetrance. These findings support the hypothesis of an immune-mediated aetiology for this canine myopathy and give credibility to potentially using the Hungarian Vizsla as a genetic model for comparative studies with human myositis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0056490PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3572995PMC
August 2013