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- Demirdal, D, et al.
(författare)
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CHARACTERISATION OF SWEDISH MYOSITIS PATIENTS WITH ANTI-MDA5 AUTOANTIBODIES AND CORRELATION OF CLINICAL FEATURES WITH AUTOANTIBODY LEVELS
- 2022
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Ingår i: ANNALS OF THE RHEUMATIC DISEASES. - : BMJ. - 0003-4967 .- 1468-2060. ; 81, s. 751-752
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The association between anti-melanoma differentiation association protein 5 autoantibodies (aMDA5) and rapidly progressive interstitial lung disease (RP-ILD) in clinically amyopathic dermatomyositis is well established in Asian population cohorts. In western cohorts, ILD has been strongly associated with aMDA5 but data regarding RP-ILD have been more conflicting. It is also suggested that western cohorts have more pronounced myopathic features than Asian.ObjectivesTo characterise the disease manifestations of a Swedish aMDA5 positive idiopathic inflammatory myositis (IIM) cohort and to explore antigen reactivity of the MDA5 protein.MethodsFirst available serum samples collected from 28 consecutive patients with IIM and positive aMDA5 ever tested by ELISA, Line Blot (LB) or Immunoprecipitation, attending Karolinska University Hospital between 1999 and 2021, were included. Clinical data including presence of anti-SSA autoantibodies by ELISA or LB was retrieved retrospectively. An in-house ELISA was used to screen serum samples for reactivity against a recombinant MDA5 protein (rMDA5, aa A110-D1025, UniProt ID Q9BYX4) and seven MDA5-derived constructs containing different domains. Correlations between aMDA5 reactivity levels and clinical data were explored.ResultsNine patients showed no reactivity to any of the rMDA5 constructs by ELISA and were excluded from further analysis.Reactivity against rMDA5 was confirmed by ELISA in 19 patients (median 184.7 µg/mL (interquartile range (IQR) 277.07). The cohort included 13 male and 6 female patients, 94% Caucasian, with mean age at diagnosis of 41.05 years (standard deviation (SD) 10.5). Median disease duration at time of sampling was 0 months (IQR 1). All patients except one had signs of muscle involvement (muscle weakness, elevated muscle enzymes, muscle oedema or muscle biopsy consistent with myositis). At diagnosis 63.2% of patients reported muscle weakness (21.1 % had a manual muscle test 8 score <75). Dermatological findings were observed in 17/19 (89.7 %). During disease course nine patients (47.4%) had confirmed arthritis.ILD was diagnosed in 16/19 patients (84.2%), four of these (25%) developed a RP-ILD. One patient passed away due to RP-ILD and one required a lung transplant. Patients with ILD had a statistically significant higher mean age at diagnosis than those without (42.8.5 (SD 10.3) vs 31.3 (SD 4.7) years, p=0.02). Patients developing RP-ILD were not significantly older than patients with chronic ILD. Respiratory symptoms were reported by 75% of patients with ILD at time of diagnosis. The mean total lung capacity (TLC) of the ILD cohort was 68% (SD 17), mean diffusion capacity of carbon monoxide (DLCO) was 59% (SD 15) and mean forced vital capacity (FVC) was 62% (SD 19). There was a higher proportion of patients with CRP ≥ 3 times the reference range at diagnosis amongst patients with FVC <70 % than patients with FVC >70 % (88.9 % vs 16.7 %, p= 0.01).Ten patients (52.6%) had anti-SSA autoantibodies, all had ILD. Anti-SSA positive patients had a statistically significant lower TLC than those without (62% vs 79% respectively, p=0.04) and a lower FVC (57% vs 76% respectively, p=0.05).We found a weak non-statistically significant negative correlation between titres of aMDA5 and TLC, DLCO and FVC (Pearson coefficients -0.187, -0.289, -0.130 respectively). Frequency of ILD was higher in patients with aMDA5 titres >100 µg/mL than those with titers <100, but not statistically significant (81.3% vs 18.8%, respectively).ConclusionIn this Caucasian cohort of aMDA5 positive IIM patients, ILD was present in over 80% of patients, of these, one quarter had RP-ILD. Older patients were more likely to present with ILD. Anti-SSA positivity and higher CRP levels were associated with worse lung function. We found a weak negative correlation between aMDA5 titres and lung function tests, as well as a trend of higher frequency of ILD in patients with higher aMDA5 titres. Muscle and skin involvement were found in a high proportion of patients.AcknowledgementsD. Demirdal & E. Van Gompel contributed equally to this abstract.Disclosure of InterestsDeniz Demirdal: None declared, Eveline Van Gompel: None declared, Edvard Wigren: None declared, Maryam Dastmalchi: None declared, Begum Horuluoglu: None declared, Angeles Shunashy Galindo-Feria: None declared, Susanne Gräslund: None declared, Karine Chemin: None declared, Ingrid E. Lundberg Shareholder of: Roche and Novartis., Consultant of: Consulting fees from Corbus Pharmaceuticals Inc, Astra Zeneca, Bristol Myer´s Squibb, Corbus Pharmaceutical, EMD Serono Research & Development Institute, Argenx, Octapharma, Kezaar, Orphazyme, and Janssen, Grant/research support from: Research grants from Astra Zeneca, Antonella Notarnicola Speakers bureau: compensation for lecture at conference sponsored by Boehringer Ingelheim.
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- Preger, C., et al.
(författare)
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Characterization of anti-aminoacyl TRNA synthetase autoantibodies in patients with idiopathic inflammatory myopathies
- 2020
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ Publishing Group. - 0003-4967 .- 1468-2060. ; 79, s. 1084-1085
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Idiopathic inflammatory myopathies (IIM) are rare chronic inflammatory diseases associated with high mortality and morbidity [1]. One sub-group of IIM, anti-synthetase syndrome (ASS), is characterized by the presence of autoantibodies that target aminoacyl transfer(t) RNA synthetases (aaRS), together with specific clinical manifestations such as myositis, interstitial lung disease (ILD), arthritis, mechanic’s hand, Raynaud’s syndrome and fever [2]. The most common anti-aaRS autoantibody, anti-Jo1 targeting histidyl tRNA synthetase (HisRS), is present in up to 20-30% of patients with IIM, and up to 90% of patients with myositis and ILD [3, 4]. Besides Jo1, there are today seven other identified autoantigens within the aaRS family.Objectives:A large part of patients with IIM, including individuals with clinical manifestations indicating ASS, test seronegative to all known myositis specific autoantibodies. However, these patients could potentially harbor autoantibodies against targets not tested for in clinic. In this study, we aimed at extending the detection of autoantibodies by including all cytoplasmic aaRS in the analysis of patients with IIM. We hypothesized the existence of new potential autoantigens within this protein family.Methods:The presence of anti-aaRS autoantibodies was determined using a multiplex suspension bead array assay on 242 IIM patients from the Karolinska University Hospital myositis cohort. A panel of 186 recombinant constructs, representing 57 proteins that included full-length or partial sequence overlaps between constructs of all cytoplasmic aaRS as well as other myositis related proteins, were coupled to magnetic color-coded beads and each plasma sample was tested against the complete antigen panel.Results:By the use of this multiplex method we identified patients with autoantibodies against many of the tested aaRS. Autoantibodies binding to HisRS have previously been shown to bind with higher reactivity to the WHEP domain of HisRS and this was also confirmed in this study. We confirmed reactivity against three of the other aaRS tested for in the clinic (PL-12, PL-7, and EJ). In addition, we identified patients positive for anti-Zo, -KS and -HA, autoantibodies usually not screened for in routine. Finally, our data indicates that there are autoantibodies binding to other aaRS than the previously known eight autoantigens, which will be presented.Conclusion:In this study, we could detect autoantibodies in plasma from patients with IIM, both against the most common aaRS autoantigens, but also against other aaRS that are usually not tested for in clinic. We conclude that it is important to continue the studies of anti-aaRS autoantibodies, and their correlation to clinical manifestations, and in the long run also include more aaRS autoantigens in clinical practice.References:[1]Dobloug, G.C., et al., Mortality in idiopathic inflammatory myopathy: results from a Swedish nationwide population-based cohort study. Ann Rheum Dis, 2018. 77(1): p. 40-47.[2]Barsotti, S. and I.E. Lundberg, Myositis an evolving spectrum of disease. Immunol Med, 2018. 41(2): p. 46-54.[3]Vencovsky, J., H. Alexanderson, and I.E. Lundberg, Idiopathic Inflammatory Myopathies. Rheum Dis Clin North Am, 2019. 45(4): p. 569-581.[4]Richards, T.J., et al., Characterization and peripheral blood biomarker assessment of anti-Jo-1 antibody-positive interstitial lung disease. Arthritis Rheum, 2009. 60(7): p. 2183-92.Disclosure of Interests:Charlotta Preger: None declared, Antonella Notarnicola: None declared, Cecilia Hellström: None declared, Edvard Wigren: None declared, Catia Cerqueira: None declared, Peter Nilsson: None declared, Ingrid E. Lundberg Grant/research support from: Bristol Meyer Squibb, Corbus Pharmaceuticals, Inc and Astra Zeneca, Helena Persson: None declared, Susanne Gräslund: None declared, Per-Johan Jakobsson Shareholder of: Gesynta Pharma, Grant/research support from: Gesynta Pharma, AstraZeneca,
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- Rajkovic, Andrei, et al.
(författare)
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Amino acid substitutions in human growth hormone affect secondary structure and receptor binding
- 2023
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 18:3
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Tidskriftsartikel (refereegranskat)abstract
- The interaction between human Growth Hormone (hGH) and hGH Receptor (hGHR) has basic relevance to cancer and growth disorders, and hGH is the scaffold for Pegvisomant, an anti-acromegaly therapeutic. For the latter reason, hGH has been extensively engineered by early workers to improve binding and other properties. We are particularly interested in E174 which belongs to the hGH zinc-binding triad; the substitution E174A is known to significantly increase binding, but to now no explanation has been offered. We generated this and several computationally-selected single-residue substitutions at the hGHR-binding site of hGH. We find that, while many successfully slow down dissociation of the hGH-hGHR complex once bound, they also slow down the association of hGH to hGHR. The E174A substitution induces a change in the Circular Dichroism spectrum that suggests the appearance of coiled-coiling. Here we show that E174A increases affinity of hGH against hGHR because the off-rate is slowed down more than the on-rate. For E174Y (and certain mutations at other sites) the slowdown in on-rate was greater than that of the off-rate, leading to decreased affinity. The results point to a link between structure, zinc binding, and hGHR-binding affinity in hGH.
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