Predicting the development of rheumatoid arthritis (RA) in an early stage through magnetic resonance imaging (MRI) can initiate timely treatment and improve long-term patient outcomes. Although... Show morePredicting the development of rheumatoid arthritis (RA) in an early stage through magnetic resonance imaging (MRI) can initiate timely treatment and improve long-term patient outcomes. Although manual prediction is time-consuming and requires expert knowledge, automatic RA prediction has not been fully investigated. While standard models fail to achieve acceptable performance, we present a consistency-based deep learning framework to classify and predict RA automatically and precisely, including an output-standardized model, customized self-supervised pretraining and a loss function that is based on label consistency between original and augmented inputs. For training and evaluation, we used a database, containing 5945 MRI scans of carpal, metacarpophalangeal (MCP), and metatarsophalangeal (MTP) joints, from 2151 subjects obtained over a period of ten years. Four (three classification- and one prediction-) tasks were defined to distinguish two patient groups (with recent-onset arthritis and clinically suspect arthralgia) from healthy controls and RA from other arthritis patients within the recent-onset arthritis group, and predict RA development in a period of two years within the clinically suspect arthralgia group. The proposed method was evaluated with the area under the receiver operating curve (AUROC) on a separate test set, achieving mean AUROCs of 83.6%, 83.3%, and 69.7% in the three classification tasks, and 67.8% in the prediction task. This proves the existence of early signs of RA in MRI and the potential of a consistency-based deep learning model to detect these early signs and predict RA Show less
Hassanzadeh, T.; Shamonin, D.P.; Li, Y.L.; Krijbolder, D.I.; Reijnierse, M.; Helm-van Mil, A.H.M.V. van der; Stoel, B.C. 2024
Rheumatoid Arthritis (RA) is an autoimmune disease that mainly affects joints in the wrist and hands. It typically results in inflamed and painful joints. MRI is one of the most common imaging...Show moreRheumatoid Arthritis (RA) is an autoimmune disease that mainly affects joints in the wrist and hands. It typically results in inflamed and painful joints. MRI is one of the most common imaging modalities to detect and monitor possible inflamed RA-related areas, enabling rheumatologists to treat patients more timely and efficiently. Despite the importance of finding and tracking inflamed areas associated with RA in MRI, there is no previously published work on finding pixel-by-pixel changes related to RA between baseline and follow-up MRIs. Therefore, this paper proposes a hypothesis-free deep learning-based model to discover changes in wrist MRIs on a pixel level to detect changes in inflamed areas related to RA without using prior anatomical information. To do this, a combination of a U-Net-based network and image thresholding was utilised to find pixel-level non-trivial changes between baseline and follow-up MRI images. A wrist MRI dataset including 99 individual pairs of MRI images (each pair constructed of baseline and follow-up images) was used to evaluate the proposed model. Data were collected from patients with clinically suspected arthralgia (CSA), defined as patients at risk of developing RA according to their rheumatologist and already had subclinical inflammation on MRI but could not be diagnosed with RA (yet) since they had not developed clinically detectable arthritis. The obtained results were evaluated using an observer study. The evaluation showed that our proposed model is a promising first step toward developing an automatic model to find RA-related inflammatory changes. Show less
The aim of the studies described in this thesis is to come to better understanding of the anti-modified protein antibody (AMPA) response in rheumatoid arthritis (RA) and to investigate the origin... Show moreThe aim of the studies described in this thesis is to come to better understanding of the anti-modified protein antibody (AMPA) response in rheumatoid arthritis (RA) and to investigate the origin of this response at both the antibody and B cell level. This is relevant as such studies could give insights on how B cell tolerance in RA is breached and gives rise to autoreactive B cells and the production of autoantibodies. This knowledge is important for preventing the disease or defining potential targets to treat the disease. Show less
Wissen, M.A.T. van; Berger, M.A.M.; Schoones, J.W.; Gademan, M.G.J.; Ende, C.H.M. van den; Vlieland, T.P.M.V.; Weely, S.F.E. van 2022
To assess the reporting quality of interventions aiming at promoting physical activity (PA) using a wearable activity tracker (WAT) in patients with inflammatory arthritis (IA) or hip/knee... Show moreTo assess the reporting quality of interventions aiming at promoting physical activity (PA) using a wearable activity tracker (WAT) in patients with inflammatory arthritis (IA) or hip/knee osteoarthritis (OA). A systematic search was performed in eight databases (including PubMed, Embase and Cochrane Library) for studies published between 2000 and 2022. Two reviewers independently selected studies and extracted data on study characteristics and the reporting of the PA intervention using a WAT using the Consensus on Exercise Reporting Template (CERT) (12 items) and Consolidated Standards of Reporting Trials (CONSORT) E-Health checklist (16 items). The reporting quality of each study was expressed as a percentage of reported items of the total CERT and CONSORT E-Health (50% or less = poor; 51-79% = moderate; and 80-100% = good reporting quality). Sixteen studies were included; three involved patients with IA and 13 with OA. Reporting quality was poor in 6/16 studies and moderate in 10/16 studies, according to the CERT and poor in 8/16 and moderate in 8/16 studies following the CONSORT E-Health checklist. Poorly reported checklist items included: the description of decision rule(s) for determining progression and the starting level, the number of adverse events and how adherence or fidelity was assessed. In clinical trials on PA interventions using a WAT in patients with IA or OA, the reporting quality of delivery process is moderate to poor. The poor reporting quality of the progression and tailoring of the PA programs makes replication difficult. Improvements in reporting quality are necessary. Show less
The studies described in this thesis provides the field with valuable data on the potential therapeutic effects of fatty acids and specialized pro-resolving lipid mediators in rheumatoid arthritis... Show moreThe studies described in this thesis provides the field with valuable data on the potential therapeutic effects of fatty acids and specialized pro-resolving lipid mediators in rheumatoid arthritis and osteoarthritis. The omega-6 fatty acid AdA shows potent pro-resolving effects on the production of pro-inflammatory chemoattractantLTB4 with great promise to limit RA disease progression. In contrast to the promising potential therapeutic effects of AdA in RA, the evidence for pro-resolving effects in OA is still scarce. The results of the studies from this thesis show that neither LXA4, LXB4, RvE2 or Mar-1 were able to reduce OA disease activity in the experimental set-up we used. Finally, the studies described in this thesis show the utmost critical importance of the right sample preparation and storage for the intended subsequent analysis. Show less
ackgroundRheumatoid arthritis (RA) is a chronic autoimmune disease for which prediction of long-term prognosis from disease’s outset is not clinically feasible. The importance of immunoglobulin G ... Show moreackgroundRheumatoid arthritis (RA) is a chronic autoimmune disease for which prediction of long-term prognosis from disease’s outset is not clinically feasible. The importance of immunoglobulin G (IgG) and its Fc N-glycosylation in inflammation is well-known and studies described its relevance for several autoimmune diseases, including RA. Herein we assessed the association between IgG N-glycoforms and disease prognosis at 2 years in an early inflammatory arthritis cohort.MethodsSera from 118 patients with early inflammatory arthritis naïve to treatment sampled at baseline were used to obtain IgG Fc glycopeptides, which were then analyzed in a subclass-specific manner by liquid chromatography coupled to mass spectrometry (LC-MS). Patients were prospectively followed and a favorable prognosis at 2 years was assessed by a combined index as remission or low disease activity (DAS28 < 3.2) and normal functionality (HAQ ≤ 0.25) while on treatment with conventional synthetic DMARDs and never used biologic DMARDs.ResultsWe observed a significant association between high levels of IgG2/3 Fc galactosylation (effect 0.627 and adjusted p value 0.036 for the fully galactosylated glycoform H5N4F1; effect −0.551 and adjusted p value 0.04963 for the agalactosylated H3N4F1) and favorable outcome after 2 years of treatment. The inclusion of IgG glycoprofiling in a multivariate analysis to predict the outcome (with HAQ, DAS28, RF, and ACPA included in the model) did not improve the prognostic performance of the model.ConclusionPending confirmation of these findings in larger cohorts, IgG glycosylation levels could be used as a prognostic marker in early arthritis, to overcome the limitations of the current prognostic tools. Show less
Dakkak, Y.J.; Dijk, B.T. van; Jansen, F.P.; Wisse, L.J.; Reijnierse, M.; Helm-van Mil, A.H.M. van der; DeRuiter, M.C. 2022
MRI-detected inflammation around the extensor tendons of metacarpophalangeal (MCP-) joints is prevalent in RA and poses a markedly increased risk of RA development when present in arthralgia... Show moreMRI-detected inflammation around the extensor tendons of metacarpophalangeal (MCP-) joints is prevalent in RA and poses a markedly increased risk of RA development when present in arthralgia patients. Such inflammation is called 'peritendinitis' since anatomy literature reports no presence of a tenosynovial sheath at these tendons. However, the presence or absence of tenosynovium at these extensor tendons has never been studied. Therefore, an anatomical and histological study of extensor tendons at the MCP-joints of three embalmed human hands was performed. Immunohistochemical staining showed the presence of markers for synovial macrophages and fibroblast-like synoviocytes bordering a natural dorsal space next to the extensor tendon, suggesting the presence of a synovial lining. This implies that contrast-enhancement on MRI around extensor tendons at MCP-joints observed in early RA and pre-RA likely represents tenosynovitis and that inflammation of this synovial tissue is an early feature of RA. Show less
Anti-citrullinated protein antibodies (ACPA) are highly specific biomarkers for rheumatoid arthritis (RA). ACPA are predominantly of the immunoglobulin (Ig)G isotype and 90% of ACPA-IgG contains N... Show moreAnti-citrullinated protein antibodies (ACPA) are highly specific biomarkers for rheumatoid arthritis (RA). ACPA are predominantly of the immunoglobulin (Ig)G isotype and 90% of ACPA-IgG contains N-glycans in the variable domain. With the research in this thesis, we showed that this remarkably high frequency of N-glycans on secreted ACPA-IgG corresponds to a high frequency of N-glycosylation sites in full-length variable region B-cell receptor (BCR) transcripts of ACPA-expressing B cells. We looked at clonotypes and mutational analysis of the BCR sequences and studied the frequency, position and introduction of N-glycosylation sites that distinguish ACPA-expressing B cells in RA from other (antigen-specific) B-cells. Show less
This thesis aims to assess the differences and similarities between autoantibody-positive and autoantibody-negative RA from the start of complaints to the end of the disease. The described research... Show moreThis thesis aims to assess the differences and similarities between autoantibody-positive and autoantibody-negative RA from the start of complaints to the end of the disease. The described research was performed with the ultimate goal to clarify whether autoantibody-negative and autoantibody-positive RA are distinct diseases that require different diagnoses and treatment. Show less
Rheumatoid arthritis (RA) is a chronic, symmetrical, autoimmune disease characterized by inflammation of the joints, as well as damage to a variety of body systems, including the skin, eyes, lungs,... Show moreRheumatoid arthritis (RA) is a chronic, symmetrical, autoimmune disease characterized by inflammation of the joints, as well as damage to a variety of body systems, including the skin, eyes, lungs, heart and blood vessels. Therefore, to prevent (potential) damage with a more favorable course of the disease, it is important to intervene both early and agressively with medication in the treatment of RA. Typically, methotrexate is used as the first treatment, possibly in conjuction with other disease-modifying antirheumatic drugs, or with prednisolone to reduce inflammation rapidly. While the treatment of RA has improved considerably in recent decades, drug treatment does not work for everyone due to toxicity or lack of responsiveness. Therefore, it is suspected that genetics plays a major role in the both efficacy and toxicity of current RA medication. The goal of this thesis is to identify the genetic factors that influence the effectiveness or toxicity of the drugs used in RA. Show less
Background: Drug-free remission is a desirable goal in rheumatoid arthritis (RA) for both patients and clinicians. The aim of this post hoc analysis was to investigate whether clinical and magnetic... Show moreBackground: Drug-free remission is a desirable goal in rheumatoid arthritis (RA) for both patients and clinicians. The aim of this post hoc analysis was to investigate whether clinical and magnetic resonance imaging (MRI) variables in patients with early RA who achieved remission with methotrexate and/or abatacept at 12 months could predict disease flare following treatment withdrawal.Methods: In the AVERT study of abatacept in early RA, patients with low disease activity at month 12 entered a 12-month period with all treatment discontinued (withdrawal, WD). This post hoc analysis assessed predictors of disease flare at WD+6months (mo) and WD+12mo of patients with Disease Activity Score in 28 joints (DAS28)-defined remission (DAS28[C-reactive protein (CRP)] <2.6) at withdrawal using univariate and multivariable regression models. Predictors investigated included the Health Assessment Questionnaire-Disability Index (HAQ-DI), pain, Patient Global Assessment; MRI synovitis, erosion, bone edema, and combined (synovitis + bone edema) inflammation scores.Results: Remission was achieved by 172 patients; 100 (58%) and 113 (66%) patients had experienced a flare at WD+6mo and WD+12mo, respectively. In univariate analyses, higher HAQ-DI and MRI synovitis, erosion, bone edema, and combined inflammation scores at WD were identified as potential predictors of flare (P < 0.01). In multivariable analysis, high scores at WD for HAQ-DI and MRI erosion were confirmed as independent predictors of flare at WD+6mo and WD+12mo (P < 0.01).Conclusion: In patients with early RA achieving clinical remission, patient function (HAQ-DI), and MRI measures of bone damage (erosion) predicted disease flare 6 and 12 months after treatment withdrawal. These variables may help identify patients with early RA in clinical remission as candidates for successful treatment withdrawal. Show less
Hasan, A. al; Reimann, F.; Veeger, N.J.G.M.; Bergstra, S.A.; Zhang, D.; Bourgonje, A.R.; ... ; Bos, R. 2022
The Handscan is a novel objective optical imaging device for disease follow-up and management in rheumatoid arthritis patients. We aim to examine the association between the baseline outcomes of... Show moreThe Handscan is a novel objective optical imaging device for disease follow-up and management in rheumatoid arthritis patients. We aim to examine the association between the baseline outcomes of the Handscan, disease activity levels and joint swelling. The Handscan measures differences in laser light absorption between joints of fingers and wrists and adjacent reference tissue, indicating the presence or absence of inflammation. The device gives an optical spectral transmission (OST) index per joint. The average of these indices is represented in the total optical score (TOS). Associations between TOS and DAS28 at subject level and OST and swelling at joint level were examined. 484 RA patients were included. Compared to patients with high disease activity (defined by DAS28), TOS was significantly lower in patients with moderate (estimated coefficient B: - 7.09, P < 0.001), low disease activity (B: - 6.99, P < 0.001) and patients in remission (B: - 7.72, P < 0.001) but could not distinguish between the latter three disease states. TOS was significantly lower in females (B: - 3.2, P < 0.001). OST was significantly higher in swollen than non-swollen joints (B: 0.28, P < 0.001). TOS was significantly higher in patients with high disease activity than in those in remission or with low and moderate disease activity. The difference in TOS between males and females should be accounted for in the interpretation of this outcome. The OST at joint level discriminates swollen from non-swollen joints and could be a more promising tool than the overall optical activity reflected in TOS. Show less
Brouwers, H.; Hegedus, J.H. von; Linden, E. van der; Mahdad, R.; Kloppenburg, M.; Toes, R.; ... ; Ioan-Facsinay, A. 2022
Background Synovial fluid (SF) is commonly used for diagnostic and research purposes, as it is believed to reflect the local inflammatory environment. Owing to its complex composition and... Show moreBackground Synovial fluid (SF) is commonly used for diagnostic and research purposes, as it is believed to reflect the local inflammatory environment. Owing to its complex composition and especially the presence of hyaluronic acid, SF is usually viscous and non-homogeneous. In this study, we investigated the importance of homogenization of the total SF sample before subsequent analysis. Methods SF was obtained from the knee of 29 arthritis patients (26 rheumatoid arthritis, 2 osteoarthritis, and 1 juvenile idiopathic arthritis patient) as part of standard clinical care. Synovial fluid was either treated with hyaluronidase as a whole or after aliquoting to determine whether the concentration of soluble mediators is evenly distributed in the viscous synovial fluid. Cytokine and IgG levels were measured by ELISA or Luminex and a total of seven fatty acid and oxylipin levels were determined using LC-MS/MS in all aliquots. For cell analysis, synovial fluid was first centrifuged and the pellet was separated from the fluid. The fluid was subsequently treated with hyaluronidase and centrifuged to isolate remaining cells. Cell numbers and phenotype were determined using flow cytometry. Results In all patients, there was less variation in IgG, 17-HDHA, leukotriene B-4 (LTB4), and prostaglandin E-2 (PGE(2)) levels when homogenization was performed before aliquoting the SF sample. There was no difference in variation for cytokines, 15-HETE, and fatty acids arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Between 0.8 and 70% of immune cells (median 5%) remained in suspension and were missing in subsequent analyses when the cells were isolated from untreated SF. This percentage was higher for T and B cells: 7-85% (median 22%) and 7-88% (median 23 %), respectively. Conclusions Homogenization of the entire SF sample leads to less variability in IgG and oxylipin levels and prevents erroneous conclusions based on incomplete isolation of synovial fluid cells. Show less
Objective: Inflammatory hand arthritis (IHA) results in impaired function. Local gene therapy with ART-I02, a recombinant adeno-associated virus (AAV) serotype 5 vector expressing interferon (IFN)... Show moreObjective: Inflammatory hand arthritis (IHA) results in impaired function. Local gene therapy with ART-I02, a recombinant adeno-associated virus (AAV) serotype 5 vector expressing interferon (IFN)-beta, under the transcriptional control of nuclear factor kappa-B responsive promoter, was preclinically shown to have favorable effects. This study aimed to investigate the safety and tolerability of local gene therapy with ART-I02 in patients with IHA.Methods: In this first-in-human, dose-escalating, cohort study, 12 IHA patients were to receive a single intra-articular (IA) injection of ART-I02 ranging 0.3 x 10(12)-1.2 x 10(13) genome copies in an affected hand joint. Adverse events (AEs), routine safety laboratory and the clinical course of disease were periodically evaluated. Baseline- and follow-up contrast enhanced magnetic resonance images (MRIs), shedding of viral vectors in bodily fluids, and AAV5 and IFN-beta immune responses were evaluated. A data review committee provided safety recommendations.Results: Four patients were enrolled. Long-lasting local AEs were observed in 3 patients upon IA injection of ART-I02. The AEs were moderate in severity and could be treated conservative. Given the duration of the AEs and their possible or probable relation to ART-I02, no additional patients were enrolled. No systemic treatment emergent AEs were observed. The MRIs reflected the AEs by (peri)arthritis. No T-cell response against AAV5 or IFN-beta, nor IFN-beta antibodies could be detected. Neutralizing antibody titers against AAV5 raised post-dose.Conclusion: Single IA doses of 0.6 x 10(12) or 1.2 x 10(12) ART-I02 vector genomes were administered without systemic side effects or serious AEs. However, local tolerability was insufficient for continuation. (C) 2021 Published by Elsevier Ltd on behalf of Osteoarthritis Research Society International. Show less
ObjectiveInflammatory hand arthritis (IHA) results in impaired function. Local gene therapy with ART-I02, a recombinant adeno-associated virus (AAV) serotype 5 vector expressing interferon (IFN)-β,... Show moreObjectiveInflammatory hand arthritis (IHA) results in impaired function. Local gene therapy with ART-I02, a recombinant adeno-associated virus (AAV) serotype 5 vector expressing interferon (IFN)-β, under the transcriptional control of nuclear factor κ-B responsive promoter, was preclinically shown to have favorable effects. This study aimed to investigate the safety and tolerability of local gene therapy with ART-I02 in patients with IHA.MethodsIn this first-in-human, dose-escalating, cohort study, 12 IHA patients were to receive a single intra-articular (IA) injection of ART-I02 ranging 0.3 × 1012-1.2 × 1013 genome copies in an affected hand joint. Adverse events (AEs), routine safety laboratory and the clinical course of disease were periodically evaluated. Baseline- and follow-up contrast enhanced magnetic resonance images (MRIs), shedding of viral vectors in bodily fluids, and AAV5 and IFN-β immune responses were evaluated. A data review committee provided safety recommendations.ResultsFour patients were enrolled. Long-lasting local AEs were observed in 3 patients upon IA injection of ART-I02. The AEs were moderate in severity and could be treated conservative. Given the duration of the AEs and their possible or probable relation to ART-I02, no additional patients were enrolled. No systemic treatment emergent AEs were observed. The MRIs reflected the AEs by (peri)arthritis. No T-cell response against AAV5 or IFN-β, nor IFN-β antibodies could be detected. Neutralizing antibody titers against AAV5 raised post-dose.ConclusionSingle IA doses of 0.6 × 1012 or 1.2 × 1012 ART-I02 vector genomes were administered without systemic side effects or serious AEs. However, local tolerability was insufficient for continuation. Show less
In order to be able to develop effective medicine and treatments to prevent or cure autoimmune diseases or cancer we need to understand the mechanisms how they arise and what drives their course... Show moreIn order to be able to develop effective medicine and treatments to prevent or cure autoimmune diseases or cancer we need to understand the mechanisms how they arise and what drives their course.Unravelling the fundamental molecular mechanisms influencing the onset and course of diseases such as allergies, rheumatoid arthritis or cancer can be tackled using bioorthogonal antigens – chemically functionalized proteins.To tackle this challenge this thesis uses an inter-disciplinary approach. Combining standard immunological experimental methods with special, highly selective bioorthogonal chemical reactions. These reactions are bioorthogonal because, unlike normal organic chemistry, they are compatible with the physiological environment of a cell. This approach allows for following for example the location of the protein over time within a cell or alterations in the immune response due to disease related changes to the protein without disturbing the processes themself.This is a significant advantage because without changing the method used, new information can be retrieved from the same set of experiments, at any point in time during the process and a plethora of new readout options yielding additional data sets.This promises new insights into the causal relation of time, localisation and factors influencing effective anti-cancer vaccine-design and cancer immunotherapy or new biological drugs to prevent or delay onset and progression of autoimmune diseases. Show less
Koppejan, H.; Hameetman, M.; Beyrend, G.; Unen, V. van; Kwekkeboom, J.C.; Helm-van Mil, A.H. van der; ... ; Gaalen, F.A. van 2021
Background Autoantibody production is a hallmark of rheumatoid arthritis (RA). Anti-citrullinated protein antibodies (ACPA) are highly disease-specific, and their presence is associated with more... Show moreBackground Autoantibody production is a hallmark of rheumatoid arthritis (RA). Anti-citrullinated protein antibodies (ACPA) are highly disease-specific, and their presence is associated with more severe disease and poor prognosis compared to ACPA-negative patients. However, the immune cell composition associated with antibody-positive/negative disease is incompletely defined. Mass cytometry (MC) is a high-dimensional technique offering new possibilities in the determination of the immune cell composition in rheumatic diseases. Here, we set up a broad phenotyping panel to study the immune cell profile of early untreated RA to investigate if specific immune cell subsets are associated with ACPA+ versus ACPA- RA. Methods Freshly obtained PBMCs of early, untreated RA patients (8 ACPA+ and 7 ACPA-) were analysed using a 36-marker MC panel, including markers related to various immune lineages. Data were processed using Cytosplore for dimensional reduction (HSNE) and clustering. Groups were compared using Cytofast. A second validation cohort of cryopreserved PBMCs obtained from early RA patients (27 ACPA+ and 20 ACPA-) was used to confirm MC data by flow cytometry (FC). FC data were processed and analysed using both an unsupervised analysis pipeline and through manual gating. Results MC indicated no differences when comparing major immune lineages (i.e. monocytes, T and B cells), but highlighted two innate subsets: CD62L(+) basophils (p = 0.33) and a subset of CD16(-) NK cells (p = 0.063). Although the NK cell subset did not replicate by FC, FC replication confirmed the difference in CD62L(+) basophil frequency when comparing ACPA+ to ACPA- patients (mean 0.32% vs. 0.13%; p = 0.01). Conclusions Although no differences in major lineages were found between early ACPA+ and ACPA- RA, this study identified the reduced presence of activated basophils in ACPA-negative disease as compared to ACPA-positive disease and thereby provides the first evidence for a connection between activated basophils and ACPA status. Show less
Background Anti-modified protein antibodies (AMPA) targeting citrullinated, acetylated and/or carbamylated self-antigens are hallmarks of rheumatoid arthritis (RA). Although AMPA-IgG cross... Show moreBackground Anti-modified protein antibodies (AMPA) targeting citrullinated, acetylated and/or carbamylated self-antigens are hallmarks of rheumatoid arthritis (RA). Although AMPA-IgG cross-reactivity to multiple post-translational modifications (PTMs) is evident, it is unknown whether the first responding B cells, expressing IgM, display similar characteristics or if cross-reactivity is crucially dependent on somatic hypermutation (SHM). We now studied the reactivity of (germline) AMPA-IgM to further understand the breach of B cell tolerance and to identify if cross-reactivity depends on extensive SHM. Moreover, we investigated whether AMPA-IgM can efficiently recruit immune effector mechanisms. Methods Polyclonal AMPA-IgM were isolated from RA patients and assessed for cross-reactivity towards PTM antigens. AMPA-IgM B cell receptor sequences were obtained by single cell isolation using antigen-specific tetramers. Subsequently, pentameric monoclonal AMPA-IgM, their germline counterparts and monomeric IgG variants were generated. The antibodies were analysed on a panel of PTM antigens and tested for complement activation. Results Pentameric monoclonal and polyclonal AMPA-IgM displayed cross-reactivity to multiple antigens and different PTMs. PTM antigen recognition was still present, although reduced, after reverting the IgM into germline. Valency of AMPA-IgM was crucial for antigen recognition as PTM-reactivity significantly decreased when AMPA-IgM were expressed as IgG. Furthermore, AMPA-IgM was 15- to 30-fold more potent in complement-activation compared to AMPA-IgG. Conclusions We provide first evidence that AMPA-IgM are cross-reactive towards different PTMs, indicating that PTM (cross-)reactivity is not confined to IgG and does not necessarily depend on extensive somatic hypermutation. Moreover, our data indicate that a diverse set of PTM antigens could be involved in the initial tolerance breach in RA and suggest that AMPA-IgM can induce complement-activation and thereby inflammation. Show less
Maarseveen, T.D.; Maurits, M.P.; Niemantsverdriet, E.; Helm-van Mil, A.H.M. van der; Huizinga, T.W.J.; Knevel, R. 2021
Background Electronic health records (EHRs) offer a wealth of observational data. Machine-learning (ML) methods are efficient at data extraction, capable of processing the information-rich free... Show moreBackground Electronic health records (EHRs) offer a wealth of observational data. Machine-learning (ML) methods are efficient at data extraction, capable of processing the information-rich free-text physician notes in EHRs. The clinical diagnosis contained therein represents physician expert opinion and is more consistently recorded than classification criteria components. Objectives To investigate the overlap and differences between rheumatoid arthritis patients as identified either from EHR free-text through the extraction of the rheumatologist diagnosis using machine-learning (ML) or through manual chart-review applying the 1987 and 2010 RA classification criteria. Methods Since EHR initiation, 17,662 patients have visited the Leiden rheumatology outpatient clinic. For ML, we used a support vector machine (SVM) model to identify those who were diagnosed with RA by their rheumatologist. We trained and validated the model on a random selection of 2000 patients, balancing PPV and sensitivity to define a cutoff, and assessed performance on a separate 1000 patients. We then deployed the model on our entire patient selection (including the 3000). Of those, 1127 patients had both a 1987 and 2010 EULAR/ACR criteria status at 1 year after inclusion into the local prospective arthritis cohort. In these 1127 patients, we compared the patient characteristics of RA cases identified with ML and those fulfilling the classification criteria. Results The ML model performed very well in the independent test set (sensitivity=0.85, specificity=0.99, PPV=0.86, NPV=0.99). In our selection of patients with both EHR and classification information, 373 were recognized as RA by ML and 357 and 426 fulfilled the 1987 or 2010 criteria, respectively. Eighty percent of the ML-identified cases fulfilled at least one of the criteria sets. Both demographic and clinical parameters did not differ between the ML extracted cases and those identified with EULAR/ACR classification criteria. Conclusions With ML methods, we enable fast patient extraction from the huge EHR resource. Our ML algorithm accurately identifies patients diagnosed with RA by their rheumatologist. This resulting group of RA patients had a strong overlap with patients identified using the 1987 or 2010 classification criteria and the baseline (disease) characteristics were comparable. ML-assisted case labeling enables high-throughput creation of inclusive patient selections for research purposes. Show less
