Objectives Myositis-specific and myositis-associated autoantibodies (MSA/MAA) are important biomarkers used in the diagnosis and assessment of patients with idiopathic inflammatory myopathies. To date, limited guidance exists on how testing should be undertaken or which MSA/MAA to include in a clinically justifiable ‘myositis panel’. We aimed to investigate interlaboratory variability in 'myositis autoantibody testing' in terms of panel components, comparability of test results and approaches to reporting with a view to informing future guidelines. Methods Twenty-four quality-control sera containing MSA/MAA were shared with 15 participating laboratories located in Europe, North America, Australia and Japan. Laboratories evaluated the samples for MSA/MAA using their usual protocols. Raw data, alongside reported test results, were collated. Results Participating laboratories made use of a variety of commercial and in-house assays. Most used at least one commercial multiplex assay and each centre tested for between 14 and 33 autoantibody specificities. Near 100% concordance in the reported result was seen for almost half the samples analysed. As expected, negative results were reported where the previously identified autoantibody was not tested for, but also frequently with putative anti-OJ, anti-EJ and anti-TIF1γ samples. Of concern, the results obtained for anti-TIF1γ sera varied between laboratories using the same commercial assay. Discussion We have shown there is considerable variation in how myositis antibody testing is undertaken and the results obtained for key autoantibody specificities, which may impact on clinical decision-making. Dialogue between manufacturers, diagnostic laboratories and clinicians remains crucial and steps towards harmonisation between laboratories is urgently needed.

OBJECTIVES:We developed and tested a robust case ascertainment strategy within the Clinical Practice Research Datalink (CPRD), with the aim of assessing the incidence, prevalence, mortality and delay in diagnosis of SSc in the UK. METHODS:A two-stage case ascertainment strategy was devised and tested to establish a valid cohort of SSc cases within the CPRD. Incidence, prevalence and mortality statistics were analysed, alongside evaluation of the relationship between primary care codes for RP and SSc to examine diagnostic delay. RESULTS:SSc Read codes were identified in 3123 patients (from a study cohort of >10.1 million individuals). Of these, 1757 cases of SSc were identified using our case ascertainment approach. The overall incidence rate of SSc over the period between 1999 and 2017 was 10.7/million/year (95% CI: 9.9-11.4), being higher in females [17.69/million/year (95% CI: 16.32-19.07)] than in males [3.59/million/year (95% CI: 2.97-4.21)]. The overall prevalence of SSc in adults was 235.5/million (95% CI: 207.2-245.7). The mean rate of mortality was 32/1000 person-years, with an overall standardized mortality ratio of 3.51 (95% CI: 3.19-3.84). Of those with an initial code of RP prior to a Read code of SSc, 191/854 (22.4%) had a lag period of >10 years. CONCLUSION:We have developed and tested a robust case ascertainment strategy to examine the incidence, prevalence, mortality and diagnostic delay of SSc using primary care records of over 10 million UK residents. A significant lag between coding of RP and SSc in many patients suggests diagnostic delay in SSc remains an important unmet need.

OBJECTIVES:Cardiovascular disease is a leading cause of mortality in systemic sclerosis (SSc). We investigated the association between SSc and the occurrence of both cardiovascular and thromboembolic events using the Clinical Practice Research Datalink (CPRD). METHODS:A validated case-ascertainment strategy identified SSc patients in the CPRD. A cohort study design examined rates of coronary arterial disease (CAD), cerebrovascular disease, peripheral artery disease (PAD) and venous thromboembolism (VTE) in SSc patients matched to non-SSc comparators by age, sex and location in a 1:6 ratio. Prevalent and incident cases of SSc were analysed separately. Cox regression analysis was used to determine hazard ratios for event occurrence, adjusted for traditional cardiovascular risk factors. RESULTS:We identified 877 eligible incident cases of SSc who were matched to 5262 patients without SSc (83.7% female), with a mean follow-up of 8 years. We identified a higher background prevalence of CAD, PAD and VTE at baseline (pre-dating diagnosis) in the SSc cohort. There was a significantly increased risk of CAD, PAD, peripheral venous thromboses and pulmonary embolism during follow-up in SSc compared with the non-SSc group (adjusted hazard ratios between 1.84-3.01), particularly amongst males. There was no increased risk of cerebrovascular disease. CONCLUSIONS:We have identified an increased risk of cardiovascular events and VTE, both prior to a diagnosis of SSc and within 8 years of SSc diagnosis. Work is needed to establish the mechanism of arterial/venous thrombotic events in SSc. This insight will facilitate more targeted and effective preventative strategies and improve outcomes in SSc.

OBJECTIVE:To evaluate the analytical performance of commercial myositis-specific autoantibody (MSA) assays against immunoprecipitation (IP) assays. METHODS:A systematic literature search was conducted in PubMed, Web of Science, and Scopus through July 2024. Data were extracted on study design, participant characteristics, index tests, and 2 × 2 contingency tables for diagnostic performance. Study quality was assessed using the QUADAS-2 tool. Sensitivity and specificity were calculated for each dataset and presented as paired forest plots and summary receiver operating characteristic (SROC) curves. A hierarchical SROC model was used to estimate pooled sensitivity and specificity for meta-analysis. RESULTS:Of 3156 articles, 23 met inclusion criteria and were judged to have low risk of bias across all QUADAS-2 domains. The most frequently evaluated commercial assay was the line blot assay (LBA; 16 studies), followed by enzyme immunoassay (EIA; 9 studies). In the meta-analyses, the highest pooled sensitivity was observed for anti-MDA5 with EIA (95.7 %), followed by anti-SAE with LBA (88.3 %), anti-PL-12 with LBA (87.2 %), and anti-Jo-1 and anti-MDA5 with LBA (82.8 %). Lower sensitivities were observed for anti-Mi-2 (67.4 %), anti-NXP2 (69.7 %), and anti-TIF1-γ (63.8 %) with LBA. Pooled specificity ranged from 94.7 % to 99.3 % across MSA assays, but a false-positive result was a common concern for LBA, except for anti-EJ. CONCLUSION:False-positive and false-negative results remain a significant challenge in the use of commercial MSA assays.

OBJECTIVES:Anti-transcriptional intermediary factor 1γ (TIF1γ) autoantibodies are associated with malignancy in adult-onset idiopathic inflammatory myopathy (IIM) and this risk is attenuated if patients are also positive for anti-specificity protein 4 (Sp4) or anti-cell division cycle apoptosis regulator protein 1 (CCAR1). In anti-TIF1γ positive dermatomyositis (DM) patients from the USA, anti-Sp4 and anti-CCAR1 autoantibody frequencies are reported as 32% and 43% in adults and 9% and 19% in juveniles, respectively. This study aims to identify the frequency of anti-Sp4 and anti-CCAR1 in adult and juvenile UK anti-TIF1γ-positive myositis populations and report clinical associations. METHODS:Serum samples from 51 UK participants with adult-onset IIM and 55 UK participants with JDM, all anti-TIF1γ autoantibody positive, and 24 healthy control samples were screened for anti-Sp4 and anti-CCAR1 autoantibodies by ELISA. RESULTS:In UK adult anti-TIF1γ positive IIM patients, anti-Sp4 and anti-CCAR1 frequencies were 4% (2/51) and 16% (8/51). Both adult patients with anti-Sp4 were also positive for anti-CCAR1. In UK juveniles, anti-Sp4 was not detected and 13% (7/55) had anti-CCAR1 autoantibodies. Nineteen (37%) anti-TIF1γ positive UK adult myositis patients had cancer; neither of the two patients with anti-Sp4 autoantibodies and 25% (2/8) of anti-CCAR1 autoantibody-positive patients had cancer. No anti-Sp4 or anti-CCAR1 clinical associations were identified. CONCLUSION:Anti-Sp4 and anti-CCAR1 autoantibodies are less common in the adult UK anti-TIF1γ-positive myositis population compared with published data from the USA, limiting their use as biomarkers for cancer risk. In patients with juvenile onset disease, anti-Sp4 is less frequent in UK patients compared with the USA, but the prevalence of anti-CCAR1 autoantibodies is similar.

Background/Aims Idiopathic inflammatory myopathy (IIM) is characterised by myositis, which can impact activities of daily living. The 2022 BSR IIM management guideline recommends assessing/managing factors associated with poor mental wellbeing and quality of life. Research into anxiety and depression associated with IIM is limited. This study aims to investigate associations between anxiety/depression and IIM disease activity. Methods The MYOPROSP study recruited UK adults with verified IIM throughout a 36 month period between 2016 and 2020. Patient questionnaires were collected at three, six, and 12 months. Participants completed the EQ-5D-5L questionnaire, which includes a question relating to anxiety and depression with five possible responses: "I am (not/slightly/moderately/severely/extremely) anxious or depressed". The cohort was divided by response to the EQ-5D-5L anxiety/depression question at the time of recruitment. Disease activity was assessed using International Myositis Assessment & Clinical Studies Group (IMACS) Disease Activity Core Set Measures (see Table 1) and summarised across each EQ-5D-5L anxiety/depression group. The EQ-5D-5L visual analogue scale (VAS) relating to "overall health" (higher values correspond to better health) this value was summarised across each EQ-5D-5L anxiety/depression group. Only participants with complete data at recruitment were included in analysis. One-way ANOVA was performed to determine statistical significance (p < 0.05) of each IMACS Disease Activity Core Set Measure and EQ-5D-5L VAS across anxiety/depression groups. Results Complete data on 35 participants (71% female) was collected. All participants reported to have no, slight, or moderate anxiety/depression (i.e. no participant reported severe or extreme anxiety/depression) (Table 1). The "not anxious/depressed" group demonstrated higher EQ-5D VAS values (reflecting better perceived health), shorter disease duration, and higher CK levels, compared to groups with "slight" and "moderate" anxiety/depression. All other investigated variables did not consistently vary across anxiety/depression groups. One-way ANOVA identified that only disease duration and EQ-5D VAS were significantly associated with EQ-5D-5L anxiety/depression group. Conclusion Anxiety and depression are associated with longer disease duration and poorer overall health in adults with IIM. These findings suggest that anxiety/depression in adults with IIM may be due to sustained muscle damage and resulting impacts upon activities of daily living and quality of life, rather than disease activity.

Objectives Myositis-specific and associated autoantibodies are important biomarkers in routine clinical use. We assessed local testing performance for myositis autoantibodies by comparing line immunoassay (LIA) to protein radio-immunoprecipitation and identifying clinical characteristics associated with each myositis autoantibody in the MyoCite cohort.Methods Serum samples from patients within the MyoCite cohort, a well-characterized retro-prospective dataset of adult and juvenile idiopathic inflammatory myopathy (IIM) patients in Lucknow, India (2017-2020), underwent LIA at Sanjay Gandhi Postgraduate Institute of Medical Science (SGPGIMS), Lucknow. Immunoprecipitation of 147 IIM patients' serum samples (125 adult-onset, 22 juvenile-onset) was conducted at the University of Bath, with researchers blind to LIA results. LIA performance was assessed against immunoprecipitation as the reference standard, measuring sensitivity, specificity and inter-rater agreement. Univariate and multivariate logistic regression determined clinical associations for specific myositis-specific autoantibodies.Results Immunoprecipitation identified myositis autoantibodies in 56.5% (n = 83) of patient samples, with anti-Jo1 (n = 16; 10.9%) as the most common, followed by anti-MDA5 (n = 14, 9.5%). While LIA showed good agreement for anti-Jo1, anti-PL7 and anti-PL12 (Cohen's kappa 0.79, 0.83 and 1, respectively), poor agreement was observed in other subgroups, notably anti-TIF1 gamma (Cohen's kappa 0.21). Strongly positive samples, especially in myositis-specific autoantibodies, correlated more with immunoprecipitation results. Overall, 59 (40.1%) samples exhibited non-congruence on LIA and immunoprecipitation, and kappa values for LIAs for anti-TIF1 gamma, anti-Ku, anti-PmScl, anti-Mi2 and anti-SAE ranged between 0.21 and 0.60.Conclusion While LIA reliably detected anti-Jo1, anti-PL7, anti-PL12, anti-MDA5 and anti-NXP-2, it also displayed false positives and negatives. Its effectiveness in detecting other autoantibodies, such as anti-TIF1 gamma, was poor.

. Objective. To determine the annual incidence of psoriatic arthritis (PsA) in a United Kingdom primary care population with preexisting psoriasis (PsO) followed prospectively over 2 years after excluding baseline prevalence of existing disease. Methods. Total Burden of Psoriasis (TUDOR; ISRCTN registry: ISRCTN38877516) was a multicenter, prospective, 2-arm parallel-group cluster randomized controlled trial of the early identification of PsA by annual rheumatological assessment (termed "Enhanced Surveillance") vs standard care in people with PsO identified in primary care. Incidence of PsA is reported at 12 months and 24 months using patients from the Enhanced Surveillance arm, which allows for the exclusion of patients with prevalent PsA at baseline. Results. Fourteen of 511 participants attending a 12-month screen developed PsA over that interval, giving an incidence of 2.74/100 patient-years (PYs; 95% CI 1.32-4.16). Another 7/444 participants attending the 24-month visit developed PsA, giving an incidence of 1.58/100 PYs (95% CI 0.42-2.74). The combined incidence over 2 years was 2.20/100 PYs (95% CI 1.27-3.13). Conclusion. The estimated annual incidence of PsA over a 2-year period was 2.20/100 PYs, which is in keeping with studies including clinical assessment rather than relying on health records alone. Extended follow-up of the TUDOR cohort with accrual of larger numbers of incident cases will allow risk factors for PsA to be explored in more depth.

Objectives Systemic sclerosis (SSc)-related autoantibodies are widely used diagnostic and prognostic biomarkers. This study aimed to develop a new assay for detecting anti-ribonucleoprotein autoantibodies in SSc based on RNA immunoprecipitation (RNA IP) coupled with massive parallel sequencing. Methods Serum samples and clinical data were collected from 307 SSc patients. Among these, 57 samples underwent analysis using a new protocol that combines RNA IP with massive parallel sequencing (RIP-Seq). Filtering strategies and statistical outlier detection methods were applied to select RNA molecules that could represent novel ribonucleoprotein autoantigens associated with SSc. Results Among the 30,966 different RNA molecules identified by RIP-Seq in 57 SSc patients, 197 were ultimately selected. These included all RNA molecules previously identified by RNA IP, which were found to exhibit high counts almost exclusively in samples positive for the autoantibodies associated to the corresponding RNA molecule, indicating high sensitivity and specificity of the RIP-Seq technique. C/D box snoRNAs were the most abundant RNA type identified. The immunoprecipitation patterns of the detected C/D box snoRNAs varied among patients and could be associated with different clinical phenotypes. In addition, other ribonucleoproteins were identified, which could be potential targets for previously undescribed SSc-related autoantibodies. These include H/ACA box snoRNPs, vault complexes, mitochondrial tRNA synthetases, and 7SK snRNP. Conclusion A novel RIP-Seq assay has been developed to detect autoantibodies targeting ribonucleoprotein complexes in SSc patients. This method successfully identified RNA molecules associated with ribonucleoproteins known to be targeted by SSc-related autoantibodies, validating both the assay and the analysis strategy. Additionally, this approach uncovered RNA molecules associated with ribonucleoproteins that were not previously identified as targets of SSc patients’ sera, suggesting potential new autoantibody candidates in this disease.

ObjectiveAnti-synthetase syndrome (ASSD) is a rare systemic autoimmune rheumatic disease (SARD) with significant heterogeneity and no shared classification criteria. We aimed to identify clinical and serological features associated with ASSD that may be suitable for inclusion in the data-driven classification criteria for ASSD.MethodsWe used a large, international, multicenter "Classification Criteria for Anti-synthetase Syndrome" (CLASS) project database, which includes both patients with ASSD and controls with mimicking conditions, namely, SARDs and/or interstitial lung disease (ILD). The local diagnoses of ASSD and controls were confirmed by project team members. We employed univariable logistic regression and multivariable Ridge regression to evaluate clinical and serological features associated with an ASSD diagnosis in a randomly selected subset of the cohort.ResultsOur analysis included 948 patients with ASSD and 1,077 controls. Joint, muscle, lung, skin, and cardiac involvement were more prevalent in patients with ASSD than in controls. Specific variables associated with ASSD included arthritis, diffuse myalgia, muscle weakness, muscle enzyme elevation, ILD, mechanic's hands, secondary pulmonary hypertension due to ILD, Raynaud phenomenon, and unexplained fever. In terms of serological variables, Jo-1 and non-Jo-1 anti-synthetase autoantibodies, antinuclear antibodies with cytoplasmic pattern, and anti-Ro52 autoantibodies were associated with ASSD. In contrast, isolated arthralgia, dysphagia, electromyography/magnetic resonance imaging/muscle biopsy findings suggestive of myopathy, inflammatory rashes, myocarditis, and pulmonary arterial hypertension did not differentiate between patients with ASSD and controls or were inversely associated with ASSD.ConclusionWe identified key clinical and serological variables associated with ASSD, which will help clinicians and offer insights into the development of data-driven classification criteria for ASSD.

Myositis-specific autoantibodies (MSAs) are hallmarks of idiopathic inflammatory myopathies (IIMs) and have become increasing valuable in disease diagnosis, phenotyping, and classification. In addition to their clinical utility, emerging data, including findings from several animal studies, suggest that MSAs and autoreactive T cells substantially contribute to the etiopathogenesis of IIMs. This review aims to provide an updated perspective on myositis autoantibodies by focusing on relevant clinical and translational studies.

Background: Autoantibodies are a hallmark feature of Connective Tissue Diseases (CTD). Their presence in patients with idiopathic interstitial lung disease (ILD) may suggest covert CTD. We aimed to determine the prevalence of CTD autoantibodies in patients diagnosed with idiopathic ILD. Methods: 499 patient sera were analysed: 251 idiopathic pulmonary fibrosis (IPF), 206 idiopathic non-specific interstitial pneumonia (iNSIP) and 42 cryptogenic organising pneumonia (COP). Autoantibody status was determined by immunoprecipitation. Results: 2.4% of IPF sera had a CTD-autoantibody compared to 10.2% of iNSIP and 7.3% of COP. 45% of autoantibodies were anti-synthetases. A novel autoantibody targeting an unknown 56 kDa protein was found in seven IPF patients (2.8%) and two NSIP (1%) patients. This was characterised as anti-annexin A11. Conclusion: Specific guidance on autoantibody testing and interpretation in patients with ILD could improve diagnostic accuracy. Further work is required to determine the clinical significance of anti-annexin A11.

Objective To assess current evidence for effectiveness of sequential lines of biologic and targeted small-molecule disease-modifying anti-rheumatic drugs (b/tsDMARDs) when used beyond first-line for psoriatic arthritis (PsA). Methods A systematic search of the literature (Medline, Embase, bibliographic searches) was undertaken (October and December 2022) to find studies meeting the criteria of assessing effectiveness of b/tsDMARDs beyond first-line in adults with PsA (PROSPERO CRD42022365298). Risk of bias assessment was undertaken (ROBINS-I/Cochrane RoB2). Results Of 2666 abstracts identified and following a full text review of 177 psoriatic disease studies, 12 manuscripts and two abstracts were eligible. Of the 12 manuscripts, 11 were observational and one was a sub-analysis of a RCT (n = 16 081: average age 49.5 years, female 53.3%). Two abstracts (n = 7186) were included. All studies comparing first- and second-line (three studies) found a reduced response in second-line. On average, DAPSA remission (most reported outcome, eight studies) was achieved in 26%, 19% and 10% first-, second- and third-line TNFi, and 22%, 13% and 11% first-, second- and third-line other bDMARDs, respectively. Responses varied to third-line bDMARDs; four studies found comparable second- and third-line responses, five studies found diminishing responses in sequential lines. Conclusion Predominantly observational studies, inherently at high risk of bias, indicate bDMARDs can be effective to third-line in PsA, but that response is reduced after first line. There is very limited data for more advanced lines of b/tsDMARD. Prospective studies are required to better understand clinical response to advanced lines of treatment in PsA.

Objective The CLASS (Classification Criteria of Anti-Synthetase Syndrome) project is a large international multicentre study that aims to create the first data-driven anti-synthetase syndrome (ASSD) classification criteria. Identifying anti-aminoacyl tRNA synthetase antibodies (anti-ARS) is crucial for diagnosis, and several commercial immunoassays are now available for this purpose. However, using these assays risks yielding false-positive or false-negative results, potentially leading to misdiagnosis. The established reference standard for detecting anti-ARS is immunoprecipitation (IP), typically employed in research rather than routine autoantibody testing. We gathered samples from participating centers and results from local anti-ARS testing. As an "ad-interim" study within the CLASS project, we aimed to assess how local immunoassays perform in real-world settings compared to our central definition of anti-ARS positivity. Methods We collected 787 serum samples from participating centres for the CLASS project and their local anti-ARS test results. These samples underwent initial central testing using RNA-IP. Following this, the specificity of ARS was reconfirmed centrally through ELISA, line-blot assay (LIA), and, in cases of conflicting results, protein-IP. The sensitivity, specificity, positive likelihood ratio and positive and negative predictive values were evaluated. We also calculated the inter-rater agreement between central and local results using a weighted kappa co-efficient. Results Our analysis demonstrates that local, real-world detection of anti-Jo] is reliable with high sensitivity and specificity with a very good level of agreement with our central definition of anti-Jo] antibody positivity. However, the agreement between local immunoassay and central determination of anti-non-Jo] antibodies varied, especially among results obtained using local LIA, ELISA and "other" methods. Conclusion Our study evaluates the performance of real-world identification of anti-synthetase antibodies in a large cohort of multi-national patients with ASSD and controls. Our analysis reinforces the reliability of real-world anti-Jo] detection methods. In contrast, challenges persist for anti-non-Jo] identification, particularly anti-PL7 and rarer antibodies such as anti-OJ/KS. Clinicians should exercise caution when interpreting anti-synthetase antibodies, especially when commercial immunoassays test positive for non-anti-Jo] antibodies.

Objective To obtain updated estimates on the incidence and prevalence of systemic lupus erythematosus (SLE) in the UK, over the period 1990–2020, using the Clinical Practice Research Datalink (CPRD).Methods This was a retrospective cohort study using the CPRD covering the period 1990–2020. A case ascertainment algorithm was developed in line with best practice recommendations for observational research. Incidence was calculated per 100 000 person-years and point prevalence (at the mid-year point) calculated per 100 000. Results were stratified by sex.Results 9443 SLE cases were identified. 5278 incident cases were identified (4538 women, 740 men). The overall incidence rate was 5.47 (95% CI 5.33 to 5.62) cases per 100 000 person-years. Incidence rates decreased slightly across the study period, which was more pronounced for women than men. Point prevalence increased over time, from 21.4 (95% CI 17.68 to 25.67) per 100 000 in 1990 to 107.14 (95% CI 103.26 to 111.12) per 100 000 in 2020.Conclusions The observed fivefold increase in prevalence of SLE over the last 30 years, in the context of a modest decline in incidence rate, may suggest improved outcomes in SLE and has important implications for healthcare service delivery and planning in the UK.

ObjectiveTo determine the annual incidence of psoriatic arthritis in a UK primary care population with preexisting psoriasis followed prospectively over two years after excluding baseline prevalence of existing disease.MethodsTUDOR (Total bUrDen of psORiasis) was a multi-centre, prospective, two-arm parallel-group cluster randomised controlled trial of the early identification of PsA by annual rheumatological assessment (termed Enhanced Surveillance) versus standard care in people with psoriasis identified in primary care. Incidence of psoriatic arthritis is reported at 12- and 24-months using patients from the Enhanced Surveillance arm, which allows the exclusion of patients with prevalent PsA at baseline.ResultsFourteen of 511 participants attending a 12-month screen developed PsA over that interval giving an incidence of 2.74 per 100 patient years (p-yrs) (95% CI: 1.32 to 4.16) and another 7 of 444 participants attending the 24-month visit developed PsA giving an incidence of 1.58 per 100 p-yrs (95% CI: 0.42 to 2.74). The combined incidence over 2 years was 2.20 per 100 p-yrs (95% CI: 1.27 to 3.13).ConclusionThe estimated annual incidence of PsA over a 2-year period was 2.20 per 100 p-yrs, that is in keeping with a higher incidence of PsA than that found when relying on health records alone. Extended follow-up of the TUDOR cohort with accrual of larger numbers of incident cases will allow risk factors for psoriatic arthritis to be explored in more depth.

(1) Background: Myositis specific antibodies (MSA) are important diagnostic biomarkers. Among the rarest and most challenging MSA are anti-OJ antibodies which are associated with anti-synthetase syndrome (ASS). In contrast to the other tRNA synthetases that are targets of ASS autoantibodies (e.g Jo-1, PL-7, PL-12, EJ, KS, Zo), OJ represents a macromolecular complex with several ribonucleoprotein subunits. Therefore, the choice of the antigen in autoantibody assays can be challenging. (2) Methods: We collected two independent cohorts with anti-OJ antibodies, one based on a commercial line immunoassay (LIA) (n = 39), the second based on protein immunoprecipitation (IP) (n = 15). Samples were tested using a particle-based multi-analyte technology (PMAT) system that allows for the simultaneous detection of antibodies to various autoantigens. For the detection of anti-OJ antibodies, two different antigens were deployed (KARS, IARS) on PMAT. The reactivity to the two antigens KARS and IARS was analyzed individually and combined in a score (sum of the median fluorescence intensities). (3) Results: In the cohort selection based on LIA, 3/39 (7.7%) samples were positive for anti-KARS and 7/39 (17.9%) for anti-IARS and 14/39 (35.9%) when the two antigens were combined. In contrast, in samples selected by IP the sensitivity of anti-KARS was higher: 6/15 (40.0%) samples were positive for anti-KARS, 4/15 (26.7%) for anti-IARS and 12/15 (80.0%) for the combination of the two antigens. 18/39 (46.2%) of the LIA samples generated a cytoplasmic IIF pattern (compatible with anti-synthetase antibodies), but there was no association with the antibody levels, neither with LIA nor with PMAT. (4) Conclusions: The combination of IARS and KARS might represent a promising approach for the detection of anti-OJ antibodies on a fully automated platform.

OBJECTIVES:HCQ and AZA are used to control disease activity and reduce risk of flare during pregnancy in patients with SLE. The aim of this study was to determine the outcomes of children born to mothers with SLE exposed to HCQ or AZA during pregnancy and breast-feeding. METHODS:Women attending UK specialist lupus clinics with children ≤17 years old, born after SLE diagnosis, were recruited to this retrospective study. Data were collected using questionnaires and from clinical record review. Factors associated with the outcomes of low birth weight and childhood infection were determined using multivariable mixed-effects logistic regression models. RESULTS:We analysed 284 live births of 199 mothers from 10 UK centres. The first pregnancies of 73.9% of mothers (147/199) were captured in the study; (60.4%) (150/248) and 31.1% (87/280) children were exposed to HCQ and AZA, respectively. There were no significant differences in the frequency of congenital malformations or intrauterine growth restriction between children exposed or not to HCQ or AZA. AZA use was increased in women with a history of hypertension or renal disease. Although AZA was associated with low birth weight in univariate models, there was no significant association in multivariable models. In adjusted models, exposure to AZA was associated with increased reports of childhood infection requiring hospital management [odds ratio 2.283 (1.003, 5.198), P = 0.049]. CONCLUSIONS:There were no significant negative outcomes in children exposed to HCQ in pregnancy. AZA use was associated with increased reporting of childhood infection, which warrants further study.

Background In patients with idiopathic inflammatory myopathies (IIM), autoantibodies are associated with specific clinical phenotypes suggesting a pathogenic role of adaptive immunity. We explored if autoantibody profiles are associated with specific HLA genetic variants and clinical manifestations in IIM. Methods We included 1348 IIM patients and determined the occurrence of 14 myositis-specific or-associated autoantibodies. We used unsupervised cluster analysis to identify autoantibody-defined subgroups and logistic regression to estimate associations with clinical manifestations, HLA-DRB1, HLA-DQA1, HLA-DQB1 alleles, and amino acids imputed from genetic information of HLA class II and I molecules. Findings We identified eight subgroups with the following dominant autoantibodies: anti-Ro52, -U1RNP, -PM/Scl,-Mi2,-Jo1,-Jo1/Ro52,-TIF1 gamma or negative for all analysed autoantibodies. Associations with HLA-DRB1*11, HLA-DRB1*15, HLA-DQA1*03, and HLA-DQB1*03 were present in the anti-U1RNP-dominated subgroup. HLA-DRB1*03, HLA-DQA1*05, and HLA-DQB1*02 alleles were overrepresented in the anti-PM/Scl and anti-Jo1/ Ro52-dominated subgroups. HLA-DRB1*16, HLA-DRB1*07 alleles were most frequent in anti-Mi2 and HLA- DRB1*01 and HLA-DRB1*07 alleles in the anti-TIF1 gamma subgroup. The HLA-DRB1*13, HLA-DQA1*01 and HLA-DQB1*06 alleles were overrepresented in the negative subgroup. Significant signals from variations in class I molecules were detected in the subgroups dominated by anti-Mi2, anti-Jo1/Ro52, anti-TIF1 gamma, and the negative subgroup. Interpretation Distinct HLA class II and I associations were observed for almost all autoantibody-defined subgroups. The associations support autoantibody profiles use for classifying IIM which would likely reflect underlying pathogenic mechanisms better than classifications based on clinical symptoms and/or histopathological features. Funding See a detailed list of funding bodies in the Acknowledgements section at the end of the manuscript. Copyright (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Objective Systemic lupus erythematosus (SLE) is a clinically and biologically heterogenous autoimmune disease. We aimed to investigate the plasma proteome of patients with active SLE to identify novel subgroups, or endotypes, of patients. Method Plasma was collected from patients with active SLE who were enrolled in the British Isles Lupus Assessment Group Biologics Registry (BILAG-BR). The plasma proteome was analysed using a data-independent acquisition method, Sequential Window Acquisition of All theoretical mass spectra mass spectrometry (SWATH-MS). Unsupervised, data-driven clustering algorithms were used to delineate groups of patients with a shared proteomic profile. Results In 223 patients, six clusters were identified based on quantification of 581 proteins. Between the clusters, there were significant differences in age (p = 0.012) and ethnicity (p = 0.003). There was increased musculoskeletal disease activity in cluster 1 (C1), 19/27 (70.4%) (p = 0.002) and renal activity in cluster 6 (C6) 15/24 (62.5%) (p = 0.051). Anti-SSa/Ro was the only autoantibody that significantly differed between clusters (p = 0.017). C1 was associated with p21-activated kinases (PAK) and Phospholipase C (PLC) signalling. Within C1 there were two sub-clusters (C1A and C1B) defined by 49 proteins related to cytoskeletal protein binding. C2 and C6 demonstrated opposite Rho family GTPase and Rho GDI signalling. Three proteins (MZB1, SND1 and AGL) identified in C6 increased the classification of active renal disease although this did not reach statistical significance (p = 0.0617). Conclusions Unsupervised proteomic analysis identifies clusters of patients with active SLE, that are associated with clinical and serological features, which may facilitate biomarker discovery. The observed proteomic heterogeneity further supports the need for a personalised approach to treatment in SLE.