Myositis-associated antibodies predict the severity of lung involvement in adult patients with inflammatory myositis - a cohort study of 70 adult patients with myositis in a single center.

Introduction: Idiopathic inflammatory myopathies (IIMs) encompass a diverse group of diseases characterized by considerable variability in clinical manifestations, antibody profiles, and responsiveness to immunosuppressive therapies. This study aimed to investigate the association between organ involvement and distinct myositis autoantibodies in individuals with IIM in a single-center cohort. Methods: Patients with ICD diagnoses M33.1, M33.2, M33.9, or M609 who (1) had been tested with Euroline blot assay for myositis autoantibodies and (2) met the classification criteria of definite/probable polymyositis (PM) or dermatomyositis (DM), anti-synthetase syndrome (ASS), or inclusion body myositis (IBM) were included. Medical journals were retrospectively examined with respect to clinical disease features. Results: Seventy patients (median age 58 years; 66% females) were included and represented the following diagnosis: PM (n = 23), DM (n = 21), ASS (n = 23), and IBM (n = 3). Most of the patients (87%) presented a muscle biopsy indicative of myositis. The presence of autoantibodies was as follows: myositis-specific antibodies, MSA (n = 53), myositis-associated antibodies, MAA (n = 33), both MSA + MAA (n = 24), MSA only (n = 29), MAA only (n = 9), no MSA, or MAA (n = 8). Anti-Jo-1 was the most common MSA (19%), whereas the most common MAA was anti-Ro/SSA52 (31%). We observed a significant association between antibody patterns and lung disease. In our cohort, 47% of the patients in the whole study group, 86% of patients with anti-SSA52, and 100% with anti-Jo-1 had pulmonary involvement. Patients with both MSA and MAA had a higher incidence of lung disease and decreased CO-diffusion capacity. This was especially prominent in anti-Ro/SSA52-positive patients. Interestingly, none of the patients suffered from lung disease if only antibodies against Mi-2α, Mi-2ß, NXP2, HMGCR, and TIF1γ were present or no MSA/MAA were detected. Discussion: The simultaneous presence of both MAA and MSA indicates an increased risk of lung involvement in patients with inflammatory myopathies. The presence of any MAA, and especially anti-Ro/SSA52, is associated with more severe pulmonary disease. Our data suggest that MAA antibodies might be relevant markers for early detection and treatment of lung involvement in IIM.

Metabolic signature and proteasome activity controls synovial migration of CDC42hiCD14+ cells in rheumatoid arthritis.

Objective: Activation of Rho-GTPases in macrophages causes inflammation and severe arthritis in mice. In this study, we explore if Rho-GTPases define the joint destination of pathogenic leukocytes, the mechanism by which they perpetuate rheumatoid arthritis (RA), and how JAK inhibition mitigates these effects. Methods: CD14+ cells of 136 RA patients were characterized by RNA sequencing and cytokine measurement to identify biological processes and transcriptional regulators specific for CDC42 hiCD14+ cells, which were summarized in a metabolic signature (MetSig). The effect of hypoxia and IFN-γ signaling on the metabolic signature of CD14+ cells was assessed experimentally. To investigate its connection with joint inflammation, the signature was translated into the single-cell characteristics of CDC42 hi synovial tissue macrophages. The sensitivity of MetSig to the RA disease activity and the treatment effect were assessed experimentally and clinically. Results: CDC42 hiCD14+ cells carried MetSig of genes functional in the oxidative phosphorylation and proteasome-dependent cell remodeling, which correlated with the cytokine-rich migratory phenotype and antigen-presenting capacity of these cells. Integration of CDC42 hiCD14+ and synovial macrophages marked with MetSig revealed the important role of the interferon-rich environment and immunoproteasome expression in the homeostasis of these pathogenic macrophages. The CDC42 hiCD14+ cells were targeted by JAK inhibitors and responded with the downregulation of immunoproteasome and MHC-II molecules, which disintegrated the immunological synapse, reduced cytokine production, and alleviated arthritis. Conclusion: This study shows that the CDC42-related MetSig identifies the antigen-presenting CD14+ cells that migrate to joints to coordinate autoimmunity. The accumulation of CDC42 hiCD14+ cells discloses patients perceptive to the JAKi treatment.

Gene expression of S100a8/a9 predicts Staphylococcus aureus-induced septic arthritis in mice.

Septic arthritis is the most aggressive joint disease associated with high morbidity and mortality. The interplay of the host immune system with the invading pathogens impacts the pathophysiology of septic arthritis. Early antibiotic treatment is crucial for a better prognosis to save the patients from severe bone damage and later joint dysfunction. To date, there are no specific predictive biomarkers for septic arthritis. Transcriptome sequencing analysis identified S100a8/a9 genes to be highly expressed in septic arthritis compared to non-septic arthritis at the early course of infection in an Staphylococcus aureus septic arthritis mouse model. Importantly, downregulation of S100a8/a9 mRNA expression at the early course of infection was noticed in mice infected with the S. aureus Sortase A/B mutant strain totally lacking arthritogenic capacity compared with the mice infected with parental S. aureus arthritogenic strain. The mice infected intra-articularly with the S. aureus arthritogenic strain significantly increased S100a8/a9 protein expression levels in joints over time. Intriguingly, the synthetic bacterial lipopeptide Pam2CSK4 was more potent than Pam3CSK4 in inducing S100a8/a9 release upon intra-articular injection of these lipopeptides into the mouse knee joints. Such an effect was dependent on the presence of monocytes/macrophages. In conclusion, S100a8/a9 gene expression may serve as a potential biomarker to predict septic arthritis, enabling the development of more effective treatment strategies.

Inclusion body myositis with early onset: a population-based study.

INTRODUCTION: Inclusion body myositis (IBM), an inflammatory myopathy with progressive weakness without efficient treatment, typically presents after 45 years of age and younger patients are sparsely studied. METHODS: In a population-based study during a 33-year period, 142 patients with IBM were identified in western Sweden. Six patients fell outside the European Neuromuscular Centre 2011 criteria for IBM due to young age at symptom onset, verified by a muscle biopsy < 50 years of age. These were defined as early-onset IBM and included in this study. Medical records, muscle strength, comorbidities, muscle biopsies, and nuclear- and mitochondrial DNA were examined and compared with patients with IBM and age matched controls from the same population. RESULTS: The median age at symptom onset was 36 (range 34-45) years and at diagnosis 43 (range 38-58) years. Four patients were deceased at a median age of 59 (range 50-75) years. The median survival from diagnosis was 14 (range 10-18) years. The prevalence December 31 2017 was 1.2 per million inhabitants and the mean incidence 0.12 patients per million inhabitants and year. The mean decline in quadriceps strength ± 1 standard deviation was 1.21 ± 0.2 Newton or 0.91 ± 0.2% per month and correlated to time from diagnosis (p < 0.001). Five patients had swallowing difficulties. All patients displayed mitochondrial changes in muscle including cytochrome c oxidase deficiency and the mitochondrial DNA mutation load was high. CONCLUSIONS: Early-onset IBM is a severe disease, causing progressive muscle weakness, high muscle mitochondrial DNA mutation load and a reduced cumulative survival in young and middle-aged individuals.

Antieosinophil Antibodies Alone or in Combination with Antineutrophil Cytoplasmic Antibodies (ANCA) Detected in Different Autoimmune Conditions.

Circulating antieosinophil antibodies (AEOSA) have been associated with various autoimmune conditions affecting the liver, kidneys, lungs, and joints but are not part of routine clinical diagnostics. While analyzing human sera for antineutrophil cytoplasmic antibodies (ANCA) by indirect immunofluorescence (IIF) on granulocytes, 0.8% of analyzed samples were found to be reactive with eosinophils. Our aim was to determine the diagnostic relevance and antigenic specificity of AEOSA. AEOSA were seen either in combination with an myeloperoxidase (MPO)-positive p-ANCA (44%; AEOSA+/ANCA+) or on their own (56%; AEOSA+/ANCA-). AEOSA/ANCA positivity was seen in patients with thyroid disease (44%) or vasculitis (31%), while AEOSA+/ANCA- pattern was more common in patients with autoimmune disorders of the gastrointestinal tract and/or liver. Eosinophil peroxidase (EPX) was the main target recognized in 66% of the AEOSA+ sera by enzyme-linked immunosorbent assay (ELISA). Eosinophil cationic protein (ECP) and eosinophil-derived neurotoxin (EDN) were also identified as target antigens but less frequently and only in combination with EPX. In conclusion, we confirmed that EPX is a major target of AEOSA, illustrating the high antigenic potential of EPX. Our results also demonstrate the presence of concomitant AEOSA/ANCA positivity in a defined patient group. Further research should aim to elucidate the association of AEOSA with autoimmunity.

Stratified genetic analysis reveals sex differences in MPO-ANCA-associated vasculitis.

OBJECTIVE: To identify and genetically characterize subgroups of patients with ANCA-associated vasculitides (AAV) based on sex and ANCA subtype. METHODS: A previously established SNP dataset derived from DNA sequencing of 1853 genes and genotyping of 1088 Scandinavian cases with AAV and 1589 controls was stratified for sex and ANCA subtype and analysed for association with five top AAV SNPs. rs9274619, a lead variant at the HLA-DQB1/HLA-DQA2 locus previously associated with AAV positive for myeloperoxidase (MPO)-ANCA, was analysed for association with the cumulative disease involvement of ten different organ systems. RESULTS: rs9274619 showed a significantly stronger association to MPO-ANCA-positive females than males [P = 2.0 × 10-4, OR = 2.3 (95% CI 1.5, 3.5)], whereas proteinase 3 (PR3)-ANCA-associated variants rs1042335, rs9277341 (HLA-DPB1/A1) and rs28929474 (SERPINA1) were equally associated with females and males with PR3-ANCA. In MPO-ANCA-positive cases, carriers of the rs9274619 risk allele were more prone to disease engagement of eyes [P = 0.021, OR = 11 (95% CI 2.2, 205)] but less prone to pulmonary involvement [P = 0.026, OR = 0.52 (95% CI 0.30, 0.92)]. Moreover, AAV with both MPO-ANCA and PR3-ANCA was associated with the PR3-ANCA lead SNP rs1042335 [P = 0.0015, OR = 0.091 (95% CI 0.0022, 0.55)] but not with rs9274619. CONCLUSIONS: Females and males with MPO-ANCA-positive AAV differ in genetic predisposition to disease, suggesting at least partially distinct disease mechanisms between the sexes. Double ANCA-positive AAV cases are genetically similar to PR3-ANCA-positive cases, providing clues to the clinical follow-up and treatment of these patients.

The Impact of Aging and Toll-like Receptor 2 Deficiency on the Clinical Outcomes of Staphylococcus aureus Bacteremia.

Staphylococcus aureus (S. aureus) causes a broad range of infections. Toll-like receptor (TLR) 2 senses the S. aureus lipoproteins in S. aureus infections. Aging raises the risk of infection. Our aim was to understand how aging and TLR2 affect the clinical outcomes of S. aureus bacteremia. Four groups of mice (wild type/young, wild type/old, TLR2-/-/young, and TLR2-/-/old) were intravenously infected with S. aureus, and the infection course was followed. Both TLR2 deficiency and aging enhanced the susceptibility to disease. Increased age was the main contributing factor for increased mortality rates and changes in spleen weight, whereas other clinical parameters, such as weight loss and kidney abscess formation, were more TLR2 dependent. Importantly, aging increased mortality rates without relying on TLR2. In vitro, both aging and TLR2 deficiency down-regulated cytokine/chemokine production of immune cells with distinct patterns. In summary, we demonstrate that aging and TLR2 deficiency impair the immune response to S. aureus bacteremia in distinct ways.

Clinical Significance of Diabetes-Mellitus-Associated Antibodies in Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a canonical autoimmune disease that shares numerous risk factors with diabetes mellitus (DM). The production of autoantibodies is a characteristic feature in both diseases. To determine the frequency and specificity of DM-related antibodies (DMab) in RA patients and to study whether DMab associates with new DM cases in RA patients, we measured DMab defined as IgG against glutamic acid decarboxylase (GADA), tyrosine phosphatase (IA2-ab), and zinc transporter (ZnT8-ab) in a cohort of 290 RA patients (215 women and 75 men, median disease duration 11 years). Of those, 21 had a DM diagnosis at baseline. The development of new DM cases and mortality were traced in a 10-year prospective follow-up. Predictive analyses for DM and mortality were carried out by the Mantel-Cox regression. We found that 27 of the patients (9.3%) had DMab, equally often men and women. The presence of DMab was more frequent in patients with DM (p = 0.027. OR 4.01, 95%CI [1.20; 11.97]), suggesting their specificity for the disease. Men had more prevalent incidental DM at the baseline (12% vs. 5%, p = 0.030) and among the new DM cases (p = 0.012. HR 6.08, 95%CI [1.57; 25]). New DM developed equally frequently in DMab-positive and DMab-negative patients. DM, but not DMab, significantly increased the estimated mortality rate in RA patients (p = 0.021, OR 4.38 [1.2; 13.52]). Taken together, we conclude that DMab are associated with DM in RA patients, but they are not solely enough to predict disease development or mortality in those patients.

Staphylococcus aureus lipoproteins in infectious diseases.

Infections with the Gram-positive bacterial pathogen Staphylococcus aureus remain a major challenge for the healthcare system and demand new treatment options. The increasing antibiotic resistance of S. aureus poses additional challenges, consequently inflicting a huge strain in the society due to enormous healthcare costs. S. aureus expresses multiple molecules, including bacterial lipoproteins (Lpps), which play a role not only in immune response but also in disease pathogenesis. S. aureus Lpps, the predominant ligands of TLR2, are important for bacterial survival as they maintain the metabolic activity of the bacteria. Moreover, Lpps possess many diverse properties that are of vital importance for the bacteria. They also contribute to host cell invasion but so far their role in different staphylococcal infections has not been fully defined. In this review, we summarize the current knowledge about S. aureus Lpps and their distinct roles in various infectious disease animal models, such as septic arthritis, sepsis, and skin and soft tissue infections. The molecular and cellular response of the host to S. aureus Lpp exposure is also a primary focus.

Phenol-soluble modulin α and ß display divergent roles in mice with staphylococcal septic arthritis.

Phenol-soluble modulin α (PSMα) is identified as potent virulence factors in Staphylococcus aureus (S. aureus) infections. Very little is known about the role of PSMß which belongs to the same toxin family. Here we compared the role of PSMs in S. aureus-induced septic arthritis in a murine model using three isogenic S. aureus strains differing in the expression of PSMs (Newman, Δpsmα, and Δpsmß). The effects of PSMs on neutrophil NADPH-oxidase activity were determined in vitro. We show that the PSMα activates neutrophils via the formyl peptide receptor (FPR) 2 and reduces their NADPH-oxidase activity in response to the phorbol ester PMA. Despite being a poor neutrophil activator, PSMß has the ability to reduce the neutrophil activating effect of PSMα and to partly reverse the effect of PSMα on the neutrophil response to PMA. Mice infected with S. aureus lacking PSMα had better weight development and lower bacterial burden in the kidneys compared to mice infected with the parental strain, whereas mice infected with bacteria lacking PSMß strain developed more severe septic arthritis accompanied with higher IL-6 and KC. We conclude that PSMα and PSMß play distinct roles in septic arthritis: PSMα aggravates systemic infection, whereas PSMß protects arthritis development.

IGF1R signalling is a guardian of self-tolerance restricting autoantibody production.

Objective: Insulin-like growth factor 1 receptor (IGF1R) acts at the crossroad between immunity and cancer, being an attractive therapeutic target in these areas. IGF1R is broadly expressed by antigen-presenting cells (APC). Using mice immunised with the methylated albumin from bovine serum (BSA-immunised mice) and human CD14+ APCs, we investigated the role that IGF1R plays during adaptive immune responses. Methods: The mBSA-immunised mice were treated with synthetic inhibitor NT157 or short hairpin RNA to inhibit IGF1R signalling, and spleens were analysed by immunohistology and flow cytometry. The levels of autoantibody and cytokine production were measured by microarray or conventional ELISA. The transcriptional profile of CD14+ cells from blood of 55 patients with rheumatoid arthritis (RA) was analysed with RNA-sequencing. Results: Inhibition of IGF1R resulted in perifollicular infiltration of functionally compromised S256-phosphorylated FoxO1+ APCs, and an increased frequency of IgM+CD21+ B cells, which enlarged the marginal zone (MZ). Enlargement of MHCII+CD11b+ APCs ensured favourable conditions for their communication with IgM+ B cells in the MZ. The reduced expression of ICOSL and CXCR5 by APCs after IGF1R inhibition led to impaired T cell control, which resulted in autoreactivity of extra-follicular B cells and autoantibody production. In the clinical setting, the low expression of IGF1R on CD14+ APCs was associated with an involuted FOXO pathway, non-inflammatory cell metabolism and a high IL10 production characteristic for tolerogenic macrophages. Furthermore, autoantibody positivity was associated with low IGF1R signalling in CD14+ APCs. Conclusions: In experimental model and in patient material, this study demonstrates that IGF1R plays an important role in preventing autoimmunity. The study raises awareness of that immune tolerance may be broken during therapeutic IGF1R targeting.

IgA rheumatoid factor in rheumatoid arthritis.

OBJECTIVES: Rheumatoid factor (RF) is a well-established marker for the diagnosis and classification of rheumatoid arthritis (RA). Most studies evaluated IgM RF or isotype-nonspecific total RF assays. We evaluated the added value of IgA RF in this context. METHODS: An international sample cohort consisting of samples from 398 RA patients and 1073 controls was tested for IgA RF with 3 commercial assays. For all RA patients and 100 controls essential clinical and serological data for ACR/EULAR classification were available. RESULTS: The sensitivity of IgA RF for diagnosing RA was lower than the sensitivity of IgM RF. Differences in numerical values between IgA RF assays were observed. With all assays, the highest IgA RF values were found in patients with primary Sjögren's syndrome. Double positivity for IgM RF and IgA RF had a higher specificity for RA than either IgM RF or IgA RF. The sensitivity of double positivity was lower than the sensitivity of either IgA RF or IgM RF. Single positivity for IgA RF was at least as prevalent in controls than in RA patients. Adding IgA RF to IgM RF and anti-citrullinated protein antibodies (ACPA) did not affect RA classification. However, combined positivity for IgA RF, IgM RF and IgG ACPA had a higher specificity and lower sensitivity for RA classification than positivity for either of the antibodies. CONCLUSIONS: IgA RF showed a lower sensitivity than IgM RF. Combining IgA RF with IgM RF and ACPA did not improve sensitivity of RA classification. Combined positivity (IgA-RF/IgM-RF/ACPA) increased specificity.

Standardisation of ACPA tests: evaluation of a new candidate reference preparation.

INTRODUCTION: Commercial assays measuring antibodies to citrullinated protein/peptide (ACPA) show poor quantitative agreement. The diagnostic industry has never adopted the International Union of Immunological Societies-Centers for Disease Control and Prevention (IUIS-CDC) ACPA reference standard. Recently, the National Institute for Biological Standards and Control (NIBSC) prepared a new candidate ACPA standard (18/204). We evaluated both reference materials using different commercially available ACPA assays. MATERIALS AND METHODS: This is an international study in which the NIBSC candidate ACPA standard and the IUIS-CDC ACPA reference material were analysed together with 398 diagnostic samples from individuals with rheumatoid arthritis (RA) and in 1073 individuals who did not have RA using nine commercial ACPA assays. RESULTS: For both reference materials and samples from individuals with RA and individuals who did not have RA, there were large differences in quantitative ACPA results between assays. For most assays, values for the IUIS-CDC standard were lower than values for NIBSC 18/204 and the IUIS-CDC/NIBSC ratio was comparable for several, but not all assays. When NIBSC 18/204 was used as a calibrator, an improvement in alignment of ACPA results across several of the evaluated assays was obtained. Moreover, NIBSC 18/204 could align clinical interpretation for some but not all assays. CONCLUSION: Adoption of an international standard for ACPA determination is highly desirable. The candidate NIBSC 18/204 standard improved the standardisation and alignment of most ACPA assays and might therefore be recommended to be used as reference in commercial assays.

Epidemiology, Survival, and Clinical Characteristics of Inclusion Body Myositis.

OBJECTIVE: We performed a population-based study on inclusion body myositis with the primary aims to define the prevalence, survival rate, and incidence, and to investigate the symptom profiles associated with disease duration and sex over a 33-year period. METHODS: Patients diagnosed between 1985 and 2017 in Region Västra Götaland, Sweden, were identified according to the European Neuromuscular Centre diagnostic criteria from 2011. RESULTS: We identified 128 patients, 89 men and 39 women, with the strict clinicopathological definition of inclusion body myositis. The prevalence was 32 per million inhabitants, 19 per million women and 45 per million men, by December 31, 2017. Mean incidence was 2.5 per million inhabitants and year. Mean age at symptom onset was 64.4 years with quadriceps weakness being the most common presenting symptom followed by finger flexor weakness. Dysphagia was a common presenting symptom being more frequent in women (23%) than men (10%) and was during the disease course reported in 74% of men and 84% of women. Seventy-three patients were deceased, with a mean survival of 14 years from symptom onset. Survival rates from both diagnosis date and symptom onset were decreased compared to the matched population. Twenty-one percent of the patients had an additional autoimmune disease. A cross-sectional analysis of autoantibodies in 50 patients and 28 matched controls showed autoantibodies to cytosolic 5'-nucleotidase 1A in 40% of the patients and 3.6% of controls. INTERPRETATION: Inclusion body myositis is an autoimmune disease with decreased survival rate and with marked sex differences in both prevalence and clinical manifestations. ANN NEUROL 2022;92:201-212.

Multicentre study to improve clinical interpretation of rheumatoid factor and anti-citrullinated protein/peptide antibodies test results.

BACKGROUND: Rheumatoid factor (RF) and anti-citrullinated protein/peptide antibodies (ACPA) are important biomarkers for diagnosis of rheumatoid arthritis (RA). However, there is poor harmonisation of RF and ACPA assays. The aim of this study was to refine RF and ACPA interpretation across commercial assays. MATERIALS AND METHODS: Six total RF isotype-non-specific assays, 3 RF IgM isotype-specific assays and 9 ACPA immunoglobulin G assays of 13 different companies were evaluated using 398 diagnostic samples from patients with RA and 1073 disease controls. RESULTS: Using cut-offs proposed by the manufacturer, there was a large variability in diagnostic sensitivity and specificity between assays. Thresholds of antibody levels were determined based on predefined specificities and used to define test result intervals. Test result interval-specific likelihood ratios (LRs) were concordant across the different RF and ACPA assays. For all assays, the LR for RA increased with increasing antibody level. Higher LRs were found for ACPA than for RF. ACPA levels associated with LRs >80 were found in a substantial fraction (>22%) of patients with RA. CONCLUSION: Defining thresholds for antibody levels and assigning test result interval-specific LRs allows alignment of clinical interpretation for all RF and ACPA assays.

Lipoproteins Cause Bone Resorption in a Mouse Model of Staphylococcus aureus Septic Arthritis.

Septic arthritis, most often caused by Staphylococcus aureus, is a rapidly progressive and destructive joint disease with substantial mortality and morbidity. Staphylococcus aureus lipoproteins (Lpps) are known to induce arthritis and bone destruction. Here, we aimed to investigate the bone resorptive effect of S. aureus Lpps in a murine arthritis model by intra-articular injection of purified S. aureus Lpps, synthetic lipopeptides, and live S. aureus strains. Analyses of the bone mineral density (BMD) of the distal femur bone were performed. Intra-articular injection of both live S. aureus and purified S. aureus Lpps were shown to significantly decrease total- and trabecular BMD. Liquid chromatography-mass spectrometry analyses revealed that the Lpps expressed by S. aureus SA113 strain contain both diacyl and triacyl lipid moieties. Interestingly, synthetic diacylated lipopeptide, Pam2CSK4, was more potent in inducing bone resorption than synthetic triacylated lipopeptide, Pam3CSK4. Modified lipoproteins lacking the lipid moiety were deprived of their bone resorptive abilities. Monocyte depletion by clodronate liposomes fully abrogated the bone resorptive capacity of S. aureus lipoproteins. Our data suggest that S. aureus Lpps induce bone resorption in locally-induced murine arthritis, an effect mediated by their lipid-moiety through monocytes/macrophages.

The presence of serum anti-SARS-CoV-2 IgA appears to protect primary health care workers from COVID-19.

The patterns of humoral and cellular responses to SARS-CoV-2 were studied in Swedish primary health care workers (n = 156) for 6 months during the Covid-19 pandemic. Serum IgA and IgG to SARS-CoV-2, T-cell proliferation and cytokine secretion, demographic and clinical data, PCR-verified infection, and self-reported symptoms were monitored. The multivariate method OPLS-DA was used to identify immune response patterns coupled to protection from Covid-19. Contracting Covid-19 was associated with SARS-CoV-2-specific neutralizing serum IgG, T cell, IFN-γ, and granzyme B responses to SARS-CoV-2, self-reported typical Covid-19 symptoms, male sex, higher BMI, and hypertension. Not contracting Covid-19 was associated with female sex, IgA-dominated, or no antibody responses to SARS-CoV-2, airborne allergy, and smoking. The IgG-responders had SARS-CoV-2-specific T-cell responses including a cytotoxic CD4+ T-cell population expressing CD25, CD38, CD69, CD194, CD279, CTLA-4, and granzyme B. IgA-responders with no IgG response to SARS-CoV-2 constituted 10% of the study population. The IgA responses were partially neutralizing and only seen in individuals who did not succumb to Covid-19. To conclude, serum IgG-dominated responses correlated with T-cell responses to SARS-CoV-2 and PCR-confirmed Covid-19, whereas IgA-dominated responses correlated with not contracting the infection.

Identification and functional characterization of a novel susceptibility locus for small vessel vasculitis with MPO-ANCA.

OBJECTIVE: To identify and characterize genetic loci associated with the risk of developing ANCA-associated vasculitides (AAV). METHODS: Genetic association analyses were performed after Illumina sequencing of 1853 genes and subsequent replication with genotyping of selected single nucleotide polymorphisms in a total cohort of 1110 Scandinavian cases with granulomatosis with polyangiitis or microscopic polyangiitis, and 1589 controls. A novel AAV-associated single nucleotide polymorphism was analysed for allele-specific effects on gene expression using luciferase reporter assay. RESULTS: PR3-ANCA+ AAV was significantly associated with two independent loci in the HLA-DPB1/HLA-DPA1 region [rs1042335, P = 6.3 × 10-61, odds ratio (OR) 0.10; rs9277341, P = 1.5 × 10-44, OR 0.22] and with rs28929474 in the SERPINA1 gene (P = 2.7 × 10-10, OR 2.9). MPO-ANCA+ AAV was significantly associated with the HLA-DQB1/HLA-DQA2 locus (rs9274619, P = 5.4 × 10-25, OR 3.7) and with a rare variant in the BACH2 gene (rs78275221, P = 7.9 × 10-7, OR 3.0), the latter a novel susceptibility locus for MPO-ANCA+ granulomatosis with polyangiitis/microscopic polyangiitis. The rs78275221-A risk allele reduced luciferase gene expression in endothelial cells, specifically, as compared with the non-risk allele. CONCLUSION: We identified a novel susceptibility locus for MPO-ANCA+ AAV and propose that the associated variant is of mechanistic importance, exerting a regulatory function on gene expression in specific cell types.

The impact of the COVID-19 pandemic on autoimmune diagnostics in Europe: A lesson to be learned.

INTRODUCTION: The first wave of COVID-19 pandemic has disrupted almost all areas of the health care services to some extent throughout the world. Although the negative impact of COVID-19 on patients with autoimmune diseases has also been recognized, available data in this regard are limited. In the current study of the European Autoimmunity Standardisation Initiative (EASI) we aimed to provide reliable data on the extent of the impact of COVID-19 pandemic on test requests for different autoantibodies in European countries. METHODS: Data on test numbers and on the number of positive results were collected in 97 clinical laboratories from 15 European countries on a monthly basis for the year before (2019) and the year during (2020) the COVID-19 pandemic. RESULTS: A reduction in the number of autoantibody tests was observed in all European countries in the year 2020 compared to 2019. The reduction affected all autoantibody tests with an overall decrease of 13%, ranging from 1.4% (Switzerland) to 25.5% (Greece). In all countries, the decrease was most pronounced during the first wave of the pandemic (March-May 2020) with an overall decrease in those three months of 45.2%. The most affected autoantibodies were those commonly requested by general practitioners (anti-tTG IgA (-71%), RF IgM (-66%) and ACPA (-61%)). In the second wave of the pandemic (October-December 2020) the decrease was less pronounced (6.8%). With respect to the rate of positive results, subtle differences were observed for distinct autoantibodies during the pandemic, but the total rate of positive results was similar in both years. CONCLUSIONS: Our study demonstrated a strong decrease in autoantibody requests during the first wave of the COVID-19 pandemic in 15 European countries. The second wave was characterized by a less pronounced impact, with some participating countries hardly affected, while some other countries experienced a second decline. The decrease was clearly associated with the level of lock-down and with the required adjustments in the health care systems in different countries, supporting the importance of an effective strategy for the coordination of autoimmune testing in challenging situations as the COVID-19 pandemic.

Impact of the Uncoupling Protein 1 on Cardiovascular Risk in Patients with Rheumatoid Arthritis.

Adiposity is strongly associated with cardiovascular (CV) morbidity. Uncoupling protein 1 (UCP1) increases energy expenditure in adipocytes and may counteract adiposity. Our objective was to investigate a connection between UCP1 expression and cardiovascular health in patients with rheumatoid arthritis (RA) in a longitudinal observational study. Transcription of UCP1 was measured by qPCR in the subcutaneous adipose tissue of 125 female RA patients and analyzed with respect to clinical parameters and the estimated CV risk. Development of new CV events and diabetes mellitus was followed for five years. Transcription of UCP1 was identified in 89 (71%) patients. UCP1 positive patients had often active RA disease (p = 0.017), high serum levels of IL6 (p = 0.0025) and were frequently overweight (p = 0.015). IL-6hiBMIhi patients and patients treated with IL6 receptor inhibitor tocilizumab had significantly higher levels of UCP1 compared to other RA patients (p < 0.0001, p = 0.032, respectively). Both UCP1hi groups displayed unfavorable metabolic profiles with high plasma glucose levels and high triglyceride-to-HDL ratios, which indicated insulin resistance. Prospective follow-up revealed no significant difference in the incidence of new CV and metabolic events in the UCP1hi groups and remaining RA patients. The study shows that high transcription of UCP1 in adipose tissue is related to IL6-driven processes and reflects primarily metabolic CV risk in female RA patients.