Systemic lupus erythematosus, Sjögren's syndrome, and dermatomyositis are systemic autoimmune diseases that develop after environmental triggering of genetically susceptible individuals. The precise ...cellular and molecular mechanisms leading to autoimmune disease, and what factors determine which organs are involved, remain poorly understood. Recent insights into genetic susceptibility now make obvious that environmental triggers often act via cellular pathways containing disease-associated polymorphisms. In the breaking of tolerance, the initiating tissue—including dendritic cells—provides a decisive microenvironment that affects immune-cell differentiation, leading to activation of adaptive immunity. Type 1 interferon produced by innate immune cells has a central role in systemic autoimmunity and activates B cells and T cells. In turn, B-cell-derived autoantibodies stimulate dendritic cells to produce type 1 interferon; thus, a positive feedforward loop is formed that includes both the innate and adaptive systems. New treatments could simultaneously and specifically target several such vital pathways in autoimmunity.
Systemic autoimmune diseases such as systemic lupus erythematosus are type I IFN‐driven diseases with exaggerated B‐cell responses and autoantibody production. Th17 cells, a T‐helper‐cell subset with ...high inflammatory capacity, was initially discovered and characterized in the context of experimental autoimmune encephalomyelitis — an animal model of multiple sclerosis. There is now emerging evidence that Th17 cells, and more generally IL‐17 and IL‐17‐producing cells, may play a role in the pathogenesis of type I IFN‐driven systemic autoimmune diseases such as lupus. Here, we review the different studies suggesting a role for IL‐17 and IL‐17‐producing cells in systemic autoimmune diseases, both in humans and in animal models, and we consider the possible mechanisms by which these cells may contribute to disease. We also discuss the hypothesis that type I IFN and IL‐17 act in concert to sustain and amplify autoimmune and inflammatory responses, making them a dangerous combination involved in the pathogenesis of systemic autoimmune diseases.
Abstract Ro52 is a common target of circulating autoantibodies in autoimmune disease. Data indicate that anti-Ro52 antibodies are associated with distinct clinical manifestations. It is therefore of ...major interest to understand how it becomes an antigenic target and what cells express this protein under what conditions and what cellular function it has. Ro52 contains a RING and a B-box motif, followed by a coiled-coil domain and a B30.2 (or PRYSPRY) region in the C-terminal end. This molecular structure places Ro52 within the family of tripartite motif proteins (TRIM), and it is also denoted TRIM21. Like several other TRIM proteins, Ro52 has E3 ligase activity and functions in the process of ubiquitination. Ro52 is expressed in the immune system as a predominantly cytoplasmic protein that can be upregulated and translocate to the nucleus in a proinflammatory environment. Reported substrates for Ro52-mediated ubiquitination include IRF3, IRF5, IRF7 and IRF8, and via these transcription factors Ro52 regulates type 1 interferon and cytokine production. Ro52 is upregulated at the site of autoimmune inflammation, such as cutaneous lupus lesions. This implies that Ro52 may have an important role in the pathogenesis of autoimmunity, and this paper will review the available data on the role of Ro52 in immune responses and autoimmune pathogenesis.
Here, we present a method for in-depth human plasma proteome analysis based on high-resolution isoelectric focusing HiRIEF LC-MS/MS, demonstrating high proteome coverage, reproducibility and the ...potential for liquid biopsy protein profiling. By integrating genomic sequence information to the MS-based plasma proteome analysis, we enable detection of single amino acid variants and for the first time demonstrate transfer of multiple protein variants between mother and fetus across the placenta. We further show that our method has the ability to detect both low abundance tissue-annotated proteins and phosphorylated proteins in plasma, as well as quantitate differences in plasma proteomes between the mother and the newborn as well as changes related to pregnancy.
Autoimmune congenital heart block (CHB) may develop in foetuses of women carrying anti‐Ro/SSA and La/SSB autoantibodies and is characterized by disruption of signal conduction at the atrioventricular ...(AV) node, resulting in partial or complete AV block. If not fatal in utero, complete CHB typically requires lifelong cardiac pacing. No treatment has so far been unequivocally demonstrated to prevent or treat autoimmune CHB, and the relatively low incidence (1%‐5%) and recurrence (12%‐16%) rates of second/third‐degree AV block add to the complexity of managing pregnancies in women with anti‐Ro/La antibodies. Altogether, a better understanding of events leading to development of autoimmune CHB is needed to improve surveillance and treatment strategies. In the past decade, studies have started to look beyond the role of maternal autoantibodies in disease pathogenesis to assess other contributing factors such as foetal genetics and, more recently, immune responses in foetuses and neonates of anti‐Ro/La antibody‐positive women. In this review, we provide an update on the epidemiology, clinical presentation and current treatment approaches of autoimmune CHB, summarize the previously proposed pathogenic mechanisms implicating maternal autoantibodies, and discuss the recent findings of type I interferon (IFN) and innate immune activation in foetuses with autoimmune CHB and in neonates of anti‐Ro/La antibody‐positive mothers, and how these may contribute to autoimmune CHB pathogenesis.
Patients with systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (pSS) are typically characterized by the presence of autoantibodies and an IFN-signature. The strength of the ...IFN-signature positively correlates with disease severity, suggesting that type I IFNs are active players in these diseases. BAFF is a cytokine critical for development and proper selection of B cells, and the targeting of BAFF has emerged as a successful treatment strategy of SLE. Previous reports have suggested that BAFF expression is directly induced by type I IFNs, but the precise mechanism for this remains unknown. In this article, we demonstrate that BAFF is a bona fide ISG and that IFN regulatory factors (IRFs) control the expression of BAFF. We identify IRF1 and IRF2 as positive regulators of BAFF transcription and IRF4 and IRF8 as potent repressors; in addition, we have mapped the precise binding site for these factors in the BAFF promoter. IFN-β injections induced BAFF expression mainly in neutrophils and monocytes, and BAFF expression in neutrophils from pSS patients strongly correlated with the strength of the IFN-signature. In summary, we show that BAFF expression is directly induced by type I IFNs via IRF1 and IRF2, whereas IRF4 and IRF8 are negative regulators of BAFF expression. These data suggest that type I IFN blockade in SLE and pSS patients will lead to downregulation of BAFF and a consequential reduction of autoreactive B cell clones and autoantibodies.
Abstract
Primary SS (pSS) is a rheumatic disease characterized by an immune-mediated exocrinopathy, resulting in severe dryness of eyes and mouth. Systemic symptoms include fatigue and joint pain and ...a subset of patients develop more severe disease with multi-organ involvement. Accumulating evidence points to involvement of innate immunity and aberrant activity of the type I IFN system in both the initiation and propagation of this disease. Analysis of the activity of IFN-inducible genes has evidenced that more than half of pSS patients present with a so-called ‘type I IFN signature’. In this review, we examine activation of the IFN system in pSS patients and how this may drive autoimmunity through various immune cells. We further discuss the clinical value of assessing IFN activity as a biomarker in pSS patients and review novel therapies targeting IFN signalling and their potential use in pSS.
Introduction
We investigated the effects of maternal autoimmune disease and fetal congenital heart block (CHB) on pregnancy outcomes in anti‐Ro/SSA‐positive women and assessed the population‐based ...incidence of isolated CHB.
Material and methods
One hundred and ninety nine anti‐Ro/SSA‐positive pregnancies were prospectively followed at our center (2000–2013). Seven fetuses developed atrioventricular block (AVB) II–III. In this period, another 13 anti‐Ro/SSA‐positive pregnancies were referred for fetal bradycardia, subsequently diagnosed with AVB II–III. Cesarean section rates, gestational age, body measurements at birth, and the incidence of CHB in these 212 pregnancies were analyzed in relation to fetal atrioventricular conduction and maternal diagnosis and compared with data from the Medical Birth Registry on 352 104 pregnancies in the Stockholm County.
Results
The prevalence of maternal systemic lupus erythematosus (SLE) and primary Sjögren's syndrome and the outcomes at birth were similar in normal conduction and AVB I cases. Only 1/20 AVB II–III cases (0/7 in the surveillance group) had a mother diagnosed with SLE, compared with 73/192 in cases with normal conduction or AVB I. Excluding cases with AVB II–III, SLE mothers more frequently delivered by cesarean section (31% vs. 20%, p < 0.05) and had a higher incidence of preterm birth (13% vs. 5.8%, p < 0.05) than the county population. Both SLE and primary Sjögren's syndrome mothers had a fourfold greater rate of growth‐retarded babies (10.11% vs. 2.2%, p < 0.001). The incidence of autoantibody‐related AVB II–III in Stockholm County was 1/23 300.
Conclusion
This study of CHB provides new information on the incidence of CHB and outcome of pregnancy in anti‐Ro/SSA‐positive women, which has clinical relevance when counseling rheumatic patients considering pregnancy.
During pregnancy in autoimmune conditions, maternal autoantibodies are transported across the placenta and may affect the developing fetus. Congenital heart block (CHB) is known to associate with the ...presence of anti-Ro/SSA and anti-La/SSB antibodies in the mother and is characterized by a block in signal conduction at the atrioventricular (AV) node. The mortality rate of affected infants is 15% to 30%, and most live-born children require lifelong pacemaker implantation. Despite a well-recognized association with maternal anti-Ro/La antibodies, CHB develops in only 1% to 2% of anti-Ro-positive pregnancies, indicating that other factors are important for establishment of the block. The molecular mechanisms leading to complete AV block are still unclear, and the existing hypotheses fail to explain all aspects of CHB in one comprehensive model. In this review, we discuss the different specificities of maternal autoantibodies that have been implicated in CHB as well as the molecular mechanisms that have been suggested to operate, focusing on the evidence supporting a direct pathogenic role of maternal antibodies. Autoantibodies targeting the 52-kDa component of the Ro antigen remain the antibodies most closely associated with CHB. In vitro experiments and animal models of CHB also point to a major role for anti-Ro52 antibodies in CHB pathogenesis and suggest that these antibodies may directly affect calcium regulation in the fetal heart, leading to disturbances in signal conduction or electrogenesis or both. In addition, maternal antibody deposits are found in the heart of fetuses dying of CHB and are thought to contribute to an inflammatory reaction that eventually induces fibrosis and calcification of the AV node, leading to a complete block. Considering that CHB has a recurrence rate of 12% to 20% despite persisting maternal autoantibodies, it has long been clear that maternal autoantibodies are not sufficient for the establishment of a complete CHB, and efforts have been made to identify additional risk factors for this disorder. Therefore, recent studies looking at the influence of genetic and environmental factors will also be discussed.
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