Heterogeneous nuclear RNPs as targets of autoantibodies in systemic rheumatic diseases

Novel autoantibodies help diagnose anti-SSA antibody negative Sjögren disease and predict abnormal labial salivary gland pathology

OBJECTIVES

Sjögren disease (SjD) diagnosis often requires either positive anti-SSA antibodies or a labial salivary gland biopsy with a positive focus score (FS). One-third of patients with SjD lack anti-SSA antibodies (SSA-), requiring a positive FS for diagnosis. Our objective was to identify novel autoantibodies to diagnose 'seronegative' SjD.

METHODS

IgG binding to a high-density whole human peptidome array was quantified using sera from SSA- SjD cases and matched non-autoimmune controls. We identified the highest bound peptides using empirical Bayesian statistical filters, which we confirmed in an independent cohort comprising SSA- SjD (n=76), sicca-controls without autoimmunity (n=75) and autoimmune-feature controls (SjD features but not meeting SjD criteria; n=41). In this external validation, we used non-parametric methods for binding abundance and controlled false discovery rate in group comparisons. For predictive modelling, we used logistic regression, model selection methods and cross-validation to identify clinical and peptide variables that predict SSA- SjD and FS positivity.

RESULTS

IgG against a peptide from D-aminoacyl-tRNA deacylase (DTD2) bound more in SSA- SjD than sicca-controls (p=0.004) and combined controls (sicca-controls and autoimmune-feature controls combined; p=0.003). IgG against peptides from retroelement silencing factor-1 and DTD2 were bound more in FS-positive than FS-negative participants (p=0.010; p=0.012). A predictive model incorporating clinical variables showed good discrimination between SjD versus control (area under the curve (AUC) 74%) and between FS-positive versus FS-negative (AUC 72%).

CONCLUSION

We present novel autoantibodies in SSA- SjD that have good predictive value for SSA- SjD and FS positivity.

Novel autoantibodies help diagnose anti-SSA antibody negative Sjögren's disease and predict abnormal labial salivary gland pathology

Objectives

Sj□gren's disease (SjD) diagnosis requires either positive anti-SSA antibodies or a labial salivary gland biopsy with a positive focus score (FS). One-third of SjD patients lack anti-SSA antibodies (SSA-), requiring a positive FS for diagnosis. Our objective was to identify novel autoantibodies to diagnose 'seronegative' SjD.

Methods

IgG binding to a high density whole human peptidome array was quantified using sera from SSA- SjD cases and matched non-autoimmune controls. We identified the highest bound peptides using empirical Bayesian statistical filters, which we confirmed in an independent cohort comprising SSA- SjD (n=76), sicca controls without autoimmunity (n=75), and autoimmune controls (SjD features but not meeting SjD criteria; n=41). In this external validation, we used non-parametric methods for peptide abundance and controlled false discovery rate in group comparisons. For predictive modeling, we used logistic regression, model selection methods, and cross-validation to identify clinical and peptide variables that predict SSA- SjD and FS positivity.

Results

IgG against a peptide from D-aminoacyl-tRNA deacylase (DTD2) was bound more in SSA- SjD than sicca controls (p=.004) and more than combined controls (sicca and autoimmune controls combined; p=0.003). IgG against peptides from retroelement silencing factor-1 (RESF1) and DTD2, were bound more in FS-positive than FS-negative participants (p=.010; p=0.012). A predictive model incorporating clinical variables showed good discrimination between SjD versus control (AUC 74%) and between FS-positive versus FS-negative (AUC 72%).

Conclusion

We present novel autoantibodies in SSA- SjD that have good predictive value for SSA- SjD and FS-positivity.

KEY MESSAGES

What is already known on this topic - Seronegative (anti-SSA antibody negative [SSA-]) Sjögren's disease (SjD) requires a labial salivary gland biopsy for diagnosis, which is challenging to obtain and interpret. What this study adds - We identified novel autoantibodies in SSA- SjD that, when combined with readily available clinical variables, provide good predictive ability to discriminate 1) SSA- SjD from control participants and 2) abnormal salivary gland biopsies from normal salivary gland biopsies. How this study might affect research, practice or policy - This study provides novel diagnostic antibodies addressing the critical need for improvement of SSA- SjD diagnostic tools.

An Autoantigen Atlas From Human Lung HFL1 Cells Offers Clues to Neurological and Diverse Autoimmune Manifestations of COVID-19

COVID-19 is accompanied by a myriad of both transient and long-lasting autoimmune responses. Dermatan sulfate (DS), a glycosaminoglycan crucial for wound healing, has unique affinity for autoantigens (autoAgs) from apoptotic cells. DS-autoAg complexes are capable of stimulating autoreactive B cells and autoantibody production. We used DS-affinity proteomics to define the autoantigen-ome of lung fibroblasts and bioinformatics analyses to study the relationship between autoantigenic proteins and COVID-induced alterations. Using DS-affinity, we identified an autoantigen-ome of 408 proteins from human HFL1 cells, at least 231 of which are known autoAgs. Comparing with available COVID data, 352 proteins of the autoantigen-ome have thus far been found to be altered at protein or RNA levels in SARS-CoV-2 infection, 210 of which are known autoAgs. The COVID-altered proteins are significantly associated with RNA metabolism, translation, vesicles and vesicle transport, cell death, supramolecular fibrils, cytoskeleton, extracellular matrix, and interleukin signaling. They offer clues to neurological problems, fibrosis, smooth muscle dysfunction, and thrombosis. In particular, 150 altered proteins are related to the nervous system, including axon, myelin sheath, neuron projection, neuronal cell body, and olfactory bulb. An association with the melanosome is also identified. The findings from our study illustrate a connection between COVID infection and autoimmunity. The vast number of COVID-altered proteins with high intrinsic propensity to become autoAgs offers an explanation for the diverse autoimmune complications in COVID patients. The variety of autoAgs related to mRNA metabolism, translation, and vesicles suggests a need for long-term monitoring of autoimmunity in COVID. The COVID autoantigen atlas we are establishing provides a detailed molecular map for further investigation of autoimmune sequelae of the pandemic, such as “long COVID” syndrome.

A Master Autoantigen-ome Links Alternative Splicing, Female Predilection, and COVID-19 to Autoimmune Diseases

Chronic and debilitating autoimmune sequelae pose a grave concern for the post-COVID-19 pandemic era. Based on our discovery that the glycosaminoglycan dermatan sulfate (DS) displays peculiar affinity to apoptotic cells and autoantigens (autoAgs) and that DS-autoAg complexes cooperatively stimulate autoreactive B1 cell responses, we compiled a database of 751 candidate autoAgs from six human cell types. At least 657 of these have been found to be affected by SARS-CoV-2 infection based on currently available multi-omic COVID data, and at least 400 are confirmed targets of autoantibodies in a wide array of autoimmune diseases and cancer. The autoantigen-ome is significantly associated with various processes in viral infections, such as translation, protein processing, and vesicle transport. Interestingly, the coding genes of autoAgs predominantly contain multiple exons with many possible alternative splicing variants, short transcripts, and short UTR lengths. These observations and the finding that numerous autoAgs involved in RNA-splicing showed altered expression in viral infections suggest that viruses exploit alternative splicing to reprogram host cell machinery to ensure viral replication and survival. While each cell type gives rise to a unique pool of autoAgs, 39 common autoAgs associated with cell stress and apoptosis were identified from all six cell types, with several being known markers of systemic autoimmune diseases. In particular, the common autoAg UBA1 that catalyzes the first step in ubiquitination is encoded by an X-chromosome escape gene. Given its essential function in apoptotic cell clearance and that X-inactivation escape tends to increase with aging, UBA1 dysfunction can therefore predispose aging women to autoimmune disorders. In summary, we propose a model of how viral infections lead to extensive molecular alterations and host cell death, autoimmune responses facilitated by autoAg-DS complexes, and ultimately autoimmune diseases. Overall, this master autoantigen-ome provides a molecular guide for investigating the myriad of autoimmune sequalae to COVID-19 and clues to the rare but reported adverse effects of the currently available COVID vaccines.

hnRNP A/B Proteins: An Encyclopedic Assessment of Their Roles in Homeostasis and Disease

The hnRNP A/B family of proteins is canonically central to cellular RNA metabolism, but due to their highly conserved nature, the functional differences between hnRNP A1, A2/B1, A0, and A3 are often overlooked. In this review, we explore and identify the shared and disparate homeostatic and disease-related functions of the hnRNP A/B family proteins, highlighting areas where the proteins have not been clearly differentiated. Herein, we provide a comprehensive assembly of the literature on these proteins. We find that there are critical gaps in our grasp of A/B proteins' alternative splice isoforms, structures, regulation, and tissue and cell-type-specific functions, and propose that future mechanistic research integrating multiple A/B proteins will significantly improve our understanding of how this essential protein family contributes to cell homeostasis and disease.

An autoantigen profile of human A549 lung cells reveals viral and host etiologic molecular attributes of autoimmunity in COVID-19

We aim to establish a comprehensive COVID-19 autoantigen atlas in order to understand autoimmune diseases caused by SARS-CoV-2 infection. Based on the unique affinity between dermatan sulfate and autoantigens, we identified 348 proteins from human lung A549 cells, of which 198 are known targets of autoantibodies. Comparison with current COVID data identified 291 proteins that are altered at protein or transcript level in SARS-CoV-2 infection, with 191 being known autoantigens. These known and putative autoantigens are significantly associated with viral replication and trafficking processes, including gene expression, ribonucleoprotein biogenesis, mRNA metabolism, translation, vesicle and vesicle-mediated transport, and apoptosis. They are also associated with cytoskeleton, platelet degranulation, IL-12 signaling, and smooth muscle contraction. Host proteins that interact with and that are perturbed by viral proteins are a major source of autoantigens. Orf3 induces the largest number of protein alterations, Orf9 affects the mitochondrial ribosome, and they and E, M, N, and Nsp proteins affect protein localization to membrane, immune responses, and apoptosis. Phosphorylation and ubiquitination alterations by viral infection define major molecular changes in autoantigen origination. This study provides a large list of autoantigens as well as new targets for future investigation, e.g., UBA1, UCHL1, USP7, CDK11A, PRKDC, PLD3, PSAT1, RAB1A, SLC2A1, platelet activating factor acetylhydrolase, and mitochondrial ribosomal proteins. This study illustrates how viral infection can modify host cellular proteins extensively, yield diverse autoantigens, and trigger a myriad of autoimmune sequelae. Our work provides a rich resource for studies into “long COVID” and related autoimmune sequelae.

An Autoantigen-ome from HS-Sultan B-Lymphoblasts Offers a Molecular Map for Investigating Autoimmune Sequelae of COVID-19

To understand how COVID-19 may induce autoimmune diseases, we have been compiling an atlas of COVID-autoantigens (autoAgs). Using dermatan sulfate (DS) affinity enrichment of autoantigenic proteins extracted from HS-Sultan lymphoblasts, we identified 362 DS-affinity proteins, of which at least 201 (56%) are confirmed autoAgs. Comparison with available multi-omic COVID data shows that 315 (87%) of the 362 proteins are affected in SARS-CoV-2 infection via altered expression, interaction with viral components, or modification by phosphorylation or ubiquitination, at least 186 (59%) of which are known autoAgs. These proteins are associated with gene expression, mRNA processing, mRNA splicing, translation, protein folding, vesicles, and chromosome organization. Numerous nuclear autoAgs were identified, including both classical ANAs and ENAs of systemic autoimmune diseases and unique autoAgs involved in the DNA replication fork, mitotic cell cycle, or telomerase maintenance. We also identified many uncommon autoAgs involved in nucleic acid and peptide biosynthesis and nucleocytoplasmic transport, such as aminoacyl-tRNA synthetases. In addition, this study found autoAgs that potentially interact with multiple SARS-CoV-2 Nsp and Orf components, including CCT/TriC chaperonin, insulin degrading enzyme, platelet-activating factor acetylhydrolase, and the ezrin-moesin-radixin family. Furthermore, B-cell-specific IgM-associated ER complex (including MBZ1, BiP, heat shock proteins, and protein disulfide-isomerases) is enriched by DS-affinity and up-regulated in B-cells of COVID-19 patients, and a similar IgH-associated ER complex was also identified in autoreactive pre-B1 cells in our previous study, which suggests a role of autoreactive B1 cells in COVID-19 that merits further investigation. In summary, this study demonstrates that virally infected cells are characterized by alterations of proteins with propensity to become autoAgs, thereby providing a possible explanation for infection-induced autoimmunity. The COVID autoantigen-ome provides a valuable molecular resource and map for investigation of COVID-related autoimmune sequelae and considerations for vaccine design.

An Autoantigen Profile of Human A549 Lung Cells Reveals Viral and Host Etiologic Molecular Attributes of Autoimmunity in COVID-19

We aim to establish a comprehensive COVID-19 autoantigen atlas in order to understand autoimmune diseases caused by SARS-CoV-2 infection. Based on the unique affinity between dermatan sulfate and autoantigens, we identified 348 proteins from human lung A549 cells, of which 198 are known targets of autoantibodies. Comparison with current COVID data identified 291 proteins that are altered at protein or transcript level in SARS-CoV-2 infection, with 191 being known autoantigens. These known and putative autoantigens are significantly associated with viral replication and trafficking processes, including gene expression, ribonucleoprotein biogenesis, mRNA metabolism, translation, vesicle and vesicle-mediated transport, and apoptosis. They are also associated with cytoskeleton, platelet degranulation, IL-12 signaling, and smooth muscle contraction. Host proteins that interact with and that are perturbed by viral proteins are a major source of autoantigens. Orf3 induces the largest number of protein alterations, Orf9 affects the mitochondrial ribosome, and they and E, M, N, and Nsp proteins affect protein localization to membrane, immune responses, and apoptosis. Phosphorylation and ubiquitination alterations by viral infection define major molecular changes in autoantigen origination. This study provides a large list of autoantigens as well as new targets for future investigation, e.g., UBA1, UCHL1, USP7, CDK11A, PRKDC, PLD3, PSAT1, RAB1A, SLC2A1, platelet activating factor acetylhydrolase, and mitochondrial ribosomal proteins. This study illustrates how viral infection can modify host cellular proteins extensively, yield diverse autoantigens, and trigger a myriad of autoimmune sequelae.

An Autoantigen Atlas from Human Lung HFL1 Cells Offers Clues to Neurological and Diverse Autoimmune Manifestations of COVID-19

COVID-19 is accompanied by a myriad of both transient and long-lasting autoimmune responses. Dermatan sulfate (DS), a glycosaminoglycan crucial for wound healing, has unique affinity for autoantigens (autoAgs) from apoptotic cells. DS-autoAg complexes are capable of stimulating autoreactive B cells and autoantibody production. Using DS affinity, we identified an autoantigenome of 408 proteins from human fetal lung fibroblast HFL11 cells, at least 231 of which are known autoAgs. Comparing with available COVID data, 352 proteins of the autoantigenome have thus far been found to be altered at protein or RNA levels in SARS-Cov-2 infection, 210 of which are known autoAgs. The COVID-altered proteins are significantly associated with RNA metabolism, translation, vesicles and vesicle transport, cell death, supramolecular fibrils, cytoskeleton, extracellular matrix, and interleukin signaling. They offer clues to neurological problems, fibrosis, smooth muscle dysfunction, and thrombosis. In particular, 150 altered proteins are related to the nervous system, including axon, myelin sheath, neuron projection, neuronal cell body, and olfactory bulb. An association with the melanosome is also identified. The findings from our study illustrate a strong connection between viral infection and autoimmunity. The vast number of COVID-altered proteins with propensity to become autoAgs offers an explanation for the diverse autoimmune complications in COVID patients. The variety of autoAgs related to mRNA metabolism, translation, and vesicles raises concerns about potential adverse effects of mRNA vaccines. The COVID autoantigen atlas we are establishing provides a detailed molecular map for further investigation of autoimmune sequelae of the pandemic.

Association of the Polymorphism rs13259960 in SLEAR With Predisposition to Systemic Lupus Erythematosus

OBJECTIVE

Genome-wide association studies have identified many susceptibility loci for systemic lupus erythematosus (SLE). However, most of these loci are located in noncoding regions of the genome. Long noncoding RNAs (lncRNAs) are pervasively expressed and have been reported to be involved in various diseases. This study aimed to explore the genetic significance of lncRNAs in SLE.

METHODS

A genome-wide survey of SLE risk variants in lncRNA gene loci was performed in Han Chinese subjects (4,556 with SLE and 9,451 healthy controls). The functional relevance of an SLE risk variant in one of the lncRNA genes was explored using biochemical and molecular cell biology analyses. In vitro loss-of-function and gain-of-function strategies were used to clarify the functional and phenotypic relevance of this SLE susceptibility lncRNA. Moreover, correlation of this lncRNA with the degree of apoptosis in the peripheral blood of SLE patients was evaluated.

RESULTS

A novel SLE susceptibility locus in a lncRNA gene, designated SLEAR (for SLE-associated RNA), was identified at the single-nucleotide polymorphism rs13259960 (odds ratio 1.35, P_combined = 1.03 × 10^-11 ). The A>G variation at rs13259960, located in an intronic enhancer, was found to impair STAT1 recruitment to the enhancer that loops to the SLEAR promoter, resulting in decreased SLEAR production in peripheral blood mononuclear cells from patients with SLE (3 with the G/G genotype, 22 with A/G, and 103 with A/A at rs13259960; P = 0.0241). Moreover, SLEAR interacted with the RNA binding proteins interleukin enhancer binding factor 2, heterogeneous nuclear RNP F, and TATA-binding protein-associated factor 15, to form a complex for transcriptional activation of the downstream antiapoptotic genes. In addition, SLEAR regulated apoptosis of Jurkat cells in vitro, and its expression level was correlated with the degree of cell death in the peripheral blood of patients with SLE (r = 0.824, P = 2.15 × 10^-8 ; n = 30).

CONCLUSION

These findings suggest a mechanism by which the risk variant at rs13259960 modulates SLEAR expression and confers a predisposition to SLE. Taken together, these results may give insights into the etiology of SLE.

HnRNP A1 is Involved in Deep Vein Thrombosis Patients with Behçet's Disease

Objective

The aim of this study was to verify the hypothesis originated from bioinformatics and literature reviews that hnNRP A1 may be a new immune target of Behçet's disease (BD).

Methods

First, bioinformatics was used to show the correlation between hnRNP A1 and A2/B1 in amino acid sequences and three dimensional structures. Second, hnRNP A1 was expressed, purified, and immunologically confirmed by systematic immunology methods including: Western blotting, immunoprecipitation and Dot-ELISA. Then, ELISA was used to screen the anti-hnRNP A1 autoantibodies in newly confirmed clinical samples and the clinical significance was compared between anti-hnRNP A1 antibody positive and negative groups. Finally, the endothelial cells antigen profile of one anti-hnRNP A1 antibody positive BD patient was detected using immunoprecipitation with liquid chromatography tandem mass spectrometry (LC–TMS).

Results

In total 720 subjects enrolled and tested in this study. Our results demonstrated hnRNP A1 as a new immune target of BD. The reactivity of BD serum IgG antibodies against hnRNP A1 was significantly higher than healthy controls (P < 0.0001), and deep vein thrombosis (DVT) showed a significant higher in the anti-hnRNP A1 antibodies positive group (P < 0.05).

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Bioinformatics was used to predict that hnRNP A1 may play a role in BD.

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HnRNP A1 was immunologically confirmed as an autoantigen of BD.

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Deep vein thrombosis has a close relationship with anti-hnRNP A1 antibody in patients' blood circulation.

Behçet's disease (BD) is a chronic systemic autoimmune disease. The pathogenesis of BD is still not clear, and the diagnosis is based on typical clinical syndromes. Autoantigen identification was considered a key to solve this problem. This study was to verify the hypothesis suggested by bioinformatics that hnRNP A1 may be a new autoantigen of BD. Among the 720 subjects enrolled and systemic tested, our results demonstrated hnRNP A1 as a new autoantigen of BD, and associated with deep vein thrombosis.

Antibodies to native and citrullinated RA33 (hnRNP A2/B1) challenge citrullination as the inciting principle underlying loss of tolerance in rheumatoid arthritis

BACKGROUND

Anti-citrullinated protein antibodies (ACPAs) are the hallmark of rheumatoid arthritis (RA). Protein citrullination is believed to drive autoantigen selection in RA. Nonetheless, several autoantigens in RA are targeted as native (unmodified) proteins. Here, the study of hnRNP A2/B1 (RA33) provides a framework to understand the humoral response to native and citrullinated autoantigens in RA.

METHODS

RA synovial fluid (SF) cells were analysed by immunoblotting and mass spectrometry. RA33 was cloned from RASF cells and splice variants expressed as recombinant proteins. Antibodies against native and citrullinated RA33 were characterised by ELISA, immunoblotting and immunoprecipitation.

RESULTS

RA33 is citrullinated in the rheumatoid joint and targeted either as a citrullinated or native protein in distinct patient subsets with RA. A novel splice variant (hnRNP B1b) previously associated with disease initiation in experimental arthritis was identified in the RA joint and acts as the major target of the anti-RA33 response. Antibodies exclusively targeting citrullinated RA33 were positively associated with disease duration and erosive disease. In contrast, anti-(native) RA33 antibodies were detected almost exclusively in early RA and identified patients with low radiographic erosion scores. Finally, a unique subset of double-reactive patients demonstrated intermediate severity, but rapid disease progression, suggesting a transitional disease phase in the evolution of an anti-native protein antibody to ACPA response in RA.

CONCLUSIONS

These data suggest that native and citrullinated proteins targeted by autoantibodies in RA may be part of a single antibody system and challenge the paradigm of citrullination as the unifying principle underlying loss of tolerance in RA.

Proteomic identification of heterogeneous nuclear ribonucleoprotein K as a novel cold-associated autoantigen in patients with secondary Raynaud's phenomenon

OBJECTIVE

The aim of this study was to identify cold-associated autoantibodies in patients with RP secondary to CTDs.

METHODS

Indirect immunofluorescence staining was performed on non-permeabilized cold-stimulated normal human dermal microvascular endothelial cells (dHMVECs), using patients' sera. Cold-induced alterations in cell surface proteomes were analysed by isobaric tag for relative and absolute quantitation (iTRAQ) analysis. Serological proteome analysis (SERPA) was applied to screen cold-associated autoantigens. The prevalence of the candidate autoantibody was determined by ELISA in 290 patients with RP secondary to CTDs (SSc, SLE or MCTD), 10 patients with primary RP and 27 healthy controls.

RESULTS

Enhanced cell surface immunoreactivity was detected in cold-stimulated dHMVECs when incubated with sera from patients with secondary RP. By iTRAQ analysis, many proteins, including heterogeneous nuclear ribonucleoprotein K (hnRNP-K), were found to be increased on the cell surface of dHMVECs after cold stimulation. By the SERPA approach, hnRNP-K was identified as a candidate autoantigen in patients with secondary RP. Cold-induced translocation of hnRNP-K to the cell surface was confirmed by immunoblotting and flow cytometry. By ELISA analysis, patients with secondary RP show a significantly higher prevalence of anti-hnRNP-K autoantibody (30.0%, 61/203) than patients without RP (9.2%, 8/87, P = 0.0001), patients with primary RP (0%, 0/10, P = 0.0314) or healthy controls (0%, 0/27, P = 0.0001).

CONCLUSION

By comprehensive proteomics, we identified hnRNP-K as a novel cold-associated autoantigen in patients with secondary RP. Anti-hnRNP-K autoantibody may potentially serve as a biomarker for RP secondary to various CTDs.

Anti-hnRNP B1 (RA33) autoantibodies are associated with the clinical phenotype in Russian patients with rheumatoid arthritis and systemic sclerosis

Heterogeneous nuclear ribonucleoproteins (hnRNPs) are potent autoantigenic targets in systemic autoimmune rheumatic diseases (SARD). Loss of tolerance to the RA33 complex consisting of hnRNP A2 and its alternatively spliced variants B1 and B2 has been the interest of rheumatologists. A novel ELISA for the detection of anti-hnRNP B1 autoantibodies has been developed to investigate the prevalence thereof in 397 patients with SARD, including patients with rheumatoid arthritis (RA), spondyloarthropathy (SPA), juvenile chronic arthritis, systemic lupus erythematosus (SLE), systemic sclerosis (SSc), and Sjögren's syndrome (SS), in comparison to 174 controls. Anti-hnRNP B1 autoantibodies were significantly more prevalent in patients with SARD than controls (47/397, 11.8% versus 2/174, 1.1%; P < 0.001). In particular, anti-hnRNP B1 were found more frequently in the disease cohorts than in the controls and were present in 24/165 (14.5%) patients with RA, 6/58 (10.3%) SPA, 11/65 (16.9%) SSc, and 4/50 (8.0%) SLE. In RA patients, anti-hnRNP B1 autoantibodies correlated significantly with C-reactive protein levels and erythrocyte sedimentation rate, while in patients with SSc it was associated with features of arterial wall stiffness and presence of hypertension. Anti-hnRNP B1 autoantibodies occur in SARD and seem to be correlated with distinct clinical characteristics in patients with RA and SSc.

Auto-antibodies and their association with clinical findings in women diagnosed with microscopic colitis

Background

Microscopic colitis (MC) is a disease manifested by diarrhoea and is divided into collagenous and lymphocytic colitis. The aetiology is unknown, but auto-immunity is suggested. Auto-antibodies have been only rarely examined in this entity. The aim of the study was to examine the prevalence of auto-antibodies, and to examine associations between the presence of antibodies and clinical findings.

Methods and Findings

Women with MC verified by biopsy and younger than 73 years, at any Department of Gastroenterology, in the district of Skåne, between 2002 and 2010 were invited to participate in this study. The patients were asked to complete both a questionnaire describing their medical history and the Gastrointestinal Symptom Rating Scale (GSRS). Blood samples were collected. Anti-nuclear antibodies (ANA), anti-neutrophil cytoplasmic antibodies (ANCA), anti-Saccharomyces cerevisiae antibodies (ASCA), and antibodies against glutamic acid decarboxylase (anti-GAD), islet antigens-like insulin 2 (anti-IA2), thyroid peroxidase (anti-TPO), and thyrotropin receptor (TRAK) were analysed. Of 240 women identified, 133 were finally included in the study, median age 63 (59–67) years. Apart from the MC diagnosis, 52% also suffered from irritable bowel syndrome, 31% from hypertension and 31% from allergy. The prevalence of ANA (14%), ASCA IgG (13%), and anti-TPO antibodies (14%) for these patients was slightly higher than for the general population, and were found together with other concomitant diseases. Patients had more of all gastrointestinal symptoms compared with norm values, irrespective of antibody expression.

Conclusions

Women with MC have a slightly increased prevalence of some auto-antibodies. These antibodies are not associated with symptoms, but are expressed in patients with concomitant diseases, obscuring the pathophysiology and clinical picture of MC.