Rheumatoid factors in systemic lupus erythematosus: association with clinical and laboratory parameters. SLE study group

Clinical and laboratory pattern of patients with systemic lupus erythematosus seropositive for rheumatoid factor

Introduction

The aim of the study was to investigate the associations between the presence and level of rheumatoid factor (RF) in the blood serum and the clinical and laboratory characteristics of patients with systemic lupus erythematosus (SLE).

Material and methods

This retrospective tricentric cross-sectional study analyzed a Ukrainian contingent of SLE patients. Medical records of 495 patients were evaluated. Rheumatoid factor serum concentration was tested in 206 of them (41.6%) using turbidimetry technique. Clinical manifestations, routine laboratory parameters, specific immunological tests, disease activity (SLEDAI-2K), and damage indices (SLICC/ACR DI) were evaluated.

Results

Our study revealed that RF was elevated in 27.7% of patients. The RF-positive patients experienced a longer delay in SLE diagnosis (2.0 vs. 0.5 years, p = 0.046), less frequent kidney involvement (42.1% vs. 59.4%, p = 0.045) and fever (42.1% vs. 59.2%, p = 0.046), and more frequent lymphadenopathy (59.6% vs. 42.3%, p = 0.039) compared to RF-negative patients. Patients with RF positivity had higher levels of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and antinuclear antibody (ANA) titer, and were more frequently positive for antibodies to Ro/SSA and La/SSB. Rheumatoid factor concentration directly correlated with CRP (r = 0.318; p < 0.01) and ESR (r = 0.228; p = 0.04) levels. However, no associations were found between RF levels and SLEDAI-2K, joint involvement frequency, SLICC/ACR DI or drug therapy content. Univariate logistic regression analysis showed that RF positivity was independently associated with lymphadenopathy, presence of anti-Ro/SSA and anti-La/SSB antibodies, and negatively associated with kidney involvement.

Conclusions

In RF-seropositive SLE patients (approximately 28%), the diagnosis is established later compared to RF-seronegative ones; kidney involvement and fever are less common, while lymphadenopathy develops more frequently. Rheumatoid factor seropositivity is associated with higher levels of ESR, CRP, ANA, and the presence of antibodies to Ro/SSA and La/SSB. According to the results of univariate logistic regression analysis, an independent association with RF positivity was confirmed only for kidney involvement, lymphadenopathy, and antibodies to Ro/SSA and La/SSB.

Associations of Rheumatoid Factor, Rheumatoid Arthritis, and Interleukin-6 Inhibitor with the Prognosis of Ischemic Stroke: a Prospective Multicenter Cohort Study and Mendelian Randomization Analysis

Rheumatoid factor (RF), an established diagnostic biomarker for rheumatoid arthritis (RA), is associated with cardiovascular diseases, but its impact on clinical outcomes of ischemic stroke remains unclear. We aimed to investigate the observational associations between serum RF and prognosis of ischemic stroke, and further examined the genetic associations of RA and its therapeutic strategy, interleukin-6 (IL-6) inhibitor, with prognosis of ischemic stroke. We measured serum RF levels in 3474 Chinese ischemic stroke patients from the China Antihypertensive Trial in Acute Ischemic Stroke. The primary outcome was the composite outcome of death or major disability (modified Rankin Scale score ≥3) at 3 months after stroke onset. Mendelian randomization (MR) analyses were performed to examine the associations of genetically predicted RA and IL-6 inhibition with prognosis of ischemic stroke. During 3 months of follow-up, 866 patients (25.43%) experienced death or major disability. After multivariate adjustment, RF-positive was significantly associated with a high risk of primary outcome (OR, 1.47; 95% CI, 1.08-2.00; P =0.016) compared with RF-negative. The two-sample MR analyses suggested that genetically predicted RA was associated with an increased risk of primary outcome (OR, 1.09; 95% CI, 1.01-1.18; P=0.021), while genetically predicted IL-6 inhibition was associated with a decreased risk of primary outcome (OR, 0.88; 95% CI, 0.77-0.99; P=0.041). We found that positive RF was associated with increased risks of adverse outcomes after atherosclerotic ischemic stroke, and genetically predicted RA and IL-6 inhibition increased and decreased the risks of adverse outcomes after ischemic stroke, respectively.

The first involved joints and associated factors in patients with rheumatoid arthritis

Objectives

This study aimed to investigate the first involved joints and associated factors in Turkish patients with rheumatoid arthritis (RA).

Patients and methods

This retrospective cross-sectional study included 300 newly diagnosed and disease-modifying antirheumatic drug-naïve RA patients (240 females, 60 males; mean age: 54±1.2 years; range, 18 to 82 years). Baseline demographic, clinical, and laboratory data were evaluated between January 2022 and December 2022. The patients were divided into four groups according to autoantibody profile: antibody-negative patients (Group 1; both RF and anti-CCP were negative in this group of patients), RF-positive patients (Group 2), anti-CCP-positive patients (Group 3), and patients with dual seropositivity with RF and antiCCP (Group 4). The patients were also divided into two groups according to the size of the first affected joint: patients with SJI at diagnosis and patients without SJI involvement at diagnosis.

Results

Rheumatoid factor (RF) and anti-cyclic citrullinated peptide (CCP) antibody positivity rates were 40.3% and 35.6%, respectively. The mean lag time to diagnosis was 25±36 months. At the disease onset, 20% of patients did not have small joint involvement (SJI). Seronegative patients tended to be female (p=0.001), had longer lag time (p=0.001), and had lower levels of C-reactive protein (p=0.025), white blood count (p=0.005), and neutrophil/lymphocyte ratio (p=0.001) compared to the dual seropositive group. Patients presenting with SJI had a younger age (p=0.002), tended to be female (p=0.001), and had lower RF (p=0.034) and anti-CCP (p=0.031) positivity. Only age (p=0.005) and dual seronegativity (RF and anti-CCP; p=0.035) were the independent predictors of SJI in multivariate analysis.

Conclusion

The decreasing age and seronegative status were defined as independent risk factors of SJI at the onset of RA. Population-based, prospective studies are needed for earlier diagnosis.

Successful Treatment of Ultrasound-confirmed Synovitis in Anti-MDA5 Antibody-positive Clinically Amyopathic Dermatomyositis with Corticosteroid Therapy

Anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive clinically amyopathic dermatomyositis (CADM) is a subtype of dermatomyositis without severe myositis but with characteristic cutaneous manifestations and severe interstitial lung disease. Joint symptoms can occur in patients with anti-MDA5 antibody-positive CADM. However, the treatment strategy and utility of ultrasound for treating joint symptoms remain unknown. We herein report an 85-year-old man with anti-MDA5 antibody-positive CADM who presented with ultrasound-confirmed synovitis that improved with medium-dose corticosteroid therapy.

Prevalence of Sjögren's syndrome according to 2016 ACR-EULAR classification criteria in patients with systemic lupus erythematosus

BACKGROUND

Diagnosis of SS is a complex task, as no symptom or test is unique to this syndrome. The American-European Consensus Group (AECG 2002) and the American-European classification criteria of 2016 (ACR/EULAR 2016) emerged through a search for consensus. This study aims to assess the prevalence of Sjögren's Syndrome (SS) in patients with Systemic Lupus Erythematosus (SLE), according to AECG 2002 and ACR-EULAR 2016 classifications, as well as clinical and histopathological features in this overlap. To date, there is no study that has evaluated SS in SLE, using the two current criteria.

METHODS

This cross-sectional study evaluated 237 SLE patients at the outpatient rheumatology clinic between 2016 and 2018. Patients were submitted to a dryness questionnaire, whole unstimulated salivary flow (WUSF), "Ocular Staining Score" (OSS), Schirmer's test I (ST-I), and labial salivary gland biopsy (LSGB).

RESULTS

After verifying inclusion and exclusion criteria, a total of 117 patients were evaluated, with predominance of females (94%) and mixed ethnicity (49.6%). The prevalence of SS was 23% according to AECG 2002 and 35% to ACR-EULAR 2016. Kappa agreement between AECG 2002 and ACR-EULAR 2016 were 0.7 (p < 0.0001). After logistic regression, predictors for SS were: anti/Ro (OR = 17.86, p < 0.05), focal lymphocytic sialadenitis (OR = 3.69, p < 0.05), OSS ≥ 5 (OR = 7.50, p < 0.05), ST I positive (OR = 2.67, p < 0.05), and WUSF ≤ 0.1 mL/min (OR = 4.13, p < 0.05).

CONCLUSION

The prevalence of SS in SLE was 23% (AECG 2002) and 35% (ACR-EULAR 2016). The presence of glandular dysfunction, focal lymphocytic sialadenitis, and anti/Ro were predictors of SS in SLE. The greatest advantage of the new ACR-EULAR 2016 criteria is to enable an early diagnosis and identify the overlapping of these two diseases. ACR-EULAR 2016 criteria is not yet validated for secondary SS and this study is a pioneer in investigating prevalence based on the new criteria.

Circulating Thrombomodulin: Release Mechanisms, Measurements, and Levels in Diseases and Medical Procedures

Thrombomodulin (TM) is a type-I transmembrane protein that is mainly expressed on endothelial cells and plays important roles in many biological processes. Circulating TM of different forms are also present in biofluids, such as blood and urine. Soluble TM (sTM), comprised of several domains of TM, is the major circulating TM which is generated by either enzymatic or chemical cleavage of the intact protein under different conditions. Under normal conditions, sTM is present in low concentrations (<10 ng/mL) in the blood but is elevated in several pathological conditions associated with endothelial dysfunction such as cardiovascular, inflammatory, infection, and metabolic diseases. Therefore, sTM level has been examined for monitoring disease development, such as disseminated intravascular coagulation (DIC), sepsis and multiple organ dysfunction syndrome in patients with novel coronavirus disease 2019 (COVID-19) recently. In addition, microvesicles (MVs) that contain membrane TM (MV-TM) have been found to be released from activated cells which also contribute to levels of circulating TM in certain diseases. Several release mechanisms of sTM and MV-TM have been reported, including enzymatic, chemical, and TM mutation mechanisms. Measurements of sTM and MV-TM have been developed and explored as biomarkers in many diseases. In this review, we summarize all these advances in three categories as follows: (1) release mechanisms of circulating TM, (2) methods for measuring circulating TM in biological samples, and (3) correlation of circulating TM with diseases. Altogether, it provides a whole picture of recent advances on circulating TM in health and disease.

Therapeutic Potential of a Novel Bifidobacterium Identified Through Microbiome Profiling of RA Patients With Different RF Levels

The potential therapeutic effects of probiotic bacteria in rheumatoid arthritis (RA) remain controversial. Thus, this study aimed to discover potential therapeutic bacteria based on the relationship between the gut microbiome and rheumatoid factor (RF) in RA. Bacterial genomic DNA was extracted from the fecal samples of 93 RA patients and 16 healthy subjects. Microbiota profiling was conducted through 16S rRNA sequencing and bioinformatics analyses. The effects of Bifidobacterium strains on human peripheral blood mononuclear cells and collagen-induced arthritis (CIA) mice were assessed. Significant differences in gut microbiota composition were observed in patients with different RF levels. The relative abundance of Bifidobacterium and Collinsella was lower in RF-high than in RF-low and RF-negative RA patients, while the relative abundance of Clostridium of Ruminococcaceae family was higher in RF-high than in RF-low and RF-negative patients. Among 10 differentially abundant Bifidobacterium, B. longum RAPO exhibited the strongest ability to inhibit IL-17 secretion. Oral administration of B. longum RAPO in CIA mice, obese CIA, and humanized avatar model significantly reduced RA incidence, arthritis score, inflammation, bone damage, cartilage damage, Th17 cells, and inflammatory cytokine secretion. Additionally, B. longum RAPO significantly inhibited Th17 cells and Th17-related genes—IL-17A, IRF4, RORC, IL-21, and IL-23R—in the PBMCs of rheumatoid arthritis patients. Our findings suggest that B. longum RAPO may alleviate RA by inhibiting the production of IL-17 and other proinflammatory mediators. The safety and efficacy of B. longum RAPO in patients with RA and other autoimmune disorders merit further investigation.

Biomarkers Associated with Organ-Specific Involvement in Juvenile Systemic Lupus Erythematosus

Juvenile systemic lupus erythematosus (JSLE) is characterised by onset before 18 years of age and more severe disease phenotype, increased morbidity and mortality compared to adult-onset SLE. Management strategies in JSLE rely heavily on evidence derived from adult-onset SLE studies; therefore, identifying biomarkers associated with the disease pathogenesis and reflecting particularities of JSLE clinical phenotype holds promise for better patient management and improved outcomes. This narrative review summarises the evidence related to various traditional and novel biomarkers that have shown a promising role in identifying and predicting specific organ involvement in JSLE and appraises the evidence regarding their clinical utility, focusing in particular on renal biomarkers, while also emphasising the research into cardiovascular, haematological, neurological, skin and joint disease-related JSLE biomarkers, as well as genetic biomarkers with potential clinical applications.

Bacterial infections in lupus: Roles in promoting immune activation and in pathogenesis of the disease

BACKGROUND

Bacterial infections of the lung, skin, bloodstream and other tissues are common in patients with systemic lupus erythematosus (lupus) and are often more severe and invasive than similar infections in control populations. A variety of studies have explored the changes in bacterial abundance in lupus patients, the rates of infection and the influence of particular bacterial species on disease progression, using both human patient samples and mouse models of lupus.

OBJECTIVE

The aim of this review is to summarize human and mouse studies that describe changes in the bacterial microbiome in lupus, the role of a leaky gut in stimulating inflammation, identification of specific bacterial species associated with lupus, and the potential roles of certain common bacterial infections in promoting lupus progression.

METHODS

Information was collected using searches of the Pubmed database for articles relevant to bacterial infections in lupus and to microbiome changes associated with lupus.

RESULTS

The reviewed studies demonstrate significant changes in the bacterial microbiome of lupus patients as compared to control subjects and in lupus-prone mice compared to control mice. Furthermore, there is evidence supporting the existence of a leaky gut in lupus patients and in lupus-prone mice. This leaky gut may allow live bacteria or bacterial components to enter the circulation and cause inflammation. Invasive bacterial infections are more common and often more severe in lupus patients. These include infections caused by Staphylococcus aureus, Salmonella enterica, Escherichia coli, Streptococcus pneumoniae and mycobacteria. These bacterial infections can trigger increased immune activation and inflammation, potentially stimulating activation of autoreactive lymphocytes and leading to worsening of lupus symptoms.

CONCLUSIONS

Together, the evidence suggests that lupus predisposes to infection, while infection may trigger worsening lupus, leading to a feedback loop that may reinforce autoimmune symptoms.

Usefulness of rheumatoid factor as an immunological and prognostic marker in PSS patients

INTRODUCTION

The rheumatoid factor (RF) is present in numerous autoimmune disorders, although its role in many of them remains a subject of research. The study assesses the role of RF as an immunological and prognostic factor in the primary Sjögren's syndrome (pSS).

METHODS

Seventy-five pSS patients (mean age 50.03 ± 15.1), 65 (87%) females, and 10 (13%) males. WBC, CRP, RF, ESR, gammaglobulins, C4, C3 component of complement, cryoglobulins, ANA, anti-SS-A, and anti-SS-B antibodies were determined. The disease activity assessed with ESSDAI. Minor salivary gland biopsy (focus score and immunochemistry) was conducted. Results were analyzed with U Mann-Whitney (continuous variables) tests, correlations between quantitative variables assessed with the Spearman correlation coefficient with statistical significance set at p < 0.05. The approval of the Bioethics Committee was obtained.

RESULTS

Two subgroups I-RF(+) (61%) and II-RF(-) (39%) were established, with lower WBC (p = 0.012) and higher ESR (p = 0.016), gammaglobulin concentration (p = 0.007) in group I. Conjunctivitis sicca was more severe in group I. There was positive correlation between RF and lnANA (rho = 0.496), anti-SS-A, anti-SS-B antibodies (rho = 0.448; rho = 0.397 respectively). There was higher disease activity ESSDAI in group I than in group II (Me, 3.0 vs 2.0; p < 0.003). RF correlated negatively with WBC (rho = - 0.374). RF did not correlate with serum concentrations of BAFF, APRIL, CRP, and C3, C4 and with CD19+, CD3+, CD4+, CD 21+, and CD35+.

CONCLUSIONS

RF should be considered as a prognostic, but not diagnostic, factor in patients with pSS, as it is associated with more severe disease course (sicca eye symptoms, ESSDAI) and parameters (production of gammaglobulins, ANA, anti SS-A, anti-SS-B autoantibodies) indicating increased B cell activity.

T Cell-Dependent Affinity Maturation and Innate Immune Pathways Differentially Drive Autoreactive B Cell Responses in Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is characterized by the activation of B cells that produce anti-citrullinated protein antibodies (ACPAs) and rheumatoid factors (RFs), but the mechanisms by which tolerance is broken in these B cells remain incompletely understood. We undertook this study to investigate whether ACPA+ and RF+ B cells break tolerance through distinct molecular mechanisms.

METHODS

We developed antigen-tetramers to isolate ACPA+ and RF+ B cells and performed single-cell RNA sequencing on 2,349 B cells from 6 RA patients and 1 healthy donor to analyze their immunoglobulin repertoires and transcriptional programs. Prominent immunoglobulins were expressed as monoclonal antibodies and tested for autoantigen reactivity.

RESULTS

ACPA+ and RF+ B cells were enriched in the peripheral blood of RA patients relative to healthy controls. Characterization of patient-derived monoclonal antibodies confirmed ACPA and RF targeting of tetramer-specific B cells at both antigen-inexperienced and affinity-matured B cell stages. ACPA+ B cells used more class-switched isotypes and exhibited more somatic hypermutations relative to RF+ B cells, and these differences were accompanied by down-regulation of CD72 and up-regulation of genes that promote class-switching and T cell-dependent responses. In contrast, RF+ B cells expressed transcriptional programs that stimulate rapid memory reactivation through multiple innate immune pathways. Coexpression analysis revealed that ACPA+ and RF+ B cell-enriched genes belong to distinct transcriptional regulatory networks.

CONCLUSION

Our findings suggest that ACPA+ and RF+ B cells are imprinted with distinct transcriptional programs, which suggests that these autoantibodies associated with increased inflammation in RA arise from 2 different molecular mechanisms.

The lupus patient with positive rheumatoid factor

Background Patients with systemic lupus erythematosus (SLE) may form clusters with clinical manifestations and autoantibodies. Objective The objective of this report is to study whether SLE patients with positive rheumatoid factor (RF) have a special clinical and/or serological profile. Methods A retrospective study of 467 SLE patients seen at a single rheumatology unit was conducted. Epidemiological data (age, gender, age at disease onset, ethnic background and tobacco use), clinical data (malar rash, photosensitivity, oral ulcers, discoid lesions, serositis, glomerulonephritis, convulsions, psychosis, hemolytic anemia, leukopenia, lymphocytopenia, arthritis and hypothyroidism) and serological profile (anti-dsDNA, anti-Ro/SS-A, anti-La/SS-B, anti-RNP, anti-Sm, IgG aCL, IgM aCL, lupus anticoagulant, direct Coombs and RF) were collected. Patients with positive and negative RF were compared. Results RF was found in 24.9% of the sample. In univariate analysis, RF was positively associated with butterfly rash ( p = 0.04), anti-Ro ( p = 0.03), anti-Sm antibodies ( p = 0.01) and hypothyroidism ( p = 0.01) and negatively associated with glomerulonephritis ( p = 0.003). Logistic regression showed that only glomerulonephritis ( p = 0.03; OR = 0.45; 95% CI = 0.21-0.93) and anti-Ro ( p = 0.009; OR = 2.3; 95% CI = 1.24-4.57) were independent associations. Conclusion In our sample RF was associated with protection from glomerulonephritis and with higher prevalence of anti-Ro antibodies.

Rheumatoid arthritis: identifying and characterising polymorphisms using rat models

Rheumatoid arthritis is a chronic inflammatory joint disorder characterised by erosive inflammation of the articular cartilage and by destruction of the synovial joints. It is regulated by both genetic and environmental factors, and, currently, there is no preventative treatment or cure for this disease. Genome-wide association studies have identified ∼100 new loci associated with rheumatoid arthritis, in addition to the already known locus within the major histocompatibility complex II region. However, together, these loci account for only a modest fraction of the genetic variance associated with this disease and very little is known about the pathogenic roles of most of the risk loci identified. Here, we discuss how rat models of rheumatoid arthritis are being used to detect quantitative trait loci that regulate different arthritic traits by genetic linkage analysis and to positionally clone the underlying causative genes using congenic strains. By isolating specific loci on a fixed genetic background, congenic strains overcome the challenges of genetic heterogeneity and environmental interactions associated with human studies. Most importantly, congenic strains allow functional experimental studies be performed to investigate the pathological consequences of natural genetic polymorphisms, as illustrated by the discovery of several major disease genes that contribute to arthritis in rats. We discuss how these advances have provided new biological insights into arthritis in humans.

Lpr-induced systemic autoimmunity is unaffected by mast cell deficiency

The function of mast cells in allergic and organ-specific autoimmune responses is highly controversial. In the current study, we aimed to dissect the role of mast cells in systemic autoimmunity in the B6(lpr/lpr) mouse, a spontaneous model of systemic lupus erythematosus. B6(lpr/lpr) mice were interbred with C57Bl/6-Kit(W-sh/W-sh) (Wsh) mice, resulting in mast cell deficiency. The offspring from this cross (Lpr/Wsh mice) developed symptoms of lupus of the same severity as B6(lpr/lpr) mice. Loss of mast cells on the Lpr background did not alter autoantibody production, proteinuria, the composition of T and B cell populations or autoimmune pathology. Reduced c-Kit expression did drive expanded splenomegaly and impeded interleukin-4 production by CD4(+) cells, suggesting minor functions for mast cells. In general, we conclude that mast cell deficiency and c-Kit deficiency do not play a role in the pathogenesis of lupus in B6(lpr/lpr) mice.

Coherent somatic mutation in autoimmune disease

BACKGROUND

Many aspects of autoimmune disease are not well understood, including the specificities of autoimmune targets, and patterns of co-morbidity and cross-heritability across diseases. Prior work has provided evidence that somatic mutation caused by gene conversion and deletion at segmentally duplicated loci is relevant to several diseases. Simple tandem repeat (STR) sequence is highly mutable, both somatically and in the germ-line, and somatic STR mutations are observed under inflammation.

RESULTS

Protein-coding genes spanning STRs having markers of mutability, including germ-line variability, high total length, repeat count and/or repeat similarity, are evaluated in the context of autoimmunity. For the initiation of autoimmune disease, antigens whose autoantibodies are the first observed in a disease, termed primary autoantigens, are informative. Three primary autoantigens, thyroid peroxidase (TPO), phogrin (PTPRN2) and filaggrin (FLG), include STRs that are among the eleven longest STRs spanned by protein-coding genes. This association of primary autoantigens with long STR sequence is highly significant (p<3.0x10(-7)). Long STRs occur within twenty genes that are associated with sixteen common autoimmune diseases and atherosclerosis. The repeat within the TTC34 gene is an outlier in terms of length and a link with systemic lupus erythematosus is proposed.

CONCLUSIONS

The results support the hypothesis that many autoimmune diseases are triggered by immune responses to proteins whose DNA sequence mutates somatically in a coherent, consistent fashion. Other autoimmune diseases may be caused by coherent somatic mutations in immune cells. The coherent somatic mutation hypothesis has the potential to be a comprehensive explanation for the initiation of many autoimmune diseases.

Epstein-Barr virus in systemic autoimmune diseases

Systemic autoimmune diseases (SADs) are a group of connective tissue diseases with diverse, yet overlapping, symptoms and autoantibody development. The etiology behind SADs is not fully elucidated, but a number of genetic and environmental factors are known to influence the incidence of SADs. Recent findings link dysregulation of Epstein-Barr virus (EBV) with SAD development. EBV causes a persistent infection with a tight latency programme in memory B-cells, which enables evasion of the immune defence. A number of immune escape mechanisms and immune-modulating proteins have been described for EBV. These immune modulating functions make EBV a good candidate for initiation of autoimmune diseases and exacerbation of disease progression. This review focuses on systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and Sjögren's syndrome (SS) and sum up the existing data linking EBV with these diseases including elevated titres of EBV antibodies, reduced T-cell defence against EBV, and elevated EBV viral load. Together, these data suggest that uncontrolled EBV infection can develop diverse autoreactivities in genetic susceptible individuals with different manifestations depending on the genetic background and the site of reactivation.

Rheumatoid factor B cell memory leads to rapid, switched antibody-forming cell responses

B cells are critical in the initiation and maintenance of lupus. Autoreactive B cells clonally expand, isotype switch, and mutate--properties associated with memory B cells (MBCs), which are typically generated via germinal centers. The development and functions of autoreactive MBCs in lupus are poorly understood. Moreover, mounting evidence implicates the extrafollicular (EF) response in the generation of switched and mutated autoantibodies that are driven by BCR and TLR corecognition, raising the question of whether MBCs are generated in this context. In this study, we investigated autoreactive MBC generation associated with this type of response. We transferred B cells from AM14 site-directed BCR transgenic mice into nontransgenic normal recipients and elicited an EF response with anti-chromatin Ab, as in prior studies. By following the fate of the stimulated cells at late time points, we found that AM14 B cells persisted at increased frequency for up to 7 wk. Furthermore, these cells had divided in response to Ag but were subsequently quiescent, with a subset expressing the memory marker CD73. These cells engendered rapid, isotype-switched secondary plasmablast responses upon restimulation. Both memory and rapid secondary responses required T cell help to develop, emphasizing the need for T-B collaboration for long-term self-reactivity. Thus, using this model system, we show that the EF response generated persistent and functional MBCs that share some, but not all, of the characteristics of traditional MBCs. Such cells could play a role in chronic or flaring autoimmune disease.

Antibody clustering helps refine lupus prognosis

OBJECTIVE

Our aim was to investigate a possible association between patterns of anti-dsDNA antibody isotypes (IgG, IgM, and IgA), rheumatoid factor (RF) isotypes (IgG, IgM, IgA), and IgG anti-C reactive protein (CRP) and systemic lupus erythematosus (SLE) disease activity (SLEDAI).

METHODS

Our study group included 98 patients, 86 women and 12 men, with a mean SLEDAI score of 7.9 +/- 4.1. We divided the patients into 4 groups by the serum anti-dsDNA antibody isotype intensity level.

RESULTS

We found that patients in group 1 (IgG > IgM, 42 patients) had a statistically significantly higher SLEDAI score than group 2 (IgG < IgM, 13 patients) (10.57 +/- 4.62 versus 5.6 +/- 4, P = 0.0012), group 3 (IgG = IgM, 8 patients) (10.57 +/- 4.62 versus 6.2 +/- 1.98, P = 0.04), and group 4 (none, 35 patients) (10.57 +/- 4.62 versus 6 +/- 1.5, P = 0.0001). SLE patients with IgG RF or IgM RF isotype present had a significantly higher SLEDAI score compared with those without IgG RF or IgM RF (10.57 +/- 4.8 versus 7.6 +/- 4.1, P = 0.03, 10.6 +/- 5 versus 7.6 +/- 3.9, P = 0.046). The presence of IgA RF isotype was not associated with a higher SLEDAI score. IgG anti-CRP did not correlate differentially with SLEDAI scores.

CONCLUSIONS

A combination of high-titer IgG anti-dsDNA with a positive RF of IgM isotype may serve as a marker for more active SLE.

Sites and stages of autoreactive B cell activation and regulation

B cells are essential for the development and pathogenesis of both systemic and organ-specific autoimmune diseases. Autoreactive B cells are typically thought of as sources of autoantibody, but their most important pathogenetic roles may be to present autoantigens to T cells and to secrete proinflammatory cytokines. A rate-limiting step in the genesis of autoimmunity then is the activation of autoreactive B cells. Here, mechanisms are discussed that normally prevent such activation and how they break down during disease. Integrating classic work with recent insights, emphasis is placed on efforts to pinpoint the precursor cells for autoantibody-secreting cells and the unique stimuli and pathways by which they are activated.

Anti-chromatin antibodies drive in vivo antigen-specific activation and somatic hypermutation of rheumatoid factor B cells at extrafollicular sites

A dominant type of spontaneous autoreactive B cell activation in murine lupus is the extrafollicular generation of plasmablasts. The factors governing such activation have been difficult to identify due to the stochastic onset and chronic nature of the response. Thus, the ability to induce a similar autoreactive B cell response with a known autoantigen in vivo would be a powerful tool in deciphering how autoimmune responses are initiated. We report here the establishment and characterization of a system to initiate autoreactive extrafollicular B cell responses, using IgG anti-chromatin antibodies, that closely mirrors the spontaneous response. We demonstrate that exogenously administered anti-chromatin antibody, presumably by forming immune complexes with released nuclear material, drives activation of rheumatoid factor B cells in AM14 Tg mice. Anti-chromatin elicits autoreactive B cell activation and development into antibody-forming cells at the T zone/red pulp border. Plasmablast generation occurs equally in BALB/c, MRL/+ and MRL/lpr mice, indicating that an autoimmune-prone genetic background is not required for the induced response. Importantly, infused IgG anti-chromatin induces somatic hypermutation in the absence of a GC response, thus proving the extrafollicular somatic hypermutation pathway. This system provides a window on the initiation of an autoantibody response and reveals authentic initiators of it.

Clinical criteria for systemic lupus erythematosus precede diagnosis, and associated autoantibodies are present before clinical symptoms

OBJECTIVE

Specific events that occur during the development of systemic lupus erythematosus (SLE) can be quite variable among individual patients. The aim of this study was to identify patterns that distinguish early clinical events in SLE and to assess whether the presence of associated autoantibodies precedes the fulfillment of clinical criteria.

METHODS

Through a retrospective chart review of military medical records, 130 patients who met the American College of Rheumatology (ACR) criteria for the classification of SLE were identified. The initial time at which each criterion was fulfilled was recorded. Autoantibody analysis was performed on serum samples, using enzyme-linked immunosorbent assays or immunofluorescence.

RESULTS

The clinical features that were observed earliest were discoid rash and seizures, which developed a mean 1.74 and 1.70 years, respectively, before the diagnosis of SLE; however, arthritis was the criterion that was most commonly observed before diagnosis. The presence of IgG rheumatoid factor (IgG-RF) preceded the development of arthritis in 15 (94%) of the 16 patients who were positive for IgG-RF and in whom arthritis developed (Z = 10.2, P < 0.0001). Analogously, IgM-RF appeared before the development of arthritis in 13 (76%) of 17 patients. Anti-double-stranded DNA antibodies were associated with renal disease and appeared before evidence of nephritis in most patients (92%) (Z = 13.3, P < 0.0001). An analysis of the appearance of autoantibodies compared with the appearance of clinical criteria not associated with them revealed no significant temporal relationship.

CONCLUSION

Symptoms associated with the ACR criteria for classification of SLE are commonly present before the diagnosis of SLE, and development of organ-associated autoantibodies generally precedes the appearance of their associated clinical features.

Type I interferon production by tertiary lymphoid tissue developing in response to 2,6,10,14-tetramethyl-pentadecane (pristane)

Lymphoid neogenesis is associated with antibody-mediated autoimmune diseases such as Sjogren's syndrome and rheumatoid arthritis. Although systemic lupus erythematosus is the prototypical B-cell-mediated autoimmune disease, the role of lymphoid neogenesis in its pathogenesis is unknown. Intraperitoneal injection of 2,6,10,14-tetramethyl-pentadecane (TMPD, pristane) or mineral oil causes lipogranuloma formation in mice, but only TMPD-treated mice develop lupus. We report that lipogranulomas are a form of lymphoid neogenesis. Immunoperoxidase staining of lipogranulomas revealed B cells, CD4(+) T cells, and dendritic cells and in some cases organization into T- and B-cell zones. Lipogranulomas also expressed the lymphoid chemokines CCL21, CCL19, CXCL13, CXCL12, and CCL22. Expression of the type I interferon (IFN-I)-inducible genes Mx1, IRF7, IP-10, and ISG-15 was greatly increased in TMPD- versus mineral oil-induced lipogranulomas. Dendritic cells from TMPD lipogranulomas underwent activation/maturation with high CD86 and interleukin-12 expression. Magnetic bead depletion of dendritic cells markedly diminished IFN-inducible gene (Mx1) expression. We conclude that TMPD-induced lupus is associated with the formation of ectopic lymphoid tissue containing activated dendritic cells producing IFN-I and interleukin-12. In view of the increased IFN-I production in systemic lupus erythematosus, these studies suggest that IFN-I from ectopic lymphoid tissue could play a role in the pathogenesis of experimental lupus in mice.

A medical bioinformatics approach for metabolic disorders: Biomedical data prediction, modeling, and systematic analysis

During the past century, studies of metabolic disorders have focused research efforts to improve clinical diagnosis and management, to illuminate metabolic mechanisms, and to find effective treatments. The availability of human genome sequences and transcriptomic, proteomic, and metabolomic data provides us with a challenging opportunity to develop computational approaches for systematic analysis of metabolic disorders. In this paper, we present a strategy of bioinformatics analysis to exploit the current data available both on genomic and metabolic levels and integrate these at novel levels of understanding of metabolic disorders. PathAligner is applied to predict biomedical data based on a given disorder. A case study on urea cycle disorders is demonstrated. A Petri net model is constructed to estimate the regulation both on genomic and metabolic levels. We also analyze the transcription factors, signaling pathways and associated disorders to interpret the occurrence and regulation of the urea cycle.

AVAILABILITY

PathAligner's metabolic disorder analyzer is available at http://bibiserv.techfak.uni-bielefeld.de/pathaligner/pathaligner_MDA.html. Supplementary materials are available at http://www.techfak.uni-bielefeld.de/~mchen/metabolic_disorders.

Association of anti-nucleoprotein autoantibodies with upregulation of Type I interferon-inducible gene transcripts and dendritic cell maturation in systemic lupus erythematosus

Lupus patients selectively produce autoantibodies against nucleoproteins. Since the RNA/DNA components of these autoantigens are endogenous TLR ligands capable of stimulating Type I interferon (IFN-I) production, we asked whether autoantibodies against the ribonucleoproteins Sm/RNP and Ro60 and double-stranded DNA are associated with high levels of IFN-I. IFN-I levels were increased in SLE (n = 88) vs. other autoimmune diseases (n = 82) and controls (n = 57) (P < 0.0001) and were associated positively with autoantibodies against Sm/RNP, Ro60/La, and dsDNA but negatively with anti-phospholipid. Low numbers of circulating plasmacytoid and myeloid dendritic cells also were associated with these autoantibodies. The IFN-I and dendritic cell abnormalities correlated with disease severity and were not therapy-related. These findings suggest that immunostimulatory nucleic acid components of autoantigens may act as endogenous adjuvants by promoting IFN-I production and dendritic cell maturation, helping to explain the high prevalence of autoantibodies against nucleoprotein antigens in SLE.

Autoantibody explosion in systemic lupus erythematosus: more than 100 different antibodies found in SLE patients

OBJECTIVE

Description of the various autoantibodies that can be detected in patients with systemic lupus erythematosus (SLE).

METHODS

A literature review, using the terms "autoantibody" and "systemic lupus erythematosus", was conducted to search for articles on autoantibodies in SLE, their target antigens, association with disease activity, or other clinical associations.

RESULTS

One hundred sixteen autoantibodies were described in SLE patients. These include autoantibodies that target nuclear antigens, cytoplasmic antigens, cell membrane antigens, phospholipid-associated antigens, blood cells, endothelial cells, and nervous system antigens, plasma proteins, matrix proteins, and miscellaneous antigens. The target of autoantibody, the autoantigen properties, autoantibody frequencies in SLE, as well as clinical associations, and correlation with disease activity are described for all 116 autoantibodies.

CONCLUSIONS

SLE is the autoimmune disease with the largest number of detectable autoantibodies. Their production could be antigen-driven, the result of polyclonal B cell activation, impaired apoptotic pathways, or the outcome of idiotypic network dysregulation.

Stratification of pedigrees multiplex for systemic lupus erythematosus and for self-reported rheumatoid arthritis detects a systemic lupus erythematosus susceptibility gene (SLER1) at 5p15.3

OBJECTIVE

Arthritis is a common manifestation in systemic lupus erythematosus (SLE), appearing in approximately 85% of patients. Often, the polyarthritis at presentation of SLE cannot be distinguished from rheumatoid arthritis (RA) by physical examination or history. Indeed, physicians initially tell many SLE patients that they have RA (one source of "self-reported RA"), only to have SLE established later. In addition, RA aggregates in families with an SLE proband. We predicted that pedigrees multiplex for both SLE and for self-reported RA would better isolate particular genetic effects. If this proved to be true, we would then use the increased genetic homogeneity to more easily reveal genetic linkage.

METHODS

From a collection of 160 pedigrees multiplex for SLE, we selected 36 pedigrees that also contained >or=2 members with self-reported RA (19 pedigrees were African American, 14 were European American, and 3 were of other ethnic origin). Data from a genome scan of 307 microsatellite markers were evaluated for SLE linkage by contemporary genetic epidemiologic techniques.

RESULTS

The most significant evidence of linkage to SLE was obtained at 5p15.3 in the European American pedigrees by both parametric (logarithm of odds [LOD] score 6.2, P = 9.3 x 10(-8)) and nonparametric (LOD score 6.9, P = 1.7 x 10(-8)) methods. The best-fitting model for this putative SLE gene in this region was a recessive gene with a population frequency of 5% and with 50% penetrance in females and 15% penetrance in males at virtually 100% homogeneity.

CONCLUSION

For a genetically complex disease phenotype, an unusually powerful linkage has been found with SLE at 5p15.3 in European American pedigrees multiplex for SLE and for self-reported RA. This result predicts the presence of a gene at the top of chromosome 5 in this subset of patients that is important for the pathogenesis of SLE.

Comparative study of different enzyme immunoassays for measurement of IgM and IgA rheumatoid factors

OBJECTIVE

To compare the value of various IgM and IgA rheumatoid factor (RF) tests for the diagnosis of rheumatoid arthritis (RA).

METHODS

Firstly, the latex test, one global assay (for IgM, IgA, and IgG RF), six IgM, and four IgA RF assays were compared in a particularly challenging situation-that is, with 67 patients with RA, many of whom were latex negative, and 91 non-RA controls, many of whom were latex positive. More detailed evaluation followed with three IgM RF tests (two commercially available kits and one assay developed in our laboratory) and two IgA RF tests (one commercially available and one from our laboratory) in two more representative samples of rheumatological patients (146 RA and 75 non-RA controls).

RESULTS

Diagnostic performance differed considerably between the assays. For IgM RF detection the highest sensitivity (88%) was obtained with the Diamedix kit (specificity 67%) and for IgA RF with the Inova kit (sensitivity 65%, specificity 88%). Combining one IgM and one IgA RF test improved diagnostic performance when both tests were in agreement, but at the cost of yielding 15-27% of discrepant results which did not help in ruling RA in or out. Mean concentration values differed significantly among IgM RF tests, and in most cases concentrations were not correlated.

CONCLUSIONS

Available tests for IgM RF isotype vary in accuracy, and none is uniformly better than all the others. For IgA RF isotype, the Inova kit appears to be the best. Quantitative results cannot be compared across tests. Combination of one IgM and one IgA RF test may improve diagnostic accuracy.