The liver and muscle secreted HFE2-protein maintains central nervous system blood vessel integrity

Liver failure causes breakdown of the Blood CNS Barrier (BCB) leading to damages of the Central-Nervous-System (CNS), however the mechanisms whereby the liver influences BCB-integrity remain elusive. One possibility is that the liver secretes an as-yet to be identified molecule(s) that circulate in the serum to directly promote BCB-integrity. To study BCB-integrity, we developed light-sheet imaging for three-dimensional analysis. We show that liver- or muscle-specific knockout of Hfe2/Rgmc induces BCB-breakdown, leading to accumulation of toxic-blood-derived fibrinogen in the brain, lower cortical neuron numbers, and behavioral deficits in mice. Soluble HFE2 competes with its homologue RGMa for binding to Neogenin, thereby blocking RGMa-induced downregulation of PDGF-B and Claudin-5 in endothelial cells, triggering BCB-disruption. HFE2 administration in female mice with experimental autoimmune encephalomyelitis, a model for multiple sclerosis, prevented paralysis and immune cell infiltration by inhibiting RGMa-mediated BCB alteration. This study has implications for the pathogenesis and potential treatment of diseases associated with BCB-dysfunction.

Serum S100A8/A9 and MMP-9 levels are elevated in systemic lupus erythematosus patients with cognitive impairment

Objective

Cognitive impairment (CI) is one of the most common manifestations of Neuropsychiatric Systemic Lupus Erythematosus (NPSLE). Despite its frequency, we have a limited understanding of the underlying immune mechanisms, resulting in a lack of pathways to target. This study aims to bridge this gap by investigating differences in serum analyte levels in SLE patients based on their cognitive performance, independently from the attribution to SLE, and exploring the potential for various serum analytes to differentiate between SLE patients with and without CI.

Methods

Two hundred ninety individuals aged 18-65 years who met the 2019-EULAR/ACR classification criteria for SLE were included. Cognitive function was measured utilizing the adapted ACR-Neuropsychological Battery (ACR-NB). CI was defined as a z-score of ≤-1.5 in two or more domains. The serum levels of nine analytes were measured using ELISA. The data were randomly partitioned into a training (70%) and a test (30%) sets. Differences in the analyte levels between patients with and without CI were determined; and their ability to discriminate CI from non-CI was evaluated.

Results

Of 290 patients, 40% (n=116) had CI. Serum levels of S100A8/A9 and MMP-9, were significantly higher in patients with CI (p=0.006 and p=0.036, respectively). For most domains of the ACR-NB, patients with CI had higher S100A8/A9 serum levels than those without. Similarly, S100A8/A9 had a negative relationship with multiple CI tests and the highest AUC (0.74, 95%CI: 0.66-0.88) to differentiate between patients with and without CI.

Conclusion

In this large cohort of well-characterized SLE patients, serum S100A8/A9 and MMP-9 were elevated in patients with CI. S100A8/A9 had the greatest discriminatory ability in differentiating between patients with and without CI.

Circulating neutrophil extracellular trap remnants as a biomarker to predict outcomes in lupus nephritis

OBJECTIVE

To determine if the serum levels of neutrophil extracellular trap (NET) remnants (Elastase-DNA and HMGB1-DNA complexes) at the time of a lupus nephritis (LN) flare predict renal outcomes in the following 24 months.

METHODS

This was a retrospective study performed in prospectively followed cohorts. The study included two cohorts: an exploratory cohort to assess the association between NET remnant levels and the presence of active LN, and a separate LN cohort to determine the utility of NET remnants to predict renal outcomes over the subsequent 24 months.

RESULTS

Ninety-two individuals were included in the exploratory cohort (49 active systemic lupus erythematosus (SLE), 23 inactive SLE and 20 healthy controls (HC)). NET remnants were significantly higher in patients with SLE patients compared with HC (p<0.0001 for both complexes) and those with active LN (36%) had significantly higher levels of NET remnants compared with active SLE without LN (Elastase-DNA: p=0.03; HMGB1-DNA: p=0.02). The LN cohort included 109 active LN patients. Patients with proliferative LN had significantly higher levels of NET remnants than non-proliferative LN (Elastase-DNA: p<0.0001; HMGB1-DNA: p=0.0003). Patients with higher baseline levels of NET remnants had higher odds of not achieving complete remission (Elastase-DNA: OR 2.34, p=0.007; HMGB1-DNA: OR 2.61, p=0.009) and of progressing to severe renal impairment (Elastase-DNA: OR 2.84, p=0.006; HMGB1-DNA: OR 2.04, p=0.02) at 24 months after the flare.

CONCLUSIONS

Elastase-DNA and HMGB1-DNA complexes predict renal outcomes, suggesting they could be used to identify patients requiring more aggressive therapy at flare onset.

Systemic lupus erythematosus phenotypes formed from machine learning with a specific focus on cognitive impairment

OBJECTIVE

To phenotype SLE based on symptom burden (disease damage, system involvement and patient reported outcomes), with a specific focus on objective and subjective cognitive function.

METHODS

SLE patients ages 18-65 years underwent objective cognitive assessment using the ACR Neuropsychological Battery (ACR-NB) and data were collected on demographic and clinical variables, disease burden/activity, health-related quality of life (HRQoL), depression, anxiety, fatigue and perceived cognitive deficits. Similarity network fusion (SNF) was used to identify patient subtypes. Differences between the subtypes were evaluated using Kruskal-Wallis and χ2 tests.

RESULTS

Of the 238 patients, 90% were female, with a mean age of 41 years (s.d. 12) and a disease duration of 14 years (s.d. 10) at the study visit. The SNF analysis defined two subtypes (A and B) with distinct patterns in objective and subjective cognitive function, disease burden/damage, HRQoL, anxiety and depression. Subtype A performed worst on all significantly different tests of objective cognitive function (P < 0.03) compared with subtype B. Subtype A also had greater levels of subjective cognitive function (P < 0.001), disease burden/damage (P < 0.04), HRQoL (P < 0.001) and psychiatric measures (P < 0.001) compared with subtype B.

CONCLUSION

This study demonstrates the complexity of cognitive impairment (CI) in SLE and that individual, multifactorial phenotypes exist. Those with greater disease burden, from SLE-specific factors or other factors associated with chronic conditions, report poorer cognitive functioning and perform worse on objective cognitive measures. By exploring different ways of phenotyping SLE we may better define CI in SLE. Ultimately this will aid our understanding of personalized CI trajectories and identification of appropriate treatments.

Genetics of longitudinal kidney function in children and adults with systemic lupus erythematosus

OBJECTIVES

Genome-wide association studies (GWAS) have identified loci associated with estimated glomerular filtration rate (eGFR). Few LN risk loci have been identified to date. We tested the association of SLE and eGFR polygenic risk scores (PRS) with repeated eGFR measures from children and adults with SLE.

METHODS

Patients from two tertiary care lupus clinics that met ≥4 ACR and/or SLICC criteria for SLE were genotyped on the Illumina MEGA or Omni1-Quad arrays. PRSs were calculated for SLE and eGFR, using published weighted GWA-significant alleles. eGFR was calculated using the CKD-EPI and Schwartz equations. We tested the effect of eGFR- and SLE-PRSs on eGFR mean and variance, adjusting for age at diagnosis, sex, ancestry, follow-up time, and clinical event flags.

RESULTS

We included 1158 SLE patients (37% biopsy-confirmed LN) with 36 733 eGFR measures over a median of 7.6 years (IQR: 3.9-15.3). LN was associated with lower within-person mean eGFR [LN: 93.8 (s.d. 26.4) vs non-LN: 101.6 (s.d. 17.7) mL/min per 1.73 m2; P < 0.0001] and higher variance [LN median: 157.0 (IQR: 89.5, 268.9) vs non-LN median: 84.9 (IQR: 46.9, 138.2) (mL/min per 1.73 m2)2; P < 0.0001]. Increasing SLE-PRSs were associated with lower mean eGFR and greater variance, while increasing eGFR-PRS was associated with increased eGFR mean and variance.

CONCLUSION

We observed significant associations between SLE and eGFR PRSs and repeated eGFR measurements, in a large cohort of children and adults with SLE. Longitudinal eGFR may serve as a powerful alternative outcome to LN categories for discovery of LN risk loci.

Genetics of osteonecrosis in children and adults with systemic lupus erythematosus

OBJECTIVES

Genetics plays an important role in SLE risk, as well as osteonecrosis (ON), a significant and often debilitating complication of SLE. We aimed to identify genetic risk loci for ON in people with childhood-onset (cSLE) and adult-onset (aSLE) SLE.

METHODS

We enrolled participants from two tertiary care centres who met classification criteria for SLE. Participants had prospectively collected clinical data and were genotyped on a multiethnic array. Un-genotyped single nucleotide polymorphisms (SNPs) were imputed, and ancestry was inferred using principal components (PCs). Our outcome was symptomatic ON confirmed by imaging. We completed time-to-ON and logistic regression of ON genome-wide association studies (GWASs) with covariates for sex, age of SLE diagnosis, five PCs for ancestry, corticosteroid use and selected SLE manifestations. We conducted separate analyses for cSLE and aSLE and meta-analysed results using inverse-variance weighting. Genome-wide significance was P < 5 × 10-8.

RESULTS

The study included 940 participants with SLE, 87% female and 56% with cSLE. ON was present in 7.6% (n = 71). Median age of SLE diagnosis was 16.9 years (interquartile range [IQR]: 13.5, 29.3), with median follow-up of 8.0 years (IQR: 4.2, 15.7). Meta-GWAS of cSLE and aSLE time-to-ON of 4 431 911 SNPs identified a significant Chr.2 SNP, rs34118383 (minor allele frequency = 0.18), intronic to WIPF1 (hazard ratio = 3.2 [95% CI: 2.2, 4.8]; P = 1.0 × 10-8).

CONCLUSION

We identified an intronic WIPF1 variant associated with a 3.2 times increased hazard for ON (95% CI: 2.2, 4.8; P = 1.0 × 10-8) during SLE follow-up, independent of corticosteroid exposure. The effect of the SNP on time-to-ON was similar in cSLE and aSLE. This novel discovery represents a potential ON risk locus. Our results warrant replication.

Centrally acting ACE inhibitor (cACEi) and angiotensin receptor blocker (cARB) use and cognitive dysfunction in patients with SLE

OBJECTIVE

Cognitive dysfunction (CD) is detectable in approximately 40% of patients with SLE. Despite this high prevalence, there are no approved pharmacological treatment options for this detrimental condition. Preliminary murine studies show potential for targeting microglial activation as a treatment of SLE-CD, which may be ameliorated with centrally acting ACE inhibitor (cACEi) and angiotensin receptor blocker (cARB) use. The aim of this study is to determine if there is an association of cACEi/cARB use with cognitive function in a human SLE cohort.

METHODS

The American College of Rheumatology neuropsychological battery was administered to patients with consecutive SLE at a single academic health centre at baseline, 6 and 12 months. Scores were compared with sex-matched and age-matched control subjects. Clinical and demographic data were gathered at each visit. The primary outcome was CD defined as dysfunction in two or more cognitive domains. The primary predictor was a total cumulative dose of cACEi/cARB in milligrams per kilogram, recorded as an equivalent ramipril dose. Odds of CD with respect to cACEi/cARB use were determined through generalised linear mixed modelling.

RESULTS

A total of 300 patients, representing 676 visits, completed this study. One hundred sixteen (39%) met the criteria for CD. Fifty-three participants (18%) were treated with a cACEi or cARB. Mean cumulative dose was 236 mg/kg (calculated as equivalent ramipril dose). Cumulative cACEi/cARB dose was not protective against SLE-CD. Caucasian ethnicity, current employment status and azathioprine cumulative dose were each associated with reduced odds of SLE-CD. Increasing Fatigue Severity Scale score was associated with increased odds of CD.

CONCLUSIONS

In a single-centre SLE cohort, cACEi/cARB use was not associated with absence of CD. Many important confounders may have influenced the results of this retrospective study. A randomised trial is required to accurately determine if cACEi/cARB is a potential treatment for SLE-CD.

In-person versus virtual administration of the American College of Radiology gold standard cognitive battery in systemic lupus erythematosus: Are they interchangeable?

OBJECTIVE

During the COVID-19 pandemic, many research studies were adapted, including our longitudinal study examining cognitive impairment (CI) in systemic lupus erythematosus (SLE). Cognitive testing was switched from in-person to virtual. This analysis aimed to determine if the administration method (in-person vs. virtual) of the ACR-neuropsychological battery (ACR-NB) affected participant cognitive performance and classification.

METHODS

Data from our multi-visit, SLE CI study included demographic, clinical, and psychiatric characteristics, and the modified ACR-NB. Three analyses were undertaken for cognitive performance: (1) all visits, (2) non-CI group visits only and (3) intra-individual comparisons. A retrospective preferences questionnaire was given to participants who completed the ACR-NB both in-person and virtually.

RESULTS

We analysed 328 SLE participants who had 801 visits (696 in-person and 105 virtual). Demographic, clinical, and psychiatric characteristics were comparable except for ethnicity, anxiety and disease-related damage. Across all three comparisons, six tests were consistently statistically significantly different. CI classification changed in 11/71 (15%) participants. 45% of participants preferred the virtual administration method and 33% preferred in-person.

CONCLUSIONS

Of the 19 tests in the ACR-NB, we identified one or more problems with eight (42%) tests when moving from in-person to virtual administration. As the use of virtual cognitive testing will likely increase, these issues need to be addressed - potentially by validating a virtual version of the ACR-NB. Until then, caution must be taken when directly comparing virtual to in-person test results. If future studies use a mixed administration approach, this should be accounted for during analysis.

Interferon and interferon-induced cytokines as markers of impending clinical progression in ANA+ individuals without a systemic autoimmune rheumatic disease diagnosis

BACKGROUND

Elevated levels of interferons (IFNs) are a characteristic feature of systemic autoimmune rheumatic diseases (SARDs) and may be useful in predicting impending symptomatic progression in anti-nuclear antibody-positive (ANA⁺) individuals lacking a SARD diagnosis. Typically, these are measured by their effect on gene expression in the blood, which has limited their utility in clinical settings. Here, we assessed whether the measurement of serum IFN-α or selected IFN-induced cytokines accurately mirrors IFN-induced gene expression in ANA⁺ individuals and investigated their utility as biomarkers of clinical progression.

METHODS

A total of 280 subjects were studied, including 50 ANA^- healthy controls, 160 ANA⁺ individuals without a SARD diagnosis (96 asymptomatic, 64 with undifferentiated connective tissue disease), and 70 SARD patients. IFN-induced gene expression was measured by nanoString and cytokine levels by ELISA or Simoa. ANA⁺ individuals lacking a SARD diagnosis who had the new onset of SARD criteria over the subsequent 2 years were defined as progressors.

RESULTS

Measurement of IFN-α levels by high-sensitivity ELISA or Simoa correlated much better with IFN-induced gene expression than measurement of CXCL-10 or Galectin-9 levels. Despite this, high CXCL-10 and Galectin-9 levels were better predictors of subsequent progression in ANA⁺ individuals than measures of IFN-α or IFN-induced gene expression with the optimal combination of predictive cytokines (CXCL-10 and IFN-α as measured by ELISA), resulting in a specificity and positive predictive value of 100%.

CONCLUSION

Easily performed ELISA assays for CXCL-10 and IFN-α can be used to predict ANA⁺ individuals at high risk of imminent symptomatic progression.

Identification and Validation of a Urinary Biomarker Panel to Accurately Diagnose and Predict Response to Therapy in Lupus Nephritis

Background

We have previously shown that 15 urinary biomarkers (of 129 tested by Luminex), discriminate between active Lupus Nephritis (ALN) and non-LN patients. The aim of this study was to evaluate the ability of these 15 previously-identified urinary biomarkers to predict treatment responses to conventional therapy, and for the most predictive of these biomarkers to validate their utility to identify ALN patients in an independent prospectively-acquired lupus cohort.

Methods

Our study had a 3-stage approach. In stage 1, we used Luminex to examine whether our previously identified urinary biomarkers at the time of the renal flare ( ± 3 months) or 12 ± 3 months after treatment of biopsy-proven ALN could predict treatment responses. In stage 2, a larger prospectively-acquired cross-sectional cohort was used to further validate the utility of the most predictive urinary biomarkers (identified in stage 1) to detect ALN patients. In this 2^nd stage, cut-offs with the best operating characteristics to detect ALN patients were produced for each biomarker and different combinations and/or numbers of elevated biomarkers needed to accurately identify ALN patients were analyzed. In stage 3, we aimed to further corroborate the sensitivity of the cut-offs created in stage 2 to detect ALN patients in a biopsy-proven ALN cohort who had a urine sample collection within 3 months of their biopsy.

Results

Twenty-one patients were included in stage 1. Twelve (57.1%), 4 (19.1%), and 5 (23.8%) patients had a complete (CR), partial (PR) and no (NR) remission at 24 ± 3 months, respectively. The percentage decrease following 12 ± 3 months of treatment for Adiponectin, MCP-1, sVCAM-1, PF4, IL-15 and vWF was significantly higher in patients with CR in comparison to those with PR/NR. In stage 2, a total of 247 SLE patients were included, of which 24 (9.7%) had ALN, 79 (31.9%) had LN in remission (RLN) and 144 (58.3%) were non-LN (NLN) patients. Based on the combinations of biomarkers with the best operating characteristics we propose “rule out” and “rule in” ALN criteria. In stage 3, 53 biopsy-proven ALN patients were included, 35 with proliferative LN and 18 with non-proliferative ALN, demonstrating that our “rule in ALN” criteria operate better in detecting active proliferative than non-proliferative classes.

Conclusions

Our results provide further evidence to support the role of Adiponectin, MCP-1, sVCAM-1 and PF4 in the detection of proliferative ALN cases. We further show the clinical utility of measuring multiple rather than a single biomarker and we propose novel “rule in” and “rule out” criteria for the detection of proliferative ALN with excellent operating characteristics.

A highly virulent variant of HIV-1 circulating in the Netherlands

We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log₁₀ increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV-CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences-is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

Insight into intraindividual variability across neuropsychological tests and its association with cognitive dysfunction in patients with lupus

Objective

Dispersion, or variability in an individual’s performance across multiple tasks at a single assessment visit, has been associated with cognitive dysfunction (CD) in many neurodegenerative and neurodevelopmental disorders. We aimed to compute a dispersion score using neuropsychological battery (NB) tests and determine its association with CD in patients with SLE.

Methods

CD was defined as a z-score of ≤−1.5 on ≥2 domains of the NB. To compute a type of dispersion score known as the intraindividual SD (ISD), the SD of age-adjusted and sex-adjusted z-scores was calculated for each visit in each patient. To estimate the association between ISD and cognitive status (CD and non-CD), we used multilevel logistic regression, adjusting for clinically important covariates.

Results

A total of 301 adult patients with SLE completed the NB at baseline, 187 of whom were reassessed at 6 months and 189 at 12 months. CD was observed in 35.2% of patients at baseline, 27.8% at 6 months and 28.0% at 12 months. Prior to covariate adjustment, the mean ISD for non-CD was 1.10±0.31 compared with 1.50±0.70 for CD. After adjusting for ethnicity, education, employment, socioeconomic status and anxiety/depression, there was a statistically significant association between ISD and CD (OR for one-unit increase in ISD: 13.56, 95% CI 4.80 to 38.31; OR for 1/10th-unit increase in ISD: 1.30, 95% CI 1.17 to 1.44). Findings were valid across multiple sensitivity analyses.

Conclusion

This is the first study to show that patients with SLE who were classified as having CD by the NB had more variability across the NB tests (ie, higher ISD score) compared with those who were not classified as having CD.

Serological abnormalities that predict progression to systemic autoimmune rheumatic diseases in antinuclear antibody positive individuals

OBJECTIVE

We investigated the auto-antibody (auto-Ab) profiles in anti-nuclear antibody-positive (ANA+) individuals lacking Systemic Autoimmune Rheumatic Disease (SARD) and early SARD patients, to determine the key differences between these groups and identify factors that are associated with an increased risk of symptomatic progression within the next two years in ANA+ individuals.

METHODS

Using custom antigen (Ag) microarrays, 144 IgM and IgG auto-Abs were surveyed in 84 asymptomatic and 123 symptomatic (48 undifferentiated connective tissue disease (UCTD) and 75 SARD patients) ANA+ individuals. Auto-Ab were compared in ANA+ individuals lacking a SARD diagnosis with ≥ 2 years follow-up (n = 52), including all those who demonstrated progression (n = 14) during this period, with changes over time assessed in a representative subset.

RESULTS

We show that ANA+ individuals have auto-Ab to many self-Ag that are not being captured by current screening techniques and very high levels of these auto-Abs are predominantly restricted to early SARD patients, with SLE patients displaying reactivity to many more auto-Ags than the other groups. In general, the symptoms that developed in progressors mirrored those seen in SARD patients with similar patterns of auto-Ab. Only anti-Ro52 Abs were found to predict progression (positive predictive value 46%, negative predictive value 89%). Surprisingly, over 2 years follow-up the levels of auto-Ab remained remarkably stable regardless of whether individuals progressed or not.

CONCLUSION

Our findings strongly argue that development of assays with an expanded set of auto-Ags and enhanced dynamic range would improve the diagnostic and prognostic ability of auto-Ab testing.

The baseline interferon signature predicts disease severity over the subsequent 5 years in systemic lupus erythematosus

Objectives

Type I interferons (IFNs) play an important role in the pathophysiology of systemic lupus erythematosus (SLE). While cross-sectional data suggest an association between IFN-induced gene expression and SLE disease activity, interest in this as a biomarker of flare has been tempered by a lack of fluctuation with disease activity in the majority of patients. This led us to question whether IFN-induced gene expression might instead be a biomarker of overall disease severity, with patients with high levels spending more time in an active disease state.

Methods

Levels of five interferon-responsive genes were measured in the whole peripheral blood at baseline visit for 137 SLE patients subsequently followed for 5 years. Log transformed values were summed to yield a composite IFN5 score, and the correlation with various disease outcomes examined. Receiver operator characteristic analyses were performed for outcomes of interest. Kaplan-Meier curves were generated to compare the proportion of flare-free patients with high and low IFN5 scores over time.

Results

The baseline IFN5 score was positively correlated with the adjusted mean SLE disease activity index-2000, number of flares, adjusted mean prednisone dose, and number of new immunosuppressive medications over the subsequent 5 years. Optimal cut-offs for the IFN5 score were determined using Youden’s index and predicted more severe outcomes with 57–67% accuracy. A high baseline IFN5 level was associated with a significantly increased risk of subsequent flare.

Conclusions

Measurement of the type I IFN signature is a useful tool for predicting the subsequent disease activity course.

Relationship Between Genetic Risk and Age of Diagnosis in Systemic Lupus Erythematosus

OBJECTIVE

Specific risk alleles for childhood-onset systemic lupus erythematosus SLE (cSLE) vs adult-onset SLE (aSLE) patients have not been identified. The aims of this study were to determine if there is an association (1) between non-HLA-related genetic risk score (GRS) and age of SLE diagnosis, and (2) between HLA-related GRS and age of SLE diagnosis.

METHODS

Genomic DNA was obtained from 2001 multiethnic patients and genotyped using the Immunochip. Following quality control, genetic risk counting (GRCS), weighted (GRWS), standardized counting (GRSCS), and standardized weighted (GRSWS) scores were calculated based on independent single-nucleotide polymorphisms from validated SLE loci. Scores were analyzed in a regression model and adjusted by sex and ancestral population.

RESULTS

The analyzed cohort consisted of 1540 patients: 1351 females and 189 males (675 cSLE and 865 aSLE). There were significant negative associations between all non-HLA GRS and age of SLE diagnosis: P = 0.011 and r² = 0.175 for GRWS; P = 0.008 and r² = 0.178 for GRSCS; P = 0.002 and r² = 0.176 for GRSWS (higher GRS correlated with lower age of diagnosis.) All HLA GRS showed significant positive associations with age of diagnosis: P = 0.049 and r² = 0.176 for GRCS; P = 0.022 and r² = 0.176 for GRWS; P = 0.022 and r² = 0.176 for GRSCS; P = 0.011 and r² = 0.177 for GRSWS (higher GRS correlated with higher age of diagnosis).

CONCLUSION

Our data suggest that there is a linear relationship between genetic risk and age of SLE diagnosis and that HLA and non-HLA GRS are associated with age of diagnosis in opposite directions.

Fatigue severity in anti-nuclear antibody-positive individuals does not correlate with pro-inflammatory cytokine levels or predict imminent progression to symptomatic disease

Background

Fatigue is a common symptom of systemic autoimmune rheumatic disease (SARD). Patients with SARD have a protracted pre-clinical phase during which progressive immunologic derangements occur culminating in disease. In this study, we sought to determine when fatigue develops and whether its presence correlates with inflammatory factors or predicts disease progression.

Methods

Anti-nuclear antibody (ANA)-negative healthy controls (HCs) and ANA-positive participants with no criteria, at least one clinical criteria (undifferentiated connective tissue disease, UCTD), or meeting SARD classification criteria were recruited. Fatigue was assessed using a modified version of the FACIT-F questionnaire and the presence of fibromyalgia determined using a questionnaire based on the modified 2010 ACR criteria. Peripheral blood expression of five IFN-induced genes was quantified by NanoString and the levels of IL-1β, IL-6, or TNF-α by ELISA.

Results

Fatigue was as prevalent and severe in individuals lacking SARD criteria as it was in UCTD and SARD. Overall, ~ 1/3 of ANA⁺ subjects met fibromyalgia criteria, with no differences between sub-groups. Although fatigue was more severe in these individuals, those lacking fibromyalgia remained significantly more fatigued than ANA⁻ HC. However, even in these subjects, fatigue correlated with the widespread pain index and symptom severity scores on the fibromyalgia questionnaire. Fatigue was not associated with elevated cytokine levels in any of the ANA⁺ sub-groups and did not predict imminent disease progression.

Conclusions

Fatigue is common in ANA⁺ individuals lacking sufficient criteria for a SARD diagnosis, correlates with fibromyalgia-related symptoms, and is not associated with inflammation or predictive of disease progression.

Apoptotic cell-induced AhR activity is required for immunological tolerance and suppression of systemic lupus erythematosus in mice and humans

The transcription factor AhR modulates immunity at multiple levels. Here we report phagocytes exposed to apoptotic cells exhibited rapid activation of AhR, which drove production of interleukin 10. Activation of AhR was dependent on interactions between apoptotic-cell DNA and the pattern-recognition receptor TLR9 that was required for prevention of immune responses to DNA and histones in vivo. Moreover, disease progression in murine systemic lupus erythematosus (SLE) correlated with strength of the AhR signal, and disease course could be altered by modulation of AhR activity. Deletion of AhR in the myeloid lineage caused systemic autoimmunity in mice and an increased AhR transcriptional signature correlated with disease in patients with SLE. Thus, AhR activity induced by apoptotic cell phagocytes maintains peripheral tolerance.

Apoptotic cell induced, TLR9-dependent AhR activity is a critical driver of tolerance induction and suppression of lupus

The Aryl hydrocarbon receptor (AhR) can potently modulate immunity at multiple levels, but its mechanistic role in immune regulation is still being elucidated. Here we show phagocytes exposed to apoptotic cells exhibit rapid activation of AhR driving IL-10 that antagonizes inflammatory cytokine production. AhR activation was dependent on apoptotic cell DNA-TLR9 interactions and reactive oxygen species (ROS) production in phagocytes that promoted nuclear accumulation and transcriptional activity. In vivo, apoptotic cell-induced AhR signals in myeloid cells were required for prevention of inflammatory innate and adaptive immunity against DNA and histones. Moreover, disease progression in lupus correlated with AhR signal strength, and disease course could be reduced or exacerbated by modulation of AhR activity. Finally, we observed myeloid specific deletion of AhR in mice resulted in systemic autoimmunity, and in SLE patients an increased AhR transcriptional signature correlated with disease. Thus, our findings suggest AhR activity influenced by apoptotic cell death is a key mechanism in maintenance of peripheral tolerance reducing inflammation and thereby retarding systemic autoimmune disease progression.

Apoptotic cell driven ROS burst drives AhR dependent immunologic tolerance and suppression of lupus

Tissue-resident macrophages (MΦ) are crucial in driving tolerance and preventing systemic autoimmunity. We have previously shown that exposure to apoptotic cells triggers a regulatory circuit dependent on IL-10 production in resident MΦ. However, key molecular mechanisms driving the regulatory response to apoptosis are not clear. RNA transcriptome analysis of MΦs after exposure to apoptotic cells identified strong transcript association with the aryl hydrocarbon receptor (AhR) signaling pathway, an association that was confirmed by phenotypic and biochemical analysis. When AhR activity was blocked, apoptotic cells induced an alteration in the mRNA signature enhancing proinflammatory effector expression. Functional analysis revealed that the DNA from apoptotic cells activated AhR in a reactive oxygen species (ROS) dependent mechanism and AhR is required for IL-10 production. Consequently, inhibition or deletion of AhR signals fundamentally altered immune responses to apoptotic cells in vivo resulting in proinflammatory cytokine production, increased effector T cell responses, and failure of long-term tolerance to apoptotic cell-associated antigens. Surprisingly, mice lacking AhR developed progressive systemic autoimmunity characterized by excessive MΦ and lymphocyte activation and renal pathology. Similarly, SLE-prone mice treated with AhR antagonist exhibited poor survival, while agonist treatment ablated disease pathology. Finally, an AhR transcriptional signature was significantly associated with active SLE flare in SLE patients. Thus, the data demonstrates the AhR pathway is a key molecular circuit responsible for apoptotic cell driven tolerance and suppression of inflammatory autoimmunity.

Presence of an interferon signature in individuals who are anti-nuclear antibody positive lacking a systemic autoimmune rheumatic disease diagnosis

Background

Elevated levels of type I interferons (IFNs) are a characteristic feature of the systemic autoimmune rheumatic diseases (SARDs) and are thought to play an important pathogenic role. However, it is unknown whether these elevations are seen in anti-nuclear antibody–positive (ANA⁺) individuals who lack sufficient criteria for a SARD diagnosis. We examined IFN-induced gene expression in asymptomatic ANA⁺ individuals and patients with undifferentiated connective tissue disease (UCTD) to address this question.

Methods

Healthy ANA⁻ control subjects and ANA⁺ titre (≥1:160 by immunofluorescence) participants meeting no criteria, meeting at least one criterion (UCTD) or meeting SARD classification criteria were recruited. Whole peripheral blood IFN-induced and BAFF gene expression were quantified using NanoString technology. The normalized levels of five IFN-induced genes were summed to produce an IFN5 score.

Results

The mean IFN5 scores were increased in all ANA⁺ participant subsets as compared with healthy control subjects. We found that 36.8% of asymptomatic ANA⁺ and 50% of UCTD participants had IFN5 scores >2 SD above the mean for healthy control subjects. In all ANA⁺ subsets, the IFN5 score correlated with the presence of anti-Ro/La antibodies. In the asymptomatic ANA⁺ subset, this score also correlated with the ANA titre, whereas in the other ANA⁺ subsets, it correlated with the number of different ANA specificities. Development of new SARD criteria was seen in individuals with normal and high IFN5 scores.

Conclusions

An IFN signature is seen in a significant proportion of ANA⁺ individuals and appears to be associated with ANA titre and type of autoantibodies, rather than with the presence or development of clinical SARD symptoms.

A discrete cluster of urinary biomarkers discriminates between active systemic lupus erythematosus patients with and without glomerulonephritis

Background

Management of lupus nephritis (LN) would be greatly aided by the discovery of biomarkers that accurately reflect changes in disease activity. Here, we used a proteomics approach to identify potential urinary biomarkers associated with LN.

Methods

Urine was obtained from 60 LN patients with paired renal biopsies, 25 active non-LN SLE patients, and 24 healthy controls. Using Luminex, 128 analytes were quantified and normalized to urinary creatinine levels. Data were analyzed by linear modeling and non-parametric statistics, with corrections for multiple comparisons. A second cohort of 33 active LN, 16 active non-LN, and 30 remission LN SLE patients was used to validate the results.

Results

Forty-four analytes were identified that were significantly increased in active LN as compared to active non-LN. This included a number of unique proteins (e.g., TIMP-1, PAI-1, PF4, vWF, and IL-15) as well as known candidate LN biomarkers (e.g., adiponectin, sVCAM-1, and IL-6), that differed markedly (>4-fold) between active LN and non-LN, all of which were confirmed in the validation cohort and normalized in remission LN patients. These proteins demonstrated an enhanced ability to discriminate between active LN and non-LN patients over several previously reported biomarkers. Ten proteins were found to significantly correlate with the activity score on renal biopsy, eight of which strongly discriminated between active proliferative and non-proliferative/chronic renal lesions.

Conclusions

A number of promising urinary biomarkers that correlate with the presence of active renal disease and/or renal biopsy changes were identified and appear to outperform many of the existing proposed biomarkers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1120-0) contains supplementary material, which is available to authorized users.

Cancer Cells Hijack PRC2 to Modify Multiple Cytokine Pathways

Polycomb Repressive Complex 2 (PRC2) is an epigenetic regulator induced in many cancers. It is thought to drive tumorigenesis by repressing division, stemness, and/or developmental regulators. Cancers evade immune detection, and diverse immune regulators are perturbed in different tumors. It is unclear how such cell-specific effects are coordinated. Here, we show a profound and cancer-selective role for PRC2 in repressing multiple cytokine pathways. We find that PRC2 represses hundreds of IFNγ stimulated genes (ISGs), cytokines and cytokine receptors. This target repertoire is significantly broadened in cancer vs non-cancer cells, and is distinct in different cancer types. PRC2 is therefore a higher order regulator of the immune program in cancer cells. Inhibiting PRC2 with either RNAi or EZH2 inhibitors activates cytokine/cytokine receptor promoters marked with bivalent H3K27me3/H3K4me3 chromatin, and augments responsiveness to diverse immune signals. PRC2 inhibition rescues immune gene induction even in the absence of SWI/SNF, a tumor suppressor defective in ~20% of human cancers. This novel PRC2 function in tumor cells could profoundly impact the mechanism of action and efficacy of EZH2 inhibitors in cancer treatment.

Anti-dsDNA and Antichromatin Antibody Isotypes in Serologically Active Clinically Quiescent Systemic Lupus Erythematosus

OBJECTIVE

Serologically active clinically quiescent (SACQ) patients with systemic lupus erythematosus (SLE) are clinically quiescent despite serologic activity. Since studies suggest that antichromatin antibodies are more sensitive than anti-dsDNA antibodies in detecting active SLE, and that immunoglobulin (Ig) G, in particular complement-fixing subclasses, may be more pathogenic than IgM, we investigated the levels of anti-dsDNA and antichromatin isotypes in SACQ patients as compared to non-SACQ patients with SLE.

METHODS

Levels of IgM, IgA, IgG, and IgG1-4 antichromatin and anti-dsDNA were measured by ELISA. SACQ was defined as ≥ 2 years with the SLE Disease Activity Index 2000 (SLEDAI-2K) at 2 or 4 from serologic activity, during which patients could be taking antimalarials, but not corticosteroids or immunosuppressives. Unselected non-SACQ patients with SLE were used as comparators. SACQ patient serum samples were further stratified based on subsequent development of flare, defined as clinical SLEDAI-2K ≥ 1 and/or treatment initiation. Nonparametric statistics were used, and generalized estimating equations were applied to account for multiple samples in the same patient.

RESULTS

SACQ patients' complement-fixing antichromatin and anti-dsDNA IgG subclasses were significantly higher than those of non-SACQ patients. When the sample drawn latest in a SACQ period was analyzed, there was no difference between antichromatin or anti-dsDNA isotype or IgG subclass levels between patients who flared and those who remained SACQ, nor were consistent trends seen when samples were examined during SACQ and flare in the same patient.

CONCLUSION

The SACQ phenotype does not arise from a lack of pathogenic anti-dsDNA and/or antichromatin autoantibodies. Neither increases in antichromatin nor anti-dsDNA isotype or IgG subclass levels were predictive of or coincident with flare in SACQ patients.

Anti-nucleosome antibodies outperform traditional biomarkers as longitudinal indicators of disease activity in systemic lupus erythematosus

OBJECTIVE

The aim of this study was to determine whether anti-nucleosome antibodies function as activity-specific biomarkers in SLE.

METHODS

Fifty-one patients were recruited and followed prospectively with periodic clinical and biochemical assessments over a 14-month period. Disease activity was determined by the SLEDAI-2K. Anti-nucleosome antibody levels were measured by an ELISA and its utility as an activity-specific biomarker as compared with that of anti-dsDNA antibodies and C3 was assessed both at baseline and in longitudinal analysis.

RESULTS

Anti-nucleosome antibodies were significantly elevated in SLE patients vs controls and showed a moderate positive correlation with disease activity. The utility of anti-nucleosome antibodies in identifying patients with active disease in a cross-sectional analysis was comparable to that of anti-dsDNA antibodies and C3. Analysis of variance demonstrated that the level of anti-nucleosome antibodies and C3 varied significantly with changes in disease activity over time. Changes in clinical state were not mirrored by changes in anti-dsDNA antibodies. In time-dependent analysis, anti-nucleosome antibodies showed a better fit over time than anti-dsDNA antibodies and C3. In pairwise comparisons, C3 and anti-nucleosome antibodies outperformed other models, including the conventional pairing of C3 and anti-dsDNA antibodies, however, no biomarker alone or as a group accurately predicted impending remissions or exacerbations.

CONCLUSION

Anti-nucleosome antibodies demonstrate greater fidelity as a biomarker for changes in SLE disease activity than traditional biomarkers, supporting the routine monitoring of this antibody in clinical practice.

Evaluation of clinical outcomes and renal vascular pathology among patients with lupus

BACKGROUND AND OBJECTIVES

The objective of this study was to determine the clinical significance of renal vascular lesions in lupus nephritis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Renal vascular lesions defined as thrombotic microangiopathy, lupus vasculopathy, uncomplicated vascular immune deposits, and arterial sclerosis were evaluated in relation to renal and vascular morbidity and overall mortality.

RESULTS

Biopsies from 161 patients revealed thrombotic microangiopathy (13), lupus vasculopathy (5), and arterial sclerosis (93). No renal vascular lesions were found in 24.8% of patients. At the time of biopsy, arterial sclerosis or lupus vasculopathy patients were older (arterial sclerosis=37.9±13.0 and lupus vasculopathy=44.4±8.9 versus controls=33.1±8.9 years, P<0.05), and the mean arterial pressure was higher in all groups compared with controls. Nephritis subtype, activity indices, and proteinuria were similar between groups, estimated GFR was lower in arterial sclerosis (70.5±33.3 versus 84.5±26.6 ml/min per 1.73 m(2), P=0.03), and chronicity index (thrombotic microangiopathy=3.5, lupus vasculopathy=4.5, and arterial sclerosis=2.5) was higher in all renal vascular lesions subgroups versus controls (1.0, P<0.05). In 133 patients with similar follow-up, the association between renal vascular lesions and vascular events was significant (Fisher exact test, P=0.002) and remained so after multivariate analysis (exact conditional scores test, P=0.04), where the difference between arterial sclerosis and uncomplicated vascular immune deposits was most noticeable (odds ratio [95% confidence interval]=8.35[0.98, 83.12], P=0.05). The associations between renal vascular lesions, renal outcomes, and death were not significant, likely because of insufficient power.

CONCLUSIONS

Renal vascular lesions are common in SLE patients with nephritis and may be associated with arterial vascular events.

Molecular markers of injury in kidney biopsy specimens of patients with lupus nephritis

Prediction of prognosis in patients who have lupus nephritis is inadequate, limiting individualization of potentially toxic therapy. Advances in tissue molecular techniques offer new approaches to study mechanisms underlying kidney injury, and add to prognostic information gleaned from biopsy specimens. Analysis of mRNA expression in formalin-fixed, paraffin-embedded renal biopsy specimens is limited by both quantity and quality of RNA, requiring RNA pre-amplification, which can introduce bias. Accordingly, we developed a new technique for RNA extraction from human kidney formalin fixed paraffin embedded biopsy specimens, and used Taqman low-density arrays Applied Biosystems, Carlsbad, CA to simultaneously measure 48 mRNAs in duplicate, in a single biopsy. We extracted mRNA from more than 150 blocks to determine the quantity and vintage of biopsy tissue suitable for analysis using this protocol. We then used Taqman low-density arrays to identify suitable housekeeping genes in lupus nephritis. Finally, we measured expression of 48 mRNA transcripts in archived lupus biopsy specimens (n = 54). We identified that the mRNA levels of three transcripts (MMP7, EGF, COL1A1) relate to pathological indices of kidney injury and kidney function at the time of biopsy; these were associated with parallel changes in expression of these proteins. This new method for measurement of kidney biopsy mRNA expression has enabled us to identify tissue biomarkers of kidney damage and function, and potentially can increase the information yielded from diagnostic kidney biopsy specimens to improve tailoring of therapy.

Genetic loci on New Zealand black chromosome 1 lead to increased generation of T follicular helper and TH17 cells (47.23)

Genetic loci on NZB c1 lead to antinuclear antibody (Ab) production and glomerulonephritis (GN). Using subcongenic lines, we found at least 5 genetic loci within a 35-106cM interval modulate disease. Notably, mice with a 70-100cM interval (c1(70-100cM)) develop high titre anti-dsDNA Ab, increased numbers of large germinal centers and severe GN a characteristic feature of lupus-prone mice with abnormalities of T follicular helper (TFH) and Th17 cells. In this study we determined whether variations in disease severity in c1 subcongenic mice are associated with differences in these subsets. The proportion of splenic TFH cells was significantly increased in c1(70-100) mice. Splenocytes from all c1 congenic mouse strains demonstrated increased production of IL-21 and IL-17 following anti-CD3/CD28 crosslinking which was greatest in c1(70-100) mice. The majority of IL-21 producing cells were TFH, many of which also secreted IFN-γ, but not IL-17. Immunization of 8-wk-old pre-autoimmune mice with ovalbumin (OVA) led to increased generation of TFH and Th17 cells in c1 (70-100) mice. This appeared to result in part from altered T cell function, as adoptively transferred OVA-specific TCR transgenic c1(70-100) T cells and naïve c1(70-100) T cells cultured in-vitro, demonstrated enhanced differentiation to TFH and IL-17-producing cells. Thus, genetic loci on NZB c1 promote differentiation of T cells to TFH and Th17 cells and this capacity correlates with the severity of disease.

Persistent proteinuria and dyslipidemia increase the risk of progressive chronic kidney disease in lupus erythematosus

Advances in immunotherapy have improved survival of patients with systemic lupus erythematosus who now face an increasing burden of chronic diseases including that of the kidney. As systemic inflammation is also thought to contribute directly to the progression of chronic kidney disease (CKD), we assessed this risk in patients with lupus, with and without a diagnosis of nephritis, and also identified modifiable risk factors. Accordingly, we enrolled 631 patients (predominantly Caucasian), of whom 504 were diagnosed with lupus within the first year and followed them an average of 11 years. Despite the presence of a chronic inflammatory disease, the rate of decline in renal function of 238 patients without nephritis was similar to that described for non-lupus patient cohorts. Progressive loss of kidney function developed exclusively in patients with lupus nephritis who had persistent proteinuria and dyslipidemia, although only six required dialysis or transplantation. The mortality rate was 16% with half of the deaths attributable to sepsis or cancer. Thus, despite the presence of a systemic inflammatory disease, the risk of progressive CKD in this lupus cohort was relatively low in the absence of nephritis. Hence, as in idiopathic glomerular disease, persistent proteinuria and dyslipidemia (modifiable risks) are the major factors for CKD progression in lupus patients with renal involvement.

Occupational and environmental exposures and risk of systemic lupus erythematosus: silica, sunlight, solvents

OBJECTIVES

We examined occupational and non-occupational exposures in relation to risk of SLE in a case-control study conducted through the Canadian Network for Improved Outcomes in SLE (CaNIOS).

METHODS

SLE cases (n = 258) were recruited from 11 rheumatology centres across Canada. Controls (without SLE, n = 263) were randomly selected from phone number listings and matched to cases by age, sex and area of residence. Data were collected using a structured telephone interview.

RESULTS

An association was seen with outdoor work in the 12 months preceding diagnosis [odds ratio (OR) 2.0; 95% CI 1.1, 3.8]; effect modification by sun reaction was suggested, with the strongest effect among people who reported reacting to midday sun with a blistering sunburn or a rash (OR 7.9; 95% CI 0.97, 64.7). Relatively strong but imprecise associations were seen with work as an artist working with paints, dyes or developing film (OR 3.9; 95% CI 1.3, 12.3) and work that included applying nail polish or nail applications (OR 10.2; 95% CI 1.3, 81.5). Patients were more likely than controls to report participation in pottery or ceramics work as a leisure activity, with an increased risk among individuals with a total frequency of at least 26 days (OR 2.1; 95% CI 1.1, 3.9). Analyses of potential respirable silica exposures suggested an exposure-response gradient (OR 1.0, 1.4. and 2.1 for zero, one and two or more sources of exposure, respectively; trend test P < 0.01).

CONCLUSIONS

This study supports the role of specific occupational and non-occupational exposures in the development of SLE.

B cell activating factor (BAFF) and T cells cooperate to breach B cell tolerance in lupus-prone New Zealand Black (NZB) mice

The presence of autoantibodies in New Zealand Black (NZB) mice suggests a B cell tolerance defect however the nature of this defect is unknown. To determine whether defects in B cell anergy contribute to the autoimmune phenotype in NZB mice, soluble hen egg lysozyme (sHEL) and anti-HEL Ig transgenes were bred onto the NZB background to generate double transgenic (dTg) mice. NZB dTg mice had elevated levels of anti-HEL antibodies, despite apparently normal B cell functional anergy in-vitro. NZB dTg B cells also demonstrated increased survival and abnormal entry into the follicular compartment following transfer into sHEL mice. Since this process is dependent on BAFF, BAFF serum and mRNA levels were assessed and were found to be significantly elevated in NZB dTg mice. Treatment of NZB sHEL recipient mice with TACI-Ig reduced NZB dTg B cell survival following adoptive transfer, confirming the role of BAFF in this process. Although NZB mice had modestly elevated BAFF, the enhanced NZB B cell survival response appeared to result from an altered response to BAFF. In contrast, T cell blockade had a minimal effect on B cell survival, but inhibited anti-HEL antibody production. The findings suggest that the modest BAFF elevations in NZB mice are sufficient to perturb B cell tolerance, particularly when acting in concert with B cell functional abnormalities and T cell help.

The use of micronutrient supplements is not associated with better quality of life and disease activity in Canadian patients with systemic lupus erythematosus

OBJECTIVE

Associations between the use of micronutrient supplements (MS) and disease activity, quality of life (QOL), and healthcare resource utilization were studied in a Canadian population of patients with systemic lupus erythematosus (SLE).

METHODS

QOL was assessed by the Medical Outcomes Study 36-item Short Form. Healthcare resource utilization and disease activity/damage were determined.

RESULTS

Of the 259 subjects studied, 53% were MS users and 34% used only calcium/vitamin D. MS users had a higher Systemic Lupus International Collaborating Clinics score and utilized more healthcare resources. Disease activity and QOL were similar between MS users and nonusers.

CONCLUSION

MS are frequently used by patients with SLE and are not associated with concomitant benefit on QOL. MS users utilized more healthcare resources.

A B cell intrinsic defect initiates autoimmunity in New Zealand Black chromosome 13 congenic mice (49.21)

Introgression of a New Zealand Black (NZB) chromosome 13 (c13) interval onto a lupus-resistant C57BL/6 (B6) background (denoted, B6.NZBc13) is sufficient to produce many of the hallmarks of lupus. To characterize the immune defects leading to these abnormalities observed in B6.NZBc13 mice, bone marrow (BM) chimeras and BCR transgenic mice were produced. In BM chimeras, transfer of B6.NZBc13 BM cells was sufficient to transfer autoimmunity. Interestingly, in mixed BM chimeras the abnormal T and B cell activation as well as DC expansion was observed in both B6 and B6.NZBc13 derived cells; but with greater B cell activation in B6.NZBc13 derived cells. When an anti-HEL Ig transgene was crossed onto the congenic background disease was abrogated and the abnormal cellular phenotypes normalized. Although tolerance was retained in anti-HEL Ig/soluble HEL double transgenic mice, increased numbers of 'edited' cells were seen in the periphery. B cell function studies revealed altered phosphorylation of signaling molecules downstream of the BCR. These findings indicate the presence of a BM-cell intrinsic defect on NZB c13 that can be localized to a B cell defect, which is necessary to initiate the autoimmune phenotype in B6.NZBc13 mice.

The prevalence and accuracy of self-reported history of 11 autoimmune diseases

OBJECTIVE

To determine the prevalence and confirmation rate of autoimmune diseases reported by relatives of patients with lupus and controls.

METHODS

Medical histories were obtained by self-report from 626 first-degree relatives of lupus patients and 267 population controls.

RESULTS

Of 178 reports of an autoimmune disease, 44% were confirmed by medical records; excluding those whose medical records were unavailable, the confirmation rate was 76%. The prevalence of at least one confirmed autoimmune disease was 12% in lupus relatives and 2% in controls.

CONCLUSION

Methods to improve the reliability of self-reported autoimmune disease history could enhance population and clinic-based research.

Reduced proportions of natural killer T cells are present in the relatives of lupus patients and are associated with autoimmunity

Introduction

Systemic lupus erythematosus is a genetically complex disease. Currently, the precise allelic polymorphisms associated with this condition remain largely unidentified. In part this reflects the fact that multiple genes, each having a relatively minor effect, act in concert to produce disease. Given this complexity, analysis of subclinical phenotypes may aid in the identification of susceptibility alleles. Here, we used flow cytometry to investigate whether some of the immune abnormalities that are seen in the peripheral blood lymphocyte population of lupus patients are seen in their first-degree relatives.

Methods

Peripheral blood mononuclear cells were isolated from the subjects, stained with fluorochrome-conjugated monoclonal antibodies to identify various cellular subsets, and analyzed by flow cytometry.

Results

We found reduced proportions of natural killer (NK)T cells among 367 first-degree relatives of lupus patients as compared with 102 control individuals. There were also slightly increased proportions of memory B and T cells, suggesting increased chronic low-grade activation of the immune system in first-degree relatives. However, only the deficiency of NKT cells was associated with a positive anti-nuclear antibody test and clinical autoimmune disease in family members. There was a significant association between mean parental, sibling, and proband values for the proportion of NKT cells, suggesting that this is a heritable trait.

Conclusions

The findings suggest that analysis of cellular phenotypes may enhance the ability to detect subclinical lupus and that genetically determined altered immunoregulation by NKT cells predisposes first-degree relatives of lupus patients to the development of autoimmunity.

Lack of association between the interferon-alpha signature and longitudinal changes in disease activity in systemic lupus erythematosus

OBJECTIVE

To study the longitudinal expression of interferon (IFN)-inducible genes in systemic lupus erythematosus (SLE) and determine their suitability as disease biomarkers.

METHODS

RNA was isolated from the peripheral blood of 94 patients with SLE and 11 controls and reverse transcribed into cDNA. The expression levels of five IFN-responsive genes (LY6E, OAS1, IFIT1, ISG15 and MX1) were determined by quantitative PCR, normalised to GAPDH and summed to generate a global IFN score. Patients were followed longitudinally for a period of 3-12 months, and the association between disease activity, as measured by the SLE disease activity index (SLEDAI-2K), and other clinical and laboratory variables was examined.

RESULTS

The expression of all five IFN-responsive genes was significantly higher in patients with SLE than in controls. The expression of LY6E, OAS1, IFIT1 and the global IFN score was associated with high disease activity. The global IFN score was also associated with active renal disease, a decreased C3, and the presence of anti-dsDNA or anti-RNA binding protein antibodies at a single point in time. However, there was a poor correlation between changes in this score and changes in disease activity, C3 or anti-dsDNA antibody levels in patients followed longitudinally. In most patients the levels of IFN-induced gene expression remained relatively stable over 3-12 months despite marked changes in disease activity. Nevertheless, in patients with low/moderate disease activity, those with high IFN scores had a more recent history of sustained high disease activity.

CONCLUSION

The findings indicate that IFN-induced gene expression has limited clinical utility as a biomarker of acute changes in disease activity.

Immunization with an apoptotic cell-binding protein recapitulates the nephritis and sequential autoantibody emergence of systemic lupus erythematosus

The initial events predisposing to loss of tolerance in patients with systemic lupus erythematosus (SLE) are largely unknown, as are the events that precipitate the transition from preclinical to overt disease. We hypothesized that induction of murine SLE would require tipping the balance between tolerance and immunity in two ways: 1) an immunogen that could take advantage of apoptotic cells as a scaffold for epitope spread, and 2) an immune activator that would generate a strong and persistent T cell response to the inciting immunogen. We show that immunization of C57BL/6 and BALB/c mice with human beta(2)-glycoprotein I, an apoptotic cell-binding protein, in the presence of LPS induces a long-lived, potent response to beta(2)-glycoprotein I that results in epitope spread to multiple SLE autoantigens. SLE-specific autoantibodies emerged in a sequential manner that recapitulated the order seen in human SLE. Moreover, immunized mice developed overt glomerulonephritis closely resembling human lupus nephritis.

Lymphocytic infiltration and immune activation in metallothionein promoter-exendin-4 (MT-Exendin) transgenic mice

Glucagon-like peptide 1 (GLP-1) exhibits considerable potential for the treatment of type 2 diabetes because of its effects on stimulation of insulin secretion and the inhibition of gastric emptying, appetite, and glucagon secretion. However, native GLP-1 undergoes rapid enzymatic inactivation, prompting development of long-acting degradation-resistant GLP-1 receptor agonists such as exendin-4 (Ex-4). To study the consequences of sustained exposure to Ex-4, we generated metallothionein promoter-exendin-4 (MT-Exendin) mice that continuously express a proexendin-4 transgene in multiple murine tissues. We now report that MT-Exendin mice develop extensive tissue lymphocytic infiltration with increased numbers of CD4(+) and CD8a(+) cells in the liver and/or kidney and increased numbers of B220(+) cells present in the pancreas and liver. MT-Exendin mice generate antibodies directed against Ex-4, exendin NH(2)-terminal peptide (ENTP), and proexendin-4 as well as antibodies that cross-react with native GLP-1. Furthermore, lymphocytes isolated from MT-Exendin mice proliferate in response to proexendin-4 but not after exposure to Ex-4 or ENTP. These findings demonstrate that expression of a proexendin-4 transgene may be associated with activation of humoral and cellular immune responses in mice.

Aberrant IgM Signaling Promotes Survival of Transitional T1 B Cells and Prevents Tolerance Induction in Lupus-Prone New Zealand Black Mice

New Zealand Black (NZB) mice develop a lupus-like syndrome. Although the precise immune defects leading to autoantibody production in these mice have not been characterized, they possess a number of immunologic abnormalities suggesting that B cell tolerance may be defective. In the bone marrow, immature self-reactive B cells that have failed to edit their receptors undergo apoptosis as a consequence of Ig receptor engagement. Splenic transitional T1 B cells are recent bone marrow emigrants that retain these signaling properties, ensuring that B cells recognizing self-Ags expressed only in the periphery are deleted from the naive B cell repertoire. In this study we report that this mechanism of tolerance is defective in NZB mice. We show that NZB T1 B cells are resistant to apoptosis after IgM cross-linking in vitro. Although extensive IgM cross-linking usually leads to deletion of T1 B cells, in NZB T1 B cells we found that it prevents mitochondrial membrane damage, inhibits activation of caspase-3, and promotes cell survival. Increased survival of NZB T1 B cells was associated with aberrant up-regulation of Bcl-2 after Ig receptor engagement. We also show that there is a markedly increased proportion of NZB T1 B cells that express elevated levels of Bcl-2 in vivo and provide evidence that up-regulation of Bcl-2 follows encounter with self-Ag in vivo. Thus, we propose that aberrant cell signaling in NZB T1 B cells leads to the survival of autoreactive B cells, which predisposes NZB mice to the development of autoimmunity.

T-cell tolerance induction is normal in the (NZB x NZW)F1 murine model of systemic lupus erythematosus

The (New Zealand black (NZB) x New Zealand white (NZW))F1 (NZB/W) mouse strain spontaneously develops an autoimmune disease characterized by anti-dsDNA antibody production and glomerulonephritis. Although evidence suggests that production of pathogenic autoantibodies is T-cell dependent, the immunological defects that lead to activation of these autoreactive T cells are unknown. In particular, it has not been resolved whether autoreactive T cells become activated in these mice because of a generalized defect in T-cell tolerance induction. Previous work has demonstrated that thymic and peripheral tolerance to strongly deleting antigens are intact in NZB/W mice. In this study we investigate whether these mice possess a more subtle T-cell tolerance defect. To this end, we have produced NZB/W mice carrying a transgene encoding beef insulin (BI) which is expressed at levels close to the threshold for T-cell tolerance induction. In BALB/c mice this transgene produces a profound but incomplete state of BI-specific T-cell tolerance, mediated predominantly by clonal anergy. Comparison of BI-specific tolerance in NZB/W, major histocompatibility complex (MHC)-matched (BALB/c x NZW)F1, and BALB/c BI-transgenic mice clearly demonstrates that T-cell tolerance induction is normal in NZB/W mice. The data suggest that the loss of T-cell tolerance that ultimately supports nephritogenic autoantibody production in NZB/W mice does not result from a generalized defect in T-cell tolerance, and by extension likely results from aberrant activation of specific autoreactive T cells.

Autoimmunity Develops in Lupus-Prone NZB Mice Despite Normal T Cell Tolerance

NZB mice spontaneously develop an autoimmune disease characterized by production of anti-RBC, -lymphocyte, and -ssDNA Abs. Evidence suggests that the NZB mouse strain has all of the immunologic defects required to produce lupus nephritis but lacks an MHC locus that allows pathogenic anti-dsDNA Ab production. The capacity to produce diverse autoantibodies in these mice raises the possibility that they possess a generalized defect in self-tolerance. To determine whether this defect is found within the T cell subset, we backcrossed a transgene encoding bovine insulin (BI) onto the NZB background. In nonautoimmune BALB/c mice, the BI transgene induces a profound but incomplete state of T cell tolerance mediated predominantly by clonal anergy. Comparison of tolerance in NZB and BALB/c BI-transgenic mice clearly demonstrated that NZB T cells were at least as tolerant to BI as BALB/c T cells. NZB BI-transgenic mice did not spontaneously produce anti-BI Abs, and following antigenic challenge, BI-specific Ab production was comparably reduced in both BI-transgenic NZB and BALB/c mice. Further, in vitro BI-specific T cell proliferation and cytokine secretion were appropriately decreased for primed lymph node and splenic T cells derived from NZB BI-transgenic relative to their nontransgenic counterparts. These data indicate that a generalized T cell tolerance defect does not underlie the autoimmune disease in NZB mice. Instead, we propose that the T cell-dependent production of pathogenic IgG autoantibodies in these mice arises from abnormal activation of T cells in the setting of normal but incomplete tolerance.

Autoimmunity develops in lupus-prone NZB mice despite normal T cell tolerance

NZB mice spontaneously develop an autoimmune disease characterized by production of anti-RBC, -lymphocyte, and -ssDNA Abs. Evidence suggests that the NZB mouse strain has all of the immunologic defects required to produce lupus nephritis but lacks an MHC locus that allows pathogenic anti-dsDNA Ab production. The capacity to produce diverse autoantibodies in these mice raises the possibility that they possess a generalized defect in self-tolerance. To determine whether this defect is found within the T cell subset, we backcrossed a transgene encoding bovine insulin (BI) onto the NZB background. In nonautoimmune BALB/c mice, the BI transgene induces a profound but incomplete state of T cell tolerance mediated predominantly by clonal anergy. Comparison of tolerance in NZB and BALB/c BI-transgenic mice clearly demonstrated that NZB T cells were at least as tolerant to BI as BALB/c T cells. NZB BI-transgenic mice did not spontaneously produce anti-BI Abs, and following antigenic challenge, BI-specific Ab production was comparably reduced in both BI-transgenic NZB and BALB/c mice. Further, in vitro BI-specific T cell proliferation and cytokine secretion were appropriately decreased for primed lymph node and splenic T cells derived from NZB BI-transgenic relative to their nontransgenic counterparts. These data indicate that a generalized T cell tolerance defect does not underlie the autoimmune disease in NZB mice. Instead, we propose that the T cell-dependent production of pathogenic IgG autoantibodies in these mice arises from abnormal activation of T cells in the setting of normal but incomplete tolerance.