Leptin is abnormally elevated in the plasma of patients with systemic lupus erythematosus (SLE), where it is thought to promote and/or sustain pro-inflammatory responses. Whether this association could reflect an increased genetic susceptibility to develop SLE is not known, and studies of genetic associations with leptin-related polymorphisms in SLE patients have been so far inconclusive. Here we genotyped DNA samples from 15,706 SLE patients and healthy matched controls from four different ancestral groups, to correlate polymorphisms of genes of the leptin pathway to risk for SLE. It was found that although several SNPs showed weak associations, those associations did not remain significant after correction for multiple testing. These data do not support associations between defined leptin-related polymorphisms and increased susceptibility to develop SLE.
systemic lupus erythematosus; leptin pathway; gene polymorphisms
Belimumab (Benlysta) is a human monoclonal antibody that inhibits soluble B-lymphocyte stimulator and was approved by the FDA for treatment of adults with systemic lupus erythematosus (SLE). This study evaluates the use and efficacy of belimumab in academic SLE practices.
Invitations to participate and complete a one-page questionnaire for each patient prescribed belimumab were sent to 16 physicians experienced in SLE Phase III clinical trials. The outcome was defined as the physician’s impression of improvement in the initial manifestation(s) being treated without worsening in other organ systems.
Of 195 patients treated with belimumab at 10 academic centers, 96% were on background medications for SLE at initiation of belimumab, with 74% on corticosteroids. The main indications for initiation of belimumab were arthritis, rash, and/or worsening serologic activity, with 30% of patients unable to taper corticosteroids. Of the 120 patients on belimumab for at least 6 months, 51% responded clinically and 67% had ≥25% improvement in laboratory values. While numbers are limited, black patients showed improvement at 6 months. In a subset of 39 patients with childhood-onset SLE, 65% responded favorably at 6 months, and 35% discontinued corticosteroids.
Our data demonstrate favorable clinical and laboratory outcomes in patients with SLE at 6 months across all racial and ethnic groups, with similar improvement seen among patients with childhood-onset SLE.
belimumab; lupus treatment; childhood-onset lupus
Since systemic lupus erythematosus (SLE) affects women of reproductive age, pregnancy is a major concern.
To identify predictors of adverse pregnancy outcome (APO) in inactive or stable active SLE patients
385 patients (49% non-Hispanic White; 31% prior nephritis) with SLE in PROMISSE. Exclusion criteria were: proteinuria >1000 mg/24 hour, creatinine >1.2 mg/dL, prednisone >20 mg/day, or multi-fetal pregnancy.
APO included: fetal/neonatal death; birth <36 weeks due to placental insufficiency, hypertension, or preeclampsia; and small for gestational age (SGA) <5%. Disease activity was assessed by SLEPDAI and physician's global assessment (PGA).
APO occurred in 19.0% (95% CI: 15.2% - 23.2%) of pregnancies, fetal death (4%), neonatal death (1%), preterm delivery (9%), and SGA (10%). Severe flares in the second and third trimester occurred in 2.5% and 3.0%, respectively. Baseline predictors of APO included lupus anticoagulant positive (OR = 8.32, 95% CI: 3.59-19.26), antihypertensive use (OR = 7.05, 95% CI: 3.05 - 16.31), PGA>1 (OR = 4.02, 95% CI: 1.84 - 8.82) and platelets (OR = 1.33 per 50K decrease, 95% CI:1.09-1.63); non-Hispanic White was protective (OR = 0.45, 95% CI: 0.24-0.84). Maternal flares, higher disease activity, and smaller increase in C3 later in pregnancy also predicted APO. Among women without baseline risk factors, the APO rate was 7.8%. For those either LAC positive, or LAC negative but non-White or Hispanic and taking antihypertensives, APO rate was 58%; fetal/neonatal mortality 22%.
Excluded patients with high disease activity.
In pregnant SLE patients with inactive or stable mild/moderate disease, severe flares are infrequent, and absent specific risk factors, outcomes are favorable.
Primary Funding Source
National Institutes of Health
Hydroxychloroquine is used for its effect on systemic lupus erythematosus (SLE) disease activity and long-term benefits. This can be limited by adherence. One way to assess adherence is to measure blood levels. Conflicting data exist regarding blood levels and disease activity. There is dosing controversy; rheumatologists recommend weight-based, while ophthalmologists advocate height-based ‘ideal body weight’ dosing.
Patients were prescribed hydroxychloroquine not to exceed 6.5mg/kg (max400mg/day). In hemodialysis, the dose was 200mg after each session, in renal insufficiency it was 200mg/day. Levels were measured at each visit with a therapeutic range of 500-2000 ng/ml. Patients were divided according to baseline blood level. To assess the impact of measurement and counseling on adherence, we compared the proportion of patients with a level of 500ng/ml or higher based on how many prior assessments the patient had.
The proportion of patients with hydroxychloroquine levels in the therapeutic range differed significantly by age, gender and vitamin D level. There was a trend toward lower levels with renal failure. Blood levels were similar regardless of height and ideal body weight. Comparing those with undetectable, sub-therapeutic and therapeutic levels, disease activity decreased (SLEDAI 2.92, 2.36 and 2.20)(P=0.04, for trend). At first, 56% were therapeutic and by the third measurement this increased to 80% (p =<0.0001).
There was a trend towards higher disease activity with lower hydroxychloroquine levels. Renal failure dosing led to sub-optimum levels. We show that weight-based dosing (max 400mg daily) is appropriate and that height does not appear to influence levels. Measurement, counseling and repeated testing can increase adherences rates.
Objective. Accelerated atherosclerosis is a major cause of morbidity and death in SLE. The purpose of this study was to determine whether the prevalence and extent of coronary artery calcium (CAC) is higher in female SLE patients compared with a non-SLE sample from the Multi-Ethnic Study of Atherosclerosis (MESA).
Methods. CAC was measured in 80 female SLE patients and 241 female MESA controls from the Baltimore Field Centre, ages 45–64 years, without evidence of clinical cardiovascular disease. Binary regression was used to estimate the ratio of CAC prevalence in SLE vs MESA controls, controlling for demographic and cardiovascular risk factors. To compare the groups with respect to the quantity of CAC among those with non-zero Agatston scores, we used linear models in which the outcome was a log-transformed Agatston score.
Results. The prevalence of CAC was substantially higher in SLE. The differences were most pronounced and statistically significant in those aged 45–54 years (58% vs 20%, P < 0.0001), but were still observed among those aged 55–65 years (57% vs 36%, P = 0.069). After controlling for age, ethnicity, education, income, diabetes mellitus, hypertension, hyperlipidaemia, high-density lipoprotein levels, smoking, education and BMI, SLE patients still had a significantly higher prevalence of CAC than controls. Among those with CAC, the mean log Agatston score did not differ significantly between SLE and MESA participants.
Conclusion. Women with SLE have a higher prevalence of CAC than comparable women without SLE, even after adjusting for traditional cardiovascular risk factors, especially among those aged 45–54 years.
systemic lupus erythematosus; atherosclerosis; coronary artery calcium; inflammation; MESA; computed tomography; statins; cardiovascular; Agatston score; cohort
Even though systemic lupus erythematosus (SLE) is associated with high morbidity and mortality rates among young and middle-aged women, the molecular mechanisms of disease pathogenesis are not fully understood. Previous studies from our laboratory suggested an association between oxidative stress and SLE disease activity (SLEDAI). To further assess the role of reactive oxygen species (ROS) in SLE, we examined the contribution of lipid-derived reactive aldehydes (LDRAs)-specific immune complexes in SLE. Sera from 60 SLE patients with varying SLEDAI and 32 age- and gender- matched healthy controls were analyzed for oxidative stress and related markers. Patients were divided into two groups based on their SLEDAI scores (<6 and ≥ 6). Both SLEDAI groups showed higher serum 4-hydroxynonenal (HNE)-/malondialdehyde (MDA)-protein adducts and their specific immune complexes (HNE-/MDA-specific ICs) together with IL-17 than the controls, but the levels were significantly greater in the high SLEDAI (≥ 6) group. Moreover, the serum levels of anti-oxidant enzymes Cu/Zn superoxide dismutase (SOD) and catalase (CAT) were significantly reduced in both patient groups compared to controls. Remarkably, for the first time, our data show that increased HNE-/MDA-specific ICs are positively associated with SLEDAI and elevated circulating immune complexes (CICs), suggesting a possible causal relationship among oxidative stress, LDRA-specific ICs and the development of SLE. Our findings, apart from providing firm support to an association between oxidative stress and SLE, also suggest that these oxidative stress markers, especially the HNE-/MDA-specific ICs, may be useful in evaluating the prognosis of SLE as well as in elucidating the mechanisms of disease pathogenesis.
Antibodies to nuclear antigens (antinuclear antibodies or ANAs) are the serological hallmark of systemic lupus erythematosus (SLE). These antibodies bind diverse nuclear antigens that include DNA, histones and non-histone proteins as well as complexes of proteins with DNA and RNA. Because of the frequency of ANA expression in SLE, testing is an important component of clinical evaluation as well as determination of eligibility for clinical trials or utilization of certain therapies. Immunofluorescence assays have been commonly used for this purpose although this approach can be limited by issues of throughput, variability and difficulty in determining positivity. ELISA and multiplex assays are also useful approaches although these assays may give an incomplete picture of antibodies present. To develop a sensitive and quantitative ANA assay, we have explored an ELISA platform in which plates are pre-coated with a positively charged nucleic acid binding polymer (NABP) to increase adherence of antigens containing DNA or RNA. As a source of antigens, we have used supernatants of Jurkat cells undergoing apoptosis in vitro. As results presented show, a poly-L-lysine (PLL) pre-coat significantly enhances detection of antibodies to DNA as well as antigens such as histones, SSA, SSB and RNP. Comparison of the ELISA assay with the PLL pre-coat with a multiplex assay using the BioPlex® 2200 system indicated good agreement in results for a panel of lupus sera. Together, these studies indicate that a pre-coat with a positively charged polymer can increase the sensitivity of an ANA ELISA using as antigens molecules released from dead and dying cells. This assay platform may facilitate ANA testing by providing an ensemble of antigens more similar in composition and structure with antigens present in vivo, with a NABP promoting adherence via charge-charge interactions.
Histone modifications set transcriptional competency and can perpetuate pathologic expression patterns. We defined systemic lupus erythematosus (SLE)-specific changes in H3K4me3 and K3K27me3, histone marks of gene activation and repression, respectively.
We used ChIP-seq to define histone modifications in monocytes from SLE patients and controls.
Both promoters and enhancers exhibited significant changes in histone methylation in SLE. Regions with differential H3K4me3 in SLE were significantly enriched in potential interferon-related transcription factor binding sites and pioneer transcription factor sites.
Enhancer activation defines the character of the cell and our data support extensive disease effects in monocytes, a particularly plastic lineage. Type I interferons not only drive altered gene expression but may also alter the character of the cell through chromatin modifications.
enhancer; epigenome; histone methylation; interferon; IRF1; lupus
To assess the efficacy/safety of the B-lymphocyte stimulator inhibitor belimumab/standard-of-care (SOC) versus placebo/SOC in active systemic lupus erythematosus (SLE).
In a multicenter, randomized, controlled, phase 3 trial, 819 antinuclear antibody- or anti-dsDNA-positive SLE patients with Safety of Estrogens in Lupus Erythematosus National Assessment–SLE Disease Activity Index (SELENA-SLEDAI) ≥ 6 were randomized (1:1:1 ratio) to receive intravenous belimumab 1 or 10 mg/kg, or placebo on days 0, 14, and 28, and then every 28 days for 72 weeks. Primary efficacy analyses: SLE Responder Index (SRI) at week 52 (≥ 4-point reduction in SELENA-SLEDAI; no new British Isles Lupus Assessment Group A and < 2 new B organ domain scores; no worsening in Physician’s Global Assessment).
Belimumab 10 mg/kg plus SOC met the primary efficacy endpoint: significantly greater SRI response at week 52 than placebo (43.2% versus 33.5%; P = 0.017); the rate with belimumab 1 mg/kg was 40.6% (P = 0.089). Week-76 response rates: 32.4%, 39.1%, and 38.5% with placebo, and belimumab 1 and 10 mg/kg, respectively. In post-hoc sensitivity analyses evaluating higher SELENA-SLEDAI thresholds, belimumab 10 mg/kg achieved better discrimination at weeks 52/76. Risk of severe SELENA-SLEDAI flares over 76 weeks was reduced with belimumab 1 mg/kg (34%; P = 0.023) and 10 mg/kg (23%; P = 0.13). Serious and severe adverse events including infections, laboratory abnormalities, malignancies, and deaths, were comparable across groups.
Belimumab plus SOC significantly improved SRI response rate, reduced SLE disease activity and severe flares, and was generally well-tolerated in SLE.
Monitoring disease activity in a complex, heterogeneous disease such as lupus is difficult. Both over- and undertreatment lead to damage. Current standard of care serologies are unreliable. Better measures of disease activity are necessary as we move into the era of precision medicine. We show here the use of a data-driven, modular approach to genomic biomarker development within lupus—specifically lupus nephritis.
The aim of this study was to determine the association of anti-Sm antibodies with clinical manifestations, comorbidities, and disease damage in a large multi-ethnic SLE cohort. SLE patients (per American College of Rheumatology criteria), age ≥16 years, disease duration ≤10 years at enrollment, and defined ethnicity (African American, Hispanic or Caucasian), from a longitudinal US cohort were studied. Socioeconomic-demographic features, cumulative clinical manifestations, comorbidities, and disease damage (as per the Systemic Lupus International Collaborating Clinics Damage Index [SDI]) were determined. The association of anti-Sm antibodies with clinical features was examined using multivariable logistic regression analyses adjusting for age, gender, ethnicity, disease duration, level of education, health insurance, and smoking. A total of 2322 SLE patients were studied. The mean (standard deviation, SD) age at diagnosis was 34.4 (12.8) years and the mean (SD) disease duration was 9.0(7.9)years; 2127 (91.6 %) were women. Anti-Sm antibodies were present in 579 (24.9 %) patients. In the multivariable analysis, anti-Sm antibodies were significantly associated with serositis, renal involvement, psychosis, vasculitis, Raynaud's phenomenon, hemolytic anemia, leukopenia, lymphopenia, and arterial hypertension. No significant association was found for damage accrual. In this cohort of SLE patients, anti-Sm antibodies were associated with several clinical features including serious manifestations such as renal, neurologic, and hematologic disorders as well as vasculitis.
Anti-Smith antibodies; Clinical manifestations; Disease damage; Systemic lupus erythematosus
To determine the frequency, clinical and autoantibody associations and outcome of mood disorders in a multi-ethnic/racial, prospective, inception cohort of SLE patients.
Patients were assessed annually for mood disorders (4 types as per DSM-IV) and 18 other neuropsychiatric (NP) events. Global disease activity (SLEDAI-2K), SLICC/ACR damage index (SDI) and SF-36 subscale, mental (MCS) and physical (PCS) component summary scores were collected. Time to event, linear and ordinal regressions and multi-state models were used as appropriate.
Of 1,827 SLE patients, 88.9% were female, 48.9% Caucasian, mean ± SD age 35.1±13.3 years, disease duration 5.6±4.8 months and follow-up 4.73±3.45 years. Over the study 863 (47.2%) patients had 1,627 NP events. Mood disorders occurred in 232/1827 (12.7%) patients and 98/256 (38.3%) events were attributed to SLE. The estimated cumulative incidence of any mood disorder after 10 years was 17.7% (95%CI=[15.1%,20.2%]). There was a greater risk of mood disorder in patients with concurrent NP events (p ≤ 0.01) and lower risk with Asian race/ethnicity (p=0.01) and immunosuppressive drugs (p=0.003). Mood disorders were associated with lower mental health subscale and MCS scores but not with SLEDAI-2K, SDI scores or lupus autoantibodies. Antidepressants were used in 168/232 (72.4%) patients with depression. 126/256 (49.2%) mood disorders resolved in 117/232 (50.4%) patients.
Mood disorders, the second most frequent NP event in SLE patients, have a negative impact on HRQoL and improve over time. The lack of association with global SLE disease activity, cumulative organ damage and lupus autoantibodies emphasize their multifactorial etiology and a role for non-lupus specific therapies.
Systemic lupus erythematosus; Mood disorders; Inception cohort; Outcomes research
Canonically, IgE mediates allergic immune responses by triggering mast cells and basophils to release histamine and Type 2 helper cytokines. Here, we report that in human systemic lupus erythematosus, IgE antibodies specific for double-stranded DNA activate plasmacytoid dendritic cells (pDCs), an immune cell type linked to viral defense, leading to the secretion of substantial amounts of interferon-α. The concentrations of dsDNA-specific IgE found in patient serum correlated with disease severity and greatly potentiated pDC functions by triggering phagocytosis via FcεRI followed by Toll-like receptor 9-mediated DNA sensing in phagosomes. These findings expand the known pathogenic mechanisms of IgE-mediated inflammation beyond those found in allergy and demonstrate that IgE can trigger interferon responses capable of exacerbating self-destructive autoimmune responses.
The Sydney classification criteria for antiphospholipid syndrome include lupus anticoagulant or moderate-to-high titre anticardiolipin IgG or IgM. We explored the association of all anticardiolipin isotypes, lupus anticoagulant and the combination with venous and arterial thrombosis.
Patients with systemic lupus erythematosus (SLE) in a large clinical cohort seen quarterly were repeatedly tested by protocol for anticardiolipin antibodies and lupus anticoagulant. Subgroups of patients were defined based on the geometric mean titres of IgG, IgM, IgA anticardiolipin and lupus anticoagulant expressed in dilute Russell's viper venom time (RVVT) seconds for each patient across all cohort visits. These subgroups were compared with respect rates of thrombosis since diagnosis with SLE. Rate ratios were estimated using Cox Proportional Hazards models.
Of the 1390 cohort members included, there were 284 thrombotic events observed over 17 025 person-years since diagnosis for a rate of 1.7 events per 100 person-years. Those with a geometric mean titre of IgG anticardiolipin >20 had a significantly elevated rate of thromboses (rate ratio 1.8, p=0.0052), whereas there was no evidence of an association between thromboses and elevated IgM geometric mean (rate ratio 1.2, p=0.40). There were relatively few cohort members with elevated IgA geometric mean but the rate of thromboses in that group was elevated (rate ratio 1.7, p=0.23). The associations between anticardiolipin antibodies and thromboses were strongest when considering venous thromboses. Those with two or more elevated anticardiolipin isotypes or those with both IgG anticardiolipin and RVVT did not appear at higher risk than those with a single elevated marker.
This study supports previous observations that IgG anticardiolipin and lupus anticoagulant are associated with higher rates of thromboses. Our power to study IgA anticardiolipin was limited due to small number of patients with elevated IgA.
Anticardiolipin Antibodies; Antiphospholipid Antibodies; Antiphospholipid Syndrome; Systemic Lupus Erythematosus
High titer, class-switched autoantibodies are a hallmark of systemic lupus erythematosus (SLE). Dysregulation of the interferon (IFN) pathway is observed in individuals with active SLE, although the association of specific autoantibodies with chemokine score, a combined measurement of three IFN-regulated chemokines, is not known. To identify autoantibodies associated with chemokine score, we developed giant magnetoresistive (GMR) biosensor microarrays, which allow the parallel measurement of multiple serum antibodies to autoantigens and peptides. We used the microarrays to analyze serum samples from SLE patients and found individuals with high chemokine scores had significantly greater reactivity to 13 autoantigens than individuals with low chemokine scores. Our findings demonstrate that multiple autoantibodies, including antibodies to U1-70K and modified histone H2B tails, are associated with IFN dysregulation in SLE. Further, they show the microarrays are capable of identifying autoantibodies associated with relevant clinical manifestations of SLE, with potential for use as biomarkers in clinical practice.
Complement is a major effector arm of the innate immune system that responds rapidly to pathogens or altered self. The central protein of the system, C3, participates in an amplification loop that can lead to rapid complement deposition on a target and, if excessive, can result in host tissue damage. Currently, complement activation is routinely monitored by assessing total C3 levels, which is an indirect and relatively insensitive method. An alternative approach would be to measure downstream C3 activation products such as C3a or iC3b. However, in vitro activation can produce falsely elevated levels of these biomarkers. To circumvent this issue, a lateral flow immunoassay system was developed that measures iC3b in whole blood, plasma and serum and avoids in vitro activation by minimizing sample handling. This assay system returns results in 15 minutes and specifically measures iC3b while having minimal cross-reactivity to other C3 split products. While evaluating the potential of this assay, it was observed that circulating iC3b levels can distinguish healthy individuals from those with complement activation-associated diseases. This tool is engineered to provide an improved method to assess complement activation at point-of-care and could facilitate studies to monitor disease progression in a variety of inflammatory conditions.
Complement activation; iC3b biomarker; lateral flow assay; lupus; intracerebral hemorrhage (ICH)
An association between 25-hydroxyvitamin D (25[OH]D; vitamin D) deficiency and increased cardiovascular (CV) risk factors and CV disease (CVD) has been shown in general population studies. Vitamin D deficiency has been noted in systemic lupus erythematosus (SLE), and CVD is a major cause of morbidity and mortality in SLE. The objectives of this study were to estimate the associations of 25(OH)D levels with CV risk factors and to determine whether low baseline 25(OH)D levels predict future CV events in patients participating in an international inception cohort.
Data were collected on 890 participants, including demographics, SLE activity and damage assessments, CV risk factors and events, medications, laboratory assessments of 25(OH)D levels, and inflammatory markers. Multiple logistic and Cox regressions were used to estimate the associations of baseline 25(OH)D levels with baseline CV risk factors and CVD events. The models were adjusted for age, sex, race, season, and country, with and without body mass index.
Patients in the higher quartiles of 25(OH)D were less likely to have hypertension and hyperlipidemia and were more likely to have lower C-reactive protein levels and lower Systemic Lupus Erythematosus Disease Activity Index 2000 scores at baseline when compared with the first quartile. Vitamin D levels were not independently associated with CVD event incidence; however, hazard ratios for CVD event incidence decreased with successively higher quartiles.
Lower baseline 25(OH)D levels are associated with higher risk for CV risk factors and more active SLE at baseline. There may be a trend toward a lower likelihood of CVD events in those with higher baseline 25(OH)D levels.
IRF1 both mediates responses to type I interferons and the induction of interferons. It has been implicated in murine lupus models as a critical mediator of inflammation. A previous study of chromatin modifications in SLE patient monocytes implicated IRF1 as associated with increased histone acetylation in SLE patients. This study directly investigated IRF1 binding sites on chromatin using ChIP-seq.
Nine female SLE patients and seven female controls were examined. Monocytes were purified from peripheral blood and subjected to library preparation using a validated antibody to IRF1. The effect of IRF1 on target gene expression was confirmed using an overexpression system in cell lines and co-immunoprecipitation was used to define protein interactions.
IRF1 binding around transcribed regions was increased in SLE patient monocytes but histone modifications at potential IRF1 binding sites without detectable IRF1 binding were also increased. IRF1 overexpression was sufficient to drive transcription of target genes. IRF1 overexpression was also able to alter histone modifications at a focus set of target genes and the use of an IRF1 inhibitor decreased both expression and histone modifications at target genes. IRF1 was found to interact with a select set of histone modifying enzymes and other transcription factors.
IRF1 is an important signaling protein in the interferon pathway. IRF1 not only activates gene expression as a transcription factor but may perpetuate disease by leading to a dysregulated epigenome.
The autoimmune disease systemic lupus erythematosus (SLE) has a modified epigenome with modified tri-methylation of histone H3 lysine 4 (H3K4me3) at specific loci across the genome. H3K4me3 is a canonical chromatin mark of active transcription. Recent studies have suggested that H3K4me3 breadth has an important regulatory role in cell identity. This project examined H3K4me3 breadth at transcription start sites (TSS) in primary monocytes and its association with differential gene transcription in SLE.
Integrative analysis was applied to chromatin immunoprecipitation sequencing (ChIP-seq) and RNA sequencing (RNA-seq) data generated from primary monocytes as well as genomic data available in public repositories. Four distinctive H3K4me3 patterns of ChIP-seq peaks were identified at 8399 TSSs. Narrow peaks were highly enriched with genes related to housekeeping functions. The broader peaks with extended H3K4me3 immediately upstream and/or downstream of TSS were associated with immune response genes. Many TSSs had downstream H3K4me3 extended to ~650 bp, where the transition of H3K4me3 to H3K36me3, a transcriptional elongation mark, is often found. The H3K4me3 pattern was strongly associated with transcription in SLE. Genes with narrow peaks were less likely (OR = 0.14, p = 2 × 10−4) while genes with extended downstream H3K4me3 were more likely (OR = 2.37, p = 1 × 10−11) to be overexpressed in SLE. Of the genes significantly overexpressed in SLE, 78.8 % had increased downstream H3K4me3 while only 47.1 % had increased upstream H3K4me3. Gene transcription sensitively and consistently responded to H3K4me3 change downstream of TSSs. Every 1 % increase of H3K4me3 in this region leads to ~1.5 % average increase of transcription.
We identified the immediate TSS downstream nucleosome as a crucial regulator responsible for transcription changes in SLE. This study applied a unique method to study the effect of H3K4me3 breadth on diseases and revealed new insights about epigenetic modifications in SLE, which could lead to novel treatments.
Electronic supplementary material
The online version of this article (doi:10.1186/s13148-016-0179-4) contains supplementary material, which is available to authorized users.
Systemic lupus erythematosus; H3K4me3; Epigenome; Integrative analysis; Pattern recognition
Histone acetylation modulates gene expression and has been described as increased in systemic lupus erythematosus (SLE). We investigated interferon regulatory factor 1 (IRF1) interactions that influence H4 acetylation (H4ac) in SLE. Intracellular flow cytometry for H4 acetylated lysine (K) 5, K8, K12, and K16 was performed. Histone acetylation was defined in monocytes and T cells from controls and SLE patients. RNA-Seq studies were performed on monocytes to look for an imbalance in histone acetyltransferases and histone deacetylase enzyme expression. Expression levels were validated using real-time quantitative RT-PCR. IRF1 induction of H4ac was evaluated using D54MG cells overexpressing IRF1. IRF1 protein interactions were studied using co-immunoprecipitation assays. IRF1-dependent recruitment of histone acetyltransferases to target genes was examined by ChIP assays using p300 antibody. Flow cytometry data showed significantly increased H4K5, H4K8, H4K12, and H4K16 acetylation in SLE monocytes. HDAC3 and HDAC11 gene expression were decreased in SLE monocytes. PCAF showed significantly higher gene expression in SLE than controls. IRF1-overexpressing D54MG cells were associated with significantly increased H4K5, H4K8, and H4K12 acetylation compared to vector-control D54MG cells both globally and at specific target genes. Co-immunoprecipitation studies using D54MG cells revealed IRF1 protein-protein interactions with PCAF, P300, CBP, GCN5, ATF2, and HDAC3. ChIP experiments demonstrated increased p300 recruitment to known IRF1 targets in D54MG cells overexpressing IRF1. In contrast, p300 binding to IRF1 targets decreased in D54MG cells with IRF1 knockdown. SLE appears to be associated with an imbalance in histone acetyltransferases and histone deacetylase enzymes favoring pathologic H4 acetylation. Furthermore, IRF1 directly interacts with chromatin modifying enzymes, supporting a model where recruitment to specific target genes is mediated in part by IRF1.
epigenetics; histone acetylation; histone modifications; interferons; IRF; IRF1; lupus; SLE
Systemic lupus erythematosus (SLE; OMIM 152700) is characterised by the production of antibodies to nuclear antigens. We previously identified variants in complement receptor 2 (CR2/CD21) that were associated with decreased risk of SLE. This study aimed to identify the causal variant for this association.
Genotyped and imputed genetic variants spanning CR2 were assessed for association with SLE in 15 750 case-control subjects from four ancestral groups. Allele-specific functional effects of associated variants were determined using quantitative real-time PCR, quantitative flow cytometry, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP)-PCR.
The strongest association signal was detected at rs1876453 in intron 1 of CR2 (pmeta=4.2×10−4, OR 0.85), specifically when subjects were stratified based on the presence of dsDNA autoantibodies (case-control pmeta=7.6×10−7, OR 0.71; case-only pmeta=1.9×10−4, OR 0.75). Although allele-specific effects on B cell CR2 mRNA or protein levels were not identified, levels of complement receptor 1 (CR1/CD35) mRNA and protein were significantly higher on B cells of subjects harbouring the minor allele (p=0.0248 and p=0.0006, respectively). The minor allele altered the formation of several DNA protein complexes by EMSA, including one containing CCCTC-binding factor (CTCF), an effect that was confirmed by ChIP-PCR.
These data suggest that rs1876453 in CR2 has long-range effects on gene regulation that decrease susceptibility to lupus. Since the minor allele at rs1876453 is preferentially associated with reduced risk of the highly specific dsDNA autoantibodies that are present in preclinical, active and severe lupus, understanding its mechanisms will have important therapeutic implications.
Systemic Lupus Erythematosus; Autoantibodies; Gene Polymorphism; B cells
Exploiting genotyping, DNA sequencing, imputation and trans-ancestral mapping, we used Bayesian and frequentist approaches to model the IRF5–TNPO3 locus association, now implicated in two immunotherapies and seven autoimmune diseases. Specifically, in systemic lupus erythematosus (SLE), we resolved separate associations in the IRF5 promoter (all ancestries) and with an extended European haplotype. We captured 3230 IRF5–TNPO3 high-quality, common variants across 5 ethnicities in 8395 SLE cases and 7367 controls. The genetic effect from the IRF5 promoter can be explained by any one of four variants in 5.7 kb (P-valuemeta = 6 × 10−49; OR = 1.38–1.97). The second genetic effect spanned an 85.5-kb, 24-variant haplotype that included the genes IRF5 and TNPO3 (P-valuesEU = 10−27–10−32, OR = 1.7–1.81). Many variants at the IRF5 locus with previously assigned biological function are not members of either final credible set of potential causal variants identified herein. In addition to the known biologically functional variants, we demonstrated that the risk allele of rs4728142, a variant in the promoter among the lowest frequentist probability and highest Bayesian posterior probability, was correlated with IRF5 expression and differentially binds the transcription factor ZBTB3. Our analytical strategy provides a novel framework for future studies aimed at dissecting etiological genetic effects. Finally, both SLE elements of the statistical model appear to operate in Sjögren's syndrome and systemic sclerosis whereas only the IRF5–TNPO3 gene-spanning haplotype is associated with primary biliary cirrhosis, demonstrating the nuance of similarity and difference in autoimmune disease risk mechanisms at IRF5–TNPO3.
We previously reported that lupus anticoagulant (LAC) is the main predictor of poor pregnancy outcome in antiphospholipid antibody (aPL)-positive patients. We sought to confirm this finding in an independent group of patients who were subsequently recruited into the PROMISSE study.
The PROMISSE study is a multicentre, prospective, observational study of pregnancy outcomes in women with aPL and/or systemic lupus erythematosus (SLE) that enrolled patients from 2003 to 2015. All consecutive, aPL-positive patients from the PROMISSE study who completed their pregnancy between April 2011 and January 2015 (after the previous PROMISSE report) are included in the current report. Patients were followed monthly until delivery, and aPL was tested at first, second and third trimesters of pregnancy and at 12 weeks post partum. Adverse pregnancy outcomes (APOs) were defined as fetal death after 12 weeks of gestation, neonatal death, delivery prior to 36 weeks of gestation due to pre-eclampsia or placental insufficiency or small-for-gestational age (birth weight <5th percentile).
Forty-four aPL-positive patients are included in this paper. Thirteen patients had APOs, which occurred in 80% of cases during the second trimester of pregnancy. LAC was present in 69% of patients with APOs compared with 27% of patients without APOs (p=0.01). No association was found between anticardiolipin antibodies (aCL) or anti-β2 glycoprotein I antibodies (aβ2GPI) IgG or IgM positivity and APOs. Definite antiphospholipid syndrome (history of thrombosis and/or pregnancy morbidity and aPL) was found in 92% of patients with any APOs compared with 45% of patients without APOs (p=0.004). Conversely, the frequency of SLE was not statistically different between those with and without APOs (30% vs 39%).
Our findings, in an independent group of aPL-positive patients from the PROMISSE study, confirm that LAC, but not aCL and aβ2GPI, is predictive of poor pregnancy outcomes after 12 weeks of pregnancy.
Trial registration number
Antiphospholipid Antibodies; Lupus Anticoagulant; Pregnancy; Antiphospholipid Syndrome; Systemic Lupus Erythematosus
Anti-C1q has been associated with systemic lupus erythematosus (SLE) and lupus nephritis in previous studies. We studied anti-C1q specificity for SLE (vs. rheumatic disease controls) and the association with SLE manifestations in an international multi-center study.
Information and blood samples were obtained in a cross-sectional study from patients with SLE (n=308) and other rheumatologic diseases (n=389) from 25 clinical sites (84% female, 68% Caucasian, 17% African descent, 8% Asian, 7% other). IgG anti-C1q against the collagen-like region was measured by ELISA.
Prevalence of anti-C1q was 28% (86/308) in patients with SLE and 13% (49/389) in controls (OR=2.7, 95% CI: 1.8-4, p<0.001). Anti-C1q was associated with proteinuria (OR=3.0, 95% CI: 1.7-5.1, p<0.001), red cell casts (OR=2.6, 95% CI: 1.2-5.4, p=0.015), anti-dsDNA (OR=3.4, 95% CI: 1.9-6.1, p<0.001) and anti-Smith (OR=2.8, 95% CI: 1.5-5.0, p=0.01). Anti-C1q was independently associated with renal involvement after adjustment for demographics, ANA, anti-dsDNA and low complement (OR=2.3, 95% CI: 1.3-4.2, p<0.01). Simultaneously positive anti-C1q, anti-dsDNA and low complement was strongly associated with renal involvement (OR=14.9, 95% CI: 5.8-38.4, p<0.01).
Anti-C1q was more common in patients with SLE and those of Asian race/ethnicity. We confirmed a significant association of anti-C1q with renal involvement, independent of demographics and other serologies. Anti-C1q in combination with anti-dsDNA and low complement was the strongest serological association with renal involvement. These data support the usefulness of anti-C1q in SLE, especially in lupus nephritis.
Multiple factors, including proteinuria, antiphospholipid syndrome, thrombocytopenia and hypertension, are predictive of pregnancy loss in systemic lupus erythematosus (SLE). In the PROMISSE study of predictors of pregnancy loss, only a battery of lupus anticoagulant tests was predictive of a composite of adverse pregnancy outcomes. We examined the predictive value of one baseline lupus anticoagulant test (dilute Russell viper venom time) with pregnancy loss in women with SLE.
From the Hopkins Lupus Cohort, there were 202 pregnancies from 175 different women after excluding twin pregnancies and pregnancies for which we did not have a first trimester assessment of lupus anticoagulant. We determined the percentage of women who had a pregnancy loss in groups defined by potential risk factors. The lupus anticoagulant was determined by dilute Russell viper venom time with appropriate mixing and confirmatory testing. Generalised estimating equations were used to calculate p values, accounting for repeated pregnancies in the same woman.
The age at pregnancy was <20 years (2%), 20–29 (53%), 30–39 (41%) and >40 (3%). 55% were Caucasian and 34% African-American. Among those with lupus anticoagulant during the first trimester, 6/16 (38%) experienced a pregnancy loss compared with only 16/186 (9%) of other pregnancies (p=0.003). In addition, those with low complement or higher disease activity had a higher rate of pregnancy loss than those without (p=0.049 and 0.005, respectively). In contrast, there was no association between elevated anticardiolipin in the first trimester and pregnancy loss.
The strongest predictor of pregnancy loss in SLE in the first trimester is the lupus anticoagulant. In addition, moderate disease activity by the physician global assessment and low complement measured in the first trimester were predictive of pregnancy loss. These data suggest that treatment of the lupus anticoagulant could be considered, even in the absence of history of pregnancy loss.
Antiphospholipid Antibodies; Systemic Lupus Erythematosus; Outcomes research