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Objective Autoreactive IgE antibodies have been implicated in the pathogenesis of systemic lupus erythematosus (SLE). We hypothesize that omalizumab, a monoclonal antibody binding IgE, may improve SLE activity by reducing type I interferon (IFN) production by hampering plasmacytoid dendritic cells and basophil activation. This study was undertaken to assess the safety, tolerability, and clinical efficacy of omalizumab in mild to moderate SLE. Methods Sixteen subjects with SLE and a Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score of ≥4 and elevated autoreactive IgE antibody levels were randomized to receive omalizumab or placebo (2:1) for 16 weeks, followed by 16 weeks of open-label treatment and a 4-week washout period. The SLEDAI-2K score, British Isles Lupus Assessment Group index (BILAG 2004) score, and physician's global assessment of disease activity were recorded at each visit. The type I IFN-induced gene signature was determined using quantitative polymerase chain reaction. Results Omalizumab was well tolerated with no allergic reactions, and mostly mild adverse events comparable to those experienced with placebo treatment. SLEDAI-2K scores improved in the omalizumab group compared to the placebo group at week 16 (P = 0.038), as well as during the open-label phase in subjects initially receiving placebo (P = 0.02). No worsening in BILAG scores or the physician's global assessment was detected. There was a trend toward a reduction in IFN gene signature in subjects treated with omalizumab (P = 0.11), especially in subjects with a high baseline IFN signature (P = 0.052). Conclusion Our findings indicate that omalizumab is well tolerated in SLE and is associated with improvement in disease activity. Larger randomized clinical trials will be needed to assess the efficacy of omalizumab in patients with SLE.

Objective: To identify a genetic cause of early-onset systemic lupus erythematosus (SLE) in a large consanguineous family from Turkey and to study the mechanisms of disease. Methods: We performed whole exome sequencing (WES) and SNP array genotyping in affected and unaffected family members. Protein studies, gene expression, cytokine profiling, neutrophil extracellular trap formation, and presence of low-density granulocytes were evaluated in patient primary cells and serum samples. Results: We identified a novel homozygous loss-of-function mutation (p.Pro445Leufs*11) in the C1R gene. Sanger sequencing of 14 family members confirmed the homozygous mutation in four affected patients, and in an asymptomatic 9-year old female. Sera from patients with truncated C1r protein had low complement levels. Two affected siblings available for detailed evaluation exibited strong type I interferon inflammatory signatures despite being clinically inactive at the time of sampling. The type-I IFN transcriptional signature in patients' blood correlated with disease expressivity, whereas the neutrophil signature in patients' PBMCs was likely associated with disease severity. The affected female with the most severe phenotype, showed a stronger neutrophil signature, defined by enhanced neutrophil extracellular trap formation and the presence of low-density granulocytes. Analysis of exome data for modifying alleles suggested enrichment of common SLE-associated variants in the more severely affected patients. Lupus-associated HLA alleles or HLA haplotypes were not shared among the 4 affected subjects. Conclusion: We report a novel high-penetrance mutation in C1R as the cause of monogenic SLE. Disease expressivity in this family appears to be influenced by additional common and rare genetic variants. This article is protected by copyright. All rights reserved.

Objective Anticytokine autoantibodies occur across a range of hematologic, pulmonary, and infectious diseases. However, systematic investigation of their presence and significance in autoimmune diseases is lacking. This study was undertaken to examine the distinct functions of anticytokine autoantibodies in patients with systemic lupus erythematosus (SLE) compared to patients with other rheumatic diseases and healthy controls. Methods Serum samples from patients with SLE (n = 199), patients with primary Sjogren's syndrome (SS) (n = 150), patients with rheumatoid arthritis (RA) (n = 149), and healthy controls (n = 200) were screened for 24 anticytokine autoantibodies using a multiplex bead-based assay. To evaluate the biologic activity of anticytokine autoantibodies, their ability to block cytokine-induced signal transduction or protein expression was measured. RNA sequencing was performed on whole blood in a subset of healthy controls and patients with SLE. Results Patients with SLE and those with SS had a striking excess of autoantibodies against interferons and the interferon-responsive chemokine interferon-inducible protein 10 (IP-10). Only autoantibodies against type I interferon, interleukin-12 (IL-12), and IL-22 exhibited neutralizing activity. In SLE, the presence of anti–interferon-γ autoantibodies was correlated with more severe disease activity, higher levels of anti–double-stranded DNA antibodies, and elevated expression of interferon-α/β–inducible genes. Conversely, in SLE patients with blocking anti–interferon-α autoantibodies, the type I interferon gene expression signature was normalized. Anti–type III interferon autoantibodies (λ2, λ3) and anti–IP-10 autoantibodies were newly recognized in SLE patient serum, and autoantibodies against macrophage-colony stimulating factor, IL-4, IL-7, IL-17, and IL-22, none of which have been previously identified in rheumatic conditions, were discovered. Conclusion Anticytokine autoantibodies are associated with distinct patterns of disease in SLE, SS, and RA. Anti-interferon autoantibodies are overrepresented in patients with SLE and those with SS, and fall into distinct functional classes, with only a subset of anti–type I interferon antibodies exhibiting neutralizing activity. Anti–interferon-γ autoantibodies are correlated with increased disease activity and interferon-related gene expression, suggesting that such autoantibodies may contribute to the pathogenesis of SLE.

Objective Systemic lupus erythematosus (SLE) is characterized by increased cardiovascular risk in adult-onset and childhood-onset SLE (cSLE). Type I interferons (IFNs) appear to play a prominent role in premature vascular damage in adult SLE, at least in part, by inducing impairments in the phenotype and function of endothelial progenitor cells (EPCs), thereby hampering vascular repair. It is not clear if EPC dysfunction is present in cSLE in association with a type I IFN signature.

Objective Oxidative stress and oxidized high-density lipoprotein (HDL) are implicated as risk factors for cardiovascular disease (CVD) in systemic lupus erythematosus (SLE). Yet, how HDL is oxidized and rendered dysfunctional in SLE remains unclear. Neutrophil extracellular traps (NETs), the levels of which are elevated in lupus, possess oxidant-generating enzymes, including myeloperoxidase (MPO), NADPH oxidase (NOX), and nitric oxide synthase (NOS). We hypothesized that NETs mediate HDL oxidation, impairing cholesterol efflux capacity (CEC). Methods Plasma MPO levels and CEC activity were examined in controls and lupus patients, and 3-chlorotyrosine (MPO specific) and 3-nitrotyrosine (derived from reactive nitrogen species) were quantified in human HDL. Multivariable linear models were used to estimate and test differences between groups. HDL was exposed to NETs from control and lupus neutrophils in the presence or absence of MPO, NOX, NOS inhibitors, and chloroquine (CQ). Murine HDL oxidation was quantified after NET inhibition in vivo. Results SLE patients displayed higher MPO levels and diminished CEC compared to controls. SLE HDL had higher 3-nitrotyrosine and 3-chlorotyrosine content than control HDL, with site-specific oxidation signatures on apolipoprotein A-I. Experiments with human and murine NETs confirmed that chlorination was mediated by MPO and NOX, and nitration by NOS and NOX. Mice with lupus treated with the NET inhibitor Cl-amidine displayed significantly decreased HDL oxidation. CQ inhibited NET formation in vitro. Conclusion Active NOS, NOX, and MPO within NETs significantly modify HDL, rendering the lipoprotein proatherogenic. Since NET formation is enhanced in SLE, these findings support a novel role for NET-derived lipoprotein oxidation in SLE-associated CVD and identify additional proatherogenic roles of neutrophils and putative protective roles of antimalarials in autoimmunity.