High serum IFN-alpha activity is a heritable risk factor for systemic lupus erythematosus

The Role of Clinical Features and Serum Biomarkers in Identifying Patients with Incomplete Lupus Erythematosus at Higher Risk of Transitioning to Systemic Lupus Erythematosus: Current Perspectives

Discovery of antinuclear antibodies (ANA) enabled earlier diagnosis of systemic lupus erythematosus (SLE) and other ANA⁺ connective tissue diseases (CTD). Rheumatologists increasingly encounter high referral volume of ANA⁺ patients. It has been estimated that only a small percentage of these patients will eventually transition to either SLE or other specified CTD. Incomplete lupus erythematosus (ILE) has been defined as a subset of patients who have some SLE-specific clinical manifestations but do not meet currently accepted classification criteria for SLE. Several studies have been performed with the goal of identifying clinical features, serum and tissue biomarkers that can distinguish those patients with ILE at risk of transitioning to SLE from those who will not. Increased autoantibody diversity, presence of anti-double-stranded DNA (dsDNA) antibodies, high expression of type I and type II interferon (IFN)-gene products, increased serum levels of B-cell-activating factor of the TNF family (BAFF), and certain serum cytokines and complement products have been identified as markers with positive predictive value, particularly when combined together. Once this patient population is better characterized biochemically, clinical trials should be considered with the primary objective to completely halt or slow down the transition from ILE to SLE. Hydroxychloroquine (HCQ) appears to be a promising agent due to its good tolerability and low toxicity profile and open-label studies in ILE patients have already shown its ability to delay the onset of SLE. Other therapeutics, like those targeting abnormal type I and type II IFN-signatures, B-cell specific signaling pathways, complement activation pathways and high BAFF levels should also be evaluated, but the risk to benefit ratio must be carefully determined before they can be considered.

Evaluation of Immune Response and Disease Status in Systemic Lupus Erythematosus Patients Following SARS-CoV-2 Vaccination

OBJECTIVE

To evaluate seroreactivity and disease flares after COVID-19 vaccination in a multiethnic/multiracial cohort of patients with systemic lupus erythematosus (SLE).

METHODS

Ninety SLE patients and 20 healthy controls receiving a complete COVID-19 vaccine regimen were included. IgG seroreactivity to the SARS-CoV-2 spike receptor-binding domain (RBD) and SARS-CoV-2 microneutralization were used to evaluate B cell responses; interferon-γ (IFNγ) production was measured by enzyme-linked immunospot (ELISpot) assay in order to assess T cell responses. Disease activity was measured by the hybrid SLE Disease Activity Index (SLEDAI), and flares were identified according to the Safety of Estrogens in Lupus Erythematosus National Assessment-SLEDAI flare index.

RESULTS

Overall, fully vaccinated SLE patients produced significantly lower IgG antibodies against SARS-CoV-2 spike RBD compared to fully vaccinated controls. Twenty-six SLE patients (28.8%) generated an IgG response below that of the lowest control (<100 units/ml). In logistic regression analyses, the use of any immunosuppressant or prednisone and a normal anti-double-stranded DNA antibody level prior to vaccination were associated with decreased vaccine responses. IgG seroreactivity to the SARS-CoV-2 spike RBD strongly correlated with the SARS-CoV-2 microneutralization titers and correlated with antigen-specific IFNγ production determined by ELISpot. In a subset of patients with poor antibody responses, IFNγ production was similarly diminished. Pre- and postvaccination SLEDAI scores were similar in both groups. Postvaccination flares occurred in 11.4% of patients; 1.3% of these were severe.

CONCLUSION

In a multiethnic/multiracial study of SLE patients, 29% had a low response to the COVID-19 vaccine which was associated with receiving immunosuppressive therapy. Reassuringly, severe disease flares were rare. While minimal protective levels remain unknown, these data suggest that protocol development is needed to assess the efficacy of booster vaccination.

High Systemic Type I Interferon Activity is Associated with Active Class III/IV Lupus Nephritis

OBJECTIVE

Previous studies suggest a link between high serum type I interferon (IFN) and lupus nephritis (LN). We determined whether serum IFN activity is associated with subtypes of LN and studied renal tissues and cells to understand the impact of IFN in LN.

METHODS

221 systemic lupus erythematosus (SLE) patients were studied. Serum IFN activity was measured by WISH bioassay. mRNA in-situ hybridization was used in renal tissue to measure expression of the representative IFN-induced gene, interferon-induced protein with tetratricopeptide repeats-1 (IFIT1), and the plasmacytoid dendritic cell (pDC) marker gene C-type lectin domain family-4 member C (CLEC4C or BDCA2). Podocyte cell line gene expression was measured by real-time PCR.

RESULTS

Class III/IV LN prevalence was significantly increased in patients with high serum IFN compared with those with low IFN (OR=5.48, p=4.0x10-7). In multivariate regression models, type I IFN was a stronger predictor of class III/IV LN than complement C3 or anti-dsDNA antibody, and could account for the association of these variables with LN. IFIT1 expression was increased in all classes of LN, but most in the glomerular areas of active class III/IV LN kidneys. IFIT1 expression was not closely co-localized with pDCs. IFN directly activated podocyte cell lines to induce chemokines and proapoptotic molecules.

CONCLUSION

Systemic high IFN is involved in the pathogenesis of severe LN. We do not find co-localization of pDCs with IFN signature in renal tissue, and instead observe the greatest intensity of IFN signature in glomerular areas, which could suggest a blood source of IFN.

Immunosuppression in Rheumatologic and Auto-immune Disease

Many rheumatologic diseases are thought to originate in dysregulation of the immune system; lupus nephritis, for example, involves humoral immunity, while autoinflammatory diseases such as familial Mediterranean fever are caused by defects in innate immunity. Of note, this dysregulation may involve both upregulation of immune system components and aspects of immunodeficiency. Treatment of rheumatologic diseases thus requires a familiarity with a variety of immunosuppressive medications and their effects on immune system function.In many rheumatologic conditions, due to an incompletely elucidated mechanism of disease, immunosuppression is relatively broad in contrast to agents used, for example, in treatment of transplant rejection. Multiple immunosuppressive drugs may also be used in succession or in combination. As such, an understanding of the mechanisms and targets of immunosuppressive drugs is essential to appreciating their utility and potential adverse effects. Because of the overlap between therapies used in rheumatologic as well as other inflammatory disorders, some of these medications are discussed in other disease processes (e.g., Immunosuppression for inflammatory bowel disease) or in greater detail in other chapters of this textbook (corticosteroids, mTOR inhibitors, antiproliferative agents).

Cytokines as Biomarkers in Systemic Lupus Erythematosus: Value for Diagnosis and Drug Therapy

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disease. The disease is characterized by activation and dysregulation of both the innate and the adaptive immune systems. The autoimmune response targets self-molecules including cell nuclei, double stranded DNA and other intra and extracellular structures. Multiple susceptibility genes within the immune system have been identified, as well as disturbances in different immune pathways. SLE may affect different organs and organ systems, and organ involvement is diverse among individuals. A universal understanding of pathophysiological mechanism of the disease, as well as directed therapies, are still missing. Cytokines are immunomodulating molecules produced by cells of the immune system. Interferons (IFNs) are a broad group of cytokines, primarily produced by the innate immune system. The IFN system has been observed to be dysregulated in SLE, and therefore IFNs have been extensively studied with a hope to understand the disease mechanisms and identify novel targeted therapies. In several autoimmune diseases identification and subsequent blockade of specific cytokines has led to successful therapies, for example tumor necrosis factor-alpha (TNF-α) inhibition in rheumatoid arthritis. Authors of this review have sought corresponding developments in SLE. In the current review, we cover the actual knowledge on IFNs and other studied cytokines as biomarkers and treatment targets in SLE.

Abnormalities of the type I interferon signaling pathway in lupus autoimmunity

Type I interferons (IFNs), mostly IFNα and IFNβ, and the type I IFN Signature are important in the pathogenesis of Systemic Lupus Erythematosus (SLE), an autoimmune chronic condition linked to inflammation. Both IFNα and IFNβ trigger a signaling cascade that, through the activation of JAK1, TYK2, STAT1 and STAT2, initiates gene transcription of IFN stimulated genes (ISGs). Noteworthy, other STAT family members and IFN Responsive Factors (IRFs) can also contribute to the activation of the IFN response. Aberrant type I IFN signaling, therefore, can exacerbate SLE by deregulated homeostasis leading to unnecessary persistence of the biological effects of type I IFNs. The etiopathogenesis of SLE is partially known and considered multifactorial. Family-based and genome wide association studies (GWAS) have identified genetic and transcriptional abnormalities in key molecules directly involved in the type I IFN signaling pathway, namely TYK2, STAT1 and STAT4, and IRF5. Gain-of-function mutations that heighten IFNα/β production, which in turn maintains type I IFN signaling, are found in other pathologies like the interferonopathies. However, the distinctive characteristics have yet to be determined. Signaling molecules activated in response to type I IFNs are upregulated in immune cell subsets and affected tissues of SLE patients. Moreover, Type I IFNs induce chromatin remodeling leading to a state permissive to transcription, and SLE patients have increased global and gene-specific epigenetic modifications, such as hypomethylation of DNA and histone acetylation. Epigenome wide association studies (EWAS) highlight important differences between SLE patients and healthy controls in Interferon Stimulated Genes (ISGs). The combination of environmental and genetic factors may stimulate type I IFN signaling transiently and produce long-lasting detrimental effects through epigenetic alterations. Substantial evidence for the pathogenic role of type I IFNs in SLE advocates the clinical use of neutralizing anti-type I IFN receptor antibodies as a therapeutic strategy, with clinical studies already showing promising results. Current and future clinical trials will determine whether drugs targeting molecules of the type I IFN signaling pathway, like non-selective JAK inhibitors or specific TYK2 inhibitors, may benefit people living with lupus.

Type I interferon detection in autoimmune diseases: challenges and clinical applications

INTRODUCTION

Accumulating data highlights that the dysregulation of type I interferon (IFN) pathways plays a central role in the pathogenesis of several systemic and organ-specific autoimmune diseases. Advances in understanding the role of type I IFNs in these disorders can lead to targeted drug development as well as establishing potential disease biomarkers.

AREAS COVERED

Here, we summarize current knowledge regarding the role of type I IFNs in the major systemic, as well as organ-specific, autoimmune disorders, including prominent inflammatory CNS disorders like multiple sclerosis.

EXPERT OPINION

Type I IFN involvement and its clinical associations in a wide spectrum of autoimmune diseases represents a promising area for research aiming to unveil common pathogenetic pathways in systemic and organ-specific autoimmunity.

Interferons in Systemic Lupus Erythematosus

Skewing of type I interferon (IFN) production and responses is a hallmark of systemic lupus erythematosus (SLE). Genetic and environmental contributions to IFN production lead to aberrant innate and adaptive immune activation even before clinical development of disease. Basic and translational research in this arena continues to identify contributions of IFNs to disease pathogenesis, and several promising therapeutic options for targeting of type I IFNs and their signaling pathways are in development for treatment of SLE patients.

Monogenic Autoinflammatory Diseases: State of the Art and Future Perspectives

Systemic autoinflammatory diseases are a heterogeneous family of disorders characterized by a dysregulation of the innate immune system, in which sterile inflammation primarily develops through antigen-independent hyperactivation of immune pathways. In most cases, they have a strong genetic background, with mutations in single genes involved in inflammation. Therefore, they can derive from different pathogenic mechanisms at any level, such as dysregulated inflammasome-mediated production of cytokines, intracellular stress, defective regulatory pathways, altered protein folding, enhanced NF-kappaB signalling, ubiquitination disorders, interferon pathway upregulation and complement activation. Since the discover of pathogenic mutations of the pyrin-encoding gene MEFV in Familial Mediterranean Fever, more than 50 monogenic autoinflammatory diseases have been discovered thanks to the advances in genetic sequencing: the advent of new genetic analysis techniques and the discovery of genes involved in autoinflammatory diseases have allowed a better understanding of the underlying innate immunologic pathways and pathogenetic mechanisms, thus opening new perspectives in targeted therapies. Moreover, this field of research has become of great interest, since more than a hundred clinical trials for autoinflammatory diseases are currently active or recently concluded, allowing us to hope for considerable acquisitions for the next few years. General paediatricians need to be aware of the importance of this group of diseases and they should consider autoinflammatory diseases in patients with clinical hallmarks, in order to guide further examinations and refer the patient to a specialist rheumatologist. Here we resume the pathogenesis, clinical aspects and diagnosis of the most important autoinflammatory diseases in children.

Type I Interferons in Systemic Autoimmune Diseases: Distinguishing Between Afferent and Efferent Functions for Precision Medicine and Individualized Treatment

A sustained increase in type I interferon (IFN-I) may accompany clinical manifestations and disease activity in systemic autoimmune diseases (SADs). Despite the very frequent presence of IFN-I in SADs, clinical manifestations are extremely varied between and within SADs. The present short review will address the following key questions associated with high IFN-I in SADs in the perspective of precision medicine. 1) What are the mechanisms leading to high IFN-I? 2) What are the predisposing conditions favoring high IFN-I production? 3) What is the role of IFN-I in the development of distinct clinical manifestations within SADs? 4) Would therapeutic strategies targeting IFN-I be helpful in controlling or even preventing SADs? In answering these questions, we will underlie areas of incertitude and the intertwined role of autoantibodies, immune complexes, and neutrophils.

Sustained high expression of multiple APOBEC3 cytidine deaminases in systemic lupus erythematosus

APOBEC3 (A3) enzymes are best known for their role as antiviral restriction factors and as mutagens in cancer. Although four of them, A3A, A3B, A3F and A3G, are induced by type-1-interferon (IFN-I), their role in inflammatory conditions is unknown. We thus investigated the expression of A3, and particularly A3A and A3B because of their ability to edit cellular DNA, in Systemic Lupus Erythematosus (SLE), a chronic inflammatory disease characterized by high IFN-α serum levels. In a cohort of 57 SLE patients, A3A and A3B, but also A3C and A3G, were upregulated ~ 10 to 15-fold (> 1000-fold for A3B) compared to healthy controls, particularly in patients with flares and elevated serum IFN-α levels. Hydroxychloroquine, corticosteroids and immunosuppressive treatment did not reverse A3 levels. The A3AΔ3B polymorphism, which potentiates A3A, was detected in 14.9% of patients and in 10% of controls, and was associated with higher A3A mRNA expression. A3A and A3B mRNA levels, but not A3C or A3G, were correlated positively with dsDNA breaks and negatively with lymphopenia. Exposure of SLE PBMCs to IFN-α in culture induced massive and sustained A3A levels by 4 h and led to massive cell death. Furthermore, the rs2853669 A > G polymorphism in the telomerase reverse transcriptase (TERT) promoter, which disrupts an Ets-TCF-binding site and influences certain cancers, was highly prevalent in SLE patients, possibly contributing to lymphopenia. Taken together, these findings suggest that high baseline A3A and A3B levels may contribute to cell frailty, lymphopenia and to the generation of neoantigens in SLE patients. Targeting A3 expression could be a strategy to reverse cell death and the generation of neoantigens.

Type I Interferonopathies in Children: An Overview

Notable advances in gene sequencing methods in recent years have permitted enormous progress in the phenotypic and genotypic characterization of autoinflammatory syndromes. Interferonopathies are a recent group of inherited autoinflammatory diseases, characterized by a dysregulation of the interferon pathway, leading to constitutive upregulation of its activation mechanisms or downregulation of negative regulatory systems. They are clinically heterogeneous, but some peculiar clinical features may lead to suspicion: a familial "idiopathic" juvenile arthritis resistant to conventional treatments, an early necrotizing vasculitis, a non-infectious interstitial lung disease, and a panniculitis associated or not with a lipodystrophy may represent the "interferon alarm bells." The awareness of this group of diseases represents a challenge for pediatricians because, despite being rare, a differential diagnosis with the most common childhood rheumatological and immunological disorders is mandatory. Furthermore, the characterization of interferonopathy molecular pathogenetic mechanisms is allowing important steps forward in other immune dysregulation diseases, such as systemic lupus erythematosus and inflammatory myositis, implementing the opportunity of a more effective target therapy.

Salivary Cytokines as Potential Diagnostic Biomarkers for Systemic Lupus Erythematosus Disease

Systemic lupus erythematosus (SLE) is a complex autoimmune inflammatory disease characterized by an unknown etiology and a highly variable clinical presentation. This clinical heterogeneity might be explained by dysregulation of tolerance to self and apoptotic mechanisms, overproduction of autoantibodies, and abnormal cytokine levels. Cytokine imbalance levels have been associated with disease activity and severity in SLE patients. In the last years, salivary cytokines related to SLE have gained significant attention and researchers have begun to focus on the identification of cytokines in the saliva of SLE patients using it as a diagnostic fluid for the inflammatory process underlying SLE. This review highlights and summarizes recent studies revealing the cytokines that have been identified in the saliva of individuals with SLE. Data reported and discussed in this report may provide useful additional information to better understand the mechanisms associated with the disease.

Systemic diseases and the cornea

There is a number of systemic diseases affecting the cornea. These include endocrine disorders (diabetes, Graves' disease, Addison's disease, hyperparathyroidism), infections with viruses (SARS-CoV-2, herpes simplex, varicella zoster, HTLV-1, Epstein-Barr virus) and bacteria (tuberculosis, syphilis and Pseudomonas aeruginosa), autoimmune and inflammatory diseases (rheumatoid arthritis, Sjögren's syndrome, lupus erythematosus, gout, atopic and vernal keratoconjunctivitis, multiple sclerosis, granulomatosis with polyangiitis, sarcoidosis, Cogan's syndrome, immunobullous diseases), corneal deposit disorders (Wilson's disease, cystinosis, Fabry disease, Meretoja's syndrome, mucopolysaccharidosis, hyperlipoproteinemia), and genetic disorders (aniridia, Ehlers-Danlos syndromes, Marfan syndrome). Corneal manifestations often provide an insight to underlying systemic diseases and can act as the first indicator of an undiagnosed systemic condition. Routine eye exams can bring attention to potentially life-threatening illnesses. In this review, we provide a fairly detailed overview of the pathologic changes in the cornea described in various systemic diseases and also discuss underlying molecular mechanisms, as well as current and emerging treatments.

Novel signatures associated with systemic lupus erythematosus clinical response to IFN-α/-ω inhibition

OBJECTIVES

We aimed to identify transcriptional gene signatures predictive of clinical response, for pharmacodynamic evaluation, and to provide mechanistic insight into JNJ-55920839, a human IgG1κ neutralizing mAb targeting IFN-α/IFN-ω, in participants with systemic lupus erythematosus (SLE).

METHODS

Blood samples were obtained from SLE participants at baseline and up to Day 130, who received six 10 mg/kg IV doses of JNJ-55920839/placebo every 2 weeks. Participants with mild-to-moderate SLE who achieved clinical responses using SLE Disease Activity Index 2000 Responder Index 4-point change were considered responders. Transcriptional signatures from longitudinally collected blood were generated by RNA-Seq; signatures were generated by microarray from baseline blood samples exposed in vitro to JNJ-55920839 versus untreated.

RESULTS

Two gene signatures (IFN-I Signaling and Immunoglobulin Immune Response) exhibited pharmacodynamic changes among JNJ-55920839 responders. The Immunoglobulin signature, but not the IFN-I signature, was elevated at baseline in JNJ-55920839 responders. A gene cluster associated with neutrophil-mediated immunity was reduced at baseline in JNJ-55920839 responders, substantiated by lower neutrophil counts in responders. An IFN-I signature was suppressed by JNJ-55920839 in vitro treatment versus untreated blood to a greater extent in responders before in vivo dosing.

CONCLUSIONS

These signatures may enable enrichment for treatment responders when using IFN-I-suppressing treatments in SLE.

Toll-like receptor 7 deficiency suppresses type 1 diabetes development by modulating B-cell differentiation and function

Innate immunity mediated by Toll-like receptors (TLRs), which can recognize pathogen molecular patterns, plays a critical role in type 1 diabetes development. TLR7 is a pattern recognition receptor that senses single-stranded RNAs from viruses and host tissue cells; however, its role in type 1 diabetes development remains unclear. In our study, we discovered that Tlr7-deficient (Tlr7-/-) nonobese diabetic (NOD) mice, a model of human type 1 diabetes, exhibited a significantly delayed onset and reduced incidence of type 1 diabetes compared with Tlr7-sufficient (Tlr7+/+) NOD mice. Mechanistic investigations showed that Tlr7 deficiency significantly altered B-cell differentiation and immunoglobulin production. Moreover, Tlr7-/- NOD B cells were found to suppress diabetogenic CD4+ T-cell responses and protect immunodeficient NOD mice from developing diabetes induced by diabetogenic T cells. In addition, we found that Tlr7 deficiency suppressed the antigen-presenting functions of B cells and inhibited cytotoxic CD8+ T-cell activation by downregulating the expression of both nonclassical and classical MHC class I (MHC-I) molecules on B cells. Our data suggest that TLR7 contributes to type 1 diabetes development by regulating B-cell functions and subsequent interactions with T cells. Therefore, therapeutically targeting TLR7 may prove beneficial for disease protection.

Bite of the wolf: innate immune responses propagate autoimmunity in lupus

The etiopathogenesis of systemic lupus erythematosus (SLE), a clinically heterogeneous multisystemic syndrome that derives its name from the initial characterization of facial lesions that resemble the bite of a wolf, is considered a complex, multifactorial interplay between underlying genetic susceptibility factors and the environment. Prominent pathogenic factors include the induction of aberrant cell death pathways coupled with defective cell death clearance mechanisms that promote excessive externalization of modified cellular and nuclear debris with subsequent loss of tolerance to a wide variety of autoantigens and innate and adaptive immune dysregulation. While abnormalities in adaptive immunity are well recognized and are key to the pathogenesis of SLE, recent findings have emphasized fundamental roles of the innate immune system in the initiation and propagation of autoimmunity and the development of organ damage in this disease. This Review focuses on recent discoveries regarding the role of components of the innate immune system, specifically neutrophils and interferons, in promoting various aspects of lupus pathogenesis, with potential implications for novel therapeutic strategies.

Extracellular Vesicles in Rheumatoid Arthritis and Systemic Lupus Erythematosus: Functions and Applications

In the last two decades, extracellular vesicles (EVs) have aroused wide interest among researchers in basic and clinical research. EVs, small membrane vesicles are released by almost all kinds of cells into the extracellular environment. According to many recent studies, EVs participate in immunomodulation and play an important role in the pathogenesis of autoimmune diseases. In addition, EVs have great potential in the diagnosis and therapy of autoimmune diseases. Here, we reviewed the latest research advances on the functions and mechanisms of EVs and their roles in the pathogenesis, diagnosis, and treatment of rheumatoid arthritis and systemic lupus erythematosus.

Modulation of TCR Signaling by Tyrosine Phosphatases: From Autoimmunity to Immunotherapy

Early TCR signaling is dependent on rapid phosphorylation and dephosphorylation of multiple signaling and adaptor proteins, leading to T cell activation. This process is tightly regulated by an intricate web of interactions between kinases and phosphatases. A number of tyrosine phosphatases have been shown to modulate T cell responses and thus alter T cell fate by negatively regulating early TCR signaling. Mutations in some of these enzymes are associated with enhanced predisposition to autoimmunity in humans, and mouse models deficient in orthologous genes often show T cell hyper-activation. Therefore, phosphatases are emerging as potential targets in situations where it is desirable to enhance T cell responses, such as immune responses to tumors. In this review, we summarize the current knowledge about tyrosine phosphatases that regulate early TCR signaling and discuss their involvement in autoimmunity and their potential as targets for tumor immunotherapy.

Functionally impaired plasmacytoid dendritic cells and non-haematopoietic sources of type I interferon characterize human autoimmunity

Autoimmune connective tissue diseases arise in a stepwise fashion from asymptomatic preclinical autoimmunity. Type I interferons have a crucial role in the progression to established autoimmune diseases. The cellular source and regulation in disease initiation of these cytokines is not clear, but plasmacytoid dendritic cells have been thought to contribute to excessive type I interferon production. Here, we show that in preclinical autoimmunity and established systemic lupus erythematosus, plasmacytoid dendritic cells are not effector cells, have lost capacity for Toll-like-receptor-mediated cytokine production and do not induce T cell activation, independent of disease activity and the blood interferon signature. In addition, plasmacytoid dendritic cells have a transcriptional signature indicative of cellular stress and senescence accompanied by increased telomere erosion. In preclinical autoimmunity, we show a marked enrichment of an interferon signature in the skin without infiltrating immune cells, but with interferon-κ production by keratinocytes. In conclusion, non-hematopoietic cellular sources, rather than plasmacytoid dendritic cells, are responsible for interferon production prior to clinical autoimmunity.

Type I interferon in the pathogenesis of systemic lupus erythematosus

Type I interferon (IFN) is a primary pathogenic factor in systemic lupus erythematosus (SLE). Gain-of-function genetic variants in the type I IFN pathway have been associated with risk of disease. Common polygenic as well as rare monogenic influences on type I IFN have been demonstrated, supporting a complex genetic basis for high IFN in many SLE patients. Both SLE-associated autoantibodies and high type I IFN can be observed in the pre-disease state. Patients with SLE and evidence of high type I IFN have more active disease and a greater propensity to nephritis and other severe manifestations. Despite the well-established association between type I IFN and SLE, the specific triggers of type I IFN production, the mechanisms by which IFNs help perpetuate the cycle of autoreactive cells and autoantibody production are not completely clear. This review provides an updated overview of type I IFN in SLE pathogenesis, clinical manifestations, and current therapeutic strategies targeting this pathway.

The Network of Inflammatory Mechanisms in Lupus Nephritis

Several signaling pathways are involved in the progression of kidney disease in humans and in animal models, and kidney disease is usually due to the sustained activation of these pathways. Some of the best understood pathways are specific proinflammatory cytokine and protein kinase pathways (e.g., protein kinase C and mitogen-activated kinase pathways, which cause cell proliferation and fibrosis and are associated with angiotensin II) and transforming growth factor-beta (TGF-β) signaling pathways (e.g., the TGF-β signaling pathway, which leads to increased fibrosis and kidney scarring. It is thus necessary to continue to advance our knowledge of the pathogenesis and molecular biology of kidney disease and to develop new treatments. This review provides an update of important findings about kidney diseases (including diabetic nephropathy, lupus nephritis, and vasculitis, i.e., vasculitis with antineutrophilic cytoplasmic antibodies). New disease targets, potential pathological pathways, and promising therapeutic approaches from basic science to clinical practice are presented, and the blocking of JAK/STAT and TIM-1/TIM-4 signaling pathways as potential novel therapeutic agents in lupus nephritis is discussed.

The Contribution of Genetics and Epigenetics to Our Understanding of Health Disparities in Rheumatic Diseases

Socioeconomic determinants of health are associated with worse outcomes in the rheumatic diseases and contribute significantly to health disparities. However, genetic and epigenetic risk factors may affect different populations disproportionally and further exacerbate health disparities. We discuss the role of genetics and epigenetics to the health disparities observed in rheumatic diseases. We review concepts of population genetics and natural selection, current genome-wide genetic and epigenetic studies of several autoimmune diseases, and environmental exposures associated with disease risk in different populations. To understand how genomics influence health disparities in the rheumatic diseases, further studies in different populations worldwide are needed.

Pharmacokinetics and Pharmacodynamics of JNJ-55920839, an Antibody Targeting Interferon α/ω, in Healthy Subjects and Subjects with Mild-to-Moderate Systemic Lupus Erythematosus

BACKGROUND

The interferon (IFN) pathway has been correlated with clinical and serological markers of disease activity in patients with systemic lupus erythematosus (SLE).

OBJECTIVE

The pharmacokinetics and pharmacodynamics of JNJ-55920839, a fully human immunoglobulin G1κ antibody targeting IFNα/ω, were investigated.

METHODS

In a double-blind, first-in-human study, Part A enrolled 48 healthy adults who received a single dose of placebo/JNJ-55920839 between 0.3 and 15 mg/kg intravenous (IV) or at 1 mg/kg subcutaneous (SC). Part B enrolled 26 adults with SLE who received placebo or JNJ-55920839 10 mg/kg IV 6 times biweekly. Pharmacokinetic parameters were calculated by noncompartmental analysis (NCA) and estimated by nonlinear mixed-effects modeling.

RESULTS

JNJ-55920839 pharmacokinetics following a single IV infusion exhibited a biphasic disposition in healthy subjects. Maximum plasma concentration (C_max) and area under the concentration-time curve values increased dose-proportionally. Mean clearance (CL) after a single IV infusion ranged between 2.28 and 3.09 mL/kg/day. Absolute bioavailability after a single SC injection was ≥ 80.0%. Mean terminal elimination half-life (t_1/2) was similar after IV (20.7 to 24.6 days) and SC administration (22.6 days). Steady state of JNJ-55920839 was achieved 6 weeks after multiple 10 mg/kg IV doses in subjects with SLE. Mean steady-state CL and t_1/2 were 4.73 mL/kg/day and 14.8 days, respectively. A linear 2-compartment population pharmacokinetic model with 1st-order absorption and elimination adequately characterized the pharmacokinetics; parameters were consistent with NCA estimates. Higher CL was estimated in subjects with SLE compared with healthy subjects, after correcting for body weight. A trend of increased total IFNα/ω levels was observed after treatment with JNJ-55920839.

CONCLUSION

Pharmacokinetic and pharmacodynamic analyses of the data from this study demonstrated that there was biphasic disposition in both healthy subjects and subjects with SLE, CL was faster in subjects with SLE, and increases in total IFNα/ω levels were observed in both healthy subjects and subjects with SLE after treatment with JNJ-55920839, thus further development is supported. The study is registered at ClinicalTrials.gov NCT02609789.

Biological and Clinical Changes in a Pediatric Series Treated with Off-Label JAK Inhibitors

Off-label use of medications is still a common practice in pediatric rheumatology. JAK inhibitors are authorized in adults in the treatment of rheumatoid arthritis, psoriatic arthritis and ulcerative colitis. Although their use is not authorized yet in children, JAK inhibitors, based on their mechanism of action and on clinical experiences in small series, have been suggested to be useful in the treatment of pediatric interferon-mediated inflammation. Accordingly, an increased interferon score may help to identify those patients who might benefit of JAK inhibitors. We describe the clinical experience with JAK inhibitors in seven children affected with severe inflammatory conditions and we discuss the correlation between clinical features and transcriptomic data. Clinical improvements were recorded in all cases. A reduction of interferon signaling was recorded in three out of seven subjects at last follow-up, irrespectively from clinical improvements. Other signal pathways with significant differences between patients and controls included upregulation of DNA repair pathway and downregulation of extracellular collagen homeostasis. Two patients developed drug-related adverse events, which were considered serious in one case. In conclusion, JAK inhibitors may offer a valuable option for children with severe interferon-mediated inflammatory disorders reducing the interferon score as well as influencing other signal pathways that deserve future studies.

Increased MLKL mRNA level in the PBMCs is correlated with autoantibody production, renal involvement, and SLE disease activity

Background

Necroptosis is a form of regulated necrosis that is involved in various autoimmune diseases. Mixed lineage kinase domain-like pseudokinase (MLKL) has been identified as a key executor of necroptosis; however, the significance of MLKL in peripheral blood mononuclear cells (PBMCs) of systemic lupus erythematosus (SLE) has not been investigated. In this study, we aimed to determine the mRNA level of MLKL in PBMCs and examine its relationship with clinical features and serological parameters in SLE.

Methods

Real-time transcription-polymerase chain reaction (RT-PCR) analysis was used to determine the expression of MLKL mRNA in PBMCs from 59 patients with SLE, 25 patients with rheumatoid arthritis (RA), and 30 age- and sex-matched healthy controls (HC). Spearman’s correlation test was performed to assess the correlation of MLKL mRNA with clinical variables. The receiver operating characteristic (ROC) curve was created to evaluate the diagnostic value.

Results

Our results showed MLKL mRNA in PBMCs was upregulated in SLE patients compared to that in RA and HC individuals. SLE patients positive for antinuclear antibodies had significantly higher MLKL mRNA than antibody-negative patients. In SLE patients, MLKL mRNA was found to be upregulated in patients with lupus nephritis (LN) as compared with patients without LN, and also higher in active patients than in stable patients. MLKL mRNA level was significantly and positively correlated with c-reaction protein (CRP) (r = 0.3577, p = 0.0237), erythrocyte sedimentation rate (ESR) (r = 0.4091, p = 0.0043), serum immunoglobulin G (IgG) concentration (r = 0.3546, p = 0.0289), and the numbers of positive antinuclear antibodies (ANAs) (r = 0.3945, p = 0.0432). ROC analysis showed that MLKL mRNA in PBMCs had an area under the curve of 0.9277 (95% CI 0.8779–0.9775, p < 0.001) to discriminate SLE from controls.

Conclusions

These results suggest that increased MLKL mRNA level in the PBMCs of SLE patients is correlated with renal involvement and disease activity, identifying a subgroup of patients with SLE or LN who may benefit from early diagnosis and therapies targeting MLKL.

First-in-Human study of JNJ-55920839 in healthy volunteers and patients with systemic lupus erythematosus: a randomised placebo-controlled phase 1 trial

BACKGROUND

Activation of the type I interferon (IFN) pathway is associated with systemic lupus erythematosus (SLE). We assessed the safety and tolerability of JNJ-55920839, a human monoclonal antibody that selectively neutralises most human IFNα subtypes and IFNω, in healthy participants and those with SLE.

METHODS

This was a two-part, first-in-human, phase 1, randomised, double-blind, placebo-controlled, multicentre study of single-ascending intravenous doses of 0·3-15 mg/kg or a single subcutaneous dose of 1 mg/kg JNJ-55920839 administered to healthy participants (part A) and multiple intravenous doses of 10 mg/kg JNJ-55920839 administered to participants with SLE (part B). Healthy men and women (women had to be postmenopausal or surgically sterile) aged 18-55 years; bodyweight of 50-90 kg; and body-mass index (BMI) of 18-30 kg/m2 were eligible for inclusion in part A. Men and women with SLE were recruited to part B, fertile female participants were required to have a negative pregnancy test result before and during the study and be using two highly effective methods of birth control. The inclusion criteria for participants with SLE in part B matched part A, except for bodyweight (40-100 kg). In both parts, participants were randomly assigned (3:1) to receive JNJ-55920839 or placebo; a computer-generated randomisation schedule was used in part A, and randomisation was stratified by racial and ethnic subpopulation and elevated levels of serological disease activity in part B. The primary outcome was evaluation of safety and tolerability of the study regimen assessed using clinical and laboratory tests compared with placebo. This study is registered with ClinicalTrials.gov, NCT02609789.

FINDINGS

Between Dec 11, 2015, and Sept 20, 2018, 48 healthy participants from a single site and 28 participants with mild-to-moderate SLE from 19 participating centres in seven countries were enrolled in the study. 12 healthy volunteers in part A and eight participants with SLE in part B received placebo. The most common treatment-emergent adverse events in both part A and B were in the system organ class of infections and infestations with a higher percentage of participants administered JNJ-55920839 with infections (ten [28%] of 36 in part A and nine [50%] of 18 in part B) than those exposed to placebo (two [17%] of 12 in part A and one [13%] of eight in part B). Particpants in part B were permitted to continue on defined ongoing standard of care medications. In two participants with SLE, locally disseminated herpes zoster of the skin was reported. No other clinically significant safety or tolerability issues were identified beyond the infections observed in participants treated with JNJ-55920839.

INTERPRETATION

JNJ-55920839 was well tolerated and safe. Additional studies are warranted to determine optimal dosing of patients and further explore safety.

FUNDING

Janssen.

Type I interferon antagonists in clinical development for lupus

INTRODUCTION

Systemic lupus erythematosus (SLE) is a severe chronic and incurable autoimmune disease. Treatment includes glucocorticoids and immunosuppressants which typically result in partial responses, and hence there is a great need for new therapies. The type I interferon (IFN) pathway is activated in more than 50% of SLE patients, and it is strongly implicated as a pathogenic factor in SLE.

AREAS COVERED

We searched the literature using 'SLE and interferon antagonists' as search terms. This identified a number of therapeutics that have entered clinical development targeting type I IFN in SLE. These include monoclonal antibodies against type I IFN cytokines and a kinoid vaccination strategy to induce anti-IFN antibodies.

EXPERT OPINION

Type I IFN antagonists have had some success, but many molecules have not progressed to phase III. These varied results are likely attributed to the multiple concurrent cytokine abnormalities present in SLE, the imprecise nature of the IFN signature as a readout for type I IFN and difficulties with clinical trials such as background medication use and diffuse composite disease activity measures. Despite these challenges, it seems likely that a type I IFN antagonist will come to clinical utility for SLE given the large unmet need and the recent phase III success with anifrolumab.

An Update on the Pathogenesis of Cutaneous Lupus Erythematosus and Its Role in Clinical Practice

PURPOSE OF REVIEW

Understanding the pathogenesis of cutaneous lupus erythematosus (CLE) is an important step in developing new medications and providing effective treatment to patients. This review focuses on novel research within CLE pathogenesis, as well as some of the medications being developed based on this knowledge.

RECENT FINDINGS

The subtle differences between systemic lupus erythematosus (SLE) and CLE pathogenesis are highlighted by differences in the circulating immune cells found in each disease, as well as the specific pathways activated by ultraviolet light. Plasmacytoid dendritic cells and the related type I interferon pathway are major components of CLE pathogenesis, and as such, therapies targeting components of this pathway have been successful in recent clinical trials. B cell-depleting therapies have shown success in SLE; however, their role in CLE is less clear. Understanding the differences between these manifestations of lupus allows for the development of therapies that are more effective in skin-specific disease. Discovering key pathways in CLE pathogenesis is critical for understanding the clinical features of the disease and ultimately developing new and effective therapies.

Patient ancestry significantly contributes to molecular heterogeneity of systemic lupus erythematosus

Gene expression signatures can stratify patients with heterogeneous diseases, such as systemic lupus erythematosus (SLE), yet understanding the contributions of ancestral background to this heterogeneity is not well understood. We hypothesized that ancestry would significantly influence gene expression signatures and measured 34 gene modules in 1566 SLE patients of African ancestry (AA), European ancestry (EA), or Native American ancestry (NAA). Healthy subject ancestry-specific gene expression provided the transcriptomic background upon which the SLE patient signatures were built. Although standard therapy affected every gene signature and significantly increased myeloid cell signatures, logistic regression analysis determined that ancestral background significantly changed 23 of 34 gene signatures. Additionally, the strongest association to gene expression changes was found with autoantibodies, and this also had etiology in ancestry: the AA predisposition to have both RNP and dsDNA autoantibodies compared with EA predisposition to have only anti-dsDNA. A machine learning approach was used to determine a gene signature characteristic to distinguish AA SLE and was most influenced by genes characteristic of the perturbed B cell axis in AA SLE patients.

Transcriptional profiling of lupus patients and healthy controls reveals ancestry-related differences and transcriptional heterogeneity among lupus patients.

Novel genetic associations with interferon in systemic lupus erythematosus identified by replication and fine-mapping of trait-stratified genome-wide screen

BACKGROUND/PURPOSE

High serum interferon alpha (IFN-α) is an important heritable phenotype in systemic lupus erythematosus (SLE) which is involved in primary disease pathogenesis. High vs. low levels of IFN-α are associated with disease severity and account for some of the biological heterogeneity between SLE patients. The aim of the study was to replicate and fine-map previously detected genetic associations with serum IFN-α in SLE.

METHODS

We previously undertook a case-case genome-wide association study of SLE patients stratified by ancestry and extremes of phenotype in serum IFN-α. Single nucleotide polymorphisms (SNPs) in seven loci identified in this screen were selected for follow up in a large independent cohort of 1370 SLE patients (703 European-ancestry, 432 African ancestry, and 235 Amerindian ancestry). Each ancestral background was analyzed separately, and ancestry-informative markers were used to control for ancestry and admixture.

RESULTS

We find a rare haplotype spanning the promoter region of EFNA5 that is strongly associated with serum IFN-α in both African-American and European-American SLE patients (OR = 3.0, p = 3.7 × 10-6). We also find SNPs in the PPM1H, PTPRM, and NRGN regions associated with IFN-α levels in European-American, Amerindian, and African-American SLE patients respectively. Many of these associations are within regulatory regions of the gene, suggesting an impact on transcription.

CONCLUSION

This study demonstrates the power of molecular sub-phenotypes to reveal genetic factors involved in complex autoimmune disease. The distinct associations observed in different ancestral backgrounds emphasize the heterogeneity of molecular pathogenesis in SLE.

Distinct Single Cell Gene Expression in Peripheral Blood Monocytes Correlates With Tumor Necrosis Factor Inhibitor Treatment Response Groups Defined by Type I Interferon in Rheumatoid Arthritis

Previously, we demonstrated in test and validation cohorts that type I IFN (T1IFN) activity can predict non-response to tumor necrosis factor inhibitors (TNFi) in rheumatoid arthritis (RA). In this study, we examine the biology of non-classical and classical monocytes from RA patients defined by their pre-biologic treatment T1IFN activity. We compared single cell gene expression in purified classical (CL, n = 342) and non-classical (NC, n = 359) monocytes. In our previous work, RA patients who had either high IFNβ/α activity (>1.3) or undetectable T1IFN were likely to have EULAR non-response to TNFi. In this study comparisons were made among patients grouped according to their pre-biologic treatment T1IFN activity as clinically relevant: “T1IFN undetectable (T1IFN ND) or IFNβ/α >1.3” (n = 9) and “T1IFN detectable but IFNβ/α ≤ 1.3” (n = 6). In addition, comparisons were made among patients grouped according to their T1IFN activity itself: “T1IFN ND,” “T1IFN detected and IFNβ/α ≤ 1.3,” and “IFNβ/α >1.3.” Major differences in gene expression were apparent in principal component and unsupervised cluster analyses. CL monocytes from the T1IFN ND or IFNβ/α >1.3 group were unlikely to express JAK1 and IFI27 (p < 0.0001 and p 0.0005, respectively). In NC monocytes from the same group, expression of IFNAR1, IRF1, TNFA, TLR4 (p ≤ 0.0001 for each) and others was enriched. Interestingly, JAK1 expression was absent in CL and NC monocytes from nine patients. This pattern most strongly associated with the IFNβ/α>1.3 group. Differences in gene expression in monocytes among the groups suggest differential IFN pathway activation in RA patients who are either likely to respond or to have no response to TNFi. Additional transcripts enriched in NC cells of those in the T1IFN ND and IFNβ/α >1.3 groups included MYD88, CD86, IRF1, and IL8. This work could suggest key pathways active in biologically defined groups of patients, and potential therapeutic strategies for those patients unlikely to respond to TNFi.

An Update on the Pathogenesis of Skin Damage in Lupus

PURPOSE OF REVIEW

Lupus erythematosus (LE) is characterized by broad and varied clinical forms ranging from a localized skin lesion to a life-threatening form with severe systemic manifestations. The overlapping between cutaneous LE (CLE) and systemic LE (SLE) brings difficulties to physicians for early accurate diagnosis and sometimes may lead to delayed treatment for patients. We comprehensively review recent progress about the similarities and differences of the main three subsets of LE in pathogenesis and immunological mechanisms, with a particular focus on the skin damage.

RECENT FINDINGS

Recent studies on the mechanisms contributing to the skin damage in lupus have shown a close association of abnormal circulating inflammatory cells and abundant production of IgG autoantibodies with the skin damage of SLE, whereas few evidences if serum autoantibodies and circulating inflammatory cells are involved in the pathogenesis of CLE, especially for the discoid LE (DLE). Till now, the pathogenesis and molecular/cellular mechanism for the progress from CLE to SLE are far from clear. But more and more factors correlated with the differences among the subsets of LE and progression from CLE to SLE have been found, such as the mutation of IRF5, IFN regulatory factors and abnormalities of plasmacytoid dendritic cells (PDCs), Th1 cells, and B cells, which could be the potential biomarkers for the interventions in the development of LE. A further understanding in pathogenesis and immunological mechanisms for skin damage in different subsets of LE makes us think more about the differences and cross-links in the pathogenic mechanism of CLE and SLE, which will shed a light in predictive biomarkers and therapies in LE.

Anifrolumab in systemic lupus erythematosus: current knowledge and future considerations

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that is potentially life-threatening and can affect any organ. The complex pathogenesis and heterogeneity of the disease, among other factors, present significant challenges in developing new therapies. Knowledge gained over many years has implicated type I interferon (IFN) in the pathogenesis of SLE and anti-IFN therapies hold promise as a much-needed future treatment for SLE. Anifrolumab, a human monoclonal antibody against the type I IFN receptor, has recently been evaluated in two Phase III clinical trials for the treatment of moderate-to-severe SLE. Here, we review the clinical efficacy and safety of anifrolumab and discuss the potential challenges in determining the optimal SLE patient subgroup for treatment.

Differential Responsiveness of Monocyte and Macrophage Subsets to Interferon

OBJECTIVE

Peripheral blood mononuclear cells (PBMCs) in systemic lupus erythematosus (SLE) patients exhibit a gene expression program (interferon [IFN] signature) that is attributed to overproduction of type I IFNs by plasmacytoid dendritic cells. Type I IFNs have been thought to play a role in the pathogenesis of SLE. This study was undertaken to examine an unexpected influence of monocyte/macrophages on the IFN signature.

METHODS

Proinflammatory (classic) and antiinflammatory (nonclassic) monocyte/macrophages were sorted from mice and analyzed by RNA sequencing and quantitative polymerase chain reaction (qPCR). Type I IFN-α/β/ω receptor (IFNAR-1) expression was determined by qPCR and flow cytometry. Macrophages were stimulated in vitro with IFNα, and pSTAT1was measured.

RESULTS

Transcriptional profiling of peritoneal macrophages from mice with pristane-induced SLE unexpectedly indicated a strong IFN signature in classic, but not nonclassic, monocyte/macrophages exposed to the same type I IFN concentrations. Ifnar1 messenger RNA and IFNAR surface staining were higher in classic monocyte/macrophages versus nonclassic monocyte/macrophages (P < 0.0001 and P < 0.05, respectively, by Student's t-test). Nonclassic monocyte/macrophages were also relatively insensitive to IFNα-driven STAT1 phosphorylation. Humans exhibited a similar pattern: higher IFNAR expression (P < 0.0001 by Student's t-test) and IFNα-stimulated gene expression (P < 0.01 by paired Wilcoxon's rank sum test) in classic monocyte/macrophages and lower levels in nonclassic monocyte/macrophages.

CONCLUSION

This study revealed that the relative abundance of different monocyte/macrophage subsets helps determine the magnitude of the IFN signature. Responsiveness to IFNα signaling reflects differences in IFNAR expression in classic (high IFNAR) compared to nonclassic (low IFNAR) monocyte/macrophages. Thus, the IFN signature depends on both type I IFN production and the responsiveness of monocyte/macrophages to IFNAR signaling.

Design and validation of an immuno-PCR assay for IFN-α2b quantification in human plasma

Aim: Nowadays, IFN-α is considered a promising therapeutic target for systemic lupus erythematosus. An immuno-PCR (iPCR) was developed to quantify low amounts of IFN-α in human plasma followed by a deep analysis of the methodologic robustness throughout quality by design approach. Results: An accurate, sensitive, selective and versatile iPCR was validated. The critical iPCR procedural steps were identified, applying a Plackett–Burman design. Also, this assay demonstrated an outstanding LOD of 0.3 pg/ml. A significant aspect relies on its high versatility to detect and quantify other cytokines in human plasma as the appropriate biotinylated antibody is employed. Conclusion: This reliable iPCR assay can be clinically used as an alternative method for quantitating and detecting low IFN-α2b concentrations in human plasma samples.

Ultrasensitive serum interferon-α quantification during SLE remission identifies patients at risk for relapse

OBJECTIVES

Maintenance of remission has become central in the management of systemic lupus erythematosus (SLE). The importance of interferon-alpha (IFN-α) in the pathogenesis of SLE notwithstanding, its expression in remission has been poorly studied as yet. To study its expression in remission and its prognostic value in the prediction of a disease relapse, serum IFN-α levels were determined using an ultrasensitive single-molecule array digital immunoassay which enables the measurement of cytokines at physiological concentrations.

METHODS

A total of 254 SLE patients in remission, according to the Definition of Remission in SLE classification, were included in the study. Serum IFN-α concentrations were determined at baseline and patients were followed up for 1 year. Lupus flares were defined according to the Safety of Estrogens in Lupus Erythematosus: National Assessment version of the Systemic Lupus Erythematosus Disease Activity Index Flare Index, whereas the Kaplan-Meier analysis and Cox regression analysis were used to estimate the time to relapse and to identify baseline factors associated with time to relapse, respectively.

RESULTS

Of all patients in remission, 26% displayed abnormally high IFN-α serum levels that were associated with the presence of antibodies specific for ribonucleoprotein (RNP), double stranded (ds)DNA and Ro/SSA60, as well as young age. Importantly, elevated-baseline IFN-α serum levels and remission duration were associated in an independent fashion, with shorter time to relapse, while low serum levels of complement component 3 and anti-dsDNA Abs were not.

CONCLUSION

Direct serum IFN-α assessment with highly sensitive digital immunoassay permits clinicians to identify a subgroup of SLE patients, clinically in remission, but at higher risk of relapse.

IFNα Impairs Autophagic Degradation of mtDNA Promoting Autoreactivity of SLE Monocytes in a STING-Dependent Fashion

Interferon α (IFNα) is a prompt and efficient orchestrator of host defense against nucleic acids but upon chronicity becomes a potent mediator of autoimmunity. Sustained IFNα signaling is linked to pathogenesis of systemic lupus erythematosus (SLE), an incurable autoimmune disease characterized by aberrant self-DNA sensing that culminates in anti-DNA autoantibody-mediated pathology. IFNα instructs monocytes differentiation into autoinflammatory dendritic cells (DCs) than potentiates the survival and expansion of autoreactive lymphocytes, but the molecular mechanism bridging sterile IFNα-danger alarm with adaptive response against self-DNA remains elusive. Herein, we demonstrate IFNα-mediated deregulation of mitochondrial metabolism and impairment of autophagic degradation, leading to cytosolic accumulation of mtDNA that is sensed via stimulator of interferon genes (STING) to promote induction of autoinflammatory DCs. Identification of mtDNA as a cell-autonomous enhancer of IFNα signaling underlines the significance of efficient mitochondrial recycling in the maintenance of peripheral tolerance. Antioxidant treatment and metabolic rescue of autolysosomal degradation emerge as drug targets in SLE and other IFNα-related pathologies.

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IFNα obstructs autophagic flux in SLE monocytes through lysosomal alkalinization

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IFNα signaling induces oxidative stress that affects lysosomal pH through mTOR

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Impaired clearance of damaged mitochondria leads to cytosolic mtDNA accumulation

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Autophagic escape of mtDNA is sensed by STING and primes monocytes autoimmunity

Autoreactive B cells in SLE, villains or innocent bystanders?

The current concepts for development of autoreactive B cells in SLE (systemic lupus erythematosus) focus on extrinsic stimuli and factors that provoke B cells into tolerance loss. Traditionally, major tolerance loss pathways are thought to be regulated by factors outside the B cell including autoantigen engagement of the B-cell receptor (BCR) with simultaneous type I interferon (IFN) produced by dendritic cells, especially plasmacytoid dendritic cells (pDCs). Later, in autoreactive follicles, B-cells encounter T-follicular helper cells (Tfh) that produce interleukin (IL)-21, IL-4 and pathogenic cytokines, IL-17 and IFN gamma (IFNɣ). This review discusses these mechanisms and also highlights recent advances pointing to the peripheral transitional B-cell stage as a major juncture where transient autocrine IFNβ expression by developing B-cells imprints a heightened susceptibility to external factors favoring differentiation into autoantibody-producing plasmablasts. Recent studies highlight transitional B-cell heterogeneity as a determinant of intrinsic resistance or susceptibility to tolerance loss through the shaping of B-cell responsiveness to cytokines and other environment factors.

IMMUNOINFLAMMATORY RHEUMATIC DISEASES ASSOCIATED WITH TYPE I INTERFERON: NEW EVIDENCE

Immunoinflammatory rheumatic diseases (IIRDs) are a large group of pathological conditions with impaired immunological tolerance to autogenous tissues, leading to inflammation and irreversible organ damage. The review discusses current ideas on the role of type I interferons in the immunopathogenesis of IIRDs, primarily systemic lupus erythematosus, and new possibilities for personalized therapy.

Moving Forward With Biologics in Lupus Nephritis

The majority of patients with systemic lupus erythematosus develop lupus nephritis (LN) which significantly contributes to increased risks of hospitalizations, ESRD, and death. Unfortunately, treatments for LN have not changed over the past 15 years. Despite continued efforts to elucidate the pathogenesis of LN, no new drugs have yet replaced the standard-of-care regimens of cyclophosphamide or mycophenolate mofetil plus high-dose corticosteroids. The significant limitations of standard-of-care are low complete response rates, risk of flares, and ongoing inflammation in the kidney leading to progressive renal dysfunction. Repeat and prolonged treatments are often needed to control disease, leading to a high level of severe side effects. The development of targeted drugs with better efficacy and safety are desperately needed. The rationale for targeting key immunologic pathways in LN continues to be strongly supported by basic and translational research and has generated the hope and excitement of testing these therapies in human LN. This review provides an overview of biologics studied to date in clinical trials of LN, discusses the potential reasons for their failure, and addresses the challenges moving forward.

Type I Interferon Predicts an Alternate Immune System Phenotype in Systemic Lupus Erythematosus

Objective

Type I interferon (IFN) is important to systemic lupus erythematosus (SLE) pathogenesis, but it is not clear how chronic elevations in IFN alter immune function. We compared cytokine responses after whole blood stimulation with Toll‐like receptor (TLR) agonists in high‐ and low‐IFN SLE patient subgroups.

Methods

SLE patients and nonautoimmune controls were recruited, and SLE patients were categorized as either high or low IFN. Whole blood was dispensed into tubes coated with lipopolysaccharide (LPS), oligonucleotides with cytosine‐guanine repeats, Resiquimod, IFN‐α, and IFN‐α + LPS. Cytokine production in patient sera and after whole blood TLR stimulation was measured by multiplex assay, and type I IFN was assessed using a functional assay.

Results

Circulating plasmacytoid dendritic cell numbers were specifically reduced in high‐IFN SLE patients and not in low‐IFN SLE patients. In serum, we observed that the correlations between cytokines in serum differed to a much greater degree between the high‐ and low‐IFN groups (P < 0.0001) than the absolute cytokine levels differed between these same groups. In stimulated conditions, the high‐IFN patients had less cytokine production in response to TLR ligation than the low‐IFN SLE patients. LPS produced the most diverse response, and a number of interactions between type I IFN and LPS were observed.

Conclusion

We find striking differences in resting and stimulated cytokine patterns in high‐ vs. low‐IFN SLE patients, which supports the biological importance of these patient subsets. These data could inform personalized treatment approaches and the pathogenesis of SLE flare following infection.

The cytokine network type I IFN-IL-27-IL-10 is augmented in murine and human lupus

IL-10 is elevated in the autoimmune disease systemic lupus erythematosus (SLE). Here, we show that conventional dendritic cells (cDCs) from predisease lupus-prone B6.NZM Sle1/Sle2/Sle3 triple congenic (TCSle) mice produce more IL-10 than wild-type congenic cDCs upon TLR stimulation, and this overproduction is prevented by blocking the type I IFN receptor (IFNAR) with specific Abs. Priming wild-type cDCs with type I IFN mimics the IL-10 overproduction of TCSle cDCs. The MAPK ERK is more phosphorylated in lupus cDCs, partially contributing to IL-10 overproduction. Moreover, we found that TCSle cDCs express higher levels of IL-27 upon TLR7/TLR9 stimulation, and IFNAR blockade reduced IL-27 levels in TCSle cDCs. These results suggest that dysregulated type I IFNs in cDCs contribute to the increased IL-10 and IL-27 in SLE. Since IL-27 neutralization did not inhibit TLR-induced IL-10 production, we propose that type I IFNs enhanced IL-10 in TCSle cDCs independently from IL-27. Moreover, RNA sequencing analysis of a cohort of SLE patients reveals higher gene expression of these cytokines in SLE patients expressing a high IFN signature. Since IL-27 and IL-10 have both pro- and anti-inflammatory effects, our results also suggest that these cytokines can be modulated by the therapeutic IFN blockade in trials in SLE patients and have complex effects on the autoimmune response.

Metformin Inhibits the Type 1 IFN Response in Human CD4+ T Cells

In systemic lupus erythematosus, defective clearance of apoptotic debris and activation of innate cells result in a chronically activated type 1 IFN response, which can be measured in PBMCs of most patients. Metformin, a widely used prescription drug for Type 2 diabetes, has a therapeutic effect in several mouse models of lupus through mechanisms involving inhibition of oxidative phosphorylation and a decrease in CD4⁺ T cell activation. In this study, we report that in CD4⁺ T cells from human healthy controls and human systemic lupus erythematosus patients, metformin inhibits the transcription of IFN-stimulated genes (ISGs) after IFN-α treatment. Accordingly, metformin inhibited the phosphorylation of pSTAT1 (Y701) and its binding to IFN-stimulated response elements that control ISG expression. These effects were independent of AMPK activation or mTORC1 inhibition but were replicated using inhibitors of the electron transport chain respiratory complexes I, III, and IV. This indicates that mitochondrial respiration is required for ISG expression in CD4⁺ T cells and provides a novel mechanism by which metformin may exert a therapeutic effect in autoimmune diseases.

Familial Aggregation of Childhood- and Adulthood-Onset Systemic Lupus Erythematosus

OBJECTIVE

To assess the familial occurrence of systemic lupus erythematosus (SLE) in a large Brazilian cohort.

METHODS

Consecutive patients with SLE were recruited and stratified according to age at disease onset into childhood-onset SLE or adult-onset SLE. Each patient was personally interviewed regarding the history of SLE across 3 generations (first-, second-, and third-degree relatives). Recurrence rates were analyzed for each degree of relation.

RESULTS

We included 392 patients with SLE (112 with childhood-onset SLE and 280 with adult-onset SLE). We identified 2,574 first-degree relatives, 5,490 second-degree relatives, and 6,805 third-degree relatives. In the combined overall SLE cohort, we observed a familial SLE recurrence rate of 19.4 in first-degree relatives, 5.4 in second-degree relatives, and 3.0 in third-degree relatives. Recurrence rates were higher for first- and second-degree relatives of patients with childhood-onset SLE than for first- and second-degree relatives of patients with adult-onset SLE (25.2 versus 18.4 for first-degree, and 8.5 versus 4.5 for second-degree), while in third-degree relatives, recurrence rates were higher in adult-onset SLE than in childhood-onset SLE (P = 2.2 × 10^-4 for differences in recurrence proportions between childhood-onset SLE and adult-onset SLE). There were no phenotypic differences in patients from multicase versus single-case families, and there was no sex-skewing observed in the offspring of patients with SLE.

CONCLUSION

The greater decline in SLE recurrence rate by generation in childhood-onset SLE versus adult-onset SLE suggests a more polygenic and epistatic inheritance and suggests that adult-onset SLE may be characterized by fewer risk factors that are individually stronger. This finding suggests a higher genetic load in childhood-onset SLE versus adult-onset SLE and a difference in the genetic architecture of the disease based on age at onset.