Endothelial progenitor dysfunction associates with a type I interferon signature in primary antiphospholipid syndrome

Antiphospholipid Antibodies as Key Players in Systemic Lupus Erythematosus: The Relationship with Cytokines and Immune Dysregulation

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by an overproduction of cytokines, such as interleukins and interferons, contributing to systemic inflammation and tissue damage. Antiphospholipid syndrome is a thrombo-inflammatory autoimmune disease affecting a third of SLE patients. We performed an in-depth analysis of the available literature, and we highlighted the complex interplay between immunity, inflammation, and thrombosis, the three major pathogenic pathways that are trapped in a mutually reinforcing destructive loop.

Type I interferon pathway activation across the antiphospholipid syndrome spectrum: associations with disease subsets and systemic antiphospholipid syndrome presentation

Introduction

While the type I interferon (IFN-I) pathway is crucial in autoimmunity, its role in antiphospholipid antibody (aPL)-positive subjects, including aPL carriers and antiphospholipid syndrome (APS) patients, is poorly understood. This study aims at characterizing IFN-I pathway activation within the spectrum of aPL-positive subsets.

Methods

A total of 112 patients [29 aPL carriers, 31 primary APS (PAPS), 25 secondary APS (SAPS), 27 systemic lupus erythematosus (SLE) patients without aPL, and 44 healthy controls (HCs)] were recruited. IFI6, IFI44, IFI44L, MX1, IFI27, OAS1, and RSAD2 gene expression was evaluated in whole blood, and a composite index (IFN score) was calculated.

Results

An overall activation of the IFN-I pathway was observed across the entire APS spectrum, with differences among genes based on the specific disease subset. The composite score revealed quantitative differences across subsets, being elevated in aPL carriers and PAPS patients compared to HCs (both p < 0.050) and increasing in SAPS (p < 0.010) and SLE patients (p < 0.001). An unsupervised cluster analysis identified three clusters, and correspondence analyses revealed differences in clusters usage across APS subsets (p < 0.001). A network analysis revealed different patterns characterizing different subsets. The associations between IFN-I pathway activation and clinical outcomes differed across APS subsets. Although no differences in gene expression were observed in systemic APS, the network analyses revealed specific gene-gene patterns, and a distinct distribution of the clusters previously identified was noted (p = 0.002).

Conclusion

IFN-I pathway activation is a common hallmark among aPL-positive individuals. Qualitative and quantitative differences across the APS spectrum can be identified, leading to the identification of distinct IFN-I signatures with different clinical values beyond traditional categorization.

Non-invasive imaging in antiphospholipid syndrome to assess subclinical coronary artery disease

Antiphospholipid antibody syndrome (usually named antiphospholipid syndrome, APS) is an autoimmune disorder seen mainly in young people. Clinically, APS is described by pregnancy complications and/or a hypercoagulable state, including the venous or arterial vasculature, and strongly related to antiphospholipid antibodies. Although several cardiac manifestations have been involved with APS, and accelerated atherosclerosis is present in this condition, little is known about cardiovascular (CV) risk and the relation between APS. Several studies have used imaging markers to associate them with the main clinical features of patients with APS and the probability of having subclinical atherosclerosis. However, it has not yet been established which markers are most related to the risk of developing CV diseases (CVD) in these patients. In this narrative review, we focus on non-invasive imaging markers that can predict CVD, including carotid intima-media thickness and carotid plaques assessed by carotid ultrasonography or coronary artery calcium score, which usually by computed tomography. We also examine the evidence about vascular function markers used in APS, such as arterial flow-mediated brachial dilation and artery stiffness measured by the velocity of the pulse wave. We present the current status of non-invasive imaging markers, which suggest the existence of subclinical atherosclerosis in patients with APS. However, new prospective research is required to identify the predictive value of these findings and their modification by current treatments for APS.

Anticoagulant and non-anticoagulant therapy in thrombotic antiphospholipid syndrome: old drugs and new treatment targets

In this review, we discuss the current evidence on classic and newer oral anticoagulant therapy, older drugs such as HCQ and statins, and new potential treatment targets in APS. Vitamin K antagonists (VKAs) remain the cornerstone treatment for thrombotic events in APS. In patients fulfilling criteria for definite APS presenting with a first venous thrombosis, treatment with VKAs with a target international normalized ratio (INR) 2.0-3.0 is recommended. In patients with arterial thrombosis, treatment with VKA with target INR 2.0-3.0 or 3.0-4.0 is recommended by recent guidelines, considering the individual's bleeding and thrombosis recurrence risk. A combination of VKAs and low-dose aspirin (75-100 mg/daily) may also be considered. According to available evidence direct oral anticoagulants should be avoided in patients with arterial thrombosis and/or those with triple aPL positivity. Adjunctive treatment with HCQ and/or statins can be considered, especially in anticoagulation treatment-refractory APS. Potential targeted treatments in APS include B-cell targeting, complement inhibition, mammalian target of rapamycin inhibition, IFN targeting, adenosine receptors agonists, CD38 targeting or chimeric antigen receptor T-cell therapy. The safety and efficacy of these treatment targets needs to be examined in well-designed randomized controlled trials.

Proteomics of Serum Samples for the Exploration of the Pathological Mechanism of Obstetric Antiphospholipid Syndrome

Obstetric antiphospholipid syndrome (OAPS) is a multisystem disorder characterized by thrombosis or recurrent fetal loss. In this study, we aim to explore the pathological mechanism of OAPS. Herein, we carried out data-independent acquisition (DIA) mass spectrometry quantitative proteomic analysis of serum samples from OAPS patients and healthy controls. A set of 93 differentially expressed proteins was identified, including 75 upregulated and 18 downregulated proteins compared with the levels in controls. Those proteins are enriched in KEGG pathways related to autoimmune diseases, allergic diseases, and pathogen infection. Interestingly, metabolic pathways such as fatty acid degradation and type I diabetes were enriched, indicating that OAPS is metabolic disease related. The significantly increased triglyceride also supported this idea. The differentially expressed proteins insulin-like growth factor-binding protein-1 (IGFBP-1), C-reactive protein (CRP), and ferritin light chain (FTL) were validated by ELISA. Our study presented a deep serum proteomics of OAPS and advanced our understanding of OAPS pathogenesis.

Endothelial Progenitor Cells in Autoimmune Disorders

Circulating endothelial progenitor cells (EPCs) were first described in 1997 by Asahara et al. as "putative endothelial cells" from human peripheral blood. The study of endothelial progenitors is also intensifying in several pathologies associated with endothelial damage, including diabetes, myocardial infarction, sepsis, pulmonary arterial hypertension, obstructive bronchopneumopathy and transplantation. EPCs have been studied in several autoimmune diseases with endothelial involvement such as systemic lupus erythematosus, thrombotic thrombocytopenic purpura, antineutrophil cytoplasmic antibodies, vasculitis, rheumatoid arthritis, Goujerot-Sjögren and antiphospholipid syndrome. Factors involved in endothelial damage are due to overexpression of pro-inflammatory cytokines and/or autoantibodies. Management of these pathologies, particularly the long-term use of glucocorticoids and methotrexate, promote atherosclerosis. A lack of standardized assessment of the number and function of EPCs represents a serious challenge for the use of EPCs as prognostic markers of cardiovascular diseases (CVD). The objective of this review was to describe EPCs, their properties and their involvement in several autoimmune diseases.

Potentials of Endothelial Colony-Forming Cells: Applications in Hemostasis and Thrombosis Disorders, from Unveiling Disease Pathophysiology to Cell Therapy

Endothelial colony-forming cells (ECFCs) are endothelial progenitor cells circulating in a limited number in peripheral blood. They can give rise to mature endothelial cells (ECs) and, with intrinsically high proliferative potency, contribute to forming new blood vessels and restoring the damaged endothelium in vivo. ECFCs can be isolated from peripheral blood or umbilical cord and cultured to generate large amounts of autologous ECs in vitro. Upon differentiation in culture, ECFCs are excellent surrogates for mature ECs showing the same phenotypic, genotypic, and functional features. In the last two decades, the ECFCs from various vascular disease patients have been widely used to study the diseases' pathophysiology ex vivo and develop cell-based therapeutic approaches, including vascular regenerative therapy, tissue engineering, and gene therapy. In the current review, we will provide an updated overview of past studies, which have used ECFCs to elucidate the molecular mechanisms underlying the pathogenesis of hemostatic disorders in basic research. Additionally, we summarize preceding studies demonstrating the utility of ECFCs as cellular tools for diagnostic or therapeutic clinical applications in thrombosis and hemostasis.

Should we be targeting type 1 interferons in antiphospholipid syndrome?

Systemic autoimmune diseases are characterized by increased production of type I interferon (IFN-1) and upregulation of IFN-1-inducible genes, suggesting an important role of the IFN-1 pathway in their pathogenesis. Recent studies have demonstrated increased IFN-1 expression in both primary and secondary antiphospholipid syndrome (APS), along with increased toll-like receptor type 9 activity and plasmacytoid dendritic cell function. The increasing knowledge of the association between IFN-1 and APS pathology may provide a rationale for conducting clinical trials to assess the efficacy of IFN-1-targeting drugs in reducing APS-related complications. In this narrative review, we summarize the current knowledge on the role of IFN-1 in APS pathogenesis, explore its clinical implications, and examine the existing evidence regarding therapeutic options that have been investigated to date.

Antiphospholipid syndrome nephropathy: Current knowledge and unanswered questions

The definition of acute and chronic antiphospholipid syndrome (APS) nephropathy was recently updated using a multiphase methodology in the context of the development of the new APS classification criteria. Currently, there is no consensus for the treatment of APS nephropathy, which mainly relies on the general recommendations for the management of APS. Based on evidence from experimental studies and a few clinical studies and case series, targeted treatments such as B-cell depletion, anti-B-cell activating factor antibody, complement inhibition, mammalian target of rapamycin inhibition, and neutrophil extracellular traps or interferon targeting may show promise for the treatment of microvascular manifestations in APS, including APS nephropathy. Validation of the new APS nephropathy definition and/or efforts for improvement in proposed terminology, along with the assessment of the safety and efficacy of potential targeted treatments in randomized controlled trials, are major future research directions. In this review, we summarize the current knowledge of APS nephropathy and discuss unanswered questions.

Augmented oxidative stress, accumulation of DNA damage and impaired DNA repair mechanisms in thrombotic primary antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a rare autoimmune disorder with complex pathogenesis. Studies have shown that oxidative stress may contribute to APS pathophysiology. In peripheral blood mononuclear cells (PBMCs) from thrombotic Primary APS (thrPAPS) patients and age/sex-matched healthy controls (HC), as well as a control group of asymptomatic antiphospholipid antibody (aPL) positive individuals without APS (aPL+/non-APS), we examined oxidative stress, abasic (apurinic/apyrimidinic) sites, and DNA damage response (DDR)-associated parameters, including endogenous DNA damage (single- and double-strand breaks) and DNA repair mechanisms, namely nucleotide excision repair (NER) and double-strand breaks repair (DSB/R). We found that thrPAPS patients exhibited significantly higher levels of endogenous DNA damage, increased oxidative stress and abasic sites, as well as lower NER and DSB/R capacities versus HC (all P < 0.001) and versus aPL+/non-APS subjects (all P < 0.05). Our findings demonstrate that oxidative stress and decreased DNA repair mechanisms contribute to the accumulation of endogenous DNA damage in PBMCs from thrPAPS patients and, if further validated, may be exploited as therapeutic targets and potential biomarkers.

The Role of Neutrophil Extracellular Traps (NETs) in the Pathogenesis of Systemic Lupus Erythematosus and Antiphospholipid Syndrome

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease of unknown aetiology [...].

The ABCs of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is a thromboinflammatory syndrome characterized by thrombotic, microvascular, obstetric, or non-thrombotic events in the setting of persistent antiphospholipid antibodies (aPL), namely anticardiolipin antibody (aCL), anti-β2 glycoprotein-I antibody (aβ2GPI), and lupus anticoagulant (LA). The diagnosis of APS requires careful assessment of the aPL profile, the clinical phenotype, and additional risk factors. The standard management of aPL-related thrombosis is anticoagulation, which is not effective for microvascular and non-thrombotic events. In parallel to our improved understanding of aPL-related mechanisms, the role of immunosuppression has been increasingly investigated. In this review, we summarize the basic concepts and future perspectives in APS.

Type I interferon pathway assays in studies of rheumatic and musculoskeletal diseases: a systematic literature review informing EULAR points to consider

OBJECTIVES

To systematically review the literature for assay methods that aim to evaluate type I interferon (IFN-I) pathway activation and to harmonise-related terminology.

METHODS

Three databases were searched for reports of IFN-I and rheumatic musculoskeletal diseases. Information about the performance metrics of assays measuring IFN-I and measures of truth were extracted and summarised. A EULAR task force panel assessed feasibility and developed consensus terminology.

RESULTS

Of 10 037 abstracts, 276 fulfilled eligibility criteria for data extraction. Some reported more than one technique to measure IFN-I pathway activation. Hence, 276 papers generated data on 412 methods. IFN-I pathway activation was measured using: qPCR (n=121), immunoassays (n=101), microarray (n=69), reporter cell assay (n=38), DNA methylation (n=14), flow cytometry (n=14), cytopathic effect assay (n=11), RNA sequencing (n=9), plaque reduction assay (n=8), Nanostring (n=5), bisulphite sequencing (n=3). Principles of each assay are summarised for content validity. Concurrent validity (correlation with other IFN assays) was presented for n=150/412 assays. Reliability data were variable and provided for 13 assays. Gene expression and immunoassays were considered most feasible. Consensus terminology to define different aspects of IFN-I research and practice was produced.

CONCLUSIONS

Diverse methods have been reported as IFN-I assays and these differ in what elements or aspects of IFN-I pathway activation they measure and how. No 'gold standard' represents the entirety of the IFN pathway, some may not be specific for IFN-I. Data on reliability or comparing assays were limited, and feasibility is a challenge for many assays. Consensus terminology should improve consistency of reporting.

Association between type I interferon pathway activation and clinical outcomes in rheumatic and musculoskeletal diseases: a systematic literature review informing EULAR points to consider

BACKGROUND

Type I interferons (IFN-I) contribute to a broad range of rheumatic and musculoskeletal diseases (RMDs). Compelling evidence suggests that the measurement of IFN-I pathway activation may have clinical value. Although several IFN-I pathway assays have been proposed, the exact clinical applications are unclear. We summarise the evidence on the potential clinical utility of assays measuring IFN-I pathway activation.

METHODS

A systematic literature review was conducted across three databases to evaluate the use of IFN-I assays in diagnosis and monitor disease activity, prognosis, response to treatment and responsiveness to change in several RMDs.

RESULTS

Of 366 screened, 276 studies were selected that reported the use of assays reflecting IFN-I pathway activation for disease diagnosis (n=188), assessment of disease activity (n=122), prognosis (n=20), response to treatment (n=23) and assay responsiveness (n=59). Immunoassays, quantitative PCR (qPCR) and microarrays were reported most frequently, while systemic lupus erythematosus (SLE), rheumatoid arthritis, myositis, systemic sclerosis and primary Sjögren's syndrome were the most studied RMDs. The literature demonstrated significant heterogeneity in techniques, analytical conditions, risk of bias and application in diseases. Inadequate study designs and technical heterogeneity were the main limitations. IFN-I pathway activation was associated with disease activity and flare occurrence in SLE, but their incremental value was uncertain. IFN-I pathway activation may predict response to IFN-I targeting therapies and may predict response to different treatments.

CONCLUSIONS

Evidence indicates potential clinical value of assays measuring IFN-I pathway activation in several RMDs, but assay harmonisation and clinical validation are urged. This review informs the EULAR points to consider for the measurement and reporting of IFN-I pathway assays.

Whole blood transcriptome identifies interferon-regulated genes as key drivers in thrombotic primary antiphospholipid syndrome

OBJECTIVE

Pathogenesis of antiphospholipid syndrome (APS) isn't fully elucidated. We aimed to identify gene signatures characterizing thrombotic primary APS (thrPAPS) and subgroups at high risk for worse outcomes.

METHODS

We performed whole blood next-generation RNA-sequencing in 62 patients with thrPAPS and 29 age-/sex-matched healthy controls (HCs), followed by differential gene expression analysis (DGEA) and enrichment analysis. We trained models on transcriptomics data using machine learning.

RESULTS

DGEA of 12.306 genes revealed 34 deregulated genes in thrPAPS versus HCs; 33 were upregulated by at least 2-fold, and 14/33 were type I and II interferon-regulated genes (IRGs) as determined by interferome database. Machine learning applied to deregulated genes returned 79% accuracy to discriminate thrPAPS from HCs, which increased to 82% when only the most informative IRGs were analyzed. Comparison of thrPAPS subgroups versus HCs showed an increased presence of IRGs among upregulated genes in venous thrombosis (21/23, 91%), triple-antiphospholipid antibody (aPL) positive (30/50, 60%), and recurrent thrombosis (19/42, 45%) subgroups. Enrichment analysis of upregulated genes in triple-aPL positive patients revealed terms related to 'type I interferon signaling pathway' and 'innate immune response'. DGEA among thrPAPS subgroups revealed upregulated genes, including IRGs, in patients with venous versus arterial thrombosis (n = 11, 9 IRGs), triple-aPL versus non-triple aPL (n = 10, 9 IRGs), and recurrent versus non-recurrent thrombosis (n = 10, 3 IRGs).

CONCLUSION

Upregulated IRGs may better discriminate thrPAPS from HCs than all deregulated genes in peripheral blood. Taken together with DGEA data, IRGs are highly expressed in thrPAPS and high-risk subgroups of triple-aPL and recurrent thrombosis, with potential treatment implications.

Association between interferon-I producing plasmacytoid dendritic cells and thrombotic antiphospholipid syndrome

Background: Thrombotic risk in antiphospholipid syndrome (APS) is conferred by the association of antiphospholipid (aPL) antibodies (first hit) with additional pro-coagulant stimulus (second hit), such as inflammation. Among inflammatory responses, the production of large amounts of interferon (IFN)-I by plasmacytoid dendritic cells (pDCs) is at the basis of the pathophysiology of systemic autoimmune disorders, which raises the hypothesis that this mechanism could also be associated with vascular manifestations of APS. Purpose: Here, we determined the association of pDCs and IFN-I production with thrombotic APS. Research design: Patients with thrombotic primary (t-PAPS) and secondary APS (t-SAPS), asymptomatic aPL carriers and individuals without thrombosis (controls) were included. Data collection and analysis: Circulating pDCs and IFN-α intracellular expression (in the presence or not of oligodeoxynucleotides (CP) stimulus) were quantified by flow cytometry. The expression of five IFN-I inducing genes: ISG15, OASL, Ly6E, MX1, and OAS1 in mononuclear cells was determined by qPCR. Between-group differences were evaluated using chi-square or Kruskal-Wallis tests. Results: A total of 50 patients with t-PAPS, 50 patients with t-SAPS, 20 aPL carriers, and 50 individuals without thrombosis (controls) were included. Intracellular expression of IFN-α was increased after CPG stimulation in both t-SAPS (1.56%; IQR 1.07-2.02) and t-PAPS (0.96%; IQR 0.55-1.24), when compared to aPL carriers (0.71%; IQR 0.42-0.93) and controls (0.48%; IQR 0.24-0.78; p < .0001). ISG15, OASL, Ly6E, MX1, and OAS1 mRNA expressions were higher in t-SAPS (but not in t-PAPS) than in aPL carriers and controls. The expression of proteins and mRNA related to IFN-I response was similar between the triple aPL-positive profile and other aPL profiles. Conclusion: Our results indicate an association of IFN-I response and t-APS. Since IFN-I expression was not increased in aPL carriers or associated with a higher-risk aPL profile, this mechanism does not appear to be related to the presence of aPL alone. IFN-I response could possibly constitute a complementary mechanism for triggering clinical manifestations in APS.

Defibrotide Inhibits Antiphospholipid Antibody-Mediated Neutrophil Extracellular Trap Formation and Venous Thrombosis

OBJECTIVE

Defibrotide is a heterogenous mixture of polyanionic oligonucleotides currently approved for treatment of transplant-associated venoocclusive disease. While defibrotide has a known role in limiting endothelial cell activation, some studies have also demonstrated anti-leukocyte properties. In a recent study, we found that neutrophil extracellular traps (NETs) play a role in the thrombotic complications of antiphospholipid syndrome (APS). In the present study, we investigated the hypothesis that defibrotide might act to mitigate APS-relevant NET formation in vitro and in mouse models.

METHODS

We used in vitro assays and a mouse model to determine the mechanisms by which defibrotide inhibits NET formation and venous thrombosis in APS.

RESULTS

At doses ranging from 1 to 10 μg/ml, defibrotide significantly suppressed NET formation from control neutrophils stimulated with IgG isolated from patients with APS. Defibrotide increased levels of intracellular cyclic AMP in neutrophils, and its suppressive effects on NET formation were mitigated by blocking adenosine A2A receptor or by inhibiting the cyclic AMP-dependent kinase protein kinase A. Defibrotide at doses ranging from 15 to 150 mg/kg/day inhibited NET formation and venous thrombosis in a model of antiphospholipid antibody-accelerated thrombosis-an effect that was reduced in adenosine A2A receptor-knockout mice.

CONCLUSION

This study is the first to demonstrate mechanisms by which defibrotide counteracts neutrophil-mediated thrombotic inflammation inherent to APS.

Cardiovascular disease risk in antiphospholipid syndrome: Thrombo-inflammation and atherothrombosis

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by the presence of antiphospholipid antibodies (aPL) (lupus anticoagulant, anticardiolipin antibodies and anti-beta2glycoprotein I (anti-β2GPI) antibodies) and a plethora of macro- and micro-vascular manifestations, affecting predominantly young adults. Cardiovascular events are the leading causes of morbidity and mortality in APS. APL-mediated thrombo-inflammation and atherothrombosis are emerging pathogenetic mechanisms of cardiovascular disease (CVD) in APS, involving endothelial cell and monocyte activation, cytokines and adhesion molecules expression, complement and neutrophils activation, neutrophil extracellular traps formation, platelet cell activation and aggregation, and subsequent thrombin generation, in parallel with an oxidized low-density lipoprotein (oxLDL)-β2GPI complex induced macrophage differentiation to foam cells. High risk aPL profile, especially the presence of lupus anticoagulant and triple aPL positivity (all three aPL subtypes), co-existence with Systemic Lupus Erythematosus (SLE), as well as traditional risk factors such as smoking, hypertension, hyperlipemia and obesity are associated with both subclinical atherosclerosis and cardiovascular events in APS. Increased awareness of CVD risk by the physicians and patients, regular assessment and strict control of traditional risk factors, and lifestyle modifications are recommended. Use of low-dose aspirin should be considered for cardiovascular prevention in asymptomatic aPL carriers or SLE patients with high-risk aPL profile. The role of older agents such as hydroxychloroquine and statins or new potential targeted treatments against immuno- and athero-thrombosis has been demonstrated by experimental and some clinical studies and needs to be further evaluated by randomized controlled studies. This review summarizes the available evidence about the pathogenetic mechanisms and prevalence of cardiovascular events and subclinical atherosclerosis, the interrelationship between traditional and disease-related CVD risk factors, and the cardiovascular risk assessment and management in APS.

An Update on Antiphospholipid Syndrome

PURPOSE OF REVIEW

To review the recent available evidence on epidemiology, pathogenesis, clinical phenotypes, and management of antiphospholipid syndrome (APS) and summarize potential future research perspectives.

RECENT FINDINGS

Accumulating evidence has further expanded our understanding of the disease, including new data about the incidence and prevalence of APS, novel pathways supporting the role of thrombo-inflammation in APS including platelet, monocyte and endothelial cell activation, pro-inflammatory cytokine and chemokine production, complement activation, neutrophil extracellular trap release, and type I interferon gene expression that could yield to new potential treatment targets, better identification of criteria and non-criteria clinical phenotypes, antiphospholipid antibody profiles and their associations with clinical outcomes, prognostic tools, and treatment strategies based on recent evidence-based recommendations for patients with thrombotic and obstetric APS, with or without systemic lupus erythematosus. Ongoing research efforts and international collaborations enhance our knowledge of this rare and often devastating syndrome and help improve patient care and health outcomes.

Dendritic Cells and Antiphospholipid Syndrome: An Updated Systematic Review

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by autoreactive B and T cells against β2-glycoprotein I (B2GPI), with vascular thrombosis or obstetrical complications. Dendritic cells (DCs) are crucial in the generation of autoimmunity. Here, we conducted a comprehensive systematic review on the relationship between DC and APS. We performed a literature search of PubMed as of 26 March 2021. A total of 33 articles were extracted. DCs are pivotal in inducing inflammatory responses and orchestrating adaptive immunity. DCs contribute to the local inflammation regarding vascular thrombosis or obstetrical complications. Both B2GPI and antiphospholipid antibodies (aPL) can promote antigen presentation by DCs and the generation or maintenance of autoimmunity. In addition, plasmacytoid DC activation is enhanced by aPL, thereby augmenting the inflammatory response. In line with these findings, DC modulation appears promising as a future treatment for APS. In conclusion, our review indicated the crucial role of DCs in the pathogenesis of APS. Deeper understanding of the complex relationship would help in developing new treatment strategies.

Potential Implications of a Type 1 Interferon Gene Signature on COVID-19 Severity and Chronic Inflammation in Sickle Cell Disease

At the onset of the corona virus disease 19 (COVID-19) pandemic, there were concerns that patients with sickle cell disease (SCD) might be especially vulnerable to severe sequelae of SARS-CoV-2 infection. While two reports support this conclusion, multiple studies have reported unexpectedly favorable outcomes in patients with SCD. However, mechanisms explaining these disparate conclusions are lacking. Here, we review recent studies indicating that the majority of patients with SCD express elevated levels of anti-viral type 1 interferons (IFNα/β) and interferon stimulated genes, independent of COVID-19, during their baseline state of health. We also present our data from the pre-COVID-19 era, illustrating elevated expression of a well-characterized interferon stimulated gene in a cohort of patients with SCD, compared to race-matched controls. These type 1 interferons and interferon stimulated genes have the potential to contribute to the variable progression of COVID-19 and other viral infections in patients with SCD. While the majority of evidence supports a protective role, the role of IFNα/β in COVID-19 severity in the general population remains an area of current investigation. We conclude that type 1 interferon responses in patients with SCD may contribute to the variable COVID-19 responses reported in prior studies. Additional studies investigating the mechanisms underlying IFNα/β production and other clinical consequences of IFNα/β-mediated inflammation in SCD disease are warranted.

Utilizing type I interferon expression in the identification of antiphospholipid syndrome subsets

INTRODUCTION

Antiphospholipid Syndrome (APS) is a systemic autoimmune disease with a complex multifactorial pathogenesis, combining genetic background, traditional cardiovascular risk factors, disease-specific features such as the presence of antiphospholipid antibodies (aPL), and an imbalance of various immune system functions. Recent data support the role of interferons (IFNs), especially type IIFN (IFN-I), in the onset and development of APS clinical manifestations, including thrombotic events and obstetric complications.

AREAS COVERED

In this review, the authors aimed to discuss the growing body of evidence on the relevance of IFN-I pathways in APS, both from a basic mechanistic perspective, focusing on its possible use in disease/patients stratification. The IFN-I signature has shown promising, although preliminary, results in segregating aPL-positive subjects by aPL profile, association with other autoimmune conditions, such as lupus, age at onset, and current treatment, among others.

EXPERT OPINION

To date, the scarce available data as well as methodological and technical heterogeneity among studies limit the comparability of the results, thus requiring further validation to translate these findings to routine clinical practice. Therefore, further research is required in pursuit of more nuanced patient profiling and the development of new immunomodulatory therapeutic strategies for APS beyond anti-coagulant and antiplatelet agents.

Linking clotting and autoimmunity

A receptor for phospholipid antibodies drives clotting and inflammation

Antiphospholipid syndrome: a clinical perspective

Antiphospholipid syndrome (APS) is a thromboinflammatory disease with a variety of clinical phenotypes. Primary thrombosis prophylaxis should take an individualized risk stratification approach. Moderate-intensity vitamin K antagonist such as warfarin remains the primary strategy for secondary thrombosis prophylaxis among APS patients, especially for patients with predominantly venous disease. For now, direct oral anti-coagulants should be avoided in most APS patients, especially those with history of arterial manifestations. Obstetric APS management should be tailored based on an individual patient's antiphospholipid antibody profile, and obstetric and thrombotic history. Pharmacological agents beyond anticoagulants may be considered for the management of microthrombotic and nonthrombotic manifestations of APS, although more data are needed. A relatively recent discovery in the area of APS pathogenesis is the implication of neutrophil extracellular traps in thrombin generation and initiation of inflammatory cascades. APS is a complex thromboinflammatory disease with a broad clinical spectrum. Personalized therapy according to an individual's unique thrombosis and obstetric risk should be advocated.

Comparable or higher prevalence of comorbidities in antiphospholipid syndrome vs rheumatoid arthritis: a multicenter, case-control study

OBJECTIVES

Evidence on comorbidity prevalence in antiphospholipid syndrome (APS) and its difference from high comorbidity burden rheumatic diseases is limited. Herein, we compare multiple comorbidities between APS and RA.

METHODS

A total of 326 patients from the Greek APS registry [237 women, mean age 48.7 (13.4) years, 161 primary APS (PAPS), 165 SLE-APS] were age/sex matched (1:2 ratio) with 652 patients from a Greek multicentre RA cohort of 3115 patients. Prevalence of cardiovascular (CV) risk factors, stroke, coronary artery disease (CAD), osteoporosis, diabetes mellitus (DM), chronic obstructive pulmonary disease (COPD), depression and neoplasms were compared between APS and RA patients using multivariate regression analysis.

RESULTS

Ηyperlipidemia and obesity (ΒΜΙ ≥ 30 kg/m2) were comparable while hypertension, smoking, stroke and CAD were more prevalent in APS compared with RA patients. Osteoporosis and depression were more frequent in APS, while DM, COPD and neoplasms did not differ between the two groups. Comparison of APS subgroups to 1:2 matched RA patients revealed that smoking and stroke were more prevalent in both PAPS and SLE-APS vs RA. Hypertension, CAD and osteoporosis were more frequent only in SLE-APS vs RA, whereas DM was less prevalent in PAPS vs RA. Hyperlipidaemia was independently associated with CV events (combined stroke and CAD) in PAPS and SLE-APS, while CS duration was associated with osteoporosis in SLE-APS.

CONCLUSION

Comorbidity burden in APS (PAPS and SLE-APS) is comparable or higher than that in RA, entailing a high level of diligence for CV risk prevention, awareness for depression and CS exposure minimization.

16th International Congress on Antiphospholipid Antibodies Task Force Report on Antiphospholipid Syndrome Treatment Trends

Antiphospholipid syndrome (APS), an acquired autoimmune thrombophilia, is characterised by thrombosis and/or pregnancy morbidity in association with persistent antiphospholipid antibodies. The 16th International Congress on Antiphospholipid Antibodies Task Force on APS Treatment Trends reviewed the current status with regard to existing and novel treatment trends for APS, which is the focus of this Task Force report. The report addresses current treatments and developments since the last report, on the use of direct oral anticoagulants in patients with APS, antiplatelet agents, adjunctive therapies (hydroxychloroquine, statins and vitamin D), targeted treatment including rituximab, belimumab, and anti-TNF agents, complement inhibition and drugs based on peptides of beta-2-glycoprotein I. In addition, the report summarises potential new players, including coenzyme Q10, adenosine receptor agonists and adenosine potentiation. In each case, the report provides recommendations for clinicians, based on the current state of the art, and suggests a clinical research agenda. The initiation and development of appropriate clinical studies requires a focus on devising suitable outcome measures, including a disease activity index, an optimal damage index, and a specific quality of life index.

NETs in APS: Current Knowledge and Future Perspectives

PURPOSE OF REVIEW

Antiphospholipid syndrome (APS) is a thrombo-inflammatory disease that is primarily treated with anticoagulation. Better understanding the inflammatory aspects of APS could lead to safer, more effective, and more personalized therapeutic options. To this end, we sought to understand recent literature related to the role of neutrophils and, in particular, neutrophil extracellular traps (NETs) in APS.

RECENT FINDINGS

Expression of genes associated with type I interferons, endothelial adhesion, and pregnancy regulation are increased in APS neutrophils. APS neutrophils have a reduced threshold for NET release, which likely potentiates thrombotic events and perhaps especially large-vein thrombosis. Neutrophil-derived reactive oxygen species also appear to play a role in APS pathogenesis. There are new approaches for preventing and disrupting NETs that could potentially be leveraged to reduce the risk of APS-associated thrombosis. Neutrophils and NETs contribute to APS pathophysiology. More precisely understanding their roles at a mechanistic level should help identify new therapeutic targets for inhibiting NET formation, enhancing NET dissolution, and altering neutrophil adhesion. Such approaches may ultimately lead to better clinical management of APS patients and thereby reduce the chronic burden of this disease.

Management of Non-criteria Manifestations in Antiphospholipid Syndrome

PURPOSE OF THE REVIEW

To review the available evidence on the management of a variety of non-criteria manifestations in antiphospholipid syndrome (APS), including valvular disease, alveolar hemorrhage, thrombocytopenia, hemolytic anemia, APS nephropathy, skin ulcers, livedo reticularis, cognitive dysfunction, and epilepsy.

RECENT FINDINGS

Current treatment relies on low-level evidence and mainly on expert consensus due to the rarity and the heterogeneity of non-criteria APS manifestations and the diversity in management approaches. Conventional anticoagulation and/or antiplatelet APS treatment do not adequately control most of non-criteria manifestations. Increasing knowledge about the contribution of inflammatory in addition to, or independently of, thrombotic mechanisms in non-criteria APS manifestations provides insight into the potential effect of novel therapies targeting B-cells, mammalian target of rapamycin, neutrophil, and complement or interferon pathways. Existing evidence is limited by lack of high-quality studies. Better understanding of the pathophysiology and clinical phenotypes of APS and well-designed prospective studies of homogenous populations are needed to provide evidence-based recommendations for the management of non-criteria APS manifestations.

Type-I interferons in atherosclerosis

Chen et al. review the effects of type-I IFNs and the potential of anti–type-I IFN therapies in atherosclerosis.

The contribution of dyslipidemia and inflammation in atherosclerosis is well established. Along with effective lipid-lowering treatments, the recent success of clinical trials with anti-inflammatory therapies and the accelerated atherosclerosis in many autoimmune diseases suggest that targeting inflammation may open new avenues for the prevention and the treatment for cardiovascular diseases (CVDs). In the past decades, studies have widened the role of type-I interferons (IFNs) in disease, from antivirus defense to autoimmune responses and immuno-metabolic syndromes. While elevated type-I IFN level in serum is associated with CVD incidence in patients with interferonopathies, experimental data have attested that type-I IFNs affect plaque-residing macrophages, potentiate foam cell and extracellular trap formation, induce endothelial dysfunction, alter the phenotypes of dendritic cells and T and B lymphocytes, and lead to exacerbated atherosclerosis outcomes. In this review, we discuss the production and the effects of type-I IFNs in different atherosclerosis-associated cell types from molecular biology studies, animal models, and clinical observations, and the potential of new therapies against type-I IFN signaling for atherosclerosis.

Pediatric antiphospholipid syndrome

Despite its potential to cause significant morbidity in children, pediatric antiphospholipid syndrome (APS) is an understudied condition. In this review, we will cover what is known about pediatric APS epidemiology and how the clinician might approach the diagnosis of pediatric APS. We will highlight similarities and differences with the adult disease, both for primary APS and in the context of lupus. Clinical manifestations beyond thrombosis, especially neurologic and hematologic in nature, will be discussed. We will also consider what unique implications antiphospholipid antibody-positivity may have for children with lupus and for neonates born to mothers with APS. The approach to treatment will be covered, including the unique impact of APS medications on children as compared with adults. Finally, the importance of future mechanistic research is emphasized as physicians endeavor to provide the personalized care that children with APS clearly deserve.

Independent association of low IFNλ1 gene expression and type I IFN score/IFNλ1 ratio with obstetric manifestations and triple antiphospholipid antibody positivity in primary antiphospholipid syndrome

Recent data suggest an important role of type I interferons (IFN) in antiphospholipid syndrome (APS). Here we aimed to evaluate the interplay of type I and type III (or IFNλs) IFNs in APS and potential clinical and serological associations. Our findings suggest that patients with primary APS (PAPS) and systemic lupus erythematosus (SLE)/APS displayed increased type I IFN scores but decreased IFNλ1 gene expression levels compared to healthy individuals, as assessed with real-time qPCR analysis in isolated peripheral blood mononuclear cells (PBMCs). Type I IFN score/IFNλ1 ratio was remarkably higher in patients with PAPS and SLE/APS as well as in SLE patients with or without antiphospholipid antibodies (aPL) vs controls. In conclusion, our results reveal an association between low IFNλ1 expression and obstetric APS. Moreover, the type I IFN score/IFNλ1 ratio seems to be a potential marker of high risk APS given its associations with triple aPL positivity.

Neutrophils-Important Communicators in Systemic Lupus Erythematosus and Antiphospholipid Syndrome

Systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) are two autoimmune diseases that can occur together or separately. Insights into the pathogenesis have revealed similarities, such as development of autoantibodies targeting subcellular antigens as well as a shared increased risk of cardiovascular morbidity, potentially due to mutual pathologic mechanisms. In this review, we will address the evidence implicating neutrophils in the pathogenesis of these conditions, highlighting their shared features. The neutrophil is the most abundant leukocyte, recognized for its role in infectious and inflammatory diseases, but dysregulation of neutrophil effector functions, including phagocytosis, oxidative burst and formation of neutrophil extracellular traps (NETs) may also contribute to an autoimmune process. The phenotype of neutrophils in SLE and APS differs from neutrophils of healthy individuals, where neutrophils in SLE and APS are activated and prone to aggregate. A specific subset of low-density neutrophils with different function compared to normal-density neutrophils can also be found within the peripheral blood mononuclear cell (PBMC) fraction after density gradient centrifugation of whole blood. Neutrophil phagocytosis is required for regular clearance of cell remnants and nuclear material. Reactive oxygen species (ROS) released by neutrophils during oxidative burst are important for immune suppression and impairment of ROS production is seen in SLE. NETs mediate pathology in both SLE and APS via several mechanisms, including exposure of autoantigens, priming of T-cells and activation of autoreactive B-cells. NETs are also involved in cardiovascular events by forming a pro-thrombotic scaffolding surface. Lastly, neutrophils communicate with other cells by producing cytokines, such as Interferon (IFN) -α, and via direct cell-cell contact. Physiological neutrophil effector functions are necessary to prevent autoimmunity, but in SLE and APS these are altered.

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.

An Easy and Reliable Strategy for Making Type I Interferon Signature Analysis Comparable among Research Centers

Interferon-stimulated genes (ISGs) are a set of genes whose transcription is induced by interferon (IFN). The measure of the expression of ISGs enables calculating an IFN score, which gives an indirect estimate of the exposition of cells to IFN-mediated inflammation. The measure of the IFN score is proposed for the screening of monogenic interferonopathies, like the Aicardi-Goutières syndrome, or to stratify subjects with systemic lupus erythematosus to receive IFN-targeted treatments. Apart from these scenarios, there is no agreement on the diagnostic value of the score in distinguishing IFN-related disorders from diseases dominated by other types of cytokines. Since the IFN score is currently measured in several research hospitals, merging experiences could help define the potential of scoring IFN inflammation in clinical practice. However, the IFN score calculated at different laboratories may be hardly comparable due to the distinct sets of IFN-stimulated genes assessed and to different controls used for data normalization. We developed a reliable approach to minimize the inter-laboratory variability, thereby providing shared strategies for the IFN signature analysis and allowing different centers to compare data and merge their experiences.

Type I interferon gene expression in antiphospholipid syndrome: Pathogenetic, clinical and therapeutic implications

Type I Interferon gene expression has been shown to play an important role in the pathogenesis of several systemic autoimmune disorders, paving the way for its potential use as a surrogate marker or a therapeutic tool. While the concept of type I interferon signature and its correlation with clinical phenotypes and disease activity, along with anti-interferon targeted therapy have been vastly investigated in patients with systemic lupus erythematosus, there is a paucity of data concerning antiphospholipid syndrome patients. In this review, we summarize the current knowledge on the pathogenetic and clinical implications of type I interferon expression in antiphospholipid syndrome and discuss the therapeutic possibility of targeting molecules along the interferon signaling pathway. A number of recent studies have shown a type I interferon gene expression induction in patients with primary antiphospholipid syndrome via the plasmacytoid dendritic cell pathway, toll like receptors (TLRs) such as TLR7 and TLR9, anti-beta2glycoprotein I antibody-mediated neutrophil activation and neutrophil extracellular traps (NETs) release in a TLR4-dependent fashion, and a subsequent B cell and plasmablast activation. An association between type I interferon expression and several demographic, clinical and laboratory characteristics including age, gender, pregnancy complications such as eclampsia, anti-beta2glycoprotein I antibodies, and a negative correlation with hydroxychloroquine and/or statin use, has been shown. Correlation of high interferon scores to worse outcomes in prospective studies could direct the initiation for a prompt treatment in high-risk populations. Potential therapeutic approaches targeting type I interferon production and signaling pathway components might include anti-interferon or interferon receptor monoclonal antibodies, or an interferon based therapeutic vaccine as was indicated from previous systemic lupus erythematosus studies, TLR inhibitors including hydroxychloroquine and anti-TLR antibodies, plasmacytoid dendritic cell inhibition, adenosine-receptor agonists, and plasmablast targeting treatments. Well-designed studies are needed to further assess the immunomodulatory potential of the above targets for therapeutic intervention in patients with primary antiphospholipid syndrome.

Type I Interferon Signature in Primary Antiphospholipid Syndrome: Clinical and Laboratory Associations

Background: Increased expression of type I interferon (IFN)-regulated genes has been described in blood and tissue cells from patients with systemic lupus erythematosus (SLE) and other rheumatic disorders. Only isolated studies have examined the type I IFN gene expression in antiphosholipid syndrome (APS), while efforts to evaluate associations with APS-related factors are scarce.

Objective: Our aim was to investigate the type I IFN signature in patients with primary APS (PAPS), SLE/APS, and SLE in comparison with healthy controls, and to evaluate associations with disease-related characteristics.

Methods: We measured the type I IFN score, derived from relative expressions of three IFN-inducible genes (MX-1, IFIT-1, and IFI-44) in peripheral blood mononuclear cells from 55 patients with PAPS, 34 with SLE/APS, 48 with SLE, and 28 controls. In patients with PAPS, we performed multivariate regression to examine associations of type I IFN score with their clinical, laboratory and treatment characteristics.

Results: Type I IFN score was increased in all patient groups vs. controls (p = 0.028, p = 0.027, p = 0.028 for PAPS, SLE/APS, and SLE, respectively). IFI-44 had the most pronounced expression. In patients with PAPS, multivariate linear regression revealed positive associations of type I IFN score with female gender (b-coefficient = 0.49; 95% CI 0.04, 0.94; p = 0.034) and IgG or IgM anti-β2GPI antibodies (b-coefficient = 0.53; 95% CI 0.10, 0.96; p = 0.017), and negative associations with age (b-coefficient = −0.02/year; 95% CI −0.04, −0.01; p = 0.027) and hydroxychloroquine use (b-coefficient = −0.51; 95% CI-0.96, −0.06; p = 0.027).

Conclusion: Type I IFN score is increased in PAPS and correlated positively with anti-β2GPI antibodies and negatively with hydroxychloroquine use.

Two subgroups in systemic lupus erythematosus with features of antiphospholipid or Sjögren's syndrome differ in molecular signatures and treatment perspectives

Background

Previous studies and own clinical observations of patients with systemic lupus erythematosus (SLE) suggest that SLE harbors distinct immunophenotypes. This heterogeneity might result in differences in response to treatment in different subgroups and obstruct clinical trials. Our aim was to understand how SLE subgroups may differ regarding underlying pathophysiology and characteristic biomarkers.

Methods

In a cross-sectional study, including 378 well-characterized SLE patients and 316 individually matched population controls, we defined subgroups based on the patients’ autoantibody profile at inclusion. We selected a core of an antiphospholipid syndrome-like SLE (aPL+ group; positive in the lupus anticoagulant (LA) test and negative for all three of SSA (Ro52 and Ro60) and SSB antibodies) and a Sjögren’s syndrome-like SLE (SSA/SSB+ group; positive for all three of SSA (Ro52 and Ro60) and SSB antibodies but negative in the LA test). We applied affinity-based proteomics, targeting 281 proteins, together with well-established clinical biomarkers and complementary immunoassays to explore the difference between the two predefined SLE subgroups.

Results

The aPL+ group comprised 66 and the SSA/SSB+ group 63 patients. The protein with the highest prediction power (receiver operating characteristic (ROC) area under the curve = 0.89) for separating the aPL+ and SSA/SSB+ SLE subgroups was integrin beta-1 (ITGB1), with higher levels present in the SSA/SSB+ subgroup. Proteins with the lowest p values comparing the two SLE subgroups were ITGB1, SLC13A3, and CERS5. These three proteins, rheumatoid factor, and immunoglobulin G (IgG) were all increased in the SSA/SSB+ subgroup. This subgroup was also characterized by a possible activation of the interferon system as measured by high KRT7, TYK2, and ETV7 in plasma. In the aPL+ subgroup, complement activation was more pronounced together with several biomarkers associated with systemic inflammation (fibrinogen, α-1 antitrypsin, neutrophils, and triglycerides).

Conclusions

Our observations indicate underlying pathogenic differences between the SSA/SSB+ and the aPL+ SLE subgroups, suggesting that the SSA/SSB+ subgroup may benefit from IFN-blocking therapies while the aPL+ subgroup is more likely to have an effect from drugs targeting the complement system. Stratifying SLE patients based on an autoantibody profile could be a way forward to understand underlying pathophysiology and to improve selection of patients for clinical trials of targeted treatments.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1836-8) contains supplementary material, which is available to authorized users.

Endothelial cell injury is involved in atherosclerosis and lupus symptoms in gld.apoE- / - mice

AIM

Cardiovascular complications related to atherosclerosis are major causes of morbidity and mortality in patients with systemic lupus erythematosus (SLE). However, the underlying mechanisms are not fully understood. Endothelial dysfunction has been identified as having involvement in pathogenesis of cardiovascular diseases and SLE. This study aims to evaluate endothelial cell injury in mice with the combination of lupus and atherosclerosis.

METHODS

The mouse model of accelerated atherosclerosis in lupus (gld.apoE^{- / -} mouse) was generated from apolipoprotein E-deficient (apoE^{- / -} ) and Fasl^gld C57BL/6 mice. The lupus-like autoimmunity and atherosclerotic lesions were evaluated. The endothelial cell injury was determined.

RESULTS

The results showed that the double-mutant gld.apoE^{- / -} mice were generated. Spleens from 5-month-old gld.apoE^{- / -} mice were significantly enlarged compared with wild-type mice (WT mice). The gld.apoE^{- / -} mice produced high levels of total immunoglobulin G (IgG) and IgM and showed marked increase of IgG and C3 deposits in the glomeruli. The gld.apoE^{- / -} mice displayed a pattern of glomerulonephritis typically found in SLE. The gld.apoE^{- / -} mice have high levels of serum creatinine. The total cholesterol, low-density lipoprotein cholesterol and triglycerides were significantly increased, while high-density lipoprotein cholesterol decreased in the double-mutant mice. The circulating endothelial progenitor cells were significantly decreased. The serum levels of thrombomodulin and vascular cell adhesion molecule-1 were significantly elevated in gld.apoE^{- / -} mice. The gld.apoE^{- / -} mice simultaneously exhibited SLE and atherosclerosis characteristics.

CONCLUSION

Our findings indicated that endothelial cell injury might be a biomarker for evaluating risks of cardiovascular disease in SLE and targeting endothelial cell dysfunction might prevent and treat atherosclerosis in SLE.

Pathogenesis of antiphospholipid syndrome: recent insights and emerging concepts

Introduction: Even though our understanding of the antiphospholipid syndrome (APS) has improved tremendously over the last decades, we are still not in a position to replace symptomatic anticoagulation by pathogenesis based causal treatments. Areas covered: Recent years have provided further insights into pathogenetically relevant mechanisms. These include a differentiation of pathogenic subtypes of antiphospholipid antibodies (aPL), novel mechanisms modulating disease activity, for example, extracellular vesicles and microRNA, and novel players in pathogenesis, for example, neutrophils and neutrophil extracellular traps (NETs). Expert commentary: It is evident that aPL induce a proinflammatory and procoagulant state and recent data suggest that different aPL species activate different signaling pathways which sometimes converge into a common cellular response. This implies that presence of more than one aPL species may disproportionally increase the risk for the major manifestations of APS, that is, thrombosis and fetal loss. Further delineation of the pathogenic mechanisms will hopefully provide clues to causal rather than symptomatic treatments of APS.

Galectin-9 is an easy to measure biomarker for the interferon signature in systemic lupus erythematosus and antiphospholipid syndrome

Objective

The interferon (IFN) signature is related to disease activity and vascular disease in systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) and represents a promising therapeutic target. Quantification of the IFN signature is currently performed by gene expression analysis, limiting its current applicability in clinical practice. Therefore, the objective of this study was to establish an easy to measure biomarker for the IFN signature.

Methods

Serum levels of galectin-9, CXCL-10 (IP-10) and tumour necrosis factor receptor type II (TNF-RII) were measured in patients with SLE, SLE+APS and primary APS (PAPS) and healthy controls (n=148) after an initial screening of serum analytes in a smaller cohort (n=43). Analytes were correlated to measures of disease activity and the IFN signature. The performance of galectin-9, CXCL-10 and TNF-RII as biomarkers to detect the IFN signature was assessed by receiver operating characteristic curves.

Results

Galectin-9, CXCL-10 and TNF-RII were elevated in patients with SLE, SLE+APS and PAPS (p<0.05) and correlated with disease activity and tissue factor expression. Galectin-9 correlated stronger than CXCL-10 or TNF-RII with the IFN score (r=0.70, p<0.001) and was superior to CXCL-10 or TNF-RII in detecting the IFN signature (area under the curve (AUC) 0.86). Importantly, in patients with SLE(±APS), galectin-9 was also superior to anti-dsDNA antibody (AUC 0.70), or complement C3 (AUC 0.70) and C4 (AUC 0.78) levels in detecting the IFN signature.

Conclusion

Galectin-9 is a novel, easy to measure hence clinically applicable biomarker to detect the IFN signature in patients with systemic autoimmune diseases such as SLE and APS.

Gene expression profiling identifies distinct molecular signatures in thrombotic and obstetric antiphospholipid syndrome

Antiphospholipid antibodies (aPL) cause vascular thrombosis (VT) and/or pregnancy morbidity (PM). Differential mechanisms however, underlying the pathogenesis of these different manifestations of antiphospholipid syndrome (APS) are not fully understood. Therefore, we compared the effects of aPL from patients with thrombotic or obstetric APS on monocytes to identify different molecular pathways involved in the pathogenesis of APS subtypes. VT or PM IgG induced similar numbers of differentially expressed (DE) genes in monocytes. However, gene ontology (GO) analysis of DE genes revealed disease-specific genome signatures. Compared to PM, VT-IgG showed specific up regulation of genes associated with cell response to stress, regulation of MAPK signalling pathway and cell communication. In contrast, PM-IgG regulated genes involved in cell adhesion, extracellular matrix and embryonic and skeletal development. A novel gene expression analysis based on differential variability (DV) was also applied. This analysis identified similar GO categories compared to DE analysis but also uncovered novel pathways modulated solely by PM or VT-IgG. Gene expression analysis distinguished a differential effect of VT or PM-IgG upon monocytes supporting the hypothesis that they trigger distinctive physiological mechanisms. This finding contributes to our understanding of the pathology of APS and may lead to the development of different targeted therapies for VT or PM APS.

Non-medical Switching from Originator Tumor Necrosis Factor Inhibitors to Their Biosimilars: Systematic Review of Randomized Controlled Trials and Real-World Studies

Tumor necrosis factor (TNF) inhibitors are widely used biologics for the treatment of several chronic inflammatory diseases. The launch of anti-TNF biosimilars has introduced the possibility of non-medical switching between originator biologics and their biosimilars. However, the potential clinical and patient-reported consequences of non-medical switching remain largely unknown, as much of the evidence comes from poorly or uncontrolled real-world evidence (RWE) studies that often have an element of bias and nonstandardized outcome measures. To appropriately evaluate the safety, efficacy, and immunogenicity of non-medical switching from an originator to its biosimilar, we propose that seven key study design elements should be considered when assessing the existing evidence: studies should be (1) randomized and double-blind, (2) adequately controlled, and (3) adequately powered; include (4) multiple switching, (5) an assessment of immunogenicity, and (6) adequate follow-up duration; and (7) report individual patient-level outcomes. This systematic review assessed the robustness and consistency of the current non-medical switching evidence, with a focus on TNF inhibitors. A comprehensive literature search (January 2012-February 2018) identified 98 publications corresponding to 91 studies (17 randomized controlled trials and 74 RWE studies) describing non-medical switching from a TNF inhibitor originator to its biosimilar. When assessing the totality of this evidence, none of the non-medical switching studies conducted to date were found to use all seven of the key design elements, and the absence of these elements dilutes the robustness of the data. Furthermore, discontinuation rates varied widely among studies (0-87%), suggesting heterogeneity and inconclusiveness of the current efficacy, safety, and immunogenicity evidence, particularly at an individual patient level. Therefore, patients should not be indiscriminately switched from an originator TNF inhibitor to its biosimilar for non-medical reasons. Switching decisions should remain between the treating physicians and their patients and be made on a case-by-case basis, relying upon robust scientific evidence.

FUNDING

AbbVie.Plain Language Summary: Plain language summary available for this article.

Ectonucleotidase-Mediated Suppression of Lupus Autoimmunity and Vascular Dysfunction

Objectives

CD39 and CD73 are surface enzymes that jut into the extracellular space where they mediate the step-wise phosphohydrolysis of the autocrine and paracrine danger signals ATP and ADP into anti-inflammatory adenosine. Given the role of vascular and immune cells' "purinergic halo" in maintaining homeostasis, we hypothesized that the ectonucleotidases CD39 and CD73 might play a protective role in lupus.

Methods

Lupus was modeled by intraperitoneal administration of pristane to three groups of mice: wild-type (WT), CD39^-/-, and CD73^-/-. After 36 weeks, autoantibodies, endothelial function, kidney disease, splenocyte activation/polarization, and neutrophil activation were characterized.

Results

As compared with WT mice, CD39^-/- mice developed exaggerated splenomegaly in response to pristane, while both groups of ectonucleotidase-deficient mice demonstrated heightened anti-ribonucleoprotein production. The administration of pristane to WT mice triggered only subtle dysfunction of the arterial endothelium; however, both CD39^-/- and CD73^-/- mice demonstrated striking endothelial dysfunction following induction of lupus, which could be reversed by superoxide dismutase. Activated B cells and plasma cells were expanded in CD73^-/- mice, while deficiency of either ectonucleotidase led to expansion of T_H17 cells. CD39^-/- and CD73^-/- mice demonstrated exaggerated neutrophil extracellular trap release, while CD73^-/- mice additionally had higher levels of plasma cell-free DNA.

Conclusion

These data are the first to link ectonucleotidases with lupus autoimmunity and vascular disease. New therapeutic strategies may harness purinergic nucleotide dissipation or signaling to limit the damage inflicted upon organs and blood vessels by lupus.

Antiphospholipid Syndrome Nephropathy: From Pathogenesis to Treatment

Kidney damage is a well-recognized complication of the antiphospholipid syndrome (APS), either primary or systemic lupus erythematosus (SLE)-associated APS. Kidney involvement in APS involves a variety of manifestations, such as renal artery thrombosis or stenosis, renal vein thrombosis, allograft loss due to thrombosis after kidney transplantation, and injury to the renal microvasculature, also known as APS nephropathy. Biopsy in patients with APS nephropathy includes acute thrombotic microangiopathy lesions and chronic intrarenal vascular lesions such as interlobular fibrous intimal hyperplasia, arterial and arteriolar recanalizing thrombosis, fibrous arterial occlusion, and focal cortical atrophy. The most frequent clinical features are hypertension, microscopic hematuria, proteinuria (ranging from mild to nephritic levels), and renal insufficiency. It is uncertain whether antiphospholipid antibodies or other factors are implicated in the development of APS nephropathy, and whether it is driven mainly by thrombotic or by inflammatory processes. Experimental models and clinical studies of thrombotic microangiopathy lesions implicate activation of the complement cascade, tissue factor, and the mTORC pathway. Currently, the management of APS nephropathy relies on expert opinion, and consensus is lacking. There is limited evidence about the effect of anticoagulants, and their use remains controversial. Treatment approaches in patients with APS nephropathy lesions may include the use of heparin based on its role on complement activation pathway inhibition or the use of intravenous immunoglobulin and/or plasma exchange. Targeted therapies may also be considered based on potential APS nephropathy pathogenetic mechanisms such as B-cell directed therapies, complement inhibition, tissue factor inhibition, mTOR pathway inhibition, or anti-interferon antibodies, but prospective multicenter studies are needed to address their role.

Antiphospholipid syndrome: an update for clinicians and scientists

PURPOSE OF REVIEW

Antiphospholipid syndrome (APS) is a leading acquired cause of thrombosis and pregnancy loss. Upon diagnosis (which is unlikely to be made until at least one morbid event has occurred), anticoagulant medications are typically prescribed in an attempt to prevent future events. This approach is not uniformly effective and does not prevent associated autoimmune and inflammatory complications. The goal of this review is to update clinicians and scientists on mechanistic and clinically relevant studies from the past 18 months, which have especially focused on inflammatory aspects of APS pathophysiology.

RECENT FINDINGS

How antiphospholipid antibodies leverage receptors and signaling pathways to activate cells is being increasingly defined. Although established mediators of disease pathogenesis (like endothelial cells and the complement system) continue to receive intensive study, emerging concepts (such as the role of neutrophils) are also receiving increasing attention. In-vivo animal studies and small clinical trials are demonstrating how repurposed medications (hydroxychloroquine, statins, and rivaroxaban) may have clinical benefit in APS, with these concepts importantly supported by mechanistic data.

SUMMARY

As anticoagulant medications are not uniformly effective and do not comprehensively target the underlying pathophysiology of APS, there is a continued need to reveal the inflammatory aspects of APS, which may be modulated by novel and repurposed therapies.

Endothelial cell functions impaired by interferon in vitro: Insights into the molecular mechanism of thrombotic microangiopathy associated with interferon therapy

INTRODUCTION

Interferon (IFN)-α and IFN-β approved for treatment of chronic hepatitis C viral infection and multiple sclerosis respectively have been linked to thrombotic microangiopathy (TMA) affecting renal function. Since the molecular mechanisms underlying this severe complication remain largely unclear, we aimed to investigate whether IFN affects directly in vitro endothelial cell functions associated with angiogenesis and blood haemostasis, as well as endothelial cell-derived vasodilators of nitric oxide (NO) and prostacyclin.

METHODS

Proliferation and survival of human umbilical vein endothelial cells (HUVECs) were measured by BrdU incorporation and alamarBlue assays. Angiogenesis was evaluated in co-cultures of HUVECs and human dermal fibroblasts. Fibrinolysis molecules were measured with ELISA. NO and prostacyclin were measured using a fluorescent NO-specific probe and a competitive enzyme immunoassay, respectively.

RESULTS

HUVEC proliferation was dose-dependently inhibited by IFN-β1a and IFN-β1b, but not by IFN-α2a and IFN-α2b. Consistently, IFN-β1a and IFN-β1b also reduced survival of HUVECs, but this again was not observed with IFN-α. However, both IFN subtypes inhibited VEGF-induced development of capillary-like structures, but the effect of IFN-α was less potent than IFN-β. In addition, both IFN subtypes upregulated interferon inducible protein 10 production from treated co-cultures while suppressing angiogenesis. Furthermore, intracellular NO generation was reduced by IFN-α2a and IFN-β1a, whereas prostacyclin release from HUVECs was not affected by IFN. Importantly, both IFN-β1a- and IFN-β1b-treated HUVECs showed a marked reduction in urokinase-type plasminogen activator release and a much greater secretion of plasminogen activator inhibitor-1 than tissue-type plasminogen activator compared with untreated cells, suggesting decreased fibrinolytic activity. IFN-α, however was less effective in modulating the fibrinolysis system.

CONCLUSIONS

We demonstrate the detrimental effects of IFN on endothelial cell functions mediated with angiogenesis and fibrinolysis, which could potentially cause the loss of physiological endothelium thromboresistance and facilitate the development of vascular complications in a clinical setting. Mechanistically, our findings have implications for understanding how IFN therapy can foster the development of TMA.