The type I interferon system in the etiopathogenesis of autoimmune diseases

Transcriptomic Profiling of Peripheral B Cells in Antibody Positive Sjogren's Patients Reveals Interferon Signature

BACKGROUND

Sjögren's disease (SjD) is a common systemic autoimmune disease that affects mainly women. Key pathologic features include the infiltration of exocrine glands by lymphocytes and the activation of B lymphocytes with the production of autoantibodies. We aimed to analyze the transcriptome of circulating B cells from patients with SJD and healthy controls to decipher the B-cell-specific contribution to SJD.

METHODS

RNA from peripheral blood B cells of five untreated female patients with SjD and positive ANA, positive anti-SSA (both Ro-52 and Ro-60), positive anti-SSB and positive rheumatoid-factor, and five healthy controls was subjected to whole-transcriptome sequencing. A false discovery rate of < 0.1 was applied to define differentially expressed genes (DEG).

RESULTS

RNA-sequencing identified 56 up and 23 down DEG. Hierarchal clustering showed a clear separation between the two groups. Ingenuity pathway analysis revealed that these genes may play a role in interferon signaling, chronic mycobacterial infection, and transformation to myeloproliferative disorders.

CONCLUSIONS

We found upregulated expression of type-I and type-II interferon (IFN)-induced genes, as well as genes that may contribute to other concomitant conditions, including infections and a higher risk of myeloproliferative disorders. This adds insight into the autoimmune process and suggests potential targets for future functional and prognostic studies.

Screening of Genes Associated with Immune Infiltration of Discoid Lupus Erythematosus Based on Weighted Gene Co-expression Network Analysis

Discoid lupus erythematosus (DLE) is a disorder of the immune system commonly seen in women of childbearing age. The pathophysiology and aetiology are still poorly understood, and no cure is presently available. Therefore, there is an urgent need to explore the underlying molecular mechanisms, as well as search for new therapeutic targets. Gene expression data from skin biopsies samples of DLE patients and healthy controls were downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) between DLE and healthy control samples were identified by differential expression analysis. Samples were analysed using CIBERSORT to examine the proportion of immune infiltration. Weighted gene co-expression network analysis was used to screen for the module most relevant to immune infiltration. Candidate genes were uploaded to the TRRUST database to obtain the potential transcription factors regulating these genes. Protein-protein interaction (PPI) analysis was performed to obtain the hub genes most associated with immune infiltration among the candidate genes. A total of 273 DEGs were identified between the DLE and healthy control samples. The results of immunoinfiltration analysis showed that the abundances of resting memory CD4 T cells, activated memory CD4 T cells and M1 macrophages were significantly higher, while those of resting infiltration of plasma cells, regulatory T cells and dendritic cells were lower in DLE samples than in healthy control samples. Correlation analysis showed that ISG15, TRIM22, XAF1, IFIT2, OAS2, OAS3, OAS1, IFI44, IFI6, BST2, IFIT1 and MX2 were negatively correlated with the abundances of plasma cells, T-cell regulatory cells and resting dendritic cells and positively correlated with activated memory CD4 T cells and M1 macrophages. Our study shows that these hub genes may regulate DLE via immune-related pathways mediated by the infiltration of these immune cells.

A comprehensive exploration of the heterogeneity of immune cells in Han and Zang systemic lupus erythematosus patients via single-cell RNA sequencing

Systemic Lupus Erythematosus (SLE) is an autoimmune sickness with unclear pathogenesis. The goal of this research was to reveal the heterogeneity of immune cells in SLE patients of Han and Zang nationality by single-cell RNA sequencing (scRNA-seq) and bioinformatics profiling.

METHODS

A total of 94,102 peripheral blood mononuclear cells (PBMCs) from six volunteers with SLE (3 Zang, 3 Han) and six healthy controls were first conducted through scRNA-seq analysis. The immune cell subsets in the pathogenesis of SLE were analyzed as well. Real-time quantitative PCR (RT-qPCR) was applied to confirm the results of sc-RNA seq analysis.

RESULTS

For the Tibetan samples, the ratios of Naïve CD4 RPS4Y1 cells, Naïve CD4 cells, Memory BC CD24 and Memory BC differed significantly between the SLE and control samples, while that of CD8 CTL MAL cells was significantly different between the two groups in Han nationality samples. Variable differentiation states of CD8 CTL MAL cells, CD8 CTL GZMK cells, and Naïve CD4 cells were detected through pseudotime analysis. Moreover, T-cell receptor (TCR) abundance was notably higher in Tibetan SLE specimens than that in controls, while B-cell receptor (BCR) abundance in Tibetan and Han samples was higher than in control groups.

CONCLUSIONS

In summary, the immune cellular heterogeneity of SLE patients both Han and Zang nationality was explored based on various bioinformatics approaches, providing new perspectives for immunological characteristics of SLE among different ethnic groups.

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.

The Autoimmune Rheumatic Disease Related Dry Eye and Its Association with Retinopathy

Dry eye disease is a chronic disease of the ocular surface characterized by abnormal tear film composition, tear film instability, and ocular surface inflammation, affecting 5% to 50% of the population worldwide. Autoimmune rheumatic diseases (ARDs) are systemic disorders with multi-organ involvement, including the eye, and play a significant role in dry eye. To date, most studies have focused on Sjögren's syndrome (one of the ARDs) since it manifests as two of the most common symptoms-dry eyes and a dry mouth-and attracts physicians to explore the relationship between dry eye and ARDs. Many patients complained of dry eye related symptoms before they were diagnosed with ARDs, and ocular surface malaise is a sensitive indicator of the severity of ARDs. In addition, ARD related dry eye is also associated with some retinal diseases directly or indirectly, which are described in this review. This review also summarizes the incidence, epidemiological characteristics, pathogenesis, and accompanying ocular lesions of ARD's related dry eye, emphasizing the potential role of dry eye in recognition and monitoring among ARDs patients.

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.

Pediatric Systemic Lupus Erythematous in COVID-19 Era

Pediatric systemic lupus erythematosus is a chronic autoimmune disorder with a highly variable course and prognosis. It results in functional abnormalities in the immune system due to intrinsic factors and the use of immunosuppressive therapies associated with underlying comorbidities seem to increase the risk of severe COVID-19 and poor outcomes of the disease in pediatric systemic lupus erythematosus (SLE) patients. The aim of this review is to obtain a better understanding of the existing link between this new viral infection and pediatric lupus. We have analyzed the characteristics of newly diagnosed cases of pediatric SLE following COVID-19 which have been reported in the literature and which describe the impact that COVID-19 has on patients already suffering with pediatric SLE.

Lupus Nephritis: Current Perspectives and Moving Forward

Lupus nephritis is a severe organ manifestation of systemic lupus erythematosus, and its pathogenesis involves complex etiology and mechanisms. Despite significant knowledge gains and extensive efforts put into understanding the development and relapsing disease activity, lupus nephritis remains a substantial cause of morbidity and mortality in lupus patients. Current therapies retain a significant unmet medical need regarding rates of complete response, preventing relapse of lupus nephritis, progression of chronic kidney disease to kidney failure, drug toxicity, and pill burden-related drug non-adherence. Connected to progression of chronic kidney disease are the associated risks for disabling or even lethal cardiovascular events, as well as chronic kidney disease-related secondary immunodeficiency and serious infections. In this regard, biomarkers are needed that can predict treatment response to specific drugs to enable personalized precision medicine. A series of clinical trials with innovative immunomodulatory drugs are ongoing and raise expectations for improvements in the management of lupus nephritis. Here, we review how new developments in pathogenesis connect with current and future perspectives for the management of lupus nephritis.

Defining the characteristics of interferon-alpha-stimulated human genes: insight from expression data and machine learning

BACKGROUND

A virus-infected cell triggers a signalling cascade, resulting in the secretion of interferons (IFNs), which in turn induces the upregulation of the IFN-stimulated genes (ISGs) that play a role in antipathogen host defence. Here, we conducted analyses on large-scale data relating to evolutionary gene expression, sequence composition, and network properties to elucidate factors associated with the stimulation of human genes in response to IFN-α.

RESULTS

We find that ISGs are less evolutionary conserved than genes that are not significantly stimulated in IFN experiments (non-ISGs). ISGs show obvious depletion of GC content in the coding region. This influences the representation of some compositions following the translation process. IFN-repressed human genes (IRGs), downregulated genes in IFN experiments, can have similar properties to the ISGs. Additionally, we design a machine learning framework integrating the support vector machine and novel feature selection algorithm that achieves an area under the receiver operating characteristic curve (AUC) of 0.7455 for ISG prediction. Its application in other IFN systems suggests the similarity between the ISGs triggered by type I and III IFNs.

CONCLUSIONS

ISGs have some unique properties that make them different from the non-ISGs. The representation of some properties has a strong correlation with gene expression following IFN-α stimulation, which can be used as a predictive feature in machine learning. Our model predicts several genes as putative ISGs that so far have shown no significant differential expression when stimulated with IFN-α in the cell/tissue types in the available databases. A web server implementing our method is accessible at http://isgpre.cvr.gla.ac.uk/. The docker image at https://hub.docker.com/r/hchai01/isgpre can be downloaded to reproduce the prediction.

Lupus, DNA Methylation, and Air Pollution: A Malicious Triad

The pathogenesis of systemic lupus erythematosus (SLE) remains elusive to this day; however, genetic, epigenetic, and environmental factors have been implicated to be involved in disease pathogenesis. Recently, it was demonstrated that in systemic lupus erythematosus (SLE) patients, interferon-regulated genes are hypomethylated in naïve CD4⁺ T cells, CD19⁺ B lymphocytes, and CD14⁺ monocytes. This suggests that interferon-regulated genes may have been epigenetically poised in SLE patients for rapid expression upon stimulation by different environmental factors. Additionally, environmental studies have identified DNA (hypo)methylation changes as a potential mechanism of environmentally induced health effects in utero, during childhood and in adults. Finally, epidemiologic studies have firmly established air pollution as a crucial SLE risk factor, as studies showed an association between fine particulate matter (PM_2.5) and traditional SLE biomarkers related to disease flare, hospital admissions, and an increased SLEDAI score. In this review, the relationship between aberrant epigenetic regulation, the environment, and the development of SLE will be discussed.

IFI44 is an immune evasion biomarker for SARS-CoV-2 and Staphylococcus aureus infection in patients with RA

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global pandemic of severe coronavirus disease 2019 (COVID-19). Staphylococcus aureus is one of the most common pathogenic bacteria in humans, rheumatoid arthritis (RA) is among the most prevalent autoimmune conditions. RA is a significant risk factor for SARS-CoV-2 and S. aureus infections, although the mechanism of RA and SARS-CoV-2 infection in conjunction with S. aureus infection has not been elucidated. The purpose of this study is to investigate the biomarkers and disease targets between RA and SARS-CoV-2 and S. aureus infections using bioinformatics analysis, to search for the molecular mechanisms of SARS-CoV-2 and S. aureus immune escape and potential drug targets in the RA population, and to provide new directions for further analysis and targeted development of clinical treatments.

Methods

The RA dataset (GSE93272) and the S. aureus bacteremia (SAB) dataset (GSE33341) were used to obtain differentially expressed gene sets, respectively, and the common differentially expressed genes (DEGs) were determined through the intersection. Functional enrichment analysis utilizing GO, KEGG, and ClueGO methods. The PPI network was created utilizing the STRING database, and the top 10 hub genes were identified and further examined for functional enrichment using Metascape and GeneMANIA. The top 10 hub genes were intersected with the SARS-CoV-2 gene pool to identify five hub genes shared by RA, COVID-19, and SAB, and functional enrichment analysis was conducted using Metascape and GeneMANIA. Using the NetworkAnalyst platform, TF-hub gene and miRNA-hub gene networks were built for these five hub genes. The hub gene was verified utilizing GSE17755, GSE55235, and GSE13670, and its effectiveness was assessed utilizing ROC curves. CIBERSORT was applied to examine immune cell infiltration and the link between the hub gene and immune cells.

Results

A total of 199 DEGs were extracted from the GSE93272 and GSE33341 datasets. KEGG analysis of enrichment pathways were NLR signaling pathway, cell membrane DNA sensing pathway, oxidative phosphorylation, and viral infection. Positive/negative regulation of the immune system, regulation of the interferon-I (IFN-I; IFN-α/β) pathway, and associated pathways of the immunological response to viruses were enriched in GO and ClueGO analyses. PPI network and Cytoscape platform identified the top 10 hub genes: RSAD2, IFIT3, GBP1, RTP4, IFI44, OAS1, IFI44L, ISG15, HERC5, and IFIT5. The pathways are mainly enriched in response to viral and bacterial infection, IFN signaling, and 1,25-dihydroxy vitamin D3. IFI44, OAS1, IFI44L, ISG15, and HERC5 are the five hub genes shared by RA, COVID-19, and SAB. The pathways are primarily enriched for response to viral and bacterial infections. The TF-hub gene network and miRNA-hub gene network identified YY1 as a key TF and hsa-mir-1-3p and hsa-mir-146a-5p as two important miRNAs related to IFI44. IFI44 was identified as a hub gene by validating GSE17755, GSE55235, and GSE13670. Immune cell infiltration analysis showed a strong positive correlation between activated dendritic cells and IFI44 expression.

Conclusions

IFI144 was discovered as a shared biomarker and disease target for RA, COVID-19, and SAB by this study. IFI44 negatively regulates the IFN signaling pathway to promote viral replication and bacterial proliferation and is an important molecular target for SARS-CoV-2 and S. aureus immune escape in RA. Dendritic cells play an important role in this process. 1,25-Dihydroxy vitamin D3 may be an important therapeutic agent in treating RA with SARS-CoV-2 and S. aureus infections.

Menthone inhibits type-I interferon signaling by promoting Tyk2 ubiquitination to relieve local inflammation of rheumatoid arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease. RA development is mediated by the abnormal activation of multiple signaling pathways. Recent studies have revealed that type-I interferon (IFN-I) signaling plays an essential role in the occurrence and development of RA. However, how to target IFN-I signaling to develop anti-rheumatoid arthritis drugs remains largely unexplored. Here, our study showed that IFN-I signaling was over-activated in articular synovial cells from collagen II-induced arthritis (CIA) mice. Interestingly, we found that a small molecule compound, menthone, strongly inhibited the activation of the IFN-I signaling pathway. Further studies revealed that menthone promoted K48-linked polyubiquitination of Tyk2, thus lowering the protein level and stability of Tyk2. Importantly, menthone administration in the local articulus of CIA mice significantly attenuated the local inflammation in CIA mice. This study could promote our understanding of rheumatoid arthritis, and also suggests a potential strategy to develop anti-RA drugs.

New onset systemic lupus erythematosus after COVID-19 infection: a case report

COVID-19 is a respiratory viral illness that can have life threatening complications. While the short-term sequela of COVID-19, including cytokine storm, is relatively well known, the long-term complications of COVID-19 infection on the immune system is still unknown. There have been some reported cases of autoimmune disease development after COVID-19 infection. We present a patient with a history of COVID-19 infection one month prior who presented with non-specific symptoms including fatigue, malaise, bilateral lower extremity swelling and shortness of breath. His laboratory evaluation and physical exam showed him to be in acute renal failure. Further workup and kidney biopsy results confirmed systemic lupus erythematosus (SLE). Our patient needed treatment with plasmapheresis and immunosuppressants, and subsequently had significant improvement in his symptoms. We discuss the current 2019 European Alliance of Associations for Rheumatology/American College of Rheumatology (EULAR/ACR) diagnostic criteria for SLE and describe plausible mechanisms of COVID-19 induced lupus such as B-cell activation by the virus. We also explore the role of interferons in the potential development of autoimmune diseases after COVID-19 infection and highlight the need for further research in the area.

ISGylation is increased in the peripheral blood mononuclear cells derived from symptomatic COVID-19 patients

Cytokine-driven hyper inflammation has been identified as a critical factor behind poor outcomes in patients severely infected with SARS-CoV-2 virus. Notably, protein ISGylation, a protein conjugated form of Type 1 IFN-inducible ubiquitin-like protein ISG15 (Interferon-Stimulated Gene 15), induces cytokine storm (CS) and augments colonic inflammation in colitis-associated colon cancers in mouse models. However, whether ISGylation is increased and causally responsible for CS and hyper inflammation in symptomatic COVID-19 patients is unknown. Here, we measured ISGylation levels in peripheral blood mononuclear cells (PBMCs) from 10 symptomatic (SARS-CoV-2-positive with symptoms) and asymptomatic (SARS-CoV-2-positive with no symptoms) COVID-19 patients, and 4 uninfected individuals (SARS-CoV-2-negative), using Wes^Tm assay. Strikingly, we note significant increases in protein ISGylation and MX-1 (myxovirus-resistance protein-1) protein levels, both induced by type-I IFN, in symptomatic but not in asymptomatic patients and uninfected individuals. Knowing that ISGylation augments CS and intestinal inflammation in colon cancers, we propose that increased ISGylation may be an underlying cause of CS and inflammation in symptomatic patients.

Autoimmunity in Wiskott-Aldrich Syndrome: Updated Perspectives

Wiskott–Aldrich syndrome (WAS) is an uncommon X-linked combined-immunodeficiency disorder characterized by a triad of thrombocytopenia, eczema, and immunodeficiency. Patients with WAS are also predisposed to autoimmunity and malignancy. Autoimmune manifestations have been reported in 26%–72% of patients with WAS. Autoimmunity is an independent predictor of poor prognosis and predisposes to malignancy. Development of autoimmunity is also an early pointer of the need for hematopoietic stem–cell transplantation. In this manuscript, we have collated the published data and present a narrative review on autoimmune manifestations in WAS. A summary of currently proposed immunopathogenic mechanisms and genetic variants associated with development of autoimmunity in WAS is also included.

Decoding the dynamics of multilayered stochastic antiviral IFN-I responses

Type I Interferon (IFN-I) responses were first recognized for their role in antiviral immunity, but it is now widely appreciated that IFN-Is have many immunomodulatory functions, influencing antitumor responses, autoimmune manifestations, and antimicrobial defenses. Given these pivotal roles, it may be surprising that multilayered stochastic events create highly heterogeneous, but tightly regulated, all-or-nothing cellular decisions. Recently, mathematical models have provided crucial insights into the stochastic nature of antiviral IFN-I responses, which we critically evaluate in this review. In this context, we emphasize the need for innovative single-cell technologies combined with mathematical models to further reveal, understand, and predict the complexity of the IFN-I system in physiological and pathological conditions that may be relevant to a plethora of diseases.

Plasmacytoid Dendritic Cells as a New Therapeutic Target for Autoimmune Pancreatitis and IgG4-Related Disease

Although plasmacytoid dendritic cells (pDCs) able to produce large amounts of type 1 interferons (IFN-I) play beneficial roles in host defense against viral infections, excessive activation of pDCs, followed by robust production of IFN-I, causes autoimmune disorders including systemic lupus erythematosus (SLE) and psoriasis. Autoimmune pancreatitis (AIP), which is recognized as a pancreatic manifestation of systemic immunoglobulin G4-related disease (IgG4-RD), is a chronic fibroinflammatory disorder driven by autoimmunity. IgG4-RD is a multi-organ autoimmune disorder characterized by elevated serum concentrations of IgG4 antibody and infiltration of IgG4-expressing plasmacytes in the affected organs. Although the immunopathogenesis of IgG4-RD and AIP has been poorly elucidated, recently, we found that activation of pDCs mediates the development of murine experimental AIP and human AIP/IgG4-RD via the production of IFN-I and interleukin-33 (IL-33). Depletion of pDCs or neutralization of signaling pathways mediated by IFN-I and IL-33 efficiently inhibited the development of experimental AIP. Furthermore, enhanced expression of IFN-I and IL-33 was observed in the pancreas and serum of human AIP/IgG4-RD. Thus, AIP and IgG4-RD share their immunopathogenesis with SLE and psoriasis because in all these conditions, IFN-I production by pDCs contributes to the pathogenesis. Because the enhanced production of IFN-I and IL-33 by pDCs promotes chronic inflammation and fibrosis characteristic for AIP and IgG4-RD, neutralization of IFN-I and IL-33 could be a new therapeutic option for these disorders. In this Mini Review, we discuss the pathogenic roles played by the pDC-IFN-I-IL-33 axis and the development of a new treatment targeting this axis in AIP and IgG4-RD.

Analysis of interferon type I signature for differential diagnosis of diseases of the immune system ( review of literature)

Type 1 interferons (IFN1) are both key molecules of antiviral defense and potent inflammatory mediators. In 2003, increased expression of a variety of interferon 1-regulated genes was observed in a blood cells of patients with systemic lupus erythematosus (SLE). This phenomenon was called the type 1 interferon signature (IFN1-signature). Since then, expression patterns indicating the presence of an IFN1-signature were consistently detected in a range of monogenic and complex autoimmune and autoinflammatory conditions. A quantitative indicator reflecting the degree of hyperactivation of the IFN1 pathway is known as interferon score. This review discusses the possible causes of upregulated expression of interferon 1-induced genes, the laboratory approaches to the interferon score analysis, as well as the practical use of this indicator for the diagnosis of various conditions.

The gene silencing of IRF5 and BLYSS effectively modulates the outcome of experimental lupus nephritis

Systemic lupus erythematosus is a highly complex and heterogeneous autoimmune disease mostly mediated by B cells. It is characterized by circulating self-reactive antibodies that deposit and form immune complexes in kidney, leading to irreparable tissue damage and resulting in lupus nephritis. In a New Zealand Black X New Zealand White F1 mouse model, we tested two different small interfering RNA (siRNA) silencing treatments against interferon regulatory factor 5 (IRF5) and B cell-activating factor (BLYSS) expression and their combination in a second set of animals. The administration of these two siRNAs separately prevented the progression of proteinuria and albuminuria at similar levels to that in cyclophosphamide animals. These treatments effectively resulted in a reduction of serum anti-double-stranded DNA (dsDNA) antibodies and histopathological renal score compared with non-treated group. Treated groups showed macrophage, T cell, and B cell infiltrate reduction in renal tissue. Moreover, kidney gene expression analysis revealed that siRNA treatments modulated very few pathways in contrast to cyclophosphamide, despite showing similar therapeutic effects. Additionally, the combined therapy tested in a second set of animals, in which the disease appeared more virulent, exhibited better results than monotherapies in the disease progression, delaying the disease onset and ameliorating the disease outcome. Herein, we provide the potential therapeutic effect of both selective IRF5 and BLYSS silencing as an effective and potential treatment, particularly in early phases of the disease.

Roles of Genetic Predisposition in the Sex Bias of Pulmonary Pathophysiology, as a Function of Estrogens : Sex Matters in the Prevalence of Lung Diseases

In addition to studies focused on estrogen mediation of sex-different regulation of systemic circulations, there is now increasing clinical relevance and research interests in the pulmonary circulation, in terms of sex differences in the morbidity and mortality of lung diseases such as inherent-, allergic- and inflammatory-based events. Thus, female predisposition to pulmonary artery hypertension (PAH) is an inevitable topic. To better understand the nature of sexual differentiation in the pulmonary circulation, and how heritable factors, in vivo- and/or in vitro-altered estrogen circumstances and changes in the live environment work in concert to discern the sex bias, this chapter reviews pulmonary events characterized by sex-different features, concomitant with exploration of how alterations of genetic expression and estrogen metabolisms trigger the female-predominant pathological signaling. We address the following: PAH (Sect.7.2) is characterized as an estrogenic promotion of its incidence (Sect. 7.2.2), as a function of specific germline mutations, and as an estrogen-elicited protection of its prognosis (Sect.7.2.1). More detail is provided to introduce a less recognized gene of Ephx2 that encodes soluble epoxide hydrolase (sEH) to degrade epoxyeicosatrienic acids (EETs). As a susceptible target of estrogen, Ephx2/sEH expression is downregulated by an estrogen-dependent epigenetic mechanism. Increases in pulmonary EETs then evoke a potentiation of PAH generation, but mitigation of its progression, a phenomenon similar to the estrogen-paradox regulation of PAH. Additionally, the female susceptibility to chronic obstructive pulmonary diseases (Sect. 7.3) and asthma (Sect.7.4), but less preference to COVID-19 (Sect. 7.5), and roles of estrogen in their pathogeneses are briefly discussed.

Azithromycin and glucosamine may amplify the type 1 interferon response to RNA viruses in a complementary fashion

Previous research demonstrates that, in clinically relevant concentrations, azithromycin can boost the ability of RNA viruses to induce type 1 interferon by amplifying the expression and virally-mediated activation of MDA5. O-GlcNAcylation of MAVS, a down-stream target of MDA5, renders it more effective for type 1 interferon induction. High-dose glucosamine administration up-regulates O-GlcNAcylation by increasing the cellular pool of UDP-N-acetylglucosamine. Hence, it is proposed that joint administration of azithromycin and high-dose glucosamine, early in the course of RNA virus infections, may interact in a complementary fashion to aid their control by enhancing type 1 interferon induction.

Oxidative DNA Damage Accelerates Skin Inflammation in Pristane-Induced Lupus Model

Systemic Lupus Erythematosus (SLE) is a chronic inflammatory autoimmune disease in which type I interferons (IFN) play a key role. The IFN response can be triggered when oxidized DNA engages the cytosolic DNA sensing platform cGAS-STING, but the repair mechanisms that modulate this process and govern disease progression are unclear. To gain insight into this biology, we interrogated the role of oxyguanine glycosylase 1 (OGG1), which repairs oxidized guanine 8-Oxo-2'-deoxyguanosine (8-OH-dG), in the pristane-induced mouse model of SLE. Ogg1 ^-/- mice showed increased influx of Ly6C^hi monocytes into the peritoneal cavity and enhanced IFN-driven gene expression in response to short-term exposure to pristane. Loss of Ogg1 was associated with increased auto-antibodies (anti-dsDNA and anti-RNP), higher total IgG, and expression of interferon stimulated genes (ISG) to longer exposure to pristane, accompanied by aggravated skin pathology such as hair loss, thicker epidermis, and increased deposition of IgG in skin lesions. Supporting a role for type I IFNs in this model, skin lesions of Ogg1 ^-/- mice had significantly higher expression of type I IFN genes (Isg15, Irf9, and Ifnb). In keeping with loss of Ogg1 resulting in dysregulated IFN responses, enhanced basal and cGAMP-dependent Ifnb expression was observed in BMDMs from Ogg1 ^-/- mice. Use of the STING inhibitor, H151, reduced both basal and cGAMP-driven increases, indicating that OGG1 regulates Ifnb expression through the cGAS-STING pathway. Finally, in support for a role for OGG1 in the pathology of cutaneous disease, reduced OGG1 expression in monocytes associated with skin involvement in SLE patients and the expression of OGG1 was significantly lower in lesional skin compared with non-lesional skin in patients with Discoid Lupus. Taken together, these data support an important role for OGG1 in protecting against IFN production and SLE skin disease.

Small Heterodimer Partner Controls the Virus-Mediated Antiviral Immune Response by Targeting CREB-Binding Protein in the Nucleus

Small heterodimer partner (SHP) is an orphan nuclear receptor that acts as a transcriptional co-repressor by interacting with nuclear receptors and transcription factors. Although SHP plays a negative regulatory function in various signaling pathways, its role in virus infection has not been studied. Here, we report that SHP is a potent negative regulator of the virus-mediated type I IFN signaling that maintains homeostasis within the antiviral innate immune system. Upon virus infection, SHP interacts specifically with CREB-binding protein (CBP) in the nucleus, thereby obstructing CBP/β-catenin interaction competitively. Consequently, SHP-deficient cells enhance antiviral responses, including transcription of the type I IFN gene, upon virus infection. Furthermore, SHP-deficient mice show higher levels of IFN production and are more resistant to influenza A virus infection. Our results suggest that SHP is a nuclear regulator that blocks transcription of the type I IFN gene to inhibit excessive innate immune responses.

Upstream ORFs Prevent MAVS Spontaneous Aggregation and Regulate Innate Immune Homeostasis

The monomer-to-filament transition of MAVS is essential for the RIG-I/MDA5-mediated antiviral signaling. In quiescent cells, monomeric MAVS is under strict regulation for preventing its spontaneous aggregation, which would result in dysregulated interferon (IFN-α/β) production and autoimmune diseases like systemic lupus erythematosus. However, the detailed mechanism by which MAVS is kept from spontaneous aggregation remains largely unclear. Here, we show that upstream open reading frames (uORFs) within the MAVS transcripts exert a post-transcriptional regulation for preventing MAVS spontaneous aggregation and auto-activation. Mechanistically, we demonstrate that uORFs are cis-acting elements initiating leaky ribosome scanning of the downstream ORF codons, thereby repressing the full-length MAVS translation. We further uncover that endogenous MAVS generated from the uORF-deprived transcript spontaneously aggregates, triggering the Nix-mediated mitophagic clearance of damaged mitochondria and aggregated MAVS. Our findings reveal the uORF-mediated quantity and quality control of MAVS, which prevents aberrant protein aggregation and maintains innate immune homeostasis.

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uORFs are safety checks preventing MAVS spontaneous aggregation and auto-activation

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uORFs exert the quantity and quality control of MAVS

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Spontaneously aggregated MAVS induces an antiviral state in quiescent cells

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Nix mediates the cargo selection and mitophagic clearance of MAVS aggregates

STAT4: an immunoregulator contributing to diverse human diseases

Signal transducer and activator of transcription 4 (STAT4) is a member of the STAT family and localizes to the cytoplasm. STAT4 is phosphorylated after a variety of cytokines bind to the membrane, and then dimerized STAT4 translocates to the nucleus to regulate gene expression. We reviewed the essential role played by STAT4 in a wide variety of cells and the pathogenesis of diverse human diseases, especially many kinds of autoimmune and inflammatory diseases, via activation by different cytokines through the Janus kinase (JAK)-STAT signaling pathway.

Primary Sjögren's syndrome and the eye

Primary Sjögren syndrome is an autoimmune disease that mainly affects exocrine glands such as the salivary and lacrimal glands. In addition, systemic involvement is common. Primary Sjögren syndrome is of particular interest to ophthalmologists as it constitutes an important differential diagnosis in conditions with dry eye disease. In addition, ocular tests for more precisely diagnosing and monitoring primary Sjögren syndrome have become increasingly important, and new therapeutics for local and systemic treatment evolve as a result of increased understanding of immunological mechanisms and molecular pathways in the pathogenesis of primary Sjögren syndrome. We provide an update of interest to ophthalmologists regarding pathogenesis, diagnosis, investigative procedures, and treatment options.

Cutaneous lupus erythematosus: new insights into pathogenesis and therapeutic strategies

Cutaneous lupus erythematosus (CLE) is an autoimmune disease that can present as an isolated skin disease or as a manifestation within the spectrum of systemic lupus erythematosus. The clinical spectrum of CLE is broad, ranging from isolated discoid plaques to widespread skin lesions. Histologically, skin lesions present as interface dermatitis (inflammation of the skin mediated by anti-epidermal responses), which is orchestrated by type I and type III interferon-regulated cytokines and chemokines. Both innate and adaptive immune pathways are strongly activated in the formation of skin lesions owing to continuous re-activation of innate pathways via pattern recognition receptors (PRRs). These insights into the molecular pathogenesis of skin lesions in CLE have improved our understanding of the mechanisms underlying established therapies and have triggered the development of targeted treatment strategies that focus on immune cells (for example, B cells, T cells or plasmacytoid dendritic cells), as well as immune response pathways (for example, PRR signalling, Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signalling and nuclear factor-κB signalling) and their cytokines and chemokines (for example, type I interferons, CXC-chemokine ligand 10 (CXCL10), IL-6 and IL-12).

Silica exposure and chronic virus infection synergistically promote lupus-like systemic autoimmunity in mice with low genetic predisposition

Considerable evidence indicates that autoimmune disease expression depends on both genetic and environmental factors. Among potential environmental triggers, occupational airway exposure to crystalline silica and virus infections have been linked to lupus and other autoimmune diseases in both humans and mouse models. Here, we hypothesized that combined silica and virus exposures synergize and induce autoimmune manifestations more effectively than single exposure to either of these factors, particularly in individuals with low genetic predisposition. Accordingly, infection with the model murine pathogen lymphocytic choriomenigitis virus (LCMV) in early life, followed by airway exposure to crystalline silica in adult life, induced lupus-like autoantibodies to several nuclear self-antigens including chromatin, RNP and Sm, concurrent with kidney lesions, in non-autoimmune C57BL/6 (B6) mice. In contrast, given individually, LCMV or silica were largely ineffectual in this strain. These results support a multihit model of autoimmunity, where exposure to different environmental factors acting on distinct immunostimulatory pathways complements limited genetic predisposition and increases the risk of autoimmunity above a critical threshold.

Coordination between innate immune cells, type I IFNs and IRF5 drives SLE pathogenesis

Systemic lupus erythematosus (SLE) is a complex autoimmune disease which affects multiple organs. The type I interferon (IFN) gene signature and circulating autoantibodies are hallmarks of SLE. Plasmacytoid dendritic cells (pDCs) are considered the main producers of type I IFN and production is modulated by multiple other immune cell types. In SLE, essentially every immune cell type is dysregulated and aberrant deregulation is thought to be due, in part, to direct or indirect exposure to IFN. Genetic variants within or around the transcription factor interferon regulatory factor 5 (IRF5) associate with SLE risk. Elevated IFNα activity was detected in the sera of SLE patients carrying IRF5 risk polymorphisms who were positive for either anti-RNA binding protein (anti-RBP) or anti-double-stranded DNA (anti-dsDNA) autoantibodies. Neutrophils are also an important source of type I IFNs and are found in abundance in human blood. Neutrophil extracellular traps (NETs) are considered a potential source of antigenic trigger in SLE that can lead to type I IFN gene induction, as well as increased autoantibody production. In this review, we will focus on immune cell types that produce type I IFNs and/or are affected by type I IFN in SLE. In addition, we will discuss potential inducers of endogenous type I IFN production in SLE. Last, we will postulate how the different immune cell populations may be affected by an IRF5-SLE risk haplotype.

An alternatively transcribed TAZ variant negatively regulates JAK-STAT signaling

Type I interferon (IFN)-induced Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling drives the expression of IFN-stimulated genes (ISGs) to mediate antiviral response. The strength and duration of JAK-STAT signaling are tightly regulated to ensure effective antiviral defense while avoiding pathological inflammation and autoimmunity. Here, we report that cTAZ, an isoform of the Hippo pathway effector TAZ, is transcribed by an alternative promoter. Although majority of C-terminal sequences of TAZ is retained, cTAZ is not regulated by the Hippo signaling and does not mediate its growth-inhibitory functions. Instead, cTAZ negatively regulates JAK-STAT signaling by inhibiting STAT1/2 nuclear localization and ISG expression, and its expression is induced by type I IFN Thus, cTAZ functions as a modulator of JAK-STAT signaling and may play a role in fine-tuning cellular antiviral response.

Safety and tolerability of anifrolumab, a monoclonal antibody targeting type I interferon receptor, in Japanese patients with systemic lupus erythematosus: A multicenter, phase 2, open-label study

Objectives: This study evaluated the safety and tolerability of anifrolumab, a monoclonal antibody targeting the type I interferon (IFN) receptor, in Japanese patients with moderate-to-severe systemic lupus erythematosus (SLE).Methods: In this open-label, phase 2, dose-escalation study, patients received intravenous (IV) anifrolumab 100, 300, or 1000 mg every 4 weeks from days 29 to 337 (Stage 1). Patients who completed Stage 1 continued anifrolumab 300 mg every 4 weeks for 156 weeks (Stage 2). The primary objective was to evaluate the safety of anifrolumab for 48 weeks (Stage 1) and 156 weeks (Stage 2). The pharmacokinetics and pharmacodynamics of anifrolumab were also assessed.Results: Of 20 patients enrolled in Stage 1, 17 received IV anifrolumab 100 mg (n = 6), 300 mg (n = 5), or 1000 mg (n = 6). Adverse events (AE) and serious AE (SAE) incidences were similar between dose cohorts. SAEs occurred in 41% (Stage 1) and 33% (Stage 2) of patients; AEs leading to discontinuation occurred in 24% (Stage 1) and 22% (Stage 2) of patients. Anifrolumab had non-linear pharmacokinetics after the first and last dose and dose-dependently suppressed the IFN gene signature.Conclusion: Anifrolumab was well tolerated among Japanese patients with moderate-to-severe SLE.

Depletion of MicroRNA-373 Represses the Replication of Hepatitis C Virus via Activation of Type 1 Interferon Response by Targeting IRF5

PURPOSE

Hepatitis C virus (HCV) poses a risk of chronic liver disease and threatens a significant number of people worldwide. MicroRNAs (miRNAs) are linked to the regulation of hepatocarcinogenesis. Although miR-373 is required for HCV infection, the underlying mechanisms of miR-373 involvement in HCV replication remain elusive.

MATERIALS AND METHODS

Quantitative reverse transcription PCR assays were performed to detect the abundances of miR-373 and HCV RNA either in Huh 7.5 cells or liver biopsy specimens with HCV infection. Luciferase assay was employed to probe the interactions between miR-373 and interferon regulatory factor 5 (IRF5). Western blot was conducted to investigate the effect of miR-373 and IRF5 on HCV replication and activation of type 1 interferon (IFN) response in JFH1-infected Huh 7.5 cells.

RESULTS

HCV infection appeared to be caused by increased miR-373 expression. Addition of miR-373 promoted HCV RNA expression, while miR-373 depletion led to an inhibitive effect on HCV replication. Concordantly, IRF5, as a direct target, was limited by miR-373 in JFH1-infected Huh 7.5 cells. In addition, introduction of IRF5 protected HCV replication in the presence of abundant miR-373. Furthermore, the miR-373-mediated inhibitory effect on type 1 IFN response was ablated following IRF5 accumulation.

CONCLUSION

miR-373 abrogation reduced HCV replication via activation of type 1 IFN responses by targeting IRF5 in JFH1-infected Huh 7.5 cells, suggesting a promising therapeutic for treating HCV infection.

Female predisposition to TLR7-driven autoimmunity: gene dosage and the escape from X chromosome inactivation

Women develop stronger immune responses than men, with positive effects on the resistance to viral or bacterial infections but magnifying also the susceptibility to autoimmune diseases like systemic lupus erythematosus (SLE). In SLE, the dosage of the endosomal Toll-like receptor 7 (TLR7) is crucial. Murine models have shown that TLR7 overexpression suffices to induce spontaneous lupus-like disease. Conversely, suppressing TLR7 in lupus-prone mice abolishes SLE development. TLR7 is encoded by a gene on the X chromosome gene, denoted TLR7 in humans and Tlr7 in the mouse, and expressed in plasmacytoid dendritic cells (pDC), monocytes/macrophages, and B cells. The receptor recognizes single-stranded RNA, and its engagement promotes B cell maturation and the production of pro-inflammatory cytokines and antibodies. In female mammals, each cell randomly inactivates one of its two X chromosomes to equalize gene dosage with XY males. However, 15 to 23% of X-linked human genes escape X chromosome inactivation so that both alleles can be expressed simultaneously. It has been hypothesized that biallelic expression of X-linked genes could occur in female immune cells, hence fostering harmful autoreactive and inflammatory responses. We review here the current knowledge of the role of TLR7 in SLE, and recent evidence demonstrating that TLR7 escapes from X chromosome inactivation in pDCs, monocytes, and B lymphocytes from women and Klinefelter syndrome men. Female B cells where TLR7 is thus biallelically expressed display higher TLR7-driven functional responses, connecting the presence of two X chromosomes with the enhanced immunity of women and their increased susceptibility to TLR7-dependent autoimmune syndromes.

Lupus acceleration by a MAVS-activating RNA virus requires endosomal TLR signaling and host genetic predisposition

Viruses have long been implicated in the pathogenesis of autoimmunity, yet their contribution remains circumstantial partly due to the lack of well-documented information on infections prior to autoimmune disease onset. Here, we used the lymphocytic choriomeningitis virus (LCMV) as a model to mechanistically dissect the impact of viral infection on lupus-like autoimmunity. Virus persistence strongly enhanced disease in mice with otherwise weak genetic predisposition but not in highly predisposed or non-autoimmune mice, indicating a synergistic interplay between genetic susceptibility and virus infection. Moreover, endosomal Toll-like receptors (TLRs) and plasmacytoid dendritic cells (pDCs) were both strictly required for disease acceleration, even though LCMV also induces strong TLR-independent type I interferon (IFN-I) production via RNA helicases and MAVS in conventional DCs. These results suggest that LCMV enhances systemic autoimmunity primarily by providing stimulatory nucleic acids for endosomal TLR engagement, whereas overstimulation of the MAVS-dependent cytosolic pathway in the absence of endosomal TLR signaling is insufficient for disease induction.

The multiple pathways to autoimmunity

Efforts to understand autoimmunity have been pursued relentlessly for several decades. It has become apparent that the immune system evolved multiple mechanisms for controlling self-reactivity, and defects in one or more of these mechanisms can lead to a breakdown of tolerance. Among the multitude of lesions associated with disease, the most common seem to affect peripheral tolerance rather than central tolerance. The initial trigger for both systemic autoimmune disorders and organ-specific autoimmune disorders probably involves the recognition of self or foreign molecules, especially nucleic acids, by innate sensors. Such recognition, in turn, triggers inflammatory responses and the engagement of previously quiescent autoreactive T cells and B cells. Here we summarize the most prominent autoimmune pathways and identify key issues that require resolution for full understanding of pathogenic autoimmunity.

Btk-specific inhibition blocks pathogenic plasma cell signatures and myeloid cell-associated damage in IFN-driven lupus nephritis

Systemic lupus erythematosus (SLE) is often associated with exaggerated B cell activation promoting plasma cell generation, immune-complex deposition in the kidney, renal infiltration of myeloid cells, and glomerular nephritis. Type-I IFNs amplify these autoimmune processes and promote severe disease. Bruton's tyrosine kinase (Btk) inhibitors are considered novel therapies for SLE. We describe the characterization of a highly selective reversible Btk inhibitor, G-744. G-744 is efficacious, and superior to blocking BAFF and Syk, in ameliorating severe lupus nephritis in both spontaneous and IFNα-accelerated lupus in NZB/W_F1 mice in therapeutic regimens. Selective Btk inhibition ablated plasmablast generation, reduced autoantibodies, and - similar to cyclophosphamide - improved renal pathology in IFNα-accelerated lupus. Employing global transcriptional profiling of spleen and kidney coupled with cross-species human modular repertoire analyses, we identify similarities in the inflammatory process between mice and humans, and we demonstrate that G-744 reduced gene expression signatures essential for splenic B cell terminal differentiation, particularly the secretory pathway, as well as renal transcriptional profiles coupled with myeloid cell-mediated pathology and glomerular plus tubulointerstitial disease in human glomerulonephritis patients. These findings reveal the mechanism through which a selective Btk inhibitor blocks murine autoimmune kidney disease, highlighting pathway activity that may translate to human SLE.

The Role of IFN-alpha in Experimental and Clinical Uveitis

PURPOSE

IFN-α is the only treatment capable of inducing long-term remission in some patients with ocular Behçet's disease. In this review, we focus on immune mechanisms of IFN-α in animal models and patients and compare the outcome of different clinical studies.

METHODS

Review of literature using PubMed and Google and original data from rat models with monophasic/chronic or relapsing experimental autoimmune uveitis treated with IFN-α.

RESULTS

The role of IFN-α and its effect on various cell types were investigated, in some cases with contradictory results. Some patients respond very well to IFN-α treatment, while others are non-responders, which was reflected in the uveitis rat models: relapsing uveitis was ameliorated, the monophasic/chronic disease even aggravated.

CONCLUSIONS

Despite intensive investigations in patients and animal models, the immune mechanisms explaining the therapeutic effect of IFN-α in ocular Behçet's disease are not yet fully understood and need further investigation.

AP-1 Expression and its Clinical Relevance in Immune Disorders and Cancer

The inflammatory response is known to have a significant role in certain autoimmune diseases and malignancies. We review current knowledge regarding the functions of activator protein 1 (AP-1) as an important modulator in several immune disorders and carcinomas. AP-1 is overexpressed in rheumatoid arthritis and in long-term allogeneic hematopoietic stem cell transplantation survivors; however, decreased expression of AP-1 has been observed in psoriasis, systematic lupus erythematosus and in patients who do not survive after hematopoietic stem cell transplantation. AP-1 also is implicated in the control of various cancer cells. Higher levels of AP-1 components are present in breast and endometrial carcinomas, colorectal cancer and in acute myeloid leukemia, Hodgkin׳s lymphoma and anaplastic large cell lymphoma, with downregulation in ovarian and gastric carcinomas and in patients with chronic myelogenous leukemia. AP-1 may enable the development of helpful markers to identify early-stage disease or to predict severity.

Autoantibody Specificities and Type I Interferon Pathway Activation in Idiopathic Inflammatory Myopathies

Myositis is a heterogeneous group of autoimmune diseases, with different pathogenic mechanisms contributing to the different subsets of disease. The aim of this study was to test whether the autoantibody profile in patients with myositis is associated with a type I interferon (IFN) signature, as in patients with systemic lupus erythematous (SLE). Patients with myositis were prospectively enrolled in the study and compared to healthy controls and to patients with SLE. Autoantibody status was analysed using an immunoassay system and immunoprecipitation. Type I IFN activity in whole blood was determined using direct gene expression analysis. Serum IFN-inducing activity was tested using peripheral blood cells from healthy donors. Blocking experiments were performed by neutralizing anti-IFNAR or anti-IFN-α antibodies. Patients were categorized into IFN high and IFN low based on an IFN score. Patients with autoantibodies against RNA-binding proteins had a higher IFN score compared to patients without these antibodies, and the IFN score was related to autoantibody multispecificity. Patients with dermatomyositis (DM) and inclusion body myositis (IBM) had a higher IFN score compared to the other subgroups. Serum type I IFN bioactivity was blocked by neutralizing anti-IFNAR or anti-IFN-α antibodies. To conclude, a high IFN score was not only associated with DM, as previously reported, and IBM, but also with autoantibody monospecificity against several RNA-binding proteins and with autoantibody multispecificity. These studies identify IFN-α in sera as a trigger for activation of the type I IFN pathway in peripheral blood and support IFN-α as a possible target for therapy in these patients.

Ubiquitin-dependent Turnover of Adenosine Deaminase Acting on RNA 1 (ADAR1) Is Required for Efficient Antiviral Activity of Type I Interferon

Adenosine deaminase acting on RNA 1 (ADAR1) catalyzes RNA editing of cellular and viral RNAs. Besides RNA editing, ADAR1 has recently been shown to play important roles in maintaining the body balance, including tissue homoeostasis, organ development, and autoimmune regulations, by inhibiting both IFN production and subsequent IFN-activated pathways. Accordingly, the question was raised how IFN signaling induced by viral infections overcomes the inhibitory effect of constitutively expressed ADAR1 (ADAR1-P110) to execute efficient antiviral activity. Here we unexpectedly found that IFN signaling promoted Lys⁴⁸-linked ubiquitination and degradation of ADAR1-P110. Furthermore, we identified the E3 ligase β transducin repeat-containing protein responsible for IFN-mediated ADAR1-P110 down-regulation. IFN signaling promoted the interaction between β transducin repeat-containing protein and ADAR1-P110 as well as protein turnover of ADAR1-P110. Moreover, we found that both lysine 574 and 576 are essential for ADAR1-P110 ubiquitination. Critically, we demonstrated that down-regulation of ADAR1-P110 is required for IFN signaling to execute efficient antiviral activity during viral infections. These findings renew the understanding of the mechanisms by which IFN signaling acts to achieve antiviral functions and may provide potential targets for IFN-based antiviral therapy.

Lupus brain fog: a biologic perspective on cognitive impairment, depression, and fatigue in systemic lupus erythematosus

Cognitive disturbances, mood disorders and fatigue are common in SLE patients with substantial adverse effects on function and quality of life. Attribution of these clinical findings to immune-mediated disturbances associated with SLE remains difficult and has compromised research efforts in these areas. Improved understanding of the role of the immune system in neurologic processes essential for cognition including synaptic plasticity, long term potentiation and adult neurogenesis suggests multiple potential mechanisms for altered central nervous system function associated with a chronic inflammatory illness such as SLE. This review will focus on the biology of cognition and neuroinflammation in normal circumstances and potential biologic mechanisms for cognitive impairment, depression and fatigue attributable to SLE.

Interferon-targeted therapy in systemic lupus erythematosus: Is this an alternative to targeting B and T cells?

Clinical trials of investigational agents in systemic lupus erythematosus (SLE) have focused on targeting dysregulated B and T cells; however, recent translational research findings of the importance of the dysregulation of the innate immune system in SLE have led to clinical trials that target interferon. Three biologics that target type I interferons have been tested for their efficacy and safety in active SLE patients; these phase II trials have tested the hypothesis that down-regulation of interferon-regulated gene expression (the interferon signature) lessen the clinical burden of SLE. Rontalizumab, an anti-interferon-α monoclonal antibody, was studied in patients who had discontinued immunosuppressants. This study failed to show efficacy as assessed by both two outcome assessments; however, in low interferon signature patients, response was higher and corticosteroid usage was less in rontalizumab-treated patients. Sifalimumab, another anti-interferon-α monoclonal antibody, was studied in patients who remained on standard of care therapy. This study showed significantly better efficacy in patients treated with two sifalimumab dosages; significant differences were seen in the high interferon signature group. In a similar design and in a similar population as the sifalimumab study, anifrolumab, a monoclonal antibody that binds to a type I interferon receptor, was studied in patients who remained on standard of care therapy. In this study, one dosage group demonstrated efficacy and statistically significant effects were achieved in both tested dosage groups with secondary end points. Oral corticosteroid reduction to ≤7.5 mg daily was achieved in one of the tested dosage groups and organ-specific outcomes were significantly improved in that same group. For all studies, no significant differences in serious adverse effects were seen; although, herpes zoster infections were increased in sifalimumab- and anifrolumab-treated patients and influenza rates were increased in anifrolumab-treated patients. Anifrolumab is currently in pivotal phase III studies. Data appear to support the concept that targeting type I interferon in SLE patients associates with clinical efficacy and safety. Further data are forthcoming from ongoing phase III clinical trials of anifrolumab. Other drug development efforts should be considered that target plasmacytoid dendritic cells and toll like receptors given the effects these components have on interferon production.

Induction of the type I interferon response in neurological forms of Gaucher disease

Background

Neuroinflammation is a key phenomenon in the pathogenesis of many neurodegenerative diseases. Understanding the mechanisms by which brain inflammation is engaged and delineating the key players in the immune response and their contribution to brain pathology is of great importance for the identification of novel therapeutic targets for these devastating diseases. Gaucher disease, the most common lysosomal storage disease, is caused by mutations in the GBA1 gene and is a significant risk factor for Parkinson’s disease; in some forms of Gaucher disease, neuroinflammation is observed.

Methods

An unbiased gene profile analysis was performed on a severely affected brain area of a neurological form of a Gaucher disease mouse at a pre-symptomatic stage; the mouse used for this study, the Gba^flox/flox; nestin-Cre mouse, was engineered such that GBA1 deficiency is restricted to cells of neuronal lineage, i.e., neurons and macroglia.

Results

The 10 most up-regulated genes in the ventral posteromedial/posterolateral region of the thalamus were inflammatory genes, with the gene expression signature significantly enriched in interferon signaling genes. Interferon β levels were elevated in neurons, and interferon-stimulated genes were elevated mainly in microglia. Interferon signaling pathways were elevated to a small extent in the brain of another lysosomal storage disease mouse model, Krabbe disease, but not in Niemann-Pick C or Sandhoff mouse brain. Ablation of the type I interferon receptor attenuated neuroinflammation but had no effect on GD mouse viability.

Conclusions

Our results imply that the type I interferon response is involved in the development of nGD pathology, and possibly in other lysosomal storage diseases in which simple glycosphingolipids accumulate, and support the notion that interferon signaling pathways play a vital role in the sterile inflammation that often occurs during chronic neurodegenerative diseases in which neuroinflammation is present.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0570-2) contains supplementary material, which is available to authorized users.

The assessment of serum-mediated phagocytosis of necrotic material by polymorphonuclear leukocytes to diagnose and predict the clinical features of systemic lupus erythematosus: an observational longitudinal study

BACKGROUND

Serum-mediated phagocytosis of antibody- and complement-opsonized necrotic cell material (NCM) by polymorphonuclear leukocytes can be quantified by using a flow cytometry-based assay. The phagocytosis of necrotic cell material (PNC) assay parallels the well-known lupus erythematosus cell test. In this study, we aimed to investigate the diagnostic accuracy of the assay and the relationship with clinical manifestations and disease activity in systemic lupus erythematosus (SLE).

METHODS

The diagnostic accuracy for SLE diagnosis of the PNC assay was studied by cross-sectional assessment of blood samples from 148 healthy control subjects and a multicenter rheumatic group (MRG) of 529 patients with different rheumatic symptoms. A cohort of 69 patients with an established SLE diagnosis (SLE cohort) underwent longitudinal clinical and laboratory follow-up for analysis of the temporal relationships between PNC positivity and specific clinical manifestations.

RESULTS

In 35 of 529 MRG patients, 13 of whom had SLE, the PNC assay result was positive. Combined positivity of the PNC assay and anti-double-stranded DNA antibodies increased specificity and positive predictive value for SLE diagnosis to 0.99 and 0.67, respectively. In the longitudinal study, 42 of 69 SLE cohort patients had positive results in the PNC assay at least once. PNC assay positivity was associated with current hematological manifestations and could predict mucocutaneous manifestations. When combined with hypocomplementemia, PNC positivity preceded increased Systemic Lupus Erythematosus Disease Activity Index 2000 score, glomerulonephritis, and alopecia.

CONCLUSIONS

Serum-mediated PNC by polymorphonuclear leukocytes is commonly but not exclusively seen in patients with SLE. The PNC assay may be used in follow-up of patients with SLE and, especially in combination with other routinely assessed laboratory tests, may help to predict flares and different clinical manifestations, including glomerulonephritis. Our results encourage further development of the PNC assay as a complementary laboratory tool in management of patients with SLE.

Expression of TLR-7, MyD88, NF-kB, and INF-α in B Lymphocytes of Mayan Women with Systemic Lupus Erythematosus in Mexico

Background

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease involving multiple organs. It is currently accepted that several genetic, environmental, and hormonal factors are contributing to its development. Innate immunity may have a great influence in autoimmunity through Toll-like receptors. TLR-7 recognizing single-strand RNA has been involved in SLE. Its activation induces intracellular signal with attraction of MyD88 and NF-kBp65, leading to IFN-α synthesis which correlate with disease activity.

Objective

To assess the expression of TLR-7, MyD88, and NF-kBp65 in B lymphocytes of Mayan women with SLE.

Methods

One hundred patients with SLE and 100 healthy controls, all of them Mayan women, were included. TLR-7 was analyzed on B and T lymphocytes, and MyD88 and NF-kB only in B lymphocytes. Serum INF-α level was evaluated by ELISA.

Results

Significant expression (p < 0.0001) of TLR-7 in B and T lymphocytes and serum IFN-α increased (p = 0.034) was observed in patients. MyD88 and NF-kBp65 were also increased in B lymphocytes of patients. TLR-7 and NF-kBp65 expression correlated, but no correlation with INF-α and disease activity was detected.

Conclusion

Data support the role of TLR-7 and signal proteins in the pathogenesis of SLE in the Mayan population of Yucatán.

Btk inhibition treats TLR7/IFN driven murine lupus

Bruton's tyrosine kinase (Btk) is expressed in a variety of immune cells and previous work has demonstrated that blocking Btk is a promising strategy for treating autoimmune diseases. Herein, we utilized a tool Btk inhibitor, M7583, to determine the therapeutic efficacy of Btk inhibition in two mouse lupus models driven by TLR7 activation and type I interferon. In BXSB-Yaa lupus mice, Btk inhibition reduced autoantibodies, nephritis, and mortality. In the pristane-induced DBA/1 lupus model, Btk inhibition suppressed arthritis, but autoantibodies and the IFN gene signature were not significantly affected; suggesting efficacy was mediated through inhibition of Fc receptors. In vitro studies using primary human macrophages revealed that Btk inhibition can block activation by immune complexes and TLR7 which contributes to tissue damage in SLE. Overall, our results provide translational insight into how Btk inhibition may provide benefit to a variety of SLE patients by affecting both BCR and FcR signaling.

A Phase II study of the efficacy and safety of rontalizumab (rhuMAb interferon-α) in patients with systemic lupus erythematosus (ROSE)

OBJECTIVES

To examine the safety and efficacy of rontalizumab, a humanised IgG1 anti-interferon α (anti-IFN-α) monoclonal antibody, in patients with moderate-to-severe systemic lupus erythematosus (SLE).

METHODS

Patients with active SLE were randomised (2:1) to 750 mg intravenous rontalizumab every 4 weeks or placebo (Part 1), and 300 mg subcutaneous rontalizumab every 2 weeks or placebo (Part 2).

BACKGROUND

Hydroxychloroquine and corticosteroids were allowed. Patients taking immunosuppressants at baseline were required per protocol to discontinue. Efficacy end points included reduction in disease activity by British Isles Lupus Disease Activity Group (BILAG)-2004 (primary), and SLE response index (SRI, secondary) at Week 24. Efficacy was also examined by an exploratory measure of IFN-regulated gene expression (interferon signature metric, ISM).

RESULTS

Patients (n=238) received rontalizumab (n=159) or placebo (n=79). At baseline, the mean Safety of Estrogens in Lupus Erythematosus National Assessment version of the SLE Disease Activity Index (SELENA-SLEDAI) score in all cohorts was ~10, and 75.6% of patients had a high ISM (ISM-High). Efficacy response rates by BILAG and SRI were similar between rontalizumab and placebo groups. However, in the exploratory subgroup of ISM-Low patients, SRI response was higher and steroid use was lower in the rontalizumab-treated patients. There was also a reduction in SELENA-SLEDAI flare index rates (HR 0.61, 0.46 to 0.81, p=0.004) in this subgroup. Adverse events were similar between placebo and rontalizumab groups.

CONCLUSIONS

The primary and secondary end points of this trial were not met in all patients or in patients with high ISM scores. In an exploratory analysis, rontalizumab treatment was associated with improvements in disease activity, reduced flares and decreased steroid use in patients with SLE with low ISM scores.

TRIAL REGISTRATION NUMBER

NCT00962832.

Apoptotic-cell-derived membrane microparticles and IFN-α induce an inflammatory immune response

A dysregulation in the clearance of apoptotic material is considered a major pathogenetic factor for the emergence of autoimmune diseases. Apoptotic-cell-derived membrane microparticles (AdMPs), which are released from the cell surface during apoptosis, have been implicated in the pathogenesis of autoimmunity. Also of importance are cytokines, such as interferon-α (IFN-α), which is known to be a major player in patients with systemic lupus erythematosus (SLE). This study investigates the combined effect of AdMPs and IFN-α on professional phagocytes. In the presence of IFN-α, phagocytosis of AdMPs by human monocytes was significantly increased in a dose-dependent manner. The combination of AdMPs and raised IFN-α concentrations resulted in an increase in the secretion of pro-inflammatory cytokines and an upregulation of surface molecule expression involved in antigen uptake. In addition, macrophage polarisation was shifted towards a more inflammatory type of cell. The synergism between IFN-α and AdMPs seemed to be mediated by an upregulation of phosphorylated STAT1. Our results indicate that IFN-α, together with AdMPs, amplify the initiation and maintenance of inflammation. This mechanism might especially play a crucial role in disorders with a defective clearance of apoptotic material.

Porphyromonas gingivalis RagB is a proinflammatory signal transducer and activator of transcription 4 agonist

Periodontal diseases are semi-ubiquitous and caused by chronic, plaque-induced inflammation. The 55-kDa immunodominant RagB outer membrane protein of Porphyromonas gingivalis, a keystone periodontal pathogen, has been proposed to facilitate nutrient transport. However, potential interactions between RagB and the innate response have not been examined. We determined that RagB exposure led to the differential and dose-related expression of multiple genes encoding proinflammatory mediators [interleukin-1α (IL-1α), IL-1β, IL-6, IL-8 and CCL2; all P < 0.05] in primary human monocytes and to the secretion of tumor necrosis factor and IL-8, but not interferon-γ or IL-12. RagB was shown to be a Toll-like receptor 2 (TLR2) and TLR4 agonist that activated signal transducer and activator of transcription 4 and nuclear factor-κB signaling, as determined by a combination of blocking antibodies, pharmaceutical inhibitors and gene silencing. In keeping, a ΔragB mutant similarly exhibited reduced inflammatory capacity, which was rescued by ragB complementation. These results suggest that RagB elicits a major pro-inflammatory response in primary human monocytes and, therefore, could play an important role in the etiology of periodontitis and systemic sequelae.