Type I interferon in organ-targeted autoimmune and inflammatory diseases

Siglec-1, an easy and contributory inflammation marker in rheumatology

Objectives

Inflammatory markers such as erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are poorly informative about interferon (IFN)-related disorders. In these conditions, the measure of the interferon score (IS), obtained by measuring the expression of IFN-stimulated genes, has been proposed. Flow cytometry-based assays measuring sialic-acid-binding Ig-like lectin 1 (Siglec-1) expression could be a more practical tool for evaluating IFN-inflammation. The study compared Siglec-1 measures with IS and other inflammatory indexes. We compared Siglec-1 measures with IS and other inflammatory indexes in real-world paediatric rheumatology experience.

Methods

We recruited patients with immuno-rheumatological conditions, acute infectious illness and patients undergoing orthopaedic surgery as controls. Siglec-1 expression was measured in all samples, and IS, ESR and CRP were also recorded if available.

Results

Overall, 98 subjects were enrolled in the study, with a total of 104 measures of Siglec-1. Compared with IS, Siglec-1 expression showed good accuracy (86.0%), specificity (72.7%) and sensitivity (85.7%). The measure of the percentage of Siglec-1-positive cells performed best at low levels of IFN-inflammation, while the measure of mean fluorescence intensity performed best at higher levels. Ex vivo studies on IFN-stimulated monocytes confirmed this behaviour. There was no link between Siglec-1 expression and either ESR or CRP, and positive Siglec-1 results were found even when ESR and CRP were normal. A high Siglec-1 expression was also recorded in subjects with acute infections.

Conclusion

Siglec-1 measurement by flow cytometry is an easy tool to detect IFN-related inflammation, even in subjects with normal results of common inflammation indexes.

Targeting pathogenic fibroblast-like synoviocyte subsets in rheumatoid arthritis

Fibroblast-like synoviocytes (FLSs) play a central role in RA pathogenesis and are the main cellular component in the inflamed synovium of patients with rheumatoid arthritis (RA). FLSs are emerging as promising new therapeutic targets in RA. However, fibroblasts perform many essential functions that are required for sustaining tissue homeostasis. Direct targeting of general fibroblast markers on FLSs is challenging because fibroblasts in other tissues might be altered and side effects such as reduced wound healing or fibrosis can occur. To date, no FLS-specific targeted therapies have been applied in the clinical management of RA. With the help of high-throughput technologies such as scRNA-seq in recent years, several specific pathogenic FLS subsets in RA have been identified. Understanding the characteristics of these pathogenic FLS clusters and the mechanisms that drive their differentiation can provide new insights into the development of novel FLS-targeting strategies for RA. Here, we discuss the pathogenic FLS subsets in RA that have been elucidated in recent years and potential strategies for targeting pathogenic FLSs.

A novel subpopulation of monocytes with a strong interferon signature indicated by SIGLEC-1 is present in patients with in recent-onset type 1 diabetes

AIMS/HYPOTHESIS

Type 1 diabetes is a T cell-mediated autoimmune disease characterised by pancreatic beta cell destruction. In this study, we explored the pathogenic immune responses in initiation of type 1 diabetes and new immunological targets for type 1 diabetes prevention and treatment.

METHODS

We obtained peripheral blood samples from four individuals with newly diagnosed latent autoimmune diabetes in adults (LADA) and from four healthy control participants. Single-cell RNA-sequencing (scRNA-seq) was performed on peripheral blood mononuclear cells to uncover transcriptomic profiles of early LADA. Validation was performed through flow cytometry in a cohort comprising 54 LADA, 17 adult-onset type 2 diabetes, and 26 healthy adults, matched using propensity score matching (PSM) based on age and sex. A similar PSM method matched 15 paediatric type 1 diabetes patients with 15 healthy children. Further flow cytometry analysis was performed in both peripheral blood and pancreatic tissues of non-obese diabetic (NOD) mice. Additionally, cell adoptive transfer and clearance assays were performed in NOD mice to explore the role of this monocyte subset in islet inflammation and onset of type 1 diabetes.

RESULTS

The scRNA-seq data showed that upregulated genes in peripheral T cells and monocytes from early-onset LADA patients were primarily enriched in the IFN signalling pathway. A new cluster of classical monocytes (cluster 4) was identified, and the proportion of this cluster was significantly increased in individuals with LADA compared with healthy control individuals (11.93% vs 5.93%, p=0.017) and that exhibited a strong IFN signature marked by SIGLEC-1 (encoding sialoadhesin). These SIGLEC-1+ monocytes expressed high levels of genes encoding C-C chemokine receptors 1 or 2, as well as genes for chemoattractants for T cells and natural killer cells. They also showed relatively low levels of genes for co-stimulatory and HLA molecules. Flow cytometry analysis verified the elevated levels of SIGLEC-1+ monocytes in the peripheral blood of participants with LADA and paediatric type 1 diabetes compared with healthy control participants and those with type 2 diabetes. Interestingly, the proportion of SIGLEC-1+ monocytes positively correlated with disease activity and negatively with disease duration in the LADA patients. In NOD mice, the proportion of SIGLEC-1+ monocytes in the peripheral blood was highest at the age of 6 weeks (16.88%), while the peak occurred at 12 weeks in pancreatic tissues (23.65%). Adoptive transfer experiments revealed a significant acceleration in diabetes onset in the SIGLEC-1+ group compared with the SIGLEC-1- or saline control group.

CONCLUSIONS/INTERPRETATION

Our study identified a novel group of SIGLEC-1+ monocytes that may serve as an important indicator for early diagnosis, activity assessment and monitoring of therapeutic efficacy in type 1 diabetes, and may also be a novel target for preventing and treating type 1 diabetes.

DATA AVAILABILITY

RNA-seq data have been deposited in the GSA human database ( https://ngdc.cncb.ac.cn/gsa-human/ ) under accession number HRA003649.

Elevated Levels of Interferon-α Act Directly on B Cells to Breach Multiple Tolerance Mechanisms Promoting Autoantibody Production

OBJECTIVE

Elevated levels of serum interferon-α (IFNα) and the disruption of B cell tolerance are central to systemic lupus erythematosus (SLE) immunopathogenesis; however, the relationship between these 2 processes remains unclear. The purpose of this study was to investigate the impact of elevated IFNα levels on B cell tolerance mechanisms in vivo and determine whether any changes observed were due to the direct effect of IFNα on B cells.

METHODS

Two classical mouse models of B cell tolerance were used in conjunction with an adenoviral vector encoding IFNα to mimic the sustained elevations of IFNα seen in SLE. The role of B cell IFNα signaling, T cells, and Myd88 signaling was determined using B cell-specific IFNα receptor-knockout, CD4+ T cell-depleted, or Myd88-knockout mice, respectively. Flow cytometry, enzyme-linked immunosorbent assay, real-time quantitative polymerase chain reaction, and cell cultures were used to study the effects of elevated IFNα on the immunologic phenotype.

RESULTS

Elevation of serum IFNα disrupts multiple B cell tolerance mechanisms and leads to autoantibody production. This disruption was dependent upon B cell expression of IFNα receptor. Many of the IFNα-mediated alterations also required the presence of CD4+ T cells as well as Myd88, suggesting that IFNα acts directly on B cells to modify their response to Myd88 signaling and their ability to interact with T cells.

CONCLUSION

The results provide evidence that elevated IFNα levels act directly on B cells to facilitate autoantibody production and further highlight the importance of IFN signaling as a potential therapeutic target in SLE.

Magnetic Relaxation Switching Assay Using IFNα-2b-Conjugated Superparamagnetic Nanoparticles for Anti-Interferon Antibody Detection

Type I interferons, particularly IFNα-2b, play essential roles in eliciting adaptive and innate immune responses, being implicated in the pathogenesis of various diseases, including cancer, and autoimmune and infectious diseases. Therefore, the development of a highly sensitive platform for analysis of either IFNα-2b or anti-IFNα-2b antibodies is of high importance to improve the diagnosis of various pathologies associated with the IFNα-2b disbalance. For evaluation of the anti-IFNα-2b antibody level, we have synthesized superparamagnetic iron oxide nanoparticles (SPIONs) coupled with the recombinant human IFNα-2b protein (SPIONs@IFNα-2b). Employing a magnetic relaxation switching assay (MRSw)-based nanosensor, we detected picomolar concentrations (0.36 pg/mL) of anti-INFα-2b antibodies. The high sensitivity of the real-time antibodies' detection was ensured by the specificity of immune responses and the maintenance of resonance conditions for water spins by choosing a high-frequency filling of short radio-frequency pulses of the generator. The formation of a complex of the SPIONs@IFNα-2b nanoparticles with the anti-INFα-2b antibodies led to a cascade process of the formation of nanoparticle clusters, which was further enhanced by exposure to a strong (7.1 T) homogenous magnetic field. Obtained magnetic conjugates exhibited high negative MR contrast-enhancing properties (as shown by NMR studies) that were also preserved when particles were administered in vivo. Thus, we observed a 1.2-fold decrease of the T2 relaxation time in the liver following administration of magnetic conjugates as compared to the control. In conclusion, the developed MRSw assay based on SPIONs@IFNα-2b nanoparticles represents an alternative immunological probe for the estimation of anti-IFNα-2b antibodies that could be further employed in clinical studies.

2022 EULAR points to consider for the measurement, reporting and application of IFN-I pathway activation assays in clinical research and practice

BACKGROUND

Type I interferons (IFN-Is) play a role in a broad range of rheumatic and musculoskeletal diseases (RMDs), and compelling evidence suggests that their measurement could have clinical value, although testing has not progressed into clinical settings.

OBJECTIVE

To develop evidence-based points to consider (PtC) for the measurement and reporting of IFN-I assays in clinical research and to determine their potential clinical utility.

METHODS

EULAR standardised operating procedures were followed. A task force including rheumatologists, immunologists, translational scientists and a patient partner was formed. Two systematic reviews were conducted to address methodological and clinical questions. PtC were formulated based on the retrieved evidence and expert opinion. Level of evidence and agreement was determined.

RESULTS

Two overarching principles and 11 PtC were defined. The first set (PtC 1-4) concerned terminology, assay characteristics and reporting practices to enable more consistent reporting and facilitate translation and collaborations. The second set (PtC 5-11) addressed clinical applications for diagnosis and outcome assessments, including disease activity, prognosis and prediction of treatment response. The mean level of agreement was generally high, mainly in the first PtC set and for clinical applications in systemic lupus erythematosus. Harmonisation of assay methodology and clinical validation were key points for the research agenda.

CONCLUSIONS

IFN-I assays have a high potential for implementation in the clinical management of RMDs. Uptake of these PtC will facilitate the progress of IFN-I assays into clinical practice and may be also of interest beyond rheumatology.

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.

The expression of zinc finger 804a (ZNF804a) and cyclin-dependent kinase 1 (CDK1) genes is related to the pathogenesis of rheumatoid arthritis

CONTEXT

ZNF804a and CDK1 genes code for proteins involved in inflammatory pathways.

OBJECTIVE

This study aimed to investigate the correlation of ZNF804a and CDK1 expression profiles in RA with the activity and the severity of the disease and to assess their association with inflammatory reactions in the Egyptian RA patients.

METHODS

ZNF804a and CDK1 expression profiles were assessed using quantitative PCR (qRT-PCR). Clinical and laboratory parameters were evaluated.

RESULTS

ZNF804a expression was down-regulated by 0.177-fold while CDK1 expression was up-regulated to 3.29-fold in RA patients compared with healthy controls (p < .001). ZNF804a down-regulation was negatively correlated with CRP, RF, disease activity score of 28 joints (DAS) using CRP (DAS-CRP) and TNF-α. CDK1 overexpression was correlated with IFN-1 and ACPA in RA patients.

CONCLUSION

ZNF804a and CDK1 genes are implicated in RA pathogenesis due to their influences on TNF-α and IFN-1 which contribute to inflammation in RA patients.

FAM46C as a Potential Marker for Pan-Cancer Prognosis and Predicting Immunotherapeutic Efficacy

Background:FAM46C is a common mutated gene in tumours. A comprehensive understanding of the relationship between FAM46C expression and pan-cancer can guide clinical prognosis and broaden the immunotherapeutic targets.

Methods: Data from The Cancer Genome Atlas and Genotype-Tissue Expression (GTEx) databases were obtained, and gene expression of different tumour types and stages was analysed. Immunohistochemical analysis was performed to detect differences in the FAM46C protein levels in normal and cancerous tissues. The genetic variation of FAM46C was characterised using cBioPortal. The clinical prognostic value of FAM46C and the impact of FAM46C expression levels on the prognosis of patients with different types of cancer were assessed based on Kaplan–Meier and Cox regression analyses. Gene set enrichment analysis (GSEA) was used to analyse the pathways associated with FAM46C. Correlations between FAM46C expression levels and immune infiltration were assessed using the TIMER2 database and CIBERSORT algorithm, and correlations between FAM46C expression and the ESTIMATE, immune and stromal scores were analysed using the ESTIMATE algorithm. In addition, we also analysed the correlation between FAM46C expression and immune activation, suppression genes and immune chemokines.

Results: The expression level of FAM46C was correlated with the prognosis of most tumours, and low expression levels often suggested a poor prognosis. FAM46C was positively correlated with the abundance of CD4+ T cells, CD8+ T cells and plasma B lymphocytes in the tumour microenvironment. FAM46C exhibited a strong correlation with immunomodulatory pathways, immunomodulatory factors and immune markers. In addition, high FAM46C expression correlated with tumour mutational burden in acute myeloid leukaemia and microsatellite instability in endometrial cancer.

Conclusion: Our study suggests that FAM46C can be a potential prognostic marker for pan-cancer, is closely associated with immune regulation and may be an immune checkpoint to guide future clinical immunotherapy.

Herbal extracts that induce type I interferons through Toll-like receptor 4 signaling

Background

A mixture of five herbal extracts called internatural (INT), which is prepared from pumpkin seeds, purple turmeric, pearl barley, corn pistil, and cinnamon, is widely used by people in Japan and elsewhere for its immunity-enhancing effects and general health. Although anecdotal evidence indicates its efficacy, the mechanisms by which INT boosts immunity have remained unknown.

Objective

The aim of this study was to investigate whether INT induces type I interferons (IFNs) in murine bone marrow-derived macrophages (BMDMs) and by what mechanism.

Design

We measured induction of type I IFNs (IFNβ and IFNα) in BMDMs treated with INT or other Toll-like receptor ligands: bacterial lipopolysaccharides (LPS), dsRNA, poly(I:C), and CpG oligonucleotides. To investigate whether INT signals through Toll-like receptor 4 (TLR4), we tested TLR4-specific inhibitor. We also tested if INT utilizes TLR4 adaptors, toll/IL-1 receptor (TIR) domain-containing adaptor (TRIF), or myeloid differentiation factor 88 (MyD88), we examined INT induction of IFNβ in TRIF-KO and MyD88-KO BMDMs. We then investigated whether INT provides an antiviral effect upon fibroblasts either directly or indirectly using the encephalomyocarditis virus (EMCV) model.

Results

We first observed that INT, when added to BMDMs, potently induces type I IFNs (IFNβ and IFNα) within 2 h. INT induction of IFN expression was mediated by TLR4, which signaled through the TRIF/MyD88 adaptors, similar to LPS. A high-molecular-weight fraction (MW > 10,000) of INT extracts contained IFN-inducing activity. Supernatants from INT-treated BMDMs protected untreated fibroblast from EMCV infection as reduced viral titers.

Conclusions

INT induced type I IFN mRNA and proteins in BMDMs and other cell types. This induction was mediated by TLR4, which transduces signals using the TRIF/MyD88 pathway. The high-MW component of INT contained type I IFN inducing activity. The supernatants from INT-treated cells displayed antiviral activity and protected cells from EMCV infection. These findings indicate that INT is a novel natural IFN inducer that strengthens host’s innate immunity.

Differential serum interferon-β levels in autoimmune thyroid diseases

INTRODUCTION

Interferon (IFN)-β is known as an environmental trigger for the occurrence of autoimmune thyroid disease (AITD). However, the association of another type-1 IFN, IFN-β, with AITD is unknown.

MATERIAL AND METHODS

In the study, we explored the association of serum IFN-β levels with AITD in an ethnic Chinese (i.e., Taiwanese) population. We enrolled 160 patients with Graves' disease (GD), 47 patients with Hashimoto's thyroiditis (HT), and 119 healthy controls. Serum IFN-β and B-cell activating factor (BAFF) levels were quantified in healthy controls at the baseline and in patients with AITD either prior to receiving medication or while under medication. Thyroid function and thyroid-stimulating hormone receptor antibody (TSHRAb) levels were measured at the time of serum collection.

RESULTS

Serum IFN-β levels were lower in the HT group than in the control group (p = 0.031). A significant inverse correlation was observed between IFN-β and TSHRAb levels in men with GD (r = -0.433, p = 0.044). Serum IFN-β levels were also negatively associated with BAFF levels in men with GD, HT, and AITD (r = -0.320, p = 0.032; r = -0.817, p = 0.047; and r = -0.354, p = 0.011, respectively), but not in women with GD, HT, or AITD.

CONCLUSIONS

Serum IFN-β levels were lower in HT patients. Correlations of serum IFN-β with TSHRAb and BAFF levels were found to be gender-specific. Further well-designed studies with larger sample sizes are required to confirm our findings.

Immune regulator LGP2 targets Ubc13/UBE2N to mediate widespread interference with K63 polyubiquitination and NF-κB activation

Lysine 63-linked polyubiquitin (K63-Ub) chains activate a range of cellular immune and inflammatory signaling pathways, including the mammalian antiviral response. Interferon and antiviral genes are triggered by TRAF family ubiquitin ligases that form K63-Ub chains. LGP2 is a feedback inhibitor of TRAF-mediated K63-Ub that can interfere with diverse immune signaling pathways. Our results demonstrate that LGP2 inhibits K63-Ub by association with and sequestration of the K63-Ub-conjugating enzyme, Ubc13/UBE2N. The LGP2 helicase subdomain, Hel2i, mediates protein interaction that engages and inhibits Ubc13/UBE2N, affecting control over a range of K63-Ub ligase proteins, including TRAF6, TRIM25, and RNF125, all of which are inactivated by LGP2. These findings establish a unifying mechanism for LGP2-mediated negative regulation that can modulate a variety of K63-Ub signaling pathways.

TNF leads to mtDNA release and cGAS/STING-dependent interferon responses that support inflammatory arthritis

Tumor necrosis factor (TNF) is a key driver of several inflammatory diseases, such as rheumatoid arthritis, inflammatory bowel disease, and psoriasis, in which affected tissues show an interferon-stimulated gene signature. Here, we demonstrate that TNF triggers a type-I interferon response that is dependent on the cyclic guanosine monophosphate-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway. We show that TNF inhibits PINK1-mediated mitophagy and leads to altered mitochondrial function and to an increase in cytosolic mtDNA levels. Using cGAS-chromatin immunoprecipitation (ChIP), we demonstrate that cytosolic mtDNA binds to cGAS after TNF treatment. Furthermore, TNF induces a cGAS-STING-dependent transcriptional response that mimics that of macrophages from rheumatoid arthritis patients. Finally, in an inflammatory arthritis mouse model, cGAS deficiency blocked interferon responses and reduced inflammatory cell infiltration and joint swelling. These findings elucidate a molecular mechanism linking TNF to type-I interferon signaling and suggest a potential benefit for therapeutic targeting of cGAS/STING in TNF-driven diseases.

Interferon Genes Are Influenced by 17β-Estradiol in SLE

Recent evidence suggests the existence of a nexus between inflammatory pathways and the female sex hormone 17β-estradiol, resulting in increased interferon-stimulated genes (ISGs), autoantibodies, and dysregulation of immune cells in SLE. However, the molecular mechanisms and the effect of estradiol on candidate target genes and their pathways remains poorly understood. Our previous work suggests that female SLE patients have increased estradiol levels compared to healthy controls. In the present study, we explored the effects of 17β-estradiol treatment on expression of IFN (interferons)-stimulated genes and pro-inflammatory cytokines/chemokines. We found significantly increased (5-10-fold) expression of IFN-regulated genes in healthy females. Furthermore, we found significantly increased plasma levels of IL-6, IL-12, IL-17, IL-18, stem cell factor (SCF), and IL-21/IL-23 in SLE patients compared to healthy controls, and those levels positively correlated with the plasma levels of 17β-estradiol. In addition, levels of IL-21 positively correlated with the SLE disease activity index (SLEDAI) score of SLE patients. In vitro treatment of PBMCs from either SLE patients or healthy controls with 17β-estradiol at physiological concentration (~50 pg/ml) also significantly increased secretion of many pro-inflammatory cytokines and chemokines (IL-6, IL-12, IL-17, IL-8, IFN-γ; MIP1α, and MIP1β) in both groups. Further our data revealed that 17β-estradiol significantly increased the percentage of CD3⁺CD69⁺ and CD3⁺IFNγ⁺ T cells; whereas, simultaneous addition of 17β-estradiol and an ERα inhibitor prevented this effect. Collectively, our findings indicate that 17β-estradiol participates in the induction of pro-inflammatory cytokines and chemokines and further influences interferon genes and pathways.

Resilience in Long-Term Viral Infection: Genetic Determinants and Interactions

Virus-induced neurological sequelae resulting from infection by Theiler's murine encephalomyelitis virus (TMEV) are used for studying human conditions ranging from epileptic seizures to demyelinating disease. Mouse strains are typically considered susceptible or resistant to TMEV infection based on viral persistence and extreme phenotypes, such as demyelination. We have identified a broader spectrum of phenotypic outcomes by infecting strains of the genetically diverse Collaborative Cross (CC) mouse resource. We evaluated the chronic-infection gene expression profiles of hippocampi and thoracic spinal cords for 19 CC strains in relation to phenotypic severity and TMEV persistence. Strains were clustered based on similar phenotypic profiles and TMEV levels at 90 days post-infection, and we categorized distinct TMEV response profiles. The three most common profiles included "resistant" and "susceptible," as before, as well as a "resilient" TMEV response group which experienced both TMEV persistence and mild neurological phenotypes even at 90 days post-infection. Each profile had a distinct gene expression signature, allowing the identification of pathways and networks specific to each TMEV response group. CC founder haplotypes for genes involved in these pathways/networks revealed candidate response-specific alleles. These alleles demonstrated pleiotropy and epigenetic (miRNA) regulation in long-term TMEV infection, with particular relevance for resilient mouse strains.

The Pathogenesis, Molecular Mechanisms, and Therapeutic Potential of the Interferon Pathway in Systemic Lupus Erythematosus and Other Autoimmune Diseases

Therapeutic success in treating patients with systemic lupus erythematosus (SLE) is limited by the multivariate disease etiology, multi-organ presentation, systemic involvement, and complex immunopathogenesis. Agents targeting B-cell differentiation and survival are not efficacious for all patients, indicating a need to target other inflammatory mediators. One such target is the type I interferon pathway. Type I interferons upregulate interferon gene signatures and mediate critical antiviral responses. Dysregulated type I interferon signaling is detectable in many patients with SLE and other autoimmune diseases, and the extent of this dysregulation is associated with disease severity, making type I interferons therapeutically tangible targets. The recent approval of the type I interferon-blocking antibody, anifrolumab, by the US Food and Drug Administration for the treatment of patients with SLE demonstrates the value of targeting this pathway. Nevertheless, the interferon pathway has pleiotropic biology, with multiple cellular targets and signaling components that are incompletely understood. Deconvoluting the complexity of the type I interferon pathway and its intersection with lupus disease pathology will be valuable for further development of targeted SLE therapeutics. This review summarizes the immune mediators of the interferon pathway, its association with disease pathogenesis, and therapeutic modalities targeting the dysregulated interferon pathway.

Dendritic Cell-Mediated Regulation of Liver Ischemia-Reperfusion Injury and Liver Transplant Rejection

Liver allograft recipients are more likely to develop transplantation tolerance than those that receive other types of organ graft. Experimental studies suggest that immune cells and other non-parenchymal cells in the unique liver microenvironment play critical roles in promoting liver tolerogenicity. Of these, liver interstitial dendritic cells (DCs) are heterogeneous, innate immune cells that appear to play pivotal roles in the instigation, integration and regulation of inflammatory responses after liver transplantation. Interstitial liver DCs (recruited in situ or derived from circulating precursors) have been implicated in regulation of both ischemia/reperfusion injury (IRI) and anti-donor immunity. Thus, livers transplanted from mice constitutively lacking DCs into syngeneic, wild-type recipients, display increased tissue injury, indicating a protective role of liver-resident donor DCs against transplant IRI. Also, donor DC depletion before transplant prevents mouse spontaneous liver allograft tolerance across major histocompatibility complex (MHC) barriers. On the other hand, mouse liver graft-infiltrating host DCs that acquire donor MHC antigen via "cross-dressing", regulate anti-donor T cell reactivity in association with exhaustion of graft-infiltrating T cells and promote allograft tolerance. In an early phase clinical trial, infusion of donor-derived regulatory DCs (DCreg) before living donor liver transplantation can induce alterations in host T cell populations that may be conducive to attenuation of anti-donor immune reactivity. We discuss the role of DCs in regulation of warm and liver transplant IRI and the induction of liver allograft tolerance. We also address design of cell therapies using DCreg to reduce the immunosuppressive drug burden and promote clinical liver allograft tolerance.

Effects of Peptide-Induced Immune Tolerance on Murine Lupus

The regulation of autoimmunity and the molecular mechanisms by which different immune cells, including T cells, polymorphonuclear leukocytes (PMN-granulocytes), and B cells suppress autoimmune diseases is complex. We have shown previously that BWF1 lupus mice are protected from autoimmunity after i.v. injection or oral administration of tolerogenic doses of pCons, an artificial synthetic peptide based on sequences containing MHC class I and MHC class II determinants in the VH region of a J558-encoded BWF1 anti-DNA Ab. Several T cell subsets can transfer this tolerance. In this study, we determined the potential roles of granulocytes, B cells and regulatory T cells altered by pCons treatment in the BWF1 (NZB/NZW) mouse model of lupus. Immunophenotyping studies indicated that pCons treatment of BWF1 mice significantly increased CD4⁺FoxP3⁺ T cells, reduced the percent of B cells expressing CD19⁺CD5⁺ but increased the percent of CD19⁺CD1d⁺ regulatory B cells and increased the ability of the whole B cell population to suppress IgG anti-DNA production in vitro. pCons treatment significantly decreased the expression of CTLA-4 (cytotoxic T-lymphocyte-associated protein-4) in CD8⁺ T cells. In addition, peptide administration modified granulocytes so they became suppressive. We co-cultured sorted naïve B cells from mice making anti-DNA Ab (supported by addition of sorted naive CD4⁺ and CD8⁺ T cells from young auto-antibody-negative BWF1 mice) with sorted B cells or granulocytes from tolerized mice. Both tolerized granulocytes and tolerized B cells significantly suppressed the production of anti-DNA in vitro. In granulocytes from tolerized mice compared to saline-treated littermate controls, real-time PCR analysis indicated that expression of interferon-induced TNFAIP2 increased more than 2-fold while Ptdss2 and GATA1 mRNA were up-regulated more than 10-fold. In contrast, expression of these genes was significantly down-regulated in tolerized B cells. Further, another IFN-induced protein, Bcl2, was reduced in tolerized B cells as determined by Western blot analyses. In contrast, expression of FoxP3 was significantly increased in tolerized B cells. Together, these data suggest that B cells and granulocytes are altered toward suppressive functions by in vivo tolerization of BWF1 mice with pCons and it is possible these cell types participate in the clinical benefits seen in vivo.

Mitochondrial protein CMPK2 regulates IFN alpha-enhanced foam cell formation, potentially contributing to premature atherosclerosis in SLE

Background

Premature atherosclerosis occurs in patients with SLE; however, the mechanisms remain unclear. Both mitochondrial machinery and proinflammatory cytokine interferon alpha (IFN-α) potentially contribute to atherogenic processes in SLE. Here, we explore the roles of the mitochondrial protein cytidine/uridine monophosphate kinase 2 (CMPK2) in IFN-α-mediated pro-atherogenic events.

Methods

Foam cell measurements were performed by oil red O staining, Dil-oxLDL uptake and the BODIPY approach. The mRNA and protein levels were measured by qPCR and Western blotting, respectively. Isolation of CD4+ T cells and monocytes was performed with monoclonal antibodies conjugated with microbeads. Manipulation of protein expression was conducted by either small interference RNA (siRNA) knockdown or CRISPR/Cas9 knockout. The expression of mitochondrial reactive oxygen species (mtROS) was determined by flow cytometry and confocal microscopy.

Results

IFN-α enhanced oxLDL-induced foam cell formation and Dil-oxLDL uptake by macrophages. In addition to IFN-α, several triggers of atherosclerosis, including thrombin and IFN-γ, can induce CMPK2 expression, which was elevated in CD4+ T cells and CD14+ monocytes isolated from SLE patients compared to those isolated from controls. The analysis of cellular subfractions revealed that CMPK2 was present in both mitochondrial and cytosolic fractions. IFN-α-induced CMPK2 expression was inhibited by Janus kinase (JAK)1/2 and tyrosine kinase 2 (Tyk2) inhibitors. Both the knockdown and knockout of CMPK2 attenuated IFN-α-mediated foam cell formation, which involved the reduction of scavenger receptor class A (SR-A) expression. CMPK2 also regulated IFN-α-enhanced mtROS production and inflammasome activation.

Conclusions

The study suggests that CMPK2 plays contributing roles in the pro-atherogenic effects of IFN-α.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13075-021-02470-6.

JAK selectivity and the implications for clinical inhibition of pharmacodynamic cytokine signalling by filgotinib, upadacitinib, tofacitinib and baricitinib

Objective

Janus kinase inhibitors (JAKinibs) are efficacious in rheumatoid arthritis (RA) with variable reported rates of adverse events, potentially related to differential JAK family member selectivity. Filgotinib was compared with baricitinib, tofacitinib and upadacitinib to elucidate the pharmacological basis underlying its clinical efficacy and safety.

Methods

In vitro JAKinib inhibition of signal transducer and activator of transcription phosphorylation (pSTAT) was measured by flow cytometry in peripheral blood mononuclear cells and whole blood from healthy donors and patients with RA following cytokine stimulation of distinct JAK/STAT pathways. The average daily pSTAT and time above 50% inhibition were calculated at clinical plasma drug exposures in immune cells. The translation of these measures was evaluated in ex vivo-stimulated assays in phase 1 healthy volunteers.

Results

JAKinib potencies depended on cytokine stimulus, pSTAT readout and cell type. JAK1-dependent pathways (interferon (IFN)α/pSTAT5, interleukin (IL)-6/pSTAT1) were among the most potently inhibited by all JAKinibs in healthy and RA blood, with filgotinib exhibiting the greatest selectivity for JAK1 pathways. Filgotinib (200 mg once daily) had calculated average daily target inhibition for IFNα/pSTAT5 and IL-6/pSTAT1 that was equivalent to tofacitinib (5 mg two times per day), upadacitinib (15 mg once daily) and baricitinib (4 mg once daily), with the least average daily inhibition for the JAK2-dependent and JAK3-dependent pathways including IL-2, IL-15, IL-4 (JAK1/JAK3), IFNγ (JAK1/JAK2), granulocyte colony stimulating factor, IL-12, IL-23 (JAK2/tyrosine kinase 2) and granulocyte-macrophage colony-stimulating factor (JAK2/JAK2). Ex vivo pharmacodynamic data from phase 1 healthy volunteers clinically confirmed JAK1 selectivity of filgotinib.

Conclusion

Filgotinib inhibited JAK1-mediated signalling similarly to other JAKinibs, but with less inhibition of JAK2-dependent and JAK3-dependent pathways, providing a mechanistic rationale for its apparently differentiated efficacy:safety profile.

Diminished cytokine-induced Jak/STAT signaling is associated with rheumatoid arthritis and disease activity

Rheumatoid arthritis (RA) is a systemic and incurable autoimmune disease characterized by chronic inflammation in synovial lining of joints. To identify the signaling pathways involved in RA, its disease activity, and treatment response, we adapted a systems immunology approach to simultaneously quantify 42 signaling nodes in 21 immune cell subsets (e.g., IFNα→p-STAT5 in B cells) in peripheral blood mononuclear cells (PBMC) from 194 patients with longstanding RA (including 98 patients before and after treatment), and 41 healthy controls (HC). We found multiple differences between patients with RA compared to HC, predominantly in cytokine-induced Jak/STAT signaling in many immune cell subsets, suggesting pathways that may be associated with susceptibility to RA. We also found that high RA disease activity, compared to low disease activity, was associated with decreased (e.g., IFNα→p-STAT5, IL-10→p-STAT1) or increased (e.g., IL-6→STAT3) response to stimuli in multiple cell subsets. Finally, we compared signaling in patients with established, refractory RA before and six months after initiation of methotrexate (MTX) or TNF inhibitors (TNFi). We noted significant changes from pre-treatment to post-treatment in IFNα→p-STAT5 signaling and IL-10→p-STAT1 signaling in multiple cell subsets; these changes brought the aberrant RA signaling profiles toward those of HC. This large, comprehensive functional signaling pathway study provides novel insights into the pathogenesis of RA and shows the potential of quantification of cytokine-induced signaling as a biomarker of disease activity or treatment response.

RNA helicase DDX5 suppresses IFN-I antiviral innate immune response by interacting with PP2A-Cβ to deactivate IRF3

DEAD-box (DDX) helicases are critical for recognizing viral nucleic acids to regulate antiviral innate immunity. Although DDX5 has been reported to participate in various virus infection, whether DDX5 regulates innate immune responses and its underlying mechanisms are still unknown. Here, we report that DDX5 is a negative regulator of type I IFN (IFN-I) production in antiviral responses. DDX5 knockdown significantly promoted DNA or RNA virus infection-induced IFN-I production and IFN-stimulated genes (ISGs) expression, while ectopic expression of DDX5 inhibited IFN-I production and promoted viral replication. Furthermore, we found that DDX5 specifically interacted with serine/threonine-protein phosphatase 2 A catalytic subunit beta (PP2A-Cβ) and viral infection enhanced the interaction between DDX5 and PP2A-Cβ. Besides, PP2A-Cβ interacted with IFN regulatory factor 3 (IRF3), and PP2A-Cβ knockdown promoted viral infection-induced IRF3 phosphorylation and IFN-I production. In addition, DDX5 knockdown rendered the mice more resistant to viral infection and enhanced antiviral innate immunity in vivo. Thus, DDX5 suppresses IFN-I antiviral innate immune response by interacting with PP2A-Cβ to deactivate IRF3. Together, these findings identify a negative role of DDX5 on regulating IFN-I signaling in innate immune responses.

NF-κB signaling in rheumatoid arthritis with focus on fibroblast-like synoviocytes

The nuclear factor-κB (NF-κB) signaling pathway regulates multiple processes in innate and adaptive immune cells. This pathway is involved in inflammation through the regulation of cytokines, chemokines, and adhesion molecules expression. The NF-κB transcription factor also participates in the survival, proliferation, and differentiation of cells. Therefore, deregulated NF-κB activation contributes to the pathogenesis of inflammatory diseases. Rheumatoid arthritis (RA) is classified as a heterogeneous and complex autoimmune inflammatory disease. Although different immune and non-immune cells contribute to the RA pathogenesis, fibroblast-like synoviocytes (FLSs) play a crucial role in disease progression. These cells are altered during the disease and produce inflammatory mediators, including inflammatory cytokines and matrix metalloproteinases, which result in joint and cartilage erosion. Among different cell signaling pathways, it seems that deregulated NF-κB activation is associated with the inflammatory picture of RA. NF-κB activation can also promote the proliferation of RA-FLSs as well as the inhibition of FLS apoptosis that results in hyperplasia in RA synovium. In this review, the role of NF-κB transcription factor in immune and non-immune cells (especially FLSs) that are involved in RA pathogenesis are discussed.

Mebendazole is unique among tubulin-active drugs in activating the MEK-ERK pathway

We recently showed that the anti-helminthic compound mebendazole (MBZ) has immunomodulating activity in monocyte/macrophage models and induces ERK signalling. In the present study we investigated whether MBZ induced ERK activation is shared by other tubulin binding agents (TBAs) and if it is observable also in other human cell types. Curated gene signatures for a panel of TBAs in the LINCS Connectivity Map (CMap) database showed a unique strong negative correlation of MBZ with MEK/ERK inhibitors indicating ERK activation also in non-haematological cell lines. L1000 gene expression signatures for MBZ treated THP-1 monocytes also connected negatively to MEK inhibitors. MEK/ERK phosphoprotein activity testing of a number of TBAs showed that only MBZ increased the activity in both THP-1 monocytes and PMA differentiated macrophages. Distal effects on ERK phosphorylation of the substrate P90RSK and release of IL1B followed the same pattern. The effect of MBZ on MEK/ERK phosphorylation was inhibited by RAF/MEK/ERK inhibitors in THP-1 models, CD3/IL2 stimulated PBMCs and a MAPK reporter HEK-293 cell line. MBZ was also shown to increase ERK activity in CD4+ T-cells from lupus patients with known defective ERK signalling. Given these mechanistic features MBZ is suggested suitable for treatment of diseases characterized by defective ERK signalling, notably difficult to treat autoimmune diseases.

FAM46C inhibits cell proliferation and cell cycle progression and promotes apoptosis through PTEN/AKT signaling pathway and is associated with chemosensitivity in prostate cancer

Family with sequence similarity 46 member C (FAM46C) is a non-canonical poly(A) polymerase that is associated with tumorigenesis. However, its role in prostate cancer development is not fully understood. Herein, we determined expression pattern of FAM46C in prostate cancer and further identified its effect on the tumorigenesis and chemosensitivity. FAM46C expression was decreased in prostate cancer tissues and cell lines compared with corresponding controls. FAM46C expression was significantly associated with the Gleason score, tumor size and overall survival. FAM46C knockdown in 22RV1 and DU145 cells significantly inhibited apoptosis and promoted cell proliferation and cell cycle progression as well as activation of AKT. FAM46C overexpression had an inverse effect in DU145 cells and inhibited tumor growth in vivo. FAM46C inhibited cell proliferation and cell cycle progression and induced apoptosis via the PTEN/AKT signaling pathway. FAM46C promoted PTEN expression through inhibiting PTEN ubiquitination. The prostate cancer cells and patient-derived xenograft (PDX) mice with high-FAM46C-expressing demonstrated an enhanced chemosensitivity to docetaxel. These findings suggest that FAM46C control cell proliferation, cell cycle and apoptosis through PTEN/AKT signaling pathway and is associated with chemosensitivity of prostate cancer. Modulation of their levels may offer a new approach for improving anti-tumor efficacy for chemotherapeutic agents in prostate cancer.

An Essential Role for Perforin-2 in Type I IFN Signaling

Type I IFNs play a complex role in determining the fate of microbial pathogens and may also be deleterious to the host during bacterial and viral infections. Upon ligand binding, a receptor proximal complex consisting of IFN-α and -β receptors 1 and 2 (IFNAR1, IFNAR2, respectively), tyrosine kinase 2 (Tyk2), Jak1, and STAT2 are assembled and promote the phosphorylation of STAT1 and STAT2. However, how the IFNARs proximal complex is assembled upon binding to IFN is poorly understood. In this study, we show that the membrane-associated pore-forming protein Perforin-2 (P2) is critical for LPS-induced endotoxic shock in wild-type mice. Type I IFN-mediated JAK-STAT signaling is severely impaired, and activation of MAPKs and PI3K signaling pathways are delayed in P2-deficient mouse bone marrow-derived macrophages, mouse embryonic fibroblasts (MEFs), and human HeLa cells upon IFN stimulation. The P2 N-glycosylated extracellular membrane attack complex/perforin domain and the P2 domain independently associate with the extracellular regions of IFNAR1 and IFNAR2, respectively, in resting MEFs. In addition, the P2 cytoplasmic tail domain mediated the constitutive interaction between STAT2 and IFNAR2 in resting MEFs, an interaction that is dependent on the association of the extracellular regions of P2 and IFNAR2. Finally, the constitutive association of P2 with both receptors and STAT2 is critical for the receptor proximal complex assembly and reciprocal transphosphorylation of Jak1 and Tyk2 as well as the phosphorylation and activation of STAT1 and STAT2 upon IFN-β stimulation.

Effects of Treatment with the Hypomethylating Agent 5-aza-2'-deoxycytidine in Murine Type II Collagen-Induced Arthritis

The emerging role of epigenetics in the pathogenesis of autoimmune diseases has recently attracted much interest on the possible use of epigenetic modulators for the prevention and treatment of these diseases. In particular, we and others have shown that drugs that inhibit DNA methylation, such as azacitidine (AZA) and decitabine (DAC), already used for the treatment of acute myeloid leukemia, exert powerful beneficial effects in rodent models of type 1 diabetes, multiple sclerosis, and Guillain Barrè syndrome. Along this line of research, we have presently studied the effects of DAC in a murine model of rheumatoid arthritis induced by type II collagen and have demonstrated that DAC administration was associated with a significant amelioration of the clinical condition, along with in vivo and ex vivo modification of the immunological profile of the so-treated mice, that exhibited a diminished production of Th1 and Th17 pro-inflammatory cytokines and reduction of anti-type II collagen autoantibodies.

Chronic Immune Activation in Systemic Lupus Erythematosus and the Autoimmune PTPN22 Trp620 Risk Allele Drive the Expansion of FOXP3+ Regulatory T Cells and PD-1 Expression

In systemic lupus erythematosus (SLE), perturbed immunoregulation underpins a pathogenic imbalance between regulatory and effector CD4⁺ T-cell activity. However, to date, the characterization of the CD4⁺ regulatory T cell (Treg) compartment in SLE has yielded conflicting results. Here we show that patients have an increased frequency of CD4⁺FOXP3⁺ cells in circulation owing to a specific expansion of thymically-derived FOXP3⁺HELIOS⁺ Tregs with a demethylated FOXP3 Treg-specific demethylated region. We found that the Treg expansion was strongly associated with markers of recent immune activation, including PD-1, plasma concentrations of IL-2 and the type I interferon biomarker soluble SIGLEC-1. Since the expression of the negative T-cell signaling molecule PTPN22 is increased and a marker of poor prognosis in SLE, we tested the influence of its missense risk allele Trp⁶²⁰ (rs2476601C>T) on Treg frequency. Trp⁶²⁰ was reproducibly associated with increased frequencies of thymically-derived Tregs in blood, and increased PD-1 expression on both Tregs and effector T cells (Teffs). Our results support the hypothesis that FOXP3⁺ Tregs are increased in SLE patients as a consequence of a compensatory mechanism in an attempt to regulate pathogenic autoreactive Teff activity. We suggest that restoration of IL-2-mediated homeostatic regulation of FOXP3⁺ Tregs by IL-2 administration could prevent disease flares rather than treating at the height of a disease flare. Moreover, stimulation of PD-1 with specific agonists, perhaps in combination with low-dose IL-2, could be an effective therapeutic strategy in autoimmune disease and in other immune disorders.

RNF144B inhibits LPS-induced inflammatory responses via binding TBK1

Innate immune responses need to be precisely controlled to avoid prolonged inflammation and prevent unwanted damage to the host. Here, we report that RNF144B responded dynamically to LPS stimulation and negatively regulated LPS‐induced inflammation. We found that RNF144B interacted with the scaffold/dimerization domain (SDD) of TANK binding kinase 1 (TBK1) through the in between RING (IBR) domain to inhibit its phosphorylation and K63‐linked polyubiquitination, which led to TBK1 inactivation, IRF3 dephosphorylation, and IFN‐β reduction. RNF144B knockdown with siRNA increased IRF3 activation and IFN‐β production in response to LPS stimulation. Our study identifies that RNF144B interaction with TBK1 is sufficient to inactivate TBK1 and delineates a previously unrecognized role for RNF144B in innate immune responses.

A cell type-specific transcriptomic approach to map B cell and monocyte type I interferon-linked pathogenic signatures in Multiple Sclerosis

Alteration in endogenous Interferon (IFN) system may profoundly impact immune cell function in autoimmune diseases. Here, we provide evidence that dysregulation in IFN-regulated genes and pathways are involved in B cell- and monocyte-driven pathogenic contribution to Multiple Sclerosis (MS) development and maintenance. In particular, by using an Interferome-based cell type-specific approach, we characterized an increased susceptibility to an IFN-linked caspase-3 dependent apoptotic cell death in both B cells and monocytes of MS patients that may arise from their chronic activation and persistent stimulation by activated T cells. Ongoing caspase-3 activation functionally impacts on MS monocyte properties influencing the STAT-3/IL-16 axis, thus, driving increased expression and massive release of the bio-active IL-16 triggering and perpetuating CD4⁺ T cell migration. Importantly, our analysis also identified a previously unknown multi-component defect in type I IFN-mediated signaling and response to virus pathways specific of MS B cells, impacting on induction of anti-viral responses and Epstein-barr virus infection control in patients. Taking advantage of cell type-specific transcriptomics and in-depth functional validation, this study revealed pathogenic contribution of endogenous IFN signaling and IFN-regulated cell processes to MS pathogenesis with implications on fate and functions of B cells and monocytes that may hold therapeutic potential.

Immune response biomarkers in human and veterinary research

Biomarkers are increasingly utilised in biological research and clinical practice for diagnosis of disease, monitoring of therapeutic prognosis, or as end points in clinical studies. Cytokines are small molecules that orchestrate immune responses and as such have great potential as biomarkers for both human and veterinary fields. Given the ease of sampling in the blood, and their high prevalence in clinical applications we will focus on protein detection as an area for biomarker discovery. This is facilitated by new technological developments such as digital ELISA that have led to significant increases in sensitivity. Two highly relevant examples include type I interferons, namely IFNα, that is now directly quantifiable by digital ELISA from biological samples. The application of this approach to the study of the unique bat interferon response may reveal novel findings with applications in both human and veterinary research. As a second example we will describe the use of CXCL10 as a disease biomarker in Tuberculosis, highlighting findings from human and mouse studies that should be considered in veterinary research. In summary, we describe how cytokines may be applied as novel biomarkers and illustrate two key examples where human and veterinary research may complement each other in line with the One Health objectives.

[Upcoming value of gene expression analysis in rheumatology]

Rheumatoid arthritis (RA) is a chronic inflammatory disease of unknown etiology, which involves disturbance in immune system signaling pathway functions, damage of other tissues, pain and joint destruction. Modern treatment attempts to improve pathophysiological and biochemical mechanisms damaged by the disease. However, due to the RA patient heterogeneity personalized approach to treatment is required; the choice of personalized treatment is complicated by the variability of patient's response to treatment. Gene expression analysis might serve a tool for the disease control and therapy personification for inhibition of inflammation and pain as well as for prevention of joint destruction.

Recombinant interferon alpha 2b in rheumatoid arthritis: good antigen for rheumatoid arthritis antibodies

Aim of the study

Interferon alpha-induced arthritis and activation of the type 1 interferon pathway during rheumatoid arthritis (RA) has been well documented but the underlying mechanism remains unclear. This study addressed the binding specificity of antibodies with recombinant interferon alpha 2b (rIFN α-2b) in sera from different RA patients. Utilization of anti-hrIFN α-2b antibodies as a probe for estimation of interferon α-2b concentration in RA patients’ synovial fluid (SF) was also investigated.

Material and methods

Binding specificities of antibodies from the sera of 60 RA patients and 35 controls subjects were studied by direct binding, inhibition ELISA, and quantitative precipitation titration. Inhibition ELISA was also used to estimate patients’ SF interferon α-2b concentrations.

Results

RA IgG from patients’ sera showed strong recognition to hrIFN α-2b in comparison to commercially available interferon (IFN α-2b) (p < 0.05) or the gene encoding this interferon (IFN α-2b gene) (p < 0.05). The affinity of RA antibodies for rIFN α-2b (1.10 × 10^–7 M) was found to be high as assessed by Langmuir plot. No significant difference in the level of interferon α in the SF of RA patients was observed as compared to the healthy controls.

Conclusions

rIFN α-2b presents unique epitopes that might explain the possible antigenic role in the induction of RA antibodies and anti-rIFN α-2b antibodies represent an alternative immunological probe for the estimation of interferon α in the SF of RA patients.

Potential role of type I interferon in the pathogenic process leading to type 1 diabetes

PURPOSE OF REVIEW

Understanding the relationship between viral infections and the development of type 1 diabetes (T1D) is essential for T1D prevention. Virus-induced innate immune responses, specifically type I interferon (IFN-I) and the IFN gene signature, orchestrate early events of β-cell dysfunction preceding islet autoimmunity. We summarize recent advances in how IFN-I and the IFN gene signature can drive T1D development.

RECENT FINDINGS

IFN-I, particularly IFN-α, and the IFN gene signature have been detected in islets and peripheral blood of T1D patients. T1D risk genes in the IFN-I signaling pathway regulate antiviral responses in β cells driven by IFN-I and proinflammatory cytokines. Polymorphisms in these genes may cause chronic dysregulated IFN signaling in islets, characterized by hyperexpression of IFN-I, the IFN gene signature, and major histocompatibility complex class I during viral infection. Islet-cell inflammation mediated by aberrant IFN signaling drives β-cell apoptosis by initiating autoreactivity against β-cell antigens. The profound elevation in IFN-I and the IFN gene signature observed in some forms of T1D are also seen in a novel group of human autoimmune and autoinflammatory diseases called interferonopathies.

SUMMARY

Despite significant advances, further studies are required to functionally dissect the mechanisms by which excessive IFN-I contributes to the evolution of autoimmunity that destroys β cells.

Breaking self-tolerance during autoimmunity and cancer immunity: Myeloid cells and type I IFN response regulation

The generation and regulation of innate immune signals are key determinants of autoimmune pathogenesis. Emerging evidence suggests that parallel processes operating in the setting of solid tumors can similarly determine the balance between tolerance and immunity and ultimately the effectiveness of the antitumor immune response. In both contexts, self-specific responses start with innate immune cell activation that leads to the initial break in self-tolerance, which can be followed by immune response amplification and maturation through innate-adaptive crosstalk, and finally immune-mediated tissue/tumor destruction that can further potentiate inflammation. Of particular importance for these processes is type I IFN, which is induced in response to endogenous ligands, such as self-nucleic acids, and acts on myeloid cells to promote the expansion of autoreactive or tumor-specific T cells and their influx into the target tissue. Evidence from the study of human disease pathophysiology and genetics and mouse models of disease has revealed an extensive and complex network of negative regulatory pathways that has evolved to restrain type I IFN production and activity. Here, we review the overlapping features of self- and tumor-specific immune responses, including the central role that regulators of the type I IFN response and innate immune cell activation play in maintaining tolerance, and discuss how a better understanding of the pathophysiology of autoimmunity can help to identify new approaches to promote immune-mediated tumor destruction.

Right drug, right patient, right time: aspiration or future promise for biologics in rheumatoid arthritis?

Individualising biologic disease-modifying anti-rheumatic drugs (bDMARDs) to maximise outcomes and deliver safe and cost-effective care is a key goal in the management of rheumatoid arthritis (RA). Investigation to identify predictive tools of bDMARD response is a highly active and prolific area of research. In addition to clinical phenotyping, cellular and molecular characterisation of synovial tissue and blood in patients with RA, using different technologies, can facilitate predictive testing. This narrative review will summarise the literature for the available bDMARD classes and focus on where progress has been made. We will also look ahead and consider the increasing use of 'omics' technologies, the potential they hold as well as the challenges, and what is needed in the future to fully realise our ambition of personalised bDMARD treatment.

The clinical utility of gene expression examination in rheumatology

Rheumatoid arthritis (RA) is a chronic inflammatory disease with unknown etiology that affects various pathways within the immune system, involves many other tissues and is associated with pain and joint destruction. Current treatments fail to address pathophysiological and biochemical mechanisms involved in joint degeneration and the induction of pain. Moreover, RA patients are extremely heterogeneous and require specific treatments, the choice of which is complicated by the fact that not all patients equally respond to therapy. Gene expression analysis offer tools for patient management and personalization of patient’s care to meet individual needs in controlling inflammation and pain and delaying joint destruction.

Type 1 Interferons Induce Changes in Core Metabolism that Are Critical for Immune Function

Greater understanding of the complex host responses induced by type 1 interferon (IFN) cytokines could allow new therapeutic approaches for diseases in which these cytokines are implicated. We found that in response to the Toll-like receptor-9 agonist CpGA, plasmacytoid dendritic cells (pDC) produced type 1 IFNs, which, through an autocrine type 1 IFN receptor-dependent pathway, induced changes in cellular metabolism characterized by increased fatty acid oxidation (FAO) and oxidative phosphorylation (OXPHOS). Direct inhibition of FAO and of pathways that support this process, such as fatty acid synthesis, prevented full pDC activation. Type 1 IFNs also induced increased FAO and OXPHOS in non-hematopoietic cells and were found to be responsible for increased FAO and OXPHOS in virus-infected cells. Increased FAO and OXPHOS in response to type 1 IFNs was regulated by PPARα. Our findings reveal FAO, OXPHOS and PPARα as potential targets to therapeutically modulate downstream effects of type 1 IFNs.

Down-regulation of miR-10a-5p in synoviocytes contributes to TBX5-controlled joint inflammation

MicroRNAs are considered to play critical roles in the pathogenesis of human inflammatory arthritis, including rheumatoid arthritis (RA). The purpose of this study was to determine the relationship between miR‐10a‐5p and TBX5 in synoviocytes and evaluate their contribution to joint inflammation. The expression of miR‐10a‐5p and TBX5 in the synovium of RA and human synovial sarcoma cell line SW982 stimulated by IL‐1β was determined by RT‐qPCR and Western blotting. The direct interaction between miR‐10a‐5p and TBX5 3′UTR was determined by dual‐luciferase reporter assay in HeLa cells. Mimics and inhibitors of miR‐10a‐5p were transfected into SW982 cells. TBX5 was overexpressed by plasmid transfection or knocked down by RNAi. Proinflammatory cytokines and TLR3 and MMP13 expressions were determined by RT‐qPCR and Western blotting. Down‐regulated expression of miR‐10a‐5p and up‐regulation of TBX5 in human patients with RA were found compared to patients with OA. IL‐1β could reduce miR‐10a‐5p and increase TBX5 expression in SW982 cells in vitro. The direct target relationship between miR‐10a‐5p and 3′UTR of TBX5 was confirmed by luciferase reporter assay. Alterations of miR‐10‐5p after transfection with its mimic and inhibitor caused the related depression and re‐expression of TBX5 and inflammatory factors in SW982 cells. Overexpression of TBX5 after pCMV3‐TBX5 plasmid transfection significantly promoted the production of TLR3, MMP13 and various inflammatory cytokines, while this effect was rescued after knocking down of TBX5 with its specific siRNA. We conclude that miR‐10a‐5p in a relation with TBX5 regulates joint inflammation in arthritis, which would serve as a diagnostic and therapeutic target for RA treatment.

Identification of a Sjögren's syndrome susceptibility locus at OAS1 that influences isoform switching, protein expression, and responsiveness to type I interferons

Sjögren's syndrome (SS) is a common, autoimmune exocrinopathy distinguished by keratoconjunctivitis sicca and xerostomia. Patients frequently develop serious complications including lymphoma, pulmonary dysfunction, neuropathy, vasculitis, and debilitating fatigue. Dysregulation of type I interferon (IFN) pathway is a prominent feature of SS and is correlated with increased autoantibody titers and disease severity. To identify genetic determinants of IFN pathway dysregulation in SS, we performed cis-expression quantitative trait locus (eQTL) analyses focusing on differentially expressed type I IFN-inducible transcripts identified through a transcriptome profiling study. Multiple cis-eQTLs were associated with transcript levels of 2'-5'-oligoadenylate synthetase 1 (OAS1) peaking at rs10774671 (PeQTL = 6.05 × 10-14). Association of rs10774671 with SS susceptibility was identified and confirmed through meta-analysis of two independent cohorts (Pmeta = 2.59 × 10-9; odds ratio = 0.75; 95% confidence interval = 0.66-0.86). The risk allele of rs10774671 shifts splicing of OAS1 from production of the p46 isoform to multiple alternative transcripts, including p42, p48, and p44. We found that the isoforms were differentially expressed within each genotype in controls and patients with and without autoantibodies. Furthermore, our results showed that the three alternatively spliced isoforms lacked translational response to type I IFN stimulation. The p48 and p44 isoforms also had impaired protein expression governed by the 3' end of the transcripts. The SS risk allele of rs10774671 has been shown by others to be associated with reduced OAS1 enzymatic activity and ability to clear viral infections, as well as reduced responsiveness to IFN treatment. Our results establish OAS1 as a risk locus for SS and support a potential role for defective viral clearance due to altered IFN response as a genetic pathophysiological basis of this complex autoimmune disease.

Pregnancy-induced gene expression changes in vivo among women with rheumatoid arthritis: a pilot study

BACKGROUND

Little is known about gene expression changes induced by pregnancy in women with rheumatoid arthritis (RA) and healthy women because the few studies previously conducted did not have pre-pregnancy samples available as baseline. We have established a cohort of women with RA and healthy women followed prospectively from a pre-pregnancy baseline. In this study, we tested the hypothesis that pregnancy-induced changes in gene expression among women with RA who improve during pregnancy (pregDAS_improved) overlap substantially with changes observed among healthy women and differ from changes observed among women with RA who worsen during pregnancy (pregDAS_worse).

METHODS

Global gene expression profiles were generated by RNA sequencing (RNA-seq) from 11 women with RA and 5 healthy women before pregnancy (T0) and at the third trimester (T3). Among the women with RA, eight showed an improvement in disease activity by T3, whereas three worsened. Differential expression analysis was used to identify genes demonstrating significant changes in expression within each of the RA and healthy groups (T3 vs T0), as well as between the groups at each time point. Gene set enrichment was assessed in terms of Gene Ontology processes and protein networks.

RESULTS

A total of 1296 genes were differentially expressed between T3 and T0 among the 8 pregDAS_improved women, with 161 genes showing at least two-fold change (FC) in expression by T3. The majority (108 of 161 genes) were also differentially expressed among healthy women (q<0.05, FC≥2). Additionally, a small cluster of genes demonstrated contrasting changes in expression between the pregDAS_improved and pregDAS_worse groups, all of which were inducible by type I interferon (IFN). These IFN-inducible genes were over-expressed at T3 compared to the T0 baseline among the pregDAS_improved women.

CONCLUSIONS

In our pilot RNA-seq dataset, increased pregnancy-induced expression of type I IFN-inducible genes was observed among women with RA who improved during pregnancy, but not among women who worsened. These findings warrant further investigation into expression of these genes in RA pregnancy and their potential role in modulation of disease activity. These results are nevertheless preliminary and should be interpreted with caution until replicated in a larger sample.

A Critical Role for the Type I Interferon Receptor in Virus-Induced Autoimmune Diabetes in Rats

The pathogenesis of human type 1 diabetes, characterized by immune-mediated damage of insulin-producing β-cells of pancreatic islets, may involve viral infection. Essential components of the innate immune antiviral response, including type I interferon (IFN) and IFN receptor-mediated signaling pathways, are candidates for determining susceptibility to human type 1 diabetes. Numerous aspects of human type 1 diabetes pathogenesis are recapitulated in the LEW.1WR1 rat model. Diabetes can be induced in LEW.1WR1 weanling rats challenged with virus or with the viral mimetic polyinosinic:polycytidylic acid (poly I:C). We hypothesized that disrupting the cognate type I IFN receptor (type I IFN α/β receptor [IFNAR]) to interrupt IFN signaling would prevent or delay the development of virus-induced diabetes. We generated IFNAR1 subunit-deficient LEW.1WR1 rats using CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-associated protein 9) genome editing and confirmed functional disruption of the Ifnar1 gene. IFNAR1 deficiency significantly delayed the onset and frequency of diabetes and greatly reduced the intensity of insulitis after poly I:C treatment. The occurrence of Kilham rat virus-induced diabetes was also diminished in IFNAR1-deficient animals. These findings firmly establish that alterations in innate immunity influence the course of autoimmune diabetes and support the use of targeted strategies to limit or prevent the development of type 1 diabetes.

Dendritic Cells in Systemic Lupus Erythematosus: From Pathogenic Players to Therapeutic Tools

System lupus erythematosus (SLE) is a multifactorial systemic autoimmune disease with a wide variety of presenting features. SLE is believed to result from dysregulated immune responses, loss of tolerance of CD4 T cells and B cells to ubiquitous self-antigens, and the subsequent production of anti-nuclear and other autoreactive antibodies. Recent research has associated lupus development with changes in the dendritic cell (DC) compartment, including altered DC subset frequency and localization, overactivation of mDCs and pDCs, and functional defects in DCs. Here we discuss the current knowledge on the role of DC dysfunction in SLE pathogenesis, with the focus on DCs as targets for interventional therapies.

Anti-BDCA2 monoclonal antibody inhibits plasmacytoid dendritic cell activation through Fc-dependent and Fc-independent mechanisms

Type I interferons (IFN-I) are implicated in the pathogenesis of systemic lupus erythematosus (SLE). In SLE, immune complexes bind to the CD32a (FcγRIIa) receptor on the surface of plasmacytoid dendritic cells (pDCs) and stimulate the secretion of IFN-I from pDCs. BDCA2 is a pDC-specific receptor that, when engaged, inhibits the production of IFN-I in human pDCs. BDCA2 engagement, therefore, represents an attractive therapeutic target for inhibiting pDC-derived IFN-I and may be an effective therapy for the treatment of SLE. In this study, we show that 24F4A, a humanized monoclonal antibody (mAb) against BDCA2, engages BDCA2 and leads to its internalization and the consequent inhibition of TLR-induced IFN-I by pDCs in vitro using blood from both healthy and SLE donors. These effects were confirmed in vivo using a single injection of 24F4A in cynomolgus monkeys. 24F4A also inhibited pDC activation by SLE-associated immune complexes (IC). In addition to the inhibitory effect of 24F4A through engagement of BDCA2, the Fc region of 24F4A was critical for potent inhibition of IC-induced IFN-I production through internalization of CD32a. This study highlights the novel therapeutic potential of an effector-competent anti-BDCA2 mAb that demonstrates a dual mechanism to dampen pDC responses for enhanced clinical efficacy in SLE.

Effects of type 1 diabetes-associated IFIH1 polymorphisms on MDA5 function and expression

Recent evidence has highlighted the role of the innate immune system in type 1 diabetes (T1D) pathogenesis. Specifically, aberrant activation of the interferon response prior to seroconversion of T1D-associated autoantibodies supports a role for the interferon response as a precipitating event toward activation of autoimmunity. Melanoma differentiation-associated protein 5 (MDA5), encoded by IFIH1, mediates the innate immune system's interferon response to certain viral species that form double-stranded RNA (dsRNA), the MDA5 ligand, during their life cycle. Extensive research has associated single nucleotide polymorphisms (SNPs) within the coding region of IFIH1 with T1D. This review discusses the different risk and protective IFIH1 alleles in the context of recent structural and functional analysis that relate to MDA5 regulation of interferon responses. These studies have provided a functional hypothesis for IFIH1 T1D-associated SNPs' effects on MDA5-mediated interferon responses as well as supporting the genome-wide association (GWA) studies that first associated IFIH1 with T1D.