Type I Interferons in Autoimmune Disease

Unveiling biomarkers and therapeutic targets in IgA nephropathy through large-scale blood transcriptome analysis

INTRODUCTION

IgA nephropathy (IgAN) is the most prevalent form of glomerulonephritis. Unfortunately, molecular biomarkers for IgAN derived from omics studies are still lacking. This research aims to identify critical genes associated with IgAN through large-scale blood transcriptome analysis.

METHODS

We constructed novel blood transcriptome profiles from peripheral blood mononuclear cells (PBMCs) of 53 Chinese IgAN patients and 28 healthy individuals. Our analysis included GO, KEGG, and GSEA for biological pathways. We analyzed immune cell profiles with CIBERSORT and constructed PPI networks with STRING, visualized in Cytoscape. Key differentially expressed genes (DEGs) were identified using CytoHubba and MCODE. We assessed the correlation between gene expressions and clinical data to evaluate clinical significance and identified hub genes through machine learning, validated with an open-access dataset. Potential drugs were explored using the CMap database.

RESULTS

We identified 333 DEGs between IgAN patients and healthy controls, mainly related to immune response and inflammation. Key pathways included NK cell mediated cytotoxicity, complement and coagulation cascades, antigen processing, and B cell receptor signaling. Cytoscape revealed 16 clinically significant genes (including KIR2DL1, KIR2DL3, VISIG4, C1QB, and C1QC, associated with sub-phenotype and prognosis). Machine learning identified two hub genes (KLRC1 and C1QB) for a diagnostic model of IgAN with 0.92 accuracy, validated at 1.00 against the GSE125818 dataset. Sirolimus, calcifediol, and efaproxiral were suggested as potential therapeutic agents.

CONCLUSION

Key DEGs, particularly VISIG4, KLRC1, and C1QB, emerge as potential specific markers for IgAN, paving the way for future targeted personalized treatment options.

Z-nucleic acid sensor ZBP1 in sterile inflammation

Z-DNA binding protein 1 (ZBP1), a cytosolic nucleic acid sensor for Z-form nucleic acids (Z-NA), can detect both exogenous and endogenous nucleic acids. Upon sensing of self Z-NA or exposure to diverse noxious stimuli, ZBP1 regulates inflammation by activating nuclear factor kappa B and interferon regulating factor 3 signaling pathways. In addition, ZBP1 promotes the assembly of ZBP1 PANoptosome, which initiates caspase 3-mediated apoptosis, mixed lineage kinase domain like pseudokinase (MLKL)-mediated necroptosis, and gasdermin D (GSDMD)-mediated pyroptosis (PANoptosis), leading to the release of various damage-associated molecular patterns. Thereby, ZBP1 is implicated in the development and progression of diverse sterile inflammatory diseases. This review outlines the expression, structure, and function of ZBP1, along with its dual roles in controlling inflammation and cell death to orchestrate innate immunity in sterile inflammation, especially autoimmune diseases, and cancers. ZBP1 has emerged as an attractive therapeutic target for various sterile inflammatory diseases.

Enhanced GATA4 expression in senescent systemic lupus erythematosus monocytes promotes high levels of IFNα production

Enhanced interferon α (IFNα) production has been implicated in the pathogenesis of systemic lupus erythematosus (SLE). We previously reported IFNα production by monocytes upon activation of the stimulator of IFN genes (STING) pathway was enhanced in patients with SLE. We investigated the mechanism of enhanced IFNα production in SLE monocytes. Monocytes enriched from the peripheral blood of SLE patients and healthy controls (HC) were stimulated with 2'3'-cyclic GAMP (2'3'-cGAMP), a ligand of STING. IFNα positive/negative cells were FACS-sorted for RNA-sequencing analysis. Gene expression in untreated and 2'3'-cGAMP-stimulated SLE and HC monocytes was quantified by real-time PCR. The effect of GATA binding protein 4 (GATA4) on IFNα production was investigated by overexpressing GATA4 in monocytic U937 cells by vector transfection. Chromatin immunoprecipitation was performed to identify GATA4 binding target genes in U937 cells stimulated with 2'3'-cGAMP. Differentially expressed gene analysis of cGAS-STING stimulated SLE and HC monocytes revealed the enrichment of gene sets related to cellular senescence in SLE. CDKN2A, a marker gene of cellular senescence, was upregulated in SLE monocytes at steady state, and its expression was further enhanced upon STING stimulation. GATA4 expression was upregulated in IFNα-positive SLE monocytes. Overexpression of GATA4 enhanced IFNα production in U937 cells. GATA4 bound to the enhancer region of IFIT family genes and promoted the expressions of IFIT1, IFIT2, and IFIT3, which promote type I IFN induction. SLE monocytes with accelerated cellular senescence produced high levels of IFNα related to GATA4 expression upon activation of the cGAS-STING pathway.

The trajectory of human B-cell function, immune deficiency, and allergy revealed by inborn errors of immunity

The essential role of B cells is to produce protective immunoglobulins (Ig) that recognize, neutralize, and clear invading pathogens. This results from the integration of signals provided by pathogens or vaccines and the stimulatory microenvironment within sites of immune activation, such as secondary lymphoid tissues, that drive mature B cells to differentiate into memory B cells and antibody (Ab)-secreting plasma cells. In this context, B cells undergo several molecular events including Ig class switching and somatic hypermutation that results in the production of high-affinity Ag-specific Abs of different classes, enabling effective pathogen neutralization and long-lived humoral immunity. However, perturbations to these key signaling pathways underpin immune dyscrasias including immune deficiency and autoimmunity or allergy. Inborn errors of immunity that disrupt critical immune pathways have identified non-redundant requirements for eliciting and maintaining humoral immune memory but concomitantly prevent immune dysregulation. Here, we will discuss our studies on human B cells, and how our investigation of cytokine signaling in B cells have identified fundamental requirements for memory B-cell formation, Ab production as well as regulating Ig class switching in the context of protective versus allergic immune responses.

Neutrophil-plasmacytoid dendritic cell interaction leads to production of type I IFN in response to Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) can cause a latent infection that sometimes progresses to clinically active tuberculosis (TB). Type I interferons (IFN-I) have been implicated in initiating the progression from latency to active TB, in part because IFN-I stimulated genes are the earliest genes to be upregulated in patients as they advance to active TB. Plasmacytoid dendritic cells (pDCs) are major producers of IFN-I during viral infections and in response to autoimmune-induced neutrophil extracellular traps. pDCs have also been suggested to be the major producers of IFN-I during Mtb infection of mice and nonhuman primates, but direct evidence has been lacking. Here, we found that Mtb did not stimulate isolated human pDCs to produce IFN-I, but human neutrophils infected with Mtb-activated co-cultured pDCs to do so. Mtb-infected neutrophils produced neutrophil extracellular traps, whose exposed DNA is a well-known mechanism to activate pDCs to secrete IFN-I. We conclude that pDCs contribute to the IFN-I response during Mtb infection by interacting with infected neutrophils which may then promote Mtb pathogenesis.

Type 1 interferons: A target for immune-mediated inflammatory diseases (IMIDs)

The improved understanding of the molecular basis of innate immunity have led to the identification of type I interferons (IFNs), particularly IFN-α, as central mediators in the pathogenesis of several Immune-mediated inflammatory diseases (IMIDs) such as systemic lupus erythematosus (SLE), systemic sclerosis, inflammatory myositis and Sjögren's syndrome. Here, we review the main data regarding the opportunity to target type I IFNs for the treatment of IMIDs. Type I IFNs and their downstream pathways can be targeted pharmacologically in several manners. One approach is to use monoclonal antibodies against IFNs or the IFN-receptors (IFNARs, such as with anifrolumab). The downstream signaling pathways of type I IFNs also contain several targets of interest in IMIDs, such as JAK1 and Tyk2. Of these, anifrolumab is licensed and JAK1/Tyk2 inhibitors are in phase III trials in SLE. Targeting IFN-Is for the treatment of SLE is already a reality and in the near future may prove useful in other IMIDs. IFN assays will find a role in routine clinical practice for the care of IMIDs as further validation work is completed and a greater range of targeted therapies becomes available.

Chronic endoplasmic reticulum stress in myotonic dystrophy type 2 promotes autoimmunity via mitochondrial DNA release

Myotonic dystrophy type 2 (DM2) is a tetranucleotide CCTG repeat expansion disease associated with an increased prevalence of autoimmunity. Here, we identified an elevated type I interferon (IFN) signature in peripheral blood mononuclear cells and primary fibroblasts of DM2 patients as a trigger of chronic immune stimulation. Although RNA-repeat accumulation was prevalent in the cytosol of DM2-patient fibroblasts, type-I IFN release did not depend on innate RNA immune sensors but rather the DNA sensor cGAS and the prevalence of mitochondrial DNA (mtDNA) in the cytoplasm. Sublethal mtDNA release was promoted by a chronic activation of the ATF6 branch of the unfolded protein response (UPR) in reaction to RNA-repeat accumulation and non-AUG translated tetrapeptide expansion proteins. ATF6-dependent mtDNA release and resulting cGAS/STING activation could also be recapitulated in human THP-1 monocytes exposed to chronic endoplasmic reticulum (ER) stress. Altogether, our study demonstrates a novel mechanism by which large repeat expansions cause chronic endoplasmic reticulum stress and associated mtDNA leakage. This mtDNA is, in turn, sensed by the cGAS/STING pathway and induces a type-I IFN response predisposing to autoimmunity. Elucidating this pathway reveals new potential therapeutic targets for autoimmune disorders associated with repeat expansion diseases.

Inflammatory Cytokines Can Induce Synthesis Of Type-I Interferon

Type I interferon (IFN) is induced in virus infected cells, secreted and it inhibits viral replication in neighboring cells. IFN is also an important player in many non-viral diseases and in the development of normal immune cells. Although the signaling pathways for IFN induction by viral RNA or DNA have been extensively studied, its mode of induction in uninfected cells remains obscure. Here, we report that inflammatory cytokines, such as TNF-α and IL-1β, can induce IFN-β through activation of the cytoplasmic RIG-I signaling pathway. However, RIG-I is activated not by RNA, but by PACT, the protein activator of PKR. In cell lines or primary cells expressing RIG-I and PACT, activation of the MAPK, p38, by cytokine signaling, leads to phosphorylation of PACT, which binds to primed RIG-I and activates its signaling pathway. Thus, a new mode of type I IFN induction by ubiquitous inflammatory cytokines has been revealed.

Key points

Cytochalasin D followed by TNF-α / IL-1β treatment activates IFN-β expression.IFN-β expression happens due to activation of RIG-I signaling.Interaction between RIG-I and PACT activates IFN-β expression.

Functional characterization of group Ⅱ interferon, IFNf in the acipenseriform fish, Chinese sturgeon (Acipenser sinensis)

Teleost fish possess a diversity of type Ⅰ interferons (IFNs) repertoire, which play a crucial role in antiviral and antimicrobial immune responses. In our previous study, IFNe1-3 and IFNb were identified and cloned from Chinese sturgeon (Acipenser sinensis), an acipenseriform fish. However, the absence of Chinese sturgeon genome data has left the question of whether there are other type Ⅰ IFN members in this species unresolved. In this study, we have identified and characterized a novel IFN, IFNf in Chinese sturgeon (AsIFNf). Bioinformatics analysis revealed that the AsIFNf contains a unique disulfide bond (2 cysteines) located in the second exon and fifth exon region, distinguishing it from other reported teleost type I IFNs. Meanwhile, qPCR results showed that AsIFNf mRNA was detectable in all examined tissues and up-regulated in the spleen or kidney in response to poly I: C, Citrobacter freundii, and Spring Viremia of Carp Virus (SVCV), but not by LPS. Furthermore, compared to recombinant AsIFNe2 protein (rAsIFNe2), rAsIFNf exhibited a stronger protective effect on Chinese sturgeon fin cells against SVCV and also induced higher expression of antiviral genes Mx and viperin. Importantly, AsIFNf displayed characteristics similar to antimicrobial peptides (AMPs) with a positive charge and demonstrated a broad spectrum of antimicrobial activity in vitro. These findings provide a theoretical foundation for understanding the primitive structure and function of interferon, as well as deepening our comprehension of the innate immune system and disease defense in the endangered Chinese sturgeon.

Emerging roles of SnoRNAs in the pathogenesis and treatment of autoimmune disorders

SnoRNAs (small non-coding RNAs) have recently gained prominence in autoimmune diseases, revealing their crucial role in modulating the immune response and contributing to disease pathogenesis. Initially known for their involvement in ribosomal RNA processing and modification, molecular biology and genomics advancements have uncovered their broader impact on cellular function, especially in autoimmune disorders. Autoimmune diseases represent conditions characterized by the immune system's erroneous attacks on self-tissues, encompassing disorders like systemic lupus erythematosus, rheumatoid arthritis, and multiple sclerosis. The complex etiology of these conditions involves a delicate interplay of genetic and environmental factors. Emerging evidence suggests that snoRNAs initially recognized for their housekeeping roles, extend their influence on immune regulation through diverse mechanisms. SnoRNAs have been implicated in epigenetic modification, directly affecting the gene expression profiles of immune cells. Their ability to guide site-specific changes on ribosomal RNAs and other non-coding RNAs can significantly influence the translation of proteins involved in immune response pathways. Moreover, snoRNAs interact with key immune-related proteins, modulating their functions and subsequently impacting immune cell development, activation, and tolerance. Dysregulation of snoRNA expression has been observed in various autoimmune diseases, underscoring their potential as biomarkers for disease diagnosis, prognosis, and therapeutic targets. Manipulating snoRNA expression or activity is a promising therapeutic intervention avenue, offering the potential for personalized treatment strategies in autoimmune diseases. However, there remains a need for comprehensive research efforts to elucidate the precise molecular mechanisms underlying snoRNA-mediated immune modulation. Further investigations in this domain are essential to unravel the potential of snoRNAs in autoimmune disorders.

Autophagy as a dual-faced host response to viral infections

Autophagy selectively degrades viral particles or cellular components, either facilitating or inhibiting viral replication. Conversely, most viruses have evolved strategies to escape or exploit autophagy. Moreover, autophagy collaborates with the pattern recognition receptor signaling, influencing the expression of adaptor molecules involved in the innate immune response and regulating the expression of interferons (IFNs). The intricate relationship between autophagy and IFNs plays a critical role in the host cell defense against microbial invasion. Therefore, it is important to summarize the interactions between viral infections, autophagy, and the host defense mechanisms against viruses. This review specifically focuses on the interactions between autophagy and IFN pathways during viral infections, providing a comprehensive summary of the molecular mechanisms utilized or evaded by different viruses.

Emerging immunotherapeutic strategies for cutaneous lupus erythematosus: an overview of recent phase 2 and 3 clinical trials

INTRODUCTION

Cutaneous lupus erythematosus (CLE) is an autoimmune disease that is clinically heterogenous and may occur with or without the presence of systemic lupus erythematosus (SLE). While existing on a spectrum, CLE and SLE present differences in their underlying pathogenesis and therapeutic responses. No new therapies have been approved in recent decades by the U.S. Food and Drug Administration for CLE, although frequently refractory to conventional therapies. There is an unmet need to develop effective drugs for CLE as it significantly impacts patients' quality of life and may leave irreversible disfiguring damage.

AREAS COVERED

This review provides an update on the latest phase 2 and 3 clinical trials performed in CLE or SLE using skin-specific outcome measures. Emergent therapies are presented alongside their mechanism of action as recent translational studies have permitted identification of critical targets among immune cells and/or pathways involved in CLE.

EXPERT OPINION

While the recent literature has few trials for CLE, drugs targeting type I interferon, its downstream signaling and plasmacytoid dendritic cells have shown promising results. Further research is required to develop long-awaited effective therapies, and this review highlights the importance of implementing trials dedicated to CLE to fill the current gap in CLE therapeutics.

A comprehensive analysis of type 1 interferon gene signatures in systematic lupus erythematosus and prediction of the crucial susceptible factor for Sjögren syndrome

This study aimed to determine the role of IFN-1 gene signatures in SLE and their association with Sjögren syndrome (SS). Publicly available data from the Gene Expression Omnibus database were used to construct the models. The random forest tree model was used to screen key IFN-1 gene signatures, and consensus clustering algorithms were used for unsupervised cluster analysis of these signatures. CIBERSORT and gene set variation analyses were used to evaluate the relative immune cell infiltration and enriched molecular pathways of the samples, respectively. Weighted gene co-expression network analysis was used to identify the co-expression modules and hub genes. Finally, univariate and multivariate logistic regression models were used to evaluate differences in clinical and laboratory characteristics between the different groups. The role of IFN-1 gene signatures in SLE was comprehensively assessed, which revealed an IFN-1 gene signature including six genes that could easily distinguish SLE patients and healthy individuals and identified two distinct IFN-1 subtypes exhibiting significant differences in clinical characteristics, immune microenvironment, and biological functional pathways. The SLE disease activity index, lower lymphocyte count, nucleotide oligomerization domain (NOD)-like receptor signaling pathway, and dendritic cell activation were strongly correlated with the IFN-1 gene signatures. In addition, we found that IFN-1 gene signatures in SLE may be an important susceptibility factor for SS, and the NOD-like receptor signaling pathway was identified as a common pathway. This study provides a comprehensive evaluation of the IFN-1 gene signatures, which may provide a new direction for the understanding of SLE and SS and help in the selection of optimal strategies for personalized immunotherapy.

Ceftazidime reduces cellular Skp2 to promote type-I interferon activity

Skp2 plays multiple roles in malignant tumours. Here, we revealed that Skp2 negatively regulates type-I interferon (IFN-I)-mediated antiviral activity. We first noticed that Skp2 can promote virus infection in cells. Further studies demonstrated that Skp2 interacts with IFN-I receptor 2 (IFNAR2) and promotes K48-linked polyubiquitination of IFNAR2, which accelerates the degradation of IFNAR2 proteins. Skp2-mediated downregulation of IFNAR2 levels inhibits IFN-I signalling and IFN-I-induced antiviral activity. In addition, we uncovered for the first time that the antibiotic ceftazidime can act as a repressor of Skp2. Ceftazidime reduces cellular Skp2 levels, thus enhancing IFNAR2 stability and IFN-I antiviral activity. This study reveals a new role of Skp2 in regulating IFN-I signalling and IFN-I antiviral activity and reports the antibiotic ceftazidime as a potential repressor of Skp2.

Discovery of WD-890: A novel allosteric TYK2 inhibitor for the treatment of multiple autoimmune diseases

Tyrosine kinase 2 (TYK2) as a member of Janus kinase (JAK) family, mainly mediates the signaling of type I interferons (IFN), interleukin-12 (IL-12) and interleukin-23 (IL-23), which has become an attractive target for treatment of immune and inflammatory diseases. However, the development of selective TYK2 inhibitors is challenging due to the high homology of the catalytic kinase domain among the JAK family members. Here, we report a novel and potent allosteric inhibitor, WD-890, which binds to the pseudokinase domain of TYK2 with high selectivity and inhibits its function. We accomplished a series of preclinical studies to demonstrate the therapeutic efficacy of WD-890 in four animal models: systemic lupus erythematosus (SLE), psoriasis, psoriatic arthritis (PsA), and inflammatory bowel disease (IBD). The pharmacokinetic and toxicology results further indicate that WD-890 has favorable absorption, distribution, metabolism, and excretion (ADME) properties and tolerable toxicity. In conclusion, our study shows that WD-890 could be a promising oral TYK2 inhibitor for future treatment of autoimmune diseases.

Enzymolysis-based RNA pull-down identifies YTHDC2 as an inhibitor of antiviral innate response

The innate immune response must be terminated in a timely manner at the late stage of infection to prevent unwanted inflammation. The role of m6A-modified RNAs and their binding partners in this process is not well known. Here, we develop an enzymolysis-based RNA pull-down (eRP) method that utilizes the immunoglobulin G-degrading enzyme of Streptococcus pyogenes (IdeS) to fish out m6A-modified RNA-associated proteins. We apply eRP to capture the methylated single-stranded RNA (ssRNA) probe-associated proteins and identify YT521-B homology domain-containing 2 (YTHDC2) as the m6A-modified interferon β (IFN-β) mRNA-binding protein. YTHDC2, induced in macrophages at the late stage of virus infection, recruits IFN-stimulated exonuclease ISG20 (IFN-stimulated exonuclease gene 20) to degrade IFN-β mRNA, consequently inhibiting antiviral innate immune response. In vitro and in vivo deficiency of YTHDC2 increases IFN-β production at the late stage of viral infection. Our findings establish an eRP method to effectively identify RNA-protein interactions and add mechanistic insight to the termination of innate response for maintaining homeostasis.

Long 3'UTRs predispose neurons to inflammation by promoting immunostimulatory double-stranded RNA formation

Loss of RNA homeostasis underlies numerous neurodegenerative and neuroinflammatory diseases. However, the molecular mechanisms that trigger neuroinflammation are poorly understood. Viral double-stranded RNA (dsRNA) triggers innate immune responses when sensed by host pattern recognition receptors (PRRs) present in all cell types. Here, we report that human neurons intrinsically carry exceptionally high levels of immunostimulatory dsRNAs and identify long 3'UTRs as giving rise to neuronal dsRNA structures. We found that the neuron-enriched ELAVL family of genes (ELAVL2, ELAVL3, and ELAVL4) can increase (i) 3'UTR length, (ii) dsRNA load, and (iii) activation of dsRNA-sensing PRRs such as MDA5, PKR, and TLR3. In wild-type neurons, neuronal dsRNAs signaled through PRRs to induce tonic production of the antiviral type I interferon. Depleting ELAVL2 in WT neurons led to global shortening of 3'UTR length, reduced immunostimulatory dsRNA levels, and rendered WT neurons susceptible to herpes simplex virus and Zika virus infection. Neurons deficient in ADAR1, a dsRNA-editing enzyme mutated in the neuroinflammatory disorder Aicardi-Goutières syndrome, exhibited intolerably high levels of dsRNA that triggered PRR-mediated toxic inflammation and neuronal death. Depleting ELAVL2 in ADAR1 knockout neurons led to prolonged neuron survival by reducing immunostimulatory dsRNA levels. In summary, neurons are specialized cells where PRRs constantly sense "self" dsRNAs to preemptively induce protective antiviral immunity, but maintaining RNA homeostasis is paramount to prevent pathological neuroinflammation.

MAURIVAX: A Vaccination Campaign Project in a Hospital Environment for Patients Affected by Autoimmune Diseases and Adult Primary Immunodeficiencies

Background: Patients with autoimmune diseases (ADs) and primary immunodeficiencies (PIDs) are characterized by an increased risk of noninvasive and widespread infections as they are considered frail patients. In addition, many flares of the underlying disease are reported after routine vaccinations. To date, the vaccination rate in these two populations is suboptimal. According to the latest guidelines, targeted interventions are needed, such as strengthening the network of vaccination activities. Our project aimed to propose a pilot network for carrying out the recommended vaccinations in frail patients. Methods: The Allergy and Immunology Center of the Mauriziano Hospital in Turin, Italy started the "Maurivax" project, a facilitated pathway for frail patients to administer the recommended vaccinations in the setting of a dedicated structure where they could be properly followed up. Results: From June 2022 to February 2023, 49 patients underwent a vaccination consultation: 45 of them (91.8%) were subsequently vaccinated. Among these, 36 subjects (80%) were affected by an active AD and were already in treatment with immunosuppressive therapy or about to start it. Seven patients (15.5%) had a confirmed diagnosis of PID or showed a clinical presentation that was highly suggestive of that condition. Overall, twenty-seven patients (60%) showed a high-grade immunosuppression and six (13.3%) had a low-grade immunosuppression. No patients had a disease flare within 30 days from vaccination and no severe reactions after vaccination was observed. Conclusions: Adherence and vaccination safety at our immunology hospital vaccine clinic dedicated to patients with ADs and PIDs were high. We propose an effective model for managing vaccinations in frail patients in a specialist hospital setting.

Immunogenicity of lipid nanoparticles and its impact on the efficacy of mRNA vaccines and therapeutics

Several studies have utilized a lipid nanoparticle delivery system to enhance the effectiveness of mRNA therapeutics and vaccines. However, these nanoparticles are recognized as foreign materials by the body and stimulate innate immunity, which in turn impacts adaptive immunity. Therefore, it is crucial to understand the specific type of innate immune response triggered by lipid nanoparticles. This article provides an overview of the immunological response in the body, explores how lipid nanoparticles activate the innate immune system, and examines the adverse effects and immunogenicity-related development pathways associated with these nanoparticles. Finally, we highlight and explore strategies for regulating the immunogenicity of lipid nanoparticles.

Human LINE-1 retrotransposons: impacts on the genome and regulation by host factors

Genome sequencing revealed that nearly half of the human genome is comprised of transposable elements. Although most of these elements have been rendered inactive due to mutations, full-length intact long interspersed element-1 (LINE-1 or L1) copies retain the ability to mobilize through RNA intermediates by a so-called "copy-and-paste" mechanism, termed retrotransposition. L1 is the only known autonomous mobile genetic element in the genome, and its retrotransposition contributes to inter- or intra-individual genetic variation within the human population. However, L1 retrotransposition also poses a threat to genome integrity due to gene disruption and chromosomal instability. Moreover, recent studies suggest that aberrant L1 expression can impact human health by causing diseases such as cancer and chronic inflammation that might lead to autoimmune disorders. To counteract these adverse effects, the host cells have evolved multiple layers of defense mechanisms at the epigenetic, RNA and protein levels. Intriguingly, several host factors have also been reported to facilitate L1 retrotransposition, suggesting that there is competition between negative and positive regulation of L1 by host factors. Here, we summarize the known host proteins that regulate L1 activity at different stages of the replication cycle and discuss how these factors modulate disease-associated phenotypes caused by L1.

Bioinformatics-based analysis of the roles of basement membrane-related gene AGRN in systemic lupus erythematosus and pan-cancer development

Introduction

Systemic lupus erythematosus (SLE) is an autoimmune disease involving many systems and organs, and individuals with SLE exhibit unique cancer risk characteristics. The significance of the basement membrane (BM) in the occurrence and progression of human autoimmune diseases and tumors has been established through research. However, the roles of BM-related genes and their protein expression mechanisms in the pathogenesis of SLE and pan-cancer development has not been elucidated.

Methods

In this study, we applied bioinformatics methods to perform differential expression analysis of BM-related genes in datasets from SLE patients. We utilized LASSO logistic regression, SVM-RFE, and RandomForest to screen for feature genes and construct a diagnosis model for SLE. In order to attain a comprehensive comprehension of the biological functionalities of the feature genes, we conducted GSEA analysis, ROC analysis, and computed levels of immune cell infiltration. Finally, we sourced pan-cancer expression profiles from the TCGA and GTEx databases and performed pan-cancer analysis.

Results

We screened six feature genes (AGRN, PHF13, SPOCK2, TGFBI, COL4A3, and COLQ) to construct an SLE diagnostic model. Immune infiltration analysis showed a significant correlation between AGRN and immune cell functions such as parainflammation and type I IFN response. After further gene expression validation, we finally selected AGRN for pan-cancer analysis. The results showed that AGRN's expression level varied according to distinct tumor types and was closely correlated with some tumor patients' prognosis, immune cell infiltration, and other indicators.

Discussion

In conclusion, BM-related genes play a pivotal role in the pathogenesis of SLE, and AGRN shows immense promise as a target in SLE and the progression of multiple tumors.

Endothelial type I interferon response and brain diseases: identifying STING as a therapeutic target

The endothelium layer lining the inner surface of blood vessels serves relevant physiological functions in all body systems, including the exchanges between blood and extravascular space. However, endothelial cells also participate in innate and adaptive immune response that contribute to the pathophysiology of inflammatory disorders. Type I Interferon (IFN) signaling is an inflammatory response triggered by a variety of pathogens, but it can also be induced by misplaced DNA in the cytosol caused by cell stress or gene mutations. Type I IFN produced by blood leukocytes or by the endothelium itself is well-known to activate the interferon receptor (IFNAR) in endothelial cells. Here, we discuss the induction of type I IFN secretion and signaling in the endothelium, specifically in the brain microvasculature where endothelial cells participate in the tight blood-brain barrier (BBB). This barrier is targeted during neuroinflammatory disorders such as infection, multiple sclerosis, Alzheimer's disease and traumatic brain injury. We focus on type I IFN induction through the cGAS-STING activation pathway in endothelial cells in context of autoinflammatory type I interferonopathies, inflammation and infection. By comparing the pathophysiology of two separate infectious diseases-cerebral malaria induced by Plasmodium infection and COVID-19 caused by SARS-CoV-2 infection-we emphasize the relevance of type I IFN and STING-induced vasculopathy in organ dysfunction. Investigating the role of endothelial cells as active type I IFN producers and responders in disease pathogenesis could lead to new therapeutic targets. Namely, endothelial dysfunction and brain inflammation may be avoided with strategies that target excessive STING activation in endothelial cells.

Molecular characterization of PANoptosis-related genes with features of immune dysregulation in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease. PANoptosis is a novel form of programmed cell death involved in various inflammatory diseases. This study aimed to identify the differentially-expressed PANoptosis-related genes (PRGs) involved in immune dysregulation in SLE. Five key PRGs, including ZBP1, MEFV, LCN2, IFI27, and HSP90AB1, were identified. The prediction model with these 5 key PRGs showed a good diagnostic performance in distinguishing SLE patients from controls. These key PRGs were associated with memory B cells, neutrophils and CD8 + T cells. Besides, these key PRGs were significantly enriched in pathways involving the type I interferon responses and IL-6-JAK-STAT3 signaling. The expression levels of the key PRGs were validated in peripheral blood mononuclear cells (PBMCs) of patients with SLE. Our findings suggest that PANoptosis may be implicated in the immune dysregulation in SLE by regulating the interferons and JAK-STAT signaling pathways in memory B cells, neutrophils and CD8 + T cells.

Pathogenesis of systemic lupus erythematosus: risks, mechanisms and therapeutic targets

Research elucidating the pathogenesis of systemic lupus erythematosus (SLE) has defined two critical families of mediators, type I interferon (IFN-I) and autoantibodies targeting nucleic acids and nucleic acid-binding proteins, as fundamental contributors to the disease. On the fertile background of significant genetic risk, a triggering stimulus, perhaps microbial, induces IFN-I, autoantibody production or most likely both. When innate and adaptive immune system cells are engaged and collaborate in the autoimmune response, clinical SLE can develop. This review describes recent data from genetic analyses of patients with SLE, along with current studies of innate and adaptive immune function that contribute to sustained IFN-I pathway activation, immune activation and autoantibody production, generation of inflammatory mediators and tissue damage. The goal of these studies is to understand disease mechanisms, identify therapeutic targets and stimulate development of therapeutics that can achieve improved outcomes for patients.

Gut microbiota: a newly identified environmental factor in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that predominantly affects women of childbearing age and is characterized by the damage to multiple target organs. The pathogenesis of SLE is complex, and its etiology mainly involves genetic and environmental factors. At present, there is still a lack of effective means to cure SLE. In recent years, growing evidence has shown that gut microbiota, as an environmental factor, triggers autoimmunity through potential mechanisms including translocation and molecular mimicry, leads to immune dysregulation, and contributes to the development of SLE. Dietary intervention, drug therapy, probiotics supplement, fecal microbiome transplantation and other ways to modulate gut microbiota appear to be a potential treatment for SLE. In this review, the dysbiosis of gut microbiota in SLE, potential mechanisms linking gut microbiota and SLE, and immune dysregulation associated with gut microbiota in SLE are summarized.

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.

Stimulator of interferon genes is required for Toll-Like Receptor-8 induced interferon response

The innate immune system is equipped with multiple receptors to detect microbial nucleic acids and induce type I interferon (IFN) to restrict viral replication. When dysregulated these receptor pathways induce inflammation in response to host nucleic acids and promote development and persistence of autoimmune diseases like Systemic Lupus Erythematosus (SLE). IFN production is regulated by the Interferon Regulatory Factor (IRF) transcription factor family of proteins that function downstream of several innate immune receptors such as Toll-like receptors (TLRs) and Stimulator of Interferon Genes (STING). Although both TLRs and STING activate the same downstream molecules, the pathway by which TLRs and STING activate IFN response are thought to be independent. Here we show that STING plays a previously undescribed role in human TLR8 signaling. Stimulation with the TLR8 ligands induced IFN secretion in primary human monocytes, and inhibition of STING reduced IFN secretion from primary monocytes from 8 healthy donors. We demonstrate that TLR8-induced IRF activity was reduced by STING inhibitors. Moreover, TLR8-induced IRF activity was blocked by inhibition or loss of IKKε, but not TBK1. Bulk RNA transcriptomic analysis supported a model where TLR8 induces transcriptional responses associated with SLE that can be downregulated by inhibition of STING. These data demonstrate that STING is required for full TLR8-to-IRF signaling and provide evidence for a new framework of crosstalk between cytosolic and endosomal innate immune receptors, which could be leveraged to treat IFN driven autoimmune diseases.

Background

High levels of type I interferon (IFN) is characteristic of multiple autoimmune diseases, and while TLR8 is associated with autoimmune disease and IFN production, the mechanisms of TLR8-induced IFN production are not fully understood.

Results

STING is phosphorylated following TLR8 signaling, which is selectively required for the IRF arm of TLR8 signaling and for TLR8-induced IFN production in primary human monocytes.

Conclusion

STING plays a previously unappreciated role in TLR8-induced IFN production.

Significance

Nucleic acid-sensing TLRs contribute to development and progression of autoimmune disease including interferonopathies, and we show a novel role for STING in TLR-induced IFN production that could be a therapeutic target.

Interferon and autoantigens: intersection in autoimmunity

Interferon (IFN) is a key component of the innate immune response. For reasons that remain incompletely understood, the IFN system is upregulated in several rheumatic diseases, particularly those that feature autoantibody production, such as SLE, Sjögren's syndrome, myositis and systemic sclerosis. Interestingly, many of the autoantigens targeted in these diseases are components of the IFN system, representing IFN-stimulated genes (ISGs), pattern recognition receptors (PRRs), and modulators of the IFN response. In this review, we describe features of these IFN-linked proteins that may underlie their status as autoantigens. Note is also made of anti-IFN autoantibodies that have been described in immunodeficiency states.

Cytokine-mediated STAT-dependent pathways underpinning human B-cell differentiation and function

B cells are fundamental to host defence against infectious diseases; indeed, the ability of humans to elicit robust antibody responses following exposure to foreign antigens underpins long-lived humoral immunity and serological memory, as well as the success of most currently administered vaccines. However, B cells also have a dark side - they can cause myriad diseases, including autoimmunity, atopy, allergy and malignancy. Thus, it is critical to understand the molecular requirements for generating effective, high-affinity, specific immune responses following natural infection or vaccination, as well as for constraining B-cell function to mitigate B-cell-mediated immune dyscrasias. In this review, we discuss recent developments that have been derived from the identification and detailed analysis of individuals with inborn errors of immunity that disrupt cytokine signalling, resulting in immune dysregulatory conditions. These studies have defined fundamental cytokine/cytokine receptor/signal transducer and activator of transcription (STAT) signalling pathways that are critical for the generation and maintenance of human memory B-cell and plasma cell subsets during host defence, as well as revealed mechanisms of disease pathogenesis causing immune deficiency, autoimmunity and atopy. More importantly, these studies have identified molecules that could be targeted to either enhance humoral immunity in the settings of infection or vaccination, or attenuate humoral immunity that contributes to antibody-mediated autoimmunity or allergy.

Immune tolerance breakdown in inborn errors of immunity: Paving the way to novel therapeutic approaches

Up to 25% of the patients with inborn errors of immunity (IEI) also exhibit immunodysregulatory features. The association of immune dysregulation and immunodeficiency may be explained by different mechanisms. The understanding of mechanisms underlying immune dysregulation in IEI has paved the way for the development of targeted treatments. In this review article, we will summarize the mechanisms of immune tolerance breakdown and the targeted therapeutic approaches to immune dysregulation in IEI.

DNA sensing via the cGAS/STING pathway activates the immunoproteasome and adaptive T-cell immunity

The immunoproteasome is a specialized type of proteasome involved in MHC class I antigen presentation, antiviral adaptive immunity, autoimmunity, and is also part of a broader response to stress. Whether the immunoproteasome is regulated by DNA stress, however, is not known. We here demonstrate that mitochondrial DNA stress upregulates the immunoproteasome and MHC class I antigen presentation pathway via cGAS/STING/type I interferon signaling resulting in cell autonomous activation of CD8⁺ T cells. The cGAS/STING-induced adaptive immune response is also observed in response to genomic DNA and is conserved in epithelial and mesenchymal cells of mice and men. In patients with idiopathic pulmonary fibrosis, chronic activation of the cGAS/STING-induced adaptive immune response in aberrant lung epithelial cells concurs with CD8⁺ T-cell activation in diseased lungs. Genetic depletion of the immunoproteasome and specific immunoproteasome inhibitors counteract DNA stress induced cytotoxic CD8⁺ T-cell activation. Our data thus unravel cytoplasmic DNA sensing via the cGAS/STING pathway as an activator of the immunoproteasome and CD8⁺ T cells. This represents a novel potential pathomechanism for pulmonary fibrosis that opens new therapeutic perspectives.

Optimal Selection of IFN-α-Inducible Genes to Determine Type I Interferon Signature Improves the Diagnosis of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies specific to self-molecules in the nucleus, cytoplasm, and cell surface. The diversity of serologic and clinical manifestations observed in SLE patients challenges the development of diagnostics and tools for monitoring disease activity. Elevated type I interferon signature (IFN- I) in SLE leads to dysregulation of innate and adaptive immune function, resulting in autoantibodies production. The most common method to determine IFN-I signature is measuring the gene expression of several IFN-α-inducible genes (IFIGs) in blood samples and calculating a score. Optimal selection of IFIGs improves the sensitivity, specificity, and accuracy of the diagnosis of SLE. We describe the mechanisms of the immunopathogenesis of IFN-I signature (IFNα production) and its clinical consequences in SLE. In addition, we explore the association between IFN-I signature, the presence of autoantibodies, disease activity, medical therapy, and ethnicity. We discuss the presence of IFN-I signature in some patients with other autoimmune diseases, including rheumatoid arthritis, systemic and multiple sclerosis, Sjogren’s syndrome, and dermatomyositis. Prospective studies are required to assess the role of IFIG and the best combination of IFIGs to monitor SLE disease activity and drug treatments.

Interferon-α2a induces CD4+ T cell apoptosis and suppresses Th1/Th17 responses via upregulating IRF1-mediated PDL1 expression in dendritic cells from Behcet's uveitis

Recombinant interferon-α2a (IFNα2a) has been widely used in the treatment of Behcet's uveitis (BU). However, the mechanism underlying its effects remains poorly understood. In this study, we investigated its effect on dendritic cells (DCs) and CD4⁺ T cells, which are essential for the development of BU. Our results showed that the expression of PDL1 and IRF1 was significantly decreased in DCs from active BU patients, and IFNα2a could significantly upregulate PDL1 expression in an IRF1-dependent manner. IFNα2a-treated DCs induced CD4⁺ T cells apoptosis and inhibited the Th1/Th17 immune response in association with reduced secretion of IFN-γ and IL-17. We also found that IFNα2a promoted Th1 cell differentiation and IL-10 secretion by CD4⁺ T cells. Finally, a comparison of patients before and after IFNα2a therapy revealed that the frequencies of Th1/Th17 cells significantly decreased in association with remission of uveitis after IFNα2a therapy. Collectively, these results show that IFNα2a could exert its effects by modulating the function of DCs and CD4⁺ T cells in BU.

The role of non-coding RNA in lupus nephritis

Systemic lupus erythematosus (SLE) is a common autoimmune disease with multiple manifestations. The renal implication, also called lupus nephritis (LN) is the most regular type of complication and results in adverse outcomes. Multiple studies revealed the importance of non-coding RNA in diseases, likewise observed in nephropathies, particularly LN. Long-non-coding RNA (lncRNA) is a group of RNA that are more than 200 nucleotides in length. And in circular RNA (circRNA), the head and tail of RNA are connected by a 3' → 5' phosphodiester bond. Both two types of non-coding RNA play important roles in LN pathogenesis through the competitive endogenous RNA (ceRNA) effect. LncRNAs and circRNAs can sponge miRNAs and consequently act on downstream signaling pathways, which are capable to influence various aspects of LN, including cell proliferation, inflammation, and oxidative stress. And lncRNAs and circRNAs have the potential to act as biomarkers to diagnose LN and distinguish whether SLE patients with LN or not. In the future, lncRNAs and circRNAs may be accessible therapeutic targets.

The critical importance of epigenetics in autoimmune-related skin diseases

Autoimmune-related skin diseases are a group of disorders with diverse etiology and pathophysiology involved in autoimmunity. Genetics and environmental factors may contribute to the development of these autoimmune disorders. Although the etiology and pathogenesis of these disorders are poorly understood, environmental variables that induce aberrant epigenetic regulations may provide some insights. Epigenetics is the study of heritable mechanisms that regulate gene expression without changing DNA sequences. The most important epigenetic mechanisms are DNA methylation, histone modification, and noncoding RNAs. In this review, we discuss the most recent findings regarding the function of epigenetic mechanisms in autoimmune-related skin disorders, including systemic lupus erythematosus, bullous skin diseases, psoriasis, and systemic sclerosis. These findings will expand our understanding and highlight the possible clinical applications of precision epigenetics approaches.

Discussion on the common controversies of Helicobacter pylori infection

BACKGROUND

Helicobacter pylori ( H. pylori ) can persistently colonize on the gastric mucosa after infection and cause gastritis, atrophy, metaplasia, and even gastric cancer (GC).

METHODS

Therefore, the detection and eradication of H. pylori are the prerequisite.

RESULTS

Clinically, there are some controversial issues, such as why H. pylori infection is persistent, why it translocases along with the lesser curvature of the stomach, why there is oxyntic antralization, what the immunological characteristic of gastric chronic inflammation caused by H. pylori is, whether H. pylori infection is associated with extra-gastric diseases, whether chronic atrophic gastritis (CAG) is reversible, and what the potential problems are after H. pylori eradication. What are the possible answers?

CONCLUSION

In the review, we will discuss these issues from the attachment to eradication in detail.

STAT2/Caspase3 in the diagnosis and treatment of psoriasis

BACKGROUND

Psoriasis is a classic chronic recurrent inflammatory skin disease characterized by skin inflammation and abnormal biological behaviour of keratinocytes. Although Signal Transducer And Activator Of Transcription 2 (STAT2) was found to play an important role in the Janus kinase (JAK)-STAT signalling pathway and contribute to the pathogenesis of psoriasis, its exact role in psoriasis remains unclear.

METHODS

Using bioinformatics analysis, we identified the key pathways that significantly impacted psoriatic lesions. After identifying the critical molecule gene differentially expressed in multiple public databases using the Kyoto Encyclopaedia of Genes and Genomes (KEGG) enrichment analysis, clinical samples were collected to validate the gene's significance. Its functions and underlying mechanism were also investigated in vitro. Lastly, we evaluated the diagnostic and therapeutic power of the target gene using the receiver operating characteristic curve (ROC), and gene association was assessed using Spearman correlation.

RESULTS

A significant correlation was found between cysteine-aspartic acid protease3 (Caspase3) and STAT2, and functional enrichment analysis revealed that they were both significantly up-regulated in psoriatic skin lesions compared to non-lesional tissues. Functional analysis revealed that Caspase3 functioned downstream of STAT2 in psoriasis. Lastly, we found that Caspase3 and STAT2 could be potential biomarkers for diagnosing and treating psoriasis.

CONCLUSIONS

In summary, STAT2 overexpression contributes to psoriasis progression by regulating Capase3 phosphorylation to induce excessive apoptosis of keratinocytes. Meanwhile, STAT2 and Capase3 were identified as promising biomarkers for the diagnosis and treatment of psoriasis and could be used for individualized treatments.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Central Role of Macrophages and Nucleic Acid Release in Myasthenia Gravis Thymus

OBJECTIVE

Myasthenia gravis (MG) is a neuromuscular disease mediated by antibodies against the acetylcholine receptor (AChR). The thymus plays a primary role in AChR-MG and is characterized by a type I interferon (IFN) signature linked to IFN-β. We investigated if AChR-MG was characterized by an IFN-I signature in the blood, and further investigated the chronic thymic IFN-I signature.

METHODS

Serum levels of IFN-β and IFN-α subtypes, and mRNA expression for IFN-I subtypes and IFN-stimulated genes in peripheral mononuclear blood cells (PBMCs) were analyzed. The contribution of endogenous nucleic acids in thymic expression of IFN-I subtypes was investigated in human thymic epithelial cell cultures and the mouse thymus. By immunohistochemistry, thymic CD68⁺ and CD163⁺ macrophages were analyzed in AChR-MG. To investigate the impact of a decrease in thymic macrophages, mice were treated with an anti-CSF1R antibody.

RESULTS

No IFN-I signature was observed in the periphery emphasizing that the IFN-I signature is restricted to the MG thymus. Molecules mimicking endogenous dsDNA signalization (Poly(dA:dT) and 2'3'-cGAMP), or dexamethasone-induced necrotic thymocytes increased IFN-β and α-AChR expression by thymic epithelial cells, and in the mouse thymus. A significant decrease in thymic macrophages was demonstrated in AChR-MG. In mice, a decrease in thymic macrophages led to an increase of necrotic thymocytes associated with IFN-β and α-AChR expression.

INTERPRETATION

These results suggest that the decrease of thymic macrophages in AChR-MG impairs the elimination of apoptotic thymocytes favoring the release of endogenous nucleic acids from necrotic thymocytes. In this inflammatory context, thymic epithelial cells may overexpress IFN-β, which specifically induces α-AChR, resulting in self-sensitization and thymic changes leading to AChR-MG. ANN NEUROL 2023.

Mitochondrial double-stranded RNAs as a pivotal mediator in the pathogenesis of Sjӧgren's syndrome

Sjӧgren's syndrome (SS) is a systemic autoimmune disease that targets the exocrine glands, resulting in impaired saliva and tear secretion. To date, type I interferons (I-IFNs) are increasingly recognized as pivotal mediators in SS, but their endogenous drivers have not been elucidated. Here, we investigate the role of mitochondrial double-stranded RNAs (mt-dsRNAs) in regulating I-IFNs and other glandular phenotypes of SS. We find that mt-dsRNAs are elevated in the saliva and tears of SS patients (n = 73 for saliva and n = 16 for tears) and in salivary glands of non-obese diabetic mice with salivary dysfunction. Using the in-house-developed 3D culture of immortalized human salivary gland cells, we show that stimulation by exogenous dsRNAs increase mt-dsRNAs, activate the innate immune system, trigger I-IFNs, and promote glandular phenotypes. These responses are mediated via the Janus kinase 1 (JAK1)/signal transducer and activator of transcription (STAT) pathway. Indeed, a small chemical inhibitor of JAK1 attenuates mtRNA elevation and immune activation. We further show that muscarinic receptor ligand acetylcholine ameliorates autoimmune characteristics by preventing mt-dsRNA-mediated immune activation. Last, direct suppression of mt-dsRNAs reverses the glandular phenotypes of SS. Altogether, our study underscores the significance of mt-dsRNA upregulation in the pathogenesis of SS and suggests mt-dsRNAs as propagators of a pseudo-viral signal in the SS target tissue.

Treatment-resistant idiopathic multicentric Castleman disease with thrombocytopenia, anasarca, fever, reticulin fibrosis, renal dysfunction, and organomegaly managed with Janus kinase inhibitors: A case report

RATIONALE

Thrombocytopenia, anasarca, fever, reticulin fibrosis, renal dysfunction, and organomegaly (TAFRO) syndrome are nonmalignant but life-threatening systemic inflammatory disorders. However, many patients are refractory to treatment, resulting in significant morbidity and mortality. Additionally, established treatment options are unavailable. Therefore, we present 2 cases of adults with the iMCD-TAFRO syndrome refractory to initial treatment but responded to Janus kinase (JAK) inhibitors with ruxolitinib. The report reveals that these rare adult cases of the refractory and treatment-resistant iMCD-TAFRO syndrome can be treated using JAK inhibitors.

PATIENT CONCERNS

Case 1 is a 36-year-old previously healthy male patient who presented with fever and general fatigue for 2 weeks. Case 2 is a 42-year-old previously healthy female patient who presented with fever and general fatigue.

DIAGNOSIS

The diagnosis met the 2015 criteria for TAFRO syndrome, as determined by All Japan TAFRO Syndrome Research Group in the Research Program for Intractable Disease by the Ministry of Health, Labor and Welfare (MHLW) Japan.

INTERVENTIONS

Treatment with tocilizumab and several immunosuppressants were ineffective. So, we performed ruxolitinib.

OUTCOMES

Each patient received ruxolitinib, the general condition improved, and CRP levels decreased.

LESSONS

These cases showed that ruxolitinib was effective for treatment-resistant/ refractory TAFRO syndrome. Further prospective studies are needed on using ruxolitinib with a small number of cases.

Advances in lupus therapeutics: Achieving sustained control of the type I interferon pathway

Achieving sustained control of disease activity in patients with systemic lupus erythematosus has been impeded by the complexity of its immunopathogenesis as well its clinical heterogeneity. In spite of these challenges, gains in understanding disease mechanisms have identified immune targets that are currently under study in trials of candidate therapeutics. Defining the type I interferon (IFN-I) pathway and autoantibodies specific for nucleic acid binding proteins as core pathogenic mediators allows an analysis of approaches that could control production of those mediators and improve patient outcomes. This review describes therapeutic targets and agents that could achieve control of the IFN-I pathway. Toll-like receptor 7, involved in IFN-I production and differentiation of B cells, and long-lived plasma cells, the producers of autoantibodies specific for RNA-binding proteins, components of the immune complex drivers of IFN-I, are particularly attractive therapeutic targets.

The role of type I IFN in autoimmune and autoinflammatory diseases with CNS involvement

Type I interferons (IFNs) are major mediators of innate immunity, with well-known antiviral, antiproliferative, and immunomodulatory properties. A growing body of evidence suggests the involvement of type I IFNs in the pathogenesis of central nervous system (CNS) manifestations in the setting of chronic autoimmune and autoinflammatory disorders, while IFN-β has been for years, a well-established therapeutic modality for multiple sclerosis (MS). In the present review, we summarize the current evidence on the mechanisms of type I IFN production by CNS cellular populations as well as its local effects on the CNS. Additionally, the beneficial effects of IFN-β in the pathophysiology of MS are discussed, along with the contributory role of type I IFNs in the pathogenesis of neuropsychiatric lupus erythematosus and type I interferonopathies.

Chronic activation of pDCs in autoimmunity is linked to dysregulated ER stress and metabolic responses

Plasmacytoid dendritic cells (pDCs) chronically produce type I interferon (IFN-I) in autoimmune diseases, including systemic sclerosis (SSc) and systemic lupus erythematosus (SLE). We report that the IRE1α-XBP1 branch of the unfolded protein response (UPR) inhibits IFN-α production by TLR7- or TLR9-activated pDCs. In SSc patients, UPR gene expression was reduced in pDCs, which inversely correlated with IFN-I-stimulated gene expression. CXCL4, a chemokine highly secreted in SSc patients, downregulated IRE1α-XBP1-controlled genes and promoted IFN-α production by pDCs. Mechanistically, IRE1α-XBP1 activation rewired glycolysis to serine biosynthesis by inducing phosphoglycerate dehydrogenase (PHGDH) expression. This process reduced pyruvate access to the tricarboxylic acid (TCA) cycle and blunted mitochondrial ATP generation, which are essential for pDC IFN-I responses. Notably, PHGDH expression was reduced in pDCs from patients with SSc and SLE, and pharmacological blockade of TCA cycle reactions inhibited IFN-I responses in pDCs from these patients. Hence, modulating the IRE1α-XBP1-PHGDH axis may represent a hitherto unexplored strategy for alleviating chronic pDC activation in autoimmune disorders.

Nucleic acid-sensing toll-like receptors: Important players in Sjögren’s syndrome

Sjögren’s syndrome (SS) is a chronic systemic autoimmune disease that affects the salivary and lacrimal glands, as well as other organ systems like the lungs, kidneys and nervous system. SS can occur alone or in combination with another autoimmune disease, such as systemic lupus erythematosus (SLE) or rheumatoid arthritis. The etiology of SS is unknown but recent studies have revealed the implication of the activation of innate immune receptors, including Toll-like receptors (TLRs), mainly through the detection of endogenous nucleic acids, in the pathogenesis of systemic autoimmune diseases. Studies on SS mouse models suggest that TLRs and especially TLR7 that detects single-stranded RNA of microbial or endogenous origin can drive the development of SS and findings in SS patients corroborate those in mouse models. In this review, we will give an overview of the function and signaling of nucleic acid-sensing TLRs, the interplay of TLR7 with TLR8 and TLR9 in the context of autoimmunity, summarize the evidence for the critical role of TLR7 in the pathogenesis of SS and present a possible connection between SARS-CoV-2 and SS.

Type I Interferon Receptor Subunit 1 Deletion Attenuates Experimental Abdominal Aortic Aneurysm Formation

Objective: Type I interferon receptor signaling contributes to several autoimmune and vascular diseases such as lupus, atherosclerosis and stroke. The purpose of this study was to assess the influence of type I interferon receptor deficiency on the formation and progression of experimental abdominal aortic aneurysms (AAAs). Methods: AAAs were induced in type I interferon receptor subunit 1 (IFNAR1)-deficient and wild type control male mice via intra-infrarenal aortic infusion of porcine pancreatic elastase. Immunostaining for IFNAR1 was evaluated in experimental and clinical aneurysmal abdominal aortae. The initiation and progression of experimental AAAs were assessed via ultrasound imaging prior to (day 0) and days 3, 7 and 14 following elastase infusion. Aneurysmal histopathology was analyzed at sacrifice. Results: Increased aortic medial and adventitial IFNAR1 expression was present in both clinical AAAs harvested at surgery and experimental AAAs. Following AAA induction, wild type mice experienced progressive, time-dependent infrarenal aortic enlargement. This progression was substantially attenuated in IFNAR1-deficient mice. On histological analyses, medial elastin degradation, smooth muscle cell depletion, leukocyte accumulation and neoangiogenesis were markedly diminished in IFNAR1-deficient mice in comparison to wild type mice. Conclusion: IFNAR1 deficiency limited experimental AAA progression in response to intra-aortic elastase infusion. Combined with clinical observations, these results suggest an important role for IFNAR1 activity in AAA pathogenesis.

Blood concentrations of per- and polyfluoroalkyl substances are associated with autoimmune-like effects in American alligators from Wilmington, North Carolina

Surface and groundwater of the Cape Fear River basin in central and coastal North Carolina is contaminated with high levels of per- and polyfluoroalkyl substances (PFAS). Elevated levels of PFAS have also been found in blood of fish and wildlife from the Cape Fear River, and in the blood of human populations reliant on contaminated well or surface water from the Cape Fear River basin as a source of drinking water. While the public and environmental health impacts of long-term PFAS exposures are poorly understood, elevated blood concentrations of some PFAS are linked with immunotoxicity and increased incidence of some chronic autoimmune diseases in human populations. The goal of this One Environmental Health study was to evaluate PFAS exposure and biomarkers related to immune health in populations of American alligators (Alligator mississippiensis), a protected and predictive sentinel species of adverse effects caused by persistent toxic pollutants. We found that serum PFAS concentrations in alligator populations from the Cape Fear River were increased compared to a reference population of alligators from the adjoining Lumber River basin. The elevated serum PFAS concentrations in the Cape Fear River alligators were associated with increased innate immune activities, and autoimmune-like phenotypes in this population. In addition to evidence of significantly higher double stranded-DNA binding autoantibodies in adult Cape Fear River alligators, our qRT-PCR analysis found remarkably high induction of Interferon-α signature genes implicated in the pathology of human autoimmune disease. We interpret the association of increased PFAS exposure with disrupted immune functions to suggest that PFAS broadly alters immune activities resulting in autoimmune-like pathology in American alligators. This work substantiates and extends evidence from experimental models and human epidemiology studies showing that some PFAS are immune toxicants.