Type I Interferons in Autoimmunity

Intermittent hypoxia exacerbates anxiety in high-fat diet-induced diabetic mice by inhibiting TREM2-regulated IFNAR1 signaling

BACKGROUND

Type 2 diabetes mellitus (T2DM) and obstructive sleep apnea (OSA) are mutual risk factors, with both conditions inducing cognitive impairment and anxiety. However, whether OSA exacerbates cognitive impairment and anxiety in patients with T2DM remains unclear. Moreover, TREM2 upregulation has been suggested to play a protective role in attenuating microglia activation and improving synaptic function in T2DM mice. The aim of this study was to explore the regulatory mechanisms of TREM2 and the cognitive and anxiety-like behavioral changes in mice with OSA combined with T2DM.

METHODS

A T2DM with OSA model was developed by treating mice with a 60% kcal high-fat diet (HFD) combined with intermittent hypoxia (IH). Spatial learning memory capacity and anxiety in mice were investigated. Neuronal damage in the brain was determined by the quantity of synapses density, the number and morphology of brain microglia, and pro-inflammatory factors. For mechanism exploration, an in vitro model of T2DM combined with OSA was generated by co-treating microglia with high glucose (HG) and IH. Regulation of TREM2 on IFNAR1-STAT1 pathway was determined by RNA sequencing and qRT-PCR.

RESULTS

Our results showed that HFD mice exhibited significant cognitive dysfunction and anxiety-like behavior, accompanied by significant synaptic loss. Furthermore, significant activation of brain microglia and enhanced microglial phagocytosis of synapses were observed. Moreover, IH was found to significantly aggravate anxiety in the HFD mice. The mechanism of HG treatment may potentially involve the promotion of TREM2 upregulation, which in turn attenuates the proinflammatory microglia by inhibiting the IFNAR1-STAT1 pathway. Conversely, a significant reduction in TREM2 in IH-co-treated HFD mice and HG-treated microglia resulted in the further activation of the IFNAR1-STAT1 pathway and consequently increased proinflammatory microglial activation.

CONCLUSIONS

HFD upregulated the IFNAR1-STAT1 pathway and induced proinflammatory microglia, leading to synaptic damage and causing anxiety and cognitive deficits. The upregulated TREM2 inT2DM mice brain exerted a negative regulation of the IFNAR1-STAT1 pathway. Mice with T2DM combined with OSA exacerbated anxiety via the downregulation of TREM2, causing heightened IFNAR1-STAT1 pathway activation and consequently increasing proinflammatory microglia.

Multi-omics analysis uncovered systemic lupus erythematosus and COVID-19 crosstalk

BACKGROUND

Studies have highlighted a possible crosstalk between the pathogeneses of COVID-19 and systemic lupus erythematosus (SLE); however, the interactive mechanisms remain unclear. We aimed to elucidate the impact of COVID-19 on SLE using clinical information and the underlying mechanisms of both diseases.

METHODS

RNA-seq datasets were used to identify shared hub gene signatures between COVID-19 and SLE, while genome-wide association study datasets were used to delineate the interaction mechanisms of the key signaling pathways. Finally, single-cell RNA-seq datasets were used to determine the primary target cells expressing the shared hub genes and key signaling pathways.

RESULTS

COVID-19 may affect patients with SLE through hematologic involvement and exacerbated inflammatory responses. We identified 14 shared hub genes between COVID-19 and SLE that were significantly associated with interferon (IFN)-I/II. We also screened and obtained four core transcription factors related to these hub genes, confirming the regulatory role of the IFN-I/II-mediated Janus kinase/signal transducers and activators of transcription (JAK-STAT) signaling pathway on these hub genes. Further, SLE and COVID-19 can interact via IFN-I/II and IFN-I/II receptors, promoting the levels of monokines, including interleukin (IL)-6/10, tumor necrosis factor-α, and IFN-γ, and elevating the incidence rate and risk of cytokine release syndrome. Therefore, in SLE and COVID-19, both hub genes and core TFs are enriched within monocytes/macrophages.

CONCLUSIONS

The interaction between SLE and COVID-19 promotes the activation of the IFN-I/II-triggered JAK-STAT signaling pathway in monocytes/macrophages. These findings provide a new direction and rationale for diagnosing and treating patients with SLE-COVID-19 comorbidity.

LTN1 promotes RLR degradation to inhibit immune response to RNA virus through the ESCRT pathway

The excessive activation of immune responses will trigger autoimmune diseases or inflammatory injury. The endosomal sorting complexes required for transport (ESCRT) system can capture and mediate ubiquitinated protein degradation, which timely terminates signaling pathway hyperactivation. However, whether the ESCRT system participates in regulating RIGI-like receptor (RLR)-mediated antiviral responses remains unknown. In this study, we show that LTN1/listerin, a major component of RQC, can recruit E3 ubiquitin ligase TRIM27 to trigger K63-linked polyubiquitination of RIGI and IFIH1/MDA5. This K63-linked polyubiquitination facilitates the sorting and degradation of RIGI and IFIH1 proteins through the ESCRT-dependent pathway. Concordantly, LTN1 deficiency enhances the innate antiviral response to infection with RNA viruses. Thus, our work uncovers a new mechanism for RIGI and IFIH1 degradation and identifies the role of LTN1 in negatively regulating RLR-mediated antiviral innate immunity, which may provide new targets for the intervention of viral infection.Abbreviation: 5'-pppRNA: 5' triphosphate double stranded RNA; ATG5: autophagy related 5; ATG7: autophagy related 7; BafA1: bafilomycin A1; ESCRT: endosomal sorting complexes required for transport; CHX: cycloheximide; IFIH1/MDA5: interferon induced with helicase C domain 1; IFN: interferon; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; RIGI: RNA sensor RIG-I; RLR: RIGI-like receptors; RQC: ribosome-associated protein quality control; SeV: Sendai virus; TRIM27: tripartite motif-containing 27; VSV: vesicular stomatitis virus; VPS4: vacuolar protein sorting 4.

Cloning and functional characterization of novel human neutralizing anti-interferon-alpha and anti-interferon-beta antibodies

Type I interferons (IFNs) play a pivotal role in immune response modulation, yet dysregulation is implicated in various disorders. Therefore, it is crucial to develop tools that facilitate the understanding of their mechanism of action and enable the development of more effective anti-IFN therapeutic strategies. In this study, we isolated, cloned, and characterized anti-IFN-α and anti-IFN-β antibodies (Abs) from peripheral blood mononuclear cells of individuals treated with IFN-α or IFN-β, harboring confirmed neutralizing Abs. Clones AH07856 and AH07857 were identified as neutralizing anti-IFN-α-specific with inhibition against IFN-α2a, -α2b, and -αK subtypes. Clones AH07859 and AH07866 were identified as neutralizing anti-IFN-β1a-specific signaling, and able to block Lipopolysaccharide or S100 calcium binding protein A14-induced IFN-β signaling effects. Cloned Abs bind rhesus but not murine IFNs. The specificity of inhibition between IFN-α and IFN-β suggests potential for diverse research and clinical applications.

Insight into the role of IRF7 in skin and connective tissue diseases

Interferons (IFNs) are signalling proteins primarily involved in initiating innate immune responses against pathogens and promoting the maturation of immune cells. Interferon Regulatory Factor 7 (IRF7) plays a pivotal role in the IFNs signalling pathway. The activation process of IRF7 is incited by exogenous or abnormal nucleic acids, which is followed by the identification via pattern recognition receptors (PRRs) and the ensuing signalling cascades. Upon activation, IRF7 modulates the expression of both IFNs and inflammatory gene regulation. As a multifunctional transcription factor, IRF7 is mainly expressed in immune cells, yet its presence is also detected in keratinocytes, fibroblasts, and various dermal cell types. In these cells, IRF7 is critical for skin immunity, inflammation, and fibrosis. IRF7 dysregulation may lead to autoimmune and inflammatory skin conditions, including systemic scleroderma (SSc), systemic lupus erythematosus (SLE), Atopic dermatitis (AD) and Psoriasis. This comprehensive review aims to extensively elucidate the role of IRF7 and its signalling pathways in immune cells and keratinocytes, highlighting its significance in skin-related and connective tissue diseases.

PANoptosis Features, a Humanized NSG Murine Model of Sjogren's Syndrome

Sjogren's syndrome (SS) is a complex systemic autoimmune disease. This study aims to elucidate a humanized NOD-PrkdcscidIl2rgem1/Smoc (NSG) murine model to better clarify the pathogenesis of SS. NSG female mice were adoptively transferred with 10 million peripheral blood mononuclear cells (PBMCs) through the tail vein from healthy controls (HCs), primary Sjogren's syndrome (pSS), and systemic lupus erythematosus (SLE) patients on D0. The mice were subcutaneously injected with C57/B6j submandibular gland (SG) protein or phosphate-buffered saline on D3, D17 and D31, respectively. NSG mice were successfully transplanted with human PBMCs. Compared with NSG-HC group, NSG-pSS and NSG-SLE mice exhibited a large number of lymphocytes infiltration in the SG, decreased salivary flow rate, lung involvement, decreased expression of genes related to salivary secretion, and the production of autoantibodies. Type I interferon-related genes were increased in the SG of NSG-pSS and NSG-SLE mice. The ratio of BAX/BCL2, BAX, cleaved caspase3, and TUNEL staining were increased in the SG of NSG-pSS and NSG-SLE mice. The expressions of p-MLKL and p-RIPK3 were increased in the SG of NSG-pSS and NSG-SLE mice. Increased expression of type I interferon-related genes, PANoptosis (apoptosis and necroptosis) were identified in the SG of this typical humanized NSG murine model of SS.

Weighted Gene Co-expression Network Analysis and Machine Learning Validation for Identifying Major Genes Related to Sjogren's Syndrome

Sjogren's syndrome (SS) is an autoimmune disorder characterized by dry mouth and dry eyes. Its pathogenic mechanism is currently unclear. This study aims to integrate weighted gene co-expression network analysis (WGCNA) and machine learning to identify key genes associated with SS. We downloaded 3 publicly available datasets from the GEO database comprising the gene expression data of 231 SS and 78 control cases, including GSE84844, GSE48378 and GSE51092, and carried out WGCNA to elucidate differences in the abundant genes. Candidate biomarkers for SS were then identified using a LASSO regression model. Totally 6 machine-learning models were subsequently utilized for validating the biological significance of major genes according to their expression. Finally, immune cell infiltration of the SS tissue was assessed using the CIBERSORT algorithm. A weighted gene co-expression network was built to divide genes into 10 modules. Among them, blue and red modules were most closely associated with SS, and showed significant enrichment in type I interferon signaling, cellular response to type I interferon and response to virus, etc. Combined machine learning identified 5 hub genes, including OAS1, EIF2AK2, IFITM3, TOP2A and STAT1. Immune cell infiltration analysis showed that SS was associated with CD8+ T cell, CD4+ T cell, gamma delta T cell, NK cell and dendritic cell activation. WGCNA was combined with machine learning to uncover genes that may be involved in SS pathogenesis, which can be utilized for developing SS biomarkers and appropriate therapeutic targets.

Bi-directional regulation of type I interferon signaling by heme oxygenase-1

Moderate activation of IFN-I contributes to the body's immune response, but its abnormal expression, stimulated by oxidative stress or other factors causes pathological damage. Heme oxygenase-1 (HO-1), induced by stress stimuli in the body, exerts a central role in cellular protection. Here we showed that HO-1 could promote IFN-1 under Spring Viremia of Carp virus (SVCV) infection and concomitantly attenuate the replication of SVCV. Further characterization of truncated mutants of HO-1 confirmed that intact HO-1 was essential for its antiviral function via IFN-I. Importantly, HO-1 inhibited the IFN-I signal by degrading the IRF3/7 through the autophagy pathway when it was triggered by H2O2 treatment. The iron ion-binding site (His28) was critical for HO-1 to degrade IRF3/7. HO-1 degradation of IRF3/7 is conserved in fish and mammals. Collectively, HO-1 regulates IFN-I positively under viral infection and negatively under oxidative stress, elucidating a mechanism by which HO-1 regulates IFN-I signaling in bi-directions.

Inflammatory cytokines and their potential role in Sjogren's syndrome risk: insights from a mendelian randomization study

AIM

This study aimed to investigate the causal impact of inflammatory cytokines on Sjogren's Syndrome (SS) and to identify potential biomarkers for SS clinical management using Mendelian Randomization (MR).

MATERIALS AND METHODS

Leveraging GWAS summary data of inflammatory cytokines and SS, we executed the first two-sample MR analysis. Genetic variants from prior GWASs associated with circulating inflammatory cytokines served as instrumental variables (IVs). Data regarding cytokines were analyzed using the Olink Target-96 Inflammation panel, synthesizing data from 14,824 participants. GWAS summary statistics for SS were procured from the UK Biobank, focusing on samples of European ancestry. To discern the causal relationship between inflammatory cytokines and SS, several MR methodologies, including inverse variance weighted (IVW) and MR-Egger regression, were applied.

RESULTS

After rigorous IV quality control, 91 cytokines were incorporated into the MR analysis. The IVW analysis identified 8 cytokines with a positive association to SS: Axin-1 (OR 2.56, 95% CI 1.07-6.10), T-cell surface glycoprotein CD5 (OR 1.81, 95% CI 1.08-3.02), CUDP1 (OR 1.61, 95% CI 1.00-2.58), CXCL10 (OR 1.92, 95% CI 1.25-2.95), IL-4 (OR 2.18, 95% CI 1.22-3.91), IL-7 (OR 2.35, 95% CI 1.27-4.33), MCP-2 (OR 1.27, 95% CI 1.05-1.54), and TNFRSF9 (OR 1.83, 95% CI 1.03-3.24), suggesting their potential in increasing SS risk.

CONCLUSION

Our study conducted through MR, identified various inflammatory cytokines associated with SS risk, validating some previous research results and offering some new potential biomarkers for SS. However, these findings necessitate further research for validation and exploration of their precise role in the onset and progression of SS.

Role of neutrophils in cutaneous lupus erythematosus

There are various types of cutaneous lupus erythematosus (CLE), either with or without the association of systemic lupus erythematosus (SLE). In some of the subtypes of cutaneous lupus, histopathology reveals neutrophil infiltration in the lesional skin; however, the significance of neutrophils in CLE is not yet fully elucidated. Recent studies have shown that neutrophil extracellular traps (NETs) formation by activated neutrophils is observed in several types of CLE, including lupus panniculitis, subacute lupus erythematosus, and acute lupus erythematosus, although the number of reports is small. Excessive NETosis, due to either increased NETs formation or defective clearance of NETs, may play a role in the induction of autoimmunity and autoantibody production in SLE, as well as endothelial damage, thrombus formation, and vascular damage in the lesional skin. CLE is an excessive interferon-driven autoimmune disease. Plasmacytoid dendritic cells are located in lupus erythematosus skin and contribute to the etiology of skin lesions as a main producing cell of type I interferon. Neutrophils, monocytes, and keratinocytes also produce type I interferon via several triggers. Neutrophils play an important role in the innate immune response in SLE. In this review, several types of CLE with neutrophil infiltration, as well as the role of neutrophils are discussed.

Construction of a Multi-Indicator Model for Abscess Prediction in Granulomatous Lobular Mastitis Using Inflammatory Indicators

Background

Granulomatous lobular mastitis (GLM) is a chronic inflammatory breast disease, and abscess formation is a common complication of GLM. The process of abscess formation is accompanied by changes in multiple inflammatory markers. The present study aimed to construct a diagnosis model for the early of GLM abscess formation based on multiple inflammatory parameters.

Methods

Based on the presence or absence of abscess formation on breast magnetic resonance imaging (MRI), 126 patients with GLM were categorised into an abscess group (85 patients) and a non-abscess group (41 patients). Demographic characteristics and the related laboratory results for the 9 inflammatory markers were collected. Logistics univariate analysis and collinearity test were used for selecting independent variables. A regression model to predict abscess formation was constructed using Logistics multivariate analysis.

Results

The univariate and multivariate analysis showed that the N, ESR, IL-4, IL-10 and INF-α were independent diagnostic factors of abscess formation in GLM (P<0. 05). The nomogram was drawn on the basis of the logistics regression model. The area under the curve (AUC) of the model was 0.890, which was significantly better than that of a single indicator and the sensitivity and specificity of the model were high (81.2% and 85.40%, respectively). These results predicted by the model were highly consistent with the actual diagnostic results. The results of this calibration curve indicated that the model had a good value and stability in predicting abscess formation in GLM. The decision curve analysis (DCA) demonstrated a satisfactory positive net benefit of the model.

Conclusion

A predictive model for abscess formation in GLM based on inflammatory markers was constructed in our study, which may provide a new strategy for early diagnosis and treatment of the abscess stage of GLM.

The crucial regulatory role of type I interferon in inflammatory diseases

Type I interferon (IFN-I) plays crucial roles in the regulation of inflammation and it is associated with various inflammatory diseases including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and periodontitis, impacting people's health and quality of life. It is well-established that IFN-Is affect immune responses and inflammatory factors by regulating some signaling. However, currently, there is no comprehensive overview of the crucial regulatory role of IFN-I in distinctive pathways as well as associated inflammatory diseases. This review aims to provide a narrative of the involvement of IFN-I in different signaling pathways, mainly mediating the related key factors with specific targets in the pathways and signaling cascades to influence the progression of inflammatory diseases. As such, we suggested that IFN-Is induce inflammatory regulation through the stimulation of certain factors in signaling pathways, which displays possible efficient treatment methods and provides a reference for the precise control of inflammatory diseases.

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.

Patients with dermatomyositis shared partially similar transcriptome signature with COVID-19 infection

Dermatomyositis (DM) is an autoimmune disease that primarily affects the skin and skeletal muscle. Virus infection and type I interferon-related signaling pathways play an important role in the pathogenesis of dermatomyositis. In this study, we found that the skin of patients with DM and the skin of patients with COVID-19 have similar transcriptional profiles, and identified key genes involved in dermatomyositis based on bioinformatics analysis. These hub-genes might be served as potential biomarkers for the early diagnosis and therapy of DM, including MX1, ISG15, IFIT3, IFIT1, RSAD2, IFIT2, IFI6, XAF1, IRF9, MX2.

Type I Interferons in Autoimmunity: Implications in Clinical Phenotypes and Treatment Response

Type I interferon (IFN-I) is thought to play a role in many systemic autoimmune diseases. IFN-I pathway activation is associated with pathogenic features, including the presence of autoantibodies and clinical phenotypes such as more severe disease with increased disease activity and damage. We will review the role and potential drivers of IFN-I dysregulation in 5 prototypic autoimmune diseases: systemic lupus erythematosus, dermatomyositis, rheumatoid arthritis, primary Sjögren syndrome, and systemic sclerosis. We will also discuss current therapeutic strategies that directly or indirectly target the IFN-I system.

Targeting cyclin-dependent kinases in rheumatoid arthritis and psoriasis - a review of current evidence

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with synovial proliferation and bone erosion, which leads to the structural and functional impairment of the joints. Immune cells, together with synoviocytes, induce a pro-inflammatory environment and novel treatment agents target inflammatory cytokines. Psoriasis is a chronic immune-mediated skin disease, and several cytokines are considered as typical mediators in the progression of the disease, including IL-23, IL-22, and IL-17, among others.

AREA COVERED

In this review, we try to evaluate whether cyclin-dependent kinases (CDK), enzymes that regulate cell cycle and transcription of various genes, could become novel therapeutic targets in RA and psoriasis. We present the main results of in vitro and in vivo studies, as well as scarce clinical reports.

EXPERT OPINION

CDK inhibitors seem promising for treating RA and psoriasis because of their multidirectional effects. CDK inhibitors may affect not only the process of osteoclastogenesis, thereby reducing joint destruction in RA, but also the process of apoptosis of neutrophils and macrophages responsible for the development of inflammation in both RA and psoriasis. However, assessing the efficacy of these drugs in clinical practice requires multi-center, long-term clinical trials evaluating the effectiveness and safety of CDK-blocking therapy in RA and psoriasis.

Key Genes of Immunity Associated with Pterygium and Primary Sjögren's Syndrome

Pterygium and primary Sjögren's Syndrome (pSS) share many similarities in clinical symptoms and ocular pathophysiological changes, but their etiology is unclear. To identify the potential genes and pathways related to immunity, two published datasets, GSE2513 containing pterygium information and GSE176510 containing pSS information, were selected from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) of pterygium or pSS patients compared with healthy control conjunctiva, and the common DEGs between them were analyzed. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were conducted for common DEGs. The protein-protein interaction (PPI) network was constructed using the STRING database to find the hub genes, which were verified in clinical samples. There were 14 co-upregulated DEGs. The GO and KEGG analyses showed that these common DEGs were enriched in pathways correlated with virus infection, antigen processing and presentation, nuclear factor-kappa B (NF-κB) and Th17 cell differentiation. The hub genes (IL1R1, ICAM1, IRAK1, S100A9, and S100A8) were selected by PPI construction. In the era of the COVID-19 epidemic, the relationship between virus infection, vaccination, and the incidence of pSS and pterygium growth deserves more attention.

Five genes as diagnostic biomarkers of dermatomyositis and their correlation with immune cell infiltration

Background

Dermatomyositis (DM) is a rare autoimmune disease characterized by severe muscle dysfunction, and the immune response of the muscles plays an important role in the development of DM. Currently, the diagnosis of DM relies on symptoms, physical examination, and biopsy techniques. Therefore, we used machine learning algorithm to screen key genes, and constructed and verified a diagnostic model composed of 5 key genes. In terms of immunity, The relationship between 5 genes and immune cell infiltration in muscle samples was analyzed. These diagnostic and immune-cell-related genes may contribute to the diagnosis and treatment of DM.

Methods

GSE5370 and GSE128470 datasets were utilised from the Gene Expression Omnibus database as DM test sets. And we also used R software to merge two datasets and to analyze the results of differentially expressed genes (DEGs) and functional correlation analysis. Then, we could detect diagnostic genes adopting least absolute shrinkage and selection operator (LASSO) logistic regression and support vector machine recursive feature elimination (SVM-RFE) analyses. The validity of putative biomarkers was assessed using the GSE1551 dataset, and we confirmed the area under the receiver operating characteristic curve (AUC) values. Finally, CIBERSORT was used to evaluate immune cell infiltration in DM muscles and the correlations between disease-related biomarkers and immune cells.

Results

In this study, a total of 414 DEGs were screened. ISG15, TNFRSF1A, GUSBP11, SERPINB1 and PTMA were identified as potential DM diagnostic biomarkers(AUC > 0.85),and the expressions of 5 genes in DM group were higher than that in healthy group (p < 0.05). Immune cell infiltration analyses indicated that identified DM diagnostic biomarkers may be associated with M1 macrophages, activated NK cells, Tfh cells, resting NK cells and Treg cells.

Conclusion

The study identified that ISG15, TNFRSF1A, GUSBP11, SERPINB1 and PTMA as potential diagnostic biomarkers of DM and these genes were closely correlated with immune cell infiltration.This will contribute to future studies in diagnosis and treatment of DM.

Single cell analysis of docosahexaenoic acid suppression of sequential LPS-induced proinflammatory and interferon-regulated gene expression in the macrophage

Preclinical and clinical studies suggest that consumption of long chain omega-3 polyunsaturated fatty acids (PUFAs) reduces severity of chronic inflammatory and autoimmune diseases. While these ameliorative effects are conventionally associated with downregulated expression of proinflammatory cytokine and chemokine genes, our laboratory has recently identified Type 1 interferon (IFN1)-regulated gene expression to be another key target of omega-3 PUFAs. Here we used single cell RNA sequencing (scRNAseq) to gain new mechanistic perspectives on how the omega-3 PUFA docosahexaenoic acid (DHA) influences TLR4-driven proinflammatory and IFN1-regulated gene expression in a novel self-renewing murine fetal liver-derived macrophage (FLM) model. FLMs were cultured with 25 µM DHA or vehicle for 24 h, treated with modest concentration of LPS (20 ng/ml) for 1 and 4 h, and then subjected to scRNAseq using the 10X Chromium System. At 0 h (i.e., in the absence of LPS), DHA increased expression of genes associated with the NRF2 antioxidant response (e.g. Sqstm1, Hmox1, Chchd10) and metal homeostasis (e.g.Mt1, Mt2, Ftl1, Fth1), both of which are consistent with DHA-induced polarization of FLMs to a more anti-inflammatory phenotype. At 1 h post-LPS treatment, DHA inhibited LPS-induced cholesterol synthesis genes (e.g. Scd1, Scd2, Pmvk, Cyp51, Hmgcs1, and Fdps) which potentially could contribute to interference with TLR4-mediated inflammatory signaling. At 4 h post-LPS treatment, LPS-treated FLMs reflected a more robust inflammatory response including upregulation of proinflammatory cytokine (e.g. Il1a, Il1b, Tnf) and chemokine (e.g.Ccl2, Ccl3, Ccl4, Ccl7) genes as well as IFN1-regulated genes (e.g. Irf7, Mx1, Oasl1, Ifit1), many of which were suppressed by DHA. Using single-cell regulatory network inference and clustering (SCENIC) to identify gene expression networks, we found DHA modestly downregulated LPS-induced expression of NF-κB-target genes. Importantly, LPS induced a subset of FLMs simultaneously expressing NF-κB- and IRF7/STAT1/STAT2-target genes that were conspicuously absent in DHA-pretreated FLMs. Thus, DHA potently targeted both the NF-κB and the IFN1 responses. Altogether, scRNAseq generated a valuable dataset that provides new insights into multiple overlapping mechanisms by which DHA may transcriptionally or post-transcriptionally regulate LPS-induced proinflammatory and IFN1-driven responses in macrophages.

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.

Mesenchymal stem cell transplantation alleviates Sjögren's syndrome symptoms by modulating Tim-3 expression

Mesenchymal stem cell (MSC) transplantation has been proven to be an effective treatment for Sjögren's syndrome (SS) to improve salivary gland pathology and exocrine function, but the mechanism remains unclear. A recently reported inhibitory receptor, Tim-3, also appears to be closely related to autoimmune diseases. Here, we aimed to explore the roles of Tim-3 in the pathogenesis of SS and MSC treatment. The results showed that Tim-3 was downregulated in T cells of SS patients and nonobese diabetic (NOD) mice, which is correlated with SS pathogenesis. MSC transplantation ameliorated SS-like symptoms and pathological changes in the submandibular glands with modulated Tim-3 expression, resulting in attenuation of localized inflammation, fibrosis, and epithelial-mesenchymal transition. Furthermore, Tim-3 is crucial for the inhibitory effect of MSCs on PBMC proliferation in vitro. Therefore, our work has demonstrated that MSC transplantation effectively mitigates the pathological changes of SS by regulating Tim-3 expression, which provides a novel mechanism of MSC treatment and indicates a brand-new perspective of the combination of inhibitory-receptor-targeted treatment and MSC therapy in SS.

The Type I Interferon Pathway Is Upregulated in the Cutaneous Lesions and Blood of Multibacillary Leprosy Patients With Erythema Nodosum Leprosum

In leprosy patients, acute inflammatory episodes, known as erythema nodosum leprosum (ENL), are responsible for high morbidity and tissue damage that occur during the course of Mycobacterium leprae infection. In a previous study, we showed evidence implicating DNA-sensing via TLR9 as an important inflammatory pathway in ENL. A likely important consequence of TLR9 pathway activation is the production of type I interferons (IFN-I) by plasmacytoid dendritic cells (pDCs), also implicated in the pathogenesis of several chronic inflammatory diseases. In this study, we investigated whether the IFN-I pathway is activated during ENL. Blood samples and skin lesions from multibacillary patients diagnosed with ENL were collected and the expression of genes of the IFN-I pathway and interferon-stimulated genes were compared with samples collected from non-reactional multibacillary (NR) patients. Whole blood RNAseq analysis suggested higher activation of the IFN-I pathway in ENL patients, confirmed by RT-qPCR. Likewise, significantly higher mRNA levels of IFN-I-related genes were detected in ENL skin biopsies when compared to NR patient lesions. During thalidomide administration, the drug of choice for ENL treatment, a decrease in the mRNA and protein levels of some of these genes both in the skin and blood was observed. Indeed, in vitro assays showed that thalidomide was able to block the secretion of IFN-I by peripheral blood mononuclear cells in response to M. leprae sonicate or CpG-A, a TLR9 ligand. Finally, the decreased frequencies of peripheral pDCs in ENL patients, along with the higher TLR9 expression in ENL pDCs and the enrichment of CD123⁺ cells in ENL skin lesions, suggest the involvement of these cells as IFN-I producers in this type of reaction. Taken together, our data point to the involvement of the pDC/type I IFN pathway in the pathogenesis of ENL, opening new avenues in identifying biomarkers for early diagnosis and new therapeutic targets for the better management of this reactional episode.