Interferon Signature Research Articles

Non-Skewed X-inactivation Results in NF-κB Essential Modulator (NEMO) Δ-exon 5-autoinflammatory Syndrome (NEMO-NDAS) in a Female with Incontinentia Pigmenti

PurposeGenetic hypomorphic defects in X chromosomal IKBKG coding for the NF-κB essential modulator (NEMO) lead to ectodermal dysplasia and immunodeficiency in males and the skin disorder incontinentia pigmenti (IP) in females, respectively. NF-κB essential modulator (NEMO) Δ-exon 5-autoinflammatory syndrome (NEMO-NDAS) is a systemic autoinflammatory disease caused by alternative splicing and increased proportion of NEMO-Δex5. We investigated a female carrier presenting with IP and NEMO-NDAS due to non-skewed X-inactivation.MethodsIKBKG transcripts were quantified in peripheral blood mononuclear cells isolated from the patient, her mother, and healthy controls using RT-PCR and nanopore sequencing. Corresponding proteins were analyzed by western blotting and flow cytometry. Besides toll-like receptor (TLR) and tumor necrosis factor (TNF) signaling, the interferon signature, cytokine production and X-inactivation status were investigated.ResultsIP and autoinflammation with recurrent fever, oral ulcers, hepatitis, and neutropenia, but no immunodeficiency was observed in a female patient. Besides moderately reduced NEMO signaling function, type I interferonopathy, and elevated IL-18 and CXCL10 were found. She and her mother both carried the heterozygous variant c.613 C > T p.(Gln205*) in exon 5 of IKBKG previously reported in NEMO-deficient patients. However, X-inactivation was skewed in the mother, but not in the patient. Alternative splicing led to increased ratios of NEMO-Dex5 over full-length protein in peripheral blood cell subsets causing autoinflammation. Clinical symptoms partially resolved under treatment with TNF inhibitors.ConclusionNon-skewed X-inactivation can lead to NEMO-NDAS in females with IP carrying hypomorphic IKBKG variants due to alternative splicing and increased proportions of NEMO-∆ex5.

The Cardioprotective Role of Neutrophil-Specific STING in Myocardial Ischemia/Reperfusion Injury.

Neutrophils are the most rapid and abundant immune cells to infiltrate the myocardium following myocardial ischemia/reperfusion injury (MI/R). Neutrophil heterogeneity has not been well characterized in MI/R, and studies have shown conflicting results regarding the impact of neutrophil depletion on cardiac injury. We thus aim to study the impact of neutrophils with enriched type I interferon signature and the role of STING (stimulator of interferon genes) signaling in neutrophils on cardiac reperfusion injury. We utilized single-cell RNA sequencing to study neutrophil heterogeneity in response to MI/R. We generated a neutrophil-specific STING knockout mouse to assess the role of neutrophil STING in a model of MI/R. We examined cardiac function following injury via echocardiography and assessed the immune cell trajectory following injury utilizing flow cytometry. We identified a population of neutrophils with enriched type I interferon signaling and response to type I interferon following MI/R. We found that genetic deletion of neutrophil-specific STING led to worsened cardiac function following MI/R. Further investigation of the immune response by flow cytometry revealed decreased neutrophil infiltration into the myocardium and a shift in macrophage polarization. Our findings suggest that neutrophil-specific STING is cardioprotective in MI/R, partly due to its effects on downstream immune cells. These results demonstrate that early alterations or therapeutic interventions can influence key events in the resolution of inflammation following MI/R.

HDAC6 Deletion Decreases Pristane-induced Inflammation.

Systemic lupus erythematosus is an autoimmune disease characterized by excessive inflammation and production of pathogenic Abs. Histone deacetylase 6 (HDAC6) is a class IIb histone deacetylase. It has been reported that selective HDAC6 inhibition decreases inflammation in lupus mouse models. In this study, sex- and age-matched wild-type (WT) and HDAC6-/- mice on the C57BL/6 background were administered 0.5 ml of pristane or PBS i.p. at 8-12 wk of age and were euthanized 10 d later. At sacrifice, body weight and spleen weight were measured, sera were collected, and splenocytes and peritoneal cells were harvested for flow cytometry. We found pristane administration increased the spleen weight with no difference between WT and HDAC6-/- mice. Pristane administration promoted the population of CD11b+Ly6C++ inflammatory monocytes and CD11b+Ly6G+ neutrophils. Peritoneal recruitment of these inflammatory monocytes and neutrophils was significantly decreased in HDAC6-/- mice compared with the WT mice. Flow cytometry results showed that the number of CD69+ T and B cells was increased in HDAC6-/- mice. Pristane administration also induced the IFN signature genes as determined by RT-qPCR. Furthermore, IFN signature genes were not affected in HDAC6-/- mice compared with the WT mice. In vitro studies in J774A.1 cells revealed that the selective HDAC6 inhibitor (ACY-738) increased acetylation of NF-κB while increasing Stat1 phosphorylation, which resulted in inducible NO synthase production in LPS/IFN-γ-stimulated cells. Taken together, these results demonstrate that although HDAC6 inhibition may inhibit some inflammatory pathways, others remain unaffected.

New and future perspectives in familial Mediterranean fever and other autoinflammatory diseases.

Systemic autoinflammatory diseases are a group of disorders characterized by sterile episodes of inflammation resulting from defects in the innate immune system. In contrast to classical autoimmune diseases, where circulating autoantibodies and the adaptive immune system are involved, these conditions involve excessive presence of proinflammatory cytokines leading to inflammatory attacks. Excessive cytokine production, functional mutations in regulatory pathways, excessive interferon production, defects in the nuclear factor-kappa B signaling pathway, abnorARCHmal protein folding, and complement activation are the mechanisms leading to autoinflammatory diseases. A defect in the mTOR pathway and trained immunity are newly discovered possible causes in pathogenesis. Early onset and severe forms of classical rheumatological diseases have been more frequently associated with autoinflammatory diseases in the last decade. Therefore, monogenic autoinflammatory diseases should be considered in rheumatic diseases with family history, consanguinity, early onset, and severe disease. The combination of functional and genotyping research will help to identify unclassified patients. The optimal treatment strategy remains uncertain, functional studies such as interferon signature and cytokine profiling, may prove valuable in guiding the treatment process. Stem cell transplantation strategies in autoinflammatory diseases with partial response to biological therapies can be considered. Autoinflammatory diseases are becoming increasingly complex and are bringing new perspectives to already known rheumatic diseases. Although we have effective treatments, we are still far from personalized recommendations.

The assembly of neutrophil inflammasomes during COVID-19 is mediated by type I interferons.

The severity of COVID-19 is linked to excessive inflammation. Neutrophils represent a critical arm of the innate immune response and are major mediators of inflammation, but their role in COVID-19 pathophysiology remains poorly understood. We conducted transcriptomic profiling of neutrophils obtained from patients with mild and severe COVID-19, as well as from SARS-CoV-2 infected mice, in comparison to non-infected healthy controls. In addition, we investigated the inflammasome formation potential in neutrophils from patients and mice upon SARS-CoV-2 infection. Transcriptomic analysis of polymorphonuclear cells (PMNs), consisting mainly of mature neutrophils, revealed a striking type I interferon (IFN-I) gene signature in severe COVID-19 patients, contrasting with mild COVID-19 and healthy controls. Notably, low-density granulocytes (LDGs) from severe COVID-19 patients exhibited an immature neutrophil phenotype and lacked this IFN-I signature. Moreover, PMNs from severe COVID-19 patients showed heightened nigericin-induced caspase1 activation, but reduced responsiveness to exogenous inflammasome priming. Furthermore, IFN-I emerged as a priming stimulus for neutrophil inflammasomes. These findings suggest a potential role for neutrophil inflammasomes in driving inflammation during severe COVID-19. Altogether, these findings open promising avenues for targeted therapeutic interventions to mitigate the pathological processes associated with the disease.

Interferon gene expression declines over time post-COVID infection and in long COVID patients

Background Interferons (IFNs) represent a first-line defense against viruses and other pathogens. It has been shown that an impaired and uncontrolled release of these glycoproteins can result in tissue damage and explain severe progression of coronavirus disease 2019 (COVID-19). However, their potential role in Long-COVID syndrome (LC) remains debateable. Objectives The objective of the present study is to shed further light on the possible role of IFNs (and related genes) gene expression patterns in the progression of COVID-19 and LC patients. Methods We carried out a multi-cohort study by analyzing the IFN gene expression patterns (using different IFN gene signatures) in five cohorts of acute COVID-19 (n = 541 samples) and LC patients (n = 188), and compared them to patterns observed in three autoimmune diseases (systemic lupus erythematous [n = 242], systemic sclerosis [n = 91], and Sjögren’s syndrome [n = 282]). Results The data show that, while the interferon signatures are strongly upregulated in severe COVID-19 patients and autoimmune diseases, it decays with the time from symptoms onset and in LC patients. Differential pathway analysis of IFN-related terms indicates an over activation in autoimmune diseases (IFN-I/II) and severe COVID-19 (IFN-I/II/III), while these pathways are mostly inactivated or downregulated in LC (IFN-I/III). By analyzing six proteomic LC datasets, we did not find evidence of a role of IFNs in this condition. Conclusion Our findings suggest a potential role of cytokine exhaustion mediated by IFN gene expression inactivation as a possible driver of LC.

Transcriptomic observations of intra and extracellular immunotherapy targets for pediatric brain tumors

ABSTRACT Objectives Despite surgical resection, chemoradiation, and targeted therapy, brain tumors remain a leading cause of cancer-related death in children. Immunotherapy has shown some promise and is actively being investigated for treating childhood brain tumors. However, a critical step in advancing immunotherapy for these patients is to uncover targets that can be effectively translated into therapeutic interventions. Methods In this study, our team performed a transcriptomic analysis across pediatric brain tumor types to identify potential targets for immunotherapy. Additionally, we assessed components that may impact patient response to immunotherapy, including the expression of genes essential for antigen processing and presentation, inhibitory ligands and receptors, interferon signature, and overall predicted T cell infiltration. Results We observed distinct expression patterns across tumor types. These included elevated expression of antigen genes and antigen processing machinery in some tumor types while other tumors had elevated inhibitory checkpoint receptors, known to be associated with response to checkpoint inhibitor immunotherapy. Conclusion These findings suggest that pediatric brain tumors exhibit distinct potential for specific immunotherapies. We believe our findings can guide investigators in their assessment of appropriate immunotherapy classes and targets in pediatric brain tumors.

Pediatric glioma immune profiling identifies TIM3 as a therapeutic target in BRAF fusion pilocytic astrocytoma.

Despite being the leading cause of cancer-related childhood mortality, pediatric gliomas have been relatively understudied, and the repurposing of immunotherapies has not been successful. Whole-transcriptome sequencing, single-cell sequencing, and sequential multiplex immunofluorescence were used to identify an immunotherapeutic strategy that could be applied to multiple preclinical glioma models. MAPK-driven pediatric gliomas have a higher IFN signature relative to other molecular subgroups. Single-cell sequencing identified an activated and cytotoxic microglia (MG) population designated MG-Act in BRAF-fused, MAPK-activated pilocytic astrocytoma (PA), but not in high-grade gliomas or normal brain. T cell immunoglobulin and mucin domain 3 (TIM3) was expressed on MG-Act and on the myeloid cells lining the tumor vasculature but not normal brain vasculature. TIM3 expression became upregulated on immune cells in the PA microenvironment, and anti-TIM3 reprogrammed ex vivo immune cells from human PAs to a proinflammatory cytotoxic phenotype. In a genetically engineered murine model of MAPK-driven, low-grade gliomas, anti-TIM3 treatment increased median survival over IgG- and anti-PD-1-treated mice. Single-cell RNA-Seq data during the therapeutic window of anti-TIM3 revealed enrichment of the MG-Act population. The therapeutic activity of anti-TIM3 was abrogated in mice on the CX3CR1 MG-KO background. These data support the use of anti-TIM3 in clinical trials of pediatric low-grade, MAPK-driven gliomas.

Interferon-induced protein 44 (IFI44) and interferon regulatory factor 4 (IRF4) gene expression in rheumatoid arthritis

ABSTRACT Background and objectives The type I interferon (IFN) signature has been found to be overactivated in many systemic autoimmune diseases. This may be explained by impaired regulation of interferon-stimulated genes (ISGs) as well as interferon-induced protein 44 (IFI44) expression via their regulatory mechanisms via interferon regulatory factors (IRFs). Patients and methods This case-control study includes two groups: 50 RA patients and 50 healthy controls. The quantification of IFI44 and IRF4 expression levels by the real-time PCR technique was estimated. Disease Activity Score-28 (DAS-28) was estimated for RA patients only. Results Among the RA patients, there were statistically significant increased ESR, CRP, TLC, RF, and anti-CCP levels (p value < 0.001) and significant increased expression of the IFI44 and IRF4 genes (p value < 0.001). There was a significant positive correlation between the IFI44 and IRF4, and there was a significant correlation between both and ESR and anti-CCP among RA patients. At a cutoff point of 1.95, IFI44 shows higher sensitivity and specificity values than IRF4 for the diagnosis of RA. Conclusion IFI44 was more sensitive for RA diagnosis than IRF4. IFI44 and IRF4 overexpression could be promising predictors of RA diagnosis and might become useful clinical tools to guide therapeutic strategies.

Toll-like Receptor Homologue CD180 Ligation of B Cells Upregulates Type I IFN Signature in Diffuse Cutaneous Systemic Sclerosis.

Type I interferon (IFN-I) signaling has been shown to be upregulated in systemic sclerosis (SSc). Dysregulated B-cell functions, including antigen presentation, as well as antibody and cytokine production, all of which may be affected by IFN-I signaling, play an important role in the pathogenesis of the disease. We investigated the IFN-I signature in 71 patients with the more severe form of the disease, diffuse cutaneous SSc (dcSSc), and 33 healthy controls (HCs). Activation via Toll-like receptors (TLRs) can influence the IFN-I signaling cascade; thus, we analyzed the effects of the TLR homologue CD180 ligation on the IFN-I signature in B cells. CD180 stimulation augmented the phosphorylation of signal transducer and activator of transcription 1 (STAT1) in dcSSc B cells (p = 0.0123). The expression of IFN-I receptor (IFNAR1) in non-switched memory B cells producing natural autoantibodies was elevated in dcSSc (p = 0.0109), which was enhanced following anti-CD180 antibody treatment (p = 0.0125). Autoantibodies to IFN-Is (IFN-alpha and omega) correlated (dcSSc p = 0.0003, HC p = 0.0192) and were present at similar levels in B cells from dcSSc and HC, suggesting their regulatory role as natural autoantibodies. It can be concluded that factors other than IFN-alpha may contribute to the elevated IFN-I signature of dcSSc B cells, and one possible candidate is B-cell activation via CD180.

Type I interferon gene expression signature as a marker to predict response to cyclophosphamide based treatment in proliferative lupus nephritis.

To assess the longitudinal effect of cyclophosphamide (CYC) treatment on type-I interferon (IFN) signature in proliferative lupus nephritis (LN) and its role in predicting treatment response. Fifty-four biopsy proven proliferative LN patients scheduled to receive high-dose (HD) or low-dose (LD) CYC were recruited and followed up for six months. At six months, patients were classified as clinical responders (CR) or non-responders (NR) to treatment, using the EULAR/EDTA criteria. An IFN-gene based score (IGS) was developed from the mean log-transformed gene expression of MX1, OAS1, IFIT1, OASL, IFIT4, LY6E, IRF7 at baseline, three and six months. Longitudinal changes of IGS within and between groups were assessed and ΔIGS, which is the difference in IGS between baseline and three months was calculated. Independent predictors of non-response were identified and an ROC analysis was performed to evaluate their utility to predict NR. There was a dynamic change in IGS within the HD, LD, CR, and NR groups. Compared to baseline, there was a significant decrease in IGS at three months in HD and LD groups (HD group: 2.01 to 1.14, p = .001; LD group = 2.01 to 0.81, p < .001), followed by a significant increase from three to six months in LD group (LD: 0.81 to 1.51, p = .03; HD: 1.14 to 1.54, p = .300). A decrease in IGS from baseline to three months was seen in both CR (2.13 to 0.79, p < .001) and NR groups (1.83 to 1.27, p = .046), and a significant increase from three to six months was observed only in the CR group (CR: 0.79 to 1.57, p = .006; NR: 1.27 to 1.46, p = 1). ΔIGS (baseline to three months) was higher in CR compared to NR group (-1.339 vs -0.563, p = .017). ROC analysis showed that the model comprising of 0.81 fold decrease in IGS from baseline to three months, endocapillary hypercellularity and interstitial inflammation on renal histopathology predicted non-response with a sensitivity of 83.3% and specificity of 71.4%. In proliferative LN, treated with HD or LD-CYC, combined model comprising of decrease in IGS score by 0.81 fold from baseline to three months, along with important histopathological features such as endocapillary hypercellularity and interstitial inflammation had better predictive capability for non-response.

Positionally distinct interferon stimulated dermal immune acting fibroblasts promote neutrophil recruitment in Sweet's syndrome.

Sweet's syndrome is a poorly understood inflammatory skin disease characterized by neutrophil infiltration to the dermis. Single-nucleus and bulk transcriptomics of archival clinical samples of Sweet's syndrome revealed a prominent interferon signature in Sweet's syndrome skin that was reduced in tissue from other neutrophilic dermatoses. This signature was observed in different subsets of cells, including fibroblasts that expressed interferon-induced genes. Functionally, this response was supported by analysis of cultured primary human dermal fibroblasts that were observed to highly express neutrophil chemokines in response to activation by type I interferon. Furthermore, single-molecule resolution spatial transcriptomics of skin in Sweet's syndrome identified positionally distinct immune acting fibroblasts that included a CXCL1+ subset proximal to neutrophils and a CXCL12+ subset distal to the neutrophilic infiltrate. This study defines the cellular landscape of neutrophilic dermatoses and suggests dermal immune acting fibroblasts play a role in the pathogenesis of Sweet's syndrome through recognition of type I interferons.

Cellular spermine targets JAK signaling to restrain cytokine-mediated autoimmunity

Prolonged activation of the type I interferon (IFN-I) pathway leads to autoimmune diseases such as systemic lupus erythematosus (SLE). Metabolic regulation of cytokine signaling is critical for cellular homeostasis. Through metabolomics analyses of IFN-β-activated macrophages and an IFN-stimulated-response-element reporter screening, we identified spermine as a metabolite brake for Janus kinase (JAK) signaling. Spermine directly bound to the FERM and SH2 domains of JAK1 to impair JAK1-cytokine receptor interaction, thus broadly suppressing JAK1 phosphorylation triggered by cytokines IFN-I, IFN-II, interleukin (IL)-2, and IL-6. Peripheral blood mononuclear cells (PBMCs) from individuals with SLE showing decreased spermine concentrations exhibited enhanced IFN-I and lupus gene signatures. Spermine treatment attenuated autoimmune pathogenesis in SLE and psoriasis mice and reduced IFN-I signaling in monocytes from individuals with SLE. We synthesized a spermine derivative (spermine derivative 1 [SD1]) and showed that it had a potent immunosuppressive function. Our findings reveal spermine as a metabolic checkpoint for cellular homeostasis and a potential immunosuppressive molecule for controlling autoimmune disease.

Association of autoantibodies with the IFN signature and NETosis in patients with systemic lupus erythematosus

ObjectiveSystemic lupus erythematosus (SLE) is an autoimmune disease characterized by a variety of disease symptoms and an unpredictable clinical course. To improve treatment outcome, stratification based on immunological manifestations commonly seen in patients with SLE such as autoantibodies, type I interferon (IFN) signature and neutrophil extracellular trap (NET) release may help. It is assumed that there is an association between these immunological phenomena, since NET release induces IFN production and IFN induces autoantibody formation via B-cell activation. Here we studied the association between autoantibodies, the IFN signature, NET release, and clinical manifestations in patients with SLE. MethodsWe performed principal component analysis (PCA) and hierarchical clustering of 57 SLE-related autoantibodies in 25 patients with SLE. We correlated each autoantibody to the IFN signature and NET inducing capacity. ResultsWe observed two distinct clusters: one cluster contained mostly patients with a high IFN signature. Patients in this cluster often present with cutaneous lupus, and have higher anti-dsDNA concentrations. Another cluster contained a mix of patients with a high and low IFN signature. Patients with high and low NET inducing capacity were equally distributed between the clusters. Variance between the clusters is mainly driven by antibodies against histones, RibP2, RibP0, EphB2, RibP1, PCNA, dsDNA, and nucleosome. In addition, we found a trend towards increased concentrations of autoantibodies against EphB2, RibP1, and RNP70 in patients with an IFN signature. We found a negative correlation of NET inducing capacity with anti-FcER (r = −0.530; p = 0.007) and anti-PmScl100 (r = −0.445; p = 0.03). ConclusionWe identified a subgroup of patients with an IFN signature that express increased concentrations of antibodies against DNA and RNA-binding proteins, which can be useful for further patient stratification and a more targeted therapy. We did not find positive associations between autoantibodies and NET inducing capacity. Our study further strengthens the evidence of a correlation between RNA-binding autoantibodies and the IFN signature.

Fate-mapping and functional dissection reveal perilous influence of type I interferon signaling in mouse brain aging

BackgroundAging significantly elevates the risk of developing neurodegenerative diseases. Neuroinflammation is a universal hallmark of neurodegeneration as well as normal brain aging. Which branches of age-related neuroinflammation, and how they precondition the brain toward pathological progression, remain ill-understood. The presence of elevated type I interferon (IFN-I) has been documented in the aged brain, but its role in promoting degenerative processes, such as the loss of neurons in vulnerable regions, has not been studied in depth.MethodsTo comprehend the scope of IFN-I activity in the aging brain, we surveyed IFN-I-responsive reporter mice at multiple ages. We also examined 5- and 24-month-old mice harboring selective ablation of Ifnar1 in microglia to observe the effects of manipulating this pathway during the aging process using bulk RNA sequencing and histological parameters.ResultsWe detected age-dependent IFN-I signal escalation in multiple brain cell types from various regions, especially in microglia. Selective ablation of Ifnar1 from microglia in aged mice significantly reduced overall brain IFN-I signature, dampened microglial reactivity, lessened neuronal loss, restored expression of key neuronal genes and pathways, and diminished the accumulation of lipofuscin, a core hallmark of cellular aging in the brain.ConclusionsOverall, our study demonstrates pervasive IFN-I activity during normal mouse brain aging and reveals a pathogenic, pro-degenerative role played by microglial IFN-I signaling in perpetuating neuroinflammation, neuronal dysfunction, and molecular aggregation. These findings extend the understanding of a principal axis of age-related inflammation in the brain, one likely shared with multiple neurological disorders, and provide a rationale to modulate aberrant immune activation to mitigate neurodegenerative process at all stages.

Disease activity drives divergent epigenetic and transcriptomic reprogramming of monocyte subpopulations in systemic lupus erythematosus

ObjectivesSystemic lupus erythematosus (SLE) is characterised by systemic inflammation involving various immune cell types. Monocytes, pivotal in promoting and regulating inflammation in SLE, differentiate from classic monocytes into intermediate and...

Interferon signature in the development of SLE: molecular mechanisms, approaches to diagnosis and treatment

Interferon signature in the development of SLE: molecular mechanisms, approaches to diagnosis and treatment

An interactive web application for exploring systemic lupus erythematosus blood transcriptomic diversity.

In the field of complex autoimmune diseases such as systemic lupus erythematosus (SLE), systems immunology approaches have proven invaluable in translational research settings. Large-scale datasets of transcriptome profiling have been collected and made available to the research community in public repositories, but remain poorly accessible and usable by mainstream researchers. Enabling tools and technologies facilitating investigators' interaction with large-scale datasets such as user-friendly web applications could promote data reuse and foster knowledge discovery. Microarray blood transcriptomic data from the LUPUCE cohort (publicly available on Gene Expression Omnibus, GSE49454), which comprised 157 samples from 62 adult SLE patients, were analyzed with the third-generation (BloodGen3) module repertoire framework, which comprises modules and module aggregates. These well-characterized samples corresponded to different levels of disease activity, different types of flares (including biopsy-proven lupus nephritis), different auto-antibody profiles and different levels of interferon signatures. A web application was deployed to present the aggregate-level, module-level and gene-level analysis results from LUPUCE dataset. Users can explore the similarities and heterogeneity of SLE samples, navigate through different levels of analysis, test hypotheses and generate custom fingerprint grids and heatmaps, which may be used in reports or manuscripts. This resource is available via this link: https://immunology-research.shinyapps.io/LUPUCE/. This web application can be employed as a stand-alone resource to explore changes in blood transcript profiles in SLE, and their relation to clinical and immunological parameters, to generate new research hypotheses.

Elevated unphosphorylated STAT1 and IRF9 in T and B cells of primary sjögren's syndrome: Novel biomarkers for disease activity and subsets

ObjectivesAutoreactive B cells and interferon (IFN) signature are hallmarks of primary sjögren's syndrome (pSS), but how IFN signaling pathways influence autoantibody production and clinical manifestations remain unclear. More detailed studies hold promise for improved diagnostic methodologies and personalized treatment. MethodsWe analyzed peripheral blood T and B cell subsets from 34 pSS patients and 38 healthy donors (HDs) at baseline and upon stimulation regarding their expression levels of type I and II IFN signaling molecules (STAT1/2, IRF1, IRF9). Additionally, we investigated how the levels of these molecules correlated with serological and clinical characteristics and performed ROC analysis. ResultsPatients showed elevated IFN pathway molecules, including STAT1, STAT2 and IRF9 among most T and B cell subsets. We found a reduced ratio of phosphorylated STAT1 and STAT2 in patients in comparison to HDs, although B cells from patients were highly responsive by increased phosphorylation upon IFN stimulation. Correlation matrices showed further interrelations between STAT1, IRF1 and IRF9 in pSS. Levels of STAT1 and IRF9 in T and B cells correlated with the IFN type I marker Siglec-1 (CD169) on monocytes.High levels of STAT1 and IRF9 within pSS B cells were significantly associated with hypergammaglobulinemia as well as anti-SSA/anti-SSB autoantibodies. Elevated STAT1 levels were found in patients with extraglandular disease and could serve as a biomarker for this subgroup (p < 0.01). Notably, IRF9 levels in T and B cells correlated with EULAR Sjögren's syndrome disease activity index (ESSDAI). ConclusionHere, we provide evidence that in active pSS patients, enhanced IFN signaling incl. unphosphorylated STAT1 and STAT2 with IRFs entertain chronic T and B cell activation. Furthermore, increased STAT1 levels candidate as biomarker of extraglandular disease, while IRF9 levels can serve as biomarker for disease activity.

#1154 Type I interferon pathway is upregulated in microscopic polyangiitis (vs granulomatosis with polyangiitis)

Abstract Background and Aims The two main types of ANCA-associated vasculitis (AAV), microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA), share common characteristics but also differ on many aspects (epidemiological, genetic, clinical, outcomes). These differences did not justify, to date, different patient management. To identify more specific targetable pathways, we characterized the kidney transcriptome of MPA vs. GPA patients with AAV-glomerulonephritis (AAV-GN). Method This retrospective study included adult patients with AAV-GN from the French Maine-Anjou Registry. Immune gene transcript analysis was performed on RNA extracted from 97 kidney biopsies using NanoString technology. Significant transcripts were examined to identify immune pathways of interest. We then used a publicly available dataset to explore these identified pathways (qPCR / ELISA). Results We compared kidney biopsies from GPA (n = 33) and MPA (n = 64) patients. There was no difference in eGFR between both groups at diagnosis. Of the 750 evaluated immune transcripts, 8 genes were found differentially expressed between MPA and GPA patients, all being upregulated in MPA (log2FC &amp;gt; 1, q-value &amp;lt; 0.05) (Fig. 1A). Seven (out of 8) genes belonged to the type I interferon (IFN-I) signaling pathway. A personal analysis of unpublished, publicly available, data1 identified a significantly more pronounced IFN-I signature in the peripheral blood mononuclear cells of patients with MPO-AAV when compared to those with PR3-AAV (Fig. 1B). Serum levels or CXCL10, a cytokine that mediates immune responses through the recruitment and activation of numerous immune cells under the regulation of IFN-I, were found higher in MPO-AAV patients (Fig. 1C). Conclusion We identified a type I interferon signature, both in kidneys and in blood, in patients with MPA (or MPO-AAV) in comparison to GPA (or PR3-AAV). This is in line with previous lines of evidence brough by Kessenbrock et al. and Kessler et al. suggesting a role for IFN-I in AAV and especially in MPO-AAV. This signature may help gain a deeper understanding of the AAV-GN pathogenesis and provide insights for developing new therapeutic options.