RNA sequencing of primary Sjögren’s syndrome neutrophils
Ontology highlight
ABSTRACT: Objective Neutrophils and aberrant NETosis have been implicated in the pathogenesis of diverse autoimmune diseases, however, their roles in primary Sjögren’s syndrome (pSS) remain unclear. We aimed to reveal the potential roles of neutrophils and neutrophil extracellular traps (NETs) in this study. Methods pSS patients were enrolled according to the corresponding diagnostic criteria. NETosis markers were measured in plasma and small salivary gland using ELISA and immunofluorescence. The gene signatures of neutrophils were assessed by RNA-Seq and RT-PCR. Reactive oxygen species (ROS), mitochondrial ROS (mitoROS) production and JC-1 was measured by flow cytometry. Results NETosis markers including cell free-DNA (cf-DNA), myeloperoxidase (MPO) in plasma and small salivary gland from pSS patients were significantly higher than healthy controls (HCs) and were associated with disease activity. RNA sequencing and RT-qPCR revealed activated Type I IFN signaling pathway and higher expression of type I interferon related genes in pSS neutrophils. Further stimulating with IFN-α 2a in vitro significantly induced ROS production and JC-1 monomer percentage in pSS neutrophils. Conclusions Our data suggest the involvement of neutrophils and enhanced NETosis in pSS patients. Further mechanism study in vitro revealed that type I IFN activation in pSS neutrophils led to mitochondrial damage and related ROS production which finally result in the generation of NETs.
Project description:Objective: Behçet's disease (BD) is a systemic vasculitis with inflammatory lesions mediated by cytotoxic T cells and neutrophils. Apremilast, an orally available small-molecule that selectively inhibits phosphodiesterase 4 (PDE4), has been recently approved for the treatment of BD. We aimed to investigate the effect of PDE4 inhibition on neutrophil activation in BD. Methods: We studied surface markers and reactive oxygen species (ROS) by flow cytometry, neutrophils extra cellular traps (NETs) and molecular signature of neutrophils by transcriptomic before and after PDE4 inhibition. Results: Activation surface markers (CD64, CD66b, CD11b and CD11c), ROS production and NETosis were up-regulated in BD as compared to Healthy Donors (HD) neutrophils. Transcriptome analysis showed 1021 significantly dysregulated neutrophils genes between BD and HD. Among dysregulated genes, we highlighted a great enrichment for pathways linked to innate immunity, intracellular signaling and chemotaxis in BD. Skin lesions of BD showed increased infiltration of neutrophils that co-localized with PDE4. Inhibition of PDE4 by apremilast strongly inhibited neutrophil surface activation markers as well as ROS production, NETosis, and genes and pathways related to innate immunity, intracellular signaling and chemotaxis. Conclusion: We pointed out key biological effects of apremilast on neutrophils in BD.
Project description:Our group has proposed that low-density granulocytes (LDGs) play an important role in lupus pathogenesis, as they can damage endothelial cells and synthesize increased levels of proinflammatory cytokines and type I interferons. LDGs have a heightened capacity to synthesize neutrophil extracellular traps (NETs). NETs from LDGs display increased levels of bactericidal and immunostimulatory proteins, such as the cathelicidin LL37 and externalize double-stranded DNA (dsDNA). Lupus netting LDGs have increased capacity to kill endothelial cells and expose IL-17. Through NETosis, lupus neutrophils stimulate plasmacytoid DCs to synthesize IFN-?. Our results further expand the potential pathogenic role of aberrant lupus neutrophils through a NET-mediated effect. We used microarrays to analyze the gene expression of neutrophils in healthy and lupus patients, and of low-density granulocytes in lupus patients. Human neutrophils and LDGs were isolated from PBMCs. RNA from healthy neutrophils, lupus neutrophils and lupus LDGs was extracted and processed for hybridization on Affymetrix microarrays.
Project description:Primary Sjögren’s syndrome (pSS) is a systemic autoimmune disease characterized by lymphocytic infiltration of the exocrine glands. Conventional dendritic cells (cDCs)-2 play a critical role in T and B cell activation, leading to germinal centre formation and autoantibody production. To understand the mechanisms underlying cDC2 dysregulation in pSS we performed RNA-sequencing analysis and functional validation on circulating cDC2s from pSS, non-Sjögren’s sicca (nSS) patients and healthy controls (HC). Two independent cohorts were established to identify reproducible dysregulated signatures, which included the interferon (IFN), toll-like receptors (TLR) signaling and antigen processing and presentation pathways. We confirm by flow cytometry that pSS-cDC2s were less efficient to degrade BSA but more efficient to uptake BSA both linked with the presence of anti-SSA antibodies. As the majority of the SSA+ pSS patients exhibit an IFN-signature, we tested whether IFNα priming would influence cDC2s antigen-uptake and processing. IFNα priming increased cDC2s uptake capacity, but not antigen processing. Additionally, pSS-cDC2s showed an increased uptake capacity of apoptotic salivary gland epithelial cells. Finally, pSS-cDC2s increased the proliferation of HC CD4+ T cells and the expression of CXCR3 and CXCR5 on the proliferating HC CD4+ T cells, contributing to T cell migration into the inflamed salivary glands. Here we provide the first in-depth molecular characterization of pSS-cDC2s and show that the transcriptomic and functional alterations observed in pSS-cDC2s are linked to IFN-signature. In view of its role in pSS immunopathology, delineating the molecular networks that drive cDC2s holds promise for targeting these cells in pSS.
Project description:Objective: The aim of this study was to characterize and compare the proteome in whole saliva, plasma, and salivary gland tissue in patients with primary Sjögren’s syndrome (pSS) and patients having symptoms of pSS, but not fulfilling the classification criteria, and to search for diagnostic biomarker candidates for pSS. Methods: Liquid chromatography tandem mass spectrometry was conducted on whole saliva, plasma, and labial salivary gland tissue samples from 24 patients with pSS and 16 non-Sjögren control subjects (non-pSS). Gene Ontology (GO)-terms and Kyoto Encyclopedia of Genes and Genomes (KEGG)-pathways were applied for functional annotation. Results: 1,013 proteins were identified in whole saliva, 219 in plasma, and 3,166 in salivary gland tissue. In saliva, 40 proteins differed significantly between the two groups. In pSS, proteins involved in immunoinflammatory processes were upregulated, whereas proteins related to salivary secretion were downregulated. The combination of neutrophil elastase, calreticulin, and tripartite motif-containing protein 29 yielded a receiver-operating characteristic (ROC) value of 0.97 (CI 0.93-1.00). Protein expression in plasma and salivary gland tissue did not differ between the patient groups. Conclusion: The salivary proteome of patients with pSS differed from that of non-pSS patients, indicating that saliva proteomics represents a promising non-invasive diagnostic tool for pSS.
Project description:Neutrophil Extracellular Traps (NETs) are structures consisting of chromatin and antimicrobial molecules that are released by neutrophils during a form of regulated cell death called NETosis. NETs trap invading pathogens, promote coagulation and activate myeloid cells to produce Type I interferons (type I IFN), proinflammatory cytokines that regulate the immune system. The mechanism of NET recognition by myeloid cells is not yet clearly identified. Here we show that macrophages and other myeloid cells phagocytose NETs. Once in phagosomes, NETs translocate to the cytosol, where they activate the DNA sensor cyclic GMP-AMP synthase (cGAS) and induce type I IFN expression. cGAS recognizes the DNA backbone of NETs. Interestingly, the NET associated serine protease Neutrophil Elastase (NE) mediates the activation of the pathway. We confirmed that NETs activate cGAS in vivo. Thus, our findings identify cGAS as a major sensor of NETs, mediating the immune activation during infection and in auto-immune diseases.
Project description:Neutrophils are short-lived innate immune cells. Upon encountering appropriate stimuli, neutrophils generate and release neutrophil extracellular traps (NETs), primarily via NADPH oxidase (Nox)-dependent (~2 hours) or Nox-independent NETosis (~15-60 minutes). Ironically, DNA transcription in dying neutrophils remains an enigma. We hypothesized that transcriptional activation, regulated by NETosis-specific kinases, is important to drive the chromatin decondensation necessary for NETosis. For the first time, we show here that (i) the degree of NETosis corresponds to the degree of genome-wide transcription; (ii) kinase-specific transcriptional activation reflects transcriptional firing during different types of NETosis; and (iii) Transcriptomics suggests that NETosis could differentially regulate inflammation. Therefore, we propose that the initial steps of transcriptional firing, but neither transcription per se help to drive NETosis.
Project description:Our group has proposed that low-density granulocytes (LDGs) play an important role in lupus pathogenesis, as they can damage endothelial cells and synthesize increased levels of proinflammatory cytokines and type I interferons. LDGs have a heightened capacity to synthesize neutrophil extracellular traps (NETs). NETs from LDGs display increased levels of bactericidal and immunostimulatory proteins, such as the cathelicidin LL37 and externalize double-stranded DNA (dsDNA). Lupus netting LDGs have increased capacity to kill endothelial cells and expose IL-17. Through NETosis, lupus neutrophils stimulate plasmacytoid DCs to synthesize IFN-α. Our results further expand the potential pathogenic role of aberrant lupus neutrophils through a NET-mediated effect. We used microarrays to analyze the gene expression of neutrophils in healthy and lupus patients, and of low-density granulocytes in lupus patients.
Project description:Primary Sjogren’s syndrome (pSS) is an autoimmune disease characterized by xerostomia (dry mouth), lymphocytic infiltration into salivary glands and the presence of SSA and SSB autoantibodies. Xerostomia is caused by hypofunction of the salivary glands and has been considered a driver in pSS development. Saliva production is regulated by sympathetic input into the gland initiating intracellular Ca2+ signals that activate the store operated Ca2+ entry (SOCE) pathway eliciting sustained Ca2+ influx. SOCE is mediated by the STIM1 and STIM2 proteins and the ORAI1 Ca2+ channel. However, there are no studies on the effects of lack of STIM1/2 function in salivary acini in animal models or its impact on pSS. Here we report that male and female mice lacking Stim1 and Stim2 (Stim1/2K14Cre) in salivary glands hyposalivate upon pilocarpine stimulation and showed reduced intracellular Ca2+ levels via SOCE in parotid acini. Bulk RNASeq of the parotid glands of Stim1/2K14Cre showed a decrease in Stim1/2 genes but not in other Ca2+ associated genes mediating saliva fluid secretion, yet SOCE was functionally required for the activation of the Ca2+ activated chloride channel ANO1. Ageing Stim1/2K14Cre mice showed no evidence of lymphocytic infiltration in the glands or elevated levels of SSA or SSB autoantibodies in the serum which may be linked to the downregulation of the toll-like receptor 8 (Tlr8) in Stim1/2K14Cre mice. This is supported by an increase in TLR8 gene expression in a salivary gland cell line following SOCE stimulation. Moreover, salivary gland biopsies of pSS patients showed increased STIM1 and TLR8 expression. These results implicate SOCE as an important activator of ANO1 and saliva fluid secretion in salivary glands but loss of SOCE does not result in pSS. Importantly, our data suggest a link between SOCE and TLR8 signaling which may have implications in inflammatory responses in salivary glands.
Project description:Panton-Valentine Leukocidin (PVL) is a Staphylococcus aureus toxin that binds to and kills human neutrophils resulting in the formation of neutrophil extracellular traps. A subset of individuals colonized with PVL expressing S. aureus suffer from recurring infections. We found that neutrophils from affected individuals display increased spontaneous NET formation after isolation, and increased sensitivity to killing by PVL. Compared to healthy controls, the expression of the target receptors for PVL, CD45 and C5L2, but not CD88, was increased in these patients, and the expression correlated to the amount of PVL-induced NETs produced. NADPH-oxidase activity was not important for PVL induced NETosis as neutrophils from CGD patients produced NETs in response to PVL. Through NET proteome analysis we identified that the protein content of PVL induced NETs is different from mitogen induced NETs. The abundance of the antimicrobial proteins LL37, myeloperoxidase, azurocidin, and proteinase 3 was lower on PVL NETs and PVL-induced NETs were deficient in killing Staphylococcus aureus. Neutrophils from patients that suffer from recurring PVL-positive infections may be more sensitive to PVL-induced NETosis, impairing their ability to combat the infection.
Project description:TcpC is a multifunctional virulence factor of uropathogenic E. coli (UPEC). Neutrophil extracellular trap formation (NETosis) is a crucial anti-infection mechanism of neutrophils. Here we show the influence of TcpC on NETosis and related mechanisms. In situ NETosis of kidneys from pyelonephritis mouse model induced by TcpC-secreting wild-type CFT073 (CFT073wt) and LPS-induced in vitro NETosis in CFT073wt- or recombinant TcpC (rTcpC)-treated neutrophils are inhibited. rTcpC enters neutrophils through caveolin-mediated endocytosis and inhibits LPS-induced production of ROS, proinflammatory cytokines and protein but not mRNA levels of peptidylarginine deiminase 4 (PAD4). rTcpC treatment enhances PAD4 ubiquitination and accumulation in proteasomes. Moreover, in vitro ubiquitination kit analyses suggest that TcpC is a PAD4-targetd E3 ubiquitin-ligase. These data suggest that TcpC inhibits NETosis primarily by serving as an E3 ligase that promotes degradation of PAD4. Our findings provide a novel mechanism underlying TcpC-mediated innate immune evasion.