{"title":"IRF5 Controls Plasma Cell Generation and Antibody Production via Distinct Mechanisms Depending on the Antigenic Trigger.","authors":"Bharati Matta, Jenna Battaglia, Margaret Lapan, Vinay Sharma, Betsy J Barnes","doi":"10.1111/imm.13879","DOIUrl":null,"url":null,"abstract":"<p><p>Elevated levels of serum autoantibodies are a hallmark of systemic lupus erythematosus (SLE) and are produced by plasma cells in response to a variety of antigenic triggers. In SLE, the triggers are complex and may include both T cell-dependent/-independent and TLR-dependent/-independent mechanisms of immune activation, which ultimately contributes to the significant immune dysregulation seen in patients at the level of cytokine production and cellular activation (B cells, T cells, dendritic cells, neutrophils and macrophages). Interferon regulatory factor 5 (IRF5) has been identified as an autoimmune susceptibility gene and polymorphisms in IRF5 associate with altered expression and hyper-activation in distinct SLE immune cell subsets. To gain further insight into the mechanisms that drive IRF5-mediated SLE immune activation, we characterised wild-type (WT) and Irf5<sup>-/-</sup> Balb/c mice in response to immunisation. WT and Irf5<sup>-/-</sup> Balb/c mice were immunised to activate various signalling pathways in vivo followed by systemic immunophenotyping and detection of antibody production by multi-colour flow cytometry and ELISPOT. We identified two pathways, TLR9-dependent and T cell-dependent that resulted in IRF5 cell type-specific function. Immunisation with either CpG-B + Alum or NP-KLH + Alum but not with R848 + Alum, NP-LPS + Alum or NP-Ficoll+Alum resulted in decreased plasma cell generation and reduced antibody production in Irf5<sup>-/-</sup> mice. Notably, the mechanism(s) leading to this downstream phenotype was distinct. In CpG-B + Alum immunised mice, we found reduced activation of plasmacytoid dendritic cells, resulting in reduced IFNα and IL6 production in Irf5<sup>-/-</sup> mice. Conversely, mice immunised with NP-KLH + Alum had reduced numbers of T follicular helper cells and germinal centre B cells with reduced expression of Bcl6 in Irf5<sup>-/-</sup> mice. Moreover, T follicular helper cells from Irf5<sup>-/-</sup> mice were functionally defective. Even though the downstream phenotype of reduced antibody production in Irf5<sup>-/-</sup> mice was conserved between T cell-dependent and TLR9-dependent immunisation, the mechanisms leading to this phenotype were antigen- and cell type-specific.</p>","PeriodicalId":13508,"journal":{"name":"Immunology","volume":" ","pages":""},"PeriodicalIF":4.9000,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Immunology","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1111/imm.13879","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"IMMUNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Elevated levels of serum autoantibodies are a hallmark of systemic lupus erythematosus (SLE) and are produced by plasma cells in response to a variety of antigenic triggers. In SLE, the triggers are complex and may include both T cell-dependent/-independent and TLR-dependent/-independent mechanisms of immune activation, which ultimately contributes to the significant immune dysregulation seen in patients at the level of cytokine production and cellular activation (B cells, T cells, dendritic cells, neutrophils and macrophages). Interferon regulatory factor 5 (IRF5) has been identified as an autoimmune susceptibility gene and polymorphisms in IRF5 associate with altered expression and hyper-activation in distinct SLE immune cell subsets. To gain further insight into the mechanisms that drive IRF5-mediated SLE immune activation, we characterised wild-type (WT) and Irf5-/- Balb/c mice in response to immunisation. WT and Irf5-/- Balb/c mice were immunised to activate various signalling pathways in vivo followed by systemic immunophenotyping and detection of antibody production by multi-colour flow cytometry and ELISPOT. We identified two pathways, TLR9-dependent and T cell-dependent that resulted in IRF5 cell type-specific function. Immunisation with either CpG-B + Alum or NP-KLH + Alum but not with R848 + Alum, NP-LPS + Alum or NP-Ficoll+Alum resulted in decreased plasma cell generation and reduced antibody production in Irf5-/- mice. Notably, the mechanism(s) leading to this downstream phenotype was distinct. In CpG-B + Alum immunised mice, we found reduced activation of plasmacytoid dendritic cells, resulting in reduced IFNα and IL6 production in Irf5-/- mice. Conversely, mice immunised with NP-KLH + Alum had reduced numbers of T follicular helper cells and germinal centre B cells with reduced expression of Bcl6 in Irf5-/- mice. Moreover, T follicular helper cells from Irf5-/- mice were functionally defective. Even though the downstream phenotype of reduced antibody production in Irf5-/- mice was conserved between T cell-dependent and TLR9-dependent immunisation, the mechanisms leading to this phenotype were antigen- and cell type-specific.
期刊介绍:
Immunology is one of the longest-established immunology journals and is recognised as one of the leading journals in its field. We have global representation in authors, editors and reviewers.
Immunology publishes papers describing original findings in all areas of cellular and molecular immunology. High-quality original articles describing mechanistic insights into fundamental aspects of the immune system are welcome. Topics of interest to the journal include: immune cell development, cancer immunology, systems immunology/omics and informatics, inflammation, immunometabolism, immunology of infection, microbiota and immunity, mucosal immunology, and neuroimmunology.
The journal also publishes commissioned review articles on subjects of topical interest to immunologists, and commissions in-depth review series: themed sets of review articles which take a 360° view of select topics at the heart of immunological research.