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Ordóñez NG. Value of melanocytic-associated immunohistochemical markers in the diagnosis of malignant melanoma: a review and update. Hum Pathol 2014; 45:191-205. [PMID: 23648379 DOI: 10.1016/j.humpath.2013.02.007] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Revised: 02/12/2013] [Accepted: 02/15/2013] [Indexed: 11/21/2022]
Abstract
Since the identification of S100 protein as an immunohistochemical marker that could be useful in the diagnosis of melanoma in the early 1980s, a large number of other melanocytic-associated markers that could potentially be used to assist in the differential diagnosis of these tumors have also been investigated. A great variation exists, however, among these markers, not only in their expression in some subtypes of melanoma, particularly desmoplastic melanoma, but also in their specificity because some of them can also be expressed in nonmelanocytic neoplasms, including various types of soft tissue tumors and carcinomas. This article reviews the information that is currently available on the practical value of some of the markers that have more often been recommended for assisting in the diagnosis of melanomas, including those that have only recently become available.
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Rangaswamy US, Speck SH. Murine gammaherpesvirus M2 protein induction of IRF4 via the NFAT pathway leads to IL-10 expression in B cells. PLoS Pathog 2014; 10:e1003858. [PMID: 24391506 PMCID: PMC3879372 DOI: 10.1371/journal.ppat.1003858] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 11/13/2013] [Indexed: 12/04/2022] Open
Abstract
Reactivation of the gammaherpesviruses Epstein-Barr virus (EBV), Kaposi's sarcoma-associated herpesvirus (KSHV) and murine gammaherpesvirus 68 (MHV68) from latently infected B cells has been linked to plasma cell differentiation. We have previously shown that the MHV68 M2 protein is important for virus reactivation from B cells and, when expressed alone in primary murine B cells, can drive B cell differentiation towards a pre-plasma cell phenotype. In addition, expression of M2 in primary murine B cells leads to secretion of high levels of IL-10 along with enhanced proliferation and survival. Furthermore, the absence of M2 in vivo leads to a defect in the appearance of MHV68 infected plasma cells in the spleen at the peak of MHV68 latency. Here, employing an inducible B cell expression system, we have determined that M2 activates the NFAT pathway in a Src kinase-dependent manner – leading to induction of the plasma cell-associated transcription factor, Interferon Regulatory Factor-4 (IRF4). Furthermore, we show that expression of IRF4 alone in a B cell line up-regulates IL-10 expression in culture supernatants, revealing a novel role for IRF4 in B cell induced IL-10. Consistent with the latter observation, we show that IRF4 can regulate the IL-10 promoter in B cells. In primary murine B cells, addition of cyclosporine (CsA) resulted in a significant decrease in M2-induced IL-10 levels as well as IRF4 expression, emphasizing the importance of the NFAT pathway in M2- mediated induction of IL-10. Together, these studies argue in favor of a model wherein M2 activation of the NFAT pathway initiates events leading to increased levels of IRF4 – a key player in plasma cell differentiation – which in turn triggers IL-10 expression. In the context of previous findings, the data presented here provides insights into how M2 facilitates plasma cell differentiation and subsequent virus reactivation. The human viruses Epstein-Barr Virus (EBV) and Kaposi's Sarcoma-associated herpesvirus (KSHV) are members of the gammaherpesvirus family – pathogens that are associated with cancers of lymphoid tissues. Murine gammaherpesvirus 68 (MHV68) infection of laboratory mice provides a small animal model to study how this family of viruses chronically infects their host. The gammaherpesvirus establish a quiescent infection (termed latency) for the lifetime of the individual. However, they are capable of producing progeny virus (termed reactivation) in response to a variety of immune or environmental stimuli. Differentiation of latently infected B cells into plasma cells (the cells producing antibodies) has been associated with reactivation from latency. Notably, the MHV68 M2 protein plays a role in driving differentiation of MHV68 infected B cells to plasma cells. Furthermore, M2 expression results in increased levels of IL-10 (an immune-regulatory cytokine). Here we show that M2 mediated IL-10 production occurs through induction of IRF4 expression, a key player in plasma cell differentiation. This process involves Src kinases and NFAT – both components of B cell receptor signaling. Additionally, mice lacking IRF4 in infected cells show a significant defect in virus reactivation, thereby identifying IRF4 as a crucial component of M2 mediated functions.
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Magor KE, Miranzo Navarro D, Barber MRW, Petkau K, Fleming-Canepa X, Blyth GAD, Blaine AH. Defense genes missing from the flight division. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2013; 41:377-88. [PMID: 23624185 PMCID: PMC7172724 DOI: 10.1016/j.dci.2013.04.010] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 04/16/2013] [Indexed: 05/12/2023]
Abstract
Birds have a smaller repertoire of immune genes than mammals. In our efforts to study antiviral responses to influenza in avian hosts, we have noted key genes that appear to be missing. As a result, we speculate that birds have impaired detection of viruses and intracellular pathogens. Birds are missing TLR8, a detector for single-stranded RNA. Chickens also lack RIG-I, the intracellular detector for single-stranded viral RNA. Riplet, an activator for RIG-I, is also missing in chickens. IRF3, the nuclear activator of interferon-beta in the RIG-I pathway is missing in birds. Downstream of interferon (IFN) signaling, some of the antiviral effectors are missing, including ISG15, and ISG54 and ISG56 (IFITs). Birds have only three antibody isotypes and IgD is missing. Ducks, but not chickens, make an unusual truncated IgY antibody that is missing the Fc fragment. Chickens have an expanded family of LILR leukocyte receptor genes, called CHIR genes, with hundreds of members, including several that encode IgY Fc receptors. Intriguingly, LILR homologues appear to be missing in ducks, including these IgY Fc receptors. The truncated IgY in ducks, and the duplicated IgY receptor genes in chickens may both have resulted from selective pressure by a pathogen on IgY FcR interactions. Birds have a minimal MHC, and the TAP transport and presentation of peptides on MHC class I is constrained, limiting function. Perhaps removing some constraint, ducks appear to lack tapasin, a chaperone involved in loading peptides on MHC class I. Finally, the absence of lymphotoxin-alpha and beta may account for the observed lack of lymph nodes in birds. As illustrated by these examples, the picture that emerges is some impairment of immune response to viruses in birds, either a cause or consequence of the host-pathogen arms race and long evolutionary relationship of birds and RNA viruses.
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Cai Q, Banerjee S, Cervini A, Lu J, Hislop AD, Dzeng R, Robertson ES. IRF-4-mediated CIITA transcription is blocked by KSHV encoded LANA to inhibit MHC II presentation. PLoS Pathog 2013; 9:e1003751. [PMID: 24204280 PMCID: PMC3814934 DOI: 10.1371/journal.ppat.1003751] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 09/23/2013] [Indexed: 01/18/2023] Open
Abstract
Peptides presentation to T cells by MHC class II molecules is of importance in initiation of immune response to a pathogen. The level of MHC II expression directly influences T lymphocyte activation and is often targeted by various viruses. Kaposi's sarcoma-associated herpesvirus (KSHV) encoded LANA is known to evade MHC class I peptide processing, however, the effect of LANA on MHC class II remains unclear. Here, we report that LANA down-regulates MHC II expression and presentation by inhibiting the transcription of MHC II transactivator (CIITA) promoter pIII and pIV in a dose-dependent manner. Strikingly, although LANA knockdown efficiently disrupts the inhibition of CIITA transcripts from its pIII and pIV promoter region, the expression of HLA-DQβ but no other MHC II molecules was significantly restored. Moreover, we revealed that the presentation of HLA-DQβ enhanced by LANA knockdown did not help LANA-specific CD4+ T cell recognition of PEL cells, and the inhibition of CIITA by LANA is independent of IL-4 or IFN-γ signaling but dependent on the direct interaction of LANA with IRF-4 (an activator of both the pIII and pIV CIITA promoters). This interaction dramatically blocked the DNA-binding ability of IRF-4 on both pIII and pIV promoters. Thus, our data implies that LANA can evade MHC II presentation and suppress CIITA transcription to provide a unique strategy of KSHV escape from immune surveillance by cytotoxic T cells.
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Steinhagen F, McFarland AP, Rodriguez LG, Tewary P, Jarret A, Savan R, Klinman DM. IRF-5 and NF-κB p50 co-regulate IFN-β and IL-6 expression in TLR9-stimulated human plasmacytoid dendritic cells. Eur J Immunol 2013; 43:1896-906. [PMID: 23616277 PMCID: PMC6389267 DOI: 10.1002/eji.201242792] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 03/27/2013] [Accepted: 04/18/2013] [Indexed: 11/12/2022]
Abstract
Synthetic oligonucleotides (ODN) expressing CpG motifs mimic the ability of bacterial DNA to trigger the innate immune system via TLR9. Plasmacytoid dendritic cells (pDCs) make a critical contribution to the ensuing immune response. This work examines the induction of antiviral (IFN-β) and pro-inflammatory (IL-6) cytokines by CpG-stimulated human pDCs and the human CAL-1 pDC cell line. Results show that interferon regulatory factor-5 (IRF-5) and NF-κB p50 are key co-regulators of IFN-β and IL-6 expression following TLR9-mediated activation of human pDCs. The nuclear accumulation of IRF-1 was also observed, but this was a late event that was dependant on type 1 IFN and unrelated to the initiation of gene expression. IRF-8 was identified as a novel negative regulator of gene activation in CpG-stimulated pDCs. As variants of IRF-5 and IRF-8 were recently found to correlate with susceptibility to certain autoimmune diseases, these findings are relevant to our understanding of the pharmacologic effects of "K" ODN and the role of TLR9 ligation under physiologic, pathologic, and therapeutic conditions.
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81
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Abstract
T-follicular helper (Tfh) cells are a new subset of effector CD4(+) T cells that are specialized in helping B cells in the germinal center reaction. Tfh cells are distinct from other established CD4(+) T-cell lineages, Th1, Th2, Th17, and T-regulatory cells, in their gene expression profiles. Tfh cell differentiation results from a network of transcriptional regulation by a master transcriptional factor Bcl6 as well as IRF4, c-Maf, Batf, and STAT3/5. During Tfh cell ontogeny, increased CXCR5 expression directs activated T-cell migration to the follicles, and their interaction with B cells leads to Bcl6 upregulation, which helps establish effector and memory Tfh cell program. This review summarizes the recent progress in molecular mechanisms underlying Tfh differentiation and discusses the future perspectives for this important area of research.
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82
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Lazear HM, Lancaster A, Wilkins C, Suthar MS, Huang A, Vick SC, Clepper L, Thackray L, Brassil MM, Virgin HW, Nikolich-Zugich J, Moses AV, Gale M, Früh K, Diamond MS. IRF-3, IRF-5, and IRF-7 coordinately regulate the type I IFN response in myeloid dendritic cells downstream of MAVS signaling. PLoS Pathog 2013; 9:e1003118. [PMID: 23300459 PMCID: PMC3536698 DOI: 10.1371/journal.ppat.1003118] [Citation(s) in RCA: 228] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Accepted: 11/23/2012] [Indexed: 12/11/2022] Open
Abstract
Although the transcription factors IRF-3 and IRF-7 are considered master regulators of type I interferon (IFN) induction and IFN stimulated gene (ISG) expression, Irf3−/−×Irf7−/− double knockout (DKO) myeloid dendritic cells (mDC) produce relatively normal levels of IFN-β after viral infection. We generated Irf3−/−×Irf5−/−×Irf7−/− triple knockout (TKO) mice to test whether IRF-5 was the source of the residual induction of IFN-β and ISGs in mDCs. In pathogenesis studies with two unrelated positive-sense RNA viruses (West Nile virus (WNV) and murine norovirus), TKO mice succumbed at rates greater than DKO mice and equal to or approaching those of mice lacking the type I IFN receptor (Ifnar−/−). In ex vivo studies, after WNV infection or exposure to Toll-like receptor agonists, TKO mDCs failed to produce IFN-β or express ISGs. In contrast, this response was sustained in TKO macrophages following WNV infection. To define IRF-regulated gene signatures, we performed microarray analysis on WNV-infected mDC from wild type (WT), DKO, TKO, or Ifnar−/− mice, as well as from mice lacking the RIG-I like receptor adaptor protein MAVS. Whereas the gene induction pattern in DKO mDC was similar to WT cells, remarkably, almost no ISG induction was detected in TKO or Mavs−/− mDC. The relative equivalence of TKO and Mavs−/− responses suggested that MAVS dominantly regulates ISG induction in mDC. Moreover, we showed that MAVS-dependent induction of ISGs can occur through an IRF-5-dependent yet IRF-3 and IRF-7-independent pathway. Our results establish IRF-3, -5, and -7 as the key transcription factors responsible for mediating the type I IFN and ISG response in mDC during WNV infection and suggest a novel signaling link between MAVS and IRF-5. Host pathogen sensors, including those of the Toll-like receptor and RIG-I like receptor (RLR) families, detect viral infection in cells. Signaling through these receptors triggers expression of type I interferon (IFN) and IFN-stimulated genes (ISGs), in part through the IRF family of transcription factors. Previous studies with West Nile virus (WNV) showed that IRF-3 and IRF-7 control IFN expression in fibroblasts and neurons, whereas macrophages and myeloid dendritic cells (mDC) retained the ability to induce IFN-β without IRF-3 and IRF-7. In the current study, we generated Irf3−/−×Irf5−/−×Irf7−/− (TKO) mice to characterize the contributions of specific IRF transcription factors to IFN and ISG induction in response to WNV infection in cells and in mice. We found that induction of IFN and ISGs was largely abolished in TKO mDC, but sustained in TKO macrophages. Because IFN and ISG induction also was absent in mDC lacking MAVS, a key mediator of RLR signaling, our results suggest a novel signaling link between IRF-5 and MAVS. This study establishes the molecular pathways responsible for IFN induction in mDC and suggests a cross-talk between IRF-5 and RLR signaling pathways.
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83
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Jacobs SR, Gregory SM, West JA, Wollish AC, Bennett CL, Blackbourn DJ, Heise MT, Damania B. The viral interferon regulatory factors of kaposi's sarcoma-associated herpesvirus differ in their inhibition of interferon activation mediated by toll-like receptor 3. J Virol 2013; 87:798-806. [PMID: 23115281 PMCID: PMC3554052 DOI: 10.1128/jvi.01851-12] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 10/23/2012] [Indexed: 01/11/2023] Open
Abstract
Kaposi's sarcoma-associated herpesvirus (KSHV) infection is correlated with three human malignancies and can establish lifelong latent infection in multiple cell types within its human host. In order to establish and maintain infection, KSHV utilizes multiple mechanisms to evade the host immune response. One such mechanism is the expression of a family of genes with homology to cellular interferon (IFN) regulatory factors (IRFs), known as viral IRFs (vIRFs). We demonstrate here that KSHV vIRF1, -2, and -3 have a differential ability to block type I interferon signaling mediated by Toll-like receptor 3 (TLR3), a receptor we have previously shown to be activated upon KSHV infection. vIRF1, -2, and -3 inhibited TLR3-driven activation of IFN transcription reporters. However, only vIRF1 and vIRF2 inhibited increases in both IFN-β message and protein levels following TLR3 activation. The expression of vIRF1 and vIRF2 also allowed for increased replication of a virus known to activate TLR3 signaling. Furthermore, vIRF1 and vIRF2 may block TLR3-mediated signaling via different mechanisms. Altogether, this report indicates that vIRFs are able to block IFN mediated by TLRs but that each vIRF has a unique function and mechanism for blocking antiviral IFN responses.
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84
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Raifer H, Mahiny AJ, Bollig N, Petermann F, Hellhund A, Kellner K, Guralnik A, Reinhard K, Bothur E, Huber M, Bauer S, Löhning M, Kiss EA, Ganal SC, Diefenbach A, Korn T, Lohoff M. Unlike αβ T cells, γδ T cells, LTi cells and NKT cells do not require IRF4 for the production of IL-17A and IL-22. Eur J Immunol 2012; 42:3189-201. [PMID: 22961652 DOI: 10.1002/eji.201142155] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 08/07/2012] [Accepted: 09/03/2012] [Indexed: 12/15/2022]
Abstract
Apart from conventional CD4(+) Th17 cells, the cytokines IL-17A and IL-22 can also be produced by γδ T cells, NK cells and lymphoid tissue inducer (LTi) cells. Th17 cells develop from precursor cells after T-cell receptor stimulation in the presence of TGF-β, IL-6 and IL-23. In contrast, a subset of γδ T cells ("γδT17") is committed for fast IL-17 production already in the thymus; however, γδ T cells can also produce IL-17 after prolonged in vitro stimulation via their γδ T-cell receptor plus IL-23. Here, we show that γδ T-, LTi- and NKT cells differ extensively from Th17 cells in their signalling requirements for the generation of IL-17A and IL-22. While production of these cytokines by Th17 cells totally depends on the transcription factor interferon regulatory factor 4 (IRF4), IRF4 is irrelevant in the other cell types. As for γδ T cells, this finding pertains to both thymic commitment and prolonged in vitro culture. Furthermore, IL-17A-producing γδ T cells accumulate in the central nervous system of IRF4 deficient (Irf4(-/-)) mice during experimental autoimmune encephalomyelitis. IL-17A-producing WT and Irf4(-/-) γδ T cells equally express CCR6 and lack CD27. The underlying IRF4-independent pathway partially involves STAT3 during in vitro stimulation.
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MESH Headings
- Animals
- Central Nervous System/immunology
- Central Nervous System/metabolism
- Central Nervous System/pathology
- Encephalomyelitis, Autoimmune, Experimental
- Gene Expression Regulation/genetics
- Gene Expression Regulation/immunology
- Interferon Regulatory Factors/genetics
- Interferon Regulatory Factors/immunology
- Interferon Regulatory Factors/metabolism
- Interleukin-17/biosynthesis
- Interleukin-17/genetics
- Interleukin-17/immunology
- Interleukins/biosynthesis
- Interleukins/genetics
- Interleukins/immunology
- Mice
- Mice, Inbred BALB C
- Mice, Knockout
- Natural Killer T-Cells/immunology
- Natural Killer T-Cells/metabolism
- Natural Killer T-Cells/pathology
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Receptors, Antigen, T-Cell, gamma-delta/genetics
- Receptors, Antigen, T-Cell, gamma-delta/immunology
- Receptors, Antigen, T-Cell, gamma-delta/metabolism
- Receptors, CCR6/biosynthesis
- Receptors, CCR6/genetics
- Receptors, CCR6/immunology
- STAT3 Transcription Factor/genetics
- STAT3 Transcription Factor/immunology
- STAT3 Transcription Factor/metabolism
- Th17 Cells/immunology
- Th17 Cells/metabolism
- Th17 Cells/pathology
- Tumor Necrosis Factor Receptor Superfamily, Member 7/biosynthesis
- Tumor Necrosis Factor Receptor Superfamily, Member 7/genetics
- Tumor Necrosis Factor Receptor Superfamily, Member 7/immunology
- Interleukin-22
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85
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Nayar R, Enos M, Prince A, Shin H, Hemmers S, Jiang JK, Klein U, Thomas CJ, Berg LJ. TCR signaling via Tec kinase ITK and interferon regulatory factor 4 (IRF4) regulates CD8+ T-cell differentiation. Proc Natl Acad Sci U S A 2012; 109:E2794-802. [PMID: 23011795 PMCID: PMC3478592 DOI: 10.1073/pnas.1205742109] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
CD8(+) T-cell development in the thymus generates a predominant population of conventional naive cells, along with minor populations of "innate" T cells that resemble memory cells. Recent studies analyzing a variety of KO or knock-in mice have indicated that impairments in the T-cell receptor (TCR) signaling pathway produce increased numbers of innate CD8(+) T cells, characterized by their high expression of CD44, CD122, CXCR3, and the transcription factor, Eomesodermin (Eomes). One component of this altered development is a non-CD8(+) T cell-intrinsic role for IL-4. To determine whether reduced TCR signaling within the CD8(+) T cells might also contribute to this pathway, we investigated the role of the transcription factor, IFN regulatory factor 4 (IRF4). IRF4 is up-regulated following TCR stimulation in WT T cells; further, this up-regulation is impaired in T cells treated with a small-molecule inhibitor of the Tec family tyrosine kinase, IL-2 inducible T-cell kinase (ITK). In contrast to WT cells, activation of IRF4-deficient CD8(+) T cells leads to rapid and robust expression of Eomes, which is further enhanced by IL-4 stimulation. In addition, inhibition of ITK together with IL-4 increases Eomeso up-regulation. These data indicate that ITK signaling promotes IRF4 up-regulation following CD8(+) T-cell activation and that this signaling pathway normally suppresses Eomes expression, thereby regulating the differentiation pathway of CD8(+) T cells.
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MESH Headings
- Animals
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cells, Cultured
- Female
- Flow Cytometry
- Forkhead Transcription Factors/genetics
- Forkhead Transcription Factors/immunology
- Forkhead Transcription Factors/metabolism
- Gene Expression/drug effects
- Interferon Regulatory Factors/genetics
- Interferon Regulatory Factors/immunology
- Interferon Regulatory Factors/metabolism
- Interleukin-4/pharmacology
- Lymphocyte Activation/immunology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Protein-Tyrosine Kinases/genetics
- Protein-Tyrosine Kinases/immunology
- Protein-Tyrosine Kinases/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Signal Transduction/genetics
- Signal Transduction/immunology
- T-Box Domain Proteins/genetics
- T-Box Domain Proteins/immunology
- T-Box Domain Proteins/metabolism
- T-Lymphocytes, Regulatory/immunology
- T-Lymphocytes, Regulatory/metabolism
- Thymocytes/immunology
- Thymocytes/metabolism
- Thymus Gland/cytology
- Thymus Gland/immunology
- Thymus Gland/metabolism
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86
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Bathige SDNK, Whang I, Umasuthan N, Lim BS, Park MA, Kim E, Park HC, Lee J. Interferon regulatory factors 4 and 8 in rock bream, Oplegnathus fasciatus: structural and expressional evidence for their antimicrobial role in teleosts. FISH & SHELLFISH IMMUNOLOGY 2012; 33:857-871. [PMID: 22885028 DOI: 10.1016/j.fsi.2012.07.017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 07/09/2012] [Accepted: 07/27/2012] [Indexed: 06/01/2023]
Abstract
The interferon regulatory factor (IRF) members IRF4 and IRF8 contribute to B-lymphocyte development and can act as regulators of immunoglobulin (Ig) light chain gene transcription. These two IRFs are closely interrelated and are expressed at high levels in the lymphoid and myeloid cells of the immune system. In this study, the complete cDNA and genomic sequences of rock bream IRF4 (RbIRF4) and IRF8 (RbIRF8) were identified by homology screening of a multi-tissue normalized cDNA library and a BAC library, respectively, which had been established using Roche 454 GS-FLX™ technology. The full-length RbIRF4 cDNA is composed of 3442 bp and encodes a polypeptide of 462 amino acids; the genomic DNA is 9262 bp in length, consisting of eight exons and seven introns. The full-length RbIRF8 cDNA is composed of 2186 bp and encodes a 422 amino acid polypeptide; the genomic DNA is 4120 bp in length, consisting of nine exons and eight introns. The deduced amino acid sequences of RbIRF4 and RbIRF8 include a conserved DNA-binding domain (DBD) encompassing a tryptophan pentad-repeat and an IRF-association domain (IAD). Several putative transcription factor binding sites were also identified in 5' flanking region of both RbIRF4 and RbIRF8, and include those of immune-related factors. Quantitative real time PCR analysis of healthy rock bream detected the highest expression levels of RbIRF4 and RbIRF8 in lymphomyeloid-rich tissues. In addition, viral (rock bream iridovirus) and bacterial (Edwardsiella tarda and Streptococcus iniae) infection stimulated RbIRF4 and RbIRF8 expressions in head kidney and spleen. These results suggest not only that RbIRF4 and RbIRF8 may have a protective function against virus and bacteria pathogen invasion in rock bream, but also that IRFs may be immunomodulatory factors of teleost fish.
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87
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Josset L, Belser JA, Pantin-Jackwood MJ, Chang JH, Chang ST, Belisle SE, Tumpey TM, Katze MG. Implication of inflammatory macrophages, nuclear receptors, and interferon regulatory factors in increased virulence of pandemic 2009 H1N1 influenza A virus after host adaptation. J Virol 2012; 86:7192-206. [PMID: 22532695 PMCID: PMC3416346 DOI: 10.1128/jvi.00563-12] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 04/13/2012] [Indexed: 12/13/2022] Open
Abstract
While pandemic 2009 H1N1 influenza A viruses were responsible for numerous severe infections in humans, these viruses do not typically cause corresponding severe disease in mammalian models. However, the generation of a virulent 2009 H1N1 virus following serial lung passage in mice has allowed for the modeling of human lung pathology in this species. Genetic determinants of mouse-adapted 2009 H1N1 viral pathogenicity have been identified, but the molecular and signaling characteristics of the host response following infection with this adapted virus have not been described. Here we compared the gene expression response following infection of mice with A/CA/04/2009 (CA/04) or the virulent mouse-adapted strain (MA-CA/04). Microarray analysis revealed that increased pathogenicity of MA-CA/04 was associated with the following: (i) an early and sustained inflammatory and interferon response that could be driven in part by interferon regulatory factors (IRFs) and increased NF-κB activation, as well as inhibition of the negative regulator TRIM24, (ii) early and persistent infiltration of immune cells, including inflammatory macrophages, and (iii) the absence of activation of lipid metabolism later in infection, which may be mediated by inhibition of nuclear receptors, including PPARG and HNF1A and -4A, with proinflammatory consequences. Further investigation of these signatures in the host response to other H1N1 viruses of various pathogenicities confirmed their general relevance for virulence of influenza virus and suggested that lung response to MA-CA/04 virus was similar to that following infection with lethal H1N1 r1918 influenza virus. This study links differential activation of IRFs, nuclear receptors, and macrophage infiltration with influenza virulence in vivo.
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88
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Tian L, Humblet-Baron S, Liston A. Immune tolerance: are regulatory T cell subsets needed to explain suppression of autoimmunity? Bioessays 2012; 34:569-75. [PMID: 22419393 DOI: 10.1002/bies.201100180] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The potential for self-reactive T cells to cause autoimmune disease is held in check by Foxp3(+) regulatory T cells (Tregs), essential mediators of peripheral immunological tolerance. Tregs have the capacity to suppress multiple branches of the immune system, tightly controlling the different subsets of effector T cells across multiple different tissue environments. Recent genetic experiments have found mutations that disrupt specific Treg: effector T cell relationships, leading to the possibility that subsets of Tregs are required to suppress each subset of effector T cells. Here we review the environmental factors and mechanisms that allow Tregs to suppress specific subsets of effector T cells, and find that a parsimonious explanation of the genetic data can be made without invoking Treg subsets. Instead, Tregs show a functional and chemotactic plasticity based on microenvironmental influences that allows the common pool of cells to suppress multiple distinct immune responses.
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89
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Bollig N, Brüstle A, Kellner K, Ackermann W, Abass E, Raifer H, Camara B, Brendel C, Giel G, Bothur E, Huber M, Paul C, Elli A, Kroczek RA, Nurieva R, Dong C, Jacob R, Mak TW, Lohoff M. Transcription factor IRF4 determines germinal center formation through follicular T-helper cell differentiation. Proc Natl Acad Sci U S A 2012; 109:8664-9. [PMID: 22552227 PMCID: PMC3365194 DOI: 10.1073/pnas.1205834109] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Follicular T-helper (T(FH)) cells cooperate with GL7(+)CD95(+) germinal center (GC) B cells to induce antibody maturation. Herein, we identify the transcription factor IRF4 as a T-cell intrinsic precondition for T(FH) cell differentiation and GC formation. After immunization with protein or infection with the protozoon Leishmania major, draining lymph nodes (LNs) of IFN-regulatory factor-4 (Irf4(-/-)) mice lacked GCs and GC B cells despite developing normal initial hyperplasia. GCs were also absent in Peyer's patches of naive Irf4(-/-) mice. Accordingly, CD4(+) T cells within the LNs and Peyer's patches failed to express the T(FH) key transcription factor B-cell lymphoma-6 and other T(FH)-related molecules. During chronic leishmaniasis, the draining Irf4(-/-) LNs disappeared because of massive cell death. Adoptive transfer of WT CD4(+) T cells or few L. major primed WT T(FH) cells reconstituted GC formation, GC B-cell differentiation, and LN cell survival. In support of a T-cell intrinsic IRF4 activity, Irf4(-/-) T(FH) cell differentiation was not rescued by close neighborhood to transferred WT T(FH) cells. Together with its known B lineage-specific roles during plasma cell maturation and class switch, our study places IRF4 in the center of antibody production toward T-cell-dependent antigens.
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90
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Liu MQ, Zhou DJ, Wang X, Zhou W, Ye L, Li JL, Wang YZ, Ho WZ. IFN-λ3 inhibits HIV infection of macrophages through the JAK-STAT pathway. PLoS One 2012; 7:e35902. [PMID: 22558263 PMCID: PMC3338759 DOI: 10.1371/journal.pone.0035902] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2011] [Accepted: 03/23/2012] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Interferon lambda 3 (IFN-λ3) is a newly identified cytokine with antiviral activity, and its single nucleotide polymorphisms are strongly associated with the treatment effectiveness and development of chronic hepatitis C virus infection. We thus examined the potential of IFN-λ3 to inhibit HIV replication and the possible mechanisms of the anti-HIV action by IFN-λ3 in human macrophages. PRINCIPAL FINDINGS Under different conditions (before, during, and after HIV infection), IFN-λ3 significantly inhibited viral replication in macrophages, which was associated with the induction of multiple antiviral cellular factors (ISG56, MxA, OAS-1, A3G/F and tetherin) and IFN regulatory factors (IRF-1, 3, 5, 7 and 9). This anti-HIV action of IFN-λ3 could be compromised by the JAK-STAT inhibitor. In addition, IFN-λ3 treatment of macrophages induced the expression of toll-like receptor 3 (TLR3) and two key adaptors (MyD88 and TRIF) in type I IFN pathway activation. However, HIV infection compromised IFN-λ3-mediated induction of the key elements in JAK-STAT signaling pathway. CONCLUSIONS These data indicate that IFN-λ3 exerts its anti-HIV function by activating JAK-STAT pathway-mediated innate immunity in macrophages. Future in vivo studies are necessary in order to explore the potential for developing IFN-λ3-based therapy for HIV disease.
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MESH Headings
- Adaptor Proteins, Vesicular Transport/genetics
- Adaptor Proteins, Vesicular Transport/immunology
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/immunology
- Cells, Cultured
- Gene Expression Regulation/drug effects
- HIV-1/drug effects
- HIV-1/physiology
- Humans
- Immunity, Innate
- Interferon Regulatory Factors/genetics
- Interferon Regulatory Factors/immunology
- Interferons
- Interleukins/immunology
- Interleukins/pharmacology
- Janus Kinases/antagonists & inhibitors
- Janus Kinases/genetics
- Janus Kinases/immunology
- Macrophages/drug effects
- Macrophages/immunology
- Macrophages/virology
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/immunology
- Phosphorylation
- Protein Kinase Inhibitors/pharmacology
- Receptors, Interleukin-1/genetics
- Receptors, Interleukin-1/immunology
- STAT Transcription Factors/genetics
- STAT Transcription Factors/immunology
- Signal Transduction/drug effects
- Toll-Like Receptor 3/genetics
- Toll-Like Receptor 3/immunology
- Virus Replication/drug effects
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91
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Rubio CA. Detecting plasma cell precursors in autoimmune hepatitis. In Vivo 2012; 26:319-321. [PMID: 22351677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
BACKGROUND Autoimmune hepatitis (AIH) is a non-resolving inflammatory liver disease. Inflammation showing plasma cells under hematoxylin-eosin (H&E) stain is typical of AIH. In many cases, however, only lymphocytes and occasional granulocytes are found. It was recently noticed that the antibody to multiple myeloma oncogene 1/IRF4 (MUM1), stained plasma cells and their precursors. PATIENTS AND METHODS Liver biopsies from 11 patients were stained with H&E and with anti-MUM1. Clinically, four patients were suspicious of AIH, four had viral hepatitis C, two nonalcoholic steatohepatitis (NASH) and one, fatty liver. Counting was performed in three high-power fields. RESULTS In patients having clinical suspicion of AIH, H&E revealed plasma cells in only one of the four cases. On the other hand, MUM1 immunostain revealed such cells in all four cases, MUM1-expressing cells were found in the portal triads, in the zone corresponding to interface inflammation and in the parenchyma surrounding the interface hepatitis. MUM 1-expressing cells ranged from 26 to 44 in AIH, from 2 to 15 in viral hepatitis C, from 1 to 3 in NASH, and from 0 to 2 in the case with fatty liver (AIH vs. viral hepatitis C/NAS/fatty liver, p<0.05). CONCLUSION These preliminary results suggest that MUM1 immunostain may be of help in endorsing a presumptive clinical diagnosis of AIH and may add valuable information in the differential diagnosis between AIH and the other liver diseases examined here. This appears to be the first report in which MUM1 immunostain has been applied to assess the presence of plasma cell precursors in AIH.
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92
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Xia J, Hu GB, Dong XZ, Liu QM, Zhang SC. Molecular characterization and expression analysis of interferon regulatory factor 5 (IRF-5) in turbot, Scophthalmus maximus. FISH & SHELLFISH IMMUNOLOGY 2012; 32:211-218. [PMID: 22062122 DOI: 10.1016/j.fsi.2011.10.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Revised: 10/19/2011] [Accepted: 10/19/2011] [Indexed: 05/31/2023]
Abstract
Interferon regulatory factor 5 (IRF-5) plays a role both in the antiviral and inflammatory responses. In this study, we described the structure, mRNA tissue distribution and regulation of an IRF-5 gene from turbot, Scophthalmus maximus (SmIRF-5). The gene sequence of SmIRF-5 is 4275 bp long, composed of 9 exons and 8 introns similar to known IRF-5 genes of vertebrates, and encodes a peptide of 487 amino acids. The deduced protein sequence shares the highest identity of ∼60-70% with fish IRF-5 and possesses a DNA-binding domain (DBD), a middle region (MR), an IRF association domain (IAD) and a virus activated domain (VAD) known to be important for the functions of IRF-5 in mammals. Phylogenetic analysis grouped SmIRF-5 with other IRF-5s of vertebrates. SmIRF-5 transcripts were detectable in a wide range of tissue types of healthy fish with higher levels observed in the head kidney, kidney and spleen. The SmIRF-5 was transcriptionally up-regulated by turbot reddish body iridovirus (TRBIV) but not by polyinosinic:polycytidylic acid (poly I:C) in the gills, head kidney, spleen and muscle. Both the highest inducibility and earliest induction of SmIRF-5 expression were observed in the spleen where it reached a maximum level at day 1 after infection, prior to that of turbot Mx. These findings may help to better understand the roles of SmIRF-5 in antiviral response.
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93
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Xiaoni G, Zhuo C, Xuzhen W, Dengqiang W, Xinwen C. Molecular cloning and characterization of interferon regulatory factor 1 (IRF-1), IRF-2 and IRF-5 in the chondrostean paddlefish Polyodon spathula and their phylogenetic importance in the Osteichthyes. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2012; 36:74-84. [PMID: 21703300 DOI: 10.1016/j.dci.2011.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 06/06/2011] [Accepted: 06/07/2011] [Indexed: 05/31/2023]
Abstract
The interferon regulatory factor (IRF) with its 10 members is a very important gene family related to innate immunity. Currently, most fish IRFs reported are from bony fish (teleosts). Cloning and sequencing of IRFs from chondrosteans, the so-called "ancient fish" including sturgeon, paddlefish, bichir and gar, are absent from the literature. In this study, three IRF genes PsIRF-1, PsIRF-2 and PsIRF-5, were cloned and characterized from the paddlefish (Polyodon spathula). PsIRF-1 includes an open reading frame (ORF) of 972 bp that encodes a putative protein of 324 amino acids; PsIRF-2 includes an ORF of 1023 bp encoding 341 amino acids and PsIRF-5 includes an ORF of 1491 bp that encodes 497 amino acids. The PsIRF-5 gene structure is similar to those in mammals but differs from those in teleosts in the first and second exons. Phylogenetic studies of the putative amino acid sequences of PsIRF-1, PsIRF-2 and PsIRF-5 based on the neighbor-joining and Bayesian inference method for Osteichthyes found widely accepted inter-relationships among actinopterygians and tetrapods. Reverse Transcription Polymerase Chain Reaction (RT-PCR) analysis of PsIRF-1, PsIRF-2 and PsIRF-5 in different paddlefish tissues shows higher levels of expression in gill, spleen and head kidney. Poly (I: C) (polyinosinic-polycytidylic acid) stimulation in vivo up-regulated PsIRF-1 and PsIRF-2 expression, while PsIRF-5 gene expression did not respond to the challenge of Poly (I: C).
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94
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Ivashkiv LB. Inflammatory signaling in macrophages: transitions from acute to tolerant and alternative activation states. Eur J Immunol 2011; 41:2477-81. [PMID: 21952800 PMCID: PMC3264328 DOI: 10.1002/eji.201141783] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Acute inflammatory activation of macrophages by Toll-like and related receptors is characterized by transient activation of MAPK-, NF-κB- and IRF-mediated signaling pathways and expression of pro-inflammatory genes. This activation state is inherently unstable and often transitions into a state of 'tolerance' characterized by diminished signaling, repressive chromatin modifications, and an alternative gene expression program. This Viewpoint describes signaling and epigenetic mechanisms associated with transition to tolerant states, which are proposed to correspond to alternative activation states programmed by the original inflammatory stimuli.
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95
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Pan HF, Leng RX, Ye DQ. New evidence for the role of interferon regulatory factor 5 in the development of systemic lupus erythematosus: comment on the article by Tada et al. ARTHRITIS AND RHEUMATISM 2011; 63:2543. [PMID: 21437872 DOI: 10.1002/art.30359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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96
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Marquis JF, Kapoustina O, Langlais D, Ruddy R, Dufour CR, Kim BH, MacMicking JD, Giguère V, Gros P. Interferon regulatory factor 8 regulates pathways for antigen presentation in myeloid cells and during tuberculosis. PLoS Genet 2011; 7:e1002097. [PMID: 21731497 PMCID: PMC3121741 DOI: 10.1371/journal.pgen.1002097] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 04/04/2011] [Indexed: 12/15/2022] Open
Abstract
IRF8 (Interferon Regulatory Factor 8) plays an important role in defenses against intracellular pathogens, including several aspects of myeloid cells function. It is required for ontogeny and maturation of macrophages and dendritic cells, for activation of anti-microbial defenses, and for production of the Th1-polarizing cytokine interleukin-12 (IL-12) in response to interferon gamma (IFNγ) and protection against infection with Mycobacterium tuberculosis. The transcriptional programs and cellular pathways that are regulated by IRF8 in response to IFNγ and that are important for defenses against M. tuberculosis are poorly understood. These were investigated by transcript profiling and chromatin immunoprecipitation on microarrays (ChIP-chip). Studies in primary macrophages identified 368 genes that are regulated by IRF8 in response to IFNγ/CpG and that behave as stably segregating expression signatures (eQTLs) in F2 mice fixed for a wild-type or mutant allele at IRF8. A total of 319 IRF8 binding sites were identified on promoters genome-wide (ChIP-chip) in macrophages treated with IFNγ/CpG, defining a functional G/AGAAnTGAAA motif. An analysis of the genes bearing a functional IRF8 binding site, and showing regulation by IFNγ/CpG in macrophages and/or in M. tuberculosis-infected lungs, revealed a striking enrichment for the pathways of antigen processing and presentation, including multiple structural and enzymatic components of the Class I and Class II MHC (major histocompatibility complex) antigen presentation machinery. Also significantly enriched as IRF8 targets are the group of endomembrane- and phagosome-associated small GTPases of the IRG (immunity-related GTPases) and GBP (guanylate binding proteins) families. These results identify IRF8 as a key regulator of early response pathways in myeloid cells, including phagosome maturation, antigen processing, and antigen presentation by myeloid cells. IRF8 is a member of the Interferon Regulatory Factor family that is expressed in myeloid cells such as macrophages and dendritic cells and that activates or represses gene transcription upon stimulation with interferon gamma (IFNγ), lipopolysaccharide (LPS), and other microbial stimuli. IRF8 plays an important role in several aspects of myeloid cells, including differentiation and maturation of early progenitor cells, expression of intrinsic anti-microbial defenses, and production of the interleukin-12 (IL12) cytokine, which is essential for priming of early T cell– mediated immune response. IRF8 mutant mice are susceptible to a number of intracellular infections including pulmonary tuberculosis. The transcriptional and cellular pathways regulated by IRF8 and essential for resistance to infections were studied by a combination of genome-wide methods, including transcriptional profiling and chromatin immunoprecipitation (ChIP-chip). These studies identified phagosome maturation, antigen processing, and antigen presentation as critical pathways in early host–pathogen interactions regulated by IRF8 in macrophages exposed to IFNγ/CpG and in lung tissues infected with Mycobacterium tuberculosis.
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97
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Transcription factor presents new target for rheumatoid arthritis therapy. Immunotherapy 2011; 3:311. [PMID: 21516879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023] Open
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98
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Holodick NE, Tumang JR, Rothstein TL. Immunoglobulin secretion by B1 cells: differential intensity and IRF4-dependence of spontaneous IgM secretion by peritoneal and splenic B1 cells. Eur J Immunol 2010; 40:3007-16. [PMID: 21061433 PMCID: PMC3139744 DOI: 10.1002/eji.201040545] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 07/09/2010] [Accepted: 08/16/2010] [Indexed: 12/25/2022]
Abstract
Peritoneal B1 cells are typified by spontaneous, constitutive secretion of IgM natural antibody, detected by ELISPOT assay, among other means. Recently, this key characteristic has been called into question, a reason for which we evaluated the integrity of IgM(+) ELISPOT spots. We found that fixed B1 cells fail to produce ELISPOT spots, that interference with Golgi function inhibits ELISPOT spot formation, and that B1 cell-derived immunoglobulin in supernatant samples is EndoH-resistant. These findings indicate that spots produced by B1 cells on ELISPOT assay reflect secretory IgM actively exported by viable B1 cells. Current paradigms propose that interferon response factor 4 (IRF4) is required for plasma cell differentiation and immunoglobulin secretion. However, we found that IgM secretion by peritoneal B1 cells is not altered in IRF4-null mice. In contrast, spontaneous IgM secretion by splenic B1 cells, which amounts to much more IgM secreted per cell, is dramatically reduced in the absence of IRF4. These results indicate that peritoneal B1 cells spontaneously secrete low levels of IgM via an IRF4-independent non-classical pathway, and, considering the low level of serum IgM in IRF-null mice, further suggest that accumulation of serum immunoglobulin depends on IRF4-dependent secretion by splenic B1 cells.
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99
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Biswas PS, Gupta S, Chang E, Song L, Stirzaker RA, Liao JK, Bhagat G, Pernis AB. Phosphorylation of IRF4 by ROCK2 regulates IL-17 and IL-21 production and the development of autoimmunity in mice. J Clin Invest 2010; 120:3280-95. [PMID: 20697158 PMCID: PMC2929726 DOI: 10.1172/jci42856] [Citation(s) in RCA: 184] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Accepted: 06/30/2010] [Indexed: 12/25/2022] Open
Abstract
Deregulated production of IL-17 and IL-21 plays a key pathogenic role in many autoimmune disorders. A delineation of the mechanisms that underlie the inappropriate synthesis of IL-17 and IL-21 in autoimmune diseases can thus provide important insights into potential therapies for these disorders. Here we have shown that the serine-threonine kinase Rho-associated, coiled-coil-containing protein kinase 2 (ROCK2) becomes activated in mouse T cells under Th17 skewing conditions and phosphorylates interferon regulatory factor 4 (IRF4), a transcription factor that is absolutely required for the production of IL-17 and IL-21. We furthermore demonstrated that ROCK2-mediated phosphorylation of IRF4 regulated the synthesis of IL-17 and IL-21 and the differentiation of Th17 cells. Whereas CD4+ T cells from WT mice activated ROCK2 physiologically under Th17 conditions, CD4+ T cells from 2 different mouse models of spontaneous autoimmunity aberrantly activated ROCK2 under neutral conditions. Moreover, administration of ROCK inhibitors ameliorated the deregulated production of IL-17 and IL-21 and the inflammatory and autoantibody responses observed in these autoimmune mice. Our findings thus uncover a crucial link among ROCK2, IRF4, and the production of IL-17 and IL-21 and support the idea that selective inhibition of ROCK2 could represent an important therapeutic regimen for the treatment of autoimmune disorders.
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100
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Vitali P, Scadden ADJ. Double-stranded RNAs containing multiple IU pairs are sufficient to suppress interferon induction and apoptosis. Nat Struct Mol Biol 2010; 17:1043-50. [PMID: 20694008 PMCID: PMC2935675 DOI: 10.1038/nsmb.1864] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 06/08/2010] [Indexed: 12/24/2022]
Abstract
Adenosine deaminases acting on RNA (ADARs) catalyze hyperediting of long double-stranded RNAs (dsRNAs), whereby up to 50% of adenosines are converted to inosine (I). Although hyperedited dsRNAs (IU-dsRNAs) have been implicated in various cellular functions, we now provide evidence for another role. We show that IU-dsRNA suppresses the induction of interferon-stimulated genes (ISGs) and apoptosis by poly(IC). Moreover, we show that IU-dsRNA inhibits the activation of interferon regulatory factor 3 (IRF3), which is essential for the induction of ISGs and apoptosis. Finally, we speculate that the inhibition of IRF3 results from specific binding of IU-dsRNA to MDA-5 or RIG-I, both of which are cytosolic sensors for poly(IC). Although our data are consistent with a previous study in which ADAR1 deletion resulted in increased expression of ISGs and apoptosis, we show that IU-dsRNA per se suppresses ISGs and apoptosis. We therefore propose that any IU-dsRNA generated by ADAR1 can inhibit both pathways.
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