Thomas Decker | University of Vienna (original) (raw)

Papers by Thomas Decker

Scientific Reports

Intracellular bacteria produce antigens, which serve as potent activators of γδ T cells. Phosphoa... more Intracellular bacteria produce antigens, which serve as potent activators of γδ T cells. Phosphoantigens are presented via a complex of butyrophilins (BTN) to signal infection to human Vγ9+Vδ2+ T cells. Here, we established an in vitro system allowing for studies of Vγ9+Vδ2+ T cell activity in coculture with epithelial cells infected with the intracellular bacterial pathogen Listeria monocytogenes. We report that the Vγ9+Vδ2+ T cells efficiently control L. monocytogenes growth in such cultures. This effector function requires the expression of members of the BTN3A family on epithelial cells. Specifically, we observed a BTN3A1-independent BTN3A3 activity to present antigen to Vγ9+Vδ2+ T cells. Since BTN3A1 is the only BTN3A associated with phosphoantigen presentation, our study suggests that BTN3A3 may present different classes of antigens to mediate Vγ9+Vδ2+ T cell effector function against L. monocytogenes-infected epithelia.

Molecular and Cellular Biology, 1995

Gamma interferon (IFN-gamma), a macrophage-activating cytokine, modulates gene expression through... more Gamma interferon (IFN-gamma), a macrophage-activating cytokine, modulates gene expression through the activity of a transcription factor designated IFN-gamma activation factor (GAF). GAF is formed after phosphorylation on tyrosine and dimerization of the 91-kDa protein STAT1. We have recently reported that differentiation of the promonocytic cell line U937 into monocytes increases the amount of cellular GAF after IFN-gamma treatment and at the same time increases the phosphorylation of STAT1. Here we show that activation of the JAK family kinases, which are instrumental in mediating STAT1 phosphorylation on tyrosine, did not increase upon monocytic U937 differentiation. Consistent with this finding, levels of STAT1 tyrosine phosphorylation were virtually identical in promonocytic and monocytic U937 cells. Analysis of STAT1 phosphoamino acids and mapping of phosphopeptides showed an IFN-gamma-dependent increase in Ser phosphorylation in differentiated cells. Analyses of STAT1 isoform...

Molecular and Cellular Biology, 1996

Tyrosine phosphorylation and activation of the transcription factor Stat5 occur in response to st... more Tyrosine phosphorylation and activation of the transcription factor Stat5 occur in response to stimuli like granulocyte-macrophage colony-stimulating factor, interleukin-3, or erythropoietin that stimulate both proliferation and differentiation of hematopoietic cells. It is unclear whether Stat5 is part of a proliferative response or part of the events leading to cellular differentiation. Here we report that agents promoting differentiation but not proliferation of hematopoietic cells, like phorbol ester or both types of interferons (IFNs), activate Stat5 in promonocytic U937 cells. Both IFN types caused tyrosine phosphorylation and DNA binding of predominantly one Stat5 isoform (Stat5a) despite expression of both Stat5a and Stat5b proteins. Monocytic differentiation of U937 cells led to a strong decrease in IFN-gamma-mediated activation of Stat5 but not of Stat1. Transactivation of Stat5-target genes occurred in response to IFN-gamma, which activates both Stat5 and Stat1, but not i...

The Journal of Immunology, 2002

Type I IFNs (IFN-α/β) modulate innate immune responses. Here we show activation of transcription ... more Type I IFNs (IFN-α/β) modulate innate immune responses. Here we show activation of transcription factor IFN regulatory factor 3, the synthesis of large amounts of IFN-β mRNA, and type I IFN signal transduction in macrophages infected with Listeria monocytogenes. Expression of the bacterial virulence protein listeriolysin O was necessary, but not sufficient, for efficient IFN-β production. Signaling through a pathway involving the type I IFN receptor and Stat1 sensitized macrophages to L. monocytogenes-induced cell death in a manner not requiring inducible NO synthase (nitric oxide synthase 2) or protein kinase R, potential effectors of type I IFN action during microbial infections. The data stress the importance of type I IFN for the course of infections with intracellular bacteria and suggest that factors other than listeriolysin O contribute to macrophage death during Listeria infection.

activation in macrophages. phosphorylation of STAT1 promotes GAF Differentiation-regulated serine

Journal of Experimental Medicine, 2021

Interferons establish innate antiviral immunity. Two recent papers in JEM by Lopez et al. (2021. ... more Interferons establish innate antiviral immunity. Two recent papers in JEM by Lopez et al. (2021. J. Exp. Med.https://doi.org/10.1084/jem.20211211) and Cheemarla et al. (2021. J. Exp. Med.https://doi.org/10.1084/jem.20210583) show that an appropriate supply of antiviral interferon enables epithelial cells of the nasopharyngeal mucosa to inhibit SARS-CoV-2 growth and that interferon-induced mucosal genes serve as biomarkers of infection.

Engagement of macrophages in innate immune responses is directed and enhanced by type I and type ... more Engagement of macrophages in innate immune responses is directed and enhanced by type I and type II interferons. An essential component of IFN activity is the use of JAK-STAT signal transduction for the transcriptional control of interferon-stimulated genes (ISG). Here, we study the immediate early nuclear response to type I IFN and IFN-γ in murine macrophages. Despite their distinct immunological activities, both IFN types triggered highly overlapping epigenomic and transcriptional changes. These changes included a rapid rearrangement of the 3D chromatin organization and an increase of DNA accessibility at ISG loci. ISGF3, the major transcriptional regulator of ISG, controlled homeostatic as well as induced-state DNA accessibility at a subset of ISG. Increases in DNA accessibility correlated with the appearance of activating histone marks at surrounding nucleosomes. Collectively our data emphasize changes in the three-dimensional nuclear space and epigenome as an important facet of...

Listeria monocytogenes (L. monocytogenes) is a food-borne bacterial pathogen. Innate immunity to ... more Listeria monocytogenes (L. monocytogenes) is a food-borne bacterial pathogen. Innate immunity to L. monocytogenes is profoundly affected by type I interferons (IFN-I). Here we investigated host metabolism in L. monocytogenes-infected mice and its potential control by IFN-I. Accordingly, we used animals lacking either the IFN-I receptor (IFNAR) or IRF9, a subunit of ISGF3, the master regulator of IFN-I-induced genes. Transcriptomes and metabolite profiles showed that L. monocytogenes infection induces metabolic rewiring of the liver. This affects various metabolic pathways including fatty acid (FA) metabolism and oxidative phosphorylation and is partially dependent on IFN-I signaling. Livers and macrophages from Ifnar1-/- mice employ increased glutaminolysis in an IRF9-independent manner, possibly to readjust TCA metabolite levels due to reduced FA oxidation. Moreover, FA oxidation inhibition provides protection from L. monocytogenes infection, explaining part of the protection of Ir...

Nature Communications, 2019

Cells maintain the balance between homeostasis and inflammation by adapting and integrating the a... more Cells maintain the balance between homeostasis and inflammation by adapting and integrating the activity of intracellular signaling cascades, including the JAK-STAT pathway. Our understanding of how a tailored switch from homeostasis to a strong receptor-dependent response is coordinated remains limited. Here, we use an integrated transcriptomic and proteomic approach to analyze transcription-factor binding, gene expression and in vivo proximity-dependent labelling of proteins in living cells under homeostatic and interferon (IFN)-induced conditions. We show that interferons (IFN) switch murine macrophages from resting-state to induced gene expression by alternating subunits of transcription factor ISGF3. Whereas preformed STAT2-IRF9 complexes control basal expression of IFN-induced genes (ISG), both type I IFN and IFN-γ cause promoter binding of a complete ISGF3 complex containing STAT1, STAT2 and IRF9. In contrast to the dogmatic view of ISGF3 formation in the cytoplasm, our results suggest a model wherein the assembly of the ISGF3 complex occurs on DNA.

Cells maintain the balance between homeostasis and inflammation by adapting and integrating the a... more Cells maintain the balance between homeostasis and inflammation by adapting and integrating the activity of intracellular signalling cascades, including the JAK-STAT pathway. Our understanding how a tailored switch from homeostasis to a strong receptor-dependent response is coordinated remains limited. We used an integrated transcriptomic and proteomic approach to analyze transcription-factor binding, gene expression and in vivo proximity-dependent labelling of proteins in living cells under homeostatic and interferon (IFN)-induced conditions. We show that interferons (IFN) switch murine macrophages from resting-state to induced gene expression by alternating subunits of transcription factor ISGF3. Whereas preformed STAT2-IRF9 complexes control basal expression of IFN-induced genes (ISG), both type I IFN and, unexpectedly, IFNγ cause promoter binding of a complete ISGF3 complex containing STAT1, STAT2 and IRF9. In contrast to the dogmatic view of ISGF3 formation in the cytoplasm, ou...

Blood, Jan 16, 2018

Inhibition of Janus-kinase 1/2 (JAK1/2) is a mainstay to treat myeloproliferative neoplasms (MPN)... more Inhibition of Janus-kinase 1/2 (JAK1/2) is a mainstay to treat myeloproliferative neoplasms (MPN). Sporadic observations reported the co-incidence of B-cell non-Hodgkin lymphomas during treatment of MPN with JAK1/2 inhibitors. We assessed 626 patients with MPN, including 69 with myelofibrosis receiving JAK1/2 inhibitors for lymphoma development. B-cell lymphomas evolved in 4 (5.8%) of 69 patients receiving JAK1/2 inhibition compared with 2 (0.36%) of 557 with conventional treatment (16-fold increased risk). A similar 15-fold increase was observed in an independent cohort of 929 patients with MPN. Considering primary myelofibrosis only (N = 216), 3 lymphomas were observed in 31 inhibitor-treated patients (9.7%) vs 1 (0.54%) of 185 control patients. Lymphomas were of aggressive B-cell type, extranodal, or leukemic with high MYC expression in the absence of V617F or other MPN-associated mutations. Median time from initiation of inhibitor therapy to lymphoma diagnosis was 25 months. Clo...

PLoS Pathogens, 2012

Signal transducer and activator of transcription 1 (Stat1) is a key player in responses to interf... more Signal transducer and activator of transcription 1 (Stat1) is a key player in responses to interferons (IFN). Mutations of Stat1 cause severe immune deficiencies in humans and mice. Here we investigate the importance of Stat1 signaling for the innate and secondary immune response to the intracellular bacterial pathogen Listeria monocytogenes (Lm). Cell type-restricted ablation of the Stat1 gene in naïve animals revealed unique roles in three cell types: macrophage Stat1 signaling protected against lethal Lm infection, whereas Stat1 ablation in dendritic cells (DC) did not affect survival. T lymphocyte Stat1 reduced survival. Type I IFN (IFN-I) signaling in T lymphocytes reportedly weakens innate resistance to Lm. Surprisingly, the effect of Stat1 signaling was much more pronounced, indicating a contribution of Stat1 to pathways other than the IFN-I pathway. In stark contrast, Stat1 activity in both DC and T cells contributed positively to secondary immune responses against Lm in immunized animals, while macrophage Stat1 was dispensable. Our findings provide the first genetic evidence that Stat1 signaling in different cell types produces antagonistic effects on innate protection against Lm that are obscured in mice with complete Stat1 deficiency. They further demonstrate a drastic change in the cell type-dependent Stat1 requirement for memory responses to Lm infection.

PLoS Pathogens, 2009

Production of type I interferons (IFN-I, mainly IFNa and IFNb) is a hallmark of innate immune res... more Production of type I interferons (IFN-I, mainly IFNa and IFNb) is a hallmark of innate immune responses to all classes of pathogens. When viral infection spreads to lymphoid organs, the majority of systemic IFN-I is produced by a specialized ''interferon-producing cell'' (IPC) that has been shown to belong to the lineage of plasmacytoid dendritic cells (pDC). It is unclear whether production of systemic IFN-I is generally attributable to pDC irrespective of the nature of the infecting pathogen. We have addressed this question by studying infections of mice with the intracellular bacterium Listeria monocytogenes. Protective innate immunity against this pathogen is weakened by IFN-I activity. In mice infected with L. monocytogenes, systemic IFN-I was amplified via IFN-b, the IFN-I receptor (IFNAR), and transcription factor interferon regulatory factor 7 (IRF7), a molecular circuitry usually characteristic of non-pDC producers. Synthesis of serum IFN-I did not require TLR9. In contrast, in vitro-differentiated pDC infected with L. monocytogenes needed TLR9 to transcribe IFN-I mRNA. Consistent with the assumption that pDC are not the producers of systemic IFN-I, conditional ablation of the IFN-I receptor in mice showed that most systemic IFN-I is produced by myeloid cells. Furthermore, results obtained with FACS-purified splenic cell populations from infected mice confirmed the assumption that a cell type with surface antigens characteristic of macrophages and not of pDC is responsible for bulk IFN-I synthesis. The amount of IFN-I produced in the investigated mouse lines was inversely correlated to the resistance to lethal infection. Based on these data, we propose that the engagement of pDC, the mode of IFN-I mobilization, as well as the shaping of the antimicrobial innate immune response by IFN-I differ between intracellular pathogens.

Nature Immunology, 2003

Toll-like receptor-4 activation by lipopolysaccharide (LPS) induces the expression of interferon-... more Toll-like receptor-4 activation by lipopolysaccharide (LPS) induces the expression of interferon-β (IFN-β) in a MyD88-independent manner. Here we report that mice devoid of the JAK protein tyrosine kinase family member,Tyk2, were resistant to shock induced by high doses of LPS. Basal and LPS-induced expression of IFN-β and IFN-α4 mRNA in Tyk2-null macrophages were diminished. However, Tyk2-null mice showed normal systemic production of nitric oxide and proinflammatory cytokines and the in vivo response to tumor necrosis factor (TNF) was unperturbed. IFN-β-null but not STAT1-null mice were also resistant to high dose LPS treatment. Together, these data suggest that Tyk2 and IFN-β are essential effectors in LPS induced lethality.

The Journal of Immunology, 2009

Phosphorylation of transcription factor STAT-1 on Y701 regulates subcellular localization whereas... more Phosphorylation of transcription factor STAT-1 on Y701 regulates subcellular localization whereas phosphorylation of the transactivating domain at S727 enhances transcriptional activity. In this study, we investigate the impact of STAT-1 and the importance of transactivating domain phosphorylation on the induction of peptide-specific CTL in presence of the TLR9-dependent immune adjuvant IC31. STAT-1 deficiency completely abolished CTL induction upon immunization, which was strongly reduced in animals carrying the mutation of the S727 phospho-acceptor site. A comparable reduction of CTL was found in mice lacking the type I IFN (IFN-I) receptor, whereas IFN-␥-deficient mice behaved like wild-type controls. This finding suggests that S727phosphorylated STAT-1 supports IFN-I-dependent induction of CTL. In adoptive transfer experiments, IFN-I-and S727-phosphorylated STAT-1 were critical for the activation and function of dendritic cells. Mice with a T cell-specific IFN-I receptor ablation did not show impaired CTL responses. Unlike the situation observed for CTL development S727-phosphorylated STAT-1 restrained proliferation of naive CD8 ؉ T cells both in vitro and following transfer into Rag-deficient mice. In summary, our data reveal a dual role of S727-phosphorylated STAT-1 for dendritic cell maturation as a prerequisite for the induction of CTL activity and for T cell autonomous control of activation-induced or homeostatic proliferation.

Journal of Clinical Investigation, 2002

Innate immune responses derive from the ability of cells to rapidly combat invading microorganism... more Innate immune responses derive from the ability of cells to rapidly combat invading microorganisms without the requirement for an antigen-specific adaptation. These mechanisms have evolved to recognize common microbe-associated molecular patterns and to interfere with conserved replication and survival strategies that support the propagation of microbial invaders. Here, we consider the contributions of one cytokine family, the IFNs, to these innate defense mechanisms. IFNs were first recognized for their ability to impede viral replication, a function that is indeed critical for host survival in response to viral infection. In addition, IFN signaling is now known to play key roles in defending the host from bacteria and other pathogens and to help integrate early, innate responses with later events mediated by the adaptive immune system. The two recognized types of IFN exhibit distinct immunological properties (1). In humans and mice, type I IFNs include a number of IFN-α subtypes and a single species of IFN-β. (The immunological impact of another type I IFN, IFN-ω, is poorly understood and will not be considered here). While type I IFNs can be produced by all cells under appropriate conditions, a subpopulation of immature dendritic cells (DCs) that will be described in more detail below stands out for the extent of its contribution to overall IFN production during infections. IFN-γ is a type II IFN and serves not only to induce antiviral function, but also to activate macrophages, which strengthens innate responses to unicellular microorganisms (2). Unlike the type I IFNs, IFN-γ is produced by a limited number of cell types: activated NK cells, activated Th1 cells, and, in the presence of IL-12 and IL-18, activated DCs and macrophages. Expression of IFN-γ by Th1 cells provides an important link by which the adaptive immune response reinforces macrophage-based innate immunity. JAK-STAT signaling in IFN responses A common property of both IFN types is to induce immediate transcriptional responses through a JAK-STAT signal transduction pathway (3). All type I IFNs bind to a class II cytokine receptor composed of IFN-α receptor 1 (IFNAR1) and IFNAR2 chains, which are associated with the Janus kinases (JAKs) TYK2 and JAK1, respectively. Ligand-bound, tyrosine-phosphorylated receptor complexes bind the SH2 domains of signal transducers and activators of transcription (STATs) 1 and 2, causing phosphorylation of the proteins on tyrosines 701 and 692, respectively. Interaction of STATs through reciprocal SH2 domain-phosphotyrosine binding results in formation of two distinct transcription factor complexes. ISGF3, a heteromeric complex consisting of STAT1 and STAT2 in association with a third protein, p48 or IRF9, associates specifically with and transactivates genes with interferon-stimulated response elements (ISRE) in their promoter or enhancer regions. A simpler complex, consisting solely of the STAT1 homodimer, is also active as a transcription factor and binds to different DNA sequences, termed IFN-γ-activated site (GAS) elements (Figure 1). The receptor for IFN-γ is structurally related to that for type I IFN. It consists of IFN-γ receptor 1 (IFNGR1) and IFNGR2 chains in association with JAK1 and JAK2 kinases. Once tyrosine-phosphorylated in the presence of ligand, it binds STAT1 and causes phosphorylation of Y701. STAT1 homodimers are formed, move to the nucleus, and regulate transcription of promoters containing GAS sequences (Figure 1; ref. 4). Recent evidence indicates that nuclear responses can be stimulated by IFN-γ in the absence of STAT1 (5), but the transcription factors mediating the STAT1-independent response remain to be identified. In addition, some genes are induced by IFN-γ only in the absence of STAT1, suggesting that this protein can also mediate transcriptional repression. Innate immunity to viruses Cells in culture respond to viruses by deploying a complex network of signaling molecules that initiate and then amplify the production of type I IFNs. At an early

Immunity, 2010

Transcriptional regulation of the Nos2 gene encoding inducible nitric oxide synthase (iNOS) requi... more Transcriptional regulation of the Nos2 gene encoding inducible nitric oxide synthase (iNOS) requires type I interferon (IFN-I) signaling and additional signals emanating from pattern recognition receptors. Here we showed sequential and cooperative contributions of the transcription factors ISGF3 (a complex containing STAT1, STAT2, and IRF9 subunits) and NF-kB to the transcriptional induction of the Nos2 gene in macrophages infected with the intracellular bacterial pathogen Listeria monocytogenes. NF-kB preceded ISGF3 at the Nos2 promoter and generated a transcriptional memory effect by depositing basal transcription factor TFIIH with the associated CDK7 kinase for serine 5 phosphorylation of the RNA polymerase II (pol II) carboxyterminal domain (CTD). Subsequent to TFIIH deposition by NF-kB, ISGF3 attracted the pol II enzyme and phosphorylation at CTD S5 occurred. Thus, STATs and NF-kB cooperate through pol II promoter recruitment and the phosphorylation of its CTD, respectively, as a prerequisite for productive elongation of iNOS mRNA.

FEBS Letters, 2006

The mitochondria-associated adapter protein MAVS (also called IPS-1, VISA or CARDIF, designated M... more The mitochondria-associated adapter protein MAVS (also called IPS-1, VISA or CARDIF, designated MAVS for reasons of simplicity in our manuscript) relays signals from cytoplasmic sensors of viral RNA to the IRF3 kinase complex and the interferon-b (IFN-b) gene. Using siRNA-mediated knockdown in macrophages we show that IFN-b synthesis in response to transfected, intracellular double-stranded RNA (dsRNA), a pathogen-associated molecular pattern of viruses, is decreased in absence of MAVS. By contrast, the Gram-positive bacterium Listeria monocytogenes targets the IFN-b gene without detectable MAVS requirement. The data show that MAVS is not a central adapter protein for all cytoplasmic pathogen sensors that stimulate IFN-b synthesis.

Scientific Reports

Intracellular bacteria produce antigens, which serve as potent activators of γδ T cells. Phosphoa... more Intracellular bacteria produce antigens, which serve as potent activators of γδ T cells. Phosphoantigens are presented via a complex of butyrophilins (BTN) to signal infection to human Vγ9+Vδ2+ T cells. Here, we established an in vitro system allowing for studies of Vγ9+Vδ2+ T cell activity in coculture with epithelial cells infected with the intracellular bacterial pathogen Listeria monocytogenes. We report that the Vγ9+Vδ2+ T cells efficiently control L. monocytogenes growth in such cultures. This effector function requires the expression of members of the BTN3A family on epithelial cells. Specifically, we observed a BTN3A1-independent BTN3A3 activity to present antigen to Vγ9+Vδ2+ T cells. Since BTN3A1 is the only BTN3A associated with phosphoantigen presentation, our study suggests that BTN3A3 may present different classes of antigens to mediate Vγ9+Vδ2+ T cell effector function against L. monocytogenes-infected epithelia.

Molecular and Cellular Biology, 1995

Gamma interferon (IFN-gamma), a macrophage-activating cytokine, modulates gene expression through... more Gamma interferon (IFN-gamma), a macrophage-activating cytokine, modulates gene expression through the activity of a transcription factor designated IFN-gamma activation factor (GAF). GAF is formed after phosphorylation on tyrosine and dimerization of the 91-kDa protein STAT1. We have recently reported that differentiation of the promonocytic cell line U937 into monocytes increases the amount of cellular GAF after IFN-gamma treatment and at the same time increases the phosphorylation of STAT1. Here we show that activation of the JAK family kinases, which are instrumental in mediating STAT1 phosphorylation on tyrosine, did not increase upon monocytic U937 differentiation. Consistent with this finding, levels of STAT1 tyrosine phosphorylation were virtually identical in promonocytic and monocytic U937 cells. Analysis of STAT1 phosphoamino acids and mapping of phosphopeptides showed an IFN-gamma-dependent increase in Ser phosphorylation in differentiated cells. Analyses of STAT1 isoform...

Molecular and Cellular Biology, 1996

Tyrosine phosphorylation and activation of the transcription factor Stat5 occur in response to st... more Tyrosine phosphorylation and activation of the transcription factor Stat5 occur in response to stimuli like granulocyte-macrophage colony-stimulating factor, interleukin-3, or erythropoietin that stimulate both proliferation and differentiation of hematopoietic cells. It is unclear whether Stat5 is part of a proliferative response or part of the events leading to cellular differentiation. Here we report that agents promoting differentiation but not proliferation of hematopoietic cells, like phorbol ester or both types of interferons (IFNs), activate Stat5 in promonocytic U937 cells. Both IFN types caused tyrosine phosphorylation and DNA binding of predominantly one Stat5 isoform (Stat5a) despite expression of both Stat5a and Stat5b proteins. Monocytic differentiation of U937 cells led to a strong decrease in IFN-gamma-mediated activation of Stat5 but not of Stat1. Transactivation of Stat5-target genes occurred in response to IFN-gamma, which activates both Stat5 and Stat1, but not i...

The Journal of Immunology, 2002

Type I IFNs (IFN-α/β) modulate innate immune responses. Here we show activation of transcription ... more Type I IFNs (IFN-α/β) modulate innate immune responses. Here we show activation of transcription factor IFN regulatory factor 3, the synthesis of large amounts of IFN-β mRNA, and type I IFN signal transduction in macrophages infected with Listeria monocytogenes. Expression of the bacterial virulence protein listeriolysin O was necessary, but not sufficient, for efficient IFN-β production. Signaling through a pathway involving the type I IFN receptor and Stat1 sensitized macrophages to L. monocytogenes-induced cell death in a manner not requiring inducible NO synthase (nitric oxide synthase 2) or protein kinase R, potential effectors of type I IFN action during microbial infections. The data stress the importance of type I IFN for the course of infections with intracellular bacteria and suggest that factors other than listeriolysin O contribute to macrophage death during Listeria infection.

activation in macrophages. phosphorylation of STAT1 promotes GAF Differentiation-regulated serine

Journal of Experimental Medicine, 2021

Interferons establish innate antiviral immunity. Two recent papers in JEM by Lopez et al. (2021. ... more Interferons establish innate antiviral immunity. Two recent papers in JEM by Lopez et al. (2021. J. Exp. Med.https://doi.org/10.1084/jem.20211211) and Cheemarla et al. (2021. J. Exp. Med.https://doi.org/10.1084/jem.20210583) show that an appropriate supply of antiviral interferon enables epithelial cells of the nasopharyngeal mucosa to inhibit SARS-CoV-2 growth and that interferon-induced mucosal genes serve as biomarkers of infection.

Engagement of macrophages in innate immune responses is directed and enhanced by type I and type ... more Engagement of macrophages in innate immune responses is directed and enhanced by type I and type II interferons. An essential component of IFN activity is the use of JAK-STAT signal transduction for the transcriptional control of interferon-stimulated genes (ISG). Here, we study the immediate early nuclear response to type I IFN and IFN-γ in murine macrophages. Despite their distinct immunological activities, both IFN types triggered highly overlapping epigenomic and transcriptional changes. These changes included a rapid rearrangement of the 3D chromatin organization and an increase of DNA accessibility at ISG loci. ISGF3, the major transcriptional regulator of ISG, controlled homeostatic as well as induced-state DNA accessibility at a subset of ISG. Increases in DNA accessibility correlated with the appearance of activating histone marks at surrounding nucleosomes. Collectively our data emphasize changes in the three-dimensional nuclear space and epigenome as an important facet of...

Listeria monocytogenes (L. monocytogenes) is a food-borne bacterial pathogen. Innate immunity to ... more Listeria monocytogenes (L. monocytogenes) is a food-borne bacterial pathogen. Innate immunity to L. monocytogenes is profoundly affected by type I interferons (IFN-I). Here we investigated host metabolism in L. monocytogenes-infected mice and its potential control by IFN-I. Accordingly, we used animals lacking either the IFN-I receptor (IFNAR) or IRF9, a subunit of ISGF3, the master regulator of IFN-I-induced genes. Transcriptomes and metabolite profiles showed that L. monocytogenes infection induces metabolic rewiring of the liver. This affects various metabolic pathways including fatty acid (FA) metabolism and oxidative phosphorylation and is partially dependent on IFN-I signaling. Livers and macrophages from Ifnar1-/- mice employ increased glutaminolysis in an IRF9-independent manner, possibly to readjust TCA metabolite levels due to reduced FA oxidation. Moreover, FA oxidation inhibition provides protection from L. monocytogenes infection, explaining part of the protection of Ir...

Nature Communications, 2019

Cells maintain the balance between homeostasis and inflammation by adapting and integrating the a... more Cells maintain the balance between homeostasis and inflammation by adapting and integrating the activity of intracellular signaling cascades, including the JAK-STAT pathway. Our understanding of how a tailored switch from homeostasis to a strong receptor-dependent response is coordinated remains limited. Here, we use an integrated transcriptomic and proteomic approach to analyze transcription-factor binding, gene expression and in vivo proximity-dependent labelling of proteins in living cells under homeostatic and interferon (IFN)-induced conditions. We show that interferons (IFN) switch murine macrophages from resting-state to induced gene expression by alternating subunits of transcription factor ISGF3. Whereas preformed STAT2-IRF9 complexes control basal expression of IFN-induced genes (ISG), both type I IFN and IFN-γ cause promoter binding of a complete ISGF3 complex containing STAT1, STAT2 and IRF9. In contrast to the dogmatic view of ISGF3 formation in the cytoplasm, our results suggest a model wherein the assembly of the ISGF3 complex occurs on DNA.

Cells maintain the balance between homeostasis and inflammation by adapting and integrating the a... more Cells maintain the balance between homeostasis and inflammation by adapting and integrating the activity of intracellular signalling cascades, including the JAK-STAT pathway. Our understanding how a tailored switch from homeostasis to a strong receptor-dependent response is coordinated remains limited. We used an integrated transcriptomic and proteomic approach to analyze transcription-factor binding, gene expression and in vivo proximity-dependent labelling of proteins in living cells under homeostatic and interferon (IFN)-induced conditions. We show that interferons (IFN) switch murine macrophages from resting-state to induced gene expression by alternating subunits of transcription factor ISGF3. Whereas preformed STAT2-IRF9 complexes control basal expression of IFN-induced genes (ISG), both type I IFN and, unexpectedly, IFNγ cause promoter binding of a complete ISGF3 complex containing STAT1, STAT2 and IRF9. In contrast to the dogmatic view of ISGF3 formation in the cytoplasm, ou...

Blood, Jan 16, 2018

Inhibition of Janus-kinase 1/2 (JAK1/2) is a mainstay to treat myeloproliferative neoplasms (MPN)... more Inhibition of Janus-kinase 1/2 (JAK1/2) is a mainstay to treat myeloproliferative neoplasms (MPN). Sporadic observations reported the co-incidence of B-cell non-Hodgkin lymphomas during treatment of MPN with JAK1/2 inhibitors. We assessed 626 patients with MPN, including 69 with myelofibrosis receiving JAK1/2 inhibitors for lymphoma development. B-cell lymphomas evolved in 4 (5.8%) of 69 patients receiving JAK1/2 inhibition compared with 2 (0.36%) of 557 with conventional treatment (16-fold increased risk). A similar 15-fold increase was observed in an independent cohort of 929 patients with MPN. Considering primary myelofibrosis only (N = 216), 3 lymphomas were observed in 31 inhibitor-treated patients (9.7%) vs 1 (0.54%) of 185 control patients. Lymphomas were of aggressive B-cell type, extranodal, or leukemic with high MYC expression in the absence of V617F or other MPN-associated mutations. Median time from initiation of inhibitor therapy to lymphoma diagnosis was 25 months. Clo...

PLoS Pathogens, 2012

Signal transducer and activator of transcription 1 (Stat1) is a key player in responses to interf... more Signal transducer and activator of transcription 1 (Stat1) is a key player in responses to interferons (IFN). Mutations of Stat1 cause severe immune deficiencies in humans and mice. Here we investigate the importance of Stat1 signaling for the innate and secondary immune response to the intracellular bacterial pathogen Listeria monocytogenes (Lm). Cell type-restricted ablation of the Stat1 gene in naïve animals revealed unique roles in three cell types: macrophage Stat1 signaling protected against lethal Lm infection, whereas Stat1 ablation in dendritic cells (DC) did not affect survival. T lymphocyte Stat1 reduced survival. Type I IFN (IFN-I) signaling in T lymphocytes reportedly weakens innate resistance to Lm. Surprisingly, the effect of Stat1 signaling was much more pronounced, indicating a contribution of Stat1 to pathways other than the IFN-I pathway. In stark contrast, Stat1 activity in both DC and T cells contributed positively to secondary immune responses against Lm in immunized animals, while macrophage Stat1 was dispensable. Our findings provide the first genetic evidence that Stat1 signaling in different cell types produces antagonistic effects on innate protection against Lm that are obscured in mice with complete Stat1 deficiency. They further demonstrate a drastic change in the cell type-dependent Stat1 requirement for memory responses to Lm infection.

PLoS Pathogens, 2009

Production of type I interferons (IFN-I, mainly IFNa and IFNb) is a hallmark of innate immune res... more Production of type I interferons (IFN-I, mainly IFNa and IFNb) is a hallmark of innate immune responses to all classes of pathogens. When viral infection spreads to lymphoid organs, the majority of systemic IFN-I is produced by a specialized ''interferon-producing cell'' (IPC) that has been shown to belong to the lineage of plasmacytoid dendritic cells (pDC). It is unclear whether production of systemic IFN-I is generally attributable to pDC irrespective of the nature of the infecting pathogen. We have addressed this question by studying infections of mice with the intracellular bacterium Listeria monocytogenes. Protective innate immunity against this pathogen is weakened by IFN-I activity. In mice infected with L. monocytogenes, systemic IFN-I was amplified via IFN-b, the IFN-I receptor (IFNAR), and transcription factor interferon regulatory factor 7 (IRF7), a molecular circuitry usually characteristic of non-pDC producers. Synthesis of serum IFN-I did not require TLR9. In contrast, in vitro-differentiated pDC infected with L. monocytogenes needed TLR9 to transcribe IFN-I mRNA. Consistent with the assumption that pDC are not the producers of systemic IFN-I, conditional ablation of the IFN-I receptor in mice showed that most systemic IFN-I is produced by myeloid cells. Furthermore, results obtained with FACS-purified splenic cell populations from infected mice confirmed the assumption that a cell type with surface antigens characteristic of macrophages and not of pDC is responsible for bulk IFN-I synthesis. The amount of IFN-I produced in the investigated mouse lines was inversely correlated to the resistance to lethal infection. Based on these data, we propose that the engagement of pDC, the mode of IFN-I mobilization, as well as the shaping of the antimicrobial innate immune response by IFN-I differ between intracellular pathogens.

Nature Immunology, 2003

Toll-like receptor-4 activation by lipopolysaccharide (LPS) induces the expression of interferon-... more Toll-like receptor-4 activation by lipopolysaccharide (LPS) induces the expression of interferon-β (IFN-β) in a MyD88-independent manner. Here we report that mice devoid of the JAK protein tyrosine kinase family member,Tyk2, were resistant to shock induced by high doses of LPS. Basal and LPS-induced expression of IFN-β and IFN-α4 mRNA in Tyk2-null macrophages were diminished. However, Tyk2-null mice showed normal systemic production of nitric oxide and proinflammatory cytokines and the in vivo response to tumor necrosis factor (TNF) was unperturbed. IFN-β-null but not STAT1-null mice were also resistant to high dose LPS treatment. Together, these data suggest that Tyk2 and IFN-β are essential effectors in LPS induced lethality.

The Journal of Immunology, 2009

Phosphorylation of transcription factor STAT-1 on Y701 regulates subcellular localization whereas... more Phosphorylation of transcription factor STAT-1 on Y701 regulates subcellular localization whereas phosphorylation of the transactivating domain at S727 enhances transcriptional activity. In this study, we investigate the impact of STAT-1 and the importance of transactivating domain phosphorylation on the induction of peptide-specific CTL in presence of the TLR9-dependent immune adjuvant IC31. STAT-1 deficiency completely abolished CTL induction upon immunization, which was strongly reduced in animals carrying the mutation of the S727 phospho-acceptor site. A comparable reduction of CTL was found in mice lacking the type I IFN (IFN-I) receptor, whereas IFN-␥-deficient mice behaved like wild-type controls. This finding suggests that S727phosphorylated STAT-1 supports IFN-I-dependent induction of CTL. In adoptive transfer experiments, IFN-I-and S727-phosphorylated STAT-1 were critical for the activation and function of dendritic cells. Mice with a T cell-specific IFN-I receptor ablation did not show impaired CTL responses. Unlike the situation observed for CTL development S727-phosphorylated STAT-1 restrained proliferation of naive CD8 ؉ T cells both in vitro and following transfer into Rag-deficient mice. In summary, our data reveal a dual role of S727-phosphorylated STAT-1 for dendritic cell maturation as a prerequisite for the induction of CTL activity and for T cell autonomous control of activation-induced or homeostatic proliferation.

Journal of Clinical Investigation, 2002

Innate immune responses derive from the ability of cells to rapidly combat invading microorganism... more Innate immune responses derive from the ability of cells to rapidly combat invading microorganisms without the requirement for an antigen-specific adaptation. These mechanisms have evolved to recognize common microbe-associated molecular patterns and to interfere with conserved replication and survival strategies that support the propagation of microbial invaders. Here, we consider the contributions of one cytokine family, the IFNs, to these innate defense mechanisms. IFNs were first recognized for their ability to impede viral replication, a function that is indeed critical for host survival in response to viral infection. In addition, IFN signaling is now known to play key roles in defending the host from bacteria and other pathogens and to help integrate early, innate responses with later events mediated by the adaptive immune system. The two recognized types of IFN exhibit distinct immunological properties (1). In humans and mice, type I IFNs include a number of IFN-α subtypes and a single species of IFN-β. (The immunological impact of another type I IFN, IFN-ω, is poorly understood and will not be considered here). While type I IFNs can be produced by all cells under appropriate conditions, a subpopulation of immature dendritic cells (DCs) that will be described in more detail below stands out for the extent of its contribution to overall IFN production during infections. IFN-γ is a type II IFN and serves not only to induce antiviral function, but also to activate macrophages, which strengthens innate responses to unicellular microorganisms (2). Unlike the type I IFNs, IFN-γ is produced by a limited number of cell types: activated NK cells, activated Th1 cells, and, in the presence of IL-12 and IL-18, activated DCs and macrophages. Expression of IFN-γ by Th1 cells provides an important link by which the adaptive immune response reinforces macrophage-based innate immunity. JAK-STAT signaling in IFN responses A common property of both IFN types is to induce immediate transcriptional responses through a JAK-STAT signal transduction pathway (3). All type I IFNs bind to a class II cytokine receptor composed of IFN-α receptor 1 (IFNAR1) and IFNAR2 chains, which are associated with the Janus kinases (JAKs) TYK2 and JAK1, respectively. Ligand-bound, tyrosine-phosphorylated receptor complexes bind the SH2 domains of signal transducers and activators of transcription (STATs) 1 and 2, causing phosphorylation of the proteins on tyrosines 701 and 692, respectively. Interaction of STATs through reciprocal SH2 domain-phosphotyrosine binding results in formation of two distinct transcription factor complexes. ISGF3, a heteromeric complex consisting of STAT1 and STAT2 in association with a third protein, p48 or IRF9, associates specifically with and transactivates genes with interferon-stimulated response elements (ISRE) in their promoter or enhancer regions. A simpler complex, consisting solely of the STAT1 homodimer, is also active as a transcription factor and binds to different DNA sequences, termed IFN-γ-activated site (GAS) elements (Figure 1). The receptor for IFN-γ is structurally related to that for type I IFN. It consists of IFN-γ receptor 1 (IFNGR1) and IFNGR2 chains in association with JAK1 and JAK2 kinases. Once tyrosine-phosphorylated in the presence of ligand, it binds STAT1 and causes phosphorylation of Y701. STAT1 homodimers are formed, move to the nucleus, and regulate transcription of promoters containing GAS sequences (Figure 1; ref. 4). Recent evidence indicates that nuclear responses can be stimulated by IFN-γ in the absence of STAT1 (5), but the transcription factors mediating the STAT1-independent response remain to be identified. In addition, some genes are induced by IFN-γ only in the absence of STAT1, suggesting that this protein can also mediate transcriptional repression. Innate immunity to viruses Cells in culture respond to viruses by deploying a complex network of signaling molecules that initiate and then amplify the production of type I IFNs. At an early

Immunity, 2010

Transcriptional regulation of the Nos2 gene encoding inducible nitric oxide synthase (iNOS) requi... more Transcriptional regulation of the Nos2 gene encoding inducible nitric oxide synthase (iNOS) requires type I interferon (IFN-I) signaling and additional signals emanating from pattern recognition receptors. Here we showed sequential and cooperative contributions of the transcription factors ISGF3 (a complex containing STAT1, STAT2, and IRF9 subunits) and NF-kB to the transcriptional induction of the Nos2 gene in macrophages infected with the intracellular bacterial pathogen Listeria monocytogenes. NF-kB preceded ISGF3 at the Nos2 promoter and generated a transcriptional memory effect by depositing basal transcription factor TFIIH with the associated CDK7 kinase for serine 5 phosphorylation of the RNA polymerase II (pol II) carboxyterminal domain (CTD). Subsequent to TFIIH deposition by NF-kB, ISGF3 attracted the pol II enzyme and phosphorylation at CTD S5 occurred. Thus, STATs and NF-kB cooperate through pol II promoter recruitment and the phosphorylation of its CTD, respectively, as a prerequisite for productive elongation of iNOS mRNA.

FEBS Letters, 2006

The mitochondria-associated adapter protein MAVS (also called IPS-1, VISA or CARDIF, designated M... more The mitochondria-associated adapter protein MAVS (also called IPS-1, VISA or CARDIF, designated MAVS for reasons of simplicity in our manuscript) relays signals from cytoplasmic sensors of viral RNA to the IRF3 kinase complex and the interferon-b (IFN-b) gene. Using siRNA-mediated knockdown in macrophages we show that IFN-b synthesis in response to transfected, intracellular double-stranded RNA (dsRNA), a pathogen-associated molecular pattern of viruses, is decreased in absence of MAVS. By contrast, the Gram-positive bacterium Listeria monocytogenes targets the IFN-b gene without detectable MAVS requirement. The data show that MAVS is not a central adapter protein for all cytoplasmic pathogen sensors that stimulate IFN-b synthesis.