Publications by authors named "Caetano Reis e Sousa"

118 Publications

Dendritic Cells Revisited.

Annu Rev Immunol 2021 Apr 22;39:131-166. Epub 2021 Jan 22.

Immunobiology Laboratory, The Francis Crick Institute, London NW1 1AT, United Kingdom; email:

Dendritic cells (DCs) possess the ability to integrate information about their environment and communicate it to other leukocytes, shaping adaptive and innate immunity. Over the years, a variety of cell types have been called DCs on the basis of phenotypic and functional attributes. Here, we refocus attention on conventional DCs (cDCs), a discrete cell lineage by ontogenetic and gene expression criteria that best corresponds to the cells originally described in the 1970s. We summarize current knowledge of mouse and human cDC subsets and describe their hematopoietic development and their phenotypic and functional attributes. We hope that our effort to review the basic features of cDC biology and distinguish cDCs from related cell types brings to the fore the remarkable properties of this cell type while shedding some light on the seemingly inordinate complexity of the DC field.
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http://dx.doi.org/10.1146/annurev-immunol-061020-053707DOI Listing
April 2021

The receptor DNGR-1 signals for phagosomal rupture to promote cross-presentation of dead-cell-associated antigens.

Nat Immunol 2021 02 21;22(2):140-153. Epub 2020 Dec 21.

Immunobiology Laboratory, The Francis Crick Institute, London, UK.

Type 1 conventional dendritic (cDC1) cells are necessary for cross-presentation of many viral and tumor antigens to CD8 T cells. cDC1 cells can be identified in mice and humans by high expression of DNGR-1 (also known as CLEC9A), a receptor that binds dead-cell debris and facilitates XP of corpse-associated antigens. Here, we show that DNGR-1 is a dedicated XP receptor that signals upon ligand engagement to promote phagosomal rupture. This allows escape of phagosomal contents into the cytosol, where they access the endogenous major histocompatibility complex class I antigen processing pathway. The activity of DNGR-1 maps to its signaling domain, which activates SYK and NADPH oxidase to cause phagosomal damage even when spliced into a heterologous receptor and expressed in heterologous cells. Our data reveal the existence of innate immune receptors that couple ligand binding to endocytic vesicle damage to permit MHC class I antigen presentation of exogenous antigens and to regulate adaptive immunity.
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http://dx.doi.org/10.1038/s41590-020-00824-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7116638PMC
February 2021

Antagonistic Inflammatory Phenotypes Dictate Tumor Fate and Response to Immune Checkpoint Blockade.

Immunity 2020 12 20;53(6):1215-1229.e8. Epub 2020 Nov 20.

Cancer Research UK Manchester Institute, The University of Manchester, Alderley Park, UK. Electronic address:

Inflammation can support or restrain cancer progression and the response to therapy. Here, we searched for primary regulators of cancer-inhibitory inflammation through deep profiling of inflammatory tumor microenvironments (TMEs) linked to immune-dependent control in mice. We found that early intratumoral accumulation of interferon gamma (IFN-γ)-producing natural killer (NK) cells induced a profound remodeling of the TME and unleashed cytotoxic T cell (CTL)-mediated tumor eradication. Mechanistically, tumor-derived prostaglandin E2 (PGE2) acted selectively on EP2 and EP4 receptors on NK cells, hampered the TME switch, and enabled immune evasion. Analysis of patient datasets across human cancers revealed distinct inflammatory TME phenotypes resembling those associated with cancer immune control versus escape in mice. This allowed us to generate a gene-expression signature that integrated opposing inflammatory factors and predicted patient survival and response to immune checkpoint blockade. Our findings identify features of the tumor inflammatory milieu associated with immune control of cancer and establish a strategy to predict immunotherapy outcomes.
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http://dx.doi.org/10.1016/j.immuni.2020.10.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7772804PMC
December 2020

Cross-presentation of dead-cell-associated antigens by DNGR-1 dendritic cells contributes to chronic allograft rejection in mice.

Eur J Immunol 2020 12 26;50(12):2041-2054. Epub 2020 Jul 26.

Department of Surgery, University Medical Center Regensburg, Regensburg, Germany.

The purpose of this study was to elucidate whether DC NK lectin group receptor-1 (DNGR-1)-dependent cross-presentation of dead-cell-associated antigens occurs after transplantation and contributes to CD8 T cell responses, chronic allograft rejection (CAR), and fibrosis. BALB/c or C57BL/6 hearts were heterotopically transplanted into WT, Clec9a , or Batf3 recipient C57BL/6 mice. Allografts were analyzed for cell infiltration, CD8 T cell activation, fibrogenesis, and CAR using immunohistochemistry, Western blot, qRT -PCR, and flow cytometry. Allografts displayed infiltration by recipient DNGR-1 DCs, signs of CAR, and fibrosis. Allografts in Clec9a recipients showed reduced CAR (p < 0.0001), fibrosis (P = 0.0137), CD8 cell infiltration (P < 0.0001), and effector cytokine levels compared to WT recipients. Batf3-deficiency greatly reduced DNGR-1 DC-infiltration, CAR (P < 0.0001), and fibrosis (P = 0.0382). CD8 cells infiltrating allografts of cytochrome C treated recipients, showed reduced production of CD8 effector cytokines (P < 0.05). Further, alloreactive CD8 T cell response in indirect pathway IFN-γ ELISPOT was reduced in Clec9a recipient mice (P = 0.0283). Blockade of DNGR-1 by antibody, similar to genetic elimination of the receptor, reduced CAR (P = 0.0003), fibrosis (P = 0.0273), infiltration of CD8 cells (p = 0.0006), and effector cytokine levels. DNGR-1-dependent alloantigen cross-presentation by DNGR-1 DCs induces alloreactive CD8 cells that induce CAR and fibrosis. Antibody against DNGR-1 can block this process and prevent CAR and fibrosis.
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http://dx.doi.org/10.1002/eji.201948501DOI Listing
December 2020

Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition).

Eur J Immunol 2019 Oct;49(10):1457-1973

Flow Cytometry Laboratory, Institute of Molecular Toxicology and Pharmacology, Helmholtz Zentrum München, German Research Center for Environmental Health, München, Germany.

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.
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http://dx.doi.org/10.1002/eji.201970107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7350392PMC
October 2019

Cytoskeletal Exposure in the Regulation of Immunity and Initiation of Tissue Repair.

Bioessays 2019 07 3;41(7):e1900021. Epub 2019 Jun 3.

Immunobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.

This article reviews and discusses emerging evidence suggesting an evolutionarily-conserved connection between injury-associated exposure of cytoskeletal proteins and the induction of tolerance to infection, repair of tissue damage and restoration of homeostasis. While differences exist between vertebrates and invertebrates with respect to the receptor(s), cell types, and effector mechanisms involved, the response to exposed cytoskeletal proteins appears to be protective and to rely on a conserved signaling cassette involving Src family kinases, the nonreceptor tyrosine kinase Syk, and tyrosine phosphatases. A case is made for research programs that integrate different model organisms in order to increase the understanding of this putative response to tissue damage.
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http://dx.doi.org/10.1002/bies.201900021DOI Listing
July 2019

Slicing and dicing viruses: antiviral RNA interference in mammals.

EMBO J 2019 04 14;38(8). Epub 2019 Mar 14.

Immunobiology Laboratory, The Francis Crick Institute, London, UK

To protect against the harmful consequences of viral infections, organisms are equipped with sophisticated antiviral mechanisms, including cell-intrinsic means to restrict viral replication and propagation. Plant and invertebrate cells utilise mostly RNA interference (RNAi), an RNA-based mechanism, for cell-intrinsic immunity to viruses while vertebrates rely on the protein-based interferon (IFN)-driven innate immune system for the same purpose. The RNAi machinery is conserved in vertebrate cells, yet whether antiviral RNAi is still active in mammals and functionally relevant to mammalian antiviral defence is intensely debated. Here, we discuss cellular and viral factors that impact on antiviral RNAi and the contexts in which this system might be at play in mammalian resistance to viral infection.
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http://dx.doi.org/10.15252/embj.2018100941DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6463209PMC
April 2019

Tissue clonality of dendritic cell subsets and emergency DCpoiesis revealed by multicolor fate mapping of DC progenitors.

Sci Immunol 2019 03;4(33)

Immunobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.

Conventional dendritic cells (cDCs) are found in all tissues and play a key role in immune surveillance. They comprise two major subsets, cDC1 and cDC2, both derived from circulating precursors of cDCs (pre-cDCs), which exited the bone marrow. We show that, in the steady-state mouse, pre-cDCs entering tissues proliferate to give rise to differentiated cDCs, which themselves have residual proliferative capacity. We use multicolor fate mapping of cDC progenitors to show that this results in clones of sister cDCs, most of which comprise a single cDC1 or cDC2 subtype, suggestive of pre-cDC commitment. Upon infection, a surge in the influx of pre-cDCs into the affected tissue dilutes clones and increases cDC numbers. Our results indicate that tissue cDCs can be organized in a patchwork of closely positioned sister cells of the same subset whose coexistence is perturbed by local infection, when the bone marrow provides additional pre-cDCs to meet increased tissue demand.
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http://dx.doi.org/10.1126/sciimmunol.aaw1941DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6420147PMC
March 2019

Direct reprogramming of fibroblasts into antigen-presenting dendritic cells.

Sci Immunol 2018 12;3(30)

Molecular Medicine and Gene Therapy, Lund Stem Cell Center, Lund University, BMC A12, 221 84, Lund, Sweden.

Ectopic expression of transcription factors has been used to reprogram differentiated somatic cells toward pluripotency or to directly reprogram them to other somatic cell lineages. This concept has been explored in the context of regenerative medicine. Here, we set out to generate dendritic cells (DCs) capable of presenting antigens from mouse and human fibroblasts. By screening combinations of 18 transcription factors that are expressed in DCs, we have identified PU.1, IRF8, and BATF3 transcription factors as being sufficient to reprogram both mouse and human fibroblasts to induced DCs (iDCs). iDCs acquire a conventional DC type 1-like transcriptional program, with features of interferon-induced maturation. iDCs secrete inflammatory cytokines and have the ability to engulf, process, and present antigens to T cells. Furthermore, we demonstrate that murine iDCs generated here were able to cross-present antigens to CD8 T cells. Our reprogramming system should facilitate better understanding of DC specification programs and serve as a platform for the development of patient-specific DCs for immunotherapy.
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http://dx.doi.org/10.1126/sciimmunol.aau4292DOI Listing
December 2018

The Role of Type 1 Conventional Dendritic Cells in Cancer Immunity.

Trends Cancer 2018 11 29;4(11):784-792. Epub 2018 Sep 29.

Immunobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK. Electronic address:

Dendritic cells (DCs) are key orchestrators of immune responses. A specific DC subset, conventional type 1 DCs (cDC1s), has been recently associated with human cancer patient survival and, in preclinical models, is critical for the spontaneous rejection of immunogenic cancers and for the success of T cell-based immunotherapies. The unique role of cDC1 reflects the ability to initiate de novo T cell responses after migrating to tumor-draining lymph nodes, as well as to attract T cells, secrete cytokines, and present tumor antigens within the tumor microenvironment, enhancing local cytotoxic T cell function. Strategies aimed at increasing cDC1 abundance in tumors and enhancing their functionality provide attractive new avenues to boost anti-tumor immunity and overcome resistance to cancer immunotherapies.
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http://dx.doi.org/10.1016/j.trecan.2018.09.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6207145PMC
November 2018

α-actinin accounts for the bioactivity of actin preparations in inducing STAT target genes in .

Elife 2018 09 27;7. Epub 2018 Sep 27.

Immunobiology Laboratory, The Francis Crick Institute, London, United Kingdom.

Damage-associated molecular patterns (DAMPs) are molecules exposed or released by dead cells that trigger or modulate immunity and tissue repair. In vertebrates, the cytoskeletal component F-actin is a DAMP specifically recognised by DNGR-1, an innate immune receptor. Previously we suggested that actin is also a DAMP in by inducing STAT-dependent genes (Srinivasan et al., 2016). Here, we revise that conclusion and report that α-actinin is far more potent than actin at inducing the same STAT response and can be found in trace amounts in actin preparations. Recombinant expression of actin or α-actinin in bacteria demonstrated that only α-actinin could drive the expression of STAT target genes in . The response to injected α-actinin required the same signalling cascade that we had identified in our previous work using actin preparations. Taken together, these data indicate that α-actinin rather than actin drives STAT activation when injected into .
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http://dx.doi.org/10.7554/eLife.38636DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6170186PMC
September 2018

Myosin II Synergizes with F-Actin to Promote DNGR-1-Dependent Cross-Presentation of Dead Cell-Associated Antigens.

Cell Rep 2018 07;24(2):419-428

Immunobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK. Electronic address:

Conventional type 1 DCs (cDC1s) excel at cross-presentation of dead cell-associated antigens partly because they express DNGR-1, a receptor that recognizes exposed actin filaments on dead cells. In vitro polymerized F-actin can be used as a synthetic ligand for DNGR-1. However, cellular F-actin is decorated with actin-binding proteins, which could affect DNGR-1 recognition. Here, we demonstrate that myosin II, an F-actin-associated motor protein, greatly potentiates the binding of DNGR-1 to F-actin. Latex beads coated with F-actin and myosin II are taken up by DNGR-1 cDC1s, and antigen associated with those beads is efficiently cross-presented to CD8 T cells. Myosin II-deficient necrotic cells are impaired in their ability to stimulate DNGR-1 or to serve as substrates for cDC1 cross-presentation to CD8 T cells. These results provide insights into the nature of the DNGR-1 ligand and have implications for understanding immune responses to cell-associated antigens and for vaccine design.
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http://dx.doi.org/10.1016/j.celrep.2018.06.038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6057488PMC
July 2018

Molecular mechanism of influenza A NS1-mediated TRIM25 recognition and inhibition.

Nat Commun 2018 05 8;9(1):1820. Epub 2018 May 8.

Molecular Structure of Cell Signalling Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.

RIG-I is a viral RNA sensor that induces the production of type I interferon (IFN) in response to infection with a variety of viruses. Modification of RIG-I with K63-linked poly-ubiquitin chains, synthesised by TRIM25, is crucial for activation of the RIG-I/MAVS signalling pathway. TRIM25 activity is targeted by influenza A virus non-structural protein 1 (NS1) to suppress IFN production and prevent an efficient host immune response. Here we present structures of the human TRIM25 coiled-coil-PRYSPRY module and of complexes between the TRIM25 coiled-coil domain and NS1. These structures show that binding of NS1 interferes with the correct positioning of the PRYSPRY domain of TRIM25 required for substrate ubiquitination and provide a mechanistic explanation for how NS1 suppresses RIG-I ubiquitination and hence downstream signalling. In contrast, the formation of unanchored K63-linked poly-ubiquitin chains is unchanged by NS1 binding, indicating that RING dimerisation of TRIM25 is not affected by NS1.
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http://dx.doi.org/10.1038/s41467-018-04214-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5940772PMC
May 2018

Mediated Ablation of Conventional Dendritic Cells Suggests a Lymphoid Path to Generating Dendritic Cells .

Front Immunol 2018 16;9:699. Epub 2018 Apr 16.

Walter-Brendel-Centre for Experimental Medicine, University Hospital, LMU Munich, Planegg Martinsried, Germany.

Conventional dendritic cells (cDCs) are versatile activators of immune responses that develop as part of the myeloid lineage downstream of hematopoietic stem cells. We have recently shown that in mice precursors of cDCs, but not of other leukocytes, are marked by expression of DNGR-1/CLEC9A. To genetically deplete DNGR-1-expressing cDC precursors and their progeny, we crossed mice to Rosa-lox-STOP-lox-diphtheria toxin (DTA) mice. These mice develop signs of age-dependent myeloproliferative disease, as has been observed in other DC-deficient mouse models. However, despite efficient depletion of cDC progenitors in these mice, cells with phenotypic characteristics of cDCs populate the spleen. These cells are functionally and transcriptionally similar to cDCs in wild type control mice but show somatic rearrangements of Ig-heavy chain genes, characteristic of lymphoid origin cells. Our studies reveal a previously unappreciated developmental heterogeneity of cDCs and suggest that the lymphoid lineage can generate cells with features of cDCs when myeloid cDC progenitors are impaired.
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http://dx.doi.org/10.3389/fimmu.2018.00699DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5911463PMC
June 2019

NK Cells Stimulate Recruitment of cDC1 into the Tumor Microenvironment Promoting Cancer Immune Control.

Cell 2018 02 8;172(5):1022-1037.e14. Epub 2018 Feb 8.

Immunobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK. Electronic address:

Conventional type 1 dendritic cells (cDC1) are critical for antitumor immunity, and their abundance within tumors is associated with immune-mediated rejection and the success of immunotherapy. Here, we show that cDC1 accumulation in mouse tumors often depends on natural killer (NK) cells that produce the cDC1 chemoattractants CCL5 and XCL1. Similarly, in human cancers, intratumoral CCL5, XCL1, and XCL2 transcripts closely correlate with gene signatures of both NK cells and cDC1 and are associated with increased overall patient survival. Notably, tumor production of prostaglandin E2 (PGE) leads to evasion of the NK cell-cDC1 axis in part by impairing NK cell viability and chemokine production, as well as by causing downregulation of chemokine receptor expression in cDC1. Our findings reveal a cellular and molecular checkpoint for intratumoral cDC1 recruitment that is targeted by tumor-derived PGE for immune evasion and that could be exploited for cancer therapy.
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http://dx.doi.org/10.1016/j.cell.2018.01.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5847168PMC
February 2018

The RIG-I-like receptor LGP2 inhibits Dicer-dependent processing of long double-stranded RNA and blocks RNA interference in mammalian cells.

EMBO J 2018 02 19;37(4). Epub 2018 Jan 19.

Immunobiology Laboratory, The Francis Crick Institute, London, UK

In vertebrates, the presence of viral RNA in the cytosol is sensed by members of the RIG-I-like receptor (RLR) family, which signal to induce production of type I interferons (IFN). These key antiviral cytokines act in a paracrine and autocrine manner to induce hundreds of interferon-stimulated genes (ISGs), whose protein products restrict viral entry, replication and budding. ISGs include the RLRs themselves: RIG-I, MDA5 and, the least-studied family member, LGP2. In contrast, the IFN system is absent in plants and invertebrates, which defend themselves from viral intruders using RNA interference (RNAi). In RNAi, the endoribonuclease Dicer cleaves virus-derived double-stranded RNA (dsRNA) into small interfering RNAs (siRNAs) that target complementary viral RNA for cleavage. Interestingly, the RNAi machinery is conserved in mammals, and we have recently demonstrated that it is able to participate in mammalian antiviral defence in conditions in which the IFN system is suppressed. In contrast, when the IFN system is active, one or more ISGs act to mask or suppress antiviral RNAi. Here, we demonstrate that LGP2 constitutes one of the ISGs that can inhibit antiviral RNAi in mammals. We show that LGP2 associates with Dicer and inhibits cleavage of dsRNA into siRNAs both and in cells. Further, we show that in differentiated cells lacking components of the IFN response, ectopic expression of LGP2 interferes with RNAi-dependent suppression of gene expression. Conversely, genetic loss of LGP2 uncovers dsRNA-mediated RNAi albeit less strongly than complete loss of the IFN system. Thus, the inefficiency of RNAi as a mechanism of antiviral defence in mammalian somatic cells can be in part attributed to Dicer inhibition by LGP2 induced by type I IFNs. LGP2-mediated antagonism of dsRNA-mediated RNAi may help ensure that viral dsRNA substrates are preserved in order to serve as targets of antiviral ISG proteins.
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http://dx.doi.org/10.15252/embj.201797479DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5813259PMC
February 2018

Dendritic Cell Lineage Potential in Human Early Hematopoietic Progenitors.

Cell Rep 2017 07;20(3):529-537

Immunobiology Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK. Electronic address:

Conventional dendritic cells (cDCs) are thought to descend from a DC precursor downstream of the common myeloid progenitor (CMP). However, a mouse lymphoid-primed multipotent progenitor has been shown to generate cDCs following a DC-specific developmental pathway independent of monocyte and granulocyte poiesis. Similarly, here we show that, in humans, a large fraction of multipotent lymphoid early progenitors (MLPs) gives rise to cDCs, in particular the subset known as cDC1, identified by co-expression of DNGR-1 (CLEC9A) and CD141 (BDCA-3). Single-cell analysis indicates that over one-third of MLPs have the potential to efficiently generate cDCs. cDC1s generated from CMPs or MLPs do not exhibit differences in transcriptome or phenotype. These results demonstrate an early imprinting of the cDC lineage in human hematopoiesis and highlight the plasticity of developmental pathways giving rise to human DCs.
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http://dx.doi.org/10.1016/j.celrep.2017.06.075DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5529209PMC
July 2017

Sensing infection and tissue damage.

EMBO Mol Med 2017 03;9(3):285-288

Immunobiology Laboratory, The Francis Crick Institute, London, UK.

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http://dx.doi.org/10.15252/emmm.201607227DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5331196PMC
March 2017

Actin is an evolutionarily-conserved damage-associated molecular pattern that signals tissue injury in .

Elife 2016 11 22;5. Epub 2016 Nov 22.

Immunobiology Laboratory, The Francis Crick Institute, London, United Kingdom.

Damage-associated molecular patterns (DAMPs) are molecules released by dead cells that trigger sterile inflammation and, in vertebrates, adaptive immunity. Actin is a DAMP detected in mammals by the receptor, DNGR-1, expressed by dendritic cells (DCs). DNGR-1 is phosphorylated by Src-family kinases and recruits the tyrosine kinase Syk to promote DC cross-presentation of dead cell-associated antigens. Here we report that actin is also a DAMP in invertebrates that lack DCs and adaptive immunity. Administration of actin to triggers a response characterised by selective induction of STAT target genes in the fat body through the cytokine Upd3 and its JAK/STAT-coupled receptor, Domeless. Notably, this response requires signalling via Shark, the orthologue of Syk, and Src42A, a Src-family kinase, and is dependent on Nox activity. Thus, extracellular actin detection via a Src-family kinase-dependent cascade is an ancient means of detecting cell injury that precedes the evolution of adaptive immunity.
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http://dx.doi.org/10.7554/eLife.19662DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5138034PMC
November 2016

Inactivation of the type I interferon pathway reveals long double-stranded RNA-mediated RNA interference in mammalian cells.

EMBO J 2016 12 4;35(23):2505-2518. Epub 2016 Nov 4.

Immunobiology Laboratory, The Francis Crick Institute, London, UK

RNA interference (RNAi) elicited by long double-stranded (ds) or base-paired viral RNA constitutes the major mechanism of antiviral defence in plants and invertebrates. In contrast, it is controversial whether it acts in chordates. Rather, in vertebrates, viral RNAs induce a distinct defence system known as the interferon (IFN) response. Here, we tested the possibility that the IFN response masks or inhibits antiviral RNAi in mammalian cells. Consistent with that notion, we find that sequence-specific gene silencing can be triggered by long dsRNAs in differentiated mouse cells rendered deficient in components of the IFN pathway. This unveiled response is dependent on the canonical RNAi machinery and is lost upon treatment of IFN-responsive cells with type I IFN Notably, transfection with long dsRNA specifically vaccinates IFN-deficient cells against infection with viruses bearing a homologous sequence. Thus, our data reveal that RNAi constitutes an ancient antiviral strategy conserved from plants to mammals that precedes but has not been superseded by vertebrate evolution of the IFN system.
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http://dx.doi.org/10.15252/embj.201695086DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5167344PMC
December 2016

A pH- and ionic strength-dependent conformational change in the neck region regulates DNGR-1 function in dendritic cells.

EMBO J 2016 11 17;35(22):2484-2497. Epub 2016 Oct 17.

Immunobiology Laboratory, The Francis Crick Institute, London, UK

DNGR-1 is receptor expressed by certain dendritic cell (DC) subsets and by DC precursors in mouse. It possesses a C-type lectin-like domain (CTLD) followed by a poorly characterized neck region coupled to a transmembrane region and short intracellular tail. The CTLD of DNGR-1 binds F-actin exposed by dead cell corpses and causes the receptor to signal and potentiate cross-presentation of dead cell-associated antigens by DCs. Here, we describe a conformational change that occurs in the neck region of DNGR-1 in a pH- and ionic strength-dependent manner and that controls cross-presentation of dead cell-associated antigens. We identify residues in the neck region that, when mutated, lock DNGR-1 in one of the two conformational states to potentiate cross-presentation. In contrast, we show that chimeric proteins in which the neck region of DNGR-1 is replaced by that of unrelated C-type lectin receptors fail to promote cross-presentation. Our results suggest that the neck region of DNGR-1 is an integral receptor component that senses receptor progression through the endocytic pathway and has evolved to maximize extraction of antigens from cell corpses, coupling DNGR-1 function to its cellular localization.
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http://dx.doi.org/10.15252/embj.201694695DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5109244PMC
November 2016

Reducing prostaglandin E2 production to raise cancer immunogenicity.

Oncoimmunology 2016 May 4;5(5):e1123370. Epub 2016 Jan 4.

Immunobiology Laboratory, The Francis Crick Institute, Lincoln's Inn Fields Laboratory , 44 Lincoln's Inn Fields , London, UK.

Cyclooxygenases (COX), commonly upregulated in numerous cancers, generate prostaglandin E2 (PGE2), which has been implicated in key aspects of malignant growth including proliferation, invasion and angiogenesis. Recently, we showed that production of PGE2 by cancer cells dominantly enables progressive tumor growth via immune escape and that cyclooxygenase inhibitors synergize with immunotherapy to enhance tumor eradication.
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http://dx.doi.org/10.1080/2162402X.2015.1123370DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4910741PMC
May 2016

Dendritic cells in remodeling of lymph nodes during immune responses.

Immunol Rev 2016 May;271(1):221-9

Immunobiology Laboratory, The Francis Crick Institute, Lincoln's Inn Fields Laboratory, London, UK.

A critical hallmark of adaptive immune responses is the rapid and extensive expansion of lymph nodes. During this process, the complex internal structure of the organs is maintained revealing the existence of mechanisms able to balance lymph node integrity with structural flexibility. This article reviews the extensive architectural remodeling that occurs within lymph nodes during adaptive immune responses and how it is regulated by dendritic cells (DCs). In particular we focus on previously unappreciated functions of DCs in coordinating remodeling of lymph node vasculature, expansion of the fibroblastic reticular network and maintenance of lymphoid stromal phenotypes. Our increased understanding of these processes indicates that DCs need to be viewed not only as key antigen-presenting cells for lymphocytes but also as broad-acting immune sentinels that convey signals to lymphoid organ stroma and thereby facilitate immune response initiation at multiple levels.
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http://dx.doi.org/10.1111/imr.12414DOI Listing
May 2016

Alive but Confused: Heterogeneity of CD11c(+) MHC Class II(+) Cells in GM-CSF Mouse Bone Marrow Cultures.

Immunity 2016 01;44(1):3-4

Immunobiology Laboratory, The Francis Crick Institute, Lincoln's Inn Fields Laboratory, 44 Lincoln's Inn Fields, London WC2A 3LY, UK. Electronic address:

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http://dx.doi.org/10.1016/j.immuni.2015.12.014DOI Listing
January 2016

Drosha cuts the tethers of myelopoiesis.

Nat Immunol 2015 Nov;16(11):1110-2

Immunobiology Laboratory, The Francis Crick Institute, Lincoln's Inn Fields Laboratory, London, UK.

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http://dx.doi.org/10.1038/ni.3297DOI Listing
November 2015

Oncogenic Transformation of Dendritic Cells and Their Precursors Leads to Rapid Cancer Development in Mice.

J Immunol 2015 Nov 12;195(10):5066-76. Epub 2015 Oct 12.

Immunobiology Laboratory, The Francis Crick Institute, Lincoln's Inn Fields Laboratory, London WC2A 3LY, United Kingdom

Dendritic cells (DCs) are powerful APCs that can induce Ag-specific adaptive immune responses and are increasingly recognized as important players in innate immunity to both infection and malignancy. Interestingly, although there are multiple described hematological malignancies, DC cancers are rarely observed in humans. Whether this is linked to the immunogenic potential of DCs, which might render them uniquely susceptible to immune control upon neoplastic transformation, has not been fully investigated. To address the issue, we generated a genetically engineered mouse model in which expression of Cre recombinase driven by the C-type lectin domain family 9, member a (Clec9a) locus causes expression of the Kirsten rat sarcoma viral oncogene homolog (Kras)(G12D) oncogenic driver and deletion of the tumor suppressor p53 within developing and differentiated DCs. We show that these Clec9a(Kras-G12D) mice rapidly succumb from disease and display massive accumulation of transformed DCs in multiple organs. In bone marrow chimeras, the development of DC cancer could be induced by a small number of transformed cells and was not prevented by the presence of untransformed DCs. Notably, activation of transformed DCs did not happen spontaneously but could be induced upon stimulation. Although Clec9a(Kras-G12D) mice showed altered thymic T cell development, peripheral T cells were largely unaffected during DC cancer development. Interestingly, transformed DCs were rejected upon adoptive transfer into wild-type but not lymphocyte-deficient mice, indicating that immunological control of DC cancer is in principle possible but does not occur during spontaneous generation in Clec9a(Kras-G12D) mice. Our findings suggest that neoplastic transformation of DCs does not by default induce anti-cancer immunity and can develop unhindered by immunological barriers.
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http://dx.doi.org/10.4049/jimmunol.1500889DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4635568PMC
November 2015