Publications by authors named "Boris Reizis"

99 Publications

Human plasmacytoid dendritic cells mount a distinct antiviral response to virus-infected cells.

Sci Immunol 2021 Apr;6(58)

Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA.

Plasmacytoid dendritic cells (pDCs) can rapidly produce interferons and other soluble factors in response to extracellular viruses or virus mimics such as CpG-containing DNA. pDCs can also recognize live cells infected with certain RNA viruses, but the relevance and functional consequences of such recognition remain unclear. We studied the response of primary DCs to the prototypical persistent DNA virus, human cytomegalovirus (CMV). Human pDCs produced high amounts of type I interferon (IFN-I) when incubated with live CMV-infected fibroblasts but not with free CMV; the response involved integrin-mediated adhesion, transfer of DNA-containing virions to pDCs, and the recognition of DNA through TLR9. Compared with transient polyfunctional responses to CpG or free influenza virus, pDC response to CMV-infected cells was long-lasting, dominated by the production of IFN-I and IFN-III, and lacked diversification into functionally distinct populations. Similarly, pDC activation by influenza-infected lung epithelial cells was highly efficient, prolonged, and dominated by interferon production. Prolonged pDC activation by CMV-infected cells facilitated the activation of natural killer cells critical for CMV control. Last, patients with CMV viremia harbored phenotypically activated pDCs and increased circulating IFN-I and IFN-III. Thus, recognition of live infected cells is a mechanism of virus detection by pDCs that elicits a unique antiviral immune response.
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http://dx.doi.org/10.1126/sciimmunol.abc7302DOI Listing
April 2021

Autoantibody-mediated impairment of DNASE1L3 activity in sporadic systemic lupus erythematosus.

J Exp Med 2021 May;218(5)

Department of Pathology, New York University Grossman School of Medicine, New York, NY.

Antibodies to double-stranded DNA (dsDNA) are prevalent in systemic lupus erythematosus (SLE), particularly in patients with lupus nephritis, yet the nature and regulation of antigenic cell-free DNA (cfDNA) are poorly understood. Null mutations in the secreted DNase DNASE1L3 cause human monogenic SLE with anti-dsDNA autoreactivity. We report that >50% of sporadic SLE patients with nephritis manifested reduced DNASE1L3 activity in circulation, which was associated with neutralizing autoantibodies to DNASE1L3. These patients had normal total plasma cfDNA levels but showed accumulation of cfDNA in circulating microparticles. Microparticle-associated cfDNA contained a higher fraction of longer polynucleosomal cfDNA fragments, which bound autoantibodies with higher affinity than mononucleosomal fragments. Autoantibodies to DNASE1L3-sensitive antigens on microparticles were prevalent in SLE nephritis patients and correlated with the accumulation of cfDNA in microparticles and with disease severity. DNASE1L3-sensitive antigens included DNA-associated proteins such as HMGB1. Our results reveal autoantibody-mediated impairment of DNASE1L3 activity as a common nongenetic mechanism facilitating anti-dsDNA autoreactivity in patients with severe sporadic SLE.
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http://dx.doi.org/10.1084/jem.20201138DOI Listing
May 2021

TAO-kinase 3 governs the terminal differentiation of NOTCH2-dependent splenic conventional dendritic cells.

Proc Natl Acad Sci U S A 2020 12 19;117(49):31331-31342. Epub 2020 Nov 19.

Laboratory of Immunoregulation and Mucosal Immunology, VIB Center for Inflammation Research, 9000 Ghent, Belgium;

Antigen-presenting conventional dendritic cells (cDCs) are broadly divided into type 1 and type 2 subsets that further adapt their phenotype and function to perform specialized tasks in the immune system. The precise signals controlling tissue-specific adaptation and differentiation of cDCs are currently poorly understood. We found that mice deficient in the Ste20 kinase Thousand and One Kinase 3 (TAOK3) lacked terminally differentiated ESAM CD4 cDC2s in the spleen and failed to prime CD4 T cells in response to allogeneic red-blood-cell transfusion. These NOTCH2- and ADAM10-dependent cDC2s were absent selectively in the spleen, but not in the intestine of and mice. The loss of splenic ESAM cDC2s was cell-intrinsic and could be rescued by conditional overexpression of the constitutively active NOTCH intracellular domain in CD11c-expressing cells. Therefore, TAOK3 controls the terminal differentiation of NOTCH2-dependent splenic cDC2s.
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http://dx.doi.org/10.1073/pnas.2009847117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7733863PMC
December 2020

Plasma DNA Profile Associated with DNASE1L3 Gene Mutations: Clinical Observations, Relationships to Nuclease Substrate Preference, and In Vivo Correction.

Am J Hum Genet 2020 11 5;107(5):882-894. Epub 2020 Oct 5.

Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR, China; Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, China. Electronic address:

Plasma DNA fragmentomics is an emerging area in cell-free DNA diagnostics and research. In murine models, it has been shown that the extracellular DNase, DNASE1L3, plays a role in the fragmentation of plasma DNA. In humans, DNASE1L3 deficiency causes familial monogenic systemic lupus erythematosus with childhood onset and anti-dsDNA reactivity. In this study, we found that human patients with DNASE1L3 disease-associated gene variations showed aberrations in size and a reduction of a "CC" end motif of plasma DNA. Furthermore, we demonstrated that DNA from DNASE1L3-digested cell nuclei showed a median length of 153 bp with CC motif frequencies resembling plasma DNA from healthy individuals. Adeno-associated virus-based transduction of Dnase1l3 into Dnase1l3-deficient mice restored the end motif profiles to those seen in the plasma DNA of wild-type mice. Our findings demonstrate that DNASE1L3 is an important player in the fragmentation of plasma DNA, which appears to act in a cell-extrinsic manner to regulate plasma DNA size and motif frequency.
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http://dx.doi.org/10.1016/j.ajhg.2020.09.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7674998PMC
November 2020

Intravital Imaging Reveals Motility of Adult Hematopoietic Stem Cells in the Bone Marrow Niche.

Cell Stem Cell 2020 08 25;27(2):336-345.e4. Epub 2020 Jun 25.

Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA. Electronic address:

Adult mammalian hematopoietic stem cells (HSCs) reside in the bone marrow (BM) but can be mobilized into blood for use in transplantation. HSCs interact with BM niche cells that produce growth factor c-Kit ligand (Kitl/SCF) and chemokine CXCL12, and were thought to be static and sessile. We used two-photon laser scanning microscopy to visualize genetically labeled HSCs in the BM of live mice for several hours. The majority of HSCs showed a dynamic non-spherical morphology and significant motility, undergoing slow processive motion interrupted by short stretches of confined motion. HSCs moved in the perivascular space and showed intermittent close contacts with SCF-expressing perivascular stromal cells. In contrast, mobilization-inducing blockade of CXCL12 receptor CXCR4 and integrins rapidly abrogated HSC motility and shape dynamics in real time. Our results reveal an unexpectedly dynamic nature of HSC residence in the BM and interaction with the SCF stromal niche, which is disrupted during HSC mobilization.
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http://dx.doi.org/10.1016/j.stem.2020.06.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7415613PMC
August 2020

The Source and Dynamics of Adult Hematopoiesis: Insights from Lineage Tracing.

Annu Rev Cell Dev Biol 2020 10 24;36:529-550. Epub 2020 Jun 24.

Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA; email:

The generation of all blood cell lineages (hematopoiesis) is sustained throughout the entire life span of adult mammals. Studies using cell transplantation identified the self-renewing, multipotent hematopoietic stem cells (HSCs) as the source of hematopoiesis in adoptive hosts and delineated a hierarchy of HSC-derived progenitors that ultimately yield mature blood cells. However, much less is known about adult hematopoiesis as it occurs in native hosts, i.e., without transplantation. Here we review recent advances in our understanding of native hematopoiesis, focusing in particular on the application of genetic lineage tracing in mice. The emerging evidence has established HSCs as the major source of native hematopoiesis, helped to define the kinetics of HSC differentiation, and begun exploring native hematopoiesis in stress conditions such as aging and inflammation. Major outstanding questions about native hematopoiesis still remain, such as its clonal composition, the nature of lineage commitment, and the dynamics of the process in humans.
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http://dx.doi.org/10.1146/annurev-cellbio-020520-114601DOI Listing
October 2020

Plasmacytoid Dendritic Cells and Type I Interferon Promote Extrafollicular B Cell Responses to Extracellular Self-DNA.

Immunity 2020 06 25;52(6):1022-1038.e7. Epub 2020 May 25.

Department of Pathology, New York University Grossman School of Medicine, New York, NY 10016, USA; Department of Medicine, New York University Grossman School of Medicine, New York, NY 10016, USA. Electronic address:

Class-switched antibodies to double-stranded DNA (dsDNA) are prevalent and pathogenic in systemic lupus erythematosus (SLE), yet mechanisms of their development remain poorly understood. Humans and mice lacking secreted DNase DNASE1L3 develop rapid anti-dsDNA antibody responses and SLE-like disease. We report that anti-DNA responses in Dnase1l3 mice require CD40L-mediated T cell help, but proceed independently of germinal center formation via short-lived antibody-forming cells (AFCs) localized to extrafollicular regions. Type I interferon (IFN-I) signaling and IFN-I-producing plasmacytoid dendritic cells (pDCs) facilitate the differentiation of DNA-reactive AFCs in vivo and in vitro and are required for downstream manifestations of autoimmunity. Moreover, the endosomal DNA sensor TLR9 promotes anti-dsDNA responses and SLE-like disease in Dnase1l3 mice redundantly with another nucleic acid-sensing receptor, TLR7. These results establish extrafollicular B cell differentiation into short-lived AFCs as a key mechanism of anti-DNA autoreactivity and reveal a major contribution of pDCs, endosomal Toll-like receptors (TLRs), and IFN-I to this pathway.
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http://dx.doi.org/10.1016/j.immuni.2020.04.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7306002PMC
June 2020

A conserved dendritic-cell regulatory program limits antitumour immunity.

Nature 2020 04 25;580(7802):257-262. Epub 2020 Mar 25.

The Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Checkpoint blockade therapies have improved cancer treatment, but such immunotherapy regimens fail in a large subset of patients. Conventional type 1 dendritic cells (DC1s) control the response to checkpoint blockade in preclinical models and are associated with better overall survival in patients with cancer, reflecting the specialized ability of these cells to prime the responses of CD8 T cells. Paradoxically, however, DC1s can be found in tumours that resist checkpoint blockade, suggesting that the functions of these cells may be altered in some lesions. Here, using single-cell RNA sequencing in human and mouse non-small-cell lung cancers, we identify a cluster of dendritic cells (DCs) that we name 'mature DCs enriched in immunoregulatory molecules' (mregDCs), owing to their coexpression of immunoregulatory genes (Cd274, Pdcd1lg2 and Cd200) and maturation genes (Cd40, Ccr7 and Il12b). We find that the mregDC program is expressed by canonical DC1s and DC2s upon uptake of tumour antigens. We further find that upregulation of the programmed death ligand 1 protein-a key checkpoint molecule-in mregDCs is induced by the receptor tyrosine kinase AXL, while upregulation of interleukin (IL)-12 depends strictly on interferon-γ and is controlled negatively by IL-4 signalling. Blocking IL-4 enhances IL-12 production by tumour-antigen-bearing mregDC1s, expands the pool of tumour-infiltrating effector T cells and reduces tumour burden. We have therefore uncovered a regulatory module associated with tumour-antigen uptake that reduces DC1 functionality in human and mouse cancers.
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http://dx.doi.org/10.1038/s41586-020-2134-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7787191PMC
April 2020

Identification of a nerve-associated, lung-resident interstitial macrophage subset with distinct localization and immunoregulatory properties.

Sci Immunol 2020 03;5(45)

Department of Microbiology, New York University Langone Health, New York, NY 10016, USA.

Tissue-resident macrophages are a diverse population of cells that perform specialized functions including sustaining tissue homeostasis and tissue surveillance. Here, we report an interstitial subset of CD169 lung-resident macrophages that are transcriptionally and developmentally distinct from alveolar macrophages (AMs). They are primarily localized around the airways and are found in close proximity to the sympathetic nerves in the bronchovascular bundle. These nerve- and airway-associated macrophages (NAMs) are tissue resident, yolk sac derived, self-renewing, and do not require CCR2 monocytes for development or maintenance. Unlike AMs, the development of NAMs requires CSF1 but not GM-CSF. Bulk population and single-cell transcriptome analysis indicated that NAMs are distinct from other lung-resident macrophage subsets and highly express immunoregulatory genes under steady-state and inflammatory conditions. NAMs proliferated robustly after influenza infection and activation with the TLR3 ligand poly(I:C), and in their absence, the inflammatory response was augmented, resulting in excessive production of inflammatory cytokines and innate immune cell infiltration. Overall, our study provides insights into a distinct subset of airway-associated pulmonary macrophages that function to maintain immune and tissue homeostasis.
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http://dx.doi.org/10.1126/sciimmunol.aax8756DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7717505PMC
March 2020

Integrated Cross-Species Analysis Identifies a Conserved Transitional Dendritic Cell Population.

Cell Rep 2019 12;29(11):3736-3750.e8

Microbiology & Immunology Department and Immunology Program, Stanford University School of Medicine, Stanford, CA 94305, USA. Electronic address:

Plasmacytoid dendritic cells (pDCs) are sensor cells with diverse immune functions, from type I interferon (IFN-I) production to antigen presentation, T cell activation, and tolerance. Regulation of these functions remains poorly understood but could be mediated by functionally specialized pDC subpopulations. We address pDC diversity using a high-dimensional single-cell approach: mass cytometry (CyTOF). Our analysis uncovers a murine pDC-like population that specializes in antigen presentation with limited capacity for IFN-I production. Using a multifaceted cross-species comparison, we show that this pDC-like population is the definitive murine equivalent of the recently described human AXL DCs, which we unify under the name transitional DCs (tDCs) given their continuum of pDC and cDC2 characteristics. tDCs share developmental traits with pDCs, as well as recruitment dynamics during viral infection. Altogether, we provide a framework for deciphering the function of pDCs and tDCs during diseases, which has the potential to open new avenues for therapeutic design.
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http://dx.doi.org/10.1016/j.celrep.2019.11.042DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6951814PMC
December 2019

The Specificity of Conditional Gene Targeting: A Case for Cre Reporters.

Authors:
Boris Reizis

Immunity 2019 10;51(4):593-594

Department of Pathology, New York University School of Medicine, New York, NY 10016, USA. Electronic address:

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http://dx.doi.org/10.1016/j.immuni.2019.09.009DOI Listing
October 2019

Self-DNA at the Epicenter of SLE: Immunogenic Forms, Regulation, and Effects.

Front Immunol 2019 10;10:1601. Epub 2019 Jul 10.

Department of Pathology, New York University School of Medicine, New York, NY, United States.

Self-reactive B cells generated through V(D)J recombination in the bone marrow or through accrual of random mutations in secondary lymphoid tissues are mostly purged or edited to prevent autoimmunity. Yet, 10-20% of all mature naïve B cells in healthy individuals have self-reactive B cell receptors (BCRs). In patients with serologically active systemic lupus erythematosus (SLE) the percentage increases up to 50%, with significant self-DNA reactivity that correlates with disease severity. Endogenous or self-DNA has emerged as a potent antigen in several autoimmune disorders, particularly in SLE. However, the mechanism(s) regulating or preventing anti-DNA antibody production remain elusive. It is likely that in healthy subjects, DNA-reactive B cells avoid activation due to the unavailability of endogenous DNA, which is efficiently degraded through efferocytosis and various DNA-processing proteins. Genetic defects, physiological, and/or pathological conditions can override these protective checkpoints, leading to autoimmunity. Plausibly, increased availability of immunogenic self-DNA may be the key initiating event in the loss of tolerance of otherwise quiescent DNA-reactive B cells. Indeed, mutations impairing apoptotic cell clearance pathways and nucleic acid metabolism-associated genes like DNases, RNases, and their sensors are known to cause autoimmune disorders including SLE. Here we review the literature supporting the idea that increased availability of DNA as an immunogen or adjuvant, or both, may cause the production of pathogenic anti-DNA antibodies and subsequent manifestations of clinical disease such as SLE. We discuss the main cellular players involved in anti-DNA responses; the physical forms and sources of immunogenic DNA in autoimmunity; the DNA-protein complexes that render DNA immunogenic; the regulation of DNA availability by intracellular and extracellular DNases and the autoimmune pathologies associated with their dysfunction; the cytosolic and endosomal sensors of immunogenic DNA; and the cytokines such as interferons that drive auto-inflammatory and autoimmune pathways leading to clinical disease. We propose that prevention of DNA availability by aiding extracellular DNase activity could be a viable therapeutic modality in controlling SLE.
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http://dx.doi.org/10.3389/fimmu.2019.01601DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6637313PMC
October 2020

Thioesterase PPT1 balances viral resistance and efficient T cell crosspriming in dendritic cells.

J Exp Med 2019 09 1;216(9):2091-2112. Epub 2019 Jul 1.

Department of Immunology, Sun Yat-sen University Zhongshan School of Medicine, Guangzhou, Guangdong, China

Conventional type 1 dendritic cells (cDC1s) are inherently resistant to many viruses but, paradoxically, possess fewer acidic phagosomes that enable antigen retention and cross-presentation. We report that palmitoyl-protein thioesterase 1 (PPT1), which catabolizes lipid-modified proteins in neurons, is highly expressed in cDC1s. PPT1-deficient DCs are more susceptible to vesicular stomatitis virus (VSV) infection, and mice with PPT1 deficiency in cDC1s show impaired response to VSV. Conversely, PPT1-deficient cDC1s enhance the priming of naive CD8 T cells into tissue-resident KLRG1 effectors and memory T cells, resulting in rapid clearance of tumors and Mechanistically, PPT1 protects steady state DCs from viruses by promoting antigen degradation and endosomal acidification via V-ATPase recruitment. After DC activation, immediate down-regulation of PPT1 is likely to facilitate efficient cross-presentation, production of costimulatory molecules and inflammatory cytokines. Thus, PPT1 acts as a molecular rheostat that allows cDC1s to crossprime efficiently without compromising viral resistance. These results suggest potential therapeutics to enhance cDC1-dependent crosspriming.
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http://dx.doi.org/10.1084/jem.20190041DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6719428PMC
September 2019

Plasmacytoid Dendritic Cells: Development, Regulation, and Function.

Authors:
Boris Reizis

Immunity 2019 01;50(1):37-50

Department of Pathology and Department of Medicine, New York University School of Medicine, New York, NY 10016, USA. Electronic address:

Plasmacytoid dendritic cells (pDCs) are a unique sentinel cell type that can detect pathogen-derived nucleic acids and respond with rapid and massive production of type I interferon. This review summarizes our current understanding of pDC biology, including transcriptional regulation, heterogeneity, role in antiviral immune responses, and involvement in immune pathology, particularly in autoimmune diseases, immunodeficiency, and cancer. We also highlight the remaining gaps in our knowledge and important questions for the field, such as the molecular basis of unique interferon-producing capacity of pDCs. A better understanding of cell type-specific positive and negative control of pDC function should pave the way for translational applications focused on this immune cell type.
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http://dx.doi.org/10.1016/j.immuni.2018.12.027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6342491PMC
January 2019

deletion causes aberrations in length and end-motif frequencies in plasma DNA.

Proc Natl Acad Sci U S A 2019 01 28;116(2):641-649. Epub 2018 Dec 28.

Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China;

Circulating DNA in plasma consists of short DNA fragments. The biological processes generating such fragments are not well understood. DNASE1L3 is a secreted DNASE1-like nuclease capable of digesting DNA in chromatin, and its absence causes anti-DNA responses and autoimmunity in humans and mice. We found that the deletion of in mice resulted in aberrations in the fragmentation of plasma DNA. Such aberrations included an increase in short DNA molecules below 120 bp, which was positively correlated with anti-DNA antibody levels. We also observed an increase in long, multinucleosomal DNA molecules and decreased frequencies of the most common end motifs found in plasma DNA. These aberrations were independent of anti-DNA response, suggesting that they represented a primary effect of DNASE1L3 loss. Pregnant mice carrying fetuses showed a partial restoration of normal frequencies of plasma DNA end motifs, suggesting that DNASE1L3 from -proficient fetuses could enter maternal systemic circulation and affect both fetal and maternal DNA fragmentation in a systemic as well as local manner. However, the observed shortening of circulating fetal DNA relative to maternal DNA was not affected by the deletion of Collectively, our findings demonstrate that DNASE1L3 plays a role in circulating plasma DNA homeostasis by enhancing fragmentation and influencing end-motif frequencies. These results support a distinct role of DNASE1L3 as a regulator of the physical form and availability of cell-free DNA and may have important implications for the mechanism whereby this enzyme prevents autoimmunity.
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http://dx.doi.org/10.1073/pnas.1815031116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6329986PMC
January 2019

Plasmacytoid Dendritic Cells Are Largely Dispensable for the Pathogenesis of Experimental Inflammatory Bowel Disease.

Front Immunol 2018 25;9:2475. Epub 2018 Oct 25.

Department of Pathology, New York University School of Medicine, New York, NY, United States.

Inflammatory bowel disease (IBD) is a chronic inflammatory condition caused by an aberrant immune response to microbial components of the gastrointestinal tract. Plasmacytoid dendritic cells (pDCs) are innate immune cells specialized in the production of type I interferons and were recently implicated in the pathogenesis of autoimmune disorders such as lupus and scleroderma. While pDCs were shown to infiltrate intestinal mucosa of IBD patients and proposed to participate in intestinal inflammation, their net contribution to the disease remains unclear. We addressed this question by targeting the pDC-specific transcription factor TCF4 (E2-2) in experimental IBD caused by deficiency of Wiskott-Aldrich syndrome protein (WASP) or of interleukin-10 (IL-10). Monoallelic deletion, which was previously shown to abrogate experimental lupus, did not affect autoimmunity manifestations or colitis in WASP-deficient animals. Furthermore, conditional biallelic targeting resulted in a near-complete pDC ablation, yet had no effect on the development of colitis in IL-10-deficient mice. Our results suggest that, in contrast to other inflammatory and autoimmune diseases, pDCs do not play a major role in the pathogenesis of intestinal inflammation during IBD.
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http://dx.doi.org/10.3389/fimmu.2018.02475DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6209677PMC
September 2019

Kinetics of adult hematopoietic stem cell differentiation in vivo.

J Exp Med 2018 11 5;215(11):2815-2832. Epub 2018 Oct 5.

Department of Pathology, New York University School of Medicine, New York, NY

Adult hematopoiesis has been studied in terms of progenitor differentiation potentials, whereas its kinetics in vivo is poorly understood. We combined inducible lineage tracing of endogenous adult hematopoietic stem cells (HSCs) with flow cytometry and single-cell RNA sequencing to characterize early steps of hematopoietic differentiation in the steady-state. Labeled cells, comprising primarily long-term HSCs and some short-term HSCs, produced megakaryocytic lineage progeny within 1 wk in a process that required only two to three cell divisions. Erythroid and myeloid progeny emerged simultaneously by 2 wk and included a progenitor population with expression features of both lineages. Myeloid progenitors at this stage showed diversification into granulocytic, monocytic, and dendritic cell types, and rare intermediate cell states could be detected. In contrast, lymphoid differentiation was virtually absent within the first 3 wk of tracing. These results show that continuous differentiation of HSCs rapidly produces major hematopoietic lineages and cell types and reveal fundamental kinetic differences between megakaryocytic, erythroid, myeloid, and lymphoid differentiation.
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http://dx.doi.org/10.1084/jem.20180136DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6219744PMC
November 2018

DNA as a self-antigen: nature and regulation.

Curr Opin Immunol 2018 12 24;55:31-37. Epub 2018 Sep 24.

Department of Pathology, New York University School of Medicine, New York, NY 10016, USA; Department of Medicine, New York University School of Medicine, New York, NY 10016, USA. Electronic address:

High-affinity antibodies to double-stranded DNA are a hallmark of systemic lupus erythematosus (SLE) and are thought to contribute to disease flares and tissue inflammation such as nephritis. Notwithstanding their clinical importance, major questions remain about the development and regulation of these pathogenic anti-DNA responses. These include the mechanisms that prevent anti-DNA responses in healthy subjects, despite the constant generation of self-DNA and the abundance of DNA-reactive B cells; the nature and physical form of antigenic DNA in SLE; the regulation of DNA availability as an antigen; and potential therapeutic strategies targeting the pathogenic DNA in SLE. This review summarizes current progress in these directions, focusing on the role of secreted DNases in the regulation of antigenic extracellular DNA.
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http://dx.doi.org/10.1016/j.coi.2018.09.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6317730PMC
December 2018

Transcription factor Etv6 regulates functional differentiation of cross-presenting classical dendritic cells.

J Exp Med 2018 09 7;215(9):2265-2278. Epub 2018 Aug 7.

Department of Pathology, New York University School of Medicine, New York, NY

An IRF8-dependent subset of conventional dendritic cells (cDCs), termed cDC1, effectively cross-primes CD8 T cells and facilitates tumor-specific T cell responses. Etv6 is an ETS family transcription factor that controls hematopoietic stem and progenitor cell (HSPC) function and thrombopoiesis. We report that like HSPCs, cDCs express Etv6, but not its antagonist, ETS1, whereas interferon-producing plasmacytoid dendritic cells (pDCs) express both factors. Deletion of Etv6 in the bone marrow impaired the generation of cDC1-like cells in vitro and abolished the expression of signature marker CD8α on cDC1 in vivo. Moreover, Etv6-deficient primary cDC1 showed a partial reduction of cDC-specific and cDC1-specific gene expression and chromatin signatures and an aberrant up-regulation of pDC-specific signatures. Accordingly, DC-specific Etv6 deletion impaired CD8 T cell cross-priming and the generation of tumor antigen-specific CD8 T cells. Thus, Etv6 optimizes the resolution of cDC1 and pDC expression programs and the functional fitness of cDC1, thereby facilitating T cell cross-priming and tumor-specific responses.
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http://dx.doi.org/10.1084/jem.20172323DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6122974PMC
September 2018

The Transcription Factor Zfx Regulates Peripheral T Cell Self-Renewal and Proliferation.

Front Immunol 2018 4;9:1482. Epub 2018 Jul 4.

Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, United States.

Peripheral T lymphocytes share many functional properties with hematopoietic stem cells (HSCs), including long-term maintenance, quiescence, and latent proliferative potential. In addition, peripheral T cells retain the capacity for further differentiation into a variety of subsets, much like HSCs. While the similarities between T cells and HSC have long been hypothesized, the potential common genetic regulation of HSCs and T cells has not been widely explored. We have studied the T cell-intrinsic role of , a transcription factor specifically required for HSC maintenance. We report that T cell-specific deletion of caused age-dependent depletion of naïve peripheral T cells. -deficient T cells also failed to undergo homeostatic proliferation in a lymphopenic environment, and showed impaired antigen-specific expansion and memory response. In addition, the invariant natural killer T cell compartment was severely reduced. RNA-Seq analysis revealed that the most dysregulated genes in Zfx-deficient T cells were similar to those observed in Zfx-deficient HSC and B cells. These studies identify as an important regulator of peripheral T cell maintenance and expansion and highlight the common molecular basis of HSC and lymphocyte homeostasis.
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http://dx.doi.org/10.3389/fimmu.2018.01482DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6039547PMC
July 2018

Notch Signaling Facilitates In Vitro Generation of Cross-Presenting Classical Dendritic Cells.

Cell Rep 2018 06;23(12):3658-3672.e6

Department of Pathology, New York University School of Medicine, New York, NY 10016, USA; Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY 10032, USA. Electronic address:

The IRF8-dependent subset of classical dendritic cells (cDCs), termed cDC1, is important for cross-priming cytotoxic T cell responses against pathogens and tumors. Culture of hematopoietic progenitors with DC growth factor FLT3 ligand (FLT3L) yields very few cDC1s (in humans) or only immature "cDC1-like" cells (in the mouse). We report that OP9 stromal cells expressing the Notch ligand Delta-like 1 (OP9-DL1) optimize FLT3L-driven development of cDC1s from murine immortalized progenitors and primary bone marrow cells. Co-culture with OP9-DL1 induced IRF8-dependent cDC1s with a phenotype (CD103 Dec205 CD8α) and expression profile resembling primary splenic cDC1s. OP9-DL1-induced cDC1s showed preferential migration toward CCR7 ligands in vitro and superior T cell cross-priming and antitumor vaccination in vivo. Co-culture with OP9-DL1 also greatly increased the yield of IRF8-dependent CD141 cDC1s from human bone marrow progenitors cultured with FLT3L. Thus, Notch signaling optimizes cDC generation in vitro and yields authentic cDC1s for functional studies and translational applications.
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http://dx.doi.org/10.1016/j.celrep.2018.05.068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6063084PMC
June 2018

Metabolic control of cell fate bifurcations in a hematopoietic progenitor population.

Immunol Cell Biol 2018 09 6;96(8):863-871. Epub 2018 Apr 6.

Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA.

Growth signals drive hematopoietic progenitor cells to proliferate and branch into divergent cell fates, but how unequal outcomes arise from a common progenitor is not fully understood. We used steady-state analysis of in vivo hematopoiesis and Fms-related tyrosine kinase 3 ligand (Flt3L)-induced in vitro differentiation of dendritic cells (DCs) to determine how growth signals regulate lineage bias. We found that Flt3L signaling induced anabolic activation and proliferation of DC progenitors, which was associated with DC differentiation. Perturbation of processes associated with quiescence and catabolism, including AMP-activated protein kinase signaling, fatty acid oxidation, or mitochondrial clearance increased development of cDC2 cells at the expense of cDC1 cells. Conversely, scavenging anabolism-associated reactive oxygen species skewed differentiation toward cDC1 cells. Sibling daughter cells of dividing DC progenitors exhibited unequal expression of the transcription factor interferon regulatory factor 8, which correlated with clonal divergence in FoxO3a signaling and population-level bifurcation of cell fate. We propose that unequal transmission of growth signals during cell division might support fate branches during proliferative expansion of progenitors.
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http://dx.doi.org/10.1111/imcb.12040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6146018PMC
September 2018

New genetic tools for the in vivo study of hematopoietic stem cell function.

Exp Hematol 2018 05 6;61:26-35. Epub 2018 Mar 6.

ACTION Laboratory, INSERM Unit 1218, University of Bordeaux, Bordeaux, France. Electronic address:

The production of blood cells is dependent on the activity of a rare stem cell population that normally resides in the bone marrow (BM) of the organism. These hematopoietic stem cells (HSCs) have the ability to both self-renew and differentiate, ensuring this lifelong hematopoiesis. Determining the regulation of HSC functions should thus provide critical insight to advancing regenerative medicine. Until quite recently, HSCs were primarily studied using in vitro studies and transplantations into immunodeficient hosts. Indeed, the definition of a bona fide HSC is its ability to reconstitute lymphopenic hosts. In this review, we discuss the development of novel, HSC-specific genetic reporter systems that enable the prospective identification of HSCs and the study of their functions in the absence of transplantation. Coupled with additional technological advances, these studies are now defining the fundamental properties of HSCs in vivo. Furthermore, complex cellular and molecular mechanisms that regulate HSC dormancy, self-renewal, and differentiation are being identified and further dissected. These novel reporter systems represent a major technological advance for the stem cell field and allow new questions to be addressed.
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http://dx.doi.org/10.1016/j.exphem.2018.02.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5899657PMC
May 2018

Chronic In Vivo Interaction of Dendritic Cells Expressing the Ligand Rae-1ε with NK Cells Impacts NKG2D Expression and Function.

Immunohorizons 2017 May;1(3):10-19

Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143.

To investigate how dendritic cells (DCs) interact with NK cells in vivo, we developed a novel mouse model in which Rae-1ε, a ligand of the NKG2D receptor, is expressed in cells with high levels of CD11c. In these CD11c-Rae1 mice, expression of Rae-1 was confirmed on all subsets of DCs and a small subset of B and T cells, but not on NK cells. DC numbers and activation status were unchanged, and NK cells in these CD11c-Rae1 mice presented the same Ly49 repertoire and maturation levels as their littermate wildtype controls. Early NK cell activation after mouse CMV infection was slightly lower than in wildtype mice, but NK cell expansion and viral control were comparable. Notably, we demonstrate that chronic interaction of NK cells with NKG2D ligand-expressing DCs leads to a reversible NKG2D down-modulation, as well as impaired NKG2D-dependent NK cell functions, including tumor rejection. In addition to generating a useful mouse model, our studies reveal in vivo the functional importance of the NK cell and DC cross-talk.
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http://dx.doi.org/10.4049/immunohorizons.1700004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5555644PMC
May 2017

RelB Steady-State Migratory Dendritic Cells Control the Peripheral Pool of the Natural Foxp3 Regulatory T Cells.

Front Immunol 2017 22;8:726. Epub 2017 Jun 22.

Institute for Virology and Immunobiology, University of Würzburg, Würzburg, Germany.

Thymus-derived natural Foxp3 CD4 regulatory T cells (nTregs) play a key role in maintaining immune tolerance and preventing autoimmune disease. Several studies indicate that dendritic cells (DCs) are critically involved in the maintenance and proliferation of nTregs. However, the mechanisms how DCs manage to keep the peripheral pool at constant levels remain poorly understood. Here, we describe that the NF-κB/Rel family transcription factor RelB controls the frequencies of steady-state migratory DCs (ssmDCs) in peripheral lymph nodes and their numbers control peripheral nTreg homeostasis. DC-specific RelB depletion was investigated in CD11c-Cre × RelB mice (RelB), which showed normal frequencies of resident DCs in lymph nodes and spleen while the subsets of CD103 Langerin dermal DCs (dDCs) and Langerhans cells but not CD103 Langerin dDC of the ssmDCs in skin-draining lymph nodes were increased. Enhanced frequencies and proliferation rates were also observed for nTregs and a small population of CD4 CD44 CD25 memory-like T cells (Tml). Interestingly, only the Tml but not DCs showed an increase in IL-2-producing capacity in lymph nodes of RelB mice. Blocking of IL-2 reduced the frequency of nTregs but increased the Tml frequencies, followed by a recovery of nTregs. Taken together, by employing RelB mice with increased frequencies of ssmDCs our data indicate a critical role for specific ssmDC subsets for the peripheral nTreg and IL-2 Tml frequencies during homeostasis.
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http://dx.doi.org/10.3389/fimmu.2017.00726DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5479892PMC
June 2017

Gut homeostasis and regulatory T cell induction depend on molecular chaperone gp96 in CD11c cells.

Sci Rep 2017 05 19;7(1):2171. Epub 2017 May 19.

Department of Microbiology and Immunology, Hollings Cancer Center, Medical University of South Carolina, Charleston, South Carolina, United States.

The intestinal immunity and tolerance are orchestrated by both the innate and the adaptive immune system. Intestinal professional antigen presenting cells (pAPCs) recognize and respond to the gut microbiota through multiple pattern-recognition receptors, including TLRs and NLRs. How gut pAPCs maintain mucosal homeostasis remains incompletely understood. Heat shock protein gp96, also known as grp94, is an essential immune chaperone for TLRs. However, the role of gp96 in regulating CD11c APCs in the gut immunity and tolerance is unknown. By a genetic strategy, we report here that selective deletion of gp96 from CD11c cells in mice results in alteration of dendritic cell and T cell subsets in the gut as well as loss of antigen-specific regulatory T cell induction in the mesenteric lymph nodes. Strikingly, these conditional gp96-null mice developed spontaneous colitis, had increased levels of systemic and fecal IgA, and were highly susceptible to chemical-induced colitis. Our findings for the first time demonstrate that gp96 is essential for CD11c cells to induce regulatory T cells and maintain gut homeostasis, illustrating the importance of protein immune chaperone in safeguarding against immune pathology.
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http://dx.doi.org/10.1038/s41598-017-02415-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5438351PMC
May 2017

Dendritic Cells Display Subset and Tissue-Specific Maturation Dynamics over Human Life.

Immunity 2017 03;46(3):504-515

Columbia Center for Translational Immunology, Columbia University Medical Center, New York, NY 10032, USA; Department of Surgery, Columbia University Medical Center, New York, NY 10032, USA; Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY 10032, USA. Electronic address:

Maturation and migration to lymph nodes (LNs) constitutes a central paradigm in conventional dendritic cell (cDC) biology but remains poorly defined in humans. Using our organ donor tissue resource, we analyzed cDC subset distribution, maturation, and migration in mucosal tissues (lungs, intestines), associated lymph nodes (LNs), and other lymphoid sites from 78 individuals ranging from less than 1 year to 93 years of age. The distribution of cDC1 (CD141CD13) and cDC2 (Sirp-αCD1c) subsets was a function of tissue site and was conserved between donors. We identified cDC2 as the major mature (HLA-DR) subset in LNs with the highest frequency in lung-draining LNs. Mature cDC2 in mucosal-draining LNs expressed tissue-specific markers derived from the paired mucosal site, reflecting their tissue-migratory origin. These distribution and maturation patterns were largely maintained throughout life, with site-specific variations. Our findings provide evidence for localized DC tissue surveillance and reveal a lifelong division of labor between DC subsets, with cDC2 functioning as guardians of the mucosa.
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http://dx.doi.org/10.1016/j.immuni.2017.02.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5415308PMC
March 2017

Oral Prion Disease Pathogenesis Is Impeded in the Specific Absence of CXCR5-Expressing Dendritic Cells.

J Virol 2017 05 28;91(10). Epub 2017 Apr 28.

The Roslin Institute and Royal (Dick) School of Veterinary Sciences, University of Edinburgh, Easter Bush, United Kingdom

After oral exposure, the early replication of certain prion strains upon stromal cell-derived follicular dendritic cells (FDC) in the Peyer's patches in the small intestine is essential for the efficient spread of disease to the brain. However, little is known of how prions are initially conveyed from the gut lumen to establish infection on FDC. Our previous data suggest that mononuclear phagocytes such as CD11c conventional dendritic cells play an important role in the initial propagation of prions from the gut lumen into Peyer's patches. However, whether these cells conveyed orally acquired prions toward FDC within Peyer's patches was not known. The chemokine CXCL13 is expressed by FDC and follicular stromal cells and modulates the homing of CXCR5-expressing cells toward the FDC-containing B cell follicles. Here, novel compound transgenic mice were created in which a CXCR5 deficiency was specifically restricted to CD11c cells. These mice were used to determine whether CXCR5-expressing conventional dendritic cells propagate prions toward FDC after oral exposure. Our data show that in the specific absence of CXCR5-expressing conventional dendritic cells the early accumulation of prions upon FDC in Peyer's patches and the spleen was impaired, and disease susceptibility significantly reduced. These data suggest that CXCR5-expressing conventional dendritic cells play an important role in the efficient propagation of orally administered prions toward FDC within Peyer's patches in order to establish host infection. Many natural prion diseases are acquired by oral consumption of contaminated food or pasture. Once the prions reach the brain they cause extensive neurodegeneration, which ultimately leads to death. In order for the prions to efficiently spread from the gut to the brain, they first replicate upon follicular dendritic cells within intestinal Peyer's patches. How the prions are first delivered to follicular dendritic cells to establish infection was unknown. Understanding this process is important since treatments which prevent prions from infecting follicular dendritic cells can block their spread to the brain. We created mice in which mobile conventional dendritic cells were unable to migrate toward follicular dendritic cells. In these mice the early accumulation of prions on follicular dendritic cells was impaired and oral prion disease susceptibility was reduced. This suggests that prions exploit conventional dendritic cells to facilitate their initial delivery toward follicular dendritic cells to establish host infection.
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http://dx.doi.org/10.1128/JVI.00124-17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5411578PMC
May 2017

TGF-β inhibitor Smad7 regulates dendritic cell-induced autoimmunity.

Proc Natl Acad Sci U S A 2017 02 6;114(8):E1480-E1489. Epub 2017 Feb 6.

Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg University Mainz, 55131 Mainz, Germany;

TGF-β is an anti-inflammatory cytokine whose signaling is negatively controlled by Smad7. Previously, we established a role for Smad7 in the generation of autoreactive T cells; however, the function of Smad7 in dendritic cells (DCs) remains elusive. Here, we demonstrate that DC-specific Smad7 deficiency resulted in elevated expression of the transcription factors Batf3 and IRF8, leading to increased frequencies of CD8CD103 DCs in the spleen. Furthermore, Smad7-deficient DCs expressed higher levels of indoleamine 2,3-dioxygenase (IDO), an enzyme associated with tolerance induction. Mice devoid of Smad7 specifically in DCs are resistant to the development of experimental autoimmune encephalomyelitis (EAE) as a result of an increase of protective regulatory T cells (Tregs) and reduction of encephalitogenic effector T cells in the central nervous system. In agreement, inhibition of IDO activity or depletion of Tregs restored disease susceptibility. Intriguingly, when Smad7-deficient DCs also lacked the IFN-γ receptor, the mice regained susceptibility to EAE, demonstrating that IFN-γ signaling in DCs mediates their tolerogenic function. Our data indicate that Smad7 expression governs splenic DC subset differentiation and is critical for the promotion of their efficient function in immunity.
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http://dx.doi.org/10.1073/pnas.1615065114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5338403PMC
February 2017