1
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Mishra H, Schlack-Leigers C, Lim EL, Thieck O, Magg T, Raedler J, Wolf C, Klein C, Ewers H, Lee-Kirsch MA, Meierhofer D, Hauck F, Majer O. Disrupted degradative sorting of TLR7 is associated with human lupus. Sci Immunol 2024; 9:eadi9575. [PMID: 38207015 DOI: 10.1126/sciimmunol.adi9575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 12/22/2023] [Indexed: 01/13/2024]
Abstract
Hyperactive TLR7 signaling has long been appreciated as driver of autoimmune disease in mouse models. Recently, gain-of-function mutations in TLR7 were identified as a monogenic cause of human lupus. TLR7 is an intracellular transmembrane receptor, sensing RNA breakdown products within late endosomes. Here, we show that endosome dysfunction leads to unrestricted TLR7 signaling and is associated with human lupus. The late endosomal BORC complex together with the small GTPase Arl8b controls intracellular TLR7 levels by regulating receptor turnover. This requires a direct interaction between the TLR7-associated trafficking factor Unc93b1 and Arl8b. We identified an UNC93B1 mutation in a patient with childhood-onset lupus, which results in reduced BORC interaction and endosomal TLR7 accumulation. Therefore, a failure to control TLR7 turnover is sufficient to break immunological tolerance to nucleic acids. Our results highlight the importance of an intact endomembrane system in preventing pathological TLR7 signaling and autoimmune disease.
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Affiliation(s)
- Harshita Mishra
- Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Claire Schlack-Leigers
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin 14195, Germany
| | - Ee Lyn Lim
- Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Oliver Thieck
- Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Thomas Magg
- Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München, Munich 80337, Germany
| | - Johannes Raedler
- Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München, Munich 80337, Germany
| | - Christine Wolf
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany
| | - Christoph Klein
- Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München, Munich 80337, Germany
| | - Helge Ewers
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, Berlin 14195, Germany
| | - Min Ae Lee-Kirsch
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Berlin 14195, Germany
| | - Fabian Hauck
- Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München, Munich 80337, Germany
| | - Olivia Majer
- Max Planck Institute for Infection Biology, Berlin 10117, Germany
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2
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Wolf C, Lim EL, Mokhtari M, Kind B, Odainic A, Lara-Villacanas E, Koss S, Mages S, Menzel K, Engel K, Dückers G, Bernbeck B, Schneider DT, Siepermann K, Niehues T, Goetzke CC, Durek P, Minden K, Dörner T, Stittrich A, Szelinski F, Guerra GM, Massoud M, Bieringer M, de Oliveira Mann CC, Beltrán E, Kallinich T, Mashreghi MF, Schmidt SV, Latz E, Klughammer J, Majer O, Lee-Kirsch MA. UNC93B1 variants underlie TLR7-dependent autoimmunity. Sci Immunol 2024; 9:eadi9769. [PMID: 38207055 DOI: 10.1126/sciimmunol.adi9769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 12/22/2023] [Indexed: 01/13/2024]
Abstract
UNC93B1 is critical for trafficking and function of nucleic acid-sensing Toll-like receptors (TLRs) TLR3, TLR7, TLR8, and TLR9, which are essential for antiviral immunity. Overactive TLR7 signaling induced by recognition of self-nucleic acids has been implicated in systemic lupus erythematosus (SLE). Here, we report UNC93B1 variants (E92G and R336L) in four patients with early-onset SLE. Patient cells or mouse macrophages carrying the UNC93B1 variants produced high amounts of TNF-α and IL-6 and upon stimulation with TLR7/TLR8 agonist, but not with TLR3 or TLR9 agonists. E92G causes UNC93B1 protein instability and reduced interaction with TLR7, leading to selective TLR7 hyperactivation with constitutive type I IFN signaling. Thus, UNC93B1 regulates TLR subtype-specific mechanisms of ligand recognition. Our findings establish a pivotal role for UNC93B1 in TLR7-dependent autoimmunity and highlight the therapeutic potential of targeting TLR7 in SLE.
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Affiliation(s)
- Christine Wolf
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany
| | - Ee Lyn Lim
- Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Mohammad Mokhtari
- Gene Center, Systems Immunology, Ludwig-Maximilians-Universität Munich, Munich 81377, Germany
| | - Barbara Kind
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany
| | - Alexandru Odainic
- Institute of Innate Immunity, University of Bonn, Bonn 53127, Germany
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection & Immunity, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Eusebia Lara-Villacanas
- Department of Pediatrics, Klinikum Dortmund, University Witten/Herdecke, Dortmund 44145, Germany
| | - Sarah Koss
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany
| | - Simon Mages
- Gene Center, Systems Immunology, Ludwig-Maximilians-Universität Munich, Munich 81377, Germany
| | - Katharina Menzel
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany
| | - Kerstin Engel
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany
| | - Gregor Dückers
- Department of Pediatrics, Helios Klinik Krefeld, Krefeld 47805, Germany
| | - Benedikt Bernbeck
- Department of Pediatrics, Klinikum Dortmund, University Witten/Herdecke, Dortmund 44145, Germany
| | - Dominik T Schneider
- Department of Pediatrics, Klinikum Dortmund, University Witten/Herdecke, Dortmund 44145, Germany
| | | | - Tim Niehues
- Department of Pediatrics, Helios Klinik Krefeld, Krefeld 47805, Germany
| | - Carl Christoph Goetzke
- Department of Pediatric Respiratory Medicine, Immunology and Critical Care Medicine, Charité-Universitätsmedizin Berlin, Berlin 10117, Germany
- Deutsches Rheuma-Forschungszentrum (DRFZ), an institute of the Leibniz Association, Berlin 10117, Germany
- Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Berlin 10178, Germany
| | - Pawel Durek
- Deutsches Rheuma-Forschungszentrum (DRFZ), an institute of the Leibniz Association, Berlin 10117, Germany
| | - Kirsten Minden
- Department of Pediatric Respiratory Medicine, Immunology and Critical Care Medicine, Charité-Universitätsmedizin Berlin, Berlin 10117, Germany
- Deutsches Rheuma-Forschungszentrum (DRFZ), an institute of the Leibniz Association, Berlin 10117, Germany
| | - Thomas Dörner
- Deutsches Rheuma-Forschungszentrum (DRFZ), an institute of the Leibniz Association, Berlin 10117, Germany
- Department of Medicine, Rheumatology and Clinical Immunology, Charite-Universitätsmedizin Berlin, Berlin 10117, Germany
| | - Anna Stittrich
- Labor Berlin Charité-Vivantes GmbH, Department of Human Genetics, Berlin 13353, Germany
| | - Franziska Szelinski
- Deutsches Rheuma-Forschungszentrum (DRFZ), an institute of the Leibniz Association, Berlin 10117, Germany
- Department of Medicine, Rheumatology and Clinical Immunology, Charite-Universitätsmedizin Berlin, Berlin 10117, Germany
| | - Gabriela Maria Guerra
- Deutsches Rheuma-Forschungszentrum (DRFZ), an institute of the Leibniz Association, Berlin 10117, Germany
| | - Mona Massoud
- Deutsches Rheuma-Forschungszentrum (DRFZ), an institute of the Leibniz Association, Berlin 10117, Germany
| | - Markus Bieringer
- Department of Cardiology and Nephrology, HELIOS Klinikum Berlin-Buch, Berlin 13125, Germany
| | | | - Eduardo Beltrán
- Institute for Clinical Neuroimmunology, BioMedizinisches Zentrum, Ludwig-Maximilians-Universität Munich, Munich 82152, Germany
| | - Tilmann Kallinich
- Department of Pediatric Respiratory Medicine, Immunology and Critical Care Medicine, Charité-Universitätsmedizin Berlin, Berlin 10117, Germany
- Deutsches Rheuma-Forschungszentrum (DRFZ), an institute of the Leibniz Association, Berlin 10117, Germany
- Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Berlin 10178, Germany
| | - Mir-Farzin Mashreghi
- Deutsches Rheuma-Forschungszentrum (DRFZ), an institute of the Leibniz Association, Berlin 10117, Germany
| | - Susanne V Schmidt
- Institute of Innate Immunity, University of Bonn, Bonn 53127, Germany
| | - Eicke Latz
- Institute of Innate Immunity, University of Bonn, Bonn 53127, Germany
- German Center for Neurodegenerative Diseases (DZNE), Bonn 53175, Germany
| | - Johanna Klughammer
- Gene Center, Systems Immunology, Ludwig-Maximilians-Universität Munich, Munich 81377, Germany
| | - Olivia Majer
- Max Planck Institute for Infection Biology, Berlin 10117, Germany
| | - Min Ae Lee-Kirsch
- Department of Pediatrics, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany
- University Center for Rare Diseases, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden 01307, Germany
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3
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Tanaka A, Maeda S, Nomura T, Llamas-Covarrubias MA, Tanaka S, Jin L, Lim EL, Morikawa H, Kitagawa Y, Akizuki S, Ito Y, Fujimori C, Hirota K, Murase T, Hashimoto M, Higo J, Zamoyska R, Ueda R, Standley DM, Sakaguchi N, Sakaguchi S. Construction of a T cell receptor signaling range for spontaneous development of autoimmune disease. J Exp Med 2023; 220:213728. [PMID: 36454183 PMCID: PMC9718937 DOI: 10.1084/jem.20220386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 10/06/2022] [Accepted: 11/14/2022] [Indexed: 12/02/2022] Open
Abstract
Thymic selection and peripheral activation of conventional T (Tconv) and regulatory T (Treg) cells depend on TCR signaling, whose anomalies are causative of autoimmunity. Here, we expressed in normal mice mutated ZAP-70 molecules with different affinities for the CD3 chains, or wild type ZAP-70 at graded expression levels under tetracycline-inducible control. Both manipulations reduced TCR signaling intensity to various extents and thereby rendered those normally deleted self-reactive thymocytes to become positively selected and form a highly autoimmune TCR repertoire. The signal reduction more profoundly affected Treg development and function because their TCR signaling was further attenuated by Foxp3 that physiologically repressed the expression of TCR-proximal signaling molecules, including ZAP-70, upon TCR stimulation. Consequently, the TCR signaling intensity reduced to a critical range generated pathogenic autoimmune Tconv cells and concurrently impaired Treg development/function, leading to spontaneous occurrence of autoimmune/inflammatory diseases, such as autoimmune arthritis and inflammatory bowel disease. These results provide a general model of how altered TCR signaling evokes autoimmune disease.
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Affiliation(s)
- Atsushi Tanaka
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan.,Laboratory of Experimental Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Japan.,Department of Frontier Research in Tumor Immunology, Center of Medical Innovation and Translational Research, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Shinji Maeda
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan.,Department of Respiratory Medicine, Allergy and Clinical Immunology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Takashi Nomura
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
| | - Mara Anais Llamas-Covarrubias
- Laboratory of Systems Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Japan.,Institute of Research in Biomedical Sciences, University Center of Health Sciences, University of Guadalajara, Guadalajara, Mexico
| | - Satoshi Tanaka
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
| | - Lin Jin
- Laboratory of Systems Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Ee Lyn Lim
- Laboratory of Experimental Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Hiromasa Morikawa
- Laboratory of Experimental Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Yohko Kitagawa
- Laboratory of Experimental Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Shuji Akizuki
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
| | - Yoshinaga Ito
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
| | - Chihiro Fujimori
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
| | - Keiji Hirota
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan.,Laboratory of Experimental Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Tosei Murase
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan.,Laboratory of Experimental Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Motomu Hashimoto
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
| | - Junichi Higo
- Institute for Protein Research, Osaka University, Suita, Japan
| | - Rose Zamoyska
- Institute for Immunology and Infection Research, The University of Edinburgh, Edinburgh, UK
| | - Ryuzo Ueda
- Department of Tumor Immunology, Aichi Medical University School of Medicine, Aichi, Japan
| | - Daron M Standley
- Laboratory of Systems Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Noriko Sakaguchi
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan.,Laboratory of Experimental Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Shimon Sakaguchi
- Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan.,Laboratory of Experimental Immunology, WPI Immunology Frontier Research Center, Osaka University, Suita, Japan
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4
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Wing JB, Lim EL, Sakaguchi S. Control of foreign Ag-specific Ab responses by Treg and Tfr. Immunol Rev 2020; 296:104-119. [PMID: 32564426 DOI: 10.1111/imr.12888] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/11/2020] [Accepted: 05/21/2020] [Indexed: 12/15/2022]
Abstract
Regulatory T cells (Tregs) expressing the transcription factor Foxp3 play a critical role in the control of immune homeostasis including the regulation of humoral immunity. Recently, it has become clear that a specialized subset of Tregs, T-follicular regulatory cells (Tfr), have a particular role in the control of T-follicular helper (Tfh) cell-driven germinal center (GC) responses. Following similar differentiation signals as received by Tfh, Tfr gain expression of characteristic chemokine receptors and transcription factors such as CXCR5 and BCL6 allowing them to travel to the B-cell follicle and deliver in situ suppression. It seems clear that Tfr are critical for the prevention of autoimmune antibody induction. However, their role in the control of foreign antigen-specific antibody responses appears more complex with various reports demonstrating either increased or decreased antigen-specific antibody responses following inhibition of Tfr function. Due to their recent discovery, our understanding of Tfr formation and function still has many gaps. In this review, we discuss our current knowledge of both Tregs and Tfr in the context of humoral immunity and how these cells might be manipulated in order to better control vaccine responses.
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Affiliation(s)
- James B Wing
- Laboritory of Human Immunology (Single Cell Immunology), Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Ee Lyn Lim
- Laboratory of Experimental Immunology, Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Shimon Sakaguchi
- Laboratory of Experimental Immunology, Immunology Frontier Research Center, Osaka University, Suita, Japan.,Department of Experimental Pathology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
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5
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Lim EL, Okkenhaug K. Phosphoinositide 3-kinase δ is a regulatory T-cell target in cancer immunotherapy. Immunology 2019; 157:210-218. [PMID: 31107985 PMCID: PMC6587315 DOI: 10.1111/imm.13082] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 05/02/2019] [Accepted: 05/16/2019] [Indexed: 12/15/2022] Open
Abstract
Tumour infiltration by regulatory T (Treg) cells contributes to suppression of the anti-tumour immune response, which limits the efficacy of immune-mediated cancer therapies. The phosphoinositide 3-kinase (PI3K) pathway has key roles in mediating the function of many immune cell subsets, including Treg cells. Treg function is context-dependent and depends on input from different cell surface receptors, many of which can activate the PI3K pathway. In this review, we explore how PI3Kδ contributes to signalling through several major immune cell receptors, including the T-cell receptor and co-stimulatory receptors such as CD28 and ICOS, but is antagonized by the immune checkpoint receptors CTLA-4 and PD-1. Understanding how PI3Kδ inhibition affects Treg signalling events will help to inform how best to use PI3Kδ inhibitors in clinical cancer treatment.
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Affiliation(s)
- Ee Lyn Lim
- Laboratory of Experimental ImmunologyImmunology Frontier Research CentreOsaka UniversitySuitaJapan
| | - Klaus Okkenhaug
- Division of ImmunologyDepartment of PathologyUniversity of CambridgeCambridgeUK
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6
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Lim EL, Cugliandolo FM, Rosner DR, Gyori D, Roychoudhuri R, Okkenhaug K. Phosphoinositide 3-kinase δ inhibition promotes antitumor responses but antagonizes checkpoint inhibitors. JCI Insight 2018; 3:120626. [PMID: 29875319 PMCID: PMC6124416 DOI: 10.1172/jci.insight.120626] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/01/2018] [Indexed: 12/17/2022] Open
Abstract
Multiple modes of immunosuppression restrain immune function within tumors. We previously reported that phosphoinositide 3-kinase δ (PI3Kδ) inactivation in mice confers resistance to a range of tumor models by disrupting immunosuppression mediated by regulatory T cells (Tregs). The PI3Kδ inhibitor idelalisib has proven highly effective in the clinical treatment of chronic lymphocytic leukemia and the potential to extend the use of PI3Kδ inhibitors to nonhematological cancers is being evaluated. In this work, we demonstrate that the antitumor effect of PI3Kδ inactivation is primarily mediated through the disruption of Treg function, and correlates with tumor dependence on Treg immunosuppression. Compared with Treg-specific PI3Kδ deletion, systemic PI3Kδ inactivation is less effective at conferring resistance to tumors. We show that PI3Kδ deficiency impairs the maturation and reduces the capacity of CD8+ cytotoxic T lymphocytes (CTLs) to kill tumor cells in vitro, and to respond to tumor antigen-specific immunization in vivo. PI3Kδ inactivation antagonized the antitumor effects of tumor vaccines and checkpoint blockade therapies intended to boost the CD8+ T cell response. These findings provide insights into mechanisms by which PI3Kδ inhibition promotes antitumor immunity and demonstrate that the mechanism is distinct from that mediated by immune checkpoint blockade.
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Affiliation(s)
- Ee Lyn Lim
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
| | - Fiorella M. Cugliandolo
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
| | - Dalya R. Rosner
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
| | - David Gyori
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
| | - Rahul Roychoudhuri
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
| | - Klaus Okkenhaug
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, United Kingdom
- Division of Immunology, Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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7
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Gyori D, Lim EL, Grant FM, Spensberger D, Roychoudhuri R, Shuttleworth SJ, Okkenhaug K, Stephens LR, Hawkins PT. Compensation between CSF1R+ macrophages and Foxp3+ Treg cells drives resistance to tumor immunotherapy. JCI Insight 2018; 3:120631. [PMID: 29875321 PMCID: PMC6124419 DOI: 10.1172/jci.insight.120631] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/01/2018] [Indexed: 12/31/2022] Open
Abstract
Redundancy and compensation provide robustness to biological systems but may contribute to therapy resistance. Both tumor-associated macrophages (TAMs) and Foxp3+ regulatory T (Treg) cells promote tumor progression by limiting antitumor immunity. Here we show that genetic ablation of CSF1 in colorectal cancer cells reduces the influx of immunosuppressive CSF1R+ TAMs within tumors. This reduction in CSF1-dependent TAMs resulted in increased CD8+ T cell attack on tumors, but its effect on tumor growth was limited by a compensatory increase in Foxp3+ Treg cells. Similarly, disruption of Treg cell activity through their experimental ablation produced moderate effects on tumor growth and was associated with elevated numbers of CSF1R+ TAMs. Importantly, codepletion of CSF1R+ TAMs and Foxp3+ Treg cells resulted in an increased influx of CD8+ T cells, augmentation of their function, and a synergistic reduction in tumor growth. Further, inhibition of Treg cell activity either through systemic pharmacological blockade of PI3Kδ, or its genetic inactivation within Foxp3+ Treg cells, sensitized previously unresponsive solid tumors to CSF1R+ TAM depletion and enhanced the effect of CSF1R blockade. These findings identify CSF1R+ TAMs and PI3Kδ-driven Foxp3+ Treg cells as the dominant compensatory cellular components of the immunosuppressive tumor microenvironment, with implications for the design of combinatorial immunotherapies.
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Affiliation(s)
- David Gyori
- Signalling ISP, Babraham Institute, Babraham Research Campus, Cambridge, Cambridgeshire, United Kingdom
| | - Ee Lyn Lim
- Signalling ISP, Babraham Institute, Babraham Research Campus, Cambridge, Cambridgeshire, United Kingdom
- Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Francis M. Grant
- Signalling ISP, Babraham Institute, Babraham Research Campus, Cambridge, Cambridgeshire, United Kingdom
| | - Dominik Spensberger
- Signalling ISP, Babraham Institute, Babraham Research Campus, Cambridge, Cambridgeshire, United Kingdom
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, United Kingdom
| | - Rahul Roychoudhuri
- Signalling ISP, Babraham Institute, Babraham Research Campus, Cambridge, Cambridgeshire, United Kingdom
| | - Stephen J. Shuttleworth
- Karus Therapeutics Ltd., Genesis Building, Library Avenue, Harwell Campus, Oxfordshire, United Kingdom
| | - Klaus Okkenhaug
- Signalling ISP, Babraham Institute, Babraham Research Campus, Cambridge, Cambridgeshire, United Kingdom
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Len R. Stephens
- Signalling ISP, Babraham Institute, Babraham Research Campus, Cambridge, Cambridgeshire, United Kingdom
| | - Phillip T. Hawkins
- Signalling ISP, Babraham Institute, Babraham Research Campus, Cambridge, Cambridgeshire, United Kingdom
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8
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Ali K, Soond DR, Piñeiro R, Hagemann T, Pearce W, Lim EL, Bouabe H, Scudamore CL, Hancox T, Maecker H, Friedman L, Turner M, Okkenhaug K, Vanhaesebroeck B. Corrigendum: Inactivation of PI(3)K p110δ breaks regulatory T-cell-mediated immune tolerance to cancer. Nature 2016; 535:580. [PMID: 27049952 DOI: 10.1038/nature17641] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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9
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Jung Y, Lim EL, Kang Q, May-Smith TC, Wong NHL, Standish R, Poletti F, Sahu JK, Alam SU, Richardson DJ. Cladding pumped few-mode EDFA for mode division multiplexed transmission. Opt Express 2014; 22:29008-29013. [PMID: 25402139 DOI: 10.1364/oe.22.029008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We experimentally demonstrate a few-mode erbium doped fiber amplifier (FM-EDFA) supporting 6 spatial modes with a cladding pumped architecture. Average modal gains are measured to be >20dB between 1534nm-1565nm with a differential modal gain of ~3dB among the mode groups and noise figures of 6-7dB. The cladding pumped FM-EDFA offers a cost effective alternative to core-pumped variant as low cost, high power multimode pumps can be used, and offers performance, scalability and simplicity to FM-EDFA design.
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10
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Ali K, Soond DR, Pineiro R, Hagemann T, Pearce W, Lim EL, Bouabe H, Scudamore CL, Hancox T, Maecker H, Friedman L, Turner M, Okkenhaug K, Vanhaesebroeck B. Inactivation of PI(3)K p110δ breaks regulatory T-cell-mediated immune tolerance to cancer. Nature 2014; 510:407-411. [PMID: 24919154 PMCID: PMC4501086 DOI: 10.1038/nature13444] [Citation(s) in RCA: 388] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 05/07/2014] [Indexed: 02/07/2023]
Abstract
Inhibitors against the p110δ isoform of phosphoinositide-3-OH kinase (PI(3)K) have shown remarkable therapeutic efficacy in some human leukaemias. As p110δ is primarily expressed in leukocytes, drugs against p110δ have not been considered for the treatment of solid tumours. Here we report that p110δ inactivation in mice protects against a broad range of cancers, including non-haematological solid tumours. We demonstrate that p110δ inactivation in regulatory T cells unleashes CD8(+) cytotoxic T cells and induces tumour regression. Thus, p110δ inhibitors can break tumour-induced immune tolerance and should be considered for wider use in oncology.
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Affiliation(s)
- Khaled Ali
- UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street London WC1E 6DD, UK
| | - Dalya R Soond
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Roberto Pineiro
- UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street London WC1E 6DD, UK
| | - Thorsten Hagemann
- Centre for Cancer and Inflammation, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London EC1M 6BQ, UK
| | - Wayne Pearce
- UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street London WC1E 6DD, UK
| | - Ee Lyn Lim
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Hicham Bouabe
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Cheryl L Scudamore
- Department of Pathology and Infectious Diseases, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK
| | - Timothy Hancox
- Piramed Pharma, 957 Buckingham Avenue, Slough, Berkshire, SL1 4NL, UK
| | - Heather Maecker
- Cancer Signaling and Translational Oncology, Genentech Inc, 1 DNA Way, South San Francisco, CA 94080-4990, USA
| | - Lori Friedman
- Cancer Signaling and Translational Oncology, Genentech Inc, 1 DNA Way, South San Francisco, CA 94080-4990, USA
| | - Martin Turner
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Klaus Okkenhaug
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, UK
| | - Bart Vanhaesebroeck
- UCL Cancer Institute, Paul O'Gorman Building, University College London, 72 Huntley Street London WC1E 6DD, UK
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11
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Abstract
AIMS Following publication of the Counterpoint Study (on the reversibility of Type 2 diabetes using a very low energy diet), the extent of public interest prompted the authors to make available, on a website, general information about reversing diabetes. Shortly thereafter, individuals began to feed back their personal experiences of attempting to reverse their diabetes. We have collated this information on the effects of energy restriction in motivated individuals with Type 2 diabetes that has been achieved outside a research setting. METHODS Emails, letters and telephone communications received between July 2011 and September 2012 were evaluated (n = 77: 66 men, 11 women). Median diabetes duration was 5.5 years (3 months-28 years). Reversal of diabetes was defined as achieving fasting capillary blood glucose < 6.1 mmol/l and/or, if available, HbA1c less than 43 mmol/mol (6.1%) off treatment. RESULTS Self-reported weight fell from 96.7 ± 17.5 kg at baseline to 81.9 ± 14.8 kg after weight loss (P < 0.001). Self-reported fasting blood glucose levels fell from 8.3 mmol/l (5.9-33.0) to 5.5 mmol/l (4.0-10.0) after the weight loss period (P < 0.001). Diabetes reversal was considered to have occurred in 61% of the population. Reversal of diabetes was observed in 80, 63 and 53% of those with > 20, 10-20 and < 10 kg weight loss, respectively. There was a significant correlation between degree of weight loss and reported fasting glucose levels (Rs -0.38, P = 0.006). Reversal rates according to diabetes duration were: short (< 4 years) = 73%, medium (4-8 years) = 56% and long (> 8 years) = 43%. CONCLUSION These data demonstrate that intentional weight loss achieved at home by health-motivated individuals can reverse Type 2 diabetes. Diabetes reversal should be a goal in the management of Type 2 diabetes.
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Affiliation(s)
- S Steven
- Magnetic Resonance Centre, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK.
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12
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Li MJ, Wang P, Liu X, Lim EL, Wang Z, Yeager M, Wong MP, Sham PC, Chanock SJ, Wang J. GWASdb: a database for human genetic variants identified by genome-wide association studies. Nucleic Acids Res 2011; 40:D1047-54. [PMID: 22139925 PMCID: PMC3245026 DOI: 10.1093/nar/gkr1182] [Citation(s) in RCA: 152] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Recent advances in genome-wide association studies (GWAS) have enabled us to identify thousands of genetic variants (GVs) that are associated with human diseases. As next-generation sequencing technologies become less expensive, more GVs will be discovered in the near future. Existing databases, such as NHGRI GWAS Catalog, collect GVs with only genome-wide level significance. However, many true disease susceptibility loci have relatively moderate P values and are not included in these databases. We have developed GWASdb that contains 20 times more data than the GWAS Catalog and includes less significant GVs (P < 1.0 × 10−3) manually curated from the literature. In addition, GWASdb provides comprehensive functional annotations for each GV, including genomic mapping information, regulatory effects (transcription factor binding sites, microRNA target sites and splicing sites), amino acid substitutions, evolution, gene expression and disease associations. Furthermore, GWASdb classifies these GVs according to diseases using Disease-Ontology Lite and Human Phenotype Ontology. It can conduct pathway enrichment and PPI network association analysis for these diseases. GWASdb provides an intuitive, multifunctional database for biologists and clinicians to explore GVs and their functional inferences. It is freely available at http://jjwanglab.org/gwasdb and will be updated frequently.
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Affiliation(s)
- Mulin Jun Li
- Department of Biochemistry, The University of Hong Kong, Hong Kong SAR, China
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13
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Abstract
There is increasing evidence that obesity may have pathophysiological effects that extend beyond its well-known co-morbidities; in particular its role in cancer has received considerable epidemiological support. As adipose tissue becomes strongly established as an endocrine organ, two of its most abundant and most investigated adipokines, leptin and adiponectin, are also taken beyond their traditional roles in energy homeostasis, and are implicated as mediators of the effects of obesity on cancer development. This review examines these adipokines in relation to the prostate, breast, colorectal, thyroid, renal, pancreatic, endometrial and oesophageal cancers, and how they may orchestrate the influence of obesity on the development of these malignancies.
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Affiliation(s)
- Gilberto Paz-Filho
- Department of Translational Medicine, The John Curtin School of Medical Research, The Australian National University, Garran Rd, building 131, Canberra, Australia
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14
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15
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Lim EL, Burden T, Marshall SM, Davison JM, Blott MJ, Waugh JSJ, Taylor R. Intrauterine growth rate in pregnancies complicated by type 1, type 2 and gestational diabetes. Obstet Med 2009; 2:21-5. [PMID: 27582801 DOI: 10.1258/om.2008.080057] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/08/2009] [Indexed: 11/18/2022] Open
Abstract
Fetal macrosomia is a feature of all subtypes of maternal diabetes. The intrauterine time course of development of macrosomia in type 1, type 2 and gestational diabetes (GDM) could identify the times of more rapid growth, which differ as a result of different influences in subtypes of diabetes. Higher maternal weight in type 2 and GDM may be expected to contribute to macrosomia and the blood glucose control will exert an additional influence. Information was collected prospectively on 217 pregnancies in insulin-treated women at a single centre over a six-year period. All women were managed by a single team of obstetricians and diabetologists at a Joint Obstetric Medical Clinic. The rate of increase in abdominal circumference from 28 weeks was identical in each subtype of diabetes and there were no differences between subtypes at the earliest gestation assessed. Use of customized growth centiles showed rates of macrosomia to be similar in type 1, type 2 and GDM (43.0%, 50.0% and 41.8%, respectively). The intrauterine time course to macrosomia is similar in type 1, type 2 and GDM. The relationship of macrosomia to extent of elevation of mean blood glucose control is weak, implying a low threshold for maximal effect on the rate of fetal growth.
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Affiliation(s)
- E L Lim
- The Directorates of Medicine
| | | | | | - J M Davison
- Directorates of Women's Services , Royal Victoria Infirmary , Newcastle upon Tyne , UK
| | - M J Blott
- Directorates of Women's Services , Royal Victoria Infirmary , Newcastle upon Tyne , UK
| | - J S J Waugh
- Directorates of Women's Services , Royal Victoria Infirmary , Newcastle upon Tyne , UK
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16
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Abstract
The chemical environment is one aspect of the oral environment, which could have an appreciable influence on the in vivo degradation of composite restoratives. The effects of chemical media on surface hardness of four composite restoratives (Silux [SX], Z100 [ZO], Ariston [AR] and Surefil [SF]) were investigated. The relationship between hardness and the thickness of the degradation layer was also studied. Thirty six specimens (3 x 4 x 2 mm) were made for each material. Following polymerization, the specimens were stored in artificial saliva at 37 degrees C for 24 h. The specimens were then randomly divided into six groups of six, subjected to microhardness testing (load = 500 gf, dwell time = 15 s) and stored in the following chemicals for 1 week at 37 degrees C: artificial saliva (S), distilled water (W), 0.02 N citric acid (C), 0.02 N lactic acid (L), heptane (H) and 75-25% ethanol-water solution (E). After conditioning, the specimens were again subjected to hardness testing and sectioned. Change in hardness (DH) was computed and the thickness of the degradation layer (DL) was measured using a computerized image analysis system at 600x magnification. Results of statistical analysis (ANOVA/Scheffe's [P < 0.05]) of DH based on materials were as follows: SX - E > all other mediums; ZO - W > C; and AR - S, W, E > H (> indicates significantly greater hardness change). No significant difference in DH was observed between the different chemicals for SF. The effects of chemical media on DH were found to be material dependent. A significant but weak positive correlation (Pearson's correlation [P < 0.05]) exists between change in hardness and thickness of the degradation layer.
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Affiliation(s)
- A U Yap
- Department of Restorative Dentistry, Faculty of Dentistry, National University of Singapore, Singapore.
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17
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Lim EL, Tomita AV, Thilly WG, Polz MF. Combination of competitive quantitative PCR and constant-denaturant capillary electrophoresis for high-resolution detection and enumeration of microbial cells. Appl Environ Microbiol 2001; 67:3897-903. [PMID: 11525983 PMCID: PMC93107 DOI: 10.1128/aem.67.9.3897-3903.2001] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel quantitative PCR (QPCR) approach, which combines competitive PCR with constant-denaturant capillary electrophoresis (CDCE), was adapted for enumerating microbial cells in environmental samples using the marine nanoflagellate Cafeteria roenbergensis as a model organism. Competitive PCR has been used successfully for quantification of DNA in environmental samples. However, this technique is labor intensive, and its accuracy is dependent on an internal competitor, which must possess the same amplification efficiency as the target yet can be easily discriminated from the target DNA. The use of CDCE circumvented these problems, as its high resolution permitted the use of an internal competitor which differed from the target DNA fragment by a single base and thus ensured that both sequences could be amplified with equal efficiency. The sensitivity of CDCE also enabled specific and precise detection of sequences over a broad range of concentrations. The combined competitive QPCR and CDCE approach accurately enumerated C. roenbergensis cells in eutrophic, coastal seawater at abundances ranging from approximately 10 to 10(4) cells x ml(-1). The QPCR cell estimates were confirmed by fluorescent in situ hybridization counts, but estimates of samples with <50 cells x ml(-1) by QPCR were less variable. This novel approach extends the usefulness of competitive QPCR by demonstrating its ability to reliably enumerate microorganisms at a range of environmentally relevant cell concentrations in complex aquatic samples.
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Affiliation(s)
- E L Lim
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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18
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Lim EL, Dennett MR, Caron DA. Identification of heterotrophic nanoflagellates by restriction fragment length polymorphism analysis of small subunit ribosomal DNA. J Eukaryot Microbiol 2001; 48:247-57. [PMID: 11411833 DOI: 10.1111/j.1550-7408.2001.tb00312.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thirty clones derived from twenty isolates of heterotrophic nanoflagellates originating from a variety of marine and freshwater environments were examined by restriction fragment length polymorphism analysis of small subunit ribosomal RNA genes amplified by the polymerase chain reaction (riboprinting). The data were compared with light and electron microscopical identification of the isolates. On morphological criteria, sixteen of the thirty clones belonged to the genus Paraphysomonas De Saedeleer, seven to the genus Spumella Cienkowski, four to the genus Pteridomonas Penard and three to the genus Cafeteria Fenchel and Patterson. Among these taxa, eleven ribotypes were detected by analysis with the restriction enzymes Hinf I, Hae III, Sau3A I, and Msp I. Differentiation of nanoflagellate taxa by the riboprinting method supported taxonomic classification based on morphology at the generic and species level. The utility of the method for discriminating the 'naked' flagellates and for confirming the identity of polymorphic forms among species of Paraphysomonas is demonstrated.
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Affiliation(s)
- E L Lim
- Biology Department, Temple University, Philadelphia, Pennsylvania 19122, USA.
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19
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Lim EL, Caron DA, Delong EF. Development and field application of a quantitative method for examining natural assemblages of protists with oligonucleotide probes. Appl Environ Microbiol 1996; 62:1416-23. [PMID: 8919803 PMCID: PMC167908 DOI: 10.1128/aem.62.4.1416-1423.1996] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A fluorescent in situ hybridization method that uses rRNA-targeted oligonucleotide probes for counting protists in cultures and environmental water samples is described. Filtration, hybridization, and enumeration of fixed cells with biotinylated eukaryote-specific probes and fluorescein isothiocyanate-conjugated avidin were performed directly on 0.4-microns-pore-size polycarbonate filters of Transwell cell culture inserts (Costar Corp., Cambridge, Mass.). Counts of various species of cultured protists by this probe hybridization method were not significantly different from counts obtained by the 4',6-diamidino-2-phenylindole (DAPI) and acridine orange (AO) staining methods. However, counts of total nanoplankton (TNAN) based on probe hybridizations in several field samples and in samples collected from a mesocosm experiment were frequently higher than TNAN counts obtained by staining with DAPI or AO. On the basis of these results, 25 to 70% of the TNAN determined with probes were not detectable by DAPI or AO staining. The underestimation of TNAN abundances in samples stained with DAPI or AO was attributed to the existence of small nanoplanktonic cells which could be detected with probes but not DAPI or AO and the difficulty associated with distinguishing DAPI- or AO-stained protists attached to or embedded in aggregates. We conclude from samples examined in this study that enumeration of TNAN with oligonucleotide probes provides estimates of natural TNAN abundances that are at least as high as (and in some cases higher than) counts obtained with commonly employed fluorochrome stains. The quantitative in situ hybridization method we have described here enables the direct enumeration of free-living protists in water samples with oligonucleotide probes. When combined with species-specific probes, this method will enable quantitative studies of the abundance and distribution of specific protistan taxa.
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Affiliation(s)
- E L Lim
- Biology Department, Woods Hole Oceanographic Institution, Massachusetts 02543, USA
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20
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Abstract
Nanoplanktonic protists are comprised of a diverse assemblage of species which are responsible for a variety of trophic processes in marine and freshwater ecosystems. Current methods for identifying small protists by electron microscopy do not readily permit both identification and enumeration of nanoplanktonic protists in field samples. Thus, one major goal in the application of molecular approaches in protistan ecology has been the detection and quantification of individual species in natural water samples. Sequences of small subunit ribosomal RNA (SSU rRNA) genes have proven to be useful towards achieving this goal. Comparison of sequences from clone libraries of protistan SSU rRNA genes amplified from natural assemblages of protists by the polymerase chain reaction (PCR) can be used to examine protistan diversity. Furthermore, oligonucleotide probes complementary to short sequence regions unique to species of small protists can be designed by comparative analysis of rRNA gene sequences. These probes may be used to either detect the RNA of particular species of protists in total nucleic acid extracts immobilized on membranes, or the presence of target species in water samples via in situ hybridization of whole cells. Oligonucleotide probes may also serve as primers for the selective amplification of target sequences from total population DNA by PCR. Thus, molecular sequence information is becoming increasingly useful for identifying and enumerating protists, and for studying their spatial and temporal distribution in nature. Knowledge of protistan species composition, abundance and variability in an environment can ultimately be used to relate community structure to various aspects of community function and biogeochemical activity.
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Affiliation(s)
- E L Lim
- Biology Department, Woods Hole Oceanographic Institution, Massachusetts 02543, USA
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21
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Abstract
The use of small-subunit rRNA-based oligonucleotides as probes for detecting marine nanoplanktonic protists was examined with a ciliate (an Uronema sp.), a flagellate (a Cafeteria sp.), and mixed assemblages of protists from enrichment cultures and natural seawater samples. Flow cytometry and epifluorescence microscopy analyses demonstrated that hybridizations employing fluorescein-labeled, eukaryote-specific probes intensely stained logarithmically growing protists, whereas these same protist strains in late stationary growth were barely detectable. The fluorescence intensity due to probe binding was significantly enhanced by the use of probes end labeled with biotin, which were detected by fluorescein-labeled avidin. The degree of signal amplification ranged from two- to fivefold for cultured protists in both logarithmic and stationary growth phases. Mixed assemblages of heterotrophic protists from enrichment cultures were also intensely labeled by rRNA-targeted oligonucleotide probes by the biotin-avidin detection system. Protists in late stationary growth phase and natural assemblages of protists that were otherwise undetectable when hybridized with fluorescein-labeled probes were easily visualized by this approach. In the latter samples, hybridization with multiple, biotin-labeled probes was necessary for detection of naturally occurring marine protists by epifluorescence microscopy. The signal amplification obtained with the biotin-avidin system should increase the utility of rRNA-targeted probes for identifying protists and facilitate characterization of the population structure and distribution of protists in aquatic environments.
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Affiliation(s)
- E L Lim
- Biology Department, Woods Hole Oceanographic Institution, Massachusetts 02543
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22
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Caron DA, Sanders RW, Lim EL, Marrasé C, Amaral LA, Whitney S, Aoki RB, Porters KG. Light-dependent phagotrophy in the freshwater mixotrophic chrysophyte Dinobryon cylindricum. Microb Ecol 1993; 25:93-111. [PMID: 24189708 DOI: 10.1007/bf00182132] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/1992] [Revised: 08/25/1992] [Indexed: 05/27/2023]
Abstract
The mixotrophic (bacterivorous), freshwater chrysophyte Dinobryon cylindricum was cultured under a variety of light regimes and in bacterized and axenic cultures to investigate the role of phototrophy and phagotrophy for the growth of this alga. D. cylindricum was found to be an obligate phototroph. The alga was unable to survive in continuous darkness even when cultures were supplemented with high concentrations of bacteria, and bacterivory ceased in cultures placed in the dark for a period longer than one day. Axenic growth of the alga was poor even in an optimal light regime. Live bacteria were required for sustained, vigorous growth of the alga in the light. Carbon (C), nitrogen (N), and phosphorus (P) budgets determined for the alga during growth in bacterized cultures indicated that bacterial biomass ingested by the alga may have contributed up to 25% of the organic carbon budget of the alga. Photosynthesis was the source of most ([Symbol: see text]75%) of the organic carbon of the alga. D. cylindricum populations survived but did not grow when cultured in a continuous low light intensity (30 μE m(-2) sec(-1)), or in a light intensity of 150 μE m(-2) sec(-1) for only two hours each day. Net efficiency of incorporation of bacterial C, N, and P into algal biomass under these two conditions was zero (i.e., no net algal population growth). We conclude that the primary function of bacterivorous behavior in D. cylindricum may be to provide essential growth factor(s) or major nutrients for photosynthetic growth, or to allow for the survival of individuals during periods of very low light intensity or short photoperiod.
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Affiliation(s)
- D A Caron
- Biology Department, Woods Hole Oceanographic Institution, 02543, Woods Hole, Massachusetts, USA
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23
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Lim EL. 100 percent dentists. N Y State Dent J 1992; 58:11. [PMID: 1635713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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24
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Lim EL. Vive la difference. N Y State Dent J 1989; 55:36-7. [PMID: 2771299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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