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Su J, Song Y, Zhu Z, Huang X, Fan J, Qiao J, Mao F. Cell-cell communication: new insights and clinical implications. Signal Transduct Target Ther 2024; 9:196. [PMID: 39107318 PMCID: PMC11382761 DOI: 10.1038/s41392-024-01888-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 05/09/2024] [Accepted: 06/02/2024] [Indexed: 09/11/2024] Open
Abstract
Multicellular organisms are composed of diverse cell types that must coordinate their behaviors through communication. Cell-cell communication (CCC) is essential for growth, development, differentiation, tissue and organ formation, maintenance, and physiological regulation. Cells communicate through direct contact or at a distance using ligand-receptor interactions. So cellular communication encompasses two essential processes: cell signal conduction for generation and intercellular transmission of signals, and cell signal transduction for reception and procession of signals. Deciphering intercellular communication networks is critical for understanding cell differentiation, development, and metabolism. First, we comprehensively review the historical milestones in CCC studies, followed by a detailed description of the mechanisms of signal molecule transmission and the importance of the main signaling pathways they mediate in maintaining biological functions. Then we systematically introduce a series of human diseases caused by abnormalities in cell communication and their progress in clinical applications. Finally, we summarize various methods for monitoring cell interactions, including cell imaging, proximity-based chemical labeling, mechanical force analysis, downstream analysis strategies, and single-cell technologies. These methods aim to illustrate how biological functions depend on these interactions and the complexity of their regulatory signaling pathways to regulate crucial physiological processes, including tissue homeostasis, cell development, and immune responses in diseases. In addition, this review enhances our understanding of the biological processes that occur after cell-cell binding, highlighting its application in discovering new therapeutic targets and biomarkers related to precision medicine. This collective understanding provides a foundation for developing new targeted drugs and personalized treatments.
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Affiliation(s)
- Jimeng Su
- Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing, China
- Cancer Center, Peking University Third Hospital, Beijing, China
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, China
| | - Ying Song
- Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing, China
- Cancer Center, Peking University Third Hospital, Beijing, China
| | - Zhipeng Zhu
- Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing, China
- Cancer Center, Peking University Third Hospital, Beijing, China
| | - Xinyue Huang
- Biomedical Research Institute, Shenzhen Peking University-the Hong Kong University of Science and Technology Medical Center, Shenzhen, China
| | - Jibiao Fan
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu, China
| | - Jie Qiao
- State Key Laboratory of Female Fertility Promotion, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing, China.
- National Clinical Research Center for Obstetrics and Gynecology (Peking University Third Hospital), Beijing, China.
- Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing, China.
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing, China.
| | - Fengbiao Mao
- Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing, China.
- Cancer Center, Peking University Third Hospital, Beijing, China.
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2
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Fares J, Davis ZB, Rechberger JS, Toll SA, Schwartz JD, Daniels DJ, Miller JS, Khatua S. Advances in NK cell therapy for brain tumors. NPJ Precis Oncol 2023; 7:17. [PMID: 36792722 PMCID: PMC9932101 DOI: 10.1038/s41698-023-00356-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 01/31/2023] [Indexed: 02/17/2023] Open
Abstract
Despite advances in treatment regimens that comprise surgery, chemotherapy, and radiation, outcome of many brain tumors remains dismal, more so when they recur. The proximity of brain tumors to delicate neural structures often precludes complete surgical resection. Toxicity and long-term side effects of systemic therapy remain a concern. Novel therapies are warranted. The field of NK cell-based cancer therapy has grown exponentially and currently constitutes a major area of immunotherapy innovation. This provides a new avenue for the treatment of cancerous lesions in the brain. In this review, we explore the mechanisms by which the brain tumor microenvironment suppresses NK cell mediated tumor control, and the methods being used to create NK cell products that subvert immune suppression. We discuss the pre-clinical studies evaluating NK cell-based immunotherapies that target several neuro-malignancies and highlight advances in molecular imaging of NK cells that allow monitoring of NK cell-based therapeutics. We review current and ongoing NK cell based clinical trials in neuro-oncology.
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Affiliation(s)
- Jawad Fares
- Department of Neurological Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
- Northwestern Medicine Malnati Brain Tumor Institute, Lurie Comprehensive Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Zachary B Davis
- Department of Medicine, Division of Hematology, Oncology and Transplantation, Masonic Cancer Center, University of Minnesota, Minneapolis, MN, 55454, USA
| | - Julian S Rechberger
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, 55905, USA
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN, 55905, USA
| | - Stephanie A Toll
- Department of Pediatrics, Division of Hematology/Oncology, Children's Hospital of Michigan, Detroit, MI, 48201, USA
| | - Jonathan D Schwartz
- Department of Pediatric Hematology/Oncology, Section of Neuro-Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - David J Daniels
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, 55905, USA
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic Graduate School of Biomedical Sciences, Rochester, MN, 55905, USA
| | - Jeffrey S Miller
- Department of Medicine, Division of Hematology, Oncology and Transplantation, Masonic Cancer Center, University of Minnesota, Minneapolis, MN, 55454, USA.
| | - Soumen Khatua
- Department of Pediatric Hematology/Oncology, Section of Neuro-Oncology, Mayo Clinic, Rochester, MN, 55905, USA.
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3
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Dmitriev RI, Intes X, Barroso MM. Luminescence lifetime imaging of three-dimensional biological objects. J Cell Sci 2021; 134:1-17. [PMID: 33961054 PMCID: PMC8126452 DOI: 10.1242/jcs.254763] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A major focus of current biological studies is to fill the knowledge gaps between cell, tissue and organism scales. To this end, a wide array of contemporary optical analytical tools enable multiparameter quantitative imaging of live and fixed cells, three-dimensional (3D) systems, tissues, organs and organisms in the context of their complex spatiotemporal biological and molecular features. In particular, the modalities of luminescence lifetime imaging, comprising fluorescence lifetime imaging (FLI) and phosphorescence lifetime imaging microscopy (PLIM), in synergy with Förster resonance energy transfer (FRET) assays, provide a wealth of information. On the application side, the luminescence lifetime of endogenous molecules inside cells and tissues, overexpressed fluorescent protein fusion biosensor constructs or probes delivered externally provide molecular insights at multiple scales into protein-protein interaction networks, cellular metabolism, dynamics of molecular oxygen and hypoxia, physiologically important ions, and other physical and physiological parameters. Luminescence lifetime imaging offers a unique window into the physiological and structural environment of cells and tissues, enabling a new level of functional and molecular analysis in addition to providing 3D spatially resolved and longitudinal measurements that can range from microscopic to macroscopic scale. We provide an overview of luminescence lifetime imaging and summarize key biological applications from cells and tissues to organisms.
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Affiliation(s)
- Ruslan I. Dmitriev
- Tissue Engineering and Biomaterials Group, Department of
Human Structure and Repair, Faculty of Medicine and Health Sciences,
Ghent University, Ghent 9000,
Belgium
| | - Xavier Intes
- Department of Biomedical Engineering, Center for
Modeling, Simulation and Imaging for Medicine (CeMSIM),
Rensselaer Polytechnic Institute, Troy, NY
12180-3590, USA
| | - Margarida M. Barroso
- Department of Molecular and Cellular
Physiology, Albany Medical College,
Albany, NY 12208, USA
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4
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Ulbricht C, Leben R, Rakhymzhan A, Kirchhoff F, Nitschke L, Radbruch H, Niesner RA, Hauser AE. Intravital quantification reveals dynamic calcium concentration changes across B cell differentiation stages. eLife 2021; 10:56020. [PMID: 33749591 PMCID: PMC8060033 DOI: 10.7554/elife.56020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 03/19/2021] [Indexed: 01/31/2023] Open
Abstract
Calcium is a universal second messenger present in all eukaryotic cells. The mobilization and storage of Ca2+ ions drives a number of signaling-related processes, stress-responses, or metabolic changes, all of which are relevant for the development of immune cells and their adaption to pathogens. Here, we introduce the Förster resonance energy transfer (FRET)-reporter mouse YellowCaB expressing the genetically encoded calcium indicator TN-XXL in B lymphocytes. Calcium-induced conformation change of TN-XXL results in FRET-donor quenching measurable by two-photon fluorescence lifetime imaging. For the first time, using our novel numerical analysis, we extract absolute cytoplasmic calcium concentrations in activated B cells during affinity maturation in vivo. We show that calcium in activated B cells is highly dynamic and that activation introduces a persistent calcium heterogeneity to the lineage. A characterization of absolute calcium concentrations present at any time within the cytosol is therefore of great value for the understanding of long-lived beneficial immune responses and detrimental autoimmunity.
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Affiliation(s)
- Carolin Ulbricht
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Rheumatology and Clinical Immunology, Charitéplatz 1, Berlin, Germany.,Immune Dynamics, Deutsches Rheuma-Forschungszentrum Berlin, ein Institut der Leibniz-Gemeinschaft, Berlin, Germany
| | - Ruth Leben
- Biophysical Analytics, Deutsches Rheuma-Forschungszentrum, ein Institut der Leibniz-Gemeinschaft, Berlin, Germany
| | - Asylkhan Rakhymzhan
- Biophysical Analytics, Deutsches Rheuma-Forschungszentrum, ein Institut der Leibniz-Gemeinschaft, Berlin, Germany
| | | | - Lars Nitschke
- Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Helena Radbruch
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Neuropathology, Charitéplatz 1, Berlin, Germany
| | - Raluca A Niesner
- Biophysical Analytics, Deutsches Rheuma-Forschungszentrum, ein Institut der Leibniz-Gemeinschaft, Berlin, Germany.,Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Anja E Hauser
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Department of Rheumatology and Clinical Immunology, Charitéplatz 1, Berlin, Germany.,Immune Dynamics, Deutsches Rheuma-Forschungszentrum Berlin, ein Institut der Leibniz-Gemeinschaft, Berlin, Germany
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5
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Deal J, Pleshinger DJ, Johnson SC, Leavesley SJ, Rich TC. Milestones in the development and implementation of FRET-based sensors of intracellular signals: A biological perspective of the history of FRET. Cell Signal 2020; 75:109769. [PMID: 32898611 DOI: 10.1016/j.cellsig.2020.109769] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/28/2020] [Accepted: 08/31/2020] [Indexed: 01/24/2023]
Abstract
Fӧrster resonance energy transfer (FRET) has been described for more than a century. FRET has become a mainstay for the study of protein localization in living cells and tissues. It has also become widely used in the fields that comprise cellular signaling. FRET-based probes have been developed to monitor second messenger signals, the phosphorylation state of peptides and proteins, and subsequent cellular responses. Here, we discuss the milestones that led to FRET becoming a widely used tool for the study of biological systems: the theoretical description of FRET, the insight to use FRET as a molecular ruler, and the isolation and genetic modification of green fluorescent protein (GFP). Each of these milestones were critical to the development of a myriad of FRET-based probes and reporters in common use today. FRET-probes offer a unique opportunity to interrogate second messenger signals and subsequent protein phosphorylation - and perhaps the most effective approach for study of cAMP/PKA pathways. As such, FRET probes are widely used in the study of intracellular signaling pathways. Yet, somehow, the potential of FRET-based probes to provide windows through which we can visualize complex cellular signaling systems has not been fully reached. Hence we conclude by discussing the technical challenges to be overcome if FRET-based probes are to live up to their potential for the study of complex signaling networks.
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Affiliation(s)
- J Deal
- Basic Medical Sciences Graduate Program, University of South Alabama, Mobile, AL 36688, USA; Center for Lung Biology, Departments of Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA
| | - D J Pleshinger
- Center for Lung Biology, Departments of Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA; Pharmacology and Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA
| | - S C Johnson
- Basic Medical Sciences Graduate Program, University of South Alabama, Mobile, AL 36688, USA; Pharmacology and Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA
| | - S J Leavesley
- Basic Medical Sciences Graduate Program, University of South Alabama, Mobile, AL 36688, USA; Center for Lung Biology, Departments of Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA; Pharmacology and Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA; Chemical and Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA
| | - T C Rich
- Basic Medical Sciences Graduate Program, University of South Alabama, Mobile, AL 36688, USA; Center for Lung Biology, Departments of Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA; Pharmacology and Biomolecular Engineering, University of South Alabama, Mobile, AL 36688, USA.
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6
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Mothes R, Ulbricht C, Leben R, Günther R, Hauser AE, Radbruch H, Niesner R. Teriflunomide Does Not Change Dynamics of Nadph Oxidase Activation and Neuronal Dysfunction During Neuroinflammation. Front Mol Biosci 2020; 7:62. [PMID: 32426367 PMCID: PMC7203781 DOI: 10.3389/fmolb.2020.00062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 03/24/2020] [Indexed: 12/22/2022] Open
Abstract
The multiple sclerosis therapeutic teriflunomide is known to block the de novo synthesis of pyrimidine in mitochondria by inhibiting the enzyme dihydroorotate-dehydrogenase (DHODH). The metabolic processes of oxidative phosphorylation and glycolysis are further possible downstream targets. In healthy adult mice, high levels of dihydroorotate-dehydrogenase (DHODH) activity are measured in the central nervous system (CNS), and DHODH inhibition may cause indirect effects on reactive oxygen species production and NADPH oxidase (NOX) mediated oxidative stress, known to be key aspects of the inflammatory response of the CNS. However, little is known about the effect of teriflunomide on the dynamics of NOX activation in CNS cells and subsequent alterations of neuronal function in vivo. In this study, we employed fluorescence lifetime imaging (FLIM) and phasor analysis of the endogeneous fluorescence of NAD(P)H (nicotinamide adenine dinucleotide phosphate) in the brain stem of mice to visualize the effect of teriflunomide on cellular metabolism. Furthermore, we simultaneously studied neuronal Ca2+ signals in transgenic mice with a FRET-based Troponin C Ca2+ sensor based (CerTN L15) quantified using FRET-FLIM. Hence, we directly correlated neuronal (dys-)function indicated by steadily elevated calcium levels with metabolic activity in neurons and surrounding CNS tissue. Employing our intravital co-registered imaging approach, we could not detect any significant alteration of NOX activation after incubation of the tissue with teriflunomide. Furthermore, we could not detect any changes of the inflammatory induced neuronal dysfunction due to local treatment with teriflunomide. Concerning drug safety, we can confirm that teriflunomide has no metabolic effects on neuronal function in the CNS tissue during neuroinflammation at concentrations expected in orally treated patients. The combined endogenous FLIM and calcium imaging approach developed by us and employed here uniquely meets the need to monitor cellular metabolism as a basic mechanism of tissue functions in vivo.
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Affiliation(s)
- Ronja Mothes
- Institute for Neuropathology, Charité Universitätsmedizin Berlin, Berlin, Germany.,Deutsches Rheumaforschungszentrum - Leibniz Institute, Berlin, Germany
| | - Carolin Ulbricht
- Deutsches Rheumaforschungszentrum - Leibniz Institute, Berlin, Germany.,Immunodyanmics and Intravital Microscopy, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Ruth Leben
- Deutsches Rheumaforschungszentrum - Leibniz Institute, Berlin, Germany
| | - Robert Günther
- Deutsches Rheumaforschungszentrum - Leibniz Institute, Berlin, Germany
| | - Anja E Hauser
- Deutsches Rheumaforschungszentrum - Leibniz Institute, Berlin, Germany.,Immunodyanmics and Intravital Microscopy, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Helena Radbruch
- Institute for Neuropathology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Raluca Niesner
- Deutsches Rheumaforschungszentrum - Leibniz Institute, Berlin, Germany.,Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
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7
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Wen L, Fan Z, Mikulski Z, Ley K. Imaging of the immune system - towards a subcellular and molecular understanding. J Cell Sci 2020; 133:133/5/jcs234922. [PMID: 32139598 DOI: 10.1242/jcs.234922] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Immune responses involve many types of leukocytes that traffic to the site of injury, recognize the insult and respond appropriately. Imaging of the immune system involves a set of methods and analytical tools that are used to visualize immune responses at the cellular and molecular level as they occur in real time. We will review recent and emerging technological advances in optical imaging, and their application to understanding the molecular and cellular responses of neutrophils, macrophages and lymphocytes. Optical live-cell imaging provides deep mechanistic insights at the molecular, cellular, tissue and organism levels. Live-cell imaging can capture quantitative information in real time at subcellular resolution with minimal phototoxicity and repeatedly in the same living cells or in accessible tissues of the living organism. Advanced FRET probes allow tracking signaling events in live cells. Light-sheet microscopy allows for deeper tissue penetration in optically clear samples, enriching our understanding of the higher-level organization of the immune response. Super-resolution microscopy offers insights into compartmentalized signaling at a resolution beyond the diffraction limit, approaching single-molecule resolution. This Review provides a current perspective on live-cell imaging in vitro and in vivo with a focus on the assessment of the immune system.
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Affiliation(s)
- Lai Wen
- Laboratory of Inflammation Biology, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA
| | - Zhichao Fan
- Department of Immunology, School of Medicine, UConn Health, 263 Farmington Avenue, Farmington, CT 06030, USA
| | - Zbigniew Mikulski
- Microscopy Core Facility, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA
| | - Klaus Ley
- Laboratory of Inflammation Biology, La Jolla Institute for Immunology, 9420 Athena Circle Drive, La Jolla, CA 92037, USA .,Department of Bioengineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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8
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Leben R, Köhler M, Radbruch H, Hauser AE, Niesner RA. Systematic Enzyme Mapping of Cellular Metabolism by Phasor-Analyzed Label-Free NAD(P)H Fluorescence Lifetime Imaging. Int J Mol Sci 2019; 20:ijms20225565. [PMID: 31703416 PMCID: PMC6887798 DOI: 10.3390/ijms20225565] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 11/04/2019] [Indexed: 12/15/2022] Open
Abstract
In the past years, cellular metabolism of the immune system experienced a revival, as it has become clear that it is not merely responsible for the cellular energy supply, but also impacts on many signaling pathways and, thus, on diverse cellular functions. Label-free fluorescence lifetime imaging of the ubiquitous coenzymes NADH and NADPH (NAD(P)H-FLIM) makes it possible to monitor cellular metabolism in living cells and tissues and has already been applied to study metabolic changes both under physiologic and pathologic conditions. However, due to the complex distribution of NAD(P)H-dependent enzymes in cells, whose distribution continuously changes over time, a thorough interpretation of NAD(P)H-FLIM results, in particular, resolving the contribution of various enzymes to the overall metabolic activity, remains challenging. We developed a systematic framework based on angle similarities of the phase vectors and their length to analyze NAD(P)H-FLIM data of cells and tissues based on a generally valid reference system of highly abundant NAD(P)H-dependent enzymes in cells. By using our analysis framework, we retrieve information not only about the overall metabolic activity, i.e., the fraction of free to enzyme-bound NAD(P)H, but also identified the enzymes predominantly active within the sample at a certain time point with subcellular resolution. We verified the performance of the approach by applying NAD(P)H-FLIM on a stromal-like cell line and identified a different group of enzymes that were active in the cell nuclei as compared to the cytoplasm. As the systematic phasor-based analysis framework of label-free NAD(P)H-FLIM can be applied both in vitro and in vivo, it retains the unique power to enable dynamic enzyme-based metabolic investigations, at subcellular resolution, in genuine environments.
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Affiliation(s)
- Ruth Leben
- Biophysical Analytics, Deutsches Rheuma-Forschungszentrum (DRFZ), 10117 Berlin, Germany;
- Dynamic and Functional in vivo Imaging, Freie Universität Berlin, 14163 Berlin, Germany
- Correspondence: (R.L.); (R.A.N.); Tel.: +49-30-2846-0674 (R.L.); +49-30-2846-0708 (R.A.N.)
| | - Markus Köhler
- Biophysical Analytics, Deutsches Rheuma-Forschungszentrum (DRFZ), 10117 Berlin, Germany;
- Dynamic and Functional in vivo Imaging, Freie Universität Berlin, 14163 Berlin, Germany
| | - Helena Radbruch
- Institute for Neuropathology, Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany;
| | - Anja E. Hauser
- Immune Dynamics, Deutsches Rheuma-Forschungszentrum (DRFZ), 10117 Berlin, Germany;
- Immunodynamics and Intravital Microscopy, Charité–Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Raluca A. Niesner
- Biophysical Analytics, Deutsches Rheuma-Forschungszentrum (DRFZ), 10117 Berlin, Germany;
- Dynamic and Functional in vivo Imaging, Freie Universität Berlin, 14163 Berlin, Germany
- Correspondence: (R.L.); (R.A.N.); Tel.: +49-30-2846-0674 (R.L.); +49-30-2846-0708 (R.A.N.)
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9
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Toolbox for In Vivo Imaging of Host-Parasite Interactions at Multiple Scales. Trends Parasitol 2019; 35:193-212. [PMID: 30745251 DOI: 10.1016/j.pt.2019.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 01/04/2019] [Accepted: 01/04/2019] [Indexed: 12/19/2022]
Abstract
Animal models have for long been pivotal for parasitology research. Over the last few years, techniques such as intravital, optoacoustic and magnetic resonance imaging, optical projection tomography, and selective plane illumination microscopy developed promising potential for gaining insights into host-pathogen interactions by allowing different visualization forms in vivo and ex vivo. Advances including increased resolution, penetration depth, and acquisition speed, together with more complex image analysis methods, facilitate tackling biological problems previously impossible to study and/or quantify. Here we discuss advances and challenges in the in vivo imaging toolbox, which hold promising potential for the field of parasitology.
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10
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Phasor-Based Endogenous NAD(P)H Fluorescence Lifetime Imaging Unravels Specific Enzymatic Activity of Neutrophil Granulocytes Preceding NETosis. Int J Mol Sci 2018; 19:ijms19041018. [PMID: 29596303 PMCID: PMC5979388 DOI: 10.3390/ijms19041018] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/15/2018] [Accepted: 03/17/2018] [Indexed: 12/16/2022] Open
Abstract
Time-correlated single-photon counting combined with multi-photon laser scanning microscopy has proven to be a versatile tool to perform fluorescence lifetime imaging in biological samples and, thus, shed light on cellular functions, both in vitro and in vivo. Here, by means of phasor-analyzed endogenous NAD(P)H (nicotinamide adenine dinucleotide (phosphate)) fluorescence lifetime imaging, we visualize the shift in the cellular metabolism of healthy human neutrophil granulocytes during phagocytosis of Staphylococcus aureus pHrodo™ beads. We correlate this with the process of NETosis, i.e., trapping of pathogens by DNA networks. Hence, we are able to directly show the dynamics of NADPH oxidase activation and its requirement in triggering NETosis in contrast to other pathways of cell death and to decipher the dedicated spatio-temporal sequence between NADPH oxidase activation, nuclear membrane disintegration and DNA network formation. The endogenous FLIM approach presented here uniquely meets the increasing need in the field of immunology to monitor cellular metabolism as a basic mechanism of cellular and tissue functions.
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11
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Nobis M, Warren SC, Lucas MC, Murphy KJ, Herrmann D, Timpson P. Molecular mobility and activity in an intravital imaging setting - implications for cancer progression and targeting. J Cell Sci 2018; 131:131/5/jcs206995. [PMID: 29511095 DOI: 10.1242/jcs.206995] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Molecular mobility, localisation and spatiotemporal activity are at the core of cell biological processes and deregulation of these dynamic events can underpin disease development and progression. Recent advances in intravital imaging techniques in mice are providing new avenues to study real-time molecular behaviour in intact tissues within a live organism and to gain exciting insights into the intricate regulation of live cell biology at the microscale level. The monitoring of fluorescently labelled proteins and agents can be combined with autofluorescent properties of the microenvironment to provide a comprehensive snapshot of in vivo cell biology. In this Review, we summarise recent intravital microscopy approaches in mice, in processes ranging from normal development and homeostasis to disease progression and treatment in cancer, where we emphasise the utility of intravital imaging to observe dynamic and transient events in vivo We also highlight the recent integration of advanced subcellular imaging techniques into the intravital imaging pipeline, which can provide in-depth biological information beyond the single-cell level. We conclude with an outlook of ongoing developments in intravital microscopy towards imaging in humans, as well as provide an overview of the challenges the intravital imaging community currently faces and outline potential ways for overcoming these hurdles.
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Affiliation(s)
- Max Nobis
- The Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Cancer Division, St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2010, Australia
| | - Sean C Warren
- The Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Cancer Division, St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2010, Australia
| | - Morghan C Lucas
- The Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Cancer Division, St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2010, Australia
| | - Kendelle J Murphy
- The Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Cancer Division, St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2010, Australia
| | - David Herrmann
- The Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Cancer Division, St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2010, Australia
| | - Paul Timpson
- The Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Cancer Division, St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2010, Australia
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12
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Winfree S, Hato T, Day RN. Intravital microscopy of biosensor activities and intrinsic metabolic states. Methods 2017; 128:95-104. [PMID: 28434902 PMCID: PMC5776661 DOI: 10.1016/j.ymeth.2017.04.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 04/05/2017] [Accepted: 04/18/2017] [Indexed: 01/08/2023] Open
Abstract
Intravital microscopy (IVM) is an imaging tool that is capable of detecting subcellular signaling or metabolic events as they occur in tissues in the living animal. Imaging in highly scattering biological tissues, however, is challenging because of the attenuation of signal in images acquired at increasing depths. Depth-dependent signal attenuation is the major impediment to IVM, limiting the depth from which significant data can be obtained. Therefore, making quantitative measurements by IVM requires methods that use internal calibration, or alternatively, a completely different way of evaluating the signals. Here, we describe how ratiometric imaging of genetically encoded biosensor probes can be used to make quantitative measurements of changes in the activity of cell signaling pathways. Then, we describe how fluorescence lifetime imaging can be used for label-free measurements of the metabolic states of cells within the living animal.
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Affiliation(s)
- Seth Winfree
- Department of Medicine, Division of Nephrology, Indiana University, Indianapolis, IN, USA
| | - Takashi Hato
- Department of Medicine, Division of Nephrology, Indiana University, Indianapolis, IN, USA
| | - Richard N Day
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Dr., Indianapolis, IN 46202, USA.
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13
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Radbruch H, Mothes R, Bremer D, Seifert S, Köhler R, Pohlan J, Ostendorf L, Günther R, Leben R, Stenzel W, Niesner RA, Hauser AE. Analyzing Nicotinamide Adenine Dinucleotide Phosphate Oxidase Activation in Aging and Vascular Amyloid Pathology. Front Immunol 2017; 8:844. [PMID: 28824611 PMCID: PMC5534478 DOI: 10.3389/fimmu.2017.00844] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 07/04/2017] [Indexed: 01/10/2023] Open
Abstract
In aging individuals, both protective as well as regulatory immune functions are declining, resulting in an increased susceptibility to infections as well as to autoimmunity. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2-deficiency in immune cell subsets has been shown to be associated with aging. Using intravital marker-free NAD(P)H-fluorescence lifetime imaging, we have previously identified microglia/myeloid cells and astrocytes as main cellular sources of NADPH oxidase (NOX) activity in the CNS during neuroinflammation, due to an overactivation of NOX. The overactivated NOX enzymes catalyze the massive production of the highly reactive O2−, which initiates in a chain reaction the overproduction of diverse reactive oxygen species (ROS). Age-dependent oxidative distress levels in the brain and their cellular sources are not known. Furthermore, it is unclear whether in age-dependent diseases oxidative distress is initiated by overproduction of ROS or by a decrease in antioxidant capacity, subsequently leading to neurodegeneration in the CNS. Here, we compare the activation level of NOX enzymes in the cerebral cortex of young and aged mice as well as in a model of vascular amyloid pathology. Despite the fact that a striking change in the morphology of microglia can be detected between young and aged individuals, we find comparable low-level NOX activation both in young and old mice. In contrast, aged mice with the human APPE693Q mutation, a model for cerebral amyloid angiopathy (CAA), displayed increased focal NOX overactivation in the brain cortex, especially in tissue areas around the vessels. Despite activated morphology in microglia, NOX overactivation was detected only in a small fraction of these cells, in contrast to other pathologies with overt inflammation as experimental autoimmune encephalomyelitis (EAE) or glioblastoma. Similar to these pathologies, the astrocytes majorly contribute to the NOX overactivation in the brain cortex during CAA. Together, these findings emphasize the role of other cellular sources of activated NOX than phagocytes not only during EAE but also in models of amyloid pathology. Moreover, they may strengthen the hypothesis that microglia/monocytes show a diminished potential for clearance of amyloid beta protein.
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Affiliation(s)
- Helena Radbruch
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ronja Mothes
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany.,German Rheumatism Research Center (DRFZ), A Leibniz Institute, Berlin, Germany
| | - Daniel Bremer
- German Rheumatism Research Center (DRFZ), A Leibniz Institute, Berlin, Germany
| | - Stefanie Seifert
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ralf Köhler
- Immune Dynamics, Deutsches Rheuma-Forschungszentrum (DRFZ), A Leibniz Institute, Berlin, Germany
| | - Julian Pohlan
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany.,German Rheumatism Research Center (DRFZ), A Leibniz Institute, Berlin, Germany
| | - Lennard Ostendorf
- German Rheumatism Research Center (DRFZ), A Leibniz Institute, Berlin, Germany
| | - Robert Günther
- German Rheumatism Research Center (DRFZ), A Leibniz Institute, Berlin, Germany
| | - Ruth Leben
- German Rheumatism Research Center (DRFZ), A Leibniz Institute, Berlin, Germany
| | - Werner Stenzel
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Raluca Aura Niesner
- German Rheumatism Research Center (DRFZ), A Leibniz Institute, Berlin, Germany
| | - Anja E Hauser
- German Rheumatism Research Center (DRFZ), A Leibniz Institute, Berlin, Germany.,Immune Dynamics, Charité - Universitätsmedizin Berlin, Berlin, Germany
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Conway JRW, Warren SC, Timpson P. Context-dependent intravital imaging of therapeutic response using intramolecular FRET biosensors. Methods 2017; 128:78-94. [PMID: 28435000 DOI: 10.1016/j.ymeth.2017.04.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/13/2017] [Accepted: 04/08/2017] [Indexed: 12/18/2022] Open
Abstract
Intravital microscopy represents a more physiologically relevant method for assessing therapeutic response. However, the movement into an in vivo setting brings with it several additional considerations, the primary being the context in which drug activity is assessed. Microenvironmental factors, such as hypoxia, pH, fibrosis, immune infiltration and stromal interactions have all been shown to have pronounced effects on drug activity in a more complex setting, which is often lost in simpler two- or three-dimensional assays. Here we present a practical guide for the application of intravital microscopy, looking at the available fluorescent reporters and their respective expression systems and analysis considerations. Moving in vivo, we also discuss the microscopy set up and methods available for overlaying microenvironmental context to the experimental readouts. This enables a smooth transition into applying higher fidelity intravital imaging to improve the drug discovery process.
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Affiliation(s)
- James R W Conway
- Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Cancer Division, Sydney, NSW 2010, Australia; St Vincent's Clinical School, Faculty of Medicine, University of NSW, Sydney, NSW 2010, Australia
| | - Sean C Warren
- Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Cancer Division, Sydney, NSW 2010, Australia; St Vincent's Clinical School, Faculty of Medicine, University of NSW, Sydney, NSW 2010, Australia
| | - Paul Timpson
- Garvan Institute of Medical Research and The Kinghorn Cancer Centre, Cancer Division, Sydney, NSW 2010, Australia; St Vincent's Clinical School, Faculty of Medicine, University of NSW, Sydney, NSW 2010, Australia.
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15
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Rakymzhan A, Radbruch H, Niesner RA. Quantitative Imaging of Ca 2+ by 3D-FLIM in Live Tissues. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1035:135-141. [PMID: 29080135 DOI: 10.1007/978-3-319-67358-5_9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The calcium concentration within living cells is highly dynamic and, for many cell types, a reliable indicator of the functional state of the cells-both of isolated cells, but even, more important, of cells in tissue. In order to dynamically quantify intracellular calcium levels, various genetically encoded calcium sensors have been developed-the best of which are those based on Förster resonant energy transfer (FRET). Here we present a fluorescence lifetime imaging (FLIM) method to measure FRET in such a calcium sensor (TN L15) in neurons of hippocampal slices and of the brain stem of anesthetized mice. The method gives the unique opportunity to determine absolute neuronal calcium concentrations in the living organism.
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Affiliation(s)
- Asylkhan Rakymzhan
- Deutsches Rheuma-Forschungszentrum, a Leibniz Institute, Charitéplatz 1, 10117, Berlin, Germany
| | - Helena Radbruch
- Neuropathology, Charité-Universitätsmedizin, Charitéplatz 1, 10117, Berlin, Germany
| | - Raluca A Niesner
- Deutsches Rheuma-Forschungszentrum, a Leibniz Institute, Charitéplatz 1, 10117, Berlin, Germany. .,German Rheumatism Research Center, Charitéplatz 1, 10117, Berlin, Germany.
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16
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Day RN, Tao W, Dunn KW. A simple approach for measuring FRET in fluorescent biosensors using two-photon microscopy. Nat Protoc 2016; 11:2066-80. [DOI: 10.1038/nprot.2016.121] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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17
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Maysinger D, Zhang I. Nutritional and Nanotechnological Modulators of Microglia. Front Immunol 2016; 7:270. [PMID: 27471505 PMCID: PMC4945637 DOI: 10.3389/fimmu.2016.00270] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 06/27/2016] [Indexed: 12/11/2022] Open
Abstract
Microglia are the essential responders to alimentary, pharmacological, and nanotechnological immunomodulators. These neural cells play multiple roles as surveyors, sculptors, and guardians of essential parts of complex neural circuitries. Microglia can play dual roles in the central nervous system; they can be deleterious and/or protective. The immunomodulatory effects of alimentary components, gut microbiota, and nanotechnological products have been investigated in microglia at the single-cell level and in vivo using intravital imaging approaches, and different biochemical assays. This review highlights some of the emerging questions and topics from studies involving alimentation, microbiota, nanotechnological products, and associated problems in this area of research. Some of the advantages and limitations of in vitro and in vivo models used to study the neuromodulatory effects of these factors, as well as the merits and pitfalls of intravital imaging modalities employed are presented.
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Affiliation(s)
- Dusica Maysinger
- Department of Pharmacology and Therapeutics, McGill University , Montreal, QC , Canada
| | - Issan Zhang
- Department of Pharmacology and Therapeutics, McGill University , Montreal, QC , Canada
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18
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Kawakami N. In vivo imaging in autoimmune diseases in the central nervous system. Allergol Int 2016; 65:235-42. [PMID: 26935215 DOI: 10.1016/j.alit.2016.02.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 02/02/2016] [Indexed: 11/18/2022] Open
Abstract
Intravital imaging is becoming more popular and is being used to visualize cellular motility and functions. In contrast to in vitro analysis, which resembles in vivo analysis, intravital imaging can be used to observe and analyze cells directly in vivo. In this review, I will summarize recent imaging studies of autoreactive T cell infiltration into the central nervous system (CNS) and provide technical background. During their in vivo journey, autoreactive T cells interact with many different cells. At first, autoreactive T cells interact with endothelial cells in the airways of the lung or with splenocytes, where they acquire a migratory phenotype to infiltrate into the CNS. After arriving at the CNS, they interact with endothelial cells of the leptomeningeal vessels or the choroid plexus before passing through the blood-brain barrier. CNS-infiltrating T cells become activated by recognizing endogenous autoantigens presented by local antigen-presenting cells (APCs). This activation was visualized in vivo by using protein-based sensors. One such sensor detects changes in intracellular calcium concentration as an early marker of T cell activation. Another sensor detects translocation of Nuclear factor of activated T-cells (NFAT) from cytosol to nucleus as a definitive sign of T cell activation. Importantly, intravital imaging is not just used to visualize cellular behavior. Together with precise analysis, intravital imaging deepens our knowledge of cellular functions in living organs and also provides a platform for developing therapeutic treatments.
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Affiliation(s)
- Naoto Kawakami
- Institute of Clinical Neuroimmunology, Biomedical Center and University Hospital, Ludwig-Maximilians Universitaet Muenchen, Munich, Germany; Neuroimmunology Group, Max-Planck Institute of Neurobiology, Martinsried, Germany.
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19
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Radbruch H, Bremer D, Guenther R, Cseresnyes Z, Lindquist R, Hauser AE, Niesner R. Ongoing Oxidative Stress Causes Subclinical Neuronal Dysfunction in the Recovery Phase of EAE. Front Immunol 2016; 7:92. [PMID: 27014271 DOI: 10.3389/fimmu.2016.00092] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2015] [Accepted: 02/25/2016] [Indexed: 11/13/2022] Open
Abstract
Most multiple sclerosis (MS) patients develop over time a secondary progressive disease course, characterized histologically by axonal loss and atrophy. In early phases of the disease, focal inflammatory demyelination leads to functional impairment, but the mechanism of chronic progression in MS is still under debate. Reactive oxygen species generated by invading and resident central nervous system (CNS) macrophages have been implicated in mediating demyelination and axonal damage, but demyelination and neurodegeneration proceed even in the absence of obvious immune cell infiltration, during clinical recovery in chronic MS. Here, we employ intravital NAD(P)H fluorescence lifetime imaging to detect functional NADPH oxidases (NOX1-4, DUOX1, 2) and, thus, to identify the cellular source of oxidative stress in the CNS of mice affected by experimental autoimmune encephalomyelitis (EAE) in the remission phase of the disease. This directly affects neuronal function in vivo, as monitored by cellular calcium levels using intravital FRET-FLIM, providing a possible mechanism of disease progression in MS.
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Affiliation(s)
- Helena Radbruch
- Department of Neuropathology, Charité - Universitätsmedizin Berlin , Berlin , Germany
| | - Daniel Bremer
- German Rheumatism Research Center (DRFZ) a Leibniz Institute , Berlin , Germany
| | - Robert Guenther
- German Rheumatism Research Center (DRFZ) a Leibniz Institute , Berlin , Germany
| | - Zoltan Cseresnyes
- German Rheumatism Research Center (DRFZ) a Leibniz Institute , Berlin , Germany
| | - Randall Lindquist
- German Rheumatism Research Center (DRFZ) a Leibniz Institute , Berlin , Germany
| | - Anja E Hauser
- German Rheumatism Research Center (DRFZ) a Leibniz Institute, Berlin, Germany; Immundynamics, Charité - Universiätsmedizin Berlin, Berlin, Germany
| | - Raluca Niesner
- German Rheumatism Research Center (DRFZ) a Leibniz Institute , Berlin , Germany
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20
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Tao W, Rubart M, Ryan J, Xiao X, Qiao C, Hato T, Davidson MW, Dunn KW, Day RN. A practical method for monitoring FRET-based biosensors in living animals using two-photon microscopy. Am J Physiol Cell Physiol 2015; 309:C724-35. [PMID: 26333599 DOI: 10.1152/ajpcell.00182.2015] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 08/25/2015] [Indexed: 01/07/2023]
Abstract
The commercial availability of multiphoton microscope systems has nurtured the growth of intravital microscopy as a powerful technique for evaluating cell biology in the relevant context of living animals. In parallel, new fluorescent protein (FP) biosensors have become available that enable studies of the function of a wide range of proteins in living cells. Biosensor probes that exploit Förster resonance energy transfer (FRET) are among the most sensitive indicators of an array of cellular processes. However, differences between one-photon and two-photon excitation (2PE) microscopy are such that measuring FRET by 2PE in the intravital setting remains challenging. Here, we describe an approach that simplifies the use of FRET-based biosensors in intravital 2PE microscopy. Based on a systematic comparison of many different FPs, we identified the monomeric (m) FPs mTurquoise and mVenus as particularly well suited for intravital 2PE FRET studies, enabling the ratiometric measurements from linked FRET probes using a pair of experimental images collected simultaneously. The behavior of the FPs is validated by fluorescence lifetime and sensitized emission measurements of a set of FRET standards. The approach is demonstrated using a modified version of the AKAR protein kinase A biosensor, first in cells in culture, and then in hepatocytes in the liver of living mice. The approach is compatible with the most common 2PE microscope configurations and should be applicable to a variety of different FRET probes.
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Affiliation(s)
- Wen Tao
- Department of Medicine, Division of Nephrology, Indiana University Medical Center, Indianapolis, Indiana
| | - Michael Rubart
- Riley Heart Research Center, Wells Center for Pediatric Research, and Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jennifer Ryan
- Department of Medicine, Division of Nephrology, Indiana University Medical Center, Indianapolis, Indiana
| | - Xiao Xiao
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; and
| | - Chunping Qiao
- Division of Molecular Pharmaceutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; and
| | - Takashi Hato
- Department of Medicine, Division of Nephrology, Indiana University Medical Center, Indianapolis, Indiana
| | - Michael W Davidson
- National High Magnetic Field Laboratory and Department of Biological Science, The Florida State University, Tallahassee, Florida
| | - Kenneth W Dunn
- Department of Medicine, Division of Nephrology, Indiana University Medical Center, Indianapolis, Indiana
| | - Richard N Day
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana
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