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Singh S, Bensalem J, Hein LK, Casey A, Mäkinen VP, Sargeant TJ. epHero - a tandem-fluorescent probe to track the fate of apoptotic cells during efferocytosis. Cell Death Discov 2024; 10:179. [PMID: 38632247 PMCID: PMC11024195 DOI: 10.1038/s41420-024-01952-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 04/01/2024] [Accepted: 04/08/2024] [Indexed: 04/19/2024] Open
Abstract
The efficient removal of apoptotic cells via efferocytosis is critical for maintaining optimal tissue function. This involves the binding and engulfment of apoptotic cells by phagocytes and the subsequent maturation of the phagosome, culminating in lysosomal fusion and cargo destruction. However, current approaches to measure efferocytosis rely on labelling apoptotic targets with fluorescent dyes, which do not sufficiently distinguish between changes to the engulfment and acidification of apoptotic material. To address this limitation, we have developed a genetically coded ratiometric probe epHero which when expressed in the cytoplasm of target cells, bypasses the need for additional labelling steps. We demonstrate that epHero is a pH-sensitive reporter for efferocytosis and can be used to simultaneously track changes to apoptotic cell uptake and acidification, both in vitro and in mice. As proof-of-principle, we modify extracellular nutrition to show how epHero can distinguish between changes to cargo engulfment and acidification. Thus, tracking efferocytosis with epHero is a simple, cost-effective improvement on conventional techniques.
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Affiliation(s)
- Sanjna Singh
- South Australian Health and Medical Research Institute, Adelaide, SA, Australia
- University of Adelaide, Adelaide, SA, Australia
| | - Julien Bensalem
- South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Leanne K Hein
- South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Aaron Casey
- South Australian Health and Medical Research Institute, Adelaide, SA, Australia
| | - Ville-Petteri Mäkinen
- Research Unit of Population Health, Faculty of Medicine, University of Oulu, Oulu, Finland
- Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Timothy J Sargeant
- South Australian Health and Medical Research Institute, Adelaide, SA, Australia.
- University of Adelaide, Adelaide, SA, Australia.
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She Y, Xu X, Yu Q, Yang X, He J, Tang XX. Elevated expression of macrophage MERTK exhibits profibrotic effects and results in defective regulation of efferocytosis function in pulmonary fibrosis. Respir Res 2023; 24:118. [PMID: 37120511 PMCID: PMC10148433 DOI: 10.1186/s12931-023-02424-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 03/08/2023] [Indexed: 05/01/2023] Open
Abstract
Increased apoptosis of alveolar epithelial cells is a prominent feature of pulmonary fibrosis. Macrophage efferocytosis, phagocytosis of apoptotic cells by macrophages, is crucial for maintaining tissue homeostasis. Expression of Mer tyrosine kinase (MERTK, an important recognition receptor in efferocytosis) in macrophages is thought to be associated with fibrosis. However, how macrophage MERTK affects pulmonary fibrosis and whether it depends on efferocytosis are not yet clear. Here, we found elevated MERTK expression in lung macrophages from IPF patients and mice with bleomycin-induced pulmonary fibrosis. In vitro experiments showed that macrophages overexpressing MERTK exhibit profibrotic effects and that macrophage efferocytosis abrogates the profibrotic effect of MERTK by downregulating MERTK, forming a negative regulatory loop. In pulmonary fibrosis, this negative regulation is defective, and MERTK mainly exhibits profibrotic effects. Our study reveals a previously unsuspected profibrotic effect of elevated macrophage MERTK in pulmonary fibrosis and defective regulation of efferocytosis function as a result of that elevation, suggesting that targeting MERTK in macrophages may help to attenuate pulmonary fibrosis.
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Affiliation(s)
- Yixin She
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, National Center for Respiratory Medicine, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Xin Xu
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, National Center for Respiratory Medicine, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Qingyang Yu
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, National Center for Respiratory Medicine, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Xiangsheng Yang
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, National Center for Respiratory Medicine, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Jianxing He
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, National Center for Respiratory Medicine, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
| | - Xiao Xiao Tang
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, National Center for Respiratory Medicine, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.
- Guangzhou Laboratory, Bio-Island, Guangzhou, China.
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Gachanja NN, Dorward DA, Rossi AG, Lucas CD. Assays of Eosinophil Apoptosis and Phagocytic Uptake. Methods Mol Biol 2021; 2241:113-132. [PMID: 33486732 DOI: 10.1007/978-1-0716-1095-4_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Eosinophil apoptosis (programmed cell death) plays an important role in several inflammatory and allergic conditions. Apoptosis triggers various mechanisms including activation of cysteine-aspartic proteases (caspases) and is characterized by morphological and biochemical changes. These include cellular condensation, nuclear fragmentation, increased mitochondrial permeability with loss of membrane potential, and exposure of phosphatidylserine on the cell membrane. A greater understanding of apoptotic mechanisms, subsequent phagocytosis (efferocytosis), and regulation of these processes is critical to understanding disease pathogenesis and development of potential novel therapeutic agents. Release of soluble factors and alterations to surface marker expression by eosinophils undergoing apoptosis aid them in signaling their presence to the immediate environment, and their subsequent recognition by phagocytic cells such as macrophages. Uptake of apoptotic cells usually suppresses inflammation by restricting proinflammatory responses and promoting anti-inflammatory and tissue repair responses. This, in turn, promotes resolution of inflammation. Defects in the apoptotic or efferocytosis mechanisms perpetuate inflammation, resulting in chronic inflammation and enhanced disease severity. This can be due to increased eosinophil life span or cell necrosis characterized by loss of cell membrane integrity and release of toxic intracellular mediators. In this chapter, we detail some of the key assays that are used to assess eosinophil apoptosis, as well as the intracellular signaling pathways involved and phagocytic clearance of these cells.
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Affiliation(s)
- Naomi N Gachanja
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - David A Dorward
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Adriano G Rossi
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK.
| | - Christopher D Lucas
- MRC Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, UK.
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Grewal T, Rentero C, Enrich C, Wahba M, Raabe CA, Rescher U. Annexin Animal Models-From Fundamental Principles to Translational Research. Int J Mol Sci 2021; 22:ijms22073439. [PMID: 33810523 PMCID: PMC8037771 DOI: 10.3390/ijms22073439] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/18/2021] [Accepted: 03/24/2021] [Indexed: 02/07/2023] Open
Abstract
Routine manipulation of the mouse genome has become a landmark in biomedical research. Traits that are only associated with advanced developmental stages can now be investigated within a living organism, and the in vivo analysis of corresponding phenotypes and functions advances the translation into the clinical setting. The annexins, a family of closely related calcium (Ca2+)- and lipid-binding proteins, are found at various intra- and extracellular locations, and interact with a broad range of membrane lipids and proteins. Their impacts on cellular functions has been extensively assessed in vitro, yet annexin-deficient mouse models generally develop normally and do not display obvious phenotypes. Only in recent years, studies examining genetically modified annexin mouse models which were exposed to stress conditions mimicking human disease often revealed striking phenotypes. This review is the first comprehensive overview of annexin-related research using animal models and their exciting future use for relevant issues in biology and experimental medicine.
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Affiliation(s)
- Thomas Grewal
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW 2006, Australia;
- Correspondence: (T.G.); (U.R.); Tel.: +61-(0)2-9351-8496 (T.G.); +49-(0)251-83-52121 (U.R.)
| | - Carles Rentero
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, 08036 Barcelona, Spain; (C.R.); (C.E.)
- Centre de Recerca Biomèdica CELLEX, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Carlos Enrich
- Departament de Biomedicina, Unitat de Biologia Cel·lular, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, 08036 Barcelona, Spain; (C.R.); (C.E.)
- Centre de Recerca Biomèdica CELLEX, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), 08036 Barcelona, Spain
| | - Mohamed Wahba
- School of Pharmacy, Faculty of Medicine and Health, University of Sydney, Sydney, NSW 2006, Australia;
| | - Carsten A. Raabe
- Research Group Regulatory Mechanisms of Inflammation, Center for Molecular Biology of Inflammation (ZMBE) and Cells in Motion Interfaculty Center (CiM), Institute of Medical Biochemistry, University of Muenster, 48149 Muenster, Germany;
| | - Ursula Rescher
- Research Group Regulatory Mechanisms of Inflammation, Center for Molecular Biology of Inflammation (ZMBE) and Cells in Motion Interfaculty Center (CiM), Institute of Medical Biochemistry, University of Muenster, 48149 Muenster, Germany;
- Correspondence: (T.G.); (U.R.); Tel.: +61-(0)2-9351-8496 (T.G.); +49-(0)251-83-52121 (U.R.)
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Ito H, Yamashita Y, Tanaka T, Takaki M, Le MN, Yoshida LM, Morimoto K. Cigarette smoke induces endoplasmic reticulum stress and suppresses efferocytosis through the activation of RhoA. Sci Rep 2020; 10:12620. [PMID: 32724133 PMCID: PMC7387437 DOI: 10.1038/s41598-020-69610-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 07/15/2020] [Indexed: 12/22/2022] Open
Abstract
Impaired efferocytosis is a key mechanism of inflammatory lung diseases, including chronic obstructive pulmonary disease and cystic fibrosis. Cigarette smoking activates RhoA and impairs efferocytosis in alveolar macrophages, but the mechanism has not been fully elucidated. We investigated the role of endoplasmic reticulum (ER) stress induced by cigarette smoking in the disruption of efferocytosis. Both tunicamycin (10 μg/ml) and thapsigargin (0.1 and 1 μM), which are ER stress inducers, suppressed efferocytosis in J774 cells, and a Rho-associated coiled-coil-forming kinase (ROCK) inhibitor (Y27632) reversed this effect. We validated the effect of tunicamycin on efferocytosis in experiments using RAW264.7 cells. Then, we investigated the role of the unfolded protein response (UPR) in efferocytosis impaired by ER stress. A PERK inhibitor (GSK2606414) restored the efferocytosis that had been impaired by TM, and an eIF2α dephosphorylation inhibitor (salubrinal) suppressed efferocytosis. Cigarette smoke extract (CSE) induced ER stress in J774 macrophages and RhoA activation in J774 cells, and the CSE-induced ROCK activity was successfully reversed by GSK2606414 and tauroursodeoxycholic acid. Finally, we confirmed that ER stress suppresses efferocytosis in murine alveolar macrophages and that GSK2606414 could rescue this process. These data suggest that cigarette smoke-induced ER stress and the UPR play crucial roles in RhoA activation and suppression of efferocytosis in the lung.
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Affiliation(s)
- Hiroyuki Ito
- Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki City, Nagasaki, 852-8523, Japan.,Department of Clinical Tropical Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Yoshiro Yamashita
- Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki City, Nagasaki, 852-8523, Japan
| | - Takeshi Tanaka
- Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki City, Nagasaki, 852-8523, Japan
| | - Masahiro Takaki
- Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki City, Nagasaki, 852-8523, Japan
| | - Minh Nhat Le
- Department of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Lay-Myint Yoshida
- Department of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Konosuke Morimoto
- Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki City, Nagasaki, 852-8523, Japan. .,Department of Clinical Tropical Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
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