1
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Gregory CD. Hijacking homeostasis: Regulation of the tumor microenvironment by apoptosis. Immunol Rev 2023; 319:100-127. [PMID: 37553811 PMCID: PMC10952466 DOI: 10.1111/imr.13259] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 07/18/2023] [Indexed: 08/10/2023]
Abstract
Cancers are genetically driven, rogue tissues which generate dysfunctional, obdurate organs by hijacking normal, homeostatic programs. Apoptosis is an evolutionarily conserved regulated cell death program and a profoundly important homeostatic mechanism that is common (alongside tumor cell proliferation) in actively growing cancers, as well as in tumors responding to cytotoxic anti-cancer therapies. Although well known for its cell-autonomous tumor-suppressive qualities, apoptosis harbors pro-oncogenic properties which are deployed through non-cell-autonomous mechanisms and which generally remain poorly defined. Here, the roles of apoptosis in tumor biology are reviewed, with particular focus on the secreted and fragmentation products of apoptotic tumor cells and their effects on tumor-associated macrophages, key supportive cells in the aberrant homeostasis of the tumor microenvironment. Historical aspects of cell loss in tumor growth kinetics are considered and the impact (and potential impact) on tumor growth of apoptotic-cell clearance (efferocytosis) as well as released soluble and extracellular vesicle-associated factors are discussed from the perspectives of inflammation, tissue repair, and regeneration programs. An "apoptosis-centric" view is proposed in which dying tumor cells provide an important platform for intricate intercellular communication networks in growing cancers. The perspective has implications for future research and for improving cancer diagnosis and therapy.
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Affiliation(s)
- Christopher D. Gregory
- Centre for Inflammation ResearchInstitute for Regeneration and Repair, University of Edinburgh, Edinburgh BioQuarterEdinburghUK
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2
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Gregory CD, Rimmer MP. Extracellular vesicles arising from apoptosis: forms, functions, and applications. J Pathol 2023; 260:592-608. [PMID: 37294158 PMCID: PMC10952477 DOI: 10.1002/path.6138] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/04/2023] [Accepted: 05/07/2023] [Indexed: 06/10/2023]
Abstract
Extracellular vesicles (EVs) are lipid bilayer-enclosed subcellular bodies produced by most, if not all cells. Research over the last two decades has recognised the importance of EVs in intercellular communication and horizontal transfer of biological material. EVs range in diameter from tens of nanometres up to several micrometres and are able to transfer a spectrum of biologically active cargoes - from whole organelles, through macromolecules including nucleic acids and proteins, to metabolites and small molecules - from their cells of origin to recipient cells, which may consequently become physiologically or pathologically altered. Based on their modes of biogenesis, the most renowned EV classes are (1) microvesicles, (2) exosomes (both produced by healthy cells), and (3) EVs from cells undergoing regulated death by apoptosis (ApoEVs). Microvesicles bud directly from the plasma membrane, while exosomes are derived from endosomal compartments. Current knowledge of the formation and functional properties of ApoEVs lags behind that of microvesicles and exosomes, but burgeoning evidence indicates that ApoEVs carry manifold cargoes, including mitochondria, ribosomes, DNA, RNAs, and proteins, and perform diverse functions in health and disease. Here we review this evidence, which demonstrates substantial diversity in the luminal and surface membrane cargoes of ApoEVs, permitted by their very broad size range (from around 50 nm to >5 μm; the larger often termed apoptotic bodies), strongly suggests their origins through both microvesicle- and exosome-like biogenesis pathways, and indicates routes through which they interact with recipient cells. We discuss the capacity of ApoEVs to recycle cargoes and modulate inflammatory, immunological, and cell fate programmes in normal physiology and in pathological scenarios such as cancer and atherosclerosis. Finally, we provide a perspective on clinical applications of ApoEVs in diagnostics and therapeutics. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Christopher D Gregory
- Centre for Inflammation ResearchInstitute for Regeneration and Repair, University of EdinburghEdinburghUK
| | - Michael P Rimmer
- Centre for Reproductive HealthInstitute for Regeneration and Repair, University of EdinburghEdinburghUK
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Firoz A, Malik A, Ali HM, Akhter Y, Manavalan B, Kim CB. PRR-HyPred: A two-layer hybrid framework to predict pattern recognition receptors and their families by employing sequence encoded optimal features. Int J Biol Macromol 2023; 234:123622. [PMID: 36773859 DOI: 10.1016/j.ijbiomac.2023.123622] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 02/12/2023]
Abstract
Pattern recognition receptors (PRRs) recognize distinct features on the surface of pathogens or damaged cells and play key roles in the innate immune system. PRRs are divided into various families, including Toll-like receptors, retinoic acid-inducible gene-I-like receptors, nucleotide oligomerization domain-like receptors, and C-type lectin receptors. As these are implicated in host health and several diseases, their accurate identification is indispensable for their functional characterization and targeted therapeutic approaches. Here, we construct PRR-HyPred, a novel two-layer hybrid framework in which the first layer predicts whether a given sequence is PRR or non-PRR using a support vector machine, and in the second, the predicted PRR sequence is assigned to a specific family using a random forest-based classifier. Based on a 10-fold cross-validation test, PRR-HyPred achieved 83.4 % accuracy in the first layer and 95 % in the second, with Matthew's correlation coefficient values of 0.639 and 0.816, respectively. This is the first study that can simultaneously predict and classify PRRs into specific families. PRR-HyPred is available as a web portal at https://procarb.org/PRRHyPred/. We hope that it could be a valuable tool for the large-scale prediction and classification of PRRs and subsequently facilitate future studies.
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Affiliation(s)
- Ahmad Firoz
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia; Princess Dr. Najla Bint Saud Al- Saud Center for Excellence Research in Biotechnology, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Adeel Malik
- Institute of Intelligence Informatics Technology, Sangmyung University, Seoul, 03016, Republic of Korea.
| | - Hani Mohammed Ali
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia; Princess Dr. Najla Bint Saud Al- Saud Center for Excellence Research in Biotechnology, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Yusuf Akhter
- Department of Biotechnology, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Raebareli Road, Lucknow, Uttar Pradesh, 226025, India
| | - Balachandran Manavalan
- Computational Biology and Bioinformatics Laboratory, Department of Integrative Biotechnology, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, 16419, Gyeonggi-do, Republic of Korea.
| | - Chang-Bae Kim
- Department of Biotechnology, Sangmyung University, Seoul, 03016, Republic of Korea.
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Reil PM, Maghiar TT, Vîlceanu N, Pascalau A, Judea Pusta CT, Marcu F, Cavalu S, Pop O. Assessing the Role of Lipopolysaccharide (LPS) Receptor (CD14) in Septic Cardiomyopathy: The Value of Immunohistochemical Diagnostics. Diagnostics (Basel) 2022; 12:diagnostics12040781. [PMID: 35453829 PMCID: PMC9027368 DOI: 10.3390/diagnostics12040781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/28/2022] [Accepted: 03/16/2022] [Indexed: 11/16/2022] Open
Abstract
Sepsis-induced myocardial dysfunction (SIMD) is one of the major predictors of morbidity and mortality of sepsis. A high percentage of patients with SIMD develop a status similar to cardiogenic shock. A high level of bacterial lipopolysaccharide (LPS) associated with an overexpression of CD14 acts as the trigger for the release of a broad spectrum of cytokines. Our study aimed to understand the correlation between septic cardiomyopathy and CD14 immunohistochemical expression. The study included 29 patients who died of septic shock. Increased values of membranous CD14 and soluble CD14 in the heart tissue were correlated with adverse patient evolution. A high cellular expression of CD14 was noted in the study group vs. the control group (p = 0.0013). Therefore, a close positive association between the amount of LPS related to sCD14 and the cellular expression of mCD14 is probable. By extrapolation, we suggest that a large amount of sCD14 detected in the cardiac tissue will activate the mCD14–TRL4–LBP–LPS complex, which in turn will induce an inadequate immune response, resulting in heart damage proportional to the amount of LPS. CD14 could represent a valuable marker for septic cardiomyopathy; thus, apoptosis of cardiomyocytes could be foreseen by its high value.
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Affiliation(s)
| | - Teodor Traian Maghiar
- Department of Morphology Sciences, University of Oradea, 410087 Oradea, Romania; (T.T.M.); (N.V.); (C.T.J.P.); (O.P.)
| | - Narcis Vîlceanu
- Department of Morphology Sciences, University of Oradea, 410087 Oradea, Romania; (T.T.M.); (N.V.); (C.T.J.P.); (O.P.)
| | - Andrei Pascalau
- Department of Morphology Sciences, University of Oradea, 410087 Oradea, Romania; (T.T.M.); (N.V.); (C.T.J.P.); (O.P.)
- Correspondence: ; Tel.: +40-74-5778666
| | - Claudia Teodora Judea Pusta
- Department of Morphology Sciences, University of Oradea, 410087 Oradea, Romania; (T.T.M.); (N.V.); (C.T.J.P.); (O.P.)
| | - Florin Marcu
- Department of Psycho-Neuro-Sciences and Recovery, University of Oradea, 410087 Oradea, Romania;
| | - Simona Cavalu
- Faculty of Medicine and Pharmacy, University of Oradea, 410087 Oradea, Romania;
| | - Ovidiu Pop
- Department of Morphology Sciences, University of Oradea, 410087 Oradea, Romania; (T.T.M.); (N.V.); (C.T.J.P.); (O.P.)
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Le Guernic A, Geffard A, Rioult D, Bigot-Clivot A, Leprêtre M, Palos Ladeiro M. Cellular and molecular complementary immune stress markers for the model species Dreissena polymorpha. FISH & SHELLFISH IMMUNOLOGY 2020; 107:452-462. [PMID: 33197585 DOI: 10.1016/j.fsi.2020.10.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/25/2020] [Accepted: 10/27/2020] [Indexed: 06/11/2023]
Abstract
This study aimed to combine cellular and molecular analyses for better detail the effects of various stresses on a sentinel species of freshwater invertebrate. For this purpose, the hemocytes of the zebra mussel, Dreissena polymorpha, were exposed to different stresses at two different intensities, high or low: chemical (cadmium and ionomycin), physical (ultraviolet B), or biological ones (Cryptosporidium parvum and Toxoplasma gondii). After exposure, flow cytometry and droplet digital PCR analyses were performed on the same pools of hemocytes. Several responses related to necrosis, apoptosis, phagocytosis, production of nitric oxide and expression level of several genes related to the antioxidant, detoxification and immune systems were evaluated. Results showed that hemocyte integrity was compromised by both chemical and physical stress, and cellular markers of phagocytosis reacted to ionomycin and protozoa. While cadmium induced oxidative stress and necrosis, ionomycin tends to modulate the immune response of hemocytes. Although both biological stresses led to a similar immune response, C. parvum oocysts induced more effects than T. gondii, notably through the expression of effector caspases gene and an increase in hemocyte necrosis. This suggests different management of the two protozoa by the cell. This work provides new knowledge of biomarkers in the zebra mussel, at both cellular and molecular levels, and contributes to elucidate the mechanisms of action of different kinds of stress in this species.
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Affiliation(s)
- Antoine Le Guernic
- Reims Champagne-Ardenne University (URCA), Campus Moulin de La Housse, UMR-I02 SEBIO, 51687, Reims, France.
| | - Alain Geffard
- Reims Champagne-Ardenne University (URCA), Campus Moulin de La Housse, UMR-I02 SEBIO, 51687, Reims, France
| | - Damien Rioult
- Reims Champagne-Ardenne University (URCA), Campus Moulin de La Housse, UMR-I02 SEBIO, 51687, Reims, France; Plateau Technique Mobile en Cytométrie Environnementale MOBICYTE, URCA/INERIS, URCA, 51687, Reims, France
| | - Aurélie Bigot-Clivot
- Reims Champagne-Ardenne University (URCA), Campus Moulin de La Housse, UMR-I02 SEBIO, 51687, Reims, France
| | - Maxime Leprêtre
- Reims Champagne-Ardenne University (URCA), Campus Moulin de La Housse, UMR-I02 SEBIO, 51687, Reims, France
| | - Mélissa Palos Ladeiro
- Reims Champagne-Ardenne University (URCA), Campus Moulin de La Housse, UMR-I02 SEBIO, 51687, Reims, France
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6
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Sequence based prediction of pattern recognition receptors by using feature selection technique. Int J Biol Macromol 2020; 162:931-934. [DOI: 10.1016/j.ijbiomac.2020.06.234] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/23/2020] [Accepted: 06/24/2020] [Indexed: 01/04/2023]
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Abstract
During apoptosis or activation, cells can release a subcellular structure, called a membrane microvesicle (also known as microparticle) into the extracellular environment. Microvesicles bud-off as a portion of cell membrane with its associated proteins and lipids surrounding a cytosolic core that contains intracellular proteins, lipids, and nucleic acids (DNA, RNA, siRNA, microRNA, lncRNA). Biologically active molecules on the microvesicle surface and encapsulated within can act on recipient cells as a novel mode of intercellular communication. Apoptosis has long been known to be involved in the development of diseases of autoimmunity. Abnormally persistent microvesicles, particularly apoptotic microvesicles, can accelerate autoimmune responses locally in specific organs and tissues as well as systemically. In this review, we focus on studies implicating microvesicles in the pathogenesis of autoimmune diseases and their complications.
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Gregory CD, Ford CA, Voss JJLP. Microenvironmental Effects of Cell Death in Malignant Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 930:51-88. [PMID: 27558817 DOI: 10.1007/978-3-319-39406-0_3] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Although apoptosis is well recognized as a cell death program with clear anticancer roles, accumulating evidence linking apoptosis with tissue repair and regeneration indicates that its relationship with malignant disease is more complex than previously thought. Here we review how the responses of neighboring cells in the microenvironment of apoptotic tumor cells may contribute to the cell birth/cell death disequilibrium that provides the basis for cancerous tissue emergence and growth. We describe the bioactive properties of apoptotic cells and consider, in particular, how apoptosis of tumor cells can engender a range of responses including pro-oncogenic signals having proliferative, angiogenic, reparatory, and immunosuppressive features. Drawing on the parallels between wound healing, tissue regeneration and cancer, we propose the concept of the "onco-regenerative niche," a cell death-driven generic network of tissue repair and regenerative mechanisms that are hijacked in cancer. Finally, we consider how the responses to cell death in tumors can be targeted to provide more effective and long-lasting therapies.
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Affiliation(s)
- Christopher D Gregory
- MRC Centre for Inflammation Research, University of Edinburgh Queen's Medical Research Institute, Edinburgh, EH16 4TJ, UK.
| | - Catriona A Ford
- MRC Centre for Inflammation Research, University of Edinburgh Queen's Medical Research Institute, Edinburgh, EH16 4TJ, UK
| | - Jorine J L P Voss
- MRC Centre for Inflammation Research, University of Edinburgh Queen's Medical Research Institute, Edinburgh, EH16 4TJ, UK
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9
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Narvaez CJ, Matthews D, LaPorta E, Simmons KM, Beaudin S, Welsh J. The impact of vitamin D in breast cancer: genomics, pathways, metabolism. Front Physiol 2014; 5:213. [PMID: 24982636 PMCID: PMC4055997 DOI: 10.3389/fphys.2014.00213] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 05/17/2014] [Indexed: 12/31/2022] Open
Abstract
Nuclear receptors exert profound effects on mammary gland physiology and have complex roles in the etiology of breast cancer. In addition to receptors for classic steroid hormones such as estrogen and progesterone, the nuclear vitamin D receptor (VDR) interacts with its ligand 1α,25(OH)2D3 to modulate the normal mammary epithelial cell genome and subsequent phenotype. Observational studies suggest that vitamin D deficiency is common in breast cancer patients and that low vitamin D status enhances the risk for disease development or progression. Genomic profiling has characterized many 1α,25(OH)2D3 responsive targets in normal mammary cells and in breast cancers, providing insight into the molecular actions of 1α,25(OH)2D3 and the VDR in regulation of cell cycle, apoptosis, and differentiation. New areas of emphasis include regulation of tumor metabolism and innate immune responses. However, the role of VDR in individual cell types (i.e., epithelial, adipose, fibroblast, endothelial, immune) of normal and tumor tissues remains to be clarified. Furthermore, the mechanisms by which VDR integrates signaling between diverse cell types and controls soluble signals and paracrine pathways in the tissue/tumor microenvironment remain to be defined. Model systems of carcinogenesis have provided evidence that both VDR expression and 1α,25(OH)2D3 actions change with transformation but clinical data regarding vitamin D responsiveness of established tumors is limited and inconclusive. Because breast cancer is heterogeneous, analysis of VDR actions in specific molecular subtypes of the disease may help to clarify the conflicting data. The expanded use of genomic, proteomic and metabolomic approaches on a diverse array of in vitro and in vivo model systems is clearly warranted to comprehensively understand the network of vitamin D regulated pathways in the context of breast cancer.
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Affiliation(s)
- Carmen J Narvaez
- Cancer Research Center, University at Albany Rensselaer, NY, USA
| | - Donald Matthews
- Cancer Research Center, University at Albany Rensselaer, NY, USA ; Department of Biomedical Sciences, University at Albany Rensselaer, NY, USA
| | - Erika LaPorta
- Cancer Research Center, University at Albany Rensselaer, NY, USA ; Department of Biomedical Sciences, University at Albany Rensselaer, NY, USA
| | - Katrina M Simmons
- Cancer Research Center, University at Albany Rensselaer, NY, USA ; Department of Biomedical Sciences, University at Albany Rensselaer, NY, USA
| | - Sarah Beaudin
- Cancer Research Center, University at Albany Rensselaer, NY, USA ; Department of Biomedical Sciences, University at Albany Rensselaer, NY, USA
| | - JoEllen Welsh
- Cancer Research Center, University at Albany Rensselaer, NY, USA ; Department of Environmental Health Sciences, University at Albany Rensselaer, NY, USA
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10
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Snook ER, Fisher-Perkins JM, Sansing HA, Lee KM, Alvarez X, MacLean AG, Peterson KE, Lackner AA, Bunnell BA. Innate immune activation in the pathogenesis of a murine model of globoid cell leukodystrophy. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 184:382-96. [PMID: 24316110 DOI: 10.1016/j.ajpath.2013.10.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 09/19/2013] [Accepted: 10/18/2013] [Indexed: 12/13/2022]
Abstract
Globoid cell leukodystrophy is a lysosomal storage disease characterized by the loss of galactocerebrosidase. Galactocerebrosidase loss leads to the accumulation of psychosine and subsequent oligodendrocyte cell death, demyelination, macrophage recruitment, and astroglial activation and proliferation. To date, no studies have elucidated the mechanism of glial cell activation and cytokine and chemokine up-regulation and release. We explored a novel explanation for the development of the pathological changes in the early stages of globoid cell leukodystrophy associated with toll-like receptor (TLR) 2 up-regulation in the hindbrain and cerebellum as a response to dying oligodendrocytes. TLR2 up-regulation on microglia/macrophages coincided with morphological changes consistent with activation at 2 and 3 weeks of age. TLR2 up-regulation on activated microglia/macrophages resulted in astrocyte activation and marked up-regulation of cytokines/chemokines. Because oligodendrocyte cell death is an important feature of globoid cell leukodystrophy, we tested the ability of TLR2 reporter cells to respond to oligodendrocyte cell death. These reporter cells responded in vitro to medium conditioned by psychosine-treated oligodendrocytes, indicating the likelihood that oligodendrocytes release a TLR2 ligand during apoptosis. TLRs are a member of the innate immune system and initiate immune and inflammatory events; therefore, the identification of TLR2 as a potential driver in the activation of central nervous system glial activity in globoid cell leukodystrophy may provide important insight into its pathogenesis.
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Affiliation(s)
- Eric R Snook
- Division of Regenerative Medicine, Tulane National Primate Research Center, Covington, Louisiana
| | - Jeanne M Fisher-Perkins
- Division of Regenerative Medicine, Tulane National Primate Research Center, Covington, Louisiana
| | - Hope A Sansing
- Division of Comparative Pathology, Tulane National Primate Research Center, Covington, Louisiana
| | - Kim M Lee
- Division of Comparative Pathology, Tulane National Primate Research Center, Covington, Louisiana
| | - Xavier Alvarez
- Division of Comparative Pathology, Tulane National Primate Research Center, Covington, Louisiana
| | - Andrew G MacLean
- Division of Comparative Pathology, Tulane National Primate Research Center, Covington, Louisiana
| | - Karin E Peterson
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Disease, Hamilton, Montana
| | - Andrew A Lackner
- Division of Comparative Pathology, Tulane National Primate Research Center, Covington, Louisiana
| | - Bruce A Bunnell
- Division of Regenerative Medicine, Tulane National Primate Research Center, Covington, Louisiana; Department of Pharmacology, Tulane University Health Sciences Center, New Orleans, Louisiana.
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11
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Hawkins LA, Devitt A. Current understanding of the mechanisms for clearance of apoptotic cells-a fine balance. J Cell Death 2013; 6:57-68. [PMID: 25278779 PMCID: PMC4147779 DOI: 10.4137/jcd.s11037] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Apoptosis is an important cell death mechanism by which multicellular organisms remove unwanted cells. It culminates in a rapid, controlled removal of cell corpses by neighboring or recruited viable cells. Whilst many of the molecular mechanisms that mediate corpse clearance are components of the innate immune system, clearance of apoptotic cells is an anti-inflammatory process. Control of cell death is dependent on competing pro-apoptotic and anti-apoptotic signals. Evidence now suggests a similar balance of competing signals is central to the effective removal of cells, through so called 'eat me' and 'don't eat me' signals. Competing signals are also important for the controlled recruitment of phagocytes to sites of cell death. Consequently recruitment of phagocytes to and from sites of cell death can underlie the resolution or inappropriate propagation of cell death and inflammation. This article highlights our understanding of mechanisms mediating clearance of dying cells and discusses those mechanisms controlling phagocyte migration and how inappropriate control may promote important pathologies.
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Affiliation(s)
- Lois A Hawkins
- Aston Research Centre for Healthy Ageing, School of Life & Health Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Andrew Devitt
- Aston Research Centre for Healthy Ageing, School of Life & Health Sciences, Aston University, Birmingham, B4 7ET, UK
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12
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Thomas L, Bielemeier A, Lambert PA, Darveau RP, Marshall LJ, Devitt A. The N-terminus of CD14 acts to bind apoptotic cells and confers rapid-tethering capabilities on non-myeloid cells. PLoS One 2013; 8:e70691. [PMID: 23936239 PMCID: PMC3728300 DOI: 10.1371/journal.pone.0070691] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Accepted: 06/20/2013] [Indexed: 01/27/2023] Open
Abstract
Cell death and removal of cell corpses in a timely manner is a key event in both physiological and pathological situations including tissue homeostasis and the resolution of inflammation. Phagocytic clearance of cells dying by apoptosis is a complex sequential process comprising attraction, recognition, tethering, signalling and ultimately phagocytosis and degradation of cell corpses. A wide range of molecules acting as apoptotic cell-associated ligands, phagocyte-associated receptors or soluble bridging molecules have been implicated within this process. The role of myeloid cell CD14 in mediating apoptotic cell interactions with macrophages has long been known though key molecules and residues involved have not been defined. Here we sought to further dissect the function of CD14 in apoptotic cell clearance. A novel panel of THP-1 cell-derived phagocytes was employed to demonstrate that CD14 mediates effective apoptotic cell interactions with macrophages in the absence of detectable TLR4 whilst binding and responsiveness to LPS requires TLR4. Using a targeted series of CD14 point mutants expressed in non-myeloid cells we reveal CD14 residue 11 as key in the binding of apoptotic cells whilst other residues are reported as key for LPS binding. Importantly we note that expression of CD14 in non-myeloid cells confers the ability to bind rapidly to apoptotic cells. Analysis of a panel of epithelial cells reveals that a number naturally express CD14 and that this is competent to mediate apoptotic cell clearance. Taken together these data suggest that CD14 relies on residue 11 for apoptotic cell tethering and it may be an important tethering molecule on so called 'non-professional' phagocytes thus contributing to apoptotic cell clearance in a non-myeloid setting. Furthermore these data establish CD14 as a rapid-acting tethering molecule, expressed in monocytes, which may thus confer responsiveness of circulating monocytes to apoptotic cell derived material.
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Affiliation(s)
- Leanne Thomas
- School of Life & Health Sciences & Aston Research Centre for Healthy Ageing, Aston University, Birmingham, United Kingdom
| | - Anne Bielemeier
- School of Life & Health Sciences & Aston Research Centre for Healthy Ageing, Aston University, Birmingham, United Kingdom
| | - Peter A. Lambert
- School of Life & Health Sciences & Aston Research Centre for Healthy Ageing, Aston University, Birmingham, United Kingdom
| | - Richard P. Darveau
- Department of Periodontics, University of Washington, Seattle, Washington, United States of America
| | - Lindsay J. Marshall
- School of Life & Health Sciences & Aston Research Centre for Healthy Ageing, Aston University, Birmingham, United Kingdom
| | - Andrew Devitt
- School of Life & Health Sciences & Aston Research Centre for Healthy Ageing, Aston University, Birmingham, United Kingdom
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