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Borg RJ, Samson AL, Au AEL, Scholzen A, Fuchsberger M, Kong YY, Freeman R, Mifsud NA, Plebanski M, Medcalf RL. Dendritic Cell-Mediated Phagocytosis but Not Immune Activation Is Enhanced by Plasmin. PLoS One 2015; 10:e0131216. [PMID: 26132730 PMCID: PMC4488505 DOI: 10.1371/journal.pone.0131216] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 05/29/2015] [Indexed: 12/31/2022] Open
Abstract
Removal of dead cells in the absence of concomitant immune stimulation is essential for tissue homeostasis. We recently identified an injury-induced protein misfolding event that orchestrates the plasmin-dependent proteolytic degradation of necrotic cells. As impaired clearance of dead cells by the innate immune system predisposes to autoimmunity, we determined whether plasmin could influence endocytosis and immune cell stimulation by dendritic cells – a critical cell that links the innate and adaptive immune systems. We find that plasmin generated on the surface of necrotic cells enhances their phagocytic removal by human monocyte-derived dendritic cells. Plasmin also promoted phagocytosis of protease-resistant microparticles by diverse mouse dendritic cell sub-types both in vitro and in vivo. Together with an increased phagocytic capacity, plasmin-treated dendritic cells maintain an immature phenotype, exhibit reduced migration to lymph nodes, increase their expression/release of the immunosuppressive cytokine TGF-β, and lose their capacity to mount an allogeneic response. Collectively, our findings support a novel role for plasmin formed on dead cells and other phagocytic targets in maintaining tissue homeostasis by increasing the phagocytic function of dendritic cells while simultaneously decreasing their immunostimulatory capacity consistent with producing an immunosuppressive state.
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Affiliation(s)
- Rachael J. Borg
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct, Melbourne, 3004, Victoria Australia
| | - Andre L. Samson
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct, Melbourne, 3004, Victoria Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, 3181, Australia
| | - Amanda E.-L. Au
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct, Melbourne, 3004, Victoria Australia
| | - Anja Scholzen
- Department of Immunology, Monash University, Alfred Medical Research and Education Precinct, Melbourne, 3004, Victoria, Australia
| | - Martina Fuchsberger
- Department of Immunology, Monash University, Alfred Medical Research and Education Precinct, Melbourne, 3004, Victoria, Australia
| | - Ying Y. Kong
- Department of Immunology, Monash University, Alfred Medical Research and Education Precinct, Melbourne, 3004, Victoria, Australia
| | - Roxann Freeman
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct, Melbourne, 3004, Victoria Australia
| | - Nicole A. Mifsud
- Department of Medicine, Monash University, Alfred Medical Research and Education Precinct, Melbourne, 3004, Victoria, Australia
- Department of Allergy, Immunology and Respiratory Medicine, Alfred Medical Research and Education Precinct, Melbourne, 3004, Victoria, Australia
| | - Magdalena Plebanski
- Department of Immunology, Monash University, Alfred Medical Research and Education Precinct, Melbourne, 3004, Victoria, Australia
| | - Robert L. Medcalf
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct, Melbourne, 3004, Victoria Australia
- * E-mail:
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Samson AL, Knaupp AS, Sashindranath M, Borg RJ, Au AEL, Cops EJ, Saunders HM, Cody SH, McLean CA, Nowell CJ, Hughes VA, Bottomley SP, Medcalf RL. Nucleocytoplasmic coagulation: an injury-induced aggregation event that disulfide crosslinks proteins and facilitates their removal by plasmin. Cell Rep 2012; 2:889-901. [PMID: 23041318 DOI: 10.1016/j.celrep.2012.08.026] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 07/27/2012] [Accepted: 08/24/2012] [Indexed: 11/18/2022] Open
Abstract
Cellular injury causes a myriad of processes that affect proteostasis. We describe nucleocytoplasmic coagulation (NCC), an intracellular disulfide-dependent protein crosslinking event occurring upon late-stage cell death that orchestrates the proteolytic removal of misfolded proteins. In vitro and in vivo models of neuronal injury show that NCC involves conversion of soluble intracellular proteins, including tubulin, into insoluble oligomers. These oligomers, also seen in human brain tissue following neurotrauma, act as a cofactor and substrate for the plasminogen-activating system. In plasminogen(-/-) mice, levels of misfolded β-tubulin were elevated and its clearance delayed following neurotrauma, demonstrating a requirement for plasminogen in the removal of NCC constituents. While additional in vivo studies will further dissect this phenomenon, our study clearly shows that NCC, a process analogous to the formation of thrombi, generates an aggregated protein scaffold that limits release of cellular components and recruits clearance mechanisms to the site of injury.
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Affiliation(s)
- Andre L Samson
- Australian Centre for Blood Diseases, AMREP, Monash University, Melbourne, Victoria 3004, Australia.
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