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Pegoraro A, Grignolo M, Ruo L, Ricci L, Adinolfi E. P2X7 Variants in Pathophysiology. Int J Mol Sci 2024; 25:6673. [PMID: 38928378 PMCID: PMC11204217 DOI: 10.3390/ijms25126673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Revised: 06/11/2024] [Accepted: 06/14/2024] [Indexed: 06/28/2024] Open
Abstract
P2X7 receptor activation by extracellular adenosine triphosphate (eATP) modulates different intracellular pathways, including pro-inflammatory and tumor-promoting cascades. ATP is released by cells and necrotic tissues during stressful conditions and accumulates mainly in the inflammatory and tumoral microenvironments. As a consequence, both the P2X7 blockade and agonism have been proposed as therapeutic strategies in phlogosis and cancer. Nevertheless, most studies have been carried out on the WT fully functional receptor variant. In recent years, the discovery of P2X7 variants derived by alternative splicing mechanisms or single-nucleotide substitutions gave rise to the investigation of these new P2X7 variants' roles in different processes and diseases. Here, we provide an overview of the literature covering the function of human P2X7 splice variants and polymorphisms in diverse pathophysiological contexts, paying particular attention to their role in oncological and neuroinflammatory conditions.
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Affiliation(s)
- Anna Pegoraro
- Department of Medical Sciences, Section of Experimental Medicine, University of Ferrara, 44121 Ferrara, Italy; (M.G.); (L.R.); (L.R.)
| | | | | | | | - Elena Adinolfi
- Department of Medical Sciences, Section of Experimental Medicine, University of Ferrara, 44121 Ferrara, Italy; (M.G.); (L.R.); (L.R.)
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Cuthbertson P, Sluyter R. The P2X7 receptor is a target of p53 and regulates haematopoiesis following radiation-induced genotoxic stress. Purinergic Signal 2022; 18:399-401. [PMID: 34981331 PMCID: PMC9832200 DOI: 10.1007/s11302-021-09837-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 12/17/2021] [Indexed: 01/14/2023] Open
Affiliation(s)
- Peter Cuthbertson
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Ronald Sluyter
- Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia.
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The P2X4 purinergic receptor has emerged as a potent regulator of hematopoietic stem/progenitor cell mobilization and homing-a novel view of P2X4 and P2X7 receptor interaction in orchestrating stem cell trafficking. Leukemia 2022; 36:248-256. [PMID: 34285343 DOI: 10.1038/s41375-021-01352-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/07/2021] [Accepted: 07/12/2021] [Indexed: 02/07/2023]
Abstract
Recent evidence indicates that extracellular adenosine triphosphate (eATP), as a major mediator of purinergic signaling, plays an important role in regulating the mobilization and homing of hematopoietic stem progenitor cells (HSPCs). In our previous work we demonstrated that eATP activates the P2X7 ion channel receptor in HSPCs and that its deficiency impairs stem cell trafficking. To learn more about the role of the P2X purinergic receptor family in hematopoiesis, we phenotyped murine and human HSPCs with respect to the seven P2X receptors and observed that, these cells also highly express P2X4 receptors, which shows ~50% sequence similarity to P2X7 subtypes, but that P2X4 cells are more sensitive to eATP and signal much more rapidly. Using the selective P2X4 receptor antagonist PSB12054 as well as P2X4-KO mice, we found that the P2X4 receptor, similar to P2X7 receptor, promotes trafficking of HSPCs in that its deficiency leads to impaired chemotaxis of HSPCs in response to a stromal-derived factor 1 (SDF-1) gradient, less effective pharmacological mobilization, and defective homing and engraftment of HSPCs after transplantation into myeloablated hosts. This correlated with a decrease in SDF-1 expression in the BM microenvironment. Overall, our results confirm the proposed cooperative dependence of both receptors in response to eATP signaling. In G-CSF-induced mobilization, a lack of one receptor is not compensated by the presence of the other one, which supports their mutual dependence in regulating HSPC trafficking.
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Watson D, Adhikary SR, Cuthbertson P, Geraghty NJ, Bird KM, Elhage A, Sligar C, Sluyter R. Humanized Mouse Model to Study the P2X7 Receptor in Graft-Versus-Host Disease. Methods Mol Biol 2022; 2510:315-340. [PMID: 35776334 DOI: 10.1007/978-1-0716-2384-8_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Humanized mouse models of graft-versus-host disease (GVHD), where human immune cells are injected into immune deficient mice, are well established and provide opportunities to investigate pathways involved in GVHD development. This chapter provides an overview of human immune cell isolation, injection of these cells into immune deficient mice, monitoring of mice for signs of GVHD, and assessment of human cell engraftment using flow cytometry. Further, this chapter focuses on the P2X7 signaling pathway involved in GVHD, and describes a strategy to block the P2X7 receptor and examine the effect of this on GVHD development.
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Affiliation(s)
- Debbie Watson
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia.
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia.
| | - Sam R Adhikary
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Peter Cuthbertson
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Nicholas J Geraghty
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Katrina M Bird
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Amal Elhage
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Chloe Sligar
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
| | - Ronald Sluyter
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia
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Tung LT, Wang H, Belle JI, Petrov JC, Langlais D, Nijnik A. p53-dependent induction of P2X7 on hematopoietic stem and progenitor cells regulates hematopoietic response to genotoxic stress. Cell Death Dis 2021; 12:923. [PMID: 34625535 PMCID: PMC8501024 DOI: 10.1038/s41419-021-04202-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 08/27/2021] [Accepted: 09/16/2021] [Indexed: 02/08/2023]
Abstract
Stem and progenitor cells are the main mediators of tissue renewal and repair, both under homeostatic conditions and in response to physiological stress and injury. Hematopoietic system is responsible for the regeneration of blood and immune cells and is maintained by bone marrow-resident hematopoietic stem and progenitor cells (HSPCs). Hematopoietic system is particularly susceptible to injury in response to genotoxic stress, resulting in the risk of bone marrow failure and secondary malignancies in cancer patients undergoing radiotherapy. Here we analyze the in vivo transcriptional response of HSPCs to genotoxic stress in a mouse whole-body irradiation model and, together with p53 ChIP-Seq and studies in p53-knockout (p53KO) mice, characterize the p53-dependent and p53-independent branches of this transcriptional response. Our work demonstrates the p53-independent induction of inflammatory transcriptional signatures in HSPCs in response to genotoxic stress and identifies multiple novel p53-target genes induced in HSPCs in response to whole-body irradiation. In particular, we establish the direct p53-mediated induction of P2X7 expression on HSCs and HSPCs in response to genotoxic stress. We further demonstrate the role of P2X7 in hematopoietic response to acute genotoxic stress, with P2X7 deficiency significantly extending mouse survival in irradiation-induced hematopoietic failure. We also demonstrate the role of P2X7 in the context of long-term HSC regenerative fitness following sublethal irradiation. Overall our studies provide important insights into the mechanisms of HSC response to genotoxic stress and further suggest P2X7 as a target for pharmacological modulation of HSC fitness and hematopoietic response to genotoxic injury.
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Affiliation(s)
- Lin Tze Tung
- Department of Physiology, McGill University, Montreal, QC, Canada
- McGill University Research Centre on Complex Traits, McGill University, Montreal, QC, Canada
| | - HanChen Wang
- Department of Physiology, McGill University, Montreal, QC, Canada
- McGill University Research Centre on Complex Traits, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Jad I Belle
- Department of Physiology, McGill University, Montreal, QC, Canada
- McGill University Research Centre on Complex Traits, McGill University, Montreal, QC, Canada
| | - Jessica C Petrov
- Department of Physiology, McGill University, Montreal, QC, Canada
- McGill University Research Centre on Complex Traits, McGill University, Montreal, QC, Canada
| | - David Langlais
- McGill University Research Centre on Complex Traits, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
- McGill University Genome Centre, McGill University, Montreal, QC, Canada
- Department of Microbiology and Immunology, McGill University, Montreal, QC, Canada
| | - Anastasia Nijnik
- Department of Physiology, McGill University, Montreal, QC, Canada.
- McGill University Research Centre on Complex Traits, McGill University, Montreal, QC, Canada.
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Cuthbertson P, Geraghty NJ, Adhikary SR, Bird KM, Fuller SJ, Watson D, Sluyter R. Purinergic Signalling in Allogeneic Haematopoietic Stem Cell Transplantation and Graft-versus-Host Disease. Int J Mol Sci 2021; 22:8343. [PMID: 34361109 PMCID: PMC8348324 DOI: 10.3390/ijms22158343] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 02/08/2023] Open
Abstract
Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is a curative therapy for blood cancers and other haematological disorders. However, allo-HSCT leads to graft-versus-host disease (GVHD), a severe and often lethal immunological response, in the majority of transplant recipients. Current therapies for GVHD are limited and often reduce the effectiveness of allo-HSCT. Therefore, pro- and anti-inflammatory factors contributing to disease need to be explored in order to identify new treatment targets. Purinergic signalling plays important roles in haematopoiesis, inflammation and immunity, and recent evidence suggests that it can also affect haematopoietic stem cell transplantation and GVHD development. This review provides a detailed assessment of the emerging roles of purinergic receptors, most notably P2X7, P2Y2 and A2A receptors, and ectoenzymes, CD39 and CD73, in GVHD.
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Affiliation(s)
- Peter Cuthbertson
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (P.C.); (N.J.G.); (S.R.A.); (K.M.B.)
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Nicholas J. Geraghty
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (P.C.); (N.J.G.); (S.R.A.); (K.M.B.)
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Sam R. Adhikary
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (P.C.); (N.J.G.); (S.R.A.); (K.M.B.)
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Katrina M. Bird
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (P.C.); (N.J.G.); (S.R.A.); (K.M.B.)
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Stephen J. Fuller
- Sydney Medical School Nepean, University of Sydney, Nepean Hospital, Penrith, NSW 2747, Australia;
| | - Debbie Watson
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (P.C.); (N.J.G.); (S.R.A.); (K.M.B.)
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Ronald Sluyter
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (P.C.); (N.J.G.); (S.R.A.); (K.M.B.)
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
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De Marchi E, Pegoraro A, Adinolfi E. P2X7 Receptor in Hematological Malignancies. Front Cell Dev Biol 2021; 9:645605. [PMID: 33763425 PMCID: PMC7982859 DOI: 10.3389/fcell.2021.645605] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/01/2021] [Indexed: 12/21/2022] Open
Abstract
The P2X7 receptor is an ion channel gated by the nucleotide ATP, known for its role in immune responses and recently emerging as a critical onco-promoting factor. Lymphocytes, myeloid cells, and their precursors were among the first cells proved to express a functional P2X7 receptor; therefore, it is not surprising that lymphoproliferative and myeloproliferative diseases, also known as hematological malignancies, were shown to be related in their insurgence and progression to P2X7 alterations. Here, we overview established and recent literature relating P2X7 with the biological mechanisms underlying leukemias, lymphomas, and multiple myeloma development. Particular attention is paid to studies published in the very recent past correlating P2X7 with ATP concentration in the leukemic microenvironment and P2X7 overexpression to acute myeloid leukemia aggressiveness and response to chemotherapy. The described literature strongly suggests that P2X7 and its genetic variants could be regarded as potential new biomarkers in hematological malignancies and that both P2X7 antagonists and agonists could emerge as new therapeutic tools alone or in combination with traditional chemotherapy.
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Affiliation(s)
- Elena De Marchi
- Department of Medical Sciences, University of Ferrara, Ferrara, Italy
| | - Anna Pegoraro
- Department of Medical Sciences, University of Ferrara, Ferrara, Italy
| | - Elena Adinolfi
- Department of Medical Sciences, University of Ferrara, Ferrara, Italy
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Bujko K, Cymer M, Adamiak M, Ratajczak MZ. An Overview of Novel Unconventional Mechanisms of Hematopoietic Development and Regulators of Hematopoiesis - a Roadmap for Future Investigations. Stem Cell Rev Rep 2020; 15:785-794. [PMID: 31642043 PMCID: PMC6925068 DOI: 10.1007/s12015-019-09920-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hematopoietic stem cells (HSCs) are the best-characterized stem cells in adult tissues. Nevertheless, as of today, many open questions remain. First, what is the phenotype of the most primitive "pre-HSC" able to undergo asymmetric divisions during ex vivo expansion that gives rise to HSC for all hemato-lymphopoietic lineages. Next, most routine in vitro assays designed to study HSC specification into hematopoietic progenitor cells (HPCs) for major hematopoietic lineages are based on a limited number of peptide-based growth factors and cytokines, neglecting the involvement of several other regulators that are endowed with hematopoietic activity. Examples include many hormones, such as pituitary gonadotropins, gonadal sex hormones, IGF-1, and thyroid hormones, as well as bioactive phosphosphingolipids and extracellular nucleotides (EXNs). Moreover, in addition to regulation by stromal-derived factor 1 (SDF-1), trafficking of these cells during mobilization or homing after transplantation is also regulated by bioactive phosphosphingolipids, EXNs, and three ancient proteolytic cascades, the complement cascade (ComC), the coagulation cascade (CoA), and the fibrinolytic cascade (FibC). Finally, it has emerged that bone marrow responds by "sterile inflammation" to signals sent from damaged organs and tissues, systemic stress, strenuous exercise, gut microbiota, and the administration of certain drugs. This review will address the involvement of these unconventional regulators and present a broader picture of hematopoiesis.
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Affiliation(s)
- Kamila Bujko
- Stem Cell Institute at James Graham Brown Cancer Center, University of Louisville, 500 S. Floyd Street, Rm. 107, Louisville, KY, 40202, USA
| | - Monika Cymer
- Center for Preclinical Studies and Technology, Department of Regenerative Medicine, Medical University of Warsaw, Warsaw, Poland
| | - Mateusz Adamiak
- Center for Preclinical Studies and Technology, Department of Regenerative Medicine, Medical University of Warsaw, Warsaw, Poland
| | - Mariusz Z Ratajczak
- Stem Cell Institute at James Graham Brown Cancer Center, University of Louisville, 500 S. Floyd Street, Rm. 107, Louisville, KY, 40202, USA. .,Center for Preclinical Studies and Technology, Department of Regenerative Medicine, Medical University of Warsaw, Warsaw, Poland.
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Filippin KJ, de Souza KFS, de Araujo Júnior RT, Torquato HFV, Dias DA, Parisotto EB, Ferreira AT, Paredes-Gamero EJ. Involvement of P2 receptors in hematopoiesis and hematopoietic disorders, and as pharmacological targets. Purinergic Signal 2020; 16:1-15. [PMID: 31863258 PMCID: PMC7166233 DOI: 10.1007/s11302-019-09684-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 11/12/2019] [Indexed: 12/11/2022] Open
Abstract
Several reports have shown the presence of P2 receptors in hematopoietic stem cells (HSCs). These receptors are activated by extracellular nucleotides released from different sources. In the hematopoietic niche, the release of purines and pyrimidines in the milieu by lytic and nonlytic mechanisms has been described. The expression of P2 receptors from HSCs until maturity is still intriguing scientists. Several reports have shown the participation of P2 receptors in events associated with modulation of the immune system, but their participation in other physiological processes is under investigation. The presence of P2 receptors in HSCs and their ability to modulate this population have awakened interest in exploring the involvement of P2 receptors in hematopoiesis and their participation in hematopoietic disorders. Among the P2 receptors, the receptor P2X7 is of particular interest, because of its different roles in hematopoietic cells (e.g., infection, inflammation, cell death and survival, leukemias and lymphomas), making the P2X7 receptor a promising pharmacological target. Additionally, the role of P2Y12 receptor in platelet activation has been well-documented and is the main example of the importance of the pharmacological modulation of P2 receptor activity. In this review, we focus on the role of P2 receptors in the hematopoietic system, addressing these receptors as potential pharmacological targets.
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Affiliation(s)
- Kelly Juliana Filippin
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, 79070-900, Brazil
| | - Kamylla F S de Souza
- Departamento de Bioquímica, Universidade Federal de São Paulo, R. Três de Maio 100, São Paulo, SP, 04044-020, Brazil
| | | | - Heron Fernandes Vieira Torquato
- Departamento de Bioquímica, Universidade Federal de São Paulo, R. Três de Maio 100, São Paulo, SP, 04044-020, Brazil
- Universidade Braz Cubas, Av. Francisco Rodrigues Filho 1233, Mogi das Cruzes, SP, 08773-380, Brazil
| | - Dhébora Albuquerque Dias
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, 79070-900, Brazil
| | - Eduardo Benedetti Parisotto
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, 79070-900, Brazil
| | - Alice Teixeira Ferreira
- Departamento de Biofísica, Universidade Federal de São Paulo, R. Botucatu 862, São Paulo, SP, 04023-062, Brazil.
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição (FACFAN), Laboratório de Biologia Molecular e Culturas Celulares, Av. Costa e Silva, s/n Bairro Universitário, Campo Grande, MS, CEP: 79070-900, Brazil.
| | - Edgar J Paredes-Gamero
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS, 79070-900, Brazil.
- Departamento de Bioquímica, Universidade Federal de São Paulo, R. Três de Maio 100, São Paulo, SP, 04044-020, Brazil.
- Faculdade de Ciências Farmacêuticas, Alimentos e Nutrição (FACFAN), Laboratório de Biologia Molecular e Culturas Celulares, Av. Costa e Silva, s/n Bairro Universitário, Campo Grande, MS, CEP: 79070-900, Brazil.
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NLRP3 inflammasome couples purinergic signaling with activation of the complement cascade for the optimal release of cells from bone marrow. Leukemia 2019; 33:815-825. [PMID: 30846866 PMCID: PMC6477784 DOI: 10.1038/s41375-019-0436-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 02/17/2019] [Accepted: 02/20/2019] [Indexed: 12/14/2022]
Abstract
The mechanisms that regulate egress of hematopoietic stem/progenitor cells (HSPCs) into peripheral blood (PB) in response to stress, inflammation, tissue/organ injury, or administration of mobilization-inducing drugs are still not well understood, and because of the importance of stem cell trafficking in maintaining organism homeostasis, several complementary pathways are believed to be involved. Our group proposes that mobilization of HSPCs is mainly a result of sterile inflammation in the bone marrow (BM) microenvironment in response to pro-mobilizing stimuli and that during the initiation phase of the mobilization process BM-residing cells belonging to the innate immunity system, including granulocytes and monocytes, release danger-associated molecular pattern molecules (DAMPs, also known as alarmins), reactive oxygen species (ROS), as well as proteolytic and lipolytic enzymes. These factors together orchestrate the release of HSPCs into PB. One of the most important DAMPs released in the initiation phase of mobilization is extracellular adenosine triphosphate, a potent activator of the inflammasome. As a result of its activation, IL-1β and IL-18 as well as other pro-mobilizing mediators, including DAMPs such as high molecular group box 1 (Hmgb1) and S100 calcium-binding protein A9 (S100a9), are released. These DAMPs are important activators of the complement cascade (ComC) in the mannan-binding lectin (MBL)-dependent pathway. Specifically, Hmgb1 and S100a9 bind to MBL, which leads to activation of MBL-associated proteases, which activate the ComC and in parallel also trigger activation of the coagulation cascade (CoaC). In this review, we will highlight the novel role of the innate immunity cell-expressed NLRP3 inflammasome, which, during the initiation phase of HSPC mobilization, couples purinergic signaling with the MBL-dependent pathway of the ComC and, in parallel, the CoaC for optimal release of HSPCs. These data are important to optimize the pharmacological mobilization of HSPCs.
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