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Xie Y, Han R, Li Y, Li W, Zhang S, Wu Y, Zhao Y, Liu R, Wu J, Jiang W, Chen X. P2X7 receptor antagonists modulate experimental autoimmune neuritis via regulation of NLRP3 inflammasome activation and Th17 and Th1 cell differentiation. J Neuroinflammation 2024; 21:73. [PMID: 38528529 PMCID: PMC10964508 DOI: 10.1186/s12974-024-03057-z] [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: 10/06/2023] [Accepted: 02/27/2024] [Indexed: 03/27/2024] Open
Abstract
BACKGROUND Guillain-Barré syndrome (GBS), a post-infectious, immune-mediated, acute demyelinating disease of the peripheral nerves and nerve roots, represents the most prevalent and severe acute paralyzing neuropathy. Purinergic P2X7 receptors (P2X7R) play a crucial role in central nervous system inflammation. However, little is known about their role in the immune-inflammatory response within the peripheral nervous system. METHODS Initially, we assessed the expression of purinergic P2X7R in the peripheral blood of patients with GBS using flow cytometry and qRT-PCR. Next, we explored the expression of P2 X7R in CD4+ T cells, CD8+ T cells, and macrophages within the sciatic nerves and spleens of rats using immunofluorescence labeling and flow cytometry. The P2X7R antagonist brilliant blue G (BBG) was employed to examine its therapeutic impact on rats with experimental autoimmune neuritis (EAN) induced by immunization with the P0180 - 199 peptide. We analyzed CD4+ T cell differentiation in splenic mononuclear cells using flow cytometry, assessed Th17 cell differentiation in the sciatic nerve through immunofluorescence staining, and examined the expression of pro-inflammatory cytokine mRNA using RT-PCR. Additionally, we performed protein blotting to assess the expression of P2X7R and NLRP3-related inflammatory proteins within the sciatic nerve. Lastly, we utilized flow cytometry and immunofluorescence labeling to examine the expression of NLRP3 on CD4+ T cells in rats with EAN. RESULTS P2X7R expression was elevated not only in the peripheral blood of patients with GBS but also in rats with EAN. In rats with EAN, inhibiting P2X7R with BBG alleviated neurological symptoms, reduced demyelination, decreased inflammatory cell infiltration of the peripheral nerves, and improved nerve conduction. BBG also limited the production of pro-inflammatory molecules, down-regulated the expression of P2X7R and NLRP3, and suppressed the differentiation of Th1 and Th17 cells, thus protecting against EAN. These effects collectively contribute to modifying the inflammatory environment and enhancing outcomes in EAN rats. CONCLUSIONS Suppression of P2X7R relieved EAN manifestation by regulating CD4+ T cell differentiation and NLRP3 inflammasome activation. This finding underscores the potential significance of P2X7R as a target for anti-inflammatory treatments, advancing research and management of GBS.
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Affiliation(s)
- Yuhan Xie
- Department of Neurology, Tianjin Nankai Hospital, Tianjin Medical University, Tianjin, 300052, China
- Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Ranran Han
- Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Yulin Li
- Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Weiya Li
- Department of Neurology, Tianjin Nankai Hospital, Tianjin Medical University, Tianjin, 300052, China
- Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Shichao Zhang
- Department of Urology, Tianjin Institute of Urology, The Second Hospital of Tianjin Medical University, Tianjin, 300102, China
| | - Yu Wu
- Department of Neurology, Tianjin Nankai Hospital, Tianjin Medical University, Tianjin, 300052, China
| | - Yuexin Zhao
- Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Rongrong Liu
- Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Jie Wu
- Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Wei Jiang
- Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, 300052, China.
- Department of Radiology, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China.
| | - Xiuju Chen
- Department of Neurology, Tianjin Nankai Hospital, Tianjin Medical University, Tianjin, 300052, China.
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Sluyter R, Sophocleous RA, Stokes L. P2X receptors: Insights from the study of the domestic dog. Neuropharmacology 2023; 224:109358. [PMID: 36464207 DOI: 10.1016/j.neuropharm.2022.109358] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/23/2022] [Accepted: 11/28/2022] [Indexed: 12/03/2022]
Abstract
Fifty years ago, the late Geoffrey Burnstock described the concept of purinergic nerves and transmission bringing into existence the broader concepts of purinergic signaling including P2X receptors. These receptors are trimeric ligand-gated cation channels activated by extracellular adenosine 5'-triphosphate (ATP). P2X receptors have important roles in health and disease and continue to gain interest as potential therapeutic targets in inflammatory, neurological, cardiovascular and many other disorders including cancer. Current understanding of P2X receptors has largely arisen from the study of these receptors in humans and rodents, but additional insights have been obtained from the study of P2X receptors in the domestic dog, Canis familiaris. This review article will briefly introduce purinergic signaling and P2X receptors, before detailing the pharmacological profiles of the two recombinant canine P2X receptors studied to date, P2X7 and P2X4. The article will then describe the current state of knowledge concerning the distribution and function of the P2X receptor family in dogs. The article will also discuss the characterization of single nucleotide polymorphisms in the canine P2RX7 gene, and contrast this variation to the canine P2RX4 gene, which is largely conserved between dogs. Finally, this article will outline published examples of the use of dogs to study the pharmacokinetics of P2X7 and P2X3 antagonists, and how they have contributed to the preclinical testing of antagonists to human P2X7, CE-224,535, and human P2X3, Gefapixant (AF-219, MK-7264) and Eliapixant (BAY, 1817080), with Gefapixant gaining recent approval for use in the treatment of refractory chronic cough in humans. This article is part of the Special Issue on 'Purinergic Signaling: 50 years'.
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Affiliation(s)
- 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.
| | - Reece A Sophocleous
- 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
| | - Leanne Stokes
- School of Pharmacy, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
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6-Furopyridine Hexamethylene Amiloride Is a Non-Selective P2X7 Receptor Antagonist. Biomolecules 2022; 12:biom12091309. [PMID: 36139148 PMCID: PMC9496321 DOI: 10.3390/biom12091309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/12/2022] [Accepted: 09/13/2022] [Indexed: 11/17/2022] Open
Abstract
P2X7 is an extracellular adenosine 5′-triphopshate (ATP)-gated cation channel present on leukocytes, where its activation induces pro-inflammatory cytokine release and ectodomain shedding of cell surface molecules. Human P2X7 can be partially inhibited by amiloride and its derivatives at micromolar concentrations. This study aimed to screen a library of compounds derived from amiloride or its derivative 5-(N,N-hexamethylene) amiloride (HMA) to identify a potential P2X7 antagonist. 6-Furopyridine HMA (6-FPHMA) was identified as a novel P2X7 antagonist and was characterized further. 6-FPHMA impaired ATP-induced dye uptake into human RPMI8226 multiple myeloma cells and human P2X7-HEK293 cells, in a concentration-dependent, non-competitive manner. Likewise, 6-FPHMA blocked ATP-induced Ca2+ fluxes in human P2X7-HEK293 cells in a concentration-dependent, non-competitive manner. 6-FPHMA inhibited ATP-induced dye uptake into human T cells, and interleukin-1β release within human blood and CD23 shedding from RPMI8226 cells. 6-FPHMA also impaired ATP-induced dye uptake into murine P2X7- and canine P2X7-HEK293 cells. However, 6-FPHMA impaired ATP-induced Ca2+ fluxes in human P2X4-HEK293 cells and non-transfected HEK293 cells, which express native P2Y1, P2Y2 and P2Y4. In conclusion, 6-FPHMA inhibits P2X7 from multiple species. Its poor selectivity excludes its use as a specific P2X7 antagonist, but further study of amiloride derivatives as P2 receptor antagonists is warranted.
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Sophocleous RA, Miles NA, Ooi L, Sluyter R. P2Y 2 and P2X4 Receptors Mediate Ca 2+ Mobilization in DH82 Canine Macrophage Cells. Int J Mol Sci 2020; 21:ijms21228572. [PMID: 33202978 PMCID: PMC7696671 DOI: 10.3390/ijms21228572] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 11/11/2020] [Accepted: 11/12/2020] [Indexed: 02/08/2023] Open
Abstract
Purinergic receptors of the P2 subclass are commonly found in human and rodent macrophages where they can be activated by adenosine 5'-triphosphate (ATP) or uridine 5'-triphosphate (UTP) to mediate Ca2+ mobilization, resulting in downstream signalling to promote inflammation and pain. However, little is understood regarding these receptors in canine macrophages. To establish a macrophage model of canine P2 receptor signalling, the expression of these receptors in the DH82 canine macrophage cell line was determined by reverse transcription polymerase chain reaction (RT-PCR) and immunocytochemistry. P2 receptor function in DH82 cells was pharmacologically characterised using nucleotide-induced measurements of Fura-2 AM-bound intracellular Ca2+. RT-PCR revealed predominant expression of P2X4 receptors, while immunocytochemistry confirmed predominant expression of P2Y2 receptors, with low levels of P2X4 receptor expression. ATP and UTP induced robust Ca2+ responses in the absence or presence of extracellular Ca2+. ATP-induced responses were only partially inhibited by the P2X4 receptor antagonists, 2',3'-O-(2,4,6-trinitrophenyl)-ATP (TNP-ATP), paroxetine and 5-BDBD, but were strongly potentiated by ivermectin. UTP-induced responses were near completely inhibited by the P2Y2 receptor antagonists, suramin and AR-C118925. P2Y2 receptor-mediated Ca2+ mobilization was inhibited by U-73122 and 2-aminoethoxydiphenyl borate (2-APB), indicating P2Y2 receptor coupling to the phospholipase C and inositol triphosphate signal transduction pathway. Together this data demonstrates, for the first time, the expression of functional P2 receptors in DH82 canine macrophage cells and identifies a potential cell model for studying macrophage-mediated purinergic signalling in inflammation and pain in dogs.
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Affiliation(s)
- Reece Andrew Sophocleous
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (R.A.S.); (N.A.M.); (L.O.)
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Nicole Ashleigh Miles
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (R.A.S.); (N.A.M.); (L.O.)
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Lezanne Ooi
- Illawarra Health and Medical Research Institute, Wollongong, NSW 2522, Australia; (R.A.S.); (N.A.M.); (L.O.)
- 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; (R.A.S.); (N.A.M.); (L.O.)
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW 2522, Australia
- Correspondence: ; Tel.: +612-4221-5508
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Sophocleous RA, Sluyter V, Curtis BL, Curtis SJ, Jurak LM, Faulks M, Spildrejorde M, Gates S, Proctor EJ, Seavers A, Watson D, Kuit T, Dowton M, Stokes L, Sluyter R. Association of a P2RX7 gene missense variant with brachycephalic dog breeds. Anim Genet 2019; 51:127-131. [PMID: 31774195 DOI: 10.1111/age.12884] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2019] [Indexed: 12/16/2022]
Abstract
Missense variants are associated with various phenotypic traits and disorders in dogs. The canine P2RX7 gene, coding the ATP-gated P2X7 receptor ion channel, contains four known missense variants. The current study aimed to examine the presence of these variants in a random sample of pedigree and mixed-pedigree dogs. Exons 3, 8, 11 and 13 of the P2RX7 gene, encoding these four respective variants, in 65 dogs were assessed by Sanger sequencing and combined with existing sequencing data from another 69 dogs. The distribution of these variants was then evaluated in all 134 dogs combined and separately within individual breeds including 35 different pure breeds. The rs23314713 (p.Phe103Leu) and rs23315462 (p.Pro452Ser) variants were present in 47 and 40% of all dogs studied respectively, with the rs23314713 variant associated with brachycephalic breeds. Among pedigree dogs, the rs23314713 and rs23315462 variants were associated with brachycephalic and non-brachycephalic breeds respectively. The rs851148233 (p.Arg270Cys) and rs850760787 (p.Arg365Gln) variants were present only in dogs of Cocker Spaniel and Labrador Retriever pedigrees respectively. No other missense variants were found in exons 3, 8, 11 and 13 of the P2RX7 gene within the dogs. In conclusion, the rs23314713 and rs23315462 missense variants of the P2RX7 gene are present in a large proportion of dogs, with the rs23314713 variant associated with a number of brachycephalic breeds. However, the association of this variant with dogs of bulldog ancestry, not brachycephaly per se, cannot be excluded.
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Affiliation(s)
- R A Sophocleous
- 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
| | - V 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
| | - B L Curtis
- Albion Park Veterinary Hospital, Albion Park, NSW, 2527, Australia
| | - S J Curtis
- Albion Park Veterinary Hospital, Albion Park, NSW, 2527, Australia
| | - L M Jurak
- 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
| | - M Faulks
- 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
| | - M Spildrejorde
- 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
| | - S Gates
- 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
| | - E-J Proctor
- 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
| | - A Seavers
- Oak Flats Veterinary Clinic, Oak Flats, NSW, 2529, Australia
| | - D Watson
- 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
| | - T Kuit
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - M Dowton
- 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
| | - L Stokes
- School of Pharmacy, University of East Anglia, Norwich, NR4 7TJ, UK
| | - R 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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Adhikary SR, Geraghty NJ, Cuthbertson P, Sluyter R, Watson D. Altered donor P2X7 activity in human leukocytes correlates with P2RX7 genotype but does not affect the development of graft-versus-host disease in humanised mice. Purinergic Signal 2019; 15:177-192. [PMID: 31001750 DOI: 10.1007/s11302-019-09651-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 03/04/2019] [Indexed: 01/08/2023] Open
Abstract
Graft-versus-host disease (GVHD) is a life-threatening consequence of allogeneic haematopoietic stem cell transplantation, a curative therapy for haematological malignancies. The ATP-gated P2X7 receptor channel is implicated in the development of GVHD. P2X7 activity on human leukocytes can be influenced by gain-of-function (GOF) and loss-of-function (LOF) single nucleotide polymorphisms (SNPs) in the P2RX7 gene. In this study, the P2RX7 gene was sequenced in 25 human donors and the P2X7 activity on subsets of peripheral blood T cells, natural killer (NK) cells and monocytes was measured using an ATP-induced dye uptake assay. GOF and LOF SNPs representing 10 of the 17 known P2RX7 haplotypes were identified, and correlated with P2X7 activity on all leukocyte subsets investigated. Notably, invariant (i) NK T cells displayed the highest P2X7 activity amongst all cell types studied. To determine if donor P2X7 activity influenced the development of GVHD, immunodeficient NOD-SCID-IL2Rγnull (NSG) mice were injected with human peripheral blood mononuclear cells isolated from donors of either GOF (hP2X7GOF mice) or LOF (hP2X7LOF mice) P2RX7 genotype. Both hP2X7GOF and hP2X7LOF mice demonstrated similar human leukocyte engraftment, and showed comparable weight loss, GVHD clinical score and overall survival. Donor P2X7 activity did not affect human leukocyte infiltration or GVHD-mediated tissue damage, or the relative expression of human P2X7 or human interferon-γ (hIFNγ) in tissues. Finally, hP2X7GOF and hP2X7LOF mice demonstrated similar concentrations of serum hIFNγ. This study demonstrates that P2X7 activity correlates with donor P2RX7 genotype on human leukocyte subsets important in GVHD development, but does not affect GVHD development in a humanised mouse model of this disease.
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Affiliation(s)
- S R Adhikary
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia.,Molecular Horizons, University of Wollongong, Wollongong, NSW, 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia
| | - N J Geraghty
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia.,Molecular Horizons, University of Wollongong, Wollongong, NSW, 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia
| | - P Cuthbertson
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia.,Molecular Horizons, University of Wollongong, Wollongong, NSW, 2522, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia
| | - R Sluyter
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Molecular Horizons, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
| | - D Watson
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Molecular Horizons, University of Wollongong, Wollongong, NSW, 2522, Australia. .,Illawarra Health and Medical Research Institute, Wollongong, NSW, 2522, Australia.
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Bartlett R, Stokes L, Curtis SJ, Curtis BL, Sluyter R. Probenecid directly impairs activation of the canine P2X7 receptor. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2017; 36:736-744. [PMID: 29200326 DOI: 10.1080/15257770.2017.1391395] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The current study aimed to determine if probenecid could directly impair the canine P2X7 receptor, a ligand-gated cation channel activated by extracellular adenosine 5'-triphosphate (ATP). Patch clamp measurements demonstrated that probenecid impairs ATP-induced inward currents in HEK-293 cells expressing canine P2X7. Flow cytometric measurements of ethidium+ uptake into HEK-293 cells expressing canine P2X7 showed that probenecid impairs ATP-induced pore formation in a concentration-dependent manner, with a half maximal inhibitory concentration of 158 µM. Finally, ELISA measurements revealed that probenecid impairs ATP-induced interleukin-1β release in dog blood. In conclusion, this study reveals that probenecid can directly impair canine P2X7 activation.
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Affiliation(s)
- Rachael Bartlett
- a School of Biological Sciences, University of Wollongong , Wollongong , NSW , Australia.,b Centre for Medical and Molecular Bioscience, University of Wollongong , Wollongong , NSW , Australia.,c Illawarra Health and Medical Research Institute , Wollongong , NSW , Australia
| | - Leanne Stokes
- d School of Pharmacy, University of East Anglia , Norwich , United Kingdom
| | - Stephen J Curtis
- e Albion Park Veterinary Hospital , Albion Park , NSW , Australia
| | - Belinda L Curtis
- e Albion Park Veterinary Hospital , Albion Park , NSW , Australia
| | - Ronald Sluyter
- a School of Biological Sciences, University of Wollongong , Wollongong , NSW , Australia.,b Centre for Medical and Molecular Bioscience, University of Wollongong , Wollongong , NSW , Australia.,c Illawarra Health and Medical Research Institute , Wollongong , NSW , Australia
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Faulks M, Kuit TA, Sophocleous RA, Curtis BL, Curtis SJ, Jurak LM, Sluyter R. P2X7 receptor activation causes phosphatidylserine exposure in canine erythrocytes. World J Hematol 2016; 5:88-93. [DOI: 10.5315/wjh.v5.i4.88] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 08/10/2016] [Accepted: 09/22/2016] [Indexed: 02/05/2023] Open
Abstract
AIM To determine if activation of the ATP-gated P2X7 receptor channel induces phosphatidylserine (PS) exposure in erythrocytes from multiple dog breeds.
METHODS Peripheral blood was collected from 25 dogs representing 13 pedigrees and seven crossbreeds. ATP-induced PS exposure on canine erythrocytes in vitro was assessed using a flow cytometric Annexin V binding assay.
RESULTS ATP induced PS exposure in erythrocytes from all dogs studied. ATP caused PS exposure in a concentration-dependent manner with an EC50 value of 395 μmol/L. The non-P2X7 agonists, ADP or AMP, did not cause PS exposure. The P2X7 antagonist, AZ10606120, but not the P2X1 antagonist, NF449, blocked ATP-induced PS exposure.
CONCLUSION The results indicate that ATP induces PS exposure in erythrocytes from various dog breeds and that this process is mediated by P2X7 activation.
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Burnstock G. Blood cells: an historical account of the roles of purinergic signalling. Purinergic Signal 2015; 11:411-34. [PMID: 26260710 PMCID: PMC4648797 DOI: 10.1007/s11302-015-9462-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 07/23/2015] [Indexed: 12/17/2022] Open
Abstract
The involvement of purinergic signalling in the physiology of erythrocytes, platelets and leukocytes was recognised early. The release of ATP and the expression of purinoceptors and ectonucleotidases on erythrocytes in health and disease are reviewed. The release of ATP and ADP from platelets and the expression and roles of P1, P2Y(1), P2Y(12) and P2X1 receptors on platelets are described. P2Y(1) and P2X(1) receptors mediate changes in platelet shape, while P2Y(12) receptors mediate platelet aggregation. The changes in the role of purinergic signalling in a variety of disease conditions are considered. The successful use of P2Y(12) receptor antagonists, such as clopidogrel and ticagrelor, for the treatment of thrombosis, myocardial infarction and stroke is discussed.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK.
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, Australia.
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Sluyter R. P2X and P2Y receptor signaling in red blood cells. Front Mol Biosci 2015; 2:60. [PMID: 26579528 PMCID: PMC4623207 DOI: 10.3389/fmolb.2015.00060] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 10/10/2015] [Indexed: 12/29/2022] Open
Abstract
Purinergic signaling involves the activation of cell surface P1 and P2 receptors by extracellular nucleosides and nucleotides such as adenosine and adenosine triphosphate (ATP), respectively. P2 receptors comprise P2X and P2Y receptors, and have well-established roles in leukocyte and platelet biology. Emerging evidence indicates important roles for these receptors in red blood cells. P2 receptor activation stimulates a number of signaling pathways in progenitor red blood cells resulting in microparticle release, reactive oxygen species formation, and apoptosis. Likewise, activation of P2 receptors in mature red blood cells stimulates signaling pathways mediating volume regulation, eicosanoid release, phosphatidylserine exposure, hemolysis, impaired ATP release, and susceptibility or resistance to infection. This review summarizes the distribution of P2 receptors in red blood cells, and outlines the functions of P2 receptor signaling in these cells and its implications in red blood cell biology.
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Affiliation(s)
- Ronald Sluyter
- School of Biological Sciences, University of WollongongWollongong, NSW, Australia
- Centre for Medical and Molecular Bioscience, University of WollongongWollongong, NSW, Australia
- Illawarra Health and Medical Research InstituteWollongong, NSW, Australia
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Sophocleous RA, Mullany PRF, Winter KM, Marks DC, Sluyter R. Propensity of red blood cells to undergo P2X7 receptor-mediated phosphatidylserine exposure does not alter during in vivo or ex vivo aging. Transfusion 2015; 55:1946-54. [PMID: 25823581 DOI: 10.1111/trf.13101] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 02/13/2015] [Accepted: 02/13/2015] [Indexed: 12/20/2022]
Abstract
BACKGROUND Phosphatidylserine (PS) exposure facilitates the removal of red blood cells (RBCs) from the circulation, potentially contributing to the loss of stored RBCs after transfusion, as well as senescent RBCs. Activation of the P2X7 receptor by extracellular adenosine 5'-triphosphate (ATP) can induce PS exposure on freshly isolated human RBCs, but whether this process occurs in stored RBCs or changes during RBC aging is unknown. STUDY DESIGN AND METHODS RBCs were processed and stored according to Australian blood banking guidelines. PS exposure was determined by annexin V binding and flow cytometry. Efficacy of P2X antagonists was assessed by flow cytometric measurements of ATP-induced ethidium+ uptake in RPMI 8226 cells. Osmotic fragility was assessed by lysis in hypotonic saline. RBCs were fractionated by discontinuous density centrifugation. RESULTS ATP (1 mmol/L) induced PS exposure on RBCs stored for less than 1 week. This process was near-completely inhibited by the P2X7 antagonists A438079 and AZ10606120 and the P2X1/P2X7 antagonist MRS2159 but not the P2X1 antagonist NF499. ATP-induced PS exposure on RBCs was not dependent on K+, Na+, or Cl- fluxes. ATP did not alter the osmotic fragility of stored RBCs. ATP-induced PS exposure was similar between RBCs of different densities. ATP-induced PS exposure was also similar between RBCs stored for less than 1 week or for 6 weeks. CONCLUSION The propensity of RBCs to undergo P2X7-mediated PS exposure does not alter during in vivo and ex vivo aging. Thus, P2X7 activation is unlikely to be involved in the removal of senescent RBCs or stored RBCs after transfusion.
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Affiliation(s)
- Reece A Sophocleous
- School of Biological Sciences.,Centre for Medical and Molecular Bioscience, University of Wollongong.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
| | - Phillip R F Mullany
- School of Biological Sciences.,Centre for Medical and Molecular Bioscience, University of Wollongong.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
| | - Kelly M Winter
- Research and Development, Australian Red Cross Blood Service, Sydney, NSW, Australia
| | - Denese C Marks
- Research and Development, Australian Red Cross Blood Service, Sydney, NSW, Australia
| | - Ronald Sluyter
- School of Biological Sciences.,Centre for Medical and Molecular Bioscience, University of Wollongong.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
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12
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Bartlett R, Stokes L, Sluyter R. The P2X7 receptor channel: recent developments and the use of P2X7 antagonists in models of disease. Pharmacol Rev 2015; 66:638-75. [PMID: 24928329 DOI: 10.1124/pr.113.008003] [Citation(s) in RCA: 313] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The P2X7 receptor is a trimeric ATP-gated cation channel found predominantly, but not exclusively, on immune cells. P2X7 activation results in a number of downstream events, including the release of proinflammatory mediators and cell death and proliferation. As such, P2X7 plays important roles in various inflammatory, immune, neurologic and musculoskeletal disorders. This review focuses on the use of P2X7 antagonists in rodent models of neurologic disease and injury, inflammation, and musculoskeletal and other disorders. The cloning and characterization of human, rat, mouse, guinea pig, dog, and Rhesus macaque P2X7, as well as recent observations regarding the gating and permeability of P2X7, are discussed. Furthermore, this review discusses polymorphic and splice variants of P2X7, as well as the generation and use of P2X7 knockout mice. Recent evidence for emerging signaling pathways downstream of P2X7 activation and the growing list of negative and positive modulators of P2X7 activation and expression are also described. In addition, the use of P2X7 antagonists in numerous rodent models of disease is extensively summarized. Finally, the use of P2X7 antagonists in clinical trials in humans and future directions exploring P2X7 as a therapeutic target are described.
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Affiliation(s)
- Rachael Bartlett
- School of Biological Sciences, University of Wollongong, New South Wales, Australia and Illawarra Health and Medical Research Institute, Wollongong, New South Wales, Australia (R.B., R.S.); and Health Innovations Research Institute, School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia (L.S.)
| | - Leanne Stokes
- School of Biological Sciences, University of Wollongong, New South Wales, Australia and Illawarra Health and Medical Research Institute, Wollongong, New South Wales, Australia (R.B., R.S.); and Health Innovations Research Institute, School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia (L.S.)
| | - Ronald Sluyter
- School of Biological Sciences, University of Wollongong, New South Wales, Australia and Illawarra Health and Medical Research Institute, Wollongong, New South Wales, Australia (R.B., R.S.); and Health Innovations Research Institute, School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia (L.S.)
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13
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Spildrejorde M, Bartlett R, Stokes L, Jalilian I, Peranec M, Sluyter V, Curtis BL, Skarratt KK, Skora A, Bakhsh T, Seavers A, McArthur JD, Dowton M, Sluyter R. R270C polymorphism leads to loss of function of the canine P2X7 receptor. Physiol Genomics 2014; 46:512-22. [PMID: 24824213 DOI: 10.1152/physiolgenomics.00195.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The relative function of the P2X7 receptor, an ATP-gated ion channel, varies between humans due to polymorphisms in the P2RX7 gene. This study aimed to assess the functional impact of P2X7 variation in a random sample of the canine population. Blood and genomic DNA were obtained from 69 dogs selected as representatives of a cross section of different breeds. P2X7 function was determined by flow cytometric measurements of dye uptake and patch-clamp measurements of inward currents. P2X7 expression was determined by immunoblotting and immunocytochemistry. Sequencing was used to identify P2RX7 gene polymorphisms. P2X7 was cloned from an English springer spaniel, and point mutations were introduced into this receptor by site-directed mutagenesis. The relative function of P2X7 on monocytes varied between individual dogs. The canine P2RX7 gene encoded four missense polymorphisms: F103L and P452S, found in heterozygous and homozygous dosage, and R270C and R365Q, found only in heterozygous dosage. Moreover, R270C and R365Q were associated with the cocker spaniel and Labrador retriever, respectively. F103L, R270C, and R365Q but not P452S corresponded to decreased P2X7 function in monocytes but did not explain the majority of differences in P2X7 function between dogs, indicating that other factors contribute to this variability. Heterologous expression of site-directed mutants of P2X7 in human embryonic kidney-293 cells indicated that the R270C mutant was nonfunctional, the F103L and R365Q mutants had partly reduced function, and the P452S mutant functioned normally. Taken together, these data highlight that a R270C polymorphism has major functional impact on canine P2X7.
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Affiliation(s)
- Mari Spildrejorde
- School of Biological Sciences, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia
| | - Rachael Bartlett
- School of Biological Sciences, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia
| | - Leanne Stokes
- Health Innovations Research Institute, School of Medical Sciences, RMIT University, Bundoora, Australia; Sydney Medical School Nepean, University of Sydney, Nepean Hospital, Penrith, Australia
| | - Iman Jalilian
- School of Biological Sciences, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia
| | - Michelle Peranec
- School of Biological Sciences, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia
| | - Vanessa Sluyter
- School of Biological Sciences, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia
| | | | - Kristen K Skarratt
- Sydney Medical School Nepean, University of Sydney, Nepean Hospital, Penrith, Australia
| | - Amanda Skora
- School of Biological Sciences, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia
| | - Tahani Bakhsh
- School of Biological Sciences, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia
| | - Aine Seavers
- Oak Flats Veterinary Clinic, Oak Flats, Australia
| | - Jason D McArthur
- School of Biological Sciences, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia
| | - Mark Dowton
- School of Biological Sciences, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia
| | - Ronald Sluyter
- School of Biological Sciences, University of Wollongong, Wollongong, Australia; Illawarra Health and Medical Research Institute, Wollongong, Australia;
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14
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Burnstock G. Introduction and perspective, historical note. Front Cell Neurosci 2013; 7:227. [PMID: 24312014 PMCID: PMC3836022 DOI: 10.3389/fncel.2013.00227] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 11/04/2013] [Indexed: 12/11/2022] Open
Abstract
P2 nucleotide receptors were proposed to consist of two subfamilies based on pharmacology in 1985, named P2X and P2Y receptors. Later, this was confirmed following cloning of the receptors for nucleotides and studies of transduction mechanisms in the early 1990s. P2X receptors are ion channels and seven subtypes are recognized that form trimeric homomultimers or heteromultimers. P2X receptors are involved in neuromuscular and synaptic neurotransmission and neuromodulation. They are also expressed on many types of non-neuronal cells to mediate smooth muscle contraction, secretion, and immune modulation. The emphasis in this review will be on the pathophysiology of P2X receptors and therapeutic potential of P2X receptor agonists and antagonists for neurodegenerative and inflammatory disorders, visceral and neuropathic pain, irritable bowel syndrome, diabetes, kidney failure, bladder incontinence and cancer, as well as disorders if the special senses, airways, skin, cardiovascular, and musculoskeletal systems.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical SchoolLondon, UK
- Department of Pharmacology, The University of MelbourneMelbourne, VIC, Australia
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15
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Jalilian I, Spildrejorde M, Seavers A, Curtis BL, McArthur JD, Sluyter R. Functional expression of the damage-associated molecular pattern receptor P2X7 on canine kidney epithelial cells. Vet Immunol Immunopathol 2012; 150:228-33. [DOI: 10.1016/j.vetimm.2012.09.040] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Revised: 09/10/2012] [Accepted: 09/28/2012] [Indexed: 11/25/2022]
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16
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P2X7 receptor activation induces reactive oxygen species formation in erythroid cells. Purinergic Signal 2012; 9:101-12. [PMID: 23014887 DOI: 10.1007/s11302-012-9335-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 09/12/2012] [Indexed: 10/27/2022] Open
Abstract
The presence of P2X7 on erythroid cells is well established, but its physiological role remains unclear. The current study aimed to determine if P2X7 activation induces reactive oxygen species (ROS) formation in murine erythroleukaemia (MEL) cells, a commonly used erythroid cell line. ATP induced ROS formation in a time- and concentration-dependent fashion. The most potent P2X7 agonist, 2'(3')-O-(4-benzoylbenzoyl)ATP, but not UTP or ADP, also induced ROS formation. The P2X7 antagonist, A-438079, impaired ATP-induced ROS formation. The ROS scavenger, N-acetyl-L-cysteine, and the ROS inhibitor, diphenyleneiodonium, also impaired P2X7-induced ROS formation, but use of enzyme-specific ROS inhibitors failed to identify the intracellular source of P2X7-induced ROS formation. P2X7-induced ROS formation was impaired partly by physiological concentrations of Ca(2+) and Mg(2+) and almost completely in cells in N-methyl-D-glucamine chloride medium. The p38 MAPK inhibitors SB202190 and SB203580, and the caspase inhibitor Z-VAD-FMK, but not N-acetyl-L-cysteine, impaired P2X7-induced MEL cell apoptosis. ATP also stimulated p38 MAPK and caspase activation, both of which could be impaired by A-438079. In conclusion, these findings indicate that P2X7 activation induces ROS formation in MEL cells and that this process may be involved in events downstream of P2X7 activation, other than apoptosis, in erythroid cells.
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17
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Wiley JS, Sluyter R, Gu BJ, Stokes L, Fuller SJ. The human P2X7 receptor and its role in innate immunity. ACTA ACUST UNITED AC 2012; 78:321-32. [PMID: 21988719 DOI: 10.1111/j.1399-0039.2011.01780.x] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The human P2X7 receptor is a two-transmembrane ionotropic receptor which has a ubiquitous distribution and is most highly expressed on immune cells. In macrophages and similar myeloid cells primed by lipopolysaccharide (LPS), activation of P2X7 by extracellular ATP opens a cation channel/pore allowing massive K+ efflux associated with processing and secretion of pro-inflammatory cytokines interleukin (IL)-1β and IL-18. A variety of other downstream effects follows P2X7 activation over several minutes including shedding of certain surface molecules, membrane blebbing, microvesicle/exosome release and apoptosis of the cell. High concentrations of ATP (>100 µM) are required to activate P2X7 but it remains unclear where these levels exist, other than in inflammatory foci or confined spaces such as in bone. A variety of potent selective antagonists of P2X7 activation have recently become available, allowing clinical trials to be undertaken in inflammatory and immune-mediated disorders. Proteomic studies have shown that P2X7 exists as a large multiprotein complex which includes non-muscle myosin heavy chain and other elements of the cytoskeleton. In the absence of its ATP ligand and serum, P2X7 has an alternate function in the recognition and phagocytosis of non-opsonized foreign particles, including bacteria and apoptotic cells. The P2RX7 gene has many polymorphic variants and isoforms which increase or decrease function of the receptor. Genetic association studies have linked loss-of-function polymorphisms with reactivation of latent tuberculosis as well as symptomatic infection with certain other obligate intracellular pathogens. The many roles involving P2X7 suggest that this receptor is essential to fundamental aspects of the innate immune response.
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Affiliation(s)
- J S Wiley
- Ion Channels and Disease Section, Florey Neuroscience Institutes, University of Melbourne, Parkville, Victoria, Australia.
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18
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Activation of the damage-associated molecular pattern receptor P2X7 induces interleukin-1β release from canine monocytes. Vet Immunol Immunopathol 2012; 149:86-91. [PMID: 22652409 DOI: 10.1016/j.vetimm.2012.05.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Revised: 04/27/2012] [Accepted: 05/02/2012] [Indexed: 02/07/2023]
Abstract
P2X7, a damage-associated molecular pattern receptor and adenosine 5'-triphosphate (ATP)-gated cation channel, plays an important role in the activation of the NALP3 inflammasome and subsequent release of interleukin (IL)-1β from human monocytes; however its role in monocytes from other species including the dog remains poorly defined. This study investigated the role of P2X7 in canine monocytes, including its role in IL-1β release. A fixed-time flow cytometric assay demonstrated that activation of P2X7 by extracellular ATP induces the uptake of the organic cation, YO-PRO-1(2+), into peripheral blood monocytes from various dog breeds, a process impaired by the specific P2X7 antagonist, A438079. Moreover, in five different breeds, relative P2X7 function in monocytes was about half that of peripheral blood T cells but similar to that of peripheral blood B cells. Reverse transcription-PCR demonstrated the presence of P2X7, NALP3, caspase-1 and IL-1β in LPS-primed canine monocytes. Immunoblotting confirmed the presence of P2X7 in LPS-primed canine monocytes. Finally, extracellular ATP induced YO-PRO-1(2+) uptake into and IL-1β release from these cells, with both processes impaired by A438079. These results demonstrate that P2X7 activation induces the uptake of organic cations into and the release of IL-1β from canine monocytes. These findings indicate that P2X7 may play an important role in IL-1β-dependent processes in dogs.
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19
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Tran JNSN, Pupovac A, Taylor RM, Wiley JS, Byrne SN, Sluyter R. Murine epidermal Langerhans cells and keratinocytes express functional P2X7 receptors. Exp Dermatol 2011; 19:e151-7. [PMID: 20113349 DOI: 10.1111/j.1600-0625.2009.01029.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Extracellular ATP via the activation of purinergic P2 receptors has an emerging role in cutaneous biology; however, the distribution of these receptors in mouse skin is poorly defined. This study investigated whether murine epidermal cell subpopulations express functional purinergic P2X(7) receptors. P2X(7) expression was examined by immunoblotting and immunofluorescence staining of epidermal cells from C57Bl/6 mice. P2X(7) function was evaluated by nucleotide-induced ethidium(+) uptake measurements in epidermal cells from C57Bl/6 mice, and from P2X(7) deficient mice and wild-type littermate controls. P2X(7) was detected in whole epidermal cell preparations, and specifically on Langerhans cells (LCs) and keratinocytes (KCs). ATP induced ethidium(+) uptake into LCs and KCs, with EC(50) values of 503 and 482 microm, respectively. BzATP, and to a lesser extent ATPgammaS and ADP, also induced ethidium(+) uptake; while UTP, alphabeta-meth-ATP and NAD were ineffective. ATP-induced ethidium(+) uptake was impaired by Na(+) and Mg(2+), and the P2X(7) antagonist, A-438079 and was absent in LCs and KCs from P2X(7) deficient mice. These results demonstrate that murine LCs and KCs express functional P2X(7), and support a role for this receptor in cutaneous biology.
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Affiliation(s)
- Jimmy N S N Tran
- Department of Medicine, Nepean Clinical School, University of Sydney, Penrith, NSW, Australia
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20
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Burnstock G, Kennedy C. P2X receptors in health and disease. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2011; 61:333-372. [PMID: 21586364 DOI: 10.1016/b978-0-12-385526-8.00011-4] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Seven P2X receptor subunits have been cloned which form functional homo- and heterotrimers. These are cation-selective channels, equally permeable to Na(+) and K(+) and with significant Ca(2+) permeability. The three-dimensional structure of the P2X receptor is described. The channel pore is formed by the α-helical transmembrane spanning region 2 of each subunit. When ATP binds to a P2X receptor, the pore opens within milliseconds, allowing the cations to flow. P2X receptors are expressed on both central and peripheral neurons, where they are involved in neuromuscular and synaptic neurotransmission and neuromodulation. They are also expressed in most types of nonneuronal cells and mediate a wide range of actions, such as contraction of smooth muscle, secretion, and immunomodulation. Changes in the expression of P2X receptors have been characterized in many pathological conditions of the cardiovascular, gastrointestinal, respiratory, and urinogenital systems and in the brain and special senses. The therapeutic potential of P2X receptor agonists and antagonists is currently being investigated in a range of disorders, including chronic neuropathic and inflammatory pain, depression, cystic fibrosis, dry eye, irritable bowel syndrome, interstitial cystitis, dysfunctional urinary bladder, and cancer.
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Affiliation(s)
- G Burnstock
- Autonomic Neuroscience Centre, University College Medical School, London, United Kingdom
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21
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Gadeock S, Tran JNSN, Georgiou JG, Jalilian I, Taylor RM, Wiley JS, Sluyter R. TGF-β1 prevents up-regulation of the P2X7 receptor by IFN-γ and LPS in leukemic THP-1 monocytes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:2058-66. [PMID: 20670615 DOI: 10.1016/j.bbamem.2010.07.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 07/20/2010] [Accepted: 07/21/2010] [Indexed: 11/15/2022]
Abstract
The P2X7 receptor is an extracellular ATP-gated cation channel critical in inflammation and immunity, and can be up-regulated by IFN-γ and LPS. This study aimed to examine the effect of TGF-β1 on the up-regulation of P2X7 function and expression in leukemic THP-1 monocytes differentiated with IFN-γ and LPS. Cell-surface molecules including P2X7 were examined by immunofluorescence staining. Total P2X7 protein and mRNA was assessed by immunoblotting and RT-PCR respectively. P2X7 function was evaluated by ATP-induced cation dye uptake measurements. Cell-surface P2X7 was present on THP-1 cells differentiated for 3days with IFN-γ and LPS but not on undifferentiated THP-1 cells. ATP induced ethidium(+) uptake into differentiated but not undifferentiated THP-1 cells, and the P2X7 antagonist, KN-62, impaired ATP-induced ethidium(+) uptake. Co-incubation of cells with TGF-β1 plus IFN-γ and LPS prevented the up-regulation of P2X7 expression and ATP-induced ethidium(+) uptake in a concentration-dependent fashion with a maximum effect at 5ng/ml and with an IC(50) of ~0.4ng/ml. Moreover, ATP-induced YO-PRO-1(2+) uptake and IL-1β release were abrogated in cells co-incubated with TGF-β1. TGF-β1 also abrogated the amount of total P2X7 protein and mRNA induced by IFN-γ and LPS. Finally, TGF-β1 prevented the up-regulation of cell-surface CD86, but not CD14 and MHC class II, by IFN-γ and LPS. These results indicate that TGF-β1 prevents the up-regulation of P2X7 function and expression by IFN-γ and LPS in THP-1 monocytes. This suggests that TGF-β1 may limit P2X7-mediated processes in inflammation and immunity.
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Affiliation(s)
- Safina Gadeock
- School of Biological Sciences, University of Wollongong, Wollongong, New South Wales, Australia
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22
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Constantinescu P, Wang B, Kovacevic K, Jalilian I, Bosman GJCGM, Wiley JS, Sluyter R. P2X7 receptor activation induces cell death and microparticle release in murine erythroleukemia cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1797-804. [PMID: 20529664 DOI: 10.1016/j.bbamem.2010.06.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 05/17/2010] [Accepted: 06/01/2010] [Indexed: 01/10/2023]
Abstract
Extracellular ATP induces cation fluxes in and impairs the growth of murine erythroleukemia (MEL) cells in a manner characteristic of the purinergic P2X7 receptor, however the presence of P2X7 in these cells is unknown. This study investigated whether MEL cells express functional P2X7. RT-PCR, immunoblotting and immunofluorescence staining demonstrated the presence of P2X7 in MEL cells. Cytofluorometric measurements demonstrated that ATP induced ethidium+ uptake into MEL cells in a concentration-dependent fashion and with an EC(50) of approximately 154 microM. The most potent P2X7 agonist 2'- and 3'-0(4-benzoylbenzoyl) ATP, but not ADP or UTP, induced ethidium+ uptake. ATP-induced ethidium+ and YO-PRO-1(2+) uptake were impaired by the P2X7 antagonist, A-438079. A colourmetric assay demonstrated that ATP impaired MEL cell growth. A cytofluorometric assay showed that ATP induced MEL cell death and that this process was impaired by A-438079. Finally, cytofluorometric measurements of Annexin-V binding and bio-maleimide staining demonstrated that ATP could induce rapid phosphatidylserine exposure and microparticle release in MEL cells respectively, both of which were impaired by A-438079. These results demonstrate that MEL cells express functional P2X7, and indicate that activation of this receptor may be important in the death and release of microparticles from red blood cells in vivo.
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