1
|
Collado-Díaz V, Martinez-Cuesta MÁ, Blanch-Ruiz MA, Sánchez-López A, García-Martínez P, Peris JE, Usach I, Ivorra MD, Lacetera A, Martín-Santamaría S, Esplugues JV, Alvarez A. Abacavir Increases Purinergic P2X7 Receptor Activation by ATP: Does a Pro-inflammatory Synergism Underlie Its Cardiovascular Toxicity? Front Pharmacol 2021; 12:613449. [PMID: 33867979 PMCID: PMC8045785 DOI: 10.3389/fphar.2021.613449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 02/15/2021] [Indexed: 11/15/2022] Open
Abstract
The cardiovascular toxicity of Abacavir is related to its purinergic structure. Purinergic P2X7-receptors (P2X7R), characterized by activation by high concentrations of ATP and with high plasticity, seem implicated. We appraise the nature of the interplay between Abacavir and P2X7R in generating vascular inflammation. The effects of Abacavir on leukocyte-endothelium interactions were compared with those of its metabolite carbovir triphosphate (CBV-TP) or ATP in the presence of apyrase (ATP-ase) or A804598 (P2X7R-antagonist). CBV-TP and ATP levels were evaluated by HPLC, while binding of Abacavir, CBV-TP and ATP to P2X7R was assessed by radioligand and docking studies. Hypersensitivity studies explored a potential allosteric action of Abacavir. Clinical concentrations of Abacavir (20 µmol/L) induced leukocyte-endothelial cell interactions by specifically activating P2X7R, but the drug did not show affinity for the P2X7R ATP-binding site (site 1). CBV-TP levels were undetectable in Abacavir-treated cells, while those of ATP were unaltered. The effects of Abacavir were Apyrase-dependent, implying dependence on endogenous ATP. Exogenous ATP induced a profile of proinflammatory actions similar to Abacavir, but was not entirely P2X7R-dependent. Docking calculations suggested ATP-binding to sites 1 and 2, and Abacavir-binding only to allosteric site 2. A combination of concentrations of Abacavir (1 µmol/L) and ATP (0.1 µmol/L) that had no effect when administered separately induced leukocyte-endothelium interactions mediated by P2X7R and involving Connexin43 channels. Therefore, Abacavir acts as a positive allosteric modulator of P2X7R, turning low concentrations of endogenous ATP themselves incapable of stimulating P2X7R into a functional proinflammatory agonist of the receptor.
Collapse
Affiliation(s)
- Víctor Collado-Díaz
- Departamento de Farmacología, Facultad de Medicina, Universidad de Valencia, Valencia, Spain
| | - Maria Ángeles Martinez-Cuesta
- Departamento de Farmacología, Facultad de Medicina, Universidad de Valencia, Valencia, Spain.,CIBERehd, Valencia, Spain
| | | | - Ainhoa Sánchez-López
- Departamento de Farmacología, Facultad de Medicina, Universidad de Valencia, Valencia, Spain
| | | | - José E Peris
- Departamento de Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Valencia, Valencia, Spain
| | - Iris Usach
- Departamento de Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Valencia, Valencia, Spain
| | - Maria Dolores Ivorra
- Departamento de Farmacología, Facultad de Medicina, Universidad de Valencia, Valencia, Spain
| | - Alessandra Lacetera
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Sonsoles Martín-Santamaría
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Juan V Esplugues
- Departamento de Farmacología, Facultad de Medicina, Universidad de Valencia, Valencia, Spain.,CIBERehd, Valencia, Spain.,FISABIO- Fundación Hospital Universitario Dr. Peset, Valencia, Spain
| | - Angeles Alvarez
- Departamento de Farmacología, Facultad de Medicina, Universidad de Valencia, Valencia, Spain.,CIBERehd, Valencia, Spain
| |
Collapse
|
2
|
Pexa A, Deussen A. Modulation of ecto-5'-nucleotidase by phospholipids in human umbilical vein endothelial cells (HUVEC). Naunyn Schmiedebergs Arch Pharmacol 2005; 372:131-8. [PMID: 16200394 DOI: 10.1007/s00210-005-0002-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Accepted: 08/11/2005] [Indexed: 10/25/2022]
Abstract
Ecto-5'-nucleotidase, the major enzyme controlling extracellular adenosine production, can be activated by phospholipids, e.g. lysophosphatidylcholine (LPC). This study examined the structural requirements of phospholipids to evoke this enzyme activation and figured out two new activators of ecto-5'-nucleotidase: platelet activating factor (PAF) and sphingosylphosphorylcholine (SPC). Potential signal transduction pathways including an involvement of protein kinase C and PAF-receptor were evaluated on the model of human umbilical vein endothelial cells (HUVEC). Cells were pre-incubated with 10 microM of various phospholipids including lysophosphatidylcholine, beta-arachidonyl-gamma-palmityl-alpha-phosphatidylcholine, beta,gamma-dipalmityl-alpha-phosphatidyl-choline, beta,gamma-dipalmityl-alpha-phosphatidylethanolamine, beta,gamma-dipalmityl-alpha-phosphatidylserine, gamma-acyl-beta-lyso-alpha-phosphatidylethanolamine, beta-acetyl-gamma-O-hexadecyl-alpha-phosphatidylcholine (platelet activating factor), lysophosphatidylic acid, sphingosine-1-phosphate and sphingosylphosphorylcholine. In the cell supernatant the extracellular dephosphorylation rate of the fluorescent AMP-analogue 1,N6-etheno-5'AMP to 1,N6-etheno-adenosine was measured by HPLC. Out of these ten structurally related phospholipids only lysophosphatidylcholine, sphingosylphosphatidylcholine and platelet activating factor dose-dependently increased the activity of ecto-5'-nucleotidase. Pharmacological blocking experiments revealed that neither the activation of PAF-receptor nor of protein kinase C were important for mediating the activation of ecto-5'-nucleotidase. Thus, using information on the known molecular structures of tested phospholipids, a phosphatidylcholine residue in alpha-position and a short chain length fatty acid esterified in beta-position seem essential for activation of ecto-5'-nucleotidase by glycerophospholipids. Since all tested phospholipids have similar fatty acid chain lengths and residues in alpha-position, they should act similarly on membrane fluidity. It is concluded that the observed effects are not based on changes in membrane fluidity by the added phospholipids, but rather involve a yet to be determined phospholipid-receptor.
Collapse
Affiliation(s)
- Annette Pexa
- Department of Physiology, Medical Faculty Carl Gustav Carus, Room A20.016, MTZ, TU Dresden, Fetscherstr. 74, 01307, Dresden, Germany.
| | | |
Collapse
|
3
|
Heptinstall S, Johnson A, Glenn JR, White AE. Adenine nucleotide metabolism in human blood--important roles for leukocytes and erythrocytes. J Thromb Haemost 2005; 3:2331-9. [PMID: 16150046 DOI: 10.1111/j.1538-7836.2005.01489.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Adenosine diphosphate (ADP) released into blood induces platelet aggregation and contributes to hemostasis and thrombosis. Released ATP can also induce platelet aggregation and there is evidence that blood leukocytes and also erythrocytes play important roles in this. Rapid metabolism of ADP and ATP by endothelial cells is important in protecting platelets from their effects. Here we have performed a systematic investigation of adenine nucleotide metabolism in human blood and the involvement of blood cells. Conversion of ATP to ADP in blood was due almost exclusively to the presence of leukocytes; plasma, platelets and erythrocytes made little or no contribution. Mononuclear leukocytes (MNLs) and polymorphonuclear leukocytes (PMNLs) were equally effective. Conversion of ADP to AMP was also promoted by leukocytes, with no involvement of platelets or erythrocytes. Some ADP was also converted to ATP in blood, apparently via an enzyme present in plasma, but ATP was then rapidly removed by the leukocytes. Conversion of AMP to adenosine occurred via a plasma enzyme with little or no contribution from any cellular element. As expected, in blood the adenosine produced was removed very rapidly by erythrocytes and then converted to inosine and then hypoxanthine. In the absence of erythrocytes plasma supported only a slow conversion of adenosine to inosine and hypoxanthine, which was not influenced by platelets or leukocytes. This study has demonstrated that leukocytes and erythrocytes play a major role in adenine nucleotide metabolism in blood and that these cells, as well as endothelial cells, may be important determinants of the effects of ATP and ADP on platelets.
Collapse
Affiliation(s)
- S Heptinstall
- Centre for Integrated Systems Biology and Medicine, Institute of Clinical Research, University of Nottingham, UK.
| | | | | | | |
Collapse
|
4
|
Tumoricidal potential of native blood dendritic cells: direct tumor cell killing and activation of NK cell-mediated cytotoxicity. THE JOURNAL OF IMMUNOLOGY 2005; 174:4127-34. [PMID: 15778372 DOI: 10.4049/jimmunol.174.7.4127] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Dendritic cells (DCs) are characterized by their unique capacity for primary T cell activation, providing the opportunity for DC-based cancer vaccination protocols. Novel findings reveal that besides their role as potent inducers of tumor-specific T cells, human DCs display additional antitumor effects. Most of these data were obtained with monocyte-derived DCs, whereas studies investigating native blood DCs are limited. In the present study, we analyze the tumoricidal capacity of M-DC8(+) DCs, which represent a major subpopulation of human blood DCs. We demonstrate that IFN-gamma-stimulated M-DC8(+) DCs lyse different tumor cell lines but not normal cells. In addition, we show that tumor cells markedly enhance the production of TNF-alpha by M-DC8(+) DCs via cell-to-cell contact and that this molecule essentially contributes to the killing activity of M-DC8(+) DCs. Furthermore, we illustrate the ability of M-DC8(+) DCs to promote proliferation, IFN-gamma production, and tumor-directed cytotoxicity of NK cells. The M-DC8(+) DC-mediated enhancement of the tumoricidal potential of NK cells is mainly dependent on cell-to-cell contact. These results reveal that, in addition to their crucial role in activating tumor-specific T cells, blood DCs exhibit direct tumor cell killing and enhance the tumoricidal activity of NK cells. These findings point to the pivotal role of DCs in triggering innate and adaptive immune responses against tumors.
Collapse
|