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Nel JG, Durandt C, Theron AJ, Tintinger GR, Pool R, Richards GA, Mitchell TJ, Feldman C, Anderson R. Pneumolysin mediates heterotypic aggregation of neutrophils and platelets in vitro. J Infect 2017; 74:599-608. [PMID: 28267572 DOI: 10.1016/j.jinf.2017.02.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 02/17/2017] [Accepted: 02/24/2017] [Indexed: 10/20/2022]
Abstract
OBJECTIVES Platelets orchestrate the inflammatory activities of neutrophils, possibly contributing to pulmonary and myocardial damage during severe pneumococcal infection. This study tested the hypothesis that the pneumococcal toxin, pneumolysin (Ply), activates production of platelet-activating factor (PAF) and thromboxane A2 (TxA2) by neutrophils, these bioactive lipids being potential mediators of neutrophil:platelet (NP) networking. METHODS The effects of recombinant Ply (10-80 ng mL-1) on the production of PAF and TxA2 by isolated neutrophils were measured using ELISA procedures, and NP aggregation by flow cytometry. RESULTS Exposure of neutrophils to Ply induced production of PAF and, to a lesser extent, TxA2, achieving statistical significance at ≥20 ng mL-1 of the toxin. In the case of NP interactions, Ply promoted heterotypic aggregation which was dependent on upregulation of P-selectin (CD62P) and activation of protease-activated receptor 1 (PAR1), attaining statistical significance at ≥10 ng mL-1 of the toxin, but did not involve either PAF or TxA2. CONCLUSION Ply induces synthesis of PAF and TxA2, by human neutrophils, neither of which appears to contribute to the formation of NP heterotypic aggregates in vitro, a process which is seemingly dependent on CD62P and PAR1. These pro-inflammatory activities of Ply may contribute to the pathogenesis of pulmonary and myocardial injury during severe pneumococcal infection.
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Affiliation(s)
- Jan G Nel
- Department of Haematology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa; Tshwane Academic Division of the National Health Laboratory Service, Pretoria, South Africa.
| | - Chrisna Durandt
- Institute for Cellular and Molecular Medicine, South African Medical Research Council Unit for Stem Cell Research, Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Annette J Theron
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Gregory R Tintinger
- Department of Internal Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Roger Pool
- Department of Haematology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa; Tshwane Academic Division of the National Health Laboratory Service, Pretoria, South Africa
| | - Guy A Richards
- Department of Critical Care, Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa; Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Timothy J Mitchell
- Institute of Microbiology and Infection, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Charles Feldman
- Division of Pulmonology, Department of Internal Medicine, Charlotte Maxeke Johannesburg Academic Hospital, Johannesburg, South Africa
| | - Ronald Anderson
- Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa; Institute for Cellular and Molecular Medicine, South African Medical Research Council Unit for Stem Cell Research, Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
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