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Liu X, Liu H, Luo X, Zhang P, Gao Y, Xie S, Xu K, Chang J, Ma L. Strains of Group B streptococci from septic patients induce platelet activation via Toll-like Receptor 2. Clin Exp Pharmacol Physiol 2017; 44:335-343. [PMID: 27885699 DOI: 10.1111/1440-1681.12707] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 11/16/2016] [Accepted: 11/19/2016] [Indexed: 11/28/2022]
Abstract
Group B Streptococcus (GBS) causes life-threatening bacterial sepsis, especially in newborns and pregnant women. Patients suffering from sepsis often display low platelet counts, characterized by thrombocytopenia, because of platelet activation. In the present study, the roles of six GBS strains from septic patients in platelet aggregation, as well as the underlying mechanisms, were investigated. Incubation of platelets with three of the strains induced platelet aggregation, increased the secretion of cellular adhesin molecule CD62P and activation of GPIIb/IIIa. Furthermore, the GBS strains that induced platelet activation also caused an increase in the expression of Toll-like receptor (TLR) 2 in platelets. Pre-incubation of platelets with anti-TLR2 monoclonal antibody, but not anti-TLR4 monoclonal antibody, inhibited these functional responses induced by GBS. TLR2 stimulation also activated the phosphoinositide 3-kinase (PI3-K)/Akt signalling pathway in platelets, and inhibition of PI3-K significantly reduced GBS-induced platelet responses. Our results indicate that three of the GBS strains from the septic patients can trigger platelet activation by interacting with platelets, which involves the elevation of platelet TLR2 expression.
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Affiliation(s)
- Xiaoyan Liu
- Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Hongyun Liu
- Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Xianming Luo
- Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Ping Zhang
- Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Yanmin Gao
- Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Shuangfeng Xie
- Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Kang Xu
- Department of General surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Jianxing Chang
- Department of General surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Liping Ma
- Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
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Pietrocola G, Schubert A, Visai L, Torti M, Fitzgerald JR, Foster TJ, Reinscheid DJ, Speziale P. FbsA, a fibrinogen-binding protein from Streptococcus agalactiae, mediates platelet aggregation. Blood 2004; 105:1052-9. [PMID: 15383464 DOI: 10.1182/blood-2004-06-2149] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bacterium Streptococcus agalactiae is an etiologic agent in the pathogenesis of endocarditis in humans. FbsA, a fibrinogen-binding protein produced by this pathogen, is considered an important virulence factor. In the present study we provide evidence that S agalactiae clinical isolates bearing FbsA attach to fibrinogen and elicit a fibrinogen-dependent aggregation of platelets. Mutants of S agalactiae lacking the fbsA gene lost the ability to attach to fibrinogen and to aggregate platelets. Plasmid-mediated expression of fbsA restored the capability for fibrinogen binding and platelet aggregation in S agalactiae fbsA mutants, and allowed Lactococcus lactis to interact with fibrinogen and to aggregate human platelets. Moreover, a monoclonal anti-FbsA antibody inhibited bacterial adherence to fibrinogen and S agalactiae-induced platelet aggregation. Platelet aggregation was inhibited by aspirin, prostaglandin E(1,) the peptide RGDS, and the antibody abciximab, demonstrating the specificity of platelet aggregation by S agalactiae and indicating an involvement of integrin glycoprotein IIb/IIIa in the induction of platelet aggregation. Aggregation was also dependent on anti-FbsA IgG and could be inhibited by an antibody against the platelet FcgammaRIIA receptor. These findings indicate that FbsA is a crucial factor in S agalactiae-induced platelet aggregation and may therefore play an important role in S agalactiae-induced endocarditis.
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Affiliation(s)
- Giampiero Pietrocola
- University of Pavia, Department of Biochemistry, Viale Taramelli 3/B 27100 Pavia, Italy
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Reams RY, Harrington DD, Glickman LT, Thacker HL, Bowersock TB. Fibrinohemorrhagic pneumonia in pigs naturally infected with Streptococcus suis. J Vet Diagn Invest 1995; 7:406-8. [PMID: 7578464 DOI: 10.1177/104063879500700323] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Affiliation(s)
- R Y Reams
- Department of Veterinary Pathobiology, Purdue University, West Lafayette, IN 47907, USA
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