title: Strains of Group B streptococci from septic patients induce platelet activation via Toll-like Receptor 2.
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.
authors.affiliation: Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Hongyun
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Xianming
authors.initials: X
authors.lastname: Luo
authors.affiliation: Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Yanmin
authors.initials: Y
authors.lastname: Gao
authors.affiliation: Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Shuangfeng
authors.initials: S
authors.lastname: Xie
authors.affiliation: Department of General surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Kang
authors.initials: K
authors.lastname: Xu
authors.affiliation: Department of General surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Jianxing
authors.initials: J
authors.lastname: Chang
authors.affiliation: Department of Hematology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Ma
mesh_terms: D001792:Blood Platelets / Q000382:microbiology*; D015153:Blotting, Western; D005434:Flow Cytometry; D006801:Humans; D015539:Platelet Activation; D010974:Platelet Aggregation; D060888:Real-Time Polymerase Chain Reaction; D018805:Sepsis / Q000097:blood* / Q000378:metabolism / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000302:isolation & purification* / Q000472:pathogenicity; D013921:Thrombocytopenia / Q000097:blood / Q000382:microbiology; D051195:Toll-Like Receptor 2 / Q000378:metabolism*
chemical_list: D051195:Toll-Like Receptor 2
keywords: group B Streptococcus; platelet; platelet activation; sepsis; toll-like receptor