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Complement Activation Occurs at the Surface of Platelets Activated by Streptococcal M1 Protein and This Results in Phagocytosis of Platelets

Palm, Frida LU ; Sjöholm, Kristoffer LU ; Malmström, Johan LU and Shannon, Oonagh LU (2019) In Journal of immunology (Baltimore, Md. : 1950) 202(2). p.503-513
Abstract

Platelets circulate the bloodstream and principally maintain hemostasis. Disturbed hemostasis, a dysregulated inflammatory state, and a decreased platelet count are all hallmarks of severe invasive Streptococcus pyogenes infection, sepsis. We have previously demonstrated that the released M1 protein from S. pyogenes activates platelets, and this activation is dependent on the binding of M1 protein, fibrinogen, and M1-specific IgG to platelets in susceptible donors. In this study, we characterize the M1-associated protein interactions in human plasma and investigate the acquisition of proteins to the surface of activated platelets and the consequences for platelet immune function. Using quantitative mass spectrometry, M1 protein was... (More)

Platelets circulate the bloodstream and principally maintain hemostasis. Disturbed hemostasis, a dysregulated inflammatory state, and a decreased platelet count are all hallmarks of severe invasive Streptococcus pyogenes infection, sepsis. We have previously demonstrated that the released M1 protein from S. pyogenes activates platelets, and this activation is dependent on the binding of M1 protein, fibrinogen, and M1-specific IgG to platelets in susceptible donors. In this study, we characterize the M1-associated protein interactions in human plasma and investigate the acquisition of proteins to the surface of activated platelets and the consequences for platelet immune function. Using quantitative mass spectrometry, M1 protein was determined to form a protein complex in plasma with statistically significant enrichment of fibrinogen, IgG3, and complement components, especially C1q. Using flow cytometry, these plasma proteins were also confirmed to be acquired to the platelet surface, resulting in complement activation on M1-activated human platelets. Furthermore, we demonstrated an increased phagocytosis of M1-activated platelets by monocytes, which was not observed with other physiological platelet agonists. This reveals a novel mechanism of complement activation during streptococcal sepsis, which contributes to the platelet consumption that occurs in sepsis.

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author
organization
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type
Contribution to journal
publication status
published
subject
in
Journal of immunology (Baltimore, Md. : 1950)
volume
202
issue
2
pages
11 pages
publisher
American Association of Immunologists
external identifiers
  • pmid:30541884
  • scopus:85059925886
  • pmid:30541884
ISSN
1550-6606
DOI
10.4049/jimmunol.1800897https://doi.org/10.4049/jimmunol.1800897
language
English
LU publication?
yes
id
763781c7-1104-461c-af3c-79788a3d9974
date added to LUP
2019-01-01 17:58:53
date last changed
2020-01-22 07:23:05
@article{763781c7-1104-461c-af3c-79788a3d9974,
  abstract     = {<p>Platelets circulate the bloodstream and principally maintain hemostasis. Disturbed hemostasis, a dysregulated inflammatory state, and a decreased platelet count are all hallmarks of severe invasive Streptococcus pyogenes infection, sepsis. We have previously demonstrated that the released M1 protein from S. pyogenes activates platelets, and this activation is dependent on the binding of M1 protein, fibrinogen, and M1-specific IgG to platelets in susceptible donors. In this study, we characterize the M1-associated protein interactions in human plasma and investigate the acquisition of proteins to the surface of activated platelets and the consequences for platelet immune function. Using quantitative mass spectrometry, M1 protein was determined to form a protein complex in plasma with statistically significant enrichment of fibrinogen, IgG3, and complement components, especially C1q. Using flow cytometry, these plasma proteins were also confirmed to be acquired to the platelet surface, resulting in complement activation on M1-activated human platelets. Furthermore, we demonstrated an increased phagocytosis of M1-activated platelets by monocytes, which was not observed with other physiological platelet agonists. This reveals a novel mechanism of complement activation during streptococcal sepsis, which contributes to the platelet consumption that occurs in sepsis.</p>},
  author       = {Palm, Frida and Sjöholm, Kristoffer and Malmström, Johan and Shannon, Oonagh},
  issn         = {1550-6606},
  language     = {eng},
  month        = {01},
  number       = {2},
  pages        = {503--513},
  publisher    = {American Association of Immunologists},
  series       = {Journal of immunology (Baltimore, Md. : 1950)},
  title        = {Complement Activation Occurs at the Surface of Platelets Activated by Streptococcal M1 Protein and This Results in Phagocytosis of Platelets},
  url          = {http://dx.doi.org/10.4049/jimmunol.1800897https://doi.org/10.4049/jimmunol.1800897},
  doi          = {10.4049/jimmunol.1800897https://doi.org/10.4049/jimmunol.1800897},
  volume       = {202},
  year         = {2019},
}