Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 114, Issue 21, Pages E4213-E4222Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1619609114
Keywords
aggregation; thrombin; lipopolysaccharides; host defense peptides
Categories
Funding
- Ministry of Education, Youth and Sports of the Czech Republic [LM2015062]
- Swedish Research Council [2012-1883, 2012-1842]
- O. E. and Edla Johanssons Foundation
- Welander-Finsen Foundation
- Crafoord Foundation
- Osterlund Foundation
- Soderberg Foundation
- Knut and Alice Wallenberg Foundation
- Swedish Foundation for Strategic Research
- Swedish Government Funds for Clinical Research
- medical faculty of Lund University
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Effective control of endotoxins and bacteria is crucial for normal wound healing. During injury, the key enzyme thrombin is formed, leading to generation of fibrin. Here, we show that human neutrophil elastase cleaves thrombin, generating 11-kDa thrombin-derived C-terminal peptides (TCPs), which bind to and form amorphous amyloid-like aggregates with both bacterial lipopolysaccharide (LPS) and gram-negative bacteria. In silico molecular modeling using atomic resolution and coarse-grained simulations corroborates our experimental observations, altogether indicating increased aggregation through LPS-mediated intermolecular contacts between clusters of TCP molecules. Upon bacterial aggregation, recombinantly produced TCPs induce permeabilization of Escherichia coli and phagocytic uptake. TCPs of about 11 kDa are present in acute wound fluids as well as in fibrin sloughs from patients with infected wounds. We noted aggregation and colocalization of LPS with TCPs in such fibrin material, which indicates the presence of TCP-LPS aggregates under physiological conditions. Apart from identifying a function of proteolyzed thrombin and its fragments, our findings provide an interesting link between the coagulation system, innate immunity, LPS scavenging, and protein aggregation/amyloid formation.
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