Inhibition of immunothrombosis does not affect pathogen capture and does not promote bacterial dissemination in a mouse model of sepsis

Abstract

After infection, neutrophils release neutrophil extracellular traps (NETs), decondensed DNA fibers decorated with both nuclear proteins and proteins derived from intracellular granules. These structures have a fundamental role in the development of immunothrombosis; a physiological process mediated by immune cells and molecules from the coagulation system that facilitates the recognition, containment, and destruction of pathogens. Although NETs and immunothrombi are widely hypothesized to be key host defense responses responsible for limiting bacterial dissemination, their actual role in this process has not been formally assessed within the context of a bloodstream infection. Mice were first treated with LPS to generate inflammation (NETs and immunothrombi) and then bacteria dissemination was analyzed by intravital microscopy and colony-forming units (CFU) assay. Blocking NETs or coagulation by the administration of DNase or Argatroban (thrombin inhibitor), respectively, did not modify the percentage of bacteria capture by Kupffer cells, neutrophils or platelets. Moreover, both inhibitors reduced the number of bacteria in the spleen, without modifying CFUs in the liver or lung. In conclusion, we demonstrate that immunothrombi are not necessary to limit the dissemination of bloodstream bacterial infections.

Keywords:

• Bacteria
• coagulation
• immunotrhombosis
• infection
• neutrophil extracellular traps
• neutrophils

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by grants from the Canadian Foundation for Innovation, Alberta Innovates and Advanced Education, Heart and Stroke Foundation of Canada (HSFC) and the Natural Sciences and Engineering Research Council (NSERC) to CNJ. CNJ is supported by the Canada Research Chairs program. AC is supported by the Beverley Phillips Rising Star Postdoctoral Fellowship and the University of Calgary, Cumming School of Medicine Postdoctoral Scholar Program. RPD is funded by the Canadian Liver Foundation and the University of Calgary Faculty of Graduate Studies Indigenous Graduate Award. LD is funded by the Wellcome Trust Mechanisms of Inflammatory Disease (MIDAS) Doctoral Training Programme.