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ORIGINAL RESEARCH article

Front. Cell. Infect. Microbiol.
Sec. Microbes and Innate Immunity
Volume 14 - 2024 | doi: 10.3389/fcimb.2024.1405333

Biofilm-dispersed pneumococci induce elevated leukocyte and platelet activation

Provisionally accepted
Yashuan Chao Yashuan Chao 1,2*Martina Mørch Martina Mørch 1,2Anders P. Håkansson Anders P. Håkansson 3Oonagh Shannon Oonagh Shannon 1,2
  • 1 Division of Infection Medicine, Department of Clinical Sciences, Lund, Faculty of Medicine, Lund University, Lund, Sweden
  • 2 Section of Oral Biology, Faculty of Odontology, Malmö University, Malmö, Skåne, Sweden
  • 3 Division of Experimental Infection Medicine, Department of Translational Medicine, Faculty of Medicine, Lund University, Lund, Skane County, Sweden

The final, formatted version of the article will be published soon.

    Streptococcus pneumoniae (the pneumococcus) effectively colonizes the human nasopharynx, but can migrate to other host sites, causing infections such as pneumonia and sepsis. Previous studies indicate that pneumococci grown as biofilms have phenotypes of bacteria associated with colonization whereas bacteria released from biofilms in response to changes in the local environment (i.e., dispersed bacteria) represent populations with phenotypes associated with disease. How these niche-adapted populations interact with immune cells upon reaching the vascular compartment has not previously been studied. Here, we investigated neutrophil, monocyte, and platelet activation using ex vivo stimulation of whole blood and platelet-rich plasma with pneumococcal populations representing distinct stages of the infectious process (biofilm and dispersed bacteria) as well as conventional broth-grown culture (planktonic bacteria). Flow cytometry and ELISA were used to assess surface and soluble activation markers for neutrophil and monocyte activation, plateletneutrophil complex and platelet-monocyte complex formation, and platelet activation and responsiveness. Overall, we found that biofilm-derived bacteria (biofilm bacteria and dispersed bacteria) induced significant activation of neutrophils, monocytes, and platelets. In contrast, little to no activation was induced by planktonic bacteria. Platelets remained functional after stimulation with bacterial populations and the degree of responsiveness was inversely related to initial activation. Bacterial association with immune cells followed a similar pattern as activation. Differences in activation of and association with immune cells by biofilm-derived populations could be an important consideration for other pathogens that have a biofilm state. Gaining insight into how these bacterial populations interact with the host immune response may reveal immunomodulatory targets to interfere with disease development.

    Keywords: Leukocyte activation, Monocytes, Neutrophils, platelets, Platelet Activation, Streptococcus pneumoniae biofilm bacteria. Together, the combination of In the present study

    Received: 22 Mar 2024; Accepted: 18 Jul 2024.

    Copyright: © 2024 Chao, Mørch, Håkansson and Shannon. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Yashuan Chao, Division of Infection Medicine, Department of Clinical Sciences, Lund, Faculty of Medicine, Lund University, Lund, Sweden

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.