Platelet-Derived Thrombospondin-1 Protects the Host During Acute Pulmonary Pseudomonas Aeruginosa Infection
Year: 2021
Type: conference-abstract
Abstract: INTRODUCTION -Pseudomonas aeruginosa (PA) is a major cause of acute lower respiratory tract infections in the intensive care unit.Acute PA pulmonary infections are characterized by tissue injury caused by the secretion of bacterial toxins and proteases that trigger directly lung injury and also exuberant neutrophilic inflammation.Thrombospondin-1 (TSP-1), a matricellular protein with immunomodulatory properties, prevents excessive lung inflammation and protects the host during acute PA infection.A major source of TSP-1 in circulation is platelets in both mice and humans, and TSP-1 is the most abundant protein on a per mass basis in platelet alpha-granules and may be released during tissue injury.Here, we hypothesized that platelet-specific TSP-1 protects the lungs during acute PA infection.METHODS -Thbs1 fl/fl mice were generated using CRISPR/Cas9 technology and bred with PF4cre + mice to yield platelet and megakaryocyte-specific TSP-1 deficient mice.To confirm TSP-1 deletion at the protein level, thrombin-stimulated platelet releasates from PF4cre + Thbs1 fl/fl mice were compared to platelet releasates generated from PF4cre neg Thbs1 fl/fl wildtype (WT) littermates, full body Thbs1 -/-mice, C57BL6 WT mice and recombinant TSP-1 by immunoblot using anti-TSP1 antibody.Age and sex matched PF4cre + Thbs1 fl/fl mice and PF4cre neg Thbs1 fl/fl WT littermates were intratracheally inoculated with PA14 (10 6 CFU) and bacterial clearance and lung inflammation were evaluated at 20 hours post-infection.RESULTS -Western blot analyses confirmed the deletion of TSP-1 from platelet releasates of PF4cre + Thbs1 fl/fl and full body Thbs1 -/-mice, but not from PF4cre neg Thbs1 fl/fl littermates or WT mice.During acute PA pulmonary infection, PF4cre + Thbs1 fl/fl showed increased lung bacterial burden and increased microvascular permeability by bronchoalveolar lavage (BAL) total protein measurements, with exaggerated BAL free neutrophil elastase activity but no difference in BAL total neutrophil counts.Notably, PF4-cre + Thbs1 fl/fl mice show increased lung G-CSF and IL-1βlevels but no difference in IL-17A, IL-6, and CXCL-1 production.CONCLUSION -Platelet-derived TSP-1 contributes to host defense against acute PA lung infection, tempers microvascular injury, and restrains neutrophilic proteolysis.Our data provides novel insights regarding how platelet factors shape lung injury and protects the host during acute respiratory infection.
Authors: H.F. Penaloza, S. Gonzalez-Ferrer, R. van der Geest, E. Meyler, M. Hulver, W. Bain, Z. Xiong, S. Gingras, J. Lee
Institution: University of Pittsburgh
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
OpenAlex ID: W4248502366