OC 35.2 - Spleen tyrosine kinase inhibition mitigates hemin-induced thrombo-inflammation and improves organ perfusion in sickle cell mice

Monday, June 24, 2024

09:45 – 10:00 ICT

Room: 110 A-C

Co-Author(s)

JE

Juma El Awaisi

Post doctoral fellow
University of Birmingham
Birmingham, England, United Kingdom
GP

Gina Perrella

Post doctoral fellow
University of Birmingham
Birmingham, England, United Kingdom
VT

Veronika Tinkova

PhD student
University of Birmingham
Birmingham, England, United Kingdom
BG

Beata Grygielska

Lab Technician
University of Birmingham
Birmingham, England, United Kingdom
NK

Neena Kalia

Reader
University of Birmingham
Birmingham, England, United Kingdom
SW

Steve P. Watson

Professor
University of Birmingham
Birmingham, England, United Kingdom
Alexander Brill

Associate Professor
University of Birmingham
Birmingham, England, United Kingdom
DK

Dean Kavanagh

Assistant Professor
University of Birmingham
Birmingham, England, United Kingdom

Presenting Author(s)

Julie Rayes, PhD

Associate Professor
University of Birmingham
Birmingham, England, United Kingdom

Background: Sickle cell disease (SCD) is characterized by hemolytic anemia, vaso-occlusive crisis, hypoperfusion, and progressive organ damage. The release of heme during hemolysis induces platelet activation through CLEC-2 and GPVI, endothelial activation through TLR4 and neutrophil adhesion and NETosis in SCD, all of which regulated by spleen tyrosine kinase (Syk).

Aims: This study investigates the effect of Syk inhibition on hemin-induced platelet and neutrophil recruitment and blood perfusion in different organs in humanized Berkeley sickle cell mice.

Methods: Neutrophil and platelet recruitment to the pulmonary, renal, splenic, and hepatic microvasculature was monitored by intravital microscopy at basal level and following hemin injection in control and SCD mice. Syk inhibitor, BI-1002494, was injected prior to heme in SCD mice. Organ perfusion was assessed by laser speckle contrast imaging.

Results: Compared to control, SCD mice exhibited higher baseline neutrophil and platelet recruitment to the lungs. Injection of hemin increased cell recruitment to the pulmonary vasculature in control and SCD mice with concurrent reduction in organ perfusion as assessed by laser speckle contrast imaging. Analysis of platelet and neutrophil recruitment over 1h of imaging showed an increase in cell recruitment and platelet embolism in SCD lung vasculature which was associated with reduced lung perfusion compared to control. A similar increase in platelet and neutrophil recruitment was observed in the kidney associated with reduced perfusion. Conversely, neutrophil recruitment to the liver and spleen following hemin injection was impaired in SCD mice compared to control without alteration in organ perfusion. Pretreatment of SCD mice with the Syk inhibitor BI-1002494 mitigated baseline and hemin-induced neutrophil and platelet adhesion recruitment to the pulmonary and renal microvasculature with corresponding normalization of perfusion.

Conclusion(s): These data substantiate Syk as a mediator of hemin-mediated thrombo-inflammation and hypoperfusion in the lung and kidney of SCD and provide a rationale for pharmacological inhibition as a therapeutic strategy.