a study on the effect of inflammatory cytokines on platelet-endothelial adhesion and activation in the parallel plate flow chamber

Open Access
- Author:
- Kwan, Jamie
- Graduate Program:
- Integrative and Biomedical Physiology
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 16, 2022
- Committee Members:
- Keefe B Manning, Thesis Advisor/Co-Advisor
Lacy Marie Alexander, Committee Member
Donna Korzick, Program Head/Chair
Peter Butler, Committee Member - Keywords:
- platelet
endothelial cell
endothelium
inflammation
cytokine
flow chamber
thrombosis - Abstract:
- Cardiovascular diseases continue to be the leading cause of death in the United States, affecting over 80 million people today. First-line treatments involve changes in lifestyle paired with some oral medications such as statins, blood thinners, beta blockers, and ACE inhibitors. However, when cases grow to be more severe, surgery becomes necessary to treat the condition. Some of the most common cardiovascular surgical procedures include angioplasty, bypass grafts, and valve replacements, but what they all have in common is that they result in vascular and/or myocardial injury and introduction to biomaterials, which induces an inflammatory response within the cardiovascular system. The damaged endothelium will become activated and express a prothrombotic profile, allowing the recruitment of leukocytes and binding of platelets. Studies have shown that surgical procedures result in high levels of pro-inflammatory cytokines, while promotes activation and adhesion in endothelial cells and platelets. In this study, we examined the effects of cytokines TNF-α and IL-1β on platelet-endothelial activation and adhesion in a parallel plate flow chamber. Expression of adhesion molecules integrin αVβ3 and ICAM-1 were measured as markers of endothelial cell activation and receptors in platelet binding. Platelet activation was indicated by P-selectin expression, and adhesion events were marked by CD41 (HIP2). Flow experiments were conducted with a flow rate (Q) of 80 μ/min and a shear rate (γ) of 200 s-1 for up to 30 minutes. Flow cytometry and confocal imaging were performed to quantify the activation and adhesion parameters. The outcomes of the study showed that TNF-α and IL-1β resulted in increased platelet activation over time with significantly a higher activation of >25% by 30 minutes for both treatment groups compared to about 18% in untreated platelets. Both also resulted in a greater number platelet adhesion events over the 30 minutes compared to the untreated. However, the endothelial adhesion markers involved differed. TNF-α did not induce increased expression of integrin αVβ3 but did result in increased ICAM-1 expression to the cell surface. IL-1β was responsible for the expression of both adhesion molecules to the membrane, indicating different mechanisms of both proinflammatory cytokines in stimulating endothelial cell activation. These studies would suggest a significant role of inflammation in activation and adhesion of platelets and the vascular endothelium, specifically involving integrin αVβ3 and ICAM-1 binding mechanisms. Future studies will continue to elucidate the role of these processes in vivo in surgeries used to treat various cardiovascular disease states.