title: Effects of physiologically relevant dynamic shear stress on platelet complement activation.
abstract: Disturbed shear stress, commonly found in cardiovascular diseases, plays important roles in platelet activation and functions. It has been reported that when activated by elevated shear stress, platelets were able to support complement activation to completion. In this study, through a dynamic cone and plate shearing device, three physiologically relevant shear stresses were applied to platelets, mimicking the shear conditions when platelets pass through a normal left coronary artery (0.05-1 Pa), a 60% stenosis (elevated shear stress at 6.5 Pa for less than 0.1 s), and when platelets are trapped in a recirculation zone past a stenosis (<0.5 Pa). After shear exposure, platelet-surface complement activation (C1q, C4d, iC3b, and SC5b-9 depositions) was measured using a solid-phase ELISA approach and flow cytometry. Production of complement regulatory proteins - C1-inhibitor (C1-INH) and complement receptor 1 (CR1), was also measured. Results demonstrated that low-pulsatile shear stress (recirculation) was able to initiate platelet complement activation, by increasing C1q deposition significantly. Both pathological shear stresses triggered significant increases in C1 inhibitor generation and noticeable changes in CR1 production, effectively preventing complement activation from completion. These results suggested that for platelets, low-pulsatile shear stress may be more pro-atherogenic, compared to elevated shear stress, especially when the shear stress exposure time is short.
authors.affiliation: School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, USA.
authors.forename: Saravan Kumar
authors.initials: SK
authors.lastname: Shanmugavelayudam
authors.forename: David A
authors.initials: DA
authors.lastname: Rubenstein
authors.forename: Wei
authors.initials: W
authors.lastname: Yin
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism / Q000494:pharmacology; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D003167:Complement Activation / Q000187:drug effects; D015922:Complement C1q / Q000378:metabolism; D003165:Complement System Proteins / Q000378:metabolism*; D006801:Humans; D015539:Platelet Activation / Q000187:drug effects; D011485:Protein Binding; D033081:Shear Strength; D013312:Stress, Physiological
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D000244:Adenosine Diphosphate; D015922:Complement C1q; D003165:Complement System Proteins