National Cholesterol Awareness Month Membrane Cholesterol Is a Biomechanical Regulator of Neutrophil Adhesion

Objective—The purpose of this study was to evaluate the role of membrane cholesterol on human neutrophil and HL-60 biomechanics, capture, rolling, and arrest to P-selectin– or IL-1–activated endothelium. Methods and Results—Methyl-cyclodextrin (M CD) removed up to 73% and 45% of membrane cholesterol from HL-60 cells and neutrophils, whereas M CD/cholesterol complexes resulted in maximum enrichment of 65% and 40%, respectively, above control levels. Cells were perfused at a venous wall shear rate of 100 s 1 over adherent P-selectin–coated 1m diameter beads, uncoated 10m diameter beads, P-selectin–coated surfaces, or activated endothelium. Elevated cholesterol enhanced capture efficiency to 1m beads and increased membrane tether growth rate by 1.5to 2-fold, whereas cholesterol depletion greatly reduced tether formation. Elevated cholesterol levels increased tether lifetime by 17% in neutrophils and adhesion lifetime by 63% in HL-60 cells. Deformation of cholesterol-enriched neutrophils increased the contact time with 10m beads by 32% and the contact area by 7-fold. On both P-selectin surfaces and endothelial-cell monolayers, cholesterol-enriched neutrophils rolled more slowly, more stably, and were more likely to firmly arrest. Cholesterol depletion resulted in opposite effects. Conclusions—Increasing membrane cholesterol enhanced membrane tether formation and whole cell deformability, contributing to slower, more stable rolling on P-selectin and increased firm arrest on activated endothelium. (Arterioscler Thromb Vasc Biol. 2009;29:1290-1297.)