title: Interplay between membrane cholesterol and ethanol differentially regulates neutrophil tether mechanics and rolling dynamics.
abstract: Using microfluidic assays at a 100 s⁻¹ wall shear rate, we examined the effects of ethanol on cholesterol-loaded neutrophils with respect to: (1) collision efficiency and membrane tethering to P-selectin-coated microbeads, (2) rolling on P-selectin-coated surfaces, and (3) primary and secondary interactions with neutrophils pre-adhered to intercellular adhesion molecule-1 (ICAM-1). Using methyl-β-cyclodextrin:cholesterol complexes, membrane cholesterol was increased over control by 4.6-fold (no ethanol), 3.6-fold (0.3% ethanol pre-loading), and 1.6-fold (0.3% ethanol post-loading). These treatments did not alter CD11b expression; however, PSGL-1 and L-selectin were lowered by cholesterol enrichment (±ethanol). Cholesterol enrichment enhanced microbead collision efficiency, which was abrogated by ethanol. Ethanol had no effect on elevation of tethering fraction by cholesterol enrichment. Incubation of cholesterol-loaded neutrophils with ethanol resulted in significantly longer membrane tethers, due to tether lifetime enhancement. On P-selectin-coated surfaces, cholesterol-enriched neutrophils exposed to ethanol rolled faster and with more variability than cholesterol-enriched neutrophils. Ethanol reduced homotypic collision efficiency of cholesterol-loaded neutrophils without effect on tethering fraction or secondary collision efficiency. Tether length during cholesterol-loaded neutrophil homotypic collisions was enhanced by ethanol, in part due to increased L-selectin/PSGL-1 bond tether lifetime. Overall, ethanol attenuated cholesterol-induced adhesion increases while increasing membrane fluidity as indicated by tether length.
authors.affiliation: Department of Bioengineering, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: M
authors.initials: M
authors.lastname: Furlow
authors.forename: S L
authors.initials: SL
authors.lastname: Diamond
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D002448:Cell Adhesion / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism* / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D006801:Humans; D036904:Leukocyte Rolling / Q000187:drug effects*; D055595:Mechanical Phenomena; D008863:Microspheres; D009504:Neutrophils / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D019007:P-Selectin / Q000378:metabolism
chemical_list: D019007:P-Selectin; D000431:Ethanol; D002784:Cholesterol