title: Interactions between surface-bound actin and complement, platelets, and neutrophils.
abstract: Actin exists as globular (G) monomers or polymeric filaments (F) in the cytoplasm of eukaryotic cells, mediating cell morphologic changes and motility. Large amounts of this protein may be released out to the extracellular compartment during tissue injury, but little is known about its role in biomaterial-related inflammation. We immobilized actin to methylated glass, methylated and aminated silicon, and gold model surfaces and studied the subsequent blood serum deposition and complement activation, generation of reactive oxygen species (ROS), and adhesion and aggregation of neutrophils and platelets. Null ellipsometry showed that approximately one monolayer of G-actin can be immobilized onto the model surfaces and that actin in buffer polymerized on top of this by the addition of K(+) and Mg(2+) ions to form a thicker layer of firmly bound F-actin. After serum incubation, F-actin bound low amounts of anti-complement factor 1q (anti-C1q). Cell responses upon contact with actin-coated surfaces were analyzed by luminol-amplified chemiluminescence, lumi-aggregometry, and fluorescence microscopy. It was shown that surface-triggered aggregation, spreading, and generation of ROS are down-regulated and comparable to the response by adsorbed albumin. However, F-actin on gold surfaces recruited platelets in a C1q-dependent manner. We conclude that in vitro adsorbed actin is a weak complement, platelet, and neutrophil activator, but that F-actin associates with both C1q and platelets.
authors.affiliation: Division of Applied Physics, Department of Physics and Measurement Technology, Biology and Chemistry, Linköping University, SE-581 83 Linköping, Sweden. jonwe@ifm.liu.se
authors.forename: Jonas
authors.initials: J
authors.lastname: Wetterö
authors.forename: Agneta
authors.initials: A
authors.lastname: Askendal
authors.forename: Pentti
authors.initials: P
authors.lastname: Tengvall
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Bengtsson
mesh_terms: D000199:Actins / Q000378:metabolism* / Q000494:pharmacology; D000327:Adsorption; D000328:Adult; D000418:Albumins / Q000378:metabolism; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001704:Biopolymers; D001792:Blood Platelets / Q000378:metabolism*; D003167:Complement Activation / Q000187:drug effects*; D015922:Complement C1q / Q000378:metabolism*; D047630:Depsipeptides; D005898:Glass / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D008163:Luminescent Measurements; D008745:Methylation; D008856:Microscopy, Fluorescence; D009504:Neutrophils / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000494:pharmacology; D015539:Platelet Activation / Q000187:drug effects*; D011437:Propylamines; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism; D012821:Silanes / Q000737:chemistry; D012825:Silicon / Q000737:chemistry*; D013329:Structure-Activity Relationship
chemical_list: D000199:Actins; D000418:Albumins; D001672:Biocompatible Materials; D001704:Biopolymers; D047630:Depsipeptides; D007074:Immunoglobulin G; D010456:Peptides, Cyclic; D011437:Propylamines; D017382:Reactive Oxygen Species; D012821:Silanes; C057531:jasplakinolide; D006046:Gold; D015922:Complement C1q; C477625:amino-propyl-triethoxysilane; D012825:Silicon