IMPACT OF SELECTIN DENSITY ON MONOCYTE ADHESION STRENGTH

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Inflammation is classified as a physiological response to suppress pathological processes. This response is highly localized to literally destroy injured tissues, pathogens, etc and promote tissue healing/regeneration [1] Chronic inflammation can also lead to pathological immune responses, e.g. autoimmune diseases, and therefore therapies that suppress systemic inflammation would be beneficial[2]. Receptor-ligand interactions are critical for every step of an inflammatory response including neutrophil, monocyte, lymphocyte, and macrophage adhesion to vascular endothelial cells, transvascular migration (diapedesis) into inflamed tissues, and phagocytosis of foreign bodies, injured tissues, pathogens, etc. The objective of the parent grant is to develop a dextran-peptide conjugate that selectively binds injured tissue surfaces to form a protective colloid barrier against trauma-induced inflammatory cell damage to healthy tissues. Dr. Bowen has developed an e-selectin-binding dextran-peptide bioconjugate that has been shown to effectively inhibit monocyte adhesion to endothelial cells grown in culture that have been stimulated by tumor necrosis factor-¿ (TNF-¿)- (see preliminary results). A specific aim of the parent grant is to assess the effects of bioconjugate treatment on leukocyte adhesion to cultured endothelial cells subjected to physiological flow. In order to measure physical properties of e-selectin binding therapeutics, an in vitro experiment has been developed where cultured monocytes bind to substrates containing various densities of purified e-selectin. These measurements are made to understand the nature of the bioconjugate without confounding effects introduced by the endothelial cell such as internalization and membrane diffusion. In this collaboration we will use the 3-axis force clamp of the Spatially Modulated Microbeam (SMM) LAMMP core technology. We will measure the adhesion strength between monocytes and substrates coated with varying densities of e-selectin. We will first determine the relationship between e-selectin density and adhesion strength, and then determine the dosage of the dextran bioconjugate required to block monocyte adhesion to a substrate with varying densities of e-selectin. Results from this collaboration will provide fundamental knowledge of molecular interactions between monocyte and endothelial cell ligands as well as between prototype-bioconjugates and endothelial cell ligands. This information will be used to formulate dosing in in vivo animals studies.