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Adhésion et phagocytose de gouttes d'émulsions fonctionnalisées

Abstract : Phagocytosis by macrophages represents a fundamental process essential for both immunity and tissue homeostasis. The size of targets to be eliminated ranges from small particles as bacteria to large objects as cancerous or senescent cells. Most of our current quantitative knowledge on phagocytosis is based on the use of solid polymer microparticles as model targets that are well adapted to the study of phagocytosis mechanisms that do not involve any lateral mobility of the ligands, despite the relevance of this parameter in the immunological context. The aim of this study is to synthesize a biomimetic material that constitutes a new model system for the study of phagocytosis. We designed monodisperse, lateraly mobile IgG-coated emulsion droplets, with different controlled densities of IgGs, that are efficiently and specifically internalized by macrophages through in-vitro FcγR-mediated phagocytosis. The excellent control of the opsonization density allowed us to measure the minimal IgGs density required to induce an efficient internalization. We also attempted to deepen the understanding of certain mechanical aspects. We show that, contrary to solid polymeric beads, droplet uptake is high even for low IgG densities and is accompagnied by the clustering of the opsonins in the zone of contact with the macrophage during the adhesion step. Beyond the sole interest in the design of the material, our results suggest that lateral mobility of proteins at the interface of a target greatly enhances the phagocytic uptake. Thus, emulsion droplets constitute a new interesting target to investigate different biological issues and understand molecular and/or mechanical mechansims.
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Submitted on : Thursday, March 26, 2015 - 9:47:07 AM
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  • HAL Id : tel-01135846, version 1


Kalthoum Ben M'Barek. Adhésion et phagocytose de gouttes d'émulsions fonctionnalisées. Chimie analytique. Université Pierre et Marie Curie - Paris VI, 2015. Français. ⟨NNT : 2015PA066034⟩. ⟨tel-01135846⟩



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