Abstract
Phagocytosis is an intensely physical process that depends on the mechanical properties of both the phagocytic cell and its chosen target. Here, we employed differentially deformable hydrogel microparticles to examine the role of cargo rigidity in the regulation of phagocytosis by macrophages. Whereas stiff cargos elicited canonical phagocytic cup formation and rapid engulfment, soft cargos induced an architecturally distinct response, characterized by filamentous actin protrusions at the center of the contact site, slower cup advancement, and frequent phagocytic stalling. Using phosphoproteomics, we identified beta 2 integrins as critical mediators of this mechanically regulated phagocytic switch. Macrophages lacking beta 2 integrins or their downstream effectors, Talin1 and Vinculin, exhibited specific defects in phagocytic cup architecture and selective suppression of stiff cargo uptake. We conclude that integrin signaling serves as a mechanical checkpoint during phagocytosis to pair cargo rigidity to the appropriate mode of engulfment.
Phagocytosis is regulated by the mechanical properties of both the phagocyte and its cargo. Here, the authors show that macrophages employ beta 2 integrins to sense the rigidity of phagocytic cargo and then mount the appropriate form of engulfment.