Biology subjects

Settle, A. H.

Publications and source records attributed to Settle, A. H..

3 recordsLinked to original sources

bioRxiv2024

β2 integrins impose a mechanical checkpoint on macrophage phagocytosis

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 and their downstream effectors as critical mediators of this mechanically regulated phagocytic switch. Indeed, comparison of wild type and {beta}2 integrin deficient macrophages indicated that integrin signaling acts as a mechanical checkpoint by shaping filamentous actin to enable distinct phagocytic engulfment strategies. Collectively, these results illuminate the molecular logic of leukocyte mechanosensing and reveal potential avenues for modulating phagocyte function in immunotherapeutic contexts.

cell biology↗

bioRxiv2023

Plasma membrane abundance dictates phagocytic capacity and functional crosstalk in myeloid cells

Professional phagocytes like neutrophils and macrophages tightly control what they eat, how much they eat, and when they move after eating. We show that plasma membrane abundance is a key arbiter of these cellular behaviors. Neutrophils and macrophages lacking the G-protein subunit G{beta}4 exhibit profound plasma membrane expansion due to enhanced production of sphingolipids. This increased membrane allocation dramatically enhances phagocytosis of bacteria, fungus, apoptotic corpses, and cancer cells. G{beta}4 deficient neutrophils are also defective in the normal inhibition of migration following cargo uptake. In G{beta}4 knockout mice, myeloid cells exhibit enhanced phagocytosis of inhaled fungal conidia in the lung but also increased trafficking of engulfed pathogens to other organs. These results reveal an unexpected, biophysical control mechanism lying at the heart of myeloid functional decision-making.

cell biology↗

bioRxiv2023

Topographical analysis of immune cell interactions reveals a biomechanical signature for immune cytolysis

Immune cells live intensely physical lifestyles characterized by structural plasticity, mechanosensitivity, and force exertion. Whether specific immune functions require stereotyped patterns of mechanical output, however, is largely unknown. To address this question, we used super-resolution traction force microscopy to compare cytotoxic T cell immune synapses with contacts formed by other T cell subsets and macrophages. T cell synapses were globally and locally protrusive, which was fundamentally different from the coupled pinching and pulling of macrophage phagocytosis. By spectrally decomposing the force exertion patterns of each cell type, we associated cytotoxicity with compressive strength, local protrusiveness, and the induction of complex, asymmetric interfacial topographies. These features were further validated as cytotoxic drivers by genetic disruption of cytoskeletal regulators, direct imaging of synaptic secretory events, and in silico analysis of interfacial distortion. We conclude that T cell-mediated killing and, by implication, other effector responses are supported by specialized patterns of efferent force.

immunology↗