Macrophages are key innate immune cells that clear pathogens through phagocytosis and micropinocytosis(Mylvaganam et al.,2021).While actinbased protrusions such as filopodia and lamellipodia have been well studied as ...Macrophages are key innate immune cells that clear pathogens through phagocytosis and micropinocytosis(Mylvaganam et al.,2021).While actinbased protrusions such as filopodia and lamellipodia have been well studied as typical substructures in macrophages to capture pathogens(Blake and Gallop,2023;Pratiwi et al.,2024),their effectiveness against massive bacterial onslaughts is limited.Gramnegative bacteria.展开更多
Phagocytosis of opsonized pathogens by circulating non-adherent neutrophils is an essential step in host defense, which when overwhelmed contributes to sepsis. To investigate the role played by ligation of complement ...Phagocytosis of opsonized pathogens by circulating non-adherent neutrophils is an essential step in host defense, which when overwhelmed contributes to sepsis. To investigate the role played by ligation of complement receptors CR3 and CR4 in non-adherent neutrophils, we designed a novel assay system utilizing dual optical traps, respectively, holding a suspended unactivated cell and presenting a specific ligand-coated bead to the cell surface. We chose anti-CD 18 as an example ligand, mimicking the bacterial opsonizing complement fragment iC3b. Presentation of anti-CD 18-coated beads elicited both pseudopodial protrusion and subsequent phagocytosis. This is in sharp contrast to previously reported responses of adherent neutrophils, which phagocytize opsonized particles without pseudopod formation. We used this same new assay to probe actomyosin pathways in the neutrophil＇s pseudopodial and phagocytic response. Disruption of actin or inhibition of myosin light-chain kinase dose-dependently reduced pseudopod formation and phagocytosis rates. In summary, i） the new dual trap assay can be used to study the responses of suspended neutrophils to a variety of ligands, and ii） in a first application of this technique, we found that local ligation of CR3/4 in unactivated neutrophils in suspension induces pseudopod formation and phagocytosis at that site, and that these events occur via an actomyosindependent pathway.展开更多
基金supported by grants from the National Key R&D Program of China(2022YFC2303500 and 2024YFC2310003)the National Natural Science Foundation of China(32222022 and 92354301)+1 种基金R&D Program of Guangzhou National Laboratory(GZNL2023A03004)Natural Science Foundation of Shanghai(23ZR1470900)to Y.J.
文摘Macrophages are key innate immune cells that clear pathogens through phagocytosis and micropinocytosis(Mylvaganam et al.,2021).While actinbased protrusions such as filopodia and lamellipodia have been well studied as typical substructures in macrophages to capture pathogens(Blake and Gallop,2023;Pratiwi et al.,2024),their effectiveness against massive bacterial onslaughts is limited.Gramnegative bacteria.
文摘Phagocytosis of opsonized pathogens by circulating non-adherent neutrophils is an essential step in host defense, which when overwhelmed contributes to sepsis. To investigate the role played by ligation of complement receptors CR3 and CR4 in non-adherent neutrophils, we designed a novel assay system utilizing dual optical traps, respectively, holding a suspended unactivated cell and presenting a specific ligand-coated bead to the cell surface. We chose anti-CD 18 as an example ligand, mimicking the bacterial opsonizing complement fragment iC3b. Presentation of anti-CD 18-coated beads elicited both pseudopodial protrusion and subsequent phagocytosis. This is in sharp contrast to previously reported responses of adherent neutrophils, which phagocytize opsonized particles without pseudopod formation. We used this same new assay to probe actomyosin pathways in the neutrophil＇s pseudopodial and phagocytic response. Disruption of actin or inhibition of myosin light-chain kinase dose-dependently reduced pseudopod formation and phagocytosis rates. In summary, i） the new dual trap assay can be used to study the responses of suspended neutrophils to a variety of ligands, and ii） in a first application of this technique, we found that local ligation of CR3/4 in unactivated neutrophils in suspension induces pseudopod formation and phagocytosis at that site, and that these events occur via an actomyosindependent pathway.
