3.2. The roles of lamellipodia and filopodia in immune cells’ activity during malignancy
Lamellipodia and filopodia on macrophages and T cells play crucial roles in malignancy, largely due to their involvement in cell movement, environmental sensing, and immune responses. Macrophage filopodia assist in the phagocytic uptake of particles, aiding in pathogen clearance. They capture pathogens by various mechanisms, including surfing along the filopodial shaft towards the cell body and sweeping actions. These mechanisms are crucial for the phagocytic uptake of particles and, by extension, plays a significant role in tumor immunity where phagocytosis of cancer cells is involved [33]. In T cells, lamellipodia and filopodia play a crucial role in crossing endothelial barriers, a process vital during immune surveillance and inflammation. Rho GTPases, which regulate cytoskeletal dynamics, are essential for T-cell polarization and migration [34]. A study by Doh, Song, and Kwon (2013) found that T cells utilize lamellipodia to sense topography of endothelial cell layers and filopodia to sense nuclei of endothelial cells, crucial for optimal intraluminal path finding during transendothelial migration [35]. Ward (2009) described shear-facilitated chemokine-induced adhesive filopodia on crawling T lymphocytes that scan the endothelial surface for potential sites of transendothelial migration, indicating a novel mode of lymphocyte locomotion over endothelial cells before extravasation [36]. Shulman et al. (2009) found that endothelial-presented chemokines triggered high-affinity lymphocyte function-associated antigen 1 (LFA-1) and adhesive filopodia underneath crawling lymphocytes, which were critical for lymphocyte crawling and probing for transendothelial migration sites [37].