Microenvironmental and Structural Regulation of Membrane Trafficking in Immune cells

Abstract

This study focuses on the microenvironmental and structural regulation of membrane trafficking in immune cells. Membrane trafficking was addressed in two distinct immune contexts, but from independent perspectives. First, macrophage trafficking in the ovarian cancer tumor microenvironment was examined, where macrophages constitute the innate arm of the immune system. Second, from a biophysical perspective, the effects of perturbations in the actin cytoskeleton and membrane organization on trafficking dynamics of cytotoxic granules in CD8⁺ T cells (CTLs) were investigated, as CTLs represent the adaptive arm of the immune system. It was found that macrophage fluid-phase uptake was altered when cells were treated with malignant ascites, whereas their exocytosis dynamics remained unchanged. In CTLs, actin cytoskeletal perturbation had minimal effect on granule motility, whereas cholesterol perturbation, especially depleting cholesterol from the cell membrane, resulted in altered granule motility and more confined behavior. A functional assay was performed to assess degranulation efficiency under cholesterol perturbation, revealing that degranulation was unaffected. Interestingly, these results showed that granule motility and degranulation can occur independently of each other. Together, these findings suggest that immune cell trafficking could be regulated at multiple levels, and perturbations of a single component can have distinct effects at different stages of the same process.