Fig. 2

Tumor-derived exosome (TEX) mediated communication and immunomodulation in the tumor microenvironment (TEX): TEXs transmit immunosuppressive and immunostimulatory signals to immune cells, influencing the immunological response in TME. In terms of immunological suppression, TEXs can cause immune cells like T cells to undergo apoptosis which is required for an efficient immune response against cancer cells. Moreover, TEXs can limit the function of effector T lymphocytes impairing tumor cell killing. TEXs have also been demonstrated to increase macrophage M2 polarization, promoting tumour development and blocking the immunological response to tumors. TEXs can also increase the number of MDSCs, immunological cells that reduce T cell function, further suppressing the anti-tumor immune response. TEXs have also been reported to decrease the development of dendritic cells required for T cell activation and initiating an immunological response. However, TEXs can stimulate the immune system, boost anti-tumor activity and increase the activity of macrophages and NK cells, which play crucial role in destroying cancer cells. TEXs have also been shown to block macrophage M2 polarization which can stimulate an anti-tumor immune response and directly or indirectly boost T cell activation resulting in greater tumor cell death. These immunostimulatory activities of TEXs have the potential to stimulate an effective immune response against cancer and perhaps enhance cancer patient outcomes. Figure created with BioRender.com