Carbon Nanomaterials: Emerging Roles in Immuno-Oncology

Abstract

Cancer immunotherapy has made breakthrough progress in cancer treatment. However, only a subset of patients benefits from immunotherapy. Given their unique structure, composition, and interactions with the immune system, carbon nanomaterials have recently attracted tremendous interest in their roles as modulators of antitumor immunity. Here, we focused on the latest advances in the immunological effects of carbon nanomaterials. We also reviewed the current preclinical applications of these materials in cancer therapy. Finally, we discussed the challenges to be overcome before the full potential of carbon nanomaterials can be utilized in cancer therapies to ultimately improve patient outcomes.

Keywords: cancer; carbon nanomaterials; immunotherapy.

Figure 1

Schematic representation of the immunomodulatory effects of CNMs in cancer therapy. CNMs enhance antitumor immunity through multiple and diverse mechanisms of immune modulation. Antigen-presenting cells (APCs), namely dendritic cells (DCs), pick up the CNM–antigen conjugate and transfer the antigen peptides to naive T cells for activation. A multitude of unique receptors on the surface of DCs serve as natural recognition sites for activating certain immune cells. Nevertheless, targeting DCs alone is insufficient to elicit a significant immunological response. The movement of antigens to particular compartments for presentation in DCs is critical. In DCs, for example, the lysosome-dependent route leads to the antigen breaking down into antigenic peptides within the lysosomes, which are then loaded onto Class II major histocompatibility complex (MHC-II) molecules for presentation to CD4+ helper T cells. MHC-I molecules, on the other hand, display cytosolic antigens to activate CD8+ T cells and trigger cytotoxic T lymphocyte (CTL) responses [45]. Other cytokines, such as TNF- α, send chemical signals to the tumor, causing inflammation and cell death [46]. IFN-γ is largely released by activated T cells and natural killer (NK) cells, and has the ability to activate macrophages and improve antigen presentation [47]. Many cytokines, notably IL-15 and IL-12, can activate and stimulate proliferation and expansion the of NK cells, as well as other antitumor immune cells, including CD8+ T cells [48].