Nanoparticles that modulate immune cells - an important strategy for the future treatment of tumors.

Cancer has become a major public health issue that seriously threatens human health. With the widespread development and application of drug-loaded nanosystems in tumor therapy, numerous studies have confirmed that various nanoparticles can exert anti-tumor activity by regulating one or more immune cells in the tumor microenvironment (TME), including depleting M2-type TAMs in the TME, limiting the recruitment and localization of TAMs, reprogramming M2-type TAMs into M1-type TAMs, enhancing NK cells homing or function, promoting DCs maturation, inhibiting TANs recruitment or altering their polarity, reducing circulating and tumor-infiltrating MDSCs, altering MDSCs phenotype or inhibiting MDSCs functions (including nanocapsules, metal-organic frameworks, micelles, polymers, dendritic macromolecules, liposomes, and other material nanoparticles), promoting CD8+ T cells proliferation or activity and reducing the number of Tregs (including nanoparticles composed of liposomes, gels, cerium, and selenium, hyaluronic acid-modified nanoparticles, nanocapsules, nanovesicles, other material nanoparticles, and nanoparticles combined with other treatment modalities), besides, some nanoparticles can exert anti-tumor activity by regulating two or more types of immune cells in the TME. In short, nanoparticles targeting immune cells will become an important strategy in tumor treatment based on the advantages of nanoparticles in enhancing efficacy and reducing toxicity in tumor therapy, as well as the important role of immune cells in tumor occurrence and development. In this article, we will provide a detailed introduction to nanoparticles that exert anti-tumor activity by regulating immune cells in the TME and briefly introduce the mechanisms by which nanoparticles regulate immune cells.