Natural Plant Products Mediated Prevention of Cancer Facilitated through Immune Suppression of Treg Cells

Cancer is one of the leading causes of death, and numerous methods have been tested and used to figure out an optimum way of treatment. Besides targeted therapy, immunotherapy has proven to be effective by controlling certain immune cells. Traditional cancer therapy is met with the consequences of adverse side effects that have been a major issue for treatment; hence, a leap towards naturally occurring immunomodulators was taken to develop safer methods of treatment. One of the major immune cells responsible for the growth of tumors is regulatory T cells (Tregs). To maintain immunological homeostasis, Treg dampens abnormal immune responses to self and non-self-antigens. The transcription factor FoxP3 is responsible for their lineage specification and takes part in the production of immunosuppressive cytokines like IL10, IL35, and TGFb. This helps cancer cells to proliferate without the restriction of different immune cells like CD8⁺T cells, dendritic cells, monocytes/macrophages, B cells, and natural killer cells. Hence, targeting Tregs to provide unhindered immunosurveillance has proven to be a breakthrough in cancer immunotherapy. This review mainly focuses on some common naturally occurring immunomodulators derived from plant products that have earned their place as immunotherapeutic agents, along with some of their ability to suppress Tregs that can be used as an effective way to treat cancer.