Innate immune pattern recognition receptors and associated tumor microenvironment immune cells (PRRs and TME immune cells)

Innate immune pattern recognition receptors (PRRs) are a diverse class of germline-encoded receptors, including Toll-like receptors (TLRs), RIG-I-like receptors (RLRs), and the cGAS-STING pathway, that detect pathogen-associated or damage-associated molecular patterns (DAMPs) (Source: Nature Reviews Cancer, 2019). In the tumor microenvironment (TME), these receptors are expressed on various immune cells such as dendritic cells, macrophages, and myeloid-derived suppressor cells (Source: Frontiers in Immunology, 2020). Activation of PRRs within the TME can shift the immune landscape from an immunosuppressive cold state to an inflamed or hot state by promoting the maturation of antigen-presenting cells and the production of type I interferons and pro-inflammatory cytokines (Source: Journal of Hematology & Oncology, 2021). Consequently, PRRs are major therapeutic targets in immuno-oncology, where agonists are used to enhance the efficacy of checkpoint inhibitors and stimulate a robust anti-tumor T-cell response. However, chronic PRR signaling can also contribute to pro-tumorigenic inflammation, making the context of activation critical for therapeutic success (Source: Cell, 2020).

Other names

Pattern recognition receptorsPRRsInnate immune sensorsInnate immune system receptors

Agonism of PRRs (e.g., TLRs, STING) to stimulate innate immune activation, promote antigen presentation, and enhance T-cell mediated anti-tumor responses; or antagonism to suppress pro-tumorigenic chronic inflammation.