Role of trained innate immunity against mucosal cancer

Abstract

Mucosal tissues are frequent targets of both primary and metastatic cancers. This has highlighted the significance of both innate and adaptive anti-cancer immunity at mucosal sites. Trained innate immunity (TII) is an emerging concept defined as enhanced reactivity of innate leukocytes long after a previous stimulation that induces prolonged epigenetic, transcriptional, and metabolic changes. Trained innate leukocytes can respond to heterologous targets due to their lacking of antigen-specificity in most cases. Emerging experimental and clinical data suggest that certain microbes or their products induce TII in mucosal-associated innate leukocytes which endows heterologous anti-tumor innate immunity, in both prophylactic and therapeutic scenarios. In this mini-review, we summarize updated findings on the significance of TII in mucosal cancers. We also attempt to raise a few key questions critical to our further understanding on the roles of TII in mucosal cancers, and to the potential application of TII as anti-cancer strategy.