Gut microbiota modulate host immune cells in cancer development and growth

Abstract

Emerging evidence shows that microbe interactions with the host immune system impact diverse aspects of cancer development and treatment. As a result, exciting new opportunities exist for engineering diets and microbe cocktails to lower cancer risks with fewer adverse clinical effects than traditional strategies. Microbe-based therapies may ultimately be used to reinforce host immune balance and extinguish cancer for generations to come.

Keywords: Bacteria; Health; Homeostasis; Hygiene; Lymphocyte; Neutrophil; Thymus.

Fig. 1. Gut microbiota interact with whole body physiology to promote or undermine good health

Bacteria in the gastrointestinal (GI) tract influence a gut-immune-endocrine system axis. Microbial symbiosis promotes an overall homeostatic balance by oxytocin and thymus gland dominant immune functions, with balanced effector and suppressive immunity culminating in good health. By contrast, gut dysbiosis, anxiety and stress contribute to corticosterone-biased undermining of thymus gland functions, promoting a smoldering pro-inflammatory systemic tone with high levels of neutrophils and increased risk of developing cancer.

Fig. 2. Bacteria from the environment interface with mammalian biology via vast mucosal surfaces of the GI tract

Gut epithelial cells and antigen-presenting cells comprise the initial interactions with GI tract bacteria. Innate and adaptive immune cells amplify signaling to eliminate pathogens and stimulate tissue repairs. Subsequently, Interleukin-10 and regulatory T (Treg) cell subsets enforce local homeostasis to minimize collateral tissue damage. Rapid return to homeostasis stabilizes epithelial barriers to reduce translocation of bacteria [sepsis] and restore lower systemic inflammatory tone. Infiltrating neutrophil precursors are important mediators of cancer. Shown are neutrophil precursor cells (arrow) in the stroma of mouse mammary cancer. Bar=25 μm.