Bacteria modulate tumor-associated macrophages to combat cancer

Tumor microenvironment (TME) is a manipulator of tumorigenesis and development, which consists of tumor cells, immune cells, fibroblasts, intercellular stroma, microvasculature, and a variety of biomolecules. Bacteria and tumor-associated macrophages (TAMs) are essential elements of the TME. TAMs and bacteria can be altered and recruited by tumor cells, and the interaction between controlled bacteria and TAMs accelerates tumor progression. Reshaping the TME by regulating macrophages through intratumoral bacteria may be a new anti-tumor strategy. However, the mechanisms underlying bacterial-macrophage interactions and how bacteria regulate macrophages to combat tumors remain poorly understood. This review summarizes the relationships among bacteria, macrophages, and tumors within the tumor microenvironment, as well as recent advances in bacteria-targeted regulation of macrophage antitumor activity.