Fig. 2

Mechanisms of AhR activation by microbiome in the tumor microenvironment. The microbiome within the tumor microenvironment secretes a variety of metabolites, including SCFAs, formate, and tryptophan-derive indoles, which promote immune tolerance and metastasis through activation of the AhR pathway. Furthermore, the release of TNF-⍺ and IL-6 in response to LPS in tumor-associated macrophages and dendritic cells (antigen-presenting cells; APCs) upregulates IDO activity in the resident APCs and tumor cells, leading to local overproduction of Kyn from tryptophan, which activates AhR to further promote immune tolerance. Created with BioRender.com