Sensing of microbial tryptophan catabolites by the aryl hydrocarbon receptor (AhR) plays a pivotal role in host-microbiome homeostasis by modulating the host immune response. Thereby the involved cellular processes triggered by the metabolites are largely unknown. We analyzed proteomic changes in macrophages trough 24h after treatment with the tryptophan metabolites indole-3-acetic acid (I3AA) or indole-3-aldehyde (IAld), as well as the prototypic AhR-ligand Benzo(a)pyrene (BaP) in the absence and presence of LPS to identify affected processes and pathways.