These results build on a previous study indicating that AhR ligands can also signal via astrocytes, and that AhR signaling may form part of the protective influence of interferon-beta in MS.105 Thus, microbial tryptophan metabolism and AhR ligands are a promising lead for harnessing endogenous microglia-microbial signaling pathways in MS, and efforts to validate their role in human subjects are ongoing.106. Here, AHR is linked to myeloid sarcoma.