Of note, the ligands of AHR can be divided into host-derived kynurenine-based ligands, which are upregulated and detrimental after stroke with worsened microglia survival as well as poor prognosis, and microbiota-derived indole-based ligands, such as IAld and IPA, which decrease especially within the first 24 h in both the plasma and the brain after stroke, along with significant reductions in major bacterial populations involved in the regulation of Trp-derived ligands, such as Bifidobacteriales and Lactobacillales [190]. The gene discussed is AHR; the disease is Stroke.