NFKB1 and multiple sclerosis: The AHR is a ligand-dependent transcription factor expressed by epithelial cells, immune cells, microglia, and astrocytes.247,248,425 Previous studies on multiple sclerosis mouse models have demonstrated that the AHR acts as a negative regulator of NF-κB activation, and the specific deletions of Ahr in astrocytes and microglia resulted in CNS inflammation and neurodegeneration.247,248