In autoimmune diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), multiple sclerosis (MS), and membranous nephropathy (MN), dysregulation of this axis is characterized by excessive HIF-1α signaling and relative insufficiency of the IDO1/AhR pathway. This evidence concerns the gene IDO1 and systemic lupus erythematosus.