TPH1 and systemic lupus erythematosus: Several recent studies on Tph cells have reported their pathological roles in various autoimmune diseases including systemic lupus erythematosus (SLE) (52), (53), (54), primary Sjögren’s syndrome (55), systemic sclerosis (56), type 1 diabetes (57), and inflammatory bowel diseases (58) as well as RA (49), (59), and in malignant tumors (60).