Corroborating this notion, the human orthologues of SerpinA3N, α-1-antitrypsin (SERPINA1) and α-1-antichymotrypsin (SERPINA3) are increased in serum and faeces from IBD patients.39–41 These previous studies have focused on total protein levels and not the actual activity of NE. This evidence concerns the gene SERPINA1 and inflammatory bowel disease.