P2X7-/- mice with ileitis presented an increased relative abundance of the Cyanobacteria phylum, specifically the Gastranaerophilales order, in addition to an increase in the Bacteroidales order (Bacteroidetes phylum) and Lachnospiraceae family (Firmicutes phylum), compared to knockout uninfected mice. Here, P2RX7 is linked to Crohn ileitis.