In patients with IBD, E. coli was found to powerfully upregulate proinflammatory cytokines and chemokines (tumour necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), IL-6, IL-8, IL-17F, IL-23p19, CXCL1 and CXCL2) (13,14). Here, IFNG is linked to irritable bowel syndrome.