The pro‐inflammatory cytokines IL‐1β36 and TNF‐α,37 the receptor TLR9 sensing unmethylated CpG dinucleotides of microbial DNA,38 the antibacterial enzyme lysozyme39 and transcription factors for type 1 interferons IRF5 and IRF738 reflect activation of the immune response and were all expressed to a higher degree in IBS patients. This evidence concerns the gene TNF and irritable bowel syndrome.