Similar as in the case of TLRs, murine NLR knock-out models (Nod2, Nlrp3, Nlrp6, Nlrc4, caspase 1) with increased (albeit partly controversial) susceptibility in different colitis models (183–188) point to NLRs as important host factors for the establishment of a protective gut microbiota. The gene discussed is NOD2; the disease is colitis.