As reported previously,12 CR-Kp reached high densities in the intestine (Figure 1b), without inducing signs of overt inflammation, consistent with the notion that most Kp isolates are avirulent in the gut lumen (data not shown).21 One week following reconstitution, we injected animals i.p. with anti-CD3 antibody, which activates T cells producing a systemic cytokine storm and local activation in the intestinal tissue.36,37 This model has been widely employed to recapitulate GVHD-induced diarrhea and promotes short-lasting responses and self-limited sickness in the animals36–39. Here, NPPA is linked to graft versus host disease.