AHR and infection: Consistent with decreased ILC3 numbers, mice fed on a AhR ligand-free synthetic diet express lower levels in the intestine of antimicrobial peptides such as C-type lectin regenerating islet-derived protein 3 (RegIII) (29, 34), and are more susceptible to infections with Citrobacter Rodentium (35) or Clostridium difficile (28).