IL22RA1 and colitis: 24 Also, IL-22Ra1 signaling in the Paneth cells induces antimicrobial peptide production, such as cryptidin, Reg3γ, and Reg3β.24–28 In addition, we and others have shown that IL-22 promotes Paneth cell differentiation.24,29 Paneth cells are absent in the mouse colon; however, their antimicrobial products (cryptidin, lysozyme, etc.)traverse to the colon lumen.30,31 It has been reported that Paneth-like cells have been found in the colon.32 It is not known if IL-22Ra1 signaling in the Paneth cells can affect the mucosal barrier in the colon and protect it from DSS-induced colitis development.