TNF and colitis: In animal models of colitis, GLP-2 acts via vasoactive intestinal polypeptide (VIP) neurons in the submucosal plexus to reduce pro-inflammatory cytokines, such as TNF-α and interferon-γ (IFN-γ), and mitigate mucosal injury by increasing crypt cell proliferation, upregulating suppressor of cytokine signaling 3 expression, and reducing signal transducer and activator of transcription 3 signaling, crypt cell apoptosis, and IGF-1 production [195,196,197,198,199,200].