MUC5AC and colitis: IL-18 has been proposed to help maintain a healthy gut microbiota and to protect from colitis likely involving induction of mucin production.60, 61, 62, 63 However, while IL-18 increases in serum during KD, systemic IL-18R1 (also known as IL-18Rα or IL-1R-related protein (IL-1Rrp)), its essential receptor,64 decreases significantly.