CST4 and inflammatory bowel disease: A large amount of relevant studies involving experimental infection with helminth or treatment with parasite-derived components have proven to work wonders in practical applications of diverse animal experimental models or human experience, such as ingesting infectious Trichuris suis eggs for IBD, using filarial cystatin or products of Ancylostoma ceylanicum against collagen-induced arthritis, or taking hookworm protein for asthma therapy [59–62].