In Vitro Studies Toward the Use of Chitin as Nutraceutical: Impact on the Intestinal Epithelium, Macrophages, and Microbiota

SCOPE: Chitin, the most abundant polysaccharide found in nature after cellulose, is known for its ability to support wound healing and to lower plasma‐oxidized low‐density lipoprotein (LDL) levels. Studies have also revealed immunomodulatory potential but contradicting results are often impossible to coalesce through usage of chitin of different or unknown physicochemical consistency. In addition, only a limited set of cellular models have been used to test the bioactivity of chitin. METHODS AND RESULTS: Chitin is investigated with well‐defined physicochemical consistency for its immunomodulatory potency using THP‐1 macrophages, impact on intestinal epithelial barrier using Caco‐2 cells, and fermentation by fecal‐derived microbiota. Results show that chitin with a degree of acetylation (DA) of ≈83%, regardless of size, does not affect the intestinal epithelial barrier integrity. Large‐sized chitin significantly increases acetic acid production by gut microbiota without altering the composition. Exposure of small‐sized chitin to THP‐1 macrophages lead to significantly increased secretion of IL‐1β, IL‐8, IL‐10, and CXCL10 in a multi‐receptor and clathrin‐mediated endocytosis dependent manner. CONCLUSIONS: These findings indicate that small‐sized chitin does not harm the intestinal barrier nor affects SCFA secretion and microbiota composition, but does impact immune activity which could be beneficial to subjects in need of immune support or activation.