Chitin and its derivatives as potential candidates to reduce intestinal colonization of Crohn’s disease-associated adherent and invasive E. <i>coli</i>

Crohn's disease (CD) is a chronic inflammatory bowel disease becoming a major issue for healthcare systems in most parts of the world. While the causes of the disease are still not fully understood, the role of the microbiota has been widely demonstrated including the colonization by a particular pathovar of <i>Escherichia coli</i>, defined as adherent and invasive E. <i>coli</i> (AIEC), able to adhere to, and invade the intestinal epithelium, as well as to survive within macrophages. As the involvement of AIEC within CD pathophysiology is highly suspected, developing new strategies to limit AIEC colonization is a promising area of research. In this context, chitin and its derivatives, such as chitosan and chito-oligosaccharides (COS), possessing immunomodulatory and antimicrobial properties, could be promising candidates. This review provides a structural overview of chitin and its derivatives and summarizes the existing literature in the context of the potential beneficial effects of chitinous elements in CD and CD-like models, their capability to restrict AIEC colonization <i>via</i> multiple mechanisms, such as of reducing AIEC growth, countering biofilm formation, blocking bacterial adhesion, or stimulating the innate immune response. Lastly, we will explore strategies based on chitin-supplemented diet as therapeutic strategy in patients with CD.