Pearls Innate Sensing of

Chitin is the second most common polysaccharide found in nature. It is present in crustacean shells, insect exoskeletons, parasitic nematode eggs and gut linings, and in the cell wall of fungi. The deacetylated derivative of chitin, chitosan, is less common but is particularly evident in certain species of fungi, such as Cryptococcus, and the cyst wall of Entamoeba. How mammals sense and respond to these polymers is not well understood, and conflicting reports on their immunological activity have led to some controversy. Despite this, promising translational applica-tions that exploit the unique properties of chitin and chitosan are being developed. What Are Chitin and Chitosan? Chitin, a linear, neutrally charged polymer of b-(1,4)-linked N-acetylglucosamine (GlcNAc), and its deacetylated derivative chitosan, a cationic polymer of glucosamine (GlcN), are tw