Chitin, Chitinases and Chitinase-like Proteins in Allergic Inflammation and Tissue Remodeling

Abstract

Chitin, the second most abundant polysaccharide in nature after cellulose, consist exoskeleton of lower organisms such as fungi, crustaceans and insects except mammals. Recently, several studies evaluated immunologic effects of chitin in vivo and in vitro and revealed new aspects of chitin regulation of innate and adaptive immune responses. It has been shown that exogenous chitin activates macrophages and other innate immune cells and also modulates adaptive type 2 allergic inflammation. These studies further demonstrate that chitin stimulate macrophages by interacting with different cell surface receptors such as macrophage mannose receptor, toll-like receptor 2 (TLR-2), C-type lectin receptor Dectin-1, and leukotriene B4 recepptor (BLT1). On the other hand, a number of chitinase or chitinase-like proteins (C/CLP) are ubiquitously expressed in the airways and intestinal tracts from insects to mammals. In general, these chitinase family proteins confer protective functions to the host against exogenous chitin-containing pathogens. However, substantial body of recent studies also set light on new roles of C/CLP in the development and progression of allergic inflammation and tissue remodeling. In this review, recent findings on the role of chitin and C/CLP in allergic inflammation and tissue remodeling will be highlighted and controversial and unsolved issues in this field of studies will be discussed.

Host-defence-related proteins in cows’ milk

“…CG39 was first described in synovial fluid, but it is also found in certain immune cells as well as mammary secretions in the dry period (Rejman and Hurley, 1988;Hakala et al, 1993). The expression of CG39 has been reported to be elevated in inflamed tissues in a range of chronic inflammatory conditions such as arthritis, inflammatory bowel disease, asthma and allergy (Elias et al, 2005;Bigg et al, 2006;Lee, 2009). The amino acid sequence and three-dimensional structure of human and bovine CG39 are similar to members of the chitinase family of host-defence proteins found predominantly in plants.…”

Chitin and carbon nanotube composites as biocompatible scaffolds for neuron growth

“…Chitin and its derivatives has previously been shown to have a protective effect on neurons in the early stage nerve injury 31 32 . There is also evidence suggesting that chitin could negatively modulate Type 2 immune responses 33 . Accelerated nerve regeneration using induced pluripotent stem cells in chitin-chitosan-gelatine scaffolds with inverted colloidal crystal geometry has been observed 34 .…”

Strategies of mucosal immunotherapy for allergic diseases

“…There are still many controversial and unsolved issues in this field to be discussed. 74 Chitosan is formed naturally through the action of chitin deacetylases or by the deacetylation of chitin oligosaccharides. 75 It is a natural biodegradable mucoadhesive polysaccharide derived from crustacean shells.…”