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. Author manuscript; available in PMC: 2009 Dec 1.
Published in final edited form as: Curr Opin Immunol. 2008 Nov 1;20(6):684–689. doi: 10.1016/j.coi.2008.10.002

Figure 2.

Figure 2

Schematic illustrating the proposed roles of chitin size in anti-pathogen responses. . Chitin containing pathogens contain large chitin polymers that are felt to be biologically inert. The antiparasite response causes chitin fragmentation. The larger fragments (termed intermediate chitin) interact with a variety of macrophage receptor systems including, the macrophage mannose receptor and TLR-2 to produce a variety of proinflammatory cytokines and mediators including IL-17, IL-23, TNF and LTB4. The resulting inflammatory response can, in turn, stimulate the production of C/CLP. This includes AMCase which can further degrade the chitin polymers. This results in the accumulation of even smaller molecules (termed small chitin) which can induce the production of the anti-inflammatory cytokine IL-10 via Dectin -1. It also includes BRP-39/YKL-40 which can control inflammatory cell death. In an appropriately regulated response, the anti-inflammatory effects of molecules like IL-10 and the degradation of chitin to smaller saccharides (for example; di-saccharides and mono-saccharides) likely contribute to the resolution of the response once the pathogen has been controlled.