FIBCD1 Modulation of the Epithelial Immune Response Elicited by Chitin

Background:
FIBCD1 is a type II transmembrane protein located on the brush border of intestinal epithelial cells. FIBCD1 binds specifically to acetylated compounds
such as chitin through the C-terminal fibrinogen-related domain. Chitin is a highly acetylated homopolymeric b-1,4-N-acetylglucosamine carbohydrate, which next to cellulose is the most abundant biopolymer found in nature, eg in fungi and parasites. It was recently demonstrated that chitin induces the accumulation in tissue of IL-4-expressing innate immune cells in vivo and it was
suggested that chitin thus could be a recognition element implicated in allergic and helminth immunity. However, very little is known about how chitin-induced immune signalling is initiated or propagated.
Aim:
The aim of this project is to investigate the hypothesis that chitin immune signalling may be initiated by the FIBCD1 chitin receptor through activation of
NF-jB signalling and downstream synthesis of mucosal epithelial-derived cytokines, TSLP and IL-33, which shapes the local accumulation and activation of Th2 responses.
Results:
Initial experiments have focused on the establishment of stable FIBCD1 overexpression in HEK293, HCT-116 and A549 epithelial cell lines. Chitin fragments obtained from shrimp shells were produced by brief sonication followed by filtration through 100, 70 and 40 lm filters respectively. Size distribution was determined by fluorescence-activated cell sorting. Cell lines will now be exposed to chitin fragments of varying size or the model ligand acetylated BSA, at different time intervals anddoses and using a luciferase reporter system detection of NFjB activation will be performed and cytokine expression will be quantified via qRT-PCR.
Perspectives:
Improved understanding of epithelialimmune and inflammatory modulation in response to chitin may provide new strategies for therapeutic intervention of allergic or parasitic disease.