Abstract:

The aim of this study was to explore and evaluate the effects of insulin-like growth factor-1 (IGF-1), an important bioactive material in bovine colostrum, on the production levels of IFN-γ, TNF-α, TGF-β1, IL-1β, IL-10, IL-4, IL-6, and IL-1Ra in rabbit serum and to study the regulatory effects of IGF-1 on the gastrointestinal mucosa immunity signaling. Rabbit serum was collected 3 , 2, and 2 h after oral administration, intraperitoneal injection and ear intravenous injection with IGF-1, respectively, to examine the contents of IFN-γ, TNF-α, TGF-β1, IL-1β, IL-10, IL-4, IL-6, and IL-1Ra by ELISA assay. The IGF-1 administration in the three ways all significantly increased the contents of inflammatory cytikines like IFN-γ, IL-6, IL-1, and TNF-α while the contents of anti-inflammatory cytokines like TGF-β1, IL-10, IL-4, and IL-1Ra were significantly decreased. After entering the intestine, IGF-I as a foreign antigen is processed and presented by intestinal epithelial cells, dendritic cells and other antigen-presenting cells to activate intracellular inflammatory signaling pathway. A part of IGF-1 that is not digested in the gastrointestinal tract is likely to be absorbed by a polycation-sensitive, absorptive-mediated endocytosis and was identified by macrophages, monocytes, mast cells, NK cells and other innate immune cells and thus induces the production of inflammatory cytokines and inhibit the production of anti-inflammatory cytokines.

Key words: insulin-like growth factor-1, gastrointestinal mucosa immunity system, cytokine