IL-4 induces eotaxin in human dermal fibroblasts.

A common feature of Th2-mediated skin diseases is selective eosinophil (Eo) infiltration in the affected dermis. However, the mechanisms of selective Eo recruitment are not yet fully understood. Our recent findings indicated that dermal fibroblasts actively participate in the accumulation of Eo in Th2-mediated skin inflammation. Following stimulation with IL-4, dermal fibroblasts produce eotaxin, which is the only biologically active Eo attractant detected in the supernatants. Natural eotaxin is comprised of a mixture of N-terminal-truncated and O-glycosylated variants. The expression of eotaxin mRNA is upregulated within 1 h after stimulation. TNF-alpha markedly enhances eotaxin mRNA expression and release of the protein product from IL-4-stimulated fibroblasts. As mast cells and Th2 cells produce both cytokines, it is probable that Eo recruitment into sites of allergen-induced, Th2-mediated skin reactions is, at least in part, due to IL-4-stimulated induction of eotaxin in dermal fibroblasts.