IL-17 cytokine/receptor families: emerging targets for the modulation of inflammatory responses

Abstract

IL-17 was identified a decade ago as a pro-inflammatory cytokine produced by activated T cells that stimulates the secretion of other cytokines from various non-lymphoid cells by acting through a unique cell surface receptor, IL17R. Evidence that IL-17 may contribute to several immune-mediated diseases, such as rheumatoid arthritis and airway inflammation, prompted much interest in this cytokine. Recently, the large-scale analysis of expressed sequence tags (EST) led to the discovery of novel genes dispersed in the human genome that encode at least five additional cytokines structurally related to IL-17. Screening of EST databases also uncovered at least four novel genes encoding Type I transmembrane proteins with significant homology to IL-17R, thereby forming a family of receptors whose cognate ligands are likely to belong to the IL-17 cytokine family. Initial characterisation of some of these cytokines and one IL-17R homologue demonstrated their involvement in regulating inflammatory responses in a manner similar to, albeit distinct from, that of prototypic IL-17. The IL-17 cytokine/receptor families appear therefore to represent unique signalling systems within the cytokine network that might offer innovative approaches to manipulate immune and inflammatory responses. The prospect of targeting these molecules for therapeutic purposes has generated a substantial volume of patent literature that will be reviewed here.

• airway inflammation
• asthma
• cytokines
• graft rejection
• IL-17 cytokine family
• IL
• 17
• receptor family
• immunoregulation
• rheumatoid arthritis
• T cell