Transforming growth factor‐β in allergic inflammatory disease of the upper airways: friend or foe?

Summary TGF‐β is a multi‐functional cytokine with a huge array of effects on a variety of cell types. It is rapidly emerging as a key major player in the way the airway epithelium behaves and its ability to repair itself. This is not only of relevance to allergic airway diseases such as asthma and allergic rhinitis, which are increasing in prevalence worldwide, but in many other diseases. The full impact any disruption of TGF‐β signalling may have in the development and persistence of allergic inflammatory airway diseases is yet to be fully realized and remains the subject of ongoing research. There has been a recent revival of interest in the role of regulatory T cells in controlling allergic inflammation. Evidence is emerging of a significant contribution by TGF‐β to this regulatory process. This review aims to summarize current knowledge relating to TGF‐β in relation to allergic inflammatory upper airways disease, and attempts to clarify some of the discrepancies and inconsistencies in this area. It also considers the therapeutic implications of novel TGF‐β therapy, including potential future applications in the treatment of nasal polyposis and reduction of post‐operative scar tissue formation following endoscopic sinus surgery.