The Clinical Relevance of Periostin in Asthma

Periostin is a matricellular protein which is generated by airway epithelial cells in response to interleukin (IL)-4 and IL-13. Serum periostin levels have been proposed as a biomarker of type-2 inflammation with clinical utility in severe asthma. Normal reference ranges have been established in a predominant Caucasian population using the Elecsys® Periostin immunoassay. Periostin levels do not differentiate asthma from non-asthma, or mild-to-moderate asthma from severe asthma, although they are higher in adults with asthma who have raised levels of blood eosinophils and fractional exhaled nitric oxide (FeNO). Periostin status can predict response to monoclonal antibody therapy directed against IL-13 and immunoglobulin E (IgE), such that adults with severe asthma and a periostin level ≥ 50 ng/ml (designated ”periostin-high”) have a greater therapeutic response than “periostin- low” patients. The clinical relevance of these findings is uncertain, due to the similar predictive ability of the more commonly available biomarkers blood eosinophils and/or FeNO.