Periostin, a matrix protein, is a novel biomarker for idiopathic interstitial pneumonias

Rationale : The evidences of serum biomarker for the diagnosis and the prediction of clinical outcome in Idiopathic interstitial pneumonias (IIPs) were not enough. Objectives : In this study, we addressed whether periostin, a matrix protein, could be a biomarker of IIPs. Patients and Methods : We established the rat anti-human periostin monoclonal antibody and performed immunohistochemical analyses in each histopathological type of IIPs including IPF/UIP, fibrotic and cellular (f and c) NSIP and COP. We examined serum levels of periostin in IIPs patients by ELISA and analyzed the relationship between serum levels of periostin and the pulmonary functions in patients with IPF. Result : The lung tissues of UIP showed strongly expression of periostin in fibroblasts,especially in fibroblastic foci areas, which appeared to be normal lung tissues, but not in areas showing established fibrosis or inflammatory cells. In fNSIP, periostin was also strongly expressed in fibroblasts, but not inflammatory cells. In the lung tissues of cNSIP and COP, periostin was scarcely observed. Serum periostin levels in IPF patients were significantly elevated (n=37; 107.1±11.9 ng/mL) compared to those in COP patients (n=9; 58.9±8.2 ng/mL, P<0.01) and control subjects (n=66; 39.1±3.0 ng/mL, P<0.0001). Those of fNSIP were moderate (n=7; 77.9±15.7 ng/mL) and statistically different to control subjects (P<0.01), but not to COP patients. The serum periostin level was well correlated with decline of vital capacity during a 6-month period. Conclusion : We have found that periostin is a novel component of fibrosis in IIPs and is a useful biomarker to define the histopathological types in IIPs and assess pulmonary function in IPF/UIP.