Elevated levels of periostin and TGF-₁ in the bronchoalveolar lavage fluid of patients with idiopathic eosinophilic pneumonia

Background: Periostin is induced in bronchial epithelial cells and fibroblasts by various stimuli including interleukin (IL)-13 and transforming growth factor (TGF)-beta(1), and is involved in allergic diseases such as asthma and atopic dermatitis, playing an important role in tissue remodeling and fibrosis. The role of periostin in the pathogenesis of cosinophilic lung diseases, however, is unclear. Objective: To examine the contribution of periostin to cosinophilic inflammation of the lung in humans, we evaluated periostin, IL-13, and TGF-beta(1) levels in the bronchoalveolar lavage fluid (BALF) of patients with cosinophilic pneumonia (EP). Methods: Periostin, IL-13, and TGF-beta(1) concentrations in the BALF were measured by enzyme-linked immunosorbent assay in patients with acute EP, chronic EP, idiopathic pulmonary fibrosis (IPF), and sarcoidosis. Further, we analyzed the relationship between periostin, IL-13, and TGF-beta(1), levels and the number of inflammatory cells in the BALE. Results: The absolute number ofeosinophils, and the periostin, IL-13, and TGF-beta(1) levels in the BALF were significantly higher in patients with EP than in patients with IPF and sarcoidosis. Concentrations of periostin significantly correlated with the concentrations of TGF-beta(1), but not those of IL-13, in the BALF of patients with EP. Periostin levels also significantly correlated with the absolute number of cosinophils in the BALF of patients with IPF, but not EP. Conclusions: Our findings suggest that TGF-beta(1) might increase the production of periostin in the lungs of patients with EP. Periostin might contribute the pathogenesis of not only EP, but also IPE.