Elevated Levels of β-D-Glucan in Bronchoalveolar Lavage Fluid in Patients with Farmer’s Lung in Miyazaki, Japan

Abstract

Farmers may be often exposed to beta-D-glucan in moldy hay, since straw for feed can be stored throughout the year. The aim of the present study was to clarify whether levels of beta-D-glucan, which modifies immune responses, are high in the respiratory tract in farmer's lung and whether beta-D-glucan participates in the pathogenesis of this condition. We measured beta-D-glucan levels in the bronchoalveolar lavage fluid (BALF) of 10 patients with farmer's lung, 4 with summer-type hypersensitivity pneumonitis (HP) and 10 healthy volunteers. Interleukin (IL)-8 and tumor necrosis factor (TNF)-alpha levels in BALF were measured by enzyme-linked immunosorbent assay (ELISA). We investigated the effects of beta-D-glucan on nuclear factor (NF)-kappaB activation and on the release of IL-8 and TNF-alpha from small airway epithelial cells (SAECs) in vitro. beta-D-Glucan levels in the BALF of farmer's lung patients were increased compared to those in patients with summer-type HP and in healthy volunteers. Additionally, IL-8 levels in BALF were higher in farmer's lung than in summer-type HP, and TNF-alpha levels were equal in the two patient groups but raised compared to those in healthy volunteers. High, but not low, concentrations of beta-D-glucan were found to induce NF-kappaB activation in SAECs. IL-8 levels in the supernatant obtained from SAEC cultures were increased following the addition of beta-D-glucan in vitro. BALF from farmer's lung patients showed high beta-D-glucan levels, which may enhance the expression and release of cytokines through NF-kappaB activation in respiratory epithelial cells.