Th17 can regulate silica‐induced lung inflammation through an IL‐1β‐dependent mechanism

Abstract

Silicosis is an occupational lung disease caused by the inhalation of silica dust and characterized by lung inflammation and fibrosis. Interleukin (IL)-1β is induced by silica and functions as the key pro-inflammatory cytokine in this process. The Th17 response, which is induced by IL-1β, has been reported very important in chronic human lung inflammatory diseases. To elucidate the underlying mechanisms of IL-1β and IL-17 in silicosis, we used anakinra and an anti-IL-17 monoclonal antibody (mAb) to block the receptor of IL-1β (IL-RI) and IL-17, respectively, in a mouse model of silicosis. We observed increased IL-1β expression and an enhanced Th17 response after silica instillation. Treatment with an IL-1 type I receptor (IL-1RI) antagonist anakinra substantially decreased silica-induced lung inflammation and the Th17 response. Lung inflammation and the accumulation of inflammatory cells were attenuated in the IL-17-neutralized silicosis group. IL-17 may promote lung inflammation by modulating the differentiation of Th1 and regulatory T cells (Tregs) and by regulating the production of IL-22 and IL-1β during the lung inflammation of silicosis. Silica may induce IL-1β production from alveolar macrophages and promote inflammation by initiating a Th17 response via an IL-1β/IL-1RI-dependent mechanism. The Th17 response could induce lung inflammation during the pathogenesis of silicosis by regulating the homoeostasis of the Th immune responses and affecting the production of IL-22 and IL-1β. This study describes a potentially important inflammatory mechanism of silicosis that may bring about novel therapies for this inflammatory and fibrotic disease.