Immunology of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is an immunomediated disorder characterized by a chronic inflammation of the lower respiratory tract, type I epithelial cell damage, accumulation of connective tissue components, fibroblast proliferation, and deposition of matrix proteins. The past few years have seen remarkable advances in the understanding of the immunopathogenesis of IPF. It is becoming clear that, although normal inflammatory reaction in the lung generally resolves, the rapidity and efficiency with which inflammatory constituents are removed from alveolar airspaces is altered in patients with IPF. The loss of the balance between events that mediate resolution or perpetuation of inflammatory responses sets the stage for severe lung injury, tissue remodelling, and the irreversible development of pulmonary fibrosis. This review outlines the complexity of cellular signalling processes taking place in fibrotic lung, providing a bridge between basic research and clinical relevance in the treatment of these patients.