[Mechanisms of pulmonary fibrosis]

Lung fibrosis is characterized by the accumulation of extracellular matrix and mesenchymal cells leading a progressive loss of respiratory functional units. The accumulation of mesenchymal cells results from their migration and local replication. These cellular events are dependent upon the local presence of cytokines with chemotactic and/or mitogenic activity. The sequence of events leading the lung fibrosis is thought to result from a stereotyped response: after an initial injury, an inflammatory reaction develops and controls tissue repair through local production of cytokines. The permanency of these processes results in the development of fibrosis.