Interstitial lung disease in connective tissue disease--mechanisms and management.

Pulmonary complications are an important extra-articular feature of autoimmune rheumatic diseases and a major cause of mortality. The underlying pathogenesis probably involves multiple cellular compartments, including the epithelium, lung fibroblasts, and the innate and adaptive immune system. Heterogeneity in the extent and progression of lung fibrosis probably reflects differences in underlying pathogenic mechanisms. Growing understanding of the key pathogenic drivers of lung fibrosis might lead to the development of more effective targeted therapies to replicate the treatment advances in other aspects of these diseases. Interstitial lung disease (ILD) in connective tissue disease (CTD) is characterized using the classification of the idiopathic interstitial pneumonias. Systemic sclerosis is most frequently associated with ILD and, in most of these patients, ILD manifests as a histological pattern of nonspecific interstitial pneumonia. Conversely, in rheumatoid arthritis, the pattern of ILD is most often usual interstitial pneumonia. The key goals of clinical assessment of patients with both ILD and CTD are the detection of ILD and prognostic evaluation to determine which patients should be treated. Data from treatment trials in systemic sclerosis support the use of immunosuppressive therapy, with the treatment benefit largely relating to the prevention of progression of lung disease.