Autoimmunity and interstitial lung disease

The pathogenesis of idiopathic pulmonary fibrosis as well as that of several other interstitial lung diseases is poorly understood. The role of autoimmunity in interstitial lung diseases associated with connective tissue disorders such as systemic sclerosis, systemic lupus erythematosus, and rheumatoid arthritis as well as the vasculitides is well established. There is at least some evidence in the literature that supports the role of autoimmunity as one of the mechanisms of alveolar injury responsible for idiopathic pulmonary fibrosis. This review is an attempt to summarize the studies on this subject.

Repeated extraneous insults and exposures are considered to be responsible for recurrent alveolar injury, inflammation, dysregulated tissue repair, and fibroproliferation resulting in pulmonary fibrosis. The presence of autoantibodies in the sera of patients with idiopathic pulmonary fibrosis has been demonstrated in a few studies. Several autoantibodies, including anti-Sm antibodies, antibodies to U1 ribonucleoproteins, and antibodies to U3 ribonucleoproteins, have been demonstrated in connective tissue disorders, many of which are associated with interstitial lung involvement. Autoimmunity has been also suggested as a possible mechanism of rejection caused by bronchiolitis obliterans after lung transplantation.

It might seem that the role of autoimmunity in interstitial lung disease has been underestimated or even underinvestigated. The subject requires further investigation, especially with regard to the problems of lung allograft rejection due to bronchiolitis obliterans of nonalloimmunity origin and the failure of patients with idiopathic pulmonary fibrosis to respond to most forms of currently available therapy.