Is Immune Response Relevant in Interstitial Lung Disease?

Interstitial lung disease, a term for a group of disorders, causes lung fibrosis, is mostly refractory to treatments and has a high death rate. After diagnosis the survival is up to 3 years but in some cases the patients live much longer. It involves a heterogenous group of lung diseases that exhibit progressive and irreversible destruction of the lung due to the formation of scars. This results in lung malfunction, disruption of gas exchange, and eventual death because of respiratory failure. The etiology of lung fibrosis is mostly unknown with a few exceptions. The major characteristics of the disease are comprised of injury of epithelial type II cells, increased apoptosis, chronic inflammation, monocytic and lymphocytic infiltration, accumulation of myofibroblasts, and inability to repair damaged tissue properly. These events result in abnormal collagen deposition and scarring. The inflammation process is mild, and the disease is primarily fibrotic driven. Immunosuppressants do not treat the disease but the evidence is evolving that both innate and acquired immune responses a well as the cytokines contribute to at least early progression of the disease. Furthermore, mediators of inflammation including cytokines are involved throughout the process of lung fibrosis. The diverse clinical outcome of the disease is due to different pattern of inflammatory markers. Nonetheless, the development of novel therapeutic strategies requires better understanding of the role of the immune response. This review highlights the role of the immune response in interstitial lung disease and considers the therapeutic strategies based on these observations. For this review several literature data sources were used to assess the role of the immune response in interstitial lung disease and to evaluate the possible therapeutic strategies for the disease.