Genotype-dependent values of serum biomarkers in interstitial lung diseases

Interstitial lung diseases (ILDs) are a group of more than hundred heterogeneous disease entities sharing the pulmonary interstitium as primary focus of origin or manifestation of pathogenesis. Sarcoidosis (M. Besnier-Boeck), the most common ILD, is stereotyped for the presence of lung-localized, noncaseating granulomas of unknown origin (1). Stereotyped indeed, since sarcoidosis as a disease displays such a clear heterogeneity in partly overlapping characteristics or phenotypes that 'sarcoidoses' is a factually better description than sarcoidosis. For instance, Löfgren's syndrome, a spontaneously-resolving disease within a few months to two years and leaving no physical limitations has a clearly distinct disease course than chronic sarcoidosis leading to fibrosis of the lung and finally to the necessity of a lung transplantation. In the 'sarcoidoses', granulomas are also localized extrapulmonary making disease management even more challenging. Triggered by the clearly recognizable granuloma, consisting of a gathering of macrophages and T-cells, numerous speculations about the trigger or triggers causing sarcoidoses could not be substantiated. An environmental e.g. extracorporal trigger, obviously a chemical substance being most probably part of a micro-organism, in combination with the personal genetic layout and immune status, results in a patient's unique course of sarcoidosis (2). In many cases ILDs exhibit a unique disease course through the unique composition of an individual's genome and the involvement of not only the innate immune system, but also the dynamic processes of fibrogenesis and tissue remodelling in not only the environmentally exposed lungs but also in other organs. Idiopathic pulmonary fibrosis (IPF), a devastating disease in the group of ILDs, is characterized by an unknown cause of onset of pulmonary fibrosis progressing towards inevitable lung transplantation. The severe manifestations of sarcoidoses and IPF, which are overlapping with both familial pulmonary fibrosis and sarcoidoses, require improvement of treatment possibilities (3, 4).