Vitronectin and its relationship to other extracellular matrix components in bronchoalveolar lavage fluid in sarcoidosis.

There is a need to find markers that can be used as indicators of early fibrotic changes in the lung in patients with sarcoidosis. The fibrotic reaction is accompanied by an increase in the connective tissue components, and the extracellular matrix molecules are characterized by an ability to interact with each other. We found increased concentrations of three components of the extracellular matrix, vitronectin (VN), fibronectin (FN), and hyaluronan (HA), in bronchoalveolar lavage (BAL) fluid from 56 patients with sarcoidosis compared with 38 healthy control subjects (p less than 0.001 for all). Using an enzyme-linked immunosorbent assay, the median value for VN in BAL fluid from sarcoid patients was 74 micrograms/L (interquartile range, 47 to 138) compared with 38 micrograms/L (IQR, 22 to 55) in control subjects. The median VN concentration in serum was 0.25 g/L in both groups. VN consists of various functional domains, and it may, together with FN and HA, contribute to repair or exaggeration of the interstitial changes that occur when sarcoidosis affects the lungs. VN correlated to the concentration of albumin in the BAL fluid (p less than 0.01) but even closer to the concentrations of FN and HA (p less than 0.001 for both). The extracellular matrix components did not show any correlation to the disease activity, roentgenographic stage, or functional signs of developed fibrosis. In conclusion, the increased concentrations of VN, FN, and HA may predict only an ongoing inflammation and not necessarily a fibrotic process.