EXPRESSION OF LUMICAN IN HUMAN LUNGS

The collagen-elastin-proteoglycan (PG) matrix is the key constituent o f lung parenchyma and plays a major role in the mechanical behavior of lung tissues. However, the exact composition of the PG matrix in lung s has not yet been fully determined. In the present study we report th e expression of leucine-rich repeat PGs in adult human lungs. PG extra ction was performed on peripheral lung tissue from patients undergoing therapeutic lung resections. The samples were analyzed by sodium dode cyl sulfate-polyacrylamide gel electrophoresis and immunoblotting usin g antipeptide antisera specific to human lumican, decorin, biglycan, a nd fibromodulin. Control experiments to verify antiserum reactivity we re performed with an extract of adult human articular cartilage, which is known to contain all four PGs. In all lung extracts analyzed, a si ngle component of molecular weight 65 to 90 kD was detected for lumica n. Decorin, biglycan, and fibromodulin were either not detected or wer e barely detectable in the lung extracts, but were readily visualized in the cartilage samples. Immunohistochemistry showed that lumican was diffusely present in peripheral lung tissue, mainly in vessel walls. These results suggest that lumican is a major component of the PG matr ix in adult human lungs.