Biochemical and anatomical study of collagen and associated macromolecules in pulmonary panacinar emphysema and spontaneous pneumothorax.

In collagen content of four emphysematous lungs as defined by radiological, physiological and anatomical tests were studied. They were compared to three control lungs and five lungs removed from patients with relapsing pneumothorax (PNO). Morphologically, emphysematous lungs were characterized by patchy disorganization of collagen fibers, involving microfibrillar areas or elastoid laminae. Elastic fibers were at times found in plugs. Such abnormalities were also present, but less frequently in the PNO group. Biochemically, emphysematous lungs showed an increase of soluble proteins removed by CaCl2 extraction, which were associated with a decrease in insoluble proteins in extracted by TCA. Total hydroxyproline, expressed as a fraction of deoxyribonucleic acid (DNA) content, was not modified, but an increase of dialyzable and undialyzable fraction was observed in MEM medium. The PNO group showed the same modifications in terms of mean values, but individual results were more scattered. Results of in vitro 14C-proline incorporation did not show any modification of collagen biosynthesis, except in 2 emphysematous lungs. The results indicate that the PNO group is nearer to the emphysematous group than the controls. This suggests that patients with relapsing PNO may develop emphysema but it has to be further substantiated. The results here presented indicate that soluble hydroxyproline is an index either of abnormal synthesis or of excessive collagenolysis.