[Pulmonary fibrous ground substance. Macromolecules of the intercellular matrix]

Four families of macromolecules make up the pulmonary fibrous connective tissue which one finds in all connective tissue: collagen elastin, the proteoglycans and the structural glycoproteins. The regulation of the synthesis of these macromolecules and their arrangement and interaction within the intracellular space are conditions necessary for the development and maintenance of a normal pulmonary fibrous connective tissue. The quantitative relationship of these macromolecules changes with age; it is also profoundly modified in chronic obstructive lung disease. An understanding of the pathogenesis of the modifications, requires the study of the regulatory mechanisms involved in the synthesis and degradation of the macromolecules of the pulmonary connective tissue. In recent years we have made some progress in the domain of the regulation of the synthesis and degradation of collagen, but we still know very little about elastin. Over the past few years our laboratory has isolated several cellular elastases which probably intervene in these processes. Elastoplastic proteases have been isolated from platelets, leucocytes, macrophages, fibroblasts and smooth muscle cells. Human serum and purified lipoproteins also possess an elastolytic activity which is easily measured in clinic. Which of these enzymes is responsible for the lysis of the elastic laminae seen in emphysema has not yet been established. It seems possible that one important factors in certain pathological states is the faulty protection given by modified serum inhibitors. Our recent studies with Mrs Ch. LAMFUMA and Mrs MOCZAR suggest an important role for the structural glycoproteins in the pulmonary connective tissue. It is possible that qualitative an or quantitative modifications in these glycoproteins could also play an important role in pathology.