Proteinase imbalance versus biomechanical stress in pulmonary emphysema.

Emphysema is a slowly progressive degenerative lung disease involving fragmentation and depletion of elastic fibers, loss of lung elastance, and architectural destruction with ectasia, tortuosity, and loss of bronchioles irrespective of localization or morphological type. Occurring under physiological conditions, predominantly in geriatrics, matrix laxity and destructive parenchymal lesions are indicative of a pathological loss of tissue tensile strength attributable to bioengineering or structural fatigue in repetitively stressed tissues. The occurrence of severe premature emphysema in inherited connective tissue diseases and under some experimental and iatrogenic conditions is supportive evidence. Experiments advocating unrestrained proteolysis as a cause or pathogenic factor are invalid, being based on a false premise and assumed causality.