[Pathophysiology of acute lung injury]

Almost all respiratory diseases except benign lung tumors and lung dysplasia entail acute lung injury. The many clinical conditions associated with acute lung injury include aspiration pneumonia, bacterial pneumonia, and sepsis. The fundamental cause of acute lung injury is pulmonary vascular hyperpermeability. Pulmonary vascular hyperpermeability can be attenuated by nitric oxide and cyclic GMP, and potentiated by oxygen radicals and elastase released from neutrophils. Adhesion molecule inhibition could become an effective therapy against acute lung injury, because the adhesion molecules are very important in the pathogenesis of this condition. Adhesion molecules could also be useful markers of disease activity in various lung diseases. Neutrophil elastase inhibitors may become important as therapeutic agents against acute exacerbations of idiopathic interstitial pneumonia, because this pathological condition is a type of acute lung injury. Similarly, N-acetyl cysteine could also become a useful therapeutic agent against idiopathic interstitial pneumonia, because it is a precursor of glutathione, which is the major antioxidant in the fluid lining of the bronchial epithelium.