Clara Cell Protein CC16: A New Lung Epithelial Biomarker for Acute Lung Injury

摘要

There has been considerable interest in the contribution of lung epithelial injury to the pathogenesis of acute lung injury (ALI). Injury to the alveolar epithelium leads to alveolar edema, a decrease in surfactant activity, a reduction in alveolar fluid clearance, and more procoagulant and antifibrinolytic activity in the distal airspaces of the lung.1–3 One approach to estimating the degree of lung epithelial injury has been to measure plasma and airspace biomarkers of alveolar epithelial injury in patients with ALI. In addition to providing more insight into pathogenesis, biomarkers of lung epithelial injury may also have diagnostic value for differentiating cardiogenic edema from primary lung injury edema, particularly since the diagnostic criteria for ALI,4 bilateral chest radiographic infiltrates with arterial hypoxemia (PaO2/FiO2 ratio, < 300), are often present in patients with acute respiratory failure from cardiogenic edema as well as in patients with ALI.5 Also, elevated lung microvascular pressure often coexists in patients with ALI, as has been reported in the ARDS Network Fluid and Catheter Treatment Trial,6 in which 29% of patients in whom ALI had been diagnosed had a pulmonary artery wedge pressure of > 18 mm Hg. Thus, a biomarker that helps to make the diagnosis of ALI would be valuable to both guide clinical management as well as to define a more homogenous patient cohort for clinical trials of ALI.