Atelectrauma disrupts pulmonary epithelial barrier integrity and alters the distribution of tight junction proteins ZO-1 and claudin 4

Jacob AM, Gaver DP III. Atelectrauma disrupts pulmonary epithelial barrier integrity and alters the distribution of tight junction proteins ZO-1 and claudin 4. J Appl Physiol 113: 1377-1387, 2012. First published August 16, 2012; doi:10.1152/japplphysiol.01432.2011.-Mechanical ventilation inevitably exposes the delicate tissues of the airways and alveoli to abnormal mechanical stresses that can induce pulmonary edema and exacerbate conditions such as acute respiratory distress syndrome. The goal of our research is to characterize the cellular trauma caused by the transient abnormal fluid mechanical stresses that arise when air is forced into a liquid-occluded airway (i.e., atelectrauma). Using a fluid-filled, parallel-plate flow chamber to model the "airway reopening" process, our in vitro study examined consequent increases in pulmonary epithelial plasma membrane rupture, paracellular permeability, and disruption of the tight junction (TJ) proteins zonula occludens-1 and claudin-4. Computational analysis predicts the normal and tangential surface stresses that develop between the basolateral epithelial membrane and underlying substrate due to the interfacial stresses acting on the apical cell membrane. These simulations demonstrate that decreasing the velocity of reopening causes a significant increase in basolateral surface stresses, particularly in the region between neighboring cells where TJs concentrate. Likewise, pulmonary epithelial wounding, paracellular permeability, and TJ protein disruption were significantly greater following slower reopening. This study thus demonstrates that maintaining a higher velocity of reopening, which reduces the damaging fluid stresses acting on the airway wall, decreases the mechanical stresses on the basolateral cell surface while protecting cells from plasma membrane rupture and promoting barrier integrity.