Differential regulation of pulmonary endothelial monolayer integrity by varying degrees of cyclic stretch.
Ventilator-induced lung injury is a life-threatening complication of mechanical ventilation at high-tidal volumes. Besides activation of proinflammatory cytokine production, excessive lung distension directly affects blood-gas barrier and lung vascular permeability. To investigate whether restoration of pulmonary endothelial cell (EC) monolayer integrity after agonist challenge is dependent on the magnitude of applied cyclic stretch (CS) and how these effects are linked to differential activation of small GTPases Rac and Rho, pulmonary ECs were subjected to physiologically (5% elongation) or pathologically (18% elongation) relevant levels of CS. Pathological CS enhanced thrombin-induced gap formation and delayed monolayer recovery, whereas physiological CS induced nearly complete EC recovery accompanied by peripheral redistribution of focal adhesions and cortactin after 50 minutes of thrombin. Consistent with differential effects on monolayer integrity, 18% CS enhanced thrombin-induced Rho activation, whereas 5% CS promoted Rac activation during the EC recovery phase. Rac inhibition dramatically attenuated restoration of monolayer integrity after thrombin challenge. Physiological CS preconditioning (5% CS, 24 hours) enhanced EC paracellular gap resolution after step-wise increase to 18% CS (30 minutes) and thrombin challenge. These results suggest a critical role for the CS amplitude and the balance between Rac and Rho in mechanochemical regulation of lung EC barrier.
Birukova
Anna A
AA
Department of Medicine, Section of Pulmonary and Critical Care Medicine, University of Chicago, Chicago, Illinois 60637, USA.
Chatchavalvanich
Santipongse
S
Rios
Alexander
A
Kawkitinarong
Kamon
K
Garcia
Joe G N
JG
Birukov
Konstantin G
KG
D018929:Cell Culture Techniques; D015536:Down-Regulation; D042783:Endothelial Cells / Q000502:physiology*; D004789:Enzyme Activation; D022001:Focal Adhesions / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008168:Lung / Q000502:physiology*; D008387:Marine Toxins / Q000235:genetics; D008954:Models, Biological; D013314:Stress, Mechanical; D013917:Thrombin / Q000494:pharmacology; D014178:Translocation, Genetic; D020744:rac GTP-Binding Proteins / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
D008387:Marine Toxins; C066979:contractin A; D013917:Thrombin; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins