Preconditioning effects of physiological cyclic stretch on pathologically mechanical stretch-induced alveolar epithelial cell apoptosis and barrier dysfunction.
BACKGROUND
We aim to investigate the effects of preconditioning of physiological cyclic stretch on the alveolar epithelial cell apoptosis induced by pathologically mechanical stretch and barrier dysfunction and how these effects are linked to differential expression of small GTPases Rac and Rho mRNA.


METHODS
Pulmonary alveolar epithelial cells were subjected to different treatments of cyclic stretch (CS) at 5% and 20% elongation, respectively. Cells maintained in normal cell culture were used as negative control. On the other hand, cell apoptosis and Rac/Rho activities in cells with or without preconditioning of physiologically relevant magnitudes of CS (5% CS) with different durations (0, 15, 30, 60 and 120 min) in prior to 6-h treatment with pathological CS stimulation (20% CS) were compared and measured.


RESULTS
Pathological CS could cause a significant increase in apoptosis rate, which is considered to be associated with the repression of Rac mRNA and activation of Rho mRNA. In contrast, physiological 5%-CS preconditioning suppressed cell apoptosis and induced nearly complete monolayer recovery with fewer actin stress fibers and paracellular gap formation. Consistent with differential effects on cell apoptosis and epithelial cell integrity, physiological CS preconditioning enhanced expression of Rac mRNA but inhibited Rho activation.


CONCLUSIONS
Physiological CS preconditioning has an inhibitory effect on cell apoptosis while exerts a stimulatory impact on epithelial cell recovery via regulation of Rac and Rho activities.
Department of Anesthesiology, Subei People's Hospital of Jiangsu Province, Clinical Medical School of Yangzhou University, China.
Ju
J
Gao
Department of Anesthesiology, Subei People's Hospital of Jiangsu Province, Clinical Medical School of Yangzhou University, China.
Tao
T
Huang
Department of Scientific Research, Subei People's Hospital of Jiangsu Province, China. Electronic address: 930769429@qq.com.
Luo-Jing
LJ
Zhou
Department of Anesthesiology, Subei People's Hospital of Jiangsu Province, Clinical Medical School of Yangzhou University, China.
Ya-Li
YL
Ge
Department of Anesthesiology, Subei People's Hospital of Jiangsu Province, Clinical Medical School of Yangzhou University, China.
Shun-Yan
SY
Lin
Department of Scientific Research, Subei People's Hospital of Jiangsu Province, China.
Yan
Y
Dai
D000199:Actins / Q000378:metabolism; D056809:Alveolar Epithelial Cells / Q000473:pathology* / Q000502:physiology*; D017209:Apoptosis; D002460:Cell Line; D015870:Gene Expression; D006801:Humans; D055370:Lung Injury / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012121:Respiration, Artificial / Q000009:adverse effects; D013314:Stress, Mechanical; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
D000199:Actins; C107953:RAC1 protein, human; D012333:RNA, Messenger; C066737:RHOA protein, human; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein
Actin; Cytoskeleton; Lung injury; Mechanical ventilation; Rac GTPase; RhoA GTPase