Caveolin-1 siRNA increases the pulmonary microvascular and alveolar epithelial permeability in rats.
BACKGROUND
Increased pulmonary microvascular and epithelial permeability are important contributors to pulmonary edema in acute lung injury. In this study, we used small interfering RNA (siRNA) to knock down caveolin-1 expression in rat lungs and to confirm the important role of caveolin-1 in regulating pulmonary edema.


METHODS
After pulmonary injection of siRNA against caveolin-1 messenger RNA incorporated in liposomes with three concentrations of 0.4, 0.8, and 1.2 mg/kg, the gene silencing rate and the effects of caveolin-1 siRNA on aquaporin (AQP)-1, AQP-5, and epithelial sodium channel (ENaC) were detected. For pulmonary permeability analysis, Evans blue fluorimetry, ratios of albumin concentrations between blood and bronchoalveolar lavage, and wet/dry weight ratios were measured. The impacts of caveolin-1 suppression on interendothelial junctions were evaluated by the performance of electron microscopy and the analysis of vascular endothelial (VE)-cadherin Western blot. Alveolar wall thickness analysis and chest fluoroscopy were performed to determine the pulmonary edema degree.


RESULTS
After 72 hours of injection, the gene silencing rate of caveolin-1 siRNA is about 87%. AQP-1, AQP-5, ENaC-α, ENaC-β, ENaC-γ, and VE-cadherin protein levels were decreased by 63%, 66%, 80%, 90%, 89%, and 50%, respectively. Caveolin-1 siRNA also resulted in increasing microvascular and epithelial permeability and pulmonary edema.


CONCLUSIONS
These data suggest that caveolin-1 plays an important part in regulating the pulmonary permeability by modifying AQP-1, AQP-5, ENaC, and VE-cadherin.
Gao
Chengjin
C
Department of Burn and Plastic Surgery, Rui Jin Hospital, Shanghai Jiao Tong University, School of Medicine, Shanghai, China.
Li
Rongrong
R
Huan
Jingning
J
Li
Wei
W
D000818:Animals; D051398:Aquaporin 1 / Q000096:biosynthesis; D051402:Aquaporin 5 / Q000096:biosynthesis; D015153:Blotting, Western; D002199:Capillary Permeability / Q000502:physiology*; D051242:Caveolin 1 / Q000235:genetics* / Q000502:physiology; D053503:Epithelial Sodium Channels / Q000096:biosynthesis; D005070:Evans Blue; D005470:Fluorometry; D020868:Gene Silencing / Q000502:physiology; D008297:Male; D055806:Microvessels / Q000502:physiology* / Q000648:ultrastructure; D011650:Pulmonary Alveoli / Q000098:blood supply* / Q000502:physiology / Q000648:ultrastructure; D034741:RNA, Small Interfering / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020545:Respiratory Mucosa / Q000098:blood supply / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction
C496040:Aqp5 protein, rat; D051402:Aquaporin 5; D051242:Caveolin 1; D053503:Epithelial Sodium Channels; D034741:RNA, Small Interfering; D051398:Aquaporin 1; D005070:Evans Blue