Cyclosporine A--protection against microvascular hyperpermeability is calcineurin independent.
BACKGROUND
Mitochondria-mediated apoptotic signaling contributes to microvascular hyperpermeability. We hypothesized that cyclosporine A (CsA), which protects mitochondrial transition pores, would attenuate hyperpermeability independent of its calcineurin inhibitory property.


METHODS
Hyperpermeability was induced in microvascular endothelial cell monolayers using proapoptotic BAK or active caspase-3 after CsA or a specific calcineurin inhibitor, calcineurin autoinhibitory peptide (CIP), treatment. Permeability was measured based on fluorescein isothiocyanate-albumin flux across the monolayers. Mitochondrial transmembrane potential (MTP) was determined using 5,5',6,6'-tetrachoro-1,1',3,3'-tetraethylbenzimidazolyl carbocyanine iodide. Mitochondrial release of cytochrome c was measured using an enzyme-linked immunosorbent assay and caspase-3 activity fluorometrically.


RESULTS
CsA-attenuated (10 nmol/L) but not CIP-attenuated (100 mumol/L) BAK induced hyperpermeability (P < .05), CsA- but not CIP-attenuated BAK induced a decrease in MTP and an increase in cytochrome c levels and caspase-3 activity (P < .05). CsA and CIP were ineffective against caspase-3-induced hyperpermeability.


CONCLUSIONS
CsA attenuated hyperpermeability by protecting MTP, thus preventing mitochondria-mediated apoptotic signaling. The protective effect of CsA is independent of calcineurin inhibition.
Childs
Ed W
EW
Department of Surgery, Texas A&M Health Science Center College of Medicine and Scott & White Memorial Hospital, 2401 South 31st St., Temple, TX 76508, USA. echilds@swmail.sw.org
Tharakan
Binu
B
Nurudeen
Suliat
S
Delmas
Thomas L
TL
Hellman
Joseph
J
Christie
Tasheika
T
Hunter
Felicia A
FA
Smythe
W Roy
WR
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins; D019703:Calcineurin / Q000378:metabolism*; D002199:Capillary Permeability / Q000187:drug effects*; D002352:Carrier Proteins / Q000378:metabolism*; D061945:Caspase Inhibitors; D016572:Cyclosporine / Q000494:pharmacology*; D045304:Cytochromes c / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects*; D008168:Lung / Q000098:blood supply*; D008833:Microcirculation; D008928:Mitochondria / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects
D051017:Apoptosis Regulatory Proteins; C113573:Cabin1 protein, rat; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D016572:Cyclosporine; D045304:Cytochromes c; D019703:Calcineurin