title: RECOMBINANT BCL-XL ATTENUATES VASCULAR HYPERPERMEABILITY IN A RAT MODEL OF HEMORRHAGIC SHOCK.
abstract: Following hemorrhagic shock (HS), vascular hyperpermeabilityi.e. the leakage of fluid, nutrients and proteins into the extravascular space occurs primarily due to the disruption of the endothelial cell-cell adherens junctional complex. Studies from our laboratory demonstrate that activation of the mitochondria mediated 'intrinsic' apoptotic signaling cascade has a significant role in modulating HS-induced hyperpermeability. Here we report the novel use of recombinant Bcl-xL, an anti-apoptotic protein, to control HS-induced vascular hyperpermeability. Our results corroborate involvement of vascular hyperpermeability and apoptotic signaling. Hemorrhagic shock (HS) (mean arterial pressure [MAP] was reduced to 40 mmHg for 60 minutes followed by resuscitation to 90 mmHg for 60 minutes) in rats resulted in vascular hyperpermeability as determined by intra-vital microscopy. Treatment of Bcl-xL (2.5ug/ml of rat blood in non-lipid cationic polymer, i.v.) before, during and even after HS attenuated or reversed HS-induced vascular hyperpermeability significantly (p<0.05). Conversely, treatment using Bcl-xL inhibitors, 2-methoxy antimycin (2-MeOAA) and ABT 737, significantly increased vascular hyperpermeability compared to sham (p<0.05). Bcl-xL treatment also decreased the amount of fluid volume required to maintain a MAP of 90 mmHg during resuscitation (p<0.05). HS resulted in increased mitochondrial ROS formation, reduction of ΔΨm, mitochondrial release of cytochrome c and significant activation of caspase-3 (p<0.05). All of these effects were significantly inhibited by Bcl-xL pre-treatment (p<0.05). Our results show that recombinant Bcl-xL is effective against HS-induced vascular hyperpermeability that appears to be mediated through preservation of ΔΨm and subsequent prevention of caspase-3 activation.
authors.affiliation: Department of Surgery, Texas A&M University Health Science Center College of Medicine and Baylor Scott & White Healthcare, Temple, TX. USA.
authors.forename: Binu
authors.initials: B
authors.lastname: Tharakan
authors.affiliation: Department of Surgery, Morehouse School of Medicine, Atlanta, GA. USA.
authors.forename: Sam I
authors.initials: SI
authors.lastname: McNeal
authors.affiliation: Department of Surgery, Morehouse School of Medicine, Atlanta, GA. USA.
authors.forename: Felicia A
authors.initials: FA
authors.lastname: Hunter
authors.affiliation: School of Anatomical Science, Alderson Broaddus University, Philippi, WV. USA.
authors.forename: Devendra A
authors.initials: DA
authors.lastname: Sawant
authors.affiliation: AVIA Health Innovation, Chicago, IL. USA.
authors.forename: W Roy
authors.initials: WR
authors.lastname: Smythe
authors.affiliation: Department of Surgery, Morehouse School of Medicine, Atlanta, GA. USA.
authors.forename: Ed W
authors.initials: EW
authors.lastname: Childs
keywords: ABT 737; Apoptosis; Bcl-xL; Endothelial Cells; Hemorrhagic Shock