Abstract 392: TAT-PHLPP9c and TAT-PIF Administration During CPR Synergistically Improves Cardiac Arrest Survival

Introduction: We have demonstrated that a novel fast-acting peptide TAT-PHLPP9c improves survival in both mouse and swine models of cardiac arrest. The protective effect is mediately by activation of Akt via inhibiting phosphatase PHLPP. We have designed another peptide TAT-PIF to activate Akt by promoting the active conformation of PDK1 via binding to PDK1 Interacting Fragment (PIF).

Hypothesis: We hypothesize that TAT-PHLPP9c and TAT-PIF synergistically enhance Akt activation and improve cardiac arrest survival when administered intravenously during CPR.

Methods: Cardiomyocytes were treated with TAT-PHLPP9c (10uM), or TAT-PIF (10uM) or in combination. Akt phosphorylation (p-Akt) at both Thr308 and Ser473 sites were assessed by Western blot. In C57BL/6 retired female mice (n=24), a 12-min asystolic cardiac arrest was induced with KCl followed by CPR and blinded randomized administration of the peptides or saline control. Four experimental groups were included: 1) saline, 2) TAT-PHLPP9c (7.5 mg/kg), 3) TAT-PIF (7.5 mg/kg), 4) TAT-PHLPP9c and TAT-PIF. Survival was evaluated at 4 hour post-ROSC.

Results: In cardiomyocytes, compared to saline, both TAT-PHLPP9c and TAT-PIF independently increased AktSer473 phosphorylation, and the combined treatment of both peptides synergistically enhanced p-AktSer473. For AktThr308 site, TAT-PIF increased its phosphorylation while TAT-PHLPP9c induced a slight increase of its phosphorylation. Enhanced phosphorylation was also seen with the combined treatment. In mice, compared to saline control, both peptides improved 4-h survival when given alone, but the combined treatment improved 4-h survival synergistically over 30%.

Conclusions: The cocktail of TAT-PHLPP9c and TAT-PIF may be a novel treatment regimen for improving outcome following cardiac arrest.