O101 Mitochondrial P53 inhibition ameliorates acute pancreatitis through reduction of mitochondrial injury and cell necrosis

Abstract

Abstract Introduction Persistent opening of the mitochondrial permeability transition pore (MPTP) is central to acute pancreatitis (AP). Mitochondrial translocation of P53 promotes MPTP opening, which induces necrotic cell death. We sought to determine whether and how mitochondrial P53 inhibition is protective in experimental AP. Methods Mitochondrial translocation of P53 was inhibited by pifithrin-mu (PFT-µ, mitochondrial specific P53 inhibitor) or by Trp53 KO. Mitochondrial membrane potential (ΔΨm) and necrosis of murine pancreatic acinar cells (PACs) were evaluated by confocal microscopy with TMRM and propidium iodide, respectively, in the presence of TLCS. Fluo4 was used for calcium imaging. Caerulein AP (Cer-AP) was induced in male (WT, P53−/+, P53−/−; 10-12 week old) mice by 7 hourly i.p. injections of 50 μg/kg caerulein. PFT-µ (5 mg/kg) was injected after the third injection of caerulein; sacrifice was made 12h after the first injection of caerulein. AP was assessed by standard biomarkers and blinded histopathology. Results TLCS-induced collapse of ΔΨm and cell necrosis of wild type PACs were significantly reduced in the presence of PFTµ or in PACs isolated from Trp53 KO mice; calcium overload was also reduced, indicative of improved calcium clearance, and ATP was maintained. Pharmacological or genetic P53 inhibition resulted in significant reductions of biochemical, immunological, and histopathological indices of severity in the Cer-AP model. Conclusion Inhibition of P53 maintained mitochondrial integrity, reduced PACs necrosis, and ameliorated the severity of Cer-AP. These data suggest that inhibition of mitochondrial translocation of P53 could be an effective strategy for the treatment of AP.