Abstract 16947: Mitochondrial Calcium Uniporter Channel Blockade Ameliorates Sepsis Induced Cardiomyopathy

Abstract

Introduction: Mitochondria serve as critical Ca 2+ sinks, regulating the duration and magnitude of c Ca2+ transients and c Ca2+ entry into the mitochondrion. Mitochondrial calcium uniporter (MCU) channel is activated in conditions of inflammation and oxidative stress.MCU and its activity are potential therapeutic targets for cardiac hypertrophy and heart failure. Hypothesis: Blunting of mCa2+ uptake can contribute to increased cCa2+ transients associated with excitation-contraction coupling and offer cardio protection following sepsis induced stress. Methods: MCU C96A KI generated using CRISPR-Cas9 d10 nickase mRNA co-injected with gRNA into wild-type(C57BL6) zygotes and then implanted into pseudo-pregnant female mice.To elucidate mechanistic role of mCa2+ in modulating cardiac contractility and myocardial bioenergetics, adult cardiomyocytes were isolated from mouse model and subjected to hypoxia/re-oxygenation injury.Polymicrobial Sepsis in 6-week-old C57BL/6J mice were created using Cecal ligation and puncture (CLP) and MCU oxidation at 1, 6, 12 and 24 hours post injury was compared with Sham and control mice (n=15). MCU protein quantification was done with western blot, functional assessment of Reactive oxygen species (ROS) by confocal laser microscopy, echocardiography with Vevo2100 imaging system. Mice were pretreated with MCU blocking agent Ru360 1 hr prior to CLP and compared with the control group at 6 hours. Results: Cardiomyocytes exposed to hypoxia/re-oxygenation(h/R ) stress exhibited increased MitoSOX red fluorescence.MCU oxidation was ubiquitously induced in all tissues post CLP surgery and was most significant at 6 hrs (Fig 1a). Oxidation of MCU was marked by increase in ROS in tissue sections of small Intestine of CLP versus the Sham group(p<0.001). (Fig 1 b &c). Pretreatment with Ru360 ameliorated MCU oxidation at 6 hours post CLP injury. MCUC96AKI had significantly decreased ejection fraction and fractional shortening compared to the wild type mice. Further the survival in MCU C96A KI was significantly better than the WT or MCU KO mice ( p<0.05). Conclusions: Inhibition of mitochondrial calcium uniporter is a potential therapeutic target and protects from sepsis induced cardiomyopathy by mitigating mitophagy.