Sepsis is the leading cause of death in the critically ill patient, and mortality is directly associated to organ dysfunction. Acute kidney injury (AKI) occurs in 40-50% of septic patients, and increases mortality 5-6 fold. The mechanisms by which sepsis produces organ dysfunction are unknown. Previous data have shown that in hemorrhage, stimulation of autophagy by activation of AMP-activated protein kinase (AMPK) protects against hepatocyte death. The objective of this study was to assess the role of activation/inhibition of AMPK in the development of organ injury in the setting of sepsis.
We hypothesize that in sepsis, stimulation of AMPK will protect against organ injury.
Thirty C57BL/6 male mice, 6-8 weeks of age, and weighting 20+/-5 g were anesthetized with intraperitoneal pentobarbital injection at 70 mg/kg, and divided into six groups: A. Cecal Ligation and Puncture (CLP); B. CLP+AICAR (AMPK stimulant); C. CLP+Compound C (CoC;AMPK inhibitor); D. Sham; E. Sham+AICAR; F. Sham+Compound C. Shams underwent laparotomy alone. AICAR and CoC were given 24 hours prior to CLP at 100 mg/kg and 30 mg/kg, respectively. Animals were resuscitated with 1ml of normal saline and no antibiotics. Tissue and blood were collected at 8 hours post-CLP. Renal and hepatic function was measured with Cystatin C (ng/mL) and AST/ALT (IU/L). Data is presented as mean+/-SD. Statistical significance is defined as p value <0.05.
Cystatin C levels were elevated in CLP and CLP+CoC groups, as compared to sham (3175+/-1296 and 3133+/-1843 vs. 733+/-82, respectively), but not in CLP+AICAR (1401+/-741) showing statistical significance. A similar pattern was seen in liver function tests, with elevation in ALT/AST in the CLP and CLP+CoC groups (156+/-76/459+/-206 and 176+/-52/449+/-192), but not in CLP+AICAR (98+/-13/288+/-42) as compared to Sham (79+/-55/298+/-91). These values did reach not statistical significance.
In this model of severe sepsis and organ injury, activation of AMPK reduced renal injury as measured by Cystatin C, and inhibition exacerbated it. These data suggests that energy regulatory pathways such as AMPK modulation, and potentially autophagy may be fundamental in the development of organ injury.
University of Pittsburgh Medical Center