A. W. Bacon1, A. D’Alessandro1, A. L. Slaughter1, H. B. Moore1, M. Fragoso1, C. Silliman1,3, A. Banerjee1, E. E. Moore1,2 1University Of Colorado Denver,Dept Of Surgery,Aurora, CO, USA 2Denver Health Medical Center,Dept Of Surgery,Aurora, CO, USA 3Children’s Hospital Colorado,Aurora, CO, USA
Introduction: Post-shock mesenteric lymph (PSML) is a known mediator of the development of acute lung injury (ALI). We have previously shown that PSML contains a distinct proteome from that of plasma whose constituents may potentiate the development of ALI. However, recent advances in mass-spectrometry-based biochemical analysis have prompted ongoing documentation and quantification of the plasma metabolome following life-threatening injury. However, the PSML metabolome and its pulmonary sequela remain unexamined. Thus, we hypothesized that PSML contains a specific and distinct biochemical millieu that may potentiate the development of ALI.
Methods: Male Sprague-Dawley rats (n=4 per group) underwent tracheostomy, femoral artery cannulation and laparotomy with mesenteric duct cannulation followed by profound hemorrhagic shock (MAP = 27 ± 2 mmHg for 30 min) followed by partial resuscitation (MAP > 60 mmHg for 30 min). Pre- and post-shock plasma and lymph and bronchoalveolar lavage fluid (BALF) were collected for analysis. Control and sham shock (T/SS) animals were employed. Select metabolites were assayed via ultra-high performance liquid chromatography-mass spectrometry. Results are expressed as means ± SEM and compared to controls via Dunnett's test (p < 0.05 threshold).
Results: Trauma alone had no significant effect on the systemic metabolome. Trauma and hemorrhagic shock (T/HS) resulted in fluid-specific hyperglycemia, accumulation of lactate, succinate and malate, oxidized and reduced glutathione and uric acid when compared to baseline controls. T/HS with mesenteric lymph diversion (MLD) revealed a 5-fold increase in BALF succinate and 4-fold increase in BALF urate when compared to the T/HS cohort (Fig 1).
Conclusion: Trauma and hemorrhagic shock results in systemic metabolic aberration. Post-shock plasma and PSML exhibit a qualitatively and quantitatively specific pathologic metabolic profile that ultimately perturbs pulmonary metabolism. These changes were consistent with hypoxemic metabolism in the ischemic gut, including: hyperglycemia, accumulation of anaerobic and key TCA-cycle metabolites, dysregulated redox homeostasis and nitrogen catabolism suggesting hypoxic uncoupling of the electron transport chain, accumulation of reactive oxygen species (ROS) and anapleurosis. Interestingly, MLD had a profound and unexpected effect on BALF succinate, a known IL-1ß activator, and urate, a potential ROS scavenger, suggesting PSML-associated ALI may result from inhibition of the potentially beneficial immune effects of these small molecular messengers. As such, additional study is warranted to elucidate the mechanisms responsible for post-shock metabolopathy and its role in the development of ALI.
