PR002492 (Project)

Description:Sepsis, killing 11 million people yearly, is associated with increased lactate production - a metabolite mechanistically linked to mortality - complicating glucose administration in sepsis. To understand the mechanism behind hyperlactatemia, we applied the cecal ligation and puncture (CLP) model and studied all pyruvate processing routes in liver mitochondria during acute sepsis. Our data suggest that mitochondrial pyruvate-driven respiration is nearly nonexistent in sepsis, not due to insufficient pyruvate uptake or carboxylation but due to a dysfunctional pyruvate dehydrogenase complex (PDC). Septic mitochondria compensate by glutamate-mediated TCA anaplerosis, simultaneously converting some pyruvate into alanine via enhanced mitochondrial glutamic pyruvate transaminase (GPT2) activity. Notably, PDC dysfunction is not caused by PDC inactivation per se but by a shortage of its cofactor, thiamine pyrophosphate (TPP). TPP supplementation restores pyruvate oxidation both ex vivo and in vivo and protects mice from sepsis. TPP also allows safe glucose administration in mice, leading to a novel, robust TPP-plus-glucose therapy.