• Joel Schilling, Ling Lai, Nandakumar Sambandam, Courtney E Dey, Teresa C Leone, and Daniel P Kelly.
• Center for Cardiovascular Research, Department of Medicine, Washington University School of Medicine, St Louis, MO, USA.
• Circ Heart Fail. 2011 Jul 1; 4 (4): 474-82.

BackgroundCurrently, there are no specific therapies available to treat cardiac dysfunction caused by sepsis and other chronic inflammatory conditions. Activation of toll-like receptor 4 (TLR4) by lipopolysaccharide (LPS) is an early event in Gram-negative bacterial sepsis, triggering a robust inflammatory response and changes in metabolism. Peroxisome proliferator-activated receptor-γ coactivator-1 (PGC-1) α and β serve as critical physiological regulators of energy metabolic gene expression in heart.Methods And ResultsInjection of mice with LPS triggered a myocardial fuel switch similar to that of the failing heart: reduced mitochondrial substrate flux and myocyte lipid accumulation. The LPS-induced metabolic changes were associated with diminished ventricular function and suppression of the genes encoding PGC-1α and β, known transcriptional regulators of mitochondrial function. This cascade of events required TLR4 and nuclear factor-κB activation. Restoration of PGC-1β expression in cardiac myocytes in culture and in vivo in mice reversed the gene regulatory, metabolic, and functional derangements triggered by LPS. Interestingly, the effects of PGC-1β overexpression were independent of the upstream inflammatory response, highlighting the potential utility of modulating downstream metabolic derangements in cardiac myocytes as a novel strategy to prevent or treat sepsis-induced heart failure.ConclusionsLPS triggers cardiac energy metabolic reprogramming through suppression of PGC-1 coactivators in the cardiac myocyte. Reactivation of PGC-1β expression can reverse the metabolic and functional derangements caused by LPS-TLR4 activation, identifying the PGC-1 axis as a candidate therapeutic target for sepsis-induced heart failure.

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