Mitochondrial biogenesis restores oxidative metabolism during Staphylococcus aureus sepsis.
BACKGROUND
The extent, timing, and significance of mitochondrial injury and recovery in bacterial sepsis are poorly characterized, although oxidative and nitrosative mitochondrial damage have been implicated in the development of organ failure.


OBJECTIVE
To define the relationships between mitochondrial biogenesis, oxidative metabolism, and recovery from Staphylococcus aureus sepsis.


METHODS
We developed a murine model of fibrin clot peritonitis, using S. aureus. The model yielded dose-dependent decreases in survival and resting energy expenditure, allowing us to study recovery from sublethal sepsis.


RESULTS
Peritonitis caused by 10(6) colony-forming units of S. aureus induced a low tumor necrosis factor-alpha state and minimal hepatic cell death, but activated prosurvival protein kinase A, B, and C sequentially over 3 days. Basal metabolism by indirect calorimetry was depressed because of selective mitochondrial oxidative stress and subsequent loss of mitochondrial DNA copy number. During recovery, mitochondrial biogenesis was strongly activated by regulated expression of the requisite nuclear respiratory factors 1 and 2 and the coactivator peroxisome proliferator-activated receptor gamma coactivator-1alpha, as well as by repression of the biogenesis suppressor nuclear receptor interacting protein-140. Biogenesis reconstituted mitochondrial DNA copy number and transcription, and restored basal metabolism without significant hepatocellular proliferation. These events dramatically increased hepatic mitochondrial density in transgenic mice expressing mitochondrially targeted green fluorescent protein.


CONCLUSIONS
This is the first demonstration that mitochondrial biogenesis restores oxidative metabolism in bacterial sepsis and is therefore an early and important prosurvival factor.
Haden
Douglas W
DW
Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA. dhaden75@yahoo.com
Suliman
Hagir B
HB
Carraway
Martha Sue
MS
Welty-Wolf
Karen E
KE
Ali
Abdelwahid S
AS
Shitara
Hiroshi
H
Yonekawa
Hiromichi
H
Piantadosi
Claude A
CA
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D001481:Basal Metabolism; D004195:Disease Models, Animal; D051268:GA-Binding Protein Transcription Factor / Q000378:metabolism; D022781:Hepatocytes / Q000473:pathology; D008099:Liver / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008928:Mitochondria / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D000078723:Nuclear Receptor Interacting Protein 1; D051266:Nuclear Respiratory Factor 1 / Q000378:metabolism; D018384:Oxidative Stress; D010538:Peritonitis / Q000382:microbiology; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011494:Protein Kinases / Q000096:biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D018805:Sepsis / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000472:pathogenicity*; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors
D048868:Adaptor Proteins, Signal Transducing; D051268:GA-Binding Protein Transcription Factor; D009687:Nuclear Proteins; D000078723:Nuclear Receptor Interacting Protein 1; D051266:Nuclear Respiratory Factor 1; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D011494:Protein Kinases