Rationale: We previously reported outcome-associated decreases in muscle energetic status and mitochondrial dysfunction in septic patients with multiorgan failure. We postulate that survivors have a greater ability to maintain or recover normal mitochondrial functionality. Objectives: To determine whether mitochondrial biogenesis, the process promoting mitochondrial capacity, is affected in critically ill patients. Methods: Muscle biopsies were taken from 16 critically ill patients recently admitted to intensive care (average 1-2 d) and from 10 healthy, age-matched patients undergoing elective hip surgery. Measurements and Main Results: Survival, mitochondrial morphology, mitochondrial protein content and enzyme activity, mitochondrial biogenesis factor mRNA, microarray analysis, and phosphorylated (energy) metabolites were determined. Ten of 16 critically ill patients survived intensive care. Mitochondrial size increased with worsening outcome, suggestive of swelling. Respiratory protein subunits and transcripts were depleted in critically ill patients and to a greater extent in nonsurvivors. The mRNA content of peroxisome proliferator-activated receptor g coactivator 1-a (transcriptional coactivator of mitochondrial biogenesis) was only elevated in survivors, as was the mitochondrial oxidative stress protein manganese superoxide dismutase. Eventual survivors demonstrated elevated muscle ATP and a decreased phosphocreatine/ATP ratio. Conclusions: Eventual survivors responded early to critical illness with mitochondrial biogenesis and antioxidant defense responses. These responses may partially counteract mitochondrial protein depletion, helping to maintain functionality and energetic status. Impaired responses, as suggested in nonsurvivors, could increase susceptibility to mitochondrial damage and cellular energetic failure or impede the ability to recover normal function. Clinical trial registered with clinical trials.gov (NCT00187824).

Myocardial function is depressed in sepsis and is an important prognosticator in the human condition. Using echocardiography in a long-term fluid-resuscitated Wistar rat model of faecal peritonitis we investigated whether depressed myocardial function could be detected at an early stage of sepsis and, if so, whether the degree of depression could predict eventual outcome. At 6 h post-insult, a stroke volume <0.17 ml prognosticated 3-day mortality with positive and negative predictive values of 93 and 80%, respectively. Subsequent fluid loading studies demonstrated intrinsic myocardial depression with poor-prognosis animals tolerating less fluid than either good-prognosis or sham-operated animals. Cardiac gene expression analysis at 6 h detected 527 transcripts significantly up- or down-regulated by the septic process, including genes related to inflammatory and cell cycle pathways. Predicted mortality was associated with significant differences in transcripts of genes expressing proteins related to the TLR2/MyD88 (Toll-like receptor 2/myeloid differentiation factor 88) and JAK/STAT (Janus kinase/signal transducer and activator of transcription) inflammatory pathways, β-adrenergic signalling and intracellular calcium cycling. Our findings highlight the presence of myocardial depression in early sepsis and its prognostic significance. Transcriptomic analysis in heart tissue identified changes in signalling pathways that correlated with clinical dysfunction. These pathways merit further study to both better understand and potentially modify the disease process.

Development of a dysregulated immune response discriminates sepsis from uncomplicated infection. Currently used biomarkers fail to describe simultaneously occurring pro- and anti-inflammatory responses potentially amenable to therapy.Marker candidates were screened by microarray and, after transfer to a platform allowing point-of-care testing, validated in a confirmation set of 246 medical and surgical patients. We identified up-regulated pathways reflecting innate effector mechanisms, while down-regulated pathways related to adaptive lymphocyte functions. A panel of markers composed of three up- (Toll-like receptor 5; Protectin; Clusterin) and 4 down-regulated transcripts (Fibrinogen-like 2; Interleukin-7 receptor; Major histocompatibility complex class II, DP alpha1; Carboxypeptidase, vitellogenic-like) described the magnitude of immune alterations. The created gene expression score was significantly greater in patients with definite as well as with possible/probable infection than with no infection (median (Q25/Q75): 80 (60/101)) and 81 (58/97 vs. 49 (27/66), AUC-ROC = 0.812 (95%-CI 0.755–0.869), p < 0.0001). Down-regulated lymphocyte markers were associated with prognosis with good sensitivity but limited specificity.Quantifying systemic inflammation by assessment of both pro- and anti-inflammatory innate and adaptive immune responses provides a novel option to identify patients-at-risk and may facilitate immune interventions in sepsis.

TNFα has been implicated in the pathogenesis of various inflammatory diseases. Different strategies to inhibit TNFα in patients with sepsis and chronic inflammatory conditions have shown contrasting outcomes. Although TNFα inhibitors are widely used in clinical practice, the impact of TNFα antagonism on white blood cell gene expression profiles during acute inflammation in humans in vivo has not been assessed. We here leveraged the established model of human endotoxemia to examine the effect of the TNFα antagonist, etanercept, on the genome-wide transcriptional responses in circulating leukocytes induced by intravenous LPS administration in male subjects. Etanercept pre-treatment resulted in a markedly dampened transcriptional response to LPS. Gene co-expression network analysis revealed this LPS-induced transcriptome can be categorized as TNFα responsive and non-responsive modules. Highly significant TNFα responsive modules include NF-kB signaling, antiviral responses and T-cell mediated responses. Within these TNFα responsive modules we delineate fundamental genes involved in epigenetic modifications, transcriptional initiation and elongation. Thus, we provide comprehensive information about molecular pathways that might be targeted by therapeutic interventions that seek to inhibit TNFα activity during human inflammatory diseases.

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