Effects of hyperglycemia and insulin therapy on outcome in a hyperglycemic septic model of critical illness.

BACKGROUND: The effects of hyperglycemia and insulin therapy on septic outcome have not been well studied. METHODS: Septic hyperglycemia was induced by infusion of TPN (254 kcal/kg x d) immediately following cecal ligation and puncture (CLP) surgery in rats. Animals (N = 109) were monitored for blood glucose and followed for survival for 4 days. Separate cohorts (N = 36) were sacrificed at 22 hours post-CLP and analyzed for cytokines/chemokines, hormones, and organ damage markers. The effects of insulin treatment on 4 day survival were also examined (N = 60). RESULTS: Hyperglycemic septic animals had significantly higher blood glucose (p < 0.0001), plasma proinflammatory cytokine levels, serum organ damage markers (p < 0.05) and reduced mean survival time (p < 0.001). Insulin treatment (2 IU/kg/hr) resulted in significantly lower blood glucose (p < 0.01) and improved 4 day survival (p < 0.03). CONCLUSIONS: Hyperglycemia is associated with greater morbidity and mortality in sepsis. Insulin therapy significantly improved survival suggesting that management of hyperglycemia with insulin may improve outcome in septic patients.

FoxA2 involvement in suppression of protein C, an outcome predictor in experimental sepsis.

Low levels of protein C (PC) predict outcome as early as 10 h after insult in a rat polymicrobial sepsis model and were associated with suppression of PC mRNA, upstream transcription factor FoxA2, and cofactor hepatocyte nuclear factor 6 (HNF6). Small interfering RNA suppression of FoxA2 in isolated hepatocytes demonstrated regulation of both its cofactor HNF6 and PC. Our data suggest that reduced FoxA2 may be important in the suppression of PC and resulting poor outcome in sepsis.

Cecal ligation and puncture with total parenteral nutrition: a clinically relevant model of the metabolic, hormonal, and inflammatory dysfunction associated with critical illness.

BACKGROUND: Standard rat cecal ligation and puncture (CLP) results in only transient hyperglycemia, making an examination of the effects of glucoregulatory agents, such as insulin, on the morbidity and mortality of CLP problematic. Accordingly, we sought to develop a model of rat CLP with prolonged hyperglycemia through continuous infusion of total parenteral nutrition (TPN) post CLP. MATERIALS AND METHODS: Polyethylene catheters were implanted into the femoral vein of female Sprague Dawley rats (245-265 g) which were subsequently subjected to CLP. TPN was initiated at different intervals following CLP, and mortality, bacteremia, blood glucose, hormonal, and inflammatory responses were monitored. RESULTS: Without TPN, CLP resulted in significantly lower blood glucose at 22 h post CLP. In contrast, CLP rats receiving TPN exhibited significant prolonged hyperglycemia that was responsive to insulin treatment. Mortality and hyperglycemia tended to increase with puncture size in CLP TPN rats, with early initiation of TPN leading to poorer outcome. There were time-dependent differences in bacteremia and mortality based on time of TPN initiation. Levels of insulin, leptin, and glucagon were significantly elevated in CLP TPN rats, as were many inflammatory markers. Organ damage was evident as early as 12 h post CLP and blood cell kinetics indicated significantly depressed neutrophil and lymphocyte counts. CONCLUSIONS: Our results indicate that addition of TPN to CLP provides a clinically relevant animal model of critical illness with associated hyperglycemia that may provide utility for the testing of glucoregulatory and other therapeutic modalities.

Evaluation of protein C and other biomarkers as predictors of mortality in a rat cecal ligation and puncture model of sepsis.

OBJECTIVE: To evaluate protein C and other factors associated with the septic response as predictors of mortality in a clinically relevant animal model of sepsis. DESIGN: Laboratory investigation. SETTING: Eli Lilly and Company discovery research laboratory. SUBJECTS: Forty female Sprague Dawley rats weighing 245-265 g. INTERVENTIONS: Polyethylene catheters were surgically implanted into the femoral vein and sepsis was induced by cecal ligation and puncture (CLP). A solution of 5% dextrose in 0.9 % saline was continuously infused via femoral catheters immediately following surgery. Blood sampling was done before surgery and at 6 and 20 hrs after surgery. Rats were then monitored for survival out to 4 days. MEASUREMENTS AND MAIN RESULTS: Blood collections were used to measure blood glucose, bacteremia, plasma protein C, D-dimer, hormones, chemokines, cytokines, and myoglobin (as a marker of organ damage). Mortality was categorized into three groups: early death (before 30 hrs post-CLP), late death (after 30 hrs post-CLP), and survivors (96 hrs post-CLP). Compared with survivors, early death rats had statistically significant differences in 30 variables indicative of severe inflammation, coagulopathy, and muscle damage including less bacterial clearance, hypoglycemia, lower plasma protein C, higher plasma D dimer, higher plasma cytokine/ chemokines, and higher plasma myoglobin concentrations. Twenty variables had a moderate to strong correlation with time of death. Receiver operator characteristic curves generated from a simple logistic regression model indicated that KC and macrophage inflammatory protein-2, rodent homologues of the human growth related oncogene CXC chemokine family, and protein C were the best predictors of mortality in this model. CONCLUSIONS: The data from this study indicate that an early decrease in protein C concentration predicts poor outcome in a rat sepsis model. The data further indicate that increases in the CXC chemokines macrophage inflammatory protein-2 and KC precede poor outcome.