Feihu Zhou

Blood Purification and Mortality in Sepsis: A Meta-analysis of Randomized Trials

Objectives:Although blood purification improves outcomes in animal studies of sepsis, results of clinical trials have been mixed. We conducted a systematic review and meta-analysis of randomized trials to determine the association between various blood purification techniques and all-cause mortality in humans with sepsis. Data Sources:We searched for relevant studies in MEDLINE, EMBASE, and the Cochrane Library database from January 1966 to May 2012. Study Selection:Inclusion required a diagnosis of sepsis and comparison of blood purification techniques including hemofiltration, hemoperfusion, plasma exchange, or hemodialysis with no blood purification (control group). Data Extraction:Two authors independently selected studies and extracted data. Summary statistics, risk ratios, and CIs were calculated using random-effects modeling. Study quality was assessed using Jadad score, and publication bias was assessed using funnel plots and Egger’s statistic. Data Synthesis:Overall, blood purification decreased mortality compared with no blood purification (35.7% vs 50.1%; risk ratio, 0.69 [95% CI, 0.56–0.84]; p < 0.001; 16 trials, n = 827). However, these results were driven mainly by hemoperfusion (risk ratio, 0.63 [95% CI, 0.50–0.80]; p < 0.001; 10 trials, n = 557) and plasma exchange (risk ratio, 0.63 [95% CI, 0.42–0.96]; p = 0.03; two trials, n = 128). Pooling of all trials of blood purification for treatment of sepsis was no longer associated with lower mortality (risk ratio, 0.89 [95% CI, 0.71–1.13]; p = 0.36; eight trials, n = 457) after excluding trials using polymyxin B hemoperfusion. Conclusions:Blood purification techniques including hemoperfusion, plasma exchange, and hemofiltration with hemoperfusion were associated with lower mortality in patients with sepsis. These results were mainly influenced by studies using polymyxin B hemoperfusion from Japan.

Acute removal of common sepsis mediators does not explain the effects of extracorporeal blood purification in experimental sepsis

The effect of extracorporeal blood purification on clinical outcomes in sepsis is assumed to be related to modulation of plasma cytokine concentrations. To test this hypothesis directly, we treated rats that had a cecal ligation followed by puncture (a standard model of sepsis) with a modest dose of extracorporeal blood purification that did not result in acute changes in a panel of common cytokines associated with inflammation (TNF-α, IL-1β, IL-6, and IL-10). Pre- and immediate post-treatment levels of these cytokines were unchanged compared to the sham therapy of extracorporeal circulation without blood purifying sorbent. The overall survival to 7 days, however, was significantly better in animals that received extracorporeal blood purification compared to those with a sham procedure. This panel of common plasma cytokines along with alanine aminotransferase and creatinine was significantly lower 72u2009h following extracorporeal blood purification compared to sham-treated rats. Thus, the effects of this procedure on organ function and survival do not appear to be due solely to immediate changes in the usual measured circulating cytokines. These results may have important implications for the design and conduct of future trials in sepsis including defining alternative targets for extracorporeal blood purification and other therapies.

Effects of fluid resuscitation with 0.9% saline versus a balanced electrolyte solution on acute kidney injury in a rat model of sepsis*.

Objective:To compare the acute effects of 0.9% saline versus a balanced electrolyte solution on acute kidney injury in a rat model of sepsis. Design:Controlled laboratory experiment. Setting:University laboratory. Subjects:Sixty adult, male Sprague-Dawley rats. Interventions:We induced sepsis by cecal ligation and puncture and randomized animals to receive fluid resuscitation with either 0.9% saline or Plasma-Lyte solution for 4 hours after 18 hours of cecal ligation and puncture (10 mL/kg in the first hour and 5 mL/kg in the next 3 hr). Blood and urine specimens were obtained from baseline, 18 hours after cecal ligation and puncture, immediately after 4 hours fluid resuscitation, and 24 hours later. We measured blood gas, plasma electrolytes, creatinine, interleukin-6, cystatin C, and neutrophil gelatinase-associated lipocalin concentrations. We also analyzed urine for cystatin C and neutrophil gelatinase-associated lipocalin. We used Risk, Injury, Failure, Loss and End-stage criteria for creatinine to assess severity of acute kidney injury. We observed all animals for survival up to 1 day after resuscitation. Surviving animals were killed for kidney histology. Finally, we carried out an identical study in 12 healthy animals. Measurements and Main Results:Compared with Plasma-Lyte, 0.9% saline resuscitation resulted in significantly greater blood chloride concentrations (p < 0.05) and significantly decreased pH and base excess. Acute kidney injury severity measured by RIFLE criteria was increased with 0.9% saline compared with Plasma-Lyte resuscitation (p < 0.05), and these results were consistent with kidney histology and biomarkers of acute kidney injury. Twenty-four-hour survival favored Plasma-Lyte resuscitation (76.6% vs 53.3%; p = 0.03). Finally, in healthy animals, we found no differences between fluids and no evidence of acute kidney injury. Conclusion:Volume resuscitation with Plasma-Lyte resulted in less acidosis and less kidney injury and improved short-term survival when compared with 0.9% saline in this experimental animal model of sepsis.

Modulation of chemokine gradients by apheresis redirects leukocyte trafficking to different compartments during sepsis, studies in a rat model

IntroductionPrior work suggests that leukocyte trafficking is determined by local chemokine gradients between the nidus of infection and the plasma. We recently demonstrated that therapeutic apheresis can alter immune mediator concentrations in the plasma, protect against organ injury, and improve survival. Here we aimed to determine whether the removal of chemokines from the plasma by apheresis in experimental peritonitis changes chemokine gradients and subsequently enhances leukocyte localization into the infected compartment, and away from healthy tissues.MethodsIn total, 76 male adult Sprague–Dawley rats weighing 400xa0g to 600xa0g were included in this study. Eighteen hours after inducing sepsis by cecal ligation and puncture, we randomized these rats to apheresis or sham treatment for 4xa0hours. Cytokines, chemokines, and leukocyte counts from blood, peritoneal cavity, and lung were measured. In a separate experiment, we labeled neutrophils from septic donor animals and injected them into either apheresis or sham-treated animals. All numeric data with normal distributions were compared with one-way analysis of variance, and numeric data not normally distributed were compared with the Mann–Whitney U test.ResultsApheresis significantly removed plasma cytokines and chemokines, increased peritoneal fluid-to-blood chemokine (C-X-C motif ligand 1, ligand 2, and C-C motif ligand 2) ratios, and decreased bronchoalveolar lavage fluid-to-blood chemokine ratios, resulting in enhanced leukocyte recruitment into the peritoneal cavity and improved bacterial clearance, but decreased recruitment into the lung. Apheresis also reduced myeloperoxidase activity and histologic injury in the lung, liver, and kidney. These Labeled donor neutrophils exhibited decreased localization in the lung when infused into apheresis-treated animals.ConclusionsOur results support the concept of chemokine gradient control of leukocyte trafficking and demonstrate the efficacy of apheresis to target this mechanism and reduce leukocyte infiltration into the lung.

Cross-species validation of cell cycle arrest markers for acute kidney injury in the rat during sepsis

BackgroundThe recent discovery of cell cycle arrest biomarkers, tissue inhibitor of metalloproteinases (TIMP)-2 and insulin-like growth factor binding protein 7 (IGFBP7), has led to a newly available clinical test for acute kidney injury. The performance of these markers in preclinical studies has not been established. Therefore, we sought to evaluate the performance of TIMP-2 and IGFBP7 in rats undergoing cecal ligation and puncture.MethodsIn this secondary analysis, we analyzed banked urine samples from 60 Sprague-Dawley rats undergoing cecal ligation and puncture (CLP). Samples were obtained from baseline, 18xa0h after CLP, at the end of fluid resuscitation (22xa0h after CLP), and again 24xa0h later. We measured TIMP-2 and IGFBP7 and compared the results to acute kidney injury by RIFLE criteria for creatinine using area under the receiver operating characteristic curve (AUC). The primary endpoint was moderate-to-severe acute kidney injury (AKI) (I or F criteria), and the primary time point was immediately after fluid resuscitation. Secondary outcomes included mortality and comparisons with other biomarkers: cystatin C and neutrophil gelatinase-associated lipocalin (NGAL) in both urine and plasma.ResultsAfter fluid resuscitation, urine [TIMP-2] and [IGFBP7] were significantly higher in animals developing moderate-to-severe AKI (pu2009=u20090.002 and pu2009=u20090.01). AUC of [TIMP-2]·[IGFBP7] for AKI was 0.89 (95xa0% CI 0.80–0.98). By contrast, the next best AUC was seen with plasma cystatin C (0.78; 95xa0% CI 0.65–0.90). [TIMP-2]·[IGFBP7] also predicted mortality (AUC 0.69; 95xa0% CI 0.53–0.85).ConclusionsIn this experimental model of sepsis in the rat, cell cycle arrest biomarkers TIMP-2 and IGFBP7 are valid predictors of acute kidney injury.

The anti-oxidant effects are not the main mechanism for glutamine's protective effects on acute kidney injury in mice.

Acute kidney injury (AKI) is a common problem characterized by an inflammatory response in the kidney and oxidative stress. However, there are no interventions to prevent AKI. Glutamine is an important precursor of glutathione and has also been shown to induce heat shock proteins (HSP). Thus, glutamine may affect both oxidative stress and inflammation. This study was to explore the effects of glutamine pretreatment on nephrotoxic AKI and to investigate the underlying mechanisms. First, the effects of alternate doses of glutamine were compared in CD-1 mice with AKI induced with folic acid intra-peritoneal injection. Then the effects of glutamine quercetin (an HSP inhibitor), and quercetin+glutamine, were compared in the same AKI model. AKI were assessed with plasma creatinine, urine neutrophil gelatinase-associated lipocalin, and renal histology. Inflammatory response was monitored with renal tumor necrosis factor (TNF-α), chemkines (CXCL1 and CCL2) contents, and neutrophil infiltration. Oxidative injury was detected with reduced glutathione, malondialdehyde, and protein thiol. Glutamine provided dose-dependent renal protection. Pretreatment with quercetin, which was showed to inhibit HSP-70 expression, abolished glutamines renal-protective effects. Quercetin also abrogated glutamines beneficial effects on renal TNF-α, chemokines, and neutrophil infiltration. However, quercetin did not affect glutamines anti-oxidative effects. These results suggest that glutamines renal-protective effects are mainly related to its activation of HSP-70, which mitigates inflammatory response, renal neutrophil infiltration and subsequent AKI. Regulating neutrophil infiltration might be a potential therapeutic target for AKI.

Development of venovenous extracorporeal blood purification circuits in rodents for sepsis

BACKGROUNDnUnlike pharmacologic interventions in sepsis, extracorporeal blood purification, which is widely used in septic patients, is not typically studied in experimental rodents. Most of the previous studies have performed extracorporeal blood purification in larger animals and typically use arteriovenous (AV) vascular access. We developed a venovenous (VV) purification model in the rat as an adjunct for the treatment of sepsis.nnnMETHODSnUsing adult male Sprague-Dawley rats, we cannulated the femoral artery or vein and the jugular vein with P50 tubing and created an AV or VV circuit. Blood flow was maintained by arterial pressure in the AV circuit, whereas in the VV circuit the blood flow was regulated using a rotary pump. The safety of this circuit was evaluated using the changes of blood interleukin 6, rectal temperature, and 7-d survival with sham extracorporeal circulation (circuit connection without treatment) compared with the control (without circuit). The main side complications of this VV circuit were compared with those of the AV circuit.nnnRESULTSnThe differences in interleukin 6, body temperature, and cumulative survival were not statistically significant after extracorporeal circulation. The main complications of extracorporeal circulation occurred less often with VV compared with AV therapy: massive bleeding (2.5% versus 15%, P = 0.04); clot formation (2.5% versus 15%, P = 0.04). This VV circuit has been successfully used in different septic rodent models with different techniques (hemoadsorption and hemofiltration).nnnCONCLUSIONSnVV blood purification in a rodent model appears to be effective and is safer than AV circuit.