Zhi-Yong Peng

Effects of hemoadsorption on cytokine removal and short-term survival in septic rats.

Objective:A broad-spectrum immune-regulating therapy could be beneficial in the treatment of sepsis. Our previous studies have shown that a hemoadsorption device (CytoSorb) removes both pro- and anti-inflammatory cytokines and improves survival in experimental endotoxemia. We sought to determine whether hemoadsorption can also be effective in the treatment of sepsis. Design:Randomized controlled laboratory experiment. Setting:University laboratory. Interventions:Rats were subjected to cecal ligation and puncture (CLP) and 20 hrs later were randomized to receive either hemoadsorption or sham treatment using an arterial-venous circuit. Hemoadsorption was accomplished using a cartridge containing Cytosorb beads. Blood was drawn for cytokine measurements and mean arterial pressure (MAP) was continuously monitored. Cytokines were measured via multiplex bead immunoassays. Survival time was observed for 9 hours after the intervention and assessed by Kaplan–Meier statistics. The overall survival in each group was compared using Fishers exact test. Finally, we used a Cox proportional-hazards model to examine the effects of cytokine removal on survival time. Measurements and Main Results:Baseline plasma cytokine concentrations and MAP were similar between hemoadsorption and sham-treated groups. However, the concentrations of tumor necrosis factor, interleukin (IL)-1β, IL-6, and IL-10 were significantly lower after hemoadsorption compared to the sham group. Six hours after treatment ended, IL-6 and IL-10 concentrations were still lower in hemoadsorption group. MAP was significantly better in hemoadsorption compared to sham-treated animals (p < .05). Finally, mean survival time was significantly longer (720 vs. 381 min, p < .05, Mann–Whitney test), and overall survival was significantly better (11/17 vs. 2/16, p < .01) with hemoadsorption compared to sham. Combined reduction in both IL-6 and IL-10 was associated with a significantly decreased risk of death (hazard ratio, .11, p = .005). Conclusion:Hemoadsorption reduced circulating cytokines, improved MAP, and resulted in better short-term survival in CLP-induced septic rats.

Pathophysiology of Acute Kidney Injury: A New Perspective

Acute kidney injury (AKI) in critically ill patients is a devastating illness associated with prolonged hospital stay and high mortality. Limited progress has been made in the field of AKI, and its treatment using renal replacement therapy, at best, only provides partial renal support. Ischemia-reperfusion rodent AKI models do not resemble human renal injury and the absence of renal biopsy data limits our understanding of the pathophysiology of human AKI. However, laboratory and clinical evidence suggests that the inflammatory milieu leads to dysfunction of renal cells and this may be the key factor leading to AKI. Cells in injured tissues release immunological danger signals or danger-associated molecular pattern molecules which communicate with remote organs including the kidney, where they activate dendritic cells and T cells and thus initiate inflammation. Once the initial insult has passed, tubular epithelial cells undergo dedifferentiation, reacquire progenitorial ability to proliferate, migrate, and redifferentiate into mature intrinsic cells. Dissonance of mediator secretion and cell responses may lead to persistent injury and de novo chronic kidney disease. A number of soluble mediators including transforming growth factor-beta (TGF-beta) initiate a variety of pathophysiological processes at the beginning of kidney injury. TGF-beta also plays a fundamental role in cell proliferation and interstitial fibrosis in later phases. The renin-angiotensin-aldosterone system, especially angiotensin II, contributes to kidney injury through the angiotensin II type 1 receptor, TGF-beta receptor Smad and epidermal growth factor receptor by affecting general angiostasis and vascular remodeling, indirectly modulating inflammation and cell reactions. We review the pathophysiology of AKI in light of new information regarding renal injury and repair.

The influence of macrophage migration inhibitory factor gene polymorphisms on outcome from community-acquired pneumonia

The cytokine, macrophage migration inhibitory factor (MIF), is encoded in a functionally polymorphic locus and subjects with high‐expression MIF alleles are at an increased risk of inflammatory disease. Severe sepsis is the leading cause of death in intensive care units, and the prevailing hypothesis is that an excessive innate response contributes to its pathogenesis. To assess if MIF alleles influence the clinical course of infection, we conducted a case‐ control study to assess susceptibility and a parallel inception cohort study of community‐acquired pneumonia (CAP) to assess risk of severe sepsis and 90‐d mortality. Two distinct polymorphisms in the MIF promoter were analyzed: a G/C transition at —173 and a CATT repeat at —794. The frequency of both polymorphisms was similar in the CAP cohort (n=1739) and controls (n=639);however, the 90‐d mortality was lower for the high‐expression C allele (P=0.003). This association remained significant after adjusting for demographics, comorbid conditions, and disease severity score [hazard ratio = 0.64 (0.44‐0.91), P=0.01]. The hazard ratio was similar in different geographic subcohorts, and the association remained significant after adjusting for false discovery. These data indicate that polymorphisms associated with higher MIF expression may have a beneficial effect in community‐acquired pneumonia.— Yende, S., Angus, D. C., Kong, L., Kel‐ lum, J. A., Weissfeld, L., Ferrell, R., Finegold, D., Carter, M., Leng, L., Peng, Z.‐Y., Bucala, R. The influence of macrophage migration inhibitory factor gene polymorphisms on outcome from communityacquired pneumonia. FASEB J. 23, 2403–2411 (2009)

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 72 h 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.

Blood Purification in Sepsis: A New Paradigm

Sepsis is one of the main causes of death in critically ill patients. The pathophysiology of sepsis is complex and not completely understood. The proinflammatory and anti-inflammatory response leads to cell and organ dysfunction and, in many cases, death. Thus, the goal of the intervention is to restore the homeostasis of circulating mediators rather than to inhibit selectively the proinflammatory or anti-inflammatory mediators. Blood purification has been reported to remove a wide array of inflammatory mediators. The effects are broad-spectrum and auto-regulating. Blood purification has also been demonstrated to restore immune function through improving antigen-presenting capability, adjusting leukocyte recruitment, oxidative burst and phagocytosis, and improving leukocyte responsiveness. A great deal of work has to be done in order to find and optimize the best extracorporeal blood purification therapy for sepsis. New devices specifically target the pathophysiological mechanisms involved in these conditions. High-volume hemofiltration, hemoadsorption, coupled plasma filtration adsorption, and high cutoff membrane are now being tested in septic patients. Preliminary data indicate the feasibility of these modified techniques in sepsis. Their impact on patient prognosis, however, still needs proof by large randomized clinical trials. Finally, the emerging paradigm of sepsis-induced immune suppression provides additional rationale for the development of extracorporeal blood purification therapy for sepsis.

Hemoadsorption reprograms inflammation in experimental gram-negative septic peritonitis: insights from in vivo and in silico studies.

Improper compartmentalization of the inflammatory response leads to systemic inflammation in sepsis. Hemoadsorption (HA) is an emerging approach to modulate sepsis-induced inflammation. We sought to define the effects of HA on inflammatory compartmentalization in Escherichia coli-induced fibrin peritonitis in rats. Hypothesis: HA both reprograms and recompartmentalizes inflammation in sepsis. Sprague Dawley male rats were subjected to E. coli peritonitis and, after 24 h, were randomized to HA or sham treatment (sepsis alone). Venous blood samples collected at 0, 1, 3 and 6 h (that is, 24–30 h of total experimental sepsis), and peritoneal samples collected at 0 and 6 h, were assayed for 14 cytokines along with NO2−/NO3−. Bacterial counts were assessed in the peritoneal fluid at 0 and 6 h. Plasma tumor necrosis factor (TNF)-α, interleukin (IL)-6, CXCL-1, and CCL2 were significantly reduced in HA versus sham. Principal component analysis (PCA) suggested that inflammation in sham was driven by IL-6 and TNF-α, whereas HA-associated inflammation was driven primarily by TNF-α, CXCL-1, IL-10 and CCL2. Whereas peritoneal bacterial counts, plasma aspartate transaminase levels and peritoneal IL-5, IL-6, IL-18, interferon (IFN)-γ and NO2−/NO3− were significantly lower, both CXCL-1 and CCL2 as well as the peritoneal-to-plasma ratios of TNF-α, CXCL-1 and CCL2 were significantly higher in HA versus sham, suggesting that HA-induced inflammatory recompartmentalization leads to the different inflammatory drivers discerned in part by PCA. In conclusion, this study demonstrates the utility of combined in vivo/in silico methods and suggests that HA exerts differential effects on mediator gradients between local and systemic compartments that ultimately benefit the host.

Bactericidal Antibiotics temporarily increase inflammation and worsen acute kidney injury in experimental sepsis

Objective: To explore the relationships among bactericidal antimicrobial treatment of sepsis, inflammatory response, severity of acute kidney injury, and outcomes. Design: Controlled laboratory experiment. Setting: University laboratory. Interventions: Sepsis was induced by cecal ligation and puncture in 52 rats and was treated with either bactericidal antibiotics (ampicillin/sulbactam) or placebo (saline). Serial blood specimens were obtained after cecal ligation and puncture for serum creatinine, interleukin-6, and neutrophil gelatinase-associated lipocalin concentrations. RIFLE (Risk, Injury, Failure, Loss, End-stage kidney disease) criteria were used to assess severity of acute kidney injury. All animals were observed for survival up to 1 wk. In a separate experiment, six healthy animals were given antibiotics and renal function was assessed. Another 12 animals were euthanized 2 days after laparotomy for kidney histology. Measurements and Main Results: Survival in the placebo group was 50% compared with 81.8% in the antibiotic group (p < .05). Most animals (93%) without antibiotics developed acute kidney injury, of which 39% exhibited greater than a threefold rise in serum creatinine (RIFLE-F). Furthermore, survival decreased as acute kidney injury severity increased. Surprisingly, all antibiotic-treated animals developed acute kidney injury, of which 68.6% reached RIFLE-F. However, renal dysfunction was less persistent in these animals. Patterns of plasma interleukin-6 were similar to creatinine with higher concentrations seen earlier in antibiotic-treated animals but with faster resolution. Interleukin-6 concentration at 24 hrs was independently associated with the development of RIFLE-F. Histologic findings were consistent with functional parameters showing that antibiotics worsened acute kidney injury. Conclusion: In polymicrobial sepsis, bactericidal antibiotics resulted in more inflammation and more severe acute kidney injury. However, resolution of inflammation and acute kidney injury was faster with antibiotics and correlated best with survival. These results suggest that transient worsening of renal function may be an expected consequence of sepsis therapy. These findings also question the value of peak severity of acute kidney injury as a primary end point and suggest that resolution of acute kidney injury may be more appropriate.

N-acetylcysteine does not prevent hepatorenal ischaemia–reperfusion injury in patients undergoing orthotopic liver transplantation

BACKGROUND Glutathione (GSH) acts as a free radical scavenger that may be helpful in preventing reperfusion injury. N-acetylcysteine (NAC) replenishes GSH stores. The aims of this study were to evaluate the efficacy of NAC in improving liver graft performance and reducing the incidence of post-operative acute kidney injury (AKI). METHODS Our study was a randomized, double-blind, placebo-controlled trial of 100 patients; 50 received placebo and 50 received a loading dose of 140 mg/kg of intravenous (IV) NAC over 1 h followed by 70 mg/kg IV repeated every 4 h for a total of 12 doses. Both groups were followed up for 1 year post-orthotopic liver transplant (OLT). We recorded liver function tests, renal function tests, graft survival, patient survival, plasma GSH and duration of hospital and ICU stay. In addition to serum creatinine (SCr) levels, we analysed cystatin C and beta-trace as independent measures of glomerular filtration. All clinical data were recorded daily for the first week after the surgery, then on Days 14, 21, 30, 90 and 180 and at the end of the first year. RESULTS IV NAC did not affect survival, graft function or risk of AKI. However, GSH levels were highly variable with only 50% of patients receiving NAC exhibiting increased levels and fewer patients developed AKI when GSH levels were increased. Additional risk factors for AKI in the post-transplant period were female gender (P = 0.05), increased baseline serum bilirubin (P = 0.004) and increased baseline SCr levels (P = 0.02). CONCLUSIONS IV NAC was not effective in reducing renal or hepatic injury in the setting of liver transplantation. The dose and duration of NAC used, though higher than most renal protection studies, may have been ineffective for raising GSH levels in some patients.