Dendrimer-enhanced MRI as a diagnostic and prognostic biomarker of sepsis-induced acute renal failure in aged mice

BACKGROUND: Acute renal failure (ARF) induced by sepsis has a high mortality. In an aged mouse model of sepsis-induced ARF we have previously shown that renal injury occurs before serum creatinine is elevated. Development of a noninvasive biomarker that could diagnose renal dysfunction early in sepsis and monitor the response to therapy would be very valuable. METHODS: We performed magnetic resonance imaging (MRI) with gadolinium-based G4 dendrimer intravenous contrast in a fluid- and antibiotic-treated cecal ligation and puncture (CLP) sepsis model in aged mice. Imaging was also performed in a mouse volume depletion model and in models of ARF induced by ischemia/reperfusion (I/R) and cisplatin. RESULTS: Twenty hours post-CLP, aged mice had a distinct pattern of renal injury using dendrimer-enhanced MRI. This pattern was different from renal injury induced by either cisplatin or I/R. Prerenal azotemia induced by volume depletion was distinguished from sepsis by dendrimer-enhanced MRI. Dendrimer-enhanced MRI detected renal dysfunction 6 hours post-CLP, a time when serum creatinine was still normal. Ethyl pyruvate reversed the renal dysfunction detected by dendrimer-enhanced MRI at 20 hours, but not at 6 hours post-CLP. The appearance of renal dysfunction on dendrimer-enhanced MRI at 6 hours post-CLP predicted the length of survival. CONCLUSION: Dendrimer-enhanced MRI is a novel biomarker that provides information for the early diagnosis, drug responsiveness, and prognosis of sepsis-induced ARF.     

Sepsis-induced organ failure is mediated by different pathways in the kidney and liver: acute renal failure is dependent on MyD88 but not renal cell apoptosis

Toll-like receptors (TLRs) are important in sepsis. Myeloid differentiation factor 88 (MyD88) is a key molecule involved in signal transduction by multiple TLRs. The objective of this study was to investigate the contribution of TLR4 and MyD88 to acute renal failure (ARF) induced by polymicrobial sepsis. Liver dysfunction and apoptosis in the spleen contribute to sepsis severity after cecal ligation and puncture (CLP). Therefore, we also investigated liver injury and splenic apoptosis. We used a mouse model of sepsis-induced ARF using CLP to generate polymicrobial sepsis. Despite fluid and antibiotic resuscitation the mice developed multi-organ failure, including ARF, which resembles human sepsis. We investigated the role of the TLR4 receptor by comparing C3H/HeJ mice (which lack TLR4) with C3H/He0UJ normal controls. The role of MyD88 was investigated by comparing MyD88 knockout mice (MyD88(-/-)) with wild-type controls. Following CLP, mice lacking TLR4 and wild-type mice both developed comparable ARF. However, MyD88(-/-) mice did not develop ARF compared to wild-type controls. In contrast, MyD88(-/-) mice developed liver injury comparable to wild type. After CLP, MyD88(-/-) mice had significantly reduced apoptosis in the spleen compared with wild type. Apoptosis was not detected in the kidney of wild-type or MyD88(-/-) mice after CLP. In summary, ARF induced by polymicrobial sepsis is dependent on MyD88, but not TLR4. The absence of MyD88 dissociates ARF from liver injury; liver injury is MyD88-independent. There was MyD88-dependent apoptosis in the spleen, but no apoptosis in the kidney. MyD88 may be a good drug target for some, but not all, organ dysfunctions following sepsis.     

Interleukin-12 and -18 induce severe liver injury in mice recovered from peritonitis after sublethal endotoxin challenge

BACKGROUND: Postoperative intraabdominal abscess is the major complication after abdominal surgery, and additional infection is often observed and becomes the leading cause of death in septic patients who survive initial resuscitation. Sepsis is initiated and perpetuated by the overzealous systemic production of proinflammatory cytokines-such as tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-12, and IL-18-sometimes resulting in excessive tissue injury and death. The purpose of this study was to assess the correlation between liver and spleen innate cytokine responses and organ dysfunction in sepsis syndrome. METHODS: Peritonitis was induced by cecal ligation and puncture (CLP). All CLP mice survived more than 7 days after the procedure, and serum cytokine (TNF-alpha, IL-12, IL-18, and IL-10) levels peaked 12 hours after CLP; thereafter, they returned to basal levels 7 days after CLP. The mice were injected with a sublethal dose of lipopolysaccharide (LPS) 7 days after CLP. Survival rates, tissue damage, serum cytokine levels, and cytokine production of liver or spleen mononuclear cells (MNCs) were evaluated. RESULTS: All CLP mice died within 6 hours from liver injury 7 days after LPS challenge, but all sham mice survived. IL-12, IL-18, and IFN-gamma levels in supernatants of the liver MNCs stimulated with LPS in CLP mice were significantly higher than those in sham mice 7 days after the procedure. Furthermore, serum IL-12 and IL-18 levels and liver MNCs IL-12, IL-18, and IFN-gamma production were significantly increased in CLP mice compared with sham mice after LPS challenge. Thereafter, effects of anti-IL-12 and/or anti-IL-18 antibody were evaluated in LPS-injected CLP mice. The survival rate of LPS-injected CLP mice treated with both anti-IL-12 and anti-IL-18 antibody was significantly better than that of untreated mice. Furthermore, liver damage was improved. CONCLUSION: Mice recovered from mild peritonitis died of severe liver injury by subsequent injection of a sublethal dose of LPS, and this liver injury was related to the collaborating production of IL-12 and IL-18 by liver MNCs.     

Inhibition of Fas signaling prevents hepatic injury and improves organ blood flow during sepsis

BACKGROUND: Fas/Fas ligand (FasL) system is one of the major pathways triggering apoptosis that has been shown to play an important role in development and pathogenesis of various diseases including liver and gastrointestinal diseases. Studies indicate that FasL deficiency provides a survival advantage in mice subjected to polymicrobial sepsis. However, the extent to which Fas/FasL contributes to organ injury during sepsis is unclear. Thus, the aim of this study was to determine whether in vivo administration of a Fas-signaling inhibitor during sepsis preserves organ function. METHODS: Male adult C3H/HeN mice were subjected to cecal ligation and puncture (CLP) or sham CLP (sham). Twelve hours after CLP, mice received either Fas-receptor fusion protein (FasFP) (200 microg/kg body weight) or the saline vehicle. Twenty-four hours after the onset of sepsis, cardiac output and organ blood flow were measured with radioactive microspheres. Plasma levels of alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase were assessed as indexes of liver damage. Changes in systemic cytokines were measured by enzyme-linked immunosorbent assay. RESULTS. The data indicate that although cardiac output and organ blood flow in the liver, intestine, kidneys, spleen, and heart decreased markedly at 24 hours after CLP, treatment with FasFP maintained the measured hemodynamic parameters and improved hepatic, intestinal, and heart blood flow (P <.05) and partially restored spleen and renal blood flow. Moreover, FasFP treatment markedly attenuated the systemic rise in alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and interleukin 10 (P <.05). CONCLUSIONS: These results not only indicate that there is a role for Fas/FasL-mediated processes in the induction of organ injury but suggest that inhibition of Fas/FasL pathway may represent a novel therapeutic modality for maintaining organ perfusion and preventing liver injury during sepsis.     

Effective renal blood flow and renal energy charge in murine peritonitis

The temporal sequence of physiological derangements preceding acute renal failure (ARF) observed in overwhelming bacterial septicemia remains controversial. In order to examine the relationship of renal circulatory alterations and cellular dysfunction in murine sepsis, effective renal plasma flow (ERPF), renal tissue metabolites, and energy charge ratios were determined in Sprague-Dawley rats at 10 and 20 hours following induction of peritonitis by cecal ligation and perforation (CLP) or cecal manipulation alone (sham). Tissue levels of adenine nucleotides, lactate, and pyruvate were assayed after freeze-clamping kidneys unilaterally followed by enzymatic determinations. Cardiac outputs were determined by thermodilution and ERPF by p-aminohippuric acid (PAH) clearance. Results indicate in this model, despite an increase in cardiac output (P less than 0.05), ERPF was significantly decreased at both 10 hours (P less than; 0.05) and 20 hours (P less than 0.01) following induction of peritonitis. Further, although tissue pyruvate/lactate ratios showed significant decreases by 10 hours (P less than 0.05), diminished energy charge ratios were not observed until 20 hours following septic insult. These findings support the hypothesis of diminished renal perfusion as contributory and antecedent to cellular dysfunction in septicemic ARF.     

Differential alterations in systemic and regional oxygen delivery and consumption during the early and late stages of sepsis.

BACKGROUND: Studies have indicated that regional changes in oxygen utilization during sepsis cannot be predicted from the changes in the whole body oxygen delivery (DO2) and consumption (VO2). The aim of this study, therefore, was to determine whether differential alterations in systemic and regional DO2 and VO2 occur during the early and late stages of sepsis. METHODS: Adult male Sprague-Dawley rats were subjected to sepsis by cecal ligation and puncture (CLP). At 5 hours (i.e., the early, hyperdynamic phase of sepsis) or 20 hours (i.e., the late, hypodynamic phase) after CLP, cardiac output, and organ blood flow were measured by radioactive microspheres. Systemic and regional DO2 and VO2 were determined and plasma levels of lactate were measured. RESULTS: Cardiac output and blood flow to the liver, small intestine, and kidneys increased at 5 hours and decreased at 20 hours after CLP. Although both systemic DO2 and VO2 increased at 5 hours after CLP, systemic DO2 but not VO2 decreased at 20 hours. At 5 hours after CLP, intestinal and renal DO2 increased. However, DO2 in all the tested organs decreased at 20 hours after CLP. VO2 increased in the liver, small intestine, and kidneys at 5 hours after CLP but decreased only in the liver and small intestine at 20 hours after the onset of sepsis. Moreover, plasma lactate levels increased at the late stage of sepsis. CONCLUSION: Because hepatic and intestinal VO2 but not systemic and renal VO2 decreased at 20 hours after CLP, the liver and small intestine seem to be more vulnerable to the hypoxic insult during the hypodynamic stage of polymicrobial sepsis.     

Biomarker and drug-target discovery using proteomics in a new rat model of sepsis-induced acute renal failure

Sepsis is one of the common causes of acute renal failure (ARF). The objective of this study was to identify new biomarkers and therapeutic targets. We present a new rat model of sepsis-induced ARF based on cecal ligation and puncture (CLP). We used this model to find urinary proteins which may be potential biomarkers and/or drug targets. Aged rats were treated with fluids and antibiotics after CLP. Urinary proteins from septic rats without ARF and urinary proteins from septic rats with ARF were compared by difference in-gel electrophoresis (DIGE). CLP surgery elevated interleukin (IL)-6 and IL-10 serum cytokines and blood nitrite compared with sham-operated rats. However, there was a range of serum creatinine values at 24 h (0.4-2.3 mg/dl) and only 24% developed ARF. Histology confirmed renal injury in these rats. Forty-nine percent of rats did not develop ARF. Rats without ARF also had less liver injury. The mortality rate at 24 h was 27% but was increased by housing the post-surgery rats in metabolic cages. Creatinine clearance and urine output 2-8 h after CLP was significantly reduced in rats which died within 24 h. Using DIGE we identified changes in a number of urinary proteins including albumin, brush-border enzymes (e.g., meprin-1-alpha) and serine protease inhibitors. The meprin-1-alpha inhibitor actinonin prevented ARF in aged mice. In summary, we describe a new rat model of sepsis-induced ARF which has a heterogeneous response similar to humans. This model allowed us to use DIGE to find changes in urinary proteins and this approach identified a potential biomarker and drug target - meprin-1-alpha.     

Plasma alpha-glutathione S-transferase: a sensitive indicator of hepatocellular damage during polymicrobial sepsis

HYPOTHESIS: Since studies have found the liver enzyme alpha-glutathione S-transferase (alphaGST) to be a marker of hepatic injury after hemorrhagic shock, alphaGST also may serve as a sensitive indicator of hepatocellular damage during the early stage of polymicrobial sepsis. DESIGN, INTERVENTIONS, AND MAIN OUTCOME MEASURES: Male adult rats were subjected to the cecal ligation and puncture (CLP) model of polymicrobial sepsis or sham operation, followed by fluid resuscitation with isotonic sodium chloride solution. Systemic blood samples were taken at 2, 5, 10, or 20 hours after CLP or sham operation. Plasma levels of alphaGST and lactate were determined using an enzyme immunoassay and enzymatic assay, respectively. Additional animals were examined for morphologic alterations in liver ultrastructure of septic animals using electron microscopy. RESULTS: A similar level of alphaGST (mean +/- SEM, 30.5 +/- 3.5 microg/L) was found in the sham group at all measured time points. Although plasma levels of alphaGST did not change at 2 hours after CLP, they were elevated by 249% at 5 hours after the onset of sepsis and continued to increase throughout the septic course. Plasma lactate levels were significantly increased only at 20 hours after CLP (P<.001). Previous studies have shown that liver transaminase levels did not increase at 5 hours, but at 10 and 20 hours after CLP. In addition, electron microscopy revealed structural changes in hepatocyte morphology at 5 and 20 hours after CLP that were indicative of hepatocellular injury. CONCLUSION: Since plasma alphaGST levels increased earlier than plasma lactate and liver transaminase levels, alphaGST may be a more sensitive indicator of early liver injury and should be used in monitoring hepatocellular damage during the progression of sepsis.     

Complement is activated in kidney by endotoxin but does not cause the ensuing acute renal failure

BACKGROUND: Acute renal failure (ARF) in sepsis occurs when the release of multiple inflammatory mediators is induced by bacterial endotoxins. C3 mRNA is markedly up-regulated in mouse kidney after exposure to lipopolysaccharide (LPS). We hypothesized that LPS could induce tubular synthesis and secretion of C3, leading to activation of the complement cascade and direct renal tubular injury. METHODS: ARF was induced in mice by intravenous injection of LPS and was confirmed by an acute rise in blood urea nitrogen (BUN) and histologically by acute tubular necrosis. Three separate strategies were used to investigate the role of the complement system in this model of ARF: (1) Crry-Ig, a recombinant protein containing the potent murine complement C3 activation inhibitor Crry was injected at the same time as LPS (N = 8). (2) LPS was injected into transgenic mice overexpressing Crry in glomeruli and tubules (N = 8), and (3) LPS was injected into C3-deficient mice (N = 5). RESULTS: Compared with unmanipulated mice, C3 staining by immunofluorescence (IF) microscopy in mice injected with LPS was greater in renal cortical tubular cells (IF score of 2. 1 +/- 0.1 vs. 1.4 +/- 0.2 in controls, P = 0.013), most prominently at the basolateral surface. LPS injection led to a 16- to 42-fold increase in urinary C3 excretion. Despite reduction or complete elimination of renal C3 with maneuvers suppressing complement activation, BUN values were not statistically different across all groups. In no experiment did BUN values correlate with the extent of C3 staining. CONCLUSION: Although LPS up-regulates renal C3 synthesis, resulting in basolateral tubular C3 deposition, this is not responsible for LPS-induced ARF in mice.     

Inducible nitric oxide synthase (iNOS) gene deficiency increases the mortality of sepsis in mice.

BACKGROUND: Nitric oxide (NO) produced by the inducible isoform of NO synthase (iNOS or NOS2) has been implicated in the hypotension, organ failure, and death that complicate sepsis. To avoid the confounding effects and limitations of iNOS inhibitors, we used iNOS gene "knockout" mice to examine the effect of inducible NO production in a model of polymicrobial abdominal sepsis treated with antibiotics. We hypothesized that iNOS gene deficiency would significantly alter outcome. METHODS: C57BL6 wild-type (control) and congenic iNOS knockout mice were studied concurrently. Under halothane anesthesia, the ceca were ligated with 4-0 silk suture and punctured twice with a 26-gauge needle (cecal ligation and puncture, CLP). Survival was followed for 7 days, after which necropsies were performed in surviving animals. In an accompanying study examining the acute effects of sepsis, organ injury at 18 hours after CLP as determined by histology and the degree of cell death by apoptosis were examined with the use of hematoxylin and eosin (H&E) and TUNEL staining and two-channel fluorescence-activated cell sorter (FACS) analysis. RESULTS: Sham laparotomy produced no lethality in either knockout (n = 3) or wild-type (n = 3) animals. Compared with survival in controls (n = 20), survival after CLP in iNOS knockout mice (n = 21) was significantly decreased (P < .01 at 2 days, P = .080 at 7 days, Mantel-Haenszel log-rank test). CLP-induced apoptotic cell death was significantly less in the thymus of iNOS knockout mice compared with wild-type mice. CONCLUSIONS: We conclude that iNOS gene function provides a survival benefit in septic mice and is associated with increased sepsis-induced thymocyte apoptosis. To our knowledge, this is the first survival study examining the effect of iNOS gene deficiency in a clinically relevant model of sepsis.     

丙酮酸乙酯对脓毒症小鼠相关脏器的保护作用

目的:探讨丙酮酸乙酯(EP)对脓毒症小鼠肾脏、肝脏、肺脏组织的保护作用。方法:采用盲肠结扎穿孔术制备小鼠脓毒症模型。100只雄性昆明小鼠随机分为假手术组、脓毒症组、EP预保护组、EP保护组,后三组又设立1h、3h、6h组,每组10只。用分光光度法检测血清碱性磷酸酶(ALP)活性,肝脏、肺脏组织匀浆液中总抗氧化能力(TAOC)和丙二醛(MDA)含量。结果:EP预保护组6h、EP保护组6h血清ALP较损伤组6h显著降低。EP预保护组3h、6h及EP保护组3h、6h肝脏、肺脏组织总抗氧化能力较损伤组相应时间点明显升高。EP干预后,受损肝脏、肺脏组织丙二醛无明显变化。结论:EP可能对脓毒症后。肾脏、肝脏、肺脏等受损脏器起一定的保护作用,其机制与影响氧自由基有关。     

Hepatocellular dysfunction persists during early sepsis despite increased volume of crystalloid resuscitation.

Although hepatocellular dysfunction occurs early in sepsis despite fluid resuscitation, it is unknown if an increased volume of resuscitation protects hepatocellular function. To study this, rats were subjected to sepsis by cecal ligation and puncture (CLP). These and sham-treated rats then received either 3 or 6 mL/100 g BW normal saline subcutaneously. Studies were performed at 5 hours (i.e., early sepsis) or 20 hours (late sepsis) after CLP. Hepatic blood flow was determined by radioactive microspheres, 3H-galactose clearance technique, and laser Doppler flowmetry in both groups. Active hepatocellular function (i.e., Vmax and Km) was assessed by an in vivo indocyanine green clearance technique. The results indicate that: (1) hepatic blood flow increased markedly in early sepsis; (2) Vmax and Km decreased significantly at 5 hours and 20 hours after CLP; and (3) the increased volume of fluid resuscitation did not improve the depressed active hepatocellular function 5 hours following CLP. Cardiac output and hepatic microcirculation, however, were significantly increased in early sepsis. These results confirm the notion that the depression in hepatocellular function in early sepsis is not the result of any reduction of hepatic perfusion. The dissociation of increased hepatic blood flow from depressed hepatocellular function remains despite the larger volume of resuscitation. The hepatocellular dysfunction that occurs even in early sepsis cannot be corrected simply by increasing the volume of crystalloid resuscitation.     

Is circulating endotoxin the trigger for the systemic inflammatory response syndrome seen after injury?

OBJECTIVE: Patients with severe traumatic or burn injury and a mouse model of burn injury were studied early after injury to determine the relation of plasma endotoxin (lipopolysaccharide [LPS]) to the production of proinflammatory cytokines and subsequent resistance to infection. SUMMARY BACKGROUND DATA: Elevated levels of plasma LPS have been reported in patients after serious injury. It has been suggested that circulating LPS may be a trigger for increased proinflammatory cytokine production and may play a role in the septic syndromes seen in a substantial portion of such patients. Yet, despite multiple reports of leakage of LPS from the gut and bacterial translocation after injury in animal models, there is little direct evidence linking circulating LPS with production of inflammatory mediators. METHODS: The authors studied serial samples of peripheral blood from 10 patients with 25% to 50% surface area burns and 8 trauma patients (injury Severity Score, 25-57). Patients were compared with 18 healthy volunteers. The study was focused on the first 10 days after injury before the onset of sepsis or the systemic inflammatory response syndrome. Plasma samples were assayed for LPS, and adherent cells from the blood were studied for basal and LPS-stimulated production of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6). The correlation of increased plasma LPS with TNF-alpha production was studied as was the association of increased plasma LPS and increased TNF-alpha production with subsequent septic complications. We also studied a mouse model of 25% burn injury. Burn mice were compared with sham burn control subjects. Plasma samples were assayed at serial intervals for LPS, and adherent cells from the spleens were studied for basal- and LPS-stimulated production of TNF-alpha, IL-1 beta, and IL-6. Expression of the messenger RNAs for IL-1 beta and TNF-alpha also was measured. The relation of increased TNF-alpha production with mortality from a septic challenge, cecal ligation and puncture (CLP), was determined. Finally, the effect of administration of LPS to normal mice on subsequent mortality after CLP and on TNF-alpha production was studied. RESULTS: Elevated plasma LPS (> 1 pg/mL) was seen in 11 of the 18 patients within 10 days of injury and in no normal control subjects. In this period, patients as compared with control subjects showed increased stimulated production of TNF-alpha, IL-1 beta, and IL-6. Increased TNF-alpha production was not correlated with elevated plasma LPS in the same patients. Neither increased plasma LPS nor increased TNF-alpha production early after injury was correlated with subsequent development of systemic inflammatory response syndrome or sepsis in the patients. Burn mice, as compared with sham burn control subjects, showed elevated plasma LPS levels chiefly in the first 3 days after injury. Increased stimulated production of proinflammatory cytokines by adherent splenocytes from the burn mice also was seen at multiple intervals after injury and did not correlate with mortality from CLP. Increased production of TNF-alpha and IL-1 beta was associated with increased expression of messenger RNAs for these cytokines. Finally, two doses of 1 ng LPS administered 24 hours apart to normal mice had no effect on mortality from CLP performed 7 days later nor on the production of TNF-alpha at the time of CLP. CONCLUSIONS: These findings call into question the idea that circulating LPS is the trigger for increased proinflammatory cytokine production, systemic inflammatory response syndrome, and septic complications in injured patients.     

Estradiol administration improves splanchnic perfusion following trauma-hemorrhage and sepsis.

HYPOTHESIS: The female sex steroid 17beta-estradiol improves immune functions following trauma-hemorrhage in rodent models. Therefore, we hypothesized that 17beta-estradiol administration following trauma-hemorrhage would also improve cardiac output, splanchnic perfusion, and oxygen utilization, even after the induction of subsequent sepsis. SETTING: A university laboratory. INTERVENTION: Male rats underwent midline laparotomy (ie, soft tissue injury). They were bled to a mean arterial pressure of 35 to 40 mm Hg for 90 minutes and resuscitated over 60 minutes with lactated Ringer solution. At the beginning of resuscitation, 17beta-estradiol (l mg/kg) or a vehicle was administered. At 20 hours after resuscitation, polymicrobial sepsis was induced by cecal ligation and puncture (CLP). MAIN OUTCOME MEASURES: At 5 hours after CLP, cardiac performance (via a left ventricular catheter), cardiac output, and organ blood flow were determined using strontium 85 microspheres. Blood samples were collected from the femoral artery and jugular, portal, and renal veins to determine systemic and regional oxygen delivery and consumption. Moreover, circulating levels of 17beta-estradiol, its adrenal precursor dehydroepiandrosterone (DHEA), and corticosterone were assessed by enzyme-linked immunosorbent assay. RESULTS: Hemorrhage and subsequent sepsis significantly depressed cardiac performance, cardiac output, organ perfusion, and oxygen consumption. Estrogen did not restore cardiac output or systemic oxygen consumption; nonetheless, it restored the depressed intestinal perfusion. Rats treated with estrogen had significantly elevated levels of plasma 17beta-estradiol, but the levels of DHEA or corticosterone were not affected. CONCLUSIONS: The increase in gut perfusion could represent a potential mechanism for the salutary effects of 17beta-estradiol following trauma-hemorrhage. Because 17beta-estradiol improves systemic and intestinal perfusion after trauma-hemorrhage and induction of subsequent sepsis, this agent appears to be a promising adjunct for the treatment of trauma victims.     

Acute renal failure in severely burned patients

Acute renal failure (ARF) is a well known complication of severe burns and is an important factor leading to an increase in mortality. In order to analyze possible pathogenetic and prognostic factors associated with ARF in burned patients we reviewed in a retrospective study the files of 328 patients with burns > 10% body surface area (BSA), admitted to our burn unit between 01.01.94 and 01.05.98. We found 48 patients with acute renal failure corresponding with an incidence of 14.6%. Patients with ARF had a mean burned surface area of 48% (13-95) and an abbreviated burn severity index score (ABSI) of 9.8 (4-15). Thirty eight (79%) of these patients had an inhalation injury diagnosed. Renal insufficiency was divided in a late and an early form depending on its time of onset and we found 15 (31%) patients with ARF occurring within the first 5 days of the hospital stay and 33 (69%) patients with ARF developing >5 days following the thermal injury. The incidence of myoglobinuria and hypotension during the resuscitation phase was significantly higher in the group with early ARF, whereas patients with late ARF presented sepsis more frequently than patients with early occurring renal failure. Accordingly, potential nephrotoxic antibiotics were administered more often in patients with late ARF. Patients with ARF were treated by continuous arteriovenous hemofiltration (CAVH) for a mean period of 10.5 days (1-47) and CAVH was associated with a complication rate of 10%. Most of the complications were associated with the vascular access in the femoral artery. The mortality rate in patients with ARF was 85% and death was due to multiple organ failure in 83% of the cases. Only burned BSA and inhalation injury proved to be significantly correlated with the development of ARF, whereas age, third degree burn or electric injury were not significantly different between the two groups. Neither age, TBSA, day of onset of ARF nor duration of the renal replacement therapy proved to be significantly different comparing survivors with non-survivors, and thus predictive for the survival rate.     

Normal mesenteric lymph ameliorates acute kidney injury following lipopolysaccharide challenge in mice

Background: The kidney is one of the prior damaged organs subjected to severe infection and sepsis shock. Our previous studies have shown that the normal mesenteric lymph (NML) obtained from healthy dogs could alleviate multiple organ injuries following endotoxic shock. In the current study, we further investigated the beneficial effect of NML from healthy mice on acute kidney injury (AKI) induced by lipopolysaccharide (LPS) in mice. Methods: The mice in LPS and LPS?+?NML groups received an intraperitoneal injection of LPS (35?mg/kg). One hour later, the treatment of NML was performed and kept for 6?h. Then, the renal function indices, renal morphology, the levels of phosphorylation mitogen-activated protein kinases (MAPKs), markers of sensitization to LPS, as well as pro-inflammatory mediators in renal tissue were observed. Results: Intraperitoneal injection of LPS induced an increased level of urea in plasma, lipopolysaccharide-binding protein (LBP), cluster of differentiation 14 (CD14), tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6), but no obvious changes in the MAPKs in renal tissue. NML treatment decreased the levels of urea, CD14, TNF-α and IL-6 in mice after LPS injection. Conclusion: The current results indicate that NML alleviates LPS-induced AKI through its attenuation of sensitization to LPS.     

Ghrelin down-regulates proinflammatory cytokines in sepsis through activation of the vagus nerve

OBJECTIVE: To test the hypothesis that administration of ghrelin attenuates inflammatory responses in sepsis through vagal nerve stimulation. SUMMARY BACKGROUND DATA: Ghrelin has been demonstrated to possess multiple functions, including stimulation of the vagus nerve. Our recent study has shown that plasma levels of ghrelin were significantly reduced in sepsis; and ghrelin administration improved organ perfusion and function. However, it remained unknown whether ghrelin also decreases proinflammatory cytokines in sepsis and, if so, whether the down-regulatory effect of ghrelin is mediated by activation of the vagus nerve. METHODS: Male rats were subjected to sepsis by cecal ligation and puncture (CLP). At 5 hours after CLP, a bolus intravenous injection of 2 nmol ghrelin was followed by a continuous infusion of 12 nmol ghrelin via a primed 200-microL Alzet mini-pump for 15 hours. At 20 hours after CLP, plasma and peritoneal fluid levels of TNF-alpha and IL-6 were determined. The direct effect of ghrelin on cytokine production was studied using cultured normal rat Kupffer cells or peritoneal macrophages stimulated by lipopolysaccharide (LPS). In additional animals, vagotomy or sham vagotomy was performed in sham and septic animals immediately prior to ghrelin administration and cytokine levels were then measured. RESULTS: Ghrelin significantly reduced TNF-alpha and IL-6 levels in sepsis. In contrast, ghrelin did not inhibit TNF-alpha and IL-6 release from LPS-stimulated Kupffer cells or peritoneal macrophages. However, vagotomy, but not sham vagotomy, prevented ghrelin's down-regulatory effect on TNF-alpha and IL-6 production. CONCLUSIONS: Ghrelin down-regulates proinflammatory cytokines in sepsis through activation of the vagus nerve. Pharmacologic stimulation of the vagus nerve may offer a novel approach of anti-sepsis therapy.     

丙酮酸乙酯调节脓毒症小鼠肝细胞HSP70表达的研究

目的研究丙酮酸乙酯（EP）对脓毒症小鼠肝细胞热休克蛋白70（HSPT0）的调节作用。方法制作小鼠盲肠结扎穿孔模型（CLP），应用丙酮酸乙酯林格氏液（REPS）与乳酸钠林格氏液（RLS）对小鼠进行液体复苏，60只小鼠分3组，各20只：假手术组、CLP模型＋REPS复苏组、CLP模型＋RLS复苏组，检测肝组织丙二醛（MDA）及肝细胞HSP70的表达。结果脓毒症小鼠较假手术组MDA浓度增高，P〈0．01。EP显著提高脓毒症小鼠肝组织的抗氧化能力，REPS组肝组织MDA浓度低于RLS组【（48．18±598）μmol／g．prot vs（78．34±11．16）μmol／gprot，P〈0．01]；REPS组小鼠肝细胞HSPT0表达较RLS组增高[（28．76±5．69）vs（20．04±4．93），P〈0．051。HSP70表达与MDA值呈负相关（r=-0．733，P〈0．01）。结论EP具有的抗氧化作用能提高脓毒症小鼠肝细胞的HSPT0表达。