Early propranolol treatment induces lung heme-oxygenase-1, attenuates metabolic dysfunction,and improves survival following experimental sepsis

Introduction

Pharmacological agents that block beta-adrenergic receptors have been associated with improved outcome in burn injury. It has been hypothesized that injuries leading to a hypermetabolic state, such as septic shock, may also benefit from beta-blockade; however, outcome data in experimental models have been contradictory. Thus, we investigated the effect of beta-blockade with propranolol on survival, hemodynamics, lung heat shock protein (HSP) expression, metabolism and inflammatory markers in a rat cecal ligation and puncture (CLP) model of sepsis.

Methods

Sprague-Dawley rats receiving either repeated doses (30 minutes pre-CLP and every 8 hours for 24 hours postoperatively) of propranolol or control (normal saline), underwent CLP and were monitored for survival. Additionally, lung and blood samples were collected at 6 and 24 hours for analysis. Animals also underwent monitoring to evaluate global hemodynamics.

Results

Seven days following CLP, propranolol improved survival versus control (P < 0.01). Heart rates in the propranolol-treated rats were approximately 23% lower than control rats (P < 0.05) over the first 24 hours, but the mean arterial blood pressure was not different between groups. Metabolic analysis of lung tissue demonstrated an increase in lung ATP/ADP ratio and NAD+ content and a decreased ratio of polyunsaturated fatty acids to monounsaturated fatty acids (PUFA/MUFA). Cytokine analysis of the inflammatory cytokine tumor necrosis factor alpha (TNF-alpha) demonstrated decreased expression of TNF-alpha in both lung and plasma at 24 hours post CLP induced sepsis. Finally, propranolol led to a significant increase in lung hemeoxygenase-1 expression, a key cellular protective heat shock protein (HSP) in the lung. Other lung HSP expression was unchanged.

Conclusions

These results suggest that propranolol treatment may decrease mortality during sepsis potentially via a combination of improving metabolism, suppressing aspects of the inflammatory response and enhancing tissue protection.     

Angiopoietin-1 variant reduces LPS-induced microvascular dysfunction in a murine model of sepsis

Introduction

Severe sepsis is characterised by intravascular or extravascular infection with microbial agents, systemic inflammation and microcirculatory dysfunction, leading to tissue damage, organ failure and death. The growth factor angiopoietin (Ang-1) has therapeutic potential but recombinant Ang-1 tends to aggregate and has a short half-life in vivo. This study aimed to investigate the acute effects of the more stable Ang-1 variant matrilin-1-angiopoietin-1 (MAT.Ang-1) on the function of the microcirculation in an experimental model of sepsis, and whether any protection by MAT-Ang-1 was associated with modulation of inflammatory cytokines, angiogenic factors or the endothelial nitric oxide synthase (eNOS)-Akt and vascular endothelial (VE)-cadherin pathways.

Methods

Aluminium window chambers were implanted into the dorsal skinfold of male C3H/HeN mice (7 to 10 weeks old) to expose the striated muscle microcirculation. Endotoxemia was induced by intraperitoneal injection of lipopolysaccharide (LPS, 1 mg/kg at 0 and 19 hours). MAT.Ang-1 was administered intravenously 20 hours after the onset of sepsis. Microcirculatory function was evaluated by intravital microscopy and Doppler fluximetry.

Results

Endotoxemia resulted in macromolecular leak, which was ameliorated by MAT.Ang-1 post-treatment. LPS induced a dramatic reduction in tissue perfusion, which was improved by MAT.Ang-1. Proteome profiler array analysis of skeletal muscle also demonstrated increased inflammatory and reduced angiogenic factors during endotoxemia. MAT.Ang-1 post-treatment reduced the level of IL-1β but did not significantly induce the expression of angiogenic factors. MAT.Ang-1 alone did not induce leak or increase angiogenic factors but did reduce vascular endothelial growth factor expression in controls.

Conclusion

Administration of MAT.Ang-1 after the onset of sepsis protects the microcirculation from endotoxemia-induced vascular dysfunction through reducing inflammation but without pro-angiogenic actions, thus representing a novel, potential pharmacotherapeutic agent for the treatment of sepsis.     

Endothelial dysfunction is a potential contributor to multiple organ failure and mortality in aged mice subjected to septic shock: preclinical studies in a murine model of cecal ligation and puncture

Introduction

The goal of the current study was to investigate the effect of aging on the development of endothelial dysfunction in a murine model of sepsis, and to compare it with the effect of genetic deficiency of the endothelial isoform of nitric oxide synthase (eNOS).

Methods

Cecal ligation and puncture (CLP) was used to induce sepsis in mice. Survival rates were monitored and plasma indices of organ function were measured. Ex vivo studies included the measurement of vascular function in thoracic aortic rings, assessment of oxidative stress/cellular injury in various organs and the measurement of mitochondrial function in isolated liver mitochondria.

Results

eNOS deficiency and aging both exacerbated the mortality of sepsis. Both eNOS-deficient and aged mice exhibited a higher degree of sepsis-associated multiple organ dysfunction syndrome (MODS), infiltration of tissues with mononuclear cells and oxidative stress. A high degree of sepsis-induced vascular oxidative damage and endothelial dysfunction (evidenced by functional assays and multiple plasma markers of endothelial dysfunction) was detected in aortae isolated from both eNOS^−/− and aged mice. There was a significant worsening of sepsis-induced mitochondrial dysfunction, both in eNOS-deficient mice and in aged mice. Comparison of the surviving and non-surviving groups of animals indicated that the severity of endothelial dysfunction may be a predictor of mortality of mice subjected to CLP-induced sepsis.

Conclusions

Based on the studies in eNOS mice, we conclude that the lack of endothelial nitric oxide production, on its own, may be sufficient to markedly exacerbate the severity of septic shock. Aging markedly worsens the degree of endothelial dysfunction in sepsis, yielding a significant worsening of the overall outcome. Thus, endothelial dysfunction may constitute an early predictor and independent contributor to sepsis-associated MODS and mortality in aged mice.     

Depletion of neutrophil extracellular traps in vivo results in hypersusceptibility to polymicrobial sepsis in mice

Introduction

Although the formation of neutrophil (PMN) extracellular traps (NETs) has been detected during infection and sepsis, their role in vivo is still unclear. This study was performed in order to evaluate the influence of NETs depletion by administration of recombinant human (rh)DNase on bacterial spreading, PMN tissue infiltration and inflammatory response in a mouse model of polymicrobial sepsis.

Methods

In a prospective controlled double-armed animal trial, polymicrobial sepsis was induced by cecal ligation and puncture (CLP). After CLP, mice were treated with rhDNase or phosphate buffered saline, respectively. Survival, colony forming unit (CFU) counts in the peritoneal cavity, lung, liver and blood were determined. PMN and platelet counts, IL-6 and circulating free (cf)-DNA/NETs levels were monitored. PMN infiltration, as well as organ damage, was analyzed histologically in the lungs and liver. Capability and capacity of PMN to form NETs were determined over time.

Results

cf-DNA/NETs were found to be significantly increased 6, 24, and 48 hours after CLP when compared to the levels determined in sham and naïve mice. Peak levels after 24 hours were correlated to enhanced capacity of bone marrow-derived PMN to form NETs after ex vivo stimulation with phorbol-12-myristate-13-acetate at the same time. rhDNase treatment of mice resulted in a significant reduction of cf-DNA/NETs levels 24 hours after CLP (P < 0.001). Although overall survival was not affected by rhDNase treatment, median survival after 24 hours was significantly lower when compared with the CLP group (P < 0.01). In mice receiving rhDNase treatment, CFU counts in the lung (P < 0.001) and peritoneal cavity (P < 0.05), as well as serum IL-6 levels (P < 0.001), were found to be already increased six hours after CLP. Additionally, enhanced PMN infiltration and tissue damage in the lungs and liver were found after 24 hours. In contrast, CFU counts in mice without rhDNase treatment increased later but more strongly 24 hours after CLP (P < 0.001). Similarly, serum IL-6 levels peaked after 24 hours (P < 0.01).

Conclusions

This study shows, for the first time, that depletion of NETs by rhDNase administration impedes the early immune response and aggravates the pathology that follows polymicrobial sepsis in vivo.     

Kinetics and protective role of autophagy in a mouse cecal ligation and puncture-induced sepsis

Introduction

It is not well understood whether the process of autophagy is accelerated or blocked in sepsis, and whether it is beneficial or harmful to the immune defense mechanism over a time course during sepsis. Our aim was to determine both the kinetics and the role of autophagy in sepsis.

Methods

We examined autophagosome and autolysosome formation in a cecal ligation and puncture (CLP) mouse model of sepsis (in C57BL/6N mice and GFP-LC3 transgenic mice), using western blotting, immunofluorescence, and electron microscopy. We also investigated the effect of chloroquine inhibition of autophagy on these processes.

Results

Autophagy, as demonstrated by increased LC3-II/LC3-I ratios, is induced in the liver, heart, and spleen over 24 h after CLP. In the liver, autophagosome formation peaks at 6 h and declines by 24 h. Immunofluorescent localization of GFP-LC3 dots (alone and with lysosome-associated membrane protein type 1 (LAMP1)), as well as electron microscopic examination, demonstrate that both autophagosomes and autolysosomes are increased after CLP, suggesting that intact autophagy mechanisms operate in the liver in this model. Furthermore, inhibition of autophagy process by chloroquine administration immediately after CLP resulted in elevated serum transaminase levels and a significant increase in mortality.

Conclusions

All autophagy-related processes are properly activated in the liver in a mouse model of sepsis; autophagy appears to play a protective role in septic animals.     

Simvastatin inhibits apoptosis of endothelial cells induced by sepsis through upregulating the expression of Bcl-2 and downregulating Bax

BACKGROUND:

Many studies have showed that apoptosis of endothelial cells plays a curial role in the progress of sepsis. But the role of simvastatin in apoptosis of endothelial cells induced by sepsis is not clear. The present study aimed to investigate the role of simvastatin in apoptosis of endothelial cells induced by sepsis and its mechanism.

METHODS:

Human umbilical vein endothelial cells (HUVECs) were randomly divided into three groups: control group, sepsis serum intervention group (sepsis group) and simvastatin+sepsis serum intervention group (simvastatin group). After 24-hour incubation with corresponding culture medium, the relative growth rate of HUVECS in different groups was detected by MTT assay; the apoptosis of HUVECs was detected by Hoechst33258 assay and flow cytometry; and the expression of the Bcl-2 and Bax genes of HUVECs was detected by PCR.

RESULTS:

Compared with the sepsis group, HUVECs in the simvastatin group had a higher relative growth rate. Apoptotic HUVECs decreased significantly in the simvastatin group in comparison with the sepsis group. Expression of the Bcl-2 gene in HUVECs decreased obviously, but the expression of the Bax gene increased obviously after 24-hour incubation with sepsis serum; however, the expression of the Bcl-2 and Bax genes was just the opposite in the simvastatin group.

CONCLUSIONS:

Our study suggests that simvastatin can inhibit apoptosis of endothelial cells induced by sepsis through upregulating the expression of Bcl-2 and downregulating Bax. It may be one of the mechanisms for simvastatin to treat sepsis.KEY WORDS: Simvastatin, Sepsis, Endothelial cells, Apoptosis, Bcl-2 gene, Bax gene     

The anti-inflammatory effect of the synthetic antimicrobial peptide 19-2.5 in a murine sepsis model: a prospective randomized study

Introduction

Increasing rates of multi-resistant bacteria are a major problem in the treatment of critically ill patients. Furthermore, conventional antibiotics lead to the release of bacterial derived membrane parts initiating pro-inflammatory cascades with potential harm to the patient. Antimicrobial peptides (AMP) may kill bacteria without releasing pro-inflammatory factors. Thus, we compared three newly developed synthetic anti-lipopolysaccharide peptides (SALPs) with a broader range of efficacy to suppress cytokine release in plasma and CD14 mRNA expression in organ tissue in a murine, polymicrobial sepsis model.

Methods

A randomized, experimental trial was conducted in an animal research facility. Male NMRI mice (n = 90; 8- to 12-weeks old) were randomized to the following six groups: (i) sham operation and parenteral vehicle (NaCl 0.9%) administration (sham); (ii) cecal ligation and puncture (CLP) and vehicle infusion (sepsis-control), (iii) CLP and polymyxin B infusion (polyB), or (iv to vi) CLP and infusion of three different synthetic antimicrobial peptides Peptide 19-2.5 (Pep2.5), Peptide 19-4 (Pep4) or Peptide 19-8 (Pep8). All animals underwent arterial and venous catheterization for hemodynamic monitoring 48 hours prior to CLP or sham-operation. Physical appearance and behavior (activity), plasma cytokine levels, and CD14 mRNA expression in heart, lung, liver, spleen and kidney tissue were determined 24 hours after CLP or sham operation.

Results

Only Pep2.5 significantly enhanced the activity after CLP, whereas none of the therapeutic regimens elevated the mean arterial pressure or heart rate. The strongly elevated IL-6, IL-10 and monocyte chemoattractant protein serum levels in septic animals were significantly reduced after Pep2.5 administration (P < 0.001, P < 0.001, and P < 0.001, respectively). Similarly, Pep2.5 significantly reduced the sepsis-induced CD14 mRNA expression in heart (P = 0.003), lung (P = 0.008), and spleen tissue (P = 0.009) but not in kidney and liver.

Conclusions

Structurally variable SALPs exhibit major differences in their anti-inflammatory effect in vivo. Continuous parenteral administration of Pep2.5 is able to reduce sepsis-induced cytokine release and tissue inflammation.     

Pulmonary vascular permeability changes in an ovine model of methicillin-resistant Staphylococcus aureus sepsis

Introduction

Endothelial dysfunction is a hallmark of sepsis, associated with lung transvascular fluid flux and pulmonary dysfunction in septic patients. We tested the hypothesis that methicillin-resistant Staphylococcus aureus (MRSA) sepsis following smoke inhalation increases pulmonary transvascular fluid flux via excessive nitric oxide (NO) production.

Methods

Ewes were chronically instrumented, and randomised into either a control or MRSA sepsis (MRSA and smoke inhalation) group.

Results

Pulmonary function remained stable in the control group, whereas the MRSA sepsis group developed impaired gas exchange and significantly increased lung lymph flow, permeability index and bloodless wet-to-dry weight-ratio (W/D ratio). The plasma nitrate/nitrite (NOx) levels, lung inducible nitric oxide synthases (iNOS) and endothelial nitric oxide synthases (eNOS), vascular endothelial growth factor (VEGF) protein expressions and poly-(ADP)-ribose (PAR) were significantly increased by MRSA challenge.

Conclusions

These results provide evidence that excessive NO production may mediate pulmonary vascular hyperpermeability in MRSA sepsis via up regulation of reactive radicals and VEGF.     

Levosimendan attenuates multiple organ injury and improves survival in peritonitis-induced septic shock: studies in a rat model

Introduction

The aim of this study was to investigate the effects of levosimendan on rodent septic shock induced by cecal ligation and puncture (CLP).

Methods

Three hours after peritonitis-induced sepsis, male Wistar rats were randomly assigned to receive an intravenous infusion of levosimendan (1.2 μg/kg/min for 10 min and then 0.3 μg/kg/min for 6 h) or an equivalent volume of saline and vehicle (5% dextrose) solution.

Results

The levosimendan-treated CLP animals had significantly higher arterial pressure and lower biochemical indices of liver and kidney dysfunction compared to the CLP animals (P < 0.05). Plasma interleukin-1β, nitric oxide and organ superoxide levels in the levosimendan-treated CLP group were less than those in CLP rats treated with vehicle (P < 0.05). In addition, the inducible nitric oxide synthase (iNOS) in lung and caspase-3 expressions in spleen were significantly lower in the levosimendan-treated CLP group (P < 0.05). The administration of CLP rats with levosimendan was associated with significantly higher survival (61.9% vs. 40% at 18 h after CLP, P < 0.05). At postmortem examination, the histological changes and neutrophil filtration index in liver and lung were significantly attenuated in the levosimendan-treated CLP group (vs. CLP group, P < 0.05).

Conclusions

In this clinically relevant model of septic shock induced by fecal peritonitis, the administration of levosimendan had beneficial effects on haemodynamic variables, liver and kidney dysfunction, and metabolic acidosis. (1) Lower levels of interleukin-1β, nitric oxide and superoxide, (2) attenuation of iNOS and caspase-3 expressions, and (3) decreases of neutrophil infiltration by levosimendan in peritonitis-induced sepsis animals suggest that anti-inflammation and anti-apoptosis effects of levosimendan contribute to prolonged survival.     

Effects of intra-abdominal sepsis on atherosclerosis in mice

Introduction

Sepsis and other infections are associated with late cardiovascular events. Although persistent inflammation is implicated, a causal relationship has not been established. We tested whether sepsis causes vascular inflammation and accelerates atherosclerosis.

Methods

We performed prospective, randomized animal studies at a university research laboratory involving adult male ApoE-deficient (ApoE^−/−) and young C57B/L6 wild-type (WT) mice. In the primary study conducted to determine whether sepsis accelerates atherosclerosis, we fed ApoE^−/− mice (N = 46) an atherogenic diet for 4 months and then performed cecal ligation and puncture (CLP), followed by antibiotic therapy and fluid resuscitation or a sham operation. We followed mice for up to an additional 5 months and assessed atheroma in the descending aorta and root of the aorta. We also exposed 32 young WT mice to CLP or sham operation and followed them for 5 days to determine the effects of sepsis on vascular inflammation.

Results

ApoE^−/− mice that underwent CLP had reduced activity during the first 14 days (38% reduction compared to sham; P < 0.001) and sustained weight loss compared to the sham-operated mice (−6% versus +9% change in weight after CLP or sham surgery to 5 months; P < 0.001). Despite their weight loss, CLP mice had increased atheroma (46% by 3 months and 41% increase in aortic surface area by 5 months; P = 0.03 and P = 0.004, respectively) with increased macrophage infiltration into atheroma as assessed by immunofluorescence microscopy (0.52 relative fluorescence units (rfu) versus 0.97 rfu; P = 0.04). At 5 months, peritoneal cultures were negative; however, CLP mice had elevated serum levels of interleukin 6 (IL-6) and IL-10 (each at P < 0.05). WT mice that underwent CLP had increased expression of intercellular adhesion molecule 1 in the aortic lumen versus sham at 24 hours (P = 0.01) that persisted at 120 hours (P = 0.006). Inflammatory and adhesion genes (tumor necrosis factor α, chemokine (C-C motif) ligand 2 and vascular cell adhesion molecule 1) and the adhesion assay, a functional measure of endothelial activation, were elevated at 72 hours and 120 hours in mice that underwent CLP versus sham-operations (all at P <0.05).

Conclusions

Using a combination of existing murine models for atherosclerosis and sepsis, we found that CLP, a model of intra-abdominal sepsis, accelerates atheroma development. Accelerated atheroma burden was associated with prolonged systemic, endothelial and intimal inflammation and was not explained by ongoing infection. These findings support observations in humans and demonstrate the feasibility of a long-term follow-up murine model of sepsis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0469-1) contains supplementary material, which is available to authorized users.     

The angiotensin II AT1 receptor-associated protein Arap1 is involved in sepsis-induced hypotension

Introduction

Hypotension in septic patients results from hypovolemia, vasodilatation and hyporeactivity to vasoconstrictors, such as angiotensin II. The AT1 receptor-associated protein 1 (Arap1) is expressed in vascular smooth muscle cells and increases the surface expression of the AT1-receptor in vitro. We hypothesized that dysregulation of Arap1 may contribute to vascular hyporeactivity to angiotensin II during endotoxemia.

Methods

Arap1-deficient mice were used to assess the role of Arap1 in sepsis-induced hypotension. The isolated perfused kidney was used as an in vitro model to determine the relevance of Arap1 for vascular resistance and sensitivity to angiotensin II.

Results

During endotoxemia, mean arterial blood pressure (MAP) decreased in both genotypes, with the time course of sepsis-induced hypotension being markedly accelerated in Arap1-/- compared to +/+ mice. However, baseline MAP was similar in Arap1-/- and wildtype mice (102 ± 2 vs.103 ± 2 mmHg; telemetry measurements; n = 10; P = 0.66). Following lipopolysaccharide (LPS) injections (3 mg/kg), Arap1 expression was successively down-regulated in the wildtype mice, reaching levels below 10% of baseline expression. The endotoxemia-related decline in Arap1 expression could be recapitulated in cultured mesangial cells by incubation with pro-inflammatory cytokines, such as tumor necrosis factor α and interferon γ. Plasma renin concentration was increased in Arap1-/- mice compared to wildtype mice (66 ± 6 vs. 41 ± 4 ng AngI/ml/h; n = 23; P = 0.001), presumably contributing to preserved MAP under baseline conditions. The sensitivity of the vasculature to angiotensin II was reduced in Arap1-/- compared to +/+ mice, as determined in the isolated perfused kidney.

Conclusions

Our data suggest that down-regulation of Arap1 expression during sepsis contributes to the development of hypotension by causing reduced vascular sensitivity to angiotensin II.     

Multiple gene-to-gene interactions in children with sepsis: a combination of five gene variants predicts outcome of life-threatening sepsis

Introduction

The aim of the study was to identify the dependency structure of genetic variants that can influence the outcome for paediatric patients with sepsis.

Methods

We evaluated the role of single nucleotide polymorphisms for five genes: bactericidal permeability increasing protein (BPI; rs5743507), lipopolysaccharide-binding protein (LBP; rs2232618), toll-like receptor 4 (TLR4; rs4986790), heat shock protein 70 (HSP 70; rs2227956), and interleukin 6 (IL-6; rs1800795) in 598 children aged 0 to 19 years that were admitted to a paediatric intensive care unit with fever, systemic inflammatory response syndrome, sepsis, severe sepsis, septic shock, or multiple organ dysfunction syndrome. A control group of 529 healthy individuals was included. Multi-way contingency tables were constructed and statistically evaluated using log-linear models. Typical gene combinations were found for both study groups.

Results

Detailed analyses of the five studied gene profiles revealed significant differences in sepsis survival. Stratification into high-risk, intermediate-risk, and low-risk groups of paediatric patients can predict the severity of sepsis.

Conclusions

Analysis of single nucleotide polymorphisms for five genes can be used as a predictor of sepsis outcome in children.     

Induced expression and functional effects of aquaporin-1 in human leukocytes in sepsis

Introduction

Gene expression profiling was performed via DNA microarrays in leukocytes from critically ill trauma patients nonseptic upon admission to the ICU, who subsequently developed either sepsis (n = 2) or severe sepsis and acute respiratory distress syndrome (n = 3). By comparing our results with published expression profiling studies in animal models of sepsis and lung injury, we found aquaporin-1 to be differentially expressed across all studies. Our aim was to determine how the water channel aquaporin-1 is involved in regulating the immune response in critically ill patients during infection acquired in the ICU.

Methods

Following the results of the initial genetic screening study, we prospectively followed aquaporin-1 leukocyte expression patterns in patients with ICU-acquired sepsis who subsequently developed septic shock (n = 16) versus critically ill patients who were discharged without developing sepsis (n = 13). We additionally determined aquaporin-1 expression upon lipopolysaccharide (LPS) exposure and explored functional effects of aquaporin-1 induction in polymorphonuclear granulocytes (PMNs).

Results

Leukocyte aquaporin-1 expression was induced at the onset of sepsis (median 1.71-fold increase; interquartile range: 0.99 to 2.42, P = 0.012 from baseline) and was further increased upon septic shock (median 3.00-fold increase; interquartile range: 1.20 to 5.40, P = 0.023 from sepsis, Wilcoxon signed-rank test); no difference was observed between baseline and discharge in patients who did not develop sepsis. Stimulation of PMNs by LPS led to increased expression of aquaporin-1 in vitro, which could be abrogated by the NF-κB inhibitor EF-24. PMN hypotonic challenge resulted in a transient increase of the relative cell volume, which returned to baseline after 600 seconds, while incubation in the presence of LPS resulted in persistently increased cell volume. The latter could be abolished by blocking aquaporin-1 with mercury and restored by incubation in β-mercaptoethanol, which abrogated the action of mercury inhibition.

Conclusions

Aquaporin-1 is induced in leukocytes of patients with ICU-acquired sepsis and exhibits higher expression in septic shock. This phenomenon may be due to LPS-triggered NF-κB activation that can also lead to alterations in plasma membrane permeability.     

Renal effects of treatment with a TLR4 inhibitor in conscious septic sheep

Introduction

Acute kidney injury (AKI) is a common and feared complication of sepsis. The pathogenesis of sepsis-induced AKI is largely unknown, and therapeutic interventions are mainly supportive. In the present study, we tested the hypothesis that pharmacological inhibition of Toll-like receptor 4 (TLR4) would improve renal function and reduce renal damage in experimental sepsis, even after AKI had already developed.

Methods

Sheep were surgically instrumented and subjected to a 36-hour intravenous infusion of live Escherichia coli. After 12 hours, they were randomized to treatment with a selective TLR4 inhibitor (TAK-242) or vehicle.

Results

The E. coli caused normotensive sepsis characterized by fever, increased cardiac index, hyperlactemia, oliguria, and decreased creatinine clearance. TAK-242 significantly improved creatinine clearance and urine output. The increase in N-acetyl-beta-D-glucosaminidas, a marker of tubular damage, was attenuated. Furthermore, TAK-242 reduced the renal neutrophil accumulation and glomerular endothelial swelling caused by sepsis. These effects were independent of changes in renal artery blood flow and renal microvascular perfusion in both cortex and medulla. TAK-242 had no effect per se on the measured parameters.

Conclusions

These results show that treatment with a TLR4 inhibitor is able to reverse a manifest impairment in renal function caused by sepsis. In addition, the results provide evidence that the mechanism underlying the effect of TAK-242 on renal function does not involve improved macro-circulation or micro-circulation, enhanced renal oxygen delivery, or attenuation of tubular necrosis. TLR4-mediated inflammation resulting in glomerular endothelial swelling may be an important part of the pathogenesis underlying Gram-negative septic acute kidney injury.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0488-y) contains supplementary material, which is available to authorized users.     

Procalcitonin-guided antibiotics in severe sepsis

Citation

Nobre V, Harbarth S, Graf JD, Rohner P, Pugin J: Use of procalcitonin to shorten antibiotic treatment duration in septic patients: a randomized trial. Am J Respir Crit Care Med 2008, 177: 498–505 [1].

Background

The duration of antibiotic therapy in critically ill patients with sepsis can result in antibiotic overuse, increasing the risk of developing bacterial resistance. Procalcitonin (PCT)-guided antibiotic use reduces antibiotic exposure in community-acquired pneumonia. Whether it might also reduce antibiotic exposure in severe sepsis is unknown.

Methods

Objective

To test the hypothesis that an algorithm based on serial measurements of PCT allows reduction in the duration of antibiotic therapy compared with empirical rules, and does not result in more adverse outcomes in patients with severe sepsis and septic shock.

Design

Single-center, non-blinded randomized controlled trial.

Setting

Mixed medical and surgical ICU at a university teaching hospital.

Subjects

79 adult patients with suspected severe sepsis or septic shock.

Intervention

All patients had circulating PCT levels drawn daily. In patients randomly assigned to the intervention group, antibiotics were stopped when PCT levels had decreased 90% or more from the initial value (if clinicians agreed) but not before Day 3 (if baseline PCT levels were <1 mg/L) or Day 5 (if baseline PCT levels were >1 mg/L). In control patients, clinicians decided on the duration of antibiotic therapy based on empirical rules.

Outcome

Systemic antibiotic exposure, measured using three variables: 1) duration of antibiotic treatment, 2) antibiotic exposure days per 1000 inpatient days, and 3) days alive without antibiotics within the 28-day follow-up period.

Results

Patients assigned to the PCT group had 3.5-day shorter median duration of antibiotic therapy for the first episode of infection than control subjects (intention-to-treat, n = 79, P = 0.15). In patients in whom a decision could be taken based on serial PCT measurements, PCT guidance resulted in a 4-day reduction in the duration of antibiotic therapy (per protocol, n = 68, P = 0.003) and a smaller overall antibiotic exposure (P = 0.0002). A similar mortality and recurrence of the primary infection were observed in PCT and control groups. A 2-day shorter intensive care unit stay was also observed in patients assigned to the PCT group (P = 0.03).

Conclusion

Our results suggest that a protocol based on serial PCT measurement allows reducing antibiotic treatment duration and exposure in patients with severe sepsis and septic shock without apparent harm.     

Therapeutic efficacy of CXCR3 blockade in an experimental model of severe sepsis

Introduction

In our previous studies we demonstrated that CXC chemokine receptor 3 (CXCR3) participates in the regulation of lymphocyte trafficking during cecal ligation and puncture (CLP)-induced sepsis. In this study, we evaluated the effects of treatment with anti-CXCR3 immunoglobulin (IgG) and antibiotics on outcome during septic shock caused by CLP.

Methods

C57BL/6J mice were treated with neutralizing IgG against CXCR3 plus Primaxin either 24 hours prior to, 2 hours after or 6 hours after CLP. Control mice received nonspecific IgG plus Primaxin in the same regimen. Survival, core body temperature, bacterial clearance and systemic cytokine production were evaluated.

Results

Our results show that treatment with anti-CXCR3 IgG plus Primaxin significantly improved survival when administered 24 hours prior to CLP (50% vs. 10%), 2 hours after CLP (55% vs. 10%) or 6 hours after CLP (55% vs. 25%) compared with mice receiving nonspecific IgG plus Primaxin. Treatment with anti-CXCR3 plus Primaxin 24 hours prior to CLP attenuated hypothermia and IL-6 and macrophage inflammatory protein 2 (MIP-2) production but did not alter bacterial clearance. Treatment with anti-CXCR3 IgG and Primaxin 2 hours after CLP did not improve bacterial clearance and systemic cytokine production compared with mice treated with IgG and Primaxin, whereas 6 hours after CLP the bacterial clearance and IL-6 and MIP-2 concentrations, both in plasma and peritoneal lavage fluid, were significantly improved in mice receiving anti-CXCR3 IgG and Primaxin compared with mice that only received nonspecific IgG and Primaxin.

Conclusion

The results from this study indicate that neutralization of CXCR3 prior to, 2 hours after or 6 hours after the initiation of CLP-induced septic shock improves survival and attenuates CLP-induced inflammation and physiologic dysfunction.     

Hydroxyethyl starch in severe sepsis: end of starch era?

Expanded abstract

Citation

Perner A, Haase N, Guttormsen AB, Tenhunen J, Klemenzson G, Åneman A, Madsen KR, Møller MH, Elkjær JM, Poulsen LM, Bendtsen A, Winding R, Steensen M, Berezowicz P, Søe-Jensen P, Bestle M, Strand K, Wiis J, White JO, Thornberg KJ, Quist L, Nielsen J, Andersen LH, Holst LB, Thormar K, Kjældgaard AL, Fabritius ML, Mondrup F, Pott FC, Møller TP, Winkel P, Wetterslev J; 6S Trial Group; Scandinavian Critical Care Trials Group: Hydroxyethyl starch 130/0.42 versus Ringer''s acetate in severe sepsis. N Engl J Med 2012, 367:124-34.

Background

Hydroxyethyl starch (HES) is widely used for fluid resuscitation in ICUs, but its safety and efficacy have not been established in patients with severe sepsis.

Methods

Objective

To assess the effects of HES 130/0.4 compared with a balanced crystalloid solution on mortality and end-stage kidney failure in patients with severe sepsis.

Design

Multicenter, parallel-group, blinded, randomized clinical trial, in patients with severe sepsis.

Interventions

Patients with severe sepsis admitted to the ICU received fluid resuscitation with either 6% HES 130/0.42 (Tetraspan) or Ringer''s acetate at a dose of up to 33 ml per kilogram of ideal body weight per day.

Results

Of the 804 patients who underwent randomization, 798 were included in the modified intention-to-treat population. The two intervention groups had similar baseline characteristics. At 90 days after randomization, 201 of 398 patients (51%) assigned to HES 130/0.42 had died, as compared with 172 of 400 patients (43%) assigned to Ringer''s acetate (relative risk, 1.17; 95% confidence interval (CI), 1.01 to 1.36; P = 0.03); 1 patient in each group had end-stage kidney failure. In the 90-day period, 87 patients (22%) assigned to HES 130/0.42 were treated with renal replacement therapy versus 65 patients (16%) assigned to Ringer''s acetate (relative risk, 1.35; 95% CI, 1.01 to 1.80; P = 0.04), and 38 patients (10%) and 25 patients (6%), respectively, had severe bleeding (relative risk, 1.52; 95% CI, 0.94 to 2.48; P = 0.09). The results were supported by multivariate analyses, with adjustment for known risk factors for death or acute kidney injury at baseline.

Conclusions

Patients with severe sepsis assigned to fluid resuscitation with HES 130/0.42 had an increased risk of death at day 90 and were more likely to require renal replacement therapy compared with those receiving Ringer''s acetate.     

Silencing airway epithelial cell-derived hepcidin exacerbates sepsis-induced acute lung injury

Introduction

The production of antimicrobial peptides by airway epithelial cells is an important component of the innate immune response to pulmonary infection and inflammation. Hepcidin is a β-defensin-like antimicrobial peptide and acts as a principal iron regulatory hormone. Hepcidin is mostly produced by hepatocytes, but is also expressed by other cells, such as airway epithelial cells. However, nothing is known about its function in lung infections and inflammatory diseases. We therefore sought to investigate the role of airway epithelial cell-derived hepcidin in sepsis-induced acute lung injury.

Methods

Acute lung injury was induced by polymicrobial sepsis via cecal ligation and puncture (CLP) surgery. Adenovirus-mediated short hairpin RNA specific for the mouse hepcidin gene hepc1 and control adenovirus were intratracheally injected into mice. The adenovirus-mediated knockdown of hepcidin in airway epithelial cells was evaluated in vivo. Lung injury and the seven-day survival rate were assessed. The levels of hepcidin-related iron export protein ferroportin were measured, and the iron content and function of alveolar macrophages were evaluated.

Results

The hepcidin level in airway epithelial cells was upregulated during polymicrobial sepsis. The knockdown of airway epithelial cell-derived hepcidin aggravated the polymicrobial sepsis-induced lung injury and pulmonary bacterial infection and increased mortality (53.33% in Ad-shHepc1-treated mice versus 12.5% in Ad-shNeg-treated mice, P <0.05). The knockdown of hepcidin in airway epithelial cells also led to reduced ferroportin degradation and a low intracellular iron content in alveolar macrophages. Moreover, alveolar macrophages form the airway epithelial cell-derived hepcidin knockdown mice showed impaired phagocytic ability than those from the control mice.

Conclusions

Airway epithelial cell-derived hepcidin plays an important role in CLP-induced acute lung injury. The severe lung injury in the airway epithelial cell-derived hepcidin knockdown mice is at least partially related to the altered intracellular iron level and function of alveolar macrophages.     

Inhibition of complement C5a prevents breakdown of the blood-brain barrier and pituitary dysfunction in experimental sepsis

Introduction

Septic encephalopathy secondary to a breakdown of the blood-brain barrier (BBB) is a known complication of sepsis. However, its pathophysiology remains unclear. The present study investigated the effect of complement C5a blockade in preventing BBB damage and pituitary dysfunction during experimental sepsis.

Methods

Using the standardised caecal ligation and puncture (CLP) model, Sprague-Dawley rats were treated with either neutralising anti-C5a antibody or pre-immune immunoglobulin (Ig) G as a placebo. Sham-operated animals served as internal controls.

Results

Placebo-treated septic rats showed severe BBB dysfunction within 24 hours, accompanied by a significant upregulation of pituitary C5a receptor and pro-inflammatory cytokine expression, although gene levels of growth hormone were significantly attenuated. The pathophysiological changes in placebo-treated septic rats were restored by administration of neutralising anti-C5a antibody to the normal levels of BBB and pituitary function seen in the sham-operated group.

Conclusions

Collectively, the neutralisation of C5a greatly ameliorated pathophysiological changes associated with septic encephalopathy, implying a further rationale for the concept of pharmacological C5a inhibition in sepsis.     

Whole blood impedance aggregometry as a biomarker for the diagnosis and prognosis of severe sepsis

Introduction

Sepsis leads to an activation of the immune system and hemostatis. However, studies on platelet aggregation in severe sepsis using impedance aggregometry have not been performed and the diagnostic and prognostic capabilities are unknown. In the present study we hypothesized that impedance aggregometry findings might serve as a biomarker for the diagnosis and prognosis of severe sepsis.

Methods

Eighty patients with severe sepsis and 50 postoperative patients were included in the prospective observational study. Platelet function was determined at the first day of severe sepsis and surgery, respectively, using impedance aggregometry (Multiplate^®). Moreover, platelet count, procalcitonin, interleukin 6, C-reactive protein and 30-day mortality were determined.

Results

Compared to postoperative patients, platelet aggregation was significantly reduced in patients with severe sepsis (collagen-test: 70.8 (44.4, 83.2) arbitrary units (A.U.) vs. 26.8 (12.7, 45.8) A.U.; P <0.001; median and quartiles). Furthermore, marked differences in platelet function were observed in survivors and non-survivors of severe sepsis (collagen-test: 33.4 (10.9, 48.8) A.U. vs. 12.4 (6.5, 25.0) A.U.; P = 0.001). Kaplan-Meier analysis demonstrated that higher platelet function was associated with a mortality of 10%, while mortality was 40% when platelet function was low (collagen-test; P = 0.002). The odds ratio was 6.0. In both univariate and multivariate analyses (including procalcitonin, IL6, C-reactive protein and platelet count) impedance aggregometry using collagen as the activator proved to be the best and an independent predictor for the diagnosis and prognosis of severe sepsis in critical illness.

Conclusions

In severe sepsis, impedance aggregometry allows better prediction of diagnosis and survival than conventional biomarkers and platelet count.