Continuous administration of enteral lipid- and protein-rich nutrition limits inflammation in a human endotoxemia model.

OBJECTIVE: An overzealous inflammatory response is an important cause of morbidity and mortality in surgical, trauma, and critically ill patients. Enteral administration of lipid-rich nutrition was previously shown to attenuate inflammation and reduce organ damage via a cholecystokinin-1 receptor-mediated vagovagal reflex in animal studies. The current preclinical study investigates the immunomodulatory potential of a custom-made enteral nutrition during systemic inflammation in man. DESIGN: Double-blind, randomized controlled trial. SETTING: Intensive care research unit. SUBJECTS: Male volunteers. INTERVENTIONS: After an overnight fast, 18 healthy male subjects received an IV bolus of Escherichia coli lipopolysaccharide (2 ng/kg). Subjects in the fasted group (n = 6) were deprived of food throughout the study, while subjects in the intervention groups were fed either custom-made lipid- and protein-rich nutrition (n = 6) or isocaloric control nutrition (n = 6) via nasojejunal tube, starting 1 hour prior to lipopolysaccharide administration until 6 hours afterward. MEASUREMENTS AND MAIN RESULTS: Bolus lipopolysaccharide administration resulted in a marked inflammatory response. Continuous postpyloric administration of nutrition significantly increased plasma cholecystokinin levels throughout the lipopolysaccharide-induced inflammatory response. Lipid- and protein-rich nutrition attenuated circulating levels of the proinflammatory cytokines tumor necrosis factor-α and interleukin-6 and the interleukin-1 receptor antagonist compared with control nutrition (all p < 0.05) and fasted subjects (all p < 0.05). In additional, lipid- and protein-rich nutrition augmented the anti-inflammatory response, reflected by increased plasma levels of interleukin-10 compared with fasted subjects (p < 0.0001). CONCLUSIONS: The current preclinical study expands the immunomodulating effects of enteral nutrition as previously observed in rodents to man. Continuous administration of enteral nutrition resulted in a rapid anti-inflammatory effect. Furthermore, enrichment of the nutritional composition with lipid and protein was shown to enhance the anti-inflammatory potential. Therefore, continuous enteral administration of lipid- and protein-rich nutrition is a promising intervention to modulate the immune response in the early course of systemic inflammation in man.

Deficient Candida-specific T-helper 17 response during sepsis.

Patients with sepsis in the intensive care unit (ICU) are prone to develop Candida infections. Here, we investigated Candida-induced T-helper 17 (Th17) responses during experimental human endotoxemia and in patients with sepsis admitted to the ICU. Peripheral blood mononuclear cells were stimulated with Candida albicans. The Th17 response was significantly lower during endotoxemia, compared with baseline. Patients with gram-negative sepsis had a significantly lower Th17 response as compared to healthy controls. These data demonstrate that the Th17 response is deficient during endotoxin-related systemic inflammation, which likely represents an important risk factor for increased susceptibility to develop Candida infection in patients with sepsis.

How systemic inflammation modulates adenosine metabolism and adenosine receptor expression in humans in vivo.

OBJECTIVE: Adenosine modulates inflammation and prevents associated organ injury by activation of its receptors. During sepsis, the extracellular adenosine concentration increases rapidly, but the underlying mechanism in humans is unknown. We aimed to determine the changes in adenosine metabolism and signaling both in vivo during experimental human endotoxemia and in vitro. DESIGN: We studied subjects participating in three different randomized double-blind placebo-controlled trials. In order to prevent confounding by the different pharmacological interventions in these trials, analyses were performed on data of placebo-treated subjects only. SETTING: Intensive care research unit at the Radboud University Nijmegen Medical Center. SUBJECTS: In total, we used material of 24 healthy male subjects. INTERVENTIONS: Subjects received 2 ng/kg Escherichia coli endotoxin (lipopolysaccharide) intravenously. MEASUREMENTS AND MAIN RESULTS: Following experimental endotoxemia, endogenous adenosine concentrations increased. Expression of 5'ectonucleotidase messenger RNA was upregulated (p = .01), whereas adenosine deaminase messenger RNA was downregulated (p = .02). Furthermore, both adenosine deaminase and adenosine kinase activity was significantly diminished (both p ≤ .0001). A2a and A2b receptor messenger RNA expression was elevated (p = .02 and p = .04, respectively), whereas messenger RNA expression of A1 and A3 receptors was reduced (both, p = .03). In vitro, lipopolysaccharide dose-dependently attenuated the activity of both adenosine deaminase and adenosine kinase (both p ≤ .0001). CONCLUSIONS: Adenosine metabolism and signaling undergo adaptive changes during human experimental endotoxemia promoting higher levels of adenosine thereby facilitating its inflammatory signaling.

Functional and genetic evidence that the Mal/TIRAP allele variant 180L has been selected by providing protection against septic shock.

Adequate responses by our innate immune system toward invading pathogens were of vital importance for surviving infections, especially before the antibiotic era. Recently, a polymorphism in Mal (Ser180Leu, TIRAP rs8177374), an important adaptor protein downstream of the Toll-like receptor (TLR) 2 and 4 pathways, has been described to provide protection against a broad range of infectious pathogens. We assessed the functional effects of this polymorphism in human experimental endotoxemia, and we demonstrate that individuals bearing the TIRAP 180L allele display an increased, innate immune response to TLR4 and TLR2 ligands, but not to TLR9 stimulation. This phenotype has been related to an increased resistance to infection. However, an overshoot in the release of proinflammatory cytokines by TIRAP 180L homozygous individuals suggests a scenario of balanced evolution. We have also investigated the worldwide distribution of the Ser180Leu polymorphism in 14 populations around the globe to correlate the genetic makeup of TIRAP with the local infectious pressures. Based on the immunological, clinical, and genetic data, we propose that this mutation might have been selected in West Eurasia during the early settlement of this region after the out-of-Africa migration of modern Homo sapiens. This combination of functional and genetic data provides unique insights to our understanding of the pathogenesis of sepsis.

Differential ex vivo and in vivo endotoxin tolerance kinetics following human endotoxemia.

OBJECTIVES: Endotoxin (lipopolysaccharide) tolerance is characterized by a transient refractory state to a subsequent lipopolysaccharide challenge. Following human endotoxemia, ex vivo tolerance of circulating leukocytes to lipopolysaccharide resolves within 24 hrs. However, the duration of in vivo tolerance, assumed to be primarily mediated by tissue-resident macrophages, is unknown. DESIGN, SETTING, SUBJECTS, AND INTERVENTIONS: Clinical experimental study in 16 healthy male volunteers at an intensive care research unit. To compare ex vivo and in vivo tolerance kinetics, whole blood from healthy volunteers was stimulated with lipopolysaccharide before, 4 hrs after, and 1, 2, 3, and 4 wks following in vivo endotoxin (2 ng/kg; lipopolysaccharide derived from Escherichia coli O:113) administration. Furthermore, we compared the inflammatory response during two subsequent endotoxemia experiments in healthy volunteers with an interval of 2 wks. The cytokines tumor necrosis factor-α, interleukin-6, interleukin-10, interleukin-1 receptor antagonist, and transforming growth factor-ß were measured. MEASUREMENTS AND MAIN RESULTS: Four hours after in vivo lipopolysaccharide administration, production of tumor necrosis factor-α, interleukin-6, and interleukin-10, but not interleukin-1 receptor antagonist in ex vivo lipopolysaccharide-stimulated whole blood was diminished. Ex vivo lipopolysaccharide tolerance completely resolved within 1 week. In contrast, in vivo lipopolysaccharide tolerance was still apparent after 2 wks. Compared to the first lipopolysaccharide administration, plasma peak levels of tumor necrosis factor-α, interleukin-6, interleukin-10, interleukin-1 receptor antagonist, and transforming growth factor-ß were attenuated by 46%, 36%, 45%, 10%, and 14%, respectively (all p < .05). CONCLUSIONS: While ex vivo lipopolysaccharide tolerance quickly resolves, in vivo lipopolysaccharide tolerance persists for at least 2 wks. These findings strengthen the notion that the in vivo response to lipopolysaccharide is mediated by tissue-resident macrophages and that ex vivo stimulation does not accurately reflect the in vivo innate immune response. Intervention studies utilizing the human endotoxemia model should be performed using parallel groups rather than a crossover design.

Dipyridamole augments the antiinflammatory response during human endotoxemia.

INTRODUCTION: In animal models of systemic inflammation, the endogenous nucleoside adenosine controls inflammation and prevents organ injury. Dipyridamole blocks the cellular uptake of endogenous adenosine and increases the extracellular adenosine concentration. We studied the effects of oral dipyridamole treatment on innate immunity and organ injury during human experimental endotoxemia. METHODS: In a randomized double-blind placebo-controlled study, 20 healthy male subjects received 2 ng/kg Escherichia coli endotoxin (lipopolysaccharide; LPS) intravenously after 7-day pretreatment with dipyridamole, 200 mg slow release twice daily, or placebo. RESULTS: Nucleoside transporter activity on circulating erythrocytes was reduced by dipyridamole with 89% ± 2% (P < 0.0001), and the circulating endogenous adenosine concentration was increased. Treatment with dipyridamole augmented the LPS-induced increase in the antiinflammatory cytokine interleukin (IL)-10 with 274%, and resulted in a more rapid decrease in proinflammatory cytokines tumor necrosis factor-α (TNF-α) and IL-6 levels directly after their peak level (P < 0.05 and < 0.01, respectively). A strong correlation was found between the plasma dipyridamole concentration and the adenosine concentration (r = 0.82; P < 0.01), and between the adenosine concentration and the IL-10 concentration (r = 0.88; P < 0.0001), and the subsequent decrease in TNF-α (r = -0.54; P = 0.02). Dipyridamole treatment did not affect the LPS-induced endothelial dysfunction or renal injury during experimental endotoxemia. CONCLUSIONS: Seven-day oral treatment with dipyridamole increases the circulating adenosine concentration and augments the antiinflammatory response during experimental human endotoxemia, which is associated with a faster decline in proinflammatory cytokines. TRIAL REGISTRATION: ClinicalTrials (NCT): NCT01091571.

Circulating adenosine increases during human experimental endotoxemia but blockade of its receptor does not influence the immune response and subsequent organ injury.

INTRODUCTION: Preclinical studies have shown that the endogenous nucleoside adenosine prevents excessive tissue injury during systemic inflammation. We aimed to study whether endogenous adenosine also limits tissue injury in a human in vivo model of systemic inflammation. In addition, we studied whether subjects with the common 34C > T nonsense variant (rs17602729) of adenosine monophosphate deaminase (AMPD1), which predicts increased adenosine formation, have less inflammation-induced injury. METHODS: In a randomized double-blinded design, healthy male volunteers received 2 ng/kg E. Coli LPS intravenously with (n = 10) or without (n = 10) pretreatment with the adenosine receptor antagonist caffeine (4 mg/kg body weight). In addition, lipopolysaccharide (LPS) was administered to 10 subjects heterozygous for the AMPD1 34C > T variant. RESULTS: The increase in adenosine levels tended to be more pronounced in the subjects heterozygous for the AMPD1 34C > T variant (71 ± 22%, P=0.04), compared to placebo- (59 ± 29%, P=0.012) and caffeine-treated (53 ± 47%, P=0.29) subjects, but this difference between groups did not reach statistical significance. Also the LPS-induced increase in circulating cytokines was similar in the LPS-placebo, LPS-caffeine and LPS-AMPD1-groups. Endotoxemia resulted in an increase in circulating plasma markers of endothelial activation [intercellular adhesion molecule (ICAM) and vascular cell adhesion molecule (VCAM)], and in subclinical renal injury, measured by increased urinary excretion of tubular injury markers. The LPS-induced increase of these markers did not differ between the three groups. CONCLUSIONS: Human experimental endotoxemia induces an increase in circulating cytokine levels and subclinical endothelial and renal injury. Although the plasma adenosine concentration is elevated during systemic inflammation, co-administration of caffeine or the presence of the 34C > T variant of AMPD1 does not affect the observed subclinical organ damage, suggesting that adenosine does not affect the inflammatory response and subclinical endothelial and renal injury during human experimental endotoxemia. TRIAL REGISTRATION: ClinicalTrials (NCT): NCT00513110.

Endotoxemia-induced inflammation and the effect on the human brain.

INTRODUCTION: Effects of systemic inflammation on cerebral function are not clear, as both inflammation-induced encephalopathy as well as stress-hormone mediated alertness have been described. METHODS: Experimental endotoxemia (2 ng/kg Escherichia coli lipopolysaccharide [LPS]) was induced in 15 subjects, whereas 10 served as controls. Cytokines (TNF-alpha, IL-6, IL1-RA and IL-10), cortisol, brain specific proteins (BSP), electroencephalography (EEG) and cognitive function tests (CFTs) were determined. RESULTS: Following LPS infusion, circulating pro- and anti-inflammatory cytokines, and cortisol increased (P < 0.0001). BSP changes stayed within the normal range, in which neuron specific enolase (NSE) and S100-beta changed significantly. Except in one subject with a mild encephalopathic episode, without cognitive dysfunction, endotoxemia induced no clinically relevant EEG changes. Quantitative EEG analysis showed a higher state of alertness detected by changes in the central region, and peak frequency in the occipital region. Improved CFTs during endotoxemia was found to be due to a practice effect as CFTs improved to the same extent in the reference group. Cortisol significantly correlated with a higher state of alertness detected on the EEG. Increased IL-10 and the decreased NSE both correlated with improvement of working memory and with psychomotor speed capacity. No other significant correlations between cytokines, cortisol, EEG, CFT and BSP were found. CONCLUSIONS: Short-term systemic inflammation does not provoke or explain the occurrence of septic encephalopathy, but primarily results in an inflammation-mediated increase in cortisol and alertness. TRIAL REGISTRATION: NCT00513110.

[The Waterhouse-Friderichsen syndrome]. / Het syndroom van Waterhouse-Friderichsen.

BACKGROUND: The Waterhouse-Friderichsen syndrome (WFS) is a serious illness associated with a high mortality rate and characterized by septic shock and signs of adrenocortical insufficiency. CASE DESCRIPTION: A 33-year-old male was seen in the emergency department with severe abdominal and back pain with diffuse mottled skin and rapidly progressive petechiae all over his body. Laboratory results showed severe lactate acidosis with renal dysfunction and indications of diffuse intravascular coagulation. Because he had signs of progressive septic shock, the patient was admitted to the ICU. There he subsequently developed hypoglycaemia (glucose < 0.1 mmol/l) and CPR had to be performed twice - the patient died shortly afterwards. Autopsy showed bilateral necrosis and haemorrhage of the adrenal glands, indicative of the diagnosis of WFS. Streptococcus pneumoniae was identified. CONCLUSION: In case of sepsis, with fever, rapidly expanding petechiae and purpura the Waterhouse-Friderichsen syndrome should be considered. Intensive therapy with antibiotics, fluids, vasopressors, and corticosteroids should be initiated immediately.

Annexin A5 scintigraphy of forearm as a novel in vivo model of skeletal muscle preconditioning in humans.

BACKGROUND: Nonlethal ischemia and reperfusion reduce ischemia-reperfusion-induced cell death, a phenomenon called ischemic preconditioning. In animal models, this potent endogenous protection is mimicked in vivo by administration of adenosine. In humans, exploitation of ischemic preconditioning is hindered by the lack of an appropriate in vivo model to study this phenomenon. To solve this problem, we aimed to set up an easy-to-use human in vivo model to study ischemic or pharmacological preconditioning. METHODS AND RESULTS: Healthy male volunteers performed unilateral ischemic handgrip. At reperfusion, we intravenously injected technetium-99m-labeled Annexin A5, a presumed marker of ischemic injury, and we imaged both forearms and hands simultaneously with a gamma camera. Region of interest analysis (counts per pixel) and subsequent calculation of the percentage difference in radioactivity between experimental and control hands (thenar muscle; mean+/-SE) revealed significant uptake to the ischemically exercised tissue (26+/-3% at 4 hours after reperfusion; P<0.05). This selective localization of Annexin A5 was reduced by ischemic preconditioning (10 minutes of ischemia plus reperfusion before ischemic exercise) or by infusion of adenosine into the brachial artery to 6+/-1% and 10+/-3%, respectively (P<0.05 versus ischemic exercise alone), resembling observations in animal models with infarct size as an end point. Appropriate control experiments supported our conclusion. CONCLUSIONS: Annexin A5 scintigraphy can be applied to test pharmacological or physiological interventions for their ability to prevent ischemia-reperfusion injury.

Oral therapy with dipyridamole limits ischemia-reperfusion injury in humans.

BACKGROUND: Adenosine receptor stimulation induces several effects that could limit ischemia-reperfusion injury. We hypothesize that treatment with the nucleoside uptake inhibitor dipyridamole increases endogenous adenosine and limits ischemia-reperfusion injury in humans. METHODS: Ischemia-reperfusion injury was studied in forearm skeletal muscle by technetium Tc 99m-labeled annexin A5 scintigraphy. Ischemia-reperfusion injury was induced by unilateral forearm ischemic exercise. Immediately on reperfusion, annexin A5 labeled with technetium Tc 99m was administered intravenously, and ischemia-reperfusion injury was expressed as the percentage difference in radioactivity between the experimental arm and the control arm 1 and 4 hours after reperfusion. Targeting was quantified in the region of the thenar muscle and forearm flexor muscles. This approach was used in 9 healthy male volunteers after a 1-week treatment with dipyridamole (200 mg, slow release, twice daily) and in 23 control subjects. RESULTS: Dipyridamole treatment significantly reduced annexin A5 targeting in skeletal muscle compared with the control group (thenar region, 13% +/- 7% versus 22% +/- 15% at 1 hour after reperfusion and 9% +/- 6% versus 27% +/- 13% at 4 hours for dipyridamole and control groups, respectively [P = .01]; flexor region, 4% +/- 8% versus 7% +/- 6% at 1 hour after reperfusion and 1% +/- 4% versus 10% +/- 9% at 4 hours for dipyridamole and control groups, respectively [P = .01]). CONCLUSIONS: One week of oral treatment with the nucleoside uptake inhibitor dipyridamole (200 mg, slow release, twice daily) significantly limits ischemia-reperfusion injury in humans in vivo, as assessed by technetium Tc 99m-labeled annexin A5 scintigraphy of forearm skeletal muscle.

[Pneumorachis and pneumopericardium after ecstasy use: an uncommon complication]. / Pneumorachis en pneumopericardium na ecstasygebruik: een niet alledaagse complicatie.

BACKGROUND: Over the past few years there has been an increase in the use of ecstasy among the Dutch population. A number of complications are associated with this drug, hyperthermia being the most well-known. A less commonly-occurring complication is pneumomediastinum. CASE DESCRIPTION: A 20-year-old man presented at the emergency department with extensive subcutaneous emphysema, pneumomediastinum, pneumopericardium and pneumorachis (air within the spinal canal), which had developed after visiting a festival. After excluding the most likely causes, it was concluded that it was due to a combination of ecstasy use and intensive activity (dancing). He was managed conservatively and after two days of observation in the ICU the patient fully recovered. CONCLUSION: This case illustrates a rare complication that seems - indirectly - related to using ecstasy. In most cases conservative treatment is adequate but the presence of pneumopericardium means that given the risk of cardiovascular complications, cardiopulmonary monitoring is essential to trace them.

[Leptospirosis]. / Leptospirose.

Leptospirosis is a zoonosis caused by pathogenic Leptospira species. Leptospira infection can range from subclinical to life-threatening disease. Renal failure and severe respiratory symptoms may occur and are associated with a high mortality rate. It is important to realise that renal failure and other symptoms can occur in the absence of icterus. Leptospiraemia occurs mostly during the first week of acute illness, so blood cultures should be taken as soon as possible. Most cases of leptospirosis are diagnosed by serology. Antibodies are detectable in the blood approximately 5 to 7 days after onset of symptoms. Early recognition and treatment with either cephalosporins or penicillin may shorten the duration and severity of multi-organ failure and is therefore mandatory.

Inflammation-induced increases in plasma endocan levels are associated with endothelial dysfunction in humans in vivo.

Although endothelial dysfunction is central to the pathogenesis of sepsis, no specific and clinically applicable marker for endothelial dysfunction is currently available. Endocan, a proteoglycan excreted by endothelial cells in response to inflammatory cytokines, may serve as such a marker. Our objective was to investigate the kinetics of endocan and its relationship with inflammation-induced endothelial dysfunction during experimental human endotoxemia. Endothelial function was assessed in 17 healthy male volunteers before and 4 h after the administration of 2 ng/kg lipopolysaccharide (LPS) by determination of the vasodilatory response of forearm blood vessels to intra-arterial infusion of endothelium-dependent (acetylcholine) or endothelium-independent (nitroglycerin/sodium nitroprusside) vasodilators using venous occlusion plethysmography. Plasma levels of endocan, inflammatory cytokines, intercellular adhesion molecule (ICAM), and vascular cell adhesion molecule (VCAM) were measured, and correlations with endothelial dysfunction were explored. Plasma levels of all measured cytokines, endocan, ICAM, and VCAM concentrations significantly increased after LPS administration. Furthermore, LPS administration resulted in a significantly blunted response to acetylcholine (mean ± SD increase in forearm blood flow [FBF] of 383% ± 320% before LPS vs. 173% ± 134% after LPS, P = 0.03), whereas the response to nitroglycerin/sodium nitroprusside was not affected (mean ± SD increase in FBF of 174% ± 120% before LPS vs. 110% ± 82% after LPS, P = 0.11). Furthermore, there was a significant correlation between the increase in plasma endocan levels and the attenuation of vasodilatory responses to acetylcholine (r = -0.48, P < 0.05). No correlation existed between plasma levels of ICAM or VCAM and the attenuation of the acetylcholine-induced vasodilatory response. Endocan levels are related to endothelial dysfunction in humans in vivo during systemic inflammation evoked by experimental endotoxemia. Therefore, this study suggests that endocan could be a novel marker of endothelial dysfunction in inflammatory conditions.

Effects of the 34C>T Variant of the AMPD1 Gene on Immune Function, Multi-Organ Dysfunction, and Mortality in Sepsis Patients.

INTRODUCTION: Adenosine exerts anti-inflammatory and tissue-protective effects during systemic inflammation. While the tissue-protective effects might limit organ damage, its anti-inflammatory properties may induce immunoparalysis and impede bacterial clearance. The common 34C>T loss-of-function variant of AMPD1 (rs17602729) is associated with increased adenosine formation, but effects on immune function and outcome in sepsis patients are unknown. METHODS: The effects of the presence of the 34C>T variant on sepsis susceptibility, immune function, multi-organ dysfunction, and mortality in septic patients were studied. Patients suffering from community acquired pneumonia (CAP, initial cohort n = 285; replication cohort n = 212) and ventilator-associated pneumonia (VAP, n = 117; n = 33) and control patients without infection (n = 101) were enrolled. Genetic distributions of the AMPD1 SNP were CC 76%, CT 22%, and TT 2% in the initial cohort and CC 80%, CT 18%, and TT 2% in the replication cohort. RESULTS: The occurrence of septic CAP, but not septic VAP, was increased for the CT versus CC genotype (OR (95% CI) 2.0 (1.1-3.7); P = 0.02) in the initial cohort. The increased risk for the CT versus CC genotype was also observed in the replication cohort but did not reach statistical significance there (P = 0.38), resulting in an OR of the total group of 1.7 (95% CI 1.0-3.1), P = 0.07. In septic patients carrying the CT genotype, the ex vivo production of TNF-α by LPS-stimulated monocytes was attenuated (P = 0.005), indicative of a more pronounced immunoparalytic state in these patients. CONCLUSIONS: Presence of the AMPD1 34C>T variant is associated with higher infection susceptibility to CAP, but not to VAP. More pronounced immunoparalysis in these patients mediated by the anti-inflammatory effects of adenosine may account for this observation.

Modulation of innate immunity by adenosine receptor stimulation.

In the past decades, increased concentrations of the signaling molecule adenosine have been shown to play an important role in the prevention of tissue damage evoked by several stressful circumstances. During systemic inflammation, the circulating adenosine concentration increases rapidly, even up to 10-fold in septic shock patients. By binding to specific adenosine receptor subtypes, designated A1, A2a, A2b, and A3, adenosine exerts a wide variety of immunomodulating and (cyto)protective effects. Only recently, several specific adenosine receptor agonists and other drugs that modulate adenosine metabolism have been developed for human use. Importantly, correct interpretation of the effects of adenosine is highly related to the model of inflammation used, e.g., administration of endotoxin or live bacteria. This review will discuss the potential role for adenosine as an immunomodulating and cytoprotective signaling molecule and will discuss its potential role in the treatment of the patient suffering from sepsis.

Interplay between the acute inflammatory response and heart rate variability in healthy human volunteers.

The autonomic nervous system and the inflammatory response are intimately linked. Heart rate variability (HRV) analysis is a widely used method to assess cardiac autonomic nervous system activity, and changes in HRV indices may correlate with inflammatory markers. Here, we investigated whether baseline HRV predicts the acute inflammatory response to endotoxin. Second, we investigated whether the magnitude of the inflammatory response correlated with HRV alterations. Forty healthy volunteers received a single intravenous bolus of 2 ng/kg endotoxin (LPS, derived from Escherichia coli O:113). Of these, 12 healthy volunteers were administered LPS again 2 weeks later. Heart rate variability was determined at baseline (just before LPS administration) and hourly thereafter until 8 h after LPS administration. Plasma cytokine levels were determined at various time points. Baseline HRV indices did not correlate with the magnitude of the LPS-induced inflammatory response. Despite large alterations in HRV after LPS administration, the extent of the inflammatory response did not correlate with the magnitude of HRV changes. In subjects who were administered LPS twice, inflammatory cytokines were markedly attenuated after the second LPS administration, whereas LPS-induced HRV alterations were similar. Heart rate variability indices do not predict the acute inflammatory response in a standardized model of systemic inflammation. Although the acute inflammatory response results in HRV changes, no correlations with inflammatory cytokines were observed. Therefore, the magnitude of endotoxemia-related HRV changes does not reflect the extent of the inflammatory response.

Functional heterogeneity and differential priming of circulating neutrophils in human experimental endotoxemia.

Neutrophils play an important role in host defense. However, deregulation of neutrophils contributes to tissue damage in severe systemic inflammation. In contrast to complications mediated by an overactive neutrophil compartment, severe systemic inflammation is a risk factor for development of immune suppression and as a result, infectious complications. The role of neutrophils in this clinical paradox is poorly understood, and in this study, we tested whether this paradox could be explained by distinct neutrophil subsets and their functionality. We studied the circulating neutrophil compartment immediately after induction of systemic inflammation by administering 2 ng/kg Escherichia coli LPS i.v. to healthy volunteers. Neutrophils were phenotyped by expression of membrane receptors visualized by flow cytometry, capacity to interact with fluorescently labeled microbes, and activation of the NADPH-oxidase by oxidation of Amplex Red and dihydrorhodamine. After induction of systemic inflammation, expression of membrane receptors on neutrophils, such as CXCR1 and -2 (IL-8Rs), C5aR, FcgammaRII, and TLR4, was decreased. Neutrophils were also refractory to fMLF-induced up-regulation of membrane receptors, and suppression of antimicrobial function was shown by decreased interaction with Staphylococcus epidermis. Simultaneously, activation of circulating neutrophils was demonstrated by a threefold increase in release of ROS. The paradoxical phenotype can be explained by the selective priming of the respiratory burst. In contrast, newly released, CD16(dim) banded neutrophils display decreased antimicrobial function. We conclude that systemic inflammation leads to a functionally heterogeneous neutrophil compartment, in which newly released refractory neutrophils can cause susceptibility to infections, and activated, differentiated neutrophils can mediate tissue damage.

Inflammation-induced hepatotoxicity in humans.

Because severe sepsis is frequently complicated by multiple organ failure, it is of importance to monitor organ function. Unfortunately, conventional liver function markers are either relatively unspecific or have a long half-life, which make them poor predictors of acute liver injury. Glutathione S-transferase A1-1 (GSTA1-1) has a relatively short half-life (1 h), is more specific, and is rapidly released into the blood after liver damage. In the present study, we measured plasma GSTA1-1 levels by enzyme-linked immunosorbent assay in seven healthy volunteers after repeated experimental endotoxemia induced by 2 ng kg Escherichia coli endotoxin per day (to investigate inflammation-induced hepatic injury) and in 21 patients within 12 h after the occurrence of severe sepsis/septic shock (to investigate its ability to predict an increase of transaminases on day 7). During repeated experimental endotoxemia in healthy volunteers, TNF-alpha and IL-6 levels increased from undetectable levels to 1,425 (474-1,949) and 1,739 (989-2,047) pg mL, respectively, whereas GSTA1-1 levels did not exceed the normal range, indicating that no (sub)clinical liver injury occurs in this model of inflammation. In septic patients, GSTA1-1 levels had a specificity of 88%, resulting in a positive predictive value for liver injury of 86% and a positive likelihood ratio of 6 to indicate an increase in transaminases on day 7. Furthermore, GSTA1-1 levels did not correlate with IL-6 levels but did with dobutamine infusion rate (Spearman r = 0.94; P = 0.02), suggesting that the extent of hemodynamic instability and not the degree of inflammation could be of importance for the occurrence of liver damage. In septic shock patients, GSTA1-1 may represent a useful marker for early liver injury.