endothelin-1 and Bacteremia

Circulating levels of endothelin-1 are increased in sepsis and correlate with severity of disease. A rapid and easy immunoassay has been developed to measure the more stable ET-1 precursor peptides proET-1. The objective of this study was to assess the diagnostic and prognostic value of proET-1 in a prospective cohort of mainly septic patients with community-acquired pneumonia.. We evaluated 281 consecutive patients with community acquired pneumonia. Serum proET-1 plasma levels were measured using a new sandwich immunoassay.. ProET-1 levels exhibited a gradual increase depending on the clinical severity of pneumonia as assessed by the pneumonia severity index (PSI) and the CURB65 scores (p < 0.001 and p < 0.01). The diagnostic accuracy to predict bacteraemia of procalcitonin (AUC 0.84 [95% 0.74-0.93]) was superior than C-reactive protein (AUC 0.67 [95%CI 0.56-0.78]) and leukocyte count (AUC 0.66 [95%CI 0.55-0.78]) and in the range of proET-1(AUC of 0.77 [95%CI 0.67-0.86]). ProET-1 levels on admission were increased in patients with adverse medical outcomes including death and need for ICU admission. ROC curve analysis to predict the risk for mortality showed a prognostic accuracy of proET-1 (AUC 0.64 [95%CI 0.53-0.74]), which was higher than C-reactive protein (AUC 0.51 [95%CI 0.41-0.61]) and leukocyte count (AUC 0.55 [95%CI 0.44-0.65]) and within the range of the clinical severity scores (PSI AUC 0.69 [95%CI 0.61-0.76] and CURB65 0.67 [95%CI 0.57-0.77]) and procalcitonin (AUC 0.59 [95% 0.51-0.67]). ProET-1 determination improved significantly the prognostic accuracy of the CURB65 score (AUC of the combined model 0.69 [95%CI 0.59-0.79]). In a multivariate logistic regression model, only proET1 and the clinical severity scores were independent predictors for death and for the need for ICU admission.. In community-acquired pneumonia, ET-1 precursor peptides correlate with disease severity and are independent predictors for mortality and ICU admission. If confirmed in future studies, proET-1 levels may become another helpful tool for risk stratification and management of patients with community-acquired pneumonia.. ISRCTN04176397.

Topics: Aged; Aged, 80 and over; Bacteremia; Community-Acquired Infections; Endothelin-1; Female; Humans; Immunoassay; Logistic Models; Male; Middle Aged; Multivariate Analysis; Pneumonia; Prognosis; Protein Precursors; Randomized Controlled Trials as Topic; ROC Curve; Severity of Illness Index; Switzerland; Treatment Outcome

Acute lung injury is a common complication of gram-negative sepsis. Pulmonary hypertension and increased lung vascular permeability are central features of lung injury following experimental bacteremia. Platelet-activating factor is a prominent proinflammatory mediator during bacterial sepsis. Our previous studies have demonstrated that exogenous administration of platelet-activating factor (PAF) induces pulmonary edema without causing pulmonary hypertension. Interestingly, inhibition of PAF activity during Escherichia coli bacteremia prevents the development of both pulmonary hypertension and pulmonary edema. These data suggest that PAF contributes to pulmonary hypertension during sepsis, but that this is unlikely to be a direct vascular effect of PAF. The goal of the present study was to investigate the mechanism by which acute E. coli bacteremia induces pulmonary injury and to define the role that PAF plays in this injury. We hypothesized that the effects of PAF on pulmonary hypertension during bacteremia are due to the effects of PAF on other vascular mediators. Several studies suggest that PAF induces the expression of endothelin-1 (ET), a potent peptide vasoconstrictor. Further, our previous studies have implicated ET as a central mediator of systemic vasoconstriction during bacteremia. We therefore sought to assess whether ET is modulated by PAF. E. coli has also been demonstrated to increase endothelial production of nitric oxide (NO), which contributes to maintenance of basal vascular tone in the pulmonary circulation. We hypothesized that PAF might increase pulmonary vascular resistance during bacteremia by activating neutrophils, increasing expression of ET, and decreasing the tonic release of NO. Furthermore, we hypothesized that hypoxic vasoconstriction did not contribute to pulmonary vasoconstriction during the first 120 min of E. coli bacteremia.. Pulmonary artery pressure (PAP), blood pressure (BP), heart rate (HR), and arterial blood gases (ABG) were measured in anesthetized spontaneously breathing adult male Sprague-Dawley rats. E. coli (10(9) CFU/100 g body wt) was injected at t = 0, and hemodynamic data were obtained at 10-min intervals and ABG data at 30-min intervals for a total of 120 min. Sham animals were treated equally but received normal saline in place of E. coli. In treatment groups, a 2.5 mg/kg dose of WEB 2086, a PAF receptor antagonist, was administered intravenously 15 min prior to the onset of sepsis or sham sepsis. The groups were (1) intravenous E. coli (n = 5); (2) intravenous WEB 2086 pretreatment + intravenous E. coli (n = 5); (3) intravenous WEB 2086 alone (n = 5); and (4) intravenous normal saline (n = 6). Nitric oxide metabolites (NOx) and ET concentrations were assayed from arterial serum samples obtained at the end of the protocol. Lung tissue was harvested for measurement of myeloperoxidase (MPO) activity and pulmonary histology.. E. coli bacteremia increased HR, PAP, and respiratory rate early during sepsis (within 20 min), while hypoxemia, hypotension, and hemoconcentration were not manifest until the second hour. Pretreatment with WEB 2086 completely abrogated all of these changes. E. coli bacteremia increased the activity of serum ET, lung MPO, and neutrophil sequestration in the lung parenchyma via a PAF-dependent mechanism. However, the mechanism of increased production of NO appears to be PAF independent.. These data support the hypothesis that E. coli bacteremia rapidly induces pulmonary hypertension stimulated by PAF and mediated at least in part by endothelin-1 and neutrophil activation and sequestration in the lung. Microvascular injury with leak is also mediated by PAF during E. coli bacteremia, but the time course of resultant hypoxemia and hemoconcentration is slower than that of pulmonary hypertension. The contribution of hypoxic vasoconstriction in exacerbating pulmonary hypertension in gram-negative sepsis is probably a late

Topics: Animals; Bacteremia; Endothelin-1; Escherichia coli Infections; Hemodynamics; Hemoglobins; Hypertension, Pulmonary; Male; Neutrophils; Nitric Oxide; Oxygen; Peroxidase; Platelet Activating Factor; Rats; Rats, Sprague-Dawley

To define the profiles of endothelin (ET), both big ET and active 21 amino acid ET (ET 1-21) in the plasma and peritoneal cavity of rats with peritonitis.. Open laboratory study.. University hospital, Norway.. 170 adult male Wistar rats.. Lethal peritonitis was induced by making a 4 mm caecal perforation.. Mortality, together with concentrations of total ET, ET 1-21 (measured by two radioimmunoassays), bacteria, endotoxin, tumor necrosis factor (TNF), interleukin 6 (IL-6), and lactate at baseline, two hours, and then four-hourly intervals for 24 hours.. ET reached its maximum at 8 hours, and had returned to baseline after 24 hours. In the first phase of septicaemia there was more big ET than ET 1-21, but the proportions had equalised by 8 hours. There were higher concentrations of both big ET and ET 1-21 in peritoneal fluid than in plasma.. In rats with peritonitis the profiles of big ET and ET 1-21 closely followed mortality, and blood concentrations of bacteria, endotoxin, TNF, IL-6, and lactate.

Topics: Animals; Bacteremia; Endothelin-1; Endothelins; Gram-Negative Bacterial Infections; Interleukin-6; Lactates; Lactic Acid; Lipopolysaccharides; Male; Peritonitis; Protein Precursors; Radioimmunoassay; Rats; Rats, Wistar; Time Factors; Tumor Necrosis Factor-alpha

Big-endothelin (big-ET) is one of the endothelium-derived vasoactive substances that plays an important role in regulating the vascular tone. Because the role of this agent in bacteremia remains unknown, we investigated whether bacteremia induces the release of big-ET in a subhuman primate model and whether tumor necrosis factor (TNF) is an important mediator of big-ET release. To study this, we infused 8 male baboons (17 to 19 kg body weight) intravenously for 2 hours with Escherichia coli (5 x 10(8) CFU/kg) and observed them for 72 hours. Plasma was obtained at various intervals and assayed for big-ET by using immunoassay. Four bacteremic animals given vehicle only showed a peak big-ET plasma concentration of 15.1 +/- 4.6 fmol/ml at 10 hours, as compared with a baseline concentration of 0.9 +/- 0.5 fmol/ml. Administration of anti-TNF monoclonal antibodies (CB6, 15 mg/kg) 2 hours before E. coli infusion in additional animals prevented the rise in plasma TNF levels (5.7 +/- 2.5 ng/ml versus nondetectable) and significantly (p < 0.01) attenuated the release of big-ET. Hemodynamic measurements revealed the typical pattern of sepsis, with generally more stable circulatory conditions in the anti-TNF-treated animals. Moreover, the mortality rate decreased from 100% to 0% with anti-TNF treatment. These studies, therefore, lead us to conclude that TNF, directly or indirectly through another mediator, plays an important role in the endothelin production/release during bacteremia and that neutralization of circulating TNF appears to be beneficial for improving the survival after bacteremia.

Topics: Animals; Bacteremia; Endothelin-1; Endothelins; Endotoxins; Escherichia coli; Escherichia coli Infections; Hemodynamics; Male; Papio; Protein Precursors; Survival Analysis; Tumor Necrosis Factor-alpha