Dobutamine does not influence inflammatory pathways during human endotoxemia

OBJECTIVE: Catecholamines have anti-inflammatory and anticoagulant properties. Dobutamine is a synthetic catecholamine frequently used in patients with septic myocardial dysfunction. The objective was to determine whether a continuous infusion of dobutamine exerts immunomodulatory effects in healthy volunteers challenged with endotoxin. DESIGN: Prospective, open-label study. SETTING: Clinical research unit of a university hospital. PARTICIPANTS: Sixteen male healthy volunteers. INTERVENTIONS: Volunteers received a constant infusion with dobutamine (10 microg.kg.min, n = 8) or physiologic saline (n = 8). All participants were challenged with a bolus injection of endotoxin prepared from Escherichia coli (4 ng/kg). Dobutamine infusion was commenced 1 hr before endotoxin challenge and was continued until 3 hrs thereafter. MEASUREMENTS AND MAIN RESULTS: Dobutamine infusion was associated with an increase in mean arterial blood pressure (peak 122 +/- 5 mm Hg) and heart rate (peak 84 +/- 4 beats/min, both p < .05 vs. saline). Endotoxin injection induced the systemic release of cytokines (tumor necrosis factor-alpha, interleukins-6, -8, and -10) and secretory phospholipase A2, endothelial cell activation (increase in the plasma levels of soluble E-selectin and von Willebrand factor), activation of coagulation (increased plasma levels of soluble tissue factor, F1 + 2 prothrombin fragment, and thrombin-antithrombin complexes), and activation with subsequent inhibition of fibrinolysis (increased plasma concentrations of tissue-type plasminogen activator, plasminogen activator inhibitor type I, and plasmin-alpha2-antiplasmin complexes). None of these responses were influenced by dobutamine. CONCLUSIONS: Dobutamine, infused in a clinically relevant dose, does not influence inflammatory and coagulant pathways during human endotoxemi

Stimulation of alpha 7 cholinergic receptors inhibits lipopolysaccharide-induced neutrophil recruitment by a tumor necrosis factor alpha-independent mechanism

The cholinergic nervous system controls inflammation by inhibiting the release of proinflammatory cytokines such as tumor necrosis factor (TNF) alpha from lipopolysaccharide (LPS)-stimulated macrophages. The key endogenous mediator of this so-called cholinergic anti-inflammatory pathway is acetylcholine, the principal neurotransmitter of the vagus nerve, which specifically interacts with alpha7 cholinergic receptors expressed by macrophages and other cell types to inhibit TNF-alpha production. We here investigated the capacity of the selective alpha7 cholinergic receptor agonist 3-(2,4-dimethoxybenzylidene) anabaseine (GTS-21) to inhibit LPS-induced inflammatory responses in mice in vivo. To this end, mice received an intraperitoneal injection of LPS (from Escherichia coli, 200 microg) preceded by GTS-21 (4 mg/kg) or vehicle. GTS-21 strongly inhibited LPS-induced TNF-alpha release into the peritoneal cavity and the circulation. In addition, GTS-21 attenuated the influx of neutrophils into peritoneal fluid upon administration of LPS. This inhibitory effect on neutrophil recruitment by GTS-21 was independent of its effect on TNF-alpha release, considering that etanercept, a potent TNF-alpha-blocking protein containing the extracellular domain of the p75 TNF-alpha receptor, did not influence LPS-induced neutrophil influx either in the presence or in the absence of GTS-21 treatment. GTS-21 did not reduce the local secretion of macrophage inflammatory protein 2 and keratinocyte-derived cytokine, suggesting that altered concentrations of these neutrophil-attracting chemokines did not contribute to GTS-21-induced inhibition of neutrophil migration. These data identify a novel anti-inflammatory effect of chemical alpha7 cholinergic receptor stimulation that is independent from its capacity to inhibit TNF-alpha productio

Differential dose-dependent effects of prednisolone on shedding of endothelial adhesion molecules during human endotoxemia

Low dose prednisolone was shown to be beneficial in the treatment of the Acute respiratory distress syndrome (ARDS) and septic shock. One corticosteroid-induced effect, postulated to mediate corticosteroid-induced anti-inflammatory effects, is decreased expression of adhesion molecules on endothelial cells, thereby preventing leukocyte recruitment at inflammatory sites. The current study aimed to investigate the effect of increasing doses of prednisolone on the release of soluble adhesion molecules in healthy volunteers challenged with endotoxin. Therefore, 32 healthy, male volunteers received prednisolone orally at doses of 0mg, 3mg, 10mg or 30mg at 2h before injection of endotoxin prepared from Escherichia coli (4ng/kg) and levels of soluble E-selectin (sE-selectin), soluble VCAM-1 (sVCAM-1) and soluble ICAM-1 (sICAM-1) were measured. Levels of all markers were increased after induction of endotoxemia. Levels of sE-selectin were inhibited by a dose of 3mg prednisolone and levels of sVCAM-1 were decreased after a dose of 10mg. Maximal inhibition of both sE-selectin and sVCAM-1 levels was achieved by the highest dose of prednisolone 30mg. Remarkably, prednisolone 3mg potentiated endotoxin-induced sVCAM-1 release. Levels of sICAM-1 were not affected by prednisolone. Together, the data suggest that prednisolone differentially and dose-dependently influences the release of soluble endothelial adhesion molecules during human endotoxemi

Local stimulation of alpha 7 cholinergic receptors inhibits LPS-induced TNF-alpha release in the mouse lung

The cholinergic nervous system can inhibit the release of proinflammatory cytokines such as TNF-alpha from LPS-stimulated macrophages. Acetylcholine, the principal neurotransmitter of the vagus nerve, is the key mediator of this so-called cholinergic anti-inflammatory pathway, specifically interacting with alpha 7 cholinergic receptors expressed by macrophages and other cell types to inhibit TNF-alpha production. The aim of the current study was to determine the capacity of the selective alpha 7 cholinergic receptor agonist 3-(2,4-dimethoxybenzylidene) anabaseine (GTS-21), administered locally into the airways, to inhibit LPS-induced inflammatory responses in the mouse lung in vivo. GTS-21 dose-dependently inhibited LPS-induced TNF-alpha release by MH-S mouse alveolar macrophages in vitro. Intranasal inoculation with GTS-21 also dose-dependently inhibited TNF-alpha release into the lung compartment after intrapulmonary delivery of LPS in mice in vivo, whereas IL-6 concentrations were not affected. However, GTS-21 did not influence the influx of neutrophils into bronchoalveolar lavage fluid elicited by LPS and increased the concentrations of the neutrophil-attracting chemokines cytokine-induced neutrophil chemoattractant and macrophage inflammatory protein 2. These data indicate that local administration of GTS-21 inhibits TNF-alpha release in the lung during LPS-induced inflammatio

The acute-phase response impairs host defence against Enterococcus faecium peritonitis

Enterococcus faecium is an emerging pathogen that causes infections in hospitalized patients with various co-morbid diseases. These underlying diseases are often associated with an acute-phase response that renders patients vulnerable to nosocomial infections. To study the influence of the acute-phase response induced by sterile tissue injury on host defence against E. faecium, mice were injected subcutaneously with either turpentine or casein 1 day before intraperitoneal infection with E. faecium. Control mice were subcutaneously injected with saline or sodium bicarbonate, respectively. Turpentine and casein induced an acute-phase response as reflected by increases in the plasma concentrations of interleukin-6, serum amyloid P and C3. A pre-existent acute-phase response in mice was associated with a strongly reduced capacity to clear E. faecium, resulting in prolonged bacteraemia for several days. The inflammatory response to E. faecium was impaired in mice with an acute-phase response, as shown by reduced capacity to mount a neutrophilic leucocytosis in peripheral blood and by decreased local cytokine concentrations. These data indicate that the acute-phase response impairs host defence against E. faecium, suggesting that this condition may contribute to the increased vulnerability of critically ill patients to enterococcal infections

Endogenous beta-adrenergic receptors inhibit lipopolysaccharide-induced pulmonary cytokine release and coagulation

beta 2-adrenergic receptors are expressed on different cell types in the lung, including respiratory epithelial cells, smooth muscle cells, and macrophages. The aim of the current study was to determine the role of P-adrenergic receptors in the regulation of lung inflammation induced by instillation via the airways of lipopolysaccharide (LPS) (a constituent of the gram-negative bacterial cell wall) or lipoteichoic acid (LTA) (a component of the gram-positive bacterial cell wall). Mice inhaled the P-adrenergic antagonist propranolol or saline 30 minutes before and 3 hours after intranasal LPS or LTA administration. LPS and LTA induced a profound inflammatory response in the lungs as reflected by an influx of neutrophils and the release of proinflammatory cytokines and chemokines into bronchoalveolar lavage fluid (BALF). Propranolol inhalation resulted in enhanced LPS-induced lung inflammation, which was reflected by a stronger secretion of TNF-alpha, IL-6, and monocyte chemoattractant protein-1 into BALF and by enhanced coagulation activation (thrombin-antithrombin complexes). In LTA-induced lung inflammation, propranolol did not influence cytokine release but potentiated activation of coagulation. Propranolol did not alter neutrophil recruitment in either model. This study suggests that P-adrenergic receptors, which are widely expressed in the lungs, serve as negative regulators of pulmonary cytokine release and coagulation induced by LIPS and less so during LTA-induced pulmonary inflammatio

The influence of corticosteroids on the release of novel biomarkers in human endotoxemia

OBJECTIVE: Sepsis intervention studies need better patient stratification methods, and one way to realize this is the introduction of stable biomarkers. A set of recently developed novel biomarkers, based upon precursor-fragments of short-lived hormones, was previously shown to be increased during sepsis. However, it is not known whether these biomarkers are influenced by sepsis intervention strategies. Therefore we investigated the markers in a model of human endotoxemia intervened by increasing doses of prednisolone. DESIGN AND SETTING: Prospective, open-label study in a specialized clinical research unit of a university hospital. SUBJECTS: Thirty-two healthy male volunteers. INTERVENTIONS: Subjects received prednisolone orally at doses of 0, 3, 10 or 30 mg (n=8 per group) at 2 h before intravenous injection of Escherichia coli lipopolysaccharide (LPS) (4 ng/kg). Blood samples were drawn during 24 h after LPS injection. MEASUREMENTS AND RESULTS: LPS injection caused an increase in levels of midregional pro-adrenomedullin (MR-proADM), midregional pro-atrial natriuretic peptide (MR-proANP), C-terminal pro-arginine-vasopressin (CT-proAVP) and procalcitonin (PCT). Prednisolone caused a dose dependent inhibition of MR-proADM, MR-proANP and CT-proAVP levels. CONCLUSIONS: These results show that a set of novel, highly stable sepsis biomarkers was increased during human endotoxemia and was dose-dependently inhibited by corticosteroid pre-treatmen

Effects of prednisolone on the systemic release of mediators of cell-mediated cytotoxicity during human endotoxemia

Corticosteroids are widely used for the suppression of cell-mediated cytoxicity. This process is mediated by natural killer cells and cytotoxic T lymphocytes, and their activation can be monitored by levels of the chemokines CXCL9 and CXCL10, the degranulation product granzymes A and B, and by levels of secretory phospholipase A2. The current study aimed to determine the effects of increasing doses of prednisolone on the release of these mediators in healthy humans exposed to LPS. Therefore, 32 healthy men received prednisolone orally at doses of 0, 3, 10, or 30 mg (n = 8 per group) at 2 h before intravenous injection of Escherichia coil LPS (4 ng/kg). Prednisolone dose-dependently attenuated the LPS-induced rises in the plasma concentrations of the chemokines CXCL9 and CXCL10, as well as of granzymes A and B levels. CXCL10 and granzyme B release were most sensitive to prednisolone, with a significant inhibition already achieved at the lowest prednisolone dose (3 mg). The levels of secretory phospholipase A2 were increased after LPS administration but were not significantly affected by prednisolone. This study demonstrates that prednisolone differentially inhibits the systemic release of mediators involved in cell-mediated cytotoxicity in humans in viv