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OBJECTIVE In the pathogenesis of septic shock, caused by either bacterial toxins or trauma, increased production of multiple proinflammatory mediators, such as phospholipase A(2) (PLA(2)), cytokines, and chemokines, is known to be of major importance. The present study was undertaken to investigate the influence of a newly designed extracellular PLA(2) inhibitor (ExPLI) on synthesis of proinflammatory mediators and mortality rate in a rat sepsis model. DESIGN Prospective, randomized animal study. SETTING Experimental laboratory. SUBJECTS Male Wistar-rats weighing 200-300 g. INTERVENTIONS Mortality was induced by intraperitoneal bolus administration of lipopolysaccharide 15 mg/kg in 22 rats that were pretreated with NaCl or ExPLI (150 mg/kg). Furthermore, nine rats received a sublethal bolus of lipopolysaccharide (7.5 mg/kg) and nine rats received lipotechoic acid (8 mg/kg) simultaneously with or after ExPLI administration. Blood samples were collected from these rats, and cytokine concentrations were assessed by enzyme-linked immunosorbent assay. Lung and kidney were removed for RNA isolation and immunohistological analysis. MEASUREMENTS AND MAIN RESULTS ExPLI treatment significantly reduced lipopolysaccharide-induced mortality of rats (90.9 and 36.4%, p

Acute respiratory distress syndrome (ARDS) is characterized by alterations in microvascular permeability. In ARDS secreted phospholipase A 2 (sPLA 2 ) IB and IIA are found to be highly upregulated. In this study, we therefore investigated the influence of exogenously added sPLA 2 -IB and sPLA 2 -IIA on the production of chemokines and adhesion molecules in lung microvascular endothelial cells (LMVEC). Treatment of LMVEC with sPLA 2 s resulted in a significant increase in the production of chemokines and adhesion molecules due to an increased expression of their mRNA and in an enhanced release of oleic acid. The upregulation of chemokines and adhesion molecules by LPS was stronger in the presence of sPLA 2 . Activation of NF-κB occurred upon stimulation with sPLA 2 . Moreover the MAPkinase pERK seems to be involved since a specific pERK inhibitor, e.g., U0126, but not a p38Kinase inhibitor, e.g., SB203580 prevented sPLA 2 -induced chemokine upregulation. Our data therefore suggest that LMVEC are a highly sensitive target for the direct action of extracellular sPLA 2 s.

1. In acute respiratory distress syndrome (ARDS) induced by endotoxins, a high production of inflammatory mediators by microvascular lung endothelial cells (LMVEC) can be observed. Activation of cells by endotoxins may result in elevated secretion of phospholipase A(2) (sPLA(2)) which is thought to contribute to tissue damage. The present study was undertaken to investigate the role of sPLA(2) in chemokine production in human lung microvascular endothelial cells (LMVEC) stimulated with the endotoxins lipopolysaccharide (LPS) and lipoteichoic acid (LTA). In particular, we investigated the effects of sPLA(2) inhibitors, specifically, the extracellular PLA(2) inhibitors (ExPLIs), composed of N-derivatized phosphatidyl-ethanolamine linked to polymeric carriers, and LY311727, a specific inhibitor of non-pancreatic sPLA(2). 2. ExPLIs markedly inhibited LPS and LTA induced production and mRNA expression of the neutrophile attracting chemokines IL-8, Gro-alpha and ENA-78, as well as of the adhesion molecules ICAM-1 and E-selectin. Concomitantly, ExPLIs inhibited the LPS-induced activation of NF-kappaB by LPS but not its activation by TNF-alpha or IL-1. 3. Endotoxin mediated chemokine production in LMVEC seems not to involve PLA(2) activity, since LPS stimulation was not associated with activation of intracellular or secreted PLA(2). It therefore seems that the inhibitory effect of the ExPLIs was not due to their PLA(2) inhibiting capacity. This was supported by the finding that the LPS-induced chemokine production was not affected by the selective sPLA(2) inhibitor LY311727. 4. It is proposed that the ExPLIs may be considered a prototype of potent suppressors of specific endotoxin-induced inflammatory responses, with potential implications for the therapy of subsequent severe inflammation.

Inflammatory responses during sepsis are determined by leucocyte recruitment into inflamed tissues. Both chemokines and adhesion molecules are believed to be involved in this process. As fractalkine exists as transmembrane protein with cell adhesion properties and as soluble chemotactic factor, the present study was conducted to study the role of fractalkine, produced by microvascular and macrovascular endothelial cells, in neutrophil recruitment. Lung microvascular endothelial cells (LMVECs) stimulated with lipopolysaccharide, tumour necrosis factor-alpha or interleukin-1 (IL-1) produced much more fractalkine compared with the macrovascular human umbilical vein endothelial cells (HUVECs). No differences were found between microvascular endothelial cells of different organs. Chemotactic activity in supernatants was significantly stronger in stimulated LMVEC when compared with HUVEC. Although recombinant fractalkine induced migration of neutrophils, IL-8 and monocyte chemoattractant protein-1 were found to be more strictly required. In vivo fractalkine was strongly upregulated in septic lung and kidney. Our data suggest that fractalkine production per se does not explain the preference for inflammation in the lung of septic patients.

Large quantitaties of inflammatory mediators are released during the course of endotoxaemia. These mediators in turn can stimulate the sympathetic nervous system (SNS) to release catecholamines, which ultimately regulate inflammation-associated impairment in tissue perfusion, myocardial impairment and vasodilatation. Treatment of sepsis is based on surgical and/or antibiotic therapy, appropriate fluid management and application of vasoactive catecholamines. With respect to the latter, discussions on the vasopressor of choice are still ongoing. Over the past decade dopamine has been considered the 'first line' vasopressor and is frequently used to improve organ perfusion and blood pressure. However, there is a growing body of evidence that dopamine has deleterious side effects; therefore, its clinical relevance seems to be more and more questionable. Nevertheless, it has not been convincingly demonstrated that other catecholamines are superior to dopamine in this respect. Apart from its haemodynamic action, dopamine can modulate immune responses by influencing the cytokine network. This leads to inhibition of expression of adhesion molecules, inhibition of cytokine and chemokine production, inhibition of neutrophil chemotaxis and disturbed T-cell proliferation. In the present review we summarize our knowledge of the immunomodulatory effects of dopamine, with an emphasis on the mechanisms by which these effects are mediated.