The current studies demonstrate protective and harmful effects of neutrophils (PMN) during experimental sepsis after cecal ligation and puncture (CLP). It is known that CLP induces signaling defects in blood PMN. When PMN were depleted 12 h after CLP, there were dramatic reductions in levels of bacteremia, evidence for reduced liver and renal dysfunction, sharp reductions in serum levels of cytokines (IL-1beta, IL-6, IL-10, TNF-alpha, and IL-2), and improved survival. In contrast, PMN depletion before CLP resulted in substantial increases in bacteremia and no evidence for attenuation of liver and renal failure dysfunction. These data suggest that at the onset of sepsis, PMN are important in regulating the levels of bacteremia, whereas after the onset of sepsis, as they lose innate immune functions, their presence is associated with higher levels of bacteremia and intensified organ dysfunction.

There is mounting evidence that apoptosis plays a significant role in tissue damage during acute lung injury. To evaluate the role of the apoptosis mediators Fas and FasL in acute lung injury, Fas (lpr)- or FasL (gld)-deficient and wild-type mice were challenged with intrapulmonary deposition of IgG immune complexes. Lung injury parameters ((125)I-albumin leak, accumulation of myeloperoxidase, and wet lung weights) were measured and found to be consistently reduced in both lpr and gld mice. In wild-type mice, lung injury was associated with a marked increase in Fas protein in lung. Inflamed lungs of wild-type mice showed striking evidence of activated caspase-3, which was much diminished in inflamed lungs from lpr mice. Intratracheal administration of a monoclonal Fas-activating antibody (Jo2) in wild-type mice induced MIP-2 and KC production in bronchoalveolar lavage fluids, and a murine alveolar macrophage cell line (MH-S) showed significantly increased MIP-2 production after incubation with this antibody. Bronchoalveolar lavage fluid content of MIP-2 and KC was substantially reduced in lpr mice after lung injury when compared to levels in wild-type mice. These data suggest that the Fas/FasL system regulates the acute lung inflammatory response by positively affecting CXC-chemokine production, ultimately leading to enhanced neutrophil influx and tissue damage.

Acute lung injury is a common complication in critically ill patients. The present study examined possible immunomodulating effects of the volatile anaesthetic sevoflurane on lipopolysaccharide (LPS)-stimulated alveolar epithelial cells (AEC) in vitro.Sevoflurane was applied after the onset of injury, simulating a ''postconditioning'' scenario. Rat AEC were stimulated with LPS for 2 h, followed by a 4-h co-exposure to a CO 2 /air mixture with sevoflurane 2.2 volume %; control cells were exposed to the CO 2 /air mixture only. Cytokineinduced neutrophil chemoattractant-1, monocyte chemoattractant protein-1, intercellular adhesion molecule-1, as well as the potential protective mediators inducible nitric oxide synthase (iNOS)2 and heat shock protein (HSP)-32, were analysed. Additionally, functional assays (chemotaxis, adherence and cytotoxicity assay) were performed.A significant reduction of inflammatory mediators in LPS-stimulated, sevoflurane-exposed AEC was found, leading to reduced chemotaxis, neutrophil adherence and neutrophil-induced AEC killing. While iNOS2 was increased in the sevoflurane group, blocking experiments with iNOS2 inhibitor did not affect sevoflurane-induced decrease of inflammatory mediators and AEC killing. Interestingly, sevoflurane treatment also resulted in an enhanced expression of HSP-32.The data presented in the current study provide strong evidence that anaesthetic postconditioning with sevoflurane mediates cytoprotection in the respiratory compartment in an in vitro model of acute lung injury.

Respiratory epithelial cells play a crucial role in the inflammatory response in endotoxin-induced lung injury, an experimental model for acute lung injury. To determine the role of epithelial cells in the upper respiratory compartment in the inflammatory response to endotoxin, we exposed tracheobronchial epithelial cells (TBEC) to lipopolysaccharide (LPS). Expression of inflammatory mediators was analyzed, and the biological implications were assessed using chemotaxis and adherence assays. Epithelial cell necrosis and apoptosis were determined to identify LPS-induced cell damage. Treatment of TBEC with LPS induced enhanced protein expression of cytokines and chemokines (increases of 235-654%, P < 0.05), with increased chemotactic activity regarding neutrophil recruitment. Expression of the intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) was enhanced by 52-101% (P < 0.0001). This upregulation led to increased adhesion of neutrophils, with >95% adherence to TBEC after LPS stimulation, which could be blocked by either ICAM-1 (69%) or VCAM-1 antibodies (55%) (P < 0.05). Enhanced neutrophil-induced necrosis of TBEC was observed when TBEC were exposed to LPS. Reduced neutrophil adherence by ICAM-1 or VCAM-1 antibodies resulted in significantly lower TBEC death (52 and 34%, respectively, P < 0.05). Therefore, tight adherence of neutrophils to TBEC appears to promote epithelial cell killing. In addition to indirect effector cell-induced TBEC death, direct LPS-induced cell damage was seen with increased apoptosis rate in LPS-stimulated TBEC (36% increase of caspase-3, P < 0.01). These data provide evidence that LPS induces TBEC killing in a necrosis- and apoptosis-dependent manner.

Highest possible flow rate, smaller sized syringes and syringe plungers with reduced compressibility should be preferred in order to avoid significant start-up delays in fluid delivery.