Nitric oxide donors in sepsis: a systematic review of clinical and in vivo preclinical data.

An abundant literature in the field of sepsis focuses on the role of NO. Inhibiting NO synthesis corrects certain hemodynamic parameters of septic shock but failed to improve outcome in patients. Conversely, administration of NO donors lowers blood pressure but restores microcirculatory flow in patients with sepsis. We undertook a systematic review of the literature to comprehensively summarize the results of studies exploring the effects of systemic NO donors in sepsis. We included both clinical and preclinical data. We described the details surrounding NO donor administration, and the results obtained in each study were regrouped in broad categories. In the case of animal research, we limited our data collection to in vivo protocols and described the sepsis model. Finally, we critically appraised all the studies included in the review. Overall, the reviewed publications aimed for physiopathological description rather than clinical relevance and did not meet the required criteria for extrapolation to clinical practice. With this reserve, NO donors usually improved the outcomes measured (e.g., mortality, pulmonary hypertension, tissue/organ perfusion, etc.) but also lowered blood pressure. We conclude that our findings warrant further animal experimentation designed to maximize clinical relevance.

Ron receptor tyrosine kinase-dependent hepatic neutrophil recruitment and survival benefit in a murine model of bacterial peritonitis.

OBJECTIVE: To determine whether Ron receptor tyrosine kinase signaling affects the in vivo response to bacterial peritonitis. DESIGN: Experimental study. SETTING: University laboratory. SUBJECTS: Male mice 8-11 wks of age (22-28 g). INTERVENTIONS: A genetic approach comparing wild-type mice to mice with a targeted deletion of the Ron tyrosine kinase signaling domain (TK-/-) was undertaken to determine the influence of Ron receptor in the in vivo response to a well-characterized model of bacterial peritonitis and sepsis induced by cecal ligation and puncture. MEASUREMENTS AND MAIN RESULTS: Several clinical (i.e., survival curves, blood and tissue bacterial burdens, and neutrophil oxidative burst), morphologic (i.e., liver histology and leukocyte trafficking), and biochemical variables (i.e., serum aminotransferases and select serum cytokine and chemokine levels) important for assessing inflammatory responses to bacterial infection were assessed in mice following cecal ligation and puncture. Ron TK-/- mice had a significant decrease in survival time compared with controls, and this was associated with a significant increase in bacterial colony-forming units found in the blood and several end-organs. Moreover, this increased bacterial load was associated with increased liver necrosis and serum alanine aminotransferase levels. Neutrophils isolated from TK-/- mice exhibited decreased spontaneous oxidative burst capacity ex vivo, and by intravital microscopy, a reduced level of neutrophil migration to and translocation within the liver was observed. Loss of Ron signaling resulted in significantly reduced production of serum monocyte chemoattractant protein-1 and interleukin-6 levels following cecal ligation and puncture, and peritoneal macrophage isolated from TK-/- mice exhibited blunted production of monocyte chemoattractant protein-1, interleukin-6, and macrophage inflammatory protein-2 following stimulation with endotoxin ex vivo. CONCLUSIONS: Ron signaling negatively regulates the response to polymicrobial infection by regulating the activation and recruitment of inflammatory cells necessary for clearing a systemic bacterial burden. This effect may be regulated in part through the Ron-dependent, macrophage-mediated production of cytokines and chemokines, namely monocyte chemoattractant protein-1, interleukin-6, and macrophage inflammatory protein-2, important for neutrophil mobilization.

Lung development and susceptibility to ventilator-induced lung injury.

RATIONALE: Ventilator-induced lung injury has been predominantly studied in adults. OBJECTIVES: To explore the effects of age and lung development on susceptibility to such injury. METHODS: Ex vivo isolated nonperfused rat lungs (infant, juvenile, and adult) were mechanically ventilated where VT was based on milliliters per kilogram of body weight or as a percentage of the measured total lung capacity (TLC). In vivo anesthetized rats (infant, adult) were mechanically ventilated with pressure-limited VTs. Allocation to ventilation strategy was randomized. MEASUREMENTS: Ex vivo injury was assessed by pressure-volume analysis, reduction in TLC, and histology, and in vivo injury by lung compliance, cytokine production, and wet- to dry-weight ratio. MAIN RESULTS: Ex vivo ventilation (VT 30 ml.kg(-1)) resulted in a significant reduction (36.0 +/- 10.1%, p < 0.05) in TLC in adult but not in infant lungs. Ex vivo ventilation (VT 50% TLC) resulted in a significant reduction in TLC in both adult (27.8 +/- 2.8%) and infant (10.6 +/- 7.0%) lungs, but more so in the adult lungs (p < 0.05); these changes were paralleled by histology and pressure-volume characteristics. After high stretch in vivo ventilation, adult but not infant rats developed lung injury (total lung compliance, wet/dry ratio, tumor necrosis factor alpha). Surface video microscopy demonstrated greater heterogeneity of alveolar distension in ex vivo adult versus infant lungs. CONCLUSION: These data provide ex vivo and in vivo evidence that comparable ventilator settings are significantly more injurious in the adult than infant rat lung, probably reflecting differences in intrinsic susceptibility or inflation pattern.

Drug evaluation: E-5564.

Eisai Co Ltd is developing the injectable endotoxin antagonist E-5564, for the potential prevention of the pathophysiological effects of endotoxin-mediated responses caused by bacterial infection, including septic shock.

Pentastarch in a balanced solution reduces hepatic leukocyte recruitment in early sepsis.

OBJECTIVE: To characterize the hepatic leukocyte endothelial cell interactions occurring in early sepsis and to determine whether this is influenced by fluid treatment. METHODS: Sepsis was induced by cecal ligation and perforation in C57Bl/6 mice. One of 6 iv fluid regimes was given immediately postsurgery and at 6 h. The hepatic microcirculation was examined by intravital microscopy at 6 h. RESULTS: All 0.9% saline-based solutions were associated with an increase in leukocyte-endothelial cell interactions as demonstrated by an increase in the rolling flux in the sham and naïve mice. In the septic mice treated with normal saline, there was a 20-fold increase in leukocyte adhesion within the postsinusoidal venules, compared to sham mice. Treatment with lactated Ringer's reduced the sepsis-mediated leukocyte recruitment by 50%. When septic mice received 6% pentastarch in a balanced solution or 3% saline, venular leukocyte adhesion was reduced by an additional 50%. When the pentastarch was prepared in normal saline there was no further reduction in venular leukocyte adhesion compared to the lactated Ringer's-treated mice. All hyperosmolar solutions improved the sepsis-induced reduction in sinusoidal perfusion but only the pentastarch in the balance solution significantly reduced the number of adherent leukocytes within the sinusoids. CONCLUSIONS: Hepatic leukocyte recruitment occurs early in sepsis. Pentastarch in a balanced solution but not in normal saline significantly reduces hepatic leukocyte recruitment, suggesting solution composition, as well as osmolarity impact the innate immune response.

Tifacogin (Chiron Corp/Pharmacia Corp).

Tifacogin is a recombinant tissue factor pathway inhibitor (rTFPI) under development by Pharmacia Corp (formerly GD Searle) and Chiron as a potential treatment for sepsis. The product is in phase III trials [406208]. In July 2000, Pharmacia anticipated regulatory filings in 2002 [374505]. Chiron and Searle conducted research on TFPI independently in the early 1990s and entered an agreement to collaborate on the development, manufacturing and marketing of the compound in 1994, granting each other licenses on the patents concerned with TFPI [224098]. Searle (Monsanto Co) first disclosed recombinant TFPI in the associated patent, US-05212091. Unlike natural TFPI, however, it possessed an N-terminal alanine and the expression method using E coli did not always yield entirely homologous protein. A method for expressing genuine TFPI in yeast is disclosed in Chiron's patent WO-09604377. Patents for methods of treating sepsis with TFPI were claimed independently in two patents from Cetus Oncology (Chiron; WO-09324143) and Searle (WO-09325230). The discovery research of TFPI was conducted by Searle in collaboration with Washington University [224098]. Washington University holds two patents, EP-00563023 and WO-09604378, which claim the use of TFPI for the inhibition of microvascular thrombosis and reperfusion injury, respectively. Analysts at Lehman Brothers predicted in December 2001, that there was a 50% probability of the drug making it to market, with peak sales potential of 500 million US dollars in 2003 [434768].