Coagulation blockade prevents sepsis-induced respiratory and renal failure in baboons.

Sepsis-induced tissue factor (TF) expression activates coagulation in the lung and leads to a procoagulant environment, which results in fibrin deposition and potentiates inflammation. We hypothesized that preventing initiation of coagulation at TF-Factor VIIa (FVIIa) complex would block fibrin deposition and control inflammation in sepsis, thereby limiting acute lung injury (ALI) and other organ damage in baboons. A model of ALI was used in which adult baboons were primed with killed Escherichia coli (1 x 10(9) CFU/kg), and bacteremic sepsis was induced 12 h later by infusion of live E. coli at 1 x 10(10) CFU/kg. Animals in the treatment group were given a competitive inhibitor of TF, site-inactivated FVIIa (FVIIai), intravenously at the time of the infusion of live bacteria and monitored physiologically for another 36 h. FVIIai dramatically protected gas exchange and lung compliance, prevented lung edema and pulmonary hypertension, and preserved renal function relative to vehicle (all p < 0.05). Treatment attenuated sepsis-induced fibrinogen depletion (p < 0.01) and decreased systemic proinflammatory cytokine responses, for example, interleukin 6 (p < 0.01). The protective effects of TF blockade in sepsis-induced ALI were confirmed by using tissue factor pathway inhibitor. The results show that TF-FVIIa complex contributes to organ injury in septic primates in part through selective stimulation of proinflammatory cytokine release and fibrin deposition.

Anti-neutrophil chemokine preserves alveolar development in hyperoxia-exposed newborn rats.

Inflammation may contribute to lung injury and impaired alveolar development in bronchopulmonary dysplasia. We treated hyperoxia-exposed newborn rats with antibodies to the neutrophil chemokine cytokine-induced neutrophil chemoattractant-1 (CINC-1) during 95% O2 exposure to reduce adverse effects of hyperoxia-induced inflammation on lung development. Rats were exposed at birth to air, 95% O2, or 95% O2 + anti-CINC-1 (injected on days 3 and 4). Bromodeoxyuridine (BrdU) was injected 6 h before death. Anti-CINC-1 treatment improved weight gain but not survival at day 8. Anti-CINC-1 reduced bronchoalveolar lavage neutrophils at day 8 to levels equal to air controls. Total detectable lung CINC-1 was reduced to air control levels. Lung compliance was improved by anti-CINC-1, achieving air control levels in the 10-microg anti-CINC-1 group. Anti-CINC-1 preserved proliferating cell nuclear antigen expression in airway epithelium despite 95% O2 exposure. BrdU incorporation was depressed by hyperoxia but preserved by anti-CINC-1 to levels similar to air control. Alveolar volume and surface density were decreased by hyperoxia but preserved by anti-CINC-1 to levels equal to air control. Blockade of neutrophil influx in newborns may avert early lung injury and avoid alveolar developmental arrest that contributes to bronchopulmonary dysplasia.

Proinflammatory cytokines increase in sepsis after anti-adhesion molecule therapy.

Cytokine mediators and leukocyte-endothelial cell adhesion molecules are critical and interdependent components of the acute inflammatory response in sepsis. We hypothesized that the administration of monoclonal antibodies to intercellular adhesion molecule-1 (CD54) or E- and L-selectin (CD62E/L) would decrease serum levels of the proinflammatory cytokines interleukin-1beta (IL-1), IL-6, and IL-8 and tumor necrosis factor receptor (TNFR-1) in baboons during sepsis. Adult male baboons received infusions of 1 x 10(9) colony forming units (CFU)/kg heat-killed Escherichia coli (E. coli) followed 12 h later by live E. coli (1 x 10(10) CFU/kg). At the time of live bacterial infusion, six septic animals were treated with a monoclonal antibody to CD54 and six with an antibody to CD62E and L (1 mg/kg). Eight untreated septic animals served as controls. Sequentially drawn serum samples were assayed for IL-1, IL-6, IL-8, and TNFR-1 using enzyme-linked immunoassay (ELISA). Data were compared using Mann-Whitney U tests and Chi-square analyses. Median survival was decreased in both treatment groups compared to controls (P < 0.05). Peak IL-1 level was higher than controls in septic animals treated with anti-CD54 but not anti-CD62E/L (P < 0.05, P = NS, respectively). Elevations in IL-6, IL-8, and TNFR-1 were increased and prolonged in both antibody treated groups compared to controls (P < 0.05). These results provide the first in vivo evidence that leukocyte-endothelial adhesion molecules CD54 and CD62E/L regulate cytokine production in sepsis.

Changes in the lung after prolonged positive pressure ventilation in normal baboons.

PURPOSE: The effects of prolonged positive pressure ventilation on lung ultrastructure are not well defined in primates. This study was designed to measure cardiopulmonary and morphological responses to 4 days of positive pressure ventilation in normal baboons. MATERIALS AND METHODS: Six adult male baboons were mechanically ventilated on air for 96 hours with 2.5 cm positive end-expiratory ventilation and a tidal volume of 12 to 15 mL/kg. Physiological measurements were obtained every 12 hours and serial measurements of ventilation-perfusion (VA/Q) were performed using the multiple inert gas elimination technique. Quantitative morphotometry, lung dry-to-wet ratio, and surfactant analysis were performed at the end of the experiment. RESULTS: Cardiovascular variables, except for a small increase in mean pulmonary artery pressure at 84 and 96 hours, were not significantly affected by positive pressure ventilation. Arterial Po2 decreased, and shunt fraction increased from 0.7% of cardiac output to 5.4% (P < .01). Dispersion of perfusion increased threefold (P < .01), and dispersion of ventilation doubled (P < .01) indicating increased VA/Q mismatch mismatch. Respiratory system compliance decreased by 30% (P < .01). There was no lung edema or change in surfactant composition. Lung morphometry showed increases in polymorphonuclear cells and type II cell volume. Vacuolated endothelial cells and bare basement membrane were observed consistently. CONCLUSION: Four days of positive pressure ventilation decreases lung compliance and worsens gas exchange by increasing shunt and VA/Q mismatch in healthy baboons. These effects are accompanied by only minor ultrastructural changes and mild inflammatory responses in the lung.

Altered mitochondrial redox responses in gram negative septic shock in primates.

Gram negative sepsis causes changes in oxygen supply-demand relationships. We have used a primate model of hyperdynamic gram negative sepsis produced by intravenous infusion of Escherichia coli (E. coli) to evaluate sepsis-induced alterations in mitochondrial oxidation-reduction (redox) state in muscle in vivo. The redox state of cytochrome a,a3, the terminal member of the intramitochondrial respiratory chain, was assessed in the intact forearm by near-infrared (NIR) spectroscopy. The muscle NIR data were compared to routine measures of oxygen delivery (DO2) and oxygen consumption (VO2). After E. coli infusion and fluid resuscitation, DO2 and VO2 showed minimal changes through 24 hr of sepsis. In contrast, changes in cytochrome a,a3 redox state evaluated by NIR occurred within a few hours and were progressive. Mitochondrial functional responses were correlated with structural changes observed on serial muscle biopsies. Gross morphological changes in muscle mitochondria were present in some animals as early as 12 hr, and, in most animals, by 24 hr. The morphologic changes were consistent with decreases in oxidative capacity as suggested by NIR spectroscopy. The NIR data also suggest that two mechanisms are operating to explain abnormalities in oxygen metabolism and mitochondrial function in lethal sepsis. These mechanisms include an early defect in oxygen provision to mitochondria that is followed by a progressive loss in functional cytochrome a,a3 in the muscle.

Pseudomonas putrefaciens bacteremia.

Pseudomonas putrefaciens is an unusual cause of human disease. Since 1978 only five cases of bacteremia due to this organism have been reported. Within 12 recent months four cases of bacteremia due to P. putrefaciens were seen - two occurred in patients with chronic infections of a lower extremity, one in a patient with neutropenia, and one in a patient with fulminant septicemia and disseminated intravascular coagulation. Two of the patients had prostheses; in neither case did prosthetic infection or prosthetic failure occur. Two syndromes of bacteremic infection with P. putrefaciens are suggested. One syndrome is associated with chronic infection of a lower extremity, is fairly well tolerated, and responds to appropriate antimicrobial agents. The other syndrome is more fulminant and may be associated with severe underlying debility, liver disease, and malignancy. It is not yet known whether this is a meaningful distinction. The significance of the recent increase is the isolation of this organism is not clear at present.