Release of bactericidal/permeability-increasing protein in experimental endotoxemia and clinical sepsis. Role of tumor necrosis factor

Bactericidal/permeability-increasing protein (BP]) is contained within the azurophilic granules of neutrophils and is able to neutralize endotoxin and kill Gram-negative bacteria. TNF has been implicated as a mediator of endotoxin-induced neutrophil degranulation. To assess the role of TNF in the elevated BPI levels during sepsis, the following studies were performed. 1) In 31 consecutive patients with sepsis syndrome, plasma BPI levels were markedly elevated compared with those in healthy controls, but showed no correlation with simultaneously measured TNF concentrations. 2) In four healthy men, i.v. injection of recombinant human TNF (50 microg/m2) induced a rapid rise in plasma BPI levels. 3) In eight normal subjects, i.v. administration of Escherichia coli endotoxin (4 ng/kg) elicited subsequent increases in the plasma concentrations of TNF and BPI. 4) Eight healthy chimpanzees were investigated after i.v. injection of endotoxin (4 ng/kg); four animals received endotoxin only, and four animals received an anti-TNF mAb simultaneously. Although anti-TNF completely prevented the endotoxin-induced appearance of TNF activity, the rise in BPI levels remained unaltered. These results suggest that TNF is not critical for the release of BPI from neutrophils during experimental endotoxemia or clinical sepsis.

Release of bactericidal/permeability-increasing protein in experimental endotoxemia and clinical sepsis. Role of tumor necrosis factor

Bactericidal/permeability-increasing protein (BP]) is contained within the azurophilic granules of neutrophils and is able to neutralize endotoxin and kill Gram-negative bacteria. TNF has been implicated as a mediator of endotoxin-induced neutrophil degranulation. To assess the role of TNF in the elevated BPI levels during sepsis, the following studies were performed. 1) In 31 consecutive patients with sepsis syndrome, plasma BPI levels were markedly elevated compared with those in healthy controls, but showed no correlation with simultaneously measured TNF concentrations. 2) In four healthy men, i.v. injection of recombinant human TNF (50 microg/m2) induced a rapid rise in plasma BPI levels. 3) In eight normal subjects, i.v. administration of Escherichia coli endotoxin (4 ng/kg) elicited subsequent increases in the plasma concentrations of TNF and BPI. 4) Eight healthy chimpanzees were investigated after i.v. injection of endotoxin (4 ng/kg); four animals received endotoxin only, and four animals received an anti-TNF mAb simultaneously. Although anti-TNF completely prevented the endotoxin-induced appearance of TNF activity, the rise in BPI levels remained unaltered. These results suggest that TNF is not critical for the release of BPI from neutrophils during experimental endotoxemia or clinical sepsis.

Inhibition of endotoxin-induced cytokine release and neutrophil activation in humans by use of recombinant bactericidal/permeability-increasing protein

To investigate the effects of a recombinant endotoxin-binding protein, bactericidal/permeability-increasing protein (rBPI23), on cytokine release and neutrophil activation in endotoxemia in humans, 8 volunteers were challenged twice with endotoxin and concurrently received either rBPI23 or placebo in a randomized, placebo controlled, double-blind crossover study, rBPI23 treatment significantly lowered circulating endotoxin levels (P = .02) and resulted in a significant reduction in the release of tumor necrosis factor (TNF), soluble TNF receptors p55 and p75, interleukin (IL)-6, IL-8 (P < .01 for each), and IL-10 levels (P = .02) but did not prevent the endotoxin-induced rise in body temperature. The early endotoxin-induced leukopenia was blunted (P = .08), and neutrophil degranulation, as measured by circulating levels of elastase/alpha 1-antitrypsin complexes (P = .03) and lactoferrin (P < .01), was largely prevented by rBPI23. The results of this study indicate that rBPI23 is capable of neutralizing many of the biologic effects of endotoxin in humans.

Inhibition of endotoxin-induced activation of the coagulation and fibrinolytic pathways using a recombinant endotoxin-binding protein (rBPI23)

A recombinant endotoxin-neutralizing protein, rBPI23, was shown to partially prevent endotoxin-induced activation of the fibrinolytic and coagulation systems in experimental endotoxemia in humans. In a placebo-controlled, blinded crossover study, eight volunteers were challenged twice with an intravenous bolus injection of endotoxin (40 EU/kg of body weight) and concurrently received either rBPI23 (1 mg/kg) or placebo (human serum albumin, 0.2 mg/kg). rBPI23 treatment significantly lowered the endotoxin-induced fibrinolytic response, ie, reduced the release of tissue-type plasminogen activator, urokinase-type plasminogen activator, plasminogen activator inhibitor antigen, and complex formation of plasmin alpha 2-antiplasmin (P = .0078 for each). Plasminogen activator inhibitor activity was also reduced, but not significantly according to the Hochberg method (P = .0304). The endotoxin-induced activation of the procoagulant state as reflected by increase in F1 + 2 fragments and TAT complexes was blunted by rBPI23 infusion (P = .0391 [not significant according to the Hochberg method] and .0078, respectively). These results indicate that rBPI23 is capable of reducing both the activation of the fibrinolytic and the coagulation systems after low-dose endotoxin infusion in humans.

Antithrombin III concentrate in the treatment of DIC: a retrospective follow-up study

OBJECTIVE

To assess the clinical utility of antithrombin III (AT-III) substitution in adults with septicaemia in an intensive care unit.

METHODS

A retrospective follow-up study was performed in the adult intensive care unit of a large teaching hospital. Adults with septicaemia and AT-III levels less than 0.45 IU/ml were identified. AT-III administration, consisting of an intravenous bolus injection of 20 IU/kg, followed by continuous infusion of 20 IU/kg per 24 h, was given to 21 patients, while this was withheld in 21 age- and sex-matched controls. The severity of diffuse intravascular coagulation (DIC), APACHE II score, and type of septicaemia were analysed. The odds ratio was calculated for survival.

RESULTS

The base-line characteristics with regards to severity of DIC, APACHE scores and types of sepsis were comparable for the patients who received AT-III concentrates and those who did not. Mortality in the treated and non-treated groups was 76% (95% CI: 53-92%) and 57% (95% CI: 34-78%), respectively (p = 0.24). The odds ratio for survival was 2.4 if no AT-III concentrate was administered (95% CI: 0.537-11.5; p = 0.24).

CONCLUSIONS

The use of AT-III concentrates in the doses applied in adult intensive care patients with septicaemia does not appear to improve outcome in terms of mortality.

[Immunotherapy using the anti-endotoxin antibody HA-1A in patients with sepsis syndrome; good results in relation to treatment with placebo]

Passive immunization with a human anti-endotoxin monoclonal IgM antibody (Centoxin, HA-1A) was recently studied in patients with suspected Gram-negative sepsis. Comparison of the results obtained in the Amsterdam subpopulation with those in a larger international study population of which the Amsterdam patient group was a part, showed that it had been possible to select a patient population in which HA-1A has an 'intention-to-treat' effect based upon clinical criteria (a decrease in mortality compared with placebo by 42% (p = 0.04) and in the larger study by 9% (p = 0.24). Until a clinically useful test becomes available, identification of patients who have a high likelihood of Gram-negative sepsis and who would benefit from anti-endotoxin immunotherapy with HA-1A should be based upon the history and evaluation of underlying disease, infection status, severity and progression of the disease. The severely ill patients thus selected should receive treatment as early as possible.

Effectiveness of a human monoclonal anti-endotoxin antibody (HA-1A) in gram-negative sepsis: relationship to endotoxin and cytokine levels

Gram-negative sepsis is caused by endotoxin-induced release of tumor necrosis factor (TNF) and other cytokines. HA-1A is a human monoclonal antibody that binds specifically to endotoxin. HA-1A should prevent death in endotoxemic patients and reduce serum levels of TNF and interleukin-6 (IL-6). This hypothesis was tested in 82 septic patients who were randomly allocated to receive a single intravenous 100-mg dose of HA-1A or placebo. Pretreatment endotoxemia was detected in 27 patients (33%). Death occurred within 28 days of treatment in 8 (73%) of 11 placebo recipients and in 5 (31%) of 16 HA-1A recipients (P = .02). The median decrease in serum TNF level 24 h after treatment was 12 ng/L in patients given HA-1A and 0 ng/L in placebo recipients (n = 65; P = .04). For IL-6, this was 204 ng/L in patients given HA-1A and 44 ng/L in placebo recipients (n = 67; P = .4). Thus, HA-1A reduces mortality in septic patients with endotoxemia and lowers serum TNF levels.