Bactericidal/permeability-increasing protein preserves leukocyte functions after major liver resection

Abstract

Objective: To analyze postoperative leukocyte functions in patients undergoing hemihepatectomy, and to assess the effect of treatment with the endotoxin-neutralizing agent bactericidal/permeability-increasing protein (rBPI21).

Summary background data: Extensive liver resection is associated with a high incidence of infectious complications. Because elimination of pathogenic microorganisms occurs mainly by leukocytes, this increased rate of infections is most likely due to an impaired function of these cells. Endotoxin, translocated from the gut into the systemic circulation as a result of increased gut permeability and reduced hepatic clearance function after major liver resection, may play an important role in the impairment of posthepatectomy leukocyte function.

Methods: To investigate whether hemihepatectomy results in impaired leukocyte functions and to determine the role of endotoxin in this process, leukocyte oxidative burst and leukocyte antigen expression were studied in three groups of patients: patients undergoing a hemihepatectomy and receiving rBPI21 treatment, patients undergoing hemihepatectomy and receiving placebo, and as an extra control group patients undergoing other major abdominal surgeries. Blood samples were collected before surgery, 2 hours after surgery, and at days 1, 2, 5, and 7. Phorbol myristate acetate-stimulated oxidative burst was measured using dihydrorhodamine, and leukocyte surface expression of the antigens CD11b, CD16, and CD14 was investigated by indirect immunofluorescence. Both oxidative burst and membrane surface expression were quantified by flow cytometry. An indication of the antiendotoxin effect of rBPI21 treatment was provided by assessment of plasma lipopolysaccharide binding protein (LBP) levels by enzyme-linked immunosorbent assay.

Results: The oxidative burst in the hemihepatectomized patients receiving placebo and the controls increased 2 hours after surgery, whereas it decreased in the rBPI21-treated patients, resulting in significant differences between the groups. On day 1, neutrophil CD11b expression and monocyte CD14 expression in the rBPI21-treated patients and controls were significantly lower than in the placebo group. At 2 hours, CD16 expression in the placebo-treated patients was significantly higher than in the rBPI21-treated patients and controls. On day 5 and day 7, plasma LBP levels were significantly higher in the placebo-treated patients compared with the rBPI21-treated patients.

Conclusions: The results of this study show that patients undergoing major liver resection have an increased activation of leukocytes compared with those undergoing other major abdominal surgery. This enhanced activation may contribute to the increased risk of infection in these patients. Administration of the endotoxin-neutralizing agent rBPI21 to hemihepatectomy patients was shown to reduce plasma LBP levels, to preserve leukocyte functions partially, and to reduce leukocyte activation to the level of other, nonhepatic abdominal surgery.

Figure 1. Course of the APACHE III scores from the control patients (□), the placebo-treated hemihepatectomy patients (○), and the rBPI₂₁-treated hemihepatectomy patients (•). There were no significant differences among the groups. Data are expressed as means ± standard error of the mean.

Figure 2. Phorbol myristate acetate-stimulated oxidative burst activity as measured by mean channel fluorescence before and during the first week after surgery by the polymorphonuclear leukocytes of control patients (□), placebo-treated hemihepatectomy patients (○), and rBPI₂₁-treated hemihepatectomy patients (•). Significant differences between the groups are indicated by asterisks. Data are expressed as means ± standard error of the mean.

Figure 3. Expression of CD11b (A) and CD16 (B) was measured by mean channel fluorescence before and during the first week after surgery on polymorphonuclear leukocytes in control patients (□), placebo-treated hemihepatectomy patients (○), and rBPI₂₁-treated hemihepatectomy patients (•). Significant differences between the groups are indicated by asterisks. Data are expressed as means ± standard error of the mean.

Figure 4. Perioperative CD14 expression on monocytes of control patients (□), placebo-treated hemihepatectomy patients (○), and rBPI₂₁-treated hemihepatectomy patients (•), measured by mean channel fluorescence. Significant differences between the groups are indicated by asterisks. Data are expressed as means ± standard error of the mean.

Figure 5. Perioperative plasma lipopolysaccharide binding protein levels in placebo-treated hemihepatectomy patients (○) and rBPI₂₁-treated hemihepatectomy patients (•), measured by enzyme-linked immunosorbent assay. Significant differences between the groups are indicated by asterisks. Data are expressed as means ± standard error of the mean.