Activation of neutrophil function by recombinant human granulocyte colony-stimulating factor improves the survival of rats with peritonitis

Differential effects of antibiotics in combination with G-CSF on survival and polymorphonuclear granulocyte cell functions in septic rats

BACKGROUND

In addition to their antimicrobial activity, antibiotics modulate cellular host defence. Granulocyte-colony stimulating factor (G-CSF) is also a well known immunomodulator; however little is known about the interactions of G-CSF with antibiotics. We investigated in septic rats the effects of two antibiotic combinations with G-CSF.

METHODS

In two clinic modelling randomised trials (CMRTs), male Wistar rats were anesthetized, given antibiotic prophylaxis, had a laparotomy with peritoneal contamination and infection (PCI), and were randomly assigned (n = 18 rats/group) to: 1) PCI only; 2) PCI+antibiotic; and, 3) PCI+antibiotic+G-CSF prophylaxis (20 mug/kg, three times). This sequence was conducted first with 10 mg/kg coamoxiclav, and then with ceftriaxone/metronidazole (Cef/met, 10/3 mg/kg). In additional animals, the blood cell count, migration and superoxide production of PMNs, systemic TNF-alpha and liver cytokine mRNA expression levels were determined.

RESULTS

Only the combination coamoxiclav plus G-CSF improved the survival rate (82 vs. 44%, p < 0.001). Improved survival with this combination was accompanied by normalised antimicrobial PMN migratory activity and superoxide production, along with normalised systemic TNF-alpha levels and a reduced expression of TNF-alpha and IL-1 in the liver.

CONCLUSION

There are substantial differences in the interaction of antibiotics with G-CSF. Therefore, the selection of the antibiotic for combination with G-CSF in sepsis treatment should be guided not only by the bacteria to be eliminated, but also by the effects on antimicrobial functions of PMNs and the cytokine response.

Effects of granulocyte-colony stimulating factor on the polymorphonuclear leukocyte activity and the course of sepsis in rats with experimental peritonitis

PURPOSE

Polymorphonuclear leucocytes (PML) play an essential role in the host immune response to severe infections. The effects of granulocyte-colony stimulating factor (G-CSF) on the PML immune functions during serious abdominal infection and course of sepsis, and on the survival in rats with peritonitis are the main subjects of this study.

METHODS

The first phase of the study was carried out on 30 Wistar-albino rats equally divided into three groups; Group 1 (control) sham laparotomy; Group 2 (peritonitis); and Group 3 (peritonitis+G-CSF) with fecal peritonitis created by a cecal puncture. At postoperative hours 3, 12, and 24, 0.5 ml normal saline was injected subcutaneously in groups 1 and 2, and 0.5 ml solution containing 50 microg/kg of G-CSF in group 3. The phagocytic and chemotactic activities of neutrophils and monocytes were evaluated by a flow cytometry analysis. The plasma lactate concentrations were assessed as a marker of tissue perfusion during sepsis. The second phase was a survival analysis, which was observed during 10 days on 20 rats equally divided into two groups; group 1 (peritonitis) and group 2 (peritonitis+G-CSF). 0.5 ml normal saline in group 1 and 50 microg/kg of G-CSF in group 2 was injected subcutaneously at the 3rd hour and twice daily.

RESULTS

Both the neutrophil- (1.636 vs 2.236) and monocyte-related (1.789 vs 2.465) phagocytic activities significantly (P < 0.001) improved after the G-CSF administration in the rats with peritonitis. In addition, the G-CSF treatment significantly (P < 0.0014) improved the chemotactic activity (1.18 vs 2.75) of neutrophils, and partly supported (P < 0.0952) the chemotactic activity (1.69 vs 2.37) of monocytes. The plasma lactate level (1.86 vs 4.9 mmol/l) was significantly (P < 0.0001) increased after septic changes due to experimental peritonitis. On the other hand, the lactate concentration was significantly (P < 0.001) decreased (4.9 vs 2.63 mmol/l) after the G-CSF administration. The survival was 20% at the 4th day and 0 at the 6th day in peritonitis, and 90% at the 4th day (P = 0.0055) and 80% at the 6th day (P = 0.0007) days in the peritonitis+G-CSF groups.

CONCLUSION

G-CSF enhances the immune functions of neutrophils and monocytes. The increased activities of these cells have a beneficial effect on the enhancement of the host immune response during severe infections. The improved immune function of PML due to the G-CSF treatment thus ameliorates the survival and the courses of sepsis, which is also defined by tissue perfusion and the cellular oxygen balance, which is affected by septic changes.

Dependence of Positive Effects of Granulocyte Colony-stimulating Factor on the Antibiotic Regimen: Evaluation in Rats with Polymicrobial Peritonitis

We tested the hypothesis that the ability of granulocyte colony-stimulating factor (G-CSF) to prevent death from fecal peritonitis is influenced by the composition of the antibiotic regimen with which it is administered. We used a rodent model of polymicrobial peritoneal contamination and infection and the concept of clinical modeling randomized trials (CMRTs), which includes the conditions of randomized, clinical trials and complex clinical interventions (e.g., anesthesia, volume substitution, antibiotics, surgery, postoperative analgesia). With the peritonitis model we obtained a mortality dose-response curve that was sensitive to antibiotic prophylaxis. G-CSF was most efficacious when it was administered both prophylactically and after the onset of peritonitis. Cefuroxime/metronidazole, ofloxacin/metronidazole, and amoxicillin/clavulanate improved survival in combination with G-CSF best, whereas cefotaxime or ceftriaxone with and without metronidazole did not. G-CSF administration was associated with improved polymorphonuclear neutrophil phagocytosis and enhanced bacterial clearance. Pro-inflammatory cytokine release (tumor necrosis factor-a, interleukin-6, macrophage inflammatory protein-2) was decreased in plasma and in the peritoneal fluid. Their expression was lowered in various organs on the protein and mRNA level. The results were used to design a clinical trial to test the ability of G-CSF to prevent serious infections in patients with colorectal cancer surgery. In this trial G-CSF application and antibiotic prophylaxis were performed with the most effective scheduling and combinations (cefuroxime/metronidazole and ofloxacin/metronidazole) as defined here.

Granulocyte colony-stimulating factor but not peritoneal lavage increases survival rate after experimental abdominal contamination and infection

BACKGROUND

The value of peritoneal lavage for intra-abdominal contamination and infection has never been proven scientifically. In contrast, the stimulation of host defence mechanisms with cytokines such as granulocyte colony-stimulating factor (G-CSF) has appeared promising in recent clinical trials.

METHODS

Clinic modelling randomized trials (CMRTs), which model the complexity of the clinical reality, were used in rats in which peritoneal contamination and infection (PCI) was produced with human stool bacteria. The following groups were compared: trial 1, intraoperative peritoneal lavage with saline versus taurolin (18 rats per group); trial 2, no lavage versus saline lavage versus saline lavage plus subcutaneous administration of G-CSF (18 rats per group); trial 3, lavage with saline versus no lavage (30 rats per group). The primary endpoint was mortality at 120 h. Secondary endpoints were the phagocytic activity of granulocytes, and systemic and peritoneal cytokine levels.

RESULTS

In trial 1 lavage with taurolin was not superior to that with saline (five of 18 versus eight of 18 animals survived; P = 0.32). In trial 2, six of 18 animals having no lavage and three of 18 receiving saline lavage survived. The combination of lavage and G-CSF increased the number of animals surviving to 11 of 18 (P < 0.05). Lavage combined with G-CSF stimulated granulocyte phagocytic activity (P < 0.01) and reduced the levels of interleukin (IL) 6 (P < 0.01) and tumour necrosis factor alpha (P < 0.05) in peritoneal fluid, as well as plasma levels of IL-6 (P < 0.05) and IL-10 (P < 0.01). In trial 3, survival was not significantly different in animals having lavage (14 of 30) and no lavage (19 of 30) (P = 0.14).

CONCLUSION

In these CMRTs of intra-abdominal contamination and infection, peritoneal lavage was not beneficial, but when lavage was combined with subcutaneous administration of G-CSF mortality was reduced and the local and systemic cytokine response was downgraded. Results from these CMRTs were used directly to define the trial conditions of a randomized clinical trial with G-CSF. Peritoneal lavage is not recommended.