Objective: We evaluated the effects of a granulocyte-colony stimulating factor (G-CSF) prophylaxis in two clinically relevant situations, hemorrhage on the day before infection (e.g., trauma) and acute hemorrhage followed subsequently by infection (e.g., operative complication). A two-hit model of hemorrhage and polymicrobial peritoneal contamination and infection (PCI) was used to assess the influence of G-CSF on the outcome, bacterial clearance, and cytokine pattern.
Design: Clinic modeling randomized laboratory trial.
Setting: University laboratory.
Subjects: One hundred thirty-two male rats.
Interventions: In trial 1 we compared a) preoperative PCI only; b) preoperative hemorrhage plus PCI; and c) hemorrhage plus PCI plus G-CSF prophylaxis (n=18 rats/group). In trial 2, intraoperative hemorrhage was assessed with the same trial design. Primary end point was survival at 120 hrs. In trial 2 additionally, six rats per group and six naive control rats were used for secondary end point analysis.
Measurements and main results: Primary end point was mortality at 120 hrs. Secondary end points were granulocyte counts, bacterial clearance, and local cytokine levels. In trial 1 survival rate was 56% after PCI only, 17% after hemorrhage plus PCI, and 61% after hemorrhage plus PCI plus G-CSF (p<.01). In trial 2 survival rate was 33% after PCI only, 17% after hemorrhage plus PCI, and 50% after hemorrhage plus PCI plus G-CSF (p<.05). In trial 2, neutrophil counts were doubled to 66% 1 hr after hemorrhage (p<.05), colony-forming units of microbes in the lung and liver were halved to 166+/-56 and 134+/-28 colony-forming units (p<.05 for liver), and the macrophage inflammatory protein-2 expression in the lung was halved to 0.88+/-0.06 pg of complementary DNA (p<.05) by G-CSF prophylaxis compared with hemorrhage and PCI.
Conclusions: Hemorrhage (first hit) sensitized the host for a second hit of polymicrobial PCI independent of the timing. G-CSF prophylaxis improved survival and clearance of microbes and reduced the proinflammatory chemokine macrophage inflammatory protein-2 in the lung.