Activated protein C reduces intestinal injury in an experimental model of necrotizing enterocolitis

Background

Necrotizing enterocolitis is a devastating intestinal disease of premature infants. Although activated protein C (APC) is well defined as a physiologic anticoagulant, emerging data suggest that it also has cytoprotective, antiinflammatory, and antiapoptotic properties. There is no study on active protein C administration for necrotizing enterocolitis in animal models.

Methods

Twenty-one Wistar albino rat pups were divided into 3 groups: group 1 = control; group 2 = hypoxia-reoxygenation and saline; group 3 = hypoxia-reoxygenation and APC (0.2 mg/kg per day) treatment. On the 15th day, hypoxia was induced by placing the pups in a 100% carbon dioxide chamber for 5 minutes. After the hypoxia period, the pups were reoxygenated for 10 minutes with 100% oxygen and returned to their mothers. All pups were killed 4 hours after the hypoxia-reoxygenation period was over. The abdomen was opened, and representative samples of injured areas were taken for histopathologic examination, nitrite levels, apoptosis, and cytokine levels.

Results

On histopathologic examination, injury scores in group 2 animals were found to be significantly higher than in group 3 animals (P = .002). Significantly increased intestinal nitric oxide levels were found in group 2 rats compared with the rats of groups 1 and 3 (P = .001 and P = .001, respectively). The APC treatment was significantly reduced “apoptotic cell death” in the bowel, when compared with vehicle-treated group. The proinflammatory cytokine levels (interleukin IL]-1β, tumor necrosis factor TNF]-α, and IL-6) were significantly increased in hypoxia group as compared with control group. The concentration of cytokines, IL-1β, IL-6, and TNF-α was reduced in the APC treatment group.

Conclusion

The APC treatment attenuates hypoxia-reoxygenation induced with intestinal injury and decreased apoptotic cell index in this animal model. The protective effect of APC is associated with its ability to reduce the expression of inflammatory cytokines and nitric oxide.