Renal ischemia-reperfusion (I/R) injury causes acute renal failure and the hallmarks of renal I/R injury are inflammation, apoptosis, necrosis, and capillary dysfunction. Milk fat globule-EGF factor VIII (MFG-E8), a membrane-associated secretory glycoprotein, is produced by immune cells and reported to participate in multiple physiological processes associated with tissue remodeling. We have recently shown that MFG-E8 treatment attenuates organ injury, inflammatory responses, and survival after sepsis through the enhancement of phagocytosis of apoptotic cells. The purpose of this study was to determine whether administration of MFG-E8 attenuates renal I/R injury.
Prospective, controlled, and randomized animal study.
A research institute laboratory.
Male C57BL/6J mice (20–25g).
Renal I/R injury with bilateral renal pedicle clamping for 45 minutes, followed by reperfusion. A recombinant murine MFG-E8 (rmMFG-E8; 0.4 µg/20g) was given intraperitoneally at the beginning of reperfusion.
Measurements and Main Results
MFG-E8 levels, organ injury variables, inflammatory responses, histology, apoptosis, and capillary functions were assessed at 1.5 and 20 hours after reperfusion. A 60-hour survival study was conducted in MFG-E8−/− and rmMFG-E8-treated wild-type (WT) mice. After renal I/R injury, MFG-E8 mRNA and protein expressions were significantly decreased in the kidneys and spleen. Treatment with rmMFG-E8 recovered renal dysfunction, significantly suppressed inflammatory responses, apoptosis, necrosis, and improved capillary functions in the kidneys. In the survival study, MFG-E8−/− mice showed a significant deterioration and, in contrast, rmMFG-E8-treated WT mice showed a significant improvement of survival compared with vehicle-treated WT mice.
MFG-E8 can be developed as novel treatment for renal I/R injury. This protective effect appears to be mediated through the enhancement of apoptotic cell clearance and improvement of capillary functions in the kidneys.