C. Cen1, M. Aziz1,2, W. Yang1,2, J. Nicastro1, G. Coppa1, P. Wang1,2 1Hofstra North Shore LIJ School Of Medicine,Department Of Surgery,Manhasset, NY, USA 2The Feinstein Institute For Medical Research,Center For Translational Research,Manhasset, NY, USA
Introduction: Acute kidney injury (AKI) is most commonly caused by severe sepsis in critically ill patients, and it is associated with high morbidity and mortality. The pathophysiology of sepsis-induced AKI includes direct inflammatory injury, endothelial cell dysfunction, and apoptosis. Milk fat globule-epidermal growth factor-factor VIII (MFG-E8) is a secretory glycoprotein with a known role in the enhancement of apoptotic cell clearance and regulation of inflammation. We hypothesize that MFG-E8 can protect the kidneys from injury caused by sepsis.
Methods: Sepsis was induced in 8-week-old male C57BL/6 mice by cecal ligation and puncture (CLP). Recombinant mouse MFG-E8 (rmMFG-E8) or PBS (vehicle) was injected intravenously at a dosage of 20 µg/kg body weight at time of CLP (n=4-5 mice/group). After 20 h, serum and renal tissue were harvested for various analyses. The renal injury markers blood urea nitrogen (BUN) and creatinine were determined by enzymatic and chemical reactions, respectively. The levels of mRNA and protein were measured by real-time qPCR and ELISA, respectively.
Results: At 20 h after CLP, serum levels of BUN and creatinine were both increased in the vehicle group compared to the sham group (BUN: 39.7 ± 6.6 vs. 17.3 ± 1.7 mg/dL; creatinine: 1.5 ± 0.49 vs. 0.29 ± 0.03 mg/dL; p<0.05). In contrast, animals treated with rmMFG-E8 had a reduction in BUN and creatinine by 31% and 57%, respectively. Levels of mRNA and protein of pro-inflammatory cytokine IL-6 were reduced by 22% and 24%, respectively, in rmMFG-E8-treated mice compared to vehicle mice. The mRNA levels of pro-inflammatory cytokine TNF-α were also reduced by 48% in rmMFG-E8-treated mice compared to the vehicle. The mRNA levels of macrophage inflammatory protein-2 (MIP-2), a chemokine, were reduced by 47% in mice treated with rmMFG-E8 compared to the vehicle group. In addition, the expression of platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31) mRNA was downregulated by 27% in rmMFG-E8-treated mice compared to the vehicle animals (p<0.05).
Conclusion: Treatment with rmMFG-E8 reduces renal tissue injury induced by sepsis through inhibiting the production of pro-inflammatory cytokines and chemokines, as well as through decreasing the activation of endothelial cells. Thus, MFG-E8 may have a therapeutic potential for treating AKI induced by severe sepsis.