The Effect Of Endogenous Glucocorticoid On Trauma Induced Myeloid Derived Suppressor Cells (TIMDSCs)

Background:Stress-does of glucocorticoid has been demonstrated to be beneficial for trauma patients in clinical studies. Recently, myeloid derived suppressor cells (MDSCs) have been found to accumulate in trauma host and can be induced by glucocorticoid in vitro. However, the effect of endogenous glucocorticoid on MDSCs under trauma condition is unknown and is our interest in this study.Methods:After anesthesia, BALB/c mice treated or untreated with RU486 (mifepristone) were subjected to laparotomy to mimic traumatic condition. The percentage of CD11b+/Gr-1+ MDSCs in spleen, peripheral blood and bone marrow was determined by flow cytometry or immunohistochemistry. Arginase-1 protein expression was was measured by Western blot. Wright-Giemsa Stain was used to analyze the morphology of MDSCs which was isolated by magnetic microbeads.Results:RU486 not only blunt MDSCs expansion induced by trauma in spleen, peripheral blood and bone marrow especially at 6h after traumatic stress but also resulted in decreased survival rate of 20% traumatic mice within 7 days. Moreover, neither MDSCs producing arginase-1 or the morphological characterization of trauma induced MDSCs was affected by the blockage of glucocorticoid receptor.Conclusion:Endogenous glucocorticoid may promote MDSCs expansion in a murine trauma model and MDSCs may be beneficial for trauma host.