Relationship between MFG-E8-mediated efferocytosis and sepsis-associated encephalopathy in mice / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the relationship between milk fat globular epidermal growth factor Ⅷ (MFG-E8)-mediated efferocytosis and sepsis-associated encephalopathy (SAE) in mice.Methods:Forty clean-grade healthy male C57BL/6 mice, aged 2-3 months, weighing 18-22 g, were divided into 4 groups ( n=10 each) using a random number table method: sham operation group (group Sham), cecal ligation and perforation (CLP) group (group CLP), sham operation+ phosphate buffer solution (PBS) group (group Sham+ PBS) and CLP+ recombinant mouse MFG-E8 group (group CLP+ rmMFG-E8). SAE was induced by CLP in anesthetized mice.PBS 1 μl and rmMFG-E8 1 μg were injected into the lateral cerebral ventricle in Sham+ PBS and CLP+ rmMFG-E8 groups after operation for 5 consecutive days.Novel object recognition test was performed at 6 days after operation, and the contextual fear conditioning test was performed at 7 and 8 days after operation.The percentage of time spent exploring a novel object, discrimination index and percentage of freezing time induced by condition were calculated.The animals were sacrificed after the end of behavioral tests, and the hippocampus was extracted for determination of the expression of MFG-E8 and GTP-Rac1 (by Western blot), the mRNA expression levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α and IL-1β (using real-time reverse transcription-polymerase chain reaction) and the apoptosis rate in hippocampus (by TUNEL). Results:Compared with group Sham, the percentage of time spent exploring a novel object, discrimination index and percentage of freezing time were significantly decreased, hippocamcal MFG-E8 expression was down-regulated, GTP-Rac1 expression was up-regulated, mRNA expression of IL-6, TNF-α and IL-1β was up-regulated, and apoptosis rate was increased in group CLP ( P<0.05). Compared with group CLP, the percentage of time spent exploring a novel object and discrimination index were significantly increased, freezing time was prolonged, hippocamcal MFG-E8 and GTP-Rac1 expression was up-regulated, mRNA expression of IL-6, TNF-α and IL-1β was down-regulated, and apoptosis rate was decreased in group CLP+ rmMFG-E8 ( P<0.05). Conclusion:The reduction of hippocampal MFG-E8-mediated efferocytosis may be involved in the pathophysiological mechanism of SAE in mice.