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Role of autophagy and its molecular mechanisms in mice intestinal tract after severe burn

Zhang, Duan Y. MS; Qiu, Wei MS; Jin, PeiS MD; Wang, Peng MS; Sun, Yong MD

Journal of Trauma and Acute Care Surgery: October 2017 - Volume 83 - Issue 4 - p 716–724
doi: 10.1097/TA.0000000000001624
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BACKGROUND Severe burn can lead to hypoxia/ischemia of intestinal mucosa. Autophagy is the process of intracellular degradation, which is essential for cell survival under stresses, such as hypoxia/ischemia and nutrient deprivation. The present study was designed to investigate whether there were changes in intestinal autophagy after severe burn in mice and further to explore the effect and molecular mechanisms of autophagy on intestinal injury.

METHODS This study includes three experiments. Kunming species mice were subjected to 30% total body surface area third-degree burn. First, we determined protein of LC3 (light chain 3), beclin-1, and cleaved-caspase3 by Western blotting and immunohistochemical (paraffin) staining to investigate whether there were changes in intestinal autophagy after severe burn in mice. Then, changes of the status of enteric damage postburn were measured by observing intestinal mucosa morphology under a magnifier, hematoxylin and eosin staining, enzyme-linked immunosorbent assay, Western blotting under the condition that the intestinal autophagy was respectively activated by rapamycin and inhibited by 3-methyladenine. Finally, protein of the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway, LC3-II and beclin-1 were assayed, and mice were treated with compound C before burn.

RESULTS The protein of LC3 and beclin-1 were observed at 1 hour postburn and increased to peak-point at 24 hours, reaching the normal level at 96 hours. The cleaved caspase-3 expression increased at 1 hour postburn, but the peak point occurred at 12 hours and had dropped to normal level at 72 hours. In addition, rapamycin enhanced intestinal autophagy and alleviated burn-induced gut damage, while 3-methyladenine showed the against behavior. The AMPK/mTOR pathway which was inhibited decreased the expression of phosphorylated AMPK, LC3-II, and beclin-1, increasing the expression of phosphorylated mTOR.

CONCLUSION Intestinal autophagy is activated and response to intestinal apoptosis after serious burn, which alleviated burn-induced intestinal injury. The AMPK/mTOR pathway may involve in the activation of burn-induced autophagy.

LEVEL OF EVIDENCE Therapeutic/care management, levels of evidence are not applicable to some studies, such as in vitro work, animal models, cadaver studies.

From the Department of Burn Surgery (D.Y.Z., W.Q., P.W., Y.S.), Huaihai Hospital affiliated to Xuzhou Medical University; Department of Burn Surgery (D.Y.Z., W.Q., P.W., Y.S.), No. 97 Hospital of PLA; and Department of Plastic Surgery (P.J.), the Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu Province, China.

Submitted: April 11, 2017, Revised: May 26, 2017, Accepted: May 27, 2017.

Address for reprints: Yong Sun, Department of Burn Surgery (D.Y.Z., W.Q., P.W., Y.S.), No. 97 Hospital of PLA, Xuzhou, Jiangsu Province, China; email: sunyong_97@163.com.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text, and links to the digital files are provided in the HTML text of this article on the journal’s Web site (www.jtrauma.com).

© 2017 Lippincott Williams & Wilkins, Inc.