Basic Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Mar 7, 2015; 21(9): 2638-2644
Published online Mar 7, 2015. doi: 10.3748/wjg.v21.i9.2638
Effect of bifidobacterium on defensin-5 expression in intestinal injury of preweaning rats
Wei Wang, Shu-Fen Yang, Li-Hong Ren, Xiu-Xiu Zhang, Shui-Lian Yu
Wei Wang, Shu-Fen Yang, Li-Hong Ren, Xiu-Xiu Zhang, Shui-Lian Yu, Department of Pediatrics, the Second Affiliated Hospital of Harbin Medical University, Harbin 150086, Heilongjiang Province, China
Author contributions: Wang W designed and performed the research, analyzed the data and wrote the paper; Yang SF designed and performed the research; Ren LH designed the research and analyzed the data; Zhang XX and Yu SL contributed new reagents or analytic tools.
Supported by Foundation of Education Department of Heilongjiang Province, No. 11521124.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Wei Wang, MD, Department of Pediatrics, the Second Affiliated Hospital of Harbin Medical University, No. 246 Xuefu Road, Nangang District, Harbin 150086, Heilongjiang Province, China. wendywang_1972@126.com
Telephone: +86-451-86605665 Fax: +86-451-86605665
Received: September 21, 2014
Peer-review started: September 21, 2014
First decision: October 14, 2014
Revised: October 29, 2014
Accepted: December 5, 2014
Article in press: December 8, 2014
Published online: March 7, 2015
Abstract

AIM: To investigate the protective effect of bifidobacterium in endotoxin-induced intestinal injury in preweaning rats.

METHODS: Preweaning rats were randomly divided into three groups (n = 40 for each): a control group (group C), a model group (group E) and a treatment group (group T). Both groups E and T were intraperitoneally injected with lipopolysaccharide (LPS) at a dose of 5 mg/kg (5 mg/L in normal saline), and group T was intragastrically administrated with bifidobacterium suspension (2.0 × 109 CFU/mL, 0.5 mL each time, twice a day, until the end of the experiment) 7 d before LPS administration. Group C was intraperitoneally injected with normal saline. After intraperitoneal injection and intragastric administration, the rats were placed back to the initial cage to receive breast feeding. The rats were killed at 2, 6, 12, 24 or 72 h, respectively, after endotoxin or physiological saline injection to collect serum and ileal tissue samples. Myeloperoxidase (MPO) contents in serum and ileum were detected at different times, and expression of ileal defensin-5 mRNA was evaluated by reverse transcription-polymerase chain reaction.

RESULTS: Serum and ileal MPO contents in group E were significantly higher than those in group C (serum contents: 107.50 ± 17.70 vs 157.14 ± 24.67, P < 0.05; ileal contents: 1.03 ± 0.21 vs 1.57 ± 0.33, P < 0.05), which peaked at 12 h and 6 h, respectively. MPO contents in group T were significantly lower than those in group E (serum contents: 114.38 ± 24.56 vs 145.25 ± 23.62, P < 0.05; ileal contents: 1.25 ± 0.24 vs 1.57 ± 0.33, P < 0.05). The expression of defensin-5 mRNA in group E was significantly higher than that in group C (0.953 ± 0.238 vs 0.631 ± 0.146, P < 0.05), which peaked at 2 h, and then decreased gradually. The expression of defensin-5 mRNA in group T was significantly lower than that in group E (0.487 ± 0.149 vs 0.758 ± 0.160, P < 0.05) apparently in 24 h. The expression of defensin-5 mRNA at 2 h in group T was significantly higher than that in group C (0.824 ± 0.158 vs 0.631 ± 0.146, P < 0.05).

CONCLUSION: MPO and defensin-5 mRNA increase in preweaning rats with LPS-induced intestinal injury. Bifidobacterium protects the gut by inhibiting MPO activity, not by increasing defensin-5 secretion.

Keywords: Bifidobacterium, Lipopolysaccharide, Ileum, Myeloperoxidase, Defensin-5

Core tip: This study investigated the serum and ileal contents of myeloperoxidase (MPO) and the expression of ileal Defensin-5 mRNA in the preweaning rats with lipopolysaccharide (LPS)-induced intestinal injury. Serum and ileal MPO contents in the model group (group E) were significantly higher than those in the control group (group C) (P < 0.05), which peaked at 12 h and 6 h, respectively. MPO contents in the treatment group (group T) were significantly lower than those in group E (P < 0.05). The expression of defensin-5 mRNA in group E was significantly up-regulated, peaked at 2 h, and then decreased gradually. The expression of defensin-5 mRNA in group T was significantly lower than that in group E (P < 0.05). Serum and ileal MPO contents and ileal expression of defensin-5 mRNA increased in preweaning rats with LPS-induced intestinal injury. Bifidobacterium protects the gut by inhibiting MPO activity, not by increasing defensin-5 secretion.