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Effect of bifidobacterium on defensin-5 expression in intestinal injury of preweaning rats
Wei Wang1, Shu-Fen Yang1, Li-Hong Ren1
1Wei 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.
Insights
Bifidobacterium administration reduced myeloperoxidase (MPO) activity in preweaning rats with endotoxin-induced intestinal injury. This probiotic intervention protected the gut by inhibiting MPO, not by altering defensin-5 mRNA levels.
Area of Science:
- Gastroenterology
- Microbiology
- Pediatric Research
Background:
- Intestinal injury in preweaning animals can be induced by endotoxins like lipopolysaccharide (LPS).
- Myeloperoxidase (MPO) and defensin-5 are key markers in intestinal inflammation and defense.
Purpose of the Study:
- To investigate the protective effects of Bifidobacterium on endotoxin-induced intestinal injury in preweaning rats.
- To assess the impact of Bifidobacterium on MPO activity and defensin-5 mRNA expression.
Main Methods:
- Preweaning rats were divided into control, LPS-induced injury (model), and Bifidobacterium-treated groups.
- Bifidobacterium was administered intragastrically before LPS injection.
- Serum and ileal MPO levels and ileal defensin-5 mRNA expression were measured at various time points post-LPS.
Main Results:
- LPS injection significantly increased serum and ileal MPO levels and ileal defensin-5 mRNA expression compared to controls.
- Bifidobacterium treatment significantly reduced MPO levels in both serum and ileum compared to the LPS-induced group.
- While Bifidobacterium treatment lowered defensin-5 mRNA expression compared to the LPS group, it remained higher than in controls at 2 hours.
Conclusions:
- Endotoxin-induced intestinal injury in preweaning rats is associated with increased MPO activity and defensin-5 mRNA expression.
- Bifidobacterium demonstrates a protective effect against endotoxin-induced intestinal injury.
- The protective mechanism of Bifidobacterium involves the inhibition of MPO activity, independent of significant modulation of defensin-5 secretion.
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 × 10(9) 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.
