MAPK pathway.

2023-03-06
Journal of animal science and biotechnology 14(1)
- Jinze Li
- Qiuke Li
- Qianhui Wu
- Nan Gao
- Zhihua Wang
- Yang Yang
- Anshan Shan

PubMed: 36872332
DOI: 10.1186/s40104-023-00830-7

Background

Salmonella typhimurium (S.T), as an important foodborne bacterial pathogen, can cause diarrhea and gastroenteritis in humans and animals. Numerous studies have confirmed that exopolysaccharides (EPSs) have various biological functions, but the mechanism through which EPSs improve the immunity of animals against the invasion of pathogenic bacteria is unclear. Here, we explored the protective effect of EPSs of Lactobacillus rhamnosus GG (LGG) on the S.T-infected intestine.

Methods

Mice received adequate food and drinking water for one week before the start of the experiment. After 7 d of prefeeding, 2×10⁸ CFU/mL S.T solution and an equivalent volume of saline (control group) were given orally for 1 d. On the fourth day, the mice were treated with 0.5 mg/mL EPSs, 1.0 mg/mL EPSs, 2.0 mg/mL EPSs, or 2.0 mg/mL penicillin for 7 d. Finally, the body and relative organ weight, histological staining, and the levels of antioxidant enzyme activity and inflammatory cytokines were determined.

Results

The S.T-infected mice exhibited symptoms of decreased appetite, somnolence, diarrhea and flagging spirit. Treatment with EPSs and penicillin improved the weight loss of the mice, and the high dose of EPSs showed the best therapeutic effect. EPSs significantly ameliorated S.T-induced ileal injury in mice. High-dose EPSs were more effective than penicillin for alleviating ileal oxidative damage induced by S.T. The mRNA levels of inflammatory cytokines in the ileum of mice showed that the regulatory effects of EPSs on inflammatory cytokines were better than those of penicillin. EPSs could inhibit the expression and activation of key proteins of the TLR4/NF-κB/MAPK pathway and thereby suppress the level of S.T-induced ileal inflammation.

Conclusions

EPSs attenuate S.T-induced immune responses by inhibiting the expression of key proteins in the TLR4/NF-κB/MAPK signaling pathway. Moreover, EPSs could promote bacterial aggregation into clusters, which may be a potential strategy for reducing the bacterial invasion of intestinal epithelial cells.

Research Insights

Supplement	Health Outcome	Effect Type	Effect Size
Lactobacillus rhamnosus lysate powder	Improved Intestinal Injury	Beneficial	Large
Lactobacillus rhamnosus lysate powder	Improved Weight Loss	Beneficial	Moderate
Lactobacillus rhamnosus lysate powder	Reduced Intestinal Inflammation	Beneficial	Large
Lactobacillus rhamnosus lysate powder	Reduced Oxidative Stress	Beneficial	Moderate
Lactobacillus rhamnosus lysate powder	Reduced Oxidative Stress in Intestinal Epithelial Cells	Beneficial	Moderate
Lactobacillus rhamnosus lysate powder	Reduced Pathogenic Bacterial Invasion	Beneficial	Moderate