Evaluation of Lactiplantibacillus plantarum CRS 33 to therapeutic effects on a murine model of E. coli-induced endometritis

Mingchao Liu^1,2,3Xiangfu Wen³Mingque Feng³Yan Sun³Xiaowei Feng³Tianxiong Jin³Bei Liu³Shahid Muhammad⁴Kangping Liu³Jia Cheng^3*Jianguo Li^1,2*

• ¹College of Animal Science and Technology, Agricultural University of Hebei, Baoding, Hebei Province, China
• ²Key Laboratory of Healthy Breeding in dairy cattle (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs, Hebei Agricultural University, Baoding, China, Baoding, China
• ³College of Veterinary Medicine, Hebei Agricultural University, Bao Ding, China, Baoding, China
• ⁴Center of Microbiology, Veterinary Research Institute, Peshawar, Peshawar, Khyber Pakhtunkhwa, Pakistan

Bovine endometritis, common in postpartum dairy cows, is traditionally treated with antibiotics. However, antibiotic usage is associated with the induction of antimicrobial resistance and treatment failure. Lactiplantibacillus plantarum CRS33 is a newly identified probiotic with strong anti-bacterial activity isolated from a healthy cow uterus in our laboratory. This study sought to explore the probiotic potential of Lactiplantibacillus plantarum CRS33 through whole-genome sequence analysis and evaluate its anti-inflammatory effects on experimentally induced endometritis in mice caused by Escherichia coli (E. coli). A treatment dose of Lactiplantibacillus plantarum CRS33 (1×109 CFU/mL) was selected for endometritis therapy in mice. Whole-genome sequencing results showed that the strain possesses genes associated with antibacterial, anti-inflammatory, and immune-regulating pathways, while no drug resistance or pathogenicity genes were identified. Lactiplantibacillus plantarum CRS33 significantly reduced endometrial inflammation, inhibiting pathological changes and reducing uterus wet weight index (p < 0.05). It also suppressed inflammatory cell infiltration and reduced pro-inflammatory cytokine levels (IL-6, IL-1β, IL-8, TNF-α). Furthermore, Lactiplantibacillus plantarum CRS33 diversifies the microbial community and increases the proportion of dominant flora in the uterus. Although these findings highlight the potential of probiotics in treating bovine endometritis, this study is limited by the use of a mouse model. We will consider further validation in dairy cows.