| Endometritis is a common obstetric disease in dairy cattle breeding,causing huge economic losses in the dairy industry.There are various pathogens causing endometritis,and there are geographical differences in pathogens,which brings difficulties to the selection of antibiotics;in the case of unclear strains,the abuse of broad-spectrum antibiotics predisposes bacteria to drug resistance and also poses to a serious threat to human life.Research on the use of non-anti-drugs for the treatment of endometritis has received increasing attention.Mannanoligosaccharides(MOS)are known as potential alternatives to antibiotic growth promoters and can enhance the body’s immunity.As an immunopotentiator,MOS is increasingly used in the rearing of pigs and poultry,but its effect on inflammation is not clear,and it is also relatively less used in dairy cattle rearing.In this study,we first conducted an epidemiological survey of cow endometritis in five large-scale dairy farms in Tongliao,Inner Mongolia,to find out the infection of cow endometritis in this area,and treated the cow endometrial epithelial cell line(BEND)with lipopolysaccharide(LPS)to establish a cow endometrial inflammatory cell model,and to explore the effect of MOS in the treatment of cow endometrial inflammatory cell model and the effect on inflammatory factor secretion and apoptosis,in order to accumulate data for the study of MOS on inflammatory factor secretion and apoptosis,and to have certain guiding significance for the use of MOS during dairy cattle breeding and the prevention and treatment of cow endometrial inflammation in actual production.The content and results of this study are as follows:1.The incidence of cow endometritis in some areas of Inner Mongolia was investigated,and the incidence of cow endometritis was statistically analyzed according to different months,parity,and milk yield,with a total of 22,398 cows investigated,of which 3,721 cows were found to have cow endometritis.The average incidence of cow endometritis in this area was 16.61% from October 2019 to October 2021,and the prevalence of the disease was seasonal,with frequent occurrence in summer and winter;the incidence of cow endometritis was positively correlated with milk yield and negatively correlated with parity.2.BEND cells were treated with different concentrations of LPS(0 μg/m L,0.25μg/m L,0.5 μg/m L,1 μg/m L,and 2 μg/m L)for 3,6,9,12,and 24 h.The results showed that the cell viability of cells treated with LPS for 3,9,12,and 24 h was significantly or extremely significantly decreased compared with the control group(P < 0.05,P <0.01),but the cell viability of cells treated with different concentrations of LPS for 6 h was significantly or extremely significantly increased compared with the control group(P < 0.05,P < 0.01).All cell samples were collected to detect the expression of inflammatory factors and changes in apoptotic signaling pathways in the cow endometritis cell model using RT-q PCR experimental methods,and the results showed that IL-1β,IL-6 and IL-8 m RNA expression levels were significantly or extremely significantly higher than those in the control group(P < 0.05,P < 0.01);however,IL-18 m RNA expression levels were not affected by LPS;Caspase 3,Caspase 4,Caspase7 and Caspase8 m RNA levels were significantly or extremely significantly higher than those in the control group(P < 0.05,P < 0.01),but the m RNA expression levels of Caspase9 and Caspase11 were not affected by LPS.The expression levels of inflammatory factor-related genes showed dynamic changes with different time of LPS treatment of cells,and endometrial epithelial cells had some tolerance to LPS.Western blot results showed that the p-P65/p65 ratio was significantly increased in the control group treated with LPS at 2 μg/m L for 12 h(P < 0.05);the p-P65/p65 ratio was significantly increased in the control group treated with LPS at 0.5 μg/m L,1 μg/m L,and 2 μg/m L for 6 h(P < 0.05);BEND cells treated with different concentrations of LPS for 6 h showed that the Caspase3 protein expression was significantly increased in the control group treated with LPS 2 μg/m L(P < 0.05).3.Coli and S.aureus were separately inoculated onto beef extract peptone medium containing different concentrations of MOS,and it was found that the medium containing 0.048 g/m L and 0.06 g/m L of MOS completely inhibited both bacteria,respectively.BEND cells were treated with different concentrations of MOS(0 mg/m L,0.125 mg/m L,0.25 mg/m L,0.5 mg/m L,and 1 mg/m L)for 3 h,6 h,12 h,and 24 h.The results revealed that MOS highly significantly reduced the viability of the cells compared with the control group(P < 0.01);however,after co-treatment of cells with different doses of MOS and LPS for 12 h and 24 h,the cell viability was not different from the control group,but significantly higher than that of the LPS group(P < 0.05);compared with the LPS-treated group,MOS for 6 h significantly reduced the m RNA expression levels of cytokine-related genes IL-1β,IL-6,and IL-8,apoptosis-related genes caspase 3 and Caspase 4,and cholesterol metabolism-related genes CH25 H and insulin-induced gene 2(INSIG2)(P < 0.05);HMGCR,cholesterol regulatory elementbinding proteins(SREBP2)and insulin-inducible gene 1(INSIG1)m RNA expression were significantly increased compared with the LPS group(P < 0.05).In summary,the results of this study showed that MOS had antibacterial ability against the main pathogenic bacteria of cow endometritis,and treatment with MOS on the basis of endometritis cell model could alleviate LPS-induced decrease in cell viability,increased expression of inflammatory and apoptosis-related factors and LPSinduced decrease in cholesterol synthesis.MOS may inhibit the release of inflammatory factors in a cell model of endometritis through the CH25H-NF-κB pathway.This provides a theoretical basis for the clinical use of MOS in the treatment of cow endometritis. |
