Protective Effect And Mechanism Of Trichosanthes Kirilowii Water Extract On Staphylococcus Aureus Mastitis In Mice

Cow mastitis is a disease caused by a variety of pathogenic factors acting on the mammary gland tissues of cows.The common pathogenic factors include pathogenic microorganism infection,chemical stimulation,physical damage and improper feeding management.Dairy cow mastitis will lead to a significant decline in milk production and milk quality,which will bring huge economic losses to the development of animal husbandry.Staphylococcus aureus(S.aureus)is an important pathogen that causes mastitis in dairy cows.S.aureus can repeatedly infect breast tissue,induce breast inflammation and apoptosis,and the released exotoxin can cause systemic symptoms,leading to cow death.Therefore,the prevention and treatment of S.aureus mastitis should consider anti-inflammatory and enhance the bactericidal effect of the immune system.Trichosanthes kirilowii(T.kirilowii)burdock soup is a classic prescription used clinically in the treatment of mastitis,and its main ingredient is burdock,in recent years,there have also been studies showing that certain internal components of T.kirilowii seeds,T.kirilowii fruit peel,T.kirilowii fruit etc.have good antibacterial and anti-inflammatory effects.However,the prevention and treatment of mastitis by T�kirilowii has not been reported so far.Based on it,this experiment uses mice induced by S.aureus as an experimental animal model to explore the preventive effect and molecular mechanism of the extract of T.kirilowii on mastitis,so as to provide a theoretical basis for clinical screening of drugs that effectively prevent mastitis in cows.First,the 7-day-old lactating female mice were randomLy divided into blank control,S.aureus,S.aureus+T.kirilowii extract(0.25 g/mL,0.5 g/mL,1 g/mL)and S.aureus+dexamethasone(DEX)group.Lactose mice were given 0.25 g/mL,0.5g/mL,and 1 g/mL T.kirilowii extract for 7 days,and then the mammary glands of the mice were infected with 20?L S.aureus(2�10~8 CFU/mL)to inflammation animal model.DEX mice were injected intraperitoneally with DEX 1 hour before S.aureus breast catheter perfusion.After 24 hours of S.aureus breast catheter perfusion in the above groups,the mice were sacrificed by cervical dislocation.The skin of the mice was dissected along the midline of the abdomen and the breast tissue samples were collected.By detecting the pathological changes of the breast tissue,inflammation the expression of sex cytokines IL-1?and TNF-?and the activity of MPO were used to evaluate the protective effect of burdock extract on mice mastitis induced by S.aureus.The results showed that compared with the blank control group,the mammary acinar wall of the S.aureus group was significantly thickened and had a large amount of inflammatory cell infiltration,the activity is significantly increased.However,the extract of T.kirilowii dose-dependently inhibited the pathological damage of breast tissue,the production of inflammatory cytokines and the increase of MPO activity caused by S.aureus infection.These results indicate that the extract of T.kirilowii has a protective effect on the inflammation of the mammary glands induced by S.aureus.Mammary epithelial cells are the main functional cells of mammary gland tissues.To further confirm the protective mechanism of the extract of T.kirilowii on S.aureus mastitis,we isolated mouse mammary epithelial cells by dividing the concentration to0.25 mg/mL,0.5 mg/mL and 1 mg/mL were pretreated for 1 h,and then added 1�10~7CFU/mL of S.aureus to stimulate for 4 h,and had a signal on cell activity,inflammatory cytokines and TLR2/NF-?B pathway activity is tested.The results showed that the extract of T.kirilowii inhibited the expression of inflammatory cytokines TNF-?and IL-1?caused by S.aureus,as well as the phosphorylation of the major proteins p65 and I?B in TLR2/NF-?B signaling pathways.These results indicate that the extracts of T.kirilowii inhibited the activation of the TLR2/NF-?B signaling pathway caused by S.aureus infection,thereby inhibiting the expression of its downstream inflammatory cytokines,thereby reducing the inflammatory damage of breast tissue.In summary,this experiment demonstrated that the extract of S.aureus induces mastitis in mice to prove that the extract of T.kirilowii has a protective effect on the inflammatory damage of the mammary gland tissue of mice,and then isolates the mammary gland epithelial cells of mice to study T.kirilowii protective mechanism of the extract on mammary epithelial cells of mice infected with S.aureus.The results showed that the extract of T.kirilowii inhibited the activation of TLR2/NF-?B signaling pathway,reduced the expression of inflammatory cytokines,and then protected the mammary gland inflammation caused by S.aureus infection.The above-mentioned research results indicate that the extract of T.kirilowii can become the development direction of new anti-inflammatory preparations in the future.