Short communication: Effects of moringa extract on adhesion and invasion of Escherichia coli O55 in bovine mammary epithelial cells

摘要

The objective of this study was to evaluate theantibacterial activities of extract derived from moringaleaves. In particular, the effect of moringa extract(Mor) on adhesion and invasion of Escherichia coliO55, Enterococcus faecalis, Staphylococcus simulans,and Serratia liquefaciens was evaluated in bovine mammaryepithelial cells (MAC-T). Broth microdilutionmethod, minimum inhibitory concentration and minimumbactericidal concentration assays, adhesion andinvasion assays, and real-time PCR were performed.The minimum inhibitory concentration and minimumbactericidal concentration of Mor ranged from 12.5 to50 mg/mL on 18 out of 27 tested isolates. Treatmentof E. coli O55 with Mor (100 and 200 μg/mL) inhibitedthe adhesion and invasion on MAC-T cells via downregulationof adhesion factors (i.e., papC, f17c-A, andeaeA). Also, when MAC-T cells were pretreated withMor (200 μg/mL, 12 h) and incubated with E. coliO55, Enterococcus faecalis, Staphylococcus simulans, orSerratia liquefaciens, both E. coli O55 and Enterococcusfaecalis showed a significant decrease in adhesion andinvasion. Staphylococcus simulans exhibited decreasedadhesion and increased invasion. Serratia liquefaciensshowed increased adhesion and decreased invasion.In addition, Mor increased mRNA expression of antioxidantenzymes (e.g., heme oxygenase-1, NAD(P)H:quinone oxidoreductase-1, and thioredoxin reductase1) in MAC-T cells. In conclusion, 12.5 to 50 mg/mL ofMor exhibited antibacterial activity against 18 out of27 tested isolates. Also, pretreatment of 200 μg/mL ofMor to MAC-T cells modulated adhesion and invasionof E. coli O55 and other mastitis-associated pathogens.Furthermore, Mor increased antioxidant capacities inMAC-T cells, but further in vivo studies are needed.