TLR4 and mastitis: Consistently, several probiotics, such as Lactobacillus plantarum (L. plantarum 17-5) [118,119], Lactobacillus casei [120], Lactobacillus rhamnosus GR-1 [114,121], and Bacillus subtilis [114,122], have been found to prevent inflammatory changes in MMECs and subsequently prevent mastitis caused by E. coli. Furthermore, Bacillus subtilis was found to prevent inflammatory changes in MMECs by inhibiting TNF-α, IL-1β, IL-6, and TLR4 and blocking the TLR4/NF-κB/MAPK signaling pathway [122].