Compared with untreated control cells, the mRNA expression of Tlr4 was increased in cells infected with E. coli alone at 6 and 9 h after challenge (p < 0.001 and p < 0.001, respectively; Figure 3A), whereas L. johnsonii L531 pretreatment prior to E. coli infection led to a decrease in Tlr4 mRNA expression in PMECs in comparision to cells only infected with E. coli at 6 and 9 h (p = 0.002 and p = 0.003, respectively). This evidence concerns the gene TLR4 and escherichia coli infection.