Upon E. coli challenge, the Nlrp3 mRNA expression was upregulated at 3, 6 and 9 h post-infection in PMECs compared with untreated control cells (p < 0.001), but this increase was attenuated by L. johnsonii L531 pretreatment (p < 0.001, p < 0.001, and p = 0.038, respectively; Figure 3B). This evidence concerns the gene NLRP3 and infection.