Amelioration of Listeria monocytogenes infection in mice by live and pasteurized Faecalibacterium prausnitzii and its cell-free supernatant and its association with strengthened gut barrier and downregulated TLR4/NF-κB pathway

Abstract Listeria monocytogenes is a common foodborne pathogen that poses a serious health risk. Faecalibacterium prausnitzii is one of the major members of the gut microbiota and is considered essential for maintaining gut health. The aim of this study was to investigate the effect of live F. prausnitzii (FP), pasteurized F. prausnitzii (pFP) and its cell-free supernatant (CFS) on the susceptibility of mice to L. monocytogenes infection and to explore the underlying mechanisms. Safety evaluation results indicated that FP, pFP, and CFS showed no toxic effects in healthy mice. In L. monocytogenes -infected mice, these treatments significantly decreased bacterial counts in various organs and feces, and alleviated inflammation. Furthermore, the interventions significantly upregulated short-chain fatty acid (SCFA) levels, particularly acetate and propionate, and modulated the gut microbiota composition after infection. In addition, RT-qPCR and western blot results showed that they reduced inflammatory factors and intestinal damage, which is associated with downregulation of the TLR4/NF-κB pathway. Taken together, these results suggest that FP, pFP and CFS attenuate L. monocytogenes infection in mice and could be potentially developed as an alternate strategy for prevention or mitigation of L. monocytogenes .