Lactobacillus plantarum postbiotics trigger AMPK‐dependent autophagy to suppress Salmonella intracellular infection and NLRP3 inflammasome activation

Abstract

We previously found that Lactobacillus plantarum (LP)‐derived postbiotics protected animals against Salmonella infection, but the molecular mechanism remains obscure. This study clarified the mechanisms from the perspective of autophagy. Intestinal porcine epithelial cells (IPEC‐J2) were pretreated with LP‐derived postbiotics (the culture supernatant, LPC; or heat‐killed bacteria, LPB), and then challenged with Salmonella enterica Typhimurium (ST). Results showed that LP postbiotics markedly triggered autophagy under ST infection, as indicated by the increased LC3 and Beclin1 and the decreased p62 levels. Meanwhile, LP postbiotics (particularly LPC) exhibited a strong capacity of inhibiting ST adhesion, invasion and replication. Pretreatment with the autophagy inhibitor 3‐methyladenine (3‐MA) led to a significant decrease of autophagy and the aggravated infection, indicating the importance of autophagy in LP postbiotics‐mediated Salmonella elimination. LP postbiotics (especially LPB) significantly suppressed ST‐induced inflammation by modulating inflammatory cytokines (the increased interleukin (IL)‐4 and IL‐10, and decreased tumor necrosis factor‐α (TNF), IL‐1β, IL‐6 and IL‐18). Furthermore, LP postbiotics inhibited NOD‐like receptor protein 3 (NLRP3) inflammasome activation, as evidenced by the decreased levels of NLRP3, Caspase‐1 and apoptosis‐associated speck‐like protein containing a caspase recruitment domain (ASC). Deficits in autophagy resulted in an increase of inflammatory response and inflammasome activation. Finally, we found that both LPC and LPB triggered AMP‐activated protein kinase (AMPK) signaling pathway to induce autophagy, and this was further confirmed by AMPK RNA interference. The intracellular infection and NLRP3 inflammasome were aggravated after AMPK knockdown. In summary, LP postbiotics trigger AMPK‐mediated autophagy to suppress Salmonella intracellular infection and NLRP3 inflammasome in IPEC‐J2 cells. Our findings highlight the effectiveness of postbiotics, and provide a new strategy for preventing Salmonella infection.

Novel Synergistic Probiotic Intervention: Transcriptomic and Metabolomic Analysis Reveals Ameliorative Effects on Immunity, Gut Barrier, and Metabolism of Mice during Salmonella typhimurium Infection

“…This result is consistent with our finding, which revealed that the probiotic-administered group exhibited a notable enhancement in the PI3K-Akt signaling pathway (Figure 2B). Yanping Wu et al's study [67] demonstrated that L. plantarum induced AMPK-mediated autophagy to inhibit NLRP3 inflammasome and Salmonella infection in IPEC-J2 cells, consistent with our results. Furthermore, FOXO signaling pathways regulate cell growth, differentiation, death, and immunity [68].…”

Lactobacillus Plantarum Promotes Wound Healing by Inhibiting the NLRP3 Inflammasome and Pyroptosis Activation in Diabetic Foot Wounds

“… 19 LP postbiotics decreased levels of NLRP3, Caspase-1 and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) and suppressed various inflammatory cytokines against Salmonella infection. 20 …”

Lactiplantibacillus plantarum postbiotic protects against Salmonella infection in broilers via modulating NLRP3 inflammasome and gut microbiota

“…Recent studies showed that its postbiotics, including the bacterial components and metabolites, exert beneficial effects on improving nutrient intake, immune response, and gut microbiota, contributing to the promotion of growth performance and quality of animal products ( Chang et al, 2022 ; Danladi et al, 2022 ). We previously screened a strain LP HJZW08 and found that its postbiotics exhibited a strong antibacterial capacity on inhibiting Salmonella ( Wu et al, 2023 ), but whether it is effective in vivo and the molecular mechanism remains obscure. Thus, this study aimed to explore the effectiveness of LP postbiotic on alleviating Salmonella infection in broiler chickens, and elucidated the molecular mechanism from the perspective of regulating NLRP3 inflammasome and gut microbiota.…”