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].…”

Carnosol ameliorates sevoflurane induced cognitive impairment in aged rats by suppressing NLRP3 inflammasome via activation of autophagy

“…Activation of autophagy suppresses the formation of NLRP3 inflammasome [10]. NLRP3 inflammasome is highly expressed and over-activated in aged rats, and is vital in the central inflammatory response [18]. Over-activation of NLRP3 inflammasome leads to a variety of diseases, including POCD [10].…”

Exploring the potential of Lactocaseibacillus rhamnosus PMC203 in inducing autophagy to reduce the burden of Mycobacterium tuberculosis

“…For instance, Wu et al, 2017 demonstrated that heat-killed Probiotic Bacillus amyloliquefaciens SC06 can stimulate autophagy and protect macrophages against Escherichia coli [ 52 ]. Likewise, another study showed that heat- killed Lactobacillus plantarum markedly triggered autophagy in response to Salmonella intracellular infection [ 53 ]. Therefore, the potentiality of heat killed probiotic bacteria in triggering autophagy led us to utilize heat-killed PMC203 in our study.…”