Lacticaseibacillus paracasei FL5 Inhibits Helicobacter pylori by Regulating Gastric Microbiota and NF-κB Signaling Pathway.

Lacticaseibacillus paracasei FL5 was identified as the most potent H. pylori antagonist among tested strains.

• FL5 showed excellent coaggregation rate of 97.93% with H. pylori
• Cell surface hydrophobicity exceeded 50%
• Urease inhibition reached 77.58%
• FL5 produced a 22.00 mm inhibition zone against H. pylori

FL5 secreted metabolites induced bacterial lysis and inhibited urease activity in vitro.

• The inhibitory effects were attributed to secreted metabolites rather than direct cell contact
• Two distinct mechanisms were identified: bacterial lysis induction and urease inhibition
• These in vitro findings supported the multi-target mechanism of FL5

Both FL5 and inactivated FL5 (IFL5) reduced H. pylori colonization and treated H. pylori-induced gastritis in vivo.

• In vivo treatment with FL5 and IFL5 reduced H. pylori colonization in gastric tissue
• Both treatments regulated oxidative stress in H. pylori-infected animals
• Both treatments repaired the mucosal barrier damaged by H. pylori infection
• IFL5 refers to heat-inactivated FL5

FL5 and IFL5 modulated gastric microbial homeostasis in H. pylori-infected animals.

• Treatment with FL5 and IFL5 altered gastric microbiota composition
• The modulation of gastric microbial homeostasis was observed in vivo
• This finding suggests that the probiotic exerts effects partly through reshaping the gastric microbial community

FL5 and IFL5 attenuated inflammation via the TLR2/MyD88/NF-κB signaling pathway.

• Treatment decreased pro-inflammatory cytokines TNF-α, IL-1β, IL-6, and CXCL1
• Treatment increased anti-inflammatory markers IL-10, IL-4, and IgG
• The signaling pathway identified was TLR2/MyD88/NF-κB
• Both live and inactivated forms demonstrated immunomodulatory activity

Inactivated FL5 (IFL5) demonstrated superior efficacy compared to live FL5 in inhibiting TLR2/NF-κB signaling.

• IFL5 showed greater inhibition of TLR2/NF-κB signaling than live FL5
• This finding highlights the retained immunomodulatory activity of the heat-inactivated derivative
• The superior performance of IFL5 in this pathway was described as an unexpected or noteworthy finding, noted with 'interestingly' by the authors