Probiotic Pediococcus acidilactici Strains Exert Anti-inflammatory Effects by Regulating Intracellular Signaling Pathways in LPS-Induced RAW 264.7 Cells.

This study investigated the anti-inflammatory effects of Pediococcus acidilactici strains isolated from fermented vegetables on lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. In addition, the probiotic characteristics and safety were evaluated. Our results show that Ped. acidilactici strains possess high survivability in simulated gastrointestinal environments and strong attachment to HT-29 cells. All Ped. acidilactici strains exhibited γ-hemolysis and resistance to gentamicin, kanamycin, and streptomycin, a characteristic commonly observed in lactic acid bacteria. Treatment with Ped. acidilactici inhibited the expression of inducible nitric oxide synthase and cyclooxygenase-2, leading to a subsequent reduction in nitric oxide and prostaglandin E2 production. Furthermore, the strains downregulated interleukin (IL)-1ß and IL-6 mRNA levels, ultimately suppressing their production. We demonstrated that Ped. acidilactici strains could modulate the activation of nuclear factor-κB, mitogen-activated protein kinase, and activator protein-1, which are known to regulate inflammatory responses. Consequently, the anti-inflammatory properties of Ped. acidilactici strains in this study support their potential application as therapeutic agents for inflammatory diseases, providing molecular insights into next-generation functional probiotic products.

Heat-Treated Paraprobiotic Latilactobacillus sakei KU15041 and Latilactobacillus curvatus KU15003 Show an Antioxidant and Immunostimulatory Effect.

The lactic acid bacteria, including Latilactobacillus sakei and Latilactobacillus curvatus, have been widely studied for their preventive and therapeutic effects. In this study, the underlying mechanism of action for the antioxidant and immunostimulatory effects of two strains of heat-treated paraprobiotics was examined. Heat-treated L. sakei KU15041 and L. curvatus KU15003 showed higher radical scavenging activity in both the 2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assays than the commercial probiotic strain LGG. In addition, treatment with these two strains exhibited immunostimulatory effects in RAW 264.7 macrophages, with L. curvatus KU15003 showing a slightly higher effect. Additionally, they promoted phagocytosis and NO production in RAW 264.7 cells without any cytotoxicity. Moreover, the expression of tumor necrosis factor-α, interleukin (IL)-1ß, and IL-6 was upregulated. These strains resulted in an increased expression of inducible nitric oxide synthase and cyclooxygenase-2. Moreover, the nuclear factor-κB and mitogen-activated protein kinase signaling pathways were stimulated by these strains. These findings suggest the potential of using L. sakei KU15041 and L. curvatus KU15003 in food or by themselves as probiotics with antioxidant and immune-enhancing properties.

Anti-inflammatory activities of Levilactobacillus brevis KU15147 in RAW 264.7 cells stimulated with lipopolysaccharide on attenuating NF-κB, AP-1, and MAPK signaling pathways.

Probiotics confer many beneficial effects on several illnesses, ranging from microbial diarrhea to inflammatory diseases. This study was conducted on whether Levilactobacillus brevis KU15147 obtained from kimchi has anti-inflammatory effects in RAW 264.7 cells stimulated with lipopolysaccharide (LPS) and antioxidant potential. L. brevis KU15147 reduced nitric oxide and prostaglandin E2 levels with decreasing the activation of inducible nitric oxide synthase and cyclooxygenase-2 without cell cytotoxicity. In addition, L. brevis KU15147 attenuated proinflammatory cytokine production including tumor necrosis factor-α, interleukin (IL)-1ß, and IL-6 in RAW 264.7 cells stimulated with LPS. Additionally, L. brevis KU15147 reduced the activity of nuclear factor-κB, activator protein-1, and mitogen-activated protein kinase signaling pathways. Furthermore, L. brevis KU15147 downregulated the production of reactive oxygen species. Therefore, L. brevis KU15147 was concluded that had an inhibition effect on LPS-induced inflammatory responses and can be used in functional foods to suppress inflammatory diseases. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01318-w.