Abstract
Compounds of the cell walls of heat-killed lactic acid bacteria show immunomodulatory properties which boost immunological systems, and are used ad postbiotics (paraprobiotics). In this study, we used 17 different heat-killed isolates as postbiotics and evaluated their anti-inflammatory potential on the expression of proinflammatory mediators and cellular signaling pathways of murine macrophage, RAW 264.7 cells. Bifidobacterium bifidum MG731 showed the high 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity (90.6%), followed by Bifidobacterium lactis MG741 (59.6%). The Bi. lactis MG741 showed the high ABTS free radical scavenging activity (99.5%), followed by Lactobacillus plantarum MG989 (98.9%), Lactobacillus salivarius MG242 (97.1%), and Bi. bifidum MG731 (96.1%). In addition, Bi. bifidum MG731 showed the lowest nitric oxide production (4.28 µM), followed by B. lactis MG741 (10.80 µM), L. salivarius MG242 (14.60 µM), and L. plantarum MG989 (19.60 µM). The selected strains showed a decreased nitric oxide production via downregulation of inducible nitric oxide synthase and cyclooxygenase 2, which were upregulated via LPS-stimulated RAW 264.7 macrophages. Short-chain fatty acids (SCFA) including acetic, propionic, and butyric acid were produced by four strains. The Bi. bifidum MG731 showed total SCFAs production (4998.6 µg/g), Bi. lactis MG741 (2613.9 µg/g), L. salivarius MG242 (1456.1 µg/g), and L. plantarum MG989 (630.2 µg/g). These results indicated that the various selected strains may possess an anti-inflammatory potential and provide a molecular basis for the development of functional probiotics.
Highlights
Probiotics are defined as “living microorganisms that have health benefits beyond inherent basic nutrition” when consumed in certain quantities (Klein et al 1998; Rendondo et al 2019)
Following centrifugation (12,000 × g, 5 min), the cell pellets were rinsed thrice with phosphate-buffered saline (PBS) and suspended in Dulbecco’s modified Eagle media (DMEM) (BD Biosciences) to obtain concentrations of 5 × 1 08 cells/mL by adjusting the solution based on absorbance at 600 nm (OD600)
Bifidobacterium bifidum MG731 showed the highest radical scavenging activity (90.6%) followed by Bi. lactis MG741 (59.6%)
Summary
Probiotics are defined as “living microorganisms that have health benefits beyond inherent basic nutrition” when consumed in certain quantities (Klein et al 1998; Rendondo et al 2019). The mechanisms implicated in most bioactivities of postbiotics are not fully understood; scientific evidence supports that postbiotics possess diverse functional/bioactive properties such as antimicrobial, Inflammation is a complex response of the vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. It is mediated by a variety of signaling molecules produced by macrophages, monocytes, and mast cells. They can kill pathogens directly via phagocytosis and indirectly via the secretion of proinflammatory cytokines such as tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and interleukin 6 (IL-6) (Stuehr et al 1991; Kazemi et al 2019), as well as excess amounts of mediators such as nitric
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