Immunomodulatory activity of heat-killed Lacticaseibacillus paracaseiMCC1849 based on the activation of plasmacytoid dendritic cells in the peripheral blood of healthy adults.

2024-02-07
Food science & nutrition 12(5)

PubMed: 38726445
DOI: 10.1002/fsn3.4009

Study Design

Population: human peripheral blood mononuclear cells (PBMCs)
Methods: human peripheral blood mononuclear cells (PBMCs) were cocultured with heat-killed Lacticaseibacillus paracasei MCC1849 (hk-MCC1849); DCs were enriched with PBMCs following 24 h of coculture with hk-MCC1849

Probiotics are widely used in food for their health benefits to the host. Inactivated probiotics also reportedly improve the intestinal environment and immune regulation. Our previous studies showed that heat-killed Lacticaseibacillus paracasei MCC1849 (hk-MCC1849) effectively induced IL-12 production in mouse spleen cells and significantly reduced cold symptoms in clinical trial subjects. To further elucidate the mechanism of host immune regulation by hk-MCC1849, human peripheral blood mononuclear cells (PBMCs) were cocultured with hk-MCC1849. The Toll-like receptor 9 ligands CpG-ODN 2216 and hk-MCC1849 and the heat-killed Lacticaseibacillus rhamnosus ATCC53103 were used as positive and negative controls, respectively. The results showed that, compared with the control, hk-MCC1849 significantly increased the expression of the plasmacytoid dendritic cell (pDC) marker CD86 (p < .0001) and the pDC marker HLA-DR (p < .001) in PBMCs. The expression levels of the IL-12p40, IFNα, IFNα1, IFNγ, and ISG15 genes were significantly increased after coculture with hk-MCC1849 (p < .05, p < .05, p < .05, p < .05, and p < .05, respectively, vs. control). Furthermore, to confirm whether hk-MCC1849 directly interacted with pDCs, DCs were enriched with PBMCs following 24 h of coculture with hk-MCC1849. Phagocytosis of fluorescently labeled hk-MCC1849 by pDCs was observed, and there were significant increases in CD86 (p < .05) and HLA-DR (p < .0001) expression in pDCs. These results suggest that hk-MCC1849 exerts a potential immunomodulatory effect on the host through the activation of peripheral pDCs.

Research Insights

Supplement	Dose	Health Outcome	Effect Type	Effect Size	Source
Lactobacillus paracasei MCC1849	—	Increased Immune System Activation	Beneficial	Moderate	View source hk-MCC1849 significantly increased the expression of the plasmacytoid dendritic cell (pDC) marker CD86 ... and the pDC marker HLA-DR ... The expression levels of the IL-12p40, IFNα, IFNα1, IFNγ, and ISG15 genes were significantly increased after coculture with hk-MCC1849
Lactobacillus paracasei MCC1849	—	Reduced Cold Symptoms	Beneficial	Moderate	View source hk-MCC1849 effectively induced IL-12 production in mouse spleen cells and significantly reduced cold symptoms in clinical trial subjects.