Lactobacillus rhamnosus and its cell-free culture supernatant differentially modulate inflammatory biomarkers in Escherichia coli-challenged human dendritic cells.
The intestinal immune system maintains a delicate balance between immunogenicity against invading pathogens and tolerance to the commensal microbiota and food antigens. Different strains of probiotics possess the ability to finely regulate the activation of dendritic cells (DC), polarising the subsequent activity of T-cells. Nevertheless, information about their underlying mechanisms of action is scarce. In the present study, we investigated the immunomodulatory effects of a potentially probiotic strain, Lactobacillus rhamnosus CNCM I-4036, and its cell-free culture supernatant (CFS) on human DC challenged with Escherichia coli. The results showed that the levels of pro-inflammatory cytokines such as IL-1β, IL-6, IL-8 and IL-12p70 were higher in the cells treated with live L. rhamnosus than in the cells treated with the CFS. In the presence of E. coli, the supernatant was more effective than the probiotic bacteria in reducing the secretion of pro-inflammatory cytokines. In addition, live L. rhamnosus potently induced the production of transforming growth factor (TGF)-β1 and TGF-β2, whereas the CFS increased the secretion of TGF-β1. However, in the presence of E. coli, both treatments restored the levels of TGF-β. The probiotic strain L. rhamnosus CNCM I-4036 and its CFS were able to activate the Toll-like receptor signalling pathway, enhancing innate immunity. The two treatments induced gene transcription of TLR-9. Live L. rhamnosus activated the expression of TLR-2 and TLR-4 genes, whereas the CFS increased the expression of TLR-1 and TLR-5 genes. In response to the stimulation with probiotic/CFS and E. coli, the expression of each gene tested was notably increased, with the exception of TNF-α and NFKBIA. In conclusion, the CFS exhibited an extraordinary ability to suppress the production of pro-inflammatory cytokines by DC, and may be used as an effective and safer alternative to live bacteria.
Department of Biochemistry and Molecular Biology II, Institute of Nutrition and Food Technology "José Mataix" (INyTA), Biomedical Research Center, University of Granada, Avenida del Conocimiento s/n, Armilla 18100, Granada, Spain.
Miriam
M
Bermudez-Brito
Department of Biochemistry and Molecular Biology II, Institute of Nutrition and Food Technology "José Mataix" (INyTA), Biomedical Research Center, University of Granada, Avenida del Conocimiento s/n, Armilla 18100, Granada, Spain.
Sergio
S
Muñoz-Quezada
Department of Biochemistry and Molecular Biology II, Institute of Nutrition and Food Technology "José Mataix" (INyTA), Biomedical Research Center, University of Granada, Avenida del Conocimiento s/n, Armilla 18100, Granada, Spain.
Carolina
C
Gomez-Llorente
Hero Global Technology Centre For Infant Nutrition, Hero Group, Avenida del Murcia 1, Alcantarilla 30820, Murcia, Spain.
Fernando
F
Romero
Department of Biochemistry and Molecular Biology II, Institute of Nutrition and Food Technology "José Mataix" (INyTA), Biomedical Research Center, University of Granada, Avenida del Conocimiento s/n, Armilla 18100, Granada, Spain.
Angel
A
Gil
D015415:Biomarkers / Q000378:metabolism; D018929:Cell Culture Techniques; D002474:Cell-Free System / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D003713:Dendritic Cells / Q000166:cytology* / Q000276:immunology / Q000382:microbiology; D004926:Escherichia coli / Q000302:isolation & purification*; D015870:Gene Expression; D006801:Humans; D007118:Immunoassay; D007422:Intestines / Q000276:immunology / Q000382:microbiology*; D052201:Lacticaseibacillus rhamnosus / Q000276:immunology / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D019936:Probiotics / Q000378:metabolism*; D015398:Signal Transduction; D051193:Toll-Like Receptors / Q000235:genetics
D015415:Biomarkers; D016207:Cytokines; D051193:Toll-Like Receptors