A novel rhamnose-rich hetero-exopolysaccharide isolated from Lactobacillus paracasei DG activates THP-1 human monocytic cells

Silvia Balzaretti, Valentina Taverniti, Simone Guglielmetti, Walter Fiore, Mario Minuzzo, Hansel N. Ngo, Judith B. Ngere, Sohaib Sadiq, Paul N Humphreys, Andrew P. Laws

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Abstract

Lactobacillus paracasei DG is a bacterial strain with recognized probiotic properties and is used in commercial probiotic products. However, the mechanisms underlying its probiotic properties are mainly unknown. In this study, we tested the hypothesis that the capability of strain DG to interact with the host is, at least partly, associated with its ability to synthesize a surface-associated exopolysaccharide (EPS). Comparative genomics revealed the presence of putative EPS gene clusters in DG genome; accordingly, EPS was isolated from the surface of the bacterium. A sample of the pure EPS from strain DG (DG-EPS), upon NMR and chemical analyses, was shown to be a novel branched hetero-EPS with a repeat unit composed of L-rhamnose, D-galactose, and N-acetyl-D-galactosamine in a ratio of 4:1:1. Subsequently, we demonstrated that the DG-EPS displays immunostimulating properties by enhancing the gene expression of the pro-inflammatory cytokines TNF-alpha and IL-6, and, particularly, the chemokines IL-8 and CCL20 in the THP-1 human monocytic cell line. In contrast, the expression of the cyclooxygenase enzyme COX-2 was not affected. In conclusion, the DG-EPS is a bacterial macromolecule with the potential ability to boost the immune system as either a secreted molecule released from the bacterium or as a capsular envelope on the bacterial cell wall. This study provides additional information about the mechanisms supporting the cross-talk between L. paracasei DG and the host.
LanguageEnglish
PagesAEM.02702-16
Number of pages28
JournalApplied and Environmental Microbiology
Volume83
Issue number2
Early online date2 Dec 2016
DOIs
Publication statusPublished - 1 Jan 2017

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Lactobacillus paracasei
Rhamnose
probiotics
exopolysaccharides
rhamnose
Probiotics
Bacteria
Acetylgalactosamine
bacterium
immune system
cells
Prostaglandin-Endoperoxide Synthases
Multigene Family
Genomics
Interleukin-8
Galactose
Chemokines
Cell Wall
gene expression
nuclear magnetic resonance

Cite this

Balzaretti, Silvia ; Taverniti, Valentina ; Guglielmetti, Simone ; Fiore, Walter ; Minuzzo, Mario ; Ngo, Hansel N. ; Ngere, Judith B. ; Sadiq, Sohaib ; Humphreys, Paul N ; Laws, Andrew P. / A novel rhamnose-rich hetero-exopolysaccharide isolated from Lactobacillus paracasei DG activates THP-1 human monocytic cells. In: Applied and Environmental Microbiology. 2017 ; Vol. 83, No. 2. pp. AEM.02702-16.
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A novel rhamnose-rich hetero-exopolysaccharide isolated from Lactobacillus paracasei DG activates THP-1 human monocytic cells. / Balzaretti, Silvia; Taverniti, Valentina; Guglielmetti, Simone; Fiore, Walter; Minuzzo, Mario; Ngo, Hansel N.; Ngere, Judith B.; Sadiq, Sohaib; Humphreys, Paul N; Laws, Andrew P.

In: Applied and Environmental Microbiology, Vol. 83, No. 2, 01.01.2017, p. AEM.02702-16.

Research output: Contribution to journalArticle

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AU - Balzaretti, Silvia

AU - Taverniti, Valentina

AU - Guglielmetti, Simone

AU - Fiore, Walter

AU - Minuzzo, Mario

AU - Ngo, Hansel N.

AU - Ngere, Judith B.

AU - Sadiq, Sohaib

AU - Humphreys, Paul N

AU - Laws, Andrew P.

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N2 - Lactobacillus paracasei DG is a bacterial strain with recognized probiotic properties and is used in commercial probiotic products. However, the mechanisms underlying its probiotic properties are mainly unknown. In this study, we tested the hypothesis that the capability of strain DG to interact with the host is, at least partly, associated with its ability to synthesize a surface-associated exopolysaccharide (EPS). Comparative genomics revealed the presence of putative EPS gene clusters in DG genome; accordingly, EPS was isolated from the surface of the bacterium. A sample of the pure EPS from strain DG (DG-EPS), upon NMR and chemical analyses, was shown to be a novel branched hetero-EPS with a repeat unit composed of L-rhamnose, D-galactose, and N-acetyl-D-galactosamine in a ratio of 4:1:1. Subsequently, we demonstrated that the DG-EPS displays immunostimulating properties by enhancing the gene expression of the pro-inflammatory cytokines TNF-alpha and IL-6, and, particularly, the chemokines IL-8 and CCL20 in the THP-1 human monocytic cell line. In contrast, the expression of the cyclooxygenase enzyme COX-2 was not affected. In conclusion, the DG-EPS is a bacterial macromolecule with the potential ability to boost the immune system as either a secreted molecule released from the bacterium or as a capsular envelope on the bacterial cell wall. This study provides additional information about the mechanisms supporting the cross-talk between L. paracasei DG and the host.

AB - Lactobacillus paracasei DG is a bacterial strain with recognized probiotic properties and is used in commercial probiotic products. However, the mechanisms underlying its probiotic properties are mainly unknown. In this study, we tested the hypothesis that the capability of strain DG to interact with the host is, at least partly, associated with its ability to synthesize a surface-associated exopolysaccharide (EPS). Comparative genomics revealed the presence of putative EPS gene clusters in DG genome; accordingly, EPS was isolated from the surface of the bacterium. A sample of the pure EPS from strain DG (DG-EPS), upon NMR and chemical analyses, was shown to be a novel branched hetero-EPS with a repeat unit composed of L-rhamnose, D-galactose, and N-acetyl-D-galactosamine in a ratio of 4:1:1. Subsequently, we demonstrated that the DG-EPS displays immunostimulating properties by enhancing the gene expression of the pro-inflammatory cytokines TNF-alpha and IL-6, and, particularly, the chemokines IL-8 and CCL20 in the THP-1 human monocytic cell line. In contrast, the expression of the cyclooxygenase enzyme COX-2 was not affected. In conclusion, the DG-EPS is a bacterial macromolecule with the potential ability to boost the immune system as either a secreted molecule released from the bacterium or as a capsular envelope on the bacterial cell wall. This study provides additional information about the mechanisms supporting the cross-talk between L. paracasei DG and the host.

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M3 - Article

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JF - Applied and Environmental Microbiology

SN - 0099-2240

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