Lipopolysaccharide associated with β-2, 6 fructan mediates TLR4-dependent immunomodulatory activity in vitro. (1st February 2022)

• Record Type: Journal Article
• Authors: Young, Ian D.; Nepogodiev, Sergey A.; Black, Ian M.; Le Gall, Gwenaelle; Wittmann, Alexandra; Latousakis, Dimitrios; Visnapuu, Triinu; Azadi, Parastoo; Field, Robert A.; Juge, Nathalie; Kawasaki, Norihito
• Is Part Of: Carbohydrate polymers. Volume 277(2022)
• Publication Date: 2022-02-01
• Subjects: AP-1 Activator protein 1 -- BMDCs bone marrow-derived dendritic cells -- ES enzymatically synthesised -- EU endotoxin unit -- GC-MS gas chromatography–mass spectrometry -- GPC gel permeation chromatography -- HBSS Hanks's balanced saline solution -- IL interleukin -- KO knockout -- NF-κB nuclear factor kappa B -- MD-2 Myeloid Differentiation protein 2 -- MyD88 myeloid differentiation primary response 88 -- PS polysaccharide -- SEAP Secreted embryonic alkaline phosphatase -- TLR4 toll-like receptor 4 -- TLRs toll-like receptors -- TNF-α tumour necrosis factor alpha -- TRIF TIR-domain-containing adapter-inducing interferon-β -- TRAM TRIF-related adapter molecule -- WT wild type; Levan -- Immunomodulatory exopolysaccharide -- Fructan -- Lipopolysaccharide -- TLR4; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2021.118606
• Languages: English
• ISSNs: 0144-8617

Abstract

Abstract: Levan, a β-2, 6 fructofuranose polymer produced by microbial species, has been reported for its immunomodulatory properties via interaction with toll-like receptor 4 (TLR4) which recognises lipopolysaccharide (LPS). However, the molecular mechanisms underlying these interactions remain elusive. Here, we investigated the immunomodulatory properties of levan using thoroughly-purified and characterised samples from Erwinia herbicola and other sources. E. herbicola levan was purified by gel-permeation chromatography and LPS was removed from the levan following a novel alkali treatment developed in this study. E. herbicola levan was then characterised by gas chromatography–mass spectrometry and NMR. We found that levan containing LPS, but not LPS-depleted levan, induced TLR4-mediated cytokine production by bone marrow-derived dendritic cells and/or activated TLR4 reporter cells. These data indicated that the immunomodulatory properties of the levan toward TLR4-expressing immune cells were mediated by the LPS. This work also demonstrates the importance of LPS removal when assessing the immunomodulatory activity of polysaccharides. Highlights: E. herbicola levan stimulates dendritic cells in a TLR4-dependent manner. LPS depletion from levans is achieved by a novel alkali-based purification method. LPS mediates E. herbicola levan-induced cytokine production from dendritic cells.