Beta-(1-->3)-D-glucan modulates DNA binding of nuclear factors kappaB, AT and IL-6 leading to an anti-inflammatory shift of the IL-1beta/IL-1 receptor antagonist ratio.
BACKGROUND
Beta-1-->3-D-glucans represent a pathogen-associated molecular pattern and are able to modify biological responses. Employing a comprehensive methodological approach, the aim of our in vitro study was to elucidate novel molecular and cellular mechanisms of human peripheral blood immune cells mediated by a fungal beta-1-->3-D-glucan, i.e. glucan phosphate, in the presence of lipopolysaccharide (LPS) or toxic shock syndrome toxin 1 (TSST-1).


RESULTS
Despite an activation of nuclear factor (NF) kappaB, NFinterleukin(IL)-6 and NFAT similar to LPS or TSST-1, we observed no significant production of IL-1beta, IL-6, tumor necrosis factor alpha or interferon gamma induced by glucan phosphate. Glucan phosphate-treated leukocytes induced a substantial amount of IL-8 (peak at 18 h: 5000 pg/ml), likely due to binding of NFkappaB to a consensus site in the IL-8 promoter. An increase in IL-1receptor antagonist (RA) production (peak at 24 h: 12000 pg/ml) by glucan phosphate-treated cells positively correlated with IL-8 levels. Glucan phosphate induced significant binding to a known NFIL-6 site and a new NFAT site within the IL-1RA promoter, which was confirmed by inhibition experiments. When applied in combination with either LPS or TSST-1 at the same time points, we detected that glucan phosphate elevated the LPS- and the TSST-1-induced DNA binding of NFkappaB, NFIL-6 and NFAT, leading to a synergistic increase of IL-1RA. Further, glucan phosphate modulated the TSST-1-induced inflammatory response via reduction of IL-1beta and IL-6. As a consequence, glucan phosphate shifted the TSST-1-induced IL-1beta/IL-1RA ratio towards an anti-inflammatory phenotype. Subsequently, glucan phosphate decreased the TSST-1-induced, IL-1-dependent production of IL-2.


CONCLUSIONS
Thus, beta-1-->3-D-glucans may induce beneficial effects in the presence of pro-inflammatory responses, downstream of receptor binding and signaling by switching a pro- to an anti-inflammatory IL-1RA-mediated reaction. Our results also offer new insights into the complex regulation of the IL-1RA gene, which can be modulated by a beta-1-->3-D-glucan.
Institute of Immunology and Transfusion Medicine, Medical School, University of Lübeck, Germany. luhm@immu.mu-luebeck.de
Juergen
J
Luhm
Ulrich
U
Langenkamp
Jenny
J
Hensel
Christoph
C
Frohn
Joerg M
JM
Brand
Holger
H
Hennig
Lothar
L
Rink
Petra
P
Koritke
Nadine
N
Wittkopf
David L
DL
Williams
Antje
A
Mueller
D001427:Bacterial Toxins / Q000494:pharmacology; D001665:Binding Sites; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D016384:Consensus Sequence; D004247:DNA / Q000378:metabolism*; D004357:Drug Synergism; D024202:Electrophoretic Mobility Shift Assay; D004768:Enterotoxins / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D015151:Immunoblotting; D007249:Inflammation / Q000235:genetics* / Q000378:metabolism; D007371:Interferon-gamma / Q000096:biosynthesis / Q000235:genetics; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1 / Q000096:biosynthesis* / Q000235:genetics; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D016209:Interleukin-8 / Q000096:biosynthesis / Q000235:genetics; D007378:Interleukins / Q000235:genetics; D007963:Leukocytes, Mononuclear / Q000187:drug effects* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D050778:NFATC Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000187:drug effects; D011509:Proteoglycans; D012795:Sialoglycoproteins / Q000096:biosynthesis* / Q000235:genetics; D018089:Superantigens / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000235:genetics; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics; D047071:beta-Glucans / Q000494:pharmacology*
D001427:Bacterial Toxins; D004768:Enterotoxins; C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D007375:Interleukin-1; D015850:Interleukin-6; D016209:Interleukin-8; D007378:Interleukins; D008070:Lipopolysaccharides; D016328:NF-kappa B; D050778:NFATC Transcription Factors; C494006:NFATC2 protein, human; D011509:Proteoglycans; D012795:Sialoglycoproteins; D018089:Superantigens; C508960:TGFB1 protein, human; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D014409:Tumor Necrosis Factor-alpha; D047071:beta-Glucans; C030107:enterotoxin F, Staphylococcal; C010770:polysaccharide-K; D007371:Interferon-gamma; D004247:DNA