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  • 1
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract The effects of synthetic alkyl ((alkyl 6-deoxy-a-d-gluco-heptopyranosyluronate) 6-deoxy-a-D-gluco-heptopyranoside) uronates, a novel type of mirror pseudo cord factor, on the in vitro modulation of interleukin-6 production and T-cell proliferation in human peripheral blood mononuclear cells, were investigated. Synthetic mirror pseudo cord factors with alkyl chains ranging from C16 to C18 have very weak interleukin-6-inducing capacities and lack mitogenic activities for T-cell proliferation. However, they could inhibit IL-6 release induced by sonicated Bacillus Calmette-Guérin (S-BCG), bacterial endotoxin, and phytohaemagglutinin in a dose-dependent manner. Inhibition was observed not only with mononuclear cells but also with purified monocytes. Furthermore, these synthetic compounds could suppress T-lymphocyte proliferation stimulated by sonicated Mycobacterium tuberculosis H37Rv (S-H37Rv) antigens, S-BCG antigens, as well as by recombinant 65 kDa mycobacterial heat-shock protein. In contrast, these compounds failed to inhibit the phytohaemagglutinin-induced T-cell proliferation. We conclude that the inhibition of cytokine release and T-cell proliferation by synthetic mirror pseudo cord factors was due to direct blocking of the function and/or activity of monocytes or antigen-presenting cells.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Endotoxin (lipopolysaccharide, LPS) induces the production of mediators of inflammation, which exerts pathophysiological effects such as fever or shock in mammals. In the present study we have investigated the modulation of LPS by the synthetic non-active tetraacylated precursor Ia of lipid A (compound 406) in the induction of tumor necrosis factor (TNF), interleukin 1 (IL-1) and interleukin 6 (IL-6) in human peripheral blood mononuclear cells (PBMC) and in human peripheral blood monocytes (PBMo). PBMC stimulated with LPS released TNF in a concentration dependent manner. Release of biologically active TNF, IL-1 and IL-6 was first detectable 4 h after LPS stimulation. Compound 406 alone in all concentrations tested did not induce TNF, IL-1 or IL-6 release, intracellular TNF or IL-1β, or mRNA for TNF or IL-1. Added to PBMC 1 h before LPS compound 406 enhanced or suppressed TNF release and suppressed IL-1 and IL-6 release depending on the ratio of concentrations between stimulator (LPS) and modulator (compound 406). In contrast to LPS stimulation alone TNF, IL-1 and IL-6 release in presence of compound 406 was delayed and first detectable after 6 to 8 h. Compound 406 was able to suppress LPS-induced intracellular TNF and IL-1β in PBMC. Added to PBMo 1 h before LPS it totally inhibited the production of mRNA for TNF and IL-1. When added to PBMC 1 h after LPS, TNF release was suppressed in a concentration-dependent way and release of biologically active TNF, IL-1 and IL-6 could again be detected for the first time after 4 h. Compound 406 was not able to inhibit phorbol 12-myristate 13-acetate (PMA)-induced TNF and IL-1 release in PBMo which suggests that its modulating effect is LPS-specific. This study provides evidence that the modulating effect of compound 406 on the LPS induction of TNF, IL-, 1 and IL-6 could be due to competitive binding.
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  • 3
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Experiments were designed to investigate the significance of lipid A partial structures, precursor Ia (compound 406), and lipid X (compound 401) to serve as antagonists of interleukin 1 (IL-1) release from human mononuclear cells and monocytes induced by lipopolysaccharide (LPS, endotoxin) of Salmonella aborus equi or synthetic Escherichia coli lipid A (compound 506). A definite inhibition mediated by lipid A partial structures on IL-1 release induced by LPS or lipid A was found in repeated experiments. The inhibitory effect was exterted not only on IL-1 release, but also on IL-1 peptide synthesis at the intracellular level. The results also show that lipid A partial structures have suppressive effects even when added 1–4 after LPS or lipid A. We conclude from these results that lipis A partial structures (precursor Ia and lipid X) have potent immunomodulatory effects on LPS- and lipid A-induced IL-1 release and may become useful reagents to study the mechanism of interaction of LPS and lipid A with cells of the immune system.
    Type of Medium: Electronic Resource
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