Synthesis and evaluation of stimulatory properties of Sphingomonadaceae glycolipids

Department of Chemistry and Biochemistry, C100 BNSN, Brigham Young University, Provo, Utah 84602, USA.
Nature Chemical Biology (Impact Factor: 13). 07/2007; 3(9):559-564. DOI: 10.1038/nchembio.2007.19


Glycosphingolipids (GSLs) from the Sphingomonadaceae family of bacteria have been reported to be potent stimulators of natural killer T cells. These glycolipids include mono-, tri- and tetraglycosylceramides. Here we have prepared the GSL-1 to GSL-4 series of glycolipids and tested their abilities to stimulate natural killer T cells. Among these glycolipids, only GSL-1 (Compound 1) is a potent stimulator. Using a series of synthetic diglycosylceramides, we show that oligoglycosylceramides from Sphingomonadaceae are not effectively truncated to GSL-1 in lysosomes in antigen-presenting cells, possibly because the higher-order GSLs are poor substrates for lysosomal acyltransfer enzymes.

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Available from: Shenglou Deng, Oct 25, 2014
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    • "This observation was unexpected for two reasons: (1) additional sugars attached to α-GalCer are enzymatically removed in the lysosome revealing antigenic α-GalCer, and it was expected that a similar process would occur with the higher ordered GSLs revealing GSL-1, and (2) in an earlier report, [34] isolated GSL-4 was reported as a potent iNKT cell antigen. Using glycolipids where the sugars found in GSL-3 and GSL-4 were appended on α-GalCer, Long et al. [35] showed that lysosomal truncation of GSL-3 or GSL-4 to GSL-1 did not readily occur. Therefore, it is likely that the isolated GSL-4 was contaminated with GSL-1. "
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    ABSTRACT: Natural killer T (NKT) cells are a subset of T cells that recognize glycolipid antigens presented by the CD1d protein. The initial discovery of immunostimulatory glycolipids from a marine sponge and the T cells that respond to the compounds has led to extensive research by chemists and immunologists to understand how glycolipids are recognized, possible responses by NKT cells, and the structural features of glycolipids necessary for stimulatory activity. The presence of this cell type in humans and most mammals suggests that it plays critical roles in antigen recognition and the interface between innate and adaptive immunity. Both endogenous and exogenous natural antigens for NKT cells have been identified, and it is likely that glycolipid antigens remain to be discovered. Multiple series of structurally varied glycolipids have been synthesized and tested for stimulatory activity. The structural features of glycolipids necessary for NKT cell stimulation are moderately well understood, and designed compounds have proven to be much more potent antigens than their natural counterparts. Nevertheless, control over NKT cell responses by designed glycolipids has not been optimized, and further research will be required to fully reveal the therapeutic potential of this cell type.
    Full-text · Article · Dec 2013 · Molecules
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    • "A characteristic feature of iNKT cells is their selectivity for glycolipid antigens presented by the nonpolymorphic MHC class I-like molecule CD1d, which has been used to modulate different immune responses by exogenous agonists [10], [11], [12]. We chose to study the effect of GSL-1, a monoglycosylceramide obtained from Sphingomonas ssp. with a pro-Th1 nature, on FSGS pathogenesis [13]. To this end, we used an experimental model that is based on the susceptibility of podocytes to the cytotoxic effects of doxorubicin hydrochloride, also known as adriamycin (ADM) [14]. "
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    ABSTRACT: A growing body of evidence demonstrates a correlation between Th2 cytokines and the development of focal and segmental glomerulosclerosis (FSGS). Therefore, we hypothesized that GSL-1, a monoglycosylceramide from Sphingomonas ssp. with pro-Th1 activity on invariant Natural Killer T (iNKT) lymphocytes, could counterbalance the Th2 profile and modulate glomerulosclerosis. Using an adriamycin(ADM)-based model of FSGS, we found that BALB/c mice presented albuminuria and glomerular degeneration in association with a Th2-like pro-fibrogenic profile; these mice also expressed a combination of inflammatory cytokines, such as IL-4, IL-1α, IL-1β, IL-17, TNF-α, and chemokines, such as RANTES and eotaxin. In addition, we observed a decrease in the mRNA levels of GD3 synthase, the enzyme responsible for GD3 metabolism, a glycolipid associated with podocyte physiology. GSL-1 treatment inhibited ADM-induced renal dysfunction and preserved kidney architecture, a phenomenon associated with the induction of a Th1-like response, increased levels of GD3 synthase transcripts and inhibition of pro-fibrotic transcripts and inflammatory cytokines. TGF-β analysis revealed increased levels of circulating protein and tissue transcripts in both ADM- and GSL-1-treated mice, suggesting that TGF-β could be associated with both FSGS pathology and iNKT-mediated immunosuppression; therefore, we analyzed the kidney expression of phosphorylated SMAD2/3 and SMAD7 proteins, molecules associated with the deleterious and protective effects of TGF-β, respectively. We found high levels of phosphoSMAD2/3 in ADM mice in contrast to the GSL-1 treated group in which SMAD7 expression increased. These data suggest that GSL-1 treatment modulates the downstream signaling of TGF-β through a renoprotective pathway. Finally, GSL-1 treatment at day 4, a period when proteinuria was already established, was still able to improve renal function, preserve renal structure and inhibit fibrogenic transcripts. In conclusion, our work demonstrates that the iNKT agonist GSL-1 modulates the pathogenesis of ADM-induced glomerulosclerosis and may provide an alternative approach to disease management.
    Full-text · Article · Mar 2012 · PLoS ONE
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    • "The immunomodulatory activities of the two sphingomonads presented in this study also do not come as a surprise. Glycosphingolipids are a class of compounds that have been shown to serve as immunomodulatory agents (Long et al. 2007). The substance KRN7000, a synthetic analog of the natural product agelasphin 9b from the sponge Agelas mauritianus, is one such example and is currently in clinical trials for its capacity to stimulate NKT cells (Park et al. 2010). "
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    ABSTRACT: Marine sponges and their associated bacteria have been proven to be a rich source of novel secondary metabolites with therapeutic usefulness in cancer, infection, and autoimmunity. In this study, 79 strains belonging to 20 genera of the order Actinomycetales and seven strains belonging to two genera of the order Sphingomonadales were cultivated from 18 different Caribbean sponges and identified by 16S rRNA gene sequencing. Seven of these strains are likely to represent novel species. Crude extracts from selected strains were found to exhibit protease inhibition against cathepsins B and L, rhodesain, and falcipain-2 as well as immunomodulatory activities such as induction of cytokine release by human peripheral blood mononuclear cells. These results highlight the significance of marine sponge-associated bacteria to produce bioactive secondary metabolites with therapeutic potential in the treatment of infectious diseases and disorders of the immune system.
    Full-text · Article · Oct 2011 · Marine Biotechnology
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