Convergent Synthesis of Digalactosyl Diacylglycerols

Efficient convergent chemical syntheses of digalactosyl diacylglycerols (DGDGs), which have both a galactose–galactose α(1→6)-linkage and a galactose–glycerol β-linkage along with a diacylglycerol containing various kinds of fatty acids, have been accomplished. In order to achieve a concise synthesis, we chose to use allylic protective groups as permanent protective groups. We have also achieved α- and β-selective glycosylations for the respective linkages with high yields as the key steps

Chemical Synthesis of d-<i>glycero</i>-d-<i>manno</i>-Heptose 1,7-Bisphosphate and Evaluation of Its Ability to Modulate NF-κB Activation

d-<i>glycero</i>-d-<i>manno</i>-Heptose 1,7-bisphosphate (HBP) is the precursor for heptose residues found in Gram-negative bacterial membrane surface glycoproteins and glycolipids. HBP β-anomer was recently reported to be a pathogen-associated molecular pattern (PAMP) that regulates TIFA-dependent immunity. Herein, we report the chemical synthesis of HBP α- and β-anomers, which highlights a C-7 carbon homologation via the Corey–Chaykovsky reaction, and the introduction of a phosphate group at the anomeric position using the Mitsunobu reaction. Furthermore, NF-κB reporter assaying revealed that HBP β-anomer activates the NF-κB signaling pathway

Isolated Polar Amino Acid Residues Modulate Lipid Binding in the Large Hydrophobic Cavity of CD1d

The CD1d protein is a nonpolymorphic MHC class I-like protein that controls the activation of natural killer T (NKT) cells through the presentation of self- and foreign-lipid ligands, glycolipids, or phospholipids, leading to the secretion of various cytokines. The CD1d contains a large hydrophobic lipid binding pocket: the A′ pocket of CD1d, which recognizes hydrophobic moieties of the ligands, such as long fatty acyl chains. Although lipid–protein interactions typically rely on hydrophobic interactions between lipid chains and the hydrophobic sites of proteins, we showed that the small polar regions located deep inside the hydrophobic A′ pocket could be used for the modulation of the lipid binding. A series of the ligands, α-galactosyl ceramide (α-GalCer) derivatives containing polar groups in the acyl chain, was synthesized, and the structure–activity relationship studies demonstrated that simple modification from a methylene to an amide group in the long fatty acyl chain, when introduced at optimal positions, enhanced the CD1d recognition of the glycolipid ligands. Formation of hydrogen bonds between the amide group and the polar residues was supported by molecular dynamics (MD) simulations and WaterMap calculations. The computational studies suggest that localized hydrating water molecules may play an important role in the ligand recognition. Here, the results showed that confined polar residues in the large hydrophobic lipid binding pockets of the proteins could be potential targets to modulate the affinity for its ligands

Synthetic analogs of an Entamoeba histolytica glycolipid designed to combat intracellular Leishmania infection

Intracellular pathogens belonging to the genus Leishmania have developed effective strategies that enable them to survive within host immune cells. Immunostimulatory compounds that counteract such immunological escape mechanisms represent promising treatment options for diseases. Here, we demonstrate that a lipopeptidephosphoglycan (LPPG) isolated from the membrane of a protozoan parasite, Entamoeba histolytica (Eh), shows considerable immunostimulatory effects targeted against Leishmania (L.) major, a representative species responsible for cutaneous leishmaniasis (CL). Treatment led to a marked reduction in the number of intracellular Leishmania parasites in vitro, and ameliorated CL in a mouse model. We next designed and synthesized analogs of the phosphatidylinositol anchors harbored by EhLPPG; two of these analogs reproduced the anti-leishmanial activity of the native compound by inducing production of pro-inflammatory cytokines. The use of such compounds, either alone or as a supportive option, might improve the currently unsatisfactory treatment of CL and other diseases caused by pathogen-manipulated immune responses

Association of soluble T cell immunoglobulin domain and mucin-3 (sTIM-3) and mac-2 binding protein glycosylation isomer (M2BPGi) in patients with autoimmune hepatitis.

BackgroundAutoimmune hepatitis (AIH) is a disorder of unknown etiology in which immune-mediated liver injury progress to cirrhosis or hepatocellular carcinoma (HCC). The aim of the present study was to determine whether circulating soluble TIM3 (sTIM3) is elevated in patients with AIH patients and whether sTIM-3 levels are associated with clinical parameters of AIH.MethodsWe enrolled 123 Japanese patients with AIH who were identified from the National Hospital Organization-AIH-liver-network database, as well as 32 patients with chronic hepatitis C (CHC), 30 patients with primary biliary cholangitis (PBC) and healthy control subjects. Serum sTIM-3 concentrations were quantified by ELISA.ResultsSerum levels of sTIM-3 were significantly higher in AIH patients (median 4865 pg/ml; [interquartile range (IQR); 3122-7471]) compared to those in CHC (1026 pg/ml [IQR: 806-1283] pConclusionsCirculating sTIM-3 levels were elevated in AIH patients and are associated with AIH disease activity and AIH-related liver damage. These findings indicate that serum sTIM-3 correlated with disease status of AIH and could be useful biomarkers to detect autoimmune-mediated liver injury. Our data suggest a possible link between the TIM-3/GAL-9 pathway and AIH severity or phenotype, and further investigations of the TIM-3 pathway and AIH pathophysiology is warranted