Structural elucidation of a capsular polysaccharide from a clinical isolate of Bacteroides vulgatus from a patient with Crohn's disease

Structural characterization of neutral and acidic glycolipids from Thermus thermophilus HB8

The structural characterization of glycolipids from Thermus thermophilus HB8 was performed in this study. Two neutral and one acidic glycolipids were extracted and purified by the modified TLC-blotting method, after which their chemical structures were determined by chemical composition analysis, mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy. The structure of one of the neutral glycolipids, NGL-A, was Galp(α1-6)GlcpNacyl(β1-2)Glcp(α1-)acyl(2)Gro, and the other, NGL-C, was Galf(β1-2)Galp(α1-6)GlcpNacyl(β1-2)Glcp(α1-)acyl(2)Gro. The structure of NGL-C was identical to that reported previously [Oshima, M. and Ariga, T. (1976) FEBS Lett. 64, 440]. Both neutral glycolipids shared a common structural unit found in the Thermus species. The acyl groups found in NGL-A and NGL-C, iso-type pentadecanoxy and heptadecanoxy fatty acid, were also the same as those found in this species. In contrast, the acidic glycolipid, AGL-B, possessed the structure of N-(((GlcpNAc(α1-)acyl(2)Gro)P-2)GroA)alkylamine. The alkyl group in AGL-B was an iso-type heptadecanyl, suggesting that the iso-type structure of the long alkyl chain is responsible for the thermal stability of the bacteria.

Therapeutic effects of roxithromycin in interleukin-10-deficient colitis

BACKGROUND

A limited number of therapeutic strategies are currently available to treat patients with inflammatory bowel disease (IBD). Interleukin-10 (IL-10)-deficient mice, well characterized as an experimental model of IBD, develop severe chronic colitis because of aberrant Th1 responses. Roxithromycin (RXM), a macrolide antibiotic, has received attention because it offers not only antibacterial but also immunosuppressive effects. We examined the immunosuppressive effect of RXM on the development of IBD.

METHODS

To test the efficacy of short-term administration of RXM, elder IL-10-deficient mice (16-20 weeks old) with established colitis were orally treated for 10 days with RXM (20 mg/kg per day). To test the long-term preventive effects of RXM, for 20 weeks young adult IL-10-deficient mice (4-5 weeks old) also were administered RXM orally (20 mg/kg per day).

RESULTS

The short-term treatment-oriented administration of RXM reduced the degree of inflammatory change and lowered serum amyloid A in IL-10-deficient mice with severe colitis. Mononuclear cells from the lamina propria of RXM-treated large intestines showed lower production of IFN-gamma than did those from diseased mice that were untreated. Long-term prevention-oriented administration of RXM suppressed the development of severe colitis and decreased production of IFN-gamma and IL-12. In addition to its expected immunosuppressive effect, RXM treatment also decreased the level of Bacteroides vulgatus, a Gram-negative anaerobe.

CONCLUSIONS

The anti-inflammatory changes observed in IL-10-deficient mice resulted from the efficacy of RXM as an immunosuppressant as well as from its efficacy as an antibiotic. According to our findings, RXM would seem to have significant potential as a preventive and/or therapeutic agent for IBD.

Polysaccharide biological response modifiers

Biological response modifiers (BRMs) are substances which augment immune response. BRMs can be cytokines which are produced endogenously in our body by immune cells or derivatives of bacteria, fungi, brown algae, Aloe vera and photosynthetic plants. Such exogeneous derivatives (exogeneous BRMs) can be nucleic acid (CpG), lipid (lipotechoic acid), protein or polysaccharide in nature. The receptors for these exogeneous BRMs are pattern recognition receptors. The binding of exogeneous BRMs to pattern recognition receptors triggers immune response. Exogenous BRMs have been reported to have anti-viral, anti-bacterial, anti-fungal, anti-parasitic, and anti-tumor activities. Among different exogeneous BRMs, polysaccharide BRMs have the widest occurrence in nature. Some polysaccharide BRMs have been tested for their therapeutic properties in human clinical trials. An overview of current understandings of polysaccharide BRMs is summarized in this review.

2JC,H Index: A Nondestructive NMR Method for Differentiation of Aldohexopyranosyl Residues

A new 2J(C,H) index method is described for identification of aldohexopyranose. This method is based on a fact that 2J(C,H) values reflect the stereochemistry for glycol connectivity. Based on the observed 2J(C,H) values for galactose, glucose, and mannose, 2J(C,H) profiles for other aldohexopyranoses are proposed. A combination of 2J(C,H) values was found to be useful for identification of aldohexopyranosyl residues in glycans. [structure: see text]

Structural study on lipid A and the O-specific polysaccharide of the lipopolysaccharide from a clinical isolate of Bacteroides vulgatus from a patient with Crohn's disease

Bacteroides vulgatus has been shown to be involved in the aggravation of colitis. Previously, we separated two potent virulence factors, capsular polysaccharide (CPS) and lipopolysaccharide (LPS), from a clinical isolate of B. vulgatus and characterized the structure of CPS. In this study, we elucidated the structures of O-antigen polysaccharide (OPS) and lipid A in the LPS. LPS was subjected to weak acid hydrolysis to produce the lipid A fraction and polysaccharide fraction. Lipid A was isolated by preparative TLC, and its structure determined by MS and NMR to be similar to that of Bacteroides fragilis except for the number of fatty acids. The polysaccharide fraction was subjected to gel-filtration chromatography to give an OPS-rich fraction. The structure of OPS was determined by chemical analysis and NMR spectroscopy to be a polysaccharide composed of the following repeating unit: [-->4)alpha-L-Rhap(1-->3)beta-D-Manp(1-->].