a b s t r a c tElevated amyloid-b peptide (Ab) in brain contributes to Alzheimer's disease (AD) pathogenesis. We demonstrated the presence of exosome-associated Ab in the cerebrospinal fluid (CSF) of cynomolgus monkeys and APP transgenic mice. The levels of exosome-associated Ab notably decreased in the CSF of aging animals. We also determined that neuronal exosomes, but not glial exosomes, had abundant glycosphingolipids and could capture Ab. Infusion of neuronal exosomes into brains of APP transgenic mice decreased Ab and amyloid depositions, similarly to what reported previously on neuroblastoma-derived exosomes. These findings highlight the role of neuronal exosomes in Ab clearance, and suggest that their downregulation might relate to Ab accumulation and, ultimately, the development of AD pathology.

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Background: To study the effects of a pre-germinated brown rice diet (PR) on diabetic neuropathy in streptozotocin (STZ)-induced diabetic rats.

A protocol for negative ion nanoelectrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (-)nanoESI-FTICR MS, investigation of complex biological mixtures consisting of sialylated or sulfated glycosphingolipids (GSL) expressing high heterogeneity in the ceramide portion is described. Different instrumental and solvent conditions were explored and optimized to promote efficient ionization, reduce the in-source fragmentation and consequently enhance the detection of intact molecular species from complex mixtures. Using the novel optimized (-)nanoESI-FTICR MS protocol, a reliable and detailed compositional fingerprint of the polysialylated ganglioside mixture isolated from human brain was obtained. Sustained off-resonance irradiation collision-induced dissociation mass spectrometry (SORI-CID MS2) was introduced for the first time for structural elucidation of polysialylated gangliosides. Under well-defined conditions, an informative fragmentation pattern of the trisialylated ganglioside GT1 was obtained. The compositional mapping of a complex mixture of sulfated glucuronic acid containing neolacto-series GSLs extracted from bovine Cauda equina provided hard evidence upon previously described components and new structures not identified before by any other analytical method. Negative ion nanoESI-FTICR MS at 9.4 T is shown here to represent a valuable method in glycolipidomics, allowing a high resolution and mass accuracy detection of major and minor GSL glycoforms and identification of known and novel biologically relevant structures.

The accumulation of amyloid-β protein (Aβ) in brain is linked to the early pathogenesis of Alzheimer’s disease (AD). We previously reported that neuron-derived exosomes promote Aβ clearance in the brains of amyloid precursor protein transgenic mice and that exosome production is modulated by ceramide metabolism. Here, we demonstrate that plant ceramides derived from Amorphophallus konjac, as well as animal-derived ceramides, enhanced production of extracellular vesicles (EVs) in neuronal cultures. Oral administration of plant glucosylceramide (GlcCer) to APP overexpressing mice markedly reduced Aβ levels and plaque burdens and improved cognition in a Y-maze learning task. Moreover, there were substantial increases in the neuronal marker NCAM-1, L1CAM, and Aβ in EVs isolated from serum and brain tissues of the GlcCer-treated AD model mice. Our data showing that plant ceramides prevent Aβ accumulation by promoting EVs-dependent Aβ clearance in vitro and in vivo provide evidence for a protective role of plant ceramides in AD. Plant ceramides might thus be used as functional food materials to ameliorate AD pathology.

Dietary sphingolipids such as glucosylceramide (GlcCer) are potential nutritional factors associated with prevention of metabolic syndrome. Our current understanding is that dietary GlcCer is degraded to ceramide and further metabolized to sphingoid bases in the intestine. However, ceramide is only found in trace amounts in food plants and thus is frequently taken as GlcCer in a health supplement. In the present study, we successfully prepared konjac ceramide (kCer) using endoglycoceramidase I (EGCase I). Konjac, a plant tuber, is an enriched source of GlcCer (kGlcCer), and has been commercialized as a dietary supplement to improve dry skin and itching that are caused by a deficiency of epidermal ceramide. Nerve growth factor (NGF) produced by skin cells is one of the itch factors in the stratum corneum of the skin. Semaphorin 3A (Sema 3A) has been known to inhibit NGF-induced neurite outgrowth of epidermal nerve fibers. It is well known that the itch sensation is regulated by the balance between NGF and Sema 3A. In the present study, while kGlcCer did not show an in vitro inhibitory effect on NGF-induced neurite outgrowth of PC12 cells, kCer was demonstrated to inhibit a remarkable neurite outgrowth. In addition, the effect of kCer was similar to that of Sema 3A in cell morphological changes and neurite retractions, but different from C2-Ceramide. kCer showed a Sema 3A-like action, causing CRMP2 phosphorylation, which results in a collapse of neurite growth cones. Thus, it is expected that kCer is an advanced konjac ceramide material that may have neurite outgrowth-specific action to relieve uncontrolled and serious itching, in particular, from atopic eczema.

Recently we have reported cases of demyelinating inflammatory neuropathy showing elevated titers of anti-GD3 antibodies, which occurs rarely in Guillain-Barré syndrome. To examine the correlation between the anti-GD3 antibody titer and Campylobacter jejuni infection, we sensitized female Lewis rats with lipopolysaccharides (LPSs) from serotype HS19 of C. jejuni and examined changes in nerve conduction velocity and nerve conduction block (P/D ratio). After 16 weeks of sensitization, animals revealed decreases of nerve conduction velocity and conduction block (P/D ratio) and high titer of anti-GD3 antibodies. These anti-GD3 antibodies also blocked transmission in neuromuscular junctions of spinal cord-muscle cells cocultures. The GD3 epitope was verified to be located on the Schwann cell surface and nodes of Ranvier in rat sciatic nerve. To determine the target epitope for GD3 antibodies in causing nerve dysfunction, the LPS fraction containing the GD3 epitope was purified from the total LPS by using an anti-GD3 monoclonal antibody-immobilized affinity column. Subsequently, chemical analysis of the oligosaccharide portion was performed and confirmed the presence of a GD3-like epitope as having the following tetrasaccharide structure: NeuAcα2-8NeuAc2-3Galβ1-4Hep. Our data thus support the possibility of a contribution of GD3 mimicry as a potential pathogenic mechanism of peripheral nerve dysfunction. Keywordsganglioside; Guillain-Barré; syndrome; anti-ganglioside antibody; GD3; Campylobacter jejuni; LPS Guillain-Barré syndrome (GBS) is an acute immune-mediated peripheral neuropathy consisting of acute inflammatory demyelinating polyneuropathy (AIDP), acute motor neuropathy (AMAN), and related disorders. Anti-GM1 antibodies are often detected in patients with AIDP and AMAN (Kornberg et al., 1994;Arasaki et al., 1998;Hiraga et al., 2005). Many investigators have reported the association between an antecedent Campylobacter jejuni (C. jejuni) infection and subsequent development of GBS. The lipopolysaccharides (LPSs) of a certain serotype of C. jejuni have been shown to possess carbohydrate epitopes similar to *Correspondence to: Dr. Robert K. Yu, Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912-2697. ryu@mcg.edu. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript gangliosides, which may serve as the putative pathogenic triggers for subsequent GBS onset. Thus, these disorders may develop as a result of C. jejuni infection. In addition to anti-GQ1b Abs, anti-GD3 Abs have been detected in the Miller Fisher variant of GBS (Chiba et al., 1992;Carpo et al., 1998;Susuki et al., 2001;Willison and Yuki, 2002;Willison et al., 2004).Recently we have reported cases of AIDP and chronic inflammatory demyelinating polyneuropathy (CIDP) showing high elevations of anti-GD3 Abs, which rarely occurs in GBS (Usuki et al., 2005). The question then arises of the origin of the antiglycolipid (anti-GSL) Abs in GBS, in particular, the mechanism of el...

Previous studies from our laboratory indicated that pre-germinated brown rice (PR) contained certain unknown bioactive lipids that activated two enzymes related to diabetes: Na 1 /K 1 ATPase and homocysteine-thiolactonase. In this paper, we report on the isolation and structural characterization of the activator lipids from PR bran as acylated steryl glucosides (ASGs). The activator lipid was isolated by silica gel column chromatography, and its chemical structure was determined by NMR, GC-MS, and tandem mass spectrometry. We demonstrated that the bioactive component consists of a mixture of acylated steryl b-glucosides. #8-cholesterol and 2-hydroxyl stearic acid were identified as constituents of ASGs. The steryl glucosides (SGs) subsequent to alkaline hydrolysis lost this enzyme activator activity. Soybean-derived ASGs were not active. This activity may be quite peculiar to PR-derived ASGs. Our findings suggest that the molecular species of ASG may play an important contributing role in the anti-diabetic properties of a PR diet.-Usuki, S., T. Ariga, S. Dasgupta, T.