Seigo Usuki

Ganglioside Molecular Mimicry and Its Pathological Roles in Guillain-Barré Syndrome and Related Diseases

Guillain-Barre syndrome (GBS) is the most frequent cause of acute flaccid paralysis in humans, occurring with an annual incidence of 1 to 2 cases per 100,000 people. In recent years, studies have shed new light on a number of disease aspects that have enhanced the understanding of the pathogenic

Effect of pre-germinated brown rice intake on diabetic neuropathy in streptozotocin-induced diabetic rats

BackgroundTo study the effects of a pre-germinated brown rice diet (PR) on diabetic neuropathy in streptozotocin (STZ)-induced diabetic rats.MethodsThe effects of a PR diet on diabetic neuropathy in STZ-induced diabetic rats were evaluated and compared with those fed brown rice (BR) or white rice (WR) diets with respect to the following parameters: blood-glucose level, motor-nerve conduction velocity (NCV), sciatic-nerve Na+/K+-ATPase activity, and serum homocysteine-thiolactonase (HTase) activity.ResultsCompared with diabetic rats fed BR or WR diets, those fed a PR diet demonstrated significantly lower blood-glucose levels (p < 0.001), improved NCV (1.2- and 1.3-fold higher, respectively), and increased Na+/K+-ATPase activity (1.6- and 1.7-fold higher, respectively). The PR diet was also able to normalize decreased serum homocysteine levels normally seen in diabetic rats. The increased Na+/K+-ATPase activity observed in rats fed PR diets was associated with elevations in HTase activity (r = 0.913, p < 0.001). The in vitro effect of the total lipid extract from PR bran (TLp) on the Na+/K+-ATPase and HTase activity was also examined. Incubation of homocysteine thiolactone (HT) with low-density lipoprotein (LDL) in vitro resulted in generation of HT-modified LDL, which possessed high potency to inhibit Na+/K+-ATPase activity in the sciatic nerve membrane. The inhibitory effect of HT-modified LDL on Na+/K+-ATPase activity disappeared when TLp was added to the incubation mixture. Furthermore, TLp directly activated the HTase associated with high-density lipoprotein (HDL).ConclusionPR treatment shows efficacy for protecting diabetic deterioration and for improving physiological parameters of diabetic neuropathy in rats, as compared with a BR or WR diet. This effect may be induced by a mechanism whereby PR intake mitigates diabetic neuropathy by one or more factors in the total lipid fraction. The active lipid fraction is able to protect the Na+/K+-ATPase of the sciatic-nerve membrane from the toxicity of HT-modified LDL and to directly activate the HTase of HDL.

Molecular mimicry : Sensitization of lewis rats with Campylobacter jejuni lipopolysaccharides induces formation of antibody toward GD3 ganglioside

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.

Effect of rabbit anti-asialo-GM1 (GA1) polyclonal antibodies on neuromuscular transmission and acetylcholine-induced action potentials: Neurophysiological and immunohistochemical studies

We produced anti–asialo-GM1 (GA1) polyclonal antibodies by sensitizing New Zealand rabbits with GA1 and investigated the epitopes and pathogenic role of anti-GA1 antibodies that appeared in serum. The serum blocked neuromuscular transmission, but not acetylcholine (ACh)-induced potentials, in muscle–spinal cord cocultured cells. The effect was complement independent. The antibodies inhibited voltage-gated Ca2+ channel (VGCC). The epitopes recognized by the antibodies were located in the outer membrane of Schwann cells and motor axons of Wistar rat ventral roots and on motor axons extended from spinal cord to muscle cells in muscle–spinal cocultured cells. The ACh-induced potential was not reduced by the addition of sera, suggesting the blockade is presynaptic. Thus, anti-GA1 antibodies may block neuromuscular transmission by suppressing VGCC on axonal terminals of motor nerves.

AIDP and CIDP having specific antibodies to the carbohydrate epitope (–NeuAcα2–8NeuAcα2–3Galβ1–4Glc–) of gangliosides

Anti-ganglioside antibodies were investigated in plasma exchange solutions (PEs) from two patients with acute and chronic inflammatory demyelinating neuropathies (AIDP and CIDP). Both cases show markedly elevated antibody titers against the lacto-series gangliosides, GM3, GD3, and GT3. In the CIDP patient, the IgG antibody titer to GD3 was remarkably elevated (titer, 1:10,000), indicating maximal avidity to the tetrasaccharide epitope (-NeuAcalpha2-8NeuAcalpha2-3Galbeta1-4Glc-). There were also activities toward GM4 and GM2 with the affinity higher to GM4 than to GM2, indicating that the antibody activity was not highly specific. In contrast, the antibody activities in the AIDP patient showed similar avidity to GM3, GD3, and GT3. These two patients are very rare cases that have not previously encountered in GBS. The effects on co-cultured cells of rat spinal cord and muscle differed according to which PE was used. PE from the AIDP patient produced an inhibitory effect (reduction to 26.8%) on the spontaneous muscle action potential of the neuromuscular junction (NMJ), but the PE from the CIDP patient did not. Thus, in AIDP, the common epitope of GM3, GD3, or GT3 may be shared with certain antigens localized in the peripheral nervous system (PNS) and may participate in a component of conduction-related molecules in the NMJ. High titers of anti-GD3 antibody and the distortion of antibody recognition found in CIDP seem to have no immediate effect on electrophysiologic function in the PNS.

IGF-1 induction by acylated steryl β-glucosides found in a pre-germinated brown rice diet reduces oxidative stress in streptozotocin-induced diabetes

Background The pathology of diabetic neuropathy involves oxidative stress on pancreatic β-cells, and is related to decreased levels of Insulin-like growth factor 1 (IGF-1). Acylated steryl β-glucoside (PR-ASG) found in pre-germiated brown rice is a bioactive substance exhibiting properties that enhance activity of homocysteine-thiolactonase (HTase), reducing oxidative stress in diabetic neuropathy. The biological importance of PR-ASG in pancreatic β-cells remains unknown. Here we examined the effects of PR-ASG on IGF-1 and glucose metabolism in β-cells exposed to oxidative stress. Methodology/Principal Findings In the present study, a pre-germinated brown rice (PR)-diet was tested in streptozotocin (STZ)-induced diabetic rats. Compared with diabetic rats fed control diets, the PR-diet fed rats showed an improvement of serum metabolic and neurophysiological parameters. In addition, IGF-1 levels were found to be increased in the serum, liver, and pancreas of diabetic rats fed the PR-diet. The increased IGF-1 level in the pancreas led us to hypothesize that PR-ASG is protective for islet β-cells against the extensive injury of advanced or severe diabetes. Thus we examined PR-ASG to determine whether it showed anti-apoptotic, pro-proliferative effects on the insulin-secreting β-cells line, INS-1; and additionally, whether PR-ASG stimulated IGF-1 autocrine secretion/IGF-1-dependent glucose metabolism. We have demonstrated for the first time that PR-ASG increases IGF-1 production and secretion from pancreatic β-cells. Conclusion/Significance These findings suggest that PR-ASG may affect pancreatic β-cells through the activation of an IGF-1-dependent mechanism in the diabetic condition. Thus, intake of pre-germinated brown rice may have a beneficial effect in the treatment of diabetes, in particular diabetic neuropathy.

Novel anti-idiotype antibody therapy for lipooligosaccharide-induced experimental autoimmune neuritis: Use relevant to Guillain-Barré syndrome

Campylobacteriosis is a frequent antecedent event in Guillain‐Barré syndrome (GBS), inducing high‐titer serum antibodies for ganglioside antigens in the peripheral nervous system (PNS). Molecular mimicry between the lipooligosaccharide (LOS) component of Campylobacter jejuni and human peripheral nerve gangliosides is believed to play an important role in the pathogenesis of GBS. Conventional treatment strategies for patients with GBS include plasmapheresis, intravenous immunoglobulin (IVIG), and immunosuppression, which are invasive or relatively ineffective. In this study, we used our animal model of GBS, in which Lewis rats were immunized with GD3‐like LOS isolated from C.jejuni. The animals developed anti‐GD3 ganglioside antibodies and manifested neuromuscular dysfunction. To develop novel therapeutic strategies, we treated the animals by intraperitoneal administration of an anti‐GD3 antiidiotype monoclonal antibody (BEC2) that specifically interacts with the pathogenic antibody. The treated animals had a remarkable reduction of anti‐GD3 antibody titers and improvement of motor nerve functions. The results suggest that ganglioside mimics, such as antiidiotype antibodies, may be powerful reagents for therapeutic intervention in GBS by neutralizing specific pathogenic antiganglioside antibodies.

Pathological Roles of Ganglioside Mimicry in Guillain–Barré Syndrome and Related Neuropathies

Gangliosides, sialic acid-containing glycosphingolipids (GSLs), are a family of diverse, highly complex molecules localized primarily on the plasma membrane and particularly abundant in the nervous tissues of vertebrates. Research interest in gangliosides is not limited to their normal biological functions, such as neurotrophicity, cell–cell recognition and adhesion, cellular differentiation and growth, intercellular signaling, and trafficking and/or sorting [17, 19, 61, 62], or on the important constituents of cell surface microdomains or lipid rafts [18, 25, 44]. Research is also focused on the role of gangliosides in the pathogenic mechanisms of many immune-mediated neurological disorders, such as Guillain–Barre syndrome (GBS) [5, 57, 63]. For the putative pathogenic roles of gangliosides, accumulating evidence indicates that (a) gangliosides are localized in peripheral nerve system (PNS) myelin and axolemma, and degeneration of myelin and axons accounts for the loss of sensory and motor functions; (b) animal models of peripheral neuropathies can be established using certain pure gangliosides as the immunogens; and (c) the pathophysiological effects of the antibodies could be due to one or more of the following mechanisms: an antibody-mediated, complement-dependent process; a cell-mediated degenerating process; and a conduction block at the node of Ranvier.

Development of a novel therapy for Lipo-oligosaccharide-induced experimental neuritis: use of peptide glycomimics

J. Neurochem. (2010) 113, 351–362.

Glycosphingolipid Antigens in Neural Tumor Cell Lines and Anti-Glycosphingolipid Antibodies in Sera of Patients with Neural Tumors

To characterize biomarkers in neural tumors, we analyzed the acidic lipid fractions of 13 neural tumor cell lines using enzyme-linked immunoabsorbent assay (ELISA) and high-performance thin-layer chromatography (HPTLC) immunostaining. Sulfated glucuronosyl glycosphingolipids (SGGLs) are cell surface molecules that are endowed with the Human Natural Killer-1 (HNK-1) carbohydrate epitope. These glycosphingolipids (GSLs) were expressed in all cell lines with concentrations ranging from 210 to 330 ng per 2 × 106 cells. Sulfoglucuronosyl paragloboside (SGPG) was the prominent species with lesser amounts of sulfoglucuronosyl lactosaminyl paragloboside (SGLPG) in these tumor cell lines as assessed by quantitative HPTLC immunostaining. Among the gangliosides surveyed, GD3 and 9-O-acetylated GD3 (OAc-GD3) were expressed in all tumor cell lines. In contrast, fucosyl-GM1 was not found to restrict to small cell lung carcinoma cells. In addition, we have analyzed serum antibody titers against SGPG, GD3, and OAc-GD3 in patients with neural tumors by ELISA and HPTLC immunostaining. All sera had high titers of antibodies of the IgM isotype against SGPG (titers over 1:3,200), especially in tumors such as meningiomas, germinomas, orbital tumors, glioblastomas, medulloblastomas, and subependymomas. Serum in a patient with subependymomas also had a high anti-SGGL antibody titer of the IgG and IgA types (titers over 12,800). The titer of anti-GD3 antibody was also elevated in patients with subependymomas and medulloblastomas; the latter cases also had a high titer of antibody against OAc-GD3. Our data indicate that certain GSL antigens, especially SGGLs, GD3, and OAc-GD3, are expressed in neural tumor cells and may be considered as tumor-associated antigens that represent important biomarkers for neural tumors. Furthermore, antibody titers in sera of patients with these tumors may be of diagnostic value for monitoring the presence of tumor cells and tumor progression.