Sulfoglucuronyl Paragloboside Research Articles

Antibodies to myelin‐associated glycoprotein (anti‐Mag) in IgM amyloidosis may influence expression of neuropathy in rare patients

We have examined whether antibodies to myelin-associated glycoprotein (anti-MAG) influence neuropathy occurrence and phenotype in primary (AL IgM) amyloidosis. Anti-MAG and the cross-reacted sulfoglucuronyl paragloboside antibodies (SGPG) were studied in 46 patients with IgM amyloidosis (21 with polyneuropathy), and 21 matched IgM MGUS (monoclonal gammopathies of undetermined significance) controls without neuropathy. We assessed the occurrence, phenotype of neuropathy, and attributes of nerve conduction and their relation to antibody activity. Twenty of 46 patients with IgM amyloidosis (7 with and 13 without polyneuropathy) had elevation of anti-MAG or SGPG by enzyme-linked immunosorbent assay (ELISA). Two of the polyneuropathy patients with IgM amyloidosis had antibodies to MAG based on Western blot (WB) positivity. One of these patients, with the highest anti-MAG titer, had a painful sensory ataxia, with prominent demyelination, and amyloid deposition in sural nerve. The other anti-MAG WB-positive amyloid patient had an axonal neuropathy and dysautonomia. Low levels of anti-MAG antibodies were found in 12 of 21 IgM MGUS controls without neuropathy (mean follow-up, 11 years). We conclude that finding serum anti-MAG antibodies does not exclude the diagnosis of primary amyloidosis. They do not appear to affect the occurrence or expression of polyneuropathy, except possibly in occasional cases with WB positivity.

Induction of experimental ataxic sensory neuronopathy in cats by immunization with purified SGPG

IgM paraproteins in about 50% of the patients with neuropathy associated with IgM gammopathy react with carbohydrate moieties in myelin-associated glycoprotein (MAG) and in sulfated glucuronic glycolipids (SGGLs) in human peripheral nerves. However, the role of anti-MAG/SGGL antibodies in the pathogenesis of neuropathy remains unclear. In order to induce an animal model of neuropathy associated with anti-MAG/SGGL antibodies, cats were immunized with sulfoglucuronyl paragloboside (SGPG). All four cats immunized with SGPG developed clinical signs of sensory neuronopathy within 11 months after initial immunization, characterized by unsteadiness, falling, hind limb weakness and ataxia. In two cats the ataxia and hind limb paralysis were so severe that the animals had to be euthanized. Pathological examination revealed sensory ganglionitis with inflammatory infiltrates in the dorsal root ganglia. No overt signs of pathology were noted in the examined roots or nerves. High titer anti-SGPG/MAG antibodies were detected in all 4 cats immunized with SGPG but not in 3 control cats. Our data demonstrate that immunization of cats with SGPG induced anti-SGPG antibodies and sensory neuronopathy clinically resembling the sensory ataxia of patients with monoclonal IgM anti-MAG/SGPG antibodies. This study suggests that these anti-MAG/SGPG antibodies play a role in the pathogenesis of this neuropathy.

Severe cranial nerve involvement in a patient with monoclonal anti-MAG/SGPG IgM antibody and localized hard palate amyloidosis

We report a patient with severe cranial polyneuropathy as well as sensory limb neuropathy. Biclonal serum IgM-κ/IgM-λ gammopathy was found and serum anti-myelin-associated glycoprotein (MAG)/sulfoglucuronyl paragloboside (SGPG) IgM antibody was also detected. Immunofluorescence analysis of a sural nerve biopsy specimen revealed binding of IgM and λ-light chain on myelin sheaths. No amyloid deposition was detected in biopsied tissues except for the hard palate, suggesting that the amyloidosis was of the localized type and had no relation to the pathogenesis of cranial neuropathy. Our observations indicate that the anti-MAG/SGPG IgM antibody may be responsible for this patient's cranial polyneuropathy, which is a rare manifestation in anti-MAG/SGPG-associated neuropathy.

Neuropathy and IgM M-proteins: prognostic value of antibodies to MAG, SGPG, and sulfatide.

In polyneuropathy associated with immunoglobulin M (IgM) monoclonal gammopathy, antibodies to myelin-associated glycoprotein (MAG), sulfoglucuronyl paragloboside (SGPG), and sulfatide have been associated with specific clinical and electrophysiologic features. However, it is not known whether the results of antibody tests provide additional information for the individual patient (and the neurologist) in terms of future neurologic deficit or outcome. To study the independent contribution of potential prognostic factors to the prediction of outcome of neuropathy associated with IgM monoclonal gammopathy. In accordance with the chronology in which prognostic factors are available in clinical practice, the association between prognostic factors and outcome was evaluated by univariate and multivariate logistic regression analysis in 65 patients with polyneuropathy and IgM monoclonal gammopathy. In univariate analysis, the initial symptoms, the IgM light chain type, electrophysiologic and pathologic studies, the presence of sural nerve IgM deposition, and anti-MAG or anti-SGPG antibodies were significantly associated with outcome. However, multivariate analysis showed that only initial symptoms and electrophysiologic studies are independent prognostic factors: initial sensory symptoms of the feet are prognostic for a slowly progressive disease course and less disability at 4 years, and evidence for demyelination on electrophysiologic examination is prognostic for development of weakness and symptoms of the upper extremities at 4 years. Addition of anti-MAG or anti-SGPG antibody tests did not yield any additional prediction of outcome. These results indicate that in clinical practice, antibody tests in polyneuropathy associated with IgM monoclonal gammopathy do not have a prognostic value in terms of future neurologic deficit or outcome.

Glycosphingolipid composition of a new immortalized human cerebromicrovascular endothelial cell line.

Previous studies have demonstrated the involvement of glycosphingolipid (GSL) antigens in the pathogenesis of immune-mediated neurological disorders such as peripheral neuropathies and multiple sclerosis. To study the role of the blood-brain barrier (BBB) in these disorders, we used a new human cerebromicrovascular endothelial cell (HCEC) line that has been immortalized through transfection with the plasmid pSV3-neo encoding for the SV40 large T-antigen and the neomycin gene. The immortalized HCEC (SV-HCEC) exhibited accelerated proliferation rates but maintained phenotypic properties of early-passage control cells. Therefore, this human cell line may serve as a useful in vitro model for studying the properties of the human BBB. We first investigated the GSL composition of cultured SV-HCECs. The major gangliosides were GM3 (62% of total gangliosides), GM2 (18%), GM1 (3%), and GD1a (15%). The major neutral GSLs were glucosylceramide (15% of the total neutral glycolipids), lactosylceramide (36%), globotriaosylceramide (3%), and globoside (43%). Trace amounts of paragloboside, lactosaminyl paragloboside, and sulfoglucuronyl paragloboside could also be detected by TLC-immunostaining. These results provide the basis for further investigations of the expression of these cell surface antigens in cultured SV-HCECs on activation with inflammatory cytokines such as interleukin-1beta, tumor necrosis factor-alpha, and interferon-gamma, which have been implicated as playing an important role in the pathogenesis of many nervous system disorders.

Elevation of serum soluble E-selectin and antisulfoglucuronyl paragloboside antibodies in amyotrophic lateral sclerosis

Immunological abnormality is often found in amyotrophic lateral sclerosis (ALS). Antibodies to sulfoglucuronyl paragloboside (SGPG) were reported in ALS, although the pathogenetic significance of the antibodies is still unknown. We have already demonstrated that SGPG, a unique glycolipid, is present in both peripheral nerve and vascular endothelial cells. To investigate whether serum anti-SGPG antibodies would participate in activation and/or injury of endothelial cells in ALS, we examined serum anti-SGPG antibodies in association with serum soluble E- and P-selectins, which are markers of activated endothelial cells, in 25 patients with ALS and 14 age-matched patients with other neurological diseases (ONDs) using the microtiter-ELISA method. Seven out of 25 ALS patients had anti-SGPG antibodies. Levels of sE-selectin were significantly higher in patients with ALS (48.5 ± 23.4 ng/ml) compared with ONDs (24.0 ± 11.8 ng/ml) (P < 0.005). Four out of seven ALS patients with anti-SGPG antibodies had concomitantly high sE-selectin levels. The mean sE-selectin levels were higher in patients with anti-SGPG antibodies (61.9 ± 25.2 ng/ml) than in those without anti-SGPG antibodies (43.3 ± 21.1 ng/ml). Anti-SGPG antibodies may take part in the activation and/or injury of endothelial cells. The increased expression of E-selectin may be related to an immunological process in some ALS patients.

Elevation of serum soluble E-selectin and antisulfoglucuronyl paragloboside antibodies in amyotrophic lateral sclerosis.

Immunological abnormality is often found in amyotrophic lateral sclerosis (ALS). Antibodies to sulfoglucuronyl paragloboside (SGPG) were reported in ALS, although the pathogenetic significance of the antibodies is still unknown. We have already demonstrated that SGPG, a unique glycolipid, is present in both peripheral nerve and vascular endothelial cells. To investigate whether serum anti-SGPG antibodies would participate in activation and/or injury of endothelial cells in ALS, we examined serum anti-SGPG antibodies in association with serum soluble E- and P-selectins, which are markers of activated endothelial cells, in 25 patients with ALS and 14 age-matched patients with other neurological diseases (ONDs) using the microtiter-ELISA method. Seven out of 25 ALS patients had anti-SGPG antibodies. Levels of sE-selectin were significantly higher in patients with ALS (48.5 +/- 23.4 ng/ml) compared with ONDs (24.0 +/- 11.8 ng/ml) (P < 0.005). Four out of seven ALS patients with anti-SGPG antibodies had concomitantly high sE-selectin levels. The mean sE-selectin levels were higher in patients with anti-SGPG antibodies (61.9 +/- 25.2 ng/ml) than in those without anti-SGPG antibodies (43.3 +/- 21.1 ng/ml). Anti-SGPG antibodies may take part in the activation and/or injury of endothelial cells. The increased expression of E-selectin may be related to an immunological process in some ALS patients.

内耳障害患者のグルクロン酸含有特異酸性糖脂質抗体に関する研究

Glycosphingolipids are molecules present on the surface of normal nerve cells and are considered antigenic. Recent studies have isolated these antigens in vestibular neuroepithelia, cochleovestibular nerves and the endolymphatic sac. The purpose of this study was to determine the presence of antibodies against the glycosphingolipid antigen, sulfoglucuronyl paragloboside (SGPG), in the sera of patients suspected of autoimmune inner ear disease. The sera of a total 41 patients, including cases of progressive sensorineural hearing loss (PSNHL) (n= 19), sudden deafness (SD) (n = 8), Ménière's disease (n = 9), mumps hearing loss (n = 5), were tested for antibodies against the SGPG antigen. Antibody titers were determined by the microtiter ELISA method. Antibody titers were elevated in 36.8% of patients with PSNHL,25.0% of sudden deafness patients, while no elevation was observed in Mniere' s disease patients and mumps patients. Because SGPG antigens have been recently isolated in the inner ear, especially in the cochleovestibular nerve, these structures can potentially become targets for anti-SGPG antibodies.

Anti-MAG and anti-SGPG antibodies in neuropathy

We compared the binding of human antibodies from patients with neuropathy to the myelin-associated glycoprotein (MAG), to its cross-reactive glycolipid sulfoglucuronyl paragloboside (SGPG), and to sections of peripheral nerve. Titers were correlated with the clinical presentation and results of electrophysiological and pathological studies. Most patients had a predominantly sensory or sensorimotor demyelinating neuropathy and highly elevated antibodies to both MAG and SGPG, but 2 had highly elevated antibodies to MAG alone, and 1 to SGPG alone. Two patients had predominantly motor neuropathy and highly elevated antibodies to SGPG which reacted with MAG by Western blot but not by enzyme-linked immunosorbent assay. One patient had amyotrophic lateral sclerosis and antibodies to SGPG but not to MAG. These studies indicate that the neuropathic syndrome associated with anti-MAG or -SGPG antibodies are more heterogeneous than previously suspected, and that although most of the antibodies react with both MAG and SGPG, some may react with MAG or SGPG alone.

Multireactive pattern of serum autoantibodies in asymptomatic individuals with immunoglobulin A deficiency

Selective immunoglobulin A (IgA) deficiency (sIgAD) is associated with certain autoimmune states. Increased production of autoantibodies and eventual development of overt autoimmune disease are related in part to genetic and environmental factors as well as to the immune deficiency. We surveyed serum specimens from 60 healthy subjects with sIgAD for the presence of 21 different autoantibodies by enzyme-linked immunosorbent assays. The frequencies of 16 autoantibodies were higher in sIgAD patients than in normal healthy controls. Autoantibodies to Jo-1 (28%), cardiolipin (21%), phosphatidylserine (20%), Sm (15%), asialo-GM1 (21%), sulfatide (32%), sulfoglucuronyl paragloboside (11%), and collagen type I (10%) were detected at high frequencies in comparison to those of normal healthy controls. Many of the serum samples were multireactive (i.e., exhibited binding to more than two autoantigens). Forty percent (24 of 60) of sIgAD serum samples reacted against six or more autoantigens; 10% (6 of 60) of sIgAD serum samples were not reactive with any of the 21 autoantigens. Three percent (7 of 209) of consecutive serum samples submitted for autoimmune antibody analysis that were positive for autoantibodies were from patients with IgA deficiency. Our finding of an increased frequency of autoantibodies in sIgAD patients supports the notion of polyclonal stimulation by repeated environmental stimuli as an etiologic mechanism. Alternatively, the increased frequency may be caused by a dysregulation of the immune response in such individuals. The mere detection of autoantibodies cannot predict whether a subject with sIgAD will develop an autoimmune disease or determine which specific disease will emerge.

Rapid Communication: GM3 Regulates Protein Kinase Systems in Cultured Brain Microvascular Endothelial Cells

The barrier function of endothelial cells is known to be positively regulated by protein kinase A (PKA) and negatively regulated by protein kinase C (PKC). We found that exogenously administered GM3(NeuAc) promoted PKA activity in cultured brain microvascular endothelial cells (BMECs). Other glycolipids, including GM1, sulfoglucuronyl paragloboside, and GM3(NeuGc), did not have any effect on the PKA activity of BMECs. PC12 cells did not respond to exogenously applied GM3(NeuAc). GM3(NeuAc) also suppressed the PKC activity of BMECs. Thus, GM3(NeuAc) may function as a modulator of blood-brain barrier function via the two different kinase systems.

Antibodies to sulfated glycolipids in Guillain-Barré syndrome

Sera from 53 patients with acute Guillain-Barré syndrome (GBS), 15 patients with chronic inflammatory demyelinating polyneuropathy (CIDP), 13 patients with other neurological diseases (OND) and 31 healthy controls were tested for IgM and IgG antibodies to sulfoglucuronyl paragloboside (SGPG) and sulfatide by both an ELISA and a thin-layer chromatogram-overlay technique. Although the mean levels of anti-SGPG or anti-sulfatide antibodies in GBS patients were not elevated compared to controls, the occurrence of anti-SGPG antibodies was more frequent in GBS patients than in controls ( P < 0.02). Acute GBS patients with antibodies to SGPG or sulfatide were clinically indistinguishable from other GBS patients. Our data suggest that elevated levels of antibodies to SGPG could be important in the pathogenesis of neuropathy in some GBS patients.

Induction of demyelination by intraneural injection of antibodies against sulfoglucuronyl paragloboside

Sulfoglucuronyl glycolipids (SGGLs) carry the glucuronyl 3-sulfate (HNK-1) epitope which is recognized by monoclonal IgM paraproteins from patients with demyelinating polyneuropathy. We report that intraneural injections of rat anti-SGGL antibodies induce demyelination in rat sciatic nerve, along with mild to moderate clinical symptoms. Morphologically, vesiculation and loosening of the myelin sheath were observed 3 h postinjection, followed by extensive demyelination and macrophage infiltration after 4 days. Since the antiSGGL antibodies showed no cross-reactivity with other components in rat sciatic nerve, these results indicate that SGGLs alone can serve as the target antigens in demyelinating neuropathy.

Glycosphingolipids in the cerebrospinal fluid of patients with multiple sclerosis

Glycosphingolipids in cerebrospinal fluid (CSF) of individual patients with multiple sclerosis (MS) were analyzed using a glycolipid-overlay technique. The ganglioside composition of CSF of non-MS patients was characterized by an abundance of polysialo species, including GT1b and GQ1b. This pattern is completely different from that of human white or gray matter, in which mono- and disialogangliosides predominate. Increased levels of GM1, either associated with or without increases of other gangliosides, such as GD1a, were observed in 16% of the patients with MS (6 of 37 cases: 1 of 15 progressive progressive stage, 4 of 16 progressive stationary stage, and 1 of 6 relapsing stage). The concentration of GD3 was increased in 23% (3 of 13 cases), whereas 1 of 13 cases (8%) showed a dramatic increase of sulfoglucuronyl paragloboside (SGPG) associated with a high level of GD3. These changes may reflect the cellular changes associated with the known pathological lesions in MS, which are characterized by demyelination, gliosis, and/or remyelination with oligodendrocytic proliferation.

Autoimmune mechanisms in peripheral neuropathies

In certain patients with demyelinating neuropathy and plasma cell dyscrasia, there are IgM monoclonal antibodies that recognize a carbohydrate epitope shared by myelin-associated glycoprotein (MAG) and at least two acidic glycolipids in the peripheral nervous system (PNS). The structures of the two acidic lipids have been elucidated as a new class of glycosphingolipids, termed sulfoglucuronyl glycolipids (SGGLs). SGGLs have been demonstrated to be present in myelin, axolemma, and other glia-related membranes in PNS of several animal species, as well as in human dorsal root ganglia and sympathetic ganglia. In rabbits sensitized with sulfoglucuronyl paragloboside (SGPG), a major SGGL in PNS, antibodies developed with reactivities toward SGPG and MAG. The animals also showed moderate weakness, a slowed nerve conduction velocity, and evidence of conduction block. Recently we also found SGPG in rat brain microvessels. This finding supports our hypothesis that autoantibodies may first interact with endothelial cell-bound antigens and that this might change the permeability of the blood-brain or blood-nerve barrier to permit the entry of these autoantibodies into the nervous system. Our data are consistent with the concept that an autoimmune response against the sulfoglucuronyl residue may participate in the pathogenesis of immune-mediated neuropathy.

Differences in lipid composition between isolated growth cones from the forebrain and those from the brainstem in the fetal rat

The lipid composition of nerve growth cone membranes isolated from rat fetal forebrain or brainstem by the sucrose density gradient method was analyzed biochemically and immunochemically. In the forebrain, growth cone membrane (GCM) contained lower levels of gangliosides than those from other heavier fractions, but it was not the case in the fetal brainstem at the same developmental stage. The distinctive features in the ganglioside composition of GCM are the predominance of GD3 and the presence of c-series gangliosides that are due to fetal expression in mammals. A unique acidic glycolipid, sulfoglucuronylparagloboside (SGPG), which is not present in adult brains, was first detected in both forebrain and brainstem GCM. Including such minor species, the ganglioside composition in forebrain or brainstem GCM was almost identical to other membrane fractions from the forebrain or brainstem. The compositional ratios of the major lipid classes in membranes, cholesterol and phospholipids, seemed to be common to forebrain GCM and brainstem GCM, as indicated by the identical values of phospholipid-to-protein (PL/Pr), cholesterol-to-protein (Ch/Pr), and cholesterol-to-phospholipid (Ch/PL) ratios for both. This study has revealed that GCM isolated from forebrain which is supposed to be at an earlier stage of neuronal differentiation than brainstem has less amounts of total gangliosides, high proportion of GD3 to GD1a and enriched c-series gangliosides as compared to brainstem GCM.