Immunological expression of gangliosides in multiple sclerosis and in a demyelinating model disease in rabbits

Novel Molecular Mechanisms of Gangliosides in the Nervous System Elucidated by Genetic Engineering

Acidic glycosphingolipids, i.e., gangliosides, are predominantly and consistently expressed in nervous tissues of vertebrates at high levels. Therefore, they are considered to be involved in the development and function of nervous systems. Recent studies involving genetic engineering of glycosyltransferase genes have revealed novel aspects of the roles of gangliosides in the regulation of nervous tissues. In this review, novel findings regarding ganglioside functions and their modes of action elucidated mainly by studies of gene knockout mice are summarized. In particular, the roles of gangliosides in the regulation of lipid rafts to maintain the integrity of nervous systems are reported with a focus on the roles in the regulation of neuro-inflammation and neurodegeneration via complement systems. In addition, recent advances in studies of congenital neurological disorders due to genetic mutations of ganglioside synthase genes and also in the techniques for the analysis of ganglioside functions are introduced.

Gangliosides in Inflammation and Neurodegeneration

Gangliosides play roles in the regulation of cell signaling that are mediated via membrane microdomains, lipid rafts. In this review, functions of gangliosides in the maintenance of nervous systems with a focus on regulation of inflammation and neurodegeneration are addressed. During analyses of various ganglioside-lacking mutant mice, we demonstrated that nervous tissues exhibited inflammatory reactions and subsequent neurodegeneration. Among inflammation-related genes, factors of the complement system showed up-regulation with aging. Analyses of architectures and compositions of lipid rafts in nervous tissues from these mutant mice revealed that dysfunctions of complement regulatory proteins based on disrupted lipid rafts were main factors to induce the inflammatory reactions resulting in neurodegeneration. Ganglioside changes in development and senescence, and implication of them in the integrity of cell membranes and cellular phenotypes in physiological and pathological conditions including Alzheimer disease have been summarized. Novel directions to further analyze mechanisms for ganglioside functions in membrane microdomains have been also addressed.

Upregulation of group 1 CD1 antigen presenting molecules in guinea pigs with experimental autoimmune encephalomyelitis: an immunohistochemical study

In humans, group 1 CD1 glycoproteins present foreign and self lipid and glycolipid antigens to T-cells. Homologues of these molecules are not found in mice or rats but are present in guinea pigs (GPs). We examined CD1 and MHC class II expression in the central nervous system (CNS) of GPs sensitized for experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. In normal GPs and the uninflamed CNS, low-level MHC class II (MHC II) immunoreactivity occurred on vascular elements, meningeal macrophages and parenchymal microglial cells, whereas immunoreactivity for CD1 was absent. In the inflamed CNS, the majority of infiltrating cells were MHC II+ and microglia showed increased expression. CD1 immunoreactivity was detected on astrocytes and subsets of inflammatory cells Including B cells and macrophages. Minimal CD1 and MHC II co-expression was noted on inflammatory cells or glia. We conclude that group 1 CD1 molecules are strongly upregulated in the inflamed CNS on subsets of cells distinct from the majority of MHC II bearing cells. The expression of CD1 proteins in such lesions broadens the potential repertoire of antigens recognized at these sites and highlights the value of the GP as a model for studies of the relevance of CD1 molecules in host defense and autoimmune diseases.

Antiganglioside antibodies in patients with neuropsychiatric systemic lupus erythematosus

Antiganglioside antibodies (AGA) were determined in sera and cerebrospinal fluids (CSF) from 50 systemic lupus erythematosus (SLE) patients, and age-matched normal controls. The SLE patients were subdivided according to the type of clinical manifestation into two groups: neuropsychiatric SLE and active SLE without neuropsychiatric manifestation. The presence of these antibodies showed a significant correlation between IgG AGA in the CSF and IgM AGA in the serum and neuropsychiatric SLE. Fifteen patients had this antibody in the CSF without detectable levels in the serum. No correlation was seen between anticardiolipin antibodies in the serum of CSF and neuropsychiatric SLE. The present work suggests that antibodies against gangliosides may be a marker for neuropsychiatric SLE and that intrathecal antibody production can result in the development of this manifestation.

Multiple sclerosis: cell-mediated immunity to human brain gangliosides

Cell-mediated immunity (CMI) to myelin components has been implicated in Multiple Sclerosis (MS) pathogenesis: two targets were suggested, Myelin Basic Protein with controversial results and, more recently, gangliosides. In order to investigate their possible involvement, we have performed Leukocyte Migration inhibition (LMI) tests in the presence of human brain gangliosides. Thirty nine MS patients (twenty four being "definite", according to McDonald and Halliday's classification), twenty nine patients with Other Neurological Diseases (OND), thirty six patients with Inflammatory diseases (ID) and forty healthy controls were tested. MS patients were divided into two groups, depending on the clinical stage of the disease. The mean migration inhibition percentage of the MS-attack group was found to be significantly different from the four others (p less than 0.01) (24.4 +/- 16.2 versus 10.9 +/- 8.5 in MS without attack, 4.4 +/- 12.9 in OND, 3.9 +/- 13.9 in ID and 11.1 +/- 12.1 in healthy subjects). LMI to gangliosides is therefore significantly increased during the attack stage in MS. These results support the notion of a Delayed Type Hypersensitivity to these glycolipids during the active stage of the disease.