Detection of new anti-neutral glycosphingolipids antibodies and their effects on Trk neurotrophin receptors

Sphingolipid abnormalities in encephalomyeloradiculoneuropathy (EMRN) are associated with an anti-neutral glycolipid antibody

Accumulating evidence suggests that various sphingolipids and glycosphingolipids can act as mediators for inflammation or signaling molecules in the nervous system. In this article, we explore the molecular basis of a new neuroinflammatory disorder called encephalomyeloradiculoneuropathy (EMRN), which affects the brain, spinal cord, and peripheral nerves; in particular, we discuss whether glycolipid and sphingolipid dysmetabolism is present in patients with this disorder. This review will focus on the pathognomonic significance of sphingolipid and glycolipid dysmetabolism for the development of EMRN and the possible involvement of inflammation in the nervous system.

Comparison of relapsing polychondritis patients with and without central nervous system involvement: A retrospective study of 181 patients

The relapsing polychondritis (RP) patients with central nervous system (CNS) involvement were rare. We aimed to determine the clinical characteristics of RP patients with CNS involvement. The clinical data of 181 RP patients, hospitalized at Peking Union Medical College Hospital between December 2005 and February 2019, were collected. The patients were categorized into two subgroups: 25 RP patients with CNS involvement, and 156 RP patients without CNS involvement. The involvement of the ear was more frequent in RP patients with CNS involvement, compared with those of RP patients without CNS involvement (P < 0.01). After controlling sex and the admission age, logistic regression analysis revealed hypertension (odds ratio = 4.308, P = 0.006) and involvement of eye (odds ratio = 5.158, P = 0.001) and heart (odds ratio = 3.216, P = 0.025) were correlated with RP patients with CNS involvement, respectively. In addition, pulmonary infection (odds ratio = 0.170, P = 0.020), tracheal involvement (odds ratio = 0.073, P < 0.01), and involvement of laryngeal (odds ratio = 0.034, P = 0.001), costochondral joint (odds ratio = 0.311, P = 0.013), sternoclavicular joint (odds ratio = 0.163, P = 0.017) and manubriosternal joint (odds ratio = 0.171, P = 0.021) were associated with RP patients without CNS involvement, respectively. In contrast to RP patients without CNS involvement, the incidence of ear involvement was higher in RP patients with CNS involvement. After controlling the potential confounding factor sex and the admission age, hypertension and involvement of eye and heart were related with RP patients with CNS involvement, respectively.

GM1 Ganglioside Is A Key Factor in Maintaining the Mammalian Neuronal Functions Avoiding Neurodegeneration

Many species of ganglioside GM1, differing for the sialic acid and ceramide content, have been characterized and their physico-chemical properties have been studied in detail since 1963. Scientists were immediately attracted to the GM1 molecule and have carried on an ever-increasing number of studies to understand its binding properties and its neurotrophic and neuroprotective role. GM1 displays a well balanced amphiphilic behavior that allows to establish strong both hydrophobic and hydrophilic interactions. The peculiar structure of GM1 reduces the fluidity of the plasma membrane which implies a retention and enrichment of the ganglioside in specific membrane domains called lipid rafts. The dynamism of the GM1 oligosaccharide head allows it to assume different conformations and, in this way, to interact through hydrogen or ionic bonds with a wide range of membrane receptors as well as with extracellular ligands. After more than 60 years of studies, it is a milestone that GM1 is one of the main actors in determining the neuronal functions that allows humans to have an intellectual life. The progressive reduction of its biosynthesis along the lifespan is being considered as one of the causes underlying neuronal loss in aged people and severe neuronal decline in neurodegenerative diseases. In this review, we report on the main knowledge on ganglioside GM1, with an emphasis on the recent discoveries about its bioactive component.

Pleocytosis in a patient with relapsing polychondritis accompanied by meningoencephalitis: a case report

Background

Relapsing polychondritis (RP) is an uncommon immune-related disease with unknown causes. It is characterized by inflammation of cartilaginous or non-cartilaginous structures, such as the ears, nose, respiratory tract, eyes, and joints. Neurological involvement is rare in RP.

Case presentation

We report a case of pleocytosis in a 64-year-old man diagnosed as having RP with meningoencephalitis. The patient’s condition markedly improved following methylprednisolone treatment.

Conclusions

To our knowledge, this is the first report of recurrent pleocytosis in a patient with RP accompanied by meningoencephalitis. Steroid pulse therapy is effective in most cases, and early diagnosis is of importance.

Gangliosides in Membrane Organization

Since the structure of GM1 was elucidated 55years ago, researchers have been attracted by the sialylated glycans of gangliosides. Gangliosides head groups, protruding toward the extracellular space, significantly contribute to the cell glycocalyx; and in certain cells, such as neurons, are major determinants of the features of the cell surface. Expression of glycosyltransferases involved in the de novo biosynthesis of gangliosides is tightly regulated along cell differentiation and activation, and is regarded as the main metabolic mechanism responsible for the acquisition of cell-specific ganglioside patterns. The resulting sialooligosaccharides are characterized by a high degree of geometrical complexity and by highly dynamic properties, which seem to be functional for complex interactions with other molecules sitting on the same cellular membrane (cis-interactions) or soluble molecules present in the extracellular environment, or molecules associated with the surface of other cells (trans-interactions). There is no doubt that the multifaceted biological functions of gangliosides are largely dependent on oligosaccharide-mediated molecular interactions. However, gangliosides are amphipathic membrane lipids, and their chemicophysical, aggregational, and, consequently, biological properties are dictated by the properties of the monomers as a whole, which are not merely dependent on the structures of their polar head groups. In this chapter, we would like to focus on the peculiar chemicophysical features of gangliosides (in particular, those of the nervous system), that represent an important driving force determining the organization and properties of cellular membranes, and to emphasize the causal connections between altered ganglioside-dependent membrane organization and relevant pathological conditions.

Relapsing Polychondritis with Central Nervous System Involvement: Experience of Three Different Cases in a Single Center

Relapsing polychondritis (RP) is an autoimmune disorder characterized by inflammation in cartilaginous structures including the ears, noses, peripheral joints, and tracheobronchial tree. It rarely involves the central nervous system (CNS) but diagnosis of CNS complication of RP is challenging because it can present with varying clinical features. Herein we report 3 cases of relapsing polychondritis involving CNS with distinct manifestations and clinical courses. The first patient presented with rhombencephalitis resulting in brain edema and death. The second patient had acute cognitive dysfunction due to limbic encephalitis. He was treated with steroid pulse therapy and recovered without sequelae. The third patient suffered aseptic meningitis that presented as dementia, which was refractory to steroid and immune suppressive agents. We also reviewed literature on CNS complications of RP.

Lipid membrane domains in the brain

The brain is characterized by the presence of cell types with very different functional specialization, but with the common trait of a very high complexity of structures originated by their plasma membranes. Brain cells bear evident membrane polarization with the creation of different morphological and functional subcompartments, whose formation, stabilization and function require a very high level of lateral order within the membrane. In other words, the membrane specialization of brain cells implies the presence of distinct membrane domains. The brain is the organ with the highest enrichment in lipids like cholesterol, glycosphingolipids, and the most recently discovered brain membrane lipid, phosphatidylglucoside, whose collective behavior strongly favors segregation within the membrane leading to the formation of lipid-driven membrane domains. Lipid-driven membrane domains function as dynamic platforms for signal transduction, protein processing, and membrane turnover. Essential events involved in the development and in the maintenance of the functional integrity of the brain depend on the organization of lipid-driven membrane domains, and alterations in lipid homeostasis, leading to deranged lipid-driven membrane organization, are common in several major brain diseases. In this review, we summarize the forces behind the formation of lipid membrane domains and their biological roles in different brain cells. This article is part of a Special Issue entitled Brain Lipids.

Relapsing polychondritis with encephalitis: a case report and literature review

We herein report the case of a 39-year-old man who developed bilateral auricular chondritis, conjunctivitis, and central neurological symptoms. He was diagnosed with encephalitis associated with relapsing polychondritis (RP) based on the findings of an ear cartilage biopsy, cerebrospinal fluid examination and magnetic resonance imaging. Although oral prednisolone (60 mg/day) was administered, the initial steroid therapy did not improve his symptoms. In contrast, methylprednisolone (mPSL) pulse therapy followed by prednisolone gradually ameliorated his condition. There were no episodes of recurrence during the two-year follow-up period. A review of the literature revealed that meningoencephalitis and encephalitis are rare, but important, complications of RP responsive to mPSL pulse therapy.

Perivasculitic panencephalitis with relapsing polychondritis: an autopsy case report and review of previous cases

We herein report an autopsy case of relapsing polychondritis encephalitis coexisting with a Lewy body pathology and also review previous autopsy cases. A 59-year-old man exhibited a tremor of the right hand, small-steppage gait and bradykinesia. Five years later, he presented with relapsing auricular chondritis and scleritis and subsequently showed exacerbation of extrapyramidal symptoms. A histological examination revealed perivascular lymphocytic cuffing and infiltration in the small vessels, as well as loss of nerve cells and gliosis in the basal ganglia, insular gyrus and medial temporal lobe. The present case was characterized by perivasculitic panencephalitis and the coexistence of a Lewy body pathology, which may have augmented the patient's parkinsonism.

[Glycobiology and neurological disorders]

Many researchers now recognize the importance of glycobiological research achievements. Glycoside-containing substances such as proteins (glycoproteins) and lipids (glycosphingolipids) have been involved in many important and essential events for normal life. The production of glycoside residues of the proteins is only partially regulated by the genes. In this talk, I will make a brief description of what glycobiology can influence the future of neurological research arena and how glycoproteins and glycolipids affect the normal biology of the neurons. Furthermore, I will introduce you some evidences that many neurological disorders such as Alzheimer's disease and immune-mediated encephalitis have special relationships with glycobiological abnormalities. I also explain the structures and functions of lipid rafts, caveolae, and glycosynapse and their roles in the intracellular signal transduction and cell motility.

[Autopsy case of perivasculitic meningoencephalitis associated with relapsing polychondritis presenting with central nervous system manifestation]

A 76-year-old woman presented with decreased spontaneous speech and voluntary behavior. She developed impaired consciousness, as well as swelling of her ears, with subsequent gradual worsening of such symptoms. Prolonged fever, nuchal rigidity, hearing loss, and elevated plasma CRP and erythrocyte sedimentation rate were observed. CSF showed elevation of protein and IgG, and pleocytosis. Cranial MRI showed progressive brain atrophy and multiple high intensity lesions in the white matter on T2-weighted imaging and FLAIR imaging. The histopathology of biopsy sample from auricular cartilage was consistent with the relapsing polychondritis (RP). Accordingly, the diagnosis of meningoencephalitis associated with RP was made. Impaired consciousness was transiently improved by steroid pulse therapy, but subsequently worsened in spite of intensive immunosuppressive therapy with prednisolone, methotrexate and cyclosporine. Histological examination of the autopsied brain revealed perivascular lymphocyte infiltration in the pia mater and the cerebrum white matter, and inflammatory destruction of the myelin sheath. Meningoencephalitis of this case was thought to be caused by RP-associated perivascular inflammation.

A processive lipid glycosyltransferase in the small human pathogen Mycoplasma pneumoniae: involvement in host immune response

The human pathogen Mycoplasma pneumoniae has a very small genome but with many yet not identified gene functions, e.g. for membrane lipid biosynthesis. Extensive radioactive labelling in vivo and enzyme assays in vitro revealed a substantial capacity for membrane glycolipid biosynthesis, yielding three glycolipids, five phosphoglycolipids, in addition to six phospholipids. Most glycolipids were synthesized in a cell protein/lipid-detergent extract in vitro; galactose was incorporated into all species, whereas glucose only into a few. One (MPN483) of the three predicted glycosyltransferases (GTs; all essential) was both processive and promiscuous, synthesizing most of the identified glycolipids. These enzymes are of a GT-A fold, similar to an established structure, and belong to CAZy GT-family 2. The cloned MPN483 could use both diacylglycerol (DAG) and human ceramide acceptor substrates, and in particular UDP-galactose but also UDP-glucose as donors, making mono-, di- and trihexose variants. MPN483 output and processitivity was strongly influenced by the local lipid environment of anionic lipids. The structure of a major beta1,6GlcbetaGalDAG species was determined by NMR spectroscopy. This, as well as other purified M. pneumoniae glycolipid species, is important antigens in early infections, as revealed from ELISA screens with patient IgM sera, highlighting new aspects of glycolipid function.