Oligoclonal IgGs against DNA, Histones, and Myelin Basic Protein in the Cerebrospinal Fluid of Patients with Multiple Sclerosis

Multiple Sclerosis (MS) is known as a chronic demyelinating pathology of the central nervous system. The most accepted MS pathogenesis theory assigns the main role to demyelination of myelin-proteolipid shells due to inflammationrelated with autoimmune reactions. One of the features of MS patients is the enhanced synthesis of oligoclonal IgGs in the bone marrow Cerebrospinal Fluid (CSF). By antigen-specific immunoblotting after isoelectrofocusing of IgGs, oligoclonal IgGs in CSF of MS patients were revealed only against the components of Epstein-Barr virus and Chlamydia. However, there was still unknown to which human auto-antigens in MS patients oligoclonal IgGs may be produced. Here it was first shown that in the CSF of a narrow percentage of MS patients, oligoclonal IgGs are produced against their own antigens: DNA (24% patients), histones (20%), and myelin basic protein (12%). At the same time, the CSF of MS patients contains a very large amount of auto-IgGs-abzymes that hydrolyze DNA, histones, and myelin basic protein, which during isofocusing, are distributed throughout the gel from pH 3 to 10. It is concluded that these multiple IgGs-abzymes, which are dangerous to humans since stimulate development of MS, in the main are non-oligoclonal antibodies.

A method to remove the influence of fixative concentration on post-mortem T2 maps using a Kinetic Tensor model

Formalin fixation has been shown to substantially reduce T2 estimates when performing post-mortem imaging, primarily driven by the presence of bulk fixative in tissue. Prior to scanning, post-mortem tissue samples are often placed into a fluid that has more favourable imaging properties, such as matched magnetic susceptibility. This study investigates whether there is any evidence for a change in T2 in regions close to the tissue surface in post-mortem T2 maps due to fixative outflux into this surrounding fluid. Furthermore, we investigate whether a simulated spatial map of fixative concentration can be used as a confound regressor to reduce T2 inhomogeneity. To achieve this, T2 maps and diffusion tensor estimates were obtained in 14 whole, formalin fixed post-mortem brains placed in fluorinert approximately 48 hours prior to scanning. This consisted of 7 brains fixed with 10% formalin and 7 brains fixed with 10% neutral buffered formalin (NBF). Fixative outflux was modelled using a Kinetic Tensor (KT) model, which incorporates voxelwise diffusion tensor estimates to account for diffusion anisotropy and tissue-specific diffusion coefficients. Brains fixed with 10% NBF revealed a spatial T2 pattern consistent with the modelled fixative outflux. Confound regression of fixative concentration reduced T2 inhomogeneity across both white and grey matter, with the greatest reduction attributed to the KT model vs simpler models of fixative outflux. No such effect was observed in brains fixed with 10% formalin. Correlations with ferritin and myelin proteolipid protein (PLP) histology lead to an increased similarity for the relationship between T2 and PLP for the two fixative types after KT correction. Only small correlations were identified between T2 and ferritin before and after KT correction.

Anti-Myelin Proteolipid Protein Peptide Monoclonal Antibodies Recognize Cell Surface Proteins on Developing Neurons and Inhibit Their Differentiation

Using a panel of monoclonal antibodies (mAbs) to myelin proteolipid protein (PLP) peptides, we found that in addition to CNS myelin, mAbs to external face but not cytoplasmic face epitopes immunostained neurons in immature human CNS tissues and in adult hippocampal dentate gyrus and olfactory bulbs, that is neural stem cell niches (NSCN). To explore the pathobiological significance of these observations, we assessed the mAb effects on neurodifferentiation in vitro. The mAbs to PLP 50–69 (IgG1κ and IgG2aκ), and 178–191 and 200–219 (both IgG1κ) immunostained live cell surfaces and inhibited neurite outgrowth of E18 rat hippocampal precursor cells and of PC12 cells, which do not express PLP. Proteins immunoprecipitated from PC12 cell extracts and captured by mAb-coated magnetic beads were identified by GeLC-MS/MS. Each neurite outgrowth-inhibiting mAb captured a distinct set of neurodifferentiation molecules including sequence-similar M6 proteins and other unrelated membrane and extracellular matrix proteins, for example integrins, Eph receptors, NCAM-1, and protocadherins. These molecules are expressed in adult human NSCN and are implicated in the pathogenesis of many chronic CNS disease processes. Thus, diverse anti-PLP epitope autoantibodies may inhibit neuronal precursor cell differentiation via multispecific recognition of cell surface molecules thereby potentially impeding endogenous neuroregeneration in NSCN and in vivo differentiation of exogenous neural stem cells.

Wobbly syndrome in an Africa pygmy hedgehog (Atelerix albiventris): neuropathological and immunohistochemical studies

ABSTRACT: A three-year-old female African pygmy hedgehog (Atelerix albiventris), born and domiciled in Brazil, presented apathy, prostration, and difficulty to stay standing. Its parents were siblings but did not present clinical signs related to this condition. As its clinical condition worsened, the animal was euthanized and referred for necropsy. No gross lesions were found in the central nervous system (CNS). Histologically, there was vacuolation with axonal degeneration in the white matter of the CNS and in peripheral nervous tissue. The Kluver-Barrera (KB) stain confirmed demyelination in vacuolated areas. Immunohistochemistry using several neural markers confirmed astrocytosis and microgliosis associated with vacuolated areas. In addition, there was a mild decrease in the immuno intensity of myelin proteolipid protein (PLP) in these areas. These results suggest a genetic origin of the present demyelination, which resulted in the wobbly syndrome described in this report.

Effects of Intron 1 Sequences on Human PLP1 Expression: Implications for PLP1-Related Disorders

Alterations in the myelin proteolipid protein gene ( PLP1) may result in rare X-linked disorders in humans such as Pelizaeus–Merzbacher disease and spastic paraplegia type 2. PLP1 expression must be tightly regulated since null mutations, as well as elevated PLP1 copy number, both lead to disease. Previous studies with Plp1-lacZ transgenic mice have demonstrated that mouse Plp1 ( mPlp1) intron 1 DNA (which accounts for slightly more than half of the gene) is required for the mPlp1 promoter to drive significant levels of reporter gene expression in brain. However not much is known about the mechanisms that control expression of the human PLP1 gene ( hPLP1). Therefore this review will focus on sequences in hPLP1 intron 1 DNA deemed important for hPLP1 gene activity as well as a couple of “human-specific” supplementary exons within the first intron which are utilized to generate novel splice variants, and the potential role that these sequences may play in PLP1-linked disorders.

Proteolipid protein–deficient myelin promotes axonal mitochondrial dysfunction via altered metabolic coupling

Hereditary spastic paraplegia (HSP) is a neurological syndrome characterized by degeneration of central nervous system (CNS) axons. Mutated HSP proteins include myelin proteolipid protein (PLP) and axon-enriched proteins involved in mitochondrial function, smooth endoplasmic reticulum (SER) structure, and microtubule (MT) stability/function. We characterized axonal mitochondria, SER, and MTs in rodent optic nerves where PLP is replaced by the peripheral nerve myelin protein, P0 (P0-CNS mice). Mitochondrial pathology and degeneration were prominent in juxtaparanodal axoplasm at 1 mo of age. In wild-type (WT) optic nerve axons, 25% of mitochondria–SER associations occurred on extensions of the mitochondrial outer membrane. Mitochondria–SER associations were reduced by 86% in 1-mo-old P0-CNS juxtaparanodal axoplasm. 1-mo-old P0-CNS optic nerves were more sensitive to oxygen-glucose deprivation and contained less adenosine triphosphate (ATP) than WT nerves. MT pathology and paranodal axonal ovoids were prominent at 6 mo. These data support juxtaparanodal mitochondrial degeneration, reduced mitochondria–SER associations, and reduced ATP production as causes of axonal ovoid formation and axonal degeneration.