Suppression of remyelination in the CNS by X-irradiation

Summary Rat and cat spinal cords were exposed to 2000, 3000 or 4000 rads of x-irradiation prior to producing an area of primary demyelination in the dorsal columns by the injection of lysolecithin. In animals irradiated with 4000 rads no remyelination by either Schwann cells or oligodendrocytes occurred. With 2000 rads both types of remyelination occurred, but when compared to unirradiated controls, central remyelination was less extensive, while Schwann cells remyelinated a greater percentage of axons. With 3000 rads the results were variable, some animals responded similarly to those in the 4000 rad group, whereas others responded as the 2000 rad animals.Oligodendrocytes were found among the persistently demyelinated axons in the 4000 rad animals and their processes were associated with, but only rarely formed a myelin sheath round, the demyelinated axons. It was concluded that irradiation damage to local cells was responsible for the inhibition of remyelination but it could not be determined if this was due to its effect on the oligodendrocytes alone. The origin of the oligodendrocytes found among the demyelinated axons is discussed in this context.     

Targeting remyelination treatment for multiple sclerosis

Since disability in multiple sclerosis (MS) is a product of neurodegeneration and deficient remyelination, the ability to enhance neuroregeneration and myelin regeneration in MS is an enticing goal for MS drug development. In particular, remyelination treatments could promote return of neurological function and also prevent further axonal loss and neurodegeneration in MS due to trophic effects of myelin. The study of remyelination has advanced dramatically in the last several years such that a number of pathways inhibiting remyelination have been discovered, including those involving LINGO-1, Notch-1, hyaluronan, retinoid X receptor, and wnt/ß-catenin. Other approaches such as high throughput drug screening for remyelination drugs have caught fire, with identification of dozens of known drugs with oligodendrocyte maturation stimulatory effects. Several drugs identified through screens and other mechanisms are in the process of being further evaluated for remyelination in MS and MS models. We discuss the potential molecular targets and the variety of mechanisms towards drug identification and development in remyelination for MS.     

Lack of interferon-beta leads to accelerated remyelination in a toxic model of central nervous system demyelination

Interferon-beta (IFN-β) is a pleiotropic cytokine that is known to modulate the immune response in multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system (CNS). Spontaneous remyelination and repair mechanisms in MS are mostly insufficient and contribute to clinical disability. Here, we investigated whether IFN-β has a potential in modifying the extent of de- and remyelination in a toxic model of CNS demyelination induced by the copper chelator cuprizone. IFN-β deficient (k/o) mice showed an accelerated spontaneous remyelination. However, the amount of remyelination after 6 weeks did not differ between the two groups. Demyelination in IFN-β k/o mice was paralleled by a diminished astrocytic and microglia response as compared with wildtype controls, whereas the accelerated remyelination was paralleled by an increased number of oligodendrocyte precursor cells (OPC) within the demyelinated lesion at the beginning of the remyelination phase. We hypothesize that the absence of IFN-β leads to more efficient recruitment and proliferation of OPC already during demyelination, thus allowing early remyelination. These results demonstrate that IFN-β is able to alter remyelination in the absence of an immune-mediated demyelination. The first two authors contributed equally to this work.     

Osteopontin is extensively expressed by macrophages following CNS demyelination but has a redundant role in remyelination

Osteopontin (OPN) is a key immunoregulator in the autoimmune-mediated demyelinating disease multiple sclerosis. OPN may also play a role in the remyelination since it is 1) a ligand for αV integrins, several of which regulate the properties of the oligodendrocyte precursor cells (OPCs) primarily responsible for remyelination, and 2) enhances myelin membrane formation in OPC lines. Here we show that OPN is expressed at high levels during remyelination of toxin-induced demyelination. The increased expression is due to mRNA expression in macrophages and follows differences in macrophage responses to demyelination in young and old adult animals. To identify the role of OPN in remyelination focal demyelination was induced in wild-type and OPN^−/− mice. There was no difference in the rate of remyelination between the two groups indicating that OPN is not a critical component of remyelination.     

NCAM expression induces neurogenesis in vivo

Neural cell adhesion molecule (NCAM) plays an important role during neural development and in the adult brain, whereby most functions of NCAM have been ascribed to its unique polysialic acid (PSA) modification. Recently we presented evidence suggesting that expression of NCAM in vivo interferes with the maintenance of forebrain neuronal stem cells. We here aimed at investigating the fate of cells generated from NCAM-overexpressing stem cells in postnatal mouse brain and at elucidating the functional domains of NCAM mediating this effect. We show that ectopic expression of the NCAM140 isoform in radial glia and type C cells induces an increase in cell proliferation and consequently the presence of additional neuronal type A cells in the rostral migratory stream. A mutant NCAM protein comprising only fibronectin type III repeats and immunoglobulin-like domain 5 was sufficient to induce this effect. Furthermore, we show that the neurogenic effect is independent of PSA, as transgenic NCAM is not polysialylated in radial glia and type C cells. These results suggest that heterophilic interactions of NCAM with other components of the cell membrane must be involved.     

多发性硬化患者脑脊液sIL-2R水平变化的研究

目的：探讨可溶性白细胞介素２受体（ｓＩＬ－２Ｒ）在多发性硬化（ＭＳ）发病机理中的作用及其临床意义。方法：采用双抗体夹心ＥＬＩＳＡ法对４４例ＭＳ患者脑脊液ｓＩＬ－２Ｒ水平进行了检测。结果：ＭＳ组脑脊液ｓＩＬ－２Ｒ水平显著高于正常对照组,脑脊液ｓＩＬ－２Ｒ水平变化与ＭＳ患者疾病活动状态及病残程度密切相关。结论：ＭＳ患者体内Ｔ淋巴细胞处于活化状态,ｓＩＬ－２Ｒ在ＭＳ发病机理中发挥着重要作用,检测脑脊液ｓ     

Modifications of the cerebrospinal fluid IgG concentrations in patients with multiple sclerosis treated with intrathecal steroids

Summary Forty-one patients with multiple sclerosis (MS), in the acute exacerbation phase of the disease, were treated with three or four intrathecal injections of triamcinolone retard, 40 mg. Cerebrospinal fluid (CSF) specimens were collected at the first and at the last lumbar puncture, and analyzed for IgG and albumin. There was a decrease of CSF IgG concentration in the specimens of 85% of the cases which were collected at the last lumbar puncture, compared to the initial concentration. Similarly, the CSF IgG/albumin ratio in the last specimens collected were reduced in 78% of the cases. Both these results are statistically significant.Presented to the Meeting of Swiss Neuropathologists with International Participation, St. Moritz, 6 to 9 March 1978     

Prostaglandin levels in cerebrospinal fluid from multiple sclerosis patients in remission and relapse

Radioimmunoassay (RIA) techniques have been employed to determine prostaglandin (PG) levels in the cerebrospinal fluid (CSF) from multiple sclerosis (MS) patients in remission and relapse and in subjects with other neurological diseases (OND). PGE and PGF₂α concentrations in spinal fluid from MS patients in relapse were significantly lower than values estimated during remission and in individuals with OND of the central nervous system (CNS). These observations are discussed in relation to the clinical state of patients with demyelinating disease together with a consideration of the concept that disordered immune mechanisms contribute a central role in the pathogenesis of MS.     

Overcoming remyelination failure in multiple sclerosis and other myelin disorders

Protecting axons from degeneration represents a major unmet need in the treatment of myelin disorders and especially the currently untreatable secondary progressive stages of multiple sclerosis (MS). Several lines of evidence indicate that ensuring myelin sheaths are restored to demyelinated axons, the regenerative process of remyelination, represents one of the most effective means of achieving axonal protection. Remyelination can occur as a highly effective spontaneous regenerative process following demyelination. However, for reasons that have not been fully understood, this process is often incomplete or fails in MS. Recognizing the reasons for remyelination failure and hence identifying therapeutic targets will depend on detailed histopathological studies of myelin disorders and a detailed understanding of the molecular mechanisms regulating remyelination. Pathology studies have revealed that chronically demyelinated lesions in MS often fail to repair because of a failure of differentiation of the precursor cell responsible for remyelination rather than a failure of their recruitment. In this article we review three mechanisms by which differentiation of precursor cells into remyelinating oligodendrocytes are regulated-the Notch pathway, the Wnt pathway and the pathways activated by inhibitor of differentiation in myelin debris-and indicate how these might be pharmacologically targeted to overcome remyelination failure.     

The concentration of IgM in the cerebrospinal fluid of neurological patients

The level of IgM was determined by Particle Counting Immunoassay in the cerebrospinal fluid. In non-neurological patients (N = 20) the mean was 97.5 μg/l with the upper reference limit at 380 μg/1. The mean IgM index was 0.021 with the upper reference limit at 0.071. Of 21 patients with stroke, 5 had an IgM index exceeding the reference limit. High levels and indices of IgM were observed in most patients (N = 27) with infectious meningo-encephalitis. In this group, the IgM index was abnormal in about 30% of cases with a normal total protein content, and was more often increased than the IgG index. In multiple sclerosis patients (N = 80), the IgM index was increased in 32%. In this disease very high values of IgM index (> 0.13) were never associated with very high values of IgG index (> 1.8). A significantly higher proportion of males was found in the group of patients with very high values of IgM index (N = 11). No significant influence of the age of onset, the interval between onset and sampling and clinical state was observed. However, of 10 patients with a multiple sclerosis history exceeding 15 years none had an IgM index exceeding the upper reference limit. Four patients with multiple sclerosis had a high IgM index without either an increase of the IgG index or the presence of oligoclonal bands.     

Schwann cell and oligodendrocyte remyelination in lysolecithin-induced lesions in irradiated rat spinal cord

Localised irradiation of adult rat spinal cord was achieved by implanting for 2 weeks a 192Ir pin alongside vertebral segments in the thoraco-lumbar region of the spinal column. Following removal of the implant, lysolecithin (LPC) was injected directly into the dorsal columns in order to induce demyelination in the most intensely irradiated segments of spinal cord. Eight weeks after LPC injection, remyelination was much less extensive in dorsal columns which absorbed more than 40Gy than in LPC lesions in less intensely irradiated spinal cords or in unirradiated animals. No oligodendrocytes, few astrocyte processes and little myelin debris lay among the demyelinated axons. However, capillary vessels were surrounded by astroglial end-feet so that the glial-limiting membrane remained intact in the demyelinated regions. There were some oligodendrocyte remyelinated fibres around the edges of the demyelinated zones but none among the naked axons. Schwann cells, which probably migrated into the lesions from the proximal segments of the dorsal roots, provided some fibres with myelin sheaths. These remyelinated fibres abutted demyelinated axons without an intervening glial limiting membrane or astrocyte process. Oligodendrocytes may fail to migrate into the demyelinated regions because of the scarcity of astrocyte processes. A possible explanation for the limited Schwann cell remyelination may be that the presence of astroglial end-feet around capillaries deprived Schwann cells of ready access to the demyelinated regions.     

Limited remyelination of CNS axons by Schwann cells transplanted into the sub-arachnoid space

Areas of primary demyelination which did not subsequently remyelinate spontaneously were prepared in the cat spinal cord by injecting small volumes of ethidium bromide into tissue which had previously been exposed to 40 Grays of X-irradiation. Autologous peripheral nerve tissue was placed in the sub-arachnoid space over such lesions, either at the time of injecting ethidium bromide, or at 14 days or 28 days after injecting ethidium bromide. The extent of Schwann cell remyelination was assessed 28 days after transplantation. In no case were all the demyelinated axons remyelinated; rather, remyelination was limited to axons near to blood vessels. It was concluded that Schwann cells migrated from the transplanted tissue into the lesion via the perivascular space and that they failed to remyelinate the bulk of demyelinated axons because of an absence within the CNS of suitable extracellular matrix.     

Which syringomyelia is truly associated with multiple sclerosis?

Necrosis of the spinal cord within multiple sclerosis (MS) lesions was suggested as a putative cause of syringomyelic cavity development in MS. A number of evidences suggest however that mechanisms other than necrosis are pathogenetically relevant for cavity formation, possibly depending on the atypical topographical distribution of the demyelinative lesion and on the increased cerebrospinal fluid pressure into the central canal below the compression. Not coincidentally, the hypothesis of post-necrotic and ex-vacuo mechanisms leading to cavitation derives from Japanese studies where MS is characterised by high tissue destructive capability and, besides its rarity, has many differences from the more common Western MS type and similarities with the acute disseminated encephalomyelitis (ADEM). Our opinion is that different MS types (Asian and Western) are accompanied by nonuniform mechanisms of syrinx formation and that the Asian MS type shares common, post-necrotic mechanisms with ADEM.     

Spinal cord multiple sclerosis lesions in Japanese patients: Schwann cell remyelination occurs in areas that lack glial fibrillary acidic protein (GFAP)

Summary To extend earlier observations on Schwann cell remyelination in multiple sclerosis (MS) lesions (Itoyama et al. 1983) we immunostained spinal cord sections from eight Japanese MS patients with antiserum to P_o glycoprotein, a major constituent of peripheral nervous system (PNS) myelin, myelin basic protein (MBP), and glial fibrillary acidic protein (GFAP). Spinal cord sections from six of the eight Japanese MS patients contained large clusters of peripheral myelin sheaths with anti-P_o immunoreactivity. In lesions found in four of the six patients, thousands of P_o-stained PNS myelin sheaths were present. Necrosis was prominent in these lesions which included more than half of the spinal cord's transverse area. The number and density of regenerating myelin sheaths of peripheral origin were much greater than we observed in MS spinal cord lesions of white people (Itoyama et al. 1983). Anti-GFAP immunoreactivity was present in most brain and spinal cord lesions. However, the areas in lesions that contained large groups of PNS myelin sheaths lacked anti-GFAP immunoreactivity. Our data suggest that spinal MS lesions that are large, severely demyelinated, and partially necrotic may contain factors that inhibit fibrous astrogliosis. These factors, other substances in the large lesions and/or the lack of astrocytic scarring could then promote Schwann cell invasion, multiplication, and remyelination of surviving axons.     

Notch1 and its ligand Jagged1 are present in remyelination in a T-cell- and antibody-mediated model of inflammatory demyelination

The Notch receptor and its ligands are involved in myelination in central nervous system (CNS) development. Re-expression of this pathway in the adult CNS has been proposed to hamper remyelination in multiple sclerosis. Previous studies also revealed that pharmacological inhibition of Notch signaling ameliorates experimental autoimmune encephalomyelitis (EAE). However, in a recent study in toxin-induced demyelination constituents of the Notch signaling pathway were demonstrated in remyelinating lesions indicating that remyelination may occur in the presence of Notch signaling. We examined the expression of Notch1-immunoreactivity (IR) and Jagged1-IR in EAE induced by myelin-oligodendrocyte glycoprotein (MOG). In this model, the combined action of T cells, antibodies and the complement cascade yields a pathology closely reflecting multiple sclerosis. Notch1 and its ligand Jagged1 were differentially expressed in the lesions of MOG-EAE. Notch1-IR on macrophages was highest in actively demyelinating and lowest in remyelinating lesions. The amount of Notch1-positive astrocytes increased during the lesion evolution from demyelination to remyelination. Notch1-positive oligodendrocytes were exclusively present in remyelinating lesions and not found in lesions without signs of remyelination. Astrocytes represented the major source of Jagged1-IR in demyelination and remyelination. In conclusion, our study proves that constituents of the Notch pathway are expressed in remyelination in an animal model of T-cell- and antibody-mediated CNS demyelination. Thus, it is unlikely, at least in the paradigm of MOG-EAE, that Notch signaling is responsible for a failure of remyelination. M. K. S. receives grant support from Biogen Idec; R. W. holds a Heisenberg fellowship of Deutsche Forschungsgemeinschaft (DFG We 1947/4-2).     

Isotachophoresis evaluation of synthesis of intrathecal IgG subfractions in multiple sclerosis

Summary Cerebrospinal fluid (CSF) and serum samples from patients with multiple sclerosis and other neurological diseases were examined by capillary isotachophoresis (ITP). The percentage and the rate of synthesis of CSF IgG which migrated slowly with ITP were calculated.CSF specimens of most patients with multiple sclerosis contained increased percentages of slowly migrating IgG (slow IgG), corresponding to IgG oligoclonal bands in the high-alkaline region on isoelectric focusing. The patients with multiple sclerosis were found to have increased intrathecal synthesis of slow IgG, which correlated closely with the rate of intrathecal CNS IgG synthesis calculated by Tourtellotte's formula.

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Zusammenfassung Liquor und Serum von Patienten mit Multipler Sklerose und anderen neurologischen Erkrankungen wurden mittels Kapillar-Isotachophoresis (ITP) untersucht. Es wurde berechnet, welchen Anteil das IgG im Liquor, welcher langsam mit der ITP wanderte, ausmachte und wie seine Synthesegeschwindigkeit war. Bei den meisten Patienten mit Multipler Sklerose enthielt der Liquor einen erhöhten Anteil von langsam wandernden IgG, welches oligoclonalen Banden im hochalkalischen Bereich beim isoelectric focusing entsprach. Es wurde gefolgert, daß die Patienten mit Multipler Sklerose eine erhöhte intrathekale Synthese des langsamen IgG aufwiesen, wobei dies eng korrelierte mit dem Anteil der intrathekalen Liquor-IgG-Synthese, wie sie nach der Tourtellotteschen Formel errechnet werden kann.

     

多发性硬化患者外周血和脑脊液淋巴细胞亚群的观察

用碱性磷酸酶抗酸酶法检查了４６例多发性硬化活动期患者外周血和脑脊液的淋巴细胞亚群。结果显示：活动期ＭＳ者外周血ＣＤ＾＋４，ＣＤ＾＋９细胞较对照组减少，ＣＤ＾＋２５细胞，ＣＤ＾＋４／ＣＤ＾＋８比值较对照组升高。ＣＳＦ中ＣＤ＾４，ＣＤ＾＋２５细胞，ＣＤ＾＋４／ＣＤ＾＋８比值较对照组升高，ＣＤ＾＋８细胞降低，且ＣＳＦ中淋巴亚群均高于自身外周血中的相应细胞。     

Expression of leukemia inhibitory factor in the cerebrospinal fluid of patients with multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system, characterized by infiltration of immune cells in the central nervous system, localized myelin destruction and loss of oligodendrocytes. Early detection of MS may be possible via blood and cerebrospinal fluid (CSF) tests based on disease pathology. Leukemia inhibitory factor (LIF), a neurotrophic cytokine, has previously been shown to limit autoimmune demyelination and oligodendrocyte loss in a murine model of MS. Given its potential role in neural cell death and survival, in the present study we measured expression of LIF in serum and CSF from patients with relapsing-remitting MS (n = 46) and control subjects (n = 42). We used western blot analysis and enzyme-linked immunosorbent assays (ELISA), to study LIF expression. Western blot analysis revealed that LIF was present in all CSF samples, and densitometric analysis showed that relative expression was significantly higher in CSF from patients with MS than in controls (p < 0.001). ELISA analysis showed that the concentrations of LIF in both the serum (87.5 ± 11.46 ng/mL) and CSF (56 ± 10.72 ng/mL) of MS patients were significantly higher than those in control subjects (52 ± 8.23 ng/mL, 7.8 ± 3.76 ng/mL, respectively; p < 0.0001 for both serum and CSF), despite there being no significant difference in total protein concentration between the two groups (p = 0.52 for serum, p = 0.2 for CSF). Our data suggest that serum and CSF concentrations of LIF may provide additional useful information during the differential diagnosis of MS. Our findings also indicate that LIF could be significantly involved in the pathophysiology of MS.