Quantitative chemical analysis of demyelination in cultured mouse spinal cord

Passive transfer of experimental autoimmune encephalomyelitis in Wistar rats: dissociation of clinical symptoms and biochemical alterations

We have used passive transfer of myelin-reactive lymphocytes in the Wistar rat model of experimental autoimmune encephalomyelitis (EAE) to investigate the nature of the central nervous system immunopathological alterations induced by these cells. Mononuclear cells from lymph nodes or spleen from sick myelin/complete Freund's adjuvant-immunized donors did not transfer clinical disease. However, depending on the previous treatment of the transferred cells, recipients develop central nervous system biochemical and histological alterations. Fresh cells from lymph nodes immediately transferred after procurement from the sick EAE donor rat were capable of inducing the most significant diminution in the content of myelin basic protein, sulfatides, and 2',3'-cyclic nucleotide-3'-phosphohydrolase activity, with concomitant inflammatory infiltrations of white matter, principally in spinal cord and cerebellar lobules. Similar alterations were observed when animals were injected with spleen mononuclear cells activated in the presence of a nonspecific mitogen as concanavalin A. However, antigen-specific activated spleen cells generated by culturing in the presence of bovine myelin induced alterations to a lesser degree. Results point to a dissociation of the clinical disease from the central nervous system biochemical and histopathological lesions occurring in the EAE-transferred Wistar rats and indicate that these alterations in EAE are induced principally by T cells activated in vivo rather than by cells activated in vitro by myelin antigens. Therefore, these findings suggest a possible participation of lymphocytes unlike the encephalitogenic T cells in the induction of the described alterations and provide a useful model to explore further the subclinical responses to this experimental disease.

Experimental autoimmune encephalomyelitis: antigen-induced inhibition of biochemical and immunohistological alterations

A comprehensive biochemical, immunological, and histological study was undertaken during suppression of experimental autoimmune encephalomyelitis (EAE) induced by antigen-specific inhibition of the immune response. Pretreatment of Wistar rats by intraperitoneal administration of low doses of saline-soluble bovine myelin or myelin basic protein (MBP) but not with ovalbumin suppresses the appearance of the clinical symptoms of EAE induced by sensitization with bovine myelin in complete Freund's adjuvant. Analysis of the central nervous system (CNS) of animals pretreated with MBP or whole myelin shows inhibition of the diminution of MBP and 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) activity observed in the EAE animals or in rats pretreated with ovalbumin. With respect to the CNS lipid content, these suppressive treatments abolish the increase in esterified cholesterol and partially revert the diminution in the content of cerebrosides and total cholesterol characteristic of the acute stage of the disease. Concomitantly, meningeal and parenchymal infiltration with mononuclear cells and deposits of immunoglobulins in the infiltrated regions as well as in spinal cord motor neurons were reduced. Analysis of the humoral response to myelin antigens shows that all EAE as well as treated animals developed antibodies to MBP and other myelin proteins. However, a higher incidence and level of these antibodies was observed in nontreated EAE animals and MBP- and ovalbumin-treated rats, while rats treated with total bovine myelin showed a highly reduced humoral response. The present results indicate that intraperitoneal treatment with soluble forms of myelin antigens, concomitant with the suppression of the clinical symptoms of the disease, markedly reduces the biochemical and histological alterations occurring in EAE animals and produces changes in the autoimmune humoral response.

Insulin-like growth factor I increases myelination and inhibits demyelination in cultured organotypic nerve tissue

The implication of insulin-like growth factor I (IGF-I) in the myelination and the repair of myelin that occur after a demyelinating process was evaluated in organotypic cultures of embryonic nerve tissue. The amount of myelin of mouse spinal cord explants exposed to media supplemented with IGF-I beginning on the first day of explantation was recorded by light-microscopic examination and quantitation of the 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) activity. After 9 days in vitro (DIV), the cultures treated with medium supplemented with 0.1-1 microgram/ml IGF-I showed a greater amount of myelin and an increase over the controls in CNPase activity between 50 and 80% at 16 DIV and 100% at 21 DIV. Total demyelination with a concomitant reduction of about 80% in the CNPase activity resulted when anti-white matter antiserum and complement were added to the nutrient medium of fully myelinated cultures. This effect was partially reverted when IGF-I was included in the demyelinating medium. The higher inhibition, about 50%, was obtained with concentrations of IGF-I between 0.1 and 0.5 micrograms/ml. To study the effect of IGF-I on remyelination, well-myelinated cultures were completely demyelinated, maintained in that state for 2 or 15 DIV and after that allowed to remyelinate for 14 days. Cultures exposed to medium supplemented with 0.01-0.1 microgram/ml IGF-I showed a degree of remyelination similar to that of the normal nutrient medium-fed cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

An in vitro micromethod for the quantitative assessment of central demyelination

We report the development of a simple and reliable method for the study of demyelination in vitro based on the measurement of 2':3'-cyclic nucleotide 3'-phosphodiesterase in isolated myelin. Using only small quantities of myelin (equivalent to 100 micrograms of myelin protein) the system was tested under conditions that are believed to approximate those found at the site of an inflammatory demyelinating lesion. Treatment with a combination of trypsin, phospholipase A2, and lysophosphatidylcholine was used to evaluate the method. This microsystem has the potential not only for testing the myelinotoxicity of soluble factors but also for investigating the involvement of inflammatory cells in the demyelinating process. Myelin degradation by elicited peritoneal macrophages could be demonstrated at relatively high densities of these cells. Nylon wool purified lymph node T cells from myelin basic protein-primed SJL/J mice, after selective expansion with antigen and interleukin 2, failed to induce any significant myelin breakdown unless a limited number of syngeneic activated macrophages were also present. T cells from mice that had been inoculated with keyhole limpet haemocyanin failed to show any effect. The advantages of this technique over other in vitro systems are that it enables the study of demyelination using syngeneic sources of myelin and defined cell populations.

Effect of antiglycolipid antisera on the lipid composition of cultured mouse spinal cords

To examine the effect of antiglycolipid antibodies on demyelination, myelinated cultures of embryonic mouse spinal cords were treated by antigalactocerebroside (anti-GC), anti-GM1; and anti-GM4 antisera, and the lipid composition of the cultures were studied. The anti-GC antiserum-treated cultures, which exhibited severe morphologic signs of demyelination, revealed a significant reduction of cerebroside. The anti-GM4 or anti-GM1 antiserum-treated cultures, which exhibited mild degrees of demyelination, also had low contents of cerebroside. These results support our previous data showing that antiglycolipid antibodies cause demyelination in cultured mouse spinal cords, and suggest a possible role of myelin-specific glycolipids in the demyelination process.

Quantitation of myelination and demyelination by the measurement of myelin basic protein by ELISA

Utilizing a competitive inhibition enzyme-linked immunosorbent assay (ELISA) we measured the amount of myelin basic protein (MBP) in brain, liver, and kidney of newborn mouse and compared these values with myelinated cerebellar explant cultures under various conditions. Explant cultures demyelinated with anti-myelin serum showed a 90% decrease in MBP when compared with controls. These results correlated with myelination and demyelination as observed by light microscopy. Newborn tissues including brain showed only negligible activity for MBP. This technique provides a sensitive and objective method for quantitating in-vitro demyelination.

Effect of insulin, proinsulin and pancreatic extract on myelination and remyelination in organotypic nerve tissue in culture

The effect of insulin, proinsulin and crude pancreatic extract was studied in organotypic nerve tissue cultures, principally in relation to the development of myelin. Cultures were exposed to media supplemented with these substances beginning on the first day of explantation. By 4 days in vitro, there was a good neuritic outgrowth from all the fragments. That from the insulin and pancreatic extract-fed were more profuse and extended further than from the control group. By 8-12 days in vitro it was also possible to observe more myelinated axons in these treated groups. The pattern of changes in the myelin associated enzyme activity, 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) paralleled the differential increase in myelination. Insulin-fed cultures showed a more rapid increase in CNPase activity, which, after 21 days in vitro reached a plateau about 30-50% over that of the controls. Cultures treated with pancreatic extract showed a similar pattern of increased activity, while in proinsulin-treated explants the activity was only significantly higher after 21 days in vitro. To study the effect of these substances on remyelination, well myelinated cultures were completely demyelinated by exposure to anti-white matter antiserum and were subsequently exposed to the same normal control or supplemented media. The amount of myelin and concomitantly the CNPase activity increased rapidly and in the same proportion between the various groups as was observed previously during primary myelination. Insulin as well as crude pancreatic extract and, to some extent, proinsulin demonstrated a marked effect on the time of onset and principally on the total amount of myelin developed by treated cultures as compared to those maintained in normal nutrient medium.

Antisera to different glycolipids induce myelin alterations in mouse spinal cord tissue cultures

To study the demyelinative effects of antibodies to glycolipids, well-myelinated cultures of mouse spinal cord tissue were exposed to antisera against galactocerebroside and two gangliosides (GM1 and GM4), as well as to anti-white matter antiserum. The demyelinative process was evaluated by morphologic and biochemical techniques. Cultures exposed to anti-white matter and anti-galactocerebroside antisera showed the most marked changes. These consisted of a decrease in the number of oligodendroglial cells and dissolution and phagocytosis of myelin. Concomitantly, the activity of 2',3'-cyclic nucleotide-3'-phosphohydrolase (CNPase) was decreased by 60-70%. This occurred within 24 h of exposure to a relatively low concentration of serum (10%). Cultures exposed to anti-GM1 and anti-GM4 antisera showed similar changes but to a lesser degree. The CNPase activity was decreased about 30% within 48 h of exposure to a 25% concentration of these antisera. This diminution represents about a 20% loss of myelin, an observation corroborated by electron microscopy where myelin but not oligodendroglial cell loss was observed. Therefore, in addition to anti-galactocerebroside activity, which was previously found to be the major antibody responsible for the demyelinating activity induced by anti-whole CNS tissue antiserum, these data suggest that antibodies to gangliosides like GM1 and GM4 might also play a role in immune-mediated demyelination, including perhaps, the human demyelinating diseases.

Correlation between 2',3'-cyclic nucleotide 3'-phosphohydrolase activity and demyelination in vitro using a syngeneic system

Cultures of myelinated SJL/J fetal mouse spinal cord were incubated with serum and lymphoid cells from syngeneic animals with experimental allergic encephalomyelitis (EAE) induced by syngeneic spinal cord homogenate (SSCH) in complete Freund's adjuvant or others injected with complete Freund's adjuvant alone. After 24 or 48 h of exposure, demyelination was determined by light microscopic examination and quantification of 2',3'-cyclic nucleotide 3'-phosphohydrolase activity. Cultures exposed to spleen or lymph node cells from SSCH-sensitized animals showed the greatest alterations in myelin and decreases in 2',3'-cyclic nucleotide 3'-phosphohydrolase activity whereas serum from these animals had less effect. Cells and serum from complete Freund's adjuvant-injected control animals also induced structural changes in myelin that were significantly less than changes induced by cells and serum from animals with EAE. These experiments show that lymphoid cells and serum obtained from SJL/J mice with acute EAE affected myelin biochemistry and morphology in syngeneic CNS cultures.