| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Regular Articles |
From the Department of Neurology,*
Kyoto University,
Kyoto, Japan, and the Kinsmen Laboratory of Neurological
Research
and the Department of Obstetrics and
Gynecology,
University of British Columbia,
Vancouver, British Columbia, Canada
| Abstract |
|---|
|
|
|---|
| Introduction |
|---|
|
|
|---|
As we reported previously, we raised a unique antibody (anti-EP) that recognizes the synthetic peptide QDENPVV, corresponding to human (h) myelin basic protein (MBP) residues 82 to 88. The anti-EP antibody can specifically detect demyelinating lesions in brains with multiple sclerosis, as well as infarcted brains.10 The anti-EP antibody is, therefore, a very useful tool for detecting demyelination. Furthermore, we have raised a new mouse monoclonal antibody (QD-9) that also recognizes QDENPVV and degenerating myelin in multiple sclerosis.11 Neither anti-EP nor QD-9 stains myelin in normal brain.10,11
To investigate oligodendroglial changes in MSA, we examined MSA brains by using anti-EP and QD-9 antibodies as markers of degenerating myelin.
| Materials and Methods |
|---|
|
|
|---|
The production of anti-EP antiserum and its characterization were reported previously.10 The monoclonal antibody QD-9 was made against a synthetic peptide corresponding to residues 69 to 88 of hMBP by the known method of Kohler and Milstein.12,13 In brief, BALB/c mice were immunized by a conjugate of the synthetic peptide with hemocyanin from keyhole limpet. Spleens were obtained from the immunized mice. Spleen cells were suspended in RPMI 1640 culture medium. The spleen cells and SP-2 myeloma cells were hybridized in 50% polyethylene glycol 1500 (Sigma Chemical Co., St. Louis, MO). The hybridomas were screened by enzyme-linked immunosorbent assay using the QDENPVV peptide. Ascites fluid was produced in mice primed with pristane by injecting 5 x 105 hybrid cells.
Immunohistochemical Procedures
Nine brains from MSA patients were examined and compared with six
brains from cases without neurological disease. Details concerning age,
sex, source of the brains, and postmortem interval are given in Table 1
. For all of the brains, fresh tissue
was fixed in 4% paraformaldehyde, pH 7.4, for 2 to 3 days before being
transferred to a maintenance solution of 20% sucrose in 0.1 mol/L
phosphate-buffered saline (PBS). Sections were cut on a freezing
microtome at a 30-µm thickness. Some sections were directly
stained by the Klüver-Barrera or Bielschowsky method to confirm
the diagnosis of MSA or of neurological normality. The MSA cases were
diagnosed by clinical records and postmortem pathological features such
as GCIs and neuronal loss. Other sections, used for immunohistochemical
staining, were rinsed for several hours in 0.01 mol/L PBS (pH 7.4)
containing 0.3% Triton X-100 (PBS-T). They were pretreated with 0.5%
H2O2 for 1 hour to reduce endogenous
peroxidase, washed in PBS-T, and blocked at room temperature for 2
hours with PBS-T containing 5% skim milk. They were then incubated for
48 to 72 hours at 4°C with one of the primary antibodies. The anti-EP
(rabbit polyclonal antibody, 1:10,000) and QD-9 (mouse monoclonal
antibody, 1:30,000) were used to visualize degenerating myelin, and
anti-ubiquitin antibody (rabbit polyclonal antibody, 1:1,000; Sigma)
was used to detect GCIs. Anti-leukocyte common antigen (mouse
monoclonal antibody, 1:1000; DAKO, Glostrup, Denmark), anti-glial
fibrillary acidic peptide (rabbit polyclonal antibody, 1:20,000; DAKO),
anti-neurofilaments (SMI-31, mouse monoclonal antibody, 1:2,000;
Sternberger Monoclonals Inc., Lutherville, MD), and anti-MAP2 (mouse
monoclonal antibody, 1:2,000; Sigma) were used as specific markers for
microglia, astrocytes, neuronal axons, and neuronal dendrites,
respectively. After incubation with primary antibody, the sections were
washed and reacted at room temperature with a biotinylated antibody
against the immunoglobulin G of the appropriate species (1:1,000,
Vector Laboratories, Burlingame, CA) for 2 hours and then for 1 hour
with the avidin-biotin-peroxidase complex (diluted 1:2000, Vector
Laboratories). They were rinsed and incubated in a staining mixture
containing 0.001% 3.3'-diaminobenzidine (Sigma), 0.6% nickel ammonium
sulfate (Fisher Scientific, Pittsburgh, PA), 0.05% imidazole, and
0.0003% H2O2 in 0.05 mol/L Tris-HCl buffer, pH
7.6, until a purple reaction product appeared. Where a brown reaction
product was desired, the same mixture without nickel ammonium sulfate
was used. The reaction was terminated by transfer of the sections to
PBS-T. Sections were mounted on glass slides, dehydrated with graded
alcohol, and coverslipped with Entellan (Merck, Darmstadt, Germany).
Some sections were double immunostained before slide mounting. After
the first staining procedure, they were pretreated with 1.0%
H2O2 for 1 hour to destroy excess peroxidase
from the first cycle and then processed with the second primary
antibody and appropriate secondary antibody as described above. The
final diaminobenzidine staining step was chosen to produce a color
different from that of the first step, by addition or elimination of
nickel ammonium sulfate. Control sections were stained without primary
antibody or with a mouse monoclonal antibody indifferent to brain
tissue. All such control sections showed no staining.
|
To compare quantitatively the intensities of Klüver-Barrera
staining and density of EP/QD-9-positive elements, we used image
analysis as follows. Severity of demyelination can be identified in
Klüver-Barrera-stained tissue sections. To determine standard
values, we measured the intensity of Klüver-Barrera staining in
80 frames from the middle cerebellar peduncle of four control cases
(cases C1, C4, C5, and C6), in which Klüver-Barrera staining was
microscopically normal. We used the sections of middle cerebellar
peduncle from six MSA cases (cases M1, M2, M4, M5, M6, and M7) to
compare Klüver-Barrera staining with EP/QD-9-positive staining.
The intensity of Klüver-Barrera staining was measured, as was the
cross-sectional tissue area taken by cell processes and cell bodies of
EP or QD-9-labeled oligodendroglia in adjacent sections. Monochromatic
photo images were taken using an Olympus BH-2 microscope with a x10
objective and a x3.3 eyepiece connected to a photo camera (Olympus,
C-35AD). After development of the negative films, these images were
examined with a Nikon 35-mm film scanner (LS-1000) set at 1350
dpi and 256 gray scale. The image files obtained were converted into
PICT files and analyzed using the NIH image analyzer program on an
Apple personal computer Power PC7500. Each image measured 1060.6
x 757.6 µm and consisted of 1893 x 1197 pixels. Five or six
images from each Klüver-Barrera-stained section and adjacent
EP/QD-9 sections were analyzed in a rectangular frame (512 x 512
pixels; 82,737 µm2). In the Klüver-Barrera-stained
sections, the average score in each rectangular frame was taken as a
measure of the severity of demyelination. The Klüver-Barrera
scores were first determined on sections of the middle cerebellar
peduncle of four control cases. The mean ± standard deviation
(SD) of these controls was used to classify the degree of demyelination
in each MSA case into five groups, ranging from 1 (very severe, less
than -6 SD from control) to 5 (not demyelinated,
mean). In
the EP/QD-9 sections, the cross-sectional area of each positive
structure was measured according to the definition of individual cell
profiles based on manual thresholding. Whether there were significant
differences in the EP/QD-9 data depending on the degree of
demyelination was assessed by the Kruskal-Wallis test for the five
groups and by the Mann-Whitney U test between all 10 pairs
(ie, group 1 versus 2, group 1 versus 3, etc.).
P values <0.05 were considered statistically significant.
Western Blotting
For Western blotting, frozen tissues from the white matter of MSA cases were homogenized in five volumes of ice-cold 10 mmol/L Tris-HCl (pH 7.4) plus 150 mmol/L NaCl (Tris-buffered saline (TBS)), containing 1 mmol/L EDTA, 1 mmol/L ethylene glycol tetraacetic acid, phenylmethylsulfonyl fluoride (100 µg/ml), leu-peptin (1 µg/ml), and pepstatin (1 µg/ml). The homogenates were centrifuged at 13,000 rpm for 20 minutes at 4°C. The pellets were suspended in TBS containing 1% sodium dodecyl sulfate. Aliquots containing approximately 100 µg of protein were electrophoresed on 15% sodium dodecyl sulfate-polyacrylamide gels and then transferred to polyvinylidene difluoride membranes (Immobilon-P, Millipore, Bedford, MA). The membranes were blocked by incubating with TBS containing 0.5% Tween-20 and 5% skim milk for 30 minutes at room temperature before being incubated overnight at room temperature with anti-EP (1:10,000) or QD-9 (1:50,000). The rabbit polyclonal and mouse monoclonal antibodies were reacted with alkaline phosphatase-labeled antibody against the immunoglobulin G of the appropriate species (1:1,000, Vector Laboratories) for 2 hours at room temperature. Alkaline phosphatase labeling was visualized by incubating with nitroblue tetrazolium (0.33 mg/ml; Life Technologies, Inc., Gaithersburg, MD) and 5-bromo-4-chloro-3-indolyl phosphate (0.165 mg/ml, Life Technologies) in 100 mmol/L Tris-HCl (pH. 9.5) containing 100 mmol/L NaCl and 50 mmol/L MgCl2.
| Results |
|---|
|
|
|---|
The anti-EP antibody and QD-9 detected the same bands on Western
blots of human cerebellar white matter. These were at 18.5 and 17.2 kd,
which corresponded to normal hMBP isoforms (Figure 1A)
.14,15
In
immunohistochemistry, each antibody stained identical structures in the
putamen of MSA brains. These were abnormal-appearing oligodendrocytic
elements (Figure 1B
(anti-EP) and 1C (QD-9)). In control brains, no
structures were stained by either anti-EP or QD-9 (Figure 1D)
.
|
|
|
In the olivopontine cerebellar system of MSA brains,
anti-EP/QD-9-positive structures were observed in the cerebellar
cortex, middle cerebellar peduncle, pons, and lower olivary complex. In
the cortices of the cerebellar hemisphere, positive fibers were located
in the granular layer (Figure 4A)
. They
seemed to be degenerating myelin sheaths of axons of Purkinje cells.
The middle cerebellar peduncle contained various densities of positive
fibers (Figure 4B)
. The cerebellar nuclei had anti-EP/QD-9-positive
fibers around the neurons (Figure 4C)
. In the ventral portion of the
pons, portions of both transverse and longitudinal fiber bundles were
stained by anti-EP/QD-9 (Figure 4D)
. In the olive complex, there were
some anti-EP/QD-9 positive fibers.
|
The neocortices have been considered to be relatively spared in MSA.
However, the anti-EP/QD-9 antibodies could detect abnormal-appearing
oligodendroglial elements in the temporal, prefrontal, and occipital
cortices, which had a normal appearance with the Klüver-Barrera
method (Figure 5A and B)
.
|
The density of anti-EP/QD-9 positive structures seemed to depend
on the severity of demyelination. Many anti-EP/QD-9-positive fibers
were observed in areas where myelin was moderately affected (Figure 6, C and D)
. In some MSA cases, the
anti-EP/QD-9 antibodies stained some fibers even in areas that appeared
normal by the Klüver-Barrera method (Figure 6, E and F)
. On the
other hand, positive structures were sparsely located in very severely
demyelinated sites (Figure 6, A and B)
.
|
KBI <
114.38; grade 3 (moderately demyelinated), 114.38
KBI
< 131.48; grade 4 (slightly demyelinated), 131.48
KBI <
148.58; and grade 5 (not demyelinated), 148.58
KBI. Comparison
between KBI and EP/QD-9 density was performed in the sections from the
middle cerebellar peduncle of the six MSA cases (Table 2)
|
|
Double staining with QD-9 and anti-ubiquitin showed that GCIs did
not contain the QD-9 epitope (Figure 8A)
.
In regions that were relatively less affected, more anti-EP-positive
fibers than GCIs could be seen (Figure 8B)
. In moderately affected
areas, both anti-EP-positive structures and GCIs were observed (Figure 8A)
. In some severely affected areas, GCIs could be observed, whereas
anti-EP-positive fibers were sparse (Figure 8C)
. Neither GCIs nor
anti-EP/QD-9-positive structures were detected in some extremely
damaged regions.
|
| Discussion |
|---|
|
|
|---|
The double staining of specific markers and EP/QD-9 showed clearly that EP/QD-9-positive structures are not from astroglia, microglia, or neurons. Taking these results together with the specificity of these two antibodies against the partial sequence of MBP, We concluded that EP/QD-9-positive structures are oligodendroglial elements. The anti-EP/QD-9 antibodies stained the fibrils and cell bodies of damaged oligodendrocytes in the white matter of MSA brains, whereas no positive structures were observed in the control brains. Anti-MBP antibodies and the Klüver-Barrera method have been used to detect demyelinating lesions. They are, however, not always sensitive enough to visualize minor MBP changes that may occur in white matter. In fact, the anti-EP/QD-9 antibodies detected abnormal-appearing oligodendrocytic elements in areas where no apparent changes were observed by conventional methods. The anti-EP and QD-9 antibodies are, therefore, very sensitive tools for investigating myelin pathology in MSA as well as in multiple sclerosis.10
MSA is pathologically characterized by cell loss and gliosis occurring in selective regions such as the substantia nigra, caudate, putamen, globus pallidus, inferior olives, pons, and cerebellum.16,17 Structures positive for anti-EP and QD-9 antibodies were seen in these regions. In the middle cerebellar peduncle, where demyelination is always observed, anti-EP and QD-9 both detected intensely positive fibers and cell bodies intensely. All examined sections of the pons, caudate, putamen, and globus pallidus (especially the pars externa) from MSA brains contained richly positive structures. Because demyelination in these areas is thought to be secondary to neuronal loss, the anti-EP/QD-9-positive structures in these areas may result from secondary demyelination.
The intensity and density of anti-EP/QD-9-positive structures depended on the severity of demyelination. The image analysis gave quantitative support for this impression. Moderately or slightly affected regions had the most prominent staining with these antibodies. Severely affected regions showed little or no anti-EP/QD-9 staining. The epitope recognized by anti-EP/QD-9 may have been destroyed in these very severely affected regions. The same phenomena were observed in central regions of multiple-sclerotic plaques.10 Anti-EP/QD-9 positive structures were observed in neocortical white matter that was examined, such as that of the temporal or frontal lobes, whereas the conventional Klüver-Barrera method failed to detect the myelin degeneration. Involvement of cerebral cortex in MSA has been studied by several groups. Motor cortex has been reported to be the most GCI-rich cerebral cortical area.2,7,18,19 Ubiquinated neuronal inclusions have been found in the subiculum and CA1 of Ammon's horn.20 A recent report indicated some neuronal damage in prefrontal cortex, dentate gyrus, and parahippocampal gyrus in MSA brains.21 These data showed that neuronal damage in the cerebral cortex in patients with MSA is more extensive than previously thought. Neuronal loss itself in the cerebral neocortices is, however, not as marked as the massively degenerated oligodendrocytes stained by anti-EP/QD-9. Because damage in these areas to projection fibers from brain stem, basal ganglia, or sick neurons of neocortices cannot be excluded, more studies are needed to prove that oligodendroglial involvement is one of the primary events in MSA. The present results, however, show that damage of oligodendroglia can be detected in the early stages of the degenerative process in MSA.
GCIs are one of the hallmarks of pathology in MSA brains.2,4,7,22 Immunohistochemical studies have shown that MBP is not a component of GCIs.23-25 The present study also showed that GCIs do not contain the anti-EP/QD-9 epitope, corresponding to hMBP 82 to 86. The appearance of GCIs is thought to precede the other changes of neuronal loss, gliosis, and myelin pallor.7 In this study, anti-EP/QD-9-positive structures in MSA brains were observed widely, including GCI-free regions. The presence of anti-EP/QD-9-positive struc-tures and GCIs may be early signs of oligodendroglial degeneration in MSA. Further studies are obviously needed to reveal the precise relationship between the pathogenesis of MSA and early oligodendroglial degeneration.
| Acknowledgements |
|---|
| Footnotes |
|---|
Supported by grants from the Jack Brown and Family A. D. Research Fund (Vancouver, British Columbia, Canada), donations from individual British Columbians, and a Grant-in-Aid for Scientific Research on Priority Areas and a grant for amyotrophic lateral sclerosis from the Japanese Ministry of Education, Science and Culture.
Accepted for publication May 20, 1998.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
Y. J. C. Song, D. M.S. Lundvig, Y. Huang, W. P. Gai, P. C. Blumbergs, P. Hojrup, D. Otzen, G. M. Halliday, and P. H. Jensen p25{alpha} Relocalizes in Oligodendroglia from Myelin to Cytoplasmic Inclusions in Multiple System Atrophy Am. J. Pathol., October 1, 2007; 171(4): 1291 - 1303. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Higuchi, B. Zhang, M. S. Forman, Y. Yoshiyama, J. Q. Trojanowski, and V. M.-Y. Lee Axonal Degeneration Induced by Targeted Expression of Mutant Human Tau in Oligodendrocytes of Transgenic Mice That Model Glial Tauopathies J. Neurosci., October 12, 2005; 25(41): 9434 - 9443. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. Stefanova, M. Reindl, M. Neumann, C. Haass, W. Poewe, P. J. Kahle, and G. K. Wenning Oxidative Stress in Transgenic Mice with Oligodendroglial {alpha}-Synuclein Overexpression Replicates the Characteristic Neuropathology of Multiple System Atrophy Am. J. Pathol., March 1, 2005; 166(3): 869 - 876. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Specht, M. Minnerop, M. Abele, J. Reul, U. Wullner, and T. Klockgether In Vivo Voxel-Based Morphometry in Multiple System Atrophy of the Cerebellar Type Arch Neurol, October 1, 2003; 60(10): 1431 - 1435. [Abstract] [Full Text] [PDF] |
||||
![]() |
D J Burn and E Jaros Multiple system atrophy: cellular and molecular pathology Mol. Pathol., December 1, 2001; 54(6): 419 - 426. [Abstract] [Full Text] [PDF] |
||||
![]() |
Z. Ahmed, D. Gveric, G. Pryce, D. Baker, J. P. Leonard, and M. L. Cuzner Myelin/Axonal Pathology in Interleukin-12 Induced Serial Relapses of Experimental Allergic Encephalomyelitis in the Lewis Rat Am. J. Pathol., June 1, 2001; 158(6): 2127 - 2138. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. W. Dickson, W.-K. Liu, J. Hardy, M. Farrer, N. Mehta, R. Uitti, M. Mark, T. Zimmerman, L. Golbe, J. Sage, et al. Widespread Alterations of {alpha}-Synuclein in Multiple System Atrophy Am. J. Pathol., October 1, 1999; 155(4): 1241 - 1251. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Castellani Multiple System Atrophy : Clues from Inclusions Am. J. Pathol., September 1, 1998; 153(3): 671 - 676. [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |