Cyclophosphamide attenuates the degenerative changes induced by CSF from patients with amyotrophic lateral sclerosis in the neonatal rat spinal cord

Our earlier studies have shown that cerebrospinal fluid (CSF) of patients with amyotrophic lateral sclerosis (ALS), when intrathecally injected into the neonatal rats, produces an aberrant phosphorylation of neurofilaments (NF) in the ventral horn neurons and reactive astrogliosis in the spinal cord. We wanted to investigate the effect of cyclophosphamide in the spinal cords of neonatal rats exposed to ALS-CSF. A single dose (5 microg in 5 microl saline) of cyclophosphamide was injected, 24 h after the administration of CSF samples from ALS and non-ALS neurological patients into the spinal subarachnoid space of 3-day-old rat pups. Rats were sacrificed after a period of 24 h, and stained with antibodies against the phosphorylated NF (SMI-31 antibody) and glial fibrillary acidic protein (GFAP). Cyclophosphamide treatment resulted in a 50% decrease in the number of SMI-31 stained neuronal soma in ventral horns of spinal cords of ALS-CSF exposed rats. This was accompanied by a decrease in the number of GFAP immunoreactive astrocytes. Furthermore, lactate dehydrogenase (LDH) activity was also decreased significantly, following cyclophosphamide treatment. These results suggest that cyclophosphamide could exert a neuroprotective effect against the neurotoxic action of factor(s) present in the ALS-CSF.     

(-)-Deprenyl alleviates the degenerative changes induced in the neonatal rat spinal cord by CSF from amyotrophic lateral sclerosis patients.

Previous studies from our laboratory suggest the presence of toxic factor(s) in the cerebrospinal fluid (CSF) of patients with amyotrophic lateral sclerosis (ALS) which induces degenerative changes in the spinal cord neurons. The present work was carried out to investigate the role of (-)-deprenyl in attenuating these degenerative changes. CSF samples from ALS and non-ALS neurological patients were injected into the spinal subarachnoid space of 3-day-old rat pups, followed by a single dose (0.01 mg/kg body weight) of (-)-deprenyl, administered 24 h after CSF injection. After a further period of 24 h, the rats were sacrificed and the spinal cord sections were stained with antibodies against phosphorylated neurofilament (NF, SMI-31 antibody) and glial fibrillary acidic protein (GFAP). Activity of lactate dehydrogenase (LDH) was also measured. (-)-Deprenyl injection resulted in a significant (61%) decrease in the number of SMI-31 stained neuronal soma in the ventral horn of the spinal cord of ALS CSF exposed rats. This was accompanied by a reduction in the astrocytes immunoreactive for GFAP. There was also a significant (35%) decrease in the LDH activity following (-)-deprenyl treatment. These results suggest that (-)-deprenyl may confer neuroprotection against the toxic factor(s) present in ALS CSF.     

Neurofilament phosphorylation is enhanced in cultured chick spinal cord neurons exposed to cerebrospinal fluid from amyotrophic lateral sclerosis patients

Amyotrophic lateral sclerosis (ALS), a neurodegenerative disease, is characterized by degeneration of lower and upper motor neurons. Serum and cerebrospinal fluid (CSF) of ALS patients have been found to exert toxic effects on neurons in culture. We report here increased phosphorylation of neurofilaments (NF) in the soma of chick spinal cord neurons in culture when exposed to CSF of ALS patients. Spinal cord neurons were cultured from 10-day embryonic chick and exposed to culture medium supplemented with CSF or serum (10%) from ALS and non-ALS patients for 48 h. There was a significant increase in the number of neuronal soma staining with antibodies against phosphorylated NF, following exposure to CSF from ALS patients. Such an increase, however, was not observed in cultures exposed to serum from ALS patients and also serum and CSF from non-ALS patients. These results suggest that the CSF of ALS patients may contain factor(s) which induces aberrant phosphorylation of NF in the soma, a probable forerunner to the formation of neurofibrillary tangles and eventual degeneration of neurons.Supported by a research grant from the National Institute of Mental Health and Neuro Sciences, Bangalore, India     

Enhanced Fos expression in rat lumbar spinal cord cultured with cerebrospinal fluid from patients with amyotrophic lateral sclerosis.

The etiology of amyotrophic lateral sclerosis (ALS) remains unknown although an existence of neurotoxic substances in cerebrospinal fluid (CSF) from ALS patients have been postulated. In order to investigate a possible effect of CSF from ALS patients on cellular signaling in spinal neurons, we compared Fos-like immunoreactivity (Fos-LI) in organotypic cultures of rat lumbar spinal cord after addition of CSF from ALS patients or another neurologic disease. Fos-LI was normally present predominantly in dorsal horn neurons, whereas only a few ventral horn neurons were positive for Fos-LI. The number of Fos-LI positive neurons significantly increased in dorsal horn with addition of CSF from ALS patients as well as glutamate at 100 microM. However, the increase was not observed with addition of CSF from other neurologic diseases. The increase in Fos-LI positive neurons in dorsal horn was reversed by a further supplement of MK801, an N-methyl-D-aspartate (NMDA) receptor antagonist, but not of CNQX, an alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)/kainate antagonist. These results indicate that there may be substances in CSF from ALS patients that stimulate Fos expression in certain populations of spinal neurons via the NMDA receptors.     

Enhanced Fos expression in rat lumbar spinal cord cultured with cerebrospinal fluid from patients with amyotrophic lateral sclerosis

Abstract

School, Okayama, Japan The etiology of amyotrophic lateral sclerosis (ALS) remains unknown although an existence of neurotoxic substances in cerebrospinal fluid (CSF) from ALS patients have been postulated. In order to investigate a possible effect of CSF from ALS patients on cellular signaling in spinal neurons, we compared Fos-like immunoreactivity (Fos-LI) in organotypic cultures of rat lumbar spinal cord after addition of CSF from ALS patients or another neurologic disease. Fos-LI was normally present predominantly in dorsal horn neurons, whereas only a few ventral horn neurons were positive for Fos-LI. The number of Fos-LI positive neurons significantly increased in dorsal horn with addition of CSF from ALS patients as well as glutamate at 100 μM. However, the increase was not observed with addition of CSF from other neurologic diseases. The increase in Fos-LI positive neurons in dorsal horn was reversed by a further supplement of MK801, an N-methyl-D-aspartate (NMDA) receptor antagonist, but not of CNQX, an a-amino-3-hydroxy-5-methyl-4- isoxazole propionic acid (AMPA)/kainate antagonist. These results indicate that there may be substances in CSF from ALS patients that stimulate Fos expression in certain populations of spinal neurons via the NMDA receptors. [Neurol Res 1999; 21: 309-312]     

Expression of ciliary neurotrophic factor is maintained in spinal motor neurons of amyotrophic lateral sclerosis

Ciliary neurotrophic factor (CNTF) was originally identified as a potent survival factor for a variety of neuronal cell types in vitro and in vivo and in particular in spinal motor neurons of embryonic chick and rat. Using a monoclonal antibody against CNTF (clone 4–68) we analysed the expression of CNTF in paraffin sections of seven human brains and spinal cords immunocytochemically using the ABC method and compared these results with sections of the spinal cords of patients suffering from amyotrophic lateral sclerosis (ALS). In normal human tissue of the central nervous system CNTF immunoreactivity was found in most of the motor neurons of the motor cortex and ventral horn, neurons of the nucleus oculomotorius, intermediolateralis, thoracicus, ependymal cells as well as in smooth muscle cells and endothelial cells of small arteries. A reduced number of astrocytes showed a positive immunocytochemical reaction. In peripheral nerves and nerve roots of the spinal cord we also found a positive staining of Schwann cells and some axons. These immunoreactions could be confirmed by Western blot analyses. Next we analysed postmortem paraffin sections of the spinal cord of seven patients suffering from ALS (age range 30–76 years, median age 46 years, female/male = 4:3). We found CNTF immunoreactivity in most of the motor neurons of the ventral horn in 5 cases. In two cases the number of positively stained motor neurons was less. From these results we conclude that CNTF is expressed in a high number of upper and lower motor neurons in the human CNS and that its expression is maintained in ALS patients.     

Differential binding of antibodies against the neurofilament triplet proteins in different avian neurons

Using monospecific antisera against each of the three chicken neurofilament (NF) proteins, NF70, NF160 and NF180, the distribution of each of these proteins in several types of neurons was examined by immunohistochemistry. Striking differences were observed in the relative staining by the three antibodies when the soma of different types of neurons were compared, and also when the soma of some neurons were compared with their axons. Both the soma and axons of dorsal root sensory neurons were brightly stained by each of the antisera. The soma of spinal cord ventral horn neurons, however, were stained only by A-NF70 and A-NF180, not by A-NF160. The axons of these neurons were uniformly stained by A-NF70 and A-NF180, while only gradually becoming NF160-positive over the first several hundred microns. The lack of staining by A-NF160 was also observed in many neuronal soma in cultures of dissociated spinal cord cells. The soma and dendrites of adult cerebellar Purkinje cells were weakly stained by A-NF70 and A-NF180 and not at all by A-NF160, but both A-NF70 and A-NF180 yielded prominent staining of immature Purkinje cells and dendrites. These results suggest that the three NF proteins may be unequally distributed within the soma and processes of different types of neurons and/or may be subject to regionally selective modification.     

Amyotrophic lateral sclerosis: glutamate dehydrogenase and transmitter amino acids in the spinal cord.

Measurements were taken of the activity of glutamate dehydrogenase (GDH) and the levels of transmitter amino acids in anatomically dissected regions of cervical and lumbar spinal cord in eight patients dying with amyotrophic lateral sclerosis (ALS) and in 11 neurologically normal controls. GDH activity was considerably increased in lateral and ventral white matter and in the dorsal horn of the ALS cervical spinal cord, but normal in the ventral horn and the dorsal columns. Similar, although less pronounced, GDH changes were found in the lumbar enlargement. The mean concentrations of aspartate and glutamate were reduced in all regions of ALS spinal cord investigated. Taurine concentrations were significantly increased in several subdivisions of cervical spinal cord, but normal in lumbar regions. Glycine levels were significantly reduced in lumbar ventral and dorsal horns. There was no striking change in spinal cord GABA levels in our ALS patients. It is suggested that the reduced levels of glutamate and aspartate as well as the elevated GDH activity in the spinal cord of ALS patients may reflect an overactivity of the neurons releasing these potentially excitotoxic amino acids and thus may be causally related to the spinal neuro-degenerative changes characteristic of ALS.     

Motor neurons are rich in non-phosphorylated neurofilaments: cross-species comparison and alterations in ALS

The localization and distribution of non-phosphorylated neurofilaments (NP-NF) in the upper and lower motor neurons was investigated in the rat, the common marmoset, the rhesus monkey and man using the SMI-32 antibody. Within the spinal cord of all species studied, the most intense NP-NF immunoreactivity was observed within the ventral horn alpha-motor neurons. Concurrent staining for the cholinergic marker choline acetyltransferase (ChAT) demonstrated that virtually all of the ChAT-positive alpha-motor neurons contain NP-NF immunoreactivity. Although NP-NF staining was also observed in other neurons within the ventral and intermediate horns, these neurons were loosely scattered and contained a considerably lower staining intensity. The only other prominent NP-NF staining in the spinal cord occurred within the neurons of the dorsal nucleus of Clark and the intermediolateral cell column. Phosphorylated neurofilament (P-NF) immunoreactivity was found primarily in neuronal processes. Occasionally, a solitary motor neuron contained weak P-NF immunoreactivity. Within the brainstem, neurons in all cranial nerve motor nuclei contained intense NP-NF immunoreactivity. The distribution and apparent density of NP-NF immunoreactive neurons in these nuclei was virtually identical to that observed for neurons immunoreactive for ChAT. NP-NF immunoreactive neurons of relatively lower intensity were found in many other regions of the brainstem. All of the giant Betz cells of layer (L) V in the motor cortex contained dark NP-NF immunoreactivity. Within the spinal cord of amyotrophic lateral sclerosis (ALS) patients, both Nissl and NP-NF staining demonstrated the dramatic loss of alpha-motor neurons characteristic of this disorder. Some of the remaining motor neurons contained intense P-NF immunoreactivity. These observations suggest that NP-NF immunoreactivity is a good marker for motor neurons in health and disease and may be a useful tool for studies of motor neuron degeneration (MND).     

14-3-3 proteins in Lewy body-like hyaline inclusions in patients with sporadic amyotrophic lateral sclerosis

14-3-3 proteins are highly conserved eukaryotic proteins that regulate various types of signal transduction pathways through phosphorylation-dependent protein-protein interactions. 14-3-3 mRNAs have been shown to be up-regulated in the injured rat motor neurons and in the spinal cords of patients with amyotrophic lateral sclerosis (ALS). To investigate the role of 14-3-3 proteins in ALS, we performed immunohistochemical studies on 14-3-3 using autopsied spinal cords from patients with sporadic ALS (sALS) and non-ALS subjects without spinal cord involvement. In the anterior horn of both groups, strong 14-3-3 immunoreactivity was observed in the somata and proximal processes of motor neurons. Many spheroids from all of the sALS cases were also immunopositive for 14-3-3. In addition, Lewy body-like hyaline inclusions (LBHIs), which were present in some sALS cases, were intensely immunostained. Our findings suggest that even in the severely affected anterior horn of patients with sALS, remaining motor neurons may contain abundant 14-3-3 proteins, and that 14-3-3 proteins may be partly associated with the pathogenesis of sALS, in particular with the formation of LBHIs.     

Pathological study of the diffuse myelin pallor in the anterolateral columns of the spinal cord in amyotrophic lateral sclerosis

An immunohistochemical study using a monoclonal antibody against macrophage (Ki-M1p) was performed to examine which fiber tracts are affected in the spinal cords and brainstems of ALS patients. In 21 out of 30 ALS patients, various degrees of macrophage infiltration were observed diffusely in the anterolateral columns beyond the corticospinal tracts. On the other hand, a few macrophages were scattered in 20 non-ALS patients in the anterolateral columns outside the corticospinal tracts. In ALS brainstems, the macrophages were mainly localized in the corticospinal tracts. The result suggests that the diffuse myelin pallor in the anterolateral columns beyond the corticospinal tracts may be derived from intrinsic spinal cord lesions. Quantitative investigation using a monoclonal antibody against phosphorylated neurofilaments (SMI-31) revealed that the decrease in the numbers of small fibers would induce the diffuse myelin pallor in anterolateral columns of ALS patients. From these findings, we propose that the propriospinal bundles are candidates for the degenerating fibers in the anterolateral columns of ALS.     

Altered in-vitro and in-vivo expression of glial glutamate transporter-1 following exposure to cerebrospinal fluid of amyotrophic lateral sclerosis patients

Our earlier studies have shown that cerebrospinal fluid (CSF) of amyotrophic lateral sclerosis (ALS) patients causes death of motor neurons, both in in-vitro as well as in-vivo. There was an aberrant phosphorylation of neurofilaments in cultured spinal cord neurons of chick and rats following exposure to CSF of ALS patients (ALS-CSF). Other features of neurodegeneration, such as swollen neuronal soma and beading of neurites were also observed. In neonatal rat pups exposed to ALS-CSF, we observed phosphorylated neurofilaments in the soma of spinal motor neurons in addition to the increased lactate dehydrogenase activity and reactive astrogliosis. The present study examines the effect of ALS-CSF on the expression of glial glutamate transporter (GLT-1) in embryonic rat spinal cord cultures as well as in spinal astrocytes of neonatal rats. Immunostaining suggested a decrease in the expression of GLT-1 by astrocytes both in culture and in-vivo following exposure to ALS-CSF. Quantification of Western blots confirmed the decreased expression of GLT-1. Our results provide evidence that toxic factor(s) present in ALS-CSF depletes GLT-1 expression. This could lead to an increased level of glutamate in the synaptic pool causing excitotoxicity to motor neurons, possibly by triggering the 'glutamate-mediated toxicity-pathway'.     

Subcellular distribution of delta-opioid receptors in the rat spinal cord: an approach using a three-dimensional reconstruction of confocal series of immunolabelled neurons

Using a specific rat monoclonal anti-idiotypic antibody we have examined the subcellular distribution of -opioid receptors in various neuronal subtypes of the rat spinal cord. The immunofluorescence was detected with a confocal microscope and in some cases serial images were processed for a three-dimensional (3-D) reconstruction of the neurons. Immunolabelling was found to be distributed throughout the spinal cord grey matter specially in the most superficial layers of the dorsal horn, around the central canal and in the region of motoneurons of the ventral horn. The 3-D reconstruction made on large neurons of lamina IX in the ventral horn and on neurons of lamina X around the central canal allowed the visualization of 5 -opioid receptors in the cytoplasm of the soma and proximal neurites of immunofluorescent neurons. Some immunolabelled receptors were also detected at the level of the plasma membrane of the cell bodies and in the nuclear matrix. Interestingly, a particular arrangement of delta-opioid receptors organized along parallel alignments was observed on the plasma membrane of some neurons. This study emphasizes the potential usefulness of a 3-D reconstruction in the study of the spatial arrangement of cellular components.     

Localization of the Serotonin Transporter in Rat Spinal Cord

The spinal cord is richly innervated by serotoninergic fibres originating from the raphe nuclei. The localization of the terminating component of serotoninergic neurotransmission, the serotonin transporter SERT1, was found in both the dorsal and ventral horns, especially at the level of the cervical and lumbar segments. Within the thoracic region, we observed a heavily labelled bundle in the intermediolateral nucleus of lamina VII. A low density of stained fibres was encountered in the sacral spinal cord. In contrast to homogeneous staining of motor nuclei, a differential labelling of laminae was seen in the dorsal horn, with laminae I, III and IV exhibiting a higher density of immunopositive terminals than the medial part of lamina II. High magnification revealed a preferential accumulation of serotonin transporter staining within nerve endings and varicosities of thin fibres. Double immunofluorescence staining demonstrated a co-localization of serotonin and its uptake system within these varicosities. These results show that the serotonin transporter is highly expressed in the rat spinal cord and that its distribution parallels the serotoninergic innervation. They also reinforce the view that varicosities are important neuronal structures, which modulate the function of dorsal and ventral horn neurons by releasing serotonin.     

Protein‐bound crotonaldehyde accumulates in the spinal cord of superoxide dismutase‐1 mutation‐associated familial amyotrophic lateral sclerosis and its transgenic mouse model

Growing evidence documents oxidative stress involvement in ALS. We previously demonstrated accumulation of a protein‐bound form of the highly toxic lipid peroxidation product crotonaldehyde (CRA) in the spinal cord of sporadic ALS patients. In the present study, to the determine the role for CRA in the disease processes of superoxide dismutase‐1 (SOD1) mutation‐associated familial ALS (FALS), we performed immunohistochemical and semiquantitative cell count analyses of protein‐bound CRA (P‐CRA) in the spinal cord of SOD1‐mutated FALS and its transgenic mouse model. Immunohistochemical analysis revealed increased P‐CRA immunoreactivity in the spinal cord of the FALS patients and the transgenic mice compared to their respective controls. In the FALS patients, P‐CRA immunoreactivity was localized in almost all of the chromatolytic motor neurons, neurofilamentous conglomerates, spheroids, cordlike swollen axons, reactive astrocytes and microglia, and the surrounding neuropil in the affected areas represented by the anterior horns. In the transgenic mice, P‐CRA immunoreactivity was localized in only a few ventral horn glia in the presymptomatic stage, in almost all of the vacuolated motor neurons and cordlike swollen axons and some of the ventral horn reactive astrocytes and microglia in the onset stage, and in many of the ventral horn reactive astrocytes and microglia in the advanced stage. Cell count analysis on mouse spinal cord sections disclosed a statistically significant increase in the density of P‐CRA‐immunoreactive glia in the ventral horns of the young to old G93A mice compared to the age‐matched control mice. The present results indicate that enhanced CRA formation occurs in motor neurons and reactive glia in the spinal cord of SOD1‐mutated FALS and its transgenic mouse model as well as sporadic ALS, suggesting implications for CRA in the pathomechanism common to these forms of ALS.     

Expression of metabotropic glutamate receptor mRNAs in the human spinal cord: implications for selective vulnerability of spinal motor neurons in amyotrophic lateral sclerosis

To elucidate the relevance of metabotropic glutamate receptors (mGluRs) to the selective vulnerability of motor neurons in the spinal cord in patients with amyotrophic lateral sclerosis (ALS), we investigated the distribution of mRNAs coding mGluR1-5 in the normal human spinal cord. The mRNAs for mGluR1, 4 and 5 were observed in the spinal gray matter, whereas mGluR2 mRNA was absent in the spinal cord and mGluR3 mRNA was displayed only on glial cells in the white matter. Signals for mGluR1 and mGluR5 were enriched in the dorsal horn, while mGluR4 mRNA was abundant in the ventral horn. Since agonists to group I mGluRs (mGluR 1 and 5) have been demonstrated to have neuroprotective effects on spinal motor neurons, less expression of mRNAs coding mGluR1 and mGluR5 in the ventral horn than in the dorsal horn may be implicated in the selective susceptibility of spinal motor neurons in ALS.     

PACAP mRNA is expressed in rat spinal cord neurons

This study examines the expression of pituitary adenylate cyclase activating polypeptide (PACAP) mRNA in the rat spinal cord during normal conditions and in response to sciatic nerve transection. Previously, PACAP immunoreactivity has been found in fibers in the spinal cord dorsal horn and around the central canal and in neurons in the intermediolateral column (IML). Furthermore, in the dorsal root ganglia, PACAP immunoreactivity and PACAP mRNA expression have been observed preferentially in nerve cell bodies of smaller diameter terminating in the superficial laminae of the dorsal horn. However, neuronal expression of PACAP mRNA in adult rat spinal cord appeared limited to neurons of the IML. By using a refined in situ hybridization protocol, we now detect PACAP mRNA expression in neurons primarily in laminae I and II, but also in deeper laminae of the spinal cord dorsal horn and around the central canal. In addition, PACAP mRNA expression is observed in a few neurons in the ventral horn. PACAP expression in the ventral horn is increased in a population of large neurons, most likely motor neurons, both after distal and proximal sciatic nerve transection. The proposed role of PACAP in nociception is strengthened by our findings of PACAP mRNA-expressing neurons in the superficial laminae of the dorsal horn. Furthermore, increased expression of PACAP in ventral horn neurons, in response to nerve transection, suggests a role for PACAP in repair/regeneration of motor neurons.     

Ubiquitin-immunoreactive filamentous inclusions in anterior horn cells of Guamanian and non-Guamanian amyotrophic lateral sclerosis

Summary Immunohistochemical studies with an antibody to ubiquitin revealed the presence of filamentous inclusions in spinal anterior horn cells in all of six patients with Guamanian amyotrophic lateral sclerosis (ALS) and one of six cases of parkinsonism-dementia complex (PD) on Guam. Similar ubiquitin-reactive filamentous inclusions were found in all of seven non-Guamanian sporadic ALS patients examined. No similar inclusions were seen in six normal controls or in non-ALS patients who had chromatolytic neurons. The filamentous inclusions differed from spinal neurofibrillary tangles, a characteristic feature of Guamanian ALS and PD, since they were restricted to anterior horn cells and did not react with anti-tau antibody. The chromatolytic neurons of non-ALS patients occasionally had weak diffuse immunoreactivity, but no focal inclusions were detected. These results suggest that ubiquitin-reactive focal filamentous inclusions may reflect a characteristic degenerative process of anterior horn cells of motor neuron disease.     

Phosphorylated high molecular weight neurofilament protein in the peripheral motor,sensory and sympathetic neuronal perikarya: system-dependent normal variations and changes in amyotrophic lateral sclerosis and multiple system atrophy

Summary Using monoclonal antibody (Ta-51) that specifically binds phosphorylated high molecular weight neurofilament (pNFH) proteins, we investigated the occurrence of perikaryal pNFH in the spinal ventral horn motoneurons, intermediolateral column (ILC) neurons, sympathetic ganglion neurons and dorsal root ganglion (DRG) neurons obtained from patients with amyotrophic lateral sclerosis (ALS) and multiple system atrophy (MSA) and from control cases. In the controls, a system-dependent variation in perikaryal Ta-51 immunoreactivity was observed. Very few ventral horn cells and ILC neurons were stained with Ta-51, while large population of DRG neurons and sympathetic neurons were Ta-51 positive. The incidence of perikaryal immunoreactivity in the ventral horn cells was significantly increased in ALS and MSA. Some ILC neurons in ALS were Ta-51 positive and their incidence was significantly higher than that of the controls. These data suggest that both ILC neurons and ventral horn cells are affected with respect to pNFH metabolism in ALS and MSA. No significant difference was, however, detected in the Ta-51 immunoreactivity of both DRG and sympathetic ganglion neurons in ALS and MSA as compared with the controls.Supported by grants from the Japanese Ministry of Welfare and Health     

Comparison of phosphorylated TDP-43-positive inclusions in oculomotor neurons in patients with non-ALS and ALS disorders

TDP-43 has been identified as a major component of the pathological inclusions in most forms of frontotemporal lobar degeneration with ubiquitin-positive inclusions and in amyotrophic lateral sclerosis (ALS). In the present study, paraffin sections of the midbrain in 112 patients with various non-ALS disorders and 27 patients with sporadic ALS were immunostained with antibody against phosphorylated TDP-43 (pTDP-43). pTDP-43-positive inclusions in oculomotor neurons were detected in 18 of 112 patients with non-ALS disorders (16.1%). The appearance of the inclusions showed fine filamentous structures rather than the skein-like inclusions seen in the anterior horn cells of ALS spinal cords. The incidence was increased in the age range of 80-89 years old (10/37 cases; 27.0%), in which 6 of 10 cases demonstrated AD pathology in the temporal lobes. Twenty-seven ALS patients were examined and the findings were compared with those of non-ALS patients. There were 13 cases demonstrating pTDP-43-positive inclusions (48.1%) which showed stronger immunoreactivities in ALS cases. This is the first report demonstrating fine filamentous pTDP-43-positive inclusions in oculomotor neurons in non-ALS disorders. Although the mechanisms underlying pTDP-43 in oculomotor neurons are currently unknown, its detection is of interest, and the expression may occur not only in ALS but also during the aging process.