Zen Kobayashi

Phosphorylated and cleaved TDP-43 in ALS, FTLD and other neurodegenerative disorders and in cellular models of TDP-43 proteinopathy.

Transactivation response (TAR) DNA‐binding protein of Mr 43 kDa (TDP‐43) is a major component of the tau‐negative and ubiquitin‐positive inclusions that characterize amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration which is now referred to as FTLD‐TDP. Concurrent TDP‐43 pathology has been reported in a variety of other neurodegenerative disorders such as Alzheimers disease, forming a group of TDP‐43 proteinopathy. Accumulated TDP‐43 is characterized by phosphorylation and fragmentation. There is a close relationship between the pathological subtypes of FTLD‐TDP and the immunoblot pattern of the C‐terminal fragments of phosphorylated TDP‐43. These results suggest that proteolytic processing of accumulated TDP‐43 may play an important role for the pathological process. In cultured cells, transfected C‐terminal fragments of TDP‐43 are more prone to form aggregates than full‐length TDP‐43. Transfecting the C‐terminal fragment of TDP‐43 harboring pathogenic mutations of TDP‐43 gene identified in familial and sporadic ALS cases into cells enhanced the aggregate formation. Furthermore, we found that methylene blue and dimebon inhibit aggregation of TDP‐43 in these cellular models. Understanding the mechanism of phosphorylation and truncation of TDP‐43 and aggregate formation may be crucial for clarifying the pathogenesis of TDP‐43 proteinopathy and for developing useful therapeutics.

Intractable hiccup caused by medulla oblongata lesions: A study of an autopsy patient with possible neuromyelitis optica

We report the first autopsy verification of medulla oblongata lesions involving bilateral nucleus tractus solitarius (NTS) as a cause of intractable hiccup in an autopsy patient. The female patient first developed pain and weakness in the lower limbs and urinary incontinence at age 48, and was given a diagnosis of myelitis. Intractable hiccup was accompanied by urinary retention on the third attack. She died of respiratory failure when the fifth attack occurred at age 51. Autopsy disclosed severe involvement of the medulla oblongata and entire spinal cord. Optic nerve lesions were also identified unexpectedly. Dual involvement of the optic nerve and spinal cord, necrotic spinal cord lesions involving not only myelin but also neurons and axon, and marked extension of the spinal cord lesions in both the longitudinal and transverse directions suggested the diagnosis of neuromyelitis optica rather than multiple sclerosis. Although animal experiments have shown that NTS is a critical structure in the hiccup reflex, we demonstrated for the first time the involvement of the NTS in an autopsy patient with intractable hiccup.

FUS/TLS-immunoreactive neuronal and glial cell inclusions increase with disease duration in familial amyotrophic lateral sclerosis with an R521C FUS/TLS mutation.

Abstract Basophilic inclusions (BIs) are pathological features of a subset offrontotemporal lobar degeneration disorders, including sporadic amyotrophic lateral sclerosis (ALS) and familial ALS (FALS). Mutations in the fused in sarcoma/translocated in liposarcoma (FUS/TLS) gene have recently been identified as a cause of FALS. The FUS/TLS-immunoreactive inclusions are consistently found in cases of frontotemporal lobar degeneration with BIs; however, the association between ALS cases with BIs and FUS/TLS accumulation is not well understood. We used immunohistochemistry to analyze 3 autopsy cases of FALS with the FUS/TLS mutation and with BIs using anti-FUS/TLS antibodies. The disease durations were 1, 3, and 9 years. As the disease duration becomes longer, there were broader distributions of neuronal and glial FUS/TLS-immunoreactive inclusions. As early as 1 year after the onset, BIs, neuronal cytoplasmic inclusions and glial cytoplasmic inclusions were found in the substantia nigra in addition to the anterior horn of the spinal cord. Glial cytoplasmic inclusions are found earlier and in a wider distribution than neuronal cytoplasmic inclusions. The distribution of FUS/TLS-immunoreactive inclusions in FUS/TLS-mutated FALS with BIs was broader than that of BIs alone, suggesting that the pathogenetic mechanism may have originated from the FUS/TLS proteinopathy.

Occurrence of basophilic inclusions and FUS-immunoreactive neuronal and glial inclusions in a case of familial amyotrophic lateral sclerosis

Basophilic inclusions (BIs) are the pathological feature in a subset of frontotemporal lobar degeneration (FTLD), sporadic amyotrophic lateral sclerosis (SALS) and familial ALS (FALS) cases. Mutations in the fused in sarcoma (FUS) gene have been recently identified as the cause of FALS type 6. FUS-immunoreactive (ir) inclusions are consistently found in cases of FTLD with BIs, but the association between ALS cases with BIs and FUS accumulation is still not well understood. In this study, we immunohistochemically analyzed the autopsied case of FALS with BIs using anti-FUS antibodies. The case was a 42-year-old woman who developed proximal weakness of the bilateral upper limbs, followed by weakness of other parts including the bulbar regions, and died at age 45. Since this case is a member of a family with FALS harboring the R521C mutation of the FUS gene, she may have carried the same FUS mutation. Histopathologically, neuronal loss was evident in the motor system and other areas including the cuneate nucleus of the medulla oblongata. BIs appeared in the brain stem, cerebellum and anterior horn of the lumbar cord. FUS-ir neuronal cytoplasmic inclusions, glial cytoplasmic inclusions and dystrophic neurites were more abundantly and widely occurring than BIs, especially in the cuneate nucleus and globus pallidus. These findings support the idea that both BIs and FUS-ir structures are pathological hallmarks of a subset of ALS cases.

Clinicopathological characteristics of FTLD-TDP showing corticospinal tract degeneration but lacking lower motor neuron loss

The presence of frontotemporal lobar degeneration with TDP-43-positive inclusions (FTLD-TDP) showing corticospinal tract (CST) degeneration but lacking lower motor neuron (LMN) loss has been reported, and the term primary lateral sclerosis (PLS) is used to distinguish motor neuron disease (MND) of these cases from amyotrophic lateral sclerosis (ALS). To date, however, details of clinicopathological findings of FTLD-MND-PLS type (FTLD-MND-P) have not been reported. We evaluated medical records and histopathological findings of ten cases of FTLD-MND-P, in comparison with those of six FTLD-MND-ALS type (FTLD-MND-A) cases. The mean age at onset and disease duration of FTLD-MND-P cases were 54 and 12 years, respectively. The first symptoms were frontotemporal dementia showing behavioral abnormality and/or personality change in five cases, semantic dementia in three cases, progressive non-fluent aphasia in one case, and auditory hallucination in one case. Upper motor neuron signs were clinically identified in six of the ten cases. There were no LMN signs throughout the clinical course in any case. Histopathologically, there was no obvious LMN loss or Bunina bodies in the hypoglossal nucleus or spinal cord in any case, whereas the CST was involved in all cases. The cerebral cortex of the six cases showed type 1 of TDP-43 histology defined by Cairns et al., whereas three cases showed type 3 histology, and one case showed type 2 histology. In all cases, TDP-43 positive neuronal cytoplasmic inclusions were absent or rare in the LMNs, while TDP-43 positive round structures were frequently identified in the neuropil of the spinal cord anterior horn in some cases. This study clarified that FTLD-MND-P cases have characteristic clinicopathological features distinct from those of FTLD-MND-A.

Failure of mefloquine therapy in progressive multifocal leukoencephalopathy: report of two Japanese patients without human immunodeficiency virus infection.

Although progressive multifocal leukoencephalopathy (PML) cases showing responses to mefloquine therapy have been reported, the efficacy of mefloquine for PML remains unclear. We report on the failure of mefloquine therapy in two Japanese patients with PML unrelated to human immunodeficiency virus. One of the patients was a 47-year-old male who had been treated with chemotherapy for Waldenström macroglobulinemia, and the other was an 81-year-old male with idiopathic CD4(+) lymphocytopenia. Diagnosis of PML was established based on MRI findings and increased JC virus DNA in the cerebrospinal fluid in both patients. Mefloquine was initiated about 5 months and 2 months after the onset of PML, respectively. During mefloquine therapy, clinical and radiological progression was observed, and JC virus DNA in the cerebrospinal fluid was increased in both patients. Both patients died about 4 months and 2 months after initiation of mefloquine, respectively. Further studies are necessary to clarify the differences between mefloquine responders and non-responders in PML.

FALS with Gly72Ser mutation in SOD1 gene: Report of a family including the first autopsy case

Clinical information on familial amyotrophic lateral sclerosis (FALS) with Gly72Ser mutation in the Cu/Zn superoxide dismutase-1 (SOD1) gene has been limited and autopsy findings remain to be clarified. We describe one Japanese family with ALS carrying Gly72Ser mutation in the SOD1 gene, in which autopsy was performed on one affected member. The autopsied female patient developed muscle weakness of the left thigh at age 66 and showed transient upper motor neuron signs. She died of respiratory failure 13 months after onset without artificial respiratory support. There were no symptoms suggesting bladder or rectal dysfunction throughout the clinical course. Her brother with ALS was shown to have Gly72Ser mutation in the SOD1 gene. Histopathologically, motor neurons were markedly decreased throughout the whole spinal cord, whereas corticospinal tract involvement was very mild and was demonstrated only by CD68 immunohistochemistry. Degeneration was evident in the posterior funiculus, Clarkes nucleus, posterior cerebellar tract, and Onufs nucleus. Neuronal hyaline inclusions were rarely observed in the neurons of the spinal cord anterior horn including Onufs nucleus, and were immunoreactive for SOD1. To date, neuron loss in Onufs nucleus has hardly been seen in ALS, except in the patients showing prolonged disease duration with artificial respiratory support. Involvement of Onufs nucleus may be a characteristic pathological feature in FALS with Gly72Ser mutation in the SOD1 gene.

Gray matter lesions in Nasu-Hakola disease: A report on three autopsy cases

Nasu‐Hakola disease is an autosomal recessively inherited disease characterized by lipomembranous polycystic osteodysplasia and sclerosing leukoencephalopathy. While white matter lesions prominent in the brain have been reported in the literature, gray matter lesions have not received particular attention. In this study, we examined three autopsy cases of Nasu‐Hakola disease in order to focus specifically on gray matter lesions. The ages at onset of the three cases were 20, 23 and 29 years, and the disease durations were 29, 19 and 8 years, respectively. In addition to characteristic degeneration in the cerebral white matter, such as demyelination with conspicuous fibrillary gliosis and axonal changes, all three cases showed overt pathology in the gray matter. Neuronal loss with gliosis in the thalamus (particularly in the dorsomedial nucleus and anterior nucleus), caudate nucleus, putamen and substantia nigra was prominent in all cases, and the severity corresponded to the disease duration. The cerebral cortices were relatively preserved in all cases. One case showed neuronal loss and gliosis in the gray matter of the hippocampus, possibly due to repeated episodes of epileptic convulsions. These gray matter pathologies are considered to be responsible for some of the clinical manifestations of the disease, including extrapyramidal symptoms.

Pseudopolyneuritic form of ALS revisited: Clinical and pathological heterogeneity

Pseudopolyneuritic form of ALS is a subtype of ALS characterized by distal weakness of the unilateral lower limb and absence of Achilles tendon reflex (ATR) at disease onset. Recognition of this form of ALS is important for clinicians because the combination of distal weakness of the lower limb and absence of ATR usually suggests peripheral neuropathy. We reviewed the clinical records of 42 autopsy‐proven sporadic ALS cases and found three cases that showed onset of weakness of the unilateral lower limb with distal dominance and absence of ATR. The disease duration in the three cases was 2, 3 and 19 years, respectively. The clinical features of the patient with a course of 19 years had been restricted to lower motor neuron signs. Histopathologically, consistent findings in the three cases were severe motor neuron loss throughout the whole spinal cord, with relative preservation of the hypoglossal nucleus. Reflecting this finding, TDP‐43‐positive neuronal cytoplasmic inclusions in the spinal cord were sparse in two cases, and absent in a third. In the patient showing a clinical course of 19 years, mild corticospinal tract degeneration appeared to correspond to the absence of upper motor neuron signs and prolonged disease duration. In this case only, Bunina bodies were not demonstrated. In this study, we clarified the clinical and pathological heterogeneity of this form of ALS.

Frontotemporal lobar degeneration with motor neuron disease showing severe and circumscribed atrophy of anterior temporal lobes.

Frontotemporal lobar degeneration (FTLD) is characterized by a variety of behavioral and psychiatric symptoms based on the dysfunction of frontal and/or temporal lobes. A 63-year-old Japanese man without a family history of neurological diseases developed progressive symptoms of frontotemporal dementia, followed by motor neuron disease (MND). Brain magnetic resonance images demonstrated severe atrophy in the anterior temporal lobes from early clinical stage. The symptoms got rapidly worsened and the patient died of respiratory failure 1year 8months after the disease onset. A postmortem study revealed severe and circumscribed atrophy in the anterior temporal lobes, and histological examination disclosed marked neuronal loss with many neuronal cytoplasmic inclusions which were immunoreactive for ubiquitin antibodies and phosphorylated TAR DNA-binding protein of 43kDa (TDP-43) antibodies in hippocampal dentate granule cells and amygdalae, as well as a few neuronal cytoplasmic inclusions without dystrophic neurites in the temporal neocortex. This case report showed typical features of FTLD-MND in clinical course and TDP-43 pathology with unusual severity and distribution of cerebral atrophy, suggesting a unique manifestation of FTLD-MND.