Fumiaki Mori

Involvement of the peripheral nervous system in synucleinopathies, tauopathies and other neurodegenerative proteinopathies of the brain

Involvement of the peripheral nervous system (PNS) is relatively common in some neurodegenerative proteinopathies of the brain and may be pathogenetically and diagnostically important. In Parkinson’s disease, neuronal α-synuclein aggregates are distributed throughout the nervous system, including the central nervous system (CNS), sympathetic ganglia, enteric nervous system, cardiac and pelvic plexuses, submandibular gland, adrenal medulla and skin. The pathological process may target the PNS and CNS at the same time. In multiple system atrophy, numerous glial cytoplasmic inclusions composed of filamentous α-synuclein are widely distributed in the CNS, while α-synuclein accumulation is minimal in the sympathetic ganglia and is restricted to neurons. Neurofibrillary tangles can occur in the sympathetic and spinal ganglia in tauopathy, although they appear to develop independently of cerebral Alzheimer’s disease pathology. In amyotrophic lateral sclerosis, neuronal loss with TDP-43-positive neuronal cytoplasmic inclusions in the spinal ganglia is more frequent than previously thought. Peripheral ganglia and visceral organs are also involved in polyglutamine diseases. Further elucidation and characterization of PNS lesions will have implications for intravital biopsy diagnosis in neurodegenerative proteinopathy, particularly in Parkinson’s disease.

Maturation process of TDP-43-positive neuronal cytoplasmic inclusions in amyotrophic lateral sclerosis with and without dementia

To elucidate the maturation process of TDP-43-positive neuronal inclusions, we immunohistochemically and immunoelectron-microscopically examined multiple areas from the brain and spinal cord from ten patients with amyotrophic lateral sclerosis (ALS) and 25 control subjects. TDP-43 immunohistochemistry demonstrated three types of inclusions in ALS: skein-like, round, and dot-like inclusions. Skein-like inclusions were found in all cases of ALS. Dot-like inclusions were found in the anterior horn in seven cases of ALS, all of whom had round inclusions, but not in cases without round inclusions. In addition, careful examination revealed two types of diffuse punctate cytoplasmic staining: linear wisps and punctate granules. Linear wisps were present in all cases of ALS but in none of 25 controls. In contrast, punctate granules were detected in all cases of ALS as well as in five of 13 normal and in seven of 12 diseased controls. Immunoelectron-microscopy revealed that skein-like inclusions consisted of granule-associated parallel filaments. Round and dot-like inclusions were composed of granulo-filamentous structures. However, punctate granules corresponded to the mitochondria and were not immunostained with anti-ubiquitin, indicating that punctate granules represent cross-reaction. We assumed that linear wisps (“fine skein”) aggregate as thicker and longer threads (“coarse skein”), whereas round inclusions arise from dot-like inclusions. These findings suggest that there are differences in the formation process between skein-like and round inclusions, despite the antigenic and ultrastructural similarities.

TDP-43-immunoreactive neuronal and glial inclusions in the neostriatum in amyotrophic lateral sclerosis with and without dementia

TDP-43 is a major component of ubiquitin-positive, tau-negative inclusions in amyotrophic lateral sclerosis (ALS), and frontotemporal lobar degeneration. We immunohistochemically examined the neostriatum from 14 cases of classic ALS (cALS), six cases of ALS with dementia (ALS-D), and 20 control subjects. TDP-43-positive, crescent or circular inclusions were found in neostriatal small neurons in 19 of 20 cases of ALS, but not in controls. Two types of inclusions were found in the large neurons: ubiquitin-positive, TDP-43-negative rod-like inclusions, and ubiquitin- and TDP-43-positive pleomorphic inclusions. The latter were specific to ALS; they were found in seven cases of cALS and in all of ALS-D. TDP-43-positive glial inclusions were also found in 12 cases of cALS and in all of ALS-D. These TDP-43-positive neuronal and glial inclusions were more numerous in ALS-D than cALS. In ALS-D, neuronal loss in the substantia nigra was found in all the cases, whereas mild gliosis without obvious neuronal loss was noted in the neostriaum in only two cases. These findings suggest that the neostriatum is also involved in the disease process of ALS with and without dementia.

Rats Harboring S284L Chrna4 Mutation Show Attenuation of Synaptic and Extrasynaptic GABAergic Transmission and Exhibit the Nocturnal Frontal Lobe Epilepsy Phenotype

Mutations of genes encoding α4, β2, or α2 subunits (CHRNA4, CHRNB2, or CHRNA2, respectively) of nAChR [neuronal nicotinic ACh (acetylcholine) receptor] cause nocturnal frontal lobe epilepsy (NFLE) in human. NFLE-related seizures are seen exclusively during sleep and are characterized by three distinct seizure phenotypes: “paroxysmal arousals,” “paroxysmal dystonia,” and “episodic wandering.” We generated transgenic rat strains that harbor a missense mutation S284L, which had been identified in CHRNA4 in NFLE. The transgenic rats were free of biological abnormalities, such as dysmorphology in the CNS, and behavioral abnormalities. The mRNA level of the transgene (mutant Chrna4) was similar to the wild type, and no distorted expression was detected in the brain. However, the transgenic rats showed epileptic seizure phenotypes during slow-wave sleep (SWS) similar to those in NFLE exhibiting three characteristic seizure phenotypes and thus fulfilled the diagnostic criteria of human NFLE. The therapeutic response of these rats to conventional antiepileptic drugs also resembled that of NFLE patients with the S284L mutation. The rats exhibited two major abnormalities in neurotransmission: (1) attenuation of synaptic and extrasynaptic GABAergic transmission and (2) abnormal glutamate release during SWS. The currently available genetically engineered animal models of epilepsy are limited to mice; thus, our transgenic rats offer another dimension to the epilepsy research field.

TRIM9, a novel brain-specific E3 ubiquitin ligase, is repressed in the brain of Parkinson’s disease and dementia with Lewy bodies

TRIM family proteins are involved in a broad range of biological processes, and their alteration results in many diverse pathological conditions found in genetic diseases, viral infections, and cancers. However, the spatial and temporal expression and function of TRIM9, one of TRIM family proteins, remain obscure. Our results here showed that TRIM9 protein is mainly expressed in the cerebral cortex, and functions as an E3 ubiquitin ligase collaborating with an E2 ubiquitin conjugating enzyme UbcH5b. Immunohistochemical examination revealed that TRIM9 is localized to the neurons in the normal mouse and human brain and that TRIM9 immunoreactivity is severely decreased in the affected brain areas in Parkinsons disease and dementia with Lewy bodies. This repressed level of TRIM9 protein was supported by immunoblotting analysis. Intriguingly, cortical and brainstem-type Lewy bodies were immunopositive for TRIM9. These results suggest that TRIM9 plays an important role in the regulation of neuronal functions and participates in pathological process of Lewy body disease through its ligase activity.

Epitope mapping of 2E2-D3, a monoclonal antibody directed against human TDP-43

TDP-43 is now known to be a major component of ubiquitin-positive, tau-negative inclusions in frontotemporal lobar degeneration with ubiquitin-positive inclusions and sporadic amyotrophic lateral sclerosis. In this study, we mapped the epitope for the monoclonal anti-TDP-43 antibody 2E2-D3. Our mapping and peptide competition experiments showed that the antibody reacted with human TDP-43, but not mouse or rat TDP-43, and recognized amino acids 205-222 of human TDP-43, corresponding to a part of the second RNA recognition motif. These findings suggest that 2E2-D3 is a useful antibody for the characterization of mouse lines transgenic for human TDP-43.

Decreased cystatin C immunoreactivity in spinal motor neurons and astrocytes in amyotrophic lateral sclerosis.

Cystatin C (CC), a cysteine protease inhibitor involved in protein degradation, is a marker of Bunina bodies in lower motor neurons in amyotrophic lateral sclerosis (ALS). TAR-DNA binding protein-43 (TDP-43)-immunoreactive inclusions are also histological hallmarks of ALS but whether CC is found in motor neurons with or without TDP-43-positive inclusions in ALS is not known. To determine whether inclusion body formation affects cytoplasmic CC immunoreactivity, we examined spinal cords from 9 ALS patients and 12 control subjects by immunohistochemistry. Most anterior horn cells (AHCs) showed moderate to intense immunoreactivity in controls, whereas CC immunoreactivity was markedly decreased in AHCs in ALS cases. The proportion of CC-immunolabeled AHCs was reduced regardless of whether they contained Bunina bodies. In contrast, the proportion of CC-immunolabeled AHCs was significantly reduced in those with TDP-43 inclusions. Cystatin C immunoreactivity of astrocytes in the spinal gray matter and white matter in ALS was significantly decreased compared with controls. These findings suggest that the formation of TDP-43 inclusions, but not of Bunina bodies, may be linked to the content of CC in spinal motor neurons and that perturbations in endogenous levels of CC in neuronal and glial cells may be part of the neurodegenerative processes in ALS.

Incipient intranuclear inclusion body disease in a 78‐year‐old woman

We report an incipient case of intranuclear inclusion body disease (INIBD) in a 78‐year‐old woman. No apparent neurological symptoms were noticed during the clinical course. Post mortem examination revealed widespread occurrence of eosinophilic intranuclear inclusions in neuronal and glial cells of the central and peripheral nervous systems, as well as in parenchymal cells of the visceral organs. The inclusions were observed more frequently in glial cells than in neuronal cells. Ultrastructurally, the inclusions consisted of granular and filamentous material. Immunohistochemically, the inclusions were positive for ubiquitin, ubiquitin‐related proteins (NEDD8 ultimate buster 1, small ubiquitin modifier‐1, small ubiquitin modifier‐2 and p62), promyelocytic leukemia protein and abnormally expanded polyglutamine. Consistent with previous studies, the vast majority of inclusion‐bearing glial cells were astrocytes. Furthermore, p25α‐positive oligodendrocytes rarely contained intranuclear inclusions. These findings suggest that INIBD may occur in non‐demented elderly individuals and that oligodendrocyte is also involved in the disease process of INIBD.

Relationship between Bunina bodies and TDP-43 inclusions in spinal anterior horn in amyotrophic lateral sclerosis

F. Mori, K. Tanji, Y. Miki, A. Kakita, H. Takahashi and K. Wakabayashi (2010) Neuropathology and Applied Neurobiology36, 345–352u2028Relationship between Bunina bodies and TDP‐43 inclusions in spinal anterior horn in amyotrophic lateral sclerosis

Enhancement of native and phosphorylated TDP-43 immunoreactivity by proteinase K treatment following autoclave heating

TDP‐43 is a major disease protein in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration with TDP‐43 (FTLD‐TDP). To evaluate the effectiveness of proteinase K (PK) treatment in antigen retrieval for native and phosphorylated TDP‐43 protein, we examined the temporal cortex and spinal cord from patients with sporadic ALS and FTLD‐TDP and control subjects. PK treatment following heat retrieval enhanced the immunoreactivity for native TDP‐43 in controls as well as for native and phosphorylated TDP‐43 in ALS and FTLD‐TDP. A significant number of TDP‐43‐positive neuropil threads were demonstrated in lesions, in which routine immunohistochemistry revealed that the predominant inclusions are cytoplasmic. This retrieval method is the best of immunohistochemical techniques for demonstrating TDP‐43 pathology, especially in the neuropil.