Intranuclear Inclusion Body Disease Research Articles

Clinical Features and Classification of Neuronal Intranuclear Inclusion Disease.

Neuronal intranuclear inclusion body disease (NIID) is a neurodegenerative disease with highly heterogeneous clinical manifestations. The present study aimed to characterize clinical features and propose a classification system based on a large cohort of NIID in China. The Chinese NIID registry was launched from 2017, and participants' demographics and clinical features were recorded. Brain MRI, skin pathologies, and the number of GGC repeat expansions in the 5' untranslated region of the NOTCH2NLC gene were evaluated in all patients. In total, 223 patients (64.6% female) were recruited; the mean (SD) onset age was 56.7 (10.3) years. The most common manifestations were cognitive impairment (78.5%) and autonomic dysfunction (70.9%), followed by episodic symptoms (51.1%), movement disorders (50.7%), and muscle weakness (25.6%). Imaging markers included hyperintensity signals along the corticomedullary junction on diffusion-weighted imaging (96.6%), white matter lesions (98.1%), paravermis (55.0%), and focal cortical lesions (10.1%). The median size of the expanded GGC repeats in these patients was 115 (range, 70-525), with 2 patients carrying >300 GGC repeats. A larger number of GGC repeats was associated with younger age at onset (r = -0.329, p < 0.0001). According to the proposed clinical classification based on the most prominent manifestations, the patients were designated into 5 distinct types: cognitive impairment-dominant type (34.1%, n = 76), episodic neurogenic event-dominant type (32.3%, n = 72), movement disorder-dominant type (17.5%, n = 39), autonomic dysfunction-dominant type (8.5%, n = 19), and neuromuscular disease-dominant type (7.6%, n = 17). Notably, 32.3% of the episodic neurogenic event-dominant type of NIID has characteristic focal cortical lesions on brain MRI presenting localized cortical edema or atrophy. The mean onset age of the neuromuscular disease-dominant type was 47.2 (17.6) years, younger than the other types (p < 0.001). There was no significant difference in the sizes of GGC repeats among the patients in the 5 types (p = 0.547, Kruskal-Wallis test). This observational study of NIID establishes an overall picture of the disease regarding clinical, imaging, and genetic characteristics. The proposed clinical classification of NIID based on the most prominent manifestation divides patients into 5 types.

Immunohistochemical localization of exoribonucleases (DIS3L2 and XRN1) in intranuclear inclusion body disease.

mRNA turnover controls gene expression under various conditions in aging and neurodegenerative diseases. Polyglutamine (polyQ) diseases and intranuclear inclusion body disease (INIBD) are neurodegenerative diseases characterized by the formation of nuclear inclusions. These inclusions are immunopositive for several proteins associated with amyotrophic lateral sclerosis. In amyotrophic lateral sclerosis, the processing of RNA from gene transcription through degradation (RNA metabolism) has been reported to be altered. We hypothesized that the proteins associated with RNA metabolism are also involved in the formation of nuclear inclusions in polyQ diseases and INIBD. 3'-5' exoribonuclease DIS3L2 and 5'-3' exoribonuclease XRN1 play critical roles in mRNA decay. Using immunohistochemistry with antibodies against DIS3L2 and XRN1, we examined the brains of patients with polyQ diseases and INIBD and normal control subjects. In controls, immunoreactivity for DIS3L2 and XRN1 was found in the neuronal cytoplasm and neuropil, respectively. In INIBD, immunoreactivity for DIS3L2 and XRN1 was present in neuronal and glial nuclear inclusions. Co-localization of ubiquitin and DIS3L2 or XRN1 was demonstrated in these inclusions. In polyQ diseases, however, nuclear inclusions were immunonegative for DIS3L2 and XRN1. These findings suggest that sequestration of exoribonucleases to nuclear inclusions may be related to the pathogenesis of INIBD.

G protein-coupled receptor 26 immunoreactivity in intranuclear inclusions associated with polyglutamine and intranuclear inclusion body diseases.

G protein-coupled receptor 26 (GPR26) is one of the G-protein-coupled receptors (GPCRs), which comprise the largest family of membrane proteins and mediate most of the physiological responses to hormones, neurotransmitters and environmental stimulants. Although GPCRs are considered to play an important role in the pathophysiology of neurodegenerative disorders, it is uncertain whether GPR26 is involved in the pathogenesis of polyglutamine and intranuclear inclusion body diseases. We immunohistochemically examined the brain tissues of patients with four polyglutamine diseases (Huntington's disease, dentatorubral-pallidoluysian atrophy, and spinocerebellar ataxia types 1 and 3) and intranuclear inclusion body disease, and normal control subjects. In controls, anti-GPR26 antibody immunolabeled the neuronal cytoplasm in a diffuse granular pattern. Neuronal nuclear inclusions in polyglutamine diseases were immunopositive for GPR26. In intranuclear inclusion body disease, GPR26-positive nuclear inclusions were found in both neurons and glial cells. Marinesco bodies in aged control subjects were also positive for GPR26. Double immunofluorescence analysis revealed co-localization of GPR26 with polyglutamine or ubiquitin in these nuclear inclusions. These findings suggest that GPR26 may have a common role in the formation or degradation of intranuclear inclusions in several neurodegenerative diseases.

Accumulation of the sigma‐1 receptor is common to neuronal nuclear inclusions in various neurodegenerative diseases

The sigma-1 receptor (SIGMAR1) is now known to be one of the endoplasmic reticulum (ER) chaperones, which participate in the degradation of misfolded proteins in cells via the ER-related degradation machinery linked to the ubiquitin-proteasome pathway. Mutations of the SIGMAR1 gene are implicated in the pathogenesis of familial frontotemporal lobar degeneration and motor neuron disease. Involvement of ER dysfunction in the formation of inclusion bodies in various neurodegenerative diseases has also become evident. We performed immunohistochemical staining to clarify the localization of SIGMAR1 in the brains of patients with neurodegenerative disorders, including trans-activation response DNA protein 43 (TDP-43) proteinopathy, tauopathy, α-synucleinopathy, polyglutamine disease and intranuclear inclusion body disease (INIBD). Double-immunocytofluorescence and Western blot analyses of cultured cells were also performed to investigate the role of SIGMAR1 using a specific exportin 1 inhibitor, leptomycin B and an ER stress inducer, thapsigargin. SIGMAR1 was consistently shown to be co-localized with neuronal nuclear inclusions in TDP-43 proteinopathy, five polyglutamine diseases and INIBD, as well as in intranuclear Marinesco bodies in aged normal controls. Cytoplasmic inclusions in neurons and glial cells were unreactive for SIGMAR1. In cultured cells, immunocytofluorescent study showed that leptomycin B and thapsigargin were shown to sequester SIGMAR1 within the nucleus, acting together with p62. This finding was also supported by immunoblot analysis. These results indicate that SIGMAR1 might shuttle between the nucleus and the cytoplasm. Neurodegenerative diseases characterized by neuronal nuclear inclusions might utilize the ER-related degradation machinery as a common pathway for the degradation of aberrant proteins.

Valosin‐containing protein immunoreactivity in tauopathies, synucleinopathies, polyglutamine diseases and intranuclear inclusion body disease

Valosin-containing protein (VCP) is associated with multiple cellular functions, including ubiquitin-dependent protein degradation. Mutations in VCP are known to cause inclusion body myopathy with Paget's disease and frontotemporal dementia and familial amyotrophic lateral sclerosis (fALS; ALS14), both of which are characterized by trans-activation response DNA protein 43 (TDP-43)-positive neuronal cytoplasmic and nuclear inclusions. Recently, immunoreactivity for fALS-associated proteins (TDP-43, fused in sarcoma (FUS), optineurin and ubiquilin-2) were reported to be present in cytoplasmic and nuclear inclusions in various neurodegenerative diseases. However, the extent and frequency of VCP-immunoreactive structures in these neurodegenerative diseases are uncertain. We immunohistochemically examined the brains of 72 cases with neurodegenerative diseases and five control cases. VCP immunoreactivity was present in Lewy bodies in Parkinson's disease and dementia with Lewy bodies, and neuronal nuclear inclusions in five polyglutamine diseases and intranuclear inclusion body disease, as well as in Marinesco bodies in aged control subjects. However, other neuronal and glial cytoplasmic inclusions in tauopathies and TDP-43 proteinopathies were unstained. These findings suggest that VCP may have common mechanisms in the formation or degradation of cytoplasmic and nuclear inclusions of neurons, but not of glial cells, in several neurodegenerative conditions.

Autophagy-related proteins (p62, NBR1 and LC3) in intranuclear inclusions in neurodegenerative diseases

Incorporation of ubiquitin and ubiquitin-related proteins including p62 into neuronal intranuclear inclusions (NIIs) has been reported in a variety of neurodegenerative diseases. However, involvement of autophagy-specific proteins (NBR1 and LC3) in NIIs has not been mentioned. We immunohistochemically examined the brain of patients with Machado–Joseph disease (MJD; n=5), dentatorubral-pallidoluysian atrophy (DRPLA; n=5) and intranuclear inclusion body disease (INIBD; n=5), using antibodies against ubiquitin, p62, NBR1 and LC3. The proportion of p62-, NBR1- and LC3-positive inclusions relative to the number of ubiquitin-positive inclusions was calculated in each case. NIIs were positive for p62 in MJD (19.3%), DRPLA (49.7%) and INIBD (99.8%). As for autophagy-specific proteins, NIIs were positive for NBR1 in MJD (4.2%), DRPLA (5.5%) and INIBD (13.2%) and negative for LC3 in MJD, DRPLA and INIBD, except for one case of INIBD. These findings suggest that autophagy–lysosome pathway is not involved in the formation/degradation of NIIs.

Ubiquilin immunoreactivity in cytoplasmic and nuclear inclusions in synucleinopathies, polyglutamine diseases and intranuclear inclusion body disease

Ubiquilin immunoreactivity in cytoplasmic and nuclear inclusions in synucleinopathies, polyglutamine diseases and intranuclear inclusion body disease

FUS immunoreactivity of neuronal and glial intranuclear inclusions in intranuclear inclusion body disease

Recent studies have shown that fused-in-sarcoma (FUS) protein is a component of 'neuronal' intranuclear inclusion bodies (INIBs) in the brains of patients with intranuclear inclusion body disease (INIBD). However, the extent and frequency of FUS-immunoreactive structures in INIBD are uncertain. We immunohistochemically examined the brain, spinal cord and peripheral ganglia from five patients with INIBD and five control subjects, using anti-FUS antibodies. In controls, the nuclei of both neurones and glial cells were intensely immunolabelled with anti-FUS and neuronal cytoplasm was weakly positive for FUS. In INIBD, neuronal and glial INIBs in the brain and spinal cord were positive for FUS. FUS-positive INIBs were also found in the peripheral ganglia. The proportion of FUS-positive neuronal INIBs relative to the total number of inclusion-bearing neurones ranged from 55.6% to 83.3% (average 73.2%) and that of FUS-positive glial INIBs ranged from 45.9% to 85.7% (average 62.7%). The nucleus and cytoplasm of inclusion-bearing neurones and glial cells showed no FUS immunoreactivity. These findings suggest that FUS is incorporated into INIBs in both neurones and glial cells and that loss of normal FUS immunoreactivity may result from reduced protein expression and/or sequestration within inclusions.

Ubiquitin‐related proteins in neuronal and glial intranuclear inclusions in intranuclear inclusion body disease

Recent studies have shown that eosinophilic intranuclear inclusions (INI) in the brain of patients with intranuclear inclusion body disease (INIBD) are immunopositive for ubiquitin and ubiquitin-related proteins (URP). However, the extent and frequency of URP-immunoreactive inclusions in INIBD are uncertain. We immunohistochemically examined the brain, spinal cord and dorsal root ganglia from five patients with INIBD, using a virtual slide system with sequential staining of the same sections with hematoxylin and eosin and by immunolabeling with antibodies against ubiquitin and URP (NEDD8, NUB1, SUMO-1 and SUMO-2). Intranuclear inclusions were widely distributed in neurons and glial cells in all the cases. Sequential staining revealed that 100% of INI in neurons and glial cells were positive for ubiquitin. Moreover, the majority or a significant proportion of INI were positive for NEDD8, NUB1, SUMO-1 and SUMO-2. However, the proportions of NEDD8-, NUB1- and SUMO-1-positive inclusions were significantly higher in neurons than in glial cells (P < 0.05). These findings suggest that proteins related to ubiquitination and proteasomal degradation are involved in the formation of INI in INIBD.

Optineurin immunoreactivity in neuronal nuclear inclusions of polyglutamine diseases (Huntington’s, DRPLA, SCA2, SCA3) and intranuclear inclusion body disease

Optineurin (OPTN) is a ubiquitous cytoplasmic protein with various functions including membrane trafficking and signal transduction [9]. OPTN mutations are associated with adult-onset glaucoma and familial and sporadic amyotrophic lateral sclerosis (ALS) [4]. OPTN immunoreactivity has been reported in a variety of ubiquitinated inclusions including ALS-associated neuronal cytoplasmic inclusions, neurofibrillary tangles in Alzheimer’s disease, Pick bodies in Pick disease, Lewy bodies in Parkinson’s disease and glial cytoplasmic inclusions in multiple system atrophy [3, 6]. With respect to polyglutamine diseases, neuronal nuclear inclusions (NNIs) in Huntington’s disease (HD) and spinocerebellar ataxia type 3 (SCA3) are reported to be immunonegative for OPTN [2]. However, Schwab et al. [7] have contended that NNIs in HD are immunopositive for OPTN. We report that OPTN immunoreactivity is present in NNIs in various polyglutamine diseases and intranuclear inclusion body disease (INIBD). A total of 30 post-mortem cases were utilized in the present study; these included cases of HD (n = 3), dentatorubral-pallidoluysian atrophy (DRPLA; n = 5), SCA2 (n = 1), SCA3 (n = 5), SCA6 (n = 2), SCA17 (n = 1), spinal and bulbar muscular atrophy (SBMA; n = 3), INIBD (n = 5) and normal control subjects (n = 5). The diagnoses of polyglutamine diseases were confirmed genetically and histopathologically. Immunohistochemical analysis was carried out using formalin-fixed, paraffinembedded sections from the basal ganglia in HD, SCA2 and SCA17, the pons in DRPLA and SCA3, the cerebellum in SCA6, the spinal cord in SBMA, the frontal lobe in INIBD, and the cortical and subcortical regions in control subjects. Anti-ubiquitin (1B3; MBL, Nagoya, Japan), antipolyglutamine (1C2; Chemicon, Temecula, CA, USA) and anti-human OPTN C terminus (#100000; Cayman CHEMICAL, Ann Arbor, MI, USA) [2, 7, 8] were used as primary antibodies. In controls, anti-OPTN antibody weakly immunolabeled the neuronal cytoplasm in a diffuse granular pattern, and neuronal nuclei were negative for OPTN (Fig. 1a). OPTN-immunoreactive NNIs were found in all the cases of HD, DRPLA, SCA2 and SCA3 (Fig. 1b–e). Intranuclear inclusions in neurons, but not in glial cells, in INIBD were also immunopositive for OPTN (Fig. 1f). Double immunofluorescence analyses revealed that OPTN immunoreactivity was found in 69% of NNIs in HD, 46% in DRPLA, 17% in SCA2, 55% in SCA3 and 50% in INIBD (Fig. 2). Although ubiquitinated NNIs were seen in SCA17 and SBMA, these inclusions were F. Mori (&) K. Tanji K. Wakabayashi Department of Neuropathology, Institute of Brain Science, Hirosaki University Graduate School of Medicine, 5 Zaifu-cho, Hirosaki 036-8562, Japan e-mail: neuropal@cc.hirosaki-u.ac.jp

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.

FUS-immunoreactive intranuclear inclusions in neurodegenerative disease.

Neuronal intranuclear inclusions (NIIs) are a histopathological hallmark of several neurodegenerative disorders. However, the role played by NIIs in neurodegenerative pathogenesis remains enigmatic. Defining their molecular composition represents an important step in understanding the pathophysiology of these disorders. Recently, a nuclear protein, "fused-in-sarcoma" (FUS) was identified as the pathological protein in two forms of frontotemporal lobar degeneration (FTLD-IF, formerly known as neuronal intermediate filament inclusion disease, and FTLD-UPS, formerly known as atypical FTLD-U), both of which are characterized by the presence of NII. The objective of the present study was to determine the range of neurodegenerative disorders characterized by FUS-positive NIIs. Immunostaining for FUS revealed intense reactivity of NIIs in FTLD-IF and FTLD-UPS as well as in Huntington's disease, spinocerebellar ataxias 1 and 3, and neuronal intranuclear inclusion body disease. In contrast, there was no FUS staining of NIIs in inherited forms of FTLD-TDP caused by GRN and VCP mutations, fragile-X-associated tremor ataxia syndrome, or oculopharyngeal muscular dystrophy. In a cell culture model of Huntington's disease, NIIs were intensely FUS-positive. NII-bearing cells displayed loss of the normal diffuse nuclear pattern of FUS staining. This suggests that sequestration of nuclear FUS by NIIs may interfere with its normal nuclear localization.

Inclusion-positive cell types in adult-onset intranuclear inclusion body disease: implications for clinical diagnosis

The distribution of inclusions in adult-onset type intranuclear inclusion body disease (INIBD) has not been fully described. We analyzed the clinical and pathological changes of three autopsy cases of adult type INIBD and provide a detailed description of the distribution of inclusions in nervous system and visceral organs. Although patients showed cognitive decline and autonomic dysfunction, there were no specific symptoms related to general organs. The neuropathological changes responsible for cognitive decline and autonomic dysfunction were considered to be white matter changes in the cerebral hemispheres and inclusions in the autonomic nervous system, e.g., in the sympathetic ganglia and myenteric plexus. Alterations of spongiosis with both myelin and axon loss in the cerebral white matter seemed to be related to dysfunction of astrocytes with intranuclear inclusions. In visceral organs, the inclusions were much more widely distributed than previously appreciated and included renal mesangial cells, adrenal sustentacular cells, fibrocytes, Kupffer cells, pancreatic centroacinar and ductal epithelial cells. Since skeletal muscle cells, Schwann cells and smooth muscle cells were also inclusion positive, we propose that biopsy of muscle, peripheral nerve or rectum may prove useful for the clinical diagnosis of INIBD.