[Neuropathology of Disorders Leading to Dementia].

Dementia is characterized by acquired cognitive dysfunction caused by various neurological disorders. Many neurological conditions can cause dementia, including neurodegenerative diseases, vascular disorders, infections, inflammation, demyelination, intoxication, metabolic disorders, tumors, and head trauma. Despite recent developments in biomarkers and imaging techniques, neuropathological examination is necessary for the final diagnosis. Moreover, approximately 11% of the patients with dementia have dual or triple pathological conditions. The coexistence of neurological diseases makes it difficult for neurologists to diagnose patients accurately. Degenerative diseases are characterized by neuronal loss with gliosis in distinct parts of the brain, the presence of neuronal or glial inclusions, and abnormal protein accumulation. Senile plaques and neurofibrillary tangles are neuropathological hallmarks of Alzheimer's disease. These findings are characterized by the presence of amyloid ß protein (Aß) and phosphorylated tau protein, respectively. Although vascular dementia is common, it may be difficult to identify the relationship between vascular lesions and cognitive impairment. The incidence of sporadic Aß-type cerebral amyloid angiopathy (CAA) tends to increase with age and causes dementia due to vascular dysfunction and leukoencephalopathy. Furthermore, patients with CAA can develop inflammation. Clinical neurologists should possess a neuropathological perspective for the appropriate diagnosis and management of patients with dementia.

Nationwide Laboratory Surveillance of Progressive Multifocal Leukoencephalopathy in Japan: Fiscal Years 2011-2020.

Progressive multifocal leukoencephalopathy (PML) is a devastating demyelinating disease caused by JC virus (JCV), predominantly affecting patients with impaired cellular immunity. PML is a non-reportable disease with a few exceptions, making national surveillance difficult. In Japan, polymerase chain reaction (PCR) testing for JCV in the cerebrospinal fluid (CSF) is performed at the National Institute of Infectious Diseases to support PML diagnosis. To clarify the overall profile of PML in Japan, patient data provided at the time of CSF-JCV testing over 10 years (FY2011-2020) were analyzed. PCR testing for 1537 new suspected PML cases was conducted, and 288 (18.7%) patients tested positive for CSF-JCV. An analysis of the clinical information on all individuals tested revealed characteristics of PML cases, including the geographic distribution, age and sex patterns, and CSF-JCV-positivity rates among the study subjects for each type of underlying condition. During the last five years of the study period, a surveillance system utilizing ultrasensitive PCR testing and widespread clinical attention to PML led to the detection of CSF-JCV in the earlier stages of the disease. The results of this study will provide valuable information not only for PML diagnosis, but also for the treatment of PML-predisposing conditions.

Vacuoles related to tissue neuron-astrocyte ratio and infiltration of macrophages/monocytes contribute to hyperintense brain signals on diffusion-weighted magnetic resonance imaging in sporadic Creutzfeldt-Jakob disease.

BACKGROUND: Radiological features in patients with sporadic Creutzfeldt-Jakob disease (sCJD) are hyperintensity of the cerebral cortex and the basal ganglia displayed by diffusion-weighted magnetic resonance imaging (DW-MRI). We performed a quantitative study on neuropathological and radiological findings. METHODS: Patient 1 received a definite diagnosis of MM1-type sCJD, while patient 2 received a definite diagnosis of MM1 + 2-type sCJD. Two DW-MRI scans were performed on each patient. DW-MRI was either taken the day before or on the day of the patient's death, and several hyperintense or isointense areas were marked as a region of interest (ROI). Mean signal intensity of the ROI was measured. Pathological quantitative assessments of the vacuoles, astrocytosis, infiltration of monocytes/macrophages, and proliferation of microglia was performed. Vacuole load (% area vacuole), glial fibrillary acidic protein (GFAP), CD68, and Iba-1 load were calculated. We defined spongiform change index (SCI) to indicate vacuoles related to a tissue neuron-astrocyte ratio. We assessed the correlation of intensity of the last DW-MRI and the pathological findings as well as association of changes of the signal intensity on the sequential images and the pathological findings. RESULT: We observed a strong positive correlation between SCI and DW-MRI intensity. In the analysis using serial DW-MRI and pathological findings, we found that CD68 load was significantly larger in areas where signal intensity decreased, as compared to those areas where hyperintensity remained unchanged. CONCLUSION: DW-MRI intensity in sCJD is associated with the ratio of neuron to astrocyte in the vacuoles and the infiltration of macrophages and/or monocytes.

Cerebrospinal Fluid Biomarkers and Amyloid-ß Elimination from the Brain in Cerebral Amyloid Angiopathy-Related Inflammation.

BACKGROUND: Cerebrospinal fluid (CSF) biomarkers in patients with cerebral amyloid angiopathy-related inflammation (CAA-ri) have demonstrated inconsistent results. OBJECTIVE: We investigated the relationship between CSF amyloid-ß protein (Aß) and vascular pathological findings to elucidate the mechanisms of Aß elimination from the brain in CAA-ri. METHODS: We examined Aß40 and Aß42 levels in CSF samples in 15 patients with CAA-ri and 15 patients with Alzheimer's disease and cerebral amyloid angiopathy (AD-CAA) using ELISA as a cross-sectional study. Furthermore, we pathologically examined Aß40 and Aß42 depositions on the leptomeningeal blood vessels (arteries, arterioles, and veins) using brain biopsy samples from six patients with acute CAA-ri and brain tissues of two autopsied patients with CAA-ri. RESULTS: The median Aß40 and Aß42 levels in the CSF showed no significant difference between pre-treatment CAA-ri (Aß40, 6837 pg/ml; Aß42, 324 pg/ml) and AD-CAA (Aß40, 7669 pg/ml, p = 0.345; Aß42, 355 pg/ml, p = 0.760). Aß40 and Aß42 levels in patients with post-treatment CAA-ri (Aß40, 1770 pg/ml, p = 0.056; Aß42, 167 pg/ml, p = 0.006) were lower than those in patients with pre-treatment CAA-ri. Regarding Aß40 and Aß42 positive arteries, acute CAA-ri cases showed a higher frequency of partially Aß-deposited blood vessels than postmortem CAA-ri cases (Aß40, 20.8% versus 3.9%, p = 0.0714; Aß42, 27.4% versus 2.0%, p = 0.0714, respectively). CONCLUSION: Lower levels of CSF Aß40 and Aß42 could be biomarkers for the cessation of inflammation in CAA-ri reflecting the recovery of the intramural periarterial drainage pathway and vascular function.

CD59 Expression in Skeletal Muscles and Its Role in Myasthenia Gravis.

BACKGROUND AND OBJECTIVES: Complement regulatory proteins at the neuromuscular junction (NMJ) could offer protection against complement-mediated damage in myasthenia gravis (MG). However, there is limited information on their expression at the human NMJ. Thus, this study aimed at investigating the expression of the cluster of differentiation 59 (CD59) at the NMJ of human muscle specimens and demonstrating the overexpression of CD59 mRNA and protein in the muscles of patients with MG. METHODS: In this observational study, muscle specimens from 16 patients with MG (9 and 7 patients with and without thymoma, respectively) and 6 nonmyopathy control patients were examined. Immunohistochemical stains, Western blot analysis, and quantitative real-time reverse transcription PCR were used to evaluate the CD59 expression. RESULTS: A strong localized expression of CD59 was observed at the NMJ in both patients with and without MG. Moreover, the CD59/glyceraldehyde-3-phosphate dehydrogenase protein ratio in patients with MG was significantly higher than that in the nonmyopathy controls (MG; n = 16, median 0.16, interquartile range (IQR) 0.08-0.26 and nonmyopathy controls; n = 6, median 0.03, IQR 0.02-0.11, p = 0.01). The proportion of CD59 mRNA expression relative to AChR mRNA expression (ΔCtCD59/AChR) was associated with the quantitative MG score, MG activities of daily living score, and MG of Foundation of America Clinical Classification (r = 0.663, p = 0.01; r = 0.638, p = 0.014; and r = 0.715, p = 0.003, respectively). DISCUSSION: CD59, which acts as a complement regulator, may protect the NMJ from complement attack. Our findings could provide a basis for further research that investigates the underlying pathogenesis in MG and the immunomodulating interactions of the muscle cells.

Polyphenols for the Prevention and Treatment of Cognitive Impairment.

Epidemiological studies have suggested that diets rich in polyphenols/phenolic compounds are associated with reduced risk of cognitive impairment and Alzheimer's disease (AD). Experimental studies have indicated that these compounds have specific effects on AD pathogenesis as well as anti-oxidant and anti-inflammatory effects. For clinical use, several compounds have been investigated by clinical trials to establish their efficacy for prevention and treatment of AD or cognitive impairment.

Extracellular Vesicles Contribute to the Metabolism of Transthyretin Amyloid in Hereditary Transthyretin Amyloidosis.

Hereditary (variant) transthyretin amyloidosis (ATTRv amyloidosis), which is caused by variants in the transthyretin (TTR) gene, leads to TTR amyloid deposits in multiple organs and various symptoms such as limb ataxia, muscle weakness, and cardiac failure. Interaction between amyloid proteins and extracellular vesicles (EVs), which are secreted by various cells, is known to promote the clearance of the proteins, but it is unclear whether EVs are involved in the formation and deposition of TTR amyloid in ATTRv amyloidosis. To clarify the relationship between ATTRv amyloidosis and EVs, serum-derived EVs were analyzed. In this study, we showed that cell-derived EVs are involved in the formation of TTR amyloid deposits on the membrane of small EVs, as well as the deposition of TTR amyloid in cells. Human serum-derived small EVs also altered the degree of aggregation and deposition of TTR. Furthermore, the amount of TTR aggregates in serum-derived small EVs in patients with ATTRv amyloidosis was lower than that in healthy controls. These results indicate that EVs contribute to the metabolism of TTR amyloid, and suggest that TTR in serum-derived small EVs is a potential target for future ATTRv amyloidosis diagnosis and therapy.

Transmission of Cerebral ß-Amyloidosis Among Individuals.

Deposition of amyloid ß protein (Aß) in the brain (cerebral ß-amyloidosis) is a hallmark of Alzheimer's disease (AD). So far, there have been increasing number of experimental studies using AD mouse model that cerebral ß-amyloidosis could be transmitted among individuals as prion-like mechanism. Furthermore, several pathological studies using autopsied patients with iatrogenic Creutzfeldt-Jakob disease (CJD) showed that cerebral ß-amyloidosis in addition to the CJD pathology could be transmitted among humans via medical procedures, such as human growth hormone derived from cadaver injection and cadaveric dura mater graft. In addition, although cerebral amyloid angiopathy (CAA), which is Aß deposition in the cerebral vessels, related cerebral hemorrhage rarely develops in young people, several patients with CAA-related cerebral hemorrhage under the age of 55 with histories of neurosurgeries with and without dura mater graft in early childhood have been reported. These patients might show that Aß pathology is often recognized as Aß-CAA rather than parenchymal Aß deposition in the transmission of cerebral ß-amyloidosis in humans, and we proposed an emerging concept, "acquired CAA". Considering that there have been several patients with acquired CAA with an incubation period from neurosurgery and the onset of CAA related cerebral hemorrhage of longer than 40 years, the number of cases is likely to increase in the future, and detailed epidemiological investigation is required. It is necessary to continue to elucidate the pathomechanisms of acquired CAA and urgently establish a method for preventing the transmission of cerebral ß-amyloidosis among individuals.

Deterioration after Liver Transplantation and Transthyretin Stabilizer Administration in a Patient with ATTRv Amyloidosis with a Leu58Arg (p.Leu78Arg) TTR Variant.

We herein report a 44-year-old Japanese man with hereditary transthyretin amyloidosis (ATTRv amyloidosis) harboring the variant Leu58Arg (p.Leu78Arg) in TTR in whom we conducted an observational study with liver transplantation (LT) and transthyretin (TTR) stabilizers (tafamidis and diflunisal) for 9 years. This patient showed gradual deterioration of sensory, motor, and autonomic neuropathy symptoms after LT. Furthermore, cardiac amyloidosis gradually developed. Although the present case showed deterioration of the symptoms after disease-modifying treatments, LT might be suitable in patients with the same variant if they are young and in good condition due to a long survival after LT.

Familial idiopathic basal ganglia calcification with a heterozygous missense variant (c.902C>T/p.P307L) in SLC20A2 showing widespread cerebrovascular lesions.

We describe a postmortem case of familial idiopathic basal ganglia calcification (FIBGC) in a 72-year-old Japanese man. The patient showed progressive cognitive impairment with a seven-year clinical course and calcification of the basal ganglia, thalami, and cerebellar dentate nuclei. A novel heterozygous missense variant in SLC20A2 (c.920C>T/p.P307L), a type III sodium-dependent phosphate transporter (PiT-2), was subsequently identified, in addition to typical neuropathological findings of FIBGC, such as capillary calcification of the occipital gray matter, confluent calcification of the basal ganglia and cerebellar white matter, widespread occurrence of vasculopathic changes, cerebrovascular lesions, and vascular smooth muscle cell depletion. Immunohistochemistry for PiT-2 protein revealed no apparent staining in endothelial cells in the basal ganglia and insular cortex; however, the immunoreactivity in endothelial cells of the cerebellum was preserved. Moreover, Western blot analysis identified preserved PiT-2 immunoreactivity signals in the frontal cortex and cerebellum. The variant identified in the present patient could be associated with development of FIBGC and is known to be located at the large intracytoplasmic part of the PiT-2 protein, which has potential phosphorylation sites with importance in the regulation of inorganic phosphate transport activity. The present case is an important example to prove that FIGBC could stem from a missense variant in the large intracytoplasmic loop of the PiT-2 protein. Abnormal clearance of inorganic phosphate in the brain could be related to the development of vascular smooth muscle damage, the formation of cerebrovascular lesions, and subsequent brain calcification in patients with FIBGC with SLC20A2 variants.

Hypertrophic Pachymeningitis with Characteristics of Both IgG4-related Disorders and Granulomatosis with Polyangiitis.

We herein report a 73-year-old man with isolated hypertrophic pachymeningitis (HP) showing serological and pathological characteristics of both IgG4-related disorders and granulomatosis with polyangiitis. The patient presented with chronic onset headaches and ophthalmalgia. Brain magnetic resonance imaging (MRI) revealed a hypertrophic enhanced dura mater. Serum IgG4 and myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) levels were elevated. A dura mater biopsy showed infiltration of numerous IgG4-positive plasma cells and granulomatous inflammation without apparent vasculitic lesions, storiform fibrosis, or obstructive phlebitis. Corticosteroid treatments improved his clinical symptoms and MRI findings. There have been reports of MPO-ANCA-positive IgG4-related HP presenting as granulomatous inflammation in the dura mater.

Lewy pathology of the submandibular gland in Lewy body disease: A report of autopsy cases.

Accumulation of phosphorylated α-synuclein in the central and peripheral nervous systems is a histological hallmark of Lewy body disease (LBD), including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and LB-related pure autonomic failure. The submandibular gland is employed as a biopsy site for detecting Lewy pathology; however, the incidence of Lewy pathology in this region in autopsy-proven LBD cases at all stages from an aged Japanese cohort remains unclear. To validate the utility of Lewy pathology of the submandibular gland as a diagnostic biomarker for LBD, we investigated the submandibular gland Lewy pathology in autopsied patients. To determine the specificity, we prospectively evaluated the submandibular gland in 64 consecutive autopsied patients. To determine the sensitivity, we retrospectively assessed the submandibular gland in 168 consecutive autopsied patients who had prodromal or clinical LBD. In the prospective study, Lewy pathology was found in 21 of 64 patients, and nine of those 21 patients had the submandibular gland Lewy pathology. No Lewy pathology was found in 43 patients without CNS Lewy pathology, giving a specificity of 100%. In the retrospective study, Lewy pathology of the submandibular gland was detected in 126 of 168 patients. The sensitivity was 89.1% in PD and 75.4% in DLB. The sensitivity increased with disease progression. These findings support the utility of the submandibular gland biopsy for the pathological diagnosis of LBD.

Late-onset acute disseminated encephalomyelitis followed by optic neuritis without anti-myelin oligodendrocyte glycoprotein antibodies: a biopsied case report.

BACKGROUND: Acute disseminated encephalomyelitis (ADEM) followed by optic neuritis (ADEM-ON) is characterized by the following features: early onset, monophasic or multiphasic ADEM followed by one or more episodes of ON, and the presence of serum anti-myelin oligodendrocyte glycoprotein (MOG) antibodies. CASE REPORT: We report a case of ADEM-ON without anti-MOG antibodies in a 78-year-old woman. The patient developed acute-onset neurological findings and was diagnosed with ADEM. She was treated with intravenous methylprednisolone (IVMP), and oral corticosteroids. Her clinical symptoms and MRI findings subsequently improved. Left optic neuritis emerged 6 months later, and we made a diagnosis of ADEM-ON. A brain biopsy performed during the acute phase of ADEM showed perivascular infiltration of macrophages with demyelination. CONCLUSION: The majority of the reported ADEM-ON cases are pediatric cases with serum anti-MOG antibodies, but our patient was the elderly, without anti-MOG antibodies. Moreover, the pathological features of our case were similar to those observed in patients with typical ADEM and in patients with anti-MOG antibody-positive ADEM. Although ADEM-ON is related to the presence of anti-MOG antibodies, factors other than anti-MOG antibodies could contribute to the development of ADEM-ON.

[Cerebral Amyloid Angiopathy-Related Inflammation/Vasculitis].

Cerebral amyloid angiopathy (CAA) is a disorder characterized by the deposition of amyloid in the leptomeningeal and cortical blood vessels. Sporadic amyloid ß (Aß)-type CAA is the most common form of CAA. Although CAA is a well-known cause for recurrent cerebral lobar hemorrhage, inflammation, and vasculitis, CAA-related inflammation/vasculitis (CAA-ri/vasculitis) induced by Aß deposition on vessel walls is emerging as a treatable condition. The estimated total number of cases of and prevalence of CAA-ri/vasculitis in Japan were 170 and 0.13 per 100 000 population, respectively. Patients with CAA-ri/vasculitis show acute or subacute-onset of cognitive impairment, behavioral changes, and headache. Brain magnetic resonance imaging, showing asymmetrical white matter abnormalities and occasional meningeal enhancement, is a useful tool for the diagnosis of CAA-ri/vasculitis. Moreover, elevation of anti-Aß antibodies and inflammatory markers in the cerebrospinal fluid can help in clinical diagnosis. Although several clinical diagnostic criteria have been proposed, neuropathological examination of a brain biopsy remains the gold standard for detecting severe Aß deposition and vasculopathic changes with lymphocytic infiltrations and/or granulomatous vasculitis. No validated treatment regimen has been established to date. Nearly 80% patients with CAA-ri/vasculitis improved after immunosuppressant therapy with corticosteroid and/or cyclophosphamide. Early treatment is essential to prevent irreversible sequelae in the brain.

Myricetin prevents high molecular weight Aß1-42 oligomer-induced neurotoxicity through antioxidant effects in cell membranes and mitochondria.

Excessive accumulation of amyloid ß-protein (Aß) is one of the primary mechanisms that leads to neuronal death with phosphorylated tau in the pathogenesis of Alzheimer's disease (AD). Protofibrils, one of the high-molecular-weight Aß oligomers (HMW-Aßo), are implicated to be important targets of disease modifying therapy of AD. We previously reported that phenolic compounds such as myricetin inhibit Aß1-40, Aß1-42, and α-synuclein aggregations, including their oligomerizations, which may exert protective effects against AD and Parkinson's disease. The purpose of this study was to clarify the detailed mechanism of the protective effect of myricetin against the neurotoxicity of HMW-Aßo in SH-SY5Y cells. To assess the effect of myricetin on HMW-Aßo-induced oxidative stress, we systematically examined the level of membrane oxidative damage by measuring cell membrane lipid peroxidation, membrane fluidity, and cell membrane potential, and the mitochondrial oxidative damage was evaluated by mitochondrial permeability transition (MPT), mitochondrial reactive oxygen species (ROS), and manganese-superoxide dismutase (Mn-SOD), and adenosine triphosphate (ATP) assay in SH-SY5Y cells. Myricetin has been found to increased cell viability by suppression of HMW-Aßo-induced membrane disruption in SH-SY5Y cells, as shown in reducing membrane phospholipid peroxidation and increasing membrane fluidity and membrane resistance. Myricetin has also been found to suppress HMW-Aßo-induced mitochondria dysfunction, as demonstrated in decreasing MPT, Mn-SOD, and ATP generation, raising mitochondrial membrane potential, and increasing mitochondrial-ROS generation. These results suggest that myricetin preventing HMW-Aßo-induced neurotoxicity through multiple antioxidant functions may be developed as a disease-modifying agent against AD.

Rosmarinic acid suppresses tau phosphorylation and cognitive decline by downregulating the JNK signaling pathway.

Rosmarinic acid (RA), a polyphenol found in Lamiaceae herbs, is a candidate of preventive ingredients against Alzheimer's disease (AD) as it potently suppresses the aggregation of amyloid ß (Aß); however, the effect of RA on tau phosphorylation and cognitive dysfunction remains unclear. The present study revealed that RA intake inhibited the pathological hallmarks of AD, including Aß and phosphorylated tau accumulation, and improved cognitive function in the 3 × Tg-AD mouse model. Additionally, RA intake suppressed hippocampal inflammation and led to the downregulation of the JNK signaling pathway that induces tau phosphorylation. Feeding with RA exerted an anti-inflammatory effect not only in the central nervous system but also in the periphery. Downregulation of the JNK signaling pathway in hippocampus may be a potential mechanism underlying the inhibition of progression of pathology and cognitive deficit by RA feeding.

MM2-type sporadic Creutzfeldt-Jakob disease: new diagnostic criteria for MM2-cortical type.

OBJECTIVE: To clinically diagnose MM2-cortical (MM2C) and MM2-thalamic (MM2T)-type sporadic Creutzfeldt-Jakob disease (sCJD) at early stage with high sensitivity and specificity. METHODS: We reviewed the results of Creutzfeldt-Jakob disease Surveillance Study in Japan between April 1999 and September 2019, which included 254 patients with pathologically confirmed prion diseases, including 9 with MM2C-type sCJD (MM2C-sCJD) and 10 with MM2T-type sCJD (MM2T-sCJD), and 607 with non-prion diseases. RESULTS: According to the conventional criteria of sCJD, 4 of 9 patients with MM2C- and 7 of 10 patients with MM2T-sCJD could not be diagnosed with probable sCJD until their death. Compared with other types of sCJD, patients with MM2C-sCJD showed slower progression of the disease and cortical distribution of hyperintensity lesions on diffusion-weighted images of brain MRI. Patients with MM2T-sCJD also showed relatively slow progression and negative results for most of currently established investigations for diagnosis of sCJD. To clinically diagnose MM2C-sCJD, we propose the new criteria; diagnostic sensitivity and specificity to distinguish 'probable' MM2C-sCJD from other subtypes of sCJD, genetic or acquired prion diseases and non-prion disease controls were 77.8% and 98.5%, respectively. As for MM2T-sCJD, clinical and laboratory features are not characterised enough to develop its diagnostic criteria. CONCLUSIONS: MM2C-sCJD can be diagnosed at earlier stage using the new criteria with high sensitivity and specificity, although it is still difficult to diagnose MM2T-sCJD clinically.