水谷 泰彰

BACKGROUND: Weight loss is a substantial non-motor feature of Parkinson's disease (PD) associated with worse clinical outcomes, but the underlying mechanisms remain poorly understood. Thus, we investigated the mechanisms of PD-related weight loss by examining the correlation between body composition and various plasma metabolites. METHODS: We enrolled 91 patients with PD and 47 healthy controls between July 2021 and October 2023. Body composition was evaluated using bioelectrical impedance analysis. Plasma metabolite profiling was conducted via mass spectrometry, including short-chain and medium-chain fatty acids, Krebs cycle intermediates, ketone bodies and phospholipids. Subsequently, alterations in body composition in PD and their association with plasma metabolites were assessed. RESULTS: Patients with PD had lower body weight (p=0.003), body mass index (BMI; p=0.001) and body fat mass (p<0.001) compared with controls. Metabolomic analyses revealed that, in patients with PD, glycolysis and Krebs cycle markers (lactic acid and succinic acid) were reduced, while ketone bodies (acetoacetic acid and 3-hydroxybutyric acid), amino acid catabolism-related markers (2-hydroxybutyric acid and 2-oxobutyric acid) and acetic acid were elevated. Notably, in patients with PD, acetoacetic acid and 3-hydroxybutyric acid negatively correlated with BMI. Phosphatidylcholine (40:2) was also elevated in PD and showed higher levels in individuals at more advanced Hoehn and Yahr stages. CONCLUSIONS: PD-related fat loss was accompanied by a pattern of lower glycolytic activity and higher levels of lipid and amino acid metabolism-related metabolites, consistent with a potential shift in energy utilisation. These findings highlight metabolic pathways as potential targets for interventions to mitigate weight loss in PD.

Background/Objectives: Myotonic dystrophy type 1 (DM1) is a multisystem disorder that affects the central nervous system. Despite previous studies, blood-based biomarkers have not been sufficiently characterized. This study investigated plasma neurofilament light chain (NfL), phosphorylated tau (p-tau181), amyloid-β (Aβ42/40), and glial fibrillary acidic protein (GFAP) in a Japanese cohort with DM1 to assess their potential as biomarkers. Methods: Forty patients with genetically confirmed DM1 were enrolled in this study. Plasma NfL, p-tau181, Aβ42/40, and GFAP were quantified using single-molecule array technology. Clinical and genetic variables, including age, CTG repeat size, Mini-Mental State Examination (MMSE) score, modified Rankin Scale (mRS) score, and creatine kinase levels, were analyzed for correlations. Results: NfL and p-tau181 were significantly elevated in patients with DM1 compared with controls, with 95% exceeding the p-tau181 cut-off. NfL was moderately correlated with age, age at onset, and mRS, and no significant associations were observed between p-tau181 and other biomarkers, although a correlation was noted with serum creatine kinase. Conclusions: These findings support that NfL is a marker of disease severity in DM1 and identified plasma p-tau181 as a potential novel biomarker. While the mechanisms underlying the increased p-tau181 levels remain unclear, they may reflect DM1-related pathologies in the brain and possibly in skeletal muscle. Study limitations include a small sample size and lack of age-matched controls, highlighting the need for longitudinal validation. This study demonstrates the utility of NfL and suggests that p-tau181 is an emerging biomarker for DM1, supporting future work toward biomarker-guided monitoring and therapeutic evaluation.

BACKGROUND: Lysosomal dysfunction is recognized as a key pathological feature of Parkinson's disease (PD); however, its peripheral signatures remain unclear. METHODS: This study evaluated the peripheral profiles of lysosomal hydrolases and their regulation by transcription factor EB (TFEB), focusing on α-galactosidase A (GLA) and β-mannosidase in the peripheral blood mononuclear cells (PBMCs) of 63 PD patients and 44 healthy controls. Lysosomal enzyme activities in PBMC homogenates and serum were quantified using a fluorometric enzymatic assay with kinetic analysis. Protein concentrations were measured by ELISA, and TFEB activation status was evaluated by its phosphorylation level using western blotting. RESULTS: GLA activity and protein concentrations were higher in the PBMCs of patients, but not for β-mannosidase. TFEB protein concentrations were also elevated and showed positive correlations with lysosomal enzyme protein concentrations. TFEB phosphorylation status showed that the ratio of non-phosphorylated to total TFEB did not differ between PD and controls. However, within the PD group, this ratio negatively correlated with TFEB concentrations, suggesting a potential uncoupling between TFEB expression and its functional activation status. Furthermore, both serum-to-PBMC ratios of GLA activity and protein concentration were lower in PD and were associated with PBMC counts, indicating impaired enzyme release from PBMC. CONCLUSIONS: Elevated TFEB expression in PBMCs may reflect a compensatory response to PD-related cellular stress. However, this response may be functionally insufficient due to limited TFEB activity, potentially leading to reduced lysosomal enzyme release. Thus, peripheral TFEB-related lysosomal abnormalities may serve as indicators of systemic autophagy-lysosome dysregulation in PD.

OBJECTIVE: Cerebrospinal fluid (CSF) cell-free mitochondrial DNA (cf-mtDNA) is a potential biomarker for Parkinson's disease (PD), but its clinical relevance remains unclear. We investigated associations between CSF cf-mtDNA levels, body composition, nutritional status, and metabolic biomarkers in PD. METHODS: CSF cf-mtDNA levels, defined as the copy numbers of two regions of the mtDNA circular molecule (mt64-ND1 and mt96-ND5), were quantified in 44 PD patients and 43 controls using multiplex digital PCR. The mt96-ND5/mt64-ND1 ratio was calculated to estimate mtDNA deletion burden. Associations with clinical features, body composition, serum nutritional markers, and plasma energy metabolism-related organic acids were examined. Generalized linear models (GLMs) were performed to adjust for confounders. RESULTS: CSF mt64-ND1 and mt96-ND5 levels were lower in PD patients than controls (p = 0.002, p = 0.001), while the mt96-ND5/mt64-ND1 ratio showed no group difference. GLM analysis identified body composition indices and serum albumin as key determinants of cf-mtDNA levels. Subgroup analysis showed lower cf-mtDNA levels in PD patients with preserved body composition and nutritional status. The mt96-ND5/mt64-ND1 ratio displayed a biphasic association with body composition and an inverse correlation with plasma 2-ketoglutaric acid, suggesting a link to energy metabolism. INTERPRETATION: CSF cf-mtDNA levels are reduced in PD and influenced by body composition and nutritional status, supporting their role as a metabolic biomarker. While the cf-mtDNA deletion ratio remained unchanged, its association with body composition suggests a complex interplay between mitochondrial integrity and metabolism. These findings highlight the relevance of cf-mtDNA in PD pathophysiology and the need for further study.

INTRODUCTION: Progressive supranuclear palsy (PSP) involves midbrain structures, including the red nucleus (RN), an iron-rich region that appears as a high-contrast area on quantitative susceptibility mapping (QSM). RN may serve as a promising biomarker for differentiating parkinsonism. However, RN deformation in PSP remains elusive. This study aimed to evaluate RN deformation in PSP using coronal QSM images and compare them with those of Parkinson's disease (PD) and healthy controls (HC). METHODS: We evaluated the QSM images of 22 patients with PSP, 37 patients with PD, and 43 HC. We developed a grading system to assess RN deformation on coronal QSM images and classified them into three grades. The midbrain and RN volumes were extracted using distinct approaches, and their relationship with grading was investigated. For validation, coronal QSM images of 16 PSP patients from a different institution were assessed. RESULTS: In PSP, 59 % of the patients displayed a flattened RN of grade 3, which we termed a Rice-Grain Appearance. The volume reductions in midbrain and RN were associated with deformation. Differentiation based on the presence of this appearance yielded a specificity of 1.000 (CI: 1.000-1.000) and sensitivity of 0.591 (0.385-0.796) for distinguishing PSP from others. Secondary dataset also showed that 56 % of patients with PSP were classified as grade 3. CONCLUSION: In coronal QSM images, the flattened RN shape appears to be specific to PSP compared to PD and HC and may serve as a marker to help differentiate PSP in future clinical settings.

OBJECTIVES: Sudden death in multiple system atrophy (MSA) is caused by decreased serotonergic innervation, but there is no routine test method for this decrease. In addition to dopamine transporters, iodine-123-labelled N-(3-fluoropropyl)-2β-carbomethoxy-3β-(4-iodophenyl) nortropane (123I-FP-CIT) binds serotonin transporters (SERTs). We noted a binding potential to quantify the total quantity of 123I-FP-CIT binding to its receptors.Following Mintun's binding-potential concept, this study aimed to evaluate the relationship between the specific binding ratio (SBR) and total SERT tissue amount, but not SERT binding, and to develop an SBR imaging method to measure brain-stem SERT. We sought to establish a binding-potential imaging procedure using SBR images to examine differences in the brain-stem SERT distribution between healthy subjects and MSA patients. METHODS: Single-photon emission computed tomography (SPECT) and T1-weighted magnetic resonance (MR) images were aligned. The MR (T1) images were used to set a reference site for the occipital-lobe SBR in each subject, and measurements were made from the SPECT image at the same position. The pixel values and accumulation ratios compared with the occipital lobe were calculated, and a regional SBR distribution image was created. We identified areas with SERT accumulation above a certain level. RESULTS: The SERT accumulation site was visualised as an SBR value on MR images. The accumulation distribution (SERT distribution) on the SBR images significantly differed between the healthy subjects and patients with MSA. CONCLUSION: SERT accumulation was noted in the brain-stem region, indicating that SBR imaging was useful for viewing and quantifying SERT accumulation.

BACKGROUND: Recent evidence suggests a link between glycoprotein non-metastatic melanoma protein B (GPNMB) and Parkinson's disease (PD) pathogenesis. Although elevated plasma GPNMB levels associated with disease severity have been reported in PD, cerebrospinal fluid (CSF) alterations remain elusive. OBJECTIVE: To explore CSF GPNMB alterations and its clinical significance in PD. METHODS: This study enrolled 118 sporadic PD patients and 40 controls. We examined the potential associations between CSF GPNMB levels and the clinical characteristics or biomarkers of neurodegenerative pathogenesis. RESULTS: PD patients had higher CSF GPNMB levels than controls (p = 0.0159). In the PD group, CSF GPNMB levels correlated with age (age at examination: rs = 0.2511, p = 0.0061; age at onset: rs = 0.2800, p = 0.0021) and the severity of motor and cognitive dysfunction (MDS-UPDRS III score: rs = 0.1998, p = 0.0347; Mini-Mental State Examination score: rs = -0.1922, p = 0.0370). After correcting for multiple comparisons, the correlation with age at onset remained significant. CSF GPNMB levels were also positively correlated with CSF soluble triggering receptor expressed on myeloid cells 2 (sTREM2) levels in both the PD (rs = 0.3582, p < 0.0001) and control (rs = 0.4743, p = 0.0023) groups. Furthermore, multiple regression analysis revealed CSF sTREM2 level as the strongest determinant of CSF GPNMB levels in the PD group (t-value = 3.49, p = 0.0007). CONCLUSIONS: Elevated CSF GPNMB levels, linked with age and microglial activation, may be a valuable marker for understanding the interplay between aging, neuroinflammation, and PD pathology.

The relationship between reduced serum uric acid (UA) levels and Parkinson's disease (PD), particularly purine metabolic pathways, is not fully understood. Our study compared serum and cerebrospinal fluid (CSF) levels of inosine, hypoxanthine, xanthine, and UA in PD patients and healthy controls. We analyzed 132 samples (serum, 45 PD, and 29 age- and sex-matched healthy controls; CSF, 39 PD, and 19 age- and sex-matched healthy controls) using liquid chromatography-tandem mass spectrometry. Results showed significantly lower serum and CSF UA levels in PD patients than in controls (p < 0.0001; effect size r = 0.5007 in serum, p = 0.0046; r = 0.3720 in CSF). Decreased serum hypoxanthine levels were observed (p = 0.0002; r = 0.4338) in PD patients compared to controls with decreased CSF inosine and hypoxanthine levels (p < 0.0001, r = 0.5396: p = 0.0276, r = 0.2893). A general linear model analysis indicated that the reduced UA levels were mainly due to external factors such as sex and weight in serum and age and weight in CSF unrelated to the purine metabolic pathway. Our findings highlight that decreased UA levels in PD are influenced by factors beyond purine metabolism, including external factors such as sex, weight, and age, emphasizing the need for further research into the underlying mechanisms and potential therapeutic approaches.

Herpes simplex encephalitis (HSE) is an acute form of encephalitis that can lead to poor neurological outcomes. Although the exact pathogenesis of HSE remains elusive, recent reports suggest a significant role for postinfectious immune-inflammatory processes in the central nervous system (CNS). This study aimed to clarify the association between CNS autoimmune responses and clinical presentation in patients with HSE, focusing on cerebrospinal fluid (CSF) characteristics, particularly the IgG index. We retrospectively analyzed 176 consecutive patients suspected of having aseptic meningitis /encephalitis for chronological changes in CSF findings and clinical presentations. These patients underwent PCR screening for herpesviruses (HV) in their CSF. We identified seven patients positive for herpes simplex virus type 1 (HSV-1), 20 patients positive for varicella-zoster virus, and 17 patients who met the criteria for aseptic meningitis but were PCR-negative for HV. Patients in the HSV-1-positive group exhibited a significant increase in the IgG index at the time of PCR-negative conversion compared with on admission (p = 0.0156), while such a change was not observed in the other two groups. Additionally, all patients in the HSV-1-positive group tested negative for anti-neural autoantibodies in CSF and serum samples collected approximately 3 weeks after onset. This study, therefore, highlights that CSF IgG index elevation occurs even after PCR-confirmed HSV-1 clearance, which might indicate immunopathogenesis that is independent of antibody-mediated mechanisms.

BACKGROUND AND PURPOSE: Multiple system atrophy (MSA) is a neurodegenerative disease with characteristic motor and autonomic symptoms. Impaired brain serotonergic innervation can be associated with various clinical indices of MSA; however, the relationship between clinical symptoms and cerebrospinal fluid (CSF) levels of 5-hydroxyindole acetic acid (5-HIAA), a main serotonin metabolite, has not been fully elucidated. METHODS: To compare CSF 5-HIAA levels between patients with MSA and healthy controls, we included 33 controls and 69 MSA patients with either predominant parkinsonian or cerebellar ataxia subtypes. CSF 5-HIAA levels were measured using high-performance liquid chromatography. Additionally, we investigated correlations between CSF 5-HIAA and various clinical indices in 34 MSA patients. RESULTS: CSF 5-HIAA levels were significantly lower in MSA patients than in controls (p < 0.0001). Probable MSA patients had lower CSF 5-HIAA levels than possible MSA patients (p < 0.001). In MSA patients, CSF 5-HIAA levels were inversely correlated with scores in Parts 1, 2, and 4 of the Unified Multiple System Atrophy Rating Scale, and with systolic and diastolic blood pressure in Part 3. Structural equation modeling revealed significant paths between serotonin and clinical symptoms, and significance was highest for activities of daily living, walking, and body sway. CONCLUSIONS: Serotonin dysfunction, as assessed by CSF 5-HIAA levels, may implicate greater MSA severity.

INTRODUCTION: The King's Parkinson's Disease Pain Scale (KPPS)/King's Parkinson's Disease Pain Questionnaire (KPPQ) was developed as a tool to quantitatively assess pain in patients with Parkinson's disease (PwPD). Here, we conducted a Japanese multicenter validation study to verify the reliability of KPPS/KPPQ in Japanese PwPD. METHODS: PwPD, ≥20 years, with unexplained pain were included; those with a definitive primary cause of pain other than PD were excluded. A total of 151 patients who fulfilled the criteria were analyzed, and test-retest reliability was investigated in 25 individuals. RESULTS: The 151 patients included 101 women (66.9 %); mean age 68.3 ± 9.9 years, mean disease duration 9.2 ± 5.2 years. The most frequent pain type in the KPPS classification was musculoskeletal pain (82.8 %). There was a positive correlation between KPPS total score and the Non-Motor Symptoms Scale (NMSS) total score, NMSS item 27, the Parkinson's disease sleep scale-version 2 (PDSS-2) total score, PDSS-2 item 10, the Parkinson's Disease Questionnaire-8 (PDQ-8) summary index and PDQ-8 item 7. Cronbach's alpha of KPPS was 0.626 (0.562-0.658) and the intraclass correlation coefficient of test-retest reliability was 0.740. Cronbach's alpha of KPPQ was 0.660 (0.617-0.705) and a test-retest reliability of kappa coefficient was 0.593 (0.0-1.0). CONCLUSIONS: KPPS correlated well with other scales for assessing pain. KPPS correlated well with patients' quality of life, non-motor symptoms, and sleep disturbances. The reproducibility of KPPS/KPPQ makes it suitable for continuous evaluation of the same patient. On the other hand, the internal consistency of KPPS/KPPQ is rather low.

Parkinson's disease (PD) involves the disruption of brain energy homeostasis. This encompasses broad-impact factors such as mitochondrial dysfunction, impaired glycolysis, and other metabolic disturbances, like disruptions in the pentose phosphate pathway and purine metabolism. Cortical hubs, which are highly connected regions essential for coordinating multiple brain functions, require significant energy due to their dense synaptic activity and long-range connections. Deficits in ATP production in PD can severely impair these hubs. The energy imbalance also affects subcortical regions, including the massive axonal arbors in the striatum of substantia nigra pars compacta neurons, due to their high metabolic demand. This ATP decline may result in α-synuclein accumulation, autophagy-lysosomal system impairment, neuronal network breakdown and accelerated neurodegeneration. We propose an "ATP Supply-Demand Mismatch Model" to help explain the pathogenesis of PD. This model emphasizes how ATP deficits drive pathological protein aggregation, impaired autophagy, and the degeneration of key brain networks, contributing to both motor and non-motor symptoms.

BACKGROUND: Distinguishing between central nervous system lymphoma (CNSL) and CNS infectious and/or demyelinating diseases, although clinically important, is sometimes difficult even using imaging strategies and conventional cerebrospinal fluid (CSF) analyses. To determine whether detection of genetic mutations enables differentiation between these diseases and the early detection of CNSL, we performed mutational analysis using CSF liquid biopsy technique. METHODS: In this study, we extracted cell-free DNA from the CSF (CSF-cfDNA) of CNSL (N = 10), CNS infectious disease (N = 10), and demyelinating disease (N = 10) patients, and performed quantitative mutational analysis by droplet-digital PCR. Conventional analyses were also performed using peripheral blood and CSF to confirm the characteristics of each disease. RESULTS: Blood hemoglobin and albumin levels were significantly lower in CNSL than CNS infectious and demyelinating diseases, CSF cell counts were significantly higher in infectious diseases than CNSL and demyelinating diseases, and CSF-cfDNA concentrations were significantly higher in infectious diseases than CNSL and demyelinating diseases. Mutation analysis using CSF-cfDNA detected MYD88L265P and CD79Y196 mutations in 60% of CNSLs each, with either mutation detected in 80% of cases. Mutual existence of both mutations was identified in 40% of cases. These mutations were not detected in either infectious or demyelinating diseases, and the sensitivity and specificity of detecting either MYD88/CD79B mutations in CNSL were 80% and 100%, respectively. In the four cases biopsied, the median time from collecting CSF with the detected mutations to definitive diagnosis by conventional methods was 22.5 days (range, 18-93 days). CONCLUSIONS: These results suggest that mutation analysis using CSF-cfDNA might be useful for differentiating CNSL from CNS infectious/demyelinating diseases and for early detection of CNSL, even in cases where brain biopsy is difficult to perform.

OBJECTIVE: Recent studies have revealed an association between Parkinson's disease (PD) and Fabry disease, a lysosomal storage disorder; however, the underlying mechanisms remain to be elucidated. This study aimed to investigate the enzymatic properties of serum alpha-galactosidase A (GLA) and compared them with the clinical parameters of PD. METHODS: The study participants consisted of 66 sporadic PD patients and 52 controls. We measured serum GLA activity and calculated the apparent Michaelis constant (Km ) and maximal velocity (Vmax ) by Lineweaver-Burk plot analysis. Serum GLA protein concentration was measured by enzyme-linked immunosorbent assay. We examined the potential correlations between serum GLA activity and GLA protein concentration and clinical features and the plasma neurofilament light chain (NfL) level. RESULTS: Compared to controls, PD patients showed significantly lower serum GLA activity (P < 0.0001) and apparent Vmax (P = 0.0131), but no change in the apparent Km value. Serum GLA protein concentration was lower in the PD group (P = 0.0168) and was positively associated with GLA activity. Serum GLA activity and GLA protein concentration in the PD group showed a negative correlation with age. Additionally, serum GLA activity was negatively correlated with the motor severity score and the level of plasma NfL, and was positively correlated with the score of frontal assessment battery. INTERPRETATION: This study highlights that the lower serum GLA activity in PD is the result of a quantitative decrement of GLA protein in the serum and that it may serve as a biomarker of disease severity.

BACKGROUND: Parkinson's disease (PD) is associated with cognitive decline through multiple mechanisms, including Alzheimer's disease (AD) pathology and cortical Lewy body involvement. However, its underlying mechanisms remain unclear. Recently, AD-related plasma biomarkers have emerged as potential tools for predicting abnormal pathological protein accumulation. We aimed to investigate the association between AD-related plasma biomarkers and cognitive decline in PD patients. METHODS: Plasma biomarkers were measured in 70 PD patients (49 with nondemented Parkinson's disease (PDND) and 21 with Parkinson's disease dementia (PDD)) and 38 healthy controls (HCs) using a single-molecule array. The study evaluated (1) the correlation between plasma biomarkers and clinical parameters, (2) receiver operating characteristic curves and areas under the curve to evaluate the discrimination capacity of plasma biomarkers among groups, and (3) a generalized linear model to analyze associations with Addenbrooke's Cognitive Examination-Revised and Montreal Cognitive Assessment-Japanese version scores. RESULTS: Plasma glial fibrillary acidic protein significantly correlated with cognitive function tests, including all subdomains, with a notable increase in the PDD group compared with the HC and PDND groups, while plasma neurofilament light chain captured both cognitive decline and disease severity in the PDND and PDD groups. Plasma beta-amyloid 42/40 and pholphorylated-tau181 indicated AD pathology in the PDD group, but plasma beta-amyloid 42/40 was increased in the PDND group compared with HCs and decreased in the PDD group compared with the PDND group. CONCLUSIONS: AD-related plasma biomarkers may predict cognitive decline in PD and uncover underlying mechanisms suggesting astrocytic pathologies related to cognitive decline in PD.

This review summarizes improvements in understanding the pathophysiology and early clinical symptoms of multiple system atrophy (MSA) and advancements in diagnostic methods and disease-modifying therapies for the condition. In 2022, the Movement Disorder Society proposed new diagnostic criteria to develop disease-modifying therapies and promote clinical trials of MSA since the second consensus was proposed in 2008. Regarding pathogenesis, cutting-edge findings have accumulated on the interactions of α-synuclein, neuroinflammation, and oligodendroglia with neurons. In neuroimaging, introducing artificial intelligence, machine learning, and deep learning has notably improved diagnostic accuracy and individual analyses. Advancements in treatment have also been achieved, including immunotherapy therapy against α-synuclein and serotonin-targeted and mesenchymal stem cell therapies, which are thought to affect several aspects of the disease, including neuroinflammation. The accelerated progress in clarifying the pathogenesis of MSA over the past few years and the development of diagnostic techniques for detecting early-stage MSA are expected to facilitate the development of disease-modifying therapies for one of the most intractable neurodegenerative diseases.

Progressive encephalomyelitis with rigidity and myoclonus (PERM) is a severe form of stiff-person spectrum disorder. We report a 59-year-old man who presented with progressive encephalomyelitis causing diplopia, bulbar palsy, severe dysautonomia, followed by stiffness and myoclonic cluster. Laboratory tests showed mild pleocytosis, with markedly elevated plasma levels of norepinephrine, epinephrine, and arginine vasopressin. Glycine-receptor antibodies were identified in both serum and CSF. Despite a poor response to methylprednisolone, immunoglobulins, and plasma exchange, α-blocker stabilized dysautonomia. Dysautonomia is presumed to be due to antibody-mediated disinhibited sympathetic hyperactivity; however, this case suggests that concomitant use of α-blocker with immunotherapy may ameliorate dysautonomia.

Clioquinol has been implicated as a causative agent for subacute myelo-optico-neuropathy (SMON) in humans, although the mechanism remains to be elucidated. In this study, we utilized astrocyte-derived cell line, KT-5 cells to explore its potential cytotoxicity on glial cells. KT-5 cells were exposed in vitro to a maximum of 50 μM clioquinol for up to 24 h. 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenylte trazolium bromide (MTT) assay of the cells revealed that clioquinol induced significant cell damage and death. We also found that clioquinol caused accumulation of microtubule-associated protein light chain-3 (LC3)-II and sequestosome-1 (p62) in a dose- and time-dependent manner, suggesting the abnormality of autophagy-lysosome pathway. Consistent with these findings, an exposure of 20 μM clioquinol induced the accumulation of cellular autophagic vacuoles. Moreover, an exposure of 20 μM clioquinol provoked a statistically significant reduction of intracellular lysosomal acid hydrolases activities but no change in lysosomal pH. It also resulted in a significant decline of intracellular ATP levels, enhanced cellular levels of reactive oxygen species, and eventually cell death. This cell death at least did not appear to occur via apoptosis. 10 μM Chloroquine, lysosomal inhibitor, blocked the autophagic degradation and augmented clioquinol-cytotoxicity, whereas rapamycin, an inducer of autophagy, rescued clioquinol-induced cytotoxicity. Thus, our present results strongly suggest clioquinol acts as a potentially cytotoxic agent to glial cells. For future clinical application of clioquinol on the treatment of neurological and cancer disorders, we should take account of this type of cell death mechanism.

Cerebrospinal fluid (CSF) contains glycosphingolipids, including lactosylceramide (LacCer, Galβ(1,4)Glcβ-ceramide). LacCer and its structural isomer, galabiosylceramide (Gb2, Galα(1,4)Galβ-ceramide), are classified as ceramide dihexosides (CDH). Gb2 is degraded by α-galactosidase A (GLA) in lysosomes, and genetic GLA deficiency causes Fabry disease, an X-linked lysosomal storage disorder. In patients with Fabry disease, Gb2 accumulates in organs throughout the body. While Gb2 has been reported to be in the liver, kidney, and urine of healthy individuals, its presence in CSF has not been reported, either in patients with Fabry disease or healthy controls. Here, we isolated CDH fractions from CSF of patients with idiopathic normal pressure hydrocephalus. Purified CDH fractions showed positive reaction with Shiga toxin, which specifically binds to the Galα(1,4)Galβ structure. The isolated CDH fractions were analyzed by hydrophilic interaction chromatography (HILIC)-electrospray ionization tandem mass spectrometry (ESI-MS/MS). HILIC-ESI-MS/MS separated LacCer and Gb2 and revealed the presence of Gb2 and LacCer in the fractions. We also found Gb2 in CSF from neurologically normal control subjects. This is the first report to show Gb2 exists in human CSF.

To understand the mechanisms underlying preserved and impaired cognitive function in healthy aging and dementia, respectively, the spatial relationships of brain networks and mechanisms of their resilience should be understood. The hub regions of the brain, such as the multisensory integration and default mode networks, are critical for within- and between-network communication, remain well-preserved during aging, and play an essential role in compensatory processes. On the other hand, these brain hubs are the preferred sites for lesions in neurodegenerative dementias, such as Alzheimer's disease. Disrupted primary information processing networks, such as the auditory, visual, and sensorimotor networks, may lead to overactivity of the multisensory integration networks and accumulation of pathological proteins that cause dementia. At the cellular level, the brain hub regions contain many synapses and require a large amount of energy. These regions are rich in ATP-related gene expression and had high glucose metabolism as demonstrated on positron emission tomography (PET). Importantly, the number and function of mitochondria, which are the center of ATP production, decline by about 8% every 10 years. Dementia patients often have dysfunction of the ubiquitin-proteasome and autophagy-lysosome systems, which require large amounts of ATP. If there is low energy supply but the demand is high, the risk of disease can be high. Imbalance between energy supply and demand may cause accumulation of pathological proteins and play an important role in the development of dementia. This energy imbalance may explain why brain hub regions are vulnerable to damage in different dementias. Here, we review (1) the characteristics of gray matter network, white matter network, and resting state functional network changes related to resilience in healthy aging, (2) the mode of resting state functional network disruption in neurodegenerative dementia, and (3) the cellular mechanisms associated with the disruption.

BACKGROUND: As mutations in glucocerebrosidase 1 (GBA1) are a major risk factor for Parkinson's disease (PD), decreased GBA1 activity might play an important role in the pathogenesis of the disease. However, there are currently no reports on glucosylceramide levels in the cerebrospinal fluid (CSF) in PD. OBJECTIVE: We investigated whether glucosylceramide accumulation and abnormal immune status in the brain are associated with PD. METHODS: We measured glucosylceramide by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) as well as levels of the active fragment of complement C5, C5a, in the CSF of 33 PD, 15 amyotrophic lateral sclerosis (ALS) and 22 neurologically normal control (NNC) subjects. Serum C5a levels in all PD and ALS cases and in a limited number of NNC subjects (n = 8) were also measured. RESULTS: C5a levels in CSF were significantly downregulated in PD compared with NNC. Moreover, CSF C5a/serum C5a ratio showed pronounced perturbations in PD and ALS patients. LC-ESI-MS/MS revealed a statistically significant accumulation of a specific subspecies of glucosylceramide (d18 : 1/C23 : 0 acyl chain fatty acid) in ALS, but not in PD. Interestingly, CSF glucosylceramide (d18 : 1/C23 : 0) exhibited a significant correlation with CSF C5a levels in PD, but not ALS. No correlation was observed between C5a levels or glucosylceramide subspecies content and disease duration, levodopa equivalent daily dose or Hoehn & Yahr staging in PD. CONCLUSION: Our findings demonstrate complement dysregulation without glucosylceramide accumulation in PD CSF. Furthermore, we found an association between a specific glucosylceramide subspecies and immune status in PD.

Recently, the genetic variability in lysosomal storage disorders has been implicated in the pathogenesis of Parkinson's disease. Here, we found that variants in prosaposin (PSAP), a rare causative gene of various types of lysosomal storage disorders, are linked to Parkinson's disease. Genetic mutation screening revealed three pathogenic mutations in the saposin D domain of PSAP from three families with autosomal dominant Parkinson's disease. Whole-exome sequencing revealed no other variants in previously identified Parkinson's disease-causing or lysosomal storage disorder-causing genes. A case-control association study found two variants in the intronic regions of the PSAP saposin D domain (rs4747203 and rs885828) in sporadic Parkinson's disease had significantly higher allele frequencies in a combined cohort of Japan and Taiwan. We found the abnormal accumulation of autophagic vacuoles, impaired autophagic flux, altered intracellular localization of prosaposin, and an aggregation of α-synuclein in patient-derived skin fibroblasts or induced pluripotent stem cell-derived dopaminergic neurons. In mice, a Psap saposin D mutation caused progressive motor decline and dopaminergic neurodegeneration. Our data provide novel genetic evidence for the involvement of the PSAP saposin D domain in Parkinson's disease.