Neuroprotection and Disease Modification by Astrocytes and Microglia in Parkinson Disease.

Oxidative stress and neuroinflammation are common bases for disease onset and progression in many neurodegenerative diseases. In Parkinson disease, which is characterized by the degeneration of dopaminergic neurons resulting in dopamine depletion, the pathogenesis differs between hereditary and solitary disease forms and is often unclear. In addition to the pathogenicity of alpha-synuclein as a pathological disease marker, the involvement of dopamine itself and its interactions with glial cells (astrocyte or microglia) have attracted attention. Pacemaking activity, which is a hallmark of dopaminergic neurons, is essential for the homeostatic maintenance of adequate dopamine concentrations in the synaptic cleft, but it imposes a burden on mitochondrial oxidative glucose metabolism, leading to reactive oxygen species production. Astrocytes provide endogenous neuroprotection to the brain by producing and releasing antioxidants in response to oxidative stress. Additionally, the protective function of astrocytes can be modified by microglia. Some types of microglia themselves are thought to exacerbate Parkinson disease by releasing pro-inflammatory factors (M1 microglia). Although these inflammatory microglia may further trigger the inflammatory conversion of astrocytes, microglia may induce astrocytic neuroprotective effects (A2 astrocytes) simultaneously. Interestingly, both astrocytes and microglia express dopamine receptors, which are upregulated in the presence of neuroinflammation. The anti-inflammatory effects of dopamine receptor stimulation are also attracting attention because the functions of astrocytes and microglia are greatly affected by both dopamine depletion and therapeutic dopamine replacement in Parkinson disease. In this review article, we will focus on the antioxidative and anti-inflammatory effects of astrocytes and their synergism with microglia and dopamine.

Trousseau's Syndrome Presenting as Multiple Cerebral Infarctions Caused by Mucin-producing Bladder Micropapillary Urothelial Cancer.

We herein report a 70-year-old man with recurrent multiple cerebral infarctions under warfarin therapy who was finally diagnosed with Trousseau's syndrome resulting from advanced bladder cancer. A histological examination of the mesenteric lymph nodes revealed metastasis of micropapillary urothelial cancer with positive mucin markers CA125 and MUC1. Blood examinations also indicated elevated tumor markers, such as CA19-9 and CA125. To our knowledge, this is the first report of Trousseau's syndrome in a patient with bladder micropapillary urothelial cancer in which mucin involvement was clearly proven by histological and serological examinations.

Evaluation of [18F]PI-2620, a second-generation selective tau tracer, for assessing four-repeat tauopathies.

Tau aggregates represent a key pathologic feature of Alzheimer's disease and other neurodegenerative diseases. Recently, PET probes have been developed for in vivo detection of tau accumulation; however, they are limited because of off-target binding and a reduced ability to detect tau in non-Alzheimer's disease tauopathies. The novel tau PET tracer, [18F]PI-2620, has a high binding affinity and specificity for aggregated tau; therefore, it was hypothesized to have desirable properties for the visualization of tau accumulation in Alzheimer's disease and non-Alzheimer's disease tauopathies. To assess the ability of [18F]PI-2620 to detect regional tau burden in non-Alzheimer's disease tauopathies compared with Alzheimer's disease, patients with progressive supranuclear palsy (n = 3), corticobasal syndrome (n = 2), corticobasal degeneration (n = 1) or Alzheimer's disease (n = 8), and healthy controls (n = 7) were recruited. All participants underwent MRI, amyloid ß assessment and [18F]PI-2620 PET (Image acquisition at 60-90 min post-injection). Cortical and subcortical tau accumulations were assessed by calculating standardized uptake value ratios using [18F]PI-2620 PET. For pathologic validation, tau pathology was assessed using tau immunohistochemistry and compared with [18F]PI-2620 retention in an autopsied case of corticobasal degeneration. In Alzheimer's disease, focal retention of [18F]PI-2620 was evident in the temporal and parietal lobes, precuneus, and cingulate cortex. Standardized uptake value ratio analyses revealed that patients with non-Alzheimer's disease tauopathies had elevated [18F]PI-2620 uptake only in the globus pallidus, as compared to patients with Alzheimer's disease, but not healthy controls. A head-to-head comparison of [18F]PI-2620 and [18F]PM-PBB3, another tau PET probe for possibly visualizing the four-repeat tau pathogenesis in non-Alzheimer's disease, revealed different retention patterns in one subject with progressive supranuclear palsy. Imaging-pathology correlation analysis of the autopsied patient with corticobasal degeneration revealed no significant correlation between [18F]PI-2620 retention in vivo. High [18F]PI-2620 uptake at 60-90 min post-injection in the globus pallidus may be a sign of neurodegeneration in four-repeat tauopathy, but not necessarily practical for diagnosis of non-Alzheimer's disease tauopathies. Collectively, this tracer is a promising tool to detect Alzheimer's disease-tau aggregation. However, late acquisition PET images of [18F]PI-2620 may have limited utility for reliable detection of four-repeat tauopathy because of lack of correlation between post-mortem tau pathology and different retention pattern than the non-Alzheimer's disease-detectable tau radiotracer, [18F]PM-PBB3. A recent study reported that [18F]PI-2620 tracer kinetics curves in four-repeat tauopathies peak earlier (within 30 min) than Alzheimer's disease; therefore, further studies are needed to determine appropriate PET acquisition times that depend on the respective interest regions and diseases.

Human Astrocytes Model Derived from Induced Pluripotent Stem Cells.

Induced pluripotent stem cell (iPSC)-based disease modeling has a great potential for uncovering the mechanisms of pathogenesis, especially in the case of neurodegenerative diseases where disease-susceptible cells can usually not be obtained from patients. So far, the iPSC-based modeling of neurodegenerative diseases has mainly focused on neurons because the protocols for generating astrocytes from iPSCs have not been fully established. The growing evidence of astrocytes' contribution to neurodegenerative diseases has underscored the lack of iPSC-derived astrocyte models. In the present study, we established a protocol to efficiently generate iPSC-derived astrocytes (iPasts), which were further characterized by RNA and protein expression profiles as well as functional assays. iPasts exhibited calcium dynamics and glutamate uptake activity comparable to human primary astrocytes. Moreover, when co-cultured with neurons, iPasts enhanced neuronal synaptic maturation. Our protocol can be used for modeling astrocyte-related disease phenotypes in vitro and further exploring the contribution of astrocytes to neurodegenerative diseases.

The utility of simple questions to evaluate cognitive impairment.

OBJECTIVES: As the population of patients with cognitive decline grows, physicians and caregivers need brief screening tools. Comprehensive neurocognitive batteries require special training and time for evaluation. We focused on accessibility and compared the diagnostic power of several easy questions. DESIGN: "Attended With" (AW) and "Head-Turning Sign" (HTS) factors and participants' replies to following questions were recorded: "Do you feel that you have more difficulties in your daily life than you used to?", [no consciousness (C-) or consciousness+ (C+)], "Could you tell me about your daily pleasures or pastimes?" [no pleasure (P-) or pleasure + (P+)], "What are notable current/recent news/topics?" [no news (N-) or news+ (N+)]. SETTING: This took place in our Memory Clinic between May 2016 and July 2019. PARTICIPANTS: We enrolled 162 consecutive cases (44 cognitive normal (CN), 55 amnestic mild cognitive impairment (aMCI), and 48 Alzheimer's disease (AD)). MEASUREMENTS: The sensitivity and specificity of each battery were calculated, and on account of those numbers, the population attributable risk percent % (PAR%) of (AW and HTS+), (C- and P-), (C- and N-), (P- and N-) as analysis of combination of questions, respectively, were calculated. RESULTS: AW had high sensitivity, 87.4, 95.8% (CN vs aMCI + AD, CN + aMCI vs AD) but the sensitivity of HTS was only 46.4, 57.7%, and HTS showed high specificity, 100.0, 71.8%. C- had high sensitivity, 80.6, 87.5%, whereas P- and N- had high specificity, both 83.9% in CN vs aMCI + AD, 88.1% and 75.9% in CN + aMCI vs AD, respectively. In combination analysis, the PAR% of (C- and N-) were as high as (AW and HTS+). CONCLUSIONS: The combination of (C- and N-) is as powerful as (AW and HTS+) in screening AD. Our findings provide novel insights for screening utility of brief questions "Consciousness of Impairment" and "Recent News."

Author Correction: De novo design of RNA-binding proteins with a prion-like domain related to ALS/FTD proteinopathies.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Identification and Characterization of Apigenin 6-C-Glucosyltransferase Involved in Biosynthesis of Isosaponarin in Wasabi (Eutrema japonicum).

Wasabi (Eutrema japonicum) is a perennial plant native to Japan that is used as a spice because it contains isothiocyanates. It also contains an isosaponarin, 4'-O-glucosyl-6-C-glucosyl apigenin, in its leaves, which has received increasing attention in recent years for its bioactivity, such as its promotion of type-I collagen production. However, its biosynthetic enzymes have not been clarified. In this study, we partially purified a C-glucosyltransferase (CGT) involved in isosaponarin biosynthesis from wasabi leaves and identified the gene coding for it (WjGT1). The encoded protein was similar to UGT84 enzymes and was named UGT84A57. The recombinant enzyme of WjGT1 expressed in Escherichia coli showed C-glucosylation activity toward the 6-position of flavones such as apigenin and luteolin. The enzyme also showed significant activity toward flavonols, but trace or no activity toward flavone 4'-O-glucosides, suggesting that isosaponarin biosynthesis in wasabi plants would proceed by 6-C-glucosylation of apigenin, followed by its 4'-O-glucosylation. Interestingly, the enzyme showed no activity against sinapic acid or p-coumaric acid, which are usually the main substrates of UGT84 enzymes. The accumulation of WjGT1 transcripts was observed mainly in the leaves and flowers of wasabi, in which C-glucosylflavones were accumulated. Molecular phylogenetic analysis suggested that WjGT1 acquired C-glycosylation activity independently from other reported CGTs after the differentiation of the family Brassicaceae.

Neuroprotective Role of Astroglia in Parkinson Disease by Reducing Oxidative Stress Through Dopamine-Induced Activation of Pentose-Phosphate Pathway.

Oxidative stress plays an important role in the onset and progression of Parkinson disease. Although released dopamine at the synaptic terminal is mostly reabsorbed by dopaminergic neurons, some dopamine is presumably taken up by astroglia. This study examined the dopamine-induced astroglial protective function through the activation of the pentose-phosphate pathway (PPP) to reduce reactive oxygen species (ROS). In vitro experiments were performed using striatal neurons and cortical or striatal astroglia prepared from Sprague-Dawley rats or C57BL/6 mice. The rates of glucose phosphorylation in astroglia were evaluated using the [14C]deoxyglucose method. PPP activity was measured using [1-14C]glucose and [6-14C]glucose after acute (60 min) or chronic (15 hr) exposure to dopamine. ROS production was measured using 2',7'-dichlorodihydrofluorescein diacetate. The involvement of the Kelch-like ECH-associated protein 1 (Keap1) or nuclear factor-erythroid-2-related factor 2 (Nrf2) system was evaluated using Nrf2 gene knockout mice, immunohistochemistry, and quantitative reverse transcription polymerase chain reaction analysis for heme oxygenase-1. Acute exposure to dopamine elicited increases in astroglial glucose consumption with lactate release. PPP activity in astroglia was robustly enhanced independently of Na+-dependent monoamine transporters. In contrast, chronic exposure to dopamine induced moderate increases in PPP activity via the Keap1/Nrf2 system. ROS production from dopamine increased gradually over 12 hr. Dopamine induced neuronal cell damage that was prevented by coculturing with astroglia but not with Nrf2-deficient astroglia. Dopamine-enhanced astroglial PPP activity in both acute and chronic manners may possibly reduce neuronal oxidative stress.

De novo design of RNA-binding proteins with a prion-like domain related to ALS/FTD proteinopathies.

Aberrant RNA-binding proteins form the core of the neurodegeneration cascade in spectrums of disease, such as amyotrophic lateral sclerosis (ALS)/frontotemporal dementia (FTD). Six ALS-related molecules, TDP-43, FUS, TAF15, EWSR1, heterogeneous nuclear (hn)RNPA1 and hnRNPA2 are RNA-binding proteins containing candidate mutations identified in ALS patients and those share several common features, including harboring an aggregation-prone prion-like domain (PrLD) containing a glycine/serine-tyrosine-glycine/serine (G/S-Y-G/S)-motif-enriched low-complexity sequence and rich in glutamine and/or asparagine. Additinally, these six molecules are components of RNA granules involved in RNA quality control and become mislocated from the nucleus to form cytoplasmic inclusion bodies (IBs) in the ALS/FTD-affected brain. To reveal the essential mechanisms involved in ALS/FTD-related cytotoxicity associated with RNA-binding proteins containing PrLDs, we designed artificial RNA-binding proteins harboring G/S-Y-G/S-motif repeats with and without enriched glutamine residues and nuclear-import/export-signal sequences and examined their cytotoxicity in vitro. These proteins recapitulated features of ALS-linked molecules, including insoluble aggregation, formation of cytoplasmic IBs and components of RNA granules, and cytotoxicity instigation. These findings indicated that these artificial RNA-binding proteins mimicked features of ALS-linked molecules and allowed the study of mechanisms associated with gain of toxic functions related to ALS/FTD pathogenesis.

Extremely Low Prevalence of Amyloid Positron Emission Tomography Positivity in Parkinson's Disease without Dementia.

BACKGROUND: Most cases of dementia with Lewy bodies (DLB) show Alzheimer's disease pathology-like senile plaques and neurofibrillary tangles. Several studies have also revealed a high prevalence of positive amyloid imaging with positron emission tomography (PET) in DLB and moderate prevalence in Parkinson's disease (PD) with dementia. However, it remains unclear in PD without dementia as to when the brain ß amyloid (Aß) burden begins and progresses. Our study aimed to determine the prevalence of Aß deposition in PD without dementia using amyloid PET. METHODS: This was a cross-sectional study on 33 patients with PD without dementia, of whom 21 had normal cognition and 12 met the criteria for PD-mild cognitive impairment. All subjects underwent neuropsychological assessment and [18F] florbetaben (FBB) PET. RESULTS: All subjects had Lewy body-related disorders, displaying a significantly reduced myocardial [123I] metaiodobenzylguanidine uptake. The cortical FBB-binding pattern in all subjects, including APOE e4 carriers, suggested negative Aß deposition. CONCLUSION: Patients with PD without dementia exhibit an extremely low prevalence of Aß positivity compared with those reported in cognitively normal elderly controls. Further longitudinal imaging studies and long-term follow-up are needed; however, our findings provide novel insights for understanding Aß metabolism in PD.

A possible role of microglia-derived nitric oxide by lipopolysaccharide in activation of astroglial pentose-phosphate pathway via the Keap1/Nrf2 system.

BACKGROUND: Toll-like receptor 4 (TLR4) plays a pivotal role in the pathophysiology of stroke-induced inflammation. Both astroglia and microglia express TLR4, and endogenous ligands produced in the ischemic brain induce inflammatory responses. Reactive oxygen species (ROS), nitric oxide (NO), and inflammatory cytokines produced by TLR4 activation play harmful roles in neuronal damage after stroke. Although astroglia exhibit pro-inflammatory responses upon TLR4 stimulation by lipopolysaccharide (LPS), they may also play cytoprotective roles via the activation of the pentose phosphate pathway (PPP), reducing oxidative stress by glutathione peroxidase. We investigated the mechanisms by which astroglia reduce oxidative stress via the activation of PPP, using TLR4 stimulation and hypoxia in concert with microglia. METHODS: In vitro experiments were performed using cells prepared from Sprague-Dawley rats. Coexisting microglia in the astroglial culture were chemically eliminated using L-leucine methyl ester (LME). Cells were exposed to LPS (0.01 µg/mL) or hypoxia (1 % O2) for 12-15 h. PPP activity was measured using [1-(14)C]glucose and [6-(14)C]glucose. ROS and NO production were measured using 2',7'-dichlorodihydrofluorescein diacetate and diaminofluorescein-FM diacetate, respectively. The involvement of nuclear factor-erythroid-2-related factor 2 (Nrf2), a cardinal transcriptional factor under stress conditions that regulates glucose 6-phosphate dehydrogenase, the rate-limiting enzyme of PPP, was evaluated using immunohistochemistry. RESULTS: Cultured astroglia exposed to LPS elicited 20 % increases in PPP flux, and these actions of astroglia appeared to involve Nrf2. However, the chemical depletion of coexisting microglia eliminated both increases in PPP and astroglial nuclear translocation of Nrf2. LPS induced ROS and NO production in the astroglial culture containing microglia but not in the microglia-depleted astroglial culture. LPS enhanced astroglial ROS production after glutathione depletion. U0126, an upstream inhibitor of mitogen-activated protein kinase, eliminated LPS-induced NO production, whereas ROS production was unaffected. U0126 also eliminated LPS-induced PPP activation in astroglial-microglial culture, indicating that microglia-derived NO mediated astroglial PPP activation. Hypoxia induced astroglial PPP activation independent of the microglia-NO pathway. Elimination of ROS and NO production by sulforaphane, a natural Nrf2 activator, confirmed the astroglial protective mechanism. CONCLUSIONS: Astroglia in concert with microglia may play a cytoprotective role for countering oxidative stress in stroke.

Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) after treatment for Hodgkin's lymphoma.

Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) is a rare central nervous system (CNS) disorder with distinct radiological features. However, CLIPPERS may mimic CNS lymphoma, and several cases in which CLIPPERS occurred premonitory to CNS lymphoma have been reported. We report a 31-year-old man presenting with progressive gait ataxia and the characteristic MRI features of CLIPPERS. He was diagnosed with stage II Hodgkin's lymphoma at the age of 15, and we considered the possibility of newly emerged CNS lymphoma occurring in the immunosuppressive condition after the treatment of Hodgkin's lymphoma. Histological findings showed no evidence of CNS lymphoma and the neurological symptoms were resolved by steroids. Although CLIPPERS developed in the reverse order in this case, CLIPPERS should be considered in different diagnosis for CNS lymphoma.

Roles and regulation of ketogenesis in cultured astroglia and neurons under hypoxia and hypoglycemia.

Exogenous ketone bodies (KBs), acetoacetate (AA), and ß-hydroxybutyrate (BHB) act as alternative energy substrates in neural cells under starvation. The present study examined the endogenous ketogenic capacity of astroglia under hypoxia with/without glucose and the possible roles of KBs in neuronal energy metabolism. Cultured neurons and astroglia were prepared from Sprague-Dawley rats. Palmitic acid (PAL) and l-carnitine (LC) were added to the assay medium. The 4- to 24-hr production of AA and BHB was measured using the cyclic thio-NADH method. (14)C-labeled acid-soluble products (KBs) and (14)CO2 produced from [1-(14)C]PAL were also measured. l-[U-(14)C]lactic acid ([(14)C]LAC), [1-(14)C]pyruvic acid ([(14)C]PYR), or ß-[1-(14)C]hydroxybutyric acid ([(14)C]BHB) was used to compare the oxidative metabolism of the glycolysis end products with that of the KBs. Some cells were placed in a hypoxic chamber (1% O2). PAL and LC induced a higher production of KBs in astroglia than in neurons, while the CO2 production from PAL was less than 5% of the KB production in both astroglia and neurons. KB production in astroglia was augmented by the AMP-activated protein kinase activators, AICAR and metformin, as well as hypoxia with/without glucose. Neuronal KB production increased under hypoxia in the absence of PAL and LC. In neurons, [(14)C]LAC and [(14)C]PYR oxidation decreased after 24 hr of hypoxia, while [(14)C]BHB oxidation was preserved. Astroglia responds to ischemia in vitro by enhancing KB production, and astroglia-produced KBs derived from fatty acid might serve as a neuronal energy substrate for the tricarboxylic acid cycle instead of lactate, as pyruvate dehydrogenase is susceptible to ischemia.

Cellular origin and regulation of D- and L-serine in in vitro and in vivo models of cerebral ischemia.

D-Serine is known to be essential for the activation of the N-methyl-D-aspartate (NMDA) receptor in the excitation of glutamatergic neurons, which have critical roles in long-term potentiation and memory formation. D-Serine is also thought to be involved in NMDA receptor-mediated neurotoxicity. The deletion of serine racemase (SRR), which synthesizes D-serine from L-serine, was recently reported to improve ischemic damage in mouse middle cerebral artery occlusion model. However, the cell type in which this phenomenon originates and the regulatory mechanism for D-/L-serine remain elusive. The D-/L-serine content in ischemic brain increased until 20 hours after recanalization and then leveled off gradually. The results of in vitro experiments using cultured cells suggested that D-serine is derived from neurons, while L-serine seems to be released from astroglia. Immunohistochemistry studies of brain tissue after cerebral ischemia showed that SRR is expressed in neurons, and 3-phosphoglycerate dehydrogenase (3-PGDH), which synthesizes L-serine from 3-phosphoglycerate, is located in astrocytes, supporting the results of the in vitro experiments. A western blot analysis showed that neither SRR nor 3-PGDH was upregulated after cerebral ischemia. Therefore, the increase in D-/L-serine was not related to an increase in SRR or 3-PGDH, but to an increase in the substrates of SRR and 3-PGDH.