Stage-dependent immunity orchestrates AQP4 antibody-guided NMOSD pathology: a role for netting neutrophils with resident memory T cells in situ.

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease of the CNS characterized by the production of disease-specific autoantibodies against aquaporin-4 (AQP4) water channels. Animal model studies suggest that anti-AQP4 antibodies cause a loss of AQP4-expressing astrocytes, primarily via complement-dependent cytotoxicity. Nonetheless, several aspects of the disease remain unclear, including: how anti-AQP4 antibodies cross the blood-brain barrier from the periphery to the CNS; how NMOSD expands into longitudinally extensive transverse myelitis or optic neuritis; how multiphasic courses occur; and how to prevent attacks without depleting circulating anti-AQP4 antibodies, especially when employing B-cell-depleting therapies. To address these knowledge gaps, we conducted a comprehensive 'stage-dependent' investigation of immune cell elements in situ in human NMOSD lesions, based on neuropathological techniques for autopsied/biopsied CNS materials. The present study provided three major findings. First, activated or netting neutrophils and melanoma cell adhesion molecule-positive (MCAM+) helper T (TH) 17/cytotoxic T (TC) 17 cells are prominent, and the numbers of these correlate with the size of NMOSD lesions in the initial or early-active stages. Second, forkhead box P3-positive (FOXP3+) regulatory T (Treg) cells are recruited to NMOSD lesions during the initial, early-active or late-active stages, suggesting rapid suppression of proinflammatory autoimmune events in the active stages of NMOSD. Third, compartmentalized resident memory immune cells, including CD103+ tissue-resident memory T (TRM) cells with long-lasting inflammatory potential, are detected under "standby" conditions in all stages. Furthermore, CD103+ TRM cells express high levels of granzyme B/perforin-1 in the initial or early-active stages of NMOSD in situ. We infer that stage-dependent compartmentalized immune traits orchestrate the pathology of anti-AQP4 antibody-guided NMOSD in situ. Our work further suggests that targeting activated/netting neutrophils, MCAM+ TH17/TC17 cells, and CD103+ TRM cells, as well as promoting the expansion of FOXP3+ Treg cells, may be effective in treating and preventing relapses of NMOSD.

Genome-wide association study identifies a new susceptibility locus in PLA2G4C for Multiple System Atrophy.

To elucidate the molecular basis of multiple system atrophy (MSA), a neurodegenerative disease, we conducted a genome-wide association study (GWAS) in a Japanese MSA case/control series followed by replication studies in Japanese, Korean, Chinese, European and North American samples. In the GWAS stage rs2303744 on chromosome 19 showed a suggestive association ( P = 6.5 × 10 -7 ) that was replicated in additional Japanese samples ( P = 2.9 × 10 -6 . OR = 1.58; 95% confidence interval, 1.30 to 1.91), and then confirmed as highly significant in a meta-analysis of East Asian population data ( P = 5.0 × 10 -15 . Odds ratio= 1.49; 95% CI 1.35 to 1.72). The association of rs2303744 with MSA remained significant in combined European/North American samples ( P =0.023. Odds ratio=1.14; 95% CI 1.02 to 1.28) despite allele frequencies being quite different between these populations. rs2303744 leads to an amino acid substitution in PLA2G4C that encodes the cPLA2γ lysophospholipase/transacylase. The cPLA2γ-Ile143 isoform encoded by the MSA risk allele has significantly decreased transacylase activity compared with the alternate cPLA2γ-Val143 isoform that may perturb membrane phospholipids and α-synuclein biology.

Importance of the Q/N-rich segment for protein stability of endogenous mouse TDP-43.

TAR DNA-binding protein 43 kDa (TDP-43), a nuclear protein, plays an important role in the molecular pathogenesis of amyotrophic lateral sclerosis (ALS). The long-disordered C-terminal region (CTR) of TDP-43 is known to be aggregation-prone and a hotspot for ALS mutations, so elucidation of the physiological function of CTR will provide insights into the pathogenesis of ALS. The CTR has two Gly, aromatic, and Ser-rich (GaroS) segments and an amyloidogenic core divided into a hydrophobic patch (HP) and a Gln/Asn (Q/N)-rich segment. Although TDP-43 lacking the CTR is known to be unstable, as observed in knock-in mice, it is unclear which of these segments contributes to the stability of TDP-43. Here, we generated 12 mouse lines lacking the various sub-regions of CTR by genome editing and compared the embryonic lethality of homozygotes, and protein and mRNA expression levels of TDP-43. We demonstrated the functional diversity of the four segments of CTR, finding that the presence of the Q/N-rich segment greatly restored the protein stability of TDP-43. In addition, we found that the second GaroS deletion did not affect protein stability and mouse development.

Candesartan prevents arteriopathy progression in cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy model.

Cerebral small vessel disease (CSVD) causes dementia and gait disturbance due to arteriopathy. Cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL) is a hereditary form of CSVD caused by loss of high-temperature requirement A1 (HTRA1) serine protease activity. In CARASIL, arteriopathy causes intimal thickening, smooth muscle cell (SMC) degeneration, elastic lamina splitting, and vasodilation. The molecular mechanisms were proposed to involve the accumulation of matrisome proteins as substrates or abnormalities in transforming growth factor ß (TGF-ß) signaling. Here, we show that HTRA1-/- mice exhibited features of CARASIL-associated arteriopathy: intimal thickening, abnormal elastic lamina, and vasodilation. In addition, the mice exhibited reduced distensibility of the cerebral arteries and blood flow in the cerebral cortex. In the thickened intima, matrisome proteins, including the hub protein fibronectin (FN) and latent TGF-ß binding protein 4 (LTBP-4), which are substrates of HTRA1, accumulated. Candesartan treatment alleviated matrisome protein accumulation and normalized the vascular distensibility and cerebral blood flow. Furthermore, candesartan reduced the mRNA expression of Fn1, Ltbp-4, and Adamtsl2, which are involved in forming the extracellular matrix network. Our results indicate that these accumulated matrisome proteins may be potential therapeutic targets for arteriopathy in CARASIL.

[Primary Central Nervous System Lymphoma: How Do Neurologists Deal with its Management?]

What are desirable roles of general neurologists in the diagnosis and treatment of primary central nervous system lymphoma (PCNSL)? These issues were discussed 7 years back in the special feature articles of this journal. In the last 7 years genome analyses using liquid biopsy specimens have progressed and are becoming popular in the management of PCNSL, thereby enabling neurosurgeons to avoid invasive brain biopsy. The role of general neurologists in this country is not to be directly engaged in the PCNSL management, but to make an early diagnosis of PCNSL and to refer patients with PCNSL to specialists for a combination of chemotherapy and irradiation therapy.

Assessment of Ataxia Rating Scales and Cerebellar Functional Tests: Critique and Recommendations.

BACKGROUND: We assessed the clinimetric properties of ataxia rating scales and functional tests, and made recommendations regarding their use. METHODS: A systematic literature search was conducted to identify the instruments used to rate ataxia symptoms. The identified rating scales and functional ability tests were reviewed and ranked by the panel as "recommended," "suggested," or "listed" for the assessment of patients with discrete cerebellar disorders, using previously established criteria. RESULTS: We reviewed 14 instruments (9 rating scales and 5 functional tests). "Recommended" rating scales for the assessment of symptoms severity were: for Friedreich's ataxia, the Friedreich's Ataxia Rating Scale, the International Cooperative Ataxia Rating Scale (ICARS), and the Scale for the Assessment and Rating of Ataxia (SARA); for spinocerebellar ataxias, ICARS and SARA; for ataxia telangiectasia: ICARS and SARA; for brain tumors, SARA; for congenital disorder of glycosylation-phosphomannomutase-2 deficiency, ICARS; for cerebellar symptoms in multiple sclerosis, ICARS; for cerebellar symptoms in multiple system atrophy: Unified Multiple System Atrophy Rating Scale and ICARS; and for fragile X-associated tremor ataxia syndrome, ICARS. "Recommended" functional tests were: for Friedreich's ataxia, Ataxia Functional Composite Score and Composite Cerebellar Functional Severity Score; and for spinocerebellar ataxias, Ataxia Functional Composite Score, Composite Cerebellar Functional Severity Score, and SCA Functional Index. CONCLUSIONS: We identified some "recommended" scales and functional tests for the assessment of patients with major hereditary ataxias and other cerebellar disorders. The main limitations of these instruments include the limited assessment of patients in the more severe end of the spectrum and children. Further research in these populations is warranted. © 2020 International Parkinson and Movement Disorder Society.

TDP-43 transports ribosomal protein mRNA to regulate axonal local translation in neuronal axons.

Mislocalization and abnormal deposition of TDP-43 into the cytoplasm (TDP-43 proteinopathy) is a hallmark in neurons of amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). However, the pathogenic mechanism of the diseases linked to TDP-43 is largely unknown. We hypothesized that the failure of mRNA transport to neuronal axons by TDP-43 may contribute to neurodegeneration in ALS and FTLD, and sought to examine the function of TDP-43 by identifying its target mRNA for axonal transport. We found that mRNAs related to translational function including ribosomal proteins (RPs) were decreased by shRNA-based TDP-43 knock-down in neurites of cortical neurons. TDP-43 binds to and transports the RP mRNAs through their 5' untranslated region, which contains a common 5' terminal oligopyrimidine tract motif and a downstream GC-rich region. We showed by employing in vitro and in vivo models that the RP mRNAs were translated and incorporated into native ribosomes locally in axons to maintain functionality of axonal ribosomes, which is required for local protein synthesis in response to stimulation and stress to axons. We also found that RP mRNAs were reduced in the pyramidal tract of sporadic ALS cases harboring TDP-43 pathology. Our results elucidated a novel function of TDP-43 to control transport of RP mRNAs and local translation by ribosomes to maintain morphological integrity of neuronal axons, and proved the influence of this function of TDP-43 on neurodegeneration in ALS and FTLD associated with TDP-43 proteinopathy.

[What is the Medical Professionalism for Japanese Clinical Neurologists?]

Fundamental principles of medical ethics or medical professionalism in Western countries greatly influence our country, particularly in the field of medical education. Talent/ competency of physicians, included in the multiple domains of medical professionalism, is now employed as an outcome measure of medical education. In this review, I would like to discuss what is the most essential issue of medical professionalism and medical education for Japanese clinical neurologists and what philosophy we should hand over to our successors. Among various elemental factors in medical professionalism, I regard "empathy" as the most important, which empowers patients and their families.

Effect of rovatirelin in patients with cerebellar ataxia: two randomised double-blind placebo-controlled phase 3 trials.

OBJECTIVE: To investigate the efficacy of rovatirelin, a thyrotropin-releasing hormone analogue, for ataxias in patients with spinocerebellar degeneration (SCD). METHODS: Two multicentre, randomised, double-blind, placebo-controlled phase 3 studies (KPS1301, KPS1305) enrolled patients with predominant cerebellar ataxia, including SCA6, SCA31 or cortical cerebellar atrophy. KPS1301 enrolled patients with truncal ataxia and KPS1305 enrolled patients with truncal and limb ataxia. Each study included 4 weeks of pretreatment, a 28-week or 24-week treatment period and 4 weeks of follow-up. Patients were randomised (1:1:1) to rovatirelin (1.6 or 2.4 mg) or placebo in KPS1301, and randomised (1:1) to rovatirelin 2.4 mg or placebo in KPS1305. The primary endpoint was change in Scale for the Assessment and Rating of Ataxia (SARA) total scores. Pooled analysis was performed in patients who met the SARA recruitment criteria of KPS1305. RESULTS: From October 2013 to May 2014, KPS1301 enrolled 411 patients; 374 were randomised to rovatirelin 1.6 mg (n=125), rovatirelin 2.4 mg (n=126) or placebo (n=123). From November 2016 to August 2017, KPS1305 enrolled 241 patients; 203 were randomised to rovatirelin 2.4 mg (n=101) or placebo (n=102). The primary endpoint showed no significant difference between rovatirelin and placebo in these two studies. In the pooled analysis (n=278), the difference between rovatirelin 2.4 mg (n=140) and placebo (n=138) was -0.61 (-1.64 vs -1.03; 95% CI -1.16 to -0.06; p=0.029) in the adjusted mean change in the SARA total score. CONCLUSIONS: Rovatirelin is a potentially effective treatment option for SCD. TRIAL REGISTRATION NUMBER: NCT01970098; NCT02889302.

Predictors of cognitive impairment in multiple system atrophy.

OBJECTIVE: To determine predictors of cognitive impairment and frontal dysfunction in patients with multiple system atrophy (MSA). METHODS: We recruited 59 patients with MSA and determined the predictors of a decline in the Mini-Mental State Examination (MMSE) and Frontal Assessment Battery (FAB) scores. RESULTS: The MMSE scores negatively correlated with disease duration, Unified MSA Rating Scale (UMSARS) part 1 and 4 scores, and residual urine volume, and positively correlated with the coefficient of variation of electrocardiographic RR intervals. The FAB scores negatively correlated with the UMSARS part 2 score, periventricular hyperintensity grade, and deep white matter hyperintense signal grade. A significant predictor of rapidly progressive cognitive impairment was a high residual urine volume. CONCLUSIONS: Impairment of global cognitive function correlates with the long-term disease duration, global disability due to the disease, and autonomic dysfunction, whereas frontal dysfunction correlates with motor function and degeneration of cerebral white matter.

Expansions of intronic TTTCA and TTTTA repeats in benign adult familial myoclonic epilepsy.

Epilepsy is a common neurological disorder, and mutations in genes encoding ion channels or neurotransmitter receptors are frequent causes of monogenic forms of epilepsy. Here we show that abnormal expansions of TTTCA and TTTTA repeats in intron 4 of SAMD12 cause benign adult familial myoclonic epilepsy (BAFME). Single-molecule, real-time sequencing of BAC clones and nanopore sequencing of genomic DNA identified two repeat configurations in SAMD12. Intriguingly, in two families with a clinical diagnosis of BAFME in which no repeat expansions in SAMD12 were observed, we identified similar expansions of TTTCA and TTTTA repeats in introns of TNRC6A and RAPGEF2, indicating that expansions of the same repeat motifs are involved in the pathogenesis of BAFME regardless of the genes in which the expanded repeats are located. This discovery that expansions of noncoding repeats lead to neuronal dysfunction responsible for myoclonic tremor and epilepsy extends the understanding of diseases with such repeat expansion.

Loss of Motor Neurons Innervating Cervical Muscles in Patients With Multiple System Atrophy and Dropped Head.

We investigated whether loss of motor neurons innervating the neck muscles contributes to dropped head (DH) in multiple system atrophy (MSA). From 75 patients with autopsy-proven MSA, we retrieved 3 who had DH (MSA-DH), and examined the 4th cervical cord segments. Neurons of the medial and lateral nuclear groups (MNG and LNG) innervate the neck and shoulder muscles, respectively. We measured the area of individual neurons in the MNG and LNG, and created an area-frequency histogram. Neurons were classified as large or small based on their area, and their total numbers in the MNG and LNG were counted. In the MNG, the numbers of both total neurons and large neurons were significantly lower in MSA patients than in the controls (214.2 ± 91.4 vs 521.3 ± 74.8, p = 0.0030, and 26.2 ± 9.1 vs 88.0 ± 34.6, p = 0.020, respectively), and were significantly lower in MSA-DH than in MSA-nonDH (139.7 ± 7.6 vs 288.7 ± 74.6, p = 0.048, and 18.0 ± 4.1 vs 34.3 ± 4.1, p = 0.016, respectively). There were no differences in the LNG neuron counts between the MSA-DH and MSA-nonDH groups. Loss of cervical motor neurons may be responsible for DH in MSA.

Case Report: A patient with spinocerebellar ataxia type 31 and sporadic Creutzfeldt-Jakob disease.

We report a Japanese patient with spinocerebellar ataxia type 31 (SCA31) and sporadic Creutzfeldt-Jakob disease (sCJD). A 52-year-old man developed progressive cognitive impairment after the appearance of cerebellar symptoms. Brain MR diffusion-weighted imaging (DWI) demonstrated a slowly expanding hyperintense lesion in the cerebral cortex. The patient was finally diagnosed as having both SCA31 and sCJD by identification of genetic mutations and by real-time quaking-induced conversion (RT-QUIC) analysis of the cerebrospinal fluid (CSF), respectively. Here, we report the clinical details of this rare combined case, with particular reference to the association between prion protein and the early onset of SCA31.

Apparent diffusion coefficient reduction might be a predictor of poor outcome in patients with posterior reversible encephalopathy syndrome.

It is thought that posterior reversible encephalopathy syndrome (PRES) is both clinically and radiologically reversible. However, its reversible nature has been challenged based on reports of permanent neurological impairments. The factors that predict the development of irreversible neurological impairment are still unclear. In the present study, we investigated clinical manifestations, laboratory findings, and neuroradiological images to identify predictors of functional outcomes in PRES. We investigated 23 PRES patients. Apparent diffusion coefficient (ADC) reduction was observed in 4 patients in the poor outcome group, whereas no patients presented ADC reduction in the favourable outcome group (p<0.01). Further studies are warranted to evaluate the association between ADC reduction and functional outcome after PRES.

The Clinical Features, Risk Factors, and Surgical Treatment of Cervicogenic Headache in Patients With Cervical Spine Disorders Requiring Surgery.

OBJECTIVE: To clarify the clinical features and risk factors of cervicogenic headache (CEH; as diagnosed according to the International Classification of Headache Disorders-Third Edition beta) in patients with cervical spine disorders requiring surgery. BACKGROUND: CEH is caused by cervical spine disorders. The pathogenic mechanism of CEH is hypothesized to involve a convergence of the upper cervical afferents from the C1, C2, and C3 spinal nerves and the trigeminal afferents in the trigeminocervical nucleus of the upper cervical cord. According to this hypothesis, functional convergence of the upper cervical and trigeminal sensory pathways allows the bidirectional (afferent and efferent) referral of pain to the occipital, frontal, temporal, and/or orbital regions. Previous prospective studies have reported an 86-88% prevalence of headache in patients with cervical myelopathy or radiculopathy requiring anterior cervical surgery; however, these studies did not diagnose headache according to the International Classification of Headache Disorders criteria. Therefore, a better understanding of the prevalence rate, clinical features, risk factors, and treatment responsiveness of CEH in patients with cervical spine disorders requiring surgery is necessary. METHODS: We performed a single hospital-based prospective cross-sectional study and enrolled 70 consecutive patients with cervical spine disorders such as cervical spondylotic myelopathy, ossification of the posterior longitudinal ligament, cervical spondylotic radiculopathy, and cervical spondylotic myeloradiculopathy who had been scheduled to undergo anterior cervical fusion or dorsal cervical laminoplasty between June 2014 and December 2015. Headache was diagnosed preoperatively according to the International Classification of Headache Disorders-Third Edition beta. The Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire, Neck Disability Index, and a 0-100 mm visual analog scale (VAS) were used to evaluate clinical features, and scores were compared between baseline (ie, preoperatively) and 3, 6, and 12 months post-surgery. RESULTS: The prevalence of CEH in our population was 15/70 (21.4%, 95%CI: 11.8% to 31.0%). The main clinical features were dull and tightening/pressing headache sensations in the occipital region. Headache severity was mild (VAS, 32 ± 11 mm) and only one patient reported use of an oral analgesic. Compared to patients without CEH, patients with CEH had higher frequencies of neck pain (86.7% vs. 50.9%; P = .017), cervical range of motion limitation (ROM) (66.7% vs. 38.2%; P = .049), and higher Neck Disability Index scores (14 vs. 3; P < .001). Among the different cervical spine disorders, the prevalence of CEH was highest in cervical spondylotic myeloradiculopathy patients (60%), being ≤ 20% for all other disorders. Surgical treatments including cervical laminoplasty to relieve abnormal pressure on the spinal cord via a posterior approach, were associated with initial improvements in headache VAS that slightly diminished by 12 months post-surgery (P < .001). CONCLUSIONS: We report a lower prevalence of CEH in patients with cervical spinal disorders requiring surgery than that reported previously. The main clinical features of CEH were mild, dull, and tightening/pressing headache sensations in the occipital region. Potential risk factors for CEH included neck pain, limited cervical ROM, high Neck Disability Index score, and a diagnosis of cervical spondylotic myeloradiculopathy. The further accumulation of patients in a multi-institutional study may be required in order to discuss the diagnostic criteria and pathophysiology of this condition.

Natural course and potential prognostic factors for sleep-disordered breathing in multiple system atrophy.

OBJECTIVE/BACKGROUND: Multiple system atrophy (MSA) frequently results in the development of sleep-disordered breathing (SDB). Few reports have described the natural course of this phenomenon. The aim of the present study was to determine the natural course of SDB and prognostic factors associated with such conditions in MSA. PATIENTS/METHODS: Twenty-four consecutive patients were recruited with probable MSA, who had not been treated with continuous positive airway pressure (CPAP) and had undergone overnight polysomnography (PSG) more than once following the development of snoring or stridor. Based on changes in the apnea-hypopnea index (AHI) over the course of the disease, patients were divided into two groups (AHI-maintained and AHI-deteriorated) and the clinical findings were compared. RESULTS: Mean duration between the first and last PSG was 2.4 ± 1.5 years, and patients underwent PSG assessment an average of 2.5 ± 0.6 times during this period. During this interval, AHI increased from 19.4 ± 22.8/hour to 34.4 ± 30.1/hour (p = 0.006), although spontaneous improvement was observed in 29% of patients. Following the first PSG, all patients were diagnosed with obstructive sleep apnea; however, the SDB type changed from obstructive sleep apnea to central sleep apnea in 3 of the 24 (13%) patients during the period between the first and last PSG. CONCLUSIONS: Although SDB associated with MSA exacerbates with disease progression, spontaneous improvement in AHI may occur in some patients. Earlier development of snoring or stridor may predict rapid progression of SDB in MSA.

Microglia preconditioned by oxygen-glucose deprivation promote functional recovery in ischemic rats.

Cell-therapies that invoke pleiotropic mechanisms may facilitate functional recovery in stroke patients. We hypothesized that a cell therapy using microglia preconditioned by optimal oxygen-glucose deprivation (OGD) is a therapeutic strategy for ischemic stroke because optimal ischemia induces anti-inflammatory M2 microglia. We first delineated changes in angiogenesis and axonal outgrowth in the ischemic cortex using rats. We found that slight angiogenesis without axonal outgrowth were activated at the border area within the ischemic core from 7 to 14 days after ischemia. Next, we demonstrated that administration of primary microglia preconditioned by 18 hours of OGD at 7 days prompted functional recovery at 28 days after focal cerebral ischemia compared to control therapies by marked secretion of remodelling factors such as vascular endothelial growth factor, matrix metalloproteinase-9, and transforming growth factor-ß polarized to M2 microglia in vitro/vivo. In conclusion, intravascular administration of M2 microglia preconditioned by optimal OGD may be a novel therapeutic strategy against ischemic stroke.

Methylmercury Causes Blood-Brain Barrier Damage in Rats via Upregulation of Vascular Endothelial Growth Factor Expression.

Clinical manifestations of methylmercury (MeHg) intoxication include cerebellar ataxia, concentric constriction of visual fields, and sensory and auditory disturbances. The symptoms depend on the site of MeHg damage, such as the cerebellum and occipital lobes. However, the underlying mechanism of MeHg-induced tissue vulnerability remains to be elucidated. In the present study, we used a rat model of subacute MeHg intoxication to investigate possible MeHg-induced blood-brain barrier (BBB) damage. The model was established by exposing the rats to 20-ppm MeHg for up to 4 weeks; the rats exhibited severe cerebellar pathological changes, although there were no significant differences in mercury content among the different brain regions. BBB damage in the cerebellum after MeHg exposure was confirmed based on extravasation of endogenous immunoglobulin G (IgG) and decreased expression of rat endothelial cell antigen-1. Furthermore, expression of vascular endothelial growth factor (VEGF), a potent angiogenic growth factor, increased markedly in the cerebellum and mildly in the occipital lobe following MeHg exposure. VEGF expression was detected mainly in astrocytes of the BBB. Intravenous administration of anti-VEGF neutralizing antibody mildly reduced the rate of hind-limb crossing signs observed in MeHg-exposed rats. In conclusion, we demonstrated for the first time that MeHg induces BBB damage via upregulation of VEGF expression at the BBB in vivo. Further studies are required in order to determine whether treatment targeted at VEGF can ameliorate MeHg-induced toxicity.

Expression of Aquaporin 1 and Aquaporin 4 in the Temporal Neocortex of Patients with Parkinson's Disease.

The astrocytic water channel proteins aquaporin 1 (AQP1) and aquaporin 4 (AQP4) are known to be altered in brains affected by several neurodegenerative disorders, including Alzheimer's disease. However, AQP expression in brains affected by Parkinson's disease (PD) has not been described in detail. Recently, it has been reported that α-synuclein (α-syn)-immunolabeled astrocytes show preferential distribution in several cerebral regions, including the neocortex, in patients with PD. Here, we investigated whether AQP expression is associated with α-syn deposition in the temporal neocortex of PD patients. In accordance with the consensus criteria for dementia with Lewy bodies, the patients were classified into neocortical (PDneo), limbic (PDlim), and brain stem (PDbs) groups. Expressions of α-syn, AQP1, and AQP4 in the temporal lobes of the individual PD patients were examined immunohistochemically. Immunohistochemical analysis demonstrated more numerous AQP4-positive and AQP1-positive astrocytes in the PDneo group than in the PDbs, PDlim, and control groups. However, in the PDneo cases, these astrocytes were not often observed in α-syn-rich areas, and semiquantitative analysis revealed that there was a significant negative correlation between the levels of AQP4 and α-syn in layers V-VI, and between those of AQP1 and α-syn in layers II-III. These findings suggest that a defined population of AQP4- and AQP1-expressing reactive astrocytes may modify α-syn deposition in the neocortex of patients with PD.