Kei-Ichi Ishikawa

Analyses of the MAPT, PGRN, and C9orf72 mutations in Japanese patients with FTLD, PSP, and CBS

BACKGROUND Mutations in the microtubule associated protein tau (MAPT) and progranulin (PGRN) have been identified in several neurodegenerative disorders, such as frontotemporal lobar degeneration (FTLD), progressive supranuclear palsy (PSP), and corticobasal syndrome (CBS). Recently, C9orf72 repeat expansion was reported to cause FTLD and amyotrophic lateral sclerosis (ALS). To date, no comprehensive analyses of mutations in these three genes have been performed in Asian populations. The aim of this study was to investigate the genetic and clinical features of Japanese patients with MAPT, PGRN, or C9orf72 mutations. METHODS MAPT and PGRN were analyzed by direct sequencing and gene dosage assays, and C9orf72 repeat expansion was analyzed by repeat-primed PCR in 75 (48 familial, 27 sporadic) Japanese patients with FTLD, PSP, or CBS. RESULTS We found four MAPT mutations in six families, one novel PGRN deletion/insertion, and no repeat expansion in C9orf72. Intriguingly, we identified a de novo MAPT p.S285R mutation. All six patients with early-onset PSP and the abnormal eye movements that are not typical of sporadic PSP had MAPT mutations. The gene dosages of MAPT and PGRN were normal. DISCUSSION MAPT p.S285R is the first reported de novo mutation in a sporadic adult-onset patient. MAPT mutation analysis is recommended in both familial and sporadic patients, especially in early-onset PSP patients with these abnormal eye movements. Although PGRN and C9orf72 mutations were rare in this study, the PGRN mutation was found in this Asian FTLD. These genes should be studied further to improve the clinicogenetic diagnoses of FTLD, PSP, and CBS.

Serum Uric Acid Concentration is Linked to Wearing-off Fluctuation in Japanese Parkinson's Disease Patients

BACKGROUND Serum uric acid (UA) concentration is linked to the risk of progression of Parkinsons disease (PD). OBJECTIVES The aim of this study was to examine the association between serum UA concentration and the occurrence of wearing-off fluctuation (WOF) in Japanese PD patients. METHODS A total of 123 Japanese patients with PD were enrolled in this study. We collected data on demographics, clinical features, medications, and laboratory findings including serum UA concentration, and examined the presence of WOF. The association between serum UA concentration and WOF was assessed using multivariate logistic regression analysis. RESULTS After adjusting for possible confounders, it was found that the odds ratio (OR) for WOF decreased with increasing quartile of UA (highest quartile vs. lowest quartile, adjusted OR 0.218, 95% confidence interval [CI] 0.053-0.891). This association was significant only in male PD patients, regardless of the use of sex-specific quartiles of UA. Additionally, disease duration (OR 7.80, 95% CI 2.62-23.17) and daily levodopa dosage (OR 4.06, 95% CI 1.45-11.38) were associated with the occurrence of WOF. CONCLUSIONS Our results showed that serum UA concentration was associated with the occurrence of WOF. Serum UA concentration may be a predictive factor for WOF.

Effective control of catatonia in Parkinson’s disease by electroconvulsive therapy: a case report

Catatonia is a psychomotor syndrome, including mutism, immobility, rigidity, negativism, catalepsy and echophenomena. Although catatonia has been reported to occur in many illnesses [1], there have been few reports in the literature of catatonia in Parkinson s disease (PD). We describe a rare case of a patient with PD who developed catatonia during the course of the disease. The patient was a 75-year-old woman. At age 71 years, she was diagnosed with idiopathic PD and treatment with levodopa/carbidopa (300 mg/day) and cabergoline (4 mg/day) initiated. At age 74 years, levodopa/carbidopa was increased to 400 mg/day and cabergoline was switched to pramipexole (3 mg/day) because of motor fluctuations, and talipexole (0.4 mg/day) was added at bedtime to control sleep disturbance [2] as well as nocturnal akinesia. At age 75 years, she experienced hallucinations and complained of dyspnoea with anxiety in the off state. Subsequently, the patient was admitted to our hospital for adjustment of her medications. Neurological examination showed that she was alert with somatic and persecutory delusion in addition to visual, auditory and olfactory hallucinations, which appeared to be late complications of PD [3]. She had no dementia. Hoehn and Yahr stage was 3 and 4 in the on and off state, respectively. To control the psychiatric disorders and motor fluctuations, the dose of levodopa/ carbidopa was increased to 650 mg/day and entacapone (700 mg/day) was added, while pramipexole and talipexole were withdrawn. Several days after altering the medication, the patient went into a peculiar state in which she did not follow any commands in the morning. The status included mutism, immobility, rigidity, negativism and catalepsy. She readily recovered from the status after administration of levodopa via a nasogastric tube, although she was unable to take levodopa orally in a standard way because of the immobility and negativism. Based on the characteristic phenomenology, we diagnosed the disorder as catatonia. Neuroleptic malignant-like syndrome or acute akinesia was ruled out in the absence of fever, infection, dehydration, perspiration, creatine phosphokinase (CPK) elevation and refractoriness to administration of levedopa [4]. A trial of therapy aimed at stimulating various receptors such as droxydopa, clonazepam, donepezil and paroxetine was ineffective for catatonia. Because the use of an indwelling nasogastric tube is unpleasant and impractical at home, we decided to use electroconvulsive therapy (ECT). Two successive ECT alleviated the catatonia as well as the psychiatric problems and motor fluctuations. Although the pathomechanism of catatonia remains poorly understood, dysregulation of dopaminergic system could play a role [5]. Alleviation of catatonia by levodopa in our case might provide support to this hypothesis. In the only previously reported PD case with catatonia other than our patient, catatonia occurred following administration of neuroleptics for psychosis [6], further supporting the possible role of dopaminergic hypoactivity in catatonia at least in PD. Neurologists are often in a dilemma when treating PD patients with psychosis, i.e. dopaminergic treatment for parkinsonism can result in exacerbation of psychosis. In this context, ECT can be a promising therapeutic option, which has been reported to be effective for motor symptoms in PD and psychiatric comorbidity [7]. Although the mechanism by which ECT exhibits its effectiveness still remains elusive, neurologists should consider ECT as a therapeutic option when they encounter dilemmatic PD patients, that is, those with psychiatric comorbidity including catatonia.

Decreased long-chain acylcarnitines from insufficient β-oxidation as potential early diagnostic markers for Parkinson’s disease

Increasing evidence shows that metabolic abnormalities in body fluids are distinguishing features of the pathophysiology of Parkinson’s disease. However, a non-invasive approach has not been established in the earliest or pre-symptomatic phases. Here, we report comprehensive double-cohort analyses of the metabolome using capillary electrophoresis/liquid chromatography mass-spectrometry. The plasma analyses identified 18 Parkinson’s disease-specific metabolites and revealed decreased levels of seven long-chain acylcarnitines in two Parkinson’s disease cohorts (n = 109, 145) compared with controls (n = 32, 45), respectively. Furthermore, statistically significant decreases in five long-chain acylcarnitines were detected in Hoehn and Yahr stage I. Likewise, decreased levels of acylcarnitine(16:0), a decreased ratio of acylcarnitine(16:0) to fatty acid(16:0), and an increased index of carnitine palmitoyltransferase 1 were identified in Hoehn and Yahr stage I of both cohorts, suggesting of initial β-oxidation suppression. Receiver operating characteristic curves produced using 12–14 long-chain acylcarnitines provided a large area of under the curve, high specificity and moderate sensitivity for diagnosing Parkinson’s disease. Our data demonstrate that a primary decrement of mitochondrial β-oxidation and that 12–14 long-chain acylcarnitines decreases would be promising diagnostic biomarkers for Parkinson’s disease.

p150glued-Associated Disorders Are Caused by Activation of Intrinsic Apoptotic Pathway

Mutations in p150glued cause hereditary motor neuropathy with vocal cord paralysis (HMN7B) and Perry syndrome (PS). Here we show that both overexpression of p150glued mutants and knockdown of endogenous p150glued induce apoptosis. Overexpression of a p150glued plasmid containing either a HMN7B or PS mutation resulted in cytoplasmic p150glued-positive aggregates and was associated with cell death. Cells containing mutant p150glued aggregates underwent apoptosis that was characterized by an increase in cleaved caspase-3- or Annexin V-positive cells and was attenuated by both zVAD-fmk (a pan-caspase inhibitor) application and caspase-3 siRNA knockdown. In addition, overexpression of mutant p150glued decreased mitochondrial membrane potentials and increased levels of translocase of the mitochondrial outer membrane (Tom20) protein, indicating accumulation of damaged mitochondria. Importantly, siRNA knockdown of endogenous p150glued independently induced apoptosis via caspase-8 activation and was not associated with mitochondrial morphological changes. Simultaneous knockdown of endogenous p150glued and overexpression of mutant p150glued had additive apoptosis induction effects. These findings suggest that both p150glued gain-of-toxic-function and loss-of-physiological-function can cause apoptosis and may underlie the pathogenesis of p150glued-associated disorders.

Serum caffeine and metabolites are reliable biomarkers of early Parkinson disease

Objective To investigate the kinetics and metabolism of caffeine in serum from patients with Parkinson disease (PD) and controls using liquid chromatography–mass spectrometry. Methods Levels of caffeine and its 11 metabolites in serum from 108 patients with PD and 31 age-matched healthy controls were examined by liquid chromatography–mass spectrometry. Mutations in caffeine-associated genes were screened by direct sequencing. Results Serum levels of caffeine and 9 of its downstream metabolites were significantly decreased even in patients with early PD, unrelated to total caffeine intake or disease severity. No significant genetic variations in CYP1A2 or CYP2E1, encoding cytochrome P450 enzymes primarily involved in metabolizing caffeine in humans, were detected compared with controls. Likewise, caffeine concentrations in patients with PD with motor complications were significantly decreased compared with those without motor complications. No associations between disease severity and single nucleotide variants of the ADORA2A gene encoding adenosine 2A receptor were detected, implying a dissociation of receptor sensitivity changes and phenotype. The profile of serum caffeine and metabolite levels was identified as a potential diagnostic biomarker by receiver operating characteristic curve analysis. Conclusion Absolute lower levels of caffeine and caffeine metabolite profiles are promising diagnostic biomarkers for early PD. This is consistent with the neuroprotective effect of caffeine previously revealed by epidemiologic and experimental studies. Classification of evidence This study provides Class III evidence that decreased serum levels of caffeine and its metabolites identify patients with PD.

Ethambutol neutralizes lysosomes and causes lysosomal zinc accumulation

Ethambutol is a common medicine used for the treatment of tuberculosis, which can have serious side effects, such as retinal and liver dysfunction. Although ethambutol has been reported to impair autophagic flux in rat retinal cells, the precise molecular mechanism remains unclear. Using various mammalian cell lines, we showed that ethambutol accumulated in autophagosomes and vacuolated lysosomes, with marked Zn(2+) accumulation. The enlarged lysosomes were neutralized and were infiltrated with Zn(2+) accumulations in the lysosomes, with simultaneous loss of acidification. These results suggest that EB neutralizes lysosomes leading to insufficient autophagy, implying that some of the adverse effects associated with EB in various organs may be of this mechanism.

Soluble epoxide hydrolase plays a key role in the pathogenesis of Parkinson’s disease

Significance Parkinson’s disease (PD) is a chronic and progressive movement disorder; however, the precise mechanisms of its etiology remain largely unknown. Soluble epoxide hydrolase (sEH) plays a key role in the inflammation associated with PD pathogenesis. The sEH inhibitor or deletion of the sEH gene protected against MPTP-induced neurotoxicity in mouse brain. Furthermore, expression of the sEH protein (or mRNA) was higher in the striatum of MPTP-treated mice, patients with dementia of Lewy bodies (DLB), and neurons from iPSCs of a PD patient with PARKIN mutations. Interestingly, treatment with sEH inhibitor protected against apoptosis in human PARK2 iPSC-derived dopaminergic neurons. Our findings indicate that sEH inhibitors or epoxy fatty acids mimics may be promising prophylactic or therapeutic drugs for PD. Parkinson’s disease (PD) is characterized as a chronic and progressive neurodegenerative disorder, and the deposition of specific protein aggregates of α-synuclein, termed Lewy bodies, is evident in multiple brain regions of PD patients. Although there are several available medications to treat PD symptoms, these medications do not prevent the progression of the disease. Soluble epoxide hydrolase (sEH) plays a key role in inflammation associated with the pathogenesis of PD. Here we found that MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-induced neurotoxicity in the mouse striatum was attenuated by subsequent repeated administration of TPPU, a potent sEH inhibitor. Furthermore, deletion of the sEH gene protected against MPTP-induced neurotoxicity, while overexpression of sEH in the striatum significantly enhanced MPTP-induced neurotoxicity. Moreover, the expression of the sEH protein in the striatum from MPTP-treated mice or postmortem brain samples from patients with dementia of Lewy bodies (DLB) was significantly higher compared with control groups. Interestingly, there was a positive correlation between sEH expression and phosphorylation of α-synuclein in the striatum. Oxylipin analysis showed decreased levels of 8,9-epoxy-5Z,11Z,14Z-eicosatrienoic acid in the striatum of MPTP-treated mice, suggesting increased activity of sEH in this region. Interestingly, the expression of sEH mRNA in human PARK2 iPSC-derived neurons was higher than that of healthy control. Treatment with TPPU protected against apoptosis in human PARK2 iPSC-derived dopaminergic neurons. These findings suggest that increased activity of sEH in the striatum plays a key role in the pathogenesis of neurodegenerative disorders such as PD and DLB. Therefore, sEH may represent a promising therapeutic target for α-synuclein–related neurodegenerative disorders.

Effects of donepezil dose escalation in Parkinson's patients with dementia receiving long-term donepezil treatment: an exploratory study

The benefits of escalating the dose of donepezil in patients who are already receiving long‐term treatment with it have not been well evaluated. Therefore, an exploratory study to assess the effects of donepezil dose escalation in patients with Parkinsons disease with dementia, and specifically on patients receiving long‐term treatment with donepezil, was performed.

p150glued deficiency impairs effective fusion between autophagosomes and lysosomes due to their redistribution to the cell periphery

Dynein-dynactin has an indispensable role in autophagy and p150glued is the largest component of the dynactin complex. Here, we characterized the effects of knockdown (KD) of endogenous p150glued and of the pathogenic mutation of p150glued found in autosomal dominant p150glued-associated disorders [hereditary motor neuronopathy with vocal paresis (HMN7B) and Perry syndrome] on autophagy. Overexpression of the p150glued pathogenic mutant or siRNA KD of p150glued promoted the localization of lysosomes at the cell periphery and increased the number of autophagosomes, suggesting partial blockage of autophagic flux. Surprisingly, although autophagosomes and lysosomes were redistributed predominantly to the cell periphery in p150glued-KD cells, the autolysosome formation ratio was preserved. However, under autophagy activation conditions induced by starvation, the ratio of autophagosome-lysosome fusion in p150glued-KD cells was decreased in the early phase. Our data demonstrate that functional loss of p150glued may cause autophagic insufficiency, which may be associated with the pathogenesis of p150glued-associated disorders.