Analyses of natural courses of Japanese patients with Alzheimer's disease using placebo data from placebo-controlled, randomized clinical trials: Japanese Study on the Estimation of Clinical course of Alzheimer's disease

Introduction

Symptomatic anti-Alzheimer's disease (AD) drugs have been commonly used for the treatment of AD. Knowing the natural courses of patients with AD on placebo is highly relevant for clinicians to understand their efficacy and for investigators to design clinical studies.

Methods

The data on rating scales for dementia such as Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) and Severe Impairment Battery were extracted from eight previous Japanese Phase II and III studies. Natural courses of Japanese AD patients in placebo groups were evaluated and statistically analyzed in a pooled and retrospective fashion.

Results

Decreases in ADAS-cog and Severe Impairment Battery was larger at week 22 or 24 than at week 12. Scores of ADAS-cog appeared to deteriorate faster in moderate AD than in mild AD.

Discussion

The present data will provide clinicians following up patients with AD with helpful information on how to manage AD patients and investigators with instruction for clinical study design.

Distinct binding of PET ligands PBB3 and AV-1451 to tau fibril strains in neurodegenerative tauopathies

Diverse neurodegenerative disorders are characterized by deposition of tau fibrils composed of conformers (i.e. strains) unique to each illness. The development of tau imaging agents has enabled visualization of tau lesions in tauopathy patients, but the modes of their binding to different tau strains remain elusive. Here we compared binding of tau positron emission tomography ligands, PBB3 and AV-1451, by fluorescence, autoradiography and homogenate binding assays with homologous and heterologous blockades using tauopathy brain samples. Fluorescence microscopy demonstrated intense labelling of non-ghost and ghost tangles with PBB3 and AV-1451, while dystrophic neurites were more clearly detected by PBB3 in brains of Alzheimer's disease and diffuse neurofibrillary tangles with calcification, characterized by accumulation of all six tau isoforms. Correspondingly, partially distinct distributions of autoradiographic labelling of Alzheimer's disease slices with 11C-PBB3 and 18F-AV-1451 were noted. Neuronal and glial tau lesions comprised of 4-repeat isoforms in brains of progressive supranuclear palsy, corticobasal degeneration and familial tauopathy due to N279K tau mutation and 3-repeat isoforms in brains of Pick's disease and familial tauopathy due to G272V tau mutation were sensitively detected by PBB3 fluorescence in contrast to very weak AV-1451 signals. This was in line with moderate 11C-PBB3 versus faint 18F-AV-1451 autoradiographic labelling of these tissues. Radioligand binding to brain homogenates revealed multiple binding components with differential affinities for 11C-PBB3 and 18F-AV-1451, and higher availability of binding sites on progressive supranuclear palsy tau deposits for 11C-PBB3 than 18F-AV-1451. Our data indicate distinct selectivity of PBB3 compared to AV-1451 for diverse tau fibril strains. This highlights the more robust ability of PBB3 to capture wide-range tau pathologies.

HLA-DRB1*14 and DQB1*05 are associated with Japanese anti-MuSK antibody-positive myasthenia gravis patients

BACKGROUND

Myasthenia gravis (MG) is an autoimmune disorder presumed to be associated with genetic susceptibility. This study aims to determine whether HLA is associated with MG in Japanese patients.

METHODS

We included 58 MG patients with anti-acetylcholine receptor antibody (AChR+MG) and 14 MG patients with muscle-specific receptor tyrosine kinase (MuSK+MG) and determined HLA-A, B, DRB1 and -DQB1 alleles using polymerase chain reaction with sequence-specific oligonucleotide and primers. AChR+MG was classified into the three subgroups: early-onset MG (EOMG; n=11), late-onset MG (LOMG; n=20), and thymoma-associated MG (n=27). Healthy volunteers (n=100) served as controls.

RESULTS

A significant positive association was observed between MuSK+MG with the DRB1*14 [57.1%, MuSK+MG vs. 18.0%, healthy controls (HC); odds ratio (OR): 6.1] and DQB1*05 [78.6%, MuSK+MG vs. 30.0%, HC; odds ratio (OR): 8.5]. We found a negative association between LOMG and DQB1*04 [5.0%, LOMG vs. 37.0%, HC; OR: 0.09]. There was no association between other MG subgroups and HLA alleles.

CONCLUSION

HLA-DRB1*14 and DQB1*05 were associated with MuSK+MG, therefore these alleles may play important roles in developing MuSK+MG across the races.

Does Anticholinergic Activity Affect Neuropathology? Implication of Neuroinflammation in Alzheimer's Disease

One characteristic neuropathological feature of Alzheimer's disease (AD) is profound neuronal loss in the nucleus basalis of Meynert, the major source of cholinergic innervation of the cerebral cortex. Clinically, anticholinergic activity causes a decline in cognitive function and increases the risk of dementia, thus possibly enhancing AD pathologies and neurodegeneration. Until now there has been insufficient human neuropathological data to support this conclusion. Experimental studies using a tauopathy mouse model demonstrated anticholinergics enhanced tau pathology and neurodegeneration corresponding to central anticholinergic activity. Additionally, donepezil, a cholinesterase inhibitor, ameliorated tau pathology and neurodegeneration in the same mouse model. These results indicate the balance between cholinergic and anticholinergic activities might affect neurodegeneration. Importantly, neurodegeneration observed in the mouse model seemed to correspond to the distribution of microglial activation, and it was reported that neuroinflammation plays an important role in the pathomechanism of AD, while anticholinergic activity augments inflammatory responses. Moreover, some studies indicated β-amyloid itself depletes cholinergic function similarly to anticholinergic activity. Thus, anticholinergic activity might initiate and/or accelerate AD pathology. Limited human data support the conclusion that anticholinergic activity enhances AD-related neuropathology and neurodegeneration. However, experimental data from a tauopathy mouse model indicated anticholinergic activity might enhance neurodegeneration with enhanced neuroinflammation including microglial activation.

[Cognitive Function and Calcium. Suppression of neurotoxicity by an anti-dementia drug managing calcium influx]

Although drugs affecting N-methyl-D-aspartate (NMDA) receptors are being largely expected for anti-dementia drugs, memantine has been solely approved. As memantine has moderate affinity to NMDA receptors, memantine display efficacy of neuro-protection and learning promotion. In clinical trials, memantine showed suppression of progression of symptoms with dementia including improvement and suppression of aggressiveness and behavioral disturbance. Moreover, memantine can be prescribed with choline esterase inhibitors, thus, memantine is used as one of major anti-dementia drugs.

Effects of diet-induced obesity and voluntary exercise in a tauopathy mouse model: implications of persistent hyperleptinemia and enhanced astrocytic leptin receptor expression

The number of patients with Alzheimer's disease (AD) is increasing worldwide, and available drugs have shown limited efficacy. Hence, preventive interventions and treatments for presymptomatic AD are currently considered very important. Obesity rates have also been increasing dramatically and it is an independent risk factor of AD. Therefore, for the prevention of AD, it is important to elucidate the pathomechanism between obesity and AD. We generated high calorie diet (HCD)-induced obese tauopathy model mice (PS19), which showed hyperleptinemia but limited insulin resistance. HCD enhanced tau pathology and glial activation. Conversely, voluntary exercise with a running wheel normalized the serum leptin concentration without reducing body weight, and restored the pathological changes induced by HCD. Thus, we speculated that persistent hyperleptinemia played an important role in accelerating pathological changes in PS19 mice. Leptin primarily regulates food intake and body weight via leptin receptor b (LepRb). Interestingly, the nuclear staining for p-STAT3, which was activated by LepRb, was decreased in hippocampal neurons in HCD PS19 mice, indicating leptin resistance. Meanwhile, astroglial activation and the astrocytic expression of a short LepR isoform, LepRa, were enhanced in the hippocampus of HCD PS19 mice. Real-time PCR analysis demonstrated that leptin increased mRNA levels for pro-inflammatory cytokines including IL-1β and TNF-α in primary cultured astrocytes from wild type and LepRb-deficient mice. These observations suggest that persistent hyperleptinemia caused by obesity induces astrocytic activation, astrocytic leptin hypersensitivity with enhanced LepRa expression, and enhanced inflammation, consequently accelerating tau pathology in PS19 mice.

Therapeutic strategies for tau mediated neurodegeneration

Based on the amyloid hypothesis, controlling β-amyloid protein (Aβ) accumulation is supposed to suppress downstream pathological events, tau accumulation, neurodegeneration and cognitive decline. However, in recent clinical trials, Aβ removal or reducing Aβ production has shown limited efficacy. Moreover, while active immunisation with Aβ resulted in the clearance of Aβ, it did not prevent tau pathology or neurodegeneration. This prompts the concern that it might be too late to employ Aβ targeting therapies once tau mediated neurodegeneration has occurred. Therefore, it is timely and very important to develop tau directed therapies. The pathomechanisms of tau mediated neurodegeneration are unclear but hyperphosphorylation, oligomerisation, fibrillisation and propagation of tau pathology have been proposed as the likely pathological processes that induce loss of function or gain of toxic function of tau, causing neurodegeneration. Here we review the strategies for tau directed treatments based on recent progress in research on tau and our understanding of the pathomechanisms of tau mediated neurodegeneration.

Anti-inflammatory action of donepezil ameliorates tau pathology, synaptic loss, and neurodegeneration in a tauopathy mouse model

Acetylcholinesterase inhibitors (AChEIs) are widely used to compensate for acetylcholine (ACh) depletion in the Alzheimer's disease (AD) brain. Some clinical and experimental studies, however, have suggested that AChEIs also provide neuroprotection. To assess the effect of AChEIs on neurodegeneration, donepezil (DZ), an AChEI, was administered to FTDP-17 model mice with a P301S tau mutation (line PS19). Eight months of DZ treatment resulted in amelioration of neuroinflammation, tau pathology, synaptic loss, and neuronal loss, as well as decreased tau insolubility and phosphorylation. Tau kinase activity analysis demonstrated significantly suppressed c-Jun N-terminal kinase (JNK) in the brains of DZ-treated PS19 mice. Recently, ACh has been shown to suppress inflammation, which plays a role in neurodegeneration. To confirm the anti-inflammatory effect of DZ, PS19 mice were injected with lipopolysaccharide, in combination with or without DZ, for one month. Results demonstrated that DZ suppressed IL-1β and COX-2 expression in the brain, as well as the spleen, suggesting that DZ directly prevents systemic inflammation. These data indicated that ACh did not act just as a cognition-linking neurotransmitter, but might suppress pathological mechanisms of neurodegeneration via anti-inflammatory action.

Flexion-induced cervical myelopathy associated with fewer elastic fibers and thickening in the posterior dura mater

Two patients with a condition clinically resembling juvenile muscular atrophy of distal upper extremity (Hirayama disease) showed forward protrusive movement of the posterior cervical dura matter during neck flexion. The dura displacement was characteristically limited in an approximately central portion of the posterior dura, which is different from Hirayama disease, which exhibits whole posterior dura displacement. Interestingly, the restricted dura in these patients showed thickening with reduced elastic fibers, indicating that the decreased stretchability of the posterior dura had caused motor dominant cervical myelopathy.

[Neurodegeneration and inflammation: analysis of a FTDP-17 model mouse]

Filamentous tau inclusions are hallmarks of Alzheimer's disease (AD) and related tauopathies, and the discovery of mutations in the tau gene in frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) constitutes convincing evidence that tau proteins play a key role in the pathogenesis of neurodegenerative disorders. To investigate the pathomechanism of tauopathies, we generated and studied P301S mutant human tau transgenic mice (line PS19). Filamentous tau lesions developed in PS19 mice at 6-months of age, and progressively accumulated in association with striking neuron loss as well as hippocampal and entorhinal cortical atrophy by 9-12 months of age. Remarkably, hippocampal synapse loss and impaired synaptic function were detected in 3 month old PS19 mice before fibrillary tau tangles emerged. Prominent microglial activation and proinflammatory cytokine expressions in neurons also preceded tangle formation. Importantly, immunosuppression of young PS19 mice with FK506 attenuated tau pathology, thereby linking neuroinflammation to early progression of tauopathies. Recently, an anti-inflammatory function of acetylcholine (ACh) has been reported, suggesting that synaptic dysfunction might accelerate neuroinflammatory reaction by depletion of ACH. To investigate this, we administered donepezil (DZ), an ACh-esterase inhibitor, and trihexiphenidyl (TP), an anti-cholinergic agent to PS19 mice. Interestingly, DZ ameliorated but TP deteriorated microglial activation, tau pathology and neuronal loss, indicating the ACh level in the brain might play roles in not only neurotransmission, but also suppressing neuroinflammation in the brain.

Neuromyelitis optica and anti-aquaporin-4 antibodies measured by an enzyme-linked immunosorbent assay

NMO-IgG, a disease-specific autoantibody for neuromyelitis optica, recognizes aquaporin-4 (AQP4) and has been examined by indirect immunofluorescence assay. We developed an enzyme-linked immunosorbent assay (ELISA) to detect anti-AQP4 antibodies by establishing methods for expression in a baculovirus system and purification of recombinant AQP4 as antigen. Elevated anti-AQP4 antibody titers in serum were found in 15 (71%) of 21 patients with neuromyelitis optica, 4.3% of 46 patients with multiple sclerosis, none of 51 normal controls, and 2.6% of 115 patients with other neurological diseases. The ELISA system can be substituted for the conventional NMO-IgG assay.

Synapse loss and microglial activation precede tangles in a P301S tauopathy mouse model

Filamentous tau inclusions are hallmarks of Alzheimer's disease (AD) and related tauopathies, but earlier pathologies may herald disease onset. To investigate this, we studied wild-type and P301S mutant human tau transgenic (Tg) mice. Filamentous tau lesions developed in P301S Tg mice at 6 months of age, and progressively accumulated in association with striking neuron loss as well as hippocampal and entorhinal cortical atrophy by 9-12 months of age. Remarkably, hippocampal synapse loss and impaired synaptic function were detected in 3 month old P301S Tg mice before fibrillary tau tangles emerged. Prominent microglial activation also preceded tangle formation. Importantly, immunosuppression of young P301S Tg mice with FK506 attenuated tau pathology and increased lifespan, thereby linking neuroinflammation to early progression of tauopathies. Thus, hippocampal synaptic pathology and microgliosis may be the earliest manifestations of neurodegenerative tauopathies, and abrogation of tau-induced microglial activation could retard progression of these disorders.

Axonal degeneration induced by targeted expression of mutant human tau in oligodendrocytes of transgenic mice that model glial tauopathies

Abundant filamentous tau inclusions in oligodendrocytes (OLGs) are hallmarks of neurodegenerative tauopathies, including sporadic corticobasal degeneration and hereditary frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17). However, mechanisms of neurodegeneration in these tauopathies are unclear in part because of the lack of animal models for experimental analysis. We address this by generating transgenic (Tg) mice expressing human tau exclusively in OLGs using the 2',3'-cyclic nucleotide 3'-phosphodiesterase promoter. Filamentous OLG tau inclusions developed in these Tg mice as a result of human tau expression in OLGs, especially those expressing the FTDP-17 human P301L mutant tau. Notably, structural disruption of myelin and axons preceded the emergence of thioflavin-S positive tau inclusions in OLGs, but impairments in axonal transport occurred even earlier, whereas motor deficits developed subsequently, especially in Tg mice with the highest tau expression levels. These data suggest that the accumulation of tau in OLG cause neurodegeneration, and we infer they do so by disrupting axonal transport. We suggest that similar defects may also occur in sporadic and hereditary human tauopathies with OLG tau pathologies.

Enhanced neurofibrillary tangle formation, cerebral atrophy, and cognitive deficits induced by repetitive mild brain injury in a transgenic tauopathy mouse model

Traumatic brain injury (TBI) is a risk factors for Alzheimer's disease (AD), and repetitive TBI (rTBI) may culminate in dementia pugilistica (DP), a syndrome characterized by progressive dementia, parkinsonism, and the hallmark brain lesions of AD, including neurofibrillary tangles (NFTs), formed by abnormal tau filaments and senile plaques (SPs) composed of Abeta fibrils. Previous study showed that mild rTBI (mrTBI) accelerated the deposition of Abeta in the brains of transgenic (Tg) mice (Tg2576) that over-express human Abeta precursor proteins with the familial AD Swedish mutations (APP695swe) and model of AD-like amyloidosis. Here, we report studies of the effects of mrTBI on AD-like tau pathologies in Tg mice expressing the shortest human tau isoform (T44) subjected to mrTBI, causing brain concussion without structural brain damage to simulate injuries linked to DP. Twelve-month-old Tg T44 (n = 18) and wild-type (WT; n = 24) mice were subjected to mrTBI (four times a day, 1 day per week, for 4 weeks; n = 24) or sham treatment (n = 18). Histopathological analysis of mice at 9 months after mrTBI revealed that one of the Tg T44 mice showed extensive telencephalic NFT and cerebral atrophy. Although statistical analysis of neurobehavioral tests at 6 months after mrTBI did not show any significant difference in any of groups of mice, the Tg T44 mouse with extensive NFT had an exceptionally low neurobehavioral score. The reasons for the augmentation of tau pathologies in only one T44 tau Tg mouse subjected to mrTBI remain to be elucidated.

Long-term treatment of generalised myasthenia gravis with FK506 (tacrolimus)

Efficacy and safety of long term use of FK506 (2-4.5 mg/day) for a maximum of two years were evaluated in 12 patients with generalised myasthenia gravis (MG). At the end of the study, eight patients (67%) showed improvement in either MG score or Activities in Daily Living score, and prednisolone dosage could be reduced in seven patients (58%), with a mean reduction ratio of 37%. Long term use of FK506 for MG can be more effective than short term administration, with no serious side effects.

Retarded axonal transport of R406W mutant tau in transgenic mice with a neurodegenerative tauopathy

Intracellular accumulations of filamentous tau inclusions are neuropathological hallmarks of neurodegenerative diseases known as tauopathies. The discovery of multiple pathogenic tau gene mutations in many kindreds with familial frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17) unequivocally confirmed the central role of tau abnormalities in the etiology of neurodegenerative disorders. To examine the effects of tau gene mutations and the role of tau abnormalities in neurodegenerative tauopathies, transgenic (Tg) mice were engineered to express the longest human tau isoform (T40) with or without the R406W mutation (RW and hWT Tg mice, respectively) that is pathogenic for FTDP-17 in several kindreds. RW but not hWT tau Tg mice developed an age-dependent accumulation of insoluble filamentous tau aggregates in neuronal perikarya of the cerebral cortex, hippocampus, cerebellum, and spinal cord. Significantly, CNS axons in RW mice contained reduced levels of tau when compared with hWT mice, and this was linked to retarded axonal transport and increased accumulation of an insoluble pool of RW but not hWT tau. Furthermore, RW but not hWT mice demonstrated neurodegeneration and a reduced lifespan. These data indicate that the R406W mutation causes reduced binding of this mutant tau to microtubules, resulting in slower axonal transport. This altered tau function caused by the RW mutation leads to increased accumulation and reduced solubility of RW tau in an age-dependent manner, culminating in the formation of filamentous intraneuronal tau aggregates similar to that observed in tauopathy patients.

Low-dose tacrolimus treatment in thymectomised and steroid-dependent myasthenia gravis

OBJECTIVES

The effects of tacrolimus, a new immunosuppressive drug, which inhibits calcineurin pathway and also might enhance corticosteroid (CS) receptor-mediated gene expressions, on clinical outcome and biochemical data were evaluated in thymectomised and steroid-dependent myasthenia gravis (MG) patients.

PATIENTS AND METHODS

We administrated low-dose tacrolimus (3 mg/day orally) to 17 steroid-dependent thymectomised MG patients. They were followed for 4 to 58 months, average 19.2 months. The MG activities of daily living (MGADL) scores and the dosage of prednisolone (PSL) were assessed at baseline and 4 months later.

RESULTS

The average MGADL scores improved from 6.8 to 5.0 (p < 0.01) at 4 months; to 3.5 at the last visit (p < 0.01) as well as the average dosage of PSL reducing from 31.6 to 24.1 mg/alternate day (p < 0.01) at 4 months; 14.6 mg at the last visit (p < 0.01).

CONCLUSIONS

The additional low dose tacrolimus therapy for steroid-dependent thymectomised MG is effective in improving symptoms as well as allowing the tapering of CSs.

Increased ability of peripheral blood lymphocytes to degrade laminin in multiple sclerosis

T lymphocytes and macrophages probably play a role in the pathogenesis of multiple sclerosis (MS), and migration of these cells into the central nervous system is facilitated by disruption of the capillary basement membrane. Laminin is a major extracellular matrix of the basement membrane. To investigate whether ability of lymphocytes to degrade laminin correlates with disease activity in MS, we conducted a prospective study in consecutive 24 MS patients. A novel quantitative assay was developed to estimate the ability of peripheral blood mononuclear cells (PBMCs) to degrade laminin. The assay was performed every four weeks over a period of 12 months. During the study period, a total of 41 relapses were observed. The ability to degrade laminin was significantly higher in MS patients, even during clinical remission, than in normal and neurological controls, and was transiently increased further within 4 weeks before relapse (p=0.076). In MS, the ability of peripheral blood lymphocytes to degrade laminin increases, and may correlate with disease activity.

Clinical study of FK506 in patients with myasthenia gravis

To investigate the usefulness of low-dose FK506 for the treatment of myasthenia gravis (MG), we treated 19 patients with generalized MG in a 16-week open clinical trial of FK506 (3-5 mg/day). At the end of the trial, total MG scores (range: 0-27 points) improved by 3 points or more in 7 of 19 patients (37%), and activities of daily living (ADL) scores (range: 0-6 points) also improved by 1 point or more in 8 of 19 patients (42%). Nine of 19 patients (47%) showed improvement in either MG or ADL scores. Significant reduction of anti-acetylcholine receptor antibody titers and interleukin 2 production were observed at the end of this study. Minor but commonly observed side effects were an increase in neutrophil count and a decrease in lymphocyte count. No serious adverse events such as renal toxicity or diabetes mellitus were observed during the 16-week treatment period. FK506 could safely serve as an adjunct to steroid therapy for MG at low dosage.

Reduction of detyrosinated microtubules and Golgi fragmentation are linked to tau-induced degeneration in astrocytes

Several human neurodegenerative diseases are associated with abnormal accumulations of aggregated tau proteins and glial degeneration in astrocytes, but the mechanism whereby tau proteins cause astrocytic degeneration is unclear. Here, we analyzed the biological consequences of overexpressing the longest human tau isoform in primary cultures of rat astrocytes using adenoviral-mediated gene transfer. Significantly, we found specific decreases in stable detyrosinated [glutamate (Glu)] microtubules (MTs) with concomitant increases in tubulin biosynthesis and the accumulation of acetylated, tyrosinated, alpha- and beta-tubulin. The consequences of this selective reduction in stable Glu-MTs included contemporaneous decreases in kinesin levels, collapse of the intermediate filament network, progressive disruption of kinesin-dependent trafficking of organelles, fragmentation of the Golgi apparatus that culminated in atrophy, and non-apoptotic death of astrocytes. These results suggest that reduced stable Glu-MTs is a primary consequence of tau accumulation that initiates mechanisms underlying astrocyte dysfunction and death in human neurodegenerative glial tauopathies.

Amyotrophic lateral sclerosis/parkinsonism dementia complex: transgenic mice provide insights into mechanisms underlying a common tauopathy in an ethnic minority on Guam

Intracytoplasmic filamentous tau inclusions are neuropathological hallmarks of amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) of Guam and the defining lesions of other neurodegenerative disorders known as tauopathies. Here we review current insights into the cell and molecular neuropathology of ALS/PDC, a common tauopathy in the Chamorro population on Guam. We also summarize recent advances in understanding this disorder through studies of transgenic (Tg) mouse models of this tauopathy. Briefly, overexpression of human tau isoforms in the central nervous system of Tg mice resulted in a neurodegenerative tauopathy with a phenotype similar to ALS/PDC. Specifically, argyrophilic, congophilic, and tau immunoreactive inclusions accumulated with age in cortical and brainstem neurons of these mice, but they were most abundant in spinal cord neurons, and the inclusions contained 10- to 20-nm tau-positive straight filaments. There also was extensive gliosis in spinal cord associated with axonal degeneration in the ventral roots, while remaining axons in spinal nerves showed a loss of microtubules and reduced fast axonal transport. With advancing age, these Tg mice showed increasing motor weakness, and this was accompanied by a progressive increase in the phosphorylation and insolubility of brain and spinal cord tau proteins. Thus, tau Tg mice recapitulate key phenotypic features of ALS/PDC neuropathology in an ethnic minority on Guam, and these animal models provide new opportunities to discover novel therapies for this and related tauopathies.

Expression of nitric oxide synthases in the anterior horn cells of amyotrophic lateral sclerosis

The authors investigated for a correlation between the expression of nitric oxide synthases (NOSs) with the severity of motor neuronal loss in the anterior horns of patients with amyotrophic lateral sclerosis (ALS). Spinal cords from six patients with ALS and from three normal controls were examined. The sections of cervical, lumbar, and sacral cord including Onuf's nucleus, which are seldom degenerated until the late stage, were stained with three antibodies against NOSs (anti-n-NOS, anti-e-NOS, and anti-i-NOS) using ABC methods. Perikarya of motor neurons in ALS, but not in controls, were immunoreactive against anti-n-NOS and e-NOS. Anti-i-NOS did not recognize the motor neurons of ALS or of controls. The immunoreactivity for n- and e-NOSs was approximately the same in the sections of cervical, lumbar, and sacral cord in ALS. No significant differences in immunoreactivity were observed among the patients with ALS. These results suggest that the expression of NOSs does not immediately affect neuronal loss in ALS.

The effect of fosfomycin on glycopeptide antibiotic-induced nephrotoxicity in rats

The effect of coadministration of fosfomycin (FOM) on glycopeptide antibiotic-induced nephrotoxicity for 3 days was investigated in rats. To induce nephrotoxicity in a short time, gentamicin (GM) was also coadministered. In the present study, FOM decreased glycopeptide antibiotic-induced nephrotoxicity as shown by reduced urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) as well as fewer histopathological signs of nephrotoxicity in the groups treated with the combination of glycopeptide and FOM as compared with a glycopeptide alone. In addition, the higher the dose of FOM, the more it decreased urinary NAG levels, suggesting that the role of FOM in alleviating nephrotoxicity is dose dependent. The accumulation of teicoplanin and vancomycin was significantly lower in the renal cortex of rats treated with the combination of glycopeptide antibiotics and FOM as compared with glycopeptide antibiotics alone (P < 0.05). In conclusion, the concomitant administration of FOM and glycopeptide antibiotics may help to achieve a chemotherapeutic strategy that reduces the nephrotoxic effects of glycopeptide antibiotics.

Frontotemporal dementia and tauopathy

The presence of abundant neurofibrillary lesions made of hyperphosphorylated tau proteins is the characteristic neuropathology of a subset of neurodegenerative disorders classified as "tauopathies." The discovery of mutations in the tau gene in frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) constitutes convincing evidence that tau proteins play a key role in the pathogenesis of neurodegenerative disorders. Moreover, it now is known that the most common form of sporadic frontotemporal dementia (FTD), which is characterized by frontotemporal neuron loss, gliosis, and microvacuolar change, also is a tauopathy caused by a loss of tau protein expression. Thus, these discoveries have begun to change the classification and the neuropathologic diagnosis of FTD and tauopathies, as well as current understanding of the disease mechanisms underlying them. Although transgenic mice expressing wild-type human tau or variants thereof with an FTDP-17 mutation result in tau pathologies and brain degeneration similar to that seen in human tauopathies, the precise mechanisms leading to the onset and progression of neurodegenerative disorders remain incompletely understood. Here, we review current understanding of human neurodegenerative tauopathies and prospects for translative recent insights about these into therapeutic interventions to prevent or ameliorate them.

Enhanced expression of I-kappaB with neurofibrillary pathology in Alzheimer's disease

Inflammatory and immune responses are known to be involved in the pathogenesis of Alzheimer's disease (AD). NF-kappaB is a major transcription factor that plays a central role in the inflammatory and immune responses and is regulated by I-kappaB through an autoregulatory feedback system. Southwestern immunohistochemistry and immunohistochemistry in our study demonstrated activated NF-kappaB in AD brains. However, there was also activated expression of I-kappaB in a distribution that corresponded to the neurofibrillary pathology of AD. These observations indicate that disruption of the autoregulatory mechanism of NF-kappaB in brain regions with neurofibrillary pathology may play a role in the pathogenesis of AD.

Attenuated neurodegenerative disease phenotype in tau transgenic mouse lacking neurofilaments

Previous studies have shown that transgenic (Tg) mice overexpressing human tau protein develop filamentous tau aggregates in the CNS. The most abundant tau aggregates are found in spinal cord and brainstem in which they colocalize with neurofilaments (NFs) as spheroids in axons. To elucidate the role of NF subunit proteins in tau aggregate formation and to test the hypothesis that NFs are pathological chaperones in the formation of intraneuronal tau inclusions, we crossbred previously described tau (T44) Tg mice overexpressing the smallest human tau isoform with knock-out mice devoid of NFL (NFL-/-) or NFH (NFH-/-). Depletion of NF subunit proteins from the T44 mice (i.e., T44;NFL-/- and T44;NFH-/-), in particular NFL, resulted in a dramatic decrease in the total number of tau-positive spheroids in spinal cord and brainstem. Concomitant with the reduction in spheroid number, the bigenic mice showed delayed accumulation of insoluble tau protein in the CNS, increased viability, reduced weight loss, and improved behavioral phenotype when compared with the single T44 Tg mice. These results imply that NFs are pathological chaperones in the development of tau spheroids and suggest a role for NFs in the pathogenesis of neurofibrillary tau lesions in neurodegenerative disorders that contain both NFs and tau proteins.

Influence of the light schedule on the toxic interaction between propranolol and disopyramide in chick embryos

The effect of the light schedule on toxic interactions between propranolol and disopyramide were studied in chick embryos. Fertilized eggs of White Leghorns were incubated under dark conditions and investigated, on two occasions, under light conditions or under dark conditions. Propranolol, with and without disopyramide, was injected into the air sac of fertilized eggs on the 16th day of incubation. Electrocardiograms (ECGs) were recorded 0 to 60 min after the injection. After the injection of propranolol with disopyramide, the heart rate was significantly decreased compared with the injection of propranolol alone under light conditions. In addition, this toxic interaction between propranolol and disopyramide was more severe under dark conditions than under light conditions. These findings indicate that manipulation of the light schedule has a marked influence on the toxic interaction between propranolol and disopyramide in chick embryos.

Serum levels of tumor necrosis factor-alpha in chronic inflammatory demyelinating polyneuropathy

BACKGROUND

Activated macrophages and T lymphocytes may play a role in the pathogenesis of chronic inflammatory demyelinating polyneuropathy (CIDP). Both cell types secrete tumor necrosis factor-alpha (TNFalpha), which has toxic effects on myelin and endothelial cells.

METHODS

The serum concentration of TNFalpha was measured by ELISA and compared with clinical and electrophysiological profiles in 20 patients with CIDP.

RESULTS

An increased serum level of TNFalpha was detected in 5 (25%) patients and was associated with subacute progression, severe neurologic disabilities, and symmetric weakness involving proximal as well as distal muscles. TNFalpha levels increased during the active phase in this subgroup of patients. The levels of TNFalpha correlated with the severity of demyelinating conduction abnormalities in the intermediate as well as distal nerve segments, suggesting demyelination diffusely distributed along the nerves.

CONCLUSION

Circulating TNFalpha increases during the active phase in a subgroup of CIDP patients and may play a role in the pathogenesis of demyelination and the breakdown of the blood-nerve barrier in CIDP.

Expression of matrix metalloproteinase-9 and urinary-type plasminogen activator in Alzheimer's disease brain

OBJECTIVE

Urinary-type plasminogen activator (uPA) binding to uPA receptor (uPAR) promotes the activation of matrix metalloproteinase-9 (MMP-9), which degrades amyloid beta protein (Abeta) in vitro. We investigated the expression of MMP-9, uPA, and uPAR in post-mortem brains from patients with Alzheimer's disease (AD) and those with vascular dementia (VD).

MATERIAL AND METHODS

We used immunohistochemistry to examine the sections of the parietal lobe and hippocampus from 4 AD and 3 VD patients. The anti-MMP-9 antibody, anti-uPA antibody, and anti-uPAR antibody were used to perform immunohistological analysis.

RESULTS

In the brain tissues from the AD patients, we found expression of MMP-9 in the cytoplasm of neurons, neurofibrillary tangles, senile plaques, vascular walls and uPAR expression in the cytoplasm of neurons and vascular walls. uPA was detected only in the vascular walls. On the other hand, we could not find expression of MMP-9, uPAR and uPA in the brain tissues of the VD patients, except for the vascular walls.

CONCLUSION

The neurons in the AD brains expressed MMP-9 and uPAR. MMP-9 may be produced for the degradation of Abeta, but uPA, which activates MMP-9, was not immunolocalized to the neurons in the AD brains.

Age-dependent induction of congophilic neurofibrillary tau inclusions in tau transgenic mice

Intraneuronal filamentous tau inclusions such as neurofibrillary tangles (NFTs) are neuropathological hallmarks of Alzheimer's disease (AD) and related sporadic and familial tauopathies. NFTs identical to those found in AD brains have also been detected in the hippocampus and entorhinal cortex of cognitively normal individuals as they age. To recapitulate age-induced NFT formation in a mouse model, we examined 12- to 24-month-old transgenic (Tg) mice overexpressing the smallest human brain tau isoform. These Tg mice develop congophilic tau inclusions in several brain regions including the hippocampus, amygdala, and entorhinal cortex. NFT-like inclusions were first detected in Tg mice at 18 to 20 months of age and they were detected by histochemical dyes that bind specifically to crossed beta-pleated sheet structures (eg, Congo red, Thioflavin S). Moreover, ultrastructurally these lesions contained straight tau filaments comprised of both mouse and human tau proteins but not other cytoskeletal proteins (eg, neurofilaments, microtubules). Isolated tau filaments were also recovered from detergent-insoluble tau fractions and insoluble tau proteins accumulated in brain in an age-dependent manner. Thus, overexpression of the smallest human brain tau isoform resulted in late onset and age-dependent formation of congophilic tau inclusions with properties similar to those in the tangles of human tauopathies, thereby implicating aging in the pathogenesis of fibrous tau inclusions.

Nephrotoxicity of teicoplanin in rats

Teicoplanin, a glycopeptide antibiotic, is marketed in a number of European countries and has recently been put on the market in Japan. The spectrum of antibacterial activity of teicoplanin is equivalent or superior to that of vancomycin. The aim of the present study is to examine the nephrotoxicity of teicoplanin compared with vancomycin in rats. Wistar male rats, housed in a light-controlled room at room temperature for 1 week, were used. They were injected with either 15 or 50 mg/kg/day of teicoplanin or 50 or 200 mg/kg/day of vancomycin at 13:00 daily for 14 days. The rats were randomly assigned to groups of five rats each and were housed individually in metabolic cages to collect urine. Urine samples were collected 24 hours prior to the drug treatment and every 24 hours thereafter for 14 days. N-Acetyl-beta-D-glucosaminidase (NAG) activity was determined in the supernatant and expressed in international units per total urine collected for 24 hours. The group which was given vancomycin 200 mg/kg/day had significantly elevated urinary NAG levels compared with the other groups (p < 0.05). No significant differences were observed in the NAG levels in urine among the remaining three groups. These results suggest that the nephrotoxicity of teicoplanin may be only one-fourth that of vancomycin in rats. It appears that by extrapolating the dose amount required for the treatment in humans to rats, the high dose of teicoplanin was set at 50 mg/kg/day and that of vancomycin, 200 mg/kg/day. The recommended dose for teicoplanin will probably be 200 mg/day compared to 2 g/day of vancomycin. If the teicoplanin dose is only one-tenth that of the vancomycin dose, then teicoplanin should be better tolerated than vancomycin in terms of nephrotoxicity.

Expression of invariant chain and pro-cathepsin L in Alzheimer's brain

Inflammatory and immune systems are involved in the pathogenesis of Alzheimer's disease (AD), but those systems in the human brain have not been well identified. Cathepsin L might play a predominant role in the degradation of the invariant chain (Ii), which plays a critical role in antigen presentation to block the antigen-binding site of the major histocompatibility complex class II. We examined the expression of Ii and pro-cathepsin L (pCPL) in AD and normal brains by using immunohistochemistry. Ii expresses only in resting or mildly activated microglia, whereas pCPL strongly expresses in fully activated microglia but not in resting or mildly activated microglia in AD. Normal brain tissues have rarely been stained for Ii or pCPL. These results suggest that the activation of microglia leads to expression of a complex of Ii and human leukocyte antigen class II at first, and that further activation, which is followed by cluster formation and enlargement of microglia frequently seen in the AD brain, might cause pCPL expression to degrade Ii. Our study confirmed that microglia plays a central role in the immune system of the brain, and that an activation of microglia is involved in the pathogenesis of AD.

[Beneficial effects of CHOP therapy in a case of intravascular large B-cell lymphoma diagnosed by skin biopsy]

We report a case of intravascular large B-cell lymphoma. A 52-year-old man gradually developed dementia and abnormal behaviors, which were later accompanied by spastic paraplegia and sensory disturbance in his lower limbs. MR imaging of his brain showed high signal intensity lesions on T2 imaging. IMP-SPECT images of the brain showed diffuse reduction of radioisotope uptake. Many skin rashes that looked like senile hemangioma were observed on his body. Several of those were biopsied, and the diagnosis of intravascular large B-cell lymphoma was made because of malignant B lymphocytes filling the vessel lumens in one of the seven biopsy specimens. CHOP therapy was performed and found to be effective for the neurological disorders such as dementia, paraplegia, and sensory disturbance. Our case suggests that skin biopsy for more than one sample of the skin rashes is very important for the diagnosis of intravascular large B-cell lymphoma. CHOP therapy might be effective in this case because of early diagnosis by skin biopsy.

Selective distribution of matrix metalloproteinase-3 (MMP-3) in Alzheimer's disease brain

A growing amount of evidence indicates that matrix metalloproteinases (MMPs) may play an important role in the pathogenesis of Alzheimer's disease (AD). Stromelysin-1 (MMP-3) plays a central role in activating latent-type MMPs, which are originally secreted as proenzymes. We examined MMP-3 immunoreactivity in the brains of patients who had suffered from Alzheimer's disease and in those of neurologically normal persons. The interstitium between myelinated axons and astrocytes in the white matter of all brain tissues, and senile plaques in the gray matter of the patients with AD were stained with a monoclonal antibody to MMP-3. Comparison of the number of senile plaques stained with the antibody against MMP-3 in the parietal cortex with that in the hippocampus showed that fewer plaques were stained in the hippocampus. The selective distribution of MMP-3 in the human brain suggests that MMP-3 might play an important role in the pathogenesis of AD, especially in the degradation of beta-amyloid protein.

The dropped head sign in parkinsonism

We describe seven patients who exhibited the dropped head sign in parkinsonism. These included six females and one male between the ages of 53 and 74. Three patients were clinically diagnosed as probable Parkinson's disease and four were diagnosed with probable multiple system atrophy. None had weakness in the posterior neck muscles or spasms in the anterior neck muscles. When the patients attempted to extend the head voluntarily or passively muscle contraction that was not seen in the dropped-head condition appeared. Surface electromyography of the neck indicated that the anterior neck muscles had rigidity. A gamma-block of the SCM muscles reduced the muscle activity when the head was elevated and improved the dropped-head condition slightly. These findings seem to indicate that the dropped head sign in parkinsonism could be associated with anterior neck muscle rigidity. Although the severity of the dropped head condition was affected by medication or by the clinical course in three patients, there was no clear relationship between the severity of the dropped head condition and the parkinsonism. We suspected that unbalanced muscle rigidity between the anterior and the posterior neck muscles could cause the dropped head sign.

Expression of the membrane-type 3 matrix metalloproteinase (MT3-MMP) in human brain tissues

Membrane-type 3 matrix metalloproteinase (MT3-MMP) is a novel MT-MMP which has a transmembrane domain at the C terminus, and mediates activation of pro-gelatinase A, just as does MT1-MMP. Previously, we reported that MT1-MMP was expressed on microglial cells only in the white matter [Yamada T, Yoshiyama Y, Sato H, Seiki M, Shinagawa A, Takahashi M (1995) Acta Neuropathol 90:421-424]. In the present study of both non-neurological and Alzheimer brain tissues, we examined the localization of MT3-MMP by immunohistochemistry. Anti-MT3-MMP antibodies gave positive staining of microglial cells in all brain tissues. Positively stained microglia were found not only in the white matter but also in the gray matter. Reverse transcriptase-polymerase chain reaction for MT3-MMP mRNA showed the same amount of expression in gray and white matters, while that for gelatinase A and MT1-MMP mRNA expressed much higher in the white matter than in the gray matter. These results suggest that MT3-MMP may play a role on microglial cells, although its role may be different from MT1-MMP in the brain.

Expression of adult T cell leukemia-derived factor in human brain and peripheral nerve tissues

In both nonneurological and Alzheimer brains, we examined the localization of adult T cell leukemia-derived factor (ADF) by immunohistochemistry, that of its mRNA by in situ hybridization, and its semiquantitative mRNA analyses by RT-PCR. Anti-ADF antibody gave positive staining of white matter astrocytes and Schwann cells in the posterior root. Their intense and abundant staining was seen in Alzheimer brains. In situ hybridization for ADF mRNA showed identical signals in the white matter astrocytes. The evidence was also confirmed by RT-PCR analysis. These results suggest that redox regulation may play a role in Alzheimer pathology.

Protective effect of ceftriaxone against the nephrotoxicity of isepamicin administered once daily in rats

The protective effect of ceftriaxone on isepamicin-induced nephrotoxicity was investigated. For 14 d, Wistar rats were administered either ceftriaxone 100 mg/kg intraperitoneally, isepamicin 300 mg/kg subcutaneously, or ceftriaxone isepamicin in combination. The animals given 300 mg/kg of isepamicin showed a significant increase in urine NAG (N-acetyl-beta-D-glucosaminidase) levels as compared with the control animals which received saline (p<0.01). However, the increase in NAG level was markedly less when isepamicin was administered in combination with ceftriaxone (p<0.01). Ceftriaxone alone had no effect on urine NAG activity. Serum creatinine levels were significantly higher in animals treated with isepamicin alone than in control animals (p<0.01) or animals receiving the isepamicin ceftriaxone combination (p<0.01). After 14 d of treatment, ceftriaxone had not accumulated in renal tissue, but it did reduce the renal intracortical accumulation of isepamicin (p<0.01). Histopathologically, ceftriaxone induced very few cellular alterations and considerably reduced the manifestation of typical signs of isepamicin nephrotoxicity. This investigation demonstrates that ceftriaxone protects animals against isepamicin-induced nephrotoxicity.

Possible roles of transglutaminases in Alzheimer's disease

The localizations of two transglutaminases [factor XIIIa and tissue transglutaminase (tTG)] and their mRNAs were examined in human brain tissues from neurologically normal and Alzheimer disease (AD) cases, using immunohistochemical and in situ hybridization methods. In all cases, meningeal macrophages and ependymal macrophage/microglia were positive for factor XIIIa. The mRNA encoding factor XIIIa was detected in macrophages and microglia. As reported previously, intense staining with the antibody to factor XIIIa of a subset of microglia was seen in the parietal cortex in AD brains. Few or no microglia were found associated with classical senile plaques. In contrast, many labeled microglia were associated with primitive plaques. Further-more, most of these cells were mainly seen in the subpial cortical layer but were very rare in the hippocampus. On the other hand, few factor-XIIIa-positive microglia were found in the parietal cortices from non-neurological cases, but moderate numbers were found in their hippocampal tissues. TG and its mRNA were localized in astrocytes in all the cases. In AD, a few neurofibrillary tangles were positive to tTG. These results suggest that the subsets of microglia which express factor XIIIa may play some roles in the early phase of AD pathology.