Hanna Rosenmann

Efficacy and safety of immunization with phosphorylated tau against neurofibrillary tangles in mice

As an abnormally folded and aggregated protein, tau composed of neurofibrillary tangles (NFTs) in Alzheimers disease and other tauopathies seems to be a candidate for immunotherapy. Yet, the encephalitogenicity of full-length tau protein, recently reported by us in immunized mice, demands to carefully and selectively target pathological tau and address both efficacy (anti-NFT effect) and safety (free of encephalitis). We immunized NFT mice with NFT-related phosphorylated (phos) tau peptides, using an immunization protocol aimed to predispose a proinflammatory milieu in CNS as a set up to detect biohazard, an approach we used when the neurotoxicity of full-length tau was detected [use of complete Freund adjuvant (CFA) with pertussis toxin (PT)]. A decrease of about 40% in NFT burden in CNS was demonstrated and was accompanied with an increase in microglial burden. Anti-phos-tau antibodies were detected in serum and blood vessels in the CNS, while no encephalitogenicity (free of clinical neurological deficits, of adverse effects on brain inflammatory cells and of axonal damage) was recorded. The level of the lysosomal proteases, cathepsins D and L, was affected in the immunized mice suggesting the possible involvement of the lysosomal system in the decrease of NFTs. The robust anti-NFT effect and the lack of encephalitogenicity in NFT mice immunized with phos-tau peptides, even though CFA with PT was included in vaccine, point to their anti-NFT therapeutic potential.

Splicing mutation in dysferlin produces limb-girdle muscular dystrophy with inflammation.

Mutations in dysferlin were recently described in patients with Miyoshi myopathy, a disorder that preferentially affects the distal musculature, and in patients with Limb-Girdle Muscular Dystrophy 2B, a disorder that affects the proximal musculature. Despite the phenotypic differences, the types of mutations associated with Miyoshi myopathy and Limb-Girdle Muscular Dystrophy 2B do not differ significantly. Thus, the etiology of the phenotypic variability associated with dysferlin mutations remains unknown. Using genetic linkage and mutation analysis, we identified a large inbred pedigree of Yemenite Jewish descent with limb-girdle muscular dystrophy. The phenotype in these patients included slowly progressive, proximal, and distal muscular weakness in the lower limbs with markedly elevated serum creatine kinase (CK) levels. These patients had normal development and muscle strength and function in early life. Muscle biopsies from 4 affected patients showed a typical dystrophic pattern but interestingly, in 2, an inflammatory process was seen. The inflammatory infiltrates included primarily CD3 positive lymphocytes. Associated with this phenotype, we identified a previously undescribed frameshift mutation at nucleotide 5711 of dysferlin. This mutation produced an absence of normal dysferlin mRNA synthesis by affecting an acceptor site and cryptic splicing. Thus, splice site mutations that disrupt dysferlin may produce a phenotype associated with inflammation.

Statins reduce the neurofibrillary tangle burden in a mouse model of tauopathy.

Abstract Statin treatment has been associated with a reduced risk of Alzheimer disease and decreased amyloid deposition in mouse models. No animal studies have reported effects of statins on tau aggregates and neurofibrillary tangles (NFTs), the pathological hallmarks of Alzheimer disease that correlate with dementia. We investigated the effect of statins on NFTs in a transgenic mouse tauopathy model and found the following: 1) 1-month treatment with the blood-brain barrier-permeable agent simvastatin in normocholesterolemic aged mice significantly reduced the NFT burden and decreased lectin-positive microglia; 2) simvastatin significantly decreased NFTs and improved T-maze performance in young animals treated for 8 months; 3) treatment of hypercholesterolemic mice for 5 months with blood-brain barrier-impermeable atorvastatin markedly reduced the NFT burden and decreased lectin-positive microglia; 4) nonstatin cholesterol-lowering strategies showed a modest NFT decrease compared with statin treatment; and 5) there was a positive correlation between microglial and NFT burden (r = 0.8). Together, these results suggest that statins reduce NFT burden irrespective of blood-brain barrier permeability at both early and late ages in long- and short-term treatment paradigms and under normocholesterolemic and hypercholesterolemic conditions. The decrease in microglia, coupled with the limited effect of nonstatin cholesterol lowering, suggests that the anti-NFT effect of statins may be related to their anti-inflammatory and not necessarily to their cholesterol-lowering properties. Statins may provide therapy against NFTs in tauopathies, particularly when NFTs are the major neuropathologic component.

Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings.

Adult polyglucosan body disease (APBD) is an autosomal recessive leukodystrophy characterized by neurogenic bladder, progressive spastic gait, and peripheral neuropathy. Polyglucosan bodies accumulate in the central and peripheral nervous systems and are often associated with glycogen branching enzyme (GBE) deficiency. To improve clinical diagnosis and enable future evaluation of therapeutic strategies, we conducted a multinational study of the natural history and imaging features of APBD.

Detection of circulating antibodies against tau protein in its unphosphorylated and in its neurofibrillary tangles-related phosphorylated state in Alzheimer's disease and healthy subjects.

While the presence of naturally occurring antibodies (Abs) against amyloid-beta in AD patients and healthy subjects have been repeatedly reported, no data on the presence of naturally occurring Abs against tau protein, in its unphosphorylated as well as its pathologically phosphorylated state, has been reported so far. We describe here the detection of circulating Abs against unphosphorylated and pathologically phosphorylated tau protein in sera of 17 aged subjects: nine Alzheimers disease (AD) patients and eight healthy individuals. An ongoing autoimmune process may take place, as is suggested by the presence of both IgM class anti-tau Abs, as well as IgG. A preliminary evidence for higher anti-phosphorylated-tau Abs of IgM class in AD patients relative to controls is indicated, but demands further confirmation in a larger sample. Detection of naturally occurring anti-tau antibodies may point to the possibility that some autoimmune process may take place against the tau neuronal protein, including its pathologically phosphorylated state which compose the neurofibrillary tangles. Whether these Abs are neuroprotective or neurotoxic - is unknown, as it is with anti-amyloid-beta Abs.

Detection of 14-3-3 protein in the CSF of genetic Creutzfeldt-Jakob disease

The 14-3-3 protein, a protein involved in signal transduction, is present in the CSF of patients with Creutzfeldt-Jakob disease (CJD) and not in patients with other dementing diseases. We show here that this is also true for patients with E200K CJD, but not for healthy carriers of the mutation.

Repeated immunization of mice with phosphorylated-tau peptides causes neuroinflammation ☆

The recent studies of others and of us showing robust efficacy of anti-tangle immunotherapy, directed against phosphorylated (phos)-tau protein, may pave the way to clinical trials of phos-tau immunotherapy in Alzheimers-disease and other tauopathies. At this stage addressing the safety of the phos-tau-immunotherapy is highly needed, particularly since we have previously shown the neurotoxic potential of tau-immunotherapy, specifically of full-length unphosphorylated-tau vaccine under a CNS-proinflammatory milieu [induced by emulsification in complete-Freunds-adjuvant (CFA) and pertussis-toxin (PT)] in young wild-type (WT)-mice. The aim of our current study was to address safety aspects of the phos-tau-immunotherapy in both neurofibrillary-tangle (NFT)-mice as well as in WT-mice, under challenging conditions of repeated immunizations with phos-tau peptides under a CNS-proinflammatory milieu. NFT- and WT-mice were repeatedly immunized (7 injections in adult-, 4 in aged-mice) with phos-tau peptides emulsified in CFA-PT. A paralytic disease was evident in the phos-tau-immunized adult NFT-mice, developing progressively to 26.7% with the number of injections. Interestingly, the WT-mice were even more prone to develop neuroinflammation following phos-tau immunization, affecting 75% of the immunized mice. Aged mice were less prone to neuroinflammatory manifestations. Anti-phos-tau antibodies, detected in the serum of immunized mice, partially correlated with the neuroinflammation in WT-mice. This points that repeated phos-tau immunizations in the frame of a proinflammatory milieu may be encephalitogenic to tangle-mice, and more robustly to WT-mice, indicating that - under certain conditions - the safety of phos-tau immunotherapy is questionable.

CSF Biomarkers for Amyloid and Tau Pathology in Alzheimer's Disease

Reliable biomarkers for Alzheimers disease (AD) are highly needed in the clinic. As a fluid surrounding the brain and reflecting the major neuropathological features characteristic to the AD brain, the cerebrospinal fluid (CSF) provides the natural source for AD biomarkers. The expected use of an ideal AD biomarker is for the following purposes: (1) diagnosis, (2) prediction, (3) monitoring of disease progression, and (4) drug discovery. Review of the literature revealed that CSF analysis, specifically amyloid-beta (Aβ42, total (T)-tau, and phosphorylated (P)-tau, are reliable markers for AD diagnosis, even at very early stages, particularly vs. healthy controls, while more limited evidence for distinguishing from other dementias. As for prediction, abnormal CSF markers are predictors of cognitive decline in healthy subjects, converting from MCI to development of AD, and of the rate of cognitive decline in mild AD. Regarding monitoring disease progression, the use of CSF biomarkers does not seem very promising since a comparison of the marker levels between baseline and following years of follow-up revealed a remarkable stability of biomarker levels in CSF. As for the use in drug discovery, it is estimated that using CSF markers for the selection of subjects for clinical trials may reduce robustly sample size and trial costs. Yet, since no effective drug is currently available, the contribution of CSF AD biomarkers in drug discovery cannot be currently fully assessed. Nevertheless, testing CSF for evidence of CNS inflammation may help safety monitoring in AD clinical trials. Factors affecting CSF biomarker levels that should be taken into account are assay variability as well as effects of age, gender, apoE and other genetic variations, education, and time of day. Much effort has been and is still being dedicated into developing and validating CSF AD biomarkers by many centers in the world. Identifying additional CSF components, reflecting not only the lesions characteristic to AD (plaques and tangles) but also more functional and structural brain parameters, may provide a wider profile of the changes taking place in AD brains, and be further used as reliable CSF biomarkers for AD monitoring.

Frontotemporal dementia and parkinsonism with the P301S tau gene mutation in a Jewish family

Abstract.Background: Frontotemporal dementia with parkinsonism linked to chromosome 17q21–22 (FTDP-17) is an autosomal dominant tauopathy manifested by a variable combination of personality changes, cognitive decline and hypokinetic-rigid movement disorder. Significant clinical and pathological heterogeneity of FTDP-17 is related in part to more than 20 different pathogenic mutations identified in the tau gene. Among others, the P301S mutation has been previously reported in three families of European and one of Japanese origin presenting with different clinical phenotypes. Objectives To report a three-generation family of Jewish-Algerian origin with FTDP-17 due to the P301S tau mutation. Methods: Clinical, neuropsychological and neuroimaging evaluation of 3 patients, tau genotyping, and pathological study of the proband. Results: The 3 affected family members had a fairly stereotyped clinical course with early personality changes from their late 30s followed within a period of 1–2 years by a progressive cognitive and motor deterioration eventually leading to a state of akinetic mutism or death 3–5 years after the initial symptoms. The main clinical manifestations included severe dementia and hypokinetic-rigid movement disorder associated with supranuclear gaze impairment, pyramidal signs and frontal release signs. Brain imaging disclosed a variable degree of frontotemporal atrophy, ventriculomegaly and regional cerebral hypoperfusion or glucose hypometabolism. Frontal lobe biopsy in the proband revealed weak tau immunoreactivity in a few cortical neurons, in rare neurites and in some glial cells with no neurofibrillary tangles. Molecular DNA analysis identified a P301S mutation in exon 10 of the tau gene. Conclusions: The observed clinical features further expand the reported P301S phenotype and confirm a more aggressive course of the disease than in the other known tau mutations.

Creutzfeldt-Jakob disease profile in patients homozygous for the PRNP E200K mutation.

We identified 70 Creutzfeldt‐Jakob disease patients with the previously described E200K mutation in the prion protein gene. The purpose of this study was to define the clinical features of E200K homozygous patients (n = 5), compared with heterozygotes. We found a statistically significant younger age at disease onset for the homozygous patients, although the average age at onset in this group was still in midlife. Disease features were not statistically different in the two groups. Possible explanations are discussed. Ann Neurol 2000;47:257–260