Anti-α-synuclein immunotherapy reduces α-synuclein propagation in the axon and degeneration in a combined viral vector and transgenic model of synucleinopathy.

Neurodegenerative disorders such as Parkinson's Disease (PD), PD dementia (PDD) and Dementia with Lewy bodies (DLB) are characterized by progressive accumulation of α-synuclein (α-syn) in neurons. Recent studies have proposed that neuron-to-neuron propagation of α-syn plays a role in the pathogenesis of these disorders. We have previously shown that antibodies against the C-terminus of α-syn reduce the intra-neuronal accumulation of α-syn and related deficits in transgenic models of synucleinopathy, probably by abrogating the axonal transport and accumulation of α-syn in in vivo models.

Reducing C-terminal-truncated alpha-synuclein by immunotherapy attenuates neurodegeneration and propagation in Parkinson's disease-like models.

Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are common neurodegenerative disorders of the aging population, characterized by progressive and abnormal accumulation of α-synuclein (α-syn). Recent studies have shown that C-terminus (CT) truncation and propagation of α-syn play a role in the pathogenesis of PD/DLB. Therefore, we explored the effect of passive immunization against the CT of α-syn in the mThy1-α-syn transgenic (tg) mouse model, which resembles the striato-nigral and motor deficits of PD.

β-Amyloid inhibits E-S potentiation through suppression of cannabinoid receptor 1-dependent synaptic disinhibition.

It has been widely reported that β-amyloid peptide (Aβ) blocks long-term potentiation (LTP) of hippocampal synapses. Here, we show evidence that Aβ more potently blocks the potentiation of excitatory postsynaptic potential (EPSP)-spike coupling (E-S potentiation). This occurs, not by direct effect on excitatory synapses or postsynaptic neurons, but rather through an indirect mechanism: reduction of endocannabinoid-mediated peritetanic disinhibition.

Secreted amyloid β-proteins in a cell culture model include N-terminally extended peptides that impair synaptic plasticity.

Evidence for a central role of amyloid β-protein (Aβ) in the genesis of Alzheimer’s disease (AD) has led to advanced human trials of Aβ-lowering agents. The “amyloid hypothesis” of AD postulates deleterious effects of small, soluble forms of Aβ on synaptic form and function. Because selectively targeting synaptotoxic forms of soluble Aβ could be therapeutically advantageous, it is important to understand the full range of soluble Aβ derivatives.

Vascular alterations in PDAPP mice after anti-Aβ immunotherapy: Implications for amyloid-related imaging abnormalities.

Background: Clinical studies of β-amyloid (Aβ) immunotherapy in Alzheimer's disease (AD) patients have demonstrated reduction of central Aβ plaque by positron emission tomography (PET) imaging and the appearance of amyloid-related imaging abnormalities (ARIA). To better understand the relationship between ARIA and the pathophysiology of AD, we undertook a series of studies in PDAPP mice evaluating vascular alterations in the context of central Aβ pathology and after anti-Aβ immunotherapy.

Methods: We analyzed PDAPP mice treated with either 3 mg/kg/week of 3D6, the murine form of bapineuzumab, or isotype control antibodies for periods ranging from 1 to 36 weeks and evaluated the vascular alterations in the context of Aβ pathology and after anti-Aβ immunotherapy.

Axonopathy in an α-synuclein transgenic model of Lewy body disease is associated with extensive accumulation of C-terminal-truncated α-synuclein.

Progressive accumulation of α-synuclein (α-syn) in limbic and striatonigral systems is associated with the neurodegenerative processes in dementia with Lewy bodies (DLB) and Parkinson's disease (PD). The murine Thy-1 (mThy1)-α-syn transgenic (tg) model recapitulates aspects of degenerative processes associated with α-syn accumulation in these disorders. Given that axonal and synaptic pathologies are important features of DLB and PD, we sought to investigate the extent and characteristics of these alterations in mThy1-α-syn tg mice and to determine the contribution of α-syn c-terminally cleaved at amino acid 122 (CT α-syn) to these abnormalities.

AL amyloid imaging and therapy with a monoclonal antibody to a cryptic epitope on amyloid fibrils.

The monoclonal antibody 2A4 binds an epitope derived from a cleavage site of serum amyloid protein A (sAA) containing a -Glu-Asp- amino acid pairing. In addition to its reactivity with sAA amyloid deposits, the antibody was also found to bind amyloid fibrils composed of immunoglobulin light chains. The antibody binds to synthetic fibrils and human light chain (AL) amyloid extracts with high affinity even in the presence of soluble light chain proteins.

Sustained levels of antibodies against Aβ in amyloid-rich regions of the CNS following intravenous dosing in human APP transgenic mice.

Passive immunization with anti-Aβ antibodies leads to the reduction of AD-like neuropathology in transgenic mice. Previously we showed that anti-Aβ antibodies enter the brain and bind to amyloid plaques. Now using (125)I-labeled 3D6, the mouse parent antibody of the clinical candidate bapineuzumab, we further characterized the pharmacokinetic profile of this antibody in the brain and serum.

Neutralization of soluble, synaptotoxic amyloid β species by antibodies is epitope specific.

Several anti-amyloid β (Aβ) antibodies are under evaluation for the treatment of Alzheimer's disease (AD). Clinical studies using the N-terminal-directed anti-Aβ antibody bapineuzumab have demonstrated reduced brain PET-Pittsburg-B signals, suggesting the reduction of Aβ plaques, and reduced levels of total and phosphorylated tau protein in the CSF of treated AD patients. Preclinical studies using 3D6 (the murine form of bapineuzumab) have demonstrated resolution of Aβ plaque and vascular burdens, neuritic dystrophy, and preservation of synaptic density in the transgenic APP mouse models.

Passive immunization reduces behavioral and neuropathological deficits in an alpha-synuclein transgenic model of Lewy body disease.

Dementia with Lewy bodies (DLB) and Parkinson's Disease (PD) are common causes of motor and cognitive deficits and are associated with the abnormal accumulation of alpha-synuclein (α-syn). This study investigated whether passive immunization with a novel monoclonal α-syn antibody (9E4) against the C-terminus (CT) of α-syn was able to cross into the CNS and ameliorate the deficits associated with α-syn accumulation. In this study we demonstrate that 9E4 was effective at reducing behavioral deficits in the water maze, moreover, immunization with 9E4 reduced the accumulation of calpain-cleaved α-syn in axons and synapses and the associated neurodegenerative deficits.

Generation and characterization of anti-AA amyloid-specific monoclonal antibodies.

AA amyloidosis results from the pathologic deposition in the kidneys and other organs of fibrils composed of N-terminal fragments of serum amyloid A protein (SAA). Given that there are only limited means to visualize these deposits, we have developed a series of mAbs, 2A4, 7D8, and 8G9, that bind specifically with nanomolar affinity to a carboxy-terminal epitope generated following proteolysis of SAA that yields the predominant component of AA amyloid deposits. Notably, these antibodies do not recognize native SAA, they retain their immunoreactivity when radiolabeled with I-125 and, after injection into AA amyloidotic mice, localize, as evidenced by autoradiography and micro-single photon emission computed tomography imaging, to histologically confirmed areas of amyloid deposition; namely, spleen, liver, and pancreas.

The role of animal models in advancing amyloid-beta immunotherapy to the clinic.

The amyloid-beta (Aβ) hypothesis of Alzheimer's disease (AD) causality is now well into its third decade and is finally entering a phase of rigorous clinical testing in numerous late stage clinical trials. The use of Aβ-based animal models of AD has been essential to the discovery and/or preclinical validation of many of these therapeutic approaches. While several neuropathologically based results from preclinical studies have translated nicely into AD patients, the full clinical value of Aβ-directed therapies awaits results from trials now in progress.

Structural correlates of antibodies associated with acute reversal of amyloid beta-related behavioral deficits in a mouse model of Alzheimer disease.

Immunotherapy targeting of amyloid beta (Abeta) peptide in transgenic mouse models of Alzheimer disease (AD) has been widely demonstrated to resolve amyloid deposition as well as associated neuronal, glial, and inflammatory pathologies. These successes have provided the basis for ongoing clinical trials of immunotherapy for treatment of AD in humans. Acute as well as chronic Abeta-targeted immunotherapy has also been demonstrated to reverse Abeta-related behavioral deficits assessing memory in AD transgenic mouse models.

Abeta immunotherapy: intracerebral sequestration of Abeta by an anti-Abeta monoclonal antibody 266 with high affinity to soluble Abeta.

Amyloid beta (Abeta) immunotherapy is emerging as a promising disease-modifying therapy for Alzheimer's disease, although the precise mechanisms whereby anti-Abeta antibodies act against amyloid deposition and cognitive deficits remain elusive. To test the "peripheral sink" theory, which postulates that the effects of anti-Abeta antibodies in the systemic circulation are to promote the Abeta efflux from brain to blood, we studied the clearance of (125)I-Abeta(1-40) microinjected into mouse brains after intraperitoneal administration of an anti-Abeta monoclonal antibody 266. (125)I-Abeta(1-40) was rapidly eliminated from brains with a half-life of approximately 30 min in control mice, whereas 266 significantly retarded the elimination of Abeta, presumably due to formation of Abeta-antibody complex in brains.

Immunotherapy reduces vascular amyloid-beta in PDAPP mice.

In addition to parenchymal amyloid-beta (Abeta) plaques, Alzheimer's disease (AD) is characterized by Abeta in the cerebral vasculature [cerebral amyloid angiopathy (CAA)] in the majority of patients. Recent studies investigating vascular Abeta (VAbeta) in amyloid precursor protein transgenic mice have suggested that passive immunization with anti-Abeta antibodies may clear parenchymal amyloid but increase VAbeta and the incidence of microhemorrhage. However, the influences of antibody specificity and exposure levels on VAbeta and microhemorrhage rates have not been well established, nor has any clear causal relationship been identified.

Progress in the active immunotherapeutic approach to Alzheimer's disease: clinical investigations into AN1792-associated meningoencephalitis.

Background: In a phase 2a clinical trial of AN1792 (Study 201), a potential immunotherapeutic agent for use in Alzheimer's disease (AD), approximately 6% of the treated AD patients (18/300) developed meningoencephalitis (ME).

Objective: To elucidate potential immune mechanisms of treatment-induced ME.

Methods: Peripheral blood mononuclear cells obtained from patients who received AN1792 were stimulated in vitro either with beta-amyloid (Abeta) or various overlapping peptides of Abeta(1-42), followed by quantification of cytokine-secreting cells by enzyme-linked immunosorbent spot assay.

Antibody capture of soluble Abeta does not reduce cortical Abeta amyloidosis in the PDAPP mouse.

Background: In vivo administration of antibodies against the amyloid-beta (Abeta) peptide has been shown to reduce and reverse the progressive amyloidosis that develops in a variety of mouse models of Alzheimer's disease (AD). This work has been extended to clinical trials where subsequent autopsy cases of AD subjects immunized against Abeta showed similar reductions in parenchymal amyloid plaques, suggesting this approach to reduce neuropathology in man is feasible.

Objective: Multiple hypotheses have been advanced to explain how anti-Abeta antibodies may lower amyloid burden.

Red blood cells are the major source of alpha-synuclein in blood.

Background: Alpha-synuclein has been directly linked to Parkinson's disease etiology by mutations in and multiplication of its gene that result in a familial form of Parkinson's disease. Alpha-synuclein has been detected in blood, and was found to be elevated in the blood of those individuals with the alpha-synuclein gene multiplication.

Objective: A complete analysis of the level of alpha-synuclein in blood has not been performed.

Effect of statins on Alzheimer's disease biomarkers in cerebrospinal fluid.

Background: Treatment with HMG-CoA reductase inhibitors ("statins") has been variably associated with a reduced risk of Alzheimer's disease (AD) in epidemiologic studies and reduced amyloid-beta (Abeta) deposition in animal models of AD. Putative neuroprotective effects of statins may vary in relation to their ability to penetrate into the central nervous system (CNS).

Methods: We measured levels of cerebrospinal fluid (CSF) AD biomarkers following 14 weeks of treatment with simvastatin (a CNS permeant statin; n=10) at 40 mg/day or pravastatin (a CNS impermeant statin; n=13) at 80 mg/day in hypercholesterolemic subjects without dementia.

Abeta species removal after abeta42 immunization.

Neuropathologic examination of 3 patients with Alzheimer disease in the Elan Pharmaceuticals trial using antibodies specific for different Abeta species showed in one case, 4 months after the immunization, evidence of a stage of active plaque clearance with "moth-eaten" plaques and abundant Abeta phagocytosis by microglia. At 1 to 2 years after immunization, 2 cases showed extensive areas cleared of plaques (69% and 86% of the temporal cortex was plaque-free). Cortex cleared of plaques in all 3 cases had a characteristic constellation of features, including a very low plaque burden, sparse residual dense plaque cores, and phagocytosed Abeta within microglia.

Increased T cell recruitment to the CNS after amyloid beta 1-42 immunization in Alzheimer's mice overproducing transforming growth factor-beta 1.

Immunotherapy targeting the amyloid beta (Abeta) peptide is a novel therapy under investigation for the treatment of Alzheimer's disease (AD). A clinical trial using Abeta(1-42) (AN1792) as the immunogen was halted as a result of development of meningoencephalitis in a small number of patients. The cytokine TGF-beta1 is a key modulator of immune responses that is increased in the brain in AD.

Distribution of Abeta peptide in whole blood.

The measurement of amyloid beta peptides (Abeta) in blood and plasma is expected to be a useful biomarker as potential therapeutics designed to lower Abeta peptide enter clinical trials. Many reports have suggested that Abeta could bind to substances in blood that may influence the recovery of Abeta peptide in plasma, its detection by conventional ELISAs or the actual turnover and half-life of the peptide in blood. In this study we describe a process for analyzing total Abeta in whole blood and plasma using denaturing solid-phase extraction followed by reverse-phase HPLC linked to ELISA.

Mice as models: transgenic approaches and Alzheimer's disease.

Progress in understanding and treating Alzheimer's disease (AD) has been tremendously bolstered by the era of transgenic models of AD. The identification of disease-causing mutations in proteins such as amyloid-beta precursor protein (betaAPP) and presenilin1 (PS1), together with the discovery of other high risk factors (e.g.

A beta immunotherapy: Lessons learned for potential treatment of Alzheimer's disease.

Amyloid-beta (A beta) immunotherapy for treatment of Alzheimer's disease (AD) was first described in 1999 and has been very informative regarding the role of A beta in AD. Through the efforts of many laboratories we now know that it is possible to reduce amyloid burden and many related AD pathologies in numerous animal models of the disease. Furthermore, initial clinical testing with AN1792, composed of A beta(1-42 )and an adjuvant, has yielded very important insights into both the clinical potential of the approach and the impact of A beta peptide on the disease.

Phosphorylation of Ser-129 is the dominant pathological modification of alpha-synuclein in familial and sporadic Lewy body disease.

A comprehensive, unbiased inventory of synuclein forms present in Lewy bodies from patients with dementia with Lewy bodies was carried out using two-dimensional immunoblot analysis, novel sandwich enzyme-linked immunosorbent assays with modification-specific synuclein antibodies, and mass spectroscopy. The predominant modification of alpha-synuclein in Lewy bodies is a single phosphorylation at Ser-129. In addition, there is a set of characteristic modifications that are present to a lesser extent, including ubiquitination at Lys residues 12, 21, and 23 and specific truncations at Asp-115, Asp-119, Asn-122, Tyr-133, and Asp-135.