Mapping of Surface-Exposed Epitopes of In Vitro and In Vivo Aggregated Species of Alpha-Synuclein

Development and validation of an expanded antibody toolset that captures alpha-synuclein pathological diversity in Lewy body diseases

The abnormal aggregation and accumulation of alpha-synuclein (aSyn) in the brain is a defining hallmark of synucleinopathies. Various aSyn conformations and post-translationally modified forms accumulate in pathological inclusions and vary in abundance among these disorders. Relying on antibodies that have not been assessed for their ability to detect the diverse forms of aSyn may lead to inaccurate estimations of aSyn pathology in human brains or disease models. To address this challenge, we developed and characterized an expanded antibody panel that targets different sequences and post-translational modifications along the length of aSyn, and that recognizes all monomeric, oligomeric, and fibrillar aSyn conformations. Next, we profiled aSyn pathology across sporadic and familial Lewy body diseases (LBDs) and reveal heterogeneous forms of aSyn pathology, rich in Serine 129 phosphorylation, Tyrosine 39 nitration and N- and C-terminal tyrosine phosphorylations, scattered both to neurons and glia. In addition, we show that aSyn can become hyperphosphorylated during processes of aggregation and inclusion maturation in neuronal and animal models of aSyn seeding and spreading. The validation pipeline we describe for these antibodies paves the way for systematic investigations into aSyn pathological diversity in the human brain, peripheral tissues, as well as in cellular and animal models of synucleinopathies.

Alpha-synuclein in Parkinson's disease and other synucleinopathies: from overt neurodegeneration back to early synaptic dysfunction

Although the discovery of the critical role of α-synuclein (α-syn) in the pathogenesis of Parkinson's disease (PD) is now twenty-five years old, it still represents a milestone in PD research. Abnormal forms of α-syn trigger selective and progressive neuronal death through mitochondrial impairment, lysosomal dysfunction, and alteration of calcium homeostasis not only in PD but also in other α-syn-related neurodegenerative disorders such as dementia with Lewy bodies, multiple system atrophy, pure autonomic failure, and REM sleep behavior disorder. Furthermore, α-syn-dependent early synaptic and plastic alterations and the underlying mechanisms preceding overt neurodegeneration have attracted great interest. In particular, the presence of early inflammation in experimental models and PD patients, occurring before deposition and spreading of α-syn, suggests a mechanistic link between inflammation and synaptic dysfunction. The knowledge of these early mechanisms is of seminal importance to support the research on reliable biomarkers to precociously identify the disease and possible disease-modifying therapies targeting α-syn. In this review, we will discuss these critical issues, providing a state of the art of the role of this protein in early PD and other synucleinopathies.

Peptide-Based Vaccines for Neurodegenerative Diseases: Recent Endeavors and Future Perspectives

The development of peptide-based vaccines for treating human neurodegenerative diseases has been the eventual aim of many research endeavors, although no active immunotherapies have been approved for clinical use till now. A typical example of such endeavors is the effort to develop vaccines for Alzheimer’s disease based on the beta-amyloid peptide, which continues to be intensively investigated despite previous setbacks. In this paper, recent developments in peptide-based vaccines which target beta-amyloid as well as tau protein and α-synuclein are presented. Particular focus has been directed toward peptide epitopes and formulation systems selected/developed and employed to enhance vaccine efficacy and safety. Results from both, human clinical trials and animal preclinical studies conducted mainly in transgenic mice have been included. Future perspectives on the topic are also briefly discussed.

ABBV-0805, a novel antibody selective for soluble aggregated α-synuclein, prolongs lifespan and prevents buildup of α-synuclein pathology in mouse models of Parkinson's disease

A growing body of evidence suggests that aggregated α-synuclein, the major constituent of Lewy bodies, plays a key role in the pathogenesis of Parkinson's disease and related α-synucleinopathies. Immunotherapies, both active and passive, against α-synuclein have been developed and are promising novel treatment strategies for such disorders. Here, we report on the humanization and pharmacological characteristics of ABBV-0805, a monoclonal antibody that exhibits a high selectivity for human aggregated α-synuclein and very low affinity for monomers. ABBV-0805 binds to a broad spectrum of soluble aggregated α-synuclein, including small and large aggregates of different conformations. Binding of ABBV-0805 to pathological α-synuclein was demonstrated in Lewy body-positive post mortem brains of Parkinson's disease patients. The functional potency of ABBV-0805 was demonstrated in several cellular assays, including Fcγ-receptor mediated uptake of soluble aggregated α-synuclein in microglia and inhibition of neurotoxicity in primary neurons. In vivo, the murine version of ABBV-0805 (mAb47) displayed significant dose-dependent decrease of α-synuclein aggregates in brain in several mouse models, both in prophylactic and therapeutic settings. In addition, mAb47 treatment of α-synuclein transgenic mice resulted in a significantly prolonged survival. ABBV-0805 selectively targets soluble toxic α-synuclein aggregates with a picomolar affinity and demonstrates excellent in vivo efficacy. Based on the strong preclinical findings described herein, ABBV-0805 has been progressed into clinical development as a potential disease-modifying treatment for Parkinson's disease.

Gene Dysfunction Mediates Immune Response to Dopaminergic Degeneration in Parkinson's Disease

Many publications reported that genetic dysfunction mediates abnormal immune responses in the brain, which is important for the development of neurodegenerative diseases, especially for Parkinson's disease (PD). This immune disorder results in subsequent inflammatory reaction, which stimulates microglia or other immune cells to secrete cytokines and chemokines and disturbs the proportion of peripheral blood lymphocyte subsets contributing to dopaminergic (DA) neuron apoptosis. Furthermore, the abnormal immune related signal pathways caused by genetic variants promote chronic inflammation destroying the blood-brain barrier, which allows infiltration of different molecules and blood cells into the central nervous system (CNS) exerting toxicity on DA neurons. As a result, the inflammatory reaction in the CNS accelerates the progression of Parkinson's disease and promotes α-synuclein aggregation and diffusion among DA neurons in the procession of Parkinson's disease. Thus, for disease evaluation, the genetic mediated abnormal immune response in PD may be assessed based on the multiple immune molecules and inflammatory factors, as well as the ratio of lymphocyte subsets from PD patient's peripheral blood as potential biomarkers.

The Role of Lipids in Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disease characterized by a progressive loss of dopaminergic neurons from the nigrostriatal pathway, formation of Lewy bodies, and microgliosis. During the past decades multiple cellular pathways have been associated with PD pathology (i.e., oxidative stress, endosomal-lysosomal dysfunction, endoplasmic reticulum stress, and immune response), yet disease-modifying treatments are not available. We have recently used genetic data from familial and sporadic cases in an unbiased approach to build a molecular landscape for PD, revealing lipids as central players in this disease. Here we extensively review the current knowledge concerning the involvement of various subclasses of fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, and lipoproteins in PD pathogenesis. Our review corroborates a central role for most lipid classes, but the available information is fragmented, not always reproducible, and sometimes differs by sex, age or PD etiology of the patients. This hinders drawing firm conclusions about causal or associative effects of dietary lipids or defects in specific steps of lipid metabolism in PD. Future technological advances in lipidomics and additional systematic studies on lipid species from PD patient material may improve this situation and lead to a better appreciation of the significance of lipids for this devastating disease.