Conformational studies on Amyloid β Oligomers in Alzheimer's disease

Aβ Oligomers (AβOs) are polymorphic assembly states of the Aβ peptide, which act as neurotoxic molecules in Alzheimer’s disease (AD) pathogenesis. We are investigating AβOs by multilevel conformational studies.

Alzheimer’s disease is the prevailing cause of dementia, traditionally defined by the combined presence of extracellular Aβ plaques and intraneuronal tau in affected brains. While the linear causality proposed by the original amyloid hypothesis is showing several criticisms and controversies, it is well accepted that when Aβ undergoes aggregation is more neurotoxic through its oligomers (AβOs) instead of large fibrils composing plaques in brains.

Nevertheless, several issues remain to be addressed on mechanisms of oligomerization both in vitro and in vivo. For this reason, in my laboratory we are investigating different aspects of AβOs by the use of small antibody fragments, called anti-AβO nanobodies, developed in collaboration with Cattaneo group. Of note, anti-AβO nanobodies are intrinsically equipped with unique features of conformation-sensitivity and sequence-specificity. 

1. Studies on Alzheimer’s human brains

With the aim of identifying new pathological relevant AβO structural variants and conformational epitopes, we are investigating post-mortem human brains from patients affected by Alzheimer’s disease, also in condition of co-morbidities, at different stages of pathology and in several areas of brain cortex, by different approaches of microscopy and biochemistry. In brain slices labeled with anti-AβO nanobodies we are able to reveal, by super-resolution confocal microscopy, new patterns of AβO deposition largely complementary to extracellular Aβ plaques detected by generic amyloid dyes and other anti-Aβ antibodies. Engineering of nanobodies for direct labeling procedures is also in progress in collaboration with Cattaneo’s lab.

2. Conformational studies in vitro: towards assays on biological fluids for innovative biomarkers

Antibody-based assays in vitro are essential to study pathways and mechanisms of Aβ oligomerization and to identify in a selective way different structural AβO epitopes/subtypes. Starting from conformation-sensitive and sequence-specific assays for synthetic and natural AβO samples, we recently established new nanobody-assays more sensitive and exploitable in biological fluids. Current efforts are focusing on their uses in translational Alzheimer’s disease research to improve the established core cerebrospinal biomarkers based on Aβ42 and tau. 

3. Studies on intracellular Aβ oligomers in human cells

We are performing studies on subcellular mechanisms of formation, trafficking and action of endogenous O in human primary cells derived from patients and ex vivo reprogrammed induced Pluripotent Stem Cells (iPSCs), with a main focus on mechanisms driven by the Endoplasmic Reticulum. Here, anti-AβO nanobodies are exploited as tools for “Conformational-Selective Interference” (CSI), approach pioneered in collaboration with Antonino Cattaneo and based on the subcellular targeting of a conformation-sensitive intrabody in living cells and in vivo.

Other collaborative projects

Human Brain Project: development and uses of innovative nanobodies targeting proteins of trans-synaptic signaling (i.e. Neuroligins, Neurexins, Gephyrin) as tools for brain imaging and intrabody-interference.

Group Leader

Giovanni Meli

Annalisa Manca
Elena Fiori Micaela Lucarelli