Immunotherapeutics for AD: A Work in Progress

Dual Targeting of Soluble Oligomeric and Aggregated Transthyretin with a Monoclonal Antibody Ameliorates Experimental Neuropathy

ATTR amyloidosis comprises a spectrum of multiple clinical presentations, including, predominantly, neuropathy and cardiomyopathy. The common triggering pathogenic protein is misfolded transthyretin, a carrier protein that destabilizes misfolds and assembles into mature amyloid fibrils. The current management of ATTR amyloidosis includes the use of agents that stabilize TTR or attenuate its liver inducible production. Herein, we tested the hypothesis that a monoclonal antibody targeting the soluble oligomeric as well as the aggregated TTR would influence experimental neuropathy. We have shown that Ab-A, our previously described humanized IgG monoclonal antibody, dose-dependently ameliorates the toxicity to neurons triggered by misfolded TTR oligomers. Furthermore, the antibody that exhibits wide misTTR epitope recognition that includes the oligomeric and aggregated forms of the protein dose-dependently enhances the uptake of misfolded TTR to microglia, the resident predominant cells of the innate immune system within the CNS. These in vitro mechanistic properties of the antibody were corroborated by experimental in vivo data showing that the antibody rapidly clears human TTR amyloid extracts infiltrated to the sciatic nerves of rats. Thus, the monoclonal antibody targeting soluble and aggregated TTR is effective in experimental neuropathy, likely due its ability to act as a neuroprotective agent, as well its misTTR-mediated clearance via microglia.

News about Therapies of Alzheimer’s Disease: Extracellular Vesicles from Stem Cells Exhibit Advantages Compared to Other Treatments

Upon its discovery, Alzheimer’s, the neurodegenerative disease that affects many millions of patients in the world, remained without an effective therapy. The first drugs, made available near the end of last century, induced some effects, which remained only marginal. More promising effects are now present, induced by two approaches. Blockers of the enzyme BACE-1 induce, in neurons and glial cells, decreased levels of Aβ, the key peptide of the Alzheimer’s disease. If administered at early AD steps, the BACE-1 blockers preclude further development of the disease. However, they have no effect on established, irreversible lesions. The extracellular vesicles secreted by mesenchymal stem cells induce therapy effects analogous, but more convenient, than the effects of their original cells. After their specific fusion to target cells, the action of these vesicles depends on their ensuing release of cargo molecules, such as proteins and many miRNAs, active primarily on the cell cytoplasm. Operationally, these vesicles exhibit numerous advantages: they exclude, by their accurate selection, the heterogeneity of the original cells; exhibit molecular specificity due to their engineering and drug accumulation; and induce effective actions, mediated by variable concentrations of factors and molecules and by activation of signaling cascades. Their strength is reinforced by their combination with various factors and processes. The recent molecular and operations changes, induced especially by the stem cell target cells, result in encouraging and important improvement of the disease. Their further development is expected in the near future.