Intracellular tracing of amyloid vaccines through direct fluorescent labelling

Sci Rep. 2018 Feb 5;8(1):2437. doi: 10.1038/s41598-018-20845-9.

Abstract

Alzheimer's disease is a debilitating neurodegenerative condition that progressively causes synaptic loss and major neuronal damage. Immunotherapy utilising Aβ as an active immunogen or via passive treatment utilising antibodies raised to amyloid have shown therapeutic promise. The migratory properties of peripheral blood-borne monocytes and their ability to enter the central nervous system, suggests a beneficial role in mediating tissue damage and neuroinflammation. However, the intrinsic phagocytic properties of such cells have pre-disposed them to internalise misfolded amyloidogenic peptides that could act as seeds capable of nucleating amyloid formation in the brain. Mechanisms governing the cellular fate of amyloid therefore, may prove to be key in the development of future vaccination regimes. Herein, we have developed unequivocal and direct conformation-sensitive fluorescent molecular probes that reveal the intracytoplasmic and intranuclear persistence of amyloid in a monocytic T helper 1 (THP-1) cell line. Use of the pathogenic Aβ42 species as a model antigen in simulated vaccine formulations suggested differing mechanisms of cellular internalisation, in which fibrillar amyloid evaded lysosomal capture, even when co-deposited on particulate adjuvant materials. Taken collectively, direct fluorescent labelling of antigen-adjuvant complexes may serve as critical tools in understanding subsequent immunopotentiation in vaccines directed against amyloidosis and wider dementia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic / metabolism
  • Aluminum / metabolism
  • Alzheimer Vaccines / chemical synthesis
  • Alzheimer Vaccines / pharmacology*
  • Amyloid beta-Peptides / chemistry
  • Amyloid beta-Peptides / immunology*
  • Amyloid beta-Peptides / metabolism
  • Benzenesulfonates / chemistry
  • Benzothiazoles / chemistry
  • Biological Transport
  • Biomimetic Materials / chemical synthesis
  • Biomimetic Materials / pharmacology*
  • Cell Nucleus / drug effects
  • Cell Nucleus / immunology*
  • Cell Nucleus / ultrastructure
  • Cytoplasm / drug effects
  • Cytoplasm / immunology*
  • Cytoplasm / ultrastructure
  • Fluorescent Dyes / chemistry
  • Humans
  • Hydrogen-Ion Concentration
  • Microscopy, Fluorescence
  • Peptide Fragments / chemistry
  • Peptide Fragments / immunology*
  • Peptide Fragments / metabolism
  • Staining and Labeling / methods*
  • THP-1 Cells

Substances

  • Adjuvants, Immunologic
  • Alzheimer Vaccines
  • Amyloid beta-Peptides
  • Benzenesulfonates
  • Benzothiazoles
  • Fluorescent Dyes
  • Peptide Fragments
  • amyloid beta-protein (1-42)
  • thioflavin T
  • 4-chloro-3-(2,4-dihydroxyphenylazo)-2-hydroxybenzene-1-sulfonic acid
  • Aluminum