Methods for detecting Aβ oligomers
Methods of detecting Aβ oligomers, such as may be present in a biological sample are described. The methods include detection using flow cytometry, detection using synthetic Aβ oligomers and/or in vitro methods detecting Aβ oligomers associated with cells.
1. A method of determining the amyloid beta (Aβ) oligomer load of a subject by detecting Aβ oligomer associated with cells present in a biological sample obtained from the subject, comprising:
preparing a first test sample comprising a biological sample from the subject that comprises cells and a peptide probe,
wherein the peptide probe consists of from 10 to 34 amino acid residues comprising an amino acid sequence that is at least 70% identical to any one of SEQ ID NOs:1-56 and 62-65, wherein the peptide probe preferentially binds to Aβ oligomers and is labeled with a detectable fluorescent label, wherein the peptide probe forms a first labeled complex with the Aβ oligomers on Aβ oligomer-associated cells in the biological sample;
detecting a generated signal of the first labeled complex in the first test sample using flow cytometry;
preparing a second test sample comprising a biological sample from the subject that comprises cells, synthetic Aβ oligomer, and the peptide probe, wherein the peptide probe forms second labeled complexes with Aβ oligomers on Aβ oligomer-associated cells in the biological sample and with synthetic Aβ oligomer;
detecting a generated signal of the second labeled complexes in the second test sample using flow cytometry;
wherein a difference between the signal of the first labeled complex in the first test sample and the signal of the second labeled complexes in the second test sample is inversely correlated with the Aβ oligomer load of the subject.
2. The method according to claim 1 , wherein the second test sample is prepared by combining the biological sample and synthetic Aβ oligomer, and subsequently introducing the peptide probe.
3. The method according claim 1 , wherein the peptide probe consists of SEQ ID NO:64 (Pep-11).
4. The method according to claim 1 , wherein the fluorescent label is a fluorescein isothiocyanate (FITC) label.
5. The method according to claim 1 , wherein the biological sample comprises a sample of body fluid.
6. The method according to claim 5 , wherein the body fluid is selected from the group consisting of blood, blood plasma, cerebrospinal fluid (CSF), and brain homogenate.
7. The method according to claim 5 , wherein the body fluid comprises Aβ oligomer-associated erythrocytes.
8. The method according to claim 7 , wherein the erythrocytes arc isolated erythrocytes.
9. The method according to claim 5 , wherein the body fluid comprises Aβ oligomer-associated platelets.
10. The method according to claim 9 , wherein the platelets are isolated platelets.
11. The method according to claim 2 , wherein the biological sample comprises Aβ oligomer-associated cells selected from erythrocytes, platelets, leukocytes and tissue cells.
12. The method according to claim 11 , wherein the biological sample comprises Aβ oligomer-associated erythrocytes and Aβ oligomer-associated platelets and the detecting comprises separately detecting Aβ oligomers associated with erythrocytes and Aβ oligomers associated with platelets.
13. The method according to claim 1 , wherein the labeled complex formed and/or detected is selected from a labeled complex comprising peptide probe and Aβ oligomer on Aβ oligomer-associated erythrocytes from the biological sample; a labeled complex comprising peptide probe and Aβ oligomer on Aβ oligomer-associated platelets from the biological sample; and a labeled complex comprising peptide probe and synthetic Aβ oligomer on synthetic Aβ oligomer-associated erythrocytes or on synthetic Aβ oligomer-associated platelets from the biological sample.
14. An in vitro method of detecting amyloid beta (Aβ) oligomer associated with erythrocytes or platelets, comprising:
contacting erythrocytes or platelets with a peptide probe,
wherein the peptide probe consists of from 10 to 34 amino acid residues comprising an amino acid sequence that is at least 70% identical to any one of SEQ ID NOs:1-56 and 62-65, wherein the peptide probe preferentially binds to Aβ oligomers and is labeled with a detectable label, wherein the peptide probe forms a labeled complex with the Aβ oligomers on Aβ oligomer-associated erythrocytes or Aβ oligomer-associated platelets; and
detecting a generated signal of the labeled complex using flow cytometry.