Compositions and methods of inhibiting the binding of plasma IgG autoantibodies to serotonin 2A receptor

1. A decoy peptide consisting of the sequence of QDDSKVFKEGSCLLADDN (SEQ ID NO: 1), or a fragment thereof, wherein the fragment of SEQ ID NO: 1 consists of 4 to 9 amino acids in length, and wherein the decoy peptide inhibits the binding of 5-HT2A receptor autoantibodies to a second extracellular loop region of the 5-HT2A receptor.

2. The decoy peptide of claim 1 , wherein the fragment of SEQ ID NO: 1 consists of the sequence SCLLADDN (SEQ ID NO: 2), QDDSKVF (SEQ ID NO: 3), or VFKEGSC (SEQ ID NO: 4).

3. The decoy peptide of claim 1 , wherein the decoy peptide inhibits the binding of a 5-HT2A receptor autoantibodies to a second extracellular loop region of the 5-HT2A receptor by competitive inhibition.

4. The decoy peptide of claim 1 , wherein at least one amino acid residue of the decoy peptide comprises an acetyl group, a fluorenylmethoxy carbonyl group, a formyl group, a palmitoyl group, a myristyl group, a stearyl group, or polyethylene glycol.

5. A pharmaceutical composition comprising the decoy peptide of claim 1 , and a pharmaceutically acceptable carrier.

6. A method of treating a subject with a disease or disorder, the method comprising: administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising a decoy peptide comprising the sequence of SEQ ID NO: 2 and a pharmaceutically acceptable carrier, wherein the disease or disorder is a metabolic disease or disorder, a cardiovascular or a microvascular disease or disorder, or a neurodegenerative disease or disorder.

7. The method of claim 6 , wherein the cardiovascular or the microvascular disease or disorder is a stroke, kidney dysfunction, kidney failure, age-related macular degeneration, diabetic macular edema, diabetic nephropathy, microvascular angiopathy, hypertension, painful neuropathy, or hypertensive nephropathy.

8. The method of claim 6 , wherein the neurodegenerative disease or disorder is open angle glaucoma, dementia, Parkinson's disease, macular degeneration, or retinal degeneration.

9. The method of claim 6 , wherein the metabolic disease or disorder is diabetes.

10. The method of claim 6 , wherein the subject is obese or has a traumatic brain injury, type 2 diabetes, hypertension, microvascular angiopathy, painful neuropathy, Parkinson's disease, dementia, major depressive disorder, schizophrenia, retinitis pigmentosa, refractory hypertension, mild cognitive dysfunction, primary open angle glaucoma or previously had a stroke or a traumatic brain injury or a combination thereof.

11. The method of claim 6 , wherein the subject has one or more 5-HT2A receptor autoantibodies.

12. The method of claim 6 , wherein administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising a decoy peptide comprising SEQ ID NO: 2 and a pharmaceutically acceptable carrier lowers blood pressure in the subject.

13. The method of claim 6 , wherein the administration of the therapeutically effective amount of the pharmaceutical composition promotes or induces weight loss in the subject or improves short term memory in the subject.

14. The method of claim 6 , further comprising administering a therapeutically effective amount of ketanserin or volinanserin to the subject.

15. The method of claim 6 , wherein at least one amino acid residue of the decoy peptide comprises an acetyl group, a fluorenylmethoxy carbonyl group, a formyl group, a palmitoyl group, a myristyl group, a stearyl group, or polyethylene glycol.

16. A method of treating a subject with a neurologic disease or disorder, the method comprising: administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising a decoy peptide comprising the sequence of SEQ ID NO: 2 and a pharmaceutically acceptable carrier, wherein the neurologic disease or disorder is neuropathy, dementia, major depressive disorder or Parkinson's disease.

17. The method of claim 16 , further comprising administering a therapeutically effective amount of ketanserin or volinanserin to the subject.

18. The method of claim 16 , wherein at least one amino acid residue of the decoy peptide comprises an acetyl group, a fluorenylmethoxy carbonyl group, a formyl group, a palmitoyl group, a myristyl group, a stearyl group, or polyethylene glycol.

19. A method of inducing sedation in a subject, the method comprising administering to the subject a therapeutically effective amount of a pharmaceutical composition comprising a decoy peptide comprising SEQ ID NO: 2, and a pharmaceutically acceptable carrier.

20. The method of claim 19 , wherein at least one amino acid residue of the decoy peptide comprises an acetyl group, a fluorenylmethoxy carbonyl group, a formyl group, a palmitoyl group, a myristyl group, a stearyl group, or polyethylene glycol.