Factor H binding peptides and uses thereof

1. A peptide that binds factor H without interfering with a biological activity of factor H, wherein the biological activity comprises inhibiting complement activation; wherein the peptide is Formula I:

Z—U  Formula I:

wherein:

U is a cysteine cyclic peptide comprising: Cys-Xaa1-Tyr-Xaa2-Xaa3-Trp-Cys-Xaa4-His (SEQ ID NO:1) wherein:

Xaa1 is any amino acid;

Xaa2 is Asp or Ser;

Xaa3 is His or Tyr; and

Xaa4 is any amino acid; and

Z is absent or is a peptide comprising: Ala-Ser-Xaa5-Xaa6-Xaa7 (SEQ ID NO:2) wherein:

Xaa5 is Ser or Pro;

Xaa6 is absent or is any amino acid; and

Xaa7 is absent or is any amino acid;

wherein Z, if present, and U are joined by a peptide bond.

2. The peptide of claim 1 , wherein the peptide is less than about 20 amino acid residues in length.

3. The peptide of claim 2 , wherein the peptide is less than about 15 amino acid residues in length.

4. The peptide of claim 1 , wherein Xaa1 is Thr, Ser, Asp or Met.

5. The peptide of claim 1 , wherein Xaa4 is Ser, Arg, Leu, Ala or Thr.

6. The peptide of claim 1 , wherein Xaa6 is Ser, Phe or Asn.

7. The peptide of claim 1 , wherein Xaa7 is Arg, Trp, Lys or Val.

8. The peptide of claim 1 , comprising a sequence selected from:

(SEQ ID NO: 3)

ASSSRCTYDHWCSH;

(SEQ ID NO: 4)

ASPSWCSYSHWCRH;

(SEQ ID NO: 5)

ASSFKCDYSHWCLH;

(SEQ ID NO: 6)

ASSNVCSYSYWCAH;

and

(SEQ ID NO: 7)

ASSCMYSYWCTH.

9. A composition comprising the peptide of claim 1 affixed to a biomaterial.

10. The composition of claim 9 , wherein the biomaterial comprises one or more of polymers, plastics, metals, ceramics, artificial tissues and organs, or living cells, tissues and organs.

11. The composition of claim 9 , wherein the peptide is reversibly affixed to the biomaterial.

12. A method of reducing complement activation in a biological substance that is exposed to a biomaterial, the method comprising:

(a) affixing to the biomaterial a peptide that binds factor H without interfering with the ability of the factor H to inhibit complement activation, thereby forming a peptide-coated biomaterial; wherein the peptide is Formula I:

Z—U  Formula I:

wherein:

U is a cysteine cyclic peptide comprising: Cys-Xaa1-Tyr-Xaa2-Xaa3-Trp-Cys-Xaa4-His (SEQ ID NO:1) wherein:

Xaa1 is any amino acid;

Xaa2 is Asp or Ser;

Xaa3 is His or Tyr; and

Xaa4 is any amino acid; and

Z is absent or is a peptide comprising: Ala-Ser-Xaa5-Xaa6-Xaa7 (SEQ ID NO:2) wherein:

Xaa5 is Ser or Pro;

Xaa6 is absent or is any amino acid; and

Xaa7 is absent or is any amino acid;

wherein Z, if present, and U are joined by a peptide bond;

(b) contacting the peptide coated biomaterial with factor H, whereupon the factor H is bound to the peptide on the peptide-coated biomaterial, thereby forming a factor H-enriched biomaterial; and

(c) exposing the biological substance to the factor H-enriched biomaterial, whereupon the complement activation in the exposed biological substance is reduced in comparison to an equivalent biological substance exposed to an equivalent biomaterial that has not been affixed with the peptide and contacted with the factor H.

13. The method of claim 12 , wherein the biological substance contains the factor H, and the contacting is accomplished when the biological substance is exposed to the peptide-coated biomaterial.

14. The method of claim 13 , wherein the biological substance is blood or a component of blood.

15. The method of claim 12 , comprising performing the contacting before exposing the biological substance to the peptide-coated biomaterial.

16. The method of claim 15 , wherein the biological substance is a tissue or organ.