or a pharmaceutically acceptable salt or ester thereof xaa4 is absent ala gly val leu ile or pro for the use according to the first aspect of the invention or used in the pharmaceutical composition according to the second aspect of the invention in the formula preferably xaa1 is gly xaa2 is thr xaa3 is tyr and xaa4 is absent ala or gly more preferably xaa4 is absent the peptide of the invention is a purified peptide with at least 80 pure preferably at least 90 pure more preferably at least 95 pure and particularly with pharmaceutical purity i e at least 98 pure and pathogen free and pyrogen free preferably the peptide of the invention may substantially comprise no other polypeptides or proteins especially those derived from animals furthermore in the fourth aspect the invention provides a polynucleotide encoding the peptide according to the third aspect of the invention a u201c polynucleotide u201d used herein refers to a single stranded or double stranded polymer of deoxyribonucleotides or ribonucleotides with the sequence reading from 5 u2032 end to 3 u2032 end including rna and dna it may be prepared by isolation from the natural source in vitro synthesis or recombinant expression in the fifth aspect the invention provides a method of manufacturing a peptide or a pharmaceutically acceptable salt or ester thereof according to the third aspect of the invention wherein the method comprises the step of chemically synthesizing the said peptide or expressing the said peptide in the fusion form the method of manufacturing of the invention may further comprise a reaction step for generating the said salt or ester from the said peptide it is obvious for a skilled person.