Screening Of Phage Peptides Specific For FcεRI-α Receptor On Mast Cell And The Inhibition Of These Peptides In Allergic Reactions

BackgroundAllergic diseases are a large group of diseases in which the body is hypersensitive to certain external substances.They are mainly mediated by IgE antibody.Allergic diseases have now become one of the most common chronic diseases affecting the largest number of people worldwide,seriously affecting their quality of life,causing a huge social and economic burden worldwide and becoming an urgent health problem to be solved.The binding of mast cell surface FcεRI receptor to the specific IgEallergen complex is a key event in the acute and chronic inflammation of allergic diseases,and therefore FcεRI receptor is considered a potential target for the treatment of allergic diseases.Peptide phage display technology is widely used in targeted drug discovery research.The target specific peptides obtained by phage screening have the advantages of smaller molecular weight,less side effects,better structural stability,higher bioavailability and lower production cost.Consequently,peptide phage display technology can be used to obtain FcεRI receptor-specific peptides for targeted therapy of allergic diseases.ObjectiveIn this study,we propose to construct a randomised cyclic octapeptide phage library by phage display technology,to obtain specific high-affinity phage peptides for the FcεRI receptor of IgE on the surface of mast cell membranes after biopanning,and to validate their biological functions.This will lay the foundation for the further development of novel bio-targeted drugs for the treatment of allergic diseases and provide effective therapeutic tools for such diseases.Method(1)Construct and identify a random-loop octapeptide phage library and determine its diversity and capacity to provide a library basis for subsequent biological screening of specific phage peptides.(2)Apply peptide phage display technology to perform three rounds of affinity screening targeting FcεRI-α protein,obtain FcεRI-α protein-specific phage peptides,verify their affinity for the target protein,and then perform gene sequence testing.(3)Based on the DNA sequencing results,the binding ability and affinity between the peptide and the FcεRI-α receptor were predicted at the conformational level by the computer-simulated molecular docking.(4)Prevention and treatment of atopic dermatitis(AD)in mice with FcεRI-α protein-specific peptides to test their biological effects on mast cell-mediated type I allergic reactions.Result(1)The library capacity of the constructed phage-displayed non-natural randomloop octapeptide library was up to 7.4×109 with a cloning efficiency of more than 90%,which was sufficient to cover the diversity of the samples.(2)Six sets of FcεRI-αprotein high affinity phage peptides with different sequences were obtained after biopanning.(3)Molecular docking conformation model based on computer simulation shows a good affinity of the screened peptide to the FcεRI-α protein,among which phage polypeptides A and B had the strongest binding power.(4)Phage peptides A,B,D and F could reduce the degree of inflammation and improve the symptoms of AD to some extent,with peptides A and B having more significant effects.ConclusionThe phage displayed non-natural random-loop octapeptide library constructed in this study has good library capacity and diversity,so it can be used for biopanning based on this library.The peptide obtained from the screening has good affinity with the alpha site of mast cell FcεRI and can effectively alleviate type I allergic inflammation,which provides a new idea for the development of biological small molecule drugs for allergic diseases.