Self-assembled Peptide Nanostructures Bind IgE For Inhibiting Allergic Rhinitis By DING Mengru

Allergic rhinitis(AR)is a chronic inflammatory reaction by Immunoglobulin E(Ig E)mediators after individual contact with allergens.The main symptoms are paroxysm of sneezing,nasal congestion,nasal itching,runny nose,sometimes accompanied by itching eyes,tearing.Long-term symptoms of rhinitis can cause inflammation to spread and trigger asthma,which can harm human health.With the development of industrialization,environment is further polluted,which can increase the risk of AR.AR affects 10 to 40% of adults in the world and perhaps a somewhat higher percentage of children.Herein,we developed a smart defensive peptide net technique based on BIF peptides,which was able to trap Ig E and inhibit the binding between Ig E and FcεRI against AR.When the allergen contacts the organism for the first time,B cells secrete Ig E,and Ig E bind to FcεRI on the mast cell membrane to make the body sensitized.When the allergen contacts the organism again,the allergen binds to the Ig E on the mast cells,leading to the cross-linking of Ig E-FcεRI complex.As a result,mast cells release inflammatory factors(histamine,IL-4 etc.),causing allergic reactions.In turn,the released IL-4 activates B cells again,causing B cells to secrete more Ig E in situ in the nasal tissue to exacerbate allergic reactions.Herein,we designed two Ig E defensive peptides,SPIN-1and SPIN-2.They are composed of three parts: a hydrophobic fragment with a bipyrene molecule(BP)as the core,an assembled fragment of KLVFF used to form stable fibers,and two different target fragments that bind to Ig E,SILPVDAKDWIEGEG and HPEYAVSVLL.Among them,BP has strong hydrophobicity and π-π stacking effect,which provides a driving force for the formation of nanoparticles by self-assembly;β-sheet sequence of KLVFF provided both hydrogen-bonding interactions and hydrophobicity,inducing the transformation of nanoparticles into nanofibers(NFs);SILPVDAKDWIEGEG and HPEYAVSVLLVNTANST targeting fragments can bind to Ig E.SPIN-1 or SPIN-2 in the formulation of NPs was able to bind to Ig E and transform into NFs,forming entangled fibrous networks in nasal mucosa.In turn,the fibrous networks were able to trap Ig E to inhibit Ig E binding to mast cells,and corresponding AR.Through FL,UV-Vis,TEM、CD and FT-IR characterization,the self-assembly and morphological transformation of defense peptides SPIN-1and SPIN-2 in water environment were explored.SPIN-1/SPIN-2 self-assembled to form nanoparticles in aqueous environment,and after interacting with Ig E,the nanoparticles transformed into nanofiber networks with β-sheet structure.Through the incubation of SPIN-1/SPIN-2 and trypsin for 5 d,it was found that the fiber networks of E1 were broken on day 3,while the fibers of SPIN-2 degraded on day 5,indicating that SPIN-2 had higher enzymatic stability than SPIN-1.GICT experiment and TEM characterization verified that the defense peptide SPIN-1/SPIN-2 captured Ig E.After SPIN-1/SPIN-2 and Ig E-Au were incubated for 2d,TEM images showed that Ig E-Au were hanging on the defense peptide net.It was proved that SPIN-1/SPIN-2 could trap Ig E effectively.In the cell experiment,the biological functionalities were verified by CLSM assays.CLSM imaging found that the fluorescent signal of SPIN-1/SPIN-2 overlaps with that of Ig E,while blocking the binding of Ig E to LAD2.Which proved that SPIN-1/SPIN-2 could target Ig E and block the binding of Ig E to mast cells.The fluorescence signal of SPIN-1/SPIN-2 overlaps with the fluorescence signal of Ig E,while blocking the binding of Ig E to LAD2,which proves that SPIN-1/SPIN-2 can target Ig E and block the binding of Ig E to mast cells.In animal experiments,compared with clinical first-line drug cetirizine,SPIN-1and SPIN-2 exhibited better therapeutic effect,proven by alleviation of typical AR symptoms,reduction of inflammatory cytokines in serum as well as infiltration of representative proinflammatory cells in nasal tissue.For example,the release of IL-4 in the AR group was 185.5 ± 6.8 pg/m L,the release of IL-4 in the cetirizine group was 112.8 ± 19.3 pg/m L,and the release of IL-4 in the SPIN-1 and SPIN-2 groups were 70.4 ± 14.1 pg/m L and 86.0 ± 9.3 pg/m L,respectively.More importantly,SPIN-1 and SPIN-2 exhibited long-term inhibition of AR up to one weak,which was one day for cetirizine,probably due to the both high efficiency and long retention of defensive peptide nets.Specifically,SPIN-2 with higher enzymatic stability had better long-term inhibition effect than SPIN-1.It was found that there were no significant lesion in heart,liver,spleen and kidney tissues of the mice treated with SPIN-1/SPIN-2,proving that SPIN-1/SPIN-2 has good biological safety.