Specific binding polypeptide of targeted cell membrane receptor Fc epsilon RI alpha and application of specific binding polypeptide

Abstract

The invention provides a specific binding polypeptide of a targeted cell membrane receptor Fc epsilon RI alpha and application of the specific binding polypeptide. The amino acid sequence of the polypeptide is shown in any one of (I) SEQ ID NO: 1-6; (II) an amino acid sequence with at least 90% identity as shown in any one of SEQ ID NO: 1-6, and is specifically combined with a cell membrane receptor Fc epsilon RI alpha. Experimental results show that the Fc [epsilon] RI [alpha] specific binding polypeptide can inhibit IgE-mediated mast cell dependent anaphylaxis to a certain extent, which prompts that the Fc [epsilon] RI [alpha] specific binding polypeptide has a certain inhibition effect on IgE-mediated I-type anaphylaxis, and lays a foundation for further research and development of novel biological targeting drugs for treating allergic diseases.

Description

Technical Field

[0001] The present invention belongs to the field of biomedicine, and in particular relates to a specific binding polypeptide targeting a cell membrane receptor FcεRIα and an application thereof. Background Art

[0002] Allergic diseases, primarily IgE-mediated hypersensitivity to certain external substances, include allergic rhinitis (AR), allergic asthma (AA), IgE-mediated food allergies, and atopic dermatitis. They have become one of the most common chronic diseases worldwide, affecting over 20% of the world's population. They severely impact quality of life, impose a significant social and economic burden, and represent a pressing health challenge. The binding of FcεRI receptors on the surfaces of mast cells and basophils to specific IgE-allergen complexes triggers mast cell activation, leading to the onset of allergic reactions, a key event in the acute and chronic inflammation of allergic diseases. Therefore, the FcεRI receptor has become an important biological target for regulating allergic reactions.

[0003] The WHO-recommended "four-in-one" combination for treating allergic diseases still has certain flaws. First, it's difficult for patients to completely avoid allergen exposure; conventional symptomatic drug treatments have certain toxic side effects and cannot achieve a complete cure; specific immunotherapy is time-consuming and expensive, and standardized allergen vaccines are incomplete; and compliance with health education is poor. Therefore, the key to allergic disease treatment research lies in finding more low-cost, safe, and effective biologically targeted drugs that not only relieve allergic symptoms but also fundamentally inhibit allergic reactions.

[0004] Phage display technology can be used to biopannally identify peptides that specifically bind to FcεRIα. Phage display involves fusing a gene encoding a random foreign polypeptide chain to a phage coat protein gene, resulting in the expression of the peptide as a fusion protein on the phage surface. The peptide maintains a relatively independent spatial structure and biological activity, thereby generating a large library of random peptides. During the panning process, the phage peptide library is incubated with a specific target. Unbound phage are removed by washing, and target-bound phage are eluted using a ligand for the target protein. Appropriate host cells are then selected for propagation and amplification. After three rounds of biopanning, phage clones with high-affinity binding to the target protein are obtained.

[0005] Phage display technology is widely used in targeted drug development research. Compared with traditional antibody-based targeting molecules, specific peptides obtained through phage display screening offer advantages such as smaller molecular weight, fewer side effects, higher bioavailability, and lower production costs. These peptides can be used to identify peptides specific for the FcεRI receptor, potentially offering potential for the targeted treatment of allergic diseases. To date, there have been no reports of using phage display library technology to screen for peptides that specifically bind to the cellular FcεRIα protein. Therefore, providing a series of peptides that specifically bind to the cellular FcεRIα protein would have significant application value in the treatment of allergic diseases. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention aims to provide a specific binding polypeptide targeting the cell membrane receptor FcεRIα and its application. Based on in vitro phage display technology, the present invention constructs a non-natural random octapeptide library with good library capacity and diversity, which can be used to obtain ideal target peptides with high affinity and high specificity for the target molecule through biopanning. The specific peptides obtained by screening have advantages such as small molecular weight, minimal side effects, stable structure, high bioavailability, and low production cost, overcoming the shortcomings of conventional treatments for allergic diseases.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a specific binding polypeptide targeting a cell membrane receptor FcεRIα, wherein the amino acid sequence of the polypeptide comprises:

[0009] (I) any one of SEQ ID NOs: 1-6;

[0010] (II) an amino acid sequence that is at least 90% identical to any one of SEQ ID NOs: 1-6 and specifically binds to the cell membrane receptor FcεRIα.

[0011] The present invention firstly uses a random octapeptide mutation library with large library capacity and good diversity constructed in the early stage to perform affinity screening with the high-affinity IgE receptor FcεRIα on the mast cell membrane as the target protein, and then performs sequencing identification and ELISA binding test on it. The specific binding polypeptides targeting the cell membrane receptor FcεRIα (FcεRIα specific binding polypeptides) with different sequences are obtained, and the amino acid sequences are as follows:

[0012] Polypeptide A: SEQ ID NO: 1: PFPLHFFA;

[0013] Polypeptide B: SEQ ID NO: 2: QLKAGSIH;

[0014] Polypeptide C: SEQ ID NO: 3: LPWALSLA;

[0015] Polypeptide D: SEQ ID NO: 4: TVDSSPPL;

[0016] Polypeptide E: SEQ ID NO: 5: WSPLLWVR;

[0017] Polypeptide F: SEQ ID NO: 6: WNFWNLRA.

[0018] Preferably, the polypeptide specifically binds to the α site of FcεRI and inhibits IgE-mediated type I hypersensitivity reaction.

[0019] Preferably, the polypeptide inhibits mast cell activation and degranulation.

[0020] Preferably, the polypeptide improves inflammatory responses and allergic symptoms.

[0021] This study used ovalbumin combined with calcipotriol to induce an atopic dermatitis (AD) mouse model. Six FcεRIα-specific binding peptides and the mast cell membrane stabilizer ketotifen were used to treat the AD mice. Ear thickness, ear lesions, mast cell counts, and inflammatory infiltration in the ear skin were assessed across the groups. The results showed that FcεRIα-specific binding peptides A, B, D, and F could alleviate and improve ear inflammation and allergic symptoms in AD mice to a certain extent. Phage peptides A and B were more effective, demonstrating a robust therapeutic effect in AD mice.

[0022] The present invention also detects the cytotoxicity of the polypeptide through the CCK8 experiment, and then constructs an in vitro mast cell activation model through the mode of anti-2,4-dinitrophenol (2,4-Dinitrophenol, DNP)-IgE sensitization and DNP-human serum albumin (human serum albumin, HSA) stimulation. The degranulation model is mainly established using rat basophil cell line RBL-2H3 and mouse bone marrow derived mast cells (bone marrow derived mast cells, BMMCs). Five groups are set up, the negative control group is intervened with PBS, the model group is sensitized with anti-DNP-IgE and stimulated with DNP-HSA, the positive drug control group is intervened with dexamethasone, and the polypeptide intervention group is intervened with different doses of polypeptide to analyze the effect of FcεRⅠα specific binding polypeptide on the release of β-hexosaminidase (β-hex). The results show that FcεRⅠα specific binding polypeptide can inhibit mast cell activation and degranulation to a certain extent, and is dose-dependent and has no cytotoxicity.

[0023] In the present invention, comprehensive in vivo and in vitro experiments preliminarily demonstrate that the FcεRⅠα-specific binding polypeptide can inhibit IgE-mediated mast cell-dependent allergic reactions to a certain extent, suggesting that it has a certain inhibitory effect on IgE-mediated type I hypersensitivity reactions, laying the foundation for further research and development of new biological targeted drugs for the treatment of allergic diseases.

[0024] In a second aspect, the present invention provides a nucleic acid molecule encoding the specific binding polypeptide targeting the cell membrane receptor FcεRIα as described in the first aspect.

[0025] In a third aspect, the present invention provides an expression vector comprising the nucleic acid molecule described in the second aspect.

[0026] In a fourth aspect, the present invention provides a host cell, wherein the host cell contains at least one copy of the expression vector described in the third aspect, or the nucleic acid molecule described in the second aspect is integrated into the genome of the host cell.

[0027] In a fifth aspect, the present invention provides a pharmaceutical composition comprising the specific binding polypeptide targeting the cell membrane receptor FcεRIα as described in the first aspect.

[0028] Preferably, the pharmaceutical composition further comprises a pharmaceutically acceptable excipient.

[0029] In the present invention, the term "pharmaceutically acceptable" means that the compound or composition is chemically and / or toxicologically compatible with other ingredients constituting the formulation and / or with humans or mammals for preventing or treating diseases or conditions.

[0030] In a sixth aspect, the present invention provides use of the specific binding polypeptide targeting the cell membrane receptor FcεRIα described in the first aspect in the preparation of a drug for improving inflammatory reactions and allergic symptoms.

[0031] In a seventh aspect, the present invention provides use of the specific binding polypeptide targeting the cell membrane receptor FcεRIα described in the first aspect in the preparation of a drug for inhibiting IgE-mediated mast cell-dependent allergic reactions.

[0032] In an eighth aspect, the present invention provides the use of the specific binding polypeptide targeting the cell membrane receptor FcεRIα described in the first aspect, the nucleic acid molecule described in the second aspect, the expression vector described in the third aspect, or the host cell described in the fourth aspect in the preparation of a drug for the targeted treatment of allergic diseases.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The polypeptide screened and obtained by the present invention has good affinity with the α site of FcεRI and can effectively reduce type I allergic inflammation, which provides a new idea for the targeted treatment of allergic diseases. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Flowchart for screening FcεRIα-specific binding peptides from phage-displayed peptide libraries.

[0036] Figure 2 This is the result of identifying polypeptides that specifically bind to FcεRIα.

[0037] Figure 3 The results of ear thickness changes before and after modeling in each group of mice.

[0038] Figure 4 These are the skin lesion results of mice in each group after modeling.

[0039] Figure 5 Figure 3 Toluidine blue staining and mast cell infiltration results of ear lesions in mice in each group.

[0040] Figure 6 Figure 3 HE staining and inflammatory cell infiltration results of ear lesions in mice in each group.

[0041] Figure 7 The results show the effect of FcεRIα-specific binding peptides on mast cell activity.

[0042] Figure 8 The results show the effect of FcεRIα-specific binding peptides on the β-hexosaminidase release rate of RBL-2H3 cells.

[0043] Figure 9 The results show the effect of FcεRIα-specific binding peptides on the β-hexosaminidase release rate of BMMC cells. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0045] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0046] The sources of experimental materials in the following specific embodiments are as follows:

[0047] OVA: Sigma-Aldrich, A5503.

[0048] Anti-DNP-IgE: Sigma-Aldrich, D8406.

[0049] DNP-HAS: Sigma-Aldrich, A6661.

[0050] Dexa: dexamethasone, Meilunbio, MB1434.

[0051] Example 1

[0052] Screening and identification of FcεRIα-specific phage clones

[0053] Using FcεRIα receptor protein as the target molecule, the phage display peptide library constructed in the early stage was used to screen FcεRIα specific binding phage clones through multiple rounds of "adsorption-elution-amplification" (the specific preparation process is shown in Figure 1 ). The microwells were coated with 0.5 μg / well 5 μL of FcεRIα receptor protein as the target molecule, blocked with BSA, washed 3 times with PBS, incubated with the phage-displayed peptide library at room temperature for 5 hours, washed 20 times with PBST, and incubated with 10 μg / mL of IgE at room temperature for 30 minutes with shaking for competitive elution (competitive elution was added only in the third round), and then amplified with Escherichia coli host bacteria ER2738. Finally, phages with specific binding activity to the target molecule were enriched and amplified to obtain phage polypeptides that specifically bind to the FcεRIα receptor. 20 clones were picked for amplification and their specific binding activity to the FcεRIα receptor protein was measured.

[0054] By randomly selecting 20 phage plaque clones from the eluate after the third round of screening and performing ELISA to detect their specific binding activity to the FcεRIα receptor protein, 11 groups of phages with absorbance close to 3 times or more than that of the control group (original library) were selected as positive clones. The positive clones were sequenced, and finally 6 groups of monoclonal phages with different sequencing were obtained. The positive clones were further subjected to ELISA experiments on the binding of the FcεRIα receptor protein. The results confirmed that the anticalin (peptide molecule) molecules finally screened had good binding affinity with the FcεRIα receptor protein (see Figure 2 ).

[0055] In the figure, (A) absorbance of monoclonal phage peptides and the original random octapeptide library after three rounds of screening; (B) sequencing results of the six monoclonal phage peptides obtained by screening; (C) ELISA detection results of the binding of the six monoclonal phage peptides obtained by screening and the original random octapeptide library to FcεRIα protein; (D) sequence names of the six monoclonal phage peptides and the average absorbance compared with the original random octapeptide library (ns: non-significant; *: P < 0.05; **: P < 0.01; ***: P < 0.001).

[0056] Example 2

[0057] Effects of FcεRIα-specific binding peptides on inflammation in AD mice

[0058] 1. Grouping of mice

[0059] The mice were divided into 10 groups, with 3 mice in each group, including: ① control group (75% ethanol + PBS + PBS), ② model group (calcipotriol + PBS + OVA), ③ library group (calcipotriol + original library + OVA), ④ ketotifen group (calcipotriol + ketotifen + OVA), ⑤ polypeptide A group (calcipotriol + polypeptide A + OVA), ⑥ polypeptide B group (calcipotriol + polypeptide B + OVA), ⑦ polypeptide C group (calcipotriol + polypeptide C + OVA), ⑧ polypeptide D group (calcipotriol + polypeptide D + OVA), ⑨ polypeptide E group (calcipotriol + polypeptide E + OVA), and ⑩ polypeptide F group (calcipotriol + polypeptide F + OVA).

[0060] 2. Operation steps

[0061] According to the above grouping, 1 nmol / L calcipotriol or 14.3 μL of 75% ethanol was applied to both sides of the ears of the mice daily, and after air drying, 5 mg / mL peptide or 5 mg / mL ketotifen or 20 μL of PBS solution was applied. After air drying, 20 g / L OVA stock solution or 25 μL of PBS solution was applied once a day for 12 consecutive days. The ears of the mice were photographed before modeling and on the 14th day, and the ear thickness was recorded after measurement with a vernier caliper. The mice were anesthetized by intraperitoneal injection of 2% sodium pentobarbital solution at a dose of 40 mg / kg. After being killed by cervical dislocation on the 14th day, the ears were cut along the base of the auricle and immersed in 4% paraformaldehyde for subsequent preparation of tissue sections for HE staining and toluidine blue staining.

[0062] Figure 3Figure 3 shows the changes in ear thickness before and after modeling in each group of mice. As shown in Figure 3, there was no statistically significant difference in ear thickness before modeling among the groups (P>0.5). After modeling, the ear thickness of mice in all groups except the control group was significantly greater than before modeling (P<0.001), and significantly greater than the control group (P<0.001), indicating that the AD model was successfully established in mice. After modeling, compared with the model group, the ear thickness of mice in the peptide A, B, D, and F groups, as well as the positive drug ketotifen group, was significantly reduced (P<0.05), with the exception of the library group and peptide C and E groups.

[0063] Figure 4 Figure 4 shows the skin lesions in each group of mice after modeling. As shown in Figure 4, on the 14th day after modeling, the model group showed dryness, congestion, edema, desquamation, and significant thickening of the ear skin compared to the control group, indicating that the AD model was successfully established in mice. Furthermore, with the exception of the library group and peptide C and E groups, the severity of skin lesions in the peptide A, B, D, and F groups, as well as the positive drug ketotifen group, was significantly reduced compared to the model group.

[0064] Figure 5 Figure 5 shows the toluidine blue staining and mast cell infiltration of the ear lesions of mice in each group. As shown in Figure 5, the model and library groups showed a large infiltration of inflammatory cells, a significant increase in epidermal thickness, and a significant increase in mast cell infiltration (P < 0.01). Compared with the model group, the ketotifen group and the peptides A, B, D, and F groups showed reduced mast cell infiltration and decreased mast cell counts (P < 0.05). However, there was no significant statistical difference in mast cell count between the model group and the library group, as well as the peptides C and E groups (P > 0.5). This suggests that peptides A, B, D, and F can reduce mast cell infiltration and alleviate local inflammatory stimulation in AD mice.

[0065] Figure 6 HE staining and inflammatory cell infiltration of the ear lesions of mice in each group were shown. Figure 6 shows that compared with the control group, the stratum corneum thickness of the model and library groups increased significantly, the number of inflammatory cells in the tissues increased significantly, and the distribution of inflammatory cells was disordered, showing a subacute dermatitis-like appearance. Eosinophil infiltration was significantly increased. Compared with the model group, the ketotifen group and the peptide A, B, D, and F groups showed reduced eosinophil infiltration and a significant decrease in eosinophil count (P < 0.001). However, there was no significant statistical difference in the number of eosinophils between the model group, the library group, and the peptide C and E groups compared with the model group (P > 0.5), suggesting that peptides A, B, D, and F can reduce the aggregation of eosinophils in AD mice and alleviate local inflammatory stimulation.

[0066] Figure 3 、 Figure 4 、 Figure 5 and Figure 6In the figure, a: control group; b: model group; c: library group; d: ketotifen group; e: polypeptide A group; f: polypeptide B group; g: polypeptide C group; h: polypeptide D group; i: polypeptide E group; j: polypeptide F group.

[0067] The results showed that FcεRIα specific binding peptides A, B, D, and F could alleviate and improve the inflammatory response and allergic symptoms in the ears of AD mice to a certain extent, among which phage peptides A and B had more significant effects and were effective in treating atopic dermatitis mice (see the results). Figure 3-Figure 6 ).

[0068] Example 3

[0069] Effects of FcεRIα-specific binding peptides on mast cell activity and activation

[0070] 1. Mast cell degranulation model processing process

[0071] RBL-2H3 (rat basophilic leukemia) or BMMC (mouse bone marrow-derived mast cells) cells (3×105) were evenly seeded in 6-well plates. Ten hours after seeding, cells were sensitized with anti-DNP-IgE (50 ng / mL) overnight. On the second day, DNP-HSA (100 ng / mL) was added for a half-hour challenge. For the control group, equal volumes of PBS were used for both sensitization and challenge.

[0072] Two mast cell lines, RBL-2H3 and BMMC, established using the aforementioned method, were divided into four groups: a control group (PBS), a model group (anti-DNP-IgE + DNP-HSA), a peptide group (anti-DNP-IgE + peptide + DNP-HSA), and a positive drug group (anti-DNP-IgE + Dexa + DNP-HSA). Three to four replicate wells were set up in each group. All cells, except the control group, were sensitized overnight with anti-DNP-IgE. On the second day, the intervention group was treated with varying concentrations of FcεRIα-specific peptides, while the positive drug group was treated with 10 nM Dexa. After a one-hour incubation, all groups were challenged with DNP-HSA. After 30 minutes, the cell supernatant was collected and the β-hexosaminidase release rate was measured. During the sensitization and challenge phases, the control group received PBS instead of anti-DNP-IgE and DNP-HSA.

[0073] 2. Isolation and Culture of Mouse BMMC

[0074] The femur of the mouse was removed with scissors, and the bone marrow was removed and soaked in culture medium to ensure moistness and maintain cell viability. The culture medium was then aspirated with a syringe to repeatedly rinse the bone marrow. The rinsed culture medium was centrifuged at 1300 rpm for 5 minutes, and the supernatant discarded. The cell pellet was then lysed with 1 mL of red blood cell lysis buffer for 1-2 minutes, and the lysis reaction was terminated by adding 9 mL of PBS. After centrifugation at 1300 rpm for 5 minutes, a relatively clean cell pellet was obtained. The cell pellet was resuspended in prepared RPMI 1640 culture medium. Finally, the cells were filtered through a sieve and plated into six-well plates for adherent culture for one week. The culture medium for BMMCs was supplemented with the growth factors mSCF (10 ng / mL) and mIL-3 (10 ng / mL) to promote mast cell differentiation. The culture medium was changed after approximately 3 days of culture. After one week, adherent cells were discarded and the suspended cells were transferred to a culture flask and cultured for approximately 4 weeks, at which point the BMMCs were essentially differentiated and mature. The purity of the BMMCs was assessed; mast cell purity ≥95% was sufficient for subsequent experiments.

[0075] 3. Determination of mast cell activity

[0076] The CCK8 assay was used to detect the effects of six peptides on RBL-2H3 cell viability. The specific steps are as follows:

[0077] After the cells have grown well, take an appropriate volume of cells and centrifuge at 900 rpm for 3 min, discard the supernatant, add appropriate culture medium and mix thoroughly, draw 10 μL onto a cell counting plate for counting, and dilute with culture medium to 1×10 6 The diluted cells were inoculated into a sterile 96-well plate, with 1×10 cells / mL in each well. 4 The cells were plated in a volume of 100 μL per well and incubated in a cell culture incubator at 37°C for 24 h.

[0078] Dissolve the peptide in sterile water to prepare a 5 mg / mL stock solution. Discard the old culture medium and serially dilute the peptide with culture medium to 50,000 ng / mL, 5,000 ng / mL, 500 ng / mL, 50 ng / mL, 5 ng / mL, 0.5 ng / mL, 0.05 ng / mL, and 0.005 ng / mL. Add the peptide to a 96-well plate and incubate in a cell culture incubator for 1 hour. PBS was used instead of peptide in the control and model groups.

[0079] Remove the 96-well plate and add 10 μL of 5 mg / mL CCK8 solution to each well. Continue to incubate in the incubator for 1 hour. Detect the OD value of each well at a wavelength of 450 nm using a microplate reader. Analyze and process the data to calculate the cell survival rate. The results showed that the six peptides had no effect on mast cell activity (see Figure 7 ).

[0080] 4. Determination of mast cell β-hexosaminidase release

[0081] The mast cell degranulation model was constructed using the same procedures and grouping as previously described. The lysis group was treated with Trixon at a final concentration of 0.1% for 30 minutes, while the experimental group was stimulated with DNP-HSA for 30 minutes. Cell supernatants from each group were reacted with β-hexosaminidase substrate in a 96-well plate in a 37°C incubator for 90 minutes. The reaction was terminated by adding 150 μL of bicarbonate buffer to each well, and the cells were immediately plated and measured at 405 nm using a microplate reader. The OD value of each group divided by the OD value of the lysis group was the amount of β-hexosaminidase released (%).

[0082] Figure 8 The results show the effect of FcεRIα specific binding peptide on the β-hexosaminidase release rate of RBL-2H3 cells. Figure 9 The results show the effect of FcεRIα-specific binding peptides on the β-hexosaminidase release rate of BMMC cells.

[0083] The results showed that FcεRⅠα specific binding peptide could inhibit mast cell activation and degranulation to a certain extent in a dose-dependent manner (see Figure 8 and Figure 9 ).

[0084] In summary, the present invention provides a method for screening specific binding peptides targeting the cell membrane receptor FcεRIα based on phage display technology. The amino acid sequences of the six peptides screened are FPLHFFA, QLKAGSIH, LPWALSLA, TVDSSPPL, WSPLLWVR, and WNFWNLRA, respectively, and are designated as peptides A, B, C, D, E, and F. ELISA experiments, atopic dermatitis mouse models, and in vitro cell models preliminarily validated that the six peptides possess targeted binding activity, lack cell-killing effects, and effectively inhibit allergic reactions. These peptides are expected to be biological agents that target and antagonize the binding of IgE to FcεRIα to prevent and treat allergic diseases, providing new insights into the targeted treatment of allergic diseases.

[0085] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A specific binding polypeptide targeting a cell membrane receptor FcεRIα, characterized in that: The amino acid sequence of the polypeptide comprises: (I) any one of SEQ ID NOs: 1-6; (II) an amino acid sequence that is at least 90% identical to any one of SEQ ID NOs: 1-6 and specifically binds to the cell membrane receptor FcεRIα.

2. The specific binding polypeptide targeting the cell membrane receptor FcεRIα according to claim 1, characterized in that The polypeptide specifically binds to the α site of FcεRI and inhibits IgE-mediated type I hypersensitivity reaction; Preferably, the polypeptide inhibits mast cell activation and degranulation; Preferably, the polypeptide improves inflammatory responses and allergic symptoms.

3. A nucleic acid molecule, characterized in that The nucleic acid molecule encodes the specific binding polypeptide targeting the cell membrane receptor FcεRIα according to claim 1 or 2.

4. An expression vector, characterized in that The expression vector contains the nucleic acid molecule according to claim 3.

5. A host cell, characterized in that The host cell contains at least one copy of the expression vector according to claim 4, or the nucleic acid molecule according to claim 3 is integrated into the genome of the host cell.

6. A pharmaceutical composition, characterized in that The pharmaceutical composition comprises the specific binding polypeptide targeting the cell membrane receptor FcεRIα according to claim 1 or 2.

7. The pharmaceutical composition according to claim 6, characterized in that The pharmaceutical composition further includes pharmaceutically acceptable excipients.

8. Use of the specific binding polypeptide targeting the cell membrane receptor FcεRIα according to claim 1 or 2 in the preparation of a drug for improving inflammatory reactions and allergic symptoms.

9. Use of the specific binding polypeptide targeting the cell membrane receptor FcεRIα according to claim 1 or 2 in the preparation of a drug for inhibiting IgE-mediated mast cell-dependent allergic reaction.

10. Use of the specific binding polypeptide targeting the cell membrane receptor FcεRIα according to claim 1 or 2, the nucleic acid molecule according to claim 3, the expression vector according to claim 4 or the host cell according to claim 5 in the preparation of a drug for the targeted treatment of allergic diseases.

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