Anti-IL-6 nano antibody, recombinant nano antibody, recombinant vector and application

Abstract

The invention belongs to the technical field of immunology, and particularly relates to an anti-IL-6 nano antibody, a recombinant nano antibody, a recombinant vector and application. The anti-IL-6 nano antibody disclosed by the invention comprises a heavy chain variable region containing CDR1, CDR2 and CDR3, and has the functions of identifying and combining IL-6. The invention also discloses a recombinant nano antibody containing the nano antibody, a recombinant vector and a detection agent, and applications of the nano antibody, the recombinant nano antibody, the recombinant vector and the detection agent in preparation of drugs for treating IL-6 related diseases. The nano antibody, the recombinant nano antibody and the recombinant vector provided by the invention can recognize and combine IL-6, and have a potential effect of treating IL-6-related diseases.

Description

Technical Field

[0001] The present invention belongs to the technical field of immunology, and specifically relates to an anti-IL-6 nanobody, a recombinant nanobody and a recombinant vector and application thereof. Background Art

[0002] IL-6 (interleukin 6, IL-6) is released by many different types of cells, such as macrophages, T cells, and fibroblasts. The hexameric complex composed of IL-6, its receptor (IL-6 receptor, IL-6R) and glycoprotein 130 (glycoprotein 130, gp130) mediates its biological effects and activates intracellular signal transduction pathways on target cells. Its signal transduction pathways are strictly regulated. If IL-6 signal transduction is dysregulated, it will cause chronic inflammation, autoimmune diseases, etc. In the classical pathway, IL-6 binds to its membrane-bound receptor mIL-6R and membrane protein gp130 to form IL-6-IL-6R-gp130 hexamer, triggering downstream signal transduction and gene expression. In the reverse pathway, the IL-6-sIL-6R complex binds to gp130 and initiates intracellular signal transduction. Next, JAK-STAT, RAS-RAF and other pathways are activated, promoting cell proliferation, differentiation, oxidative stress and immune regulation. However, when IL-6 levels increase, due to the ubiquitous presence of gp130, the signal is widely expressed. IL-6 activates signal transducer and activator of transcription 3 (STAT3) through JAK kinases (JAKs). The STAT3 signaling pathway plays an important role in autoimmune diseases, tumor cell proliferation, angiogenesis, and tumor immune escape. Small molecule inhibitors targeting IL-6 / STAT3 will become potential drugs for the treatment of inflammatory diseases and tumors.

[0003] Nanobodies were first reported by Belgian scientists in Nature in 1993. They are a type of naturally light chain-deficient antibody (VHH) present in the peripheral blood of alpacas. In 1995, they were found in cartilaginous fish such as nurse sharks, spotted sharks, and silver sharks. They are the smallest units known to bind to target antigens. VHH has a molecular weight of only 15KD, so it is also called nanobody (Nanobody, Nb). Nanobodies have unique advantages, including small molecular weight, good solubility, strong stability, high affinity, low immunogenicity, good tissue permeability in the body, and can easily pass through blood vessels or tissues to reach the target site. They have great room for development and are widely used. They can be used clinically for tumor treatment and as diagnostic tools.

[0004] To date, two drugs targeting IL-6R (Tocilizumab and Sarilumab) are clinically available for the treatment of autoimmune diseases, including RA. For example, Tocilizumab is a humanized monoclonal antibody (mAb) that was first approved in Japan in 2005 for the treatment of Castleman disease. Subsequently, Tocilizumab was approved by the FDA in 2010 for various indications, including moderately to severely active RA in adults who have an inadequate response to one or more disease-modifying antirheumatic drugs (DMARDs). In contrast to the impressive results of IL-6R inhibitors, the development of RA therapeutics targeting IL-6 remains stagnant.

[0005] At present, there is still a lack of nano antibodies with good specificity for IL-6 in this field. Therefore, it is urgent to develop a new nano antibody against IL-6. Summary of the invention

[0006] The object of the present invention is to provide an anti-IL-6 nanobody, and the nanobody provided by the present invention can specifically recognize the IL-6 antigen and specifically bind to the IL-6 antigen.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides an anti-IL-6 nanobody, which comprises a heavy chain variable region CDR1-CDR3, and the amino acid sequences of the CDR1-CDR3 are shown in SEQ ID NOs.13-15.

[0009] Preferably, the amino acid sequence of the Nanobody is as shown in SEQ ID NO.1.

[0010] The nucleotide sequence encoding the above-mentioned nanobody is shown in SEQ ID NO.2.

[0011] The present invention also provides a recombinant anti-IL-6 nanobody, the amino acid sequence of the recombinant nanobody is shown in SEQ ID NO.3.

[0012] Preferably, the recombinant nanobody comprises the above-mentioned anti-IL-6 nanobody and a His-tag fusion expression gene, and the nucleotide sequence of the His-tag fusion expression gene is shown in SEQ ID NO.23.

[0013] The nucleotide sequence encoding the above-mentioned recombinant nanobody, the nucleotide sequence of the gene of the recombinant nanobody is shown in SEQ ID NO.4.

[0014] The present invention also provides a recombinant vector for expressing anti-IL-6 nanobody, comprising the gene of the above-mentioned recombinant nanobody and an initial vector; the initial vector is a pCZN1 plasmid vector.

[0015] The present invention also provides an IL-6 detection agent, which comprises the above-mentioned nanobody or the above-mentioned recombinant nanobody.

[0016] The present invention also provides the use of the above-mentioned nanobody or the above-mentioned recombinant nanobody in detecting IL-6 in cells or tissues.

[0017] The present invention also provides the use of the above-mentioned nanobody or the above-mentioned recombinant nanobody in the preparation of drugs for treating autoimmune diseases or anti-tumor diseases.

[0018] Beneficial effects of the present invention:

[0019] The anti-IL-6 nanobody 2H3 provided by the present invention is directed against the heavy chain of IL-6, and the anti-IL-6 nanobody 2H3 includes a framework region FR and an antigenic determinant complementary CDR; the recombinant nanobody expressed by fusion of the gene encoding the anti-IL-6 nanobody 2H3 and the His tag gene can specifically recognize the IL-6 antigen, and can be applied to the molecular diagnosis of autoimmune diseases and tumors and the preparation of autoimmune disease and anti-tumor drugs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 This is the first round of DNA electrophoresis of the nanobody. From left to right, the DNA bands in the gel wells are: the first lane is a 2000 bp marker (the band sizes are: 2000, 1000, 750, 500, 250, 100 bp), the second, third and fourth lanes are PCR products, and the bands are about 700-900 bp;

[0022] Figure 2 This is the second round of DNA electrophoresis of the nanobody. The DNA bands in the gel wells from left to right are: the first lane is a 2000 bp marker (band size is the same as above), the second, third, fourth, fifth and sixth lanes are PCR products, and the band is about 450 bp;

[0023] Figure 3 This is the result diagram of colony PCR analysis to identify the insertion rate of the target fragment;

[0024] Figure 4 The schematic diagram of screening specific single positive clones by phage-ELISA method (phage-ELISA): 1 is IL-6 antigen coated on the ELISA plate, 2 is phage supernatant, 3 is mouse anti-M13K07 antibody, 4 is goat anti-mouse IgG (AP) antibody, and 5 is TMB colorimetric solution;

[0025] Figure 5 This is the result of Phage-ELISA identification of phage monoclone;

[0026] Figure 6 The purified anti-IL-6-2H3 nanobody, wherein the left figure is the SDS-PAGE electrophoresis staining diagram of the post-crushing treatment sample, the outflow sample and the elution sample; the right figure is the SDS-PAGE electrophoresis staining diagram of the purified anti-IL-6-2H3 nanobody;

[0027] Figure 7 is the western blot image of anti-IL-6-2H3 nanobody;

[0028] Figure 8 This is the affinity test chart of anti-IL-6-2H3 nanobody and IL-6 antigen (ELISA);

[0029] Fig. 9 This is the affinity determination diagram of anti-IL-6-2H3 nanobody and IL-6 antigen (BLI). DETAILED DESCRIPTION

[0030] The present invention provides an anti-IL-6 nanobody 2H3, the amino acid sequence 2H3-AA of the nanobody is as follows:

[0031] DVQLVESGGGSVQAGGSLRLSCATSGYTFSSVCMGWFRQAPGKEREGV ASIYTYTGATYYADSVKGRFTISQDIVKDTLDLQMNTLKPEDTAMYYCATDS FGGCRANPLSDSEYNSWGQGTQVTVSS. (SEQ ID NO.1)

[0032] In the present invention, the anti-IL-6 nanobody includes a framework region FR and an antigen determinant complementary region CDR; in the present invention, the framework region FR includes FR1, FR2, FR3 and FR4; the specific amino acid sequence is as follows:

[0033] FR1-AA:DVQLVESGGGSVQAGGSLLRLSCATS(SEQ ID NO.5)

[0034] FR2-AA:MGWFRQAPGKEREGVAS(SEQ ID NO.6)

[0035] FR3-AA:YYADSVKGRFTISQDIVKDTLDLQMNTLKPEDTAMYYC(SEQ ID NO.7)

[0036] FR4-AA:WGQGTQVTVSS(SEQ ID NO.8)

[0037] The corresponding nucleotide sequences are as follows:

[0038] FR1: GATGTGCAGCTGGTGGAGTCTGGGGGAGGCTCGGTGCAGGCTG GAGGGTCTTTGAGACTCTCCTGTGCAACCTCT (SEQ ID NO.9)

[0039] FR2:ATGGGCTGGTTTCGCCAGGCTCCAGGGAAGGAGCGCGAGGGG GTCGCATCT(SEQ IDNO.10)

[0040] FR3: TACTATGCCGACTCCGTGAAGGGCCGATTCACCATCTCCCAGGA CATTGTCAAGGACACGCTTGATCTGCAGATGAACACACTGAAACCTGAGG ACACTGCCATGTATTACTGT (SEQ ID NO. 11)

[0041] FR4: TGGGGCCAGGGGACCCAGGTCACTGTCTCCTCA (SEQ ID NO. 12).

[0042] In the present invention, the complementary region CDR of the antigen determinant includes CDR1, CDR2 and CDR3; the specific amino acid sequence is as follows:

[0043] CDR1-AA:GYTFSSVC(SEQ ID NO.13)

[0044] CDR2-AA:IYTYTGAT(SEQ ID NO.14)

[0045] CDR3-AA: ATDSFGGCRANPLSDSEYNS (SEQ ID NO. 15).

[0046] In the present invention, the nucleotide sequences of CDR1, CDR2 and CDR3 are as follows:

[0047] CDR1: GGGTACACCTTCAGTAGCGTCTGC (SEQ ID NO.16)

[0048] CDR2:ATTTATACTTATACTGGTGCCACA SEQ ID NO.17)

[0049] CDR3: GCGACGGATTCCTTCGGAGGCTGCCGGGCGAATCCATTGTCG GATTCTGAATATAACTCC (SEQ ID NO. 18).

[0050] The "variable region" or "variable domain" of an antibody refers to the amino terminal domain of the heavy or light chain of an antibody. The variable domains of the heavy and light chains may be referred to as "VH" and "VL", respectively. These domains are usually the most variable parts of an antibody (relative to other antibodies of the same type) and contain the antigen binding site.

[0051] The term "variable" refers to the situation that certain segments in the variable domain vary widely in the antibody sequence. The variable domain mediates antigen binding and defines the specificity of a particular antibody to its specific antigen. However, the variability is not evenly distributed over all the amino acids spanned by the variable domain. Instead, it is concentrated in three segments called hypervariable regions (HVRs) (in both the light chain and heavy chain variable domains), namely, HCDR1, HCDR2, HCDR3 (heavy chain antibodies can be referred to as CDR1, CDR2, CDR3) of the heavy chain variable region and LCDR1, LCDR2 and LCDR3 of the light chain variable region. The more highly conserved parts of the variable domain are called framework regions (FRs). The variable domains of natural heavy and light chains each contain four FR regions (FR1, FR2, FR3 and FR4), most of which adopt a β-folded conformation, connected by three HVRs that form a loop connection and in some cases form a part of the β-folded structure. The HVR in each chain is held together in close proximity by the FR region and contributes to the formation of the antigen binding site of the antibody together with the HVR of the other chain. Typically, the structure of the light chain variable region is FR1-LCDR1-FR2-LCDR2-FR3-LCDR3-FR4, and the structure of the heavy chain variable region is FR1-HCDR1-FR2-HCDR2-FR3-HCDR3-FR4. The constant domain is not directly involved in the binding of the antibody to the antigen, but exhibits a variety of effector functions, such as the participation of the antibody in antibody-dependent cell-mediated cytotoxicity.

[0052] In the present invention, the anti-IL-6 nanobody is obtained by screening by the following method: constructing a natural camel-derived nanobody phage display library using phage surface display technology, and then screening based on biotinylated IL-6 antigen to obtain IL-6-specific nanobody gene sequences.

[0053] In the present invention, the method for constructing the natural camel-derived heavy chain antibody phage display gene library preferably includes the following steps: 1) extracting total RNA from camel peripheral blood mononuclear cells and reverse transcribing the total RNA to obtain cDNA; 2) performing nested PCR amplification using the cDNA as a template to obtain the variable region fragment of the heavy chain antibody; 3) respectively enzymatically cutting the variable region fragment of the heavy chain antibody and the pCANTAB5E phage vector, and then connecting them to obtain a connection product; 4) transferring the connection product into the competent cell TG1 to obtain a natural camel-derived nanoantibody phage display library.

[0054] In the present invention, total RNA from camel peripheral blood mononuclear cells is extracted, and the total RNA is reverse transcribed to obtain cDNA. The present invention has no special limitation on the method for extracting total RNA from camel peripheral blood mononuclear cells, and the conventional method for extracting total RNA from animal peripheral blood in the art can be used. In the present invention, the reverse transcription is preferably achieved by Thermo Scientific ReverAid First Strand cDNA Synthesis Kits.

[0055] After obtaining the cDNA, the present invention uses the cDNA as a template to perform nested PCR amplification to obtain the variable region fragment of the heavy chain antibody. In the present invention, the nested PCR preferably includes two rounds of PCR; the first round of PCR is used to amplify the fragment between the heavy chain antibody guide peptide and the antibody CH2, and the primer sequence of the first round of PCR is preferably as shown in SEQ ID NO.19 and SEQ ID NO.20; the second round of PCR is used to amplify the fragment between the heavy chain antibody FR1 region and the long and short hinge regions, and the primer sequence of the second round of PCR is preferably as shown in SEQ ID NO.21 and SEQ ID NO.22.

[0056] After obtaining the variable region fragment of the heavy chain antibody, the variable region fragment of the heavy chain antibody and the pCANTAB5E phage vector are respectively digested, and then connected to obtain a connection product. In the present invention, the digestion is preferably double digestion, and the digestion is preferably performed using restriction endonucleases SifI and Not I. In the present invention, the digestion procedure is preferably as follows: digestion at 37°C for 1h; digestion at 50°C for 1h. In the present invention, the connection temperature is preferably 16°C, and the connection time is preferably 4h.

[0057] After obtaining the ligation product, the present invention transfers the ligation product into competent cells to obtain a natural camel-derived nanoantibody phage display library. In the present invention, the competent cell is preferably an Escherichia coli competent cell TG1, and the Escherichia coli competent cell TG1 is preferably homemade by glycerol resuspension method; the transfer method is preferably electrotransformation. In the present invention, the transformation also includes a process of auxiliary phage rescue. The present invention has no special limitation on the process of electrotransformation and auxiliary phage assistance. For detailed steps, please refer to the embodiment.

[0058] The present invention has no particular limitation on the specific steps of screening anti-IL-6 nanobodies using the biotinylated IL-6 antigen, and conventional nanobody screening methods in the art may be used. For detailed steps, please refer to the examples.

[0059] The present invention also provides a gene encoding the nanobody, and the nucleotide sequence of the 2H3 gene is shown in SEQ ID NO.2, which is as follows:

[0060] GATGTGCAGCTGGTGGAGTCTGGGGGAGGCTCGGTGCAGGCTGGAGGGTCTTTGAGACTCTCCTGTGCAACCTCTGGGTACACCTTCAGTAGCGTCTGCATGGGCTGGTTTCGCCAGGCTCCAGGGAAGGAGCGCGAGGGGGTCGCATCTATTTATACTTATACTGGTGCCACATACTATGCCGACTCCGT GAAGGGCCGATTCACCATCTCCCAGGACATTGTCAAGGACACGCTTGATCTGCAGATGAACACACTGAAACCTGAGGACACTGCCATGTATTACTGTGCGACGGATTCCTTCGGAGGCTGCCGGGCGAATCCATTGTCGGATTCTGAATATAACTCCTGGGGCCAGGGGACCCAGGTCACTGTCTCCTCA.

[0061] The present invention provides a recombinant nanobody against IL-6, comprising the anti-IL-6 nanobody and a His tag fusion expression. In the present invention, the amino acid sequence of the recombinant nanobody (2H3-2AA) is shown in SEQ ID NO.3, specifically as follows:

[0062] HHHHHHMDVQLVESGGGSVQAGGSLRLSCATSGYTFSSVCMGWFRQA PGKEREGVASIYTYTGATYYADSVKGRFTISQDIVKDTLDLQMNTLKPEDTA MYYCATDSFGGCRANPLSDSEYNSWGQGTQVTVSS.

[0063] The present invention also provides a gene encoding the recombinant nanobody, comprising the gene of the nanobody and a His tag fusion expression gene.

[0064] In the present invention, the nucleotide sequence of the gene of the recombinant nanobody (2H3-2) is shown in SEQ ID NO.4, specifically as follows:

[0065] CACCACCACCACCACATGGATGTGCAGCTGGTGGAGTCTGGGGGAGGCTCGGTGCAGGCTGGAGGGTCTTTGAGACTCTCCTGTGCAACCTCTGGGTACACCTTCAGTAGCGTCTGCATGGGCTGGTTTCGCCAGGCTCCAGGGAAGGAGCGCGAGGGGGTCGCATCTATTTATACTTATACTGGTGCCACATACTAT GCCGACTCCGTGAAGGGCCGATTCACCATCTCCCAGGACATTGTCAAGGACACGCTTGATCTGCAGATGAACACACTGAAACCTGAGGACACTGCCATGTATTACTGTGCGACGGATTCCTTCGGAGGCTGCCGGGCGAATCCATTGTCGGATTCTGAATATAACTCCTGGGGCCAGGGGACCCAGGTCACTGTCTCCTCA.

[0066] Among them, the nucleotide sequence of the His tag gene is shown in SEQ ID NO.23, specifically as follows: CACCACCACCACCACCAC.

[0067] Various antibodies of the present invention can be expressed in other cell lines. Suitable mammalian host cells can be transformed with sequences encoding various antibodies of the present invention. Transformation can be carried out by any known method, for example, including packaging the polynucleotide in a virus (or a viral vector) and transducing the host cell with the virus (or vector). The transformation procedure used depends on the host to be transformed. Methods for introducing heterologous polynucleotides into mammalian cells are well known in the art, including dextran-mediated transfection, calcium phosphate precipitation, polybrene-mediated transfection, protoplast fusion, electroporation, polynucleotide encapsulation in liposomes, and direct microinjection of DNA into the nucleus. Mammalian cell lines that can be used as hosts for expression are well known in the art, including but not limited to a variety of immortalized cell lines available from the American Type Culture Collection (ATCC), including but not limited to Chinese hamster ovary (CHO) cells, HeLa cells, baby hamster kidney (BHK) cells, monkey kidney cells (COS), human hepatocellular carcinoma cells (e.g., HepG2), etc. Particularly preferred cell lines are selected by determining which cell lines have high expression levels and produce antibodies with substantial BCMA binding properties.

[0068] The present invention also provides a recombinant vector for expressing anti-IL-6 nanobody, comprising the gene of the recombinant nanobody and an initial vector.

[0069] In the present invention, the initial vector is preferably a pCZN1 plasmid vector; the insertion site of the gene of the recombinant nanobody is preferably located at the Nco I-Xho I site of the pCZN1 plasmid vector. The present invention has no special restrictions on the preparation method of the recombinant vector, and the conventional recombinant vector preparation method in the art can be used.

[0070] The present invention also provides a recombinant strain expressing an anti-IL-6 nanobody, comprising the recombinant vector and Escherichia coli Arctic Express. In the present invention, the recombinant strain is preferably obtained by transferring the recombinant vector expressing the anti-IL-6 nanobody into the Escherichia coli Arctic Express. The present invention does not specifically limit the specific preparation method of the recombinant strain, and the conventional preparation method of the recombinant strain in the art can be used.

[0071] The present invention provides the use of the anti-IL-6 nanobody, the gene encoding the anti-IL-6 nanobody, the recombinant nanobody, the gene encoding the recombinant nanobody, the recombinant vector, and the recombinant strain in the preparation of autoimmune disease and anti-tumor drugs or tumor diagnostic reagents.

[0072] RNA purification kit was purchased from TIANGEN; restriction endonucleases were purchased from NEB; T4 DNA ligase was purchased from NEB.

[0073] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0074] The production processes, experimental methods or detection methods involved in the embodiments of the present invention, unless otherwise specified, are all conventional methods in the prior art, and their names and / or abbreviations are all conventional names in the field, and are very clear and unambiguous in the relevant application fields. Technical personnel in the field can understand the conventional process steps based on the names and apply the corresponding equipment, and implement them according to conventional conditions or the conditions recommended by the manufacturer.

[0075] The various instruments, equipment, raw materials or reagents used in the embodiments of the present invention are not particularly limited in terms of their sources, and are all conventional products that can be purchased through regular commercial channels, or can be prepared according to conventional methods well known to those skilled in the art.

[0076] Example 1 Construction of a natural camel-derived nanoantibody gene library

[0077] 1. Extract total RNA from camel peripheral blood mononuclear cells. The specific steps are as follows:

[0078] (1) Blood collection from Bactrian camels was performed by professionals. Peripheral blood mononuclear cells of non-immunized camels were separated using Percoll cell separation solution. The separated peripheral blood mononuclear cells were washed three times with PBS and 1 mL of Trizol solution was added.

[0079] (2) Add 0.2 mL of chloroform per 1 mL of Trizol, shake vigorously for 15 seconds, and let stand at room temperature for 3 minutes.

[0080] (3) Centrifuge the sample at 12000 rpm and 4°C for 15 min and transfer the upper layer to a new Eppendorf tube.

[0081] (4) Add an equal volume of isopropanol and place on ice for 20 min.

[0082] (5) Centrifuge the solution at 12,000 rpm and 4°C for 10 min and discard the supernatant.

[0083] (6) Add 1 mL of 75% ethanol prepared with DEPC water to wash the precipitate (add at least 1 mL of ethanol for every 1 mL of Trizol).

[0084] (7) Centrifuge the solution from the previous step at 10,000 rpm for 10 min at 4°C, discard the supernatant, and repeat the previous step for one more wash.

[0085] (8) Centrifuge at 10,000 rpm and 4°C for 10 min, discard the supernatant, and dry for 10-15 minutes.

[0086] (9) Add appropriate amount of ddH2O to dissolve the RNA precipitate, determine the RNA concentration, and store at -80°C.

[0087] The RNA was purified using an RNA purification kit and reverse transcribed using the Thermo Scientific ReverAidFirst Strand cDNASynthesis Kits to obtain cDNA.

[0088] 2. Using cDNA as a template, nested PCR was used to amplify the variable region fragment of the heavy chain antibody;

[0089] First round of PCR:

[0090] F-1: 5'-GTCCTGGCTGCTCTTCTACAAAG-3' (SEQ ID NO. 19)

[0091] R-1: 5'-GGTACGTGCTGTTGAACTGTTCC-3' (SEQ ID NO. 20)

[0092] Table 1 First round PCR reaction system

[0093]

[0094] The reaction conditions for the first round of PCR amplification were: 95°C for 5 min; 95°C for 30 s, 55°C for 30 s, 72°C for 45 s, 32 cycles; 72°C for 10 min.

[0095] The fragment between the heavy chain antibody guide peptide and antibody CH2 was amplified. This pair of primers was used to amplify the vh-CH1-CH2 fragment of 900 bp and the vhh-CH2 fragment of about 700 bp. The results were as follows: Figure 1 As shown, the results showed that the size of the fragment was about 700-900 bp, that is, there were about two electrophoresis bands of the nanobody gene.

[0096] Second round of PCR:

[0097] Using the first round PCR product as template,

[0098] F-2: 5'-TCGCGGCCCAGCCGGCCCAGGTCCAACTGCAGGAGTCTGGG G-3' (SEQ ID NO. 21)

[0099] R-2: 5'-ATAAGAATGCGGCCGCTGAGGAGACGGTGACCTGGGTCCCC-3' (SEQ ID NO. 22)

[0100] Table 2 Second round PCR reaction system

[0101]

[0102] The second round of PCR amplification reaction conditions were: 94℃5min; 94℃30s, 55℃30s, 72℃45s, 25 cycles; 72℃10min. The fragments between the heavy chain antibody FR1 region and the long and short hinge regions (long fragment and short fragment) were used to amplify the camel heavy chain antibody heavy chain variable region vhh fragment of about 400bp from the 700bp vhh-CH2 fragment; the results are shown in Figure 2 As shown, the results showed that the size of the fragment was about 450 bp, that is, the electrophoresis band of the nanobody gene was about 450 bp.

[0103] The pCANTAB5e phage vector and VHH fragment were digested with restriction endonucleases SifI and NotI, and the two fragments were connected with T4 DNA ligase. The specific enzyme digestion system and ligation system are as follows:

[0104] Table 3 Enzyme digestion system

[0105]

[0106] Enzyme digestion conditions: digestion at 37°C for 1 h, then at 50°C for 1 h.

[0107] Table 4 Connection system

[0108]

[0109]

[0110] Ligation conditions: 16°C for 4 h, followed by overnight ligation at 4°C.

[0111] The ligation product was electrotransformed into electrocompetent cells TG1 to construct a natural camel-derived nanoantibody phage display library. After helper phage rescue, the library capacity reached 9.0×10 13 .

[0112] The insertion rate of the library was detected by colony PCR. The primers used were the second round PCR primers, and the annealing temperature was 55°C. The results were as follows: Figure 3 The insertion rate was shown to be above 95% (target fragment insertion rate = number of colonies containing the target fragment / total number of colonies).

[0113] 3. The preparation method of competent cells TG1 is as follows:

[0114] (1) Take out E. coli TG1 glycerol culture from a -80°C freezer, streak it onto a 2×YT solid plate and culture it at 37°C for 10 h. Pick a single colony and inoculate it into 3 mL of 2×YT liquid culture medium and culture it at 37°C with shaking at 200 rpm overnight.

[0115] (2) The next day, the bacterial solution was amplified at a ratio of 1:100 in a conical flask containing 200 mL of 2×YT medium and cultured at 37°C until the OD 600 When the concentration is about 0.4, collect the bacterial solution in a 50mL centrifuge tube, let it stand on ice for 1h, centrifuge at 9000rpm, 4℃ for 10min, discard the supernatant and resuspend the bacterial pellet with the same volume of cold pure water, centrifuge, and repeat once. Then resuspend the bacterial pellet with pre-cooled 10% glycerol and centrifuge. Use 1mL 10% glycerol (pre-cooled pure water) to suspend the bacterial pellet and divide it into pre-cooled 1mL Ep tubes, 100μl per tube, and then immediately transfer to -80℃ refrigerator for storage, which is the competent cell TG1.

[0116] 4. The steps for helper phage rescue are as follows:

[0117] (1) Take 100 μL of the library and inoculate it into 50 mL of 2×YT / Amp / Glu medium. Cultivate at 37°C, 200 rpm, and shake until the OD value reaches the logarithmic phase. 600 About 0.4 to 0.5.

[0118] (2) Add helper phage M13KO7 at a multiplicity of infection of 20:1 to the culture medium, mix well, and incubate at 37°C for 30 min.

[0119] (3) Centrifuge the culture at 9000 rpm for 10 min at room temperature, discard the supernatant to precipitate the cells, resuspend them in 200 mL of 2×YT / Amp / Kana culture medium, and culture them at 37°C, 200 rpm, overnight.

[0120] (4) The culture medium was centrifuged at 9000 rpm for 10 min at 4°C, and the supernatant was taken. 1 / 5 volume of PEG / NaCl was added and the culture medium was allowed to stand at 4°C for 6 h.

[0121] (5) Centrifuge at 9000 rpm for 20 min, discard the supernatant, resuspend the precipitate with PBS (1 mL) to obtain the recombinant phage antibody library, dispense it into 1.5 mL Eppendorf tubes, and store it at 4°C.

[0122] Example 2 Screening of anti-IL-6 nanobodies

[0123] The phage library (1×10 13phage) and 50 μL streptavidin magnetic beads were incubated on a rotating table at room temperature for 1 hour, and the phage antibodies were collected; 500 μL of pre-cut phage antibodies were added to two 1 mL centrifuge tubes that had been blocked with 2% PBSM, and 500 μL of 5 μg biotinylated IL-6 antigen diluted with PBS was added to one centrifuge tube, and 500 μL PBS buffer was added to the other centrifuge tube as a negative control, and incubated on a rotating table at room temperature for 1 hour, and then 50 μL of pre-blocked streptavidin magnetic beads were added, and incubated on a rotating table at room temperature for 30 minutes, and the magnetic beads were collected.

[0124] Wash the beads 7 times with PBST, 2 times with PBSM, and 1 time with PBS. Add Glycine at pH 2.7 for elution and 1 mol / LTris-HCl at pH 9.1 for neutralization. Add the neutralization solution to 5 mL of TG1 (OD 600 is 0.5), phages are produced and purified for the next round of screening. After three rounds of screening, positive clones will be continuously enriched, thereby achieving the purpose of using phage display technology to screen IL-6 specific antibodies in the antibody library.

[0125] Phage-ELISA method to screen specific single positive clones:

[0126] Screening principle diagram Figure 4 As shown, the specific method is as follows:

[0127] First, prepare the VHH phage monoclonal supernatant: randomly pick 180 single colonies from the solid plate after three rounds of screening and inoculate them into a 96-deep-well plate containing 2×YT medium containing 100 μg / mL ampicillin and 2% glucose at 220 rpm. Culture at 37°C overnight, take 50 μL of bacterial solution to a new 96-deep-well plate the next day, add 800 μL of 2×YT medium containing 100 μg / mL ampicillin and 2% glucose to each well, grow to the logarithmic phase, add helper phage M13K07 with a multiplicity of infection of 20:1, infect at 37°C for 30 min, centrifuge at 10000 rpm for 5 min, discard the supernatant, resuspend the bacteria with 800 μL of fresh 2×YT medium containing 100 ug / mL ampicillin and 50 ug / mL kanamycin, culture at 37°C, 220 rpm for 12 h, and the next day, centrifuge the bacterial solution at 10000 rpm for 5 min. The supernatant is the VHH phage monoclonal supernatant.

[0128] Dilute IL-6 antigen to 10 μg / mL with coating solution, add 100 μL to each well, coat overnight at 4°C, and set up negative and positive controls. The next day, wash three times with PBST, block with 2% PBSM at 37°C for 2h, wash three times with PBST, add 200 μL of pre-treated VHH phage monoclonal supernatant, and incubate at 37°C for 1h. Add 1:5000 mouse anti-M13KO7 / HRP secondary antibody diluted with 0.1% PBST, incubate at 37°C for 1h, wash off unbound antibodies, add TMB colorimetric solution, and read the absorbance value at a wavelength of 450nm on an enzyme reader. 96x4 monoclones were selected from the plates after the third and fourth rounds of screening, and the monoclonal supernatants were prepared and identified by phage ELISA (Phage-ELISA). PBS was used as the negative control and M13K07 was used as the positive control. When the OD value ratio of the experimental group to the negative control group was ≥2.1, it was considered a positive clone. 40 monoclonal samples with higher absorbance values ​​were selected for sequencing. When the OD value of the sample well was more than twice the OD value of the control well, it was determined to be a positive control well. The results are as follows Figure 5 , take the positive bacterial solution for gene sequencing.

[0129] Snapegene software was used for sequence analysis and blast comparison, and strains with the same CDR1, CDR2, and CDR3 sequences were considered to be the same clone. Finally, the nanobody sequence shown in the amino acid sequence SEQ ID NO.1 was used for subsequent experiments.

[0130] Example 3 Expression and purification of nanobodies in host bacteria Escherichia coli

[0131] (1) The nanobody sequence obtained by sequencing analysis was subcloned into the pCZN1 plasmid vector and transformed into Escherichia coli Arctic Express. A single clone on the transformation plate was picked and inoculated into a test tube containing 3 mL LB culture medium containing 50 μg / mL Kan, and shaken at 37°C and 220 rpm overnight;

[0132] (2) The next day, the cells were inoculated at a ratio of 1:100 into 30 mL LB culture medium containing 50 μg / mL Kan and shaken at 220 rpm at 37°C until the bacterial OD 600 The pH value was 0.6-0.8, IPTG was added to a final concentration of 0.5 mM, and shaken at 20°C and 220 rpm overnight to induce the expression of the fusion protein;

[0133] (3) Collect the cells and perform ultrasonic disruption to obtain the crude inclusion body protein solution, which is then purified by Ni column affinity to obtain the fusion protein. Figure 6As shown, the purified anti-IL-6 nanoantibody, where the left figure is the SDS-PAGE electrophoresis staining image of the purification process of the anti-IL-6 nanoantibody: wherein lane M is the protein molecule standard, lanes 1-2 are the post-crushing treatment samples and the outflow samples, respectively, and lanes 3-4 are the elution samples; the right figure is the SDS-PAGE electrophoresis staining image of the purified anti-IL-6 nanoantibody, wherein lane M is the protein molecule standard, lane 1 is 0.5 mg / mL BSA as the concentration measurement standard, and lane 2 is the purified anti-IL-6 nanoantibody 2H3.

[0134] Example 4 Specificity verification of anti-IL-6 nanobody 2H3

[0135] Western blot was performed using IL-6 antigen (the primary antibody was purified anti-IL-6 nanobody, and the secondary antibody was anti-mouse His / HRP), such as Figure 7 As shown, it is a western blot diagram of IL-6 antigen: wherein lane M is a protein molecule standard, and lane 1 is an IL-6 antigen. This shows that the anti-IL-6 nanobody provided by the present invention can specifically bind to the IL-6 antigen.

[0136] Example 5 ELISA method to detect the specific binding of IL-6 nanobody 2H3 and IL-6 antigen

[0137] The IL-6 antigen was diluted to 2 μg / mL with ELISA coating solution, and 100 μL was added to each well of a 96-well ELISA plate for coating at 4°C. PBS coating was used as a negative control. The next day, the plate was washed three times with 0.05% PBST, patted dry with absorbent paper, and 300 μL of 5% PBSM was added to each well and blocked at 37°C for 2 hours. After blocking, the plate was washed three times with PBST and patted dry. 100 μL of experimental and control group samples were added to each well, incubated at 37°C for 1 hour, washed three times with PBST, patted dry, and mouse His antibody was diluted with 0.05% PBST at a ratio of 1:5000. 100 μL was added to each well. After incubation at 37°C for 1 hour, the plate was washed and patted dry. The sheep anti-mouse HRP antibody was diluted with 0.05% PBST at a ratio of 1:5000. 100 μL was added to each well. After incubation at 37°C for 1 hour, the plate was washed and patted dry. The test results are as follows: Figure 8 As shown, the anti-IL-6-2H3-Nb nanobody specifically binds to the IL-6 antigen.

[0138] Example 6 Anti-IL-6 Nanobody 2H3 and IL-6 Antigen Specificity Detection

[0139] The affinity of the nanobody was determined by biomembrane interferometry (BLI). The biotinylated humanized IL-6 antigen was bound to the Streptavidin (SA) probe, and 6 nanobody concentration gradients of 1000, 500, 250, 125, 62.5 and 31.25 nmol / L were set. The binding and dissociation of nanoantibodies at each concentration with biotinylated humanized IL-6 antigen were determined using Octet Red96e. The detection data were fitted according to the 1:1 binding model, and the binding and dissociation curves of IL-6 nanoantibodies at each concentration with IL-6 antigen were drawn to calculate the KD value.

[0140] The results are as follows Fig. 9 Display: Its binding constant is 4.184×10 -4 , the dissociation constant is 4.993×10 -3 The calculated equilibrium dissociation constant (KD) value is 1.193×10 -7 , suggesting that the anti-IL-6-2H3 nanoantibody has a strong ability to specifically bind to the IL-6 antigen.

[0141] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An anti-IL-6 nanobody, characterized in that The nanobody comprises heavy chain variable regions CDR1-CDR3, and the amino acid sequences of CDR1-CDR3 are shown in SEQ ID NO.13-15.

2. The nanobody according to claim 1, characterized in that The amino acid sequence of the nanobody is shown in SEQ ID NO.

1.

3. The nucleotide sequence encoding the Nanobody according to claim 2, characterized in that The nucleotide sequence is shown as SEQ ID NO.

2.

4. A recombinant nanobody against IL-6, characterized in that The amino acid sequence of the recombinant nanobody is shown in SEQ ID NO.

3.

5. The recombinant nanobody according to claim 4, characterized in that The recombinant nanobody comprises the anti-IL-6 nanobody according to claim 1 and a His-tag fusion expression gene, and the nucleotide sequence of the His-tag fusion expression gene is shown in SEQ ID NO.

23.

6. The nucleotide sequence encoding the recombinant Nanobody according to claim 4, characterized in that: The nucleotide sequence is shown in SEQ ID NO.

4.

7. A recombinant vector expressing an anti-IL-6 nanobody, characterized in that: The recombinant vector comprises the gene of the recombinant nanobody according to claim 5 and an initial vector; the initial vector is a pCZN1 plasmid vector.

8. An IL-6 detection agent, characterized in that The IL-6 detection agent comprises the nanobody according to claim 1 or the recombinant nanobody according to claim 4.

9. Use of the nanobody according to claim 1 or the recombinant nanobody according to claim 4 in detecting IL-6 in cells or tissues.

10. Use of the nanobody according to claim 1 or the recombinant nanobody according to claim 4 in the preparation of drugs for treating autoimmune diseases or anti-tumor diseases.

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