In this study, we constructed a series of recombinant Fc variants of immunoglobulin G4 (IgG4), screened the fragment crystallizable (Fc) variants with significantly prolonged serum half-lives, and analyzed the relationship between mutation site and half-life, aiming to provide a theoretical basis for the development of IgG4 antibodies and Fc fusion protein-based drugs. Nine gene sites were selected for mutation, and different mutation sites were combined. The variant expression plasmids pET24b-Fc were constructed by molecular cloning and point mutation. The plasmids were transformed into Escherichia coli BL21(DE3) for the expression of different recombinant proteins of Fc. Fc2 and Fc3 variants had slightly lower recombinant protein yields, and the expression of other variants was not affected. The toxicity of different Fc variants was determined by cell counting kit-8 (CCK-8) and calcein acetoxymethyl ester/ propidium iodide (calcein AM/PI) in vitro and enzyme-linked immuno sorbent assay (ELISA) in vivo. The results showed that the recombinant Fc variants had good biocompatibility and safety. Finally, the Fc variants were labeled with fluorescent markers, and the effects of different mutations on their serum half-lives were investigated by in vivo experiments. The Fc5 variant with prolonged serum half-life was successfully screened out, which provided a theoretical and practical basis for the optimal design of IgG4 subtype antibody and Fc fusion protein drugs.
Immunoglobulin G/blood* ; Immunoglobulin Fc Fragments/biosynthesis* ; Half-Life ; Animals ; Escherichia coli/metabolism* ; Humans ; Recombinant Fusion Proteins/biosynthesis* ; Recombinant Proteins/biosynthesis* ; Mice

To investigate a baculovirus insect cell system for expressing an interferon alpha 2b (IFNa2b)/immunoglobulin G-4 (IgG4) Fc fusion protein, which has long-acting antiviral effects. Human IFNa2b and IgG4 Fc cDNAs were generated by molecular cloning and inserted into a baculovirus shuttle vector, which was then transposed into the DH10 Bac strain to form recombinant Bacmid-IFN/Fc. The Bacmid-IFN/Fc was transfected into High five insect cells, and expression of the IFN/Fc fusion protein was detected by Western blotting and its biological activity was assessed by the cytopathic effect inhibition method. The IFNa2b and IgG4 Fc cDNA fragments were successfully amplified by RT-PCR using human peripheral lymphocytes. After cloning into the baculovirus shuttle vector, pFastBac1, and transforming into DH10 Bac competent cells, screening identified positive clones carrying the recombinant Bacmid-IFN/Fc. A Bacmid-IFN/Fc clone was successfully transfected into the High five insect cells and packaged into the baculovirus for expression of the IFN/Fc fusion protein. Western blotting revealed that the fusion protein expression was specific, and yielded a protein of 45 kD in size. The in vitro antiviral activity of the IFN/Fc fusion protein was 580 IU/mL. A novel IFN/Fc fusion protein was successfully generated using a baculovirus insect cell system, which may prove useful for providing future experimental data for development of a new long-acting interferon to treat chronic viral hepatitis.
Animals ; Antiviral Agents ; metabolism ; Baculoviridae ; genetics ; Cell Line ; Cloning, Molecular ; Gene Expression ; Gene Fusion ; Genetic Vectors ; Humans ; Immunoglobulin Fc Fragments ; biosynthesis ; genetics ; Immunoglobulin G ; biosynthesis ; genetics ; Insecta ; Interferon-alpha ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Recombinant Proteins ; biosynthesis ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Transfection

We constructed the eukaryotic expression vector of human IL-35-IgG4 (Fc)-pOptiVEC-TOPO by gene recombination technique and expressed the fusion protein human IL-35-IgG4 (Fc) in CHO/DG44 cells. The two components of the newly discovered cytokine human IL-35, EBI3 and IL-12p35, were amplified by PCR from the cDNA library derived from the KG-I cells after LPS induction. The two PCR-amplified cDNA fragments of human IL-35 were linked by over-lapping PCR and then cloned into the IgG4 (Fc)-pOptiVEC-TOPO vector. The constructed plasmid with the recombinant cDNA IL-35-IgG4 (Fc) was verified by restriction enzyme digestion analysis, PCR and DNA sequencing. The verified plasmid with the recombinant cDNA was transfected into CHO/DG44 cells using Lipofectamine 2000. The success of the transfection was examined and confirmed by RT-PCR. After selection in alpha-MEM (-) medium, the IL-35-Ig G4 (Fc) positive CHO/DG44 clones were chosen and the media from these positive clones were collected to be used to purify the fusion protein. The positive CHO/DG44 clones were further cultured in increasing concentrations of MTX and the expression levels of the fusion protein IL-35-Ig G4 (Fc) were repetitively induced by MTX-induced gene amplification. The IL-35-IgG4 (Fc) fusion protein was purified from the media collected from the positive CHO/DG44 clones by protein G affinity chromatography and then identified by SDS-PAGE and Western blotting. The results showed that one protein band was found to match well with the predicted relative molecular mass of human IL-35-IgG4 (Fc) and this protein could specifically bind to anti-human IgG4 (Fc) monoclonal antibody. In conclusion, our study successfully established an IL-35-IgG4 (Fc) positive DG44 cell line which could stably express IL-35-IgG4 (Fc) fusion protein.
Animals ; CHO Cells ; Cricetinae ; Cricetulus ; Gene Fusion ; genetics ; Genetic Vectors ; Humans ; Immunoglobulin Fc Fragments ; biosynthesis ; genetics ; Immunoglobulin G ; biosynthesis ; genetics ; Interleukins ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Transfection

We studied the aggregation of a recombinant engineering antibody (chA21). Anti-ErbB2 antibody chA21 was produced by fusing single-chain Fv (scFv) with human IgG1 Fc fragment, and it was proved to be a drug candidate for cancer therapy. We characterized the aggregation of chA21 by high performance sized-exclusive chromatography (HPSEC), dynamic light scattering (DLS), SDS-PAGE, indirect ELISA assay, and compared the influence of temperature and additive on the level of aggregation and binding activity. Conformation changes of different levels of aggregation were also analyzed via circular dichroism (CD). Finally, we analyzed which part of chA21 was involved in aggregation by cleaving it into scFv and Fc fragments. The results showed that chA21 could form aggregates in the storage solution. The aggregates interacted through non-covalent bonds and remained binding activity. Temperature and additive could slightly affect the level of aggregation and binding activity, while the conformations of chA21 were stable. Aggregation propensity of scFv fragment was almost same as chA21, indicating that scFv may be the major part to form the aggregates. The research on aggregation may be helpful to develop a suitable formulation for chA21 clinical application as well as provide direction for future antibody design and reconstruction.
Antibodies ; chemistry ; metabolism ; Humans ; Immunoglobulin Fc Fragments ; chemistry ; metabolism ; Immunoglobulin Variable Region ; chemistry ; metabolism ; Protein Conformation ; Protein Engineering ; methods ; Receptor Aggregation ; immunology ; Receptor, ErbB-2 ; chemistry ; immunology ; Recombinant Proteins ; biosynthesis ; chemistry ; genetics ; immunology

To prolong serum half-life of human Erythropoietin for better efficacy, a new form of recombinant human erythropoietin (rhEpo-L-Fc) was generated by fusion of a full length human erythropoietin gene and the Fc fragment of human IgG1 with flexible linker sequence. The fusion gene rhEPO-L-Fc was constructed by PCR, then inserted into expression vector pOptiVEC-TOPO, and expressed in Chinese Hamster Ovary cells deficient in the DHFR enzyme(CHO-dhfr-). The chimeric protein was purified by Protein A affinity chromatography, showed expected molecular weight and demonstrated a similar bioactivity compared to that of the native recombinant human erythropoietin (rhEPO) in an EPO-dependent cell-based assay. In vivo pharmacokinetic studies showed that the rhEPO-L-Fc had an elimination half-life of 27 h. In vivo efficacy studies showed that a single dose administration of rhEPO-L-Fc in rats increased the reticulocyte number in the peripheral blood significantly. These results demonstrated that the new engineered rhEPO-L-Fc may become alternative therapeutic approach to extend the half-time of rhEPO to treat anemia.
Animals ; CHO Cells ; Cricetinae ; Cricetulus ; Erythropoietin ; chemistry ; genetics ; metabolism ; pharmacokinetics ; Female ; Humans ; Immunoglobulin Fc Fragments ; biosynthesis ; genetics ; Male ; Rats ; Rats, Sprague-Dawley ; Recombinant Fusion Proteins ; biosynthesis ; chemistry ; genetics ; pharmacokinetics ; Recombinant Proteins

Tumour necrosis factor (TNF-a) is a pro-inflammatory cytokine that has been implicated in many aspects of the airway pathology in asthma, and which has recently been highlighted as potentially important in refractory asthma. To study the feasibility of local treatment of asthma with recombinant adenovirus vector carrying soluble extra-cellular region of TNF receptor I-IgGFc (sTNFRI-IgGFc) fusion protein, The sTNFRI-IgGFc gene was subcloned into the adenovirus shuttle plasmid pDC316, the products were co-transfected into HEK293 cell line with helper plasmid pBHGloxDeltaE1,3Cre. The recombinant adenovirus (Ad-sTNFRI-IgGFc) was produced by homologous recombination of above 2 plasmids in HEK293 cells. After identification with PCR, Ad-sTNFRI-IgGFc was amplified and purified, its titer was measured by TCID50 assay. The transcription and expression of sTNFRI-IgGFc gene in transfected human airway smooth muscle cells (HASMCs) was detected by RT-PCR, ELISA and immunological histochemistry. The anti-TNF activity assay of transfected HASMCs culture supernatant was measured by MTT. Ad-sTNFRI-IgGFc was successfully constructed with the titer of 3x10(10) TCID50/mL. Ad-sTNFRI-IgGFc can transfect HASMC with high efficacy. The transcription of sTNFRI-IgGFc mRNA and the expression of protein were confirmed in the transfected HASMCs. Moreover, the product in 100 microL expression supernatant could completely antagonize the cytolytic effect of 2ng TNFa on L929 cells, even at 1/64 dilution. This study forms the basement of the experiment study on local treatment of asthma with adenovirus expressing sTNFRI-IgGFc.
Adenoviridae ; genetics ; metabolism ; Asthma ; therapy ; Bronchi ; cytology ; Cells, Cultured ; Genetic Vectors ; genetics ; Humans ; Immunoglobulin Fc Fragments ; biosynthesis ; genetics ; Immunoglobulin G ; biosynthesis ; genetics ; Myocytes, Smooth Muscle ; cytology ; metabolism ; Receptors, Tumor Necrosis Factor ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; pharmacology ; Transfection ; Tumor Necrosis Factor-alpha ; antagonists & inhibitors

OBJECTIVETo construct a recombinant adenovirus vector carrying soluble extracellular region of tumor necrosis factor alpha receptor I-IgGFc (sTNFRI-IgGFc) and express the fusion protein in human bronchial epithelial HBE135-E6E7 cells.

METHODSsTNFRI-IgGFc fusion gene was subcloned into the adenovirus shuttle plasmid pDC316, which was co-transfected with helper plasmid pBHGloxPE1,3Cre into HEK293 cells. The recombinant adenovirus (Ad-sTNFRI-IgGFc) was generated by homologous recombination of the 2 plasmids in HEK293 cells. After identification with PCR, Ad-sTNFRI-IgGFc was amplified and purified, and its titer measured using TCID50 assay. The transcription and expression of sTNFRI-IgGFc gene in the transfected HBE135-E6E7 were detected by RT-PCR and immunohistochemistry.

RESULTSAd-sTNFRI-IgGFc was successfully constructed with a viral titer of 3 x 10(10) TCID50/ml. The expression of sTNFRI-IgGFc mRNA and protein was confirmed in the transfected HBE135-E6E7 cells.

CONCLUSIONThe constructed Ad-sTNFRI-IgGFc can effectively infect HBE135-E6E7 cells for efficient expression of sTNFRI-IgGFc protein, which antagonizes the cytolytic effect of TNFalpha in L929 cells, suggesting the potential of adenovirus expressing sTNFRI-IgGFc for local treatment of asthma.

Adenoviridae ; genetics ; Bronchi ; cytology ; Epithelial Cells ; cytology ; metabolism ; Genetic Vectors ; genetics ; Immunoglobulin Fc Fragments ; biosynthesis ; genetics ; Immunoglobulin G ; biosynthesis ; genetics ; Receptors, Tumor Necrosis Factor, Type I ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Transfection

In order to construct a pichia pastoris expression vector containing the extracellular domain of human Jagged1 and the Fc fragment of human IgG1 fusion gene, or containing only the Fc fragment of human IgG1 and to express them in pichia pastoris. The extracellular domain of human Jagged1 gene was cloned from normal human bone marrow cells. After DNA sequencing, the extracellular domain of Jagged1 gene was inserted into pIC-Fc vector constructed previously, which is Pichia pastoris expression vector containing only the Fc fragment of human IgG1. The constructed plasmid was transformed into yeast GS115 by means of electroporation. The recombinant transformants with a high copy number of the plasmid were selected on MD plate with G418. The expression of protein was induced by addition of methanol. Then, protein expression was analyzed by SDS-PAGE. The results indicated that the extracellular domain of human Jagged1 gene was effectively amplified. The DNA sequencing result showed that the constructed plasmid containing hJagged1(ext)-Fc fusion gene was the same as designed. The fusion protein was successfully expressed in Pichia pastoris. It is concluded that the hJagged1(ext) gene has been successfully cloned and expressed, which provides a new fusion protein for further experiments, the hJagged1(ext)-Fc fusion protein can be used as a new stimulator for proliferation of hematopoietic stem/progenitor cells in vitro.
Calcium-Binding Proteins ; biosynthesis ; genetics ; Genetic Vectors ; genetics ; Humans ; Immunoglobulin Fc Fragments ; biosynthesis ; genetics ; Immunoglobulin G ; biosynthesis ; genetics ; Intercellular Signaling Peptides and Proteins ; biosynthesis ; genetics ; Jagged-1 Protein ; Membrane Proteins ; biosynthesis ; genetics ; Pichia ; genetics ; metabolism ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Serrate-Jagged Proteins ; Transfection

Asthma was induced by the sensitization and challenge with ovalbumin (OVA) in mice. B-cell activating factor (BAFF) plays a role in mature B cell generation and maintenance. Here, we investigated whether, BAFF expression was changed in OVA-induced mice and whether the control of BAFF expression level alleviates the symptom of bronchial asthma. BAFF expression was detected in alveolar-associated cells surrounding bronchi of OVA-induced mouse lung tissues. BAFF protein was also increased in OVA-induced mouse serum. The increased BAFF transcripts was detected in OVA-induced mouse splenocytes. OVA-induced asthma was associated with the increased number of eosinophils in bronchoalveolar lavage fluid (BALF). When TACI:Fc scavenging soluble BAFF was injected to OVA-induced mice, a significant inhibition was detected in the thickness of airway smooth muscle and glycol-containing cellular elements in airway that were visualized by hematoxylin/eosin Y and periodic acid-Schiff staining, respectively. In addition, when mice were treated with TACI:Fc protein, BAFF protein level was decreased in alveolar-associated cells surrounding bronchi of OVA-induced mouse lung tissues compared to control mice. When compared to OVA-induced control, TACI:Fc treatment reduced the percentage of non-lymphoid cells and no changes were detected in lymphoid cell population. Hypodiploid cell formation in BALF was decreased by OVA-challenge but it was recovered by TACI:Fc treatment. Collectively, data suggest that asthmatic symptom could be alleviated by scavenging BAFF and then BAFF could be a novel target for the develpoment of anti-asthmatic agents.
Animals ; Apoptosis ; Asthma/chemically induced/*drug therapy/immunology ; B-Cell Activating Factor/*biosynthesis ; Bronchi/metabolism/pathology ; Bronchoalveolar Lavage Fluid/cytology ; Eosinophils/pathology ; Female ; Humans ; Immunoglobulin Fc Fragments/*genetics ; Immunoglobulin G/*genetics ; Lymphocytes/pathology ; Mice ; Mice, Inbred BALB C ; *Ovalbumin ; Pulmonary Alveoli/metabolism ; Recombinant Fusion Proteins/genetics/*therapeutic use ; Spleen/metabolism ; Transmembrane Activator and CAML Interactor Protein/*genetics

OBJECTIVE: To evaluate the expression of hCTLA4-Ig and their biological function in newborn porcine islets (NPIs) transfected with AAV-hCTLA4-Ig. METHODS: Cultured NPIs were transfected with AAV-hCTLA4-Ig. The expression of CTLA4-Ig in these NPIs was assayed by RT-PCR and immunocytochemistry. The levels of IL-2, IFN-gamma, and TNF-alpha in the culture medium were assayed by ELISA after these cells the co-cultured with human. The response of glucose-stimulated insulin secretion was observed in the transgene group and the control group. RESULTS: The expressions of CTLA4-Ig mRNA and protein were detected in the transgene group. The levels of cytokines were obviously lower in the transgene group than those in the control group (P<0.01). There was no significant difference in the response of glucose-stimulated insulin release between the transgene group and the control group (P>0.05). CONCLUSION AAV mediated hCTLA4-Ig expression in NPIs could inhibit T lymphocyte to produce cytokines, while the endocrine functions of the NPIs were not significantly affected.
Animals ; Animals, Newborn ; Antigens, CD ; biosynthesis ; genetics ; Antigens, Differentiation ; biosynthesis ; genetics ; CTLA-4 Antigen ; Cells, Cultured ; Dependovirus ; genetics ; Enzyme-Linked Immunosorbent Assay ; Gene Expression ; Humans ; Immunoglobulin Fc Fragments ; biosynthesis ; genetics ; Immunohistochemistry ; Interferon-gamma ; analysis ; Interleukin-2 ; analysis ; Islets of Langerhans ; cytology ; immunology ; metabolism ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Swine ; Transfection ; Tumor Necrosis Factor-alpha ; analysis