F型肉毒毒素单克隆抗体的筛选及评价

研究以筛选得到中和抗体为目的,通过抗体制备的常用手段——杂交瘤技术进行,以F型肉毒毒素受体结合结构域FHc端作为单克隆抗体的筛选抗原。利用现有抗原FHc蛋白辅助佐剂对动物进行免疫,免疫结束后无菌环境中取动物脾细胞,与预先培养的SP2/0细胞融合后HAT选择性培养基筛选得到阳性杂交瘤细胞株,大量培养后通过体内诱生法制备单抗,纯化后对所得鼠源抗体各指标进行评价,结果测得该单抗亚型为IgG1,κ型、经过Protein G柱纯化后抗体纯度可达到98%以上、与FHc端结构域亲和力可达到5.2×10^-8 mol/L、轻重链基因调取后经Igblast tool分析得抗体可变区中轻链及重链CDR3区氨基酸序列为QHIRELTR、ARWLGDYAMDY,采用10倍半数致死量进行攻毒实验可得,该抗体中和效价在200 LD₅₀/mg,当抗体量达到50μg就可以实现完全保护。实验通过细胞融合的方式,在聚乙二醇的化学刺激下,筛得一株阳性杂交瘤细胞株,取细胞上清,以亲和力作为筛选指标,得到了一株针对F型肉毒毒素受体结合结构域FHc端的具有高亲和力和并同时具有中和效果的鼠...     

人C型凝集素受体dectin-1单克隆抗体的制备

目的:克隆获得并原核表达人dectin-1基因的胞外段,以其作为抗原,制备人C型凝集素受体dectin-1的单克隆抗体.方法和结果:利用RT-PCR技术从人的外周血中克隆获得人dectin-1基因,克隆到pCDNA 3.0(+)载体中,获得pCDNA3.0(+)-dectin-1质粒.将dectin-1胞外段[dectin-1(202 bp-744 bp)]克隆到pET28a(+)载体,构建原核表达质粒pET28a(+)-dectin-1(202 bp-744 bp),转到大肠杆菌E.coli BL21 (DE3)中,IPTG诱导目的片段原核表达,得到高效表达的dectin-1(202 bp-744 bp),镍柱亲和层析纯化后免疫BALB/c小鼠,取抗体滴度高的小鼠的脾细胞与小鼠骨髓瘤细胞SP2/0融合,获得1 5株阳性杂交瘤细胞株,利用有限稀释法进行单克隆杂交瘤细胞株的筛选,获得5株单克隆细胞株.用单克隆细胞株制备小鼠腹水模型,经辛酸-硫酸铵沉淀法纯化获得dectin-1的单克隆抗体.经蛋白质印迹法验证,此单克隆抗体能有效地识别人和小鼠的dectin-1蛋白.结论:成功制备获得dectin-1蛋白的特异、高效的单克隆抗体.     

相思子毒素单克隆抗体的制备纯化及鉴定

目的制备相思子毒素单克隆抗体并鉴定其特性。方法以甲醛处理的相思子毒素毒蛋白为抗原免疫BALB/c小鼠;取免疫小鼠的脾细胞与Sp2/0骨髓瘤细胞融合,经间接ELISA法筛选、融合细胞有限稀释法克隆、克隆化杂交瘤细胞株的亚类鉴定等方法筛选出单克隆抗体杂交瘤细胞株,用杂交瘤细胞株诱生小鼠腹水,应用蛋白A亲和层析法进行单抗的纯化,并对单克隆抗体的特异性进行鉴定。结果获得了4株可稳定分泌单克隆抗体的杂交瘤细胞2D3、4E6、1C8和1E5,诱生的腹水效价分别为1∶1×107、1∶1×106、1∶1×105、1∶1×106,亚类鉴定表明2D3为IgG1,其余3株均为IgG2b;特异性鉴定显示它们与多种毒素均无交叉反应,经过亲和层析,获得了纯化的单抗。结论获得了特异性的相思子毒素单克隆抗体,为建立相思子毒素的检测及纯化方法奠定了基础,其中4E6的效价最高,可作为检测相思子毒素的核心试剂。     

重组Exendin-4-胰高血糖素样肽1/IgG4(Fc)融合蛋白的表达和活性研究

目的  构建表达长效胰高血糖素样肽1（glucagon-like peptide 1,GLP-1）受体激动剂重组Exendin-4-GLP-1/IgG4(Fc)融合蛋白的质粒载体,并研究该融合蛋白的活性。方法  将编码Exendin-4-GLP-1/IgG4(Fc)的重组基因插入表达载体pOptiVEC™-TOPO^®来构建重组质粒Exendin-4-GLP-1/IgG4(Fc)-pOptiVEC™-TOPO^®。将构建的重组质粒转染CHO/DG44细胞并收获表达产物后,分别用亲和层析法和免疫印迹法对表达产物进行纯化和检测。通过胰岛素释放实验确认重组融合蛋白对INS-1细胞胰岛素分泌的影响,同时在CD1小鼠中研究该融合蛋白对血糖的调节作用。结果  转染重组质粒的CHO/DG44细胞可成功表达Exendin-4-GLP-1/IgG4(Fc)。蛋白质印迹法检测显示,纯化的表达产物的相对分子质量（M_r）与预期相符（重组融合蛋白单体和二聚体的M_r分别约为35 000和70 000）。胰岛素释放实验表明,在葡萄糖浓度恒定的情况下INS-1细胞分泌的胰岛素量随重组融合蛋白浓度的升高而增加。CD1小鼠实验显示,重组融合蛋白对链脲佐菌素诱导的糖尿病小鼠的血糖具有调节作用,Exendin-4-GLP-1/IgG4(Fc)处理的糖尿病小鼠的血糖明显低于对照糖尿病小鼠（F=3194,P＜0.01）。结论  Exendin-4-GLP-1/IgG4(Fc)具有天然GLP-1的活性,可作为GLP-1受体激动剂用于2型糖尿病的治疗。     

抗汉城病毒荧光单克隆抗体的制备及初步应用

目的 制备抗汉城病毒（Seoul virus,SEOV）荧光单克隆抗体（单抗）,并初步应用于Ⅱ型肾综合征出血热灭活疫苗原液的病毒灭活验证。 方法  以SEOV L-99株灭活病毒原液为免疫原,采用小鼠杂交瘤细胞融合技术,筛选抗SEOV特异性单抗杂交瘤;小鼠体内诱生法制备单抗腹水,蛋白A亲和层析纯化单抗,并以蛋白质印迹法鉴定其特异性;间接ELISA测定单抗效价和相对亲和力;纯化单抗采用搅拌法标记异硫氰酸荧光素,并分别采用直接免疫荧光法与小鼠脑内接种法对Ⅱ型肾综合征出血热灭活疫苗原液进行病毒灭活验证。结果 共筛选出4株特异性抗SEOV L-99株杂交瘤1D5、2E3、3A4及5B7。蛋白质印迹法鉴定4株单抗均与SEOV L-99株核衣壳蛋白发生特异性反应;间接ELISA测定腹水效价为3.13×10^-8~ 1.25×10^-7;相对亲和力顺序为1D5>3A4>2E3>5B7;纯化抗体纯度>95%;异硫氰酸荧光素标记1D5株单抗的结合比率为3.4;直接免疫荧光法与小鼠脑内接种法检测盲传3代的Ⅱ型肾综合征出血热灭活疫苗原液,病毒灭活验证结果一致。结论 成功筛选到高效价特异性抗SEOV单抗,并制备成荧光单抗,可用于Ⅱ型肾综合征出血热灭活疫苗生产工艺中的病毒灭活验证。     

整合素阻断剂AP25单克隆抗体的制备与鉴定

目的 制备整合素阻断剂AP25的单克隆抗体,鉴定其效价和特异性.方法 从抗原免疫BALB/c小鼠分离免疫脾细胞,通过杂交瘤技术将免疫脾细胞与小鼠骨髓瘤细胞SP2/0融合,筛选杂交瘤细胞株并进行扩大培养.采用小鼠体内诱生法制备腹水,进行纯化后得到抗AP25单克隆抗体,用ELISA和Western blot鉴定其效价和特异性.结果 ELISA检测抗AP25单克隆抗体效价可达1∶2×106,Western blot鉴定抗体特异性良好.结论 获得了能够高表达抗AP25单克隆抗体的杂交瘤细胞株;腹水制备抗体,纯化后得到效价高、特异性良好的AP25单克隆抗体.     

抗Ⅱ型单纯疱疹病毒表面抗原gD单克隆抗体的制备及鉴定

制备抗Ⅱ型单纯疱疹病毒(Simplex Herpes VirusⅡ,HSV-2)表面抗原gD的单克隆抗体(mAb)并对其性质进行鉴定。以基因工程重组制备纯化的HSV2-gD为抗原免疫BALB/c小鼠,采用常规融合制备杂交瘤细胞,通过HAT选择培养、有限稀释法获得单克隆细胞株,用间接ELISA法、Western blot方法筛选和鉴定阳性杂交瘤细胞株。获得了4株可稳定分泌抗HSV2-gD抗体的杂交瘤细胞株,分别命名为1A11C6、1A11F10、4C9D5以及4C9E9,抗体的类型均为IgG1,轻链均为κ型,Western blot结果显示各单抗都可以特异性识别HSV2-gD。用杂交瘤细胞注射小鼠制备腹水,腹水内的抗体效价均大于1×10-5,腹水内的抗体经硫酸铵-辛酸分级沉淀和阴离子交换柱纯化,成功制备了纯度超过95%的高特异性抗体,抗体有较好的特异性。为进一步研究HSV2感染和临床上的预防、诊断及治疗提供了有力的工具。     

2型糖尿病患者胰岛素受体胰岛素结合哉基因突变的研究

目的：研究胰岛素受体结合域基因突变与胰岛素受体（INSR）功能异常的关系。方法：采用聚合酶链反应－单链构象多态性（PCR－SSCP）分析法和核酸银染法,对70例2型糖尿病患者INSR结合域基因第2,3,6三个外显子（exon）及部分相邻内含子进行基因突变检测。结果：在对外显子6的检测中发现有9例突变,突变又可分为B,C两种不同的SSCP带型。其中B型7例,C型2例,C型突变经测序结果,与外显子6的3′端毗邻的内含子的第43位A→C突变。在外显子3中发现了2例突变。为同一带,在外显子2中尚未发现突变带型。结论：INSR结合域基因的突变在2糖尿病中出现的频率较低。C型突变对INSR结合域的影响及其在2型糖尿病发病中的作用尚待进一步研究。     

真核表达重组小鼠IL-15/Fc融合蛋白的制备和活性鉴定

目的 制备真核表达小鼠白细胞介素15(IL-15)和IgGγ1 Fc段融合蛋白,并探讨其对抗原特异性CD8+T细胞的作用.方法 运用RT-PCR方法,从B6小鼠脾细胞中分离小鼠IL-15和IgG γ1绞链区-CH2-CH3 Fc cDNA.在IL-15 3'端和Fc 5'端引入BamH I酶切位点,将IL-15和Fc直接连接,构建小鼠IL-15/Fe融合蛋白基因,再连接到真核表达质粒载体pcDNA3.1(a+)上,转化CHO-S细胞表达、纯化后,研究其活性.结果 融合蛋白486 bp的编码由162个氨基酸组成,其中含48个信号肽氨基酸的小鼠IL-15前体蛋白和由681 bp编码227个氨基酸的IgGγ1-CH2-CH3功能区构成;表达蛋白在IL-15信号肽引导下能高效分泌到培养液中,有二聚体和三聚体两种天然结构,单体分子量约50 kDa,能特异性的结合IL-15R并抑制抗原诱导的CD8+T细胞的增殖反应.结论 成功构建了小鼠IL-15/Fc融合蛋白真核表达载体,并在CHO-S细胞中得到高效表达.此融合蛋白具有较高的生物学活性,可有效地抑制抗原特异性CD8+细胞的增殖反应.     

人绒促性素单克隆抗体的制备与分离纯化

目的制备人绒促性素(hCG)单克隆抗体。方法hCG抗原免疫BALB/c小鼠,取其脾细胞与小鼠骨髓瘤细胞SP2/0按5∶1融合,间接ELISA法筛选阳性孔,有限稀释法进行克隆化培养;制备腹水抗体;间接ELISA法测定抗体效价;采用HiTrap rProtein A FF亲和色谱柱纯化抗体。结果得到2株能稳定分泌单克隆抗体的杂交瘤细胞株,细胞培养上清中抗体效价达10-3以上,腹水抗体效价达10-7以上,纯化后的单抗纯度达98%以上,回收率达75%。结论成功获得两株能稳定分泌单克隆抗体的杂交瘤细胞,可用于早孕、肿瘤等诊断的研究。     

Targeting the Fc receptor in autoimmune disease

Introduction: The Fc receptors (FcRs) and their interactions with immunoglobulin and innate immune opsonins, such as C-reactive protein, are key players in humoral and cellular immune responses. As the effector mechanism for some therapeutic monoclonal antibodies, and often a contributor to the pathogenesis and progression of autoimmunity, FcRs are promising targets for treating autoimmune diseases.

Areas covered: This review discusses the nature of different FcRs and the various mechanisms of their involvement in initiating and modulating immunocyte functions and their biological consequences. It describes a range of current strategies in targeting FcRs and manipulating their interaction with specific ligands, while presenting the pros and cons of these approaches. This review also discusses potential new strategies including regulation of FcR expression and receptor crosstalk.

Expert opinion: FcRs are appealing targets in the treatment of inflammatory autoimmune diseases. However, there are still knowledge limitations and technical challenges, the most important being a better understanding of the individual roles of each of the FcRs and enhancement of the specificity in targeting particular cell types and specific FcRs.     

作用于新生儿Fc受体药物递送系统研究进展

新生儿Fc受体(FcRn)最早发现是母体抗体传递给胎儿和新生儿的膜表面蛋白,后来也证明在成人体内也在多器官、多组织中终生表达,其维持着免疫球蛋白G和血清白蛋白在机体中的长循环和动态平衡,在固有免疫和适应性免疫调节中发挥着极为重要的作用。在现代生物制药研究中, FcRn是良好的药物递送靶点,也是目前研究的热点。本文简述了FcRn的基本生物学性质和作用机制,以及目前常用的FcRn的药物载体设计策略,特别是对于延长半衰期、靶向输送、跨生物膜及抗原递呈等多方面的功能应用进行展望。FcRn在不同组织内的分布和生物学功能,为未来基于FcRn的新型药物递送系统研究和免疫治疗方面等提供更广阔的思路。     

Modulation of guinea-pig peritoneal macrophage Fc receptor activity using D-penicillamine

The influence of D-penicillamine and 2,2'-pyridylisatogen tosylate upon guinea-pig peritoneal IgG Fc receptor activity is examined. D-penicillamine pretreatment of guinea-pig peritoneal cells is shown to selectively reduce the specificity of the interaction between 7s-human IgG and the guinea-pig macrophage Fc receptor population. In contrast, the drug did not influence the binding of guinea-pig 7s IgG2 nor the uptake of aggregated heterologous or homologous Immunoglobulin. Both D-penicillamine and 2,2'-pyridylisatogen tosylate are shown to influence particulate immune complex binding to pretreatment peritoneal cells.     

Fc receptor targeting in the treatment of allergy, autoimmune diseases and cancer

Immune activation and inhibitory receptors play an important role in the maintenance of an adequate activation threshold of various cells in our immune system. Analyses of murine models show that the inhibitory Fcreceptor, FcgammaRIIB plays an indispensable role in the suppression of anti-body-mediated allergy and autoimmunity. In contrast, the activating-type Fcreceptors (FcRs) are essential for the development of these diseases, suggesting that regulation of inhibitory or activating FcR is an ideal target as a therapeutic agent. In addition, recent crystal structural analyses of FcR-Ig-Fc fragment complexes provide an effective approach for developing FcR-targeting drugs. This review summarises recent advances of FcR, which were mainly obtained by murine studies, and highlights novel antibodies as possible FcR-targeting therapies for allergy, autoimmune diseases and cancer.     

Radiolabeled IgG antibodies: Impact of various labels on neonatal Fc receptor binding

The number of therapeutic antibodies in research and development as well as their complexity increases from year to year. Novel therapeutic protein formats, such as Fc‐fusions, bispecific, or multivalent antibodies, are currently in preclinical and clinical development. Therefore, the need for biodistribution and imaging studies, eg, with radiolabeled proteins are very high. However, the labeling process or the label itself can have an impact on binding to cellular receptors, eg, to neonatal Fc receptor (FcRn), which can lead to altered PK properties compared with the unlabeled antibody. FcRn affinity chromatography allows the assessment of immunoglobulin G (IgG) samples with respect to their pH‐dependent FcRn interaction. We analyzed IgGs with different types of labels, namely, direct iodination with ¹²⁵I; chelating agents, such as DOTA and DOTAM; and [³H]propionate. Direct radio‐iodination leads to shifts in FcRn column retention time, which might indicate a potentially faster clearance. Furthermore, high conjugation ratios of chelator lower the affinity to FcRn successively and thus may influence the lysosomal degradation of the antibody in endothelial cells. In contrast, IgGs labeled with [³H]propionate did not show any timeshifts in FcRn affinity chromatography. This article is based on the oral presentation at the IIS 2018 Prague and highlights the importance of an affinity chromatography for characterization of potential changes in affinity to FcRn itself or charge and hydrophobicity.     

Effective mast cell degranulating peptide inhibitors of the IgE/Fc epsilonRI receptor interaction

Previous studies with mast cell degranulating (MCD) peptide have shown that peptide [Ala(12)]MCD 8 was an inhibitor of IgE binding to mast cell receptors. In an attempt to produce increased inhibition, analogs were synthesized that maintained the alanine residue in position 12 in the MCD peptide sequence and were further modified at both termini. Analogs modified at the C-terminus were [Ala(12),desLys(21)]MCD 2 and [Ala(12),D-Lys(21)]MCD 4. N-terminus modifications were [desLys(6)-Arg(7)-His(8),Ala(12)]MCD 1, [Ala(6), Ala(12)]MCD 6, and [Val(6),Ala(12)]MCD 7. To assess the role of the Proline(12), analogs [D-Ala(12)]MCD 3 and [Meleu(12)]MCD 5 were also synthesized. The analogs were tested for binding to the IgE receptor in cultured mast cells. Inhibitory activity of IgE-caused degranulation was measured using a beta-hexosaminidase assay. Circular dichroism (CD) and molecular modeling of selected analogs were used to follow possible structural differences among these analogs. All analogs showed binding affinity to the IgE receptor and inhibition of IgE-induced mast cell degranulation at different levels. Differences in inhibition were most likely because of diverse interactions of the analogs with the receptor as inferred by the CD and modeling studies. Based on the results of the beta-hexosaminidase assay, analog [Val(6), Ala(12)]MCD 7 proved to be an excellent inhibitor of IgE-mediated mast cell degranulation.     

The neonatal Fc receptor,FcRn, as a target for drug delivery and therapy

Immunoglobulin G (IgG)-based drugs are arguably the most successful class of protein therapeutics due in part to their remarkably long blood circulation. This arises from IgG interaction with the neonatal Fc receptor, FcRn. FcRn is the central regulator of IgG and albumin homeostasis throughout life and is increasingly being recognized as an important player in autoimmune disease, mucosal immunity, and tumor immune surveillance. Various engineering approaches that hijack or disrupt the FcRn-mediated transport pathway have been devised to develop long-lasting and non-invasive protein therapeutics, protein subunit vaccines, and therapeutics for treatment of autoimmune and infectious disease. In this review, we highlight the diverse biological functions of FcRn, emerging therapeutic opportunities, as well as the associated challenges of targeting FcRn for drug delivery and disease therapy.     

Development of effective antigen delivery carrier to dendritic cells via Fc receptor in cancer immunotherapy

In cancer immunotherapy with dendritic cells (DCs), which are the most potent antigen-presenting cells, it is important that DCs present peptides derived from tumor-associated antigens on major histocompatibility complex (MHC) class I molecules and activate tumor-specific cytotoxic T lymphocytes. However, exogenous antigens are generally presented on MHC class II but not class I molecules. To develop effective immunotherapy for cancer, an antigen delivery carrier that can induce MHC class I presentation of exogenous antigens is necessary. Several strategies to induce DCs to present exogenous antigens on MHC class I molecules have been reported. First, DCs that phagocytosed a particulate form of antigens present peptides derived from the antigens on MHC class I molecules. Second, DCs that incorporated antigens via certain endocytic receptors such as Fc receptors efficiently present peptides on MHC class I molecules. We combined these two strategies and prepared antigen-containing IgG-conjugated liposomes (IgG-liposomes). In this study, we investigated the feasibility of IgG-liposomes as antigen delivery carriers in cancer immunotherapy with DCs. Immunization of mice with DCs that endocytosed ovalbumin (OVA)-containing IgG-liposomes, but not OVA-containing bare liposomes or soluble OVA, completely prevented the growth of OVA-expressing lymphoma cells. These results suggest that IgG-liposomes represent an efficient antigen delivery carrier for DCs in cancer immunotherapy.     

重组人B淋巴细胞刺激因子受体-抗体融合蛋白的肽图分析

目的:建立重组人B淋巴细胞刺激因子受体-抗体融合蛋白(TACI-Fc)的肽图分析方法。方法:将TACI-Fc蛋白用胰蛋白酶酶解、用尿素将蛋白分子变性、用二硫苏糖醇打断二硫键、用碘乙酰胺封闭巯基、用胰蛋白酶再次酶解等方法处理后,采用高效液相色谱分析,色谱柱为Vydac C18(250 mm×4.6 mm,5μm),流动相A液为含0.1%三氟乙酸的水溶液,流动相B液为含0.1%三氟乙酸的乙腈溶液,梯度洗脱,流速为1.0 mL.min-1,检测波长为214 nm。结果:TACI-Fc蛋白被有效酶解,酶解后的各个片段能够很好的分离。结论:本法准确性高,重复性好,是重组人B淋巴细胞刺激因子受体-抗体融合蛋白结构确认的有效方法。