PD-L1重组蛋白的表达及生物学活性分析

目的 构建细胞程序死亡因子1配体1(PD-L1)的重组表达质粒,在原核系统中表达并分析其生物学活性.方法 经密码子优化后合成PD-L1全基因序列,构建硫氧还原蛋白-pET43b/(PD-L1)重组表达质粒并在大肠埃希菌中表达;用ELISA验证表达产物与其受体结合的生物学活性.结果 正确构建了PD-L1重组表达质粒及其大肠埃菌基因工程菌,能稳定、高效地表达目的 蛋白,相对分子质量为47×103,目的 蛋白能与其受体特异性结合.结论 成功获得有生物学活性的PD-L1重组蛋白,为研制单克隆抗体及其与病毒感染慢性化的关系提供基础条件.     

人sPD-1-Fc融合蛋白的构建及Cos-7细胞的表达

目的:构建重组人pSG5-Fc-hPD-1嵌合基因质粒,并在真核细胞进行表达,得到分泌性的sPD-1-Fc融合蛋白。为PD-1的生物学活性研究奠定基础。方法:从GenBank里查到人PD-1胞外区的基因序列,设计特异性引物,以人淋巴细胞cDNA为模板PCR扩增得到人PD-1胞外区片段。以pSG5-Fc真核表达质粒为载体,构建得到重组质粒pSG5-Fc-hPD-1。脂质体瞬时转染猴肾成纤维细胞(Cos-7),收取72 h的细胞上清。用Western blot鉴定,并与原核表达的人PD-L1蛋白免疫共沉淀检测生物学活性。结果:通过EcoRⅠ/BamHⅠ双酶切及测序证实构建的重组质粒pSG5-Fc-hPD-1正确。重组质粒在Cos-7细胞中高效表达并分泌融合蛋白sPD-1-Fc到细胞上清,应用Western blot测定到上清中的融合蛋白,且得到的sPD-1-Fc融合蛋白具有与PD-L1结合的生物学活性。结论:通过基因重组方法在真核细胞里得到高效分泌型表达的sPD-1-Fc重组蛋白,为研究PD-1生物学活性奠定了实验基础。     

人PD-1Δex3基因的克隆、表达及其生物学活性的鉴定

目的:构建表达人PD-1Δex3(ΔPD-1)基因的真核表达载体,检测其表达和生物学活性。方法:通过RT-PCR的方法获得人PD-1全长(PD-1)基因,设计特异性引物,PCR方法获得PD-1Δex3基因的2个cDNA片段,通过重组PCR的方法获得ΔPD-1基因,将目的片段双酶切后与pIRES2-EGFP真核表达载体连接,构建重组真核表达载体pIRES2-EGFP/PD-1和pIRES2-EGFP/ΔPD-1并进行鉴定;脂质体转染法将重组载体导入293T细胞;流式细胞术(FCM)检测转染细胞膜表面PD-1的表达;Western blot法检测培养上清中可溶性PD-1(sPD-1)的表达;间接免疫荧光实验分析ΔPD-1蛋白与PD-1两个配体PD-L1和PD-L2的结合。结果:酶切和测序结果均证实插入的基因序列正确,成功构建两个真核表达载体;FCM分析和Western blot检测结果表明,PD-1转染细胞膜表面高表达PD-1蛋白,细胞培养上清中无sPD-1蛋白,而ΔPD-1转染细胞膜表面不表达PD-1蛋白,细胞培养上清中则有大量sPD-1;间接免疫荧光实验结果表明,ΔPD-1蛋白能够与PD-1两种配体产生特异性结合。结论:成功进行PD-1Δex3基因的真核表达,证实PD-1Δex3基因编码sPD-1蛋白,该蛋白具有良好的生物学活性,为进一步研究PD-1Δex3在PD-1/PD-L信号通路中的生物学作用提供了有价值的物质基础。     

抗PD-L1 单抗的研制及其对乙型肝炎病毒的抑制效果初步研究

目的:获得具有阻断PD-1/ PD-L1 结合活性的Anti-PD-L1 单克隆抗体,并在体内和体外模型中初步探索其应用于慢性HBV 感染治疗的潜力。方法:利用大肠杆菌原核表达系统和离子交换柱层析纯化手段,表达纯化获得具有体外结合活性的人源和鼠源的PD鄄1/ PD-L1 蛋白,采用纯化后的人PD-L1 蛋白作为免疫原免疫BALB/ c 小鼠,制备小鼠抗人PD-L1 的单克隆抗体杂交瘤细胞株,基于间接化学发光免疫法评估了这些抗体与人源和鼠源重组蛋白的结合活性,并定量评估它们对PD-L1 体外相互作用的阻断活性。利用慢乙肝病人PBMC 体外刺激方法评估其对T 细胞功能的促进作用,在HBV 转基因小鼠中评估其抑制HBV 的效果。结果:本研究获得了8 株稳定分泌Anti-PD-L1 的单克隆抗体杂交瘤细胞株,其中Anti-PD-L1Ab5 和Ab6 两株单抗与人和小鼠的PD-L1 具有较强的交叉反应性,且均可阻断人和小鼠的PD-1/ PD-L1 结合活性。在慢乙肝病人PBMC 刺激培养实验中,Ab5 和Ab6 可促进酌干扰素水平升高;在HBV 转基因小鼠中单剂注射Ab6,48 h 后血清HBVDNA 水平降低20 倍,血清HBsAg 水平降低至基线水平的30%。结论:获得了2 株具有阻断人和小鼠PD-1/ PD-L1 结合活性的单克隆抗体,其在PBMC 体外刺激培养系统中可促进慢乙肝病人的T 细胞功能,在HBV 转基因小鼠中具有显著的抗病毒效果,具备一定的治疗应用潜力。     

小鼠PD-1胞外段的克隆、原核表达及活性分析

目的小鼠PD-1胞外段(ePD-1)原核表达载体的构建、表达、纯化及其生物学效应初步研究。方法应用小鼠脾细胞总RNA,采用RT-PCR克隆PD-1胞外段基因,将其重组到原核表达载体pGEX-4T-1中,构建原核表达载体pGEX-4T-1-ePD-1,转化至E.coli DH5α,筛选阳性菌落,进行酶切及测序鉴定。将测序正确的重组表达质粒pGEX-4T-1-ePD-1转化至E.coli BL21(DE3)中,经IPTG诱导表达后,对表达产物进行SDS-PAGE和Western blot检测,同时通过蛋白质纯化仪纯化GST-ePD-1融合蛋白。利用流式细胞术和Alamar Blue法,检测纯化的PD-1胞外段融合蛋白对淋巴细胞增殖的影响,评价其生物学活性。结果成功构建重组质粒pGEX-4T-1-ePD-1,并在E.coli BL21(DE3)中获得了成功表达,利用蛋白质纯化仪得到纯化的GST-ePD-1融合蛋白。流式细胞术和Alamar Blue法结果均显示,不同浓度的融合蛋白作用于混合淋巴细胞,与阴性对照相比,可明显促进淋巴细胞的增殖。结论成功地克隆、表达和纯化了小鼠ePD-1蛋白,纯化的重组蛋白可有效促进淋巴...     

TRAIL和EGFR配体寡肽与力达霉素辅基蛋白融合蛋白制备过程的优化

目的对以包涵体形式表达的TRAIL和EGFR配体寡肽与力达霉素辅基蛋白融合蛋白Ec-LDP-TRAIL的制备过程进行优化。方法对大肠杆菌原核表达Ec-LDP-TRAIL目的蛋白的温度、诱导物浓度、起始菌体密度及时间等条件进行优化;在Ni2+亲和层析纯化蛋白过程中对样品预处理以及纯化缓冲液成分进行优化;对纯化后蛋白的分步透析复性过程进行一系列优化,并通过基于ELISA的结合活性实验分析Ec-LDP-TRAIL与肿瘤细胞的结合能力。结果经过工艺优化后,纯化后的融合蛋白Ec-LDP-TRAIL纯度达95%以上,复性后LB培养基活性蛋白收率约为2.2 mg/L,与初始复性条件相比提高近2倍。复性后融合蛋白Ec-LDP-TRAIL显示出能够与人表皮癌A431和人大细胞肺癌H460细胞的结合活性。结论融合蛋白Ec-LDP-TRAIL制备过程的优化为后续研发和生产奠定了实验基础,同时也为其他以包涵体形式表达的基于TRAIL的抗肿瘤蛋白药物的制备提供借鉴。     

小鼠PD-1胞外区基因片段表达、纯化及其多克隆抗体的制备

目的:原核表达并纯化小鼠PD-1膜外区(以下简称mPD-1)蛋白,制备其多克隆抗体。方法:原核表达质粒pGEX-4T-1/mPD-1转化大肠杆菌E.coliBL21(DE3),IPTG诱导重组蛋白的表达。对表达产物进行SDS-PAGE电泳和Western blot检测。利用蛋白质纯化仪纯化蛋白。使用纯化蛋白免疫日本大耳白兔3次后,分离抗血清,ELISA法测定兔多克隆抗体滴度。用其制备的多克隆抗体通过细胞免疫荧光方法(CIF)和FCM检测高表达PD-1全长基因的L929细胞。结果:诱导表达并纯化了GST-mPD-1重组蛋白,得到相对分子质量(Mr)约42000的mPD-1蛋白。纯化蛋白免疫动物后,产生特异的高滴度抗体(ELISA滴度达1∶1562500)。CIF和FCM结果显示抗血清与L929细胞表面PD-1有高度的特异性结合活性。结论:成功获得高纯度的mPD-1重组蛋白,免疫动物后,获得了特异、高效价的抗体,为将mPD-1蛋白及抗体用于PD-1的生物学研究及抗肿瘤治疗的实验研究奠定了基础。     

鼠抗人PD-L1单克隆抗体的研制和生物学活性鉴定

目的 研制鼠抗人PD-L1功能性单克隆抗体,并对其生物学活性进行鉴定.方法 以前期原核表达的人硫氧还原蛋白-（PD-L1）融合蛋白为免疫原免疫BALB/c小鼠,利用杂交瘤技术进行细胞融合,Western-Blot和酶联免疫吸附试验（ELISA）筛选阳性杂交瘤细胞,竞争抑制法ELISA实验鉴定抗体的特异性亲和力,小鼠腹水法作大量抗体制备.结果 获得4株能够稳定分泌特异性抗PD-L1抗体的杂交瘤细胞,经验证所分泌的抗体具有较强的特异性亲和力,经过大量抗体制备和纯化获得效价大于1∶32000的纯化抗体;同时获得1株能稳定分泌抗硫氧还原蛋白抗体的杂交瘤.结论 成功制备了鼠抗人PD-L1单克隆抗体,为下一步应用研究奠定了基础.     

登革病毒1～4型E蛋白结构域Ⅲ融合蛋白的表达纯化及功能研究

目的 了解原核表达的登革病毒（Dengue virus,DV）1～4型融合的E蛋白结构域Ⅲ直接抑制登革病毒感染及其抗体的中和作用.方法 通过连接肽将1～4型登革病毒包膜蛋白Ⅲ区串联的基因产物插入PET30a在大肠埃希菌中进行表达、纯化后,应用Western Blot及间接ELISA验证表达产物.将融合蛋白免疫新西兰大白兔制备免疫血清,应用间接免疫荧光检测多抗血清的活性.将融合蛋白及多抗血清分别进行阻断实验和中和实验,对抗原及抗体的功能进行研究.结果 在大肠埃希菌中成功表达了串联的登革病毒1～4型E蛋白结构域Ⅲ融合蛋白,并得到兔抗免疫血清,分别对融合蛋白及兔抗免疫血清进行验证.融合蛋白能够阻断1～4型DV感染,兔抗免疫血清能中和1～4型DV,但中和抗体效价不同.结论 串联表达的登革病毒包膜蛋白Ⅲ区可抑制登革病毒感染,串联rEⅢ蛋白免疫新西兰大白兔产生的针对DV1～4型包膜蛋白结构域Ⅲ区的抗体对登革病毒具有中和作用.     

小鼠PD-L1胞外段基因的原核表达及活性分析

目的原核表达小鼠程序性死亡分子1配体胞外段(exPD-L1)蛋白基因并在体外初步验证其生物学活性。方法应用小鼠脾脏细胞总RNA,反转录PCR克隆exPD-L1基因序列,将其克隆到pGEX-4T-1载体中构建原核表达载体pGEX-4T-1-exPD-L1,经酶切和测序鉴定正确后,转化到E.coli BL21(D3)中,经IPTG诱导表达后,对包涵体蛋白进行复性和纯化。对表达产物进行SDS-PAGE分析和Western blot法检测证明其正确后,采用GST pull-down检测融合蛋白和PD-1的相互作用,鉴定其生物学活性。结果成功构建重组质粒pGEX-4T-1-exPD-L1,并在宿主菌中成功表达相对分子质量(Mr)55 000的重组蛋白,包涵体成功复性和纯化后经Western blot法证明其正确表达,同程序性死亡分子1(PD-1)蛋白的GST pull-down结果表明融合蛋白具有生物学活性。结论成功克隆和表达小鼠exPD-L1蛋白,并证明其具有生物学活性。     

程序性死亡蛋白配体-1/程序性死亡蛋白-1在老年胃癌患者外周血CD8+T淋巴细胞中的表达及临床意义

目的 通过分析程序性死亡蛋白配体-1/程序性死亡蛋白-1(programmed death ligand-1/programmed death-1,PD-L1/PD-1)在老年胃癌患者外周血CD8+T淋巴细胞中表达情况,探讨其临床意义.方法 选择同一时期90例老年胃癌患者(具有不同临床分期)及90例老年健康体检者,分别采取新鲜外周血后经流式细胞仪检测血中CD8+T淋巴细胞表面PD-L1/PD-1表达情况,结合老年胃癌患者的临床分期,分析PD-L1/PD-1在不同胃癌分期中的表达意义.结果 PD-L1/PD-1在老年胃癌患者外周血CD8+T淋巴细胞呈高表达,相较于老年健康者差异具有统计学意义(t=7.043,P<0.05);外周血CD8+T淋巴细胞的PD-L1/PD-1阳性表达均随着临床分期的增加而增加,呈明显的正相关性(r=0.883,P<0.05);外周血CD8+T淋巴细胞的PD-1阳性表达随着临床分期的增加而增加,两者之间呈正相关性(r=0.811,P<0.05);临床分期较晚的老年胃癌患者外周血CD8+T淋巴细胞PD-L1/PD-1表达比其他相对较早的临床分期老年胃癌患者显著上升(t=4.377,P<0.05).结论 PD-L1/PD-1信号通路异常在老年胃癌患者病变的发生发展过程中发挥了重要作用,外周血CD8+T淋巴细胞PD-L1/PD-1的表达对评判患者的预后具有指导作用.     

MMR deficient undifferentiated/dedifferentiated endometrial carcinomas showing significant programmed death ligand-1 expression (sp 142) with potential therapeutic implications

BackgroundUterine undifferentiated (UEAC)/dedifferentiated (DEAC) carcinomas are rare malignant neoplasms. They appear to pursue an aggressive clinical course with an advanced stage at presentation. Recently, it was discovered that the use of immunotherapeutic drugs targeting programmed cell death protein 1 (PD1)/programmed death ligand-1 (PD-L1) was associated with improved survival in several types of cancer (especially in patients with mismatch-repair (MMR) deficient patients). Whether these findings can be applied to UEAC/DEAC remains a question. Herein, the aim of this study is to evaluate the expression of PD-L1/PD-1 in UEAC/DEAC and its relationship to MMR status. This could offer useful therapeutic information.DesignReview of endometrial carcinoma (EC) diagnosed over the period of 2011 to 2017 in our institution identified 14 UEAC/DEAC cases (n=14). All cases had immunohistochemistry performed for MMR (MLH1, PMS2, MSH2 and MSH6), PD-L1 and PD-1. The protein expression was examined and in DEAC cases both the undifferentiated component and the low grade component were recorded separately. The expression of PD-L1 and PD-1 was scored in both the tumor and the peritumoral lymphocyte infiltration.ResultsOverall variable degrees of tumoral or immune stromal PD-L1 staining (from 1% to 5%), was present in 50.0% (7/14) of UC/DEACs. Seven cases (50%) were PD-1 positive (immune stromal). Five cases (35.7%) showed co-expression of PD-1 and PD-L1 (Figure 1). Worth noting is that PD-1 staining was exclusively present in peritumoral immune cells. Following this the 14 cases were further divided into MMR deficient and MMR proficient groups (Table 1). A total of 8 cases had MMR deficiency (57.1%). There was a statistically significant association for PD-L1 positivity in the MMR deficiency group (p=0.05). However there was no statistically significant differences regarding PD-1 positivity between MMR groups.ConclusionsPD-L1 and PD-1 were expressed in majority of MMR-deficient UEAC /DEAC cases. PD-L1 was not expressed in MMR-proficient carcinomas. These findings might help support potential immunotherapy trials in MMR-deficient UEAC /DEAC.     

Specific and high-affinity binding of tetramerized PD-L1 extracellular domain to PD-1-expressing cells: possible application to enhance T cell function

The negative co-stimulatory receptor, programmed cell death 1 (PD-1), is induced on activated T cells and delivers inhibitory signals upon engagement with its ligands PD-L1 and PD-L2, which are expressed on various somatic cells and certain cancers. Accumulating evidence suggests that interfering with the PD-1-PD-L1 interaction may result in the restoration of defective T cell functions in cancer and chronic viral infection. Herein, we established procedures to produce large amounts of renatured recombinant extracellular domain proteins of mouse PD-1 (mPD-1) and PD-L1. While monomeric mPD-1 and mouse PD-L1 (mPD-L1) only marginally interacted with the cells expressing their counterpart proteins, their tetramerization markedly enhanced the affinity with the K(d) of mPD-L1 tetramer being nearly 100-fold lower than that of the corresponding monomer. The affinity of mPD-L1 tetramer was even higher than a high-affinity anti-PD-1 mAb, and it efficiently inhibited the binding of mPD-L1/Fc-chimeric protein to mPD-1(+) cells. Functionally, mPD-L1 tetramer significantly enhanced the proliferative responses as well as the cytotoxic activity of T cells against specific target cells in vitro. The results suggest that oligomeric PD-L1 extracellular domains may provide a potential means to restore T cell functions in cancer and viral infection in humans.     

PD-L2:PD-1 involvement in T cell proliferation, cytokine production, and integrin-mediated adhesion

The B7 family member programmed death ligand 2 (PD-L2) has been implicated in both positive and negative regulation of T cell activity. In this study, we demonstrate that on human T cells, PD-L2 acts only as a negative regulator of T cell activity, inhibiting proliferation, IL-2 production, and IFN-gamma production via its interaction with programmed death-1 (PD-1). This study also shows a novel role for PD-1 in inhibiting beta1 and beta2 integrin-mediated adhesion. PD-L2 inhibition of T cell function involves modulation of the phosphoinositide 3-OH kinase (PI 3-K)/AKT and extracellular signal-related kinase (ERK)/mitogen-activated protein kinase (MAPK) pathways, with PD-L2 inhibiting anti-CD3-induced AKT phosphorylation within minutes and ERK phosphorylation after hours. Analysis of phosphatase activity of Src homology 2 domain-containing tyrosine phosphatase (SHP)-1 and SHP-2 in response to anti-CD3 mAb or anti-CD3 mAb + PD-L2 stimulation revealed that while SHP-1 phosphatase activity is not affected by stimulation, SHP-2 phosphatase activity is significantly increased by anti-CD3 mAb + PD-L2 stimulation. Anti-CD3 mAb + PD-L2 stimulation also increased the level of SHP-2 associated with the PD-1 receptor. These results suggest that catalytically active SHP-2 associated with the PD-1 receptor is involved in modulating T cell function.     

Clinicopathological value of programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) expression in synovium of patients with rheumatoid arthritis

The etiology of rheumatoid arthritis (RA) is thought to involve dysfunction of the programmed cell death 1/programmed cell death ligand 1 (PD-1/PD-L1) pathway; PD-1 negatively regulates autoimmunity by interacting with its ligand, PD-L1. We therefore investigated PD-1/PD-L1 expression in synovial tissue of patients with RA. We immunohistochemically stained synovial specimens from 51 patients with RA and assessed the association between PD-1/PD-L1 expression and rheumatoid factor (RF), the total count of infiltrating T cells, C-reactive protein (CRP), and Krenn’s synovitis score. PD-1 expression on infiltrating lymphocytes was detected in 34/51 RA cases (66.7%), while PD-1 expression was very mildly correlated only with the number of total infiltrating T cells (R²?=?0.1011, P?=?0.0230). On the other hand, PD-L1 expression on synovial lining cells was observed in 37/51 RA cases (72.5%). Furthermore, a higher PD-L1 expression was significantly associated with RF positive state (P?=?0.0454), and the correlations between PD-L1 expression and the number of infiltrating T cells (R²?=?0.5571, P?<?0.0001), CRP (R²?=?0.4060, P?<?0.0001), and Krenn’s synovitis score (R²?=?0.7785, P?<?0.0001) were confirmed. PD-1 was expressed on infiltrating lymphocytes, while PD-L1 was expressed on synovial lining cells; the expression of PD-L1 on synovial lining cells was significantly correlated with the active state of the disease. These data suggest that PD-1/PD-L1 pathway may have an important role in the pathogenesis of RA.     

抗人PD-L1 单克隆抗体的制备及其应用

目的:获得能应用于临床诊断以及阻断PD-L1 与PD-1 结合的抗人PD-L1 单克隆抗体。方法:采用重组表达的人PD-L1 蛋白免疫BALB/ c 小鼠,通过杂交瘤细胞融合技术获得稳定分泌抗人PD-L1 单抗的阳性细胞株,ELISA 方法鉴定抗体的特异性、亲和力、亚型等方面特性;免疫印迹、间接免疫荧光方法对肿瘤细胞进行检测;肿瘤杀伤实验验证抗体阻断活性。结果:共获得2 株抗人PD-L1 单抗,抗体效价分别为1 2.56 106 和1 3 105 ,亲和力分别为1.5 109 L/ mol 和2.5 108 L/ mol,均与PD-L2 蛋白无交叉反应。免疫印迹、间接免疫荧光证实抗体有诊断作用。杀伤实验显示抗体有阻断作用。结论:共获得两株稳定分泌高效价、高特异性的抗人PD-L1 单抗的杂交瘤细胞株,能作为诊断抗体应用于肿瘤表型检测和预后有效性的评估。抗体的阻断功能可应用于联合CIK 细胞免疫治疗。