重组人可溶性B淋巴细胞刺激因子及其突变体的克隆、表达及活性测定

采用RT PCR方法从人外周血白细胞总RNA中钓取人可溶性B淋巴细胞刺激因子 (humansolubleBlym phocytestimulator,hsBLyS)的cDNA片段 ,再运用基因重组手段 ,利用通用型质粒pBV2 2 0构建表达载体pBV2 2 0 /hsBLyS。经测序鉴定后 ,以之为模板使用重叠PCR法扩增得到hsBLyS的两个点突变体hsBY A(Cys14 6→Ala14 6)和hsBY V (Cys14 6→Val14 6)的基因片段 ,构建表达载体 pBV2 2 0 /hsBY A及 pBV2 2 0 /hsBY V。经测序无误后 ,将上述 3种载体分别转化大肠杆菌DH5α并诱导重组蛋白质表达 ,薄层扫描结果显示 3种蛋白质在DH5α中表达量都在 2 0 %～ 30 %之间。再分别运用变性、凝胶过滤层析及复性等手段纯化目的蛋白质 ,最后通过B淋巴细胞增殖实验检测纯化产物促人B细胞增殖的活性。实验结果表明 ,3种重组蛋白质都能明显刺激人B细胞增殖 ;统计学检验显示 ,突变体rhsBY V较野生型rhsBLyS的促人B淋巴细胞增殖活性显著增强。     

B淋巴细胞刺激因子（BLyS）研究进展

B淋巴细胞刺激因子（BLyS）是1999年新发现的一种重要的细胞因子,属于肿瘤坏死因子(TNF)超家族成员.在体液免疫调控中起重要作用.它能强烈地刺激B淋巴细胞的增殖和分化并分泌大量免疫球蛋白(主要为IgM);在体外其过量表达能促进多种B系肿瘤细胞的生长.BLyS转基因小鼠出现严重的红斑狼疮样症状.对BLyS的基因和蛋白质结构、免疫调控功能、受体和信号通路及其在自身免疫性疾病和恶性肿瘤中的作用进行了综述.     

小鼠核因子κB受体活化因子配基(RANKL)活性区cDNA在毕赤酵母中分泌型表达

由小鼠骨组织提取总RNA ,采用RT PCR扩增得到小鼠核因子κB受体活化因子配基(RANKL)活性区域cDNA .将该cDNA片段克隆入表达载体pPIC9,重组载体转化巴斯德毕赤酵母GS115细胞 ,筛选Mut+表型 ,经甲醇诱导实现目的基因的分泌型表达 .Tricine SDS PAGE显示 ,表达产物约 2 6kD ,经Western印迹鉴定 ,表达产物可被RANKL抗体识别 .采用硫酸铵盐析、CM SephadexC 2 5层析纯化重组蛋白 .经测定 ,发酵液上清重组蛋白表达量约 11mg L .采用破骨细胞样细胞(osteoclastlikecell,OLC)诱导分化实验检测重组蛋白的生物活性 ,证实该重组蛋白可以促进OLC的生成 ,并呈现剂量依赖关系     

SARS-CoV-2重组S1和S蛋白疫苗诱导保护性免疫的研究*

目的:评价新型冠状病毒(SARS-CoV-2)重组S1蛋白和S蛋白疫苗对SARS-CoV-2的免疫保护效果。方法:将SARS-CoV-2重组S1蛋白和S蛋白分别联合氢氧化铝佐剂以0.1 μg/只、1 μg/只、5 μg/只、10 μg/只不同剂量接种6~8周BALB/c纯系健康雌性小鼠。第二次免疫后采血通过酶联免疫吸附试验(ELISA)检测血清中IgG抗体效价,通过假病毒中和试验比较免疫小鼠血清对SARS-CoV-2野生型株(WT)、英国株(B.1.1.7)、巴西株(P.1)、印度株(B.1.617.2)、Mu毒株(B.1.621)和南非株(501Y.V2-1)六种假病毒毒株中和活性效价,取脾细胞通过酶联免疫斑点技术(ELISpot)检测免疫小鼠的细胞免疫水平。结果:SARS-CoV-2重组S和S1蛋白都能诱导小鼠产生较强的IgG抗体水平。免疫S1蛋白的小鼠血清对SARS-CoV-2野生型株、英国株、巴西株有明显的中和活性,免疫S蛋白的小鼠血清除了对SARS-CoV-2野生型株、英国株、巴西株有明显中和活性之外,对印度株也有明显的中和活性,两种蛋白质免疫的小鼠血清均对野生型株中和效果最强。S蛋白免疫的小鼠脾细胞能够显著诱导出γ干扰素(IFN-γ)和白介素-4(IL-4)的产生。S蛋白诱导产生的IgG抗体、中和抗体、细胞免疫水平均高于S1。结论:SARS-CoV-2重组S蛋白疫苗能够诱导产生较强的保护性免疫应答。     

糖尿病诱导serpinE1分泌增多对心肌细胞NF-κB核易位及凋亡的影响

摘要 目的：探讨糖尿病诱导serpinE1分泌增多是否引起心肌细胞NF-κB核易位及凋亡。方法：8周龄C57BL/6J小鼠随机分为对照组和糖尿病组,糖尿病模型应用链脲佐菌素腹腔注射诱导。体外试验中,应用低糖（5.5 mmol/L）及高糖（25 mmol/L）浓度培养基分别处理大鼠心肌H9C2细胞。ELISA法分别检测小鼠血清及细胞培养上清中的serpinE1水平,Western Blot分别检测心脏组织及细胞中 caspase-3、cleaved caspase-3以及细胞浆、细胞核中NF-κB蛋白表达。此外,H9C2细胞分为三组：对照组、serpinE1重组蛋白处理组、JSH-23与serpinE1重组蛋白共同处理组,Western Blot检测上述相同指标。结果：糖尿病小鼠血清及高糖处理的细胞培养上清中serpinE1水平较对照组显著增加(P<0.05)。同对照组相比,细胞核/细胞浆NF-κB、cleaved caspase-3/ caspase-3在糖尿病小鼠心肌组织及H9C2细胞高糖处理组中显著上升(P<0.05)。此外,serpinE1重组蛋白处理后细胞核/细胞浆NF-κB以及cleaved caspase-3/ caspase-3同对照组相比,均显著增加(P<0.05),而JSH-23则减弱了serpinE1的这些效应。结论：糖尿病诱导serpinE1分泌增多促进心肌细胞NF-κB核易位及凋亡。     

人B淋巴细胞刺激因子C端肽的免疫增强作用

用套式PCR从人胎脑cDNA文库中克隆了B淋巴细胞刺激因子C端肽 (C terminalpeptideofBlymphocytestimulator,C BLyS)的cDNA。在大肠杆菌BL2 1CodonPlus (DE3)RIL中以包含体形式表达了C BLyS。对包含体的复性条件进行了摸索 ,建立了C BLyS的透析复性与纯化方法。经复性和纯化的C BLyS可结合其受体B细胞成熟抗原 (Bcellmaturationantigen ,BCMA) 人IgG1Fc融合蛋白 ,刺激体外培养的小鼠脾脏细胞增殖 ,并且可明显增强小鼠对溶菌酶的免疫应答水平。     

氨基酸序列突变对TFPI生物半衰期和生物活性的影响

通过对个别氨基酸突变的研究,获得了保持良好生物活性的长半衰期组织因子途径抑制因子(tissue factor pathwayinhibitor,TFPI)重组蛋白的有效途径.采用定点诱变和基因重组技术,首先在TFPI cDNA特定位点形成一个位点的沉默突变,以提高TFPI在毕赤酵母细胞内的表达量,此cDNA称为mTFPI.在此基础上,通过系列位点突变,形成3个羧基端突变体:m0TFPI、m1TFPI和m2TFPI.将上述4种TFPI cDNA与表达质粒pPic9连接,转染大肠杆菌,通过PCR和DNA测序确认重组质粒,转染酵母细胞GS115,甲醇诱导表达重组蛋白.采用层析方法纯化TFPI重组蛋白,用125I标记重组蛋白,静脉注射给药,比较四者在SD大鼠体内血浆代谢清除速度.用底物显色法测定重组蛋白抑制凝血因子Xa(Fxa)的活性,比较各株TFPI重组蛋白突变体在体内、体外对FXa的抑制作用及肝素对各株TFPI重组蛋白功能的影响.结果显示,相比野生型TFPI重组蛋(mTFPI)而言,3株羧基端突变体m0TFPI、m1TFPI、m2TFPI在SD大鼠体内血浆代谢清除时间均有不同程度延长,其生物代谢半衰期分别是mTFPI的1.5倍、1.9倍和大于2倍,与m-TFPI相比,3个rTFPI突变体在体内、体外抑制FXa的作用无明显减弱,与肝素的结合能力及协同能力也无明显减弱.结果表明,m0TFPI、m1TFPI和m2TFPI在生物半衰期得到明显延长的同时,仍保持良好的抑制Fxa的生物活性.     

连翘酯苷对小鼠脾脏淋巴细胞体外增殖与分泌功能的影响

目的分析连翘酯苷（FS）对小鼠脾脏T和B淋巴细胞增殖、分泌NO和TNF-α的影响,初步探讨其免疫调节作用机制。方法无菌操作分离小鼠脾脏,制备脾脏细胞并用含10%胎牛血清的RPMI 1640培养,在培养液中分别加入刺激剂刀豆蛋白（ConA）和脂多糖（LPS）以及不同浓度40、80、160μg/mL的FS共培养不同时间,采用MTT法检测T和B淋巴细胞的吸光度变化,ELISA和Griess法分别检测细胞分泌TNF-α和NO的水平。结果低浓度和中浓度FS对ConA诱导T淋巴细胞24 h和48 h后细胞增殖和存活率明显提高,诱导时间延长至72 h后FS明显抑制细胞转化;低浓度FS对LPS诱导脾脏B淋巴细胞24 h后细胞增殖和生存率显著提高;FS促进小鼠脾脏T和B淋巴细胞分泌NO;FS促进B淋巴细胞分泌TNF-α,中浓度FS促进T淋巴细胞分泌TNF-α而高浓度反而抑制其分泌。此外,FS对环磷酰胺（CY）处理小鼠的脾脏淋巴细胞体外增殖有明显影响,对细胞NO分泌影响不显著。结论结果提示FS可能通过影响小淋巴细胞增殖和细胞因子分泌而调节免疫细胞功能。     

携带小鼠白介素-4截短型突变体基因的5型腺相关病毒载体的构建及外源蛋白的体外表达

目的:制备携带碳端结构域缺失的小鼠白介素-4(Interleukin-4,IL-4)基因突变体的5型重组腺相关病毒(recombinant adeno-associated virus, r AAV)并在细胞水平检测其介导的外源蛋白表达情况。方法:通过分子克隆技术构建携带小鼠IL-4碳端22个氨基酸缺失的突变体的表达质粒pSNAV-mIL-4ΔC22,三质粒共转染法制备重组的5型AAV病毒,体外感染人支气管上皮样细胞系16HBE和BEAS-2B,并通过Western blot和ELISA检测外源蛋白表达。结果:DNA测序表明构建的小鼠IL-4碳端第118位氨基酸位点处截短的突变体基因表达序列正确无误,制备的重组病毒载体r AAV5-mIL-4ΔC22滴度约为3×10~(11)vg/m L。r AAV5-GFP感染16HBE和BEAS-2B细胞后36小时开始可见持续稳定的荧光蛋白表达,重组病毒r AAV5-mIL-4ΔC22感染16HBE和BEAS-2B细胞后外源蛋白在培养上清中呈分泌型表达。结论:本研究成功构建了携带小鼠IL-4碳端结构域缺失型突变体的AAV表达质粒并制备了重组病毒r AAV5-mIL-4ΔC22,该病毒可有效转染16HBE和BEAS-2B细胞并介导外源基因分泌表达截短型小鼠IL-4突变体蛋白。     

小鼠核因子κB受体活化因子配基活性区的克隆、表达及生物活性分析

核因子κB受体活化因子配基是诱导破骨细胞分化、成熟的关键因子,在生物医学研究中应用广泛。本实验以小鼠的骨髓细胞cDNA为模板,采用PCR技术获得小鼠核因子κB受体活化因子配基活性区基因,并将该基因克隆至His标签的融合蛋白表达载体pET28a(+),经鉴定正确的质粒转化至BL21表达菌株中。通过调节诱导目的蛋白表达的培养温度、IPTG浓度及诱导时间,筛选出重组融合蛋白表达的最佳条件。将纯化后的重组蛋白稀释成不同浓度,刺激小鼠破骨前体细胞Raw264.7细胞分化,经抗酒石酸酸性磷酸酶染色后可见破骨细胞的形成,表明该重组蛋白具有较好的生物活性,可替代商品化的鼠源核因子κB受体活化因子配基。     

Construction and function of two Cys146-mutants with high activity, derived from recombinant human soluble B lymphocyte stimulator

B lymphocyte stimulator (BLyS) is a novel member of tumor necrosis factor (TNF) ligand family that is important in B cell maturation and survival. Previous studies were almost related to the function or mechanism of its wild type. Here, we constructed two site-directed mutants of the recombinant human soluble BLyS, the BY-A and BY-V, and found that BY-V ranked the highest whenever in the process of promoting proliferation of B lymphocytes in vitro or stimulating total serum IgG and IgM secretion in vivo. Besides, assays for the biological responses of human leukemic cell lines to BLyS, BY-A and BY-V demonstrated that they could suppress the proliferation of Raji cells but promote the growth of THP-1. The discovery of BY-V with high activity will help come to a conclusion that the mutation of Cys146 to Val146 might improve the biological activity of BLyS.     

Two observed regions in B lymphocyte stimulator important for its biological activity

B lymphocyte stimulator (BLyS),a member of the tumor necrosis factor superfamily ofligands,is a crucial survival factor for B cells.We successfully constructed seven mutants of the functionalsoluble fragment of human BLyS (named cBLyS,amino acid 134-285),including three deletion mutants andfour site-directed mutants.All the mutant proteins were expressed in Escherichia coli and purified by Ni-NTA affinity chromatography.The biological activities of these mutants were assessed by the ligand-recep-tor binding assay,B cell proliferation assay and immune effect response in vivo.Our results indicated thatfour residues,H~(218),F~(220),T~(228) and L~(229),are indispensable for the biological activity of cBLyS,whereas tworegions,amino acid 134-148 and amino acid 271-285,are related to the biological activity of BLyS.Theprotein of deletion of amino acid 134-148 leads to a complete defection in raising the antigen-specific IgMtiter.The deletion of amino acid 271-285 reduces the effectiveness compared with the native cBLyS.Thisindicates that the region of amino acid 134-148 is indispensable for cBLyS to function normally.     

Cutting edge: a role for B lymphocyte stimulator in systemic lupus erythematosus

Increased levels of B lymphocyte stimulator (BLyS) are associated with systemic autoimmunity in animal models of spontaneous autoimmune disease, and transgenic animals expressing BLyS develop typical autoimmune disease. Here, we demonstrate significant elevations of BLyS in the patients with systemic lupus erythematosus (SLE). The BLyS isolated from the sera of SLE patients had the same m.w. as the natural soluble form and was able to stimulate B cell activation in vitro. Increased BLyS in SLE patients was partially associated with higher levels of anti-dsDNA Ab of the IgG, IgM, and IgA classes, but not associated with the disease activity. Our results suggest that BLyS may be a useful marker for early activation of an autoimmune diathesis and likely plays a critical role in triggering activation of self-Ag-driven autoimmune B cells in human SLE. BLyS may provide an effective therapeutic target in systemic autoimmunity.     

计算机辅助设计可溶性BLyS受体, eBCMA-Fc 融合蛋白及其在大肠杆菌中的表达&#61472;

B 细胞成熟抗原 (BCMA)是 B淋巴细胞刺激因子(BLyS)的受体之一．它的胞外区与人IgG1 Fc的融合蛋白eBCMA-Fc,又称为诱饵受体,具有拮抗BLyS的活性．为了设计新的拮抗肽,基于BCMA和Fc的晶体结构,通过计算机图形学技术、分子模拟方法,建立了eBCMA-Fc融合蛋白的三维理论结构．利用均方根位移（root mean square distance, RMSD）对eBCMA-Fc融合蛋白与单体eBCMA、Fc构象差异进行分析．融合蛋白eBCMA-Fc中的eBCMA段与单体eBCMA的主链碳原子间RMSD值为0.036 nm,Fc段与单体Fc的主链碳原子间RMSD值为0.064 nm．结果表明,对比单体,融合蛋白eBCMA-Fc并未因eBCMA与Fc直接连接而发生构象的变化．分子对接方法显示,融合蛋白eBCMA-Fc中的BCMA与BLyS作用,而Fc扮演着稳定BCMA构象的支架作用．为进一步验证上述理论分析,构建eBCMA-Fc融合基因,并将载有eBCMA-Fc融合基因的原核表达质粒转化BL21 (DE3)菌、在细菌中表达．目的蛋白经蛋白A亲和柱纯化大约为36 kD,与理论预测值34 kD相近．免疫印迹表明抗人IgG抗体能够识别eBCMA-Fc融合蛋白．ELISA证实,eBCMA-Fc融合蛋白能够结合BLyS．随着eBCMA-Fc融合蛋白增加,结合BLyS的融合蛋白也相应增加．而对照人IgG,即使在高浓度条件下,也不结合BLyS．此外,eBCMA-Fc 融合蛋白能够抑制BLyS对B细胞肿瘤Daudi细胞的作用．这些研究为下一步设计和筛选BLyS拮抗肽提供了实验基础．     

Immune opsonins modulate BLyS/BAFF release in a receptor-specific fashion

TNF ligand superfamily member 13B (B lymphocyte stimulator (BLyS), B cell activating factor (BAFF)) promotes primary B cell proliferation and Ig production. While the soluble form of BLyS/BAFF is thought to be the primary biologically active form, little is known about the regulation of its cleavage and processing. We provide evidence that Fcgamma receptor cross-linking triggers a rapid release of soluble, biologically active BLyS/BAFF from myeloid cells. Surprisingly, this function is primarily mediated by FcgammaRI, but not FcgammaRIIa as defined by specific mAb, and can be initiated by both IgG and C reactive protein as ligands. The generation of a B cell proliferation and survival factor by both innate and adaptive immune opsonins through engagement of an Fcgamma receptor, which can also enhance Ag uptake and presentation, provides a unique opportunity to facilitate Ab production. These results provide a mechanism by which Fcgamma receptors can elevate circulating BLyS levels and promote autoantibody production in immune complex-mediated autoimmune diseases.     

BLyS and APRIL form biologically active heterotrimers that are expressed in patients with systemic immune-based rheumatic diseases

BLyS and APRIL are two members of the TNF superfamily that are secreted by activated myeloid cells and have costimulatory activity on B cells. BLyS and APRIL share two receptors, TACI and BCMA, whereas a third receptor, BAFF-R, specifically binds BLyS. Both BLyS and APRIL have been described as homotrimeric molecules, a feature common to members of the TNF superfamily. In this study, we show that APRIL and BLyS can form active heterotrimeric molecules when coexpressed and that circulating heterotrimers are present in serum samples from patients with systemic immune-based rheumatic diseases. These findings raise the possibility that active BLyS/APRIL heterotrimers may play a role in rheumatic and other autoimmune diseases and that other members of the TNF ligand superfamily may also form active soluble heterotrimers.     

Expression and purification of a soluble B lymphocyte stimulator mutant modified with the T-helper cell epitope

The DNA encoding soluble B lymphocyte stimulator (134–285 amino acids, sBLyS) mutant with residues 217–224 replaced by two glycines (named msBLyS) was constructed. The sequence encoding a foreign immunodominant T-helper epitope from ovalbumin (OVA) was then coupled to the 5′-end of msBLyS cDNA. After being sequenced, the recombinant DNA was ligated into the prokaryotic expression vector pQE-80L. The recombinant protein was produced in E. coli DH5α after induction with IPTG with the yield of more than 40% of total bacterial protein. The recombinant protein was purified with Ni-NTA chromatography and Sepharcryl S200 chromatography to a purity of more than 98%. The BALB/c mice, immunized with the recombinant protein, produced anti-BLyS antibodies at a high level, which indicated that the recombinant BLyS mutant modified with T-helper epitope elicited polyclonal antibodies with cross-reactivity with BLyS in vivo. This recombinant protein may therefore be used as immune inhibitor of BLyS for treating BLyS -associated autoimmune diseases.     

The rearranged V(H) domain of a physiologically selected anti-single-stranded DNA antibody as a precursor for formation of IgM and IgG antibodies to diverse antigens

It has been proposed that autoreactivity of modest affinity contributes to positive selection of a preimmunization B cell repertoire, whereas high-affinity autoreactivity leads to negative selection. This hypothesis predicts that a B cell producing a physiologically selected unmutated ssDNA-binding Ab should be a precursor of cells that respond to diverse exogenous Ags. To test this prediction, we prepared transgenic mice bearing the rearranged V(H) domain of an IgM Ab from a nonautoimmune mouse immunized with a DNA-protein complex, poly(dC)-methylated BSA. The Ab, dC1, binds both poly(dC) and ssDNA. It is encoded by V(H) and V(L) gene segments with no mutations, suggesting that the producing cell may have been selected before and activated during immunization. The dC1V(H) transgene was targeted to the IgH locus. In heterozygous mice, on a nonautoimmune C57BL/6 background, the transgene allotype was expressed on B cell surfaces and in serum Ig, but about one-third of B cells expressed the endogenous allele instead. Total serum Ig concentrations were normal and included both transgene- and endogenous gene-coded IgM and IgG. The transgene V(H) D(H)J(H) was expressed in splenic IgM cDNA with few or no mutations, and in IgG cDNA with multiple mutations. The transgene allotype was also expressed in Abs formed on immunization with thyroglobulin, pneumococcal polysaccharide, and ssDNA-methylated BSA. Consistent with the hypothesis, cells with a rearranged autoreactive V(H) domain selected for reactivity with a form of ssDNA did serve as precursors for cells producing IgM and IgG Abs to diverse Ags.     

BLyS受体TACI、BCMA与人IgG1 Fc融合蛋白在哺乳动物细胞中的表达与鉴定

从人肝脏和肾脏cDNA文库中扩增了人IgG1Fc与B淋巴细胞刺激因子 (BLyS)的受体TACI及BCMA的胞外编码区 ,构建了TACI Fc及BCMA Fc融合表达质粒pSec1 Fc TACI与 pSec1 Fc BCMA ,并使用电穿孔法转染COS 7细胞 ,从 1L无血清培养上清中可纯化得到分泌表达的TACI Fc与BCMA Fc融合蛋白约 2mg。为获得TACI Fc与BCMA Fc的稳定来源 ,构建了TACI Fc与BCMA Fc的CHO稳定表达细胞株。免疫沉淀和ELISA结果显示 ,TACI Fc及BCMA Fc能特异性地结合其配体BLyS而不与BLyS同家族的TNF结合。TACI Fc及BCMA Fc可阻断BLyS对体外培养的小鼠B淋巴细胞的促增殖作用     

sBAFF mutants induce neutralizing antibodies against BAFF

B cell activating factor belonging to the TNF family (BAFF) is a novel member of the tumor necrosis factor (TNF) ligand family and plays an important role in B lymphocyte maturation and survival. Overexpression of BAFF is closely involved in the pathogenesis and progression of many kinds of autoimmune disorders; therefore, BAFF has been considered as an ideal therapeutic target for these conditions. In this study, we generated several candidate immune inhibitors of human BAFF by conjugating foreign immunodominant T-helper cell (Th) epitopes to the N- or C-terminus of five BAFF mutants. The recombined proteins were successfully expressed in Escherichia coli (E. coli) and purified by Ni-NTA chromatography. BALB/c mice immunized with the recombinant proteins produced high levels of anti-BAFF antibodies, and their sera inhibited the lymphocyte proliferation-inducing activity of recombinant soluble BAFF and natural soluble BAFF. Moreover, antibodies cross-reactive with BAFF were detected in sera from hu-SCID mice immunized with the recombinant proteins. These results indicated that the recombinant BAFF mutants modified with Th epitopes could induce neutralizing antibodies against BAFF in vivo. This study may provide a valuable strategy for treating BAFF-associated autoimmune diseases.