CTLA4 polymorphisms in Spanish patients with rheumatoid arthritis

Cytotoxic T-lymphocyte antigen 4 (CTLA4) polymorphisms located in the promotor region at positions -318 (C/T) and in exon 1 (49 A/ G) were investigated in 138 Spanish patients (37 men and 101 women) with rheumatoid arthritis and in 305 ethnically-matched healthy controls. When the allelic and genotypic frequencies corresponding to the CTLA4 -318 position were compared, no significant differences between patients and controls were found. However, when the CTLA4 49 A/G polymorphism was analysed, a significant increase of A/G heterozygous individuals among female patients (48.5% vs. 33.8% in controls; P=0.008; OR=2.0) was observed. This increase was absent among males (37.8%, P=NS). Analysis of the CTLA4 49 polymorphism with respect to HLA-DRB1 typing demonstrated a significant increase of A/G heterozygosity in the HLA-DR3-positive patient group compared with HLA-DR3-negative patient group (14/19, 74% vs. 49/119, 41%; P=0.009, OR=4.0). The increase of A/G genotype among HLA-DR3-positive patients was found in both males (4/6, 67%) and females' (10/13, 77%), although statistical differences were only reached in the female group. These results provide new insight into this complex association, confirm previous data from other studies, and suggest that the CTLA4 gene could be involved in the pathogenesis of rheumatoid arthritis.     

CTLA4 codon 17 dimorphism in patients with rheumatoid arthritis

Abstract: The genetic susceptibility to rheumatoid arthritis is conferred by genes in the human leukocyte antigen (HLA) region on chromosome 6, but additional genes may be involved to determine disease susceptibility. We have studied the distribution of the CTLA4 exon 1 polymorphism (49 A/G) in rheumatoid arthritis. This dimorphism at codon 17 results in an amino acid exchange (Thr/Ala) in the leader peptide of the expressed protein and was analyzed by PCR, SSCP and RFLP in 258 Caucasian rheumatoid arthritis patients and 456 controls. Rheumatoid arthritis patients were characterized by a decreased frequency of homozygotes for the Thr-17 substitution (32% versus 39%) and an overrepresentation of patients heterozygous for the Thr/Ala substitution (54% versus 46%). Gene frequencies for the Ala/Thr substitution differed only marginally from controls. In contrast, analyses of the CTLA4 exon 1 polymorphism with respect to HLA-DRB1*04 revealed significantly more patients with Ala in the homozygous (19% versus 15% controls) or heterozygous state (54% versus 39% controls) and less homozygous for Thr (27% versus 46% controls), with a particular increase of Ala/Ala genotypes among rheumatoid arthritis patients carrying the HLA-DRB1*0401 subtype. Among HLA-DRB1*04 negative rheumatoid arthritis patients, we observed no difference between the allele frequencies of the Ala-17 or Thr-17 substitution.     

腺病毒载体介导的共刺激分子融合蛋白对实验性自身免疫性心肌炎的作用

目的探讨腺病毒载体介导的共刺激分子融合蛋白CTLA4Ig与ICOSIg联合治疗对实验性自身免疫性心肌炎（EAM）的作用.方法猪心肌肌球蛋白免疫Lewis大鼠制成EAM模型.分别构建CTLA-4胞外域、ICOS胞外域与人IgG Fc段融合的腺病毒表达载体,常规方法生产表达上述融合蛋白的腺病毒用于治疗,免疫第14天注射后观察至第28天.第28天超声心动图检测心脏功能,苏木素-伊红（HE）染色观察心肌炎症程度,Western blot检测心肌CTLA-4、ICOS、ICOSL及B7-1、B7-2蛋白表达水平,ELISA检测血浆IL-2、IL-4和IFN-γ水平.结果CTLA4Ig、ICOSIg单独或联合治疗均使大鼠心功能指标、心肌炎症程度明显改善.Western blot显示联合治疗组CTLA-4、ICOSL及ICOS、B7-1蛋白表达下调,而B7-2表达差异无统计学意义.细胞因子平衡向TH2方向偏离.结论CTLA4Ig及ICOSIg联合阻断共刺激分子通路减轻EAM自身免疫性心肌损伤,改善大鼠心脏功能.其机制可能通过下调心肌组织CTLA-4、ICOS、ICOSL及B7-1蛋白表达.     

Upregulation of CD4+CD25+ T lymphocyte by adenovirus-mediated gene transfer of CTLA4Ig fusion protein in experimental autoimmune myocarditis

Objective: To explore the effects of adenovirus vector-mediated gene transfer of CTLA4Ig fusion protein on CD4⁺CD25⁺ T cells in experimental autoimmune myocarditis (EAM).

Methods: EAM was induced by porcine cardiac myosin as previously described. Adenovirus vector-mediated CTLA4Ig gene was administrated intravenously in EAM rats on days 1, 4 and 7, with EGFP as control. On day 21, myocardium histopathology was examined and CD4⁺CD25⁺ T cells were isolated. Proliferation and suppression assays were used to evaluate the suppressive capacity of CD4⁺CD25⁺ T cells in vitro. Relative mRNA level of Foxp3 and TGF-β was determined by quantitative real-time RT-PCR; expression of CTLA-4, B7-1 and B7-2 protein was compared with Western blot in CD4⁺CD25⁺ T_regs.

Results: Severe inflammatory lesions were observed in the hearts of EGFP-treated EAM rats and the untreated ones, while Ad–CMV–CTLA4Ig alleviated the myocarditis histologically. Adenovirus vector-mediated CTLA4Ig gene transfer up-regulated the proportion of CD4⁺CD25⁺ T_regs significantly. T cell proliferation was greatly inhibited in the CTLA4Ig group compared with the untreated and EGFP-treated groups in vitro. CTLA-4 and B7-2 proteins were down-regulated in the CTLA4Ig group, Foxp3 and TGF-β mRNA was up-regulated significantly by CTLA4Ig treatment.

Conclusions: Adenovirus vector-mediated CTLA4Ig gene transfer alleviated inflammation in EAM, one of the potential mechanisms is up-regulation of CD4⁺CD25⁺ T_regs.     

Upregulation of CD4+CD25+ T lymphocyte by adenovirus-mediated gene transfer of CTLA4Ig fusion protein in experimental autoimmune myocarditis

OBJECTIVE: To explore the effects of adenovirus vector-mediated gene transfer of CTLA4Ig fusion protein on CD4+CD25+ T cells in experimental autoimmune myocarditis (EAM). METHODS: EAM was induced by porcine cardiac myosin as previously described. Adenovirus vector-mediated CTLA4Ig gene was administrated intravenously in EAM rats on days 1, 4 and 7, with EGFP as control. On day 21, myocardium histopathology was examined and CD4+CD25+ T cells were isolated. Proliferation and suppression assays were used to evaluate the suppressive capacity of CD4+CD25+ T cells in vitro. Relative mRNA level of Foxp3 and TGF-beta was determined by quantitative real-time RT-PCR; expression of CTLA-4, B7-1 and B7-2 protein was compared with Western blot in CD4+CD25+ Tregs. RESULTS: Severe inflammatory lesions were observed in the hearts of EGFP-treated EAM rats and the untreated ones, while Ad-CMV-CTLA4Ig alleviated the myocarditis histologically. Adenovirus vector-mediated CTLA4Ig gene transfer up-regulated the proportion of CD4+CD25+ Tregs significantly. T cell proliferation was greatly inhibited in the CTLA4Ig group compared with the untreated and EGFP-treated groups in vitro. CTLA-4 and B7-2 proteins were down-regulated in the CTLA4Ig group, Foxp3 and TGF-beta mRNA was up-regulated significantly by CTLA4Ig treatment. CONCLUSIONS: Adenovirus vector-mediated CTLA4Ig gene transfer alleviated inflammation in EAM, one of the potential mechanisms is up-regulation of CD4+CD25+ Tregs.     

Mammary gland-specific secretion of biologically active immunosuppressive agent cytotoxic-T-lymphocyte antigen 4 human immunoglobulin fusion protein (CTLA4Ig) in milk by transgenesis

A major challenge in the field of transplantation is to prevent graft rejection and prolong graft survival. Tolerance induction is a promising way to achieve long-term graft survival without the need for potent immunosuppression and its associated side effects. The recent success of co-stimulatory blockade by the chimeric protein CTLA4Ig in the modulation of the recipient's immune system and the prolongation of graft survival in animal models suggests a possible application of CTLA4Ig in clinical transplantation. To produce sufficient amounts of CTLA4Ig for future clinical application, we sought to use the mammary gland as a bioreactor and produce CTLA4Ig in the milk of transgenic farm animals. Prior to the generation of transgenic farm animals, we tested our strategy in mice. Using the promoter of the sheep beta-lactoglobulin gene, we expressed our CTLA4Ig chimeric gene in the mammary gland of transgenic mice. The yield of CTLA4Ig was fivefold higher in transgenic milk than that from transfected cells. Purified milk-derived CTLA4Ig is biologically active and suppresses T cell activation. We showed that the production of CTLA4Ig in the milk has no adverse immunosuppression effect on the transgenic animals and the offsprings that were fed with the transgenic milk. The findings suggest that the approach to produce CTLA4Ig in milk by transgenesis is feasible; further studies involving farm animals are warranted.     

CTLA4Ig诱导细胞无能的作用机制探讨

IL 2受体α链 (又称CD2 5 )是T淋巴细胞活化的标志分子 ,CTLA4Ig所诱导的细胞无能CD2 5的表达下降。用FACS方法检测CTLA4Ig诱导的细胞无能的凋亡现象 ,结果发现未处理组与处理组间无差异 ;CTLA4Ig处理后的细胞无能Fas和FasL的表达 ,与未处理对照组无差异。用免疫印迹方法 ,检测发现CTLA4Ig诱导的细胞无能与未处理组相比P2 1Ras没有明显变化。用RT PCR方法检测一些细胞因子mRNA的表达水平 ,发现CTLA4Ig所诱导的细胞无能不能表达IL 2mRNA ,IFN γmR NA的表达下降 ,而IL 4mRNA、IL 10mRNA仍可表达 ,表明细胞无能的基因格局显示Th1基因受抑 ,有向Th2偏移倾向     

CTLA4—lg融合蛋白基因的表达及其生物学功能的初步研究

获得ＣＴＬＡ４全长基因并在真核表达系统中表达。方法通过ＲＴ－ＰＣＲ方法，从ＭＴ２细胞系克隆ＣＴ－ＬＡ４全长基因；经直物重叠和半巢式ＰＣＲ改造，获得含抑瘤素Ｍ信号肽的ＣＴＬＡ４胞外段ＤＮＡ，然后克隆至真核表达载体ｐＩｇ，转染ＣＯＳ和ＣＨＯ－Ｋ细胞表达。结论真核表达体系表达了有生物学活性的ＣＴＬＡ４－Ｉｇ。     

Altered collagen II peptides inhibited T-cell activation in rheumatoid arthritis

It has been reported that collagen II (CII)-derived peptide induced T-cell activation via its amino acids responsible for T-cell receptor (TCR) recognition. In this study, three altered CII263-272 peptide ligands (APL) containing multiple substitutions of TCR contact residues were synthesized. Their roles in inhibition of T-cell activation were evaluated in peripheral blood lymphocytes (PBL) of rheumatoid arthritis (RA) in vitro. It was shown that 41% (25/61) of RA patients were responsive to the wild-type antigenic CII263-272. In contrast, marginal or silent T-cell responses to the three APLs were found, accompanied by inhibitory effects on secretion of Th1 type cytokines and expression of cell surface markers, CD69 and CD25. In addition, T-cell activation induced by the wild-type antigenic CII263-272 was inhibited by all the three APLs in a dose-dependent manner. It is demonstrated that APLs with substitutions of TCR contact residues are capable of down-regulating T-cell responses in PBLs of RA, suggesting that the CII-derived APLs are potentially therapeutic in RA.     

CTLA4Ig和OX40Ig的表达及其生物学活性研究

目的构建p3．1／CTLA4Ig-IRES-OX40Ig真核表达载体，共同表达CTLA4Ig和OX40Ig，通过体外实验初步研究其生物学特性。方法通过特异引物扩增OX40胞外区的cDNA，经酶切、亚克隆、拼接构建了真核表达载体p3．1／CTLA4Ig．IRES-OX40Ig，并使之在体外进行表达，用RT-PCR、SDSPAGE和Western blot鉴定目的基因的表达，ELISA法测定目的基因的表达水平和混合淋巴细胞反应研究其抑制免疫应答的效应。结果测序证实所扩增的PCR产物是OX40胞外区的cDNA，其序列与GenBank中的相一致；成功构建了p3．1／CTLA4Ig-IRES-OX40Ig真核表达载体；RT-PCR、SDS-PAGE和Western blot结果显示，表达的蛋白为CTIA41g和OX40Ig，ELISA结果提示，该两种蛋白均得到了高效表达，混合淋巴细胞反应结果证实转染了p3．1／CTLA4Ig-IRES-OX40Ig的CHO细胞培养上清可以有效地抑制异基因淋巴细胞的刺激作用，其抑制效果强于转染p3．1／CHA4Ig和p3．1／OX40Ig的CHO细胞培养上清。结论成功构建了含CTLA4Ig和OX40Ig的真核表达载体，并在体外能够同时得到表达；体外实验证实该两种分子协同作用可以有效抑制免疫廊答，并且优于该两种分子单独作用时的抑制效果。     

CTLA4Ig: bridging the basic immunology with clinical application

After a very long and windy road, in December of 2005 the FDA approved CTLA4Ig for the treatment of rheumatoid arthritis. Orencia is the first-in-class antagonist of CD28 costimulation. In this perspective, we discuss the science that led to CTLA4Ig development and the clinical challenges in bringing the drug from the bench to the bedside.     

The distinct subgroup of patients with rheumatoid arthritis shown by Ig G3-reactive rheumatoid factor

The reactivity of rheumatoid factor (RF) with immunoglobulins of the IgG3 subclass was examined in 49 patients with rheumatoid arthritis (RA) using two types of IgG3 myeloma (routine and IgG3m-15 allotype). Among 49 patients, serum from eight cases showed positive reactivity with both types of IgG3 myeloma by radio-immunoassay (RIA). The isotype of IgG3-reactive RF was not specific; it belonged to the IgM class as well as the IgG subclasses IgG1, IgG2 and IgG4. The patients with IgG3-reactive RF belonged to the clinically-severe classification of RA, having a high erythrocyte sedimentation rate (ESR), high titre in the RA hemagglutination (RAHA) test, and above all they had low levels of complement. Generally, it is concluded that patients with IgG3-reactive RF have serious arthritis and that IgG3-reactive RF might play an important role in the inflammatory process. Furthermore, it was also shown that the RF-reactive site was not associated with the protein-A binding site of IgG3, since RF reacting with IgG3m-15 reacted similarly with routine IgG3, regardless of the difference of the protein-A binding activity. This was confirmed by adding protein-A to the reaction of RF and IgG3m-15 which binds with protein-A. This suggests that the actual reactive site of RF is different to the site that binds protein-A.     

Local gene therapy with CTLA4-immunoglobulin fusion protein in experimental allergic encephalomyelitis

It has been reported previously that the induction phase of experimental allergic encephalomyelitis (EAE) is highly sensitive to systemic blockade of stimulation via MHC class II molecules and co-stimulation via the CD28 : CD80/CD86 pathways. In contrast, the effector phases of EAE were relatively unaffected by similar treatments using MHC class II antigen (Ag)-specific mAb and cytotoxic T lymphocyte antigen (CTLA)4-Ig fusion proteins in some studies. This has been attributed to different sensitivities of effector cell function or the poor penetrance of inhibitory proteins into the central nervous system (CNS). To examine this question further, MHC class II Ag-specific mAb and CTLA4-Ig were delivered directly into the CNS following EAE induction, and both were found to inhibit disease. While it was found that systemic administration of mouse CTLA4-Ig could also inhibit the progression of effector immune responses when administered shortly before or during clinical disease, these were significantly more active when delivered directly into the CNS, which probably involved an action on both CD28 ligands, CD80 and CD86. Although mouse CTLA4-human Ig was therapeutically less efficient than mouse CTLA4-mouse Ig protein, probably due to the enhanced immunogenicity and lower functional activity, gene delivery of CTLA4-human Ig into the CNS using a non-replicating adenoviral vector was more effective than a single injection of CTLA4-human Ig protein. Gene delivery significantly ameliorated the development of EAE, without necessarily inhibiting unrelated peripheral immune responsiveness. Local gene delivery of CTLA4-Ig may thus be an important target for immunotherapy of human autoimmune conditions such as multiple sclerosis.     

Negative regulation of TCR signaling and T-cell activation by selective protein degradation

Protein degradation was previously considered to be a nonspecific cellular process that eradicated abnormal or damaged proteins. Current evidence indicates, however, that T cells use this mechanism to selectively eliminate activated T-cell receptors (TCRs) and signaling molecules, and consequently control the duration and specificity of TCR signaling.     

Association of the CTLA4 3' untranslated region polymorphism with the susceptibility to rheumatoid arthritis

Cytotoxic T-lymphocyte antigen 4 (CTLA4) gene polymorphism located in the 3' untranslated region (UTR) was investigated in 141 Spanish patients (38 men and 103 women) with rheumatoid arthritis (RA) and in 194 ethnically-matched healthy controls. Twenty alleles having different numbers of (AT) repeats (from 7 to 32) were found in this population. (AT)7 and (AT)16 were the most frequent alleles, and accounted for almost two-thirds of the allelic frequency in the control population. Consequently, alleles were assigned as L (large: 16 or more AT repeats) or S (short: less than 16 AT repeats). When the L/S distribution in patients and controls were compared, an increase of L alleles was observed among patients (49.9% vs. 39.7%; p = 0.02; p(c) = 0.04, odds ratio [OR] = 1.46; 95% confidence interval [CI], 1.06-2.01). Hence, the frequency of S alleles was decreased among patients (51.1% vs. 60.3%; p = 0.02; p(c) = 0.04; OR = 0.69; 95%CI, 0.50-0.95). Moreover, a statistically significant decrease in the frequency of S/S individuals was observed among RA patients (27.7% versus 40.7%; p = 0.01; p(c) = 0.03; OR = 0.56; 95%CI, 0.34-0.91). These differences were irrespective of the HLA "shared epitope" (SE) status, and were observed similarly among SE+ as well as among SE- patients. After combining these data with other reported previously by us, from studies of CTLA4 49 (A/G) and -318 (C/T) polymorphisms, we conclude that the strongest association between CTLA4 gene polymorphisms and RA susceptibility occurs with the 3' UTR polymorphism.     

CTLA4Ig对丝裂原诱导的淋巴细胞反应的影响

本研究证明CTLA4Ig 与B7 分子结合后, 可以阻断B7 与CD28 的结合。CTLA4Ig 可以抑制丝裂原所触发淋巴细胞的增殖反应, 同时抑制细胞因子IL 2 ,IL 4 的产生以及IL 2R 的表达。表明CTLA4Ig 可以通过不同的途径影响T淋巴细胞的活化     

人CTLA4Ig腺病毒载体的构建及其生物学功能研究

目的：通过同源重组构建CTLA4Ig腺病毒载体。研究其生物学活性，并用于基因治疗诱导心脏移植耐受。方法：通过基因重组技术，将CTLA4Ig基因克隆至腺病毒穿梭质粒pCA13中，然后将该质粒与腺病毒辅助质粒同源重组，经过293细胞包装，构建CTLA4Ig腺病毒载体，用RT-PCR，SDS-PAGE及Western blot等技术，检测包装的病毒感染293细胞后CTLA4Ig蛋白的表达及分泌，通过体外实验，观察病毒感染的293细胞上清对混合淋巴细胞反应（MLR）的抑制作用，通过大鼠体内实验，检测用CTLA4Ig腺病毒载体基因治疗后，CTLA4Ig在体内的表达及分泌，通过体外实验，观察病毒感染的293细胞上清对混合淋巴细胞反应（MLR）的抑制作用，通过大鼠体内实验，检测用CTLA4Ig腺病毒载体基因治疗后，CTLA4Ig在体内的表达。结果：CTLA4Ig腺病毒载体构建成功，体外实验证实，CTLA4Ig腺病毒感染的293细胞上清液，能够抑制异基因脾细胞的单向MLR，体内实验表明，经过静脉途径给予受体大鼠CTLA4Ig腺病毒载体，能够诱导移植耐受，延长心脏移植物的存活。结论：构建的CTLA4Ig腺病毒载体，体外感染293细胞能够分泌CTLA4Ig蛋白，该蛋白可抑制T细胞的活化，CTLA4Ig腺病毒载体可用于体内基因治疗诱导移植耐受。     

Interleukin-21 induces T-cell activation and proinflammatory cytokine secretion in rheumatoid arthritis

Interleukin (IL)-21 is a CD4+ T-cell-derived cytokine, which is involved in innate and adaptive immune response. In this study, we analysed IL-21 receptor (IL-21R) expression in peripheral blood and synovial fluid mononuclear cells, and investigated the role of IL-21 in the induction of proinflammatory cytokine production by peripheral blood T cells (PB-T) and synovial fluid T cells (SF-T) from patients with rheumatoid arthritis (RA). Immunohistochemical staining demonstrated that IL-21R-positive cells were significantly increased in inflamed synovial tissues of RA patients compared with osteoarthritis (OA) and healthy controls. Flow cytometric analysis confirmed that IL-21R was mainly expressed in freshly isolated CD4, CD8, B and NK cells from peripheral blood and synovial fluid, but decreased gradually in T cells 24 h after anti-CD3 stimulation. PB- and SF-T cells from RA patients were more responsive to IL-21 when compared with controls. Importantly, isolated PB- or SF-T cells from RA patients, when stimulated with IL-21 and anti-CD3 MoAb, secreted markedly higher levels of TNF-alpha and IFN-gamma than controls. These data indicate that IL-21R is overexpressed in the inflamed synovial membrane and in peripheral blood or synovial fluid leukocytes of RA patients, and that IL-21 enhances local T-cell activation, proliferation and proinflammatory cytokine secretion. Thus, blockade of IL-21R signalling pathway may have a therapeutic potential in acute RA patients.     

Co-stimulatory modulation in rheumatoid arthritis: the role of (CTLA4-Ig) abatacept

Associations between rheumatoid arthritis (RA) susceptibility and polymorphism in multiple immunoregulatory genes suggest a role of altered T cell function in the disease. The growing relevance of the oxidative stress in RA synovitis, which results in a number of T cell signalling abnormalities, is reinforced by the demonstration of a direct NO inducing activity through the shared epitope of the HLA class II molecules HLA-DRbeta1, with secondary lymphocytes oxidative damage. Direct T cell/macrophage contact-dependent activation, one of the driving mechanisms of synovitis, is mediated by co-stimulatory molecules as well as cell membrane cytokines and may also result in an impaired suppressive function of T regulatory cells (Treg) in RA joints. The fusion of CTLA4 extracellular binding domain to the Fcgamma1 allows to obtain a soluble CTLA4 receptor, the dimeric recombinant human fusion protein abatacept (CTLA4-Ig). The improved knowledge of the CTLA4-B7 co-stimulation regulatory mechanisms by signals delivered into DCs and Tregs provides multiple potential targets for the abatacept treatment. CTLA4-Ig shows the capacity, either ex vivo or in vivo, to interrupt at multiple steps the ongoing inflammatory and destructive process, and to concur in restoring the immunoregulatory balance in RA.