Influence of costimulatory molecules on immune response to Leishmania major by human cells in vitro

The importance of CD40, CD80, and CD86 costimulatory molecules in anti-Leishmania immune responses has been established in murine models. A role for these costimulatory molecules in human anti-Leishmania immune responses was investigated in this study. Autologous macrophages and peripheral blood leukocytes (PBL) were prepared from peripheral blood mononuclear cells of Leishmania-naive donors and cultured with or without Leishmania major in various combinations. After 7 days of culture, high levels of CD40 and CD86 were expressed on macrophages in the presence or absence of L. major. When macrophages were cultured for an additional 7 days with PBL, expression of all three costimulatory molecules was detected. When L. major was present in these cultures, the expression of CD80, and to a lesser extent CD40, on macrophages was enhanced. Blockade of CD80, CD86, or both molecules (in the order of greatest effect) in cultures containing macrophages, PBL, and L. major significantly inhibited the production of gamma interferon, interleukin-5 (IL-5), and IL-12. Blockade of CD40-CD154 interactions also significantly inhibited production of these cytokines in response to L. major. Production of IL-10 was unaltered by the blockade of these costimulatory molecules. Thus, these data suggest that CD40, CD80, and CD86 expression and regulation may significantly impact anti-Leishmania immune responses in humans.     

Trypanosoma cruzi infection induces differential modulation of costimulatory molecules and cytokines by monocytes and T cells from patients with indeterminate and cardiac Chagas' disease

Interactions between macrophages and lymphocytes through costimulatory molecules and cytokines are essential for mounting an efficient immune response and controlling its pathogenic potential. Here we demonstrate the immunomodulatory capacity of Trypanosoma cruzi, the causative agent of Chagas' disease, through its ability to induce differential expression of costimulatory molecules and cytokines by monocytes and T cells. Costimulatory molecule and cytokine modulation was evaluated using cells from noninfected individuals and from patients with the asymptomatic indeterminate form and those with the severe cardiac clinical form of Chagas' disease. Our results show that while exposure of monocytes to live T. cruzi leads to an increase in the frequency of CD80(+) monocytes in all groups, it decreases both the frequency and intensity of CD86 expression by monocytes from patients with the cardiac form but not from those with the indeterminate form. Conversely, exposure of lymphocytes to monocytes infected with T. cruzi increased the surface expression of cytotoxic-T-lymphocyte-associated antigen 4 (CTLA-4) by T cells from indeterminate but not from cardiac patients, compared to that from control patients. These data suggest that T. cruzi induces a potentially down-regulatory environment in indeterminate subjects, which is associated with higher CD80 and CTLA-4 expression. To test the functional importance of this modulation, we evaluated the expression of cytokines after in vitro infection. Although exposure of lymphocytes to parasite-infected monocytes induced high expression of inflammatory and anti-inflammatory cytokines by T cells in all groups, indeterminate patients displayed a higher ratio of monocytes expressing interleukin 10 than tumor necrosis factor alpha following infection than did controls. These data show the ability of T. cruzi to actively change the expression of costimulatory molecules and cytokines, suggesting molecular mechanisms for the differential clinical evolution of human Chagas' disease.     

Antigen-pulsed epidermal Langerhans cells protect susceptible mice from infection with the intracellular parasite Leishmania major

Efficient vaccination against the parasite Leishmania major, the causative agent of human cutaneous leishmaniasis, requires the development of a resistance-promoting CD4⁺ -mediated Th1 response. Epidermal Langerhans cells (LC) are critically involved in the induction of the primary immune response to Leishmania infection. They are able to ingest the parasites, to express MHC class II molecules with extraordinarily long half-life and to activate naive L. major -specific Th cells. Considering these unique properties, we studied the capacity of LC to mediate resistance to L. major in vivo. A single i.v. application of LC that had been pulsed with L. major antigen in vitro induced the protection in susceptible BALB/c mice against subsequent challenges with L. major parasites. Resistance could neither be induced by unpulsed LC, nor by L. major antigen alone or by L. major -pulsed macrophages. Development of resistance was paralleled by a reduced parasite burden and by a shift of the cytokine expression towards a Th1-like pattern. In contrast, control mice developed a Th2 response. In vitro exposure of LC to L. major antigen induced the expression of IL-12 (p40) mRNA. In conclusion, our data demonstrate that LC are able to serve as a natural adjuvant and to induce a protective immune response to L. major infection. This effect is based on the initiation of a Th1-like response that is likely to be mediated by IL-12.     

GCSF receptor regulates antigen uptake and expression of cytokines and costimulatory molecules in dendritic cells

RNA interference (RNAi), a process that specifically silences target gene expression, is a powerful technique to modulate cellular functions. In this study, we identified two small interference RNA (siRNA) sequences that can specifically and efficiently silence the expression of the granulocyte colony-stimulating factor receptor (GCSF-R) gene and achieved stable knockdown of GCSF-R using pFIV lentivirus containing the GCSF-R siRNA. GCSF-R knockdown significantly reduces the expression of IL-lalpha, IL-lbeta, IL-6, IL-10, H-2Kb, I-Ab, CD80 and CD86, and increases PDL1 and PDL2 expression, while IL-12p35, TGFbeta, TNFalpha and CD40 expression is unaltered. Furthermore, GCSF-R knockdown significantly changes the endocytosis and micro-pinocytosis abilities as well as surface expression of antigens of DC2.4 cells.     

Vaccination with plasmacytoid dendritic cells induces protection against infection with Leishmania major in mice

DC-based vaccination against Leishmania major induces a parasite-specific Th1 response and long-lasting protective immunity in susceptible mice. Since distinct DC subsets have been proposed to direct the predominant development of either Th1 or Th2 cells, we analyzed the capability of plasmacytoid DC (pDC) to induce protection and elicit a Th1 response against L. major. Pulsing with L. major lysate induced the activation and maturation of semi-mature murine pDC that had been isolated from the spleen, as indicated by up-regulation of the co-stimulatory molecules CD86 and CD80, but did not enhance the level of IFN-alpha secretion by pDC. Vaccination of susceptible mice with L. major lysate-pulsed pDC induced highly effective T cell-mediated immunity against subsequent infection with L. major parasites. Surprisingly, the protection was not accompanied by a polarized Th1 cytokine profile. Co-activation of pDC with CpG-containing oligodeoxynucleotides, which has been shown to be critical for activating the protective potential of myeloid DC, was not required for the protective effect of L. major antigen-pulsed pDC. These findings demonstrate that antigen-loaded pDC are able to induce T cell-mediated protection against a parasite disease and that experimental leishmaniasis is a suitable model to elucidate the mechanisms underlying DC-based vaccination against infections.     

特发性血小板减少性紫癜共刺激分子表达的研究进展

特发性血小板减少性紫癜（ITP）是一种自身免疫性疾病,其发病机制尚未完全明确,目前已证实,ITP患者体内存在T、B淋巴细胞的异常活化和B淋巴细胞依赖Th细胞辅助而产生自身抗血小板抗体。在T、B淋巴细胞相互作用和产生自身抗体的病理过程中,CD80、CD86与其配体CD28、CTLA4结合及CD40与其配体CD40L相互作用提供的共刺激信号起了重要的作用。研究表明共刺激分子过度表达有可能激活自身反应性T淋巴细胞,导致自身免疫病的发生。     

GPIF对免疫损伤小鼠T淋巴细胞膜表面共刺激分子表达的影响

目的：分析羊胎盘免疫调节因子(GPIF)对BALB/c小鼠T淋巴细胞共刺激表面抗原分子表达及其细胞因子分泌的影响，探讨羊胎盘免疫调节因子免疫促进作用机理。方法: 60Coγ-ray辐射所致免疫抑制小鼠连续7 d腹腔注射GPIF，流式细胞分析术分析BALB/c小鼠脾细胞表达CD28+、CD152+单阳性细胞百分率，表达CD4+CD28+、CD8+CD28+、CD4+CD152+、CD8+CD152+双阳性细胞百分率；ELISA法检测小鼠血清IL-2、IFN-γ分泌水平。结果: 羊胎盘免疫调节因子显著提高免疫损伤小鼠脾淋巴细胞CD28+、CD4+CD28+、CD8+CD28+阳性细胞百分率(P<0.05，P<0.01)，降低CD152+、CD4+CD152+阳性细胞百分率(P<0.05，P<0.01)，提高小鼠血清IL-2、IFN-γ分泌水平(P<0.01)。结论: 羊胎盘免疫调节因子的免疫促进作用与其调节T淋巴细胞CD28、CD152共刺激分子通路的活化信号传递，降低T淋巴细胞的功能抑制，促进T淋巴细胞的活化有关。活化的T淋巴细胞分泌细胞因子IL-2、IFN-γ，参与细胞因子介导的免疫网络调节。     

Evaluation of differential gene expression in Leishmania major Friedlin procyclics and metacyclics using DNA microarray analysis

The various Leishmania species are flagellated protozoans, responsible for a wide spectrum of human diseases. The sequence of the L. major genome is nearing completion and a large proportion of the identified genes have yet to be ascribed functions. DNA microarrays containing PCR-amplified DNA from a random amplified genomic library of L. major Friedlin (LmjF) [Mol. Biochem. Parasitol. 113 (2001) 337] were hybridized with fluorescent probes made from L. major Friedlin RNA from five time-points during differentiation from procyclics to metacyclics. The data were normalized for background and probe intensity and the relative abundance of RNA for each spot was calculated. Almost 15% (1387/9282) of the DNAs showed statistically significant (P<0.01) changes in expression (1.1-5-fold) during the transition, with 1.16% (108) showing up-regulation at two or more time-points and 0.14% (13) showing down-regulation. Northern blot analyses of selected genes confirmed these results. These studies confirmed the stage-specific expression of several known genes, as well as identifying a number of novel genes that are up-regulated in either procyclics or metacyclics.     

小鼠可溶性CD83对树突状细胞表达共刺激分子和共刺激活性的影响

目的：研究可溶性小鼠CD83（mCD83）对树突状细胞（DC）表达共刺激分子及共刺激活性的影响。方法：克隆mCD83基因，构建mCD83胞外功能区与人IgG1αFc段融合基因的真核表达载体pmCD83-hIg，并在COS-7细胞中表达可溶性mCD83-hIg融合蛋白。采用ELISA、Western blot和RT-PCR技术检测mCD83-hIg融合基因在COS-7细胞中的表达。用mCD83-hIg处理小鼠DC细胞系（DC2．4）采用流式细胞术检测DC细胞周期、细胞凋亡和共刺激分子CD80、CD86的表达影响；采用混合白细胞培养试验，检测mCD83-hIg对DC2．4刺激同种异基因T细胞增殖及产生IL-2和IFN-γ的影响。结果：酶切和序列测定鉴定显示构建的真核表达载体完全正确；mCD83-hIg对DC2．4细胞周期和细胞凋亡无影响，但可下调DC2．4表面共刺激分子CD80和CD86的表达；mCD83-hIg处理过的DC2．4刺激同种异基因T细胞增殖及产生IL-2和IFN-γ的能力显著下降。结论：mCD83-hIg可抑制DC表达共刺激分子并下调DC共刺激活性，从而抑制同种异基因T细胞增殖和产生细胞因子。     

Fonsecaea pedrosoi infection induces differential modulation of costimulatory molecules and cytokines in monocytes from patients with severe and mild forms of chromoblastomycosis

The host defense mechanism in chromoblastomycosis has not been thoroughly investigated. It has been suggested that cell-mediated immunity in patients with long-standing chromoblastomycosis is somehow impaired. As a result, these individuals became unable to develop an efficient immune reaction. Many studies have shown that monocyte-derived macrophages exhibit critical activities in immunity to microorganisms. Moreover, the ability of cells from the monocytic lineage to process and present antigens, to produce cytokines, and to provide costimulatory signals confirms their pivotal role in the initiation of specific immune responses. In the present study, it was observed that monocytes from patients with a severe form of disease had a higher production of IL-10 and a lower expression of HLA-DR and costimulatory molecules when stimulated with specific antigen or LPS. Immune modulation with recombinant IL-12 or anti-IL-10 can restore the antigen-specific Th1-type immune response in chromoblastomycosis patients by up-regulating HLA-DR and costimulatory molecules in monocytes. Therefore, our data show that monocytes from patients with different clinical forms of chromoblastomycosis present distinct phenotypic and functional profiles. This observation suggests possible mechanisms that control the T cell response and influence their role in the development of pathology.     

Soluble mouse major histocompatibility complex class II molecules produced in Drosophila cells

We have exploited Drosophila melanogaster. Schneider cells and compatible inducible expression vectors to produce large amounts of secreted major histocompatibility complex (MHC) class II molecules (I-E^d). A simple two-step purification protocol was developed. In the first step, recombinant molecules were enriched using a monoclonal anti-class II antibody column followed by a nickel chelate column which further purified and concentrated the recombinant protein to several mg/ml. Characterization of the purified material indicates that the molecules are correctly assembled into αβ heterodimers. Further analysis shows that the recombinant MHC class II molecules are devoid of endogenous peptides and, therefore, homogenous peptide/MHC complexes could be prepared by adding exogenous I-E^d-specific peptides at slightly acidic pH. Upon peptide addition, molecules underwent a conformational change into a more compact form revealed by gel filtration analysis. In addition, the peptide/MHC complexes were biologically active. As little as 10 ng of these complexes coated on plastic from a 100 ng/ml solution were sufficient to trigger antigen-specific T cell hybridomas. These MHC class II molecules, together with various forms of soluble T cell receptor (TcR) proteins, provide valuable tools to analyze the molecular details of TcR/antigen recognition.     

Differential expression of costimulatory molecules in chronic inflammatory periodontal disease tissue

Although B cell activation and subsequent immunoglobulin production are the immunopathological features of chronic inflammatory periodontal disease, in situ expression of costimulatory molecules in humoral immunity has not been investigated. In the present study we examined the expression of CD40, CD40 ligand (CD40L), CD80, CD86, CD28 and cytolytic T lymphocyte-associated antigen-4 (CTLA-4) on lymphocytes immunohistochemically. Cryostat sections were prepared from the gingival tissue samples of 14 patients with moderate to advanced adult periodontitis. In vitro kinetics of the expression of CD40L and CTLA-4 by peripheral blood T cells and that of CD80 and CD86 by peripheral blood B cells were also investigated by flow cytometry. Positive percentage expression of CD40L, CD28 and CTLA-4, and CD40, CD80 and CD86 was calculated for the number of CD3⁺ and CD19⁺ cells, respectively. Flow cytometric analysis demonstrated that the expression of CD40L and CTLA-4 on T cells, and CD80 and CD86 on B cells of peripheral blood was up-regulated upon activation. While most T cells and B cells expressed CD28, and CD80 and CD86, respectively, in gingival tissues, the expression of CD40L and CTLA-4 was lower but highly variable between specimens. Furthermore, these two molecules seemed to be expressed reciprocally in the lesion. As both CD40L and CTLA-4 expression are induced transiently by stimulation, variability in the expression of the molecules may reflect immunological activities and participation in the regulation of B cell activation of the lesion.     

Comparison of the effects of Leishmania major or Leishmania donovani infection on macrophage gene expression

The intracellular parasite Leishmania causes a wide spectrum of human disease, ranging from self-resolving cutaneous lesions to fatal visceral disease, depending on the species of Leishmania involved. The mechanisms by which different Leishmania species cause different pathologies are largely unknown. We have addressed this question by comparing the gene expression profiles of bone marrow-derived macrophages infected with either Leishmania donovani or L. major promastigotes. We found that the two species had very similar effects on macrophage gene expression. Both species caused a small (<2.5-fold) but statistically significant repression of several hundred genes. In addition, both species strongly induced and repressed about 60 genes. Comparing the effects of the two species showed that only 26 genes were regulated differently by L. major as opposed to L. donovani, including those for metallothioneins 1 and 2, HSP70 and -72, CCL4, Gadd45β, Dsp1, matrix metalloprotease 13, T-cell death-associated gene 51 (Tdag51), RhoB, spermine/spermidine N1-acyl transferase 1 (SSAT), and Cox2. L. donovani-infected macrophages were also found to express higher levels of Cox2 protein and prostaglandin E synthase mRNA than L. major-infected macrophages. While both species have previously been shown to trigger prostaglandin E synthesis by bystander cells, this study suggests that infected macrophages themselves express prostaglandin E-synthesizing genes only in response to L. donovani.     

Glutathione depletion induces differential apoptosis in cells of mouse retina, in vivo

Oxidative stress affects numerous intracellular macromolecules, and may result in cell death unless precisely regulated. Unregulated oxidative stress can be controlled by various cellular defense mechanisms such as glutathione (GSH) which can critically counteract the damaging effects of oxidative stress in mammalian cells. We determined the effects of unregulated oxidative stress induced by GSH depletion on cells in mouse retina. Mice were intraperitoneally injected with buthionine sulphoximine (BSO) at 1.5 g/kg. After 0, 1, 4, and 7 days of BSO administration, retinas were excised and sections were subjected to GSH assay and terminal uridine deoxynucleotidyl nick end labeling (TUNEL) analysis. After 4 days of BSO administration, the number of TUNEL positive cells was significantly increased. However, after 7 days, TUNEL positive cells returned to the basal level. The retinal region most affected by the BSO treatment appeared to be the outer nuclear layer where the photoreceptor cells reside. Different from cells in other regions, retinal cells in the inner nuclear layer increased in their apoptosis even after the first day of BSO injection, and the increase was further potentiated after 4 days. Taken together, our studies suggested that GSH depletion may cause unregulated oxidative stress to the cells in the retina and indeed increased cell death in the retina. The cells in the inner nuclear layer seemed to be affected earlier than the cells in other layers of the retina. The GSH level in the retina may be a crucial therapeutic target in preventing blindness.     

重症肌无力患者外周血B7∶CD28/CTLA4共刺激分子表达的动态变化

目的研究重症肌无力(MG)患者B7∶CD28/CTLA4共刺激通路相关分子表达动态变化及其与MG发病的关系. 方法用流式细胞仪检测18例MG患者和16例健康对照者外周血单个核细胞(PBMC)在经PMA(佛波酯)+ionomycin(钙离子导入剂)刺激的0 h、6 h、24 h、48 h时B7-1、B7-2、CD28、CTLA4分子在CD4+ T细胞和CD8+ T细胞表面的表达. 结果 (1) 0 h,MG患者B7-1、B7-2分子总体表达增加,CD4+、CD8+ T细胞表面B7-1、B7-2的表达未见明显增加,PMA+ionomycin刺激后B7-1、B7-2在CD4+、CD8+ T细胞表面也无增加;(2) 0 h,CD28、CTLA4的表达增强,其中CD28+细胞的增多主要表现在CD4+ T细胞亚群,CTLA4的表达增强主要在CD8+ T细胞,在PMA+ionomycin激活后,CD28表达明显增强,持续到48 h都处于较高水平(与对照组相比P＜0.01),CTLA4表达出现短暂增强,6 h即达高峰,以后下降,与对照组相比无显著增强(P＞0.05). 结论 MG患者外周血中B7∶CD28/CTLA4通路共刺激相关分子表达增高,持续时间延长,检测共刺激分子的表达可反映机体的免疫激活状态,B7∶CD28/CTLA4通路在MG发病中可能起重要作用.     

Role of costimulatory molecules in autoimmunity

The precise mechanisms by which self-reactive T cells are activated and tolerance to self-antigens is broken are still not fully understood. It is widely accepted that dysregulation of costimulation contributes to the initiation and maintenance of autoimmunity due to activation of self-reactive T cells. Many of the costimulatory molecules thought to be essential for T cell activation have been identified. The CD28/CD152 (CTLA-4)-CD80/CD86 and CD40-CD154 (CD40 ligand) interactions are such receptor/ligand pairs that have been shown to be important in interactions between antigen-presenting cells and T cells. In vivo studies using costimulatory molecule-specific antibodies and fusion proteins and genetically manipulated animals have greatly increased our understanding of the role of these costimulatory molecules in the regulation of cellular processes that lead to autoimmunity and resultant autoimmune diseases.     

孕早期干预CD80/CD86协同刺激信号对自然流产模型免疫活性细胞协同刺激分子表达的影响

目的 :探讨孕早期干预协同刺激信号对自然流产模型孕鼠免疫活性细胞MHC Ⅱ类抗原和协同刺激分子的调控作用。方法 :建立自然流产模型组CBA×DBA 2和协同刺激信号干预组CBA×DBA 2 (CBA小鼠在孕 4天腹腔注射CD80及CD86mAb各 0 1mg)。分别于孕第 14天计数两组的胚胎吸收率 ,于孕第 9天采用流式细胞技术分析孕鼠脾细胞MHC Ⅱ类抗原与协同刺激分子CD80 (B7 1)、CD86 (B7 2 )、CD2 8和CD15 2 (CTLA 4 )的表达。结果 :孕早期干预协同刺激信号后 ,孕第 14天的胚胎吸收率显著下降 (P <0 0 5 ) ;孕第 9天免疫活性细胞CD80、CD86和CD2 8的表达显著下降 (P <0 0 1) ;CTLA 4的表达则显著升高 (P <0 0 5 ) ;而MHC Ⅱ类抗原的表达无显著改变 (P >0 0 5 )。结论 :孕早期体内干预协同刺激信号使免疫活性细胞协同刺激分子CD80、CD86、CD2 8表达下调和CTLA 4表达上调 ,及母胎界面Th2型免疫偏离 ,从而诱导系统性母 胎免疫耐受     

Effect of Pseudomonas aeruginosa exotoxin A on IFN-gamma synthesis: expression of costimulatory molecules on monocytes and activity of NK cells.

The aim of the study was (1) to evaluate the effect of Pseudomonas aeruginosa Exotoxin A (P-ExA) on the production of IFN-gamma in anti-CD3 induced human peripheral blood mononuclear cells (PBMC) and (2) to establish the effect of P-ExA on the IFN-gamma dependent cellular activities such as the expression of costimulatory molecules on monocytes and cytotoxicity of NK cells. The toxin in a high dose (100 ng/ml) inhibited IFN-gamma synthesis. Inhibitory effect of P-ExA was abolished by IL-1alpha which in a combination with P-ExA exerted a strong synergistic effect on IFN-gamma synthesis. Other monokines such as IL-1beta, IL-6, TNF-alpha neither reversed the inhibitory effect of P-ExA nor induced production of IFN-gamma. P-ExA also inhibited IFN-gamma-induced cellular events: (1) expression of costimulatory molecules on monocytes (CD80, CD86, ICAM-1, HLA-DR); (2) cytotoxic activity of NK cells. Inhibition of NK cells activity by P-ExA was not reversed by cytokines such as IL-2, IFN-alpha and TNF-alpha, which are known to enhance effector functions of NK cells. From these results we conclude that: (1) inhibition of IFN-gamma synthesis, as well as IFN-gamma-induced expression of costimulatory molecules and NK-cell effector functions may lead to suppression of specific and non-specific defense mechanisms, respectively, which are necessary for elimination of PA bacteria; (2) enhancement of IFN-gamma synthesis induced by P-ExA in a combination with IL-1alpha may cause harmful, Th1 cells dependent, inflammatory reactions of the host (septic shock, tissue damage) during infection with Pseudomonas aeruginosa.     

The costimulatory role of TIM molecules

Summary:  The T-cell immunoglobulin domain and mucin domain (TIM) family, including TIM-1, TIM-2, TIM-3, and TIM-4, is a relatively newly described group of molecules with a conserved structure and important immunological functions, including T-cell activation, induction of T-cell apoptosis and T-cell tolerance, and the clearance of apoptotic cells. TIM-1 costimulates T-cell activation and enhances cytokine production. In humans, TIM-1 also serves as a susceptibility gene for allergy and asthma. TIM-3, expressed on T cells and dendritic cells, regulates T-cell apoptosis and immune tolerance. By contrast, TIM-4, which is expressed primarily on antigen-presenting cells and which is a receptor for phosphatidylserine, regulates T-cell activation and tolerance, in part by mediating the uptake and engulfment of apoptotic cells. The TIM molecules thus have surprisingly broad activities affecting multiple aspects of immunology.