Cloning and characterization of mouse IL-22 binding protein

Interleukin-22 (IL-22), a member of IL-10 family, plays some important roles in immune response through activation of the STAT 3 signal transduction pathway. Two types of IL-22-binding receptor have been discovered, a membrane-bound receptor and a soluble receptor, both encoded by different genes. IL-22 may be involved in inflammatory processes specifically regulated by soluble receptors. By screening a mouse genomic library for a human IL-22 binding protein homologue, we identified the mouse genomic clone of IL-22 binding protein. Its coding sequence was verified and isolated by RT-PCR. The gene encodes a protein of 230 amino acids that share 67.1% amino-acid sequence identity with human IL-22 binding protein. We designated this receptor 'mouse IL-22 binding protein' (mIL-22BP). mIL-22BP could be upregulated by LPS stimulation in mouse monocytes. mIL-22BP binds to mouse and human IL-22 and neutralizes STAT3 activation induced by both cytokines in human and rat hepatoma cell lines. Treating B cells with mouse IL-22 induces production of reactive oxygen species, which mIL-22BP blocks.     

糖基化磷脂酰肌醇修饰的小鼠IL-21瘤苗抗肿瘤效应及其机制初探

目的 构建糖基化磷脂酰肌醇(glycosyl phosphafidylinositol,GPI)修饰的小鼠IL-21瘤苗,并对此瘤苗的抗肿瘤效应及其机制作初步探讨.方法 通过重叠PCR方法获得IL-21-GPI融合基因并将其插入空载体pcDNA3.1.将鉴定过的重组载体以脂质体法转染B16F10细胞制成瘤苗,细胞间接免疫荧光法及流式细胞仪检测转染瘤细胞膜表面IL-21的表达,通过对小鼠脾细胞的增殖作用鉴定表达的IL-21的生物学活性.将瘤苗接种小鼠后,通过观察小鼠肿瘤体积和生存率分析瘤苗的抗瘤性,并检测了瘤苗免疫鼠的细胞免疫活性.结果 正确构建了pcDNA3.1/IL-21-GPI重组载体,膜表达的IL-21有良好的生物学活性,制备的瘤苗能发挥抗肿瘤效应,其机制与免疫鼠细胞免疫活性增强有关.结论 成功构建了具有抗肿瘤活性的GPI修饰的IL-21瘤苗,为其进一步抗肿瘤免疫治疗研究奠定了基础.     

CD4(+) regulatory T cells in autoimmunity and allergy

Regulatory T cells (also referred to as suppressor T cells) are important components of the homeostasis of the immune system, as impaired regulatory T cell activity can cause autoimmune diseases and atopy. It is now clear that the phrase 'regulatory T cells' encompasses more than one cell type. For instance, CD4(+)CD25(+) regulatory T cells have received attention due to their immunosuppressive properties in vitro and in vivo, but in several instances it has been shown that CD4(+)CD25(-) T cell populations also contain potent regulatory activity. Recent progress in the field of regulatory T cells includes the discovery of the role of two tumor necrosis factor receptor (TNFR) family members (GITR and TRANCE-R/RANK) in Treg biology, the improved understanding of the role of co-stimulatory molecules and cytokines IL-10 and IL-2 in the induction and function of Tregs, and the generation of CD25(+) and CD25(-) regulatory T cells in vivo through high-avidity T cell receptor interactions.     

The construction of a new oncolytic herpes simplex virus expressing murine interleukin-15 with gene-editing technology

The treatment of tumors with oncolytic viruses is an important cancer immunotherapy strategy. Interleukin-15 (IL-15) can enhance the antitumor effect of natural killer cells and T cells. An oncolytic herpes simplex type II virus (oHSV2-mIL-15CherryFP) expressing mouse IL-15 was constructed using the CRISPR/Cas9 system, and its antitumor activity in vitro and in vivo was evaluated. In vitro, the mouse interleukin-15 (mIL-15) present in the culture supernatant expressed by oHSV2-mIL-15CherryFP was able to enhance the killing of CT26-GFP tumor cells by T cells. In addition, the intratumoral injection of oHSV2-mIL-15CherryFP inhibited tumor growth in the CT26-iRFP and BGC823-iRFP model. These results indicate that the use of oncolytic herpes simplex virus expressing IL-15 may be a potential therapeutic strategy in tumor immunotherapy.     

逆转录病毒介导的小鼠IL-23基因在小鼠结肠癌细胞中的表达及其抗肿瘤活性

目的：获得表达小鼠IL-23(mIL-23)基因的小鼠结肠癌细胞株。方法：应用逆转录病毒载体，将mIL-23基因导入小鼠结肠癌细胞株Colon26，经G418筛选后获得表达mIL-23的阳性细胞克隆(Colon26／IL-23)。用PCR和RT—PCR检测目的基因的表达，用ELISA法检测mIL-23的产生及mIL-23诱导的小鼠脾细胞IFN-γ的产生，用MTT比色法检测Colon26／IL-23细胞和Colon26细胞的体外增殖，将Colon26／IL-23细胞接种于BALB／c小鼠的右侧背部皮下，观察其致瘤性结果：建立了可表达mIL-23基因的小鼠结肠癌细胞株。分泌至培养上清中的IL-23，可诱导小鼠脾细胞产生IFN-γ在体外Colon26／IL-23细胞的生长与Colon26细胞无明显不同，但其在体内的致瘤性下降，具有抗瘤作用。结论：Colon6／IL-23细胞可分泌IL-23并证明其具有抗瘤活性。     

CD80融合蛋白修饰的H22细胞激发抗肿瘤免疫

目的 探讨CD80-IgG1 Fc段融合蛋白修饰的H22细胞对淋巴细胞抗肿瘤免疫的影响.方法 应用福建省临床免疫研究所构建的CD80-IgG1 Fc段融合蛋白,修饰小鼠肝癌细胞株H22细胞,用流式细胞术检测修饰的H22细胞上CD80的表达.将修饰的H22细胞与小鼠脾细胞悬液混合后进行培养,分别应用MTT比色法、乳酸脱氢酶释放试验,检测经CD80-IgG1Fc段融合蛋白修饰的H22细胞对脾淋巴细胞增殖及其细胞毒性的影响.结果 CD80-IgG1 Fc段融合蛋白可有效地结合于H22细胞膜上(P＜0.05),融合蛋白修饰的H22细胞可明显刺激脾淋巴细胞活化增殖并增强CTL的细胞毒活性(P＜0.05).结论 CD80在抗肿瘤免疫中起着重要作用,用CD80-IgG1Fc段融合蛋白修饰的H22细胞能明显增强淋巴细胞的特异性抗肿瘤免疫,为CD80用于肿瘤免疫治疗的研究提供了实验依据,为下一步体内免疫治疗肿瘤奠定了基础.     

The role of the combination of IL-2 and TGF-beta or IL-10 in the generation and function of CD4+ CD25+ and CD8+ regulatory T cell subsets

Recently, considerable attention has been focused on thymus-derived CD4+ regulatory T cells that constitutively express CD25 and have a contact-dependent, cytokine-independent mechanism in vitro. However, peripheral CD4+ and CD8+ T cells can also be induced to become regulatory T cells. Here we review our studies using the combination of IL-2 and transforming growth factor beta (TGF-beta) to generate regulatory T cell subsets ex vivo, and the work of others using IL-10 to induce suppressive activity. Under certain conditions, the autocrine effects of TGF-beta and IL-10 induce peripheral T cells to produce immunosuppressive levels of each of these cytokines. This effect of TGF-beta is IL-2 dependent. Under other conditions IL-2 and TGF-beta can induce CD4+ cells to develop potent contact-dependent, cytokine-independent regulatory activity. At present, there is considerable confusion concerning the mechanism of action of CD4+ CD25+ cells because cytokine-producing regulatory T cells generated in the periphery can express CD25 and other markers displayed by naturally occurring, thymus-derived regulatory T cells. We, therefore, propose a nomenclature that identifies thymus-derived and peripheral regulatory cells, and that also differentiates T regulatory cells from T helper cells. Because T regulatory cells broadly control T helper cell reactivity, the mechanisms that control regulatory cell function are also reviewed. Finally, the potential use of regulatory T cells generated ex vivo as an adoptive immunotherapy for certain autoimmune diseases, to prevent organ graft rejection, or to prevent pathologic host responses to infectious agents is discussed.     

Elevated Expression of Transmembrane IL-15 in Immune Cells Correlates with the Development of Murine Lupus: a Potential Target for Immunotherapy Against SLE

Presentation in trans by the Interleukin-15 receptor α chain (IL-15Rα) has been suggested as the main mechanism for IL-15 anchoring to the cell surface, but it is also evident that IL-15 can exist as a transmembrane protein. We herein demonstrate that replacement of the first 41 residues of human IL-15 (hIL-15) with Ig κ chain leader sequence resulted in secretion of most of the recombinant hIL-15 expressed in transfectant cells, thus identifying the transmembrane region of IL-15. A fusion protein (hIL-15Rα-Fc) between the extracellular domain of hIL-15Rα and the Fc fragment of IgG1 was prepared and shown to be able to bind with transmembrane IL-15 (tmIL-15). The level of tmIL-15 expression in macrophages, activated T cells and B cells from 6-month-old BXSB male mice, an animal model for systemic lupus erythematosus (SLE), was significantly increased compared with that from BXSB females or young males. In addition, hIL-15Rα-Fc was able to block the T cell stimulating and anti-apoptotic effect of the tmIL-15-positive BXSB macrophages in vitro . Intravenous administration of hIL-15Rα-Fc reduced the titre of autoantibodies against dsDNA and also proteinuria in aged BXSB males, implying that neutralization of IL-15 activity in vivo may be an effective way of treating SLE.     

Marking IL-4-producing cells by knock-in of the IL-4 gene

IL-4 is a cytokine which can be expressed by a number of cell types including Th2 cells, mast cells and a population of CD4+ NK1.1+ NK T cells. Although phenotypic markers exist for identifying each of these cell types, there is at present no known cell surface marker common to all IL-4-producing cells. Using gene targeting in embryonic stem cells, we have modified the IL-4 locus by knock-in of a transmembrane domain to generate mice that express a membrane-bound form of IL-4 (mIL-4). Flow cytometry using an IL-4-specific mAb allowed the detection of IL-secreting Th2 cells, mast cells and NK T cells from mIL-4 mice. Furthermore, the analysis of immune responses in mIL-4 mice following immunization with anti-CD3 and anti-IgD has allowed us to identify distinct subpopulations of IL-4-producing NK T cells. Thus, the expression of IL-4 in a membrane-bound form provides a novel method for the identification and characterization of IL-4-producing cells.     

通过维持微环境IL－2水平抑制肿瘤形成

为研究肿瘤微环境中ＩＬ－２对肿瘤生长的抑制效应，用转基因方法，将携带ｍＩＬ－２ｃＤＮＡ基因的牛乳头瘤病毒载体（ＢＣＭＧ）转染小鼠Ｂ１６瘤细胞，获稳定持久分泌ｍＩＬ－２的Ｂ１６细胞株（ｍＩＬ－２＋Ｂ１６）。动物实验结果显示：ｍＩＬ－２＋Ｂ１６细胞的致瘤性明显下降，但体外生长率与其亲代Ｂ１６细胞相比较无区别。用ｍＩＬ－２＋Ｂ１６细胞诱导的小鼠腹腔渗出细胞（ＰＥＣ）对ＹＡＣ－１靶细胞和Ｂ１６靶细胞的体外杀伤能力比对照组ＰＥＣ（Ｂ１６诱导的ＰＥＣ）高一倍以上（Ｐ＜０．０１）。表明提高微环境中的ＩＬ－２水平能提高抗肿瘤免疫细胞对肿瘤细胞的杀伤能力，从而抑制肿瘤的形成。     

Induction of autoantibodies to different interleukin-2 allotypes

We report the development of an in vivo system to induce the generation, and study the potential role, of autoantibodies to the lymphokine interleukin-2 (IL-2). To elicit IL-2 autoantibodies, mice were immunized with purified fusion proteins containing the N-terminal region of different IL-2 allotypes, where major changes have been observed. This part of the IL-2 molecule includes a conserved sequence with an essential residue for interacting with the beta-chain of the heterotrimeric IL-2 receptor. Mice bearing an RF IL-2 allotype, immunized with several N-terminal IL-2 fusion proteins, produced IgG antibodies against Mus musculus, C57BL/6, Mus spretus and the self molecule RF IL-2, but there were large differences among then in reactivity. These N-terminal IL-2 immunogens break the maintenance of self tolerance possibly by the introduction of new T cell epitopes on self IL-2. The immunized mice developed a complex set of immunopathologies such as splenomegaly, haemolytic anaemia and lymphoadenopathy with a long latency period after the last immunization. These pathologies resembled those described for IL-2-deficient mice (IL-2(-/-)) and mice injected with anti-IL-2 receptor alpha-antibody. Human IL-2 autoantibodies have been detected in several immune-affected situations and therefore this model would be of interest to study the potential evolution of these autoantibodies in relation to immunopathology. The production of these autoantibodies against conserved epitopes of mouse IL-2 may facilitate studies on the structural homologies between different IL-2 allotypes and from various species, and could be applied to other cytokines.     

Targeting of CD45 protein tyrosine phosphatase activity to lipid microdomains on the T cell surface inhibits TCR signaling

CD45, a transmembrane protein tyrosine phosphatase (PTP), can either positively or negatively regulate Src-family protein tyrosine kinase (PTK) activity in vivo. It is proposed that TCR-initiated signaling requires the segregation of PTP activities from the engaged TCR, based upon the differential membrane compartmentalization on the T cell surface. To test the importance of CD45 exclusion from lipid microdomains for proper TCR signaling, a chimeric molecule was generated by fusing the CD45 cytoplasmic region, which contains the PTP domains, to the amino-terminal 12 amino acids of Lck, which target Lck to lipid microdomains. Using 3A9 T lymphocyte hybridoma (3A9H) cells whose TCR recognizes hen egg-white lysozyme (HEL), Lck-CD45 expression resulted in its targeting to lipid microdomains. The 3A9H cells expressing Lck-CD45 were reduced in their responses to HEL or co-cross-linking of CD3 and CD4, as assessed by IL-2 production and Ca(2+) mobilization. Src-family PTK activity associated with lipid microdomains was also decreased. These results suggest that the segregation of CD45 from proximal TCR signaling components is necessary for TCR signaling and that the targeting of CD45 PTP activity to lipid microdomains on the T cell surface results in decreased sensitivity of TCR-mediated signaling.     

IFN-gamma is the only anti-rotavirus cytokine found after in vitro stimulation of memory CD4+ T cells from mice immunized with a chimeric VP6 protein

CD4+ T cells are the only lymphocytes required for protection of mice against rotavirus shedding after mucosal immunization with chimeric VP6 (MBP::VP6) and the adjuvant LT(R192G). One possible effector of protection is CD4+ T-cell cytokines. To determine if memory CD4+ T cells of immunized mice produce cytokines with direct anti-rotavirus activity, an in vitro infection model was developed using mouse CMT-93 cells and rhesus rotavirus (RRV). Spleen and lamina propria (LP) cells, as well as purified splenic CD4T cells obtained after intranasal immunization of BALB/c mice with MBP::VP6/LT(R192G) released large quantities of two cytokines (IL-17 and IFN-gamma) into cell supernatants when stimulated with MBP::VP6. Production of these same cytokines is rapidly upregulated in intestinal lymphocytes after rotavirus inoculation of immunized mice. IL-17 pretreatment of CMT-93 cells had no effect on subsequent RRV replication, but IFN-gamma was the most potent inhibitor within a panel of nine cytokines tested. Supernatants obtained after in vitro stimulation of splenic CD4+ T cells of immunized mice had high levels of anti-RRV activity and their pretreatment with mAb against IFN-gamma caused essentially complete loss of activity. Thus, IFN-gamma was the only cytokine identified in stimulated CD4+ T cells from immunized mice that directly inhibited rotavirus replication.     

Local delivery of recombinant adenovirus expressing hepatitis B virus X protein and interleukin-12 results in antitumor effects via inhibition of hepatoma cell growth and intervention of tumor microenvironment

Hepatocellular carcinoma (HCC) is a typical hypervascular tumor. Our previous studies have demonstrated that hepatitis B virus X protein (HBx) was able to inhibit the growth of HCC cells via inducing apoptosis and inhibiting tumor angiogenesis. Interleukin-12 (IL-12) is a disulfide-linked heterodimeric cytokine with potent immunostimulatory activity and anti-angiogenic properties. In this study, to further investigate the regulatory effect of IL-12 on HBx-mediated intervention of hepatoma microenvironment especially on intervention of neovessels and immune microenvironment, we constructed the recombinant adenovirus expressing HBx and mouse IL-12 named Ad-HBx-mIL-12. HBx-mIL-12 could effectively suppress tumor growth and induce apoptosis in vivo. Moreover, treatment with Ad-HBx-mIL-12 not only induced a massive accumulation of immune cells (CD8(+) T leukocytes, macrophages and dendritic cells) in tumors in situ, also apparently reduced the number of angiogenic blood vessels within tumor tissues. These results suggest that HBx-mIL-12 can not only induce cell cycle arrest and apoptosis in HCC cells, but also effectively shift the tumor microenvironment from pro-oncogenic to antitumor through recruitment of immune cells and inhibiting stromal cell growth, such as vascular endothelial cells.     

The membrane-bound but not the soluble form of human Fas ligand is responsible for its inflammatory activity

The ectopic expression of Fas ligand (FasL/CD95L) in tissues or tumors induces neutrophil infiltration and the destruction of the tissues or the rejection of tumors. It has been suggested that the infiltrated neutrophils are responsible for the latter phenomena. FasL is synthesized as a type II transmembrane protein, and soluble FasL is produced by a proteolytic mechanism from the membrane-bound form. We previously demonstrated that uncleavable membrane-bound FasL of mice induces IL-1 beta release from inflammatory cells, and suggested that the IL-1 beta enhances neutrophil infiltration. However, recent papers reported that human soluble FasL is directly chemoattractive to neutrophils in vitro and proposed that the soluble form of FasL is responsible for its inflammatory activity. Therefore, in this report, we investigated which form is responsible for the inflammatory activities of human FasL. We produced tumor cell lines expressing one or both forms of human FasL. Cells expressing both forms or only the membrane-bound form of FasL induced neutrophil infiltration when transplanted into the peritoneal cavity of syngeneic mice, while cells expressing only the soluble form did not. Purified soluble FasL failed to induce neutrophil infiltration in vivo. IL-1 beta release from inflammatory peritoneal exudate and acceleration of tumor rejection were also mediated by membrane-bound but not soluble FasL. These results indicate that the membrane-bound form of FasL is primarily responsible for its inflammatory activity.     

Cytokine production from murine CD4 and CD8 cells after mannan-MUC1 immunization.

Immunotherapy with oxidized mannan-MUC1 fusion protein (M-FP) leads to a T1 immune response characterized by the generation of cytotoxic T lymphocytes (CTL), few antibodies, secretion of interleukin-2 (IL-2), IL-12, and interferon-gamma and tumor protection. Immunotherapy with reduced M-FP or fusion protein (FP) alone leads to a T2 immune response characterized by the generation of MUC1 antibodies, few CTL, IL-4 secretion, and no tumor protection. In these studies, cytokine production from T cells was measured from cultures containing whole spleens. We now report the cytokine secretion patterns from spleen cells separated into CD4+ and CD8+ T cells obtained from mice immunized with either oxidized M-FP, reduced M-FP or FP, or the simultaneous administration of oxidized M-FP and FP. Immunization with oxidized M-FP led to the secretion of T1 cytokines from CD8+ T cells (IL-2, IFN-gamma, and tumor necrosis factor-alpha [TNF-alpha]) and from CD4+ T cells (IL-2 and IFN-gamma). IL-12 production, presumably from activated macrophages, was observed in CD8+ but not CD4+ cultures. Immunization with either reduced M-FP or FP led to the secretion of predominantly T2 cytokines from CD4+ T cells (IL-4 and IL-10) and IL-2 production in both CD4+ and CD8+ T cell cultures. The simultaneous immunization of both oxidized M-FP and FP led to the production of both T1 and T2 cytokines from CD8+ T cells (IL-2, IFN-gamma, and TNF-alpha) and CD4+ cells (IL-2, IFN-gamma, IL-4, and IL-10) and IL-12 production in CD8+ cultures that is, both types of immune responses could occur together. The results demonstrate that the cellular immune response observed in oxidized M-FP-immunized mice is indeed dependent on the T1 cytokine profile secreted by CD8+ T cells, and the simultaneous production of both T1 and T2 cytokines is not cross-inhibitory.     

Expression, purification and identification of recombinant mouse interleukin 21 protein in E. coli

Interleukin 21 （IL-21） is a novel type I cytokine that is significantly homologous to IL-2, IL-4 and IL-15. Its receptor complex contains γc chain which is also a component of receptors for IL-2, IL-4, IL-7, IL-9 and IL-15, so there may be overlapping or relevancies in their biological functions. IL-21 is capable of co-stimulating mature T cells, B cells, NK cells, and of stimulating CD16 expression on the surface of NK cells to induce ADCC in innate immune response. It can also strengthen the anti-tumor effect of the cellular immunity, especially v/a enhancing the activities of NK and antigen specific CTL cells. Thus, IL-21 is a potential useful therapeutic molecule for immunotherapy of malignancies, by eliciting innate and adaptive anti-tumor immune responses in tumor-bearing hosts. In order to study the biological functions of IL-21, we constructed a mIL-21 prokaryotic expression plasmid and expressed the recombinant mIL-21 protein in E. coli in present study. The recombinant plasmid pET28a/mIL-21 with a carboxyl terminal His-tag was subcloned from the pcDNA3.1/mIL-21 and expressed in E. coli. The induced protein was detected by SDS-PAGE, and identified by Western-blot assay with anti-mIL-21 antibody. The recombinant protein was purified v/a Ni^＋ affinity chromatography, and renatured with GSH/GSSG system. Our mouse T cell proliferation experiment showed that the recombinant mIL-21 protein could enhance the mouse T cell proliferation either by itself alone or in the presence of Con A.     

IL-4 inhibits VLA-4 expression on Tc1 cells resulting in poor tumor infiltration and reduced therapy benefit

We and others have previously demonstrated that IL-4-dependent Tc2 are inferior to Tc1-effector CD8+ T cells in regulating tumor progression in vivo. This functional disparity relates, in part, to the comparatively poor ability of Tc2 to migrate into diseased tissues. We now show that IL-4 treatment of committed Tc1 cells promotes the selective loss in the expression of very-late antigen (VLA)-4, without impacting the Tc1 cytokine production profile, cytotoxic activity, or expression of alternate cell surface markers. Down-regulation of VLA-4 expression on Tc1 cells was unique to treatment with IL-4 (i.e. Tc1IL-4) and did not occur in the presence of the Type-2 cytokine IL-13 or the regulatory cytokines IL-10 or TGF-beta. Notably, the inhibitory effects of IL-4 on Tc1 expression of VLA-4 could be blocked by the presence of IL-12, but not IFN-gamma. Predictably, Tc1IL-4 (but not Tc1 control) cells adhere poorly to plate-bound VCAM-1-Fc fusion protein and fail to be co-stimulated by VCAM-1 in vitro. They were also markedly impaired in their ability to traffic into intracranial melanoma lesions after adoptive transfer, yielding inferior therapeutic benefit to tumor-bearing mice. These results suggest a novel suppressive mechanism for IL-4 that limits Tc1 efficacy via preventing their recruitment into tumors.