Expression of CD137 (4-1BB) on human follicular dendritic cells

Follicular dendritic cells (FDCs) are the antigen (Ag)-trapping accessory cells of the germinal centres (GCs), essential for the development of humoral immune responses and memory. FDCs reside in the microenvironment of secondary lymphoid tissue where Ag-activated B cells expand, and undergo isotype switching and affinity maturation prior to becoming memory B cells. In addition to delivering Ag, FDCs also provide potent nonspecific accessory signals to the B cells, which are important for the GC reaction. In this report, we show that human tonsilar FDCs express the costimulatory molecule CD137. Surface expression of CD137 on FDCs was confirmed by immunofluorescent labelling and fluorescence-activated cell sorter analysis. CD137 was also highly expressed by the human cell line HK, which displays many characteristics of in vivo FDCs. The interaction between B cells and FDCs is essential for the GC reactions, and our finding suggests that CD137 plays a role in FDC-regulated B-cell responses.     

Human 4-1BB regulates CD28 co-stimulation to promote Th1 cell responses

Our present study provides evidence that the 4-1BB signal is critical to CD28 co-stimulation in maintaining T cell activation when CD28 has been down-regulated because of repeated stimulation. The 4-1BB signal synergized with CD28 co-stimulation by lowering the threshold of anti-CD28 required to sustain proliferation and IL-2 production. The 4-1BB signal also modulated CD28-mediated cytokine profiles by markedly enhancing Th1 but suppressing Th2-type cytokine production. The 4-1BB signal generated Th1-type cells, as identified by intracellular IFN-γ production. IFN-γ induction was detected preferentially in 4-1BB-expressing cells, but not in those expressing CD30. 4-1BB and CD30 were induced in both CD4⁺ and CD8⁺ cells, but the location of the two molecules was mutually exclusive in each T cell subset. Our study suggests that the 4-1BB signal regulates CD28 co-stimulation in the targeted subset cells to favor Th1 development and maintain long-term cell growth.     

CD137(人4-1BB)在dhfr-CHO中的表达及活性研究

目的 :构建CD137真核高效表达系统 ,深入研究CD137及其配体在细胞信号转导中的作用。方法 :将构建有CD137全长cDNA序列的pCDNA3质粒 (CMV ILA SEN ,CIS)及pSV2 dhfr(含二氢叶酸还原酶基因 ) ,运用脂质体介导法共转染二氢叶酸还原酶缺陷的CHO细胞 (dhfr CHO) ;用G4 18筛选出阳性克隆 ;MTX压力选择系统诱导CD137在dhfr CHO细胞的高效表达 ;RT PCR、免疫细胞化学法及流式细胞术测定CD137的表达情况 ;3H TdR掺入法进行活性研究。结果 :CD137为膜型表达 ,CIS转化dhfr CHO细胞CD137表达率为 96 0 7% ;活性研究显示CD137膜蛋白轻度促进抗CD3单抗诱导的PBMC增殖。结论 :获得高效表达CD137的CHO细胞株 ,CD137膜蛋白促进抗CD3单抗诱导的PBMC增殖。     

Costimulation of human CD28- T cells by 4-1BB ligand

The T cell surface protein CD28 provides a critical costimulatory signal for T cell activation. With age, humans accumulate increasing numbers of CD28- T cells, and this loss of CD28 expression is exacerbated certain disease states, such as HIV infection, autoimmune conditions or cancer. It is unclear whether CD28- T cells represent terminally differentiated effector cells or whether they remain sensitive to costimulation by CD28-independent pathways. Here, we demonstrate that 4-1 BB ligand can costimulate human CD28- T cells, resulting in cell division, inflammatory cytokine production, increased perforin levels, enhancement of cytolytic effector function, as well as the up-regulation of the anti-apoptotic protein Bcl-X(L). Thus, human CD28- T cells can respond to costimulatory signals and as such become attractive targets for therapeutic intervention, particularly in chronic infectious and inflammatory diseases where large numbers of these cells accumulate.     

Involvement of 4-1BB (CD137)-4-1BBligand interaction in the modulation of CD4 T cell-mediated inflammatory colitis

4-1BB ligand (4-1BBL) expressed on antigen-presenting cells interacts with 4-1BB on activated T cells (especially CD8+ cells) and co-stimulates the latter to secrete cytokines and to proliferate. The role of 4-1BB-4-1BBL interaction was studied here in a model of colitis based on naive CD4+ T cell transfer to SCID mice, a disease model in which CD8 cells do not take part. We found that CD4+ T cells from 4-1BB-deficient mice, after transfer in SCID mice, proliferated more rapidly compared to wild-type CD4+ T cells. Mice reconstituted with naive CD4+ T cells from 4-1BB-deficient mice developed colitis, however, with a mixed Th1/Th2 response, in contrast to the Th1-type response in mice reconstituted with wild-type naive CD4+ T cells. Importantly, this altered cytokine response did not temper colitis severity. Although it has been reported previously that 4-1BB co-stimulation may contribute to regulatory T cell functioning, we found that CD4+CD25+ regulatory T cells from 4-1BB-deficient mice were perfectly able to prevent naive CD4+ T cell-induced colitis. In conclusion, our data provide evidence that 4-1BB-4-1BBL interaction modulates the effector CD4+ T cell-driven immune response and cytokine production in experimental colitis without affecting regulatory T cell function.     

4-1BB （CD137） Ligand Enhanced Anti-Tumor Immune Response against Mouse Forestomach Carcinoma In Vivo

Cancer occurrence and development has been demonstrated to be associated with escape from immune surveillance, and low eostimulatory molecules expression has been considered as one of the important reasons for cancer evading the immune system. 4-1BB （CD137） is a costimulatory molecule expressed on the surface of activated T cells. Interaction of 4-1BB with its natural ligand （4-1BBL） expressed on antigen presenting cells （APCs） has been shown to amplify T-cell mediated immunity. We therefore examined whether murine cancer cells expressing 4-1BBL could produce antitumor effects in inoculated mice. Mouse forestomach carcinoma （MFC） cells were transfected with 4-1BBL gene （MFC/4-1BBL）. The proliferation of the transduced cells in vitro was not different from that of parental cells. However, MFC/4-1BBL cells developed small tumors and induced higher cytotoxicity of tumor infiltration lymphocyte （TIL）. Production of cytokines （IFN-γ TNF-α and IL-2） in serum and cytotoxic T lymphocyte （CTL） activity of splenocytes from mice immunized with mitomycin C （MMC）-treated MFC/4-1BBL cells were significantly higher than that from mice immunized with MMC-treated parental MFC and MFC/ pMKITneo cells. These results suggest that modification of cancer cells with 4-1BBL gene can produce antitumor immune responses.     

Interfacing T-cell effector and regulatory function through CD137 (4-1BB) co-stimulation

Historically, co-stimulation has been regarded as a prerequisite for T-cell activation. A lack of co-stimulation results in peripheral T-cell tolerance, which manifests as unresponsiveness or death through apoptosis. Recent findings, however, suggest that eliciting co-stimulation can also induce tolerance. Reconciling these diametrically opposed results is certainly of academic importance but more importantly transcends basic immunology and impacts present and future clinical trials that are centered on modulating T-cell co-stimulation. This review will focus on CD137 (4-1BB) and propose a mechanism of action in which CD137-primed CD8 T cells express effector function and also inhibit CD4 T-cell activation. This model suggests that the same CD8 T cells possess antitumor effector function interfaced with regulatory capacity, which ultimately leads to concomitant inhibition of tumorigenesis and autoimmune disease.     

The promise of 4-1BB (CD137)-mediated immunomodulation and the immunotherapy of cancer

Summary: The continuing efforts in biomedical research to develop new therapies for cancer are entering an exciting new phase. Research over the past two to three decades has yielded a much more detailed understanding of the complexities of the cellular and molecular interactions involved in the generation and regulation of immune responses. We are also gaining insights into the mechanisms by which tumors evade or escape immune recognition and by which they become resistant to various existing chemotherapeutic and/or radiotherapeutic strategies. A clear conclusion that can be drawn from these studies is that effective treatments of cancer will become much more multifaceted and will include immunotherapeutic approaches. The identification and molecular cloning of genes encoding the receptors and ligands that play crucial roles in the generation and regulation of immune responses provides exciting new opportunities to induce and enhance effective endogenous immune responses to cancer. In this regard, the genes that comprise the tumor necrosis factor and tumor necrosis factor receptor superfamilies show particular promise. One receptor:ligand pair (4-1BB/CD137 and 4-1BBL/CD137L) is emerging as a target with important potential in its ability to enhance the generation of effective tumor-specific immune responses in situ . The results of the studies cited in this review highlight the potentials of 4-1BB-mediated immunotherapy.     

Combined CD137 (4-1BB) and adjuvant therapy generates a developing pool of peptide-specific CD8 memory T cells

In practice, vaccines should induce lasting and efficaciousT cell immunity without promoting deleterious pathological consequences.To accomplish this goal we immunized mice with ovalbumin peptide,polyinosinic–polycytidylic and anti-CD137. Vaccinatedmice retained a massive functional CD8 T cell memory pool inlymphoid and non-lymphoid tissues for >1 year. The memoryT cells clonally expanded, produced substantial amounts of IFN,and responded vigorously to vesicular stomatitis virus infection.To understand how the vaccine might function, we showed thatthe antigen-specific T cells must bear CD137 in order for optimalpriming to occur. Thus, anti-CD137 agonist mAb directly stimulatedpeptide-specific CD8 T cells and conditioned them to survive.In contrast, CD137-deficient CD8 T cells did not survive despiteCD137 expression by antigen presenting cells. Taken together,the data indicate that CD137 and adjuvant combined therapy isan efficacious vaccine strategy for immunization with non-replicatinginert antigen.     

High expression of OX40 (CD134) and 4-1BB (CD137) molecules on CD4+CD25high cells in children with type 1 diabetes

PurposeDespite the rapidly rising incidence of diabetes in children, with the highest rise in children < 5 years of age, data on mechanisms that trigger severe beta-cells damage are limited. The aim of the study was to assess the frequency of OX40 (CD134) or 4-1BB (CD137) positive cells in the peripheral blood of children with newly diagnosed type 1 diabetes (T1D) in comparison to healthy controls.Material/methodsThe study included 33 children (mean age 7.3 ± 5.4 years) with newly diagnosed T1D and 39 age-matched healthy controls. Separate analysis was performed in children < 5 years. Flow cytometric analysis was performed using the following markers: CD4, CD25, CD137, and CD134. Fasting C-peptide level was assessed as well.ResultsThe frequency of CD4⁺CD25^highOX40⁺ was higher in T1D children than in controls (median value 3.58% vs. 1.1%, respectively; p = 0.003). Moreover, T1D children had higher frequency of CD4⁺CD25^high4-1BB⁺ cells than healthy subjects (median value 5.76% vs. 3.74%, respectively; p = 0.037). A significant correlation was noted between the age of diabetic children and the C-peptide level (r = 0.54, 95% CI [0.19–0.77], p = 0.004). In comparison with age-matched controls, children < 5 years had higher frequency of CD4⁺CD25^highOX40⁺ (p = 0.004) and CD4⁺CD25^high4-1BB⁺ cells (p = 0.079).ConclusionsOur study showed higher frequency of both OX40 and 4-1BB positive cells in T1D children in comparison to controls. It seems that observed differences might be more pronounced in children < 5 years of age than in older subjects. Further clinical studies are needed to determine the age-related differences in the immune system, in the pathogenesis of T1D.     

Differential clonal expansion of CD4 and CD8 T cells in response to 4-1BB ligation: contribution of 4-1BB during inflammatory responses

Cell surface proteins of the tumor necrosis factor (TNF) family of receptors have been intimately involved in inducing T cell death. A feature of these family members that is less well studied is their ability to rescue T cells from apoptosis. One such member is 4-1BB; an activation induced surface receptor on CD4 and CD8 T cells. This study demonstrates that the costimulatory effects of 4-1BB, which was found to enhance clonal expansion, required cross-linking of the receptor. The survival of the activated CD8 T cells following expansion was not associated with an increase in Bcl-2 expression. Provided that 4-1BB signaling was present, the amplification of activated CD8 T cell growth in vivo was independent of CD28 ligation. In vivo clonal expansion of activated CD4 T cells, however, was not as responsive to 4-1BB cross-linking. Moreover, 4-1BB-induced expansion was comparable to that mediated by LPS which can incite multiple costimulatory signals. Furthermore, LPS-mediated growth and survival of superantigen (SAg) stimulated T cells appeared to be partially dependent on interactions between 4-1BB and 4-1BB ligand (4-1BBL).     

4-1BB (CD137) is required for rapid clearance of Listeria monocytogenes infection

4-1BB (CD137), a member of the tumor necrosis factor receptor superfamily, is a T-cell-costimulatory receptor that is expressed on activated T cells, dendritic cells, and NK cells. Little has been reported about its role in early host defense against bacterial infection. In this study, we report that 4-1BB-deficient (4-1BB(-/-)) mice are much more susceptible to Listeria monocytogenes (intracellular bacteria) infections than wild-type mice. Upon L. monocytogenes infection, 4-1BB(-/-) mice showed a lower survival rate, a higher bacterial burden in organs, and larger hepatic microabscesses than 4-1BB(+/+) mice. 4-1BB(-/-) mice also had impairment in clearance of bacteria from the bloodstream. Neutrophils from 4-1BB(+/+) mice constitutively expressed 4-1BB, which could be activated to induce intracellular Ca(2+) influx by ligation with anti-4-1BB antibody. On the other hand, neutrophils from 4-1BB(-/-) mice were defective in reactive oxygen species generation, phagocytic activities, and intracellular Ca(2+) mobilization. In addition, mice pretreated with anti-4-1BB monoclonal antibody were much more resistant to L. monocytogenes infection than control antibody-treated mice. Our results support the notion that 4-1BB may play a major role in host defense against intracellular pathogens through neutrophil activation.     

Functional expression of 4-1BB (CD137) in the inflammatory tissue in Crohn's disease

4-1BB ligand (L) expressed on antigen presenting cells (APC) interacts with 4-1BB, expressed on activated T cells and this interaction costimulates T cells to secrete cytokines and to proliferate. We investigated whether 4-1BB/4-1BBL interactions might be involved in the pathogenesis of Crohn's disease (CD). In immunohistochemistry, we found 4-1BB expression on lamina propria (LP) cells in inflamed and to a lesser extend in non-inflamed gut tissue from CD patients. mRNA levels for 4-1BB were also elevated in intestinal CD tissue. In contrast, only few 4-1BB-expressing cells were found in inflamed tissue from ulcerative colitis (UC) patients and almost no positive cells were found in control intestinal tissue. 4-1BB expression was better sustained on in vitro activated lamina propria T cells from CD patients compared to controls. Finally, agonistic anti-4-1BB antibody enhanced interferon-gamma (IFN-gamma) production and proliferation of lamina propria T cells from CD patients. Taken together, our data suggest that 4-1BB/4-1BBL interactions contribute to the persistence of gut inflammation in CD.     

Blockade of the 4-1BB (CD137)/4-1BBL and/or CD28/CD80/CD86 costimulatory pathways promotes corneal allograft survival in mice

To explore the roles of 4-1BB (CD137) and CD28 in corneal transplantation, we examined the effect of 4-1BB/4-1BB ligand (4-1BBL) and/or CD28/CD80/CD86 blockade on corneal allograft survival in mice. Allogeneic corneal transplantation was performed between two strains of wild-type (WT) mice, BALB/c and C57BL/6 (B6), and between BALB/c and B6 WT donors and various gene knockout (KO) recipients. Some of the WT graft recipients were treated intraperitoneally with agonistic anti-4-1BB or blocking anti-4-1BBL monoclonal antibody (mAb) on days 0, 2, 4 and 6 after transplantation. Transplanted eyes were observed over a 13-week period. Allogeneic grafts in control WT B6 and BALB/c mice treated with rat immunoglobulin G showed median survival times (MST) of 12 and 14 days, respectively. Allogeneic grafts in B6 WT recipients treated with anti-4-1BB mAb showed accelerated rejection, with an MST of 8 days. In contrast, allogeneic grafts in BALB/c 4-1BB/CD28 KO and B6 CD80/CD86 KO recipients had significantly prolonged graft survival times (MST, 52.5 days and 36 days, respectively). Treatment of WT recipients with anti-4-1BB mAb resulted in enhanced cellular proliferation in the mixed lymphocyte reaction and increased the numbers of CD4(+) CD8(+) T cells, and macrophages in the grafts, which correlated with decreased graft survival time, whereas transplant recipients with costimulatory receptor deletion showed longer graft survival times. These results suggest that the absence of receptors for the 4-1BB/4-1BBL and/or CD28/CD80/CD86 costimulatory pathways promotes corneal allograft survival, whereas triggering 4-1BB with an agonistic mAb enhances the rejection of corneal allografts.     

Expression of L-selectin (CD62L) discriminates Th1- and Th2-like cytokine-producing memory CD4+ T cells.

Human memory (CD45RO+) CD4+ T cells can be distinguished into two subpopulations on the basis of expression of the lymph node homing receptor, L-selectin (CD62L). In a prior study we showed that human L-selectin-positive memory T-helper (Th) cells promote the maturation of IgG- and IgA-producing cells by naive B cells. To further elucidate the contribution of memory CD4+ T cells to B-cell differentiation, human memory CD4+ T cells with or without L-selectin expression were evaluated for production of cytokines that participate in regulation of immunoglobulin production. It was found that L-selectin-positive human memory CD4+ T cells produce mainly interleukin (IL)-4 and IL-5, whereas L-selectin-negative CD4+ T cells produce mainly interferon-gamma (IFN-gamma). This profile of cytokine expression coincides with the profile that distinguishes Th1 and Th2 subsets. In contrast to the murine system, IL-10 production was similarly contributed by human L-selectin-positive and -negative memory CD4+ T-cell subpopulations. These results suggest that the human L-selectin-negative and -positive subpopulations of human memory CD4+ T cells contain Th1-like and Th2-like cytokine-producing cells, respectively.     

Interleukin-11 modulates Th1/Th2 cytokine production from activated CD4+ T cells.

Recombinant human interleukin-11 (rHuIL-11) is a pleiotropic cytokine with effects on multiple cell types. rHuIL-11 reduces activated macrophage activity and downregulates production of proinflammatory mediators, such as tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO). In vitro and in vivo, rHuIL-11 inhibits production of key immunostimulatory cytokines, including IL-12 and interferon-gamma (IFN-gamma). rHuIL-11 has recently demonstrated immunomodulatory activity to downregulate IFN-gamma production, increase IL-4 production, and reduce inflammatory tissue injury in a human psoriasis clinical trial. The cellular mechanisms of these effects are not fully elucidated. We demonstrate here that expression of gp130 and IL-11 receptor (IL-11R) alpha mRNA, components of the IL-11R complex, are detected in human and murine CD4(+) and CD8(+) lymphocytes, suggesting that rHuIL-11 can directly interact with T cells. In a cell culture model of murine T cell differentiation, rHuIL-11 acts to inhibit IL-2 production as well as IL-12-induced IFN-gamma production and enhances IL-4 and IL-10 production. rHuIL-11 had no effect on T cell proliferation. The ability of rHuIL-11 to modulate cytokine production from activated CD4(+) T cells provides a mechanism through which rHuIL-11 may ameliorate such inflammatory diseases as psoriasis.     

4-1BB (CD137) controls the clonal expansion and survival of CD8 T cells in vivo but does not contribute to the development of cytotoxicity

4-1BB is expressed on activated T cells. We analyzed the role of 4-1BB during the CD8 T cell response of OT-I TCR-transgenic T cells to ovalbumin. In vitro, blocking 4-1BB during peptide presentation reduced proliferation of naive CD8 T cells, but did not affect the generation of CTL. Using an in vivo adoptive transfer model, clonal expansion of CD8 T cells to whole protein in adjuvant was significantly reduced when 4-1BB was blocked, with 50-70% fewer CD8 T cells accumulating. This was due to a reduction in T cell division and to enhanced apoptosis of CD8 T cells that had undergone many divisions. T cells generated in the absence of 4-1BB were impaired in their ability to secrete IFN-gamma whereas CTL activity of the T cells that survived was unaffected. These findings demonstrate that 4-1BB contributes to clonal expansion, survival, and development of Tc1 cells when protein antigen is encountered by primary CD8 T cells in an inflammatory environment in vivo.     

Prostaglandin I2 analogs inhibit Th1 and Th2 effector cytokine production by CD4 T cells

An anti-inflammatory effect of PGI(2) has been suggested by increased inflammation in mice that are deficient in the PGI(2) receptor (IP) or in respiratory syncytial viral- or OVA-induced CD4 T cell-associated responses. To determine the mechanism of the anti-inflammatory effect, we hypothesized that PGI(2) analogs inhibit CD4 T cell effector cytokine production. To test this hypothesis, we activated purified CD4 T cells with anti-CD3 and anti-CD28 antibodies under Th1 and Th2 polarizing conditions for 4 days and restimulated the T cells with anti-CD3 in the presence of PGI(2) analogs for 2 days. We found that PGI(2) analogs (cicaprost and iloprost) inhibited the production of Th1 cytokines (IFN-gamma) and Th2 cytokines (IL-4, IL-10, and IL-13) in a dose-dependent pattern. The inhibitory effect was partially dependent on the IP receptor signaling and was correlated with elevated intracellular cAMP and down-regulated NF-kappaB activity. Pretreatment of the CD4 T cells with 8-bromoadenosine-3',5'-cyclic monophosphorothioate, Rp-isomer, to inhibit a key signaling molecule in the cAMP pathway, protein kinase A (PKA), attenuated the suppressive effect of PGI(2) analogs significantly, suggesting that PKA, in part, mediates the inhibition of the cytokine production. These data indicate that PGI(2) analogs have an immune-suppressive effect on previously activated and differentiated CD4 T cells in vitro and suggest that PGI(2) may have a similar function in vivo.     

TCR-independent CD137 (4-1BB) signaling promotes CD8+-exhausted T cell proliferation and terminal differentiation

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