Biomedical subjects

Jannie Borst

Publications and source records attributed to Jannie Borst.

18 recordsLinked to original sources

PubMed2006

CD27 contributes to the early systemic immune response to Mycobacterium tuberculosis infection but does not affect outcome.

The development of a strong Th1-mediated adaptive immune response is considered of main importance for host defense against the intracellular pathogen Mycobacterium tuberculosis. The induction of a cellular immune response is not only dependent on the engagement of the TCR but also requires co-stimulation. In order to study the role of the co-stimulatory molecule of the tumor necrosis factor receptor family member CD27 during murine M. tuberculosis infection, we intranasally infected wild-type (WT) and CD27 knockout (KO) mice with 10(5) colony-forming units M. tuberculosis. Whereas there were no differences in bacterial growth, inflammation and IFNgamma production by CD4+ and CD8+ lymphocytes in the lungs early after infection, the number of splenic CD8+ T cells producing the key Th1 cytokine IFNgamma was lower in CD27 KO mice than in WT mice. After 6 weeks, CD27 KO mice had 3.6-fold higher mycobacterial counts in their lungs and displayed more pulmonary inflammation and increased numbers of infiltrated leukocytes. Despite these differences early in infection, an equal number of WT and CD27 KO mice died during a 43-week observation period and lung bacterial loads and inflammation were comparable in the surviving animals. Our data suggest that CD27 does not contribute to the local IFNgamma-mediated response and long-term protection against M. tuberculosis.

Animals↗

PubMed2006

TRAIL enhances efficacy of radiotherapy in a p53 mutant, Bcl-2 overexpressing lymphoid malignancy.

BACKGROUND AND PURPOSE: Resistance to apoptosis is a contributing factor in the response to radiotherapy. Aim of this study was to evaluate whether TRAIL--in a soluble isoleucine zippered form--enhances the cytotoxic effect of irradiation on tumour cells with a blockade in the mitochondrial apoptosis route and/or a dysfunctional p53 pathway. MATERIALS AND METHODS: The p53 mutant human T acute lymphoblastic leukemia line Jurkat transduced with the Bcl-2 gene was used as model system in vitro and in a subcutaneous transplant setting in immunodeficient mice. Sensitivity to single and combined treatment was read out by apoptosis hallmarks and clonogenic survival in vitro, and by bioluminescence and palpation in vivo. RESULTS: Jurkat cells overexpressing Bcl-2 did not undergo apoptosis after irradiation, but the combination with TRAIL synergistically induced apoptosis without breaking mitochondrial resistance. TRAIL also reduced clonogenic survival after irradiation. In vivo, radiotherapy or TRAIL alone delayed tumour outgrowth, but combination treatment had the most profound effect. CONCLUSIONS: Isoleucine zippered TRAIL can strongly enhance the efficacy of tumour therapy with ionising radiation in an unfavourable setting of p53 mutation and Bcl-2 overexpression.

Animals↗

PubMed2006

Control of peripheral T cell survival: a delicate division of labor between cytokines and costimulatory molecules.

Throughout their life span, T lymphocytes are confronted with diverse and often extreme circumstances: they either are in a resting state or proliferate vigorously and find themselves in lymphoid organs, blood stream, or peripheral tissues. Under all these conditions, their survival depends on extracellular factors that counteract apoptotic cell death and sustain metabolism. In the different phases of T cell life and throughout the antigen-dependent T cell response, different cytokine receptors and costimulatory receptors provide the input to direct these processes, via intracellular signaling pathways that have been elucidated in significant detail.

Cell Death↗

PubMed2006

Immune stimulatory effects of CD70 override CD70-mediated immune cell apoptosis in rodent glioma models and confer long-lasting antiglioma immunity in vivo.

CD70 (CD27 ligand) promotes the expansion of primed lymphocytes by enhancing cell survival. Surprisingly, we previously observed that CD70 aberrantly expressed on human glioma cells promoted immune cell apoptosis and inhibited alloreactive lysis. Here we report that ectopic expression of CD70 in mouse glioma cells enhances apoptosis of T, B and NK cells in coculture, but nevertheless promotes glioma cell lysis by NK cells in vitro. In nude mice, CD70 expression in SMA-560 gliomas delays the glioma growth upon subcutaneous (s.c.) or intracerebral (i.c.) inoculation, suggesting a role for CD70/CD27-dependent NK cell activity in tumor surveillance. In syngeneic immunocompetent VM/Dk mice, CD70 allows the rejection of s.c. and i.c. implanted SMA-560 tumors. The tumorigenicity of CD70-expressing glioma cells is abrogated when TGF-beta signaling is blocked. Moreover, mice surviving the s.c. CD70 glioma challenge subsequently also reject wild-type glioma cells administered i.c. Similarly, CD70-expressing GL-261 gliomas are rejected in syngeneic C57BL/6 mice, while glioma growth is restored in C57BL/6 CD27(-/-) mice, suggesting that the CD70/CD27 interaction recruits a tumor-specific T-cell repertoire and induces tumor-specific memory. Altogether, these observations indicate that the net effect of aberrant CD70 expression in gliomas is immune stimulatory rather than immune paralytic and encourage its application in tumor immunotherapy.

Animals↗

PubMed2005

During viral infection of the respiratory tract, CD27, 4-1BB, and OX40 collectively determine formation of CD8+ memory T cells and their capacity for secondary expansion.

Independent studies have shown that CD27, 4-1BB, and OX40 can all promote survival of activated CD8+ T cells. We have therefore compared their impact on CD8+ memory T cell formation and responsiveness within one, physiologically relevant model system. Recombinant mice, selectively lacking input of one or two receptors, were challenged intranasally with influenza virus, and the immunodominant virus-specific CD8+ T cell response was quantified at priming and effector sites. Upon primary infection, CD27 and (to a lesser extent) 4-1BB made nonredundant contributions to accumulation of CD8+ virus-specific T cells in draining lymph nodes and lung, while OX40 had no effect. Interestingly though, in the memory response, accumulation of virus-specific CD8+ T cells in spleen and lung critically depended on all three receptor systems. This was explained by two observations: 1) CD27, 4-1BB, and OX40 were collectively responsible for generation of the same memory CD8+ T cell pool; 2) CD27, 4-1BB, and OX40 collectively determined the extent of secondary expansion, as shown by adoptive transfers with standardized numbers of memory cells. Surprisingly, wild-type CD8+ memory T cells expanded normally in primed OX40 ligand- or 4-1BB ligand-deficient mice. However, when wild-type memory cells were generated in OX40 ligand- or 4-1BB ligand-deficient mice, their secondary expansion was impaired. This provides the novel concept that stimulation of CD8+ T cells by OX40 and 4-1BB ligand during priming imprints into them the capacity for secondary expansion. Our data argue that ligand on dendritic cells and/or B cells may be critical for this.

Administration, Intranasal↗

PubMed2005

Virus-induced polyclonal B cell activation improves protective CTL memory via retained CD27 expression on memory CTL.

Different viruses elicit distinct phenotypes of memory cytotoxic T lymphocytes (CTL). This is reflected in differential expression of homing receptors and costimulatory molecules like CD27. Memory CTL retained CD27 following lymphocytic choriomeningitis virus (LCMV) infection, but not after immunization with recombinant vaccinia virus or tumor cells expressing LCMV glycoprotein. Stable CD27 expression on memory CTL required ligation by CD70 expressed on polyclonally activated B cells during the contraction phase. The functional consequence of CD27 expressed on virus-specific CTL was analyzed in CD27-deficient mice. LCMV infection of CD27(-/-) mice revealed that primary CTL activation and expansion as well as elimination of the virus were independent of CD27 expression. In contrast, ligation of CD27 on memory CTL upon secondary antigen encounter increased clonal expansion and improved protection against re-infection. This points to novel B cell-CTL interactions during viral infection and to a beneficial role of polyclonal B cell activation that represents a characteristic of murine LCMV, human immunodeficiency virus and human hepatitis B and C virus infection.

Animals↗

PubMed2005

CD27 and CD70 in T cell and B cell activation.

In vitro work has defined the TNF receptor family member CD27 as a T and B cell co-stimulatory molecule. Its activity is governed by the transient availability of its TNF-like ligand CD70 on lymphocytes and dendritic cells. Recent studies, enforcing or abrogating CD27 function by genetic or protein intervention in mouse models have revealed key contributions of the CD27-CD70 system to effector and memory T cell formation, which is probably based on improved cell survival. The stimulatory effects of CD27 on B cell function appear to oppose those of CD70, which also has a signaling role. Targeting CD27-CD70 for therapy is attractive but should take into account the fact that constitutive CD27 stimulation culminates in lethal immunodeficiency.

Animals↗

PubMed2004

Ubiquitin ligase activity of c-Cbl guides the epidermal growth factor receptor into clathrin-coated pits by two distinct modes of Eps15 recruitment.

We have demonstrated previously that c-Cbl requires the presence of a functional ubiquitin interacting motif (UIM) in Eps15 to mediate epidermal growth factor receptor (EGFR) endocytosis. Both the ubiquitin ligase activity of c-Cbl and the UIM of Eps15 were necessary for plasma membrane recruitment of Eps15 and entry of ligand-bound EGFR into coated pits and vesicles containing Eps15. This is consistent with a scenario in which ubiquitin moieties appended to activated EGFR complexes act as docking sites for Eps15 and thereby recruit receptors into clathrin coated pits. Here, we have investigated which additional structural features of c-Cbl are required for this process. We find that c-Cbl can guide ligand-bound EGFR into the Eps15 internalization route by two distinct mechanisms. These are either dependent on the phosphotyrosine binding domain of c-Cbl that directly binds to the EGFR or on the region C-terminal of the Ring finger, which allows for indirect binding to an alternative site on the receptor. No strict requirement exists for either ubiquitin modified EGFR or the Cbl binding ubiquitination substrate CIN85 as docking site for the UIM of Eps15. Only in the phosphotyrosine binding-dependent pathway, the EGFR is ubiquitinated and may serve as a site of recruitment for Eps15. Only in this pathway, Eps15 is tyrosine-phosphorylated, but this appears unrelated to its capacity to participate in EGFR internalization.

Adaptor Proteins, Signal Transducing↗

PubMed2004

c-Cbl directs EGF receptors into an endocytic pathway that involves the ubiquitin-interacting motif of Eps15.

c-Cbl associates with the activated EGF receptor before endocytosis. We here reveal that the capacity of c-Cbl to promote receptor internalization depends on its ubiquitin ligase activity, which functionally connects the EGF receptor to Eps15, a mediator of clathrin-coated pit formation. EGF-induced phosphorylation of Eps15, as well as recruitment of Eps15 to the plasma membrane and its co-localization with the EGF receptor in endosomes required the ubiquitin ligase activity of c-Cbl. This suggested that ubiquitin provides a direct or indirect link between the receptor and Eps15. Indeed, EGF-induced redistribution of Eps15 to the plasma membrane and endosomes depended on its ubiquitin-interacting motif. Upon over-expression, the ubiquitin-interacting motif abrogated the capacity of c-Cbl to promote EGF receptor endocytosis and only allowed receptor internalization via a route that lacked Eps15. Our findings disclose a novel function for the c-Cbl ubiquitin ligase and identify ubiquitin as a module that directs the EGF receptor into an endocytic pathway involving Eps15.

Adaptor Proteins, Signal Transducing↗

PubMed2004

CD27 is acquired by primed B cells at the centroblast stage and promotes germinal center formation.

Studies on human B cells have featured CD27 as a marker and mediator of the B cell response. We have studied CD27 expression and function on B cells in the mouse. We find that B cells acquire CD27 at the centroblast stage and lose it progressively upon further differentiation. It is not a marker for somatically mutated B cells and is present at very low frequency on memory B cells. Enrichment of CD27 among centroblasts and the presence of its ligand CD70 on occasional T and B cells in or near germinal centers (GCs) suggested a role for CD27/CD70 interactions in clonal B cell expansion. Accordingly, GC formation in response to influenza virus infection was delayed in CD27 knockout mice. CD27 deficiency did not affect somatic hypermutation or serum levels of virus-specific IgM, IgG, and IgA attained in primary and recall responses. Adoptive transfer of T and B cells into CD27/CD28(-/-) mice revealed that CD27 promotes GC formation and consequent IgG production by two distinct mechanisms. Stimulation of CD27 on B cells by CD28(+) Th cells accelerates GC formation, most likely by promoting centroblast expansion. In addition, CD27 on T cells can partially substitute for CD28 in supporting GC formation.

Adoptive Transfer↗

PubMed2004

Requirement for aspartate-cleaved bid in apoptosis signaling by DNA-damaging anti-cancer regimens.

Lymphoid malignancies can escape from DNA-damaging anti-cancer drugs and gamma-radiation by blocking apoptosis-signaling pathways. How these regimens induce apoptosis is incompletely defined, especially in cells with nonfunctional p53. We report here that the BH3-only Bcl-2 family member Bid is required for mitochondrial permeabilization and apoptosis induction by etoposide and gamma-radiation in p53 mutant T leukemic cells. Bid is not transcriptionally up-regulated in response to these stimuli but is activated by cleavage on aspartate residues 60 and/or 75, which are the targets of caspase-8 and granzyme B. Bid activity is not inhibitable by c-Flip(L), CrmA, or dominant negative caspase-9 and therefore is independent of inducer caspase activation by death receptors or the mitochondria. Caspase-2, which has been implicated as inducer caspase in DNA damage pathways, appeared to be processed in response to etoposide and gamma-radiation but downstream of caspase-9. Knock down of caspase-2 by short interfering RNA further excluded its role in Bid activation by DNA damage. Caspase-2 was implicated in the death receptor pathway however, where it contributed to effector caspase processing downstream of inducer caspases. Granzyme B-specific serpins could not block DNA damage-induced apoptosis, excluding a role for granzyme B in the generation of active Bid. We conclude that Bid, cleaved by an undefined aspartate-specific protease, can be a key mediator of the apoptotic response to DNA-damaging anticancer regimens.

Animals↗

PubMed2003

CD27 promotes survival of activated T cells and complements CD28 in generation and establishment of the effector T cell pool.

CD27, like CD28, acts in concert with the T cell receptor to support T cell expansion. Using CD27(-/-) mice, we have shown earlier that CD27 determines the magnitude of primary and memory T cell responses to influenza virus. Here, we have examined the relative contributions of CD27 and CD28 to generation of the virus-specific effector T cell pool and its establishment at the site of infection (the lung), using CD27(-/-), CD28(-/-), and CD27/CD28(-/-) mice. We find that primary and memory CD8+ T cell responses to influenza virus are dependent on the collective contribution of both receptors. In the primary response, CD27 and CD28 impact to a similar extent on expansion of virus-specific T cells in draining lymph nodes. CD27 is the principle determinant for accumulation of virus-specific T cells in the lung because it can sustain this response in CD28(-/-) mice. Unlike CD28, CD27 does not affect cell cycle activity, but promotes survival of activated T cells throughout successive rounds of division at the site of priming and may do so at the site of infection as well. CD27 was found to rescue CD28(-/-) T cells from death at the onset of division, explaining its capacity to support a T cell response in absence of CD28.

Adoptive Transfer↗

PubMed2003

Ceramide: second messenger or modulator of membrane structure and dynamics?

The physiological role of ceramide formation in response to cell stimulation remains controversial. Here, we emphasize that ceramide is not a priori an apoptotic signalling molecule. Recent work points out that the conversion of sphingomyelin into ceramide can play a membrane structural (physical) role, with consequences for membrane microdomain function, membrane vesiculation, fusion/fission and vesicular trafficking. These processes contribute to cellular signalling. At the Golgi, ceramide takes part in a metabolic flux towards sphingomyelin, diacylglycerol and glycosphingolipids, which drives lipid raft formation and vesicular transport towards the plasma membrane. At the cell surface, receptor clustering in lipid rafts and the formation of endosomes can be facilitated by transient ceramide formation. Also, signalling towards mitochondria may involve glycosphingolipid-containing vesicles. Ceramide may affect the permeability of the mitochondrial outer membrane and the release of cytochrome c. In the effector phase of apoptosis, the breakdown of plasma membrane sphingomyelin to ceramide is a consequence of lipid scrambling, and may regulate apoptotic body formation. Thus ceramide formation serves many different functions at distinct locations in the cell. Given the limited capacity for spontaneous intracellular diffusion or membrane flip-flop of natural ceramide species, the topology and membrane sidedness of ceramide generation are crucial determinants of its impact on cell biology.

Animals↗

PubMed2003

Expression of the murine CD27 ligand CD70 in vitro and in vivo.

The interaction between TNFR family member CD27 and its ligand CD70 promotes lymphocyte expansion and effector cell formation. In humans, control of CD27 function is partly regulated by the restricted expression of CD70. We used newly developed mAbs to characterize murine (m) CD70 expression in vitro and in vivo. On resting lymphocytes and immature dendritic cells (DC), mCD70 is absent. In vitro, Ag receptor triggering induced mCD70 mRNA in T cells, but cell surface protein expression was very low. Activated B cells synthesized much higher levels of mCD70 mRNA than activated T cells and clearly expressed mCD70 at the cell surface. mCD70 cell surface expression could also be induced on the DC line D1 and on in vitro-generated murine DC upon maturation. In lymphoid organs of naive mice, virtually no mCD70-expressing cells were found, with exception of cells in the thymic medulla, which may be epithelial in origin. However, after intranasal infection with influenza virus, lung-infiltrating T cells and T and B cells in draining lymph nodes expressed mCD70 according to immunohistology. In such activated lymphocytes, mCD70 protein is largely retained intracellularly. Plasma membrane expression of mCD70 was only detectable by flow cytometry on a small proportion of lung-infiltrating T cells and peaked at the height of the primary response. Thus, expression of CD70 in the mouse is highly regulated at the transcriptional and posttranslational level. This most likely serves to limit excessive effector cell formation after antigenic stimulation.

Animals↗

PubMed2002

Lethal T cell immunodeficiency induced by chronic costimulation via CD27-CD70 interactions.

It has been proposed that HIV-1, in addition to directly infecting and killing CD4+ T cells, causes T cell dysfunction and T cell loss by chronic immune activation. We analyzed the effects of chronic immune activation in mice that constitutively expressed CD70, the ligand for the tumor necrosis factor receptor family member CD27, on B cells. CD70 transgenic (CD70 Tg) mice showed a progressive conversion of naive T cells into effector-memory cells, which culminated in the depletion of naive T cells from lymph nodes and spleen. T cell changes depended on continuous CD27-CD70 interactions and T cell antigen receptor stimulation. Despite this hyperactive immune system, CD70 Tg mice died aged 6-8 months from Pneumocystis carinii infection, a hallmark of T cell immunodeficiency. Thus, persistent delivery of costimulatory signals via CD27-CD70 interactions, as may occur during chronic active viral infections, can exhaust the T cell pool and is sufficient to induce lethal immunodeficiency.

Animals↗

PubMed2002

c-Cbl is involved in Met signaling in B cells and mediates hepatocyte growth factor-induced receptor ubiquitination.

Hepatocyte growth factor/scatter factor (HGF) and its receptor tyrosine kinase Met are key regulators of epithelial motility and morphogenesis. Recent studies indicate that the HGF/Met pathway also plays a role in B cell differentiation, whereas uncontrolled Met signaling may lead to B cell neoplasia. These observations prompted us to explore HGF/Met signaling in B cells. In this study, we demonstrate that HGF induces strong tyrosine phosphorylation of the proto-oncogene product c-Cbl in B cells and increases Cbl association with the Src family tyrosine kinases Fyn and Lyn, as well as with phosphatidylinositol-3 kinase and CrkL. In addition, we demonstrate that c-Cbl mediates HGF-induced ubiquitination of Met. This requires the juxtamembrane tyrosine Y1001 (Y2) of Met, but not the multifunctional docking site (Y14/15) or any additional C-terminal tyrosine residues (Y13-16). In contrast to wild-type c-Cbl, the transforming mutants v-Cbl and 70Z/3 Cbl, which lack the ubiquitin ligase RING finger domain, suppress Met ubiquitination. Our findings identify c-Cbl as a negative regulator of HGF/Met signaling in B cells, mediating ubiquitination and, consequently, proteosomal degradation of Met, and suggest a role for Cbl in Met-mediated tumorigenesis.

Adaptor Proteins, Signal Transducing↗

PubMed2002

TRAIL receptor and CD95 signal to mitochondria via FADD, caspase-8/10, Bid, and Bax but differentially regulate events downstream from truncated Bid.

The death receptor ligand TRAIL arouses much interest for clinical application. We found that TRAIL receptor could induce cytochrome c (Cyt c) release from mitochondria in cells that failed to respond to CD95. Therefore, we examined whether these two closely related death receptors use different intermediates to convey the apoptotic signal to mitochondria. Dominant negative FADD, FLIP(L), or a Bid mutant lacking cleavage sites for caspase-8/10 completely inhibited Cyt c release in response to either receptor. Depletion of Bid from TRAIL- or CD95-activated cytosols blocked their capacity to mediate Cyt c release from mitochondria in vitro, whereas Bax depletion reduced it. We conclude that FADD, caspase-8/10, and caspase-cleaved Bid are required for TRAIL receptor and CD95 signaling to mitochondria, whereas Bax is a common accessory. In vitro, caspase-8 treatment of cytosol from CD95-resistant cells permitted generation of truncated Bid and its association with mitochondria. However, this cytosol impaired the ability of truncated Bid to liberate Cyt c from exogenous mitochondria. We conclude that the TRAIL receptor can bypass or neutralize the activity of cytosolic factor that blocks truncated Bid function. This may benefit the capacity of TRAIL to break apoptosis resistance in tumor cells.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Bcl-2 family member Bfl-1/A1 sequesters truncated bid to inhibit is collaboration with pro-apoptotic Bak or Bax.

Following caspase-8 mediated cleavage, a carboxyl-terminal fragment of the BH3 domain-only Bcl-2 family member Bid transmits the apoptotic signal from death receptors to mitochondria. In a screen for possible regulators of Bid, we defined Bfl-1/A1 as a potent Bid interacting protein. Bfl-1 is an anti-apoptotic Bcl-2 family member, whose preferential expression in hematopoietic cells and endothelium is controlled by inflammatory stimuli. Its mechanism of action is unknown. We find that Bfl-1 associates with both full-length Bid and truncated (t)Bid, via the Bid BH3 domain. Cellular expression of Bfl-1 confers protection against CD95- and Trail receptor-induced cytochrome c release. In vitro assays, using purified mitochondria and recombinant proteins, demonstrate that Bfl-1 binds full-length Bid, but does not interfere with its processing by caspase-8, or with its mitochondrial association. Confocal microscopy supports that Bfl-1, which at least in part constitutively localizes to mitochondria, does not impede tBid translocation. However, Bfl-1 remains tightly and selectively bound to tBid and blocks collaboration between tBid and Bax or Bak in the plane of the mitochondrial membrane, thereby preventing mitochondrial apoptotic activation. Lack of demonstrable interaction between Bfl-1 and Bak or Bax in the mitochondrial membrane suggests that Bfl-1 generally prevents the formation of a pro-apoptotic complex by sequestering BH3 domain-only proteins.

Animals↗