DNA vaccination with asparaginyl endopeptidase (Sm32) from the parasite Schistosoma mansoni: anti-fecundity effect induced in mice

DNA-based vaccine technology was used to induce an immune response in mice against a schistosome cysteine proteinase, asparaginyl endopeptidase (Sm32). The cDNA coding for Sm32 was cloned in a mammalian expression vector under control of the CMV promoter/enhancer and expressed for the first time in transfected mammalian cells as well as in mice immunized with the Sm32-encoding DNA construct. These mice developed antibodies which recognized the native protein not only in homogenates of Schistosoma mansoni worms but also in the gut on cryostat sections of the parasites. This DNA vaccine led to an anti-fecundity effect: female worms of a challenge infection produced 37% less eggs than those growing in naïve mice. The results suggest that Sm32 may be a candidate antigen for the generation of an anti-pathology vaccine against schistosomes.

T-cell immunity in the induction and maintenance of a tumour dormant state

We conclude from animal tumour model studies that T cell immunity can play an essential role in the induction and maintenance of tumour dormancy. Evidence was found in tumour dormancy situations for active control of proliferating tumour cells by CD8 memory T cells leading to a long-term balance in the bone marrow between low numbers of tumour cells and immunological memory. In breast cancer patients, too, the bone marrow may represent a privileged compartment for tumour dormancy and immunological memory. Upon restimulation with tumour antigen pulsed autologous dendritic cells, bone marrow-derived memory T cells from cancer patients could be shown to exist and to become activated into potent anti-tumour effector cells.

Antitumor effects of Newcastle Disease Virus in vivo: local versus systemic effects

Newcastle Disease Virus (NDV) has interesting anti-neoplastic and pleiotropic immune stimulatory properties. The virus preferentially replicates in and kills tumor cells and appears to be safe and to varying degrees effective in phase II-clinical studies in the US and in Europe. Here we have compared various lytic and non-lytic strains of NDV with regard to their antitumor effects after local or systemic application. As tumor models we used human metastatic melanoma xenotransplants in nude mice and murine metastatic colon carcinoma (CT26), renal carcinoma (Renca) and lymphoma (ESb) cell lines. Intra or peri-tumoral application of NDV or NDV infected tumor cells showed more pronounced antitumor activity than systemic application even when in the latter case much higher dose ranges were used. In the CT26 colon carcinoma model the non-lytic strain Ulster showed stronger antitumor activity than the lytic strain 73T. In the human MeWo melanoma xentransplant model strong antitumor bystander effects were observed by 20% admixture of melanoma cells pre-infected in vitro with NDV (either strain Ulster or Italien). Virus therapy of pre-established human melanomas by intra-tumoral injection of NDV was effective with the lytic strain Italien but not with the non-lytic strain Ulster. Systemic anti-metastatic effects were never observed with NDV alone in contrast to previous results obtained with NDV modified tumor vaccines.

Inhibition of nitric-oxide-mediated apoptosis in Jurkat leukemia cells despite cytochrome c release

We have recently shown that nitric-oxide (NO)-induced apoptosis in Jurkat human leukemia cells requires degradation of mitochondria phospholipid cardiolipin, cytochrome c release, and activation of caspase-9 and caspase-3. Moreover, an inhibitor of lipid peroxidation, Trolox, suppressed apoptosis in Jurkat cells induced by NO donor glycerol trinitrate. Here we demonstrate that this antiapoptotic effect of Trolox occurred despite massive release of the mitochondrial protein cytochrome c into the cytosol and mitochondrial damage. Incubation with Trolox caused a profound reduction of intracellular ATP concentration in Jurkat cells treated by NO. Trolox prevented cardiolipin degradation and caused its accumulation in Jurkat cells. Furthermore, Trolox markedly downregulated the NO-mediated activation of caspase-9 and caspase-3. Caspase-9 is known to be activated by released cytochrome c and together with caspase-3 is considered the most proximal to mitochondria. Our results suggest that the targets of the antiapoptotic effect of Trolox are located downstream of the mitochondria and that caspase activation and subsequent apoptosis could be blocked even in the presence of cytochrome c released from the mitochondria.

Enrichment of memory T cells and other profound immunological changes in the bone marrow from untreated breast cancer patients

Previous studies with animal tumors showed that bone marrow (BM) is a privileged site where potentially lethal tumor cells are controlled in a dormant state by the immune system. Here, we investigated BM of breast cancer patients with respect to tumor cell content, immune activation status and memory T-cell content. BM-derived cells from primary operated breast cancer patients (n = 90) were compared with those from healthy donors (n = 10) and also with cells from respective blood samples. Cytokeratin 19-positive tumor cells were detected by nested polymerase chain reaction. Three-color flow cytometry was used to identify numbers and activation state of T cells, natural killer (NK) cells, monocytes/macrophages and subsets by a panel of monoclonal antibodies (mAbs). The proportion of memory T cells among the CD4 and CD8 T cells was much higher in BM of cancer patients than in healthy donors (p < 0.001). The extent of memory T-cell increase was related to the size of the primary tumor. Patient-derived BM memory CD8 T cells could be shown to contain specific HLA-A2/Her-2/neu(369-377) tetramer binding cells. Patients with disseminated tumor cells in their BM had more memory CD4 T cells and more CD56(+) CD8(+) cells than patients with tumor cell-negative BM. Only some of the immunological changes seen in BM samples of cancer patients were also detectable in peripheral blood samples. Our hypothesis that BM is a special compartment for immunological memory and tumor dormancy is supported by the above findings. The overall results reveal that BM is a valuable additional compartment for immune diagnosis in pathological conditions and possibly for follow-up treatment strategies.

Therapy of human tumors in NOD/SCID mice with patient-derived reactivated memory T cells from bone marrow

In an analysis of 84 primary-operated breast cancer patients and 11 healthy donors, we found that the bone marrow of most patients contained memory T cells with specificity for tumor-associated antigens. Patients' bone marrow and peripheral blood contained CD8+ T cells that specifically bound HLA/peptide tetramers. In short-term culture with autologous dendritic cells pre-pulsed with tumor lysates, patients' memory T cells from bone marrow (but not peripheral blood) could be specifically reactivated to interferon-gamma-producing and cytotoxic effector cells. A single transfer of restimulated bone-marrow T cells into NOD/SCID mice caused regression of autologous tumor xenotransplants associated with infiltration by human T cells and tumor-cell apoptosis and necrosis. T cells from peripheral blood showed much lower anti-tumor reactivity. Our findings reveal an innate, specific recognition of breast cancer antigens and point to a possible novel cancer therapy using patients' bone-marrow-derived memory T cells.

Dissection of tumor and host cells from metastasized organs for testing gene expression directly ex vivo

The interaction between tumor and host cells determines to a large extent the outcome, namely tumor growth and progression toward metastases or tumor arrest, dormancy, or rejection. Most of the studies published so far on interactions of tumor cells and host cells were made in vitro and dealt with aspects such as cell adhesion, proliferation, invasiveness, cytotoxicity, or cytokine production. As the microenvironment in tissue culture differs in many respects from that in vivo, new approaches for in vivo studies of tumor-host cell interactions is of utmost importance in cancer research. To elucidate the metastatic phenotype, approaches have been made to relate, for instance, cell surface molecules expressed on the tumor cell lines from tissue culture to their propensity to generate metastases in vivo (1). Several authors have reported that certain steps of the metastatic cascade are rate limiting (2-6). To produce metastases, tumor cells must complete each of the sequential steps in the pathogenesis of cancer metastasis. Each discrete step appears to depend on the interaction between tumor cells and multiple host factors (i.e., the microenvironment of the tumor) and to be regulated by transient or permanent changes in multiple genes at the level of DNA, RNA, or protein. On this background, the need for comprehensive in vivo/ex vivo studies on tumor-host interactions and their kinetics in relevant model systems becomes obvious.

[Anti-tumor vaccination]

Five year survival rates are presented for 32 primary operated breast cancer patients who were postoperatively treated with an optimal dose of autologous NDV-modified tumor vaccine. Their overall survival and their recurrent-free survival was significantly better than that of 31 comparable breast cancer patients treated simultaneously with a suboptimal dose of the same type of vaccine. The concept, development and mechanism of action of this vaccine are als commented on.

Breaking tolerance to a tumor-associated viral superantigen as a basis for graft-versus-leukemia reactivity

A major goal in tumor immunotherapy consists of breaking potential tumor-specific T-cell unresponsiveness (tolerance), which may explain tumor growth in cancer patients. We report that immunological tolerance to a tumor-associated viral superantigen (SAg) is overcome in a mouse lymphoma model by transfer of allogeneic T cells expressing SAg-reactive Vbeta6 T-cell receptor chains. Surprisingly, upon contact with SAg-expressing lymphoma cells, Vbeta6 T cells became activated rather than tolerized (as reported previously). They also developed SAg-specific cytotoxic T-lymphocyte activity and secreted IL-2 and IFN-gamma. The grafted T cells infiltrated liver metastases, formed close contact with SAg-expressing tumor cells, and caused significant graft-vs. -leukemia (GvL) effects. Selection for tumor resistance among the progeny from a cross between SAg-negative donor and SAg- positive recipient strains revealed a strict correlation between loss of the endogenous SAg tolerogen, rescue of Vbeta6 T cells from SAg-mediated deletion, and leukemia resistance. These findings suggest that immune responses to SAg can be exploited to break tolerance and augment immune responses to tumors.

Functional and in situ evidence for nitric oxide production driven by CD40-CD40L interactions in graft-versus-leukemia reactivity

In a murine tumor model, complete tumor remission is achievable at even advanced metastasized stages by transfer of immune T cells from donor B10.D2 (H-2d, Mls(b)) into tumor-bearing DBA/2 (H-2d, Mls(a)) mice. We showed previously that this graft-versus-leukemia (GvL) effect is dependent on synergistic interactions of transferred CD4+ and CD8+ T cells with host sialoadhesin (SER)-positive macrophages. We now show that the CD40-CD40L (CD154) interaction is involved in the induction of inducible nitric oxide synthase (iNOS) expression during adoptive immunotherapy (ADI). We demonstrate that during ADI, the level of CD40 expression in the liver becomes significantly augmented in comparison to livers of tumor-bearing, untreated animals. CD40 expression is found mostly on SER+ macrophages and to a lesser extent on dendritic cells (DCs). In GvL animals, more SER+ macrophages express iNOS than untreated animals. iNOS expressing cells are found in close proximity to apoptotic cells, at early time points of the therapy in areas of metastasis, and at late stages around portal veins, where CD4+ and CD8+ T lymphocytes form clusters with SER+ macrophages. Blocking of CD40L in vivo at days 5 and 20, when all iNOS+ cells express CD40, leads to significantly reduced CD40 and iNOS expression as well as to a marked inhibition of the therapeutic effect. These data provide functional and in situ evidence that the increased CD40 and iNOS expression observed during ADI contribute to the eradication of liver metastases and to the clearance of donor lymphocytes from the liver.

Newcastle disease virus activates macrophages for anti-tumor activity

Newcastle Disease Virus (NDV), an agent with interesting immune stimulatory and anti-tumor activity, was investigated for its capacity to activate anti-tumor activity in murine macrophages in vitro and in vivo. Direct macrophage activation was seen under a variety of experimental conditions using two different strains of NDV, different sources of macrophages (spleen and peritoneum) and different strains of mice (DBA/2, C57BL/6, 615). Various macrophage enzymes (ADA, iNOS, lysozyme, acid phosphatase) became upregulated and anti-tumor effector molecules such as nitric oxide (NO) and TNF-alpha were found in the supernatant. NDV activated macrophages performed anti-tumor activity in vitro such as anti-tumor cytostasis and anti-tumor cytotoxicity. The cytotoxic anti-tumor activity was broad and active against all tumor lines tested including mammary carcinoma, lung carcinoma, mastocytoma and immune escape variants (lymphoma). Macrophage activation via BCG/LPS also caused a broad range anti-tumor cytotoxic activity while activation via mixed lymphocyte culture conditioned medium had restricted anti-tumor activity. Anti-tumor activity of NDV activated macrophages could be transfered in vivo. Transfer of macrophages which had not been appropriately activated exerted either no effect or a tumor growth augmenting effect. Repeated intravenous transfer of NDV activated macrophages exerted a significant suppressive effect on pulmonary metastases in a mammary carcinoma tumor model as well as in a lung carcinoma model. Taken together these results demonstrate that NDV can strongly activate macrophages to perform anti-tumor activities in vitro and in vivo.

Newcastle disease virus infection induces B7-1/B7-2-independent T-cell costimulatory activity in human melanoma cells

Viral oncolysates of Newcastle disease virus (NDV) have been widely used for the treatment of malignant melanoma. Apparently, this nononcogenic and apathogenic paramyxovirus can alter the immunogenicity of tumor cells. To determine the influence of NDV infection on a tumor-specific T-cell response on a functional level, we used autologous primary melanoma cells infected with the NDV-strain Ulster. Therefore, melanoma cells and tumor-infiltrating lymphocytes were prepared from a freshly resected tumor, and tumor-infiltrating lymphocytes were subjected to limited dilution cloning. Proliferation assays of the T-helper cell clone sTS3 (CD4+) showed that the T-cell clone was rendered nonreactive against its autologous major histocompatibility complex II+, B7-1/B7-2- melanoma SMS, even remaining unresponsive to subsequent stimulation by interleukin-2. NDV infection of the SMS melanoma cell line not only completely restored the proliferative response of sTS3 to SMS, comparable with stimulation by cross-linking of anti-CD3/anti-CD28 monoclonal antibodies, but also inhibited the induction of anergy. Electrophoretic mobility shift assays of sTS3 cell lysates revealed the induction of the CD28-responsive complex by coincubation with NDV-infected melanoma cells. Because the induction of this complex of nuclear proteins shows specificity for the activation of the CD28 pathway but functional B7-1/B7-2 expression was not detectable on SMS melanoma cells at any timepoint, we propose the induction of a costimulatory factor different from B7 by NDV viral proteins.

Newcastle disease virus activates macrophages for anti-tumor activity

Newcastle Disease Virus (NDV), an agent with interesting immune stimulatory and anti-tumor activity, was investigated for its capacity to activate anti-tumor activity in murine macrophages in vitro and in vivo. Direct macrophage activation was seen under a variety of experimental conditions using two different strains of NDV, different sources of macrophages (spleen and peritoneum) and different strains of mice (DBA/2, C57BL/6, 615). Various macrophage enzymes (ADA, iNOS, lysozyme, acid phosphatase) became upregulated and anti-tumor effector molecules such as nitric oxide (NO) and TNF-alpha were found in the supernatant. NDV activated macrophages performed anti-tumor activity in vitro such as anti-tumor cytostasis and anti-tumor cytotoxicity. The cytotoxic anti-tumor activity was broad and active against all tumor lines tested including mammary carcinoma, lung carcinoma, mastocytoma and immune escape variants (lymphoma). Macrophage activation via BCG/LPS also caused a broad range anti-tumor cytotoxic activity while activation via mixed lymphocyte culture conditioned medium had restricted anti-tumor activity. Anti-tumor activity of NDV activated macrophages could be transfered in vivo. Transfer of macrophages which had not been appropriately activated exerted either no effect or a tumor growth augmenting effect. Repeated intravenous transfer of NDV activated macrophages exerted a significant suppressive effect on pulmonary metastases in a mammary carcinoma tumor model as well as in a lung carcinoma model. Taken together these results demonstrate that NDV can strongly activate macrophages to perform anti-tumor activities in vitro and in vivo.

In situ analysis of tumor-specific CTL effector and memory responses elicited by tumor vaccination

In this study tumor-specific CTL effector and memory responses were analyzed in normal mice, in tumor bearing mice and in animals treated by active specific immunotherapy (ASI) with an autologous virus modified tumor vaccine. In the well defined DBA/2 mouse lymphoma model ESb, the tumor specific CTL response requires interactions of four different cell types and recognition of MHC class I and class II restricted tumor antigens either on host antigen presenting cells (APCs) or on the tumor cells. The most effective in situ activation of syngeneic tumor specific CTL can be generated within no more than 9 days by primary immunization in the ear pinna and restimulation in the peritoneal cavity. Here we describe modulatory effects of either cytokines or of virus infection of tumor stimulator cells during restimulation in the peritoneal cavity on the CTL memory response. The in situ peritoneal effector cell (PEC) response was augmented when Newcastle Disease Virus (NDV) was used to infect tumor cells which expressed the correct tumor associated antigen of the memory response but not when a third party tumor cell was infected and admixed. A response could also be augmented by co-administration of interferons-alpha, -beta or IL-2 and by pre-treatment with low dose cyclophosphamide. Therapeutic vaccination effects could be achieved in mice inoculated s.c. with this aggressive and metastatic tumor variant if the vaccine was given very early, i.e. 1-2 days after priming and when the vaccine was applied post-operatively, i.e. in situations of low tumor burden. A long-term CTL memory response could be demonstrated even two months after post-operative active specific immunotherapy with ESb-NDV vaccine.

Immunological and molecular characterization of an aggressive murine lymphoma variant: modulation in vitro and in vivo

The highly metastatic murine ESb-L lymphoma was analyzed with respect to its possible origin and phenotype modulation. By determining the methylation status of the CD8 gene an early thymic origin of the ESb-L lymphoma cells is suggested. It revealed that the precursors of ESb-L cells had at least one CD8 allele expressed during their development. ESb-L tumor cells were found to express ICAM-1, ICAM-2, VLA-4 and Mel14 as adhesion molecules and homing receptors and CD25, CD69 and CD124 (HSA) as T-cell related activation markers. PCR analysis revealed that ESb-L tumor cells express a Th2-like cytokine pattern with mRNAs for IL-4, IL-5, IL-6, IL-10 and IL-13, but not for IL-2 and IFNgamma. In addition mRNA for TNFalpha, LT, IFNalpha and the chemokines MIP1alpha and MIP1beta was found. The expression of the adhesion molecules ICAM-1, ICAM-2, VLA-4 and of the T-cell activation marker CD25 on ESb-L tumor cells could be upregulated by incubating the cells with 10 ng/ml TNFalpha. For CD25 this effect was confirmed also at the mRNA level. Using the lacZ transduced T-cell lymphoma ESb-L-CI we were able to re-isolate live tumor cells from the primary site or from a metastasized liver and to investigate their phenotype ex vivo. MIP1alpha mRNA expression was strongly reduced in ex vivo isolated tumor cells as compared to in vitro grown cells indicating the modulatory role of the tumor microenvironment. The presented data suggest possible roles of TNFalpha and/or other microenvironmental factors modulating the expression of molecules involved in cell migration and adhesion thereby influencing cancer metastasis.

Sialoadhesin-positive host macrophages play an essential role in graft-versus-leukemia reactivity in mice

We recently established an effective immune T-cell-mediated graft-versus-leukemia (GVL) murine model system in which complete tumor remissions were achievable even in advanced metastasized cancer. We now describe that this T-cell-mediated therapy is dependent on host macrophages expressing the lymphocyte adhesion molecule sialoadhesin (Sn). Depletion of Kupffer cells in tumor-bearing mice during adoptive immunotherapy (ADI) or the treatment of these animals with anti-Sn monoclonal antibodies led to complete or partial inhibition of the immune T-cell-mediated therapeutic effect. Furthermore, Sn+ host macrophages in livers formed clusters during ADI with donor CD8 T cells. To test for a possible antigen presentation function of these macrophages, we used as an in vitro model the antigen beta-galactosidase for which a dominant major histocompatibility complex (MHC) class I Ld-restricted peptide epitope is known to be recognized by specific CD8 cytotoxic T lymphocytes (CTL). We demonstrate that purified Sn+ macrophages can process exogenous beta-galactosidase and stimulate MHC class I peptide-restricted CTL responses. Thus, Sn+ macrophages, which are significantly increased in the liver after ADI, may process tumor-derived proteins via the MHC class I pathway as well as via the MHC class II pathway, as shown previously, and present respective peptide epitopes to CD8 as well as to CD4 immune T cells, respectively. The synergistic interactions observed before between immune CD4 and CD8 T cells during ADI could thus occur in the observed clusters with Sn+ host macrophages.

The bacterial lacZ gene: an important tool for metastasis research and evaluation of new cancer therapies

The bacterial lacZ gene has been used to genetically tag tumor cells. This has been of value, specifically in metastasis research where it allowed to visualize micrometastases and single tumor cells in tissues. lacZ tagging has also provided the feasibility of re-isolating metastatic tumor cell populations for ex vivo molecular analyses. This review summarizes studies that have utilized lacZ tagged tumor cells to understand aspects of metastasis including dormancy, tumor-host interactions, gene modulation and anti-tumor immunity. lacZ tagging is also a valuable tool for evaluating cancer therapies.

An effective strategy of human tumor vaccine modification by coupling bispecific costimulatory molecules

A new, generally applicable procedure is described for the introduction of defined costimulatory molecules into human cancer cells to increase their T-cell stimulatory capacity. The procedure involves infection with Newcastle disease virus to mediate the cell surface binding of costimulatory molecules (e.g., specially designed bispecific antibodies (bsAb)). The modification is independent of tumor cell proliferation and laborious recombinant gene technology and can be applied directly to freshly isolated and gamma-irradiated patient-derived tumor cells as an autologous cancer vaccine. Following the infection of tumor cells with a nonvirulent strain of Newcastle disease virus, the cells are washed and then further modified by coincubation with bsAbs, which attach with one arm to the viral hemagglutinin-neuraminidase (HN) molecule on the infected tumor cells. The second specificity of one bsAb (bs HN x CD28) is directed against CD28 to augment antitumor T-cell responses by selectively channeling positive costimulatory signals via the CD28 pathway. A second bsAb (bs HN x CD3) was produced to deliver T-cell receptor-mediated signals either alone (bsCD3 vaccine) or in combination with anti-CD28 (bsCD3 vaccine plus bsCD28 vaccine). In human T-cell stimulation studies in vitro, the bsCD28 vaccine caused an up-regulation of early (CD69) and late (CD25) T-cell activation markers on CD4 and CD8 T lymphocytes from either normal healthy donors or cancer patients (autologous system) and induced tumor cytostasis in nonmodified bystander tumor cells. In addition, in combination with the bsCD3 vaccine, augmented antitumor cytotoxicity and T-cell proliferative responses were observed. This tumor vaccine modification procedure is highly specific, quick, economic, and has a broad range of clinical applications.

Nitric-oxide-induced apoptosis in human leukemic lines requires mitochondrial lipid degradation and cytochrome C release

We have previously shown that nitric oxide (NO) stimulates apoptosis in different human neoplastic lymphoid cell lines through activation of caspases not only via CD95/CD95L interaction, but also independently of such death receptors. Here we investigated mitochondria-dependent mechanisms of NO-induced apoptosis in Jurkat leukemic cells. NO donor glycerol trinitrate (at the concentration, which induces apoptotic cell death) caused (1) a significant decrease in the concentration of cardiolipin, a major mitochondrial lipid; (2) a downregulation in respiratory chain complex activities; (3) a release of the mitochondrial protein cytochrome c into the cytosol; and (4) an activation of caspase-9 and caspase-3. These changes were accompanied by an increase in the number of cells with low mitochondrial transmembrane potential and with a high level of reactive oxygen species production. Higher resistance of the CD95-resistant Jurkat subclone (APO-R) cells to NO-mediated apoptosis correlated with the absence of cytochrome c release and with less alterations in other mitochondrial parameters. An inhibitor of lipid peroxidation, trolox, significantly suppressed NO-mediated apoptosis in APO-S Jurkat cells, whereas bongkrekic acid (BA), which blocks mitochondrial permeability transition, provided only a moderate antiapoptotic effect. Transfection of Jurkat cells with bcl-2 led to a complete block of apoptosis due to the prevention of changes in mitochondrial functions. We suggest that the mitochondrial damage (in particular, cardiolipin degradation and cytochrome c release) induced by NO in human leukemia cells plays a crucial role in the subsequent activation of caspase and apoptosis.

Tumor stimulator cell modification by infection with Newcastle Disease Virus: analysis of effects and mechanism in MLTC-CML cultures

Effects of tumor stimulator cell modification by infection with Newcastle Disease Virus (NDV) are described as analysed in vitro in mixed lymphocyte tumor cell cultures (MLTC). Direct antitumor effects were seen with human melanoma or colon-carcinoma cells in a dose- and time-dependent manner when using live but not UV inactivated virus. When T cell stimulation was measured by [3H]-thymidine uptake, NDV infected tumor stimulator cells did not show an augmentation but rather an inhibitory effect in comparison to non-infected stimulator cells. Virus infected tumor stimulator cells were, however, capable of augmenting the induction of tumor specific cytotoxic T cells in MLTC-CML assays when using murine ESb lymphoma immune cells and syngeneic NDV modified ESb cells as stimulators. A CML stimulatory effect was also shown for NDV modified third party cells and thereof derived conditioned medium. These effects are most likely explained by interferon- which is induced in tumor cells by NDV infection and by interferon-á which is induced in responder cells when stimulated with NDV infected stimulator cells.

Human tumor cell modification by virus infection: an efficient and safe way to produce cancer vaccine with pleiotropic immune stimulatory properties when using Newcastle disease virus

Direct infection of tumor cells with viruses transferring protective or therapeutic genes, a frequently used procedure for production of tumor vaccines in human gene therapy, is an approach which is often limited by the number of tumor cells that can reliably be infected as well as by issues of selectivity and safety. We report an efficient, selective and safe way of infecting human tumor cells with a natural virus with interesting pleiotropic immune stimulatory properties, the avian paramyxovirus Newcastle disease virus (NDV). Two of the six viral genes (HN and F) modify the tumor cell surface by introduction of new adhesion molecules for lymphocyte interactions and other viral genes stimulate host cell genes and local production of cytokines and chemokines which can recruit a broad antitumor response in vivo. A large variety of human tumor cells is shown to be efficiently infected by NDV with viral replication being independent of tumor cell proliferation. Such properties make NDV a suitable agent for modification of noncultured freshly isolated and gamma-irradiated patient-derived tumor cells. For the apathogenic non-lytic strain NDV-Ulster which is used in our clinical vaccine trials, we demonstrate selective replication in tumor cells as compared with corresponding normal cells. Furthermore, we present evidence that new virions produced by infected tumor cells are non-infectious using three different quantitative test methods. Our results demonstrate feasibility and broad applicability of this strategy of human tumor vaccine modification. Post-operative vaccination with the autologous virus-modified vaccine ATV-NDV thus provides a reasonable potential for pleiotropic modifications of the immune response of cancer patients against their own tumor.

EblacZ tumor dormancy in bone marrow and lymph nodes: active control of proliferating tumor cells by CD8+ immune T cells

A well-defined lacZ gene tagged DBA/2 lymphoma (EblacZ) was used to examine the role of host immune responses in controlling tumor dissemination and persistence, as well as metastasis. In s.c. and intra-ear pinna-inoculated mice, low numbers of EblacZ cells homed to the bone marrow and lymph nodes. The frequency of bone marrow-residing tumor cells did not change with the growth of primary tumor or with multiple inoculations of tumor cells. The bone marrow-residing tumor cells expressed the proliferation-associated Ki67 antigen and expanded upon CD8+ depletion. In contrast, inoculation of nu/nu or severe combined immunodeficiency mice or of immune-suppressed DBA/2 mice led to the rapid outgrowth of EblacZ cells in the bone marrow and their metastasis to other organs. Transfer of bone marrow from EblacZ immunized MHC congenic or syngeneic DBA/2 donors, but not from naive donors, protected s.c.-inoculated DBA/2 mice. Protection was abrogated by in vitro depletion of CD8+ T cells prior to transfer of bone marrow. These experiments show that bone marrow and lymph nodes are privileged sites where potentially lethal tumor cells are controlled in a dormant state by the immune system. Metastasis may be a consequence of the breakdown of this immune control.

Introduction of adhesive and costimulatory immune functions into tumor cells by infection with Newcastle Disease Virus

We demonstrate in this study that infection of tumor cells by Newcastle Disease Virus (NDV) leads to changes in tumor cell surface adhesiveness and tumor immune costimulatory function. While adsorbtion of virions to the cell surface occurs after short-term (10 min) incubation and leads to cells expressing viral antigens at low antigen density (LAD), viral replication in the cytoplasm occurs within 5-24 h leading to tumor cells expressing viral antigens at high antigen density (HAD) as shown by quantitative FACS flow cytometry. Virus infected tumor cells showed an increased adhesiveness for erythrocytes and lymphocytes. When IL-2 preactivated human lymphocytes with cytotoxic potential were coincubated with 51Cr-labeled NDV-infected or non-infected human colon carcinoma cells increased lysis of the virus infected targets was observed. The virus mediated cell adhesion could be inhibited by monoclonal antibody (mAb) against the hemagglutinin-neuraminidase (HN) molecule but not by antibody against the fusion protein. HN cDNA transfectants also mediated increased lymphocyte adhesion in comparison to wild-type or neo-vector transfected control cells. Further experiments demonstrated that not only the adhesion domain of HN but also the neuraminidase plays a role in cell-cell interactions. A comparison of an NDV neuraminidase mutant of the strain Australian Victoria (AV-L1) with the parental AV strain revealed pronounced differences in their capacity to mediate lymphocyte binding and costimulatory activity. The mutant with highly decreased neuraminidase activity was very similar to NDV Ulster in adhesive and costimulatory activity while the parental line with high neuraminidase activity was negative for both functions. Costimulatory effects of NDV Ulster and AV-L1 were revealed when virions and suboptimal concentrations of anti-CD3 mAbs were coated to microtiter plates for induction of murine CD4 T cell proliferation. In human autologous mixed lymphocyte-tumor cell cultures up-regulation of T cell activation markers CD69 and CD25 was seen with NDV modified but not with non-modified tumor cells.

Graft-versus-leukemia reactivity involves cluster formation between superantigen-reactive donor T lymphocytes and host macrophages

T-cell-mediated antitumor effects play an important role clinically in allogeneic graft-versus-leukemia (GvL) reactivity, whereas T-cell-mediated antihost effects are associated with a risk of developing graft-versus-host (GvH) disease. GvL and GvH were compared in an animal tumor model system after the systemic transfer of allogeneic antitumor immune T lymphocytes from B10.D2 [H-2d; minor lymphocyte-stimulating antigen (Mls)b] mice into ESb-MP tumor-bearing or normal DBA/2 (H-2d; Mls(a)) mice. Here we demonstrate that this T-cell-mediated therapy involves the formation of clusters of donor CD4 and CD8 T cells with host macrophages, in particular, with a subpopulation expressing the lymphocyte adhesion molecule sialoadhesin. DBA/2 mice and the derived tumor ESb-MP express viral superantigen 7 (Mls(a)), an endogenous viral superantigen that is absent from B10.D2 mice. To test the contribution of viral superantigen 7-reactive Vbeta6 donor T cells in the GvL-mediated eradication of liver metastases, we performed immunohistological and transmission electron microscopy studies. Vbeta6+ CD4 and CD8 T cells from B10.D2 donors formed tight clusters with host sialoadhesin-positive macrophages, and transmission electron microscopy pictures revealed direct membrane-membrane interactions between T cells and macrophages. Clusters were more abundant and consisted of more cells in tumor-bearing hosts (GvL model) than in non-tumor-bearing hosts (GvH model). In addition, Vbeta6 T cells within the clusters showed a strong proliferation activity, indicating stimulation. Moreover, in an in vitro tumor cytostasis assay, primed as well as nonprimed purified Vbeta6 T cells from donor mice were able to inhibit the proliferation of superantigen-expressing ESb-MP lymphoma cells. This suggests that the transferred superantigen-reactive Vbeta6 T cells contribute to the eradication of metastases. The observed cell clusters might be sites for antigen presentation and the activation of tumor-reactive T cells.

Immunization with virus-modified tumor cells

Direct infection of tumor cells with viruses transfering protective or therapeutic genes-a frequently used procedure for production of tumor vaccines in human gene therapy-is often limited by the number of tumor cells that can reliably be infected, as well as by issues of selectivity and safety. In this review, we describe an efficient, selective, and safe way of infecting human tumor cells with a natural virus with interesting pleiotropic immune stimulatory properties, the avian paramyxovirus Newcastle disease virus (NDV). Advantages of this virus are its good cell-binding properties, its selective replication in tumor cell cytoplasm, which is independent of cell proliferation, and its relative safety. Most important for its use as an adjuvant in human cancer vaccine are its ability to introduce T-cell costimulatory activity, to prevent anergy induction, and to induce locally chemokines (eg, RANTES, IP-10) and cytokines (eg, interferon alpha, beta [IFN-alpha, beta] and tumor necrosis factor-alpha [TNFalpha]) that affect T-cell recruitment and activation. A further development consists of attachment-via NDV-derived hemagluttinin-neuraminidase (HN) membrane-anchoring molecules-of universal defined bispecific reagents such as T-cell-activating anti-CD28 antibodies. Finally, we summarize the status of our clinical studies with the autologous virus modified live cell vaccine (ATV)-NDV.

Antagonistic effects of systemic interleukin 2 on immune Tcell-mediated graft-versus-leukemia reactivity

This study demonstrates that systemic interleukin 2 (IL-2) can decrease the homing of syngeneic immune T cells to the target organ of metastases and accelerate unwanted side effects of allogeneic immune T cells. As a tumor system, we used the well-characterized highly aggressive DBA/2 mouse leukemia ESb and its less aggressive adhesion variant, ESb-MP. Systemic IL-2 treatment was performed with recombinant human interleukin-2 (Proleukin), which was slowly released via an implanted osmotic pump or was modified with polyethylene glycol (PEG-IL-2) to achieve constant plasma levels. Allogeneic B10.D2 antitumor immune spleen cells (ISPL cells) exerted strong graft-versus-leukemia (GvL) reactivity after adoptive transfer into late-stage ESb-MP tumor-bearing DBA/2 mice. Mls(a) superantigen-reactive vbeta6 donor T cells were not eliminated or tolerized by in vivo priming with the tumor cells and were present in active proliferation in liver infiltrates. When exogenous PEG-IL-2 or Proleukin was applied in addition to ISPL cells in such mice, the strong GvL-mediated protective immunity was converted into a fatal graft-versus-host disease. IL-2 treatment alone had no toxic effect and caused a moderate protection effect in the absence of an effect on local tumor growth. Potentiation of GvH reactivity of B10.D2 ISPL by PEG-IL-2 was proven in non-tumor-bearing DBA/2 mice, in which graft-versus-host disease was characterized by: (a) heavy hepatic lymphocytic infiltration, (b) irreversible increase of serum glutamate-oxalacetate-transaminase and glutamate-pyruvate-transaminase levels, (c) weight loss, and (d) death. Antagonistic effects of systemic IL-2 on GvL were observed with syngeneic DBA/2 anti-ESb immune peritoneal effector cells (PECs). There was a detrimental effect of systemic IL-2 on liver target organ infiltration by immune T cells causing, at day 6 after transfer, a drop from 20-30 CD4 or CD8 T cells per liver lobule in the PEC group to <5 in the PEC plus IL-2 group. The results emphasize the importance of a better understanding of IL-2 function in vivo and of its interaction with immune cell function to improve protocols for optimal application in the clinic to achieve maximal GvL effects.

Identification of four genes in endothelial cells whose expression is affected by tumor cells and host immune status--a study in ex vivo-isolated endothelial cells

A spontaneously metastasizing, well-defined mouse lymphoma was chosen as an in vivo model to study the effect of tumor-host interaction on gene expression in liver sinusoidal endothelial cells. Forty-nine bovine aortic endothelial cell (BAEC) genes, recently isolated by a differential screening approach of a cDNA library enriched for tumor necrosis factor-alpha (TNF-alpha) suppressed genes, were investigated. Four of these genes were finally selected because they were affected differentially by host immuno-competence, TNF-alpha, and tumor cells. Sequence analysis showed them to encode the bovine polyubiquitin (A4), elongation factor 1alpha (B2), the acidic ribosomal phosphoprotein PO (C3), and the ribosomal protein S2 (E10). Gene expression was analyzed by dot-blot or Northern blot analysis. TNF-alpha and tumor cell conditioned supernatant suppressed the genes additive in BAEC but not in other endothelial cells except for bovine capillary endothelial cells. Ex vivo-isolated liver endothelial cells of tumor-bearing syngeneic DBA/2 mice showed strong downregulation of these four genes in comparison to normal control values. In contrast, endothelial cells of tumor-bearing immuno-incompetent Balb/c (nu/nu) mice showed no downregulation but upregulation of these genes. Consistently, all four genes were also downregulated when BAEC were incubated with supernatants derived from ex vivo-isolated liver metastases from immuno-competent but not from -incompetent mice. Thus, the expression of a group of genes involved in protein translation and processing was more profoundly altered in endothelial cells in vivo than in vitro, suggesting that microenviromental factors and cell-cell and cell-matrix interactions play an important role.

Human T Cell Leukemia Virus-I (HTLV-I) Tax-Mediated Apoptosis in Activated T Cells Requires an Enhanced Intracellular Prooxidant State

We have shown that an estradiol-dependent activation of human T cell leukemia virus-I Tax leads to the inhibition of cell proliferation and to the induction of apoptosis. The present study demonstrates that a hormone-dependent activation of Tax promotes an enhanced prooxidant state in stably transfected Jurkat cells as measured by changes in the intracellular levels of glutathione and H2O2; these changes are followed by apoptotic cell death. Additional stimulation of the CD3/TCR pathway enhances the oxidative and apoptotic effects. Both Tax-mediated apoptosis and oxidative stress can be potently suppressed by antioxidants, as is seen with the administration of recombinant thioredoxin (adult T cell leukemia-derived factor) or pyrrolidine dithiocarbamate. Hormone-induced Tax activation induces a long-lasting activation of NF-κB, which is a major target of reactive oxygen intermediates. The long-term exposure of Jurkat cells to hormone eventually results in a selection of cell clones that have lost Tax activity. A subsequent transfection of these apparently “nonresponsive” clones allows the recovery of Tax responses in these cells. Our observations indicate that changes in the intracellular redox status may be a determining factor in Tax-mediated DNA damage, apoptosis, and selection against the long-term expression of Tax function.

Human T cell leukemia virus-I (HTLV-I) Tax-mediated apoptosis in activated T cells requires an enhanced intracellular prooxidant state

We have shown that an estradiol-dependent activation of human T cell leukemia virus-I Tax leads to the inhibition of cell proliferation and to the induction of apoptosis. The present study demonstrates that a hormone-dependent activation of Tax promotes an enhanced prooxidant state in stably transfected Jurkat cells as measured by changes in the intracellular levels of glutathione and H2O2; these changes are followed by apoptotic cell death. Additional stimulation of the CD3/TCR pathway enhances the oxidative and apoptotic effects. Both Tax-mediated apoptosis and oxidative stress can be potently suppressed by antioxidants, as is seen with the administration of recombinant thioredoxin (adult T cell leukemia-derived factor) or pyrrolidine dithiocarbamate. Hormone-induced Tax activation induces a long-lasting activation of NF-kappaB, which is a major target of reactive oxygen intermediates. The long-term exposure of Jurkat cells to hormone eventually results in a selection of cell clones that have lost Tax activity. A subsequent transfection of these apparently "nonresponsive" clones allows the recovery of Tax responses in these cells. Our observations indicate that changes in the intracellular redox status may be a determining factor in Tax-mediated DNA damage, apoptosis, and selection against the long-term expression of Tax function.

The extended packaging sequence of MoMLV contains a constitutive mRNA nuclear export function

The present report shows that incorporation of defined sequences from the Moloney murine leukaemia virus (MoMLV) into Rex dependent expression vectors based on the human T-cell leukaemia virus (HTLV-1) allows Rex independent gene expression. Deletion mutagenesis of the MoMLV derived sequences allowed this function to be localised to a 312 nt length sequence overlapping the MoMLV gag p15/p12 open reading frame. This 'extended packaging sequence' has been reported to markedly increase the titre of in vitro packaged retroviral vectors. Using fluorescent in situ hybridisation combined with confocal microscopy we show that the 312 nt element can replace Rex mediated nuclear export and expression of transcripts containing HTLV-1 cis acting repressive elements. Our observations are consistent with the extended packaging sequence of MoMLV exerting a constitutive mRNA nuclear export function.

Co-stimulatory effect of nitric oxide on endothelial NF-kappaB implies a physiological self-amplifying mechanism

Here we investigated the effects of the second messenger molecule NO at various concentrations on the activation of transcription factor NF-kappaB, IkappaB-alpha kinase (IKK-alpha), Jun N-terminal kinase (JNK) and apoptosis in murine endothelial cells. Low concentrations of NO alone failed to activate NF-kappaB, IKK-alpha and JNK. When NF-kappaB was prestimulated by TNF-alpha or phorbol 12-myristate 13-acetate, the addition of NO at low concentrations enhanced the activation of NF-kappaB. This provides a mechanism for a self-amplifying signal in the inflammatory response, since the inducible NO synthase in endothelial cells is regulated by NF-kappaB. The co-stimulatory effect of NO on NF-kappaB activation was also evident from IKK-alpha kinase assays and reporter gene experiments in endothelial cells. High doses of NO impaired the TNF-alpha-induced DNA-binding activity of NF-kappaB. Accordingly, these high amounts of NO also repressed the TNF-alpha-induced transactivation by NF-kappaB as efficient as dexamethasone. The doses of NO required for the inhibition of NF-kappaB are not cytotoxic for the endothelial cells, enabling the establishment of an autoregulatory loop for NF-kappaB signaling.

Loss of endogenous mouse mammary tumor virus superantigen increases tumor resistance

From a cross between a tumor-susceptible mouse strain (DBA/2; D) and a tumor-resistant MHC-identical strain (B10.D2; D2) new recombinant inbred mouse strains were established over many generations of inbreeding and tumor resistance selection. Since resistance to the highly metastatic DBA/2 lymphoma variant ESb had an immunologic basis, and the two parental strains differed in endogenous viral superantigens (vSAGs), DNA of three D2 x D recombinant inbred mouse lines was typed for endogenous mouse mammary tumor viruses using mouse mammary tumor virus long terminal repeat- and env gene-specific probes. The resistant D2 x D mice were very similar to the susceptible parental strain D in their Mtv Southern blots, except for the lack of a single band corresponding to Mtv-7, the provirus coding for the strong DBA/2 superantigen Mls-1a. A backcross analysis revealed that Mtv-7-negative F2 mice were significantly more resistant than Mtv-7-positive F2 mice. When Mtv-7 was reintroduced into the resistant lines by crossing them with either CBA/J or BALB/D2.Mls-1a, the mice became again more tumor susceptible. Finally, we demonstrate the ability to transfer immunoresistance and graft-vs-leukemia reactivity from tumor-resistant to tumor-susceptible mice.

Loss of Endogenous Mouse Mammary Tumor Virus Superantigen Increases Tumor Resistance

From a cross between a tumor-susceptible mouse strain (DBA/2; D) and a tumor-resistant MHC-identical strain (B10.D2; D2) new recombinant inbred mouse strains were established over many generations of inbreeding and tumor resistance selection. Since resistance to the highly metastatic DBA/2 lymphoma variant ESb had an immunologic basis, and the two parental strains differed in endogenous viral superantigens (vSAGs), DNA of three D2×D recombinant inbred mouse lines was typed for endogenous mouse mammary tumor viruses using mouse mammary tumor virus long terminal repeat- and env gene-specific probes. The resistant D2×D mice were very similar to the susceptible parental strain D in their Mtv Southern blots, except for the lack of a single band corresponding to Mtv-7, the provirus coding for the strong DBA/2 superantigen Mls-1a. A backcross analysis revealed that Mtv-7-negative F2 mice were significantly more resistant than Mtv-7-positive F2 mice. When Mtv-7 was reintroduced into the resistant lines by crossing them with either CBA/J or BALB/D2.Mls-1a, the mice became again more tumor susceptible. Finally, we demonstrate the ability to transfer immunoresistance and graft-vs-leukemia reactivity from tumor-resistant to tumor-susceptible mice.

Nucleocytoplasmic transport of HTLV-1 RNA is regulated by two independent LTR encoded nuclear retention elements

Appropriate expression of HTLV-1 genes requires transcriptional transactivation by Tax and post-transcriptional regulation by Rex, both mediated by LTR encoded RNA sequences. Using a combination of deletion mutagenesis, Rex-reporter CAT assays, fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy it was established that in the absence of Rex, CAT mRNAs harboring HTLV-1 LTR sequences were unable to leave the nucleus. Deletion of the known U5 encoded cis-acting repressing sequence (CRS) led to a partial release of nuclear retention. A novel regulatory element overlapping the 3' Rex responsive element (RxRE) region was shown to prevent export and expression of these transcripts. Deletion of both the 5' LTR encoded CRS and 3' LTR encoded downstream repressive sequence (3' CRS) led to constitutive mRNA nuclear export and gene expression, independently of Rex. The locations of the two regulatory elements indicate that while the 5' CRS selectively acts to hinder export of unspliced transcripts, the 3' CRS has the capacity to induce nuclear retention of all HTLV-1 transcripts, and therefore could potentially contribute to viral latency in infected cells.

Superiority of the ear pinna over muscle tissue as site for DNA vaccination

Three different vaccination sites were compared for efficiency of immunization with naked DNA. Using the bacterial lacZ gene as a model, all three sites of the mouse (skeletal muscle, dermis of abdominal skin or of the ear pinna) could express the gene product beta-gal but varied in expression time with muscle tissue showing the longest expression. Expression time, however, did not correlate with immune response intensity. The ear pinna was by far the most effective and muscle the least effective priming site for specific humoral and cytotoxic T cell-mediated immune responses. Following intra-pinna DNA inoculation, beta-gal expressing cells were detectable around the injection site and in the major draining lymph node. Efficiency of immunization was also dependent on the promoter and expression vector used. The cytomegalus virus promoter driven pCMV beta vector was superior to the Moloney murine leukemia virus LTR driven BAG vector. LacZ DNA immunization was also compared with cell-based vaccination with lacZ-transfected tumor cells, in which case again the pinna was the best site for inducing strong immune responses. Tumor-specific T cell responses could also be well induced in the pinna, leading to cytotoxic T lymphocyte induction and protective antitumor immunity. Thus, the pinna was found to be a privileged site for induction of antitumor responses and for genetic immunization, an important finding of immediate practical and potential future clinical implications.

Caspase activation is required for nitric oxide-mediated, CD95(APO-1/Fas)-dependent and independent apoptosis in human neoplastic lymphoid cells

Nitric oxide (NO), an important effector molecule involved in immune regulation and host defense, was shown to induce apoptosis in lymphoma cells. In the present report the NO donor glycerol trinitrate was found to induce apoptosis in Jurkat cells that are sensitive to CD95-mediated kill. In contrast, a CD95-resistant Jurkat subclone showed substantial protection from apoptosis after exposure to NO. NO induced mRNA expression of CD95 (APO-1/Fas) and TRAIL/APO-2 ligands. Moreover, NO triggered apoptosis in freshly isolated human leukemic lymphocytes which were also sensitive to anti-CD95 treatment. The ability of NO to induce apoptosis was completely blocked by a broad-spectrum ICE (interleukin-1beta converting enzyme)-protease/caspase inhibitor and correlated with FLICE/caspase-8 activation. This activation was abrogated in some neoplastic lymphoid cells but not in others by the inhibitor of protein synthesis cycloheximide. Our results were confirmed using an in vitro experimental model of coculture of human lymphoid target cells with activated bovine endothelial cells generating NO as effectors. Furthermore, the inhibition of endogenous NO production with the inducible NO synthase inhibitor NG-monomethyl-L-arginine caused a complete abrogation of the apoptotic effect. Our data provide evidence that NO-induced apoptosis in human neoplastic lymphoid cells strictly requires activation of caspases, in particular FLICE, the most CD95 receptor-proximal caspase. Depending on the cell line tested this activation required or was independent of the CD95 receptor/ligand system.

Purification and identification of chemokines potentially involved in kidney-specific metastasis by a murine lymphoma variant: induction of migration and NFkappaB activation

The ESb-MP cell line is the subclone of a highly malignant variant of murine methylcholanthrene-induced T lymphoma, ESb. When injected in vivo, ESb-MP cells metastasize to the kidney with high frequency, whereas a non-adherent variant, ESb cells, rarely form metastatic foci in the kidney. Our previous results showed that ESb-MP, but not ESb, cells were able to migrate in response to murine kidney-conditioned media (KCM). In an effort to characterize the tumor cell chemoattractant(s) produced by kidney cells, we found that the murine kidney mesangial cell line MES-13 released more chemotactic activity for ESb-MP cells than present in KCM. A major heparin-binding chemotactic activity was purified to homogeneity by sequential fast-performance liquid chromatography and reversed phase high-performance liquid chromatography. Amino acid sequencing of the formic acid-digested active fractions revealed that the purified protein was identical to murine MCP-1(JE) and its activity was neutralized by an anti-MCP-1(JE) antibody. Another chemokine, RANTES, was also purified from MES-13 cell supernatant. The chemotactic activity contained in the MES-13 cell supernatant and in murine KCM was neutralized in part by a combination of anti-MCP-1(JE) and anti-RANTES antibodies. We further examined the differences in the ESb-MP and ESb cells. Binding studies using a variety of radio-iodinated chemokines showed that although both ESb-MP and ESb cells expressed substantial levels of high-affinity binding sites for CC chemokines, only ESb-MP cells migrated in response to CC chemokines and these cells constitutively expressed higher levels of beta2 integrin adhesion protein CD11b than their parental ESb cells. CC chemokines also activated NFkappaB in ESb-MP but not in ESb cells. Our results indicate that CC chemokines selectively chemoattract and activate ESb-MP cells. Thus, locally produced chemokines, MCP-1(JE) and RANTES in particular, may contribute to the preferential metastasis of ESb-MP cells to the kidneys.

Sulfated glycosaminoglycans enhance tumor cell invasion in vitro by stimulating plasminogen activation

Metastasizing tumor cells invade host tissues by degrading extracellular matrix constituents. We report here that the highly sulfated glycosaminoglycans, heparin and heparan sulfate, as well as the sulfated polysaccharide, fucoidan, significantly enhanced tumor cell invasion in vitro into fibrin, the basement membrane extract, Matrigel, or through a basement membrane-like extracellular matrix. The enhancement of tumor cell invasion was due to a stimulation of the proteolytic cascade of plasminogen activation since the effect required plasminogen activation and was abolished by inhibitors of urokinase-type plasminogen activator (uPA) or plasmin. Sulfated polysaccharides enhanced five reactions of tumor-cell initiated plasminogen activation in a dose-dependent manner. They amplified plasminogen activation in culture supernatants up to 70-fold by stimulating (i) pro-uPA activation by plasmin and (ii) plasminogen activation by uPA. (iii) In addition, sulfated polysaccharides partially protected plasmin from inactivation by alpha 2-antiplasmin. Sulfated polysaccharides also stimulated tumor-cell associated plasminogen activation, e.g., (iv) cell surface pro-uPA activation by plasmin and (v) plasminogen activation by cell surface uPA. These results suggest that sulfated glycosaminoglycans liberated by tumor-cell mediated extracellular matrix degradation in vivo might amplify pericellular plasminogen activation and locally enhance tumor cell invasion in a positive feedback manner.

Bispecific antibodies increase T-cell stimulatory capacity in vitro of human autologous virus-modified tumor vaccine

The production and functional testing of two new bispecific (bs) hybrid antibodies [Abs; bs Ab hemagglutinin-neuraminidase (HN) x CD3 and bs Ab HN x CD28] designed for cancer vaccine modification are described. They allow distinct modifications of the human tumor cell vaccine ATV-NDV, an autologous tumor cell vaccine already modified by infection with Newcastle disease virus. The bs Abs use the viral HN molecule as a common foreign anchoring molecule for attachment to the tumor cells and allow the introduction of anti-CD3 or anti-CD28 T-cell-stimulatory molecules. The bs Abs attached to tumor target cells were able to cross-link CTL effector cells and up-regulate T-cell activation markers on autologous cancer patient-derived CD4 and CD8 T lymphocytes. This strategy of combining a cellular vaccine with a bs Ab is highly specific, quick, and economical and has broad-range applications. Five ng or less of target cell-bound bs Ab HN x CD28 were effective at augmenting T-cell-mediated antitumor cytotoxicity.

Superiority of the ear pinna over a subcutaneous tumour inoculation site for induction of a Th1-type cytokine response

This study examines whether a correlation may be found between Th1- or Th2-type cytokine responses and resistance or susceptibility to tumour growth. Cytokine profiles were investigated in a well-defined mouse tumour model in which the injection site and the genetic background determine the phenotype of either tumour resistance or tumour susceptibility. DBA/2-derived ESb lymphoma variant cells with high metastatic capacity were inoculated into syngeneic mice either s.c., where they grow and metastasize, or into the ear pinna (i.e.), where they do not grow because of induction of protective immunity. Alternatively, the tumour cells were injected s.c. or i.e. into allogeneic B10.D2 mice, which are resistant to the tumour although they are identical at the MHC locus. Between 1 and 10 days after tumour cell injection the spleen-derived mRNA was tested for cytokine gene expression or the spleen cells were analysed by FACScan for T cell activation. The strongest cytokine response was observed in i.e. inoculated B10.D2 mice. This was characterized by an early (days 2-3) peak of interferon gamma (INF-gamma), interleukin-2 (IL-2), IL-2 receptor alpha (IL-2Ralpha) and IL-4. The cytokine mRNA response of i.e. inoculated DBA/2 mice was quite similar except that no IFN-gamma could be detected. In s.c. inoculated B10.D2 mice, the IL-2, IL-2Ralpha and IFN-gamma responses were weaker than after i.e. injection while the IL-4 response was comparable. The most striking difference between these cytokine profiles from tumour-resistant mice and those of s.c. inoculated tumour-susceptible DBA/ 2 mice was a delay in the latter in the IL-2, IL-2Ralpha and IFN-gamma responses and the observation that the IL-4 response was not down-regulated. The persisting IL-4 response could down-regulate a Th1-type response and thereby explain tumour susceptibility as a consequence of host conditioning.

Prospects for cytokine and chemokine biotherapy

Cytokines with immunostimulating effects have the capacity to induce tumor immunity in animal models, whereas some cytokines interfere with tumor growth based on their angiostatic effects. Despite these capabilities, cytokines, such as IFN-, IFN-, tumor necrosis factor, interleukin (IL)-1, and IL-2, have had limited clinical efficacy and many undesirable side effects. In preclinical models, cytokines can even promote tumor growth and increase metastatic spread. Although chemokines have had limited clinical evaluation, studies of animal models show that they can also have tumor-suppressive or tumor-enhancing effects. In mice, chemokines, such as IP-10, RANTES, and TCA3, have resulted in tumor regression and immunity to subsequent tumor challenge. Those chemokines that are angiostatic (e.g., PF4, IP-10, and MIG) can also induce tumor regression by reducing the tumor blood supply. Conversely, IL-8, which is angiogenic, can promote tumor growth. Our studies show that nasopharyngeal cell line cells (FADU) show a chemotactic as well as a proliferative response to MCP-1. In addition, a variant murine T cell lymphoma cell line Esb-MP, unlike the parental variant Esb, was selectively chemoattracted by murine MCP-1/JE. When injected s.c. into mice, the Esb-MP variant metastasized to the kidney with much higher frequency than the Esb variant. Both cultured kidneys from normal mice and a mesangial cell line constitutively produced chemoattractants that acted on Esb-MP but not Esb parental cells. Purification to homogeneity of these chemoattractants led to the identification of RANTES and JE. These results demonstrate that some chemokines may promote tumor growth and organ-specific metastatic spread of those tumors that have adapted and become responsive to chemokines. Finally, tumors appear to use numerous adaptive mechanisms to subvert and suppress the immune system. More effective therapy with cytokines and chemokines will require better characterization of the means by which tumors develop resistance to cytokines and overcome the immune system. Only then can we develop appropriate therapeutic approaches to antagonize cancer-induced immunosuppression.

Effective introduction of T cell costimulatory molecules into virus modified tumor cell vaccines by modification with bispecific antibodies

This report describes the generation of bispecific antibodies which bind with one arm to virus modified tumor cell vaccines and introduce with the other arm anti-murine CD28 T cell costimulatory molecules. This is an effective alternative to somatic gene therapy strategies using genes coding for ligands of CD28 such as CD80 (B7-1) or CD86 (B7-2). While these B7 molecules interact not only with CD28 but also with CLTA-4, thereby generating a negative signal, agonistic anti CD28 antibodies only bind to CD28 and therefore deliver only positive costimulatory signals. The new bispecific antibody (bsAb) HN x CD28 allows the introduction of anti-CD28 antibodies into the tumor cell vaccine ATV-NDV, an autologous tumor cell vaccine already modified by infection with Newcastle Disease Virus (NDV). The bsAb HN x CD28 attaches with its anti-HN binding site to the NDV derived hemagglutinin-neuraminidase (HN) molecule which serves as a common foreign anchoring molecule in the vaccine. NDV infected tumor cells which were further modified with HN x CD28 on their cell surface (bs-vaccine), showed increased T cell stimulatory capacity in vitro. This was revealed by augmented proliferation as well as augmented CTL activity. When syngeneic mice were injected with aggressive murine ESb lymphoma cells which were infected with NDV and further modified with the bsAb HN x CD28, delayed tumor development and prolonged survival was observed in comparison to respective controls.

In vivo 1H-NMR microimaging with respiratory triggering for monitoring adoptive immunotherapy of metastatic mouse lymphoma

The metastatic ESb-MP murine lymphoma in DBA/2 mice has been used as a model for investigating metastatic disease and its cure by adoptive immunotherapy (ADI) as monitored by in vivo multislice spin-echo 1H NMR microimaging at 7 T. isoflurane inhalation anesthesia facilitated long measurement sessions, and respiratory gating with a fiber-optic sensor greatly reduced motional artifacts. With T2 weighting (TR = 2 s, TE = 30 ms) mean signal-to-noise ratios of 30 and 15 for kidney and liver, respectively, were achieved in 20 min (100-micron pixels, 1-mm slices, 25-mm field of view). Without the use of contrast agents, metastases with diameters > or = 0.3 mm in the imaged plane could be detected as hyperintense lesions in kidney (contrast ratio ca. 1.4) and liver (contrast ratio ca. 2) with a confidence level of > 98%. For the first time the complete eradication of late-stage macroscopic metastases by ADI could be demonstrated noninvasively by MRI.

The mouse filensin gene: structure and evolutionary relation to other intermediate filament genes

Filensin and phakinin are two lens-specific members of the intermediate filament (IF) superfamily of proteins. They coassemble to form a beaded submembraneous filamentous network, the beaded filaments (BFs). The low sequence homology and differences in assembly compared to other IF proteins do not allow their classification in any of the five IF subgroups. The organization of the phakinin gene exon/intron boundaries provides evidence that this partner may be sharing a common origin with type I cytokeratin genes. Here we report the molecular cloning, sequence and characterization of the mouse filensin gene. The filensin gene consists of 8 exons and 7 introns, with 6 introns interrupting its rod domain in a highly conserved manner characteristic of type III IF genes, like vimentin, desmin, or peripherin. Of the two tail domain exons the one adjacent to the rod domain, compares to exon 7 of the non-neuronal cytoplasmic IF gene of helix aspersa and to the lamin region bridging the end of the rod domain to the nuclear localization signal. Altogether, these observations indicate that the lens beaded filaments form an independent class of IF.

Virus potentiation of tumor vaccine T-cell stimulatory capacity requires cell surface binding but not infection

This study elucidates a basically new mechanism of function of a virus-modified tumor cell vaccine which has been successful in mouse tumor models (metastatic ESb lymphoma and B16-F10 melanoma) in preventing or delaying metastatic spread and improving survival and which is being tested in clinical studies. Modification of tumor cells by a low dose of Newcastle disease virus (NDV), which caused this therapy effect, led to an augmentation of the tumor-specific cytotoxic CD8 T-cell (CTL) response and to increased CD4 T-helper activity in the absence of an antiviral T-cell response. When various noninfectious NDV preparations, which, according to newly established quantitative tests, had lost one or several of the viral functions, were tested, noninfectious virus particles with inactive fusion proteins and virus inactivated by UV light, which could fuse but could not replicate, were as active as infectious NDV in the tumor-specific CTL response. In contrast, NDV inactivated by heat treatment (NDV-HI) had no effect on the CTL response. NDV-HI, even when added to the cultures in excess, did not modulate the antitumor CTL response, which argues against a nonspecific adjuvant effect. There was no mitogenic effect of NDV. Because NDV-HI was not able to bind to the tumor cell surface and because hemagglutinin-neuraminidase c-DNA transfectants increased antigen-presenting function as virus-modified cells do, we propose that the NDV effect in the CTL response is caused by the introduction of functional viral hemagglutinin-neuraminidase molecules (1000 per virus particle) into the tumor cell surface, thereby facilitating cell-cell interactions through their cell-binding and neuraminidase activity.