Butyric acid enhances in vivo expression of hTNF-alpha in transduced melanoma cell line

Butyric acid (NaBut) and its derivatives are well-known agents eliciting tumor cell differentiation and apoptosis. In experimental models, NaBut is also used to enhance the efficacy of viral vectors. With the use of B78 murine melanoma cells transduced with the retroviral vector containing human tumor necrosis factor alpha (hTNF-alpha) gene, we investigated the ability of NaBut to increase the cytokine expression. We observed an increase in hTNF-alpha expression in vitro after incubation with NaBut. We also describe that the NaBut pro-drug tributyrin is able to increase hTNF-alpha expression in transduced B78 cells in a tumor vaccination model in mice. This observation strongly suggests a novel potential role for NaBut and its derivatives in tumor therapy. It could be used not only as a therapeutic directly acting on tumor cells but, in parallel, as a genetic vaccine "enhancer".

IL-12 suppression during experimental endotoxin tolerance: dendritic cell loss and macrophage hyporesponsiveness

Endotoxin tolerance, the transient, secondary down-regulation of a subset of endotoxin-driven responses after exposure to bacterial products, is thought to be an adaptive response providing protection from pathological hyperactivation of the innate immune system during bacterial infection. However, although protecting from the development of sepsis, endotoxin tolerance also can lead to fatal blunting of immunological responses to subsequent infections in survivors of septic shock. Despite considerable experimental effort aimed at characterizing the molecular mechanisms responsible for a variety of endotoxin tolerance-related phenomena, no consensus has been achieved yet. IL-12 is a macrophage- and dendritic cell (DC)-derived cytokine that plays a key role in pathological responses to endotoxin as well as in the induction of protective responses to pathogens. It recently has been shown that IL-12 production is suppressed in endotoxin tolerance, providing a likely partial mechanism for the increased risk of secondary infections in sepsis survivors. We examined the development of IL-12 suppression during endotoxin tolerance in mice. Decreased IL-12 production in vivo is clearly multifactorial, involving both loss of CD11c(high) DCs as well as alterations in the responsiveness of macrophages and remaining splenic DCs. We find no demonstrable mechanistic role for B or T lymphocytes, the soluble mediators IL-10, TNF-alpha, IFN-alphabeta, or nitric oxide, or the NF-kappaB family members p50, p52, or RelB.

Potentiatied antitumor effectiveness of combined chemo-immunotherapy with interleukin-12 and 5-fluorouracil of L1210 leukemia in vivo

In this study we investigated the efficacy of a combination of IL-12 and 5-FU, a chemotherapeutic exerting several immunomodulatory effects, in murine L1210 leukemia. Mice inoculated with 1 x 10(5) leukemia cells were treated with a single dose of 5-FU (50 mg/kg) and seven daily doses of IL-12 (100 ng/dose), and were observed for survival. Treatment with IL-12 or 5-FU given alone produced moderate anti-leukemic effects. However, combination of both drugs resulted in a significant prolongation of mouse survival time. Importantly, there were 70% of long-term (>60 days) survivors among mice treated with both agents simultaneously. Moreover, we observed 100% of long-term survivors when mice were treated with a minimally increased dose of IL-12 (170 ng) in combination with 5-FU (50 mg/kg). The antileukemic effects were completely abrogated in scid/scid mice and in mice depleted of peritoneal macrophages and significantly decreased after administration of anti-CD3+, anti-CD4+ or anti-CD8+ monoclonal antibodies. Administration of anti-NK1.1 antibodies did not decrease the antileukemic effects indicating that NK cells are not important effectors of this treatment regimen. Collectively, these results indicate that the combination of IL-12 and 5-FU is inducing strong antileukemic responses that are dependent on the presence and activity of macrophages and T lymphocytes and warrant further studies of combined chemo-immunotherapy with IL-12.

BRCA2 germline mutations in male breast cancer patients in the Polish population

Breast cancer is a rare disease in men. Germ-line mutations in BRCA2 and androgen receptor (AR) genes are thought to be responsible for a proportion of male breast cancer cases. The present study was performed on a series of 37 consenting patients not selected for family history of breast/ovarian cancer. The entire coding region of the BRCA2 gene and two exons of the AR gene were analyzed for germ-line mutations to evaluate the association between BRCA2 and AR genes and male breast cancer in Poland. We identified four frameshift mutations (11%) in exons 10, 11, 17 and 18, two of them were novel: 6495del3insC and 8457insA. Three missense unclassified variants (8%) of the BRCA2 gene were also identified. The frequencies of missense alterations were examined in a set of 200 chromosomes. No alteration of the AR gene was found. We did not observe much difference in clinicopathological features between carriers and non-carriers of BRCA2 mutations. Five of 37 patients (14%) had a family history of breast cancer, in one first- or second-degree relative, among the latter was one mutation carrier. The results of this study suggest that germ-line BRCA2 mutations account for rather small proportion of male breast cancer in Poland.

Genetically modified tumour vaccines: an obstacle race to break host tolerance to cancer

The development of genetically modified tumour vaccines (GMTV) has been prompted by a better understanding of antitumour immune responses and genetic engineering technologies, as well as the identification of numerous tumour antigens (TA) in several malignancies which occasionally induce spontaneous tumour regressions. Cellular vaccines are based on autologous or allogeneic tumour cells genetically engineered to secrete different cytokines, co-stimulatory molecules, or allogeneic HLA molecules in order to provide a strong stimulatory signal together with the presented TA. Another promising approach that is targeted towards breaking immune tolerance to TA, exploits dendritic cells (DC) loaded or genetically modified with TA (and sometimes cytokines). Effective nonviral and viral gene delivery systems have been constructed including a third generation of adenoviral, lentiviral and hybrid vectors. Studies in mice demonstrated that therapeutic, curative immune responses might be elicited by GMTV. Promising results from animal studies are rarely seen in human trials. Several reasons, such as numerous escape mechanisms of slowly evolving spontaneous tumours and immune incompetence of advanced patients, are major concerns. Improved monitoring of immune responses to GMTV is essential to distinguish between responders and non-responders in order to tailor immune therapy strategy to the individual patient.

The designer cytokine hyper-IL-6 mediates growth inhibition and GM-CSF-dependent rejection of B16 melanoma cells

The low immunogenic B16 melanoma cell line was transfected with a mammalian expression vector containing the complementary DNA for a sIL-6R/IL-6 fusion protein, termed Hyper-IL-6 (H-IL-6), which was shown to have biological activities at 100-1000-fold lower concentrations than IL-6 in combination with sIL-6R. The secreted p84 glycoprotein was detected in the supernatant of transfected cells and was fully active on BAF3/gp130 cells, which respond to IL-6/sIL-6R but not to IL-6 alone. Administration of recombinant H-IL-6 to C57BL/6 mice resulted in a prolonged acute phase protein gene expression indicating long systemic persistence of the fusion protein. Transfected B16 cells (B16/H-IL6 cells) showed morphological alterations in combination with a dramatic growth inhibition in vitro. Subcutaneous injection in C57BL/6 mice resulted in an almost complete rejection of B16/H-IL6 cells. This effect was partially abolished in FVB/BL/6 mice transgenic for a GM-CSF receptor antagonist, indicating a GM-CSF-dependent rejection of H-IL-6 transfected B16 cells. These results demonstrate that the anti-tumor effect of cytokines like IL-6 which are secreted by transfected melanoma cells at least in part depends on GM-CSF activity.

The 14th European Immunology Meeting--EFIS 2000. 23-27 September 2000, Poznañ, Poland

The 14th European Immunology Meeting--EFIS 2000, held in Poznan, Poland on 23-27 September 2000, was the last major meeting of European immunologists in the second millennium. This conference was intended to summarise past achievements and to present future prospects in immunology. The philosophy of the scientific program was to fuse fundamental and clinical immunology and give a chance for basic scientists and clinicians to discuss mutual topics in a general view. There were eight state-of-art lectures, 12 'meet an expert' sessions, 20 plenary sessions and 46 workshops. More than 900 works were presented. Significant interest was focused on several aspects of cancer immunology and immunotherapy. EFIS 2000 was accompanied by six pre-congress satellite symposia held in various Polish cities. The topics were, 'Heat shock proteins: immune, stress response and apoptosis' (Gdansk), 'Infectious immunity and vaccines' (Kazimierz Dolny), 'Mononuclear phagocytes in basic and clinical immunology' (Cracow), 'Immunology of reproduction' (Poznan), 'Primary immunodeficiencies' (Warsaw) and 'Glycoimmunology' (Wroclaw).

Antitumor effects of the combination therapy with TNF-alpha gene-modified tumor cells and interleukin 12 in a melanoma model in mice

In the present study, TNF-alpha gene-transduced B78 melanoma cells (B78/TNF) were used as a vaccine and combined with interleukin (IL)-12 in the treatment of B78 melanoma-bearing mice. The combined administration of genetically modified melanoma cells and IL-12 induced specific protective antitumor immunity resulting in a decreased rate of the tumor take following a rechallenge with parental B78 cells. When used therapeutically, intratumoral injections of irradiated B78/TNF melanoma cells and IL-12 exerted strong antitumor effects and led to complete regression of established tumors in 50% of mice. Injections of irradiated B78/TNF cells alone did not influence tumor development and IL-12 itself significantly delayed tumor growth but without curative effect. FACS analysis of parental B78 melanoma cells and its B78/TNF genetically modified variant showed that a proportion of cells of both cell lines expressed 87-1 (CD80) costimulatory molecule and that the expression of this molecule was increased during incubation with IFN-gamma. Moreover, IFN-gamma markedly augmented expression of major histocompatibility class (MHC) class I and II molecules on B78/TNF cells that were primarily MHC class I and II negative with no substantial effect on MHC-negative parental B78 melanoma. IFN-gamma also synergized in cytostatic/cytotoxic effects with TNF-alpha against B78 melanoma in vitro. Lymphocyte depletion studies in vivo showed reduction of the antitumor response in mice treated with anti - NK monoclonal antibodies (mAbs) as well as in mice treated with anti-CD4+ anti-CD8 mAbs. The results suggest that, when used therapeutically, IL-12 and a vaccine containing TNF-alpha gene-transduced tumor cells may reciprocally augment their overall antitumor effectiveness by facilitating development of systemic antitumor immunity and by stimulating local effector mechanisms of the tumor destruction.

Genetically modified tumour vaccines (GMTV) in melanoma clinical trials

Since melanoma is a model immunogenic malignancy incurable in the disseminated phase of its natural course different immunotherapeutic approaches are tested in clinical trials. A number of tumour vaccines genetically modified (GMTV), with various immunostimulatory factors, are tested in phase I/II clinical trials. These factors include cytokines, tumour antigens (TA), costimulatory molecules or HLA antigens. We have designed a novel, mixed auto/allogeneic cellular melanoma vaccine modified with the IL-6 and the sIL-6R genes. Preclinical studies in a mouse model demonstrated that the IL-6/sIL-6R based vaccine is able to elicit efficient anti-tumour responses, mediated by CD8+ and NK cells, which resulted in inhibition of the tumour growth, metastases formation and prolonged survival of the animals treated. Irradiation of vaccine cells does not only lead to their sterilisation but also causes increased secretion of exogenous IL-6 and sIL-6R. Since January 1996 we have vaccinated more than one hundred metastatic melanoma patients. Promising clinical results (22% CR+PR, 32% SD) and the evidence of immune responses in the vaccinated patients have prompted us to design a phase III clinical trial which is to be open in 2000.

Expression of interleukin-6, interleukin-6 receptor, and glycoprotein 130 correlates with good prognoses for patients with breast carcinoma

BACKGROUND

Interleukin-6 (IL-6) is secreted by normal epithelial breast cells but not by oncogene-transformed cells. Interleukin-6 is able to inhibit growth of breast carcinoma cells in culture. Interleukin-6 exerts its activity via two receptor subunits, IL-6R and glycoprotein 130 (gp130). The expression of these receptor subunits in breast tumors has been studied, but there are no previous reports of their prognostic significance, to the authors' knowledge.

METHODS

mRNA of IL-6, IL-6R, and gp130 was studied in 75 tumor samples obtained from breast carcinoma patients. Patients were followed for a maximum of 71 months (median follow-up, 61 months; 60 patients were followed for a minimum of 5 years or died during the observation period). Prognostic factors were analyzed in univariate and multivariate analysis.

RESULTS

mRNA specific to IL-6, IL-6R, and gp130 was detected in 57%, 53%, and 71% of breast carcinoma tissues, respectively. Expression was strongly correlated with earlier stages of the disease. In univariate analysis, expression of IL-6 and its receptor subunits proved to be a positive prognostic factor for overall survival (OS) and disease free survival (DFS). IL-6R and gp130 expression were good independent prognostic factors for OS. The 5-year OS of all patients was 66%. The 5-year OS in IL-6, IL-6R, and gp130 positive groups was 95%, 94%, and 90%, respectively, whereas in negative groups it was 26%, 31%, and 9%, respectively.

CONCLUSIONS

Expression of IL-6, IL-6R, and gp130 in breast carcinoma tissue is associated with earlier stages of the disease. In advanced stages, expression of IL-6 and its receptor subunits predicts better prognosis.

Interleukin-6 and oncostatin M-induced growth inhibition of human A375 melanoma cells is STAT-dependent and involves upregulation of the cyclin-dependent kinase inhibitor p27/Kip1

Interleukin-6 (IL-6)-type cytokines lead to growth arrest of human A375 melanoma cells. The present study demonstrates that this effect depends on the activation of STAT transcription factors. We observed a correlation between the extent of growth inhibition exerted by IL-6, IL-6 plus soluble IL-6 receptor or oncostatin M (OSM) and the intensities of STAT3 and STAT1 signals. A truncated chimeric receptor retaining only the membrane-proximal region of gp130, the common signal transducer of IL-6-type cytokines, did neither activate STATs nor mediate growth arrest of stable transfectants. These functions were restored by the addition of short STAT recruitment modules comprising critical tyrosine residues from gp130 (Y767, Y814). A receptor carrying tyrosine module Y759 of gp130 effectively mediated activation of the phosphatase SHP-2 but did not alter cell growth. Overexpression of dominant negative forms of STAT3 but not STAT1 abrogated the inhibitory effect of OSM and IL-6 in A375 cells. In addition, we have identified the cyclin-dependent kinase inhibitor p27/Kipl as a novel target to be regulated by IL-6-type cytokines. Stimulation-dependent upregulation of p27 mRNA occurred STAT3-dependently. Also p27 protein accumulated which coincided with the disappearance of hyperphosphorylated retinoblastoma protein in three human melanoma cell lines sensitive to IL-6-type cytokines.

Genetically modified tumour vaccines--where we are today

Tumour vaccines are based on weakly immunogenic specific tumour antigens admixed with adjutants in order to elicit, restore or augment antitumour immune responses against residual or metastatic tumour cells. Cellular cytotoxicity is considered to play a major role in eliminating tumour cells. Activation of cellular toxicity requires at least three synergistic signals: presentation of specific tumour antigen, constimulatory signal (B7 molecules) and propagation signal (cytokines). Recently several HLA-restricted specific tumour antigens recognized by cytotoxic T-cells have been characterized. Antibody defined antigens, heat shock proteins and viral antigens are also discussed. First generation vaccines made of whole cancer cells or tumour-cell lysates together with non-specific adjutants produced about 20% of clinical responses and are currently tested in prospective clinical trials. Novel second generation of tumour vaccines employ genetically modified tumour cells, antigen presenting cells (dendritic cells) or recombinant tumour antigens. Tumour cells are modified with genes encoding molecules providing signals for cytotoxic T-cells required for recognition and killing of cancer cells such as B7 constimulatory molecules, HLA proteins and genes of different cytokines. Dendritic cells are modified with genes of specific tumour antigens in order to activate both helper and cytotoxic T-cells. Novel vaccines produce specific immune responses and objective clinical responses with minimal toxicity in phase I/II trials. Advances in gene transfer technology, tumour immunology and better methods of monitoring specific antitumour immune responses allow the hope that tumour vaccines will be introduced into the clinic, at least in some malignancies resistant to systemic therapy so far such as melanoma and renal cell carcinoma.

Severe rheumatoid arthritis prohibits the pregnancy-induced decrease in alpha3-fucosylation of alpha1-acid glycoprotein

Patients suffering from rheumatoid arthritis (RA) may experience a temporary reduction of disease symptoms during pregnancy. As indicated by the occurrence of RA-disease symptoms during pregnancy, three categories of patients were defined, namely, remission, relapse and unchanged. In all three categories changes in the plasma level and glycosylation of alpha1-acid glycoprotein (AGP) were determined longitudinally in comparison to those occurring in pregnancy of healthy women. In healthy pregnancy, we observed: (i) a peak in the plasma concentration at week 18 and a minimum at week 30; (ii) a continuous increase in the degree of branching of the glycans during the entire pregnancy period, and (iii) a decrease in the degree of alpha3-fucosylation of AGP-glycans with a minimum occurring at week 25. Comparable pregnancy-induced changes in glycosylation were found for two other acute-phase proteins alpha1-protease inhibitor (PI) and alpha1-antichymotrypsin (ACT). Increased oestrogen levels, known to occur during pregnancy, may be one of the factors that induce these changes, because the increased branching and decreased alpha3-fucosylation is in agreement with our earlier findings regarding an involvement of this hormone in the regulation of acute phase protein glycosylation in oestrogen-treated males as well as females. In all three clinical categories in RA, pregnancy also induced a continuous increase in the degree of branching of the glycans of AGP. However, similar changes in concentration and fucosylation were only found during remission of the disease symptoms. In the relapse and unchanged categories in RA, the degree of fucosylation and the plasma concentration of AGP remained constant throughout pregnancy. This indicates a relationship between changes in alpha3-fucosylation of AGP and RA disease activity.