Magnus Lindvall

Expression of TGF‐β isoforms, TGF‐β receptors, and SMAD molecules at different stages of human glioma

Human gliomas express TGF‐β but, so far the expression of downstream mediators has been investigated in only a few cell lines. We have examined tissue specimens of 23 gliomas: 3 astrocytomas grade II (AST), 8 anaplastic astrocytomas grade III (AAST), and 12 glioblastoma multiforme grade IV (GBM). We analyzed the mRNA expression of TGF‐β1, TGF‐β2, TGF‐β3, the TGF‐β receptors type I (TβR‐I) and type II (TβR‐II), Smad2, Smad3, and Smad4. mRNA expression of IL‐10 and CD95 (FAS/APO‐1) were also studied. We detected increased mRNA levels of the 3 TGF‐β isoforms, correlating with the degree of malignancy. TGF‐β3 mRNA was increased, particularly in AST and AAST, while TGF‐β1 and TGF‐β2 mRNAs were strongly expressed in GBM. TGF‐β normally up‐regulates the TGF‐β receptors, and TβR‐I and TβR‐II showed stronger expression in all gliomas when compared to normal tissues. However, the mRNA expression of Smad2, Smad3, and Smad4 was decreased in GBM. IL‐10 mRNA expression was detected in glioma tissues but not in glioma cell lines. No marked increase in the expression of soluble CD95 splicing variants was found in the gliomas compared with normal tissue. However, total CD95 mRNA was elevated among GBM tissues. Int. J. Cancer 89:251–258, 2000.

Neural Progenitor Cell Lines Inhibit Rat Tumor Growth in Vivo

Current therapies for gliomas often fail to address their infiltrative nature. Conventional treatments leave behind small clusters of neoplastic cells, resulting in eventual tumor recurrence. In the present study, we have evaluated the antitumor activity of neural progenitor cells against gliomas when stereotactically injected into nucleus Caudatus of Fisher rats. We show that the rat neural progenitor cell lines HiB5 and ST14A, from embryonic hippocampus and striatum primordium, respectively, are able to prolong animal survival and, in 25% of the cases, completely inhibit the outgrowth of N29 glioma compared with control animals. Delayed tumor outgrowth was also seen when HiB5 cells were inoculated at the site of tumor growth 1 week after tumor inoculation or when a mixture of tumor cells and HiB5 cells were injected s.c. into Fisher rats. HiB5 cells were additionally coinoculated together with two alternative rat gliomas, N32 and N25. N32 was growth inhibited, but rats inoculated with N25 cells did not show a prolonged survival. To evaluate the possibility of the involvement of the immune system in the tumor outgrowth inhibition, we show that HiB5 cells do not evoke an immune response when injected into Fisher rats. Furthermore, the rat neural progenitor cells produce all transforming growth factor β isotypes, which could explain the observed immunosuppressive nature of these cells. Hence, some neural progenitor cells have the ability to inhibit tumor outgrowth when implanted into rats. These results indicate the usefulness of neural stem cells as therapeutically effective cells for the treatment of intracranial tumors.

Immunization with mutagen-treated (tum-) cells causes rejection of nonimmunogenic rat glioma isografts.

The ethyl-N-nitrosourea-induced rat glioma N32 was treated with the mutagenic compoundN-methyl-N′-nitro-N-nitrosoguanidine and the surviving cells cloned by limiting dilution. Out of 20 clones tested 8 did not produce tumors subcutaneously even after challenge doses 3 log units above the minimal tumor dose for N32. All of 5 clones grew in a retarded manner intracerebrally but produced tumors in some animals. Preimmunizations with three of the rejected clones (tum−) gave protection against subcutaneous and intracerebral isografts of the unmutated N32. This effect could be enhanced if the cells used for immunizations were pretreated with interferon γ (IFNγ) for 48 h. If immunizations were started subsequent to challenge, only immunization with one of two tested tum− clones pretreated with IFNγ induced significant rejection against intracerebral N32 isografts. Both N32 and its tum− closes were MHC class I positive and MHC class II negative. IFNγ treatment enhanced the MHC class I expression with 20%–90% on the tum− clones and with 40% on N32. MHC class II expression could be induced on N32 cells after 7 days of IFNγ treatment but not on any of the tum− clones tested. We conclude that the enhancing effect of IFNγ treatment on tumor isograft rejection may depend on up-regulation of MHC class I but not of MHC class II. This investigation demonstrates that it is possible to induce rejection of weakly immunogenic intracerebral brain tumors by immunization with selected highly immunogenic tumor cell mutants. In conjunction with relevant cytokines, the cross-protective effect of these tum− variants might be further enhanced and serve as a model for immunotherapy against malignant human brain tumors.

Lithium in Drinking Water and Thyroid Function

Background High concentrations of lithium in drinking water were previously discovered in the Argentinean Andes Mountains. Lithium is used worldwide for treatment of bipolar disorder and treatment-resistant depression. One known side effect is altered thyroid function. Objectives We assessed associations between exposure to lithium from drinking water and other environmental sources and thyroid function. Methods Women (n = 202) were recruited in four Andean villages in northern Argentina. Lithium exposure was assessed based on concentrations in spot urine samples, measured by inductively coupled plasma mass spectrometry. Thyroid function was evaluated by plasma free thyroxine (T4) and pituitary gland thyroid-stimulating hormone (TSH), analyzed by routine immunometric methods. Results The median urinary lithium concentration was 3,910 μg/L (5th, 95th percentiles, 270 μg/L, 10,400 μg/L). Median plasma concentrations (5th, 95th percentiles) of T4 and TSH were 17 pmol/L (13 pmol/L, 21 pmol/L) and 1.9 mIU/L, (0.68 mIU/L, 4.9 mIU/L), respectively. Urine lithium was inversely associated with T4 [β for a 1,000-μg/L increase = −0.19; 95% confidence interval (CI), −0.31 to −0.068; p = 0.002] and positively associated with TSH (β = 0.096; 95% CI, 0.033 to 0.16; p = 0.003). Both associations persisted after adjustment (for T4, β = −0.17; 95% CI, −0.32 to −0.015; p = 0.032; for TSH: β = 0.089; 95% CI, 0.024 to 0.15; p = 0.007). Urine selenium was positively associated with T4 (adjusted T4 for a 1 μg/L increase: β = 0.041; 95% CI, 0.012 to 0.071; p = 0.006). Conclusions Exposure to lithium via drinking water and other environmental sources may affect thyroid function, consistent with known side effects of medical treatment with lithium. This stresses the need to screen for lithium in all drinking water sources.

Instructive cross-talk between neural progenitor cells and gliomas

Gliomas are the most common primary brain tumors and offer a poor prognosis in patients because of their infiltrative and treatment‐resistant nature. The median survival time after diagnosis is approximately 11–12 months. There is a strong need for novel treatment modalities in targeting gliomas, and recent advances use neural progenitor cells as delivery systems for different therapeutic strategies. In this study, we show that rat embryonic neural progenitor cell (NPC) lines, transplanted at a distant site from a 3‐day‐preestablished glioma in the striatum, were able to migrate toward and colocalize with tumor isles without general spread into the brain parenchyma. Upon encounter with tumor, neural progenitor cells changed phenotype and became vimentin positive. These results demonstrate that transplanted neural progenitor cells respond to queues from a tumor and home to and exert an antitumor effect on the preestablished glioma, significantly decreasing the tumor volume with approximately 67% compared with control tumors after 1–2 weeks. Moreover, these early effects could be translated into increased survival times of animals treated with neural progenitor cell grafts 3 days after intrastriatal tumor inoculation. In contrast, there was no activation or migration of endogenous subventricular zone (SVZ) neuroblasts in response to an intrastriatal syngeneic tumor. In conclusion, NPC possess the ability to influence tumor growth as well as respond to queues from the tumor or tumor microenvironment, demonstrating a cross‐talk between the cells.

Transforming growth factor-beta1, a strong costimulator of rat T-cell activation promoting a shift towards a Th2-like cytokine profile

TGF-beta is a known regulator of hematopoietic cells. In this study we suggest a major role of adherent spleen cells (adh-splc), to convert an inhibitory effect of TGF-beta1 on T-cell activation into a stimulatory effect. We show that interaction of TGF-beta1 with adh-splc induces a costimulatory effect on T-cell proliferation. This costimulatory signal requires the adh-splc to be in physical contact with the T-cells. Presence of adh-splc results in a shift towards a Th2-like response with a cytokine profile of increased IL-10 and decreased IFN-gamma. In the adh-splc population the increase of IL-10 is most pronounced at start of activation, whereas in the T-lymphocyte population, IL-10 increases at the end of culture. The suppression of the IFN-gamma production by TGF-beta1 is shown to be an important mechanism by which TGF-beta enhances proliferation of Th2 lymphocytes.

The three isoforms of transforming growth factor-beta co-stimulate rat T cells and inhibit lymphocyte apoptosis

In this study the three different mammalian isoforms of transforming growth factor‐β (TGF‐β) were compared with regard to their effect on the response of rat T lymphocytes to the superantigen, staphylococcal enterotoxin A (SEA). All different isozymes were found to increase the proliferative response of rat T lymphocytes, which was accompanied by a significantly lower percentage of apoptotic cells than proliferation in the absence of TGF‐β. The same effect of TGF‐β was observed on the generation of apoptotic cells in an allo response (mixed lymphocyte reaction). TGF‐β2 and TGF‐β3 were three to 10‐fold more potent than TGF‐β1 as co‐stimulators of T lymphocytes, and equal in decreasing the percentage of apoptotic T cells. TGF‐β1 reduced the frequency and the number of cells undergoing apoptosis in T cells and, to an even higher degree, among B lymphocytes. TGF‐β did not seem to affect the production of the apoptosis inducer, tumour necrosis factor‐α (TNF‐α), neither at the mRNA level nor at the protein level. Neutralizing antibodies against the cytokine, TNF‐α, decreased the percentage of apoptotic cells among T cells responding to SEA, both in the absence and in the presence of added TGF‐β1. Thus, when TGF‐β acts as a co‐stimulator for T‐cell activation it inhibits the induction of apoptosis and sustains the number of viable cells.

Search for effective therapy against glioblastoma multiforme - Clinical immunisation with autologous glioma cells transduced with the human interferon-gamma gene

Based upon earlier experimental work by our group, we have started a human immuno-gene therapy study. The goal is to study the effects of immunisation with autologous tumour cells expressing gene sequences for human interferon-gamma For more than two decades we have sought for efficient treatment against malignant gliomas. Our most successful treatment in the animal models is immuno-gene therapy where murine genes for the cytokines IFN-gamma, IL-7 and B7-1 were chosen for their ability to stimulate different stages of the pathway for cytotoxic T lymphocyte (CTL) activation. Rats of the syngeneic inbred strain Fischer 344 had rat glioma cells of the N32 line inoculated in the right caudate nucleus, and 1 or 3 days later N32 cells transfected with either IFN-gamma, IL-7 or B7-1 genes were injected subcutaneously (and in some studies intraperitoneally). This treatment was repeated three to four times with 7- to 14-day interval and resulted in significantly improved survival compared with treatment with wild-type rat glioma cells (e.g. not transfected with the cytokine genes). The continued work concentrated on treatment with IFN-gamma secreting tumour cells of both the N32 line and also a newly developed ENU-induced rat glioma cell line called N29. This work proved the effectiveness of the technique. Cure was achieved in 72% of the animals treated with the IFN-gamma cells. Tumour-infiltrating leukocytes from N32-IFN-gamma-immunised animals showed a significantly stronger infiltration by CD8+ T-cells, significantly more NK cells, and an increased number of CD25-expressing T-cells. These results confirmed the possible usefulness of IFN-gamma-transfected tumour cells in the immune-therapy of rat brain tumours. The animal experiments have motivated us to start a human immuno-gene therapy study including 20 patients with glioblastoma multiforme (GBM), where >80% of the tumour can be surgically removed. The goal is to ascertain whether immunisation with autologous tumour cells expressing gene sequences for human interferon-gamma is safe for the patients, gives rise to an immunological response, and adds any beneficial effect to conventional therapy (tumour growth, prolonged survival). Hitherto, nine patients have been included in the study, two of which have received 6 and 10 immunisations, respectively. Two patients have died from their disease before cells have been ready for immunisation; in two cases no malignant cells have appeared in the cell cultures and three patients are ready to start their immunisation shortly. The immunisation takes place in the dermis of the upper arm. Seven days after each immunisation, a skin biopsy is taken from the centre of one of the injection sites. The composition of the cellular infiltration in the skin is studied by markers for T lymphocytes (CD3); helper cells, subset of T cells (CD4); killer cells, subset of T cells (CD8); natural killer cells (CD16) and B lymphocytes, B cells (CD20). Also the expression of cytokines for functional T cell subsets are studied: IL-2, IL-4, IL-10, IL-12, IL-18, TNF-alpha and IF-gamma and TGF-beta(1,2 and 3-) Peripheral blood is sampled both before and after operation and also after each immunisation event. Co-culture of this blood with tumour cells from the patient allows for a selection of T-cells that can recognise tumour-specific antigens. The results from the first human treatments are presented

MONOCYTE-DEPENDENT COSTIMULATORY EFFECT OF TGF-BETA 1 ON RAT T-CELL ACTIVATION

TGF‐β1 is known to have suppressive effects on both T‐cell proliferation and effector functions, but costimulatory effects have also been reported. In the present investigation the effect of TGF‐β1 is studied in vitro on T‐cell proliferative responses of rat spleen cells and of lymph node cells to alloantigens (MLR), the superantigen Staphylococcal enterotoxin A (SEA) or IL‐2. Without addition of TGF‐β1, adherent, freshly isolated rat spleen monocytes have a suppressive effect on T‐cell activation, which upon addition of TGF‐β1 is reversed to a strong costimulatory effect. The costimulatory effect of TGF‐β1 is shown to be entirely dependent on the presence of fresh monocytes. Costimulation is demonstrated when TGF‐β1 is added to spleen cells at the start of the in vitro assays but not when added more than 24 h after the start. Costimulation is not demonstrable when TGF‐β1 is added to lymph node cells alone but is readily detectable after admixture of freshly isolated spleen monocytes to the lymph node cells. TGF‐β1 added at the end of culture induces suppression of T‐cell activation irrespective of the presence or absence of monocytes. When TGF‐β1 is added both at the start of an MLC and again after 4 days, the costimulatory effect is maintained, although somewhat moderated. The costimulatory effect of TGF‐β1 is demonstrated as an increase of the T blast cell population of both CD4+ IL‐2R+ and CD8+ IL‐2R+ T‐cell subsets, whereas the suppressive effect of TGF‐β1 is shown as reduction of the same parameters.

Inhibition of rat yolk sac tumour growth in vivo by a monoclonal antibody to the retroviral molecule P15E

SummaryA monoclonal mouse IgG2b antibody 19F8, directed towards a determinant on the retroviral transmembranous molecule p15E, binds selectively to certain rat tumours, including all tested yolk sac tumours, one rat colon carcinoma, one spontaneous kidney carcinoma and an adenovirus-type-9-induced rat breast tumour, as tested by antibody-dependent cellular cytotoxicity (ADCC) and immunohistochemistry. Groups of rats receiving yolk sac tumour F56 isografts intraperitoneally (i.p.) or subperitoneally (s.p.) were treated with this monoclonal antibody (mAb), 19F8, inoculated twice a week in doses of 100 µg. Parallel control groups received analogous inoculations of an isotype-matched monoclonal antibody. A significant growth inhibitory effect was observed with 19F8. In 5/10 rats isografted i.p., tumour outgrowth was completely inhibited and in the other 5 rats the outgrowth was delayed compared to the 10 rats in the control group, which all developed tumours. All rats of the control group developed large volumes of ascites, whereas the 5 rats in the therapy group with eventual tumour outgrowth had little or no ascites. In two experiments with rats carrying subperitoneal isografts and treated with the 19F8 mAb, tumour grew out in 4/5 and 5/10 rats, though growth was delayed compared to the control groups, in which 5/5 and 9/9 rats developed tumours. The tumours grew significantly more slowly in the therapy groups compared to the controls. All rats that developed tumours in the therapy groups showed an anti-idiotypic response against mAb 19F8. The single tumour-free rat in the first experiment and 1/5 tumour-free rats in the other showed no such response. The draining lymph node cells from the tumour-free animals showed a specific proliferative response to yolk sac tumour F56 cells in a mixed lymphocyte tumour cell culture (MLTC), and the MLTC-induced cells were cytotoxic to F56 but not to the natural-killer-sensitive rat T cell lymphoma G1—Tc1. The cytotoxic cell population was more than 90% CD4+. It is concluded that the two test systems for identification of the epitope of p15E detected by mAb 19F8 correlated well in detection of the epitope in the cells (immunohistochemistry) and at the cell surface (ADCC). It is also concluded that mAb 19F8 has a growth-inhibitory effect on yolk sac tumour F56 and that, as a result of the treatment, T cells with specificity for F56 are appearing in draining lymph nodes of tumour-free animals.