Simultaneously targeting extracellular vesicle trafficking and TGF-β receptor kinase activity blocks signaling hyperactivation and metastasis

Metastasis is the leading cause of cancer-related deaths. Transforming growth factor beta (TGF-β) signaling drives metastasis and is strongly enhanced during cancer progression. Yet, the use of on-target TGF-β signaling inhibitors in the treatment of cancer patients remains unsuccessful, highlighting a gap in the understanding of TGF-β biology that limits the establishment of efficient anti-metastatic therapies. Here, we show that TGF-β signaling hyperactivation in breast cancer cells is required for metastasis and relies on increased small extracellular vesicle (sEV) secretion. Demonstrating sEV's unique role, TGF-β signaling levels induced by sEVs exceed the activity of matching concentrations of soluble ligand TGF-β. Further, genetic disruption of sEV secretion in highly-metastatic breast cancer cells impairs cancer cell aggressiveness by reducing TGF-β signaling to nearly-normal levels. Otherwise, TGF-β signaling activity in non-invasive breast cancer cells is inherently low, but can be amplified by sEVs, enabling invasion and metastasis of poorly-metastatic breast cancer cells. Underscoring the translational potential of inhibiting sEV trafficking in advanced breast cancers, treatment with dimethyl amiloride (DMA) decreases sEV secretion, TGF-β signaling activity, and breast cancer progression in vivo. Targeting both the sEV trafficking and TGF-β signaling by combining DMA and SB431542 at suboptimal doses potentiated this effect, normalizing the TGF-β signaling in primary tumors to potently reduce circulating tumor cells, metastasis, and tumor self-seeding. Collectively, this study establishes sEVs as critical elements in TGF-β biology, demonstrating the feasibility of inhibiting sEV trafficking as a new therapeutic approach to impair metastasis by normalizing TGF-β signaling levels in breast cancer cells.

Crosstalk between Interleukin-1 Receptor-Like 1 and Transforming Growth Factor-β Receptor Signaling Promotes Renal Fibrosis

IL-33, a member of the IL-1 family, acts as an alarmin in immune response. Epithelial-mesenchymal transition and transforming growth factor-β (TGF-β)–induced fibroblast activation are key events in the development of renal interstitial fibrosis. The current study found increased expression of IL-33 and interleukin-1 receptor-like 1 (IL1RL1, alias ST2), the receptor for IL-33, in human fibrotic renal tissues. In addition, IL-33– or ST2-deficient mice showed significantly reduced levels of fibronectin, α-smooth muscle actin, and vimentin, and increased E-cadherin levels. In HK-2 cells, IL-33 promotes the phosphorylation of the TGF-β receptor (TGF-βR), Smad2, and Smad3, and the production of extracellular matrix (ECM), with reduced expression of E-cadherin. Blocking TGF-βR signaling or suppressing ST2 expression impeded Smad2 and Smad3 phosphorylation, thereby reducing ECM production, suggesting that IL-33–induced ECM synthesis requires cooperation between the two pathways. Mechanistically, IL-33 treatment induced a proximate interaction between ST2 and TGF-βRs, activating downstream Smad2 and Smad3 for ECM production in renal epithelial cells. Collectively, this study identified a novel and essential role for IL-33 in promoting TGF-β signaling and ECM production in the development of renal fibrosis. Therefore, targeting IL-33/ST2 signaling may be an effective therapeutic strategy for renal fibrosis.

Anti-PD-L1/TGFβR2 (M7824) fusion protein induces immunogenic modulation of human urothelial carcinoma cell lines, rendering them more susceptible to immune-mediated recognition and lysis

BACKGROUND

Avelumab has recently been approved by the Food and Drug Administration for the therapy of Merkel cell carcinoma and urothelial carcinoma. M7824 is a novel first-in-class bifunctional fusion protein comprising a monoclonal antibody against programmed death-ligand 1 (PD-L1, avelumab), fused to the extracellular domain of human transforming growth factor beta (TGFβ) receptor 2, which functions as a TGFβ "trap." Advanced urothelial tumors have been shown to express TGFβ, which possesses immunosuppressive properties that promote cancer progression and metastasis. The rationale for a combined molecule is to block the PD-1/PD-L1 interaction between tumor cells and immune cell infiltrate and simultaneously reduce or eliminate TGFβ from the tumor microenvironment. In this study, we explored the effect of M7824 on invasive urothelial carcinoma cell lines.

METHODS

Human urothelial (transitional cell) carcinoma cell lines HTB-4, HTB-1, and HTB-5 were treated with M7824, M7824mut (M7824 that is mutated in the anti-PD-L1 portion of the molecule and thus does not bind PD-L1), anti-PD-L1 (avelumab), or IgG1 isotype control monoclonal antibody, and were assessed for gene expression, cell-surface phenotype, and sensitivity to lysis by TRAIL, antigen-specific cytotoxic T lymphocytes and natural killer cells.

RESULTS

M7824 retains the ability to mediate antibody-dependent cellular cytotoxicity of tumor cells, although in some cases to a lesser extent than anti-PD-L1. However, compared to anti-PD-L1, M7824 increases (A) gene expression of molecules involved in T-cell trafficking in the tumor (e.g., CXCL11), (B) TRAIL-mediated tumor cell lysis, and (C) antigen-specific CD8+ T-cell-mediated lysis of tumor cells.

CONCLUSIONS

These studies demonstrate the immunomodulatory properties of M7824 on both tumor cell phenotype and immune-mediated lysis. Compared to anti-PD-L1 or M7824mut, M7824 induces immunogenic modulation of urothelial carcinoma cell lines, rendering them more susceptible to immune-mediated recognition and lysis. These findings show the relevance of the dual blockade of PD-L1 and TGFβ in urothelial carcinoma cell lines and thus support the rationale for future clinical studies of M7824 in patients with urothelial cancer.

Evaluation of a special combination of glucan with organic selenium derivative in different murine tumor models

β-glucans are well-established immunomodulators with strong effects resulting in slowing or even inhibiting cancer growth. Recent studies have repeatedly suggested that the biological activities of β-glucan can be potentiated by the addition of other bioactive agents. In the current study, we focused on the anticancer effects of a combination of yeast-derived β-glucan and a selenium-linked pseudodisaccharide. Using three different models of murine cancer, we showed that this combination strongly suppressed the growth of all three types of cancers, most likely via the interaction with natural anticancer antibodies.

Systemic delivery of an oncolytic adenovirus expressing soluble transforming growth factor-β receptor II-Fc fusion protein can inhibit breast cancer bone metastasis in a mouse model

We have investigated whether systemic delivery of an oncolytic adenovirus, Ad.sTβRFc, expressing the soluble form of transforming growth factor-β receptor II fused with human immunoglobulin Fc fragment (sTGFβRIIFc), could inhibit breast cancer bone metastasis in a mouse model. MDA-MB-231 (human breast cancer) cells were inoculated into the left heart ventricles of nude mice. Once the skeletal tumors were visible by X-rays, mice were intravenously injected with either buffer, Ad.sTβRFc, Ad(E1⁻).sTβRFc (a replication-deficient adenovirus expressing sTGFβRIIFc), or Ad.luc2 (a replicating adenovirus expressing firefly luciferase gene). On days 2 and 7 after viral injections, viral replication and sTGFβRIIFc expression were detected in the skeletal tumors in Ad.sTβRFc-treated group; only viral replication in Ad.luc2 group, and sTGFβRIIFc expression in the Ad(E1⁻).sTβRFc group, were detected. To examine the therapeutic effects, buffer or various viral vectors were administered on days 4 and 7 after intracardiac injection of MDA-MB-231 cells. On day 28, X-ray radiography showed a highly significant reduction in lesion size by Ad.sTβRFc, a significant reduction by Ad.luc2, and some reduction by Ad(E1⁻).sTβRFc. Goldner's trichrome and hematoxylin-eosin staining of the bone sections revealed a significant reduction of tumor burden in the Ad.sTβRFc group, but not in the Ad(E1⁻).sTβRFc or Ad.luc2 group. There were significant reductions in free calcium levels by Ad.sTβRFc, Ad(E1⁻).sTβRFc, and Ad.luc2; however, only in the Ad.sTβRFc group were calcium levels reduced to the normal values. These results suggest that concomitant viral replication and sTGFβRIIFc production are important to inhibit bone metastasis and osteolysis, and that Ad.sTβRFc could be developed for targeting breast cancer bone metastases.

Carcinoembryonic antigen interacts with TGF-{beta} receptor and inhibits TGF-{beta} signaling in colorectal cancers

As a tumor marker for colorectal cancers, carcinoembryonic antigen (CEA) enhances the metastatic potential of cancer cells. CEA functions as an intercellular adhesion molecule and is upregulated in a wide variety of human cancers. However, the molecular mechanisms by which CEA mediates metastasis remain to be understood. Transforming growth factor-β (TGF-β) signaling regulates both tumor suppression and metastasis, and also contributes to the stimulation of CEA transcription and secretion in colorectal cancer cells. However, it remains unknown whether CEA, in turn, influences TGF-β functions and if a regulatory cross-talk exists between CEA and the TGF-β signaling pathway. Here, we report that CEA directly interacts with TGF-β receptor and inhibits TGF-β signaling. Targeting CEA with either CEA-specific antibody or siRNA rescues TGF-β response in colorectal cancer cell lines with elevated CEA, thereby restoring the inhibitory effects of TGF-β signaling on proliferation. CEA also enhances the survival of colorectal cancer cells in both local colonization and liver metastasis in animal study. Our study provides novel insights into the interaction between CEA and TGF-β signaling pathway and establishes a negative feedback loop in amplifying the progression of colon cancer cells to more invasive phenotypes. These findings offer new therapeutic opportunities to inhibit colorectal cancer cell proliferation by cotargeting CEA in promoting tumor-inhibitory action of the TGF-β pathway.

Induction of TGF-beta 1, not regulatory T cells, impairs antiviral immunity in the lung following bone marrow transplant

Patients receiving hematopoietic stem cell transplantation or bone marrow transplantation (BMT) as therapy for various malignancies or autoimmune diseases have an increased risk for infectious complications posttransplant, especially in the lung. We have used BMT in mice and murine gammaherpesvirus, gammaHV-68, to study the efficacy of adaptive immune responses post-BMT. Five weeks posttransplant, mice have fully reconstituted their hematopoietic lineages in both the lung and periphery. When challenged with virus, however, BMT mice have a reduced ability to clear lytic virus from the lung. Defective viral control in BMT mice is not related to impaired leukocyte recruitment or defective APC function. Rather, BMT mice are characterized by defective CD4 cell proliferation, skewing of effector CD4 T cells from a Th1 to a Th17 phenotype, and an immunosuppressive lung environment at the time of infection that includes overexpression of TGF-beta1 and PGE(2) and increased numbers of regulatory T cells. Neither indomethacin treatment to block PG synthesis nor anti-CD25 depletion of regulatory T cells improved antiviral host defense post-BMT. Transplanting mice with transgenic bone marrow expressing a dominant-negative TGF-betaRII under the permissive CD4 promoter created mice in which effector CD4 and CD8 cells were unresponsive to TGF-beta1. Mice with TGF-beta1-nonresponsive effector T cells had restored antiviral immunity and improved Th1 responses post-BMT. Thus, our results indicate that overexpression of TGF-beta1 following myeloablative conditioning post-BMT results in impaired effector T cell responses to viral infection.

Development of oncolytic adenovirus armed with a fusion of soluble transforming growth factor-beta receptor II and human immunoglobulin Fc for breast cancer therapy

We have developed an approach to cancer gene therapy in which the oncolytic effects of an adenoviral vector have been combined with selective expression of a soluble form of transforming growth factor (TGF)-beta receptor II fused with Fc (sTGFbetaRIIFc). We chose to use adenoviral dl01/07 mutant because it can replicate in all cancer cells regardless of their genetic defects. An oncolytic adenovirus expressing sTGFbetaRIIFc (Ad.sT- betaRFc) was constructed by homologous recombination. Infection of MDA-MB-231 and MCF-7 human breast cancer cells with Ad.sTbetaRFc produced sTGFbetaRIIFc, which was released into the media. The conditioned media containing sTGFbetaRIIFc could bind with TGF-beta 1 and inhibited TGF-beta-dependent transcription in target cells. Infection of MDA-MB-231, MCF-7, and 76NE human breast cancer cells with Ad.sTbetaRFc resulted in high levels of viral replication, comparable to that of a wild-type dl309 virus. Although some viral replication was observed in actively dividing normal human lung fibroblasts, there was no replication in nonproliferating normal cells. Direct injection of Ad.sTbetaRFc into MDA-MB-231 human breast xenograft tumors grown in nude mice resulted in a significant inhibition of tumor growth, causing tumor regression in more than 85% of the animals. These results indicate that it is possible to construct an oncolytic virus expressing sTGFbetaRIIFc in which both viral replication and transgene expression remain intact, and the recombinant adenovirus is oncolytic in a human tumor xenograft model. On the basis of these results we believe that it may be feasible to develop a cancer gene therapy approach using Ad.sTbetaRFc as an antitumor agent.

Evidence for a role of transforming growth factor (TGF)-beta1 in the induction of postglomerular albuminuria in diabetic nephropathy: amelioration by soluble TGF-beta type II receptor

Transforming growth factor-beta (TGF-beta) has previously been implicated in the progression of diabetic nephropathy, including the onset of fibrosis and albuminuria. Here we report for the first time the use of a high-affinity TGF-beta1 binding molecule, the soluble human TGF-beta type II receptor (sTbetaRII.Fc), in the treatment of diabetic nephropathy in 12-week streptozotocin-induced diabetic Sprague-Dawley rats. In vitro studies using immortalized rat proximal tubule cells revealed that 50 pmol/l TGF-beta1 disrupted albumin uptake (P < 0.001 vs. control), an inhibition significantly reversed by the use of the sTbetaRII.Fc (1,200 pmol/l). In vivo studies demonstrated that treatment with sTbetaRII.Fc reduced urinary albumin excretion by 36% at 4 weeks, 59% at 8 weeks (P < 0.001), and 45% at 12 weeks (P < 0.01 for diabetic vs. treated). This was correlated with an increase in megalin expression (P < 0.05 for diabetic vs. treated) and a reduction in collagen IV expression following sTbetaRII.Fc treatment (P < 0.001 for diabetic vs. treated). These changes occurred independently of changes in blood glucose levels. This study demonstrates that the sTbetaRII.Fc is a potential new agent for the treatment of fibrosis and albuminuria in diabetic nephropathy and may reduce albuminuria by reducing TGF-beta1-induced disruptions of renal proximal tubule cell uptake of albumin.

Adenoviral-mediated TGF-β1 inhibition in a mouse model of myelofibrosis inhibit bone marrow fibrosis development

Myelofibrosis is characterized by excessive deposits of extracellular matrix proteins, which occur as a marrow microenvironment reactive response to cytokines released from the clonal malignant myeloproliferation. The observation that mice exposed to high systemic levels of thrombopoietin (TPO) invariably developing myelofibrosis has allowed demonstration of the crucial role of transforming growth factor (TGF)-beta1 released by hematopoietic cells in the onset of myelofibrosis. The purpose of this study was to investigate whether TGF-beta1 inhibition could directly inhibit fibrosis development in a curative approach of this mice model. An adenovirus encoding for TGF-beta1 soluble receptor (TGF-beta-RII-Fc) was injected either shortly after transplantation (preventive) or 30 days post-transplantation (curative). Mice were transplanted with syngenic bone marrow cells transduced with a retrovirus encoding for murine TPO. All mice developed a myeloproliferative syndrome. TGF-beta-RII-Fc was detected in the blood of all treated mice, leading to a dramatic decrease in TGF-beta1 level. Histological analysis show that the two approaches (curative or preventive) were successful enough to inhibit bone marrow and spleen fibrosis development in this model. However, lethality of TPO overexpression was not decreased after treatment, indicating that in this mice model, myeloproliferation rather than fibrosis was probably responsible for the lethality induced by the disorder.

Use of the Transforming Growth Factor-??1 Inhibitor Peptide in Periprosthetic Capsular Fibrosis: Experimental Model with Tetraglycerol Dipalmitate

BACKGROUND

Capsular contracture is the most common specific complication associated with silicone prostheses. It is thought to be caused by the gradual retraction of the fibrous scar tissue that forms around the prosthesis. Molecular biology has made it possible to determine the role of transforming growth factor beta (TGF-beta) in the scar physiopathology of any fibrotic process, including periprosthetic capsular fibrosis. The effects on the inhibition of TGF-beta have also been demonstrated in experimental models of scar formation and fibrosis, which opens the way for new therapeutic alternatives in the treatment of capsular contracture.

METHODS

Three experimental groups of 10 rats each were formed to evaluate periprosthetic fibrosis after its modulation with a newly synthesized TGF-beta1 peptide inhibitor in a tetraglycerol dipalmitate matrix. In the first group, subcutaneously and submuscularly placed, smooth, solid silicone prostheses were left untreated; in the second group, the prostheses were left after being immersed in a solution of tetraglycerol dipalmitate; and in the third group, following the same protocol as in the second group, the solution contained tetra-glycerol dipalmitate mixed with the inhibitor peptide of TGF-beta1. The animals were euthanized 8 weeks after implantation, and the capsules were assessed both macroscopically and histologically.

RESULTS

Inhibition of capsular thickness and cellularity was significantly more effective in the group of animals treated with the inhibitor peptide of TGF-beta1.

CONCLUSIONS

The TGF-beta1 inhibitor peptide applied in a matrix with tetraglycerol dipalmitate is significantly effective in achieving a reduction in periprosthetic fibrosis after placement of silicone implants, either subcutaneously or submuscularly. This result suggests new therapeutic approaches.

Soluble type II transforming growth factor-beta receptor inhibits established murine malignant mesothelioma tumor growth by augmenting host antitumor immunity

PURPOSE

Transforming growth factor (TGF)-beta blockade has been proposed as an anticancer therapy; however, understanding which tumor patients might benefit most from such therapy is crucial. An ideal target of such inhibitory therapy might be malignant mesothelioma (MM), a highly lethal, treatment-resistant malignancy of mesothelial cells of the pleura and peritoneum that produces large amounts of TGF-beta. The purpose of this study was to explore the possible therapeutic utility of TGF-beta blockade on MM.

EXPERIMENTAL DESIGN

To evaluate this hypothesis, we tested the effects of a soluble TGF-beta type II receptor (sTGF-beta R) that specifically inhibits TGF-beta1 and TGF-beta 3 in three different murine MM tumor models, AB12 and AC29 (which produce large amounts of TGF-beta) and AB1 (which does not produce TGF-beta).

RESULTS

Tumor growth of both established AB12 and AC29 tumors was inhibited by sTGF-beta R. In contrast, AB1 tumors showed little response to sTGF-beta R. The mechanism of these antitumor effects was evaluated and determined to be primarily dependent on immune-mediated responses because (a) the antitumor effects were markedly diminished in severe combined immunodeficient mice or mice depleted of CD8(+) T cells and (b) CD8(+) T cells isolated from spleens of mice treated with sTGF-beta R showed strong antitumor cytolytic effects, whereas CD8(+) T cells isolated from spleens of tumor-bearing mice treated with of control IgG2a showed no antitumor cytolytic effects.

CONCLUSIONS

Our data suggest that TGF-beta blockade of established TGF-beta-secreting MM should be explored as a promising strategy to treat patients with MM and other tumors that produce TGF-beta.

Transforming the TGFbeta pathway: convergence of distinct lead generation strategies on a novel kinase pharmacophore for TbetaRI (ALK5)

The pathological activation of the transforming growth factor beta (TGFbeta) pathway plays a critical role in the progression of fibrotic diseases and also enhances tumor invasiveness and metastasis. Due to its central role in TGFbeta signaling, the TGFbeta type I receptor (TbetaRI) is emerging as an exciting target for blockade of the TGFbeta pathway. In this review we will discuss how three independent drug discovery strategies, ie, target-hopping, high-throughput screening and virtual screening, have converged in the identification of inhibitors of TalphaRI kinase. Structural studies have provided insight into the potency and selectivity of these inhibitors and form the basis for structure-based design optimization strategies. These efforts have enabled the production of potent, selective inhibitors for dissecting the TGFalpha pathway and assessing the usefulness of TalphaRI blockade in the treatment of fibrotic diseases and cancer.

[Inhibiting scar formation in rat cutaneous wounds by blocking TGF-beta signaling]

OBJECTIVE

TGF-beta plays a key role in wound scarring. This study explored the possibility of using gene therapy to inhibit wound scarring by blocking TGF-beta signaling.

METHODS

In vitro, human normal dermal fibroblasts were infected with recombinant adenoviruses of truncated TGF-beta receptor II (tTGF-betaRII, 100 pfu/cell) and beta-galactosidase (beta-gal, 100 pfu/cell), and their effects on regulating TGF-beta1 gene expression were analyzed by Northern blot. For gene therapy, beta-gal and tTGF-betaRII viruses (1 x 10(9) pfu)were injected intradermally at left and right side of dorsal skin of newborn Sprague-Dawley rats (n = 15) respectively. A full-thickness incisional wound (0.5 cm long) was created at the injection sites of each rat 2 days post-injection. An incisional wound was similarly created in the middle part of the dorsal skin of tTGF-betaRII transgenic mice (n = 5) and control mice (n = 5). Wound tissues of rats and mice were harvested at various time points post-wounding for histological and immunohistochemical analysis. Scar area in tissue section was measured by Image-Pro Plus software.

RESULTS

Over-expression of tTGF-betaRII markedly reduced TGF-beta1 gene expression in dermal fibroblasts. Adenovirus mediated gene expression in skin reached a peak level 2 - 3 days post-injection, and decreased gradually at 5 - 7 days. Two weeks post-wounding, histology and quantitative analysis demonstrated that relative scar area in the wounds of transgenic mice and control mice were 136,969.8 +/- 66,339 and 474,641.6 +/- 227,396 respectively, the scar area of transgenic wounds was 29 percent of control area (P < 0.05). In all rats, wounds transfected with tTGF-betaRII gene healed with much less scarring (relative scar area 128,311.2 +/- 36,764.6) than control wounds (251,189.1 +/- 62,544.7) of the same rat, with a 45% reduction of scar area in average (P < 0.001). In addition, the tTGF-betaRII expression also decreased inflammation and TGF-beta1 production in treated wounds, and promoted the repair of panniculus muscle in treated wounds.

CONCLUSIONS

Adenovirus mediated over-expression of tTGF-betaRII can block TGF-beta signaling and inhibit wound scarring, and thus can serve as a gene therapy strategy to control wound scarring.

Effects of delayed treatment with transforming growth factor-beta soluble receptor in a three-dose bleomycin model of lung fibrosis in hamsters

Transforming growth factor-beta (TGF-beta) plays a pivotal role in an exaggerated synthesis and accumulation of collagen in fibrotic disorders of many organs. We have previously demonstrated that repeated intratracheal (IT) instillation of TGF-beta soluble receptor (TR) in hamsters markedly decreased the bleomycin (BL)-induced lung fibrosis in response to a single dose. The present study was carried out in a 3-dose BL-hamster model of lung fibrosis to better evaluate the therapeutic potential of TR. Three doses of BL (2.5, 2.0, and 1.5 U/4 mL/kg) or an equivalent volume of isotonic saline was administered IT consecutively at weekly intervals, and phosphate-buffered saline (PBS) or TR (4 nmol/0.3 mL/hamster) by the same route twice a week, starting after the 2nd BL or 3rd BL dose. Twenty-one days after the 3rd dose of BL instillation, the hamsters were killed for bronchoalveolar lavage (BAL) and biochemical and histopathological analyses. The results showed that treatment with TR starting after either the 2nd or 3rd dose of BL caused significant reduction in BL-induced lung fibrosis, as demonstrated by marked decreases in the hydroxyproline level and prolyl hydroxylase activity of the lungs. Histopathological evaluation of the lungs also revealed that the hamsters in both BL+TR groups had markedly fewer fibrotic lesions than hamsters in BL+PBS group. These results demonstrate the beneficial effects of delayed treatment with TR in attenuating the progression of ongoing fibrotic process and suggest its potential therapeutic uses in the management of lung fibrosis in humans.

Adapting a transforming growth factor beta-related tumor protection strategy to enhance antitumor immunity

Transforming growth factor beta (TGF-beta), a pleiotropic cytokine that regulates cell growth and differentiation, is secreted by many human tumors and markedly inhibits tumor-specific cellular immunity. Tumors can avoid the differentiating and apoptotic effects of TGF-beta by expressing a nonfunctional TGF-beta receptor. We have determined whether this immune evasion strategy can be manipulated to shield tumor-specific cytotoxic T lymphocytes (CTLs) from the inhibitory effects of tumor-derived TGF-beta. As our model we used Epstein-Barr virus (EBV)-specific CTLs that are infused as treatment for EBV-positive Hodgkin disease but that are vulnerable to the TGF-beta produced by this tumor. CTLs were transduced with a retrovirus vector expressing the dominant-negative TGF-beta type II receptor HATGF-betaRII-Deltacyt. HATGF-betaRII-Deltacyt- but not green fluorescence protein (eGFP)-transduced CTLs was resistant to the antiproliferative and anticytotoxic effects of exogenous TGF-beta. Additionally, receptor-transduced cells continued to secrete cytokines in response to antigenic stimulation. TGF-beta receptor ligation results in phosphorylation of Smad2, and this pathway was disrupted in HATGF-betaRII-Deltacyt-transduced CTLs, confirming blockade of the signal transduction pathway. Long-term expression of TGF-betaRII-Deltacyt did not affect CTL function, phenotype, or growth characteristics. Tumor-specific CTLs expressing HATGF-betaRII-Deltacyt should have a selective functional and survival advantage over unmodified CTLs in the presence of TGF-beta-secreting tumors and may be of value in treatment of these diseases.

[Cytokines in rheumatoid arthritis. II. Anti-inflammatory cytokines]

In this review the role of anti-inflammatory cytokines in the pathogenesis of rheumatoid arthritis is presented. We describe their expression in synovial tissue, synovial fluid and in serum and correlation with disease activity. Special attention was paid to the possibilities of the alternative therapies modifying the balance of cytokine network, in the rheumatoid arthritis patients, towards anti-inflammatory state. Several such approaches have shown significant clinical benefits with mild side effects.

Reduction of bleomycin induced lung fibrosis by transforming growth factor beta soluble receptor in hamsters

BACKGROUND

Transforming growth factor beta (TGF-beta) is a key mediator of collagen synthesis in the development of lung fibrosis. It has previously been shown that the administration of TGF-beta antibody and TGF-beta binding proteoglycan, decorin, reduced bleomycin (BL) induced lung fibrosis in animals. The present study was carried out to investigate whether intratracheal instillation of TGF-beta soluble receptor (TR) would minimise the BL induced lung fibrosis in hamsters.

METHODS

The effect of a recombinant TR (TGFbetaRII) on the lung collagen accumulation was evaluated in a BL hamster model of pulmonary fibrosis. Animals were divided into four groups and intratracheally injected with saline or BL at 6.5 U/4 ml/kg followed by intratracheal instillation of phosphate buffered saline (PBS) or 4 nmol TR in 0.3 ml twice a week. Twenty days after the first intratracheal instillation the hamsters were killed for bronchoalveolar lavage (BAL) fluid, biochemical, and histopathological analyses.

RESULTS

Treatment of hamsters with TR after intratracheal instillation of BL significantly reduced BL induced lung fibrosis as shown by decreases in the lung hydroxyproline level and prolyl hydroxylase activity, although they were still significantly higher than those of the saline control. Histopathological examination showed a considerable decrease in BL induced fibrotic lesions by TR treatment. However, TR did not prevent the BL induced increases in total cells and protein in the BAL fluid.

CONCLUSIONS

These results suggest that TR has antifibrotic potential in vivo and may be useful in the treatment of fibrotic diseases where increased TGF-beta is associated with excess collagen accumulation.

Tumorigenicity of mouse thymoma is suppressed by soluble type II transforming growth factor beta receptor therapy

Many types of tumor cells overexpress transforming growth factor beta (TGF-beta), which is believed to promote tumor progression. We hypothesized that overexpression of the extracellular region of the type II TGF-beta receptor (soluble TbetaRII) would compete for or block TGF-beta binding to TbetaRs on immune cells, preventing TGF-beta-mediated immunosuppression and consequently resulting in the eradication of tumor cells. We tested this in the mouse thymoma cell line EL4, which has been reported to suppress cellular immunity by secreting a large amount of TGF-beta. Transduction of EL4 with recombinant retrovirus encoding soluble TbetaRII resulted in the secretion of heterogeneously glycosylated, 25 to 35 kDa truncated TbetaRII. Inoculation of 1 x 10(4) to 5 x 10(4) soluble TbetaRII-modified EL4 cells (EL4/Ts, EL4 cells transduced with recombinant retrovirus encoding soluble TbetaRII and neomycin resistance gene) s.c. to mice showed reduced tumorigenicity, as indicated by lower overall tumor incidence (7%, 1 of 14; P < 0.001) compared with unmodified EL4 (100%, 9 of 9) or vector-modified EL4 cells (EL4/neo, EL4 cells transduced with recombinant retrovirus encoding neomycin resistance gene; 100%, 4 of 4). Administration of mitomycin C-treated EL4/Ts cells (1 x 10(6)) after EL4 inoculation (1 x 10(4)) reduced tumor incidence from 100% (5 of 5 in mice inoculated with mitomycin C-treated EL4/neo) to 40% (4 of 10, P < 0.05), indicating that supply of soluble TbetaRII could actually block TGF-beta-mediated tumorigenesis. In vitro tumor cytotoxicity assays revealed 3-5-fold higher cytotoxic activity with lymphocytes from EL4/Ts-bearing mice compared with those from EL4- or EL4/neo-bearing mice, indicating that the observed tumor rejection was mediated by restoration of the tumor-specific cellular immunity. These data suggest that expression of soluble TbetaRII is an effective strategy for treating highly progressive tumors secreting TGF-beta.