Biomedical subjects

Paul D Robbins

Publications and source records attributed to Paul D Robbins.

At least 37 records · Page 2Linked to original sources

PubMed2005

Adenoviral-mediated transfer of TGF-beta1 but not IGF-1 induces chondrogenic differentiation of human mesenchymal stem cells in pellet cultures.

OBJECTIVE: The objective of the present study was to investigate the potential of application of growth factor genes to induce chondrogenic differentiation of human-derived mesenchymal stem cells (MSCs). The growth factor genes evaluated in the present study were transforming growth factor 1 (TGF-beta1) and insulin-like growth factor 1 (IGF-1). METHODS: Human MSCs were transduced with the adenoviral vectors carrying either TGF-beta1 or IGF-1 (AdTGF-beta1 and AdIGF-1 respectively) or a combination of both growth factor genes at different multiplicities of infection (MOI) and were then made into pellets. Pellets were also made from nontransduced cells and maintained in culture medium supplemented with 10 ng/mL of TGF-beta1. At specified time points, histological analysis, cartilage matrix gene expression, and immunofluorescence were performed to determine the extent of chondrogenic differentiation. RESULTS: MSCs transduced with the AdTGF-beta1 demonstrated robust chondrogenic differentiation, while those made from AdIGF-1 did not. AdTGF-beta1 pellets demonstrated aggrecan gene expression as early as day 3 of pellet culture, while type II collagen gene expression was detected by day 10 of culture. The AdIGF-1, alone or in combination with TGF-beta1 pellets, did not show any type II collagen gene expression at any time point. By immunofluoresecence, type X collagen was distributed throughout the matrix in TGF-beta1 protein pellets while the growth factor gene pellets displayed scant staining. CONCLUSION: The results suggest that sustained administration of TGF-beta1 may be more effective in suppressing terminal differentiation than intermittent dosing and thus effective for cartilage repair.

Adenoviridae↗

PubMed2005

Altered trafficking of Fas and subsequent resistance to Fas-mediated apoptosis occurs by a wild-type p53 independent mechanism in esophageal adenocarcinoma.

BACKGROUND: Decreased cell-surface expression of Fas (CD95) results in resistance to Fas-mediated apoptosis in esophageal adenocarcinoma (EA). Because p53 is known to increase transcription of Fas and also may induce trafficking of the protein to the plasma membrane, we investigated whether the loss of wild-type (wt)-p53 function accounts for our previous findings. MATERIALS AND METHODS: Surgical specimens of Barrett's Esophagus containing areas of dysplasia were immunostained for p53 and Fas protein expression. Three EA cell lines were transfected with a wt-p53 containing adenovirus to examine the effects of p53 overexpression. The p53 status of these EA cell lines was determined by sequence analysis. RESULTS: Regions of dysplasia where p53 protein accumulation was observed corresponded to areas of loss of Fas expression. Sequence analysis of the p53 coding sequence in three EA cell lines (Seg-1, Bic-1, and Flo-1) that retain Fas protein within the cytoplasm, demonstrated that Seg-1 contained wt-p53, but mutations were found in Flo-1 and Bic-1 cell lines. Adenoviral transduction of the cell lines with wt-p53 resulted in cell growth arrest in Seg-1 and Bic-1 and induced cell death in Flo-1, but did not result in an increase in Fas protein expression, cell-surface expression, or restoration of sensitivity to Fas-mediated apoptosis. CONCLUSIONS: These data suggest that decreased cell-surface expression of Fas and resistance to Fas-mediated apoptosis may occur independently of loss of wt p53 expression.

Adenocarcinoma↗

PubMed2005

Dual transduction of insulin-like growth factor-I and interleukin-1 receptor antagonist protein controls cartilage degradation in an osteoarthritic culture model.

This study evaluated the potential of gene induced synoviocyte expression of a combination of insulin-like growth factor-I (AdIGF-I) and interleukin-1 receptor antagonist protein (AdIL-1Ra) to control articular cartilage degradation in vitro. Cartilage explants and synovial membrane were harvested from young mature horses. Synovial monolayers were established and either (1) maintained as untransduced controls; (2) transduced with AdIGF-I at 200 MOI in 500 microl serum-free medium; (3) transduced with AdIL-1Ra at 100 MOI; or (4) transduced with a combination of AdIGF-I (200 MOI) and AdIL-1Ra (100 MOI). Following transduction, cartilage explants were exposed to the synovial monolayer medium using co-culture inserts. Cultures were maintained for 6 days in either serum-free medium or medium containing 10 ng/ml recombinant human interleukin-1beta. At termination, synovial cell RNA was isolated for real-time PCR analysis, and cartilage explants were collected for H&E and toluidine blue staining, immunohistochemistry for type II collagen and IGF-I, in situ localization of IGF-I and type II collagen gene expression, and biochemical assays. Synovial monolayers were readily transduced with both AdIGF-I and AdIL-1Ra. IGF-I and IL-1Ra protein were secreted at beneficial levels throughout the experiment, having peak concentrations of 94.6 ng/ml and 33.0 ng/ml, respectively. Transduction with IGF-I promoted cartilage production of proteoglycan and type II collagen, suggesting a beneficial role for healing injured cartilage. Transduction with IL-1Ra decreased the synovial expression of IL-1alpha and IL-1beta and matrix metalloproteinases, indicating a mechanism for prevention of matrix degradation. The beneficial effects of the combination of anabolic growth factors and catabolic blockers were evident in improved preservation of proteoglycan content of cartilage explants exposed to the depleting effects of IL-1. These results show that gene therapy combining anabolic growth factors to stimulate matrix synthesis and catabolic blockers to prevent matrix degradation by IL-1, protects and causes partial restoration of cartilage matrix, and suggest a potential benefit of combination gene therapy for cartilage healing.

Animals↗

PubMed2005

Human periprosthetic tissues implanted in severe combined immunodeficient mice respond to gene transfer of a cytokine inhibitor.

BACKGROUND: Periprosthetic tissue formation and local inflammation that are associated with wear debris contribute to the pathogenesis of aseptic loosening of a prosthesis. This study evaluated a retrovirus-mediated gene therapy with use of a novel xenograft-based animal model. METHODS: Human periprosthetic tissues obtained from patients during revision arthroplasty performed because of aseptic loosening of a prosthetic joint were transplanted into the left quadriceps and paravertebral muscles of severe combined immunodeficient (SCID) mice. The engrafted tissues were recovered seven, fifteen, or thirty days after implantation for histological and molecular analyses. The periprosthetic tissues were incubated with retroviruses encoding for human interleukin-1 receptor antagonist (hIL-1Ra) or bacteria beta-galactosidase (LacZ) at 37 degrees C for three hours prior to implantation to evaluate their responses to gene modification. RESULTS: The human periprosthetic tissues were well accepted in SCID mice for up to thirty days, with angiogenesis occurring in the majority of the implanted tissue sections. The histological appearance was consistent between the recovered graft tissue and the original donor tissue. Strong expression of interleukin-1, tumor necrosis factor, and interleukin-6 was detected in the xenografts with use of immunohistochemical stains. Histological analysis revealed that interleukin-1 receptor antagonist gene modification significantly decreased the total number of inflammatory cells (p < 0.01) in engrafted human tissue containing implant wear debris. Real-time reverse transcription-polymerase chain reaction and immunohistochemical staining showed declining expression levels of interleukin-1 and tumor necrosis factor following interleukin-1 receptor antagonist gene transfer in comparison with LacZ-transduced or virus-free controls. CONCLUSIONS: Human periprosthetic tissue can survive in the SCID mouse host for up to thirty days and responds to the interleukin-1 receptor antagonist gene transfer with the amelioration of inflammation.

Aged↗

PubMed2004

Gene transfer to the tendon-bone insertion site.

This study investigated whether gene transfer to the tendon-bone insertion site is possible during early tendon-transplant healing using viral vectors. In addition, we evaluated the optimal gene delivery technique for an in vivo adenoviral gene transfer to a tendon-bone insertion site in a bone tunnel. Twenty-six rabbits underwent a bilateral transfer of the flexor digitorum longus tendon into a bone canal in the calcaneus. The animals were divided into two groups. The first group (n=18) received a direct injection of an adenoviral vector carrying the luciferase marker gene into the tendon on the left side, while on the right side the adenoviral vector was first injected into the bone trough and the tendon was later inserted into the trough. The analysis of this experiment showed that over a 4-week period a higher luciferase activity was achieved using the bone trough immersion technique. In the second group (n=8) we therefore used the qualitative marker virus (Ad/-LacZ) with the bone trough immersion technique in order to show the site of gene expression. The histological analysis of this experiment demonstrated the presence of beta-galactosidase positive cells within the tendon-bone interface over a 4-week period. Therefore we showed in the first part of this study that the bone canal provides a more efficient target for direct adenoviral gene delivery than the tendon. In the second part of the study we demonstrated the feasibility of the bone trough immersion technique since sustained gene expression within the tendon-bone interface was obtained for up to 4 weeks. This study has shown the feasibility of gene delivery to the tendon-bone interface and provides the basis for the application adenoviral delivery of growth factor genes to the tendon-bone insertion site.

Adenoviridae↗

PubMed2004

Comparative analysis of dendritic cells transduced with different anti-apoptotic molecules: sensitivity to tumor-induced apoptosis.

BACKGROUND: Tumors develop mechanisms to escape recognition by the immune system. It has recently been demonstrated that tumors cause apoptotic death of key immune cells, including the major antigen-presenting cells, dendritic cells (DC). Elimination of DC from the tumor environment significantly diminishes development of specific immunologic responses. We have recently demonstrated that tumor-induced DC apoptosis could be prevented by overexpression of the anti-apoptotic molecule Bcl-x(L). The aim of this study was to identify extrinsic and intrinsic tumor-induced apoptotic pathways in DC by targeting different anti-apoptotic molecules, including FLIP, XIAP/hILP, dominant-negative procaspase-9 and HSP70. METHODS: Murine bone marrow derived DC were transduced with adenoviral vectors carrying different anti-apoptotic molecules and co-incubated with tumor cells in a Transwell system. Apoptosis of DC was assessed by Annexin V and PI staining. RESULTS: We have demonstrated that adenoviral infection of DC with genes encoding different anti-apoptotic molecules exhibits different degrees of resistance to melanoma-induced apoptosis. Furthermore, we have shown that anti-apoptotic molecules other than the Bcl-2 family of proteins are able to protect DC and prevent tumor-induced apoptosis in DC. CONCLUSIONS: The results show that tumor-induced apoptosis of DC is not limited to the mitochondrial pathway of cell death and open additional possibilities for targeted molecular protection of DC longevity in cancer. Therefore, effective protection of DC from tumor-induced apoptosis may significantly improve the efficacy of DC-based therapies for cancer.

Adenoviridae↗

PubMed2004

The fate of mesenchymal stem cells transplanted into immunocompetent neonatal mice: implications for skeletal gene therapy via stem cells.

To explore the feasibility of skeletal gene and cell therapies, we transduced murine bone marrow-derived mesenchymal stem cells (MSCs) with a retrovirus carrying the enhanced green fluorescent protein and zeocin-resistance genes prior to transplantation into 2-day-old immunocompetent neonatal mice. Whole-body imaging of the recipient mice at 7 days post-systemic cell injection demonstrated a wide distribution of the cells in vivo. Twenty-five days posttransplantation, most of the infused cells were present in the lung as assessed by examination of the cells cultured from the lungs of the recipient mice. The cells persisted in lung and maintained a high level of gene expression and could be recovered from the recipient mice at 150 days after cell transplantation. A significant number of GFP-positive cells were also present in the bones of the recipient mice at 35 days post-cell transplantation. Recycling of the cells recovered from femurs of the recipient mice at 25 days posttransplantation by repeated injections into different neonatal mice resulted in the isolation of a clone of cells that was detected in bone and cartilage, but not in lung and liver after systemic injection. These data demonstrate that MSCs persist in immunocompetent neonatal mice, maintain a high level of gene expression, and may participate in skeletal growth and development of the recipient animals.

Animals↗

PubMed2004

Evaluation of peptide-mediated transduction in human CD34+ cells.

Protein transduction domains (PTDs) have been used increasingly to deliver biologically active agents to a variety of cell types in vitro and in vivo. To define the most effective PTDs for transducing hematopoietic cells, we have screened a panel of PTD peptides in human CD34(+) cells for delivery of a 60-kd marker protein and assessed its impact on phenotypic maintenence in vitro. Compared to the HIV-TAT peptide, most peptide complexes displayed high efficiency in transducing the CD34(+) cells, except for those based on shorter peptides (4R, 4K, and 5RQ). In particular, the arginine homopolymers including 8R, 10R, and 12R, were internalized by the cells to a greater extent than the other PTDs. Transduction was significantly potentiated by preincubation of cells with dextran sulfate. Importantly, colony forming ability and CD34(+) CD38(-) primitive phenotype were not significantly altered in the presence of these peptides during a short-term liquid culture. Together, these data suggest the potential usefulness of arginine homopolymers in hematopoietic stem and progenitor cell manipulations.

Antigens, CD34↗

PubMed2004

Feasibility of percutaneous gene transfer to an atrophic nonunion in a rabbit.

Treatment of atrophic nonunions is a challenge to orthopaedic surgeons. Growth factors potentially are valuable factors for improvement of tissue healing. The use of growth factors, however, is limited by their short half-lives. Gene therapy has the potential to improve the treatment. This study aimed to establish and validate an atrophic nonunion model in a rabbit for the use of a percutaneous in vivo gene therapy protocol. An atrophic tibial nonunion was established in 24 New Zealand White rabbits. Radiologic and histologic followup was for 64 weeks. The rabbit tibias showed no radiologic or histologic signs of healing. In addition, an adenoviral vector carrying a marker gene was injected percutaneously into the nonunion site in 12 rabbits. Expression of the marker gene was assessed for as many as 4 weeks. The percutaneous gene delivery resulted in transgene expression in the nonunion site for as many as 4 weeks. The described model reliably leads to an atrophic tibial nonunion in rabbits. Adenoviral percutaneous gene delivery into the nonunion site is feasible and leads to transgene expression locally for at least 1 month. This study provides investigators with a reliable and reproducible model of an atrophic nonunion.

Adenoviridae↗

PubMed2004

The 2003 Nicolas Andry Award. Orthopaedic gene therapy.

We review progress in the field of orthopaedic gene therapy since the concept of using gene transfer to address orthopaedic problems was initiated approximately 15 years ago. The original target, arthritis, has been the subject of two successful Phase I clinical trials, and additional human studies are pending in rheumatoid arthritis and osteoarthritis. The repair of damaged musculoskeletal tissues also has proved to be a fruitful area of research, and impressive enhancement of bone healing has been achieved in preclinical models. Rapid progress also is being made in the use of gene transfer to improve cartilage repair, ligament healing, and restoration of various additional tissues, including tendon and meniscus. Other applications include intervertebral disc degeneration, aseptic loosening, osteoporosis, genetic diseases, and orthopaedic tumors. Of these various orthopaedic targets of gene therapy, tissue repair is likely to make the earliest clinical impact because it can be achieved with existing technology. Tissue repair may become one of the earliest clinical successes for gene therapy as a whole. Orthopaedics promises to be a leading discipline for the use of human gene therapy.

Animals↗

PubMed2004

Prevalence of neutralizing antibodies to adenoviral serotypes 5 and 35 in the adult populations of The Gambia, South Africa, and the United States.

One of the major limitations of the use of adenoviruses as gene therapy vectors is the existence of preformed immunity in various populations. Recent studies have linked failure of adenoviral gene therapy trials to the presence of antiadenoviral neutralizing antibodies (NAb). Understanding the distribution and specificity of such antibodies will assist in the design of successful recombinant adenoviral gene therapies and vaccines. To assess the prevalence of NAb to adenovirus serotypes 5 and 35 (Ad5 and Ad35), we analyzed serum samples from adult immunocompetent individuals living in The Gambia, South Africa, and the United States by using a neutralization assay. Serum samples were incubated with A549 lung carcinoma cells and adenoviruses encoding enhanced green or yellow fluorescent proteins; results were analyzed by fluorescence microscopy and flow cytometry. Using this technique, we found a high prevalence of NAb against Ad5 in Gambian, South African, and U.S. subjects at both low and high titers. Conversely, all subjects displayed a low prevalence of NAb to Ad35; when present, anti-Ad35 NAb were seen at low titers. Because of the ability of adenoviruses to elicit systemic and mucosal immune responses, Ad35 with its low NAb prevalence appears to be an attractive candidate vector for gene therapy applications.

Adenoviridae↗

PubMed2004

Expression and activity of the CDK inhibitor p57Kip2 in chondrocytes undergoing hypertrophic differentiation.

UNLABELLED: Growth plates of p57-null mice exhibit several abnormalities, including loss of collagen type X (CollX) expression. The phenotypic consequences of p57 expression were assessed in an in vitro model of hypertrophic differentiation. Adenoviral p57 expression was not sufficient for CollX expression but did augment induction of CollX by BMP-2. INTRODUCTION: During hypertrophic differentiation, chondrocytes pass from an actively proliferative state to a postmitotic, hypertrophic phenotype. The induction of growth arrest is a central feature of this phenotypic transition. Mice lacking the cyclin dependent-kinase inhibitor p57Kip2 exhibit several developmental abnormalities including chondrodysplasia. Although growth plate chondrocytes in p57-null mice undergo growth arrest, they do not express collagen type X, a specific marker of the hypertrophic phenotype. This study was carried out to investigate the link between p57 expression and the induction of collagen type X in chondrocytes and to determine whether p57 overexpression is sufficient for the induction of hypertrophic differentiation. MATERIALS AND METHODS: Neonatal rat epiphyseal or growth plate chondrocytes were maintained in an aggregate culture model, in defined, serum-free medium. Protein and mRNA levels were monitored by Western and Northern blot analyses, respectively. Proliferative activity was assessed by fluorescent measurement of total DNA and by 3H-thymidine incorporation rates. An adenoviral vector was used to assess the phenotypic consequences of p57 expression. RESULTS AND CONCLUSIONS: During in vitro hypertrophic differentiation, levels of p57 mRNA and protein were constant despite changes in chondrocyte proliferative activity and the induction of hypertrophic-specific genes in response to bone morphogenetic protein (BMP)-2. Adenoviral p57 overexpression induced growth arrest in prehypertrophic epiphyseal chondrocytes in a dose-dependent manner but was not sufficient for the induction of collagen type X, either alone or when coexpressed with the related CDKI p21Cip1. Similar results were obtained with more mature tibial growth plate chondrocytes. p57 overexpression did augment collagen type X induction by BMP-2. These data indicate that p57-mediated growth arrest is not sufficient for expression of the hypertrophic phenotype, but rather it occurs in parallel with other aspects of the differentiation pathway. Our findings also suggest a contributing role for p57 in the regulation of collagen type X expression in differentiating chondrocytes.

Adenoviridae↗

PubMed2003

Effects of a SARS-associated coronavirus vaccine in monkeys.

The causative agent of severe acute respiratory syndrome (SARS) has been identified as a new type of coronavirus. Here, we have investigated the ability of adenoviral delivery of codon-optimised SARS-CoV strain Urbani structural antigens spike protein S1 fragment, membrane protein, and nucleocapsid protein to induce virus-specific broad immunity in rhesus macaques. We immunised rhesus macaques intramuscularly with a combination of the three Ad5-SARS-CoV vectors or a control vector and gave a booster vaccination on day 28. The vaccinated animals all had antibody responses against spike protein S1 fragment and T-cell responses against the nucleocapsid protein. All vaccinated animals showed strong neutralising antibody responses to SARS-CoV infection in vitro. These results show that an adenoviral-based vaccine can induce strong SARS-CoV-specific immune responses in the monkey, and hold promise for development of a protective vaccine against the SARS causal agent.

Adenoviridae↗

PubMed2003

Peroxidation and externalization of phosphatidylserine associated with release of cytochrome c from mitochondria.

Production of reactive oxygen species (ROS) during apoptosis is associated with peroxidation of phospholipids particularly of phosphatidylserine (PS). The mechanism(s) underlying preferential PS oxidation are not well understood. We hypothesized that cytochrome c (cyt c) released from mitochondria into cytosol acts as a catalyst that utilizes ROS generated by disrupted mitochondrial electron transport for PS oxidation. Selectivity of PS oxidation is achieved via specific interactions of positively charged cyt c with negatively charged PS. To test the hypothesis we employed temporary transfection of Jurkat cells with a pro-apoptotic peptide, DP1, a conjugate consisting of a protein transduction domain, PTD-5, and an antimicrobial domain, KLA [(KLAKLAK)2], known to selectively disrupt mitochondria. We report that treatment of Jurkat cells with DP1 yielded rapid and effective release of cyt c from mitochondria and its accumulation in cytosol accompanied by production of H2O2. Remarkably, this resulted in selective peroxidation of PS while more abundant phospholipids such as phosphatidylcholine (PC) and phosphatidylethanolamine (PE) remained nonoxidized. Neither PTD-5 alone nor KLA alone exerted any effect on PS peroxidation. Redox catalytic involvement of cyt c in PS oxidation was further supported by our data demonstrating that: (i) specific interactions of cyt c with PS resulted in the formation of EPR-detectable protein-centered tyrosyl radicals of cyt c upon its interaction with H2O2 in the presence of PS-containing liposomes, and (ii) integration of cyt c into cytochrome c null (Cyt c -/-) cells or HL-60 cells specifically stimulates PS oxidation in the presence of H2O2 or t-BuOOH, respectively. We further demonstrated that DP1 elicited externalization of PS on the surface of Jurkat cells and enhanced their recognition and phagocytosis by J774A.1 macrophages. Our results are compatible with the hypothesis that catalysis of selective PS oxidation during apoptosis by cytosolic cyt c is important for PS-dependent signaling pathways such as PS externalization and recognition by macrophage receptors.

Apoptosis↗

PubMed2003

Intratumoral delivery of dendritic cells engineered to secrete both interleukin (IL)-12 and IL-18 effectively treats local and distant disease in association with broadly reactive Tc1-type immunity.

Dendritic cells (DCs) were adenovirally engineered to constitutively and durably secrete the potent Th1-biasing cytokines interleukin (IL)-12 (AdIL12DC) and/or IL-18 (AdIL18DC) and evaluated for their ability to promote therapeutic antitumor immunity in murine sarcoma models. Injection of either AdIL12DC or AdIL18DC into day 7 CMS4 or MethA tumors resulted in tumor rejection or slowed tumor growth when compared with control cohorts. Importantly, intratumoral injection with DCs engineered to secrete both IL-12 and IL-18 (AdIL12/IL18DC) resulted in complete and the most acute rejection of any treatment group analyzed. This strategy was also effective in promoting the regression of contralateral, untreated tumors. Both CD4+ and CD8+ T cells were required for tumor rejection. CD8+ splenic T cells from mice treated with AdIL12/IL18DC produced the highest levels of IFN-gamma in response to tumor rechallenge in vitro and displayed the broadest repertoire of Tc1-type reactivity to acid-eluted, tumor-derived peptides among all treatment cohorts. This apparent enhancement in cross-presentation of tumor-associated epitopes in vivo may result from the increased capacity of engineered DCs to kill tumor cells, survive tumor-induced apoptosis, and present immunogenic MHC/tumor peptide complexes to T cells after intratumoral injection. In support of this hypothesis, cytokine gene-engineered DCs expressed higher levels of MHC and costimulatory molecules, as well as Fas ligand and membrane-bound tumor necrosis factor alpha, with the latter markers associated with elevated tumoricidal activity in vitro. Cytokine gene-engineered DCs appeared to have a survival advantage in situ when injected into tumor lesions, to be found in approximation with regions of tumor apoptosis, and to have the capacity to ingest apoptotic tumor bodies. These results support the ability of combined cytokine gene transfer to enhance multiple effector functions mediated by intralesionally injected DCs that may concertedly promote cross-priming and the accelerated immune-mediated rejection of tumors.

Adenoviridae↗

PubMed2003

Targeted inhibition of Stat3 with a decoy oligonucleotide abrogates head and neck cancer cell growth.

The transcription factor signal transducer and activator of transcription 3 (Stat3) is constitutively activated in a variety of cancers including squamous cell carcinoma of the head and neck (SCCHN). Previous investigations have demonstrated that activated Stat3 contributes to a loss of growth control and transformation. To investigate the therapeutic potential of blocking Stat3 in cancer cells, we developed a transcription factor decoy to selectively abrogate activated Stat3. The Stat3 decoy was composed of a 15-mer double-stranded oligonucleotide, which corresponded closely to the Stat3 response element within the c-fos promoter. The Stat3 decoy bound specifically to activated Stat3 and blocked binding of Stat3 to a radiolabeled Stat3 binding element. By contrast, a mutated version of the decoy that differed by only a single base pair did not bind the activated Stat3 protein. Treatment of head and neck cancer cells with the Stat3 decoy inhibited proliferation and Stat3-mediated gene expression, but did not decrease the proliferation of normal oral keratinocytes. Thus, disruption of activated Stat3 by using a transcription factor decoy approach may serve as a novel therapeutic strategy for cancers characterized by constitutive Stat3 activation.

Apoptosis↗

PubMed2003

Adverse effects of adenovirus-mediated gene transfer of human transforming growth factor beta 1 into rabbit knees.

To examine the effect of transforming growth factor (TGF)-beta1 on the regulation of cartilage synthesis and other articular pathologies, we used adenovirus-mediated intra-articular gene transfer of TGF-beta1 to both naïve and arthritic rabbit knee joints. Increasing doses of adenoviral vector expressing TGF-beta1 were injected into normal and antigen-induced arthritis rabbit knee joints through the patellar tendon, with the same doses of an adenoviral vector expressing luciferase injected into the contralateral knees as the control. Intra-articular injection of adenoviral vector expressing TGF-beta1 into the rabbit knee resulted in dose-dependent TGF-beta1 expression in the synovial fluid. Intra-articular TGF-beta1 expression in both naïve and arthritic rabbit knee joints resulted in significant pathological changes in the rabbit knee as well as in adjacent muscle tissue. The observed changes induced by elevated TGF-beta1 included inhibition of white blood cell infiltration, stimulation of glycosaminoglycan release and nitric oxide production, and induction of fibrogenesis and muscle edema. In addition, induction of chondrogenesis within the synovial lining was observed. These results suggest that even though TGF-beta1 may have anti-inflammatory properties, it is unable to stimulate repair of damaged cartilage, even stimulating cartilage degradation. Gene transfer of TGF-beta1 to the synovium is thus not suitable for treating intra-articular pathologies.

Adenoviridae↗

PubMed2003

Natural killer, but not natural killer T, cells play a necessary role in the promotion of an innate antitumor response induced by IL-18.

IL-18 administration promotes innate immunity resulting in significant antitumor effects in multiple murine tumor models. Here, we examined the effector population mediating the innate immunity. Most NK cells and some NKT cells express IL-18Rs without prior stimulation (65% positive in NK cells, 18% positive in NKT cells), though few naive T cells do. In vivo depletion of NK cells, but not NKT cells, using AsGM1 antibody significantly reduces IL-18-induced cytotoxicity. However, NK-like activity of hepatic MNCs for the NK target YAC-1 was present in Valpha 14 NKT cell-deficient animals. Furthermore, administration of rIL-18 greatly reduced B16 pulmonary metastases in vivo in NKT cell-deficient animals. When sorted NK and NKT cells were exposed to IL-18 in vitro, NK cells showed more IFN-gamma production and cytolysis against YAC-1 than NKT cells in response to IL-18. These results are consistent with the notion that NK cells, but not NKT cells, are the major effectors in IL-18-induced innate immunity.

Animals↗