Inflammation-induced recombinant protein expression in vivo using promoters from acute-phase protein genes

An adenoviral vector encoding an inflammation-inducible antagonist, HMGB1 Box A, as a novel therapeutic approach to inflammatory diseases

Influenza, as well as other respiratory viruses, can trigger local and systemic inflammation resulting in an overall "cytokine storm" that produces serious outcomes such as acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). We hypothesized that gene therapy platforms could be useful in these cases if the production of an anti-inflammatory protein reflects the intensity and duration of the inflammatory condition. The recombinant protein would be produced and released only in the presence of the inciting stimulus, avoiding immunosuppression or other unwanted side effects that may occur when treating infectious diseases with anti-inflammatory drugs. To test this hypothesis, we developed AdV.C3-Tat/HIV-Box A, an inflammation-inducible cassette that remains innocuous in the absence of inflammation but releases HMGB1 Box A, an antagonist of high mobility group box 1 (HMGB1), in response to inflammatory stimuli such as lipopolysaccharide (LPS) or influenza virus infection. We report here that this novel inflammation-inducible HMGB1 Box A construct in a non-replicative adenovirus (AdV) vector mitigates lung and systemic inflammation therapeutically in response to influenza infection. We anticipate that this strategy will apply to the treatment of multiple diseases in which HMGB1-mediated signaling is a central driver of inflammation.IMPORTANCEMany inflammatory diseases are mediated by the action of a host-derived protein, HMGB1, on Toll-like receptor 4 (TLR4) to elicit an inflammatory response. We have engineered a non-replicative AdV vector that produces HMGB1 Box A, an antagonist of HMGB1-induced inflammation, under the control of an endogenous complement component C3 (C3) promoter sequence, that is inducible by LPS and influenza in vitro and ex vivo in macrophages (Mϕ) and protects mice and cotton rats therapeutically against infection with mouse-adapted and human non-adapted influenza strains, respectively, in vivo. We anticipate that this novel strategy will apply to the treatment of multiple infectious and non-infectious diseases in which HMGB1-mediated TLR4 signaling is a central driver of inflammation.

Select Porcine Elongation Factor 1α Sequences Mediate Stable High-Level and Upregulated Expression of Heterologous Genes in Porcine Cells in Response to Primate Serum

Genetically engineered (GE) pigs with various combinations of genetic profiles have been developed using heterologous promoters. This study aimed to identify autologous promoters for high and ubiquitous expression of xenotransplantation relevant genes in GE pigs. A 1.4 kb upstream regulatory sequence of porcine elongation factor 1α (pEF1α) gene was selected and isolated for use as a promoter. Activity of the pEF1α promoter was subsequently compared with that of the cytomegalovirus (CMV) promoter, CMV enhancer/chicken β-actin (CAG) promoter, and human EF1α (hEF1α) promoter in different types of pig-derived cells. Comparative analysis of luciferase and mutant human leukocyte antigen class E-F2A-β-2 microglobulin (HLA-E) expression driven by pEF1α, CMV, CAG, and hEF1α promoters revealed the pEF1α promoter mediated comparable expression levels with those of the CAG promoter in porcine ear skin fibroblasts (PEFs) and porcine kidney-15 (PK-15) cells, but lower than those of the CAG promoter in porcine aortic endothelial cells (PAECs). The pEF1α promoter provided long-term stable HLA-E expression in PEFs, but the CAG promoter failed to sustain those levels of expression. For xenogeneic serum-induced cytotoxicity assays, the cells were cultured for several hours in growth medium supplemented with primate serum. Notably, the pEF1α promoter induced significant increases in luciferase and HLA-E expression in response to primate serum in PAECs compared with those driven by the CAG promoter, suggesting the pEF1α promoter could regulate temporal expression of heterologous genes under xenogeneic-cytotoxic conditions. These results suggest the pEF1α promoter may be valuable for development of GE pigs spatiotemporally and stably expressing immunomodulatory genes for xenotransplantation.

The role of SOCS3 in the hypothalamic paraventricular nucleus in rat model of inflammatory pain

Background

Inflammatory molecular signals are modulated by a variety of intracellular transduction pathways, the activation of which may induce and amplify the spread of inflammatory response. Suppresser of cytokine signaling 3 (SOCS3) is an established negative feedback regulation transcription factor associated with tumor, diabetes mellitus, inflammation and anaphylaxis. Herein, we investigated whether SOCS3 in the paraventricular nucleus (PVN) can attenuate pro-inflammatory responses, and thereby relieve the inflammatory pain.

Methods

Adeno-associated virus (AAV) overexpressing SOCS3 was pre-injected into the PVN. Three weeks later, rat model of chronic inflammatory pain was established via subcutaneous injection of complete Freund's adjuvant (CFA) into the plantar center of hind paws. The therapeutic effect of SOCS3 was tested by the measurement of thermal and mechanical allodynia. In mechanistic study, the protein level of SOCS3 was evaluated by Western blotting, and the expression of c-fos and Iba-1 were assessed by immunofluorescent staining.

Results

Inflammatory pain was associated with upregulated interleukin 6 (IL-6) and SOCS3 in PVN in the acute phase. Thermal hyperalgesia can be relieved by intra-PVN injection of IL-6 neutralizing antibody (NA). Meanwhile, the upregulated c-fos and microglial activation was reversed. Furthermore, SOCS3 expression in PVN was downregulated in the chronic phase. Intra-PVN injection of AAV overexpressing SOCS3 suppressed the activation of neurons and attenuated thermal hyperalgesia and mechanical allodynia.

Conclusion

Inhibition of IL-6 signaling attenuated inflammatory hyperalgesia in the acute phase. SOCS3 overexpression in the PVN attenuated inflammatory pain in the chronic phase via suppression of neuronal activation.

Development of a Chimeric Model to Study and Manipulate Human Microglia In Vivo

iPSC-derived microglia offer a powerful tool to study microglial homeostasis and disease-associated inflammatory responses. Yet, microglia are highly sensitive to their environment, exhibiting transcriptomic deficiencies when kept in isolation from the brain. Furthermore, species-specific genetic variations demonstrate that rodent microglia fail to fully recapitulate the human condition. To address this, we developed an approach to study human microglia within a surrogate brain environment. Transplantation of iPSC-derived hematopoietic-progenitors into the postnatal brain of humanized, immune-deficient mice results in context-dependent differentiation into microglia and other CNS macrophages, acquisition of an ex vivo human microglial gene signature, and responsiveness to both acute and chronic insults. Most notably, transplanted microglia exhibit robust transcriptional responses to Aβ-plaques that only partially overlap with that of murine microglia, revealing new, human-specific Aβ-responsive genes. We therefore have demonstrated that this chimeric model provides a powerful new system to examine the in vivo function of patient-derived and genetically modified microglia.

Inflammation-induced transgene expression in genetically engineered equine mesenchymal stem cells

BACKGROUND

Osteoarthritis, a chronic and progressive degenerative joint disorder, ranks amongst the top five causes of disability. Given the high incidence, associated socioeconomic costs and the absence of effective disease-modifying therapies of osteoarthritis, cell-based treatments offer a promising new approach. Owing to their paracrine, differentiation and self-renewal abilities, mesenchymal stem cells (MSCs) have great potential for regenerative medicine, which might be further enhanced by targeted gene therapy. Hence, the development of systems allowing transgene expression, particularly when regulated by natural disease-dependent occuring substances, is of high interest.

METHODS

Bone marrow-isolated equine MSCs were stably transduced with an HIV-1 based lentiviral vector expressing the luciferase gene under control of an inducible nuclear factor κB (NFκB)-responsive promoter. Marker gene expression was analysed by determining luciferase activity in transduced cells stimulated with different concentrations of interleukin (IL)-1β or tumour necrosis factor (TNF)α.

RESULTS

A dose-dependent increase in luciferase expression was observed in transduced MSCs upon cytokine stimulation. The induction effect was more potent in cells treated with TNFα compared to those treated with IL-1β. Maximum transgene expression was obtained after 48 h of stimulation and the same time was necessary to return to baseline luciferase expression levels after withdrawal of the stimulus. Repeated cycles of induction allowed on-off modulation of transgene expression without becoming refractory to induction. The NFκB-responsive promoter retained its inducibility also in chondrogenically differentiated MSC/Luc cells.

CONCLUSIONS

The results of the present study demonstrate that on demand transgene expression from the NFκB-responsive promoter using naturally occurring inflammatory cytokines can be induced in undifferentiated and chondrogenically differentiated equine MSCs. Copyright © 2016 John Wiley & Sons, Ltd.

Proteomic analysis of silica hybrid sol-gel coatings: a potential tool for predicting the biocompatibility of implants in vivo

The interactions of implanted biomaterials with the host organism determine the success or failure of an implantation. Normally, their biocompatibility is assessed using in vitro tests. Unfortunately, in vitro and in vivo results are not always concordant; new, effective methods of biomaterial characterisation are urgently needed to predict the in vivo outcome. As the first layer of proteins adsorbed onto the biomaterial surfaces might condition the host response, mass spectrometry analysis was performed to characterise these proteins. Four distinct hybrid sol-gel biomaterials were tested. The in vitro results were similar for all the materials examined here. However, in vivo, the materials behaved differently. Six of the 171 adsorbed proteins were significantly more abundant on the materials with weak biocompatibility; these proteins are associated with the complement pathway. Thus, protein analysis might be a suitable tool to predict the in vivo outcomes of implantations using newly formulated biomaterials.

Characterization of serum proteins attached to distinct sol-gel hybrid surfaces

The success of a dental implant depends on its osseointegration, an important feature of the implant biocompatibility. In this study, two distinct sol-gel hybrid coating formulations [50% methyltrimethoxysilane: 50% 3-glycidoxypropyl-trimethoxysilane (50M50G) and 70% methyltrimethoxysilane with 30% tetraethyl orthosilicate (70M30T)] were applied onto titanium implants. To evaluate their osseointegration, in vitro and in vivo assays were performed. Cell proliferation and differentiation in vitro did not show any differences between the coatings. However, four and eight weeks after in vivo implantation, the fibrous capsule area surrounding 50M50G-implant was 10 and 4 times, respectively, bigger than the area of connective tissue surrounding the 70M30T treated implant. Thus, the in vitro results gave no prediction or explanation for the 50M50G-implant failure in vivo. We hypothesized that the first protein layer adhered to the surface may have direct implication in implant osseointegration, and perhaps correlate with the in vivo outcome. Human serum was used for adsorption analysis on the biomaterials, the first layer of serum proteins adhered to the implant surface was analyzed by proteomic analysis, using mass spectrometry (LC-MS/MS). From the 171 proteins identified; 30 proteins were significantly enriched on the 50M50G implant surface. This group comprised numerous proteins of the immune complement system, including several subcomponents of the C1 complement, complement factor H, C4b-binding protein alpha chain, complement C5 and C-reactive protein. This result suggests that these proteins enriched in 50M50G surface might trigger the cascade leading to the formation of the fibrous capsule observed. The implications of these results could open up future possibilities to predict the biocompatibility problems in vivo. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1477-1485, 2018.

Assembly PCR synthesis of optimally designed, compact, multi-responsive promoters suited to gene therapy application

Gene therapy has the potential to provide innovative treatments for genetic and non-genetic diseases, with the ability to auto-regulate expression levels of therapeutic molecules so that they are produced locally and in direct response to disease activity. Generating disease responsive gene therapy vectors requires knowledge of the activation profile of transcription factors (TFs) during active disease, in order to assemble binding sites for these TFs into synthetic promoters, which can be appropriately activated by the disease process. In this study, we optimised a PCR random assembly approach to generate promoters with optimal spacing between TF binding sites (TFBSs) and their distance from the TATA box. In promoters with optimal spacing, it was possible to demonstrate activation by individual transcription pathways and either additive or synergistic promoter activation when transfected cells were treated with combined stimuli. The kinetics and sensitivity of promoter activation was further explored in transduced cells and when lentivirus was directly delivered to mouse paws a synthetic promoter demonstrated excellent activation by real-time imaging in response to local inflammation.

Optimization of a nonviral transfection system to evaluate Cox-2 controlled interleukin-4 expression for osteoarthritis gene therapy in vitro

BACKGROUND

Gene therapy appears to have the potential for achieving a long-term remedy for osteoarthritis (OA). However, there is a risk of adverse reactions, especially when using cytomegalovirus-controlled expression. To provide a safe application, we focused on the expression of therapeutic cytokines [e.g. interleukin (IL)-4] in a disease-responsive manner by use of the previously cloned Cox-2 promoter as 'genetic switch'. In the present study, we report the functionality of a controlled gene therapeutic system in an equine osteoarthritic cell model.

METHODS

Different nonviral transfection reagents were tested for their efficiency on equine chondrocytes stimulated with equine IL-1β or lipopolysaccharide to create an inflammatory environment. To optimize the transfection, we successfully redesigned the vector by excluding the internal ribosomal entry site (IRES). The functionality of our Cox-2 promoter construct with respect to expressing IL-4 was proven at the mRNA and protein levels and the anti-inflammatory potential of IL-4 was confirmed by analyzing the expression of IL-1β, IL-6, IL-8, matrix metalloproteinase (MMP)-1, MMP-3 and tumor necrosis factor (TNF)-α using a quantitative polymerase chain reaction.

RESULTS

Nonviral transfection reagents yielded transfection rates from 21% to 44% with control vectors with and without IRES, respectively. Stimulation of equine chondrocytes resulted in a 20-fold increase of mRNA expression of IL-1β. Such exogenous stimulation of chondrocytes transfected with pNCox2-IL4 led to an increase of IL-4 mRNA expression, whereas expression of inflammatory mediators decreased. The timely link between these events confirms the anti-inflammatory potential of synthesized IL-4.

CONCLUSIONS

We consider that this approach has significant potential for translation into a useful anti-inflammation therapy. Molecular tools such as the described therapeutic plasmid pave the way for a local-controlled, self-limiting gene therapy.

Inducible expression of enhanced green fluorescent protein by interleukin-1α, interleukin-1β and Toll-like receptor 2 promoters in goat mammary epithelial cells in response to bacterial challenges

The development of a bacteria-inducible expression system has several advantages compared with persistent expression of anti-bacterial proteins in milk to prevent and treat mastitis. The present study determined whether mastitis responsive promoters could regulate enhanced green fluorescent protein (EGFP) expression in goat mammary epithelial cells (GMECs) in response to challenges with Escherichia coli, Staphylococcus aureus or Streptococcus agalactiae. The level of expression of interleukin (IL)-1α was significantly increased in GMECs challenged with E. coli, S. aureus or S. agalactiae compared with untreated GMECs. IL-1β was induced by E. coli and S. aureus, while Toll-like receptor 2 (TLR2) was induced by E. coli only. GMECs were transfected with IL-1α, IL-1β and TLR2 promoter-EGFP reporter gene lentiviral expression vectors and the levels of expression of EGFP were measured by flow cytometry and Western blot analysis after bacterial challenge. EGFP expression driven by the IL-1α and IL-1β promoters was higher in GMECs challenged with E. coli, S. aureus or S. agalactiae than in untreated GMECs. There were no differences in EGFP expression driven by the TLR2 promoter between GMECs challenged with S. aureus or S. agalactiae and untreated GMECs, but EGFP expression was significantly increased in GMECs challenged with E. coli. Overall, these results indicate that the promoters of some bacteria-inducible genes can regulate EGFP expression in GMECs in response to bacterial challenges. This bacteria-inducible expression strategy could be used for production of mastitis resistant animals by regulating the expression of anti-bacterial proteins in the mammary gland.

Immunomodulatory effect of chinese herbal medicine formula sheng-fei-yu-chuan-tang in lipopolysaccharide-induced acute lung injury mice

Traditional Chinese medicine formula Sheng-Fei-Yu-Chuan-Tang (SFYCT), consisting of 13 medicinal plants, was used to treat patients with lung diseases. This study investigated the immunoregulatory effect of SFYCT on intratracheal lipopolysaccharides- (LPS-) challenged acute lung injury (ALI) mice. SFYCT attenuated pulmonary edema, macrophages, and neutrophils infiltration in the airways. SFYCT decreased inflammatory cytokines, including tumor necrosis factor-α (TNFα), interleukin-1β, and interleukin-6 and inhibited nitric oxide (NO) production but increased anti-inflammatory cytokines, interleukin-4, and interleukin-10, in the bronchoalveolar lavage fluid of LPS-challenged mice. TNFα and monocyte chemotactic protein-1 mRNA expression in the lung of LPS-challenged mice as well as LPS-stimulated lung epithelial cell and macrophage were decreased by SFYCT treatment. SFYCT treatment also decreased the inducible nitric oxide synthase expression and phosphorylation of nuclear factor-κB (NF-κB) in the lung of mice and macrophage with LPS stimulation. SFYCT treatment dose dependently decreased the LPS-induced NO and reactive oxygen species generation in LPS-stimulated macrophage. In conclusion, SFYCT attenuated lung inflammation during LPS-induced ALI through decreasing inflammatory cytokines production while increasing anti-inflammatory cytokines production. The immunoregulatory effect of SFYCT is related to inhibiting NF-κB phosphorylation.

Human skin mast cells express complement factors C3 and C5

We examine whether complement factor C3 or C5 is synthesized by human skin-derived mast cells and whether their synthesis is regulated by cytokines. C3 and C5 mRNAs were assessed by RT-PCR, and proteins by flow cytometry, confocal microscopy, Western blotting, and ELISA. C3 and C5 mRNAs were each expressed, and baseline protein levels/10(6) cultured mast cells were 0.9 and 0.8 ng, respectively, and located in the cytoplasm outside of secretory granules. C3 accumulated in mast cell culture medium over time and by 3 d reached a concentration of 9.4 ± 8.0 ng/ml, whereas C5 levels were not detectable (<0.15 ng/ml). Three-day incubations of mast cells with IL-1α, IL-1β, IL-17, IFN-γ, IL-6, or anti-FcεRI did not affect C3 protein levels in culture medium, whereas incubations with PMA, TNF-α, IL-13, or IL-4 enhanced levels of C3 1.7- to 3.3-fold. In contrast with C3, levels of C5 remained undetectable. Importantly, treatment with TNF-α together with either IL-4 or IL-13 synergistically enhanced C3 (but not C5) production in culture medium by 9.8- or 7.1-fold, respectively. This synergy was blocked by attenuating the TNF-α pathway with neutralizing anti-TNF-α Ab, soluble TNFR, or an inhibitor of NF-κB, or by attenuating the IL-4/13 pathway with Jak family or Erk antagonists. Inhibitors of PI3K, Jnk, and p38 MAPK did not affect this synergy. Thus, human mast cells can produce and secrete C3, whereas β-tryptase can act on C3 to generate C3a and C3b, raising the likelihood that mast cells engage complement to modulate immunity and inflammation in vivo.

Adenoviral targeting of gene expression to tumors

Using biochemical, imaging and histological methods, we employed transcriptional targeting to increase the specificity of tumor gene expression in vivo for intravenously administered recombinant adenovirus vectors. Surprisingly, the relative specificity of tumor expression in comparison to other tissues was increased for a constitutively expressing recombinant adenovirus, AdCMVLuc, by simply reducing the viral dose. Even at lower doses, however, the high frequency of viral infection and transgene expression in the liver using constitutive promoters still represents a substantial problem. To further augment tumor specificity, we constructed a series of adenoviruses expressing luciferase from several other promoters and tested their ability to selectively transcribe genes in tumor cells both in vitro and in vivo. Constitutively active viral promoters (RSV, SRα) varied widely in their tumor selectivity, but hypoxia-responsive promoters (carbonic anhydrase 9, PAI-1, SOD2, and several chimeric constructs) demonstrated the most tumor-selective expression. Our results show that tumor targeting to HT1080 fibrosarcomas was readily achieved using transcriptional targeting mechanisms. We attribute the relatively high level of gene transfer and expression in HT1080 tumors in vivo to increased viral access to the tumor, presumably due to discontinuities in tumor vasculature and augmented expression from stress-responsive promoters in the hypoxic and inflammatory tumor microenvironment.

Computational design and application of endogenous promoters for transcriptionally targeted gene therapy for rheumatoid arthritis

The promoter regions of genes that are differentially regulated in the synovial membrane during the course of rheumatoid arthritis (RA) represent attractive candidates for application in transcriptionally targeted gene therapy. In this study, we applied an unbiased computational approach to define proximal-promoters from a gene expression profiling study of murine experimental arthritis. Synovium expression profiles from progressing stages of collagen-induced arthritis (CIA) were classified into six distinct groups using k-means clustering. Using an algorithm based on local over-representation and comparative genomics, we identified putatively functional transcription factor-binding sites (TFBS) in TATA-dependent proximal-promoters. Applying a filter based on spacing between TATA box and transcription start site (TSS) combined with the presence of over-represented nuclear factor kappaB (NFkappaB), AP-1, or CCAAT/enhancer-binding protein beta (C/EBPbeta) sites, 382 candidate murine and human promoters were reduced to 66, corresponding to 45 genes. In vitro, 9 out of 10 computationally defined promoter regions conferred cytokine-inducible expression in murine cells and human synovial fibroblasts. Under these conditions, the serum amyloid A3 (Saa3) promoter showed the strongest transcriptional induction and strength. We applied this promoter for driving therapeutically efficacious levels of the interleukin-1 receptor antagonist (Il1rn) in a disease-regulated fashion. These results demonstrate the value of bioinformatics for guiding the selection of endogenous promoters for transcriptionally targeted gene therapy.

Application of a disease-regulated promoter is a safer mode of local IL-4 gene therapy for arthritis

The application of disease-regulated promoters in local gene therapy for rheumatoid arthritis potentiates the development of a sophisticated treatment that relies on a restricted and fine-tuned supply of biologicals. Although several studies have investigated regulated promoters for achieving effective transgene expression during arthritis, none have explored their potential for minimizing deleterious effects arising from constitutive overexpression of transgenes under naive conditions. Using naive and collagen-induced arthritic mice, we examined the applicability of a hybrid interleukin-1 enhancer/interleukin-6 proximal promoter for achieving efficacious murine interleukin-4 gene therapy under arthritic conditions, while minimizing interleukin-4-induced inflammation under naive conditions. We found strong upregulation of transgene expression in virally transduced knee joints under arthritic conditions compared to levels in naive animals. Besides its responsiveness, the promoter strength proved sufficient for generating therapeutically efficacious levels interleukin-4, as demonstrated by the successful protection against cartilage erosion in collagen-induced arthritis. Most importantly, promoter-mediated restriction of the potent chemotactic interleukin-4 in naive animals strongly reduced the amounts of inflammatory cell influx. This study suggests the suitability of the interleukin-1 enhancer/interleukin-6 proximal promoter for the development of a local gene therapy strategy for rheumatoid arthritis that requires fine-tuned and restricted expression of transgenes with a pleiotrophic nature.

Protective and immunomodulatory effect of Gingyo-san in a murine model of acute lung inflammation

To investigate the effects of Gingyo-san (GGS), the traditional Chinese medicinal formula, on the acute lung inflammation induced by LPS in vivo, mice were challenged with intratracheal LPS before treatment with GGS or vehicle. In lung morphology, GGS reduced the infiltration of activated polymorphonuclear neutrophils in the airways, decreased pulmonary edema, reduced nitrosative stress, and improved lung morphology. ELISA or RT-PCR detected the expression of cytokines in BALF and lung tissue. The mechanism of these benefits by treatment with GGS including attenuating expression TNFalpha, IL-1 beta, IL-6, KC, MCP-1, MIP-2, iNOS, and activation of nuclear factor (NF-kappaB and AP-1) in BALF and lung tissue. Particularly, GGS also enhanced the anti-inflammatory cytokine (IL-10) and limited the acute lung inflammation. Therefore, its protection activity against LPS-induced lung inflammatory mediators release might be beneficial in the treatment of endotoxin-associated inflammation.

The immunomodulation of endotoxin-induced acute lung injury by hesperidin in vivo and in vitro

To investigate the modulation of lung local immune responses of hesperidin (HES) on the acute lung inflammation induced by LPS in vivo. Mice were challenged with intratracheal lipopolysaccharide (100 microg) 30 min before with treatment hesperidin (200 mg/kg oral administration) or vehicle. After 4 and 24 h, bronchoalveolar lavage fluid was obtained to measure proinflammatory (TNF-alpha, IL-1 beta, IL-6), anti-inflammatory (IL-10, IL-4, IL-12) cytokines, chemokines (KC, MCP-1 and MIP-2), total cell counts, nitric oxide production, and proteins. Lung histology was performed in inflated-fixed lungs. Hesperidin downregulate the LPS-induced expression of TNF-alpha, IL-1 beta, IL-6, KC, MIP-2, MCP-1, and IL-12. It also enhanced the production of IL-4, IL-10. Total leukocyte counts; nitric oxide production, iNOS expression, and proteins were significantly decreased by hesperidin. In vitro, HES suppressed the expression of IL-8 on A549 cells and THP-1 cells, the expression of TNF-alpha, IL-1 beta, and IL-6 on THP-1 cells, the expression of ICAM-1 and VCAM-1 on A549 cells which effect cell adhesion function. The suppression of those molecules is controlled by NF-kappaB and AP-1, which are activated by I kappa B and MAPK pathways. HES inhibits those pathways, thereby suppressing the expression of IL-8, TNFalpha, IL-1 beta, IL-6, IL-12, ICAM-1 and VCAM-1. This study indicates that HES had a markedly immunomodulatory effect in a clinically relevant model of ARDS. Nevertheless, further investigations are required to determine the potential clinical usefulness of HES in the adjunctive therapy of ARDS.

Analysis of signal transduction pathways in macrophages using expression vectors with CMV promoters: a cautionary tale

The cytomegalovirus (CMV) major immediate-early promoter is a strong promoter used for both in vitro and in vivo expression of proteins in signal transduction and gene therapy studies. CMV activity is induced by external stimuli such as endotoxin from Gram-negative bacteria (LPS), TNF-alpha and phorbol esters. This inducibility poses problems when this promoter is used to drive the expression of either wild type or dominant negative mutated proteins as tools in signal transduction studies. This report draws attention to the problem associated with this widely used approach. The role of NF-kappaB and Hypoxia Inducible Factor-1alpha (HIF-1alpha) in the transcriptional regulation of Vascular Endothelial Growth Factor (VEGF) in macrophages was investigated using CMV-promoter-driven expression of either wild type or dominant negative proteins involved in these pathways. Difficulties encountered while interpreting the data due to the inducibility of the CMV promoter by LPS are highlighted in this report and provide a cautionary note for the evaluation of data acquired using this approach.

Gene therapy works in animal models of rheumatoid arthritis...so what!

Rheumatoid arthritis (RA) is a systemic disease with polyarticular manifestation of chronic inflammation in the knees and small joints of hand and feet. The current systemic anti-tumor necrosis factor (TNF)-alpha therapies with biologics ameliorate disease in 60% to 70% of RA patients. However, biologics must be given systemically in relatively high dosages to achieve constant therapeutic levels in the joints, and side effects have been reported. To this end, local gene delivery can provide an alternative approach to achieve high, long-term expression of biologics, optimizing the therapeutic efficacy and minimizing systemic exposure. Evidence from animal models convincingly supports the application of local gene therapy in rheumatoid arthritis, but preclinical studies remain necessary to evaluate the merge of cell-specific targeting, viral vector development, and disease-regulated transgene expression to optimize efficacy and safety.

Protective and anti-inflammatory effect of a traditional Chinese medicine, Xia-Bai-San, by modulating lung local cytokine in a murine model of acute lung injury

We investigated the effects of Xia-Bai-San (XBS) on acute lung inflammation induced by LPS in vivo. Mice were challenged with intratracheal lipopolysaccharide (100 microg) 30 min before administering XBS (1 mg/kg oral administration). Bronchoalveolar lavage fluid (BALF) was obtained after 4 and 24 h to measure proinflammatory cytokine (TNF-alpha, IL-1beta, IL-6), anti-inflammatory cytokines (IL-10), chemokines (KC, MCP-1 and MIP-2), total cell counts, nitric oxide production, and proteins. The results indicated that XBS down-regulated the LPS-induced expression of TNF-alpha, IL-1beta, IL-6, KC, MIP-2, and MCP-1. Furthermore, it also enhanced the production of IL-10, which had increased 24 h after LPS challenge. In addition, total leukocyte counts, nitric oxide production, iNOS expression, and BALF's proteins had significantly decreased 24 h after LPS challenge. XBS was also believes to have reduced the acute inflammation by attenuating the activation of NF-kappaB. In conclusion, XBS seem to suppress lipopolysaccharide-induced lung inflammation by stimulating the production of anti-inflammatory cytokines in lung. These results suggest that XBS could be a useful adjunct in the treatment of acute respiratory distress syndrome.

Challenges and strategies: the immune responses in gene therapy

The host immune responses, including T lymphocytes mediated immune response and humoral immune responses are the important parts of the challenges in gene therapy. There are some potential immunostimulants in gene delivery systems, such as viral and non-viral vectors. Viral gene products, transgene products, viral proteins derived from viral particles required by dead-end infection, and CpG DNA in plasmid may play important roles in inducing the host immune responses when foreign genes are transferred into the targeted tissues. The immune responses should lead to many problems in gene therapy: transient expression of therapeutic gene, non-efficient re-administration of the same vectors, and severe side-effects in clinical trials. Although RNAi may act as gene therapeutic agent for suppression of specific gene expression, little attention has been given to the potential non-specific effects that might be induced. It was reported that small interfering RNAs (siRNAs) can induce the host interferon response following transfected to mammalian cells. Facing these challenges, a number of studies have been focused on taking measures to solve them, such as immunosuppression, selection of different administration routes and dose of the vectors, using the tissue-specific promoters and modifying the vectors.

Gene therapy in animal models of rheumatoid arthritis: are we ready for the patients?

Rheumatoid arthritis (RA) is a chronic inflammatory disease of the synovial joints, with progressive destruction of cartilage and bone. Anti-tumour necrosis factor-α therapies (e.g. soluble tumour necrosis factor receptors) ameliorate disease in 60–70% of patients with RA. However, the need for repeated systemic administration of relatively high doses in order to achieve constant therapeutic levels in the joints, and the reported side effects are downsides to this systemic approach. Several gene therapeutic approaches have been developed to ameliorate disease in animal models of arthritis either by restoring the cytokine balance or by genetic synovectomy. In this review we summarize strategies to improve transduction of synovial cells, to achieve stable transgene expression using integrating viruses such as adeno-associated viruses, and to achieve transcriptionally regulated expression so that drug release can meet the variable demands imposed by the intermittent course of RA. Evidence from animal models convincingly supports the application of gene therapy in RA, and the feasibility of gene therapy was recently demonstrated in phase I clinical trials.

C3-Tat/HIV-regulated intraarticular human interleukin-1 receptor antagonist gene therapy results in efficient inhibition of collagen-induced arthritis superior to cytomegalovirus-regulated expression of the same transgene

OBJECTIVE

To achieve disease-inducible expression of recombinant antiinflammatory proteins in order to allow autoregulation of drug dose by natural homeostatic mechanisms.

METHODS

We compared the inducible 2-component expression system (C3-human immunodeficiency virus/transactivator of transcription [C3-Tat/HIV]) with the constitutive cytomegalovirus (CMV) promoter in the polyarticular collagen-induced arthritis (CIA) model in mice. DBA/1 mice were immunized with bovine type II collagen and were given boosters on day 21. On day 22, mice were injected intraarticularly with the adenoviral vectors AdCMVLuc, AdCMVhIL-1Ra, AdC3-Tat/HIV-Luc, or AdC3-Tat/HIV-hIL-1Ra. The injected knee joints and hind paws were then scored for signs of arthritis, and knee joint histology was compared.

RESULTS

The CMV-driven interleukin-1 receptor antagonist (IL-1Ra) expression resulted in a high constitutive expression and amelioration of CIA. C3-Tat/HIV-driven IL-1Ra expression could be detected only on days 24, 29, and 35. Fourteen days after injection of the vectors, CIA was significantly better inhibited by the C3-Tat/HIV-driven IL-1Ra expression compared with the CMV-driven IL-1Ra expression. Moreover, prevention of CIA in the knee joints also prevented CIA in the untreated hind paws.

CONCLUSION

Our data demonstrate for the first time the feasibility of an inducible expression system for local production of IL-1Ra for treatment of arthritis in the CIA model.

Endogenous regulation of a therapeutic transgene restores homeostasis in arthritic joints

The treatment of chronic inflammatory diseases is complicated by their unpredictable, relapsing clinical course. Here, we describe a new strategy in which an inflammation-regulated therapeutic transgene is introduced into the joints to prevent recurrence of arthritis. To this end, we designed a recombinant adenoviral vector containing a two-component, inflammation-inducible promoter controlling the expression of human IL-10 (hIL-10) cDNA. When tested in vitro, this system had a low-level basal activity and was activated four to five orders of magnitude by various inflammatory stimuli, including TNF-alpha, IL-1 beta, IL-6, and LPS. When introduced in joints of rats with recurrent streptococcal cell wall-induced arthritis, the IL-10 transgene was induced in parallel with disease recurrence and effectively prevented the influx of inflammatory cells and the associated swelling of the joints. Levels of inflammation-inducible hIL-10 protein within the joints correlated closely with the severity of recurrence. An endogenously regulated therapeutic transgene can thus establish negative feedback and restore homeostasis in vivo while minimizing host exposure to the recombinant drug.

Induction of the cytokine signal regulator SOCS3/CIS3 as a therapeutic strategy for treating inflammatory arthritis

Immune and inflammatory systems are controlled by multiple cytokines, including ILs and INFs. These cytokines exert their biological functions through Janus tyrosine kinases and STAT transcription factors. One such cytokine, IL-6, has been proposed to contribute to the development of rheumatoid arthritis (RA). We found that STAT3 was strongly tyrosine phosphorylated in synovial tissue of RA patients, but not those with osteoarthritis. Blockade of the IL-6-gp130-JAK-STAT3-signaling pathway might therefore be beneficial in the treatment of RA. We show here that the mRNA for the endogenous cytokine signaling repressor CIS3/SOCS3 is abundantly expressed in RA patients. To determine whether CIS3 is effective in treating experimental arthritis, a recombinant adenovirus carrying the CIS3 cDNA was injected periarticularly into the ankle joints of mice with antigen-induced arthritis or collagen-induced arthritis (CIA). Periarticular injection of CIS3 adenovirus drastically reduced the severity of arthritis and joint swelling compared with control groups. CIS3 was more effective than a dominant-negative form of STAT3 in the CIA model. Thus, induction of CIS3 could represent a new approach for effective treatment of RA.

Promoter strength in adenovirus transducing vectors: down-regulation of the adenovirus E1A promoter in 293 cells facilitates vector construction

Most adenovirus transducing vectors have the cytomegalovirus major immediate-early (CMV) or the Rous sarcoma virus long terminal repeat (RSV) promoter driving expression of the transgene. Both of these promoters are highly active in transfection and transduction assays in 293 cells, in which transducing vectors are constructed and grown, and in HeLa cells. The CMV promoter exhibits rapid activation while the RSV promoter exhibits a lag prior to the onset of viral DNA replication in transduction assays. While the use of very strong promoters facilitates expression of the transgene, high-level expression of certain gene products hinders virus construction and growth. For such genes, the use of the adenovirus type 5 E1A promoter offers advantages. The E1A promoter exhibits modest activity in HeLa cells after transfection or transduction, but very little activity in 293 cells, suggesting that the E1A promoter would permit construction and growth of vectors encoding deleterious gene products that could not be constructed with the CMV and RSV promoters. This idea was tested through attempts to construct viruses encoding the immunoglobulin loop 6 and transmembrane regions of the prostaglandin F2alpha receptor regulatory protein (FPRP), a product that inhibits adenovirus vector construction for reasons that are not clear. Only the E1A promoter permitted construction and growth of the transducing vector encoding the fragment of FPRP.

Regulation of adenovirus-mediated elafin transgene expression by bacterial lipopolysaccharide

Lipopolysaccharide (LPS) is a mediator of inflammatory lung injury. Selective augmentation of host defense molecules such as elafin (an elastase inhibitor with antimicrobial activity) at the onset of pulmonary inflammation is an attractive potential therapeutic strategy. The aim of this study was to determine whether elafin expression could be induced by LPS administered after transfection with adenovirus (Ad) encoding human elafin downstream of the murine cytomegalovirus (CMV) promoter (known to be potentially responsive to LPS). In addition, we aimed to determine the effect of local elafin augmentation on neutrophil migration to the lung. LPS significantly up-regulated elafin expression from pulmonary epithelial cells transfected with Ad-elafin in vitro. In murine airways expression of human elafin was achieved using doses low enough (3 x 10(7) plaque forming units) to circumvent overt vector-induced inflammation. LPS significantly up-regulated human elafin secretion in murine airways treated with Ad-elafin [117 ng/ml in bronchoalveolar lavage fluid (BALF) after LPS administration, 5.9 ng/ml after PBS, p < 0.01)]. Over-expression of elafin significantly augmented LPS-mediated neutrophil migration into the airways in vivo (1.30 x 10(6) neutrophils in BALF after Ad-elafin/LPS treatment, 0.54 x 10(6) after Ad-lacZ/LPS (p < 0.05), 0.63 x 10(6) after PBS/LPS (p < 0.05)) and significantly enhanced human neutrophil migration in vitro. These data suggest novel functions for elafin in neutrophil migration, and that judicious selection of promoters may allow single, low-dose adenoviral administration to effect inflammation-specific expression of potentially therapeutic transgenes.

Gene therapy to prevent organophosphate intoxication

The specific hydrolytic activity of PON1 paraoxonase/arylesterase enzymes in liver and blood provides a natural barrier against the entry of organophosphate toxins into the central and peripheral nervous systems. Inherited differences in PON1 enzyme concentrations may determine levels of susceptibility to organophosphate injury in humans. To test whether boosting serum levels of PON1 enzymes by gene therapy might provide increased protection, we compared the degree of inactivation of whole brain acetylcholinesterase of mice exposed to chlorpyrifos 4 days after intravenous injection of recombinant adenoviruses containing PON1-LQ or PON1-LR genes or no PON1 gene. Both recombinant viruses containing PON1 genes boosted serum arylesterase concentrations by approximately 60% and significantly prevented the inactivation of brain acetylcholinesterase. Some mice were completely protected. These findings indicate that boosting serum levels of PON1 enzymes by a gene delivery vector raises the threshold for organophosphate toxicity by hydrolytic destruction before the chemical can enter the brain.

In vitro evaluation of an enhanced human serum amyloid A (SAA2) promoter-regulated soluble TNF receptor fusion protein for anti-inflammatory gene therapy

Tumour necrosis factor (TNF)-alpha contributes to the pathogenesis of many inflammatory diseases. Recombinant soluble TNF receptor fusion proteins (sTNFR:Ig) are potent TNF antagonists, both in vitro and in vivo. The concentration of serum amyloid A (SAA) increases by up to 1000-fold during inflammation, largely owing to cytokine-driven transcriptional upregulation. A reporter plasmid, comprising the proximal 0.7 kb of the human SAA2 promoter fused to a luciferase gene, was used in transient transfection experiments in human HepG2 hepatoma cells to assess the quantitative and qualitative TNF antagonist properties of a construct in which sTNFR:Ig synthesis is under the control of a chimera of the SAA2 promoter and a tat/HIV element. The SAA2-tat/HIV-sTNFR:Ig construct retained the fine-tuned cytokine responsiveness of the SAA2 promoter, while exhibiting the quantitatively enhanced level of protein expression conferred by the tat/HIV element. It produced a biologically significant TNF inhibition that was at least as strong as that achieved using a CMV promoter-driven sTNFR:Ig construct. There was a dose- and time-dependent relationship between the pro-inflammatory cytokine used, and the generation of TNF antagonist activity by SAA2-tat/HIV-sTNFR:Ig. Although sTNFR:Ig protein can be induced by either TNF-alpha or interleukin (IL)-1beta, its antagonist activity is limited to the former cytokine. The SAA2-tat/HIV-sTNFR:Ig construct, and derivatives thereof, may therefore be ideally suited to gene therapy applications that require the local production of potent and specific immune modifiers only when there is active pathology. It may consequently be of particular use in the future treatment of diseases such as rheumatoid arthritis.

What we learn from arthritis models to benefit arthritis patients

Chronic arthritis is characterized by persistent joint inflammation and concomitant joint destruction. Animal models have been of great value in understanding potential pathogenetic pathways and studying therapeutic principles. The first models were based on T cell-driven pathways and taught us that arthritis can be induced by a variety of stimuli. This suggests that the involvement of a single (auto)antigen in rheumatoid arthritis is unlikely and suggests that the regulation of arthritis can best be approached via bystander suppression. Insight into the pivotal role of TNF alpha and IL-1 has emerged from studies employing a range of common and also novel transgenic models. Combination treatment with both TNF and IL-1 blockers is warranted to control both joint inflammation and joint destruction. Novel approaches with viral gene constructs of cytokines and cytokine inhibitors teach us that efficient gene therapy is a possibility for small joints.

Exogenous control of cardiac gene therapy: evidence of regulated myocardial transgene expression after adenovirus and adeno-associated virus transfer of expression cassettes containing corticosteroid response element promoters

OBJECTIVE

Because of the relative inaccessibility of the heart for repeated gene therapy, it would be useful to regulate the expression of transgenes delivered in a single dose of a gene therapy vector. Incorporation into the vector of a regulatable promoter that is responsive to pharmacologic agents that are widely used and well tolerated in clinical practice represents such a control strategy.

METHODS

A replication-deficient adenovirus or an adeno-associated virus containing a chimeric promoter composed of 5 glucocorticoid response elements and the murine thrombopoietin complementary DNA (AdGRE.mTPO or AAVGRE.mTPO) was administered to the hearts of Sprague-Dawley rats. Platelet levels were evaluated as a reporter of transgene activity with or without dexamethasone. For comparison, rats received a control adenovirus vector, AdCMV.mTPO or AdCMV.Null, and the control adeno-associated virus vector AAVCMV.luc, which encodes for the firefly luciferase (luc) gene.

RESULTS

Platelet elevation in the AdGRE.mTPO group peaked 4 days after dexamethasone administration, with a return to baseline 1 week after the initial corticosteroid dose. Subsequent dexamethasone administration at 2 and 4 weeks resulted in similar but progressively decreased responses. The AAVGRE.mTPO group had 5 peak platelet levels to a minimum of 2.2-fold with respect to baseline without diminution with subsequent dexamethasone administrations out to 169 days. In contrast, the AdCMV.Null and AAVCMV.luc groups demonstrated no increase in platelet counts and the AdCMV.mTPO group demonstrated a slow rise to a single peak platelet count independent of dexamethasone administration.

CONCLUSION

It may be possible to control on demand the expression of a gene transferred to the heart. This strategy should be useful in cardiac gene therapy.

Percutaneous adenoviral gene transfer into porcine coronary arteries: is catheter-based gene delivery adapted to coronary circulation?

Recombinant adenoviral (Ad) vectors represent an efficient gene transfer system for targeting the cardiovascular system. Phenotypic modulation of coronary vascular cells in vivo is, however, critically dependent on the efficacy of local delivery devices. Four local drug delivery catheters were tested for intracoronary gene transfer efficiency: the Infiltrator (INF, n = 10), the Crescendo (CRE, n = 10), the Infusasleeve (SLE, n = 8), and the Remedy balloon (channel balloon [CHA], n = 8). After balloon injury of the LAD, Ad vector containing the firefly luciferase cDNA (AdCMVluc, 1.5 x 10(10) plaque-forming units) was administered at the site of injury. On day 4, tissue samples from different regions in the heart and from the liver were assayed for luciferase activity to evaluate local and systemic gene transfer. INF, CRE, and SLE catheters showed higher transduction levels of the target LAD segment than did the CHA catheter (median luciferase activity = 4.2 x 10(6), 11 x 10(6), and 1.3 x 10(6) light units [LU]/vessel versus 0.09 x 10(6) LU/vessel, respectively, p < 0.05). Luciferase activity was occasionally observed in nontarget tissues (right and left ventricular free wall, distal LAD, and liver) and was not significantly different between groups. The viral circulatory half-life was similar for the four groups (<1 min). Gene transfer efficiency was positively correlated with the degree of injury for the intralumenal catheters (CRE, SLE, and CHA) but was independent of the vessel wall injury for the intramural INF. Local drug delivery catheters enable efficient vascular gene transfer in balloon-injured coronary arteries, a prerequisite for further development of intracoronary gene therapy for restenosis.

Adenovirus vector-mediated perforin expression driven by a glucocorticoid-inducible promoter inhibits tumor growth in vivo

To evaluate the concept that in vivo transfer of perforin complementary DNA (cDNA) will suppress tumor growth, we constructed an adenovirus vector (AdGRE.PFP) carrying perforin cDNA driven by the glucocorticoid response element (GRE) promoter. We infected A549 lung carcinoma cells with this vector in vitro and in vivo, and evaluated cell growth over time. In the presence of dexamethasone, in vitro infection of A549 cells with the AdGRE.PFP vector yielded perforin messenger RNA (mRNA) transcripts and effectively suppressed A549 cell growth. In accord with these in vitro observations, administration of dexamethasone following direct injection of AdGRE. PFP into established subcutaneous A549 tumors in nude mice resulted in a marked reduction in tumor growth as compared with AdGRE.PFP infection without dexamethasone or with dexamethasone alone. These observations suggest that regulable, adenovirus-mediated gene expression of perforin cDNA may have potential as a strategy for local control of tumor cell growth.

Physiologically responsive gene therapy

The goal of physiologically responsive gene therapy is to allow a host's endogenous regulatory mechanisms to control the production of therapeutic proteins (effectors). Ideally, effector production would be switched on in response to specific signals, stay within therapeutic limits and be switched off when no longer needed. In this way, the unwanted consequences of constitutive, high-level effector expression could be avoided. While recent studies have shown that transgenes can be regulated within animal hosts, they have also highlighted significant problems that require much further research.

Intermittent, Repetitive Corticosteroid-Induced Upregulation of Platelet Levels After Adenovirus-Mediated Transfer to the Liver of a Chimeric Glucocorticoid-Responsive Promoter Controlling the Thrombopoietin cDNA

For many in vivo gene therapy clinical applications, it is desirable to control the expression of the transferred transgene using pharmacologic agents. To evaluate the feasibility of accomplishing this using corticosteroids, pharmacologic agents widely used in clinical medicine, we constructed replication deficient adenoviral (Ad) vectors containing an expression cassette with a chimeric promoter comprised of five glucocorticoid response elements (GRE) and the chloramphenicol acetyltransferase reporter gene (AdGRE.CAT) or the murine thrombopoietin cDNA (AdGRE.mTPO). In vitro studies showed the vectors functioned as expected, with marked glucocorticoid-induced upregulation of the CAT or mTPO transgenes. To evaluate the inducibility of the GRE promoter in vivo, the AdGRE.CAT vector was administered intravenously to C57B1/6 mice, and CAT activity was quantified in liver before and after intraperitoneal administration of dexamethasone. The GRE promoter activity was dependent on the dexamethasone dose, with a 100-fold increase in CAT expression with 50 μg dexamethasone, similar to the levels observed in vivo with the Rous sarcoma virus long terminal repeat constitutive promoter. After dexamethasone administration, maximum CAT activity was observed at day 2, with a slow decline to baseline levels by 2 weeks. Based on these observations, we hypothesized that a single administration of an Ad vector-mediated transfer of the chimeric GRE inducible promoter driving the mTPO cDNA would enable repetitive administration of corticosteroids to repetitively upregulate platelet levels for 1 to 2 weeks. The data show that this occurs, with dexamethasone administration every 3 weeks associated with 1-week elevations (at each 3-week interval) of serum mTPO levels, megakaryocyte numbers in bone marrow, and platelet levels fourfold to sixfold over baseline. Thus, with the appropriate promoter, it is possible to use a commonly used pharmacologic agent to upregulate the expression of a newly transferred gene on demand.

© 1998 by The American Society of Hematology.

Intermittent, Repetitive Corticosteroid-Induced Upregulation of Platelet Levels After Adenovirus-Mediated Transfer to the Liver of a Chimeric Glucocorticoid-Responsive Promoter Controlling the Thrombopoietin cDNA

For many in vivo gene therapy clinical applications, it is desirable to control the expression of the transferred transgene using pharmacologic agents. To evaluate the feasibility of accomplishing this using corticosteroids, pharmacologic agents widely used in clinical medicine, we constructed replication deficient adenoviral (Ad) vectors containing an expression cassette with a chimeric promoter comprised of five glucocorticoid response elements (GRE) and the chloramphenicol acetyltransferase reporter gene (AdGRE.CAT) or the murine thrombopoietin cDNA (AdGRE.mTPO). In vitro studies showed the vectors functioned as expected, with marked glucocorticoid-induced upregulation of the CAT or mTPO transgenes. To evaluate the inducibility of the GRE promoter in vivo, the AdGRE.CAT vector was administered intravenously to C57B1/6 mice, and CAT activity was quantified in liver before and after intraperitoneal administration of dexamethasone. The GRE promoter activity was dependent on the dexamethasone dose, with a 100-fold increase in CAT expression with 50 μg dexamethasone, similar to the levels observed in vivo with the Rous sarcoma virus long terminal repeat constitutive promoter. After dexamethasone administration, maximum CAT activity was observed at day 2, with a slow decline to baseline levels by 2 weeks. Based on these observations, we hypothesized that a single administration of an Ad vector-mediated transfer of the chimeric GRE inducible promoter driving the mTPO cDNA would enable repetitive administration of corticosteroids to repetitively upregulate platelet levels for 1 to 2 weeks. The data show that this occurs, with dexamethasone administration every 3 weeks associated with 1-week elevations (at each 3-week interval) of serum mTPO levels, megakaryocyte numbers in bone marrow, and platelet levels fourfold to sixfold over baseline. Thus, with the appropriate promoter, it is possible to use a commonly used pharmacologic agent to upregulate the expression of a newly transferred gene on demand.

© 1998 by The American Society of Hematology.

A two-component expression system that responds to inflammatory stimuli in vivo

A therapeutic dilemma often complicates the management of inflammatory diseases; the benefits gained from reducing inflammation must be balanced against the potentially harmful consequences of chronic immunosuppression. Gene therapy might address this dilemma by producing anti-inflammatory proteins in response to a patient's endogenous signals, so that recombinant drug production is linked to the intensity and duration of the inflammatory condition. To test this, we have developed inflammation-inducible systems for regulating recombinant protein production in vivo. We describe a two-component expression construct in which (1) the murine complement factor 3 (C3) promoter regulates production of the human immunodeficiency virus (HIV) transactivator of transcription (Tat), and (2) the Tat protein then stimulates protein expression from genes inserted downstream of the the HIV promoter. When incorporated into a nonreplicating adenovirus (Ad.C3-tat/HIV-luc) and studied in a murine model, the construct produces large amounts of recombinant protein in vivo in response to two different inflammatory stimuli.

Creation of an In vivo cytosensor using engineered mesangial cells. Automatic sensing of glomerular inflammation controls transgene activity

Automatic control over exogenous gene expression in response to the activity of disease is a crucial hurdle for gene transfer-based therapies. Towards achieving this goal, we created a "cytosensor" that perceives local inflammatory states and subsequently regulates foreign gene expression. alpha-Smooth muscle actin is known to be expressed in glomerular mesangial cells exclusively in pathologic situations. CArG box element, the crucial regulatory sequence of the alpha-smooth muscle actin promoter, was used as a sensor for glomerular inflammation. Rat mesangial cells were stably transfected with an expression plasmid that introduces a beta-galactosidase gene under the control of CArG box elements. In vitro, the established cells expressed beta-galactosidase exclusively after stimulation with serum. To examine whether the cells are able to automatically control transgene activity in vivo, serum-stimulated or unstimulated cells were transferred into normal rat glomeruli or glomeruli subjected to anti-Thy 1 glomerulonephritis. When stimulated cells were transferred into the normal glomeruli, beta-galactosidase expression was switched off in vivo within 3 d. In contrast, when unstimulated cells were transferred into the nephritic glomeruli, transgene expression was substantially induced. These data indicate the feasibility of using the CArG box element as a molecular sensor for glomerular injury. In the context of advanced forms of gene therapy, this approach provides a novel concept for automatic regulation of local transgene expression where the transgene is required to be activated during inflammation and deactivated when the inflammation has subsided.

Adenovirus-Mediated Transfer of Tissue-Type Plasminogen Activator Augments Thrombolysis in Tissue-Type Plasminogen Activator–Deficient and Plasminogen Activator Inhibitor-1–Overexpressing Mice

Impaired fibrinolysis, resulting from increased plasminogen activator inhibitor-1 (PAI-1) or reduced tissue-type plasminogen activator (t-PA) plasma levels, may predispose the individual to subacute thrombosis in sepsis and inflammation. The objective of these studies was to show that adenovirus-mediated gene transfer could increase systemic plasma t-PA levels and thrombolytic capacity in animal model systems. Recombinant adenovirus vectors were constructed that express either human wild type or PAI-1–resistant t-PA from the cytomegalovirus (CMV) promoter. Both t-PA-deficient (t-PA−/−) and PAI-1–overexpressing transgenic mice were infected by intravenous injection of these viruses. Intravenous injection of recombinant adenovirus resulted in liver gene transfer, t-PA synthesis, and secretion into the plasma. Virus dose, human t-PA antigen, and activity concentrations in plasma and extent of lysis of a 125I-fibrin–labeled pulmonary embolism were all closely correlated. Plasma t-PA antigen and activity were increased approximately 1,000-fold above normal levels. Clot lysis was significantly increased in mice injected with a t-PA–expressing virus, but not in mice injected with saline or an irrelevant adenovirus. Comparable levels of enzyme activity and clot lysis were obtained with wild type and inhibitor-resistant t-PA viruses. Adenovirus-mediated t-PA gene transfer was found to augment clot lysis as early as 4 hours after infection, but expression levels subsided within 7 days. Adenovirus-mediated transfer of a t-PA gene can effectively increase plasma fibrinolytic activity and either restore (in t-PA–deficient mice) or augment (in PAI-1–overexpressing mice) the thrombolytic capacity in simple animal models of defective fibrinolysis.

Adenovirus-Mediated Transfer of Tissue-Type Plasminogen Activator Augments Thrombolysis in Tissue-Type Plasminogen Activator–Deficient and Plasminogen Activator Inhibitor-1–Overexpressing Mice

Impaired fibrinolysis, resulting from increased plasminogen activator inhibitor-1 (PAI-1) or reduced tissue-type plasminogen activator (t-PA) plasma levels, may predispose the individual to subacute thrombosis in sepsis and inflammation. The objective of these studies was to show that adenovirus-mediated gene transfer could increase systemic plasma t-PA levels and thrombolytic capacity in animal model systems. Recombinant adenovirus vectors were constructed that express either human wild type or PAI-1–resistant t-PA from the cytomegalovirus (CMV) promoter. Both t-PA-deficient (t-PA−/−) and PAI-1–overexpressing transgenic mice were infected by intravenous injection of these viruses. Intravenous injection of recombinant adenovirus resulted in liver gene transfer, t-PA synthesis, and secretion into the plasma. Virus dose, human t-PA antigen, and activity concentrations in plasma and extent of lysis of a 125I-fibrin–labeled pulmonary embolism were all closely correlated. Plasma t-PA antigen and activity were increased approximately 1,000-fold above normal levels. Clot lysis was significantly increased in mice injected with a t-PA–expressing virus, but not in mice injected with saline or an irrelevant adenovirus. Comparable levels of enzyme activity and clot lysis were obtained with wild type and inhibitor-resistant t-PA viruses. Adenovirus-mediated t-PA gene transfer was found to augment clot lysis as early as 4 hours after infection, but expression levels subsided within 7 days. Adenovirus-mediated transfer of a t-PA gene can effectively increase plasma fibrinolytic activity and either restore (in t-PA–deficient mice) or augment (in PAI-1–overexpressing mice) the thrombolytic capacity in simple animal models of defective fibrinolysis.

Long-term gene delivery into the livers of immunocompetent mice with E1/E4-defective adenoviruses

We have compared the in vitro and in vivo behaviors of a set of isogenic E1- and E1/E4-defective adenoviruses expressing the lacZ gene of Escherichia coli from the Rous sarcoma virus long terminal repeat. Infection of tumor-derived established cell lines of human origin with the doubly defective adenoviruses resulted in (i) a lower replication of the viral backbone that correlated with reduced levels of E2A-specific RNA and protein, (ii) a significant shutoff of late gene and protein expression, and (iii) no apparent virus-induced cytotoxicity. Independently of the extent of the deletion, the additional inactivation of E4 from the viral backbone therefore drastically disabled the virus in vitro, with no apparent effect on transgene expression. A lacZ-transgenic model was used to compare the different recombinant adenoviruses in the livers of C57BL/6 mice. The immune response to the virally encoded beta-galactosidase was minimal in this model, as infusion of the E1-defective adenovirus resulted in a time course of transgene expression that mimicked that in immunodeficient (nu/nu) mice, with very little inflammation and necrosis in the liver. Administration of a doubly defective adenovirus to the transgenic animals led to long-term extrachromosomal persistence of viral DNA in the liver, with no detectable methylation of CpG dinucleotides. However, transient transgene expression was observed independently of the extent of the E4 deletion, suggesting that the choice of the promoter may be critical to maintain transgene expression from these attenuated adenovirus vectors.

Progress in transcriptionally targeted and regulatable vectors for genetic therapy

Safety is an important consideration in the development of genetic therapy protocols; for example, proteins that are therapeutic in the context of one tissue may be harmful in another. This is particularly relevant to suicide gene strategies for cancer, which require in vivo delivery of DNA and which, in general, demand that the therapeutic product be limited as far as possible to malignant cells. This has led to a requirement for "transcriptionally targeted" vectors that can restrict the expression of the therapeutic sequence to appropriate cells. Furthermore, there may be a therapeutic window for certain proteins such that levels of expression below and above certain thresholds may be ineffective or toxic, respectively. Therefore, it would also be desirable to create vectors that allow exogenous control of expression, so that levels of the therapeutic protein can be raised or lowered according to therapeutic need. In the context of transcriptional targeting, one may sometimes use cis-acting sequences to limit transgene expression to the target cell type. In genetic therapy for cancer, for example, it may be possible to identify and use transcriptional control elements that drive expression of proteins unique to, or over-expressed in, malignant cells. These controls would greatly reduce collateral expression of the transgene, and hence reduce toxicity to healthy cells. With regard to exogenous control of expression subsequent to transduction, several synthetic gene regulation systems have now been produced. In these systems, an inducer or repressor acts on a synthetic transcription factor that recognizes motifs unique to the promoter of the transgene; this allows regulated expression of the therapeutic protein without nonspecific effects on cellular promoters. It is likely that a vector will soon be produced in which tissue-restricted expression of the synthetic transcription factor is combined with regulatable transgene expression thereby allowing precise control of therapeutic protein production in specific tissues via administration of an inducing or repressing agent.

Transductional efficacy and safety of an intraperitoneally delivered adenovirus encoding an anti-erbB-2 intracellular single-chain antibody for ovarian cancer gene therapy

We have previously shown that adenoviral-mediated delivery of an anti-erbB-2 intracellular single-chain antibody (sFv) causes specific cytotoxicy in erbB-2-overexpressing ovarian carcinoma cells. Furthermore, intraperitoneal delivery of the anti-erbB-2 sFv enhances survival and reduces tumor burden in a xenograft model of human ovarian carcinoma in SCID mice. These findings have led to an RAC-approved Phase I clinical trial for patients with ovarian cancer. In this report, we show that expression of the anti-erbB-2 sFv could be readily detected in target tumor cells by in situ hybridization methodology. PCR analysis of DNA extracted from various murine tissues demonstrated that the anti-erbB-2 sFv remained localized to the peritoneum. Delivery of the sFv to the non-erbB-2-overexpressing REN mesothelial and Hep G2 hepatocellular carcinoma cell lines was not deleterious to either one, affirming the tumor specificity of this gene therapy strategy. In addition, histopathological analysis of various tissues showed that adenoviral-mediated delivery of the anti-erbB-2 sFv to immunocompetent mice with either primary exposure or previous vector challenge at different doses produced no abnormal changes when compared to untreated animals. These findings suggest that adenoviral-mediated delivery of the anti-erbB-2 sFv in a human context can be effectively assayed, is potentially free of vector-associated toxicity, and retains biologic utility based on tumor specificity.

Regulatable promoters for use in gene therapy applications: modification of the 5'-flanking region of the CFTR gene with multiple cAMP response elements to support basal, low-level gene expression that can be upregulated by exogenous agents that raise intracellular levels of cAMP

This study focuses on the design, construction, and evaluation of a chimeric promoter for gene therapy applications where it is desirable to have low-level basal expression of the newly transferred gene, which can be induced to higher levels of expression by the administration of pharmacologic agents that can be safely used locally and/or systemically in humans. To achieve this, a chimeric promoter was constructed using fragments of the 5'-flanking region of the human cystic fibrosis transmembrane conductance regulator (CFTR) gene, and multiple tandem repeats of the consensus sequence and flanking elements of the cAMP response element (CRE), promoter sequences that support increased transcription in response to elevations in intracellular cAMP levels. Preliminary studies using plasmid vectors demonstrated that: (i) the 5'-flanking sequences from the CFTR gene have low promoter activity in the human airway epithelial cell lines; (ii) chimeras using -718 bp fragment from the 5'-flanking sequence of CFTR gene as the base, with the addition of 4-10 units of a 25-bp sequence containing the CRE consensus sequence, were all inducible by a rise in intracellular cAMP, with the chimera having eight CRE repeats the most responsive; and (iii) a CF126(CRE8) chjimera, consisting of the -126 bp fragment from the 5'-flanking region of CFTR gene together with eight CRE repeats, yielded low-level basal activity but maximal upregulation by cAMP, resulting in expression of the reporter gene that was 51-58% of an RSV-LTR control. On the basis of these observations, replication-deficient adenoviral vectors containing the CF126(CRE8) chimera and the luciferase reporter gene [AdCF126(CRE8).Luc] or the Escherichia coli lacZ (beta-Gal) reporter gene [AdCF126(CRE8). beta gal] were constructed. In several human airway epithelial cell lines, the AdCF126 (CRE). Luc vector provided low basal activity, but was significantly upregulated by agents that increase cAMP levels. Intranasal administration of the beta-Gal-expressing AdCF126(CRE8) beta gal vector into C57B1/6 mice demonstrated cAMP-induced upregulation of the reporter gene in airway epithelial cells. Quantification of the inducibility of the basal promoter activity in the airway epithelium using the AdCF126(CRE8). Luc vector demonstrated an 11-fold upregulation of the basal promoter activity in the lung with the administration of a phosphodiesterase inhibitor and a cAMP analog. These observations demonstrate the feasibility of using a chimeric promoter comprised of a minimal fragment of the CFTR 5'-flanking region, together with added multiple CRE, to control genes delivered in vivo. Importantly, because there are many drugs used in humans that raise cAMP, the concept of using a cAMP-regulatable promoter may also be a useful approach to enhance the safety, efficacy, and feasibility of a variety of human gene therapy strategies.

Adenoviral-mediated delivery of herpes simplex virus thymidine kinase results in tumor reduction and prolonged survival in a SCID mouse model of human ovarian carcinoma

The herpes simplex virus thymidine kinase gene is the most widely utilized toxin for selective killing of carcinoma cells. Expression of the viral thymidine kinase gene renders cells sensitive to the toxic effects of nucleoside analogs such as ganciclovir. An advantage of this system is the "bystander effect" whereby thymidine kinase transduced tumor cells elicit a toxic effect on surrounding nontransduced tumor cells. Ovarian carcinoma appears to be an ideal candidate for gene therapy as the majority of women present with advanced stage disease, have poor prognosis for long-term survival and have the disease confined within the peritoneal cavity. Therefore the utility of an adenoviral vector to elicit an in vitro bystander effect in ovarian carcinoma cells and the therapeutic efficacy of such a system in vivo was undertaken. Immunocompetent animals were utilized to determine the maximum dose of adenovirus that could be administered without any undesirable side effects and that preimmunization had no effects on subsequent challenge. SCID mice were orthotopically transplanted with human ovarian carcinoma cells and, after establishment of tumor, given a recombinant adenovirus expressing either the herpes simplex virus thymidine kinase or the Escherichia coli beta-galactosidase gene. Half the animals from each viral group were treated with either a ganciclovir regiment (50 mg/kg daily for 14 days) or an equal volume of serum-free media. A subset of mice were killed following drug treatment and analyzed for tumor reduction. The remaining animals were followed daily for survival. The animals treated with the recombinant adenovirus expressing the herpes simplex virus thymidine kinase gene and ganciclovir had significant reduction in overall tumor burden and demonstrated statistically significant prolongation in overall survival.