Differential expression of tissue-specific promoters by gene gun

Development of Minicircle Vectors Encoding COL7A1 Gene with Human Promoters for Non-Viral Gene Therapy for Recessive Dystrophic Epidermolysis Bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a rare autosomal inherited skin disorder caused by mutations in the COL7A1 gene that encodes type VII collagen (C7). The development of an efficient gene replacement strategy for RDEB is mainly hindered by the lack of vectors able to encapsulate and transfect the large cDNA size of this gene. To address this problem, our group has opted to use polymeric-based non-viral delivery systems and minicircle DNA. With this approach, safety is improved by avoiding the usage of viruses, the absence of bacterial backbone, and the replacement of the control viral cytomegalovirus (CMV) promoter of the gene with human promoters. All the promoters showed impressive C7 expression in RDEB skin cells, with eukaryotic translation elongation factor 1 α (EF1α) promoter producing higher C7 expression levels than CMV following minicircle induction, and COL7A1 tissue-specific promoter (C7P) generating C7 levels similar to normal human epidermal keratinocytes. The improved system developed here has a high potential for use as a non-viral topical treatment to restore C7 in RDEB patients efficiently and safely, and to be adapted to other genetic conditions.

Safe and efficient novel approach for non-invasive gene electrotransfer to skin

Gene transfer into cells or tissue by application of electric pulses (i.e. gene electrotransfer (GET)) is a non-viral gene delivery method that is becoming increasingly attractive for clinical applications. In order to make GET progress to wide clinical usage its efficacy needs to be improved and the safety of the method has to be confirmed. Therefore, the aim of our study was to increase GET efficacy in skin, by optimizing electric pulse parameters and the design of electrodes. We evaluated the safety of our novel approach by assaying the thermal stress effect of GET conditions and the biodistribution of a cytokine expressing plasmid. Transfection efficacy of different pulse parameters was determined using two reporter genes encoding for the green fluorescent protein (GFP) and the tdTomato fluorescent protein, respectively. GET was performed using non-invasive contact electrodes immediately after intradermal injection of plasmid DNA into mouse skin. Fluorescence imaging of transfected skin showed that a sophistication in the pulse parameters could be selected to get greater transfection efficacy in comparison to the standard ones. Delivery of electric pulses only mildly induced expression of the heat shock protein Hsp70 in a luminescent reporting transgenic mouse model, demonstrating that there were no drastic stress effects. The plasmid was not detected in other organs and was found only at the site of treatment for a limited period of time. In conclusion, we set up a novel approach for GET combining new electric field parameters with high voltage short pulses and medium voltage long pulses using contact electrodes, to obtain a high expression of both fluorescent reporter and therapeutic genes while showing full safety in living animals.

Suppression of the CD8 T cell response by human papillomavirus type 16 E7 occurs in Langerhans cell-depleted mice

Human papillomavirus (HPV) is an epitheliotropic virus that is the primary causal agent for cervical cancer. Langerhans cells (LC) are skin antigen presenting cells that are reduced in number in HPV-infected skin. The aim of this study was to understand the immune-modulatory effects of HPV16 E7 on LC and on the CD8 T cell response to a skin-expressed antigen. To test this, HPV16 E7 was expressed in mouse skin keratinocytes with the model antigen ovalbumin (Ova). Similar to what is observed in HPV-infected human skin, LC numbers were significantly reduced in E7-expressing mouse skin. This shows that expression of the E7 protein alone is sufficient to mediate LC depletion. Expression of E7 with Ova in keratinocytes strongly suppressed the Ova-specific CD8⁺ T cell response in the skin draining lymph node. When tested in LC-ablated mice, the CD8 T cell response to skin-expressed Ova in control mice was not affected, nor was the T cell response to Ova restored in E7-expressing skin. These data indicate a role for E7 in regulation of LC homeostasis in the skin and in suppression of antigen specific CD8 T cell expansion, but suggest that these two effects occur independent of each other.

Toll-Like Receptor 9 Activation Rescues Impaired Antibody Response in Needle-free Intradermal DNA Vaccination

The delivery of plasmid DNA to the skin can target distinct subsets of dermal dendritic cells to confer a superior immune response. The needle-free immunization technology offers a reliable, safe and efficient means to administer intradermal (ID) injections. We report here that the ID injection of DNA vectors using an NF device (NF-ID) elicits a superior cell-mediated immune response, at much lesser DNA dosage, comparable in magnitude to the traditional intramuscular immunization. However, the humoral response is significantly impaired, possibly at the stage of B cell isotype switching. We found that the NF-ID administration deposits the DNA primarily on the epidermis resulting in a rapid loss of the DNA as well as the synthesized antigen due to the faster regeneration rate of the skin layers. Therefore, despite the immune-rich nature of the skin, the NF-ID immunization of DNA vectors may be limited by the impaired humoral response. Additional booster injections are required to augment the antibody response. As an alternative and a viable solution, we rescued the IgG response by coadministration of a Toll-like receptor 9 agonist, among other adjuvants examined. Our work has important implication for the optimization of the emerging needle-free technology for ID immunization.

Improved Specificity of Gene Electrotransfer to Skin Using pDNA Under the Control of Collagen Tissue-Specific Promoter

In order to ensure safe, efficient and controlled gene delivery to skin, the improvement of delivery methods together with proper design of DNA is required. Non-viral delivery methods, such as gene electrotransfer, and the design of tissue-specific promoters are promising tools to ensure the safety of gene delivery to the skin. In the scope of our study, we evaluated a novel skin-specific plasmid DNA with collagen (COL) promoter, delivered to skin cells and skin tissue by gene electrotransfer. In vitro, we determined the specificity of the COL promoter in fibroblast cells. The specific expression under the control of COL promoter was obtained for the reporter gene DsRed as well as for therapeutic gene encoding cytokine IL-12. In vivo, the plasmid with COL promoter encoding the reporter gene DsRed was efficiently transfected to mouse skin. It resulted in the notable and controlled manner, however, in lower and shorter expression, compared to that obtained with ubiquitous promoter. The concentration of the IL-12 in the skin after the in vivo transfection of plasmid with COL promoter was in the same range as after the treatment in control conditions (injection of distilled water followed by the application of electric pulses). Furthermore, this gene delivery was local, restricted to the skin, without any evident systemic shedding of IL-12. Such specific targeting of skin cells, observed with tissue-specific COL promoter, would improve the effectiveness and safety of cutaneous gene therapies and DNA vaccines.

Activation of p53 by spermine mediates induction of autophagy in HT1080 cells

The recent evidences indicate that autophagy is associated with a number of pathological processes including cancer, muscular disorder and neurodegeneration in addition to longevity. The efficacy of spermine was investigated on induction of autophagy through histone deacetylation and p53 activation in human fibrosarcoma cell line, HT1080. In this study, it was discovered that spermine increases the activity of HAT and autophagy. It was also identified that the transcriptional activation of p53 and the activation of p21 promoter by spermine are related to the induction of autophagy in reporter gene assay. Furthermore, western blot analyses demonstrated that spermine modulates the expression of proteins related to autophagy and apoptosis. The expression levels of Ac-histone H3, HDAC1, HAT1, p300 and SIRT1 were increased in HT1080 cells treated with spermine. In addition, the expression levels of protein such as acetyl-p53, p-p53, Bcl-2 and caspase-9 inducing apoptosis were increased in the presence of spermine. Moreover, the levels of Mdm2 and caspase-3 expression were reduced in the cells exposed to spermine compared to blank group. These results suggest that activation of HAT in the presence of spermine promotes the induction of autophagy in HT1080 cells through the enhanced activity of p-p53 and acetyl p53.

Translational Approaches towards Cancer Gene Therapy: Hurdles and Hopes

INTRODUCTION

Of the cancer gene therapy approaches, gene silencing, suicide/apoptosis inducing gene therapy, immunogene therapy and targeted gene therapy are deemed to sub-stantially control the biological consequences of genomic changes in cancerous cells. Thus, a large number of clinical trials have been conducted against various malignancies. In this review, we will discuss recent translational progresses of gene and cell therapy of cancer.

METHODS

Essential information on gene therapy of cancer were reviewed and discussed towards their clinical translations.

RESULTS

Gene transfer has been rigorously studied in vitro and in vivo, in which some of these gene therapy endeavours have been carried on towards translational investigations and clinical applications. About 65% of gene therapy trials are related to cancer therapy. Some of these trials have been combined with cell therapy to produce personalized medicines such as Sipuleucel-T (Provenge®, marketed by Dendreon, USA) for the treatment of asymptomatic/minimally symptomatic metastatic hormone-refractory prostate cancer.

CONCLUSION

Translational approach links two diverse boundaries of basic and clinical researches. For successful translation of geno-medicines into clinical applications, it is essential 1) to have the guidelines and standard operating procedures for development and application of the genomedicines specific to clinically relevant biomarker(s); 2) to conduct necessary animal experimental studies to show the "proof of concept" for the proposed genomedicines; 3) to perform an initial clinical investigation; and 4) to initiate extensive clinical trials to address all necessary requirements. In short, translational researches need to be refined to accelerate the geno-medicine development and clinical applications.

Visualization of plasmid delivery to keratinocytes in mouse and human epidermis

The accessibility of skin makes it an ideal target organ for nucleic acid-based therapeutics; however, effective patient-friendly delivery remains a major obstacle to clinical utility. A variety of limited and inefficient methods of delivering nucleic acids to keratinocytes have been demonstrated; further advances will require well-characterized reagents, rapid noninvasive assays of delivery, and well-developed skin model systems. Using intravital fluorescence and bioluminescence imaging and a standard set of reporter plasmids we demonstrate transfection of cells in mouse and human xenograft skin using intradermal injection and two microneedle array delivery systems. Reporter gene expression could be detected in individual keratinocytes, in real-time, in both mouse skin as well as human skin xenografts. These studies revealed that non-invasive intravital imaging can be used as a guide for developing gene delivery tools, establishing a benchmark for comparative testing of nucleic acid skin delivery technologies.

Halting angiogenesis by non-viral somatic gene therapy alleviates psoriasis and murine psoriasiform skin lesions

Dysregulated angiogenesis is a hallmark of chronic inflammatory diseases, including psoriasis, a common skin disorder that affects approximately 2% of the population. Studying both human psoriasis in 2 complementary xenotransplantation models and psoriasis-like skin lesions in transgenic mice with epidermal expression of human TGF-β1, we have demonstrated that antiangiogenic non-viral somatic gene therapy reduces the cutaneous microvasculature and alleviates chronic inflammatory skin disorders. Transient muscular expression of the recombinant disintegrin domain (RDD) of metargidin (also known as ADAM-15) by in vivo electroporation reduced cutaneous angiogenesis and vascularization in all 3 models. As demonstrated using red fluorescent protein-coupled RDD, the treatment resulted in muscular expression of the gene product and its deposition within the cutaneous hyperangiogenic connective tissue. High-resolution ultrasound revealed reduced cutaneous blood flow in vivo after electroporation with RDD but not with control plasmids. In addition, angiogenesis- and inflammation-related molecular markers, keratinocyte proliferation, epidermal thickness, and clinical disease scores were downregulated in all models. Thus, non-viral antiangiogenic gene therapy can alleviate psoriasis and may do so in other angiogenesis-related inflammatory skin disorders.

Increased interstitial pressure improves nucleic acid delivery to skin enabling a comparative analysis of constitutive promoters

Nucleic acid-based therapies hold great promise for treatment of skin disorders if delivery challenges can be overcome. To investigate one mechanism of nucleic acid delivery to keratinocytes, a fixed mass of expression plasmid was intradermally injected into mouse footpads in different volumes, and reporter expression was monitored by intravital imaging or skin sectioning. Reporter gene expression increased with higher delivery volumes, suggesting that pressure drives nucleic acid uptake into cells after intradermal injections similar to previously published studies for muscle and liver. For spatiotemporal analysis of reporter gene expression, a dual-axis confocal (DAC) fluorescence microscope was used for intravital imaging following intradermal injections. Individual keratinocytes expressing hMGFP were readily visualized in vivo and initially appeared to preferentially express in the stratum granulosum and subsequently migrate to the stratum corneum over time. Fluorescence microscopy of frozen skin sections confirmed the patterns observed by intravital imaging. Intravital imaging with the DAC microscope is a noninvasive method for probing spatiotemporal control of gene expression and should facilitate development and testing of new nucleic acid delivery technologies.

From Plasmids to Protection: A Review of DNA Vaccines Against Infectious Diseases

The field of DNA vaccine development began over 16 years ago with the observation that plasmid DNA could be injected into and expressed in vivo and drive adaptive immune responses. Since then, there has been great interest in developing this technology to create a new generation of vaccines with the ability to elicit both humoral and cellular immune responses from an inherently innocuous injection. However, DNA vaccines have yet to proceed past phase I/II clinical trials in humans--primarily due to a desire to induce more potent immune responses. This review will examine how DNA vaccines function to induce an immune response and how this information might be useful in future vaccine design.

Anti-inflammatory effect of Ishige okamurae ethanolic extract via inhibition of NF-kappaB transcription factor in RAW 264.7 cells

Nowadays, much attention has been paid to the development of anti-inflammatory agents from marine natural resources. As a result of screening anti-inflammatory agents from marine algae using immunoassay, we found for the first time that ethanolic extract of Ishige okamurae (IO) classified into brown algae was effective in inhibiting the production of inflammatory mediators, such as tumor necrosis factor-alpha, interleukin-1beta, interleukin-6 and prostaglandin E(2), in RAW264.7 cells stimulated by lipopolysaccharide, compared with dexamethasone and aspirin used as positive control in this study. Moreover, transcriptional activation of NF-kappaB transcription factor that regulates the expression of these inflammatory mediators was also examined using reporter gene assay and western blot analysis. It was observed that IO extract exerted anti-inflammatory effect via inactivation of NF-kappaB transcription factor in macrophages. In addition, the expression and activity of matrix metalloproteinase-2 and 9 that play an important role in chronic inflammation were decreased in dose-dependent manner in the presence of IO extract in HT1080 cells. The above results suggest that IO extract can inhibit inflammation through inactivation of NF-kappaB transcription factor in macrophage.

Development of CRTEIL and CETRIZ, Cre-loxP-based systems, which allow change of expression of red to green or green to red fluorescence upon transfection with a cre-expression vector

We developed Cre-loxP-based systems, termed CRTEIL and CETRIZ, which allow gene switching in a noninvasive manner. Single transfection with pCRTEIL resulted in predominant expression of red fluorescence. Cotransfection with pCRTEIL and Cre-expression plasmid (pCAG/NCre) caused switching from red to green fluorescence. Similarly, cotransfection with pCETRIZ and pCAG/NCre resulted in change of green to red fluorescence. These noninvasive systems will be useful in cell lineage analysis, since descendants of cells exhibiting newly activated gene expression can be continuously monitored in noninvasive fashion.

Laurencia okamurai extract containing laurinterol induces apoptosis in melanoma cells

Laurinterol is a marine sesquiterpene that has been known to have antimicrobial activity. The purpose of this study is to investigate the effect of Laurencia okamurai extract containing laurinterol (LOEL) on induction of apoptosis in melanoma cells (B16F1). Anticancer activity of LOEL against melanoma cells was shown in a dose-dependent manner by the 1-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. It was for the first time found that LOEL exhibited an excellent effect on the induction of apoptosis as determined by DNA fragmentation, terminal deoxynucleotidyl transferase-mediated dUTP in situ nick-end labeling assay, cell cycle analysis, and measurement of activities of several caspases in melanoma cells. It was also demonstrated that transcriptional activation of p53, a tumor suppressor gene, and activation of p21 promoter by LOEL were involved in the induction of apoptosis by reporter gene assay. In particular, western blot analysis confirmed that LOEL above 5 microg/mL significantly increased the expression level of phospho-p53, the active form. These results indicate that LOEL can induce apoptosis through a p53-dependent pathway in melanoma cells.

Plasmid engineering for controlled and sustained gene expression for nonviral gene therapy

Gene therapy requires the introduction of genetic material in diseased cells with the aim of treating or ultimately curing a disease. Since the start of gene therapy clinical trials in 1990, gene therapy has proven to be possible, but studies to date have highlighted the difficulty of achieving efficient, specific, and long-term transgene expression. Efforts to improve gene therapy strategies over the past years were mainly aimed at solving the problem of delivery, without paying much attention to the optimization of the expression cassette. With the current understanding of the eukaryotic transcription machinery and advanced molecular biology techniques at our disposition, it has now become possible to create custom-made transgene expression cassettes optimized for gene therapy applications. In this review, we will discuss several strategies that have been explored to improve the level and duration of transgene expression, to increase control over expression, or to restrict transgene expression to specific cell types or tissues. Although still in its infancy, such strategies will eventually lead to improvement of nonviral gene therapy and expansion of the range of possible therapeutic applications.

Insufficient APC capacities of dendritic cells in gene gun-mediated DNA vaccination

Gene gun-mediated DNA immunization is a powerful mode of vaccination against infectious diseases and tumors. Many studies have identified dendritic cells (DC) as the central players in inducing immunity upon biolistic DNA vaccination; however, none of these studies directly quantify DC-mediated responses in comparison with immunity triggered by all Ag- and MHC-expressing cells. In this study we use two different approaches to decipher the relative role of DC vs other cell types in gene gun-induced immunity. First, we directly compared the immunization efficacy of different DNA constructs, which allow Ag expression ubiquitously (CMV promoter) or specifically in DC (CD11c promoter) and would encode either for soluble or membrane bound forms of Ag. Second, we immunized transgenic mice in which only DC can present MHC-restricted Ag, and directly compared the magnitudes of CTL activation with those obtained in wild-type mice. Surprisingly, our combined data suggest that, although DC-specific Ag expression is sufficient to induce humoral responses, DC alone cannot trigger optimal CD4 and CD8 T cell responses upon gene gun vaccination. Therefore, we conclude that DC alone are insufficient to mediate optimal induction of T cell immunity upon gene gun DNA vaccination and that broad Ag expression rather than DC-restricted approaches are necessary for induction of complete immune responses.

Tf-lipoplex-mediated NGF gene transfer to the CNS: neuronal protection and recovery in an excitotoxic model of brain injury

The development of efficient systems for in vivo gene transfer to the central nervous system (CNS) may provide a useful therapeutic strategy for the alleviation of several neurological disorders. In this study, we evaluated the feasibility of nonviral gene therapy to the CNS mediated by cationic liposomes. We present evidence of the successful delivery and expression of both a reporter and a therapeutic gene in the rodent brain, as evaluated by immunohistochemical assays. Our results indicate that transferrin-associated cationic liposome/DNA complexes (Tf-lipoplexes) allow a significant enhancement of transfection activity as compared to plain complexes, and that 8/1 (+/-) Tf-lipoplexes constitute the best formulation to mediate in vivo gene transfer. We demonstrated that Tf-lipoplex-mediated nerve growth factor transgene expression attenuates the morphological damages of the kainic acid-induced lesion as assessed by 2,3,5-triphenyltetrazolium chloride (TTC) vital staining. These findings suggest the usefulness of these lipid-based vectors in mediating the delivery of therapeutic genes to the CNS.

B Lymphocytes Participate in Cross-Presentation of Antigen following Gene Gun Vaccination

Although endocytosed proteins are commonly presented via the class II MHC pathway to stimulate CD4(+) T cells, professional APCs can also cross-present Ags, whereby these exogenous peptides can be complexed with class I MHC for cross-priming of CD8(+) T cells. Whereas the ability of dendritic cells (DCs) to cross-present Ags is well documented, it is not known whether other APCs may also play a role, or what is the relative contribution of cross-priming to the induction of acquired immunity after DNA immunization. In this study, we compared immune responses generated after gene gun vaccination of mice with DNA vaccine plasmids driven by the conventional CMV promoter, the DC-specific CD11c promoter, or the keratinocyte-specific K14 promoter. The CD11c promoter achieved equivalent expression in CD11c(+) DCs in draining lymph nodes over time, as did a conventional CMV-driven plasmid. However, immunization with DC-restricted DNA vaccines failed to generate protective humoral or cellular immunity to model Ags influenza hemagglutinin and OVA, despite the ability of CD11c(+) cells isolated from lymph nodes to stimulate proliferation of Ag-specific T cells directly ex vivo. In contrast, keratinocyte-restricted vaccines elicited comparable T and B cell activity as conventional CMV promoter-driven vaccines, indicating that cross-priming plays a major role in the generation of immune responses after gene gun immunization. Furthermore, parallel studies in B cell-deficient mu-MT mice demonstrated that B lymphocytes, in addition to DCs, mediate cross-priming of Ag-specific T cells. Collectively, these data indicate that broad expression of the immunogen is required for optimal induction of protective acquired immunity.

Montagna symposium on epidermal stem cells oligonucleotide-directed gene correction in epidermis

Oligonucleotide-directed gene alteration produces a targeted DNA sequence change in the genome of mammalian cells. The advantage of this approach is that expression of the corrected gene is regulated in the same way as a normal gene. Reliable, sensitive, and standardized assays played a critical role in the measurement of gene correction frequency among different cell types and in evaluating the structure-activity relationship of oligonucleotides. Mechanistic studies using these assays have become critical for understanding the gene repair process and setting realistic expectations on the capability of this technology. The epidermis is an ideal tissue where oligonucleotides can be administered locally and the treated sites can be monitored easily. But given the low frequency of gene correction, general selection procedures and amplification of corrected cells via epidermal stem cells are ultimately needed to make the gene repair technology practical. Recent data suggest that the in vivo application of oligonucleotides may be capable of gene correction in epidermal stem cells and the subsequent expansion of the corrected cells may result in an apparent high-level and long-lasting gene repair. Advances in oligonucleotide delivery and targeting of epidermal stem cells will be required for potential application of oligonucleotides toward treatment of genodermatoses.

Seeing the gene therapy: application of gene gun technique to transfect and decolour pigmented rat skin with human agouti signalling protein cDNA

We developed a gene gun method for the transfer of human agouti signalling protein (ASP) cDNA to alter rat skin colour in vivo. Human ASP cDNA was cloned into a modified cytomegalovirus plasmid and delivered to the skin of Long-Evans rats by gene gun bombardment. Skin pigmentation, body weight and blood sugar of ASP cDNA-transfected rats were recorded against the control group, which were injected with plasmids encoding for green fluorescent protein. The treated skin showed lighter skin colour after 3 days of ASP gene transfection. This depigmentation effect was most prominent on day 14 and the skin gradually returned to its original pigmentation by day 28. Successful transfection of ASP gene in skin and hair follicles, as well as downregulation of melanocortin-1 receptor (MC1R) and tyrosinase expression upon treatment, was confirmed using immunohistochemistry and Western blot analysis. Body weight and blood sugar in the treated rats did not show statistically significant differences as compared to control groups. These observations demonstrate that gene transfer using the gene gun method can induce high cutaneous ASP production and facilitate a switch from dark to fair colour without systemic pleiotropic effects. Such a colour switch may be that ASP is acting in a paracrine fashion. In addition, this study verifies that ASP exerts its functions by acting as an independent ligand that downregulates the melanocyte MC1R and tyrosinase protein in an in vivo system. Our result offers new, interesting insights about the effect of ASP on pigmentation, providing a novel approach to study the molecular mechanisms underlying skin melanogenesis.

Microfabricated silicon microneedles for nonviral cutaneous gene delivery

BACKGROUND

The skin represents an accessible somatic tissue for therapeutic gene transfer. The superficial lipophilic layer of the skin, the stratum corneum, however, constitutes a major obstacle to the cutaneous delivery of charged macromolecules such as DNA.

OBJECTIVES

To determine whether silicon-based microneedles, microfabricated via a novel isotropic etching/BOSCH reaction process, could generate microchannels in the skin of sufficient dimensions to facilitate access of lipid : polycation : pDNA (LPD) nonviral gene therapy vectors.

METHODS

Scanning electron microscopy was used to visualize the microconduits created in heat-separated human epidermal sheets after application of the microneedles. Following confirmation of particle size and particle surface charge by photon correlation spectrocopy and microelectrophoresis, respectively, the diffusion of fluorescent polystyrene nanospheres and LPD complexes through heat-separated human epidermal sheets was determined in vitro using a Franz-type diffusion cell. In-vitro cell culture with quantification by flow cytometry was used to determine gene expression in human keratinocytes (HaCaT cells).

RESULTS

The diffusion of 100 nm diameter fluorescent polystyrene nanospheres, used as a readily quantifiable predictive model for LPD complexes, through epidermal sheets was significantly enhanced following membrane treatment with microneedles. The delivery of LPD complexes either into or through the membrane microchannels was also demonstrated. In both cases considerable interaction between the particles and the epidermal sheet was observed. In-vitro cell culture was used to confirm that LPD complexes mediated efficient reporter gene expression in human keratinocytes in culture when formulated at the appropriate surface charge.

CONCLUSIONS

These studies demonstrate the utility of silicon microneedles in cutaneous gene delivery. Further studies are required to elucidate fully the influence of the physicochemical characteristics of gene therapy vectors, e.g. particle diameter and surface charge, on their diffusion through microchannels and to quantify gene expression in vivo.

Vectors for the treatment of autoimmune disease

Gene therapy has been applied in a variety of experimental models of autoimmunity with some success. In this article, we outline recent developments in gene therapy vectors, discuss advantages and disadvantages of each, and highlight their recent applications in autoimmune models. We also consider progress in vector targeting and components for regulating transgene expression, which will both improve gene therapy safety and empower gene therapy to fullfil its potential as a therapeutic modality. In conclusion, we consider candidate vectors that satisfy requirements for application in the principal therapeutic strategies in which gene therapy will be applied to autoimmune conditions.

Cell type-dependent divergence of transactivation by glucocorticoid receptor ligand

The glucocorticoid receptor regulates gene expression mainly by two mechanisms; transactivation and trans-repression. A ligand with strong transrepression and weak transactivation activity is predicted to be a beneficial agent with potent anti-inflammatory activity and minor adverse effects. Recently, the profile of a synthetic steroid, RU24858, has been reported to fulfill this condition in vitro, but others have reported no dissociation between the anti-inflammatory activity and side effects in vivo. To gain further information on the profile of this compound, we evaluated its transactivation ability using a reporter gene analysis both in vitro and in vivo. In the in vitro analysis, RU24858 demonstrated only a weak transactivation activity in HeLa cells, when compared with prednisolone. In CV-1 cells, however, these two glucocorticoids exhibited equivalent transactivation activities. This behavior is independent of whether the reporter gene is regulated by mouse mammary tumor virus promoter or multiple copies of glucocorticoid response element. When the reporter plasmid was inoculated into mouse abdominal skin using a gene gun, followed by orally administration of glucocorticoids, RU24858 induced significantly higher reporter enzyme activity than prednisolone. These results suggest that the profile of RU24858 is divergent and its transactivation ability is comparable to prednisolone depending on the cell-type both in vitro and in vivo.

Epidermolysis bullosa: new and emerging trends

Epidermolysis bullosa is a family of inherited blistering skin disorders characterized by blister formation in response to mechanical trauma. Major types of epidermolysis bullosa include epidermolysis bullosa simplex, hemidesmosomal epidermolysis bullosa, junctional epidermolysis bullosa, and dystrophic epidermolysis bullosa. Current treatment for epidermolysis bullosa consists of supportive care for skin and other organ systems and entails a combination of wound management, infection support for chronic wounds, surgical management as needed, nutritional support, and preventative screening for squamous cell carcinoma in recessive dystrophic epidermolysis bullosa. The regimen must be tailored specifically to the severity and extent of skin and systemic involvement in each case. Recent studies have identified specific protein and genetic abnormalities for most epidermolysis bullosa subtypes. These new advancements in the understanding of molecular pathophysiology have provided much of the basis for current efforts to develop effective gene and protein therapy for epidermolysis bullosa.

Cross-priming as a predominant mechanism for inducing CD8(+) T cell responses in gene gun DNA immunization

DNA immunization induces CD8(+) CTL responses by bone marrow-derived APCs, which are directly transfected with a plasmid DNA and/or acquire Ags from DNA-transfected non-APCs. To investigate the relative contribution of DNA-transfected APCs vs non-APCs to the initiation of CD8(+) T cell responses, we used tissue-specific promoter-directed gene expression and adoptive transfer systems in gene gun DNA immunization. In this study, we demonstrated that non-APC-specific gene expressions induced significant CD8(+) CTL and IFN-gamma-producing cells and Ab responses, whereas APC-specific gene expressions led to moderate CTL and IFN-gamma-producers, but no Ab responses. Interestingly, mice immunized with a non-APC-specific plasmid induced more rapid, vigorous, and prolonged proliferation of adoptively transferred Ag-specific CD8(+) T cells than APC-specific plasmid-immunized mice. In addition, the in vivo proliferative responses elicited by a non-APC-specific plasmid administration were dependent on TAP, but were independent of CD4(+) T cell help. Collectively, our results suggest that cross-priming, in which Ags expressed in non-APCs are taken up, processed, and presented by APCs, plays an important role in the initiation, magnitude, and maintenance of CD8(+) T cell responses in gene gun DNA immunization.