Adeno-associated virus production of soluble tumor necrosis factor receptor neutralizes tumor necrosis factor alpha and reduces arthritis

Scaffold-Mediated Gene Delivery for Osteochondral Repair

Osteochondral defects involve both the articular cartilage and the underlying subchondral bone. If left untreated, they may lead to osteoarthritis. Advanced biomaterial-guided delivery of gene vectors has recently emerged as an attractive therapeutic concept for osteochondral repair. The goal of this review is to provide an overview of the variety of biomaterials employed as nonviral or viral gene carriers for osteochondral repair approaches both in vitro and in vivo, including hydrogels, solid scaffolds, and hybrid materials. The data show that a site-specific delivery of therapeutic gene vectors in the context of acellular or cellular strategies allows for a spatial and temporal control of osteochondral neotissue composition in vitro. In vivo, implantation of acellular hydrogels loaded with nonviral or viral vectors has been reported to significantly improve osteochondral repair in translational defect models. These advances support the concept of scaffold-mediated gene delivery for osteochondral repair.

Gene Delivery to Joints by Intra-Articular Injection

Most forms of arthritis are incurable, difficult to treat, and a major cause of disability in Western countries. Better local treatment of arthritis is impaired by the pharmacokinetics of the joint that make it very difficult to deliver drugs to joints at sustained, therapeutic concentrations. This is especially true of biologic drugs, such as proteins and RNA, many of which show great promise in preclinical studies. Gene transfer provides a strategy for overcoming this limitation. The basic concept is to deliver cDNAs encoding therapeutic products by direct intra-articular injection, leading to sustained, endogenous synthesis of the gene products within the joint. Proof of concept has been achieved for both in vivo and ex vivo gene delivery using a variety of vectors, genes, and cells in several different animal models. There have been a small number of clinical trials for rheumatoid arthritis (RA) and osteoarthritis (OA) using retrovirus vectors for ex vivo gene delivery and adeno-associated virus (AAV) for in vivo delivery. AAV is of particular interest because, unlike other viral vectors, it is able to penetrate deep within articular cartilage and transduce chondrocytes in situ. This property is of particular importance in OA, where changes in chondrocyte metabolism are thought to be fundamental to the pathophysiology of the disease. Authorities in Korea have recently approved the world's first arthritis gene therapy. This targets OA by the injection of allogeneic chondrocytes that have been transduced with a retrovirus carrying transforming growth factor-β₁ cDNA. Phase III studies are scheduled to start in the United States soon. Meanwhile, two additional Phase I trials are listed on Clinicaltrials.gov , both using AAV. One targets RA by transferring interferon-β, and the other targets OA by transferring interleukin-1 receptor antagonist. The field is thus gaining momentum and promises to improve the treatment of these common and debilitating diseases.

Gene therapy for human osteoarthritis: principles and clinical translation

INTRODUCTION

Osteoarthritis (OA) is the most prevalent chronic joint disease. Its key feature is a progressive articular cartilage loss. Gene therapy for OA aims at delivering gene-based therapeutic agents to the osteoarthritic cartilage, resulting in a controlled, site-specific, long-term presence to rebuild the damaged cartilage.

AREAS COVERED

An overview is provided of the principles of gene therapy for OA based on a PubMed literature search. Gene transfer to normal and osteoarthritic cartilage in vitro and in animal models in vivo is reviewed. Results from recent clinical gene therapy trials for OA are discussed and placed into perspective.

EXPERT OPINION

Recombinant adeno-associated viral (rAAV) vectors enable to directly transfer candidate sequences in human articular chondrocytes in situ, providing a potent tool to modulate the structure of osteoarthritic cartilage. However, few preclinical animal studies in OA models have been performed thus far. Noteworthy, several gene therapy clinical trials have been carried out in patients with end-stage knee OA based on the intraarticular injection of human juvenile allogeneic chondrocytes overexpressing a cDNA encoding transforming growth factor-beta-1 via retroviral vectors. In a recent placebo-controlled randomized trial, clinical scores were improved compared with placebo. These translational results provide sufficient reason to proceed with further clinical testing of gene transfer protocols for the treatment of OA.

scAAV-mediated gene transfer of interleukin-1-receptor antagonist to synovium and articular cartilage in large mammalian joints

With the long-term goal of developing a gene-based treatment for osteoarthritis (OA), we performed studies to evaluate the equine joint as a model for adeno-associated virus (AAV)-mediated gene transfer to large, weight-bearing human joints. A self-complementary AAV2 vector containing the coding regions for human interleukin-1-receptor antagonist (hIL-1Ra) or green fluorescent protein was packaged in AAV capsid serotypes 1, 2, 5, 8 and 9. Following infection of human and equine synovial fibroblasts in culture, we found that both were only receptive to transduction with AAV1, 2 and 5. For these serotypes, however, transgene expression from the equine cells was consistently at least 10-fold higher. Analyses of AAV surface receptor molecules and intracellular trafficking of vector genomes implicate enhanced viral uptake by the equine cells. Following delivery of 1 × 10(11) vector genomes of serotypes 2, 5 and 8 into the forelimb joints of the horse, all three enabled hIL-1Ra expression at biologically relevant levels and effectively transduced the same cell types, primarily synovial fibroblasts and, to a lesser degree, chondrocytes in articular cartilage. These results provide optimism that AAV vectors can be effectively adapted for gene delivery to large human joints affected by OA.

Clinical potential and challenges of using genetically modified cells for articular cartilage repair

Articular cartilage defects do not regenerate. Transplantation of autologous articular chondrocytes, which is clinically being performed since several decades, laid the foundation for the transplantation of genetically modified cells, which may serve the dual role of providing a cell population capable of chondrogenesis and an additional stimulus for targeted articular cartilage repair. Experimental data generated so far have shown that genetically modified articular chondrocytes and mesenchymal stem cells (MSC) allow for sustained transgene expression when transplanted into articular cartilage defects in vivo. Overexpression of therapeutic factors enhances the structural features of the cartilaginous repair tissue. Combined overexpression of genes with complementary mechanisms of action is also feasible, holding promises for further enhancement of articular cartilage repair. Significant benefits have been also observed in preclinical animal models that are, in principle, more appropriate to the clinical situation. Finally, there is convincing proof of concept based on a phase I clinical gene therapy study in which transduced fibroblasts were injected into the metacarpophalangeal joints of patients without adverse events. To realize the full clinical potential of this approach, issues that need to be addressed include its safety, the choice of the ideal gene vector system allowing for a long-term transgene expression, the identification of the optimal therapeutic gene(s), the transplantation without or with supportive biomaterials, and the establishment of the optimal dose of modified cells. As safe techniques for generating genetically engineered articular chondrocytes and MSCs are available, they may eventually represent new avenues for improved cell-based therapies for articular cartilage repair. This, in turn, may provide an important step toward the unanswered question of articular cartilage regeneration.

Gene Therapy for Cartilage Repair

The concept of using gene transfer strategies for cartilage repair originates from the idea of transferring genes encoding therapeutic factors into the repair tissue, resulting in a temporarily and spatially defined delivery of therapeutic molecules to sites of cartilage damage. This review focuses on the potential benefits of using gene therapy approaches for the repair of articular cartilage and meniscal fibrocartilage, including articular cartilage defects resulting from acute trauma, osteochondritis dissecans, osteonecrosis, and osteoarthritis. Possible applications for meniscal repair comprise meniscal lesions, meniscal sutures, and meniscal transplantation. Recent studies in both small and large animal models have demonstrated the applicability of gene-based approaches for cartilage repair. Chondrogenic pathways were stimulated in the repair tissue and in osteoarthritic cartilage using genes for polypeptide growth factors and transcription factors. Although encouraging data have been generated, a successful translation of gene therapy for cartilage repair will require an ongoing combined effort of orthopedic surgeons and of basic scientists.

Intra-articular gene delivery and expression of interleukin-1Ra mediated by self-complementary adeno-associated virus

BACKGROUND

The adeno-associated virus (AAV) has many safety features that favor its use in the treatment of arthritic conditions; however, the conventional, single-stranded vector is inefficient for gene delivery to fibroblastic cells that primarily populate articular tissues. This has been attributed to the inability of these cells to convert the vector to a double-stranded form. To overcome this, we evaluated double-stranded self-complementary (sc) AAV as a vehicle for intra-articular gene delivery.

METHODS

Conventional and scAAV vectors were used to infect lapine articular fibroblasts in culture to determine transduction efficiency, transgene expression levels, and nuclear trafficking. scAAV containing the cDNA for interleukin (IL)-1 receptor antagonist (Ra) was delivered to the joints of naïve rabbits and those with IL-1beta-induced arthritis. From lavage of the joint space, levels of transgenic expression and persistence were measured by enzyme-linked immunosorbent assay. Infiltrating leukocytes were quantified using a hemocytometer.

RESULTS

Transgene expression from scAAV had an earlier onset and was approximately 25-fold greater than conventional AAV despite the presence of similar numbers of viral genomes in the nuclei of infected cells. Fibroblasts transduced with scAAV produced amounts of IL1-Ra comparable to those transduced with adenoviral and lentiviral vectors. IL1-Ra was present in lavage fluid of most animals for 2 weeks in sufficient quantities to inhibit inflammation of the IL-1beta-driven model. Once lost, neither subsequent inflammatory events, nor re-administration of the virus could re-establish transgene expression.

CONCLUSIONS

scAAV-mediated intra-articular gene transfer is robust and similarly efficient in both normal and inflamed joints; the resulting transgenic expression is sufficient to achieve biological relevance in joints of human proportion.

Perspectives on the use of gene therapy for chronic joint diseases

Advances in molecular and cellular biology have identified a wide variety of proteins including targeted cytokine inhibitors, immunomodulatory proteins, cytotoxic mediators, angiogenesis inhibitors, and intracellular signalling molecules that could be of great benefit in the treatment of chronic joint diseases, such as osteo- and rheumatoid arthritis. Unfortunately, protein-based drugs are difficult to administer effectively. They have a high rate of turnover, requiring frequent readministration, and exposure in non-diseased tissue can lead to serious side effects. Gene transfer technologies offer methods to enhance the efficacy of protein-based therapies, enabling the body to produce these molecules locally at elevated levels for extended periods. The proof of concept of gene therapies for arthritis has been exhaustively demonstrated in multiple laboratories and in numerous animal models. This review attempts to condense these studies and to discuss the relative benefits and limitations of the methods proposed and to discuss the challenges toward translating these technologies into clinical realities.

Intraarticular factor IX protein or gene replacement protects against development of hemophilic synovitis in the absence of circulating factor IX

Hemophilic bleeding into joints causes synovial and microvascular proliferation and inflammation (hemophilic synovitis) that contribute to end-stage joint degeneration (hemophilic arthropathy), the major morbidity of hemophilia. New therapies are needed for joint deterioration that progresses despite standard intravenous (IV) clotting factor replacement. To test whether factor IX within the joint space can protect joints from hemophilic synovitis, we established a hemophilia B mouse model of synovitis. Factor IX knockout (FIX(-/-)) mice received a puncture of the knee joint capsule with a needle to induce hemarthrosis; human factor IX (hFIX) was either injected through the needle into the joint space (intraarticularly) or immediately delivered IV. FIX(-/-) mice receiving intraarticular FIX protein were protected from synovitis compared with mice receiving same or greater doses of hFIX IV. Next, adeno-associated virus (AAV) gene transfer vectors expressing hFIX were injected into knee joints of FIX(-/-) mice. Joints treated with 10(10) vector genomes (vg)/joint AAV2-, AAV5-, or AAV8-hFIX or 2.5 x 10(9) vg/joint AAV5-hFIX developed significantly fewer pathologic changes 2 weeks after injury compared with the pathology of control injured contralateral hind limbs. Extravascular factor activity and joint-directed gene transfer may ameliorate hemophilic joint destruction, even in the absence of circulating FIX.

IGF-1 gene therapy to protect articular cartilage in a rat model of joint damage

INTRODUCTION

An adeno-associated virus (AAV) derived vector in gene transfer model that induces IGF-1 expression could repair articular cartilage.

MATERIALS AND METHODS

Male Wistar rats, 150 and 200 g, and 7 weeks old, were used. Effectiveness of constructed vectors was assayed inoculating them in rat knees of control and damaged animals either mechanically or by collagen-induced arthritis. Inoculation was intra-articular with 50 microL of recombinant AAV-Luciferase (1.25 x 10(8) particles). The rats were killed after 1, 2, 4 and 8 weeks. IGF-I activity was analyzed by injecting 50 microL of recombinant AAV (1.25 x 10(8) particles) in animals with damaged knees. Final analysis was performed after 8 weeks.

RESULTS

The activity of AAV vectors in vitro shows the presence of mRNA coding to IGF-I in cells infected with AAV-IGF and not in control cells without viral vectors and an increase in secreted IGF-I protein in culture medium. In vivo, AAV derived vectors induced protein expression in cartilage 2 months after inoculation. In the animals killed after 1 and 2 weeks, no significant increase in the reaction of luciferase was observed (P > 0.05). In the group of animals with no injury an increase was observed at 4 weeks, which was more marked and significant after 8 weeks (P = 0.029). The same behavior occurred in the animals with induced arthritis and in the mechanical injury group. In the levels of expression after 8 weeks, no significant differences were found between the two groups of injured animals and the group of healthy animals infected with the virus. The joints of the animals that were subjected to injuries in the cartilage and inoculated with AAV-IGF-I presented a similar appearance to those animals inoculated with saline solution.

CONCLUSION

Autoimmune and mechanical lesions did not show improvement in the state of its cartilage after the treatment. The use of AAV vectors capable of inducing the expression of IGF-I in vitro is therefore not sufficient to protect the cartilage from the serious damage.

Gene therapy for arthritis

Arthritis is among the leading causes of disability in the developed world. There remains no cure for this disease and the current treatments are only modestly effective at slowing the disease's progression and providing symptomatic relief. The clinical effectiveness of current treatment regimens has been limited by short half-lives of the drugs and the requirement for repeated systemic administration. Utilizing gene transfer approaches for the treatment of arthritis may overcome some of the obstacles associated with current treatment strategies. The present review examines recent developments in gene therapy for arthritis. Delivery strategies, gene transfer vectors, candidate genes, and safety are also discussed.

Inflammation-inducible anti-TNF gene expression mediated by intra-articular injection of serotype 5 adeno-associated virus reduces arthritis

BACKGROUND

The tumor necrosis factor (TNF)-alpha plays a central role in rheumatoid arthritis (RA) and current biotherapies targeting TNF-alpha have a major impact on RA treatment. The long-term safety concerns associated with the repetitive TNF blockade prompt optimization of therapeutic anti-TNF approaches. Since we recently demonstrated that intra-articular gene transfer using a recombinant adeno-associated virus serotype 5 (rAAV5) efficiently transduces arthritic joints, we evaluate its effect on collagen-induced arthritis (CIA) when encoding TNF antagonists.

METHODS

Recombinant AAV5 vectors encoding the human TNFRp55 extracellular domain fused to the Fc region of mice IgG1 (TR1) or a small molecular weight dimeric human TNFRp75 extracellular domain (TR2), under two different promoters, the CMV or a chimeric NF-kappaB-based promoter inducible by inflammation, were injected into mouse CIA joints.

RESULTS

Best protection against arthritis was obtained with the rAAV5 encoding the TR1, as reflected by delayed disease onset, decreased incidence and severity of joint damage. This effect was associated with a transient expression of the anti-TNF agent when expressed under a NF-kappaB-responsive promoter, only detectable during disease flare, while the antagonist expression was rapidly increased and stable when expressed from a CMV promoter. Importantly, using the intra-articular administration of the rAAV5-NF-kappaB-TR1 vector, we observed a striking correlation between local TR1 expression and inflammation.

CONCLUSIONS

These findings strongly support the feasibility of improving the safety of anti-TNF approaches for the treatment of arthritis by local rAAV5-mediated gene expression under an inflammation-responsive promoter, able to provide a limited, transient and therapeutically relevant expression of anti-TNF compounds.

Synoviocyte infection with adeno-associated virus (AAV) is neutralized by human synovial fluid from arthritis patients and depends on AAV serotype

Intraarticular gene transfer with adeno-associated viral (AAV) vectors may allow efficient therapeutic transgene expression within the joint in diseases such as rheumatoid arthritis (RA), allowing high expression of the protein within the joint, preventing both systemic diffusion and side effects. However, humans demonstrate antibodies against AAV, which can influence gene transfer. To better understand critical obstacles to intraarticular gene therapy with AAV, we have previously shown that synovial fluid (SF) contains IgG to AAV that neutralizes chondrocyte infection in vitro. Our objective was therefore to compare neutralization exerted by SF from RA patients for four different AAV serotypes (AAV serotypes 1, 2, 5, and 8) on human primary synoviocytes. Serotype 2 infected synoviocytes most efficiently followed, in decreasing order, by serotypes 1, 5, and 8. SF from all patients partially inhibited infection of synoviocytes by at least one of the four serotypes. Infection with serotypes 1 and 2 was the most inhibited by SF, whereas inhibition was weak for serotypes 5 and 8. Last, we have shown that inhibition of AAV1/interleukin (IL)-4 infection of synoviocytes by SF could be reversed by increasing the number of AAV1/IL-4 particles, with a dose-dependent effect. We conclude that the most infectious AAV serotypes (1 and 2) in synoviocytes are also the serotypes most neutralized by SF. Thus, serotype 5 seems to demonstrate the best infection efficiency:immunogenicity ratio for local use in articular diseases. These data may be useful for tailoring intraarticular AAV-mediated gene therapy to individual patients.

Gene therapy for articular cartilage repair

Articular cartilage serves as the gliding surface of joints. It is susceptible to damage from trauma and from degenerative diseases. Restoration of damaged articular cartilage may be achievable through the use of cell-regulatory molecules that augment the reparative activities of the cells, inhibit the cells' degradative activities, or both. A variety of such molecules have been identified. These include insulin-like growth factor I, fibroblast growth factor 2, bone morphogenetic proteins 2, 4, and 7, and interleukin-1 receptor antagonist. It is now possible to transfer the genes encoding such molecules into articular cartilage and synovial lining cells. Although preliminary, data from in-vitro and in-vivo studies suggest that gene therapy can deliver such potentially therapeutic agents to protect existing cartilage and to build new cartilage.

Transgene Persistence and Cell Turnover in the Diarthrodial Joint: Implications for Gene Therapy of Chronic Joint Diseases

Local gene therapy for chronic joint diseases requires prolonged transgenic expression, but this has not been reliably achieved in animal models. Using normal and immunocompromised animals, we examined the capacity of various cell types in joint tissues to maintain and express exogenous transgenes after direct intra-articular gene delivery. We found that transgenic expression could persist for the lifetime of the animal but required precise immunological compatibility between the vector, transgene product, and host. It was not dependent on vector integration or promoter origin. We identified two phenotypically distinct sub-populations of genetically modified cells within the joint: (i) transient cells, with a half-life of a few weeks, and (ii) stable cells that reside in the joint tissues indefinitely. Contrary to the prevailing assumption, the transient sub-population was composed almost exclusively of synovial fibroblasts, indicating that the synovium is not an appropriate tissue upon which to base a long-term therapy. Instead, fibroblasts in the ligaments, tendons, and capsule emerged as the primary cell types capable of sustained therapeutic transgene expression. This study sheds new light on the cellular dynamics of articular tissues and suggests that cell turnover and immune reactivity are the key determinants in achieving sustained transgenic expression intra-articularly.

Reduction of arthritis following intra-articular administration of an adeno-associated virus serotype 5 expressing a disease-inducible TNF-blocking agent

BACKGROUND

In the context of preclinical development, we studied the potential of intra-articular gene delivery using a recombinant adeno-associated virus 5 (rAAV5) encoding a chimeric human tumour necrosis factoralpha (TNFalpha) soluble receptor I linked to a mouse immunoglobulin heavy chain Fc portion (TNF receptor I; TNFRI-Ig).

METHODS

Expression was under control of a nuclear factor kappa B (NFkappaB)-responsive promoter and compared with a cytomegalovirus (CMV) promoter (rAAV5.NFkappaB-TNFRI-Ig and rAAV5.CMV-TNFRI-Ig, respectively).

RESULTS

Fibroblast-like synoviocytes transduced in vitro with rAAV5.NFkappaB-TNFRI-Ig were able to produce TNFRI-Ig protein in response to several stimuli, and this was inhibited upon treatment with a specific NFkappaB blocking agent. A bioassay revealed that the synthesised TNFRI-Ig was bioactive, showing a higher affinity for human than for rat TNFalpha. Transcription of the transgene and protein production were detectable in joints injected with both constructs. No dissemination of the vector was observed outside the joints. A significant reduction in paw swelling was seen in rats treated with rAAV5.NFkappaB-TNFRI-Ig. This clinical effect was accompanied by a decrease in pro-inflammatory cytokine levels and an increase in IL10 expression in the synovium.

CONCLUSION

These results provide evidence that intra-articular gene therapy using rAAV5 encoding TNFRI-Ig may be a safe and feasible approach for the treatment of rheumatoid arthritis. The higher affinity for human TNFalpha suggests that in patients with rheumatoid arthritis the therapeutic effect might be even more pronounced than in rat adjuvant arthritis.

[Gene therapy for osteoarticular disorders]

Osteoarticular disorders are the major cause of disability in Europe and North America. It is estimated that rheumatoid arthritis affects 1 % of the population and that more than two third of people over age 55 develop osteoarthritis. Because there are no satisfactory treatments, gene therapy offers a new therapeutic approach. The delivery of cDNA encoding anti-arthritic proteins to articular cells has shown therapeutic efficacy in numerous animal models in vivo. Through the development and the experimental progresses that have been made for both rheumatoid arthritis and osteoarthritis, this review discusses the different gene therapy strategies available today and the safety issues with which they may be associated. Among the different vectors available today, adeno-associated virus seems the best candidate for a direct in vivo gene delivery approach for the treatment of joint disorders.

The use of recombinant adeno-associated virus for skeletal gene therapy

OBJECTIVES

To provide a comprehensive literature review describing recent developments of the recombinant adeno-associated virus (rAAV) vector and exploring the therapeutic application of rAAV for bone defects, cartilage lesions and rheumatoid arthritis.

DESIGN

Narrative review.

RESULT

The review outlines the serotypes and genome of AAV, integration and life cycle of the rAAV vectors, the immune response and regulating system for AAV gene therapy. Furthermore, the advancements of rAAV gene therapy for bone growth together with cartilage repair are summarized.

CONCLUSION

Recombinant adeno-associated virus vector is perceived to be one of the most promising vector systems for bone and cartilage gene therapy approaches and further investigations need to be carried out for craniofacial research.

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.

Inflammatory cytokine regulation of transgene expression in human fibroblast-like synoviocytes infected with adeno-associated virus

OBJECTIVE

An ideal gene transfer vector for chronic inflammatory diseases such as rheumatoid arthritis (RA) would provide local transgene expression only when the disease is active. To determine whether adeno-associated virus (AAV) possesses this ability, the effects of inflammatory cytokines on transgene expression were evaluated in human RA fibroblast-like synoviocytes (FLS).

METHODS

Human FLS were infected with AAV in the presence or absence of inflammatory cytokines or synovial fluid obtained from patients with RA. Transgene expression was monitored by either enzyme-linked immunosorbent assay or flow cytometry. Transgene messenger RNA (mRNA) was measured by real-time quantitative reverse transcription-polymerase chain reaction.

RESULTS

Inflammatory cytokines increased transgene expression in FLS by up to 60-fold. Synovial fluid from patients with RA, but not from patients without arthritis, was also able to increase expression in synoviocytes. Protein expression correlated with transgene mRNA levels. The enhanced expression required the continued presence of cytokines because, upon removal, transgene expression returned to baseline levels. Expression could be repeatedly reinduced by reexposure to cytokines. The effect was not promoter specific and was demonstrated to be phosphatidylinositol 3-kinase-dependent.

CONCLUSION

These results suggest that expression of a therapeutic transgene can be controlled by the presence of inflammation following AAV gene transfer, making it an attractive vector for chronic inflammatory diseases such as RA.

Complete Prevention of Atherosclerosis in ApoE-Deficient Mice by Hepatic Human ApoE Gene Transfer With Adeno-Associated Virus Serotypes 7 and 8

OBJECTIVE

Using intravenous injection of adeno-associated viral (AAV) vectors based on novel serotypes 7 and 8, we examined whether liver-specific expression of human apolipoprotein E (apoE) in apoE-deficient mice would completely prevent atherosclerosis after 1 year of sustained expression.

METHODS AND RESULTS

Chow-fed apoE-/- mice were injected via the tail vein with vectors based on AAV2 or novel serotypes AAV7 and AAV8 encoding human apoE3 driven by a liver-specific promoter. In contrast to the first-generation AAV2 vector, apoE levels of mice injected with chimeric AAV2/7 and AAV2/8 vectors reached approximately 2-fold greater than normal human plasma levels by week 4 and maintained therapeutic levels up to 1 year. Cholesterol levels of AAV2/7-apoE and AAV2/8-apoE-treated mice were reduced to normal murine wild-type levels and were maintained for 1 year. At termination after 1 year, extensive atherosclerosis was present in the thoracic aortas and aortic roots of control AAV2/8-lacZ and AAV2-apoE-injected mice, but was completely prevented in both the AAV2/7 and AAV2/8-apoE-treated mice.

CONCLUSIONS

We demonstrate that intravenous administration of AAV2/7- and AAV2/8-apoE vectors effectively mediated robust and sustained hepatic-specific expression of apoE and completely prevented atherosclerosis at 1 year.

Gene therapy for cartilage defects

Focal defects of articular cartilage are an unsolved problem in clinical orthopaedics. These lesions do not heal spontaneously and no treatment leads to complete and durable cartilage regeneration. Although the concept of gene therapy for cartilage damage appears elegant and straightforward, current research indicates that an adaptation of gene transfer techniques to the problem of a circumscribed cartilage defect is required in order to successfully implement this approach. In particular, the localised delivery into the defect of therapeutic gene constructs is desirable. Current strategies aim at inducing chondrogenic pathways in the repair tissue that fills such defects. These include the stimulation of chondrocyte proliferation, maturation, and matrix synthesis via direct or cell transplantation-mediated approaches. Among the most studied candidates, polypeptide growth factors have shown promise to enhance the structural quality of the repair tissue. A better understanding of the basic scientific aspects of cartilage defect repair, together with the identification of additional molecular targets and the development of improved gene-delivery techniques, may allow a clinical translation of gene therapy for cartilage defects. The first experimental steps provide reason for cautious optimism.

TNFR-Fc fusion protein expressed by in vivo electroporation improves survival rates and myocardial injury in coxsackievirus induced murine myocarditis

Tumor necrosis factor-alpha (TNF-alpha) is one of the major cytokines that modulate the immune response in viral myocarditis, but its role has not yet been thoroughly evaluated. We antagonized TNF-alpha using the expressed soluble p75 TNF receptor linked to the Fc portion of the human IgG1 gene (sTNFR:Fc) by in vivo electroporation, and evaluated its effects on experimental coxsackieviral B3 (CVB3) myocarditis. A plasmid DNA encoding sTNFR:Fc (15microg/mouse) was injected into the gastrocnemius muscles of Balb/C male mice followed by electroporation (day -1). Control mice were injected with an empty vector. One day after electroporation, mice were infected with CVB3 (day 0). Serum levels of sTNFR:Fc increased from day 2 and peaked at day 5 following electroporation. The heart virus titers of sTNFR:Fc mice were higher than those of controls at day 3. However, subsequent to day 12, the survival rates of the sTNFR:Fc mice were significantly higher than those of the controls (36% versus 0% at day 27, P<0.01). Histopathological examination indicated that inflammation and myocardial fibrosis were significantly decreased in sTNFR:Fc mice at day 12. The expressed sTNFR:Fc could modulate the inflammatory process during the post-viremic phase of viral myocarditis.

Treatment of human disease by adeno-associated viral gene transfer

During the past decade, in vivo administration of viral gene transfer vectors for treatment of numerous human diseases has been brought from bench to bedside in the form of clinical trials, mostly aimed at establishing the safety of the protocol. In preclinical studies in animal models of human disease, adeno-associated viral (AAV) vectors have emerged as a favored gene transfer system for this approach. These vectors are derived from a replication-deficient, non-pathogenic parvovirus with a single-stranded DNA genome. Efficient gene transfer to numerous target cells and tissues has been described. AAV is particularly efficient in transduction of non-dividing cells, and the vector genome persists predominantly in episomal forms. Substantial correction, and in some instances complete cure, of genetic disease has been obtained in animal models of hemophilia, lysosomal storage disorders, retinal diseases, disorders of the central nervous system, and other diseases. Therapeutic expression often lasted for months to years. Treatments of genetic disorders, cancer, and other acquired diseases are summarized in this review. Vector development, results in animals, early clinical experience, as well as potential hurdles and challenges are discussed.

Technology Insight: gene transfer and the design of novel treatments for rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by systemic inflammation and joint destruction. Novel therapies have emerged during the past decade, marking a new era in the treatment of RA. Meanwhile, in vivo and in vitro gene-transfer studies have provided valuable insights into mechanisms of disease pathogenesis. Advanced gene-delivery techniques and animal models promise further progress in RA research and the development of novel therapeutic strategies for this disease. In this article we provide an overview of the wide spectrum of potential targets that have been identified so far, discuss currently available gene-transfer methods, and outline the barriers that need to be overcome for these approaches to be successfully applied in daily practice.

Gene therapy for patients with rheumatoid arthritis

Gene therapy seeks either to supply a missing or dysfunctional gene or to ensure continuous long-lasting production of a therapeutic protein. Rheumatoid arthritis is a candidate for gene therapy, as the mechanisms leading to joint inflammation and destruction have been partly elucidated. Nevertheless, several crucial questions need to be addressed. Knowledge of the underlying pathophysiological mechanisms is needed to guide selection of the candidate gene. In the light of current data, TNF and IL-1 antagonists are generating interest. A choice must be made between a viral vector (adenovirus, retrovirus, adeno-associated virus) and a nonviral vector (naked DNA, administered by electrotransfer or in liposomes). Finally, the relative merits of intraarticular and systemic administration need to be considered. Safety is a primary concern. The transgene and/or vector may induce adverse effects. For instance, a transgene inserted within the host genome (when a retroviral vector is used) may induce a mutation. A number of vectors and transgenes induce immune responses. Numerous studies are ongoing to investigate the safety and efficacy of gene therapy strategies in experimental models of rheumatoid arthritis. These studies will have to be completed before further clinical trials of gene therapy in rheumatoid arthritis are considered.

Gene therapy as a therapeutic approach for the treatment of rheumatoid arthritis: innovative vectors and therapeutic genes

In recent years, significant progress has been made in the treatment of rheumatoid arthritis (RA). In addition to conventional therapy, novel biologicals targeting tumour necrosis factor-alpha have successfully entered the clinic. However, the majority of the patients still has some actively inflamed joints and some patients suffer from side-effects associated with the high systemic dosages needed to achieve therapeutic levels in the joints. In addition, due to of the short half-life of these proteins there is a need for continuous, multiple injections of the recombinant protein. An alternative approach might be the use of gene transfer to deliver therapeutic genes locally at the site of inflammation. Several viral and non-viral vectors are being used in animal models of RA. The first gene therapy trials for RA have already entered the clinic. New vectors inducing long-term and regulated gene expression in specific tissue are under development, resulting in more efficient gene transfer, for example by using distinct serotypes of viral vectors such as adeno-associated virus. This review gives an overview of some promising vectors used in RA research. Furthermore, several therapeutic genes are discussed that could be used for gene therapy in RA patients.

Ingénierie tissulaire du cartilage : état des lieux et perspectives

Lesions of the articular cartilage have a large variety of causes among which traumatic damage, osteoarthritis and osteochondritis dissecans are the most frequent. Returning damaged cartilage in articular joints back to a functionally normal state has been a major challenge for orthopaedic surgeons. This interest results in large part because cartilage defects cannot adequately heal themselves. Current techniques used in orthopaedic practice to repair cartilage give variable and unpredictable results. Bone marrow stimulation techniques such as abrasion arthroplasty, drilling and microfracture produce mostly fibrocartilage. Autologous osteochondral transplant systems (mosaicplasty) have shown encouraging results. Autologous chondrocyte transplantation has led to a hyaline articular cartilage repair but little is known about the predictability and reliability of the procedure. The rapidly emerging field of tissue engineering promises creation of viable substitutes for failing cartilage tissue. Current tissue engineering approaches are mainly focused on the restoration of pathologically altered tissue structure based on the transplantation of cells in combination with supportive matrices and molecules. Among natural and synthetic matrices, collagen and polysaccharidic biomaterials have been extensively used with promising results. Recently, interest has switched to the use of mesenchymal stem cells instead of chondrocytes. Tissue engineering offers the possibility to treat localised cartilage lesions. Genetic engineering techniques using genetically modified chondrocytes offer also the opportunity to treat diffuse cartilage lesions occurring in osteoarthritis or inflammatory joint diseases. Electroporation is specially a reliable and inexpensive technique that shares with electrochemotherapy an ability to target the chondrocytes despite the barrier effect of the extracellular matrix without viral vectors. The authors review recent research achievements and highlight the potential clinical applications of new technologies in the treatment of patients with cartilage injuries.

Proteasome inhibition enhances AAV-mediated transgene expression in human synoviocytes in vitro and in vivo

To explore the potential applicability of recombinant adeno-associated virus (rAAV) vectors in the treatment of rheumatoid arthritis (RA), primary human fibroblast-like synoviocytes (FLS) derived from patients with RA were infected with rAAV encoding mouse IL-10 under the control of the CMV promoter. Addition of the proteasome inhibitor carbobenzoxy-l-leucyl-l-leucyl-l-leucinal (zLLL) to the cultures dramatically enhanced expression of the IL-10 transgene, in a dose-dependent manner. The increased expression was transient, peaking at 3 days and returning to near baseline by 7 days. The enhancement was observed even when zLLL was added 13 days after infection with rAAV. The effect of zLLL was not specific to either the mIL-10 transgene or the CMV promoter, as similar findings were observed using an rAAV construct encoding alpha1-anti-trypsin under the control of the chick beta-actin promoter or GFP, driven by the CMV promoter. Transgene expression could be repeatedly induced by reexposure to zLLL. Transgene mRNA levels increased in parallel with protein levels. Transgene expression could also be repeatedly induced in vivo by administering zLLL to SCID mice previously injected with rAAV-infected FLS. These data demonstrate that proteasome inhibition can dramatically enhance transgene expression in human RA FLS following infection with rAAV and suggest a possible approach to regulating synovial transgene expression in vivo.

Enhanced gene transfer to arthritic joints using adeno-associated virus type 5: implications for intra-articular gene therapy

BACKGROUND

Gene therapy of the joint has great potential as a new therapeutic approach for the treatment of rheumatoid arthritis (RA). The vector chosen is of crucial importance for clinical success.

OBJECTIVE

To investigate the tropism and transduction efficiency in arthritic joints in vivo, and in synovial cells in vitro, using five different serotypes of recombinant adeno-associated virus (rAAV) encoding beta-galactosidase or green fluorescent protein genes.

METHODS

rAAV was injected into the ankle joints of rats with adjuvant arthritis after the onset of disease. Synovial tissue was examined at different time points for beta-galactosidase protein and gene expression by in situ staining and polymerase chain reaction (PCR) analysis, respectively. In addition, the ability of rAAV to transduce primary human fibroblast-like synoviocytes from patients with RA was investigated in vitro.

RESULTS

Intra-articular injection of the rAAV5 serotype resulted in the highest synovial transduction, followed by much lower expression using rAAV2. Expression of the transgene was already detectable 7 days after injection and lasted for at least 4 weeks. Only background staining was seen for serotypes 1, 3, and 4. Importantly, there was a minimal humoral immune response to rAAV5 compared with rAAV2. Additionally, it was found that both rAAV2 and rAAV5 can efficiently transduce human fibroblast-like synoviocytes obtained from patients with RA.

CONCLUSION

Intra-articular rAAV mediated gene therapy in RA might be improved by using rAAV5 rather than other serotypes.

Adeno-Associated Virus Pseudotype 5 Vector Improves Gene Transfer in Arthritic Joints

The potential for gene delivery to joints, using recombinant adeno-associated virus (rAAV) vectors for the treatment of rheumatoid arthritis (RA), has received much attention. Different serotypes have different virion shell proteins and, as a consequence, vary in their tropism for diverse tissues. The aim of this study was to compare the transduction efficiency of different AAV serotypes encoding murine secreted alkaline phosphatase (mSEAP) or Escherichia coli beta-galactosidase for intraarticular gene delivery in an experimental model of arthritis. The vectors contained AAV2 terminal repeats flanking the reporter gene in an AAV1, AAV2, or AAV5 capsid, producing the pseudotypes rAAV-2/1, rAAV-2/2, and rAAV-2/5. Left knee joints of mice with collagen-induced arthritis were injected and transgene expression was analyzed by chemiluminescence or direct in situ staining of frozen sections. We show for the first time that intraarticular gene transfer with AAV- 2/5 was far more efficient than with the other serotypes tested. Transgene expression was detectable as early as 7 days after injection, reached a maximum at 21 days, and was stably expressed for at least 130 days, whereas AAV-2/1- and AAV-2/2-mediated expression levels were barely detectable. These findings provide a practical application for future local AAV-mediated gene therapy trials in RA.

A model of inflammatory arthritis highlights a role for oncostatin M in pro-inflammatory cytokine-induced bone destruction via RANK/RANKL

Oncostatin M is a pro-inflammatory cytokine previously shown to promote marked cartilage destruction both in vitro and in vivo when in combination with IL-1 or tumour necrosis factor alpha. However, the in vivo effects of these potent cytokine combinations on bone catabolism are unknown. Using adenoviral gene transfer, we have overexpressed oncostatin M in combination with either IL-1 or tumour necrosis factor alpha intra-articularly in the knees of C57BL/6 mice. Both of these combinations induced marked bone damage and markedly increased tartrate-resistant acid phosphatase-positive multinucleate cell staining in the synovium and at the front of bone erosions. Furthermore, there was increased expression of RANK and its ligand RANKL in the inflammatory cells, in inflamed synovium and in articular cartilage of knee joints treated with the cytokine combinations compared with expression in joints treated with the cytokines alone or the control. This model of inflammatory arthritis demonstrates that, in vivo, oncostatin M in combination with either IL-1 or tumour necrosis factor alpha represents cytokine combinations that promote bone destruction. The model also provides further evidence that increased osteoclast-like, tartrate-resistant acid phosphatase-positive staining multinucleate cells and upregulation of RANK/RANKL in joint tissues are key factors in pathological bone destruction.

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.

Local adeno-associated virus-mediated interleukin 10 gene transfer has disease-modifying effects in a murine model of Sjögren's syndrome

Female nonobese diabetic (NOD) mice develop spontaneous autoimmune sialadenitis and loss of salivary flow, and are a widely used model of Sjögren's syndrome. We examined the feasibility of local salivary gland immunomodulatory gene delivery to alter these sequelae in NOD mice. We constructed recombinant adeno-associated virus (rAAV) vectors encoding either human interleukin 10 (rAAVhIL-10) or beta-galactosidase (rAAVLacZ, control vector). Mice received rAAVhIL-10 or rAAVLacZ by retrograde submandibular ductal instillation either at age 8 weeks (early, before onset of sialadenitis), or at 16 weeks (late, after onset of sialadenitis). As a systemic treatment control, separate mice received intramuscular delivery of rAAVhIL-10 at each time point. Both submandibular and intramuscular delivery of vector led to low circulating levels of hIL-10. After submandibular administration of rAAVhIL-10, salivary flow rates at 20 weeks for both the early and late treatment groups were significantly higher than for both rAAVLacZ-administered and untreated mice. Systemic delivery of rAAVhIL-10 led to improved salivary flow in the late treatment group. Inflammatory infiltrates in submandibular glands, however, were significantly reduced only in mice receiving rAAVhIL-10 locally in the salivary gland compared with mice receiving this vector intramuscularly, or rAAVLacZ or no treatment. In addition, after submandibular rAAVhIL-10 delivery, NOD mice exhibited significantly lower blood glucose, and higher serum insulin, levels than all other groups, indicating some systemic benefit of this treatment. These studies show that expression of hIL-10 by rAAV vectors can have disease-modifying effects in the salivary glands of NOD mice, and suggest that local immunomodulatory gene transfer may be useful for managing the salivary gland pathology in Sjögren's syndrome.

Gene Therapy of Collagen-Induced Arthritis by Electrotransfer of Human Tumor Necrosis Factor-αSoluble Receptor I Variants

Electrotransfer is a simple and efficient strategy of nonviral gene delivery. We have used this method to deliver plasmids encoding three human tumor necrosis factor-alpha soluble receptor I variants (hTNFR-Is) a monomeric hTNFR-Is, a chimeric hTNFR-Is/mIgG1, and a dimeric (hTNFR-Is)(2) form. Electrotransfer parameters were studied and because anti-TNF strategies have proven efficient for the treatment of rheumatoid arthritis in clinics, we used a collagen-induced arthritis (CIA) mouse model to assess the efficacy of our constructs in the treatment of the disease. All proteins were proven bioactive, both in vitro and ex vivo. Plasmid intramuscular electrotransfer in mice resulted in a local expression of the three variants for at least 6 months; systemic expression lasted also more than 6 months for the hTNFR-Is/mIgG1 form, while it was shorter for the two other forms. This expression was plasmid dose-dependent. Electrotransfer of 50 microg of hTNFR-Is/mIgG1 at the onset of a CIA induced a clear-cut decrease in both clinical and histologic signs of the disease; the dimeric form also showed some efficacy. Moreover, the long-lasting protective effect was observed for more than 5 weeks. Comparison of this electrotransfer approach with repeated recombinant protein (etanercept) injections highlighted the potential practical interest of gene therapy approach for CIA, which leads to sustained therapeutic effect after single treatment. These results show that electrotransfer may be a useful method to deliver cytokine or anticytokine therapy in rheumatoid arthritis and also illustrate the potentiality of plasmid intramuscular electrotransfer for the rapid screening and assessment of different variant forms of secreted proteins.

Gene therapies for osteoarthritis

Osteoarthritis (OA) is a major health problem in urgent need of better treatment. Gene therapy offers to meet this need. Of the different strategies for using gene therapy in OA, local gene transfer to synovium is in the most advanced stage of development. Local gene transfer brings several advantages, including a focused, local therapy that promises greater efficacy with reduced side-effects, potentially at far lower cost. Moreover, its clinical feasibility has already been confirmed in two Phase I studies of gene therapy for rheumatoid arthritis. Although there are numerous candidate genes of potential use in treating OA genetically, considerable evidence identifies interleukin-1 (IL-1) as a key target. The existence of a natural antagonist, the IL-1 receptor antagonist (IL-1Ra), provides a means with which to inhibit its biologic actions. Clinical studies are suggested in which IL-1Ra complementary DNA is transferred to knee joints shortly before they are surgically replaced with prostheses. This will permit the ready assessment of the safety and efficiency of gene transfer and expression in the human OA knee, as well as permitting preliminary functional data to be obtained, as a prelude to phase II efficacy studies. At this point, the major barriers to progress are financial rather than intellectual or technical.

CII-DC-AdTRAIL cell gene therapy inhibits infiltration of CII-reactive T cells and CII-induced arthritis

Previously, we described an APC-adenovirus (APC-Ad) FasL cell gene therapy method which could be used to deplete autoreactive T cells in vivo. FasL was toxic, however, and controlled regulation of FasL was not achieved. Here we describe an improved approach to delivering TNF-related apoptosis-inducing ligand (TRAIL) in vivo in which collagen II-induced (CII-induced) arthritis-susceptible (CIA-susceptible) DBA/1j mice were treated with CII-pulsed DCs that had been transfected with a novel Ad system. The Ad was engineered to exhibit inducible TRAIL under the control of the doxycycline-inducible (DOX-inducible) tetracycline response element (TRE). Four groups of mice were treated with CII-DC-AdTRAIL+DOX, CII-DC-AdTRAIL (no DOX), CII-DC-AdGFP+DOX, or DC-AdTRAIL+DOX (no CII), beginning 2 weeks after priming with CII in CFA. The incidence of arthritis and infiltration of T cells in the joint was significantly decreased in CII-DC-AdTRAIL+DOX-treated mice. The in vitro splenic T cell proliferative response and induction of IFN-gamma to bovine CII stimulation were also significantly reduced in mice treated with CII-DC-AdTRAIL+DOX. AdTRAIL+DOX was not toxic to DCs or mice but could induce activated T cells to undergo apoptosis in the spleen. Our results suggest that CII-DC-AdTRAIL+DOX cell gene therapy is a safe and effective method for inhibiting the development of CIA.

Advances in vector-mediated gene transfer

Clinical applications of gene transfer technology initially targeted the treatment of inherited monogenetic disorders and cancers refractory to conventional therapies. Today, gene transfer approaches are being developed for most tissues and for multiple disorders including those affecting quality of life. The focus herein is eventual application of gene transfer technology for the management of organ-directed autoimmunity. A specific example is presented: Sjögren's syndrome and localized salivary gland gene transfer. The status of relevant pre-clinical gene transfer studies is reviewed, with an emphasis on use of adenoviral and adeno-associated viral vectors. Current limitations of effective organ-directed gene transfer are also discussed.