Steven C. Ghivizzani

Viral Vectors for Gene Therapy

Viruses have evolved to become highly efficient at nucleic acid delivery to specific cell types while avoiding immunosurveillance by an infected host. These properties make viruses attractive gene-delivery vehicles, or vectors, for gene therapy. Several types of viruses, including retrovirus, adenovirus, adeno-associated virus (AAV), and herpes simplex virus, have been modified in the laboratory for use in gene therapy applications. Because these vector systems have unique advantages and limitations, each has applications for which it is best suited. Retroviral vectors can permanently integrate into the genome of the infected cell, but require mitotic cell division for transduction. Adenoviral vectors can efficiently deliver genes to a wide variety of dividing and nondividing cell types, but immune elimination of infected cells often limits gene expression in vivo. Herpes simplex virus can deliver large amounts of exogenous DNA; however, cytotoxicity and maintenance of transgene expression remain as obstacles. AAV also infects many nondividing and dividing cell types, but has a limited DNA capacity. Alternatively, chimeric viral-vector systems that combine advantageous properties of two or more viral systems are also being explored. Although viral-mediated gene delivery has proved to be the most efficient means of gene transfer, nonviral means are also under development. Many of these nonviral systems incorporate portions of viral vectors to increase the efficiency of gene delivery or expression. Retrovirus, adenovirus, and AAV vectors are being evaluated currently in several Phase 1 clinical trials for treatment of diseases such as cancer, cystic fibrosis, Gaucher disease, and arthritis.

Viral vectors for gene therapy

Viruses have evolved to become highly efficient at nucleic acid delivery to specific cell types while avoiding immunosurveillance by an infected host. These properties make viruses attractive gene-delivery vehicles, or vectors, for gene therapy. Several types of viruses, including retrovirus, adenovirus, adeno-associated virus (AAV), and herpes simplex virus, have been modified in the laboratory for use in gene therapy applications. Because these vector systems have unique advantages and limitations, each has applications for which it is best suited. Retroviral vectors can permanently integrate into the genome of the infected cell, but require mitotic cell division for transduction. Adenoviral vectors can efficiently deliver genes to a wide variety of dividing and nondividing cell types, but immune elimination of infected cells often limits gene expression in vivo. Herpes simplex virus can deliver large amounts of exogenous DNA; however, cytotoxicity and maintenance of transgene expression remain as obstacles. AAV also infects many nondividing and dividing cell types, but has a limited DNA capacity. Alternatively, chimeric viral-vector systems that combine advantageous properties of two or more viral systems are also being explored. Although viral-mediated gene delivery has proved to be the most efficient means of gene transfer, nonviral means are also under development. Many of these nonviral systems incorporate portions of viral vectors to increase the efficiency of gene delivery or expression. Retrovirus, adenovirus, and AAV vectors are being evaluated currently in several Phase 1 clinical trials for treatment of diseases such as cancer, cystic fibrosis, Gaucher disease, and arthritis.

Effective Treatment of Established Murine Collagen-Induced Arthritis by Systemic Administration of Dendritic Cells Genetically Modified to Express IL-4

Dendritic cells (DC) are APCs that are able to stimulate or inhibit immune responses, depending on levels of expression of MHC class I and II costimulatory molecules and cytokines. Our previous studies have suggested that the observed contralateral effect, where injection of a vector carrying certain immunomodulatory genes into one joint resulted in inhibition of arthritis in untreated joints, is mediated by in vivo modification of DC. Therefore, we have examined the ability of genetically modified DC to suppress established murine collagen-induced arthritis (CIA) after i.v. delivery. IL-4 has been shown to partially reduce the severity of CIA after repeated injection of recombinant protein or by injection of an adenoviral vector expressing IL-4. Here we demonstrate that i.v. injection of immature DC, infected with an adenoviral vector expressing IL-4, into mice with established CIA resulted in almost complete suppression of disease, with no recurrence for up to 4 wk posttreatment. Injection i.v. of fluorescently labeled DC demonstrated that the cells rapidly migrated to the liver and spleen after 6 h and to the lymph nodes by 24 h. In culture, spleen cells from DC/IL-4-treated mice produced less IFN-γ after stimulation by collagen than did control groups. In addition, DC/IL-4 administration decreased the level of specific Abs against type II collagen, in particular the IgG2 Th1 isotype 14 days posttreatment. These results demonstrate the ability to treat effectively established murine arthritis by systemic administration of DC expressing IL-4.

Adenovirus‐mediated gene transfer of insulin‐like growth factor 1 stimulates proteoglycan synthesis in rabbit joints

OBJECTIVEnTo examine the effect of insulin-like growth factor 1 (IGF-1) on the regulation of cartilage synthesis and other articular events in vivo.nnnMETHODSnA first-generation adenoviral vector expressing human IGF-1 (AdIGF-1) from the cytomegalovirus promoter was constructed. Particles of AdIGF-1 (5 x 10(9)) were injected through the patellar tendon into normal rabbit knee joints and rabbit knee joints with antigen-induced arthritis (AIA), with the same dose of a control adenoviral vector injected into the contralateral knees. Lavage fluids were obtained from rabbit knee joints on days 3 and 7 postinjection and used for analysis of IGF-1 expression, white blood cell infiltration, and cartilage breakdown. Cartilage chips from rabbit joints were used for assay of new proteoglycan synthesis, and tissues also were harvested from the dissected knees for histologic study.nnnRESULTSnIntraarticular injection of AdIGF-1 resulted in a mean of 180.6 ng/ml of IGF-1 expression in the lavage fluid from rabbit joints. IGF-1 expression stimulated new proteoglycan synthesis in both naive and AIA rabbit knees, but had no significant chondroprotective or antiinflammatory effects. Histologic analysis showed that elevated levels of IGF-1 expression in both normal and arthritic knees had no adverse pathologic effects on synovium or adjacent muscles.nnnCONCLUSIONnGene transfer of IGF-1 into rabbit knee joints promotes proteoglycan synthesis without significantly affecting inflammation or cartilage breakdown. In addition, no adverse effects following intraarticular IGF-1 gene delivery were observed. Thus, local gene transfer of IGF-1 to joints could serve as a therapeutic strategy to stimulate new matrix synthesis in both rheumatoid arthritis and osteoarthritis.

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

To examine the effect of transforming growth factor (TGF)-β1 on the regulation of cartilage synthesis and other articular pathologies, we used adenovirus-mediated intra-articular gene transfer of TGF-β1 to both naïve and arthritic rabbit knee joints. Increasing doses of adenoviral vector expressing TGF-β1 were injected into normal and antigen-induced arthritis rabbit knee joints through the patellar tendon, with the same doses of an adenoviral vector expressing luciferase injected into the contralateral knees as the control. Intra-articular injection of adenoviral vector expressing TGF-β1 into the rabbit knee resulted in dose-dependent TGF-β1 expression in the synovial fluid. Intra-articular TGF-β1 expression in both naïve and arthritic rabbit knee joints resulted in significant pathological changes in the rabbit knee as well as in adjacent muscle tissue. The observed changes induced by elevated TGF-β1 included inhibition of white blood cell infiltration, stimulation of glycosaminoglycan release and nitric oxide production, and induction of fibrogenesis and muscle edema. In addition, induction of chondrogenesis within the synovial lining was observed. These results suggest that even though TGF-β1 may have anti-inflammatory properties, it is unable to stimulate repair of damaged cartilage, even stimulating cartilage degradation. Gene transfer of TGF-β1 to the synovium is thus not suitable for treating intra-articular pathologies.

Intra-articular adenoviral-mediated gene transfer of trail induces apoptosis of arthritic rabbit synovium

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease that primarily affects joints. In rheumatoid joints there is extensive synovial proliferation with diseased synovium becoming highly aggressive, attaching to the articular cartilage and bone to form what is termed a pannus. The formation of active pannus is central to erosive disease and resulting joint destruction. In this study, we examined the ability to eliminate the hyperplastic synovium by adenoviral-mediated gene transfer of human TNF-related apoptosis-inducing ligand (TRAIL), a member of the TNF family that is able to induce apoptosis through interaction with receptors containing death domains, DR4 and DR5. Infection of synovial cells derived from RA patients with Ad.TRAIL resulted in significant apoptosis in three out of five lines. Moreover, primary rabbit synovial fibroblasts were also sensitive to Ad.TRAIL-mediated gene transfer. In a rabbit model of arthritis, intra-articular gene transfer of TRAIL induced apoptosis in cells within the synovial lining, reduced leukocytic infiltration and stimulated new matrix synthesis by cartilage. These results demonstrate that TRAIL can affect the viability of the cells populating the activated synovium in arthritic joints and suggest that the delivery of TRAIL to arthritic joints may represent a non-invasive mechanism for inducing pannus regression.

Adenoviral mediated delivery of FAS ligand to arthritic joints causes extensive apoptosis in the synovial lining

Rheumatoid arthritis (RA) is an autoimmune disease where the synovial lining layer of the joint becomes thickened, hypercellular, and highly aggressive. Invading synovial tissue erodes cartilage and subchondral bone and leads to loss of joint function. FasL, a cell‐surface molecule on activated T‐cells interacts with its receptor, Fas, to induce apoptosis in target cells. We addressed the feasibility of using adenoviral gene transfer of FasL therapeutically to mediate apoptosis in arthritic joints similar in size to the small joints of the hands and feet that are the primary sites of RA in humans.

The efficiency of muscle-derived cell-mediated bone formation.

The development of new clinically applicable methods for the delivery of bone morphogenic protein (BMP) is an area of intensive research. Cell-mediated gene therapy approaches are being explored as a potential delivery vehicle. Primary muscle-derived cells isolated from an adult mouse were transduced with an adenoviral–BMP-2 construct. These cells were injected into the triceps surae of severe combined immune deficient (SCID) mice where they induced heterotopic bone formation. BMP-2 expression by these muscle-derived cell constructs was measured in vitro to estimate in vivo BMP-2 delivery. In vitro expression of BMP-2 by 3 × 105 muscle-derived cells was 87.89 ng/72 h. These results suggest that the efficiency of muscle cell-based gene delivery of BMP-2 exceeds the direct delivery of recombinant BMP-2 protein.

Lessons learned from gene transfer approaches

Recent technological advances allow the transfer of genes to the synovial lining of joints. As well as opening novel opportunities for therapy, these techniques provide valuable new tools for the study of synovitis and other aspects of the biology of joints in health and disease. This article reviews briefly the results of experiments in which selected genes have been transferred to the knee joints of healthy rabbits and rabbits with antigen-induced arthritis.

Vectors for Gene Transfer to Joints

Gene therapy represents a novel approach for treating joint and bone disorders (Evans et al. 1997; Evans, Ghivizzani, and Robbins 1998; Lattermann et al. 1998). As discussed in other chapters, gene transfer can be used for delivering therapeutic agents to synovium, cartilage, ligaments, tendons, meniscus, intervertebral disc, and bone to block disease progression or to promote repair. In addition, the recent completion of the first gene therapy trial for rheumatoid arthritis (RA) has demonstrated the feasibility of using gene transfer for the treatment of orthopaedic and rheumatologic disorders. The use of gene transfer to deliver a therapeutic agent offers certain advantages over the use of recombinant protein. In particular, the use of genes as therapeutic agents can results in persistent expression locally at the site of disease, bypassing the need for multiple injections and preventing possible side effects associated with systemic administration.