Gene therapy for rheumatoid arthritis

Targeting lymphatic function as a novel therapeutic intervention for rheumatoid arthritis

Although clinical outcomes for patients with rheumatoid arthritis (RA) have greatly improved with the use of biologic and conventional DMARDs, approximately 40% of patients do not achieve primary clinical outcomes in randomized trials, and only a small proportion achieve lasting remission. Over the past decade, studies in murine models point to the critical role of the lymphatic system in the pathogenesis and therapy of inflammatory-erosive arthritis, presumably by the removal of catabolic factors, cytokines and inflammatory cells from the inflamed synovium. Murine studies demonstrate that lymphatic drainage increases at the onset of inflammatory-erosive arthritis but, as inflammation progresses to a more chronic phase, lymphatic clearance declines and both structural and cellular changes are observed in the draining lymph node. Specifically, chronic damage to the lymphatic vessel from persistent inflammation results in loss of lymphatic vessel contraction followed by lymph node collapse, reduced lymphatic drainage, and ultimately severe synovitis and joint erosion. Notably, clinical pilot studies in patients with RA report lymph node changes following treatment, and thus draining lymphatic vessels and nodes could represent a potential biomarker of arthritis activity and response to therapy. Most importantly, targeting lymphatics represents an innovative strategy for therapeutic intervention for RA.

The pathogenesis of rheumatoid arthritis: new insights from old clinical data?

Despite their different targets, biologic agents used for blockade of TNF and IL-6, inhibition of T-cell co-stimulation and B-cell depletion all have similar beneficial effects on the outcome of rheumatoid arthritis (RA). This observation raises questions as to whether the targets of these therapies might all be involved in a common pathogenetic pathway. However, blockade of TNF and IL-6 has a similar inhibitory effect on joint damage progression in patients with either early or late disease. In comparison, B-cell depletion and inhibition of T-cell co-stimulation seem to have a somewhat delayed effect on joint damage (compared with cytokine inhibition), which suggests that these approaches affect upstream pathogenetic events. This article discusses these disparities and presents hypotheses as to whether clinical trial data can be used to determine at which point a biologic agent might interfere with the pathogenetic cascade in RA.

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.

The evolving role of gene-based treatment in surgery

Background

The completion of the sequencing of the human genome in 2003 marked the dawn of a new era of human biology and medicine. Although these remarkable scientific advances improve the understanding of human biology, the question remains how this rapidly expanding knowledge of functional genomics affects the role of surgeons. This article reviews the potential therapeutic application of gene therapy for various surgical conditions.

Methods

The core of this review was derived from a Medline database literature search.

Results and conclusion

The currently available vectors in the field of gene therapy and their limitations for clinical applications were analysed. The achievements of gene therapy in clinical trials and the future ramifications for surgery were also explored. Whether gene therapy takes a major role in surgical practice will depend greatly on the success of future vector development. Advances in viral vector technology to reduce the inflammatory effect, and improvements in the efficiency of gene delivery using non-viral vector technology, would allow this form of therapy to become more clinically applicable.

Targeting cathepsin L (CL) by specific ribozymes decreases CL protein synthesis and cartilage destruction in rheumatoid arthritis

The present study was undertaken to examine whether ribozymes cleaving specifically cathepsin L (CL) mRNA are able to decrease the synthesis of CL protease in rheumatoid arthritis synovial fibroblasts (RA-SF) and thereby reduce the invasiveness into cartilage both in vitro and in the SCID mouse coimplantation model of RA. Two different ribozymes that cleave CL mRNA specifically at positions 533 (RzCL533) and 790 (RzCL790) were generated. Using retroviral gene transfer, RA-SF were transduced with the ribozyme constructs or the empty vector. To examine the effect of the ribozymes on the mRNA level, quantitative analysis for CL mRNA was performed using real-time PCR. For evaluation on the protein level, ELISA using specific anti-CL antibodies was performed. In addition, transduced RA-SF were examined in vitro in a three-dimensional destruction assay evaluating their ability to degrade extracellular matrix produced by human chondrocytes. Matrix destruction was monitored by the release of soluble glycosaminoglycans (sGAG). Using the in vivo SCID mouse coimplantation model of RA, RzCL533-transduced RA-SF and control cells were coimplanted with human cartilage for 60 days. After being killed, invasion of RA-SF into the cartilage was evaluated by using a semiquantitative score. Transduction of RA-SF with RzCL533 and RzCL790 ribozymes decreased significantly the expression of CL mRNA to 44% (range 25-62%) and 20% (range 1-43%), respectively, when compared to mock-transduced cells. The protein concentration of CL in the cell culture supernatants of transduced RA-SF was decreased from 16.0 ng/ml in the mock constructs to 4.1 and 8.2 ng/ml (mean), respectively. Using the in vitro cartilage destruction assay, the release of sGAG decreased to 46 and 60%, respectively, after 14 days when compared to mock-transduced cells. In the SCID mouse coimplantation model of RA, RzCL533-transduced RA-SF revealed a significant lower cartilage invasion when compared to mock and untransduced cells. Using retroviral gene transfer, ribozymes cleaving CL mRNA inhibit specifically the synthesis of this matrix-degrading enzyme and reduce cartilage destruction in in vitro and in vivo models. Our study therefore suggests that ribozymes targeting CL could be a novel and efficient tool to inhibit joint destruction in RA.

Metalloproteinases: their role in arthritis and potential as therapeutic targets

Irreversible degradation of articular cartilage is a major feature of the arthritides, and its prevention is a therapeutic goal which has been difficult to achieve. Enzymes from the matrix metalloproteinase and ADAMTS (a disintegrin, a metalloproteinase, and thrombospondin motif) families are key mediators of cartilage extracellular matrix destruction. Inhibition of metalloproteinase activity is therefore a conceptually attractive therapeutic strategy, although clinical efficacy has not yet been demonstrated. This review outlines the biology behind metalloproteinases as drug targets in the arthritides, and poses important questions for the future design of such therapies.

Light-activated gene transduction enhances adeno-associated virus vector-mediated gene expression in human articular chondrocytes

OBJECTIVE

To evaluate the effects of ultraviolet (UV) light as an adjuvant for recombinant adeno-associated virus (rAAV) transduction in human articular chondrocytes.

METHODS

Primary articular chondrocytes and immortalized chondrocytes (tsT/AC62) were exposed to various doses of UV light (0-1,000 J/m(2)) and infected at various multiplicities of infection (MOIs) with rAAV containing the enhanced green fluorescent protein (EGFP) gene. Cells were analyzed for viability and EGFP expression by fluorescence-activated cell sorting on days 2, 4, and 8 following infection. To evaluate the transduction efficiency in intact articular cartilage, full-thickness explants were exposed to UV light (0-200 J/m(2)), infected with rAAV-eGFP, and analyzed for transduction via immunohistochemistry.

RESULTS

Toxicity from UV exposure was observed at doses > or =500 J/m(2) and > or =200 J/m(2) in primary and immortalized chondrocyte cultures, respectively. Transduction efficiency was dependent on the UV dose, MOI, and time. In the cell line, the adjuvant effect of UV on the percentage of cells transduced was modest, but 100 J/m(2) increased the mean fluorescence intensity (MFI) of the transduced cells 4-fold. In contrast, UV treatment had a profound effect on the transduction efficiency of primary chondrocytes, which reached approximately 100% after exposure to 100 J/m(2) of UV light and 10(3) MOIs for 8 days. Under the same conditions, 200 J/m(2) of UV light enhanced the MFI 7-fold. In cartilage explants, there was no difference in the number of transduced chondrocytes at the edge of the explants in the superficial, intermediate, or basal zones; however, 200 J/m(2) of UV light increased the transduction efficiency 2-fold at a low MOI. In the center of the explants, the superficial chondrocytes were efficiently transduced; those in the intermediate and basal zones could not be efficiently transduced under any condition. In the superficial chondrocytes, a low MOI and 200 J/m(2) of UV light increased the transduction efficiency 3-fold (to 100%).

CONCLUSION

UV light at doses of up to 200 J/m(2) (which do not significantly affect cell viability) significantly enhances the transduction efficiency and expression of the transduced gene in cultures of rAAV-infected primary chondrocytes and in chondrocytes in the superficial zone of intact articular cartilage. These findings support the concept that UV-activated gene transduction could be used as an adjuvant for in vivo rAAV articular cartilage gene therapy with low viral titers to prevent and/or treat arthritis.