Constitutive intra-articular expression of human IL-1 beta following gene transfer to rabbit synovium produces all major pathologies of human rheumatoid arthritis.

To investigate the pathophysiologic effects of chronically elevated intra-articular levels of IL-1 beta, we used an ex vivo gene transfer method to deliver and express human IL-1 beta (hIL-1 beta) in the knee joints of rabbits. Expression of hIL-1 beta resulted in a severe, highly aggressive form of arthritis analogous to chronic rheumatoid arthritis in humans. Intra-articular manifestations included intense inflammation, leukocytosis, synovial hypertrophy and hyperplasia, and highly aggressive pannus formation with erosion of the articular cartilage and periarticular bone. Systemic effects were also observed, including diarrhea, fever, weight loss, and an increased erythrocyte sedimentation rate. In addition, the hIL-1 beta was found to induce elevated levels of both rabbit IL-1 beta and TNF-alpha in synovial fluid. Following the loss of hIL-1 beta transgene expression between 14 and 28 days post-transplantation, many of these changes began to normalize. These results suggest that chronically elevated intra-articular levels of IL-1 beta alone are sufficient to produce virtually all the pathologies found in rheumatoid arthritis, and furthermore, demonstrate that gene transfer can be used to investigate the roles of specific gene products in the pathogenesis of arthritis.

Suppression of intra-articular responses to interleukin-1 by transfer of the interleukin-1 receptor antagonist gene to synovium.

We have developed an ex vivo method for delivering genes to the synovial lining of joints and expressing them intra-articularly. The present studies were designed to determine whether transfer of a human interleukin-1 receptor antagonist protein (IRAP) gene by this method was able to antagonize the intra-articular actions of interleukin-1. Intra-articular injections of human recombinant interleukin-1 beta (hrIL-1 beta) into the knees of control rabbits provoked a marked leukocytic infiltrate into the joint space, severe synovial thickening and hypercellularity, and loss of proteoglycans from articular cartilage. Genetically modified knees contained several nanograms of human IRAP and inhibited each of these effects of IL-1 beta. These data demonstrate for the first time that delivery of an appropriate gene to joints can prevent intra-articular pathology. Such findings permit cautious optimism about the eventual development of a gene treatment for arthritis and other disorders of the joint.

Intraarticular expression of biologically active interleukin 1-receptor-antagonist protein by ex vivo gene transfer.

Gene therapy offers a radical different approach to the treatment of arthritis. Here we have demonstrated that two marker genes (lacZ and neo) and cDNA coding for a potentially therapeutic protein (human interleukin 1-receptor-antagonist protein; IRAP or IL-1ra) can be delivered, by ex vivo techniques, to the synovial lining of joints; intraarticular expression of IRAP inhibited intraarticular responses to interleukin 1. To achieve this, lapine synoviocytes were first transduced in culture by retroviral infection. The genetically modified synovial cells were then transplanted by intraarticular injection into the knee joints of rabbits, where they efficiently colonized the synovium. Assay of joint lavages confirmed the in vivo expression of biologically active human IRAP. With allografted cells, IRAP expression was lost by 12 days after transfer. In contrast, autografted synoviocytes continued to express IRAP for approximately 5 weeks. Knee joints expressing human IRAP were protected from the leukocytosis that otherwise follows the intraarticular injection of recombinant human interleukin 1 beta. Thus, we report the intraarticular expression and activity of a potentially therapeutic protein by gene-transfer technology; these experiments demonstrate the feasibility of treating arthritis and other joint disorders with gene therapy.