Abstract
The interleukin (IL)-1 pathway is a key mediator of inflammation and innate immune responses. Its dysregulation contributes to rheumatoid arthritis (RA) and autoinflammatory diseases (AIDs). In this study, we develop a recombinant adeno-associated virus (rAAV)-based gene therapy to deliver an inflammation-inducible, secreted human IL-1 receptor antagonist (sIL-1Ra) as a complementary approach to existing IL-1 blockers. rAAV-mediated expression of sIL-1Ra dampens IL-1 signaling and inflammatory arthritis in mice. As the expression of endogenous sIL-1Ra is tightly regulated by inflammation, we developed an rAAV vector that produces sIL-1Ra in response to pro-inflammatory cytokines and bone morphogenic proteins (BMPs) enriched in the inflamed joints of patients with RA. Remarkably, inflammation-inducible sIL-1Ra is more effective than constitutively expressed sIL-1Ra in ameliorating inflammatory arthritis in the mouse model of RA. These mice showed a significant reduction in circulating immune cells, expression of the genes associated with inflammatory responses, joint swelling, and bone destruction. Similar to patients with deficiency of IL-1Ra (DIRA), IL-1Ra-deficient mice spontaneously develop inflammatory arthritis and skeletal abnormalities, which are almost completely reversed by a single systemic administration of the sIL-1Ra-expressing rAAV vector. Collectively, our results highlight inflammation-inducible IL-1-targeted therapy using an rAAV vector as a long-lasting, pathophysiologic treatment for chronic inflammatory diseases.