A tRNACys-aptamer chimera co-targeting ADAMTS5 and Ptgs2 interrupts the ECM-pyroptosis feedback loop in osteoarthritis

Osteoarthritis (OA) is driven by a self-amplifying cycle of extracellular matrix (ECM) destruction and inflammatory cell death, yet disease-modifying therapies remain unavailable. Here, we engineer a multifunctional RNA chimera (CA5) by fusing a humanized tRNA Cys anticodon stem-loop scaffold with an ADAMTS5 aptamer, thereby integrating protease inhibition with small RNA-like post-transcriptional regulation within a single RNA molecule. In IL-1β-stimulated chondrocytes, CA5 mitigates aggrecan and collagen degradation, suppresses inflammatory mediators, and robustly inhibits pyroptosis, exhibiting pronounced synergy between the tRNA Cys scaffold and the aptamer domain. Consistent with these in vitro findings, intra-articular administration of CA5 in the destabilization of the medial meniscus (DMM) mouse model preserves articular cartilage, alleviates synovitis, and limits subchondral bone deterioration without detectable systemic toxicity. Mechanistically, structural and biophysical analyses demonstrate that CA5 adopts a stable G-quadruplex-containing architecture and binds ADAMTS5, enabling potent blockade of aggrecanase. Moreover, CA5 undergoes intracellular processing to release a conserved 3ꞌtRNA-derived fragment (3ꞌtRF) that directly targets the 3ꞌUTR of Ptgs2 mRNA, leading to Ptgs2 repression and subsequent attenuation of NF-κB signaling, thereby breaking the ECM-pyroptosis feedback loop. Collectively, CA5 represents a dual-action, single-molecule RNA therapeutic that couples aptamer-mediated ADAMTS5 inhibition with 3ꞌtRF-driven Ptgs2 silencing to counteract OA pathogenesis, offering a modular strategy for next-generation OA interventions.