Background/Purpose: Adenosine is a potent endogenous modulator of inflammation; however, its clinical application is limited due to its extremely short half-life in blood. In this study, we identified an optimal anti-inflammatory adenosine-guanosine-based oligonucleotide, which was encapsulated in PLGA-based nanoparticles to enhance in vivo stability. We further examined its effects on surgically induced osteoarthritis (OA) models and evaluated the underlying mechanisms responsible for its anabolic effects.

Methods: Approximately 500 oligonucleotides, each about 20 mer in length, were screened for their anti-inflammatory effects by measuring nitric oxide (NO) production in THP-1 cells stimulated with lipopolysaccharide (LPS). The oligonucleotide that most significantly reduced NO production was chosen as a candidate and encapsulated in PLGA nanoparticles using the NanoAssemblr Ignite microfluidic system. The characteristics of these nanoparticles were confirmed through electron microscopy, zeta potential, and particle size analysis. Primary chondrocytes were obtained from the growth plates of the proximal tibia and distal femur of 5-day-old WT C57BL/6J mice. Surgical OA was induced in 12-week-old male WT C57BL/6J mice and 12-week-old Sprague-Dawley rats by destabilization of the medial meniscus (DMM) and resection of the anterior cruciate ligament (ACL), respectively. The oligonucleotides encapsulated in PLGA nanoparticles were injected intra-articularly at concentrations of 0.2 or 1 μg/μL at 1, 3, 5, and 7 weeks.

Results: The size of the PLGA nanoparticles containing the oligonucleotide was approximately 173 ± 125 nm, and they exhibited a zeta potential of around -44 mV. When treated with primary chondrocytes, no cytotoxicity was observed up to 200 nM, though it was evident at 2000 nM. Intra-articular injection of nanoparticles containing the oligonucleotide demonstrated significant resistance to cartilage damage and reduced pain behaviors in DMM model of mice and in ACL resection model of rats. The oligonucleotide significantly decreased the production of inflammatory cytokines such as TNFα and IL-6, as well as catabolic proteases MMP-3, MMP-13, and ADMATS5, in vitro chondrocytes. Mechanistically, the decrease of MMP-13 by the oligonucleotide was reversed by inhibiting adenosine receptors A1 and A2A, indicating that its anabolic effects are mediated by these adenosine receptors. Additionally, the treatment of oligonucleotide significantly increased the phosphorylation of AMPK and the protein level of SIRT1.

Conclusion: The PLGA nanoparticles containing anti-inflammatory oligonucleotides demonstrated protective effects in surgically induced OA models, which were mediated by adenosine receptors A1 and A2A, along with their downstream AMPK-SIRT1 axis.

« Back to ACR Convergence 2024

ACR Meeting Abstracts - https://acrabstracts.org/abstract/adenosine-and-guanosine-based-oligonucleotide-attenuates-catabolic-phenotypes-in-chondrocytes-and-slows-progression-of-surgically-induced-osteoarthritis/