Self-Assembling Hydrogels of Naproxen-Conjugated Peptides for Osteoarthritis Treatment

<b>Rationale</b>: Osteoarthritis (OA), a highly prevalent chronic degenerative joint disease, lacks truly effective therapies. Current approaches are limited by systemic toxicity, short drug half-lives, and insufficient efficacy. To address this, we developed an innovative therapeutic approach integrating the pharmacological benefits of nonsteroidal anti-inflammatory drugs (NSAIDs) with the mechanical support and localized delivery advantages of hydrogels. <b>Methods</b>: Various naproxen-peptide conjugates are designed and synthesized. These candidates were screened based on self-assembly behavior, biocompatibility and cyclooxygenase-2 (COX-2) inhibition. NpxFFK underwent further studies including assessment of anti-inflammatory activities and mechanism of action <i>in vitro</i>. <i>In vivo</i> therapeutic efficacy was evaluated in OA rat model using footprinting assay, micro-CT imaging, MRI imaging, histological staining, and immunohistochemistry. The therapeutic mechanism is explored via RNA sequencing. <b>Results</b>: Among naproxen-peptide conjugates NpxFFX (X = R, H, K, E) tested, NpxFFK demonstrated superior anti-inflammatory efficacy. It self-assembled into a stable hydrogel, exhibiting enhanced retention within the joint cavity and providing sustained anti-inflammatory action. <i>In vitro</i> studies revealed that NpxFFK effectively inhibited COX-2 activity, consequently suppressing key inflammatory factors (IL-1β, IL-6, IL-1, and TNF-α). Furthermore, it reprogramed macrophage polarization from M1 toward M2 and promoted chondrocyte proliferation. <i>In vivo</i> experiments demonstrate the NpxFFK hydrogel significantly mitigated articular degradation in OA rats, outperforming clinical treatments (naproxen treatment or hyaluronic acid treatment), thereby validating its therapeutic potential for OA. <b>Conclusions</b>: By integrating NSAID pharmacology with self-assembling peptide hydrogel delivery platform, we present a multifunctional strategy that significantly improves upon current OA treatments, underscoring its promise for translational healthcare innovation in OA management.