Anti‐inflammatory Nanotherapy Targeting NF‐κB In Experimental Osteoarthritis
Authors: Yan Huimin , Duan Xin , Pan Hua , Sandell Linda , Wickline Samuel , Pham Christine 
Published: November 2023

Objective

Osteoarthritis (OA) is a progressive disease that causes significant pain and suffering and for which there are no disease‐modifying drugs. Therapeutic strategies for OA remain in their infancy as our understanding of the pathways governing early cartilage degeneration remained largely unexplored. Recent studies suggest that human OA is an inflammatory disease and this inflammation contributes to cartilage degeneration and joint destruction. The NF‐κB pathway is the central regulator of the inflammatory responses in OA synovium and chondrocytes. We posit that direct inhibition of NF‐κB suppresses inflammation and protects the joint from cartilage degeneration and subsequent OA development.

Methods

We employed a novel peptidic nanoparticle (NP) structure that features an amphipathic, cationic, cell penetrating peptide as an siRNA carrier that is stable in biological fluids and enables coordinated endosomal escape and release of siRNA into cytoplasm to rapidly engage the RISC complex and simultaneously suppress both canonical and noncanonical NF‐κB activities. The entire complex can be formed within as little as ten minutes by a simple mixing procedure that allows noncovalent, self‐assembly of cationic and anionic moieties into a ~55 nm nanocomplex. The self‐assembling nanoplatform injected into the affected joints achieves local gene silencing while avoiding undesirable systemic effects on physiological NF‐κB functions. We also used a newly developed rodent model that represents OA resulting from impact injury, which accounts for more than 20% of total joint replacements. This model allows for the study of early events and synovial inflammatory responses at specific time points after injury.

Results

Chondrocyte apoptosis, as evidenced by TUNEL staining, occurred rapidly upon injury (within 12 h) in this model at the site of impact. There was also stimulation of cellular responses in the chondrocytes at and around the impact injury site, including activation of the NF‐κB signaling pathway and modulation of autophagy. Intra‐articular administration of NF‐κB p65 siRNA nanoparticles immediately after impact injury significantly attenuated p65 phosphorylation and chondrocyte apoptosis at 24 h. Furthermore, intra‐articular administration of the combined NF‐κB canonical p65 and non‐canonical p100 siRNA nanoparticles significantly suppressed p65/p100 phosphorylation, chondrocyte apoptosis, and synovial proliferation at day 5 post impact injury. Autophagy is a key cellular pathway in the maintenance of cartilage homeostasis. Defective autophagy has been shown to contribute to chondrocyte death and cartilage degeneration in OA. Our data suggest that NF‐κB siRNA nanotherapy partially preserved cartilage integrity by protecting against the impact‐injury‐induced downmodulation of autophagy in chondrocytes.

Conclusion

These results provide proof‐of‐concept that intra‐articular delivery of peptide‐NF‐κB siRNA nanotherapy protects against early chondrocyte apoptosis and autophagy downmodulation while suppressing synovial proliferation induced by impact injury, all of which ultimately may serve to retard experimental OA progression.

Support or Funding Information

NIH (HL113392, CA100623, CA154737, HL094470, AR056468, NS073457, CA136398) and The American Heart Association (0835426N and 11IRG5690011)