Bushenhuoxue Formula Protects Against Lumbar Facet Joint Osteoarthritis via Acting on TDP-43-Mediated Pyroptosis to Loose Caspase-11/NLRP3 Interaction.

BACKGROUND

Facet joint osteoarthritis (FJOA) is a serious facet joint cartilage degeneration disorder, which is an important cause of low back pain and disability. Bushenhuoxue formula (BSHXF), a traditional Chinese herbal compound, has been demonstrated to exhibit the ability to improve osteoarthritis. This study aimed to uncover the therapeutic effect and potential mechanism of BSHXF in FJOA.

METHODS

FJOA rats were treated with BSHXF. Histological staining, immunohistochemistry, TUNEL staining, and flow cytometry were performed for detecting pathological damage, molecule expressions in articular cartilage, chondrocyte apoptosis, and pyroptosis, respectively. Interleukin (IL)-18 and IL-1β levels were quantified with enzyme-linked immunosorbent assay. RT-qPCR and Western blot were carried out for evaluating mRNA and protein expressions. Immunofluorescence and coimmunoprecipitation were used to study the colocalization and interaction between Caspase-11 and Nod-like receptor protein-3 (NLRP3) in chondrocytes.

RESULTS

In FJOA rats, BSHXF attenuated articular cartilage pathological damage. Specifically, BSHXF inhibited matrix degradation, as indicated by increasing collagen II and decreasing matrix metalloproteinase 13. BSHXF inhibited articular chondrocyte apoptosis and promoted chondrocyte proliferation. BSHXF decreased Caspase-1 and NLRP3, reduced the rate of Caspase-1/propidium iodide-stained chondrocytes, and inhibited inflammatory cytokines, indicating the attenuated articular chondrocyte pyroptosis. BSHXF downregulated Caspase-11, loosened the interaction between NLRP3 and Caspase-11, as well as upregulated transactive response DNA-binding protein 43 (TDP-43) in FJOA rats. Additionally, in H2O2-exposed chondrocytes, TDP-43 overexpression decreased TLR4, p-IκBα, NF-κB P65, and Caspase-11 and declined the co-localization of Caspase-11 and NLRP3. Importantly, TDP-43 knockdown reversed BSHXF-mediated protective effects in FJOA rats.

CONCLUSION

BSHXF inhibited chondrocyte pyroptosis by increasing TDP-43 to protect against FJOA via loosening the interaction of Caspase-11 and NLRP3, which may provide a fundamental basis for treating FJOA cartilage damage.