Gubi Decoction Ameliorates Porous Cartilage Endplate in an Intervertebral Disc Degeneration Model Mouse Through Inhibition of NF-κB Activity and Pyroptosis.

Background: Intervertebral disc (IVD) degeneration (IVDD) is highly prevalent among the elderly population and stands as a leading cause of low back pain. Our prior studies have highlighted the therapeutic potential of Gubi decoction (GBD) in alleviating knee osteoarthritis, however, but the specific mechanism of GBD in treating IVDD is not clear. Objective: To ascertain the clear mechanism of GBD for enhancing its therapeutic efficacy in treating lVDD, through comparison of its effects across different doses of GBD and clinical positive control drugs using a mouse IVDD model. Methods: In this study, 8-week-old male mice were treated with lumbar spine instability (LSI) surgery to construct IVDD model mice. From day 3 post-LSI surgery, mice in the loxoprofen sodium tablets (LST), GBD-L, GBD-M and GBD-H groups were gavage administration with LST (23.1 mg/kg) and GBD (6.1, 12.2 and 24.4 g/kg body weight, respectively) 5 times a week for 4 and 8 weeks separately. After 8 weeks of LSI modeling, the therapeutic efficacy on IVDD was evaluated through changes in lumbar spine function, histopathological morphology, extracellular matrix (ECM) metabolism, nucleus pulposus (NP) cell viability, and cartilage endplate (CEP) cell pyroptosis; at 4 weeks after modeling, the activation of NF-κB signaling was detected. Results: GBD can attenuate the progression of IVDD in mice, resulting in substantially increases disc height index (DHI) and NP matrix, reduced the degree of annulus fibrosus (AF) tear and the formation of cavity in CEP. In parallel, GBD significantly improved the matrix metabolism-related indexes of IVD at 8 weeks after modeling. Mechanically, GBD inhibited the expression of pyroptosis-related indicators NOD-like receptor thermal protein-domain associated protein 3 (NLRP3), cysteinyl aspartate specific-proteinase-1 (CASPASE1), gasdermin D (GSDMD), interleukin-1β (IL-1β) and interleukin-18 (IL-18) in CEP. Furthermore, GBD suppressed nuclear translocation of P65 protein, and decreased the amount of p-I-κB in CEP at 4 weeks after modeling. Conclusion: In summary, GBD can effectively inhibit the activation of NF-κB signaling and pyroptosis of ECP, relieve the porosity of ECP, and then delay the IVDD process. GBD may serve as a potential therapeutic agent for IVDD treatment.