Periplocin targets LRP4 to regulate metabolic homeostasis and anti-inflammation for the treatment of IVDD

Background: Intervertebral disc degeneration (IVDD) is characterized by deteriorating intervertebral discs, leading primarily to low back pain and leg pain. Most current treatments for IVDD primarily address symptoms without targeting the underlying degenerative process. Moreover, tumor necrosis factor-α (TNF-α)-mediated inflammation and degradation of the nucleus pulposus (NP) extracellular matrix (ECM) influence this pathological process. Periplocin, a cardiotonic steroid extracted from periplocin forrestii, has demonstrated a wide range of medical benefits, including cardiotonic, Anticancer, anti-inflammatory, and wound healing properties. Nevertheless, the effects of periplocin on IVDD remain unexplored.

Objective: Our study explores the mechanism of action and the potential target of periplocin in mitigating IVDD pathology.

Methods: Rat models of IVDD were established using acupuncture, and the affected discs underwent analysis via Safranin O-Fast Green (S-O) and Hematoxylin and Eosin (H&E) staining. Nucleus pulposus cells (NPCs) were harvested from IVDD patients and experimental Animals for examination. A variety of techniques, including Western blot analysis, quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) assay, immunofluorescence staining, Alcian Blue staining and Immunohistochemistry (IHC) staining, were utilized to evaluate inflammation-related proteins, mRNAs and the ECM metabolism. In order to ascertain the potential protein targets of periplocin, the binding site of periplocin to LRP4 was elucidated through the utilisation of molecular docking experiments. Subsequently, the expression of low-density lipoprotein receptor-related protein 4 (LRP4) in NPCs was modified through the use of small interfering RNA (siRNA) knockdown and overexpression vectors, which were employed for the purposes of target validation.

Results: We conclude from the present study that periplocin alleviates the progression of IVDD mainly through the following aspects: periplocin inhibits TNF-α-induced inflammatory; periplocin reduces matrix degradation; periplocin promotes matrix anabolism and regulates metabolic homeostasis. Moreover, the present study demonstrates that LRP4 is involved as a potential target in the multiple pathways mentioned above to protect the intervertebral disc.

Conclusion: Our research suggests that periplocin may serve as a promising treatment for IVDD, offering anti-inflammatory benefits, preventing ECM degradation, and promoting ECM anabolism.

Intervertebral disc degeneration; LRP4; Molecular docking; Periplocin; TNF-α; inflammation.