Integrating metabolomics and network pharmacology to study the mechanism of Er-Xian Decoction in improving intervertebral disc degeneration.

Background: Intervertebral disc degeneration (IDD) is the progressive deterioration of the structure and function of an intervertebral disc (IVD), which manifests as excessive catabolism of the IVD extracellular matrix, which may lead to the gradual loss of IVD proteoglycans and water, thus altering the IVD composition and eventually leading to degeneration. As a traditional Chinese medicine, Er-Xian decoction (EXD) can balance the body's yin and yang, tonify the liver and kidney, invigorate blood circulation, and prevent blood stasis. Pharmacological research has shown that EXD regulates antioxidant and endocrine metabolism, maintains immune balance, and improves microcirculation.

Objective: To clarify the efficacy of EXD on treating IDD.

Methods: Serum was collected from model IDD rabbits treated with EXD for metabolomics analysis, and its mechanism of action was predicted on the basis of the metabolomics and network pharmacology data. Nucleus pulposus cells (NPCs) were induced with IL-1β to build an in vitro IDD model, and EXD was administered along with an inhibitor. All groups of cells were subjected to CCK-8 assays, ELISA and flow cytometry, immunohistochemistry, Western blot, and immunofluorescence staining analyses to explore how EXD protects NPCs and the underlying mechanism.

Results: EXD reduced inflammatory processes, restored IVD height, and alleviated IDD in rabbits. Integrated metabolomics and network pharmacology analyses revealed that EXD exerts its therapeutic effects on IDD primarily via the mTOR and HIF-1 signalling pathways, and the active components of EXD, including anhydroicaritin, β-sitosterol, kaempferol, quercetin, and stigmasterol, bound strongly to pivotal targets within these pathways. Moreover, EXD reduced the inflammatory factor levels, inhibited NPC apoptosis, and upregulated the key proteins p-mTOR, HIF-1α, and p-AKT. Conversely, the HIF-1 inhibitor BAY872243 increased the inflammatory factor levels and led to NPC deterioration.

Conclusions: EXD regulates disc cell metabolism and inflammatory responses by modulating the mTOR and HIF-1 signalling pathways, thereby slowing or reversing IDD.