Salvianolic acid A modulates α-Ketoisovaleric acid metabolism to inhibit human cartilage endplate cells apoptosis under mechanical tensile stress

Intervertebral disc degeneration (IDD) represents a key contributor to chronic back pain and cartilage endplate cell (CEPCs) are mechanically sensitive. Salvianolic acid A (SAA), a polyphenolic compound of traditional Chinese medicine Salvia miltiorrhiza, have protective potential on IDD in our previous study. This study was purposed to clarify the effect of SAA on the metabolic profiles of CEPCs under mechanical tension and its underlying mechanisms. CEPCs were isolated from human lumbar discs and subjected to mechanical tensile loading (10% strain, 1 Hz, 24 h), with or without 10µM SAA pretreatment. The CCK-8 (for viability) and flow cytometry assays (for apoptosis) of CEPCs were detected. Non-targeted metabolomics was performed using UHPLC-Q-TOF-MS, followed by KEGG pathway enrichment analysis. Virtual molecular docking was used to screen the core targets of SAA and IDD intersected proteins. Realtime PCR and immunofluorescence were conducted. SAA enhanced cell viability and reduced apoptosis of CEPCs under mechanical tensile loading. The differentially expressed metabolite α-ketoisovaleric acid was screened. SAA upregulated collagen II, GSK-3β and downregulated BMP2, MMP3, Wnt3α, collage I expression. In addition, SAA also downregulated miR-940 exosome expression. SAA regulated α-ketoisovaleric acid and inhibited stress-loaded CEPCs apoptosis possibly by regulating miR-940 related signaling pathway protein.