Salidroside suppresses keloid fibroblast activation via SPHK1 as a downstream effector: Bioinformatics and in vitro experimental evidence

Background Keloid disease is a fibroproliferative disorder with limited effective treatments. Salidroside has garnered significant attention for its diverse pharmacological properties. Objective This study aimed to identify the molecular mediators through which salidroside inhibits fibrotic phenotypes in keloid fibroblasts (KFs) in vitro . Methods Putative salidroside targets were retrieved from SwissTargetPrediction, HERB 2.0, and Comparative Toxicogenomics Database (CTD), and intersected with keloid-associated genes from GeneCards and differentially expressed genes (DEGs) from the GSE44270 dataset. Molecular docking was performed to assess the potential binding between salidroside and sphingosine kinase type 1 (SPHK1). Functional assays (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 5-ethynyl-2’-deoxyuridine (EdU), flow cytometry, Transwell, wound healing, immunoblotting, and enzyme-linked immunosorbent assay (ELISA)) were performed in human immortalized KFs following salidroside treatment, SPHK1 knockdown, or salidroside treatment along with SPHK1 re-expression. Results Intersection analysis identified SPHK1 as a previously unreported candidate mediator of salidroside activity. SPHK1 was upregulated in KFs compared with human skin fibroblasts (HSF, 2.48 ± 0.15 vs. 1.00 ± 0.10, P < 0.001). Molecular docking yielded a calculated binding energy of −7.7 kcal/mol, with predicted hydrogen bonds at Alanine (ALA)-60, Arginine (ARG)-56, Serine (SER)-79, and SER-112. Salidroside treatment or SPHK1 knockdown suppressed KF proliferation ( P < 0.05), migration ( P < 0.01), invasion ( P < 0.05), fibrotic protein expression ( P < 0.001), and sphingosine‑1‑phosphate (S1 P) production ( P < 0.01). Salidroside downregulated SPHK1 in KFs (1.00 ± 0.14–0.23 ± 0.11, P < 0.001). SPHK1 re-expression reversed salidroside-induced suppression of these fibrotic phenotypes ( P < 0.05). Conclusion This study provides preliminary in vitro evidence that salidroside suppresses fibrotic activation in KFs through a mechanism involving SPHK1 as a downstream effector. These findings are consistent with the interpretation that SPHK1 is necessary for this effect, but do not confirm direct physical targeting.