Differential Transcriptomic and Adhesion Responses of Human Periodontal Ligament Cells to Cyclic and Static Hydrostatic Pressure

Periodontal ligament (PDL) cells are continuously exposed to in vivo dynamic mechanical forces; however, how distinct temporal patterns of hydrostatic pressure (HP) regulate their mechanobiological responses remains unclear. This study aimed to elucidate how static and cyclic HP differentially regulate mechanotransduction in human PDL cells. Human PDL cells were exposed to static or cyclic HP using a custom-designed stimulation system. Global transcriptional responses were analyzed using RNA sequencing, followed by gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses. Focal adhesion (FA) and signaling were further examined using immunofluorescence, protein expression analysis, and targeted gene knockdown. Cyclic HP induced substantially broader transcriptional remodeling than static HP, with 2665 upregulated and 2749 downregulated genes. Enrichment analyses consistently identified the FA and cytoskeletal pathways as the principal mechanosensitive networks. Cyclic HP selectively upregulated FA-associated genes, including integrin-linked kinase (ILK), paxillin (PXN), tensin 1 (TNS1), four-and-a-half LIM domains 3 (FHL3), and YWHAZ, while downregulating integrin subunit-encoding genes, ITGA4 and ITGB8, indicating the remodeling of adhesion composition. Consistently, cyclic HP increased FA count, ILK expression, and Akt phosphorylation than static HP. ILK silencing significantly attenuated HP-induced Akt activation and FA formation. These results suggest that cyclic HP is associated with enhanced ILK-related Akt signaling and alterations in FA architecture in PDL cells, temporally distinct mechanotransductive response. This study provides molecular insight into how dynamic mechanical loading may influence periodontal tissue adaptation and remodeling.