Basic Study
WANG Feifei, ZHENG Chengju, CHEN Zhiyun, LIU Ting, WANG Yu
Objective To investigate the molecular regulatory mechanism of hypoxia-inducible factor-1α (HIF-1α) in mechanical stress-induced inflammatory cytokine expression in human periodontal ligament cells (hPDLCs), providing a theoretical basis and potential therapeutic target for inflammatory control during orthodontic treatment. Methods This study was approved by the Institutional Ethics Committee. Primary human periodontal ligament cells (hPDLCs) were isolated and cultured in vitro. Self-renewal capacity was confirmed via colony-forming assays, while osteogenic and adipogenic differentiation potential was evaluated via Alizarin Red S staining, alkaline phosphatase (ALP) activity assays, and Oil Red O staining. An in vitro compressive force stimulation model (1.5 g/cm2, 12 h) was established to compare inflammatory cytokine expression of hPDLCs—interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and HIF-1α—between the Control group (no mechanical stimulation) and the Force group (1.5 g/cm2, 12 h) using quantitative real-time PCR (qRT-PCR), Western blot, and immunofluorescence (IF) staining. Mechanically induced HIF-1α-regulated gene expression changes were analyzed through transcriptomic sequencing. To explore pharmacological inhibition, the small-molecule HIF-1α inhibitor LW-6 was applied at varying concentrations (10 μmol/L, 30 μmol/L, 50 μmol/L) to optimize the treatment dose. Subsequently, qRT-PCR, Western blot, and IF staining were conducted to evaluate inflammatory cytokine of hPDLCs and HIF-1α expression in three groups: Control (no force), Force (1.5 g/cm2, 12 h), and Force+LW6 (1.5 g/cm2, 12 h + 30 μmol/L LW-6). Results Primary hPDLCs demonstrated self-renewal capacity along with osteogenic and adipogenic differentiation potential. Compared to the Control group, the Force group exhibited significantly increased mRNA and protein expression levels of inflammatory cytokines IL-1β, IL-6, and TNF-α, along with enhanced fluorescence intensity of IL-1β and TNF-α. Transcriptomic analysis revealed that mechanical compressive force activated the HIF-1 signaling pathway, which subsequently mediated inflammatory responses and bone remodeling processes in hPDLCs. Furthermore, the mRNA and protein levels of HIF-1α were considerably elevated in the Force group compared to the Control group. Treatment with LW-6 (10, 30, or 50 μmol/L) effectively suppressed HIF-1α expression, with 30 μmol/L LW-6 identified as the optimal concentration for intervention. In subsequent experiments, the Force group showed significant upregulation in mRNA/protein expression of IL-1β, IL-6, and TNF-α compared to the Control group, as well as intensified HIF-1α, IL-1β, and TNF-α fluorescence signals. Conversely, the Force+LW6 group (mechanical force + 30 μmol/L LW-6) exhibited a notable reduction in inflammatory cytokine expression levels and a weakening of HIF-1α, IL-1β, and TNF-α fluorescence signals compared to the Force group. Conclusion HIF-1α potentiates mechanical stress-induced inflammatory responses in hPDLCs and may serve as a promising therapeutic target for mitigating orthodontic-associated periodontal inflammation.