Periostin-αVβ5 Integrin Enhances Inflammatory Cytokine Under Mechanical Stress in Human Periodontal Ligament Cells

Objectives: Periostin signaling pathway are known to involve in mechanotransduction of Human Periodontal Ligament Cells (hPDLC). It has been observed that mechanical stress influences the expression of various inflammatory cytokines, including IFN-γ. However, the detailed mechanism remains unclear. This study aims to investigate the force-induced periostin-integrin signaling pathway in hPDLC, leading to the expression of inflammatory cytokine.
Methods: hPDLC were cultured, and applied with 0 (control), 0.5 and 5 dyn/cm² of shear force for 3 hours (n=3). Cell membrane permeabilized and a non-permeabilized group of hPDLC were used to localize periostin through an immunofluorescence assay. To determine the periostin-related pathway, siRNA of periostin was used. Additionally, two substances were used to inhibit integrin activity: Cilengitide, which is α_Vβ₅ and α_Vβ₃ integrin inhibitor, and siRNA of αVβ5 integrin. The amounts of IFN-γ gene and protein expressions were assessed using qRT-PCR and ELISA at 24 hours. The results were analyzed with one-way ANOVA.
Results: Shear force stimulation led to localized periostin accumulation in the intracellular matrix, as observed by immunofluorescent assay. IFN-γ gene expression in hPDLC significantly increased in a magnitude-dependent manner after shear force stimulation. This inductive effect was decreased after knocking down periostin. Additionally, inhibition of periostin receptors with Cilengitide attenuated the enhancement of periostin on shear force-induced IFN-γ expression by qRT-PCR and ELISA. Accordingly, knockdown of αVβ5 integrin abolished the enhancement of shear force-induced IFN-γ expression.
Conclusions: The results of this study reveal the requirement of intracellular periostin-αVβ5 integrin signaling in force-induced IFN-γ expression in hPDLC. This information largely supports that periostin-integrin is crucial in maintaining periodontium homeostasis, thus increasing the understanding of the reciprocal role of the intracellular matrix and shear force on periodontium homeostasis. This new finding could be used clinically to target periostin-αVβ5 integrin to promote periodontal tissue remodeling and reduce inflammation especially in periodontitic patient.