Low‐intensity pulsed ultrasound promotes bone morphogenic protein 9‐induced osteogenesis and suppresses inhibitory effects of inflammatory cytokines on cellular responses via Rho‐associated kinase 1 in human periodontal ligament fibroblasts

Abstract

Periodontal ligament fibroblasts (PDLFs) have osteogenic capacity, producing bone matrix proteins. Application of bone morphogenic proteins (BMPs) to PDLFs is a promising approach for periodontal regeneration. However, in chronic bone metabolic disorders, such as periodontitis, proper control of accompanying inflammation is essential for optimizing the effects of BMPs on PDLFs. We have previously shown that low‐intensity pulsed ultrasound (LIPUS), a medical technology that induces mechanical stress using sound waves, significantly promotes osteogenesis in mesenchymal stem cells. Here, we demonstrate that LIPUS promotes the BMP9‐induced osteogenic differentiation of PDLFs. In contrast, BMP2‐induced osteogenic differentiation was not altered by LIPUS, probably due to the LIPUS‐induced secretion of Noggin, a BMP2 antagonist, from PDLFs. To examine if LIPUS affects inflammatory responses of PDLFs to lipopolysaccharide (LPS) derived from Porphyromonas gingivalis (LPS‐PG), we also simultaneously treated PDLFs with LIPUS and LPS‐PG. Treatment with LIPUS significantly inhibited the phosphorylation of ERKs, TANK‐binding kinase 1, and interferon regulatory factor 3 in LPS‐PG‐stimulated PDLFs, in addition to inhibiting the degradation of IκB. Furthermore, LIPUS treatment reduced messenger RNA (mRNA) expression of interleukin‐1alpha (IL‐1alpha), IL‐1beta, IL‐6, IL‐8, C‐C motif chemokine ligand 2, C‐X‐C motif chemokine ligand 1 (CXCL1), CXCL10 and receptor activator of nuclear factor kappa‐B ligand, and also diminished IL‐1ß and tumor necrosis factor a (TNFa)‐induced inflammatory reactions. Phosphorylation of Rho‐associated kinase 1 (ROCK1) was induced by LIPUS, while ROCK1‐specific inhibitor prevented the promotive effects of LIPUS on p38 phosphorylation, mRNA expression of CXCL1 and Noggin, and osteogenesis. The suppressive effects of LIPUS on LPS‐PG‐stimulated inflammatory reactions were also prevented by ROCK1 inhibition. Moreover, LIPUS treatment blocked inhibitory effects of LPS‐PG and IL‐1ß on osteogenesis. These results indicate that LIPUS suppresses inflammatory effects of LPS‐PG, IL‐1ß, and TNFa and also promotes BMP9‐induced osteogenesis through ROCK1 in PDLFs.

Low‐intensity pulsed ultrasound promotes the formation of periodontal ligament stem cell sheets and ectopic periodontal tissue regeneration

“…Low‐intensity pulsed ultrasound (LIPUS) is a non‐invasive ultrasound stimulus that could enhance fracture and non‐union bone healing 21 . It could enhance tissue repair and regeneration by inducing osteogenic differentiation of cells, producing more calcium deposits, and promoting the secretion of cytokines and ECM 22‐24 . Previous studies by our research group have demonstrated that LIPUS can attenuate lipopolysaccharide‐induced inflammation of PDLC 25 and improve its osteogenic differentiation, 26,27 which has great significance for regenerative treatment of periodontitis.…”

“…21 It could enhance tissue repair and regeneration by inducing osteogenic differentiation of cells, producing more calcium deposits, and promoting the secretion of cytokines and ECM. [22][23][24] Previous studies by our research group have demonstrated that LIPUS can attenuate lipopolysaccharide-induced inflammation of PDLC 25 and improve its osteogenic differentiation, 26,27 which has great significance for regenerative treatment of periodontitis. Since LIPUS affects the synthesis of ECM proteins in cells and bone tissue repair, we hypothesized that LIPUS can stimulate the formation of hPDLSC sheets (hPDLSCSs) and affect their osteogenic differentiation, further improving periodontal tissue regeneration.…”

The Effect of Different Dietary and Therapeutic Solutions on the Color Stability of Resin-Matrix Composites Used in Dentistry: An In Vitro Study

“…An acidic environment in the oral cavity could also lead to an increased chemical reactivity of the restorative materials; this could be caused by the uptake of acidic beverages or inflammatory reactions in the oral cavity (i.e., periodontitis) [ 12 , 13 ]. Several studies have shown that subjects with periodontitis have significantly higher salivary levels of cytokines, acidic substances, and reactive oxidative stress molecules [ 12 , 13 , 34 , 35 , 36 ].…”

Effects of collimated and focused low-intensity pulsed ultrasound stimulation on the mandible repair in rabbits

“…LIPUS treatment is an emerging physical therapy for the bone, nerve, and muscle disorders (15). Available studies have confirmed that it can suppress inflammation, promote osteogenesis and facilitate the ossification of hypertrophic chondrocytes (16,17). This study investigated and compared the effects of LICU and LIFU on the bone formation in rabbits.…”