Oridonin alleviates the inhibitory effect of lipopolysaccharide on the proliferation and osteogenic potential of periodontal ligament stem cells by inhibiting endoplasmic reticulum stress and NF-κB/NLRP3 inflammasome signaling

GNAI3 mediated by Lin28A regulates lipopolysaccharide-induced inflammation and osteogenic differentiation in periodontal stem cells by mediating the NF-κB/NLRP3 inflammasome pathway

OBJECTIVES

The aim of this study was to investigate the regulatory role of G protein subunit alpha i3 (GNAI3) in periodontitis.

DESIGN

Following the induction of human periodontal ligament stem cells (hPDLSCs) with lipopolysaccharide (LPS), the mRNA and protein expressions of GNAI3 and Lin28A were detected by real-time quantitative polymerase chain reaction (RT-qPCR) and western blot. The transfection efficiency of Oe-GNAI3 and sh-Lin28A was examined by virtue of RT-qPCR and western blot. With the application of ELISA and flow cytometry, the releases of inflammatory cytokines and cell apoptosis were appraised. Alkaline phosphatase (ALP) staining and alizarin red S (ARS) staining were conducted to evaluate osteogenic differentiation. Next, the binding ability of Lin28A with GNAI3 mRNA was estimated by radioimmunoprecipitation (RIP) assay while the stability of GNAI3 mRNA was assessed utilizing RT-qPCR. Western blot was employed for the measurement of inflammation-, apoptosis- and nuclear factor-kappaB (NF-κB)/NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome pathway-related proteins and osteogenic markers.

RESULTS

The expression of GNAI3 was down-regulated in LPS-induced hPDLSCs. After the transfection with Oe-GNAI3, the inflammation and apoptosis in LPS-induced hPDLSCs were inhibited while osteogenic differentiation was promoted. Moreover, Lin28A could stabilize GNAI3 mRNA and Lin28A knockdown significantly reduced GNAI3 expression. Further experiments verified that the inhibitory effects of GNAI3 overexpression on LPS-induced cellular inflammation and cell apoptosis as well as the promotive effects on osteogenic differentiation in hPDLSCs were all partially counteracted by Lin28A depletion, which may possibly be mediated via the regulation of the NF-κB/NLRP3 inflammasome pathway.

CONCLUSION

GNAI3 that mediated by Lin28A regulates the inflammation and osteogenic differentiation in LPS-induced hPDLSCs by mediating the NF-κB/NLRP3 inflammasome pathway.

Quercetin, Main Active Ingredient of Moutan Cortex, Alleviates Chronic Orofacial Pain via Block of Voltage-Gated Sodium Channel

BACKGROUND

Chronic orofacial pain (COP) therapy is challenging, as current medical treatments are extremely lacking. Moutan Cortex (MC) is a traditional Chinese medicine herb widely used for chronic inflammatory diseases. However, the mechanism behind MC in COP therapy has not been well-established. The purpose of this study was to identify the active ingredients of MC and their specific underlying mechanisms in COP treatment.

METHODS

In this study, the main active ingredients and compound-target network of MC in COP therapy were identified through network pharmacology and bioinformatics analysis. Adult male Sprague-Dawley rats received oral mucosa lipopolysaccharide (LPS) injection to induce COP. Pain behaviors were evaluated by orofacial mechanical nociceptive assessment after intraganglionar injection. In vitro inflammatory cytokines in LPS-pretreated human periodontal ligament stem cells (hPDLSCs) and rat primary cultural trigeminal ganglion (TG) neurons were quantified by real-time quantitative polymerase chain reaction (RT-qPCR). Schrödinger software was used to verify the molecular docking of quercetin and critical targets. Whole-cell recording electrophysiology was used to evaluate the effect of quercetin on voltage-gated sodium (Na v ) channel in rat TG neurons.

RESULTS

The assembled compound-target network consisted of 4 compounds and 46 targets. As 1 of the active components of MC correlated with most related targets, quercetin alleviated mechanical allodynia in LPS-induced rat model of COP (mechanical allodynia threshold median [interquartile range (IQR) 0.5 hours after drug administration: vehicle 1.3 [0.6-2.0] g vs quercetin 7.0 [6.0-8.5] g, P = .002). Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that immune response and membrane functions play essential roles in MC-COP therapy. Five of the related targets were identified as core targets by protein-protein interaction analysis. Quercetin exerted an analgesic effect, possibly through blocking Na v channel in TG sensory neurons (peak current density median [IQR]: LPS -850.2 [-983.6 to -660.7] mV vs LPS + quercetin -589.6 [-711.0 to -147.8] mV, P = .006) while downregulating the expression level of proinflammatory cytokines-FOS (normalized messenger RNA [mRNA] level mean ± standard error of mean [SEM]: LPS [2. 22 ± 0.33] vs LPS + quercetin [1. 33 ± 0.14], P = .034) and TNF-α (normalized mRNA level mean ± SEM: LPS [8. 93 ± 0.78] vs LPS + quercetin [3. 77 ± 0.49], P < .0001).

CONCLUSIONS

Identifying Na v as the molecular target of quercetin clarifies the analgesic mechanism of MC, and provides ideas for the development of novel selective and efficient chronic pain relievers.

Oridonin Attenuates Thioacetamide-Induced Osteoclastogenesis Through MAPK/NF-κB Pathway and Thioacetamide-Inhibited Osteoblastogenesis Through BMP-2/RUNX2 Pathway

Osteoporosis, an age-related metabolic bone disease, is mainly caused by an imbalance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption. At present, there are many osteoporosis drugs that can promote bone formation or inhibit bone resorption. However, there were few therapeutic drugs that can simultaneously promote bone formation and inhibit bone resorption. Oridonin (ORI), a tetracyclic diterpenoid compound isolated from Rabdosia rubescens, has been proved to have anti-inflammatory, anti-tumor effects. However, little is known about the osteoprotective effect of oridonin. Thioacetamide (TAA) is a common organic compound with significant hepatotoxicity. Recent studies have found that there was a certain association between TAA and bone injury. In this work, we investigated the effect and mechanism of ORI on TAA-induced osteoclastogenesis and inhibition of osteoblast differentiation. The results showed that TAA could promote the osteoclastogenesis of RAW264.7 by promoting the MAPK/NF-κB pathway, and also promoted p65 nuclear translocation and activated intracellular ROS generation, and ORI can inhibit these effects to inhibit TAA-induced osteoclastogenesis. Moreover, ORI can also promote the osteogenic differentiation pathway and inhibit adipogenic differentiation of BMSCs to promote bone formation. In conclusion, our results revealed that ORI, as a potential therapeutic drug for osteoporosis, could protect against TAA-induced bone loss and TAA-inhibited bone formation.