Targeting EZH2 Ameliorates the LPS-Inhibited PDLSC Osteogenesis via Wnt/β-Catenin Pathway

DNMT3A transcriptionally downregulated by KLF5 alleviates LPS-induced inflammatory response and promotes osteogenic differentiation in hPDLSCs

BACKGROUND AND OBJECTIVE

Periodontitis is an inflammatory disease typically characterized by the destruction of periodontal tissues and complicated etiology. DNA methyltransferase 3A (DNMT3A) has been implicated in possessing pro-inflammatory properties. This study sought to explore the role of DNMT3A in periodontitis and its relevant mechanism.

METHODOLOGY

Lipopolysaccharide (LPS) was used to induce inflammation in human periodontal ligament stem cells (hPDLSCs). DNMT3A and KLF5 expressions were detected using RT-qPCR and western blot. The levels of inflammatory cytokines and inflammation-related proteins were detected using ELISA and western blot. NF-κB p65 expression was detected using immunofluorescence (IF) assay, while osteogenic differentiation was assessed using ALP assay and ARS staining. Western blot was used to measure the protein contents associated with osteogenic differentiation. DNMT3A activity was detected using luciferase report assay and chromatin immunoprecipitation (ChIP) was used to verify the interaction between KLF5 and DNMT3A.

RESULTS

DNMT3A expression increased in LPS-induced hPDLSCs. Silencing DNMT3A suppressed the LPS-induced inflammation in hPDLSCs, while promoting osteogenic differentiation. It was also found that transcriptional factor KLF5 could bind to DNMT3A promoters and regulate DNMT3A expression. Rescue experiments showed that KLF5 interference partially counteracted the inhibitory impacts of DNMT3A deficiency on inflammation and the promotive effects on osteogenic differentiation in LPS-induced hPDLSCs.

CONCLUSION

DNMT3A, when transcriptionally downregulated by KLF5, could alleviate LPS-challenged inflammatory responses and facilitate osteogenic differentiation in hPDLSCs.

PGC-1α inhibits NLRP3 signaling through transcriptional activation of POP1 to alleviate inflammation and strengthen osteogenic differentiation of lipopolysaccharide-induced human periodontal stem cells

Periodontitis is a chronic infectious disease that affects the oral health of adults. Periodontal stem cells (PDLSCs) have good self-renewal and multipotential differentiation abilities to maintain the integrity of periodontal support structure and repair defects. This study aimed to elucidate the role of peroxisome proliferator activated receptor-γ co-activator 1-α (PGC-1α) in lipopolysaccharide (LPS)-induced PDLSCs and the underlying mechanisms related to predicated that pyrin domain (PYD)-only protein 1 (POP1). Notably downregulated PGC-1α and POP1 expression was observed in LPS-induced PDLSCs. PGC-1α or POP1 overexpression significantly reduced the inflammation and enhanced the osteogenic differentiation of LPS-treated PDLSCs. Particularly, PGC-1 bound to POP1 promoter region and upregulated POP1 expression. Moreover, POP1 knockdown ameliorated the impacts of PGC-1α overexpression on the inflammation and osteogenic differentiation in LPS-induced PDLSCs. Besides, PGC-1α inactivated NLRP3 signaling in LPS-treated PDLSCs, which was reversed by POP1 knockdown. Taken together, PGC-1α inhibits NLRP3 signaling through transcriptional activation of POP1, thereby alleviating inflammation and strengthening osteogenic differentiation of LPS-induced PDLSCs.

Omentin-1 attenuates lipopolysaccharide-induced inflammation and osteogenic differentiation in periodontal ligament stem cells and reduces M1 macrophages polarization through repressing endoplasmic reticulum stress

Periodontitis is featured as the periodontium's pathologic destruction caused by the host's overwhelmed inflammation. Omentin-1 has been reported to be aberrantly downregulated in patients with periodontitis, but the specific regulation of Omentin-1 during the pathogenesis of periodontitis remains unclear. In this study, human periodontal ligament stem cells (hPDLSCs) were stimulated by lipopolysaccharide (LPS) from Porphyromonas gingivalis to establish an in vitro inflammatory periodontitis model. hPDLSCs were treated with recombinant human Omentin-1 (250, 500 and 750 ng/mL) for 3 h before LPS stimulation. Results revealed that Omentin-1 significantly inhibited LPS-induced inflammation in hPDLSCs through reducing the production of proinflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6) and downregulating the expression of Cox2 and iNOS. Meanwhile, Omentin-1 significantly enhanced alkaline phosphatase (ALP) activity and Alizarin red-stained area, accompanied by increasing expression osteogenic markers BMP2, OCN and Runx2, confirming that Omentin-1 restores osteogenic differentiation in LPS-induced hPDLSCs. In addition, the conditioned medium (CM) from LPS-induced hPDLSCs was harvested to culture macrophages, which resulted in macrophage polarization towards M1, while CM from Omentin-1-treated hPDLSCs reduced M1 macrophages polarization and elevated M2 polarization. Furthermore, Omentin-1 also inhibited LPS-triggered endoplasmic reticulum (ER) stress in hPDLSCs, and additional treatment of the ER stress activator tunicamycin (TM) partially reversed the functions of Omentin-1 on inflammation, osteogenic differentiation and macrophages polarization. In summary, Omentin-1 exerted a protective role against periodontitis through inhibiting inflammation and enhancing osteogenic differentiation of hPDLSCs, providing a novelty treatment option for periodontitis.

Exosomes miR-92a-3p from human exfoliated deciduous teeth inhibits periodontitis progression via the KLF4/PI3K/AKT pathway

BACKGROUND

Periodontitis is a chronic inflammatory disease mediated by dysbiosis of the oral microflora, resulting in the destruction of periodontal tissue. Increasing evidence suggested that mesenchymal stem cell (MSCs) and exosomes derived from MSCs play a critical role in periodontal tissue regeneration. However, whether stem cells from exfoliated deciduous teeth (SHED)-secreted exosomes can improve the therapeutic potential of periodontitis is largely unknown.

OBJECTIVE

Here, we aim to evaluate the effect of SHED-exosomes on inflammation, apoptosis and osteogenic differentiation in periodontitis.

METHODS

The periodontitis cell model was constructed by stimulating periodontal ligament stem cells (PDLSCs) with lipopolysaccharide (LPS), and the periodontitis rats were established by ligation.

RESULTS

First, we isolated exosomes from the SHED, and we figured out that exosomes secreted by SHED were enriched in miR-92a-3p and the exosomes enhanced proliferation and osteogenic differentiation and reduced apoptosis and inflammatory responses in PDLSCs. In addition, we found that SHED-exosomes alleviated inflammatory effect and elevated the expression of osteogenic-related genes in periodontitis rat model. Moreover, miR-92a-3p targeted downstream Krüppel-Like Transcription Factor 4 (KLF4) and regulated the PI3K/AKT pathway. Finally, our data indicated that upregulation of KLF4 or activation of PI3K/AKT by 740Y-P counteracted the inhibitory effect of SHED-exosomes on periodontitis progression.

CONCLUSION

Taken together, our finding revealed that exosomal miR-92a-3p derived from SHED contributed to the alleviation of periodontitis development and progression through inactivating the KLF4/PI3K/AKT signaling pathway, which may provide a potential target for the treatment of periodontitis.

Proanthocyanidins Ameliorate LPS-Inhibited Osteogenesis of PDLSCs by Restoring Lysine Lactylation

Periodontitis is a bacteria-induced inflammatory disease characterized by the progressive destruction of periodontal supporting tissues. Periodontal ligament stem cells (PDLSCs) are capable of differentiating into osteoblasts, which is an important stem cell source for endogenous periodontal tissue regeneration. Lysine lactylation (Kla) is a novel post-translational modification of proteins that is recently thought to be associated with osteogenic differentiation. Here, we found that lactylation levels are reduced both in the periodontal tissue of rats with periodontitis and lipopolysaccharide (LPS)-stimulated human PDLSCs. Proanthocyanidins were able to promote the osteogenesis of inflamed PDLSCs by restoring lactylation levels. Mechanistically, proanthocyanidins increased lactate production and restored the lactylation levels of PDLSCs, which recovered osteogenesis of inflamed PDLSCs via the Wnt/β-catenin pathway. These results provide evidence on how epigenetic regulation by pharmacological agents influence the osteogenic phenotype of stem cells and the process of periodontal tissue repair. Our current study highlights the valuable potential of natural product proanthocyanidins in the regenerative engineering of periodontal tissues.

METTL3-Mediated m6A Modification Regulates the Osteogenic Differentiation through LncRNA CUTALP in Periodontal Mesenchymal Stem Cells of Periodontitis Patients

Objective

Periodontitis is a chronic inflammatory disease that causes loss of periodontal support tissue. Our objective was to investigate the mechanism by which METTL3-mediated N6-methyladenosine modification regulates the osteogenic differentiation through lncRNA in periodontal mesenchymal stem cells in patients with periodontitis (pPDLSCs). Material and Methods. We carried out a series of experiments, including methylated RNA immunoprecipitation-PCR, quantitative real-time polymerase chain reaction, and western blotting. The expressions of alkaline phosphatase (ALP), Runx2, Col1, Runx2 protein level, ALP staining, and Alizarin red staining were used to demonstrate the degree of osteogenic differentiation.

Results

We found that METTL3 was the most significantly differentially expressed methylation-related enzyme in pPDLSCs and promoted osteogenic differentiation of pPDLSCs. METTL3 regulated the stability and expression of lncRNA CUTALP, while lncRNA CUTALP promoted osteogenic differentiation of pPDLSCs by inhibiting miR-30b-3p. At different time points of osteogenic differentiation, lncRNA CUTALP expression was positively correlated with Runx2, while miR-30b-3p showed the opposite pattern. The attenuated osteogenic differentiation induced by METTL3 knockdown was recovered by lncRNA CUTALP overexpression. The attenuated osteogenic differentiation induced by lncRNA CUTALP knockdown could be reversed by the miR-30b-3p inhibitor.

Conclusions

In summary, METTL3/lncRNA CUTALP/miR-30b-3p/Runx2 is a regulatory network in the osteogenic differentiation of pPDLSCs.

Celastrol attenuates diabetic nephropathy by upregulating SIRT1-mediated inhibition of EZH2related wnt/β-catenin signaling

Proteinuria is an independent risk factor for the progression of diabetic nephropathy (DN) and an imbalance in podocyte function aggravates proteinuria. Celastrol is the primary active ingredient of T. wilfordii, effective in treating DN renal injury; however, the mechanisms underlying its effect are unclear. We explored how celastrol prevents DN podocyte damage using in vivo and in vitro experiments. We randomly divided 24 male C57BLKS/J mice into three groups: db/m (n = 8), db/db (n = 8), and celastrol groups (db/db + celastrol, 1 mg/kg/d, gavage administration, n = 8). In vivo experiments lasted 12 weeks and intervention lasted ten weeks. Serum samples and kidney tissues were collected for biochemical tests, pathological staining, transmission electron microscopy, fluorescencequantitation polymerase chain reaction, and western blotting analysis. In vitro experiments to elaborate the mechanism of celastrol protection were performed on high glucose (HG)-induced podocyte injury. Celastrol reduced blood glucose levels and renal function index in db/db mice, attenuated renal histomorphological injury and glomerular podocyte foot injuries, and induced significant anti-inflammatory effects. Celastrol upregulated silent information regulator 2 related enzyme 1(SIRT1) expression and downregulated enhancer of zeste homolog (EZH2), inhibiting the wnt/β-catenin pathway-related molecules, such as wnt1, wnt7a, and β-catenin. SIRT1 repressed the promoter activity of EZH2, and was co-immunoprecipitated with EZH2 in mouse podocyte cells (MPC5). SIRT1 knockdown aggravated the protective effects of celastrol on MPC5 cells. Celastrol protected podocyte injury via SIRT1/EZH2, which participates in the wnt/β-catenin pathway. Overall, celastrol-mediated SIRT1 upregulation inhibited the EZH2-related wnt/β-catenin signaling pathway to attenuate DN and podocyte injury, providing a theoretical basis for celastrol clinical application.

Long non-coding RNA telomerase RNA elements improve glucocorticoid-induced osteoporosis by EZH2 to regulate DKK1

BACKGROUND

Glucocorticoid-induced osteoporosis is the most common secondary cause of osteoporosis, which increases the risk of fracture. Long non-coding RNA telomerase RNA elements (TERC) has been proven to be closely related to osteoporosis. However, the role of TERC in glucocorticoid-induced osteoporosis and its underlying molecular mechanism remains unclear.

METHODS

The in vitro model of osteoporosis was established after bone marrow mesenchymal stem cells (BMSCs) were exposed to dexamethasone (DEX). The cell viability, alkaline phosphatase (ALP) activity and mineralized nodules of BMSCs were evaluated. The messenger RNA and protein levels were detected by quantitative real-time polymerase chain reaction and Western blot. The interaction between TERC, enhancer of zeste homolog 2 (EZH2) and dickkopf-1 (DKK1) was confirmed by chromatin immunoprecipitation and RNA immunoprecipitation assays.

RESULTS

Bone marrow mesenchymal stem cells were isolated, identified and induced osteogenic differentiation. The findings showed that the levels of osteogenic marker genes, including ALP, Runt-related transcription factor 2 (RUNX2) and osteocalcin (OCN) in BMSCs were increased dependent on the osteogenic induction time. Similarly, TERC was significantly increased, but DKK1 was significantly decreased during BMSC osteogenic differentiation. Functional research showed that TERC overexpression promoted cell viability, ALP activity and mineralized nodules of BMSCs and increased the levels of osteogenic differentiation-related genes (ALP, RUNX2 and OCN), and TERC overexpression increased EZH2 protein level. Moreover, the decrease of cell viability, ALP activity and mineralized nodules induced by DEX was reversed by TERC overexpression. Furthermore, TERC inhibited DKK1 expression by promoting the histone modification of DKK1, and TERC overexpression alleviated DEX suppressed osteogenic differentiation of BMSCs by interaction with EZH2 to regulate DKK1.

CONCLUSION

Our findings illustrated that TERC overexpression alleviated DEX-induced osteoporosis by recruiting EZH2 to regulate DKK1. Our research provided a novel direction for the treatment of glucocorticoid-induced osteoporosis.

Baricitinib alleviates lipopolysaccharide‑induced human periodontal ligament stem cell injury and promotes osteogenic differentiation by inhibiting JAK/STAT signaling

Periodontitis is the chronic inflammation of the periodontal tissue. The present study aimed to investigate the role of baricitinib, a Janus kinase (JAK)1/2 inhibitor, in periodontitis by using a lipopolysaccharide (LPS)-induced human periodontal ligament stem cell (PDLSC) model. The viability of PDLSCs stimulated by LPS was assessed in the presence of baricitinib by Cell Counting Kit-8 assay. The induction of oxidative stress was evaluated by detecting the intracellular reactive oxygen species (ROS) levels, superoxide dismutase (SOD) activity and glutathione (GSH) content. ELISA and reverse transcription-quantitative PCR were used to determine the levels of inflammatory factors TNF-α, IL-1β and IL-6. Alkaline phosphatase (ALP) activity and alizarin red staining were used to assess the osteogenic differentiation of PDLSCs. The expression levels of osteogenic differentiation- and JAK/signal transducer and activator of transcription (STAT) signaling-associated proteins were estimated with western blotting. RO8191, an agonist of the JAK/STAT pathway, was used to treat PDLSCs to investigate the regulatory mechanism of baricitinib. The results indicated that baricitinib elevated the LPS-induced decrease in cell viability. LPS-triggered oxidative stress and inflammation were inhibited by baricitinib, as demonstrated by the decreased levels of ROS, TNF-α, IL-1β, IL-6 and increased levels of SOD and GSH. In addition, baricitinib caused a marked elevation in ALP activity and mineralization ability of PDLSCs, as determined by the upregulated osteocalcin and Runt-related transcription factor 2 expression. Moreover, the expression levels of phosphorylated (p)-JAK1, p-JAK2 and p-STAT3 were downregulated by baricitinib in a dose-dependent manner. Furthermore, addition of RO8191 restored the effect of baricitinib on the induction of oxidative stress, inflammation and osteogenic differentiation of PDLSCs exposed to LPS. Collectively, these findings suggested that baricitinib alleviated oxidative stress and inflammation and promoted osteogenic differentiation of LPS-induced PDLSCs by inhibiting JAK/STAT signaling.

DNA Methylation and Histone Modification in Dental-derived Mesenchymal Stem Cells

Epigenetic regulation, mainly involving DNA methylation, histone modification, and noncoding RNAs (ncRNAs), is essential for the regulation of multiple cellular processes. Dental-derived mesenchymal stem cells (DMSCs), a kind of multipotent cells derived from dental tissues, are impactful in regenerative medicine. Recent studies have shown that epigenetic regulation plays a major role in DMSCs. Therefore, exploring how epigenetic regulation is involved in DMSCs may be of guiding significance for tissue repair and regeneration or for exploring more effective treatments. A number of research of ncRNAs in DMSCs have been reported. However, little is known about the roles of DNA methylation and histone modifications in DMSCs. In this review, we summarize the important roles of DNA methylation and histone modifications of the fate of DMSCs.

TBX3 regulates the transcription of VEGFA to promote osteoblasts proliferation and microvascular regeneration

Objective

Osteochondral decellularization can promote local vascular regeneration, but the exact mechanism is unknown. The aim of this study is to study osteogenic microvascular regeneration in single cells.

Methods

The scRNA-seq dataset of human periosteal-derived cells (hPDCs) were analyzed by pySCENIC. To examine the role of TBX3 in osteogenesis and vascularization, cell transfection, qRT-PCR, western blot, and CCK-8 cell proliferation assays were performed.

Results

TCF7L2, TBX3, FLI1, NFKB2, and EZH2 were found to be transcription factors (TFs) most closely associated with corresponding cells. The regulatory network of these TFs was then visualized. Our study knocked down the expression of TBX3 in human osteoblast cell lines. In the TBX3 knockdown group, we observed decreased expression of VEGFA, VEGFB, and VEGFC. Moreover, Western blot analysis showed that downregulating TBX3 resulted in a reduction of VEGFA expression. And TBX3 stimulated osteoblast proliferation in CCK-8 assays.

Conclusion

TBX3 regulates VEGFA expression and promotes osteoblast proliferation in skeletal microvasculature formation. The findings provide a theoretical basis for investigating the role of TBX3 in promoting local vascular regeneration.

CUL4B Upregulates RUNX2 to Promote the Osteogenic Differentiation of Human Periodontal Ligament Stem Cells by Epigenetically Repressing the Expression of miR-320c and miR-372/373-3p

Mesenchymal stem cells (MSCs) within the periodontal ligament (PDL), termed periodontal ligament stem cells (PDLSCs), have a self-renewing capability and a multidirectional differentiation potential. The molecular mechanisms that regulate multidirectional differentiation, such as the osteogenic differentiation of PDLSCs, remain to be elucidated. Cullin 4B (CUL4B), which assembles the CUL4B-RING ubiquitin ligase (CRL4B) complex, is involved in regulating a variety of developmental and physiological processes including the skeletal development and stemness of cancer stem cells. However, nothing is known about the possible role of CUL4B in the osteogenic differentiation of PDLSCs. Here, we found that knockdown of CUL4B decreased the proliferation, migration, stemness and osteogenic differentiation ability of PDLSCs. Mechanistically, we demonstrate that CUL4B cooperates with the PRC2 complex to repress the expression of miR-320c and miR-372/373-3p, which results in the upregulation of RUNX2, a master transcription factor (TF) that regulates osteogenic differentiation. In brief, the present study reveals the role of CUL4B as a new regulator of osteogenic differentiation in PDLSCs.

miR-141-3p Regulates EZH2 to Attenuate Porphyromonas gingivalis Lipopolysaccharide-Caused Inflammation and Inhibition of Osteogenic Differentiation in Human Periodontal Ligament Stem Cells

Objective

miR-141-3p has been demonstrated to be both anti-inflammatory and osteoprotective. This study is aimed at investigating the effect of miR-141-3p on osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) stimulated by Porphyromonas gingivalis lipopolysaccharide (PgLPS) and its mechanism.

Methods

PgLPS was used to induce an inflammatory environment, and overexpression of miR-141-3p was done to assess its effect on hPDLSCs in an inflammatory environment. The level of miR-141-3p and EZH2 in hPDLSCs from each treatment group was detected via qRT-PCR, and the inflammatory factors IL-6 and IL-8 in the supernatant of each group were detected by ELISA. ALP staining and alizarin red staining were used to assess the effect of miR-141-3p on the osteogenic differentiation ability of hPDLSCs, and also, western blot was used to detect expression of osteogenic differentiation-related proteins. Further, dual-luciferase reporter assay examined whether miR-141-3p targeted EZH2.

Results

PgLPS led to a significant decrease of miR-141-3p in hPDLSCs. Overexpression of miR-141-3p could enhance ALP activity and alizarin red staining intensity and increase Runx2, OPN and OCN protein expression levels in PgLPS-treated hPDLSCs. Additionally, miR-141-3p could reduce IL-6 and IL-8. miR-141-3p could target and negatively regulate EZH2, and overexpression of EZH2 reversed the promoting effect of miR-141-3p on osteogenic differentiation.

Conclusion

miR-141-3p can attenuate PgLPS-induced inhibition of osteogenic differentiation and inflammation in hPDLSCs by negatively regulating EZH2.

EZH2 Regulates Lipopolysaccharide-Induced Periodontal Ligament Stem Cell Proliferation and Osteogenesis through TLR4/MyD88/NF-κB Pathway

Background

Periodontitis induced by bacteria especially Gram-negative bacteria is the most prevalent chronic inflammatory disease worldwide. Emerging evidence supported that EZH2 plays a significant role in the inflammatory response of periodontal tissues. However, little information is available regarding the underlying mechanism of EZH2 in periodontitis. This study is aimed at determining the potential role and underlying mechanism of EZH2 in periodontitis.

Methods

The protein levels of EZH2, H3K27ME, p-p65, p-IKB, TLR4, MyD88, Runx2, and OCN were examined by western blot assay. Proliferation was evaluated by CCK8 assay. The levels of TNFα, IL1β, and IL6 were detected by ELISA assay. Migration was detected by wound healing assay. The distribution of p65 was detected by immunofluorescence. The formation of mineralized nodules was analyzed using alizarin red staining.

Results

LPS stimulation significantly promoted EZH2 and H3K27me3 expression in primary human periodontal ligament stem cells (PDLSCs). Targeting EZH2 prevented LPS-induced upregulation of the inflammatory cytokines and inhibition of cell proliferation and migration. Furthermore, EZH2 knockdown attenuated the TLR4/MyD88/NF-κB signaling to facilitate PDLSC osteogenesis.

Conclusions

Modulation of the NF-κB pathway through the inhibition of EZH2 may offer a new perspective on the treatment of chronic apical periodontitis.

The virulence factor GroEL directs the osteogenic and adipogenic differentiation of human periodontal ligament stem cells through the involvement of JNK/MAPK and NF-κB signaling

OBJECTIVE

GroEL, a bacterial metabolite, is an important stimulator of inflammation. The aim of this study is to confirm the effect of the virulence factor GroEL on differentiation potential of periodontal ligament (PDL) stem cells (PDLSCs) and the potential mechanisms.

METHODS

PDLSCs were obtained from extracted human premolars. GroEL was administered to osteogenic- and adipogenic-induced hPDLSCs. Alkaline phosphatase (ALP) staining, Alizarin Red staining and Oil Red staining were performed. Gene and protein expression were separately measured by qPCR and Western blotting. The expression and localization of activated signaling factors were confirmed by immunofluorescence staining. The inhibitors of myeloid differentiation factor 88 (MyD88, an adaptor protein of TLRs), JNK/MAPK and NF-κB signaling were used to verify their specific effects.

RESULTS

First, we found that GroEL inhibited the osteogenic differentiation and enhanced the adipogenic differentiation of hPDLSCs. Next, we found that GroEL increased the expression of TLR2 and TLR4 and GroEL activated JNK/MAPK and NF-κB signaling, which can be blocked by inhibition of MyD88. Finally, we found that inhibition of MyD88 restored GroEL-induced osteogenic and adipogenic differentiation and blocking JNK/MAPK or NF-κB signaling partly restored GroEL effects.

CONCLUSION

In the current study, we revealed a potential interaction between bacteria and host cells by showing that GroEL directs the osteogenic and adipogenic differentiation of hPDLSCs by the involvement of JNK/MAPK and NF-κB signaling. This study provides evidence that bacterial products can influence the differentiation of stem cells and reveals potential effect of GroEL on the context of tissue regeneration.