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

The interconnection between periodontitis and HIV-1 latency: Molecular mechanisms and therapeutic insights

Periodontitis is one of the major global public health problems associated with the occurrence and development of diverse systemic diseases, especially acquired immune deficiency syndrome (AIDS), necessitating further research and clinical attention. The persistence of HIV-1 latency poses a significant challenge to the attainment of a functional cure for AIDS, despite the introduction of highly active antiretroviral therapy (HAART). A similar mechanistic basis between periodontitis and HIV-1 latency has been revealed by many studies, suggesting possible mechanisms whereby periodontitis and HIV-1 latency may mutually influence each other. Therefore, we aimed to systematically summarize the current research on periodontitis and HIV-1 latency to investigate their potential correlations. This study revealed several common hubs for periodontitis and HIV-1 latency in the nuclear factor kappa-B (NF-κB) signaling pathway and other signaling pathways, including the Wnt/β-catenin pathway, bromodomain-containing protein 4 (BRD4), protein kinase C (PKC), the NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome, programmed cell death protein 1 (PD-1), histone deacetylases (HDACs), and the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway. Furthermore, we will discuss the hypothesis that periodontal pathogens may represent the unifying mechanism elucidating the intricate interconnection between periodontitis and HIV-1 latency. This article presents a detailed and comprehensive overview of the relationship underlying periodontitis and HIV-1 latency in terms of molecular mechanisms, which may provide novel theoretical insight into the pathogenesis of periodontitis and HIV-1 latency and reveal suitable therapeutic targets for the two diseases.

KAT3B-mediated succinylation of DERL3 suppresses osteogenic differentiation by promoting M1/M2 macrophage polarization

Periodontitis is a chronic inflammatory disease influenced by macrophage polarization. Additionally, succinylation-enriched Porphyromonas gingivalis is a pathogenic factor of periodontitis. However, the role of succinylation in the pathogenesis of periodontitis remains unclear. This study aimed to investigate the effects of a succinyltransferase KAT3B on macrophage polarization, osteogenic differentiation, and the molecular mechanism. Macrophages RAW264.7 were cocultured with MC3T3-E1-differentiated osteoblasts, and macrophage polarization and osteogenic differentiation were evaluated. iTRAQ-based proteomic analysis identified that DERL3 was highly expressed in lipopolysaccharide (LPS)-treated MC3T3-E1 cells. The TLR4/MyD88 pathway is closely related to inflammatory response. Thus, the succinylation of DERL3 and the TLR4/MyD88 pathway were assessed using immunoblotting. The results showed that KAT3B-mediated succinylation was increased in LPS-treated MC3T3-E1 cells and patients with periodontitis. Knockdown of KAT3B inhibited macrophage M1-like polarization and promoted M2-like polarization, thereby promoting osteogenic differentiation in LPS-treated osteoblasts. Mechanically, overexpression of KAT3B promoted the succinylation of DERL3 and stabilized this protein, thereby upregulating DERL3 expression. Rescue experiments showed that DERL3 reversed the promotion of osteogenic differentiation and M2/M1 macrophage polarization caused by KAT3B knockdown. Moreover, DERL3 activated the TLR4/MyD88 pathway, and inhibition of this pathway reversed macrophage polarization and osteogenesis mediated by DERL3. In vivo experiments showed that KAT3B knockdown attenuated experimental periodontitis in rats. In conclusion, silencing of KAT3B promotes osteogenic differentiation by inducing M2/M1 macrophage polarization through the succinylation DERL3, which regulates the TLR4/MyD88 pathway, thereby attenuating periodontitis. These findings suggest that KAT3B may be a promising therapeutic target for periodontitis.

Epigenetic control of dental stem cells: progress and prospects in multidirectional differentiation

Dental stem cells, with their exceptional proliferative capacity and multidirectional differentiation potential, hold significant promise for dental and oral tissue regeneration. Epigenetic inheritance, which involves stable and heritable changes in gene expression and function without alterations to the DNA sequence, plays a critical role in numerous biological processes. Environmental factors are particularly influential in epigenetic inheritance, as variations in exposure can lead to changes in epigenetic modifications that subsequently impact gene expression. Epigenetic mechanisms are widely involved in processes such as bone homeostasis, embryogenesis, stem cell fate determination, and disease development. Recently, the epigenetic regulation of dental stem cells has attracted considerable research attention. This paper reviews studies focused on the epigenetic mechanisms governing the multidirectional differentiation of dental stem cells.

Dehydroepiandrosterone promotes ovarian angiogenesis and improves ovarian function in a rat model of premature ovarian insufficiency by up-regulating HIF-1α/VEGF signalling

RESEARCH QUESTION

What impact does dehydroepiandrosterone (DHEA) have on ovarian angiogenesis and function in a rat model of with premature ovarian insufficiency (POI), and what are the potential mechanisms of action?

DESIGN

DHEA was added to a culture of human microvascular endothelial cells (HMEC-1) to investigate its effects on cell proliferation, migration and tube formation. A rat model of POI was established by intraperitoneal injection of cyclophosphamide, followed by continuous oral administration of DHEA or vehicle for 28 days. Ovarian angiogenesis, follicular growth and granulosa cell survival in ovarian tissues were assessed through haematoxylin and eosin staining, immunohistochemistry and TdT (terminal deoxynucleotidyl transferase)-mediated dUTP nick-end labelling (TUNEL). The effect of DHEA on the fertility of rats with POI was evaluated in pregnant animals. The expression levels of characteristic genes and proteins in the hypoxia-inducible factor (HIF)-1α/vascular endothelial growth factor (VEGF) pathway was determined using quantitative reverse transcription PCR and western blotting.

RESULTS

In-vitro experiments revealed that DHEA stimulated the proliferation, migration and tube formation of HMEC-1. In in-vivo studies, DHEA treatment improved the disruption of the oestrous cycle and hormone imbalances in POI rats. Key genes in the HIF-1α/VEGF pathway exhibited up-regulated expression, promoting ovarian angiogenesis in POI rats, and enhancing follicular development and granulosa cell survival, thereby restoring fertility in rats.

CONCLUSIONS

DHEA can potentially restore ovarian function in rats with cyclophosphamide-induced POI by up-regulating HIF-1α/VEGF signalling, which promotes the growth of blood vessels in the ovaries.

Long non-coding RNA LncTUG1 regulates favourable compression force-induced cementocytes mineralization via PU.1/TLR4/SphK1 signalling

Orthodontic tooth movement (OTM) is a highly coordinated biomechanical response to orthodontic forces with active remodelling of alveolar bone but minor root resorption. Such antiresorptive properties of root relate to cementocyte mineralization, the mechanisms of which remain largely unknown. This study used the microarray analysis to explore long non-coding ribonucleic acids involved in stress-induced cementocyte mineralization. Gain- and loss-of-function experiments, including Alkaline phosphatase (ALP) activity and Alizarin Red S staining, quantitative real-time polymerase chain reaction (qRT-PCR), Western blot, and immunofluorescence analyses of mineralization-associated factors, were conducted to verify long non-coding ribonucleic acids taurine-upregulated gene 1 (LncTUG1) regulation in stress-induced cementocyte mineralization, via targeting the Toll-like receptor 4 (TLR4)/SphK1 axis. The luciferase reporter assays, chromatin immunoprecipitation assays, RNA pull-down, RNA immunoprecipitation, and co-localization assays were performed to elucidate the interactions between LncTUG1, PU.1, and TLR4. Our findings indicated that LncTUG1 overexpression attenuated stress-induced cementocyte mineralization, while blocking the TLR4/SphK1 axis reversed the inhibitory effect of LncTUG1 on stress-induced cementocyte mineralization. The in vivo findings also confirmed the involvement of TLR4/SphK1 signalling in cementocyte mineralization during OTM. Mechanistically, LncTUG1 bound with PU.1 subsequently enhanced TLR4 promotor activity and thus transcriptionally elevated the expression of TLR4. In conclusion, our data revealed a critical role of LncTUG1 in regulating stress-induced cementocyte mineralization via PU.1/TLR4/SphK1 signalling, which might provide further insights for developing novel therapeutic strategies that could protect roots from resorption during OTM.

The critical role of toll-like receptor 4 in bone remodeling of osteoporosis: from inflammation recognition to immunity

Osteoporosis is a common chronic metabolic bone disorder. Recently, increasing numbers of studies have demonstrated that Toll-like receptor 4 (TLR4, a receptor located on the surface of osteoclasts and osteoblasts) plays a pivotal role in the development of osteoporosis. Herein, we performed a comprehensive review to summarize the findings from the relevant studies within this topic. Clinical data showed that TLR4 polymorphisms and aberrant TLR4 expression have been associated with the clinical significance of osteoporosis. Mechanistically, dysregulation of osteoblasts and osteoclasts induced by abnormal expression of TLR4 is the main molecular mechanism underlying the pathological processes of osteoporosis, which may be associated with the interactions between TLR4 and NF-κB pathway, proinflammatory effects, ncRNAs, and RUNX2. In vivo and in vitro studies demonstrate that many promising substances or agents (i.e., methionine, dioscin, miR-1906 mimic, artesunate, AEG-1 deletion, patchouli alcohol, and Bacteroides vulgatus) have been able to improve bone metabolism (i.e., inhibits bone resorption and promotes bone formation), which may partially attribute to the inhibition of TLR4 expression. The present review highlights the important role of TLR4 in the clinical significance and the pathogenesis of osteoporosis from the aspects of inflammation and immunity. Future therapeutic strategies targeting TLR4 may provide a new insight for osteoporosis treatment.

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.

Knockdown of Bach1 protects periodontal bone regeneration from inflammatory damage

Periodontal bone regeneration is a major challenge in the treatment of periodontitis. However, the regenerative vitality of periodontal ligament cells (PDLCs) declines in the environment of periodontitis and accompanying oxidative stress. This study aimed to investigate the functional mechanisms of Bach1, a transcriptional suppressor involved in oxidative stress response, and its regulation of PDLC osteogenesis under inflammatory conditions. We observed a significant elevation in Bach1 expression in periodontal tissues with periodontitis and PDLCs under inflammatory conditions. Knockdown of Bach1 alleviated the inflammation-induced oxidative stress level and partly offset the inhibitory effect of inflammatory conditions on osteogenesis, as well as the expression of osteogenic genes BMP6, OPG and RUNX2. Similarly, knockdown of Bach1 protects PDLCs from inflammatory damage to periodontal bone regeneration in vivo. Furthermore, we found that Bach1 could bind to the histone methyltransferase EZH2, and the binding increased under inflammatory conditions. Bach1 enhanced the ability of EZH2 to catalyse H3K27me3 on the promoter region of RUNX2 and BMP6, thus repressing the expression of osteoblastic genes. In conclusion, our study revealed that knockdown of Bach1 effectively rescued the osteogenesis and oxidative stress of PDLCs with inflammation. Bach1 could be a promising target for enhancing periodontal tissue regeneration under periodontitis conditions.

Signalling pathways in the osteogenic differentiation of periodontal ligament stem cells

Periodontal ligament stem cells (PDLSCs) have multidirectional differentiation potential and self-renewal abilities and are important seed cells for the regenerative repair of periodontal tissues. In recent years, many studies have identified multiple signalling pathways involved in regulating the osteogenic differentiation of PDLSCs in an inflammatory environment. In this article, we review the osteogenic differentiation of PDLSCs in an inflammatory environment in terms of signalling pathways and provide new ideas for the regenerative treatment of periodontal tissues.

Colorectal cancer and therapy response: a focus on the main mechanisms involved

Introduction

The latest GLOBOCAN 2021 reports that colorectal cancer (CRC) is the second leading cause of cancer-related death worldwide. Most CRC cases are sporadic and associated with several risk factors, including lifestyle habits, gut dysbiosis, chronic inflammation, and oxidative stress.

Aim

To summarize the biology of CRC and discuss current therapeutic interventions designed to counteract CRC development and to overcome chemoresistance.

Methods

Literature searches were conducted using PubMed and focusing the attention on the keywords such as "Current treatment of CRC" or "chemoresistance and CRC" or "oxidative stress and CRC" or "novel drug delivery approaches in cancer" or "immunotherapy in CRC" or "gut microbiota in CRC" or "systematic review and meta-analysis of randomized controlled trials" or "CSCs and CRC". The citations included in the search ranged from September 1988 to December 2022. An additional search was carried out using the clinical trial database.

Results

Rounds of adjuvant therapies, including radiotherapy, chemotherapy, and immunotherapy are commonly planned to reduce cancer recurrence after surgery (stage II and stage III CRC patients) and to improve overall survival (stage IV). 5-fluorouracil-based chemotherapy in combination with other cytotoxic drugs, is the mainstay to treat CRC. However, the onset of the inherent or acquired resistance and the presence of chemoresistant cancer stem cells drastically reduce the efficacy. On the other hand, the genetic-molecular heterogeneity of CRC often precludes also the efficacy of new therapeutic approaches such as immunotherapies. Therefore, the CRC complexity made of natural or acquired multidrug resistance has made it necessary the search for new druggable targets and new delivery systems.

Conclusion

Further knowledge of the underlying CRC mechanisms and a comprehensive overview of current therapeutic opportunities can provide the basis for identifying pharmacological and biological barriers that render therapies ineffective and for identifying new potential biomarkers and therapeutic targets for advanced and aggressive CRC.

Genome-wide Analysis of Histone H3 Lysine 27 Trimethylation Profiles in Sciatic Nerve of Chronic Constriction Injury Rats

The histone H3 lysine 27 trimethylation (H3K27me3) is one of the most important chromatin modifications, which is associated with injury-activated gene expression in Schwann cells (SCs). However, the alteration of genome-wide H3K27me3 enrichments in the development of neuropathic pain is still unknown. Here, we applied the chromatin immunoprecipitation sequencing (ChIP-seq) approach to identify the alteration of differential enrichments of H3K27me3 in chronic constriction injury (CCI) sciatic nerve of rats and potential molecular mechanisms underlying the development of neuropathic pain. Our results indicated that CCI increased the numbers of SCs displaying H3K27 methyltransferase enhancer of zeste homolog 2 (EZH2) and H3K27me3 in the sciatic nerve. ChIP-seq data showed that CCI significantly changed H3K27me3 enrichments on gene promoters in the sciatic nerve. Bioinformatics analyses exhibited that genes gaining H3K27me3 were mostly associated with regulation of cell proliferation, response to stress and oxidation-reduction process. Genes losing this mark were enriched in neuronal generation, and MAPK, cAMP as well as ERBB signaling pathways. Importantly, IL1A, CCL2, NOS2, S100A8, BDNF, GDNF, ERBB3 and C3 were identified as key genes in neuropathic pain. CCI led to significant upregulation of key genes in the sciatic nerve. EZH2 inhibitor reversed CCI-induced increases of H3K27me3 and key gene protein levels, which were accompanied by relieved mechanical allodynia and thermal hyperalgesia in CCI rats. These results indicate that genes with differential enrichments of H3K27me3 in SCs function in various cellular processes and pathways, and many are linked to neuropathic pain after peripheral nerve injury.

Dental pulp stem cells induce anti-inflammatory phenotypic transformation of macrophages to enhance osteogenic potential via IL-6/GP130/STAT3 signaling

Background

Periodontitis is a major oral condition and current treatment outcomes can be unsatisfactory. Macrophages are essential to the regeneration process, so we investigated the influence of human dental pulp stem cells (hDPSCs) on macrophage differentiation and the microenvironment and the underlying mechanism.

Methods

hDPSCs were isolated from healthy third molars extracted from patients undergoing maxillofacial surgery. The surface antigens CD73, CD45, CD90 and CD11b of the hDPSCs were detected using flow cytometry. hDPSCs were induced for osteogenic and adipogenic differentiation, and the outcome was assessed by alizarin red staining or Oil Red O staining. The IL-6 level released by hDPSCs was measured by enzyme linked immunosorbent assay (ELISA). Tohoku Hospital Pediatrics-1 (THP-1) cells were cultured and induced into macrophages by phorbol-12-myristate-13-acetate. After coculture of THP-1-derived macrophages with hDPSCs, interleukin 6 (IL-6), Argininase-1 (Arg-1), Mannose receptor C-1 (Mrc-1), inducible nitric oxide synthase (iNOS), and tumor necrosis factor-α (TNF-α) levels in the medium were measured using ELISA and quantificational RT-PCR (qRT-PCR). The numbers of CD80⁺ and CD163⁺ macrophages were counted by immunofluorescence, and GP130/STAT3 signaling protein expression was detected. After coculturing the culture medium of hDPSCs with human bone marrow stem cells (BMSCs), scratch assays and transwell assays were performed to evaluate cell migration and invasion.

Results

Alkaline phosphatase (ALP) staining, alizarin red staining, and western blots were performed to assess osteoblast differentiation. The hDPSCs were positive for surface antigens CD73 and CD90 and negative for CD45 and CD11b expression. The level of IL-6 secreted by hDPSCs significantly increased the number of CD80⁺ cells as well as the levels of Arg-1 and Mrc-1. It also promoted M2 macrophage polarization and activated GP130/STAT3 signaling. However, the medium cocultured with THP-1-derived macrophages by hDPSCs facilitated the migration, invasion, and osteogenic abilities of human bone marrow-derived stem cells (hBMSCs).

Conclusions

hDPSCs can regulate the periodontal microenvironment through IL-6 by inducing phenotypic transformation of M2 macrophages and stimulating osteogenic differentiation of BMSCs.

Epigenetic control of mesenchymal stem cells orchestrates bone regeneration

Recent studies have revealed the vital role of MSCs in bone regeneration. In both self-healing bone regeneration processes and biomaterial-induced healing of bone defects beyond the critical size, MSCs show several functions, including osteogenic differentiation and thus providing seed cells. However, adverse factors such as drug intake and body senescence can significantly affect the functions of MSCs in bone regeneration. Currently, several modalities have been developed to regulate MSCs' phenotype and promote the bone regeneration process. Epigenetic regulation has received much attention because of its heritable nature. Indeed, epigenetic regulation of MSCs is involved in the pathogenesis of a variety of disorders of bone metabolism. Moreover, studies using epigenetic regulation to treat diseases are also being reported. At the same time, the effects of epigenetic regulation on MSCs are yet to be fully understood. This review focuses on recent advances in the effects of epigenetic regulation on osteogenic differentiation, proliferation, and cellular senescence in MSCs. We intend to illustrate how epigenetic regulation of MSCs orchestrates the process of bone regeneration.

A Review on the Application of Stem Cell Secretome in the Protection and Regeneration of Retinal Ganglion Cells; a Clinical Prospect in the Treatment of Optic Neuropathies

PURPOSE

Retinal ganglion cells (RGCs) are one the most specialized neural tissues in the body. They transmit (and further process) chemoelectrical information originating in outer retinal layers to the central nervous system. In fact, the optic nerve is composed of RGC axons. Like other neural cells, RGCs will not completely heal after the injury, leading to irreversible vision loss from disorders such as glaucoma that primarily affect these cells. Several methods have been developed to protect or regenerate RGCs during or after the insult has occurred. This study aims to review the most recent clinical, animal and laboratory experiments designed for the regeneration of RGC that apply the stem cell-derived secretome.

METHODS

We extracted the studies from Web of Science (ISI), Medline (PubMed), Scopus, Embase, and Google scholar from the first record to the last report registered in 2022, using the following keywords; "secretome" OR "conditioned medium" OR "exosome" OR "extracellular vesicle" AND "stem cell" AND "RGC" OR "optic neuropathy". Any registered clinical trials related to the subject were also extracted from clinicaltrial.gov. All published original studies that express the effect of stem cell secretome on RGC cells in optic neuropathy, whether in vitro, in animal studies, or in clinical trials were included in this survey.

RESULTS

In this review, we provided an update on the existing reports, and a brief description of the details applied in the procedure. Compared to cell transplant, applying stem cell-derived secretome has the advantage of minimized immunogenicity yet preserving efficacy via its rich content of growth factors.

CONCLUSIONS

Different sources of stem cell secretomes have distinct implications in the management of RGC injury, which is the main subject of the present article.

MicroRNA-223 negatively regulates the osteogenic differentiation of periodontal ligament derived cells by directly targeting growth factor receptors

Background

MicroRNA (miRNA) is accepted as a critical regulator of cell differentiation. However, whether microRNA-223 (miR-223) could affect the osteogenic differentiation of periodontal ligament (PDL)-derived cells is still unknown. The aim of this study was to explore the mechanisms underlying the roles of miR-223 in the osteogenesis of PDL-derived cells in periodontitis.

Methods

Microarray analysis and real-time polymerase chain reaction (RT-PCR) were used to identify difference in miR-223 expression pattern between healthy and inflamed gingival tissue. The target genes of miR-223 were predicted based on Targetscan and selected for enrichment analyses based on Metascape database. The gain-and loss-of-function experiments were performed to discuss roles of miR-223 and growth factor receptor genes in osteogenic differentiation of PDL-derived cells. The target relationship between miR-223 and growth factor receptor genes was confirmed by a dual luciferase assay. Osteogenic differentiation of PDL-derived cells was assessed by Alizarin red staining, RT-PCR and western blot detection of osteogenic markers, including osteocalcin (OCN), osteopontin (OPN) and runt-related transcription factor 2 (Runx2).

Results

MiR-223 was significantly increased in inflamed gingival tissues and down-regulated in PDL-derived cells during osteogenesis. The expression of miR-223 in gingival tissues was positively correlated with the clinical parameters in periodontitis patients. Overexpression of miR-223 markedly inhibited PDL-derived cells osteogenesis, which was evidenced by reduced Alizarin red staining and osteogenic markers expressions. Furthermore, two growth factor receptor genes, including fibroblast growth factor receptor 2 (FGFR2) and transforming growth factor beta receptor 2 (TGFβR2), were revealed to be direct targets of miR-223 and shown to undergo up-regulation in PDL-derived cells during osteogenesis. Moreover, suppression of FGFR2 or TGFβR2 dramatically blocked PDL-derived cells osteogenic differentiation.

Conclusions

Our study provides novel evidence that miR-223 can be induced by periodontitis and acts as a negative regulator of PDL-derived cells osteogenesis by targeting two growth factor receptors (TGFβR2 and FGFR2).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03676-1.

Identification of Key Genes and Pathways Associated with Oxidative Stress in Periodontitis

Background and Objective. Oxidative stress has been associated with the progression of periodontitis. However, oxidative stress-related genes (OS-genes) have not been used as disease-specific biomarkers that correlate with periodontitis progression. This study is aimed at screening the key OS-genes and pathways in periodontitis by bioinformatics methods. Methods. The differentially expressed genes (DEGs) were identified using periodontitis-related microarray from the GEO database, and OS-genes were extracted from GeneCards database. The intersection of the OS-genes and the DEGs was considered as oxidative stress-related DEGs (OS-DEGs) in periodontitis. The Pearson correlation and protein-protein interaction analyses were used to screen key OS-genes. Gene set enrichment, functional enrichment, and pathway enrichment analyses were performed in OS-genes. Based on key OS-genes, a risk score model was constructed through logistic regression, receiver operating characteristic curve, and stratified analyses. Results. In total, 74 OS-DEGs were found in periodontitis, including 65 upregulated genes and 9 downregulated genes. Six of them were identified as key OS-genes (CXCR4, SELL, FCGR3B, FCGR2B, PECAM1, and ITGAL) in periodontitis. All the key OS-genes were significantly upregulated and associated with the increased risk of periodontitis. Functional enrichment analysis showed that these genes were mainly associated with leukocyte cell-cell adhesion, phagocytosis, and cellular extravasation. Pathway analysis revealed that these genes were involved in several signaling pathways, such as leukocyte transendothelial migration and osteoclast differentiation. Conclusion. In this study, we screened six key OS-genes that were screened as risk factors of periodontitis. We also identified multiple signaling pathways that might play crucial roles in regulating oxidative stress damage in periodontitis. In the future, more experiments need to be carried out to validate our current findings.

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.

Exosomes Derived From Human Gingival Mesenchymal Stem Cells Attenuate the Inflammatory Response in Periodontal Ligament Stem Cells

This study aimed to explore the effects of exosomes derived from human gingival mesenchymal stem cells (GMSC-Exo) on the inflammatory response of periodontal ligament stem cells (PDLSCs) in an inflammatory microenvironment in order to restore the regenerative potential of PDLSCs, which promotes periodontal tissue regeneration in patients with periodontitis. Periodontitis is a chronic infectious disease characterized by periodontal tissue inflammation and alveolar bone destruction. PDLSCs are regarded as promising seed cells for restoring periodontal tissue defects because of their ability to regenerate cementum/PDL-like tissue and alveolar bone. However, PDLSCs in the inflammatory environment show significantly attenuated regenerative potential. GMSC-Exo have been reported to have anti-inflammatory and immunosuppressive properties. In this study, we investigated the effects of GMSC-Exo on the inflammatory response of PDLSCs induced by lipopolysaccharides (LPS). LPS was used to simulate the inflammatory microenvironment of periodontitis in vitro. GMSC-Exo were extracted from the culture supernatant of GMSCs by ultracentrifugation. We found that GMSC-Exo attenuated the inflammatory response of PDLSCs induced by LPS. Furthermore, compared to treatment with LPS, treatment with GMSC-Exo attenuated the expression of NF-κB signaling and Wnt5a in LPS-induced PDLSCs. In conclusion, we confirmed that GMSC-Exo could suppress the inflammatory response of PDLSCs by regulating the expression of NF-κB signaling and Wnt5a, which paves the way for the establishment of a therapeutic approach for periodontitis.

Potential Anti-Inflammatory Effects of a New Lyophilized Formulation of the Conditioned Medium Derived from Periodontal Ligament Stem Cells

The mesenchymal stem cells’ (MSCs) secretome includes the bioactive molecules released in the conditioned medium (CM), such as soluble proteins, free nucleic acids, lipids and extracellular vesicles. The secretome is known to mediate some of the beneficial properties related to MSCs, such as anti-inflammatory, anti-apoptotic and regenerative capacities. In this work, we aim to evaluate the anti-inflammatory potential of a new lyophilized formulation of CM derived from human periodontal ligament stem cells (hPDLSCs). With this aim, we treat hPDLSCs with lipopolysaccharide (LPS) and test the anti-inflammatory potential of lyophilized CM (LYO) through the evaluation of wound closure, transcriptomic and immunofluorescence analysis. LPS treatment increased the expression of TLR4 and of genes involved in its signaling and in p38 and NF-κB activation, also increasing the expression of cytokines and chemokines. Interestingly, LYO downregulated the expression of genes involved in Toll-like receptor 4 (TLR-4), nuclear factor kappa light chain enhancer of activated B cells (NF-κB) and p38 signaling. As a consequence, the genes encoding for cytokines and chemokines were also downregulated. Immunofluorescence acquisitions confirmed the downregulation of TLR-4 and NF-κB with the LYO treatment. Moreover, the LYO treatment also increased hPDLSCs’ migration. LYO was demonstrated to contain transforming growth factor (TGF)-β3 and vascular endothelial growth factor (VEGF). These results suggest that LYO represents an efficacious formulation with anti-inflammatory potential and highlights lyophilization as a valid method to produce stable formulations of MSCs’ secretome.

Platelet Toll-like Receptor 4–Related Innate Immunity Potentially Participates in Transfusion Reactions Independent of ABO Compatibility: An Ex Vivo Study

The role of platelet TLR4 in transfusion reactions remains unclear. This study analyzed platelet TLR4 and certain damage-associated molecular patterns (DAMPs) and evaluated how ABO compatibility affected TLR4 expression after a simulated ex vivo transfusion. A blood bank was the source of donor red blood cells. Blood from patients undergoing cardiac surgery was processed to generate a washed platelet suspension to which the donor blood was added in concentrations 1, 5, and 10% (v/v). Blood-mixing experiments were performed on four groups: a 0.9% saline control group (n = 31); a matched-blood-type mixing group (group M, n = 20); an uncross-matched ABO-specific mixing group (group S, n = 20); and an ABO-incompatible blood mixing group (group I, n = 20). TLR4 expression in the platelets was determined after blood mixing. We evaluated levels of TLR4-binding DAMPs (HMGB1, S100A8, S100A9, and SAA), lipopolysaccharide-binding protein, and endpoint proteins in the TLR4 signaling pathway. In the M, S, and I groups, 1, 5, and 10% blood mixtures significantly increased TLR4 expression (all p < 0.001) in a concentration-dependent manner. Groups M, S, and I were not discovered to have significantly differing TLR4 expression (p = 0.148). HMGB1, S100A8, and S100A9 levels were elevated in response to blood mixing, but SAA, lipopolysaccharide-binding protein, TNF-α, IL-1β, and IL-6 levels were not. Blood mixing may elicit innate immune responses by upregulating platelet TLR4 and DAMPs unassociated with ABO compatibility, suggesting that innate immunity through TLR4-mediated signaling may induce transfusion reactions.