Oral Tissue Cells Research Articles

Identification of receptors and factors associated with human coronaviruses in the oral cavity using single-cell RNA sequencing

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) ravaged the world, and Coronavirus Disease 2019 (COVID-19) exhibited highly prevalent oral symptoms that had significantly impacted the lives of affected patients. However, the involvement of four human coronavirus (HCoVs), namely SARS-CoV-2, SARS-CoV, MERS-CoV, and HCoV-229E, in oral cavity infections remained poorly understood. We integrated single-cell RNA sequencing (scRNA-seq) data of seven human oral tissues through consistent normalization procedure, including minor salivary gland (MSG), parotid gland (PG), tongue, gingiva, buccal, periodontium and pulp. The Seurat, scDblFinder, Harmony, SingleR, Ucell and scCancer packages were comprehensively used for analysis. We identified specific cell clusters and generated expression profiles of SARS-CoV-2 and coronavirus-associated receptors and factors (SCARFs) in seven oral regions, providing direction for predicting the tropism of four HCoVs for oral tissues, as well as for dental clinical treatment. Based on our analysis, it appears that various SCARFs, including ACE2, ASGR1, KREMEN1, DPP4, ANPEP, CD209, CLEC4G/M, TMPRSS family proteins (including TMPRSS2, TMPRSS4, and TMPRSS11A), and FURIN, are expressed at low levels in the oral cavity. Conversely, BSG, CTSB, and CTSL exhibit enrichment in oral tissues. Our study also demonstrates widespread expression of restriction factors, particularly IFITM1-3 and LY6E, in oral cells. Additionally, some replication, assembly, and trafficking factors appear to exhibit broad oral tissues expression patterns. Overall, the oral cavity could potentially serve as a high-risk site for SARS-CoV-2 infection, while displaying a comparatively lower degree of susceptibility towards other HCoVs (including SARS-CoV, MERS-CoV and HCoV-229E). Specifically, MSG, tongue, and gingiva represent potential sites of vulnerability for four HCoVs infection, with the MSG exhibiting a particularly high susceptibility. However, the expression patterns of SCARFs in other oral sites demonstrate relatively intricate and may only be specifically associated with SARS-CoV-2 infection. Our study sheds light on the mechanisms of HCoVs infection in the oral cavity as well as gains insight into the characteristics and distribution of possible HCoVs target cells in oral tissues, providing potential therapeutic targets for HCoVs infection in the oral cavity.

Gingival Fibroblasts Are Sensitive to Oral Cell Lysates Indicated by Their IL11 Expression.

Damaged cells that appear as a consequence of invasive dental procedures or in response to dental materials are supposed to release damage-associated signals. These damage-associated signals not only support tissue regeneration but might also contribute to unwanted fibrosis. The aim of this study was to identify a molecular target that reflects how fibroblasts respond to necrotic oral tissue cells. To simulate the cell damage, we prepared necrotic cell lysates by sonication of the osteocytic cell line IDG-SW3 and exposed them to gingival fibroblasts. RNAseq revealed a moderate increase in IL11 expression in the gingival fibroblasts, a pleiotropic cytokine involved in fibrosis and inflammation, and also in regeneration following trauma. Necrotic lysates of the human squamous carcinoma cell lines HSC2 and TR146, as well as of gingival fibroblasts, however, caused a robust increase in IL11 expression in the gingival fibroblasts. Consistently, immunoassay revealed significantly increased IL11 levels in the gingival fibroblasts when exposed to the respective lysates. Considering that IL11 is a TGF-β target gene, IL11 expression was partially blocked by SB431542, a TGF-β receptor type I kinase inhibitor. Moreover, lysates from the HSC2, TR146, and gingival fibroblasts caused a moderate smad2/3 nuclear translocation in the gingival fibroblasts. Taken together and based on IL11 expression, our findings show that fibroblasts are sensitive to damaged oral tissue cells.

The Hypothalamic-Pituitary-Thyroid Axis Equivalent in Normal and Cancerous Oral Tissues: A Scoping Review.

The hypothalamic-pituitary-thyroid (HPT) axis is crucial in regulating thyroid hormone levels that contribute to the development and homeostasis of the human body. Current literature supports the presence of a local HPT axis equivalent within keratinocytes of the skin, with thyroid hormones playing a potential role in cancer progression. However, this remains to be seen within oral tissue cells. An electronic search of Scopus and PubMed/Medline databases was conducted to identify all original publications that reported data on the production or effects of HPT axis components in normal or malignant cells of the oral cavity. The search identified 221 studies, of which 14 were eligible. Eight studies were retrospective analyses of clinical samples, one study involved both in vivo and in vitro experiments, and the remaining five studies were conducted in vitro using cell lines. The search identified evidence of effects of HPT components on oral cancer cells. However, there were limited data for the production of HPT axis components by oral tissues. We conclude that a possible role of the local HPT axis equivalent in the oral mucosa may not be established at present. The gaps in knowledge identified in this scoping review, particularly regarding the production of HPT components by oral tissues, warrant further investigation.

Methanolic Extract From Cocoa Bean (Theobroma Cacao L.) As A Potential Active Ingredient In Mouthwash

Dental plaque is a soft deposit firmly attached to the surface of teeth, formed from a mixture of saliva; such as mucin, remnants of oral tissue cells, leukocytes, lymphocytes with food debris, and bacteria resulting in the initial occurrence of tooth decay due to reduced pH. Unfortunately, currently available antiseptics-based mouthwash, used to prevent dental plaque formation, is thought to have a carcinogenic effect. Therefore, an alternative plaque was proposed using herbal antibacterial agents. Cocoa beans have anti-bacterial properties and are known to have active anti-bacterial agents, these substances are flavonoids, phenolics, alkaloids, terpenoids, saponins, and tannins. Herein, we aimed to determine the phytochemical content of methanol extract from cocoa bean (Theobroma cacao L.) and its antibacterial activities against Streptococcus mutans and subsequently studied its potential as a mouthwash active ingredient. Macerated methanolic extract of cocoa bean was investigated against clinical isolates of S. mutans. Qualitative phytochemical tests were further performed to observe the presence of flavonoids, phenolics, alkaloids, terpenoids, saponins, and tannins. The results showed that the growth of S. mutans colonies at a concentration of 1, 2, and 3% were 431×104, 142×104, and 59.5×104 CFU/mL, respectively. Addition of the extract at all concentrations (1—3%) did not affect the color, aroma, taste, and clarity of the mouthwash. An acute toxicity test on mice model confirmed that the cocoa bean-based mouthwash was safe.

Cytotoxic and Inflammatory Effects of Electronic and Traditional Cigarettes on Oral Gingival Cells Using a Novel Automated Smoking Instrument: An In Vitro Study.

Information about the potential oral health effects of vaping from electronic cigarettes (e-cigs) is still sparse and inconsistent. The purpose of this study was to compare the safety and cytotoxicity of e-cig liquid aerosols versus traditional cigarette (t-cig) smoke on human epithelial oral cells. T-cig smoke and e-cig aerosols were generated by a newly developed automated smoking instrument in order to simulate realistic user puffing behaviors. Air–liquid interface transwell cell cultures were exposed to standardized puff topography (puff duration: 2 s, puff volume: 35 mL, puff frequency: 1 puff every 60 s) of reference t-cigs or commercially available e-cigs at different air dilutions. Cell viability, morphology, and death rate were evaluated with MTT and TUNEL assays. The inflammatory cytokine gene expression of inflammatory genes was assessed by quantitative RT-PCR. E-cigs and t-cigs indicated similar adverse effects by enhancing cytotoxicity and cell death in a dose-dependent manner. E-cig aerosol and t-cig smoke treatment expressed upregulation of inflammatory cytokines up to 3.0-fold (p < 0.05). These results indicate that e-cig smoking may contribute to oral tissue–cell damage and tissue inflammation. Our approach allows the production of e-cig aerosol and t-cig smoke in order to identify harmful effects in oral tissues in vitro.

Characterization of Immune Cells in Oral Tissues of Non-human Primates.

The oral mucosa contains distinct tissue sites with immune niches capable of either immunogenic or tolerogenic responses. However, immune cell compositions within oral mucosal tissues at homeostasis have not been well-characterized in human relevant tissues. Non-human primates (NHP) are a major model for the human immune system and oral anatomy, and therefore improved understanding of NHP oral immune cell populations can provide important insights for studying disease pathologies and developing therapies. Herein, we characterize immune cell types of three sites within the oral cavity (buccal, sublingual, lingual tonsil) sampled by biopsy and cytobrush in pigtail macaques. Tonsil biopsies had more T-cells, dendritic cells (DCs), DC subtypes, and CD4+ T-cells than buccal or sublingual biopsies when normalized by tissue mass. Biopsy proved to collect more immune cells than cytobrushes, however frequencies of CD45+ subpopulations were comparable between methods. Live cells isolated from biopsied tonsils had greater CD45+ leukocyte frequencies (mean 31.6 ± SD 20.4%) than buccal (13.8 ± 4.6%) or sublingual (10.0 ± 5.1%) tissues. T-cells composed more than half of the CD45+ population in sublingual tissue (60.1 ± 9.6%) and the tonsil (54.6 ± 7.5%), but only 31.9 ± 7.2% in buccal samples. CD20+ B-cells composed a greater percentage of CD45+ leukocytes in the tonsil (12.8 ± 9.1%) than buccal (1.2 ± 1.0%) or sublingual tissues (0.8 ± 1.2%). Immune population comparisons are also made between sex and age. These results present an important step for understanding the oral immune environment, oral disease, and site-specific therapy development.

Human osteoblast and fibroblast response to oral implant biomaterials functionalized with non-thermal oxygen plasma

Plasma-treatment of oral implant biomaterials prior to clinical insertion is envisaged as a potential surface modification method for enhanced implant healing. To investigate a putative effect of plasma-functionalized implant biomaterials on oral tissue cells, this investigation examined the response of alveolar bone osteoblasts and gingival fibroblasts to clinically established zirconia- and titanium-based implant surfaces for bone and soft tissue integration. The biomaterials were either functionalized with oxygen-plasma in a plasma-cleaner or left untreated as controls, and were characterized in terms of topography and wettability. For the biological evaluation, the cell adhesion, morphogenesis, metabolic activity and proliferation were examined, since these parameters are closely interconnected during cell-biomaterial interaction. The results revealed that plasma-functionalization increased implant surface wettability. The magnitude of this effect thereby depended on surface topography parameters and initial wettability of the biomaterials. Concerning the cell response, plasma-functionalization of smooth surfaces affected initial fibroblast morphogenesis, whereas osteoblast morphology on rough surfaces was mainly influenced by topography. The plasma- and topography-induced differential cell morphologies were however not strong enough to trigger a change in proliferation behaviour. Hence, the results indicate that oxygen plasma-functionalization represents a possible cytocompatible implant surface modification method which can be applied for tailoring implant surface wettability.

HEMA modulates the transcription of genes related to oxidative defense, inflammatory response and organization of the ECM in human oral cells

Objectives2-Hydroxyethyl methacrylate (HEMA) is a widely used monomer of dental resin composite materials. Incomplete curing of resins leads to elution of HEMA, which may come in contact with different cells in oral tissues. We aimed to analyze the impact of HEMA on the transcription of genes participating in detoxification of oxidative stress, inflammatory response and organization of the extracellular matrix (ECM) using human gingival fibroblasts (HGFs) and human oral keratinocytes (OKF6/TERT2). MethodsCells were grown in monolayer cultures and treated with different HEMA concentrations (0.5–10mM). H33342 and LDH assays were used to determine HEMA-caused cytotoxicity. Quantitative RT-PCR was used to analyze mRNA expression of four genes related to oxidative stress and five genes each related to inflammation and organization of the ECM. ResultsHEMA caused similar concentration-dependent cytotoxicity in fibroblasts and keratinocytes. Analysis of the transcription showed that genes were regulated in both cell types after HEMA treatment. Genes related to defense against oxidative stress were transcriptionally induced, genes related to inflammation were mainly reduced and genes related to the organization of the ECM were differentially modulated. SignificanceWe analyzed concurrent and HEMA-dependent differential expression of 14 important genes, which have a special significance for cellular processes that are linked to redox and tissue homeostasis. The results suggest that HEMA has an impact on cellular redox-homeostasis with potential impairment of inflammatory responses and of the organization of the ECM in human gingival fibroblasts and oral keratinocytes as first target cells of eluted HEMA.

Human Th17 activity profile in oral chronic Graft-versus-Host Disease

Abstract Immunotherapy using allogeneic hematopoietic stem cell transplantation (alloHSCT) is highly effective; however, its use is limited by the incidence of chronic graft-versus-host disease (cGVHD). The oral cavity, which is affected by cGVHD, is a highly accessible mucosal site with its own local biofluid – saliva – but little is known about the pathogenic progression of cGVHD in oral tissues. This study examined the relationship between salivary gland gene expression, salivary proteins and the immune cell network within oral tissues at onset of oral cGVHD. Patients enrolled in NIH cGVHD trials (NCT00331968, NCT00520130, NCT01851382) were evaluated after cGVHD onset. Whole saliva from individual oral cGVHD patients (n=58) and healthy controls (n=10) was analyzed for a 13-plex panel of immune-related analytes and revealed elevated expression of tissue remodeling factors and IFN- and IL-17-induced chemokines that correlated with clinical scoring of cGVHD severity in a multivariate analysis. Microarray of patient MSG indicated canonical pathway expression including innate immune pathways, and IFN, IL-17 and IL-22-induced processes. Confocal microscopy confirmed the presence of immune cells in oral tissues. Extending our laboratory’s prior observations of Th1 effectors in BM, Th17 cells (CD4+/CD161+/IL-17+) and Type I IFN-induced factors were identified in the majority of available BM and MSG of cGVHD patients, but not in unaffected post-transplant controls. Current analyses in cGVHD patient samples implicate activation of IFN pathways and presence of Th17 cells in oral tissues in the pathogenesis of oral cGVHD, though the specific sequence and role of these cells in salivary gland pathogenesis during cGVHD remain to be determined.

Antibacterial and antibiofilm activities of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) against periodontopathic bacteria

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are two major omega-3 polyunsaturated fatty acids (n-3 PUFAs) with antimicrobial properties. In this study, we evaluated the potential antibacterial and antibiofilm activities of DHA and EPA against two periodontal pathogens, Porphyromonas gingivalis (P. gingivalis) and Fusobacterium nucleatum (F. nucleatum). MTT assay showed that DHA and EPA still exhibited no cytotoxicity to human oral tissue cells when the concentration came to 100 μM and 200 μM, respectively. Against P. gingivalis, DHA and EPA showed the same minimum inhibitory concentration (MIC) of 12.5 μM, and a respective minimum bactericidal concentration (MBC) of 12.5 μM and 25 μM. However, the MIC and MBC values of DHA or EPA against F. nucleatum were both greater than 100 μM. For early-stage bacteria, DHA or EPA displayed complete inhibition on the planktonic growth and biofilm formation of P. gingivalis from the lowest concentration of 12.5 μM. And the planktonic growth of F. nucleatum was slightly but not completely inhibited by DHA or EPA even at the concentration of 100 μM, however, the biofilm formation of F. nucleatum at 24 h was significantly restrained by 100 μM EPA. For exponential-phase bacteria, 100 μM DHA or EPA completely killed P. gingivalis and significantly decreased the viable counts of F. nucleatum. Meanwhile, the morphology of P. gingivalis was apparently damaged, and the virulence factor gene expression of P. gingivalis and F. nucleatum was strongly downregulated. Besides, the viability and the thickness of mature P. gingivalis biofilm, together with the viability of mature F. nucleatum biofilm were both significantly decreased in the presence of 100 μM DHA or EPA. In conclusion, DHA and EPA possessed antibacterial activities against planktonic and biofilm forms of periodontal pathogens, which suggested that DHA and EPA might be potentially supplementary therapeutic agents for prevention and treatment of periodontal diseases.

Localization and osteoblastic differentiation potential of neural crest-derived cells in oral tissues of adult mice

In embryos, neural crest cells emerge from the dorsal region of the fusing neural tube and migrate throughout tissues to differentiate into various types of cells including osteoblasts. In adults, subsets of neural crest-derived cells (NCDCs) reside as stem cells and are considered to be useful cell sources for regenerative medicine strategies. Numerous studies have suggested that stem cells with a neural crest origin persist into adulthood, especially those within the mammalian craniofacial compartment. However, their distribution as well as capacity to differentiate into osteoblasts in adults is not fully understood. To analyze the precise distribution and characteristics of NCDCs in adult oral tissues, we utilized an established line of double transgenic (P0-Cre/CAG-CAT-EGFP) mice in which NCDCs express green fluorescent protein (GFP) throughout their life. GFP-positive cells were scattered like islands throughout tissues of the palate, gingiva, tongue, and buccal mucosa in adult mice, with those isolated from the latter shown to form spheres, typical cell clusters composed of stem cells, under low-adherent conditions. Furthermore, GFP-positive cells had markedly increased alkaline phosphatase (a marker enzyme of osteoblast differentiation) activity and mineralization as shown by alizarin red staining, in the presence of bone morphogenetic protein (BMP)-2. These results suggest that NCDCs reside in various adult oral tissues and possess potential to differentiate into osteoblastic cells. NCDCs in adults may be a useful cell source for bone regeneration strategies.

Effects of ozone nano-bubble water on periodontopathic bacteria and oral cells - in vitro studies

The aims of the present study were to evaluate the bactericidal activity of a new antiseptic agent, ozone nano-bubble water (NBW3), against periodontopathogenic bacteria and to assess the cytotoxicity of NBW3 against human oral cells. The bactericidal activities of NBW3 against representative periodontopathogenic bacteria, Porphyromonas gingivalis (P. gingivalis) and Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) were evaluated using in vitro time-kill assays. The cytotoxicity of NBW3 was evaluated using three-dimensional human buccal and gingival tissue models. The numbers of colony forming units (CFUs)/mL of P. gingivalis and A. actinomycetemcomitans exposed to NBW3 dropped to below the lower limit of detection (<10 CFUs mL−1) after only 0.5 min of exposure. There were only minor decreases in the viability of oral tissue cells after 24 h of exposure to NBW3. These results suggest that NBW3 possesses potent bactericidal activity against representative periodontopathogenic bacteria and is not cytotoxic to cells of human oral tissues. The use of NBW3 as an adjunct to periodontal therapy would be promising.

Molecular characterization of immortalized normal and dysplastic oral cell lines.

Cell lines have been developed for modeling cancer and cancer progression. The molecular background of these cell lines is often unknown to those using them to model disease behaviors. As molecular alterations are the ultimate drivers of cell phenotypes, having an understanding of the molecular make-up of these systems is critical for understanding the disease biology modeled. Six immortalized normal, one immortalized dysplasia, one self-immortalized dysplasia, and two primary normal cell lines derived from oral tissues were analyzed for DNA copy number changes and changes in both mRNA and miRNA expression using SMRT-v.2 genome-wide tiling comparative genomic hybridization arrays, Agilent Whole Genome 4x44k expression arrays, and Exiqon V2.M-RT-PCR microRNA Human panels. DNA copy number alterations were detected in both normal and dysplastic immortalized cell lines-as well as in the single non-immortalized dysplastic cell line. These lines were found to have changes in expression of genes related to cell cycle control as well as alterations in miRNAs that are deregulated in clinical oral squamous cell carcinoma tissues. Immortal lines-whether normal or dysplastic-had increased disruption in expression relative to primary lines. All data are available as a public resource. Molecular profiling experiments have identified DNA, mRNA, and miRNA alterations for a panel of normal and dysplastic oral tissue cell lines. These data are a valuable resource to those modeling diseases of the oral mucosa, and give insight into the selection of model cell lines and the interpretation of data from those lines.

Antimicrobial Activity of Berberine against Oral Bacteria Related to Endodontic Infections

It has been established that berberine has strong antimicrobial effects. Little is known however regarding the antimicrobial activity of berberine against endodontic pathogenic bacteria or its cytotoxicity in human oral tissue cells. The antibacterial properties of berberine were tested against 5 strains of Enterococcus faecalis and type strains of Aggregatibacter actinomycetemcomitans, Prevotella nigrescens, Prevotella intermedia, and Tannerella forsythia, which are involved in endodontic infections. Antimicrobial activity was evaluated through minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) measurements. The viability of normal human gingival fibroblast (NHGF) cells after exposure to berberine was measured using a methyl thiazolyl tetrazolium (MTT) assay. The data showed that berberine has antimicrobial effects against A. actinomycetemcomitans with an MIC and MBC of 12.5 μg/ml and 25 μg/ml, respectively. In the cytotoxicity studies, cell viability was maintained at 66.1% following exposure to 31.3 μg/ml berberine. Overall, these findings suggest that berberine has antimicrobial activity against the tested bacteria. Nevertheless, lower concentrations in combination with other reagents will need to be tested before these in vitro results can be translated to clinical use.

Biostimulatory effects of low-level laser therapy on epithelial cells and gingival fibroblasts treated with zoledronic acid

Low-level laser therapy (LLLT) has been considered as an adjuvant treatment for bisphosphonate-related osteonecrosis, presenting positive clinical outcomes. However, there are no data regarding the effect of LLLT on oral tissue cells exposed to bisphosphonates. This study aimed to evaluate the effects of LLLT on epithelial cells and gingival fibroblasts exposed to a nitrogen-containing bisphosphonate—zoledronic acid (ZA). Cells were seeded in wells of 24-well plates, incubated for 48 h and then exposed to ZA at 5 μM for an additional 48 h. LLLT was performed with a diode laser prototype—LaserTABLE (InGaAsP—780 nm ± 3 nm, 25 mW), at selected energy doses of 0.5, 1.5, 3, 5, and 7 J cm−2 in three irradiation sessions, every 24 h. Cell metabolism, total protein production, gene expression of vascular endothelial growth factor (VEGF) and collagen type I (Col-I), and cell morphology were evaluated 24 h after the last irradiation. Data were statistically analyzed by Kruskal–Wallis and Mann–Whitney tests at 5% significance. Selected LLLT parameters increased the functions of epithelial cells and gingival fibroblasts treated with ZA. Gene expression of VEGF and Col-I was also increased. Specific parameters of LLLT biostimulated fibroblasts and epithelial cells treated with ZA. Analysis of these in vitro data may explain the positive in vivo effects of LLLT applied to osteonecrosis lesions.

UVB‐Induced Inflammatory Cytokine Release, DNA Damage and Apoptosis of Human Oral Compared with Skin Tissue Equivalents

People can get oral cancers from UV (290-400 nm) exposures. Besides high outdoor UV exposures, high indoor UV exposures to oral tissues can occur when consumers use UV-emitting tanning devices to either tan or whiten their teeth. We compared the carcinogenic risks of skin to oral tissue cells after UVB (290-320 nm) exposures using commercially available 3D-engineered models for human skin (EpiDerm™), gingival (EpiGing™) and oral (EpiOral™) tissues. To compare the relative carcinogenic risks, we investigated the release of cytokines, initial DNA damage in the form of cyclobutane pyrimidine dimers (CPDs), repair of CPDs and apoptotic cell numbers. We measured cytokine release using cytometric beads with flow cytometry and previously developed a fluorescent immunohistochemical assay to quantify simultaneously CPD repair rates and apoptotic cell numbers. We found that interleukin-8 (IL-8) release and the initial CPDs are significantly higher, whereas the CPD repair rates and apoptotic cell numbers are significantly lower for oral compared with skin tissue cells. Thus, the increased release of the inflammatory cytokine IL-8 along with inefficient CPD repair and decreased death rates for oral compared with skin tissue cells suggests that mutations are accumulating in the surviving population of oral cells increasing people's risks for getting oral cancers.

치아우식증 및 치주질환 원인균에 대한 Carvacrol의 항균효과

본 연구는 치아우식증 및 치주질환 원인균들에 대한 carvacrol의 항균능을 알아보고, 사람의 구강조직 세포에서 세포의 생존율을 분석하여 세포독성 정도를 알아보기 위해 실시하였다. Carvacrol의 항균능은 뮤탄스 연쇄상구균과 5종류의 치주질환 원인균을 이용하여 MIC 및 MBC 값을 측정하여 분석하였고, 세포생존율은 정상 사람 치은섬유모세포를 이용하여 MTT 분석법으로 평가하였다. 구강질환 원인균에 대한 carvacrol의 MIC 및 MBC 값은 각각 <TEX>$16-128{\mu}g/ml$</TEX>과 <TEX>$32-128{\mu}g/ml$</TEX>이었다. 세포독성 실험 결과 carvacrol은 <TEX>$128{\mu}g/ml$</TEX> 농도에서 세포생존율이 현저히 감소하였다. 따라서 carvacrol은 치아우식증과 치주질환 원인균에 대한 항균작용이 뛰어나지만, 구강조직 세포에 대해 세포독성을 가지고 있어 가글린제 및 치약 등의 구강위생용품에 활용하기 위해서는 <TEX>$64{\mu}g/ml$</TEX> 이하의 농도로 사용하고 정상 사람 치은섬유모세포에 대한 독성이 없는 다른 항균물질과 혼합하여 사용하는 것이 효과적일 것으로 생각된다. The aim of this study was to evaluate the antimicrobial effect of carvacrol against periodontopathic and cariogenic bacteria and its cytotoxicity in human oral tissue cells. We tested their antibacterial properties against mutans streptococci and five major periodontopathic bacterial species involved in periodontal disease. The antimicrobial activity was evaluated by the minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The cell viability of carvacrol on normal human gingival fibroblast (NHGF) cells was tested by metyl thiazolyl tetrazolium assay. The data showed that carvacrol had remarkable antimicrobial effect on tested bacteria with a MIC and MBC values ranged from 16 to <TEX>$128{\mu}g/ml$</TEX> and from 32 to <TEX>$128{\mu}g/ml$</TEX>, respectively. In cell toxicity studies, carvacrol had significantly decreased cell viability when NHGF cells were treated at <TEX>$128{\mu}g/ml$</TEX>. These findings suggest that carvacrol has a strong antimicrobial activity against periodontopathic and cariogenic bacteria. However, in order to use it as a component of gargling solution or toothpaste, its concentration should be below <TEX>$64{\mu}g/ml$</TEX> and other compounds having an antimicrobial activity against periodontopathic and cariogenic bacteria should be used together.

Histological analysis of epithelial stem cells during induced pluripotent stem cell-derived teratoma development

ObjectiveInduced pluripotent stem (iPS) cells can differentiate into a variety of cell types and can form teratomas when transplanted in vivo. The purpose of the present study was to investigate the developmental processes and features of epithelial tissues, and the existence of epithelial stem/progenitor cells in iPS cell-derived teratomas. Materials and methodsiPS cell-derived teratomas formed by subcutaneous injection into immuno-deficient mice were extracted at 7-day intervals up to 21 day interval. Paraffin-embedded tissue sections were evaluated by H&E staining and immunohistochemistry for specific markers of three germ layer cell types and epithelial stem cells in oral tissues. ResultsDuring iPS cell-derived teratoma development, ectodermal cells emerged first, followed by the appearance of mesodermal and endodermal cells. The teratomas contained various types of epithelia, including epithelial masses, pseudostratified epithelium, simple epithelium and stratified epithelium. As teratoma development progressed, the epithelia matured. p63 and K14 were strongly expressed in epithelial masses and in the basal layer of pseudostratified and stratified epithelium. CD49f was expressed in all types of epithelia observed, and intense expression was observed in both the basal layer and luminal surface of pseudostratified and stratified epithelium. ConclusionsiPS cell-derived teratoma is a useful model for study of epithelial development, and it may provide significant information regarding oral epithelial tissue regeneration.

Emdogain® in carcinogenesis: a systematic review of in vitro studies

Emdogain is a commercial product of unknown composition and is clinically used to induce periodontal regeneration. This study aims to review current knowledge of the in vitro effects of Emdogain on oral tissues and, in particular, factors related to carcinoma. A systematic approach was used to review studies from the Embase and Pubmed databases; a total of 76 studies were included. These comprised in vitro studies of the cytokines in, or regulated by, Emdogain and assays designed to study the effects of EMD on human cells in oral tissues or malignant cells. Several studies have shown that EMD regulates the proliferation, migration, adhesion, gene expression, and cytokine production of (pre-)osteoblasts, periodontal fibroblasts, and gingival fibroblasts. However, the effects of EMD on malignant oral cells are not well understood. EMD seems to have broad regulatory effects on malignant cells and on several carcinoma-related factors. Evidence suggests that patients with premalignant or malignant mucosal lesions should not be treated with EMD.

Mast cells and oral inflammation.

Mast cells are mobile granule-containing secretory cells that are distributed preferentially about the microvascular endothelium in oral mucosa and dental pulp. The enzyme profile of mast cells in oral tissues resembles that of skin, with most mast cells expressing the serine proteases tryptase and chymase. Mast cells in oral tissues contain the pro-inflammatory cytokine tumour necrosis factor-alpha in their granules, and release of this promotes leukocyte infiltration during evolving inflammation in several conditions, including lichen planus, gingivitis, pulpitis, and periapical inflammation, through induction of endothelial-leukocyte adhesion molecules. Mast cell synthesis and release of other mediators exerts potent immunoregulatory effects on other cell types, while several T-lymphocyte-derived cytokines influence mast cell migration and mediator release. Mast cell proteases may contribute to alterations in basement membranes in inflammation in the oral cavity, such as the disruptions that allow cytotoxic lymphocytes to enter the epithelium in oral lichen planus. A close relationship exists among mast cells, neural elements, and laminin, and this explains the preferential distribution of mast cells in tissues. Mast cells are responsive to neuropeptides and, through their interaction with neural elements, form a neural immune network with Langerhans cells in mucosal tissues. This facilitates mast cell degranulation in response to a range of immunological and non-immunological stimuli. Because mast cells play a pivotal role in inflammation, therapies that target mast cell functions could have value in the treatment of chronic inflammatory disorders in the oral cavity.