Critical roles of adherens junctions in diseases of the oral mucosa

The oral cavity is directly exposed to a variety of environmental stimuli and contains a diverse microbiome that continuously interacts with the oral epithelium. Therefore, establishment and maintenance of the barrier function of the oral mucosa is of paramount importance for its function and for the body's overall health. The adherens junction is a cell-cell adhesion complex that is essential for epithelial barrier function. Although a considerable body of work has associated barrier disruption with oral diseases, the molecular underpinnings of these associations have not been equally investigated. This is critical, since adherens junction components also possess significant signaling roles in the cell, in addition to their architectural ones. Here, we summarize current knowledge involving adherens junction components in oral pathologies, such as cancer and oral pathogen-related diseases, while we also discuss gaps in the knowledge and opportunities for future investigation of the relationship between adherens junctions and oral diseases.

A novel junctional epithelial cell line, mHAT-JE01, derived from incisor epithelial cells

OBJECTIVES

Junctional epithelium (JE) connects the tooth surface and gingival epithelium and adheres directly to the tooth enamel. JE plays an important role as a barrier preventing the invasion of exogenous bacteria and substances. However, the cellular characteristics of this epithelium have not been adequately described, because no useful in vitro experimental model exists for JE.

METHODS

We generated a novel JE cell line, mHAT-JE01, using naturally immortalized dental epithelium derived from incisor labial cervical cells and by selecting cells that adhered to apatite. mHAT-JE01 was characterized by immunohistochemistry and quantitative reverse transcription-polymerase chain reaction and compared with the gingival epithelial cell line, mOE-PE01.

RESULTS

The mHAT-JE01 cells had a higher capacity for producing JE-specific markers than oral mucous epithelial cells. In addition, the presence of lipopolysaccharides from Porphyromonas gingivalis downregulated the expression of JE protein markers in mHAT-JE01 cells.

CONCLUSIONS

This cell line is stable and presents the opportunity to characterize JE efficiently, which is essential for the prevention and treatment of periodontal disease.

Breaking the Gingival Barrier in Periodontitis

The break of the epithelial barrier of gingiva has been a subject of minor interest, albeit playing a key role in periodontal pathology, transitory bacteraemia, and subsequent systemic low-grade inflammation (LGI). The significance of mechanically induced bacterial translocation in gingiva (e.g., via mastication and teeth brushing) has been disregarded despite the accumulated knowledge of mechanical force effects on tight junctions (TJs) and subsequent pathology in other epithelial tissues. Transitory bacteraemia is observed as a rule in gingival inflammation, but is rarely observed in clinically healthy gingiva. This implies that TJs of inflamed gingiva deteriorate, e.g., via a surplus of lipopolysaccharide (LPS), bacterial proteases, toxins, Oncostatin M (OSM), and neutrophil proteases. The inflammation-deteriorated gingival TJs rupture when exposed to physiological mechanical forces. This rupture is characterised by bacteraemia during and briefly after mastication and teeth brushing, i.e., it appears to be a dynamic process of short duration, endowed with quick repair mechanisms. In this review, we consider the bacterial, immune, and mechanical factors responsible for the increased permeability and break of the epithelial barrier of inflamed gingiva and the subsequent translocation of both viable bacteria and bacterial LPS during physiological mechanical forces, such as mastication and teeth brushing.

Junctional epithelium and hemidesmosomes: Tape and rivets for solving the "percutaneous device dilemma" in dental and other permanent implants

The percutaneous device dilemma describes etiological factors, centered around the disrupted epithelial tissue surrounding non-remodelable devices, that contribute to rampant percutaneous device infection. Natural percutaneous organs, in particular their extracellular matrix mediating the "device"/epithelium interface, serve as exquisite examples to inspire longer lasting long-term percutaneous device design. For example, the tooth's imperviousness to infection is mediated by the epithelium directly surrounding it, the junctional epithelium (JE). The hallmark feature of JE is formation of hemidesmosomes, cell/matrix adhesive structures that attach surrounding oral gingiva to the tooth's enamel through a basement membrane. Here, the authors survey the multifaceted functions of the JE, emphasizing the role of the matrix, with a particular focus on hemidesmosomes and their five main components. The authors highlight the known (and unknown) effects dental implant - as a model percutaneous device - placement has on JE regeneration and synthesize this information for application to other percutaneous devices. The authors conclude with a summary of bioengineering strategies aimed at solving the percutaneous device dilemma and invigorating greater collaboration between clinicians, bioengineers, and matrix biologists.

Characterization of junctional structures in the gingival epithelium as barriers against bacterial invasion

BACKGROUND AND OBJECTIVE

Adherens junctions (AJs) and tight junctions (TJs) are known to play a crucial role in maintaining the physical barrier function of the epithelium. Here, we aimed to characterize the distribution of AJs and TJs throughout the gingival epithelium and to obtain insights into the physiological importance of these junctional structures.

METHODS

Sections of mouse gingival tissue were examined using transmission electron microscopy (TEM) and bio-high voltage electron microscopy tomography. The gingival sections were stained for E-cadherin and JAM-A as markers of AJs and TJs, respectively, and examined using confocal microscopy and lattice structured illumination microscopy. Bacteria within the gingival epithelium were examined using in situ hybridization.

RESULTS

Junctional structures, including desmosomes, AJs, and TJs, were observed throughout the gingival epithelium. The expression levels of E-cadherin were particularly low in the granular/keratinized layers of the oral epithelium (OE), while extremely low JAM-A levels were detected in the granular/keratinized layers of the sulcular epithelium (SE). The three-dimensional rendering of the junctional structures revealed that both AJs and TJs in the gingival epithelium formed discontinuous short bands or patches. Interestingly, strong bacterial signals were observed at the granular/keratinized layers of both SE and OE, but a few bacteria were detected within the junctional epithelium (JE) and the basal/spinous layers of the SE and OE.

CONCLUSIONS

AJs and TJs form a discontinuous barrier throughout paracellular passage in the gingival epithelium; nevertheless, they seem to play an important role in defending against invading bacteria.

The rationale and potential for using Lactobacillus in the management of periodontitis

Periodontitis refers to a wide range of the inflammatory conditions of supporting dental structures. For some patients with periodontitis, antibacterial agents are needed as an adjuvant to mechanical debridement treatments and oral hygiene maintenance. However, the widespread use of broad-spectrum antibiotics for the prophylaxis and treatment of periodontal infections results in the emergence of resistant pathogens. Therefore, probiotics have become markedly interesting to researchers as a potentially safe alternative to periodontal treatment and maintenance. Probiotics have been used in medicine for decades and extensively applied to the treatment of inflammatory diseases through the modulation of microbial synergy and other mechanisms. A growing amount of evidence has shown that using Lactobacillus strains for oral cavity maintenance could improve periodontal health. In this study, we reviewed studies showing proof of the inhibitory effects of Lactobacillus species on periodontal inflammation. We also explored the rationale and potential for using Lactobacillus species in the management of periodontitis.

Probiotics-Mediated Bioconversion and Periodontitis

Novel bioactive metabolites have been developed through a bioconversion of dairy products or other foods using probiotics isolated from dairy products or other fermented foods. These probiotics-mediated bioconversion (PMB) metabolites show antioxidant, anti-inflammatory, antimicrobial, epithelial barrier, and anticancer activities. In addition, the effect of PMB metabolites in periodontitis is recently reported in several studies. Periodontitis is a chronic inflammatory disease caused by infections, and the tooth support tissue is destroyed. Common treatments for periodontitis include scaling and root planning with systemic antibiotics. However, the overuse of antibiotics has led to the emergence of drug-resistant microorganisms and disturbs the beneficial bacteria, including lactobacilli in the oral cavity. For this reason, PMB metabolites, such as fermented milk, have been suggested as substitutes for antibiotics to reduce periodontitis. This paper reviews the recent studies on the correlation between periodontitis and PMB metabolites and classifies the efficacy of major PMB metabolites for periodontitis. The review suggests that PMB is effective for periodontitis, and further studies are needed to confirm the therapeutic effect of PMB metabolites on periodontitis.

Sema4C modulates the migration of primary tumor-associated lymphatic endothelial cells via an ERK-mediated pathway

Although lymphatic endothelial cells (LECs) serve a positive role in tumor lymphatic metastasis, the regulation of LECs undergoing migration similar to that of tumor cells remains poorly understood. A previous study revealed that semaphorin 4C (Sema4C) could be a marker of LECs in cervical cancer. Thus, the present study aimed to understand the mechanism via which Sema4C could promote the development of tumor-associated characteristics in LECs in cervical cancer. Primary tumor-associated LECs (TLECs) were distinguished from cervical cancer by flow cytometry. The promigratory ability was assessed using the Transwell assay. Lentivirus infection was used to alter the expression of Sema4C in TLECs. Confocal laser scanning was used to determine the infection efficiency of lentivirus infection. Sema4C/ERK/E-cadherin pathway was measured by reverse transcription-quantitative PCR and western blotting. The co-localization of Sema4C and the lymphatic marker lymphatic vessel endothelial hyaluronan receptor 1 was verified. Primary tumor-associated LECs (TLECs) were isolated from a mouse xenograft cervical tumor model. It was revealed that overexpressing Sema4C stimulated the migratory ability of TLECs, downregulated E-cadherin expression and stimulated ERK phosphorylation, whereas knocking down Sema4C had the opposite effects. The treatment of PD98059 (ERK inhibitor) blocked the pro-migratory ability of TLECs, which indicated a dependence on the ERK signaling pathway. It was identified that the Sema4C/ERK/E-cadherin pathway may be critical for the migration of TLECs, which may promote lymph node metastasis. Therefore, Sema4C could be a promising target for the treatment of cervical cancer with lymphatic metastasis.

Current Study of RhoA and Associated Signaling Pathways in Gastric Cancer

Gastric cancer (GC) is the fourth-most common cancer in the world, with an estimated 1.034 million new cases in 2015, and the third-highest cause of cancer deaths, estimated at 785,558, in 2014. Early diagnosis and treatment greatly affect the survival rate in patients with GC: the 5-year survival rate of early GC reaches 90%-95%, while the mortality rate significantly increases if GC develops to the late stage. Recently, studies for the role of RhoA in the diseases have become a hot topic, especially in the development of tumors. A study found that RhoA can regulate actin polymerization, cell adhesion, motor-myosin, cell transformation, and the ability to participate in the activities of cell movement, proliferation, migration, which are closely related to the invasion and metastasis of tumor cells. However, the specific role of RhoA in tumor cells remains to be studied. Therefore, our current study aimed to briefly review the role of RhoA in GC, especially for its associated signaling pathways involved in the GC progression.

Mas receptor activation attenuates allergic airway inflammation via inhibiting JNK/CCL2-induced macrophage recruitment

BACKGROUND

Defective absorption of acute allergic airway inflammation is involved in the initiation and development of chronic asthma. After allergen exposure, there is a rapid recruitment of macrophages around the airways, which promote acute inflammatory responses. The Ang-(1-7)/Mas receptor axis reportedly plays protective roles in various tissue inflammation and remodeling processes in vivo. However, the exact role of Mas receptor and their underlying mechanisms during the pathology of acute allergic airway inflammation remains unclear.

OBJECTIVE

We investigated the role of Mas receptor in acute allergic asthma and explored its underlying mechanisms in vitro, aiming to find critical molecules and signal pathways.

METHODS

Mas receptor expression was assessed in ovalbumin (OVA)-induced acute asthmatic murine model. Then we estimated the anti-inflammatory role of Mas receptor in vivo and explored expressions of several known inflammatory cytokines as well as phosphorylation levels of MAPK pathways. Mas receptor functions and underlying mechanisms were studied further in the human bronchial epithelial cell line (16HBE).

RESULTS

Mas receptor expression decreased in acute allergic airway inflammation. Multiplex immunofluorescence co-localized Mas receptor and EpCAM, indicated that Mas receptor may function in the bronchial epithelium. Activating Mas receptor through AVE0991 significantly alleviated macrophage infiltration in airway inflammation, accompanied with down-regulation of CCL2 and phosphorylation levels of MAPK pathways. Further studies in 16HBE showed that AVE0991 pre-treatment inhibited LPS-induced or anisomycin-induced CCL2 increase and THP-1 macrophages migration via JNK pathways.

CONCLUSION

Our findings suggested that Mas receptor activation significantly attenuated CCL2 dependent macrophage recruitments in acute allergic airway inflammation through JNK pathways, which indicated that Mas receptor, CCL2 and phospho-JNK could be potential targets against allergic airway inflammation.

Candida albicans and candidalysin in inflammatory disorders and cancer

As our understanding of mycology progresses, the impact of fungal microbes on human health has become increasingly evident. Candida albicans is a common commensal fungus that gives rise to local and systemic infections, particularly in immunocompromised patients where it can result in mortality. However, C. albicans has also been quietly linked with a variety of inflammatory disorders, to which it has traditionally been considered incidental; recent studies may now provide new aspects of these relationships for further consideration. This review provides a novel perspective on the impact of C. albicans and its peptide toxin, candidalysin, on human health, exploring their contributions to pathology within a variety of diseases.

Analysis of DNA methylation of E-cadherin and p16ink4a in oral lichen planus/oral lichenoid lesions

OBJECTIVES

Epigenetic phenomena are changes in gene expression not involving the DNA sequence. DNA methylation is a major occurrence underlying epigenetic changes in human cells. Although aberrant DNA methylation is well documented in malignant lesions, limited information has been shown on the involvement of DNA methylation in oral lichen planus and oral lichenoid lesions (OLP). The present study aimed to investigate DNA methylation of E-cadherin and p16 in OLP, and compare the findings with those in non-inflamed gingiva (Non), radicular cyst (RC), and oral squamous cell carcinoma (SCC).

MATERIALS AND METHODS

Paraffin-embedded surgical biopsy specimens were sliced, DNA was extracted, bisulfite treatment was applied, and methylation-specific polymerase chain reaction was performed. Immunohistochemistry was performed to observe the relative expression patterns of these genes.

RESULTS

E-cadherin was hypermethylated in OLP (p < 0.01), SCC (p < 0.01), and RC (p < 0.05), when compared with Non; DNA hypermethylation was confirmed in OLP and SCC when compared to Non and RC. Hypermethylation of p16^ink4a was observed only in SCC (p < 0.01).

CONCLUSION

DNA methylation levels of E-cadherin and p16^ink4a were significantly higher in OLP than in normal tissues, and may be associated with the pathogenesis and progression of the disease.

Harnessing biomolecules for bioinspired dental biomaterials

Dental clinicians have relied for centuries on traditional dental materials (polymers, ceramics, metals, and composites) to restore oral health and function to patients. Clinical outcomes for many crucial dental therapies remain poor despite many decades of intense research on these materials. Recent attention has been paid to biomolecules as a chassis for engineered preventive, restorative, and regenerative approaches in dentistry. Indeed, biomolecules represent a uniquely versatile and precise tool to enable the design and development of bioinspired multifunctional dental materials to spur advancements in dentistry. In this review, we survey the range of biomolecules that have been used across dental biomaterials. Our particular focus is on the key biological activity imparted by each biomolecule toward prevention of dental and oral diseases as well as restoration of oral health. Additional emphasis is placed on the structure-function relationships between biomolecules and their biological activity, the unique challenges of each clinical condition, limitations of conventional therapies, and the advantages of each class of biomolecule for said challenge. Biomaterials for bone regeneration are not reviewed as numerous existing reviews on the topic have been recently published. We conclude our narrative review with an outlook on the future of biomolecules in dental biomaterials and potential avenues of innovation for biomaterial-based patient oral care.

Microbial and Host Factors That Affect Bacterial Invasion of the Gingiva

Periodontitis is a chronic inflammation of the periodontium caused by the loss of homeostasis between subgingival biofilms and susceptible hosts. Bacterial invasion into the gingival tissue and persistent infection are major events that lead to chronic inflammation. The intratissue bacterial communities are as complex as the subgingival biofilms and can also form biofilm-like structures, which will serve as a reservoir for local and systemic infections. The epithelium forms physical, chemical, and immunological barriers against invading microbes. Nevertheless, many bacterial species can invade the gingival epithelium through transcellular and paracellular pathways. In addition, both genetic and environmental factors of the hosts can affect epithelial barrier functions and thus bacterial invasion of the gingiva. In this review, current evidence for the bacterial invasion of the gingival tissue in periodontitis has been summarized, and the microbial and host factors that determine bacterial invasion of the gingiva have been reviewed.

Lactobacillus-Derived Bioactive Metabolites for the Regulation of Periodontal Health: Evidences to Clinical Setting

Background: Gut microbiota plays a pivotal role in regulating host metabolism that affects the systemic health. To date, several studies have confirmed the fact that microbiota interacts with host, modulating immunity, controlling the homeostasis environment, and maintaining systemic condition. Recent studies have focused on the protective function of poly unsaturated fatty acids, 10-oxo-trans-11-oxadecenoic acid (KetoC) and 10-hydroxy-cis-12-octadecenoic acid (HYA), generated by gut microbiota on periodontal disease. Nevertheless, the mechanism remains unclear as investigations are limited to in vivo and in vitro studies. In this present review, we found that the administration of metabolites, KetoC and HYA, by a probiotic gut microbiota Lactobacillus plantarum from linoleic acid is found to inhibit the oxidation process, possess an antimicrobial function, and prevent the inflammation. These findings suggest the promising use of functional lipids for human health. Conclusion: Protective modalities of bioactive metabolites may support periodontal therapy by suppressing bacterial dysbiosis and regulating periodontal homeostasis in the clinical setting.

JNK Signaling as a Key Modulator of Soft Connective Tissue Physiology, Pathology, and Healing

In healthy individuals, the healing of soft tissues such as skin after pathological insult or post injury follows a relatively predictable and defined series of cell and molecular processes to restore tissue architecture and function(s). Healing progresses through the phases of hemostasis, inflammation, proliferation, remodeling, and concomitant with re-epithelialization restores barrier function. Soft tissue healing is achieved through the spatiotemporal interplay of multiple different cell types including neutrophils, monocytes/macrophages, fibroblasts, endothelial cells/pericytes, and keratinocytes. Expressed in most cell types, c-Jun N-terminal kinases (JNK) are signaling molecules associated with the regulation of several cellular processes involved in soft tissue wound healing and in response to cellular stress. A member of the mitogen-activated protein kinase family (MAPK), JNKs have been implicated in the regulation of inflammatory cell phenotype, as well as fibroblast, stem/progenitor cell, and epithelial cell biology. In this review, we discuss our understanding of JNKs in the regulation of cell behaviors related to tissue injury, pathology, and wound healing of soft tissues. Using models as diverse as Drosophila, mice, rats, as well as human tissues, research is now defining important, but sometimes conflicting roles for JNKs in the regulation of multiple molecular processes in multiple different cell types central to wound healing processes. In this review, we focus specifically on the role of JNKs in the regulation of cell behavior in the healing of skin, cornea, tendon, gingiva, and dental pulp tissues. We conclude that while parallels can be drawn between some JNK activities and the control of cell behavior in healing, the roles of JNK can also be very specific modes of action depending on the tissue and the phase of healing.

Epidermal growth factor receptor signaling suppresses αvβ6 integrin and promotes periodontal inflammation and bone loss

In periodontal disease (PD), bacterial biofilms cause gingival inflammation, leading to bone loss. In healthy individuals, αvβ6 integrin in junctional epithelium maintains anti-inflammatory transforming growth factor-β1 (TGF-β1) signaling, whereas its expression is lost in individuals with PD. Bacterial biofilms suppress β6 integrin expression in cultured gingival epithelial cells (GECs) by attenuating TGF-β1 signaling, leading to an enhanced pro-inflammatory response. In the present study, we show that GEC exposure to biofilms induced activation of mitogen-activated protein kinases and epidermal growth factor receptor (EGFR). Inhibition of EGFR and ERK stunted both the biofilm-induced ITGB6 suppression and IL1B stimulation. Furthermore, biofilm induced the expression of endogenous EGFR ligands that suppressed ITGB6 and stimulated IL1B expression, indicating that the effects of the biofilm were mediated by autocrine EGFR signaling. Biofilm and EGFR ligands induced inhibitory phosphorylation of the TGF-β1 signaling mediator Smad3 at S208. Overexpression of a phosphorylation-defective mutant of Smad3 (S208A) reduced the β6 integrin suppression. Furthermore, inhibition of EGFR signaling significantly reduced bone loss and inflammation in an experimental PD model. Thus, EGFR inhibition may provide a target for clinical therapies to prevent inflammation and bone loss in PD.

Vitamin D maintains E-cadherin intercellular junctions by downregulating MMP-9 production in human gingival keratinocytes treated by TNF-α

Purpose

Despite the well-known anti-inflammatory effects of vitamin D in periodontal health, its mechanism has not been fully elucidated. In the present study, the effect of vitamin D on strengthening E-cadherin junctions (ECJs) was explored in human gingival keratinocytes (HGKs). ECJs are the major type of intercellular junction within the junctional epithelium, where loose intercellular junctions develop and microbial invasion primarily occurs.

Methods

HOK-16B cells, an immortalized normal human gingival cell line, were used for the study. To mimic the inflammatory environment, cells were treated with tumor necrosis factor-alpha (TNF-α). Matrix metalloproteinases (MMPs) in the culture medium were assessed by an MMP antibody microarray and gelatin zymography. The expression of various molecules was investigated using western blotting. The extent of ECJ development was evaluated by comparing the average relative extent of the ECJs around the periphery of each cell after immunocytochemical E-cadherin staining. Vitamin D receptor (VDR) expression was examined via immunohistochemical analysis.

Results

TNF-α downregulated the development of the ECJs of the HGKs. Dissociation of the ECJs by TNF-α was accompanied by the upregulation of MMP-9 production and suppressed by a specific MMP-9 inhibitor, Bay 11-7082. Exogenous MMP-9 decreased the development of ECJs. Vitamin D reduced the production of MMP-9 and attenuated the breakdown of ECJs in the HGKs treated with TNF-α. In addition, vitamin D downregulated TNF-α-induced nuclear factor kappa B (NF-κB) signaling in the HGKs. VDR was expressed in the gingival epithelium, including the junctional epithelium.

Conclusions

These results suggest that vitamin D may avert TNF-α-induced downregulation of the development of ECJs in HGKs by decreasing the production of MMP-9, which was upregulated by TNF-α. Vitamin D may reinforce ECJs by downregulating NF-κB signaling, which is upregulated by TNF-α. Strengthening the epithelial barrier may be a way for vitamin D to protect the periodontium from bacterial invasion.

Mitochondrial electron transport chain, ROS generation and uncoupling (Review)

The mammalian mitochondrial electron transport chain (ETC) includes complexes I-IV, as well as the electron transporters ubiquinone and cytochrome c. There are two electron transport pathways in the ETC: Complex I/III/IV, with NADH as the substrate and complex II/III/IV, with succinic acid as the substrate. The electron flow is coupled with the generation of a proton gradient across the inner membrane and the energy accumulated in the proton gradient is used by complex V (ATP synthase) to produce ATP. The first part of this review briefly introduces the structure and function of complexes I-IV and ATP synthase, including the specific electron transfer process in each complex. Some electrons are directly transferred to O₂ to generate reactive oxygen species (ROS) in the ETC. The second part of this review discusses the sites of ROS generation in each ETC complex, including sites I_F and I_Q in complex I, site II_F in complex II and site III_Qo in complex III, and the physiological and pathological regulation of ROS. As signaling molecules, ROS play an important role in cell proliferation, hypoxia adaptation and cell fate determination, but excessive ROS can cause irreversible cell damage and even cell death. The occurrence and development of a number of diseases are closely related to ROS overproduction. Finally, proton leak and uncoupling proteins (UCP_S) are discussed. Proton leak consists of basal proton leak and induced proton leak. Induced proton leak is precisely regulated and induced by UCPs. A total of five UCPs (UCP1-5) have been identified in mammalian cells. UCP1 mainly plays a role in the maintenance of body temperature in a cold environment through non-shivering thermogenesis. The core role of UCP2-5 is to reduce oxidative stress under certain conditions, therefore exerting cytoprotective effects. All diseases involving oxidative stress are associated with UCPs.

FOXF2 inhibits proliferation, migration, and invasion of Hela cells by regulating Wnt signaling pathway

This article was aimed to study the FOXF2 effects on cervical cancer. Tumor tissues and adjacent tissues of 41 cervical cancer patients were collected. Human endometrial epithelial cells (hEEC) and Hela cells were cultured. FOXF2 expression vector and its empty vector were transfected into Hela cells, and named as pcDNA 3.1-FOXF2 group and Vector group, respectively. Hela cells without any treatment were set as Blank group. qRT-PCR was used to detect mRNA expression. Nude mouse xenograft assay was performed to test Hela cells proliferation ability in vivo. FOXF2 and β-catenin positive cell numbers were detected by immunohistochemistry. Protein expression was analyzed by Western blot. Cells migration and invasion were conducted by Transwell. Tumor tissues and Hela cells FOXF2 expression were lower than that in adjacent tissues and hEEC (P<0.01). Low FOXF2 expression predicted poor outcomes of cervical cancer patients. Compared with Blank group and Vector group, Hela cells of pcDNA 3.1-FOXF2 group were with higher FOXF2 expression, lower OD₄₉₅ value, migrated and invaded cells, higher E-cadherin expression, lower Vimentin and Snail expression, smaller tumor volume in nude mice, lower c-Myc, CyclinDl, MMP9, Lgr5, and nuclear β-catenin expression (all P<0.01). FOXF2 inhibits Hela cells proliferation, migration, and invasion through regulating Wnt signaling pathway.

The Role of Reactive Oxygen Species and Autophagy in Periodontitis and Their Potential Linkage

Periodontitis is a chronic inflammatory disease that causes damage to periodontal tissues, which include the gingiva, periodontal ligament, and alveolar bone. The major cause of periodontal tissue destruction is an inappropriate host response to microorganisms and their products. Specifically, a homeostatic imbalance between reactive oxygen species (ROS) and antioxidant defense systems has been implicated in the pathogenesis of periodontitis. Elevated levels of ROS acting as intracellular signal transducers result in autophagy, which plays a dual role in periodontitis by promoting cell death or blocking apoptosis in infected cells. Autophagy can also regulate ROS generation and scavenging. Investigations are ongoing to elucidate the crosstalk mechanisms between ROS and autophagy. Here, we review the physiological and pathological roles of ROS and autophagy in periodontal tissues. The redox-sensitive pathways related to autophagy, such as mTORC1, Beclin 1, and the Atg12-Atg5 complex, are explored in depth to provide a comprehensive overview of the crosstalk between ROS and autophagy. Based on the current evidence, we suggest that a potential linkage between ROS and autophagy is involved in the pathogenesis of periodontitis.

Porphyromonas gingivalis suppresses invasion of Fusobacterium nucleatum into gingival epithelial cells

Invasion of periodontal pathogens into periodontal tissues is an important step that can cause tissue destruction in periodontal diseases. Porphyromonas gingivalis is a keystone pathogen and its gingipains are key virulence factors. Fusobacterium nucleatum is a bridge organism that mediates coadhesion of disease-causing late colonizers such as P. gingivalis and early colonizers during the development of dental biofilms. The aim of this study was to investigate how P. gingivalis, in particular its gingipains, influences the invasion of coinfecting F. nucleatum into gingival epithelial cells. When invasion of F. nucleatum was analyzed after 4 h of infection, invasion of F. nucleatum was suppressed in the presence of P. gingivalis compared with during monoinfection. However, coinfection with a gingipain-null mutant of P. gingivalis did not affect invasion of F. nucleatum. Inhibition of PI3K reduced invasion of F. nucleatum. P. gingivalis inactivated the PI3K/AKT pathway, which was also dependent on gingipains. Survival of intracellular F. nucleatum was promoted by P. gingivalis with Arg gingipain mutation. The results suggest that P. gingivalis, in particular its gingipains, can affect the invasion of coinfecting F. nucleatum through modulating intracellular signaling of the host cells.

Substrate roughness induces the development of defective E-cadherin junctions in human gingival keratinocytes

Purpose

The entry of bacteria or harmful substances through the epithelial seal of human gingival keratinocytes (HGKs) in the junctional epithelium (JE) is blocked by specialized intercellular junctions such as E-cadherin junctions (ECJs). However, the influence of roughened substrates, which may occur due to apical migration of the JE, root planing, or peri-implantitis, on the development of the ECJs of HGKs remains largely unknown.

Methods

HGKs were cultured on substrates with varying levels of roughness, which were prepared by rubbing hydrophobic polystyrene dishes with silicon carbide papers. The activity of c-Jun N-terminal kinase (JNK) was inhibited with SP600125 or by transfection with JNK short hairpin RNA. The development of intercellular junctions was analyzed using scanning electron microscopy or confocal laser scanning microscopy after immunohistochemical staining of the cells for E-cadherin. The expression level of phospho-JNK was assessed by immunoblotting.

Results

HGKs developed tight intercellular junctions devoid of wide intercellular gaps on smooth substrates and on rough substrates with low-nanometer dimensions (average roughness [Ra]=121.3±13.4 nm), although the ECJs of HGKs on rough substrates with low-nanometer dimensions developed later than those of HGKs on smooth substrates. In contrast, HGKs developed short intercellular junctions with wide intercellular gaps on rough substrates with mid- or high-nanometer dimensions (Ra=505.3±115.3 nm, 867.0±168.6 nm). Notably, the stability of the ECJs was low on the rough substrates, as demonstrated by the rapid destruction of the cell junction following calcium depletion. Inhibition of JNK activity promoted ECJ development in HGKs. JNK was closely associated with cortical actin in the regulation of ECJs in HGKs.

Conclusions

These results indicate that on rough substrates with nanometer dimensions, the ECJs of HGKs develop slowly or defectively, and that this effect can be reversed by inhibiting JNK.

JNK-associated scattered growth of YD-10B oral squamous carcinoma cells while maintaining the epithelial phenotype

Cell scattering of epithelial carcinoma cancer cells is one of the critical event in tumorigenesis. Cells losing epithelial cohesion detach from aggregated epithelial cell masses and may migrate to fatal organs through metastasis. The present study investigated the molecular mechanism by which squamous cell carcinoma cells grow scattered at the early phase of transformation while maintaining the epithelial phenotype. We studied YD-10B cells, which are established from human oral squamous cell carcinoma, because the cells grow scattered without the development of E-cadherin junctions (ECJs) under routine culture conditions despite the high expression of functional E-cadherin. The functionality of their E-cadherin was demonstrated in that YD-10B cells developed ECJs, transiently or persistently, when they were cultured on substrates coated with a low amount of fibronectin or to confluence. The phosphorylation of JNK was up-regulated in YD-10B cells compared with that in human normal oral keratinocyte cells or human squamous cell carcinoma cells, which grew aggregated along with well-organized ECJs. The suppression of JNK activity induced the aggregated growth of YD-10B cells concomitant with the development of ECJs. These results indicate for the first time that inherently up-regulated JNK activity induces the scattered growth of the oral squamous cell carcinoma cells through down-regulating the development of ECJ despite the expression of functional E-cadherin, a hallmark of the epithelial phenotype.