The role of pyroptosis in inflammatory diseases.

Programmed cell death has crucial roles in the physiological maturation of an organism, the maintenance of metabolism, and disease progression. Pyroptosis, a form of programmed cell death which has recently received much attention, is closely related to inflammation and occurs via canonical, non-canonical, caspase-3-dependent, and unclassified pathways. The pore-forming gasdermin proteins mediate pyroptosis by promoting cell lysis, contributing to the outflow of large amounts of inflammatory cytokines and cellular contents. Although the inflammatory response is critical for the body's defense against pathogens, uncontrolled inflammation can cause tissue damage and is a vital factor in the occurrence and progression of various diseases. In this review, we briefly summarize the major signaling pathways of pyroptosis and discuss current research on the pathological function of pyroptosis in autoinflammatory diseases and sterile inflammatory diseases.

Effect of access cavities on the biomechanics of mandibular molars: a finite element analysis.

INTRODUCTION: This study aimed to predict the fracture resistance of a mandibular first molar (MFM) with diverse endodontic cavities using finite element analysis (FEA). METHODS: Five experimental finite element models representing a natural tooth (NT) and 4 endodontically treated MFMs were generated. Treated MFM models were with a traditional endodontic cavity (TEC) and minimally invasive endodontic (MIE) cavities, including guided endodontic cavity (GEC), contracted endodontic cavity (CEC) and truss endodontic cavity (TREC). Three loads were applied, simulating a maximum bite force of 600 N (N) vertically and a normal masticatory force of 225 N vertically and laterally. The distributions of von Mises (VM) stress and maximum VM stress were calculated. RESULTS: The maximum VM stresses of the NT model were the lowest under normal masticatory forces. In endodontically treated models, the distribution of VM stress in GEC model was the most similar to NT model. The maximum VM stresses of the GEC and CEC models under different forces were lower than those of TREC and TEC models. Under vertical loads, the maximum VM stresses of the TREC model were the highest, while under the lateral load, the maximum VM stress of the TEC model was the highest. CONCLUSION: The stress distribution of tooth with GEC was most like NT. Compared with TECs, GECs and CECs may better maintain fracture resistance, TRECs, however, may have a limited effect on maintenance of the tooth resistance.

Corrigendum to "Nav1.7 via Promotion of ERK in the Trigeminal Ganglion Plays an Important Role in the Induction of Pulpitis Inflammatory Pain".

[This corrects the article DOI: 10.1155/2019/6973932.].

Nav1.7 via Promotion of ERK in the Trigeminal Ganglion Plays an Important Role in the Induction of Pulpitis Inflammatory Pain.

The trigeminal ganglion (TG) refers to sensory neurons bodies that innervate the spinal cord and peripheral axons that innervate teeth. The tetrodotoxin-sensitive sodium (NA) channels (Nav1.7) play important roles in the pathophysiology of pain. In this study, we investigated the TG expression of Nav1.7 and extracellular signal-regulated kinase (ERK) in a rat model of pulpitis to explore the correlation between these channels and inflammatory pain. Pulpitis was confirmed by hematoxylin-eosin staining. In this study, we demonstrated that the reflex of rats to mechanical stimulation increases after pulp exposure and that the exposed rat molar pulp can upregulate the expression of Nav1.7 and ERK in the rat TG. Three days after rat pulp exposure, the expression levels of the two ion channels in the TG increased. TG target injection of PF04856264, a Nav1.7 inhibitor, dose-dependently increased the mechanical pain threshold and was able to inhibit ERK expression. TG target injection of PD98059, an ERK inhibitor, dose-dependently increased the mechanical pain threshold. These factors simultaneously resulted in the highest production. In this study, with the established link to inflammatory pain, we found that Nav1.7 and ERK both play important roles in the induction of inflammatory pain caused by pulpitis. We also found a correlation between the expression levels of Nav1.7 and ERK and the degree of inflammatory pain. Furthermore, ERK signaling pathways were promoted by the Nav1.7 in TG after pulpitis.

Wnt-GSK3ß/ß-Catenin Regulates the Differentiation of Dental Pulp Stem Cells into Bladder Smooth Muscle Cells.

Smooth muscle cell- (SMC-) based tissue engineering provides a promising therapeutic strategy for SMC-related disorders. It has been demonstrated that human dental pulp stem cells (DPSCs) possess the potential to differentiate into mature bladder SMCs by induction with condition medium (CM) from bladder SMC culture, in combination with the transforming growth factor-ß1 (TGF-ß1). However, the molecular mechanism of SMC differentiation from DPSCs has not been fully uncovered. The canonical Wnt signaling (also known as Wnt/ß-catenin) pathway plays an essential role in stem cell fate decision. The aim of this study is to explore the regulation via GSK3ß and associated downstream effectors for SMC differentiation from DPSCs. We characterized one of our DPSC clones with the best proliferation and differentiation abilities. This stem cell clone has shown the capacity to generate a smooth muscle layer-like phenotype after an extended differentiation duration using the SMC induction protocol we established before. We further found that Wnt-GSK3ß/ß-catenin signaling is involved in the process of SMC differentiation from DPSCs, as well as a serial of growth factors, including TGF-ß1, basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), hepatocyte growth factor (HGF), platelet-derived growth factor-homodimer polypeptide of B chain (BB) (PDGF-BB), and vascular endothelial growth factor (VEGF). Pharmacological inhibition on the canonical Wnt-GSK3ß/ß-catenin pathway significantly downregulated GSK3ß phosphorylation and ß-catenin activation, which in consequence reduced the augmented expression of the growth factors (including TGF-ß1, HGF, PDGF-BB, and VEGF) as well as SMC markers (especially myosin) at a late stage of SMC differentiation. These results suggest that the canonical Wnt-GSK3ß/ß-catenin pathway contributes to DPSC differentiation into mature SMCs through the coordination of different growth factors.

Hey1 functions as a positive regulator of odontogenic differentiation in odontoblast­lineage cells.

Substantial evidence has indicated that Notch and bone morphogenetic protein (BMP) signaling may regulate odontoblastic differentiation. Hairy/enhancer­of­split related with YRPW motif 1 (Hey1), a downstream target gene of Notch and BMP signaling, is expressed in dental pulp tissues and has been demonstrated to be responsible for osteoblast mineralization. The aim of this study was to investigate the effects of Hey1 on odontoblast differentiation. The results of the study demonstrated that Hey1 expression in odontoblast­lineage cells (OLCs) was upregulated by stimulation of osteoblastic/odontoblastic differentiation medium containing ascorbic acid, ß­glycerol phosphate and dexamethasone. Furthermore, stable Hey1­overexpressing cells expressed higher levels of dentin sialophosphoprotein (DSPP) and exhibited higher mineralization capabilities following stimulation by differentiation medium. Furthermore, RNA interference­mediated knockdown of Hey1 downregulated the expression levels of DSPP in OLCs stimulated by differentiation medium. Taken together, the findings indicate that Hey1 may be a positive regulator of odontoblastic differentiation. The present study broadens the understanding of odontoblast differentiation and biomineralization.

Clinical effect of a manual toothbrush with tapered filaments on dental plaque and gingivitis reduction.

PURPOSE: To evaluate the anti-plaque efficacy (Study 1) and the anti-gingivitis efficacy (Study 2) of a manual toothbrush with tapered bristles compared to marketed control manual toothbrushes. METHODS: Studies 1 and 2 were independent, randomized and controlled, single-center, examiner-blind clinical trials in generally healthy adults. Study 1 included a 2-day acclimation period, followed by a 5-day twice daily toothbrushing test phase with the assigned brush. Baseline and Day 5 pre- and post-brushing plaque levels were assessed via Turesky Modified Quigley-Hein Plaque Index (TMQHPI). In Study 2, subjects with existing gingivitis brushed with their assigned toothbrush twice daily for 4 weeks. Gingivitis was measured using the Mazza Modification of the Papillary Bleeding Index at Baseline and Weeks 2 and 4. In both trials, subjects were randomly assigned to either the manual toothbrush with tapered bristles (Oral-B Super Thin Indicator toothbrush, OM159) or the marketed control (Study 1: Oral-B Complete Clean & Sensitive toothbrush; Study 2: Crest Pro-Health Complete 7 Brush 35 toothbrush) for use with a regular fluoridated dentifrice. RESULTS: 40 (Study 1) and 63 (Study 2) subjects were randomized in each trial. In Study 1, both the tapered bristle and marketed control brushes provided significant (P< 0.0001) mean whole mouth plaque reductions at Day 1 and Day 5 post-brushing relative to pre-brushing as measured via TMQPHI, with no between-brush significant differences. Both groups showed a significant reduction in Day 5 post-brushing mean plaque scores versus Day 1 pre- brushing mean plaque scores (P< 0.0001), but the reductions were not significantly different between groups (P= 0.4274). In Study 2, both the tapered bristle brush and the marketed control brush produced significant (P< 0.0001) reductions in both gingivitis and number of gingival bleeding sites at both Weeks 2 and 4 versus baseline. At Week 4, the tapered filament toothbrush group showed 8.6% less gingivitis (P= 0.0017) and 33.4% fewer bleeding sites (P= 0.0030) versus the control brush. All toothbrushes were well-tolerated. CLINICAL SIGNIFICANCE: Twice daily customary use of a manual toothbrush with tapered bristles provided clinically meaningful plaque and gingivitis reduction benefits.

The Regulatory Effects of Long Noncoding RNA-ANCR on Dental Tissue-Derived Stem Cells.

Long noncoding RNAs (lncRNA) have been recognized as important regulators in diverse biological processes, such as transcriptional regulation, stem cell proliferation, and differentiation. Previous study has demonstrated that lncRNA-ANCR (antidifferentiation ncRNA) plays a key role in regulating the proliferation and osteogenic differentiation of periodontal ligament stem cells (PDLSCs). However, little is known about the role of ANCR in regulating other types of dental tissue-derived stem cells (DTSCs) behaviours (including proliferation and multiple-potential of differentiation). In this study, we investigated the regulatory effects of lncRNA-ANCR on the proliferation and differentiation (including osteogenic, adipogenic, and neurogenic differentiation) of DTSCs, including dental pulp stem cells (DPSCs), PDLSCs, and stem cells from the apical papilla (SCAP) by downregulation of lncRNA-ANCR. We found that downregulation of ANCR exerted little effect on proliferation of DPSCs and SCAP but promoted the osteogenic, adipogenic, and neurogenic differentiation of DTSCs. These data provide an insight into the regulatory effects of long noncoding RNA-ANCR on DTSCs and indicate that ANCR is a very important regulatory factor in stem cell differentiation.

Pleurocidin congeners demonstrate activity against Streptococcus and low toxicity on gingival fibroblasts.

OBJECTIVES: Fish epidermal antimicrobial peptides, such as pleurocidin, are cathelicidins with broad-spectrum antimicrobial activity against gram negative and gram-positive bacteria, as well as fungi. In the current study, we attempted to optimize peptide bioactivity by sequence modification and assess the antimicrobial activities. METHODS: Fifteen pleurocidin analogues were designed, and the efficacy of pleurocidin congeners against common cariogenic microorganisms was tested; furthermore, we performed a preliminary study of the antimicrobial mechanism. We assayed the minimal inhibitory concentration (MIC), minimal bactericide concentration (MBC) and bactericidal kinetics to determine the cell killing activity. Scanning electron microscopy (SEM) was used to observe the bacterial membrane after treatment with congeners' peptides. Human gingival fibroblasts (HGFs) were also used in toxicity studies. RESULTS: The MIC and MBC results indicated that peptide congeners had different antimicrobial activities against the tested oral strains. Toxicity studies indicated that several congener peptides had little effect on human gingival fibroblasts (HGFs) with 5min of in vitro treatment. CONCLUSION: Our findings suggested that several pleurocidin congeners had the antimicrobial effect against Streptococcus mutans, Streptococcus sanguinis and Streptococcus sobrinus.

Dentin regeneration by stem cells of apical papilla on injectable nanofibrous microspheres and stimulated by controlled BMP-2 release.

UNLABELLED: The aim of this study was to investigate the effects of PLLA nanofibrous microspheres (NF-MS) as a cell delivery carrier in combination with controlled release of BMP-2 from PLGA microspheres on the induction of odontogenic differentiation of human stem cells of apical papilla (SCAP). Injectable NF-MS, which mimic the physical architecture of collagen fibers on the nano scale, were fabricated by combining thermally-induced phase separation techniques with an emulsification process. SCAP cultured in a monolayer or cultured on NF-MS in spinner flasks were treated with 100ng/ml BMP-2 in vitro. Odontogenic differentiation was characterized by measuring alkaline phosphatase activity, odontogenic gene expression levels, calcium content, and dentin sialophosphoprotein accumulation. The results demonstrated that BMP-2 enhanced human SCAP odontogenic differentiation both in monolayer culture and on 3D NF-MS in spinner flask culture in vitro. We also developed and tested a system combining NF-MS with controlled BMP-2 release for dentin regeneration in vivo. The results indicate that controlled release of BMP-2 promoted more mineralization and osteodentin formation compared to a BSA-releasing control in a dose-dependent and time-dependent manner. In summary, the NF-MS combined with controlled release of BMP-2 provides an excellent microenvironment for SCAP to regenerate dentin tissue. STATEMENT OF SIGNIFICANCE: Tooth lesion and loss affect masticatory efficiency, speaking function, facial aesthetics and even psychological health. Current treatments depend on "inert" restorative materials, which do not have the healing capacity and may lead to the failure of the restorations over a long term. The aim of this study was to develop an injectable biomaterial and desired growth factor delivery system to support stem cells for mineralized dental tissue regeneration. The study showed that novel injectable and biodegradable nanofibrous microspheres and controlled release of BMP-2 synergistically induce the odontogenic differentiation of human stem cells from the apical papilla and mineralized tissue regeneration, demonstrating the potential of living dental tissue repair.

Bladder Smooth Muscle Cells Differentiation from Dental Pulp Stem Cells: Future Potential for Bladder Tissue Engineering.

Dental pulp stem cells (DPSCs) are multipotent cells capable of differentiating into multiple cell lines, thus providing an alternative source of cell for tissue engineering. Smooth muscle cell (SMC) regeneration is a crucial step in tissue engineering of the urinary bladder. It is known that DPSCs have the potential to differentiate into a smooth muscle phenotype in vitro with differentiation agents. However, most of these studies are focused on the vascular SMCs. The optimal approaches to induce human DPSCs to differentiate into bladder SMCs are still under investigation. We demonstrate in this study the ability of human DPSCs to differentiate into bladder SMCs in a growth environment containing bladder SMCs-conditioned medium with the addition of the transforming growth factor beta 1 (TGF-ß1). After 14 days of exposure to this medium, the gene and protein expression of SMC-specific marker (α-SMA, desmin, and calponin) increased over time. In particular, myosin was present in differentiated cells after 11 days of induction, which indicated that the cells differentiated into the mature SMCs. These data suggested that human DPSCs could be used as an alternative and less invasive source of stem cells for smooth muscle regeneration, a technology that has applications for bladder tissue engineering.

Nanofibrous spongy microspheres for the delivery of hypoxia-primed human dental pulp stem cells to regenerate vascularized dental pulp.

Dental pulp infection and necrosis are widespread diseases. Conventional endodontic treatments result in a devitalized and weakened tooth. In this work, we synthesized novel star-shaped polymer to self-assemble into unique nanofibrous spongy microspheres (NF-SMS), which were used to carry human dental pulp stem cells (hDPSCs) into the pulp cavity to regenerate living dental pulp tissues. It was found that NF-SMS significantly enhanced hDPSCs attachment, proliferation, odontogenic differentiation and angiogenesis, as compared to control cell carriers. Additionally, NF-SMS promoted vascular endothelial growth factor (VEGF) expression of hDPSCs in a 3D hypoxic culture. Hypoxia-primed hDPSCs/NF-SMS complexes were injected into the cleaned pulp cavities of rabbit molars for subcutaneous implantation in mice. After 4 weeks, the hypoxia group significantly enhanced angiogenesis inside the pulp chamber and promoted the formation of ondontoblast-like cells lining along the dentin-pulp interface, as compared to the control groups (hDPSCs alone group, NF-SMS alone group, and hDPSCs/NF-SMS group pre-cultured under normoxic conditions). Furthermore, in an in situ dental pulp repair model in rats, hypoxia-primed hDPSCs/NF-SMS were injected to fully fill the pulp cavity and regenerate pulp-like tissues with a rich vasculature and a histological structure similar to the native pulp. STATEMENT OF SIGNIFICANCE: Vascularization is key to the regeneration of many vital tissues. However, it is challenging to create a suitable microenvironment for stem cells to regenerate vascularized tissue structure. This manuscript reports a novel star-shaped block copolymer that self-assembles into unique nanofibrous spongy microspheres, which as an injectable scaffold recapitulate the cell-cell and cell-matrix interactions in development. Using a clinically-relevant surgical procedure and a hypoxic treatment, the nanofibrous spongy microspheres were used to deliver stem cells and successfully regenerate dental pulp with a rich vasculature and a complex histologic structure similar to that of the native dental pulp. The novel microspheres can likely be used to regenerate many other vascularized tissues.

Nanofibrous spongy microspheres enhance odontogenic differentiation of human dental pulp stem cells.

Dentin regeneration is challenging due to its complicated anatomical structure and the shortage of odontoblasts. In this study, a novel injectable cell carrier, nanofibrous spongy microspheres (NF-SMS), is developed for dentin regeneration. Biodegradable and biocompatible poly(l-lactic acid)-block-poly(l-lysine) are synthesized and fabricated into NF-SMS using self-assembly and thermally induced phase separation techniques. It is hypothesized that NF-SMS with interconnected pores and nanofibers can enhance the proliferation and odontogenic differentiation of human dental pulp stem cells (hDPSCs), compared to nanofibrous microspheres (NF-MS) without pore structure and conventional solid microspheres (S-MS) with neither nanofibers nor pore structure. During the first 9 d in culture, hDPSCs proliferate significantly faster on NF-SMS than on NF-MS or S-MS (p < 0.05). Following in vitro odontogenic induction, all the examined odontogenic genes (alkaline phosphatase content, osteocalcin, bone sialoprotein, collagen 1, dentin sialophosphoprotein (DSPP)), calcium content, and DSPP protein content are found significantly higher in the NF-SMS group than in the control groups. Furthermore, 6 weeks after subcutaneous injection of hDPSCs and microspheres into nude mice, histological analysis shows that NF-SMS support superior dentin-like tissue formation compared to NF-MS or S-MS. Taken together, NF-SMS have great potential as an injectable cell carrier for dentin regeneration.

Mechanisms that lead to the regulation of NLRP3 inflammasome expression and activation in human dental pulp fibroblasts.

BACKGROUND: The NLRP3 inflammasome plays an important role in the cellular defense against invading pathogens and is reported to be expressed in human dental pulp fibroblasts (HDPFs). However, the role of the NLRP3 inflammasome in HDPFs during pulpal infection and inflammation remains unclear. OBJECTIVES: To elucidate the function of the NLRP3 inflammasome and the mechanisms that lead to its expression and activation in HDPFs. METHODS: The test model used lipopolysaccharide (LPS) and adenosine triphosphate (ATP) to simulate an inflammatory environment. Lentiviral vectors encoding short hairpin RNAs were used to knock down NLRP3 and caspase-1 in HDPFs. Specific inhibitors were used to determine whether the toll-like receptor 4 (TLR4), myeloid differentiating factor 88 (MyD88), or nuclear factor-kappa B (NF-κB) pathways were involved in the regulation of NLRP3 expression. Reactive oxygen species (ROS) production was measured by fluorescent microscopy and flow cytometry using the total ROS/superoxide detection kit. Gene and protein expression were quantified by real-time polymerase chain reaction and Western blot, while cytokine release was measured by an enzyme-linked immunosorbent assay. RESULTS: LPS up-regulated NLRP3 and IL-1ß expression while ATP induced the activation of caspase-1 and the release of IL-1ß in LPS-primed HDPFs. The knockdown of NLRP3 or caspase-1 expression significantly inhibited IL-1ß secretion. Pretreatment with a TLR4 inhibitor, a MyD88 inhibitory peptide, or an I Kappa B alpha (IκBα) phosphorylation inhibitor significantly inhibited LPS-induced NLRP3 and IL-1ß expression. ATP potently promoted ROS generation in HDPFs; N-acetyl cysteine inhibited ROS production, caspase-1 activation and IL-1ß secretion induced by ATP. CONCLUSIONS: Our results demonstrated that the NLRP3 inflammasome in HDPFs is crucial for IL-1ß secretion in response to LPS plus ATP. LPS engaged the TLR4/MyD88/NF-κB pathway to enhance NLRP3 and pro-IL-1ß expression in HDPFs. ATP promoted the generation of ROS and activated the NLRP3 inflammasome in a ROS-dependent manner.

Four-rooted permanent maxillary first and second molars in a northwestern Chinese population.

OBJECTIVES: To detect the incidence and anatomic features of 4-rooted permanent maxillary molars in a northwestern Chinese population by using cone-beam computed tomography (CBCT). DESIGN: A total of 725 Chinese patients with well-developed maxillary permanent first and/or second molars were examined by using CBCT. The number of roots and canals, shape, location, and division level of the roots were evaluated. Four-rooted maxillary first and second molars were classified according to modified Versiani's classification. The root length and cross-sectional diameters of 4-rooted molars were measured by the software Galileos Implant 1.7 (SICAT GmbH & Co. KG, Bonn, Germany). One way analysis of variance followed by a Newman-Keuls post hoc test was used to compare the groups in relation to the root length and diameters (P = 0.05). RESULTS: Among 1365 maxillary first molars, only one tooth had four separated roots, whereas in second molars, 12 out of 1226 teeth (0.98%) exhibited an extra root; the incidences were 1.28% (7/549) for males and 0.74% (5/677) for females. All 4-rooted molars observed were unilateral. Out of a total of thirteen 4-rooted maxillary molars, six exhibited the type I root form, four exhibited the type II root form and one exhibited the type III root form; a type IV category (two molars) was added to Versiani's classification, which described maxillary molars with three buccal roots. A transitional root form between the typical 3-rooted form and double palatal roots was observed in six cases of 3-rooted molars. Measurements of root size showed that the diameter of the distopalatal roots was significantly larger than the extra mesiopalatal roots (P < 0.01). CONCLUSION: The prevalence of the 4-rooted maxillary first and second molars in the Chinese population is low. They usually occurred unilaterally, and the shape, location and size of the four roots may be variable.

Melatonin attenuates inflammation of acute pulpitis subjected to dental pulp injury.

Acute pulpitis (AP), one of the most common diseases in the endodontics, usually causes severe pain to the patients, which makes the search for therapeutic target of AP essential in clinic. Toll-like receptor 4 (TLR4) signaling is widely involved in the mechanism of pulp inflammation, while melatonin has been reported to have an inhibition for a various kinds of inflammation. We hereby studied whether melatonin can regulate the expression of TLR4/NF-ĸB signaling in the pulp tissue of AP and in human dental pulp cells (HDPCs). Two left dental pulps of the adult rat were drilled open to establish the AP model, and the serum levels of melatonin and pro-inflammatory cytokines, including interleukin 1ß (IL-1ß), interleukin 18 (IL-18) and tumor necrosis factor α (TNF-α), were assessed at 1, 3 and 5 d post injury. At the same time points, the expression of TLR4 signaling in the pulp was explored by quantitative real-time PCR and immunohistochemistry. The AP rats were administered an abdominal injection of melatonin to assess whether melatonin rescued AP and TLR4/NF-ĸB signaling. Dental pulp injury led to an approximately five-day period acute pulp inflammation and necrosis in the pulp and a significant up-regulation of IL-1ß, IL-18 and TNF-α in the serum. ELISA results showed that the level of melatonin in the serum decreased due to AP, while an abdominal injection of melatonin suppressed the increase in serum cytokines and the percentage of necrosis at the 5 d of the injured pulp. Consistent with the inflammation in AP rats, TLR4, NF-ĸB, TNF-α and IL-1ß in the pulp were increased post AP compared with the baseline expression. And melatonin showed an inhibition on TLR4/NF-ĸB signaling as well as IL-1ß and TNF-α production in the pulp of AP rats. Furthermore, melatonin could also regulate the expression of TLR4/NF-ĸB signaling in LPS-stimulated HDPCs. These data suggested that dental pulp injury induced AP and reduced the serum level of melatonin and that supplementation with melatonin may have a protective effect on AP by modulating TLR4/NF-ĸB signaling in the pulp and in pulp cells.

Activation of the NLRP3/caspase-1 inflammasome in human dental pulp tissue and human dental pulp fibroblasts.

The NLRP3/caspase-1 inflammasome pathway plays an important role in cellular immune defence against bacterial infection; however, its function in human dental pulp tissue and human dental pulp fibroblasts remains poorly understood. We demonstrate that NLRP3 protein expression occurs to a greater extent in pulp tissue with irreversible pulpitis than in normal pulp tissue and in tissue with reversible pulpitis. Caspase-1 is present in its active (cleaved) form only in pulp tissue with irreversible pulpitis. NLRP3 and caspase-1 are expressed in the odontoblast layers in normal human dental pulp tissue, whereas in inflamed pulp tissue, the odontoblast layers are disrupted and dental pulp cells are positive for NLRP3 and caspase-1. Additionally, we investigate the role of the NLRP3/caspase-1 inflammasome pathway in human dental pulp fibroblasts and show that ATP activates the P2X7 receptor on the cell membrane triggering K(+) efflux and inducing the gradual recruitment of the membrane pore pannexin-1. Extracellular lipopolysaccharide is able to penetrate the cytosol and activate NLRP3. Furthermore, the low intracellular K(+) concentration in the cytosol triggers reactive oxygen species generation, which also induces the NLRP3 inflammasome. Thus, the NLRP3/caspase-1 pathway has a biological role in the innate immune response mounted by human dental pulp fibroblasts.

Down-regulated non-coding RNA (lncRNA-ANCR) promotes osteogenic differentiation of periodontal ligament stem cells.

OBJECTIVE: Our studies aimed to figure out how anti-differentiation noncoding RNA (ANCR) regulates the proliferation and osteogenic differentiation of periodontal ligament stem cells (PDLSCs). DESIGN: In this study, we used lentivirus infection to down-regulate the expression of ANCR in PDLSCs. Then we compared the proliferation of control cells and PDLSC/ANCR-RNAi cells by Cell Counting Kit-8. And the osteogenic differentiation of control cells and PDLSC/ANCR-RNAi cells were evaluated by Alkaline phosphatase (ALP) activity quantification and Alizarin red staining. WNT inhibitor was used to analyze the relationship between ANCR and canonical WNT signalling pathway. The expression of osteogenic differentiation marker mRNAs, DKK1, GSK3-ß and ß-catenin were evaluated by qRT-PCR. RESULTS: The results showed that down-regulated ANCR promoted proliferation of PDLSCs. Down-regulated ANCR also promoted osteogenic differentiation of PDLSCs by up-regulating osteogenic differentiation marker genes. After the inhibition of canonical WNT signalling pathway, the osteogenic differentiation of PDLSC/ANCR-RNAi cells was inhibited too. qRT-PCR results also demonstrated that canonical WNT signalling pathway was activated for ANCR-RNAi on PDLSCs during the procedure of proliferation and osteogenic induction. CONCLUSIONS: These results indicated that ANCR was a key regulator of the proliferation and osteogenic differentiation of PDLSCs, and its regulating effects was associated with the canonical WNT signalling pathway, thus offering a new target for oral stem cell differentiation studies that could also facilitate oral tissue engineering.

Antibacterial peptide nisin: a potential role in the inhibition of oral pathogenic bacteria.

Although the antimicrobial peptide nisin has been extensively studied in the food industry for decades, its application in the oral cavity remains to develop and evaluate its feasibility in treating oral common diseases. Nisin is an odorless, colorless, tasteless substance with low toxicity and with antibacterial activities against Gram-positive bacteria. These biologic properties may establish its use in promising products for oral diseases. This article summarizes the antibacterial efficiency of nisin against pathogenic bacteria related to dental caries and root canal infection and discusses the combination of nisin and common oral drugs.