Background and Objective
After tooth extraction, the extraction socket undergoes several steps of soft and hard tissue healing. The healing process of the extraction socket is modulated by a range of ...signaling factors and biochemical agents. It has been reported that resveratrol, a polyphenolic compound, exhibits various biological effects, including anti‐inflammatory, anti‐carcinogenic, antioxidant, and anti‐aging effects, and protects cardiovascular and bone tissues. In this study, we examined the cellular effects of resveratrol on human periodontal ligament (hPDL) cells and osteoblast‐like (MC3T3‐E1) cells and evaluated the bone‐healing capacity of tooth extraction sockets in mice.
Material and Methods
Resveratrol was applied to hPDL and MC3T3‐E1 cells to detect cell proliferation and alkaline phosphatase (ALP) activity, and qPCR was employed to understand the gene expression level in vitro. For in vivo experiment, six‐week‐old C57BL/6 male mice were randomly divided into control (n = 15) and experimental (n = 15) groups and maxillary first molars were extracted by surgery. Experimental groups received 50‐µM resveratrol on extraction sockets and analyzed the degree of new bone formation.
Results
Treatment of hPDL and MC3T3‐E1 cells with resveratrol increased the cell proliferation and ALP activity and enhanced the expression of ALP, BMP‐2, BMP‐4, and OC genes. Resveratrol enhanced new bone formation in the lingual extraction socket in mice.
Conclusion
These results suggest that resveratrol increases the cellular physiology of PDL and osteoblast including their proliferation and differentiation and may play an important role in bone‐healing capacity after tooth extraction.
The alveolar bone process is the thickened ridge of bone that bears the teeth and is known to have dynamic functional interactions with surrounding tissues. However, the detailed morphological ...changes that occur during alveolar bone process development and the underlying molecular mechanisms behind this morphogenesis have not been elucidated. In this study, we examined the detailed morphological changes of the alveolar bone process during mouse development using HE and MTC staining. In addition, we evaluated the precise localization pattern of various signaling molecules involved in blood vessel formation including CD31, α-SMA, VEGF, periostin, and TGF-β. Innervation of the alveolar bone process was examined following injection of the nerve terminal dye AM1-43. The morphological and immunohistochemical data suggested that there is an intimate relationship between alveolar bone process development and blood vessel formation. To more closely examine the role of blood vessels in alveolar bone process formation, we microinjected mice with a clinically available anti-VEGF antibody, bevacizumab, at PN5 and analyzed the effects 5 days later. Compared to the control animals, anti-VEGF treated animals showed a disruption of the integration of bony tissues to form the alveolar bone process structures, which should contain the periodontal ligaments. Based on these data, we conclude that specific morphogenesis of the alveolar bone process is closely associated with blood vessel formation.
Epithelial differentiation is thought to be determined by mesenchymal components during embryogenesis. In mice, palatal mucosa showed the region-specific keratinization pattern along antero-posterior ...axis. However, developmental mechanisms involved in oral mucosa differentiation with fine tuning of keratinization are not elucidated yet. To reveal this developmental mechanism, first, we conducted tissue recombination assay of the palate at E16 for 2 days which revealed that epithelial differentiation with specific localization of CK10 is modulated by mesenchymal components. Based on the results, we propose that mesenchymal signaling would determine the presumptive fate of developing palatal epithelium in spatiotemporal manner. Genome-wide screening analysis using laser micro-dissection to collect spatiotemporal specific molecules between anterior and posterior palate suggested
Meox2
in the posterior mesenchymal tissue to be a candidate regulator controlling epithelial differentiation. To examine the detailed spatiotemporal function of
Meox2
, we employed in vitro organ cultivation with the loss- and gain-of-function studies at E14.5 for 2 and 4 days, respectively. Our results suggest that posteriorly expressed
Meox2
modulates non-keratinized epithelial differentiation through complex signaling regulations in mice palatogenesis.
•Chronic tongue injury model using silk suture was first established and described.•Our model revealed region specific localization of MPO, MMP2, TNFα, NGF and TRPV1.•Prolonged injury may contribute ...altered neuronal function on antero-ventral tongue.•Our model is useful to unravel pathological mechanism of neuropathic pain like BMS.
Chronic injury in tongue causes the variety of reactions in the oral cavity, frequently leading to its functional and structural disintegrity including inflammation and sensory dysfunction, but its detailed profiles were not elucidated yet. One of the chronically injured tongue such as tongue piercing, as a pathological aspect, is currently popular among younger people but may be associated with severe side effects, leading to pathophysiological complications. However, the pathophysiological aspects and related cellular and molecular mechanisms underlying tongue injury are not clearly understood.
In this study, we designed an experimental model system using C57BL/6 male mice that mimics a chronically injured situation by penetrating the middle part of tongue with silk suture. After 5 and 10 days mice were sacrificed and tongues were collected and processed for histological evaluation and immunohistochemistry.
We found that the anterior tongue showed localization of neuro-inflammatory signaling molecules such as myeloperoxidase (MPO), matrix metalloproteinase 2 (MMP2), tumor necrosis factor-α (TNF-α), nerve growth factor, and transient receptor potential cation channel subfamily V member 1 (TRPV1) without any apparent inflammation in temporal manner. In addition, the signal for AM1-43, an activity-dependent nerve terminal probe, decreased within the fungiform papillae on the anterior tongue after injury.
These results implied that the distinct localizations of inflammatory cytokines and neurotrophin would contribute altered sensory function in anterior tongue following the chronic injury. Our study indicates the possible pathophysiologic mechanism underlying neuro-inflammation following chronically injury of tongue. In addition, it could be cautiously postulated that mechanical injury should be avoided to prevent chronic pain disorders from being triggered.
After palatal fusion, the dorsal and ventral epithelia of the palatal shelf differentiate into the nasal and oral mucosa, respectively. The tissue-specific differentiation of palatal epithelia along ...the dorsal–ventral axis is regulated by the signaling molecules expressed in the underlying mesenchyme. Thus, as in many other epithelial organs, differentiation relies on epithelial–mesenchymal interactions. To screen for region-specific mesenchymal signaling molecules that determine the fate of the palatal epithelia, we employed a laser microdissection (LMD) method. LMD allowed us to collect region-specific mesenchymal tissues at E13, prior to palatal fusion and the development of distinct dorsal and ventral epithelial morphology. Genome-wide screening was performed on the tissues collected using LMD to identify candidate mesenchymal signaling molecules. The microarray results were validated using real-time quantitative (qPCR) and in situ hybridization methods. The developmental role and interactions of the candidate genes were evaluated in in vitro-cultivated E13 palates using an anti-sense oligodeoxynucleotide (AS-ODN)-based loss-of-function approach. Apparent changes in the expression patterns of Runt-related transcription factor 2 (Runx2) and LIM homeobox 8 (Lhx8) were observed after knocking down each gene. Knock-down of Runx2 and Lhx8 also altered the immunolocalization pattern of cytokeratin18 (CK18), an established marker for nasal epithelium. These results were confirmed using Runx2 heterozygote mice. The mesenchymal signaling molecules Runx2 and Lhx8, which possess region-specific expression patterns along the dorsoventral axis, functionally interact to regulate the cellular and molecular characteristics of dorsal and ventral epithelia, suggesting that mesenchymal signaling molecules determine the dorsoventral fate of epithelial structures in the developing palate.
Teraspanin transmembrane protein, Perp (P53 apoptosis effector related to PMP22), which is found in the plasma membrane as a component of the desmosome, is reported to be involved in the ...morphogenesis of the epithelium and the enamel formation of the incisor. However, its expression pattern and signaling regulation during molar development have not been elucidated in detail. We have examined the precise expression patterns of Perp in developing lower molars and employed the knock-down of Perp by antisense oligodeoxynucleotide treatment during in vitro organ cultivation at embryonic day 13 to define the precise developmental function of Perp. Perp was expressed mainly in the dental lamina and stellate reticulum regions at the bud and cap stages. After Perp knock-down, the tooth germ showed disruption of the dental lamina and stellate reticulum with altered apoptosis and proliferation. The changed expression levels of related signaling molecules from the enamel knot and desmosome were evaluated by real-time quantitative polymerase chain reaction. A renal capsule transplantation method was employed to examine the effects of Perp knock-down on molar crown development. Ultrastructural observations revealed that enamel was deposited more densely in an irregular pattern in the cusp region, and that dentin was hypo-mineralized after Perp knock-down at the cap stage. Thus, Perp might play important roles in the formation and integration of stellate reticulum, dental lamina structure and enamel formation through signaling interactions with the enamel knot and desmosome-related signaling molecules at the cap stage of lower molar development.
Adenomatosis polyposis coli downregulated 1 (APCDD1), a negative regulator of Wnt signaling, was examined to understand detailed mechanisms underlying Wnt signaling tooth development. In situ ...hybridization showed that
Apcdd1
was expressed in the condensed mesenchyme at the bud stage, and in the inner enamel epithelium (IEE), including enamel knot (EK) at the cap stage. In vitro organ cultivation by using
Apcdd1
antisense oligodeoxynucleotides was performed at E13.5 for 2 days to define the developmental functions of APCDD1 during tooth development. Analysis of histogenesis and cellular events such as cell adhesion, proliferation, apoptosis and epithelial rearrangement after
Apcdd1
knockdown showed altered morphogenesis of the tooth germ with decreased cell proliferation and altered localization of cell adhesion molecules. Actin filament staining and 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI) labeling of IEE cells showed that
Apcdd1
knockdown enhanced epithelial rearrangement in the IEE and EK. To understand the precise signaling regulations of Apcdd1, we evaluated the altered expression patterns of signaling molecules, related with Wnt and enamel knot signalings using RT-qPCR. Tooth germs at cap stage were transplanted into the kidney capsules and were allowed to develop into calcified teeth for 3 weeks.
Apcdd1
knockdown increased the number of ectopic cusps on the mesial side of the tooth. Our results suggested that APCDD1 modulates the gene expression of Wnt- and EK-related signaling molecules at the cap stage of tooth development, and is involved in tooth cusp patterning by modulating the epithelial rearrangement in the IEE.
In mice, tongue epithelial differentiation is mainly regulated by the interactions among various signalling molecules including Fgf signalling pathways. However, the subsequent signalling modulations ...for epithelial maturation, initiated by Fgf signalling, remain to be elucidated. Therefore, we employed an in vitro tongue organ cultivation system along with the applications of various pharmacological inhibitors against the intracellular signalling molecules of Fgf signalling pathways, including H89, LY294002, PD98059, and U0126. Following treatments with LY294002 and H89, inhibitors for PI3K and PKA, respectively, the decreased thickness of the tongue epithelium was observed along with the alteration in cell proliferative and apoptotic patterns. Meanwhile, cultivated tongues treated with MEK inhibitor U0126 or PD98059 showed significantly decreased cell proliferation in the tongue epithelium and the mesenchyme. Based on these results, we suggest that the tongue epithelium is differentiated into multiple epithelial cell layers via the PI3K and PKA pathways in tissue-specific manner during the epithelial-mesenchymal interactions.
Limited information is available regarding AmpC β-lactamase (ABL)-producing Enterobacteriaceae compared to extended-spectrum β-lactamase-producing enterobacteria. Since ABL-producing organisms are ...often resistant to multiple antimicrobial agents, therapeutic options against these pathogens are limited. Among 230 clinical Enterobacteriaceae isolates, 64 (27.8%) were found to produce ABL in our study. Escherichia coli (83.9%) was a predominant pathogen, followed by Citrobacter freundii (5.2%). A significant proportion of ABL-producing isolates (81.3%) were found to be multidrug resistant against commonly used antibiotics. Univariate analysis showed that prior history of taking antibiotics (odds ratio OR, 5.278; confidence interval CI, 2.838–9.817; p < 0.001) and being inpatients (OR, 4.587; CI, 2.132–9.9; p < 0.001) were associated with ABL positivity. Regular antimicrobial resistance surveillance for ABL-producing Enterobacteriaceae is warranted for proper antimicrobial treatment strategy and policy making due to ABL-positive infections. Keywords: AmpC β-lactamase, Enterobacteriaceae, Antibiotic resistance
