Dysregulation of CXCL1 Expression and Neutrophil Recruitment in Insulin Resistance and Diabetes-Related Periodontitis in Male Mice.

Insulin resistance and hyperglycemia are risk factors for periodontitis and poor wound healing in diabetes, which have been associated with selective loss of insulin activation of the PI3K/Akt pathway in the gingiva. This study showed that insulin resistance in the mouse gingiva due to selective deletion of smooth muscle and fibroblast insulin receptor (SMIRKO mice) or systemic metabolic changes induced by a high-fat diet (HFD) in HFD-fed mice exacerbated periodontitis-induced alveolar bone loss, preceded by delayed neutrophil and monocyte recruitment and impaired bacterial clearance compared with their respective controls. The immunocytokines, CXCL1, CXCL2, MCP-1, TNFα, IL-1ß, and IL-17A, exhibited delayed maximal expression in the gingiva of male SMIRKO and HFD-fed mice compared with controls. Targeted overexpression of CXCL1 in the gingiva by adenovirus normalized neutrophil and monocyte recruitment and prevented bone loss in both mouse models of insulin resistance. Mechanistically, insulin enhanced bacterial lipopolysaccharide-induced CXCL1 production in mouse and human gingival fibroblasts (GFs), via Akt pathway and NF-κB activation, which were reduced in GFs from SMIRKO and HFD-fed mice. These results provided the first report that insulin signaling can enhance endotoxin-induced CXCL1 expression to modulate neutrophil recruitment, suggesting CXCL1 as a new therapeutic direction for periodontitis or wound healing in diabetes. ARTICLE HIGHLIGHTS: The mechanism for the increased risks for periodontitis in the gingival tissues due to insulin resistance and diabetes is unclear. We investigated how insulin action in gingival fibroblasts modulates the progression of periodontitis in resistance and diabetes. Insulin upregulated the lipopolysaccharide-induced neutrophil chemoattractant, CXCL1, production in gingival fibroblasts via insulin receptors and Akt activation. Enhancing CXCL1 expression in the gingiva normalized diabetes and insulin resistance-induced delays in neutrophils recruitment and periodontitis. Targeting dysregulation of CXCL1 in fibroblasts is potentially therapeutic for periodontitis and may also improve wound healing in insulin resistance and diabetes.

Characterization and Study of Gene Expression Profiles of Human Periodontal Mesenchymal Stem Cells in Spheroid Cultures by Transcriptome Analysis.

A spheroid is known as a three-dimensional culture model, which better simulates the physiological conditions of stem cells. This study is aimed at identifying genes specifically expressed in spheroid-cultured human periodontal ligament mesenchymal stem cells (hPDLMSCs) using RNA-seq analysis to evaluate their functions. Transcriptome analysis was performed using spheroid and monolayer cultures of hPDLMSCs from four patients. Cluster and Gene Ontology analyses revealed that genes involved in cell-cell adhesion as well as the G2/M and G1/S transitions of mitotic cell cycles were strongly expressed in the monolayer culture group. However, genes involved in the negative regulation of cell proliferation, histone deacetylation, and bone morphogenetic protein signaling were strongly expressed in the spheroid culture group. We focused on the transcription factor nuclear receptor subfamily 4 group A member 2 (NR4A2) among the genes that were strongly expressed in the spheroid culture group and analyzed its function. To confirm the results of the transcriptome analysis, we performed real-time polymerase chain reaction and western blotting analyses. Interestingly, we found that the mRNA and protein expressions of NR4A2 were strongly expressed in the spheroid-cultured hPDLMSCs. Under osteogenic differentiation conditions, we used siRNA to knock down NR4A2 in spheroid-cultured hPDLMSCs to verify its role in osteogenesis. We found that NR4A2 knockdown significantly increased the levels of mRNA expression for osteogenesis-related genes alkaline phosphatase (ALP), Osteopontin (OPN), and type 1 collagen (COL1) (Student's paired t-test, p < 0.05). ALP activity was also significantly increased when compared to the negative control group (Student's paired t-test, p < 0.05). Additionally, spheroid-cultured hPDLMSCs transfected with siNR4A2 were cultured for 12 days, resulting in the formation of significantly larger calcified nodules compared to the negative control group (Student's paired t-test, p < 0.05). On the other hand, NR4A2 knockdown in hPDLMSC spheroid did not affect the levels of chondrogenesis and adipogenesis-related genes under chondrogenic and adipogenic conditions. These results suggest that NR4A2 negatively regulates osteogenesis in the spheroid culture of hPDLMSCs.

Mechanism of alveolar bone destruction in periodontitis - Periodontal bacteria and inflammation.

Periodontal disease is an inflammatory disease caused by periodontopathogenic bacteria, which eventually leads to bone tissue (alveolar bone) destruction as inflammation persists. Periodontal tissues have an immune system against the invasion of these bacteria, however, due to the persistent infection by periodontopathogenic bacteria, the host innate and acquired immunity is impaired, and tissue destruction, including bone tissue destruction, occurs. Osteoclasts are essential for bone destruction. Osteoclast progenitor cells derived from hematopoietic stem cells differentiate into osteoclasts. In addition, bone loss occurs when bone resorption by osteoclasts exceeds bone formation by osteoblasts. In inflammatory bone disease, inflammatory cytokines act on osteoblasts and receptor activator of nuclear factor-κB ligand (RANKL)-producing cells, resulting in osteoclast differentiation and activation. In addition to this mechanism, pathogenic factors of periodontal bacteria and mechanical stress activate osteoclasts and destruct alveolar bone in periodontitis. In this review, we focused on the mechanism of osteoclast activation in periodontitis and provide an overview based on the latest findings.

Correction to: RNA-sequencing reveals positional memory of multipotent mesenchymal stromal cells from oral and maxillofacial tissue transcriptomes.

An amendment to this paper has been published and can be accessed via the original article.

RNA-sequencing reveals positional memory of multipotent mesenchymal stromal cells from oral and maxillofacial tissue transcriptomes.

BACKGROUND: Multipotent mesenchymal stromal cells (MSCs) can be isolated from numerous tissues and are attractive candidates for therapeutic clinical applications due to their immunomodulatory and pro-regenerative capacity. Although the minimum criteria for defining MSCs have been defined, their characteristics are known to vary depending on their tissue of origin. RESULTS: We isolated and characterized human MSCs from three different bones (ilium (I-MSCs), maxilla (Mx-MSCs) and mandible (Md-MSCs)) and proceeded with next generation RNA-sequencing. Furthermore, to investigate the gene expression profiles among other cell types, we obtained RNA-seq data of human embryonic stem cells (ESCs) and several types of MSCs (periodontal ligament-derived MSCs, bone marrow-derived MSCs, and ESCs-derived MSCs) from the Sequence Reads Archive and analyzed the transcriptome profile. We found that MSCs derived from tissues of the maxillofacial region, such as the jaw bone and periodontal ligament, were HOX-negative, while those derived from other tissues were HOX-positive. We also identified that MSX1, LHX8, and BARX1, an essential regulator of craniofacial development, were strongly expressed in maxillofacial tissue-derived MSCs. Although MSCs may be divided into two distinct groups, the cells originated from over the neck or not, on the basis of differences in gene expression profile, the expression patterns of all CD antigen genes were similar among different type of MSCs, except for ESCs. CONCLUSIONS: Our findings suggest that MSCs from different anatomical locations, despite meeting general characterization criteria, have remarkable differences in gene expression and positional memory. Although stromal cells from different anatomical sources are generally categorized as MSCs, their differentiation potential and biological functions vary. We suggested that MSCs may retain an original tissue memory about the developmental process, including gene expression profiles. This could have an important impact when choosing an appropriate cell source for regenerative therapy using MSCs.

Associations of cytokine levels in gingival crevicular fluid of mobile teeth with clinical improvement after initial periodontal treatment.

Studies suggest that analysis of gingival crevicular fluid (GCF) is useful for evaluating periodontal status. In this study, clinical variables related to tooth mobility, and multiple cytokine levels in proximate GCF, were measured at four time points during initial periodontal treatment: before treatment (baseline), after supragingival scaling, after occlusal adjustment, and after scaling and root planing (SRP); 20 teeth from 13 patients with periodontitis were included. Baseline interleukin (IL)-10 level in GCF was significantly higher around teeth that showed substantial improvement in periodontal epithelial surface area (PESA) after SRP than around teeth without PESA improvement. IL-3 and IL-16 levels in GCF at baseline were significantly higher around teeth with a periodontal inflamed surface area (PISA) of 0 mm2 after SRP than around teeth without PISA improvement. In addition, baseline IL-7, IL-11, and IL-12p40 levels in GCF were significantly lower around teeth with decreased mobility after occlusal adjustment than around teeth without decreased mobility. These results suggest that pre-treatment cytokine levels in GCF are useful in predicting the effects of initial periodontal treatment.

Co-cultured spheroids of human periodontal ligament mesenchymal stem cells and vascular endothelial cells enhance periodontal tissue regeneration.

INTRODUCTION: Human periodontal ligament mesenchymal stem cells (hPDLMSCs) have been known that they play important roles in homeostasis and regeneration of periodontal tissues. Additionally, spheroids are superior to monolayer-cultured cells. We investigated the characteristics and potential of periodontal tissue regeneration in co-cultured spheroids of hPDLMSCs and human umbilical vein endothelial cells (HUVECs) in vitro and in vivo. METHODS: Co-cultured spheroids were prepared with cell ratios of hPDLMSCs: HUVECs = 1:1, 1:2, and 2:1, using microwell chips. Real-time polymerase chain reaction (PCR) analysis, Enzyme-Linked Immuno Sorbent Assay (ELISA), and nodule formation assay were performed to examine the properties of co-cultured spheroids. Periodontal tissue defects were prepared in the maxillary first molars of rats and subjected to transplantation assay. RESULTS: The expression levels of stemness markers, vascular endothelial growth factor (VEGF), osteogenesis-related genes were up-regulated in co-cultured spheroids, compared with monolayer and spheroid-cultured hPDLMSCs. The nodule formation was also increased in co-cultured spheroids, compared with monolayer and spheroid cultures of hPDLMSCs. Treatment with co-cultured spheroids enhanced new cementum formation after 4 or 8 weeks of transplantation, although there was no significant difference in the new bone formation between co-cultured spheroids and hPDLMSC spheroids. CONCLUSIONS: We found that co-cultured spheroids enhance the periodontal tissue regeneration. Co-cultured spheroids of hPDLMSCs and HUVECs may be a useful therapy that can induce periodontal tissue regeneration.

RNA sequencing for ligature induced periodontitis in mice revealed important role of S100A8 and S100A9 for periodontal destruction.

Periodontitis is an inflammatory disease caused by pathogenic oral microorganisms that induce the destruction of periodontal tissue. We sought to identify the relevant differentially expressed genes (DEGs) and clarify the mechanism underlying the rapid alveolar bone loss by using ligature-induced periodontitis in mice. A silk ligature was tied around the maxillary left second molar in 9-week-old C57BL/6 J male mice. In-vivo micro-CT analysis revealed that ligation induced severe bone loss. RNA-sequencing analysis, to examine host responses at 3 days post-ligation, detected 12,853 genes with fragments per kilobase of exon per million mapped reads ≥ 1, and 78 DEGs. Gene ontology term enrichment analysis revealed the expression profiles related to neutrophil chemotaxis and inflammatory responses were significantly enriched in the ligated gingiva. The expression levels of innate immune response-related genes, including S100a8 and S100a9, were significantly higher in the ligated side. S100A8 was strongly detected by immunohistochemistry at the attached epithelium in ligated sites. Inhibition of S100A8 and S100A9 expression revealed that they regulated IL1B and CTSK expression in Ca9-22 cells. Thus, innate immune response-related molecules might be associated with the burst-destruction of periodontal tissue in ligature-induced periodontitis. Especially, S100A8 and S100A9 may play an important role in alveolar bone resorption.

A systematic sequencing-based approach for microbial contaminant detection and functional inference.

BACKGROUND: Microbial contamination poses a major difficulty for successful data analysis in biological and biomedical research. Computational approaches utilizing next-generation sequencing (NGS) data offer promising diagnostics to assess the presence of contaminants. However, as host cells are often contaminated by multiple microorganisms, these approaches require careful attention to intra- and interspecies sequence similarities, which have not yet been fully addressed. RESULTS: We present a computational approach that rigorously investigates the genomic origins of sequenced reads, including those mapped to multiple species that have been discarded in previous studies. Through the analysis of large-scale synthetic and public NGS samples, we estimate that 1000-100,000 contaminating microbial reads are detected per million host reads sequenced by RNA-seq. The microbe catalog we established included Cutibacterium as a prevalent contaminant, suggesting that contamination mostly originates from the laboratory environment. Importantly, by applying a systematic method to infer the functional impact of contamination, we revealed that host-contaminant interactions cause profound changes in the host molecular landscapes, as exemplified by changes in inflammatory and apoptotic pathways during Mycoplasma infection of lymphoma cells. CONCLUSIONS: We provide a computational method for profiling microbial contamination on NGS data and suggest that sources of contamination in laboratory reagents and the experimental environment alter the molecular landscape of host cells leading to phenotypic changes. These findings reinforce the concept that precise determination of the origins and functional impacts of contamination is imperative for quality research and illustrate the usefulness of the proposed approach to comprehensively characterize contamination landscapes.

Application of Periodontal Ligament-Derived Multipotent Mesenchymal Stromal Cell Sheets for Periodontal Regeneration.

Periodontitis is a chronic inflammatory disorder that causes destruction of the periodontal attachment apparatus including alveolar bone, the periodontal ligament, and cementum. Dental implants have been routinely installed after extraction of periodontitis-affected teeth; however, recent studies have indicated that many dental implants are affected by peri-implantitis, which progresses rapidly because of the failure of the immune system. Therefore, there is a renewed focus on periodontal regeneration aroundnatural teeth. To regenerate periodontal tissue, many researchers and clinicians have attempted to perform periodontal regenerative therapy using materials such as bioresorbable scaffolds, growth factors, and cells. The concept of guided tissue regeneration, by which endogenous periodontal ligament- and alveolar bone-derived cells are preferentially proliferated by barrier membranes, has proved effective, and various kinds of membranes are now commercially available. Clinical studies have shown the significance of barrier membranes for periodontal regeneration; however, the technique is indicated only for relatively small infrabony defects. Cytokine therapies have also been introduced to promote periodontal regeneration, but the indications are also for small size defects. To overcome this limitation, ex vivo expanded multipotent mesenchymal stromal cells (MSCs) have been studied. In particular, periodontal ligament-derived multipotent mesenchymal stromal cells are thought to be a responsible cell source, based on both translational and clinical studies. In this review, responsible cell sources for periodontal regeneration and their clinical applications are summarized. In addition, recent transplantation strategies and perspectives about the cytotherapeutic use of stem cells for periodontal regeneration are discussed.

Allogeneic multipotent mesenchymal stromal cell sheet transplantation promotes healthy healing of wounds caused by zoledronate and dexamethasone in canine mandibular bones.

INTRODUCTION: Many cases of bisphosphonate-related osteonecrosis of the jaw (BRONJ), which is an intractable disease, have been reported. Although a general intravenous injection of multipotent mesenchymal stromal cells (MSCs) may be effective for treating BRONJ, it has some severe problems. Therefore, our aim was to develop a treatment of locally administered MSCs. In this study, we investigated the effect of MSC sheet transplantation in the mandibular bone healing in beagle dogs, which were administered zoledronate and dexamethasone. METHODS: MSCs isolated from subcutaneous fat were seeded onto temperature-responsive culture dishes to produce MSC sheets. Zoledronate and dexamethasone were administered to beagle dogs. Then, the parts of mandibular cortical bones were removed, and MSC sheets were transplanted to cover those bone defects (MSC sheet transplant side) or not (Control side). The specimens were evaluated in micro CT, histology, and immunohistochemistry. RESULTS: Four weeks after surgery, redness and swellings were observed in the mucosal wounds of the control sides of 2 of 3 dogs. In contrast, the mucosal wounds of the MSC sheet transplant sides of all dogs completely healed. Histological images showed some free sequestrums and many bacterial colonies, and Immunohistological analysis showed some cathepsin K-positive multinuclear cells detached from jaw bone surfaces in the control sides. CONCLUSIONS: MSC sheet transplantation promotes healthy healing of wounds caused by zoledronate and dexamethasone in canine mandibular bones. And the injured canine mandibular bones administered zoledronate and dexamethasone showed BRONJ-like findings.

Periodontal regeneration with autologous periodontal ligament-derived cell sheets - A safety and efficacy study in ten patients.

BACKGROUND: Periodontitis results in the destruction of tooth-supporting periodontal tissues and does not have the ability to heal spontaneously. Various approaches have been introduced to regenerate periodontal tissues; however, these approaches have limited efficacy for treating severe defects. Cytotherapies combine stem cell biology and tissue engineering to form a promising approach for overcoming these limitations. In this study, we isolated periodontal ligament (PDL)-derived cells from patients and created cell sheets with "Cell Sheet Engineering Technology", using temperature responsive culture dishes, in which all the cultured cells can be harvested as an intact transplantable cell sheet by reducing the temperature of the culture dish. Subsequently, the safety and efficacy of autologous PDL-derived cell sheets were evaluated in a clinical setting. METHODS: A single-arm and single-institute clinical study was performed to verify the safety and efficacy of autologous PDL-derived cell sheets in patients with periodontitis. Wisdom teeth were extracted from patients diagnosed with chronic periodontitis, ranging in age from 33 to 63 years (mean [±SD], 46 ± 12), and periodontal tissues were scraped for cell sources. Three-layered PDL-derived cell sheets were constructed using temperature-responsive culture dishes and transplanted in an autologous fashion following standard flap surgeries. Bony defects were filled with beta-tricalcium phosphate granules. Clinical variables were evaluated at baseline, 3 months, and 6 months. Cone-beam computed tomography was performed at baseline and 6 months. Additionally, mid-long-term follow-up has been performed with patients' agreements. RESULTS: Our method was found to be safe and no severe adverse events were identified. All the findings, including reduction of periodontal probing depth (mean ± SD, 3.2 ± 1.9 mm), clinical attachment gain (2.5 ± 2.6 mm), and increase of radiographic bone height (2.3 ± 1.8 mm), were improved in all 10 cases at 6 months after the transplantation. These therapeutic effects were sustained during a mean follow-up period of 55 ± 19 months, and there were no serious adverse events. CONCLUSIONS: The results of this study validate the safety and efficacy of autologous PDL-derived cell sheets in severe periodontal defects, and the stability of this efficacy during mid-long-term follow up. This cytotherapeutic approach, based on cell sheet engineering, offers an innovative strategy to treat the recognized unmet need of treating severe periodontal defects.

Thermoresponsive polymer-modified microfibers for cell separations.

Thermoresponsive polymer-modified microfibers were prepared through electrospinning of poly(4-vinylbenzyl chloride) (PVBC) and subsequent surface-initiated atom transfer radical polymerization for grafting poly(N-isopropylacrylamide) (PIPAAm). Electrospinning conditions were optimized to produce large-diameter (20µm) PVBC microfibers. The amount of PIPAAm grafted on the microfibers was controlled via the IPAAm monomer concentration. The microfibers exhibited thermally controlled cell separation by selective adhesion of normal human dermal fibroblasts in a mixed cell suspension that also contained human umbilical vein endothelial cells. In addition, adipose-derived stem cells (ADSCs) exhibited thermally modulated cell adhesion and detachment, while adhesion of other ADSC-related cells was low. Thus, ADSCs could be separated from a mixture of adipose tissue-derived cells simply by changing the temperature. Overall, the PIPAAm-modified microfibers are potentially applicable as temperature-modulated cell separation materials. STATEMENT OF SIGNIFICANCE: Thermoresponsive poly(N-isopropylacrylamide) (PIPAAm) polymer-modified poly(4-vinylbenzyl chloride) (PVBC) microfibers were prepared via electrospinning of PVBC, followed by surface-initiated ATRP. They formed effective thermally-modulated cell separation materials with large surface areas. Cells adhered and extended along the modified microfibers; this was not observed on previously reported PIPAAm-modified flat substrates. The cellular adhesion enabled separation of fibroblast cells, as well as that of adipose-derived mesenchymal stem cells, from mixtures of similar cells. Thus, the temperature-controlled thermoresponsive microfibers would be potentially useful as cell separation materials.

Cytological character of mini pig mesenchymal stromal cells from various tissues and the attempt of cell sheet formation.

INTRODUCTION: Large animal experiments are important for translational research in regenerative medicine. Recently, mini pigs have been used in large animal studies and surgical training. The use of multipotent mesenchymal stromal cell (MSC) sheets for the treatment of many diseases is increasing. The purpose of the present study was to establish optimal methods for generating mini pig MSC sheets from various tissues and to compare the properties of MSCs in these sheets. METHODS: MSCs were isolated from the bone marrow, adipose, periodontal ligament, gingiva, or periosteum of mini pigs. The proliferation, markers, and mRNA expression of these MSCs were examined. Colony-forming and differentiation assays were performed. MSCs were seeded onto temperature-responsive culture dishes to develop MSC sheets. RESULTS: MSCs derived from bone marrow (BMSCs), adipose (ASCs), periodontal ligament (PDLCs), gingiva (GMSCs), and periosteum (PSCs) were positive for MSC-related markers. BMSCs and PSCs showed increased proliferation compared with other MSCs. The osteogenic potential of PDLCs and the adipogenic potential of PSCs were the highest among these MSCs. The expression levels of COL1A1 and COL3A1 in BMSCs and PSCs were significantly higher than those in other MSCs. The expression levels of FGF2, VEGFA, ICAM-1, and TIE-1 in GMSCs were significantly higher than those in other MSCs. PSCs showed the highest levels of TGF-ß1 and ANG-1 expression among all MSC types. We succeeded in developing MSC sheets from BMSCs, ASCs, and PSCs. CONCLUSIONS: We developed methods to generate MSC sheets from various tissues of mini pigs, and these methods are useful to pursue regenerative translational research using mini pigs.

ZBTB16 as a Downstream Target Gene of Osterix Regulates Osteoblastogenesis of Human Multipotent Mesenchymal Stromal Cells.

Human multipotent mesenchymal stromal cells (hMSCs) possess the ability to differentiate into osteoblasts, and they can be utilized as a source for bone regenerative therapy. Osteoinductive pretreatment, which induces the osteoblastic differentiation of hMSCs in vitro, has been widely used for bone tissue engineering prior to cell transplantation. However, the molecular basis of osteoblastic differentiation induced by osteoinductive medium (OIM) is still unknown. Therefore, we used a next-generation sequencer to investigate the changes in gene expression during the osteoblastic differentiation of hMSCs. The hMSCs used in this study possessed both multipotency and self-renewal ability. Whole-transcriptome analysis revealed that the expression of zinc finger and BTB domain containing 16 (ZBTB16) was significantly increased during the osteoblastogenesis of hMSCs. ZBTB16 mRNA and protein expression was enhanced by culturing the hMSCs with OIM. Small interfering RNA (siRNA)-mediated gene silencing of ZBTB16 decreased the activity of alkaline phosphatase (ALP); the expression of osteogenic genes, such as osteocalcin (OCN) and bone sialoprotein (BSP), and the mineralized nodule formation induced by OIM. siRNA-mediated gene silencing of Osterix (Osx), which is known as an essential regulator of osteoblastic differentiation, markedly downregulated the expression of ZBTB16. In addition, chromatin immunoprecipitation (ChIP) assays showed that Osx associated with the ZBTB16 promoter region containing the GC-rich canonical Sp1 sequence, which is the specific Osx binding site. These findings suggest that ZBTB16 acts as a downstream transcriptional regulator of Osx and can be useful as a late marker of osteoblastic differentiation. J. Cell. Biochem. 117: 2423-2434, 2016. © 2016 Wiley Periodicals, Inc.