Micromolar sodium fluoride mediates anti-osteoclastogenesis in Porphyromonas gingivalis-induced alveolar bone loss

Correlations between bone metabolism biomarkers and fluoride exposure in adults and children

Increased exposure to fluoride, which notably affects bone metabolism, is a global concern. However, the correlations and sensitivity of bone metabolism to fluoride remain controversial. In this cross-sectional study, 549 children (aged 7-12 years) and 504 adults (≥ 18 years old) were recruited in the high-fluoride areas of the Henan Province. Urinary fluoride (UF) level was determined using a fluoride electrode. Fasting venous blood serum was collected to measure bone metabolism biomarkers. The selected bone metabolism biomarkers for children included bone alkaline phosphatase (BALP), serum alkaline phosphatase (ALP), osteocalcin (OCN), calcitonin (CT), parathyroid hormone (PTH), phosphorus (P5+), and calcium (Ca2+). For adults, the biomarkers included ALP, CT, PTH, β-CrossLaps (β-CTX), P5+, and Ca2+. The correlations between UF and bone metabolism biomarkers were analyzed using binary logistic regression, a trend test, a generalized additive model, and threshold effect analysis. Regression analysis indicated a significant correlation between serum OCN, PTH, and UF levels in children aged 7-9 years. Serum OCN, PTH, and BALP contents were significantly correlated with UF in boys (P < 0.05). Furthermore, the interaction between age and UF affected serum P5+ and PTH (P < 0.05). The generalized additive model revealed nonlinear dose-response relationships between P5+, BALP, and UF contents in children (P < 0.05). Serum OCN level was linearly correlated with the UF concentration (P < 0.05). Similarly, a significant correlation was observed between β-CTX and UF levels in adults. In addition, significant correlations were observed between UF-age and serum Ca2+, β-CTX, and PTH contents. There was a non-linear correlation between serum Ca2+, P5+, and β- CTX and UF levels (P < 0.05). Overall, serum OCN, BALP, and P5+ levels can serve as sensitive bone metabolism biomarkers in children, while β-CTX, P5+, and Ca2+ can be considered fluoride-sensitive bone metabolism biomarkers in adults.

Concomitant administration of resveratrol and resistance training ameliorates acrylamide-induced spatial learning impairment in rats

Objective

The present study examined effects of resistance training (RT) and resveratrol (RES) alone and together on acrylamide (AC)-induced memory impairment in rats.

Materials and Methods

Animals were divided into 6 groups: (1) Control group which received normal saline intraperitoneally (ip) daily for 8 weeks; (2) Scopolamine (SCO) group which received SCO (1 mg/kg/day, ip) for 8 weeks; (3) AC group which received AC (5 mg/kg/day, ip) for 8 weeks; (4) AC + RT group which received AC (5 mg/kg/day, ip) for 8 weeks and performed RT (5 days a week for 8 weeks); (5) AC + RES group which received AC (5 mg/kg/day, ip) and RES (1 mg/kg/day, ip) for 8 weeks; and (6) AC + RT + RES group which received AC (5 mg/kg/day, ip) and RES (1 mg/kg/day, ip) for 8 weeks and performed RT (5 days a week for 8 weeks). On day 53, animal training began in the Morris Water Maze (MWM) and 24 hr after the last training, the probe test was performed.

Results

RT and RES alone did not significantly affect escape latency or traveled distance increased by AC. However, concomitant RES and RT treatment significantly reduced these parameters compared to the AC group. Co-treatment with RES and RT also significantly increased the time spent in the target quadrant compared to the AC group. Lipid peroxidation was reduced in the AC+RES and AC+RT+RES groups compared to the AC group.

Conclusion

It seems that daily co-treatment with RES and RT for 8 weeks ameliorates the memory-impairing effects of AC.

The Role of Trace Elements and Minerals in Osteoporosis: A Review of Epidemiological and Laboratory Findings

The objective of the present study was to review recent epidemiological and clinical data on the association between selected minerals and trace elements and osteoporosis, as well as to discuss the molecular mechanisms underlying these associations. We have performed a search in the PubMed-Medline and Google Scholar databases using the MeSH terms "osteoporosis", "osteogenesis", "osteoblast", "osteoclast", and "osteocyte" in association with the names of particular trace elements and minerals through 21 March 2023. The data demonstrate that physiological and nutritional levels of trace elements and minerals promote osteogenic differentiation through the up-regulation of BMP-2 and Wnt/β-catenin signaling, as well as other pathways. miRNA and epigenetic effects were also involved in the regulation of the osteogenic effects of trace minerals. The antiresorptive effect of trace elements and minerals was associated with the inhibition of osteoclastogenesis. At the same time, the effect of trace elements and minerals on bone health appeared to be dose-dependent with low doses promoting an osteogenic effect, whereas high doses exerted opposite effects which promoted bone resorption and impaired bone formation. Concomitant with the results of the laboratory studies, several clinical trials and epidemiological studies demonstrated that supplementation with Zn, Mg, F, and Sr may improve bone quality, thus inducing antiosteoporotic effects.

Abalone-Inspired Adhesive and Photo-Responsive Microparticle Delivery Systems for Periodontal Drug Therapy

Antibiotics provide promising strategies for treating periodontitis, while their delivery and controllable release with desired oral retention remain challenging. Here, inspired by the unique suction-cup structures of abalones, a novel adhesive and photo-responsive microparticle (MP) delivery system is developed to treat periodontitis through microfluidic electrospray technology. Such MPs are generated by quickly ionic cross-linking of sodium alginate together with photo-curing of poly(ethylene glycol) diacrylate of the distorted microfluidic droplets during their high-speed dropping into calcium chloride solution. Attributing to their unique concave structures, the abalone-inspired MPs exhibit desired underwater adhesion ability and stability under running water. In addition, due to the loading of antibiotics minocycline hydrochloride and near-infrared (NIR)-responsive black phosphorus during their fabrication, the resultant MPs can not only eradicate bacteria directly, but also realize a controllable and effective drug release upon NIR irradiation. Based on these features, it is demonstrated from in vivo periodontitis that the abalone-inspired MPs are firmly adhesive and can controlled-release drugs on the tooth, and thus have outstanding antibacterial efficacy against Porphyromonas gingivalis. These results indicate the particular values of the abalone-inspired MPs for oral-related disease treatment.

Allicin Improves Intestinal Epithelial Barrier Function and Prevents LPS-Induced Barrier Damages of Intestinal Epithelial Cell Monolayers

Gut barrier disruption is the initial pathogenesis of various diseases. We previously reported that dietary allicin improves tight junction proteins in the endoplasmic reticulum stressed jejunum. However, whether the allicin benefits the gut barrier within mycotoxin or endotoxin exposure is unknown. In the present study, IPEC-J2 cell monolayers within or without deoxynivalenol (DON) or lipopolysaccharide (LPS) challenges were employed to investigate the effects of allicin on intestinal barrier function and explore the potential mechanisms. Results clarified that allicin at 2 μg/mL increased the viability, whereas the allicin higher than 10 μg/mL lowered the viability of IPEC-J2 cells via inhibiting cell proliferation. Besides, allicin increased trans-epithelial electric resistance (TEER), decreased paracellular permeability, and enhanced ZO-1 integrity of the IPEC-J2 cell monolayers. Finally, allicin supplementation prevented the LPS-induced barrier damages via activating Nrf2/HO-1 pathway-dependent antioxidant system. In conclusion, the present study strongly confirmed allicin as an effective nutrient to improve intestinal barrier function and prevent bacterial endotoxin-induced barrier damages.

Biphasic Functions of Sodium Fluoride (NaF) in Soft and in Hard Periodontal Tissues

Sodium fluoride (NaF) is widely used in clinical dentistry. However, the administration of high or low concentrations of NaF has various functions in different tissues. Understanding the mechanisms of the different effects of NaF will help to optimize its use in clinical applications. Studies of NaF and epithelial cells, osteoblasts, osteoclasts, and periodontal cells have suggested the significant roles of fluoride treatment. In this review, we summarize recent studies on the biphasic functions of NaF that are related to both soft and hard periodontal tissues, multiple diseases, and clinical dentistry.

Central Regulatory Role of Cytokines in Periodontitis and Targeting Options

BACKGROUND

Periodontitis is an immune-inflammatory disease that leads to the progressive destruction of bone and connective tissue in the periodontal area. The cytokine network plays a primary role in tissue homeostasis, the recruitment of immune cells to control the pathogenic impact and the regulation of osteoclastic function, thus modulating the intensity and duration of the immune response. This review provides an update on the main cytokines implicated in the pathogenesis and progression of periodontitis and their targeting potential in order to enrich current treatment options.

METHODS

A structured search of bibliographic databases (PubMed, MEDLINE, Scopus) was performed for peer-reviewed cytokine studies focused on periodontitis the last ten years. A qualitative content analysis was performed in screened papers and a critical discussion of main findings is provided.

RESULTS

An altered cytokine profile has been detected in periodontitis patients and the interplay of pro-inflammatory and/or anti-inflammatory cytokines has been associated with disease pathogenesis. Among the most prominent pro-inflammatory cytokines, TNF-α, IL-1β, IL-17, IL-6 and the chemokines CXCL-6, CXCL-8 are overexpressed in periodontitis patients and correlate with disease progression. On the other hand, the anti-inflammatory IL-4 and IL- 11 levels are reduced while IL-12 and IFN-γ expression play a dual role in periodontal disease. Current periodontitis treatment strategies include selective antibiotics, antimicrobial photodynamic therapy and probiotics, which can modulate the cytokine network and when applied in combination with specific anti-cytokine agents can exert additional beneficial effects.

CONCLUSION

It is evident that cytokines play a central regulatory role in the inflammatory process and immune cell response that underlies bone destruction in periodontitis. Specific cytokine targeting should be considered as a complementary therapeutic scheme to current periodontal management.

Matrix Metalloproteinase 9 is Regulated by LOX-1 and erk1/2 Pathway in Dental Peri-Implantitis

BACKGROUND AND OBJECTIVE

Dental peri-implantitis, which can be caused by several different microbial factors, is characterized by inflammatory lesions of the surrounding hard and soft tissues of an oral implant. Matrix Metalloproteinase 9 (MMP9) is thought to be involved in the pathogenesis of peri-implantitis. However, the regulatory mechanism of MMP9 in peri-implantitis has not been fully elucidated. In this study, we tried to evaluate the regulatory mechanism of MMP9 in peri-implantitis.

METHODS

We collected Peri-Implant Crevicular Fluid (PICF) from ten healthy implants and ten periimplantitis patients and compared their expression level of MMP9. We also cultured macrophages from the peripheral blood of healthy volunteers infected by Porphyromonas gingivalis to reveal the regulatory mechanism of MMP9 in peri-implantitis. Western blot, immunofluorescence staining and quantitative Polymerase Chain Reaction (RT-PCR) were used to better characterize the mechanism of MMP9.

RESULTS

The expression of MMP9 was up-regulated in peri-implantitis patient PICF and P. gingivalis infected human macrophages. LOX-1, not dectin-1, was found to mediate MMP9 expression in human macrophages with P. gingivalis infection. Expression of Erk1/2 was responsible for infection-induced MMP9 expression. Finally, use of a broad-spectrum metalloproteinase inhibitor impaired LOX-1 expression in infected macrophages.

CONCLUSION

Our results demonstrate that MMP9 is involved in dental peri-implantitis and is regulated by LOX-1 and Erk1/2. This LOX-1/MMP9 signaling pathway may represent a potential drug target for peri-implantitis.

Interleukin-1β is a potential therapeutic target for periodontitis: a narrative review

Interleukin(IL)-1β, a pro-inflammatory cytokine, was elevated and participates in periodontitis. Not only the link between IL-1β and periodontitis was proved by clinical evidence, but also the increased IL-1β triggers a series of inflammatory reactions and promotes bone resorption. Currently, IL-1β blockage has been therapeutic strategies for autoimmune and autoinflammatory diseases such as rheumatoid arthritis, cryopyrin-associated periodic syndromes, gout and type II diabetes mellitus. It is speculated that IL-1β be a potential therapeutic target for periodontitis. The review focuses on the production, mechanism, present treatments and future potential strategies for IL-1β in periodontitis.

Different Effects of Fluoride Exposure on the Three Major Bone Cell Types

Fluoride accumulates and is toxic to bones. Clinical bone lesions occur in a phased manner, being less severe early in the natural course of skeletal fluorosis. Previous research rarely focused on osteocyte, osteoclast, and osteoblast at the same time, although these three types of cells are involved in the process of fluorosis. In this study, commitment of bone cells was performed according to their respective characteristics. Osteocyte-like cells were verified by protein expression of sclerostin (SOST) in IDG-SW3 cell culture with mineral medium. Positive tartrate-resistant acid phosphatase (TRACP) staining, characteristic of osteoclasts, is observed in RAW264.7 cells after administration of RANKL. We successfully purified a high percentage (94%) of bone mesenchymal stem cells (BMSCs) co-expressing CD34 and CD44. Parallel studies were performed to observe cell viability and apoptosis rates in osteocyte, osteoclast, and osteoblast like cells by using MTT and Annexin V FITC assays. Our results demonstrated that osteocytes have a strong tolerance to high fluoride concentrations, while osteoclasts are more sensitive to changes of fluoride dose. The range of anabolic action of fluoride concentration on osteoblast was narrow. Notably, fluoride exposure aggravated apoptosis of osteocyte and osteoclast induced by administration of PTH and TGF-β, respectively. In short, three types of bone cells display disparate responses to fluoride exposure and to PTH- and TGF-β-induced apoptosis.

Fluorine-contained hydroxyapatite suppresses bone resorption through inhibiting osteoclasts differentiation and function in vitro and in vivo

Objectives

Fluorine, an organic trace element, has been shown to unfavourably effect osteoclasts function at a low dose. Use of hydroxyapatite (HA) has been effective in exploring its roles in promoting bone repair. In this study, we used HA modified with fluorine to investigate whether it could influence osteoclastic activity in vitro and ovariectomy‐induced osteoclasts hyperfunction in vivo.

Materials and methods

Fluorohydroxyapatite (FHA) was obtained and characterized by scanning electron microscope (SEM). Osteoclasts proliferation and apoptosis treated with FHA were assessed by MTT and TUNEL assay. SEM, F‐actin, TRAP activity and bone resorption experiment were performed to determine the influence of FHA on osteoclasts differentiation and function. Moreover, HA and FHA were implanted into ovariectomized osteoporotic and sham surgery rats. Histology and Micro‐CT were examined for further verification.

Results

Fluorine released from FHA slowly and sustainably. FHA hampered osteoclasts proliferation, promoted osteoclasts apoptosis, suppressed osteoclasts differentiation and function. Experiments in vivo validated that FHA participation brought about an inhibitory effect on osteoclasts hyperfunction and less bone absorption.

Conclusion

The results indicated that FHA served as an efficient regulator to attenuate osteoclasts formation and function and was proposed as a candidature for bone tissue engineering applications.

Fluorination Enhances the Osteogenic Capacity of Porcine Hydroxyapatite

In a previous study, we successfully prepared fluorinated porcine hydroxyapatite (FPHA) by immersing porcine hydroxyapatite (PHA) in an aqueous solution of 0.25 M sodium fluoride (NaF) under thermal treatment, and the resulting FPHA showed better physicochemical and biological properties than PHA. The purpose of this study was to further investigate how fluorine incorporation influenced the biocompatibility and osteogenic capacity of PHA. The concentrations of Ca, P, F, and Mg ions in PHA and FPHA extracts were detected by inductively coupled plasma optical emission spectrometry. Rat bone marrow stromal cells (rBMSCs) were treated with PHA and FPHA extracts, and the effects of these extracts on cell proliferation and osteoblastic differentiation were evaluated via Cell Counting Kit-8 assay, alkaline phosphatase assay, and real time-quantitative polymerase chain reaction. For the in vivo assessment, PHA and FPHA were implanted into subcutaneous pockets (n = 6) and rat calvarial defects (diameter = 5 mm, n = 14) for 12 weeks to determine their biocompatibility and osteogenic capacity by using micro-computed tomography (CT) and histological analysis. FPHA extracts, which release higher concentrations of F and Mg ions, better promoted the osteoblastic differentiation of rBMSCs in vitro. The result of biocompatibility evaluation confirmed that the host response and chronic inflammation cells infiltration degree around PHA and FPHA granules were similar. Micro-CT and histological analysis showed newer mineralized bone formation in rats with FPHA-treated defects than in rats with PHA-treated defects. The results of in vitro and in vivo tests consistently indicate that fluorine incorporation effectively enhanced the osteogenic capacity of PHA.

Effects of Fluoride on Bone in an Animal Model of Vitamin D Deficiency

We investigated the combined effect of fluoride exposure and Vitamin D deficiency in causing bone damage as a precursor to development of Fluorotoxic Metabolic Bone Disease. Thirty-six male Sprague-Dawley rats were divided into 6 groups of six; 3 groups received a Vitamin D deficient diet whereas the other 3 received a Vitamin D adequate diet. Serum total 25-hydroxyvitamin D (25OHD), calcium, phosphorus, creatinine, Alkaline phosphatase (ALP), albumin, Parathyroid hormone (PTH), Osteocalcin and C terminal telopeptide (CTx) were measured following exposure to varying levels of fluoride in drinking water (< 1.0, 15 and 50 ppm). Full body Dual-energy X-ray Absorptiometry (DXA) scans were used to examine changes in bone morphology pre and post exposure to fluoride. Renal tubular function was assessed using serum creatinine and urine Cystatin C. Histopathological examination of sections of bone and kidney tissues were also performed. Prior to fluoride exposure, DXA scans revealed a significant decrease in Bone Mineral Density (BMD) and Bone Mineral content (BMC) (p < 0.05) but a significant increase in fat mass (p < 0.05) and fat percentage (p < 0.01) among Vitamin D deficient rats, with no significant change in biochemical parameters. Following exposure to fluoride, BMD was significantly increased (p < 0.05) in both groups with a corresponding increase in serum ALP, bone fluoride content, Osteocalcin, CTx and urine fluoride with increasing levels of fluoride exposure. Serum creatinine calcium and phosphate and urinary cystatin C levels showed no significant changes. Light microscopy examination revealed mild thickening and increased osteoid in 80% of the Vitamin D deficient rats exposed to high levels of fluoride but renal tubular changes were found only in one experimental and one control animal. Fluoride deposited in rat bone affects both osteoblastic and osteoclastic activity. Also, these effects are accentuated in the presence of Vitamin D deficiency.

The role of TGFβ receptor 1-smad3 signaling in regulating the osteoclastic mode affected by fluoride

Studies that have focused on the role TGFβ signaling plays in osteoclast activity are gradually increasing; however, literature is rare in terms of fluorosis. The aim of this study is to observe the role the TβR1/Smad3 pathway plays in fluoride regulating cellsosteoclast-like cells that are under the treatment of TGFβ receptor 1 kinase. The RANKL-mediated osteoclast-like cells from RAW264.7 cells were used as osteoclast precursor model. The profile of miRNA expression in fluoride-treated osteoclast-like cells exhibited 303 upregulated miRNAs, 61 downregulated miRNAs, and further drew 37 signaling pathway maps by KEGG and Biocarta pathway enrichment analysis. TGFβ and its downstream effectors were included among them. Osteoclast viability, formation and function were detected via MTT method, bone resorption pit and tartrate-resistant acid phosphatase (TRACP) staining, respectively. Results demonstrated that different doses of fluoride exhibited a biphasic effect on osteoclast cell viability, differentiation, formation and function. It indicated that a low dose of fluoride treatment stimulated them, but high dose inhibited them. SB431542 acted as TβR1 kinase inhibitor and blocked viability, formation and function of osteoclast-like cells regulated by fluoride. The expression of the osteoclast marker, RANK, and TβR1/Smad3 at gene and protein level was analyzed under fluoride with and without SB431542 treatment. Fluoride treatment indicated little effect on the RANK protein expression; however it significantly influenced TRACP expression in osteoclast-like cells. The stimulation of fluoride on the expression of Smad3 gene and phosphorylated Smad3 protein exhibited dose-dependent manner. SB431542 significantly impeded phosphorylation of Smad3 protein and TRACP expression in osteoclast-like cells that were exposed to fluoride. Our work demonstrated that TGFβ signaling played a key role in fluoride regulating osteoclast differentiation, formation and function. It elucidated that TβR1/Smad3 pathway participated in the mechanism of biphasic modulation of osteoclast mode regulated by fluoride.

The epigenetic regulation of CXCL14 plays a role in the pathobiology of oral cancers

Background: Chemokines selectively attract and activate leukocytes and play roles in a variety of homeostatic and disease processes. Explore the biological properties of CXCL14 seems complicated due to unknown functional characteristics of CXCL14 in cancer. Methods: To study the multistep process of oral cancer development, we analyzed oral samples spanning normalcy, dysplasia and cancer from multiple perspectives, revealing a cascade of progressive changes. Results: CXCL14 protein was expressed in the cytoplasm adjacent to tumors. T classification (P<0.001), clinical stage (P=0.0013) and nodal metastasis (P=0.0035) were significantly associated with CXCL14 in relationships between CXCL14 expression levels and tumor and patient characteristics. Compared with non-tumor tissue, expression of the epidermal growth factor receptor (EGFR) gene was increased in dysplasia and was further sustained in cancer. Our data show an inverse relationship between CXCL14 and EGFR expression levels in tumor cells indicating that CXCL14 expression is beneficial for tumor suppression. To explore epigenetic regulation and the impact of CXCL14 on oral cancer, analysis of CpG islands methylation in the CXCL14 promoter region indicated that the abnormal hypermethylation of that promoter region in tumor cells and tissues is one of the mechanisms causing the reduced expression. Restoration of CXCL14 expression was induced by treatment with 5-aza-2'-deoxycytidine. Using in vivo mouse models, we demonstrate that the restoration of CXCL14 expression in irradiation-induced oral carcinoma cells induces the expression of Late Cornified Envelope (LCE) genes. Conclusions: Our data suggest that LCE genes are a novel target of CXCL14 and are likely to have a tumor suppressor function through the modulation of CXCL14 expression. In conclusion, CXCL14 might play a pivotal role in the pathobiology of oral cancer, probably by regulating DNA methylation and leukocyte migration. The level of CXCL14 expression may be a valuable adjuvant parameter to predict the prognosis of patients with oral carcinoma and may be a potential therapeutic target.

Micromolar Levels of Sodium Fluoride Promote Osteoblast Differentiation Through Runx2 Signaling

Bone remodeling is a vital physiological process of healthy bone tissue in humans. Imbalances in this vital process lead to pathological conditions, including periodontal diseases. In this study, we characterized the effects of micromolar levels of NaF on the proliferation and osteogenic differentiation of MC3T3-E1 osteoblastic cells. NaF significantly enhanced the proliferation, alkaline phosphatase (ALP) activity, and mineralization of MC3T3-E1 cells. Quantitative real-time PCR analysis revealed that the expression of mRNAs encoding runt-related transcription factor 2 (Runx2), Osterix, Osteopontin and Osteocalcin was up-regulated in NaF-treated MC3T3-E1 cells compared with untreated controls. Western blot analysis demonstrated that Runx2 and Osterix were inhibited by Runx2 siRNA but were re-activated by treatment with NaF. Furthermore, in vivo evidence indicated that NaF protects against Porphyromonas gingivalis-induced periodontal inflammation and alveolar bone loss in a P. gingivalis-challenged experimental periodontitis animal model. These data suggest that NaF promotes the osteoblastic differentiation of MC3T3-E1 cells through the Runx2/Osterix pathway and may be effective for the treatment of bone-related disorders.

Effects of fluoride on insulin signaling and bone metabolism in ovariectomized rats

Fluoride is an essential trace element for the maintenance of bone health owing to its capacity to stimulate proliferation and osteoblastic activity that can lead to increased bone formation. However, excessive sodium fluoride (NaF) intake can impair carbohydrate metabolism thereby promoting hyperglycemia, insulin resistance, and changes in insulin signaling. Thus, this study aimed to evaluate the effect of chronic treatment with NaF in bone metabolism, insulin signaling, and plasma concentrations of glucose, insulin, tumor necrosis factor-α (TNF-α), osteocalcin (OCN), and fluoride in ovariectomized rats. Thirty-two ovariectomized Wistar rats were randomly distributed into two groups: Control (OVX-C) and those undergoing treatment with NaF (50mg F/L) in drinking water for 42days (OVX-F). Glucose and insulin levels were assessed, followed by homeostasis model assessment of insulin resistance (HOMA-IR). Akt serine phosphorylation was evaluated by western blotting. Plasma concentrations of TNF-α and OCN were evaluated by ELISA. The left and right tibia was collected for immunohistochemical and histomorphometric analysis, respectively. Chronic treatment with NaF promoted insulin resistance, decreased insulin signal, increased plasma concentration of insulin, fluoride, OCN and TNF-α, decreased trabecular bone area of the tibia, and caused changes in bone metabolism markers in ovariectomized rats. These results suggest the need for caution in the use of NaF for the treatment of osteoporosis, especially in postmenopausal woman.

Environmental Factors Impacting Bone-Relevant Chemokines

Chemokines play an important role in normal bone physiology and the pathophysiology of many bone diseases. The recent increased focus on the individual roles of this class of proteins in the context of bone has shown that members of the two major chemokine subfamilies-CC and CXC-support or promote the formation of new bone and the remodeling of existing bone in response to a myriad of stimuli. These chemotactic molecules are crucial in orchestrating appropriate cellular homing, osteoblastogenesis, and osteoclastogenesis during normal bone repair. Bone healing is a complex cascade of carefully regulated processes, including inflammation, progenitor cell recruitment, differentiation, and remodeling. The extensive role of chemokines in these processes and the known links between environmental contaminants and chemokine expression/activity leaves ample opportunity for disruption of bone healing by environmental factors. However, despite increased clinical awareness, the potential impact of many of these environmental factors on bone-related chemokines is still ill defined. A great deal of focus has been placed on environmental exposure to various endocrine disruptors (bisphenol A, phthalate esters, etc.), volatile organic compounds, dioxins, and heavy metals, though mainly in other tissues. Awareness of the impact of other less well-studied bone toxicants, such as fluoride, mold and fungal toxins, asbestos, and chlorine, is also reviewed. In many cases, the literature on these toxins in osteogenic models is lacking. However, research focused on their effects in other tissues and cell lines provides clues for where future resources could be best utilized. This review aims to serve as a current and exhaustive resource detailing the known links between several classes of high-interest environmental pollutants and their interaction with the chemokines relevant to bone healing.

Modulation of stromal cell-derived factor 1 alpha (SDF-1α) and its receptor CXCR4 in Porphyromonas gingivalis-induced periodontal inflammation

Background

The production of chemokines by tissue resident cells during inflammation is considered one of the main mechanisms involved in the formation of inflammatory infiltrates. Fibroblasts are the main resident cell type in gingival and periodontal ligament tissues, and their ability to produce chemokine stromal cell-derived factor 1 alpha (SDF-1α) and its receptor CXCR4 under stimulation by gram negative bacteria, Porphyromonas gingivalis, commonly found in periodontal infections was investigated.

Methods

Western blots were used to assess SDF-1α and CXCR4 protein expression levels in human gingival fibroblast cells (HGF-1) induced by Lipopolysaccharide (LPS) from P. gingivalis in the presence or absence of LY294002, a highly selective inhibitor of PI-3K/Akt. RT-PCR and quantitative Real-time PCR was performed using gingival mRNAs from periodontitis patients. Immunohistochemistry was performed to analyze the expression and subcellular localization of SDF-1α and CXCR4, together with NF-kβ phosphorylation, in specimens from patients with periodontitis and in an experimental rat periodontitis model.

Results

We found that P. gingivalis LPS up-regulated SDF-1α and CXCR4 protein levels and elevated phosphorylation of the SDF-1α-responsive NF-kβ and Akt at 24 h in HGF-1 cells. SDF-1α and CXCR4 mRNA and protein expression levels were high in all patients with periodontitis. In the P. gingivalis-induced rat experimental periodontitis model, SDF-1α and CXCR4 immunoreactivity was higher in gingival and periodontal ligament tissues compared to the control.

Conclusion

Our data showed that PI-3K/Akt is an upstream participant in the P. gingivalis LPS-mediated induction of SDF-1α. Taken together, these results suggest that the chemokine SDF-1α and its receptor CXCR4 contribute to P. gingivalis-induced periodontal inflammation.

Comparison of Experimental Diabetic Periodontitis Induced by Porphyromonas gingivalis in Mice

Periodontitis is one of the severe complications in diabetic patients and gingival epithelium plays an initial role on the onset and progression of this disease. However the potential mechanism is yet sufficiently understood. Meanwhile, the research on the correlational experimental animal models was also insufficient. Here, we established periodontitis with type 2 diabetes in db/db and Tallyho/JngJ (TH) mice and periodontitis with type 1 diabetes in streptozotocin induced diabetes C57BL/6J (STZ-C57) mice by oral infection of periodontal pathogen Porphyromonas gingivalis W50. We demonstrated that periodontal infected mice with high blood glucose levels showed dramatically more alveolar bone loss than their counterparts, in which infected db/db mice exhibited the most bone defects. No contrary impact could be observed between this periodontal infection and onset and severity of diabetes. The expressions of PTPN2 were inhibited whereas the expression of JAK1, STAT1, and STAT3 increased dramatically in gingival epithelia and the serum TNF-α also significantly increased in the mice with diabetic periodontitis. Our results indicated that the variations of inflammation-related protein expressions in gingival epithelia might lead to the phenotype differences in the mice with diabetic periodontitis.