Powder diet exacerbates oropharyngeal candidiasis in a mouse model.

This study reports on the influence of a powder diet in a mouse model of oropharyngeal candidiasis (OPC), a significant health concern caused primarily by Candida albicans. Despite identical nutritional composition, we found that a powdered diet significantly increased Candida burdens and oral lesions, and aggravated weight loss compared to a standard pelleted diet. High fungal burdens and severe oral lesions were accomplished within 48 hours after infection with only one dose of cortisone. Moreover, mice on a powder diet recovered a week after infection. Using a powder diet, we thus modified the cortisone OPC murine model in a way that simplifies the infection process, enhances reproducibility, and facilitates studies investigating both pathogenesis and recovery processes. Our findings also underscore the pivotal role of the physical form of the diet in the progression and severity of oral Candida infection in this model. Future research should investigate this relationship further to broaden our understanding of the underlying mechanisms, potentially leading to novel prevention strategies and improved disease management.IMPORTANCEOropharyngeal candidiasis (OPC) is a multifactorial disease and a significant health concern. We found that the physical form of the diet plays a critical role in the severity and progression of OPC. We developed a modified cortisone OPC murine model that facilitates studies investigating pathogenesis and recovery processes.

Newly Developed Low Dose 180-degree CBCT Protocol Reduces Radiation Dose Without Compromising Diagnostic Value.

PURPOSE: To compare the standard 360-degree CBCT acquisition protocol to the low dose 180-degree CBCT protocol for implant planning. MATERIALS AND METHODS: Two groups of patients, each consisting of 35 patients, were included in the study. The first group was imaged with the conventional 360-degree CBCT protocol, and the second group was imaged with the low dose 180-degree CBCT protocol. The primary outcome of this study was the number of scans that needed to be repeated due to poor image quality. In addition, six secondary parameters were evaluated quantitatively and qualitatively. RESULTS: The results showed that there was no need to repeat any of the CBCT scans that were obtained in either group, which showed that 360-degree and 180-degree protocols had comparable image quality. As for the secondary parameters, the results showed that the evaluators were able to evaluate the six chosen parameters in a comparable manner. CONCLUSIONS: The 180-degree low dose CBCT scan is a viable option for dental implant treatment planning in the posterior mandible as it provides comparable and adequate information regarding accuracy of measurements, identification of critical structures, evaluation of bone quality, and any pathology.

A prebiotic diet modulates the oral microbiome composition and results in the attenuation of oropharyngeal candidiasis in mice.

Oral bacteria can influence the ability of Candida albicans to cause oropharyngeal candidiasis (OPC). We recently reported that a Lactobacillus johnsonii-enriched oral microbiota reduced C. albicans virulence in an immunosuppressed OPC mouse model. As a follow-up, in this work, we aimed to enrich the resident oral Lactobacillus communities with a prebiotic diet to further assess their effect on the severity of OPC. We tested the effect of a prebiotic xylo-oligosaccharides (XOS)-enriched diet in the oral global bacterial composition and severity of OPC. We assessed changes in the oral microbiome composition via 16S-rRNA gene high-throughput sequencing, validated by qPCR. The impact of the prebiotic diet on Candida infection was assessed by quantifying changes in oral fungal and bacterial biomass and scoring tongue lesions. Contrary to expectations, oral Lactobacillus communities were not enriched by the XOS-supplemented diet. Yet, XOS modulated the oral microbiome composition, increasing Bifidobacterium abundance and reducing enterococci and staphylococci. In the OPC model, the XOS diet attenuated Candida virulence and bacterial dysbiosis, increasing lactobacilli and reducing enterococci on the oral mucosa. We conclude that XOS attenuates Candida virulence by promoting a bacterial microbiome structure more resilient to Candida infection. IMPORTANCE This is the first study on the effects of a prebiotic diet on the oral mucosal bacterial microbiome and an oropharyngeal candidiasis (OPC) mouse model. We found that xylo-oligosaccharides change the oral bacterial community composition and attenuate OPC. Our results contribute to the understanding of the impact of the oral bacterial communities on Candida virulence.

Newly Developed Low Dose 180-degree CBCT Protocol Reduces Radiation Dose Without Compromising Diagnostic Value.

PURPOSE: To compare the standard 360-degree CBCT acquisition protocol to the low dose 180-degree CBCT protocol for implant planning. MATERIALS AND METHODS: Two groups of patients, each consisting of 35 patients, were included in the study. The first group was imaged with the conventional 360-degree CBCT protocol, and the second group was imaged with the low dose 180-degree CBCT protocol. The primary outcome of this study was the number of scans that needed to be repeated due to poor image quality. In addition, six secondary parameters were evaluated quantitatively and qualitatively. RESULTS: The results showed that there was no need to repeat any of the CBCT scans that were obtained in either group, which showed that 360-degree and 180-degree protocols had comparable image quality. As for the secondary parameters, the results showed that the evaluators were able to evaluate the six chosen parameters in a comparable manner. CONCLUSION: The 180-degree low dose CBCT scan is a viable option for dental implant treatment planning in the posterior mandible as it provides comparable and adequate information regarding accuracy of measurements, identification of critical structures, evaluation of bone quality, and any pathology.

Insights From the Lactobacillus johnsonii Genome Suggest the Production of Metabolites With Antibiofilm Activity Against the Pathobiont Candida albicans.

Lactobacillus johnsonii is a probiotic bacterial species with broad antimicrobial properties; however, its antimicrobial activities against the pathobiont Candida albicans are underexplored. The aim of this study was to study the interactions of L. johnsonii with C. albicans and explore mechanisms of bacterial anti-fungal activities based on bacterial genomic characterization coupled with experimental data. We isolated an L. johnsonii strain (MT4) from the oral cavity of mice and characterized its effect on C. albicans growth in the planktonic and biofilm states. We also identified key genetic and phenotypic traits that may be associated with a growth inhibitory activity exhibited against C. albicans. We found that L. johnsonii MT4 displays pH-dependent and pH-independent antagonistic interactions against C. albicans, resulting in inhibition of C. albicans planktonic growth and biofilm formation. This antagonism is influenced by nutrient availability and the production of soluble metabolites with anticandidal activity.

Biomarkers of orthodontic tooth movement with fixed appliances and vibration appliance therapy: a pilot study.

INTRODUCTION: The aim of this study was to investigate the effect of supplemental vibratory force on biomarkers of bone remodelling during orthodontic tooth movement, the rate of mandibular anterior alignment (RMAA), and compliance with a vibration device. DESIGN, SETTINGS, AND PARTICIPANTS: Forty patients between the ages 15-35 undergoing fixed appliance treatment that presented to a university orthodontic clinic were randomly allocated to supplemental use of an intraoral vibrational device (n = 20, AcceleDent®) or fixed appliance only (n = 20). Salivary multiplex assay was completed to analyse the concentration of selected biomarkers of bone remodelling before treatment (T0) and at three following time points (T1, T2, T3), 4-6 weeks apart. Irregularity of the mandibular anterior teeth and compliance was assessed at the same trial time points. Data were analysed blindly on an intention-to-treat basis with descriptive statistics, Mann-Whitney U-test, Wilcoxon signed-rank test, and linear mixed effects regression modelling. RESULTS: No difference in the changes in salivary biomarkers of bone remodelling and RMAA between groups at any time point over the trial duration was observed. No correlation was found between changes in irregularity and biomarker level from baseline to another time point. Lastly, there was no association between RMAA and compliance with the AcceleDent® device. CONCLUSIONS: Supplemental vibratory force during orthodontic treatment with fixed appliances does not affect biomarkers of bone remodelling or the RMAA. LIMITATIONS: The main limitation of the study was the small sample size and the large variability in the salivary biomarkers. HARMS: No harms were observed during the duration of the trial. PROTOCOL: The protocol was not published prior to trial commencement. REGISTRATION: The study was registered in Clinical Trials.gov (NCT02119455) first posted on April 2014.

Chemotherapy-induced oral mucositis is associated with detrimental bacterial dysbiosis.

BACKGROUND: Gastrointestinal mucosal injury (mucositis), commonly affecting the oral cavity, is a clinically significant yet incompletely understood complication of cancer chemotherapy. Although antineoplastic cytotoxicity constitutes the primary injury trigger, the interaction of oral microbial commensals with mucosal tissues could modify the response. It is not clear, however, whether chemotherapy and its associated treatments affect oral microbial communities disrupting the homeostatic balance between resident microorganisms and the adjacent mucosa and if such alterations are associated with mucositis. To gain knowledge on the pathophysiology of oral mucositis, 49 subjects receiving 5-fluorouracil (5-FU) or doxorubicin-based chemotherapy were evaluated longitudinally during one cycle, assessing clinical outcomes, bacterial and fungal oral microbiome changes, and epithelial transcriptome responses. As a control for microbiome stability, 30 non-cancer subjects were longitudinally assessed. Through complementary in vitro assays, we also evaluated the antibacterial potential of 5-FU on oral microorganisms and the interaction of commensals with oral epithelial tissues. RESULTS: Oral mucositis severity was associated with 5-FU, increased salivary flow, and higher oral granulocyte counts. The oral bacteriome was disrupted during chemotherapy and while antibiotic and acid inhibitor intake contributed to these changes, bacteriome disruptions were also correlated with antineoplastics and independently and strongly associated with oral mucositis severity. Mucositis-associated bacteriome shifts included depletion of common health-associated commensals from the genera Streptococcus, Actinomyces, Gemella, Granulicatella, and Veillonella and enrichment of Gram-negative bacteria such as Fusobacterium nucleatum and Prevotella oris. Shifts could not be explained by a direct antibacterial effect of 5-FU, but rather resembled the inflammation-associated dysbiotic shifts seen in other oral conditions. Epithelial transcriptional responses during chemotherapy included upregulation of genes involved in innate immunity and apoptosis. Using a multilayer epithelial construct, we show mucositis-associated dysbiotic shifts may contribute to aggravate mucosal damage since the mucositis-depleted Streptococcus salivarius was tolerated as a commensal, while the mucositis-enriched F. nucleatum displayed pro-inflammatory and pro-apoptotic capacity. CONCLUSIONS: Altogether, our work reveals that chemotherapy-induced oral mucositis is associated with bacterial dysbiosis and demonstrates the potential for dysbiotic shifts to aggravate antineoplastic-induced epithelial injury. These findings suggest that control of oral bacterial dysbiosis could represent a novel preventive approach to ameliorate oral mucositis.

Candida albicans induces mucosal bacterial dysbiosis that promotes invasive infection.

Infectious complications are a common cause of morbidity and mortality in cancer patients undergoing chemotherapy due to increased risk of oral and gastrointestinal candidiasis, candidemia and septicemia. Interactions between C. albicans and endogenous mucosal bacteria are important in understanding the mechanisms of invasive infection. We published a mouse intravenous chemotherapy model that recapitulates oral and intestinal mucositis, and myelosuppression in patients receiving 5-fluorouracil. We used this model to study the influence of C. albicans on the mucosal bacterial microbiome and compared global community changes in the oral and intestinal mucosa of the same mice. We validated 16S rRNA gene sequencing data by qPCR, in situ hybridization and culture approaches. Mice receiving both 5Fu and C. albicans had an endogenous bacterial overgrowth on the oral but not the small intestinal mucosa. C. albicans infection was associated with loss of mucosal bacterial diversity in both sites with indigenous Stenotrophomonas, Alphaproteobacteria and Enterococcus species dominating the small intestinal, and Enterococcus species dominating the oral mucosa. Both immunosuppression and Candida infection contributed to changes in the oral microbiota. Enterococci isolated from mice with oropharyngeal candidiasis were implicated in degrading the epithelial junction protein E-cadherin and increasing the permeability of the oral epithelial barrier in vitro. Importantly, depletion of these organisms with antibiotics in vivo attenuated oral mucosal E-cadherin degradation and C. albicans invasion without affecting fungal burdens, indicating that bacterial community changes represent overt dysbiosis. Our studies demonstrate a complex interaction between C. albicans, the resident mucosal bacterial microbiota and the host environment in pathogenesis. We shed significant new light on the role of C. albicans in shaping resident bacterial communities and driving mucosal dysbiosis.

Model of Chemotherapy-associated Mucositis and Oral Opportunistic Infections.

Oral mucositis is a common complication of cancer chemotherapy treatment. Because of the lack of relevant oral mucositis experimental models, it is not clear how chemotherapeutic agents injure the oral mucosa and if commensal microorganisms accelerate tissue damage. We developed an organotypic oral mucosa model that mimics cellular responses commonly associated with cytotoxic chemotherapy. The organotypic model consists of multilayer oral epithelial cells growing over a collagen type I matrix, with embedded fibroblasts. Treatment of organotypic constructs with the chemotherapeutic agent, 5-fluorouracil (5-FU), leads to major histopathologic changes resembling mucositis, such as DNA synthesis inhibition, increased apoptosis and cytoplasmic vacuolation. Candida albicans formed mucosal biofilms on these tissues and augmented the inflammatory responses to 5-FU. This model can be used in further mechanistic studies of oral mucositis and associated opportunistic infections.

S. oralis activates the Efg1 filamentation pathway in C. albicans to promote cross-kingdom interactions and mucosal biofilms.

Candida albicans and Streptococcus oralis are ubiquitous oral commensal organisms. Under host-permissive conditions these organisms can form hypervirulent mucosal biofilms. C. albicans biofilm formation is controlled by 6 master transcriptional regulators: Bcr1, Brg1, Efg1, Tec1, Ndt80, and Rob1. The objective of this work was to test whether any of these regulators play a role in cross-kingdom interactions between C. albicans and S. oralis in oral mucosal biofilms, and identify downstream target gene(s) that promote these interactions. Organotypic mucosal constructs and a mouse model of oropharyngeal infection were used to analyze mucosal biofilm growth and fungal gene expression. By screening 6 C. albicans transcription regulator reporter strains we discovered that EFG1 was strongly activated by interaction with S. oralis in late biofilm growth stages. EFG1 gene expression was increased in polymicrobial biofilms on abiotic surfaces, mucosal constructs and tongue tissues of mice infected with both organisms. EFG1 was required for robust Candida-streptococcal biofilm growth in organotypic constructs and mouse oral tissues. S. oralis stimulated C. albicans ALS1 gene expression in an EFG1-dependent manner, and Als1 was identified as a downstream effector of the Efg1 pathway which promoted C. albicans-S. oralis coaggregation interactions in mixed biofilms. We conclude that S. oralis induces an increase in EFG1 expression in C. albicans in late biofilm stages. This in turn increases expression of ALS1, which promotes coaggregation interactions and mucosal biofilm growth. Our work provides novel insights on C. albicans genes which play a role in cross-kingdom interactions with S. oralis in mucosal biofilms.

Efficiency of piezotome-corticision assisted orthodontics in alleviating mandibular anterior crowding-a randomized clinical trial.

OBJECTIVES: The aim of this clinical trial was to investigate the duration of mandibular-crowding alleviation with piezotome-corticision orthodontics compared with conventional orthodontics. DESIGN: Single-centre, two-arm parallel group randomized controlled trial. SETTING: Orthodontic clinic at the University of Connecticut. ETHICAL APPROVAL: The study was approved by the Institutional Review Board (IRB # 12-0147-2). SUBJECTS AND METHODS: Forty-one adult subjects from a single centre with more than 5mm of mandibular anterior crowding were randomly allocated using block randomization into experimental and control groups. The experimental group received a corticision procedure with a piezotome on the labial aspect of the mandibular incisors in conjunction to a self-ligation fixed orthodontic appliance. The control group received the self-ligation fixed orthodontic appliance and no corticision. Same archwire sequence (0.014 inch followed by 0.014 × 0.025 inch copper-nickel-titanium) was followed for both groups. Mandibular study casts taken every 4-5 weeks were used to assess changes in the irregularity index by blinded outcome assessors. OUTCOME MEASURES: The time to alignment was calculated in days. RESULTS: Twenty-nine subjects (16 experimental and 13 control) completed the study. Overall, no significant difference in the time required to correct mandibular crowding with piezotome-corticision assisted (102.1 ± 34.7 days; 95% CI, 83.6 to 120.6) and conventional orthodontics (112 ± 46.2 days; 95% CI, 84-139.9) was observed. No complications with treatment or unintended consequences were observed on any of the subjects. LIMITATIONS: A high attrition rate. CONCLUSIONS: This randomized clinical trial found no evidence that piezotome-corticision assisted orthodontics was more efficient in alleviating mandibular anterior crowding. REGISTRATION: ClinicalTrials.gov, Identifier: NCT02026258. FUNDING: Division of Orthodontics, University of Connecticut. CONFLICT OF INTEREST: None.

Osteogenesis During Early Healing Around Titanium and Roxolid Implants: Evaluation of Bone Markers by Immunohistochemistry and RT-PCR Analysis in Miniature Pigs: A Pilot Study.

PURPOSE: A novel approach for the study of early bone formation around dental implants in the miniature pig was evaluated. In addition to the traditional histologic and histomorphometric analysis, the expression of the osteogenic genes was analyzed both at the messenger ribonucleic acid (mRNA) and protein level. MATERIALS AND METHODS: Mandibular premolars and the first molar were extracted in six miniature pigs. After 3 months of healing, 36 specially designed bone chamber implants were placed. Three different implant surface configurations were used: titanium SLA, titanium SLActive, and titanium zirconium SLActive (Roxolid). Each hemi-mandible received three randomly allocated implants (one for each surface type) on both sides of the arch, in a split-mouth design. Three animals were sacrificed after 3 days and another three after 2 weeks of healing post-implant insertion. For each animal the right hemi-mandible underwent qualitative histologic and quantitative histomorphometric analysis. The left hemi-mandible underwent immunohistofluorescence (IHF) analysis. ß-catenin, Runx2, osteopontin, and osteocalcin were analyzed by IHF; osterix, and osteocalcin mRNA expression was also evaluated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). RESULTS: At 3 days after the implantation, all implants were surrounded by blood clot. No provisional matrix or bone was observed inside the chamber. Infection or degenerative lesions were absent. At 2 weeks, the histomorphometric analysis showed no significant difference between the groups concerning the bone area. qRT-PCR showed that Ti SLActive had the highest osteocalcin mRNA expression followed by Ti SLA and Roxolid SLActive. Osterix mRNA expression was higher on Ti SLA and Roxolid SLActive compared to Ti SLActive. The differences were not statistically significant. IHF was only found positive for osteocalcin at 2 weeks. At 3 days, osteocalcin was detected only on native bone. At 2 weeks, osteocalcin was expressed highest by Ti SLActive followed by Roxolid SLActive and TiSLA; however, there was no statistically significant difference between the groups in the osteocalcin expression level. CONCLUSION: The present methodology allowed evaluation of changes in gene expression during the early phase of osteogenesis that seem to be related to the quality of the surface. Further studies with higher power and more specific antibodies are needed to confirm these preliminary findings.

Streptococcus oralis and Candida albicans Synergistically Activate µ-Calpain to Degrade E-cadherin From Oral Epithelial Junctions.

Streptococcus oralis forms robust mucosal biofilms with Candida albicans that have increased pathogenic potential. In this study, using oral epithelial cultures, organotypic oral mucosal constructs, and a mouse model of oral infection, we demonstrated that S. oralis augmented C. albicans invasion through epithelial junctions. C. albicans and S. oralis decreased epithelial E-cadherin levels by synergistically increasing µ-calpain, a proteolytic enzyme that targets E-cadherin. In the mouse coinfection model this was accompanied by increased fungal kidney dissemination. Coinfection with a secreted aspartyl protease (sap) mutant sap2456 and S. oralis increased µ-calpain and triggered mucosal invasion and systemic dissemination, suggesting that fungal protease activity is not required for invasion during coinfection. We conclude that C. albicans and S. oralis synergize to activate host enzymes that cleave epithelial junction proteins and increase fungal invasion.

Experimental Models of C. albicans-Streptococcal Co-infection.

Interactions of C. albicans with co-colonizing bacteria at mucosal sites can be synergistic or antagonistic in disease development, depending on the bacterial species and mucosal site. Mitis group streptococci and C. albicans colonize the oral mucosa of the majority of healthy individuals. These streptococci have been termed "accessory pathogens," defined by their ability to initiate multispecies biofilm assembly and promote the virulence of the mixed bacterial biofilm community in which they participate. To demonstrate whether interactions with Mitis group streptococci limit or promote the potential of C. albicans to become an opportunistic pathogen, in vitro and in vivo co-infection models are needed. Here, we describe two C. albicans-streptococcal co-infection models: an organotypic oral mucosal tissue model that incorporates salivary flow and a mouse model of oral co-infection that requires reduced levels of immunosuppression compared to single fungal infection.

Candida albicans biofilms do not trigger reactive oxygen species and evade neutrophil killing.

Neutrophils are found within Candida albicans biofilms in vivo and could play a crucial role in clearing the pathogen from biofilms forming on catheters and mucosal surfaces. Our goal was to compare the antimicrobial activity of neutrophils against developing and mature C. albicans biofilms and identify biofilm-specific properties mediating resistance to immune cells. Antibiofilm activity was measured with the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)2H-tetrazolium-5-carboxanilide assay and a molecular Candida viability assay. Reactive oxygen species generation was assessed by measuring fluorescence of 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester in preloaded neutrophils. We found that mature biofilms were resistant to leukocytic killing and did not trigger reactive oxygen species, even though neutrophils retained their viability and functional activation potential. Beta-glucans found in the extracellular matrix negatively affected antibiofilm activities. We conclude that these polymers act as a decoy mechanism to prevent neutrophil activation and that this represents an important innate immune evasion mechanism of C. albicans biofilms.

Synergistic interaction between Candida albicans and commensal oral streptococci in a novel in vitro mucosal model.

Candida albicans is a commensal colonizer of the gastrointestinal tract of humans, where it coexists with highly diverse bacterial communities. It is not clear whether this interaction limits or promotes the potential of C. albicans to become an opportunistic pathogen. Here we investigate the interaction between C. albicans and three species of streptococci from the viridans group, which are ubiquitous and abundant oral commensal bacteria. The ability of C. albicans to form biofilms with Streptococcus oralis, Streptococcus sanguinis, or Streptococcus gordonii was investigated using flow cell devices that allow abiotic biofilm formation under salivary flow. In addition, we designed a novel flow cell system that allows mucosal biofilm formation under conditions that mimic the environment in the oral and esophageal mucosae. It was observed that C. albicans and streptococci formed a synergistic partnership where C. albicans promoted the ability of streptococci to form biofilms on abiotic surfaces or on the surface of an oral mucosa analogue. The increased ability of streptococci to form biofilms in the presence of C. albicans could not be explained by a growth-stimulatory effect since the streptococci were unaffected in their growth in planktonic coculture with C. albicans. Conversely, the presence of streptococci increased the ability of C. albicans to invade organotypic models of the oral and esophageal mucosae under conditions of salivary flow. Moreover, characterization of mucosal invasion by the biofilm microorganisms suggested that the esophageal mucosa is more permissive to invasion than the oral mucosa. In summary, C. albicans and commensal oral streptococci display a synergistic interaction with implications for the pathogenic potential of C. albicans in the upper gastrointestinal tract.

Disruption of the Fgf2 gene activates the adipogenic and suppresses the osteogenic program in mesenchymal marrow stromal stem cells.

Here we determine the Fibroblast Growth Factor-2 (FGF2) dependency of the time course of changes in bone mass in female mice. This study extends our earlier reports that knockout of the FGF2 gene (Fgf2) caused low turnover bone loss in Fgf2(-/-) male mice by examining bone loss with age in Fgf2(-/-) female mice, and by assessing whether reduced bone formation is associated with differentiation of bone marrow stromal cells (BMSCs) towards the adipocyte lineage. Bone mineral density (BMD) was similar in 3-month-old female Fgf2(+/+) and Fgf2(-/-) mice but was significantly reduced as early as 5 months of age in Fgf2(-/-) mice. In vivo studies showed that there was a greater accumulation of marrow fat in long bones of 14 and 20 month old Fgf2(-/-) mice compared with Fgf2(+/+) littermates. To study the effect of disruption of FGF2 on osteoblastogenesis and adipogenesis, BMSCs from both genotypes were cultured in osteogenic or adipogenic media. Reduced alkaline phosphatase positive (ALP), mineralized colonies and a marked increase in adipocytes were observed in Fgf2(-/-) BMSC cultures. These cultures also showed an increase in the mRNA of the adipogenic transcription factor PPARgamma2 as well as the downstream target genes aP2 and adiponectin. Treatment with exogenous FGF2 blocked adipocyte formation and increased ALP colony formation and ALP activity in BMSC cultures of both genotypes. These results support an important role for endogenous FGF2 in osteoblast (OB) lineage determination. Alteration in FGF2 signaling may contribute to impaired OB bone formation capacity and to increased bone marrow fat accumulation both of which are characteristics of aged bone.

Lipopolysaccharide-mediated enhancement of bone metabolism in estrogen-deficient mice.

BACKGROUND: Osteoporosis may be a risk factor in periodontal disease. However, biologic mechanisms explaining the apparent interaction between these two diseases have not been defined. It is well known that lipopolysaccharide (LPS) increases the resorption of alveolar bone. We hypothesized that LPS and estrogen deficiency have synergistic effects on bone metabolism and may lead to enhanced bone resorption. METHODS: Eighty 8-week-old female ddY mice were divided into two groups and underwent a sham operation or bilateral ovariectomy. They were maintained for 4 weeks to assess estrogen-deficient bone loss. Osteoblasts and bone marrow cells (BMCs) were collected from ovariectomized (OVX) and sham-operated mice. Osteoclast differentiation in a coculture of osteoblasts and BMCs was investigated by tartrate-resistant acid phosphatase staining. Receptor activator of nuclear factor-kappa B ligand (RANKL) mRNA expression in LPS-treated osteoblasts was investigated using real-time polymerase chain reaction. Interferon-gamma (IFN-gamma) and interleukin (IL)-6 and -10 levels in the culture supernatants were evaluated by enzyme-linked immunosorbent assay. Group means were compared by analysis of variance followed by Tukey's honestly significant difference. RESULTS: There was a significant increase in the number of osteoclasts in LPS-treated cocultures from OVX mice compared to sham controls (P <0.05). RANKL mRNA expression in LPS-treated osteoblasts from OVX mice was greater than in sham mice (P <0.05). In contrast, the production of IFN-gamma in LPS-treated coculture from OVX mice was significantly lower than in sham mice (P <0.05). CONCLUSION: LPS-bearing Gram-negative organisms are abundant in periodontal disease, and the results supported the hypothesis that bone resorption is increased in estrogen-deficient patients.

Impaired osteoclast formation in bone marrow cultures of Fgf2 null mice in response to parathyroid hormone.

Fibroblast growth factor (FGF)-2 and parathyroid hormone (PTH) are potent inducers of osteoclast (OCL) formation, and PTH increases FGF-2 mRNA and protein expression in osteoblasts. To elucidate the role of endogenous FGF-2 in PTH responses, we examined PTH-induced OCL formation in bone marrow cultures from wild type and mice with a disruption of the Fgf2 gene. FGF-2-induced OCL formation was similar in marrow culture from both genotypes. In contrast, PTH-stimulated OCL formation in bone marrow cultures or co-cultures of osteoblast-spleen cells from Fgf2-/mice was significantly impaired. PTH increased RANKL mRNA expression in osteoblasts cultures from both genotypes. After 6 days of treatment, osteoprotegerin protein in cell supernatants was 40-fold higher in vehicle-treated and 30-fold higher in PTH-treated co-cultures of osteoblast and spleen cells from Fgf2-/mice compared with Fgf2+/+ mice. However, a neutralizing antibody to osteoprotegerin did not rescue reduced OCL formation in response to PTH. Injection of PTH caused hypercalcemia in Fgf2+/+ but not Fgf2-/mice. We conclude that PTH stimulates OCL formation and bone resorption in mice in part by endogenous FGF-2 synthesis by osteoblasts. Because RANKL- and interleukin-11-induced OCL formation was also reduced in bone marrow cultures from Fgf2-/mice, we further conclude that endogenous FGF-2 is necessary for maximal OCL formation by multiple bone resorbing factors.