Soy isoflavones alleviate periodontal destruction in ovariectomized rats

OBJECTIVE

The purpose of this study was to investigate whether soy isoflavone supplementation is effective in preventing periodontal destruction exacerbated by estrogen deficiency (ED) and its potential mechanism.

BACKGROUND

The progression of periodontitis is affected by host factors, such as smoking, diabetes mellitus, and steroid use. Bone loss in periodontitis can be aggravated by ED.

METHODS

A rat model of experimental periodontitis (EP) with ED was established by silk ligature and inoculation with Porphyromonas gingivalis, and some EP rats were subjected to bilateral ovariectomy (OVX). The treatment groups received an intravenous injection of 17-β-estradiol (E₂ B) or soy isoflavones (SI) by gavage. The rats were euthanized, and the maxillary jaws, gingiva, and serum were harvested. Tight junction protein and interleukin (IL)-17 expression, reactive oxygen species (ROS) level, and periodontal destruction were assessed. In addition, we determined whether grainyhead-like 2 (GRHL2) is required for enhancing the epithelial barrier by SI in an in vitro P. gingivalis infection model.

RESULTS

Estrogen deficiency impaired the expression of genes encoding tight junction proteins in the gingiva, increased IL-17 level, and accelerated alveolar bone resorption. SI treatment alleviated tight junction protein expression, decreased IL-17 and ROS levels, and prevented the absorption of alveolar bone. Furthermore, GRHL2 expression was significantly induced by SI in human oral keratinocytes-1 (HOK-1) cells; GRHL2 knockdown impaired the expression of OCLN and ZO-1 induced by SI treatment.

CONCLUSION

Soy isoflavones alleviates periodontitis in OVX rats, as observed by the increased expression of tight junction proteins, and reduced IL-17 level and alveolar bone loss. The in vitro studies suggested that the enhancement of oral epithelial barrier by SI treatment was partially dependent on GRHL2.

The Effect of Menopause Hypoestrogenism on Osteogenic Differentiation of Periodontal Ligament Cells (PDLC) and Stem Cells (PDLCs): A Systematic Review

(1) Background: Menopause is a physiological condition typified by drastic hormonal changes, and the effects of this transition have long-term significant clinical implications on the general health, including symptoms or physical changes. In menopausal women, the periodontium can be affected directly or through neural mechanism by oestrogen (E2) deficiency. The majority of the biological effects of E2 are modulated via both oestrogen receptor-α (ERα) and oestrogen receptor- β (ERβ). There is evidence that hypoestrogenism has a substantial impact on the aetiology, manifestation and severity of periodontitis, via the regulation of the expression of osteoprogesterin and RANKL in human periodontal ligament cells through ERβ. However, the mechanistic understanding of oestrogen in periodontal status has been partially clarified. The aim of this paper was to synopsize the recent scientific evidence concerning the link between the menopause and periodontitis, through the investigation of physio-pathological impact of the oestrogen deficiency on osteogenic differentiation of PDLSCs and PDLSC, as well as the dynamic change of ERα and ERβ. (2) Methods: Search was conducted for significant studies by exploring electronic PubMed and EMBASE databases, and it was independently performed by two researchers. All studies on the impact of oestrogen level on alveolar bone resorption were searched from 2005 to July 2020. Data selection was in concordance with PRISMA guidelines. (3) Results: Eight studies met the criteria and were included in this systematic review. All studies reported that oestrogen deficiency impairs the osteogenic and osteoblastic differentiation of PDL cells and oestrogen affects the bone formation capacity of cells. Seven studies were conducted on animal samples, divided into two groups: the OVX animals and animals who received the sham operation. (4) Conclusions: There is a multitude of data available showing the influence of menopause on periodontal status. However, the evidence of this line to investigation needs more research and could help explain the physiological linkage between menopause state and periodontal disease.

Effect of Periodontal Pathogens on Total Bone Volume Fraction: A Phenotypic Study

Studies have shown that periodontal pathogens can enter the bloodstream, causing a series of reactions that can lead to a variety of systemic diseases. Epidemiological investigations also found a tight correlation between periodontitis (PD) and osteoporosis. This study aimed to further explore the effect of periodontal pathogens on bone volume fraction like bone tissue and mass, and explain the relationship between PD and osteoporosis. Sprague Dawley rats (female, 16 weeks old) were divided into the wild-type (WT) control group (n=9) and PD group (n=9). After eight weeks, periodontal tissues and ligatures, the fourth lumbar vertebra, the femur, the tibia, and blood were extracted and analyzed by micro-computed tomography (micro-CT), hematoxylin and eosin (H&E) staining, tartrate-resistant acid phosphatase (TRAP) staining, polymerase chain reaction (PCR), and enzyme-linked immunoassay (ELISA), respectively. We found that the bone mass of the lumbar vertebra, femur, and tibia was decreased in the PD group. The number of osteoclasts was higher in bone tissue in the PD group than in the WT group (P<0.05). The levels of inflammatory mediators and type I collagen C-terminal peptide (CTX-1) were higher in the PD group than in the WT group (P<0.05), although no significant difference in bone glutamic acid protein (BGP) levels was observed (P>0.05). In addition, we detected several periodontal pathogens, such as Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, and Fusobacterium nucleatum, in blood samples from rats in the PD group. These findings suggest that periodontal pathogens can enter the blood circulation from periodontal tissue, promote a systemic inflammation response, and subsequently reduce systemic bone density.

The opposite effects of Antarctic krill oil and arachidonic acid-rich oil on bone resorption in ovariectomized mice

The opposite effects and mechanism of AKO and AAO in the regulation of bone resorption in postmenopausal osteoporosis were systematically investigated to support the recommendations on fatty acid types in dietary oils for people with osteoporosis.

Do Patients with Osteoporosis Have Higher Risk to Present Reduced Alveolar Ridge Height? An Imaging Analysis

Background

Osteoporosis and periodontitis are both diseases that induce bone resorption. The objective of this study was to verify through panoramic radiography analysis whether patients with osteoporosis have a greater risk of periodontal disease (horizontal alveolar bone defect and vertical alveolar bone defect) when compared with patients without osteoporosis.

Methods

In all, 100 women were selected: 50 with osteoporosis (T-score < -2.5 DP) and 50 without osteoporosis (T-score > -2.5 DP), using the T-score of proximal radius. Logistic regression test was performed to assess the risk of panoramic radiographic periodontal defects (horizontal and vertical bone defect), age, and bone mineral density influence.

Results

Advanced age women were three times more likely to present osteoporosis. Patients with osteoporosis have significantly higher risk (4.46 times) of presenting horizontal alveolar bone defect. Vertical alveolar bone defect results were nonsignificant.

Conclusion

Our study results corroborate the literature trend that osteoporosis may influence the progression of alveolar ridge height loss (horizontal alveolar bone defect). Panoramic radiography may be used as a screening tool to help the diagnosis of periodontal bone loss in patients with osteoporosis.

Toxicologic Pathology Forum: Current Status on the Use of Animal Models of Human Disease in the Pharmaceutical Industry in Japan in Nonclinical Safety Assessment-Opinion Paper

In nonclinical safety studies for new drug development, healthy animals have been commonly used. However, in some cases, the use of animal models of human disease is considered to be more favorable in evaluating risks in patients. To elucidate the current status of the use of animal models for nonclinical safety assessment, an internal questionnaire from the Japan Pharmaceutical Manufacturers Association and surveys (questionnaire period: August 27 to September 30, 2015) of both common technical documents and review reports of approved drugs (approval period: May 1999 to May 2017) disclosed by the Pharmaceutical and Medical Devices Agency were conducted. Although there were some concerns and limitations raised, the survey results revealed that animal models have been used in nonclinical safety assessment on a case-by-case basis and that nonclinical safety studies using animal models were included in the data packages of several approved drugs in Japan. The survey results also revealed that nonclinical safety studies using animal models have become more frequent in the past few years. In almost all cases, useful information, such as signs of toxicity under disease conditions and mechanisms of toxic change, was obtained from the results of nonclinical studies using animal models. Note: This is an opinion article submitted to the Toxicologic Pathology Forum. It represents the views of the author(s). It does not constitute an official position of the Society of Toxicologic Pathology, British Society of Toxicological Pathology, or European Society of Toxicologic Pathology, and the views expressed might not reflect the best practices recommended by these Societies. This article should not be construed to represent the policies, positions, or opinions of their respective organizations, employers, or regulatory agencies.

Respective role of membrane and nuclear estrogen receptor (ER) α in the mandible of growing mice: Implications for ERα modulation

Estrogens play an important role in bone growth and maturation as well as in the regulation of bone turnover in adults. Although the effects of 17β-estradiol (E2) are well documented in long bones and vertebrae, little is known regarding its action in the mandible. E2 actions could be mediated by estrogen receptor (ER) α or β. ERs act primarily as transcriptional factors through two activation functions (AFs), AF1 and AF2, but they can also elicit membrane-initiated steroid signaling (MISS). The aim of the present study was to define ER pathways involved in E2 effects on mandibular bone. Using mice models targeting ERβ or ERα, we first show that E2 effects on mandibular bone are mediated by ERα and do not require ERβ. Second, we show that nuclear ERαAF2 is absolutely required for all the actions of E2 on mandibular bone. Third, inactivation of ERαMISS partially reduced the E2 response on bone thickness and volume, whereas there was no significant impact on bone mineral density. Altogether, these results show that both nuclear and membrane ERα are requested to mediate full estrogen effects in the mandible of growing mice. Finally, selective activation of ERαMISS is able to exert an effect on alveolar bone but not on the cortical compartment, contrary to its protective action on femoral cortical bone. To conclude, these results highlight similarities but also specificities between effects of estrogen in long bones and in the mandible that could be of interest in therapeutic approaches to treat bone mass reduction. © 2018 American Society for Bone and Mineral Research.

Raloxifene reduces the risk of local alveolar bone destruction in a mouse model of periodontitis combined with systemic postmenopausal osteoporosis

OBJECTIVE

Periodontitis is characterized by local inflammation leading to tooth loss and severe destruction of alveolar bone. Raloxifene is a selective estrogen receptor modulator (SERM) that halts estrogen deficiency-induced systemic bone loss in postmenopausal osteoporosis without the side effects of cancer in breast and uterus. In this study, we examined the effects of raloxifene on alveolar bone mass in a mouse model with estrogen deficiency-induced periodontitis.

METHODS

Periodontitis was induced by the injection of lipopolysaccharide (LPS) into the lower gingiva in ovariectomized (OVX) mice, and the alveolar bone and femur bone mineral density (BMD) were analyzed by dual-energy X-ray absorptiometry. To explore the direct osteoclast inhibitory effect of raloxifene, a co-culture system for osteoclast formation and organ culture of alveolar bone was established.

RESULTS

When OVX mice were treated with raloxifene, the bone loss in both alveolar bone and femur were abrogated. Interleukin 1 and/or LPS stimulated the osteoclast formation and bone-resorbing activity; however, raloxifene did not show any inhibitory effect on the osteoclast formation or function. In vivo local injection of raloxifene also did not prevent bone resorption in a mouse model of periodontitis. However, the systemic treatment of raloxifene using a mini-osmotic pump did prevent the loss of BMD of alveolar bone induced by LPS.

CONCLUSION

These results suggest that the SERM raloxifene systemically maintain alveolar bone mass in a mouse model of periodontitis with osteoporosis. Increasing the alveolar bone mass by SERMs treatment in patients with postmenopausal osteoporosis may be a useful approach to preventing the destruction of alveolar bone in late-onset periodontitis.

Leptin Overexpression in Bone Marrow Stromal Cells Promotes Periodontal Regeneration in a Rat Model of Osteoporosis

BACKGROUND

Osteoporosis is associated with widespread periodontitis and impaired periodontal healing. However, there is a lack of information about the outcomes of regenerative approaches under the influence of osteoporosis. This study investigates the effect of leptin (LEP) overexpression on the regenerative potential of bone marrow stromal cells (BMSCs) in an osteoporotic rat periodontal fenestration defect model.

METHODS

Rat BMSCs were transfected with adenoviruses harboring the human (h)LEP gene. Cell proliferation and osteogenic differentiation were evaluated. A β-tricalcium phosphate scaffold seeded with transfected cells was implanted into nude mice to investigate ectopic osteogenesis and into an osteoporotic rat defect to study periodontal regeneration. Regenerated periodontal and bone-like tissues were analyzed by histologic methods.

RESULTS

hLEP overexpression induced osteogenic differentiation of BMSCs as evidenced by the upregulation of osteogenesis-related genes such as Runt-related transcription factor 2, alkaline phosphatase (ALP), and collagen Type I, as well as increased ALP activity and enhanced mineralization. Mice implanted with hLEP-BMSC-containing scaffolds showed more extensive formation of bone-like tissue than those in other groups. Periodontal defects were also filled to a greater degree when treated with hLEP-BMSCs and contained cementum and a well-organized periodontal ligament after 10 and 28 days.

CONCLUSION

hLEP overexpression in BMSCs can stimulate periodontal regeneration in osteoporotic conditions and might be a promising strategy for periodontal regeneration in patients with osteoporosis.

Aromatase deficiency in a male patient - Case report and review of the literature

OBJECTIVE

Aromatase, or CYP19A1, is a type II cytochrome CYP450 enzyme that catalyzes the conversion of C19 androgens to C18 estrogens. Its crucial role in both female and male physiology has been deduced from human and animal studies using aromatase inhibitors, genetically altered mice, and patients with aromatase deficiency. The latter is an extremely rare disorder. Its diagnosis is particularly difficult in males, who go through puberty normally and therefore usually present as adults with elevated testosterone, bone abnormalities (e.g., delayed bone age and low bone mass), and metabolic syndrome. In this report, we describe a new case of a male patient with aromatase deficiency harboring a known mutation who presented with less severe clinical and biochemical features.

CASE REPORT

The patient presented with low bone mass and delayed bone age after a finger fracture at age 25years. FSH, LH and testosterone levels were normal, but estradiol and estrone levels were absent or barely detectable, raising suspicion for aromatase deficiency. A homozygous c.628G>A mutation in exon 5 was confirmed by direct sequencing. Unlike previously reported cases of aromatase deficiency, he did not display biochemical features of insulin resistance, dyslipidemia, or overweight/obese status. Therapy with estradiol led to the closure of growth plates and a dramatic increase in bone mass.

CONCLUSIONS

Here we explore genotype/phenotype associations of this new case compared to cases reported previously. We conclude that the specific nature of mutation c.628G>A, which can potentially result in several different forms of the aromatase enzyme, may lend an explanation to the variable phenotypes associated with this particular genotype.

The effect of boron on alveolar bone loss in osteoporotic rats

BACKGROUND/PURPOSE

The aim of this study is to investigate the effects of systemically administered boric acid on osteoporosis-related bone alterations, alveolar bone loss, receptor activator of nuclear factor kappa-b ligand (RANKL) expressions, and mandibular bone density in experimental periodontitis model in osteoporotic rats.

MATERIALS AND METHODS

Thirty-six male Wistar rats were separated into five study groups: nonligated control (C, n = 6) group; periodontitis (P, n = 6) group; osteoporosis (O, n = 8) group; osteoporosis + periodontitis (O+P, n = 8) group, and osteoporosis + periodontitis with 50 mg/kg/d boric acid (BA50, n = 8) group for 15 days. Osteoporosis was created with intraperitoneal injection of 80 mg/kg retinoic acid for 15 days. Silk ligatures (4/0) were placed around the mandibular right first molar teeth to induce experimental periodontitis. After induction of osteoporosis and periodontitis, rats were sacrificed at Day 15. Alveolar bone loss was evaluated with a stereomicroscope by measuring the distance from the cement-enamel junction to the alveolar crest. Density measurements were performed on radiographs. RANKL and tartrate-resistant acid phosphatase (TRAP) staining were performed on histological slides.

RESULTS

Alveolar bone loss was significantly higher in the O+P group than those of the other groups (P < 0.05). Boric acid decreased bone loss (P < 0.05). TRAP + osteoclast numbers were highest in the P group and lowest in the control group. The differences in TRAP + osteoclast numbers among control, P, O+P, and BA50 groups were significant (P < 0.05). There were no significant differences in RANKL expression and mandibular bone density (P > 0.05).

CONCLUSION

Within limitations of this study, we conclude that boric acid may decrease alveolar bone loss in a rat model with periodontitis and osteoporosis.

Estrogen enhances the bone regeneration potential of periodontal ligament stem cells derived from osteoporotic rats and seeded on nano-hydroxyapatite/collagen/poly(L-lactide)

This study investigated the effects of estrogen on the bone regeneration potential of periodontal ligament stem cells (PDLSCs) derived from osteoporotic rats and seeded on a collagen-based composite scaffold [nano-hydroxyapatite/collagen/poly(L-lactide) (nHAC/PLA)]. For this purpose, 48 healthy 3‑month-old Sprague-Dawley female rats were divided into 2 groups as follows: the bilaterally ovariectomized (OVX) rats and sham‑operated rats. The PDLSCs were isolated at 3 months after surgery (by which time postmenopausal osteoporosis had developed). The effects of estrogen on the characteristics of these cells seeded in a culture plate and of the cells seeded on nHAC/PLA were then investigated. The PDLSC + nHAC/PLA constructs were implanted subcutaneously into the backs of severe combined immunodeficient (SCID) mice for 12 weeks in order to examine the role of estrogen in the bone formation ability of PDLSCs derived from osteoporotic rats. The results from methyl thiazolyl tetrazolium (MTT) assay revealed that the proliferation of the cells derived from the rats in the OVX group was significantly higher than that of the cells derived from the rats in the sham-operated group at the stage of logarithmic growth. The staining intensity of alkaline phosphatase (ALP) and the mineralization of the cells derived from the rats in the OVX group was significantly weaker than that of the cells from the rats in the sham-operated group. When the PDLSCs were seeded on nHAC/PLA, ALP activity, osteocalcin (OCN) secretion, mineral formation and the mRNA expression levels of ALP, OCN, estrogen receptor (ER)α and ERβ in the cells derived from the rats in the OVX group were markedly decreased. Treatment with 17β-estradiol (E2) significantly weakened the proliferative ability of the cells derived from the OVX group rats, and enhanced their osteogenic differentiation ability and the mRNA expression levels of ALP, OCN, ERα and ERβ. When the constructs were implanted into the backs of SCID mice for 12 weeks, the results of histological analysis indicated that the constructs derived from the OVX group rats had a few newly formed bones and osteoids; however, a great number of newly formed bones and osteoids were present in the ones from the sham-operated group and the OVX + E2 group rats. Our findings further indicate that estrogen deficiency impairs the osteogenic differentiation potential of PDLSCs, and that ER plays an important role in the bone regeneration ability of PDLSCs. Estrogen enhances the bone regeneration potential of PDLSCs derived from osteoporotic rats and seeded on nHAC/PLA. This study may provide insight into the clinical management of periodontal bone tissue repair in postmenopausal women with the use of estrogen-mediated PDLSCs seeded on nHAC/PLA.

Myricetin Prevents Alveolar Bone Loss in an Experimental Ovariectomized Mouse Model of Periodontitis

Periodontitis is a common chronic inflammatory disease, which leads to alveolar bone resorption. Healthy and functional alveolar bone, which can support the teeth and enable their movement, is very important for orthodontic treatment. Myricetin inhibited osteoclastogenesis by suppressing the expression of some genes, signaling pathways, and cytokines. This study aimed to investigate the effects of myricetin on alveolar bone loss in an ovariectomized (OVX) mouse model of periodontitis as well as in vitro osteoclast formation and bone resorption. Twenty-four healthy eight-week-old C57BL/J6 female mice were assigned randomly to four groups: phosphate-buffered saline (PBS) control (sham) OVX + ligature + PBS (vehicle), and OVX + ligature + low or high (2 or 5 mg∙kg⁻¹∙day⁻¹, respectively) doses of myricetin. Myricetin or PBS was injected intraperitoneally (i.p.) every other day for 30 days. The maxillae were collected and subjected to further examination, including micro-computed tomography (micro-CT), hematoxylin and eosin (H&E) staining, and tartrate-resistant acid phosphatase (TRAP) staining; a resorption pit assay was also performed in vitro to evaluate the effects of myricetin on receptor activator of nuclear factor κ-B ligand (RANKL)-induced osteoclastogenesis. Myricetin, at both high and low doses, prevented alveolar bone resorption and increased alveolar crest height in the mouse model and inhibited osteoclast formation and bone resorption in vitro. However, myricetin was more effective at high dose than at low dose. Our study demonstrated that myricetin had a positive effect on alveolar bone resorption in an OVX mouse model of periodontitis and, therefore, may be a potential agent for the treatment of periodontitis and osteoporosis.

Periodontal disease exacerbates systemic ovariectomy-induced bone loss in mice

Periodontal pathogens and/or inflammatory products from periodontitis participate in the development or progression of systemic diseases. In this context, periodontitis acts as a modifying factor to systemic health, including diabetes and cardiovascular diseases. Osteoporosis is an increasingly prevalent condition in our aging population and considered a risk factor for periodontal disease, but the effect of periodontitis on systemic bone homeostasis is unknown. We thus evaluated the effects of experimental periodontitis (EP) on systemic bone loss and the influence of estrogen deficiency in this context, using a mouse model of combined periodontitis and osteoporosis. Experimental periodontitis (EP) was induced by a ligature insertion around the mandibular first molars and Porphyromonas gingivalis infection. Three-dimensional microcomputed tomographic analyses performed 48days following infection revealed that EP and ovariectomy (OVX) induced a significantly higher femoral and mandibular bone loss compared to EP or OVX alone. EP alone did not induce systemic bone loss. In addition, the EP+OVX and EP groups showed significantly higher levels of tumor necrosis factor (TNF)-α than OVX and control groups at end point. These results suggest that periodontitis could be a risk factor for systemic bone loss, especially in post-menopausal women, and warrant further clinical investigations to confirm this association and propose adapted prophylactic and curative therapies.

Oestrogen regulates bone resorption and cytokine production in the maxillae of female mice

Oestrogen plays major role in bone metabolism/remodelling. Despite of well-established effect of oestrogen deficiency on long bones, it remains unclear whether alveolar bone is affected. We aimed to determine the effect of oestrogen-deficiency in the alveolar bone microarchitecture. C57BL6/J and Balb/c mice were ovariectomized and implanted with oil-(OVX) or 17β-estradiol (E2)-containing (OVX+E2) capsules. Ovary-intact mice were used as controls. The dose of E2 replacement was selected based on trophic effects on the uterus and femur bone loss. As determined by maxillary alveolar bone MicroCT analysis, both C57BL6/J and Balb/c OVX mice displayed decreased trabecular thickness, bone density and bone volume, and increased trabecular separation at 15 and 30 days after ovariectomy. These effects were associated with a reduction of trabecular bone percentage and cortical thickness in the femur. A significant loss of alveolar bone crest was also associated with ovariectomy in both mice strains. The E2 replacement fully prevented ovariectomy-induced alterations in the alveolar and femoral bones. Moreover, TNF-α (tumour necrosis factor-α) levels and RANKL/OPG (receptor activator of NF-κB ligand/osteoprotegerin) ratio were increased in the maxilla after OVX, and these responses were also reversed by E2. In conclusion, oestrogen deficiency causes maxillary alveolar bone loss, which is similar to the effects found in the femur. The release of inflammatory molecules like TNF-α, RANKL and OPG is the potential mechanism to the decrease of bone quality and alveolar bone crest.

Whole Body Vibration Reduces Inflammatory Bone Loss in a Lipopolysaccharide Murine Model

Whole body vibration (WBV) stimulation has a beneficial effect on the recovery of osteoporotic bone. We aimed to investigate the immediate effect of WBV on lipopolysaccharide (LPS)-mediated inflammatory bone loss by varying the exposure timing. Balb/C mice were divided into the following groups: control, LPS (L), and LPS with vibration (LV). The L and LV groups received LPS (5 mg/kg) by 2 intraperitoneal injections on days 0 and 4. The LV group was exposed to WBV (0.4 g, 45 Hz) either during LPS treatment (LV1) or after cessation of LPS injection (LV2) and then continued WBV treatment for 10 min/d for 3 d. Evaluation based on micro-computed tomography was performed 7 d after the first injection, when the L group showed a significant decrease in bone volume (-25.8%) and bone mineral density (-33.5%) compared with the control group. The LV2 group recovered bone volume (35%) and bone mineral density (19.9%) compared with the L group, whereas the LV1 group showed no improvement. This vibratory signal showed a suppressive effect on the LPS-mediated induction of inflammatory cytokines such as IL-1β or TNF-α in human mesenchymal stem cells in vitro. These findings suggest that immediate exposure to WBV after the conclusion of LPS treatment efficiently reduces trabecular bone loss, but WBV might be less effective during the course of treatment with inflammatory factor.

Alcoholic and isocaloric diet, but not ovariectomy, influence the apoptosis of bone cells within the alveolar bone crest of rats

OBJECTIVE

Studies suggest that chronic alcoholism as well as oestrogen deficiencies may affect bones in general, including alveolar bone and, by doing so, increase individuals' susceptibility to develop progressive periodontal disease. This paper aims to verify the influence of chronic alcoholism and/or oestrogen deficiencies in the apoptosis of bone cells of the alveolar bone crest region in rats.

DESIGN

Initially, 54 rats were divided into ovariectomized (Ovx) and Sham operated (Sham) groups. Thirty days after surgery, these two groups were equally sub-divided, and received, for 56 days, the following dietary intervention: alcoholic diet (with 20% alcohol solution,), isocaloric diet and ad libitum diet (free diet). Analysis was undertaken by immunohistochemistry, using an antibody to detect apoptosis (anti PARP p-85).

RESULTS

When comparing the six experimental groups, no significant differences were observed in the apoptosis of bone cells. Also, there was no significant difference in the quantity of cells undergoing apoptosis when the animals from Ovx groups were compared with those from Sham groups. However, when comparing only different dietary groups, differences were observed between the groups ad libitum and isocaloric, to osteoblasts (p=0.045); and ad libitum and alcohol, to osteocytes (p=0.007).

CONCLUSION

It is concluded that ovariectomy was not able to influence the rate of apoptosis of bone cells of the alveolar bone crest region in rats and that a possible influence of diet on apoptosis of osteoblasts and osteocytes cannot be ruled out.

Re-evaluating the role of vitamin D in the periodontium

The importance of vitamin D in maintaining skeletal health via the regulation of calcium has long been recognized as a critical function of this secosteroid. An abundance of literature shows an association between oral bone mineral density and some measure of systemic osteoporosis and suggests that osteoporosis/low bone mass may be a risk factor for periodontal disease. Recently, nonskeletal functions of vitamin D have gained notoriety for several reasons. Many cells that are not associated with calcium homeostasis have been demonstrated to possess membrane receptors for vitamin D. These include activated T and B lymphocytes, and skin, placenta, pancreas, prostate and colon cancer cells. In addition, vitamin D "insufficiency" is a worldwide epidemic and epidemiologic evidence has linked this condition to multiple chronic health problems, including cardiovascular and autoimmune diseases, hypertension and a variety of cancers. Interestingly, there is mounting evidence connecting diminished serum levels of vitamin D with increased gingival inflammation and supporting the concept of "continual vitamin D sufficiency" in maintaining periodontal health. The ability of vitamin D to regulate both the innate and the adaptive components of the host response may play an important role in this process. This review will examine the skeletal and nonskeletal functions of vitamin D, and explore its potential role in protecting the periodontium as well as in regulating periodontal wound healing.

Vitamin D inhibits the expression of interleukin-8 in human periodontal ligament cells stimulated with Porphyromonas gingivalis

OBJECTIVE

Vitamin D has been known to be closely associated with periodontitis while the exact mechanisms remain unclear. The present study aimed to discover the effects of 1a,25-dihydroxyvitamin D3 (1,25D) on the expressions of interleukin (IL)-6 and IL-8 in human periodontal ligament cells (hPDLCs) stimulated with Porphyromonas gingivalis (P. gingivalis) W83.

DESIGN

Primary cultures of hPDLCs from ten donors were established and the cells of passage four were treated with 1,25D or P. gingivalis individually or 1,25D combined with P. gingivalis. The levels of IL-6 and IL-8 protein in hPDLCs were detected with enzyme-linked immunosorbent assay (ELISA) and the mRNA levels were detected with real-time RT-PCR.

RESULTS

P. gingivalis significantly promoted the protein expressions of IL-6 and IL-8. P. gingivalis at the multiplicity of infection (MOI) 100 exerted the strongest promotion effect on the IL-6 protein expression by 5.83-fold compared with the controls (2482.88±26.53pg/ml versus 425.80±77.25pg/ml, P<0.0005) and the IL-8 protein expression by 12.39-fold (4965.81±1072.55pg/ml versus 400.75±2.27pg/ml, P=0.005) in hPDLCs at 24h. At 48h, 10(-8)mol/L 1,25D had the best inhibition on the IL-8 protein expression in hPDLCs by 2.00-fold compared with the controls (100.76±21.11pg/ml versus 201.75±18.15pg/ml, P<0.0005) and the IL-8 mRNA expression by 2.13-fold (P<0.0005). 10(-8)mol/L 1,25D combined with P. gingivalis (MOI 100) exerted the strongest inhibition effect on the IL-8 protein expression by 1.54-fold compared with P. gingivalis treatment alone (3077.33±210.04pg/ml versus 4738.24±1386.17pg/ml, P=0.018) and the IL-8 mRNA expression by 1.78-fold (P=0.012) in hPDLCs at 12h. 1,25D did not influence the expression of IL-6 in hPDLCs with or without P. gingivalis treatment.

CONCLUSION

Vitamin D may potentially inhibit the periodontal inflammation induced by P. gingivalis partly by decreasing the IL-8 expression in hPDLCs.