Inflammation-induced Bone Remodeling in Periodontal Disease and the Influence of Post-menopausal Osteoporosis

Olink Proteomics for the Identification of Biomarkers for Early Diagnosis of Postmenopausal Osteoporosis

This investigation aims to employ Olink proteomics in analyzing the distinct serum proteins associated with postmenopausal osteoporosis (PMOP) and identifying prognostic markers for early detection of PMOP via molecular mechanism research on postmenopausal osteoporosis. Postmenopausal women admitted to Beijing Jishuitan Hospital were randomly selected and categorized into three groups based on their dual-energy X-ray absorptiometry (DXA) T-scores: osteoporosis group (n = 24), osteopenia group (n = 20), and normal bone mass group (n = 16). Serum samples from all participants were collected for clinical and bone metabolism marker measurements. Olink proteomics was utilized to identify differentially expressed proteins (DEPs) that are highly associated with postmenopausal osteoporosis. The functional analysis of DEPs was performed using Gene Ontology and Kyto Encyclopedia Genes and Genomes (KEGG). The biological characteristics of these proteins and their correlation with PMOP were subsequently analyzed. ROC curve analysis was performed to identify potential biomarkers with the highest diagnostic accuracy for early stage PMOP. Through Olink proteomics, we identified five DEPs highly associated with PMOP, including two upregulated and three downregulated proteins. TWEAK and CDCP1 markers exhibited the highest area under the curve (0.8188 and 0.8031, respectively). TWEAK and CDCP1 have the potential to serve as biomarkers for early prediction of postmenopausal osteoporosis.

Changes in biomarkers levels from gingival crevicular fluid in pre- and postmenopausal women undergoing orthodontic treatment : A systematic review

PURPOSE

This study aimed to verify whether there is a difference in biomarker levels in the gingival crevicular fluid between premenopausal and postmenopausal women undergoing orthodontic treatment.

METHODS

As eligibility criteria, prospective or retrospective observational studies evaluating women undergoing orthodontic treatment (P), comparing postmenopausal (E) and premenopausal (C) women, and analyzing differences in gingival crevicular fluid biomarkers (O) were included. An electronic search was conducted in seven databases (PubMed, Scopus, Web of Science, LILACS, The Cochrane Library, Embase, and EBSCO: Dentistry & Oral Science) and one grey literature source (Google Scholar). All databases were searched from September 2022 to March 2023. After duplicate exclusion and data extraction, the Newcastle-Ottawa scale was applied to assess the quality and risk of bias, and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) tool was used to verify the certainty of evidence.

RESULTS

Three case-control studies that analyzed receptor activator of nuclear factor kappa‑B ligand (RANKL), osteopontin (OPN), and interleukin (IL)-17A levels were included. One study reported a significant difference for RANKL and another for OPN levels. A third study reported that there was a higher expression of IL17‑A in the postmenopausal group. However, the small number of articles limits our systematic review. The heterogeneity and imprecision in the study results cast doubt on the findings' internal validity.

CONCLUSION

The studies reported alterations in biomarker levels but differed in their conclusions. Therefore, further studies must include other types of bone and inflammatory biomarkers in female patients who are pre- or postmenopausal and undergoing orthodontic treatment.

REGISTRATION

The review was registered at the Open Science Framework ( https://doi.org/10.17605/OSF.IO/Q9YZ8 ).

Morphometric analysis of bony nasolacrimal canal and sinonasal anatomical variations in primary acquired nasolacrimal duct obstruction

OBJECTIVE

This study aims to assess morphometric variations in bony nasolacrimal ducts (BNLDs) and sinonasal anatomy in Asian patients with unilateral primary acquired nasolacrimal duct obstruction (PANDO) through computed tomography (CT).

METHODS

We enrolled 34 patients with unilateral PANDO who underwent endoscopic dacryocystorhinostomy, alongside 34 age- and sex-matched control patients without documented epiphora complaints. We compared BNLD and sinonasal parameters on CT images between the affected and unaffected sides of PANDO patients and the control group.

RESULTS

The entrance area of the BNLD was larger on the affected side of unilateral PANDO patients compared to both the unaffected side (p = 0.012) and the control group (p = 0.046). The open angle in the coronal plane was greater on both the affected (p = 0.044) and unaffected side (p = 0.028) than in the control group. Minimal area and distal area in the axial plane showed no differences among the 3 groups. Paranasal parameters did not differ between the study and control groups. More patients in the study group had superiorly located nasal septum deviation than the control group (p = 0.048). A trend suggested that more patients in the study group had anteriorly located nasal septum deviation than the control group (p = 0.056), although not reaching statistical significance.

CONCLUSION

The increased angular tilt in PANDO patients could impede fluid drainage from a fluidics standpoint. The larger BNLD area on the affected side reflects inflammation-induced osteolysis. Additionally, sinonasal variations, particularly nasal septum deviation at the anterior and superior half, have been identified as contributing to a higher risk of PANDO.

Association of endogenous sex hormone levels with tooth loss due to periodontitis in men and post-menopausal women: The multi-ethnic study of atherosclerosis

AIM

To investigate the association between endogenous sex hormone levels and history of tooth loss related to periodontitis in healthy middle-aged to older men and post-menopausal women.

METHODS

This cross-sectional study included 5649 participants aged 45-84 (mean age, 63 ± 10 years) from the Multi-Ethnic Study of Atherosclerosis cohort who had sex hormone levels measured and answered a questionnaire regarding perceived periodontal status at exam 1. Multivariable logistic regression was used to examine the association of sex hormones (exposure) with history of tooth loss (outcome), stratified by sex.

RESULTS

Among post-menopausal women, higher free testosterone (per 1SD) was associated with a greater prevalence of tooth loss [OR 1.49 (95% CI, 1.08-2.05)], whereas higher sex hormone binding globulin (SHBG) was associated with a lower prevalence of tooth loss [OR 0.74 (0.58-0.94)], after adjustment for cardiometabolic risk factors and reproductive factors. In men, higher free testosterone and lower SHBG were associated with a lower prevalent probability of tooth loss in unadjusted analysis, but these associations lost significance after covariate adjustment.

CONCLUSION

A higher androgenic sex hormone profile in post-menopausal women (i.e., increased free testosterone, lower SHBG) was associated with an increased prevalence of tooth loss, after adjusting cardiometabolic risk factors. No such association was found in men. These findings suggest that sex hormones may influence or serve as a marker for periodontal health.

Ozone therapy improves early stages of osseointegration in ovariectomized rats

OBJECTIVE

the aim of this study was to analyze the influence of ozone therapy (OZN) on peri-implant bone repair in critical bones by installing osseointegrated implants in the tibia of ovariectomized rats.

METHODOLOGY

ovariectomy was performed on 30 Wistar rats, aged six months (Rattus novergicus), and, after 90 days, osseointegrated implants were installed in each tibial metaphysis. The study groups were divided into the animals that received intraperitoneal ozone at a concentration of 700 mcg/kg - OZ Group (n=15) - and a control group that received an intraperitoneal saline solution and, for this reason, was named the SAL group (n=15). The applications for both groups occurred during the immediate post-operative period on the 2nd, 4th, 6th, 8th, 10th, and 12th day post-surgery. At various stages (14, 42, and 60 days), the animals were euthanized, and tests were performed on their tibiae. These tests include histomorphometric and immunohistochemical analyses, computerized microtomography, sampling in light-cured resin for calcified sections, and confocal microscopy. The obtained data were then analyzed using One-way ANOVA and the Shapiro-Wilk, Kruskal-Wallis, and student t-tests (P<0.05).

RESULTS

our findings indicate that the OZ group (3.26±0.20 mm) showed better cellular organization and bone neoformation at 14 days (SAL group, 0.90±1.42 mm) (P=0.001). Immunohistochemistry revealed that osteocalcin labeling was moderate in the OZ group and mild in the SAL group at 14 and 42 days post-surgery. The data from the analysis of calcified tissues (microtomography, histometric, and bone dynamism analysis) at 60 days showed no statistically significant differences between the groups (P=0.32).

CONCLUSION

it was concluded that ozone therapy anticipated the initial phases of the peri-implant bone repair process.

Hormone replacement therapy and periodontitis progression in postmenopausal women: A prospective cohort study

OBJECTIVE

This study aimed to investigate the responses of periodontal environment to hormone replacement therapy (HRT) in postmenopausal women with or without periodontitis.

BACKGROUND

HRT is a common and effective strategy for controlling menopausal symptoms, while the changes of periodontal environment under it, particularly in postmenopausal women with periodontitis, remain unclear.

METHODS

As a prospective cohort study, a total of 97 postmenopausal women receiving HRT were screened, including 47 with and 50 without periodontitis. Correspondingly, 97 women did not receiving HRT were screened as controls during the same period. The full-mouth sulcus bleeding index (SBI), bleeding on probing (BOP), probing pocket depth (PPD), and clinical attachment level (CAL) were measured using periodontal probes. The levels of interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α) in the gingival crevicular fluid were measured using enzyme-linked immunosorbent assay. In addition, cone beam computed tomography was performed to measure the alveolar bone height (ABH) and bone mineral density (BMD).

RESULTS

In postmenopausal women without periodontitis, no significantly changes on periodontal parameters were observed after HRT. In women with stage II periodontitis, SBI, BOP, IL-6, and TNF-α were significant decreased after one year and two years of HRT. Compared to the controls, women with stage II periodontitis who underwent HRT had significantly lower CAL and ABH and higher BMD in the second year. The incidence of at least one site with CAL increase ≥1 mm between baseline and 2 years was significantly lower in the HRT group than in the control group in women with stage II periodontitis. In addition, HRT was significantly associated with a decrease in SBI, BOP, IL-6, and TNF-α in the first year and with a decrease in CAL, SBI, BOP, IL-6, and ABH and an increase in BMD in the second year.

CONCLUSIONS

In postmenopausal women with stage II periodontitis, HRT is associated with the alleviation of inflammation within two years and the remission of alveolar bone loss in the second year. HRT appears to decrease the incidence of CAL increase ≥1 mm within 2 years in women with periodontitis by inhibiting inflammation and alveolar bone loss.

Decreased bone mineral density is associated with an increased number of teeth with periodontitis progression: a 5-year retrospective cohort study

OBJECTIVE

Longitudinal studies on the systemic bone loss-periodontitis relationship are limited with disparate results. The aim of this study was to investigate the association between bone mineral density (BMD) and periodontitis progression, controlling for other covariables in a Thai population.

MATERIALS AND METHODS

In 2,418 participants, BMD values of the lumbar spine, femoral neck, and total hip were measured with dual-energy X-ray absorptiometry at baseline. Each participant's BMD status was classified as normal, osteopenia, or osteoporosis. Full mouth periodontal examinations on 6 sites/tooth were performed at baseline and 5-year follow-up visits. Periodontitis progression was defined as a tooth presenting an additional proximal CAL loss of ≥ 3 mm or an additional lost tooth with a baseline CAL ≥ 5 mm. The risk effects of BMD status on the number of teeth with periodontitis progression were analyzed using multivariate Poisson regression.

RESULTS

Baseline BMD status of osteoporosis was associated with an increased number of teeth with periodontitis progression in the subgroups of postmenopausal women, non-smokers, and participants with periodontitis stage III/IV with adjusted risk ratios of 1.31 (95% CI = 1.09-1.58), 1.19 (95% CI = 1.04-1.36), and 1.13 (95% CI = 1.00-1.28), respectively.

CONCLUSION

Baseline BMD in the osteoporosis range increased the risk of having a greater number of teeth with periodontitis progression in specific participant subgroups.

CLINICAL RELEVANCE

Decreased BMD is a potential factor affecting periodontitis progression risk in some individuals. Multidisciplinary approaches in educating and maintaining patients' bone-oral health may help improve their quality of life.

Comparative evaluation of periodontal health status of pre and postmenopausal females

BACKGROUND

Menopause in females is a corporeal stage that gives rise to a number of adaptive changes both at systemic and oral levels, prototypically occurring in the late fourth or fifth decade of life. Though physiological aging affects the oral tissue, the hormonal changes due to menopause also act as a major contributing factor in deteriorating the health of oral tissues. Thus, the main aim of our study was to compare the overall periodontal status and alkaline phosphatase levels in the saliva of females in their pre and postmenopausal ages.

MATERIAL AND METHODS

This study was conducted on 200 female subjects coming to the Department of Periodontology at Rajendra Institute of Medical Science for oral prophylaxis. The subjects were arbitrarily selected in the age group ranging from 15 to 70 years and were further divided based on the inclusion criteria. Group A included 100 subjects with age ranging from 15 to 45 years, and group B, 100 subjects with age 54 to 70 years. Signs of periodontitis including clinical attachment loss, furcation involvement, and probing depth and salivary alkaline levels were obtained, evaluated, compared, and analyzed.

RESULTS

In group A 65% of patients had grade 0 and 28% had grade 1 of clinical attachment level. Similarly in group B, 44% of the total had grade 0 of clinical attachment loss, 38% had grade 1, and 18% were of grade 2. On evaluating grades of furcation involvement, around 45% of the total patients in group A were grade 1 (incipient, pocket formation), while in group B, 51% of the total patients were grade 1. At least 46% in group A and only 20% in group B had no signs of furcation involvement. Salivary alkaline phosphatase levels in pre and postmenopausal patients showed a significant difference between the two groups was obtained.

CONCLUSION

The study concluded a major difference in the periodontal health of pre and postmenopausal women with many influencing factors apart from menopause itself.

Inverse Correlation Between Bone Mineral Density and Systemic Immune Inflammation Index in Postmenopausal Turkish Women

AIM

In this study, the correlation between the change in bone mineral density (BMD) and the numerical value of the systemic immune inflammation index (SII) in postmenopausal Turkish women was investigated.

MATERIAL AND METHODS

The study comprised patients who had undergone menopause for at least one year and whose blood samples were examined by dual-energy X-ray absorptiometry (DEXA) on the same day. A retrospective evaluation of 527 postmenopausal women was performed. Age, body mass index (BMI), BMD, t score, neutrophil-lymphocyte-platelet-monocyte counts, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), monocyte-to-lymphocyte ratio (MLR), and SII (platelet count x neutrophil count/lymphocyte count) values were calculated and recorded.

RESULTS

When the data were analyzed with the Statistical Package for the Social Sciences (SPSS; IBM SPSS Statistics for Windows, version 26.0. Armonk, NY: IBM Corp.), neutrophil (p<0.001), lymphocyte (p=0.004), monocytes (p=0.002), platelet distribution width (PDW) (p=0.02), procalcitonin (PCT) (p=0.04), erythrocyte sedimentation rate (ESR) (p=0.001), C-reactive protein (CRP) (p=0.001), NLR (p=0.001), PLR (p=0.004), MLR (p=0.003), and SII (p=0.001) values were found to be higher in the postmenopausal osteoporosis (PMO) group than in the normal and osteopenia groups (p<0.05). When the platelet (p=0.15), mean platelet volume (MPV) (p=0.07), and 25-OH vitamin-D (p=0.15) values were compared, no correlation was found between the groups (normal, osteopenia, and PMO) (p>0.05).

CONCLUSION

This study revealed that NLR, PLR, MLR, and SII values were inversely correlated with the change in BMD in postmenopausal Turkish women. These biomarkers, which are obtained from a simple, affordable, and accessible routine blood examination, may play an effective role in the early diagnosis and prevention of PMO in the future.

Berberine regulates bone metabolism in apical periodontitis by remodelling the extracellular matrix

OBJECTIVES

The objectives of this study were to explore the role and related mechanism of berberine in repairing bone destruction in apical periodontics (AP).

MATERIALS AND METHODS

AP was established in 14 of 21 male Wistar rats (four weeks of age; 70-80 g) for 3 weeks. The canals were cleaned and administered berberine (2 mg/ml; n = 7) or calcium hydroxide (100 mg/ml; control; n = 7), followed by glass ionomer cement sealing. After 3 weeks, specimen collection followed by micro-computed tomography (μ-CT) and histological staining was performed, including haematoxylin and eosin staining, Masson's trichrome staining, tartrate-resistant acid phosphatase staining, immunohistochemistry and immunofluorescence histochemistry.

RESULTS

μ-CT showed that AP lesion volume reduced in the berberine group. Histopathology showed that berberine decreased the activity and number of osteoclasts but increased the expression of proteins related to osteoblast differentiation, including alkaline phosphatase and osterix. The immune cell, T cell, dendritic cell and macrophage counts were significantly decreased in the berberine group. In the berberine group, the expression of extracellular matrix-degraded proteases, metalloproteinases, was decreased; however, that of extracellular matrix-stable proteases, lysyl oxidases, was increased.

CONCLUSIONS

Berberine controlled the inflammatory response and regulated bone metabolism in AP by reducing metalloproteinase expression and increasing lysyl oxidases expression.

Macrophages and Bone Remodeling

Bone remodeling in the adult skeleton facilitates the removal and replacement of damaged and old bone to maintain bone quality. Tight coordination of bone resorption and bone formation during remodeling crucially maintains skeletal mass. Increasing evidence suggests that many cell types beyond osteoclasts and osteoblasts support bone remodeling, including macrophages and other myeloid lineage cells. Herein, we discuss the origin and functions for macrophages in the bone microenvironment, tissue resident macrophages, osteomacs, as well as newly identified osteomorphs that result from osteoclast fission. We also touch on the role of macrophages during inflammatory bone resorption. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Osteoimmune regulation underlies oral implant osseointegration and its perturbation

In the field of biomaterials, an endosseous implant is now recognized as an osteoimmunomodulatory but not bioinert biomaterial. Scientific advances in bone cell biology and in immunology have revealed a close relationship between the bone and immune systems resulting in a field of science called osteoimmunology. These discoveries have allowed for a novel interpretation of osseointegration as representing an osteoimmune reaction rather than a classic bone healing response, in which the activation state of macrophages ((M1-M2 polarization) appears to play a critical role. Through this viewpoint, the immune system is responsible for isolating the implant biomaterial foreign body by forming bone around the oral implant effectively shielding off the implant from the host bone system, i.e. osseointegration becomes a continuous and dynamic host defense reaction. At the same time, this has led to the proposal of a new model of osseointegration, the foreign body equilibrium (FBE). In addition, as an oral wound, the soft tissues are involved with all their innate immune characteristics. When implant integration is viewed as an osteoimmune reaction, this has implications for how marginal bone is regulated. For example, while bacteria are constitutive components of the soft tissue sulcus, if the inflammatory front and immune reaction is at some distance from the marginal bone, an equilibrium is established. If however, this inflammation approaches the marginal bone, an immune osteoclastic reaction occurs and marginal bone is removed. A number of clinical scenarios can be envisioned whereby the osteoimmune equilibrium is disturbed and marginal bone loss occurs, such as complications of aseptic nature and the synergistic activation of pro-inflammatory pathways (implant/wear debris, DAMPs, and PAMPs). Understanding that an implant is a foreign body and that the host reacts osteoimmunologically to shield off the implant allows for a distinction to be drawn between osteoimmunological conditions and peri-implant bone loss. This review will examine dental implant placement as an osteoimmune reaction and its implications for marginal bone loss.

Association between total body bone mineral density and periodontitis: A Mendelian randomization study

BACKGROUND

The purpose of the study was to examine the association between total body bone mineral density (BMD) and periodontitis using Mendelian randomization (MR) analysis.

METHODS AND MATERIALS

We used 81 single nucleotide polymorphisms (SNPs) associated with BMD at a p-value of < 5 × 10^-8 from a genome-wide association study (GWAS) of 66,628 individuals of European descent. The GWAS for periodontitis was derived from a meta-analysis of seven cohort studies that included 17,353 cases and 28,210 controls of European ancestry.

RESULTS

MR showed no association between BMD and periodontitis (odds ratio per standard deviation increment in genetically predicted BMD = 1.00; 95% confidence interval: 0.92-1.08). Leave-one-out analyses and pleiotropy-robust methods did not indicate any bias.

CONCLUSIONS

The MR study provided no evidence that BMD might be causally linked to periodontitis. Hence it may be concluded as the key finding that BMD depletion does not increase the risk of periodontitis.

Periapical status in patients affected by osteoporosis: A retrospective clinical study

Objectives

To assess the periapical status in patients with osteoporosis (OP) treated with denosumab (D), bisphosphonates (BPs), or not on medication, and to understand if these conditions influence the prevalence and the progression of apical periodontitis (AP).

Material and Methods

Seventy‐six patients with OP alone or treated with D, or BPs, formed the study group (O), and those from 76 patients matched for age and sex, without diseases, and not taking medications, constituted the control (C) in this retrospective case−control study. The data from the complete clinical and radiographic examination, medical history, decayed, missing, and filled teeth (DMFT), and periapical index score (PAI) were recorded for each patient. Wilcoxon rank test, χ², and Student's t test were used as appropriate.

Results

The prevalence of AP was similar in O and C. Furthermore, AP was significantly more frequent in root canal‐treated teeth in O patients (p = .03).

Conclusions

OP does not appear to be associated with the development of AP. Moreover, the increased prevalence of AP in root canal‐treated teeth in O patients highlights a possible relationship between the healing dynamics of the disease post‐therapy and the patients' medication. A larger sample is needed to confirm these findings.

Effects of periodontal and bisphosphonate treatment on the gingival crevicular levels of sclerostin and dickkopf-1 in postmenopausal osteoporosis with and without periodontitis

OBJECTIVE AND BACKGROUND

Both periodontitis and osteoporosis are associated with osteoclast-related bone resorption. Bone metabolism is regulated by wingless-type MMTV integration site family (WNT), and WNT/β-catenin signals are controlled by physiological antagonists including dickkopf-1 (DKK-1) and sclerostin (SOST). This study examined the effects of periodontal and bisphosphonate (BP) treatment on the gingival crevicular fluid (GCF) sclerostin (SOST) and dickkopf-related protein-1 (DKK-1) levels in osteoporotic and systemically healthy postmenopausal women with and without periodontitis.

MATERIALS AND METHODS

A total of 48 postmenopausal women were divided into 4 groups (n = 12) according to periodontal health and osteoporosis status, as follows: Group OP/P: subjects with both osteoporosis and periodontitis; Group P: systemically healthy subjects with periodontitis; Group OP: periodontally healthy subjects with osteoporosis; Group H: systemically and periodontally healthy controls. Clinical data and GCF SOST and DKK-1 levels of the participants were collected at baseline and at 6 and 12 months following the initiation of periodontal and/or BP treatment in the experimental groups. GCF SOST and DKK-1 data were obtained by ELISA.

RESULTS

Clinical improvements were observed in all experimental groups. GCF SOST and DKK1 baseline levels varied significantly between groups due to periodontal disease (p < .001). Following treatment, significant increases in SOST and DKK-1 concentrations and significant decreases in total amounts of SOST were observed in both periodontitis groups (OP/P, P). However, while total amounts of DKK-1 decreased in Group OP/P, in Group P, these amounts had significantly increased at 12 months post-treatment (p < .05). At both 6 and 12 months post-treatment, SOST and DDK1 total amounts in Groups OP/P, OP, and H were similar (p > .05), whereas significant differences were observed between Groups H and P, indicating a deviation from periodontal health in Group P (p < .01).

CONCLUSIONS

Significant changes in GCF SOST and DKK-1 levels were observed among women with osteoporosis who received both periodontal and BP treatment. A more detailed examination of how these treatment protocols can be combined may lead to new therapeutic approaches towards periodontal disease.

Quality of Life in Menopausal Women with Dental Restorations and Implants

Aim:

This multicenter study examined the relationship, possible interactions, and intermittent effects that dental implants and prostheses can have on menopausal women’s quality of life as well as provided information regarding the possible side effects of therapeutic regimens on menopause and osteoporosis or osteopenia.

Materials and Methods:

Questionnaires consisted of selected quality of life questions based on specific and additional medical and dental (mainly prosthodontic) questions, which were administered to 100 Greek menopausal/post-menopausal women (Age: Mean Value=63,62 years old) with osteopenia or with or without osteoporosis, with dental implants and implant restorations, or conventional prosthetic restorations visiting two University Hospitals. Menopausal/post-menopausal status was judged on the basis of either secondary, definitive amenorrhoea or based on follicular stimulation hormone ​​(FSH) values, estradiol, and clinical risk factors.

Results:

Participants had a statistically significantly better “functional” and “psychological” feeling after prosthodontic rehabilitation with and without implants. Three out of four reported that their dentist informed them of the possible implant problems that might arise from osteoporosis and its treatment (medications). Moreover, osteopenia was found to be associated with a very lower problem percentage. The bisphosphonate treatment had the highest rate (80%) of reported implant problems than non-bisphosphonate treatment (30%). The hormone replacement therapy (HRT) for menopause was reported to be more associated with problems in implant placement (19%) than in those without treatment (27.3%).

Conclusion:

The questionnaires revealed a significant improvement concerning women’s life quality and well-documented information about the problems their dental implants and restorations may cause in association with menopause and/or osteoporosis.

The Hippo Pathway Effectors YAP/TAZ Are Essential for Mineralized Tissue Homeostasis in the Alveolar Bone/Periodontal Complex

YAP and TAZ are essential transcriptional co-activators and downstream effectors of the Hippo pathway, regulating cell proliferation, organ growth, and tissue homeostasis. To ask how the Hippo pathway affects mineralized tissue homeostasis in a tissue that is highly reliant on a tight homeostatic control of mineralized deposition and resorption, we determined the effects of YAP/TAZ dysregulation on the periodontal tissues alveolar bone, root cementum, and periodontal ligament. Loss of YAP/TAZ was associated with a reduction of mineralized tissue density in cellular cementum and alveolar bone, a downregulation in collagen I, alkaline phosphatase, and RUNX2 gene expression, an increase in the resorption markers TRAP and cathepsin K, and elevated numbers of TRAP-stained osteoclasts. Cyclic strain applied to periodontal ligament cells resulted in YAP nuclear localization, an effect that was abolished after blocking YAP. The rescue of YAP signaling with the heparan sulfate proteoglycan agrin resulted in a return of the nuclear YAP signal. Illustrating the key role of YAP on mineralization gene expression, the YAP inhibition-related downregulation of mineralization-associated genes was reversed by the extracellular matrix YAP activator agrin. Application of the unopposed mouse molar model to transform the periodontal ligament into an unloaded state and facilitate the distal drift of teeth resulted in an overall increase in mineralization-associated gene expression, an effect that was 10–20% diminished in Wnt1Cre/YAP/TAZ mutant mice. The unloaded state of the unopposed molar model in Wnt1Cre/YAP/TAZ mutant mice also caused a significant three-fold increase in osteoclast numbers, a substantial increase in bone/cementum resorption, pronounced periodontal ligament hyalinization, and thickened periodontal fiber bundles. Together, these data demonstrated that YAP/TAZ signaling is essential for the microarchitectural integrity of the periodontium by regulating mineralization gene expression and preventing excessive resorption during bodily movement of the dentoalveolar complex.

Single-Cell Sequencing Unveils the Heterogeneity of Nonimmune Cells in Chronic Apical Periodontitis

Chronic apical periodontitis (CAP) is a unique dynamic interaction between microbial invasions and host defense mechanisms, resulting in infiltration of immune cells, bone absorption, and periapical granuloma formation. To help to understand periapical tissue pathophysiology, we constituted a single-cell atlas for 26,737 high-quality cells from inflammatory periapical tissue and uncovered the complex cellular landscape. The eight types of cells, including nonimmune cells and immune cells, were identified in the periapical tissue of CAP. Considering the key roles of nonimmune cells in CAP, we emphasized osteo-like cells, basal/stromal cells, endothelial cells, and epithelial cells, and discovered their diversity and heterogeneity. The temporal profiling of genomic alterations from common CAP to typical periapical granuloma provided predictions for transcription factors and biological processes. Our study presented potential clues that the shift of inflammatory cytokines, chemokines, proteases, and growth factors initiated polymorphic cell differentiation, lymphangiogenesis, and angiogenesis during CAP.

Single Cell RNA Sequencing Reveals Critical Functions of Mkx in Periodontal Ligament Homeostasis

The periodontal ligament (PDL) comprises a fibrous tissue that connects teeth to alveolar bone and is essential for periodontal function. The transcription factor mohawk homeobox (Mkx) is expressed in the PDL where it plays an important role in the development and maintenance of the PDL. However, the precise and critical functions of Mkx in the cell populations comprising PDL have not yet been elucidated. The present study aimed to clarify the effects of a Mkx deficiency on PDL cellular heterogeneity and differences between gene expression in PDL tissues from wild-type (WT) (Mkx^+/+) and Mkx knockout (Mkx^−/−) rats using single-cell RNA sequencing. We identified 12 cell clusters comprising mesenchymal cells and macrophages. The expression of Mkx and scleraxis (Scx; another key transcription factor of PDL), was mutually exclusive, and partitioned mesenchymal cell clusters into Mkx and Scx types that dominantly expressed proteoglycans and elastic fibers, and type 1 and 3 collagen, respectively. Ossification-related genes were upregulated in mesenchymal cell and osteoblast clusters with more Mkx^−/− than Mkx^+/+ PDLs. Increased number of cells and inflammatory mediators were observed in macrophage clusters of Mkx^−/− PDL. These results suggested that Mkx plays an important role in maintaining PDL homeostasis by regulating specific cell populations and gene expression.

Wound healing in periodontal disease induces macrophage polarization characterized by different arginine-metabolizing enzymes

BACKGROUND AND OBJECTIVE

Macrophages play important roles from the initiation of inflammation to wound healing. Two phenotypes of macrophages, namely pro-inflammatory type macrophages (M1-MΦ) and anti-inflammatory type macrophages (M2-MΦ), have been reported. Two contrasting metabolic enzymes that use arginine as a substrate, inducible nitric oxide synthase (iNOS), and arginase-1 (Arg-1), have been identified as M1-MΦ and M2-MΦ markers, respectively. The purpose of this study was to elucidate the temporal dynamics of the macrophage phenotype during the progression and healing phases of experimental periodontitis in mice.

MATERIAL AND METHODS

A total of 63 C57BL/6J mice were divided into the following 3 groups: control (C), periodontitis (P), and healing (H). To induce periodontitis, a silk ligature was placed around the maxillary bilateral second molars of mice in the periodontitis and healing groups. In the healing group, the ligature was removed 3 days after ligation to induce tissue healing. Maxillary tissue was collected on day 0 for the control group, days 1, 3, 5, and 7 for the periodontitis group (P1, P3, P5, and P7), and days 5 and 7 for the healing group (H5 and H7: 3 days with the ligation + 2 days or 4 days following ligature removal). The left side of the maxilla was subjected to bone structure analysis using micro-computed tomography and gene expression analysis using polymerase chain reaction. On the right side, immunohistochemistry was performed to histopathologically evaluate the localization of macrophages by phenotype in the periodontal tissue.

RESULTS

In the alveolar bone structure analysis, the linear distance of bone height increased significantly in the P5 and P7 groups, whereas bone volume fraction and bone mineral density decreased over time after ligature placement; in the healing group (H5 and H7), these parameters improved significantly compared with the periodontitis group (P5 and P7). Expression of genes encoding pro-inflammatory cytokines and iNOS increased in the periodontitis group, and expression of anti-inflammatory cytokine genes and Arg-1 increased in the healing group. Furthermore, the iNOS/Arg-1 expression ratio increased with ligation, whereas the ratio in the healing groups (H5 and H7) significantly decreased compared with the periodontitis groups (P5 and P7). Immunofluorescence staining revealed a significant increase in the number of iNOS-positive macrophages in the periodontitis group and decrease in the healing group. In contrast, the number of Arg-1-positive macrophages decreased in the periodontitis group and increased in the healing group.

CONCLUSION

The results of the present study suggest that wound healing in periodontal disease induces macrophage polarization from M1-MΦ to M2-MΦ characterized by iNOS and Arg-1.

Oral Osteomicrobiology: The Role of Oral Microbiota in Alveolar Bone Homeostasis

Osteomicrobiology is a new research field in which the aim is to explore the role of microbiota in bone homeostasis. The alveolar bone is that part of the maxilla and mandible that supports the teeth. It is now evident that naturally occurring alveolar bone loss is considerably stunted in germ-free mice compared with specific-pathogen-free mice. Recently, the roles of oral microbiota in modulating host defense systems and alveolar bone homeostasis have attracted increasing attention. Moreover, the mechanistic understanding of oral microbiota in mediating alveolar bone remodeling processes is undergoing rapid progress due to the advancement in technology. In this review, to provide insight into the role of oral microbiota in alveolar bone homeostasis, we introduced the term “oral osteomicrobiology.” We discussed regulation of alveolar bone development and bone loss by oral microbiota under physiological and pathological conditions. We also focused on the signaling pathways involved in oral osteomicrobiology and discussed the bridging role of osteoimmunity and influencing factors in this process. Finally, the critical techniques for osteomicrobiological investigations were introduced.

Leucine rich amelogenin peptide prevents ovariectomy-induced bone loss in mice

Amelogenins, major extra cellular matrix proteins of developing tooth enamel, are predominantly expressed by ameloblasts and play significant roles in the formation of enamel. Recently, amelogenin has been detected in various epithelial and mesenchymal tissues, implicating that it might have distinct functions in various tissues. We have previously reported that leucine rich amelogenin peptide (LRAP), one of the alternate splice forms of amelogenin, regulates receptor activator of NF-kappa B ligand (RANKL) expression in cementoblast/periodontal ligament cells, suggesting that the amelogenins, especially LRAP, might function as a signaling molecule in bone metabolism. The objective of this study was to identify and define LRAP functions in bone turnover. We engineered transgenic (TgLRAP) mice using a murine 2.3kb α1(I)-collagen promoter to drive expression of a transgene consisting of LRAP, an internal ribosome entry site (IRES) and enhanced green fluorescent protein (EGFP) to study functions of LRAP in bone formation and resorption. Calvarial cell cultures from the TgLRAP mice showed increased alkaline phosphatase (ALP) activity and increased formation of mineralized nodules compared to the cells derived from wild-type (WT) mice. The TgLRAP calvarial cells also showed an inhibitory effect on osteoclastogenesis in vitro. Gene expression comparison by quantitative polymerase chain reaction (Q-PCR) in calvarial cells indicated that bone formation makers such as Runx2, Alp, and osteocalcin were increased in TgLRAP compared to the WT cells. Meanwhile, Rankl expression was decreased in the TgLRAP cells in vitro. The ovariectomized (OVX) TgLRAP mice resisted bone loss induced by ovariectomy resulting in higher bone mineral density in comparison to OVX WT mice. The quantitative analysis of calcein intakes indicated that the ovariectomy resulted in increased bone formation in both WT and TgLRAP mice; OVX TgLRAP appeared to show the most remarkably increased bone formation. The parameters for bone resorption in tissue sections showed increased number of osteoclasts in OVX WT, but not in OVX TgLRAP over that of sham operated WT or TgLRAP mice, supporting the observed bone phenotypes in OVX mice. This is the first report identifying that LRAP, one of the amelogenin splice variants, affects bone turnover in vivo.

Genetic Impact on Bone Modulation-A Review Bridging Bioscience to Genetic Engineering

Genes control approximately 60% to 75% of the variance of peak bone mass/density and a much smaller amount of variance in rate of loss.

Bone mass increases during growth to a peak value and soon after begins to decline. Most of the genetic effect is exerted during growth and so influences peak bone mass; whether there is an additional genetic effect on the rate of bone loss is less clear. So, this article aims to place emphasis on various oral and systemic conditions that are manifested due to altered gene function. Genetic polymorphisms and mutations are simple, although the consequences of the mechanism are complex. The syndromic manifestation due to changes at genetic level will greatly affect the bone quality, which will ultimately affect any treatment prognosis. Hence, a better understanding of molecular mechanisms of bone remodeling helps to identify pathogenic causes of bone, skeletal diseases, and leads to the development of targeted therapies for these diseases. This review highlights notions on the connecting link between science and genetics as well as various oral scenarios where gene could bring about changes, resulting in deformities. There is an intense research awaited in the future which could intervene with the causes that bring about genetic modulations, so as to decrease the mortality rate of humans.

Noninflammatory Stress-Induced Remodeling of Mandibular Bone: Impact of Age and Pregnancy

PURPOSE

The impact of noninflammatory stress, such as aging and pregnancy, on human long bone remodeling is well-established, but little is known about the impact of these stressors on oral bones, including the mandibular bone. To begin to fill this gap in our knowledge, we utilized a mouse mandibular model to evaluate the impact of noninflammatory simple stressors, ie, aging and pregnancy, on bone mandibular architecture and bone density in the mandible using micro-CT.

MATERIALS AND METHODS

For the present study, mandibles were obtained from both aged and pregnant C57BL/6 mice and analyzed using micro-CT technology. Micro-CT metrics included bone volume fraction (BVF), total volume (TV), tissue density, and apparent density in the mandible on the mandibular area of compact and trabecular bone, in which the teeth are embedded. All bone-related metrics data from aged and pregnant mice were analyzed using ANOVA analysis and visualized in boxplots.

RESULTS

Age-dependent bone remodeling occurred over 4 to 18 weeks of age, ie, increases in BVF, TV, BV/TV, as well as tissue and bone density. Evaluation of bone remodeling in breeder mice (repeated pregnancy model) and virgin mice (age-matched controls) at 37 weeks of age demonstrated that breeder mice had a dramatic decline in all bone metrics measured.

CONCLUSIONS

This study underscores the need for more research on noninflammatory stress-related mandibular bone remodeling (eg, age and pregnancy), which compromises bone strength and tooth anchoring. The data also underscores loss of alveolar bone height, as in periodontitis, is an important metric for a more complete assessment of bone loss. This report on mice provides essential data that can be applied for oral-maxillofacial surgeons and periodontists when planning for dental implants in patients with such stressors. Periodontitis related bone loss occurs independent of skeletal homeostasis, although osteoporosis may adversely affect alveolar bone height in humans.

Outlining cell interaction and inflammatory cytokines on UV-photofunctionalized mixed-phase TiO2 thin film

Photofunctionalization mediated by ultraviolet (UV) light seems to be a promising approach to improve the physico-chemical characteristics and the biological response of titanium (Ti) dental implants. Seeing that photofunctionalization is able to remove carbon from the surface, besides to promote reactions on the titanium dioxide (TiO₂) layer, coating the Ti with a stable TiO₂ film could potentialize the UV effect. Thus, here we determined the impact of UV-photofunctionalized mixed-phase (anatase and rutile) TiO₂ films on the physico-chemical properties of Ti substrate and cell biology. Mixed-phase TiO₂ films were grown by radiofrequency magnetron sputtering on commercially pure titanium (cpTi) discs, and samples were divided as follow: cpTi (negative control), TiO₂ (positive control), cpTi UV, TiO₂ UV (experimental). Photofunctionalization was performed using UVA (360 nm - 40 W) and UVC (250 nm - 40 W) lamps for 48 h. Surfaces were analyzed in terms of morphology, topography, chemical composition, crystalline phase, wettability and surface free energy. Pre-osteoblastic cells (MC3T3E1) were used to assess cell morphology and adhesion, metabolism, mineralization potential and cytokine secretion (IFN-γ, TNF-α, IL-4, IL-6 and IL-17). TiO₂-coated surfaces exhibited granular surface morphology and greater roughness. Photofunctionalization increased wettability (p < 0.05) and surface free energy (p < 0.001) on both surface conditions. TiO₂-treated groups featured normal cell morphology and spreading, and greater cellular metabolic activity at 2 and 4 days (p < 0.05), whereas UV-photofunctionalized surfaces enhanced cell metabolism, cell adhered area, and calcium deposition (day 14) (p < 0.05). In general, assessed proteins were found slightly affected by either UV or TiO₂ treatments. Altogether, our findings suggest that UV-photofunctionalized TiO₂ surface has the potential to improve pre-osteoblastic cell differentiation and the ability of cells to form mineral nodules by modifying Ti physico-chemical properties towards a more stable context. UV-modified surfaces modulate the secretion of key inflammatory markers.

Design of synthetic microenvironments to promote the maturation of human pluripotent stem cell derived cardiomyocytes

Cardiomyocyte like cells derived from human pluripotent stem cells (hPSC-CMs) have a good application perspective in many fields such as disease modeling, drug screening and clinical treatment. However, these are severely hampered by the fact that hPSC-CMs are immature compared to adult human cardiomyocytes. Therefore, many approaches such as genetic manipulation, biochemical factors supplement, mechanical stress, electrical stimulation and three-dimensional culture have been developed to promote the maturation of hPSC-CMs. Recently, establishing in vitro synthetic artificial microenvironments based on the in vivo development program of cardiomyocytes has achieved much attention due to their inherent properties such as stiffness, plasticity, nanotopography and chemical functionality. In this review, the achievements and deficiency of reported synthetic microenvironments that mainly discussed comprehensive biological, chemical, and physical factors, as well as three-dimensional culture were mainly discussed, which have significance to improve the microenvironment design and accelerate the maturation of hPSC-CMs.

Associations between osteoporosis and risk of periodontitis: A pooled analysis of observational studies

Background

Periodontitis and osteoporosis are most popular among aging population and both conditions might be linked, even though, this suggestion still until now debated.

Objectives

A meta‐analysis on previous investigations has been used to evaluate the correlation between periodontitis and osteoporosis to determine whether osteoporosis is a local indicator of bone loss, or whether it is depending on or related to periodontitis causes.

Methods

The literature database, including but not excluding, The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, CINAHL, and Science Citation Index Expanded, was searched in this work during Feb, 2020. We conducted the investigations contain cohort studies, cross‐sectional studies, as well as case–control studies with relative risk (RR) or odds ratio (OR) and 95% confidence intervals (CIs). Subgroup and Sensitivity analysis were also applied to identify heterogeneity sources.

Results

23 observational studies with 12 cohorts, 7 cross‐sectional and 4 case–control studies, were included, together with 2,157,037 participants. Osteoporosis patients were more exposed to periodontitis (OR, 1.96; 95% CI, 1.50–2.54). Subgroup analyses showed that the higher risk of osteoporosis in periodontitis patients exists in both cross‐sectional studies (OR, 2.17; 95% CI, 1.80–2.61) and case–control studies (OR 2.63; 95% CI, 1.69–4.09), and marginally in cohort studies (OR, 1.70; 95% CI, 1.16–2.49).

Conclusion

Review analyses have shown that osteoporosis is closely related to the increased risk of periodontitis in the future. Dental specialists better to understand the potential association between periodontitis and osteoporosis.

Cytokines and Chemokines in Periodontitis

Periodontitis is a common inflammatory periodontal disease affecting a wide range of population all over the world. The causing bacteria releases chemicals which activate the innate immune system to release proinflammatory cytokines contributing to more progression. This activates the acquired immune system leading to more progression of periodontitis. As the immune response goes on, released cytokines and chemokines can damage the periodontal ligaments, gingiva, and alveolar bone. There are many types of cytokines and chemokines in periodontitis. Cytokines are peptide mediators who are responsible for cell signaling and communication. Chemokines are a large subfamily of cytokines having the ability to coordinate leukocyte recruitment and activation. This paper is a narrative review of the literature.This review ensures that inflammatory mediators in the case of periodontitis can cause a noticeable damage in the whole apparatus of the periodontium. It causes soft tissue inflammation and bone damage affected by the mediators of both innate and acquired immune system.The inflammatory process is accompanied by large network of cytokines and chemokines. There is high expression of proinflammatory cytokines such as interleukin (IL)-1α, IL-1β, IL-6, IL-12, tumor necrosis factor (TNF)-α, and regulatory cytokines such as IL-4, IL-1(RA) receptor antagonist, IL-10, and induced protein (IP)-10. There is also increased production of cytokines IL-10, IL-12, interferon-γ, IP-10, IL-1RA, and IL-4. Cytokines IL-17, IL-6, IL-1β, TNF-α, macrophage colony-stimulating factor, and prostaglandin E ₂ trigger the osteoclast activity causing bone resorption.

The effect of lipoxin A4 on E. coli LPS-induced osteoclastogenesis

Objectives

The objective of the present study was to investigate the effect of lipoxin-type A4 (LXA4) on bacterial-induced osteoclastogenesis.

Material and methods

Human periodontal ligament cells (PDLCs) in coculture with osteoclast precursors (RAW264.7 cells) were exposed to bacterial stimulation with lipopolysaccharide (LPS) to induce inflammation. After 24 h, cells were treated to 100 ng/ml of LXA4 and 50 ng/ml of forymul peptide receptor 2 (FPR2/ALX) receptor antagonist (Boc-2). After 5 days, osteoclastic resorptive activity was assessed on calcium phosphate (CaP) synthetic bone substitute. Additionally, osteoclastic differentiation was evaluated using tartrate-resistant acid phosphatase (TRAP) staining, TRAP enzymatic activity assay, and on the expression of osteoclast-specific genes.

Results

We found that stimulation of in the osteoclasts with LPS-stimulated PDLCs induced a significant increase in tartrate-resistant acid phosphatase (TRAP) positive cells, higher resorptive activity, and enhanced expression of specific genes. Meanwhile, LXA4-treatment exhibited strong anti-inflammatory activity, and was able to reverse these inflammatory effects.

Conclusions

We conclude that (1) PDLCs are a potential target for treating bacterial-induced bone resorption in patients with periodontal disease, and (2) LXA4 is a suitable candidate for such therapy.

Clinical relevance

The results prove that lipoxins have a protective role in bacterial-induced periodontal inflammation and alveolar bone resorption, which can be translated into a clinical beneficial alterative treatment.

Dilemma of Gonial Angle in Sex Determination: Sexually Dimorphic or Not?

BACKGROUND AND AIM

The determination of sex from human remains has a crucial role in forensic anthropology. It has been known that the mandible has several useful traits for sex determination. The gonial angle, which is one of them, has been evaluated by forensic practitioners to identify sexual dimorphism with morphologic and metrical analyses. However, there are opposing approaches on the sexual dimorphism of the gonial angle in the literature, which contradict each other. There are also some other studies asserting that it cannot be employed in sex determination. The purpose of this study is first to figure out the reason for this dilemma and then establish the significance of the gonial angle in sex determination in a white sample.

METHODS

Computed tomography scans were obtained from 300 adults (150 males and 150 females), which were divided into 3 age groups (20-39, 40-59, 60-80 years). The gonial angle, which is formed by 2 lines: (1) between the most posterior point of the mandibular condyle and the gonion and (2) between the most inferior point of the mandibular symphysis and gonion, was measured on computed tomography scans. In order to observe differences among the 3 age groups, the collected data were analyzed using 1-way analysis of variance followed by a least significant difference post hoc test. Two-way analysis of variance was used to compare sex differences in each age group.

DISCUSSION

It is suggested that the probable reason of this dilemma is the unsubtle samples of the researches. Categorizing the sample into age groups with statistically sufficient number makes the data more valuable in terms of examining the differences related to sexual dimorphism. This study also reported that males showed slightly smaller gonial angle values than those of females in all age groups. No statistically significant difference was observed in the gonial anthropometric values for middle age groups (20-39 and 40-59 years), whereas it shows statistically sexual dimorphism for senior adult group (60-80 years). However, the results revealed that the gonial angle is not a particularly good indicator to identify the sex from the cranium and should not be used as a sole criterion.

TNF-α is responsible for the contribution of stromal cells to osteoclast and odontoclast formation during orthodontic tooth movement

Compressive force during orthodontic tooth movement induces osteoclast formation in vivo. TNF-α plays an important role in mouse osteoclast formation and bone resorption induced by compressive force during orthodontic tooth movement. Stromal cells, macrophages and T cells take part in TNF-α-induced osteoclast formation in vitro. Root resorption caused by odontoclasts is a major clinical problem during orthodontic tooth movement. In this study, we determined the cell type targeted by TNF-α during compressive-force-induced osteoclast and odontoclast formation to elucidate the mechanism of bone and root resorption in vivo. An orthodontic tooth movement mouse model was prepared with a nickel-titanium closed coil spring inserted between the maxillary incisors and the first molar. Using TNF receptor 1- and 2-deficient (KO) mice, we found that osteoclast and odontoclast formation was mediated by TNF-α in orthodontic tooth movement. We generated four types of chimeric mice: wild-type (WT) bone marrow cells transplanted into lethally irradiated WT mice (WT>WT), KO bone marrow cells transplanted into lethally irradiated WT mice (KO>WT), WT bone marrow cells transplanted into lethally irradiated KO mice (WT>KO), and KO marrow cells transplanted into lethally irradiated KO mice (KO>KO). Using anti-CD4 and anti-CD8 antibodies, T cells were eliminated from these mice. We subjected these chimeric mice to orthodontic tooth movement. Orthodontic tooth movement was evaluated and tartrate-resistant acid phosphatase-positive cells along the alveolar bone (osteoclasts) and along the tooth root (odontoclasts) were counted after 12 days of tooth movement. The amount of orthodontic tooth movement, and the number of osteoclasts and odontoclasts on the compression side were significantly lower in WT>KO and KO>KO mice than in WT>WT and KO>WT mice. According to these results, we concluded that TNF-α-responsive stromal cells are important for osteoclast and odontoclast formation during orthodontic tooth movement.

TREM-1 Is Upregulated in Experimental Periodontitis, and Its Blockade Inhibits IL-17A and RANKL Expression and Suppresses Bone loss

Aim: Triggering receptor expressed on myeloid cells-1 (TREM-1) is a modifier of local and systemic inflammation. There is clinical evidence implicating TREM-1 in the pathogenesis of periodontitis. However, a cause-and-effect relationship has yet to be demonstrated, as is the underlying mechanism. The aim of this study was to elucidate the role of TREM-1 using the murine ligature-induced periodontitis model. Methods: A synthetic antagonistic LP17 peptide or sham control was microinjected locally into the palatal gingiva of the ligated molar teeth. Results: Mice treated with the LP17 inhibitor developed significantly less bone loss as compared to sham-treated mice, although there were no differences in total bacterial load on the ligatures. To elucidate the impact of LP17 on the host response, we analyzed the expression of a number of immune-modulating genes. The LP17 peptide altered the expression of 27/92 genes ≥ two-fold, but only interleukin (IL)-17A was significantly downregulated (4.9-fold). Importantly, LP17 also significantly downregulated the receptor activator of nuclear factor kappa-B-ligand (RANKL) to osteoprotegerin (OPG) ratio that drives osteoclastic bone resorption in periodontitis. Conclusion: Our findings show for the first time that TREM-1 regulates the IL-17A-RANKL/OPG axis and bone loss in experimental periodontitis, and its therapeutic blockade may pave the way to a novel treatment for human periodontitis.

A dual-action chitosan-based nanogel system of triclosan and flurbiprofen for localised treatment of periodontitis

This study aimed to develop a dual action, namely anti-inflammatory and antimicrobial, nanogels (NG) for the treatment of periodontitis using triclosan (TCS) and flurbiprofen (FLB). Triclosan, an antimicrobial drug, was prepared as nanoparticles (NPs) using poly-ε-caprolactone (PCL), while flurbiprofen, an anti-inflammatory drug, was directly loaded in a chitosan (CS) based hydrogel. The entwinement of both NPs and hydrogel loaded systems resulted in the NG. The characterisation data confirmed that the developed formulation consists of nanosized spherical structures and displays pH-dependent swelling/erosion and temperature-responsiveness. Besides, the NG exhibited adequate bioadhesiveness using the chicken pouch model and displayed antibacterial activity through the agar plate method. An in-vivo study of the NG on experimental periodontitis (EP) rats confirmed the dual antibacterial and anti-inflammatory effects which revealed an excellent therapeutic outcome. In conclusion, a dual action NG was successfully developed and proved to have superior therapeutic effects in comparison to physical mixtures of the individual drugs.

Developing a periodontal disease antibody array for the prediction of severe periodontal disease using machine learning classifiers

BACKGROUND

The aim of this study was to simultaneously and quantitatively assess the expression levels of 20 periodontal disease-related proteins in gingival crevicular fluid (GCF) from normal controls (NOR) and severe periodontitis (SP) patients with an antibody array.

METHODS

Antibodies against 20 periodontal disease-related proteins were spotted onto a glass slide to create a periodontal disease antibody array (PDD). The array was then incubated with GCF samples collected from 25 NOR and 25 SP patients. Differentially expressed proteins between NOR and SP patients were then used to build receiver operator characteristic (ROC) curves and compare five classification models, including support vector machine, random forest, k nearest neighbor, linear discriminant analysis, and Classification and Regression Trees.

RESULTS

Seven proteins (C-reactive protein, interleukin [IL]-1α, interleukin-1β, interleukin-8, matrix metalloproteinase-13, osteoprotegerin, and osteoactivin) were significantly upregulated in SP patients compared with NOR, while receptor activator of nuclear factor-kappa was significantly downregulated. The highest diagnostic accuracy using a ROC curve was observed for IL-1β with an area under the curve of 0.984. Five of the proteins (IL-1β, IL-8, MMP-13, osteoprotegerin, and osteoactivin) were identified as important features for classification. Linear discriminant analysis had the highest classification accuracy across the five classification models that were tested.

CONCLUSION

This study highlights the potential of antibody arrays to diagnose periodontal disease.

Systemic immune-inflammation index acts as a novel diagnostic biomarker for postmenopausal osteoporosis and could predict the risk of osteoporotic fracture

Background

Postmenopausal osteoporosis (PMOP) is a bone metabolism disorder involving systematic inflammation activation. Blood routine examination is easily available in clinical practice and contains abundant information reflecting the systematic inflammation level. Thus, it is attractive to achieve early diagnosis of PMOP and predict osteoporotic fracture risk just based on the biomarkers in blood routine examination.

Methods

A multi‐centric prospective cohort study was designed and enrolled postmenopausal women from two independent institutions. All participants underwent the dual‐energy X‐ray absorptiometry (DEXA) scanning for diagnosing PMOP. Blood routine examination was conducted, and the key inflammatory biomarkers such as neutrophil‐to‐lymphocyte ratio (NLR) and systemic immune‐inflammation index (SII) were calculated. PMOP patients were followed up to observe osteoporotic fracture and identify the related risk predictors.

Results

A total of 92 participants out of 238 enrolled postmenopausal women were diagnosed with PMOP, with a prevalence of 38.66%. The main risk factors identified for PMOP included older age (OR = 2.06, 95% CI = 1.14‐3.72), longer menopause duration (OR = 3.14, 95% CI = 2.06‐4.79), higher NLR (OR = 2.11, 95% CI = 1.37‐3.25), and higher SII (OR = 3.02, 95% CI = 1.98‐4.61). Besides age and menopause duration, SII ≥834.89 was newly identified as a prominent risk factor for discriminating osteoporotic fracture risk in PMOP patients (HR = 3.66, 95% CI = 1.249‐10.71).

Conclusion

As an easy and economical biomarker calculated from blood routine examination, SII not only acts as a good risk predictor for PMOP diagnosis but also well discriminates the osteoporotic fracture risk, which deserves further investigation and application in clinical practice.

Immune Function and Diversity of Osteoclasts in Normal and Pathological Conditions

Osteoclasts (OCLs) are key players in controlling bone remodeling. Modifications in their differentiation or bone resorbing activity are associated with a number of pathologies ranging from osteopetrosis to osteoporosis, chronic inflammation and cancer, that are all characterized by immunological alterations. Therefore, the 2000s were marked by the emergence of osteoimmunology and by a growing number of studies focused on the control of OCL differentiation and function by the immune system. At the same time, it was discovered that OCLs are much more than bone resorbing cells. As monocytic lineage-derived cells, they belong to a family of cells that displays a wide heterogeneity and plasticity and that is involved in phagocytosis and innate immune responses. However, while OCLs have been extensively studied for their bone resorption capacity, their implication as immune cells was neglected for a long time. In recent years, new evidence pointed out that OCLs play important roles in the modulation of immune responses toward immune suppression or inflammation. They unlocked their capacity to modulate T cell activation, to efficiently process and present antigens as well as their ability to activate T cell responses in an antigen-dependent manner. Moreover, similar to other monocytic lineage cells such as macrophages, monocytes and dendritic cells, OCLs display a phenotypic and functional plasticity participating to their anti-inflammatory or pro-inflammatory effect depending on their cell origin and environment. This review will address this novel vision of the OCL, not only as a phagocyte specialized in bone resorption, but also as innate immune cell participating in the control of immune responses.

Gingival Crevicular Fluid Levels of RANKL and OPG After Placement of Collagen Membrane With Simvastatin in the Treatment of Intrabony Defects in Chronic Periodontitis

Purpose:

The aim of this study was to estimate the Receptor activator of nuclear factor kappa-B ligand (RANKL) and Osteoprotegrin (OPG) levels in gingival crevicular fluid (GCF) after placement of collagen membrane with simvastatin in intrabony defects.

Materials and Methods:

Sixty subjects were grouped according to the treatment plan as Group I and Group II. Group I included patients with intrabony defects treated with collagen membrane. Group II included patients with intrabony defects treated with simvastatin of 1.5 mg concentration incorporated into the collagen membrane. A split-mouth design was planned, in which two contralateral sites with >5 mm probing pocket depth and radiographic evidence of bone loss at baseline were chosen. Probing pocket depth was standardized with acrylic stent in all the selected areas. GCF samples were collected at baseline and 21 days. The amount of RANKL and OPG in the samples was determined by commercial ELISA kits (Biomedica Medizinprodukte, Austria).

Results:

When comparing both the groups, Group II had more statistically significant (P < 0.001**) decrease in the levels of RANKL than Group I. In contrast to RANKL, the OPG levels were significantly increased in patients (Group II) having intrabony defects treated with collagen membrane along with simvastatin.

Conclusion:

Simvastatin-loaded collagen membrane expressed increased OPG and decreased RANKL levels, which could have a potential role in periodontal regeneration.

Production of Soluble Receptor Activator of Nuclear Factor Kappa-Β Ligand and Osteoprotegerin by Apical Periodontitis Cells in Culture and Their Modulation by Cytokines

RANKL, a bone-destructive cytokine, and OPG, its osteoprotective counterpart, are expressed in periapical lesions (PLs), which represent hystopatological manifestations of apical periodontitis. However, their regulation in PLs has not been elucidated yet. Therefore, our aim was to study the production of RANKL and OPG and their modulation by pro- and anti-inflammatory cytokines in PL cell cultures. Isolated PL cells were cultured alone or with addition of TNF-α, IFN-ϒ, IL-17, IL-4, IL-10, and IL- 33, respectively. The levels of RANKL and OPG in supernatants were measured by ELISA. The proportion of CD3⁺ (T cells) and CD19+/CD138+ (B cells/plasma cells) within isolated PLs was determined by immunocytochemistry. The levels of RANKL were higher in cultures of symptomatic PLs compared to asymptomatic PLs and PLs with the dominance of T cells (T-type lesions) over B cells/plasma cells (B-type lesions). A higher proportion of osteodestructive processes (RANKL/OPG ratio > 1.0) were detected in symptomatic PLs. The production of RANKL was upregulated by IFN-ϒ and IL-17 and higher concentrations of IL-33. IL-10 and lower concentrations of IL-33 augmented the production of OPG. The addition of either RANKL or anti-RANKL antibody to the cultures did not modify significantly the production of OPG. In conclusion, this original PL cell culture model suggests that increased bone destruction through upregulated production of RANKL could be associated with exacerbation of inflammation in PLs with the predominance of Th1 and Th17 responses and increased secretion of IL-33. In contrast, IL-10 and lower levels of IL-33, through upregulation of OPG, may suppress osteolytic processes.

Macrophage immunomodulation in chronic osteolytic diseases-the case of periodontitis

Periodontitis (PD) is a chronic osteolytic disease that shares pathogenic inflammatory features with other conditions associated with nonresolving inflammation. A hallmark of PD is inflammation-mediated alveolar bone loss. Myeloid cells, in particular polymorphonuclear neutrophils (PMN) and macrophages (Mac), are essential players in PD by control of gingival biofilm pathogenicity, activation of adaptive immunity, as well as nonresolving inflammation and collateral tissue damage. Despite mounting evidence of significant innate immune implications to PD progression and healing after therapy, myeloid cell markers and targets for immune modulation have not been validated for clinical use. The remarkable plasticity of monocytes/Mac in response to local activation factors enables these cells to play central roles in inflammation and restoration of tissue homeostasis and provides opportunities for biomarker and therapeutic target discovery for management of chronic inflammatory conditions, including osteolytic diseases such as PD and arthritis. Along a wide spectrum of activation states ranging from proinflammatory to pro-resolving, Macs respond to environmental changes in a site-specific manner in virtually all tissues. This review summarizes the existing evidence on Mac immunomodulation therapies for osteolytic diseases in the broader context of conditions associated with nonresolving inflammation, and discusses osteoimmune implications of Macs in PD.

Antiresorptive Agents are More Effective in Preventing Titanium Particle-Induced Calvarial Osteolysis in Ovariectomized Mice Than Anabolic Agents in Short-Term Administration

Aseptic loosening due to wear particle‐induced osteolysis is the main cause of arthroplasty failure and the influence of postmenopausal osteoporosis and anti‐osteoporosis treatment on Titanium (Ti) particle‐induced osteolysis remains unclear. 66 C57BL/6J female mice were used in this study. Ovariectomy (OVX) was performed to induce osteopenia mice and confirmed by micro‐CT. The Ti particle‐induced mouse calvaria osteolysis model was established subsequently and both OVX and Sham‐OVX mice were divided into four groups, respectively: Ti (‐) group, Ti group, Ti + zoledronic acid (ZOL) group (50ug/kg, local administration, single dose) and Ti + teriparatide (TPTD) group (40ug/kg/d, subcutaneous injection*14d). Mice calvarias were collected for micro‐CT and histomorphometric analysis 2 weeks after particle induction. 8 weeks after bilateral OVX, significantly reduced BMD and microstructure parameters in both proximal tibia and calvaria were observed in OVX mice when comparing with Sham‐OVX mice. OVX mice in Ti group had not only markly decreased BMD and BV/TV, but also significantly increased total porosity, eroded surface area and osteoclast numbers when comparing with Sham‐OVX mice. Shown by Two‐way ANOVA analysis, the interaction terms between OVX and Ti implantation on micro‐CT and histomorphometry parameters didn’t reach significant difference. As illustrated by micro‐CT and histological analysis, ZOL treatment markedly inhibited Ti particle‐induced osteolysis in OVX mice and Sham‐OVX mice, and there were significant differences when comparing to both Ti and Ti+TPTD group. The combination of osteoporosis and Ti particle implantation result in aggravated bone resorption, accompanied with increased osteoclasts and excessive inflammation response. ZOL was more effective in preventing Ti particle‐induced osteolysis in both OVX mice and Sham‐OVX mice than TPTD in short‐term administration. ZOL exert the protective effects on Ti particle‐induced bone loss via the suppression of osteoclasts.

Positive Association between Dietary Inflammatory Index and the Risk of Osteoporosis: Results from the KoGES_Health Examinee (HEXA) Cohort Study

Previous studies have found that diet’s inflammatory potential is related to various diseases. However, little is known about its relationship with osteoporosis. The aim of this study was to investigate the association between the dietary inflammatory index (DII^®) and osteoporosis risk in a large-scale prospective cohort study in Korea. This prospective cohort study included 159,846 participants (men 57,740; women 102,106) from South Korea with a mean follow-up of 7.9 years. The DII was calculated through a validated semi-quantitative FFQ (SQFFQ), and information on osteoporosis was self-reported by the participants. Analyses were performed by using a multivariable Cox proportional hazard model. Higher DII scores were associated with higher osteoporosis risk (HR 1.33; 95% CI 1.12–1.58). In women, a higher DII score indicated a higher risk of osteoporosis (HR 1.33; 95% CI 1.11–1.59). However, a hazards ratio of similar magnitude in men was not significant (HR 1.32; 95% CI 0.64–2.71). Post-menopausal women had higher risks of osteoporosis for higher DII scores (HR 1.33; 95% CI 1.09–1.63), whereas among pre-menopausal women, the relationship was not statistically significant (HR 1.39; 95% CI 0.87–2.21). Also, there was an increase in osteoporosis risk when the DII increased among women participants with irregular physical activity (HR 1.53; 95% CI 1.17–2.01); however, there was no statistically significant increase in osteoporosis risk among women participants with regular physical activity (HR 1.19; 95% CI 0.93–1.52). A more pro-inflammatory diet was significantly associated with higher osteoporosis risk in women. Given the similar magnitude of the hazards ratio, studies with sufficient numbers of men are warranted.