Cationic Glucan Dendrimer Gel-Mediated Local Delivery of Anti-OC-STAMP-siRNA for Treatment of Pathogenic Bone Resorption

Osteoclast stimulatory transmembrane protein (OC-STAMP) plays a pivotal role in the promotion of cell fusion during osteoclast differentiation (osteoclastogenesis) in the context of pathogenic bone resorption. Thus, it is plausible that the suppression of OC-STAMP through a bioengineering approach could lead to the development of an effective treatment for inflammatory bone resorptive diseases with minimum side effects. Here, we synthesized two types of spermine-bearing (Spe) cationic glucan dendrimer (GD) gels (with or without C12) as carriers of short interfering RNA (siRNA) to silence OC-STAMP. The results showed that amphiphilic C12-GD-Spe gel was more efficient in silencing OC-STAMP than GD-Spe gel and that the mixture of anti-OC-STAMP siRNA/C12-GD-Spe significantly downregulated RANKL-induced osteoclastogenesis. Also, local injection of anti-OC-STAMP-siRNA/C12-GD-Spe could attenuate bone resorption induced in a mouse model of periodontitis. These results suggest that OC-STAMP is a promising target for the development of a novel bone regenerative therapy and that C12-GD-Spe gel provides a new nanocarrier platform of gene therapies for osteolytic disease.

Shared genetic architecture between periodontal disease and type 2 diabetes: a large scale genome-wide cross-trait analysis

PURPOSE

To investigate the relationship between abnormal glucose metabolism, type 2 diabetes (T2D), and periodontal disease (PER) independent of Body Mass Index (BMI), we employed a genome-wide cross-trait approach to clarify the association.

METHODS

Our study utilized the most extensive genome-wide association studies conducted for populations of European ancestry, including PER, T2D, fasting glucose, fasting insulin, 2-hour glucose after an oral glucose challenge, HOMA-β, HOMA-IR (unadjusted or adjusted for BMI) and HbA1c.

RESULTS

With this approach, we were able to identify pleiotropic loci, establish expression-trait associations, and quantify global and local genetic correlations. There was a significant positive global genetic correlation between T2D (rg = 0.261, p = 2.65 × 10-13), HbA1c (rg = 0.182, p = 4.14 × 10-6) and PER, as well as for T2D independent of BMI (rg = 0.158, p = 2.34 × 10-6). A significant local genetic correlation was also observed between PER and glycemic traits or T2D. We also identified 62 independent pleiotropic loci that impact both PER and glycemic traits, including T2D. Nine significant pathways were identified between the shared genes between T2D, glycemic traits and PER. Genetically liability of HOMA-βadjBMI was causally associated with the risk of PER.

CONCLUSION

Our research has revealed a genetic link between T2D, glycemic traits, and PER that is influenced by biological pleiotropy. Notably, some of these links are not related to BMI. Our research highlights an underlying link between patients with T2D and PER, regardless of their BMI.

Triptolide mitigates the inhibition of osteogenesis induced by TNF-α in human periodontal ligament stem cells via the p-IκBα/NF-κB signaling pathway: an in-vitro study

BACKGROUND

Triptolide is a widely utilized natural anti-inflammatory drug in clinical practice. Aim of this study was to evaluate effects of triptolide on hPDLSCs osteogenesis in an inflammatory setting and to investigate underlying mechanisms.

METHODS

Using the tissue block method to obtain hPDLSCs from extracted premolar or third molar. Flow cytometry, osteogenic and adipogenic induction were carried out in order to characterise the features of the cells acquired. hPDLSC proliferative activity was assessed by CCK-8 assay to determine the effect of TNF-α and/or triptolide. The impact of triptolide on the osteogenic differentiation of hPDLSCs was investigated by ALP staining and quantification. Osteogenesis-associated genes and proteins expression level were assessed through PCR and Western blotting assay. Finally, BAY-117,082 was used to study the NF-κB pathway.

RESULTS

In the group treated with TNF-α, there was an elevation in inflammation levels while osteogenic ability and the expression of both osteogenesis-associated genes and proteins decreased. In the group co-treated with TNF-α and triptolide, inflammation levels were reduced and osteogenic ability as well as the expression of both osteogenesis-associated genes and proteins were enhanced. At the end of the experiment, both triptolide and BAY-117,082 exerted similar inhibitory effects on the NF-κB pathway.

CONCLUSION

The osteogenic inhibition of hPDLSCs by TNF-α can be alleviated through triptolide, with the involvement of the p-IκBα/NF-κB pathway in this mechanism.

Gene variants for the WNT pathway are associated with severity in periodontal disease

OBJECTIVE

Studies of Wnt variants-related to bone resorption in periodontitis are limited. The aim of this study was to establish the genotype and allele frequency of gene variants associated with the Wnt pathway in systemically healthy individuals with and without periodontitis (PD).

MATERIALS AND METHODS

One hundred fifty-seven systemically healthy individuals were evaluated, 90 with PD and 67 without PD. Periodontal clinical indexes, serological and clinical indices of inflammation, and the following variants associated with the Wnt pathway: DKK, SOST, LRP5, and KREMEN were analyzed by high resolution melting and confirmed by Sanger sequencing.

RESULTS

In the PD-free group, 67.2% of the individuals presented the variant for DKKrs1896367 (p = 0.008) and 82.6% had the variant for KREMEN rs132274 (p = 0.016). The heterozygous variant for the DKK rs1896367 polymorphism was associated with the absence of PD and lower severity OR: 0.33 (CI95% 0.15-0.70) and OR: 0.24 (CI95% 0.11-0.53), respectively. Similarly, KREMEN rs132274 was the homozygous variant associated with the absence of PD (OR: 0.33 (CI95% 0.13-0.88)). On the contrary, 85.6% of individuals with PD presented a variant for DKK rs1896368 (p = 0.042), all suffering severe forms of periodontitis.

CONCLUSION

The presence of DKKrs1896367 and KREMENrs132274 variants in individuals without PD suggests that these single nucleotide polymorphisms could be protective factors for bone loss in PD. A very interesting finding is that the DKKrs1896368 variant was found in a high percentage of severe cases, suggesting that the presence of this variant may be related to the severe bone loss observed in PD.

Mer tyrosine kinase regulates bone metabolism, and its deficiency partially ameliorates periodontitis- and ovariectomy-induced bone loss in mice

Bone homeostasis is maintained by tightly coordinated activities of bone-forming osteoblasts and bone-resorbing osteoclasts. In the present report, the role of Mer tyrosine kinase (MerTK) in bone metabolism was investigated. The expression of MerTK decreased upon BMP2 stimulation of osteoblast precursors. The femurs of Mertk-deficient mice showed significantly increased bone volume with concomitant increase of bone formation and reduction in bone resorption. These bone phenotypes were attributed to the increased osteoblast differentiation and mineralization accounted by the enhanced β-catenin and Smad signaling in the absence of MerTK in osteoblast precursors. Although the Mertk-deficient bone marrow macrophages were predisposed to enhanced osteoclast differentiation via augmented Ca2+-NFATc1 signaling, the dramatic increase of Tnfsf11b/Tnfsf11 (Opg/Rankl) ratio in Mertk knockout bones and osteoblast precursors corroborated the reduction of osteoclastogenesis in Mertk deficiency. In ligature-induced periodontitis and ovariectomy models, the bone resorption was significantly attenuated in Mertk-deficient mice compared with wild-type control. Taken together, these data indicate novel role of MerTK in bone metabolism and suggest a potential strategy targeting MerTK in treating bone-lytic diseases including periodontitis and osteoporosis.

Osteoprotective Role of the Mir338 Cluster Ablation during Periodontitis

Periodontitis is a chronic inflammatory disease that compromises the integrity of the supporting tissues of the teeth and leads to the loss of the alveolar bone. The Mir338 cluster has been proven to be a potential target for the treatment of osteoporosis and is also enriched in gingival tissues with periodontitis; however, its role in periodontitis remains unknown. Here, we aimed to use periodontitis as a model to expand our understanding of the Mir338 cluster in osteoimmunology and propose a new target to protect against bone loss during periodontitis progression. Significant enrichment of the Mir338 cluster was validated in gingival tissues from patients with chronic periodontitis and a ligature-induced periodontitis mouse model. In vivo, attenuation of alveolar bone loss after 7 d of ligature was observed in the Mir338 cluster knockout (KO) mice. Interestingly, immunofluorescence and RNA sequencing showed that ablation of the Mir338 cluster reduced osteoclast formation and elevated the inflammatory response, with enrichment of IFN-γ and JAK-STAT signaling pathways. Ablation of the Mir338 cluster also skewed macrophages toward the M1 phenotype and inhibited osteoclastogenesis via Stat1 in vitro and in vivo. Furthermore, the local administration of miR-338-3p antagomir prevented alveolar bone loss from periodontitis. In conclusion, the Mir338 cluster balanced M1 macrophage polarization and osteoclastogenesis and could serve as a novel therapeutic target against periodontitis-related alveolar bone loss.

Nociceptors regulate osteoimmune transcriptomic response to infection

Osteoimmune diseases, such as apical periodontitis, are prevalent, often painful, inflammatory conditions resulting in bone loss and reduced quality of life. There is growing evidence that the nociceptive fibers densely innervating affected tissues regulate disease progression; therefore, we hypothesized that nociceptors regulate the transcriptomic profile of the periapical osteolytic lesion in a mouse model of apical periodontitis. Male control and nociceptor-ablated mice underwent pulp exposures, and after 0, 7, or 14 days, total RNA from periapical tissues was submitted for sequencing and bioinformatic analysis. Pulp exposure triggers the differential expression of hundreds of genes over the course of infection. At 14 days post pulp exposure, 422 genes, including Tnf, Il1a, and Il1b, were differentially expressed between nociceptor-ablated and control mice with greater enrichment of biological processes related to inflammation in nociceptor-ablated mice. Nociceptor ablation regulates the transcriptomic profile of periapical lesions in a mouse model of apical periodontitis, shifting the gene expression profile to a greater enrichment of inflammatory genes, suggesting nociceptors play a role in the kinetics of the immune response. This newly uncovered neuro-immune axis and its mechanisms in apical periodontitis can be an important therapeutic target for the treatment of this prevalent disease.

Association between birth-related factors and periodontitis in women: Korea National Health and Nutrition Examination Survey 2013-2018

AIM

Adult women experience several changes in physiological status, such as pregnancy and childbirth, during their life cycle. This study analyses the association between birth-related factors (the number of childbirths, abortions and miscarriages) and periodontitis using data from the Korea National Health and Nutrition Examination Survey, which represents Korean adults.

MATERIALS AND METHODS

The study used data from Korea National Health and Nutrition Examination Survey VI and VII (2013-2018) and included 10,072 women 19 years or older, with no missing data on the variables assessed. Periodontitis was defined according to the Community Periodontal Index (CPI) criteria. Multiple logistic regression analysis, adjusting for age, household income, education, alcohol consumption, smoking, stress, body mass index, waist circumference, hypertension, diabetes mellitus, an oral examination within 1 year, daily tooth brushing frequency, hygiene products and self-perceived oral health as identified via logistic regression analyses, was performed to determine the association between birth-related variables and periodontitis.

RESULTS

In the crude model, the odds ratio (OR) showed a significantly increased risk of periodontitis (CPI ≥ 3) and severe periodontitis (CPI = 4) based on the number of childbirths, abortions and miscarriages (p < .05). After covariate adjustment, periodontitis (CPI ≥ 3) was associated with the number of childbirths (1: OR = 1.92; 95% confidence interval [CI]: 1.47-2.50; 2: OR = 2.03; 95% CI: 1.57-2.61; ≥3: OR = 2.11; 95% CI: 1.60-2.78). Furthermore, severe periodontitis (CPI = 4) was also associated with the number of childbirths (1: OR = 2.33; 95% CI: 1.24-4.38; 2: OR = 2.99; 95% CI: 1.62-5.52; ≥3: OR = 3.34; 95% CI: 1.79-6.21).

CONCLUSIONS

The findings of this large-scale, nationally representative study suggest that the number of childbirths is associated with the severity of periodontitis. However, the relationship between the number of abortions and miscarriages and periodontitis (CPI ≥ 3) or severe periodontitis (CPI = 4) is not significant.

Mechanical force application and inflammation induce osteoclastogenesis by independent pathways

OBJECTIVE

To investigate the functional changes of PDL fibroblasts in the presence of mechanical force, inflammation, or a combination of force and inflammation.

MATERIALS AND METHODS

Inflammatory supernatants were prepared by inoculating human neutrophils with Porphyromonas gingivalis. Primary human PDL fibroblasts (PDLF), gingival fibroblasts (GFs), and osteoblasts (Saos2) were then exposed to the inflammatory supernatants. Orthodontic force on the PDLFs was simulated by centrifugation. Analyses included cell proliferation, cell viability, cell cycle, and collagen expression, as well as osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-Β ligand (RANKL) expression.

RESULTS

Mechanical force did not affect PDLF viability, but it increased the metabolic rate compared to resting cells. Force application shifted the PDLF cell cycle to the G0/G1 phase, arresting cell proliferation and leading to elevated collagen production, mild OPG level elevation, and robust RANKL level elevation. Including an inflammatory supernatant in the presence of force did not affect PDLF viability, proliferation, or cytokine expression. By contrast, the inflammatory supernatant increased RANKL expression in GFs, but not in Saos2 cells.

CONCLUSION

Applying mechanical force significantly affects PDLF function. Although inflammation had no effect on PDLF or Saos2 cells, it promoted RANKL expression in GF cells. Within the limitations of the in vitro model, the results suggest that periodontal inflammation and mechanical forces could affect bone catabolism through effects on different cell types, which may culminate in synergistic bone resorption.

Activation of nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 6 by Porphyromonas gingivalis regulates programmed cell death in epithelium

Background/purpose

Gingival epithelial cells form a physiological barrier against bacterial invasion. Programmed cell death (PCD) regulated by pathogen precognition receptors (PRRs) lead to tissue destruction and is closely related to inflammatory diseases. The purpose of this study was to investigate whether nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 6 (NLRP6) expresses in periodontal epithelium and induces PCD of epithelial cells infected by Porphyromonas gingivalis (P. gingivalis), therefore involves in periodontitis.

Material and methods

The expression of NLRP6 was detected in periodontal epithelium from human gingival sections and HaCaT cells stimulated by P. gingivalis. NLRP6 was over-expressed by adenovirus infection in HaCaT or knocked down by siRNA in P. gingivalis infected HaCaT, and the cell death was observed by transmission electron microscopy and flow cytometry analysis. In addition, qPCR and Western blot were performed to determine the expression of NLRP6 and the pyroptosis excutors, caspase-1 and gasdermin D. Enzyme-linked immunosorbent assay were performed to detect the secretion of IL-1β and IL-18.

Results

NLRP6 was up-regulated in both gingival epithelium of patients with periodontitis and P. gingivalis infected HaCaT. Over-expression of NLRP6 in HaCaT led to caspase-1 dependent pyroptosis. Interestingly, knockdown of NLRP6 with siRNA followed by P. gingivalis stimulation inhibited pyroptosis and induced apoptosis.

Conclusion

Up-regulation of NLRP6 by P. gingivalis in HaCaT led to pyroptosis, while knocking down NLRP6 inhibited pyroptosis and induced apoptosis, which indicated this PRR may play a crucial role in periodontitis by regulating PCD in periodontal epithelium.

Bypass gastroplasty impacts oral health, salivary inflammatory biomarkers, and microbiota: a controlled study

OBJECTIVES

Knowledge about the impact of gastroplasty on oral health and salivary biomarkers is limited. The aim was to prospectively evaluate oral health status, salivary inflammatory markers, and microbiota in patients undergoing gastroplasty compared with a control group undergoing a dietary program.

MATERIALS AND METHODS

Forty participants with obesity class II/III were included (20 individuals in each sex-matched group; 23-44 years). Dental status, salivary flow, buffering capacity, inflammatory cytokines, and uric acid were assessed. Salivary microbiological analysis (16S-rRNA sequencing) assessed the abundance of genus, species, and alpha diversity. Cluster analysis and mixed-model ANOVA were applied.

RESULTS

Oral health status, waist-to-hip ratio, and salivary alpha diversity were associated at baseline. A subtle improvement in food consumption markers was observed, although caries activity increased in both groups, and the gastroplasty group showed worse periodontal status after three months. IFNγ and IL10 levels decreased in the gastroplasty group at 3 months, while a decrease was observed in the control group at 6 months; IL6 decreased in both groups (p < 0.001). Salivary flow and buffering capacity did not change. Significant changes in Prevotella nigrescens and Porphyromonas endodontalis abundance were observed in both groups, while alpha diversity (Sobs, Chao1, Ace, Shannon, and Simpson) increased in the gastroplasty group.

CONCLUSIONS

Both interventions changed in different degrees the salivary inflammatory biomarkers and microbiota, but did not improve the periodontal status after 6 months.

CLINICAL RELEVANCE

Although the observed discrete improvement in dietary habits, caries activity increased with no clinical improvement in the periodontal status, emphasizing the need of oral health monitoring during obesity treatment.

Microbiome, alveolar bone, and metabolites: Connecting the dots

The oral microbiome (OM) is a diverse and dynamic collection of species, separated from alveolar bone by the oral mucosa. Pathogenic shifts in the OM (dysbiosis) during periodontitis are associated with an inflammatory response in the oral mucosa that drives alveolar bone resorption. Alveolar bone is also affected by metabolic disorders such as osteoporosis. Accumulating evidence has linked another microbial community, the gut microbiome (GM), to systemic bone metabolism and osteoporosis. Underlying this connection is the biologic activity of metabolites, byproducts of host and bacterial activity. Limited evidence also suggests that metabolites in the oral cavity signal between the OM and immune system, influencing both alveolar bone homeostasis and pathologic bone destruction in periodontitis. While the oral cavity and gut are connected through the gastrointestinal tract, dissimilar roles for known metabolites between these two niches exemplify the difficulty in translating knowledge on gut-derived metabolites and bone metabolism to alveolar bone. Integrated metabolomic, transcriptomic, and metagenomic approaches hold promise for resolving these challenges and identifying novel metabolites which impact alveolar bone health. Further interrogation through mechanistic testing in pre-clinical models and carefully controlled clinical studies have potential to lead toward translation of these discoveries into meaningful therapies.

A vitronectin-derived peptide prevents and restores alveolar bone loss by modulating bone re-modelling and expression of RANKL and IL-17A

AIM

This study investigated whether a vitronectin-derived peptide (VnP-16) prevents and/or reverses alveolar bone resorption induced by ligature-induced periodontitis in rodents and identified the underlying mechanism.

MATERIALS AND METHODS

We evaluated the effects of VnP-16 on osteogenic differentiation in human periodontal ligament cells (hPDLCs), lipopolysaccharide-induced inflammatory responses in gingival fibroblasts, and immune response in T lymphocytes. Ligature-induced periodontitis was induced by ligating the bilateral mandibular first molars for 14 days in rats and for 7 days in mice (n = 10/group). VnP-16 (100 μg/10 μl) was applied topically into the gingival sulcus of rats via intra-sulcular injection, whereas the peptide (50 μg/5 μl) was administered directly into the gingiva of mice via intra-gingival injection. To evaluate the preventive and therapeutic effects of VnP-16, micro-computed tomography analysis and histological staining were then performed.

RESULTS

VnP-16 promoted osteogenic differentiation of periodontal ligament cells and inhibited the production of lipopolysaccharide-induced inflammatory mediators in gingival fibroblasts. Concomitantly, VnP-16 modulated the host immune response by reducing the number of receptor activator of NF-κB ligand (RANKL)-expressing lipopolysaccharide-stimulated CD4⁺ and CD8⁺ T cells, and by suppressing RANKL and interleukin (IL)-17A production. Furthermore, local administration of VnP-16 in rats and mice significantly prevented and reversed alveolar bone loss induced by ligature-induced periodontitis. VnP-16 enhanced osteoblastogenesis and simultaneously inhibited osteoclastogenesis and suppressed RANKL and IL-17A expression in vivo.

CONCLUSIONS

Our findings suggest that VnP-16 acts as a potent therapeutic agent for preventing and treating periodontitis by regulating bone re-modelling and immune and inflammatory responses.

NLRP3 Inflammasome Negatively Regulates RANKL-Induced Osteoclastogenesis of Mouse Bone Marrow Macrophages but Positively Regulates It in the Presence of Lipopolysaccharides

In inflammatory bone diseases such as periodontitis, the nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain-containing 3 (NLRP3) inflammasome accelerates bone resorption by promoting proinflammatory cytokine IL-1β production. However, the role of the NLRP3 inflammasome in physiological bone remodeling remains unclear. Here, we investigated its role in osteoclastogenesis in the presence and absence of lipopolysaccharide (LPS), a Gram-negative bacterial component. When bone marrow macrophages (BMMs) were treated with receptor activator of nuclear factor-κB ligand (RANKL) in the presence of NLRP3 inflammasome inhibitors, osteoclast formation was promoted in the absence of LPS but attenuated in its presence. BMMs treated with RANKL and LPS produced IL-1β, and IL-1 receptor antagonist inhibited osteoclastogenesis, indicating IL-1β involvement. BMMs treated with RANKL alone produced no IL-1β but increased reactive oxygen species (ROS) production. A ROS inhibitor suppressed apoptosis-associated speck-like protein containing a caspase-1 recruitment domain (ASC) speck formation and NLRP3 inflammasome inhibitors abrogated cytotoxicity in BMMs treated with RANKL, indicating that RANKL induces pyroptotic cell death in BMMs by activating the NLRP3 inflammasome via ROS. This suggests that the NLRP3 inflammasome promotes osteoclastogenesis via IL-1β production under infectious conditions, but suppresses osteoclastogenesis by inducing pyroptosis in osteoclast precursors under physiological conditions.

Analysis of Biomarkers and Marginal Bone Loss in Platform-Switched and Nonplatform-Switched Implants: A Randomized Clinical Trial

Objectives. To compare the peri-implant crevicular fluid (PICF) biomarker levels, peri-implant status, and marginal bone level (MBL) differences of implants restored with randomly assigned nonplatform-switched (NPS) or platform-switched (PS) abutments. Methods. Ninety-four implants in 27 subjects were included in this study. Receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG), interleukin-1β (IL-1β), monocyte chemotactic protein-1 (MCP-1) levels in PICF, peri-implant health, and the change in the MBL were evaluated at the time of restoration ( $T_1$ ) and after 12 months ( $T_2$ ). Results. The IL-1β levels decreased and the RANKL, OPG, and MCP-1 levels increased from $T_1$ to $T_2$ ( $P<0.05$ ) in both groups. RANKL/OPG ratio at $T_1$ , MCP-1 levels at $T_2$ , and the MCP-1 change from $T_1$ to $T_2$ were lower in the PS group than in the NPS group ( $P<0.05$ ). MBL change was lower ( $0.51\pm 0.31$  mm) in the PS group than that ( $0.75\pm 0.29$  mm) in the NPS group at $T_2$ ( $P<0.001$ ). Peri-implant health status between the study groups was negligible. Conclusion. PS was superior to NPS regarding the preservation of MBL. Higher MCP-1 levels, altered RANKL/OPG ratio, and lower OPG levels in the NPS group could be associated with subclinical peri-implant bone remodeling.

Locally Secreted Semaphorin 4D Is Engaged in Both Pathogenic Bone Resorption and Retarded Bone Regeneration in a Ligature-Induced Mouse Model of Periodontitis

It is well known that Semaphorin 4D (Sema4D) inhibits IGF-1-mediated osteogenesis by binding with PlexinB1 expressed on osteoblasts. However, its elevated level in the gingival crevice fluid of periodontitis patients and the broader scope of its activities in the context of potential upregulation of osteoclast-mediated periodontal bone-resorption suggest the need for further investigation of this multifaceted molecule. In short, the pathophysiological role of Sema4D in periodontitis requires further study. Accordingly, attachment of the ligature to the maxillary molar of mice for 7 days induced alveolar bone-resorption accompanied by locally elevated, soluble Sema4D (sSema4D), TNF-α and RANKL. Removal of the ligature induced spontaneous bone regeneration during the following 14 days, which was significantly promoted by anti-Sema4D-mAb administration. Anti-Sema4D-mAb was also suppressed in vitro osteoclastogenesis and pit formation by RANKL-stimulated BMMCs. While anti-Sema4D-mAb downmodulated the bone-resorption induced in mouse periodontitis, it neither affected local production of TNF-α and RANKL nor systemic skeletal bone remodeling. RANKL-induced osteoclastogenesis and resorptive activity were also suppressed by blocking of CD72, but not Plexin B2, suggesting that sSema4D released by osteoclasts promotes osteoclastogenesis via ligation to CD72 receptor. Overall, our data indicated that ssSema4D released by osteoclasts may play a dual function by decreasing bone formation, while upregulating bone-resorption.

Meta-Analysis of Two Human RNA-seq Datasets to Determine Periodontitis Diagnostic Biomarkers and Drug Target Candidates

Periodontitis is a chronic inflammatory oral disease that affects approximately 42% of adults 30 years of age or older in the United States. In response to microbial dysbiosis within the periodontal pockets surrounding teeth, the host immune system generates an inflammatory environment in which soft tissue and alveolar bone destruction occur. The objective of this study was to identify diagnostic biomarkers and the mechanistic drivers of inflammation in periodontitis to identify drugs that may be repurposed to treat chronic inflammation. A meta-analysis comprised of two independent RNA-seq datasets was performed. RNA-seq analysis, signal pathway impact analysis, protein-protein interaction analysis, and drug target analysis were performed to identify the critical pathways and key players that initiate inflammation in periodontitis as well as to predict potential drug targets. Seventy-eight differentially expressed genes, 10 significantly impacted signaling pathways, and 10 hub proteins in periodontal gingival tissue were identified. The top 10 drugs that may be repurposed for treating periodontitis were then predicted from the gene expression and pathway data. The efficacy of these drugs in treating periodontitis has yet to be investigated. However, this analysis indicates that these drugs may serve as potential therapeutics to treat inflammation in gingival tissue affected by periodontitis.

Comparison of Physicochemical, Mechanical, and (Micro-)Biological Properties of Sintered Scaffolds Based on Natural- and Synthetic Hydroxyapatite Supplemented with Selected Dopants

The specific combinations of materials and dopants presented in this work have not been previously described. The main goal of the presented work was to prepare and compare the different properties of newly developed composite materials manufactured by sintering. The synthetic- (SHAP) or natural- (NHAP) hydroxyapatite serves as a matrix and was doped with: (i) organic: multiwalled carbon nanotubes (MWCNT), fullerenes C60, (ii) inorganic: Cu nanowires. Research undertaken was aimed at seeking novel candidates for bone replacement biomaterials based on hydroxyapatite—the main inorganic component of bone, because bone reconstructive surgery is currently mostly carried out with the use of autografts; titanium or other non-hydroxyapatite -based materials. The physicomechanical properties of the developed biomaterials were tested by Scanning Electron Microscopy (SEM), Dielectric Spectroscopy (BSD), Nuclear Magnetic Resonance (NMR), and Differential Scanning Calorimetry (DSC), as well as microhardness using Vickers method. The results showed that despite obtaining porous sinters. The highest microhardness was achieved for composite materials based on NHAP. Based on NMR spectroscopy, residue organic substances could be observed in NHAP composites, probably due to the organic structures that make up the tooth. Microbiology investigations showed that the selected samples exhibit bacteriostatic properties against Gram-positive reference bacterial strain S. epidermidis (ATCC 12228); however, the property was much less pronounced against Gram-negative reference strain E. coli (ATCC 25922). Both NHAP and SHAP, as well as their doped derivates, displayed in good general compatibility, with the exception of Cu-nanowire doped derivates.

Sustained Release of Risedronate from PLGA Microparticles Embedded in Alginate Hydrogel for Treatment of Bony Lesions

Background:

Inflammatory bone resorption in periodontitis can lead to tooth loss. Systemic administration of bisphosphonates such as risedronate for preventing bone resorption can cause adverse effects. ALG and PLGA microparticles have been studied as drug delivery systems for sustained release of drugs. Therefore, the release pattern of risedronate from PLGA microparticles embedded with ALG was studied as a drug delivery system for sustained release of the drug, which can be used in local administrations.

Methods:

Risedronate-containing PLGA microparticles were fabricated using double emulsion solvent evaporation technique. Ionic cross-linking method was used to fabricate risedronate-loaded ALG. Risedronate-containing PLGA microparticles were then coated with ALG. The calibration curve of risedronate was traced to measure EE and study the release pattern. SEM imaging was carried out, and cell toxicity was examined using MTT assay. Statistical analysis of data was carried out using SPSS ver. 20 software, via one-way ANOVA and Tukey’s tests.

Results:

SEM imaging showed open porosities on ALGs. The mean EE of PLGA microparticles for risedronate was 57.14 ± 3.70%. Risedronate released completely after 72 h from ALG, and the cumulative release was significantly higher (p = 0.000) compared to PLGA microspheres coated with ALG, which demonstrated sustained released of risedronate until day 28. Risedronate-loaded ALG showed a significant decrease in gingival fibroblasts cell viability (p < 0.05).

Conclusion:

Alginate-coated PLGA microspheres could release risedronate in a sustained and controlled way and also did not show cell toxicity. Therefore, they seem to be an appropriate system for risedronate delivery in local applications.

Myeloid-Specific PTP1B Deficiency Attenuates Inflammation-Induced and Ovariectomy-Induced Bone Loss in Mice by Inhibiting Osteoclastogenesis

The differentiation and activity of bone-resorbing osteoclasts are tightly regulated to maintain the homeostasis of healthy bones. In this study, the role of protein tyrosine phosphatase 1B (PTP1B) during osteoclastogenesis was studied in myeloid-specific Ptpn1-deficient (conditional knockout [cKO]) mice. The mRNA and protein expression of PTP1B increased during the formation of mature osteoclasts from mouse bone macrophages on stimulation with macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor κB ligand (RANKL). The Ptpn1 cKO mice exhibited increased femoral trabecular bone volume with a decreased number and activity of osteoclasts compared with control mice. The in vitro culture of osteoclast precursors corroborated the inhibition of osteoclastogenesis in cKO cells compared with control, with concomitantly decreased RANKL-dependent proliferation, lower osteoclast marker gene expression, reduced nuclear expression of nuclear factor of activated T cells cytoplasmic 1 (NFATc1), diminished intracellular Ca²⁺ oscillations, and increased phosphorylation of proto-oncogene tyrosine-protein kinase Src on inhibitory tyrosine residue. In a ligature-induced periodontitis model, Ptpn1 cKO mice exhibited attenuated osteoclastogenesis and alveolar bone loss following the induction of inflammation. The Ptpn1-deficient mice were similarly protected from ovariectomy-induced bone loss compared with control mice. These results provide a novel regulatory role of PTP1B in osteoclastogenesis and suggest a potential as a therapeutic target for bone-lytic diseases. © 2021 American Society for Bone and Mineral Research (ASBMR).

DNA damage-inducible transcript 3 restrains osteoclast differentiation and function

DNA damage-inducible transcript 3 (DDIT3), a member of the CCAAT/enhancer-binding protein (C/EBP) family, is involved in cellular apoptosis and differentiation. DDIT3 participates in the regulation of adipogenesis and osteogenesis in vitro and in vivo. However, the role of DDIT3 in osteoclastogenesis is not yet known. In this study, the involvement of DDIT3 in osteoclast differentiation and function was reported for the first time. CRISPR/Cas9-mediated DDIT3 knockout (KO) mice were generated for functional assessment. Tartrate-resistant acid phosphatase (TRAP) staining of distal femurs showed increased positive cells in DDIT3 KO mice. DDIT3 expression was downregulated during the receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation of bone marrow-derived macrophages (BMMs). The loss of DDIT3 increased the expression of osteoclast-specific markers, including nuclear factor of activated T-cells cytoplasmic 1 (NFATc1), TRAP, cathepsin K (CTSK), and dendritic cell-specific transmembrane protein (DC-STAMP) and promoted the formation of TRAP-positive multinucleated osteoclasts. The actin ring number and resorption area of bone slices were also increased in DDIT3 KO BMMs. Lentivirus-mediated DDIT3 overexpression significantly inhibited the osteoclast differentiation of RAW264.7 cells. In the tumor necrosis factor-α-induced osteolysis model, DDIT3 deficiency enhanced osteoclast formation and aggravated bone resorption. DDIT3 inhibited osteoclast differentiation by regulating the C/EBPα-CTSK axis. Furthermore, DDIT3 KO intensified the RANKL-triggered activation of the MAPKs and Akt signaling pathways. Taken together, the results revealed the essential role of DDIT3 in osteoclastogenesis in vitro and in vivo and its close relationship with osteoclast-associated transcription factors and pathways.

Association of Serum and Crevicular Fluid Dickkopf-1 Levels with Disease Activity and Periodontitis in Patients with Early Rheumatoid Arthritis

BACKGROUND

The aim of this study was to assess DKK-1 levels, in Gingival Crevicular Fluid (GCF) and serum, as a biomarker for bone loss and disease activity in periodontitis and early RA (eRA).

METHODS

In this cross-sectional study, we obtained serum and GCF from 10 interproximal sites (Distal Buccal I/S, Mesio Buccal I/S, Distal Palatal/Lingual, Mesio Palatal/Lingual) according to the highest degree of inflammation by a patient for 240 sites from eRA patients. Patients received a periodontal assessment, a radiographic evaluation, tomography of interproximal sites, and DKK1 levels were determined by ELISA. Comparisons were performed by the Mann-Whitney U test and analysis by Chi2 test, and a logistic regression model was applied.

RESULTS

The mean age was 46.33 ± 12.0 years, the Disease Activity Score (DAS-28-ESR) was 4.08 ± 1.4. Periodontitis was present in 65.2% of the patients, and 59.6% of these patients had bone loss in interproximal sites. Higher GCF-DKK1 levels were associated with serum-DKK1 (OR:2.41 IC95% 1.14-5.09, p=0.021) and were related with DAS28-ESR (p=0.001), Routine Assessment of Patient Index Data 3 (RAPID 3) (p=0.001), and tender joints (p=0.040). Foot bone erosion and juxta-articular osteopenia were associated with high levels of serum-DKK1 (p=0.009 and 0.001, respectively). Serum-DKK1 were associated with SDAI (OR: 2.38 IC95% 1.03-5.52, p=0.043), RAPID 3 (p=0.001), and rheumatoid factor (p=0.018). The GCF-DKK1 levels were associated with periodontal bone loss (p=0.011), periodontitis (p=0.070) and its severity (OR: 2.58 IC95% 2.28-7.28, p=0.001). Bone loss was more frequent in buccal sites (73.5%) and was associated with increased levels of DKK1 (p=0.033).

CONCLUSION

In the early stages of the eRA disease, serum and GCF-DKK1 could be a biomarker for clinical disease activity and periodontal and articular bone erosion.

Hexokinase 2-mediated glycolysis promotes receptor activator of NF-κB ligand expression in Porphyromonas gingivalis lipopolysaccharide-treated osteoblasts

BACKGROUND

Glucose metabolism plays a pivotal role in sustaining the inflammatory response to microbial stimulation by providing sufficient energy in immune cells. The main purpose of our study was to explore whether hexokinase 2 (HK2)-mediated glycolysis affected the expression of receptor activator of NF-κB Ligand (RANKL) in Porphyromonas gingivalis lipopolysaccharide (P. gingivalis-LPS)-treated osteoblasts and evaluate the potential involvement of the AKT/PI3K pathway activation during HK2-mediated glycolysis.

METHODS

Primary mice osteoblasts were treated with P. gingivalis-LPS, whereas the HK2 inhibitor (Lonidamine, LND) and small interference RNA were used to restrain HK2 expression. Conditioned medium from osteoblasts was utilized for culturing osteoclast precursors. The mRNA and protein levels of genes involved in glycolysis and bone metabolism including RANKL and osteoprotegerin (OPG) were detected by real-time PCR and western blotting. HK2 and lactate levels were detected by ELISA. Tartrate-resistant acid phosphatase (TRAP) staining was utilized to assess osteoclast formation. The involvement of the AKT/PI3K pathway in osteoblasts was explored by Western blotting.

RESULTS

P. gingivalis-LPS enhanced HK2 expression along with rising glycolysis in osteoblasts. LND and HK2-knockdown decreased RANKL expression and the RANKL/OPG ratio in osteoblasts, leading to less osteoclast formation from osteoclast precursors as evidenced by TRAP staining, while the osteogenic potential and proliferation of osteoblasts were not affected by HK2-knockdown. Moreover, P. gingivalis-LPS activated the AKT/PI3K pathway, which could regulate HK2 and RANKL expression in osteoblasts.

CONCLUSIONS

HK2-mediated glycolysis promoted RANKL in osteoblasts and enhanced osteoclast differentiation. Targeting glycolysis may provide novel therapeutic methods for reducing alveolar bone loss.

Effects of curcumin gel on osteoclastogenic bone markers in experimental periodontitis and alveolar bone loss in wistar rats

BACKGROUND/PURPOSE

Curcumin has anti-inflammatory impacts and was suggested as an inflammatory disease therapy. This study aimed to investigate the implications of curcumin gel on experimental periodontitis (EPD) and alveolar bone loss in rats.

MATERIALS AND METHODS

In this study, twenty-four male Wistar rats were divided equally into four groups: negative control (with no EPD); positive control (EPD induced around lower centrals without treatment); control-treated group: EPD treated with chlorhexidine; and test EPD group treated with curcumin. After 30 days, the serum concentrations of RANKL and IL-1β were measured via ELISA. All animals were sacrificed, and mandibular central incisors with the periodontium were removed. The lingual probing depth and radiographical alveolar bone loss were measured, then samples processed for routine preparation of H&E stained sections and histologically assessed for counting inflammatory cells, osteoclasts, and PDL width.

RESULTS

A significant decrease in the inflammatory cells infiltration, probing depth, and osteoclast numbers with the improvement of PDL associated with a reduction in RANKL and IL-1β serum concentration were seen in both EPD treated groups.

CONCLUSION

Curcumin is as effective as chlorhexidine in treating experimental periodontitis in rats. It was demonstrated to stop bone destruction related to periodontitis by regulating the RANKL and IL-1β markers level in the blood.

Local Sustained Delivery of Anti-IL-17A Antibodies Limits Inflammatory Bone Loss in Murine Experimental Periodontitis

Periodontal disease (PD) is a chronic destructive inflammatory disease of the tooth-supporting structures that leads to tooth loss at its advanced stages. Although the disease is initiated by a complex organization of oral microorganisms in the form of a plaque biofilm, it is the uncontrolled immune response to periodontal pathogens that fuels periodontal tissue destruction. IL-17A has been identified as a key cytokine in the pathogenesis of PD. Despite its well documented role in host defense against invading pathogens at oral barrier sites, IL-17A-mediated signaling can also lead to a detrimental inflammatory response, causing periodontal bone destruction. In this study, we developed a local sustained delivery system that restrains IL-17A hyperactivity in periodontal tissues by incorporating neutralizing anti-IL-17A Abs in poly(lactic-coglycolic) acid microparticles (MP). This formulation allowed for controlled release of anti-IL-17A in the periodontium of mice with ligature-induced PD. Local delivery of anti-IL-17A MP after murine PD induction inhibited alveolar bone loss and osteoclastic activity. The anti-IL-17A MP formulation also decreased expression of IL-6, an IL-17A target gene known to induce bone resorption in periodontal tissues. This study demonstrates proof of concept that local and sustained release of IL-17A Abs constitutes a promising therapeutic strategy for PD and may be applicable to other osteolytic bone diseases mediated by IL-17A-driven inflammation.

Quercetin reverses TNF‑α induced osteogenic damage to human periodontal ligament stem cells by suppressing the NF‑κB/NLRP3 inflammasome pathway

Quercetin (Quer) is a typical antioxidant flavonoid from plants that is involved in bone metabolism, as well as in the progression of inflammatory diseases. Elevated levels of tumor necrosis factor-α (TNF-α), a typical pro-inflammatory cytokine, can affect osteogenesis. In the present study, TNF-α was used to establish an in vitro model of periodontitis. The effects of Quer on, as well as its potential role in the osteogenic response of human periodontal ligament stem cells (hPDLSCs) under TNF-α-induced inflammatory conditions and the underlying mechanisms were then investigated. Within the appropriate concentration range, Quer did not exhibit any cytotoxicity. More importantly, Quer significantly attenuated the TNF-α induced the suppression of osteogenesis-related genes and proteins, alkaline phosphatase (ALP) activity and mineralized matrix in the hPDLSCs. These findings were associated with the fact that Quer inhibited the activation of the NF-κB signaling pathway, as well as the expression of NLRP3 inflammation-associated proteins in the inflammatory microenvironment. Moreover, the silencing of NLRP3 by small interfering RNA (siRNA) was found to protect the hPDLSCs against TNF-α-induced osteogenic damage, which was in accordance with the effects of Quer. On the whole, the present study demonstrates that Quer reduces the impaired osteogenesis of hPDLSCs under TNF-α-induced inflammatory conditions by inhibiting the NF-κB/NLRP3 inflammasome pathway. Thus, Quer may prove to be a potential remedy against periodontal bone defects.

Gan-Lu-Yin (Kanroin), Traditional Chinese Herbal Extracts, Reduces Osteoclast Differentiation In Vitro and Prevents Alveolar Bone Resorption in Rat Experimental Periodontitis

Gan-Lu-Yin (GLY), a traditional Chinese herbal medicine, shows therapeutic effects on periodontitis, but that mechanism is not well known. This study aims to clarify the precise mechanism by investigating the inhibitory effects of GLY extracts on osteoclastogenesis in vitro and on bone resorption in periodontitis in vivo. RAW264.7 cells are cultured with soluble receptor activator of nuclear factor-kappa B (sRANKL) and GLY extracts (0.01–1.0 mg/mL), and stained for tartrate-resistant acid phosphatase (TRAP) to evaluate osteoclast differentiation. Experimental periodontitis is induced by placing a nylon ligature around the second maxillary molar in rats, and rats are administered GLY extracts (60 mg/kg) daily for 20 days. Their maxillae are collected on day 4 and 20, and the levels of alveolar bone resorption and osteoclast differentiation are estimated using micro-computed tomography (CT) and histological analysis, respectively. In RAW264.7 cells, GLY extracts significantly inhibit sRANKL-induced osteoclast differentiation at a concentration of more than 0.05 mg/mL. In experimental periodontitis, administering GLY extracts significantly decreases the number of TRAP-positive osteoclasts in the alveolar bone on day 4, and significantly inhibits the ligature-induced bone resorption on day 20. These results show that GLY extracts suppress bone resorption by inhibiting osteoclast differentiation in experimental periodontitis, suggesting that GLY extracts are potentially useful for oral care in periodontitis.

Periodontal inflammation triggers a site-specific and wide radius of calcium metabolic effects on alveolar bone

BACKGROUND AND OBJECTIVE

There is a close relationship between inflammation and bone remodeling in the periodontium. However, previous studies have not delineated the alterations in calcium (Ca) metabolism during periodontitis progression. The aim of this current investigation was to examine Ca dynamics in alveolar bone of rats during progression of ligature-induced periodontal inflammation by using ⁴⁵ Ca, which is an index of hard tissue neogenesis.

MATERIAL AND METHODS

To induce periodontitis, the maxillary right first molar (M1) of 8-week-old male rats was ligated with a silk suture for 1, 3, 7, and 28 days. The left M1 was not ligated as a control. To evaluate resultant changes in bone neogenesis, ⁴⁵ CaCl₂ was injected intraperitoneally 24 hours before euthanasia. The left-and-right palatal mucosa, molar teeth (M1 and M2), and alveolar bone were harvested for evaluation of ⁴⁵ Ca radioactivity using a liquid scintillation counter. The distribution of ⁴⁵ Ca in maxillary tissues was evaluated using autoradiography (ARG). In addition, we analyzed the bone volume fraction (BV/TV) and bone mineral density (BMD) of the alveolar bone by micro-computed tomography. To investigate the number of osteoclasts and osteoblasts, tartrate-resistant acid phosphatase (TRAP) and bone-specific alkaline phosphatase (BAP) were measured by an enzymatic assay and immunohistochemistry, respectively.

RESULTS

⁴⁵ Ca radioactivity in the alveolar bone of the ligature side decreased by 8% compared to the unligated control-side on day 1, whereas on day 7, it markedly increased by 33%. The ⁴⁵ Ca levels in the gingival tissue and molar teeth were slightly but significantly lower than the control-side on day 1 and higher from day 3 to 28. The variation in ⁴⁵ Ca levels for the alveolar bone was greater and specific compared with other tissues. Furthermore, on day 7, ARG data revealed that ⁴⁵ Ca on the control side was primarily localized to the periodontal ligament (PDL) space and alveolar bone crest and barely detected in the gingival tissues and deeper parts of the alveolar bone. On the ligature side, ⁴⁵ Ca disappeared from the PDL and alveolar crest, but instead was broadly and significantly increased within the deeper zones of the alveolar bone and furcation areas and distant from the site of ligature placement and periodontal inflammation. In the shallow zone of the alveolar bone, these changes in ⁴⁵ Ca levels on day 7 were consistent with decreases in the bone structural parameters (BV/TV and BMD), enhanced osteoclast presence, and suppressed levels of BAP expression in osteoblasts. In contrast, the deep zone and furcation area showed that TRAP-positive cells increased, but BAP expression was maintained in the resorption lacunae of the alveolar bone.

CONCLUSION

During periodontitis progression in rats, ⁴⁵ Ca levels in the alveolar bone exhibited biphasic alterations, namely decreases and increases. These data indicate that periodontitis induces a wide range of site-specific Ca metabolism alterations within the alveolar bone.

Therapeutic Functions of Stem Cells from Oral Cavity: An Update

Adult stem cells have been developed as therapeutics for tissue regeneration and immune regulation due to their self-renewing, differentiating, and paracrine functions. Recently, a variety of adult stem cells from the oral cavity have been discovered, and these dental stem cells mostly exhibit the characteristics of mesenchymal stem cells (MSCs). Dental MSCs can be applied for the replacement of dental and oral tissues against various tissue-damaging conditions including dental caries, periodontitis, and oral cancers, as well as for systemic regulation of excessive inflammation in immune disorders, such as autoimmune diseases and hypersensitivity. Therefore, in this review, we summarized and updated the types of dental stem cells and their functions to exert therapeutic efficacy against diseases.

6-Shogaol, an active ingredient of ginger, inhibits osteoclastogenesis and alveolar bone resorption in ligature-induced periodontitis in mice

BACKGROUND

Periodontitis is an inflammatory disease of the tissues surrounding teeth that causes destruction of connective tissues. During the progress of periodontitis, osteoclasts are solely accountable for the resorption of alveolar bones that leads to the loss of teeth if not properly treated. Thus, the development of effective anti-resorptive therapies will greatly benefit the treatment of periodontitis patients. In the present study, we suggest an inhibitory effect of 6-shogaol, an ingredient of ginger, on osteoclast differentiation and bone resorption.

METHODS

Mouse bone marrow cells were cultured in the presence of macrophage-colony stimulating factor and receptor activator of nuclear factor-κB ligand (RANKL) to investigate the effect of 6-shogaol on osteoclast differentiation and intracellular signaling pathways. 6-shogaol significantly reduced osteoclast differentiation, actin ring formation, and resorption. In the presence of 6-shogaol, osteoclast signaling including the RANKL-induced activation of mitogen-activated protein kinases, Ca2+ oscillation, generation of reactive oxygen species, and nuclear factor of activated T-cells, cytoplasmic 1 nuclear translocation was significantly inhibited in vitro. Furthermore, a ligature-induced periodontitis model in mice was used to determine the role of 6-shogaol in vivo.

RESULTS

The administration of 6-shogaol prevented osteoclastogenesis and alveolar bone resorption induced by ligature. Furthermore, the ligature-induced number of macrophages and neutrophils as well as the expression of interleukin-1β and tumor necrosis factor-α were considerably lower in the periodontal tissues following shogaol injection.

CONCLUSION

These results confirm the anti-osteoclastogenic effect of 6-shogaol and suggest the possibility of application as an anti-resorptive strategy in periodontitis.

Biomarker for Asymptomatic Apical Periodontitis in Gingival Crevicular Fluid: aMMP-8

Objectives  Asymptomatic apical periodontitis (AAP) is one of the most widespread chronic inflammatory diseases in the field of dental medicine. Active matrix metalloproteinase (aMMP-8) previously demonstrated diagnostic potential as a biomarker for AAP in gingival crevicular fluid (GCF). The aim of this study was to determine the levels and diagnostic accuracy of aMMP-8 in GCF from teeth with AAP.

Materials and Methods  In this cross-sectional study, GCF samples were obtained from teeth with AAP (sample group, n = 31) and their contralateral teeth (control group, n = 31). Clinical and cone beam computed tomography (CBCT) parameters were used for the diagnosis and assessment of AAP and the determination of clinically healthy marginal periodontal tissues. One pool GCF sample per tooth was obtained from the whole crevice’s perimeter. aMMP-8 levels were determined by enzyme-linked immunosorbent assay (ELISA).

Statistical Analysis  Wilcoxon signed ranks test and Spearman rank correlation coefficient (rs) were used as statistical tools. The significance level was set at p < .05.

Results  The two groups demonstrated biomarker levels corresponding to a healthy marginal periodontal tissue. aMMP-8 levels were statistically and significantly higher in the samples collected from teeth with AAP. Lesions with greater volume showed correspondingly larger diameters. No statistically significant correlation between aMMP-8 levels and lesions’ volume or diameter was discovered.

Conclusion  GCF composition is modified by AAP only to a minimal extent. Further research is needed to substantiate the utilization of aMMP-8 as a potential biomarker for the diagnosis of the disease as well as to explore its relationship with other biomarkers.

Endogenous Collagenases Regulate Osteoclast Fusion

The precise regulation of osteoclast differentiation and function is crucial for the maintenance of healthy bone. Despite several reports of collagenase expression in bone tissues, the precise isoform expression as well as the role in osteoclasts are still unclear. In the present report, the expression of matrix metalloprotease (MMP)8 and MMP13 was confirmed in mouse bone marrow macrophage osteoclast precursors. The mRNA and protein expressions of both collagenases were significantly reduced by receptor activator of nuclear factor κB ligand (RANKL) stimulation. Notably, either inhibition of MMP expression by siRNA or treatment of cells with collagenase inhibitor Ro 32-3555 significantly augmented osteoclast fusion and resorption activity without affecting the osteoclast number. The inhibition of collagenase by Ro 32-3555 increased the expression of osteoclast fusion genes, Atp6v0d2 and Dcstamp, without affecting nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) protein expression. The enhanced osteoclast fusion by collagenase inhibition appears to be mediated through an extracellular signal regulated kinase (ERK)-dependent pathway. Collectively, these data provide novel information on the regulation of osteoclast fusion process.

Plasma rich in growth factors (PRGF) in non-surgical periodontal therapy: a randomized clinical trial

The aim of this split mouth, double blinded, randomized clinical trial was to evaluate the clinical efficacy of use of Plasma rich in growth factors (PRGF) as an adjunct to scaling and root planing (SRP) in the treatment of periodontal pockets. Twenty six patients (15 males, 11 females) diagnosed with generalized periodontitis with Pocket Depth > 5mm and plaque index score < 1.5, were randomly allocated by using computer generated random sequence, into two groups, one treated with intra-pocket application of PRGF adjunct to SRP and other with SRP alone. The clinical outcomes like pocket depth (PD), relative attachment level (RAL) and sulcus bleeding index (SBI) were assessed at baseline, 3 months and 6 months. Twenty two patients (44 sites) were analyzed at the end of 6 month follow-up, using SPSS 20.0v software. There was a significant statistical difference observed between both the groups favouring SRP +PRGF group in terms of PD (p = 0.007) and RAL (p = 0.021) at the end of 6 month follow-up. Also there was a statistical significant difference (< 0.001) at all time points compared to baseline, for all parameters in intra-group comparison. Moreover, the sites with PD>4mm necessitating further treatment after 6-month follow-up were significantly lesser for SRP+PRGF group. The use of PRGF technology in non-surgical periodontal therapy, by single intra-pocket application in to periodontal pockets as an adjunct to SRP, in chronic periodontitis patients, was found to be effective in reduction of pocket depth and gain in clinical attachment level.

Is low level laser therapy or ozone therapy more effective for bone healing? Understanding the mechanisms of HIF-1α, RANKL and OPG

Periodontitis is a common chronic infection of dental tissues. Ozone therapy (OT) and low level laser therapy (LLLT) are useful treatments for periodontitis. We investigated the effects of OT and LLLT on periodontal disease-induced bone destruction in rats with experimentally induced periodontitis (EP). We used 30 male Wistar rats divided into three groups: control, OT and LLLT. EP was induced by placing a 3.0 silk suture around the cervix of the left mandibular first molar tooth. OT was performed using an ozone generator at 80% concentration. LLLT was applied using a diode laser. Both OT and LLLT were performed for two weeks at two day intervals. Histomorphometric and immunohistochemical analyses also were performed. Alveolar bone loss was significantly less in the LLLT group compared to the control group. The number of HIF-1α positive cells was significantly less in the LLLT group compared to the control group. We found significantly fewer RANKL-positive cells in the OT group compared to the control group. The number of osteoprotegerin (OPG) positive cells was significantly greater for the LLLT group than for the control group. Although both treatments produced positive effects, LLLT appears to be more effective for increasing alveolar bone formation.

Resveratrol rescues TNF‑α‑induced inhibition of osteogenesis in human periodontal ligament stem cells via the ERK1/2 pathway

Periodontitis is a common inflammatory disorder affecting the tissues surrounding the teeth, which can lead to the destruction of periodontal tissue and tooth loss. Resveratrol, a natural phytoalexin, exerts multiple biological effects. For example, its anti-inflammatory activity has been widely studied for the treatment of inflammatory bowel disease for a number of years. However, its effect on bone repair and new bone formation in an inflammatory microenvironment is not well understood. Accordingly, the effect of resveratrol on inflammation-affected human periodontal ligament stem cells (hPDLSCs) requires further investigation. In the present study, the effect of tumor necrosis factor-α (TNF-α), resveratrol, or the combination of both on the osteogenic differentiation of hPDLSCs, as well as the underlying mechanisms involved, were investigated. Cell Counting Kit-8 assay, alkaline phosphatase staining, Alizarin red staining, Oil Red O staining, reverse transcription-quantitative PCR and western blotting were used in the present study. It was demonstrated that resveratrol enhanced hPDLSC osteogenesis and reversed the inhibitory effects of TNF-α on this process. Further mechanistic studies indicated that resveratrol exerted anti-inflammatory activity by activating the ERK1/2 pathway, decreasing the secretion of interleukin (IL)-6 and IL-8 induced by TNF-α, and enhancing hPDLSCs osteogenesis. The present study suggested that resveratrol may be a novel and promising therapeutic choice for periodontitis.

IL-17 promotes osteoblast differentiation, bone regeneration, and remodeling in mice

Bone homeostasis is maintained by concerted actions of bone-forming osteoblasts and bone-resorbing osteoclasts. A wide range of evidence indicates that a proinflammatory cytokine IL-17 promotes osteoclastogenesis. However, the role of IL-17 in osteoblasts is less well-understood. In the current study, the effect of IL-17 on osteogenic differentiation was investigated in mouse calvarial cells. IL-17 stimulated osteoblast differentiation, mineralization, proliferation, motility, and osteoblast-dependent osteoclastogenesis in vitro. The pro-osteogenic role of IL-17 was dependent on Act1 and the generation of reactive oxygen species. In a critical size calvarial defect model, IL-17 significantly augmented bone regeneration. Importantly, IL-17 also remarkably increased bone remodeling and restored osteoclastogenesis in zoledronate-treated mice. Furthermore, IL-17 conspicuously stimulated the formation of lamellar bones. These data not only provide a clue to understand the role of IL-17 in bone metabolism but also suggest possible applications in bone augmentation therapies.

Enhancement of periodontal tissue regeneration by conditioned media from gingiva-derived or periodontal ligament-derived mesenchymal stem cells: a comparative study in rats

BACKGROUND

Evidence has demonstrated conditioned medium (CM) from periodontal ligament stem cells (PDLSCs) improved periodontal regeneration. Gingival mesenchymal stem cells (GMSCs) have been considered an alternative strategy for regenerative medicine. To determine whether GMSC-CM could promote periodontal wound healing, we compared the effects of GMSC-CM and PDLSC-CM on periodontal regeneration and the underlying mechanisms in rat periodontal defects.

METHODS

Cell-free CMs were collected from PDLSCs, GMSCs, and gingival fibroblasts (GFs) using ultracentrifugation (100-fold concentration). Periodontal defects were created on the buccal side of the first molar in the left mandible of 90 rats by a surgical method. Collagen membranes loaded with concentrated CMs (α-MEM, GF-CM, GMSC-CM, PDLSC-CM) were transplanted into periodontal defects. After 1, 2, and 4 weeks, the animals were sacrificed and specimens including the first molar and the surrounding tissues were separated and decalcified. Hematoxylin-eosin and Masson's trichrome staining were performed to evaluate periodontal regeneration. Immunohistochemical staining for tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-10 was conducted to analyze inflammation. Immunohistochemistry of BSP-II and Runx2 was performed to analyze osteoblast differentiation.

RESULTS

Histological analysis showed the amount of newly formed periodontal tissue was significantly higher in both the GMSC-CM and PDLSC-CM groups than in the other groups, with no significant difference between these two groups. At 1 and 2 weeks, the expression levels of TNF-α and IL-1β were significantly lower in the GMSC-CM and PDLSC-CM groups than in the other three groups, while there was no significant difference between these two groups. IL-10 expression was significantly higher in the GMSC-CM group than in the PDLSC-CM group and the other three groups. At 1, 2, and 4 weeks, BSP-II and Runx2 expressions were significantly higher in the GMSC-CM and PDLSC-CM groups than in the other three groups, with no significant difference between the two groups.

CONCLUSIONS

Our results demonstrate that GMSC-CM transplantation can significantly promote periodontal regeneration in rats and achieve the same effect as PDLSC-CM. The mechanism of periodontal regeneration may involve the regulation of inflammatory factors and the promotion of osteogenic differentiation of bone progenitor cells in the wound region by CMs from MSCs.

Evaluation of the clinical efficacy of 1.2% atorvastatin in the treatment of periodontal intraosseous defects by CBCT: A randomized controlled clinical trial

Background. Atorvastatin (ATV), which belongs to the statin class of drugs, is the formidable inhibitor of 3-hydroxy-2- methyl-glutaryl coenzyme A reductase. This clinical trial evaluated and compared the clinical and radiographic changes in chronic periodontitis (CP) patients, obtained through 1.2% ATV as an adjunct to scaling and root planing (SRP) in the treatment of intraosseous defects. Methods. Twenty CP patients, with a minimum of one pair of bilateral intraosseous, were randomly selected for this splitmouth study. Group 1 included 20 sites treated with SRP and subgingival delivery of a placebo gel, whereas an equal number of sites in group 2 were treated by SRP along with subgingival delivery of 1.2% ATV gel. The plaque index (PI), modified sulcus bleeding index (mSBI), probing pocket depth (PPD) and clinical attachment level (CAL) were evaluated at baseline and 3- and 6-month intervals, while the intraosseous defect was assessed at baseline and 6-month interval using cone-beam computed tomography (CBCT). Paired t-test was used to determine statistical significance. Results. A greater reduction in the mean PPD and gain in CAL was found in group 2 compared to group 1 at 3- and 6-month intervals. Furthermore, a significantly greater bone fill was obtained in group 2 (1.70±0.54 mm) compared to group 1 (0.22±0.43 mm) after six months. Conclusion. ATV, as an adjunct to SRP, enhanced periodontal regeneration, as a noninvasive way to treat periodontal intraosseous defects.

Mesenchymal stem cells and biologic factors leading to bone formation

BACKGROUND

Physiological bone formation and bone regeneration occurring during bone repair can be considered distinct but similar processes. Mesenchymal stem cells (MSC) and associated biologic factors are crucial to both bone formation and bone regeneration.

AIM

To perform a narrative review of the current literature regarding the role of MSC and biologic factors in bone formation with the aim of discussing the clinical relevance of in vitro and in vivo animal studies.

METHODS

The literature was searched for studies on MSC and biologic factors associated with the formation of bone in the mandible and maxilla. The search specifically targeted studies on key aspects of how stem cells and biologic factors are important in bone formation and how this might be relevant to bone regeneration. The results are summarized in a narrative review format.

RESULTS

Different types of MSC and many biologic factors are associated with bone formation in the maxilla and mandible.

CONCLUSION

Bone formation and regeneration involve very complex and highly regulated cellular and molecular processes. By studying these processes, new clinical opportunities will arise for therapeutic bone regenerative treatments.

Effects of colchicine on gingival inflammation, apoptosis, and alveolar bone loss in experimental periodontitis

BACKGROUND

The aim of the study was to investigate the effects of colchicine on cytokine production, apoptosis, alveolar bone loss, and oxidative stress in an experimental model of periodontitis in rats.

METHODS

Forty-eight rats were divided equally into four groups: healthy (H); periodontitis (P); periodontitis+colchicine low dose (CL, 30 μg/kg/day), and periodontitis+colchicine high dose (CH, 100 μg/kg/day). After 11 days, interleukin (IL) -1β, IL-8, and IL-10 were analyzed in gingival samples using Enzyme-Linked ImmunoSorbent Assay. Receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG), total oxidative stress (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) were measured in gingiva and serum. Alveolar bone volume was evaluated via micro-CT. Apoptotic cells were detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay in histological sections.

RESULTS

Colchicine treatment significantly reduced IL-1β, IL-8, RANKL, RANKL/OPG, TOS, OSI, and bone volume ratio levels, and increased TAS levels compared to group P (p < 0.05). High dose colchicine treatment (CH) significantly decreased TUNEL+ cell counts compared to group P (p < 0.05).

CONCLUSIONS

These finding suggest that colchicine has a prophylactic potential for the prevention of periodontal tissue destruction through anti-inflammatory, anti-oxidative, anti-apoptotic, and bone-protective effects.

Predictive factors related to the progression of periodontal disease in patients with early rheumatoid arthritis: a cohort study

Background

Rheumatoid arthritis (RA) and periodontal disease are inter-related conditions. However, factors predictive of periodontal disease progression in patients with early rheumatoid arthritis (eRA) are lacking. The aim of this study was to identify factors associated with the progression of clinical attachment loss (CAL) in interproximal dental sites of eRA patients.

Methods

Twenty-eight eRA patients were evaluated for the progression of CAL at 280 interproximal dental sites at 1 year of follow-up. Markers of RA activity (rheumatoid factor, erythrocyte sedimentation rate, and C-reactive protein), a marker of bone resorption (Dickkopf-related protein 1), Disease Activity Score 28 and Simple Disease Activity Index were included as potential systemic predictive factors. Plaque index, gingival index, pocket depth, clinical attachment level and Dickkopf-related protein 1 in crevicular fluid at baseline were included as potential local predictive factors. Data were analysed in a hierarchical structure using generalised linear mixed models for progression at each site (> 2 mm) during follow-up.

Results

C-reactive protein level was the most important predictive systemic factor for the progression of CAL. The mean CAL and a high degree of gingival inflammation in interproximal sites at baseline were important predictive local factors (p <  0.0001). Patients who received combined treatment with disease-modifying antirheumatic drugs and corticosteroids exhibited less CAL (p <  0.0001). The predictive value of the generalised linear mixed model for progression was 85%.

Conclusions

Systemic factors, including RA disease activity and baseline periodontal condition, were associated with periodontal progression. Pharmacological treatment may affect periodontal progression in patients with early RA.

FoxO1 Overexpression Ameliorates TNF-α-Induced Oxidative Damage and Promotes Osteogenesis of Human Periodontal Ligament Stem Cells via Antioxidant Defense Activation

Periodontitis is a chronic disease that includes the pathologic loss of periodontal tissue and alveolar bone. The inflammatory environment in periodontitis impairs the osteogenic differentiation potential and depresses the regeneration capacity of human periodontal ligament stem cells (hPDLSCs). Since Forkhead box protein O1 (FoxO1) plays an important role in redox balance and bone formation, we investigated the role of FoxO1 in oxidative stress resistance and osteogenic differentiation in an inflammatory environment by overexpressing FoxO1 in hPDLSCs. First, we found that FoxO1 overexpression reduced reactive oxygen species (ROS) accumulation, decreased malondialdehyde (MDA) levels, and elevated antioxidant potential under oxidative condition. Next, the overexpression of FoxO1 protected hPDLSCs against oxidative damage, which involved stabilization of the mitochondrial membrane potential. Third, overexpressed FoxO1 promoted extracellular matrix (ECM) mineralization and increased the expression of the osteogenic markers Runx2 and SP7 in the inflammatory environment. These results indicated that FoxO1 overexpression in hPDLSCs has an anti-inflammatory effect, increases antioxidative capacity, and positively regulates osteogenesis in a mimicked inflammatory environment.

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

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

Fermented Oyster Extract Prevents Ovariectomy-Induced Bone Loss and Suppresses Osteoclastogenesis

There is growing interest in bioactive substances from marine organisms for their potential use against diverse human diseases. Osteoporosis is a skeletal disorder associated with bone loss primarily occurring through enhanced osteoclast differentiation and resorption. Recently, we reported the anti-osteoclastogenic activity of fermented Pacific oyster (Crassostrea gigas) extract (FO) in vitro. The present study focused on investigating the anti-osteoporotic efficacy of FO in bone loss prevention in an experimental animal model of osteoporosis and elucidating the mechanism underlying its effects. Oral administration of FO significantly decreased ovariectomy-induced osteoclast formation and prevented bone loss, with reduced serum levels of bone turnover biomarkers including osteocalcin and C-terminal telopeptide fragment of type I collagen C-terminus (CTX). FO significantly suppressed receptor activator of nuclear factor-κB ligand (RANKL)-induced differentiation of bone marrow-derived macrophages (BMMs) into osteoclasts and attenuated the induction of osteoclast-specific genes required for osteoclastogenesis and bone resorption. Furthermore, FO inhibited RANKL-mediated IκBα and p65 phosphorylation in BMMs. Taken together, these results demonstrate that FO effectively suppresses osteoclastogenesis in vivo and in vitro, and that FO can be considered as a potential therapeutic option for the treatment of osteoporosis and osteoclast-mediated skeletal diseases.

Progranulin Promotes Regeneration of Inflammatory Periodontal Bone Defect in Rats via Anti-inflammation, Osteoclastogenic Inhibition, and Osteogenic Promotion

Progranulin (PGRN) has been proved to play a crucial role in anti-inflammation and osteogenesis promotion; thus, it was hypothesized that PGRN could promote bone regeneration in periodontal disease. In this experiment, the periodontal bone defects were established in periodontitis rats; recombinant human progranulin (rhPGRN), tumor necrosis factor alpha inhibitor (anti-TNF-α), or phosphate buffer saline (PBS)-loaded collagen membrane scaffolds were implanted within defects and the rats were sacrificed at scheduled time points. Volume of new bone was assessed by radiological and histomorphometric analyses. Expression of osteogenesis-related markers and tumor necrosis factor-α (TNF-α) was evaluated using immunohistochemistry. Tartrate-resistant acid phosphatase (TRAP) staining was also performed to determine the number of osteoclasts. Immunofluorescence (IF) staining was performed to explore the interaction between rhPGRN and tumor necrosis factor receptors (TNFRs). The results showed that the rhPGRN group had significantly superior quantity and quality of newly formed bone, higher expression of alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), and TNFR2 compared with the PBS group and the anti-TNF-α group. Similarly to the anti-TNF-α group, the rhPGRN group also exhibited the significant inhibitory effect on the expression of TNF-α and the number of TRAP-positive cells compared with the PBS group. Hence, our experiment suggests that PGRN promotes regeneration of inflammatory periodontal bone defect in rats via anti-inflammation, osteoclastogenic inhibition, and osteogenic promotion. Local administration of PGRN may provide a new therapeutic strategy for periodontal bone regeneration.

Epidemiologic evaluation of Nhanes for environmental Factors and periodontal disease

Periodontitis is a chronic inflammation that destroys periodontal tissues caused by the accumulation of bacterial biofilms that can be affected by environmental factors. This report describes an association study to evaluate the relationship of environmental factors to the expression of periodontitis using the National Health and Nutrition Examination Study (NHANES) from 1999–2004. A wide range of environmental variables (156) were assessed in patients categorized for periodontitis (n = 8884). Multiple statistical approaches were used to explore this dataset and identify environmental variable patterns that enhanced or lowered the prevalence of periodontitis. Our findings indicate an array of environmental variables were different in periodontitis in smokers, former smokers, or non-smokers, with a subset of specific environmental variables identified in each population subset. Discriminating environmental factors included blood levels of lead, phthalates, selected nutrients, and PCBs. Importantly, these factors were found to be coupled with more classical risk factors (i.e. age, gender, race/ethnicity) to create a model that indicated an increased disease prevalence of 2–4 fold across the sample population. Targeted environmental factors are statistically associated with the prevalence of periodontitis. Existing evidence suggests that these may contribute to altered gene expression and biologic processes that enhance inflammatory tissue destruction.

Inhibitory Effect of KP-A038 on Osteoclastogenesis and Inflammatory Bone Loss Is Associated With Downregulation of Blimp1

Excessive osteoclastic activity results in pathological bone resorptive diseases, such as osteoporosis, periodontitis, and rheumatoid arthritis. As imidazole-containing compounds possess extensive therapeutic potential for the management of diverse diseases, we synthesized a series of imidazole derivatives and investigated their effects on osteoclast differentiation and function. In the present study, we found that a novel imidazole derivative, KP-A038, suppressed receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclastogenesis and bone-resorbing activity in vitro and attenuated lipopolysaccharide (LPS)-induced bone destruction in vivo. KP-A038 significantly inhibited the induction of nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) and the expression of its target genes, including tartrate-resistant acid phosphatase (Acp5), cathepsin K (Ctsk), dendritic cell-specific transmembrane protein (Dcstamp), and matrix metallopeptidase 9 (Mmp9). KP-A038 upregulated the expression of negative regulators of osteoclast differentiation, such as interferon regulatory factor-8 (Irf8) and B-cell lymphoma 6 (Bcl6). Consistently, KP-A038 downregulated the expression of B lymphocyte-induced maturation protein-1 (Blimp1 encoded by Prdm1), a repressor for Irf8 and Bcl6. Moreover, administration of KP-A038 reduced LPS-induced bone erosion by suppressing osteoclast formation in vivo. Thus, our findings suggest that KP-A038 may serve as an effective therapeutic agent for the treatment and/or prevention of bone loss in pathological bone diseases, including osteoporosis and periodontitis.

Targeting epigenetic mechanisms in periodontal diseases

Epigenetic factors are heritable genome modifications that potentially impact gene transcription, contributing to disease states. Epigenetic marks play an important role in chronic inflammatory conditions, as observed in periodontal diseases, by allowing microbial persistence or by permitting microbial insult to play a role in the so-called 'hit-and-run' infectious mechanism, leading to lasting pathogen interference with the host genome. Epigenetics also affects the health sciences by providing a dynamic mechanistic framework to explain the way in which environmental and behavioral factors interact with the genome to alter disease risk. In this article we review current knowledge of epigenome regulation in light of the multifactorial nature of periodontal diseases. We discuss epigenetic tagging in identified genes, and consider the potential implications of epigenetic changes on host-microbiome dynamics in chronic inflammatory states and in response to environmental stressors. The most recent advances in genomic technologies have placed us in a position to analyze interaction effects (eg, between periodontal disease and type 2 diabetes mellitus), which can be investigated through epigenome-wide association analysis. Finally, because of the individualized traits of epigenetic biomarkers, pharmacoepigenomic perspectives are also considered as potentially novel therapeutic approaches for improving periodontal disease status.

Serum Nutrient Levels and Aging Effects on Periodontitis

Periodontal disease damages tissues as a result of dysregulated host responses against the chronic bacterial biofilm insult and approximately 50% of US adults >30 years old exhibit periodontitis. The association of five blood nutrients and periodontitis were evaluated due to our previous findings regarding a potential protective effect for these nutrients in periodontal disease derived from the US population sampled as part of the National Health and Nutrition Examination Survey (1999⁻2004). Data from over 15,000 subjects was analyzed for blood levels of cis-β-carotene, β-cryptoxanthin, folate, vitamin D, and vitamin E, linked with analysis of the presence and severity of periodontitis. Moderate/severe disease patients had lower cis-β-carotene levels across all racial/ethnic groups and these decreased levels in moderate/severe periodontitis were exacerbated with age. β-cryptoxanthin demonstrated lower levels in severe disease patients across the entire age range in all racial/ethnic groups. Folate differences were evident across the various age groups with consistently lower levels in periodontitis patients >30 years and most pronounced in females. Lower levels of vitamin D were consistently noted across the entire age range of patients with a greater difference seen in females with periodontitis. Finally, an analytical approach to identify interactions among these nutrients related to age and periodontitis showed interactions of vitamin D in females, and folate with race in the population. These findings suggest that improving specific nutrient intake leading to elevated blood levels of a combination of these protective factors may provide a novel strategy to affect the significant increase in periodontitis that occurs with aging.