Osteoimmunology in Periodontitis: Local Proteins and Compounds to Alleviate Periodontitis

Lockd Enhances Mandibular Mesenchymal Stem Cell Proliferation While Inhibiting Osteogenic Capability via Binding With SUZ12 in the Inflammatory Microenvironment

AIM

To investigate the role of lncRNA Lockd in mandibular mesenchymal stem cell (M-MSC) proliferation and osteogenic capability in the inflammatory microenvironment, focusing on its interaction with SUZ12.

MATERIALS AND METHODS

Using lncR Lockd knockdown/overexpression cell models and a murine periodontitis model, we explored Lockd's effects on M-MSC proliferation and osteogenic capability in the inflammatory microenvironment. Predictions from multiple databases and a series of rescue experiments revealed the regulatory role of the Lockd/SUZ12 signalling axis of M-MSC in the inflammatory microenvironment.

RESULTS

Lockd was found to stimulate M-MSC proliferation but impair osteogenic differentiation. The in vitro studies suggested that the activation of Lockd negatively inhibited the osteogenic differentiation process and may ultimately impact bone formation in periodontitis. Mechanistically, it was elucidated that Lockd interacts with SUZ12, a core component of the polycomb repressive complex 2 (PRC2), and may affect the PRC2 complex's role in osteogenic gene expression.

CONCLUSIONS

Lockd boosts the proliferation of M-MSCs but inhibits their osteogenic differentiation by interacting with SUZ12, potentially inhibiting osteogenic capability in the inflammatory microenvironment.

Inhibition of fibulin-3 ameliorates periodontal inflammation through reducing M1 macrophage polarization via EGFR/PI3K/AKT pathway

BACKGROUND

This study aimed to evaluate the role of fibulin-3 (FBLN3) in macrophage polarization, its mechanism, and its effect on periodontitis.

METHODS

We conducted studies on periodontitis using both clinical samples and ligature-induced mouse periodontitis model. The inflammatory state was assessed using microcomputed tomography, hematoxylin and eosin staining, immunohistochemical staining, and immunofluorescence staining. In vitro, bone marrow-derived macrophages, and RAW 264.7 macrophages were treated with lipopolysaccharide (LPS) and interleukin (IL)-4 to induce polarization. The role of FBLN3 in macrophage polarization was investigated using overexpression plasmids or siRNAs. Furthermore, local injection of adeno-associated virus was employed to suppress FBLN3 expression in periodontal tissues.

RESULTS

FBLN3 levels were greater in periodontitis tissues. FBLN3 promoted M1 polarization and suppressed M2 polarization in macrophages. The overexpression of FBLN3 promoted M1 polarization via the EGFR/PI3K/AKT signaling pathway, an effect that the epidermal growth factor receptor (EGFR) inhibitor PD153035 reversed. Suppressing FBLN3 expression improved periodontal inflammation and reduced alveolar bone loss in periodontitis.

CONCLUSIONS

FBLN3 suppression can mitigate periodontitis by decreasing the M1 macrophage ratio. FBLN3 regulates M1 macrophage polarization through the EGFR/PI3K/AKT signaling pathway.

PLAIN LANGUAGE SUMMARY

Disruption in the collaboration between extracellular matrix (ECM) and immune system is a significant pathology in periodontitis. Macrophages are a crucial part of the immune system and have unique functions, such as polarization. Fibulin-3, an ECM protein, may play a vital role in this dynamic interplay. Fibulin-3 expression is elevated in periodontitis and is closely related to immune cell function. Inhibiting fibulin-3 can alleviate periodontitis by reducing infiltration of immune cells and M1 macrophage ratio. Furthermore, fibulin-3 promoted macrophage M1 polarization by activating the PI3K/AKT signaling pathway through EGFR binding. Our findings offer a clinically relevant rationale for immune response modulation through fibulin-3.

Anti-Osteoclastogenesis Potential of Cocoa Pod Husk (Theobroma cacao L.) Extract: In Silico and In Vivo Study

Periodontitis is a common chronic inflammatory disease characterized by alveolar bone loss. The high polyphenol content in cocoa pod husk (Theobroma cacao L) has the potential to influence bone metabolism and contribute to the inhibition of bone resorption. The aim of this study was to analyze the anti-osteoclastogenesis potential of cocoa pod husk (Theobroma cacao L.) in both in silico and in vivo study. An analysis of the anti-osteoclastogenesis potential of T. cacao bioactive compounds was conducted using molecular docking simulations. Thirty male Wistar rats (Rattus novergicus) were randomly assigned to control negative groups (placebo gel), control positive groups (2% doxycycline gel), and treatment groups (10% cocoa pod husk (CPH) extract gel), with measurements taken on days 7 and 14. Wistar rats were induced with 0.05 ml of P. gingivalis at a concentration of 2x109 CFU/ml intrasulcularly in the maxillary molar to achieved in periodontitis. The number of osteoclasts was observed by hematoxylin and eosin staining, the level of TNF-α was assessed by enzyme-linked immunosorbent assay, and the expression of RANKL was evaluated by immunohistochemical staining. Data were analyzed using One-way ANOVA to examine the differences between the groups. The in silico study showed that the catechin, epicatechin, quercetin, and procyanidin B2 had a strong binding affinity for TNF-α and RANKL. Administration of 10% CPH reduced the number of osteoclasts (p<0.05), TNF-α level on days 7 and 14 (p<0.05), and RANKL expression on day 7 (p<0.05) in experimental rats with periodontitis. Administering 10% CPH inhibited osteoclastogenesis in the experimental periodontitis rats.

Intraperitoneal Injection of the Porphyromonas gingivalis Outer Membrane Vesicle (OMV) Stimulated Expressions of Neuroinflammatory Markers and Histopathological Changes in the Brains of Adult Zebrafish

Porphyromonas gingivalis is the major pathogenic bacteria found in the subgingival plaque of patients with periodontitis, which leads to neuroinflammation. The bacteria destroy periodontal tissue through virulence factors, which are retained in the bacteria's outer membrane vesicles (OMV). This study aimed to determine the real-time effect of an intraperitoneal injection of P. gingivalis OMV on the production and expression of inflammatory markers and histopathological changes in adult zebrafishes' central nervous systems (CNS). Following the LD50 (21 µg of OMV), the zebrafish were injected intraperitoneally with 18 µg of OMVs, and the control group were injected with normal saline at seven different time points. Brains of experimental zebrafish were dissected at desired time points for colorimetric assays, ELISA, and histology. This study discovered that nitric oxide and PGE2 were significantly increased at 45 min, while IL-1β and IL-6 were expressed at subsequent 12 h and 24 h time points, respectively. Histopathological changes such as blood coagulation, astrocytosis, edema, spongiosis, and necrosis were observed between the 6hour and 24 h time points. The two apoptotic enzymes, caspases 3 and 9, were not expressed at any point. In summary, the OMV-induced neuroinflammatory responses and histopathological changes in adult zebrafish were time-point dependent. This study will enrich our understanding of the mechanism of P. gingivalis OMVs in neuroinflammation in a zebrafish model, most especially the timing of the expression of inflammatory mediators in relation to observable changes in brain tissues.

Protocols for collecting mouse PDL cells and bone marrow cells, differentiation, and data analysis

Periodontal ligament cells (PDLCs) and macrophages in bone marrow cells have been widely used to investigate novel therapeutic agents to treat periodontitis. Here, we present a protocol for collecting primary mouse PDLCs and bone marrow cells. We detail steps for culturing and differentiation for both cell types and review data analysis for in vitro experiments using primary PDLCs and bone marrow cells. This protocol can be used to explore the impact of novel therapeutic agents using in vitro experiments. For complete details on the use and execution of this protocol, please refer to Sirisereephap et al.1.

Advances in the application and mechanism of bioactive peptides in the treatment of inflammation

Inflammation is a normal immune response in organisms, but it often triggers chronic diseases such as colitis and arthritis. Currently, the most widely used anti-inflammatory drugs are non-steroidal anti-inflammatory drugs, albeit they are accompanied by various adverse effects such as hypertension and renal dysfunction. Bioactive peptides (BAPs) provide therapeutic benefits for inflammation and mitigate side effects. Herein, this review focuses on the therapeutic effects of various BAPs on inflammation in different body parts. Emphasis is placed on the immunomodulatory mechanisms of BAPs in treating inflammation, such as regulating the release of inflammatory mediators, modulating MAPK and NF-κB signaling pathways, and reducing oxidative stress reactions for immunomodulation. This review aims to provide a reference for the function, application, and anti-inflammation mechanisms of BAPs.

Jaw osteoporosis: Challenges to oral health and emerging perspectives of treatment

Osteoporosis is a prevalent bone metabolic disease that poses a significant challenge to global human health. Jaw osteoporosis, characterized by microstructural damage of the jaw resulting from various factors, is one of the common manifestations of this condition. Recent studies have demonstrated that jaw osteoporosis has multifaceted effects on oral health and can negatively impact conditions such as periodontitis, oral implantation, orthodontic treatment, and wound healing. However, there are still some limitations in the conventional treatment of osteoporosis. For instance, while bisphosphonates can enhance bone quality, they may also lead to osteonecrosis of the jaw, which poses a potential safety hazard in oral diagnosis and treatment. In recent years, considerable attention has been focused on improving the pathological condition of jaw osteoporosis. Treatment strategies such as gut microbial regulation, extracellular vesicles, molecular targeted therapy, herbal medicine, mechanical stimulation are expected to enhance efficacy and minimize adverse reactions. Therefore, understanding these effects and exploring novel treatments for jaw osteoporosis may provide new insights for oral health maintenance and disease treatment. This article reviews the impact of jaw osteoporosis on oral health and describes the limitations associated with current methods. It also discusses emerging perspectives on treatment, offering a comprehensive overview of the challenges and future directions in managing jaw osteoporosis.

Effects of the DL76 Antagonist/Inverse Agonist of Histamine H3 Receptors on Experimental Periodontitis in Rats: Morphological Studies

BACKGROUND

Periodontitis preceded by gingivitis is the most common form of periodontal disease and occurs due to the interaction of microorganisms present in the complex bacterial aggregates of dental plaque biofilm and their metabolism products with periodontal tissues. Histamine is a heterocyclic biogenic amine acting via four types of receptors. Histamine H3 receptors act as presynaptic auto/heteroreceptors to regulate the release of histamine and other neurotransmitters.

AIM

Since the nervous system is able to regulate the progression of the inflammatory process and bone metabolism, the aim of this study was to investigate the effects of DL76, which acts as an antagonist/inverse agonist of H3 receptors, on the course of experimental periodontitis.

MATERIALS AND METHODS

This study was conducted in 24 mature male Wistar rats weighing 245-360 g, aged 6-8 weeks. A silk ligature was placed on the second maxillary molar of the right maxilla under general anesthesia. From the day of ligating, DL76 and 0.9% NaCl solutions were administered subcutaneously for 28 days in the experimental and control groups, respectively. After the experiment, histopathological, immunohistochemical and radiological examinations were performed.

RESULTS

Ligation led to the development of the inflammatory process with lymphocytic infiltration, increased epithelial RANKL and OPG expression as well as bone resorption. DL76 evoked a reduction in (1) lymphocytic infiltration, (2) RANKL and OPG expression as well as (3) bone resorption since the medians of the mesial and distal interdental spaces in the molars with induced periodontitis were 3.56-fold and 10-fold lower compared to the corresponding values in saline-treated animals with periodontitis.

CONCLUSION

DL76 is able to inhibit the progression of experimental periodontitis in rats, as demonstrated by a reduction in the inflammatory cell infiltration, a decrease in the RANKL/RANK OPG pathway expression and a reduction in the alveolar bone resorption.

Exploring the Potential of Micro-Immunotherapy in the Treatment of Periodontitis

Periodontitis, characterized by the progressive destruction of dental support tissues due to altered immune responses, poses a significant concern for public health. This condition involves intricate interactions between the immune response and oral microbiome, where innate and adaptive immune responses, with their diverse cell populations and inflammatory mediators, play crucial roles in this immunopathology. Indeed, cytokines, chemokines, growth factors, and immune cells perform key functions in tissue remodeling. Focusing on periodontal therapies, our attention turns to micro-immunotherapy (MI), employing low doses (LDs) and ultra-low doses (ULDs) of immunological signaling molecules like cytokines, growth factors, and hormones. Existing studies across various fields lay the groundwork for the application of MI in periodontitis, highlighting its anti-inflammatory and regenerative potential in soft tissue models based on in vitro research. In summary, this review underscores the versatility and potential of MI in managing periodontal health, urging further investigations to solidify its clinical integration. MI supports an innovative approach by modulating immune responses at low doses to address periodontitis.

The role of MIF in periodontitis: A potential pathogenic driver, biomarker, and therapeutic target

OBJECTIVE

Periodontitis is an inflammatory disease that involves an imbalance in the oral microbiota, activation of inflammatory and immune responses, and alveolar bone destruction. Macrophage migration inhibitory factor (MIF) is a versatile cytokine involved in several pathological reactions, including inflammatory processes and bone destruction, both of which are characteristics of periodontitis. While the roles of MIF in cancer and other immune diseases have been extensively characterized, its role in periodontitis remains inconclusive.

RESULTS

In this review, we describe a comprehensive analysis of the potential roles of MIF in periodontitis from the perspective of immune response and bone regulation at the cellular and molecular levels. Moreover, we discuss its potential reliability as a novel diagnostic and therapeutic target for periodontitis.

CONCLUSION

This review can aid dental researchers and clinicians in understanding the current state of MIF-related pathogenesis, diagnosis, and treatment of periodontitis.

The spatial transcriptomic landscape of human gingiva in health and periodontitis

The gingiva is a key oral barrier that protects oral tissues from various stimuli. A loss of gingival tissue homeostasis causes periodontitis, one of the most prevalent inflammatory diseases in humans. The human gingiva exists as a complex cell network comprising specialized structures. To understand the tissue-specific pathophysiology of the gingiva, we applied a recently developed spatial enhanced resolution omics-sequencing (Stereo-seq) technique to obtain a spatial transcriptome (ST) atlas of the gingiva in healthy individuals and periodontitis patients. By utilizing Stereo-seq, we identified the major cell types present in the gingiva, which included epithelial cells, fibroblasts, endothelial cells, and immune cells, as well as subgroups of epithelial cells and immune cells. We further observed that inflammation-related signalling pathways, such as the JAK-STAT and NF-κB signalling pathways, were significantly upregulated in the endothelial cells of the gingiva of periodontitis patients compared with those of healthy individuals. Additionally, we characterized the spatial distribution of periodontitis risk genes in the gingiva and found that the expression of IFI16 was significantly increased in endothelial cells of inflamed gingiva. In conclusion, our Stereo-seq findings may facilitate the development of innovative therapeutic strategies for periodontitis by mapping periodontitis-relevant genes and pathways and effector cells.

Inhibition of PKM2 suppresses osteoclastogenesis and alleviates bone loss in mouse periodontitis

BACKGROUND

Chronic periodontitis triggers an increase in osteoclastogenesis, with glycolysis playing a crucial role in this process. Pyruvate kinase M2 (PKM2) is a critical enzyme involved in glycolysis and pyruvate metabolism. Yet, the precise function of PKM2 in osteoclasts and their formation remains unclear and requires further investigation.

METHODS

Bioinformatics was used to investigate critical biological processes in osteoclastogenesis. In vitro, osteoclastogenesis was analyzed using tartrate-resistant acid phosphatase (TRAP) staining, phalloidin staining, quantitative real‑time PCR (RT-qPCR), and Western blotting. Small interfering RNA (siRNA) of PKM2 and Shikonin, a specific inhibitor of PKM2, were used to verify the role of PKM2 in osteoclastogenesis. The mouse model of periodontitis was used to assess the effect of shikonin on bone loss. Analyses included micro computed tomography, immunohistochemistry, flow cytometry, TRAP staining and HE staining.

RESULTS

Bioinformatic analysis revealed a significant impact of glycolysis and pyruvate metabolism on osteoclastogenesis. Inhibition of PKM2 leads to a significant reduction in osteoclastogenesis. In vitro, co-culture of the heat-killed Porphyromonas gingivalis significantly promoted osteoclastogenesis, concomitant with an increased PKM2 expression in osteoclasts. Shikonin weakened the promoting effect of porphyromonas gingivalis on osteoclastogenesis. In vivo experiments demonstrated that inhibition of PKM2 by shikonin alleviated bone loss induced by periodontitis, suppressed excessive osteoclastogenesis in alveolar bone, and reduced tissue inflammation to some extent.

CONCLUSION

PKM2 inhibition by shikonin, a specific inhibitor of this enzyme, attenuated osteoclastogenesis and bone resorption in periodontitis. Shikonin appears to be a promising therapeutic agent for treating periodontitis.

Quercetin-loaded mesoporous nano-delivery system remodels osteoimmune microenvironment to regenerate alveolar bone in periodontitis via the miR-21a-5p/PDCD4/NF-κB pathway

BACKGROUND

Impaired osteo-/angiogenesis, excessive inflammation, and imbalance of the osteoimmune homeostasis are involved in the pathogenesis of the alveolar bone defect caused by periodontitis. Unfortunately, there is still a lack of ideal therapeutic strategies for periodontitis that can regenerate the alveolar bone while remodeling the osteoimmune microenvironment. Quercetin, as a monomeric flavonoid, has multiple pharmacological activities, such as pro-regenerative, anti-inflammatory, and immunomodulatory effects. Despite its vast spectrum of pharmacological activities, quercetin's clinical application is limited due to its poor water solubility and low bioavailability.

RESULTS

In this study, we fabricated a quercetin-loaded mesoporous bioactive glass (Quercetin/MBG) nano-delivery system with the function of continuously releasing quercetin, which could better promote the bone regeneration and regulate the immune microenvironment in the alveolar bone defect with periodontitis compared to pure MBG treatment. In particular, this nano-delivery system effectively decreased injection frequency of quercetin while yielding favorable therapeutic results. In view of the above excellent therapeutic effects achieved by the sustained release of quercetin, we further investigated its therapeutic mechanisms. Our findings indicated that under the periodontitis microenvironment, the intervention of quercetin could restore the osteo-/angiogenic capacity of periodontal ligament stem cells (PDLSCs), induce immune regulation of macrophages and exert an osteoimmunomodulatory effect. Furthermore, we also found that the above osteoimmunomodulatory effects of quercetin via macrophages could be partially blocked by the overexpression of a key microRNA--miR-21a-5p, which worked through inhibiting the expression of PDCD4 and activating the NF-κB signaling pathway.

CONCLUSION

In summary, our study shows that quercetin-loaded mesoporous nano-delivery system has the potential to be a therapeutic approach for reconstructing alveolar bone defects in periodontitis. Furthermore, it also offers a new perspective for treating alveolar bone defects in periodontitis by inhibiting the expression of miR-21a-5p in macrophages and thereby creating a favorable osteoimmune microenvironment.

The essential role of Mkx in periodontal ligament on the metabolism of alveolar bone and cementum

Introduction

The periodontium is a connective tissue which consists of periodontal ligament, alveolar bone, cementum and gingiva. Periodontal ligament (PDL) is a specialized connective tissue that connects the cementum - coating the surface of the tooth - to the alveolar bone. Mohawk homeobox (Mkx) is a transcription factor that is expressed in PDL, that is known to play a vital role in the development and homeostasis of PDL. A detailed functional analysis of Mkx in the periodontal ligament for alveolar bone and cementum metabolism has not yet been conducted.

Materials and methods

Alveolar bone height, bone mineral density (BMD) and bone volume fractions (Bone volume/Total volume: BV/TV) were measured and analyzed using micro-computed tomography (Micro-CT) and 3DBon on 7-week-old male wild-type (WT) (Mkx+/+) (n = 10) and Mkx-knockout (Mkx-/-) (n = 6) rats. Hematoxylin and Eosin (H&E), tartrate-resistant acid phosphatase (TRAP), alkaline phosphatase (ALP) and Masson Trichrome staining were performed on 5, 6, and 7-week-old Mkx+/+ and Mkx-/- rats. Cementum surface area and the number of TRAP-positive osteoclasts/mm were quantified, measured, and compared for 5,6 and 7-week-old Mkx+/+ and Mkx-/- rats (n = 3 each).

Results

The level of alveolar bone height was significantly higher in Mkx-/- rats than in Mkx+/+ rats. On the other hand, there was significantly less BMD in Mkx-/- alveolar bone. A significant increase in cellular cementum could be observed as early as 5 weeks in Mkx-/- rats when compared with Mkx+/+ rats of the same age. More TRAP-positive osteoclasts were observed in Mkx-/- rats.

Conclusion

Our findings further reveal the essential roles of Mkx in the homeostasis of the periodontal tissue. Mkx was found to contribute to bone and cementum metabolism and may be essential to the prevention of diseases such as periodontitis, and could show potential in regenerative treatments.

The role of the CX3CL1/CX3CR1 axis as potential inflammatory biomarkers in subjects with periodontitis and rheumatoid arthritis: A systematic review

OBJECTIVE

This systematic review aimed to investigate the role of the C-X3-C motif ligand 1/chemokine receptor 1 C-X3-C motif (CX3CL1/CX3CR1) axis in the pathogenesis of periodontitis. Furthermore, as a secondary objective, we determine whether the CX3CL1/CX3CR1 axis could be considered complementary to clinical parameters to distinguish between periodontitis and rheumatoid arthritis (RA) and/or systemically healthy subjects.

METHODS

The protocol used for this review was registered in OSF (10.17605/OSF.IO/KU8FJ). This study was designed following Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines. Records were identified using different search engines (PubMed/MEDLINE, Scopus, Science Direct, and Web of Science) from August 10, 2006, to September 15, 2023. The observational studies on human subjects diagnosed with periodontitis and RA and/or systemically healthy were selected to analyze CX3CL1 and CX3CR1 biomarkers. The methodological validity of the selected articles was assessed using NIH.

RESULTS

Six articles were included. Biological samples (gingival crevicular fluid [GCF], saliva, gingival tissue biopsies, serum) from 379 subjects (n = 275 exposure group and n = 104 control group) were analyzed. Higher CX3CL1 and CX3CR1 chemokine levels were found in subjects with periodontitis and RA compared with periodontal and systemically healthy subjects.

CONCLUSION

Very few studies highlight the role of the CX3CL1/CX3CR1 axis in the pathogenesis of periodontitis; however, increased levels of these chemokines are observed in different biological samples (GCF, gingival tissue, saliva, and serum) from subjects with periodontitis and RA compared with their healthy controls. Future studies should focus on long-term follow-up of subjects and monitoring changes in cytokine levels before and after periodontal therapy to deduce an appropriate interval in health and disease conditions.

The association of aldehyde exposure with the risk of periodontitis: NHANES 2013-2014

OBJECTIVES

Three distinct models were utilized to investigate the combined impacts of serum aldehyde exposure and periodontitis.

MATERIALS AND METHODS

We performed a cross-sectional analysis using data from 525 participants in the 2013-2014 National Health and Nutrition Examination Survey (NHANES). The directed acyclic graphs (DAG) were used to select a minimal sufficient adjustment set of variables (MSAs). To investigate the relationship between aldehydes and periodontitis, we established three models including multiple logistic regression model, restricted cubic spline (RCS) model, and Bayesian kernel machine regression (BKMR) model.

RESULTS

After taking all covariates into account, the multiple logistic regression model revealed that elevated concentrations of isopentanaldehyde and propanaldehyde were strongly associated with periodontitis (isopentanaldehyde: OR: 2.38, 95% CI: 1.34-4.23; propanaldehyde: OR: 1.51, 95% CI: 1.08-2.13). Furthermore, the third tertile concentration of isopentanaldehyde was associated with a 2.04-fold increase in the incidence of periodontitis (95% CI: 1.05-3.95) compared to the first tertile concentration, with a P for trend = 0.04. RCS models showed an "L"-shaped relationship between isopentanaldehyde and periodontitis (P for nonlinear association < 0.01), with inflection point of 0.43 ng/mL. BKMR identified a strong connection between mixed aldehydes and periodontitis, with isopentanaldehyde exhibiting the greatest posterior inclusion probability (PIP) with 0.901 and propanaldehyde exhibiting a PIP with 0.775.

CONCLUSIONS

Isopentanaldehyde and propanaldehyde are positively associated with the risk of periodontitis.

CLINICAL RELEVANCE

Periodontitis may be associated with exposure to mixed aldehyde. This study emphasizes the important role of aldehydes in primary prevention of periodontitis.

TRPC expression in human periodontal ligament cells and the periodontal tissue of periodontitis mice: a preliminary study

BACKGROUND

Transient receptor potential canonical (TRPC) channels are non-selective cationic channels with permeability to Ca2+ and Na+. Despite their importance, there are currently few studies on TRPC in the periodontal ligament (PDL) and bone cells in the dental field. To provide biological information regarding TRPC in PDL cells and periodontal tissue, we evaluated TRPC channels expression in the osteoblast differentiation of PDL cells and periodontitis-induced tissue. Human PDL cells were cultured in osteogenic differentiation media for 28 days, and the expression of Runx2, osteocalcin (OCN), and TRPC1, 3, 4, and 6 was evaluated by real-time PCR. In ligature-induced periodontitis mice, the alveolar bone and osteoid areas, the osteoclast number, and the expression of Runx2, OCN, TRPC3, and TRPC6 was evaluated by H&E staining, TRAP staining, and immunohistochemistry, respectively.

RESULTS

In the PDL cell differentiation group, TRPC6 expression peaked on day 7 and TRPC3 expression generally increased during differentiation. During the 28 days of periodontitis progression, alveolar bone loss and osteoclast numbers increased compared to the control group during the experimental period and the osteoid area increased from day 14. TRPC6 expression in the periodontitis group increased in the PDL area and in the osteoblasts compared to the control group, whereas TRPC3 expression increased only in the PDL area on days 7 and 28.

CONCLUSIONS

These results indicate changes of TRPC3 and TRPC6 expression in PDL cells that were differentiating into osteoblasts and in periodontitis-induced tissue, suggesting the need for research on the role of TRPC in osteoblast differentiation or periodontitis progression.

Fermented Rice Bran Supplementation Inhibits LPS-Induced Osteoclast Formation and Bone Resorption in Mice

Fermented rice bran (FRB) is known to have numerous beneficial bioactivities, amongst which is its anti-inflammatory properties when used as a supplement. To determine its effects, we examined osteoclastogenesis and bone resorption caused by injections of lipopolysaccharide (LPS), using mice with and without FRB supplementation. The results were favorable: those that received FRB showed reduced osteoclast numbers and bone resorption compared to those with the control diet. Notably, receptor activator of NF-κB ligand (RANKL) and tumor necrosis factor-α (TNF-α) mRNA levels were shown to be lower in the LPS-treated animals with FRB supplementation. FRB's inhibitory effect on RANKL- and TNF-α-induced osteoclastogenesis was further confirmed in vitro. In culture, macrophages exhibited decreased TNF-α mRNA levels when treated with FRB extract and LPS versus treatment with LPS alone, but there was no significant change in RANKL levels in osteoblasts. We can conclude that FRB supplementation dampens the effect of LPS-induced osteoclastogenesis and bone resorption by controlling TNF-α expression in macrophages and the direct inhibition of osteoclast formation.

B-Cell-Derived TGF-β1 Inhibits Osteogenesis and Contributes to Bone Loss in Periodontitis

B cells play a vital role in the elimination of periodontal pathogens, the regulation of the immune response, and the induction of tissue destruction. However, the role of B cells in the dysfunction of mesenchymal stem cell (MSC) differentiation to osteoblasts in periodontitis (PD) has been poorly studied. Here we show that the frequency of CD45^-CD105⁺CD73⁺ MSCs in inflamed periodontal tissues is significantly decreased in patients with PD compared with that of healthy controls. CD19⁺ B cells dominate the infiltrated immune cells in periodontal tissues of patients with PD. Besides, B-cell depletion therapy reduces the alveolar bone loss in a ligature-induced murine PD model. B cells from PD mice express a high level of TGF-β1 and inhibit osteoblast differentiation by upregulating p-Smad2/3 expression and downregulating Runx2 expression. The inhibitory effect of PD B cells on osteoblast differentiation is reduced by TGF-β1 neutralization or Smad2/3 inhibitor. Importantly, B-cell-specific knockout of TGF-β1 in PD mice significantly increases the number of CD45^-CD105⁺Sca1⁺ MSCs, ALP-positive osteoblast activity, and alveolar bone volume but decreases TRAP-positive osteoclast activity compared with that from control littermates. Lastly, CD19⁺CD27⁺CD38^- memory B cells dominate the B-cell infiltrates in periodontal tissues from both patients with PD and patients with PD after initial periodontal therapy. Memory B cells in periodontal tissues of patients with PD express a high level of TGF-β1 and inhibit MSC differentiation to osteoblasts. Thus, TGF-β1 produced by B cells may contribute to alveolar bone loss in periodontitis, in part, by suppressing osteoblast activity.

Immune infiltration and diagnostic value of immune-related genes in periodontitis using bioinformatics analysis

BACKGROUND AND OBJECTIVES

Periodontitis, which is a chronic inflammatory periodontal disease resulting in destroyed periodontal tissue, is the leading cause of tooth loss in adults. Many studies have found that inflammatory immune responses are involved in the risk of periodontal tissue damage. Therefore, we analyzed the association between immunity and periodontitis using bioinformatics methods to further understand this disease.

MATERIALS AND METHODS

First, the expression profiles of periodontitis and healthy samples were downloaded from the GEO database, including a training dataset GSE16134 and an external validation dataset GSE10334. Then, differentially expressed genes were identified using the limma package. Subsequently, immune cell infiltration was calculated by using the CIBERSORT algorithm. We further identified genes linking periodontitis and immunity from the ImmPort and DisGeNet databases. In addition, some of them were selected to construct a diagnostic model via a logistic stepwise regression analysis.

RESULTS AND CONCLUSIONS

Two hundred sixty differentially expressed genes were identified and found to be involved in responses to bacterial and immune-related processes. Subsequently, immune cell infiltration analysis demonstrates significant differences in the abundance of most immune cells between periodontitis and healthy samples, especially in plasma cells. These results suggested that immunity doses play a non-negligible role in periodontitis. Twenty-one genes linking periodontitis and immunity were further identified. And nine hub genes of them were identified that may be key genes involved in the development of periodontitis. Gene ontology analyses showed that these genes are involved in response to molecules of bacterial origin, cell chemotaxis, and response to chemokines. In addition, three genes of them were selected to construct a diagnostic model. And its good diagnostic performance was demonstrated by the receiver operating characteristic curves, with an area under the curve of 0.9424 for the training dataset and 0.9244 for the external validation dataset.

Bone and Cartilage Biology

Recent technical and conceptual advances in molecular and cellular biology have dramatically advanced bone and cartilage biology [...]

Biomarkers for the severity of periodontal disease in patients with obstructive sleep apnea:IL-1 β, IL-6, IL-17A, and IL-33

Objective

This study aims to compare the salivary and gingival crevicular fluid (GCF) concentrations of five cytokines: IL-1β, IL-6, IL-17A, IL-33, and Tumor Necrosis Factor-alpha (TNF-α) in patients with OSA and their association with periodontitis.

Methods

Samples of saliva and GCF were obtained from 84 patients classified into four groups according to periodontal and OSA diagnosis: G1(H) healthy patients, G2(P) periodontitis and non-OSA patients, G3(OSA) OSA and non-periodontitis patients, and G4(P-OSA) periodontitis and OSA patients. The cytokines in the samples were quantified using multiplexed bead immunoassays. Data were analyzed with the Kruskal-Wallis test, Dunn's multiple comparisons test, and the Spearman correlation test.

Results

Stage III periodontitis was the highest in patients with severe OSA (69%; p=0.0142). Similar levels of IL-1β and IL-6 in saliva were noted in G2(P) and G4(P-OSA). The IL-6, IL-17A and IL-33 levels were higher in the GCF of G4(P-OSA). There was a significant positive correlation between IL-33 in saliva and stage IV periodontitis in G4(P-OSA) (r _s  = 0.531). The cytokine profile of the patients in G4(P-OSA) with Candida spp. had an increase of the cytokine's levels compared to patients who did not have the yeast.

Conclusions

OSA may increase the risk of developing periodontitis due to increase of IL-1β and IL-6 in saliva and IL-6, IL-17A and IL-33 in GCF that share the activation of the osteoclastogenesis. Those cytokines may be considered as biomarkers of OSA and periodontitis.

A Reciprocal Link between Oral, Gut Microbiota during Periodontitis: The Potential Role of Probiotics in Reducing Dysbiosis-Induced Inflammation

Human body is colonized by a florid microbial community of bacteria, archaea, fungi, protists, helminths, and viruses, known as microbiota, which co-evolves with the host and influences its health through all stages of its life. It is well known that oral microorganisms form highly structurally and functionally organized multi-species biofilms and establish a network of complex mutual inter-species interactions having a primary function in synergy, signaling, or antagonism. This ecological model allows the microorganisms to increase their resistance to antimicrobial agents and settle a balanced microbes-host symbiotic relationship that ensures oral and global health status in humans. The host-associated microbiome is an important factor in human health and disease. Therefore, to develop novel diagnostic, therapeutic, and preventive strategies, microbiome's functions and the reciprocal interactions every microbiome entertains with other microbial communities in the human body are being investigated. This review provides an analysis of the literature about the close connection between the two largest microbial communities in humans: the oral and the gut microbiomes. Furthermore, it focuses on how the alteration of their microbial and functional characteristics can lead to and reciprocally influence the onset of both oral and intestinal microbiome-associated illness, along with the potential role of probiotics in ameliorating inflammation and microbial dysbiosis.

Emerging avenues linking myeloid-derived suppressor cells to periodontal disease

Periodontal disease is one of the most common inflammatory disorders in humans. Gingivitis is the mildest form of periodontal disease and its progression can lead to periodontitis, an inflammatory disease characterized by soft tissue damage that can lead to progressive destruction of the periodontal ligament and alveolar bone. Diverse populations of immune cells are involved in periodontal disease. Myeloid-derived suppressor cells (MDSCs) represent a heterogeneous group of immature myeloid cells derived from hematopoietic precursor cells and exhibit T cell immunosuppressive functions that are thought to be involved in periodontal disease. Therefore, MDSCs have been recently analyzed in the context of this disease. In this review, we discuss the most recent advances in the characterization of the biological aspects, subpopulations, and traffic of MDSCs, as well as their immunosuppressive and osteoclastogenic activity in the context of periodontal disease and in the presence of key periodontal pathogens.