Innate and adaptive immunity of periodontal disease. From etiology to alveolar bone loss

Microbiological and molecular aspects of periodontitis pathogenesis: an infection-induced inflammatory condition

Periodontitis (PD) is the most common oral infectious disease. The primary etiologic cause of the onset and development of PD is dental plaque, which consists of bacterial biofilm domiciled within a complex extracellular mass. In PD patients, there is a progressive breakdown of the periodontal ligament and the alveolar bone. In more advanced stages, tooth loss occurs. The progression of this chronic inflammatory disease involves interactions among numerous microbial pathogens particularly, bacteria, the host's immune factors, and various environmental factors. Due to persistent infection by periodonto-pathogenic bacteria, there is an impairment of both innate and acquired immunity, leading to tissue destruction. Chronic inflammation in PD may be associated with several systemic diseases, including cardiovascular conditions, respiratory issues, diabetes, neurological diseases, cancer, and adverse pregnancy outcomes. Antibiotic treatment is one of the effective strategies for treating PD cases, although the emergence of some resistant strains may limit the effectiveness some antibiotics. In this review study, we discussed the main bacteria in PD, the interaction with the immune response, the pathogenesis of bacteria in PD and antibiotic treatment. We also outlined the emergence of resistance to antibiotics among these pathogens.

Proanthocyanidin B2 alleviates Pg.LPS-induced RAW264.7 cellular inflammation and oxidative stress via PI3K/Akt/NFkB pathway

Periodontitis is a multifactorial chronic inflammatory infectious disease associated with systemic diseases. Proanthocyanidin B2 (PB2), a polyphenol, has been investigated to exhibit antioxidant, anti-inflammatory and anti-cancer pharmacological properties. PB2 has shown good efficacy in treating hepatocellular carcinoma, type 2 diabetes mellitus, and ulcerative colitis. There are few studies on PB2 in treating periodontitis, and the molecular mechanism is unknown. This research focused on the effects of PB2 in Porphyromonas gingivalis-derived lipopolysaccharide (Pg. LPS)-stimulated RAW264.7 cells, as well as the potential mechanisms. CCK-8 assay was used to assess the cytotoxic effects of PB2. qRT-PCR assay and ELISA assay were used to evaluate the expression of inflammatory cytokines. DCFH-DA probe and other assay kits were employed to detect oxidative stress indicators. Western blot was conducted to assess important proteins of the PI3K/Akt/NFκB pathway. The results showed that PB2 downregulated the overproduction of pro-inflammatory mediators IL-1β, IL-6, and TNF-α; reduced the generation of ROS, MDA, and NO; Enhanced the activities of anti-inflammatory factor IL-10 and the total antioxidant capacity; and inhibited the activation of PI3K/Akt/NFκB pathway. In addition, the PI3K agonist 740Y-P was able to partially reverse the effects of PB2. This study indicates that PB2 exhibits significant anti-inflammatory and antioxidant effects in P. gingivalis LPS-stimulated RAW264.7 cells, primarily through the inhibition of the PI3K/Akt/NFκB signaling pathway.

Peripheral blood immune cell levels differ with the stage and grade of periodontitis in systemically healthy individuals

OBJECTIVES

To explore the level of peripheral blood immune cells in patients with different stages and grades of periodontitis.

MATERIALS AND METHODS

A total of 229 periodontitis patients and 36 periodontally healthy patients were included in this cross-sectional study. Individuals with systemic diseases were excluded. A periodontal examination and a complete blood cell examination were performed. The percentages of T and B cells and their subsets were analyzed via flow cytometry. Covariance and logistic regression analyses were conducted, and receiver operating characteristic curve analysis was used to assess the predictive ability of the indicators.

RESULTS

The white blood cell (WBC) count, absolute neutrophil count (ANC), neutrophil percentage (NEU%) and neutrophil-to-lymphocyte ratio (NLR) were greater, but the lymphocyte percentage (LYM%) was lower in the periodontitis group than in the healthy control group. Patients with severe periodontitis (Stage III and IV) presented higher WBC, ANC, NEU% and NLR than those with mild and moderate periodontitis (Stage I and II) did. Area under curve (AUC) of the ANC, NEU% and NLR for the prediction of Stage III/IV periodontitis were 0.750, 0.771, and 0.774, respectively. Compared with Grade A or B periodontitis patients, Grade C periodontitis patients had a significantly lower absolute lymphocyte count (ALC) and LYM% but higher NEU% and NLR in Grade C periodontitis. The AUC of the NLR, LYM% and NEU% for predicting Grade C periodontitis were 0.797, 0.799, and 0.793, respectively. In lymphocytes, the proportions of T and B cells were lower in Grade C periodontitis patients than in Grade A or B group. Similarly, immune regulatory cells, including B10 and Treg cells, also decreased. Conversely, the Th17/Treg ratio was greater. Moreover, the Th17/Treg ratio was most strongly correlated with Grade C periodontitis (r = 0.87), followed by Treg cells(r = -0.70) and B10 cells(r = -0.38).

CONCLUSIONS

ANC, NEU%, NLR and LYM% are closely correlated with periodontitis. ANC, NEU%, and NLR may serve as potential markers for Stage III/IV periodontitis. LYM%, NEU%, and NLR may serve as potential markers for Grade C periodontitis. An increase in the Th17/Treg ratio is a high-risk factor for Grade C periodontitis.

CLINICAL RELEVANCE

Peripheral immune cell levels vary with the stage and grade of periodontitis and can be used to distinguish the grade and stage of periodontitis.

Inhibitory effects of Colocasia antiquorum var. esculenta varnish on inflammation and alveolar bone loss in a rat ligature-induced periodontitis model

We aimed to evaluate whether Colocasia antiquorum var. esculenta (CA) mixed with experimental varnish inhibits inflammation and alveolar bone loss in a rat ligature-induced periodontitis model. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) were tested and cell viability of CA were also evaluated. The varnish mixed with CA (CAV) was applied to ligature site of Sprague-Dawley rats and alveolar bone loss and cytokines were measured. CA exhibited a MIC of 31.3 μg/mL and an MBC of 62.5 μg/mL against Porphyromonas gingivalis, with no cytotoxicity. The CAV group exhibited significantly lower levels of alveolar bone loss than the PC group (p<0.05). The expression of IL-1β, TNF-α, and IL-6 was significantly decreased, while that of Runx2 was significantly increased in the CAV than in the PC group (p<0.05). In conclusion, CAV demonstrated the potential to improve the symptoms of periodontitis.

Eldecalcitol alleviates diabetic periodontitis by regulating macrophage efferocytosis and polarization via SOCE machinery

Diabetes exacerbates the occurrence and severity of periodontitis, the pathogenesis of diabetic periodontitis (DPD) is influenced by the delayed resolution of inflammation. Eldecalcitol (ED-71) has shown promise in preventing bone loss in DPD. We herein aimed to investigate the role of ED-71 in the inflammatory regression phase of DPD and elucidate the underlying mechanisms. Type-2 diabetes was induced by streptozotocin injection in Wistar rats, and to explore the in vivo effect of ED-71 on macrophage efferocytosis, periodontitis was induced by ligation combined with lipopolysaccharide. Alveolar bone destruction was assessed using micro-computed tomography, hematoxylin-eosin, immunohistochemistry, and tartrate-resistant acid phosphatase staining. Immunofluorescence staining and flow cytometry detected neutrophils, apoptotic cells, and macrophage polarization in periodontal tissue. Additionally, flow cytometry, real-time polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay were used to examine macrophage efferocytosis and changes in store-operated calcium entry (SOCE). We found that rats with diabetes exhibited more severe alveolar bone destruction and increased neutrophil aggregates in periodontal tissue. Following the ED-71 administration, alveolar bone loss significantly decreased, and the immune microenvironment of periodontal tissue tended to suppress inflammation. Macrophages stimulated with high glucose experienced disruption of SOCE machinery, leading to the inhibition of efferocytosis in vitro. ED-71 demonstrated the ability to restore macrophage efferocytosis by correcting SOCE, and preventing sustained inflammatory damage to periodontal tissue. In conclusion, diabetes impairs macrophage efferocytosis and M2 polarization in periodontitis rats, resulting in the delayed resolution of inflammation. ED-71 could attenuate alveolar bone loss by mitigating macrophage via SOCE machinery in DPD.

Role of periodontal ligament fibroblasts in periodontitis: pathological mechanisms and therapeutic potential

Periodontal ligament fibroblasts (PDLFs) play a crucial role in the etiology of periodontitis and periodontal tissue regeneration. In healthy periodontal tissues, PDLFs maintain the homeostasis of periodontal soft and hard tissues as well as the local immune microenvironment. PDLFs also have the potential for multidirectional transdifferentiation and are involved in periodontal tissue regeneration. On the other hand, PDLFs can become dysfunctional and acquire an inflammatory phenotype to secret various inflammatory cytokines when affected by pathological factors. These cytokines further trigger immune and inflammatory events, and lead to destruction of periodontal soft and hard tissues as well as damage to the regenerative potential of PDLFs. This review summarizes the physiological functions of PDLFs. Meanwhile, this review also highlights recent insights into the pathological mechanisms driving the development of periodontitis through dysfunctional PDLFs and the negative impact on periodontal tissue regeneration. Additionally, this paper summarizes strategies for targeting PDLFs to treat periodontitis, involving blocking multiple stages of the inflammatory response induced by PDLFs and promoting the multidirectional transdifferentiation of PDLFs. Future research directions are proposed to address important questions that have not yet been answered in this field. This article provides a reference for understanding the important role of PDLFs in the pathological mechanisms of periodontitis and for developing new strategies for targeting PDLFs in periodontitis treatment.

The Role of Macrophage Death in Periodontitis: A Review

Periodontitis, an infectious inflammatory disease influenced by various factors, disrupts the delicate balance between the host microbiota and immunity. The resulting excessive immune response exacerbates the progressive destruction of the supporting periodontal tissue. Macrophages are essential elements of the host innate immune system. They are pivotal components in the periodontal immune microenvironment and actively participate in both physiological and pathological processes of periodontal tissue. When confronted with periodontitis-related irritant factors, macrophages may differentiate to pro- or anti-inflammatory subtypes that affect tissue homeostasis. Additionally, macrophages may die in response to bacterial infections, potentially affecting the severity of periodontitis. This article reviews the typical mechanisms underlying macrophage death and its effects on periodontitis. We describe five forms of macrophage death in periodontitis: apoptosis, pyroptosis, necroptosis, ferroptosis, and ETosis. Our review of macrophage death in the pathophysiology of periodontitis enhances comprehension of the pathogenesis of periodontitis that will be useful for clinical practice. Although our review elucidates the complex mechanisms by which macrophage death and inflammatory pathways perpetuate periodontitis, unresolved issues remain, necessitating further research.

Visualize the time dynamics and research trends of macrophage associated periodontitis research from 2004 to 2023: Bibliometrix analysis

BACKGROUND

Macrophages play an important role in the symptoms and structural progression of periodontitis, and are receiving increasing attention. In recent years, research has shown significant progress in macrophage associated periodontitis. However, there is still lack of comprehensive and methodical bibliometric analysis in this domain. Therefore, this research aims to describe the state of the research and current research hotspots of macrophage associated periodontitis from the perspective of bibliometrics.

METHODS

This study collected and screened a total of 1424 articles on macrophage associated periodontitis retrieved between 2004 and 2023 from Web of Science Core Collection database. Use Citespace (6.1. R6), Bibliometrix-R (4.1.3), VOSviewer (1.6.19), and Graphpad Prism8 software to analyze and plot countries/regions, institutions, journals, authors, literature, and keywords to explore the research hotspots and development trends of macrophage associated periodontitis.

RESULT

After analysis, the amount of macrophage associated periodontitis publications has been rising consistently over time, with China having the most publications (29.32%). 3 countries accounted for 65.57% of the total publications: the United States, China, and Japan, occupying a dominant position in this research field. China publications have the fastest growth rate and played a driving role. The most productive institution is the Sichuan University in China. Journal of Periodontal Research is highly popular in the field of macrophage associated periodontitis, with the highest number of publications. Grenier, Daniel is the most prolific author. Inflammation and Bone Loss in Periodontal Disease are the most cited literature. "Biological pathogenic factors," "immune regulation," "mechanism research," "susceptibility factor research," "pathological processes and molecular correlation," "pathological characteristics," "inflammatory response" are the main keyword groups in this field.

CONCLUSION

This study systematically analyzes and describes the development process, direction, and hotspots of macrophage associated periodontitis using bibliometric methods, providing a reference for future researchers who continue to study macrophage associated periodontitis.

Role of innate host defense proteins in oral cancerogenesis

It is nowadays well accepted that chronic inflammation plays a pivotal role in tumor initiation and progression. Under this aspect, the oral cavity is predestined to examine this connection because periodontitis is a highly prevalent chronic inflammatory disease and oral squamous cell carcinomas are the most common oral malignant lesions. In this review, we describe how particular molecules of the human innate host defense system may participate as molecular links between these two important chronic noncommunicable diseases (NCDs). Specific focus is directed toward antimicrobial polypeptides, such as the cathelicidin LL-37 and human defensins, as well as S100 proteins and alarmins. We report in which way these peptides and proteins are able to initiate and support oral tumorigenesis, showing direct mechanisms by binding to growth-stimulating cell surface receptors and/or indirect effects, for example, inducing tumor-promoting genes. Finally, bacterial challenges with impact on oral cancerogenesis are briefly addressed.

Phosphorylation of Serine 536 of p65(RelA) Downregulates Inflammatory Responses

Nuclear factor-κB (NF-κB) is a transcription factor that regulates the expression of various genes involved in inflammatory diseases and immune responses. Recently, a novel transcriptional regulatory mechanism of NF-κB involving the phosphorylation of serine 536 (534 in mice; S534) of its p65 subunit was reported; however, further research is required to elucidate the physiological role of S534 phosphorylation. Therefore, we generated S534A knock-in (KI) mice, in which the S534 of p65 was substituted with alanine. Similar to the wild-type (WT) mice, S534A KI mice developed normally. After stimulation with tumor necrosis factor α (TNFα), mouse embryonic fibroblasts (MEFs) derived from S534A KI mice exhibited increased target gene expression compared with that in the WT MEFs, which was induced by long-term binding of p65 to DNA. According to comprehensive gene expression analysis after stimulation with TNFα, the expression of genes p65ted to inflammatory and immune responses was increased, and the expression of genes p65ted to lipolysis was decreased in S534A KI MEFs. Analyses of a periodontal disease model established using WT and S534A KI mice revealed that alveolar bone resorption was enhanced in S534A KI mice owing to an increase in the number of osteoclasts, which was not attributed to the differentiation of osteoclast precursor cells but to an increased expression of interleukin-1β and receptor activator of NF-κB ligand in the periodontal tissue. Hence, phosphorylation of S536 negatively regulates inflammatory responses in vitro and in vivo.

Development of Cerium Oxide-Laden GelMA/PCL Scaffolds for Periodontal Tissue Engineering

This study investigated gelatin methacryloyl (GelMA) and polycaprolactone (PCL) blend scaffolds incorporating cerium oxide (CeO) nanoparticles at concentrations of 0%, 5%, and 10% w/w via electrospinning for periodontal tissue engineering. The impact of photocrosslinking on these scaffolds was evaluated by comparing crosslinked (C) and non-crosslinked (NC) versions. Methods included Fourier transform infrared spectroscopy (FTIR) for chemical analysis, scanning electron microscopy (SEM) for fiber morphology/diameters, and assessments of swelling capacity, degradation profile, and biomechanical properties. Biological evaluations with alveolar bone-derived mesenchymal stem cells (aBMSCs) and human gingival fibroblasts (HGFs) encompassed tests for cell viability, mineralized nodule deposition (MND), and collagen production (CP). Statistical analysis was performed using Kruskal-Wallis or ANOVA/post-hoc tests (α = 5%). Results indicate that C scaffolds had larger fiber diameters (~250 nm) compared with NC scaffolds (~150 nm). NC scaffolds exhibited higher swelling capacities than C scaffolds, while both types demonstrated significant mass loss (~50%) after 60 days (p < 0.05). C scaffolds containing CeO showed increased Young's modulus and tensile strength than NC scaffolds. Cells cultured on C scaffolds with 10% CeO exhibited significantly higher metabolic activity (>400%, p < 0.05) after 7 days among all groups. Furthermore, CeO-containing scaffolds promoted enhanced MND by aBMSCs (>120%, p < 0.05) and increased CP in 5% CeO scaffolds for both variants (>180%, p < 0.05). These findings underscore the promising biomechanical properties, biodegradability, cytocompatibility, and enhanced tissue regenerative potential of CeO-loaded GelMA/PCL scaffolds for periodontal applications.

Systemic Factors Affecting Human Beta-Defensins in Oral Cavity

Human beta-defensins are host defense peptides with broad antimicrobial and inflammatory functions. In the oral cavity, these peptides are produced mainly by the keratinocytes of the epithelium; however, fibroblasts, monocytes, and macrophages also contribute to oral human beta-defensin expressions. The resident and immune cells of the oral cavity come into contact with various microbe-associated molecular patterns continuously and simultaneously. The overall antimicrobial cellular response is highly influenced by local and environmental factors. Recent studies have produced evidence showing that not only systemic chronic diseases but also systemic factors like hyperglycemia, pregnancy, the long-term use of certain vitamins, and aging can modulate oral cellular antimicrobial responses against microbial challenges. Therefore, the aim of this narrative review is to discuss the role of systemic factors on oral human beta-defensin expressions.

Polarized M2 macrophages induced by glycosylated nano-hydroxyapatites activate bone regeneration in periodontitis therapy

AIM

To investigate the association between periodontal macrophage polarization states and the alveolar bone levels, and to assess whether glycosylated nano-hydroxyapatites (GHANPs) could improve bone regeneration in periodontitis by inducing macrophage M2 polarization.

MATERIALS AND METHODS

The change of macrophage polarization state in inflammatory periodontal tissues (with bone loss) was examined using clinical gingival samples. The relationship between macrophage phenotype and bone level in periodontal bone loss and repair was evaluated using a mouse periodontitis model. The effect of GHANPs on macrophage polarization was assessed by the in vitro model of lipopolysaccharide (LPS)-stimulated inflammation. The polarization-related markers were detected by immunofluorescence staining, real-time polymerase chain reaction and enzyme-linked immunosorbent assay analysis. The therapeutic effect of GHANPs on alveolar bone loss was explored in experimental periodontitis by histological staining and micro-CT analysis.

RESULTS

A lower macrophage M2/M1 ratio was observed in periodontitis-affected human gingival tissues. The results of animal experiments demonstrated a positive correlation between a lower Arg-1/iNOS ratio and accelerated alveolar bone loss; also, the proportion of Arg-1-positive macrophages increased during bone repair and regeneration. The administration of GHANPs partially restored M2 macrophage polarization after LPS stimulation. GHANPs increased alveolar bone repair and regeneration in experimental periodontitis induced by ligation, potentially related to their macrophage M2 transition regulation.

CONCLUSIONS

The findings of this study indicate that the induction of macrophage M2 polarization can be considered a viable approach for enhancing inflammatory bone repair. Additionally, GHANPs show potential in the clinical treatment of periodontitis.

Activity and levels of TNF-α, IL-6 and IL-8 in saliva of children and young adults with dental caries: a systematic review and meta-analysis

BACKGROUND

Cytokines play an important role in the immunopathogenesis of dental caries. A systematic review and meta-analysis was carried out with the following three objectives: 1)To deepen and discuss through a comprehensive analysis of the literature the effects of dental caries on the activity and levels of TNF-α, IL-6 and IL-8 in saliva of children and young adults, 2)To compare the levels of this cytokines in saliva of the exposure group (moderate-severe dental caries) with the control group (caries-free or mild dental caries), and 3)To determine whether the levels of these cytokines could be used as a complementary clinical diagnostic tool to assess the severity of dental caries.

METHODS

The protocol followed PRISMA and Cochrane guidelines and was registered in the Open Science Framework (OSF): https://doi.org/10.17605/OSF.IO/MF74V . A digital search was performed in PubMed/MEDLINE, Cochrane, Scopus, and Google Schoolar databases from February 15th, 2012, to January 13th, 2024. The methodological validity of the selected studies was assessed using Joanna Briggs Institute (JBI) tool. A meta-analysis was performed using a random-effects model to evaluate the association between dental caries/health, and the concentration of TNF-α, IL-6 and IL-8.

RESULTS

The search strategy provided a total of 126 articles, of which 15 investigations met the inclusion criteria. The total number of patients studied was 1,148, of which 743 represented the case/exposure group, and 405 represented the control group. The age of the patients ranged from 3 to 25 years. IL-6 was the most prevalent cytokine in the saliva of children and young adults with active dental caries. The meta-analysis revealed that there are significant differences between the levels of IL-6 and TNF-α in saliva of children with active dental caries compared to their control groups.

CONCLUSIONS

The findings suggest that IL-6 and TNF-α levels may have potential as complementary biomarkers for assessing dental caries severity. However, further research is needed to validate these findings in larger and more diverse populations before clinical application.

Evaluating the impact of oral hygiene instruction and digital oral health education within cardiac rehabilitation clinics: A protocol for a novel, dual centre, parallel randomised controlled trial

INTRODUCTION

Diseases of the periodontal tissues including gingivitis and periodontitis can affect up to 90% and 50% of the population respectively. These conditions are multifactorial inflammatory conditions involving a dysbiotic biofilm that, if left untreated, can lead to the destruction of the supporting structures of the teeth and have significant systemic implications, specifically on cardiovascular health. The elevation of inflammatory markers, particularly high-sensitive C-reactive protein (hsCRP), are strongly associated with an increased risk of atherosclerosis, a key risk factor for cardiovascular disease (CVD). HsCRP as well as other inflammatory markers can be detected in blood samples as early as 21 days after ceasing toothbrushing, due to the immune response to stagnant oral biofilm. The most effective way to ensure oral biofilm cannot remain on oral tissues, thus preventing periodontitis and reducing inflammatory CVD risk, is with good oral hygiene. The primary aim of this study is to assess whether individualised oral hygiene instruction (OHI) partnered with a digital oral health education (DOHE) package can improve the oral health of patients living with CVD.

METHODS AND ANALYSIS

A total of 165 participants will be recruited from the Westmead and Blacktown Mt Druitt cardiac rehabilitation out-patient clinics into this dual centre, single blind, parallel design, randomised controlled trial. A baseline oral health clinical examination will be completed, followed by a self-report questionnaire before they are randomised in a 1:1:1 ratio into one of 3 arms as follows: individualised OHI partnered with DOHE (Group A), (Group B) DOHE only (Group B), and control/usual care (no oral health education) (Group C). Groups will have their intervention repeated at the 6-week follow-up. After completing the 12-week follow-up, Group B and Group C will receive tailored OHI. Group C will also receive the DOHE package. The primary outcome is the change in approximal plaque index score between baseline and 6-week follow up.

ETHICS AND DISSEMINATION

The study has been approved by the Western Sydney Local Health District Human Ethics Committee 2023/ETH00516. Results will be published in peer-reviewed journals and presented at conferences.

TRIAL REGISTRATION NUMBER

ACTRN12623000449639p ANZCTR: https://www.anzctr.org.au/.

Dementia exacerbates periodontal bone loss in females

BACKGROUND

Periodontitis is a chronic inflammatory disease defined by the pathologic loss of the periodontal ligament and alveolar bone in relation to aging. Although clinical cohort studies reported that periodontitis is significantly elevated in males compared to females, emerging evidence indicates that females with dementia are at a greater risk for periodontitis and decreased alveolar bone.

OBJECTIVE

This study aimed to evaluate whether dementia is a potential sex-dependent risk factor for periodontal bone loss using an experimental model of periodontitis induced in the triple transgenic (3x-Tg) dementia-like mice and clinical samples collected from senior 65 plus age patients with diagnosed dementia.

MATERIALS AND METHODS

We induced periodontitis in dementia-like triple-transgenic (3x-Tg) male and female mice and age-matched wild-type (WT) control mice by ligature placement. Then, alveolar bone loss and osteoclast activity were evaluated using micro-CT and in situ imaging assays. In addition, we performed dental examinations on patients with diagnosed dementia. Finally, dementia-associated Aβ42 and p-Tau (T181) and osteoclastogenic receptor activator of nuclear factor kappa-Β ligand (RANKL) in gingival crevicular fluid (GCF) collected from mice and clinical samples were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Alveolar bone loss and in situ osteoclast activity were significantly elevated in periodontal lesions of 3x-Tg females but not males, compared to wild-type control mice. In addition, we also observed that the probing pocket depth (PPD) was also significantly elevated in female patients with dementia. Using ELISA assay, we observed that females had elevated levels of osteoclastogenic RANKL and dementia-associated Aβ42 and p-Tau (T181) in the GCF collected from experimental periodontitis lesions and clinical samples.

CONCLUSION

Altogether, we demonstrate that females with dementia have an increased risk for periodontal bone loss compared to males.

The Association between Salivary Metabolites and Gingival Bleeding Score in Healthy Subjects: A Pilot Study

Periodontal diseases, including gingivitis and periodontitis, are among the most prevalent diseases in humans. Gingivitis is the mildest form of periodontal disease, characterized by inflammation of the gingiva caused by the accumulation of dental plaque. Salivary diagnostics are becoming increasingly popular due to the variation in saliva composition in response to pathological processes. We used a metabolomics approach to investigate whether a specific saliva metabolic composition could indicate preclinical stage of gingivitis. 1H-NMR spectroscopy was used to obtain the salivary metabolite profiles of 20 healthy subjects. Univariate/multivariate statistical analysis evaluated the whole saliva metabolite composition, and the Full-Mouth Bleeding Score (FMBS) was employed as a classification parameter. Identifying a signature of specific salivary metabolites could distinguish the subjects with high FMBS scores but still within the normal range. This set of metabolites may be due to the enzymatic activities of oral bacteria and be associated with the early stages of gingival inflammation. Although this analysis is to be considered exploratory, it seems feasible to establish an FMBS threshold that distinguishes between the absence and presence of early inflammatory alterations at the salivary level.

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.

Analysis of subgingival microbiota and IL-1β, TNF-α and CX3CL1 levels in gingival crevicular fluid of fixed dental prostheses

Prosthetic biomaterials can affect the composition of the subgingival microbiota and consequently the production of proinflammatory cytokines, causing damage to the periodontium. A total of 40 patients were divided into two groups: 20 with monolithic zirconia (MZ) prostheses and 20 with porcelain fused to metal (PFM) with nickel-chromium (Ni-Cr) alloy prostheses. Subgingival plaque and gingival crevicular fluid samples were taken. The Checkerboard technique for DNA-DNA hybridization and the enzyme-linked immunosorbent assay technique were performed. Teeth with MZ presented a lower percentage of bleeding on probing and tooth mobility compared to teeth with PFM with Ni-Cr alloy. Prosthodontic teeth harbored higher total levels of the 18 bacterial species than non-prosthodontic teeth. There was a higher prevalence of S. gordonii and V. parvula species in PFM with Ni-Cr alloy compared to MZ. There was an increase in IL-1β, TNF-α and CX3CL1 levels in PFM with Ni-Cr alloy compared to MZ. MZ is a candidate biomaterial with fewer negative effects on the periodontium, allowing for longer prostheses longevity in the mouth.

IL-23/IL-17 axis levels in gingival crevicular fluid of subjects with periodontal disease: a systematic review

BACKGROUND

The IL-23/IL-17 axis plays an important role in the immunopathogenesis of periodontal disease. A systematic review was conducted to synthesize all research reporting on the levels of the IL-23/IL-17 axis in gingival crevicular fluid (GCF) from subjects with gingivits, and periodontitis, compared to healthy controls.

METHODS

The protocol followed the PRISMA, and Cochrane guidelines, and was registered with the Open Science Framework (OSF): https://doi.org/10.17605/OSF.IO/7495V . A search was conducted in the electronic databases PubMed/MEDLINE, Scopus, Google Schoolar, and Cochrane from November 15th, 2005, to May 10th, 2023. The quality of the studies was assessed using the JBI tool for cross-sectional studies.

RESULTS

The search strategy provided a total of 2,098 articles, of which 12 investigations met the inclusion criteria. The total number of patients studied was 537, of which 337 represented the case group (subjects with gingivitis, and chronic periodontitis), and 200 represented the control group (periodontally healthy subjects). The ages of the patients ranged from 20 to 50 years, with a mean (SD) of 36,6 ± 4,2, of which 47% were men, and 53% were women. 75% of the investigations collected GCF samples with absorbent paper strips, and analyzed cytokine IL-17 levels individually. In addition, qualitative analysis revealed that there are differences between IL-23/IL-17 axis levels in subjects with chronic periodontitis, gingivitis and healthy controls.

CONCLUSIONS

Thus, IL-23/IL-17 axis levels could be used in the future as a diagnostic tool to distinguish between periodontal diseases.

Bioinformatics analysis reveals the potential common genes and immune characteristics between atrial fibrillation and periodontitis

BACKGROUND AND OBJECTIVE

Atrial fibrillation (AF) and periodontitis, both classified under chronic inflammatory diseases, share common etiologies, including genetic factors and immune pathways. However, the exact mechanisms are still poorly understood. This study aimed to explore the potential common genes and immune characteristics between AF and periodontitis.

METHODS

Gene expression datasets for AF and periodontitis were downloaded from the Gene Expression Omnibus (GEO) database. Differential expression analysis was used to identify common genes in the training set. Functional analyses, including Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, were conducted to elucidate the underlying mechanisms. Hub genes were further screened based on expression levels, receiver operating characteristic (ROC) curves, and least absolute shrinkage and selection operator (LASSO) regression. Then, based on the expression levels and ROC values of the hub genes in the validation set, the target genes were identified. Finally, immune cell infiltration analysis was performed on the AF and periodontitis datasets in the training set using the "CIBERSORT" R package. The relationships between target genes, infiltrating immune cells, and inflammatory factors were also investigated. In addition, AF susceptibility, atrial fibrosis, inflammatory infiltration, and RGS1 protein expression in rat models of periodontitis were assessed through in vivo electrophysiology experiments, Masson's trichrome staining, hematoxylin-eosin staining, immunohistochemistry, and western blotting, respectively.

RESULTS

A total of 21 common genes were identified between AF and periodontitis among the differentially expressed genes. After evaluating gene expression levels, ROC curves, and LASSO analysis, four significant genes between AF and periodontitis were identified, namely regulator of G-protein signaling 1 (RGS1), annexin A6 (ANXA6), solute carrier family 27 member 6 (SLC27A6), and ficolin 1 (FCN1). Further validation confirmed that RGS1 was the optimal shared target gene for AF and periodontitis. Immune cell infiltration analysis revealed that neutrophils and T cells play an important role in the pathogenesis of both diseases. RGS1 showed a significant positive correlation with activated memory CD4 T cells and gamma-delta T cells and a negative correlation with CD8 T cells and regulatory T cells in both training sets. Moreover, RGS1 was positively correlated with classical pro-inflammatory cytokines IL1β and IL6. In periodontitis rat models, AF susceptibility, atrial fibrosis, and inflammatory infiltration were significantly increased, and RGS1 expression in the atrial tissue was upregulated.

CONCLUSION

A common gene between AF and periodontitis, RGS1 appears central in linking the two conditions. Immune and inflammatory responses may underlie the interaction between AF and periodontitis.

Immune dysregulation and macrophage polarization in peri-implantitis

The term "peri-implantitis" (peri-implantitis) refers to an inflammatory lesion of the mucosa surrounding an endosseous implant and a progressive loss of the peri-implant bone that supports the implant. Recently, it has been suggested that the increased sensitivity of implants to infection and the quick elimination of supporting tissue after infection may be caused by a dysregulated peri-implant mucosal immune response. Macrophages are polarized in response to environmental signals and play multiple roles in peri-implantitis. In peri-implantitis lesion samples, recent investigations have discovered a considerable increase in M1 type macrophages, with M1 type macrophages contributing to the pro-inflammatory response brought on by bacteria, whereas M2 type macrophages contribute to inflammation remission and tissue repair. In an effort to better understand the pathogenesis of peri-implantitis and suggest potential immunomodulatory treatments for peri-implantitis in the direction of macrophage polarization patterns, this review summarizes the research findings related to macrophage polarization in peri-implantitis and compares them with periodontitis.

Immune indices and oral health in patients infected with the human immunodeficiency virus

BACKGROUND

The human immunodeficiency virus (HIV) is the causative agent of acquired immunodeficiency syndrome (AIDS). During the incubation period of AIDS, oral manifestations may precede systemic symptoms; therefore, it is vitally important to explore the relationship between HIV and oral health and other indicators. This study aimed to further assess the correlation between demographic risk factors, the dental health of HIV-infected patients, and the correlation of oral health indicators with CD4+ T-cell counts (CTCCs) and HIV viral loads (HIV-VLs).

METHODS

Demographic data on 108 HIV-infected patients were first recorded by questionnaire from March 2016 to November 2018. Patients' dental health and oral lesions were assessed by a dental specialist; in addition, they were tested for CTCCs and HIV-VLs by flow cytometry and NucliSENS EasyQ® HIV-1 virometer. Finally, the links between CTCC, HIV-VL, and the dental health (including oral lesions) of the patients were analyzed.

RESULTS

We found that age, marital status, and body mass index (BMI) were relevant to the patient's dental health (P < 0.05) and that their oral hygiene was relevant to their dental health (P < 0.05). However, HIV-VL was not directly related to periodontal/dental clinical indicators (P > 0.05). We discovered that the oral lesions in HIV-infected patients were related to decreased CTCCs and increased HIV-VLs (P < 0.05).

CONCLUSIONS

We concluded that HIV-infected patients with severely impaired immune function tend to have poor dental health. Moreover, the prevalence of oral lesions was negatively correlated with CTCC and positively correlated with HIV-VL.

Molecular mechanism of curcumin on periodontitis: A pharmacological network study

OBJECTIVE

This study aimed to identify the molecular mechanism of curcumin on periodontitis based on a pharmacological network strategy.

METHODS

The potential therapeutic targets of curcumin and differentially expressed genes in periodontitis were identified. Subsequently, we extracted the molecules in common and analyzed them. A metabolic pathway enrichment and gene ontology analysis were performed and the protein-protein interaction network was inferred. These analyses allowed the identification of key proteins. Finally, a molecular docking of the main key proteins was performed with curcumin.

RESULTS

Our results showed that 55 genes are differentially expressed in periodontitis and are potential targets of curcumin. In addition, we observed that these genes participate in cell motility and immune response and are related to chemokine receptors (CXCRs) and enzymatic activity, such as arachidonate 5-lipoxygenase (ALOX5). We identified six key proteins, IL1B, CXCL8, CD44, MMP2, EGFR, and ITGAM; molecular docking revealed that these six proteins spontaneously bind to curcumin.

CONCLUSION

The results of this study helps us understand the molecular mechanism of curcumin in periodontitis. We propose that curcumin affects proinflammatory cytokines, ALOX5, and cell migration through chemokine receptors and acts on the cell membrane. Additionally, we identified six key proteins that are essential in this mechanism, all of which spontaneously bind to curcumin.

Molecular events in the jaw vascular unit: A traditional review of the mechanisms involved in inflammatory jaw bone diseases

Inflammatory jaw bone diseases are common in stomatology, including periodontitis, peri-implantitis, medication-related osteonecrosis of the jaw, radiation osteomyelitis of the jaw, age-related osteoporosis, and other specific infections. These diseases may lead to tooth loss and maxillofacial deformities, severely affecting patients' quality of life. Over the years, the reconstruction of jaw bone deficiency caused by inflammatory diseases has emerged as a medical and socioeconomic challenge. Therefore, exploring the pathogenesis of inflammatory diseases associated with jaw bones is crucial for improving prognosis and developing new targeted therapies. Accumulating evidence indicates that the integrated bone formation and dysfunction arise from complex interactions among a network of multiple cell types, including osteoblast-associated cells, immune cells, blood vessels, and lymphatic vessels. However, the role of these different cells in the inflammatory process and the 'rules' with which they interact are still not fully understood. Although many investigations have focused on specific pathological processes and molecular events in inflammatory jaw diseases, few articles offer a perspective of integration. Here, we review the changes and mechanisms of various cell types in inflammatory jaw diseases, with the hope of providing insights to drive future research in this field.

Eldecalcitol effectively prevents alveolar bone loss by partially improving Th17/Treg cell balance in diabetes-associated periodontitis

Background: Diabetes-associated periodontitis (DPD) is an inflammatory and destructive disease of periodontal tissues in the diabetic population. The disease is manifested as more severe periodontal destruction and is more difficult to treat when compared with periodontitis (PD). Eldecalcitol (ELD) is a novel active vitamin D3 analog; however, little clinical evidence is available on its role on improving PD and DPD, and its specific mechanisms remain unclear. In this study, we evaluated the preventative effects of ELD toward PD and DPD and explored its underlying molecular mechanisms. Methods: Experimental PD and DPD mouse models were established by ligation combined with lipopolysaccharide (LPS) from Porphyromonas gingivalis injection in C57BL/6J and C57BLKS/J Iar- + Leprdb/+Leprdb (db/db) mice, respectively. Simultaneously, ELD (0.25 μg/kg) was orally administered to mice via an intragastric method. Micro-computed tomography (CT), hematoxylin-eosin (HE) staining, immunohistochemistry (IHC), and tartrate-resistant acid phosphatase (TRAP) staining were used to evaluate alveolar bone alterations in vivo. Flow cytometry, immunofluorescence, and real-time polymerase chain reaction (qRT-PCR) were also used to examine gene expression and probe systemic and local changes in Treg and Th17 cell numbers. Additionally, western blotting and immunofluorescence staining were used to examine changes in STAT3/STAT5 signaling. Results: Micro-CT and HE staining showed that the DPD group had higher alveolar bone loss when compared with the PD group. After applying ELD, alveolar bone loss decreased significantly in both PD and DPD groups, and particularly evident in the DPD group. IHC and TRAP staining also showed that ELD promoted osteoblast activity while inhibiting the number of osteoclasts, and after ELD treatment, the receptor activator of nuclear factor-κB ligand (RANKL) to osteoprotegerin (OPG) ratio decreased. More importantly, this decreasing trend was more obvious in the DPD group. Flow cytometry and qRT-PCR also showed that the systemic Th17/Treg imbalance in PD and DPD groups was partially resolved when animals were supplemented with ELD, while immunofluorescence staining and qRT-PCR data showed the Th17/Treg imbalance was partially resolved in the alveolar bone of both ELD supplemented groups. Western blotting and immunofluorescence staining showed increased p-STAT5 and decreased p-STAT3 levels after ELD application. Conclusion: ELD exerted preventative effects toward PD and DPD by partially rectifying Th17/Treg cell imbalance via STAT3/STAT5 signaling. More importantly, given the severity of DPD, we found ELD was more advantageous in preventing DPD.

miRNA-encapsulated abiotic materials and biovectors for cutaneous and oral wound healing: Biogenesis, mechanisms, and delivery nanocarriers

MicroRNAs (miRNAs) as therapeutic agents have attracted increasing interest in the past decade owing to their significant effectiveness in treating a wide array of ailments. These polymerases II-derived noncoding RNAs act through post-transcriptional controlling of different proteins and their allied pathways. Like other areas of medicine, researchers have utilized miRNAs for managing acute and chronic wounds. The increase in the number of patients suffering from either under-healing or over-healing wound demonstrates the limited efficacy of the current wound healing strategies and dictates the demands for simpler approaches with greater efficacy. Various miRNA can be designed to induce pathway beneficial for wound healing. However, the proper design of miRNA and its delivery system for wound healing applications are still challenging due to their limited stability and intracellular delivery. Therefore, new miRNAs are required to be identified and their delivery strategy needs to be optimized. In this review, we discuss the diverse roles of miRNAs in various stages of wound healing and provide an insight on the most recent findings in the nanotechnology and biomaterials field, which might offer opportunities for the development of new strategies for this chronic condition. We also highlight the advances in biomaterials and delivery systems, emphasizing their challenges and resolutions for miRNA-based wound healing. We further review various biovectors (e.g., adenovirus and lentivirus) and abiotic materials such as organic and inorganic nanomaterials, along with dendrimers and scaffolds, as the delivery systems for miRNA-based wound healing. Finally, challenges and opportunities for translation of miRNA-based strategies into clinical applications are discussed.

Neopterin Levels in Periodontitis and after Nonsurgical Periodontal Therapy: Evaluation of Gingival Crevicular Fluid, Oral Fluid, Serum and Urinary Samples-A Case-Control Study

Periodontitis is a chronic inflammatory disease that leads to the destruction of the tooth-supporting tissues with complex immune response. Neopterin (Np), secreted via activated macrophages, is considered a biomarker of cellular immunity. The aim of this study was to evaluate the impact of periodontitis and nonsurgical periodontal therapy. Np gingival crevicular fluid (GCF), oral fluid, serum and urine levels were compared in subjects with periodontitis before periodontal treatment, three months after and in a healthy control. Np GCF concentrations in the study group after treatment were significantly higher than the control group (p = 0.038). The GCF total amount (amount of substance) was significantly higher in the study group before periodontal treatment than in the control group (p = 0.001) and higher than the levels taken after treatment collection (p = 0.024). The oral fluid Np concentrations in the study group after treatment were significantly increased compared to the before treatment concentrations (p = 0.020). The same trend was observed in the urine samples. Significant correlation was found between the serum and oral fluid Np concentrations (p = 0.001, ρ = 0.40). Our results confirm the impact of cellular immunity and macrophages on periodontitis and on the resolution of periodontal inflammation. The presence of neopterin in oral fluid most likely originates in the serum.

Impact of the host response and osteoblast lineage cells on periodontal disease

Periodontitis involves the loss of connective tissue attachment and alveolar bone. Single cell RNA-seq experiments have provided new insight into how resident cells and infiltrating immune cells function in response to bacterial challenge in periodontal tissues. Periodontal disease is induced by a combined innate and adaptive immune response to bacterial dysbiosis that is initiated by resident cells including epithelial cells and fibroblasts, which recruit immune cells. Chemokines and cytokines stimulate recruitment of osteoclast precursors and osteoclastogenesis in response to TNF, IL-1β, IL-6, IL-17, RANKL and other factors. Inflammation also suppresses coupled bone formation to limit repair of osteolytic lesions. Bone lining cells, osteocytes and periodontal ligament cells play a key role in both processes. The periodontal ligament contains cells that exhibit similarities to tendon cells, osteoblast-lineage cells and mesenchymal stem cells. Bone lining cells consisting of mesenchymal stem cells, osteoprogenitors and osteoblasts are influenced by osteocytes and stimulate formation of osteoclast precursors through MCSF and RANKL, which directly induce osteoclastogenesis. Following bone resorption, factors are released from resorbed bone matrix and by osteoclasts and osteal macrophages that recruit osteoblast precursors to the resorbed bone surface. Osteoblast differentiation and coupled bone formation are regulated by multiple signaling pathways including Wnt, Notch, FGF, IGF-1, BMP, and Hedgehog pathways. Diabetes, cigarette smoking and aging enhance the pathologic processes to increase bone resorption and inhibit coupled bone formation to accelerate bone loss. Other bone pathologies such as rheumatoid arthritis, post-menopausal osteoporosis and bone unloading/disuse also affect osteoblast lineage cells and participate in formation of osteolytic lesions by promoting bone resorption and inhibiting coupled bone formation. Thus, periodontitis involves the activation of an inflammatory response that involves a large number of cells to stimulate bone resorption and limit osseous repair processes.

M101, a therapeutic oxygen carrier derived from Arenicola marina, decreased Porphyromonas gingivalis induced hypoxia and improved periodontal healing

BACKGROUND

P. gingivalis exacerbates tissue hypoxia and worsens periodontal inflammation. This study investigated the effect of a therapeutic oxygen carrier (M101), derived from Arenicola marina, on hypoxia and associated inflammation in the context of periodontitis.

METHODS

The effect of M101 on GLUT-1, GLUT-3, HIF-1α and MMP-9 expression, hypoxia and antioxidant status in oral epithelial cells (EC) exposed to CoCl₂ (1000μM), P. gingivalis (MOI 100) and CoCl₂ + P. gingivalis was evaluated through hypoxia detection fluorescence assay, antioxidant concentration colorimetric assay and RTqPCR. Evaluation of M101 on EC proliferation was evaluated in an in vitro wound assay. In experimental periodontitis, periodontal wound healing and osteoclastic activity were compared among natural wound healing, placebo and gels containing M101 (1 g/L and 2 g/L) groups through histomorphometry and TRAP assay respectively. The expression of HIF-1α, MMP-9 and NFκB in periodontal tissues was also evaluated through immunofluorescence studies.

RESULTS

M101 downregulated GLUT-1, GLUT-3, HIF-1α and MMP-9 levels in EC exposed to CoCl₂ , P. gingivalis and CoCl₂ + P. gingivalis (p < 0.05). Fluorescence and colorimetric analyses confirmed hypoxia reduction and antioxidant capacity improvement in such EC upon M101 treatment. Moreover, M101 improved significantly the in vitro wound closure. In vivo, the attachment level was significantly improved, and osteoclastic activity was reduced in mice treated with M101 gels compared to placebo and natural wound healing groups (p < 0.05). HIF-1α, MMP-9 and NFκB expression in periodontal tissues was reduced in M101 gels treated mice compared to the controls.

CONCLUSION

M101 showed promise in resolving hypoxia and associated inflammation mediated tissue degradation. Its potential in the clinical management of periodontitis must be further investigated. This article is protected by copyright. All rights reserved.

EFFICACY OF CURCUMIN-MEDIATED ANTIBACTERIAL PHOTODYNAMIC THERAPY FOR ORAL ANTISEPSIS: A SYSTEMATIC REVIEW AND NETWORK META-ANALYSIS OF RANDOMIZED CLINICAL TRIALS

BACKGROUND

currently, the presence of oral microorganisms resistant to traditional treatment is increasing, thus search for new modalities of therapies is needed. In this context, antimicrobial photodynamic therapy (aPDT) is an alternative approach for the treatment of resistant or not resistant microorganisms. Therefore, the aim of the present study was to conduct a systematic review and meta-analysis of randomized clinical trials of aPDT for oral antisepsis against oral polymicrobial biofilms.

METHODS

PubMed, Science Direct, Scopus, SciELO, Lilacs, Cochrane Library and Embase databases were searched. In total, five articles were included for qualitative analysis and four articles were used for quantitative analyses. Bias assessment of the eligible articles was made using the RoB 2 criteria. Network meta-analysis was performed using the random-effect model. Subgroup's analysis was also conducted. The groups evaluated were aPDT, exposure to light only and no treatment at all (control group). The quality of evidence was accessed by CINeMA approach.

RESULTS

aPDT mediated by curcumin had significant results in the reducing bacterial load (0.31-0.49 log₁₀ UFC/ I²=0%) when compared with the control group. The included articles were classified as low risk of bias, despite biases detected by allocation and blinding. Moreover, quantitative analysis between aPDT and control group and between light and control group were classified with low risk of confidence rating, while the results from aPDT versus light were classified as moderate risk of confidence rating.

CONCLUSION

aPDT has significant efficacy for oral antisepsis, however more randomized clinical trials will be needed to validate the present results.

Polarized Macrophages in Periodontitis: Characteristics, Function, and Molecular Signaling

Periodontitis (PD) is a common chronic infectious disease. The local inflammatory response in the host may cause the destruction of supporting periodontal tissue. Macrophages play a variety of roles in PD, including regulatory and phagocytosis. Moreover, under the induction of different factors, macrophages polarize and form different functional phenotypes. Among them, M1-type macrophages with proinflammatory functions and M2-type macrophages with anti-inflammatory functions are the most representative, and both of them can regulate the tendency of the immune system to exert proinflammatory or anti-inflammatory functions. M1 and M2 macrophages are involved in the destructive and reparative stages of PD. Due to the complex microenvironment of PD, the dynamic development of PD, and various local mediators, increasing attention has been given to the study of macrophage polarization in PD. This review summarizes the role of macrophage polarization in the development of PD and its research progress.