Revisiting the Page & Schroeder model: the good, the bad and the unknowns in the periodontal host response 40 years later

Impact of Inflammatory Markers and Senescence-Associated Secretory Phenotype in the Gingival Crevicular Fluid on the Outcomes of Periodontal Regeneration

The aim of this study was to test the molecular expression profile (senescence-associated secretory phenotype; SASP) in gingival crevicular fluid (GCF) prior to surgery in relation to the distribution of clinical success of periodontal regeneration. Forty consecutive patients presenting sites with residual probing pocket depth (PPD) ≥ 6 mm and intrabony defects ≥ 3 mm were treated through a minimally invasive surgical technique. Pre-operatively, GCF was sampled for inflammatory biomarker analysis related to SASP [interleukin (IL)-1β, IL-6, and IL-12; matrix-metalloproteinases (MMP)-8 and -9]. Better or worse responders were classified depending on the achievement of a composite outcome measure at 1-year [COM; PPD ≤ 4 mm and clinical attachment gain (CAL) gain ≥ 3 mm]. Correlation analyses and logistic regression models were performed. Periodontal regeneration led to significant improvements in mean clinical and radiographic parameters. Teeth achieving COM presented significantly lower amounts of SASP factors compared with non-successful teeth. Higher CAL gain, PPD reduction, and radiographic bone fill were negatively correlated with IL-1β and MMP-8 and -9 (p < 0.001), while IL-12 showed a direct relationship with CAL gain (p = 0.005) and PPD reduction (p = 0.038). Sites expressing higher SASP expression in the GCF before periodontal regeneration achieved worse clinical and radiographic outcomes.

An update on periodontal inflammation and bone loss

Periodontal disease is a chronic inflammatory condition that affects the supporting structures of the teeth, including the periodontal ligament and alveolar bone. Periodontal disease is due to an immune response that stimulates gingivitis and periodontitis, and its systemic consequences. This immune response is triggered by bacteria and may be modulated by environmental conditions such as smoking or systemic disease. Recent advances in single cell RNA-seq (scRNA-seq) and in vivo animal studies have provided new insight into the immune response triggered by bacteria that causes periodontitis and gingivitis. Dysbiosis, which constitutes a change in the bacterial composition of the microbiome, is a key factor in the initiation and progression of periodontitis. The host immune response to dysbiosis involves the activation of various cell types, including keratinocytes, stromal cells, neutrophils, monocytes/macrophages, dendritic cells and several lymphocyte subsets, which release pro-inflammatory cytokines and chemokines. Periodontal disease has been implicated in contributing to the pathogenesis of several systemic conditions, including diabetes, rheumatoid arthritis, cardiovascular disease and Alzheimer's disease. Understanding the complex interplay between the oral microbiome and the host immune response is critical for the development of new therapeutic strategies for the prevention and treatment of periodontitis and its systemic consequences.

Impaired oral health: a required companion of bacterial aspiration pneumonia

Laryngotracheal aspiration has a widely-held reputation as a primary cause of lower respiratory infections, such as pneumonia, and is a major concern of care providers of the seriously ill orelderly frail patient. Laryngeal mechanical inefficiency resulting in aspiration into the lower respiratory tract, by itself, is not the cause of pneumonia. It is but one of several factors that must be present simultaneously for pneumonia to develop. Aspiration of oral and gastric contentsoccurs often in healthy people of all ages and without significant pulmonary consequences. Inthe seriously ill or elderly frail patient, higher concentrations of pathogens in the contents of theaspirate are the primary catalyst for pulmonary infection development if in an immunocompromised lower respiratory system. The oral cavity is a complex and ever changing eco-environment striving to maintain homogeneity among the numerous microbial communities inhabiting its surfaces. Poor maintenance of these surfaces to prevent infection can result inpathogenic changes to these microbial communities and, with subsequent proliferation, can altermicrobial communities in the tracheal and bronchial passages. Higher bacterial pathogen concentrations mixing with oral secretions, or with foods, when aspirated into an immunecompromised lower respiratory complex, may result in bacterial aspiration pneumonia development, or other respiratory or systemic diseases. A large volume of clinical evidence makes it clear that oral cleaning regimens, when used in caring for ill or frail patients in hospitals and long-term care facilities, drastically reduce the incidence of respiratory infection and death. The purpose of this narrative review is to examine oral health as a required causative companionin bacterial aspiration pneumonia development, and the effectiveness of oral infection control inthe prevention of this disease.

AZGP1 Aggravates Macrophage M1 Polarization and Pyroptosis in Periodontitis

Periodontal tissue destruction in periodontitis is a consequence of the host inflammatory response to periodontal pathogens, which could be aggravated in the presence of type 2 diabetes mellitus (T2DM). Accumulating evidence highlights the intricate involvement of macrophage-mediated inflammation in the pathogenesis of periodontitis under both normal and T2DM conditions. However, the underlying mechanism remains elusive. Alpha-2-glycoprotein 1 (AZGP1), a glycoprotein featuring an MHC-I domain, has been implicated in both inflammation and metabolic disorders. In this study, we found that AZGP1 was primarily colocalized with macrophages in periodontitis tissues. AZGP1 was increased in periodontitis compared with controls, which was further elevated when accompanied by T2DM. Adeno-associated virus-mediated overexpression of Azgp1 in the periodontium significantly enhanced periodontal inflammation and alveolar bone loss, accompanied by elevated M1 macrophages and pyroptosis in murine models of periodontitis and T2DM-associated periodontitis, while Azgp1-/- mice exhibited opposite effects. In primary bone marrow-derived macrophages stimulated by lipopolysaccharide (LPS) or LPS and palmitic acid (PA), overexpression or knockout of Azgp1 markedly upregulated or suppressed, respectively, the expression of macrophage M1 markers and key components of the NLR Family Pyrin Domain Containing 3 (NLRP3)/caspase-1 signaling. Moreover, conditioned medium from Azgp1-overexpressed macrophages under LPS or LPS+PA stimulation induced higher inflammatory activation and lower osteogenic differentiation in human periodontal ligament stem cells (hPDLSCs). Furthermore, elevated M1 polarization and pyroptosis in macrophages and associated detrimental effects on hPDLSCs induced by Azgp1 overexpression could be rescued by NLRP3 or caspase-1 inhibition. Collectively, our study elucidated that AZGP1 could aggravate periodontitis by promoting macrophage M1 polarization and pyroptosis through the NLRP3/casapse-1 pathway, which was accentuated in T2DM-associated periodontitis. This finding deepens the understanding of AZGP1 in the pathogenesis of periodontitis and suggests AZGP1 as a crucial link mediating the adverse effects of diabetes on periodontal inflammation.

Clonal hematopoiesis driven by mutated DNMT3A promotes inflammatory bone loss

Clonal hematopoiesis of indeterminate potential (CHIP) arises from aging-associated acquired mutations in hematopoietic progenitors, which display clonal expansion and produce phenotypically altered leukocytes. We associated CHIP-DNMT3A mutations with a higher prevalence of periodontitis and gingival inflammation among 4,946 community-dwelling adults. To model DNMT3A-driven CHIP, we used mice with the heterozygous loss-of-function mutation R878H, equivalent to the human hotspot mutation R882H. Partial transplantation with Dnmt3aR878H/+ bone marrow (BM) cells resulted in clonal expansion of mutant cells into both myeloid and lymphoid lineages and an elevated abundance of osteoclast precursors in the BM and osteoclastogenic macrophages in the periphery. DNMT3A-driven clonal hematopoiesis in recipient mice promoted naturally occurring periodontitis and aggravated experimentally induced periodontitis and arthritis, associated with enhanced osteoclastogenesis, IL-17-dependent inflammation and neutrophil responses, and impaired regulatory T cell immunosuppressive activity. DNMT3A-driven clonal hematopoiesis and, subsequently, periodontitis were suppressed by rapamycin treatment. DNMT3A-driven CHIP represents a treatable state of maladaptive hematopoiesis promoting inflammatory bone loss.

A multi-platform analysis of human gingival crevicular fluid reveals ferroptosis as a relevant regulated cell death mechanism during the clinical progression of periodontitis

Ferroptosis is implicated in the pathogenesis of numerous chronic-inflammatory diseases, yet its association with progressive periodontitis remains unexplored. To investigate the involvement and significance of ferroptosis in periodontitis progression, we assessed sixteen periodontitis-diagnosed patients. Disease progression was clinically monitored over twelve weeks via weekly clinical evaluations and gingival crevicular fluid (GCF) collection was performed for further analyses. Clinical metrics, proteomic data, in silico methods, and bioinformatics tools were combined to identify protein profiles linked to periodontitis progression and to explore their potential connection with ferroptosis. Subsequent western blot analyses validated key findings. Finally, a single-cell RNA sequencing (scRNA-seq) dataset (GSE164241) for gingival tissues was analyzed to elucidate cellular dynamics during periodontitis progression. Periodontitis progression was identified as occurring at a faster rate than traditionally thought. GCF samples from progressing and non-progressing periodontal sites showed quantitative and qualitatively distinct proteomic profiles. In addition, specific biological processes and molecular functions during progressive periodontitis were revealed and a set of hub proteins, including SNCA, CA1, HBB, SLC4A1, and ANK1 was strongly associated with the clinical progression status of periodontitis. Moreover, we found specific proteins - drivers or suppressors - associated with ferroptosis (SNCA, FTH1, HSPB1, CD44, and GCLC), revealing the co-occurrence of this specific type of regulated cell death during the clinical progression of periodontitis. Additionally, the integration of quantitative proteomic data with scRNA-seq analysis suggested the susceptibility of fibroblasts to ferroptosis. Our analyses reveal proteins and processes linked to ferroptosis for the first time in periodontal patients, which offer new insights into the molecular mechanisms of progressive periodontal disease. These findings may lead to novel diagnostic and therapeutic strategies.

Pyroptotic macrophages induce disruption of glutamate metabolism in periodontal ligament stem cells contributing to their compromised osteogenic potential

Macrophage pyroptosis is of key importance to host defence against pathogen infections and may participate in the progression and recovery of periodontitis. However, the role of pyroptotic macrophages in regulating periodontal ligament stem cells (PDLSCs), the main cell source for periodontium renewal, remains unclear. First, we found that macrophage pyroptosis were enriched in gingiva tissues from periodontitis patients compared with those of healthy people through immunofluorescence. Then the effects of pyroptotic macrophages on the PDLSC osteogenic differentiation were investigated in a conditioned medium (CM)-based coculture system in vitro. CM derived from pyroptotic macrophages inhibited the osteogenic differentiation-related gene and protein levels, ALP activity and mineralized nodule formation of PDLSCs. The osteogenic inhibition of CM was alleviated when pyroptosis was inhibited by VX765. Further, untargeted metabolomics showed that glutamate limitation may be the underlying mechanism. However, exogenous glutamate supplementation aggravated the CM-inhibited osteogenic differentiation of PDLSCs. Moreover, CM increased extracellular glutamate and decreased intracellular glutamate levels of PDLSCs, and enhanced the gene and protein expression levels of system xc - (a cystine/glutamate antiporter). After adding cystine to CM-based incubation, the compromised osteogenic potency of PDLSCs was rescued. Our data suggest that macrophage pyroptosis is related to the inflammatory lesions of periodontitis. Either pharmacological inhibition of macrophage pyroptosis or nutritional supplements to PDLSCs, can rescue the compromised osteogenic potency caused by pyroptotic macrophages.

Activation of receptor-interacting protein 3-mediated necroptosis accelerates periodontitis in mice

OBJECTIVE

To investigate the involvement and role of receptor-interacting protein 3 (RIP3)-mediated necroptosis in periodontitis.

METHODS

A periodontitis murine model was established by oral infection with Porphyromonas gingivalis, and activation of necroptosis pathway was identified by immunohistochemistry. Adeno-associated virus was used to knock down Rip3 and the effect of Rip3 knockdown on periodontal inflammation was examined by Micro-CT, qRT-PCR and histological staining. In vitro, P. gingivalis-LPS was used to infect fibroblast cell line L929 and siRNA was used to knock down Rip3. Necroptosis pathway signalling and inflammation in cells were detected by cell viability and death assay, Western Blot, qRT-PCR and immunofluorescence analysis.

RESULTS

Phosphorylation of RIP3 and mixed lineage kinase domain-like protein (MLKL) was increased in the periodontal ligament of mice infected with P. gingivalis. RIP3 knockdown reduced osteoclastogenesis and inflammatory cytokines in the periodontal area, and alleviated alveolar bone loss in vivo. In vitro, P. gingivalis-LPS-induced RIP3-mediated necroptosis in L929 cells, and knockdown of RIP3 by siRNA decreased the expression of inflammatory cytokines.

CONCLUSION

RIP3-mediated necroptosis is activated in periodontitis and blocking necroptosis alleviates disease progression, indicating that RIP3 may be a potential target for periodontitis treatment.

Investigating the Connection between Chronic Periodontitis and Parkinson's Disease: Findings from a Korean National Cohort Study

Recent research suggests a potential relevance between chronic periodontitis (CP) and Parkinson's disease (PD), raising concerns about comorbid PD among elderly CP patients. However, the epidemiologic basis for this association remains unclear. Employing a nested case-control design, this study explored the association between CP and subsequent PD occurrences in Korean adults, leveraging a validated national population-based dataset covering the period from 2002 to 2019. It included 8794 PD patients and 35,176 matched control individuals, established through propensity score matching for age, sex, residential area, and income. Baseline characteristics were compared using standardized differences, and logistic regression was employed to assess the impact of CP histories on PD likelihood while controlling for covariates. We performed a thorough examination of CP events within both 1-year and 2-year intervals preceding the index date, incorporating subgroup analyses. Our analysis revealed no statistically significant association between CP history and PD development overall. However, subgroup analysis revealed a slightly increased likelihood of PD development among CP individuals with a high disease burden (Charlson Comorbidity Index score ≥ 2). In conclusion, although our study did not find a significant overall association between CP history and PD development, the elevated likelihood of PD in subgroups with high disease burden may suggest that comorbidities influence PD probability among certain CP patients. Considering comorbid conditions in PD screening for some individuals with CP may be also important.

Salivary and serum nitric oxide synthase, macrophage inflammatory protein 1 alpha and macrophage migration inhibitory factor levels in periodontal disease

Objective

Periodontal disease is multifactorial inflammatory disease involving both gingivitis and periodontitis. Inducible nitric oxide synthase (iNOS), macrophage inflammatory protein 1 alpha (MIP-1α) and macrophage migration inhibitory factor (MIF) are mediators contributing to the progression of periodontal diseases with distinct functions. The aim of this study is to evaluate the local and systemic iNOS, MIP-1α and MIF concentrations in patients having periodontal disease with different severities.

Design

The study was conducted on 88 individuals equally divided into four groups; 1) Periodontally Healthy 2) Gingivitis 3) Stage I-II Periodontitis 4) Stage III-IV Periodontitis. Saliva and serum samples were obtained from each individual and then periodontal examinations were performed. Plaque and bleeding on probing indexes, probing depths and clinical attachment levels were measured on each tooth to determine the periodontal status. Concentrations of iNOS, MIP-1α and MIF were measured with enzyme-linked immunosorbent assay.

Results

Patients with stage I-II and stage III-IV periodontitis had more iNOS levels than periodontally healthy people in serum and saliva (p ≤ 0,001 for serum; p < 0,05 for saliva). Stage III-IV periodontitis group had significantly more serum-iNOS levels than that in gingivitis group (p = 0,005). When compared with periodontally healthy individuals, MIP-1α levels in stage III-IV periodontitis patients were measured significantly more in saliva; (p = 0,016) but less in serum (p = 0,006) samples. More serum-MIF concentrations were observed in stage I-II periodontitis groups than that in periodontally healthy individuals (p < 0,05).

Conclusion

Increased salivary and serum iNOS and serum-MIF levels in different stages of periodontitis suggest that these molecules might be involved in periodontal disease pathogenesis. Also, oral microenvironment may stimulate the enhanced MIP-1α concentration in advanced periodontitis cases.

Oral microbiota-host interaction: the chief culprit of alveolar bone resorption

There exists a bidirectional relationship between oral health and general well-being, with an imbalance in oral symbiotic flora posing a threat to overall human health. Disruptions in the commensal flora can lead to oral diseases, while systemic illnesses can also impact the oral cavity, resulting in the development of oral diseases and disorders. Porphyromonas gingivalis and Fusobacterium nucleatum, known as pathogenic bacteria associated with periodontitis, play a crucial role in linking periodontitis to accompanying systemic diseases. In periodontal tissues, these bacteria, along with their virulence factors, can excessively activate the host immune system through local diffusion, lymphatic circulation, and blood transmission. This immune response disruption contributes to an imbalance in osteoimmune mechanisms, alveolar bone resorption, and potential systemic inflammation. To restore local homeostasis, a deeper understanding of microbiota-host interactions and the immune network phenotype in local tissues is imperative. Defining the immune network phenotype in periodontal tissues offers a promising avenue for investigating the complex characteristics of oral plaque biofilms and exploring the potential relationship between periodontitis and associated systemic diseases. This review aims to provide an overview of the mechanisms underlying Porphyromonas gingivalis- and Fusobacterium nucleatum-induced alveolar bone resorption, as well as the immunophenotypes observed in host periodontal tissues during pathological conditions.

The oral microbiome of a family including Papillon-Lefèvre-syndrome patients and clinically healthy members

AIMS

The oral microbiota composition of patients diagnosed with Papillon-Lefèvre-syndrome and treated for several years were compared to those existing in the oral cavity of the clinically healthy family members and a cohort of patients having various stages of chronic periodontitis.

MATERIALS AND METHODS

A family with two sisters affected with severe periodontitis and with the typical skin symptoms of Papillon-Lefèvre-syndrome, and symptomless parents and third sibling were investigated. The Patients received periodontal treatment for several years and their oral microbiome was analysed by amplicon sequencing. Data were evaluated by microbial cluster analysis.

RESULTS

The microbiome of the patients with Papillon-Lefèvre-syndrome was predominated with Aggregatibacter actinomycetemcomitans and associated oral periodontopathogens. Although the clinically healthy family members showed no oral disorder, their microbiome resembled that of subjects having mild periodontitis.

CONCLUSIONS

Predominance of A. actinomycetemcomitans in the subgingival microbiome of patients with Papillon-Lefèvre-syndrome suggests that specific treatment strategies directed against this pathobiont may improve the oral health status of the affected individuals.

TRIAL REGISTRATION

The study was conducted in accordance with the Declaration of Helsinki and the ethical permission has been issued by the Human Investigation Review Board of the University of Szeged, Albert Szent-Györgyi Clinical Centre (Permission No. 63/2017-SZTE). September 19, 2017.  https://u-szeged.hu/klinikaikutatas/rkeb-altal-jovahagyott/rkeb-2017 .

Six-Month Follow-Up of Periodontal Condition in Rheumatoid Arthritis and Ankylosing Spondylitis Arthritis Patients Undergoing Anti-Tumour Necrosis Factor-α Therapy

In our present study, we aimed to assess the effects of anti-TNF therapy on periodontal condition in a mixed cohort of patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Moreover, we wished to determine whether the baseline dental condition of these patients would affect response to biological therapy. A cohort of 24 arthritis patients was consecutively recruited before starting anti-TNFα therapy. After the dropout of six patients, we evaluated the dental status of 18 subjects at baseline and after 6 months of biological therapy. Clinical responder (R) and non-responder (NR) status was determined after 6 months of anti-TNF treatment. Plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing pocket depth (PPD), PPDmax, clinical attachment loss (CAL), and CALmax were determined. During the 6-month treatment period, six patients (3 RA and 3 AS) terminated the study prematurely as they did not respond to treatment (NR). Therefore, 18 patients were included in the full analysis. There were no major differences in PI, BOP, PPD, PPD max, CAL, and CALmax, among R and NR patients. TNF inhibition resulted in increased GI (0.65 ± 0.34 vs. 0.88 ± 0.30; p < 0.05), as well as decreased PPDmax (4 ± 1.94 vs. 2.72 ± 1.36; p < 0.05) and CALmax (5.22 ± 2.56 vs. 2.72 ± 1.36; p < 0.05) after 6 months. Eight patients had incomplete canal fillings or dead pulps and/or apical periodontitis; six in the R and two in the NR group. In our present study, anti-TNF therapy seemed to worsen the extent of gingival inflammation (GI); however our results also do not support the reduction of mean CPD and CAL as reported by others.

Occlusive membranes for guided regeneration of inflamed tissue defects

Guided bone regeneration aided by the application of occlusive membranes is a promising therapy for diverse inflammatory periodontal diseases. Symbiosis, homeostasis between the host microbiome and cells, occurs in the oral environment under normal, but not pathologic, conditions. Here, we develop a symbiotically integrating occlusive membrane by mimicking the tooth enamel growth or multiple nucleation biomineralization processes. We perform human saliva and in vivo canine experiments to confirm that the symbiotically integrating occlusive membrane induces a symbiotic healing environment. Moreover, we show that the membrane exhibits tractability and enzymatic stability, maintaining the healing space during the entire guided bone regeneration therapy period. We apply the symbiotically integrating occlusive membrane to treat inflammatory-challenged cases in vivo, namely, the open and closed healing of canine premolars with severe periodontitis. We find that the membrane promotes symbiosis, prevents negative inflammatory responses, and improves cellular integration. Finally, we show that guided bone regeneration therapy with the symbiotically integrating occlusive membrane achieves fast healing of gingival soft tissue and alveolar bone.

Transcriptional Signatures and Network-Based Approaches Identified Master Regulators Transcription Factors Involved in Experimental Periodontitis Pathogenesis

Periodontitis is a chronic inflammatory disease characterized by the progressive and irreversible destruction of the periodontium. Its aetiopathogenesis lies in the constant challenge of the dysbiotic biofilm, which triggers a deregulated immune response responsible for the disease phenotype. Although the molecular mechanisms underlying periodontitis have been extensively studied, the regulatory mechanisms at the transcriptional level remain unclear. To generate transcriptomic data, we performed RNA shotgun sequencing of the oral mucosa of periodontitis-affected mice. Since genes are not expressed in isolation during pathological processes, we disclose here the complete repertoire of differentially expressed genes (DEG) and co-expressed modules to build Gene Regulatory Networks (GRNs) and identify the Master Transcriptional Regulators of periodontitis. The transcriptional changes revealed 366 protein-coding genes and 42 non-coding genes differentially expressed and enriched in the immune response. Furthermore, we found 13 co-expression modules with different representation degrees and gene expression levels. Our GRN comprises genes from 12 gene clusters, 166 nodes, of which 33 encode Transcription Factors, and 201 connections. Finally, using these strategies, 26 master regulators of periodontitis were identified. In conclusion, combining the transcriptomic analyses with the regulatory network construction represents a powerful and efficient strategy for identifying potential periodontitis-therapeutic targets.

Immunomodulators and Their Applications in Dentistry and Periodontics: A Comprehensive Review

The intricate interplay between the immune system and oral health has revealed opportunities for novel therapeutic interventions in dentistry and periodontics. This review article delves into the pivotal role of immunomodulators in orchestrating immune responses within the oral cavity and their applications in managing various oral and periodontal conditions. The oral environment faces many challenges, from microbial infections to tissue injuries, necessitating a precise immune response for optimal oral health maintenance. Characterized by their ability to modulate immune reactions, immunomodulators emerge as versatile tools for maintaining immune equilibrium. This is a comprehensive overview of the mechanisms through which immunomodulators exert their effects, shedding light on their dual role as regulators of both pro-inflammatory and anti-inflammatory pathways. The diverse applications of immunomodulators within dentistry are explored in depth. Immunomodulators exhibit promising outcomes from managing common oral conditions like gingivitis, periodontitis, and oral ulcers to enhancing the integration of dental implants and promoting wound healing post-surgery. This article highlights the various types of immunomodulatory agents utilized in dental practice, elucidating their mechanisms of action, routes of administration, dosages, and potential side effects.

Chronic Periodontitis and the Potential Likelihood of Gastric Cancer: A Nested Case-Control Study in the Korean Population Utilizing a National Health Sample Cohort

There is limited information regarding the potential association between chronic periodontitis (CP) and gastric cancer, especially in the Korean population. This study aimed to explore this relationship. This nested case-control study analyzed data from 10,174 patients with gastric cancer and 40,696 controls from the Korean National Health Insurance Service-National Sample Cohort using propensity score matching. Standardized differences were used to compare baseline characteristics between study groups. Logistic regression analyses adjusted for confounders were conducted to assess the association between history of CP and gastric cancer occurrence. CP histories and comprehensive subgroup analyses in the 1- and 2-year periods preceding the index date were evaluated. Individuals with a history of CP within the 1-year and 2-year periods showed an increased likelihood of developing gastric cancer. Subgroup analyses consistently supported these findings in male participants aged <65 years and individuals with various income levels or living in residential areas. However, no significant associations were observed among participants aged ≥65 years. In conclusion, CP may be a potential risk factor for gastric cancer development in the Korean population. Regular screening for gastric cancer may be necessary for high-risk individuals, specifically men aged <65 years with a history of CP.

Relationship between circulating senescence-associated secretory phenotype levels and severity of type 2 diabetes-associated periodontitis: A cross-sectional study

BACKGROUND

Senescence-associated secretory phenotype (SASP) has recently been found to drive comorbid diabetes and periodontitis by inducing a chronic, low-degree inflammatory state. Here, we sought to explore the relationship between circulating SASP and the severity of type 2 diabetes-associated periodontitis (DP).

METHODS

Eighty patients (middle-aged periodontitis, M-P group; aged periodontitis, A-P group; M-DP group; and A-DP group; n = 20) provided gingival epithelium, serum, and periodontal clinical parameters. Circulating levels of 12 DP-related SASP factors were analyzed by immunoassay. Correlation between periodontal clinical parameters and circulating SASP levels was analyzed by Spearman's rank correlation coefficient and back propagation artificial neural network (BPNN). Senescence markers (p16, p21, and HMGB1) in gingiva were determined by immunofluorescence assay.

RESULTS

M-DP group had increased serum levels of twelve SASP factors compared with the M-P group (p < 0.5). Serum levels of IL-6, IL-4, and RAGE were higher in the A-DP group than the A-P group (p < 0.5). The circulating concentrations of certain SASP proteins, including IL-1β, IL-4, MMP-8, OPG, RANKL, and RAGE were correlated with the clinical parameters of DP. BPNN showed that serum SASP levels had considerable predictive value for CAL of DP. Additionally, the DP group had higher expressions of p16, p21, and cytoplasmic-HMGB1 in the gingiva than the P group (p < 0.5).

CONCLUSIONS

Significantly enhanced circulating SASP levels and aggravated periodontal destruction were observed in patients with DP. Importantly, a non-negligible association between serum SASP levels and the severity of DP was found.

Osteoclast-Derived Exosomal miR-5134-5p Interferes with Alveolar Bone Homeostasis by Targeting the JAK2/STAT3 Axis

Background

In chronic periodontitis, exosomes transport various informative substances between osteoclasts and osteoblasts in alveolar bone. Herein, we aimed to investigate the effect of exosomal micro-ribonucleic acid (miRNA/miR)-5134-5p derived from osteoclasts on osteoblastic proliferation and differentiation and the development of periodontitis in vivo and in vitro.

Methods

The effects of OC-Exos on the proliferation and differentiation of osteoblasts were identified by Real-time quantitative reverse polymerase chain reaction (qRT-PCR), Western blot(WB), alkaline phosphatase(ALP) staining, etc. Exosomal miRNA expression was analyzed by sequencing. The sites of miRNA action were predicted through TargetScan and tested by double luciferase assay. After transfecting miR-5134-5p mimic/inhibitor into osteoblasts, we measured the proliferation and differentiation of osteoblasts by ALP staining and WB, etc. Furthermore, OC-Exos were injected into the gingival sulcus at the ligation site. Inflammation was observed by Hematoxylin-eosin (H&E) staining, the expression of inflammatory factors were detected by qRT-PCR, the resorption of alveolar bone was observed by Micro CT.

Results

Osteoblastic proliferation and differentiation were negatively regulated by OC-Exos in vitro. miRNA sequencing analysis revealed that miR-5134-5p expression was significantly elevated in OC-Exos, which also increased in osteoblasts following OC-Exo intervention. The dual-luciferase assay revealed that miR-5134-5p and Janus kinase 2 (JAK2) had binding sites. miR-5134-5p-mimics could upregulate miR-5134-5p expression in osteoblasts while downregulating Runt-related transcription factor 2(Runx2), phosphorylated-JAK2 (p-JAK2), and phosphorylated-signal transducer and activator of transcription 3 (p-STAT3) expression and inhibited osteogenic differentiation. However, miR-5134-5p-inhibitor had the opposite effect. In vivo, the OC-Exo group demonstrated morphological disruption of periodontal tissue, massive inflammatory cell infiltration, upregulation of inflammatory factors mRNA expression, a significant decrease in BV/TV, and an increase in the cementoenamel junction and alveolar bone crest distance.

Conclusion

Osteoclast-derived exosomal miR-5134-5p inhibits osteoblastic proliferation and differentiation via the JAK2/STAT3 pathway. OC-Exos exacerbate periodontal tissue inflammation and accelerate alveolar bone resorption in mice with experimental periodontitis.

Downregulation of interleukin 6 signaling might reduce the risk of periodontitis: a drug target Mendelian randomization study

Aim

Interleukin 6 (IL-6) is considered to play a role in the dysbiotic host response in the development of periodontitis. While the inhibition of the IL-6 receptor using monoclonal antibodies is a well-established therapy for some diseases, so far, its potential benefit in patients with periodontitis has not been examined. We tested the association of genetically proxied downregulation of IL-6 signaling with periodontitis to explore whether downregulation of IL-6 signaling could represent a viable treatment target for periodontitis.

Materials and methods

As proxies for IL-6 signaling downregulation, we selected 52 genetic variants in close vicinity of the gene encoding IL-6 receptor that were associated with lower circulating C-reactive protein (CRP) levels in a genome-wide association study (GWAS) of 575 531 participants of European ancestry from the UK Biobank and the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium. Associations with periodontitis were tested with inverse-variance weighted Mendelian randomization in a study of 17 353 cases and 28 210 controls of European descent in the Gene-Lifestyle Interactions in Dental Endpoints (GLIDE) consortium. In addition, the effect of CRP reduction independent of the IL-6 pathway was assessed.

Results

Genetically proxied downregulation of IL-6 signaling was associated with lower odds of periodontitis (odds ratio (OR) = 0.81 per 1-unit decrement in log-CRP levels; 95% confidence interval (CI): [0.66;0.99]; P = 0.0497). Genetically proxied reduction of CRP independent of the IL-6 pathway had a similar effect (OR = 0.81; 95% CI: [0.68; 0.98]; P = 0.0296).

Conclusion

In conclusion, genetically proxied downregulation of IL-6 signaling was associated with lower odds of periodontitis and CRP might be a causal target for the effect of IL-6 on the risk of periodontitis.

Illuminating the oral microbiome and its host interactions: animal models of disease

Periodontitis and caries are driven by complex interactions between the oral microbiome and host factors, i.e. inflammation and dietary sugars, respectively. Animal models have been instrumental in our mechanistic understanding of these oral diseases, although no single model can faithfully reproduce all aspects of a given human disease. This review discusses evidence that the utility of an animal model lies in its capacity to address a specific hypothesis and, therefore, different aspects of a disease can be investigated using distinct and complementary models. As in vitro systems cannot replicate the complexity of in vivo host-microbe interactions and human research is typically correlative, model organisms-their limitations notwithstanding-remain essential in proving causality, identifying therapeutic targets, and evaluating the safety and efficacy of novel treatments. To achieve broader and deeper insights into oral disease pathogenesis, animal model-derived findings can be synthesized with data from in vitro and clinical research. In the absence of better mechanistic alternatives, dismissal of animal models on fidelity issues would impede further progress to understand and treat oral disease.

Impact of Treatment on Host Responses in Young Individuals with Periodontitis

Grade C periodontitis in young individuals is characterized by severe/rapid periodontal destruction, usually early onset, in systemically healthy individuals. An individual's host response, triggered by a dysbiotic subgingival biofilm, has been reported as a contributor to the tissue destruction, although mechanisms of this response and contributions to such disease remain poorly understood. Nonsurgical treatment has resulted in positive clinical responses for both localized (now molar-incisor pattern) and generalized forms of grade C periodontitis, especially when adjunctive systemic antibiotics are used. Nonsurgical treatment may also affect host responses, although mechanisms leading to significant changes in this response remain unclear. Significant effects on inflammatory response to antigens/bacteria have been described posttreatment, but evidence for long-term effects remains limited. Nonsurgical treatment in these individuals may also modulate a variety of host markers in serum/plasma and gingival crevicular fluid along with clinical parameter improvements. The impact of other adjuncts to nonsurgical treatment focusing on controlling exacerbated immunoinflammatory responses needs to be further explored in grade C periodontitis in young individuals. Recent evidence suggests that nonsurgical treatment with adjunctive laser therapy may modulate host and microbial responses in those subjects, at least in the short term. Available evidence, while very heterogeneous (including variations in disease definition and study designs), does not provide clear conclusions on this topic yet provides important insights for future studies. In this review, studies within the past decade evaluating the impact of nonsurgical treatment on systemic/local host responses in young individuals with grade C periodontitis, as well as long-term clinical responses posttreatment, will be critically appraised and discussed.

Development of a classification model and an immune-related network based on ferroptosis in periodontitis

BACKGROUND AND OBJECTIVES

Periodontitis is an immunoinflammatory disease characterized by irreversible periodontal attachment loss and bone destruction. Ferroptosis is a kind of immunogenic cell death that depends on the participation of iron ions and is involved in various inflammatory and immune processes. However, information regarding the relationship between ferroptosis and immunomodulation processes in periodontitis is extremely limited. The purpose of this study was to investigate the correlation between ferroptosis and immune responses in periodontitis.

METHODS

Gene expression profiles of gingivae were collected from the Gene Expression Omnibus data portal. After detecting differentially expressed ferroptosis-related genes (FRGs), we used univariate logistic regression analysis followed by logistic least absolute shrinkage and selection operator (LASSO) regression to establish a ferroptosis-related classification model in an attempt to accurately distinguish periodontitis gingival tissues from healthy samples. The infiltration level of immunocytes in periodontitis was then assessed through single-sample gene-set enrichment analysis. Subsequently, we screened out immune-related genes by weighted correlation network analysis and protein-protein interaction (PPI) analysis and constructed an immune-related network based on FRGs and immune-related genes.

RESULTS

A total of 24 differentially expressed FRGs were detected, and an 8-FRG combined signature constituted the classification model. The established model showed outstanding discriminating ability according to the results of receiver operating characteristic (ROC) curve analysis. In addition, the periodontitis samples had a higher degree of immunocyte infiltration. Activated B cells had the strongest positive correlation while macrophages had a strong negative correlation with certain FRGs, and we found that XBP1, ALOX5 and their interacting genes might be crucial genes in the immune-related network.

CONCLUSIONS

The FRG-based classification model had a satisfactory determination ability, which could bring new insights into the pathogenesis of periodontitis. Those genes in the immune-related network, especially hub genes along with XBP1 and ALOX5, would have the potential to serve as promising targets of immunomodulatory treatments for periodontitis.

Immunomodulatory nanotherapeutic approaches for periodontal tissue regeneration

Periodontitis is an infection-induced inflammatory disease characterized by progressive destruction of tooth supporting tissues, which, if left untreated, can result in tooth loss. The destruction of periodontal tissues is primarily caused by an imbalance between the host immune protection and immune destruction mechanisms. The ultimate goal of periodontal therapy is to eliminate inflammation and promote the repair and regeneration of both hard and soft tissues, so as to restore the physiological structure and function of periodontium. Advancement in nanotechnologies has enabled the development of nanomaterials with immunomodulatory properties for regenerative dentistry. This review discusses the immune mechanisms of the major effector cells in the innate and adaptive immune systems, the physicochemical and biological properties of nanomaterials, and the research advancements in immunomodulatory nanotherapeutic approaches for the management of periodontitis and the regeneration of periodontal tissues. The current challenges, and prospects for future applications of nanomaterials are then discussed so that researchers at the intersections of osteoimmunology, regenerative dentistry and materiobiology will continue to advance the development of nanomaterials for improved periodontal tissue regeneration.

Antibacterial-Anti-Inflammatory-Bone Restoration Procedure Achieved by MIN-Loaded PLGA Microsphere for Efficient Treatment of Periodontitis

The main development process of periodontitis involves periodontal pathogenic bacteria as the initiating factor causing the onset of destructive inflammation, which in turn stimulates the destruction of periodontal tissue. It is difficult to achieve the eradication of periodontitis due to the complex interaction among antibacterial, anti-inflammatory, and bone restoration. Herein, we propose an antibacterial-anti-inflammatory-bone restoration procedural treatment strategy with minocycline (MIN) for the efficient treatment of periodontitis. In brief, MIN was prepared into PLGA microspheres with tunable release behavior using different species of PLGA, respectively. The optimally selected PLGA microspheres (LA:GA with 50:50, 10 kDa, and carboxyl group) had a drug loading of 16.91%, an in vitro release of approximately 30 days, which also had a particle size of approximately 11.8 µm with a smooth appearance and a rounded morphology. The DSC and XRD results showed that the MIN was completely encapsulated in the microspheres as an amorphous state. Cytotoxicity tests demonstrated the safety and biocompatibility of the microspheres (cell viabilities at a concentration of 1-200 μg/mL were greater than 97%), and in vitro bacterial inhibition tests showed that the selected microspheres could achieve effective bacterial inhibition at the initial stage after administration. The favorable anti-inflammatory (low TNF-α and IL-10 levels) and bone restoration effects (BV/TV: 71.8869%; BMD: 0.9782 g/cm³; TB.Th: 0.1366 mm; Tb.N: 6.9318 mm^-1; Tb.Sp: 0.0735 mm) were achieved in a SD rat periodontitis model after administering once a week for four weeks. The MIN-loaded PLGA microspheres were proved to be an efficient and safe treatment for periodontitis by procedural antibacterial, anti-inflammatory, and bone restoration.

Neutrophils in the periodontium: Interactions with pathogens and roles in tissue homeostasis and inflammation

Neutrophils are of key importance in periodontal health and disease. In their absence or when they are functionally defective, as occurs in certain congenital disorders, affected individuals develop severe forms of periodontitis in early age. These observations imply that the presence of immune-competent neutrophils is essential to homeostasis. However, the presence of supernumerary or hyper-responsive neutrophils, either because of systemic priming or innate immune training, leads to imbalanced host-microbe interactions in the periodontium that culminate in dysbiosis and inflammatory tissue breakdown. These disease-provoking imbalanced interactions are further exacerbated by periodontal pathogens capable of subverting neutrophil responses to their microbial community's benefit and the host's detriment. This review attempts a synthesis of these findings for an integrated view of the neutrophils' ambivalent role in periodontal disease and, moreover, discusses how some of these concepts underpin the development of novel therapeutic approaches to treat periodontal disease.

Network pharmacology, molecular docking, and experimental pharmacology explored Ermiao wan protected against periodontitis via the PI3K/AKT and NF-κB/MAPK signal pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Ermiao Wan (EMW), a classic and famous traditional Chinese medicine (TCM)-based herbal formula combined Phellodendron chinense C.K.Schneid. (Cortex Phellodendri Chinsis, CP) and Atractylodes lancea (Thunb.) DC. (Rhizoma Atractylodis, RA) with the weight composition of 1:1, has been used for the treatment of periodontitis in China for a long time. However, its efficacy and mechanism of action are still unclear now.

AIM OF THE STUDY

This study explored the efficacy and pharmaceutical mechanism of action of EMW against periodontitis.

MATERIALS AND METHODS

The efficacy of EMW against periodontitis was evaluated using the ligature-induced periodontitis (LIP) mice, and inflammatory-related factors in gingiva and alveolar bone loss were determined using the qRT-PCR and micro-CT assays. The potential pharmacological mechanisms were predicted by bioinformatics analysis and further confirmed by the qRT-PCR and western blotting assays.

RESULTS

EMW exhibited inhibitory effects on periodontitis in the LIP mice. Bio-informational analysis showed the core compounds (berberine and chlorogenic acid) targeted the key genes (AKT, MAPK1, MAPK14, NF-κB, TNF, IL-2, and IL1B) through regulating the PI3K/AKT and NF-κB/MAPK signal pathways, which were validated using the qRT-PCR and western blotting assays.

CONCLUSIONS

EMW could eliminate alveolar bone loss and inhibit inflammation, thereby preventing the development of periodontitis. The mechanism of action may be achieved by regulating the PI3K/AKT and NF-κB/MAPK signal pathways. Therefore, EMW was a potential therapy for the treatment of periodontitis.

Calotropis procera latex protein reduces inflammation and bone loss in ligature-induced period ontitis in male rats

OBJECTIVE

Calotropis procera latex protein (CpLP) is a popular anti-inflammatory and therefore we aimed to study its effects on inflammatory bone loss.

DESIGN

Male Wistar rats were subjected to a ligature of molars. Groups of rats received intraperitoneally CpLP (0.3 mg/kg, 1 mg/kg, or 3 mg/kg) or saline (0.9% NaCl) one hour before ligature and then daily up to 11 days, compared to naïve. Gingiva was evaluated by myeloperoxidase activity and interleukin-1 beta (IL-1β) expression by ELISA. Bone resorption was evaluated in the region between the cement-enamel junction and the alveolar bone crest. The histology considered alveolar bone resorption and cementum integrity, leukocyte infiltration, and attachment level, followed by immunohistochemistry bone markers between 1^st and 2^nd molars. Systemically, the weight of the body and organs, and a leukogram were performed.

RESULTS

The periodontitis significantly increased myeloperoxidase activity and the IL-1β level. The increased bone resorption was histologically corroborated by periodontal destruction, leukocyte influx, and attachment loss, as well as the increasing receptor activator of the nuclear factor-kappa B ligand (RANKL)/osteoprotegerin (OPG) ratio, and Tartrate-resistant acid phosphatase (TRAP)+ cells when compared to naïve. CpLP significantly reduced myeloperoxidase activity, level of IL-1β, alveolar bone resorption, periodontal destruction, leukocyte influx, and attachment loss. The CpLp also reduced the RANKL/OPG ratio and TRAP+ cells, when compared with the saline group, and did not affect the systemic parameters.

CONCLUSIONS

CpLP exhibited a periodontal protective effect by reducing inflammation and restricting osteoclastic alveolar bone resorption in this rat model.

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.

Cinnamaldehyde modulates host immunoinflammatory responses in rat ligature-induced periodontitis and peripheral blood mononuclear cell models

Cinnamaldehyde is a natural product with anti-inflammatory and immune-modulatory properties, known to regulate host responses to bacterial stimuli. This study aimed to investigate the effects of cinnamaldehyde on ligature-induced periodontitis in rats, and its impact on the modulation of human peripheral blood mononuclear cells (PBMC). Male Wistar rats were assigned into three groups:i) control: no ligature + vehicle; ii) ligature: ligature + vehicle; and iii) ligature + cinnamaldehyde (50 mg/kg); all treatments by daily oral gavage. After 14 days of induced periodontitis, the hemimandibles were collected for bone loss evaluation. The gingival levels of IL-1β, MMP-9 and iNOS mRNA were evaluated. Nitric oxide (NO) was measured in both rat saliva and plasma. PBMC were stimulated with Aggregatibacter actinomycetemcomitans (Aa) in the presence or absence of cinnamaldehyde (5, 20 e 40 µM), and cytokine production was quantified in cell supernatant. Proliferating lymphocytes were taken for flow cytometer reading, while culture supernatants were used for IFN-γ and IL-10 assessment. The ligature group had both increased alveolar bone loss and gingival expression of IL-1β, MMP-9 and iNOS compared to the control group. All parameters were attenuated by cinnamaldehyde treatment. Lower salivary but not plasma NO was detected in the cinnamaldehyde compared to the ligature group. Aa-stimulated PBMCs treated with cinnamaldehyde produced less IL-1β; the compound also attenuated lymphocyte proliferation in a dose-dependent manner, as well as cell IL-10 production. Cinnamaldehyde treatment reduced periodontal bone loss, and downregulated key inflammatory mediators and human PBMC responses, pointing to novel potential therapeutic effects of this compound.

Effect of osteoarthritis on alveolar bone loss in experimental periodontitis in rats

BACKGROUND

There is scarce information about the relationship between periodontal disease and osteoarthritis. This study investigated the effect of surgically induced osteoarthritis on alveolar bone loss in experimental periodontitis in rats.

METHODS

12 rats were divided into test and control groups. On day 1, the animals were anaesthetized, and silk ligatures were ligated around 6 maxillary posterior teeth in each animal from both groups. Surgical induction of osteoarthritis was performed on the left knees in the test group. No knee surgeries were performed in the control group. The ligatures were kept in place for 30 days, at which time the animals were euthanatized, and the maxillae and knee joints were harvested and processed for histological analysis. The alveolar bone loss was assessed using a zoom stereomicroscope.

RESULTS

The knee joint histologic sections of the control group showed normal joint features, whereas in the test group there were substantial changes typical of osteoarthritis, including wide joint spaces, prominent monocytic infiltration of the synovium, invasion of periarticular bone, and decreased chondrocyte density. Comparison of the bone height between the groups showed a significantly higher bone loss in the test than in the control group The marginal mean bone height, adjusted for covariates and the intraclass correlation between sites, was 1.19 and 0.78 mm in the test and control groups, respectively (p < .0001).

CONCLUSIONS

Surgically induced osteoarthritis leads to greater alveolar bone loss in the experimental periodontitis model in rats.

Analysis of Salivary Levels of IL-1β, IL17A, OPG and RANK-L in Periodontitis Using the 2017 Classification of Periodontal Diseases-An Exploratory Observational Study

Periodontitis is a chronic disease with a high overall prevalence. It involves a complex interplay between the immune-inflammatory pathways and biofilm changes, leading to periodontal attachment loss. The aims of this study were (i) to assess whether the salivary IL-1β, IL-17A, RANK-L and OPG levels have the potential to discriminate between the mild and severe periodontitis conditions; and (ii) to enable diagnostic/prognostic actions to differentiate between distinct levels of the disease. The analysis of the clinical parameters and the evaluation of the salivary immunomediators levels by means of a multiplex flow assay revealed a statistically significantly higher level of IL-1β in the periodontitis III/IV patients, as well as a higher level of RANK-L in the periodontitis III/IV and I/II patients, when compared to the healthy controls. Furthermore, the grade C periodontitis patients presented a significantly higher level of RANK-L compared to the grade B and grade A patients. In the grade C patients, IL-1β had a positive correlation with the PPD and CAL indices and RANK_L had a positive correlation with CAL. The evidence emerging from this study associates the salivary IL-1β and RANK-L levels with an advanced stage of periodontitis, stage III/IV, and with grade C, suggesting the possible cooperative action of both in the inflammatory and bone loss events. In addition to IL-1β, RANK-L could be considered a combined diagnostic biomarker for periodontitis.

Pathogenetic aspects of the development of psoriatic arthritis in people with generalized chronic periodontitis

The pathogenetic mechanisms of progression of chronic periodontitis and psoriatic arthritis have common components in immune and inflammatory responses.

The pathogenesis of chronic periodontitis involves interaction of microbial and immunological components. As a chronic immune-mediated inflammatory disease and a consequence of an infectious trigger that originally affects gingival soft tissue, periodontitis is typically characterized by periodontal destruction and damage to adjacent connective tissues. Neutrophils contribute to the development of periodontitis and participate in its progression by recruiting T helper 17 cells and stimulating synthesis of the receptor activator of the nuclear factor kappa-β ligand (RANKL), contributing to bone resorption.

Macrophages as producers of proinflammatory cytokines (interleukin (IL)-1β, IL-6, IL-22, IL-23, tumor necrosis factor (TNF)), free radicals, and matrix metalloproteinases contribute to the chronic course of the disease. Tissue destruction results in generation of reactive oxygen species by neutrophils, which, against the background of a decrease in the antioxidant potential, leads to development of oxidative stress. These processes together lead to tooth mobility, formation of periodontal pockets, and bone resorption.

The key factors in the formation of psoriatic arthritis against the background of periodontitis are overproduction of proinflammatory cytokines in target tissues (skin, joints, gingival microflora) and development of an excessive systemic immune response to the microbiota inhabiting the epithelial and periodontal tissues. A statistically confirmed correlation of the progression of periodontal destruction with the presence of psoriatic arthritis proves the significance of the effects of inflammation as a background for the progression of a comorbidity. Increased IL-17 synthesis plays a crucial role in the development of immune responses of pathological bone remodeling and bone resorption in periodontitis and psoriatic arthritis.

Salivary cortisol, dehydroepiandrosterone, and chromogranin A levels in patients with gingivitis and periodontitis and a novel biomarker for psychological stress

Introduction

This study aimed to investigate the neuroendocrine responses based on cortisol, dehydroepiandrosterone (DHEA), cortisol/DHEA ratio, and chromogranin A levels, which reflect the activity of the hypothalamic-pituitary-adrenal axis, according to the presence or absence of psychological stress in patients with gingivitis and periodontitis compared to that in healthy controls.

Methods

In total, 117 patients (60 women, mean age: 36.29 ± 19.03 years) participated in this case-control study, comprising 32 healthy controls, 49 patients with gingivitis, and 36 patients with periodontitis. We investigated the presence of psychological stress and salivary characteristics, and analyzed the stress-related biomarkers of cortisol, DHEA, cortisol/DHEA ratio, and chromogranin A in the stimulated saliva.

Results

Salivary cortisol and chromogranin A levels increased with the severity of periodontal disease; their levels were the highest in the periodontitis group and were significantly higher in the following descending order: periodontitis, gingivitis, and healthy control groups (all values of p < 0.001). Additionally, the DHEA levels and cortisol/DHEA ratio were higher in the periodontitis group than those in the healthy control group (all values of p < 0.001). A multivariate logistic regression analysis revealed that the factors predicting above-average cortisol levels were periodontitis (odds ratio [OR] = 256.829; p < 0.001), women (OR = 6.365; p = 0.004), and psychological stress (OR = 6.036; p = 0.007); those predicting above-average cortisol/DHEA ratios were periodontitis (OR = 11.436; p < 0.001), psychological stress (OR = 3.977; p = 0.003), and women (OR = 2.890; p = 0.026). Thus, periodontitis and psychological stress were significant and strong predictors of above-average cortisol levels and cortisol/DHEA ratios. In the gingivitis group, salivary cortisol levels (r = 0.381, p = 0.007) and cortisol/DHEA ratios (r = 0.479, p < 0.001) were correlated with the presence of psychological stress. In the periodontitis group, increased cortisol/DHEA ratios (r = 0.412, p = 0.013) and lowered salivary buffer capacities (r = -0.334, p = 0.047) were correlated with the presence of psychological stress.

Conclusion

Periodontitis is a multifactorial disease resulting in inflammatory tissue destruction, which differs from gingivitis and a healthy state. Differences in stress-related neuroendocrine markers were revealed based on the severity of periodontal disease. The biomarkers that could be classified according to disease severity were salivary cortisol and chromogranin A levels. Above-average cortisol levels and cortisol/DHEA ratios are significant predictors of psychological stress in patients with gingivitis and periodontitis.

Contribution of -Omics Technologies in the Study of Porphyromonas gingivalis during Periodontitis Pathogenesis: A Minireview

Periodontitis is a non-communicable chronic inflammatory disease characterized by the progressive and irreversible breakdown of the soft periodontal tissues and resorption of teeth-supporting alveolar bone. The etiology of periodontitis involves dysbiotic shifts in the diversity of microbial communities inhabiting the subgingival crevice, which is dominated by anaerobic Gram-negative bacteria, including Porphyromonas gingivalis. Indeed, P. gingivalis is a keystone pathogen with a repertoire of attributes that allow it to colonize periodontal tissues and influence the metabolism, growth rate, and virulence of other periodontal bacteria. The pathogenic potential of P. gingivalis has been traditionally analyzed using classical biochemical and molecular approaches. However, the arrival of new techniques, such as whole-genome sequencing, metagenomics, metatranscriptomics, proteomics, and metabolomics, allowed the generation of high-throughput data, offering a suitable option for bacterial analysis, allowing a deeper understanding of the pathogenic properties of P. gingivalis and its interaction with the host. In the present review, we revise the use of the different -omics technologies and techniques used to analyze bacteria and discuss their potential in studying the pathogenic potential of P. gingivalis.

Gain a Baby Lose a Tooth-Is There an Association between Periodontitis and Preterm Birth?

Preterm birth serves as one of the leading causes of neonatal mortality worldwide. The underlying mechanisms that contribute to preterm birth are not yet fully understood. However, an association between periodontitis and preterm birth has been proposed. The periodontal status and presence of periodontal pathogens in women with different birth outcomes have been previously examined. However, varying definitions of periodontitis and different microbiological methods make their interpretation challenging. The aim of this case-control study on women with and without preterm birth was to investigate their periodontal status using the current classification system for periodontal diseases. Moreover, differences in the periodontal microbiome of the study participants were investigated. Therefore, we collected data on oral and periodontal parameters in 77 puerperal women divided into two groups based on gestational age at delivery: 33 patients with preterm birth (PTB, <37 weeks) and 44 patients with term birth (TB, >37 weeks). These data included pocket probing depth (PPD), clinical attachment loss (CAL), bleeding on probing (BOP), gingival-bleeding index, DMFT index, and gynecologic and dental history. In addition, their oral microbiome was explored. Median CAL and percentage PPD ≥ 4 mm were significantly higher in the PTB group than in the TB group (p = 0.0128 and p = 0.047, respectively). Birth weight was significantly higher in periodontally healthy women than in those with gingivitis (p = 0.0078) or periodontitis (p = 0.0127). The periodontal microbiome differed significantly between groups. Our results are underlining the possible association between periodontitis and preterm delivery. Women with periodontitis had babies with significantly lower birth weights. The microbiome varied between the groups.

Raman microspectroscopy/micro-optical coherence tomography approach for chairside diagnosis of periodontal diseases: A pilot study

BACKGROUND

Our objective was to develop and test a combined Raman microspectroscopy (RMS) and micro-optical coherence tomography (μOCT) approach for chairside quantification of gingival collagen, DNA, epithelium, and connective tissue. We hypothesized that a high-resolution RMS/μOCT can characterize healthy and inflamed periodontal tissues for diagnosis and disease activity monitoring.

METHODS

A prototype instrument was developed, tested ex vivo on gingival specimens and optimized for in vivo intraoral use. The primary outcome measures were the ratios of oral epithelium to connective tissue thickness (OE:CT) and the amount of DNA to collagen type I (DNA/Col 1), and the thickness of sulcular epithelium (SE). For ex vivo testing, eight subjects with healthy periodontal tissues or with Stage II to IV periodontitis were included in the study and underwent crown-lengthening or periodontal surgical procedures, respectively. Gingival biopsies were scanned by RMS/μOCT and histometric analyses were performed. The proof-of-concept study included OE/CT, DNA/Col 1, and SE assessed in six volunteers with or without signs of gingival inflammation (n = 3/group).

RESULTS

The spatially co-registered RMS spectra revealed opposing changes in the collagen and DNA peaks of inflamed compared with healthy tissues (P <0.05). Combined RMS/μOCT analysis showed that OE/CT, DNA/Col, and SE are significantly different between healthy and inflamed sites (P <0.05). Histological assessments confirmed the differences detected by RMS/μOCT. Qualitative analysis of DNA/Col 1 ratios indicated Col I content as the main distinguishing feature for health and DNA content for periodontitis.

CONCLUSION

Results suggest that combined RMS/μOCT chairside imaging may distinguish between healthy and diseased sites by evaluating marginal periodontal morphological and biochemical features.

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.

Tissue Levels of CD80, CD163 and CD206 and Their Ratios in Periodontal and Peri-Implant Health and Disease

This study aimed to compare tissue levels of CD80 (pro-inflammatory macrophage-related surface marker), CD163, and CD206 (anti-inflammatory macrophage-related surface markers), and their ratios in periodontal and peri-implant health and disease. Altogether, 36 tissue samples were obtained from 36 participants with clinically healthy gingiva (n = 10), healthy peri-implant mucosa (n = 8), periodontitis lesions (n = 9), and peri-implantitis lesions (n = 9). CD80, CD163, and CD206 levels were assessed with immunoblotting. CD163 levels were found to be decreased (p = 0.004), and the CD80/CD163 ratio was found to be elevated (p = 0.002) in periodontitis lesions compared to healthy gingiva. Peri-implantitis lesions showed a tendency towards a higher CD80/CD163 ratio than in healthy peri-implant mucosa with a borderline difference (p = 0.054). No statistically significant difference was detected in CD80, CD163, and CD206 levels of periodontitis lesions when compared to peri-implantitis, and in healthy gingiva when compared to healthy peri-implant mucosa. A disruption in CD80/CD163 balance seems to be related to the pathogenesis of periodontitis and peri-implantitis, being less prominent in the latter. The reason behind this phenomenon may be either suppressed CD163 expression or reduced CD163+ anti-inflammatory macrophage abundance.

Expression of periodontitis susceptibility genes in human gingiva using single-cell RNA sequencing

OBJECTIVE

Single-cell transcriptomics was used to determine the possible cell-type specificity of periodontitis susceptibility genes.

BACKGROUND

The last decade has witnessed remarkable advances in the field of human genomics. Despite many advances, the genetic factors associated with or contributing to the periodontitis pathogenesis have only been identified to a limited extent and are often poorly validated. Confirming whether a given single nucleotide polymorphism has an association with periodontitis requires a robust mechanistic explanation on the functional consequences of a given genetic variant.

METHODS

We globally assessed the expression of 26 disease-associated genes identified by GWAS within the gingival mucosa. A total of 12 411 cells from 4 different donors were analysed. Differentially expressed genes were analysed using Seurat, a non-parametric Wilcoxon rank sum test. The minimum threshold for significance was defined as p < .05.

RESULTS

This exploration at a cellular-level suggests diverse populations contributing to disease pathogenesis, with macrophages expressing a higher number of the analysed disease-associated genes. IL1B, PTGS2, FCGR2A, IL10 and IL1A specifically showed a more restricted expression in the myeloid lineages.

CONCLUSION

This short report combines human genetics and single-cell genomics to better understand periodontitis by mapping variants to predict their cells of action and putative functions. These findings seem to suggest that innate cell dysfunction is linked to disease susceptibility.

Patients with obstructive sleep apnea can favor the predisposing factors of periodontitis by the presence of P. melaninogenica and C. albicans, increasing the severity of the periodontal disease

Objective

The aim of this study was to analyze the cultivable oral microbiota of patients with obstructive sleep apnea (OSA) and its association with the periodontal condition.

Methods

The epidemiology profile of patients and their clinical oral characteristics were determined. The microbiota was collected from saliva, subgingival plaque, and gingival sulcus of 93 patients classified into four groups according to the periodontal and clinical diagnosis: Group 1 (n = 25), healthy patients; Group 2 (n = 17), patients with periodontitis and without OSA; Group 3 (n = 19), patients with OSA and without periodontitis; and Group 4 (n = 32), patients with periodontitis and OSA. Microbiological samples were cultured, classified, characterized macroscopically and microscopically, and identified by MALDI-TOF-MS. The distribution of complexes and categories of microorganisms and correlations were established for inter- and intra-group of patients and statistically evaluated using the Spearman r test (p-value <0.5) and a multidimensional grouping analysis.

Result

There was no evidence between the severity of OSA and periodontitis (p = 0.2813). However, there is a relationship between the stage of periodontitis and OSA (p = 0.0157), with stage III periodontitis being the one with the highest presence in patients with severe OSA (prevalence of 75%; p = 0.0157), with more cases in men. The greatest distribution of the complexes and categories was found in oral samples of patients with periodontitis and OSA (Group 4 P-OSA); even Candida spp. were more prevalent in these patients. Periodontitis and OSA are associated with comorbidities and oral conditions, and the microorganisms of the orange and red complexes participate in this association. The formation of the dysbiotic biofilm was mainly related to the presence of these complexes in association with Candida spp.

Conclusion

Periodontopathogenic bacteria of the orange complex, such as Prevotella melaninogenica, and the yeast Candida albicans, altered the cultivable oral microbiota of patients with periodontitis and OSA in terms of diversity, possibly increasing the severity of periodontal disease. The link between yeasts and periodontopathogenic bacteria could help explain why people with severe OSA have such a high risk of stage III periodontitis. Antimicrobial approaches for treating periodontitis in individuals with OSA could be investigated in vitro using polymicrobial biofilms, according to our findings.

Oral Health in Breast Cancer Women with Vitamin D Deficiency: A Machine Learning Study

Breast cancer (BC) survivors treated with aromatase inhibitors (AIs) commonly show several pathological issues, including poor oral health, bone health impairment, and vitamin D deficiency. However, to date, oral health issues in BC survivors treated with AIs have been poorly investigated and their relationship with vitamin D deficiency are far from being understood. This study aimed to evaluate the correlation between oral health and vitamin D status in BC survivors undergoing treatment with AIs through a machine learning approach. In this cross-sectional study, we included post-menopausal BC women with vitamin D deficiency undergoing AIs therapy. The outcome measures were the following: oral health indexes as the Decayed, Missing, and Filled Permanent Teeth Index (DMFT); serum levels of 25(OH)D₃; Bone Mineral Density (BMD); and the diagnosis of osteoporosis. We included 41 post-menopausal BC women, mean aged 66.10 ± 8.47 years, with mean serum levels of vitamin D of 14.63 ± 6.62 ng/mL. Furthermore, 56.10% of patients had a diagnosis of osteoporosis and 36.59% were osteopenic. DMFT was significantly related to smoking (p-value = 0.005) and dental floss use (p-value = 0.001). There was a significant correlation between DMFT and vitamin D levels (Pearson’s r: −0.73; p-value = 0.001). The regression machine learning model showed that vitamin D status and the use of dental floss were the most relevant variables in terms of correlation with DMFT. In conclusion, vitamin D deficiency, inadequate use of dental floss, and smoking had a negative impact on oral health in BC women. Thus, vitamin D deficiency screening and supplementation and a prompt oral rehabilitation plan should be suggested and implemented in the complex treatment framework of BC survivors undergoing treatment with AIs.

Myeloid-derived growth factor regulates high glucose-mediated apoptosis of gingival fibroblasts and induce AKT pathway activation and nuclear factor κB pathway inhibition

Background

/purpose: Periodontal disease is a chronic inflammatory disease that occurs in the tissues that support and attach teeth. There is considerable evidence of a relationship between diabetes and periodontal disease. Emerging studies have reported that myeloid-derived growth factor (MYDGF) can inhibit apoptosis and inflammation. The purpose of this study was to investigate whether MYDGF mediates the role of hyperglycemia in fibroblasts in periodontitis tissues.

Materials and methods

Fibroblasts were isolated and cultured from normal gums. Gene expression levels were detected by RT-PCR. The protein level was detected by western blotting. Cell viability was determined by MTT assay. To investigate the role of MYDGF, the plasmid was transfected into fibroblasts. The expression levels of cytokines were determined by ELISA.

Results

High glucose can down-regulate the expression of MYDGF in human gingival fibroblasts in a time-dependent manner, and decrease the fibroblast activity. SOD level was decreased and MDA level was increased in gingival fibroblasts by high glucose. High glucose up-regulates pro-apoptotic indicator Bax, down-regulates anti-apototic indicator Bcl-2, and increased endoplasmic reticulum stress related indicators Nox 2, GRP78, ATF6, and PERK. In addition, high glucose increased TNF-α, IL-1β, IL-8 and CXCL1 protein levels in fibroblasts. Our study also found that high glucose inhibits the AKT signaling pathway and activates the nuclear factor κB (NF-κB) pathway. Interestingly, overexpression of MYDGF reversed these effects.

Conclusion

MYDGF is down-regulated in gingival fibroblasts induced by high glucose. Overexpression of MYDGF inhibits apoptosis induced by high glucose, inhibits oxidative stress and cytokine secretion of gingival fibroblasts induced by high glucose, and induces AKT pathway activation and NF-κB pathway inhibition.

Semaphorin 3A protects against alveolar bone loss during orthodontic tooth movement in mice with periodontitis

OBJECTIVE

This study investigated the effect of local semaphorin 3A (Sema3A) administration on alveolar bone loss during OTM in a mouse model of periodontitis.

BACKGROUND

Orthodontic tooth movement (OTM) for patients with periodontal disease is known to increase the risk of exacerbating alveolar bone loss due to inflammation of the periodontal tissue. However, its mechanism of action and prevention remains unclear.

METHODS

Mice (male 7-8 weeks old, C57BL/6J, n = 12) were divided into six groups: untreated group (control), without OTM and recovered from induced periodontitis (RP), with OTM and administered PBS or Sema3A to the gingiva after induced periodontitis (VehPO, SemaPO), with OTM and administered PBS or Sema3A to the gingiva without periodontitis induction (VehNO, SemaNO). Samples were collected on 14 days, and bone loss, histological analysis, cytokine production level, and tooth movement were assessed. Cultured human periodontal ligament (hPDL) cells were stimulated with lipopolysaccharide (LPS) and compressive force (CF), and mRNA expression levels of Sema3A and its receptors were analyzed.

RESULTS

The bone loss was significantly lower in the SemaPO group than in the VehPO group. The number of TRAP-positive cells in the SemaPO group was significantly lower than that in the VehPO group and was at the same level as that in the control group. The receptor activator of nuclear factor (NF)-kB-ligand/osteoprotegerin (RANKL/OPG) ratio and the levels of proinflammatory cytokines, including interleukin (IL)-1β, IL-6, IL-17, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, in the gingival tissues were significantly lower in the SemaPO group than in the VehPO group. Additionally, Sema3A mRNA expression in hPDL cells was significantly decreased by co-stimulation with LPS and CF compared with that in the control group. Finally, the distance moved (dist.) and the mesial tipping angle (θ) was significantly smaller in the SemaPO group than in the VehPO group and was not significantly different from that of VehNO.

CONCLUSION

Pathological alveolar bone loss exacerbated by OTM in periodontitis might be prevented by local administration of Sema3A without inhibiting OTM.

The role of Th17 cells: explanation of relationship between periodontitis and COPD?

Periodontitis and chronic obstructive pulmonary disease (COPD) are chronic inflammatory diseases with common risk factors, such as long-term smoking, age, and social deprivation. Many observational studies have shown that periodontitis and COPD are correlated. Moreover, they share a common pathophysiological process involving local accumulation of inflammatory cells and cytokines and damage of soft tissues. The T helper 17 (Th17) cells and the related cytokines, interleukin (IL)-17, IL-22, IL-1β, IL-6, IL-23, and transforming growth factor (TGF)-β, play a crucial regulatory role during the pathophysiological process. This paper reviewed the essential roles of Th17 lineage in the occurrence of periodontitis and COPD. The gaps in the study of their common pathological mechanism were also evaluated to explore future research directions. Therefore, this review can provide study direction for the association between periodontitis and COPD and new ideas for the clinical diagnosis and treatment of the two diseases.

Targeting Nrf2 with Probiotics and Postbiotics in the Treatment of Periodontitis

Periodontitis is a destructive disease of the tooth-surrounding tissues. Infection is the etiological cause of the disease, but its extent and severity depend on the immune–inflammatory response of the host. Immune cells use reactive oxygen species to suppress infections, and there is homeostasis between oxidative and antioxidant mechanisms during periodontal health. During periodontitis, however, increased oxidative stress triggers tissue damage, either directly by activating apoptosis and DNA damage or indirectly by activating proteolytic cascades. Periodontal treatment aims to maintain an infection and inflammation-free zone and, in some cases, regenerate lost tissues. Although mechanical disruption of the oral biofilm is an indispensable part of periodontal treatment, adjunctive measures, such as antibiotics or anti-inflammatory medications, are also frequently used, especially in patients with suppressed immune responses. Recent studies have shown that probiotics activate antioxidant mechanisms and can suppress extensive oxidative stress via their ability to activate nuclear factor erythroid 2-related factor 2 (Nrf2). The aim of this narrative review is to describe the essential role of Nrf2 in the maintenance of periodontal health and to propose possible mechanisms to restore the impaired Nrf2 response in periodontitis, with the aid of probiotic and postbiotics.

Interleukin-34 Permits Porphyromonas gingivalis Survival and NF-κB p65 Inhibition in Macrophages

Interleukin-34 (IL-34) is a cytokine that supports the viability and differentiation of macrophages. An important cytokine for the development of epidermal immunity, IL-34 is present and plays a role in the immunity of the oral environment. IL-34 has been linked to inflammatory periodontal diseases, which involve innate phagocytes, including macrophages. Whether IL-34 can alter the ability of macrophages to effectively interact with oral microbes is currently unclear. Using macrophages derived from human blood monocytes with either the canonical cytokine colony-stimulating factor (CSF)1 or IL-34, we compared the ability of the macrophages to phagocytose, kill, and respond through the production of cytokines to the periodontal keystone pathogen Porphyromonas gingivalis. While macrophages derived from both cytokines were able to engulf the bacterium equally, IL-34 derived macrophages were much less capable of killing internalized P. gingivalis. Of the macrophage cell surface receptors known to interact with P. gingivalis, DC-SIGN was found to have the largest variation between IL-34 and CSF1-derived macrophages. We also found that upon interaction with P. gingivalis, IL-34 derived macrophages produced significantly less of the neutrophil chemotactic factor IL-8 than macrophages derived in the presence of CSF1. Mechanistically, we identified that levels of IL-8 corresponded with P. gingivalis survival and dephosphorylation of the major transcription factor NF-κB p65. Overall, we found that macrophages differentiated in the presence of IL-34, a dominant cytokine in the oral gingiva, have a reduced ability to kill the keystone pathogen P. gingivalis and may be susceptible to specific bacteria-mediated cytokine modification. This article is protected by copyright. All rights reserved.

mTOR Signaling in the Regulation of CD4+ T Cell Subsets in Periodontal Diseases

Periodontal disease results from the inflammatory infiltration by the microbial community which is marked through tooth mobility and alveolar bone resorption. The inflammation in periodontal disease is mediated by CD4⁺ T cells through cytokine secretion and osteoclastogenetic activity. Historically, the inflammatory model in periodontal disease is described through disruption of the balance between two subsets of T helper cells which are T-helper type 1 (Th1) and T-helper type 2 (Th2). However, more and more studies have found that apart from subsets of helper T cells, regulatory T-cells and Th17 cells are also involved in the pathogenesis of periodontal diseases. Growing evidence proves that helper T cells differentiation, activation, and subset determination are under the strong impact of mTOR signaling. mTOR signaling could promote Th1 and Th17 cell differentiation and inhibit Treg commitment through different mTOR complexes, therefore we anticipate a regulation effect of mTOR signaling on periodontal diseases by regulating CD4⁺ T cell subsets. This review aims to integrate the topical researches about the role of different types of Th cells in the pathogenesis of periodontal diseases, as well as the regulation of mTOR signaling in the specification and selection of Th cell commitment.

Longitudinal follow-up study of the association between statin use and chronic periodontitis using national health screening cohort of Korean population

Since a potential link between statins and the risk of adverse chronic periodontitis (CP) has been raised, we aimed to validate the association between statin use and the incidence of CP using nationwide cohort data. This longitudinal follow-up study included 169,381 patients prescribed statins who were matched with an equal number of controls using propensity scores from the Korean National Health Insurance Service-Health Screening Cohort database (2002–2015). A Cox proportional hazard model was used to assess the occurrence of CP following statin use after adjusting for multiple covariates. The occurrence of CP was significantly higher in patients who had long-term use (1–3 years, 3–5 years, or > 5 years) than with short-term use (≤ 1 year) of statins. After adjustment, statin users exhibited an occurrence of CP 1.32-fold higher (95% confidence interval 1.30–1.33) than that of the matched nonusers (incidence: 25.0 and 22.0 per 100 person-years, respectively). Subgroup analyses supported the adverse impact of statins on CP independent of age and gender. Statin user odds ratios for developing CP were higher compared to those of nonusers. This was consistent in individuals aged > 40 years in both genders, especially with long-term use.