Mitochondrial abnormalities are involved in periodontal ligament fibroblast apoptosis induced by oxidative stress

New insights into the role of mitochondrial dynamics in oxidative stress-induced diseases

The accumulation of excess reactive oxygen species (ROS) can lead to oxidative stress (OS), which can induce gene mutations, protein denaturation, and lipid peroxidation directly or indirectly. The expression is reduced ATP level in cells, increased cytoplasmic Ca2+, inflammation, and so on. Consequently, ROS are recognized as significant risk factors for human aging and various diseases, including diabetes, cardiovascular diseases, and neurodegenerative diseases. Mitochondria are involved in the production of ROS through the respiratory chain. Abnormal mitochondrial characteristics, including mitochondrial OS, mitochondrial fission, mitochondrial fusion, and mitophagy, play an important role in various tissues. However, previous excellent reviews focused on OS-induced diseases. In this review, we focus on the latest progress of OS-induced mitochondrial dynamics, discuss OS-induced mitochondrial damage-related diseases, and summarize the OS-induced mitochondrial dynamics-related signaling pathways. Additionally, it elaborates on potential therapeutic methods aimed at preventing oxidative stress from further exacerbating mitochondrial disorders.

Mitochondrial biogenesis disorder and oxidative damage promote refractory apical periodontitis in rat and human

AIM

To elucidate whether mitochondrial biogenesis disorder and damage from oxidative stress promote refractory apical periodontitis (RAP) in rat and human.

METHODOLOGY

Twenty Enterococcus faecalis-induced RAPs were established in the maxillary first molars of male Wistar rats. Concurrently, 12 periapical lesion specimens from patients presenting with RAP were obtained by apicoectomy. Radiographic examination and histologic analysis were conducted to evaluate periapical bone tissue destruction and morphological changes. The expression of key regulators of mitochondrial biogenesis, PGC-1α and Nrf2, were detected by immunohistochemistry and double immunofluorescence staining, Western blot and real-time PCR were also assayed. Mitochondrial ROS (mtROS) was identified by MitoSOX staining. Mitochondrial function was detected by the quantification of ATP production, mitochondrial DNA (mtDNA) copy number and activities of mitochondrial respiratory chain complexes. Furthermore, mitochondrial oxidative stress was evaluated by the determination of 3-nitrotyrosine (3-NT), 4-hydroxy-2-nonenal (4-HNE) and 8-hydroxy-deoxyguanosine (8-OHdG) expression levels, as well as malondialdehyde (MDA) expression and antioxidant capacity. Student's t-test was performed to determine significance between the groups; p < .05 was considered significant.

RESULTS

In the maxilla, significantly more bone resorption, greater number of periapical apoptotic cells and Tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells were observed in the RAP group compared with the control group (p < .01). PGC-1α and Nrf2 were significantly reduced in rat and human RAP lesions compared to the control group (p < .01) at both the mRNA and protein levels. Double immunofluorescence analysis of PGC-1α or Nrf2 with TOMM20 also indicated that mitochondrial biogenesis was impaired in RAP group (p < .01). Additionally, mitochondrial dysfunction was observed in RAP group, as reflected by increased mtROS, decreased ATP production, reduced mtDNA copy number and complexes of the mitochondrial respiratory chain. Finally, the expression levels of mitochondrial oxidative stress markers, 3-NT, 4-HNE and 8-OHdG, were significantly increased in the RAP group (p < .01). Consistent with this, systemic oxidative damage was also present in the progression of RAP, including increased MDA expression and decreased antioxidant activity (p < .01).

CONCLUSIONS

Mitochondrial biogenesis disorder and damage from oxidative stress contribute to the development of RAP.

The Interplay of Mitochondrial Dysfunction in Oral Diseases: Recent Updates in Pathogenesis and Therapeutic Implications

Mitochondrial dysfunction is linked to various systemic and localized diseases, including oral diseases like periodontitis, oral cancer, and temporomandibular joint disorders. This paper explores the intricate mechanisms underlying mitochondrial dysfunction in oral pathologies, encompassing oxidative stress, inflammation, and impaired energy metabolism. Furthermore, it elucidates the bidirectional relationship between mitochondrial dysfunction and oral diseases, wherein the compromised mitochondrial function exacerbates disease progression, while oral pathologies, in turn, exacerbate mitochondrial dysfunction. Understanding these intricate interactions offers insights into novel therapeutic strategies targeting mitochondrial function for managing oral diseases. This paper pertains to the mechanisms underlying mitochondrial dysfunction, its implications in various oral pathological and inflammatory conditions, and emerging versatile treatment approaches. It reviews current therapeutic strategies to mitigate mitochondrial dysfunction, including antioxidants, mitochondrial-targeted agents, and metabolic modulators.

Mitochondrial function in oral health and disease

Monitoring mitochondrial function and mitochondrial quality control in tissues is a crucial aspect of understanding cellular health and dysfunction, which may inform about the pathogenesis of several conditions associated with aging, including chronic inflammatory conditions, neurodegenerative disorders and metabolic diseases. This process involves assessing the functionality, integrity, and abundance of mitochondria within cells. Several lines of evidence have explored techniques and methods for monitoring mitochondrial quality control in tissues. In this review, we summarize and provide our perspective considering the latest evidence in mitochondrial function and mitochondrial quality control in oral health and disease with a particular focus in periodontal inflammation. This research is significant for gaining insights into cellular health and the pathophysiology of periodontal disease, a dysbiosis-related, immune mediated and age-associated chronic condition representing a significant burden to US elderly population. Approaches for assessing mitochondrial health status reviewed here include assessing mitochondrial dynamics, mitophagy, mitochondrial biogenesis, oxidative stress, electron transport chain function and metabolomics. Such assessments help researchers comprehend the role of mitochondrial function in cellular homeostasis and its implications for oral diseases.

Regulatory role of PDK1 via integrated gene analysis of mitochondria-immune response in periodontitis

AIMS

To investigate the association between mitochondrial events and immune response in periodontitis and related regulatory genes.

MAIN METHODS

Gene expression profiles in gingival tissues were retrieved from the Gene Expression Omnibus. Mitochondria-immune response-related differentially expressed genes (MIR-DEGs) between the healthy and periodontitis samples were determined. WGCNA, GO, and KEGG were used to investigate the function and the enriched pathways of MIR-DEGs. The correlation between MIR-DEGs expression and clinical probing pocket depth was analyzed. The MIR-DEGs were further identified and verified in animal samples. A periodontitis model was established in C57BL/6 mice with silk ligation. Micro-computed tomography was used to assess alveolar bone loss. Western blot, quantitative real-time polymerase chain reaction, and immunohistochemical analyses further validated the differential expression of the MIR-DEGs.

KEY FINDINGS

A total of ten MIR-DEGs (CYP24A1, PRDX4, GLDC, PDK1, BCL2A1, CBR3, ARMCX3, BNIP3, IFI27, and UNG) were identified, the expression of which could effectively distinguish patients with periodontitis from the healthy controls. Enhanced immune response was detected in the periodontitis group with that in the healthy controls, especially in B cells. PDK1 was a critical MIR-DEG correlated with B cell immune response and clinical periodontal probing pocket depth. Both animal and clinical periodontal samples presented higher gene and protein expression of PDK1 than the control samples. Additionally, PDK1 colocalized with B cells in both animal and clinical periodontal tissues.

SIGNIFICANCE

Mitochondria participate in the regulation of the immune response in periodontitis. PDK1 may be the key mitochondria-related gene regulating B-cell immune response in periodontitis.

The role of oxidative stress biomarkers in the development of peri-implant disease: A systematic review and meta-analysis

OBJECTIVES

To analyze the role of oxidative stress (OS) biomarkers in peri‑implant diseases using a systematic review and meta-analysis approach. DATE: The review incorporated cross-sectional studies, randomized controlled trials, and case-control trials to evaluate the differences in OS biomarkers of peri‑implant disease.

SOURCES

A comprehensive literature search was conducted in electronic databases such as PubMed, Scopus, Embase, Web of Science, and CNKI, and no restrictions were applied during the search process.

STUDY SELECTION

A total of 452 studies were identified, of which 18 were eligible for inclusion. Risk of bias and sensitivity analysis were assessed using Egger's test and funnel plots.

RESULTS

We found that the levels of glutathione peroxidase (GSH-Px) in the peri‑implant sulcus fluid (PISF) of patients with peri‑implant diseases were significantly reduced (SMD = -1.40; 95 % CI = 1.70, -1.11; p < 0.001), while the levels of total myeloperoxidase (MPO) and malondialdehyde (MDA) were significantly increased (SMD = 0.46; 95 % CI = 0.12, 0.80; p = 0.008; SMD = 0.28; 95 % CI = 0.01, 0.56; p = 0.043). However, there were no significant differences of MPO concentration (SMD = 0.38; 95 % CI = -0.39, 1.15; p = 0.331) and superoxide dismutase (SOD)(SMD = -0.43; 95 % CI = -1.94, 1.07; p = 0.572) in PISF between peri‑implant disease group and control group. Similarly, salivary MPO did not show significant differences (SMD = 1.62; 95 % CI = -1.01, 4.24; p = 0.227).

CONCLUSIONS

Our results supported that the level of local OS biomarkers was closely related to peri‑implant diseases. GSH-Px, total MPO and MDA may be PISF biomarkers with good capability to monitor the development of peri‑implant disease.

CLINICAL SIGNIFICANCE

This study found significant differences in the levels of local OS biomarkers (GSH-Px, total MPO, and MDA) between patients with peri‑implant diseases and healthy subjects, which may be ideal candidate biomarkers for predicting and diagnosing peri‑implant diseases.

Exploring the potential link between MitoEVs and the immune microenvironment of periodontitis based on machine learning and bioinformatics methods

BACKGROUND

Periodontitis is a chronic inflammatory condition triggered by immune system malfunction. Mitochondrial extracellular vesicles (MitoEVs) are a group of highly heterogeneous extracellular vesicles (EVs) enriched in mitochondrial fractions. The objective of this research was to examine the correlation between MitoEVs and the immune microenvironment of periodontitis.

METHODS

Data from MitoCarta 3.0, GeneCards, and GEO databases were utilized to identify differentially expressed MitoEV-related genes (MERGs) and conduct functional enrichment and pathway analyses. The random forest and LASSO algorithms were employed to identify hub MERGs. Infiltration levels of immune cells in periodontitis and healthy groups were estimated using the CIBERSORT algorithm, and phenotypic subgroups of periodontitis based on hub MERG expression levels were explored using a consensus clustering method.

RESULTS

A total of 44 differentially expressed MERGs were identified. The random forest and LASSO algorithms identified 9 hub MERGs (BCL2L11, GLDC, CYP24A1, COQ2, MTPAP, NIPSNAP3A, FAM162A, MYO19, and NDUFS1). ROC curve analysis showed that the hub gene and logistic regression model presented excellent diagnostic and discriminating abilities. Immune infiltration and consensus clustering analysis indicated that hub MERGs were highly correlated with various types of immune cells, and there were significant differences in immune cells and hub MERGs among different periodontitis subtypes.

CONCLUSION

The periodontitis classification model based on MERGs shows excellent performance and can offer novel perspectives into the pathogenesis of periodontitis. The high correlation between MERGs and various immune cells and the significant differences between immune cells and MERGs in different periodontitis subtypes can clarify the regulatory roles of MitoEVs in the immune microenvironment of periodontitis. Future research should focus on elucidating the functional mechanisms of hub MERGs and exploring potential therapeutic interventions based on these findings.

Mitochondrial Dysfunction in Periodontitis and Associated Systemic Diseases: Implications for Pathomechanisms and Therapeutic Strategies

Periodontitis is a chronic infectious disorder damaging periodontal tissues, including the gingiva, periodontal ligament, cementum, and alveolar bone. It arises from the complex interplay between pathogenic oral bacteria and host immune response. Contrary to the previous view of "energy factories", mitochondria have recently been recognized as semi-autonomous organelles that fine-tune cell survival, death, metabolism, and other functions. Under physiological conditions, periodontal tissue cells participate in dynamic processes, including differentiation, mineralization, and regeneration. These fundamental activities depend on properly functioning mitochondria, which play a crucial role through bioenergetics, dynamics, mitophagy, and quality control. However, during the initiation and progression of periodontitis, mitochondrial quality control is compromised due to a range of challenges, such as bacterial-host interactions, inflammation, and oxidative stress. Currently, mounting evidence suggests that mitochondria dysfunction serves as a common pathological mechanism linking periodontitis with systemic conditions like type II diabetes, obesity, and cardiovascular diseases. Therefore, targeting mitochondria to intervene in periodontitis and multiple associated systemic diseases holds great therapeutic potential. This review provides advanced insights into the interplay between mitochondria, periodontitis, and associated systemic diseases. Moreover, we emphasize the significance of diverse therapeutic modulators and signaling pathways that regulate mitochondrial function in periodontal and systemic cells.

Mitochondrial Dysfunction in the Pathogenesis and Treatment of Oral Inflammatory Diseases

Oral inflammatory diseases (OIDs) include many common diseases such as periodontitis and pulpitis. The causes of OIDs consist microorganism, trauma, occlusal factors, autoimmune dis-eases and radiation therapy. When treated unproperly, such diseases not only affect oral health but also pose threat to people's overall health condition. Therefore, identifying OIDs at an early stage and exploring new therapeutic strategies are important tasks for oral-related research. Mitochondria are crucial organelles for many cellular activities and disruptions of mitochondrial function not only affect cellular metabolism but also indirectly influence people's health and life span. Mitochondrial dysfunction has been implicated in many common polygenic diseases, including cardiovascular and neurodegenerative diseases. Recently, increasing evidence suggests that mitochondrial dysfunction plays a critical role in the development and progression of OIDs and its associated systemic diseases. In this review, we elucidated the critical insights into mitochondrial dysfunction and its involvement in the inflammatory responses in OIDs. We also summarized recent research progresses on the treatment of OIDs targeting mitochondrial dysfunction and discussed the underlying mechanisms.

The role of mitochondrial dysfunction in periodontitis: From mechanisms to therapeutic strategy

Periodontitis is an inflammatory and destructive disease of tooth-supporting tissue and has become the leading cause of adult tooth loss. The most central pathological features of periodontitis are tissue damage and inflammatory reaction. As the energy metabolism center of eukaryotic cells, mitochondrion plays a notable role in various processes, such as cell function and inflammatory response. When the intracellular homeostasis of mitochondrion is disrupted, it can lead to mitochondrial dysfunction and inability to generate adequate energy to maintain basic cellular biochemical reactions. Recent studies have revealed that mitochondrial dysfunction is closely related to the initiation and development of periodontitis. The excessive production of mitochondrial reactive oxygen species, imbalance of mitochondrial biogenesis and dynamics, mitophagy and mitochondrial DNA damage can all affect the development and progression of periodontitis. Thus, targeted mitochondrial therapy is potentially promising in periodontitis treatment. In this review, we summarize the above mitochondrial mechanism in the pathogenesis of periodontitis and discuss some potential approaches that can exert therapeutic effects on periodontitis by modulating mitochondrial activity. The understanding and summary of mitochondrial dysfunction in periodontitis might provide new research directions for pathological intervention or treatment of periodontitis.

Perturbation of mitochondrial dynamics links to the aggravation of periodontitis by diabetes

Diabetes and periodontitis are prevalent diseases that considerably impact global economy and diabetes is a major risk factor of periodontitis. Mitochondrial dynamic alterations are involved in many diseases including diabetes and this study aims to evaluate their relevance with diabetes aggravated periodontitis. Sixty mice are randomly divided into 4 groups: control, periodontitis, diabetes and diabetic periodontitis. Periodontitis severity is evaluated by alveolar bone loss, inflammation and oxidative stress status. Mitochondrial structural and functional defects are evaluated by the mitochondrial fission/fusion events, mitochondrial reactive oxygen species (ROS) accumulation, complex activities and adenosine triphosphate (ATP) production. Advanced glycation end product (AGE) and Porphyromonas gingivalis are closely related to periodontitis occurrence and development. Human gingival fibroblast cells (HGF-1) are used to investigate the AGE role and lipopolysaccharide (LPS) from Porphyromonas gingivalis (P-LPS) in aggravating diabetic periodontitis by mitochondrial dynamic and function alterations. In vivo, diabetic mice with periodontitis show severe bone loss, increased inflammation and oxidative stress accumulation. Among mice with periodontitis, diabetic mice show worse mitochondrial dynamic perturbations than lean mice, along with fusion protein levels inducing more mitochondrial fission in gingival tissue. In vitro, AGEs and P-LPS co-treatment causes severe.

Antioxidant, anti-inflammatory and antimicrobial activity of natural products in periodontal disease: a comprehensive review

Periodontal diseases (PD) are common chronic inflammatory oral pathologies that are strongly linked to others not found in the mouth cavity. The immune system mediates the host response, which includes the upregulation of proinflammatory cytokines, metalloproteinases, and reactive oxygen species (ROS); the latter may play an important role in the establishment and progression of inflammatory diseases, particularly periodontal disease, via the development of oxidative stress (OS). Natural antioxidants have powerful anti-inflammatory properties, and some can reduce serum levels of key PD indicators such tumor necrosis factor (TNF) and interleukin IL-1. This review compiles, through a thorough literature analysis, the antioxidant, anti-inflammatory, and antibacterial effects of a variety of natural products, as well as their therapeutic potential in the treatment of PD.

Activation of PGC-1α-dependent mitochondrial biogenesis supports therapeutic effects of silibinin against type I diabetic periodontitis

AIM

To investigate whether silibinin impacts diabetic periodontitis (DP) via mitochondrial regulation.

MATERIALS AND METHODS

In vivo, rats were divided into control, diabetes, DP and DP combined with silibinin groups. Diabetes and periodontitis were induced by streptozocin and silk ligation, respectively. Bone turnover was evaluated by microcomputed tomography, histology and immunohistochemistry. In vitro, human periodontal ligament cells (hPDLCs) were exposed to hydrogen peroxide (H2 O2 ) with or without silibinin. Osteogenic function was analysed by Alizarin Red and alkaline phosphatase staining. Mitochondrial function and biogenesis were investigated by mitochondrial imaging assays and quantitative polymerase chain reaction. Activator and lentivirus-mediated knockdown of peroxisome proliferator-activated receptor gamma-coactivator 1-alpha (PGC-1α), a critical regulator of mitochondria biogenesis, was used to explore the mitochondrial mechanisms.

RESULTS

Silibinin attenuated periodontal destruction and mitochondrial dysfunction and enhanced mitochondrial biogenesis and PGC-1α expression in rats with DP. Meanwhile, silibinin promoted cell proliferation, osteogenesis and mitochondrial biogenesis and increased the PGC-1α level in hPDLCs exposed to H2 O2 . Silibinin also protected PGC-1α from proteolysis in hPDLCs. Furthermore, both silibinin and activator of PGC-1α ameliorated cellular injury and mitochondrial abnormalities in hPDLCs, while knockdown of PGC-1α abolished the beneficial effect of silibinin.

CONCLUSIONS

Silibinin attenuated DP through the promotion of PGC-1α-dependent mitochondrial biogenesis.

Assessment of Oxidative Stress by the Estimation of Lipid Peroxidation Marker Malondialdehyde (MDA) in Patients with Chronic Periodontitis: A Systematic Review and Meta-Analysis

Objective

The present systematic review and meta-analysis aimed to assess the oxidative stress-mediated lipid peroxidation end product malondialdehyde (MDA) in periodontitis using the available literature.

Materials and Methods

An electronic literature search was performed for the published articles from 2000 to 2022 in PubMed (MeSH), Science Direct, Wiley Online library, and cross-reference using specific keywords.

Results

The literature search identified 1,166 articles. After analyzing the abstracts of the obtained articles, the articles were excluded for the following reasons: duplicate studies (n = 395) and not relevant to the research question (n = 726). The remaining 45 articles were chosen for full-text evaluation. Finally, the present qualitative synthesis selected 34 articles that met the inclusion criteria for evaluation and removed the articles which did not meet the required criteria (n = 11). Out of these, 16 articles had coherent data for quantitative synthesis. The meta-analysis used the standardized mean differences method at a 95% confidence interval by random-effects model. The periodontitis group displayed significantly higher MDA levels (P < 0.001) in gingival crevicular fluid, saliva, and serum samples of the studies analyzed than the healthy control.

Conclusion

The analyzed studies showed significantly higher MDA levels in various biological samples of patients with periodontitis, supporting the role of elevated oxidative stress and consequent lipid peroxidation in periodontitis.

Ginsenoside Rg1 alleviates lipopolysaccharide-induced pyroptosis in human periodontal ligament cells via inhibiting Drp1-mediated mitochondrial fission

OBJECTIVE

The present study aimed to investigate whether Ginsenoside Rg1 alleviated lipopolysaccharide (LPS) - induced pyroptosis of human periodontal ligament cells (HPDLCs) and further explore the underlying mechanism.

DESIGN

Cell viability was detected using the CCK-8 assay. Proinflammatory cytokine secretion and lactate dehydrogenase release were examined by ELISA. Flow cytometry analysis was conducted to determine the pyroptosis ratio, and ATP production was estimated using the ATP assay kit. Fluorescence staining was utilized to visualize mitochondrial morphology and analyze mitochondrial reactive oxygen species (mtROS), and the mitochondrial membrane potential level. Western blot and qRT-PCR were used to determine the expression of signaling pathway-related proteins and mRNA, respectively.

RESULTS

The results discovered that Ginsenoside Rg1 treatment enhanced cell viability in comparison to LPS stimulation, attenuated pyroptosis in HPDLCs, and reduced the release of lactate dehydrogenase, IL-1β, and IL-18 significantly. Additionally, we found that Ginsenoside Rg1 upregulated ATP content and mitochondrial membrane potential level while reducing aberrant mitochondrial fission and mtROS production. Mechanistically, we found that Ginsenoside Rg1 upregulated dynamin-related protein 1 (Drp1) phosphorylation at Ser 637 in an AMP-activated protein kinase (AMPK)-dependent manner, and reduced pyroptosis-related proteins expression, including NLRP3, ASC, Caspase-1, and GSDMD-NT.

CONCLUSIONS

These findings demonstrate that Ginsenoside Rg1 treatment attenuates LPS-induced pyroptosis and inflammation damage in HPDLCs, which may connect to the activation of the AMPK/Drp1/NLRP3 signaling pathway. Moreover, the results offer a potential theoretical foundation for applying Ginsenoside Rg1 in inflammatory diseases such as periodontitis.

Silibinin Attenuates Experimental Periodontitis by Downregulation of Inflammation and Oxidative Stress

Periodontitis is an oral microbiota-induced inflammatory disease, in which inflammation and oxidative stress play a critical role. Silibinin (SB), a Silybum marianum-derived compound, exhibits strong anti-inflammatory and antioxidative properties. We adopted a rat ligature-induced periodontitis model and a lipopolysaccharide- (LPS-) stimulated human periodontal ligament cells (hPDLCs) model to evaluate the protective effects of SB. In the in vivo model, SB reduced alveolar bone loss and apoptosis of PDLCs in the periodontal tissue. SB also maintained the expression of nuclear factor-E2-related factor 2 (Nrf2), a key regulator of cellular resistance to oxidative stress, and attenuated lipid, protein, and DNA oxidative damages in the periodontal lesion area. Meanwhile, in the in vitro model, SB administration reduced the production of intracellular reactive oxidative species (ROS). Furthermore, SB exerted a strong anti-inflammatory property in both in vivo and in vitro models by inhibiting the expression of inflammatory mediators including nuclear factor-κB (NF-κB) as well as nucleotide binding oligomerization domain- (NOD-) like receptor family pyrin domain-containing 3 (NLRP3) and downregulating the levels of proinflammatory cytokines. This study, for the first time, demonstrates that SB exhibits the anti-inflammatory and antioxidative properties against periodontitis by downregulating the expression of NF-κB and NLRP3 and upregulating Nrf2 expression, suggesting a promising potential clinical application of SB in periodontitis.

The Emerging Role of Salivary Oxidative Stress Biomarkers as Prognostic Markers of Periodontitis: New Insights for a Personalized Approach in Dentistry

Periodontitis is a multifactorial and infective oral disease that leads to the destruction of periodontal tissues and tooth loss. Although the treatment of periodontitis has improved recently, the effective treatment of periodontitis and the periodontitis-affected periodontal tissues is still a challenge. Therefore, exploring new therapeutic strategies for a personalized approach is urgent. For this reason, the aim of this study is to summarize recent advances and the potential of oxidative stress biomarkers in the early diagnosis and personalized therapeutic approaches in periodontitis. Recently, ROS metabolisms (ROMs) have been studied in the physiopathology of periodontitis. Different studies show that ROS plays a crucial role in periodontitis. In this regard, the reactive oxygen metabolites (ROMs) started to be searched for the measures of the oxidizing capacity of the plasma understood as the total content of oxygen free radicals (ROS). The oxidizing capacity of plasma is a significant indicator of the body's oxidant state as well as homocysteine (Hcy), sulfur amino acid, which has pro-oxidant effects as it favors the production of superoxide anion. More specifically, the thioredoxin (TRX) and peroxiredoxin (PRX) systems control reactive oxygen species (ROS), such as superoxide and hydroxyl species, to transduce redox signals and change the activities of antioxidant enzymes to remove free radicals. Superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx), among other antioxidant enzymes, change their activity when ROS are produced in order to neutralize free radicals. The TRX system is triggered and transduces redox signals to do this.

Crosstalk between reactive oxygen species and Dynamin-related protein 1 in periodontitis

Excessive generation of reactive oxygen species (ROS) have great impacts on the development of periodontitis. Dynamin-related protein 1 (Drp1) mediated mitochondrial fission is the main reason and the result of excessive ROS generation. However, whether Drp1 and crosstalk between ROS and Drp1 contribute to the process of periodontitis remains elusive. We herein investigated the role and functional significance of crosstalk between ROS and Drp1 in periodontitis. Firstly, human periodontal ligament cells (hPDLCs) were treated with hydrogen peroxide (H₂O₂) and ROS inhibitor N-acetyl-cysteine (NAC) or Drp1 inhibitor mitochondrial division inhibitor 1 (Mdivi-1). Cell viability, apoptosis, osteogenic differentiation, expression of Drp1, and mitochondrial function were investigated. Secondly, mice with periodontitis were treated with NAC or Mdivi-1. Finally, gingival tissues were collected from periodontitis patients and healthy individuals to evaluate ROS and Drp1 levels. H₂O₂ induced cellular injury and inflammation, excessive ROS production, mitochondrial abnormalities, and increased expression of p-Drp1 and Drp1 in hPDLCs, which could be reversed by NAC and Mdivi-1. Moreover, both NAC and Mdivi-1 ameliorated tissue damage and inflammation, and decreased expression of p-Drp1 and Drp1 in mice with periodontitis. More importantly, patients with periodontitis presented significantly higher levels of ROS-induced oxidative damage and p-Drp1 than that in healthy individuals and correlated with clinical parameters. In summary, ROS-Drp1 crosstalk greatly promotes the development of periodontitis. Pharmacological blockade of this crosstalk might be a novel therapeutic strategy for periodontitis.

Quercetin Prevents Oxidative Stress-Induced Injury of Periodontal Ligament Cells and Alveolar Bone Loss in Periodontitis

Purpose

Emerging evidence has indicated that oxidative stress (OS) contributes to periodontitis. Periodontal ligament cells (PDLCs) are important for the regeneration of periodontal tissue. Quercetin, which is extracted from fruits and vegetables, has strong antioxidant capabilities. However, whether and how quercetin affects oxidative damage in PDLCs during periodontitis remains unknown. The aim of this study was to assess the effects of quercetin on oxidative damage in PDLCs and alveolar bone loss in periodontitis and underlying mechanisms.

Materials and Methods

The tissue block culture method was used to extract human PDLCs (hPDLCs). First, a cell counting kit 8 (CCK-8) assay was used to identify the optimal concentrations of hydrogen peroxide (H₂O₂) and quercetin. Subsequently, a 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) probe, RT-qPCR, Western blotting and other methods were used to explore the effects of quercetin on OS in hPDLCs and the underlying mechanism. Finally, quercetin was administered to mice with periodontitis through gavage, and the effect of quercetin on the level of OS and alveolar bone resorption in these mice was observed by immunofluorescence, microcomputed tomography (micro-CT), hematoxylin and eosin staining (H&E) staining and so on.

Results

Quercetin at 5 μM strongly activated NF-E2-related factor 2 (NRF2) signaling, alleviated oxidative damage and enhanced the antioxidant capacity of hPDLCs. In addition, quercetin reduced cellular senescence and protected the osteogenic ability of hPDLCs. Finally, quercetin activated NRF2 signaling in the periodontal ligaments, reduced the OS level of mice with periodontitis, and slowed the absorption of alveolar bone in vivo.

Conclusion

Quercetin can increase the antioxidant capacity of PDLCs and reduce OS damage by activating the NRF2 signaling pathway, which alleviates alveolar bone loss in periodontitis.

Leptin attenuates hypoxia-induced apoptosis in human periodontal ligament cells via the reactive oxygen species-hypoxia-inducible factor-1α pathway

NEW FINDINGS

What is the central question of this study? Does leptin have an effect on hypoxia-induced apoptosis in human periodontal ligament cells (hPDLCs), and what is the potential underlying mechanism? What is the main finding and its importance? Hypoxia induces cell apoptosis and leptin expression in hPDLCs through the induction of hypoxia-inducible factor-1α and accumulation of reactive oxygen species (ROS). Leptin shows feedback inhibition on hypoxia-induced ROS-mediated apoptosis in hPDLCs, suggesting a new application of leptin for hypoxic damage in periodontal diseases.

ABSTRACT

Hypoxia-induced apoptosis of human periodontal ligament cells (hPDLCs) is an important contributor to the progression of various periodontal diseases. Although leptin has been shown to protect connective tissue cells against hypoxia-induced injury, whether it might do so by attenuating hypoxia-induced apoptosis in hPDLCs remains unclear. Here, using CoCl₂ treatment, we simulated hypoxic conditions in hPDLCs and explored whether apoptosis and reactive oxygen species (ROS) levels were related to hypoxia. After small interfering RNA (siRNA) inhibition of leptin and hypoxia-inducible factor-1α (HIF-1α), the levels of apoptosis, ROS and leptin expression were measured. We showed that in CoCl₂ -treated hPDLCs, significantly higher cell apoptosis rates and ROS accumulation were observed. Cobalt chloride also increased leptin and HIF-1α expression in hPDLCs. Further investigation of the pathway demonstrated that inhibition of ROS attenuated hypoxia-induced cell apoptosis and leptin expression, whereas siRNA inhibition of leptin aggravated hypoxia-induced cell apoptosis and ROS accumulation. Hypoxia induces cell apoptosis and leptin expression in hPDLCs through the induction of ROS and HIF-1α pathways, and leptin shows feedback inhibition on ROS-mediated apoptosis in hPDLCs. These findings suggest a new application of leptin for hypoxic damage in periodontal diseases.

Effect of periodontitis on oxidative stress parameters in patients with rheumatic heart valve disease

OBJECTIVE

The aim of this study was to evaluate the effects of periodontitis on oxidative stress parameters by investigating serum and gingival crevicular fluid (GCF) total antioxidant capacity (TAOC), total oxidant status (TOS), and oxidative stress index (OSI) values in patients with rheumatic heart valve disease (RHVD).

MATERIALS AND METHODS

The study population comprised 76 patients, who were divided into four groups: chronic periodontitis with RVHD (RV-CP), periodontally healthy with RVHD (RV-C), systemically healthy with chronic periodontitis (CP), and systemically and periodontally healthy (C). Demographic, periodontal, and echocardiographic parameters were measured. Serum and GCF oxidative stress parameters were evaluated based on the OSI.

RESULTS

Similar serum oxidative stress parameters were found in all study groups (P ≥ 0.05). The GCF TAOC values of the C group were significantly higher than those of the other groups (P = 0.001). The GCF OSI values of the C group were significantly lower than those of the other groups (P = 0.001). The GCF TOS and OSI values of the RV-CP group were significantly higher than those of the CP and C groups (P = 0.001). The GCF TOS value of the RV-C group was significantly higher than those of the CP and C groups (P = 0.001).

CONCLUSIONS

Altered local oxidative stress profile was associated with the presence of periodontitis. Rheumatic heart valve disease may increase oxidative stress in individuals with chronic periodontitis.

Oxidative stress-related biomarkers in saliva and gingival crevicular fluid associated with chronic periodontitis: A systematic review and meta-analysis

AIM

Oxidative stress (OS) biomarkers have been detected in saliva and gingival crevicular fluid (GCF) during chronic periodontitis (CP) progression; however, the relationship between OS biomarkers and CP progression remains elusive. The purpose of this meta-analysis is to investigate the relationship between local OS biomarkers and CP.

METHODS

This review was conducted through a systematic search from three databases. Studies on CP participants were included as an experimental group, and studies on periodontally healthy (PH) participants were included as a control. Mean effects were expressed as standardized mean difference with their associated 95% confidence intervals.

RESULTS

From a total of 2,972 articles, 32 articles fulfilled the inclusion criteria. We found a significant decrease of total antioxidant capacity and a significant increase of malondialdehyde (MDA), nitric oxide, total oxidant status (TOS), and 8-hydroxy-deoxyguanosine levels in the saliva of CP patients. Moreover, we also found an elevation of MDA level in GCF of CP group when compared with the PH group. There were no significant differences of salivary and GCF superoxide dismutase levels, salivary glutathione peroxidase level, and GCF TOS level between two groups. However, a high heterogeneity was observed among evaluated studies.

CONCLUSIONS

Despite the limitations of this study, the result of our meta-analysis supported the rationale that there was a direct link between CP and OS-related biomarkers' levels in the local site, indicating the important role of OS in the onset and development of CP.

Hydrogen sulfide-induced oxidative stress leads to excessive mitochondrial fission to activate apoptosis in broiler myocardia

Hydrogen sulfide (H₂S), as an environmental gas pollutant, has harmful effects on many tissues and organs, including myocardium. However, the underlying mechanisms of H2S-induced myocardia toxicity remain poorly understood. The present study was designed to investigate the effect of H₂S on myocardia injury in broilers from the perspective of apoptosis. 30 ppm H2S was administered in the broiler chamber for 2, 4 and 6 week, respectively, and the myocardial samples in control groups and H2S groups were collected immediately after euthanized broilers. Transmission electron microscope, test kits, qRT-PCR and western blot were performed. Results showed that H₂S exposure decreased the activities of catalase (CAT) and total antioxidant capability (T-AOC), whereas the content of hydrogen peroxide (H₂O₂) and the activity of inducible nitric oxide synthase (iNOS) enhanced. Besides, we found the excessive expression of mitochondrial fission genes (Drp1 and Mff) by H₂S, the dynamic balance of mitochondrial fission and fusion is destroyed. Furthermore, the levels of pro-apoptotic gene (including CytC, Cas3, Cas8, Cas9, TNF-α and Bax) increased after H₂S exposure, as well as the expression level of anti-apoptotic gene bcl-2 decreased. At the same time, the activities of ATPase (including Na⁺-K⁺-ATPase, Ca²⁺-ATPase, Mg²⁺-ATPase and Ca²⁺-Mg²⁺-ATPase) weakened under H₂S exposure. Therefore, we conclude that H₂S induced oxidative stress and then leaded to excessive mitochondrial fission, which involved in apoptosis and damage broiler myocardia.

DNA Laddering to Evaluate Cytogenetic Damage in Patients with Periodontitis

Background:

Inflammatory conditions show cytogenetic damage in peripheral blood leukocytes and this can be assessed using various tests. Cytogenetic damage as observed in the peripheral blood cells, is a marker of periodontal disease. DNA laddering is a sensitive assay which evaluates the cytogenetic damage. DNA laddering is a feature that can be observed when DNA fragments, resulting from apoptotic DNA fragmentation, are visualised after separation by gel electrophoresis which results in a characteristic “ladder” pattern.

Aim:

The aim of the present study is to investigate the cytogenetic damage in different forms of periodontitis in comparison with healthy controls.

Materials and Methods:

In this cross-sectional study, 15 systemically healthy subjects with moderate to severe chronic periodontitis (CGP), 15 systemically healthy subjects with generalised aggressive periodontitis(GAP) and 15 systemically healthy control subjects were recruited. Blood samples of the patients were drawn and evaluated for the cytogenetic damage by DNA laddering.

Results:

Apoptotic DNA fragmentation was observed as a “ladder” pattern at 180-200 BP intervals in both CGP and GAP groups indicating the DNA damage, in contrast with the healthy group where the ladder pattern was not observed suggesting of the healthy DNA.

Conclusion:

The results indicated that there are cytogenetic damages in both the chronic and aggressive periodontitis groups incontrast to the healthy controls.