Pathways that Regulate ROS Scavenging Enzymes, and Their Role in Defense Against Tissue Destruction in Periodontitis

Hydroxytyrosol prevents periodontitis-induced bone loss by regulating mitochondrial function and mitogen-activated protein kinase signaling of bone cells

Reactive oxygen species (ROS) overproduction promotes the alveolar bone loss during the development of periodontitis. Mitochondria are the principal source of ROS. Hydroxytyrosol (HT), a natural phenolic compound present in olive oil, is well known for its antioxidant and mitochondrial-protective prosperities. Nonetheless, the impact of HT on periodontitis and its related mechanisms underlying bone cell behavior remains unknown. Osteoclasts differentiated from RAW264.7 model and oxidative stress (OS) induced pre-osteoblast MC3T3-E1 cell injury model were treated with and without HT. Cell viability, apoptosis, differentiation, mitochondrial function along with mitogen-activated protein kinase (MAPK) signaling pathway were investigated. Meanwhile, the effect and related mechanisms of HT on bone loss in mice with periodontitis were also detected. HT inhibited osteoclast differentiation and prevented OS induced pre-osteoblast cells injury via regulating mitochondrial function as well as ERK and JNK signaling pathways. Moreover, HT attenuated the alveolar bone loss, increased bone forming activity, inhibited the osteoclasts differentiation and decreased the level of OS in mice with periodontitis. Our findings, for the first time, revealed a novel function of HT in bone remodeling of periodontitis, and highlighted its therapeutical potential for the prevention/treatment of periodontitis.

Remodeling the periodontitis microenvironment for osteogenesis by using a reactive oxygen species-cleavable nanoplatform

Modestly removing the excessive reactive oxygen species (ROS) plays a crucial role in regulating the microenvironment of periodontitis and provides favorable conditions for osteogenesis. However, the current strategy for scavenging ROS is not controllable, substantially limiting the outcomes in periodontitis. Herein, we introduced a controllable ROS-scavenging nanoplatform by encasing N-acetylcysteine (NAC, (a well-known ROS scavenger) into tailor-made ROS-cleavable amphiphilic polymer nanoparticles (PEG-ss-PCL NPs) as an intracellular delivery carrier. The existing ROS in the inflammatory microenvironment facilitated polymer degradation via breakage of thioketal bonds, and then led to encapsulated NAC release. NAC eliminated all ROS induced by lipopolysaccharide (LPS), while PssL-NAC adjusted the ROS level slightly higher than that of the control group. The percentage of apoptotic cells cultured with NAC and PssL-NAC decreased observably compared with that of cells cultured with 10 µg/ml LPS. The microenvironment regulated by PssL-NAC was highly suitable for osteogenic differentiation based on PCR and Western blot results, which showed higher expression levels of BMP2, Runx2, and PKA. Analysis of ALP activity and Alizarin red S staining showed consistent results. Additionally, the injection of PssL-NAC into the periodontitis area could alleviate the tissue destruction induced by ligation of the maxillary second molar. PssL-NAC showed a better ability to decrease osteoclast activity and inflammation, consequently improving the restoration of destroyed tissue. Our study suggests that ROS-responsive polymer nanoparticles loaded with NAC (PssL-NAC) can be new promising materials for the treatment of periodontitis. STATEMENT OF SIGNIFICANCE: More and more studies indicate that periodontal tissue damage is closely related to the high reactive oxygen species (ROS) environment. Excessive ROS will aggravate periodontal tissue damage and is not conducive to tissue repair. However, as an essential signal molecule in human physiological activities, ROS absence is also useless for tissue repair. In this study, we proposed to improve ROS imbalance in the environment of periodontitis as a strategy to promote periodontal regeneration and successfully synthesized a smart drug-releasing nanoplatform that can respond to ROS. Besides, we validated its ability to regulate the ROS environment and promote osteogenesis through experimental data in vivo and in vitro.

Histopathological and immunohistochemical study of periodontal changes in chronic smokers

Periodontal disease is a chronic inflammatory, multifactorial condition, that, in the absence of an early and adequate treatment, may lead to a progressive damaging of the alveolar tissues that support the teeth (periodontal ligament, cement and alveolar bone) followed by teeth mobility and, subsequently, their loss. Periodontal disease is one of the most common inflammatory disease affecting adult individuals all over the world, being considered a real worldwide pandemic. This disease may influence the progression of certain systemic diseases: diabetes mellitus, cardiovascular diseases, ischemic cardiomyopathy, myocardial infarction, stroke, neurodegenerative diseases, chronic kidney diseases, cancer, etc. The association between smoking and periodontal disease was described in numerous clinical and epidemiological studies, suggesting that products derived from tobacco burning may change the clinical aspects and the disease progression. The present study analyzed microscopically and immunohistochemically 58 periodontal fragments, from 50 patients, chronic smokers, clinically diagnosed with severe periodontitis. There were highlighted major changes in the gingival epithelium (epithelium thickening, acanthosis, intraepithelial edema, infiltrates of neutrophils or lymphocytes, epithelial necrosis), in the periodontal conjunctive tissue (more or less intense inflammatory infiltrates, microhemorrhages, vascular congestion, intense immunohistochemical expression for some matrix metalloproteinases). The periodontal changes may be the expression of both toxic factors present in tobacco smoke and due to the changes caused by tobacco in the microbial flora of the oral cavity.

The effect of ellagic acid on the repair process of periodontal defects related to experimental periodontitis in rats

Objective

This study aims to evaluate the effect of ellagic acid (EA) by measuring the levels of alveolar bone resorption and inflammatory and oxidative stress markers in the periodontal tissues and serum on the periodontal repair process related to experimental periodontitis in rats.

Methodology

Forty Wistar rats were divided into four study groups as follows: Group 1=healthy control (n=10); Group 2=EA control (15 mg/kg)(n=10); Group 3=periodontitis (n=10); Group 4=periodontitis+EA (15 mg/kg) (n=10). The periodontitis model was established by ligating bilateral mandibular first molars for 14 days. Then, rats were given normal saline or EA for another 14 days by gavage administration. Serum and gingiva myeloperoxidase (MPO) activity, 8-hydroxydeoxyguanosine(8-OHdG), and glutathione (GSH) levels were analyzed by ELISA. İmmunohistochemical analysis was used to detect Interleukin (IL)-6, IL-10, and tumor necrosis factor-alpha (TNF-α) immunoreactivities in the periodontal tissues. Alveolar bone loss (ABL) and attachment loss (AL) was evaluated by histomorphometry analysis.

Results

ABL and AL were statistically higher in group 3 than in groups 1, 2 and 4 and in group 4 than in groups 1 and 2 (p<0.05). MPO activities in gingival tissue and serum were significantly increased in group 3 compared to groups 1 and 2 (p<0.05). Significantly higher serum GSH levels, lower gingiva, and serum 8-OHdG levels, and MPO activity were observed in group 4 compared to group 3 (p<0.05). Rats with periodontitis (group 3) expressed significantly higher immunoreactivities of IL-6 and TNF-α and lower IL-10 immunoreactivity compared to those other groups (p<0.05). IL-6 and TNF-α immunoreactivities significantly decreased and IL-10 immunoreactivity increased in group 4 after the use of EA compared to group 3 (p<0.001).

Conclusions

Our findings showed that EA provides significant improvements on gingival oxidative stress and inflammatory markers and alveolar bone resorption in the repair process associated with experimental periodontitis. Therefore, EA may have a therapeutic potential on periodontitis.

Effects of taxifolin on bone formation and apoptosis in experimental periodontitis in diabetic rats

We investigated the therapeutic potential of taxifolin for treatment of alveolar bone loss (ABL) in experimental periodontitis in diabetic rats. Diabetes mellitus (DM) was induced by streptozotocin. Rats were divided into six groups: untreated control; DM only (D) group; ligature only (P) group; DM + ligature (DP) group; DM + ligature + 5 mg/kg/day taxifolin (Taxi-5) group; DM + ligature + 10 mg/kg/day taxifolin (Taxi-10) group. Experimental periodontitis was induced by ligation of the first molar and allowed to progress for 30 days before performing cone-beam computed tomographic (CBCT), histomorphometric and immunohistochemical analyses of periodontal tissue destruction. ABL was assessed using CBCT. ABL was greatest in the P and DP groups. Decreased ABL was observed in the Taxi-5 and Taxi-10 groups. Bone morphogenic protein (BMP-2), osteocalcin (OCN), receptor activator of nuclear factor kappa-Β ligand (RANKL), alkaline phosphatase (ALP), type I collagen, B cell lymphoma-associated X (Bax), and B-cell lymphoma 2 (Bcl-2) levels were investigated using immunohistochemistry. The Taxi-5 and Taxi-10 groups exhibited decreased RANKL expression, but increased BMP-2, ALP, type I collagen and OCN levels compared to the P and DP groups. Bax activity was increased in the D, P and DP groups. Taxi-5 and Taxi-10 groups exhibited increased Bcl-2 activity. Our findings suggest that taxifolin can reduce apoptosis and improve alveolar bone formation in diabetic rats with periodontitis.

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.

Serum Inflammatory and Prooxidant Marker Levels in Different Periodontal Disease Stages

BACKGROUND

Periodontitis has been associated to systemic diseases and this association could be due to an increase in circulating inflammatory and oxidative stress biomarkers in the periodontal disease. This study aimed to evaluate the relationship between inflammatory and pro-oxidant markers according to different stages of periodontitis.

METHODS

This cross-sectional study included 70 subjects who were divided into three groups according to periodontitis stage: stage II (n = 22), stage III (n = 30), and stage IV (n = 18). We evaluated periodontal parameters and levels of high-sensitivity C-reactive protein (hsCRP), fibrinogen, and malondialdehyde (MDA) in serum, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in urine.

RESULTS

Serum hsCRP and fibrinogen levels were associated with periodontitis severity, which were higher in stage IV than in stages III and II of periodontitis (p = 0.003 and p = 0.025, respectively). We observed a slight yet insignificant increase in MDA levels related to periodontitis severity. Probing depth and clinical attachment loss were associated with serum fibrinogen and hsCRP levels. However, there were no significant associations between periodontal variables and MDA and 8-OHdG levels.

CONCLUSION

Our data support an association between periodontitis and systemic inflammation, which increases with periodontal disease severity. This indicates the importance of the early diagnosis and treatment of periodontal disease to avoid the development or worsening of systemic inflammatory diseases.

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.

Effects of mechanical strain on periodontal ligament fibroblasts in presence of Aggregatibacter actinomycetemcomitans lysate

PURPOSE

Many adult orthodontic patients suffer from periodontitis, which is caused by oral pathogens such as the gram-negative Aggregatibacter actinomycetemcomitans (Agac). Like orthodontic tooth movement, periodontitis is associated with inflammation and alveolar bone remodelling thereby affecting orthodontic treatment. Interactions of both processes, however, are not sufficiently explored, particularly with regard to oxidative stress.

METHODS

After preincubation with Agac lysate for 24 h periodontal ligament fibroblasts (PDLF) were either stretched or compressed for further 48 h simulating orthodontic forces in vitro. We analysed the expression of genes and proteins involved in the formation of reactive oxygen species (NOX-4, ROS) and nitric oxide (NOS-2), inflammation (TNF, IL-6, PTGS-2) and bone remodelling (OPG, RANKL).

RESULTS

Agac lysate elevated the expression of NOX-4, NOS-2, inflammatory IL-6 and PTGS-2 and the bone-remodelling RANKL/OPG ratio during compressive, but not tensile mechanical strain. Agac lysate stimulated pressure-induced inflammatory signalling, whereas surprisingly ROS formation was reduced. Pressure-induced downregulation of OPG expression was inhibited by Agac lysate.

CONCLUSIONS

Agac lysate impact on the expression of genes and proteins involved in inflammation and bone remodelling as well as ROS formation, when PDLF were subjected to mechanical forces occurring during orthodontic tooth movement.

Self-cascade MoS2 nanozymes for efficient intracellular antioxidation and hepatic fibrosis therapy

Cascade biocatalytic reactions involving multiple antioxidative enzymes are necessary in living cells to regulate cellular metabolism and redox homeostasis. Substantial efforts have been made to construct cascade reactions through engineered enzyme mimics to improve intracellular metabolic flux, especially under pathophysiological conditions. Here, we show that MoS₂ nanozymes exhibit activities of four major cellular cascade antioxidant enzymes, including superoxide dismutase, catalase, peroxidase, and glutathione peroxidase. Meanwhile, MoS₂ nanozymes attenuate electron transfer in cytochrome c/H₂O₂ to ameliorate the inherent antioxidant defense system under stress conditions. Thus, MoS₂ nanozymes function as a self-cascade platform to inhibit intracellular reactive oxygen species (ROS) production by modulating mitochondrial function and scavenging abundant ROS through their intrinsic antioxidant capacity. Density functional theory calculations reveal the underlying mechanisms of the intracellular environment-dependent catalase-like activity of MoS₂ nanozymes. Furthermore, we find that the MoS₂ nanozymes play a cytoprotective role in cells and significantly improve the treatment outcomes in a hepatic fibrosis mouse model. These results demonstrate the ROS-scavenging capacity of a single-component MoS₂ nanozyme-based cascade reaction system and reveal the in-depth mechanism, which may advance the development of nanozyme-based antioxidative agents.

Periodontal ligament stem cells in the periodontitis niche: inseparable interactions and mechanisms

Periodontitis is characterized by the periodontium's pathologic destruction due to the host's overwhelmed inflammation to the dental plaque. The bacterial infections and subsequent host immune responses have shaped a distinct microenvironment, which generally affects resident periodontal ligament stem cells (PDLSCs). Interestingly, recent studies have revealed that impaired PDLSCs may also contribute to the disturbance of periodontal homeostasis. The putative vicious circle underlying the interesting "positive feedback" of PDLSCs in the periodontitis niche remains a hot research topic, whereas the inseparable interactions between resident PDLSCs and the periodontitis niche are still not fully understood. This review provides a microscopic view on the periodontitis progression, especially the quick but delicate immune responses to oral dysbacterial infections. We also summarize the interesting crosstalk of the resident PDLSCs with their surrounding periodontitis niche and potential mechanisms. Particularly, the microenvironment reduces the osteogenic properties of resident PDLSCs, which are closely related to their reparative activity. Reciprocally, these impaired PDLSCs may disrupt the microenvironment by aggravating the host immune responses, promoting aberrant angiogenesis, and facilitating the osteoclastic activity. We further recommend that more in-depth studies are required to elucidate the interactions of PDLSCs with the periodontal microenvironment and provide novel interventions for periodontitis.

Synthetic Hexanucleotides as a Tool to Overcome Excessive Neutrophil Activation Caused by CpG-Containing Oligonucleotides

Mimicking bacterial DNA, synthetic CpG-containing oligodeoxyribonucleotides (CpG-ODNs) have a powerful immunomodulatory potential. Their practical application is mainly associated with the production of vaccines, where they are used as adjuvants, as well as in local antimicrobial therapy. CpG-ODNs act on a wide variety of immune cells, including neutrophilic granulocytes. On the one hand, the stimulatory effect provides both the direct implementation of their antimicrobial and fungicidal mechanisms, and an avalanche-like strengthening of the immune signal due to interaction with other participants in the immune process. On the other hand, hyperactivation of neutrophilic granulocytes can have negative consequences. In particular, the formation of unreasonably high amounts of reactive oxygen species leads to tissue damages and, as a consequence, a spontaneous aggravation and prolongation of the inflammatory process. Under physiological conditions, a large number of DNA fragments are present in inflammation foci: both of microbial and self-tissue origin. We investigated effects of several short modified hexanucleotides on the main indicators of neutrophil activation, as well as their influence on the immunomodulatory activity of known synthetic CpG-ODNs. The results obtained show that short oligonucleotides partially inhibit the prooxidant effect of synthetic CpG-ODNs without significantly affecting the ability of the latter to overcome bacteria-induced pro-survival effects on neutrophilic granulocytes.

Superoxide Dismutase 1 Nanoparticles (Nano-SOD1) as a Potential Drug for the Treatment of Inflammatory Eye Diseases

Inflammatory eye diseases remain the most common clinical problem in ophthalmology. The secondary processes associated with inflammation, such as overproduction of reactive oxygen species (ROS) and exhaustion of the endogenous antioxidant system, frequently lead to tissue degeneration, vision blurring, and even blindness. Antioxidant enzymes, such as copper-zinc superoxide dismutase (SOD1), could serve as potent scavengers of ROS. However, their delivery into the eye compartments represents a major challenge due to the limited ocular penetration. This work presents a new therapeutic modality specifically formulated for the eye on the basis of multilayer polyion complex nanoparticles of SOD1 (Nano-SOD1), which is characterized by appropriate storage stability and pronounced therapeutic effect without side reactions such as eye irritation; acute, chronic, and reproductive toxicity; allergenicity; immunogenicity; mutagenicity even at high doses. The ability of Nano-SOD1 to reduce inflammatory processes in the eye was examined in vivo in rabbits with a model immunogenic uveitis-the inflammation of the inner vascular tract of the eye. It was shown during preclinical studies that topical instillations of Nano-SOD1 were much more effective compared to the free enzyme in decreasing uveitis manifestations. In particular, we noted statistically significant differences in such inflammatory signs in the eye as corneal and conjunctival edema, iris hyperemia, and fibrin clots. Moreover, Nano-SOD1 penetrates into interior eye structures more effectively than SOD itself and retains enzyme activity in the eye for a much longer period of time, decreasing inflammation and restoring antioxidant activity in the eye. Thus, the presented Nano-SOD1 can be considered as a potentially useful therapeutic agent for the treatment of ocular inflammatory disorders.

The bidirectional role of the JAK2/STAT3 signaling pathway and related mechanisms in cerebral ischemia-reperfusion injury

The Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway, a well-conserved and basic intracellular signaling cascade, is mostly inactivated under basal conditions, although it can be phosphorylated under extracellular stimulation; in addition, it can influence the transcription and expression of multiple genes involved in biological processes such as cellular growth, metabolism, differentiation, degradation and angiogenesis. The inflammatory response, apoptosis, oxidative stress and angiogenesis are the main factors involved in the pathogenesis of ischemic stroke. Numerous studies have confirmed that the JAK2/STAT3 axis can be activated rapidly by ischemic stress, which is closely related to the regulation of these important pathological processes. However, different opinions on the specific role of this signaling pathway remain. In this paper, we review and summarize previous studies on the JAK2/STAT3 pathway in ischemic stroke.

Role of NLRP3 inflammasome in COVID-19 and periodontitis: Possible protective effect of melatonin

Daily new information emerges regarding the COVID-19, infection of SARS-CoV-2, which is considered a global pandemic. Angiotensin-converting enzyme 2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) are required to complete the viral invasion pathway and are present in the oral mucosa, gingiva and periodontal pocket. Thus, increasing the likelihood of periodontitis and gingivitis caused by COVID-19. The cytokine storm during COVID-19 similarly arises during periodontal inflammation. Studies have reported that NOD-Like Receptor family pyrin domain-containing 3 (NLRP3) inflammasome is significant in the cytokine storm. Recently, the course of the COVID-19 has been related to the melatonin levels in both COVID-19 and periodontal diseases. It is known that melatonin prevents the activation of NLRP3 inflammasome. In light of these findings, we think that melatonin treatment during COVID-19 or periodontal diseases may prevent the damage seen in periodontal tissues by preventing the activation of NLRP3 inflammasome.

Metabolic activity of hydro-carbon-oxo-borate on a multispecies subgingival periodontal biofilm: a short communication

Objective

This study evaluated the metabolic activity of hydro-carbon-oxo-borate complex (HCOBc) on a multispecies subgingival biofilm as well as its effects on cytotoxicity.

Materials and methods

The subgingival biofilm with 32 species related to periodontitis was formed in the Calgary Biofilm Device (CBD) for 7 days. Two different therapeutic schemes were adopted: (1) treatment with HCOBc, 0.12% chlorhexidine (CHX), and negative control group (without treatment) from day 3 until day 6, two times a day for 1 min each time, totaling 8 treatments and (2) a 24-h treatment on a biofilm grown for 6 days. After 7 days of formation, biofilm metabolic activity was determined by colorimetry assay, and bacterial counts and proportions of complexes were determined by DNA-DNA hybridization. Both substances’ cytotoxicity was evaluated by cell viability (XTT assay) and clonogenic survival assay on ovary epithelial CHO-K1 cells and an osteoblast precursor from calvaria MC3T3-E1 cells.

Results

The first treatment scheme resulted in a significant reduction in biofilm’s metabolic activity by means of 77% by HCOBc and CHX treatments versus negative control. The total count of 11 and 25 species were decreased by treatment with hydro-carbon-oxo-borate complex and CHX, respectively, compared with the group without treatment (p < 0.05), highlighting a reduction in the levels of Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia, and Fusobacterium periodontium. CHX significantly reduced the count of 10 microorganisms compared to the group treated with HCOBc (p < 0.05). HCOBc and CHX significantly decreased the pathogenic red-complex proportion compared with control-treated biofilm, and HCOBc had even a more significant effect on the red complex than CHX had (p ≤ 0.05). For the second treatment scheme, HCOBc complex and CHX significantly decreased 61 and 72% of control biofilms’ metabolic activity and the counts of 27 and 26 species, respectively. HCOBc complex did not significantly affect the proportions of formed biofilms, while CHX significantly reduced red, orange, and yellow complexes. Both substances exhibited similar cytotoxicity results.

Conclusions

This short communication suggested that the HCOBc complex reduced a smaller number of bacterial species when compared to chlorhexidine during subgingival biofilm formation, but it was better than chlorhexidine in reducing red-complex bacterial proportions. Although HCOBc reduced the mature 6-day-old subgingival multispecies biofilms, it did not modify bacterial complexes’ ratios as chlorhexidine did on the biofilms mentioned above. Future in vivo studies are needed to validate these results.

Clinical relevance

HCOBc complex could be used to reduce red-complex periodontal bacterial proportions.

Evaluation of Microcirculation, Cytokine Profile, and Local Antioxidant Protection Indices in Periodontal Health, and Stage II, Stage III Periodontitis

Periodontitis, initiated by the subgingival biofilm and modified by the individual’s inflammatory/immune response, has been associated with vascular dysfunction. To analyze microcirculation indices in periodontal tissues and determine the activity of the enzymatic component of antioxidant defense and humoral immunity factors, a single-blind non-invasive clinical trial was realized. Forty subjects, aged from 30 to 65 years, with moderate to severe chronic periodontitis (chronic generalized periodontitis, CGP) vs. 40 subjects as periodontally healthy were recruited. Information such as capillary diameter, capillary blood flow velocity, concentration of pro- and anti-inflammatory cytokines in serum, vascular endothelial growth factor, and enzymatic component of antioxidant protection were taken. The revealed microcirculatory dysfunctions in patients with CGP clearly demonstrate the progressive disorder of periodontal tissue perfusion and oxygenation, the presence of increased vascular permeability and functional failure of the microvascular system in the lesion. Cytokine profile of CGP patients’ blood serum demonstrated a significant increase of interleukin (IL)-1β, IL-6, tumor necrosis factor α (TNF-α), IL-4 levels as well as statistically significant decrease of IL-1ra, IL-10 concentration. Participants with CGP demonstrated a dominant superiority of IgM and IgG levels. In conclusion, these results contribute to a better understanding of potential correlation between microvascular changes and local and systemic markers of inflammation.

Periodontal Pathogens' strategies disarm neutrophils to promote dysregulated inflammation

Periodontitis is an irreversible, chronic inflammatory disease where inflammophilic pathogenic microbial communities accumulate in the gingival crevice. Neutrophils are a major component of the innate host response against bacterial challenge, and under homeostatic conditions, their microbicidal functions typically protect the host against periodontitis. However, a number of periodontal pathogens developed survival strategies to evade neutrophil microbicidal functions while promoting inflammation, which provides a source of nutrients for bacterial growth. Research on periodontal pathogens has largely focused on a few established species: Tannerella forsythia, Treponema denticola, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis. However, advances in culture-independent techniques have facilitated the identification of new bacterial species in periodontal lesions, such as the two Gram-positive anaerobes, Filifactor alocis and Peptoanaerobacter stomatis, whose characterization of pathogenic potential has not been fully described. Additionally, there is not a full understanding of the pathogenic mechanisms used against neutrophils by organisms that are abundant in periodontal lesions. This presents a substantial barrier to the development of new approaches to prevent or ameliorate the disease. In this review, we first summarize the neutrophil functions affected by the established periodontal pathogens listed above, denoting unknown areas that still merit a closer look. Then, we review the literature on neutrophil functions and the emerging periodontal pathogens, F. alocis and P. stomatis, comparing the effects of the emerging microbes to that of established pathogens, and speculate on the contribution of these putative pathogens to the progression of periodontal disease.

ROS-Scavenging Nanomaterials to Treat Periodontitis

The incidence of periodontitis is very high, and up to 45-50% of people are suffering from periodontitis. Periodontitis is caused by pathogens that invade teeth-supporting tissues such as gingiva, periodontal ligament, and alveolar bone. Pathogens trigger host immune responses characterized by the overproduction of reactive oxygen species (ROS). The development of effective ROS scavengers through nanotechnology has been emerging as a promising strategy for the treatment of periodontitis. Nanomaterial-based antioxidants can effectively scavenge ROS, prevent ROS-mediated tissue damage, and relieve inflammation in periodontitis. This mini-review focuses on the generation of ROS in periodontitis and its molecular mechanism of destroying periodontal tissue. Meanwhile, we summarize the research progress of ROS-scavenging nanomaterials in the treatment of periodontitis and discuss the challenges and prospects of its application.

The Promising Role of Antioxidant Phytochemicals in the Prevention and Treatment of Periodontal Disease via the Inhibition of Oxidative Stress Pathways: Updated Insights

There is growing evidence on the involvement of oxidative stress, which is simply described as the imbalance between oxidants and antioxidants in favor of the former, in the development of periodontal disease that is the most common inflammatory disease in the oral cavity. Thus, the potential of antioxidant phytochemicals as adjunctively preventive and therapeutic agents against the initiation and progression of periodontal disease is a topic of great interest. The current review firstly aims to provide updated insights about the immuno-inflammatory pathway regulated by oxidative stress in periodontal pathology. Then, this work further presents the systemic knowledge of antioxidant phytochemicals, particularly the pharmacological activities, which can be utilized in the prevention and treatment of periodontal disease. Additionally, the challenges and future prospects regarding such a scope are figured out.

Cellular expression of DNA damage/repair and reactive oxygen/nitrogen species in human periodontitis and peri-implantitis lesions

AIM OF THE STUDY

To evaluate differences in the cellular expression of DNA damage/repair and reactive oxygen/nitrogen species between human periodontitis and peri-implantitis lesions.

MATERIAL AND METHODS

40 patients presenting with generalized severe periodontitis and 40 patients with severe peri-implantitis were included. Soft tissue biopsies were collected from diseased sites in conjunction with surgical therapy and prepared for histological analysis. Four regions of interest were identified: the pocket epithelium (PE), the infiltrated connective tissue (ICT), which was divided into one inner area facing the PE (ICT-1) and one outer area (ICT-2). A non-infiltrated connective tissue area (NCT) lateral of the ICT was also selected.

RESULTS

It was demonstrated that the ICT of peri-implantitis specimens was considerably larger and contained significantly larger area proportions and densities of CD68-, MPO- and iNOS-positive cells than that of periodontitis samples. Cellular densities were overall higher in the inner ICT zone lateral of the PE (ICT-1) than in the outer ICT compartment (ICT-2). While the NCT area lateral of the ICT comprised significantly larger proportions and densities of y-H2AX-, iNOS-, NOX2-, MPO- and PAD4/MPO-positive cells in peri-implantitis than in periodontitis sites, a reverse difference was noted for the area proportion and density of 8-OHdG-positive cells in the PE.

CONCLUSIONS

It is suggested that peri-implantitis lesions are associated with an enhanced and upregulated host response and contain larger numbers of neutrophils, macrophages and iNOS-positive cells than periodontitis lesions.

Madecassoside protects retinal pigment epithelial cells against hydrogen peroxide-induced oxidative stress and apoptosis through the activation of Nrf2/HO-1 pathway

Age-related macular degeneration (AMD) is a progressive and degenerative ocular disease associated with oxidative stress. Madecassoside (MADE) is a major bioactive triterpenoid saponin that possesses antioxidative activity. However, the role of MADE in AMD has never been investigated. In the current study, we aimed to evaluate the protective effect of MADE on retinal pigment epithelium (RPE) cells under oxidative stress condition. We used hydrogen peroxide (H2O2) to induce oxidative damage in human RPE cells (ARPE-19 cells). Our results showed that H2O2-caused significant decrease in cell viability and increase in lactate dehydrogenase (LDH) release were dose-dependently attenuated by MADE. MADE treatment also attenuated H2O2-induced reactive oxygen species (ROS) and malondialdehyde (MDA) production in RPE cells. The reduced glutathione (GSH) level and superoxide dismutase (SOD) activity in H2O2-induced ARPE-19 cells were elevated after MADE treatment. MADE also suppressed caspase-3 activity and bax expression, as well as increased bcl-2 expression. Furthermore, H2O2-induced increase in expression levels of HO-1 and nuclear Nrf2 were enhanced by MADE treatment. Finally, knockdown of Nrf2 reversed the protective effects of MADE on H2O2-induced ARPE-19 cells. In conclusion, these findings demonstrated that MADE protected ARPE-19 cells from H2O2-induced oxidative stress and apoptosis by inducing the activation of Nrf2/HO-1 signaling pathway.

TRIM16 protects human periodontal ligament stem cells from oxidative stress-induced damage via activation of PICOT

Periodontitis is a chronic inflammatory disease that result in severe loss of supporting structures and substantial tooth loss. Oxidative stress is tightly involved in the progression of periodontitis. Tripartite Motif 16 (TRIM16) has been identified as a novel regulatory protein in response to oxidative and proteotoxic stresses. The present study aimed to investigate the role of TRIM16 in human periodontal ligament stem cells (hPDLSCs) under oxidative stress. First, we found that the expression of TRIM16 decreased after exposure to H₂O₂. Then TRIM16 overexpression alleviated H₂O₂-induced oxidative stress by enhancing antioxidant capacity and reducing the amount of intracellular reactive oxygen species (ROS) and reactive nitrogen species (RNS). TRIM16 increased cell viability, inhibited cell apoptosis and the depolarization of the mitochondrial membrane potential in hPDLSCs. Furthermore, TRIM16 attenuated H₂O₂-induced suppression of osteogenic differentiation. Mechanistically, TRIM16 promoted the activation of protein kinase C (PKC)-interacting cousin of thioredoxin (PICOT), p-Akt and Nrf2, while knockdown of PICOT reversed TRIM16-mediated ROS resistance and decreased the expression of p-Akt and Nrf2. In conclusion, TRIM16 alleviated oxidative damage in hPDLSCs via the activation of PICOT/Akt/Nrf2 pathway, suggesting that TRIM16 could be a promising target to develop effective therapies for periodontitis.

ROS signaling cascades: dual regulations for osteoclast and osteoblast

Accumulating evidence indicates that intracellular reactive oxygen species (ROS) production is highly involved in bone homeostasis by intervening osteoclast or osteoblast differentiation. Interestingly, ROS that are known as oxidizing agents exert dose-dependent biphasic properties in bone remodeling, including preventing osteoblast activity but accelerating osteoclast resorption. ROS mainly composed of superoxide anion radical, hydroxyl radical, nitric oxide, and two-electron reduction product hydrogen peroxide, which are important components to regulate bone cell metabolism and function in mammal skeleton. These free radicals can be partly produced in bone and boosted in an inflammation state. Although numerous researches have emphasized the impacts of ROS on bone cell biology and verified the mechanism of ROS signaling cascades, the recapitulatory commentary is necessary. In this review article, we particularly focus on the regulation of the intracellular ROS and its potential mechanism impacting on cell-signaling transduction in osteoclast and osteoblast differentiation for preferable understanding the pathogenesis and searching for novel therapeutic protocols for human bone diseases.

Periodontitis is an inflammatory disease of oxidative stress: We should treat it that way

Periodontitis is a highly prevalent disease. As it progresses, it causes serious morbidity in the form of periodontal abscesses and tooth loss and, in the latter stages, pain. It is also now known that periodontitis is strongly associated with several nonoral diseases. Thus, patients with periodontitis are at greater risk for the development and/or exacerbation of diabetes, chronic obstructive pulmonary disease, and cardiovascular diseases, among other conditions. Although it is without question that specific groups of oral bacteria which populate dental plaque play a causative role in the development of periodontitis, it is now thought that once this disease has been triggered, other factors play an equal, and possibly more important, role in its progression, particularly in severe cases or in cases that prove difficult to treat. In this regard, we allude to the host response, specifically the notion that the host, once infected with oral periodontal pathogenic bacteria, will mount a defense response mediated largely through the innate immune system. The most abundant cell type of the innate immune system - polymorphonuclear neutrophils - can, when protecting the host from microbial invasion, mount a response that includes upregulation of proinflammatory cytokines, matrix metalloproteinases, and reactive oxygen species, all of which then contribute to the tissue damage and loss of teeth commonly associated with periodontitis. Of the mechanisms referred to here, we suggest that upregulation of reactive oxygen species might play one of the most important roles in the establishment and progression of periodontitis (as well as in other diseases of inflammation) through the development of oxidative stress. In this overview, we discuss both innate and epigenetic factors (eg, diabetes, smoking) that lead to the development of oxidative stress. This oxidative stress then provides an environment conducive to the destructive processes observed in periodontitis. Therefore, we shall describe some of the fundamental characteristics of oxidative stress and its effects on the periodontium, discuss the diseases and other factors that cause oxidative stress, and, finally, review potentially novel therapeutic approaches for the management (and possibly even the reversal) of periodontitis, which rely on the use of therapies, such as resveratrol and other antioxidants, that provide increased antioxidant activity in the host.

Local promotion of B10 function alleviates experimental periodontitis bone loss through antagonizing RANKL-expressing neutrophils

BACKGROUND

Persistent host immune responses initiated by oral bacteria protect host against infection but may also elicit the process of sustained periodontal inflammation and subsequent alveolar bone loss. Interleukin-10 (IL-10), an anti-inflammatory cytokine, can downregulate pro-inflammatory cytokine and inhibit neutrophil migration in inflammation. IL-10-expressing regulatory B cells (B10) is termed by negatively regulating immune response through IL-10 and are mainly restricted in CD19⁺ CD1d^hi CD5⁺ B cells in mice. Our current study was aimed to explore the effect of locally transferred CD19⁺ CD1d^hi CD5⁺ B cells on inflammation and alveolar bone loss in an experimental periodontitis mouse model.

METHODS

Ligation plus P. gingivalis (Pg) infection was used to induce periodontitis in a mouse model. CD19⁺ CD1d^hi CD5⁺ B cells were sorted by flow cytometry and transferred into the gingivae immediately on the fifth day after ligation. All the mice were sacrificed on day 14 after ligation.

RESULTS

H&E staining showed that inflammatory cell infiltration was significantly reduced by the CD19⁺ CD1d^hi CD5⁺ B cells. Toluidine blue staining showed that the CD19⁺ CD1d^hi CD5⁺ B cells alleviated alveolar bone loss in the ligature/Pg-induced periodontitis in mice. Immunohistochemical staining showed Receptor Activator of NF-KappaB Ligand (RANKL), Interleukin-1β(IL-1β) and Interleukin-17 (IL-17) were decreased after the CD19⁺ CD1d^hi CD5⁺ B cell transfer. Immunofluorescent staining showed that IL-10 was increased while the number of Ly6G⁺ neutrophil and its RANKL production were decreased in gingival tissue.

CONCLUSIONS

These results indicated that locally transferred CD19⁺ CD1d^hi CD5⁺ B cells may alleviate alveolar bone loss through inhibiting pro-inflammatory cytokine expression and RANKL-expressing neutrophils in the periodontitis mouse model.

Select Septate Junction Proteins Direct ROS-Mediated Paracrine Regulation of Drosophila Cardiac Function

Septate junction (SJ) complex proteins act in unison to provide a paracellular barrier and maintain structural integrity. Here, we identify a non-barrier role of two individual SJ proteins, Coracle (Cora) and Kune-kune (Kune). Reactive oxygen species (ROS)-p38 MAPK signaling in non-myocytic pericardial cells (PCs) is important for maintaining normal cardiac physiology in Drosophila. However, the underlying mechanisms remain unknown. We find that in PCs, Cora and Kune are altered in abundance in response to manipulations of ROS-p38 signaling. Genetic analyses establish Cora and Kune as key effectors of ROS-p38 signaling in PCs on proper heart function. We further determine that Cora regulates normal Kune levels in PCs, which in turn modulates normal Kune levels in the cardiomyocytes essential for proper heart function. Our results thereby reveal select SJ proteins Cora and Kune as signaling mediators of the PC-derived ROS regulation of cardiac physiology.

Apical periodontitis induces changes on oxidative stress parameters and increases Na+/K+-ATPase activity in adult rats

OBJECTIVES

Endodontic infection can cause systemic alterations. The involvement of oxidative stress (OS) and transmembrane enzymes compose the pathogenesis of various systemic diseases. However, the relation among apical periodontitis (AP), OS parameters, and Na⁺/K⁺-ATPase (NKA) pump was not reported in the literature. This study evaluated the AP influence on OS parameters and NKA activity in adult rats.

METHODS

Adult male Wistar rats (sixteen weeks old) were randomly assigned to two experimental groups: control (CT group; n = 8) and AP (AP group; n = 9), which was induced in the first right mandibular molar tooth. After 21 days of AP induction, mandibles were dissected for radiographic analysis. In addition, the heart, liver, pancreas, and kidney were collected for analysis of endogenous OS parameters and NKA activity. Data were analyzed by Student's T-test. Values of p < 0.05 were considered statistically significant.

RESULTS

AP presence increased reactive species (RS) generation only in the heart, while the other analyzed organs did not have this parameter modified. Heart and pancreas had a decreased endogenous antioxidant system (catalase activity and vitamin C levels), liver and kidney had an increased one. AP increased NKA activity in the heart, liver, and pancreas, but not in the kidney.

CONCLUSION

The modulation of both endogenous antioxidant defense system and NKA activity in vital organs suggested that alterations in the antioxidant status and cellular electrochemical gradient may be involved in the AP pathophysiology.

Effect of Non-Surgical Periodontal Treatment on Oxidative Stress Markers in Leukocytes and Their Interaction with the Endothelium in Obese Subjects with Periodontitis: A Pilot Study

Aim: The primary objective of this pilot study was to evaluate the effect of non-surgical periodontal treatment. The secondary aim was to evaluate the effect of dietary therapy on both parameters of oxidative stress in leukocytes and leukocyte-endothelial cell interactions in an obese population. Methods: This was a pilot study with a before-and-after design. Forty-nine obese subjects with periodontitis were randomized by means of the minimization method and assigned to one of two groups, one of which underwent dietary therapy while the other did not. All the subjects underwent non-surgical periodontal treatment. We determined periodontal, inflammatory and oxidative stress parameters—total reactive oxygen species (ROS), superoxide production, intracellular Ca²⁺, mitochondrial membrane potential and superoxide dismutase (SOD) activity. We also evaluated interactions between leukocytes and endothelium cells—velocity, rolling flux and adhesion—at baseline and 12 weeks after intervention. Results: Periodontal treatment improved the periodontal health of all the patients, with a reduction in serum retinol-binding protein 4 (RBP4), total superoxide production and cytosolic Ca²⁺ in leukocytes. In the patients undergoing dietary therapy, there were less leukocyte adhesion to the endothelium, an effect that was accompanied by a decrease in TNFα, P-selectin and total ROS and an increase in SOD activity. Conclusions: Whereas non-surgical periodontal treatment induces an improvement in leukocyte homeostasis, dietary therapy as an adjuvant reduces systemic inflammation and increases antioxidant status which, in turn, modulates leukocyte-endothelium dynamics.

Theaflavin-3, 3'-Digallate Suppresses RANKL-Induced Osteoclastogenesis and Attenuates Ovariectomy-Induced Bone Loss in Mice

Theaflavin-3, 3′-digallate (TF3) is extracted from black tea and has strong antioxidant capabilities. The aim of this study was to assess the influences of TF3 on osteoclastogenesis and explore the underlying mechanisms. TF3 efficiently decreased receptor activator of nuclear factor-kappa B ligand (RANKL)-induced osteoclast formation and reactive oxygen species (ROS) generation in a dose-dependent manner. Mechanistically, TF3 reduced ROS generation by activating nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream heme oxygenase-1 (HO-1) and also inhibited the mitogen-activated protein kinases (MAPK) pathway. Moreover, micro-computed tomography (CT) analysis, hematoxylin and eosin (H&E) staining, and TRAP staining of the femurs of C57BL/6J female mice showed that TF3 markedly attenuated bone loss and osteoclastogenesis in mice. Immunofluorescence staining, 2′,7′-dichlorofluorescein diacetate (DCFH-DA) staining, and measurement of the levels of malonaldehyde (MDA) and superoxide dismutase (SOD) revealed that TF3 increased the expression of Nrf2 and decreased the intracellular ROS level in vivo. These findings indicated that TF3 may have the potential to treat osteoporosis and bone diseases related to excessive osteoclastogenesis via inhibiting the intracellular ROS level.

The effects of taxifolin on alveolar bone in experimental periodontitis in rats

OBJECTIVE

This study aimed to evaluate the effect of taxifolin, a powerful antioxidant, on the progression of periodontitis by immunohistochemical and cone-beam computed tomography (CBCT) examination.

DESIGN

This study was performed with 32 rats in four experimental groups: a non-ligated group (Control, n = 8), periodontitis group (Perio, n = 8), periodontitis with 1 mg/kg/day taxifolin group (Taxi-1, n = 8), and periodontitis with 10 mg/kg/day taxifolin group (Taxi-10, n = 8). A ligature-induced experimental periodontitis design was used. All rats were sacrificed at 30 days. Alveolar bone loss was determined by CBCT. Hematoxylin-eosin stained slides were examined. The expression levels of bone morphogenetic protein 2 (BMP-2), osteocalcin (OCN), alkaline phosphatase (ALP), collagen type I (Col 1), Bcl-2, Bax, and receptor activator of NF-κB ligand (RANKL) were determined immunohistochemically.

RESULTS

Both doses of taxifolin showed a decrease in alveolar bone loss. The inflammatory reaction was higher in the Perio group and lower in the taxifolin groups. BMP-2, OCN, ALP, and Col 1 expression were dose-dependently elevated in the taxifolin groups. RANKL immunoexpression decreased with both doses of taxifolin. Bcl-2 expression increased and Bax expression decreased in the taxifolin groups.

CONCLUSION

Taxifolin successfully reduced apoptosis and improved bone formation in alveolar bone in this experimental periodontitis model.

Role of Superoxide Reductase FA796 in Oxidative Stress Resistance in Filifactor alocis

Filifactor alocis, a Gram-positive anaerobic bacterium, is now a proposed diagnostic indicator of periodontal disease. Because the stress response of this bacterium to the oxidative environment of the periodontal pocket may impact its pathogenicity, an understanding of its oxidative stress resistance strategy is vital. Interrogation of the F. alocis genome identified the HMPREF0389_00796 gene that encodes for a putative superoxide reductase (SOR) enzyme. SORs are non-heme, iron-containing enzymes that can catalyze the reduction of superoxide radicals to hydrogen peroxide and are important in the protection against oxidative stress. In this study, we have functionally characterized the putative SOR (FA796) from F. alocis ATCC 35896. The recombinant FA796 protein, which is predicted to be a homotetramer of the 1Fe-SOR class, can reduce superoxide radicals. F. alocis FLL141 (∆FA796::ermF) was significantly more sensitive to oxygen/air exposure compared to the parent strain. Sensitivity correlated with the level of intracellular superoxide radicals. Additionally, the FA796-defective mutant had increased sensitivity to hydrogen peroxide-induced stress, was inhibited in its ability to form biofilm and had reduced survival in epithelial cells. Collectively, these results suggest that the F. alocis SOR protein is a key enzymatic scavenger of superoxide radicals and protects the bacterium from oxidative stress conditions.

Gender Differences in the Levels of Periodontal Destruction, Behavioral Risk Factors and Systemic Oxidative Stress in Ischemic Stroke Patients: A Cohort Pilot Study

Background: Due to the higher frequency of ischemic stroke in men compared to women, we aimed to determine if gender differences exist regarding periodontal status and several plasma biomarkers in patients with a recent large artery atherosclerosis ischemic stroke (IS). Material and methods: Patients with their first IS within less than six weeks who were able to undergo periodontal examinations were evaluated. Demographic data, periodontal status, oxidative stress parameters/plasma antioxidant capacity, and C-reactive protein in patients who suffered a recent large artery atherosclerosis ischemic stroke were reccorded. Results: 93 patients were included in the study. More men were smokers (12/57 vs. 3/36) and consumed alcohol (17/57 vs. 3/36), and more women had higher glycemic values (p = 0.023), total cholesterol (p < 0.001), LDL (low-density lipoprotein)-cholesterol (p = 0.010), and HDL (high-density lipoprotein)-cholesterol (p = 0.005) levels. Significantly more men than women had moderate plus severe periodontal disease (p = 0.018), significantly higher levels of nitric oxide (p = 0.034), and significantly lower levels of total antioxidant capacity (p = 0.028). Conclusions: In this pilot study, men seem to be more prone to oxidative stress and to develop more severe forms of periodontitis among patients with stroke, but the results need validation on a larger sample.

Uncoupling protein-2 regulates M1 macrophage infiltration of gingiva with periodontitis

Periodontitis is an inflammatory disease accompanied by alveolar bone loss. Moreover, M1 macrophages play a critical role in the development of periodontal disease. Uncoupling protein-2 (UCP2) is a mitochondrial transporter protein that controls M1 macrophage activation by modulating reactive oxygen species (ROS) production. We investigated the role of UCP2 in M1 macrophage infiltration in gingival tissues with periodontitis. We found that the expression of UCP2 was upregulated in M1 macrophages infiltrating human periodontal tissues with periodontitis. Macrophage-specific knockout of UCP2 could increase the infiltration of macrophage and exacerbate inflammatory response in a mouse gingiva affected with periodontitis, induced by Porphyromonas gingivalis-LPS (Pg-LPS) injection. The loss of UCP2 may contribute to the enhanced abilities of proliferation, migration, pro-inflammatory cytokine secretion, and ROS production in Pg-LPS-treated macrophages. Our results indicate that UCP2 has an important role in M1 macrophage polarization in the periodontal tissue with periodontitis. It might be helpful to provide theoretical basis for design of new therapeutic strategies for periodontitis.

Interleukin-6, tumor necrosis factor-α, C-reactive protein, and hematological parameters in experimental periodontal disease after β-adrenergic blockade

BACKGROUND

Changes in the levels of C-reactive protein (CRP), tumor necrosis factor α (TNF-α), and interleukin 6 (IL-6) observed during periodontal disease were linked with vascular manifestations. Recent studies showed that the beta-blocker propranolol reduces the pathological parameters associated with certain molecules at sites of bone injury. Hence, in this study, we evaluated the activity of propranolol on hematological parameters and systemic concentrations of inflammatory proteins in a model of experimental periodontitis.

MATERIALS AND METHODS

Periodontal disease was induced in rats. After euthanasia, the number of inflammatory cells in each rat was quantified using histopathological assays. In addition, hematological parameters were quantitated using automated analysers, cytokine levels were determined using an enzyme-linked immunosorbent assay, and CRP levels were determined using a high-sensitivity immunoturbidimetric assay.

RESULTS

Low doses of propranolol suppressed the systemic production of CRP, TNF-α, and IL-6; however, the hematological parameters were not affected.

CONCLUSIONS

β-adrenergic activation indirectly contributes to the pattern of systemic inflammatory molecules observed in periodontal disease. These molecules may initiate cardiovascular diseases as a consequence of periodontitis.

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

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

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.

6-Shogaol Inhibits Advanced Glycation End-Products-Induced IL-6 and ICAM-1 Expression by Regulating Oxidative Responses in Human Gingival Fibroblasts

Advanced glycation end-products (AGEs) cause diabetes mellitus (DM) complications and accumulate more highly in periodontal tissues of patients with periodontitis and DM. AGEs aggravate periodontitis with DM by increasing the expression of inflammation-related factors in periodontal tissues. 6-Shogaol, a major compound in ginger, has anti-inflammatory and anti-oxidative activities. However, the influence of shogaol on DM-associated periodontitis is not well known. In this study, the effects of 6-shogaol on AGEs-induced oxidative and anti-oxidative responses, and IL-6 and ICAM-1 expression in human gingival fibroblasts (HGFs) were investigated. When HGFs were cultured with 6-shogaol and AGEs, the activities of reactive oxygen species (ROS) and antioxidant enzymes (heme oxygenase-1 [HO-1] and NAD(P)H quinone dehydrogenase 1 [NQO1]), and IL-6 and ICAM-1 expressions were investigated. RAGE expression and phosphorylation of MAPKs and NF-κB were examined by western blotting. 6-Shogaol significantly inhibited AGEs-induced ROS activity, and increased HO-1 and NQO1 levels compared with the AGEs-treated cells. The AGEs-stimulated expression levels of receptor of AGE (RAGE), IL-6 and ICAM-1 and the phosphorylation of p38, ERK and p65 were attenuated by 6-shogaol. These results suggested that 6-shogaol inhibits AGEs-induced inflammatory responses by regulating oxidative and anti-oxidative activities and may have protective effects on periodontitis with DM.

Associations between the phenotype and genotype of MnSOD and catalase in periodontal disease

BACKGROUND

Periodontal disease is an inflammatory disease in which pathogenic infections trigger a series of inflammatory responses and redox regulation. The hypothesis of this study was that a host's redox regulation, as modified by genetic polymorphisms, may affect periodontal disease activities (including the plaque index (PlI), bleeding on probing (BOP), and pocket depth (PD)) during periodontal therapy.

METHODS

In total, 175 patients diagnosed with periodontitis were recruited from the Department of Periodontology, Taipei Medical University Hospital. Both saliva samples and clinical measurements (PlI, BOP, and PD) were taken at the baseline and at 1 month after completing treatment. Salivary manganese superoxide dismutase (MnSOD) and catalase, and corresponding genetic polymorphisms (MnSOD, T47C, rs4880 and Catalase, C-262 T, rs1001179) were determined. The extent of change (Δ) of MnSOD or catalase was calculated by subtracting the concentration after completing treatment from that at the baseline.

RESULTS

Subjects who carried the Catalase CC genotype had significantly higher salivary MnSOD or catalase levels. The MnSOD genotype had a significant effect on the percentage of PDs of 4~9 mm (p = 0.02), and salivary ΔMnSOD had a significant effect on the PlI (p = 0.03). The Catalase genotype had a significant effect on the PlI (p = 0.01~0.04), but the effect was not found for the mean PlI or PD. There was a significant interaction between the MnSOD genotype and salivary ΔMnSOD on PDs of 4~9 mm. After adjusting for gender, years of schooling, smoking status, and alcohol consumption, subjects with ΔMnSOD of < 0 μg/ml or Δcatalase of < 0 μg/ml had significantly higher 5.58- or 5.17-fold responses to scaling and root planing treatment.

CONCLUSIONS

The MnSOD T47C genotype interferes with the phenotype of salivary antioxidant level, alters MnSOD levels, and influences the PD recovery. MnSOD and catalase gene polymorphism associated with phenotype expression and susceptibility in periodontal root planing treatment responses.

Reactive Oxygen Species (ROS), Intimal Thickening, and Subclinical Atherosclerotic Disease

Arteriosclerosis causes significant morbidity and mortality worldwide. Central to this process is the development of subclinical non-atherosclerotic intimal lesions before the appearance of pathologic intimal thickening and advanced atherosclerotic plaques. Intimal thickening is associated with several risk factors, including oxidative stress due to reactive oxygen species (ROS), inflammatory cytokines and lipid. The main ROS producing systems in-vivo are reduced nicotinamide dinucleotide phosphate (NADPH) oxidase (NOX). ROS effects are context specific. Exogenous ROS induces apoptosis and senescence, whereas intracellular ROS promotes stem cell differentiation, proliferation, and migration. Lineage tracing studies using murine models of subclinical atherosclerosis have revealed the contributory role of medial smooth muscle cells (SMCs), resident vascular stem cells, circulating bone-marrow progenitors and endothelial cells that undergo endothelial-mesenchymal-transition (EndMT). This review will address the putative physiological and patho-physiological roles of ROS in controlling vascular cell fate and ROS contribution to vascular regeneration and disease progression.

Pathological Characteristics of Periodontal Disease in Patients with Chronic Kidney Disease and Kidney Transplantation

Chronic kidney disease (CKD) is recognized as an irreversible reduction of functional nephrons and leads to an increased risk of various pathological conditions, including cardiovascular disease and neurological disorders, such as coronary artery calcification, hypertension, and stroke. In addition, CKD patients have impaired immunity against bacteria and viruses. Conversely, kidney transplantation (KT) is performed for patients with end-stage renal disease as a renal replacement therapy. Although kidney function is almost normalized by KT, immunosuppressive therapy is essential to maintain kidney allograft function and to prevent rejection. However, these patients are more susceptible to infection due to the immunosuppressive therapy required to maintain kidney allograft function. Thus, both CKD and KT present disadvantages in terms of suppression of immune function. Periodontal disease is defined as a chronic infection and inflammation of oral and periodontal tissues. Periodontal disease is characterized by the destruction of connective tissues of the periodontium and alveolar bone, which may lead to not only local symptoms but also systemic diseases, such as cardiovascular diseases, diabetes, liver disease, chronic obstructive pulmonary disease, and several types of cancer. In addition, the prevalence and severity of periodontal disease are significantly associated with mortality. Many researchers pay special attention to the pathological roles and clinical impact of periodontal disease in patients with CKD or KT. In this review, we provide information regarding important modulators of periodontal disease to better understand the relationship between periodontal disease and CKD and/or KT. Furthermore; we evaluate the impact of periodontal disease on various pathological conditions in patients with CKD and KT. Moreover, pathogens of periodontal disease common to CKD and KT are also discussed. Finally, we examine the importance of periodontal care in these patients. Thus, this review provides a comprehensive overview of the pathological roles and clinical significance of periodontal disease in patients with CKD and KT.

Hydrogen peroxide-based products alter inflammatory and tissue damage-related proteins in the gingival crevicular fluid of healthy volunteers: a randomized trial

Hydrogen peroxide (H₂O₂)-based products are effective in tooth whitening; however, their safety is controversial as they may harm patient tissues/cells. These effects are suggested to be concentration-dependent; nonetheless, to date, there are no reports on H₂O₂-mediated oxidative damage in the gingival tissue, and neither whether this can be detected in gingival crevicular fluid (GCF) samples. We hypothesize that H₂O₂ whitening products may cause collateral oxidative tissue damage following in office application. Therefore, H₂O₂ and nitric oxide (NO) levels were investigated in GCF samples obtained from patients undergoing dental bleaching with H₂O₂ at different concentrations, in a randomized, double-blind, split-mouth clinical trial. A proteomic analysis of these samples was also performed. H₂O₂-based whitening products promoted inflammation which was detected in GCF samples and lasted for longer following 35% H₂O₂ bleaching. This included time-dependent changes in NO levels and in the abundance of proteins associated with NO synthesis, oxidative stress, neutrophil regulation, nucleic acid damage, cell survival and/or tissue regeneration. Overall, H₂O₂-based products used in office promote inflammation irrespective of their concentration. As the inflammation caused by 35% H₂O₂ is longer_, patients may benefit better from using lower concentrations of this bleaching product, as they may result in less tissue damage.

Caffeic acid phenethyl ester protects against oxidative stress and dampens inflammation via heme oxygenase 1

Periodontal disease is associated with chronic oxidative stress and inflammation. Caffeic acid phenethyl ester (CAPE), which is a potent inducer of heme oxygenase 1 (HO1), is a central active component of propolis, and the application of propolis improves periodontal status in diabetic patients. Here, primary murine macrophages were exposed to CAPE. Target gene expression was assessed by whole-genome microarray, RT-PCR and Western blotting. The antioxidative and anti-inflammatory activities of CAPE were examined by exposure of the cells to hydrogen peroxide, saliva and periodontal pathogens. The involvement of HO1 was investigated with the HO1 inhibitor tin protoporphyrin (SnPP) and knockout mice for Nrf2, which is a transcription factor for detoxifying enzymes. CAPE increased HO1 and other heat shock proteins in murine macrophages. A p38 MAPK inhibitor and Nrf2 knockout attenuated CAPE-induced HO1 expression in macrophages. CAPE exerted strong antioxidative activity. Additionally, CAPE reduced the inflammatory response to saliva and periodontal pathogens. Blocking HO1 decreased the antioxidative activity and attenuated the anti-inflammatory activity of CAPE. In conclusion, CAPE exerted its antioxidative effects through the Nrf2-mediated HO1 pathway and its anti-inflammatory effects through NF-κB inhibition. However, preclinical models evaluating the use of CAPE in periodontal inflammation are necessary in future studies.

Propolis, also known as ‘honeybee glue,’ may protect teeth and gums against periodontal disease. In periodontal disease, chronic inflammation and oxidative damage harm gum tissue and lead to tooth loss; propolis has been shown to improve periodontal health for patients with diabetes. Bees make propolis by mixing beeswax, honey, plant resins and their own saliva, and use it to patch honeycomb and prevent growth of microbes in the hive. Reinhard Gruber of the Department of Oral Biology at the Medical University of Vienna and of the Department of Periodontology, University of Bern and co-workers investigated the effects of one of propolis’ active ingredients, caffeic acid phenethyl ester (CAPE), on oxidative stress and inflammation. They found that CAPE reduced oxidative damage and dampened inflammation; further investigation revealed the genetic basis of the beneficial effects, paving the way for future clinical studies. These results may help identify alternative treatments for periodontal disease.

The roles of NADPH oxidase in modulating neutrophil effector responses

Neutrophils are phagocytic innate immune cells essential for killing bacteria via activation of a wide variety of effector responses and generation of large amounts of reactive oxygen species (ROS). Majority of the ROS in neutrophils is generated by activation of the superoxide-generating enzyme nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Independent of their anti-microbial function, NADPH oxidase-derived ROS have emerged as key regulators of host immune responses and neutrophilic inflammation. Data from patients with inherited defects in the NADPH oxidase subunit alleles that ablate its enzyme function as well as mouse models demonstrate profound dysregulation of host inflammatory responses, neutrophil hyper-activation and tissue damage in response to microbial ligands or tissue trauma. A large body of literature now demonstrates how oxidants function as essential signaling molecules that are essential for the regulation of neutrophil responses during priming, degranulation, neutrophil extracellular trap formation, and apoptosis, independent of their role in microbial killing. In this review we summarize how NADPH oxidase-derived oxidants modulate neutrophil function in a cell intrinsic manner and regulate host inflammatory responses. In addition, we summarize studies that have elucidated possible roles of oxidants in neutrophilic responses within the oral mucosa and periodontal disease.

Enhanced In Situ Availability of Aphanizomenon Flos-Aquae Constituents Entrapped in Buccal Films for the Treatment of Oxidative Stress-Related Oral Diseases: Biomechanical Characterization and In Vitro/Ex Vivo Evaluation

In recent years, the key role of oxidative stress in pathogenesis of oral diseases has been emphasized and the use of antioxidant agents has been encouraged. Aphanizomenon flos-aquae (AFA) is a unicellular blue-green alga with antioxidant and anti-inflammatory properties. The aim of this study was the formulation and characterization of mucoadhesive thin layer films loaded with AFA, finalized to the treatment of oxidative stress (OS)-related oral diseases. First, to enhance the bioavailability of AFA constituents, the raw food grade material was appropriately treated by a high frequency homogenization able to disrupt cell walls. Thus, Eudragit^® E100-based buccal films were produced by the solvent casting method, containing 7% and 18% of AFA. The films, characterized by uniformity in thickness, weight, and drug content, showed low swelling degree, good muco-adhesiveness and controlled drug release. The mechanical tests showed elastic moduli of films of almost 5 MPa that is well-suitable for human buccal applications without discomfort, besides biaxial tests highlighted a marked material isotropy. Permeation studies through porcine mucosae demonstrated the ability of films to promote AFA penetration in the tissues, and when sublingually administered, they produced a drug flux up to six-fold higher than an AFA solution. The new formulations represent an interesting alternative for the development of cosmetics and nutraceuticals with a functional appeal containing plant extracts.