Enhanced superoxide production with no change of the antioxidant activity in gingival fluid of patients with chronic adult periodontitis

Oxidative damage biomarkers and antioxidant enzymes in saliva of patients with peri-implant diseases

OBJECTIVES

8-hydroxydeoxyguanosine (8-OHdG) and Malondialdehyde (MDA) are commonly used as markers to evaluate oxidative DNA and Lipid damage in disorders including chronic inflammatory diseases. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) protect tissues against oxidative injury from free oxygen radicals generated by various metabolic processes. The aim of this study was to evaluate 8-OHdG and MDA levels, and SOD and GPx activities in whole saliva of patients with peri-implant diseases.

MATERIALS AND METHODS

A cross-sectional study was conducted on a sum of 60 age gender balanced; peri-implantitis (n = 20), peri-mucositis (n = 20) and healthy (n = 20) individuals. Unstimulated whole saliva samples were collected and to determine the clinical condition of each subject; the plaque index (PI), gingival index (GI), peri-implant probing pocket depth (PIPD), peri-implant presence of bleeding on probing (BOP) (with/without suppuration) and radiographic signs of crestal bone loss (BL) were measured. The salivary 8-OHdG level was measured using the ELISA method. SOD, GPx activities and MDA levels were determined spectrophotometrically.

RESULTS

A total of 60 individuals had evaluations of 318 implants. In comparison to the peri-mucositis and peri-implantitis groups, the healthy group had significantly lower PI and GI scores (p < 0.001). The PIPD value differed amongst the groups, with the peri-implantitis group having the highest value (p < 0.001). Compared to the peri-mucositis and control groups, the peri-implantitis group had a significantly higher BL score (p < 0.001 and p < 0.001, respectively). The peri-implantitis group showed a significantly higher 8-OHdG level (p < 0.001; p < 0.001 respectively) than the peri-mucositis and control groups. Compared to the peri-mucositis and control groups, the peri-implantitis group had a significantly higher MDA level (p < 0.001 and p < 0.001, respectively). The peri-implantitis group had a significantly higher SOD level (p < 0.001 and p < 0.001, respectively) in comparison to the peri-mucositis and control groups. There was no significant difference in GPx levels between the peri-mucositis and control groups (p > 0.05), while the peri-implantitis group had significantly lower GPx levels than the peri-mucositis and control groups (p < 0.001 and p < 0.001, respectively).

CONCLUSIONS

Elevated levels of oxidative stress in saliva may indicate the onset of pathological bone loss surrounding the implant and may be an indication of peri-implantitis.

CLINICAL RELEVANCE

In peri-implant diseases, changes may occur in the levels of 8-OHdG, MDA, SOD and GPx in saliva, which may lead to a deterioration in the oxidant/antioxidant balance.

The Influence of Circadian Rhythm on the Antioxidant Capacity of Saliva in Periodontal Diseases

Background Saliva has a powerful antioxidant activity proposing that it might have a protective role in the oral cavity. It is yet unclear, how circadian rhythm might affect this activity. Objective The main goal of this study was to compare the antioxidant status of saliva in patients with periodontal diseases (PD) to that of healthy people on a diurnal basis. Material and methods A total of 18 periodontal healthy individuals and 18 patients with chronic periodontitis were chosen. Samples of saliva were collected in the morning between 6:00 and 8:00 and in the evening between 6:00 and 8:00 (both stimulated and non-stimulated). The amount of glutathione (GSH), malondialdehyde (MDA), and total antioxidant status (TAS) in the salivary samples were analyzed, and its flow was also assessed. In addition, the scavenging capacity of saliva was tested in three systems generating oxygen free radicals. Results Results showed that GSH and TAS concentrations in the evening saliva of healthy subjects were significantly higher than those in the morning saliva, while MDA levels decreased (p<0.05). Conversely, there was no significant increase in GSH and TAS levels in the evening saliva of subjects with PD, and lipid peroxidation remained constant. On the other hand, the evening saliva of healthy subjects but not of subjects with PD was significantly more potent in scavenging free radicals in vitro than the morning saliva, especially for the superoxide (O2.-) radical (p<0.05). Moreover, scavenging activity was higher in stimulated than non-stimulated saliva. This activity was higher in evening saliva compared to the morning one and greater in healthy subjects compared to patients with PD (p<0.05). Conclusion A balance exists between oxidative stress and antioxidant mechanisms to maintain homeostasis in the oral cavity. This balance is deregulated in patients with PD as their saliva is unable to properly scavenge free radicals that might potentially increase over the day. Antioxidant supplements may be used in accordance with the circadian rhythm to minimize oxidative damage.

Advances of Oxidative Stress Impact in Periodontitis: Biomarkers and Effective Targeting Options

Periodontitis is the most common inflammatory oral disease that affects around 15% of adults and contributes to severe periodontal tissue destruction with subsequent tooth loosening and loss. Among the main pathogenic mechanisms underlying periodontitis, excessive reactive oxygen species production and oxidative stress play a predominant role in inducing both local and systemic damage. Current therapeutic approaches have expanded the conventional methods combined with herbal antioxidant compounds to free radical-scavenging nanomaterials and infrared laser therapy, offering promising pre-clinical evidence in periodontitis management. Herein, we review the pathogenic mechanisms of reactive oxygen species tissue damage, along with recent advances in oxidative stress biomarkers and novel targeting options.

Modification of gingival proteoglycans by reactive oxygen species: potential mechanism of proteoglycan degradation during periodontal diseases

Reactive oxygen species (ROS) overproduction and oxidative stress are increasingly being implicated in the extracellular matrix (ECM) degradation associated with chronic inflammatory conditions, such as periodontal diseases. The present study investigated the effects of ROS exposure on the proteoglycans of gingival tissues, utilizing an in vitro model system comprised of supra-physiological oxidant concentrations, to ascertain whether gingival proteoglycan modification and degradation by ROS contributed to the underlying mechanisms of ECM destruction during active gingivitis. Proteoglycans were purified from ovine gingival tissues and exposed to increasing H₂O₂ concentrations or a hydroxyl radical (·OH) flux for 1 h or 24 h, and ROS effects on proteoglycan core proteins and sulfated glycosaminoglycan (GAG) chains were assessed. ROS were capable of degrading gingival proteoglycans, with ·OH species inducing greater degradative effects than H₂O₂ alone. Degradative effects were particularly manifested as amino acid modification, core protein cleavage, and GAG chain depolymerization. Proteoglycan core proteins were more susceptible to degradation than GAG chains with H₂O₂ alone, although core proteins and GAG chains were both extensively degraded by ·OH species. Proteoglycan exposure to ·OH species for 24 h induced significant core protein amino acid modification, with decreases in glutamate, proline, isoleucine, and leucine; and concomitant increases in serine, glycine, and alanine residues. As clinical reports have previously highlighted proteoglycan core protein degradation during chronic gingivitis, whereas their sulfated GAG chains remain relatively intact, these findings potentially provide further evidence to implicate ROS in the pathogenesis of active gingivitis, complementing the enzymic mechanisms of periodontal tissue destruction already established.

Oxidative Stress and Oral Mucosal Diseases: An Overview

BACKGROUND

Reactive oxygen species (ROS) and free radicals are physiologically produced during cellular metabolism. When their balance is disrupted in favor of ROS, a condition called oxidative stress occurs. Oxidative stress represents a widespread phenomenon involved in several pathological conditions. The aim of the present review was to report current knowledge on oxidative stress related to oral mucosal diseases.

MATERIALS AND METHODS

Articles from 2000 to 2018 were selected for relevance, validity and quality, from results obtained in PubMed, MEDLINE and Google Scholar using the following search terms: oxidative stress and oral lichen, oral pemphigus, aphthous stomatitis, oral leukoplakia, oral cancer, oral squamous cell carcinoma and oral carcinoma. All articles were independently screened for eligibility by the authors.

RESULTS

This narrative review integrates extensive information from all relevant published studies focusing on oxidative stress in oral mucosal diseases. We outline the pathogenetic function of oxidative stress in the most frequent inflammatory, potentially malignant and malignant diseases of the oral mucosa and provide detailed findings from human research.

CONCLUSION

Although variability in findings between individual studies exists, it justifies the conclusion that oxidative stress is a significant process in the oral mucosal diseases pathogenesis.

Effects of Melatonin and Its Underlying Mechanism on Ethanol-Stimulated Senescence and Osteoclastic Differentiation in Human Periodontal Ligament Cells and Cementoblasts

The present study evaluated the protective effects of melatonin in ethanol (EtOH)-induced senescence and osteoclastic differentiation in human periodontal ligament cells (HPDLCs) and cementoblasts and the underlying mechanism. EtOH increased senescence activity, levels of reactive oxygen species (ROS) and the expression of cell cycle regulators (p53, p21 and p16) and senescence-associated secretory phenotype (SASP) genes (interleukin [IL]-1β, IL-6, IL-8 and tumor necrosis factor-α) in HPDLCs and cementoblasts. Melatonin inhibited EtOH-induced senescence and the production of ROS as well as the increased expression of cell cycle regulators and SASP genes. However, it recovered EtOH-suppressed osteoblastic/cementoblastic differentiation, as evidenced by alkaline phosphatase activity, alizarin staining and mRNA expression levels of Runt-related transcription factor 2 (Runx2) and osteoblastic and cementoblastic markers (glucose transporter 1 and cementum-derived protein-32) in HPDLCs and cementoblasts. Moreover, it inhibited EtOH-induced osteoclastic differentiation in mouse bone marrow⁻derived macrophages (BMMs). Inhibition of protein never in mitosis gene A interacting-1 (PIN1) by juglone or small interfering RNA reversed the effects of melatonin on EtOH-mediated senescence as well as osteoblastic and osteoclastic differentiation. Melatonin blocked EtOH-induced activation of mammalian target of rapamycin (mTOR), AMP-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK) and Nuclear factor of activated T-cells (NFAT) c-1 pathways, which was reversed by inhibition of PIN1. This is the first study to show the protective effects of melatonin on senescence-like phenotypes and osteoclastic differentiation induced by oxidative stress in HPDLCs and cementoblasts through the PIN1 pathway.

Antioxidant enzymes in periodontitis

Periodontitis is basically an inflammatory disease initiated by the subgingival biofilm and modified by the individual's aberrant inflammatory/immune response. Various studies have pointed toward the role of oxidative stress in periodontitis. As the reactive oxygen species and antioxidants are in dynamic equilibrium, any disturbance in one would lead to changes in the other. As studying, individual antioxidants is a vast field, this review focuses on the role of antioxidant enzymes in periodontitis and in other related systemic conditions. It is highlighted that oxidative stress may be the missing link in these associations of periodontitis and other conditions. Also, the antioxidant enzymes may be considered a useful biomarker for periodontal diseases and antioxidant supplementation may be of help to reduce the burden of periodontal destruction without having much extra effort.

Nuclear Factor Erythroid 2-Related Factor 2 Down-Regulation in Oral Neutrophils Is Associated with Periodontal Oxidative Damage and Severe Chronic Periodontitis

The balance between reactive oxygen species and antioxidants plays an important role in periodontal health. We previously demonstrated that high reactive oxygen species production by oral polymorphonuclear neutrophils (oPMNs) in chronic periodontitis (CP) refractory to conventional therapy is associated with severe destruction of periodontium. Herein, we show that inhibition of antioxidant production through down-regulation of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in oPMN, despite enhanced recruitment in the oral cavity, is associated with severe CP. Twenty-four genes in the Nrf2-mediated oxidative stress response pathway were down-regulated in PMNs of diseased patients. Downstream of Nrf2, levels of oPMN superoxide dismutase 1 and catalase were decreased in severe CP, despite increased recruitment. Nrf2(-/-) mice had more severe loss of periodontium in response to periodontitis-inducing subgingival ligatures compared with wild-types. Levels of 8-hydroxy-deoxyguanosine were increased in periodontal lesions of Nrf2(-/-) mice, indicating high oxidative damage. We report, for the first time, Nrf2 pathway down-regulation in oPMNs of patients with severe CP. PMNs of CP patients may be primed for low antioxidant response in the context of high recruitment in the oral cavity, resulting in increased oxidative tissue damage.

Reactive oxygen species in periodontitis

Recent epidemiological studies reveal that more than two-third of the world's population suffers from one of the chronic forms of periodontal disease. The primary etiological agent of this inflammatory disease is a polymicrobial complex, predominantly Gram negative anaerobic or facultative bacteria within the sub-gingival biofilm. These bacterial species initiate the production of various cytokines such as interleukin-8 and TNF-α, further causing an increase in number and activity of polymorphonucleocytes (PMN) along with these cytokines, PMNs also produce reactive oxygen species (ROS) superoxide via the respiratory burst mechanism as the part of the defence response to infection. ROS just like the interleukins have deleterious effects on tissue cells when produced in excess. To counter the harmful effects of ROS, human body has its own defence mechanisms to eliminate them as soon as they are formed. The aim of this review is to focus on the role of different free radicals, ROS, and antioxidants in the pathophysiology of periodontal tissue destruction.

Impact of iron deficiency anemia on chronic periodontitis and superoxide dismutase activity: a cross-sectional study

PURPOSE

Both chronic periodontitis (CP) and iron deficiency anemia (IDA) induce oxidative stress in the body and cause an imbalance between reactive oxygen species and antioxidants, such as superoxide dismutase (SOD). This study explored the SOD enzyme activity of saliva and serum in CP patients with and without IDA and analyzed the impact of IDA on CP.

METHODS

A total of 82 patients were divided into four groups: control group (CG, 22), periodontally healthy IDA patients (IDA-PH, 20), CP patients (CP, 20), and IDA patients with CP (IDA-CP, 20). After clinical measurements and samplings, serum and salivary SOD levels were determined using an SOD assay kit.

RESULTS

IDA-CP patients exhibited a higher gingival index, bleeding on probing, probing pocket depth, and percentage (%) of sites with a clinical attachment loss (CAL) of ≥6 mm (P<0.008) than CP patients. The mean salivary and serum SOD levels were significantly lower in the IDA-PH, CP, and IDA-CP patients than in the CG group (P<0.008). A significant positive correlation between salivary and serum SOD activity was observed in IDA (P<0.05). Furthermore, serum and salivary SOD levels were significantly and negatively correlated with all periodontal parameters including the percentage of sites with CAL of 4-5 and ≥6 mm (P<0.05) except the significant correlation between salivary SOD activity and mean CAL and the percentage of sites with CAL of 4-5 mm (P>0.05) in these patients.

CONCLUSIONS

Within the limits of this study, it may be suggested that IDA patients with chronic periodontitis have more periodontal breakdowns than patients with chronic periodontitis. Serum and salivary SOD activity levels were lower in the IDA-PH, CP and IDA-CP groups than in the CG. Iron deficiency anemia influenced the serum SOD activity but did not seem to affect the salivary SOD activity in these patients.

A comparative evaluation of whole blood total antioxidant capacity using a novel nitroblue tetrazolium reduction test in patients with periodontitis and healthy subjects: A randomized, controlled trial

The investigation of disease-related oxidant-antioxidant imbalance is difficult due to the limited availability of specific biomarkers of oxidative stress, and the fact that measurement of individual antioxidant may give misleading picture because antioxidants work in concert through chain breaking reactions. Therefore, analysis of total antioxidant capacity may be the most relevant investigation. As the total blood is continuously exposed to oxidative stress, the aim of the current study was to investigate total blood antioxidant capacity in healthy and periodontitis patients by using novel Nitroblue Tetrazolium reduction test. The study was conducted on 30 non-smoking volunteers with age ranging between 18-40 years. They were categorized into two groups; chronic periodontitis group and healthy group, respectively. Total antioxidant capacity in whole blood was assessed using Nitroblue Tetrazolium reduction test. Results of the present study has shown that the total antioxidant capacity in whole blood in patients with periodontitis was significantly (P<0.005) lower than in control subjects. The reduced total blood antioxidant status in periodontitis subjects warrants further investigation as it may provide a mechanistic link between periodontal disease and several other free radical-associated chronic inflammatory diseases.

Oxidative stress caused by a low concentration of hydrogen peroxide induces senescence-like changes in mouse gingival fibroblasts

Periodontal tissue deteriorates under persistent oxidative stress induced by inflammatory reactions in the microflora of the oral cavity. This study aimed to evaluate the cellular properties of mouse gingival fibroblasts (MGFs) in the presence of oxidative stress. MGFs from 10-, 30- and 52-week-old mice were used to evaluate the changes in the cellular properties with aging. The study investigated the effects of oxidative stress on the cellular properties of MGFs from 10-week-old mice. The expression of p53, p21 and murine double minute 2 (Mdm2) in the MGFs in response to oxidative stress was also examined. By day 8, the number of MGFs increased in culture. However, the increase was markedly lower in MGFs derived from aged mice. Oxidative stress due to hydrogen peroxide (H2O2)-induced morphological changes characterized by a round shape with enlarged nuclei and expanded cytoplasm. The cell number of MGFs was decreased subsequent to treatment with 50 µM or a higher concentration of H₂O₂. MGFs treated with H₂O₂ at 20 µM showed a similar cell growth curve as the one seen in 52-week-old mice. Phosphorylated p53 protein was increased in MGFs subsequent to treatment with 20 µM H2O2, along with an upregulated transcription of p21 and Mdm2 mRNAs. These results suggest that treatment with a lower concentration of H₂O₂ in MGFs induces cell cycle arrest, resulting in stress-induced premature senescence, possibly correlated with the development of periodontal diseases.

Refractory periodontitis population characterized by a hyperactive oral neutrophil phenotype

BACKGROUND

Neutrophils, in addition to being the primary protective component of the innate immune system, also contribute to periodontal destruction through production of reactive oxygen species (ROS), which cause damage to connective tissues and extracellular matrix after neutrophil activation. We have previously shown that hyperactive neutrophils are present in peripheral blood samples of patients diagnosed with refractory periodontitis. To test the hypothesis that oral neutrophil hyperactivity is related to periodontal disease severity, we used a flow cytometric approach to isolate and analyze oral neutrophil ROS (oROS) production in a refractory periodontal disease patient population.

METHODS

Oral rinse samples and venous blood were obtained from 13 patients diagnosed with refractory periodontitis. After isolation of neutrophils from both samples, dihydrorhodamine 123 was used as a fluorescent probe for phorbol 12-myristate 13-acetate-mediated ROS production as assessed through flow cytometry. For each patient, oROS production levels were expressed as a percentage of their baseline to maximal peripheral blood neutrophil ROS production range.

RESULTS

Two distinct groups of refractory patients were identified based on levels of phorbol 12-myristate 13-acetate-stimulated oROS production. The patient group with high oROS production had significantly more clinical attachment loss (AL) compared to the patient group with low oROS production.

CONCLUSIONS

Our findings demonstrate that a group of refractory patients with increased clinical AL present a hyperactive oral neutrophil phenotype characterized by increased potential for ROS production. Identification of this exaggerated oral neutrophil phenotype could allow clinicians to identify which patients are more susceptible to rapid disease progression.

Total antioxidant capacity and superoxide dismutase activity levels in serum and gingival crevicular fluid in pregnant women with chronic periodontitis

BACKGROUND

There is evidence of reduced antioxidant (AO) defense in periodontitis and pregnancy and adverse interactions between periodontitis and pregnancy.

METHODS

In this study, serum and gingival crevicular fluid (GCF) total AO capacity (TAOC) and superoxide dismutase (SOD) enzyme concentrations in pregnant patients with chronic periodontitis (CP) were compared to those in non-pregnant patients. Periodontal examinations were performed and GCF/serum samples were obtained from 33 pregnant patients with CP (PCP), 18 pregnant patients with gingivitis (PG), and 21 periodontally healthy pregnant controls (P-controls), monitored in the first and third trimesters; 27 non-pregnant women with CP; and 25 non-pregnant control women. The concentrations of TAOC (automated measurement method) and SOD (spectrophotometric method) were determined.

RESULTS

Periodontal parameters were higher in pregnant patients versus non-pregnant patients and in the CP group compared to controls, whereas TAOC and SOD concentrations were lower (P <0.05). All parameters, except plaque index, increased in pregnant subjects in the third trimester compared to the first trimester, whereas TAOC and SOD levels decreased (P <0.05). Periodontal parameters were highest and TAOC and SOD levels were lowest in the PCP group in the third trimester (P <0.05).

CONCLUSIONS

Systemic and local GCF AO levels decreased in pregnancy and periodontitis, and AO defense reached the lowest levels in the last phase of pregnancy, whereas periodontal status deteriorated. These results suggest that reduced AO capacity may be associated with adverse periodontitis-pregnancy interactions, and each situation can be a provocative risk factor for the other.

Total antioxidant status and 8-hydroxy-2'-deoxyguanosine levels in gingival and peripheral blood of periodontitis patients

INTRODUCTION

The aim of this study was to determine 8-OHdG concentration as a biomarker of oxidant-induced DNA damage and to assess total antioxidant status (TAS) in gingival and peripheral blood during periodontal lesion.

MATERIALS AND METHODS

The study included 56 untreated periodontitis patients (26 with aggressive periodontitis, and 30 with chronic periodontitis (CP). The control group consisted of 25 healthy volunteers without pathological changes in the periodontium. Competitive ELISA was used to measure 8-OHdG. A colorimetric method based on the reduction of ABTSo+ radical cation generation was used to measure TAS.

RESULTS

Significantly higher 8-OHdG concentrations were detected in the gingival blood in both groups of patients with periodontitis than in the control group. Subjects with CP had significantly decreased TAS levels in the gingival blood compared with the control group. A significantly decreased TAS level in the peripheral blood in both patient groups compared with the control group was found. Significant positive correlation between TAS levels in venous and gingival blood in all the periodontitis patients and in the CP group was observed.

CONCLUSIONS

The oxidative burst in periodontitis may lead to significant local damage to nucleic acids. The significantly decreased TAS level in the gingival blood of CP patients compared with the healthy subjects suggests the possibility of a significant decrease in local antioxidant system capacity during the course of periodontitis. The decreased TAS level in the peripheral blood in the group of all patients with periodontitis may be one of the pathogenic mechanisms underlying the links between periodontal disease and several systemic diseases for which periodontitis is regarded as a independent risk factor.

Hyperactivity and reactivity of peripheral blood neutrophils in chronic periodontitis

Some evidence exists that peripheral neutrophils from patients with chronic periodontitis generate higher levels of reactive oxygen species (ROS) after Fcgamma-receptor stimulation than those from healthy controls. We hypothesized that peripheral neutrophils in periodontitis also show both hyper-reactivity to plaque organisms and hyperactivity in terms of baseline, unstimulated generation and release of ROS. Peripheral neutrophils from chronic periodontitis patients and age/sex/smoking-matched healthy controls (18 pairs) were assayed for total ROS generation and extracellular ROS release, with and without stimulation (Fcgamma-receptor and Fusobacterium nucleatum), using luminol and isoluminol chemiluminescence. Assays were performed with and without priming with Escherichia coli lipopolysaccharide (LPS) and granulocyte-macrophage colony-stimulating factor (GM-CSF). Phox gene expression (p22, p47, p67, gp91) was investigated using reverse transcription-polymerase chain reaction (RT-PCR). Neutrophils from patients produced higher mean levels of ROS in all assays. Total generation and extracellular release of ROS by patients' cells were significantly greater than those from controls after FcgammaR-stimulation, with (P = 0.023) and without (P < or = 0.023) priming with GM-CSF. Differences in unstimulated total ROS generation were not significant. By contrast, patients' cells demonstrated greater baseline, extracellular ROS release than those from controls (P = 0.004). This difference was maintained after priming with LPS (P = 0.028) but not GM-CSF (P = 0.217). Phox gene expression was similar in patient and control cells at baseline and stimulation with F. nucleatum (3 h) consistently reduced gp91(PHOX) transcripts. Our data demonstrate that peripheral neutrophils from periodontitis patients exhibit hyper-reactivity following stimulation (Fcgamma-receptor and F. nucleatum) and hyperactivity in terms of excess ROS release in the absence of exogenous stimulation. This hyperactive/-reactive neutrophil phenotype is not associated with elevated phox gene expression.

Characterization of the antioxidant profile of human saliva in peri-implant health and disease

OBJECTIVES

Peri-implant disease is considered to be an inflammatory disease, but many aspects of its pathogenesis remain unknown. At present, peri-implant disease is considered to be initiated and perpetuated by a small group of predominantly Gram-negative, anaerobic, or micro-aerophilic bacteria that colonize the subgingival area. Bacteria cause the observed tissue destruction directly by toxic products and indirectly by activating host defence systems, i.e. inflammation. A variety of molecular species appears in the inflamed tissues, among them are reactive species such as free radicals and reactive oxygen species (ROS). The purpose of this study was to assess levels of various antioxidants in saliva to identify differences between the saliva of patients with healthy peri-implant tissues and patients with peri-implant disease, and to examine whether the whole saliva of those with peri-implant disease conditions might have lower levels of antioxidants than that of healthy individuals.

MATERIALS AND METHODS

Thirty healthy adult volunteers (14 men and 16 women) with implant-supported overdentures (Ankylos Biofunctional Implants) were selected from the group of patients from Tallinn Dental Clinic. Biochemical and clinical parameters evaluated were the following ones: the levels of urate, ascorbate, myeloperoxidase in saliva, total antioxidant status of saliva, pocket probing depth (mm), gingival index (0, 1, 2, or 3), and bleeding on probing (0 or 1).

RESULTS AND CONCLUSION

Total antioxidant status (TAS) of saliva and concentration of uric acid and ascorbate, which are the main salivary antioxidants, are significantly decreased in patients with peri-implant disease. TAS in healthy subjects was 0.41+/-0.10 for resting saliva and 0.31+/-0.09 for stimulated saliva; in diseased subjects TAS was 0.19+/-0.07 and 0.12+/-0.03, respectively. In healthy subjects, the concentration of urate was 307.2+/-78.06 microM/l in resting saliva and 241.5+/-89.09 microM/l in stimulated saliva. In diseased patients, the concentration of urate was 120+/-36.13 and 91.60+/-39.35 microM/l, respectively. The concentration of ascorbate did not differ in resting and stimulated saliva. In healthy subjects, it was 2.79+/-0.81 mg/l and in diseased subjects, it was 1.54+/-0.30 mg/l. This may indicate that excessive ROS production in peri-implant disease is leading to the situation of excessive oxidative stress, which may be an important factor contributing the destruction of peri-implant tissues. The importance of these findings may be the better understanding of the processes involved in the pathogenesis of peri-implant disease and that the treatment of peri-implant disease may involve adjuvant anti-oxidants supplementation together with cumulative interceptive supportive therapy concept introduced by Mombelli & Lang.

Total antioxidant capacity and superoxide dismutase activity levels in serum and gingival crevicular fluid in post-menopausal women with chronic periodontitis

OBJECTIVES

Menopause has been linked with oxidative stress and decreased antioxidant (AO) defence. A connection has been established between menopause and certain periodontal conditions. The objective of this study is to compare serum and gingival crevicular fluid (GCF) total antioxidant capacity (TAOC) and superoxide dismutase (SOD) concentrations in post-menopausal patients with chronic periodontitis (PMCP) with those of pre-menopausal chronic periodontitis patients (CP).

MATERIAL AND METHODS

Thirty-two PMCP patients, 31 CP patients, 25 post-menopausal periodontally healthy controls (PMPH) and 26 pre-menopausal controls (PH) were studied. After clinical measurements and samplings, serum and GCF TAOC and SOD concentrations were established in turn using an automated TAOC assay and spectrophotometric end point measurement. The results were analysed statistically.

RESULTS

Serum and GCF TAOC and SOD concentrations were significantly lower in menopause and periodontitis (p<0.05). The lowest values were in the PMCP group, whereas the highest values were in the PH group. While the effect of menopause was more evident in serum antioxidant analysis, the effect of periodontitis was observed to be more apparent in GCF.

CONCLUSIONS

A decrease in systemic and local AO defence was observed owing to both menopause and periodontitis. The lowest AO values in the PMCP group suggest that menopause may be a risk factor for periodontitis.

Lipid peroxidation: a possible role in the induction and progression of chronic periodontitis

OBJECTIVES

Reactive oxygen species (ROS) are implicated in the destruction of the periodontium during inflammatory periodontal diseases. The imbalance in oxidant/antioxidant activity may be a key factor in the damaging effects of ROS. This study aimed to determine the lipid peroxidation levels in gingival crevicular fluid and saliva, and glutathione (GSH) and glutathione peroxidase (GPx) in saliva in patients with chronic periodontitis.

METHODS

Gingival crevicular fluid and saliva were collected from 13 patients and 9 healthy control subjects during the preliminary study, and from 21 patients during the subsequent study. Lipid peroxidation level, GSH level and GPx activity were determined by spectrophotometric assay.

RESULTS

The preliminary study found that when comparing patients to healthy controls, the gingival crevicular fluid samples produced the following results, respectively: higher lipid peroxidation concentration (microm) (by sites: 167.55 vs. 53.71, p < 0.0001; by subjects: 151.99 vs. 50.66, p < 0.005) and total amount (pmol) (by sites: 93.02 vs. 8.47, p < 0.0001, by subjects: 80.44 vs. 7.84, p < 0.0005). In saliva samples, lower GSH concentration (microm) (373.04 vs. 606.67, p < 0.05), higher lipid peroxidation concentration (microm) (0.66 vs. 0.13, p < 0.0005), and no difference in GPx activity were found in patients than in those of healthy controls. The subsequent study showed statistically significant (p < 0.05) improvement of clinical periodontal parameters (plaque index, gingival index, probing attachment level, probing pocket depth and gingival crevicular fluid volume), decreases in gingival crevicular fluid lipid peroxidation levels (concentration and total amount) at the sites after the completion of phase 1 periodontal treatment. Similarly, the periodontal treatment resulted in a significant decrease of lipid peroxidation concentrations (p < 0.05), increase in GSH concentration (p < 0.001), and no change in GPx activity in saliva samples.

CONCLUSION

The increased levels of lipid peroxidation may play a role in the inflammation and destruction of the periodontium in periodontitis.

Anti-oxidant therapy: does it have a role in the treatment of human disease?

Free radical oxidative stress has been implicated in the pathogenesis of a variety of human diseases. Natural anti-oxidant defences have also been found to be defective in many of the same diseases. Many researchers have concluded that, if the imbalance between the oxidative stresses and anti-oxidant defence can be corrected by supplementing natural anti-oxidant defences, it may be possible to prevent or retard disease progression. Potential anti-oxidant therapies include natural anti-oxidant enzymes and vitamins or synthetic agents with anti-oxidant activity. Diseases where anti-oxidant therapy may be beneficial can be divided into those involving acute intervention, such as reperfusion injury or inflammation, and those involving chronic preventative therapy, such as atherosclerosis, carcinogenesis and diabetic vascular disease. The pharmaceutical considerations are different in each case. The principles guiding the development, use and assessment of anti-oxidant therapies are discussed in this review.

Analysis of superoxide dismutase activity levels in gingiva and gingival crevicular fluid in patients with chronic periodontitis and periodontally healthy controls

OBJECTIVES

Superoxide dismutase (SOD) is an antioxidant enzyme that acts against superoxide, an oxygen radical, released in inflammatory pathways and causes connective tissue breakdown. In this study, SOD activities in gingiva and gingival crevicular fluid (GCF) from patients with chronic periodontitis (CP) and periodontally healthy controls were compared.

MATERIAL AND METHODS

Twenty-six CP patients and 18 controls were studied. In patients, teeth with moderate-to-severe periodontal breakdown and > or =5 mm pockets that required full-thickness flap surgery in the right or left maxillary quadrant, and in controls, teeth scheduled for extraction for orthodontic reasons were studied. After the clinical measurements (probing depth, clinical attachment level, gingival index, gingival bleeding index, plaque index), GCF samples were collected. Tissue samples were harvested from the same teeth, during flap operation in patients and immediately after tooth extraction in controls. SOD activities were spectrophotometrically assayed. The results were statistically analysed.

RESULTS

Gingival SOD activity was significantly higher in the CP group than in controls (p<0.05). No significant difference was found in GCF SOD activity between the groups (p>0.05). Correlations between gingival and GCF SOD activities were not statistically significant in CP and control groups (p>0.05).

CONCLUSION

In CP, SOD activity seems to increase in gingiva, probably as a result of a higher need for SOD activity and protection in gingiva in CP than in periodontal health, while not significantly changing in GCF, suggesting a weak SOD activity in GCF in periodontal disease state. The weak correlation between gingival and GCF SOD activities suggests distinct actions of these SODs.

Measurement of total antioxidant capacity in gingival crevicular fluid and serum in dogs with periodontal disease

OBJECTIVE

To determine whether gingival crevicular fluid (GCF) and serum total antioxidant capacities (TACs) correlate with the degree of severity of periodontal disease in dogs.

ANIMALS

41 Toy and Miniature Poodles.

PROCEDURES

After assessment of the degree of severity of naturally occurring periodontitis, GCF samples from both maxillary fourth premolars and a blood sample were collected from each dog. The condition of the periodontium of the entire dentition and at each site of GCF collection was recorded. Clinical parameters assessed included plaque index, gingival index, and probing depth. Radiographic analysis of alveolar bone level was also performed. Total antioxidant capacity was measured in GCF and serum samples by use of a commercial kit.

RESULTS

Dogs with gingivitis and minimal periodontitis had significantly higher TAC in GCF than dogs with advanced periodontitis. Bivariate regression analysis revealed significant negative correlations between TAC in GCF and clinical parameters and age. The TAC in serum was significantly negatively correlated with the degree of gingival inflammation but was not significantly correlated with age.

CONCLUSIONS AND CLINICAL RELEVANCE

TAC in GCF is related to the degree of severity of periodontal disease in dogs. This is likely the result of release of reactive oxygen species by activated phagocytes and fibroblasts in the inflamed periodontal tissues. The results of our study suggest that the local delivery of antioxidants may be a useful adjunctive treatment for periodontitis in dogs.

Comparison of oxidative stress biomarker profiles between acute and chronic wound environments

Increasing evidence implicates excessive reactive oxygen species (ROS) generation and ROS-derived degradation products in the pathogenesis of many skin diseases. While numerous attempts have been made to identify prognostic biomarkers of wound healing in skin, these have met with limited success. This study examined the profiles of various oxidative stress biomarkers, namely total protein carbonyl content (from protein oxidation), malondialdehyde content (from lipid peroxidation), and the total antioxidant capacities, in acute wound fluid (n= 10) and chronic wound fluid (n= 12), using a rapid, noninvasive collection technique. Protein carbonyl content was quantified spectrophotometrically and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis/Western blotting, following 2,4-dinitrophenylhydrazine derivitization. Malondialdehyde levels were similarly quantified, following N-methyl-2-phenylindole derivitization. Total antioxidant capacity was determined via wound fluid inhibition of cytochrome C reduction by a superoxide radical flux. Acute wound fluid contained higher protein carbonyl content than chronic wound fluid, particularly evident following sodium dodecyl sulfate-polyacrylamide gel electrophoresis/Western blot analysis under nonreducing and reducing conditions (p < 0.001 and p < 0.02, respectively), related to significantly higher protein levels (p = 0.0005) in acute wound fluid. Human serum albumin ( approximately 66 kDa) was identified as the most prominent protein oxidized in both acute and chronic wound fluid, which may contribute to the reduced albumin and total protein levels in chronic wound fluid. No significant difference (p > 0.1) in malondialdehyde levels or total antioxidant capacities were determined between acute and chronic wound fluids, although chronic wound fluid exhibited significantly higher total antioxidant capacities (p < 0.005), accounting for variations in wound fluid protein content. These findings suggest an adaptation in the antioxidant profiles of chronic wound fluid to counteract the loss of consumed antioxidants in the chronic wound environment. This study highlights the roles of ROS/antioxidants in skin wound healing, their possible involvement in chronic wounds and the potential value of ROS-induced biomarkers in wound healing prognosis.

Local and systemic total antioxidant capacity in periodontitis and health

BACKGROUND

The involvement of reactive oxygen species (ROS) in periodontal pathology is unclear but will be modulated by in vivo antioxidant defence systems. The aim of this cross-sectional study was to determine both local (saliva and gingival crevicular fluid (GCF) and peripheral (plasma and serum) antioxidant capacity in periodontal health and disease.

MATERIALS AND METHODS

Twenty non-smoking volunteers with chronic periodontitis were sampled together with twenty age- and sex-matched, non-smoking controls. After overnight fasting, saliva (whole unstimulated and stimulated) and blood were collected. Total antioxidant capacity (TAOC) was determined using a previously reported enhanced chemiluminescence method.

RESULTS

GCF antioxidant concentration was significantly lower (p<0.001) in periodontitis subjects compared to healthy controls. Although mean levels of peripheral and salivary TAOC were also lower in periodontitis the difference was only significant for plasma (p<0.05). Healthy subjects' GCF antioxidant concentration was significantly greater than paired serum or plasma (p<0.001). Data stratified for gender did not alter the findings and a male bias was revealed in all clinical samples except GCF.

CONCLUSIONS

These findings suggest that the antioxidant capacity of GCF is both qualitatively and quantitatively distinct from that of saliva, plasma and serum. Whether changes in the GCF compartment in periodontitis reflect predisposition to or the results of ROS-mediated damage remains unclear. Reduced plasma total antioxidant defence could result from low-grade systemic inflammation induced by the host response to periodontal bacteria, or may be an innate feature of periodontitis patients.

Salivary antioxidants and periodontal disease status

Periodontal disease is a common chronic adult condition. The bacterium Porphyromonas gingivalis has been implicated in the aetiology of this disease, which causes destruction of the connective tissue and bone around the root area of the tooth. It has been observed that invading P. gingivalis bacteria trigger the release of cytokines such as interleukin 8 and tumour necrosis factor a, leading to elevated numbers and activity of polymorphonucleocytes (PMN). As a result of stimulation by bacterial antigens, PMN produce the reactive oxygen species (ROS) superoxide via the respiratory burst as part of the host response to infection. Patients with periodontal disease display increased PMN number and activity. It has been suggested that this proliferation results in a high degree of ROS release, culminating in heightened oxidative damage to gingival tissue, periodontal ligament and alveolar bone. Antioxidant constituents in plasma have been well-documented, being chiefly ascorbate, albumin and urate, and these are known to display sensitivity to dietary antioxidant intakes. The concentration of antioxidants in saliva does not appear to mirror those of plasma. The extent of dietary influence upon salivary antioxidant status is unclear. Urate is the predominant salivary antioxidant, with albumin and ascorbate providing minor contributions. Previous research has found reduced salivary antioxidant activity in patients suffering from periodontal disease. An improved understanding of the role antioxidants play in periodontitis, and the influence of nutrition on antioxidant status, may lead to a possible nutritional strategy for the treatment of periodontal disease.

Reactive oxygen species: a potential role in the pathogenesis of periodontal diseases

The pathological events leading to the destruction of the periodontium during inflammatory periodontal diseases are likely to represent complex interactions involving an imbalance in enzymic and non-enzymic degradative mechanisms. This paper aims to review the increasing body of evidence implicating reactive oxygen species (ROS), derived from many metabolic sources, in the pathogenesis of periodontal tissue destruction. ROS are generated predominantly by polymorphonuclear leukocytes (PMN) during an inflammatory response and are regarded as being highly destructive in nature. The detection of ROS oxidation products, the elevation of iron and copper ions, which catalyse the production of the most reactive radical species, and the identification of an imbalance in the oxidant/antioxidant activity within periodontal pockets, suggests a significant role for ROS in periodontal tissue destruction. In vitro studies have shown that ROS are capable of degrading a number of extracellular matrix components including proteoglycans, resulting in the modification of amino acid functional groups, leading to fragmentation of the core protein, whilst the constituent glycosaminoglycan chains undergo limited depolymerisation. The identification and characterisation of connective tissue metabolites in gingival crevicular fluid (GCF) resulting from the degradation of periodontal tissues, notably alveolar bone, provides further evidence for a role for ROS in tissue destruction associated with inflammatory periodontal diseases.

Oxidative injury and inflammatory periodontal diseases: the challenge of anti-oxidants to free radicals and reactive oxygen species

In recent years, there has been a tremendous expansion in medical and dental research concerned with free radicals, reactive oxygen species, and anti-oxidant defense mechanisms. This review is intended to provide a critical, up-to-date summary of the field, with particular emphasis on its implications for the application of "anti-oxidant therapy" in periodontal disease. We have reviewed the nomenclature, mechanisms of actions, features, and sources of most common free radicals and reactive oxygen species, as well as analyzed the typical biological targets for oxidative damage. Based on a review of direct and indirect anti-oxidant host defenses, particularly in relation to the key role of polymorphonuclear neutrophils in periodontitis, we review current evidence for oxidative damage in chronic inflammatory periodontal disease, and the possible therapeutic effects of anti-oxidants in treating and/or preventing such pathology, with special attention to vitamin E and Co-enzyme Q.

Degradation of glycosaminoglycans by reactive oxygen species derived from stimulated polymorphonuclear leukocytes

The effect of reactive oxygen species (ROS), generated by in vitro stimulation of isolated PMN upon the main GAG components of mineralised and non-mineralised connective tissues was investigated. PMN were isolated from whole blood and the production of the ROS superoxide (O2.-) and hydroxyl radicals (.OH) was stimulated by the addition of phorbol myristyl acetate (PMA) and PMA/FeCl3-EDTA chelate respectively and their production assessed over a 24 h period. The glycosaminoglycans (GAG), hyaluronan, chondroitin 4-sulphate and dermatan sulphate, were exposed to the ROS fluxes, incubated at 37 degrees C for 1 h and 24 h. GAG fragmentation was examined by gel exclusion chromatography and modification to hexuronic acid and hexosamine residues determined. Stimulation of PMN with PMA resulted in a burst of O2.- production for 1 h, which was sustained at a reduced level for 24 h. Fragmentation of GAG was observed for all GAG examined. Modification to the GAG was evident, with hyaluronan being more susceptible to loss of GAG residues than sulphated GAG. Modification of sugar residues increased with the incubation time and loss of the hexuronic acid residues was greater than loss of hexosamine residues. Addition of FeCl3-EDTA chelate, which led to the generation of .OH and was sustained over the 24 h period, demonstrated similar trends of GAG modification although increased degradation and loss of hexosamine and hexuronic acid were observed. GAG chains are constituents of PGs and their modification is likely to affect the function of these macromolecules and be of importance in considering the pathogenesis of inflammatory diseases, including periodontal diseases.

Enhanced chemiluminescent assay for measuring the total antioxidant capacity of serum, saliva and crevicular fluid

This paper reports the development of an enhanced chemiluminescent (ECL) assay for measuring the total antioxidant (AO) capacity of serum, saliva and a fluid collectable from the gum margin called gingival crevicular fluid (GCF). The theory behind the assay is explained, and the optimum conditions for the assay, and for storage of reagents and clinical samples is described. Calibration lines were linear (R > or = 0.99; P < 0.0001) and the within batch coefficient of variations for a water soluble vitamin E analogue (Trolox), serum and saliva samples were < 5%. In saliva and GCF, a characteristic AO response not seen in serum of the same patients, was identified. Total peripheral (serum) and local (saliva) AO capacities (mumol/L Trolox) were investigated in patients with (n = 18) and without (n = 16) adult periodontitis. Serum AO status did not differ between groups. Salivary total AO concentrations were lower in the peridontitis (P) group [175 (53) mumol/L] than in the non-periodontitis (NP) group [254 (110) mumol/L1: P < 0.01], as were saliva:serum AO ratio's [0.37 (0.11) versus 0.5 (0.18): P < 0.01]. Periodontitis patients may have a reduced salivary AO concentration, which could result from, or predispose to, the damaging effects of reactive oxygen species (ROS). The potential for ROS production in the oral and periodontal environment may explain the presence of a specific antioxidant in oral fluids that is not detectable in serum. The ECL assay described provides a rapid, simple and reproducible method of measuring total antioxidant defence in small volumes of biological fluids.

Reactive oxygen species and antioxidants in inflammatory diseases

This paper aims to review the rôle of free radical-induced tissue damage and antioxidant defence mechanisms in inflammatory diseases that involve pathogenic processes similar to the periodontal diseases. There is a clearly defined and substantial role for free radicals or reactive oxygen species (ROS) in periodontitis, but little research has been performed in this area. This paper reviews the considerable data available relating ROS activity and antioxidant defence to inflammatory diseases and attempts to draw parallels with periodontitis, in an effort to stimulate more periodontal research in this important area. The recent discovery of the transcription factor nuclear factor kappa B (NF-kappa B) is reviewed and several potential pathways for cytokine-induced periodontal tissue damage, mediated by NF-kappa B1 are discussed. Emphasis is placed on cytokines that have been studied in periodontitis, principally TNF-alpha, IL-1, IL-6, IL-8 and beta-interferon. The link between cellular production of such important mediators of inflammation and the antioxidant (AO) thiols, cysteine and reduced glutathione (GSH), is discussed and it is hypothesised that NF-kappa B antagonists may offer important therapeutic benefits.

Stimulation of plasminogen activator/plasmin system in gingival fibroblast cells by oxygen radicals

The effect of extracellular oxygen radicals on cultured gingival fibroblast cells (Gin cells) was investigated in the plasminogen activator (PA)/plasmin system. The activation of the PA/plasmin system in Gin cells exposed to a sublethal oxygen radical [hypoxanthine (HX) 0.1 mg ml-1/xanthine oxidase (XOD) 5 munit ml-1] system was examined. Following a 1 h exposure, washed cells were cultured for up to 24 h in fresh medium containing 2% fetal calf serum. The exogenous addition of superoxide dismutase, an oxygen radical scavenger, abolished the PA/plasmin activity enhanced by the HX/XOD system. The PA produced by Gin cells was found to be urokinase-type PA (uPA), as preincubation of Gin cell-conditioned medium with anti-uPa serum completely inhibited PA activity. These findings suggest that extracellular oxidant targetting to Gin cells may be involved in the progression of inflammation and the invasion of periodontium through stimulation of the PA/plasmin system.

The chemical modification of glycosaminoglycan structure by oxygen-derived species in vitro

The effect of reactive oxygen species (ROS) on the chemical structure of glycosaminoglycans (GAG) was studied in order to consider their role in connective tissue damage during an inflammatory disease state such as periodontal disease. GAG were exposed to a radical generating system for 1 h and analysed by gel filtration for fragmentation and chemically with respect to uronic acid, hexosamine and sulfate content. Non-sulfated GAG, hyaluronan and chondroitin, were most susceptible to depolymerisation and chemical modification of uronic acid and hexosamine residues by ROS. Depolymerisation and chemical modification of sulfated GAG, chondroitin 4-sulfate, dermatan sulfate and heparan sulfate was significantly less than for non-sulfated GAG. The highly sulfated GAG heparin showed minimal depolymerisation by ROS, but uronic acid residues were readily modified. Analysis of the ROS-exposed residues suggests that uronic acid is capable of degrading to a 3-carbon aldehyde, malondialdehyde. Chondroitin sulfate exposed to ROS resulted in marginal desulfation. The results suggest that the presence of sulfate on the GAG chain may protect the molecule against ROS attack. However, chemical modification of GAG may affect proteoglycan function and be of importance in considering connective tissue destruction in a variety of pathological situations, including periodontal disease.

Prospects for the use of antioxidant therapies

Free radical oxidative stress has been implicated in the pathogenesis of a variety of human diseases. Natural antioxidant defences have been found to be defective in many of the same diseases. This has led to suggestions that oxidative damage and therefore disease progression may be retarded by supplementing natural antioxidant defences. Potential antioxidant therapy includes natural antioxidant enzymes and vitamins or synthetic agents with antioxidant activity. Diseases where antioxidant therapy may be beneficial include diabetes mellitus, reperfusion injury, inflammatory diseases and the prevention of chronic processes such as atherosclerosis and carcinogenesis. Further well controlled prospective clinical trials of antioxidants are required to establish the efficacy and tolerability of antioxidant therapy in the treatment of human diseases.