Oxidative damage of periodontal tissue in the rat periodontitis model: effects of a high-cholesterol diet

N-acetylcysteine as a novel methacrylate-based resin cement component: effect on cell apoptosis and genotoxicity in human gingival fibroblasts

BACKGROUND

N-acetylcysteine (NAC) reduces the cytotoxicity and genotoxicity induced by monomers leached from dental composite resins. Herein, we investigated the effects of methacrylate-based resin cement used in dental implant restoration on apoptosis and genotoxicity, as well as the antiapoptotic and antigenotoxic capabilities of its component, NAC.

METHODS

The antioxidant NAC (0.1 or 1 wt.%) was experimentally incorporated into the methacrylate-based dental resin cement Premier®. The Premier® + NAC (0.1 or 1 wt.%) mixture was subsequently immersed into Dulbecco's modified Eagle's medium for 72 h, and used to treat human gingival fibroblasts (HGFs). The viability of HGFs was determined using the XTT assay. The formation of deoxyribonucleic acid (DNA) double-strand breaks (DNA-DSBs) was determined using a γ-H2AX assay. Reactive oxygen species (ROS), apoptosis, necrosis, and cell cycles were detected and analyzed using flow cytometry.

RESULTS

The eluate of Premier® significantly inhibited HGF proliferation in vitro by promoting a G1-phase cell cycle arrest, resulting in cell apoptosis. Significant ROS production and DNA-DSB induction were also found in HGFs exposed to the eluate. Incorporating NAC (1 wt.%) into Premier® was found to reduce cell cytotoxicity, the percentage of G1-phase cells, cell apoptosis, ROS production, and DNA-DSB induction.

CONCLUSION

Incorporating NAC (1 wt.%) into methacrylate-based resin cement Premier® decreases the cell cytotoxicity, ROS production, and DNA-DSBs associated with resin use, and further offers protective effects against the early stages of cell apoptosis and G1-phase cell cycle arrest in HGFs. Overall, our in vitro results indicate that the addition of NAC into methacrylate-based resin cements may have clinically beneficial effects on the cytotoxicity and genotoxicity of these materials.

Unraveling the Link Between Periodontal Disease and High Cholesterol: A Cross-Sectional Study

OBJECTIVE

This cross-sectional study aimed to investigate the association between high cholesterol levels and the prevalence of periodontal disease among patients in the United States, utilizing data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2017 and 2020. We hypothesize that patients with high cholesterol levels will have a high prevalence of periodontal disease.

METHODS

The study utilized a cross-sectional design, analyzing data from NHANES 2017-March 2020 pre-pandemic survey, a nationally representative survey. The sub-sample consisted of 7,042 participants aged 30 years and older who underwent the NHANES survey questionnaire. Information on high cholesterol levels and periodontal disease was obtained through self-reported data. Statistical analyses, using SAS 9.4 (SAS Institute Inc., Cary, NC), were performed to assess the association between high cholesterol levels and periodontal disease prevalence while controlling the potential confounding variables. Descriptive statistics and multivariable logistic regression were used.  Results: The study included a total of 7,042 participants. The mean age (SD) of the participants was 60.2 (13.7); 54% were females and 46% were males. Out of the total, 23% (1636) of the samples had periodontal disease and 52% (3669) of the participants had high cholesterol levels. Findings indicated a significant association between high cholesterol and periodontal disease (odds ratio, OR = 1.21, 95% confidence interval, CI = 1.06-1.40). Socioeconomic factors such as poverty and education, and other factors such as age, gender, race, smoking, physical activity, BMI, diabetes, hypertension, sugar intake, cholesterol intake, saturated fatty acids intake, and oral hygiene were identified as potential confounders.

CONCLUSION

This large-scale cross-sectional study investigated the association between high cholesterol and periodontal disease while comprehensively controlling for potential confounding factors. After adjusting for the relevant confounders, we found a weak positive association between high cholesterol and periodontal disease. While these findings provide valuable insights into the interplay between systemic health and oral health, the cross-sectional nature of the study limits the establishment of causality.

The etiological consideration of oxidized low-density lipoprotein in periodontitis

BACKGROUND

Epidemiologically, correlations between periodontal disease activity and CVD/serum lipid-related condition have been reported. Known mediators of these links include triglycerides, oxidized LDL (oxLDL) and inflammatory cytokines such as TNF-α supplied by adipocytes as well as oxidative degeneration products of these lipids. In this review, we focused on oxidized LDL and considered the relationship between periodontal disease and systemic conditions.

HIGHLIGHT

The degree of oxidation in the periodontal pocket can be evaluated by analyzing the Gingival Cervicular Fluid (GCF), which can be easily collected with paperpoint. The oxLDL/LDL ratio in GCF has been shown to be 17 times as high as that in blood, and IL-8 and IL-1β were also abundantly found in GCF. Periodontal treatment significantly lowers oxLDL levels in not only GCF but also plasma. In addition, there has been growing body of evidence that periodontal infections by periodontopathic bacteria affect arteriosclerosis. On the other hands, neutrophil extracellular traps (NETs), a form of innate immune responses, reportedly play a role as a defense mechanism in the periodontal pockets. However, the regulatory mechanism of NETs in periodontal pocket is still unknown. Recently, NETs induced by oxidized cholesterol have been reported to be involved in inflammatory damage to vascular endothelial cells.

CONCLUSION

Further understanding of the newly discovered roles of oxLDL in the defense and destruction of periodontal tissues are anticipated.

Better oral hygiene is associated with a reduced risk of cataract: A nationwide cohort study

Objective

To investigate the association of oral health status and oral hygiene behaviors with cataract occurrence longitudinally.

Materials and methods

Based on the National Health Screening cohort database of Korea, participants who underwent oral health screening by dentists in 2003 were included. Cataract was defined as two or more claims of disease classification for the International Classification of Diseases-10 (E10.34, E11.34, E12.34, E13.34, E14.34, H25, and H26) with cataract specific treatment or surgery procedure claim codes. The occurrence of cataract was analyzed with Cox proportional hazard model according to the presence of periodontitis and oral health examination findings, including missing teeth, caries, tooth brushing, and dental scaling.

Results

Overall, 103,619 subjects were included. During a median follow-up of 12.2 years, cataract developed in 12,114 (11.7%) participants. Poor oral health status such as the presence of periodontitis (adjusted hazard ratio [HR] 1.08, 95% CI [confidence interval] 0.99-1.17, p = 0.088) and increased number of missing teeth (adjusted HR = 1.74, 95% CI = 1.55-1.96, p < 0.001) was associated with the increased cataract risk. Better oral hygiene behaviors such as increased frequency of tooth brushing (adjusted HR = 0.84, 95% CI = 0.79-0.88, p < 0.001) and performed dental scaling within 1 year (adjusted HR = 0.90, 95% CI = 0.86-0.94, p < 0.001) were negatively associated with cataract occurrence.

Conclusion

Periodontitis and increased number of missing teeth may increase the risk of cataract. However, maintaining good oral hygiene through tooth brushing and dental scaling may reduce the risk of future cataract occurrence. Further studies should be performed to confirm the association between chronic oral inflammation and cataract.

Antimicrobial and anti-inflammatory activity of Cystatin C on human gingival fibroblast incubated with Porphyromonas gingivalis

Background

Periodontal disease is considered one of the most prevalent chronic infectious diseases, often leading to the disruption of tooth-supporting tissues, including alveolar bone, causing tooth mobility and loss. Porphyromonas gingivalis is considered the major etiological agent of this disease, having a plethora of virulence factors, including, lipopolysaccharides (LPS), hemolysins, and proteinases. Antimicrobial peptides are one of the main components of the innate immune response that inhibit the growth of P. gingivalis. The aim of this study was to analyze the antimicrobial activity of cystatin C and to assess the effect on the inflammatory and anti-inflammatory cytokines, the production of reactive oxygen species, and in the release of nitric oxide by human gingival fibroblasts incubated with P. gingivalis in the presence and absence of cystatin C.

Methods

P. gingivalis ATCC 33277 was exposed to cystatin C for 24h and co-cultured with human gingival fibroblasts (HGFs) ATCC CRL-2014. The effect of cystatin on growth of P. gingivalis and HGFs was evaluated. Pro-inflammatory (TNFα, IL-1β) and anti-inflammatory (IL-10) cytokines were determined by ELISA in the supernatants of HGFs incubated with P. gingivalis exposed to cystatin C. Additionally, nitrites and reactive oxygen species (ROS) production were evaluated.

Results

Cystatin Cinhibited the growth of P. gingivalis without affecting HGFs. Incubation of HGFs with P. gingivalis led to a significant increase of TNF-α and IL-1β. In contrast, HGFs incubated with P. gingivalis exposed to cystatin C showed a decreased production of both cytokines, whereas IL-10 was enhanced. Incubation of HGFs with P. gingivalis led to an increase of nitric oxide (NO) and ROS production, which was reduced in the presence of the peptide.

Conclusions

Cystatin C inhibits the growth of P. gingivalis and decreases the inflammatory cytokines, ROS, and NO production during infection of HGFs with P. gingivalis. Knowledge on the antimicrobial and immunomodulatory properties of cystatin C could aid in the design of new therapeutic approaches to facilitate the elimination of this bacterium to improve the treatment of periodontal disease.

Effect of peri-conception high fat diets on maternal ovarian function, fetal and placentome growth, and vascular umbilical development in goats

The objective of this study was to determine whether a high-fat diet (HFD) fed to goats for a brief period during peri-conception would optimize reproductive and fetal responses. Thirty-four Anglo-Nubian crossbred adult goats were allocated into three groups: control (n = 11), fed with a total mixed ration (TMR) based on chopped elephant grass and concentrate; HFBM (n = 11), given TMR supplemented with soybean oil on a 0.5% dry matter basis for 11 days starting nine days before mating (BM); and HFAM (n = 12), fed with soybean oil included in the TMR for 15 days after mating (AM). The TMR diets differed in their fat content (7.5% vs. 2.9%). All goats had estrus synchronized for 14 days BM by intravaginal administration of 60 mg MPA sponge for 12 days. Forty-eight hours BM, the sponge was removed and 0.075 mg PGF2α was applied intramuscularly. After 36 hours, 1 mL GnRH was administered intramuscularly, and goats were mated after sponge removal. The fat groups showed lower feed intake (P < 0.001) and higher cholesterol levels (P < 0.001) when HFD was administered. Doppler and B-mode ultrasound evaluations revealed a greater (P < 0.05) number of small (< 3 mm, 10 ± 0.6 vs 8 ± 0.5) and large (≥ 3 mm, 6 ± 0.4 vs 5.0 ± 0.2) follicles and intraovarian blood area (P < 0.05) in the HFBM group during sponge removal (57.6%) and mating (24.2%) than those of the no-fat group. During AM, the fat-fed groups exhibited higher glutathione peroxidase levels (P < 0.05) and a reduction (P < 0.001) in corpus luteum size (19%) and vascularized Doppler area (41%). No difference (P > 0.05) between groups was found in fetal traits, placentome, and umbilical vascular development, except for the embryonic vesicle where HFAM twin pregnancy showed a smaller size than the control (26.1 ± 3.5 cm vs 33.7 ± 2.7 cm; P < 0.01). Thus, HFD applied during peri-conception of goats has no impact on later fetal development but improved the follicular growth when given before the mating. Thus the use of HFD in periconception has no impact on fetal development but increases follicular growth before breeding time.

Macronutrient-induced modulation of periodontitis in rodents-a systematic review

CONTEXT

Consumption of dietary macronutrients is associated with the progression of a wide range of inflammatory diseases, either by direct modulation of host immune response or via microbiome. This includes periodontitis, a disease affecting tooth-supporting tissues.

OBJECTIVE

The aim of this work was to systematically review studies focusing on the effect of macronutrient (ie, carbohydrate, protein, fat) intake on periodontitis in rodents.

DATA SOURCES

Electronic searches were performed in February 2021 using the PubMed and Web of Science databases. Out of 883 articles reviewed, 23 studies were selected for additional analysis.

DATA EXTRACTION

Investigators extracted relevant data, including author names; the year of publication; article title; macronutrient composition; number and species of animals and their age at the start of the experiment; intervention period; method of periodontitis induction; and primary and secondary periodontitis outcomes. Quality assessment was done using the risk-of-bias tool for animal studies. After completing the data extraction, descriptive statistical information was obtained.

DATA ANALYSIS

High intakes of dietary cholesterol, saturated fatty acids, and processed carbohydrates such as sucrose, and protein-deficient diets were positively associated with periodontitis in rodents. This included greater amounts of alveolar bone loss, more lesions on periodontal tissues, and dental plaque accumulation. In contrast, high doses of milk basic protein in diets and diets with a high ratio of ω-3 to ω-6 fatty acids were negatively associated with periodontitis in rodents.

CONCLUSION

This work highlights the fact that, despite the large body of evidence linking macronutrients with inflammation and ageing, overall there is little information on how dietary nutrients affect periodontitis in animal models. In addition, there is inconsistency in data due to differences in methodology, outcome measurement, and dietary formulation. More studies are needed to examine the effects of different dietary macronutrients on periodontitis and investigate the underlying biological mechanisms.

Periodontitis Exacerbates and Promotes the Progression of Chronic Kidney Disease Through Oral Flora, Cytokines, and Oxidative Stress

Periodontitis is a type of systemic immune inflammation that is caused by the complex infection of a variety of microorganisms in the subgingival plaque and the imbalance of the microbial ecological environment in the mouth. Periodontitis and chronic kidney disease (CKD) share many risk factors, such as obesity, smoking, and age. A growing body of data supports a strong correlation between periodontitis and kidney disease. Evidence supports the role of periodontal inflammation and elevated serum inflammatory mediators in renal atherosclerosis, renal deterioration, and end-stage renal disease (ESRD) development. Periodontitis is a risk factor for kidney disease. However, to our knowledge, there are few studies detailing the possible link between periodontitis and CKD. This review summarizes the possible mechanisms underlying periodontitis and CKD. More importantly, it highlights novel and potential pathogenic factors for CKD, including bacteria, pro-inflammatory mediators and oxidative stress. However, most research on the relationship between periodontitis and systemic disease has not determined causality, and these diseases are largely linked by bidirectional associations. Future research will focus on exploring these links to contribute to new treatments for CKD.

Renin angiotensin system blockage by losartan neutralize hypercholesterolemia-induced inflammatory and oxidative injuries

Objectives: This study explores the protective role of losartan (LT) against oxidative and inflammatory damages in different physiological systems including heart, liver, and kidney tissue in hypercholesterolemic rats.

Methods: After induction of hypercholesterolemia by high cholesterol diet for 6 weeks, LT was administered for 4 weeks. In serum, the levels of lipoproteins, aminotransferases, creatine kinases, urea, apoptosis, and inflammatory markers were measured. In cardiac, hepatic, and renal tissues, lipid peroxidation product and GSH as well as antioxidant enzymatic activities were assayed. Finally, histopathological assessment evaluated the structural damage in cardiac, hepatic, and renal tissues.

Results: Serum markers of cardiac, hepatic, and renal toxicities including creatine kinases, aminotransferases, and urea were attenuated by LT in hypercholesterolemic animals. Moreover, LT markedly corrected the elevated levels of lipoproteins, apoptosis, and inflammatory biomarkers. Hypercholesterolemia-induced lipid peroxidation, low GSH levels, and diminished activities of antioxidant enzymes were prominently improved in LT treated animals. Histopathological alterations by hypercholesterolemia in heart, liver, and kidney tissues were ameliorated by LT.

Conclusion: This study confirmed the pathological enrollment of renin–angiotensin system in hypercholesterolemia-associated metabolic alterations. LT had a significant cardiac, hepatic, and renal protective role against these impairments through down-regulation of oxidative damage, inflammation and necrosis.

Alveolar Bone Loss, Tooth Loss and Oral Cancer Mortality in Older Patients: A Retrospective Cohort Study

PURPOSE

There has been growing interest in the association between periodontitis and systemic disease. In recent years, however, inconsistent results have also been found by case-control studies for the role of periodontitis in the development of oral cancer. This study aimed to examine whether periodontitis was an independent risk factor for oral cancer with a ≥75-year age group cohort.

MATERIALS AND METHODS

Between January 2010 and December 2014, 1385 patients aged ≥75 years who underwent radiographic examination were included in this retrospective cohort study. We collected demographic information and comorbid health conditions from local health authorities. Participants were followed up until either the occurrence of mortality, or the end of the study on December 31, 2018. Cox proportional hazards regression and competing risk hazard models were used to examine the association between periodontitis and oral cancer mortality.

RESULTS

Periodontitis and loss of teeth were significantly associated with oral cancer mortality. Compared to oral cancer mortality in healthy subjects, the HR and 95% CI in patients with mild, moderate, and severe periodontitis were 4.46 (0.94-21.06), 5.16 (1.14-23.39), and 6.65 (1.51-29.36), respectively. The HR (95% CI) was 1.05 (1.01-1.09) for tooth loss after controlling for potential confounding factors. All the increases in risk persisted in patients aged ≥80 years.

CONCLUSION

The present study provides substantial evidence that poor periodontal health is associated with oral cancer mortality. It is necessary to underline the importance of considering periodontitis in the prevention of oral cancer, particularly in the older patients.

Effects of Coffee Intake on Oxidative Stress During Aging-related Alterations in Periodontal Tissue

BACKGROUND/AIM

The purpose of this study was to determine the anti-aging effects of coffee intake on oxidative stress in rat periodontal tissue and alveolar bone loss.

MATERIALS AND METHODS

Male Fischer 344 rats (8 weeks old) were randomized to four groups; the baseline group immediately sacrificed, the control group fed with normal powdered food for 8 weeks, and the experimental groups fed with powdered food containing 0.62% or 1.36% coffee components for 8 weeks.

RESULTS

Alveolar bone loss and gingival level of 8-hydroxydeoxyguanosine were significantly lower in the 1.36% coffee group than in the control group. Nuclear factor erythroid 2-related factor 2 translocation to the nucleus was significantly higher in the 1.36% coffee group than in the control group.

CONCLUSION

Continuous intake of 1.36% coffee could prevent age-related oxidative stress in the periodontal tissue and alveolar bone loss, possibly by up-regulating the Nrf2 signaling pathway.

Expression of Salivary and Serum Malondialdehyde and Lipid Profile of Patients with Periodontitis and Coronary Heart Disease

Malondialdehyde (MAA) within a lipid pathway has been demonstrated to possess an important role in endothelial function that undergoes periodontitis and coronary heart disease (CHD) development. This study evaluated the impact of periodontitis, CHD, or a combination of both diseases (periodontitis + CHD) on salivary and serum MAA levels. The periodontal and clinical characteristics, serum, and saliva samples were collected from 32 healthy subjects, 34 patients with periodontitis, 33 patients with CHD, and 34 patients with periodontitis and CHD. Lipid profile and levels of MDA and C-reactive protein (CRP) were assessed. Patients in the periodontitis group (serum: 3.92 (3.7-4.4) µmol/L; salivary 1.81 (1-2.1) µmol/g protein, p < 0.01) and in the periodontitis + CHD (serum: 4.34 (3.7-4.8) µmol/L; salivary 1.96 (1.7-2.3) µmol/g protein, p < 0.001) group presented higher median concentrations of salivary and serum MAA compared to patients in the CHD (serum: 3.72 (3.5-4.1) µmol/L; salivary 1.59 (0.9-1.8) µmol/g protein, p < 0.01) and control group (serum: 3.14 (2.8-3.7) µmol/L; salivary 1.41 (0.8-1.6) µmol/g protein, p < 0.01). In univariate models, periodontitis (p = 0.034), CHD (p < 0.001), and CRP (p < 0.001) were significantly associated with MAA. In the multivariate model, only CRP remained a significant predictor of serum and salivary MAA (p < 0.001) MAA levels. Patients with periodontitis and with periodontitis + CHD presented higher levels of salivary and serum MAA compared to healthy subjects and CHD patients. CRP has been found to be a significant predictor of increased salivary and serum MAA levels.

Anti-hypercholesterolemic impacts of barley and date palm fruits on the ovary of Wistar albino rats and their offspring

A high cholesterol diet is related to ovarian dysfunction and infertility which has been increased among young ages consuming processed food products. The present study was conducted to evaluate the role of a high cholesterol diet on the ovaries of young female rats via assessments of histopathology, immunohistochemistry, oxidative stress and apoptic markers. Also, mating of hypercholesterolemic female rats was carried out to measure the fertility and numbers of their offspring. At the same time, phytotherapy was carried out through supplementing the diet with barley and/ or date palm fruits (10%) during the experiment to assess the phyto-therapeutic impacts in attenuation of drastic hypercholesterolemic effects. Hypercholesterolemic diet-fed rats exhibited damage of the ovarian follicles and increased follicular atresia. Furthermore, expression of cleaved caspase-3 was upregulated, while PCNA was downregulated in granulosa, theca and stroma cells. Hypercholesterolemic female rats showed marked depletion of antioxidative enzymes, increased lipid peroxidation and apoptotic markers. Alterations to the female serum hormones were detected. Offspring maternally fed on hypercholesterolemic diet showed a significant decrease of body weight and altered sex ratio. However, concomitant supplementation of barley and or date fruits to hypercholesterolemic groups revealed marked improvement of ovarian structure and function. On the basis of these evidences, it is believed that the enhanced synergistic effects of barley and/or date palm fruits in the amelioration of ovarian structure and functions were elicited by the potential antioxidant activity of their phytomicronutrients, polyphenols, β-glucan and trace elements. These materials scavenge free radicals from inflamed cells that can be used to establish an effective and novel therapeutic strategy for activating ovarian cell regeneration.

The effect of menopause on the relationship between hyperlipidemia and periodontal disease via salivary 8-hydroxy-2'-deoxyguanosine and myeloperoxidase levels

OBJECTIVE

Impairment of the lipid metabolism could affect the periodontal disease; increased oxidative stress may have a role in this relationship. The aim of the present study was to evaluate the role of menopause in the relationship between hyperlipidemia and periodontal disease via oxidative stress markers in saliva.

MATERIALS AND METHODS

Sixty-seven women were enrolled in the study and divided into four groups as systemically healthy and premenopause (C) (n = 18), hyperlipidemia and premenopause (H) (n = 16), systemically healthy and postmenopause (M) (n = 17), and hyperlipidemia and postmenopause (MH) (n = 16). Sociodemographics, periodontal and metabolic parameters, and saliva oxidative markers (myeloperoxidase [MPO] and 8-hydroxy-2'-deoxyguanosine [8-OHdG]) were evaluated.

RESULTS

Menopause and/or hyperlipidemia were associated with an increase in all evaluated periodontal parameters. Saliva 8-OHdG and MPO levels were higher in menopausal groups (M and MH). Multivariate linear regression analyses revealed that hyperlipidemia was related to an increase in periodontal parameters. Salivary oxidative stress markers and periodontal parameters were also positively associated with menopause and hyperlipidemia.

CONCLUSION

Saliva 8-OHdG and MPO levels may indicate that the relationship between periodontal disease and hyperlipidemia is aggravated by menopause.

Effects of Huanglian Jiedu Decoration in Rat Gingivitis

Gingivitis is an inflammatory disease that affects gingival tissues through a microbe-immune interaction. Huanglian Jiedu decoction (HLJD) is used traditionally for clearing and detoxifying in China, which had been reported to possess many pharmacological effects. Rat gingival inflammation model was established by lipopolysaccharide (LPS) injection for 3 consecutive days, and HLJD was given by gavage before LPS injection. After 3 days rats were sacrificed and tissue samples were evaluated. Serum cytokine levels such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were measured by enzyme-linked immunoabsorbent assay (ELISA). Oxidative stress related molecules such as total antioxidant capacity (T-AOC), malondialdehyde (MDA), and reactive oxygen species (ROS) were determined. Expression of AMP-activated protein kinase (AMPK) and extracellular signal-regulated kinases 1/2 (ERK1/2) signaling pathway were inspected by western blotting. Histological changes of gingival tissues were tested with hematoxylin-eosin (HE) staining. HLJD significantly decreased serum levels of IL-6 and TNF-α, suppressed generation of MDA and ROS, and enhanced T-AOC creation. Moreover, HLJD inhibited expressions of AMPK and ERK1/2. The inflammation severity of gingival tissue by HE staining was severe in model group but relieved in HLJD group obviously. HLJD exhibited protective effects against gingival damage through suppressing inflammation reaction and elevating antioxidation power.

Oxidative Stress and Antioxidants in the Diagnosis and Therapy of Periodontitis

Oxidative stress has been implicated in the pathogenesis of numerous diseases. However, large interventional studies with antioxidants failed to show benefits in the prevention or treatment of cardiovascular diseases, cancer, or diabetes mellitus. Numerous clinical studies have confirmed the association of oxidative stress markers and periodontitis. Technical and biological variability is high for most of the analyzed markers and none of them seems to be optimal for routine clinical use. In a research setting, analysis of a palette of oxidative stress markers is needed to cover lipid peroxidation, protein oxidation, and the antioxidant status. The source of reactive oxygen species and their role in the pathogenesis of periodontitis remains unclear. Interventional experiments indicate that oxidative stress might be more than just a simple consequence of the inflammation. Small studies have confirmed that some antioxidants could have therapeutic value at least as an addition to the standard non-surgical treatment of periodontitis. A clear evidence for the efficiency of antioxidant treatment in large patient cohorts is lacking. Potentially, because lowering of oxidative stress markers might be a secondary effect of anti-inflammatory or antibacterial agents. As the field of research of oxidative stress in periodontitis gains attraction and the number of relevant published papers is increasing a systematic overview of the conducted observational and interventional studies is needed. This review summarizes the currently available literature linking oxidative stress and periodontitis and points toward the potential of adjuvant antioxidant treatment, especially in cases where standard treatment fails to improve the periodontal status.

Visualization of Oxidative Stress Induced by Experimental Periodontitis in Keap1-Dependent Oxidative Stress Detector-Luciferase Mice

The aim of this study was to investigate whether a Keap1-dependent oxidative stress detector-luciferase (OKD-LUC) mouse model would be useful for the visualization of oxidative stress induced by experimental periodontitis. A ligature was placed around the mandibular first molars for seven days to induce periodontitis. Luciferase activity was measured with an intraperitoneal injection of d-luciferin on days 0, 1, and 7. The luciferase activity in the periodontitis group was significantly greater than that in the control group at seven days. The expressions of heme oxygenase-1 (HO-1) and malondialdehyde in periodontal tissue were significantly higher in the periodontitis group than in the control group. Immunofluorescent analysis confirmed that the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) occurred more frequently in the periodontitis group than in the control group. This study found that under oxidative stress induced by experimental periodontitis, the Nrf2/antioxidant defense pathway was activated and could be visualized from the luciferase activity in the OKD-LUC model. Thus, the OKD-LUC mouse model may be useful for exploring the mechanism underlying the relationship between the Nrf2/antioxidant defense pathway and periodontitis by enabling the visualization of oxidative stress over time.

A novel long noncoding RNA Lnc-HC binds hnRNPA2B1 to regulate expressions of Cyp7a1 and Abca1 in hepatocytic cholesterol metabolism

Cholesterol metabolism disorder in hepatocytes predicts a higher risk of metabolic syndrome (MetS). Long noncoding RNAs (lncRNAs) have emerged as critical players in cellular cholesterol metabolism, but their functions are not systematically clarified. Here, we have identified a novel lncRNA named lnc-HC negatively regulating cholesterol metabolism within hepatocytes through physical interaction with hnRNPA2B1. By further binding to the target messenger RNA of Cyp7a1 or Abca1, the lnc-HC-hnRNPA2B1 complex decreases expressions of the two genes that are implicated in cellular cholesterol excretion. lnc-HC knockdown can strongly recover the cholesterol disorder in vivo. In the upstream pathway, lnc-HC is up-regulated by high cholesterol by the transcription activator, CCAAT/enhancer-binding protein beta.

CONCLUSION

These findings suggest a subtle feed-forward regulation of lnc-HC in cholesterol metabolism and define a novel line of evidence by which lncRNAs modulate the metabolic system at the post-transcriptional level. (Hepatology 2016;64:58-72).

Prediabetes Enhances Periodontal Inflammation Consistent With Activation of Toll-Like Receptor-Mediated Nuclear Factor-κB Pathway in Rats

BACKGROUND

Clinical studies have showed that prediabetes (preDM) is a predisposing factor for periodontitis. However, the pathogenic mechanism involved is unclear. Because it is known that the activation of Toll-like receptor (TLR)-mediated nuclear factor-kappa B (NF-κB) signaling pathway plays a crucial role in periodontitis, it is hypothesized that preDM enhances periodontal inflammation by activation of the TLR-mediated NF-κB pathway.

METHODS

In this study, a preDM rat model is established by feeding a high-fat diet (HFD). HFD-induced rats with preDM (n = 7) and normal chow-fed rats (n = 7) were studied. The animal model was characterized in terms of body weight and the glycemic and insulinemic profiles. The following parameters were assessed to evaluate possible early periodontal alterations and underlying mechanisms: 1) histology analysis of periodontal tissue; and 2) serum and mRNA levels and/or the tissue protein expression of TLRs, myeloid differentiation factor 88 (MyD88), tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6), NF-κB, cytokines, advanced glucose ends (AGEs), and free fatty acids (FFAs).

RESULTS

Rats with preDM presented higher expression of TLR2 and TLR4 in periodontal tissue in the HFD group compared with the control group. The TLR2 and TLR4 was mostly expressed in gingiva, and TLR4 was expressed in periodontal ligament in rats. Furthermore, the MyD88 and TRAF6 protein levels were significantly increased in gingiva in rats with preDM compared with normal rats. The activity of NF-κB signals was higher in rats with preDM than in normal rats. Regarding cytokines expression, the TNF-α protein levels and interleukin-1β mRNA levels were significantly increased in the HFD group compared with the control group. In the serum, AGEs levels were significantly increased in the rats with preDM. Mean FFAs concentrations were increased in rats with preDM compared with normal rats, but it did not reach statistical significance.

CONCLUSION

In rats with preDM, TLR2 and TLR4 gene and protein levels were higher in periodontal tissue, and the activation of NF-κB may, through TLRs/MyD88, cause more cytokine secretion, which is associated with the onset or development of periodontal disease.

Gingival fibroblasts resist apoptosis in response to oxidative stress in a model of periodontal diseases

Periodontal diseases are classified as inflammation affecting the supporting tissue of teeth, which eventually leads to tooth loss. Mild reversible gingivitis and severe irreversible periodontitis are the most common periodontal diseases. Periodontal pathogens initiate the diseases. The bacterial toxin, lipopolysaccharide (LPS), triggers the inflammatory response and leads to oxidative stress. However, the progress of oxidative stress in periodontal diseases is unknown. The purpose of this study is to examine oxidative stress and cell damage in gingivitis and periodontitis. Our results showed that LPS increases reactive oxygen species (ROS) accumulation in gingival fibroblast (GF). However, oxidative stress resulting from excessive ROS did not influence DNA damage and cell apoptosis within 24 h. The mechanism may be related to the increased expression of DNA repair genes, Ogg1, Neil1 and Rad50. Detection of apoptosis-related proteins also showed anti-apoptotic effects and pro-apoptotic effects were balanced. The earliest damage appeared in DNA when increased γH2AX, an early biomarker for DNA damage, was detected in the LPS group after 48 h. Later, when recurrent inflammation persisted, 8-OHdG, a biomarker for oxidative stress was much higher in periodontitis model compared to the control in vivo. Staining of 8-OHdG in human periodontitis specimens confirmed the results. Furthermore, TUNEL staining of apoptotic cells indicated that the periodontitis model induced more cell apoptosis in gingival tissue. This suggested GF could resist early and acute inflammation (gingivitis), which was regarded as reversible, but recurrent and chronic inflammation (periodontitis) led to permanent cell damage and death.

Periodontal Disease-Induced Atherosclerosis and Oxidative Stress

Periodontal disease is a highly prevalent disorder affecting up to 80% of the global population. Recent epidemiological studies have shown an association between periodontal disease and cardiovascular disease, as oxidative stress plays an important role in chronic inflammatory diseases such as periodontal disease and cardiovascular disease. In this review, we focus on the mechanisms by which periodontopathic bacteria cause chronic inflammation through the enhancement of oxidative stress and accelerate cardiovascular disease. Furthermore, we comment on the antioxidative activity of catechin in atherosclerosis accelerated by periodontitis.

Oxidative Stress and Dietary Fat Type in Relation to Periodontal Disease

Oxidative stress is one of the main factors studied to explain the pathophysiological mechanisms of inflammatory conditions, such as periodontitis. In this respect, nutrition may be of great importance. Actually, research on nutrients' effects on periodontal diseases has expanded to include those influencing the redox status, which correlates to the inflammatory process. Dietary fat or lipids are often blamed as the major source of excess energy. Consequently, when caloric intake exceeds energy expenditure, the resultant substrate-induced increase in citric acid cycle activity generates an excess of reactive oxygen species (ROS). In addition, dietary fatty acid intake influences in relative fatty acid composition of biological membranes determining its susceptibility to oxidative alterations. From this standpoint, here, we reviewed studies analyzing the dietary fat role in periodontal disease. Research data suggest that periodontal health could be achieved by main dietary strategies which include substitution of saturated fats with monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), particularly n-3 PUFA. Maybe in the future, we should analyze the diet and provide some advice to periodontitis patients to improve treatment outcomes.

Evaluation of lipid peroxidation and oxidative DNA damage in patients with periodontitis and hyperlipidemia

BACKGROUND

The purpose of this study is to determine the serum levels of malondialdehyde (MDA), as a lipid peroxidation marker, and 8-hydroxydeoxyguanosine (8-OHdG), as an oxidative DNA damage marker, in patients with chronic periodontitis (CP) and hyperlipidemia.

METHODS

A total of 74 individuals were divided into four age- and sex-matched groups: 18 patients with hyperlipidemia and CP (HLp), 18 periodontally healthy patients with hyperlipidemia (HLh), 19 systemically healthy individuals with CP (Cp), and 19 systemically and periodontally healthy controls (Ch). Clinical periodontal parameters were measured, and serum lipids, MDA, and 8-OHdG levels were assessed in blood samples.

RESULTS

8-OHdG, MDA, probing depth, clinical attachment level, and percentage of sites bleeding on probing (BOP) were significantly higher in the HLp group than the Cp group. In the hyperlipidemic group, BOP was significantly correlated with total cholesterol, the ratio of total cholesterol to high-density lipoprotein cholesterol, and 8-OHdG levels. A significant correlation between 8-OHdG and MDA was also observed in the hyperlipidemia group.

CONCLUSIONS

In this study, serum MDA and 8-OHdG were found to be highest in the HLp group. The increased levels of MDA and 8-OHdG in HLp patients may be a result of a harmful oxidative status in association with hyperlipidemia and periodontitis.

Effects of hydrogen-rich water on aging periodontal tissues in rats

Oxidative damage is involved in age-related inflammatory reactions. The anti-oxidative effects of hydrogen-rich water suppress oxidative damage, which may aid in inhibiting age-related inflammatory reactions. We investigated the effects of drinking hydrogen-rich water on aging periodontal tissues in healthy rats. Four-month-old male Fischer 344 rats (n = 12) were divided into two groups: the experimental group (hydrogen-rich water treatment) and the control group (distilled water treatment). The rats consumed hydrogen-rich water or distilled water until 16 months of age. The experimental group exhibited lower periodontal oxidative damage at 16 months of age than the control group. Although protein expression of interleukin-1β did not differ, gene expression of Nod-like receptor protein 3 inflammasomes was activated in periodontal tissues from the experimental group as compared with the control group. Drinking hydrogen-rich water is proposed to have anti-aging effects on periodontal oxidative damage, but not on inflammatory reactions in healthy rats.

Association between hypertension and periodontitis: possible mechanisms

This review is to examine the current literatures on the relationship between periodontitis and hypertension as well as to explore the possible biological pathways underlying the linkage between these health conditions. Hypertension is one of the major risk factors for cardiovascular diseases. Oxidative stress and endothelial dysfunction are among the critical components in the development of hypertension. Inflammation has received much attention recently and may contribute to a pivotal role in hypertension. Periodontitis, a chronic low-grade inflammation of gingival tissue, has been linked to endothelial dysfunction, with blood pressure elevation and increased mortality risk in hypertensive patients. Inflammatory biomarkers are increased in hypertensive patients with periodontitis. Over the years, various researches have been performed to evaluate the involvement of periodontitis in the initiation and progression of hypertension. Many cross-sectional studies documented an association between hypertension and periodontitis. However, more well-designed prospective population trials need to be carried out to ascertain the role of periodontitis in hypertension.

Hyperlipidemia impaired innate immune response to periodontal pathogen porphyromonas gingivalis in apolipoprotein E knockout mice

A finely-tuned innate immune response plays a pivotal role in protecting host against bacterial invasion during periodontal disease progression. Hyperlipidemia has been suggested to exacerbate periodontal health condition. However, the underlying mechanism has not been addressed. In the present study, we investigated the effect of hyperlipidemia on innate immune responses to periodontal pathogen Porphyromonas gingivalis infection. Apolipoprotein E-deficient and wild-type mice at the age of 20 weeks were used for the study. Peritoneal macrophages were isolated and subsequently used for the study of viable P. gingivalis infection. ApoE^−/− mice demonstrated inhibited iNOS production and impaired clearance of P. gingivalis in vitro and in vivo; furthermore, ApoE^−/− mice displayed disrupted cytokine production pattern in response to P. gingivalis, with a decreased production of tumor necrosis factor-α, interleukin-6 (IL-6), IL-1β and monocyte chemotactic protein-1. Microarray data demonstrated that Toll-like receptor (TLR) and NOD-like receptor (NLR) pathway were altered in ApoE^−/− mice macrophages; further analysis of pattern recognition receptors (PRRs) demonstrated that expression of triggering receptors on myeloid cells-1 (TREM-1), an amplifier of the TLR and NLR pathway, was decreased in ApoE^−/− mice macrophages, leading to decreased recruitment of NF-κB onto the promoters of the TNF-α and IL-6. Our data suggest that in ApoE^−/− mice hyperlipidemia disrupts the expression of PRRs, and cripples the host’s capability to generate sufficient innate immune response to P. gingivalis, which may facilitate immune evasion, subgingival colonization and establishment of P. gingivalis in the periodontal niche.

Protective effect of rutin on the antioxidant genes expression in hypercholestrolemic male Westar rat

Background

High-cholesterol diet (HCD) increases the oxidative stress in different tissues leading to many diseases. Rutin (RT) is a natural flavonoid (vitamin p), which possesses an antioxidant activity with protective potential. The present study aimed to examine the potential effects of rutin on hypercholesterolemia-induced hepatotoxicity in rat.

Methods

Male Wistar rats were divided into four groups: GI) control (Rat chow), GII) Rutin (0.2% in rat chow), GIII) HCD (1% cholesterol and 0.5% cholic acid in rat chow) and GIV) rutin (0.2%) + HCD.

Results

Rutin in combination with HCD induced a significant protective effect against the hepatotoxicity by reducing the plasma level of alanine transaminase (ALT), aspartate aminotransferase (AST), triglyceride (TG), total cholesterol (TC), and low-density lipoprotein (LDL). The HCD (GII) showed a decrease in glutathione peroxidase (GPx), glutathione reductase (GR) and increase in glutathione S transferase α (GSTα), sulfiredoxin-1(Srx1), glutamate-cysteine ligase (GCL) and paraoxonase-1(PON-1) genes expression levels.

Conclusion

Treatment with rutin reversed all the altered genes induced by HCD nearly to the control levels. The present study concluded that the HCD feedings altered the expression levels of some genes involved in the oxidative stress pathway resulting in DNA damage and hepatotoxicity. Rutin have a hepatoprotective effect through the mechanism of enhancing the antioxidant effect via amelioration of oxidative stress genes.

Anti-aging Effects of Co-enzyme Q10 on Periodontal Tissues

Oxidative stress is associated with age-related reactions. The anti-oxidative effects of a reduced form of co-enzyme Q10 (rCoQ10) suppress oxidative stress, which may contribute to the prevention of age-related inflammatory reactions. We examined the effects of topically applied rCoQ10 on periodontal inflammatory reactions in a rat aging model. Male Fischer 344 rats, 2 (n = 6) and 4 mos (n = 18) of age, were used. All of the two-month-old rats and 6 of the four-month-old rats were sacrificed and 12 remaining four-month-old rats received topically applied ointment with or without 1% rCoQ10 on the gingival surface until they reached 6 mos of age. The rats showed an age-dependent increase in circulating oxidative stress. RCoQ10 decreased oxidative DNA damage and tartrate-resistant acid-phosphatase-positive osteoclasts in the periodontal tissue at 6 mos of age as compared with the control. The same conditions lowered gene expression of caspase-1 and interleukin-1β in the periodontal tissue. Furthermore, Nod-like receptor protein 3 inflammasomes were less activated in periodontal tissues from rCoQ10-treated rats as compared with the control rats. Our results suggest that rCoQ10 suppresses age-related inflammatory reactions and osteoclast differentiation by inhibiting oxidative stress.

Effects of biliverdin administration on acute lung injury induced by hemorrhagic shock and resuscitation in rats

Hemorrhagic shock and resuscitation induces pulmonary inflammation that leads to acute lung injury. Biliverdin, a metabolite of heme catabolism, has been shown to have potent cytoprotective, anti-inflammatory, and anti-oxidant effects. This study aimed to examine the effects of intravenous biliverdin administration on lung injury induced by hemorrhagic shock and resuscitation in rats. Biliverdin or vehicle was administered to the rats 1 h before sham or hemorrhagic shock-inducing surgery. The sham-operated rats underwent all surgical procedures except bleeding. To induce hemorrhagic shock, rats were bled to achieve a mean arterial pressure of 30 mmHg that was maintained for 60 min, followed by resuscitation with shed blood. Histopathological changes in the lungs were evaluated by histopathological scoring analysis. Inflammatory gene expression was determined by Northern blot analysis, and oxidative DNA damage was assessed by measuring 8-hydroxy-2′ deoxyguanosine levels in the lungs. Hemorrhagic shock and resuscitation resulted in prominent histopathological damage, including congestion, edema, cellular infiltration, and hemorrhage. Biliverdin administration prior to hemorrhagic shock and resuscitation significantly ameliorated these lung injuries as judged by histopathological improvement. After hemorrhagic shock and resuscitation, inflammatory gene expression of tumor necrosis factor-α and inducible nitric oxide synthase were increased by 18- and 8-fold, respectively. Inflammatory gene expression significantly decreased when biliverdin was administered prior to hemorrhagic shock and resuscitation. Moreover, after hemorrhagic shock and resuscitation, lung 8-hydroxy-2' deoxyguanosine levels in mitochondrial DNA expressed in the pulmonary interstitium increased by 1.5-fold. Biliverdin administration prior to hemorrhagic shock and resuscitation decreased mitochondrial 8-hydroxy-2' deoxyguanosine levels to almost the same level as that in the control animals. We also confirmed that biliverdin administration after hemorrhagic shock and resuscitation had protective effects on lung injury. Our findings suggest that biliverdin has a protective role, at least in part, against hemorrhagic shock and resuscitation-induced lung injury through anti-inflammatory and anti-oxidant mechanisms.

8-hydroxy-deoxyguanosine levels in gingival crevicular fluid and saliva in patients with chronic periodontitis after initial periodontal treatment

BACKGROUND

This study evaluates the effects of initial periodontal treatment on the gingival crevicular fluid (GCF) and salivary levels of 8-hydroxy-deoxyguanosine (8-OHdG) as a marker of oxidative deoxyribonucleic acid (DNA) damage in patients with chronic periodontitis (CP).

METHODS

At baseline, clinical parameters were determined and GCF and saliva samples were obtained from 24 patients with CP and 24 individuals with clinically healthy periodontium. GCF, saliva samples, and clinical periodontal measurements were repeated at day 10, 1 month, and 3 months following initial periodontal therapy in patients with CP. 8-OHdG levels of GCF and saliva samples were investigated by using an enzyme-linked immunosorbent assay.

RESULTS

Statistically significant higher 8-OHdG levels of GCF and a significant decrease after initial periodontal therapy were determined in the CP group (P <0.001). A significant positive correlation was found between 8-OHdG levels of GCF and clinical periodontal measurements (P <0.001). However, salivary levels of 8-OHdG did not differ between groups or during initial periodontal therapy (P >0.05).

CONCLUSIONS

This study reveals that DNA injury and oxidative stress increase in tissue cells and especially in periodontal pockets in patients with CP, and the periodontal treatment results in a significant decrease of 8-OHdG levels in the GCF samples. To the best of our knowledge, this study evaluates for the first time, 8-OHdG levels in GCF, which is shown to be more useful as a biomarker than saliva. 8-OHdG was found to be important and may reveal the severity of periodontal disease and the effect of periodontal therapy.

Supplementation of broccoli or Bifidobacterium longum-fermented broccoli suppresses serum lipid peroxidation and osteoclast differentiation on alveolar bone surface in rats fed a high-cholesterol diet

High-cholesterol diet enhances osteoclastic activity on alveolar bone by increasing serum lipid peroxidation. We hypothesized that supplementation with dietary antioxidants, such as found in broccoli and its fermented products, might suppress increases in serum lipid peroxidation, contributing to the inhibition of osteoclastic activity after high-cholesterol diet intake. The purpose of the present study was to investigate the effects of broccoli and fermented broccoli consumption on serum lipid peroxidation and osteoclast differentiation in alveolar bone of rats fed a high-cholesterol diet. In this 12-week study, rats were divided into 4 groups (n = 6/group): a control group (fed regular diet) and 3 experimental groups (fed a high-cholesterol [1% wt/wt] diet, or a high-cholesterol diet supplemented with either broccoli powder [5% wt/wt] or Bifidobacterium longum-fermented broccoli powder [5% wt/wt]). Serum hexanoyl-lysine (HEL) levels were measured as a parameter of lipid peroxidation. The number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in alveolar bone was enumerated to evaluate osteoclast differentiation. When compared with regular diet, the high-cholesterol diet increased serum HEL levels and resulted in a higher number of TRAP-positive osteoclasts at 12 weeks. The high-cholesterol diet supplemented with broccoli or B. longum-fermented broccoli showed lower levels of serum HEL and fewer TRAP-positive osteoclasts than the high-cholesterol diet at 12 weeks. In conclusion, consumption of broccoli, or its fermented product, inhibited the effects of a high-cholesterol diet on osteoclast differentiation in rat alveolar bone by suppressing serum lipid peroxidation.

Hydrogen-rich water attenuates experimental periodontitis in a rat model

AIM

Reactive oxygen species (ROS) contribute to the development of periodontitis. As molecular hydrogen can act as a scavenger of ROS, we examined the effects of treatment with hydrogen-rich water on a rat model of periodontitis.

MATERIAL & METHODS

A ligature was placed around the maxillary molars for 4 weeks to induce periodontitis, and the animals were given drinking water with or without hydrogen-rich water.

RESULTS

The rats with periodontitis which were treated with pure water showed a time-dependent increase in serum ROS level. Compared with the rats without periodontitis, the periodontitis-induced rats which were given pure water also showed polymorphonuclear leucocyte infiltration and alveolar bone loss at 4 weeks. Hydrogen-rich water intake inhibited an increase in serum ROS level and lowered expression of 8-hydroxydeoxyguanosine and nitrotyrosine in the periodontal tissue at 4 weeks. Such conditions prevented polymorphonuclear leucocyte infiltration and osteoclast differentiation following periodontitis progression. Furthermore, inflammatory signalling pathways, such as mitogen-activated protein kinases, were less activated in periodontal lesions from hydrogen-rich water-treated rats as compared with pure water-treated rats.

CONCLUSION

Consuming hydrogen-rich water might be beneficial in suppressing periodontitis progression by decreasing gingival oxidative stress.

The association between periodontal disease, physical activity and healthy diet among adults in Jordan

BACKGROUND AND OBJECTIVE

Physical inactivity and an unhealthy diet have been implicated as risk factors for several chronic diseases that are known to be associated with periodontitis, such as cardiovascular diseases, obesity and diabetes. Studies investigating the relationship between periodontitis and physical activity and diet are limited. Therefore, this study was conducted to determine the relationship between physical activity, healthy eating habits and periodontal health status.

MATERIAL AND METHODS

A systematic random sample of 340 persons, 18-70 years of age, was selected from persons accompanying their relative patients who attended the outpatient clinics in the medical center of Jordan University of Science and Technology in north of Jordan. Data collected included socio-demographic and clinical characteristics, anthropometric measurements, physical activity level and dietary assessment.

RESULTS

Individuals who were highly physically active had a significantly lower average plaque index, average gingival index, average clinical attachment loss (CAL) and percentage of sites with CAL ≥ 3 mm compared to individuals with a low level of physical activity and individuals with a moderate level of physical activity. Those who had a poor diet had a significantly higher average number of missing teeth and an average CAL compared with those who had a good diet. In the multivariate analysis, a low level of physical activity and a poor diet (diets with a healthy eating index score of < 50 points) were significantly associated with increased odds of periodontitis.

CONCLUSIONS

A low physical activity level and a poor diet were significantly associated with increased odds of periodontal disease. Further studies are needed to understand this relationship in greater detail.

Oxidative stress, systemic inflammation, and severe periodontitis

Periodontal infections have been associated with a state of chronic inflammation. To ascertain whether severe periodontitis and its treatment are associated with oxidative stress, we recruited 145 cases (periodontitis) and 56 controls in a case-control study. A further pilot intervention study of 14 cases (periodontal therapy) was performed. Blood samples were taken at baseline (case-control) and 1, 3, 5, 7, and 30 days after treatment (intervention). Diacron-reactive oxygen metabolites (D-ROM), anti-oxidant potential, C-reactive protein (CRP), interleukin-6, and lipid profiles were determined with high-sensitivity assays in serum. Patients with severe periodontitis exhibited higher D-ROM levels (P < 0.001) and lower total anti-oxidant capacity (P < 0.001) compared with healthy control individuals. These findings were independent of age, gender, smoking habits, ethnicity, and standard lipids differences. D-ROM levels were positively correlated with CRP (R = 0.4, P < 0.001) and clinical periodontal parameters (R = 0.20, P < 0.05). Acute increases of D-ROM (P < 0.01) were observed following periodontal therapy. Analysis of these data suggests a positive association between severe periodontitis and oxidative stress.

Oxidized low-density lipoprotein increases interleukin-8 production in human gingival epithelial cell line Ca9-22

BACKGROUND AND OBJECTIVE

Recent epidemiological studies have shown a correlation between periodontitis and hyperlipidemia. We have found high levels of oxidized low-density lipoprotein (OxLDL) in the gingival crevicular fluid of dental patients. In the present study, we tried to examine the possible role of OxLDL in periodontal inflammation in vitro.

MATERIAL AND METHODS

Cells of the human gingival epithelial cell line Ca9-22 were cultured in media containing OxLDL, and the amounts of interleukin-8 (IL-8) and prostaglandin E(2) (PGE(2)) produced were measured using ELISAs.

RESULTS

Production of IL-8 by Ca9-22 cells was significantly increased when the cells were treated with OxLDL, but not with native LDL or acetylated LDL. Production of PGE(2) by Ca9-22 cells was enhanced by co-incubation with OxLDL and interleukin-1 beta (IL-1 beta). Scavenger receptor inhibitors, fucoidan and dextran sulfate, inhibited the OxLDL-induced IL-8 and PGE(2) production in the presence of IL-1 beta. The p(38) MAPK inhibitors SB203580 and SB202190 and the ERK inhibitor PD98059 inhibited the OxLDL-induced IL-8 production. Among oxidized lipids and chemically modified LDL, 7-ketocholesterol enhanced IL-8 production.

CONCLUSION

This is the first report to show that OxLDL enhances IL-8 production in epithelial cells.

Lipopolysaccharide-induced epithelial monoamine oxidase mediates alveolar bone loss in a rat chronic wound model

Reactive oxygen species (ROS) production is an antimicrobial response to pathogenic challenge that may, in the case of persistent infection, have deleterious effects on the tissue of origin. A rat periodontal disease model was used to study ROS-induced chronic epithelial inflammation and bone loss. Lipopolysaccharide (LPS) was applied for 8 weeks into the gingival sulcus, and histological analysis confirmed the onset of chronic disease. Junctional epithelium was collected from healthy and diseased animals using laser-capture microdissection, and expression microarray analysis was performed. Of 19,730 genes changed in disease, 42 were up-regulated >/=4-fold. Three of the top 10 LPS-induced genes, monoamine oxidase B (MAO/B) and flavin-containing monooxygenase 1 and 2, are implicated in ROS signaling. LPS-associated induction of the ROS mediator H(2)O(2), as well as MAO/B and tumor necrosis factor (TNF)-alpha levels were validated in the rat histological sections and a porcine junctional epithelial cell culture model. Topical MAO inhibitors significantly counteracted LPS-associated elevation of H(2)O(2) production and TNF-alpha expression in vivo and in vitro, inhibited disease-associated apical migration and proliferation of junctional epithelium and inhibited induced systemic H(2)O(2) levels and alveolar bone loss in vivo. These results suggest that LPS induces chronic wounds via elevated MAO/B-mediated increases in H(2)O(2) and TNF-alpha activity by epithelial cells and is further associated with more distant effects on systemic oxidative stress and alveolar bone loss.

Effects of improvement in periodontal inflammation by toothbrushing on serum lipopolysaccharide concentration and liver injury in rats

OBJECTIVE

Periodontitis increases the serum lipopolysaccharide level, contributing to liver injury. Toothbrushing improves periodontitis and may also affect serum lipopolysaccharide concentration and periodontitis-induced liver injury. The purpose of the present study was to examine whether the improvement in periodontal inflammation by toothbrushing clinically affects the serum lipopolysaccharide level and hepatic pathological changes in rat periodontitis.

MATERIAL AND METHODS

Thirty male Wistar rats were divided into 5 groups, 2 groups receiving topical application of pyrogen-free water to the gingival sulcus for 4 or 8 weeks. The next 2 groups received topical application of lipopolysaccharide and proteases for 4 or 8 weeks. The last group received topical application of lipopolysaccharide and proteases for 8 weeks, and the palatal gingiva was brushed with a powered toothbrush once a day for 4 weeks prior to the end of the experimental period.

RESULTS

Topical application of lipopolysaccharide and proteases induced not only periodontal inflammation but also an elevation in the serum lipopolysaccharide concentration, with increasing hepatic inflammation, steatosis and 8-hydroxydeoxyguanosine levels in a time-dependent manner. The rats that received gingival stimulation showed decreased polymorphonuclear leukocyte infiltration and collagen loss levels in the periodontal lesions. Furthermore, this group also showed a decrease in serum lipopolysaccharide concentration and hepatic inflammation, steatosis and 8-hydroxydeoxyguanosine levels, compared with the group receiving no treatment.

CONCLUSIONS

Toothbrushing promoted healing of periodontal lesions, decreased serum lipopolysaccharide concentration and suppressed liver injury in a rat periodontitis model.

Effects of topical application of lipopolysaccharide and proteases on hepatic injury induced by high-cholesterol diet in rats

BACKGROUND AND OBJECTIVE

Topical application of lipopolysaccharide and proteases to the gingival sulcus induced not only periodontal inflammation but also detectable liver changes in rats fed a normal diet. However, these changes in the liver were not sufficient to induce pathological consequences. The purpose of the present study was to investigate whether gingival inflammation-induced liver change would have more dramatic pathological consequences in rats fed a high-cholesterol diet compared with the effect of the high-cholesterol diet alone.

MATERIAL AND METHODS

Twenty-four male Wistar rats were divided into four groups. During an 8 week experimental period, two groups were fed a normal diet and the other two were fed a high-cholesterol diet containing 1% cholesterol (w/w) and 0.5% cholic acid (w/w). Four weeks prior to the end of the experimental period, one of each of the dietary groups received daily topical application of lipopolysaccharide and proteases to the gingival sulcus, while the other was treated with pyrogen-free water.

RESULTS

In the rats without application of lipopolysaccharide and proteases, the serum level of hexanoyl-lysine, scores of steatosis and inflammation, and concentration of 8-hydroxydeoxyguanosine in liver of rats fed a high-cholesterol diet were higher than in those fed a normal diet. In rats fed a high-cholesterol diet, the scores of steatosis and inflammation and the concentration of 8-hydroxydeoxyguanosine in the liver of rats with application of lipopolysaccharide and proteases were higher than in those without.

CONCLUSION

In a rat model, application of lipopolysaccharide and proteases to the gingival sulcus augmented the effect of a high-cholesterol diet on steatosis, inflammation and oxidative damage in the liver.

Oral administration of vitamin C prevents alveolar bone resorption induced by high dietary cholesterol in rats

BACKGROUND

A high-cholesterol diet stimulates alveolar bone resorption, which may be induced via tissue oxidative damage. Vitamin C reduces tissue oxidative damage by neutralizing free radicals and scavenging hydroxyl radicals, and its antioxidant effect may offer the clinical benefit of preventing alveolar bone resorption in cases of hyperlipidemia. We examined whether vitamin C could suppress alveolar bone resorption in rats fed a high-cholesterol diet.

METHODS

In this 12-week study, rats were divided into four groups: a control group (fed a regular diet) and three experimental groups (fed a high-cholesterol diet supplemented with 0, 1, or 2 g/l vitamin C). Vitamin C was provided by adding it to the drinking water. The bone mineral density of the alveolar bone was analyzed by microcomputerized tomography. As an index of tissue oxidative damage, the 8-hydroxydeoxyguanosine level in the periodontal tissue was determined using a competitive enzyme-linked immunosorbent assay.

RESULTS

Hyperlipidemia, induced by a high-cholesterol diet, decreased rat alveolar bone density and increased the number of tartrate-resistant acid phosphatase-positive osteoclasts. The expression of 8-hydroxydeoxyguanosine was upregulated in the periodontal tissues. Intake of vitamin C reduced the effect of a high-cholesterol diet on alveolar bone density and osteoclast differentiation and decreased periodontal 8-hydroxydeoxyguanosine expression.

CONCLUSION

In the rat model, vitamin C suppressed alveolar bone resorption, induced by high dietary cholesterol, by decreasing the oxidative damage of periodontal tissue.