Levels of interleukin 1 beta in tissue from sites of active periodontal disease

DHA suppresses Prevotella intermedia lipopolysaccharide-induced production of proinflammatory mediators in murine macrophages

Several reports have indicated that dietary intake of DHA is associated with lower prevalence of periodontitis. In the present study, we investigated the effect of DHA on the production of proinflammatory mediators in murine macrophage-like RAW264.7 cells stimulated with lipopolysaccharide (LPS) isolated from Prevotella intermedia, a pathogen implicated in inflammatory periodontal disease, and its mechanisms of action. LPS was isolated from lyophilised P. intermedia ATCC 25,611 cells using the standard hot-phenol-water protocol. Culture supernatants were collected and assayed for NO, IL-1β and IL-6. Real-time PCR analysis was carried out to detect the expression of inducible NO synthase (iNOS), IL-1β, IL-6 and haeme oxygenase-1 (HO-1) mRNA. Immunoblot analysis was carried out to quantify the expression of iNOS and HO-1 protein and concentrations of signalling proteins. DNA-binding activities of NF-κB subunits were determined using an ELISA-based assay kit. DHA significantly attenuated the production of NO, IL-1β and IL-6 at both gene transcription and translation levels in P. intermedia LPS-activated RAW264.7 cells. DHA induced the expression of HO-1 in cells treated with P. intermedia LPS. Selective inhibition of HO-1 activity by tin protoporphyrin IX significantly mitigated the inhibitory effects of DHA on LPS-induced NO production. DHA significantly attenuated the phosphorylation of c-Jun N-terminal kinase induced by LPS. In addition, DHA suppressed the transcriptional activity of NF-κB by regulating the nuclear translocation and DNA-binding activity of NF-κB p50 subunit and inhibited the phosphorylation of signal transducer and activator of transcription 1. Further in vivo studies are needed to better evaluate the potential of DHA in humans as a therapeutic agent to treat periodontal disease.

Environmental stimuli shape biofilm formation and the virulence of periodontal pathogens

Periodontitis is a common inflammatory disease affecting the tooth-supporting structures. It is initiated by bacteria growing as a biofilm at the gingival margin, and communication of the biofilms differs in health and disease. The bacterial composition of periodontitis-associated biofilms has been well documented and is under continual investigation. However, the roles of several host response and inflammation driven environmental stimuli on biofilm formation is not well understood. This review article addresses the effects of environmental factors such as pH, temperature, cytokines, hormones, and oxidative stress on periodontal biofilm formation and bacterial virulence.

Identification of a novel bacterial outer membrane interleukin-1Β-binding protein from Aggregatibacter actinomycetemcomitans

Aggregatibacteractinomycetemcomitans is a gram-negative opportunistic oral pathogen. It is frequently associated with subgingival biofilms of both chronic and aggressive periodontitis, and the diseased sites of the periodontium exhibit increased levels of the proinflammatory mediator interleukin (IL)-1β. Some bacterial species can alter their physiological properties as a result of sensing IL-1β. We have recently shown that this cytokine localizes to the cytoplasm of A. actinomycetemcomitans in co-cultures with organotypic gingival mucosa. However, current knowledge about the mechanism underlying bacterial IL-1β sensing is still limited. In this study, we characterized the interaction of A. actinomycetemcomitans total membrane protein with IL-1β through electrophoretic mobility shift assays. The interacting protein, which we have designated bacterial interleukin receptor I (BilRI), was identified through mass spectrometry and was found to be Pasteurellaceae specific. Based on the results obtained using protein function prediction tools, this protein localizes to the outer membrane and contains a typical lipoprotein signal sequence. All six tested biofilm cultures of clinical A. actinomycetemcomitans strains expressed the protein according to phage display-derived antibody detection. Moreover, proteinase K treatment of whole A. actinomycetemcomitans cells eliminated BilRI forms that were outer membrane specific, as determined through immunoblotting. The protein was overexpressed in Escherichia coli in both the outer membrane-associated form and a soluble cytoplasmic form. When assessed using flow cytometry, the BilRI-overexpressing E. coli cells were observed to bind 2.5 times more biotinylated-IL-1β than the control cells, as detected with avidin-FITC. Overexpression of BilRI did not cause binding of a biotinylated negative control protein. In a microplate assay, soluble BilRI bound to IL-1β, but this binding was not specific, as a control protein for IL-1β also interacted with BilRI. Our findings suggest that A. actinomycetemcomitans expresses an IL-1β-binding surface-exposed lipoprotein that may be part of the bacterial IL-1β-sensing system.

IL-4 inhibition of IL-1 induced Matrix metalloproteinase-3 (MMP-3) expression in human fibroblasts involves decreased AP-1 activation via negative crosstalk involving of Jun N-terminal kinase (JNK)

Matrix metalloproteinase-3 (MMP-3) over-expression is associated with tissue destruction in the context of chronic inflammation. Previous studies showed that IL-4 inhibits induction of MMP-3 by IL-1β, and suggested that AP-1 might be involved. Here we show that IL-1 induced binding of transcription factor AP-1 to the MMP-3 promoter consists primarily of c-Jun, JunB, and c-Fos and that binding of c-Jun and c-Fos is inhibited by the combination of cytokines while binding of Jun B is not. Mutation of the AP-1 site in the MMP-3 promoter decreased the ability of IL-4 to inhibit its transcription in transfected MG-63 cells. Western blotting showed that both cytokines activate Jun N-terminal kinase (JNK), but with somewhat different kinetics, and that activation of JNK by both cytokines individually is inhibited by the combination. These results indicate that IL-4 inhibition of MMP-3 expression is associated with reduction of IL-1 induced binding of active forms of the AP-1 dimer, while less active JunB-containing dimers remain, and suggest that these changes are associated with decreased activation of JNK.

Association between interleukin-1β C (3953/4)T polymorphism and chronic periodontitis: evidence from a meta-analysis

The aim of this study was to perform a meta-analysis to evaluated the association between interleukin-1β (IL-1β) C(3953/4)T polymorphism and chronic periodontitis (CP). Systematic searches of electronic databases and hand searching of references were performed, including PubMed, Embase and Web of Science. The pooled odds ratios (ORs) with 95% confidence intervals (95%CIs) were calculated. Publication bias was tested by Begg's funnel plot and Egger's regression test. Sensitivity analysis was conducted by limiting the meta-analysis studies conforming to Hardy-Weinberg equilibrium (HWE) or high quality (score ≥ 7). Data analyses were carried out by Stata 11.0. There were significant associations between IL-1β C(3953/4)T polymorphism and CP (for T allele vs. C allele: OR = 1.30, 95%CI = 1.05-1.60, p = 0.02; for T/T vs. C/C: OR = 1.66, 95%CI = 1.12-2.45, p = 0.01; for C/T+T/T vs. C/C: OR = 1.28, 95%CI = 0.99-1.65; and for T/T vs. C/T+C/C: OR = 1.62, 95%CI = 1.15-2.29, p = 0.006). When stratified by ethnicity, statistically significantly elevated risk was found for Caucasians, but not for Asians. When stratified by study design, evidences of significant association was observed between IL-1β C(3953/4)T polymorphism and CP in both population-based studies and hospital-based studies. This meta-analysis indicates that there is strong evidence for association between IL-1β C(3953/4)T polymorphism and CP.

Cytokines expression in saliva and peri-implant crevicular fluid of patients with peri-implant disease

OBJECTIVE

This study aimed to measure the levels of GM-CSF, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IFN-γ and TNF-α in peri-implant crevicular fluid (PICF) and saliva from patients with peri-implant disease.

METHODS

Twenty two total edentulous patients were divided into two groups: Mucositis (MU) patients with bone loss around the implants until the first thread and pocket depth ≤3 mm, and Peri-implantitis (PI) patients with at least one implant with bone loss around two or more threads and pocket depth ≥4 mm. The clinical parameters evaluated were probing pocket depth, bleeding on probing, and percentage of plaque. PICF samples were collected from MU sites, and from shallow (SPI) and deep (DPI) sites in PI. Unstimulated whole and parotid duct saliva was collected from all patients. The cytokines were measured by a multiplexed immunoassay.

RESULTS

PI patients had a higher percentage of plaque compared with MU (P = 0.02). MU sites had lower pocket depth compared to SPI (P = 0.001) and to DPI (P ≤ 0.001). In PICF, the levels of IL-1β were significantly higher in SPI sites compared to MU (P = 0.03). In the saliva from parotid, IL-8 and IL-12 were significantly higher in patients with PI (P = 0.04).

CONCLUSION

Elevated levels of IL-1β in PICF seem to be a characteristic trait of patients with peri-implantitis. The parotid duct saliva showed a significant increase in expression of IL-8, which might be related to a systemic response.

Gene polymorphism and protein of human pro- and anti-inflammatory cytokines in Chinese healthy subjects and chronic periodontitis patients

BACKGROUND

Periodontal disease is thought to arise from the interaction of various factors, including the susceptibility of the host, the presence of pathogenic organisms, and the absence of beneficial species. The genetic factors may play a significant role in the risk of periodontal diseases. Cytokines initiate, mediate and control immune and inflammatory responses. The aim of this study is to compare genotypes and soluble protein of pro and anti-inflammatory cytokines (IL-1α, IL-1β, IL-6, IFN-γ, IL-10, TNF-α and IL-4) in subjects with or free of chronic periodontitis.

METHODS

A total of 1,290 Chinese subjects were recruited to this clinical trial: 850 periodontally healthy controls and 440 periodontal patients. All subjects were free of systemic diseases. Oral examinations were performed, and the following parameters were recorded for each subject: supragingival/subgingival calculus, gingival recession, bleeding on probing (BOP), probing depth (PD), clinical attachment loss (CAL), gingival recession and tooth mobility. The peripheral blood samples were collected for genetic and enzyme linked immunosorbent assay (ELISA) analysis. Restriction enzymes were used for digestion of amplified fragments of IL-1α, IL-1β, IL-6, IFN-γ, IL-10, TNF-α and IL-4.

RESULTS

The protein expressions of patient and control samples for IL-1α, IL-1β, IL-6, TNF-α, IFN-γ, IL-10, and IL-4 measured by ELISA confirmed a statistically significant difference (p < 0.001). The digestion of fragments of various genes showed that the pro-inflammatory cytokines IL-1α and TNF-α, and the anti-inflammatory cytokines IL-4 and IL-10 demonstrated a correlation with chronic inflammation in patients (X2: p < 0.001). The remaining genes investigated in patients and healthy subjects (IL-1β, IL-6, IFN-γ and IL-10) did not show any significant difference.

CONCLUSIONS

The cytokine gene polymorphisms may be used as a marker for periodontitis susceptibility, clinical behaviour and severity. This detection offers early diagnosis and induction of prophylaxis to other family members against disease progression.

Interleukin-1β is internalised by viable Aggregatibacter actinomycetemcomitans biofilm and locates to the outer edges of nucleoids

The opportunistic pathogen Aggregatibacter actinomycetemcomitans causes periodontitis, which is a biofilm infection that destroys tooth-supportive tissues. Interleukin (IL)-1β, a central proinflammatory cytokine of periodontitis, is an essential first line cytokine for local inflammation that modulates the cell proliferation and anti-pathogen response of human gingival keratinocytes. Previously, we demonstrated that A. actinomycetemcomitans biofilms bind IL-1β; however, whether this binding is an active process is not known. In this study, we showed for the first time with immuno-electron microscopy that viable bacterial biofilm cells internalised IL-1β when co-cultured with an organotypic mucosa. Decreased biofilm viability hindered the ability of biofilm to sequester IL-1β and caused IL-1β leakage into the culture medium. In some A. actinomycetemcomitans cells, intracellular IL-1β localized to the outer edges of the nucleoids. We identified the DNA-binding protein HU as an IL-1β interacting protein with mass spectroscopy and showed the interaction of recombinant HU and IL-1βin vitro using enzyme-linked immunosorbent assay (ELISA). Close contact with a viable A. actinomycetemcomitans biofilm decreased the proliferation and apoptosis of human gingival keratinocytes as demonstrated using Ki-67 and the terminal deoxynucleotidyl transferase dUTP nick-end labelling (TUNEL) staining, respectively. Our results suggest that viable A. actinomycetemcomitans biofilms may disturb the critical first steps of local inflammation in periodontitis by binding and internalising IL-1β. The interaction of IL-1β with conserved HU provides a potential mechanism for shaping bacterial gene expression.

Analysis of IL1 gene polymorphisms and transcript levels in periodontal and chronic kidney disease

Chronic kidney disease (CKD) and periodontitis (PD) are complex inflammatory disturbances, influenced by genetic factors. Interleukin (IL)-1 genes code for inflammatory mediators involved in the physiopathogenesis of both diseases. Functional polymorphisms in IL1 genes modulate cytokine levels and have been associated with susceptibility to immune-inflammatory conditions.

OBJECTIVES

The aim of this study was investigate the association of functional IL1 gene polymorphisms and transcript levels with susceptibility to CKD and PD.

DESIGN

The sample consisted of 246 individuals, mean age 44.8 years, divided into: group 1 (64 patients without CKD and without PD), group 2 (58 without CKD and with PD), group 3 (52 with CKD and without PD) and group 4 (72 with CKD and with PD). DNA was obtained from cells of oral mucosa and polymorphisms IL1AC-889T, IL1BC-511T, IL1BC+3954T and IL1RN (intron 2) were analyzed by PCR-RFLP. Transcript levels from gingival tissues were analyzed by real-time PCR.

RESULTS

IL1RN(*)1 allele was associated with almost 4-fold increased risk for CKD (OR 3.92 95% CI=1.6-9.4, p=0.002). IL1RN(*)2 allele was associated with 3-fold increased risk for PD in CKD patients (OR 3.08 95% CI=1.2-7.9, p=0.019). Allele T for polymorphism IL1B+3954 was associated with CKD in PD patients (OR 2.28 95% CI=1.1-4.7, p=0.019). Significantly increased levels of transcripts of IL1A, IL1B and IL1RN genes were found in PD patients.

CONCLUSIONS

It was observed an evidence for association of IL1B and IL1RN alleles with susceptibility to CKD and PD. Higher levels of IL1 gene transcripts were found in PD patients.

MAPK usage in periodontal disease progression

In periodontal disease, host recognition of bacterial constituents, including lipopolysaccharide (LPS), induces p38 MAPK activation and subsequent inflammatory cytokine expression, favoring osteoclastogenesis and increased net bone resorption in the local periodontal environment. In this paper, we discuss evidence that the p38/MAPK-activated protein kinase-2 (MK2) signaling axis is needed for periodontal disease progression: an orally administered p38α inhibitor reduced the progression of experimental periodontal bone loss by reducing inflammation and cytokine expression. Subsequently, the significance of p38 signaling was confirmed with RNA interference to attenuate MK2-reduced cytokine expression and LPS-induced alveolar bone loss. MAPK phosphatase-1 (MKP-1), a negative regulator of MAPK activation, was also critical for periodontal disease progression. In MPK-1-deficient mice, p38-sustained activation increased osteoclast formation and bone loss, whereas MKP-1 overexpression dampened p38 signaling and subsequent cytokine expression. Finally, overexpression of the p38/MK2 target RNA-binding tristetraprolin (TTP) decreased mRNA stability of key inflammatory cytokines at the posttranscriptional level, thereby protecting against periodontal inflammation. Collectively, these studies highlight the importance of p38 MAPK signaling in immune cytokine production and periodontal disease progression.

Effects of periodontal therapy on GCF cytokines in generalized aggressive periodontitis subjects

AIM

To examine changes in levels of gingival crevicular fluid (GCF) cytokines, after periodontal therapy of generalized aggressive periodontitis (GAgP).

MATERIALS AND METHODS

Twenty-five periodontally healthy and 24 GAgP subjects had periodontal clinical parameters measured and gingival crevicular fluid (GCF) samples collected from up to 14 sites/subject. GCF samples were analysed using multiplex bead immunoassay for: GM-CSF, IFN-γ, IL-10, IL-1β, IL-2, IL-6 and TNF-α. Aggressive periodontitis subjects were randomly assigned to either scaling and root planing (SRP) alone or SRP plus systemic amoxicillin (500 mg) and metronidazole (400 mg) 3 times a day for 14 days. Clinical parameters and GCF cytokines were re-measured 6 months after treatment. Differences over time were analysed using the Wilcoxon test and between groups using the Mann-Whitney test.

RESULTS

Significant reductions in GCF GM-CSF, IL-1β and the ratio IL-1β/IL-10 and increases in GCF IL-6 were detected after therapy. The mean change in GCF cytokines did not differ significantly between groups.

CONCLUSIONS

Periodontal therapy improved GCF cytokine profiles by lowering IL-1β and increasing IL-10 levels. The reduction in GCF GM-CSF after therapy implicates this cytokine in the pathogenesis of GAgP. There was no difference between therapies in changes of GCF cytokines.

Diabetes and periodontitis

The main aim of this review is to update the reader with practical knowledge concerning the relationship between diabetes mellitus and periodontal diseases. Exclusive data is available on the association between these two chronic diseases till date. Articles published on this relationship often provide the knowledge of definitions of diabetes mellitus and periodontal diseases, prevalence, extent, severity of periodontal disease, complications of diabetes along with the possible underlying mechanisms. The authors reviewed human epidemiological studies, cross-sectional observations and longitudinal cohort, case control that evaluated variables exclusively over the past 30 years and the predominant findings from the “certain” articles are summarized in this review. This review clarifies certain queries such as 1) Do periodontal diseases have an effect on the metabolic control of diabetes? 2) Does diabetes act as a risk factor of periodontitis? 3) What are the possible underlying mechanisms relating the connection between these two chronic diseases? 4) What is the effect of periodontal intervention on metabolic control of diabetes? After a thorough survey of literature, it was observed that diabetes acts as a risk factor in development of periodontitis as periodontitis is significantly aggravated in patients suffering from diabetes having long term hyperglycemia. Different mechanisms underlying the association between the accelerated periodontal disease and diabetes are emerging but still more work is required. Major efforts are required to elucidate the impact of periodontal diseases on diabetes. At the same time, patients are needed to be made aware of regular periodontal maintenance schedule and oral hygiene.

Effect of 1,064-nm Nd:YAG laser therapy on GCF IL-1β and MMP-8 levels in patients with chronic periodontitis

The aim of this study was to evaluate the long-term effects of a combined periodontal treatment of scaling and root planing (SRP) and Nd:YAG laser (NDL) in chronic periodontitis (CP) patients. This was accomplished by determining the periodontal indices and the interleukin-1beta (IL-1β) and matrix metalloproteinase-8 (MMP-8) levels of the gingival crevicular fluid (GCF). This study was performed according to a random split-mouth-design, controlled clinical trial for sulcular debridement on 40 teeth from 20 patients with generalized moderate chronic periodontitis. The periodontal healing outcomes were compared after periodontal treatment with either SRP + NDL at 1 W (test side) or SRP (control side). Plaque index (PI), gingival index (GI), probing pocket depth (PPD), and clinical attachment level (CAL) were recorded, and samples of gingival crevicular fluid (GCF) were taken at baseline and post-therapy (3 and 9 months after treatment). The GCF samples were analyzed for IL-1β and MMP-8. There was postoperative improvement of all clinical parameters in both groups, but test side GI, PPD, and CAL recovery was higher than that of the control side (p < 0.05). Although levels of IL-1β and MMP-8 in GCF after treatment were lower in the test side than the control side, there was not a statistically significant difference (p > 0.05). In the long term, we found that SRP + NDL treatment of periodontal pockets was more effective than SRP alone in reducing PPD, CAL, GI, and GCF values.

MAPKs, activator protein-1 and nuclear factor-κB mediate production of interleukin-1β-stimulated cytokines, prostaglandin E₂ and MMP-1 in human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Determination of the interleukin-1 (IL-1) signaling cascades that lead to the production of various inflammatory mediators and catabolic factors may clarify attractive targets for therapeutic intervention for periodontitis. We comprehensively assessed the involvement of MAPKs, activator protein-1 (AP-1) and nuclear factor-κB (NF-κB) in IL-1β-induced production of interleukin-6 (IL-6), interleukin-8 (IL-8), prostaglandin E(2) (PGE(2) ) and MMP-1 in human periodontal ligament cells.

MATERIAL AND METHODS

Human periodontal ligament cells were pretreated with an inhibitor for each of the MAPKs or NF-κB and subsequently treated with IL-1β. Following treatment, phosphorylation of three types of MAPK (ERK, p38 MAPK and c-Jun N-terminal kinase), IκB kinase (IKK) α/β/γ and IκB-α, as well as the DNA binding activity of AP-1 and NF-κB and the production of IL-6, IL-8, PGE(2) and MMP-1, were determined by western blotting, a gel mobility shift assay and ELISA, respectively.

RESULTS

The three MAPKs, simultaneously activated by IL-1β, mediated the subsequent DNA binding of AP-1 at various magnitudes, while IKKα/β/γ, IκB-α and NF-κB were also involved in the IL-1 signaling cascade. Furthermore, IL-1β stimulated the production of IL-6, IL-8, PGE(2) and MMP-1 via activation of the three MAPKs and NF-κB, because inhibitors of these significantly suppressed the IL-1β-stimulated production of these factors.

CONCLUSION

Our results strongly suggest that MAPK, AP-1 and NF-κB mediate the IL-1β-stimulated synthesis of IL-6, IL-8, PGE(2) and MMP-1 in human periodontal ligament cells. Therefore, inhibition of activation of MAPK, AP-1 and/or NF-κB may lead to therapeutic effects on progression of periodontitis.

Trimeric form of intracellular ATP synthase subunit β of Aggregatibacter actinomycetemcomitans binds human interleukin-1β

Bacterial biofilms resist host defenses and antibiotics partly because of their decreased metabolism. Some bacteria use proinflammatory cytokines, such as interleukin (IL)-1β, as cues to promote biofilm formation and to alter virulence. Although one potential bacterial IL-1β receptor has been identified, current knowledge of the bacterial IL-1β sensing mechanism is limited. In chronic biofilm infection, periodontitis, Aggregatibacter actinomycetemcomitans requires tight adherence (tad)-locus to form biofilms, and tissue destroying active lesions contain more IL-1β than inactive ones. The effect of IL-1β on the metabolic activity of A. actinomycetemcomitans biofilm was tested using alamarBlue™. The binding of IL-1β to A. actinomycetemcomitans cells was investigated using transmission electron microscopy and flow cytometry. To identify the proteins which interacted with IL-1β, different protein fractions from A. actinomycetemcomitans were run in native-PAGE and blotted using biotinylated IL-1β and avidin-HRP, and identified using mass spectroscopy. We show that although IL-1β slightly increases the biofilm formation of A. actinomycetemcomitans, it reduces the metabolic activity of the biofilm. A similar reduction was observed with all tad-locus mutants except the secretin mutant, although all tested mutant strains as well as wild type strains bound IL-1β. Our results suggest that IL-1β might be transported into the A. actinomycetemcomitans cells, and the trimeric form of intracellular ATP synthase subunit β interacted with IL-1β, possibly explaining the decreased metabolic activity. Because ATP synthase is highly conserved, it might universally enhance biofilm resistance to host defense by binding IL-1β during inflammation.

Correlation of levels of interleukin-1β in gingival crevicular fluid to the clinical parameters of chronic periodontitis

AIM

BACKGROUND AND OBJECTIVES

IL-1β is a potent stimulator of bone resorption and has been implicated in the pathogenesis of periodontal destruction. Therefore, this study was designed to compare the levels of IL-1β of chronic periodontitis patients with the healthy subjects. Another objective of this study was to correlate IL-1β levels with the clinical parameters of the periodontal disease progression.

METHODS

For this study, total 60 subjects were chosen (30- healthy and 30-chronic periodontitis). Simplified oral hygiene index (OHI-S), gingival index (GI), periodontal disease index (PDI), probing depth (PD), tooth mobility, bleeding on probing (BOP) were recorded for all the subject. Gingival crevicular fluid (GCF) was collected and subjected for ELISA for estimation of IL-1β.

RESULTS

At the periodontal diseased sites, the IL-1β levels increased at least 2-fold as compared with healthy subjects. This increase was highly significant (p = 0.0000). Within the test group, IL-1β levels correlated positively and significantly with PDI, PD, BOP and tooth mobility. The correlations of IL-1β with PD (p = 0.000) and IL-1β with BOP (p = 0.0004) were highly significant.

INTERPRETATION AND CONCLUSION

These data suggest that amount of GCF IL-1β is closely associated with periodontal status. This relationship may be valuable in monitoring periodontal disease activity.

CLINICAL SIGNIFICANCE

It could be stated from this study on IL- 1β that there seem to be a strong correlation between periodontal tissue destruction and IL-1β. Furthermore IL-1β level could also differentiate between active and inactive periodontal lesions.

Short-term effects of periodontal therapy as an adjunct to anti-lipemic treatment

OBJECTIVE

This study was conducted to assess the effect of improved periodontal health following periodontal treatment on metabolic lipid control of patients on anti-lipemic treatment.

MATERIALS AND METHODS

The study population consisted of 20 patients aged 34-62 years with diagnoses of hyperlipidemia and chronic periodontitis. All patients used statin to treat their elevated levels of low-density lipoprotein cholesterol. Blood samples were obtained for measurement of serum lipids, fasting plasma glucose, and high sensitive C-reactive protein. Periodontal parameters, including plaque index, gingival index, probing pocket depth, clinical attachment level, and percentage of bleeding on probing, were evaluated. All parameters were assessed in each subject at baseline, after 3 months as a control (at the time of periodontal treatment), and 3 months after the non-surgical periodontal treatment that included scaling and root planning.

RESULTS

All lipid parameters decreased after the periodontal treatment, but only the decreases in total cholesterol and low-density lipoprotein cholesterol levels reached statistical significance compared to baseline (P = 0.002 and P = 0.003, respectively).

CONCLUSION

Improved periodontal health may influence metabolic control of hyperlipidemia and could be considered as an adjunct to the standard measures of hyperlipidemic patient care.

Inflammation and genetic risk indicators for early periodontitis in adults

BACKGROUND

This report is a further analysis of a study designed to determine clinical and microbial risk indicators for progressing periodontitis.

METHODS

One hundred ninety subjects who were periodontally healthy or had early signs of periodontitis (age range: 20 to 40 years) were monitored clinically at 6-month intervals followed by supragingival cleaning. At each visit, gingival crevicular fluid (GCF) and blood were collected for determination of interleukin (IL)-1β content (in GCF) and IL-1 genotype (in blood). Interproximal sites with a >1.5-mm increase in clinical attachment over 18 months were considered disease active. Characteristics were compared between active and inactive subjects.

RESULTS

IL-1β levels in GCF increased with the severity of disease and correlated well with clinical signs of incipient disease. However, the IL-1 genotype did not show any significant associations with disease or the extent of disease.

CONCLUSION

Indicators of inflammation may be important clinical determinants of future periodontal disease progression, but the IL-1 genotype was not a risk indictor for early (slight) periodontitis as defined in this subject population.

Fluid exudates from inflamed bone-anchored hearing aids demonstrate elevated levels of cytokines and biomarkers of tissue and bone metabolism

OBJECTIVE

The purpose of the current study was to determine the presence of biomarkers of tissue and bone metabolism and 10 cytokines within the fluid exudate from around bone anchored hearing aids (BAHAs), with a view to understanding the mechanisms of peri-BAHA inflammation.

STUDY DESIGN

Fluid exudate from around BAHAs was collected from volunteers (n = 10) with inflammation and controls (n = 10) without inflammation around the BAHA.

SETTING

Studies of periodontitis and dental peri-implantitis have demonstrated that fluid exudate, arising from the hard tissue-soft tissue junction, is increased during disease; this fluid contains biomarkers of tissue metabolism, bone metabolism and inflammation.

PATIENTS

Volunteers were recruited from the Queen Elizabeth Hospital, Birmingham, UK and New Cross Hospital, Wolverhampton, UK.

INTERVENTIONS

This was an observational study and no interventions were carried out as part of the study.

MAIN OUTCOME MEASURE

Biomarkers of tissue metabolism (MMP9, TIMP1 and 2), bone metabolism (RANKL and OPG) and cytokines (GM-CSF, interferon (IFN)-*, IL-1A, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10 and TNF>) were measured in the fluid samples by Luminex multianalyte assay.

RESULTS

Volumes of fluid exudate were significantly higher (p < 0.05) at sites of inflammation than from un-inflamed tissues surrounding BAHAs. IL-1*, IL-6, IL-8, TNF*, MMP9, TIMP1 and 2 were found in both inflamed and un-inflamed samples and levels were significantly higher in samples from inflamed sites. RANKL, IFN*, IL-2, IL-4, and GM-CSF were detected only at inflamed sites whereas OPG, IL-5 and IL-10 were not detected in any samples.

CONCLUSION

These data demonstrate that peri-BAHA tissues showing clinical signs of inflammation are associated with increased fluid exudate, which contains elevated levels of key biomarkers of inflammation and a biomarker profile that is consistent with increased tissue and bone remodeling around BAHAs.

Association of gingival crevicular fluid biomarkers during periodontal maintenance with subsequent progressive periodontitis

BACKGROUND

The analysis of biomarkers in gingival crevicular fluid (GCF) may be helpful in forecasting patient vulnerability to future attachment loss. The purpose of this study is to correlate GCF biomarkers of inflammation and bone resorption with subsequent periodontal attachment and bone loss in a longitudinal trial of a matrix metalloproteinase (MMP) inhibitor.

METHODS

GCF was collected from two periodontal pockets (mean +/- SD: 5.1 +/- 1.0 mm) at baseline and annually in postmenopausal females with moderate to advanced periodontitis undergoing periodontal maintenance every 3 to 4 months during a 2-year double-masked, placebo-controlled, randomized clinical trial of subantimicrobial dose doxycycline (SDD; 20 mg two times a day). Subjects were randomized to SDD (n = 64) or a placebo (n = 64). GCF was analyzed for the inflammation markers interleukin (IL)-1beta (using enzyme-linked immunosorbent assay), total collagenase activity (using hydrolysis of a synthetic octapeptide), and MMP-8 (using a Western blot) and the bone-resorption marker carboxyterminal telopeptide cross-link fragment of type I collagen (ICTP) (using a radioimmunoassay). Generalized estimating equations were used to associate these biomarkers, categorized into tertiles, with subsequent clinical attachment (using an automated disk probe) or interproximal bone loss (using radiography). Odds ratio (OR) values compared highest to lowest tertile groups.

RESULTS

Increases in GCF IL-1beta and MMP-8 during the first year of periodontal maintenance were associated with increased odds of subsequent (year 2) periodontal attachment loss (OR = 1.67; P = 0.01 and OR = 1.50; P = 0.02, respectively) driven by the placebo group. Elevated baseline ICTP was also associated with increased odds of 1- and 2-year loss of alveolar bone density (OR = 1.98; P = 0.0001) in the placebo group, not the SDD group, and a loss of bone height (OR = 1.38; P = 0.06), again driven by the placebo group.

CONCLUSION

These data support the hypothesis that elevated GCF biomarkers of inflammation and bone resorption from a small number of moderate/deep sites have the potential to identify patients who are vulnerable to progressive periodontitis, and SDD may modify that risk.

Gene polymorphisms in chronic periodontitis

We aimed to conduct a review of the literature for gene polymorphisms associated with chronic periodontitis (CP) susceptibility. A comprehensive search of the literature in English was performed using the keywords: periodontitis, periodontal disease, combined with the words genes, mutation, or polymorphism. Candidate gene polymorphism studies with a case-control design and reported genotype frequencies in CP patients were searched and reviewed. There is growing evidence that polymorphisms in the IL1, IL6, IL10, vitamin D receptor, and CD14 genes may be associated with CP in certain populations. However, carriage rates of the rare (R)-allele of any polymorphism varied considerably among studies and most of the studies appeared under-powered and did not correct for other risk factors. Larger cohorts, well-defined phenotypes, control for other risk factors, and analysis of multiple genes and polymorphisms within the same pathway are needed to get a more comprehensive insight into the contribution of gene polymorphisms in CP.

Expression profile of human gingival fibroblasts induced by interleukin-1beta reveals central role of nuclear factor-kappa B in stabilizing human gingival fibroblasts during inflammation

BACKGROUND

Interleukin (IL)-1beta is a key cytokine in the pathogenesis of periodontitis, and it induces inflammatory mediators in periodontal diseases. We developed immortalized human gingival fibroblasts (HGFs), investigated the effects of IL-1beta on the gene expression using expression arrays containing approximately 40,000 genes, and tested the role of nuclear factor-kappa B (NF-kappaB) in maintaining an activated HGF population.

METHODS

Total RNA was isolated from IL-1beta-induced and mock-induced control cells. Gene expression analyses were performed using expression arrays and confirmed by quantitative real-time polymerase chain reaction. Western blot analysis to show inhibitor of kappa B-alpha (IkappaBalpha) phosphorylation and immunostaining of cells for NF-kappaB nuclear translocation were performed. Apoptosis was confirmed by assay of poly ADP-ribose polymerase (PARP) cleavage.

RESULTS

A total of 382 probe sets corresponding to 254 genes were differentially expressed in IL-1beta-induced cells (P <0.001). A total of 215 genes were upregulated, and 39 genes were downregulated. Most notable NF-kappaB pathway members (NFkappaB1, NFkappaB2, IkappaBalpha, IkappaBepsilon, IkappaBzeta, REL, RELB, and TA-NFKBH) were upregulated. IkappaBalpha was phosphorylated, and NF-kappaB accumulated in the nucleus. An IL-1beta-induced set of 27 genes was downregulated by an NF-kappaB inhibitor, leading to a decreased number of viable cells and suggesting an antiapoptotic role for NF-kappaB.

CONCLUSIONS

IL-1beta leads to a large number of significant expression changes consistent with a pathologic role in periodontitis, including enhancement of inflammatory cytokines, chemokines, transcription factors, matrix metalloproteinases, adhesion molecules, and especially NF-kappaB-dependent antiapoptotic genes. NF-kappaB activation blocks apoptosis, thereby stabilizing the HGF population in inflammation.

Physical activity, inflammatory biomarkers in gingival crevicular fluid and periodontitis

AIMS

To examine the associations of physical activity with interleukin 1-beta (IL-1beta), C-reactive protein (CRP) and periodontitis and to investigate whether any relationship between physical activity and inflammatory mediators differs between periodontitis cases and non-cases.

MATERIAL AND METHODS

In this population-based case control study of Australians aged 18+ years, dentists conducted oral epidemiologic examinations identifying cases with moderate or severe periodontitis and periodontally healthy controls. Gingival crevicular fluid samples collected during examinations were analysed for inflammatory biomarkers. Subject-completed questionnaires assessed leisure-time physical activity. Exposure odds ratios (ORs) were estimated in multivariable logistic regression models adjusting for periodontitis risk indicators.

RESULTS

Of 751 subjects (359 cases, 392 controls), those meeting a prescribed threshold for leisure-time physical activity had lower adjusted odds of elevated IL-1beta: OR=0.69, (95% CI=0.50-0.94) and detectable CRP: OR=0.70 (0.50-0.98) than less active adults. Physical activity was not associated with periodontitis: OR=1.14 (0.80-1.62). Periodontitis modified the association between levels of physical activity and detectable CRP. Increasing quartiles of physically activity were associated with decreasing probability of detectable CRP, but the effect was limited to periodontitis cases and was not apparent among non-cases.

CONCLUSION

Leisure-time physical activity may protect against an excessive inflammatory response in periodontitis.

A multiplex immunoassay demonstrates reductions in gingival crevicular fluid cytokines following initial periodontal therapy

BACKGROUND AND OBJECTIVE

Cytokines and chemokines play an important role in the pathogenesis of periodontal diseases. The objective of this study was to quantitatively assess the effect of initial periodontal therapy on gingival crevicular fluid levels of a comprehensive panel of cytokines and chemokines, including several less extensively studied mediators.

MATERIAL AND METHODS

Clinical examinations were performed and gingival crevicular fluid samples obtained from six subjects with generalized severe chronic periodontitis prior to initial periodontal therapy and at re-evaluation (6-8 weeks). Four diseased and two healthy sites were sampled in each subject. Twenty-two gingival crevicular fluid mediators were examined using a multiplex antibody capture and detection platform. Statistical analyses were performed by fitting mixed effects linear models to log-transformed gingival crevicular fluid values.

RESULTS

Gingival crevicular fluid interleukin (IL)-1alpha and IL-1beta were the only cytokines to differ in initially diseased vs. initially healthy sites. Following initial therapy, 13 of the 16 detectable cytokines and chemokines decreased significantly in diseased sites, including IL-1alpha, IL-1beta, IL-2, IL-3, IL-6, IL-7, IL-8, IL-12 (p40), CCL5/regulated on activation, normally T cell expressed and secreted (RANTES), eotaxin, macrophage chemotactic protein-1, macrophage inflammatory protein-1alpha and interferon-gamma. At healthy sites, only three of the 16 mediators were significantly altered following therapy.

CONCLUSION

This is the first study, to our knowledge, to evaluate such an extensive panel of gingival crevicular fluid mediators within the same sample prior to and following initial therapy. The results confirm that periodontal therapy effectively reduces pro-inflammatory cytokines and chemokines, including less well-described mediators that may be important in initiation and progression of periodontitis. The multiplex assay will prove useful for future gingival crevicular fluid studies.

Periodontal status in subjects with hyperlipidemia

BACKGROUND

Hyperlipidemia is a major risk factor for cardiovascular disease. Recent reports showed a possible association between periodontal disease and an increased risk for cardiovascular disease. The aim of this study was to evaluate whether hyperlipidemia has any influence on periodontal status.

METHODS

Fifty-one subjects with hyperlipidemia and 47 normolipidemic subjects participated in this study. Biochemical parameters, including plasma triglyceride, total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels, and periodontal parameters, including plaque index (PI), probing depth (PD), clinical attachment level (CAL), and percentage of sites with bleeding on probing (BOP [%]), were evaluated.

RESULTS

The mean values of PI, PD, CAL, and BOP (%) for the hyperlipidemic group were significantly higher than those for the control group. Plasma triglyceride, total cholesterol, and LDL-C levels were significantly and positively associated with PI, PD, BOP (%), and CAL. HDL-C was significantly, but negatively, associated with CAL. Plasma triglyceride level was significantly associated with PD and BOP (%) after further analyses.

CONCLUSIONS

The results of our study showed that patients with mild or moderate hyperlipidemia manifested higher values of periodontal parameters compared to normolipidemic individuals. Further studies are needed to determine the effect of hyperlipidemia on periodontal disease.

Levels of serum interleukin (IL)-6 and gingival crevicular fluid of IL-1beta and prostaglandin E(2) among non-smoking subjects with gingivitis and type 2 diabetes

BACKGROUND

The goal of this study was to assess whether non-smoking patients with type 2 diabetes present with increased levels of local and systemic proinflammatory mediators and, if so, whether such an increase is associated with enhanced clinical gingival inflammation compared to non-smoking patients without diabetes.

METHODS

We used a cross-sectional database consisting of 725 self-reported lifelong non-smokers aged 53 to 74 years. Gingival crevicular fluid (GCF) levels of interleukin (IL)-1beta and prostaglandin E(2) (PGE(2)) and serum levels of IL-6 were measured using enzyme-linked immunosorbent assay. No participant had probing depth >3 mm. Participants with bleeding on probing (BOP) in <10% of sites were classified as healthy, whereas those with BOP in >or=10% of sites were defined as having biofilm-gingival interface (BGI) gingivitis.

RESULTS

Approximately 53% (n = 385) and 11% (n = 80) of the sample had BGI gingivitis and type 2 diabetes, respectively. The mean age-adjusted level of GCF IL-1beta was significantly elevated in the diabetic group compared to the non-diabetic group (P = 0.048), but serum IL-6 (P = 0.14) and GCF PGE(2) were not (P = 0.98). The mean GCF IL-1beta and PGE(2) levels were significantly elevated in subjects with BGI gingivitis (136.2 +/- 112.9 ng/ml and 277.2 +/- 187.2 ng/ml, respectively) compared to subjects with gingival health (95.9 +/- 82.9 ng/ml and 205.7 +/- 149.6 ng/ml, respectively), regardless of diabetic status (P <0.001 for both). However, serum IL-6 was elevated in subjects with BGI gingivitis compared to subjects with gingival health only among subjects with diabetes (2.9 +/- 3.2 pg/ml versus 1.5 +/- 1.4 pg/ml; P = 0.008). With the exception of serum IL-6 in subjects without diabetes, an increase in the levels of proinflammatory mediators was associated with increased odds of having BGI gingivitis. The associations were stronger in the diabetic group.

CONCLUSIONS

Type 2 diabetes may increase the host inflammatory response to oral biofilm, which, in turn, may exacerbate preconditions associated with gingivitis in susceptible individuals. Furthermore, systemic inflammation, as demonstrated by the increased level of serum IL-6, is associated with BGI gingivitis among non-smoking patients with diabetes.

Bone resorption in incompletely impacted mandibular third molars and acute pericoronitis

Acute pericoronitis (AP) arises frequently in incompletely impacted mandibular third molars, but it remains unknown whether bone resorption in aging is associated with acute inflammation of the third molar. We conducted an experiment to compare the ratio of bone resorption to root length in the distal surface of the second molar (A), the proximal surface (B), and distal surface (C) in mesio-angular, incompletely impacted third molars in 27 young and 58 older adults with AP and 77 young and 79 older adults without a history of AP. Bone resorption in A, B, and C in older adults with AP demonstrated a significantly higher ratio when compared to those without AP, whereas there was no difference between those with and without AP in young adults except for B in women. However, there were no differences between bone resorption in B with AP in young and older women, and between bone resorption in C with AP in young and older adults. These indicate that AP and bone resorption are associated with incompletely impacted mandibular third molars in older adults.

Short-term clinical and immunologic effects of scaling and root planing with Er:YAG laser in chronic periodontitis

BACKGROUND

Recently, the erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser has been used for periodontal therapy. This study compared Er:YAG laser irradiation (100 mJ/pulse, 10 Hz, 12.9 J/cm(2)) with or without conventional scaling and root planing (SRP) to SRP only for the treatment of periodontal pockets affected with chronic periodontitis.

METHODS

Twenty-one subjects with pockets from 5 to 9 mm in non-adjacent sites were studied. In a split-mouth design, each site was randomly allocated to a treatment group: SRP and laser (SRPL), laser only (L), SRP only (SRP), or no treatment (C). The plaque index (PI), gingival index (GI), bleeding on probing (BOP), and interleukin (IL)-1beta levels in crevicular fluid were evaluated at baseline and at 12 and 30 days postoperatively, whereas probing depth (PD), gingival recession (GR), and clinical attachment level (CAL) were evaluated at baseline and 30 days after treatment. A statistical analysis was conducted (P <0.05).

RESULTS

Twelve days postoperatively, the PI decreased for SRPL and SRP groups (P <0.05); the GI increased for L, SRP, and C groups but decreased for the SRPL group (P <0.05); and BOP decreased for SRPL, L, and SRP groups (P <0.01). Thirty days postoperatively, BOP decreased for treated groups and was lower than the C group (P <0.05). PD decreased in treated groups (P <0.001), and differences were found between SRPL and C groups (P <0.05). CAL gain was significant only for the SRP group (P <0.01). GR increased for SRPL and L groups (P <0.05). No difference in IL-1beta was detected among groups and periods.

CONCLUSION

Er:YAG laser irradiation may be used as an adjunctive aid for the treatment of periodontal pockets, although a significant CAL gain was observed with SRP alone and not with laser treatment.

An interleukin-1beta (IL-1beta) single-nucleotide polymorphism at position 3954 and red complex periodontopathogens independently and additively modulate the levels of IL-1beta in diseased periodontal tissues

Inflammatory cytokines such as interleukin-1beta (IL-1beta) are involved in the pathogenesis of periodontal diseases. A high individual variation in the levels of IL-1beta mRNA has been verified, which is possibly determined by genetic polymorphisms and/or by the presence of periodontopathogens such as Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, and Aggregatibacter actinomycetemcomitans. In this study, we investigated the role of an IL-1beta promoter single-nucleotide polymorphism at position 3954 [IL-1beta(3954) SNP] and the presence of the periodontopathogens in the determination of the IL-1beta levels in the periodontal tissues of nonsmoking chronic periodontitis (CP) patients (n = 117) and control (C) subjects (n = 175) and the possible correlations with the clinical parameters of the disease. IL-1beta(3954) SNP was investigated by restriction fragment length polymorphism, while the IL-1beta levels and the presence of the periodontopathogens were determined by real-time PCR. Similar frequencies of IL-1beta(3954) SNP were found in the C and CP groups, in spite of a trend toward a higher incidence of T alleles in the CP group. The IL-1beta(3954) SNP CT and TT genotypes, as well as P. gingivalis, T. forsythia, and T. denticola, were associated with higher IL-1beta levels and with higher values of the clinical parameters of disease severity. Concomitant analyses demonstrate that IL-1beta(3954) and the red complex periodontopathogens were found to independently and additively modulate the levels of IL-1beta in periodontal tissues. Similarly, the concurrent presence of both factors was associated with increased scores of disease severity. IL-1beta(3954) genotypes and red complex periodontopathogens, individually and additively, modulate the levels of IL-1beta in the diseased tissues of nonsmoking CP patients and, consequently, are potentially involved in the determination of the disease outcome.

Effect of non-surgical periodontal therapy on clinical and immunological response and glycaemic control in type 2 diabetic patients with moderate periodontitis

OBJECTIVES

The purpose of this study was to compare the local efficacy of nonsurgical periodontal therapy between type 2 diabetic and non-diabetic patients and the effect of periodontal therapy on glycaemic control.

BACKGROUND

A complex two-way relationship exists between diabetes mellitus and periodontitis.

MATERIALS AND METHODS

After selection, 20 subjects (10 diabetic and 10 non-diabetic) underwent baseline examination, periodontal clinical study and biochemical analysis of gingival crevicular fluid (GCF). After the pre-treatment phase, subgingival scaling and root planing were performed. Subsequently, all subjects continued the maintenance programme and were re-examined at 3 and 6 months.

RESULTS

Diabetic and non-diabetic subjects responded well after therapy, showing a very similar progression during the follow-up period. Both groups showed clinically and immunologically significant improvements. Significant reductions were also found in the total volume of GCF and levels of interleukin-1beta and tumour necrosis factor-alpha. Diabetic subjects showed an improvement in their metabolic control. The change in glycosylated haemoglobin (HbA(1C)) was statistically significant at 3 and 6 months.

CONCLUSIONS

The clinical and immunological improvements obtained were accompanied by a significant reduction in HbA(1C) values in type 2 diabetic subjects. Larger studies are needed to confirm this finding and establish whether periodontal therapy has a significant effect on glycaemic control.

Mitogen-activated protein kinases mediate interleukin-1?-induced receptor activator of nuclear factor-?B ligand expression in human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Interleukin-1beta-stimulated receptor activator of nuclear factor-kappaB ligand (RANKL) expression in human periodontal ligament cells is partially mediated by endogenous prostaglandin E2, whereas mitogen-activated protein kinases (MAPKs) are implicated in regulating various interleukin-1-responsive genes. We investigated herein the involvement of MAPKs in interleukin-1beta-stimulated RANKL expression in human periodontal ligament cells.

MATERIAL AND METHODS

Human periodontal ligament cells were pretreated separately with specific inhibitors of MAPKs, including extracellular signal-regulated kinase, p38 MAPK and c-Jun N-terminal kinase, and subsequently treated with interleukin-1beta. Following each treatment, the phosphorylation of each MAPK, the expression of RANKL, and the production of prostaglandin E2 were determined. RANKL activity was evaluated using an assay to determine the survival of prefusion osteoclasts.

RESULTS

Interleukin-1beta induced RANKL expression at the mRNA and protein levels, as well as RANKL activity in human periodontal ligament cells. Interleukin-1beta also activated extracellular signal-regulated kinase, p38 MAPK, and c-Jun N-terminal kinase. Pretreatment with each MAPK inhibitor partially, but significantly, suppressed interleukin-1beta-induced RANKL expression and its activity, as well as prostaglandin E2 production.

CONCLUSION

In human periodontal ligament cells, three types of MAPK inhibitor may abrogate RANKL expression and activity induced by interleukin-1beta, directly or indirectly through partial suppression of prostaglandin E2 synthesis. In addition, extracellular signal-regulated kinase, p38 MAPK, and c-Jun N-terminal kinase signals may co-operatively mediate interleukin-1beta-stimulated RANKL expression and its activity in those cells.

Levels of gingival tissue platelet activating factor after conventional and regenerative periodontal surgery

The hypothesis, a relationship between gingival tissue platelet activating factor (PAF) levels and healing after periodontal surgery, was tested by measuring PAF levels in gingival tissues collected from sites that had undergone flap surgery and guided tissue regeneration (GTR) or flap surgery alone. Using a split-mouth design, 20 intrabony defects were randomly assigned to treatment with flap surgery and GTR (group 1) or with flap surgery alone (group 2). Gingival tissue samples were obtained at surgery (baseline) and at 6-month follow-up evaluation visit. One half of each sample was used for analysis of PAF levels by high-performance liquid chromatography, and the other half of the sample was used for histomorphometric analysis that included measurements of number and diameter of blood vessels. PAF levels and diameter of blood vessels were significantly decreased (p < 0.01), and the number of blood vessels was significantly increased (p < 0.05) in both groups after 6 months compared to the baseline values. Postoperative number of blood vessels were significantly higher in group 1 (p < 0.05), whereas there was no significant difference in postoperative PAF levels between the two groups (p > 0.05). Based on the reported results, it is suggested that a decrease in gingival PAF levels might be found after conventional and regenerative periodontal surgery.

Citation classics in periodontology: a controlled study

AIM

The aims of this study were to identify the most cited articles in Periodontology published from January 1990 to March 2005; and to analyse the differences between citation Classics and less cited articles.

MATERIAL AND METHODS

The search was carried out in four international periodontal journals: Journal of Periodontology, Journal of Clinical Periodontology, International Journal of Periodontics and Restorative Dentistry and Journal of Periodontal Research. The Classics, that are articles cited at least 100 times, were identified using the Science Citation Index database. From every issue of the journals that contained a Classic, another article was randomly selected and used as a Control.

RESULTS

Fifty-five Classics and 55 Controls were identified. Classic articles were longer, used more images, had more authors, and contained more self-references than Controls. Moreover Classics had on the average a bigger sample size, often dealt with etiopathogenesis and prognosis, but were rarely controlled or randomized studies.

CONCLUSIONS

Classic articles play an instructive role, but are often non-Controlled studies.

Interleukin-4 inhibition of interleukin-1-induced expression of matrix metalloproteinase-3 (MMP-3) is independent of lipoxygenase and PPARgamma activation in human gingival fibroblasts

Background

Interleukin 4 (IL-4) has been shown to suppress interleukin-1 (IL-1) induced expression of matrix metalloproteinase-3 (MMP-3) in human synovial and gingival fibroblasts, but the mechanism of suppression has not been determined. Activators of peroxisome proliferator-activated receptor-γ (PPARγ) have been shown to inhibit cytokine induced expression of MMPs in other cell types, and IL-4 has been shown to activate PPARγ by stimulating production of ligands through the lipoxygenase pathway. It has been suggested that PPARγ may inhibit expression of MMPs by competing with transcription factor AP-1 for binding to a putative composite binding element in the promoters. The objective of this study was to determine whether the suppressive effects of IL-4 on the IL-1 induced expression of MMP-3 involve activation of lipoxygenase and/or PPARγ.

Results

Western blotting revealed the presence of PPARγ in nuclear extract of HGF. IL-1 induced binding of nuclear extract to the putative composite PPRE/AP-1 site was diminished in the presence of pioglitazone, but there was no evidence of any change in the composition of the retarded complexes, and no evidence of PPARγ binding to this site. Nordihydroguaiaretic acid (NDGA), a non-selective lipoxygenase inhibitor, and MK886, a specific inhibitor of 5-lipoxygenase, induced MMP-3 expression synergistically with IL-1. However IL-4 was still able to inhibit MMP-3 expression in the presence of NDGA or MK886 and IL-1. Activation of PPARγ with pioglitazone not only failed to inhibit IL-1 induced expression of MMP-3 mRNA, but rather super-induced MMP-3 in the presence of IL-1. PPARγ antagonist GW9662 failed to abolish the suppressive effects of IL-4. Another PPARγ activator, 15-deoxy-Delta12,14prostaglandin J2 (15dPGJ2), also super-induced MMP-3 mRNA, and this was due at least in part to increased transcription.

Conclusion

IL-4 suppression of IL-1-induced MMP-3 expression in HGF is independent of lipoxygenase activity and activation of PPARγ. Super-induction of MMP-3 by pioglitazone may have important implications for patients using pioglitazone to treat type II diabetes in the presence of chronic inflammation.

In vitro anti-microbial and in vivo cytokine modulating effects of different prepared Chinese herbal medicines

The toxicity, antimicrobial and cytokine modulating effects of herbal medicines in treating periodontal diseases were evaluated in this study. Using the broth dilution method and disc agar diffusion test, in individual and combined decocted preparations, different concentrations of Ching-Wei-San and its individual herbal components, Coptidis rhizoma, Angelicae sinensis radix, Rehmanniae radixet rhizom, Moutan radicis cortex, and Cimicifuga foetida, were tested for in vitro inhibitory effects on three well-known plaque-causing bacteria, Porphyromonas gingivialis, Streptococcus sanguis, and Streptococcus mutans, and two common pathogens, Staphylococcus aureus and Escherichia coli. The cytokine modulating effects were evaluated in Balb/c mice. The results suggested that one milliliter Ching-Wei-San at the 25,000 mg/mL concentration daily for the mice had significantly high levels in the liver function indexes in the 3-day acute toxicity test and in both the liver and kidney function indexes in the 28-day subacute toxicity test (P<0.01). The 250 mg/mL Ching-Wei-San is comparable to 250 mg/mL of tetracycline, and had similar inhibitory effects on the tested bacteria. Coptidis rhizoma (62.5 mg/mL) was the only individual herbal component to show 100% inhibitory effects. The mean cytokine ratios of IL-2, IL-4, IFN-gamma, and TNF-alpha in Balb/c mice treated with individual herbal components were shown to be different from each other. Ching-Wei-San modulated the immunity of mice, up-regulated IL-2, IL-4 and TNF-alpha, but down-regulated IFN-gamma. The effects of none of the individual herbal components alone can substitute for the cumulative effect of Ching-Wei-San.

Expression of beta-defensin-2 in human gingival epithelial cells in response to challenge with Porphyromonas gingivalis in vitro

BACKGROUND AND OBJECTIVE

Human beta-defensin-2 (hBD-2) is an antimicrobial peptide that is produced by epithelial cells after stimulation with microorganisms and inflammatory mediators. Compared with gram-positive bacteria, gram-negative bacteria, which are typically detected in the periodontal pockets in periodontitis, elicit a stronger antibacterial peptide response of hBD-2 by epithelial cells. The purpose of this study was to investigate the expression of hBD-2 and relationships between it and inflammatory mediators in human gingival epithelial cells (HGEC) in response to challenge with Porphyromonas gingivalis in vitro.

MATERIAL AND METHODS

mRNA expression of hBD-2 in HGEC stimulated with or without P. gingivalis was assessed using a semiquantitative reverse transcription-polymerase chain reaction. Primary cultured HGEC were activated by live P. gingivalis, and inflammatory cytokine production was examined using an enzyme-linked immunosorbent assay.

RESULTS

The level of hBD-2 mRNA in HGEC treated with P. gingivalis increased with exposure time. After 48 h, the mRNA in P. gingivalis was significantly increased compared with that in control HGEC. The interleukin-8 production rate was much greater in stimulated HGEC than in the control HGEC, almost always showing a significant difference after 3 h. The production of interleukin-1beta was not increased as much as that of interleukin-8.

CONCLUSION

These findings suggest that the expression of hBD-2 in HGEC is P. gingivalis-dependently induced and is likely to be connected with the initial stage of the inflammatory response.

Assessment of single nucleotide polymorphism at IL-1A+4845 and IL-1B+3954 as genetic susceptibility test for chronic periodontitis in Maharashtrian ethnicity

BACKGROUND

The inflammatory response that is directed in large part by proinflammatory cytokine interleukin (IL)-1 is genetically determined, with some people having a more vigorous response than others to the same stimulus. The reason for this is speculated that the dysregulated production of IL-1 in some individuals overrides the feedback mechanisms that normally master the dose of inflammation to a level sufficient to fight microbial invasion without long-lasting damage to the tissues involved. The aims of the present study were to determine the distribution of IL-1 gene polymorphism (IL-1A+4845 and IL-1B+3954) and their association with periodontal disease severity and to determine the significance of detecting the composite genotype (IL-1A allele2+IL-1B allele2) versus detecting either of them alone.

METHODS

A total of 120 subjects were included and divided into four groups of 30 subjects each, namely, healthy, mild, moderate, and severe periodontitis groups. After a complete clinical examination, DNA was isolated from 0.5 ml blood. Specific primers were used to detect the presence of IL-1 gene polymorphism with the help of polymerase chain reaction (PCR) and subsequent allele detection with restriction fragment length polymorphism (RFLP) and separation by gel electrophoresis.

RESULTS

The distribution of the allele1 homozygous genotype was 3% in the severe periodontitis group, and the distribution for the allele2 genotype was 30%. A higly significant difference (Wilcoxon signed-rank test; P<0.001) was seen between subjects positive and negative for the composite genotype.

CONCLUSIONS

Results of the present study reinforced the association of the IL-1 genotype as a risk factor for severe chronic periodontitis. Positivity for the composite genotype was found to be significantly associated with severe chronic periodontitis (odds ratio [OR]=12.42).

Simvastatin decreases IL-6 and IL-8 production in epithelial cells

Many cardiovascular studies have suggested that 3-hydroxy-3-methylglutaryl co-enzyme A reductase inhibitors (statins) have anti-inflammatory effects independent of cholesterol lowering. As a chronic inflammatory disease, periodontitis shares some mechanisms with atherosclerosis. Since oral epithelial cells participate importantly in periodontal inflammation, we measured simvastatin effects on interleukin-6 and interleukin-8 production by cultured human epithelial cell line (KB cells) in response to interleukin-1alpha. Simvastatin decreased production, an effect reversed by adding mevalonate or geranylgeranyl pyrophosphate, but not farnesyl pyrophosphate. Simvastatin was found to reduce NF-kappaB and AP-1 promoter activity in KB cells. Dominant-negative Rac1 severely inhibited interleukin-1alpha-induced NF-kappaB and AP-1 promoter activity. Our results may indicate an anti-inflammatory effect of simvastatin on human oral epithelial cells, apparently involving Rac1 GTPase inhibition.