LPS-elicited secretory responses in monocytes: altered release of PGE2 but not IL-1 beta in patients with adult periodontitis

Nicotine in Inflammatory Diseases: Anti-Inflammatory and Pro-Inflammatory Effects

As an anti-inflammatory alkaloid, nicotine plays dual roles in treating diseases. Here we reviewed the anti-inflammatory and pro-inflammatory effects of nicotine on inflammatory diseases, including inflammatory bowel disease, arthritis, multiple sclerosis, sepsis, endotoxemia, myocarditis, oral/skin/muscle inflammation, etc., mainly concerning the administration methods, different models, therapeutic concentration and duration, and relevant organs and tissues. According to the data analysis from recent studies in the past 20 years, nicotine exerts much more anti-inflammatory effects than pro-inflammatory ones, especially in ulcerative colitis, arthritis, sepsis, and endotoxemia. On the other hand, in oral inflammation, nicotine promotes and aggravates some diseases such as periodontitis and gingivitis, especially when there are harmful microorganisms in the oral cavity. We also carefully analyzed the nicotine dosage to determine its safe and effective range. Furthermore, we summarized the molecular mechanism of nicotine in these inflammatory diseases through regulating immune cells, immune factors, and the vagus and acetylcholinergic anti-inflammatory pathways. By balancing the “beneficial” and “harmful” effects of nicotine, it is meaningful to explore the effective medical value of nicotine and open up new horizons for remedying acute and chronic inflammation in humans.

Humic Acid, a Polyphenolic Substance, Decreases Alveolar Bone Loss in Experimental Periodontitis in Rats

The purpose of this study was to evaluate the biochemical, morphometric, and histopathological changes associated with experimental periodontitis in rats in response to local administration of humic acid. Thirty-eight Wistar rats were divided into 5 experimental groups: nonligated (NL) group, ligature-only (LO) group, and ligature + local administration of humic acid (20, 80, and 150 mg/kg body weight per day for 15 days, respectively; L-20, L-80, and L-150 groups). Changes in alveolar bone levels were clinically measured as the distance from the cementoenamel junction to the alveolar bone crest with a stereomicroscope. Tissues were histopathologically examined to assess the osteoclast numbers, osteoblastic activity, and inflammatory cell infiltration among the study groups. Enzyme-linked immunosorbent assay interleukin1β (IL-1β) and IL-10 levels in serum and gingival homogenates were evaluated. At the end of 15 days, the alveolar bone loss was significantly higher in the LO group compared to the NL, L-20, and L-150 groups (P < .05). The osteoclast number in the LO group was significantly higher than the NL, L-20, and L-150 groups (P < .05). Inflammatory cell infiltration was significantly higher in the LO and L-80 groups than the other groups (P < .05). The highest serum and gingival homogenate IL-10 levels were determined in the NL group (P < .05). The serum and gingival homogenate IL-1β levels in LO group were significantly higher than the NL, L-20, and L-150 groups (P < .05). Within the limits of this study, it can be suggested that humic acid, when administered locally at 20 and 80 mg/kg doses, may prevent alveolar bone loss in the rat model.

Gingival crevicular fluid levels of monocyte chemoattractant protein-1 in patients with aggressive periodontitis

OBJECTIVES

The purpose of this study was to investigate the gingival crevicular fluid (GCF) levels of monocyte chemoattractant protein (MCP)-1 in aggressive periodontitis (AgP) and whether GCF MCP-1 levels differ among localized (L) AgP and generalized (G) AgP.

MATERIAL AND METHODS

A total of 160 subjects including 80 AgP and 80 age- and gender-matched periodontally healthy (H) controls were recruited in this cross-sectional study (NCT02927704). GCF samples were collected from 160 patients including 50 LAgP, 30 GAgP, and 80 H. Volume of GCF was measured by Periotron 8000^® , and enzyme-linked immunosorbent assay was used to assess MCP-1 levels.

RESULTS

Compared to H controls, all clinical parameters and total amounts (pg 30 s^-1 ) of MCP-1 were significantly higher in subjects with LAgP and GAgP (P < 0.05). Although concentrations of GCF MCP-1 did not differ between LAgP and GAgP (P > 0.05), total amounts of MCP-1 were higher in GAgP than LAgP (P < 0.05).

CONCLUSION

It can be concluded that the total amount of MCP-1 level in GCF may be a potential determinant in AgP subjects. Increased MCP-1 levels in line with the degree of periodontal destruction in GAgP patients reveal that MCP-1 can be used to understand the disease pathogenesis of LAgP and GAgP.

Comparison of the proportion of non-classic (CD14+CD16+) monocytes/macrophages in peripheral blood and gingiva of healthy individuals and patients with chronic periodontitis

BACKGROUND

Monocyte subsets with low CD14 expression that coexpress CD16 (CD14+CD16+) are called non-classic or hyperinflammatory monocytes. Previous studies have reported an increase in the percentage of CD14+CD16+ monocytes in the peripheral blood of patients with chronic periodontitis (CP). To our knowledge, there are no reports demonstrating the presence of CD14+CD16+ monocyte-derived macrophages (MDMs) in the gingival tissue. The objective of this study is to identify the proportion of non-classic (CD14+CD16+) monocytes/macrophages in peripheral blood and gingiva of healthy individuals and patients with CP.

METHODS

A total of 60 individuals (n = 30 per group) were recruited for the study. Group 1 included 30 individuals with healthy gingiva, and group 2 included 30 patients with CP. Direct immunofluorescent staining was done in 200 μL whole-blood and single-cell suspensions obtained from gingival tissue, with fluorochrome-conjugated monoclonal antibodies against CD14, CD16, and human leukocyte antigen-DR (HLA-DR), and subjected to flow cytometric analysis.

RESULTS

The mean percentage of CD14+CD16+ monocytes in the peripheral blood of healthy individuals was 9.10% ± 1.39%, and for patients with CP it was 14.18% ± 2.69% (P <0.05). The mean percentage of CD14+CD16+ MDMs in the gingival tissue of healthy individuals was found to be 0.93% ± 0.33%, whereas in patients with CP, it was 1.92% ± 0.78% (P <0.01). Non-classic monocytes/macrophages showed a high median fluorescent intensity for HLA-DR (DR++).

CONCLUSION

This study demonstrates an increased proportion of CD14+CD16+HLA-DR++ monocytes/macrophages in the peripheral blood and gingiva of patients with CP.

Development of animal experimental periodontitis models

Purpose

An animal periodontitis model is essential for research on the pathogenesis and treatment of periodontal disease. In this study, we have introduced a lipopolysaccharide (LPS) of a periodontal pathogen to the alveolar bone defect of experimental animals and investigated its suitability as a periodontitis model.

Methods

Alveolar bone defects were made in both sides of the mandibular third premolar region of nine beagle dogs. Then, the animals were divided into the following groups: silk ligature tied on the cervical region of tooth group, Porphyromonas gingivalis LPS (P.g. LPS)-saturated collagen with silk ligature group, and no ligature or P.g. LPS application group as the control. The plaque index and gingival index were measured at 0 and 4 weeks postoperatively. The animals were then euthanized and prepared for histologic evaluation.

Results

The silk ligature group and P.g. LPS with silk ligature group showed a significantly higher plaque index at 4 weeks compared to the control (P<0.05). No significant difference was found in the plaque index between the silk ligature group and P.g. LPS with silk ligature group. The P.g. LPS with silk ligature group showed a significantly higher gingival index compared to the silk ligature group or the control at 4 weeks (P<0.05). Histologic examination presented increased inflammatory cell infiltration in the gingival tissue and alveolar bone of the P.g. LPS with silk ligature group.

Conclusions

An additional P.g. LPS-saturated collagen with silk ligature ensured periodontal inflammation at 4 weeks. Therefore, P.g. LPS with silk ligature application to surgically created alveolar bone defects may be a candidate model for experimental periodontitis.

Association between chronic periodontitis and rheumatoid arthritis: a hospital-based case-control study

Rheumatoid arthritis (RA) and chronic periodontitis are the most common chronic inflammatory diseases with remarkable pathological and clinical similarities. A lot of similarities exist between RA and periodontitis at cellular and molecular levels. The relationship between these two chronic inflammatory diseases is still unclear. This case-control study was undertaken to determine the possible association between chronic inflammatory diseases like RA and periodontitis. The case group consisted of 100 patients attending the Rheumatology clinic who have rheumatoid arthritis (RA group). Age- and gender-matched 112 patients without RA attending the Outpatient wing of Department of General Medicine formed the control group (NRA group). The number of missing teeth, gingival index (GI), oral hygiene index-simplified (OHI-S), probing pocket depth (PPD) and clinical attachment levels (CAL) were evaluated in both the groups. Rheumatoid disease activity was assessed by DAS-28 score system. Systemic markers of inflammation like erythrocytic sedimentation rate (ESR) and serum levels of C-reactive protein (CRP) were assessed. There was a statistically significant difference in GI, OHI-S, PPD, CAL, ESR and CRP levels between cases (RA group) and controls (NRA group) (P < 0.05). Among subjects with RA, there was no association between the rheumatoid disease activity and the severity of periodontal disease. The occurrence and severity of periodontitis was found to be higher in RA subjects as compared to subjects without RA, suggesting a positive relation between these two chronic inflammatory diseases.

The effect of ketoprofen in chronic periodontitis: A clinical double-blind study

Background:

The objective of this double-blind clinical trial was to evaluate the effects of the nonsteroidal anti-inflammatory drug (NSAID), ketoprofen, on patients with chronic periodontitis.

Materials and Methods:

Two similar local drug delivery preparations of a poloxamen gel containing 1.5% ketoprofen and a placebo were indigenously prepared for this purpose. Ten subjects aged 33-55 years with moderate to severe chronic periodontitis were recruited and were monitored for a period of 90 days. Three sites in each patient (total 30 sites) with a probing pocket depth of 5-8 mm were selected and divided randomly into three groups: 1) group A: scaling and rootplaning (SRP) + drug A; 2) group B: SRP + drug B; and 3) group C: SRP. Clinical parameters and blood smear (from intracrevicular blood) were assessed to determine the differential count and Arneth index. All parameters were assessed at baseline, 30 days and 90 days, respectively.

Results:

Highly significant values were achieved for plaque index (P=0.00), and significant values were obtained for gingival index (P=0.044). Reduction in bleeding on probing was found to be highly significant. Probing depth and clinical attachment level showed no inter group variation.

Conclusion:

The results of this double-blind trial indicate that the combined effect of locally delivered ketoprofen with SRP was more effective in controlling periodontal disease than SRP alone.

Anti-inflammatory effects of apigenin on nicotine- and lipopolysaccharide-stimulated human periodontal ligament cells via heme oxygenase-1

BACKGROUND AND OBJECTIVES

Although apigenin exhibits various biological effects, its anti-inflammatory role in the periodontal field remains unknown. We examined the anti-inflammatory effects of apigenin and the underlying mechanism in nicotine- and lipopolysaccharide (LPS)-stimulated human periodontal ligament (hPDL) cells.

MATERIALS AND METHODS

Western blotting was used to examine the effect of apigenin (10-40 microM) on the LPS- and nicotine-induced expression of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and heme oxygenase-1 (HO-1), as well as the phosphorylation of mitogen-activated protein kinases (MAPKs), in hPDL cells. Pro-inflammatory mediators, including nitric oxide (NO), prostaglandin E2 (PGE2), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), IL-6, and IL-12 were monitored using Griess reagents and ELISA.

RESULTS

Incubation of hPDL cells with apigenin decreased LPS- and nicotine-induced HO-1 protein expression and activity. Apigenin significantly inhibited the nicotine- and LPS-induced production of NO, PGE2, IL-1beta, TNF-alpha, IL-6, and IL-12, and the upregulation of iNOS and COX-2 in hPDL cells. Hemin, a selective HO-1 inducer, reversed the apigenin-mediated suppression of nicotine- and LPS-induced NO, PGE2 and cytokine production. Treatment with inhibitors of the phosphoinositide 3-kinase, MAPKs, p38, and JNK, as well as a protein kinase C inhibitor, blocked the anti-inflammatory effects of apigenin in nicotine- and LPS-treated cells.

CONCLUSIONS

Apigenin possesses anti-inflammatory activity in hPDL cells and works through a novel mechanism involving the action of HO-1. Thus, apigenin may have potential benefits as a host modulatory agent in the prevention and treatment of periodontal disease associated with smoking and dental plaque.

Gingival levels of monocyte chemoattractant protein-1 (MCP-1) in diabetes mellitus and periodontitis: an experimental study in rats

The objectives of this study were to investigate and compare the monocyte chemoattractant protein-1 (MCP-1) levels of gingival tissues in diabetes mellitus (DM) and periodontitis and to reveal the effects of MCP-1 on periodontal inflammation and destruction in these diseases. DM was created in 15 rats (group 1) by streptozotocin injection, and periodontitis was obtained by ligature induction in 15 rats (group 2). Fifteen systemically and periodontally healthy rats were used as control (group 3). Gingival MCP-1 levels were measured by enzyme-linked immunosorbent assay (ELISA). Periodontal inflammation was quantified by the inflammatory cell infiltration in the gingival samples, whereas periodontal destruction was assessed by the alveolar bone loss in the experimental regions. MCP-1 concentrations were higher in groups 1 and 2 than in group 3 (p < 0.001). Increased gingival inflammatory cell infiltration and alveolar bone loss were observed in groups 1 and 2 compared to group 3 (p < 0.001). There were positive correlations among the MCP-1 level, gingival inflammatory cell infiltration, and alveolar bone loss in groups 1 and 2 (p < 0.001). Our results suggest that (1) DM may lead to enhanced MCP-1 production in periodontal tissues likewise for periodontitis and (2) there may be a positive correlation between the MCP-1 concentration and diseased nature of periodontium in both diseases.

Hyper-reactive mononuclear cells and neutrophils in chronic periodontitis

OBJECTIVES

Stimulated mono- and polymorphonuclear cells from patients with periodontitis have shown increased release of interleukin-1beta (IL-1beta) and oxygen radicals, respectively. The aim was to study whether this hyper-reactivity could be found both in mono- and polymorphonuclear cells from the same patient, and whether there was a relation to the gene coding for IL-1beta (IL-1beta(+3953)).

MATERIAL AND METHODS

Peripheral mononuclear cells from 14 non-smoking and well-treated patients and pair-matched controls were incubated with opsonized Staphylococcus aureus and lipopolysaccharide (LPS). Released IL-1beta and tumour necrosis factor (TNF)-alpha were determined with ELISA. Generation of oxygen radicals from the Fcgamma-receptor-stimulated neutrophils was measured with chemiluminescence and the polymorphism at IL-1beta(+3953) was measured with polymerase chainreaction.

RESULTS

The mononuclear cells from the patients released more IL-1beta after incubation with LPS (p<0.001) and with bacteria (p<0.05). The release of TNF-alpha tended to be higher in the patient group. The peripheral neutrophils from the patients generated more oxygen radicals (p<0.06). We found no differences between the study groups regarding the IL-1beta(+3953) polymorphism.

CONCLUSION

The similarity in systemic inflammation between patients and controls suggests that the increased release/generation of IL-1beta and oxygen radicals from peripheral leukocytes in periodontitis patients is of a constitutional nature and of pathogenic relevance.

Effect of genetic variability on the inflammatory response to periodontal infection

AIM

To review the association between genetic variability and the inflammatory response induced by periodontal infection.

MATERIAL AND METHODS

A search of MEDLINE-PubMed was performed from January 2000 up to and including March 2005. The search included all types of publications, published in English without other limitations. The following search terms were used: "cytokine polymorphism", "gene polymorphism", "periodontitis", "gingivitis", "inflammation" and "host-response". The papers resulting from the above search were used as an additional source for relevant articles.

RESULTS

Genetic variability was examined for the correlation to clinical indicators of inflammation such as bleeding on probing (BOP), gingival inflammation, cytokine in gingival crevicular fluid (GCF) and cytokine production by inflammatory cells. According to the current literature, most of the studies found no association between genetic variability and BOP, gingival inflammation or cytokine concentrations in the GCF. These studies were hampered by inappropriate study designs and the use of inflammatory parameters as secondary rather than primary outcome variables. The data suggest that the production of inflammatory mediators by inflammatory cells may be affected by different genetic traits but further studies are needed in order to establish this association.

CONCLUSIONS

To date, there is no clear correlation between any of the gene polymorphisms and clinical indicators of inflammation. The powering of studies to reveal associations between single or multiple nucleotide polymorphisms and inflammatory parameters will need to involve a much larger number of subjects than were used in the past. The available data (including the interleukin-1 composite genotype) do not currently support the utility of such tests in the diagnosis and prognostic assessments of periodontal diseases.

Gingival crevicular fluid EMAP-II, MIP-1alpha and MIP-1beta levels of patients with periodontal disease

BACKGROUND

Periodontal diseases may differ, which could be attributed to the factors that might modify the host response to microbial pathogens. The aim of this study was to examine gingival crevicular fluid (GCF) levels of EMAP-II, MIP-1alpha and MIP-1beta in patients with different periodontal diseases (EMAP-II, endothelial-monocyte activating polypeptide; MIP-1alpha, macrophage inflammatory protein-1alpha; MIP-1beta, macrophage inflammatory protein-1beta).

METHODS

Eighty-two subjects were included in this study. GCF samples were collected from 26 patients with generalized aggressive periodontitis (G-AgP), 26 patients with chronic periodontitis (CP), 15 with gingivitis and 15 periodontally healthy subjects. Clinical periodontal parameters were recorded. GCF EMAP-II, MIP-1alpha and MIP-1beta levels were quantified by enzyme immunoassay.

RESULTS

GCF EMAP-II levels of G-AgP group were higher than those of gingivitis and healthy groups (p<0.008). G-AgP group showed a trend for higher GCF EMAP-II levels compared with CP group (p>0.008). G-AgP, CP, gingivitis and healthy groups had comparable GCF MIP-1alpha and MIP-1beta levels.

CONCLUSIONS

Our results suggest that elevated GCF EMAP-II could contribute to the pathogenesis of G-AgP. Alternatively, EMAP-II reflects the extent of the inflammatory activity in the periodontal tissues. At this point, MIP-1alpha and MIP-1beta levels in GCF do not seem to play a discriminatory role in periodontitis. Our data document for the first time the essential role of EMAP-II in the pathogenesis of different periodontal diseases.

Gingival crevicular fluid monocyte chemoattractant protein-1 and RANTES levels in patients with generalized aggressive periodontitis

BACKGROUND

Local and systemic inflammatory and immune mechanisms may be implicated in the pathogenesis of the aggressive forms of periodontal disease. Chemokines, monocyte chemoattractant protein-1 (MCP-1) and regulated on activation, normal T cells expressed and secreted RANTES (regulated on activation, normal T cells expressed and secreted), are involved in the activation and recruitment of inflammatory and immune cells to the infected sites and thereby mediating a variety of pathophysiological conditions. The aim of the present study was to examine the gingival crevicular fluid (GCF) levels of MCP-1 and RANTES in patients with generalized agressive periodontitis (G-AgP).

METHODS

MCP-1 and RANTES levels were investigated in GCF samples of 10 patients with G-AgP and 10 periodontally healthy subjects. Periodontal status was evaluated by measuring probing depth, clinical attachment loss, presence of bleeding on probing and plaque. In the G-AgP group, GCF samples were collected from the two approximal sites; from one single-rooted tooth and from one first molar tooth with > or =6 mm probing depth. In the healthy group, GCF samples were collected from one of the single-rooted teeth. GCF MCP-1 and RANTES levels were quantified by enzyme immunoassay.

RESULTS

The G-AgP patients had significantly higher GCF MCP-1 and RANTES levels compared to the healthy group (p<0.05). GCF MCP-1 and RANTES levels were positively correlated with both probing depth and clinical attachment loss (p<0.05). There was no correlation between GCF MCP-1 and RANTES levels and the percentage of sites with bleeding (p>0.05).

CONCLUSIONS

The results of the present study suggest that MCP-1 and RANTES could play key roles in both activation and recruitment of inflammatory and immune cells in periodontal environment of G-AgP patients. In conclusion, these CC chemokines may be considered in the biological mechanism underlying the pathogenesis and progression of G-AgP.

A model of periodontitis in the rat: effect of lipopolysaccharide on bone resorption, osteoclast activity, and local peptidergic innervation

OBJECTIVE

To establish and characterise a rat model of periodontitis that reiterates the features of human disease.

METHODS

Periodontal inflammation was induced by a single injection of 10 microg liposaccharide (LPS) (Salmonella typhimurium) in 1 microl saline into rat mandibular gingiva at the buccomesial aspect of the second molar. Animals were killed after 3, 7 and 10 days, mandibles dissected and sectioned for histological and immunocytochemical analysis.

RESULTS

LPS injection resulted in a significant gingival and periodontal inflammation with inflammatory infiltrate, apical migration of the junctional epithelium, interdental bone loss, and activation of osteoclasts at the site of injection 7 and 10 days after injection. At 10 days post injection, there was a significant trend for bone loss on both sides of the mandible. Periodontal inflammation was associated with alteration in the levels of calcitonin gene-related peptide-like immunoreactivity in nerve terminals innervating the inflamed gingival papilla.

CONCLUSION

Intragingival injection of LPS in the rat provides an easily induced reproducible experimental model of periodontal inflammation that reiterates features of human disease.

Immuno-localization of COX-1 and COX-2 in the rat molar periodontal tissue after topical application of lipopolysaccharide

Up-regulation of prostaglandin E2 (PGE2) production in the periodontal tissue is considered to be important for periodontal tissue destruction. The purpose of the study was to demonstrate the dynamic changes of immuno-localization of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) in rat periodontal tissue after topical application of lipopolysaccharide (LPS: 5 mg/ml in physiological saline) from Escherichia coli into the rat molar gingival sulcus. In the normal periodontal tissue, small numbers of junctional epithelium (JE) cells and numerous osteocytes embedded in alveolar bone constitutively expressed COX-1. The COX-1 expression was not effected by LPS application. JE cells, especially in the coronal portion of JE also expressed COX-2. LPS application induced the JE cells with consequent transient expression of COX-2 with a peak at day 1. These findings suggest that JE cells may play a critical role in first defense line against LPS challenge and PGE2 from JE cells may be responsible for the initiation of periodontal inflammation. In the deep periodontal tissue, cementoblasts and osteoblasts showed constitutive expression of COX-2, which may be induced by continuous cyclic tension force due to occlusal pressure. LPS application caused a transient up-regulation of COX-2 expression in periodontal ligament fibroblasts, cementoblasts and osteoblasts. It is suggested that the inducible production of PGE2 via COX-2 by these cells may be associated with connective tissue destruction and alveolar bone resorption.

Monocyte activation by Porphyromonas gingivalis LPS in aggressive periodontitis with the use of whole-blood cultures

In this study, we re-visited the issue of hyper-responsiveness of monocytes to bacterial lipopolysaccharide (LPS) in aggressive periodontitis patients. We used whole-blood cultures to compare monocyte activation by Porphyromonas gingivalis LPS between Thai subjects with generalized aggressive periodontitis and those without periodontitis. Upon stimulation with P. gingivalis LPS, expression of co-stimulatory molecules on monocytes and expression of CD69 on NK and gamma delta T-cells were analyzed by flow cytometry, and the production of interleukin-1 beta and prostaglandin E(2) was monitored by ELISA. LPS stimulation resulted in a dose-dependent up-regulation of CD40, CD80, and CD86 on monocytes, and up-regulation of CD69 on NK cells and gamma delta T-cells in both the periodontitis and non-periodontitis groups. The levels of activation markers and the mediator production after LPS stimulation were quite similar for both groups. In conclusion, we did not observe hyper-responsiveness of monocytes to P. gingivalis LPS challenge in Thai patients with aggressive periodontitis.

Inter-relationships between rheumatoid arthritis and periodontal disease. A review

This review considers the considerable similarities between periodontal disease and rheumatoid arthritis (RA). While the etiology of these two diseases may differ, the underlying pathogenic mechanisms are remarkably similar and it is possible that individuals manifesting both periodontitis and RA may suffer from a unifying underlying systemic dysregulation of the inflammatory response. In light of these findings, the implications for the use of disease-modifying medications in the management of these two chronic inflammatory conditions is apparent. Further longitudinal studies and medication-based intervention studies are required to determine just how closely these two conditions are allied.

Enhanced levels of prostaglandin E2, leukotriene B4, and matrix metalloproteinase-9 in gingival crevicular fluid from patients with Down syndrome

The aim was to study the levels of prostaglandin E2 (PGE2), leukotriene B4 (LTB4), and matrix metalloproteinase-9 (MMP-9) in gingival crevicular fluid (GCF) from Down syndrome patients exhibiting gingival inflammation. The levels of PGE2, LTB4, and MMP-9 were determined in GCF from 18 Down syndrome patients and from 14 controls matched with respect to age and degree of gingival inflammation. Probing depth (PD) and gingival inflammation, assessed by bleeding on probing (BOP), were determined around all teeth. In each patient, GCF was collected from 6 sites (16m, 26m, 36m, 46m, 41m, 11d) using periopaper, and the volume was determined using Peritron 8000. The PGE2 and LTB4 levels were determined using RIA kits and MMP-9 level using ELISA kits. The degree of gingival inflammation, expressed as mean value of BOP (%) as well as the volume of GCF, was similar between Down syndrome patients and controls. The mean levels of PGE2, LTB4, and MMP-9 were significantly (P<0.05) higher in GCF from Down syndrome patients compared to controls. When comparing the two groups, the correlation coefficients for LTB4 to BOP and PD, respectively, as well as for MMP-9 to BOP significantly differed between Down syndrome and controls (P<0.05). The study supports the concept of an altered host response in periodontal tissue in Down syndrome subjects.

Porphyromonas gingivalis antigen preferentially stimulates T cells to express IL-17 but not receptor activator of NF-kappaB ligand in vitro

Although T cells have been implicated in the pathogenesis and are considered to be central to both their progression and control of chronic inflammatory periodontal diseases, the precise contribution of T cells to tissue destruction has not been fully clarified. Recently, interleukin (IL)-17 and receptor activator of Nuclear factor kappaB NF-kappaB ligand (RANKL) have received much attention as a result of their proinflammatory and bone metabolic roles, respectively. We therefore investigated the effect of outer membrane protein (OMP) from Porphyromonas gingivalis (P. gingivalis) on the expression of IL-17 and RANKL in peripheral blood mononuclear cells (PBMCs) and compared these between gingivitis and periodontitis, which are representative of stable and progressive lesions, respectively. The in situ expression of these molecules was also examined. P. gingivalis OMP stimulated PBMCs to express IL-17 at both the mRNA and protein level. Although the mean expression of mRNA was not different between the two groups, the mean level of IL-17 in the culture supernatants was higher in gingivitis patients than in periodontitis patients. However, the frequency of IL-17-positive samples was higher in the periodontitis patients. This stimulatory effect was not evident for RANKL expression in either periodontitis or gingivitis patients. In gingival tissue samples, IL-17 mRNA was detected in gingivitis more frequently than in periodontitis. The expression of RANKL mRNA was much lower than that of IL-17 in terms of both level and frequency. These results suggest that IL-17 but not RANKL may be involved in the pathogenesis of periodontal diseases. However, there may be negative regulatory mechanisms for IL-17 in gingivitis.

HLA-A, B, Cw, DRB1, DRB3/4/5, DQB1 in German patients suffering from rapidly progressive periodontitis (RPP) and adult periodontitis (AP)

BACKGROUND/AIM

There is growing indication that differences in host response determine susceptibility and resistance to periodontal disease. Particularly, the effect of histocompatibility antigens (HLA) on early onset periodontitis (EOP) has been studied. As most of the results are not conclusive and to date no report has been done on German patients, the aim of this study was to investigate the distribution of HLA alleles in a group of 50 German RPP patients and 102 German AP patients and to compare them to 102 control probands without periodontitis.

METHODS

Diagnosis was established according to standardised clinical criteria. HLA typing was performed using serologic and molecular biologic (PCR-SSP) techniques.

RESULTS

Compared to the controls, RPP patients had a significantly higher frequency of HLA-DRB1*13 and a significantly lower frequency of HLA-DRBblank*(non-DRB3/4/5). AP patients showed a significantly increased occurrence of HLA-B*14 and -Cw*08 as well as a significantly decreased frequency of HLA-A*03. In both patient groups HLA-A*11 and -A*29 had an increased frequency and HLA-A*31 and -A*30/31 were decreased. These differences were statistical significant in the whole patient group (RPP + AP).

CONCLUSIONS

Based on modern DNA techniques the present study shows an association of HLA to both RPP and AP. Certain HLA alleles seem to be associated with susceptibility or resistance to periodontitis in general. However, before this knowledge can be used for differential diagnosis or prognosis, further investigations are necessary.

Relationship between rheumatoid arthritis and periodontitis

BACKGROUND

Because of several similar features in the pathobiology of periodontitis and rheumatoid arthritis, in a previous study we proposed a possible relationship between the two diseases. Therefore, the aims of this study were to study a population of rheumatoid arthritis patients and determine the extent of their periodontal disease and correlate this with various indicators of rheumatoid arthritis.

METHODS

Sixty-five consecutive patients attending a rheumatology clinic were examined for their levels of periodontitis and rheumatoid arthritis. A control group consisted of age- and gender-matched individuals without rheumatoid arthritis. Specific measures for periodontitis included probing depths, attachment loss, bleeding scores, plaque scores, and radiographic bone loss scores. Measures of rheumatoid arthritis included tender joint analysis, swollen joint analysis, pain index, physician's global assessment on a visual analogue scale, health assessment questionnaire, levels of C-reactive protein, and erythrocyte sedimentation rate. The relationship between periodontal bone loss and rheumatological findings as well as the relationship between bone loss in the rheumatoid arthritis and control groups were analyzed.

RESULTS

No differences were noted for the plaque and bleeding indices between the control and rheumatoid arthritis groups. The rheumatoid arthritis group did, however, have more missing teeth than the control group and a higher percentage of these subjects had deeper pocketing. When the percentage of bone loss was compared with various indicators of rheumatoid arthritis disease activity, it was found that swollen joints, health assessment questionnaire scores, levels of C-reactive protein, and erythrocyte sedimentation rate were the principal parameters which could be associated with periodontal bone loss.

CONCLUSIONS

The results of this study provide further evidence of a significant association between periodontitis and rheumatoid arthritis. This association may be a reflection of a common underlying disregulation of the inflammatory response in these individuals.

Downregulation of lipopolysaccharide-induced intercellular adhesion molecule-1 expression via EP2/EP4 receptors by prostaglandin E2 in human fibroblasts

In the present study, the effect of prostaglandin E2 (PGE2) on intercellular adhesion molecule-1 (ICAM-1) expression in human gingival fibroblasts (HGF) stimulated with lipopolysaccharides (LPS) was investigated. LPS were isolated from periodontopathic bacteria, Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) and Porphyromonas gingivalis (P. gingivalis), by the phenol-water method and Escherichia coli (E. coli) LPS was used as a control. PGE2 significantly inhibited A. actinomycetemcomitans-, P. gingivalis- and E. coli-LPS-induced ICAM-1 expression. Next, of four PGE2 receptor subtypes (EP1, EP2, EP3 and EP4), we examined which subtype(s) was involved in inhibition of LPS-elicited ICAM-1 expression by PGE2. Eleven-deoxy-PGE1, a selective EP2/EP4 agonist, and butaprost, a selective EP2 agonist, attenuated A. actinomycetemcomitans-, P. gingivalis- and E. coli-LPS-elicited ICAM-1 expression, although butaprost was less potent than PGE2 and 11-deoxy-PGE1. Sulprostone, an EP1/EP3 agonist, and ONO-AP-324, an EP3 agonist, was inert to the LPS-elicited ICAM-1 expression. Furthermore, dibutyryl cAMP, a cAMP analogue, and forskolin, an adenylate cyclase activator, downregulated A. actinomycetemcomitans-, P. gingivalis- and E. coli-LPS-elicited ICAM-1 expression in HGF. Our data suggest that PGE2 downregulates A. actinomycetemcomitans- and P. gingivalis-LPS-induced ICAM-1 expression in HGF, via EP2/EP4 receptors by cAMP-dependent signaling pathways. The cAMP-elevating agents such as EP2/EP4 receptor activators may serve to control inflammatory and immune responses in periodontal disease.

Cyclooxygenase-2-dependent prostaglandin production by peripheral blood monocytes stimulated with lipopolysaccharides isolated from periodontopathogenic bacteria

BACKGROUND

Prostaglandin E2 (PGE2) plays important roles in the pathogenesis of periodontal disease. Recent studies have revealed the existence of 2 isozymes of cyclooxygenase (COX), called COX-1 and COX-2. The purpose of the present study was to investigate the contribution of COX-1 and COX-2 to PGE2 production by human peripheral blood monocytes that are stimulated with lipopolysaccharides (LPS) from periodontopathogenic bacteria.

METHODS

LPS were isolated from Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) and Porphyromonas gingivalis (P. gingivalis) by the phenol-water method. Peripheral blood monocytes were stimulated with LPS for the indicated periods, and the levels of PGE2 or interleukin (IL)-1 beta in the culture media were measured by enzyme-linked immunosorbent assay. Expression of COX-1 and -2 proteins was studied by immunocytochemical staining, and COX-2 mRNA expression was examined by Northern blot analysis.

RESULTS

Peripheral blood monocytes stimulated with A. actinomycetemcomitans- or P. gingivalis-LPS produced PGE2 in a time- and dose-dependent manner. Indomethacin, a non-selective COX-1/COX-2 inhibitor, and NS-398, a specific COX-2 inhibitor, completely inhibited PGE2 production. Immunocytochemical staining of COX-1 and COX-2 proteins showed that expression of COX-2 protein was increased in monocytes that were stimulated with A. actinomycetemcomitans- or P. gingivalis-LPS, compared with that in unstimulated monocytes, whereas expression of COX-1 protein was not altered. Northern blot analysis showed that monocytes stimulated with A. actinomycetemcomitans- or P. gingivalis-LPS expressed COX-2 mRNA, while COX-2 mRNA was not detectable in unstimulated cells. Treatment of A. actinomycetemcomitans-LPS-stimulated monocytes with NS-398 induced a significant increase of IL-1 beta production to the same extent as treatment with indomethacin.

CONCLUSIONS

These results suggest that COX-2 is induced in monocytes stimulated with LPS derived from A. actinomycetemcomitans and P. gingivalis and that the COX-2 is primarily responsible for PGE2 production. COX-2 may be pivotal in PGE2 production in periodontal lesions and may be involved in inflammatory responses.

Prostaglandin E2 is variably induced by bacterial superantigens in bovine mononuclear cells and has a regulatory role for the T cell proliferative response

Signal transduction in antigen presenting cells via MHC class II molecules induces production of prostaglandin E2 (PGE2) known to possess immunoregulatory potential. Since Staphylococcus aureus superantigens (SAgs) utilize MHC class II molecules as primary ligands, we wanted to know whether PGE2 is induced after in vitro SAg stimulation of bovine blood mononuclear cells (boMNC), and whether this arachidonic acid metabolite modulates the preferential SAg-induced proliferative response of bovine CD8+ T cells. SEB as well as SEA induced maximal amounts of PGE2 on day 2 of culture (1-2.5 x 10(-8) mol/l per 2 x 10(5) boMNC). PGE2 production could be inhibited completely by indomethacin (10(-5) mol/l) causing enhanced proliferation of boCD4+ T cells (174%) as well as of boCD8+ T cells (122%) between day 4 and 6 of the in vitro culture, however, only in a subset of the tested animals. Notably, the striking preference of proliferation of boCD8+ over boCD4+ T cells following SAg stimulation remained largely unchanged after inhibition of endogenous PGE2 synthesis or after addition of exogenous PGE2. Higher concentrations of exogenously added PGE2 (> or = 10(-8) mol/l) inhibited the proliferation reaction, mainly due to an increased death rate of both CD4+ and CD8+ blasts. In contrast, lower PGE2 concentrations between 10(-8)-10(-9) mol/l even slightly enhanced the proliferation of both T cell subsets, depending on the individual cell donor. Summing up: These data show that SAgs, indeed, can induce PGE2 production in boMNC which can enhance or reduce the proliferative response of bovine CD4+ and CD8+ T cells.

Inflammatory cytokine production and specific antibody responses to lipopolysaccharide from endodontopathic black-pigmented bacteria in patients with multilesional periapical periodontitis

We examined the induction of the cytokines interleukin (IL)-1 beta, IL-6, and IL-8 by lipopolysaccharides (LPSs) from several species of possible endodontopathic black-pigmented bacteria. Studies were conducted in human whole blood cultures from six patients (two from each group) with differing numbers of periapical periodontitis lesions (i.e. patients with radiographically clear periapical lesions in 10 or more teeth (high-lesion group, n = 4), in one or two teeth (low-lesion group, n = 6), and six healthy volunteers with no periapical lesions (no lesion group)). LPS from Prevotella intermedia ATCC 25611, Porphyromonas gingivalis 381, and Prophyromonas endodontalis ATCC 27067 induced a higher IL-8 response in the subjects of the high-lesion group, compared with the subjects of the other two groups. To ascertain the degree of sensitization by test bacteria, we examined the reactivities of antibodies in serum and saliva from the subjects to different bacterial species. LPS from P. gingivalis reacted strongly with sera from the high-lesion group. Thus, LPS from black-pigmented bacteria may be involved in multilesional periapical periodontitis by inducing particular cytokines and/or humoral immune responses.

Comparison of Nd:YAG laser versus scaling and root planing in periodontal therapy

BACKGROUND

The Nd:YAG laser has recently been used in the treatment of periodontal disease. However, although a clinical reduction of probing depth and gingival inflammation to this new approach has been reported, it has not been fully evaluated. Interleukin-1 beta (IL- 1beta), a potent stimulator of bone resorption, has been identified in gingival crevicular fluid (GCF), which is closely associated with periodontal destruction. The aim of this study was to compare the effects of Nd:YAG laser treatment versus scaling/root planing (SRP) treatment on crevicular IL-1beta levels in 52 sampled sites obtained from 8 periodontitis patients.

METHODS

One or 2 periodontitis-affected sites with a 4 to 6 mm probing depth and horizontal bone loss from 3 adjacent single-root teeth in each of 4 separate quadrants were selected from patients for clinical documentation and IL-1beta assay. Sampling site(s) from each diseased quadrant was randomly assigned to one of the following groups: 1) subgingival laser treatment (20 pps, 150 mJ) only; 2) SRP only; 3) laser treatment first, followed by SRP 6 weeks later; or 4) SRP first, followed by laser therapy 6 weeks later. The GCF was collected and the amount of IL-1beta was assayed by enzyme-linked immunosorbent assay (ELISA). Clinical parameters and GCF were measured at baseline and biweekly after therapy for 12 weeks.

RESULTS

An obvious clinical improvement (marked decrease in the number of diseased sites with gingival index > or =2) and reduction of crevicular IL- 1beta were found in all groups. The level of IL- 1beta was significantly lower in the SRP group (P = 0.035) than in the laser therapy group for the duration of the 12 weeks. The laser combined SRP therapy group showed a further reduction of IL- 1beta (6 to 12 weeks after treatment) than either laser therapy alone or SRP combined laser therapy.

CONCLUSIONS

Our data suggest that laser therapy appeared to be less effective than traditional SRP treatment. Of the 4 treatment modalities, inclusion of SRP was found to have a superior IL- 1beta response, when compared to other therapies without it. In addition, no additional benefit was found when laser treatment was used secondary to traditional SRP therapy.

Prostaglandin E2 receptors of the EP2 and EP4 subtypes downregulate tumor necrosis factor alpha-induced intercellular adhesion molecule-1 expression in human gingival fibroblasts

Prostaglandin E2 (PGE2) exerts its biological actions via EP receptors, which are divided into 4 subtypes of EP1, EP2, EP3 and EP4. In the present study, we investigated whether PGE2 regulated intercellular adhesion molecule-1 (ICAM-1) expression in human gingival fibroblasts (HGF) stimulated with tumor necrosis factor-alpha (TNF alpha) and if so, which subtype(s) of PGE2 receptors was involved. Exogenous addition of PGE2 to HGF inhibited ICAM-1 expression elicited by TNF alpha in a concentration-dependent manner. Treatment of HGF with indomethacin, a cyclo-oxygenase inhibitor, had no effect on TNF alpha-elicited ICAM-1 expression, although indomethacin completely inhibited PGE2 production enhanced by TNF alpha. Next, we examined which subtype(s) of the 4 EP receptors modulated the ICAM-1 expression elicited by TNF alpha, using subtype-specific agonists and antagonists. 11-deoxy-PGE1, a selective EP2/EP4 agonist, inhibited TNF alpha-elicited ICAM-1 expression as potently as PGE2, while butaprost, a selective EP2 agonist, was somewhat less effective than PGE2. AH23848B, an EP4 antagonist, antagonized the inhibitory effect of TNF alpha-elicited ICAM-1 expression by PGE2. Sulprostone, an EP1/EP3 agonist, and ONO-AP-324, an EP3 agonist, were inert to TNF alpha-elicited ICAM-1 expression. As EP2 and EP4 receptors are linked to elevation of intracellular cyclic AMP (cAMP), the effect of dibutyryl cAMP and 8-bromo-cAMP, cAMP analogs, on TNF alpha-elicited ICAM-1 expression was examined. Both the agents downregulated ICAM-1 expression in TNF alpha-stimulated HGF. From these data, we suggest that PGE2 downregulates TNF alpha-induced ICAM-1 expression in HGF, via EP2 and EP4 receptors by cAMP-dependent signaling pathways, which may result in control of inflammatory and immunological responses in periodontal disease.

Prostaglandin E2 downregulates interferon-gamma-induced intercellular adhesion molecule-1 expression via EP2 receptors in human gingival fibroblasts

In the present study, the effect of prostaglandin E2 (PGE2) on intercellular adhesion molecule-1 (ICAM-1) expression in interferon-gamma (IFN-gamma)-stimulated human gingival fibroblasts (HGF) was investigated. Addition of PGE2 to HGF inhibited ICAM-1 expression elicited by IFN-gamma. As PGE2 elevated intercellular cyclic AMP (cAMP) levels in HGF in a dose-dependent fashion, the effect of dibutyryl cAMP and 8-bromo-cAMP, cAMP analogues, on IFN-gamma-elicited ICAM-1 expression was examined. Both the agents downregulated ICAM-1 expression in IFN-gamma-stimulated HGF. Next, we examined which subtype(s) of the four PGE2 receptor subtypes (EP1, EP2, EP3 and EP4) modulated the ICAM-1 expression elicited by IFN-gamma, using subtype-specific agonists or antagonists. An EP2/EP4 agonist, 11-deoxy-PGE1, attenuated IFN-gamma-elicited ICAM-1 expression in a concentration-dependent manner. A specific EP4 antagonist, AH-23848B, showed no effect on inhibition of IFN-gamma-elicited ICAM-1 expression by PGE2 and 11-deoxy-PGE1. Butaprost, an EP2-selective agonist, mimicked inhibition of IFN-gamma-elicited ICAM-1 expression by 11-deoxy-PGE1. An EP3 agonist, ONO-AP-324, was inert with respect to IFN-gamma-elicited ICAM-1 expression. Sulprostone, an EP1/EP3 agonist, showed stimulatory effect on ICAM-1 expression elicited by IFN-gamma. From these results, we suggest that PGE2 downregulates IFN-gamma-induced ICAM-1 expression in HGF, primarily via EP2 receptors by cAMP-dependent signaling pathways.

Paradoxical role of PGE2 and cAMP in Actinobacillus actinomycetemcomitants strain Y4-induced lymphocyte proliferation

An immune mechanism has been suggested in the pathogenesis of periodontal disease. Actinobacillus actinomycetemcomitants (Aa) has been implicated as one of the etiological agents that induces the major immune response together with a dense infiltrate of inflammatory cells. But the exact role of these immune cells in periodontal disease has not yet been clarified. In this study the T lymphocyte (TL) proliferative response was evaluated after having being exposed to free cell supernatant (SN) from Aa. Aa SN increased TL proliferation. This mitogenic effect of Aa SN was attenuated by pretreating TL with indomethacin (INDO) or acetylsalicylic acid (ASA) but not by polymyxin B. The inhibitory effect of INDO on cell proliferation was reversed by the addition of prostaglandin E2 (PGE2) to the culture assay. Moreover, when immune cells were exposed to Aa SN they were able to generate PGE2 at the same time as intracellular levels of cAMP decreased. Both, PGE2 release and decrease accumulation of cAMP in TL were blunted by treated lymphocytes with INDO. In this paper we demonstrate that cell free SN from Aa induces a mitogenic effect on murine lymphocytes. The mechanism involves the host's immunecompetent cells and the release of PGE2 and appears not to be induced by capsular-like polysaccharide antigen. Results show a paradoxical mitogenic effect of Aa SN accompanied by increased generation of PGE2 and decreased production of cAMP by lymphocytes.

Prostaglandin E2 levels in blood plasma and in crevicular fluid of advanced periodontitis patients before and after surgical therapy

AIM

The aim of the study was to determine PGE2 levels in venous blood plasma (VBP), gingival blood plasma (GBP) and gingival crevicular fluid (GCF) in advanced periodontal patients before and after 6 months surgical treatment.

PATIENTS AND METHODS

There were 12 patients aged 28-45 years and seven healthy subjects as controls included into the study. Clinical parameters such as PLI, GI, BI, PD, AL and bone height % from radiographs were recorded before and after treatment. PGE2 levels were determined by radioimmunoassay (125 I RIA Kit, NEN(R)).

RESULTS

Before treatment the mean VBP, GBP and GCF PGE2 levels in periodontal patients were higher than healthy controls (P < 0.001, Student's t-test). Six months after treatment the mean levels of PGE2 in VBP, GBP and GCF were significantly reduced in patients with improvement of clinical and roentgenological parameters (P < 0.001, Student's t-test).

CONCLUSIONS

It can be concluded that PGE2 is involved in the pathogenesis of periodontal disease. The inflamed periodontal tissues may produce significant amount of PGE2 and the degree of inflammation might be determined by the ratios of PGE2. The lower levels of PGE2 in blood plasma and in gingival crevicular fluid after treatment are signs of improvement of periodontal disease.

The pathogenesis of periodontal diseases

This informational paper was prepared by the Research, Science, and Therapy Committee of The American Academy of Periodontology, and is intended for the information of the dental profession. The purpose of the paper is to provide an overview of current knowledge relating to the pathogenesis of periodontal diseases. The paper will review biological processes thought to provide protection against periodontal infections. It will further discuss the mechanisms thought to be responsible for both overcoming and subverting such protective mechanisms and those that lead to destruction of periodontal tissues. Since an understanding of pathogenic mechanisms of disease is one foundation upon which new diagnostic and therapeutic modalities are based, the practitioner can use this information to help make decisions regarding the appropriate application of such new modalities in patient care settings.

Inflammatory cytokine production and specific antibody responses against possible causative bacteria in patients with multilesional periapical periodontitis

We examined the induction of inflammatory cytokines (including interleukin-1, interleukin-6, interleukin-8, and tumor necrosis factor-alpha) by several species of possible causative bacteria in periapical periodontitis. Assays were done on human whole blood cultures from patients with differing numbers of periapical lesions; those having radiographically clear periapical lesions in 10 or more teeth (high lesion group), in one or two teeth (low lesion group), and healthy volunteers having no periapical lesions (no lesion group). Prevotella melaninogenica ATCC 25845 induced interleukin-6 more strongly in subjects from the high lesion group than in the other groups. To ascertain the degree of sensitization by test bacteria, we examined the reactivities of antibodies in serum and saliva from the six subjects to different bacterial species. Porphylomonas gingivalis cells reacted strongly with sera from the high lesion group. Thus, Prevotella melaninogenica and Porphylomonas gingivalis may be involved in multilesional periapical periodontitis by inducing specific cytokines and/or humoral immune responses.

Cytokine expression in periodontal health and disease

Soluble proteins that serve as mediators of cell function and are produced by various cell types, such as structural and inflammatory cells, are collectively called cytokines. Several lines of evidence have revealed that cytokines play important roles not only in tissue homeostasis but also in the pathogenesis of many infectious diseases. Recent research on biological activities in normal periodontium and the pathogenesis of periodontal diseases has clarified the involvement of various cytokines in the biological activities observed in the sites. Cytokines play crucial roles in the maintenance of tissue homeostasis, a process which requires a delicate balance between anabolic and catabolic activities. In particular, growth factors--such as fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), insulin-like growth factor (IGF), transforming growth factor-beta (TGF-beta)--are thought to play important roles in modulating the proliferation and/or migration of structural cells in the periodontium and the production of various extracellular matrices by these cells. On the other hand, there is little doubt that excessive and/or continuous production of cytokines in inflamed periodontal tissues is responsible for the progress of periodontitis and periodontal tissue destruction. Particularly, inflammatory cytokines--such as IL-1 alpha, IL-1 beta, IL-6, and IL-8--are present in the diseased periodontal tissues, and their unrestricted production seems to play a role in chronic leukocyte recruitment and tissue destruction. It is possible that monitoring cytokine production or its profile may allow us to diagnose an individual's periodontal disease status and/or susceptibility to the disease. In addition, although the hypothesis is still controversial, it has been suggested that discrete T-cell subsets (Th1 and Th2) with different cytokine profiles play specific roles in the immunopathogenesis of periodontal diseases.

Distribution of macrophage lineage cells in rat gingival tissue after topical application of lipopolysaccharide: an immunohistochemical study using monoclonal antibodies: OX6, ED1 and ED2

To discuss the role of macrophage lineage cells on the periodontal tissue destruction, we immunohistochemically examined the phenotype and the dynamics of macrophage lineage cells 1 or 3 h or 1, 2, 3 or 7 d after topical application of LPS (5 mg/ml in physiological saline) from the rat gingival sulcus using 3 monoclonal antibodies: OX6 (antigen-presenting cells), ED1 (monocytes, macrophages and dendritic cells) and ED2 (resident macrophages). We could detect at least 3 different types of macrophage lineage cells, namely OX6+/ED1+/ED2- dendritic cells and exudate macrophages and ED2+ resident macrophages. After LPS application the majority of macrophage lineage cells accumulated in the subjunctional epithelial area were newly extravasated OX6+/ED1+/ED2- dendritic cells or macrophages. The number of these cells increased progressively with time and reached a maximum level at d 2. On the other hand, number and tissue distribution of ED2+ resident macrophages did not change. These results indicate that several types of macrophage lineage cells exist in rat gingival tissue and suggest that dendritic cells and exudate macrophages transiently accumulated after LPS application are responsible for various host immune response and tissue destruction caused by LPS.

Genetic variations in cytokine expression: a risk factor for severity of adult periodontitis

Periodontitis is a collection of chronic inflammatory diseases that are caused by specific bacteria. The bacteria activate inflammatory mechanisms in the periodontal tissues that destroy collagen and bone that support the teeth. Although bacteria are essential for the initiation of periodontitis, the quantity and types of bacteria have not been sufficient to explain the differences in disease severity. In recent years, it has become evident that for many common chronic diseases, there are modifying factors that do not cause the disease but rather amplify some disease mechanisms to make the clinical condition more severe. There are now data to suggest that a few factors which amplify the inflammatory process make people susceptible to an increased severity of periodontitis. Studies of untreated disease in Sri Lanka identified 3 patterns of disease progression. Studies in twins suggested that part of the clinical characteristics of periodontitis may be explained by genetic factors, but previous attempts to identify genetic markers for periodontitis have been unsuccessful Some genetic variations (polymorphisms) are commonly found in our population and represent a mechanism by which individuals may exhibit variations within the range of what is considered biologically normal. Since certain cytokines are key regulators of the inflammatory response and are important in periodontitis, we investigated the relationship between genetic variations associated with cytokine production and periodontitis severity. There are several polymorphisms in the cluster of genes that influence IL-1 biological activity. In recent clinical trials, two of these polymorphisms, when found together, have been associated with a significant increase in the risk for severe generalized periodontitis. Genetic association with periodontitis was evident only when smokers were excluded from the analysis, confirming the importance of smoking, and suggesting that both smoking and the IL- I genotype are independent factors in severe periodontitis. It is notable that 1 polymorphism associated with severe periodontitis in our study is also known to correlate with a 2- to 4-fold increase in IL-1 beta production. These findings are consistent with the current model of how genetic factors influence common chronic diseases. If we apply this model to periodontitis, it would involve the following: 1) a disease-initiating factor that would undoubtedly be specific bacteria such as Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans. and Bacteroides forsythus: and 2) modifiers of disease mechanisms that account for the clinical severity, including smoking, the IL-I genotype, certain systemic diseases, and psychosocial stress. The association of the IL-I genotype with severe periodontitis is consistent with several lines of periodontal research. Several studies have suggested there is a substantial genetic influence in periodontal disease. Although specific genetic markers have been identified in the uncommon juvenile forms of periodontitis, previous studies of specific genetic markers in adults with periodontitis have not been encouraging. Many investigators have, however, demonstrated a role for IL-1 in the initiation and progression of periodontitis. For example, IL-1 activates the degradation of the extracellular matrix and bone of the periodontal tissues, and elevated tissue or gingival fluid levels of IL-1 beta have been repeatedly associated with periodontitis. In addition, IL-1 is a strong enhancer of tissue levels of PGE2 and TNF-alpha. The association of severe periodontitis with smoking and the IL-1 genotype suggest a role for these factors in the pathogenesis of periodontitis. The finding that host modifying factors are associated with severe periodontitis suggest a biological mechanism by which some individuals, if challenged by bacterial accumulations, may have a more vigorous immunoinflammatory response, leading to more severe clinical disease. (ABSTRACT

Inflammatory mediators of the terminal dentition in adult and early onset periodontitis

Based upon the prosthodontic literature, subjects who are at the transition stage between natural dentition and edentulism are called "terminal dentition" (TD) cases. The aim of the present cross-sectional investigation was to characterize the local and systemic inflammatory responses in 2 groups of patients with terminal dentition periodontitis. Eight severe adult periodontitis terminal dentition (AP-TD) subjects and 8 early onset periodontitis terminal dentition (EOP-TD) subjects were entered into the study. Our purpose was to measure an extended battery of cytokines in the gingival crevicular fluid (GCF) and in lipopolysaccharide (LPS)-stimulated monocytic culture supernatants as well as gingival mononuclear cell messenger RNA (mRNA) transcripts determined from biopsy samples. Within the GCF there were 3 tiers (levels) of mediators based upon approximate 10-fold differences in concentration. The highest tier included prostaglandin E2 (PGE2), interleukin-1 beta (IL-1 beta) and interleukin-2 (IL-2), the intermediate tier included tumor necrosis factor alpha (TNF alpha) and interferon gamma (IFN-gamma) and at the lowest concentration level were interleukin-4 (IL-4) and interleukin-6 (IL-6). Thus, the GCF analysis clearly indicated that in both AP-TD and EOP-TD groups the monocytic, i.e. IL-1 beta and PGE2 and Th1, i.e. IL-2 and IFN-gamma, inflammatory mediator levels quantitatively dominated over the Th2 mediators, i.e. IL-4 and IL-6. LPS-stimulated monocytic release of IL-1 beta, PGE2 and TNF alpha was significantly elevated in both AP-TD and EOP-TD groups compared to those of a control group of 21 subjects with moderate to advanced adult periodontitis. The cytokine mRNA expression of isolated gingival mononuclear cells showed that in both the AP-TD and the EOP-TD groups Th1 and Th2 cytokines were expressed, with low levels of IL-4 and IL-12. In conclusion, our data suggest that this cross-sectional TD periodontitis model may reflect progressive periodontal disease associated with tooth loss. Furthermore, although Th1 cytokine levels in the GCF dominate over the Th2 response, monocytic activation provides the main source of proinflammatory mediators. In addition, LPS-stimulated peripheral blood monocytes demonstrate an upregulated inflammatory mediator secretion in the terminal dentition.

Periodontitis and concentrations of the cellular immune activation marker neopterin in saliva and urine

Neopterin concentrations in diverse body fluids provide a well established indication for activation of the cell-mediated immune system. Neopterin concentrations were measured in the saliva and urine of 29 patients with varying numbers of teeth affected by periodontitis. While neopterin concentrations in urine increased slightly but not significantly in parallel with increasing numbers of affected teeth, salivary neopterin levels showed a significant and positive correlation with number of diseased teeth (linear correlation coefficient = 0.48, P = 0.012). Additionally, when the patients were grouped according to the median number of affected teeth (20), salivary specimens of subjects with one to 20 affected teeth showed significantly lower neopterin concentrations than specimens from those with more than 20 diseased teeth (P = 0.0045, Student's t-test). In contrast, urinary neopterin concentrations did not differ significantly among these two groups. This pilot study suggests that salivary neopterin concentrations may reflect local immune activation even in situations where no systemic activation can be detected.