Lipopolysaccharide from Actinobacillus actinomycetemcomitans stimulates production of interleukin-1beta, tumor necrosis factor-alpha, interleukin-6 and interleukin-1 receptor antagonist in human whole blood

Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans) is supposed to be an important etiological agent in localized juvenile periodontitis (LJP). We have studied the effect of lipopolysaccharide (LPS) extracted from these periodontopathogenic bacteria on synthesis of the proinflammatory cytokines, interleukin-1beta(IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and the anti-inflammatory cytokine IL-1 receptor antagonist (IL-1ra) in human whole blood. LPS from A. actinomycetemcomitans in concentrations > or =1 ng/ml induced a significant production of all these proinflammatory cytokines, whereas LPS from Escherichia coli (E. coli), strain 026:B6 had to be added in concentrations > or =1 microg/ml to obtain a similar effect. Similarly, LPS from A. actinomycetemcomitans > or =0.1 ng/ml resulted in production of IL-1ra, while LPS from E. coli 026:B6 had to be added at > or =10 ng/ml to obtain similar effects. It has been suggested that the ratio between production of proinflammatory and anti-inflammatory cytokines may influence the outcome of periodontal diseases. Other in vitro and in vivo studies have, however, indicated that very large excesses (100-1000 times) of IL-1ra compared to IL-1beta are required to shift the IL-1ra:IL-1beta ratio in favor of an inhibition of IL-1 bioactivity. In our ex vivo system, we found that stimulation with extremely low doses of A. actinomycetemcomitans LPS (0.1-1 ng/ml) resulted in IL-1ra production solely, without concomitant production of IL-1beta, the excess of IL-1ra over IL-1beta peaking at 1 ng/ml, which accordingly should suggest that LPS from A. actinomycetemcomitans primarily has proinflammatory effects.     

The release of interleukin-1β, tumor necrosis factor-α and i nterferon-γ by cultured peripheral blood mononuclear cells from patient swith periodontitis

The extracellular release of IL-1 beta by cultured peripheral blood monocytes from 26 periodontitis patients and 26 control subjects was measured by radioimmunoassay. Unstimulated monocytes from periodontitis patients released significantly more IL-1 beta than controls during 24 h of culture; there was a wide variation in the amount of IL-1 beta released (0.45-13.00 ng/ml per 10(6) cells) which did not correlate with either the degree of bone loss or pocket formation observed clinically. When stimulated with lipopolysaccharide (LPS; Actinobacillus actinomycetemcomitans; 5 micrograms/ml) monocytes from periodontitis patients produced significantly more IL-1 beta than those from control subjects. Monocyte culture supernatants from another 10 periodontitis patients and 10 control subjects were also assayed for both IL-1 beta and TNF-alpha by enzyme-linked immunosorbent assays. Spontaneous and LPS-stimulated (Bacteroides gingivalis; 5 micrograms/ml) IL-1 beta release were again significantly higher for periodontitis patients. TNF-alpha was detected in the periodontitis cultures (0-765 pg/ml per 10(6) cells), but the mean value was not significantly different from controls. LPS-stimulated TNF-alpha release, however, was significantly higher than for control subjects, and there was a strong correlation between spontaneous IL-1 beta and TNF-alpha release by monocytes from the periodontitis group. Measurement of interferon-gamma (IFN-gamma) in lymphocyte cultures from these patients by immunoradiometric assay showed that IFN-gamma levels in periodontitis cultures were consistently low, but not significantly so when compared to controls; both groups responded equally to concanavalin-A (5 micrograms/ml). Although the precise roles of IL-1 beta and TNF-alpha in periodontitis remain unclear, these data provide evidence that both cytokines may participate in the pathogenesis of the disease.     

Doxycycline reduces lipopolysaccharide-induced inflammatory mediator secretion in macrophage and ex vivo human whole blood models

Background: Tetracyclines have been extensively used as adjuncts in the treatment of some forms of periodontitis. The aim of this study was to evaluate the capacity of doxycycline to influence the secretion of inflammatory mediators in macrophage and ex vivo human whole blood models stimulated with periodontopathogen lipopolysaccharides (LPS). Methods: Monocyte-derived macrophages were treated with various concentrations of doxycycline prior to being stimulated with Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) LPS. The capacity of doxycycline to mediate the inflammatory response was also tested in an ex vivo whole blood model (whole blood isolated from periodontitis patients and healthy subjects) stimulated with Porphyromonas gingivalis LPS. The secretion of interleukin (IL)-1beta, -6, and -8 and tumor necrosis factor-alpha (TNF-alpha) in both models was assessed by enzyme-linked immunosorbent assays (ELISA). Changes in phosphorylation state of kinases induced by A. actinomycetemcomitans LPS and doxycycline in the macrophage model were characterized by a multiplex ELISA analysis. Results: The secretion of IL-1beta and -8 and TNF-alpha by macrophages decreased significantly (P <0.05) when they were pretreated with 2 muM doxycycline, whereas a concentration of 10 muM was required to significantly reduce IL-6 secretion. Pretreatment of macrophages with 10 muM doxycycline prior to A. actinomycetemcomitans LPS stimulation resulted in a marked decrease in the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 (-76%). In the whole blood model, doxycycline, more particularly at 10 muM, was also a potent inhibitor of the proinflammatory cytokine response. Conclusion: These two models provided clear evidence that some of the clinically proven benefits of doxycycline may be related to its ability to regulate inflammatory mediator release by host cells.     

Association between periodontitis and hyperlipidemia: cause or effect?

BACKGROUND: Epidemiological studies suggest a relationship between periodontitis and coronary artery disease, but the mechanism has not been established. Recent studies in animals indicate that low dose endotoxin, as in a gram-negative infection, can induce hyperlipidemia and myeloid cell hyperactivity. The association between periodontitis, systemic exposure to Porphyromonas gingivalis, lipopolysaccharides (LPS), and hyperlipidemia has not been examined in humans. METHODS: Sera were obtained from 26 adult periodontitis patients and 25 healthy control (C) subjects selected from patients and staff. Serum antibodies against Porphyromonas gingivalis and its LPS were analyzed by enzyme-linked immunosorbent assay (ELISA) and Western blotting, respectively. Serum triglycerides (TG) and cholesterol (CHOL) were assayed by a commercial laboratory. The associations between AP and blood levels of TG, CHOL, and anti-P. gingivalis whole cells and LPS were examined by logistic regression analysis. Peripheral blood polymorphonuclear leukocytes (PMNs) from 6 healthy fasted donors were incubated with purified TG (0.1 mg/ml) for 2 hours at 37 degrees C, stimulated with 100 ng/ml P. gingivalis LPS, and the release of IL-1beta measured by ELISA. RESULTS: The presence of periodontitis was significantly associated with age (odds ratio = 3.5, P = 0.04), elevated TG levels (odds ratio = 8.6, P = 0.0009), elevated CHOL levels (odds ratio = 7, P = 0.004), elevated ELISA titer (odds ratio = 35, P = 0.003) and reactivity with P. gingivalis LPS (odds ratio = 41, P = 0.001). PMNs from all 6 healthy patients released modest levels of IL-1beta (10 to 60 pg/ml) when stimulated with 100 ng/ml P. gingivalis LPS. Addition of TG resulted in a significant increase (P <0.05) in IL- 1beta secreted that ranged from 7 to 150% over LPS alone. No IL-1beta was elicited by TG or vehicle alone. CONCLUSIONS: The results of this study indicate the presence of a significant relationship between periodontitis, hyperlipidemia, and serum antibodies against P. gingivalis LPS that warrants further examination in a larger patient population. Furthermore, these studies indicate that elevated triglycerides are able to modulate IL-1beta production by PMNs stimulated with P. gingivalis LPS.     

Lipopolysaccharide from Actinobacillus actinomycetemcomitans stimulates macrophages to produce interleukin-1 and tumor necrosis factor mRNA and protein

Actinobacillus actinomycetemcomitans is associated with periodontal disease in children and adults. We report that low concentrations of lipopolysaccharide (LPS) from A. actinomycetemcomitans stimulated human macrophages to increase dramatically their accumulation of mRNA coding for interleukin-1 alpha (IL-1 alpha), IL-1 beta as well as tumor necrosis factor (TNF). Protein levels of IL-1 and TNF alpha also increased. Levels of these mRNAs increased by 4-5 fold as compared with unstimulated macrophages when these cells were cultured with as little as 2 ng/ml LPS from A. actinomycetemcomitans. Polymyxin binds and blocks the action of LPS; polymyxin inhibited the ability of LPS from A. actinomycetemcomitans to increase levels of IL-1 beta mRNA. The LPS of A. actinomycetemcomitans stimulated increased levels of IL-1 beta mRNA in the presence of cycloheximide, showing that stimulation by this LPS did not require new synthesis of protein. Furthermore, dexamethasone inhibited the ability of LPS from A. actinomycetemcomitans to stimulate the accumulation of mRNA coding for IL-1 beta. A. actinomycetemcomitans is an invasive microorganism of the gingiva; high intragingival numbers correlate with sites undergoing local destruction of the periodontium. IL-1 alpha, IL-1 beta, and TNF are potent monokines that mediate inflammation and resorption of bone. Out studies suggest that macrophages migrating to these gingival sites of A. actinomycetemcomitans infection will be stimulated by LPS of A. actinomycetemcomitans to produce IL-1 alpha, IL-1 beta and TNF. These cytokines will mediate gingival inflammation and stimulate resorption of alveolar bone.     

Nitric oxide production by a murine macrophage cell line (RAW264.7) stimulated with lipopolysaccharide from Actinobacillus actinomycetemcomitans

The aim of this study was to determine whether Actinobacillus actinomycetemcomitans lipopolysaccharide (LPS-A. actinomycetemcomitans) could stimulate a murine macrophage cell line (RAW264.7 cells) to produce nitric oxide (NO). The cells were treated with LPS-A. actinomycetemcomitans or Escherichia coli LPS (LPS-Ec) for 24 h. The effects of N(G)-monomethyl-L-arginine (NMMA), polymyxin B and cytokines (IFN-gamma, TNF-alpha, IL-4 and IL-12) on the production of NO were also determined. The role of protein tyrosine kinase, protein kinase C and microtubulin organization on NO production were assessed by incubating RAW264.7 cells with genistein, bisindolylmaleide and colchicine prior to LPS-A. actinomycetemcomitans stimulation, respectively. NO levels from the culture supernatants were determined by the Griess reaction. The results showed that LPS-A. actinomycetemcomitans stimulated NO production by RAW264.7 cells in a dose-dependent manner, but was slightly less potent than LPS-Ec. NMMA and polymyxin B blocked the production of NO. IFN-gamma and IL-12 potentiated but IL-4 depressed NO production by LPS-A. actinomycetemcomitans-stimulated RAW264.7 cells. TNF-alpha had no effects on NO production. Genistein and bisindolylmalemaide, but not colchicine, reduced the production of NO in a dose-dependent mechanism. The results of the present study suggest that A. actinomycetemcomitans LPS, via the activation of protein tyrosine kinase and protein kinase C and the regulatory control of cytokines, stimulates NO production by murine macrophages.     

Anti-inflammatory activity of a high-molecular-weight cranberry fraction on macrophages stimulated by lipopolysaccharides from periodontopathogens

Periodontitis is a chronic inflammatory disease affecting oral tissues. The continuous, high production of cytokines by host cells triggered by periodontopathogens is thought to be responsible for the destruction of tooth-supporting tissues. Macrophages play a critical role in this host inflammatory response to periodontopathogens. The aim of this study was to investigate the effect of non-dialyzable material prepared from cranberry juice concentrate on the pro-inflammatory cytokine response of macrophages induced by lipopolysaccharides (LPS) from Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum subsp. nucleatum, Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Escherichia coli. Interleukin-1 beta (IL-1beta), IL-6, IL-8, tumor necrosis factor alpha (TNF-alpha), and Regulated on Activation Normal T-cell Expressed and Secreted (RANTES) production by macrophages treated with the cranberry fraction prior to stimulation by LPS was evaluated by ELISA. Our results clearly indicate that the cranberry fraction was a potent inhibitor of the pro-inflammatory cytokine and chemokine responses induced by LPS. This suggests that cranberry constituents may offer perspectives for the development of a new therapeutic approach to the prevention and treatment of periodontitis.     

Capsular polysaccharide from Actinobacillus actinomycetemcomitans inhibits IL-6 and IL-8 production in human gingival fibroblast

We previously reported that a capsular polysaccharide (CP) from Actinobacillus actinomycetemcomitans Y4 induces bone resorption in a mouse organ culture system and osteoclast formation in mouse bone marrow cultures. However, the effects of A. actinomycetemcomitans Y4 CP on human gingival fibroblasts (HGF) are still unclear. The present study was undertaken to test the hypothesis that A. actinomycetemcomitans Y4 CP alters the production of inflammatory cytokines, such as interleukin-6 (IL-6) and IL-8 by HGF. When HGF were cultured with various concentrations of Y4 CP for 24 h, IL-6 and IL-8 production decreased in a concentration-dependent manner. Y4 CP (100 microg/ml) suppressed the release of IL-6 from 9.09 +/- 0.08 ng/ml to 0.34 +/- 0.21 ng/ml (P < 0.01) and IL-8 production decreased from 3.76 +/- 0.03 ng/ml to 0.09 +/- 0.01 ng/ml (P < 0.01). Y4 CP suppressed 70-80% of the release of IL-6 and IL-8 from HGF stimulated with Y4 lipopolysaccharide (LPS), too. Interestingly, anti-A. actinomycetemcomitans Y4 CP completely inhibited the effect of A. actinomycetemcomitans Y4 CP on IL-6 and IL-8 production from HGF. These results indicate that Y4 CP inhibits the release of IL-6 and IL-8 from HGF, suggesting that A. actinomycetemcomitans Y4 modulates the inflammatory response in periodontitis. Remarkably, this inhibitory effect was reversed by specific anti-A. actinomycetemcomitans Y4 CP suggesting an important relationship between the organism and the humoral host response.     

Suppression of lipopolysaccharide-induced cytokine production of gingival fibroblasts by a soybean, Kunitz trypsin inhibitor

BACKGROUND: Human bikunin, a Kunitz-type trypsin inhibitor, inhibits inflammation by down-regulating the expression of proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha) in tumor cells and inflammatory cells. OBJECTIVES: We analyzed the effect of a soybean-derived Kunitz trypsin inhibitor (KTI) on TNF-alpha production in human gingival fibroblasts stimulated by lipopolysaccharide (LPS), an inflammatory inducer. MATERIAL AND METHODS: Mitogen-activated protein kinase (MAPK) activation and cytokine levels were monitored using western blot and a specific enzyme-linked immunosorbent assay (ELISA). RESULTS: Here, we show (i) a soybean KTI abrogates LPS-induced up-regulation of TNF-alpha mRNA and protein expression in a dose-dependent manner in gingival fibroblasts, (ii) KTI also blocks the induction of TNF-alpha target molecules interleukin-1beta (IL-1beta) and IL-6 proteins, (iii) inhibition by KTI of TNF-alpha induction correlates with the suppressive capacity of extracellular signal-regulated kinase 1/2 (ERK1/2) and p38 signaling pathways, implicating repressed ERK1/2 and p38 signalings in the inhibition, and (iv) pretreatment of cells with KTI blocked LPS-induced nuclear factor kappaB (NFkappaB) activation. CONCLUSION: Our results indicate that KTI inhibits LPS-induced up-regulation of cytokine expression possibly through suppression of ERK1/2 and p38 kinase-mediated NFkappaB activation. These findings may identify anti-inflammatory properties of KTI at the level of gingival fibroblasts and may be relevant to the use of KTI in modulating inflammation, including periodontal disease.     

Influence of proinflammatory cytokines on Actinobacillus actinomycetemcomitans specific IgG responses

OBJECTIVE: High levels of serum anti-Actinobacillus actinomycetemcomitans immunoglobulin G (IgG) correlate with reduced extent and severity of periodontal disease and the present study was undertaken to begin testing the hypothesis that proinflammatory cytokines are important in the induction of optimal anti-A. actinomycetemcomitans IgG responses. BACKGROUND: Studies with pokeweed mitogen indicate that interleukin-1alpha (IL-1alpha) and IL-1beta are necessary for optimal IgG1 and IgG2 production and that prostaglandin E(2) (PGE(2)) and interferon-gamma (IFN-gamma) selectively promote IgG2, which is a major component of the anti-A. actinomycetemcomitans response in vivo. The pokeweed mitogen results suggest that these proinflammatory cytokines would also be necessary for optimal production of IgG specific for A. actinomycetemcomitans. METHODS: Peripheral blood mononuclear cells from A. actinomycetemcomitans-seropositive subjects with localized aggressive periodontitis were stimulated with A. actinomycetemcomitans in immune complexes capable of binding follicular dendritic cells that participate in the induction of recall responses in vivo. Cultures were manipulated with anti-IL-1alpha, anti-IL-1beta, anti-IFN-gamma, anti-IL-12, anti-CD21, indomethacin, and PGE(2). Actinobacillus actinomycetemcomitans specific IgG production was monitored by enzyme-linked immunosorbent assay (ELISA). RESULTS: Addition of follicular dendritic cells to peripheral blood mononuclear cells cultures resulted in follicular dendritic cell-lymphocyte clusters and increased anti-A. actinomycetemcomitans IgG responses (3-40-fold increases) compared with controls lacking follicular dendritic cells. Anti-IL-1alpha, anti-IL-1beta, anti-IFN-gamma, anti-IL-12, anti-CD21 and indomethacin suppressed anti-A. actinomycetemcomitans IgG production by half or more. PGE(2) restored IgG responses suppressed by indomethacin. CONCLUSIONS: The cytokines IL-1alpha, IL-1beta, IFN-gamma, IL-12, and PGE(2) were all necessary for optimal production of human anti-A. actinomycetemcomitans and the need for proinflammatory cytokines including the T helper 1 (Th1) cytokines is consistent with a response with a significant IgG2 component.     

Osteoclastogenesis inhibitory factor/osteoprotegerin in synovial fluid from patients with temporomandibular disorders

The goal of this study was to measure the activities of osteoclastogenesis inhibitory factor/osteoprotegerin (OCIF/OPG), interleukin-1beta (IL-1beta), and tumour necrosis factor-alpha (TNF-alpha) in synovial fluid from 24 patients with internal derangement and 26 with osteoarthritis of the temporomandibular joint (TMJ). Five asymptomatic healthy volunteers were studied as control. Concentrations of OCIF/OPG, IL-1beta, and TNF-alpha were determined by enzyme-linked immunosorbent assay. The mean OCIF/OPG concentration in the patients with osteoarthritis (71 pg/ml) was significantly lower than those in the patients with internal derangement (160 pg/ml, P< 0.05) and the healthy volunteers (196 pg/ml, P< 0.01). In contrast, the IL-1beta and TNF-alpha concentrations were similar in all three groups. These results suggest that OCIF/OPG is associated with the pathogenesis of osteoarthritis of the TMJ. Perhaps, decreased OCIF/OPG concentrations promote osteoclastic activity and induce osteoarthritis of the TMJ.     

Bone resorption and local interleukin-1alpha and interleukin-1beta synthesis induced by Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis lipopolysaccharide

Different types of periodontopathic bacterial lipopolysaccharide (LPS) exert various biological activities in vitro. However, whether or not these activities also occur in vivo remains unclear. Thus the present study investigates bone resorption, as well as local IL-1alpha and IL-1beta synthesis induced by Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis LPS in the periodontal tissue of mice. Both types of LPS were injected into mouse gingiva every 48 h and the animals were sacrificed 6 h after the 1st. 4th, 7th, 10th, 13th, 16th, 20th, or 24th injection. Bone resorption in the injected gingiva was histopathologically and histomorphometrically investigated and local concentrations of IL-1alpha and IL-1beta were detected using an enzyme-linked immunosorbent assay. The active resorption ratio was significantly higher in the group given the 10th injection of LPS from A. actinomycetemcomitans than in the group given P. gingivalis LPS. Furthermore, A. actinomycetemcomitans LPS stimulated significantly more synthesis of IL-1alpha than P. gingivalis LPS after the 4th and 10th injections. and of IL-1beta after the 4th, 7th, 10th, 13th, 16th and 20th injections. These results suggest that A. actinomycetemcomitans LPS is a more potent inducer of bone resorption and synthesis of IL-1alpha and IL-1beta in the short term than P. gingivalis LPS.     

Hemoglobin and LPS act in synergy to amplify the inflammatory response

Vascular disruption and bleeding during periodontitis likely increase the levels of hemoglobin in gingival crevicular fluid. The aim of this study was to investigate the effect of hemoglobin on the inflammatory responses of human macrophages stimulated with lipopolysaccharides (LPS) isolated from periodontopathogens. The production of interleukin-1 beta (IL-1beta), IL-6, IL-8, and tumor necrosis factor alpha (TNF-alpha) by macrophages following challenges with Porphyromonas gingivalis and Fusobacterium nucleatum LPS in the presence or absence of human hemoglobin was analyzed by ELISA. The effect of hemoglobin on LPS-binding to macrophages was evaluated with (3)H-LPS. Hemoglobin and LPS from periodontopathogens acted in synergy to stimulate the production of high levels of IL-1beta, IL-6, IL-8, and TNF-alpha by macrophages. Hemoglobin also enhanced LPS-binding to macrophages. This study suggests that hemoglobin contributes to increases in the levels of pro-inflammatory mediators in periodontal sites by acting in synergy with LPS from periodontopathogens, thus favoring the progression of periodontitis.     

Effect of lipopolysaccharide from Porphyromonas gingivalis on prostaglandin E2 and interleukin-1β release from rat periosteal and human gingival fibroblasts in vitro

Lipopolysaccharide (LPS) was extracted from Porphyromonas gingivalis (W83) by the Westphal procedure, nuclease-digested and ultracentrifuged. Fibroblasts were obtained from human gingival tissue and rat periosteum, grown to confluence then stimulated in serum-free medium with 0.1, 1.0 and 10.0 micrograms/ml LPS. The levels of prostaglandin E2 (PGE2) and interleukin-1 beta (IL-1 beta) released were measured after 2, 4 and 6 d by specific radioimmunoassays. Unstimulated gingival fibroblasts produced low levels of PGE2 (24.5 +/- 1.5 (SD) ng/ml) and IL-1 beta (0.34 +/- 0.29 ng/ml). LPS stimulated statistically significant dose-related increases in PGE2 and IL-1 beta at the concentrations of LPS tested. At 10.0 micrograms/ml, LPS-stimulated fibroblasts produced 363.5 +/- 40.3 ng/ml PGE2 and 1.81 +/- 0.1 ng/ml IL-1 beta in 6 d. These results demonstrate that LPS from P. gingivalis is capable of stimulating PGE2 and IL-1 beta release from fibroblasts. This would appear to be an additional mechanism by which LPS can induce tissue breakdown in periodontal disease.     

LPS-elicited secretory responses in monocytes: Altered release of PGE2 but not IL-1/β in patients with adult periodontitis

Lipopolysaccharide responsiveness in human subjects was assessed through the examination of LPS-stimulated PGE2 and IL-1 beta release from counterflow isolated monocytes from patients with varying levels of periodontal destruction. This study was performed in order to investigate a possible relationship between LPS-mediated secretory responses in monocytes and susceptibility to periodontal destruction in humans. Subjects were chosen based on apparent resistance or susceptibility to disease as measured by little or no periodontal destruction versus generalized severe destruction, respectively. Because IFN-gamma can influence LPS-stimulated responses, the effect of IFN-gamma on the LPS-stimulated release of PGE2 and IL-1 beta was also assessed. Peripheral blood monocytes were separated by counterflow centrifugation and cultured (10(6)/ml/well) with control medium or medium containing LPS from Bacteroides gingivalis, B. intermedius, Actinobacillus actinomycetemcomitans, or Salmonella typhimurium, with or without 10 Units/ml recombinant IFN-gamma. Media were exchanged at 24 and 48 hours and culture supernatants assayed for both PGE2 and IL-1 beta by RIA. Patients classified as Susceptible to periodontitis demonstrated 2- to 3-fold greater PGE2 release than Resistant patients. This difference was observed with all LPS preparations over both the 0-24 hour and 24-48 h culture periods. IL-1 beta release, however, was not significantly different between patient groups. IFN-gamma did not affect the LPS-stimulated release of PGE2 but significantly enhanced the release of IL-1 beta. The IFN-gamma effects were similar for both patient groups. These findings indicate that LPS-stimulated PGE2 release from peripheral blood monocytes may correlate with susceptibility to periodontitis in human subjects.     

Inducing effect of periodontopathic bacteria on interleukin-1 production by mouse peritoneal macrophages

Sonicated extracts from Bacteroides gingivalis. Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans , and Actinomyces viscosus were found to strongly induce IL-1 production by mouse peritoneal macrophages as early as 24 h after addition of the sonicates. A significant increase in the IL-1 production was observed at a dose of 1 μg/ml (dry weight) of the sonicates. The inducing ability was equivalent to 1 μg/ml Escherichia coli lipopolysaccharide. The highest production of IL-1 was observed in the macrophages treated with A. actinomycetemcomitans. Sonicated extracts of both gram-negative and gram-positive bacteria were able to induce the IL-1 production by macrophages from C3H/HeJ mice, which are LPS low-responders. These results suggest that periodontopathic bacteria induce IL-1 production by macrophages. IL-1 may play an important role in development of periodontal disease.     

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.