Human monocyte response to cementum extracts from periodontally diseased teeth: effect of conditioning with tetracycline

Effect of a controlled release device containing minocycline microspheres on the treatment of chronic periodontitis: A comparative study

INTRODUCTION

Adjunctive therapy with locally delivered antimicrobials has resulted in improved clinical outcomes. The aim of this study was to evaluate the efficacy and safety of locally administered minocycline microspheres (Arestin) in the treatment of chronic periodontitis.

MATERIALS AND METHODS

A total of 60 sites from 15 patients in the age group of 35-50 years, who had periodontal pockets measuring 5-8 mm and had been diagnosed with chronic periodontitis, were selected for the study. The selected groups were randomly assigned to either the control group (group A) or the treatment/test group (group B). Only scaling and root planing were done at the base line visit for the control sites followed by local application of Arestin (1 mg). Clinical parameters such as plaque index, gingival index, and gingival bleeding index were recorded at baseline, day 30, day 90, and day 180 in the selected sites of both the groups. Probing pocket depth also was recorded at baseline, day 90, and day 180 for both the groups.

RESULTS

A statistically significant reduction was observed in both groups. Group B showed better results than Group A and these differences were statistically significant.

CONCLUSION

The results of this study clearly indicate that treatment with scaling and root planing plus minocycline microspheres (Arestin) is more effective and safer than scaling and root planing alone in reducing the signs of chronic periodontitis.

Tetracycline Conditioning Augments the In Vivo Inflammatory Response Induced by Cementum Extracts

BACKGROUND

Studies have shown that extracts of cementum from periodontally involved teeth stimulated cytokine secretion from cultured human monocytes and that this stimulatory effect is inhibited by conditioning of the cementum with tetracycline. Using the subcutaneous chamber model in mice, the present study was designed to test the ability of cementum extracts from periodontally diseased teeth to induce an inflammatory response in vivo and to evaluate the effect of cementum conditioning with tetracycline.

METHODS

Subcutaneous chambers were implanted in 24 mice. Two weeks later, the animals received intrachamber injection of one of the following: diseased-cementum extract, healthy-cementum extract, diseased-cementum extract preconditioned with tetracycline, or medium alone. Chamber exudates were harvested and analyzed for leukocyte levels, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, and interleukin-10 (IL-10).

RESULTS

Injection of healthy- or diseased-cementum extracts increased the intrachamber levels of leukocytes. Extracts of diseased cementum were found to significantly increase the levels of TNF-alpha, IFN-gamma, and IL-10, compared with extracts of healthy cementum or media alone. Peak cytokine levels were observed 2 hours postinjection. Conditioning of diseased cementum with tetracycline before extraction resulted in augmented levels of TNF-alpha and IFN-gamma, and reduced levels of IL-10, compared with untreated diseased cementum.

CONCLUSIONS

The present results demonstrate that conditioning of diseased cementum with tetracycline may induce an intense inflammatory response in a mouse model, and they suggest that local application of tetracycline for root conditioning should be carefully reinvestigated.

In vitro effect of laser irradiation on cementum-bound endotoxin isolated from periodontally diseased roots

BACKGROUND

In a previous study, we evaluated the in vivo effects of an Nd:YAG laser on periodontal disease by measuring crevicular interleukin (IL)-1beta levels before and after laser application. It was found that laser therapy was less effective than traditional scaling and root planing. These results might be due to incomplete removal of microbial residues and cementum-bound endotoxin on root surfaces by the laser. In this study, we explored the in vitro effectiveness of an Nd:YAG laser for the elimination of cementum-bound endotoxin by measuring IL-1beta changes in stimulated monocytes.

METHODS

Fresh human monocytes were harvested from adults without periodontitis and grown in RPMI 1640 medium. Diseased cementum particles were collected and prepared from teeth with untreated periodontitis and were irradiated with 5 levels of laser energy. Cementum particles were subjected to endotoxin testing by a limulus amebocyte lysate (LAL) assay and then were incubated with cultured monocytes. Production of IL-1beta in stimulated monocytes was measured by enzyme-linked immunosorbent assay and quantified by spectrophotometry.

RESULTS

The endotoxin unit (EU) of diseased cementum was 18.4 EU/mg, which seemed to be remarkably lower than that of common periodontal pathogens including Porphyromonas gingivalis (381) at 15,300 EU/mg/ml, Prevotella intermedia (ATCC 25611) at 227 EU/mg/ml, and Fusobacterium nucleatum (ATCC 25586) at 1,987 EU/mg/ml. Monocytes subjected to stimulation by diseased cementum particles without laser irradiation produced 124 to 145 pg/ml IL-1beta, 9- to 18-fold higher than that of unstimulated monocytes (7.07 to 15.95 pg/ml). Diseased cementum particles after irradiation with various energy levels of the Nd:YAG laser could still stimulate monocytes to secrete 89 to 129 pg/ml IL-1beta. No statistically significant difference was found in the production of IL-1beta induced by diseased-bound cementum with or without laser irradiation.

CONCLUSIONS

The Nd:YAG laser varying from 50 mJ, 10 pps to 150 mJ, 20 pps, for 2 minutes, did not seem to be effective in destroying diseased cementum endotoxin.

Inhibition of matrix metalloproteinase-mediated periodontal bone loss in rats: a comparison of 6 chemically modified tetracyclines

BACKGROUND

Chemically modified tetracyclines (CMTs), devoid of antimicrobial activity, inhibit pathologically elevated collagenase activity both in vivo and in vitro. In the current study, doxycycline and 5 different CMTs were tested to prevent matrix metalloproteinase (MMP)-dependent periodontal tissue breakdown in an animal model of periodontitis.

METHODS

Adult male rats received intragingival injections with either 10 microl of physiologic saline or Escherichia coli endotoxin (1 mg/ml) every other day for 6 days and were distributed into 8 treatment groups (12 rats/group): saline (S), endotoxin alone (E), E + CMT-1, E + CMT-3, E + CMT-4, E + CMT-7, E + CMT-8, and doxycycline. All animals were treated daily with 1 ml of 2% carboxymethyl cellulose (CMC) alone or containing one of the above-mentioned CMTs (2 mg/day) orally. The gingival tissues were removed, extracted, and assayed for gelatinase (GLSE). Some rat maxillary jaws from each treatment group were fixed in buffered formalin and processed for histology and immunohistochemistry for the cytokines tumor necrosis factor (TNF), interleukin (IL)-1, and IL-6, and MMP-2 and MMP-9.

RESULTS

Endotoxin injection induced elevated GLSE activity (functional assay and osteoclast-mediated bone resorption), the former identified as predominantly MMP-9 (92 kDa GLSE) by gelatin zymography. All 6 tetracyclines (2 mg/day) inhibited periodontal breakdown in the following order of efficacy: CMT-8 > CMT- 1 > CMT-3 > doxycycline > CMT-4 > CMT-7. Immunohistochemistry was positive for TNF, IL-1, and IL-6 in the inflammatory cells from untreated endotoxin rat tissues, whereas treatment with CMTs decreased the number of immuno-positive stained cells for cytokines and MMPs. The in vivo efficacy of these drugs varied with CMT structure and was significantly correlated with bone resorption: r2 = -0.77, P<0.01; gelatinase inhibitory activity: r2 = -0.84, P <0.01; and serum drug concentrations.

CONCLUSION

Since both conventional (antimicrobial) and non-antimicrobial tetracyclines inhibited periodontal bone resorption induced by endotoxin injection, MMP-mediated bone loss in this model can be prevented by inhibition of MMPs.

Chlortetracycline modulates acute phase response of ex vivo perfused pig livers, and inhibits TNF-alpha secretion by isolated Kupffer cells

Tetracyclines have been shown to have anti-inflammatory effects in addition to their antimicrobial action. We investigated the effects of in vivo administration of chlortetracycline (CTC) on ex vivo perfused pig livers. The retention and clearance of Salmonella choleraesuis, production of acute phase proteins C-reactive protein (CRP), and haptoglobin (HPG) by whole livers were studied. The in vitro modulation by CTC of TNF-alpha secretion by pig Kupffer cells (KC) was also studied. Pigs were dosed orally with CTC for three days, and given injections of Salmonella LPS 24 h before removal of the liver. Salmonella retention and clearance by livers of pigs given CTC was lower than by control livers (p < 0.01 and p < 0.05, respectively). We demonstrated an increase of CRP and HPG by livers from control pigs after a three-hour perfusion while pigs from CTC pretreated pigs varied in this response. Further, CTC decreased the secretion of TNF-alpha by cultured KC incubated in vitro with LPS. Modulation of TNF-alpha production by CTC suggests a potential for attenuating the inflammatory response. However, this possible beneficial action of CTC was accompanied by a significant decline in the antimicrobial effect of the liver.

Effects of sex hormones on production of interleukin-1 by human peripheral monocytes

BACKGROUND

Interleukin-1 (IL-1) is a potent mediator of inflammation and is known to induce bone resorption. We studied the effects of sex hormones on the function of human monocytes and demonstrated that prostaglandin E2 (PGE2) production was enhanced by progesterone and estradiol. As PGE2 has been shown to suppress the production of IL-1 by monocytes, it was speculated that sex hormones also modify the production of IL-1 by regulating PGE2 production. Thus, the effects of sex hormones on the production of IL-1 from human peripheral monocytes and the influence of PGE2 were investigated.

METHODS

Mononuclear leukocytes were obtained from 22 healthy adults. Progesterone, 17-beta estradiol (estradiol), and testosterone were used as representative sex hormones. Monocytes were incubated at 37 degrees C in air with 5% CO2 for 24 hours in RPMI 1640 medium with sex hormones at the designated concentrations. LPS (Salmonella typhimurium) was used to stimulate the monocytes at a concentration of 10 microg/ml. The concentrations of IL-1alpha and IL-1beta in the medium were determined by enzyme-linked immunosorbent assay kits. The concentration of PGE2 was determined using a direct radio-immunoassay kit. Indomethacin was used to inhibit the synthesis of PGE2 and eliminate its effect on the production of IL-1.

RESULTS

Estradiol at concentrations of 0.04 ng/ml or more significantly reduced both IL-1alpha and IL- 1beta production. Progesterone also reduced IL-1alpha and IL-1beta production significantly at concentrations of 0.1 ng/ml or more and 0.02 ng/ml or more, respectively. The reductions in IL- 1alpha and IL-1beta production by sex hormones were not affected by addition of indomethacin.

CONCLUSIONS

Estradiol and progesterone inhibited the production of IL-1 from human peripheral monocytes. The inhibition was not the result of enhanced production of PGE2. Under conditions in which sex hormone levels are low, monocytes produce IL- more readily in response to stimulation by LPS than high levels of such hormones. Low concentrations of sex hormones may be considered as one of the risk factors for periodontitis.

Tumor necrosis factor alpha and nucleus-pulposus-induced nerve root injury

STUDY DESIGN

The effects of nucleus pulposus and various treatments to block tumor necrosis factor alpha activity were evaluated in an experimental set-up using immunohistochemistry and nerve conduction velocity recordings.

OBJECTIVES

To assess the presence of tumor necrosis factor alpha in pig nucleus pulposus cells, and to see if block of tumor necrosis factor alpha also blocks the nucleus-pulposus-induced reduction of nerve root conduction velocity.

SUMMARY AND BACKGROUND DATA

A meta-analysis of observed effects induced by nucleus pulposus revealed that these effects might relate to one specific cytokine-tumor necrosis factor alpha.

METHODS

Series-1: Cultured nucleus pulposus cells were stained immunohistologically with a monoclonal antibody for tumor necrosis factor alpha. Series-2: Nucleus pulposus was harvested from lumbar discs and applied to the sacrococcygeal cauda equina in 13 pigs autologously. Four pigs received 100 mg of doxycycline intravenously; five pigs had a blocking monoclonal antibody to tumor necrosis factor alpha applied locally in the nucleus pulposus, and four pigs remained nontreated, forming a control group. Three days after the application, the nerve root conduction velocity was determined over the application zone by local electrical stimulation.

RESULTS

Series-1: Tumor necrosis factor alpha was found to be present in the nucleus pulposus cells. Series-2: The selective antibody to tumor necrosis factor alpha limited the reduction of nerve conduction velocity, although in comparison with the control group this was not statistically significant. However, treatment with doxycycline significantly blocked the nucleus-pulposus-induced reduction of conduction velocity.

CONCLUSION

For the first time, a specific substance, tumor necrosis factor alpha, has been linked to the nucleus-pulposus-induced effects of nerve roots after local application. Although the effects of this substance may be synergistic with those of other similar substances, the data of the current study may be of significant importance for the continued understanding of nucleus pulposus' biologic activity, and of possible potential use for future strategies in managing sciatica.

In vivo exposure to Porphyromonas gingivalis up-regulates nitric oxide but suppresses tumour necrosis factor-alpha production by cultured macrophages

The present study was designed to test whether the functional response of mouse macrophages elicited by chronic exposure to bacteria will be different from that of cells elicited by a non-bacterial irritant. Macrophage elicitation was conducted by Porphyromonas gingivalis, a major periodontal pathogen, in comparison to a standard elicitation by thioglycollate (TG). We measured lipopolysaccharide (LPS)-induced nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha) secretion by the elicited macrophages, and the expression of inflammatory cytokines in the whole elicited cell population. In addition, we tested the response of TG-elicited macrophages to pretreatment with P. gingivalis LPS in vitro. Mouse peritoneal macrophages were harvested 4 days after intraperitoneal injection of TG or heat-killed P. gingivalis. TG-elicited macrophages produced undetectable levels of TNF-alpha and approximately 0.5 microM of NO. The stimulation of the macrophages with LPS resulted in the secretion of NO and TNF-alpha in a dose-dependent manner. The P. gingivalis-elicited macrophages produced basal levels of approximately 5 microM NO, but TNF-alpha was not detectable. LPS stimulation of these cells further increased the secretion of NO eightfold while TNF-alpha remained undetectable. The NO secretion by P. gingivalis-elicited cells was significantly higher than that by TG-elicited cells. Examination of cytokine expression in the whole elicited cell population revealed that both P. gingivalis-elicited cells and TG-elicited cells expressed messenger RNA for interleukin-2 (IL-2), TNF-alpha and interferon-gamma (IFN-gamma), but not for IL-4. IL-6 was expressed in P. gingivalis-elicited cells only. Pretreatment of TG-elicited macrophages with P. gingivalis LPS for 24 hr prior to a second LPS challenge resulted in down-regulation of TNF-alpha secretion and up-regulation of NO secretion, a response similar to that seen in P. gingivalis-elicited peritoneal macrophages. The results suggest that the in vivo exposure of resident macrophages to P. gingivalis induces functional changes in peritoneal macrophages. These changes might be due to the effect of P. gingivalis LPS.