Effects of TNFalpha and prostaglandin E2 on the expression of MMPs in human periodontal ligament fibroblasts

Beneficial Effects of Melatonin on Periodontitis Management: Far More Than Oral Cavity

Periodontitis as a highly prevalent chronic infection/inflammatory disease can eventually lead to tooth loss and masticatory dysfunction. It also has a negative impact on general health and largely impairs quality of life. The tissue destruction during periodontitis is mainly caused by the excessive immune-inflammatory response; hence, how to modulate the host's reaction is of profound importance for effective periodontal treatment and tissue protection. Melatonin, as an endogenous hormone exhibiting multiple biological functions such as circadian rhythm regulation, antioxidant, and anti-inflammation, has been widely used in general healthcare. Notably, the past few years have witnessed increasing evidence for the application of melatonin as an adjunctive approach in the treatment of periodontitis and periodontitis-related systemic comorbidities. The detailed underlying mechanisms and more verification from clinical practice are still lacking, however, and further investigations are highly required. Importantly, it is essential to establish standard guidelines in the near future for the clinical administration of melatonin for periodontal health and general wellbeing.

Zymography and Reverse Zymography for Testing Proteases and Their Inhibitors

Zymography is a powerful technique for the assay of different hydrolases that act upon any biological macromolecule. In particular, zymography is used to assay the activities of serine proteases, e.g., matrix metalloproteinases (MMPs), and reverse zymography is used for tissue inhibitors of metalloproteinases (TIMPs) in multifarious experimental samples. Zymography is a method of electrophoretic separation of proteases under non-reducing conditions in a polyacrylamide gel containing substrate. The resolved proteins are renatured by exchange of the anionic detergent with a nonionic one, and the gel is incubated in a specific buffer for the specific proteases. After staining the gel by Coomassie blue staining solution, the proteolytic activities are visualized as clear colorless bands against a dark background. In contrast, reverse zymography is a parallel technique to detect protease inhibitors. In addition to substrate gelatin, proteases (i.e., MMPs) are also incorporated in proper ratio into the polyacrylamide gel. After electrophoresis, during the developing step, the MMPs specifically digest the substrate in regions where TIMPs are absent. Thus, inhibitors/TIMP is represented as dark zones of inhibition against a transparent background after staining. In this chapter, common troubleshoots during sample preparation, running zymography, and data interpretation are discussed. Notes are specified to enhance the sensitivity of the methods. In conclusion, zymography could be crucial for enzyme assay at the nanogram level and for the improvement of new investigative techniques for diseases such as endometriosis, rheumatoid arthritis, osteoarthritis, tumor invasion, and inflammation.

Influence of Gestational Hormones on the Bacteria-Induced Cytokine Response in Periodontitis

Periodontitis is an inflammatory disease that affects the supporting structures of teeth. The presence of a bacterial biofilm initiates a destructive inflammatory process orchestrated by various inflammatory mediators, most notably proinflammatory cytokines, which are upregulated in the gingival crevicular fluid, leading to the formation of periodontal pockets. This represents a well-characterized microbial change during the transition from periodontal health to periodontitis; interestingly, the gestational condition increases the risk and severity of periodontal disease. Although the influence of periodontitis on pregnancy has been extensively reviewed, the relationship between pregnancy and the development/evolution of periodontitis has been little studied compared to the effect of periodontitis on adverse pregnancy outcomes. This review is aimed at summarizing the findings on the pregnancy-proinflammatory cytokine relationship and discussing its possible involvement in the development of periodontitis. We address (1) an overview of periodontal disease, (2) the immune response and possible involvement of proinflammatory cytokines in the development of periodontitis, (3) how bone tissue remodelling takes place with an emphasis on the involvement of the inflammatory response and metalloproteinases during periodontitis, and (4) the influence of hormonal profile during pregnancy on the development of periodontitis. Finally, we believe this review may be helpful for designing immunotherapies based on the stage of pregnancy to control the severity and pathology of periodontal disease.

Analysis of galectin-3 levels as a source of coronary heart disease risk during periodontitis

BACKGROUND AND OBJECTIVE

Different evidence has shown that Galectins have a key role as modulators of cell surface functions and signaling in a wide range of inflammatory diseases during their preclinical stages. The aim of this study was to analyze the association and impact of periodontitis and coronary heart disease (CHD) on salivary and serum Galectin-3 in patients with periodontitis and CHD.

MATERIALS AND METHODS

For the present study, healthy controls (n = 38), periodontitis (n = 40), CHD (n = 39), and a combination of periodontitis +CHD (n = 38) patients were enrolled and analyzed. In each patient, demographic characteristics and a full-mouth clinical periodontal examination were achieved. Moreover, serum and salivary samples were collected to assess Galectin-3 and Endothelin-1 (ET-1) levels. The Jonckheere-Terpstra p-trend and Spearman's correlation tests as well as uni- and linear regression analyses were used to analyze the study data.

RESULTS

Patients with periodontitis (serum, p = .003; saliva, p < .001) and periodontitis + CHD groups (serum p = .004; saliva, p < .001) had higher median serum and salivary concentrations of Galectin-3 in comparison with CHD and healthy controls. Serum (p = .006) and salivary (p = .009) Galectin-3 levels were significantly correlated with serum ET-1. The multivariate regression analysis highlighted that periodontitis (p = .047) was the significant predictor of serum Galectin-3 levels while ET-1 (p = .028) was the significant predictor of salivary Galectin-3 levels.

CONCLUSION

The results showed that patients with periodontitis and periodontitis + CHD presented significant higher serum and salivary Galectin-3 levels in comparison with CHD patients and healthy subjects. Periodontitis and ET-1 were the significant predictors of serum and salivary Galectin-3 levels, respectively.

Effect of probiotic Lactobacillus rhamnosus by-products on gingival epithelial cells challenged with Porphyromonas gingivalis

OBJECTIVE

Probiotics are usually given as living cells, but their effects may be also achieved by postbiotics. We hypothesized that probiotics products (spent media and lysate) altered the response induced by P. gingivalis in gingival epithelial cells (GECS).

METHODS

Immortalized human OBA-9 GECs (∼2,5 × 10⁵cells/well) were challenged with P. gingivalis ATCC33277, and co-infected with L. rhamnosus Lr-32 for 4 h. L. rhamnosus Lr-32 spent medium or cells lysate was added to GECs co-infected with P. gingivalis. Another set of OBA-9 GECs were first exposed to P. gingivalis ATCC 33277 and then to the living probiotic or probiotic products. Transcription of genes encoding inflammatory mediators (IL-1β, TNF-α, IL-6, and CXCL-8) and receptors (TLR2 and TLR4) were evaluated by RT-qPCR. P. gingivalis growth under L. rhamnosus Lr-32 postbiotics was also evaluated.

RESULTS

L. rhamnosus Lr-32 spent media decreased cell viability, while living cells and cell lysates did not. L. rhamnosus Lr-32 lysate, but not spent media, upregulated transcription of inflammatory mediators (IL-1β, TNF-α, IL-6, and CXCL-8) in GECs infected with P. gingivalis. Transcription of TRL2 was upregulated in all experimental groups compared to control, whereas TLR4 was upregulated by the probiotic or its postbiotics in P. gingivalis infected cells. Spent media and lysates reduced the growth of P. gingivalis.

CONCLUSION

L. rhamnosus Lr-32 cell components rather than live probiotic enhanced the expression of inflammatory mediators in P. gingivalis infected gingival epithelial cells. The increased potential of Lr-32 cell lysates to promote immune response to the periodontopathogen may favor pathogen elimination but may also lead to additional deleterious effects of the exacerbated inflammation.

Evaluation of galectin-3, peptidylarginine deiminase-4 and tumor necrosis factor-α levels in gingival crevicular fluid for periodontal health, gingivitis and stage III grade C periodontitis: A pilot study

BACKGROUND

Comparing the gingival crevicular fluid (GCF) levels of galectin-3, peptidylarginine deiminase 4 (PAD4) and tumor necrosis factor-alpha (TNF-α) in individuals with stage III grade C periodontitis and gingivitis and with healthy periodontium was the purpose of this clinical research.

METHODS

Sixty systemically healthy and non-smoker individuals consisting of stage III grade C periodontitis (group S3P/n = 20), gingivitis (group G/n = 20), and periodontally healthy (group HP/n = 20) were recruited for this research. Clinical parameters such as probing depth, clinical attachment level, gingival index, plaque index, and bleeding on probing were recorded in periodontal charts. Enzyme-linked immunosorbent assay method was used in evaluating the GCF levels of galectin-3, PAD4, and TNF-α for study groups.

RESULTS

The GCF galectin-3 total amount was highest in group S3P compared with group G and group HP (P <0.05). Its total amount was also higher in group G compared with group HP (P <0.05). The GCF PAD4 total amount was higher in group S3P compared with group HP (P <0.05) but was similar with group G (P >0.05). Its total amounts were also similar in group G and group HP (P >0.05). The GCF TNF-α total amounts were similar in group S3P and group G (P >0.05) but significantly greater than the group HP (P ˂0.05). The GCF galectin-3, PAD4, and TNF-α concentrations were lower in the group S3P and group G compared with the group HP (P <0.05). There were significant positive correlations between GCF galectin-3 total amount and all clinical parameters (P ˂0.01) and also between GCF galectin-3 and TNF-α total amounts (P ˂0.01). There was no correlation between PAD4 and clinical parameters, or between PAD4 and TNF-α (P >0.05).

CONCLUSIONS

Galectin-3 and PAD4 may be involved in the periodontal disease pathogenesis considering the elevated levels of these molecules in periodontal disease. These biomarkers may be used in the diagnosis of periodontal diseases.

The Influence of Diet on Oxidative Stress and Inflammation Induced by Bacterial Biofilms in the Human Oral Cavity

The article is a concise compendium of knowledge on the etiology of pathogenic microorganisms of all complexes causing oral diseases. The influence of particular components of the diet and the role of oxidative stress in periodontal diseases were described. The study investigated the bacteriostatic effect of the diet of adults in in vivo and in vitro tests on the formation of bacterial biofilms living in the subgingival plaque, causing diseases called periodontitis. If left untreated, periodontitis can damage the gums and alveolar bones. Anaerobic bacteria, called periopathogens or periodontopathogens, play a key role in the etiopathogenesis of periodontitis. The most important periopathogens of the oral microbiota are bacteria of all complexes, including the red complex. The obtained results suggest the possibility of using a specific diet in the prevention and treatment of periodontal diseases-already treated as a disease of civilization. The quoted article is an innovative compilation of knowledge on this subject and it can be a valuable source of knowledge for professional hygienists, dentists, peridontologists, dentistry students and anyone who cares about proper oral hygiene. The obtained results suggest the possibility of using this type of diet in the prophylaxis of the oral cavity in order to avoid periodontitis.

Effect of Subantimicrobial Dose Doxycycline Treatment on Gingival Crevicular Fluid Levels of MMP-9 and MMP-13 in Periodontitis Stage 2, Grade B in Subjects with Type 2 Diabetes Mellitus

The aim of this study was to investigate the effect of using subantimicrobial dose doxycycline as an adjunct in periodontitis stage 2, grade B in subjects with type 2 diabetes mellitus. A total of thirty patients were divided into the following two groups with reference to periodontitis, type 2 diabetes mellitus, and administration of the doxycycline drug: Group I: patients with periodontitis stage 2, grade B and type 2 diabetes mellitus who received SRP only. Group II: patients with periodontitis stage 2, grade B and type 2 diabetes mellitus who received SRP and doxycycline 20 mg. The following clinical measurements were recorded at baseline (prior to scaling and root planning) and after one and three months postoperatively: GI, PI, and PD with a periodontal calibrated probe. The levels of both MMP-9 and MMP-13, from 60 GCF samples, were analyzed by ELISA. Patients treated with SRP and doxycycline 20 mg showed a significant reduction of PD, PI, GI, MMP-9, and MMP-13 than patients who received SRP only. Improvements in parameters clinically and biochemically were observed following the adjunctive use of doxycycline subantimicrobial dose therapy for the management of stage 2, grade B periodontitis patients with type 2 diabetes mellitus.

CREB activation affects mesenchymal stem cell migration and differentiation in periodontal tissues due to orthodontic force

During the orthodontic tooth movement, cells in periodontal ligament could differentiate into osteoblasts to synthesize alveolar bone as well as affect the proliferation, migration and differentiation of mesenchymal stem cells, which also contribute to bone remodeling. However, the mechanism is still largely elusive. Here, we evaluated the expression of CREB at the tension site of mouse periodontal ligament under orthodontic mechanical strain and in the cyclic tension strain treated human periodontal ligament cells. Then, through gain and loss of function analysis, we revealed that CREB in PDLCs promotes SDF-1 and FGF2 secretion, which enhance the migration and osteoblastic differentiation of BMSCs. We further discovered that CREB transcriptionally activates FGF2 and SDF-1 expressions by binding to the promoter regions.In conclusion, this study confirms that CREB is an upregulated gene in periodontal ligament under orthodontic tension strain stimulation and plays an important role in regulating BMSCs' physiological activity in orthodontic tension strain-induced bone formation.

Assessment of saliva and gingival crevicular fluid soluble urokinase plasminogen activator receptor (suPAR), galectin-1, and TNF-α levels in periodontal health and disease

OBJECTIVE

The aim of the study is to evaluate saliva and gingival crevicular fluid (GCF) levels of suPAR and galectin-1 in different periodontal health status and relationship between these molecules and TNF-α to understand the roles of these molecules in periodontal inflammation process.

BACKGROUND

Soluble urokinase plasminogen activator receptor (suPAR) has been described as a biological marker of inflammation and immunological activation. Galectin-1, a member of the galectin family, is an anti-inflammatory cytokine. However, to date, levels of these two molecules in periodontal health and disease have not been well documented.

METHODS

A total of 60 individuals, 20 with chronic periodontitis (group P), 20 with gingivitis (group G), and 20 with healthy periodontium (group H) were recruited for this study. Full-mouth clinical periodontal measurements were recorded in periodontal charts. GCF and whole saliva samples were collected to determine the levels of suPAR, galectin-1, and TNF-α in study groups using enzymelinked immunosorbent assay (ELISA) method.

RESULTS

The GCF total amount of suPAR, galectin-1, and TNF-α in GCF was similar in group P and G (P > .05). The GCF total amounts of these molecules in GCF were higher in the group G and P compared to the group H (P < .05), whereas the GCF concentrations of suPAR and galectin-1 were lower in the group G and P compared to the group H (P < .05).The saliva concentration of suPAR was significantly higher in group P compared to the group G and H (P < .05). It was also higher in the group G compared to the group H but there is no significant difference between the groups (P > .05). Salivary galectin-1 levels were similar in the study groups (P > .05).

CONCLUSION

Increased levels of GCF suPAR, galectin-1, and saliva suPAR in periodontal disease suggest that these molecules may play a role in the periodontal inflammation. suPAR and galectin-1 may be considered as potential biomarkers in periodontal disease.

Periodontal complications with obesity

The purpose of this paper was to identify and summarize current evidence describing periodontal complications associated with obesity. Electronic searches supplemented with manual searches were carried out to identify relevant systematic reviews. Identification, screening, eligibility, and inclusion of studies were performed independently by two reviewers. A MeaSurement Tool to Assess systematic Reviews (AMSTAR) was used to assess the quality and risk of bias of the included reviews. From 430 titles and abstracts screened, 14 systematic reviews were considered as eligible for inclusion in this meta-review. Eight reviews reported on cross-sectional studies investigating the association of obesity and periodontal diseases, 4 included longitudinal studies, 5 addressed response to periodontal therapy, 5 reported on studies investigating biomarkers, and only 2 were related to pediatric population samples. Systematic review summaries in the various study design domains (cross-sectional, longitudinal and experimental) report that obese individuals are more likely to have periodontal diseases, with more severe periodontal conditions, than nonobese individuals, with cross-sectional evidence congruent with longitudinal studies showing that obesity or weight gain increases the risk of periodontitis onset and progression. Published research on the effect of obesity on responses to periodontal therapy, or systemic or local biomarkers of inflammation, is variable and therefore inconclusive based on the evidence currently available, which suggests that overweight/obesity contributes to periodontal complications independently of other risk factors, such as age, gender, smoking, or ethnicity. This evidence supports the need for risk assessments for individual patients to facilitate personalized approaches in order to prevent and treat periodontal diseases.

Interleukin-34 levels in gingival crevicular fluid and plasma in periodontal health and disease with and without type-2 diabetes mellitus

AIM

The aim of the present study was to evaluate and correlate the levels of interleukin-34 (IL-34) in gingival crevicular fluid (GCF) and plasma in chronic periodontitis (CP) patients with and without type-2 diabetes mellitus (DM).

METHODS

A total of 175 patients were divided into five groups: (a) group I had 35 periodontally-healthy patients; (b) group II had 35 chronic gingivitis patients; (c) group III had 35 CP patients without type-2 DM; (d) group IV had 35 CP patients with type-2 DM; and (e) group V had 35 type-2 DM patients without CP. The GCF and plasma levels of IL-34 were quantified using enzyme-linked immunosorbent assay. Clinical and systemic parameters, such as gingival index, probing pocket depth, clinical attachment loss, and glycated hemoglobin levels, were evaluated.

RESULTS

The mean IL-34 concentration in GCF and plasma was highest for group IV, followed by groups III, V, and II, and lowest in group I. The difference between them was statistically significant (P < .05). There was a positive correlation between IL-34 concentration in GCF and plasma in the study groups, with the exception of group I, for which there was a negative correlation.

CONCLUSION

IL-34 can be considered a possible GCF and plasma inflammatory biomarker of periodontal disease progression and DM.

Single-channel Recordings of TREK-1 K+ Channels in Periodontal Ligament Fibroblasts

The periodontal ligament (PDL) works as a suspensory ligament when external mechanical stress is placed on the teeth. PDL fibroblasts, the principal cells in the PDL, are responsible for many PDL functions. We hypothesized that mechanosensitive ion channels are present in human PDL fibroblasts, which are capable of responding to mechanical stress during normal function of the tissue. Using patch-clamp techniques, we detected mechanosensitive TREK-1 K+ channels (a member of the two-pore-domain K+ channel family), whose single-channel conductance was 104 pS in symmetrical K+-rich solutions. The open probability of the channel was low in the quiescent state, but it was strongly increased by the induction of membrane stretch. Arachidonic acid also enhanced the channel activity. RT-PCR and immunocytochemical observations showed the expression of TREK-1 K+ channels in PDL fibroblasts. The results suggest that the activation of TREK-1 K+ channels by masticatory stress contributes to the hyperpolarization of PDL fibroblasts.

Matrix metalloproteinases in the brain and blood-brain barrier: Versatile breakers and makers

Matrix metalloproteinases are versatile endopeptidases with many different functions in the body in health and disease. In the brain, matrix metalloproteinases are critical for tissue formation, neuronal network remodeling, and blood-brain barrier integrity. Many reviews have been published on matrix metalloproteinases before, most of which focus on the two best studied matrix metalloproteinases, the gelatinases MMP-2 and MMP-9, and their role in one or two diseases. In this review, we provide a broad overview of the role various matrix metalloproteinases play in brain disorders. We summarize and review current knowledge and understanding of matrix metalloproteinases in the brain and at the blood-brain barrier in neuroinflammation, multiple sclerosis, cerebral aneurysms, stroke, epilepsy, Alzheimer's disease, Parkinson's disease, and brain cancer. We discuss the detrimental effects matrix metalloproteinases can have in these conditions, contributing to blood-brain barrier leakage, neuroinflammation, neurotoxicity, demyelination, tumor angiogenesis, and cancer metastasis. We also discuss the beneficial role matrix metalloproteinases can play in neuroprotection and anti-inflammation. Finally, we address matrix metalloproteinases as potential therapeutic targets. Together, in this comprehensive review, we summarize current understanding and knowledge of matrix metalloproteinases in the brain and at the blood-brain barrier in brain disorders.

Activation of Receptor Activator of Nuclear Factor-κB Ligand and Matrix Metalloproteinase Production in Periodontal Fibroblasts by Endothelin Signaling

BACKGROUND

Periodontitis is a group of inflammatory diseases affecting the tissues supporting the teeth that will progressively cause the loss of alveolar bone and periodontal ligaments and eventually the dentition. Activation of osteoclast activity by receptor activator of nuclear factor-κB ligand (RANKL) and released enzymes such as matrix metalloproteinases (MMPs) are among the factors involved in the breakdown of the periodontium. However, the mechanisms regulating their production in periodontitis are poorly understood. Endothelin signaling via the activation of the endothelin-A receptor (EDNRA) by endothelin-1 may play a role in the disease because the expression of the receptor and ligand is elevated in the periodontal tissues of patients with periodontitis.

METHODS

Cultured primary human periodontal fibroblasts were treated with 20 and 100 nM endothelin-1 for 6 and 24 hours and then collected to assess MMP and RANKL production by immunoblotting. Inhibitors were used to identify the molecular pathways activated by EDNRA in these cells.

RESULTS

Endothelin-1 stimulated the production of MMP1, MMP8, and RANKL in a dose- and time-dependent manner; blocking EDNRA function with the antagonist TBC3214 inhibited the response, although EDNRA activation had no effects on osteoprotegerin production. These mechanistic studies indicate that EDNRA activates phospholipase C, which then 1) increases the MMP1 protein levels through activation of the extracellular signal-regulated kinase mitogen-activated protein kinase-dependent pathway and 2) upregulates RANKL by a different pathway.

CONCLUSION

These results suggest that EDNRA may function in the breakdown of the periodontal tissues associated with periodontitis by promoting the protein expression of MMPs and RANKL via the phospholipase C pathway.

Green tea catechin inhibits the activity and neutrophil release of Matrix Metalloproteinase-9

Green tea (Camellia sinensis; 綠茶 lǜ chá) extracts have been shown to possess anti-oxidant and anti-inflammatory effects in various cell types. Green tea extract (GTX) has been shown to significantly inhibit the activity of collagenase-3 (matrix metalloproteinase-13 (MMP-13)) in vitro. MMPs, such as MMP-9, are known to be involved in many inflammatory diseases including periodontal disease. GTX and a major catechin, epigallocatechin-gallate (EGCG), were examined for their ability to inhibit purified MMP-9 activity and its release from stimulated neutrophils.

Methanol extract of Green tea and commercially purchased EGCG (>95 % purity) were tested in vitro for their ability to inhibit MMP-9 activity and/or its release from neutrophils using a β-casein cleavage assay and gelatin zymography, respectively. Statistical analysis was performed by Student's t-test.

GTX and EGCG at 0.1% (w/v) completely inhibited the activity of MMP-9. In addition, GTX and EGCG (0.1 %) significantly inhibited (p < 0.001) the release of MMP-9 from formyl-Met-Leu-Phe (FMLP)-stimulated human neutrophils by 62.01% ± 6.717 and 79.63% ± 1.308, respectively. The inhibitory effects of GTX and EGCG occurred in unstimulated neutrophils (52.42% ± 3.443 and 62.33% ± 5.809, respectively). When the inhibitory effect of EGCG was further characterized, it significantly inhibited the release of MMP-9 from the FMLP-stimulated human neutrophils in a dose-dependent manner.

The effects of GTX and EGCG on MMPs could be extrapolated to clinical/in vivo studies for the development of oral care products to prevent or treat chronic inflammatory diseases including periodontal diseases.

TNF-α stimulates MMP-3 production via PGE2 signalling through the NF-kB and p38 MAPK pathway in a murine cementoblast cell line

BACKGROUND

Cementoblasts are considered to play an important role in the homeostasis of periodontal tissues under both physiologic and pathologic conditions. Matrix metalloproteinases (MMPs) is the key family of enzymes participating in extracellular matrix remodelling. In the present study, the effects and regulatory mechanisms of tumour necrosis factor (TNF)-α on the expression of MMPs and their inhibitors (tissue inhibitor of metalloproteinases; TIMPs) were investigated.

MATERIALS AND METHODS

OCCM-30, an immortalised murine cementoblast cell line, was stimulated with TNF-α at 1 and 10ng/ml for 24h. The expression of Mmp-2, Mmp-3, Mmp-13, Mmp-14, Timp-1, and Timp-2 as well as PGE2 was determined. Inhibitors of MAPKs, PI3K/Akt, NF-kB and Cox-2 were employed to reveal possible TNF-α induced regulatory signalling pathway(s). The mRNA and protein expression were analysed by (semi)quantitative real-time PCR and enzyme-linked immunosorbent assay (ELISA), respectively.

RESULTS

TNF-α dose-dependently stimulated MMP-3 expression by cementoblasts. This was found for mRNA as well as protein expression. No significant differences were found in the mRNA expression of Mmp-2, Mmp-13, Mmp-14, Timp-1, and Timp-2 upon TNF-α stimulation. The level of PGE2, however, was significantly increased along with MMP-3. Treatment with a selective Cox-2 inhibitor resulted in partial suppression of TNF-α-induced Mmp-3 mRNA expression. Addition of PGE2 enhanced Mmp-3 mRNA in a dose dependent manner, suggesting an inductive effect of TNF-α partly via PGE2. The up-regulation of Mmp-3 by TNF-α was completely suppressed by a combination of NF-kB and p38 MAPK inhibitors, while partial suppression was found with each inhibitor. The effect of PGE2 on Mmp-3 expression was abolished by treating cells with an NF-kB inhibitor; a p38 MAPK inhibitor had only a small effect.

CONCLUSIONS

The present study indicates that cementoblasts respond to TNF-α by increasing MMP-3 production partially via PGE2 and signalling through the NF-kB and p38 MAPK pathway. MMP-3 may participate in periodontal tissue degradation/remodelling.

Multilevel regulation of matrix metalloproteinases in tissue homeostasis indicates their molecular specificity in vivo

The matrix metalloproteinases (MMPs) play a crucial role in irreversible remodeling of the extracellular matrix (ECM) in normal homeostasis and pathological states. Accumulating data from various studies strongly suggest that MMPs are tightly regulated, starting from the level of gene expression all the way to zymogen activation and endogenous inhibition, with each level controlled by multiple factors. Recent in vivo findings indicate that cell-ECM and cell-cell interactions, as well as ECM bio-active products, contribute an additional layer of regulation at all levels, indicating that individual MMP expression and activity in vivo are highly coordinated and tissue specific processes.

Differentiated embryonic chondrocytes 1 expression of periodontal ligament tissue and gingival tissue in the patients with chronic periodontitis

OBJECTIVE

To evaluate the DEC1 expression of periodontal ligament tissue and gingival tissue in the patients with chronic periodontitis.

METHODS

20 non-smoking patients with chronic periodontitis and 20 healthy individuals were enrolled. Periodontal ligament tissue and gingival tissue samples from healthy subjects were collected during teeth extraction for orthodontic reason or the third molar extraction. The parallel samples from patients with chronic periodontitis were obtained during periodontal flap operations or teeth extraction as part of periodontal treatment. The DEC1 expression and the alkaline phosphatase (ALP) activity of both the periodontal ligament tissue and gingival tissue were determined by Western blot, Immunohistochemistry and ALP Detection Kit.

RESULTS

The DEC1 expression of periodontal ligament tissue in the patients with chronic periodontitis decreased significantly along with the decreased ALP activity. On the contrary, the DEC1 expression of gingival tissue in the patients with chronic periodontitis increased significantly. Further study found that the DEC1 expression of gingival tissue increased mainly in the suprabasal layer of gingival epithelial cells but decreased in the gingival connective tissue of the patients with chronic periodontitis.

CONCLUSION

The DEC1 expression decreases in the periodontal ligament tissue which is related to the osteogenic capacity, whereas the DEC1 expression increases in the suprabasal layer of gingival epithelial cells which are involved in immune inflammatory response in the patients with chronic periodontitis. The findings provide a new target to explore the pathology and the therapy of periodontitis.

Host-derived biomarkers in gingival crevicular fluid for complementary diagnosis of apical periodontitis

Apical periodontitis (AP) develops as a result of the host’s immune inflammatory response to pulpal infection of the dental root canals that leads to the generation of an apical lesion of endodontic origin (ALEO) and potentially to systemic metabolic alterations. Misdiagnosed ALEO is not infrequent due to the lack of diagnostic tools to differentiate apical lesions of different natures. Despite the conservative endodontic treatment shows a high success rate, there are refractory cases that can not be identified early enough during follow up. This evidences the need to develop complementary diagnostic tools, such as oral fluid biomarker analysis. Gingival crevicular fluid (GCF) is a serum transudate that becomes an exudate under inflammatory conditions, carrying molecules from local periodontal tissues and general circulation than can be harvested non-invasively. We aimed to review the available literature analyzing GCF composition in AP patients to evaluate whether GCF has any potential for complementary diagnosis. To the date, only few studies addressing changes of GCF components in AP are available. Most studies support GCF modifications in specific components in AP-affected teeth, suggesting that it might reflect periapical inflammation. GCF has potential for diagnostic tool, treatment follow-up and eventually to assess systemic comprise.

Biomechanical adaptation of the bone-periodontal ligament (PDL)-tooth fibrous joint as a consequence of disease

In this study, an in vivo ligature-induced periodontitis rat model was used to investigate temporal changes to the solid and fluid phases of the joint by correlating shifts in joint biomechanics to adaptive changes in soft and hard tissue morphology and functional space. After 6 and 12 weeks of ligation, coronal regions showed a significant decrease in alveolar crest height, increased expression of TNF-α, and degradation of attachment fibers as indicated by decreased collagen birefringence. Cyclical compression to peak loads of 5-15N at speeds of 0.2-2.0mm/min followed by load relaxation tests showed decreased stiffness and reactionary load rate values, load relaxation, and load recoverability, of ligated joints. Shifts in joint stiffness and reactionary load rate increased with time while shifts in joint relaxation and recoverability decreased between control and ligated groups, complementing measurements of increased tooth displacement as evaluated through digital image correlation. Shifts in functional space between control and ligated joints were significantly increased at the interradicular (Δ10-25μm) and distal coronal (Δ20-45μm) regions. Histology revealed time-dependent increases in nuclei elongation within PDL cells and collagen fiber alignment, uncrimping, and directionality, in 12-week ligated joints compared to random orientation in 6-week ligated joints and to controls. We propose that altered strains from tooth hypermobility could cause varying degrees of solid-to-fluid compaction, alter dampening characteristics of the joint, and potentiate increased adaptation at the risk of joint failure.

The role of osteoimmunology in periodontal disease

Periodontal disease is a pathological condition that involves inflammation of the tooth supporting structures. It occurs in response to the presence of bacterial plaque on the tooth structure. The host defense system, including innate and adaptive immunity, is responsible for combating the pathologic bacteria invading the periodontal tissue. Failure to eradicate the invading pathogens will result in a continuous state of inflammation where inflammatory cells such as lymphocytes, PMNs, and macrophages will continue to produce inflammatory mediators in an effort to destroy the invaders. Unfortunately, these inflammatory mediators have a deleterious effect on the host tissue as well as foreign microbes. One of the effects of these mediators on the host is the induction of matrix degradation and bone resorption through activation of proteases and other inflammatory mediators that activate osteoclasts.

Inflammatory mediators in the pathogenesis of periodontitis

Periodontitis is a chronic inflammatory condition of the periodontium involving interactions between bacterial products, numerous cell populations and inflammatory mediators. It is generally accepted that periodontitis is initiated by complex and diverse microbial biofilms which form on the teeth, i.e. dental plaque. Substances released from this biofilm such as lipopolysaccharides, antigens and other virulence factors, gain access to the gingival tissue and initiate an inflammatory and immune response, leading to the activation of host defence cells. As a result of cellular activation, inflammatory mediators, including cytokines, chemokines, arachidonic acid metabolites and proteolytic enzymes collectively contribute to tissue destruction and bone resorption. This review summarises recent studies on the pathogenesis of periodontitis, with the main focus on inflammatory mediators and their role in periodontal disease.

Correlation of expression and activity of matrix metalloproteinase-9 and -2 in human gingival cells of periodontitis patients

Purpose

Matrix metalloproteinases (MMPs) are capable of degrading extracellular matrix, and they are inducible enzymes depending on an inflammatory environment such as periodontitis and bacterial infection in periodontal tissue. Gingival inflammation has been postulated to be correlated with the production of MMP-2 and MMP-9. The objective of this study was to quantify the expression and activity of MMP-9 and -2, and to determine the correlation between activity and expression of these MMPs in human gingival tissues with periodontitis.

Methods

The gingival tissues of 13 patients were homogenized in 500 µL of phosphate buffered saline with a protease inhibitor cocktail. The expression and activity of MMP-2 and -9 were measured by enzyme-linked immunosorbent assay and Western blot analysis, and quantified by a densitometer. For the correlation line, statistical analysis was performed using the Systat software package.

Results

MMP-9 was highly expressed in all gingival tissue samples, whereas MMP-2 was underexpressed compared with MMP-9. MMP-9 activity increased together with the MMP-9 expression level, with a positive correlation (r=0.793, P=0.01). The correlation was not observed in MMP-2.

Conclusions

The expression of MMP-2 and -9 might contribute to periodontal physiological and pathological processes, and the degree of MMP-9 expression and activity are predictive indicators relevant to the progression of periodontitis.

Effect of Porphyromonas gingivalis and Lactobacillus acidophilus on secretion of IL1B, IL6, and IL8 by gingival epithelial cells

Porphyromonas gingivalis alters cytokine expression in gingival epithelial cells, stimulating inflammatory responses that may lead to periodontal disease. This study explored the effect of Lactobacillus acidophilus on the specific expressions of the interleukins (ILs) IL1B, IL6, and IL8 induced by the pathogen. Human gingival epithelial cells were co-cultured with P. gingivalis, L. acidophilus, or L. acidophilus + P. gingivalis; the control group consisted of the cells alone. Protein and gene expression levels of the ILs were detected using ELISA and qRT-PCR, respectively. The supernatant from the P. gingivalis group held significantly higher protein and mRNA levels of IL1B, IL6, and IL8, compared to the control group. In the mixed bacterial group (L. acidophilus + P. gingivalis), the levels of all three ILs decreased with increasing concentrations of L. acidophilus and were significantly different from the P. gingivalis group. This suggests that in gingival cells, L. acidophilus offsets the P. gingivalis-induced secretion of these ILs in a dose-dependent manner.

Nicotine and lipopolysaccharide stimulate the production of MMPs and prostaglandin E2 by hypoxia-inducible factor-1α up-regulation in human periodontal ligament cells

BACKGROUND AND OBJECTIVE

  Although hypoxia-inducible factor 1α (HIF-1α) is up-regulated in the periodontal pockets of periodontitis patients, the expression and precise molecular mechanisms of HIF-1α remain unknown in human periodontal ligament cells (PDLCs). The aim of this study was to explore the effects, as well as the signaling pathway, of nicotine and lipopolysaccharide (LPS) on the expression of HIF-1α and on the production of its target genes, including cyclooxygenase-2 (COX-2)-derived prostaglandin E(2) (PGE(2) ), MMP-2 and MMP-9 in PDLCs.

MATERIAL AND METHODS

  The expression of COX-2 and HIF-1α proteins was evaluated using western blotting. The production of PGE(2) and MMPs was evaluated using enzyme immunoassays and zymography, respectively.

RESULTS

  LPS and nicotine synergistically induced the production of PGE(2) , MMP-2 and MMP-9, and increased the expression of MMP-2, MMP-9, COX-2 and HIF-1α proteins. Inhibition of HIF-1α activity by chetomin or knockdown of HIF1α gene expression by small interfering RNA markedly attenuated the production of LPS- and nicotine-stimulated PGE(2) and MMPs, as well as the expression of COX-2 and HIF-1α. Furthermore, pretreatment with inhibitors of COX-2, p38, extracellular signal-regulated kinase, Jun N-terminal kinase, protein kinase C, phosphatidylinositol 3-kinase and nuclear factor-kappaB decreased the expression of nicotine- and LPS-induced HIF-1α and COX-2, as well as the activity of PGE(2) and MMPs.

CONCLUSION

  These data demonstrate novel mechanisms by which nicotine and LPS promote periodontal tissue destruction, and provide further evidence that HIF-1α is a potential target in periodontal disease associated with smoking and dental plaque.

Pro-oxidant status and matrix metalloproteinases in apical lesions and gingival crevicular fluid as potential biomarkers for asymptomatic apical periodontitis and endodontic treatment response

Background

Oxidative stress and matrix metalloproteinases -9 and -2 are involved in periodontal breakdown, whereas gingival crevicular fluid has been reported to reflect apical status. The aim of this study was to characterize oxidant balance and activity levels of MMP -2 and -9 in apical lesions and healthy periodontal ligament; and second, to determine whether potential changes in oxidant balance were reflected in gingival crevicular fluid from asymptomatic apical periodontitis (AAP)-affected teeth at baseline and after endodontic treatment.

Methods

Patients with clinical diagnosis of AAP and healthy volunteers having indication of tooth extraction were recruited. Apical lesions and healthy periodontal ligaments, respectively, were homogenized or processed to obtain histological tissue sections. Matrix metalloproteinase -9 and -2 levels and/or activity were analyzed by Immunowestern blot, zymography and consecutive densitometric analysis, and their tissue localization was confirmed by immunohistochemistry. A second group of patients with AAP and indication of endodontic treatment was recruited. Gingival crevicular fluid was extracted from AAP-affected teeth at baseline, after endodontic treatment and healthy contralateral teeth. Total oxidant and antioxidant status were determined in homogenized tissue and GCF samples. Statistical analysis was performed using STATA v10 software with unpaired t test, Mann-Whitney test and Spearman's correlation.

Results

Activity of MMP-2 and MMP-9 along with oxidant status were higher in apical lesions (p < 0.05). Total oxidant status correlated positively with matrix metalloproteinase-2 and lesion size (p < 0.05). Gingival crevicular fluid showed significantly lower levels of total antioxidant status in diseased teeth at baseline compared to controls and endodontically-treated groups.

Conclusions

Apical lesions display an oxidant imbalance along with increased activity of matrix metalloproteinase-2 and -9 and might contribute to AAP progression. Oxidant imbalance can also be reflected in GCF from AAP-affected teeth and was restored to normal levels after conservative endodontic treatment. These mediators might be useful as potential biomarkers for chair-side complementary diagnostic of apical status in GCF.

Dexamethasone-induced up-regulation of two-pore domain K+ channel genes, TASK-1 and TWIK-2, in cultured human periodontal ligament fibroblasts

Two-pore domain K(+) channels are widely expressed in many types of cells, and have various important functions, especially maintaining the resting membrane potential. In the previous report, we have confirmed the presence of several kinds of two-pore domain K(+) channels in the periodontal ligament (PDL) fibroblasts. It is well known that dexamethasone (Dex) regulates the functions of various kinds of ion channels. In this work, we investigate if Dex affects the gene expressions of the two-pore domain K(+) channels in the PDL fibroblasts. We also examined the effects of other steroid hormones on the K(+) channels gene expression. The mRNA levels of two-pore domain K(+) channels in human PDL fibroblasts were examined in the presence or absence of Dex by RT-PCR. The effects of other steroid hormones (aldosterone, estrogen, 1α,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)], and retinoic acid) were also examined. Dex significantly induced the expression of TASK-1 and TWIK-2 in mRNA levels in both a dose- and a time-dependent manner. The stimulatory effects of Dex were completely abolished by a glucocorticoid receptor antagonist. 1,25-(OH)(2)D(3) also increased the TASK-1 mRNA levels but had no effect on TWIK-2 expression. Dex, one of the potent glucocorticoid, probably have a protective role against external stimuli by maintaining the membrane potential of PDL fibroblasts through the up-regulation of TASK-1 and TWIK-2 K(+) channels.

Matrix metalloproteinase expression in teeth with apical periodontitis is differentially modulated by the modality of root canal treatment

INTRODUCTION

The objective of this study was to investigate the expression of matrix metalloproteinases (MMPs) in apical periodontitis and during the periapical healing phase after root canal treatment.

METHODS

Apical periodontitis was induced in dog teeth, and root canal treatment was performed in a single visit or by using an additional calcium hydroxide root canal dressing. One hundred eighty days after treatment the presence of inflammation was examined, and tissues were stained to detect bacteria. Bacterial status was correlated to the degree of tissue organization, and to further investigate molecules involved in this process, tissues were stained for MMP-1, MMP-2, MMP-8, and MMP-9. Data were analyzed by using one-way analysis of variance followed by Tukey test or Kruskal-Wallis followed by Dunn test.

RESULTS

Teeth with apical periodontitis that had root canal therapy performed in a single visit presented an intense inflammatory cell infiltrate. Periapical tissue was extremely disorganized, and this was correlated with the presence of bacteria. Higher MMP expression was evident, similar to teeth with untreated apical periodontitis. In contrast, teeth with apical periodontitis submitted to root canal treatment with calcium hydroxide presented a lower inflammatory cell infiltrate. This group had moderately organized connective tissue, lower prevalence of bacteria, and lower number of MMP-positive cells, similar to healthy teeth submitted to treatment.

CONCLUSIONS

Teeth treated with calcium hydroxide root canal dressing exhibited a lower percentage of bacterial contamination, a lower MMP expression, and a more organized extracellular matrix, unlike those treated in a single visit. This suggests that calcium hydroxide might be beneficial in tissue repair processes.

Strong and persistent microbial and inflammatory stimuli overcome the genetic predisposition to higher matrix metalloproteinase-1 (MMP-1) expression: a mechanistic explanation for the lack of association of MMP1-1607 single-nucleotide polymorphism genotypes with MMP-1 expression in chronic periodontitis lesions

AIMS

Our objective was to evaluate the association between the MMP1-1607 single-nucleotide polymorphism (SNP), periodontopathogens and inflammatory cytokines with matrix metalloproteinase-1 (MMP-1) mRNA levels in vitro and in vivo.

MATERIALS AND METHODS

This study investigated the influence of genetic (MMP1-1607 SNP), microbial (Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Actinobacillus actinomycetemcomitans) and inflammatory [tumour necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta)] factors on the determination of MMP-1 mRNA levels in periodontal tissues of non-smoker chronic periodontitis (CP, N=178) and control (C, N=190) groups. The effects of single and repeated lipopolysaccharide (LPS) and inflammatory cytokine stimulation of macrophages with distinct MMP1-1607 SNP genotypes were also investigated.

RESULTS

In healthy tissues, the MMP1-1607 2G allele was associated with higher MMP-1 levels while in CP MMP-1 levels were associated with the presence and load of periodontopathogens, and also with TNF-alpha and IL-1beta expression irrespective of the MMP1-1607 genotype. In vitro data demonstrate that in 2G macrophages low- and intermediate-dose LPS and TNF-alpha+IL-1beta stimulation was associated with increased MMP-1 expression, while strong and repeated stimulation resulted in higher MMP-1 levels irrespective of the MMP1-1607 genotype.

CONCLUSION

Our data demonstrate a limited role for MMP1-1607 SNP in periodontitis, where the extensive chronic antigenic challenge exposure overcomes the genetic control and plays a major role in the determination of MMP-1 expression.

Gingivitis and periodontitis are related to repeated high levels of circulating tumor necrosis factor-alpha in patients with rheumatoid arthritis

BACKGROUND

Several studies have indicated a relationship between rheumatoid arthritis and periodontal disease. The aim of this study was to investigate the association between the circulating proinflammatory mediators tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta, prostaglandin E(2), serotonin, rheumatoid factor, and periodontitis in patients with rheumatoid arthritis.

METHODS

Nineteen patients, 17 women and two men, with rheumatoid arthritis were included. These patients had been examined repeatedly (average of three times) with regard to inflammatory markers and mediators from blood samples. Their teeth, excluding third molars, were examined with regard to number, clinical attachment level (CAL), probing depth (PD), and gingival bleeding on probing (BOP). Assessment of furcation involvement and increased tooth mobility was also made. All patients were non-smokers. Thirty healthy individuals, 20 women and 10 men, were included as a reference regarding TNF-alpha.

RESULTS

Patients with high levels of time-averaged TNF-alpha from repeated plasma samples had a higher frequency of BOP as well as increased CAL and PD compared to those with low levels.

CONCLUSION

Gingivitis and periodontitis are related to high levels of circulating TNF-alpha in patients with rheumatoid arthritis.

Gelatinolytic activity in gingival crevicular fluid from teeth with periapical lesions

OBJECTIVE

Many matrix metalloproteinases (MMPs) have been associated with periodontal tissue destruction during chronic and apical periodontitis. The aim of this study was to determine gelatinolytic activity in gingival crevicular fluid (GCF) from teeth with apical lesions and healthy controls.

STUDY DESIGN

Case-control study.

MATERIALS AND METHODS

After clinical examination, 30 GCF samples were obtained from 20 affected and 20 control teeth. Subjects with periodontal diseases were excluded. Gelatinolytic activity was determined by gelatin zymography and densitometric analysis.

RESULTS

ProMMP-9 levels were significantly increased when compared with controls and were positively correlated with MMP-9 activity in diseased GGF. Similarly, MMP-2 activity, when detected it was exclusively in diseased samples. Additional bands of estimated molecular weights of 60 and 48 kDa were observed.

CONCLUSIONS

MMP-9 and -2 are highly increased in GCF from teeth with periapical lesions. These gelatinases could represent useful markers in monitoring chronic apical periodontitis in GCF.

MMP-13 and TIMP-1 determinations in progressive chronic periodontitis

Matrix metalloproteinase (MMP)-13 is a collagenase involved in extracellular matrix degradation either by its direct degradative effects or by processing bioactive substrates. The aim of this study was to determine the levels of MMP-13 and tissue inhibitor of metalloproteinase (TIMP)-1 in gingival crevicular fluid (GCF) and gingival biopsies obtained from active and inactive sites during chronic periodontitis progression.

MATERIALS AND METHODS

This was a longitudinal study in which chronic periodontitis patients with moderate to severe disease were included and followed until they developed progression determined by the tolerance method. GCF samples were obtained from periodontitis, active, inactive and healthy sites and additional gingival biopsies were taken from active and inactive sites. MMP-13 and TIMP-1 determinations were carried out by immunodot blots and immunowestern blots.

RESULTS

In progressive periodontitis, MMP-13 and TIMP-1 remained unchanged between active and inactive sites, but as the TIMP-1 relative levels increased together with MMP-13 elevation in inactive samples, an inverse correlation was observed in active sites. Besides, MMP-13 was undetectable in healthy controls.

CONCLUSION

Chronic periodontitis is characterized by increased MMP-13 expression. During disease progression, active sites tended to decrease TIMP-1 levels in association with MMP-13 elevation.

The presence of arachidonic acid-activated K+ channel, TREK-1, in human periodontal ligament fibroblasts

Human periodontal ligament (PDL) fibroblasts expressed following two-pore-domain K(+) channels, TWIK-2 > TREK-1 > TWIK-1 >> TASK-1 > TRAAK > TASK-2. TREK-2 message was not detectable. We found the presence of arachidonic acid-activated and mechanical stress-sensitive K(+) channel, TREK-1, in the PDL fibroblasts by patch-clamp technique. It was also found the significant increase of intracellular concentration of arachidonic acid upon the application of cyclic stretch. Therefore, we suppose that the mechanical stretch due to the mastication activates phospholipase A(2) to release arachidonic acid (AA) from membrane, then, the released AA activates TREK-1. Thus, TREK-1 K(+) channels may play a protective role to maintain the negative membrane potential of PDL fibroblasts against the environmental stimuli.

Cytokine expression pattern in compression and tension sides of the periodontal ligament during orthodontic tooth movement in humans

Orthodontic tooth movement is achieved by the remodeling of periodontal ligament (PDL) and alveolar bone in response to mechanical loading and is believed to be mediated by several host mediators, such as cytokines. By means of real-time polymerase chain reaction (PCR), we studied the pattern of expression of mRNA encoding several pro- and anti-inflammatory cytokines in relation to several extracellular matrix and bone remodeling markers, in tension (T) and compression (C) sides of the PDL of human teeth subjected to rapid maxillary expansion. The PDL of normal teeth was used as a control. The results showed that both T and C sides exhibited significantly higher expression of all targets when compared with controls, except for type I collagen (COL-I) and tissue inhibitor of metalloproteinase-1 (TIMP-1) on the C side. Comparing C and T sides, the C side exhibited higher expression of tumor necrosis factor-alpha (TNF-alpha), receptor activator of nuclear factor-kappaB ligand (RANKL), and matrix metalloproteinase-1 (MMP-1), whereas the T side presented higher expression of interleukin-10 (IL-10), TIMP-1, COL-I, osteoprotegerin (OPG), and osteocalcin (OCN). The expression of transforming growth factor-beta (TGF-beta) was similar in both C and T sides. Our data demonstrate a differential expression of pro- and anti-inflammatory cytokines in compressed and stretched PDL during orthodontic tooth movement.

Transcriptional activation of MMP-13 by periodontal pathogenic LPS requires p38 MAP kinase

Matrix metalloprotease-13 (MMP-13) is induced by pro-inflammatory cytokines and increased expression is associated with a number of pathological conditions such as tumor metastasis, osteoarthritis, rheumatoid arthritis and periodontal diseases. MMP-13 gene regulation and the signal transduction pathways activated in response to bacterial LPS are largely unknown. In these studies, the role of the mitogen-activated protein kinase (MAPK) pathways in the regulation of MMP-13 induced by lipopolysaccharide was investigated. Lipopolysaccharide from Escherichia coli and Actinobacillus actinomycetemcomitans significantly (P < 0.05) increased MMP-13 steady-state mRNA (average of 27% and 46% increase, respectively) in murine periodontal ligament fibroblasts. MMP-13 mRNA induction was significantly reduced by inhibition of p38 MAP kinase. Immunoblot analysis indicated that p38 signaling was required for LPS-induced MMP-13 expression. Lipopolysaccharide induced proximal promoter reporter (-660/+32 mMMP-13) gene activity required p38 signaling. Collectively, these results indicate that lipopolysaccharide-induced murine MMP-13 is regulated by p38 signaling through a transcriptional mechanism.

Upregulation of matrix metalloproteinase (MMP)-1 and its activator MMP-3 of human osteoblast by uniaxial cyclic stimulation

Proper mechanical loading is essential for bone remodeling and maintenance of human skeletal system. Matrix metalloproteinases (MMPs) are secreted by mesenchymal stromal lining cells and osteoblasts to prepare the initiation sites for osteoclastic bone resorption at the beginning of the remodeling cycle. However, only a few studies have addressed the effect of mechanical stress on MMPs and their endogenous tissue inhibitors of matrix metalloproteinases (TIMPs) in osteoblasts. In this study, the response of human osteoblasts to uniaxial cyclic stretching was investigated to clarify this more in detail. Stretching affected the orientation of the osteoblasts, and quantitative reverse transcription-polymerase chain reaction revealed coordinated upregulation of MMP-1 and its activator MMP-3 mRNA by cyclic 5% stretching at 3 h (p < 0.01). Upregulation of cyclooxygenase-2 mRNA was also found in response to cyclic 1 and 5% stretchings at 1, 3, and 6 h (p < 0.01). No changes were found in MMP-2, TIMP-1, and -2. The mRNA expression of MMP-9 was low and MMP-13 was not detected. This study suggests that MMP-1 and -3, enhanced by uniaxial cyclic mechanical stimulation of osteoblasts, are candidate key enzymes in the processing of collagen on bone surface, which might be necessary to allow osteoclastic recruitment leading to bone resorption. The strain might also play a role in cleaning of demineralized bone surface during the reversal phase, before bone formation starts.

Are statins associated with decreased tooth loss in chronic periodontitis?

AIM

To evaluate whether statin use was associated with decreased tooth loss among patients with chronic periodontitis.

MATERIAL AND METHODS

We evaluated administrative health plan data from 1996 to 2002 covering dental and periodontal treatment utilization, dental extractions, and prescription medication fills of 12,631 adults aged 48-64 in 2002. With tooth loss as the outcome, we evaluated a number of different patterns of statin prescription across time in multivariate generalized linear models.

RESULTS

Unadjusted, statin use was associated with increased tooth loss. After adjustment for potential confounders, there was no suggestion of either increased or decreased tooth loss associated with statin use.

CONCLUSIONS

Statin use was not associated with either a decreased or an increased risk of tooth loss.