The overexpression of cyclo-oxygenase-2 in chronic periodontitis

Inducing cyclooxygenase-2 expression, prostaglandin E2 and prostaglandin F2α production of human dental pulp cells by activation of toll-like receptor-3, mitogen-activated protein kinase kinase/extracellular signal-regulated kinase and p38 signaling

Background/purpose

Bacterial infection was the major etiology for pulpal/root canal infection. This study aimed to investigate the activation of toll-like receptor-3 (TLR) on cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) and PGF2α production of human dental pulp cells (HDPCs) and associated signaling.

Materials and methods

HDPCs were exposed to different concentrations of Poly (I:C) (a TLR3 activator). Cell viability was determined by 3- (4,5-Dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay and alkaline phosphatase (ALP) activity was evaluated by ALP staining. Activation of extracellular signal-regulated kinase (ERK) and p38 by Poly (I:C) was determined by immunofluorescent staining. The COX-2 protein expression was analyzed by Western blot. PGE2 and PGF2α production was measured by enzyme-linked immunosorbent assay. The mRNA expression was studied by real-time polymerase-chain reaction. Moreover, HDPCs were exposed to Poly(I:C) with/without U0126 or SB203580 treatment and analysis of COX-2 expression and prostanoid production were conducted.

Results

Poly (I:C) showed little effect on ALP activity, but decreased viability of HDPCs. It stimulated COX-2 mRNA and protein expression. Poly (I:C) induced PGE2 and PGF2α production of HDPCs. Poly (I:C) activated p-ERK, and p-p38 protein expression. Treatment by U0126 (a mitogen-activated protein kinase kinase (MEK)/ERK inhibitor) and SB203580 (a p38 inhibitor) attenuated Poly (I:C)-induced COX-2 mRNA and protein expression as well as PGE2 and PGF2α production.

Conclusion

TLR3 activation is involved in the infection and inflammatory responses of pulp tissues, via MEK/ERK, and p38 signaling to mediate COX-2 expression as well as PGE2 and PGF2α production, contributing to the pathogenesis and progression of pulpal/periapical diseases.

Necrotizing Gingivitis: Microbial Diversity and Quantification of Protein Secretion in Necrotizing Gingivitis

Necrotizing gingivitis (NG) is a necrotizing periodontal disease that differs from chronic gingivitis (CG). To date, both the microbiological causes and the involved host cytokine response of NG still remain unclear. Here, we investigated corresponding interdental plaque and serum samples from two groups of Chinese patients with CG (n = 21) or NG (n = 21). The microbiota were studied by 16S rRNA Illumina MiSeq sequencing of the microbial metagenome and by assessing quantitatively the abundance of the phylum Bacteroidetes, the genus Prevotella and the species T. forsythia, P. endodontalis, and P. gingivalis using fluorescence in situ hybridization (FISH). With respect to the associated host response, the levels of 30 inflammatory mediators were quantified by multiplex immunoassay analysis. Differential microbial abundance analysis of the two disease groups revealed at the phylum level that Proteobacteria accounted for 67% of the differentially abundant organisms, followed by organisms of Firmicutes (21%) and Actinobacteria (9%). At the species level, significant differences in abundance were seen for 75 species of which 58 species were significantly more abundant in CG patients. Notably, the FISH analysis revealed that Bacteroidetes was the most prevalent phylum in NG. The multiplex cytokine assay showed significant quantitative differences between the disease groups for eight analytes (GM–CSF, G–CSF, IFN–α, IL–4, IL–13, TNF–α, MIG, and HGF). The G–CSF was found to be the most significantly increased inflammatory protein marker in NG. The next-generation sequencing (NGS) data supported the understanding of NG as a multi-microbial infection with distinct differences to CG in regard to the microbial composition.

Effect of non-steroidal anti-inflammatory drugs on pulpal and periapical inflammation induced by lipopolysaccharide

OBJECTIVES

The objective of this study was to evaluate the effect of non-steroidal anti-inflammatory drugs (NSAIDs) in controlling pulpal and periapical inflammation in vivo as a potential coadjutant systemic therapy for pulpitis.

MATERIALS AND METHODS

A suspension containing E. coli lipopolysaccharide (LPS; 1.0 μg/μL) was inoculated into the pulp chamber of the first molars of C57BL/6 mice (n = 72), and the animals were treated daily with indomethacin or celecoxib throughout the experimental periods. After 7, 14, 21, and 28 days, the tissues were removed for histopathological, histoenzymology, histometric, and immunohistochemical evaluation.

RESULTS

Inoculation of LPS into the pulp chamber induced the synthesis of the enzyme cyclooxygenase-2 (COX-2) in dental pulp and periapical region. Indomethacin and celecoxib treatment changed the profile of inflammatory cells recruited to dental pulp and to the periapex, which was characterized by a higher mononuclear cell infiltrate, compared to LPS inoculation alone which recruited a higher amount of polymorphonuclear neutrophils. Administration of indomethacin for 28 days resulted in the development of apical periodontitis and increased osteoclast recruitment, unlike celecoxib.

CONCLUSIONS

NSAIDs indomethacin and celecoxib changed the recruitment of inflammatory cells to a mononuclear profile upon inoculation of LPS into the pup chamber, but indomethacin enhanced periapical bone loss whereas celecoxib did not.

CLINICAL RELEVANCE

Celecoxib, a selective COX-2 inhibitor, can change the profile of inflammatory cells recruited to the dental pulp challenged with LPS and might a be potential systemic coadjutant for treatment of pulpitis.

Epithelial barrier and oral bacterial infection

The oral epithelial barrier separates the host from the environment and provides the first line of defense against pathogens, exogenous substances and mechanical stress. It consists of underlying connective tissue and a stratified keratinized epithelium with a basement membrane, whose cells undergo terminal differentiation resulting in the formation of a mechanically resistant surface. Gingival keratinocytes are connected by various transmembrane proteins, such as tight junctions, adherens junctions and gap junctions, each of which has a specialized structure and specific functions. Periodontal pathogens are able to induce inflammatory responses that lead to attachment loss and periodontal destruction. A number of studies have demonstrated that the characteristics of pathogenic oral bacteria influence the expression and structural integrity of different cell-cell junctions. Tissue destruction can be mediated by host cells following stimulation with cytokines and bacterial products. Keratinocytes, the main cell type in gingival epithelial tissues, express a variety of proinflammatory cytokines and chemokines, including interleukin-1alpha, interleukin-1beta, interleukin-6, interleukin-8 and tumor necrosis factor-alpha. Furthermore, the inflammatory mediators that may be secreted by oral keratinocytes are vascular endothelial growth factor, prostaglandin E2 , interleukin-1 receptor antagonist and chemokine (C-C motif) ligand 2. The protein family of matrix metalloproteinases is able to degrade all types of extracellular matrix protein, and can process a number of bioactive molecules. Matrix metalloproteinase activities under inflammatory conditions are mostly deregulated and often increased, and those mainly relevant in periodontal disease are matrix metalloproteinases 1, 2, 3, 8, 9, 13 and 24. Viral infection may also influence the epithelial barrier. Studies show that the expression of HIV proteins in the mucosal epithelium is correlated with the disruption of epithelial tight junctions, suggesting a possible enhancement of human papilloma virus infection by HIV-associated disruption of tight junctions. Altered expression of matrix metalloproteinases was demonstrated in keratinocytes transformed with human papilloma virus-16 or papilloma virus-18,. To summarize, the oral epithelium is able to react to a variety of exogenous, possibly noxious influences.

Inflammation-induced Bone Remodeling in Periodontal Disease and the Influence of Post-menopausal Osteoporosis

During physiological conditions, the skeleton is remodeled in so-called bone multi-cellular units. Such units have been estimated to exist at 1–2 x 106 sites in the adult skeleton. The number and activities of these units are regulated by a variety of hormones and cytokines. In post-menopausal osteoporosis, lack of estrogen leads to increased numbers of bone multi-cellular units and to uncoupling of bone formation and bone resorption, resulting in too little bone laid down by osteoblasts compared with the amount of bone resorbed by osteoclasts. Inflammatory processes in the vicinity of the skeleton, e.g., marginal and apical periodontitis, will affect the remodeling of the nearby bone tissue in such a way that, in most patients, the amount of bone resorbed exceeds that being formed, resulting in net bone loss (inflammation-induced osteolysis). In some patients, however, inflammation-induced bone formation exceeds resorption, and a sclerotic lesion will develop. The cellular and molecular pathogenetic mechanisms in inflammation-induced osteolysis and sclerosis are discussed in the present review. The cytokines believed to be involved in inflammation-induced remodeling are very similar to those suggested to play crucial roles in post-menopausal osteoporosis. In patients with periodontal disease and concomitant post-menopausal osteoporosis, the possibility exists that the lack of estrogen influences the activities of bone cells and immune cells in such a way that the progression of alveolar bone loss will be enhanced. In the present paper, the evidence for and against this hypothesis is presented.

Increased cyclooxygenase 2 expression in association with oral lichen planus severity

Background/purpose

Although some studies have shown induction of cyclooxygenase 2 (COX-2) in oral lichen planus (OLP), an association between COX-2 upregulation and OLP clinical severity has not been investigated. Therefore, we aimed to compare COX-2 expression in OLP with that in normal oral tissues, and to determine correlations between COX-2 expression and both clinical criteria and visual analog scale (VAS) scores.

Materials and methods

COX-2 expression was studied in 25 OLP and 13 normal oral tissues by immunohistochemistry. Both clinical criteria and VAS scores were used to evaluate the clinical severity of OLP. The differences in COX-2 expression between OLP and normal tissues, and the correlations between COX-2 expression and clinical severity were determined by the nonparametric statistical tests.

Results

COX-2 expression was significantly increased in OLP epithelium when compared with normal epithelium (P < 0.001), and intense COX-2 staining in inflammatory infiltrates was observed in the OLP lamina propria. COX-2 expression in OLP epithelium and inflammatory infiltrates was significantly correlated with the clinical criteria score (r = 0.428, P = 0.007, and r = 0.681, P < 0.001, respectively), whereas a significant correlation with the VAS score was observed only in OLP inflammatory infiltrates (r = 0.605, P < 0.001).

Conclusion

Enhanced COX-2 expression in both OLP epithelium and inflammatory infiltrates correlates well with the clinical severity. An association between VAS score and COX-2 expression in OLP inflammatory infiltrates suggests an important role of additional COX-2 expression from inflammation in causing pain in OLP patients.

Elevated levels of cyclooxygenase 1 and 2 in human cyclosporine induced gingival overgrowth

OBJECTIVE

This study was carried out to immuno-localize and estimate the levels of cyclooxygenase 1 and 2 in human gingival tissue samples from healthy individuals, chronic periodontitis patients and patients with cyclosporine induced gingival overgrowth.

METHODS

Group I consisted of individuals with healthy gingiva (n=6), Group II - cyclosporine induced gingival overgrowth (n=9) and Group III - chronic periodontitis patients (n=6). Gingival tissue samples were collected from subjects of all the three groups. COX-1, COX-2 levels were estimated in tissue homogenates by enzyme activity assay. Immuno-localization for COX-1 and COX-2 was also done in sections of gingival tissue.

RESULTS

The study results demonstrated a significantly higher mean levels of COX-1 and 2 in drug induced gingival overgrowth samples (p<0.05). COX-1 and COX-2 was localized to epithelium and connective tissue in human gingival tissue sections from cyclosporine induced gingival overgrowth.

CONCLUSION

Cyclooxygenase enzymes appear to be potential mediators involved in the pathogenesis of cyclosporine induced gingival overgrowth.

Candidate biomarkers for cervical cancer treatment: Potential for clinical practice (Review)

Cervical cancer ranks high among the causes of female cancer mortalities and is an important disease in developing and developed countries. Current diagnosis of cervical cancer depends on colposcopy, pathological diagnosis and preoperative diagnosis using methods, including magnetic resonance imaging and computed tomography. Advanced cervical cancer has a poor prognosis. The tumor marker squamous cell carcinoma is conventionally used for screening, but recent studies have revealed the mechanisms of carcinogenesis and the factors associated with a poor prognosis in cervical cancer. These include epigenetic biomarkers, with the methylation level of the checkpoint with forkhead and ring finger gene being potentially useful for predicting the malignancy of cervical cancer and sensitivity to treatment with paclitaxel. The extent of methylation of the Werner DNA helicase gene is also useful for determining sensitivity to an anticancer agent, CPT-11. In addition to epigenetic changes, the expression levels of hypoxia-inducible factor 1α subunit, epidermal growth factor receptor and cyclooxygenase-2 have been reported as possible biomarkers in cervical cancer. Novel prognostic factors, including angiogenic factors, fragile histidine triad, thymidylate synthase, glucose-related protein 58 and mucin antigens, have also been described, and hemoglobin and platelets may also be significant prognostic biomarkers. Utilization of these biomarkers may facilitate personalized treatment and improved outcomes in cervical cancer.

COX-2 gene polymorphisms and risk of chronic periodontitis: a case-control study and meta-analysis

OBJECTIVE

Cyclooxygenase-2 (COX-2) enzyme is a major mediator of inflammation in periodontitis, leading to loss of gingival tissues and alveolar bone supporting the teeth. Previous studies have explored the role of COX-2 polymorphisms with the risk of periodontitis in different ethnic groups; however, findings are inconsistent. So, we aimed to investigate the association of COX-2 polymorphisms (rs20417, rs689466, and rs5275) in susceptibility to chronic periodontitis (CP) in northern Indian population. Meta-analysis was also carried out to precisely estimate the effect of COX-2 polymorphisms in CP.

MATERIALS AND METHODS

Genotyping of COX-2 polymorphisms was carried out through PCR-RFLP in 200 CP cases and 200 controls. For risk estimation, binary logistic regression was applied using SPSS, version 15.0, while meta-analysis was carried using MIX 2.0 software.

RESULTS

None of the COX-2 polymorphisms independently were associated with the risk of CP. Meta-analysis suggested a significant reduced risk of CP with rs5275+8473 C allele and rs20417 in Chinese population.

CONCLUSIONS

No association was observed in any of the studied COX-2 polymorphisms with CP in North India. But, the study should be replicated in larger sample size to arrive at a definitive conclusion. Meta-analysis suggested a role of rs5275 COX-2 polymorphisms in susceptibility to overall CP, and on ethnic basis, rs20417 showed reduced risk of CP in Chinese population.

Thermal stimulation of TRPV1 up-regulates TNFα expression in human periodontal ligament cells

OBJECTIVE

We previously demonstrated that the activation of transient receptor potential vanilloid 1 (TRPV1), a nociceptive ion channel receptor, by capsaicin led to the up-regulation of the osteoprotegerin (OPG)/receptor activator of nuclear factor kappa B ligand (RANKL) ratio in human periodontal ligament (HPDL) cells. Since TRPV1 is recognised as one of the thermo-sensitive cation channels, this study investigated the response of TRPV1 to thermal stimulation in HPDL cells.

METHODS

HPDL cells were incubated at 45°C for thermal stimulation. The mRNA expression of OPG, RANKL, tumour necrosis factor α (TNFα), and interleukin-1 β (IL-1β) was determined by using RT-PCR. OPG secretion and RANKL protein expression were analysed by ELISA and Western blot analysis, respectively. The mechanisms of heat-induced TNFα expression were studied using several TRPV1 inhibitors.

RESULTS

In contrast to capsaicin, thermal stimulation had no effect on OPG or RANKL expression. Interestingly, the mRNA expression of TNFα, but not IL-1β, was increased by heat. Using TRPV1 antagonists, we confirmed that TNFα up-regulation was mediated by TRPV1. Phospholipase C (PLC) was previously shown to be involved in capsaicin-induced OPG expression. However, we found that protein kinase C, not PLC, was required for heat-induced TNFα expression. Additionally, the use of cytochalasin D, an inhibitor of actin polymerisation, revealed that cytoskeleton rearrangement might be an important mechanism for cellular sensing of thermal stimuli.

CONCLUSION

Our results indicate that TRPV1 plays a multi-functional role in HPDL cells depending on the stimuli. In response to heat, TRPV1 activation leads to the induction of TNFα expression.

Cyclooxygenase-2 expression in gingival biopsies from periodontal patients is correlated with connective tissue loss

BACKGROUND

The objective of this study is to compare cyclooxygenase-2 (COX-2) protein expression in gingival biopsies from patients with chronic periodontitis (CP), patients with gingivitis (GV), and individuals with no periodontal disease (control group) and to establish its relationship with clinical variables and connective tissue loss in the lamina propria.

METHODS

A cross-sectional and analytic study was conducted in 108 gingival biopsies from 52 patients with CP, 39 with GV, and 17 controls. All biopsies were processed for conventional histopathologic study, immunohistochemical determination of COX-2 protein expression, and automatic quantification of connective tissue by image analysis.

RESULTS

The protein expression of COX-2, mainly produced by plasma cells and monocytes, was significantly related to the presence of periodontal disease, bleeding index, intensity of inflammatory infiltrate, and loss of connective tissue in the lamina propria of gingival biopsies (P <0.01, Spearman test). COX-2 expression was also directly correlated with attachment loss (P <0.05, Spearman test).

CONCLUSIONS

COX-2 protein expression is higher in patients with GV and CP than in individuals without periodontal disease and is inversely correlated with the amount of connective tissue in the lamina propria as determined by image analysis. This finding suggests that COX-2 participates in mechanisms and pathway signaling related to the destruction of fibrillar support structures of the periodontium.

Expression of prostaglandin E synthases in periodontitis immunolocalization and cellular regulation

The inflammatory mediator prostaglandin E(2) (PGE(2)) is implicated in the pathogenesis of chronic inflammatory diseases including periodontitis; it is synthesized by cyclooxygenases (COX) and the prostaglandin E synthases mPGES-1, mPGES-2, and cPGES. The distribution of PGES in gingival tissue of patients with periodontitis and the contribution of these enzymes to inflammation-induced PGE(2) synthesis in different cell types was investigated. In gingival biopsies, positive staining for PGES was observed in fibroblasts and endothelial, smooth muscle, epithelial, and immune cells. To further explore the contribution of PGES to inflammation-induced PGE(2) production, in vitro cell culture experiments were performed using fibroblasts and endothelial, smooth muscle, and mast cells. All cell types expressed PGES and COX-2, resulting in basal levels of PGE(2) synthesis. In response to tumor necrosis factor (TNF-α), IL-1β, and cocultured lymphocytes, however, mPGES-1 and COX-2 protein expression increased in fibroblasts and smooth muscle cells, accompanied by increased PGE(2), whereas mPGES-2 and cPGES were unaffected. In endothelial cells, TNF-α increased PGE(2) production only via COX-2 expression, whereas in mast cells the cytokines did not affect PGE(2) enzyme expression or PGE(2) production. Furthermore, PGE(2) production was diminished in gingival fibroblasts derived from mPGES-1 knockout mice, compared with wild-type fibroblasts. These results suggest that fibroblasts and smooth muscle cells are important sources of mPGES-1, which may contribute to increased PGE(2) production in the inflammatory condition periodontitis.

Human beta-defensin-3 up-regulates cyclooxygenase-2 expression and prostaglandin E2 synthesis in human gingival fibroblasts

BACKGROUND AND OBJECTIVE

Oral epithelial cells express three antimicrobial peptide human beta-defensins (hBDs) that have previously been demonstrated to exert proinflammatory effects on various immune cells. We wanted to examine whether hBDs could induce cyclooxygenase-2 (COX-2) expression and prostaglandin E(2) (PGE(2)) synthesis in non-immune cells, such as human gingival fibroblasts.

MATERIAL AND METHODS

Cultured fibroblasts were treated with different concentrations of hBD-1, -2, -3 or interleukin-1 beta, as a positive control, for various times, in the presence or absence of NS-398, a specific COX-2 inhibitor. The levels of COX-1 and COX-2 mRNA expression were analyzed using RT-PCR and real-time PCR. Whole cell lysates were analyzed for COX-1 and COX-2 protein expression by western blotting. Cell-free culture supernatants were assayed for PGE(2) levels by ELISA. The lactate dehydrogenase assay was performed to determine the cytotoxicity of hBDs.

RESULTS

Ten and 40 microg/mL of hBD-3 up-regulated COX-2 mRNA and protein expression, consistent with COX-2 up-regulation by interleukin-1 beta, whereas hBD-1 and hBD-2 did not. However, COX-1 mRNA and protein were constitutively expressed. The time-course study revealed that hBD-3 up-regulated COX-2 mRNA and protein expression at 6 and 12 h, respectively. Consistent with COX-2 up-regulation, 10 and 40 microg/mL of hBD-3 significantly increased PGE(2) levels in cell-free culture supernatants (p < 0.05), and this was inhibited by NS-398 in a dose-dependent manner. Neither of the hBD concentrations tested in this study was toxic to the cells.

CONCLUSION

These findings indicate that epithelial human beta-defensin-3 functions as a proinflammatory mediator in controlling arachidonic acid metabolism in underlying fibroblasts.

Porphyromonas gingivalis may play an important role in the pathogenesis of periodontitis-associated rheumatoid arthritis

Rheumatoid arthritis (RA) is a common, systemic autoimmune disease which leads to destruction of the joint architecture and consequent disability. Although the aetiology of RA remains unknown, accumulating studies have established a strong association between RA and periodontitis (PD). Recently, anti-cyclic citrullinated peptide (anti-CCP) autoantibody and citrullinated peptide have been realized to be involved in the breaking of self-tolerance and development of autoimmune in RA. The citrullinated peptide is generated by post-translational modification (citrullination) of protein-bound arginine by peptidylarginine deiminase (PAD). Porphyromonas gingivalis(P. gingivalis), the major aetiological agent of PD and the only bacterium known to express a PAD enzyme, has been reported to be significantly associated with RA. The antibody titers to P. gingivalis are significantly increased in patients with RA and P. gingivalis antibody titers are significantly correlated with anti-CCP antibody isotypes that are specific to RA. Recent study indicates that the major synovial targets of the RA-specific anti-CCP autoantibodies are deiminated forms of the alpha- and beta- chains of fibrin. Meanwhile, it is also confirmed that bacterial PAD produced by P. gingivalis has the capacity of deiminating arginine in fibrin found in the periodontal lesion. What's more, it has been demonstrated that citrullination of HLA binding peptide causes a 100-fold increase in peptide-MHC affinity and leads to the activation CD4(+)T cells in HLA DRB1 0401 transgenic mice. Therefore, we postulate that P. gingivalis may play a crucial role in the pathogenesis of periodontitis-associated RA. P. gingivalis, which colonizes in the oral cavity, produces PAD enzyme continuously that leads to the citrullination of RA autoantigen such as fibrin in synovium joint. These PAD engendered antigens, presented in association with major histocompatibility complex (MHC) molecules by antigen-presenting cells (APC), ultimately lead to production of the anti-CCP antibody. The anti-CCP antibodies form immune complexes with citrullinated proteins, which can be bound by inflammatory cells via their Fc receptors. The roles of these immune complexes and inflammatory cells are mediated by a complex cascade involving complement activation. These mechanisms result in a release of mediators of inflammation and joint destruction ultimately leading to the onset of RA. This hypothesis reveals that oral bacterial infection may play a role in peptide citrullination which might be involved in loss of self-tolerance and development of autoimmune in RA.

Local and systemic responses in matrix metalloproteinase 8-deficient mice during Porphyromonas gingivalis-induced periodontitis

Periodontitis is a bacterium-induced chronic inflammation that destroys tissues that attach teeth to jaw bone. Pathologically excessive matrix metalloproteinase 8 (MMP-8) is among the key players in periodontal destruction by initiating type I collagen degradation. We studied MMP-8 in Porphyromonas gingivalis-induced periodontitis by using MMP-8-deficient (MMP8(-/-)) and wild-type (WT) mice. Alveolar bone loss, inflammatory mediator expression, serum immunoglobulin, and lipoprotein responses were investigated to clarify the role of MMP-8 in periodontitis and systemic inflammatory responses. P. gingivalis infection induced accelerated site-specific alveolar bone loss in both MMP8(-/-) and WT mice relative to uninfected mice. The most extensive bone degradation took place in the P. gingivalis-infected MMP8(-/-) group. Surprisingly, MMP-8 significantly attenuated (P < 0.05) P. gingivalis-induced site-specific alveolar bone loss. Increased alveolar bone loss in P. gingivalis-infected MMP8(-/-) and WT mice was associated with increase in gingival neutrophil elastase production. Serum lipoprotein analysis demonstrated changes in the distribution of high-density lipoprotein (HDL) and very-low-density lipoprotein (VLDL) particles; unlike the WT mice, the MMP8(-/-) mice underwent a shift toward a smaller HDL/VLDL particle sizes. P. gingivalis infection increased the HDL/VLDL particle size in the MMP8(-/-) mice, which is an indicator of lipoprotein responses during systemic inflammation. Serum total lipopolysaccharide activity and the immunoglobulin G-class antibody level in response to P. gingivalis were significantly elevated in both infected mice groups. Thus, MMP-8 appears to act in a protective manner inhibiting the development of bacterium-induced periodontal tissue destruction, possibly through the processing anti-inflammatory cytokines and chemokines. Bacterium-induced periodontitis, especially in MMP8(-/-) mice, is associated with systemic inflammatory and lipoprotein changes that are likely involved in early atherosclerosis.

N-3 polyunsaturated fatty acid effect in periodontal disease: state of art and possible mechanisms involved

Anti-inflammatory properties have been widely reported for n-3 polyunsaturated fatty acids (PUFAs) and some studies have been focalized on their possible role in the modulation of gingivitis and alveolar bone resorption in periodontal disease (PD). Increased formation of arachidonic acid-derived inflammatory eicosanoids and augmented oxidative stress are two molecular mechanisms pathogenetically involved in the progression of PD and known to be inhibited by n-3 PUFAs in PD setting. The present review will focus also on other molecular pathways and factors known to be altered in the development of PD and known to be subject to n-3 PUFA modulation in other pathological settings different from PD. Overall, the available findings strongly encourage further experimental studies on animals subject to experimental PD and treated with n-3 PUFAs, long term n-3 PUFA intervention studies on PD patients and molecular studies to identify additional potential molecular routes of n-3 PUFA action in PD.

Omega-3 fatty acid regulates inflammatory cytokine/mediator messenger RNA expression in Porphyromonas gingivalis-induced experimental periodontal disease

INTRODUCTION

Porphyromonas gingivalis is strongly implicated in the etiology of adult periodontitis by inducing inflammatory cytokines, resulting in gingival and periodontal tissue inflammation and alveolar bone resorption. This study tested the hypothesis that supplementing the diet with omega-3 fatty acid (omega-3 FA; i.e. fish oil) would exert anti-inflammatory effects in the gingival tissues of P. gingivalis-infected rats.

METHODS

Rats were fed either fish oil or corn oil diets ad libitum for 22 weeks and infected with P. gingivalis strain 381 or strain A7A1-28. After sacrifice, rat gingival tissues were excised and the RNA was isolated and analyzed for proinflammatory mediators [interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), IL-6], T helper type 1 and type 2 cytokines [interferon-gamma (IFN-gamma), IL-4, IL-10), antioxidant enzymes [catalase (CAT), superoxide dismutase (SOD)], and genes critical for eicosanoid mediator production [cyclo-oxygenase-2 (COX-2), 5-lipoxygenase (5-LO)] by reverse transcription-polymerase chain reaction using rat-specific primers.

RESULTS

Rats on the omega-3 FA diet exhibited decreased proinflammatory cytokine gene expression (IL-1beta, TNF-alpha) and enhanced IFN-gamma, CAT and SOD messenger RNA expression compared to rats fed a corn oil diet, supporting a diet-induced modulation of host inflammatory reactions. Analyses of alveolar bone resorption in the rats related to gene expression profiles demonstrated significant positive correlations with IL-1beta, IL-6 and COX-2 and negative correlations with CAT and SOD.

CONCLUSION

These findings suggest that diets enriched for omega-3 FA modulate the local gingival inflammatory milieu of the host following oral P. gingivalis infection, which impacts on alveolar bone resorption in rats.

Quantitative HPLC-UV method for the determination of firocoxib from horse and dog plasma

A sensitive reversed-phase HPLC-UV method was developed for the determination of firocoxib, a novel and highly selective COX-2 inhibitor, in plasma. A 1.0 mL dog or horse plasma sample is mixed with water and passed through a hydrophobic-lipophilic copolymer solid-phase extraction column to isolate firocoxib. Quantitation is based on an external standard curve. The method has a validated limit of quantitation of 25 ng/mL and a limit of detection of 10 ng/mL. The validated upper limit of quantitation was 2500 ng/mL for horses and 10,000 ng/mL for dogs. The average recoveries ranged from 88-93% for horse plasma and 96-103% for dog plasma. The coefficient of variation in all cases was less than 10%. This method is suitable for the analysis of clinical samples from pharmacokinetic and bioequivalence studies and drug monitoring.

Pharmacokinetics and metabolism of orally administered firocoxib, a novel second generation coxib, in horses

The primary objective of this study was to determine the pharmacokinetic profile of firocoxib, a novel second generation coxib, in horses. Horses were administered either a single oral or intravenous dose of firocoxib at 0.1 mg/kg in a two-period crossover study with 12 animals. The dosage was based on previously determined pharmacodynamic parameters. Oral firocoxib was well absorbed with an average bioavailability (absolute) of 79% and a Cmax of 75 ng/mL at 3.9 h. The average elimination half-life was 30 h. Following intravenous administration the average Cmax was 210 ng/mL and the elimination half-life was 34 h. The area under the curve [AUC(0-tlast)] was 1.8 microg.h/mL for the oral dose and 2.3 microg.h/mL for the intravenous dose. Firocoxib was widely distributed with a volume of distribution value of 1.7 L/kg for the intravenous dose. Biotransformation of firocoxib was via dealkylation and glucuronidation to inactive metabolites, namely descyclopropylmethylfirocoxib and its glucuronide conjugate. Urinary excretion was the major route of elimination, and the clearance rate was 37 mL/h/kg.

Effects of selective cyclooxygenase-2 inhibitor and omega-3 fatty acid on serum interleukin-1beta, osteocalcin, and C-reactive protein levels in rats

BACKGROUND

The aim of this study was to evaluate the effects of selective cyclooxygenase-2 inhibitor, celecoxib, and omega-3 fatty acid on serum levels of interleukin 1-beta (IL-1beta), osteocalcin (OC), and C-reactive protein (CRP) in experimental periodontitis.

METHODS

Experimental periodontitis in rats was induced by repeated injection of purified lipopolysaccharide (LPS) derived from Escherichia coli endotoxin. Forty-seven adult male Sprague-Dawley rats were divided into five study groups as follows: saline control, LPS, LPS + celecoxib, LPS + omega-3 fatty acid, and LPS + celecoxib + omega-3 fatty acid. Celecoxib and omega-3 fatty acid were given alone or in combination during 14 days of the experimental study period. At the end of the 2-week protocol, serum samples were obtained, and the rats were sacrificed. Serum samples were analyzed for IL-1beta, OC, and CRP concentrations by enzyme-linked immunosorbent assay. Defleshed jaws were analyzed morphometrically for alveolar bone loss. Data were evaluated statistically by non-parametric tests.

RESULTS

According to the morphometric measurements, the LPS and drug treatment groups showed significantly higher bone loss than the saline control group (P <0.05). Omega-3 fatty acid, both alone and in combination with celecoxib, revealed significantly higher IL-1beta levels than LPS and celecoxib groups (P <0.05). Individual and combined administration of celecoxib and omega-3 fatty acid significantly increased OC levels compared to the LPS group (P <0.05). There were no significant differences in serum CRP levels.

CONCLUSIONS

Celecoxib and/or omega-3 fatty acid administration does not significantly influence circulating levels of CRP. The significantly increased serum OC level observed after individual and combination administration suggests that celecoxib and omega-3 fatty acid may influence bone remodeling and thereby inhibit the progression of alveolar bone resorption. However, the failure to observe any significant inhibition of bone loss in celecoxib- and/or omega-3 fatty acid-treated rats compared to the LPS group suggests that their therapeutic effect may be reduced by other factors, such as increases in serum IL-1beta promoting osteoclast activity.

Hypothesis: the humoral immune response to oral bacteria provides a stimulus for the development of rheumatoid arthritis

Rheumatoid arthritis (RA) and adult periodontitis share common pathogenetic mechanisms and immunologic and pathological findings. One oral pathogen strongly implicated in the pathogenesis of periodontal disease, Porphyromonas gingivalis, possesses a unique microbial enzyme, peptidylarginine deiminase (PAD), the human equivalent of which has been identified as a susceptibility factor for RA. We suggest that individuals predisposed to periodontal infection are exposed to antigens generated by PAD, with de-iminated fibrin as a likely candidate, which become systemic immunogens and lead to intraarticular inflammation. PAD engendered antigens lead to production of rheumatoid factor-containing immune complexes and provoke local inflammation, both in gingiva and synovium via Fc and C5a receptors.

In vitro studies of a degradable device for controlled-release of meloxicam

BACKGROUND

Plaque biofilm and associated host responses are the primary factors in the pathogenesis of periodontitis. Delivery of medications directly into the periodontal pockets to suppress or eradicate the pathogenic microbiota or modulate the inflammatory response has attracted significant interest to limit periodontal tissue destruction. The aim of the present study was twofold: (1) to describe the development of a biodegradable controlled-release device containing meloxicam as the therapeutic agent and (2) to evaluate the in vitro release of meloxicam from this device into different release media.

METHODS

Films of cross-linked gelatin matrix containing meloxicam were prepared, hardened for various time periods and cut in a form to fit to the periodontal pocket anatomy. The release of active agents was studied separately in 10 ml distilled water, artificial saliva and pH 7.4 phosphate buffer at 37 degrees C. Apparatus Vibrax was used at 120 r.p.m. Determinations were carried out spectrophotometrically, and the release profiles were plotted as a function of time. The results were evaluated by the similarity test.

RESULTS

The release rates of meloxicam from the hardened (1 h, 4 h, 8 h) formulations were slower than the unhardened formulation in all the three release media. Increasing the hardening time decreased the release rates. The overall release rates were similar in artificial saliva and pH 7.4 phosphate buffer, while it was lower in distilled water.

CONCLUSIONS

As a conclusion, cross-linked gelatin matrix films may be considered as a suitable inert material for obtaining a prolonged local release of meloxicam as an adjunct to the mechanical periodontal treatment. As required, further in vitro and in vivo studies will be performed before starting clinical applications of this controlled-release formulation of the anti-inflammatory agent.

Individual and combined effects of selective cyclooxygenase-2 inhibitor and omega-3 fatty acid on endotoxin-induced periodontitis in rats

BACKGROUND

The present study was planned to evaluate the individual and combined effects of selective cyclooxygenase-2 (COX-2) inhibitor, celecoxib, and omega-3 fatty acid on the gingival tissue levels of prostaglandin E2 (PGE2), prostaglandin F2alpha (PGF2alpha), leukotriene B4 (LTB4), and platelet activating factor (PAF) in endotoxin-induced periodontitis in rats.

METHODS

Experimental periodontitis was induced by repeated injection of Escherichia coli endotoxin (LPS). Forty-four adult male Sprague-Dawley rats were divided into five study groups: saline control, LPS, celecoxib, omega-3 fatty acid, and combination celecoxib and omega-3 fatty acid. Celecoxib and omega-3 fatty acid were given either as a single agent or as a combination therapy during 14 days of the study period. At the end of the 2-week protocol, the rats were sacrificed, the gingival tissues were dissected and extracted, and the extracts were analyzed for PGE2, PGF2alpha, and LTB4 levels by enzyme immunoassay and for PAF levels by radioimmunoassay. The defleshed jaws were analyzed morphometrically for alveolar bone loss. Data were evaluated statistically by using parametric tests.

RESULTS

LPS injection resulted in significantly more bone loss than the saline controls (P<0.05) and significant elevations in the gingival tissue levels of all the analyzed mediators except PGF2alpha. Individual administration of celecoxib revealed significant reductions in PGE2 and PAF levels (P <0.05), while omega-3 fatty acid provided significant reduction in PGE2, PGF2alpha, and LTB4 levels compared to the LPS group (P <0.05). Combined administration of celecoxib and omega-3 fatty acid exhibited significantly lower values than those of the LPS group in all the analyzed membrane phospholipid mediators (P <0.05), which approximated the levels in the saline control group (P>0.05).

CONCLUSIONS

The results of the present study indicate that celecoxib and omega-3 fatty acid, when used individually, show a rather partial effect on the control of the analyzed mediators, but when combined they show a synergic effect and provide significant reductions in the gingival tissue levels of PGE2, PGF2alpha, LTB4, and PAF in LPS-induced experimental periodontitis. These findings may pioneer further clinical human studies investigating the possible place of celecoxib and omega-3 fatty acid in periodontal treatment.

In vitro studies on controlled-release cellulose acetate films for local delivery of chlorhexidine, indomethacin, and meloxicam

BACKGROUND

Delivery of medications into periodontal pockets to suppress or eradicate the pathogenic microbiota or modulate the inflammatory response, thereby limiting periodontal tissue destruction, has attracted significant interest with the purpose of effective periodontal treatment. However, no study has previously attempted to develop a controlled-release formulation of anti-inflammatory agents to be used in the field of periodontology. The aim of the present study was to examine the in vitro release profile of chlorhexidine gluconate, indomethacin, and meloxicam from cellulose acetate films.

METHODS

Cellulose acetate films containing chlorhexidine gluconate, indomethacin, and meloxicam were prepared and cut in a form to fit to the periodontal pocket anatomy. The release of active agents was studied in 10 ml artificial saliva at 37 degrees C. Apparatus Vibrax was used at 150 r.p.m. Determinations were carried out spectrophotometrically and the release profiles were plotted as a function of time.

RESULTS

The formulations showed two different release patterns for a total observation period of approximately 120 h. When the formulations of the three active agents were compared, the release patterns of meloxicam and chlorhexidine gluconate were found to be similar, while the indomethacin-containing formulation exhibited the fastest release rate.

CONCLUSIONS

As a conclusion, cellulose acetate may be a suitable inert material for obtaining a prolonged local release of various anti-inflammatory agents like meloxicam. Further in vitro and in vivo studies are required before starting clinical applications of these controlled-release formulations of anti-inflammatory agents.