Differential regulation of interleukin-6 and inducible cyclooxygenase gene expression by cytokines through prostaglandin-dependent and -independent mechanisms in human dental pulp fibroblasts

Icariin negatively regulated lipopolysaccharide-induced inflammation and ameliorated the odontogenic activity of human dental pulp cells in vitro

Alleviating inflammation and promoting dentine regeneration is critical for the healing of pulpitis. In this study, we investigated the anti-inflammatory, angiogenesis and odontogenesis function of icariin on Human dental pulp cells (HDPCs) under inflammatory state. Furthermore, the underlying mechanisms was also evaluated. Icariin attenuated the LPS-induced pro-inflammatory marker expression, such as interleukin-1β (IL-1β), IL-6 and IL-8. The immunoblotting and immunofluorescence staining results showed that icariin suppressed the inflammatory responses mediated by the protein kinase B (Akt) and nuclear factor kappa-B (NF-κB) signaling cascades. Additionally, icariin also upregulated the expression of odontogenic and angiogenic genes and proteins (namely dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), anti-collagen Ⅰ (COL-Ⅰ), and vascular endothelial growth factor (VEGF) and fibroblast growth factor-1 (FGF-1)), alkaline phosphatase activity, and calcium nodule deposition in LPS-exposed HDPCs. In a word, our findings indicated that icariin attenuated pulp inflammation and promoted odontogenic and angiogenic differentiation in the inflammatory state. Icariin may be a promising vital pulp therapy agent for the regenerative treatment of the inflamed dental pulp.

Evaluation of the in vitro and in vivo anti-inflammatory activity of Gymnosporia montana (Roth). Benth leaves

ETHNO-PHARMACOLOGICAL RELEVANCE

Gymnosporia montana (Roth) Benth an herbaceous shrub used in Indian traditional medicine their leaves decoction was used as mouthwash to get relieve from toothache, hence it is also known as Dantakashta in Sanskrit language which means the plant used for tooth problems. Traditionally the leaves juice used to alleviate inflammation and in some parts of India like Saurashtra in Gujarat, leaves were chewed as a folklore cure for Jaundice and in Bhandra region Karnataka, leaves extract mixed with cow milk used for jaundice. Hepatoprotective activity for G. montana leaves was well reported however, its use for inflammation and toothache are still not studied to investigate active phytoconstituents responsible for anti-inflammatory activity.

AIM OF THE STUDY

The present study aimed at bioactivity guided isolation of G. montana leaves extracts using inhibition of pro-inflammatory mediators such as nitric oxide (NO), tumor necrosis factor (TNF-α), and interleukins (IL-1β and IL-6) in RAW 264.7 cells in vitro assay to yield bioactive phytoconstituents.

MATERIALS AND METHODS

The n-hexane, ethyl acetate and methanol extracts prepared from G. montana leaves were evaluated for cell viability using MTT assay. The effect of extracts to inhibit the pro-inflammatory mediators like NO, TNF-α, IL-1β and IL-6 in RAW 264.7 macrophages was measured by enzyme-linked immunosorbent assay (ELISA). The quantitative analysis of the isolated phytoconstituents was performed using quantitative Nuclear Magnetic Resonance (qNMR).

RESULTS

The n-hexane, ethyl acetate, and methanol extracts of G. montana leaves exhibited cell viability in the range of 97.43-84.88% at 50 μg/mL concentration in RAW 264.7 macrophages. In-vitro evaluation of extracts showed that n-hexane extract was most effective in inhibiting NO, TNF-α, IL-1β and IL-6 inflammatory mediators at 50 μg/mL in lipopolysaccharides (LPS) stimulated RAW 264.7 cells. Further n-hexane extract, its fraction GMHA3 and β-amyrin exhibited significant anti-inflammatory activity at 100, 50 and 30 mg/kg per oral, respectively in carrageenan-induced rat paw edema. The quantitative analysis by qNMR revealed β-amyrin as a major compound in the n-hexane extract.

CONCLUSIONS

In vitro and in vivo bioassay results suggested that G. montana n-hexane extract, its fraction GMHA3 and β-amyrin exhibits significant anti-inflammatory activity proves the traditional uses of G. montana leaves. The reported activity of β-amyrin for periodontitis provides evidence of profound the use of G. montana leaves for toothache and anti-inflammatory activity.

The clinical significance of intrapulpal anesthesia for painless dental procedure

Introduction:The elimination of odontalgia and all other forms of oral pain that occurs on dental tissues during dental interventions is still one of the main goals in the dental profession. Aim: The aim of this paper wasto perform an analysis of the literature data on the use of supplementary intrapulpal anesthesia in clinical dental practice. Material and methods: Literature data on the use of intrapulpal anesthesia, the characteristics of this technique of supplementary anesthesia as well as the results of its application were collected. Various databases were used for this purpose, digital data from Google Scholar, Medline, Science-Direct, as well as traditional libraries with manuscripts in printed form were most often taken. Conclusion: The use of supplementary intrapulpal anesthesia in dental/endodontic practice represents a practical and successful type of local anesthesia, when standard mandibular anesthesia for the lower alveolar nerve does not provide a deep enough periinterventional analgesia for dental procedures.

Betamethasone suppresses the inflammatory response in LPS-stimulated dental pulp cells through inhibition of NF-κB

OBJECTIVE

This study aimed to investigate the anti-inflammatory effect of betamethasone on LPS-stimulated human dental pulp stem cells (DPSCs) and its associated mechanism. The osteo-/odontogenic differentiation and osteoclast effect of betamethasone on DPSCs and stem cells from human exfoliated deciduous teeth (SHED) were evaluated.

DESIGN

The proliferative effect of betamethasone on DPSCs was analyzed using a cholecystokinin octapeptide assay. The anti-inflammatory effect of betamethasone was investigated using quantitative polymerase chain reaction (qPCR) and ELISA. The anti-inflammatory mechanism was explored using qPCR, Western blot, and immunofluorescence staining. The osteo-/odontogenic differentiation and osteoclast effect of betamethasone on DPSCs and SHED were detected by qPCR.

RESULTS

1 μg L^-1 betamethasone was found to have the strongest effect on DPSCs proliferation. The expression of pro-inflammatory cytokines and mediators, as well as prostaglandin E₂ (PGE₂) were significantly decreased following treatment with betamethasone in LPS- stimulated DPSCs. They were also decreased in response to an NF-κB inhibitor, Bay 11-7082. Betamethasone and Bay 11-7082 significantly inhibited the expression of p-p65 and promoted the nuclear exclusion of p65. Gene expression associated with osteo-/odontogenic differentiation was significantly up-regulated in betamethasone and osteogenic media (OM) treated groups. The ratio of the receptor activator of nuclear factor kappa B ligand (RANKL) and osteoprotegerin (OPG) at the mRNA level was suppressed in DPSCs and elevated in SHED.

CONCLUSIONS

Betamethasone has an anti-inflammatory effect on LPS- stimulated DPSCs through a blockade of NF-κB activation and exhibits an osteo-/odonto-inductive effect on DPSCs and SHED. Although betamethasone displays an osteoclast effect on SHED.

Dental pulp cells promote the expression of receptor activator of nuclear factor-κB ligand, prostaglandin E2 and substance P in mechanically stressed periodontal ligament cells

OBJECTIVE

This study investigated the expression of receptor activator of nuclear factor-κB ligand (RANKL) in periodontal ligament (PDL) cells co-cultured with dental pulp (DP) cells following mechanical stress in vitro. Furthermore, the expression of prostaglandin (PG) E₂ and substance P (SP) by the PDL cells and by the DP cells were also examined.

DESIGN

PDL and DP cells were obtained from 10 rats. The experimental group consisted of PDL cells subjected to centrifugal force as mechanical stress and co-cultured with DP cells. The 3 control groups of PDL cells were: 1) PDL cells without mechanical stress, 2) PDL cells treated with mechanical stress and 3) PDL cells co-cultured with DP cells. The 2 control groups of DP cells were: 1) DP cells without mechanical stress and 2) DP cells co-cultured with PDL cells. In each group, both cells were examined at day 1 and day 3, and mRNA levels of RANKL by PDL cells were analyzed using Real time quantitative Reverse Transcription (RT)-PCR. Furthermore, RANKL expression was observed using Immunofluorescence staining. PGE₂ and SP expression levels by PDL cells and DP cells were characterized by ELISA analysis.

RESULTS

The expression of RANKL by PDL cells under mechanical stress increased by co-culture with DP cells. PGE₂ and SP expressions were increased in the group of PDL cells subjected to mechanical stress and co-cultured with DP cells.

CONCLUSION

DP cells may facilitate the expression of RANKL in PDL cells under mechanical stress via PGE₂ and SP.

Prostaglandin E2 Stimulates EP2, Adenylate Cyclase, Phospholipase C, and Intracellular Calcium Release to Mediate Cyclic Adenosine Monophosphate Production in Dental Pulp Cells

INTRODUCTION

Prostaglandin E2 (PGE2) plays a crucial role in pulpal inflammation and repair. However, its induction of signal transduction pathways is not clear but is crucial for future control of pulpal inflammation.

METHODS

Primary dental pulp cells were exposed to PGE2 and 19R-OH PGE2 (EP2 agonist) or sulprostone (EP1/EP3 agonist) for 5 to 40 minutes. Cellular cyclic adenosine monophosphate (cAMP) levels were measured using the enzyme-linked immunosorbent assay. In some experiments, cells were pretreated with SQ22536 (adenylate cyclase inhibitor), H89 (protein kinase A inhibitor), dorsomorphin (adenosine monophosphate-activated protein kinase inhibitor), U73122 (phospholipase C inhibitor), thapsigargin (inhibitor of intracellular calcium release), W7 (calmodulin antagonist), verapamil (L-type calcium channel blocker), and EGTA (extracellular calcium chelator) for 20 minutes before the addition of PGE2.

RESULTS

PGE2 and 19R-OH PGE2 (EP2 agonist) stimulated cAMP production, whereas sulprostone (EP1/EP3 agonist) shows little effect. PGE2-induced cAMP production was attenuated by SQ22536 and U73122 but not H89 and dorsomorphin. Intriguingly, thapsigargin and W7 prevented PGE2-induced cAMP production, but verapamil and EGTA showed little effect.

CONCLUSIONS

These results indicate that PGE2-induced cAMP production is associated with EP2 receptor and adenylate cyclase activation. These events are mediated by phospholipase C, intracellular calcium release, and calcium-calmodulin signaling. These results are helpful for understanding the role of PGE2 in pulpal inflammation and repair and possible future drug intervention.

An insight into neurophysiology of pulpal pain: facts and hypotheses

Pain and pain control are important to the dental profession because the general perception of the public is that dental treatment and pain go hand in hand. Successful dental treatment requires that the source of pain be detected. If the origin of pain is not found, inappropriate dental care and, ultimately, extraction may result. Pain experienced before, during, or after endodontic therapy is a serious concern to both patients and endodontists, and the variability of discomfort presents a challenge in terms of diagnostic methods, endodontic therapy, and endodontic knowledge. This review will help clinicians understand the basic neurophysiology of pulpal pain and other painful conditions of the dental pulp that are not well understood.

Short-term acetaminophen consumption enhances the exercise-induced increase in Achilles peritendinous IL-6 in humans

Through an unknown mechanism, the cyclooxygenase inhibitor and antipyretic acetaminophen (APAP) alters tendon mechanical properties in humans when consumed during exercise. Interleukin-6 (IL-6) is produced by tendon during exercise and is a potent stimulator of collagen synthesis. In nontendon tissue, IL-6 is upregulated in the presence of cyclooxygenase inhibitors and may contribute to alterations in extracellular matrix turnover, possibly due to inhibition of prostaglandin E2 (PGE2). We evaluated the effects of APAP on IL-6 and PGE2 in human Achilles peritendinous tissue after 1 h of treadmill exercise. Subjects were randomly assigned to a placebo (n = 8, 26 ± 1 yr) or APAP (n = 8, 25 ± 1 yr) group. Each subject completed a nonexercise and exercise experiment consisting of 6 h of microdialysis. Drug (APAP, 1,000 mg) or placebo was administered in a double-blind manner during both experiments. PGE2 and IL-6 were determined via enzyme immunoassay and APAP via high-performance liquid chromatography. In subjects given APAP, peritendinous APAP levels increased to 4.08 ± 0.65 μg/ml (P < 0.05). PGE2 did not increase with exercise in either group (P > 0.05), nor was PGE2 significantly reduced in the APAP group. IL-6 levels increased with exercise in both groups (P < 0.05), but this increase was greater in the APAP group (P < 0.05). Our findings suggest that APAP enhances tendon IL-6 production after exercise. Peak levels of APAP obtained in the peritendinous space were twofold lower than values reported in plasma or skeletal muscle. These findings provide insight into the effects of APAP on tendon and provide novel information on the kinetics of APAP in tendon tissue after oral APAP consumption.

The latex obtained from Hancornia speciosa Gomes possesses anti-inflammatory activity

AIM OF THE STUDY

Hancornia speciosa Gomes (Apocynaceae) is a tree that is widely distributed throughout Brazil. Its latex is collected and used extensively to treat acne, warts, diseases related to bursitis, and inflammation. In this work, we describe the anti-inflammatory effects of the latex.

MATERIALS AND METHODS

The latex from Hancornia speciosa (0.06-1.3mg/kg, p.o.) and the reference drug acetylsalicylic acid (ASA, 200mg/kg, p.o.) were evaluated in analgesia (formalin-induced licking, acetic acid-induced contortions, and hot plate) and inflammation models (formalin-induced licking, paw oedema, and subcutaneous air pouch, with measurement of cell migration, exudate volume, protein extravasations, nitric oxide, prostaglandin E2, TNF-α, and IL-6, and expression of the enzymes inducible nitric oxide synthase and cyclooxygenase 2).

RESULTS

The latex from Hancornia speciosa significantly inhibited the number of writhings and the time that the animal spent licking the formalin-injected paw (second phase). Doses of 0.1-1.3mg/kg latex reduced carrageenan-induced rat paw oedema. However, only the highest doses (0.6 and/or 1.3mg/kg) reduced the oedema induced by bradykinin, histamine, and serotonin. The latex also inhibited inflammation induced by subcutaneous carrageenan injection, cell migration, exudate volume, protein extravasations, increased levels of inflammatory mediators (nitric oxide, prostaglandin E2, TNF-α, and IL-6) produced in the pouch, and increased expression of the enzymes nitric oxide synthase and cyclooxygenase 2.

CONCLUSIONS

Our results indicate that the latex obtained from Hancornia speciosa demonstrates significant anti-inflammatory activity through the inhibition of nitric oxide, PGE2, and cytokine production, thus confirming the popular use of this plant as an anti-inflammatory agent.

Mechanisms of non-opioid analgesics beyond cyclooxygenase enzyme inhibition

Non-opioid analgesics including both selective and non-selective cyclooxygenase (COX) inhibitors and acetaminophen are the most widely used treatments for pain. Inhibition of COX is thought to be largely responsible for both the therapeutic and adverse effects of this class of drugs. Accumulating evidence over the past two decades has demonstrated effects of non-opioids beyond the inhibition of COX and prostaglandin synthesis that might also explain their therapeutic and adverse effects. These include their interaction with endocannabinoids, nitric oxide, monoaminergic, and cholinergic systems. Moreover, the recent development of microarray technology that allows the study of human gene expression suggests multiple pathways that may be related to the analgesic and anti-inflammatory effects of non-opioids. The present review will discuss the multiple actions of non-opioids and their interactions with these systems during inflammation and pain, suggesting that COX inhibition is an incomplete explanation for the actions of non-opioids and proposes the involvement of multiple selective targets for their analgesic, as well as, their adverse effects.

Eugenol suppressed the expression of lipopolysaccharide-induced proinflammatory mediators in human macrophages

Eugenol is commonly used as an analgesic agent during acute pulpitis and is a major component of root canal sealers. Despite the frequent applications of eugenol in the practice of dentistry, little is known about the role of eugenol under the status of inflammation. This study was aimed to investigate the influence of eugenol on human macrophages (U937) under the stimulation of lipopolysaccharide (LPS). Eugenol was shown to block the release of the bone resorbing mediators, including interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and prostaglandin E2 from LPS-stimulated macrophages. In contrast, eugenol alone did not alter the expression levels of these proinflammatory mediators in macrophages. Consistent with downregulation of bone-resorbing mediators, eugenol suppressed the messenger RNA expression of LPS-induced IL-1beta, TNF-alpha, and cyclooxygenase-2 in macrophages. The results suggest a potential anti-inflammatory effect of eugenol in the acute inflamed pulps and apical periodontitis.

Irreversible but not reversible pulpitis is associated with up-regulation of tumour necrosis factor-alpha gene expression in human pulp

AIM

To analyse the gene expression of tumour necrosis factor-alpha (TNF-alpha) in human dental pulps, under normal and inflammatory conditions and to examine the association between any observed alterations in the expression of this cytokine with the severity of the clinical symptoms.

METHODOLOGY

Eighteen pulpal samples were obtained from single-rooted human teeth. Six of the teeth were normal (group A), six had been diagnosed with reversible pulpitis (group B), and the remaining six were from teeth diagnosed with irreversible pulpitis (group C). TNF-alpha gene expression was semi-quantitatively analysed in each sample with RT-PCR, and the results from each group of teeth were compared with the Kruskal-Wallis and Mann-Whitney tests.

RESULTS

Tumour necrosis factor-alpha was detected in all three groups of dental pulp. Statistical analysis provided evidence of a significant increase of TNF-alpha gene expression associated with irreversible inflammation compared with healthy controls (P = 0.002). No such difference was detected in reversibly inflamed pulp in comparison to healthy teeth (P = 0.699).

CONCLUSION

Tumour necrosis factor-alpha gene expression in inflamed human dental pulp tissue is positively associated with the severity of clinical symptoms.

Cytokine-induced prostaglandin E2production and cyclooxygenase-2 expression in dental pulp cells: downstream calcium signalling via activation of prostaglandin EP receptor

AIM

To determine whether (i) proinflammatory cytokines stimulate prostaglandin E(2) (PGE(2)) production and cyclooxygenase (COX) gene expression in dental pulp cells, and (ii) pulp cells that express different prostaglandin E(2) receptor (EP) isoforms and their activation by PGE(2) leads to downstream Ca(2+) signalling.

METHODOLOGY

Cultured human dental pulp cells were exposed to interleukin (IL)-1beta and tumour necrotic factor-alpha (TNF-alpha). The expression of COX-1 and COX-2 was measured with reverse transcriptase-polymerase chain reaction (RT-PCR). The production of PGE(2) was measured using an enzyme-linked immunosorbent assay. Expression of prostaglandin EP receptor isoforms was studied by RT-PCR, whereas fura-2 fluorescence was used to measure calcium mobilization. The Kruskal-Wallis test and Wilcoxon sum rank test with Bonferroni correction were used for statistical analysis.

RESULTS

Interleukin-1beta and TNF-alpha stimulate PGE(2) production of human dental pulp cells (P < 0.05). IL-1beta stimulated the COX-2 but not COX-1 mRNA expression. Pulp cells express mainly EP2, EP3 and EP1 receptors as analysed by RT-PCR. PGE(2) (0.25-2 micromol L(-1)) stimulated the Ca(2+) mobilization as indicated by increase in fura-2 fluorescence.

CONCLUSIONS

Interleukin-1beta and TNF-alpha may stimulate PGE(2) production in dental pulp cells. Activation of prostaglandin EP receptors in dental pulp cells by PGE(2) may induce Ca(2+) signalling to regulate cellular biological activity during inflammation.

A Real Time Quantitative PCR Analysis and Correlation of COX-1 and COX-2 Enzymes in Inflamed Dental Pulps Following Administration of Three Different NSAIDs

Dental pain is encountered daily by clinicians. Nonsteroidal anti-inflammatory drugs (NSAIDs) commonly used for pain management are traditionally cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) inhibitors, and more recently selective COX-2 inhibitors. This study was designed to identify and quantify COX-1 and COX-2 gene expression level in inflamed rat molar pulps after administration of three NSAIDs: Celebrex, Vioxx, and Advil. Fifty male Wistar rats had their first and second molar pulps exposed and sealed with Cavit for 4 days. Rats were randomly divided into the three drug groups and two control groups. RNA was isolated from the rat pulps. Real Time Quantitative Reverse Transcriptase-Polymerase Chain Reaction assay, a relatively new PCR technique, was used to quantify COX-1 and COX-2 mRNA. Statistical analysis demonstrated no significant differences in COX-1 and COX-2 levels among the drug groups. However, Vioxx and Advil significantly reduced COX-2 expression levels compared to inflamed (positive control) pulps (p < 0.05).

Expression and Characterization of Vanilloid Receptor Subtype 1 in Human Dental Pulp Cell Cultures

The expression of the vanilloid receptor subtype 1 (VR1, TRPV1) was detected in human dental pulp fibroblasts (PF-10) using RT-PCR, Western blotting, and immunocytochemical analysis. As revealed by ELISA, capsaicin induced IL-6 expression in PF-10 cells, and the VR1 antagonist capsazepine dose-dependently inhibited capsaicin-induced IL-6 production, indicating that capsaicin-induced IL-6 expression is related to VR1 activation. The interaction between capsaicin and mitogen-activated protein kinases (MAPKs) was investigated. The phosphorylation of p38 MAPK and c-Jun NH2-terminal kinase (JNK) were detected after capsaicin stimulation. p38 MAPK is involved in capsaicin-induced IL-6 production, as shown by the use of specific inhibitors of this kinase. The result of EMSA showed that capsaicin inhibited tumor necrosis factor-alpha (TNF-alpha)-induced nuclear factor-kappa B (NF-kappaB) activation in PF-10 cell cultures. These results suggest that the activation of VR1 plays an important role in dental pulp inflammation.

Induction of vascular endothelial growth factor gene expression by proinflammatory cytokines in human pulp and gingival fibroblasts

Vascular endothelial growth factor (VEGF) enhances the permeability of blood vessels, which is an important vascular change observed during inflammatory processes. The purpose of this in vitro study was to investigate the effect of proinflammatory cytokines on the expression of VEGF mRNA gene in human pulp and gingival fibroblasts. Interlukin-1alpha (IL-1alpha) and tumor necrosis factor-alpha (TNF-alpha) were used to evaluate VEGF mRNA gene expression in human pulp and gingival fibroblasts. The levels of mRNAs were measured by quantitative reverse-transcriptase polymerase chain reaction analysis. Both IL-1alpha and TNF-alpha induced significantly high levels of VEGF mRNA gene expression in human pulp and gingival fibroblasts (p < 0.05). In addition, TNF-alpha was found to be more effective in the induction of VEGF mRNA gene expression in pulp than gingival fibroblasts (p < 0.05). Moreover, IL-1alpha was found to be more effective in the induction of VEGF mRNA gene expression than TNF-alpha in gingival fibroblast cultures (p < 0.05). These results indicate that proinflammatory cytokines can induce VEGF mRNA gene expression, and such an effect may partially contribute to the destruction of pulpal and periapical tissues through promoting expansion of the vascular network coincident to progression of the inflammation.

Induction of interleukin-6 gene expression by pro-inflammatory cytokines and black-pigmented Bacteroides in human pulp cell cultures

AIM

To investigate the effect of pro-inflammatory cytokines and black-pigmented Bacteroides on the expression of IL-6 gene in human pulp fibroblasts.

METHODOLOGY

IL-1alpha, tumour necrosis factor-alpha (TNF-alpha) and the supernatants of Porphyromonas endodontalis, P. gingivalis and Prevotella intermedia were used to evaluate IL-6 gene expression in human pulp fibroblasts. The levels of mRNAs were measured by the quantitative reverse-transcriptase polymerase chain reaction analysis.

RESULTS

Investigations of the time dependence of IL-6 mRNA expression in pro-inflammatory cytokines-treated cells revealed a rapid accumulation of the transcript after 2 h of exposure and remained elevated throughout the 24-h incubation period. In addition, black-pigmented Bacteroides also induced IL-6 gene expression in human pulp fibroblasts.

CONCLUSIONS

Pro-inflammatory cytokines and black-pigmented Bacteroides may be involved in developing pulpal inflammation through the stimulation of IL-6 production.