Matrix metalloproteinase-8 (MMP-8) in pulpal and periapical inflammation and periapical root-canal exudates

Cytokine expression of IL-8 before and after root canal treatment in patients with symptomatic apical periodontitis: A clinical trial

This study's objective was to compare the cytokine expression of IL-8 in periapical tissues of single-rooted teeth with symptomatic apical periodontitis (SAP) before and after root canal treatments. As well as, comparing IL-8 levels in peri-apical tissues between vital and necrotic teeth with SAP.

METHODOLOGY

Thirty-six patients were allocated according to their pulp status into two experimental groups (n = 18) receiving the same treatment protocol; group 1: Vital pulps with SAP, and group 2: non-vital pulps with SAP. Conventional endodontic treatment was done on two visits; isolation and disinfection of the operative field were undertaken, and two-stage access cavity preparation was implemented. The first pre-instrumentation peri-apical sample (S1) was collected prior to cleaning and shaping procedures. A 2.5% NaOCl irrigation was used to thoroughly irrigate the canal after performing root canal preparation utilising the ProTaper Next (PTN) rotary system. After 1 week, the second post-instrumentation peri-apical sample (S2) was collected. Using an ELISA kit, the quantity of IL-8 was evaluated following the collection of all samples.

RESULTS

In all pre-instrumentation samples, IL-8 was detected (100%). The level of IL-8 expression was significantly decreased from the S1 to S2 of all samples (p < 0.001). The intra-group comparison showed a statistically significant reduction in the level of IL-8 expression between S1 and S2 in both vital and non-vital groups where p < 0.001* in both groups. The inter-group comparison of levels of IL-8 expression (vital and non-vital) revealed a significant difference between both groups regarding the pretreatment sample with the higher levels of IL-8 shown in the non-vital group (p < 0.001). While in the post-treatment sample, both groups showed a significant reduction in the level of IL-8 expression but the difference between them was not statistically significant (p = 0.226).

CONCLUSION

Root canal instrumentation seems to be efficient in decreasing the levels of anti-inflammatory cytokines, namely IL-8. Further research should clarify how intra-canal medicaments affect inflammatory mediator levels.

Oral active matrix metalloproteinase-8 immunotest may be less accurate in haemato-oncologic patients

OBJECTIVES

This study examines the associations of active matrix metalloproteinase-8 (aMMP-8) point-of-care immunotest (Periosafe) outcomes with oral health of patients with haemato-oncologic diseases.

METHODS

Adult patients diagnosed with haematological diseases aimed to be treated with haematopoietic stem cell transplantation (HSCT) between 2018 and 2019 were included in the study. Clinical and radiological dental examination were taken immediately prior to transplantation. The presence of oral foci of infections, caries or periodontitis was examined and compared with the outcomes of aMMP-8 immunotest.

RESULTS

Acute oral infection foci were present in 11.9%, chronic in 44.1% and periodontitis in 42.0% of the 143 subjects. aMMP-8 immunotest was positive in 13.3% of all the 143 subjects. Among subjects with periodontitis (n = 60), the aMMP-8 immunotest was also positive in 13.3% of these subjects. However, the subjects with positive aMMP-8 immunotest (n = 19) had more often acute or chronic infection foci and more than one of the examined dental treatment needs compared with subjects with negative immunotest (all p < 0.05). There were no differences in age, sex, hyposalivation, DMFT-index values nor with plasma levels of leukocytes, neutrophils or C-reactive protein between subjects with positive or negative aMMP-8 immunotest.

CONCLUSIONS

aMMP-8 immunotest accuracy might be reduced, in relation to periodontitis, in haemato-oncologic patients.

The Reparative Function of MMP13 in Tertiary Reactionary Dentinogenesis after Tooth Injury

MMP13 gene expression increases up to 2000-fold in mineralizing dental pulp cells (DPCs), with research previously demonstrating that global MMP13 deletion resulted in critical alterations in the dentine phenotype, affecting dentine-tubule regularity, the odontoblast palisade, and significantly reducing the dentine volume. Global MMP13-KO and wild-type mice of a range of ages had their molar teeth injured to stimulate reactionary tertiary dentinogenesis. The response was measured qualitatively and quantitatively using histology, immunohistochemistry, micro-CT, and qRT-PCR in order to assess changes in the nature and volume of dentine deposited as well as mechanistic links. MMP13 loss affected the reactionary tertiary dentine quality and volume after cuspal injury and reduced Nestin expression in a non-exposure injury model, as well as mechanistic links between MMP13 and the Wnt-responsive gene Axin2. Acute pulpal injury and pulp exposure to oral fluids in mice teeth showed upregulation of the MMP13 in vivo, with an increase in the gene expression of Mmp8, Mmp9, and Mmp13 evident. These results indicate that MMP13 is involved in tertiary reactionary dentine formation after tooth injury in vivo, potentially acting as a key molecule in the dental pulp during dentine-pulp repair processes.

Presence of host and bacterial-derived collagenolytic proteases in carious dentin: a systematic review of ex vivo studies

Introduction and aim

The presence of host collagenases in the degradation of the protein matrix at later stages of carious dentin lesions development, as well as the potential involvement of bacterial collagenases, have been suggested but lack conclusive evidence. This study aims to conduct a systematic review to comprehensively assess the profile of host and bacterial-derived collagenolytic proteases in both root and coronal dentin carious lesions.

Methods

The search was performed in eight databases and the grey literature. Studies evaluating ex vivo dentin, extracted teeth, or biofilms from natural caries lesions were included. The methodological quality of studies was assessed using the Joanna Briggs Institute tool. Synthesis of the results and the certainty of evidence were performed following the Synthesis without Meta-analysis (SWiM) checklist and GRADE approach for narrative synthesis, respectively.

Results

From 935 recovered articles, 18 were included. Although the evidence was very uncertain, it was possible to suggest that 1) MMP-2, MMP-9, MMP-13, and CT-B may be increased in carious dentin when compared to sound dentin; 2) there is no difference in MMP-2 presence, while MMP-13 may be increased in root when compared to coronal carious dentin; 3) there is no difference of MMP-2 and MMP-9 expression/activity before and after cavity sealing; 4) MMP-8 may be increased in the dentin before cavity sealing compared to dentin after cavity sealing; 5) there is no difference of MMP-20 in irradiated vs. non-irradiated carious dentin. MMP-20 probably reduces in carious outer dentin when compared to carious inner dentin (moderate certainty). Genes encoding bacterial collagenolytic proteases and protein-degrading bacteria were detected in coronal and root carious lesions.

Conclusion

Trends in the direction of the effect were observed for some collagenolytic proteases in carious dentin, which may represent a potential target for the development of new treatments. (Protocol register-PROSPERO: CRD42020213141).

Periradicular tissue fluid-derived biomarkers for apical periodontitis: An in vitro methodological and in vivo cross-sectional study

BACKGROUND

Periradicular tissue fluid (PTF) offers a source of diagnostic, prognostic and predictive biomarkers for endodontic disease.

AIMS

(1) To optimize basic parameters for PTF paper point sampling in vitro for subsequent in vivo application. (2) To compare proteomes of PTF from teeth with normal apical tissues (NAT) and asymptomatic apical periodontitis (AAP) using high-throughput panels.

METHODOLOGY

(1) To assess volume absorbance, paper points (n = 20) of multiple brands, sizes and sampling durations were inserted into PBS/1%BSA at several depths. Wetted lengths (mm) were measured against standard curves to determine volume absorbance (μL). To assess analyte recovery, paper points (n = 6) loaded with 2 μL recombinant IL-1β (15.6 ng/mL) were eluted into 250 μL: (i) PBS; (ii) PBS/1% BSA; (iii) PBS/0.1% Tween20; (iv) PBS/0.25 M NaCl. These then underwent: (i) vortexing; (ii) vortexing/centrifugation; (iii) centrifugation; (iv) incubation/vortexing/centrifugation. Sandwich-ELISAs determined analyte recovery (%) against positive controls. (2) Using optimized protocols, PTF was retrieved from permanent teeth with NAT or AAP after accessing root canals. Samples, normalized to total fluid volume (TFV), were analysed to determine proteomic profiles (pg/TFV) of NAT and AAP via O-link Target-48 panel. Correlations between AAP and diagnostic accuracy were explored using principal-component analysis (PCA) and area under receive-operating-characteristic curves (AUC [95% CI]), respectively. Statistical comparisons were made using Mann-Whitney U, anova and post hoc Bonferonni tests (α < .01).

RESULTS

(1) UnoDent's 'Classic' points facilitated maximum volume absorbance (p < .05), with no significant differences after 60 s (1.6 μL [1.30-1.73]), 1 mm depth and up to 40/0.02 (2.2 μL [1.98-2.20]). For elution, vortexing (89.3%) and PBS/1% BSA (86.9%) yielded the largest IL-1β recovery (p < .05). (2) 41 (NAT: 13; AAP: 31) PTF samples proceeded to analysis. The panel detected 18 analytes (CCL-2, -3, -4; CSF-1; CXCL-8, -9; HGF; IL-1β, -6, -17A, -18; MMP-1, -12; OLR-1; OSM; TNFSF-10, -12; VEGF-A) in ≥75% of AAP samples at statistically higher concentrations (p < .01). CXCL-8, IL-1β, OLR-1, OSM and TNFSF-12 were strongly correlated to AAP. 'Excellent' diagnostic performance was observed for TNFSF-12 (AUC: 0.94 [95% CI: 0.86-1.00]) and the PCA-derived cluster (AUC: 0.96 [95% CI: 0.89-1.00]).

CONCLUSIONS

Optimized PTF sampling parameters were identified in this study. When applied clinically, high-throughput proteomic analyses revealed complex interconnected networks of potential biomarkers. TNFSF-12 discriminated periradicular disease from health the greatest; however, clustering analytes further improved diagnostic accuracy. Additional independent investigations are required to validate these findings.

The homeostasis and therapeutic applications of innate and adaptive immune cells in periodontitis

OBJECTIVES

Periodontitis (PD) is one of the most common dental disorders. This chronic oral inflammation is caused by complicated interrelations between bacterial infections, dysregulated immune reactions, and environmental risk factors. A dysregulated immune response can lead to inflammatory bone resorption by allowing the recruitment of pro-inflammatory immune cells to the periodontal tissues.

SUBJECTS

The recruitment of innate and adaptive immune cells in PD initiates the acute and following chronic inflammatory processes. The inflamed tissues, on the other hand, can be restored if the anti-inflammatory lineages are predominantly established in the periodontal tissues. Therefore, we aimed to review the published literature to provide an overview of the existing knowledge about the role of immune cells in PD, as well as their possible therapeutic applications.

RESULTS

Experimental studies showed that drugs/systems that negatively regulate inflammatory cells in the body, as well as interventions aimed at increasing the number of anti-inflammatory cells such as Tregs and Bregs, can both help in the healing process of PD.

CONCLUSION

Targeting immune cells or their positive/negative manipulations has been demonstrated to be an effective therapeutic method. However, to use this sort of immunotherapy in humans, further pre-clinical investigations, as well as randomized clinical trials, are required.

Puerarin inhibits inflammation and lipid accumulation in alcoholic liver disease through regulating MMP8

Alcoholic liver disease (ALD) is a growing global health concern, and its early pathogenesis includes steatosis and steatohepatitis. Inhibiting lipid accumulation and inflammation is a crucial step in relieving ALD. Evidence shows that puerarin (Pue), an isoflavone isolated from Pueraria lobata, exerts cardio-protective, neuroprotective, anti-inflammatory, antioxidant activities. However, the therapeutic potential of Pue on ALD remains unknown. In the study, both the NIAAA model and ethanol (EtOH)-induced AML-12 cell were used to explore the protective effect of Pue on alcoholic liver injury in vivo and in vitro and related mechanism. The results showed that Pue (100 mg·kg-1) attenuated EtOH-induced liver injury and inhibited the levels of SREBP-1c, TNF-α, IL-6 and IL-1β, compared with silymarin (Sil, 100 mg·kg-1). In vitro results were consistent within vivo results. Mechanistically, Pue might suppress liver lipid accumulation and inflammation by regulating MMP8. In conclusion, Pue might be a promising clinical candidate for ALD treatment.

Effect of different retreatment files using different kinematics on the release of inflammatory mediators in root canal retreatment of single-rooted teeth: a randomized clinical trial

OBJECTIVES

This randomized clinical trial aimed to evaluate the effect of two rotaries (ProTaper Universal Retreatment (PTUR)), D-Race (DR) + XP-Endo Finisher R (XPFR) and one reciprocating (Reciproc Blue (RB) retreatment techniques on the release of neuropeptides (Substance P, calcitonin gene-related peptide (CGRP)), and cytokines (IL-6 and IL-10) in periapical fluid in root canal retreatment of single-rooted teeth.

MATERIALS AND METHODS

In this randomized clinical trial (ClinicalTrials.gov ID: NCT05039502), seventy-five patients scheduled for retreatment were randomly divided into 3 groups according to the file system used to remove root canal filling materials (n = 25): PTUR, RB, and DR + XPFR. After reshaping and disinfection of the root canals, periapical fluid samples were taken, and the levels of Substance P, CGRP, IL-6, and IL-10 were measured by enzyme-linked immunosorbent assay (ELISA) test. Data were analyzed using the Kruskal-Wallis and chi-square tests. The level of significance was set as p = 0. 05.

RESULTS

All the allocated participants received the intervention and were analyzed. There was no statistically significant difference among groups in terms of gender, age, tooth localization, and the distribution of analgesic use after treatment (p values 0.799, 0.095, 0.637, 1.000, respectively). No statistically significant difference was found in terms of the levels of Substance P, CGRP, and IL-10 among groups (p > .05), except IL-6.

CONCLUSIONS

PTUR, RB, and DR + XPFR files have comparable results in the expression of inflammatory mediators.

CLINICAL RELEVANCE

Retreatment files powered with rotary or reciprocating motion produced similar neuropeptide and cytokine levels in patients.

Matrix Metalloproteinases in Dental and Periodontal Tissues and Their Current Inhibitors: Developmental, Degradational and Pathological Aspects

Objectives: This review article aims to describe some of the roles of Matrix metalloproteinases (MMPs) in enamel, dentine, dental caries, hybrid layer degradation, pulp and periodontal tissues, throwing light on their current inhibitors. The article addresses the potential of MMPs to serve as biomarkers with diagnostic and therapeutic value. Design: The sections of this review discuss MMPs’ involvement in developmental, remodeling, degradational and turnover aspects of dental and periodontal tissues as well as their signals in the pathogenesis, progress of different lesions and wound healing of these tissues. The literature was searched for original research articles, review articles and theses. The literature search was conducted in PubMed and MEDLINE for articles published in the last 20 years. Results: 119 published papers, two textbooks and two doctoral theses were selected for preparing the current review. Conclusions: MMPs are significant proteases, of evident contribution in dental and periapical tissue development, health and disease processes, with promising potential for use as diagnostic and prognostic disease biomarkers. Continuing understanding of their role in pathogenesis and progress of different dental, periapical and periodontal lesions, as well as in dentine-pulp wound healing could be a keystone to future diagnostic and therapeutic regimens.

Association between Endodontic Infection, Its Treatment and Systemic Health: A Narrative Review

The ‘Focal Infection Era in Dentistry’ in the late 19th and early 20th century resulted in widespread implementation of tooth extraction and limited the progress of endodontics. The theory proposed that bacteria and toxins entrapped in dentinal tubules could disseminate systemically to remote body parts, resulting in many types of degenerative systemic diseases. This theory was eventually refuted due to anecdotal evidence. However, lately there has been increased interest in investigating whether endodontic disease could have an impact on general health. There are reviews that have previously been carried out on this subject, but as new data have emerged since then, this review aims to appraise the available literature investigating the dynamic associations between apical periodontitis, endodontic treatment, and systemic health. The available evidence regarding focal infection theory, bacteraemia and inflammatory markers was appraised. The review also collated the available research arguing the associations of apical periodontitis with cardiovascular diseases, diabetes mellitus, adverse pregnancy outcome and autoimmune disorders, along with the effect of statins and immunomodulators on apical periodontitis prevalence and endodontic treatment prognosis. There is emerging evidence that bacteraemia and low-grade systemic inflammation associated with apical periodontitis may negatively impact systemic health, e.g., development of cardiovascular diseases, adverse pregnancy outcomes, and diabetic metabolic dyscontrol. However, there is limited information supporting the effect of diabetes mellitus or autoimmune disorders on the prevalence and prognosis post endodontic treatment. Furthermore, convincing evidence supports that successful root canal treatment has a beneficial impact on systemic health by reducing the inflammatory burden, thereby dismissing the misconceptions of focal infection theory. Although compelling evidence regarding the association between apical periodontitis and systemic health is present, further high-quality research is required to support and establish the benefits of endodontic treatment on systemic health.

A Mini Review: The Potential Biomarkers for Non-invasive Diagnosis of Pulpal Inflammation

For assessing the adequacy of vital pulp therapy for an inflamed pulp, the use of non-invasive diagnostic tools is necessary to avoid further damage to the teeth. Detection of biomarkers that are indicative of the inflammatory status in pulp can be a promising tool for this purpose. These biomarkers need to be reliably correlated with pulpal inflammation and to be easily detected without pulp exposure. This mini-review article aims to review biomarkers that are present in gingival crevicular fluid (GCF) in inflamed pulp conditions. Several studies have reported the availability of various biomarkers including cytokines, proteases, elastase, neuropeptides, and growth factors. Non-invasive pulpal diagnostic methods will be useful as well to determine reversibility, irreversibility, or necrosis of inflamed pulp. These types of molecular diagnoses via analyzing the proteome have revolutionized the medical field, and are one of the most promising empirical methodologies that a clinician can utilize for the proactive identification of pulpal disease.

MMP-9 Levels and NaOCl Lavage in Randomized Trial on Direct Pulp Capping

Outcome expectations of direct pulp capping in carious teeth are obscured by a clinically unknown infiltration and breakdown of the dental pulp tissue. Histologic studies showed that this soft tissue breakdown is related to the innate immune system. We hypothesized 1) that a neutrophil biomarker could predict the outcome of direct pulp capping and 2) that using sodium hypochlorite (NaOCl) as a lavage solution to remove necrotized infected pulp tissue could improve it. In this randomized trial in mature posterior teeth causing no or mild discomfort with carious pulpal exposures, pulpal fluid was collected to assess neutrophil gelatinase (matrix metalloproteinase 9 [MMP-9]) per total protein (TP) levels as a predictive local biomarker. Subsequently, the dentin-pulp wound was randomly washed with a 2.5% NaOCl or a physiologic saline solution (1:1 allocation), capped with mineral trioxide aggregate, and the tooth was immediately restored with a resin-based composite restoration. Ninety-six patients were included, and 84 individuals could be followed up to treatment failure or clinically confirmed pulp survival after a minimum of 1 y. The entire data were fitted to a Cox proportional hazards model to assess the influence of the observational variables MMP-9/TP and discomfort with the randomized lavage treatment on pulp survival. The Kaplan-Meier pulp survival rates after 1 y were 55% for saline and 89% for NaOCl lavage. The inflammatory state of the pulp tissue as reflected by MMP-9/TP levels and NaOCl lavage had a highly significant (P < 0.001 and P = 0.004, respectively) impact on pulp survival, while mild preoperative discomfort did not. In conclusion, MMP-9/TP showed great promise as a predictive local biomarker, and NaOCl lavage considerably improved the survival time of cariously exposed and directly capped pulps.

A critical analysis of research methods to study clinical molecular biomarkers in Endodontic research

The authors of this narrative review aimed to address various experimental methods and make recommendations for how research should move forward in the context of studying biomarkers in clinical Endodontic research. The approach adopted is exemplified using two prominent clinical problems, namely (a) the ‘reversible’ versus ‘irreversible’ pulpitis conundrum and (b) persistent idiopathic dentoalveolar pain (PIDAP). Pulpitis under deep caries or dentinal cracks is understood from a histological perspective, but clinical assessment tools to indicate irreversibly inflamed aspects of the dental pulp are elusive. PIDAP, on the other hand, is a diagnosis of exclusion; its pathophysiology is complex and not understood sufficiently to avoid unnecessary dental treatments. This review addresses how diagnostic biomarkers could further our understanding of those and other clinical problems, and how issues can be tackled from a methodological point of view. Hence, different methodological approaches to identify suitable diagnostic biomarker(s) or use known biomarkers are presented. The importance of asking a relevant research question, collecting the most suitable fluid and using the ideal collection vehicle for the research question under investigation is discussed based on the defined clinical problems.

EZH2 Promotes Extracellular Matrix Degradation via Nuclear Factor-κB (NF-κB) and p38 Signaling Pathways in Pulpitis

Pulpitis is a complicated chronic inflammatory process which can be in a dynamic balance between damage and repair. The extracellular matrix plays an important regulatory role in wound healing and tissue repair. The aim of this study was to explore the role of the epigenetic mark, enhancer of zeste homolog 2 (EZH2) on the degradation of extracellular matrix during pulpitis. Quantitative polymerase chain reaction was used to assess the expression of matrix metalloproteinases (MMPs) and type I collagen in human dental pulp cells (HDPCs) upon EZH2 and EI1 (EZH2 inhibitor) stimulation. The mechanism of EZH2 affecting extracellular matrix was explored through quantitative polymerase chain reaction and Western blot. A rat model of dental pulp inflammation was established, and the expression of type I collagen in dental pulp under EZH2 stimulation was detected by immunohistochemical staining. EZH2 upregulated the expression of MMP-1, MMP-3, MMP-8, and MMP-10 and decreased the production of type I collagen in HDPCs, while EI1 had the opposite effect. EZH2 activated the nuclear factor-kappa B (NF-κB) and p38 signaling pathways in HDPCs, the inhibition of which reversed the induction of MMPs and the suppression of type I collagen. EZH2 can downregulate the type I collagen levels in an experimental model of dental pulpitis in rats. EZH2 promotes extracellular matrix degradation via nuclear factor-κB (NF-κB) and P38 signaling pathways in pulpitis. EZH2 can decrease the type I collagen levels in vivo and in vitro.

Influence of TEGDMA monomer on MMP-2, MMP-8, and MMP-9 production and collagenase activity in pulp cells

OBJECTIVES

Resin-based composites may leach monomers such as triethylene-glycol dimethacrylate (TEGDMA), which could contribute to intrapulpal inflammation. The aim of this investigation was to examine whether various concentrations of TEGDMA are able to influence dentally relevant Matrix metalloproteinase (MMP)-2, MMP-8, and MMP-9 production, total collagenase/gelatinase activity in pulp cells, and suggest possible signaling mechanisms.

MATERIALS AND METHODS

Pulp cells were cultured, followed by a 1-day exposure to sublethal TEGDMA concentrations (0.1, 0.2, and 0.75 mM). Total MMP activity was measured by an EnzCheck total collagenase/gelatinase assay, while the production of specific MMPs and the relative changes of phosphorylated, i.e., activated signaling protein levels of extracellular signal-regulated kinase (ERK)1/2, p38, c-Jun N-terminal kinase (JNK) were identified by western blot. Immunocytochemistry image data was also plotted and analyzed to see whether TEGDMA could possibly alter MMP production.

RESULTS

An increase in activated MMP-2, MMP-8, and MMP-9 production as well as total collagenase activity was seen after a 24-h exposure to the abovementioned TEGDMA concentrations. Increase was most substantial at 0.1 (P = 0.002) and 0.2 mM (P = 0.0381). Concurrent p-ERK, p-p38, and p-JNK elevations were also detected.

CONCLUSIONS

Results suggest that monomers such as TEGDMA, leached from resin-based restorative materials, activate and induce the production of dentally relevant MMPs in pulp cells. Activation of ERK1/2, p38, or JNK and MMP increase may play a role in and/or can be part of a broader stress response. Clinical relevance Induction of MMP production and activity may further be components in the mechanisms of intrapulpal monomer toxicity.

Anti-Inflammatory Effects of Melatonin and 5-Methoxytryptophol on Lipopolysaccharide-Induced Acute Pulpitis in Rats

Aim

The aim of this study was to investigate the possible therapeutic impacts of two pineal hormones, melatonin and 5-methoxytryptophol (5-MTX), in a rat model of acute pulpitis by analyzing biochemical and histopathological parameters.

Methods

This research was done using 32 male and female Wistar albino rats with weight between 200 and 250 g. The rats were randomly divided into four groups: a control group (rats without any treatment), acute pulpitis (AP) group, AP+melatonin group, and AP+5-MTX group. In the AP-induced groups, the crowns of the upper left incisors were removed horizontally. Lipopolysaccharide solution was applied to the exposed pulp tissue before the canal orifices were sealed with a temporary filling material. Melatonin (10 mg/kg) and 5-MTX (5 mg/kg) were administered intraperitoneally. The rats were sacrificed 24 hours after pulp injury, and trunk blood and pulp samples were collected. The concentrations of TNF-α, IL-1β, MMP-1, and MMP-2 in sera and pulp samples were determined using ELISA assay kits.

Results

TNF-α, IL-1β, MMP-1, and MMP-2 levels in the serum and pulp tissues were considerably higher in the AP group than the control group (p < 0.01‐0.001). In the AP+melatonin and AP+5-MTX groups, TNF-α, IL-1β, MMP-1, and MMP-2 levels in the serum and pulp tissues were significantly lower than in the AP group (p < 0.05‐0.001).

Conclusions

Both melatonin and 5-MTX provided protective effects on acute pulpitis, which indicates they may be promising as a therapeutic strategy for oral disease.

Extracellular matrix degradation by host matrix metalloproteinases in restorative dentistry and endodontics: An overview

Matrix metalloproteinases (MMPs) are a group of over 25 secreted and membrane-bound enzymes responsible for pericellular substrate degeneration. In response to injury, they play key roles in morphogenesis, wound healing, tissue repair and remodeling. They have been isolated from dentin, odontoblasts, pulp and periapical tissue. They play a major role in the formation of dentin matrix and secondary and tertiary dentin. These are also responsible for releasing dentinal growth factors. MMP family proteins elicit a dual role in the pathogenesis of inflammation, stimulating protective innate and/or adaptive immune functions, as well as tissue destruction. The main organic component of tooth structure is collagen, and MMPs that degrade collagen and the extracellular matrix have been implicated in the progression of dental caries, dental erosion as well as degradation of the hybrid layer. MMPs have also been shown to be active in pulpitis, and studies have shown that they can be used as diagnostic markers of pulpal and periapical inflammation. This review describes the role of MMPs in dental caries, dental erosion, bond stability as well as in pulpal and periapical inflammation.

Osteoclast formation, inflammation, and matrix metalloproteinase-9 are downregulated in bone repair following root canal treatment in dogs teeth

OBJECTIVES

The aim of this study was to investigate the inflammatory infiltrate, osteoclast formation, and expression of MMP-9 during the healing phase following root canal treatment in teeth with apical periodontitis.

MATERIALS AND METHODS

Apical periodontitis was induced in dogs teeth, and root canal treatment was performed in a single visit or using calcium hydroxide as intracanal medication. One hundred and eighty days following treatment the presence of inflammation was examined, and the tissues were stained to detect osteoclasts by means of a tartrate resistant alkaline phosphatase (TRAP) assay. Synthesis of MMP-9 was detected using Western blotting and immunohistochemistry.

RESULTS

Teeth with apical periodontitis that had root canal therapy performed in a single visit presented a higher synthesis of MMP-9 compared with root canal treatment using calcium hydroxide. Treatment with calcium hydroxide resulted in a reduced amount of inflammatory cells and MMP-9 positive cells. Osteoclast formation, the number of MMP-9 positive osteoclasts and cementocytes, was reduced following root canal treatment, regardless of the root canal treatment protocol used.

CONCLUSION

Root canal treatment reduced the amount of inflammatory cells and osteoclasts in periapical area. The use of calcium hydroxide as intracanal medication resulted in a lower synthesis of MMP-9, though the number of osteoclasts and MMP-9 positive osteoclasts were similar between the groups.

CLINICAL RELEVANCE

Periapical bone repair following root canal treatment is impacted by therapy performed either in single visit or using calcium hydroxide dressing measured by inflammatory cell recruitment, osteoclast formation, and MMP-9 synthesis.

Association between concentration of active MMP-9 in pulpal blood and pulpotomy outcome in permanent mature teeth with irreversible pulpitis - a preliminary study

AIM

To investigate the correlation between the concentration of active-matrix metalloproteinases-9 (aMMP-9) in pulpal blood and the outcome of pulpotomy in mature permanent teeth with symptomatic irreversible pulpitis (SIP).

METHODOLOGY

Forty permanent molar teeth with a clinical diagnosis of SIP and normal apical tissues with periapical index (PAI) score ≤ 2 and ten permanent teeth (8 molars and two premolars) with a diagnosis of normal pulp that required root canal treatment for prosthetic reasons from patients between the ages of 15-35 years were recruited. All clinical procedures were performed under local anaesthesia and rubber dam isolation. After access opening, the coronal pulp tissue was amputated up to the canal orifice. A 100 μL volume of the pulpal blood was collected using a micropipette and transported to the laboratory. Sodium hypochlorite (2.5 %) was used as a haemostatic agent, and mineral trioxide aggregate (MTA) was used as the pulp capping material. The tooth was restored with composite at the same visit. Teeth with normal pulps were treated with single-visit root canal treatment. Patients with pulpotomy were recalled at 6 and 12 months. Outcome assessment of teeth with pulpotomy was carried out at 12 months and was categorized as success (asymptomatic patients with PAI score ≤ 2) or failure (symptomatic patients or PAI score ≥ 3). Quantification of aMMP-9 in pulpal blood was achieved using a fluorometric assay. The following statistical analyses were performed to assess the data: t-test, Fisher's exact test, kappa coefficient, non-parametric test, Wilcoxon rank-sum test, Spearman rank correlation test and receiver operating characteristic curve (ROC).

RESULT

The success rate of pulpotomy was 88 % at 12-months. There was a significant difference between the median concentrations of aMMP-9 in pulpal blood of teeth with normal pulps (52 (12-96) ng mL^-1 :) and SIP (193.3 (25.8-607.7) ng mL^-1 :) (P = 0.0003) and successful (132.3 (25.8-548.3) ng mL^-1 :) and failed cases (512.4 (334.8-607.7 ng mL^-1 :) (P = 0.0015) of MTA pulpotomy. A significant association was established between aMMP-9 concentration and outcome of pulpotomy. The area under the receiver operating characteristics curve (0.9484, 95%CI) suggested excellent discriminatory power of aMMP-9 concentration in pulpal blood to predict the pulpotomy outcome.

CONCLUSION

The pulpal blood concentration of aMMP-9 was significantly associated with the outcome of pulpotomy in teeth with symptomatic irreversible pulpitis, where it may be used as a potential prognostic biomarker.

Comparison of Neurokinin A, Substance P, Interleukin 8, and Matrix Metalloproteinase-8 Changes in Pulp tissue and Gingival Crevicular Fluid Samples of Healthy and Symptomatic Irreversible Pulpitis Teeth

INTRODUTION

The aim of this study was to compare levels of neurokinin A (NKA), substance P (SP), interleukin (IL)-8, and matrix metalloproteinase-8 (MMP-8) in pulp tissue and gingival crevicular fluid (GCF) samples of healthy and symptomatic irreversible pulpitis teeth.

METHODS

Forty patients diagnosed with healthy and symptomatic irreversible pulpitis teeth were included in this study. NKA, SP, IL-8, and MMP-8 levels were measured using the enzyme-linked immunosorbent assay test after pulp and GCF samples were obtained from healthy (n = 20) and symptomatic irreversible pulpitis teeth (n = 20). GCF sampling of 40 teeth was repeated 1 week later. Routine root canal treatment procedures of the teeth were performed, and the treatment process was completed. As a control group, GCF samples were taken from the contralateral teeth in both groups. Statistical analysis was performed using dependent and independent t tests, analysis of variance, Kruskal-Wallis, Mann-Whitney U tests, and Pearson correlation analysis.

RESULTS

Comparing the groups, all mediator levels were significantly higher in the pulp samples in the pulpitis group compared with the healthy group (NKA: P < .001, SP: P = .005, IL-8: P < .001, and MMP-8: P < .001). Likewise, in the pulpitis group, all mediator levels were significantly higher in the first GCF samples compared with the healthy group (NKA: P = .01, SP: P < .001, IL-8: P = .001, and MMP-8: P < .001).

CONCLUSIONS

It was observed that NKA, SP, IL-8, and MMP-8 increased significantly in pulp tissue and GCF specimens of symptomatic irreversible pulpitis teeth compared with pulp tissue and GCF specimens of healthy teeth. Second, it was determined that NKA, SP, IL-8, and MMP-8 levels decreased significantly in GCF samples in teeth diagnosed with symptomatic irreversible pulpitis 1 week after the removal of inflamed pulp. Finally, SP, IL-8, and MMP-8 levels were found to be higher in pulp tissue samples of the patients with symptomatic irreversible pulpitis with higher pain scores than those with low pain scores.

Metalloproteinase 14 (MMP-14) and hsa-miR-410-3p expression in human inflamed dental pulp and odontoblasts

The objective of this study is to evaluate MMP-14 expression in odontoblasts and in the bulk of dental pulp of teeth with pulpitis; to determine the expression of microRNA-410 (miR-410) in pulp tissue, since sequence analysis suggests that miR-410 has potential binding site on MMP-14’s 3′UTR, and hence, can regulate expression of the latter one. Tissue samples of dental pulp from teeth with pulpitis and healthy (control) were formalin fixed and paraffin embedded (FFPE). Samples were examined using immunohistochemical staining for MMP-14 and the expression of miR-410 was evaluated using qRT-PCR. In both, healthy and inflamed pulp odontoblasts stained more intensively than remaining pulp tissue, but this difference was not statistically significant. More positive staining was observed in inflamed pulps compared to healthy pulps. Expression of miR-410 was found significantly lower in inflamed pulps than in healthy ones. In the two examined zones, odontoblasts and remaining pulp, miR-410 was expressed on a similar level. No statistically significant correlation of miR-410 and MMP-14 expression was found. We showed that inflammation changes the MMP-14 expression in pulp tissue and odontoblasts. This study demonstrates for the first time miR-410 expression in human dental pulp and that expression of this microRNA was downregulated in inflamed dental pulp and odontoblasts.

Downregulation of microRNA-204 increases the expression of matrix metallopeptidase 9 in pediatric patients with pulpitis and Helicobacter pylori infection in the stomach

The present study examined the expression of microRNA (miRNA or miR)-204 in pulp tissues, blood and saliva from pediatric patients with pulpitis and an underlying Helicobacter pylori (Hp) infection in the stomach, and the mechanism of the associated regulation by miR-204 was assessed. A total of 26 children with pulpitis who received tooth extraction at the Children's Hospital of Nanjing Medical University (Nanjing, China) between December 2014 and August 2016 were diagnosed with Hp infection in the stomach and included in the present study (HP⁺ group); furthermore, 19 children with pulpitis but without Hp infection in the stomach were enrolled as a control (HP^- group). Pulp tissues, blood (serum) and saliva samples were collected from all subjects. Reverse-transcription quantitative polymerase chain reaction was used to determine the expression of miR-204 and matrix metalloproteinase 9 (MMP9) mRNA. Western blot analysis was performed to determine MMP9 protein expression in pulp tissues, while ELISA was performed to measure the contents of MMP9 in serum and saliva. A dual luciferase reporter assay was used to identify the direct interaction between miR-204 and its target protein. The results indicated that Hp infection in the stomach was associated with an upregulation of MMP9 mRNA and protein in pulp tissues, serum and saliva from children with pulpitis. Furthermore, the levels of miR-204 in pulp tissues, serum and saliva from children with pulpitis and Hp infection in the stomach were significantly reduced. miR-204 was confirmed to regulate the expression of MMP9 by directly binding with the 3'-untranslated region of MMP9 mRNA. The present study demonstrated that MMP9 expression in pulp tissues, blood and saliva from children with pulpitis and Hp infection in the stomach was upregulated, while miR-204 expression was downregulated. miR-204 may affect inflammatory processes and other oral diseases in children with pulpitis and Hp infection via MMP9, and may be a potential marker for the detection of Hp infection in children with pulpitis.

Effects of alpha-lipoic acid therapy on experimentally induced apical periodontitis: a biochemical, histopathological and micro-CT analysis

AIM

To investigate the possible therapeutic effects of alpha-lipoic acid (ALA) in a model of chronic apical periodontitis in rats by analysing biochemical, histopathological and micro-CT parameters.

METHODOLOGY

The study was approved by the Animal Ethics Committee of the Near East University. Thirty-two Wistar rats were divided into four groups of eight rats each: Control Group; ALA Group; AP Group; AP + ALA Group. In the AP and AP + ALA groups, the pulp chambers of the mandibular first molars were surgically exposed and were left open to the oral environment for 4-weeks to allow the establishment of periapical lesions. The rats in the Control and AP groups were treated intraperitoneally with saline solution (with a daily dose of 100 mg kg^-1 , for 28 days after periapical lesion induction). The rats in the ALA and AP + ALA groups were treated intraperitoneally with ALA (with a daily dose of 100 mg kg^-1 , for 28 days after periapical lesion induction). After decapitation, the trunk blood was collected for the assessment of biochemical parameters. The mandibles were surgically removed and dissected for histopathologic analysis and further scanned with micro-CT. Groups of data were compared with a two-way analysis of variance (two-way anova) followed by Sidak's multiple comparison tests. Values of P < 0.05 were regarded as significant.

RESULTS

TNF-α, IL-1β, MMP-1, MMP-2 levels were significantly lower in AP + ALA group compared with AP group (P < 0.05). There was a significant difference between the AP and AP + ALA groups according to assessment of the inflammatory scores (P < 0.05). The periapical inflammatory infiltrates were significantly more severe (P < 0.05) in the AP group. The AP + ALA group exhibited lower values both in terms of surface area and volume of resorption cavities than the AP group and this difference was significant (P < 0.05).

CONCLUSION

alpha-lipoic acid treatment provided therapeutic effects on the inhibition of periapical bone loss.

Regulation of matrix metalloproteinase-3 gene expression in inflammation: A molecular study

Introduction

Matrix metalloproteinases (MMPs) play a significant role in the efficient tissue turnover and remodeling. This study focuses on the regulation of the MMPs by the protein kinases at the level of gene expression and their signaling pathways.

Materials and Methods

Lipopolysaccharide-induced murine macrophage-like RAW 264.7 cell lines were obtained and maintained in Dulbecco's modified Eagle's medium plus 10% fetal bovine serum under optimal temperatures. Primers used were MMP-3 forward primer, MMP-3 reverse primer, and glyceraldehyde-3-phosphate dehydrogenase forward primer and glyceraldehyde-3-phosphate reverse primer. Total RNA was isolated, the sample was prepared, and electrophoresis was performed. The first strand of cDNA was synthesized and amplification of specific isolated gene using polymerase chain reactor (PCR). The amplified products were then separated on a 1.0% agarose gel in 1XTBE at 75 V for 3 h. The gel was stained with ethidium bromide, and the amplified product was visualized and photographed on Gel Doc system.

Results

Real-time PCR showed only bands at expected size of 595 bp for internal control amplification of glyceraldehyde-3-dehydrogenase gene. Analysis was done with densitometry, and these values are compared with the negative control. Results showed a statistically significant rise in the relative levels of MMP-3-mRNA when compared with negative control at 1, 2, and 3 h.

Conclusion

This study proved the significantly increased levels of MMP gene at different period, thereby it can be concluded that MMP-3 levels are higher in inflammatory conditions.

MMP-9 in Dentinal Fluid Correlates with Caries Lesion Depth

The analysis of molecular cues in dentinal fluid from an excavated cavity could improve diagnostics in the context of minimally invasive caries treatment. In the current clinical trial we assessed whether the dentinal fluid levels of MMP-9 (matrix metalloproteinase-9; neutrophil gelatinase) would increase with the progression of carious lesions. MMP-9 is associated with neutrophil-related tissue breakdown in the pulp. Absolute MMP-9 levels were contrasted against the levels of MMP-2, an enzyme related to normal tissue turnover. Dentinal fluid was collected below deep and shallow caries from molars and premolars within the same patients aged 18 years and older (n = 30, 1 tooth per group/patient). Experimental teeth were isolated under a rubber dam prior to excavation. Dentinal fluid was collected from the bottom of the cavity using a size 25 paper point. MMP levels were assessed using an enzyme-linked immunosorbent assay. Nonparametric methods were applied to test for differences between groups. Significantly more (p < 0.05, Wilcoxon test) MMP-9 was collected from the deep carious lesions than from the shallow counterparts. Pairwise comparison of MMP-9 values within patients revealed that there was more MMP-9 collected from deep lesions than from shallow counterparts in 27 of the 30 individuals under investigation (pairwise Wilcoxon test, p < 0.001). In contrast, no such difference existed for MMP-2. There was a high correlation between MMP-9 from deep and shallow lesions (Spearman's ρ = 0.72, p < 0.001), indicating that patients with more MMP-9 in the deep carious lesion also tended to have more MMP-9 in the shallow lesion.

Decreased levels of matrix metalloproteinase-2 in root-canal exudates during root canal treatment

OBJECTIVE

To determine the matrix metalloproteinase-2 (MMP-2) levels in root-canal exudates from teeth undergoing root-canal treatment.

MATERIAL AND METHODS

The root-canal exudates from six teeth with normal pulp and periradicular tissues that required intentional root canal treatment for prosthodontic reasons and from twelve teeth with pulp necrosis and asymptomatic apical periodontitis (AAP) were sampled with paper points for bacterial culture and aspirated for the detection of proMMP-2 and active MMP-2 by gelatin zymography and the quantification of MMP-2 levels by ELISA.

RESULTS

By gelatin zymography, both proMMP-2 and active MMP-2 were detected in the first collection of root-canal exudates from teeth with pulp necrosis and AAP, but not from teeth with normal pulp, and their levels gradually decreased and disappeared at the last collection. Consistently, ELISA demonstrated a significant decrease in MMP-2 levels in the root-canal exudates of teeth with pulp necrosis and AAP following root canal procedures (p<0.05). Furthermore, the MMP-2 levels were significantly lower in the negative bacterial culture than those in the positive bacterial culture (p<0.001).

CONCLUSIONS

The levels of MMP-2 in root-canal exudates from teeth with pulp necrosis and AAP were gradually reduced during root canal procedures. Future studies are required to determine if MMP-2 levels may be used as a biomolecule for the healing of apical lesions, similar to the clinical application of MMP-8 as a biomarker.

Quaternary ammonium-based biomedical materials: State-of-the-art, toxicological aspects and antimicrobial resistance

Microbial infections affect humans worldwide. Many quaternary ammonium compounds have been synthesized that are not only antibacterial, but also possess antifungal, antiviral and anti-matrix metalloproteinase capabilities. Incorporation of quaternary ammonium moieties into polymers represents one of the most promising strategies for preparation of antimicrobial biomaterials. Various polymerization techniques have been employed to prepare antimicrobial surfaces with quaternary ammonium functionalities; in particular, syntheses involving controlled radical polymerization techniques enable precise control over macromolecular structure, order and functionality. Although recent publications report exciting advances in the biomedical field, some of these technological developments have also been accompanied by potential toxicological and antimicrobial resistance challenges. Recent evidenced-based data on the biomedical applications of antimicrobial quaternary ammonium-containing biomaterials that are based on randomized human clinical trials, the golden standard in contemporary medicinal science, are included in the present review. This should help increase visibility, stimulate debates and spur conversations within a wider scientific community on the implications and plausibility for future developments of quaternary ammonium-based antimicrobial biomaterials.

Painful Tooth Stimulation Elevates Matrix Metalloproteinase-8 Levels Locally in Human Gingival Crevicular Fluid

Recent studies have demonstrated that pulpal pain can induce neurogenic inflammatory reactions in gingiva and the expression of pro-inflammatory neuropeptides in gingival crevicular fluid (GCF). Neuropeptides co-ordinate the activity of immuno-effector cells and may influence the secretion of matrix metalloproteinase (MMP)-8, the major tissue-destructive protease in GCF. With this background, we studied whether experimental pulpal pain can trigger changes in GCF MMP-8 levels. The molecular forms of MMP-8 in the GCF of stimulated and non-stimulated teeth were analyzed by Western immunoblot, and MMP-8 levels by quantitative immunofluorometric assay. Painful stimulation of the upper incisor provoked significant elevations in GCF MMP-8 levels of the stimulated tooth. Western immunoblot revealed elevations in both neutrophil- and mesenchymal-type MMP-8 isoforms. At the same time, the GCF MMP-8 levels of the non-stimulated teeth were not changed. Analysis of these data indicated that pulpal pain can induce local elevations in MMP-8 levels in GCF.

On the dynamics of root canal infections-what we understand and what we don't

Infections of the root canal space and their sequelae can be extremely painful and potentially dangerous, yet they do not necessarily have to be. Chronic, asymptomatic inflammatory lesions around the apex of a tooth with a necrotic dental pulp or an insufficient root canal treatment can develop unnoticed by the patient, and remain so for years. The course of disease is modulated by both the virulence of the microbiota established in the root canal space and the capacity of the immune system to curb the infection. To both ends, highly convincing investigations to help us understand when and why the tissues around an endodontically involved tooth become acutely inflamed are missing. We will discuss how recent advances in molecular identification of microorganisms have altered our understanding of root canal infections, and which information is currently missing to link clinical experience with observations from experimental research.

A Prospective Clinical Pilot Study on the Level of Matrix Metalloproteinase-9 in Dental Pulpal Blood as a Marker for the State of Inflammation in the Pulp Tissue

INTRODUCTION

Differentiation between reversible pulpitis (savable pulp) and irreversible inflammation of the pulp tissue (nonsavable pulp) based only on clinical and radiographic diagnoses has proven to be difficult. Pulp exposure allows for the collection of pulpal blood to quantitatively determine the level of inflammation markers or proteolytic enzymes, even with small samples. Pulpitis is associated with the invasion of neutrophil granulocytes and their release of matrix metalloproteinase-9 (MMP-9).

METHODS

Forty-four patients (aged 18-74 years, mean = 35 years), each with 1 tooth with carious pulp exposure presenting with different stages of pulpitis, were included in this prospective, 2-center clinical study; 26 patients presented with irreversible pulpitis (groups 3 and 4), 10 with reversible pulpitis (group 2), and 8 with completely asymptomatic teeth with deep carious lesions (group 1). Six of the 26 patients with teeth diagnosed with irreversible pulpitis had not taken any nonsteroidal anti-inflammatory drugs and were evaluated as a separate group (group 4). Partial pulpotomy and blood sample collection from the pulp chamber were performed. The total levels of MMP-9 and tissue inhibitor of metalloproteinase-1 were assessed by fluorometric and colorimetric enzyme-linked immunosorbent assays, respectively. The Mann-Whitney U test and Spearman rank correlations were used to compare the MMP-9 levels with different stages of pulpal inflammation; significance was set at .05.

RESULTS

The MMP-9 levels in the asymptomatic teeth (group 1) were significantly different from those in the teeth with reversible pulpitis (group 2, P = .006) or irreversible pulpitis (group 4, P < .001). A statistically significant difference was also observed between the MMP-9 levels in group 1 and group 3 (P < .001) in which the patients had taken nonsteroidal anti-inflammatory drugs.

CONCLUSIONS

These findings indicate that the MMP-9 levels in pulpal blood samples could be a useful ancillary diagnostic tool for distinguishing different stages of pulp tissue inflammation.

Inflammatory and immune pathways in the pathogenesis of periodontal disease

The pathogenesis of periodontitis involves a complex immune/inflammatory cascade that is initiated by the bacteria of the oral biofilm that forms naturally on the teeth. The susceptibility to periodontitis appears to be determined by the host response; specifically, the magnitude of the inflammatory response and the differential activation of immune pathways. The purpose of this review was to delineate our current knowledge of the host response in periodontitis. The role of innate immunity, the failure of acute inflammation to resolve (thus becoming chronic), the cytokine pathways that regulate the activation of acquired immunity and the cells and products of the immune system are considered. New information relating to regulation of both inflammation and the immune response will be reviewed in the context of susceptibility to, and perhaps control of, periodontitis.

Role of matrix metalloproteinases in dental caries, pulp and periapical inflammation: An overview

Matrix metalloproteinases (MMPs) are a group of more than 25 secreted and membrane bound enzymes that represent class of enzymes responsible for degradation of pericellular substrates. They have been isolated from dentine, odontoblasts, pulp and periapical tissue. They play an important role in dentine matrix formation, modulating caries progression and secondary dentine formation. Earlier microbial proteolytic enzymes were believed to be responsible for degradation of dentine organic matrix, but lately the accumulated body of evidence suggests that MMPs have an important role in the process. During normal tissue modelling, differentiation during development, in modulating the cell behaviour, maintaining homeostasis and in numerous extracellular pathologic conditions, MMPs tends to be an equally important participant. Odontoblasts secrete some of the essential MMPs for both physiologic and pathologic conditions. MMPs also appear to be a participant in the process of reversible and irreversible pulpitis. Although they tend to have low expression and activity in adult tissues but at the onset of any destructive pathologic process, their production shoots up. They appear to have a significant presence during times of inflammation in the periapical region as well. We take a look at the various factors and evidence pointing towards the role of MMPs in the progression of caries, pulpal and periapical inflammation.

Cytokines induce MMP-3-regulated proliferation of embryonic stem cell-derived odontoblast-like cells

OBJECTIVES

Matrix metalloproteinase (MMP)-3 expression increases after pulpectomy and accelerates angiogenesis in rat dental pulp by an uncharacterised mechanism. Odontoblasts, a major component of dental pulp, could represent a therapeutic target. We investigated whether MMP-3 activity is induced by cytokines and/or is associated with cell proliferation and apoptosis in embryonic stem cell-derived odontoblast-like cells.

MATERIALS AND METHODS

We used reverse transcriptase polymerase chain reaction, western blotting, an MMP-3 activity assay, a BrdU-cell proliferation enzyme-linked immunosorbent assay and DNA fragmentation analysis to evaluate siRNA-mediated downregulation of MMP-3 expression and activity, and any changes in the proliferative and apoptotic responses associated with this reduced expression.

RESULTS

Pro-inflammatory cytokines (interleukin-1β, tumour necrosis factor-α and interferon-γ, at relatively low concentrations) induced MMP-3 mRNA and protein expression, and increased MMP-3 activity and cell proliferation, but not apoptosis. MMP-3 silencing produced a potent and significant suppression of cytokine-induced MMP-3 expression and activity, decreased cell proliferation and increased apoptosis. These effects were rescued by application of exogenous MMP-3.

CONCLUSIONS

Our results suggest that pro-inflammatory cytokines induce MMP-3-regulated cell proliferation and anti-apoptosis effects in odontoblast-like cells derived from embryonic stem cells, in addition to their well-documented destructive role in inflammation.

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.

RETRACTED: Proinflammatory cytokines induce stromelysin-1-mediated cell proliferation in dental pulp fibroblast-like cells

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of a member of the author team as it contains fabricated/falsified data. All of the authors except Nobuaki Ozeki and Taiki Hiyama have agreed to retract the article; N Ozeki left Aichi Gakuin University in March 2018 and does not respond to coauthor inquiries. T Hiyama left Aichi Gakuin University and could not be reached.

Matrix metalloproteinase-3 in odontoblastic cells derived from ips cells: unique proliferation response as odontoblastic cells derived from ES cells

We previously reported that matrix metalloproteinase (MMP)-3 accelerates wound healing following dental pulp injury. In addition, we reported that a proinflammatory cytokine mixture (tumor necrosis factor-α, interleukin (IL)-1β and interferon-γ) induced MMP-3 activity in odontoblast-like cells derived from mouse embryonic stem (ES) cells, suggesting that MMP-3 plays a potential unique physiological role in wound healing and regeneration of dental pulp in odontoblast-like cells. In this study, we tested the hypothesis that upregulation of MMP-3 activity by IL-1β promotes proliferation and apoptosis of purified odontoblast-like cells derived from induced pluripotent stem (iPS) and ES cells. Each odontoblast-like cell was isolated and incubated with different concentrations of IL-1β. MMP-3 mRNA and protein expression were assessed using RT-PCR and western blotting, respectively. MMP-3 activity was measured using immunoprecipitation and a fluorescence substrate. Cell proliferation and apoptosis were determined using ELISA for BrdU and DNA fragmentation, respectively. siRNA was used to reduce MMP-3 transcripts in these cells. Treatment with IL-1β increased MMP-3 mRNA and protein levels, and MMP-3 activity in odontoblast-like cells. Cell proliferation was found to markedly increase with no changes in apoptosis. Endogenous tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 were constitutively expressed during all experiments. The exocytosis inhibitor, Exo1, potently suppressed the appearance of MMP-3 in the conditioned medium. Treatment with siRNA against MMP-3 suppressed an IL-1β-induced increase in MMP-3 expression and activity, and also suppressed cell proliferation, but unexpectedly increased apoptosis in these cells (P<0.05). Exogenous MMP-3 was found to induce cell proliferation in odontoblast-like cells derived from iPS cells and ES cells. This siRNA-mediated increase in apoptosis could be reversed with exogenous MMP-3 stimulation (P<0.05). Taken together, IL-1β induced MMP-3-regulated cell proliferation and suppressed apoptosis in odontoblast-like cells derived from iPS and ES cells.

Tumor necrosis factor-α induces matrix metalloproteinases-3, -10, and -13 in human periodontal ligament cells

BACKGROUND

Various biologic mediators, including matrix metalloproteinases (MMPs), that are implicated in periodontal tissue breakdown can be induced by cytokines. MMPs are known to degrade periodontal ligament attachment, and bone matrix proteins and tissue inhibitors of metalloproteinase (TIMPs) inhibit the activity of MMPs. The aim of this study is to investigate the effect of tumor necrosis factor (TNF)-α on the expression of MMPs in human periodontal ligament (PDL) cells in vitro and establish which MMPs are expressed specifically in response to that stimulus.

METHODS

Cultured PDL cells were stimulated with TNF-α and analyzed with an MMP antibody array. Real-time polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA), and western blot with cell lysate and zymography were used to measure messenger RNA (mRNA) and protein levels of MMP-3, -10, and -13. To examine TNF receptor (TNFR) expression, PDL cells were examined by flow cytometry, and expression of MMP-3, -10, and -13 was observed after blocking the TNFR with an antagonist. Results from real-time PCR, ELISA, and western blot were analyzed by paired t test.

RESULTS

The antibody array showed that the protein most strongly upregulated by TNF-α stimulation was MMP-3, followed by MMP-13 and MMP-10. The TNF-α receptor blocker specifically inhibited expression of MMP-3 and -13. In addition, TNF-α increased levels of MMP mRNAs in MMP-3, -13, and -10 (in decreasing order). However, ELISAs showed that MMP-13 was the most upregulated protein, followed by MMP-10 and MMP-3. Western blotting indicated that TNF-α increased MMP-3 and -13 levels but had no significant effect on the level of MMP-10, and zymography showed that TNF-α increased the activities of all forms of MMP-3 and -13, but MMP-10 was not detected. Flow cytometry demonstrated that the majority of PDL cells expressed TNFR1.

CONCLUSIONS

TNF-α (10 ng/mL) upregulates levels of MMP-3, -10, and -13 in human PDL cells. These results suggest that these proteins play an important role in the inflammation of PDLs.

Temporal expression of metalloproteinase-8 and -13 and their relationships with extracellular matrix metalloproteinase inducer in the development of ligature-induced periodontitis in rats

BACKGROUND AND OBJECTIVE

Matrix metalloproteinases (MMPs) play important roles in extracellular matrix degradation and may be regulated by extracellular matrix metalloproteinase inducer (EMMPRIN). The aim of this study was to investigate the temporal expression and localization of MMP-8 and MMP-13 during the development of ligature-induced periodontitis in rats, and to analyze the correlations of EMMPRIN with MMP-8 and MMP-13 in periodontitis.

MATERIAL AND METHODS

Periodontitis was simulated in rats by ligaturing the cervix of the lower first molars, as described in our previous method. The rats were killed 0, 3, 5, 7, 11, 15 and 21 d after ligation. Micro-computed tomography examinations were performed to detect alveolar bone loss. Semiquantitative western blotting was used to assess the temporal changes in the levels of MMP-8, MMP-13 and EMMPRIN proteins in gingival tissue. Immunohistochemistry was applied to detect the expression and locations of MMP-8 and MMP-13 in gingival tissue and alveolar bone.

RESULTS

Alveolar bone loss showed an exponential increase from days 3 to 11, followed by a slower rate of loss at subsequent study time points. MMP-8 showed a rapid increase of expression from baseline to a peak on day 3, a gradual decrease from days 5 to 7 and then stabilized thereafter. MMP-8 was predominantly located in neutrophil-like cells. Statistically, the expression of MMP-8 was not correlated with the expression of EMMPRIN. The expression of MMP-13 and of EMMRPIN increased from days 3 to 7, and showed a moderate decrease thereafter. The immunoreactivity of MMP-13 was mainly detected in monocytes/macrophages, on the alveolar bone surface, in osteoclasts and in gingival epithelial cells. Statistically, MMP-13 had a strong, positive correlation with EMMPRIN (r = 0.855, p < 0.01).

CONCLUSION

The levels of expression of MMP-8 and MMP-13 are temporally varied at different periods during the development of experimental periodontitis. The level of expression of EMMPRIN is closely associated with the expression of MMP-13, but not with the expression of MMP-8. In addition, MMP-13 might be involved in alveolar bone destruction, as well as in physiological bone remodeling.