Clinical endodontic procedures modulate periapical cytokine and chemokine gene expressions

Zoledronic Acid Modulates Cytokine Expression and Mitigates Bone Loss during the Development of Induced Apical Periodontitis in a Mice Model

INTRODUCTION

Bisphosphonates are antiresorptive drugs used worldwide to treat systemic bone pathologies. This study aimed to assess the impact of zoledronic acid on the progression of induced apical periodontitis and the expression of cytokines interleukin (IL)-1β, IL-10, IL-6, and tumor necrosis factor alpha (TNF-α) in a mouse model.

METHODS

Sixteen female isogenic BALB/c mice 6 weeks of age were distributed into 2 groups: mice with induced apical periodontitis (the AP group, n = 8) and mice with induced apical periodontitis treated with zoledronic acid (the AP-ZA group, n = 8). The AP-ZA group received a dose of 125 μg/kg zoledronic acid diluted in sterile saline solution administered intraperitoneally once a week for 4 weeks before pulp exposure, whereas the AP group received only saline solution. Pulp exposures were performed on the maxillary first molars for the induction of apical periodontitis, and mice were euthanized after 7 and 21 days. The jaws were collected; scanned using micro-computed tomographic imaging; and processed for polymerase chain reaction analysis of IL-1β, IL-10, IL-6, and TNF-α. The Student t test was performed for parametric data, and Mann-Whitney U tests were used for nonparametric data. The level of significance was set at 5%.

RESULTS

Micro-computed tomographic imaging revealed higher bone resorption in the AP group compared with the AP-ZA group at both time points (P < .05). Real-time polymerase chain reaction demonstrated higher TNF-α expression in the AP group at both time points and higher IL-6 and IL-1β expression in the AP group at the 7- and 21-day time points, respectively, compared with the AP-ZA group (P < .05). No differences were observed regarding IL-10 expression between the groups.

CONCLUSIONS

Zoledronic acid had significant anti-inflammatory and antiresorptive effects on apical periodontitis in mice.

Revisiting the role of IL-1 signaling in the development of apical periodontitis

Apical periodontitis (AP) develops as a result of an immune response to pulpal bacterial infection, and various cytokines are involved in the pathogenesis of AP, with Interleukin (IL)-1 being considered a key cytokine. The role of IL-1 in the pathogenesis of AP has been well studied. It is known that IL-1 expression in periapical lesions correlates closely with the development of AP. IL-1 is a potent bone-resorptive cytokine that induces osteoclast formation and activation. Hence, inhibiting its signaling with IL-1 receptor antagonist (IL-1RA) results in a reduction in periapical lesion size. On the other hand, IL-1 is also a central cytokine that combats bacterial infection by activating innate immune responses. Therefore, a complete loss of IL-1 signaling leads to a failure to limit bacterial dissemination and consequently exacerbates AP. In vivo, IL-1 expression is tightly regulated and its signaling is modulated to optimize the immune response. Obesity causes systemic low-grade chronic inflammation and increases the risk of cardiovascular, renal, and other disorders. In experimentally induced AP, obesity significantly increases periapical bone loss, albeit the underlying mechanism remains unclear. Recent technological innovations have enabled more comprehensive and detailed analyses than previously, leading to new insights into the role of IL-1RA in regulating IL-1 signaling, and modulating apical lesion progression in obesity. In this review, we provide a brief overview of the function of IL-1 in AP development, with special emphasis on the latest findings in normal weight and obese states.

Electrospun Nanofiber Films Suppress Inflammation In Vitro and Eradicate Endodontic Bacterial Infection in an E. faecalis-Infected Ex Vivo Human Tooth Culture Model

Treatment failure of endodontic infections and their concurrent inflammations is commonly associated with microbial persistence and reinfection, also stemming from the anatomical restrictions of the root canal system. Aiming to address the shortcomings of current treatment options, a fast-disintegrating nanofibrous film was developed for the intracanal coadministration of an antimicrobial (ZnO nanoparticles) and an anti-inflammatory (ketoprofen) agent. The electrospun films were fabricated based on polymers that dissolve rapidly to constitute the actives readily available at the site of action, aiming to eliminate both microbial infection and inflammation. The anti-inflammatory potency of the nanofiber films was assessed in an in vitro model of lipopolysaccharide (LPS)-stimulated RAW 264.7 cells after confirming their biocompatibility in the same cell line. The nanofiber films were found effective against Enterococcus faecalis, one of the most prominent pathogens inside the root canal space, both in vitro and ex vivo using a human tooth model experimentally infected with E. faecalis. The physical properties and antibacterial and anti-inflammatory potency of the proposed electrospun nanofiber films constitute a promising therapeutic module in the endodontic therapy of nonvital infected teeth. All manuscripts must be accompanied by an abstract. The abstract should briefly state the problem or purpose of the research, indicate the theoretical or experimental plan used, summarize the principal findings, and point out major conclusions.

Present status and future directions - microbiology of endodontic infections

Apical periodontitis has a microbial aetiology and is one of the most common inflammatory diseases that affect humans. Fungi, archaea and viruses have been found in association with apical periodontitis, but bacteria are by far the most prevalent and dominant microorganisms in endodontic infections. Bacterial infection of the root canal system only occurs when the pulp is necrotic or was removed for previous treatment. In some specific cases, including acute and chronic abscesses, the bacterial infection may reach the periradicular tissues. Intracanal bacteria are usually observed as sessile multispecies communities (biofilms) attached to the dentinal root canal walls. Infection in the main root canal lumen can spread to other areas of the root canal system. Although more than 500 bacterial species have been detected in endodontic infections, a selected group of 20 to 30 species are most frequently detected and may be considered as the core microbiome. There is a high interindividual variability in the endodontic microbiome in terms of species composition and relative abundance. Obligate anaerobic species are more abundant in the intraradicular bacterial communities of teeth with primary apical periodontitis, while both anaerobes and facultatives dominate the communities in post-treatment apical periodontitis. Bacterial interactions play an essential role in determining the overall virulence of the community, which has been regarded as the unit of pathogenicity of apical periodontitis. This article reviews the microbiologic aspects of endodontic infections and provides perspectives for future research and directions in the field.

Influence of Bacterial Profiles in Cytokine and Clinical Features of Endodontic Disease

INTRODUCTION

We verified the association between selected bacterial profiles and levels of cytokines, chemokines, and the expression of signs and symptoms of primary endodontic infection with apical periodontitis.

METHODS

Samples were collected from 21 root canals, and macrophages were stimulated for 24 hours. Tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, IL-10, IL-12p70, interferon gamma, and chemokine (C-C motif) ligand 2 (CCL2) were measured using cytometric bead array. We investigated the overlapping networks between cytokines and chemokines with regression analysis. Checkerboard DNA-DNA hybridization was used to assess 40 target bacteria species. Using factor analysis, bacterial species aggregated in 2 factors. The association of bacteria species-based factors on cytokine and chemokine levels and clinical features was estimated with regression analysis.

RESULTS

A negative relationship between IL-10 (anti-inflammatory cytokine) and CCL2, TNF-α, and IFN-γ (proinflammatory cytokines) (all P < .05) was observed. CCL2 was positively correlated with TNF-α (P < .01). Thirty-eight bacteria species were detected in primary endodontic infection with apical periodontitis. The first bacteria species-based factor was associated with the size of the radiolucent area (coefficient = 15.42) and tenderness to percussion/pain on palpation (coefficient = 20.79). The second factor was associated with CCL2 levels (coefficient = 1.28).

CONCLUSIONS

Different bacterial profiles can be differentially related to the expression of inflammatory proteins and the experience of clinical features.

Outcome measures to assess the effectiveness of endodontic treatment for pulpitis and apical periodontitis for use in the development of European Society of Endodontology (ESE) S3 level clinical practice guidelines: a protocol

The European Society of Endodontology (ESE) is in the process of developing S3Level Clinical Practice Guidelines for the treatment of pulpal and apical disease for the benefit of clinicians and patients. In order to ensure a homogenous review process in the development of the clinical practice guidelines, it is essential that the core outcomes for all endodontic treatments are standardized and recommendations are made regarding minimum follow-up time specific to each outcome measure. In the absence of a recognized core outcome set in Endodontics, the current project aimed to follow an established consensus process to define the most appropriate clinician and patient-reported outcomes. As part of the project, recommendations will also be agreed regarding an acceptable minimum follow-up period for studies by literature review and group discussion. The selected outcome measures and follow-up periods will be used in subsequent systematic analyses of the literature to investigate the effectiveness of endodontic treatment to alleviate pulpitis and apical periodontitis. In this paper, previous reviews, ESE Guidelines and Position Statements were searched in order to compile a list of potentially important outcome measures for the treatment of pulpitis (working group 1), the nonsurgical treatment of apical periodontitis (working group 2), the surgical treatment of apical periodontitis (working group 3) and the regenerative treatment of apical periodontitis (working group 4). Initially, the two S3 guideline leads selected two independent senior clinical academics with experience of evidence-based dentistry to lead each of the four working groups forming a 10-member steering group. The working group leads in turn selected 32 academics with experience of evidence-based dentistry to lead the individual systematic reviews contained within the respective working groups. These 42 individuals make up the Guideline Development Group (GDG). Prior to the selected systematic reviewers commencing writing and submitting the review protocol, the complete list of outcome variables identified in this document will be ranked by the 42 members of the GDG in their importance to the individual patient using a 9-point Likert scale. A summary of the survey scores will thereafter be shared with the members of the group and the final list of clinician and patient-reported outcome measures rated as critical for decision making (7-9 on Likert scale by majority of survey participants) to guide systematic reviews will be consented and confirmed during an online meeting of the steering group. In this online meeting, another aspect with regard to meaningfulness of clinical trial results to be addressed in systematic reviews will be consented: length of follow-up. In order to develop high quality guidelines, it is suggested that the follow-up period after treatment should be related to the specific outcome measure being addressed; however, a minimum of one year for assessing the effectiveness of treatments for pulpitis and apical periodontitis should be considered. It is accepted, that selected research questions that focus on pain, swelling, medication taken or investigating diagnostic accuracy are likely to have shorter follow-up periods. As a result of the GDG consensus process, the outcome measures and length of follow-up will, alongside the use of standard instruments to assess the methodological quality of clinical trials and other comparative studies, be applied to all the commissioned systematic reviews that will inform the subsequent process when developing the ESE S3 Level Clinical Practice Guidelines.

Immunological profile of periapical endodontic infection in patients undergoing haematopoietic transplantation

OBJECTIVES

To evaluate the mRNA expression levels of cytokines interferon-γ, tumour necrosis factor-α, interleukin IL-1β, IL-10, and the chemokine CCL2/MCP-1, CCL4, and CXCR4 in the periapical interstitial fluid from root canal infections before and after bacterial load reduction in patients undergoing haematopoietic stem cell transplantation (HSCT).

MATERIALS AND METHODS

The case group was composed of 10 patients undergoing HSCT, and our control group included 10 healthy patients. Clinical samples were taken from teeth with pulp necrosis. Three paper points were placed in the RCS and maintained for 2 min for microbial evaluation before cleaning and shaping procedures. After cleaning and drying the canal, three paper points were introduced into the root canal, passing passively through the root apex (2 mm) into the periapical tissues for 1 min. Samples were collected immediately after root canal cleaning and 7 days later (restrained root canal bacterial load) to characterize gene expression using real-time PCR.

RESULTS

The results showed significantly reduction in the microbial load on day 7. An increased expression level of TNF-α and IFN-γ on day 7 in control and case groups was observed (p < 0.05). The mRNA levels of IL-1β and IL-10 in the pre-HSCT group increased in the samples from day 7 (p < 0.05). The chemokine CCL-2/MCP-1 was not detected in pre-HSCT group. Chemokine receptor CXCR4 levels increased in samples obtained from the day 7 in the control group (p < 0.05).

CONCLUSIONS

Individuals undergoing HSTC presented similar cytokine and chemokine mRNA expression compared with healthy individuals. However, it was observed the total absence of mRNA MCP-1/CCL2 expression in those individuals undergoing HSCT.

CLINICAL RELEVANCE

Patients undergoing HSCT are at higher risk of infection. No study has analysed the periapical immune responses to root canal infections in HSCT individuals.