The role of IL‐6 on apical periodontitis: a systematic review

Abstract

The aim of this review was to examine current knowledge of the role of interleukin-6 (IL-6) in apical periodontitis (AP) pathogenesis as an inflammatory or pro-inflammatory cytokine. It also looked at whether IL-6 could serve as a measure for differential diagnosis or as a biomarker that can further predict the progression of bone resorption. A systematic review relating to AP and IL-6 was made via PubMed, BIOSIS, Cochrane, EMBASE and Web of Science databases using keywords and controlled vocabulary. Two independent reviewers first screened titles and abstracts and then the full texts. The reference lists of the identified publications were examined for additional titles. Eighteen papers were studied in total. In vitro studies (n = 6) revealed that IL-6 is present in AP, and its levels are proportional to the size of the periapical lesions. Neutrophils and macrophages resident in these lesions can produce IL-6 in vitro after a bacterial stimulus. Animal studies (n = 5) showed that IL-6 is present in AP and that osteoblasts can produce IL-6 in vivo. On the other hand, two studies using IL-6 knockout mice revealed larger periapical lesions when compared with control groups, demonstrating IL-6's role as an anti-inflammatory cytokine. In human studies (n = 7), IL-6 was identified in AP, and its levels were higher in symptomatic, epithelialized and large lesions than in asymptomatic and small lesions. These data lead to the conclusion that IL-6 may play a pro-inflammatory role, increasing its levels and reabsorbing bone in the presence of infections. When IL-6 is not present, other cytokines such as IL-1 and TNF-α induce bone resorption. Further studies about the relationship between AP development and the cytokine network must be performed to establish the exact role of each cytokine in the inflammatory process.

The effect of dental bleaching on pulpal tissue response in a diabetic animal model: a study of immunoregulatory cytokines

“…One cytokine can act on several target cells, and many cytokines can interact on only one target cell, showing synergistic or antagonistic affects depending on the microenvironment (Azuma et al . ).…”

Concentration‐dependent effect of bleaching agents on the immunolabelling of interleukin‐6, interleukin‐17 and CD5‐positive cells in the dental pulp

“…Interleukin (IL)-6 was observed soon after tooth bleaching in human dental pulp cells (Soares et al 2015), but this has not been investigated over time. This interleukin can promote the attraction of neutrophils and increase vascular permeability in the pulp chamber (Elsalhy et al 2013, Xiong et al 2015, consequently generating increased oedema (Elsalhy et al 2013), which contributes to inflammation of the pulp tissue (Azuma et al 2015).…”

Immunoinflammatory response and bioactive potential of GuttaFlow bioseal and MTA Fillapex in the rat subcutaneous tissue

“…A biocompatible material may allow the release of mediators by host cells which promote the regression of the inflammatory reaction 4,18,[20][21][22] and stimulate the tissue repair 5,22 . Among the cytokines and growth factors, the interleukin-6 (IL-6) has a participation in the initiation and maintenance of the inflammatory reaction 4,5,[23][24][25] . Other chemokine involved in the inflammatory reaction is the vascular endothelial growth factor (VEGF), an angiogenic factor that increases the vascular permeability 26 favouring the recruitment of inflammatory cells in the beginning of the inflammatory reaction 27 , and plays an essential role in the tissue remodelling 28 and wound healing 27 .…”