Clinical endodontic procedures modulate periapical cytokine and chemokine gene expressions

Objectives To identify the gene expression of the cytokines IL-9, TNF-α, IL-1, INF-γ, IL-17A, and IL-10 and the chemokines CCL-2/MCP-1 and CCR-6 in the periapical fluid of human root canal infections. Materials and methods Twenty samples were collected immediately and 7 days after the cleaning and shaping procedures (after reducing the intracanal microbial load) in an attempt to characterize the expression of these genes. The endogenous expression levels of cytokines and chemokines were analyzed by real-time polymerase chain reaction. The Shapiro-Wilk and the Wilcoxon tests analyzed data. Results Significantly higher levels of the IL-9, INF-γ, TNF-α, IL-1, and IL-10 markers on day 7 were observed compared with day 0 ( p < 0.05). However, IL-17A and the chemokines CCL-2/MCP-1 and CCR-6 did not show a significant difference in mRNA expression when comparing both timepoints ( p > 0.05). Conclusions The clinical variation of the periapical immune status after endodontic therapy suggests that the cytokine and chemokine-mediated pro-inflammatory response appears to be modulated in an IL-10/IL-9-dependent manner. Clinical relevance Few studies have investigated the role of Th9 cells in periapical lesions. IL-9 presents exciting plasticity, performing immunosuppressive actions, and it is also capable of changing their phenotype in the presence of IL-17. Hence, it is relevant to investigate its role in the context of the known mediators involved the periapical immune process.