MicroRNA-4691-3p inhibits the inflammatory response by targeting STING in human dental pulp cells: A laboratory investigation.

Abstract

AIM:

The regulation of human dental pulp inflammation is not fully understood. This study aims to investigate the effect of miR-4691-3p on the cGAS-STING signalling cascade and its downstream cytokines production in human dental pulp cells (HDPCs).

METHODOLOGY:

Normal dental pulp tissue and pulp tissue with irreversible pulpitis from third molars were collected. HDPCs were isolated from pulp tissue. The expression of STING mRNA and miR-4691-3p was measured by quantitative real-time PCR. Bioinformatic computation via TargetScanHuman 8.0 and a luciferase reporter assay was used to identify the targets of miR-4691-3p. A miR-4691-3p mimic and inhibitor were used to upregulate or downregulate miR-4691-3p expression in HDPCs. HDPCs were transfected with c-di-AMP, c-di-GMP, cGAMP, interferon stimulatory DNA (ISD) and bacterial genomic DNA. Immunoblot was performed to detect the phosphorylation of TBK1, p65 and IRF3. Enzyme-linked immunoassay was performed to detect the cytokines including IFN-β, TNF or IL-6 downstream of cGAS-STING.

RESULTS:

MiR-4691-3p expression was increased in human dental pulp tissue with irreversible pulpitis. Treatment of HDPCs using recombinant human IFN-β, TNF or IL-6 also upregulated miR-4691-3p. The bioinformatic prediction and luciferase reporter assay confirmed that STING was a direct target of miR-4691-3p. The miR-4691-3p mimic suppressed STING expression, the phosphorylation of TBK1, p65 and IRF3, and the IFN-β, TNF or IL-6 production. In contrast, the miR-4691-3p inhibitor enhanced the STING expression, the phosphorylation of TBK1, p65 and IRF3 and the IFN-β, TNF or IL-6 production.

CONCLUSIONS:

MiR-4691-3p negatively regulates the cGAS-STING pathway by directly targeting STING. This provides insight to utilize miRNA-dependent regulatory effect to treat endodontic disease as well as STING-dependent systemic inflammatory disease.

• Authors: Xinxin Tian, Ping Zhang, Fei Liu, Lijie Yang, Kun Fu, Kang Gan, Chao Liu
• Journal: International endodontic journal (Int Endod J) Vol. 56 Issue 11 Pg. 1328-1336 (Nov 2023) ISSN: 1365-2591 [Electronic] England
• PMID: 37403426 (Publication Type: Journal Article)
• Copyright: © 2023 British Endodontic Society. Published by John Wiley & Sons Ltd.