IL-6/STAT3-Mediated miR-181a-5p in Bone Marrow-Derived Mesenchymal Stem Cells Regulates Th17/Treg Balance in Experimental Periodontitis.

OBJECTIVE

Periodontitis adversely affects oral and overall health. Bone marrow-derived mesenchymal stem cells (BMMSCs) play regulatory roles in the immune system, and the exploration of therapeutic strategies involving BMMSCs has garnered significant attention in the context of inflammatory pathological processes. Interleukin-6 can regulate microRNA expression by activating the signal transducer and activator of transcription 3 (STAT3) and functions in some systemic diseases. Notably, the regulatory mechanisms between IL-6 and miR-181a-5p in BMMSCs underlying periodontitis are still unknown. This study aims to uncover the regulatory mechanisms between IL-6 and miR-181a-5p and create a new treatment strategy for periodontal tissue regeneration.

METHODS

In this study, Western blot was used to assess IL-6 and STAT3 levels. Quantitative real-time polymerase chain reaction assessed the expression of miR-181a-5p and the relative genes. Enzyme-linked immunosorbent assay detected the content of IL-6. The Cell Counting Kit-8 was used to evaluate cell viability. Alkaline phosphatase staining was used to analyse the osteogenesis of cells. Chromatin immunoprecipitation and dual luciferase activity assays were used to verify the binding relationship between miR-181a-5p, STAT3, and IL-6. Flow cytometry was used for identifying cell types. Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology analysed potential signal pathways of genes targeted by miR-181a-5p. In addition, the present research was further investigated using a ligature-induced periodontitis model in mice. The micro-computed tomography, haematoxylin and eosin, and tartrate-resistant acid phosphatase (TRAP) assays were used for histologic analysis of the degree of inflammation and bone recovery in the experimental periodontitis and treatment group.

RESULTS

IL-6 and miR-181a-5p were upregulated in experimental periodontitis in mice. The IL-6 recombinant protein promoted mBMMSC proliferation and upregulated miR-181a-5p levels via STAT3. Functional inhibition of miR-181a-5p alleviated the T helper 17 (Th17) cell/regulatory T cell (Treg) immune imbalance triggered by IL-6 stimulation. Injection of miR-181a-5p inhibitor preconditioned mBMMSCs significantly promoted periodontal tissue regeneration, and osteoclasts and bone resorption were reduced significantly.

CONCLUSION

IL-6 may contribute to the progression of experimental periodontitis in mice via modulating STAT3‑mediated miR‑181a‑5p expression in mBMMSCs and may potentially influence periodontal tissue regeneration through regulating the Th17/Treg balance.