Effects of moxibustion on Treg cells in sarcoma microenvironment

Abstract

Objective: To investigate the therapeutic effect of moxibustion on sarcomas from mesenchymal tissues, which have a low response rate to chemotherapy and radiotherapy.

Methods: S180 sarcoma cell line was inoculated in C57BL/6 mice to form transplanted tumor. Moxibustion therapy was directly applied at the transplanted tumor sites, at a distance of 3.0 cm, 10 min per session, till skin temperature reached 45 °C, once a day, for 14 consecutive days of intervention. After the mice were killed, serum was collected and used to detect concentrations of interleukin-10 (IL-10), transforming growth factor-β1 (TGF-β1), IL-4 and interferon-γ (IFN-γ) by Luminex liquid suspension chip. The numbers of Treg⁺ T cells and CD4⁺CD25⁺Forkhead Box P3 (Foxp3)⁺ T cells were detected by flow cytometry. Fluorescence in situ hybridization was used to analyze the changes of CD4, CD8, Foxp3 and TGF-β1 in the tumor microenvironment (TME).

Results: Weight of S180 transplanted tumor in the control group was (2.03 ± 0.54) g, and that in the moxibustion group was (1.27 ± 0.29) g, which was statistically different (P = 0.023). The mean value of Foxp3⁺ T cells in the normal group was 2.01%, which increased to 3.63% after the formation of transplanted tumor, and decreased to 1.48% after moxibustion treatment. The moxibustion group also had reduced numbers of CD4⁺CD25⁺Foxp3⁺ T cells in the spleen of mice with transplanted tumor. The concentrations of IL-10, TGF-β1 and IL-4 decreased in the serum of mice with transplanted tumor, while the concentration of IFN-γ increased. Moxibustion was associated with downregulation in expression of Foxp3, IL-10 and TGF-β1 genes in the transplanted tumor, and increases in the gene expression of CD4⁺ T cells and CD8⁺ T cells in the TME.

Conclusion: Moxibustion may have therapeutic effects on sarcomas by reducing the number of Treg cells in the blood and controlling the infiltration of Treg cells in the TME.

Keywords: Moxibustion; Sarcoma; Treg cells; Tumor microenvironment.