Mechanism of Panax Notoginseng Saponins Regulates HIF-1α/PDHK1 Pathway-mediated Aerobic Oxidation of CD4⁺ T Cells to Promote Treg Differentiation

OBJECTIVE  To observe the regulation of aerobic oxidation mediated by HIF-1α/PDHK1 pathway by PNS, and to explore its mechanism of promoting the differentiation of Naive CD4⁺T cells into Treg cells.

METHODS  Naive CD4⁺T cells were isolated from the spleen of C57BL/6 mice by magnetic beads and induced to differentiate into Treg cells for in vitro culture. Naive CD4⁺T cells were divided into PNS treatment group(5, 10, 20 μg·mL⁻¹), PNS combined with HIF-1α inhibitor(PX-478) group, and the control group was set up. The proportion of Treg cells differentiation was detected by flow cytometry. The expression of HIF-1α and PDHK1 protein was detected by Western blotting. The expression of HIF-1α, PDHK1 and FOXP3 mRNA was detected by real-time fluorescence quantitative PCR. The level of IL-10 in cell culture supernatant was detected by enzyme-linked immunosorbent assay.

RESULTS  PNS could significantly increase the proportion of Treg cells and the secretion level of IL-10, and increase the expression of FOXP3 mRNA in cells. At the same time, the expression of HIF-1α and PDHK1 protein and mRNA was inhibited. When the cells were treated with 10 μmol·L⁻¹ PX-478 and then treated with 10 μg·mL⁻¹ PNS, the expression of PDHK1 and FOXP3 and the differentiation ratio of Treg cells were not significantly different from those treated with 10 μmol·L⁻¹ PX-478 alone.

CONCLUSION  PNS can reduce the expression level of PDHK1 by HIF-1α to enhance the aerobic oxidation of Naive CD4⁺T cells and promote their differentiation into Treg cells.